Metal sheet crimping die and crimped metal sheet

Abstract

The present invention provides a mold that enables the joining of metal plates with high bonding strength, and the joined metal plates. [Solution] The crimping die according to the present invention has a die having a recess and a punch plate having a protrusion, the inner wall surface of the recess has three corner curved wall surfaces provided on a convex curved surface radiating in three directions from the center, and an intermediate curved wall surface formed between each corner curved wall surface and the adjacent corner curved wall surface, the bottom surface of the recess has an upwardly projecting protrusion surface made of a surface that is spaced apart from the inner wall surface, the protrusion consists of a protrusion having a three-pronged surface extending in three directions and a cylindrical punch positioned between each protrusion, the cylindrical punch is positioned to press the metal plate on the inside of the intermediate curved wall surface.

Description

Technical Field

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[0001] The present invention relates to a caulking die for a metal plate having high joint strength and a caulked metal plate.

Background Art

[0002] Methods for joining metal plates include joining with fasteners such as bolts and rivets, and joining methods such as welding. However, joining with fasteners has a problem that the fasteners must be prepared separately, resulting in high costs. In the case of welding, joining of dissimilar metals is difficult, and there is a problem that the metal may be thermally deformed because the metal is heated to a high temperature. On the other hand, caulking can be carried out at a low cost, can join dissimilar metals, and can be processed simultaneously during the pressing process of the metal plate, so that joining can be performed without going through a separate joining process. Therefore, caulking is applied in various industrial fields.

[0003] However, caulking has a problem that the joint strength is generally lower than that of joining methods using fasteners or spot welding methods. For example, the caulking joint strength when joining with a caulking device using a general round punch and die is only about 20% to 40% of the strength of spot welding.

[0004] Therefore, a caulking method using a three-pronged punch has been proposed. For example, by using a three-pronged columnar punch and a movable blade that moves in three directions, a caulking joint portion extending in three directions is formed, so that the length of the side wall portion becomes relatively long, and a joint portion having high joint strength can be obtained by a simple method (Patent Document 1).

[0005]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0006] The present invention further aims to provide a mold that enables the joining of metal plates having high bonding strength, and the joined metal plates. [Means for solving the problem]

[0007] To achieve the above-mentioned objectives, the present invention employs the following means.

[0008] The crimping joint die according to the present invention is In a mold for joining multiple metal plates by plastically deforming them through pressing, the metal plates are stacked and arranged between a die having a recess and a punch plate having a convex portion. The inner wall surface of the recess has three corner curved wall surfaces provided on a convex curved surface radiating in three directions from the center, and an intermediate curved wall surface formed between each corner curved wall surface and the adjacent corner curved wall surface. The bottom surface of the recess has an upwardly projecting surface that is made of a surface that is spaced apart from the inner wall surface. The aforementioned protrusion consists of a projection having a three-pronged surface extending in three directions, and a cylindrical punch positioned between each of the aforementioned projections. The cylindrical punch is characterized by being positioned to press the metal plate on the inside of the intermediate curved wall surface.

[0009] The crimping die according to the present invention presses and joins a metal plate using three protrusions having a three-pronged surface extending in three directions and three cylindrical punches, resulting in six locking points, which allows for a strong bond between metal plates. Furthermore, the protruding surfaces formed in the recesses efficiently move the metal to the locking points, ensuring a secure crimped joint.

[0010] Furthermore, the protruding surface may be provided with a burring punch whose tip is shaped like a bullet or tapered to create a burring hole, and the protruding portion may be provided with a burring punch hole in the center of the protruding portion into which the burring punch is inserted during pressing. By adopting such a configuration, a burring hole can be provided in the center of the crimped joint.

[0011] Furthermore, in the crimping die according to the present invention, the protruding surface may be characterized by having a shape that is offset inward from the inner wall surface of the recess. By adopting such a configuration, the protruding surface is positioned towards the center, the metal can be plastically deformed to protrude outward, and a strong crimped joint can be provided on the outer circumference.

[0012] Furthermore, in the crimping die according to the present invention, the cylindrical punch may be characterized by having a protruding length longer than the protruding portion. By adopting such a configuration, the initial shape is determined by first pressing multiple metal plates with the cylindrical punch, and once a certain amount of pressure is applied, the protruding portion holds down the metal plates, preventing the metal from plastically deforming in directions other than the outer circumference. By causing the metal to plastically deform so that it protrudes outwards from the outer circumference of the cylindrical punch, a stronger crimped joint can be provided.

[0013] Furthermore, in the crimping die according to the present invention, the cylindrical punch may be positioned in a through hole formed in the punch plate, the hole having a diameter larger than the diameter of the cylindrical punch. By adopting this configuration, the tip of the cylindrical punch can be moved horizontally. This allows the cylindrical punch to press the metal plate at the optimal position, reducing the possibility of excessive force being applied to a part of the metal plate, which could result in holes or tears.

[0014] Furthermore, the crimping die according to the present invention may be characterized in that, when the die and the punch plate are closed, the distance between the cylindrical punch and the protruding surface is less than or equal to half the thickness of the multiple metal plates to be joined. By adopting such a configuration, a stronger crimped joint can be provided by plastically deforming the cylindrical punch so that the metal protrudes outwards on the outer circumference.

[0015] Furthermore, the present invention provides a joined metal plate, which is joined by the crimping die described above, characterized in that the crimped joint consists of three deeply pressed crimped joints and three shallow crimped joints formed between these deep crimped joints. Such a metal plate can be made into a metal plate with high joint strength.

[0016] Furthermore, in the present invention, in metal plates joined by a crimping die, The crimped joint provides a joined metal plate characterized by having three deeply pressed crimped joints, three shallow crimped joints formed between these deep crimped joints, and a burring hole formed in the center thereof. The joined metal plate is also characterized in that a screw is fastened in the burring hole. Since a burring hole can be provided in the crimped joint, a screw can be fastened in the burring hole as needed, enabling a stronger bond. [Effects of the Invention]

[0017] The crimping die according to the present invention provides a die that enables the joining of metal plates having high joint strength. [Brief explanation of the drawing]

[0018] [Figure 1] Figure 1 is a top perspective view of the crimping die 100 according to the first embodiment. [Figure 2] Figure 2 is a top view of the die recess 20 formed in the die 10 according to the first embodiment. [Figure 3] FIG. 3 is a bottom-side perspective view of the caulking joint mold 100 according to the first embodiment. [Figure 4] FIG. 4 is a bottom view of the convex portion formed on the punch plate 50 according to the first embodiment. [Figure 5] FIG. 5 is a schematic diagram showing the positional relationship between the die recess 20 and the convex portion of the caulking joint mold 100 according to the first embodiment. [Figure 6] FIG. 6A is a cross-sectional view showing the state where the caulking joint mold 100 according to the first embodiment is open, and FIG. 6B is a cross-sectional view showing the closed state. [Figure 7] FIG. 7A is a photograph showing the front side of the metal plate joined by the caulking joint mold 100 according to the first embodiment, and FIG. 7B is a photograph showing the back side of the metal plate joined by the caulking joint mold 100 according to the first embodiment. [Figure 8] FIG. 8 is a cross-sectional view of the metal plate joined by the caulking joint mold 100 according to the first embodiment. [Figure 9] FIG. 9 is a top-side perspective view of the caulking joint mold 100 according to the second embodiment. [Figure 10] FIG. 10 is a bottom view of the convex portion formed on the punch plate 50 according to the first embodiment. [Figure 11] FIG. 11 is a photograph showing the front side of the metal plate joined by the caulking joint mold 100 according to the first embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments and drawings described below are examples of a part of the embodiments of the present invention and are not used for the purpose of limiting these configurations. Also, corresponding components in each figure are denoted by the same or similar reference numerals. In the present invention, as shown in FIG. 1, the upper direction refers to the direction toward the punch plate 50 with respect to the die 10, and the lower direction refers to the opposite side.

[0020] (First Embodiment) The metal plate crimping die 100 according to the first embodiment is a die for crimping and joining metal plates, as shown in Figure 1, which stacks two or more metal plates 90 (see Figure 6) between a die 10 having a recess and a punch plate 50 having a convex portion, and presses them together with the die 10 and the punch plate 50 to plastically deform them.

[0021] As shown in Figure 1, the die 10 has a die recess 20 formed on its upper surface. As shown in Figure 2, the inner wall surface 25 of the die recess 20 has three corner curved wall surfaces 21 formed at positions corresponding to three equally angled directions, each curved convexly toward the outer periphery. The corner curved wall surfaces 21 have a configuration that combines a wall surface 21a with a large curvature on the central side and wall surfaces 21b with a small curvature on both sides of this wall surface 21a. Between these corner curved wall surfaces 21 and adjacent corner curved wall surfaces 21, three arc-shaped intermediate curved wall surfaces 22 are formed, which are curved convexly toward the outer periphery. Thus, the curved inner wall surface 25 of the die recess 20 is formed by a total of six convexly curved inner wall surfaces 25 toward the outer periphery, consisting of the three corner curved wall surfaces 21 in three directions and the three intermediate curved wall surfaces 22 formed between them. The bottom surface 26 of the die recess 20 has a protruding surface 27 that projects upward. The protruding surface 27 is provided in the center so as to be spaced apart from the inner wall surface 25. By providing this protruding surface 27, when the metal plate 90 is pressed, the metal is less likely to plastically deform toward the center, and the metal is more likely to plastically deform toward the outer periphery, thereby effectively forming a crimped joint. Preferably, the planar shape of the protruding surface 27 is offset inward at a constant interval relative to the top view shape of the inner wall surface 25. Furthermore, it is preferable that the protruding height of the protruding surface 27 from the bottom surface 26 is less than or equal to the stacked thickness of the metal plates 90 to be joined.

[0022] As shown in Figure 3 or Figure 4, the punch plate 50 has a protruding portion consisting of a three-pronged projection 51 extending in three directions from the center, and cylindrical punches 54 positioned between each projection 51. The shape of the projection 51 is formed with extensions 51a that radiate outwards in a three-pronged manner from the center, and the tips of the extensions 51a are formed to be wider, giving the overall shape roughly resembling a clover leaf. The projection 51 is tapered so that its area decreases toward the lower surface, making it easier to peel off the metal plate after punching. Between these extensions 51a and adjacent extensions 51a, there is a cylindrical punch 54. The cylindrical punch 54 is positioned in a cylindrical through hole 55 provided in the punch plate 50. The through hole 55 is cylindrical with a diameter slightly larger than the diameter of the cylindrical punch 54, and is provided so that the cylindrical punch 54 can move slightly in the horizontal direction. Furthermore, the protruding length of the cylindrical punch 54 is set to be longer than the protruding length of the protruding portion 51. By manufacturing it in this way, the cylindrical punch 54 reliably presses the metal plate, and because the extended portion 51a is tapered and has a height difference, material can be reliably flowed between the cylindrical punch 54 and the extended portion 51a.

[0023] When the die recess 20, the protruding portion 51 of the punch plate 50, and the cylindrical punch 54 thus created are attached to the mold, as shown in Figure 5 (the protruding portion 51 and the cylindrical punch 54 are shown as dotted lines), when viewed from above, the tip of the extended portion 51a is positioned inside the corner curved wall surface 21, and the cylindrical punch 54 is positioned inside the intermediate curved wall surface 22.

[0024] The crimping die 100 thus manufactured joins the metal plates 90 as follows. While the explanation uses two metal plates as an example, the joining method remains the same even with three or more plates, only the number of stacked metal plates increases. First, as shown in Figure 5, the die 10 and punch plate 50 are attached to the press machine so that the protrusions 51 of the punch plate 50 and the cylindrical punch 54 are positioned relative to the die recess 20. As shown in Figure 6, two metal plates 90 to be joined are placed on top of each other in relation to the attached crimping die 100. By pressing the crimping die 100 in this state, the protrusions 51 and cylindrical punch 54 push the two metal plates 91 and 92 into the die recess 20 from above. Furthermore, by lowering the punch plate 50 and pushing the protrusions 51 and cylindrical punch 54 into the metal plates 90, the lower metal plate 92 comes into contact with the bottom surface of the die recess 20, crushing the material. At this time, the protrusion 51 contacts the upper metal plate 91, causing plastic deformation of the metal below the protrusion 51. Simultaneously, the cylindrical punch 54 also presses against the metal plate 90, causing plastic deformation of the metal. However, as shown in Figure 7, at least a portion of the metal below the protrusion 51 and the cylindrical punch 54 is restricted from moving downward by the protruding surface 27, so the metal is plastically deformed to bulge outward due to the pressure from the protrusion 51 and the cylindrical punch 54. In addition, the cylindrical punch 54 can move slightly horizontally, so its horizontal position can be changed to the optimal position when pressing. This is because if the cylindrical punch 54 were fixed so that it could not move horizontally, it would bend when the material flows, causing the axis and tip to be at an angle. Therefore, it is designed to move with some play so that it can follow flexibly. As a result, an effective crimped joint is formed on the outside of the cylindrical punch 54 and the outside of the protrusion 51, allowing the upper metal plate 91 and the lower metal plate 92 to be joined. In this way, crimp joints are formed on the outside of the three protrusions 51 and the outside of the three cylindrical punches 54, and the metal plate 90 can be firmly joined with a total of six crimp joints.

[0025] As shown in Figure 7, the joined metal plate 90 has shallow crimp joints 93 that are shallowly pressed outwards on the outside of the extended portions 51a of the three protrusions 51 and deep crimp joints 94 that are deeply pressed outwards on the outside of the three cylindrical punches 54, resulting in a total of six crimp joints that firmly join the upper metal plate 91 and the lower metal plate 92. The shallow crimp joints 93 and deep crimp joints 94 are formed alternately in the circumferential direction. Furthermore, since the shallow crimp joints 93 and deep crimp joints 94 are provided at positions opposite to the center of the crimp joint, the strength balance of the crimp joint is good, and the joint can be joined without bias in direction. In addition, since these crimp joints are provided in six directions, each metal plate 90 cannot be rotated relative to the others, and it has strong resistance to horizontal rotation. Furthermore, by providing protruding surfaces 27 at positions opposite to the cylindrical punches 54 and protrusions 51, the metal can be made to protrude significantly outwards, enabling a stronger joint. When the die 10 and punch plate 50 are closed, if the distance between the cylindrical punch 54 and the protruding surface 27 is set to less than half the thickness of the multiple metal plates to be joined, the metal can be effectively extended outwards from the cylindrical punch 54, the protruding part 51 and the protruding surface 27, and a strong bond can be achieved.

[0026] (Second Embodiment) Figure 9 shows a die 10 having a recess of a metal plate crimping mold 100 according to the second embodiment, and Figure 10 shows a plan view of a protrusion formed on the punch plate 50.

[0027] Similar to the first embodiment, the die 10 has a die recess 20 formed on its upper surface. The bottom surface 26 of the die recess 20 has a protruding surface 27 that projects upward. Similar to the first embodiment, the protruding surface 27 is located in the center, spaced apart from the inner wall surface 25. In this second embodiment, as shown in Figure 9, a burring punch 28, whose tip is bullet-shaped or tapered, is provided to protrude approximately in the center of the protruding surface 27 in order to create a burring hole 95 in the crimping joint at the same time as pressing. On the other hand, the punch plate 50 is provided with a burring punch hole 58 into which the burring punch 28 is inserted during pressing. The other configurations are the same as in the first embodiment, so their description is omitted.

[0028] When the stacked metal plates 90 are pressed with the crimping die 100 manufactured as described above, a burring hole 95 can be provided in the center of the crimped joint, which is formed in substantially the same manner as in the first embodiment, as shown in Figure 11.

[0029] By forming a crimped joint using the metal plate crimping die 100 according to the second embodiment, a burring hole 95 can be provided approximately in the center of the crimped joint at the same time as the crimping joint is performed. In this case, burring holes 95 are formed in all of the stacked metal plates, and by fastening with screws having a diameter slightly larger than the burring holes 95, all of the burring holes 95 in the stacked metal plates can be screwed in, resulting in a strong fixation. The stacked metal plates fixed with such screws can be made into a joined metal plate that has high strength in both the tensile properties and peel strength properties of each metal plate.

[0030] It should be noted that the present invention is not limited in any way to the embodiments described above, and can be implemented in various forms as long as they fall within the technical scope of the present invention. [Industrial applicability]

[0031] As shown in the embodiments described above, this can be used industrially as a mold for crimping and joining metal plates. [Explanation of symbols]

[0032] 10…Die, 20…Die recess, 21…Corner curved wall surface, 21a…Wall surface with high curvature, 21b…Wall surface with low curvature, 22…Intermediate curved wall surface, 25…Inner wall surface, 26…Bottom surface, 27…Protruding surface, 50…Punch plate, 51…Protruding part, 51a…Extended part, 52…Protruding part, 54…Cylindrical punch, 55…Through hole, 90…Metal plate, 91…Upper metal plate, 92…Lower metal plate, 93…Shallow crimp joint, 94…Deep crimp joint, 100…Die for crimp joint

Claims

1. In a mold for joining multiple metal plates by plastically deforming them through pressing, the metal plates are stacked and arranged between a die having a recess and a punch plate having a convex portion. The inner wall surface of the recess has three corner curved wall surfaces provided on a convex curved surface radiating in three directions from the center, and an intermediate curved wall surface formed between each corner curved wall surface and the adjacent corner curved wall surface. The bottom surface of the recess has an upwardly projecting surface that is made of a surface that is spaced apart from the inner wall surface. The aforementioned protrusion consists of a projection having a three-pronged surface extending in three directions, and a cylindrical punch positioned between each of the aforementioned projections. The crimping die is characterized in that the cylindrical punch is positioned to press the metal plate on the inside of the intermediate curved wall surface.

2. A burring punch, whose tip is shaped like a bullet or tapered, is provided approximately in the center of the aforementioned protruding surface in order to create a burring hole. The joining mold according to claim 1, characterized in that the punch plate is provided with a burring punch hole into which the burring punch is inserted during stamping.

3. The crimping die according to claim 1 or 2, characterized in that the protruding surface has a shape that is offset inward from the inner wall surface of the recess.

4. The crimping die according to claim 1 or 2, characterized in that the cylindrical punch has a protruding length longer than the protruding portion.

5. The crimping die according to claim 4, characterized in that the cylindrical punch is positioned in a through hole formed in the punch plate having a diameter larger than the diameter of the cylindrical punch.

6. The crimping die according to claim 5, characterized in that when the die and the punch plate are closed, the distance between the cylindrical punch and the protruding surface is less than or equal to half the thickness of the multiple metal plates to be joined.

7. In a metal plate joined by a crimping die according to claim 1 or 2, The crimped joint is characterized by comprising three deeply pressed crimped joints and three shallow crimped joints formed between these deep crimped joints, forming a joined metal plate.

8. In a metal plate joined by a crimping die according to claim 2, The crimped joint is characterized by having three deeply pressed crimped joints, three shallow crimped joints formed between these deep crimped joints, and a burring hole formed in the center thereof, forming a joined metal plate.

9. The joined metal plate according to claim 8, characterized in that a screw is fastened in the burring hole.

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