JP5213028B2 - Method for caulking and joining metal plates - Google Patents

Description

  The present invention relates to a caulking joining method for metal plates, and more particularly to a caulking joining method capable of increasing the joining strength simply and at low cost.

  As a method for fixing and joining a plurality of stacked metal plates, a method using a fastener represented by a bolt or a rivet is generally used. However, in the method using a fastener, a pilot hole is required as a pretreatment for inserting the fastener, and the cost is increased because a fastener is required. Furthermore, since the head of the fastener protrudes from the surface of the metal plate, the appearance may be impaired in handling or appearance. As other methods, a welding method such as spot welding or caulking joining may be employed.

In the spot welding method, it is difficult to join materials with different thicknesses or different materials as compared with the caulking joining method, and further, since the thermal influence on the material occurs, post-repair is necessary for the plated material. In addition, the spot welding method involves scattering and fume at the time of joining, which may deteriorate the working environment. However, since the caulking joining can be performed during press working, the equipment synchronism and the working environment are good. For this reason, caulking is frequently used in fields such as automobiles, home appliances, and houses. However, the caulking joining method has a problem that the joining strength is lower than a method using a fastener or a spot welding method.
Therefore, in Patent Document 1, when a concave mold is formed toward the back side by using a punch and a die and crimping is performed, the pin welded to the tip of the punch is substantially coincident with the surface of the metal surface. It has been proposed to plastically deform a part of a plurality of stacked metal plates into a bottomed cylindrical shape having a pin as a core by pressing the metal plate with a plurality of metal plates to a position.

Also, in the caulking joining method, when the punch is pushed into the metal plate to form a concave mold, if the punch tip or the pedestal of the die is flat, a large pressing force is required to plastically flow the metal plate material, and productivity is increased. May decrease.
Therefore, in Patent Document 2, a die having a conical surface convex toward the metal plate at the tip of the punch and a conical surface convex toward the metal plate at the tip of the die is used. Caulking and joining.
JP 2006-875 JP 2003-33829 A

The techniques proposed in Patent Documents 1 and 2 are effective as means for caulking and joining metal plates.
However, it is not sufficient for the problem of increasing the bonding strength. The inventors of the present invention have found that the caulking joining strength is greatly affected by the side wall thickness S1 of the upper metal plate and the interlock amount C1 in the caulking joining as shown in the cross section shown in FIG. However, in a general caulking joining method, S1 cannot be increased and the joining strength cannot be increased. Even if the method of Patent Document 2 is used, S1 cannot be increased.

As described above, since the high-strength bonding cannot be performed by the caulking bonding, when a high bonding strength is required, it is necessary to increase the number of bonding portions, resulting in an increase in cost.
The present invention has been devised to solve such problems, and it is an object of the present invention to provide a caulking joining method capable of improving the joining strength by increasing the side wall thickness S1 and the interlock amount C1. And

  In order to achieve the object of the caulking and joining method of the metal plate of the present invention, a plurality of metal plates are arranged on the movable blade divided and arranged on the outer periphery of the fixed anvil, and in the first step, the metal plate The upper and lower metal plates are mechanically deformed by pressing the cylindrical punches locally from above to plastically deform the upper metal plates and by individually letting out the movable blades in the outer circumferential direction. Then, in the second step, the cylindrical punch is replaced with a conical punch having a diameter larger than that of the cylindrical punch and having a convex tip, and the conical punch is replaced with the cylindrical punch. It is characterized in that the material around the cylindrical depression is plastically flowed by being pushed into a cylindrical depression formed in the metal plate by pushing.

According to the present invention, the side wall thickness S1 and the interlock amount C1 can be increased in the concave mold portion formed by caulking. For this reason, it is possible to perform caulking bonding with high bonding strength.
By enabling caulking bonding with high bonding strength, the number of bonding points can be reduced, resulting in a reduction in cost.

As described above, the caulking joining method is not sufficient when a high joining strength is to be obtained stably as compared with the spot welding method. This is because when the caulking is performed, the thickness of the side wall and the amount of interlock in the concave portion formed for the bonding are difficult to increase.
The inventors of the present invention have intensively studied about means for increasing the thickness of the side wall and the amount of interlock. As a result, it is effective to push the bottomed cylindrical concave portion in the circumferential direction by pushing the conical punch again into the bottomed cylindrical concave portion for joining formed by pushing the cylindrical punch. I found.
Details will be described below.

  First, the formation of the bottomed cylindrical concave portion for joining is exactly the same as usual. That is, as shown in FIG. 2A, after the two metal plates 1 and 2 are stacked on the blade 6 and placed, the metal plates 1 and 2 are sandwiched between the blade 6 by the stripper 4 and fixed and set. . Thereafter, as shown in FIG. 2B, the metal plates 1 and 2 set by the cylindrical punch 3 are pressed and plastically deformed to join the metal plates 1 and 2 together. At this time, since the material protrudes in the radial direction from the anvil 5, the material moves outward in the radial direction together with the blade 6 movably attached in the radial direction. Then, the bottomed cylindrical concave portion is formed and the metal plates 1 and 2 are joined. Thereafter, as shown in FIG. 3, the cylindrical punch 3 is pulled out, and the normal caulking joining is finished.

The next step is the greatest feature of the present invention.
As shown in FIG. 4A, a conical punch 7 is used instead of the cylindrical punch 3 used for caulking. The conical punch 7 spreads the bottomed cylindrical concave portion formed by the cylindrical punch 3 in the circumferential direction, and has a conical shape having a diameter larger than that of the cylindrical punch 3 and having a convex tip. Is used. It is preferable to use a cone having a central angle θ of about 120 to 160 degrees.

  The tip of the conical punch 7 is set so as to coincide with the center of the bottomed cylindrical concave portion, and the metal plates 1 and 2 are pressed. At this time, the material around the concave part upper part of the metal plate 1 is pressed against the concave part side wall part to cause plastic flow and increase the thickness of the concave part side wall part. Furthermore, since the side wall portion is compressed from above, the interlock portion further spreads outward and the blade 6 moves further outward, so that the interlock portion can also be increased in thickness (see FIG. 4B). .

  When the central angle θ of the conical punch 7 is less than 120 degrees, the tip of the conical punch first comes into contact with the bottom of the concave portion, and the side wall portion of the concave portion cannot be increased. Conversely, when the angle θ increases to exceed 160 degrees, the entire bottomed cylindrical concave portion is pressed including its periphery, and the side wall portion of the concave portion cannot be increased. . Therefore, although depending on the thickness of the plate to be joined and the diameter of the concave portion to be formed, the range of the punch 7 center angle θ is preferably 120 to 160 degrees from the viewpoint of efficient thickening.

Two sheets of 1.6-mm-thick Zn—Al—Mg hot-dip hot-dip steel sheets having the chemical components and mechanical properties shown in Table 1 were stacked as test materials, and first, ordinary caulking was performed in the manner shown in FIGS. Bonding was performed. At this time, a cylindrical punch having a diameter of 4.5 mm and a punch of R0.2 was used, and an anvil having a diameter of 5 mm was used. The gap jm between the blade upper part and the anvil was 1.0 mm. A cylindrical punch was pushed in by 3.3 mm.
For one of the above caulked joined bodies, the interlock amount C1 and the side wall thickness S1 of the joint section were measured.

Next, another one of the above caulked joined bodies was further pressed with a punch. At this time, instead of the cylindrical punch, a conical punch having a diameter of 12 mm and a central angle indicated by θ of 140 ° in FIG.
In the same manner as described above, the interlock amount C1 and the side wall thickness S1 of the joint section were measured.
The measurement results are shown in Table 2.

A cross tension test was performed on the above-described two types of caulked joints, that is, the one in which only the cylindrical punch was pressed and the one in which the conical punch was pressed after the cylindrical punch was pressed. The cross tension test was performed according to JIS Z3137.
The results are also shown in Table 2.
As is apparent from the results shown in Table 2, the side wall thickness and the interlock portion thickness are increased by simply pushing the cylindrical punch, and further pushing the conical punch. It is increased by 50% compared to the case where the cylindrical punch is pushed. It can be seen that the two-stage pressing method using a conical punch is effective.

Side wall thickness S1 and interlock amount C1 in the caulking joint section Drawing explaining the 1st process of the caulking joining method of the present invention Drawing explaining the caulking and joining state after the first step Drawing explaining the 2nd process of the caulking joining method of the present invention

Explanation of symbols

1: Metal plate (upper plate) 2: Metal plate (lower plate) 3: Cylindrical punch
4: Stripper 5: Anvil 6: Blade 7: Conical punch
C1: Interlock amount S1: Side wall thickness
jm: Clearance between blade upper part and anvil

Claims (1)

  A plurality of metal plates are placed on a movable blade divided and arranged on the outer periphery of the fixed anvil, and in the first step, a cylindrical punch is locally pushed into the metal plate from above to plasticize the upper metal plate. While deforming, each of the movable blades individually escape in the outer circumferential direction to plastically deform the lower metal plate and mechanically join the upper and lower metal plates, and then in the second step, the cylindrical punch, The cylindrical punch is replaced with a conical punch having a diameter larger than that of the cylindrical punch and having a convex tip, and the conical punch is pushed into a cylindrical recess formed in a metal plate by pushing the cylindrical punch. A method for caulking and joining metal plates, characterized in that the material around the depression is plastically flowed.

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