Crimping method and crimping device

Abstract

To provide a technique that is able to restrict a decrease in a surface pressure between two or more members after caulking and joining, while restricting an increase in manufacturing cost.SOLUTION: A caulking method for caulking and joining two or more members by using a punch having a projecting portion and a dice having a recessed portion, includes: a cooling step of cooling the projecting portion of the punch to a predetermined first temperature; a joining step of deforming the two or more members into a shape along the recessed portion, by arranging the two or more members one on another on the recessed portion of the dice and pushing the projecting portion of the punch, cooled in the cooling step, into the recessed portion via the two or more members and caulking and joining the two or more members; a maintaining step of maintaining a state in which the projecting portion is disposed in the recessed portion, for a predetermined first time after the joining step; and a take-out step of taking out the two or more members from the dice after a lapse of a predetermined second time from removal of the projecting portion from inside the recessed portion after the maintaining step.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a crimping method and a crimping joining device. [Background technology]

[0002] Patent Document 1 discloses a technique for crimping and joining two or more components using a punch, a pin abutted against the tip of the punch, and a die with a recess. In this technique, the pin is used to press two or more components placed on the die toward the recess. As a result, the two or more components are deformed by the pressure of the pin to fit the shape of the recess, and are joined. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-875 A Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional technology, the pin is left in the recess in order to suppress a decrease in the surface pressure between two or more components after crimping. This requires a pin every time crimping is performed, and the manufacturing cost increases by the amount of the pin. Therefore, there is a need for a technology that can suppress a decrease in the surface pressure between two or more components after crimping while suppressing an increase in manufacturing costs. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms. (1) According to one embodiment of the present disclosure, there is provided a crimping method, which uses a punch having a convex portion and a die having a concave portion to crimp and join two or more members, the crimping method including a cooling step of cooling the convex portion of the punch until it reaches a predetermined first temperature, a joining step of overlapping and arranging the two or more members on the concave portion of the die and pressing the convex portion of the punch cooled in the cooling step into the concave portion via the two or more members to deform the two or more members into a shape that conforms to the concave portion, thereby crimping and joining the two or more members, a maintaining step of maintaining the state in which the convex portion is arranged in the concave portion for a predetermined first time after the joining step, and a maintaining step of maintaining the state in which the convex portion is arranged in the concave portion after the maintaining step. and a removal process of removing the two or more components from the die after a predetermined second time has elapsed after the convex portion has been removed from the concave portion, wherein the two or more components include a first component that is placed on the punch side in the joining process and contacts the convex portion, and a second component that is placed on the die side in the joining process and contacts the die, wherein the first time is the time until the temperature of the first component drops to a predetermined second temperature, the first temperature being lower than or equal to the second temperature, and the second temperature being lower than or equal to -90°C, and the second temperature being set higher as the thermal expansion coefficient of the first component increases. (2) According to another aspect of the present disclosure, there is provided a crimping and joining device for crimping two or more members, the crimping and joining device including a punch having a convex portion, a die having a concave portion, and a control device, the control device pressing the convex portion of the punch, which has been cooled to a predetermined first temperature, into the concave portion via the two or more members arranged in an overlapping manner on the concave portion of the die, thereby deforming the two or more members into a shape that conforms to the concave portion, crimping and joining the two or more members, maintaining the state in which the convex portion is arranged within the concave portion for a predetermined first time, and after the convex portion is removed from within the concave portion, the control device pressing the convex portion of the punch having a convex portion into the concave portion of the die, thereby deforming the two or more members into a shape that conforms to the concave portion, and crimping and joining the two or more members, maintaining the state in which the convex portion is arranged within the concave portion for a predetermined first time, After a second time period has elapsed, the two or more components are removed from the die, the two or more components including a first component that is arranged on the punch side in the crimping joining and contacts the convex portion, and a second component that is arranged on the die side in the crimping joining and contacts the die, the first time period is a time period until a temperature of the first component falls to a predetermined second temperature, the first temperature is equal to or lower than the second temperature, and the second temperature is equal to or lower than -90°C, and the control device sets the second temperature higher as the thermal expansion coefficient of the first component increases.

[0006] (1) According to one embodiment of the present disclosure, a crimping method is provided. The crimping method for crimping two or more members using a punch having a convex portion and a die having a concave portion includes a cooling step of cooling the convex portion of the punch to a predetermined first temperature, a joining step of placing the two or more members on top of each other on the concave portion of the die, and pressing the convex portion of the punch cooled in the cooling step into the concave portion via the two or more members to deform the two or more members into a shape that conforms to the concave portion and crimp the two or more members, a maintaining step of maintaining the state in which the convex portion is placed in the concave portion for a predetermined first time after the joining step, and a removal step of removing the two or more members from the die after a predetermined second time has elapsed after the maintaining step. According to this embodiment, the temperature of the member in contact with the convex portion is reduced by performing the maintaining step after performing the joining step using the cooled convex portion. Then, the convex portion is removed from the concave portion, and a second time is allowed to elapse, thereby causing the member that was in contact with the convex portion to thermally expand and increasing the surface pressure. This makes it possible to suppress a decrease in the surface pressure between the two or more members after crimping. Therefore, parts such as pins are not left on the two or more members after crimping, and it is possible to suppress a decrease in the surface pressure between the two or more members after crimping. (2) In the above embodiment, the two or more members may include a first member disposed on the punch side in the joining step and in contact with the protruding portion, and a second member disposed on the die side in the joining step and in contact with the die, and the first time may be a time required for the temperature of the first member to drop to a predetermined second temperature. According to this embodiment, in the maintaining step, the protruding portion of the punch is brought into contact with the first member, thereby cooling the first member until the temperature of the first member drops to the predetermined second temperature. (3) In the above embodiment, the second time may be a time until the temperature of the first member reaches a predetermined third temperature that is at least higher than the second temperature after the convex portion is removed from the concave portion. According to this embodiment, the temperature of the first member that is cooled by contact with the convex portion of the punch in the maintaining step can be increased to a temperature equal to or higher than the predetermined third temperature. This makes it possible to more reliably thermally expand the first member. Therefore, it is possible to further suppress a decrease in the surface pressure between two or more members after crimping. (4) In the above embodiment, in the maintaining step, the convex portion may be disposed in the recess without applying a load to the two or more members in a direction toward the recess. According to this embodiment, in the maintaining step, a decrease in the surface pressure between the two or more members after crimping can be suppressed without applying a load to the two or more members. (5) In the above embodiment, in the maintaining step, the protrusion may be disposed in the recess with a load being applied to the two or more members. According to this embodiment, in the maintaining step, the protrusion of the punch can be disposed in the recess of the die with a load being applied to the two or more members. (6) According to another embodiment of the present disclosure, a crimping and joining device is provided. The crimping and joining device for crimping two or more members includes a punch having a convex portion, a die having a concave portion, and a control device, and the control device presses the convex portion of the punch, which has been cooled to a predetermined first temperature, into the concave portion via the two or more members arranged in a superposed manner on the concave portion of the die, thereby deforming the two or more members into a shape that conforms to the concave portion and crimping and joining them, maintains the state in which the convex portion is arranged in the concave portion for a predetermined first time, and removes the two or more members from the die after a predetermined second time has elapsed since the convex portion was removed from the concave portion. According to this embodiment, after performing the joining process using the cooled convex portion, a maintaining process is performed to reduce the temperature of the member in contact with the convex portion. Then, by allowing the second time to elapse after removing the convex portion from the concave portion, the member in contact with the convex portion is thermally expanded to increase the surface pressure. This makes it possible to suppress a decrease in the surface pressure between two or more members after crimping. The present disclosure can be realized in various forms other than the above-described crimping method, for example, in the form of a crimping device, a control method for a crimping device, a control method for a crimping method, a computer program for realizing the control method, a non-transitory recording medium on which the computer program is recorded, etc. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram showing a schematic configuration of a crimping joining system in the present embodiment. [Diagram 2] 4 is a flowchart showing a crimping method according to the present embodiment. [Diagram 3] 5A to 5C are diagrams for explaining each step of a crimping method. [Figure 4] 13 is a diagram showing the surface pressure between members when crimping is performed without thermally expanding the first member. FIG. [Diagram 5] 6 is a diagram showing a surface pressure between members when crimping is performed according to the present embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A. Embodiment: FIG. 1 is a schematic diagram showing a schematic configuration of a crimping system 1 in this embodiment. The crimping method of this embodiment is performed by the crimping system 1. In FIG. 1, components of the crimping system 1 are shown in a schematic manner. In the following description, the gravity direction side is the lower side, and the opposite side to the gravity direction is the upper side. The crimping system 1 performs crimping by deforming two or more overlapping members using a punch P having a convex portion P1 and a die D having a concave portion D1. In this embodiment, the second member W2 is disposed on the concave portion D1 of the die D so as to contact the die D, and the first member W1 is disposed on the second member W2, and the first member W1 and the second member W2 are crimped together. The first member W1 and the second member W2 are, for example, one end and the other end, which are both ends of a spiral coil constituting a motor. The crimping method of this embodiment is so-called clinching. The crimping method of this embodiment may be performed on three or more members. In this case, one or more members are disposed between the first member W1 and the second member W2.

[0009] The first member W1 and the second member W2 are each formed of a metal such as copper, iron, aluminum, or an alloy of these metals. In this embodiment, the first member W1 and the second member W2 are each a copper plate. The first member W1 and the second member W2 may be formed of different materials. In the following, when there is no need to distinguish between the first member W1 and the second member W2, they are simply called members W1 and W2. The thickness L1 of the first member W1 and the thickness L2 of the second member W2 are each a thickness that allows crimping jointing to be performed using a punch P and a die D. The thickness L1 of the first member W1 and the thickness L2 of the second member W2 are selected, for example, according to the hardness (hardness expressed by Brinell hardness or the like) of the first member W1 and the second member W2. In this embodiment, the thickness L1 of the first member W1 and the thickness L2 of the second member W2 are each 0.6 mm.

[0010] The crimping joining system 1 includes a cooling device 2 for cooling the punch P, a crimping joining device 5, and a control device 7.

[0011] The cooling device 2 includes a cooling tank 22 that stores liquid nitrogen 25. The cooling tank 22 has an opening at the top that allows the punch P to be immersed in the liquid nitrogen 25. By immersing the punch P in the liquid nitrogen 25, the punch P is cooled to a desired temperature.

[0012] The crimping joining device 5 includes a punch P, a die D, a lifting mechanism 51, and a push-out mechanism 52. The punch P presses the members W1 and W2 toward the recessed portion D1 of the die D with a predetermined load N. The punch P presses the members W1 and W2 from the first member W1 side. The first member W1 is disposed on the punch P side and contacts the protruding portion P1 of the punch P. In the following, the surface of the first member W1 that contacts the protruding portion P1 of the punch P is referred to as the first surface W1a, and the surface opposite to the first surface W1a is referred to as the first other surface W1b. In the example shown in FIG. 1, the protruding portion P1 of the punch P is provided so as to face the lower side, which is the side where the die D and the members W1 and W2 are located. In this embodiment, the protruding portion P1 of the punch P is cylindrical, but the present disclosure is not limited thereto. The protruding portion P1 of the punch P may be, for example, in the shape of a rectangular column. The first member W1 comes into contact with the protruding portion P1 of the punch P that has been cooled by the cooling device 2, and is thereby cooled.

[0013] The lifting mechanism 51 moves the punch P in a forward direction R1 in which the punch P moves toward the first member W1, and in a backward direction R2 in which the punch P moves away from the first member W1. The operation of the lifting mechanism 51 is controlled by the control device 7.

[0014] The die D supports the members W1 and W2 to be joined by crimping. The die D has a recess D1 that can receive the members W1 and W2 that are pressed and deformed by the protrusion P1 of the punch P. The second member W2 is placed on the recess D1 of the die D, and the first member W1 is placed on the second member W2. In the following, the surface of the second member W2 that contacts the first other surface W1b of the first member W1 is referred to as the second surface W2a, and the surface that is located opposite to the second surface W2a and contacts the die D is referred to as the second other surface W2b. The recess D1 of the die D is provided on the side that contacts the second other surface W2b of the second member W2. The recess D1 fits into the protrusion P1 of the punch P via the members W1 and W2.

[0015] The push-out mechanism 52 is a member for removing the members W1 and W2, which have been pressed into the recess D1 and joined, from the die D. In this embodiment, the push-out mechanism 52 is a pipe-shaped push-out ring. FIG. 1 illustrates a portion of the push-out ring. The push-out mechanism 52 removes the members W1 and W2 from the die D by lifting the members W1 and W2 from the second other surface W2b side of the second member W2. The operation of the push-out mechanism 52 is controlled by the control device 7. However, the push-out mechanism 52 is not limited to this. The push-out mechanism 52 may be any mechanism capable of removing the members W1 and W2 from the die D, and may be composed of, for example, a piston.

[0016] The control device 7 applies a driving force to and controls each of the components of the above-described crimping and joining system 1. In Fig. 1, among the components of the crimping and joining system 1 that are electrically connected to and controlled by the control device 7, a part of the electrical connection manner is typically illustrated.

[0017] FIG. 2 is a flowchart showing the crimping method of this embodiment. FIG. 3 is a diagram for explaining each step (step S1 to step S7) of the crimping method. In this embodiment, steps S1 to S7 shown in FIG. 2 are performed to crimp and join the first member W1 and the second member W2. In addition, in FIG. 3, step numbers corresponding to each step (step S1 to step S7) of the crimping method shown in FIG. 2 are given. The crimping method shown in FIG. 2 and FIG. 3 is performed in the order of a cooling step (step S1), a joining step (step S3), a maintaining step (step S5), and a removal step (step S7). Steps S3 to S7 are performed under the control of the control device 7.

[0018] As shown in Fig. 2, first, a cooling step (step S1) is performed. The cooling step (step S1) is a step of contacting the protruding portion P1 of the punch P with the first surface W1a of the first member W1 and cooling the first member W1 until the protruding portion P1 of the punch P reaches a predetermined first temperature in order to cool the first member W1 in a maintenance step (step S5) described later. Specifically, as shown in step S1 of Fig. 3, the protruding portion P1 of the punch P is immersed in liquid nitrogen 25 through an opening provided in the upper part of the cooling tank 22, and is cooled until the first temperature.

[0019] The first temperature is the temperature of the protruding portion P1 of the punch P for suitably performing the later maintaining step (step S5). Specifically, in the later maintaining step (step S5), the protruding portion P1 of the punch P cooled to the first temperature is brought into contact with the first surface W1a of the first member W1, thereby cooling the temperature of the first member W1 to the second temperature. Therefore, the first temperature needs to be lower than the second temperature used in the later maintaining step (step S5). In addition, the first temperature is the temperature of the first member W1 after the later joining step (step S3), and is lower than the temperature of the first member W1 before the maintaining step (step S5) is performed. Furthermore, it is preferable that the first temperature is sufficiently lower than the third temperature used in the later removing step (step S7). Specifically, the first temperature is preferably -40°C or lower, more preferably -100°C or lower, and even more preferably -196°C or lower. In this embodiment, the convex portion P1 of the punch P is cooled using liquid nitrogen 25 (-196°C), so the first temperature is -196°C. The lower limit of the first temperature may be -200°C or less than -200°C. When the first temperature is less than -200°C, for example, a dilution refrigerator may be used as the cooling device 2.

[0020] As shown in FIG. 2, after the cooling step (step S1), a joining step (step S3) is performed. The joining step (step S3) is a step of joining the first member W1 and the second member W2 in an arrangement state in which the second member W2 is arranged on the recessed portion D1 of the die D and the first member W1 is arranged on the second member W2. In the joining step (step S3), in the arrangement state, the punch P is moved downward in the advancing direction R1 by the lifting mechanism 51, and the members W1 and W2 are pressed by the protruding portion P1 of the punch P with a predetermined load N in a state in which the protruding portion P1 of the punch P is in contact with the first surface W1a of the first member W1. As a result, the protruding portion P1 of the punch P is pressed into the recessed portion D1 of the die D via the members W1 and W2. In this way, as shown in FIG. 3, the first member W1 and the second member W2 are deformed into a shape that conforms to the recessed portion D1 of the die D and crimped and joined. The joining step (step S3) is completed when the protruding portion P1 of the punch P is pushed into the recessed portion D1 to a predetermined position. Hereinafter, the portion of the first member W1 and the second member W2 that is deformed into a shape that conforms to the recessed portion D1 of the die D by performing the joining step (step S3) is referred to as a joint portion 57. The joint portion 57 is a cylindrical shape with a bottom.

[0021] As shown in FIG. 2, after the joining step (step S3), a maintaining step (step S5) is performed. The maintaining step (step S5) is a step of maintaining the state in which the protruding portion P1 of the punch P is disposed in the recessed portion D1 of the die D for a predetermined first time. In the maintaining step (step S5), as shown in step S5 of FIG. 3, the state in which the protruding portion P1 of the punch P and the members W1 and W2 are fitted in the recessed portion D1 of the die D is maintained. In this embodiment, in the maintaining step (step S5), the protruding portion P1 of the punch P is disposed in the recessed portion D1 of the die D without applying a load N to the members W1 and W2 in a direction toward the recessed portion D1 side. In the maintaining step (step S5), a contact state between the protruding portion P1 of the punch P cooled to the first temperature in the cooling step (step S1) and the first surface W1a of the first member W1 is maintained. Therefore, the temperature of the first member W1 can be lowered by heat conduction due to contact.

[0022] The first time is a time for cooling the first member W1. The start point of the first time is the end point of the joining process (step S3) when the protrusion P1 is pressed into the recess D1 to a predetermined position. In this embodiment, the first time is the time from the end point of the joining process (step S3) to the time when the temperature of the first member W1 drops to the second temperature. Whether or not the temperature of the first member W1 has reached the second temperature is determined by, for example, measuring the temperature of the first surface W1a of the first member W1 with an infrared thermometer.

[0023] The second temperature is the temperature of the first member W1 for favorably thermally expanding the first member W1 in the subsequent removal step (step S7). The second temperature is preferably a temperature sufficiently lower than the third temperature used in the subsequent removal step (step S7). In this embodiment, in order to favorably thermally expand the first member W1, the temperature difference between the second temperature and the third temperature is set to 100°C or more. In addition, in the maintenance step (step S5) of this embodiment, the convex portion P1 of the punch P cooled to the first temperature in the cooling step (step S1) is brought into contact with the first member W1 and cooled until it drops to the second temperature. Therefore, the second temperature may be equal to or higher than the first temperature, and is preferably -90°C or lower, and more preferably -100°C or lower. In this embodiment, since the first temperature is set to -196°C, the second temperature is set to -190°C. This allows the temperature difference between the second temperature and the third temperature to be 100°C or more.

[0024] The second temperature may be set according to the thermal expansion coefficient of the first member W1, which varies depending on the material constituting the first member W1 and the thickness L1 of the first member W1. The smaller the thickness L1 of the first member W1, the larger the thermal expansion coefficient of the first member W1. Therefore, the higher the second temperature may be set, the higher the thermal expansion coefficient of the first member W1. In other words, the higher the thermal expansion coefficient of the first member W1, the shorter the first time may be set. Also, the lower the thermal expansion coefficient of the first member W1, the lower the second temperature may be set. In other words, the lower the thermal expansion coefficient of the first member W1, the longer the first time may be set.

[0025] As shown in FIG. 2, the removal step (step S7) is performed after the maintenance step (step S5). In this embodiment, the removal step (step S7) is started when the temperature of the first member W1 reaches the second temperature. In the removal step (step S7), the punch P is first separated from the first member W1, and the protruding portion P1 of the punch P is removed from the recessed portion D1 of the die D. Specifically, as shown in FIG. 3(3), from a state in which the protruding portion P1 of the punch P is disposed in the recessed portion D1 of the die D, the punch P is moved upward in the retreat direction R2 by the lifting mechanism 51, as shown in FIG. 3(4), to separate the punch P from the first member W1. This releases contact with the cooled punch P, and the cooling of the members W1 and W2 by the punch P is terminated. At this time, as shown in FIG. 3(4), the members W1 and W2 are fitted into the recess D1 of the die D (hereinafter, referred to as a fitted state).

[0026] Next, as shown in FIG. 3(4), the mated state is maintained for a predetermined second time period, thereby increasing the temperature of the first member W1 cooled in the maintenance step (step S5). In this embodiment, the mated members W1 and W2 are left in a room temperature environment for the second time period. In this embodiment, the room temperature is 20° C.

[0027] The second time is the time required to increase the temperature of the cooled first member W1 and thermally expand the first member W1 to make the surface pressure between the members W1, W2 at the joint 57 equal to or greater than a predetermined target value. In this embodiment, the second time is the time from when the protruding portion P1 of the punch P is removed from inside the recessed portion D1 of the die D until the temperature of the first member W1 reaches a predetermined third temperature higher than the second temperature. Whether or not the temperature of the first member W1 has reached the third temperature is determined by, for example, measuring the temperature of the first surface W1a of the first member W1 with an infrared thermometer.

[0028] The third temperature is the temperature of the first member W1 for suitably thermally expanding the first member W1. It is preferable that the third temperature has a sufficient temperature difference with respect to the second temperature. Specifically, it is preferable that the third temperature is 100°C or more higher than the second temperature. In other words, it is preferable that the temperature difference between the second temperature and the third temperature is 100°C or more. The third temperature is preferably 0°C or more, and more preferably 15°C or more. The third temperature may be set according to the thermal expansion coefficient of the first member W1, which varies depending on the material constituting the first member W1 and the thickness L1 of the first member W1. In this embodiment, the third temperature is 15°C. Therefore, in this embodiment, the second time is the time until the temperature of the first member W1 that was in contact with the convex portion P1 reaches 15°C after the convex portion P1 is removed from the recess D1.

[0029] After the second time has elapsed, the joined members W1 and W2 are removed from the die D. In this embodiment, when the temperature of the first member W1 reaches the third temperature, the members W1 and W2 are removed from the die D by the push-out mechanism 52. Specifically, in the fitted state shown in FIG. 3(4), the push-out mechanism 52 lifts the members W1 and W2 from the second other surface W2b side of the second member W2, thereby removing the members W1 and W2 from the die D. The state after the joined members W1 and W2 are removed from the die D is shown in FIG. 3(5). The crimping method of this embodiment is completed by performing each process (steps S1 to S7) up to the removal process (step S7) shown in FIG. 2.

[0030] FIG. 4 is a diagram showing the surface pressure between the members W1 and W2 at the joint 57 when the crimping is performed without thermally expanding the first member W1. The surface pressure here refers to the pressure between the members W1 and W2 generated by the first member W1 and the second member W2 contacting and pressing each other at the joint 57. FIG. 4 shows the surface pressure when the crimping is performed without performing the cooling step (step S1), the maintaining step (step S5), and the step of maintaining the fitted state for a second time in the removal step (step S7). FIG. 5 is a diagram showing the surface pressure between the members W1 and W2 at the joint 57 when the crimping is performed according to this embodiment. FIG. 4 and FIG. 5 are prediction results calculated by simulation using CAE (Computer Aided Engineering), and are schematic diagrams showing the distribution of the surface pressure of the second member W2 after the crimping is performed and the magnitude of the surface pressure. In Fig. 4 and Fig. 5, the portion where the surface pressure is generated, i.e., the portion where the first other surface W1b of the first member W1 and the second surface W2a of the second member W2 are in contact, is hatched. The hatching showing the surface pressure between the members W1 and W2 at the joint 57 is shown divided into three sections according to the magnitude of the surface pressure. The three sections are 0 to 100 MPa, 100 to 200 MPa, and 200 to 350 MPa. For ease of understanding, the first member W1 is not shown in Fig. 4 and Fig. 5.

[0031] The conditions in Fig. 4 are the same as those in Fig. 5 except for the crimping method. In Fig. 4 and Fig. 5, the part of the joint 57 that faces the tip surface Pa (Fig. 1) of the protrusion P1 of the punch P is referred to as a bottom part 57a. The part of the joint 57 other than the bottom part 57a is referred to as a side part 57b. The side part 57b is a side surface of the joint 57 that is a bottomed cylindrical shape.

[0032] As shown in FIG. 4, when the first member W1 is crimped without thermal expansion, a surface pressure of about 200 to 350 MPa is applied in a band shape along the cylindrical shape of the side portion 57b. As shown in FIG. 5, in the second member W2 of the present embodiment in which the first member W1 is thermally expanded to perform crimping, a surface pressure of about 200 to 350 MPa is also applied in a band shape along the cylindrical shape of the side portion 57b. That is, the band-shaped surface pressure of about 200 to 350 MPa applied to the side portion 57b shows a similar tendency regardless of the presence or absence of thermal expansion of the first member W1. It is considered that the band-shaped surface pressure of about 200 to 350 MPa applied to the side portion 57b is a surface pressure generated by the convex portion P1 of the punch P pressing the members W1 and W2 toward the concave portion D1 of the die D in the joining process (step S3) shown in FIG. 2.

[0033] 4 and 5, the area of ​​the side portion 57b to which a surface pressure of 0 to 200 MPa is applied is larger in FIG. 5 than in FIG. 4. Specifically, the area of ​​the side portion 57b to which a surface pressure of 0 to 200 MPa is applied in FIG. 5 is more than twice as large as that in FIG. 4. The surface pressure of about 0 to 100 MPa applied to the side portion 57b is considered to be due to the provision of a cooling step (step S1), a maintaining step (step S5), and a step of maintaining the fitted state for a second time in the removal step (step S7) when performing crimping. Therefore, when crimping is performed by thermally expanding the first member W1, the surface pressure between the members W1 and W2 can be increased compared to when crimping is performed without thermally expanding the first member W1. In other words, by crimping and joining using the crimping method of this embodiment, which utilizes the thermal expansion of the first member W1, it is possible to prevent the surface pressure between the members W1 and W2 at the joint 57 between the first member W1 and the second member W2 from becoming smaller than the desired value.

[0034] According to the above embodiment, the cooling step (step S1), the joining step (step S3), the maintaining step (step S5), and the removing step (step S7) are performed to join two or more members W1 and W2 by crimping. After the joining step (step S3) is performed using the convex portion P1 cooled in the cooling step (step S1), the maintaining step (step S5) is performed to lower the temperature of the first member W1 in contact with the convex portion P1. Then, the convex portion P1 is removed from the recess D1, and the second time is allowed to elapse, thereby thermally expanding the first member W1 in contact with the convex portion P1 and increasing the surface pressure between the members W1 and W2. This makes it possible to suppress a decrease in the surface pressure between the members W1 and W2 after the crimping. In addition, by increasing the surface pressure between the members W1 and W2, the electrical resistance of the joined members W1 and W2 can be reduced.

[0035] Furthermore, according to the above embodiment, the first member W1 is thermally expanded to suppress a decrease in the surface pressure between the members W1 and W2 after the crimping. That is, it is possible to suppress a decrease in the surface pressure between the members W1 and W2 after the crimping without leaving parts such as pins on the members W1 and W2 after the crimping. This makes it possible to suppress an increase in manufacturing costs due to the crimping.

[0036] According to the above embodiment, the second time in the removal step (step S7) is the time until the temperature of the first member W1 in contact with the protruding portion P1 of the punch P reaches a third temperature higher than the second temperature after the protruding portion P1 of the punch P is removed from the recessed portion D1 of the die D. In this case, since the third temperature is 15°C in the above embodiment, the second time is the time until the temperature of the first member W1 in contact with the protruding portion P1 of the punch P reaches at least 15°C after the protruding portion P1 of the punch P is removed from the recessed portion D1 of the die D. In this way, the temperature of the first member W1 cooled in the maintenance step (step S5) can be increased to the third temperature of 15°C or more. This allows the first member W1 to thermally expand more reliably.

[0037] Also, according to the above embodiment, the first temperature, which is the temperature of the convex portion P1 of the punch P cooled in the cooling step (step S1), is -100°C or lower. In this way, when the first member W1 is cooled by the convex portion P1 of the cooled punch P, the temperature of the first member W1 can be lowered to -100°C or lower. This makes it possible to make the temperature difference between the temperature of the first member W1 after the maintaining step (step S5) and the temperature of the first member W1 after the removing step (step S7) 100°C or higher. In other words, the third temperature can be made 100°C or higher higher than the second temperature. Therefore, the first member W1 can be thermally expanded more reliably.

[0038] Furthermore, according to the above embodiment, the convex portion P1 of the punch P is cooled using liquid nitrogen 25. At this time, the temperature of the liquid nitrogen 25 is −196° C. Therefore, when cooling the convex portion P1 of the punch P in the cooling step (step S1), the temperature of the convex portion P1 of the punch P can be easily lowered.

[0039] Also, according to the above embodiment, in the maintaining step (step S5), the protruding portion P1 of the punch P is disposed in the recessed portion D1 of the die D without applying a load N to the members W1, W2 in a direction toward the recessed portion D1. In this way, it is possible to suppress a decrease in the surface pressure between the members W1, W2 after crimping without applying the load N in the maintaining step (step S5). Note that in other embodiments, in the maintaining step (step S5), the protruding portion P1 of the punch P may be disposed in the recessed portion D1 of the die D in a state in which the load N is applied to the members W1, W2. In this way, it is possible to suppress a decrease in the surface pressure between the members W1, W2 after crimping.

[0040] B. Other embodiments: In the above embodiment, the convex portion P1 of the punch P is cooled using liquid nitrogen 25, but the present disclosure is not limited to this. The convex portion P1 of the punch P may be cooled using air, for example. When cooling the convex portion P1 of the punch P using air, a cooling device using compressed air, for example, may be used as the cooling device 2. Even in this form, the convex portion P1 of the punch P can be cooled to a predetermined first temperature. Furthermore, when compressed air is used in the cooling step (step S1), the convex portion P1 of the punch P can be cooled without requiring a refrigerant or electricity.

[0041] The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features of the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention can be appropriately replaced or combined to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0042] 1... crimping joining system, 2... cooling device, 5... crimping joining device, 7... control device, 22... cooling tank, 25... liquid nitrogen, 51... lifting mechanism, 52... extrusion mechanism, 57... joining portion, 57a... bottom portion, 57b... side portion, D... die, D1... recessed portion, L1, L2... thickness, P... punch, Pa... tip surface, P1... protruding portion, R1... forward direction, R2... backward direction, W1... first member, W1a... first surface, W1b... first other surface, W2... second member, W2a... second surface, W2b... second other surface

Claims

1. A crimping method for crimping two or more members using a punch having a convex portion and a die having a concave portion, comprising the steps of: a cooling step of cooling the protruding portion of the punch to a predetermined first temperature; a joining process in which the two or more members are placed on top of each other on the recess of the die, and the protrusion of the punch cooled in the cooling process is pressed into the recess via the two or more members, thereby deforming the two or more members into a shape that conforms to the recess, thereby crimping and joining the two or more members; a maintaining step of maintaining the state in which the protrusion is disposed in the recess for a predetermined first time period after the joining step; and a removal step of removing the two or more members from the die after a second predetermined time has elapsed after the maintaining step and after the protrusion is removed from the recess. the two or more members include a first member that is disposed on the punch side in the joining process and contacts the protruding portion, and a second member that is disposed on the die side in the joining process and contacts the die, the first time period is a time period required for the temperature of the first member to decrease to a predetermined second temperature, the first temperature is less than or equal to the second temperature; the second temperature is −90° C. or lower; The crimping method, wherein the second temperature is set higher as the thermal expansion coefficient of the first member increases.

2. The crimping method according to claim 1, A crimping method, wherein the second time is a time required for the temperature of the first member to reach a predetermined third temperature that is at least higher than the second temperature after the convex portion is removed from within the concave portion.

3. The crimping method according to claim 1 or 2, In the maintaining step, the protrusion is positioned within the recess without applying a load to the two or more members in a direction toward the recess.

4. The crimping method according to claim 1 or 2, In the maintaining step, the protrusion is disposed in the recess while a load is applied to the two or more members.

5. A crimping and joining device for crimping two or more members, A punch having a protrusion; A die having a recess; A control device, The control device includes: The protruding portion of the punch, which has been cooled to a predetermined first temperature, is pressed into the recessed portion of the die via the two or more members arranged in a superposed manner on the recessed portion of the die, thereby deforming the two or more members into a shape that conforms to the recessed portion and crimping and joining them; maintaining the protrusion disposed within the recess for a first predetermined time period; removing the two or more members from the die after a second predetermined time has elapsed since the protrusions were removed from within the recesses; The two or more members include a first member that is disposed on the punch side during crimping and contacts the protruding portion, and a second member that is disposed on the die side during crimping and contacts the die, the first time period is a time period required for the temperature of the first member to decrease to a predetermined second temperature, the first temperature is less than or equal to the second temperature; the second temperature is −90° C. or lower; The control device sets the second temperature to a higher value as the thermal expansion coefficient of the first member increases.

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