Friction agitation joining method, method for manufacturing joined butted members and friction agitation joining apparatus

In a friction agitation joining method, two plate-shaped joining members different in thickness, or first and second joining members, are abutted against each other with a level difference formed at upper surface sides thereof. A rotating probe of a joining tool is inserted into the butted portion of the first and second joining members from upper surface sides thereof. Joining-direction front sides of the first and second joining members with respect to the probe inserted position are pressed by first and second front pressing rollers, respectively, from the upper surface sides thereof. Furthermore, joining-direction lower sides of the first and the second joining members with respect to a probe inserted position from the upper surface sides are pressed by first and second lower pressing rollers, respectively, from the upper surface sides thereof. In this state, the butted portion is joined by the friction agitation joining method.

TECHNICAL FIELD

The present invention relates to a friction agitation joining method, a method for manufacturing joined butted members and a friction agitation joining apparatus preferably used for manufacturing metal plate-shaped members used as, for example, flooring materials, wall materials and ceiling materials for transporting device such as automobiles, aircrafts and railroad vehicles.

BACKGROUND ART

A friction agitation joining method belongs to a category of a solid state welding method. The friction agitation joining method has such advantages that it can be applied to various metal joining members regardless of the materials and that joining members are hardly deformed by thermal strains at the time of joining. Thus, in recent years, the method has been used for joining various structural members.

This friction agitation joining method will be explained with reference toFIGS. 29 to 31. In these figures, the reference numeral101denotes a long and thin plate-shaped metal first joining member, and102denotes a long and thick plate-shaped metal second joining member. These joining members101and102are butted against each other at the widthwise sides thereof with the lower surfaces being flush with each other (the reference numeral103denotes the butted portion). Thus, the level difference corresponding to the thickness difference is formed at the surface side thereof. In this butted state, these joining members101and102are supported from the lower surface sides thereof by the forward and backward supporting rollers131and132. The reference numeral104denotes a stepped portion formed at the surface side of the joining members101and102.

The reference numeral140denotes a joining tool for performing a friction agitation joining method. This joining tool140is equipped with a columnar rotor141having a larger diameter and a pin-shaped probe142having a smaller diameter integrally protruded from the rotational center of the end surface of the rotor141and extending along the rotation axis Q′.

The reference numeral133denotes a backing roller. This backing roller133is disposed at the lower surface side of the joining members101and102opposite to the probe142of the joining tool140.

When joining the butted portion103of the joining members101and102using the friction agitation joining tool140, first, the rotating probe142of the joining tool140is inserted into the butted portion103of the joining members101and102from the upper side thereof. Then, in this inserted state, both the joining members101and102are moved in a longitudinal direction thereof with the probe inserted in the butted portion103so that the probe142advances along the butted portion103. “MD′” denotes the moving direction of both the joining members101and102. In accordance with the movement of both the joining members101and102, the butted portion103of both the joining members101and102is joined by the probe142at the probe inserted position. The reference numeral103′ denotes a joined (i.e., welded) butted portion of the joining members101and102. “W′” denotes a joined portion formed at the butted portion103′. Furthermore, “WD′” shows the joining direction in this friction agitation joining method.

In cases where the joining members101and102are twisted or curved in the thickness direction, i.e., not formed into a flat shape, joining of such joining members101and102causes a defect of shape. As a result, high quality joined butted members cannot be obtained. Furthermore, if these joining members101and102are butted against each other in the state that they have torsion, clearance (not shown) resulting from the torsion of the joining members101and102will be generated at the butted portion103. Accordingly, if the butted portion103is joined in this state, a joining defect such as a non-joined portion will occur in the joined portion103′ by the clearance. Furthermore, in cases where the joining members are long or thin members, even if these members are joined by friction agitation joining, thermal distortion due to the joining tends to be produced.

In order to solve this problem, Japanese Unexamined Laid-open Patent Publication No. H10-296462 proposes the following method. In this method, a butted portion will be joined/welded while pressing the joining-direction forward side of both the joining members101and102with respect to a probe inserted position from the upper surface side thereof by a cylindrical forward pressing roller110having a certain length and bridging over both the joining members101and102, and also pressing the joining-direction backward side of both the joining members101and102with respect to a probe inserted position from the upper surface side thereof by a cylindrical backward pressing roller110having a certain length and bridging over both the joining members101and102.

However, since the stepped portion104is formed on the surface of the butted portion103of the joining members101and102, according to the aforementioned proposed method, even if the forward and backward pressing rollers110and120are intended to press both the joining members101and102, it was able to press down the thicker joining member102with the forward and backward pressing rollers110and120, but was not able to press down the thinner joining member101. As a result, neither torsion nor curvature could be corrected. Therefore, the joining members101and102are joined in a state that they have torsion or curvature, and therefore configuration defects, joining defects such as a non-joined state and thermal distortion occur. Accordingly, high quality joined butted members cannot be obtained.

Now, generally, in a friction agitation joining method, it is desirable to execute the joining method in a state in which the probe142of the joining tool140is deeply inserted into the butted portion103so as to join the butted portion103in the entire thickness direction thereof.

However, if the friction agitation joining is performed in a state in which the probe142is inserted as mentioned above, the tip of the probe142may project from the lower surface of the butted portion103of the joining members101and102during the joining process, which in turn may cause a damage to the backing member such as a backing roller133. In order to prevent such a fault, as shown inFIG. 30, generally the probe142is inserted so as to keep the distance between the tip of the probe142and the lower surface of the butted portion103. However, this insufficient insertion of the probe142causes insufficient joining of the butted portion103with respect to the thickness direction. As a result, as shown inFIG. 31, the root remaining portion R tends to remain in the lower surface of the joined butted portion103′ where both the joining members101and102are joined. This root remaining portion R causes reduced bonding strength of the butted joining members.

As shown inFIGS. 30 and 31, especially in cases where both the joining members101and102are butted against each other with a level difference formed on the surface side in the thickness direction, the root remaining portion R tends to remain. That is, in cases where both the joining members101and102are butted against each other as mentioned above, it is difficult to stably dispose the end surface141aof the rotor141of the joining tool140on both the joining members101and102, and therefore as shown inFIG. 30, the rotor141tends to incline to the first joining member side101or the second joining member side102unexpectedly. Thus, at the time of inclination of the rotor141, since the insertion depth of the probe142in the butted portion103changes, it is necessary to reduce the insertion depth of the probe142for safety, which in turn tends to generate the root remaining portion R.

Furthermore, as shown inFIG. 30, in this case, since the rotor141of the joining tool140is usually disposed in a inclined state toward the first joining member side101, it is difficult to strictly set the insertion depth of the probe142into the butted portion103. Furthermore, since the insertion depth of the probe142increases because the shoulder portion102aof the second joining member102deforms plastically during the joining, it is necessary to decrease the insertion depth of the probe142. For this reason, the root remaining portion R tends to remain.

Furthermore, since the thickness of manufactured joining member101and102is uneven, it is difficult to keep the constant insertion depth of the probe142. From this point too, the root remaining portion R tends to remain.

The present invention was made in view of the aforementioned technical background.

It is a first object of the present invention to provide a friction agitation joining method, a method for manufacturing joined butted members and a friction agitation joining apparatus capable of preventing a generation of configuration defects such as twist or curvature and a generation of poor junction such as joint defect or thermal distortion, to thereby provide high quality joined butted members.

It is a second object of the present invention to provide a friction agitation joining method, a method for manufacturing joined butted members and a friction agitation joining apparatus capable of preventing a generation of a root remaining portion to thereby provide high quality joined butted members.

Other objects and advantages of the present invention will be apparent from the following preferred embodiments.

DISCLOSURE OF INVENTION

In order to attain the aforementioned first object of the present invention, according to the first aspect of the present invention, in a friction agitation joining method for joining a first joining member and a second joining member butted against each other with a level difference formed at upper surface sides thereof by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from the upper surface sides so that the probe advances along the butted portion, joining of the butted portion is performed while pressing joining-direction forward sides of the first joining member and the second joining member with respect to a probe inserted position from the upper surface sides by a first forward pressing roller and a second forward pressing roller, respectively.

According to the first aspect of the present invention, by pressing joining-direction forward sides of the first joining member and the second joining member with respect to a probe inserted position from the upper surface sides by a first forward pressing roller and a second forward pressing roller, respectively, it is possible to prevent a fault such as an unexpected movement of each joining member during the joining and also to correct the configuration defect of each joining member such as torsion or curvature. Furthermore, performing the joining process in this state can prevent the generation of poor junction such as joint defect or thermal distortion, resulting in high quality butted joining members.

In order to attain the aforementioned first object of the present invention, according to the second aspect of the present invention, in a friction agitation joining method for joining a first joining member and a second joining member butted against each other with a level difference formed at upper surface sides thereof by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from the upper surface sides so that the probe advances along the butted portion, joining of the butted portion is performed while pressing joining-direction backward sides of the first joining member and the second joining member with respect to a probe inserted position from the upper surface sides by a first backward pressing roller and a second backward pressing roller, respectively.

According to the second aspect of the present invention, by pressing joining-direction backward sides of the first joining member and the second joining member with respect to a probe inserted position from the upper surface sides by a first backward pressing roller and a second backward pressing roller, respectively, it is possible to prevent a fault such as an unexpected movement of each joining member during the joining and also to correct the configuration defect of each joining member such as torsion or curvature. Furthermore, performing the joining process in this state can prevent the generation of poor junction such as joint defect or thermal distortion, resulting in high quality joined butted members.

In order to attain the aforementioned first object of the present invention, according to the third aspect of the present invention, in friction agitation joining method for joining a first joining member and a second joining member butted against each other with a level difference formed at upper surface sides thereof by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from the upper surface sides so that the probe advances along the butted portion, joining of the butted portion is performed while pressing joining-direction forward sides of the first joining member and the second joining member with respect to a probe inserted position from the upper surface sides by a first forward pressing roller and a second forward pressing roller, respectively, and pressing joining-direction backward sides of the first joining member and the second joining member with respect to a probe inserted position from the upper surface sides by a first backward pressing roller and a second backward pressing roller, respectively.

According to the third aspect of the present invention, joining-direction forward sides of the first joining member and the second joining member with respect to a probe inserted position is pressed from the upper surface sides by a first forward pressing roller and a second forward pressing roller, respectively. Furthermore, joining-direction backward sides of the first joining member and the second joining member with respect to a probe inserted position is pressed from the upper surface sides by a first backward pressing roller and a second backward pressing roller, respectively. Accordingly, it is possible to prevent a fault such as an unexpected movement of each joining member during the joining and also to correct the configuration defect of each joining member such as torsion or curvature. Furthermore, performing the joining process in this state can prevent the generation of poor junction such as joint defect or thermal distortion, resulting in high quality joined butted members.

In the first or third aspect of the present invention, a metal member, for example, may be used as a joining member. Furthermore, at the time of joining operation, both the joining members are usually supported by the support member from the lower surface side thereof. As this support member (means), various means including the support roller which will be mentioned later can be used.

In the aforementioned first or third aspect of the present invention, it is preferable that the joining of the butted portion is performed while pressing at least a portion near the butted portion at the joining-direction forward side of the first joining member with respect to a probe inserted position and at least a portion near the butted portion at the joining-direction forward side of the second joining member with respect to a probe inserted position from the upper surface sides by the first forward pressing roller and the second forward pressing roller, respectively.

In this case, each joining member can be pressed assuredly. As a result, the generation of poor junction such as joint defect or thermal distortion can be prevented more assuredly, resulting in high quality joined butted members.

In any one of the first to third aspects of the present invention, it is preferable that the joining of the butted portion is performed while pressing a joined butted portion of the first and second joining members from the upper surface sides by a third backward pressing roller with a tapered periphery.

In this case, by pressing the joined butted portion by the third backward pressing roller, the joined butted portion is pressed by the pressing force from the third backward pressing roller and thereby plastically deformed, so that the surface becomes into an inclined surface. Furthermore, due to this plastic deformation, the materials of the shoulder portion of the joining members will be filled in the corner of the stepped portion. Furthermore, minute unevenness, such as a burr which may sometimes be generated on the surface of the joined butted portion, is pressed and removed by receiving the press force from the third backward pressing roller. Accordingly, the surface of the joined butted portion is formed into an inclined surface and smoothed with the inclined state. When the surface of the joined butted portion is formed into such an inclined surface, the stress concentration produced in the stepped portion of the obtained butted joining members is relieved. Furthermore, when the joined butted portion is pressed as mentioned above, the tension residual stress produced on the surface of the joined butted portion is converted into a compression residual stress, which enhances the durability of the butted joining members. Furthermore, since the surface of the joined butted portion is smoothed, the generating of the film defects due to the aforementioned minute unevenness which may sometimes be generated at the time of painting can be prevented. As a result, it becomes possible to form a film on the surface of the joined butted portion appropriately.

It is preferable that the periphery of the third backward pressing roller is cooled. In this case, the upper surface of the joined butted portion of the joining members is forcibly cooled by being contacted by the cooled periphery of the roller. Thereby, the joined butted portion is quenched. Accordingly, the joining strength improves. Furthermore, the superfluous heat produced in the joined butted portion is removed, resulting in, a good joining state.

In any one of the aforementioned first to third aspects of the present invention, it is preferable that the joining of the butted portion is performed while cooling a lower surface of a joined butted portion of the first and second joining members by keeping a cooled periphery of a cooling roller in contact with the lower surface.

In this case, the lower surface of the joined butted portion of the joining members is forcibly cooled by being contacted by the cooled periphery of the roller. Thereby, the joined butted portion is quenched. Accordingly, the joining strength improves. Furthermore, the superfluous heat produced in the joined butted portion is removed, resulting in a good joining state.

In the first or third aspect of the present invention, it is preferable that the first forward pressing roller and the second forward pressing roller are separate members, and that the joining of the butted portion is performed in a state in which an axis of at least one of rollers including the first forward pressing roller and the second forward pressing roller is inclined with respect to a butting direction of the joining members within a plane perpendicular to a joining direction.

In this case, since the first forward pressing roller and the second forward pressing roller are separate members, even if the thick dimension of at least one of the joining members fluctuates in a direction parallel to the joining direction, the joining members can be pressed firmly. Furthermore, by inclining an axis of at least one of rollers including the first forward pressing roller and the second forward pressing roller with respect to the butting direction of the joining members within a plane perpendicular to the joining direction, the pressing force from the roller received by the joining member can be changed in the butting direction. Then, by joining the butted portion in this state, the generation of poor junction such as joint defect or thermal distortion can be prevented more assuredly.

In the first or third aspect of the present invention, it is preferable that the first forward pressing roller and the second forward pressing roller are separate members, and that the joining of the butted portion is performed while changing at least one of an inclination angle of an axis of the first forward pressing roller with respect to a butting direction of the first joining member within a plane perpendicular to a joining direction and an inclination angle of an axis of the second forward pressing roller with respect to the butting direction of the second joining member within a plane perpendicular to a joining direction based on a measured value of a characteristic concerning a joint state of a joined butted portion of the first and second joining members.

In this case, a poor junction prevention work can be performed efficiently. As a characteristic concerning the joint state of the joined butted portion, the surface temperature and its surface residual stress of the joined butted portion can be exemplified.

In the first or third aspect of the present invention, it is preferable that the first forward pressing roller and the second forward pressing roller are separate members, and that the joining of the butted portion is performed in a state in which an axis of at least one of rollers including the first forward pressing roller and the second forward pressing roller is inclined with respect to a butting direction of the joining members within a plane parallel to upper surfaces of the joining members so that force in a butting direction is given to the joining members.

In this case, since the first forward pressing roller and the second forward pressing roller are separate members, even if the thick dimension of at least one of the joining members fluctuates in a direction parallel to the joining direction, the joining members can be pressed firmly. Furthermore, by inclining the axis of at least one of rollers including the first forward pressing roller and the second forward pressing roller with respect to a butting direction of the joining members within a plane parallel to upper surfaces of the joining members so that force in a butting direction is given to the joining members, both the joining members come to stick strongly at the butted portion. Thus, by joining the butted portion in this state of this adhesion, the joining members can be joined firmly at the butted portion.

In any one of the aforementioned first to third aspects of the present invention, it is preferable that the joining of the butted portion is performed in a state in which the joining-direction forward sides of the first joining member and the second joining member with respect to a probe inserted position is supported from lower surface sides thereof by a first forward supporting roller and a second forward supporting roller separated from the first forward supporting roller, respectively, and an axis of at least one of rollers including the first forward supporting roller and the second forward supporting roller is inclined with respect to a butting direction of the joining members within a plane parallel to lower surfaces of the joining members so that force in a butting direction is given to the joining members.

In this case, both the joining members come to stick strongly at the butted portion. Thus, by joining the butted portion in this state of this adhesion, the joining members can be joined firmly at the butted portion.

In any one of the aforementioned first to third aspects of the present invention, it is preferable that the joining of the butted portion is performed in a state in which the joining-direction backward sides of the first joining member and the second joining member with respect to a probe inserted position is supported from lower surface sides thereof by a first backward supporting roller and a second backward supporting roller separated from the first backward supporting roller, respectively.

In this case, by using a backward supporting roller divided into the first backward supporting roller and the second backward supporting roller, the design freedom of the backward supporting roller increases. Accordingly, for example, by changing the mutual arrangement of the first backward supporting roller or the second backward supporting roller or changing the circumferential speed thereof, a meandering movement of the joining members which may be generated at the time of the movement of the joining members can be prevented, and the straightening effect to the configuration defect of each joining member can be expected.

In any one of the aforementioned first to third aspects of the present invention, it is preferable that the joining of the butted portion is performed in a state in which tension in a direction parallel to a joining direction is given to at least one of the first joining member and the second joining member.

In this case, configuration defects, such as curvature, twist and deflection, can be corrected, and surface vibration of each joining member can be suppressed. By joining the butted portion in this state, the quality of the butted joining members to be obtained can be improved.

In any one of the aforementioned first to third aspects of the present invention, it is preferable that the joining of the butted portion is performed while heating a lower surface of a probe inserted position of the butted portion or a lower surface of a joining-direction forward side of the probe inserted position.

In this case, heat conducts in the thickness direction from the lower surface of both the joining members, and the portion near the lower surface in the thickness direction becomes high in temperature. Accordingly, the materials between the tip of the probe and the lower surface of the joining members can be softened quickly at the time of joining, preventing the generation of the root remaining portion, which results in increased joining strength.

As a heating apparatus for heating the lower surface of both the joining members, a heating roller having a heated periphery to be contacted to the lower surface of the probe inserted position or the lower surface of the joining-direction forward side of the probe inserted position at the butted portion of the joining members, a laser irradiation heating apparatus, or a high frequency induction heating apparatus can be used suitably. Furthermore, in cases where at least one of the joining members is made of an aluminum or its alloy, it is especially preferable that the lower surface is heated such that the temperature of the lower surface falls within the range of from 400 to 500° C.

In any one of the aforementioned first to third aspects of the present invention, it is preferable that the joining of the butted portion is performed while relatively moving the first and second joining members with respect to a rotating sub-probe of a sub-joining tool inserted into the butted portion of the first and second joining members or a joined butted portion from a lower surface side thereof so that the probe and the sub-probe advance along the butted portion.

In this case, the butted portion is joined while the root remaining portion is joined by the sub-probe of the sub-joining tool. Accordingly, the generation of root remaining portion can be prevented (suppressed), and the joining strength can be improved.

It is preferable that the insertion depth of the sub-probe of the sub-joining tool into the butted portion or the joined butted portion from the lower surface thereof falls within the range of from 0.1 to 0.5 mm. The reasons are as follows. If the insertion depth is less than 0.1 mm, there is a possibility that the insertion depth may be insufficient and therefore the root remaining portion may remain. On the other hand, if the insertion depth exceeds 0.5 mm, the force required for moving both the joining members becomes large, and therefore it becomes difficult to move the joining members. Accordingly, it is preferable that the insertion depth falls within the range of from 0.1 to 0.5 mm. Furthermore, it is especially preferable that the insertion depth is set so as to fall within the aforementioned range in cases where the two joining members are different in wall thickness and the wall thickness of the thinner joining member is 3 mm or less. Furthermore, it is also especially preferable to set the insertion depth to the aforementioned range in cases where the wall thickness of two joining members is the same and 3 mm or less.

In order to attain the aforementioned second object, according to the fourth aspect of the present invention, in a friction agitation joining method for joining a first joining member and a second joining member butted against each other by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from upper surface sides thereof so that the probe advances along the butted portion, the joining of the butted portion is performed while heating a lower surface of a probe inserted position of the butted portion or a lower surface of a joining-direction forward side of the probe inserted position.

In the friction agitation joining method according to the fourth aspect of the present invention, heat conducts in the thickness direction from the lower surface of both the joining members, and the portion near the lower surface in the thickness direction becomes high in temperature. Accordingly, the materials between the tip of the probe and the lower surface of the joining members can be softened quickly at the time of joining, preventing the generation of the root remaining portion, which results in increased joining strength.

As a heating apparatus for heating the lower surface of both the joining members, the aforementioned heating roller, a laser irradiation heating apparatus, or a high frequency induction heating apparatus can be used suitably. Furthermore, in cases where at least one of the joining members is made of an aluminum or its alloy, it is especially preferable that the lower surface is heated such that the temperature of the lower surface falls within the range of from 400 to 500° C. Furthermore, in this fourth aspect of the present invention, the wall thickness of the two joining members may be the same or different with each other. Furthermore, the two joining members may be arranged such that the level difference is formed at the upper surface side of both the joining members. Alternatively, they may be arranged such that the level difference is not formed at the upper surface side thererof.

In the aforementioned fourth aspect of the present invention, it is preferable that the heating is performed by heat conduction from a heated periphery of a backing roller disposed opposite to the probe at a lower surface side of the joining members.

In this case, the heated periphery of the backing roller is contacted to the lower surface of the probe insertion position of the butted portion of the joining members at the time of joining. Thereby, the heat of the periphery of the backing roller conducts at the lower surfaces of the joining members, and therefore the lower surfaces are heated. Thus, the butted portion is joined while being heated. Accordingly, the joining operation can be performed efficiently. Furthermore, since the lower surface of the probe inserted position at the butted portion of the joining members is heated, the heat loss is small, and therefore the heating can be performed efficiently.

In order to attain the aforementioned second object, according to the fifth aspect of the present invention, in a friction agitation joining method for joining a first joining member and a second joining member butted against each other with upper and lower surfaces being flush with each other by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from upper surface sides thereof so that the probe advances along the butted portion, the joining of the butted portion is performed while relatively moving the first and second joining members with respect to a rotating sub-probe of a sub-joining tool inserted into the butted portion of the first and second joining members or a joined butted portion from a lower surface side thereof so that the probe and the sub-probe advance along the butted portion.

In this case, the butted portion is joined while the root remaining portion is joined by the sub-probe of the sub-joining tool. Accordingly, the generating of root remaining portion can be prevented (suppressed), and the joining strength can be improved.

In the aforementioned fifth aspect of the present invention, it is preferable that an insertion depth of the sub-probe is regulated within the range of from 0.1 to 0.5 mm. The reasons have been mentioned above. Furthermore, in cases where the thickness of the joining member is 3 mm or less, it is preferable that the insertion depth of the sub-probe is set so as to fall within the aforementioned range.

In order to attain the aforementioned first object, according to the sixth aspect of the present invention, in method for manufacturing joined butted members by performing a friction agitation joining method for joining a first joining member and a second joining member butted against each other with a level difference formed at upper surface sides thereof by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from the upper surface sides so that the probe advances along the butted portion, joining of the butted portion is performed while pressing joining-direction forward sides of the first joining member and the second joining member with respect to a probe inserted position from the upper surface sides by a first forward pressing roller and a second forward pressing roller, respectively.

According to the method of the sixth aspect of the present invention, the same function as in the first aspect of the present invention can be obtained.

In order to attain the aforementioned first object, according to the seventh aspect of the present invention, in a method for manufacturing joined butted member by performing a friction agitation joining method for joining a first joining member and a second joining member butted against each other with a level difference formed at upper surface sides thereof by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from the upper surface sides so that the probe advances along the butted portion, joining of the butted portion is performed while pressing joining-direction backward sides of the first joining member and the second joining member with respect to a probe inserted position from the upper surface sides by a first backward pressing roller and a second backward pressing roller, respectively.

According to the method of the seventh aspect of the present invention, the same function as in the second aspect of the present invention can be obtained.

In order to attain the aforementioned first object, according to the eighth aspect of the present invention, in a method for manufacturing joined butted members by performing a friction agitation joining method for joining a first joining member and a second joining member butted against each other with a level difference formed at upper surface sides thereof by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from the upper surface sides so that the probe advances along the butted portion, joining of the butted portion is performed while pressing joining-direction forward sides of the first joining member and the second joining member with respect to a probe inserted position from the upper surface sides by a first forward pressing roller and a second forward pressing roller, respectively, and pressing joining-direction backward sides of the first joining member and the second joining member with respect to a probe inserted position from the upper surface sides by a first backward pressing roller and a second backward pressing roller, respectively.

According to the method of the eighth aspect of the present invention, the same function as in the third aspect of the present invention can be obtained.

In any one of the aforementioned sixth to eighth aspects of the present invention, it is preferable that the joining of the butted portion is performed while heating a lower surface of a probe inserted position of the butted portion or a lower surface of a joining-direction forward side of the probe inserted position.

In this case, the generating of the root remaining portion can be prevented, and the joining strength can be improved.

In any one of the aforementioned sixth to eighth aspects of the present invention, it is preferable that the joining of the butted portion is performed while relatively moving the first and second joining members with respect to a rotating sub-probe of a sub-joining tool inserted into the butted portion of the first and second joining members or a joined butted portion from a lower surface side thereof so that the probe and the sub-probe advance along the butted portion.

In this case, the generating of the root remaining portion can be prevented, and the joining strength can be improved.

In order to attain the aforementioned second object, according to the ninth aspect of the present invention, in a method for manufacturing joined butted members by performing a friction agitation joining method for joining a first joining member and a second joining member butted against each other by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from upper surface sides thereof so that the probe advances along the butted portion, the joining of the butted portion is performed while heating a lower surface of a probe inserted position of the butted portion or a lower surface of a joining-direction forward side of the probe inserted position.

In this case, the generating of the root remaining portion can be prevented, and the joining strength can be improved.

In order to attain the aforementioned second object, according to the tenth aspect of the present invention, in a method for manufacturing joined butted members by performing a friction agitation joining method for joining a first joining member and a second joining member butted against each other with upper and lower surfaces being flush with each other by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from upper surface sides thereof so that the probe advances along the butted portion, the joining of the butted portion is performed while relatively moving the first and second joining members with respect to a rotating sub-probe of a sub-joining tool inserted into the butted portion of the first and second joining members or a joined butted portion from a lower surface side thereof so that the probe and the sub-probe advance along the butted portion.

In this case, the generating of the root remaining portion can be prevented, and the joining strength can be improved.

In order to attain the aforementioned first object, according to the eleventh aspect of the present invention, a friction agitation joining apparatus for joining a first joining member and a second joining member butted against each other with a level difference formed at upper surface sides thereof by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from the upper surface sides so that the probe advances along the butted portion, comprises: a first forward pressing roller for pressing joining-direction forward side of the first joining member with respect to a probe inserted position from upper surface side thereof; and a second forward pressing roller for pressing joining-direction forward side of the second joining member with respect to the probe inserted position from upper surface side thereof.

With the friction agitation joining apparatus according to the eleventh aspect of the present invention, the friction agitation joining method according to the first aspect of the present invention or the method for manufacturing joined butted members according to the sixth aspect of the present invention can be performed efficiently.

In order to attain the aforementioned first object, according to the twelfth aspect of the present invention, a friction agitation joining apparatus for joining a first joining member and a second joining member butted against each other with a level difference formed at upper surface sides thereof by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from the upper surface sides so that the probe advances along the butted portion, comprises: a first backward pressing roller for pressing joining-direction backward side of the first joining member with respect to a probe inserted position from upper surface side thereof; and a second backward pressing roller for pressing joining-direction backward side of the second joining member with respect to the probe inserted position from upper surface side thereof.

With the friction agitation joining apparatus according to the twelfth aspect of the present invention, the friction agitation joining method according to the second aspect of the present invention or the method for manufacturing joined butted members according to the seventh aspect of the present invention can be performed efficiently.

In order to attain the aforementioned first object, according to the thirteenth aspect of the present invention, a friction agitation joining apparatus for joining a first joining member and a second joining member butted against each other with a level difference formed at upper surface sides thereof by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from the upper surface sides so that the probe advances along the butted portion, comprises: a first forward pressing roller for pressing joining-direction forward side of the first joining member with respect to a probe inserted position from upper surface side thereof; and a second forward pressing roller for pressing joining-direction forward side of the second joining member with respect to the probe inserted position from upper surface side thereof; a first backward pressing roller for pressing joining-direction backward side of the first joining member with respect to a probe inserted position from upper surface side thereof; and a second backward pressing roller for pressing joining-direction backward side of the second joining member with respect to the probe inserted position from upper surface side thereof.

With the friction agitation joining apparatus according to the thirteenth aspect of the present invention, the friction agitation joining method according to the third aspect of the present invention or the method for manufacturing joined butted members according to the eighth aspect of the present invention can be performed efficiently.

In any one of the aforementioned eleventh to thirteenth aspects of the present invention, it is preferable to further comprise a third backward pressing roller having a tapered periphery for pressing a joined butted portion of the joining members from surface sides thereof.

It is preferable that the periphery of the third backward pressing roller is cooled.

In any one of the aforementioned eleventh to thirteenth aspects of the present invention, it is preferable to further comprise a cooling roller for cooling a lower surface of a joined butted portion of the first and second joining members by keeping a cooled periphery of the cooling roller in contact with the lower surface.

In any one of the aforementioned eleventh to thirteenth aspects of the present invention, it is preferable that the first forward pressing roller and the second forward pressing roller are separate members, and further comprising an inclination angle changing apparatus for changing an inclination angle of an axis of at least one of rollers including the first forward pressing roller and the second forward pressing roller with respect to a butting direction of the joining members within a plane perpendicular to a joining direction.

Furthermore, it is preferable to further comprise a measuring device for measuring a characteristic concerning a joint state of a joined butted portion of the joining members, and a controller for controls an operation of the inclination angle changing apparatus based on a measured value obtained by the measuring device.

In any one of the aforementioned eleventh to thirteenth aspects of the present invention, it is preferable that the first forward pressing roller and the second forward pressing roller are separate members, and further comprising an inclination angle changing apparatus for changing an inclination angle of an axis of at least one of rollers including the first forward pressing roller and the second forward pressing roller with respect to a butting direction of the joining members within a plane parallel to upper surfaces of the joining members.

In any one of the aforementioned eleventh to thirteenth aspects of the present invention, it is preferable to further comprise a measuring device for measuring a characteristic concerning a joint state of a joined butted portion of the joining members, and a controller for controls an operation of the inclination angle changing apparatus based on a measured value obtained by the measuring device.

In any one of the aforementioned eleventh to thirteenth aspects of the present invention, it is preferable to further comprise a first forward supporting roller for supporting the joining-direction forward side of the first joining member with respect to a probe inserted position from a lower surface side thereof, a second forward supporting roller for supporting the joining-direction forward side of the second joining member with respect to a probe inserted position from a lower surface side thereof, the second forward supporting roller being separated from the first forward supporting roller, and an inclination angle changing apparatus for changing an inclination angle of an axis of at least one of rollers including the first forward supporting roller and the second forward supporting roller with respect to a butting direction of the joining members within a plane parallel to lower surfaces of the joining members.

In any one of the aforementioned eleventh to thirteenth aspects of the present invention, it is preferable to further comprise a first backward supporting roller for supporting the joining-direction backward side of the first joining member with respect to a probe inserted position from a lower surface side thereof, and a second backward supporting roller for supporting the joining-direction forward side of the second joining member with respect to a probe inserted position from a lower surface side thereof, the second backward supporting roller being separated from the first backward supporting roller.

In any one of the aforementioned eleventh to thirteenth aspects of the present invention, it is preferable to further comprise a tension device for giving tension in a direction parallel to a joining direction to at least one of the first joining member and the second joining member.

In any one of the aforementioned eleventh to thirteenth aspects of the present invention, it is preferable to further comprise a heating device for heating a lower surface of a probe inserted position of the butted portion or a lower surface of a joining-direction forward side of the probe inserted position.

In any one of the aforementioned eleventh to thirteenth aspects of the present invention, it is preferable to further comprise a sub-joining tool having a rotatable sub-probe, wherein the rotating sub-probe is inserted into the butted portion or a joined butted portion when the butted portion is joined or is being joined to join a root remaining portion produced at the joined butted portion of the joining members.

In order to attain the aforementioned second object, according to the fourteenth aspect of the present invention, a friction agitation joining apparatus for joining a first joining member and a second joining member butted against each other by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from the upper surface sides so that the probe advances along the butted portion, comprises a heating device for heating a lower surface of a probe inserted position of the butted portion or a lower surface of a joining-direction forward side of the probe inserted position.

With the friction agitation joining apparatus according to the fourteenth aspect of the present invention, the friction agitation joining method according to the fourth aspect of the present invention or the method for manufacturing joined butted members according to the ninth aspect of the present invention can be performed efficiently.

In order to attain the aforementioned second object, according to the fifteenth aspect of the present invention, a friction agitation joining apparatus for joining a first joining member and a second joining member butted against each other with upper and lower surfaces being flush with each other by relatively moving the first and second joining members with respect to a rotating probe of a joining tool inserted into a butted portion of the first and second joining members from upper surface sides thereof so that the probe advances along the butted portion, comprises a sub-joining tool having a rotatable sub-probe, wherein the rotating sub-probe is inserted into the butted portion or a joined butted portion when the butted portion is joined or is being joined to join a root remaining portion produced at the joined butted portion of the joining members.

With the friction agitation joining apparatus according to the fifteenth aspect of the present invention, the friction agitation joining method according to the fifth aspect of the present invention or the method for manufacturing joined butted members according to the tenth aspect of the present invention can be performed efficiently.

In the present invention, the language “upper surface side” means a side from which a (main) rotating probe is inserted, and “lower surface side” means a side opposite to the “upper surface side”, i.e., a side opposite to the side from which a (main) rotating probe is inserted.

BEST MODE FOR CARRYING OUT THE INVENTION

In order to explain the present invention in detail, the preferred six embodiments according to the present invention will be explained with reference to the attached drawings.

First Embodiment

FIGS. 1 to 7are drawings for explaining a friction agitation joining method, a method for manufacturing of butted joining members and a friction agitation joining apparatus according to the first embodiment of the present invention.FIG. 1is a side view showing the state in the middle of joining the butted portion of both the joining members by the friction agitation joining method.FIG. 2is an enlarged perspective view showing the Z portion inFIG. 1.

InFIG. 2, “1” denotes a thin and long plate-shaped first joining member, and “2” denotes a thick and long plate-shaped second joining member. Each of these joining members1and2is made of aluminum or its alloy. In this figure, “80” denotes a friction agitation joining apparatus according to the first embodiment. The butted joining members obtained by the friction agitation joining method is used as, for example, tailored blank materials for automobiles.

Each joining member1and2has an upper surface and a lower surface parallel with each other as shown inFIG. 4, and the corresponding widthwise side edges are to be butted against each other. This widthwise side edge is formed to be perpendicular to the upper and lower surfaces of the joining member. The width wise side edges of these two joining members1and2are butted against each other with the lower surfaces of the joining members being flush with each other (“3” denotes the butted portion). Accordingly, a stepped portion corresponding to the thickness difference is formed at the upper surface side of the joining members. “4” denotes a stepped portion formed on the upper surfaces of the joining members1and2. “4a” denotes the corner portion of this stepped portion4. Furthermore, “N” denotes a butting direction of each joining member1and2. This butting direction N is parallel to the width direction of the joining member.

As shown inFIG. 2, in this butted state, both the joining members1and2are supported by the support members30in a horizontal state. In this first embodiment, a forward supporting roller31and a backward supporting roller32are used as a supporting member30.

Furthermore, as shown inFIG. 1, each joining member1and2is pulled in the longitudinal direction by forward tension rollers70and backward tension rollers70equipped to a tension leveler as a tension device in the state in which each joining member is supported by the supporting members30. Thereby, tension in the longitudinal direction is given to each joining member1and2.

InFIG. 2, “40” denotes a joining tool for friction agitation joining. This joining tool40is equipped with a columnar rotor41having a larger diameter and a pin-shaped probe42having a smaller diameter. The probe42is projected from the rotational center of the end face41aof the rotor41along the rotation axis Q. InFIG. 2, this probe42of the joining tool40, which is rotating about the rotation axis Q, is inserted into the butted portion3of the joining members1and2from the upper surface side of the joining members. In this inserted state, as shown inFIG. 5, the rotation axis Q of the rotor41and the probe42is arranged in the state in which the rotation axis Q is inclined toward the first joining member1(namely, the joining member at the lower level side). The end face41aof the rotor41is disposed in the state in which the end face41ais pressed against the shoulder portion2aof the second joining member2(namely, the shoulder portion of the joining member at the higher level) projected from the butted portion3. InFIG. 5, “T” denotes a normal line of the surface at the probe inserted position of the joining members. “θ” denotes the inclination angle of the rotation axis Q toward the first joining member1with respect to the aforementioned “T.”

In this joining tool40, both of the rotor41and the probe42are made of heat-resisting materials that is harder than the joining members1and2and that can bear frictional heat generated at the time of joining. On the periphery of the probe42, agitating protrusions (not shown) for agitating the materials of the joining members1and2softened by frictional heat are formed in a spiral manner or the like.

InFIG. 5, “D” denotes the diameter of the end face41aof the rotor41. At least the peripheral edge of the end face41aof this rotor41is formed within a plane perpendicular to the rotation axis Q. In this first embodiment, the end face41aof the rotor41is a flat surface. In addition, in the present invention, although it is not illustrated, the end face41aof the rotor41may be formed into a configuration depressing toward the center of the rotation from the peripheral edge thereof.

In this first embodiment, as shown inFIG. 2, the butted portion3of both the joining members1and2are to be joined by moving the joining members1and2in one longitudinal direction thereof (the moving direction is shown as “MD”) in a state in which the probe42is inserted from the upper surface side into the butted portion3as mentioned above and the tension in the longitudinal direction of the joining members1and2is given to both the joining members1and2so that the probe42advances the butted portion3. Accordingly, in this first embodiment, the joining direction WD coincides with a direction opposite to the moving direction MD of the joining members1and2. Furthermore, the longitudinal direction of each joining member1and2coincides with a direction parallel to the joining direction WD. InFIG. 2, “3′” denotes the joined butted portion of the joining members1and2joined by the probe42. “W” denotes a joined portion formed in the joined butted portion3′.

At the time of joining, as shown inFIG. 3, the rotation axis Q of the joining tool40is slightly inclined toward the joining-direction backward side. Thereby, the joining-direction forward side of the end face41aof the rotor41is lifted up from the upper surface of the joining members1and2. This prevents the joining-direction forward side of the end face41aof the rotor41from being caught by the minute unevenness which may exist on the upper surface of the joining members1and2, resulting in a smooth advancing movement of the probe42along the butted portion3.

Next, the structure of the friction agitation joining apparatus80according to the first embodiment will be explained. InFIG. 2, “33” denotes a backing roller. This backing roller33has a columnar-shape having a predetermined length. This backing roller33is disposed at the lower surface side of the joining members1and2such that the roller is opposed to the probe42of the joining tool40and bridges over both the joining members1and2. By this backing roller33, joining members1and2are supported at the lower surface of the probe inserted position of the butted portion3. This backing roller33also plays a role for supporting both the joining members1and2as a supporting member30.

The support member30is equipped with the forward supporting roller31and the backward supporting roller32. The forward supporting roller31is a column-shaped member having a predetermined length. Similarly, the backward supporting roller32is a column-shaped member having a predetermined length. At the joining-direction forward side of the joining members1and2with respect to the probe inserted position, the forward supporting roller31is disposed at the lower surface side of the joining members1and2in a state in which the axis of the roller31is parallel to the butting direction N and the roller31bridges over both the joining members1and2. Similarly, at the joining-direction backward side of the joining members1and2with respect to the probe inserted position, the backward supporting roller32is disposed at the lower surface side of the joining members1and2in a state in which the axis of the roller32is parallel to the butting direction N and the roller32bridges over both the joining members1and2. By these forward supporting roller31and the backward supporting roller32, both the joining members1and2are supported from the lower surface side thereof at the joining-direction forward side and the joining-direction backward side of the joining members1and2with respect to the probe inserted position.

The forward supporting roller31, the backward supporting roller32and the backing roller33are connected to a rotation driving device (not shown). By operating this rotation driving device, these rollers31,32and33are rotated about the axis thereof at a constant circumferential speed at a fixed position, respectively. Accordingly, these rollers31,32and33also function as driving rollers for moving the joining members1and2in a prescribed direction MD. In the present invention, the backing roller33may be rotated freely. Furthermore, the forward and backward supporting rollers31and32may be rotated freely in cases where a driving device for moving the joining members1and2in the predetermined direction MD is provided separately.

Furthermore, the backward supporting roller32also functions as a cooling roller. That is, at the peripheral surface portion of the backward supporting roller31, a plurality of coolant circulation passages35arranged in the circumferential direction thereof are provided. Each passage extends in the longitudinal direction of the roller32. The coolant (e.g., cooling water) is circulating in these coolant circulation passages35. Thereby, the peripheral portion of the backward supporting roller32is in a cooled state. At the time of supporting the joining members1and2, the cooled peripheral portion of the backward supporting roller32comes into contact with the lower surface of the joined butted portion3′, to thereby cool the joined butted portion3′ from the lower surface thereof.

InFIG. 2, “11” denotes a first forward pressing roller. “12” denotes a second forward pressing roller. The first forward pressing roller11is a rotatable columnar-shaped member having a larger diameter and a predetermined length. The second forward pressing roller12is a rotatable columnar-shaped member having a smaller diameter and a predetermined length. As shown inFIGS. 2 and 4, at the upper surface side of the first joining member1, the first forward pressing roller11is disposed above the forward supporting roller31in a state in which the axis P1of the roller11is parallel to the butting-direction N of the first joining member1at the joining-direction forward side of the first joining member1with respect to the probe inserted position. Similarly, at the upper surface side of the second joining member2, the second forward pressing roller12is disposed above the forward supporting roller31in a state in which the axis P2of the roller12is parallel to the butting-direction N of the second joining member2at the joining-direction forward side of the second joining member2with respect to the probe inserted position.

In this first embodiment, the first forward pressing roller11and the second forward pressing roller12are integrally connected in a state in which the axes thereof are arranged on the same straight-line and the end faces thereof are butted against each other. This integrated roller10is referred to as “forward pressing roller” in this first embodiment.

In this forward pressing roller10, the difference between the radius of the first forward pressing roller11and that of the second pressing roller12coincides with the level difference formed on the upper surface of the joining members1and2(namely, the height-difference between the upper surface of the first joining member1and that of the second joining member2).

By the first forward pressing roller11, the area at the joining-direction forward side of the first joining member1covering from the widthwise intermediate portion of the first joining member1to the portion near the butted portion3is pressed downwardly from the upper surface side. Similarly, by the second forward pressing roller12, the area at the joining-direction forward side of the first joining member2covering from the widthwise intermediate portion of the second joining member2to the portion near the butted portion3is pressed downwardly from the upper surface side.

Since the forward pressing rollers10presses these joining members1and2, the lower surfaces of the joining members1and2are pressed against the periphery of the forward supporting roller31. Thereby, driving force in the moving direction MD can be given to the joining members1and2. On the other hand, in accordance with the movement of these joining member1and2, the first and second forward pressing rollers11and12integrally rotate about the axis P1and P2at a predetermined position.

InFIG. 2, “21” and “22” denote a first backward pressing roller and a second backward pressing roller, respectively. The first backward pressing roller21is a rotatable column-shaped member having a larger diameter and a predetermined length. The second backward pressing roller22is a rotatable column-shaped member having a smaller diameter and a predetermined length.

As shown inFIGS. 2 and 7, at the upper surface side of the first joining member1, the first backward pressing roller21is disposed above the backward supporting roller32in a state in which the axis of the roller21is parallel to the butting-direction N of the first joining member1at the joining-direction backward side of the first joining member1with respect to the probe inserted position. Similarly, at the upper surface side of the second joining member2, the second backward pressing roller22is disposed above the backward supporting roller32in a state in which the axis of the roller22is parallel to the butting-direction N of the second joining member2at the joining-direction backward side of the second joining member2with respect to the probe inserted position. InFIG. 2, “23” is a third backward pressing roller. This third backward pressing roller23is a rotatable truncated cone-shaped member, and therefore the peripheral surface thereof is a tapered surface. This third backward pressing roller23is used for pressing the joined butted portion3′ of the joining members1and2from the upper surface thereof. At the upper surface side of the joining members1and2, the third backward pressing roller23is disposed above the backward supporting roller32in a state in which the axis of the roller23is parallel to the butting-direction N of the joining members1or2.

In this first embodiment, the first backward pressing roller21, the third backward pressing roller23and the second backward pressing roller22are integrally connected in a state in which the axes are arranged on the same straight line in this order and adjacent end faces are butted against each other. This integrated roller20is referred to as a “backward pressing roller” in the first embodiment.

In this backward pressing roller20, the difference between the radius of the first backward pressing roller21and the second backward pressing roller22coincides with the level difference formed on the upper surfaces of the joining members1and2. Furthermore, the periphery of the first backward pressing roller21and the periphery of the second backward pressing roller22are continuously connected via the periphery (namely, tapered surface) of the third backward pressing roller23.

By the first backward pressing roller21, the area at the joining-direction backward side of the first joining member1covering from the widthwise intermediate portion of the first joining member1to the portion near the joined butted portion3′ is pressed downwardly from the upper surface side. Similarly, by the second backward pressing roller22, the area at the joining-direction backward side of the second joining member2covering from the widthwise intermediate portion of the second joining member2to the portion near the joined butted portion3′ is pressed downwardly from the upper surface side.

Furthermore, at the peripheral surface portion of the third backward pressing roller23, as shown inFIG. 2, a plurality of coolant circulation passages25arranged in the circumferential direction thereof are provided. Each passage extends in the longitudinal direction of the roller23so as to penetrate the first backward pressing roller21and the second backward pressing roller22. The coolant (e.g., cooling water) is circulating in these coolant circulation passages25. Thereby, the peripheral portion of the third backward pressing roller23is in a cooled state. At the time of pressing the joined butted portion3′, the cooled peripheral portion of the third backward pressing roller23comes into contact with the upper surface of the joined butted portion3′, to thereby cool the joined butted portion3′ from the upper surface thereof.

Since the backward pressing roller20presses these joining members1and2, the lower surfaces of the joining members are pressed against the periphery of the backward supporting roller32. Thereby, driving force in the moving direction MD can be given to the joining members1and2. On the other hand, in accordance with the movement of these joining member1and2, the first to third backward pressing rollers21,22and23integrally rotate about the axis at a predetermined position.

Next, the joining steps of the friction agitation joining method of the first embodiment will be explained.

First, tension in a direction parallel to the joining direction (i.e., the longitudinal direction) is given to each joining member1and2by tension rollers70and70. This corrects the twist, curvature and deflection of each joining member1and2, and suppresses the surface vibration of each joining member1and2. The tension may be given during the joining process.

Furthermore, an area of the joining-direction forward side of the first joining member1covering from the widthwise intermediate portion thereof to a portion near the butted portion3is pressed by the first forward pressing roller11from the upper surface side, and an area of the joining-direction forward side of the second joining member2covering from the widthwise intermediate portion thereof to a portion near the butted portion3is pressed by the second forward pressing roller12from the upper surface side.

The torsion of each joining member1and2is further corrected by being pressed as mentioned above, causing an adhesion of the butted portion3of the joining members1and2. As a result, no clearance will be generated at the butted portion3. Thus, both the joining members1and2are moved by receiving the driving force of the forward supporting roller31in the adhered state.

At certain timing, the probe42is rotated by rotating the rotor41of the joining tool40. Then, the rotating probe42is inserted into the butted portion3of the joining members1and2from the upper surface side of thereof with the rotation axis Q inclined toward the first joining member side1. Furthermore, the end face41aof the rotor41is pushed against the shoulder portion2aof the second joining member2. The insertion of the probe42into the butted portion3may be performed from a longitudinal end of the joining members1and2. Furthermore, inclining the rotation axis Q toward the first joining member side1may be performed after the insertion of the probe42into the butted portion3.

Due to the frictional heat generated in accordance with the rotation of the probe42and the frictional heat generated by the mutual contact between the end face41aof the rotor41and the shoulder portion2aof the second joining member2, the probe-inserted portion of the butted portion3of the joining members1and2and therearound are softened, the shoulder portion2aof the second joining member2is plastically deformed into an inclined surface by being pressed by the end surface41aof the rotor41. Furthermore, due to this plastic deformation, a part of the materials of the shoulder portion2ais filled in the corner portion4aof the stepped portion4.

The materials of the joining members1and2softened by the frictional heat is agitated and mixed by the rotational force of the probe42while the corner portion4ais being filled up with a part of the materials of the shoulder portion2a. In accordance with the advance movement of the joining members1and2, the softened materials are plastically fluidized to go around the probe42to fill up a groove formed behind the advancing probe42. Then, the softened and agitated materials will be cooled and solidified by the immediate loss of the friction heat. Thus, the butted portion3of the joining members1and2is joined as the probe42advances. At this time, as mentioned above, the rotation axis Q of the joining tool40is inclined toward the first joining member side1, and a part of the materials of the shoulder portion2aof the second joining member2fills the corner portion4a. Therefore, the surface of the joined butted portion3′ is formed into an inclined surface bridging the surface of the first joining member1and that of the second joining member2, as shown inFIG. 6. As shown inFIG. 6, the minute unevenness such as burrs are formed on the surface of the joined butted portion3′.

While joining the butted portion3with the probe42in this way, the joining members1and2are moved and introduced between the backward supporting roller32and the first to third pressing rollers21,22and23. Then, an area of the joining-direction backward side of the first joining member1with respect to the probe-inserted position covering from the widthwise intermediate portion to a portion near the joined butted portion3′ is pressed by the first backward pressing roller21from the upper surface side, and an area of the joining-direction backward side of the second joining member2with respect to the probe-inserted position covering from the widthwise intermediate portion to a portion near the joined butted portion3′ is pressed by the second backward pressing roller22from the upper surface side. Furthermore, the joined butted portion3′ is pressed by the third backward pressing roller23from the upper surface side.

In this way, both the joining members1and2are pressed by the backward pressing roller20. Thereby, the twist and curvature of each joining member1and2are further corrected. Furthermore, since the periphery of the third backward pressing roller23is formed into a tapered surface, when the joined butted portion3′ is pressed by this third backward pressing roller23, the joined butted portion3′ is pressurized. As a result, the surface is formed into a gentle inclined surface as shown inFIG. 7. At the same time, the minute unevenness formed on the upper surface of the joined butted portion3′ is pressed and removed. Thereby, the surface of the joined butted portion3′ is smoothed with the gently inclined state. Furthermore, when the joined butted portion3′ is pressed, the tensile residual stress produced on the surface of the joined butted portion3′ is converted into compression residual stress. Accordingly, the durability of the butted joining members to be obtained can be improved.

When the joining end scheduled portion of the butted portion3of the joining members1and2arrives the position of the probe42, the probe42is removed therefrom, and the joining is completed. Thus, desired joined butted joining members can be obtained by the aforementioned joining operation.

As shown inFIG. 7, where the width and the taper angle of the periphery of the third backward pressing roller23are “a” and φ, respectively, the width “a” is set to be larger than the diameter D of the end face41aof the rotor41of the joining tool40(namely, a>D), and the taper angle φ is set to be smaller than the inclination angle θ of the rotation axis Q to a normal line T toward the first joining member side1(namely, φ<θ). This setting makes it possible to assuredly form a desired inclined surface of the joined butted portion3′. Furthermore, the minute unevenness can be assuredly removed by being pressurized.

Furthermore, since the upper surface of the joined butted portion3′ comes into contact with the cooled periphery of the third backward pressing roller23, the joined butted portion3′ will be quenched from the upper surface. Accordingly, the joining strength improves, and furthermore superfluous heat, which may be sometimes generated in the joined butted portion3′, is removed, resulting in a good joining status. Furthermore, since the lower surface of the joined butted portion3′ comes into contact with the cooled periphery of the backward supporting roller32, the butted portion3′ will be also quenched from the lower surface. Accordingly, the joining strength further improves.

In the present invention, the diameter “b” of the backing roller33is set to be equal to the diameter D of the end face41aof the rotor41of the joining tool40or larger than D (namely, b≧D), where the diameter of the backing roller33is “b” (seeFIG. 3). By setting the diameter “b” as mentioned above, the materials of the joining members softened by the frictional heat can be received from the lower surface side assuredly.

In this friction agitation joining method, since the joining-direction forward side of each joining member1and2with respect to the probe inserted position is pressed and the joining-direction backward side of each joining member1and2with respect to the probe inserted position is pressed at the time of joining, the curvature and the torsion of each joining member1and2can be more assuredly corrected. Then, since the joining of the butted portion3is performed in this state, the generation of poor junction such as joining defect or thermal distortion can be prevented more assuredly. Furthermore, since the butted portion3is joined in a state in which a portion near the butted portion at the joining-direction forward side of each joining member with respect to the probe inserted position is being pressed, the end portion of each joining member to be butted against each other can be pressed firmly. Therefore, the generation of poor junction can be prevented more assuredly.

Moreover, since tension in a direction parallel to the joining direction WD is given to each joining member1and2, configuration defects, such as curvature, twist and deflection, can be corrected more assuredly, and surface vibration of each joining member1and2can be suppressed. Accordingly, the generation of poor junction can be prevented more assuredly.

Furthermore, in this friction agitation joining apparatus80, since the first forward pressing roller11and the second forward pressing roller12are integrally connected, the structure of the supporting jig for supporting these rollers can be simplified.

Furthermore, in the butted joining members joined by the friction agitation joining method, since the joined butted portion3′ is in a quenched state, high joining strength can be obtained. Moreover, since the upper surface of the joined butted portion3′ is formed into an inclined surface bridging over the surface of the first joining member1and that of the second joining member2, the obtained butted joining members can relieve the stress concentration produced in the stepped portion4. Accordingly, outstanding reliability in strength can be obtained.

Furthermore, since the upper surface of the joined butted portion3′ is smoothened in an inclined state by removing the minute unevenness such as burrs by pressing them, a good surface state can be obtained. Accordingly, even in cases where the upper surface of the butted joining members is painted, a film can be formed on the upper surface of the joined butted portion3′ in a good condition.

EXAMPLES

Next, concrete examples of the friction agitation joining method according to the first embodiment will be shown.

As a joining tool40, a tool having a rotor41with a probe41awas prepared. The diameter D of the end face41aof a rotor41was 9 mm, and the protrusion length of the probe42from the rotor end face41awas 2.3 mm. The probe42had an M3 screw axial portion.

As forward pressing rollers10, the rollers as shown inFIGS. 8A and 8Bwere prepared, while as backward pressing rollers20, the rollers as shown inFIGS. 8C to 8Ewere prepared. The structure of each roller was as follows.

The forward pressing roller10A shown inFIG. 8Ais the same column-shaped member as the conventional one, and is disposed so as to cover the butted portion.

The forward pressing roller10B shown inFIG. 8Bhas the same structure as the roller10of the first embodiment.

The backward pressing roller20C shown inFIG. 8Chas the same columnar-shape member as the conventional one.

The backward pressing roller20D shown inFIG. 8Dhas the same structure as the roller20of the first embodiment.

The backward pressing roller20E shown inFIG. 8Ecomprises a first backward pressing roller21, a second backward pressing roller22and a columnar connecting axial portion24having a diameter smaller than that of the second backward pressing roller22. The first backward pressing roller21and the second backward pressing roller22are integrally connected by the columnar connecting axial portion24. In other words, the backward pressing roller20E does not have a third backward pressing roller for pressing the joined butted portion3′. This backward pressing roller20E is arranged so that the first and second backward pressing rollers21and22are disposed besides the joined butted portion.

The side edge of the first joining member1and that of the second joining member2were butted against each other with the lower surfaces thereof being flush with each other. Then, the butted portion3was joined along the entire length thereof by the joining method of the first embodiment. In this joining, the roller10B shown inFIG. 8Bwas used as the forward pressing roller, and the roller20D shown inFIG. 8Dwas used as the backward pressing roller. The joining was performed under the following conditions: the rotating speed of the rotor41of joining tool40was 1,000 rpm; the joining rate was 700 mm/min; the inclination angle θ of the rotation axis Q of the joining tool40toward the first joining member1was 5°.

The forward pressing roller10B shown inFIG. 8Band the backward pressing roller20C shown inFIG. 8Cwere used. The butted portion3of the joining members1and2was joined along the entire length thereof. Other joining conditions were the same as the aforementioned example 1.

The forward pressing roller10A shown inFIG. 8Aand the backward pressing roller20D shown inFIG. 8Dwere used. The butted portion3of the joining members1and2was joined along the entire length thereof. Other joining conditions were the same as the aforementioned example 1.

The forward pressing roller10A shown inFIG. 8Aand the backward pressing roller20E shown inFIG. 8Ewere used. The butted portion3of the joining members1and2was joined along the entire length thereof. Other joining conditions were the same as the aforementioned example 1.

Comparative Example

The forward pressing roller10A shown inFIG. 8Aand the backward pressing roller20C shown inFIG. 8Cwere used. The butted portion3of the joining members1and2was joined along the entire length thereof. Other joining conditions were the same as the aforementioned example 1.

About the butted joining members obtained by the aforementioned examples 1–4 and the comparative example, the surface state of the joined butted portion was investigated with the naked eye, and the amount of thermal distortion was investigated.

About the amount of thermal distortion in Table 1, the amount of the maximum curvature of the obtained butted joining members disposed on a flat surface is shown as the amount of thermal distortion.

As shown in this table, in the butted joining members obtained by the comparative example, the amount of thermal distortion was 10 mm, and a large thermal distortion was generated. On the other hand, in the butted joining members obtained by the examples 1 to 4, the amount of thermal distortion was 5 mm or less, and the generation of thermal distortion was suppressed. Especially in the butted joining members of examples 1 and 2, the amount of thermal distortion was 3 mm, and the generation of thermal distortion was further suppressed.

Furthermore, in the butted joining members obtained by the comparative example, the non-joined portion was generated in the joined butted portion, and the poor joining was generated. On the other hand, in the butted joining members obtained by the examples 1 to 4, a non-joined portion was not generated, and the joining state was good.

Furthermore, in the butted joining members obtained by the examples 2, 4 and the comparative example, minute unevenness such as burrs were formed on the upper surface of the joined butted portion. To the contrary, in the butted joining members obtained by the examples 1 and 3, such minute unevenness was not formed on the upper surface of the joined butted portion. This surface was smoothened with an inclined state, and the surface state was very good.

Second Embodiment

FIGS. 9 to 16are drawings for explaining a friction agitation joining method, a method for manufacturing of butted joining members and a friction agitation joining method according to the second embodiment of the present invention. In these figures, the same reference numeral is allotted to the same component as in the aforementioned first embodiment. Hereinafter, this second embodiment will be explained by focusing on the differences between the first embodiment and the second embodiment.

In this second embodiment, as shown inFIG. 9, the forward pressing roller10is divided into the first forward pressing roller11and the second forward pressing roller12. That is, the first forward pressing roller11and the second forward pressing roller12are separate members. The outer diameter of first forward pressing roller11and that of the second forward pressing roller12have the same dimension.

InFIG. 9, “50” denotes a thermometry apparatus (e.g., radiation thermometer) for measuring the surface temperature of the joined butted portion3′ of the joining members1and2. This thermometry apparatus50is arranged between the probe inserted position at the upper surface side of the joining members1and2and the third backward pressing roller23.

InFIG. 10, “60a” is an inclination angle changing apparatus for the first forward pressing roller11. As shown inFIG. 11, this inclination angle changing apparatus60ais for changing the inclination angle α1of the axis P1of the first forward pressing roller11within a plane parallel to the upper surface of the first joining member1with respect to the butting-direction N of the first joining member1. Furthermore, as shown inFIG. 14, this inclination angle changing apparatus60aalso has a function for changing the inclination angle β1of the axis P1of the first forward pressing roller11within a plane perpendicular to the joining-direction WD with respect to the butting-direction N of the first joining member1. To this inclination angle changing apparatus60a, the first forward pressing roller11is connected. Therefore, by operating this inclination angle changing apparatus60a, the inclination angle α1and the inclination angle β1can be changed, respectively.

InFIG. 10, “61a” denotes a controller for the first forward pressing roller11. This controller61ais for controlling operation of the inclination angle changing apparatus60abased on the measured value obtained by the thermometry apparatus50, as shown inFIG. 11. To this controller61a, the thermometry apparatus50is connected. Furthermore, to this controller61a, the inclination angle changing apparatus60ais connected.

InFIG. 10, “60b” is an inclination angle changing apparatus for the second forward pressing roller12. As shown inFIG. 11, this inclination angle changing apparatus60bis for changing the inclination angle α2of the axis P2of the second forward pressing roller12within a plane parallel to the upper surface of the second joining member2with respect to the butting-direction N of the second joining member2. Furthermore, as shown inFIG. 14, this inclination angle changing apparatus60balso has a function for changing the inclination angle β2of the axis P2of the second forward pressing roller12within a plane perpendicular to the joining-direction WD with respect to the butting-direction N of the second joining member2. To this inclination angle changing apparatus60b, the second forward pressing roller12is connected. Therefore, by operating this inclination angle changing apparatus60b, the inclination angle α2and the inclination angle β2can be changed, respectively.

InFIG. 10, “61b” denotes a controller for the second forward pressing roller12. This controller61bis for controlling operation of the inclination angle changing apparatus60bbased on the measured value obtained by the thermometry apparatus50, as shown inFIG. 11. To this controller61b, the thermometry apparatus50is connected. Furthermore, to this controller61b, the inclination angle changing apparatus60bis connected.

In this friction agitation joining apparatus80, as shown inFIG. 9, the forward supporting roller31is divided into the first forward supporting roller31aand the second forward supporting roller31b. That is, the first forward supporting roller31aand the second forward supporting roller31bare separate members. The outer diameter of first forward supporting roller31aand that of the second forward supporting roller31bhave the same dimension. By the first forward supporting roller31a, the joining-direction forward side of the first joining member1relative to the probe inserted position is supported from the lower surface. Furthermore, by the second forward supporting roller31b, the joining-direction forward side of the second joining member2relative to the probe inserted position is supported from the lower surface.

InFIG. 10, “65a” is an inclination angle changing apparatus for the first forward supporting roller31a. As shown inFIG. 12, this inclination angle changing apparatus65ais for changing the inclination angle γ1of the axis S1of the first forward supporting roller31awithin a plane parallel to the lower surface of the first joining member1with respect to the butting-direction N of the first joining member1. To this inclination angle changing apparatus65a, the first forward supporting roller31ais connected. Therefore, by operating this inclination angle changing apparatus65a, the inclination angle γ1can be changed.

InFIG. 10, “65b” is an inclination angle changing apparatus for the second forward supporting roller31b. As shown inFIG. 12, this inclination angle changing apparatus65bis for changing the inclination angle γ2of the axis S2of the second forward supporting roller31bwithin a plane parallel to the lower surface of the second joining member2with respect to the butting-direction N of the second joining member2. To this inclination angle changing apparatus65b, the second forward supporting roller31bis connected. Therefore, by operating this inclination angle changing apparatus65b, the inclination angle γ2can be changed.

In this friction agitation joining apparatus80, the first forward pressing roller11is arranged as shown inFIG. 13by operating the inclination angle changing apparatus60aas follows. That is, the first forward pressing roller11is arranged in a state that one end thereof at the butted portion side3of the first joining member1is positioned at a joining-direction forward position with respect to the other end thereof and that the axis P1of this roller11is inclined relative to the butting-direction N of the first joining member1within a plane parallel to the upper surface of the first joining member1. By arranging this first forward pressing roller11as mentioned above, force in the butting direction N of the first joining member1is given to the first joining member1in accordance with the movement of the first joining member1. Furthermore, in this friction agitation joining apparatus80, the second forward pressing roller12is arranged by operating the inclination angle changing apparatus60bas follows. That is, the second forward pressing roller12is arranged in a state that one end thereof at the butted portion side3of the second joining member2is positioned at a joining-direction forward position with respect to the other end thereof and that the axis P2of this roller12is inclined relative to the butting-direction N of the second joining member2within a plane parallel to the upper surface of the second joining member2. By arranging this second forward pressing roller12as mentioned above, force in the butting direction N of the second joining member2is given to the second joining member2in accordance with the movement of the second joining member2. Accordingly, in accordance with the movement of the joining members1and2, both the joining members1and2come into strong contact with each other at the butted portion3, and moves in the predetermined direction MD in the contact state.

In this friction agitation joining apparatus80, the first forward supporting roller31ais arranged as shown inFIG. 13by operating the inclination angle changing apparatus65aas follows. That is, the first forward supporting roller31ais arranged in a state that one end thereof at the butted portion side3of the first joining member1is positioned at a joining-direction forward position with respect to the other end thereof and that the axis S1of this roller31is inclined relative to the butting-direction N of the first joining member1within a plane parallel to the lower surface of the first joining member1. Similarly, the second forward supporting roller31bis arranged by operating the inclination angle changing apparatus65bas follows. That is, the second forward supporting roller31bis arranged in a state that one end thereof at the butted portion side3of the second joining member2is positioned at a joining-direction forward position with respect to the other end thereof and that the axis S2of this roller31binclined relative to the butting-direction N of the second joining member2within a plane parallel to the lower surface of the second joining member2. By arranging the first and second forward supporting rollers31aand31bas mentioned above, both the joining members1and2come into strong contact with each other at the butted portion3.

In this friction agitation joining apparatus80, the first forward pressing roller11is arranged as shown inFIG. 15by operating the inclination angle changing apparatus60aas follows. That is, the first forward pressing roller11is arranged in a state that one end thereof at the butted portion side3of the first joining member1is positioned upper than the other end thereof and that the axis P1of this roller11is inclined relative to the butting-direction N of the first joining member1within a plane perpendicular to the joining direction WD. In this state, the first forward pressing roller11presses the first joining member1. Similarly, the second forward pressing roller12is arranged by operating the inclination angle changing apparatus60bas follows. That is, the second forward pressing roller12is arranged in a state that one end thereof at the butted portion side3of the second joining member2is positioned upper than the other end thereof and that the axis P2of this roller12is inclined relative to the butting-direction N of the second joining member2within a plane perpendicular to the joining direction WD. In this state, the second forward pressing roller12presses the second joining member2.

As shown inFIG. 16, in this friction agitation joining apparatus, the backward supporting roller32is divided into the first backward supporting roller32aand the second backward supporting roller32b. The outer diameter of the first backward supporting roller32aand that of the second backward supporting roller32bhave the same dimension. The joining-direction backward side of the first joining member1with respect to the probe inserted position is supported by the first backward supporting roller32afrom the lower surface side thereof, while the joining-direction backward side of the second joining member2with respect to the probe inserted position is supported by the second backward supporting roller32bfrom the lower surface side thereof.

In this second embodiment, the joining operation is performed as follows. The butted portion3is joined with the probe42by moving both the joining members1and2in the predetermined direction MD while measuring the surface temperature of the joined butted portion3′ of the joining members1and2.

In cases where the surface temperature of the joined butted portion3′ is higher than or lower than the predetermined temperature, poor junction such as joining defect and thermal distortion generate easily. Therefore, if it is discriminated that the surface temperature of the joined butted portion3′ is higher than or lower than the predetermined temperature during the joining, at least one of the inclination angle changing apparatuses60aand60bis operated via the controller61aand61bbased on the measured value obtained the thermometry apparatus50in order to change at least one of the inclination angles β1or β2. Thereby, the press force from the roller to be received by the joining members1and2changes in the butting direction N. As a result, generation of poor junction can be prevented assuredly. This changing operation of the inclination angle β1and β2is performed automatically. Thus, in this second embodiment, joining can be performed while preventing generation of poor junction, and therefore poor joining prevention work can be performed efficiently.

Furthermore, in this second embodiment, since the butted portion3is joined with both joining members1and2firmly adhered, a firmly joined butted portion3′ can be obtained. Also, the fault that the butted portion3detaches during the movement of the joining members1and2can be prevented.

Furthermore, since the forward pressing roller10is divided into the first forward pressing roller11and the second forward pressing roller12, each joining member1and2can be pressed firmly even if the thickness of each joining member1and2fluctuates in the longitudinal direction.

Furthermore, since the backward supporting roller32is divided into the first backward supporting roller32aand the second backward supporting roller32b, the design freedom degree of the backward supporting roller32can be increased. Accordingly, the meandering movement of the joining members1and2can be prevented by changing the mutual position of the first backward supporting roller32aand the second backward supporting roller32bor changing the circumferential speed thereof. Furthermore, straightening effect to the configuration defect of each joining member1and2can be increased.

In this second embodiment, as a characteristic regarding the joining state of the joined butted portion3′, the surface temperature of the butted portion3′ is exemplified. However, in the present invention, the characteristic regarding the joining state may be, for example, the surface residual stress of the butted portion3′.

However, the present invention is not limited to those represented by the aforementioned first and second embodiments, and allow various settings.

For example, the backward pressing roller20may be divided into a first backward pressing roller21, a second backward pressing roller22and a third backward pressing roller23.

Furthermore, the forward pressing roller10and/or the backward pressing roller20may be constituted such that they function as a driving roller for moving the joining members1and2in the predetermined direction MD or they are provided with circumferential-speed controlling mechanism.

Furthermore, in the friction agitation joining method according to the present invention, the butted portion3may be joined by moving the rotating probe42inserted into the butted portion3of the joining members1and2along the butted portion3in a state in which the position of the joining members1and2is fixed. In this case, the moving direction of the probe coincides with the joining direction.

Third Embodiment

FIGS. 17 to 21are drawings for explaining a friction agitation joining method, a method for manufacturing of butted joining members and a friction agitation joining method according to the third embodiment of the present invention. In these figures, the same reference numeral is allotted to the same component as in the aforementioned first embodiment. Hereinafter, this third embodiment will be explained by focusing on the differences between the first embodiment and the third embodiment.

In this third embodiment, the friction agitation joining apparatus80is equipped with a heating roller91as a heating device. This heating roller91is constituted by a backing roller33having the following structure. The structure of the backing roller33will be explained as follows. As shown inFIG. 18, at the peripheral surface portion of the longitudinal intermediate portion of the backing roller33, an electric heater91aas heating source is embedded along the entire circumference thereof. As shown inFIG. 17, the electric power supplying cord91bfor supplying electric power to the electric heater91ais connected to the electric heater91a. This backing roller33is made of heat-resisting materials that can withstand heat generated by the electric heater91a. By supplying electric power to this electric heater91ato generate heat, the periphery of the backing roller33is heated.

In this third embodiment, the forward pressing roller10is divided into the first forward pressing roller11and the second forward pressing roller12in the same manner as in the second embodiment, as shown inFIG. 17. That is, the first forward pressing roller11and the second forward pressing roller12are members separated each other. The outer diameter of the first forward pressing roller11and that of the second forward pressing roller12are set to have the same dimension.

Furthermore, as shown inFIG. 17, the backward pressing roller20is not equipped with a third backward pressing roller, and divided into the first backward pressing roller21and the second backward pressing roller22. That is, the first backward pressing roller21and the backward pressing roller22are members separated from each other. The outer diameter of the first backward pressing roller21and that of the second backward pressing roller22are set to have the same dimension.

In this third embodiment, the joining operation is performed as follows. That is, in advance, the periphery of backing roller33is heated by the electric heater91a. Then, during the joining, the lower surface of the joining members1and2is heated by bringing the heated periphery of the backing roller33into contact with the lower surface of the butted portion3of the joining members1and2at the probe inserted position. As a result, the heat of the periphery of the backing roller33is conducted to the lower surface of joining members1and2, and then the conducted heat is conducted from the lower surface in the thickness direction. Thereby, the portion near the lower surface in the thickness direction of the joining members1and2becomes high temperature state. InFIGS. 18 and 20, “Y” denotes a portion of the joining members1and2in a high temperature state. In the present invention, it is preferable to heat the lower surface so that the temperature of the lower surface of the joining members1and2falls within the range of from 400° to 500° because of the following reasons. If the temperature of the lower surface is less than 400° C., there is a possibility that the mixing of materials cannot be performed well due to insufficient heating. On the other hand, if it exceeds 500° C., there is a possibility that the joining members1and2may be melt due to overheating.

In a state in which the heated periphery of the backing roller33contacts the lower surface of the joining members1and2, both joining members1and2are moved in a predetermined direction MD. As a result, in accordance with the movement of the joining member1and2, the butted portion3is joined by the probe42at the probe inserted position.

In this third embodiment, since the lower surface of the probe inserted position of the butted portion3of the joining members1and2is contacted by the heated backing roller33and therefore heated, the portion near the lower surface in the thickness direction of the joining members1and2is in a high temperature state. Accordingly, the materials between the tip of the probe42and the lower surfaces of the joining members1and2can be softened very quickly, resulting in sufficient mixing of the materials. Accordingly, the generating of the root remaining portion R (seeFIG. 31) can be prevented, and as shown inFIG. 21, the butted portion3can be joined along the entire thickness length. Accordingly, according to this friction agitation joining method, even if the thickness dimension of the joining member1and2fluctuates in the longitudinal direction, the generation of the root remaining portion can be prevented assuredly, resulting in improved joining strength.

Furthermore, in this friction agitation joining method, since the joining is performed while heating the lower surface of the probe inserted position of the butted portion3of the joining members1and2by the periphery of the backing roller33, the joining operation can be performed well and the heating can be performed efficiently.

In the present invention, the joining may be performed while heating the lower surface of the joining-direction forward side of the probe inserted position of the joining members1and2by bringing the heated periphery of the heating roller91into contact with the lower surface.

Fourth Embodiment

FIGS. 22 and 23are drawings for explaining a friction agitation joining method, a method for manufacturing of butted joining members and a friction agitation joining method according to the fourth embodiment of the present invention. In these figures, the same reference numeral is allotted to the same component as in the aforementioned first embodiment. Hereinafter, this fourth embodiment will be explained by focusing on the differences between the third embodiment and the fourth embodiment.

In this fourth embodiment, the friction agitation joining apparatus80is equipped with a laser irradiation heating apparatus92as a heating apparatus. As shown inFIG. 22, this laser irradiation heating apparatus92is disposed at the lower surface side of the portion near the probe inserted position of the joining-direction forward side of the joining members1and2. On the other hand, the backing roller33has no built-in electric heater.

This laser irradiation heating apparatus92is equipped with a nozzle92bfor injecting a laser92a. This nozzle92bis disposed with the injection tip facing up.

In this fourth embodiment, a laser92ais injected from the injection tip of the nozzle92bat the time of joining, and this laser92airradiates the lower surface of the butted portion3of the joining members1and2at the joining-direction forward side of the probe inserted position to heat the lower surface. Then, the heat conducts in the thickness direction from the lower surface. Thereby, the portion near the lower surface of joining members1and2will become high in temperature (“Y” denotes the portion).

While irradiating the laser92aat the lower surface of joining members1and2, the joining members1and2are moved in the predetermined direction MD. In accordance with the movement of the joining members1and2, the butted portion3is joined by the probe42at the probe inserted position.

In this fourth embodiment, when the high temperature portion Y of the joining members1and2reaches the probe inserted position in accordance with the movement of the joining members1and2, the materials between the tip of the probe42and the lower surfaces of the joining members1and2softens very quickly, resulting in sufficient mixture of the materials. Accordingly, the generation of the root remaining portion R (seeFIG. 31) can be prevented.

In the present invention, in cases where there are no obstruction such as a backing roller33at the lower surface side of the butted portion3of the joining members1and2at the probe inserted position, the joining may be performed while heating the lower surface of the probe inserted position of the joining members1and2at the butted portion3by irradiating the laser92a.

Fifth Embodiment

FIGS. 24 and 25are drawings for explaining a friction agitation joining method, a method for manufacturing of butted joining members and a friction agitation joining method according to the fifth embodiment of the present invention. In these figures, the same reference numeral is allotted to the same component as in the aforementioned first embodiment. Hereinafter, this fifth embodiment will be explained by focusing on the differences between the third embodiment and the fifth embodiment.

In the fifth embodiment, the friction agitation joining apparatus80is equipped with a high frequency induction heating apparatus93as a heating apparatus. This high frequency induction heating apparatus93is disposed at the lower surface side of the portion near the probe inserted position of the joining-direction forward side of the joining members1and2. On the other hand, the backing roller33has no built-in electric heater.

This high frequency induction heating apparatus93is equipped with an induction coil93a. To this induction coil93a, a high frequency power source (not shown) is connected. As shown inFIG. 25, this induction coil93ais disposed at the lower surface of the joining members1and2in contact with the lower surface or near the lower surface so as to bridge the butted portion3.

In this fifth embodiment, a high frequency current is made to pass through the induction coil93aat the time of joining to thereby generate an induced current at the lower surface of the joining members1and2. Thereby, the lower surface is heated.

While generating an induced current at the lower surface of joining members1and2, the joining members1and2are moved in the predetermined direction MD. In accordance with the movement of the joining members1and2, the butted portion3is joined by the probe42at the probe inserted position.

In this fifth embodiment, when the high temperature portion Y of the joining members1and2reaches the probe inserted position in accordance with the movement of the joining members1and2, the materials between the tip of the probe42and the lower surfaces of the joining members1and2softens very quickly, resulting in sufficient mixture of the materials. Accordingly, the generation of the root remaining portion R (seeFIG. 31) can be prevented.

In the present invention, in cases where there are no obstruction such as a backing roller33at the lower surface side of the butted portion3of the joining members1and2at the probe inserted position, the joining may be performed while heating the lower surface of the probe inserted position of the joining members1and2at the butted portion3by disposing an induction coil93aat the lower surface at the probe inserted position to thereby generate an induced current in the lower surface.

Sixth Embodiment

FIGS. 26 to 28are drawings for explaining a friction agitation joining method, a method for manufacturing of butted joining members and a friction agitation joining method according to the sixth embodiment of the present invention. In these figures, the same reference numeral is allotted to the same component as in the aforementioned first embodiment. Hereinafter, this sixth embodiment will be explained by focusing on the differences between the third embodiment and the sixth embodiment.

In the sixth embodiment, the thickness t1of the first joining member1is 3 mm or less, concretely, t1is 1 mm, where the relation between the thickness t1of the first joining member1and the thickness t2of the second joining member2is given by the inequality: t2>t1(seeFIG. 28).

The friction agitation joining apparatus80is equipped with a friction agitation joining sub-joining tool45for joining the root remaining portion R (seeFIG. 31). Hereinafter, the aforementioned joining tool40for joining the butted portion3of the joining members1and2from the upper surface side, the rotor41and the probe42will be referred to as a “main joining tool”, a “main rotor” and a “main probe,” respectively, for an explanation purpose.

The sub-joining tool45is provided with a column-shaped sub-rotor46having a larger diameter and a pin-shaped sub-probe47having a smaller diameter. The sub-probe47is integrally projected from the rotational center of the end face46aof the sub-rotor46along the rotation-axis S.

The length of the sub-probe47is set to be much shorter than that of the main probe42of the main joining tool40. It is especially preferable that the length falls within the range of from 0.1 mm to 0.5 mm. The other structure of this sub-joining tool45is the same as the aforementioned main joining tool40.

This sub-joining tool45is disposed at the portion near the joining-direction forward side of the main probe inserted position of the lower surface side of the joining members1and2with the sub-probe47facing up. In this sixth embodiment, the rotating sub-probe47of the sub-joining tool45is inserted into the portion at the joining-direction forward side near the main probe inserted position from the lower surface side. Preferably, the end face46of the sub-rotor46is pressed against the lower surface of the joining members1and2. Then, in this state, both joining members1and2are moved in a predetermined direction MD so that the main probe42and the sub-probe47advance the butted portion3.

At this time, it is preferable that the insertion depth δ of the sub-probe47into the butted portion3from the lower surface (seeFIG. 28) falls within the range of from 0.1 to 0.5 mm because of the following reasons. If the insertion depth δ of the sub-probe47is less than 0.1 mm, there is a possibility that an insertion depth may be insufficient and therefore the root remaining portion may remain. On the other hand, if the insertion depth δ of the sub-probe47exceeds 0.5 mm, the force to be required for moving the joining members1and2becomes large, which in turn becomes difficult to perform the moving operation of the joining members1and2. Accordingly, it is preferable that the insertion depth δ of the sub-probe47falls within the range of from 0.1 to 0.5 mm.

In accordance with the movement of the joining members1and2, the portion near the joining-direction forward side of the probe inserted position at the butted portion3of the joining members1and2is joined shallowly by the sub-joining tool47of the sub-probe45. When, the joined portion reaches the main probe inserted position of the main joining tool40, the butted portion3is joined in the entire thickness direction by the main probe42. Accordingly, the generation of the root remaining portion R (seeFIG. 31) can be prevented.

In the present invention, as shown by the hypothetical line inFIG. 27, the joining may be performed in a state in which the rotating sub-probe47of the sub-joining tool45may be inserted into the joined butted portion3′ of the joining members1and2from the lower surface side. In cases where there are no obstruction such as a backing roller33at the lower surface side of the butted portion3of the joining members1and2at the main probe inserted position, the joining may be performed while inserting a rotating sub-probe47of the sub-joining tool45into the lower surface of the main probed inserted position of the joining members1and3at the butted portion3.

Furthermore, in the friction agitation joining method according to the present invention, the butted portion3may be joined by moving the rotating probe42inserted into the butted portion3of the joining members1and2along the butted portion3in a state in which the position of the joining members1and2is fixed. In this case, the moving direction of the probe coincides with the joining direction.

Next, concrete examples of the friction agitation joining method according to the third to sixth embodiments will be shown.

Long plate-shaped first joining members made of aluminum alloy (Materials: JIS A6063-T5, Thickness: 1 mm) and long plate-shaped second t joining members made of aluminum alloy (Materials: JIS A6063- T5, Thickness: 2 mm) were prepared. Then, side edges of the joining members1and2were butted against each other with the lower surfaces being flush with each other, and the butted portion3thereof was joined along the entire length by the aforementioned joining method according to the third embodiment.

The butted portion3of the joining members1and2was joined along the entire length by the aforementioned joining method according to the fourth embodiment. Other joining conditions are the same as those of the aforementioned fifth example.

The butted portion3of the joining members1and2was joined along the entire length by the aforementioned joining method according to the fifth embodiment. Other joining conditions are the same as those of the aforementioned fifth example.

The butted portion3of the joining members1and2was joined along the entire length by the aforementioned joining method according to the sixth embodiment. In this joining, the insertion depth δ of the sub-probe47of the sub-joining tool45was set as 0.1 mm. Other joining conditions are the same as those of the aforementioned fifth example.

About the butted joining members obtained in the above examples 5 to 8, each cross-section was observed by using a microscope, and the joining state was evaluated. As a result, no root remaining portion can be found in any butted joining member. This result shows that the joined butted joining members have high bonding strength and outstanding strength reliability.

Effects of the present invention will be summarized as follows.

According to friction-agitation-joining method of the first aspect of the present invention, by pressing joining-direction forward sides of the first joining member and the second joining member with respect to a probe inserted position from the upper surface sides by a first forward pressing roller and a second forward pressing roller, respectively, it is possible to prevent a fault such as an unexpected movement of each joining member during the joining and also to correct the configuration defect of each joining member such as torsion or curvature. Furthermore, performing the joining process in this state can prevent the generation of poor Junction such as joint defect or thermal distortion, resulting in high quality joined butted joining members.

According to the friction agitation joining method of the second aspect of the present invention, the same effects as in the first aspect of the present invention can be obtained.

According to the friction agitation joining method of the third aspect of the present invention, generation of poor junction can be prevented or suppressed, and therefore butted joining members with high quality can be obtained.

According to the friction agitation joining method of the fourth aspect of the present invention, since the butted portion is joined while heating the lower surface of the butted portion of the joining members at the probe inserted position or the joining-direction forward side, generating of the root remaining portion can be prevented, and therefore joined butted joining members with high joining strength can be obtained.

According to the friction agitation joining method of the fifth aspect of the present invention, since the butted portion is joined by moving the joining members with respect to the main probe and the sub-probe so that the probes advance along the butted portion in a state in which a rotating sub-probe of the sub-joining tool is inserted into the butted portion of the joining members or the joined butted portion, generation of root remaining portion can be prevented, and therefore butted joining members having high joining strength can be obtained.

According to the method for manufacturing butted joining members of the sixth aspect of the present invention, the same effects as in the first aspect of the present invention can be obtained.

According to the method for manufacturing butted joining members of the seventh aspect of the present invention, the same effects as in the second aspect of the present invention can be obtained.

According to the method for manufacturing butted joining members of the eighth aspect of the present invention, the same effects as in the third aspect of the present invention can be obtained.

According to the method for manufacturing butted joining members of the ninth aspect of the present invention, the same effects as in the fourth aspect of the present invention can be obtained.

According to the method for manufacturing butted joining members of the tenth aspect of the present invention, the same effects as in the fifth aspect of the present invention can be obtained.

According to the friction agitation joining apparatus of the eleventh aspect of the present invention, the friction agitation joining method of the first aspect of the present invention or the method for manufacturing butted joining members of the sixth aspect of the present invention can be performed efficiently.

According to the friction agitation joining apparatus of the twelfth aspect of the present invention, the friction agitation joining method of the second aspect of the present invention or the method for manufacturing butted joining members of the seventh aspect of the present invention can be performed efficiently.

According to the friction agitation joining apparatus of the thirteenth aspect of the present invention, the friction agitation joining method of the third aspect of the present invention or the method for manufacturing butted joining members of the eighth aspect of the present invention can be performed efficiently.

According to the friction agitation joining apparatus of the fourteenth aspect of the present invention, the friction agitation joining method of the fourth aspect of the present invention or the method for manufacturing butted joining members of the ninth aspect of the present invention can be performed efficiently.

According to the friction agitation joining apparatus of the fifteenth aspect of the present invention, the friction agitation joining method of the fifth aspect of the present invention or the method for manufacturing butted joining members of the tenth aspect of the present invention can be performed efficiently.

The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intent, in the use of such terms and expressions, of excluding any of the equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

INDUSTRIAL APPLICABILITY

A friction agitation joining method, a method for manufacturing joined butted members and a friction agitation joining apparatus are preferably used for manufacturing metal plate-shaped members used as, for example, flooring materials, wall materials and ceiling materials for transporting device such as automobiles, aircrafts and railroad vehicles.