JP2016144817A - Member joining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a member joining method capable of improving joining strength and being used also for a difficult-to-work member with high strength.SOLUTION: In a member joining method, a steel component 1 and an aluminum component 10 with a through hole 11 are prepared. Using a first metal mold set 20, the steel component 1 is partially swollen while being elastically pressed, and a projection 2 having a first diameter Ds larger than a second diameter De in a final shape insertable into the through hole 11 is formed in the steel component 1. Using a second metallic set 30, the projection 2 is formed to reduce the diameter from the first diameter Ds to the second diameter Ds. Using a third metallic set 40, the projection 2 is crushed in a state of overlapping the steel component 1 and the aluminum component 10 so that the projection 2 is inserted into the through hole 11, and the steel component 1 and the aluminum component 10 are caulked.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for joining members.

  In order to reduce the weight and improve safety of automobiles, a high strength steel sheet called high tension steel is used. Although these high tensile strengths are effective in reducing weight and improving safety, they are still heavy compared to low specific gravity materials such as aluminum. Further, high tension steel has problems such as a decrease in formability due to its high strength, an increase in forming load, and a decrease in dimensional accuracy. In order to solve these problems, in recent years, multi-materials have been used in which extruded products, cast products, and press-formed products using aluminum having a lighter specific gravity than steel plates are used together with steel parts.

  The problem with this multi-materialization is the joining of steel plate parts and light metal parts such as aluminum. In welding technology typified by spot welding, a weak intermetallic compound (IMC) occurs at the interface between the steel plate and aluminum plate, which causes problems, so electromagnetic forming joining, screw fastening represented by bolts and nuts, Friction stir welding (FSW), rivet, self-piercing rivet (SPR), mechanical clinching, bonding, and other joining technologies are put into practical use in any one or a combination of two or more. Has been.

  In Patent Document 1, in a method of connecting metal plate materials to each other, a through hole is formed in one plate material, a hollow protruding portion that fits into the through hole is formed in the other plate material, and the protruding portion is a through hole. And a method of caulking by pressing and crushing is disclosed.

  In Patent Document 2, in a method of joining a first plate-like member having a protrusion and a second plate-like member having a through hole, both members are overlapped and supported so that the protrusion passes through the through hole. A method of supporting by a member and crushing and caulking a protrusion with a pressing member is disclosed.

  Patent Document 3 discloses a method of forming a bottomed cylindrical caulking portion (projection) in two steps in a method of joining a plurality of metal plate-like bodies by caulking.

JP 58-44926 A JP 61-123430 A Japanese Patent Laid-Open No. 61-172631

  Patent Document 1 and Patent Document 2 do not describe any method for forming the protruding portion (projection). In recent years, as represented by automobile parts, press parts are required to be lighter, and materials with high strength and low workability are often used. ) Is not easy to form.

  In the method described in Patent Document 3, the bottom shape of the punch is flat and the height cannot be obtained, and further, the height of the punch is reduced by processing the center of the bottom of the protrusion into an inverted concave shape before crushing. There are many problems. The same applies to the crushing of the protrusion, and the workability of the material may not be able to follow the bending deformation that occurs in the crushed part, and some contrivance is required.

  It is an object of the present invention to provide a method for joining members that can improve joining strength, has high strength, and can be used for difficult-to-work members.

  The present invention provides a first member and a second member provided with a through hole, and uses a first mold set to partially bulge while elastically holding the first member, A protrusion having a first diameter larger than the second diameter in the final shape that can be inserted into the through hole is formed on the first member, and a second mold set is used to move the protrusion from the first diameter to the first diameter. The projection is formed in such a manner that the first member and the second member are overlapped so that the projection is inserted into the through hole. A method for joining members that are crushed to caulk the first member and the second member is provided.

  Since the final-shaped protrusion is formed in two steps, the load on the first member can be reduced, and the protrusion can be formed without causing damage such as cracking to the first member. The protrusion formed in the two-stage process has a sufficient height even when the first member is high in strength and difficult to process, so that a sufficient interlock portion for caulking is expressed when the protrusion is crushed Can be made. As a result, the bonding strength between the first member and the second member can be improved.

  The first member and the second member may be made of materials having different strengths.

  Since it can be caulked and joined regardless of the material, two members having different strengths can be caulked and joined, and it can be made multi-material.

  For example, the first member may be made of steel, and the second member may be made of an aluminum alloy.

  In particular, high-strength steel materials and aluminum alloy materials, which are low specific gravity materials, can be joined and used, and can be used for highly versatile multi-materials that achieve strength and light weight.

  The first mold set may include an initial forming die, a punch, and a first stripper. Further, the punch may be a stepped punch having a first curved surface having a spherical head shape at a central portion and a second curved surface having a curvature different from that of the first curved surface at an outer peripheral portion.

  Breaking the first member can be avoided by using a stepped punch as the punch. When forming a protrusion with a stepped punch, first, the first member is pressed at the apex of the first curved surface having a spherical head shape. Next, a 1st member is pressed with the 2nd curved surface of the outer peripheral part of a stepped punch. Accordingly, the pressing force applied to the first member is dispersed as compared with a normal ball-head shaped punch, and stress concentration can be prevented.

  The shoulder portion of the initial forming die may be chamfered.

  When the shoulder portion of the initial forming die is chamfered, the skirt portion of the protrusion is raised as compared with the case where there is no chamfering, so that the height of the protrusion can be further increased and the bonding strength can be improved.

  The second mold set may include a final molding die and a molding seat. Moreover, the said shaping | molding seat may have a shaping | molding convex part lower than the height of the said protrusion which can be inserted inside the said protrusion.

  The diameter of the final-shaped protrusion can be controlled by the forming convex portion. When there is no molding convex part, there is a possibility that the projection is deformed inward by the final molding die and the diameter is excessively reduced, or the height of the projection is lowered. However, since the first member can be formed so as to be sandwiched between the final forming die and the forming convex portion by providing the forming convex portion, it is possible to prevent these and realize a stable projection forming process.

  A chamfered and inclined collar portion may be provided at the base of the molding convex portion of the molding seat.

  By providing the inclined collar portion, the material is pushed out toward the top of the protrusion, the height of the protrusion can be further increased, and the bonding strength can be improved.

  The second mold set further includes a second stripper, and the second stripper has the final shape in a state in which the skirt portion of the projection formed with an outer diameter larger than the final shape is pressure-restrained in a plane. You may shape | mold.

  Since the skirt portion of the protrusion is pressure-constrained, the material of the wall portion of the protrusion can be prevented from flowing to the skirt portion and lowering the height of the protrusion when the protrusion is formed into a final shape.

  The third mold set may include a presser and a caulking seat. Further, the pusher may have a tapered shape toward the caulking seat, and may have an end at a position corresponding to the center of the protrusion.

  When the presser has a tapered shape, the presser presses the central part of the projection, so that the outer shape can be enlarged while the projection is crushed, the interlock portion can be enlarged, and the bonding strength can be improved.

  The end portion of the pusher may be bitten into the central portion of the protrusion to reduce the thickness.

  By reducing the thickness of the central part of the protrusion, the material of the first member flows out to the side (to the interlock part), so that the interlock part can be enlarged and the bonding strength can be improved.

  The caulking seat may have caulking convex portions that are inserted inside the protrusions.

  Since the caulking seat has the caulking convex portion, the protrusion can be pressed against the caulking convex portion and crushed, so that the caulking can be more reliably performed in a stable state.

  The height of the caulking convex portion of the caulking seat is equal to or greater than the sum of the thickness of the first member and the thickness of the second member, and twice the thickness of the first member. It may be less than the total thickness.

  The caulking convex portion is positioned higher than the second member because the height of the caulking convex portion is equal to or greater than the total thickness of the first member and the second member, and the protrusion is pressed against the caulking convex portion to be crushed. it can. Moreover, excessive crushing can be prevented by being less than the sum of the thickness of the 2nd member and the 2nd thickness of the 1st member. As a result, stable caulking can be realized, and a stable bonding strength can be obtained.

  The outer diameter of the pusher may be equal to or smaller than the outer diameter of the protrusion formed by the second mold set.

  When the outer diameter of the pusher is equal to or smaller than the outer diameter of the protrusion, the tight bending of the first member can be prevented. If the outer diameter of the pusher exceeds the radius of the protrusion, the bent member called close contact bending may be brought into close contact with each other at the bent portion, and bending without a gap may occur. In this case, cracks often occur and can be prevented by using this method.

  The pusher may have an outer peripheral pressing portion that protrudes toward the caulking seat so as to cover the protrusion.

  By providing the outer periphery pressing portion, the first member and the second member can be pressed and crushed prior to the crushing process of the protrusions. Accordingly, the height of the protrusion can be relatively increased, the interlock portion can be enlarged, and the bonding strength can be improved. This is particularly effective in caulking of high-tension steel and ultra-high-tension steel that are difficult to increase the height of the protrusions.

  A counterbore may be provided on the opposite side of the contact surface of the second member with the first member.

  By providing the counterbore, the height of the protrusion can be made relatively higher. Specifically, the height of the projection can be increased by the counterbore at the maximum by the thickness of the second member. Moreover, when crushing a protrusion, since it can crush by the board | plate thickness of a 2nd member at maximum, an interlock part can be expanded and joining strength can be improved.

  According to the joining method of the member of this invention, since the height of the protrusion provided in the 1st member can be made high and the interlock part sufficient for crimping can be expressed, joining strength can be improved. Moreover, this method has high strength and can be used for difficult-to-work members.

Sectional drawing which shows the protrusion after caulking joining of steel parts and aluminum parts. Sectional drawing which shows before formation of the protrusion of the 1st process which concerns on 1st Embodiment. The cross-sectional schematic diagram which shows after formation of the protrusion of the 1st process which concerns on 1st Embodiment. Sectional drawing which shows before final shape shaping | molding of the processus | protrusion of the 2nd process which concerns on 1st Embodiment. Sectional drawing which shows the final shape shaping | molding of the processus | protrusion of the 2nd process which concerns on 1st Embodiment. Sectional drawing which shows before caulking joining of the 3rd process which concerns on 1st Embodiment. Sectional drawing which shows after the crimping joining of the 3rd process which concerns on 1st Embodiment. Sectional drawing of the stepped punch which concerns on 2nd Embodiment. Sectional drawing of the 1st metal mold | die set which concerns on 3rd Embodiment. Sectional drawing before shaping | molding of the 2nd metal mold | die set which concerns on 4th Embodiment. Sectional drawing after shaping | molding of the 2nd metal mold | die set which concerns on 4th Embodiment. Sectional drawing before shaping | molding of the 2nd metal mold | die set which concerns on 5th Embodiment. Sectional drawing after shaping | molding of the 2nd metal mold | die set which concerns on 5th Embodiment. Sectional drawing before shaping | molding of the 2nd metal mold | die set which concerns on 6th Embodiment. Sectional drawing after shaping | molding of the 2nd metal mold | die set which concerns on 6th Embodiment. Sectional drawing before shaping | molding of the 3rd metal mold | die set which concerns on 7th Embodiment. Sectional drawing before shaping | molding of the 3rd metal mold | die set which concerns on 7th Embodiment. Sectional drawing which shows before caulking joining of the 3rd metal mold | die set which concerns on 8th Embodiment. Sectional drawing which shows after caulking joining of the 3rd metal mold | die set which concerns on 8th Embodiment. Sectional drawing which shows before the crimping joining of the 3rd metal mold | die set of another example. Sectional drawing which shows after caulking joining of the 3rd metal mold | die set of another example. Sectional drawing which shows before the crimping joining of the 3rd metal mold | die set of another example. Sectional drawing which shows after caulking joining of the 3rd metal mold | die set of another example. Sectional drawing which shows before crimping joining of another example. Sectional drawing which shows after caulking joining of the 3rd metal mold | die set of another example. Sectional drawing before caulking joining of the 3rd metal mold | die set concerning 9th Embodiment. Sectional drawing before caulking joining of the 3rd metal mold | die set concerning 9th Embodiment. Sectional drawing before caulking joining of the 3rd metal mold | die set of another example. Sectional drawing after caulking joining of the 3rd metal mold | die set of another example. Sectional drawing which shows the steel components which have the counterbore which inclined. The perspective view which crimped and joined the steel bumper beam and aluminum stay which concern on 10th Embodiment. Sectional drawing which shows before formation of the protrusion of a 1st process. Sectional drawing which shows the process in process of 1st process formation. Sectional drawing which shows after formation of the protrusion of a 1st process. Sectional drawing of the steel bumper beam after a 1st process. Sectional drawing which shows before shaping | molding of a 2nd process. Sectional drawing which shows the shaping | molding of a 2nd process. Sectional drawing which shows the 2nd process after shaping | molding. Sectional drawing before the bending process of the steel bumper beam after a 2nd process. Sectional drawing after the bending process of the steel bumper beam after a 2nd process. Sectional drawing which shows before crimping joining of a 3rd process. Sectional drawing which shows after caulking joining of a 3rd process. The perspective view which shows the caulking joining of the hole part of a large dimension. The perspective view which shows the caulking joining of a hat channel and a closing plate.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following description, terms (for example, “upper side”, “lower side”, etc.) representing directions and positions may be used, but these are for facilitating understanding of the invention, and depending on the meaning of these terms. The technical scope of the present invention is not limited. Further, the following description is merely an example of one embodiment of the present invention, and is not intended to limit the present invention, its application, or its use.

(First embodiment)
FIG. 1 shows a cross section of a state in which a steel part (first member) 1 and an aluminum part (second member) 10 are caulked. The steel part 1 is made of steel such as high-tension steel, and a protrusion 2 is provided on a plate-like portion. The aluminum component 10 is made of an aluminum alloy, and a through hole 11 is provided in a plate-like portion. The steel part 1 and the aluminum part 10 are arranged so as to overlap each other with the protrusions 2 inserted through the through holes 11, and are crimped by crushing the protrusions 2 to develop the interlock portions 3.

  With reference to FIG. 2A to FIG. 4B, the first to third steps in the caulking joining method of the present embodiment will be described. In the first step, the protrusions 2 are formed, in the second step, the protrusions 2 formed in the first step are formed into final shapes, and in the third step, the protrusions 2 are crushed to form the steel part 1 and the aluminum part 10. It is tightening.

  As shown in FIG. 2A and FIG. 2B, in the first step, a diameter (first diameter) larger than the diameter (second diameter) De (see FIG. 3B) of the final shape by drawing using the first mold set 20. The diameter 2) of the projection 2 of Ds is formed.

  As shown in FIG. 2A, the first mold set 20 includes a punch 21, an initial forming die 22, and a first stripper 23. The punch 21 has a cylindrical shape, and the upper end 21a in the drawing has a spherical head shape. The initial forming die 22 has a recess 22a into which the punch 21 is partially inserted during press working. The dimensions of the end 21a and the recess 22a of the punch 21 and the initial forming die 22 are determined so that the protrusion 2 is formed to have a diameter Ds larger than the final shape diameter De (see FIG. 3B). The first stripper 23 includes a plate presser 23a for pressing the steel part 1 and a cushion 23b for elastically urging the plate presser 23a toward the initial forming die 22 (upward in the drawing). , Arranged around the punch 21. The steel part 1 is fixed so as not to move by the first stripper 23 and the initial forming die 22.

  As shown in FIG. 2B, in the press working, the end 21a of the punch 21 pushes the steel part 1 into the recess 22a while the first stripper 23 holds the steel part 1 around the punch 21. The protrusion 2 is formed by pressing. The formed protrusion 2 has a generally dome shape and is formed based on the shape of the punch 21.

  As shown in FIGS. 3A and 3B, in the second step, the second mold set 30 is used to mold the protrusion 2 formed in the first step into a final shape diameter De.

  As shown in FIG. 3A, the second mold set 30 includes a final molding die 31 and a molding receiving seat 32. The final shaping die 31 has a recess 31a. The concave portion 31 of the final molding die 31 is smaller than the concave portion 22 a of the initial molding die 22. For this reason, the diameter of the protrusion 2 formed in the first step can be reduced. The molding seat 32 has a support surface 32 a that is flat with respect to the final molding die 31. The steel part 1 is supported by the support surface 32a.

  As shown in FIG. 3B, the protrusion 2 formed in the first step is inserted into the recess 31a of the final forming die 31 by the forming process, whereby the protrusion 2 is reduced in diameter and formed into the final shape diameter De. . At this time, the protrusion 2 is only reduced in diameter, and the height is not substantially changed.

  As shown in FIGS. 4A and 4B, in the third step, the steel part 1 and the aluminum part 10 are caulked using a third mold set 40.

  As shown in FIG. 4A, the third mold set 40 includes a pusher 41 and a crimping seat 42. The presser 41 has a flat pressing surface 41a on the bottom surface, and the protrusion 2 is crushed toward the crimping seat 42 by the pressing surface 41a. The crimping seat 42 has a support surface 42 a that is flat with respect to the presser 41 on the upper surface. The steel part 1 and the aluminum part 10 are disposed so as to overlap each other with the protrusion 2 inserted through the through hole 11 and supported by the support surface 42a.

  As shown in FIG. 4B, the steel part 1 and the aluminum part 10 are caulked and joined by lowering the pusher 41 and crushing the protrusions 2. 4A and 4B, a plate presser 43 may be arranged on the outer periphery of the presser 41. As shown in FIG. Stable caulking is possible by lowering the plate holder 43 in advance and restraining the skirt portion 2a of the protrusion 2 via the aluminum part 10, and lowering the pusher 41 and crushing the protrusion 2 in this state.

  In the caulking process, it is important to increase the height of the protrusion 2 provided on the steel part 1 in order to develop a sufficient interlock part 3. From the viewpoint of performance and manufacturing cost.

  According to the method of the present embodiment, since the final-shaped protrusion 2 is formed in a two-step process, the protrusion 2 can be formed with a small number of man-hours without causing damage such as cracks in the steel part 1. Furthermore, since the protrusion formed in the two-stage process has a sufficient height even when the steel part 1 is high in strength and difficult to process, a sufficient interlock portion for caulking when it is crushed. 3 can be expressed. For this reason, the joint strength between the steel part 1 and the aluminum part 10 can be improved.

  In addition, since caulking can be performed regardless of the material, two members having different strengths can be caulked and bonded, so that multi-materials can be achieved. In the present embodiment, a steel part 1 made of high strength steel and an aluminum part 10 made of an aluminum alloy material, which is a low specific gravity material, are joined to make a highly versatile multimaterial that achieves strength and light weight. . However, the materials of the members to be joined are not limited to these, and members of various materials can be used.

  Next, 2nd and 3rd embodiment regarding the alternative of a 1st process is described.

(Second Embodiment)
The bonding method of this embodiment shown in FIG. 5 is the same as that of the first embodiment of FIGS. 2A to 4B except for the fact that the punch 21 is replaced with the stepped punch 24. Therefore, the same components as those shown in FIGS. 2A to 4B are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 5, the shape of the stepped punch 24 of the first mold set 20 of the present embodiment is different from the first curved surface 24a having a spherical head shape at the central portion and the first curved surface 24a at the outer peripheral portion. It has the 2nd curved surface 24b of curvature. However, in order to increase the height of the protrusion 2, it is preferable to use a stepped punch 21 as shown in FIG.

  Thus, the breakage of the steel part 1 can be avoided by using the stepped punch 21 as the punch 21. When the projection 2 is formed by the stepped punch 21, the steel part 1 is first pressed by the top of the first curved surface 24a having a spherical head shape. Next, the steel part 1 is pressed by the second curved surface 24 b of the outer peripheral portion of the stepped punch 21. Therefore, the pressing force applied to the steel part 1 is dispersed as compared with the normal ball-head shaped punch 21, and stress concentration can be prevented.

(Third embodiment)
The joining method of this embodiment shown in FIG. 6 is the same as that of the first embodiment of FIGS. 2A to 4B except for the portion related to the initial forming die 22. Therefore, the same components as those shown in FIGS. 2A to 4B are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 6, the shoulder 22b of the initial molding die 22 of the first mold set 20 of the present embodiment is chamfered. However, the chamfering is not limited to the C surface, and the chamfering may be performed at any angle.

  Since the shoulder 22b is chamfered, the skirt 2a (see FIG. 2B) of the protrusion 2 is lifted compared to the case where there is no chamfering, so that the height of the protrusion 2 can be further increased and the bonding strength is improved. it can.

  Next, fourth to sixth embodiments relating to alternatives of the second step will be described.

(Fourth embodiment)
7A and 7B is the same as that of the first embodiment shown in FIGS. 2A to 4B except for the portion related to the molding seat 32. Therefore, the same components as those shown in FIGS. 2A to 4B are denoted by the same reference numerals and description thereof is omitted.

  As shown to FIG. 7A, the shaping | molding receiving seat 32 of the 2nd metal mold | die set 30 of this embodiment is provided with the shaping | molding convex part 32b. The forming convex portion 32 b is cylindrical and extends vertically upward toward the final forming die 31. The molding convex part 32 b is inserted into the protrusion 2. As shown in FIG. 7B, during the forming process, the forming protrusion 32 b supports the steel part 1 from the inside and forms the protrusion 2 so as to sandwich the steel part 1 together with the final forming die 31.

  According to this method, the final shape diameter De (see FIG. 3B) of the protrusion 2 can be controlled by the molding convex portion 32b. When there is no shaping | molding convex part 32b, there exists a possibility that the processus | protrusion 2 may deform | transform inside by the last shaping | molding die 31, and a diameter may be reduced too much and the height of the processus | protrusion 2 may become low. However, by providing the molding convex portion 32b, the steel part 1 can be molded so as to be sandwiched between the final molding die 31 and the molding convex portion 32b, so that these can be prevented and a stable projection molding process can be realized. The molding convex portion 32b preferably has a diameter of 2/3 or less compared to the punch 21 (see FIGS. 2A and 2B) of the first mold set 20, and thus a more stable molding process is possible.

(Fifth embodiment)
The joining method of this embodiment shown in FIGS. 8A and 8B is the same as that of the fourth embodiment of FIGS. 7A and 7B except for the portion related to the second stripper 33. Therefore, the same components as those shown in FIGS. 7A and 7B are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 8A, the second mold set 30 of this embodiment includes a second stripper 33. The second stripper 33 includes a plate presser 33 a for pressing the steel part 1 and a cushion 33 b for urging the plate presser 33 a toward the final forming die 31. The cushion 33b has one end connected to the final molding die 31 and the other end connected to the plate presser 33a. Accordingly, the second stripper 33 is movable in the vertical direction in the figure, and the plate presser 33a presses and fixes the steel part 1 against the support surface 32a of the molding seat 32.

  When the final molding die 31 is lowered to reduce the outer diameter Ds (see FIG. 2B) of the protrusion 2 to the final shape diameter De (see FIG. 3B), the material of the wall 2b of the protrusion 2 is the base of the protrusion 2. In some cases, the height may be reduced by escaping to the portion 2a. Therefore, as shown in FIG. 8A, before the final molding die 31 is lowered, the plate holder 23a is arranged on the outer periphery of the final molding die 31, and the bottom portion 2a of the protrusion 2 is suppressed by the plate holder 23a. More preferably, the final forming die 31 is lowered to the final shape as shown in 8B.

  By doing so, the skirt portion 2a of the protrusion 2 is pressed and restrained, so that when the protrusion 2 is formed into a final shape, the material of the wall portion 2b of the protrusion 2 flows to the skirt portion 2a and the protrusion 2 It is possible to prevent the height from being lowered.

(Sixth embodiment)
9A and 9B is the same as the fourth embodiment of FIGS. 8A and 8B except for the portion related to the molding seat 32. Therefore, the same components as those shown in FIGS. 8 and 8B are denoted by the same reference numerals, and the description thereof is omitted.

  As shown to FIG. 9A, the shaping | molding receiving seat 32 of the 2nd metal mold | die set 30 of this embodiment is provided with the collar part 32c which inclined to the root of the shaping | molding convex part 32b. The collar portion 32 c is provided over the entire circumference of the molding convex portion 32.

  According to this method, when the projection 2 is formed at the bottom dead center of the molding by the molding receiving seat 32, the material is pushed out to the top 2c of the projection 2 by the inclined collar portion 32c, and the height of the projection 2 is further increased.

  Next, the seventh to ninth embodiments relating to the third process alternative will be described.

(Seventh embodiment)
10A and 10B is the same as the first embodiment of FIGS. 2A to 4B except for the portion related to the caulking seat 42. Therefore, the same components as those shown in FIGS. 2A to 4B are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 10A, the caulking receiving seat 42 of the third mold set 40 of the present embodiment includes a caulking convex portion 42b. The caulking convex portion 42 b has a columnar shape and extends vertically upward toward the pusher 41. The caulking convex portion 42 b is inserted into the protrusion 2. As shown in FIG. 10B, during the caulking process, the caulking convex portion 42b supports the steel part 1 from the inside and is caulked and joined.

  Thus, by providing the crimping convex part 42b, the uniform deformation | transformation of the steel components 1 is assisted, and stable crimping joining is realizable.

  Further, as shown in FIG. 10A, the outer diameter D1 of the pusher 41 used for crushing the protrusion 2 is equal to or smaller than the outer diameter D2 of the protrusion 2 formed by the second mold set 30 (D1 ≦ D2). It is preferable.

  Thereby, the tight bending of the steel part 1 can be prevented. When the outer diameter D1 of the pusher 41 is larger than the outer diameter D2 of the protrusion 2 (D1> D2), when the pressing part 41 including the curved part 3a of the protrusion 2 is pressed by the pusher 41, a bent member called contact bending at the curved part 3a However, there is a case where bending occurs in a tight contact with the curved portion and no gap exists. In this case, it is known that cracks often occur. Therefore, the crack can be prevented by defining the outer diameter D1 of the pusher 41.

  Further, as shown in FIG. 10B, the height Hh of the crimping convex portion 42b of the crimping seat 42 is equal to or greater than the sum of the thickness Hs of the steel part 1 and the thickness Ha of the aluminum part 10 (Hs + Ha ≦ Hh). It is preferable to use a caulking seat 42 that is twice the thickness of the steel part 1 and the total thickness of the aluminum part 10 (Hh ≦ 2 × Hs + Ha).

  As a result, the height Hh of the crimping protrusion 42b is equal to or greater than the sum of the thickness Hs of the steel part 1 and the thickness Ha of the aluminum part 10 (Hs + Ha ≦ Hh), so that the upper surface 42c of the crimping protrusion 42b is made of aluminum. It is positioned higher than the part 10. Therefore, the protrusion 2 can be pressed and crushed against the crimping convex portion 42b. Moreover, excessive crushing is prevented by the fact that the height Hh of the crimping convex portion 42b is less than the total of the thickness Hs of the steel part 1 and the thickness Ha of the aluminum part 10 (Hh ≦ 2 × Hs + Ha). it can. As a result, stable caulking can be realized, and a stable bonding strength can be obtained.

(Eighth embodiment)
In the joining method of the present embodiment shown in FIGS. 11A and 11B, the configuration other than the portion related to the pusher 41 is the same as that of the seventh embodiment of FIGS. 10A and 10B. Therefore, the same components as those shown in FIGS. 10A and 10B are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 11A, in the presser 41 of the third mold set 40 of the present embodiment, the center of the pressing surface 41a bulges toward the crimping seat 42 (downward in the drawing). The bulging shape of the presser 41 is formed in accordance with the top (center) 2 c of the protrusion 2. Therefore, as shown in FIG. 11B, the outer shape can be enlarged while the protrusion 2 is crushed.

  The swell shape of the pusher 41 can be variously considered. For example, the shape of a truncated cone as shown in FIGS. 12A and 12B or a hemispherical shape as shown in FIGS. 13A and 13B may be used.

  According to this method, since the pusher 41 presses the central portion 2c of the projection 2 first, the outer shape can be enlarged while the projection 2 is crushed, the interlock portion 3 can be enlarged, and the bonding strength can be improved.

  Further, as shown in FIGS. 14A and 14B, when the presser 41 has a conical shape, the upper end 42c of the caulking convex portion 42b of the caulking seat 42 is utilized, and the lower end portion 41c in the conical shape is shown. Can be made to bite into the central portion 2c of the protrusion 2 to reduce the thickness.

  According to this method, since the material of the steel part 1 flows out to the side (to the interlock part 3) by reducing the central part 2c of the protrusion 2, the interlock part 3 can be enlarged and the joint strength is improved. it can.

(Ninth embodiment)
The joining method of this embodiment shown in FIGS. 15A to 16B is the same as the seventh embodiment of FIGS. 10A and 10B except for the portion related to the outer peripheral pressing portion 41b. Therefore, the same components as those shown in FIGS. 10A and 10B are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 15A, the presser 41 of the third mold set 40 of this embodiment includes an outer peripheral pressing portion 41b. The outer peripheral pressing portion 41 b is provided on the outer peripheral portion of the pusher 41 and protrudes downward so as to embrace the outer peripheral portion of the protrusion 2.

  According to this method, by providing the outer periphery pressing portion 41b, the steel part 1 and the aluminum part 10 can be pressed and crushed prior to the crushing process of the protrusion 2 as shown in FIG. 15B. Accordingly, the height of the protrusion 2 can be relatively increased, the interlock portion 3 can be enlarged, and the bonding strength can be improved. This is particularly effective in the caulking process of high-tension steel material or ultra-high-tension steel material in which it is difficult to increase the height of the protrusion 2.

  As shown in FIGS. 16A and 16B, the inner diameter of the outer peripheral pressing portion 41b may be enlarged. By enlarging the inner diameter, deformation of the edge 11a of the through hole 11 of the aluminum part 10 can be reduced. Thus, you may change the internal diameter of the outer periphery press part 41b as needed.

  In addition, as shown in FIG. 17, the counterbore part 12 is provided in the edge part 11a of the through-hole 11 on the opposite side of the contact surface with the steel part 1 of the aluminum part 10 through all the 1st-3rd processes. Also good. The cross-sectional shape of the inclined surface at this time is not particularly limited, and may be linear or curvilinear. For example, the bonding strength is taken into consideration for the inclination angle θ (45 degrees in this embodiment) shown in the figure. And decide.

  Thus, by providing the counterbore part 12, the height of the protrusion 2 can be made relatively higher. Specifically, the height of the protrusion 2 can be increased by the counterbore at the maximum by the thickness of the aluminum component 10. Further, when crushing the protrusion 2, it can be crushed as much as the plate thickness of the aluminum part 10 at the maximum, so that the interlock portion 3 can be enlarged and the bonding strength can be improved.

  Next, an example in which the present invention is applied to a bumper that is one of automobile parts will be described in a tenth embodiment.

(10th Embodiment)
As shown in FIG. 18, in this embodiment, a square tubular aluminum stay 10 is joined to a steel bumper beam 1 having a cross section of a hat channel by multi-point caulking.

  In implementation, the steel bumper beam 1 is a 980 MPa class cold-rolled steel plate having a thickness of 1.4 mm, the side wall 1 a has a height of 70 mm, the bottom 1 b has a width of 120 mm, and the overall length is It is molded into a 1000 mm hat channel mold. The protrusions 2 are provided on the side wall portion 1a on one side of the steel bumper beam 1 at six places, a total of 12 places on both sides. The aluminum stay 10 is made of an aluminum alloy of A6063, and is a pipe type having a square cross section with a plate thickness of 3 mm, an inner dimension of 120 mm, and a length of 150 mm. The aluminum stay 10 is processed into a shape that allows both side walls 1a of the steel bumper beam 1 to be sandwiched from the outside. The aluminum stay 10 is provided with a through hole 11 through which the projection 2 is inserted, and is joined to the through hole 11 by caulking the projection 2.

  The entire caulking process will be described with reference to FIGS. 19A to 22B.

  19A to 19D show a process of forming the protrusion 2 as the first process. As shown in FIG. 19A, a spherical head-shaped round bar (punch) 21 capable of forming the protrusion 2, a first stripper 23 having a plate holder 23 a and a cushion 23 b, and the spherical head-shaped round bar 21 can be inserted. A first mold set 20 including an initial molding die 22 provided with a recess 31a is prepared. A steel plate (steel bumper beam) 1 is set in the first mold set 20, and as shown in FIG. 19B, the steel plate 1 is pressed by a plate holder 23a elastically biased toward the initial forming die 22 by a cushion 23b. To fix. Then, as shown in FIG. 19C, the protrusion 2 is formed by the ball-shaped round bar 21 and the joining flange 1c is bent. FIG. 19D shows the cross-sectional shape of the steel plate 1 after the formation of the protrusions 2.

  20A to 20C show a process of forming the protrusion 2 as the second process. As shown in FIG. 20A, a final molding die 31 provided with a molding seat 32 having a flat support surface 32a and a concave portion 31a having a smaller diameter than the concave portion 22a of the initial molding die 22 (see FIGS. 19A to 19C). Then, a second mold set 30 including a second stripper 33 having a plate presser 33a and a cushion 33b is prepared. The steel plate 1 after the formation of the protrusions 2 is set in the second mold set 30, that is, placed on the support surface 32a, and is elastically moved toward the final forming die 31 by the cushion 33b as shown in FIG. 20B ( The steel plate 1 is fixed by the pressed plate retainer 33a (downward in the figure). Then, as shown in FIG. 20C, the protrusion 2 is formed to a final shape diameter by the final forming die 31 and the forming receiving seat 32.

  21A and 21B show a process of forming the steel plate 1 into a hat channel shape. As shown in FIG. 21A, a lower mold 51 for supporting the steel plate 1 after the formation of the protrusions 2 and an upper mold 50 for bending are prepared. The lower mold 51 includes a convex portion 51a having a flat upper surface 51b and a flat side surface 51c. The upper mold 50 includes a concave portion 50b corresponding to the convex portion 51a. As shown in FIG. 21B, the bending process is performed such that the upper die 50 is lowered, the steel plate 1 is bent by the shoulder 50a, and the steel plate 1 is partially sandwiched by the convex portions 51a and the concave portions 51b. A steel bumper beam 1 having a channel cross section is completed. At this time, it is more preferable that the upper die 50 incorporates a leading pad (not shown) to prevent the movement (displacement) of the steel plate 1 due to bending.

  22A and 22B show a caulking process of the steel bumper beam 1 and the aluminum stay 10. As shown to FIG. 22A, the 3rd metal mold | die set 40 provided with the crimping seat 42 which can fit the steel bumper beam 1, and the presser 41 for caulking is prepared. As shown in FIG. 22A, the steel bumper beam 1 is fitted to and supported by a crimping seat 42. The aluminum stay 10 is disposed so as to overlap the steel bumper beam 1 with the protrusion 2 inserted into the through hole 11. Next, as shown in FIG. 22B, the pusher 41 is lowered to caulk the six protrusions 2 of the side wall 1 a and the through holes 11 of the aluminum stay 10. Thereafter, the steel bumper beam 1 is turned upside down to complete the caulking process at six locations on the opposite side wall 1a.

  Further, as shown in FIG. 23, according to this method, large-scale caulking in which the diameter of the protrusion 2 is increased is also possible. Furthermore, as shown in FIG. 24, the present invention can also be applied to joining of the hat channel 4 and the closing plate 15. If this method is used in this way, it is possible to easily join different types of members such as the steel part 1 and the aluminum part 10.

1 Steel parts (steel bumper beam)
DESCRIPTION OF SYMBOLS 1a Side wall part 1b Bottom part 1c Flange 2 Protrusion 2a Bottom part 2b Wall part 2c Top part (center part)
3 Interlocking part 3a Bending part 4 Hat channel 10 Aluminum parts (aluminum stay)
DESCRIPTION OF SYMBOLS 11 Through hole 11a Edge part 12 Counterbore part 15 Closing plate 20 1st metal mold | set 21 Punch 21a End part 22 Initial shaping | molding die 22a Recessed part 22b Shoulder part 23 First stripper 23a Plate presser 23b Cushion 24 Stepped punch 24a First curved surface 24b Second curved surface 30 Second mold set 31 Final molding die 31a Concavity 32 Molding receiving seat 32a Support surface 32b Molding convex part 32c Brim 33 Second stripper 33a Plate presser 33b Cushion 40 Third mold set 41 Presser 41a Press Surface 41b Outer peripheral pressing portion 41c End portion 42 Crimping seat 42a Support surface 42b Caulking convex portion 42c Upper surface 43 Plate presser 50 Upper mold 50a Shoulder portion 50b Recessed portion 51 Lower mold 51a Protruding portion 51b Upper surface 51c Side surface

Claims (18)

Preparing a first member and a second member provided with a through hole;
A projection having a first diameter larger than the second diameter in the final shape that can be inserted into the through hole by using the first mold set and partially expanding while elastically holding the first member. Is formed on the first member,
Using a second mold set, the protrusion is molded to reduce the diameter from the first diameter to the second diameter,
Using a third mold set, the first member and the second member are crushed by crushing the protrusion in a state where the first member and the second member are overlapped so that the protrusion is inserted into the through hole. The method of joining the members.   The method for joining members according to claim 1, wherein the first member and the second member are made of materials having different strengths.   The method for joining members according to claim 1, wherein the first member is made of steel, and the second member is made of an aluminum alloy.   4. The member joining method according to claim 1, wherein the first mold set includes an initial forming die, a punch, and a first stripper. 5.   5. The method for joining members according to claim 4, wherein the punch is a stepped punch having a first curved surface having a spherical head shape at a central portion and a second curved surface having a curvature different from that of the first curved surface at an outer peripheral portion. .   The method for joining members according to claim 4 or 5, wherein a shoulder portion of the initial forming die is chamfered.   The method of joining members according to any one of claims 1 to 6, wherein the second mold set includes a final forming die and a forming seat.   The method for joining members according to claim 7, wherein the molding seat has a molding convex portion lower than a height of the projection that can be inserted inside the projection.   The joining method of the member of Claim 8 with which the base part of the said shaping | molding convex part of the said shaping | molding seat is provided with the chamfered and inclined collar part.   The second mold set further includes a second stripper, and the second stripper has the final shape in a state in which the skirt portion of the projection formed with an outer diameter larger than the final shape is pressure-restrained in a plane. The method for joining members according to claim 7, wherein the member is molded into a shape.   The member joining method according to any one of claims 1 to 10, wherein the third mold set includes a presser and a caulking seat.   The method of joining members according to claim 11, wherein the pusher has a tapered shape toward the caulking seat, and has an end portion at a position corresponding to a central portion of the protrusion.   The member joining method according to claim 12, wherein the end portion of the pusher is bitten into the central portion of the protrusion to reduce the thickness.   The method for joining members according to any one of claims 11 to 13, wherein the crimping seat has a crimping protrusion inserted inside the protrusion.   The height of the caulking convex portion of the caulking seat is equal to or greater than the sum of the thickness of the first member and the thickness of the second member, and twice the thickness of the first member. The method for joining members according to claim 14, wherein the joining method is equal to or less than a total thickness.   The member joining method according to any one of claims 11 to 15, wherein an outer diameter of the presser is equal to or smaller than an outer diameter of the protrusion formed by the second mold set.   The method of joining members according to any one of claims 11 to 16, wherein the pusher includes an outer peripheral pressing portion that protrudes toward the caulking seat so as to cover the protrusion.   The method of joining members according to any one of claims 1 to 17, wherein a counterbore portion is provided on the opposite side of the contact surface of the second member with the first member.

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