JP6156034B2 - Method for joining metal plate laminate and metal plate laminate - Google Patents

Description

  The present invention relates to a method for stacking and joining a plurality of metal plates, and a metal plate laminate obtained by the joining method.

  As a method of integrating the laminated metal plates, a method of caulking and joining by rivets, a method of forming caulking protrusions and punching holes by press working, and caulking and joining the caulking protrusions to the punching holes (see Patent Document 1) ), A method in which a dissimilar metal used in the production of clad steel is pressure-bonded at a high temperature (see Patent Document 2) is known.

  However, each of the conventional methods has problems. In the method of caulking and joining with rivets, a slight protrusion remains even if the head of the rivet is crushed, so that there is a problem of interfering with peripheral parts and a step of setting the rivet to the laminate in the production process is required.

  Further, in the method of Patent Document 1, since the bonding is performed only by fitting the protrusion having a V-shaped cross section and the punched hole, the bonding strength is insufficient, and there is a possibility that separation occurs when a load is applied to the laminate in the processing process or the conveyance process. There was a desire for improvement. In the method of Patent Document 2, since the metal plate is pressed at a high temperature, in the case of a steel plate, there has been a problem that surface decarburization and annealing occur, and the hardness of the surface and inside decreases.

  As another method of integrating the laminated metal plates, there is spot welding, but since a high current and pressure are applied during implementation, the metal structure changes due to the heat effect and the surface hardness decreases, There is also a problem that the strength of the parts is lowered. In addition, a dedicated jig for positioning a plurality of metal plates at the outer peripheral portion or the like is necessary during welding.

Japanese Patent Laid-Open No. 2003-231206 JP 2011-206918 A

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a metal plate laminate bonding method and a metal plate laminate capable of ensuring bonding strength and surface hardness without requiring additional parts. There is to do.

In order to solve the above problems, a method for joining metal plate laminates according to the present invention includes:
A dowel hole (12) is formed as a through hole at a predetermined position of one first metal plate (11) of the plurality of metal plates, and each predetermined position of the other plurality of second metal plates (21). Pressing the plurality of metal plates (11, 21) such that dowel protrusions (23) are formed on the substrate,
The dowel projection (23) of the second metal plate is fitted into the dowel hole (12) of the first metal plate, and a recess (22) formed on the surface opposite to the dowel projection. The plurality of second metal plates (21) are sequentially stacked on the first metal plate (11) so that the dowel protrusions (23) of the other second metal plates are fitted. Forming a step;
A first electrode tip (51) is brought into contact with a dowel projection (23) of the second metal plate located in the dowel hole of the first metal plate of the laminate, and the first electrode of the laminate is contacted with the first electrode tip (51). A second electrode tip (52) is brought into contact with the concave portion (22) of the second metal plate located on the outermost surface opposite to the metal plate, and applied between the first and second electrode tips. A step of energizing and spot welding in a state where pressure is applied and sandwiched;
including.

The method for joining metal plate laminates according to the present invention has the following operations and effects by adopting the above-described steps.
Since the number of metal plates is one less than the number of stacked bodies in the fitting portion to be spot welded, the energy consumption during welding can be reduced accordingly.
Since the Joule heat at the time of spot welding can be concentrated at the dowel hole / dowel protrusion fitting portion, a plurality of metal plates can be welded with a small amount of energy consumption.
Since spot welding is performed within the dowel hole / dwelling protrusion fitting portion, no welding marks remain on the outer surface, and good appearance and dimensional accuracy can be obtained.
Since there is almost no thermal influence on the outer surface, the influence on the metal structure can be reduced, and the decrease in surface hardness can be suppressed.
Prior to spot welding, the laminate is fixed or temporarily fixed by fitting dowel holes / dowel protrusions, so there is no need to position the outer periphery of multiple metal plates to be joined. There is no need to create man-hours or material costs.

  In the present invention, the first and second electrode tips include a base portion having a larger diameter than the dowel protrusion and the recess, a tip convex portion having a diameter smaller than the dowel protrusion and the recess, the base portion and the tip protrusion. The aspect having the transition portion between the two portions is advantageous in that a large current can be efficiently concentrated on the dowel protrusion / recess portion having a small area.

  In the present invention, if the end surface of the tip convex portion is a substantially flat surface, the contact area between the convex portion of each electrode chip and the surface of the dowel protrusion / recess can be secured to the maximum, and the contact portion is wasted. This is advantageous for preventing excessive heat generation and accompanying adhesion of the welding tip.

In the present invention, when the metal plate is a steel plate or a metal plate having the same electrical conductivity as the steel plate, and the thickness in the state of the laminate is 2 to 9 mm,
The value of current flowing between the electrode tips is 5.5 to 7.0 kA,
The current pulse energized between the electrode tips is 10 to 20 cycles,
The applied pressure between the electrode tips is 2.1 to 3.0 kN,
Is preferred. By carrying out the method of the present invention under such conditions, poor welding such as blowholes (cavities) and poor penetration can be avoided, and high bonding strength can be reliably obtained. Since spot welding is completed in a short time, it is possible to prevent the thermal effect on the parts in contact with the laminate and the accompanying decrease in hardness.

It is typical sectional drawing which shows the joining method of the metal plate laminated body which concerns on this invention. It is a principal part expanded sectional view which shows the spot welding process of a metal plate laminated body. It is a cross-sectional photograph which shows the spot weld part of a metal plate laminated body. It is a perspective view which shows the metal plate laminated body component which implemented the joining method which concerns on this invention. It is a graph which shows the quality of the welding in each case where the applied pressure was fixed and the current value and the number of energization cycles were changed. It is a graph which shows the quality of the welding in each case where the current value was made constant and the number of energization cycles and the applied pressure were changed. It is a graph which shows the quality of the welding in each case where the electric current value and the applied pressure were changed by making the number of energization cycles constant.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the method for joining metal plate laminates according to the present invention includes (a) a step of pressing a plurality of metal plates, and (b) fitting the press-worked metal plates to form a laminate. The step of forming is carried out as a step of (c) spot welding the fitting portion.

  First, in the step of pressing, as shown in the lower part of FIG. 1 (a), one sheet of the first metal plate 11 is punched into a predetermined part shape with a press die, and at a predetermined position with a punch 41. Dowel holes 12 are drilled. Further, the plurality of second metal plates 21 are punched into a predetermined part shape with a press die, and the dowel protrusion 23 is processed with a punch 42 at a predetermined position. The dowel protrusion 23 is formed at a depth of 25 to 75% (50% in the illustrated example) of the thickness of the metal plate 21, and a recess 22 is formed on the opposite surface of the dowel protrusion 23.

  Next, in the step of forming the laminated body, as shown in FIG. 1B, the dowel protrusion 23 of the second metal plate 21 is fitted into the dowel hole 12 of the first metal plate 11, and further The dowel protrusions 23 of the next second metal plate 21 are fitted into the recesses 22 on the opposite side of the dowel protrusions 23 of the second metal plate 21, and this operation is repeated to obtain a plurality (four in the illustrated example). The laminated body 30 in which the metal plates 11 and 21 are fitted to each other via the dowel hole 12 / the dowel protrusion 23 / the recess 22 is formed.

  Next, in the step of spot welding, as shown in FIG. 1C, the dowel protrusion 23 of the second metal plate 21 positioned in the dowel hole 12 of the first metal plate 11 of the laminate 30 1 electrode chip 51 is brought into contact, and the second electrode chip 52 is brought into contact with the recess 22 of the second metal plate 21 located on the outermost surface opposite to the first metal plate 11 of the laminate 30. When a predetermined current pulse is applied between the first and second electrode tips 51 and 52 in a state where a pressing force is applied between the first and second electrode tips 51 and 52, the first and second electrode tips 51 and 52 are applied. Resistive heat generation (Joule heat) is generated along the conductive path passing through each of the metal plates 11 and 21 located between the electrode chips 51 and 52, and the metal is heated and melted by the resistance heat generation, whereby the nugget 31 is formed. The nugget 31 is cooled and solidified to form a welded joint. It is made.

  FIG. 2 shows spot welding of a laminate formed by fitting dowel protrusions 23 of six metal plates 11 and 21 into dowel holes 12 / recesses 22. In the figure, the nugget 31 spreads along the contact surface between the upper and lower outermost metal plates 11 and 21 and the adjacent metal plates 21 and 21, and the conductive path narrows from the outermost surface toward the center. As a whole, it has a pincushion shape. In the heat affected zone 32 by solid heat conduction around the nugget 31, the contact surfaces of the metal plates 11 and 21 are solid phase welded (corona bonded).

  Here, in the joining method according to the present invention, spot welding is performed at the fitting portion of the dowel hole 12 / the dowel protrusion 23 / the recessed portion 22, so that the contact surfaces (23a, 22a) is recessed with respect to the outer surfaces 11a and 21a of the metal plates 11 and 21, and the nugget 31 as well as the heat-affected zone 32 are contained in the fitting portion, and thus do not appear on the outer surfaces 11a and 21a. The hardness of the outer surfaces 11a and 21a of the metal plates 11 and 21 does not decrease due to thermal effects. Further, since the pressing force of the electrode tips 51 and 52 does not reach the outer surfaces 11a and 21a of the metal plates 11 and 21, the outer surfaces 11a and 21a are not deformed by the pressing force.

  Next, the electrode tips 51 and 52 used in spot welding in the joining method according to the present invention have a small diameter that can enter the dowel hole 12 / recess 22 that has been press-worked as shown in FIG. 1 (c) and FIG. Tip convex portions 51a and 52a, base portions 51b and 52b having a diameter larger than that of the dowel hole 12 / concave portion 22, and transition portions 51c and 52c therebetween are formed in a tapered shape.

  A cavity (not shown) for circulating cooling water is formed in the cross section from the base portions 51b and 52b of the electrode tips 51 and 52 to the transition portions 51c and 52c. Therefore, the configuration as described above forms a cooling cavity in the cross-section while maintaining the strength as the electrode tips 51 and 52, and efficiently concentrates the current path and the applied pressure on the tip protrusions 51a and 52a. This is advantageous. In addition, as a shape of the transition parts 51c and 52c, it is suitable to set it as the cone shape shown in FIG.1 (c), or the partial spherical shape shown in FIG. The material of the electrode tip is not particularly limited, but a copper alloy having a good balance between conductivity and durability, for example, chromium copper (CrCu) is preferable.

  Next, in the same manner as shown in FIG. 2, a fitting portion formed by forming dowel protrusions / dowel holes having a diameter of 2 mm on six steel plates having a thickness of 1 mm and fitting them into an electrode chip having a tip convex portion having a diameter of 1 mm. When spot welding was used, an experiment was performed in which the welding cross section was observed by changing the value of the current applied between the electrode tips, the current supply cycle, and the pressure applied between the electrode tips. The results for each welding condition are shown in FIGS.

  FIG. 5 shows the welding cross section in each case where the welding pressure is constant (2.18 kN) and the current value (5 to 7.8 kA) and the number of energization cycles (5 to 25 times) are changed. / Indicates the result of determining a defect. In this case, under low output conditions where the current value was 5 kA or less and the energization cycle was 5 cycles or less, heat generation during welding was insufficient, and a good weld joint was not formed. Specifically, the nugget 31 shown in FIG. 2 was separated into the upper and lower sides, and it was confirmed that the intermediate portion was not sufficiently melted. On the contrary, under high output conditions where the current value is 7.5 kA or more and the energization cycle is 25 or more, blowholes remain in the center portion of the nugget, and the cross-sectional area of the welded joint decreases, resulting in a decrease in joint strength. It was confirmed.

  FIG. 6 shows each case where the current value is 6 kA at which the best result is obtained in the above experiment, and the number of energization cycles (5 to 25 times) and the applied pressure (2.18 to 3.1 kN) are changed. FIG. 7 shows the welding cross section in each case where the number of energization cycles is constant (10 times) and the current value (5 to 7.8 kA) and the applied pressure (2.18 to 3.5 kN) are changed. The result of having judged good / bad of welding is shown. In either case, when the applied pressure is too small, resistance heat generation is insufficient due to the increase in resistance at the contact surface. On the other hand, when the applied pressure is too large (3.1 kN or more), electrode welding occurs. There was a trend.

  FIG. 3 shows a cross-sectional photograph (a photograph based on FIG. 2) of a welded joint at an electric current value of 6 kA, an energization cycle number of 15 times, and a pressurizing force of 2.18 kN as an example in which good results were obtained. The pincushion-shaped nugget and the surrounding heat-affected zone can be confirmed, and white corona bond stripes can be confirmed on the joining surface of the steel plate in the heat-affected zone.

  FIG. 4 shows a decompression cam 430 of a motorcycle as a metal plate laminate part subjected to the joining method according to the present invention. The decompression cam 430 is composed of a hub 434, a cam 435 projecting on one side thereof, and a weight portion 433 projecting on the other side, and three steel plates 411, 421, 421 are arranged from the bottom in the figure. The cam 435, the hub 434, and the weight portion 433 are provided in series. The hub 434 further includes six steel plates 421, and the weight portion 433 further includes three steel plates 411, 421 in total. They are laminated, and they are joined at four joints 422 by the fitting shown in FIG. 1B and the spot welding shown in FIG. 1C.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said each embodiment, Based on the technical idea of this invention, a various deformation | transformation and change are further possible.

  For example, in FIGS. 1 and 2, the peripheral side wall of the dowel protrusion 23 / recess 22 is shown straight, but the diameter of the hole of the die (not shown) that receives the punch is made larger than the diameter of the punch, A draft of about 0 to 30 ° may be formed on the peripheral side wall of the dowel protrusion. Further, the first metal plate 11 in which the dowel holes 12 are formed may be inserted into the intermediate portion of the stacked body 30.

10, 11 1st metal plate 12 Dowel hole 20, 21 2nd metal plate 22 Recess 23 Dowel protrusion 31 Nugget 32 Heat affected zone 41, 42 Punch 51, 52 Electrode tips 51a, 52a Tip convex portion 51b, 52b Base 51c , 52c Transition part

Claims (9)

A dowel hole is formed as a through hole at a predetermined position of one of the plurality of metal plates, and a dowel protrusion is formed at each predetermined position of the other plurality of second metal plates. Pressing the plurality of metal plates; and
The dowel projection of the second metal plate is fitted into the dowel hole of the first metal plate, and the other second metal plate is formed in a recess formed on the opposite surface of the dowel projection. Forming a laminate by sequentially stacking the plurality of second metal plates on the first metal plate so that the dowel projections of
A first electrode tip is brought into contact with a dowel protrusion of the second metal plate located in the dowel hole of the first metal plate of the laminate, and the opposite side of the laminate to the first metal plate The second electrode tip is brought into contact with the concave portion of the second metal plate located on the outermost surface of the metal plate, and energized in a state of being sandwiched by applying pressure between the first and second electrode tips. A step of spot welding;
A method for joining metal plate laminates. The first and second electrode tips include a base portion having a larger diameter than the dowel projection and the recess, a tip convex portion having a diameter smaller than the dowel projection and the recess, and between the base portion and the tip convex portion. bonding method of a metal plate laminated body according to claim 1, characterized in that it comprises a transition portion. The method for joining metal plate laminates according to claim 2 , wherein an end surface of the tip convex portion is a substantially flat surface. The metal plate is a steel plate or a metal plate having the same electrical conductivity as the steel plate, has a thickness of 2 to 9 mm in the state of the laminate, and between the first and second electrode chips. The method for joining metal plate laminates according to any one of claims 1 to 3 , wherein a current value for energizing the metal plate is 5.5 to 7.0 kA. The metal plate is a steel plate or a metal plate having the same electrical conductivity as the steel plate, has a thickness of 2 to 9 mm in the state of the laminate, and between the first and second electrode chips. The method for joining metal plate laminates according to any one of claims 1 to 4 , wherein the energization cycle of the current pulse energized is 10 to 20 cycles. The metal plate is a steel plate or a metal plate having the same electrical conductivity as that of the steel plate, the thickness in the state of the laminated body is 2 to 9 mm, and the applied pressure is 2.1 to 3. bonding method of a metal plate laminated body according to any one of claim 1 to 5, characterized in that a 0KN. The said metal plate is a steel plate, The joining method of the metal plate laminated body of any one of Claims 1-6 characterized by the above-mentioned. Metal plate stack including the joining by the method according to any one of claims 1-7. Three of the plurality of metal plates, each having a dowel hole formed as a through hole at a predetermined position of one first metal plate, and a dowel protrusion formed at each predetermined position of the other plurality of second metal plates a laminate of the above metal plate, the first one dowel projections among the plurality of second metal plates to said dowel holes of the metal plate is fitted, wherein one of the second metal the stacked such that the dowel protruding opposite to the surface to recess formed in the dowel projections of the other of said second metal plate of the plate is fitted, and, with the dowel projections recessed from the outer surface dowel A metal plate laminate in which a nugget and a heat-affected zone which are spot-welded at a fitting portion between a hole and the concave portion, and the fitting portion is melted and solidified are located inside a thickness range between the outer surfaces.