Abstract:
When an insertion force of a rotary tool  340  has searched, it is made clearly that the force at the insertion initial time is large and when a friction stir joining is an ordinary operation time, the force becomes small. According, it is preferable to make small the insertion force at the insertion initial time. To members  20, 30  to be subjected to a joining at a position where the friction stir joining starts a hole  50  is opened, and this hole  50  after the rotary tool  340  has inserted, since a move of the rotary tool  340  is made to begin, a lowering of the insertion force can be attained.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a manufacturing method of a structure body according to a friction stir joining method and, for example, the present invention is suitable for a joining of hollow extruded frame members. 
     2. Prior Art 
     A friction stir joining method is a method in which by rotating a round rod (it is called as a rotary tool) which is inserted to a joining portion and moving it along to the joining line, the joining portion is exothermic heated and is softened and solid state fludized and a solid state joining is carried out. The rotary tool comprises a small diameter portion for inserting to the inserting portion and a large diameter portion which positions at an outside. The small diameter portion and the large diameter portion of the rotary tool have the same axis. A boundary between the small diameter portion and the large diameter portion of the rotary tool is inserted slightly to the joining portion. The rotary tool is inclined toward a rear portion against an advancing direction of the joining. 
     In the friction stir joining, since the rotary tool is inserted to a metal, a large axial insertion force is necessary. In a joining of a hollow extruded frame member, supporting a plate which is orthogonal to a face plate of the hollow extruded frame member is provided integrally and then a bending of the plate according to the insertion force of the friction stir joining can be prevented. 
     The above stated technique is disclosed in Japanese application patent laid-open publication No. Hei 09-309164 (EP 0797043 A2). 
     Since friction stir joining is carried out by inserting compulsively the rotary tool to the members to be subjected to the joining, it is necessary to employ a large insertion force. For this reason, it is necessary to burden bearing members of the rotary tool to the large axial insertion force and this invites a high cost in the manufacture of the apparatus. 
     Further, when the member to be subjected to the joining is a hollow extruded frame member, the inconvenience such face plate bends by the insertion force causes. To prevent this, it is necessary to form thick a thickness of a support plate of the face plate. For this reason, a weight of the hollow extruded frame member becomes large and a weight of the structure body in which the hollow extruded frame members are joined becomes large. 
     Further, since the two members to be subjected to the joining are combined simply by a temporary fixing welding, according to the insertion of the rotary tool there is an afraid that the temporary fixing welding may be cut down. When the cut down of the temporary fixing welding an interval between the two members to be subjected to the joining changes accordingly it is impossible to carry out a suitable joining. 
     When the insertion force of the rotary tool is searched, such an insertion force is large during the insertion initial time. When the friction stir joining becomes to an ordinary condition, the insertion force becomes small. This is considered that the immediately after the joining initial time a raise in temperature of the member to be subjected to the joining is not generated. 
     SUMMARY OF THE INVENTION 
     An object of the present invention resides in a manufacturing method of a structure body that an insertion force of a rotary tool to make small. 
     When the insertion force of the rotary tool is searched, it has became clear that such a force is large during the insertion initial time and the friction stir joining becomes to an ordinary operation condition such a force becomes small. As a result, it is necessary to make low the insertion force during the insertion initial time. 
     Then a hole is provided on the member to be subjected to the joining which positions at the position where the friction stir joining starts, and after the rotary tool is inserted to this hole, the move of the rotary tool (relatively move against the member to be subjected to the joining) starts, accordingly the lowering of the insertion force can be attained. 
    
    
     BRIEF DESCRIPTION OF DRAWING 
     FIG. 1 is a longitudinal cross-section view of a joining portion of one embodiment according to the present invention; 
     FIG. 2 is a plan view of FIG. 1; 
     FIG. 3 is an explanatory view of an insertion force oil a friction stir joining; 
     FIG. 4 is a perspective view of a car body of a railway vehicle; and 
     FIG. 5 is a perspective view of a friction stir joining equipment. 
    
    
     DESCRIPTION OF THE INVENTION 
     One embodiment according to the present invention will be explained referring to from FIG. 1 to FIG.  5 . This is an example of a car vehicle as a structure body. FIG. 2 shows an end portion of a longitudinal direction of a side structure body  201 . 
     A car body is comprised of the side structure body  201 , a roof structure body  202  for constituting a roof, a stand frame  203  for constituting a floor, and an end structure body  204  for constituting an end portion of a longitudinal direction. The side structure  201 , the roof structure body  202 , the stand frame  203  are constituted respectively by joining plural extruded frame members. A longitudinal direction of the extruded frame member is a longitudinal direction of the car body. The extruded frame member is an aluminum alloy made frame member. 
     The side structure body  201  is comprised of extruded frame members  10 ,  20 ,  30 ,  40 . In the extruded frame members  20  and  30 , a window  210  is formed. An inlet and outlet port  220  of the side structure body  201  exists in the extruded frame members  10 ,  20 ,  30 ,  40 . To the inlet and outlet port  220 , after the extruded frame members  10 ,  20 ,  30 ,  40  are joined, in many cases a frame is welded. Similarly to this it is performed to the window  210 . The extruded frame members  10 ,  20 ,  30  of the inlet and outlet port  220  is cut off in a midway, respectively. 
     This side structure body  201  is comprised of the four extruded frame members, however in a case of a hollow extruded frame member, it is comprised of further many extruded frame members. Further, the window  210  can be comprised of three extruded frame members. In this case, the central extruded frame member is cut off in a midway. 
     The construction of the extruded frame member of the side structure body  201  will be explained. Herein, the extruded frame members  20 ,  30  will be explained. Other frame members  10 ,  40  will be explained similarly. The extruded frame members  20 ,  30  are the hollow extruded frame members. The hollow extruded frame members  20 ,  30  are comprised of two face plates  21 ,  22  and  31 ,  32 , plural ribs  23  and  33  which connected to the both and are arranged in a truss shape, and support plates  24 ,  34  for connecting two face plates in an end portion (a joining portion) of a width direction of the hollow extruded frame members. 
     To the end portions (the joining portion) of the width directions of the face plates  21 ,  22  and  31 ,  32 , there are raised portions  25  and  35  which are projected toward the outer sides. To the end portion of the width direction of the hollow extruded frame member  30  there are projection chips  36 ,  36  which are projected toward directing for other hollow extruded frame member  20 . The projection chips  36 ,  36  are inserted between the face plates  21 ,  22  of the hollow extruded frame member  20 . An end portion of the face plates  21 ,  22  of the hollow extruded frame member  20  is mounted on the projection chips  36 ,  36 . The projection chip  36  forms a seat which supports the insertion force of a rotary tool  340 . 
     A width of the raised portion  25  and a width of the raised portion  35  are the same. An end face of the raised portion  35  which is positioned oppositely the raised portion  25  exists in a width of a plate width of the support plate  34 . At a center of the two raised portions  25  and  35  a rotation axial center of the rotary tool  340  of a friction stir joining apparatus  330  is positioned. 
     As shown in FIG. 5, the extruded frame members  10 ,  20 ,  30 ,  40  for constituting the side structure body  201  are mounted on and fixed to a bed  310  of a direction stir joining equipment  300 . A running body  320  runs an upper portion of plural extruded frame members. The running body  320  runs rails  329  of the both side of the bed  310 . To a girder  321  of the running body  320  three friction stir joining apparatuses  330  are lifted down. The friction stir joining apparatus  330  lifts down the rotary tool  340  at a lower end. In the respective friction stir joining apparatus  330  it can run along to the girder  321  and it can carry out a lifting-up and a lifting-down of the rotary tool  340  and further it can carry out singly a rotation of the rotary tool  340 . 
     The respective friction stir joining apparatus  330  has respectively an optical sensor. This optical sensor detects a distance from an apex of the raised portions  25  and  35  and determines an insertion amount of the rotary tool at a predetermined value. Further, the above stated sensor detects a width of the two raised portions  25  and  35  and at a center of the width an axial center of the rotary tool  340  is coincided with. 
     The hollow extruded frame members  20  and  30  are cut off to have the chips  28  and  39  at a start end and a finish end of the joining line. The widths of the chips  28  and  38  have the dimensions in which the support plates  24  and  34  and the raised portions  25  and  35  are provided. The joining is started in the chips  28  and  38  at the start end and the joining is finished in the chips at the finish end. The hollow extruded frame members  10 ,  20 ,  30 ,  40  are cut off to have the window  210  and the inlet and outlet port  220  etc. and to this portions the start end chip  28  and the finish end chip  38  are provided. 
     The hollow extruded frame members  10 ,  20 ,  30 ,  40  are mounted on the bed  310  and the bed  310  is fixed using a tool. When the fixing has completed, the raised portions  25  and  35  of the abutting portions of the hollow extruded frame members  10 ,  20 ,  30 ,  40  is fixed temporary along to the joining line by means of arc welding manner. The most ends of the start end chip  28  and the finish end chip  38  of the joining line are fixed temporary by means of the arc welding. W indicates the temporary fixing welding. In particular the start end temporary fixing welding W is carried out to the upper faces of the raised portions  25  and  35  and the most end portion faces of the longitudinal direction of the hollow extruded frame members. A region of the most end portion face temporary fixing welding W is between the upper faces of the raised portions  25  and  35  and the projection chip  36 . In the temporary fixing welding W, V shape groove is not provided but I shape groove is carried out. 
     Next, in an inner side (the finish end side) from the temporary fixing welding portion W, to the raised portions  25  and  35  a hole  50  is opened using a handy drill. The hole is provided in the starting end chips  28  and  38 . A diameter of the hole  50  is smaller than a diameter of the small diameter portion  341  of the rotary tool  340 . A depth of the cut-off hole  50  is shallower than the insertion depth of the rotary tool  340  (the small diameter portion  341  of the rotary tool  340 ). Namely, the position of the lowest end of the hole  50  is positioned at an upper portion of the lowest end of the small diameter portion  341  of the rotary tool  340 . The hole  50  is formed with an intermediate portion between the two raised portions  25  and  35  at an axial center. The hole  50  is orthogonal to the face plats  21  and  31 . In general, the axial center of the rotary tool  340  is inclined with about three degree angles. Forming a tip end of the small diameter portion  341  of the rotary tool  340  as a center, the side of the large diameter portion  342  of the rotary tool  340  is a rear side of the advancing direction. 
     For example, the diameter of the small diameter portion  341  of the rotary tool  340  is 6.0 mm and the insertion depth is 6.0 mm. The diameter of the hole  50  is 4.0 mm and the position of the lowermost end of the hole  50  is 5.0 mm. 
     Next, the friction stir joining is carried out by rotating the rotary tool  340  and descending it from the upper portion and the rotary tool  340  is inserted to the joining portion. Under in a condition by coinciding the axial center of the rotary tool  340  with the center of the hole  50 , then the rotary tool  340  is descended. The insertion depth of the rotary tool  340  is to up in which the tip end of the small diameter portion  341  of the rotary tool  340  reaches to the projection chip  36 . The lower end of the large diameter portion  342  of the rotary tool  340  is positioned between the outer faces of the face plates  21  and  31  and the apexes of the raised portions  25  and  35 . The small diameter portion  341  of the rotary tool  340  is a screw member. 
     After the rotary tool  340  has inserted to the predetermined depth, the rotary tool  340  is moved along to the joining line. An ordinary operation joining is started. 
     Explaining in detail, at the condition where the axial center of the rotary tool  340  is coincided substantially to the center of the hole  50 , by rotating the rotary tool  340  the rotary tool  340  is descended. At first, the small diameter portion  341  of the rotary tool  340  is contacted to the hollow extruded frame members  20 ,  30 , next the large diameter portion  342  of the rotary tool  340  is contacted to the hollow extruded frame members  20 ,  30 . After the rotary tool  340  has inserted to the predetermined depth, the rotary tool  340  is moved along to the joining line. With this, the friction stir joining starts. 
     The hole  50  is buried with the raised portions  25  and  35  as an original source. When the hole  50  is not buried completely, accompanying with the move of the rotary tool  340  the hole  50  is buried and then a suitable joining condition can be obtained. After the friction stir joining, the chips  28 ,  29  are cut off. The lengths of the chips  28  and  38  are set to the suitable lengths for carrying out the friction stir joining within the chips  28  and  38 . 
     Since the diameter of the hole  50  is smaller than the diameter of the small diameter portion  341  of the rotary tool  340 , the joining is started from the position of the hole  50  and then the lengths of the chips  28  and  38  can be shorten. 
     Since the lower end (the tip end) of the small diameter portion  341  of the rotary tool  340  is inserted deeply to the lower end (the tip end) of the hole  50 , by the existence of the hole  50 , no defects can occur to the lower end of the hole  50 . 
     FIG. 3 shows schematically a change of the insertion force. I is a case of no hole and II is a case of the provision of the hole. The insertion force changes largely immediately after the insertion of the rotary tool  340 . The change of the insertion force will be explained as following. At first, since the small diameter portion  341  of the rotary tool  340  is inserted into a metal having a solid and a low temperature, the insertion force is arisen accompanying with the insertion. After that, accompanying with the insertion, since the metal is softened, accordingly the insertion force lowers. After that, since the large diameter portion  342  of the rotary tool  340  is inserted and is contacted to a new portion, the insertion force is arisen. After that, accompanying with the insertion, since the metal is softened, accordingly the insertion force lowers. After that, the move of the rotary tool  340  is started, the insertion force is arisen again and the insertion force is fallen to a constant value. When the large diameter portion  342  of the rotary tool  340  is inserted, the temperature at a vicinity of the joining portion is raised, the insertion force does not become large in comparison with a rate of the area of the large diameter portion  342  of the rotary tool  340 . 
     In the present invention, since the small diameter portion  341  of the rotary tool  340  is inserted, as shown in II, the insertion force lowers. The maximum value of the insertion force lowers. As a result, the bearing members of the rotary tool  340  can be formed with a compact shape and at a low cost. Further, the plate thickness of the support plates  24  and  34  can be formed thin. Further, the thickness of the projection chip  36  and the thickness of the connection portion between the projection chip  36  and the support plate  34  can be formed thin. As a result, the structure body can be formed with a light weight structure. 
     Further, even the maximum value of the insertion force does not lower, the force for making wide the gap of the joining portion between the hollow extruded frame members  20 ,  30  can be made smaller that that in comparison with the prior art, because of the existence of the hole  50 . For this reason, the length and the depth of the temperate fixing welding W at the end portions of the chips  28  and  38  can be formed small and then the welding can be carried out easily. Further, the above stated temporary fixing welding W can be substituted with one in which the chips  28  and  38  are clamped mechanically. 
     When the joining of the faces of the face plates  21  and  31  has finished, the hollow extruded frame members  20 ,  30  are reversed, similar to the above the temporary fixing welding and the hole opening are carried out, and then the friction stir joining is carried out. Finally, the chips  28  and  38  are cut off. 
     The hollow extruded frame members  20 ,  30  have the window  210 . After the cut-off of the hollow extruded frame members  20 ,  30  with the window shape, when the friction stir joining is carried out, the chips  28  and  38  are provided to the window  210 . These chips  28  and  38  are provided on the start ends of the joining. To these chips  28  and  38  the hole  50  is provided and after the temporary fixing joining, then the friction stir joining is carried out. 
     The shape of the hole  50  may be formed with a taper shape. Further, on the upper end of the hole  50  into which the small diameter portion  341  of the rotary tool  340  is inserted, a hole having a large diameter can be provided. The diameter of the hole  50  of the large diameter portion is smaller than the diameter of the large diameter portion  342  of the rotary tool  340 . Further, the hole  50  may provide only to the diameter portion. Further, plural holes  50  having the small diameter may provide. 
     In the above stated embodiment according to the present invention, the support plate is formed orthogonal with the face plates  31 ,  32 , however when the support plate  34  is supported by the insertion force, the support plate  34  may be formed slant. The shape of the support plate is without distinction of. 
     The technical range of the present invention is not limited to the wordings stated on each claim of claims or the wordings stated on the item of the means for solving the problem and further it refers to the range in which the man belonged to this technical field can replace easily. 
     According to the present invention, the insertion force of the rotary tool  340  can be made small and the good friction stir joining can be carried out.