Method for manufacturing heat exchanger plate and method for friction stir welding

The method for manufacturing a heat exchanger plate includes a lid groove closing process to insert a lid plate into a lid groove formed at a periphery of a concave groove opening to a surface of a base member; and a primary joining process to perform friction stirring while relatively moving a primary joining rotary tool equipped with a stirring pin along a butting portion of a side wall of the lid groove and a side surface of the lid plate, and in the primary joining process, the rotating stirring pin is inserted into the butting portion, and the friction stirring is performed in a state of only the stirring pin being in contact with the base member and the lid plate.

TECHNICAL FIELD

The present invention relates to a method for manufacturing a heat exchanger plate and a method for friction stir welding.

BACKGROUND ART

In a patent document 1, there describes a method for manufacturing a heat exchanger plate to exchange heat or the like while fluid is flowing through a channel formed in a base member. A lid groove opening to a surface of the base member and a concave groove formed on a bottom surface of the lid groove are formed in the base member. When a heat exchanger plate is manufactured, a lid plate is disposed in the lid groove, and a friction stir welding is performed to a butting portion of a side surface of the lid plate and a side wall of the lid groove. When the friction stir welding is performed, a stirring pin of a rotary tool is inserted into a deep position of the butting portion while a bottom surface of a shoulder of the rotary tool is in contact with the base member and the lid plate. Air-tightness and water-tightness of the heat exchanger plate can be improved by performing the friction stirring to the deep position of the butting portion.

PRIOR ART DOCUMENT

Patent Document

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

For example, when the channel of the heat exchanger plate is formed at a deep position in the base member, it is needed to make a depth of the lid groove large and to make a thickness of the lid plate large. In such a case, a length and an outer diameter of the stirring pin of the rotary tool to be used for friction stir welding need to be large. Further, an outer diameter of the shoulder also needs to be larger as the stirring pin is enlarged. However, a friction between the shoulder and the base member and the lid plate becomes larger as the outer diameter of the shoulder becomes larger. Therefore, there is a problem that a load applied on a friction stir device becomes large. For this reason, it has been hard to form a channel at a deep position in the heat exchanger plate.

As another case, for example, there is a case in which a rotary tool is inserted vertically to an overlapped portion formed by overlapping two plate-like metal members, from a surface of the metal members to perform friction stir welding for the metal members. Even in such a case, when a thickness of a metal member is large, so that the overlapped portion is located at a deep position, there is a problem that it is hard to perform friction stir welding.

In such a viewpoint, it is an object of the present invention to provide a method for manufacturing a heat exchanger plate capable of easily performing friction stir welding for a deep position of the heat exchanger plate and improving air-tightness and water-tightness. And it is also an object of the present invention to provide a method for friction stir welding capable of easily performing friction stir welding even when an overlapped portion of overlapped metal members is located at a deep position.

Means for Solving the Problem

In order to solve the problem, a method of the present invention includes a lid groove closing process to insert a lid plate into a lid groove formed at a periphery of a concave groove opening to a surface of a base member; and a primary joining process to perform friction stirring while relatively moving a rotary tool equipped with a stirring pin along a butting portion of a side wall of the lid groove and a side surface of the lid plate, and in the primary joining process, the stirring pin which is rotating is inserted into the butting portion, and the friction stirring is performed in a state of only the stirring pin being in contact with the base member and the lid plate.

Further, a method of the present invention includes a heating medium pipe insertion process to insert a heating medium pipe into a concave groove formed on a bottom surface of a lid groove opening to a surface of a base member; a lid plate insertion process to insert a lid plate into the lid groove; and a primary joining process to perform friction stirring while relatively moving a rotary tool along a butting portion of a side wall of the lid groove and a side surface of the lid plate, and in the primary joining process, the stirring pin which is rotating is inserted into the butting portion, and the friction stirring is performed in a state of only the stirring pin being in contact with the base member and the lid plate.

According to these methods, only the stirring pin of the rotary tool is in contact with the base member and the lid plate, so friction of the rotary tool with the lid plate and the base member to be joined together with each other can be reduced in comparison with the prior manufacturing method. Therefore, a load applied on the friction stir device can be reduced. That is, according to the present invention, friction stir welding can be easily performed at a deep position of the butting portion because a load applied on the friction stir device can be reduced. Thereby, a channel can be easily formed at a deep position in the heat exchanger plate. Further, as friction stirring can be performed at a deep position of the butting portion, air-tightness and water-tightness of the heat exchanger plate can be improved.

Further, it is preferable that a preliminary joining process to preliminarily join the butting portion is further included before the primary joining process. According to this manufacturing method, an aperture of the butting portion can be prevented from being generated when the primary joining process is performed.

Further, a method of the present invention includes a closing process to overlay a lid plate on a front surface of a base member to cover a concave portion or a concave groove opening to the front surface of the base member; and a primary joining process to insert a rotary tool equipped with a stirring pin from a front surface of the lid plate, and to move the rotary tool along an overlapped portion of the front surface of the base member and a back surface of the lid plate, and in the primary joining process, friction stirring is performed to the overlapped portion in a state of only the stirring pin being in contact with both of the base member and the lid plate or with only the lid plate.

Further, a method of the present invention includes a closing process to overlay a lid plate on a front surface of a base member to cover a concave portion or a concave groove opening to the front surface of the base member; and a primary joining process to insert a rotary tool equipped with a stirring pin from a back surface of the base member, and to move the rotary tool along an overlapped portion of the front surface of the base member and a back surface of the lid plate, and in the primary joining process, friction stirring is performed to the overlapped portion in a state of only the stirring pin being in contact with both of the base member and the lid plate or with only the base member.

According to these methods, only the stirring pin of the rotary tool is in contact with the base member or the lid plate, or with both of the base member and the lid plate, so friction between the rotary tool and one of the base member and the lid plate or, friction between the rotary tool and both of them can be reduced in comparison with the prior manufacturing method. Therefore, a load applied on the friction stir device can be reduced. That is, according to the present invention, friction stir welding can be easily performed to the overlapped portion located at a deep position because a load applied on the friction stir device can be reduced. Thereby, a channel can be easily formed also at a deep position in the heat exchanger plate.

Further, it is preferable that a preliminary joining process to preliminarily join the overlapped portion is further included before the primary joining process. According to this manufacturing method, an aperture of the overlapped portion can be prevented from being generated when the primary joining process is performed.

Further, it is preferable that a deburring process to remove burrs, which is generated by friction stirring using the rotary tool, is further included after finishing the primary joining process. According to this manufacturing method, the base member or the lid plate can be finely finished.

Further, a method for friction stir welding of the present invention to join two metal members with use of a rotary tool equipped with a stirring pin, includes an overlapped portion forming process to overlap a front surface of one metal member and a back surface of the other metal member to form an overlapped portion; and a primary joining process to insert the stirring pin, which is rotating, from a front surface of the other metal member, and to perform friction stirring to the overlapped portion in a state of only the stirring pin being in contact with both of the one metal member and the other metal member or with only the other metal member.

According to this method, only the stirring pin of the rotary tool is in contact with both or one of the metal members, so friction between the rotary tool and one of the one metal member and the other metal member, or friction between the rotary tool and both of them can be reduced in comparison with the prior manufacturing method. Therefore, a load applied on the friction stir device can be reduced. That is, according to the present invention, friction stir welding can be easily performed to the overlapped portion located at a deep position because a load applied on the friction stir device can be reduced.

Further, it is preferable that a preliminary joining process to preliminarily join the overlapped portion is further included before the primary joining process. According to this method, an aperture of the overlapped portion can be prevented from being generated when the primary joining process is performed.

Further, it is preferable that a deburring process to remove burrs, which is generated by friction stirring using the rotary tool, is further included after finishing the primary joining process. According to this method, the joined metal members can be finely finished.

Effect of the Invention

By a method for manufacturing a heat exchanger plate according to the present invention, friction stir welding can be easily performed to a butting portion located at a deep position, and air-tightness and water-tightness can be improved. Further, by a method for friction stir welding according to the present invention, friction stir welding can be easily performed even in a case where an overlapped portion of overlapped metal members is located at a deep position.

MODE FOR CARRYING OUT THE INVENTION

First Embodiment

A first embodiment of the present invention will be described in detail with reference to the attached drawings. First, a primary joining rotary tool and a preliminary joining rotary tool which are used in this embodiment will be described.

As shown inFIG. 1A, the primary joining rotary tool F has a coupling part F1and a stirring pin F2. The primary joining rotary tool F corresponds to a rotary tool in the scope of claim for patent. The primary joining rotary tool F is made of, for example, tool steel. The coupling part F1is a part to be coupled to a rotary shaft D of a friction stir device shown inFIG. 1B. The coupling part F1has a cylindrical shape, and has screw holes B, B for fastening bolts.

The stirring pin F2hangs down from the coupling part F1, and is coaxial with the coupling part F1. The stirring pin F2has a tapered shape so as to have a smaller diameter as it goes away from the coupling part F1. The stirring pin F2has a spiral groove F3formed on the outer peripheral surface thereof. In this embodiment, the spiral groove F3is formed so as to rotate in a counter-clockwise direction as it goes downward because the primary joining rotary tool F is rotated in the clockwise direction.

Note that, in a case where the primary joining rotary tool F is rotated in the counter-clockwise direction, it is preferable that the spiral groove F3is formed so as to rotate in the clockwise direction as it goes downward. By forming the spiral groove F3in such a manner, plastically fluidized metal is led to a front end side through the spiral groove F3when friction stirring is performed. Thereby, an amount of metal to be leaked to the outside of metal members (a base member2and a lid plate5to be described later) to be joined, can be reduced.

As shown inFIG. 1B, when friction stir welding is performed by use of the primary joining rotary tool F, only the rotating stirring pin F2is inserted into the metal members to be joined, and is moved in a state where the coupling part F1is kept to be apart from the metal members to be joined. In other words, the friction stir welding is performed while a base part of the stirring pin F2is exposed. A plasticized region W is formed along a moving locus of the primary joining rotary tool F by hardening of metal to which friction stirring is performed.

As shown inFIG. 2A, the preliminary joining rotary tool G has a shoulder part G1and a stirring pin G2. For example, the preliminary joining rotary tool G is made of tool steel. The shoulder part G1is a part to be coupled to the rotary shaft D of the friction stir device, and also a part to hold plastically fluidized metal, as shown inFIG. 2B. The shoulder part G1has a cylindrical shape. A lower end face of the shoulder part G1is formed as a recessed portion in order to prevent the fluidized metal from flowing out to the outside.

The stirring pin G2hangs down from the shoulder part G1, and is coaxial with the shoulder part G1. The stirring pin G2has a tapered shape so as to have a smaller diameter as it goes away from the shoulder part G1. The stirring pin G2has a spiral groove G3formed on the outer peripheral surface thereof.

When friction stir welding is performed with use of the preliminary joining rotary tool G, the rotating stirring pin G2and a lower end portion of the shoulder part G1are inserted into metal members to be joined and is moved as shown inFIG. 2B. A plasticized region W1is formed along a moving locus of the preliminary joining rotary tool G by hardening of metal for which friction stirring is performed.

Next, a heat exchanger plate of this embodiment will be described. The heat exchanger plate1according to this embodiment is constituted mainly by a base member2and a lid plate5as shown inFIG. 3. The base member2has an approximately rectangular parallelepiped shape. A concave groove3and a lid groove4are formed in the base member2. Material of the base member2is not specially limited as far as friction stirring can be performed. The material is an aluminum alloy in this embodiment.

The concave groove3is formed in the middle of the base member2so as to pass through from one side surface to the other side surface. The concave groove3is formed on a bottom surface of the lid groove4so as to be recessed. A bottom part of the concave groove3has an arc shape. The concave groove3is open on a front surface2aside of the base member2.

The lid groove4has a larger width than the concave groove3, and is formed continuously with the concave groove3on the front surface2aside of the concave groove3. The lid groove4has a rectangle shape in a sectional view, and is open on the front surface2aside thereof.

The lid plate5is a plate-like member to be inserted into the lid groove4. In this embodiment, the lid plate5is made of an aluminum alloy equivalent to the material of the base member2. The lid plate5has the same shape as a hollow part of the lid groove4in order to be inserted into the lid groove4without a gap.

A pair of side walls of the lid groove4and a pair of side surfaces of the lid plate5are abutted respectively, so that butting portions J, J are formed. Each of the butting portions J, J is joined over a whole length in a depth direction thereof by friction stirring. A space enclosed with the concave groove3of the heat exchanger plate1and a bottom surface of the lid plate5is a channel through which a fluid flows.

Next, a method for manufacturing a heat exchanger plate according to the first embodiment will be described. In the method for manufacturing a heat exchanger plate, a preparing process, a lid groove closing process, a tab member disposing process, a preliminary joining process, and a primary joining process are performed.

As shown inFIG. 4A, the preparing process is a process to prepare the base member2. First, the base member2is fixed to a pedestal K with a clamp (not shown). And the concave groove3and the lid groove4are formed by means of cutting with use of an endmill or the like. Note that, the base member2having the concave groove3and the lid groove4formed in advance by die-casting, extrusion molding, or the like, may be used.

As shown inFIG. 4B, the lid groove closing process is a process where the lid plate5is inserted into the lid groove4. Side walls of the lid groove4and side surfaces of the lid plate5are abutted respectively, so that the butting portions J, J are formed. A front surface of the lid plate5is flush with the front surface2a.

As shown inFIG. 5, the tab member disposing process is a process where tab members10,10are disposed at side surfaces of the base member2. A tab member10is a member in which a start position or an end position for friction stirring to be described later is set. A side surface of a tab member10abuts on one of the opposing side surfaces of the base member2, and is disposed on extension lines of the butting portions J, J. In this embodiment, a tab member10is made of an aluminum alloy equivalent to the material of the base member2. A tab member10is joined by welding inner corner portions formed with the tab member10and the base member2.

As shown inFIG. 6A, the preliminary joining process is a process where friction stir welding is preliminarily performed to the butting portions J, J with use of the preliminary joining rotary tool G. A start position and an end position of the preliminary joining process are not particularly limited as far as they are located on a surface or surfaces of the base member2and the tab members10. In this embodiment, they are set on a surface of a tab member10.

Specifically, a start position of the preliminary joining process is set on a surface of one tab member10, and friction stir welding is performed over the whole length of one butting portion J. The plasticized region W1is formed along a moving locus of the preliminary joining rotary tool G. And thus, after the preliminary joining rotary tool is moved to the other tab member10, the preliminary joining rotary tool is made a turn in the surface of the other tab member10as it is. Then, friction stir welding is performed over the whole length of the other butting portion J. After the preliminary joining rotary tool G is moved to the one tab member10, the preliminary joining rotary tool G is removed from the one tab member10.

As shown inFIG. 6B, the primary joining process is a process where friction stir welding is performed for the butting portions J, J with use of the primary joining rotary tool F. It is preferable that a start position and an end position of the primary joining process are set on the surface of a tab member10. When the primary joining rotary tool F is inserted into the tab member10, a pull-out hole formed by the preliminary joining rotary tool G may be used. On the other hand, a pilot hole is formed in the tab member10in advance, and the primary joining rotary tool F may be inserted through the pilot hole.

In the primary joining process, friction stir welding is performed so as to trace the plasticized region W1formed in the preliminary joining process. In the primary joining process, it is preferable that the primary joining rotary tool F is inserted until a front end of the primary joining rotary tool F reaches a bottom surface of the lid groove4. As the stirring pin F2is made to have a length longer than a depth of the lid groove4, the coupling part F1does not abut on the base member2nor the lid plate5even when the front end of the stirring pin F2reaches the bottom surface of the lid groove4. That is, in the primary joining process, a bottom surface of the coupling part F1does not press upon the front surface of the base member2nor the front surface of the lid plate5.

The plasticized region W is formed along the moving locus of the primary joining rotary tool F. It is preferable that a distance between a butting portion J and the concave groove3is set so that plastically fluidized material does not flow in the concave groove3while the primary joining process is being performed. After finishing the primary joining process, the tab members10are removed from the base member2by cutting.

Further, after finishing the primary joining process, a deburring process where burrs generated by friction stirring are removed by cutting may be performed. By performing the deburring process, the surfaces of the base member2and the lid plate5can be finished to be smooth.

By the method for manufacturing the heat exchanger plate according to this embodiment described above, only the stirring pin F2of the primary joining rotary tool F abuts on the base member2and the lid plate5. Therefore, a friction of the primary joining rotary tool F with the lid plate5and the base plate2can be reduced in comparison with a prior method for manufacturing, so that the load to be applied on the friction stir device can be reduced. That is, according to this embodiment, the load applied to the friction stir device can be reduced even when friction stirring is performed for a deep position. Therefore, the channel of the heat exchanger plate1can be easily formed at a deep position.

Further, in the primary joining process, it is not always necessary to perform friction stirring over the whole depths of the butting portions J, J. However, by performing friction stirring over the whole depths of the butting portions J like this embodiment, air-tightness and water-tightness of the heat exchanger plate1can be improved.

Further, by performing the preliminary joining process, when the primary joining process is performed, apertures between the base member2and the lid plate5can be prevented from being generated. And in the preliminary joining process and the primary joining process, each of the preliminary joining rotary tool G and the primary joining rotary tool F is moved in a procedure of writing in one stroke in which each of the preliminary joining rotary tool G and the primary joining rotary tool F is not removed from the base member2halfway in the friction stirring. Therefore, time and labor of the work can be reduced.

Note that, in the preliminary joining process, friction stirring may be performed discontinuously so that the plasticized region W1by the preliminary joining rotary tool G is formed intermittently. Further, in the preliminary joining process, the butting portions J, J may be joined by welding. And further, a tab member10and the base member2may be preliminarily joined by the preliminary joining rotary tool G.

Second Embodiment

Next, a second embodiment of the present invention will be described. A heat exchanger plate according to the second embodiment is different from the first embodiment in the point that this heat exchanger plate is provided with a heating medium pipe6. The heating medium pipe6is a member through which a fluid flows.

In a method for manufacturing the heat exchanger plate according to the second embodiment, a preparing process, a heating medium pipe insertion process, a lid groove closing process, a preliminary joining process, and a primary joining process are performed.

As shown inFIG. 7A, the preparing process is a process to prepare the base member2.

As shown inFIG. 7B, the heating medium pipe insertion process is a process to insert the heating medium pipe6into the concave groove3. Sizes and the like of the concave groove3and the heating medium pipe6can be appropriately set. In this embodiment, an outer diameter of the heating medium pipe6is substantially the same as a width and a depth of the concave groove3.

The lid groove closing process is a process to insert the lid plate5into the lid groove4. Each butting portion J is formed by butting of a side wall of the lid groove4on a side surface of the lid plate5. When the lid plate5is inserted into the lid groove4completely, the lid plate5contacts with the heating medium pipe6, and the front surface2aof the base member2is flush with the front surface of the lid plate5.

The preliminary joining process is a process to perform joining preliminarily for the butting portions J. The preliminary joining process is performed in the same manner as the first embodiment.

As shown inFIG. 8, the primary joining process is a process to perform friction stir welding for the butting portions J, J with use of the primary joining rotary tool F. The primary joining process is performed in the same manner as the first embodiment. The plasticized regions W, W are formed along the moving locus of the primary joining rotary tool F. Each plasticized region W is formed over the whole depth of one of the butting portions J, J.

The method for manufacturing the heat exchanger plate according to the second embodiment can exhibit the effect substantially equivalent to the first embodiment. Further, the heat exchanger plate1A equipped with the heating medium pipe6can be easily manufactured.

For example, the shapes of the concave groove3, the lid groove4, the lid plate5, and the heating medium pipe6according to the first embodiment and the second embodiment are just examples, and these may be other shapes. Further, when a level difference is generated between the front surface2aof the base member2and a surface of the plasticized region W after the primary joining process, a build-up welding may be performed to eliminate the level difference. Or, a metal member is placed on the surface of the plasticized region W, and friction stir welding may be performed for this metal member and the base member2with a rotary tool.

In this embodiment, the case having the lid groove4is exemplified. However, the lid plate5may be directly inserted into the concave groove3without the lid groove4.

As shown inFIG. 8B, in a case where a gap part Q is formed around the heating medium pipe6, the gap part Q may be embedded by the primary joining process. When the lid plate5is inserted into the lid groove4in the lid groove closing process, the gap part Q is formed by the concave groove3, the bottom surface of the lid plate5, and the heating medium pipe6. In the primary joining process, plastically fluidized material made by the primary joining rotary tool F is flowed in the gap part Q. Thereby, the gap part Q around the heating medium pipe6is filled with metal, so that air-tightness and water-tightness can be further improved.

Third Embodiment

Next, a third embodiment of the present invention will be described. In a method for manufacturing the heat exchanger plate according to the third embodiment, the lid groove4is not formed in the base member2, and a lid plate5is placed on the front surface2aof the base member2. The method for manufacturing the heat exchanger plate according to the third embodiment differs from the first embodiment in this point.

In the method for manufacturing the heat exchanger plate according to the third embodiment, a preparing process, a concave groove closing process, a preliminary joining process, and a primary joining process are performed.

As shown inFIG. 9A, the preparing process is a process to prepare a base member2. A concave groove3is formed on the front surface2aof the base member2.

The concave groove closing process (closing process) is a process to place a lid plate5on the front surface2aof the base member2to cover the top of the concave groove3. In the concave groove closing process, an overlapped portion J1is formed by overlapping the front surface2aof the base member2and a back surface5bof the lid plate5.

The preliminary joining process is a process to perform joining preliminarily for the overlapped portion J1. In the preliminary joining process of this embodiment, the preliminary joining rotary tool G is inserted from side surfaces of the base member2and the lid plate5to perform friction stir welding for the overlapped portion J1. After the preliminary joining process, there remains a plasticized region W1formed on the side surfaces of the base member2and the lid plate5.

As shown inFIG. 9B, the primary joining process is a process to perform friction stir welding to the overlapped portion J1with use of the primary joining rotary tool F. In this embodiment, the front end of the stirring pin F2of the primary joining rotary tool F is inserted from a front surface5aof the lid plate5vertically into the base member2. And, in the primary joining process, friction stirring is performed without contacting the coupling part F1with the lid plate5. Thus, the heat exchanger plate1A is manufactured.

Even in a case where a method for manufacturing a heat exchanger plate has a process configuration of placing the lid plate5having a large thickness on the surface2aof the base member2without forming the lid groove4like the method for manufacturing the heat exchanger plate according to the third embodiment, a heat exchanger plate1B can be easily manufactured. That is, in the third embodiment, the thickness of the lid plate5is large, so that the overlapped portion J1is located at a deep position. However, as only the stirring pin F2is configured to contact with the base member2and the lid plate5, a friction between the primary joining rotary tool F and a group of the base member2and the lid plate5can be reduced in comparison with the prior method for manufacturing, so that the load applied on the friction stir device can be reduced. Namely, according to this embodiment, the load applied on the friction stir device can be reduced even in a case where friction stirring is performed at a deep position. Therefore, a channel of the heat exchanger plate1A can be easily formed at a deep position.

Further, by performing the preliminary joining process, when the primary joining process is performed, an aperture between the base member2and the lid plate5can be prevented from being generated.

Further, in the preliminary joining process, friction stirring may be discontinuously performed so that the plasticized region W1by the preliminary joining rotary tool G is formed intermittently. And further, in the preliminary joining process, the overlapped portion J1may be joined by welding. Further, the preliminary joining process and the primary joining process may be performed with use of a tab member like the first embodiment.

And further, in this embodiment, the stirring pin F2is set to be inserted to a position where the front end of the stirring pin F2reaches the base member2. However, it may be set so that the front end of the stirring pin F2does not reach the base member2. That is, the front end of the stirring pin F2is inserted to a position where the stirring pin F2is in contact with only the lid plate5, and in that state, friction stirring may be performed for the overlapped portion J1. In such a case, the lid plate5and the base member2are plastically fluidized because of frictional heat generated by rubbing the lid plate5with the stirring pin F2, and thereby the overlapped portion J1is joined.

Further, in this embodiment, the primary joining rotary tool F is inserted from the front surface5aof the lid plate5, but friction stirring may be performed to the overlapped portion J1by inserting the primary joining rotary tool F from a back surface2bof the base member2. Even in such a case, the stirring pin F2may be set to be inserted to a position where the stirring pin F2comes into contact with both of the base member2and the lid plate5, or also may be set to be inserted to a position where the stirring pin F2is in contact with only the base member2, to perform friction stirring.

Fourth Embodiment

Next, a fourth embodiment of the present invention will be described. A method for manufacturing a heat exchanger plate according to the fourth embodiment differs from the third embodiment in a point that a concave portion20provided with a large recess is formed.

In the method for manufacturing a heat exchanger plate according to the fourth embodiment, a preparing process, a closing process, a preliminary joining process, and a primary joining process are performed.

The preparing process is a process to prepare a base member2, as shown inFIG. 10A. The concave portion20is formed on a front surface2aof the base member2. The concave portion20is a much wider recess than the concave groove3.

The concave portion closing process (closing process) is a process to place a lid plate5on the front surface2aof the base member2to cover the top of the concave portion20. In the concave portion closing process, an overlapped portion J1is formed by overlaying a back surface5bof the lid plate5on the front surface2aof the base member2. As shown inFIG. 10B, the preliminary joining process and the primary joining process are equivalent to the third embodiment, so a detailed description will be omitted. Thus, a heat exchanger plate1C is manufactured.

The method for manufacturing the heat exchanger plate according to the fourth embodiment can exhibit the effect substantially equivalent to the third embodiment. Further, according to the fourth embodiment, the heat exchanger plate1C can be easily manufactured even in the case of placing thereon the lid plate5having a large thickness and of being provided with the concave portion20larger than the concave groove3.

Further, in this embodiment, the stirring pin F2is set to be inserted to a position where the front end of the stirring pin F2reaches the base member2. However, the stirring pin F2may be set so that the front end of the stirring pin F2does not reach the base member2, that is, the stirring pin F2may be set to be inserted to a position where the stirring pin F2is in contact with only the lid plate5, to perform friction stirring to the overlapped portion J1. In such a case, the lid plate5and the base member2are plastically fluidized because of frictional heat generated by rubbing the lid plate5with the stirring pin F2, thus the overlapped portion J1is joined.

Further, in this embodiment, the primary joining rotary tool F is inserted from the front surface5aof the lid plate5, but friction stirring may be performed for the overlapped portion J1by inserting the primary joining rotary tool F from a back surface2bof the base member2. Even in this case, the stirring pin F2may be set to be inserted to a position where the stirring pin F2comes into contact with both of the base member2and the lid plate5, or also may be set to be inserted to a position where the stirring pin F2is in contact with only the base member2, to perform friction stirring.

Fifth Embodiment

Next, a method for friction stir welding according to a fifth embodiment of the present invention will be described. The fifth embodiment differs from the other embodiments in a point that two metallic members having no channel like the concave groove3or the concave portion20are joined.

In the method for friction stir welding according to the fifth embodiment, a preparing process, an overlapping process, a preliminary joining process, and a primary joining process are performed.

As shown inFIG. 11A, the preparing process is a process to prepare metal members31,32. The metal members31,32are plate-like metal members. The sort of the metal members31,32may be appropriately selected from metals for which friction stirring can be performed.

The overlapping process is a process to overlap the metal members31,32. In the overlaying process, a back surface32bof the metal member32is overlaid on a front surface31aof the metal member31to form an overlapped portion J1.

The preliminary joining process is a process to preliminarily join for the overlapped portion J1. In the preliminary joining process, the preliminary joining rotary tool G is inserted from side surfaces of the metal members31,32in this embodiment, to perform friction stir welding for the overlapped portion J1. After the preliminary joining process, there remains a plasticized region W1formed on the side surfaces of the metal members31,32.

The primary joining process is a process to perform friction stir welding for the overlapped portion J1with use of the primary joining rotary tool F. In this embodiment, the primary joining rotary tool F is set so that the primary joining rotary tool F is inserted vertically from a front surface32aof the metal member32, and the front end of the stirring pin F2enters the metal member31. Further, in the primary joining process, friction stirring is performed without contacting of the coupling part F1with the metal member32. Thus, a composite plate1D is manufactured.

By the method for manufacturing a heat exchanger plate according to the fifth embodiment, the composite plate1D without channel in the inside can be easily manufactured. Even in a special case where the thickness of the metal member32is large and the overlapped portion J1is located at a deep position, friction between the primary joining rotary tool F and the metal members31,32can be reduced in comparison with the prior manufacturing method because only the stirring pin F2is in contact with the metal members31,32. Therefore, the load applied on the friction stir device can be reduced. Thus, even in a case where the overlapped portion J1is located at a deep position, friction stir welding can be easily performed.

Further, since the preliminary joining process is performed, an aperture between the metal members31,32can be prevented from being generated when the primary joining process is performed.

Further, in the preliminary joining process, friction stirring may be discontinuously performed so that the plasticized region W1by the preliminary joining rotary tool G is formed intermittently. And further, in the preliminary joining process, the overlapped portion J1may be joined by welding. Further, the preliminary joining process and the primary joining process may be performed with use of a tab member like the first embodiment.

Further, as shown inFIG. 11B, when the primary joining process is performed, friction stirring may be performed in a state where the front end of the stirring pin F2does not reach the metal member31, that is, the stirring pin F2is in contact with only the metal member32. In such a case, both of the metal members31,32can be joined by contacting of the plasticized region N with the overlapped portion J1. That is, the metal members31,32are plastically fluidized because of frictional heat generated by rubbing the metal member32with the stirring pin F2, thus the overlapped portion J1can be joined.

DESCRIPTION OF THE SYMBOLS