Solid-phase bonding method and solid-phase bonding apparatus

Abstract

The objective is to suppress the deterioration of solid-phase bonding quality that can occur when current is passed from the electrode to the workpiece. [Solution] The solid-state bonding method comprises the steps of forming a protrusion on at least one of the first workpiece and the second workpiece (steps S1 to S3), starting to energize the first workpiece and the second workpiece while they are being pressed by a pair of pressure shafts (step S4), and ending the energization by a pair of electrodes (step S8) while the pressing by the pair of pressure shafts continues (steps S5 to S7, step S9) after the amount of indentation by the pair of pressure shafts in the thickness direction of the first workpiece and the second workpiece has reached a set value.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a solid-phase joining method and a solid-phase joining apparatus.

BACKGROUND ART

[0002] Japanese Patent Laid-Open No. 2024-171119 (Patent Document 1) discloses a resistance spot welding method that performs solid-phase joining on a workpiece to be joined by executing a protrusion forming step, an unloading step, an energization step, and a joining step, the method including a pressurizing shaft and electrodes.

[0003] In Patent Document 1, control is performed to energize the joining region of the workpiece from the electrodes to raise the temperature of the joining region, thereby softening the workpiece, and press the workpiece with the pressurizing shaft to join the workpiece.

[0004] In conventional solid-phase joining apparatuses, by adjusting the position of the electrodes with a device such as an air cylinder, the contact state between the workpiece and the electrodes can be maintained even when the workpiece is deformed due to softening of the workpiece caused by energization.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0005]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] However, in a solid-phase joining apparatus, when joining soft metals to each other, such as when joining aluminum and aluminum, there is a risk that the position adjustment of the electrodes cannot follow the rapid deformation of the workpiece whose temperature has been raised by energization.

[0007] When the electrode position adjustment cannot keep up with the rapid deformation of the workpiece due to the increase in temperature caused by the current, a gap will form between the workpiece and the electrode. When such a gap forms, a discharge occurs between the workpiece and the electrode. When such a discharge occurs, problems arise such as a decrease in the quality of solid-phase bonding, such as the formation of molten areas in the workpiece.

[0008] The purpose of this disclosure is to suppress the deterioration of solid-state bonding quality that may occur when current is passed from the electrode to the workpiece. [Means for solving the problem]

[0009] The solid-state bonding method of the present disclosure comprises the steps of: forming a protrusion on at least one of a first workpiece and a second workpiece, which overlap in the thickness direction, by pressing them with a pair of pressure shafts arranged on both sides in the thickness direction; starting to supply current to the first workpiece and the second workpiece from a pair of electrodes arranged around the pair of pressure shafts and in contact with the first workpiece and the second workpiece, while the first workpiece and the second workpiece are being pressed by the pair of pressure shafts; and ending the supply of current from the pair of electrodes while the pressing by the pair of pressure shafts continues, in accordance with the amount of indentation the pair of pressure shafts have made in the thickness direction of the first workpiece and the second workpiece since the pressing by the pair of pressure shafts began, which has reached a set value.

[0010] The solid-phase bonding apparatus of this disclosure comprises a pair of pressure shafts that press a first workpiece and a second workpiece that overlap in the thickness direction from both sides in the thickness direction, a pair of electrodes arranged around the pair of pressure shafts, and a control device that controls the pair of pressure shafts and the pair of electrodes. The control device presses the first workpiece and the second workpiece with the pair of pressure shafts to form a protrusion on at least one of the first workpiece and the second workpiece, and while the first workpiece and the second workpiece are being pressed by the pair of pressure shafts, it starts supplying current to the first workpiece and the second workpiece from the pair of electrodes that are in contact with the first workpiece and the second workpiece, and controls the current supply from the pair of electrodes to end while the pressing by the pair of pressure shafts continues, in accordance with the amount of indentation the pair of pressure shafts have made in the thickness direction of the first workpiece and the second workpiece since the pressing by the pair of pressure shafts began to reach a set value. [Effects of the Invention]

[0011] According to this disclosure, in solid-state bonding, when a pair of electrodes are supplying current to a first workpiece and a second workpiece while the workpieces are being pressed by a pair of pressure shafts, the current supplied by the pair of electrodes is terminated while the pressing by the pair of pressure shafts continues, in accordance with the amount of indentation reached by the pair of pressure shafts. In this way, since the current supplied by the pair of electrodes is terminated in accordance with the amount of indentation reached by the pair of pressure shafts, even if a gap is subsequently created between the first workpieces and the second workpieces and the pair of electrodes due to deformation of the workpieces, a discharge phenomenon can be prevented. Therefore, according to this disclosure, it is possible to prevent a discharge phenomenon caused by a gap between the first workpieces and the second workpieces and the pair of electrodes, and to suppress a deterioration in the quality of the solid-state bonding that may occur when current is supplied from the electrodes to the workpieces. [Brief explanation of the drawing]

[0012] [Figure 1] This figure schematically shows a solid-phase bonding apparatus for performing the solid-phase bonding method according to the embodiment. [Figure 2] This figure shows the change in the contact state between the workpiece and the electrode during solid-state bonding. [Figure 3] This figure shows the relationship between the amount of pressure applied by a pair of pressurizing shafts and the control of current flow from a pair of electrodes in the solid-state bonding method according to this embodiment. [Figure 4] This flowchart shows the control flow of the solid-state bonding method according to this embodiment. [Modes for carrying out the invention]

[0013] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated. Several embodiments will be described below, including modified examples. It was intended from the outset that the configurations described in the embodiments and the configurations described as modified examples would be appropriately combined.

[0014] <Explanation of the configuration of the solid-phase bonding apparatus 1> Figure 1 is a schematic diagram showing a solid-phase bonding apparatus 1 that performs the solid-phase bonding method according to the embodiment. The solid-phase bonding apparatus 1 is a device that bonds multiple workpieces W10 and W20 without melting them by applying an electric current to the workpieces W10 and W20 that are stacked on top of each other, thereby forming a softened region as a bonding region at the interface of the multiple workpieces W10 and W20, and then plastically deforming the softened region.

[0015] Multiple workpieces W10, W20 include a first workpiece W10 and a second workpiece W20. Each workpiece W10, W20 is, for example, flat. The first workpiece W10 and the second workpiece W20 are stacked in their thickness direction.

[0016] In this embodiment, the first workpiece W10 and the second workpiece W20 are made of the same material. In this embodiment, both the first workpiece W10 and the second workpiece W20 are made of an aluminum alloy.

[0017] Note that the first workpiece W10 and the second workpiece W20 are not limited to aluminum alloys, and may be any soft metal having relatively low deformation resistance. Accordingly, the first workpiece W10 and the second workpiece W20 may be soft metals other than aluminum alloys, such as aluminum, gold, and silver. The first workpiece W10 and the second workpiece W20 may be metals of the same material, for example, when aluminum alloys are joined to each other, or may be metals of different materials, for example, when gold and silver are joined together.

[0018] Note that each of the workpieces W10 and W20 may be made of a material other than metal, as long as the material has electrical conductivity and is suitable for solid-phase welding.

[0019] As shown in Figure 1, a solid-phase welding apparatus 1 includes a solid-phase welding device 10, a control device 30, a power supply device 35, a drive device 13, a first adjustment device 14, a second adjustment device 15, a first air cylinder 16, a second air cylinder 17, and an input device 5. The solid-phase welding device 10 includes a pair of pressurizing shafts 11, 12, a pair of electrodes 21, 22, a pressure sensor 40, and a movement amount sensor 41.

[0020] The pair of pressurizing shafts 11, 12 includes a first pressurizing shaft 11 and a second pressurizing shaft 12. The pair of pressurizing shafts 11, 12 is capable of pressurizing the stacked plate-shaped first workpiece W10 and second workpiece W20 from both sides in the thickness direction. The first pressurizing shaft 11 is driven by the drive device 13. The second pressurizing shaft 12 is fixed. The drive device 13 includes, for example, a servomotor. Note that both the first pressurizing shaft 11 and the second pressurizing shaft 12 may be driven by separate drive devices or a common drive device.

[0021] The first pressurizing shaft 11 can press the first workpiece W10 such that the first workpiece W10 is plastically deformed. The first pressurizing shaft 11 is made of, for example, tungsten carbide. In the present embodiment, the first pressurizing shaft 11 is formed in an elongated cylindrical shape. The first pressurizing shaft 11 has a pressing surface 11a that presses the first workpiece W10. The pressing surface 11a is an end face of the first pressurizing shaft 11. The pressing surface 11a is formed in a circular shape.

[0022] The second pressurizing shaft 12 has the same configuration as that of the first pressurizing shaft 11. The second pressurizing shaft 12 is arranged in an attitude in which the central axis of the second pressurizing shaft 12 is located on the extension line of the central axis of the first pressurizing shaft 11, and the pressing surface 12a of the second pressurizing shaft 12 faces the pressing surface 11a of the first pressurizing shaft 11. The first pressurizing shaft 11 and the second pressurizing shaft 12 may have a shape other than a cylindrical shape.

[0023] The pressure sensor 40 is a sensor that detects the pressure applied to the first pressurizing shaft 11. The pressure sensor 40 is provided, for example, on the first pressurizing shaft 11. In the present embodiment, a load cell is used as the pressure sensor 40. The installation location of the pressure sensor 40 is not limited to the first pressurizing shaft 11, and may be provided on the drive device 13 or the like. The pressure sensor 40 may be provided on both the first pressurizing shaft 11 and the second pressurizing shaft 12.

[0024] The movement amount sensor 41 is a sensor that detects the movement amount of the first pressurizing shaft 11 in the axial length direction (hereinafter also referred to as the indentation amount). The movement amount sensor 41 is provided, for example, on the first pressurizing shaft 11. In the present embodiment, a linear encoder is used as the movement amount sensor 41. In the case of a configuration in which the second pressurizing shaft 12 moves, the movement amount sensor 41 may be provided on both the first pressurizing shaft 11 and the second pressurizing shaft 12.

[0025] The pair of electrodes 21 and 22 includes a first electrode 21 and a second electrode 22. The pair of electrodes 21 and 22 can energize the first workpiece W10 and the second workpiece W20 in a state of being in contact with the first workpiece W10 and the second workpiece W20. In a state where the pair of electrodes 21 and 22 are in contact with the first workpiece W10 and the second workpiece W20, a voltage is applied from the power supply device 35 to the pair of electrodes 21 and 22, whereby current is supplied to the first electrode 21, the first workpiece W10, the second workpiece W20, and the second electrode 22.

[0026] The first electrode 21 is capable of contacting the portion of the first workpiece W10 that is pressurized by the first pressurizing shaft 11. In this embodiment, the first electrode 21 is formed in a cylindrical shape that surrounds the first pressurizing shaft 11. A gap is provided between the inner circumferential surface of the first electrode 21 and the outer circumferential surface of the first pressurizing 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. However, the shape of the contact surface 21a is not limited to an annular shape.

[0027] The second electrode 22 is capable of contacting the portion of the second workpiece W20 that is pressurized by the second pressurizing shaft 12. In this embodiment, the second electrode 22 is formed in a cylindrical shape that surrounds the second pressurizing shaft 12. A gap is provided between the inner circumferential surface of the second electrode 22 and the outer circumferential surface of the second pressurizing shaft 12. The second electrode 22 is made of, for example, copper. The second electrode 22 has a contact surface 22a that contacts the second workpiece W20. The contact surface 22a is formed in an annular shape. However, the shape of the contact surface 22a is not limited to an annular shape. The second electrode 22 is positioned such that its central axis lies on the extension of the central axis of the first electrode 21, and its contact surface 22a faces the contact surface 21a of the first electrode 21.

[0028] The position of the first electrode 21 in the thickness direction of the first workpiece W10 is adjusted by the first adjustment device 14 and the first air cylinder 16. The position of the second electrode 22 in the thickness direction of the second workpiece W20 is adjusted by the second adjustment device 15 and the second air cylinder 17. The first adjustment device 14 is a device that adjusts the position of the first air cylinder 16 itself. The second adjustment device 15 is a device that adjusts the position of the second air cylinder 17 itself.

[0029] The first air cylinder 16 is a device in which a piston located inside the cylinder operates in accordance with the air pressure inside the cylinder, and the piston rod moves in the axial direction in accordance with the movement of the piston. The tip of the piston rod of the first air cylinder 16 is connected to the first electrode 21. In the first air cylinder 16, the piston rod can move in the axial direction so that the first electrode 21 comes into contact with the first workpiece W10 due to the internal pressure of the cylinder.

[0030] The position of the first air cylinder 16 itself is adjusted by the first adjustment device 14 so that, in the initial state, the piston rod is in the reference position (the position of the piston rod when air at a reference pressure is sealed inside the cylinder), and the first electrode 21 connected to the piston rod contacts the first workpiece W10 with a predetermined force.

[0031] The first adjustment device 14 consists of a position adjustment mechanism that can change the installation position of the first air cylinder 16 itself using a drive source such as a motor.

[0032] In the first air cylinder 16, when the first workpiece W10 deforms in a direction that moves toward the first air cylinder 16, the piston rod moves in a direction that compresses the air inside the cylinder, causing the position of the first electrode 21 to change in accordance with the deformation of the first workpiece W10 and maintain contact with the first workpiece W10. On the other hand, in the first air cylinder 16, when the first workpiece W10 deforms in a direction that moves toward the first air cylinder 16, the piston rod moves in a direction that expands the air inside the cylinder, thereby maintaining contact between the first electrode 21 and the first workpiece W10.

[0033] The second air cylinder 17, like the first air cylinder 16, is a device in which a piston located inside the cylinder operates in accordance with the air pressure inside the cylinder, and the piston rod moves in the axial direction in accordance with the movement of the piston. In the second air cylinder 17, the tip of the piston rod is connected to the second electrode 22. In the second air cylinder 17, the piston rod can move in the axial direction so that the second electrode 22 comes into contact with the second workpiece W20 due to the internal pressure of the cylinder.

[0034] The position of the second air cylinder 17 itself is adjusted by the second adjustment device 15 so that, in the initial state, the piston rod is in the reference position (the position of the piston rod when air at a reference pressure is sealed inside the cylinder), and the second electrode 22 connected to the piston rod contacts the second workpiece W20 with a predetermined force.

[0035] The second adjustment device 15 consists of a position adjustment mechanism that can change the installation position of the second air cylinder 17 itself using a drive source such as a motor.

[0036] In the second air cylinder 17, when the second workpiece W20 deforms in a direction that moves it toward the second air cylinder 17, the piston rod moves in a direction that compresses the air inside the cylinder, causing the position of the second electrode 22 to change in accordance with the deformation of the second workpiece W20, and maintaining the electrode 22 in contact with the second workpiece W20. On the other hand, in the second air cylinder 17, when the second workpiece W20 deforms in a direction that moves it toward the second air cylinder 17, the piston rod moves in a direction that expands the air inside the cylinder, thereby maintaining the second electrode 22 in contact with the second workpiece W20.

[0037] The control device 30 comprises an arithmetic unit 31, a memory 32, a storage device 33, and an input / output interface 34. These components are connected via a bus.

[0038] The arithmetic unit 31 is a computing entity (computer) that performs predetermined processing. The arithmetic unit 31 is composed of a processor such as a CPU (Central Processing Unit), MPU (Micro-Processing Unit), TPU (Tensor Processing Unit), or GPU (Graphics Processing Unit). While a processor, as an example of the arithmetic unit 31, has the function of performing predetermined processing by executing a predetermined program, some or all of these functions may be implemented using dedicated hardware circuits such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array). The term "processor" is not limited to processors in the narrow sense that execute processing using a stored-program method, such as a CPU, MPU, TPU, or GPU, but may also include hardwired circuits such as ASICs or FPGAs. Furthermore, the arithmetic unit 31 is not limited to von Neumann type computers such as CPUs or GPUs, but may also consist of non-von Neumann type computers such as quantum computers or optical computers. The arithmetic unit 31 described above can also be read as a processing circuitry that performs predetermined processing. The arithmetic unit 31 may consist of one chip or multiple chips. Furthermore, the processor and associated processing circuits may consist of multiple computers interconnected by wired or wireless connections via a local area network or wireless network. The processor and associated processing circuits may also consist of a cloud computer that remotely performs calculations based on input data and outputs the calculation results to other devices located at a distance.

[0039] The memory 32 includes a storage area (for example, a working area) for storing program code or work memory when the arithmetic unit 31 executes various programs. Examples of memory 32 include volatile memory such as DRAM and SRAM, or non-volatile memory such as ROM and flash memory.

[0040] The storage device 33 stores various programs or data executed by the arithmetic unit 31. For example, the storage device 33 stores control programs 330 that control various devices executed by the arithmetic unit 31. The storage device 33 may be one or more non-transitory computer-readable media or one or more computer-readable storage media. Examples of storage devices 33 include HDDs (Hard Disk Drives) and SSDs (Solid State Drives).

[0041] The input / output interface 34 receives data detected by sensors such as a pressure sensor 40 and a displacement sensor 41. An input device 5 is connected to the control device 30. The input device 5 consists of one or more devices capable of inputting data, such as a keyboard, mouse, and touch panel. The data input from the input device can be input to the arithmetic unit 31 and memory 32 via the input / output interface 34.

[0042] The control device 30 controls the stroke of the first pressurizing shaft 11 by controlling the drive device 13. The control device 30 controls the position of the first air cylinder 16 by controlling the first adjustment device 14. The control device 30 controls the position of the second air cylinder 17 by controlling the second adjustment device 15. The control device 30 controls the current supplied to the pair of electrodes 21 and 22 by controlling the power supply device 35.

[0043] Specifically, the control device 30 controls the drive device 13 to move the first pressurizing shaft 11 toward the first workpiece W10, thereby controlling the load F acting on the first workpiece W10 and the second workpiece W20 from each of the pair of pressurizing shafts 11 and 12, and the amount of pressure applied by the pair of pressurizing shafts 11 and 12. The control device 30 adjusts the position of the first air cylinder 16 itself by controlling the first adjustment device 14 so that the first electrode 21 can contact the first workpiece W10. The control device 30 adjusts the position of the second air cylinder 17 itself by controlling the second adjustment device 15 so that the second electrode 22 can contact the second workpiece W20. The control device 30 controls the power supply device 35 to control the current supplied from the pair of electrodes 21 and 22 to the first workpiece W10 and the second workpiece W20.

[0044] The control device 30 controls the drive device 13 so that a load F is applied to the first workpiece W10 and the second workpiece W20 from a pair of pressurizing shafts 11 and 12. As a result, protrusions 6 and 7 are formed on the first workpiece W10 and the second workpiece W20, for example, as shown in Figure 2(C).

[0045] The control device 30 then controls the power supply device 35 so that, in addition to applying pressure (pressure) to the first workpiece W10 and the second workpiece W20 by the pressure shafts 11 and 12, the pair of electrodes 21 and 22 energize the first workpiece W10 and the second workpiece W20. As a result, current flows through the first workpiece W10 and the second workpiece W20. Specifically, the control device 30 controls the power supply device 35 so that current flows through the first workpiece W10 and the second workpiece W20, with the contact surface 21a of the first electrode 21 in contact with the area surrounding the part of the first workpiece W10 that is pressed by the first pressure shaft 11, and the contact surface 22a of the second electrode 22 in contact with the area surrounding the part of the second workpiece W20 that is pressed by the second pressure shaft 12.

[0046] <Explanation of changes in the contact state between the workpiece and the electrode during solid-state bonding> Next, we will explain the change in the contact state between the workpiece and the electrode during solid-phase bonding. In the solid-phase bonding apparatus 1, when bonding a first workpiece W10 and a second workpiece W20, the protrusion formation process is performed first, followed by the bonding process.

[0047] Figure 2 shows the changes in the contact state between the workpiece and the electrode during solid-phase bonding. Figures 2(A) to 2(E) show the process by which the contact state between the first workpiece W10 and the first electrode 21, and the contact state between the second workpiece W20 and the second electrode 22, changes during solid-phase bonding.

[0048] As shown in Figure 2(A), in the stage before the protrusion formation process is started, the plate-shaped first workpiece W10 and the plate-shaped second workpiece W20 are arranged so that they overlap in the thickness direction. As shown in Figure 2(A), in the stage before the protrusion formation process is started, the control device 30 controls the first adjustment device 14 and the second adjustment device 15 so that the first workpiece W10 and the first electrode 21 are in contact, and the second workpiece W20 and the second electrode 22 are in contact.

[0049] In the projection formation process, the control device 30 performs the following control. As shown in Figure 2(A), the control device 30 moves the fixed second pressurizing shaft 12 to a position where it is in contact with the second workpiece W20, and the movable first pressurizing shaft 11 to a position where it is in contact with the first workpiece W10, as indicated by the dashed arrow. In solid-state bonding, the position of the first pressurizing shaft 11 where the first pressurizing shaft 11 is in contact with the first workpiece W10 and the second pressurizing shaft 12 is in contact with the second workpiece W20, as shown in Figure 2(A), is the starting position for pressing.

[0050] Furthermore, if both the first pressurizing shaft 11 and the second pressurizing shaft 12 are movable, during the projection forming process, the control device 30 controls the movement of the first pressurizing shaft 11 to a position where it contacts the first workpiece W10, and the movement of the second pressurizing shaft 12 to a position where it contacts the second workpiece W20.

[0051] In the following description, an example is given in which the movable first pressurizing shaft 11 is operated in the projection formation process and the joining process. However, when both the first pressurizing shaft 11 and the second pressurizing shaft 12 are movable, the control device 30 controls the second pressurizing shaft 12 to perform the same operation as the first pressurizing shaft 11, as described below.

[0052] The control device 30 then controls the drive device 13 to push the pair of pressurizing shafts 11 and 12 from the initial pushing position shown in Figure 2(A) to a preset projection formation position as shown in Figure 2(C). As a result, a load F acts on the pair of pressurizing shafts 11 and 12, causing the first workpiece W10 and the second workpiece W20 to deform, as shown in Figures 2(B) and 2(C), forming a projection 6 on the first workpiece W10 and a projection 7 on the second workpiece W20.

[0053] As shown in Figure 2(C), the control device 30 performs a protrusion process in which a protrusion 6 is formed on the first workpiece W10 and a protrusion 7 is formed on the second workpiece W20, and then performs a joining process.

[0054] During the bonding process, the control device 30 performs the following control. In the state shown in Figure 2(C), the control device 30 controls the power supply 35 and supplies current from the pair of electrodes 21 and 22 to the first workpiece W10 and the second workpiece W20 for bonding.

[0055] Furthermore, in the state shown in Figure 2(C), the control device 30 controls the drive device 13 and starts the operation of pushing the pair of pressure shafts 11 and 12 to a preset joining position. As a result, the pair of pressure shafts 11 and 12 are pushed to the joining position, and the first workpiece W10 and the second workpiece W20 are joined together, after going through the states shown in Figures 2(D) and 2(E).

[0056] Thus, in the joining process, the control device 30 controls the operation of pushing a pair of pressure shafts 11 and 12 to the joining position while energizing the first workpiece W10 and the second workpiece W20 from a pair of electrodes 21 and 22. As a result, in the joining process, a softened region is formed at the interface between the first workpiece W10 and the second workpiece W20 as a joining region, and a load F is applied to the softened region by pushing in the pair of pressure shafts 11 and 12, causing the softened region to plastically deform, thereby joining the first workpiece W10 and the second workpiece W20 in a solid state without melting.

[0057] During the bonding process, current is supplied to the first workpiece W10 and the second workpiece W20 from a pair of electrodes 21 and 22. However, as the first workpiece W10 and the second workpiece W20 soften, they may rapidly change shape from, for example, the shape shown in Figure 2(D) to the shape shown in Figure 2(E).

[0058] If the first workpiece W10 changes rapidly in this manner, the first air cylinder 16 may not be able to keep up with the position of the first electrode 21, and a gap 8 may occur between the first workpiece W10 and the electrode 21. Similarly, if the second workpiece W20 changes rapidly in this manner, the second air cylinder 17 may not be able to keep up with the position of the second electrode 22, and a gap 9 may occur between the second workpiece W20 and the electrode 22.

[0059] If a gap 8 occurs between the first workpiece W10 and the first electrode 21, and a voltage is applied to the first electrode 21, a discharge may occur between the first workpiece W10 and the first electrode 21. Similarly, if a gap 9 occurs between the second workpiece W20 and the second electrode 22, and a voltage is applied to the second electrode 22, a discharge may occur between the second workpiece W20 and the second electrode 22. Such discharges may degrade the quality of the solid-phase bonding.

[0060] Therefore, in the solid-phase bonding apparatus 1 of this embodiment, the control device 30 controls the energization from the first electrode 21 and the second electrode 22 before at least one of the gaps 8 between the first workpiece W10 and the first electrode 21, and the gap 9 between the second workpiece W20 and the second electrode 22 occurs.

[0061] Specifically, in this embodiment, the control device 30 performs the following control in accordance with the confirmation through experiments, etc., that there is a relationship between the amount of indentation of the pair of pressurizing shafts 11, 12 and the occurrence of gaps 8, 9. During the joining process, the control device 30 performs control to terminate the energization from the first electrode 21 and the second electrode 22 when the amount of indentation of the pair of pressurizing shafts 11, 12 reaches a set value which is the amount of indentation before at least one of the gaps 8 between the first workpiece W10 and the first electrode 21 and the gap 9 between the second workpiece W20 and the second electrode 22 occurs.

[0062] <Relationship between indentation amount and current control in solid-state bonding> Next, the relationship between the amount of pressure applied by the pair of pressurizing shafts 11 and 12 in the solid-state bonding method according to this embodiment and the control of current flow from the pair of electrodes 21 and 22 will be explained.

[0063] Figure 3 shows the relationship between the amount of pressure applied by a pair of pressurizing shafts 11 and 12 and the control of current supply from a pair of electrodes 21 and 22 in the solid-state bonding method according to this embodiment.

[0064] Figure 3 shows the relationship between the amount of indentation of a pair of pressure shafts 11 and 12, the pressing load corresponding to that amount of indentation, and the energization control from a pair of electrodes 21 and 22 corresponding to the amount of indentation, over the period from time t0 to time t6.

[0065] Figure 3(A) shows the indentation amount (mm) of a pair of pressure shafts 11 and 12 over time. Figure 3(B) shows the load (kN), which is the pressing load acting on the first workpiece W10 and the second workpiece W20, over time, corresponding to the indentation amount of the pair of pressure shafts 11 and 12 as shown in Figure 3(A). Figure 3(C) shows the current (kA) supplied from a pair of electrodes 21 and 22 to the first workpiece W10 and the second workpiece W20.

[0066] When the projection formation process in solid-state bonding is performed, the control device 30 controls the movement of the first pressurizing shaft 11 during the period from time t0 to time t1, so that the arrangement of the pair of pressurizing shafts 11 and 12 becomes the indentation start position shown in Figure 2(A), as shown in the period leading up to the first timing 51 in Figure 3(A). In Figure 3(A), the indentation amount is shown with the indentation amount at the indentation start position shown in Figure 2(A) set as the initial value a (0 mm).

[0067] When the protrusion formation process is performed, as shown in Figure 3(A), after the amount of indentation becomes constant during the period from time t1 to time t2, at time t2, the control device 30 starts control to increase the amount of indentation from the initial value a to the first set value b. The first set value b is the set value of the amount of indentation set as the target value for forming protrusions 6 and 7 as shown in Figure 2(C). The first set value b is set based on workpiece data, including the plate thickness and material of the first workpiece W10 and the second workpiece W20.

[0068] At the second timing 52, when the indentation amount shown in Figure 3(A) is increasing from the initial value a, protrusions 6 and 7 begin to form on the first workpiece W10 and the second workpiece W20, as shown in Figure 2(B). Then, at time t3, when the indentation amount shown in Figure 3(A) reaches the first set value b, which is the third timing 53, the protrusions 6 and 7 on the first workpiece W10 and the second workpiece W20 become the final shape in the protrusion formation process, as shown in Figure 2(C).

[0069] At the third timing 53, when the indentation amount shown in Figure 3(A) reaches the first set value b, the projection-forming load e acts on the pair of pressurizing shafts 11 and 12, as shown in Figure 3(B). During the projection-forming process, the indentation amount remains constant from time t3 to time t4.

[0070] As shown in Figure 2(D), when the bonding process in solid-state bonding is performed, the control device 30 executes a control at time t4, as shown in Figure 3(C), to start supplying current g (kA) for bonding from the pair of electrodes 21 and 22 to the first workpiece W10 and the second workpiece W20.

[0071] Furthermore, when the bonding process in solid-state bonding is performed as shown in Figure 2(D), the control device 30 starts a control at time t4 to increase the indentation amount from the first set value b to the third set value d, as shown in the fourth timing 54 in Figure 3(A). The third set value d is the indentation amount that reaches the bonding position in solid-state bonding as explained using Figure 2. The third set value d is set based on workpiece data, including the plate thickness and material of the first workpiece W10 and the second workpiece W20.

[0072] When the amount of indentation reaches the third set value d, a joining load f acts on the pair of pressurizing shafts 11 and 12, as shown in Figure 3(B). In the joining process, this joining load f acts on the pair of pressurizing shafts 11 and 12, making it possible to complete the joining of the first workpiece W10 and the second workpiece W20.

[0073] Thus, in the joining process, after time t4, the energization shown in Figure 3(C) and the pressing shown in Figure 3(A) are initiated. Then, in the joining process, as shown in Figure 3(A), if the amount of pressing reaches the second set value c at time t5, for example, the control device 30 executes a control to terminate the energization from the pair of electrodes 21 and 22 to the first workpiece W10 and the second workpiece W20.

[0074] The second setting value c is a setting value for the indentation amount set to terminate the energization before at least one of the gaps 8 between the first workpiece W10 and the first electrode 21, and the gap 9 between the second workpiece W20 and the second electrode 22 occurs, as explained with reference to Figure 2. As mentioned above, this second setting value c is a setting value for the indentation amount determined based on measurement data obtained from an experiment in which the relationship between the indentation amount of the pair of pressurizing shafts 11 and 12 and the occurrence of gaps 8 and 9 in the first workpiece W10 and the second workpiece W20 was measured and analyzed.

[0075] The second setting value c is the amount of indentation before at least one of the gap 8 between the first workpiece W10 and the first electrode 21, and the gap 9 between the second workpiece W20 and the second electrode 22 occurs. Based on data measured in advance regarding the relationship between the amount of indentation of the pair of pressurizing shafts 11 and 12 and the presence or absence of discharge between the electrodes 21 and 22 and the first workpiece W10 and the second workpiece W20, the setting value is set to an amount of indentation within a range that does not hinder the softening of the bonding area between the first workpiece W10 and the second workpiece W20 due to the energization by the pair of electrodes 21 and 22.

[0076] Thus, when the amount of indentation reaches the second set value c and control is executed to terminate the energization, the indentation control of the pair of pressurizing shafts 11 and 12 described above is continued by the control device 30.

[0077] After the indentation amount reaches the second set value c, for example, at the fifth timing 55 as shown in Figure 3(A), at least one of the gaps 8 between the first workpiece W10 and the first electrode 21, and the gap 9 between the second workpiece W20 and the second electrode 22 may occur, as shown in Figure 2(E).

[0078] However, in the solid-state bonding method of this embodiment, even if such a gap occurs, the control device 30 executes a control to terminate the energization from the pair of electrodes 21 and 22 to the first workpiece W10 and the second workpiece W20 before such a gap occurs, thereby preventing the occurrence of discharge caused by the occurrence of such a gap. The effect of preventing such discharge is particularly noticeable when bonding soft metals, such as when both the first workpiece W10 and the second workpiece W20 are made of aluminum alloy. Furthermore, this effect becomes more pronounced as the first workpiece W10 and the second workpiece W20 to be bonded become softer.

[0079] <Description of control of the solid-phase bonding method according to this embodiment> Next, the control flow of the solid-phase bonding method according to this embodiment will be described. Figure 4 is a flowchart showing the control flow of the solid-phase bonding method according to this embodiment. The control described below is performed by the control device 30, in which the arithmetic unit 31 reads and executes the control program stored in the memory 32.

[0080] In step S1, the control device 30 controls the drive device 13 so that the pushing operation of a pair of pressure shafts 11 and 12 is started in order to form protrusions such as the protrusions 6 and 7 shown in Figure 2(C) on the first workpiece W10 and the second workpiece W20 during the protrusion formation process.

[0081] In step S2, the control device 30 determines whether the amount of indentation detected by the movement amount sensor 41 has reached the first set value (first set value b in Figure 3(A)) for forming a protrusion in the protrusion formation process. If the control device 30 determines in step S2 that the amount of indentation has not reached the first set value, it determines that the formation of the protrusion is not yet complete in the protrusion formation process, and in step S3, it continues the indentation operation of the pair of pressure shafts 11 and 12 for forming the protrusion in the protrusion formation process. After step S3, the process returns to step S2.

[0082] If the control device 30 determines in step S2 that the amount of indentation has reached the first set value, it determines that the formation of the protrusions in the protrusion formation process is complete, and in step S4 controls the power supply device 35 so that current is supplied from the pair of electrodes 21 and 22 to the first workpiece W10 and the second workpiece W20. In step S4, the control device 30 starts the bonding process.

[0083] In step S5, the control device 30 controls the drive device 13 so that the pushing operation of the pair of pressure shafts 11 and 12 for joining the first workpiece W10 and the second workpiece W20 in the joining process is initiated.

[0084] In step S6, the control device 30 determines whether the amount of indentation detected by the movement amount sensor 41 has reached the second set value (second set value c in Figure 3(A)) for ending the energization in the joining process. If the control device 30 determines in step S6 that the amount of indentation has not reached the second set value, it determines that it is not a state to end the energization in the joining process, and in step S7, it continues the indentation operation of the pair of pressure shafts 11 and 12 in the joining process. After step S7, the process returns to step S6.

[0085] If the control device 30 determines in step S6 that the amount of indentation has reached the second set value, it determines that it is time to terminate the energization in the joining process, and in step S8 controls the power supply device 35 so that the energization from the pair of electrodes 21 and 22 to the first workpiece W10 and the second workpiece W20 is terminated.

[0086] In step S9, the control device 30 continues the pressing operation of the pair of pressure shafts 11 and 12 in the joining process until the amount of pressing reaches the third set value (third set value d in Figure (A)) and the joining of the first workpiece W10 and the second workpiece W20 is completed. After that, the control device 30 terminates the processes in the projection formation process and the joining process.

[0087] In Figure 4, steps S1 to S3 are included in the protrusion formation process, and steps S4 to S9 are included in the joining process.

[0088] As shown in Figure 4, the control device 30 performs the control to terminate the energization from the pair of electrodes 21 and 22 to the first workpiece W10 and the second workpiece W20 before at least one of the gaps 8 between the first workpiece W10 and the first electrode 21, and the gap 9 between the second workpiece W20 and the second electrode 22 occurs during solid-phase bonding, as shown in Figure 2(E). This prevents the occurrence of discharge caused by the formation of such gaps 8 and 9.

[0089] <Explanation of an experimental example of a second setting value that stops the power supply according to the amount of pressure applied> Next, we will explain an experimental example of a second setting value that stops the current flow according to the amount of indentation. The experimental data when solid-state bonding of aluminum alloys as the first workpiece W10 and the second workpiece W20 using the solid-state bonding apparatus 1 shown in Figure 1 is as follows.

[0090] First, in the solid-phase bonding apparatus 1, a first experiment was conducted in which the control to terminate the energization by the pair of electrodes 21 and 22 as described above during the bonding process was not performed. In the first experiment, the same type of aluminum alloy was used as the first workpiece W10 and the second workpiece W20, the current value of the energization by the pair of electrodes 21 and 22 during the bonding process was set to 17kA, and the pushing speed of the pair of pressure shafts 11 and 12 was set to 20mm / sec. The control device 30 performed control to push the pair of pressure shafts 11 and 12 until a discharge state occurred.

[0091] In this first experiment, when the pressing operation using the pair of pressurizing shafts 11 and 12 was started from the pressing start position as shown in Figure 2(A), if the amount of pressing detected by the movement sensor 41 exceeded 1.5 mm, a gap was created between the first workpiece W10 and the first electrode 21, and between the second workpiece W20 and the first electrode 21, causing a discharge.

[0092] Therefore, in the solid-phase bonding apparatus 1, the second setting value for the indentation amount that stops the energization was set to 1.5 mm, and a second experiment was conducted in which control was performed to terminate the energization by the pair of electrodes 21 and 22 as described above during the bonding process. The conditions for the materials of the first workpiece W10 and the second workpiece W20, the current value and row of the energization by the pair of electrodes 21 and 22 during the bonding process, and the indentation speed of the pair of pressurizing shafts 11 and 12 in the second experiment were the same as in the first experiment.

[0093] In this second experiment, when the indentation amount reached a second set value of 1.5 mm during the bonding process, the energization by the pair of electrodes 21 and 22 was terminated, and the indentation operation by the pair of pressure shafts 11 and 12 continued, completing the solid-state bonding of the first workpiece W10 and the second workpiece W20. In this second experiment, when the indentation amount exceeded 1.5 mm, no gap was created between the first workpiece W10 and the first electrode 21, nor between the second workpiece W20 and the first electrode 21, and no discharge occurred.

[0094] In the second experiment, based on the experimental data from the first experiment, the amount of indentation to be set as the second setting value was determined, and the determined amount of indentation was set as the second setting value. As a result of performing the solid-phase bonding method according to this embodiment, no gaps were created between the first workpiece W10 and the first electrode 21, nor between the second workpiece W20 and the first electrode 21, and no discharge occurred. As a result, the solid-phase bonding result was of good quality.

[0095] Therefore, in the solid-state bonding method according to this embodiment, a second setting value for stopping the current supply according to the amount of indentation can be determined and set based on experimental data from such experiments.

[0096] <Examples of effects obtained by the embodiment> (1) In solid-state bonding, as shown in Figure 4, when the first workpiece W10 and the second workpiece W20 are pressed by a pair of pressure shafts 11 and 12, and current is supplied to the first workpiece W10 and the second workpiece W20 from a pair of electrodes 21 and 22, the current supplied by the pair of electrodes 21 and 22 is terminated when the amount of pressure applied by the pair of pressure shafts 11 and 12 reaches a second set value c, while the pressure applied by the pair of pressure shafts 11 and 12 continues. In this way, the current supplied by the pair of electrodes 21 and 22 is terminated when the amount of pressure applied by the pair of pressure shafts 11 and 12 reaches a second set value c, so that even if gaps 8 and 9 are created between the first workpiece W10 and the second workpiece W20 and the pair of electrodes 21 and 22 due to deformation of the first workpiece W10 and the second workpiece, a discharge phenomenon can be prevented. Therefore, according to this disclosure, it is possible to prevent discharge phenomena caused by gaps 8, 9 between the first workpiece W10 and the second workpiece W20 and the pair of electrodes 21, 22, and to suppress the deterioration of solid-phase bonding quality that may occur when current is passed from the pair of electrodes 21, 22 to the first workpiece W10 and the second workpiece W20.

[0097] As shown in Figure 3(A), the second set value c is set to the amount of indentation before a gap is formed between at least one of the first workpiece W10 and the second workpiece W20 and the pair of electrodes 21 and 22, where discharge can occur, due to the deformation of at least one of the first workpiece W10 and the second workpiece W20. Therefore, the discharge phenomenon caused by the gaps 8 and 9 between the first workpiece W10 and the second workpiece W20 and the pair of electrodes 21 and 22 can be reliably suppressed.

[0098] As shown in Figure 3(A), the second setting value c is set to a value for the amount of indentation within a range that does not hinder the softening of the bonding area between the first workpiece W10 and the second workpiece W20 due to the energization by the pair of electrodes 21 and 22, based on data measured in advance regarding the relationship between the amount of indentation of the pair of pressurizing shafts 11 and 12 and the presence or absence of discharge. Therefore, it is possible to reliably suppress the discharge phenomenon caused by the gaps 8 and 9 between the first workpiece W10 and the second workpiece W20 and the pair of electrodes 21 and 22 without affecting the softening of the bonding area in solid-state bonding.

[0099] When the first workpiece W10 and the second workpiece W20 are made of a soft metal such as an aluminum alloy, the discharge phenomenon caused by the gaps 8 and 9 between the first workpiece W10 and the second workpiece W20 and the pair of electrodes 21 and 22 can be suppressed.

[0100] When the first workpiece W10 and the second workpiece W20 are made of the same soft metal, such as aluminum alloys, the discharge phenomenon caused by the gaps 8 and 9 between the first workpiece W10, the second workpiece W20, and the pair of electrodes 21 and 22 can be suppressed.

[0101] For example, in soft metals containing aluminum, such as aluminum alloys, aluminum, gold, and silver, the discharge phenomenon caused by the gaps 8 and 9 between the first workpiece W10 and the second workpiece W20 and the pair of electrodes can be suppressed.

[0102] <Explanation of variations> (1) The second setting value c mentioned above is set to the amount of indentation at which control is executed to terminate the energization from the pair of electrodes 21 and 22 to the first workpiece W10 and the second workpiece W20 when the indentation amount reaches that point.

[0103] Such a second setting value c may be set to a pressing amount less than the pressing amount determined by detecting the presence or absence of a gap between the first workpiece W10 and the first electrode 21, and the presence or absence of a gap between the second workpiece W20 and the second electrode 22, and determining the pressing amount when at least one gap is detected based on the value detected by the movement amount sensor 41.

[0104] Furthermore, this second setting value c may be set to a pressing amount less than the pressing amount determined by detecting whether or not a discharge phenomenon occurs between the first workpiece W10 and the first electrode 21, and whether or not a discharge phenomenon occurs between the second workpiece W20 and the second electrode 22, and determining the pressing amount when at least one of the discharge phenomena is detected by the value detected by the movement amount sensor 41.

[0105] (2) The solid-phase bonding apparatus 1 that performs the solid-phase bonding method described above is shown as having a configuration in which the second pressure shaft 12 of the first pressure shaft 11 is fixed and the first pressure shaft 11 is operated to push the pair of pressure shafts 11 and 12 into the first workpiece W10 and the second workpiece W20. However, the solid-phase bonding apparatus 1 that performs the solid-phase bonding method described above may also be configured to push the pair of pressure shafts 11 and 12 into the first workpiece W10 and the second workpiece W20 by operating both the first pressure shaft 11 and the second pressure shaft 12.

[0106] (3) In the embodiments described above, an example of a configuration was described in which the position of the first electrode 21 in the thickness direction of the first workpiece W10 is adjusted by the first adjustment device 14 and the first air cylinder 16. However, the solid-phase bonding apparatus 1 is not limited to this, and a configuration in which the position of the first electrode 21 in the thickness direction of the first workpiece W10 is adjusted by only the first air cylinder 16 without the first adjustment device 14 is also possible.

[0107] (4) In the embodiments described above, an example of a configuration was described in which the position of the second electrode 22 in the thickness direction of the second workpiece W20 is adjusted by the second adjustment device 15 and the second air cylinder 17. However, the solid-phase bonding apparatus 1 is not limited to this, and a configuration in which the position of the second electrode 22 in the thickness direction of the second workpiece W20 is adjusted by only the second air cylinder 17 without the second adjustment device 15 is also possible.

[0108] (5) In the embodiments described above, an example was shown in which air cylinders such as the first air cylinder 16 and the second air cylinder 17 were used to adjust the position of the pair of electrodes 21 and 22. However, the invention is not limited to this, and instead of air cylinders, a configuration may be used in which a servo motor is used to adjust the position of the pair of electrodes 21 and 22.

[0109] <Summary> (1) The solid-state bonding method of the present disclosure comprises the steps (steps S1 to S3) of pressing a first workpiece (first workpiece W10) and a second workpiece (second workpiece W20) that overlap in the thickness direction with a pair of pressure shafts (first pressure shaft 11, second pressure shaft 12) positioned on both sides in the thickness direction to form protrusions (protrusions 6, 7) on at least one of the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20), and while the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) are being pressed by the pair of pressure shafts (first pressure shaft 11, second pressure shaft 12), the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) are respectively positioned around the pair of pressure shafts (first pressure shaft 11, second pressure shaft 12) The method includes the steps of: starting to energize the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) from a pair of electrodes (first electrode 21, second electrode 22) in contact with (0) (step S4); and ending the energization by the pair of electrodes (first electrode 21, second electrode 22) when the amount of pressure applied by the pair of pressure shafts (first pressure shaft 11, second pressure shaft 12) in the thickness direction of the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) after the pressing by the pair of pressure shafts (first pressure shaft 11, second pressure shaft 12) has started and the pressing by the pair of pressure shafts (first pressure shaft 11, second pressure shaft 12) has reached a set value (step S8), while the pressing by the pair of pressure shafts (first pressure shaft 11, second pressure shaft 12) is continuing (steps S5 to S7, step S9).

[0110] With this configuration, in solid-phase bonding, when the first and second workpieces are pressed by a pair of pressure shafts and current is supplied to the first and second workpieces from a pair of electrodes, the current supplied by the pair of electrodes is terminated while the pressing by the pair of pressure shafts continues, in response to the amount of indentation by the pair of pressure shafts reaching a set value. In this way, since the current supplied by the pair of electrodes is terminated in response to the amount of indentation by the pair of pressure shafts reaching a set value, even if a gap is created between the first and second workpieces and the pair of electrodes due to deformation of the first and second workpieces thereafter, a discharge phenomenon can be prevented. Therefore, according to this disclosure, it is possible to prevent a discharge phenomenon caused by a gap between the first and second workpieces and the pair of electrodes, and to suppress a deterioration in the quality of the solid-phase bonding that may occur when current is supplied from the pair of electrodes to the first and second workpieces.

[0111] (2) In the solid-state bonding method of (1) above, the set value is set to the amount of indentation before a gap (gap 8, 9) is formed between at least one of the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) and the pair of electrodes, due to deformation of at least one of the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) in response to the pressing by the pair of pressurizing shafts (first pressurizing shaft 11, second pressurizing shaft 12) after the start of energization by the pair of electrodes (first electrode 21, second electrode 22).

[0112] With this configuration, the set value is set to the amount of indentation before a gap is formed between at least one of the first and second workpieces and the pair of electrodes due to deformation of at least one of the first and second workpieces, which can cause a discharge. Therefore, the discharge phenomenon caused by the gap between the first and second workpieces and the pair of electrodes can be reliably suppressed.

[0113] (3) In the solid-state bonding method of (2) above, the set value is set to a value of the amount of indentation within a range that does not hinder the softening of the bonding area between the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) due to the energization by the pair of electrodes (first electrode 21, second electrode 22), based on data measured in advance regarding the relationship between the amount of indentation of the pair of pressure shafts (first pressure shaft 11, second pressure shaft 12) and the presence or absence of discharge.

[0114] With this configuration, the set value is determined based on data obtained in advance from the relationship between the amount of pressure applied by the pair of pressurizing shafts and the presence or absence of discharge. The set value is determined to be within a range that does not hinder the softening of the bonding area between the first and second workpieces due to the energization by the pair of electrodes. Therefore, the discharge phenomenon caused by the gap between the first and second workpieces and the pair of electrodes can be reliably suppressed without affecting the softening of the bonding area in solid-state bonding.

[0115] (4) In any of the solid-state bonding methods described in (1) to (3) above, the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) are soft metals (aluminum, gold, silver, etc.).

[0116] With this configuration, when the first and second workpieces are made of soft metals, it is possible to suppress the discharge phenomenon caused by the gap between the first and second workpieces and the pair of electrodes.

[0117] (5) In the solid-state bonding method of (4) above, the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) are the same soft metal (aluminum, gold, silver, etc.).

[0118] With this configuration, when the first and second workpieces are made of the same soft metal, it is possible to suppress the discharge phenomenon caused by the gap between the first and second workpieces and the pair of electrodes.

[0119] (6) In the solid-state bonding method of (4) or (5) above, the soft metal includes aluminum (aluminum, aluminum alloy, gold, silver, etc.).

[0120] With this configuration, in soft metals such as aluminum, it is possible to suppress the discharge phenomenon caused by the gap between the first and second workpieces and the pair of electrodes.

[0121] (7) The solid-state bonding method of the present disclosure comprises a pair of pressurizing shafts (first pressurizing shaft 11, second pressurizing shaft 12) that press a first workpiece (first workpiece W10) and a second workpiece (second workpiece W20) that overlap in the thickness direction from both sides in the thickness direction, a pair of electrodes (first electrode 21, second electrode 22) respectively arranged around the pair of pressurizing shafts (first pressurizing shaft 11, second pressurizing shaft 12), and a control of the pair of pressurizing shafts (first pressurizing shaft 11, second pressurizing shaft 12) and the pair of electrodes (first electrode 21, second electrode 22) The device comprises a control device (control device 30) which presses the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) with the pair of pressurizing shafts (first pressurizing shaft 11, second pressurizing shaft 12) to form protrusions (protrusions 6, 7) on at least one of the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) (steps S1 to S3), and the pair of pressurizing shafts (first pressurizing shaft 11, second pressurizing shaft With the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) being pressed by 12), current is supplied to the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) from a pair of electrodes (first electrode 21, second electrode 22) that are in contact with the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) (step S4), and pressing by the pair of pressurizing shafts (first pressurizing shaft 11, second pressurizing shaft 12) is started. Then, when the amount of pressure applied by the pair of pressure shafts (first pressure shaft 11, second pressure shaft 12) in the thickness direction of the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) reaches a set value, the current is turned off by the pair of electrodes (first electrode 21, second electrode 22) while the pressing by the pair of pressure shafts (first pressure shaft 11, second pressure shaft 12) is continuing (steps S5 to S7, step S9) (step S8).

[0122] With this configuration, in solid-phase bonding, when the first and second workpieces are pressed by a pair of pressure shafts and current is supplied to the first and second workpieces from a pair of electrodes, the current supplied by the pair of electrodes is terminated while the pressing by the pair of pressure shafts continues, in response to the amount of indentation by the pair of pressure shafts reaching a set value. In this way, since the current supplied by the pair of electrodes is terminated in response to the amount of indentation by the pair of pressure shafts reaching a set value, even if a gap is created between the first and second workpieces and the pair of electrodes due to deformation of the first and second workpieces thereafter, a discharge phenomenon can be prevented. Therefore, according to this disclosure, it is possible to prevent a discharge phenomenon caused by a gap between the first and second workpieces and the pair of electrodes, and to suppress a deterioration in the quality of the solid-phase bonding that may occur when current is supplied from the pair of electrodes to the first and second workpieces.

[0123] (8) In the solid-phase bonding apparatus of (7) above, the set value is set to the amount of indentation before a gap (gap 8, 9) is formed between at least one of the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) and the pair of electrodes (first electrode 21, second electrode 22) due to deformation of at least one of the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) in response to the pressing by the pair of pressure shafts (first pressure shaft 11, second pressure shaft 12) after the start of energization by the pair of electrodes (first electrode 21, second electrode 22).

[0124] With this configuration, the set value is set to the amount of indentation before a gap is formed between at least one of the first and second workpieces and the pair of electrodes due to deformation of at least one of the first and second workpieces, which can cause a discharge. Therefore, the discharge phenomenon caused by the gap between the first and second workpieces and the pair of electrodes can be reliably suppressed.

[0125] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0126] W10 First workpiece, W20 Second workpiece, 11 First pressurizing shaft, 12 Second pressurizing shaft, 21 First electrode, 22 Second electrode, 1 Solid-phase bonding device, 6,7 Protrusions, 8,9 Gap, 30 Control device.

Claims

1. A step of forming a projection on at least one of the first and second workpieces by pressing the first and second workpieces, which overlap in the thickness direction, with a pair of pressure shafts positioned on both sides in the thickness direction, With the first workpiece and the second workpiece being pressed by the pair of pressurizing shafts, the step of starting to supply current to the first workpiece and the second workpiece from a pair of electrodes that are positioned around the pair of pressurizing shafts and are in contact with the first workpiece and the second workpiece, A solid-state bonding method comprising the step of terminating the energization by the pair of electrodes while the pressing by the pair of pressure shafts continues, in accordance with the amount of indentation by the pair of pressure shafts in the thickness direction of the first workpiece and the second workpiece since pressing by the pair of pressure shafts began, when the amount of indentation by the pair of pressure shafts in the thickness direction of the first workpiece and the second workpiece reaches a set value.

2. The solid-phase bonding method according to claim 1, wherein the set value is set to the amount of indentation before a gap is formed between at least one of the first workpiece and the second workpiece and the pair of electrodes due to deformation of at least one of the first workpiece and the second workpiece and the pair of electrodes, in response to the pressing by the pair of pressurizing shafts after the commencement of current flow by the pair of electrodes.

3. The solid-phase bonding method according to claim 2, wherein the setting value is set to a value of the amount of indentation within a range that does not hinder the softening of the bonding area between the first workpiece and the second workpiece due to the energization by the pair of electrodes, based on data measured in advance regarding the relationship between the amount of indentation of the pair of pressurizing shafts and the presence or absence of discharge.

4. The solid-phase bonding method according to claim 1 or claim 2, wherein the first workpiece and the second workpiece are made of a soft metal.

5. The solid-state bonding method according to claim 4, wherein the first workpiece and the second workpiece are the same soft metal.

6. The solid-phase bonding method according to claim 4, wherein the soft metal includes aluminum.

7. A pair of pressure shafts that press the first and second workpieces, which overlap in the thickness direction, from both sides in the thickness direction, A pair of electrodes are arranged around the pair of pressure shafts, The system comprises a control device for controlling the pair of pressurizing shafts and the pair of electrodes, The control device is By pressing the first workpiece and the second workpiece with the pair of pressure shafts, a protrusion is formed on at least one of the first workpiece and the second workpiece. With the first and second workpieces being pressed by the pair of pressurizing shafts, current is supplied to the first and second workpieces from a pair of electrodes in contact with the first and second workpieces. A solid-phase bonding apparatus that controls the energization of the pair of electrodes to be terminated while the pressing by the pair of pressure shafts continues, in accordance with the amount of indentation the pair of pressure shafts have made in the thickness direction of the first and second workpieces since the pressing by the pair of pressure shafts began, once the indentation amount has reached a set value.

8. The solid-phase bonding apparatus according to claim 7, wherein the set value is set to the amount of indentation before a gap is formed between at least one of the first workpiece and the second workpiece and the pair of electrodes due to deformation of at least one of the first workpiece and the second workpiece and the pair of electrodes, in response to the pressing by the pair of pressurizing shafts after the commencement of energization by the pair of electrodes.

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