Solid phase joint device and solid phase joint method

Abstract

To provide a solid phase joint device which can reduce a load applied to workpiece, and a solid phase joint method using the solid phase joint device.SOLUTION: A solid phase joint device includes a pair of pressurization shafts 11 and 12 for pressurizing first workpiece W10 and second workpiece W20 made of metal from both sides in a thickness direction, a pair of electrodes 21 and 22 which are arranged in each periphery of the pair of pressurization shafts 11 and 12, and a control device 30. The control device 30 conducts first current X1 in the pair of electrodes 21 and 22 while making a first load F1 act on each of the first workpiece W10 and the second workpiece W20 and bringing them into contact with each other by controlling the pair of pressurization shafts 11 and 12, and then conducts second current X2 larger than the first current X1 in the pair of electrodes 21 and 22 while making a second load F2 act on each of the first workpiece W10 and the second workpiece W20 by controlling the pair of pressurization shafts 11 and 12.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a solid-state bonding apparatus and a solid-state bonding method using the solid-state bonding apparatus. [Background technology]

[0002] JP 2020-11253 A (Patent Document 1) discloses resistance spot welding in which multiple metal plates are stacked in the thickness direction and joined. Resistance spot welding is a welding method in which metal plates are sandwiched between electrodes and a large current is passed through them under pressure to melt the metal. The technology of JP 2020-11253 A (Patent Document 1) includes a preliminary current application process for alloying the plating metal of the metal plating layer, and a main current application process for joining multiple metal plates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-11253 A Summary of the Invention [Problem to be solved by the invention]

[0004] JP 2020-11253 A (Patent Document 1) is a technology related to resistance spot welding, and is not related to solid-state welding. In this specification, a joining method that prevents a decrease in strength due to melting of metal by a large current by joining in a solid-phase state in a low-temperature range without melting the metal is called "solid-state joining". JP 2020-11253 A (Patent Document 1) does not anticipate joining in a low-temperature range such as solid-state joining.

[0005] Here, since solid-state welding is a low-temperature process, the harder the metal workpiece is, the greater the load applied to the workpiece becomes, which in turn requires a larger device to improve durability.

[0006] An object of the present disclosure is to provide a solid-state welding apparatus capable of reducing the load applied to workpieces and a solid-state welding method using the solid-state welding apparatus. [Means for solving the problem]

[0007] A solid-state joining apparatus according to one aspect of the present disclosure includes a pair of pressure shafts for pressing a first workpiece and a second workpiece made of metal from both sides in a thickness direction, a pair of electrodes respectively arranged around the pair of pressure shafts, and a control device. The control device controls the pair of pressure shafts to apply a first load to each of the first workpiece and the second workpiece to bring them into contact with each other, while passing a first current through the pair of electrodes, and then controls the pair of pressure shafts to apply a second load to each of the first workpiece and the second workpiece, while passing a second current larger than the first current through the pair of electrodes.

[0008] A solid-state welding method according to one aspect of the present disclosure relates to a solid-state welding method using a solid-state welding apparatus including a pair of pressure shafts for pressing a first workpiece and a second workpiece made of metal from both sides in a thickness direction, a pair of electrodes respectively arranged around the pair of pressure shafts, and a control device, in which the control device executes the steps of: controlling the pair of pressure shafts to apply a first load to each of the first workpiece and the second workpiece to bring them into contact with each other, while passing a first current through the pair of electrodes; and then controlling the pair of pressure shafts to apply a second load to each of the first workpiece and the second workpiece to pass a second current larger than the first current through the pair of electrodes. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a solid-state welding apparatus capable of reducing the load applied to the workpieces by passing a first current, and a solid-state welding method using the solid-state welding apparatus. [Brief description of the drawings]

[0010] [Figure 1] 4A to 4C are diagrams illustrating a process of passing a first current in the solid-state joining apparatus according to the embodiment of the present disclosure. [Diagram 2] FIG. 13 is a diagram illustrating a second current passing step in the solid-state joining apparatus according to the embodiment of the present disclosure. [Diagram 3] FIG. 13 is a graph showing the change in current with respect to time and the change in load with respect to time. [Figure 4] FIG. 13 is a graph showing the change in current with respect to time and the change in load with respect to time. [Diagram 5] 4 is a flowchart showing the control contents executed by the control device. [Figure 6] FIG. 11 is a diagram showing changes in current and load with time when electricity is constantly applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0012] The solid-state joining apparatus 1 according to an embodiment of the present disclosure first passes a first current X1 and then passes a second current X2. Fig. 1 is a diagram illustrating a schematic diagram of a current passing process of the first current X1 in the solid-state joining apparatus 1 according to an embodiment of the present disclosure. The solid-state joining apparatus 1 is an apparatus that passes current through multiple workpieces W10, W20 stacked on top of each other to form softened regions at the interfaces of the multiple workpieces W10, W20, and plastically deforms the softened regions to join the multiple workpieces W10, W20 in a solid state without melting them.

[0013] The multiple workpieces W10, W20 include a first workpiece W10 and a second workpiece W20. Each of the workpieces W10, W20 is made of a metal such as iron or aluminum. Each of the workpieces W10, W20 is formed, for example, in a flat plate shape.

[0014] As shown in FIG. 1, the solid-state bonding apparatus 1 includes a pair of pressure shafts 11 and 12, a pair of electrodes 21 and 22, a control device 30, and a sensor 40.

[0015] The pair of pressure applying shafts 11, 12 can apply pressure to the first workpiece W10 and the second workpiece W20 from both sides in the thickness direction of the stacked plate-like workpieces. The pair of pressure applying shafts 11, 12 are driven by a drive source (such as a servo press machine) (not shown). The pair of pressure applying shafts 11, 12 has a first pressure applying shaft 11 and a second pressure applying shaft 12.

[0016] The first pressure shaft 11 has a shape that extends long in one direction (the direction of the arrow F1 in FIG. 1). The first pressure shaft 11 can press the first workpiece W10 so that the first workpiece W10 is plastically deformed. Specifically, the first pressure shaft 11 can press the first workpiece W10 so that a protrusion W11 is formed on the first workpiece W10. The first pressure shaft 11 is made of, for example, tungsten carbide. In this embodiment, the first pressure shaft 11 is formed in a cylindrical shape. The first pressure shaft 11 has a pressing surface 11a that presses the first workpiece W10. The pressing surface 11a is an end surface of the first pressure shaft 11. The pressing surface 11a is formed in a circular shape.

[0017] The second pressure applying shaft 12 has the same configuration as the first pressure applying shaft 11. The second pressure applying shaft 12 is disposed in such a manner that the central axis of the second pressure applying shaft 12 is located on an extension of the central axis of the first pressure applying shaft 11, and the pressing surface 12a of the second pressure applying shaft 12 faces the pressing surface 11a of the first pressure applying shaft 11. The first pressure applying shaft 11 and the second pressure applying shaft 12 may have a shape other than a cylindrical shape.

[0018] The sensor 40 is provided, for example, on the first pressure applying shaft 11. In this embodiment, a load cell is used as the sensor 40. Note that the location where the sensor 40 is installed is not limited to the first pressure applying shaft 11.

[0019] The pair of electrodes 21, 22 can pass electricity through the first workpiece W10 and the second workpiece W20 while in contact with the first workpiece W10 and the second workpiece W20. A voltage and a current are supplied to the pair of electrodes 21, 22 from a power supply unit (not shown). The pair of electrodes 21, 22 includes a first electrode 21 and a second electrode 22.

[0020] The first electrode 21 can contact a portion of the first workpiece W10 surrounding a portion of the first workpiece W10 that is pressed by the first pressure shaft 11. In this embodiment, the first electrode 21 is formed in a cylindrical shape surrounding the first pressure shaft 11. A gap is provided between the inner peripheral surface of the first electrode 21 and the outer peripheral surface of the first pressure shaft 11. The first electrode 21 is made of, for example, copper. The first electrode 21 has a contact surface 21a that contacts the first workpiece W10. The contact surface 21a is formed in an annular shape. The shape of the contact surface 21a is not limited to an annular shape.

[0021] The second electrode 22 has the same configuration as the first electrode 21. The second electrode 22 can come into contact with a portion of the second workpiece W20 surrounding a portion pressurized by the second pressurizing shaft 12. The second electrode 22 is disposed in such a manner that the central axis of the second electrode 22 is located on an extension of the central axis of the first electrode 21, and the contact surface 22a of the second electrode 22 faces the contact surface 21a of the first electrode 21.

[0022] The control device 30 includes a CPU 31 (Central Processing Unit), memory 32 (ROM (Read Only Memory) and RAM (Random Access Memory)), and an input / output device (not shown) for inputting and outputting various signals. The CPU 31 functions as a processing circuitry that expands a program stored in the ROM into the RAM or the like and executes it. The programs stored in the ROM are programs in which the processing procedures of the control device 30 are written. The control device 30 controls each device in accordance with these programs. This control is not limited to processing by software, and can also be processed by dedicated hardware (electronic circuitry).

[0023] The control device 30 controls the pair of pressure applying shafts 11, 12 and the pair of electrodes 21, 22. Specifically, the control device 30 controls the load acting on the first workpiece W10 and the second workpiece W20 from the pair of pressure applying shafts 11, 12, the load acting on the first workpiece W10 and the second workpiece W20 from the pair of electrodes 21, 22, the voltage applied to the pair of electrodes 21, 22, and the pressing amount of the pair of pressure applying shafts 11, 12 and the pair of electrodes 21, 22. The control device 30 controls the voltage applied to the pair of electrodes 21, 22 to control the current supplied to the pair of electrodes 21, 22.

[0024] The control device 30 performs an operation to apply a first load F1 (see FIG. 1) from the pair of pressure shafts 11, 12 to the first work W10 and the second work W20 so that protrusions W11, W21 that come into contact with each other are formed on each of the first work W10 and the second work W20. At this time, the control device 30 also performs an operation to apply an adjustment load smaller than the first load F1 (for example, a load of 1 kN or less) from the pair of electrodes 21, 22 to the first work W10 and the second work W20.

[0025] Next, the control device 30 performs an operation to pass electricity through the first workpiece W10 and the second workpiece W20. Specifically, the control device 30 applies a first load F1 to the first workpiece W10 and the second workpiece W20 from the pair of pressure shafts 11 and 12, and also brings the contact surface 21a of the first electrode 21 into contact with a portion of the first workpiece W10 surrounding a portion of the first workpiece W10 that is pressurized by the first pressure shaft 11, and brings the contact surface 22a of the second electrode 22 into contact with a portion of the second workpiece W20 surrounding a portion of the second workpiece W20 that is pressurized by the second pressure shaft 12. The control device 30 controls so that a first current X1 indicated by a dashed line flows between the pair of electrodes 21 and 22 via the protrusions W11 and W21.

[0026] Each of the protrusions W11, W21 is softened by the flow of the first current X1. In this embodiment, the control device 30 applies a first load F1 to the first workpiece W10 and the second workpiece W20 while softening each of the protrusions W11, W21 by passing the first current X1. As a result, in this embodiment, the load when forming each of the protrusions W11, W21 can be reduced compared to when the protrusions are formed without passing the first current X1.

[0027] 2 is a diagram illustrating a schematic diagram of a current passing process of the second current X2 in the solid-state joining apparatus 1 according to an embodiment of the present disclosure. The control device 30 performs an operation of applying a second load F2 larger than the first load F1 to each of the protrusions W11, W21 formed on the first workpiece W10 and the second workpiece W20. At this time, the control device 30 also performs an operation of applying an adjustment load smaller than the second load F2 (for example, a load of 1 kN or less) from the pair of electrodes 21, 22 to the first workpiece W10 and the second workpiece W20.

[0028] Next, the control device 30 performs an operation to pass electricity through the first workpiece W10 and the second workpiece W20. Specifically, the control device 30 applies a second load F2 to the first workpiece W10 and the second workpiece W20 from the pair of pressure shafts 11, 12, and also performs an operation to pass electricity through the first workpiece W10 and the second workpiece W20 while bringing the contact surface 21a of the first electrode 21 into contact with a portion of the first workpiece W10 surrounding a portion of the first workpiece W10 that is pressurized by the first pressure shaft 11 and bringing the contact surface 22a of the second electrode 22 into contact with a portion of the second workpiece W20 surrounding a portion of the second workpiece W20 that is pressurized by the second pressure shaft 12. The control device 30 controls so that a second current X2 indicated by a dashed line flows between the pair of electrodes 21, 22 via the protrusions W11, W21.

[0029] The second current X2 is a current larger than the first current X1. The second current X2 causes each of the protrusions W11, W21 to be softened further than in the state shown in FIG. 1. In this embodiment, the control device 30 applies a second load F2 to the first workpiece W10 and the second workpiece W20 while softening each of the protrusions W11, W21 by passing the second current X2. As a result, in this embodiment, the first workpiece W10 and the second workpiece W20 can be joined at the positions of each of the protrusions W11, W21.

[0030] Fig. 3 is a diagram showing the change in current over time and the change in load over time. Fig. 3(A) is a diagram showing the change in load over time when the first current X1 is not passed when the protrusions are formed. Fig. 3(B) is a diagram showing the change in current over time when the first current X1 is not passed when the protrusions are formed. Fig. 3(C) is a diagram showing the change in load over time when the first current X1 is passed when the protrusions are formed. Fig. 3(D) is a diagram showing the change in current over time when the first current X1 is passed when the protrusions are formed.

[0031] As shown in Figures 3(A) and (B), when the first current X1 is not passed during the formation of the protrusion, a load of F1' [kN] is required as the load during the formation of the protrusion. In contrast, as shown in Figures 3(C) and (D), when the first current X1 is passed during the formation of the protrusion, the protrusion can be formed with a load of F1 [kN], which is smaller than F1' [kN], as the load during the formation of the protrusion. In this way, the solid-state bonding apparatus 1 of this embodiment can reduce the load during the formation of the protrusion by passing the first current X1 during the formation of the protrusion.

[0032] As shown in Figures 3(A) and (B), if the first current X1 is not passed when the protrusion is formed, a load of F2' [kN] is required as the load during joining. In contrast, as shown in Figures 3(C) and (D), if the first current X1 is passed when the protrusion is formed, the first workpiece W10 and the second workpiece W20 can be joined with a load of F2 [kN], which is smaller than F2' [kN], as the load during joining. In this way, the solid-state joining apparatus 1 of this embodiment can reduce the load during joining by passing the first current X1 when the protrusion is formed.

[0033] FIG. 4 is a diagram showing the change in current with time and the change in load with time. Unlike FIG. 3, FIG. 4 is a diagram showing a case where the load during joining is smaller than the load during protrusion formation. FIG. 4(A) is a diagram showing the change in load with time when the first current X1 is not passed when the protrusion is formed. FIG. 4(B) is a diagram showing the change in current with time when the first current X1 is not passed when the protrusion is formed. FIG. 4(C) is a diagram showing the change in load with time when the first current X1 is passed when the protrusion is formed. FIG. 4(D) is a diagram showing the change in current with time when the first current X1 is passed when the protrusion is formed.

[0034] As shown in Figures 4(A) and (B), when the first current X1 is not passed during the formation of the protrusion, a load of F3' [kN] is required as the load during the formation of the protrusion. In contrast, as shown in Figures 4(C) and (D), when the first current X1 is passed during the formation of the protrusion, the protrusion can be formed with a load of F3 [kN], which is smaller than F3' [kN], as the load during the formation of the protrusion. In this way, the solid-state bonding apparatus 1 of this embodiment can reduce the load during the formation of the protrusion by passing the first current X1 during the formation of the protrusion.

[0035] As shown in Figures 4(A) and (B), if the first current X1 is not passed when the protrusion is formed, a load of F4' [kN] is required as the load during joining. In contrast, as shown in Figures 4(C) and (D), if the first current X1 is passed when the protrusion is formed, the first workpiece W10 and the second workpiece W20 can be joined with a load of F4 [kN], which is smaller than F4' [kN], as the load during joining. In this way, the solid-state joining apparatus 1 of this embodiment can reduce the load during joining by passing the first current X1 when the protrusion is formed.

[0036] As shown in Figures 3 and 4, the solid-state welding apparatus 1 of this embodiment can reduce the load during welding by passing the first current X1 during protrusion formation, whether the load during welding is greater or smaller than the load during protrusion formation. Note that, as shown in Figures 3 and 4, the solid-state welding apparatus 1 of this embodiment temporarily stops the passage of current between the first current X1, which is the current for reducing the load, and the second current X2, which is the current for welding. This is to prevent each of the protrusions W11 and W21 from melting and changing in properties due to continued current passing.

[0037] Next, the processing executed by the control device 30 will be described. Fig. 5 is a flowchart showing the control contents executed by the control device 30. The processing of the flowchart in Fig. 5 is repeatedly called as a subroutine from the main routine in the control of the control device 30 and executed. First, in step S (hereinafter simply referred to as "S") 1, the control device 30 moves the pair of pressure shafts 11, 12 toward the first workpiece W10 and the second workpiece W20, respectively.

[0038] Next, the control device 30 judges whether the pair of pressure shafts 11, 12 are in contact with the first workpiece W10 and the second workpiece W20, respectively (S2). For example, the control device 30 acquires the detection value of the sensor 40, and judges that the pair of pressure shafts 11, 12 are in contact with the first workpiece W10 and the second workpiece W20 based on an increase in the detection value. The control device 30 stores the contact position as a reference position in S2. When the control device 30 judges that the pair of pressure shafts 11, 12 are not in contact with the first workpiece W10 and the second workpiece W20, respectively (NO in S2), it returns to the process of S1. When the control device 30 judges that the pair of pressure shafts 11, 12 are in contact with the first workpiece W10 and the second workpiece W20, respectively (YES in S2), it proceeds to the process of S3.

[0039] In S3, the control device 30 executes a process of pressing the pair of pressure shafts 11, 12 to the protrusion formation positions and passing a first current X1 for load reduction. Next, the control device 30 judges whether the pair of pressure shafts 11, 12 have reached the protrusion formation positions (S4). For example, the control device 30 may judge whether the pair of pressure shafts 11, 12 have moved from the contact positions stored in S2 to the protrusion formation positions where the protrusions W11, W21 are formed on the first workpiece W10 and the second workpiece W20. The control device 30 stores the protrusion formation positions as a reference position in S4. When the control device 30 judges that the pair of pressure shafts 11, 12 have not reached the protrusion formation positions (NO in S4), it returns to the process of S3.

[0040] When the control device 30 determines that the pair of pressure shafts 11, 12 have reached the protrusion formation positions (YES in S4), it proceeds to processing in S5. When the pair of pressure shafts 11, 12 have reached the protrusion formation positions, a first load F1 acts on the first workpiece W10 and the second workpiece W20. In S5, the control device 30 stops energization for a preset time and maintains pressure on the pair of pressure shafts 11, 12.

[0041] Next, the control device 30 executes a process of pressing the pair of pressure shafts 11, 12 to the joining position and passing the second current X2 for joining (S6). Next, the control device 30 judges whether or not the protrusions W11, W21 of the first work W10 and the second work W20 have been softened based on the detection value of the sensor 40 (S7). The control device 30 judges whether or not the protrusions W11, W21 have been softened, for example, based on whether or not the detection value of the sensor 40 is equal to or less than a predetermined threshold value. When the control device 30 judges that the protrusions W11, W21 have not been softened (when the detection value of the sensor 40 is greater than the threshold value), it returns to S6. When the control device 30 judges that the protrusions W11, W21 have been softened (when the detection value of the sensor 40 is equal to or less than the threshold value), it proceeds to the process of S8.

[0042] The control device 30 determines whether or not the pair of pressure shafts 11, 12 have reached the joining positions in S8. For example, the control device 30 may determine whether or not the pair of pressure shafts 11, 12 have moved from the protrusion formation positions stored in S4 to the joining positions where the first workpiece W10 and the second workpiece W20 are joined.

[0043] When the control device 30 determines that the pair of pressure shafts 11, 12 have not reached the joining position (NO in S8), the process returns to S6. When the control device 30 determines that the pair of pressure shafts 11, 12 have reached the joining position (YES in S8), the process returns to the main routine from the subroutine. When the pair of pressure shafts 11, 12 have reached the joining position, the second load F2 acts on the first workpiece W10 and the second workpiece W20.

[0044] 5, the solid-state welding apparatus 1 of this embodiment can reduce the load during protrusion formation by passing a first current X1 during protrusion formation in S3, and can also reduce the load during welding because the joints of the first workpiece W10 and the second workpiece W20 are softened by the first current X1. As a result, the solid-state welding apparatus 1 of this embodiment can improve the durability of the pair of pressurizing shafts 11, 12 and avoid an increase in size of the drive source (such as a servo press) by adding a process of passing current to soften the joints.

[0045] Next, a case where the current flow is not stopped between the time of forming the protrusion and the time of joining will be described. FIG. 6 is a diagram showing the change in current and the change in load with time when the current is constantly flowing. FIG. 6(A) is a diagram showing the change in load with time when the first current X1 is not passed when the protrusion is formed. FIG. 6(B) is a diagram showing the change in current with time when the first current X1 is not passed when the protrusion is formed. FIG. 6(C) is a diagram showing the change in load with time when the first current X1 is passed when the protrusion is formed. FIG. 6(D) is a diagram showing the change in current with time when the first current X1 is passed when the protrusion is formed.

[0046] In FIG. 6, the load increases continuously from the time of protrusion formation to the time of joining. As shown in FIGS. 6(A) and (B), if the first current X1 is not applied during the protrusion formation, a load of F5' [kN] is required as the load during joining. On the other hand, as shown in FIGS. 6(C) and (D), if the first current X1 is applied during the protrusion formation, the first workpiece W10 and the second workpiece W20 can be joined with a load of F5 [kN], which is smaller than F5' [kN], as the load during joining. In this way, the solid-state joining apparatus 1 of the present embodiment can reduce the load during joining even if the current supply is not stopped between the time of protrusion formation and the time of joining by applying the first current X1 during the protrusion formation, and can shorten the overall processing period.

[0047] In the above embodiment, the detection value of the load cell is used as the sensor 40, but the softening of each workpiece W10, W20 may be detected by a sensor other than the load cell. As such a sensor, a camera capable of photographing the contact portion between the protrusions W11, W21 may be used. In this case, the control device 30 determines whether each workpiece W10, W20 has been softened based on the brightness of the contact portion. As such a sensor, a contact or non-contact thermometer may be used. The control device 30 may determine whether each workpiece W10, W20 has been softened based on the temperature of the contact portion. Alternatively, the control device 30 may determine whether each workpiece W10, W20 has been softened based on the result of the heat amount calculation of each workpiece W10, W20 acquired in advance and the timer of the power supply.

[0048] <Summary> (1) The solid-state joining apparatus 1 of the present disclosure includes a pair of pressure shafts 11, 12 that press a first workpiece W10 and a second workpiece W20 made of metal from both sides in the thickness direction, a pair of electrodes 21, 22 that are respectively arranged around the pair of pressure shafts 11, 12, and a control device 30. The control device 30 controls the pair of pressure shafts 11, 12 to apply a first load F1 to each of the first workpiece W10 and the second workpiece W20 to bring them into contact with each other, while passing a first current X1 through the pair of electrodes 21, 22, and then controls the pair of pressure shafts 11, 12 to apply a second load F2 to each of the first workpiece W10 and the second workpiece W20, while passing a second current X2 larger than the first current X1 through the pair of electrodes 21, 22.

[0049] (2) In the solid-state joining apparatus 1 of (1), as shown in FIG. 3, the control device 30 passes a first current X1 through a pair of electrodes 21, 22 for a first period, then stops the current flow, and then passes a second current X2 through the pair of electrodes 21, 22 for a second period.

[0050] (3) In the solid-state bonding apparatus 1 of (1), as shown in FIG. 6, the control device 30 supplies a first current X1 to the pair of electrodes 21, 22 for a first period, and then supplies a second current X2 to the pair of electrodes 21, 22 for a second period.

[0051] (4) The solid-state joining apparatus 1 according to any one of (1) to (3) further includes a sensor 40 capable of detecting a load acting on the first workpiece W10 and the second workpiece W20 from the pair of pressurizing shafts 11, 12. The control device 30 stops the supply of the first current X1 to the pair of electrodes in response to a detection value of the sensor 40 reaching a first threshold value, and stops the supply of the second current X2 to the pair of electrodes 21, 22 in response to a detection value of the sensor 40 reaching a second threshold value.

[0052] (5) The solid-state welding method disclosed herein is a solid-state welding method using a solid-state welding apparatus 1 including a pair of pressure shafts 11, 12 that press a first workpiece W10 and a second workpiece W20 made of metal from both sides in the thickness direction, a pair of electrodes 21, 22 that are respectively arranged around the pair of pressure shafts 11, 12, and a control device 30. The control device 30 executes the steps of: controlling the pair of pressure shafts 11, 12 to apply a first load F1 to each of the first workpiece W10 and the second workpiece W20 to bring them into contact with each other, while passing a first current X1 through the pair of electrodes 21, 22; and then controlling the pair of pressure shafts 11, 12 to apply a second load F2 to each of the first workpiece W10 and the second workpiece W20, while passing a second current X2 larger than the first current X1 through the pair of electrodes 21, 22.

[0053] According to the solid-state welding apparatus 1 and the solid-state welding method using the solid-state welding apparatus 1 of the present disclosure, the load during projection formation and the load during welding can be reduced by applying a first load F1 to each of the first workpiece W10 and the second workpiece W20 to bring them into contact with each other while passing a first current X1 through the pair of electrodes 21, 22. As a result, according to the solid-state welding apparatus 1 and the solid-state welding method of the present embodiment, the durability of the pair of pressure shafts 11, 12 is improved and it is possible to avoid an increase in size of the drive source (such as a servo press machine).

[0054] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not by the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0055] 1 solid-state joining device, 11, 12 pressure shaft, 11a, 12a pressing surface, 21, 22 electrode, 21a, 22a contact surface, 30 control device, 31 CPU, 32 memory, 40 sensor, F1 first load, F2 second load, X1 first current, X2 second current, W10, W20 workpiece, W11, W21 protrusion.

Claims

1. A pair of pressure shafts that press the first workpiece and the second workpiece made of metal from both sides in a thickness direction; A pair of electrodes disposed around the pair of pressure shafts, respectively; a control device; The control device includes: a first current is applied to the pair of electrodes while a first load is applied to each of the first workpiece and the second workpiece so as to contact each other by controlling the pair of pressure shafts; Next, a second current larger than the first current is passed through the pair of electrodes while a second load is applied to each of the first workpiece and the second workpiece by controlling the pair of pressure shafts.

2. 2. The solid-state joining apparatus according to claim 1, wherein the control device stops the flow of the first current to the pair of electrodes once after the first current has been applied to the pair of electrodes for a first period, and then applies the second current to the pair of electrodes for a second period.

3. The solid-state joining apparatus according to claim 1 , wherein the control device supplies the first current to the pair of electrodes for a first period, and subsequently supplies the second current to the pair of electrodes for a second period.

4. Further, a sensor capable of detecting a load acting on the first workpiece and the second workpiece from the pair of pressure shafts is provided, 4. The solid-state joining apparatus according to claim 1, wherein the control device stops the flow of the first current to the pair of electrodes in response to the detection value of the sensor becoming a first threshold value, and stops the flow of the second current to the pair of electrodes in response to the detection value of the sensor becoming a second threshold value.

5. A pair of pressure shafts that press the first workpiece and the second workpiece made of metal from both sides in a thickness direction; A pair of electrodes disposed around the pair of pressure shafts, respectively; A solid-state bonding method using a solid-state bonding apparatus including a control device, The control device includes: a step of applying a first load to each of the first workpiece and the second workpiece so as to bring the first workpiece and the second workpiece into contact with each other by controlling the pair of pressure shafts, while applying a first current to the pair of electrodes; Next, a step of applying a second load to each of the first workpiece and the second workpiece by controlling the pair of pressure shafts while passing a second current greater than the first current through the pair of electrodes is carried out.

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