Solid-phase bonding device

Abstract

To provide an art capable of joining workpieces at constant joint strength in solid-phase bonding.SOLUTION: In a solid-phase bonding device, a control device performs joint control in which a power supply device and a drive device are operated to conduct a joint step in which a pair of pressurizing shafts presses a joint area between a first workpiece and a second workpiece for a predetermined period with the joint area softened by an initial current being applied by a pair of electrodes and flowing through the first workpiece and the second workpiece. Further, the control device calculates, based on a pressing load detected by a pressure sensor in the joint step, a rate of change of the pressing load and estimates, based on the rate of change of the pressing load obtained by the calculation, the pressing load at the conclusion of a predetermined elapsed time, and performs current control in which the power source device is operated so that a current value of the current to flow through the first workpiece and the second workpiece is increased or decreased according to a difference between a reference value of the pressing load at the conclusion of the predetermined elapsed time and an estimate value of the pressing load obtained by the estimation to adjust the pressing load at the conclusion of the predetermined elapsed time to the reference value (STEP S1 to S8).SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a solid-phase bonding device.

Background Art

[0002] Japanese Patent No. 7242112 (Patent Document 1) discloses a solid-phase point bonding device including a pressing mechanism including a pressing part and an energization mechanism including a pair of welding electrodes. In the solid-phase point bonding device disclosed in Patent Document 1, a constant current is passed from the electrodes to the bonding region of the workpiece to soften the bonding region, and the workpiece is pressed by the pressing part, whereby the workpiece is bonded.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional solid-phase bonding device, a constant current is passed through the bonding region of the workpiece to soften the bonding region. However, even when the same constant current is passed, the degree of softening of the bonding region may vary. In the conventional solid-phase bonding device, the pressure shaft is pushed into the workpiece by a certain amount without considering the degree of softening of the bonding region. Therefore, in the conventional solid-phase bonding device, if the degree of softening of the bonding region varies each time the workpiece is bonded, the range in which the softened portion spreads may vary each time the workpiece is bonded. The size of the range in which the softened portion spreads affects the bonding strength of the workpiece. For example, when the range in which the softened portion spreads is of an appropriate size, the bonding strength of the workpiece can be increased. Therefore, in the conventional solid-phase bonding device, it may be difficult to bond the workpiece with a constant bonding strength.

[0005] An object of the present disclosure is to provide a technique capable of bonding a workpiece with a constant bonding strength in solid-phase bonding.

Means for Solving the Problem

[0006] The solid-phase bonding device of the present disclosure includes a pair of pressing shafts that press a first workpiece and a second workpiece, which are conductive and overlap in the thickness direction, from both sides in the thickness direction, a pair of electrodes respectively arranged around the pair of pressing shafts, a driving device that drives the pair of pressing shafts, a power supply device that supplies power to the pair of electrodes, a sensor that detects the pressing load with which the pair of pressing shafts press the first workpiece and the second workpiece, and a control device that controls the driving device and the power supply device. The control device performs bonding control to operate the power supply device and the driving device so as to execute a bonding process in which an initial current is passed from the pair of electrodes to the first workpiece and the second workpiece to soften the bonding region between the first workpiece and the second workpiece, and the pair of pressing shafts press the bonding region for a predetermined period. Based on the pressing load detected by the sensor in the bonding process, the control device calculates the change rate of the pressing load, estimates the pressing load at the end of the predetermined period based on the change rate of the pressing load obtained by the calculation, and, according to the difference between the reference value of the pressing load at the end of the predetermined period and the estimated value of the pressing load obtained by the estimation, increases or decreases the current value of the current flowing through the first workpiece and the second workpiece, thereby performing current control to operate the power supply device so that the pressing load at the end of the predetermined period becomes the reference value.

Advantages of the Invention

[0007] According to the present disclosure, based on the pressing load detected by the sensor in the bonding process, the change rate of the pressing load is calculated, the pressing load at the end of the predetermined period is estimated based on the change rate of the pressing load obtained by the calculation, and, according to the difference between the reference value of the pressing load at the end of the predetermined period and the estimated value of the pressing load obtained by the estimation, the current value of the current flowing through the first workpiece and the second workpiece is increased or decreased, thereby operating the power supply device so that the pressing load at the end of the predetermined period becomes the reference value. Therefore, it is possible to adjust the degree of softening of the bonding region to be constant by the current value of the current flowing through the first workpiece and the second workpiece, and by making the range in which the softened portion spreads an appropriate size, the workpieces can be bonded with a certain bonding strength in solid-phase bonding.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0009] 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 denoted by the same reference numerals and their description will not be repeated.

[0010] [Embodiment 1] <Explanation of the Schematic Configuration of the Solid-Phase Bonding Apparatus 1> FIG. 1 is a diagram schematically showing a solid-phase bonding apparatus 1 according to Embodiment 1. The solid-phase bonding apparatus 1 forms a softening region as a bonding region at the interface of a plurality of workpieces W10 and W20 by energizing the plurality of workpieces W10 and W20 overlapped with each other, and plastically deforms the softening region to bond the plurality of workpieces W10 and W20 to each other in a solid state without melting.

[0011] The plurality of workpieces W10, W20 include a first workpiece W10 and a second workpiece W20. Each workpiece W10, W20 is made of a metal such as iron or aluminum. Each workpiece W10, W20 is formed, for example, in a flat plate shape. Note that each workpiece W10, W20 may be made of something other than metal, as long as it has conductivity and is a material suitable for solid-phase bonding.

[0012] As shown in FIG. 1, the solid-phase bonding apparatus 1 includes a solid-phase bonding device 10, a control device 30, a power supply device 35, a drive device 13, and an input device 5. The solid-phase bonding device 10 includes a pair of pressure shafts 11, 12, a pair of electrodes 21, 22, and a pressure sensor 40.

[0013] The pair of pressure shafts 11, 12 include a first pressure shaft 11 and a second pressure shaft 12. The pair of pressure shafts 11, 12 can apply pressure to both sides of the first workpiece W10 and the second workpiece W20 in the thickness direction with the plate-shaped workpieces stacked. The first pressure shaft 11 is driven by a first drive device 13. The second pressure shaft 12 is fixed. The first pressure shaft 11 is movable relative to the second pressure shaft 12.

[0014] The first pressure shaft 11 can press the first workpiece W10 so that the first workpiece W10 undergoes plastic deformation. 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 the present embodiment, the first pressure shaft 11 is formed in an elongated columnar shape. The first pressure shaft 11 has a pressing surface 11a for pressing 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.

[0015] The second pressure shaft 12 has the same configuration as that of the first pressure shaft 11. The central axis of the second pressure shaft 12 is located on the extension line of the central axis of the first pressure shaft 11, and the pressing surface 12a of the second pressure shaft 12 is arranged in a posture facing the pressing surface 11a of the first pressure shaft 11. Note that the first pressure shaft 11 and the second pressure shaft 12 may have a shape other than a columnar shape.

[0016] The second pressing shaft 12 is arranged such that the central axis of the second pressing shaft 12 is located on the extension line of the central axis of the first pressing shaft 11, and the pressing surface 120 of the second pressing shaft 12 faces the pressing surface 110 of the first pressing shaft 11. Note that the first pressing shaft 11 and the second pressing shaft 12 may have shapes other than cylindrical shapes.

[0017] The pressure sensor 40 is provided, for example, on the first pressing shaft 11. In this embodiment, a load cell is used as the pressure sensor 40. Note that the installation location of the pressure sensor 40 is not limited to the first pressing shaft 11, and it may be provided on the drive device 13 or the like.

[0018] The pair of electrodes 21, 22 includes a first electrode 21 and a second electrode 22. The pair of electrodes 21, 22 can be energized to 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. When a voltage is applied to the pair of electrodes 21, 22 in a state where the pair of electrodes 21, 22 is in contact with the first workpiece W10 and the second workpiece W20, electric power is supplied to the first electrode 21, the first workpiece W10, the second workpiece W20, and the second electrode 22.

[0019] The first electrode 21 can contact a portion around the portion of the first workpiece W10 that is pressed by the first pressing shaft 11. In this embodiment, the first electrode 21 is formed in a cylindrical shape surrounding the first pressing shaft 11. A gap is provided between the inner peripheral surface of the first electrode 21 and the outer peripheral surface of the first pressing 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. Note that the shape of the contact surface 21a is not limited to an annular shape.

[0020] The second electrode 22 has the same configuration as that of the first electrode 21. The second electrode 22 can contact a portion around the portion of the second workpiece W20 that is pressed by the second pressing shaft 12. The second electrode 22 is arranged such that the central axis of the second electrode 22 is located on the extension line 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.

[0021] The control device 30 includes an arithmetic device 31, a memory 32, a storage device 33, and an input / output interface 34. These components are connected via a bus.

[0022] The arithmetic unit 31 is an arithmetic entity (computer) that executes predetermined processing. The arithmetic unit 31 is composed of, for example, a processor such as a CPU (Central Processing Unit), MPU (Micro-Processing Unit), TPU (Tensor Processing Unit), or GPU (Graphics Processing Unit). Note that a processor, which is an example of the arithmetic unit 31, has a function of executing predetermined processing by executing a predetermined program, but some or all of these functions may be implemented using a dedicated hardware circuit such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array). The "processor" is not limited to a narrow sense processor that executes processing in a stored-program manner like a CPU, MPU, TPU, or GPU, and may include a hardwired circuit such as an ASIC or FPGA. Also, the arithmetic unit 31 is not limited to a Neumann type computer such as a CPU or GPU, and may be composed of a non-Neumann type computer such as a quantum computer or an optical computer. The arithmetic unit 31 as described above can also be read as a processing circuit (Processing Circuitry) that executes predetermined processing. Note that the arithmetic unit 31 may be composed of one chip or a plurality of chips. Furthermore, the processor and related processing circuits may be composed of a plurality of computers interconnected by wire or wirelessly via a local area network or a wireless network. The processor and related processing circuits may be composed of a cloud computer that remotely performs arithmetic operations based on input data and outputs the arithmetic operation results to other devices located at a remote location.

[0023] Memory 32 includes a storage area (e.g., a working area) that stores program codes or a work memory when the arithmetic unit 31 executes various programs. Examples of the memory 32 include volatile memories such as DRAM and SRAM, or non-volatile memories such as ROM and flash memory.

[0024] The storage device 33 stores various programs or various data executed by the arithmetic unit 31. For example, the storage device 33 stores a control program 330 that controls various devices executed by the arithmetic unit 31. The storage device 33 may be one or more non-transitory computer readable media, or may be one or more computer readable storage media. Examples of the storage device 33 include HDD (Hard Disk Drive) and SSD (Solid State Drive).

[0025] Data detected by a sensor such as a pressure sensor 40, for example, is input to the input / output interface 34. An input device 5 is connected to the control device 30. The input device 5 is composed of one or more devices among devices capable of inputting data such as a keyboard, a mouse, and a touch panel. The data input from the input device can be input to the arithmetic unit 31 and the memory 32 via the input / output interface 34.

[0026] The control device 30 controls the stroke of the first pressing shaft 11 by controlling the drive device 13. The control device 30 controls the supply current to the pair of electrodes 21 and 22 by controlling the power supply device 35. Specifically, the control device 30 controls the drive device 13 and moves the first pressing shaft 11 toward the first workpiece W10, thereby applying loads acting on the first workpiece W10 and the second workpiece W20 from each of the pair of pressing shafts 11 and 12, loads acting on the first workpiece W10 and the second workpiece W20 from each of the pair of electrodes 21 and 22, and the pushing-in amounts of the pair of pressing shafts 11 and 12 and the pair of electrodes 21 and 22. Further, the control device 30 controls the power supply device 35 and controls the current X supplied to the pair of electrodes 21 and 22.

[0027] The control device 30 causes the drive device 13 to perform an operation of applying a load F to the first workpiece W10 and the second workpiece W20 from the pair of pressing shafts 11 and 12 so that protrusions W11 and W21 that contact each other are formed on each of the first workpiece W10 and the second workpiece W20. The control device 30 causes the power supply device 35 to perform an operation of energizing the first workpiece W10 and the second workpiece W20. Specifically, by the control device 30 controlling the drive device 13 and the power supply device 35, the following state is produced.

[0028] An operation of energizing the first workpiece W10 and the second workpiece W20 is performed in a state where a load F is applied to the first workpiece W10 and the second workpiece W20 from the pair of pressing shafts 11 and 12, and the contact surface 21a of the first electrode 21 is brought into contact with a portion around the portion of the first workpiece W10 that is pressed by the first pressing shaft 11, and the contact surface 22a of the second electrode 22 is brought into contact with a portion around the portion of the second workpiece W20 that is pressed by the second pressing shaft 12. The control device 30 controls the power supply device 35 so that a current X indicated by a broken line flows between the pair of electrodes 21 and 22 through the respective protrusions W11 and W21. Each of the protrusions W11 and W21 softens when the current X flows therethrough.

[0029] In this embodiment, the control device 30 causes a current X to flow to soften each of the protrusions W11 and W21, and pushes the first pressing shaft 11 toward the first workpiece W10 and the second pressing shaft 12 toward the second workpiece W20, thereby applying a load F in a direction opposite to the first workpiece W10 and the second workpiece W20. As a result, in this embodiment, the first workpiece W10 and the second workpiece W20 can be joined at the positions of the protrusions W11 and W21.

[0030] <Description of the protrusion forming step and the joining step> Next, the flow of processing in the protrusion forming step and the joining step executed in the solid-phase joining device 1 will be described. In the solid-phase joining device 1, when joining the first workpiece W10 and the second workpiece W20, after executing the protrusion forming step, the joining step is executed.

[0031] In the protrusion forming step, the control device 30 executes the following control. The control device 30 moves the first pressing shaft 11 on the movable side to a contact position where it contacts the first workpiece W10. Next, the control device 30 stores, as a reference position, the position where the first pressing shaft 11 contacts the first workpiece W10. The control device 30 controls the drive device 13 to push the pair of pressing shafts 11 and 12 to a preset protrusion forming position. As a result, protrusions are formed on the first workpiece W10 and the second workpiece W20.

[0032] In the joining step, the control device 30 executes the following control. The control device 30 controls the pair of electrodes 21 and 22 to perform energization for joining, and pushes the pair of pressing shafts 11 and 12 to a preset joining push end position (joining position). As a result, the first workpiece W10 and the second workpiece W20 are joined.

[0033] <Description of changes in the pressing load in the protrusion forming step and the joining step> FIG. 2 is a diagram showing changes in the pressing load during the protrusion forming process and the joining process. In FIG. 2, the vertical axis represents the pressing load with which a pair of pressing shafts 11 and 12 press the first workpiece W10 and the second workpiece W20, and the horizontal axis represents the elapsed time, showing the state of changes in the pressing load during the protrusion forming process and the joining process.

[0034] Referring to FIG. 2, the changes in the pressing load during the protrusion forming process and the joining process will be described below. When the protrusion forming process and the joining process are executed, first, in the protrusion forming process, the pair of pressing shafts 11 and 12 are pushed in by a predetermined pushing amount, so that the pressing load increases over time. Then, after the protrusion W11 is formed on the first workpiece W10 and the protrusion W12 is formed on the second workpiece W20, the pair of pressing shafts 11 and 12 move to a position where the load states of the protrusions W11 and W21 are appropriate for applying the joining current. When the pair of pressing shafts 11 and 12 move to such a position, the pressing load decreases over time. In the state where the protrusions W11 and 12 are formed, the pressing load becomes the first peak 71.

[0035] Subsequently, in the joining process, while flowing a current X through the protrusions W11 and W21, which are the joining regions of the first workpiece W10 and the second workpiece W20, to soften the protrusions W11 and W21, the pair of pressing shafts 11 and 12 are pushed in by a predetermined pushing amount, so that the pressing load increases over time. Then, after the first workpiece W10 and the second workpiece W20 are joined, the pair of pressing shafts 11 and 12 are returned to the position before being pushed in. When the pair of pressing shafts 11 and 12 are returned to the position before being pushed in, the pressing load decreases over time. In the state where the first workpiece W10 and the second workpiece W20 are joined, the pressing load becomes the second peak 72.

[0036] <Explanation of the relationship between the peak value of the pressing load and the amount of heat input> FIG. 3 is a diagram showing the relationship between the peak values of the pressing load (first peak 71 and second peak 72) described above and the amount of heat input by the current X in the first workpiece W10 and the second workpiece W20. In FIG. 3, the peak value of the pressing load is taken on the vertical axis, and the amount of heat input is taken on the horizontal axis, and these relationships are shown.

[0037] Referring to FIG. 3, the relationship between the peak value of the pressing load and the amount of heat input will be described below. As the amount of heat input increases, the softening of the first workpiece W10 and the second workpiece W20 progresses, and the peak value of the pressing load decreases. The reason is that as the first workpiece W10 and the second workpiece W20 pressed by the pair of pressing shafts 11 and 12 become softer, it becomes difficult for the pressing load to increase. When the amount of heat input exceeds a specific value, the peak value of the pressing load corresponding to the amount of heat input saturates and becomes a constant value.

[0038] As shown in FIG. 3, within the range where the peak value of the pressing load decreases as the amount of heat input increases, for example, within the range of the peak values P1 to P2 of the pressing load corresponding to a predetermined range of the amount of heat input as shown by the amount of heat input H1 to H2, the joining strength between the first workpiece W10 and the second workpiece W20 becomes the highest. The reason is that the range in which the softened portion spreads is of an appropriate size, so that the joining strength between the first workpiece W10 and the second workpiece W20 becomes the highest. Therefore, in the joining process, it is necessary to set a reference value of the pressing load so that the peak value of the pressing load at the second peak 72 as shown in FIG. 2 is within the range of the peak values P1 to P2 where the joining strength is the highest as shown in FIG. 3, and the control device 30 controls so that the pressing load becomes the reference value.

[0039] <Description of current control for adjusting the pressing load in the joining process> Next, the current control for adjusting the pressing load in the joining process executed by the solid-phase joining device 1 will be described. In the joining process, in order to make the joining strength between the first workpiece W10 and the second workpiece W20 the highest, the control device 30 performs the following control.

[0040] FIG. 4 is a diagram for explaining current control for adjusting the pressing load in the joining process. In FIG. 4(A), the relationship between the change rate of the pressing load and the elapsed time in the joining process is shown. In FIG. 4(B), the relationship between the pressing load and the elapsed time in the protrusion formation process and the joining process is shown. In FIG. 4(C), the relationship between the current X and the elapsed time in the joining process is shown.

[0041] In the joining process, as shown in FIG. 4(B), after executing the protrusion formation process in which the pressing load becomes the first peak 71 shown in FIG. 2, the control device 30 executes control to push the pair of pressing shafts 11, 12 into the first workpiece W10 and the second workpiece W20 so that the pressing load becomes the second peak 72 shown in FIG. 2.

[0042] Specifically, in the joining process, the control device 30 executes control to flow the current X through the first workpiece W10 and the second workpiece W20 in a predetermined period from the first timing T1 to the third timing T3 as shown in FIG. 4(B), and at the same time, in the predetermined period from the first timing T1 to the third timing T3, executes control to push the pair of pressing shafts 11, 12 into the first workpiece W10 and the second workpiece W20 by a predetermined pushing amount. Thereby, the first workpiece W10 and the second workpiece W20 are joined in the joining process.

[0043] More specifically, the control device 30 executes the following control in the joining process. The control device 30 executes control to operate the power supply device 35 so that the current X can become the current I1 from the first timing T1. In the following description, the current I1 may be referred to as the initial current I1. Basically, the control device 30, in a predetermined period from the first timing T1 to the third timing T3 shown in FIG. 4(B), when the first workpiece W10 and the second workpiece W20 heated by the current I1 are softened, executes control to push the pair of pressing shafts 11, 12 so that the change rate of the pressing load becomes the reference change rate 60 indicated by the dashed-dotted line in FIG. 4(A).

[0044] When such control is executed, the pressing load increases in a reference change pattern 80 indicated by the dashed-dotted line in FIG. 4(B) during a predetermined period from the first timing T1 to the third timing T3, and the pressing load becomes the second peak 72. The pressing load of the second peak 72 is a reference value P3 of the pressing load set so as to be within the range of the peak values P1 to P2 where the bonding strength is the highest as shown in FIG. 3. The reference value P3 may be a value corresponding to the range of the peak values P1 to P2 shown in FIG. 2, and includes the case where it is set to one value and the case where it is set to a value indicated within a specific range. In the bonding process, when the pressing load becomes the reference value P3 after a lapse of the predetermined period from the first timing T1 to the third timing T3, the bonding strength between the first workpiece W10 and the second workpiece W20 becomes the highest.

[0045] However, in the bonding process, when the degree of softening of the first workpiece W10 and the second workpiece W20 due to the current I1 is less than expected, the pressing load P4 at the third timing T3 becomes higher than the reference value P3, as in the pressing load excess pattern 81 indicated by the broken line in FIG. 4(B). On the other hand, although not shown, in the bonding process, when the degree of softening of the workpiece W10 and the second workpiece W20 due to the current I1 is excessive compared to the assumption, the pressing load at the third timing T3 becomes lower than the reference value P3.

[0046] As described above, in the bonding process, when the degree of softening of the first workpiece W10 and the second workpiece W20 due to the current I1 is less than expected and when the degree of softening of the workpiece W10 and the second workpiece W20 due to the current I1 is excessive compared to the assumption, the bonding strength is lower than the case where the pressing load becomes the reference value P3 at the third timing T3.

[0047] In the control device 30, when the degree of softening of the first workpiece W10 and the second workpiece W20 due to the current I1 is less than expected and when it is excessive compared to the assumption, the current X is controlled as follows so that the pressing load becomes the reference value P3.

[0048] In the control device 30, data on the pressing load detected by the pressure sensor 40 is acquired from the first timing T1 in accordance with the passage of time. Then, in the control device 30, based on the data of a plurality of pressing loads detected by the pressure sensor 40 during the period from the first timing T1 to the second timing T2 after the first timing T1 has elapsed, the rate of change of the pressing load during the period from the first timing T1 to the second timing T2 is obtained by calculation.

[0049] The second timing T2 is a timing after the first timing T1 has elapsed, and when the current X is changed at the second timing T2, it is a timing such that the pressing load can change to the reference value P3 by the time the third timing T3 is reached.

[0050] In the control device 30, based on the current (second timing T2) pressing load detected by the pressure sensor 40 and the rate of change of the pressing load obtained by calculation, the pressing load at the end of a predetermined period from the first timing T1 to the third timing T3 is estimated. Such estimation of the pressing load is performed, for example, by multiplying the time difference from the second timing T2 to the third timing T3 by the rate of change of the pressing load to obtain the increase value of the pressing load between the second timing T2 and the third timing T3. Then, by adding the obtained increase value of the pressing load to the detected value of the current (second timing T2) pressing load, an estimated value of the pressing load at the end of the predetermined period from the first timing T1 to the third timing T3 can be obtained.

[0051] When the estimated value of the pressing load at the end of the predetermined period from the first timing T1 to the third timing T3 is obtained, in the control device 30, the obtained estimated value of the pressing load is compared with the aforementioned reference value P3.

[0052] In the control device 30, when the estimated value of the pressing load is different from the reference value P3 of the pressing load, the current value of the current X flowing through the first workpiece W10 and the second workpiece W20 is increased or decreased according to the difference between the estimated value of the pressing load and the reference value P3 of the pressing load, so that the pressing load at the end of a predetermined period becomes the reference value P3, and current control is performed to operate the power supply device 35.

[0053] In the control device 30, when the estimated value of the pressing load is higher than the reference value P3, such as the pressing load P4 in FIG. 4(B) for example, it means that the degree of softening of the first workpiece W10 and the second workpiece W20 by the initial current I1 is insufficient compared to the assumption. Therefore, current control is performed to make the current value of the current X higher than the initial current I1 so that the pressing load at the third timing T3 becomes the reference value P3.

[0054] Specifically, when the estimated value of the pressing load is higher than the reference value P3, such as the pressing load P4 in FIG. 4(B) for example, the control device 30 controls the power supply device 35 so that the current X changes to a current I2 higher than the initial current I1 according to the difference between the estimated value of the pressing load and the reference value P3 of the pressing load, as shown in FIG. 4(C). When such control is executed, since the degree of softening of the first workpiece W10 and the second workpiece W20 increases over time as the current X increases from the initial current I1, it becomes possible to make the pressing load at the end of the predetermined period from the first timing T1 to the third timing T3 become the reference value P3.

[0055] In the control device 30, when the estimated value of the pressing load is lower than the reference value P3, it means that the degree of softening of the first workpiece W10 and the second workpiece W20 by the initial current I1 is excessive compared to the assumption. Therefore, current control is performed to make the current value of the current X lower than the initial current I1 so that the pressing load at the third timing T3 becomes the reference value P3.

[0056] Specifically, when the estimated value of the pressing load is lower than the reference value P3, the control device 30 controls the power supply device 35 so that the current X changes to a current lower than the initial current I1 shown in FIG. 4(C) according to the difference between the estimated value of the pressing load and the reference value P3 of the pressing load. When such control is executed, since the degree of softening of the first workpiece W10 and the second workpiece W20 decreases over time as the current X decreases from the initial current I1, it becomes possible to make the pressing load at the end of a predetermined period from the first timing T1 to the third timing T3 become the reference value P3.

[0057] As control for increasing or decreasing the current value of the current X flowing through the first workpiece W10 and the second workpiece W20 according to the difference between the estimated value of the pressing load and the reference value of the pressing load, the control device 30 may perform control using the following data. For example, in the memory 32, a data table showing the relationship between the difference between the estimated value of the pressing load and the reference value of the pressing load and the increase or decrease value of the current X such that the pressing load converges to the reference value P3 during the period from the second timing T2 to the third timing T3 is stored. When a difference occurs between the estimated value of the pressing load and the reference value of the pressing load, the control device 30 refers to the data table and selects the increase or decrease value of the current X corresponding to the difference between the estimated value of the pressing load and the reference value of the pressing load. Then, the control device 30 performs control to increase or decrease the current value of the current X according to the increase or decrease value thus selected.

[0058] As described above, by the control device 30 executing current control for adjusting the pressing load in the bonding process, it is possible to make the pressing load at the end of a predetermined period from the first timing T1 to the third timing T3 become the reference value P3 in the bonding process. Thereby, the bonding strength between the first workpiece W10 and the second workpiece W20 can be increased in the bonding process.

[0059] <Explanation of the flow of current control in the bonding process according to Embodiment 1> Next, the flow of current control in the bonding process executed by the control device 30 will be described. FIG. 5 is a flowchart showing the flow of current control in the bonding process according to the first embodiment.

[0060] The processing of the flowchart shown in FIG. 5 is a part of the control program read out and executed by the arithmetic unit 31 from the memory 32, and shows a program for executing the current control as described above in the bonding process.

[0061] In the arithmetic unit 31, in step S1, it is determined whether the current timing has become a first timing such as the first timing T1 shown in FIG. 4(B) in the bonding process. In the arithmetic unit 31, when it is determined in step S1 that the first timing T1 has been reached, until it is determined in step S3 that the second timing such as the second timing T2 shown in FIG. 4(B) has been reached, in step S2, data on the pressing load detected by the pressure sensor 40 is acquired according to the passage of time.

[0062] In the arithmetic unit 31, in step S3, it is determined whether the current timing has become the above-described second timing in the bonding process. In the arithmetic unit 31, when it is determined in step S3 that the second timing has been reached, in step S4, based on the detection data of the pressing load detected by the pressure sensor 40 and acquired in step S2 during the period from the above-described first timing to the second timing, the change rate of the pressing load during the period from the first timing to the second timing is obtained by calculation.

[0063] In the arithmetic unit 31, in step S5, based on the current pressing load (second timing T2) detected by the pressure sensor 40 and the change rate of the pressing load obtained by the calculation in step S4, the pressing load at the end of a predetermined period such as the period from the first timing T1 to the third timing T3 shown in FIG. 4(B) is estimated.

[0064] In the arithmetic unit 31, in step S6, it is determined whether the estimated value of the pressing load is higher than the reference value of the pressing load, such as the reference value P3 shown in FIG. 4(B) for example. When it is determined in step S6 that the estimated value of the pressing load is higher than the reference value of the pressing load, the arithmetic unit 31, in step S7, executes control to increase the current value of the current X from the current current value so that the pressing load at the time of elapse of the aforementioned predetermined period becomes the aforementioned reference value of the pressing load. Specifically, in step S6, the control device 30 executes control to operate the power supply device 35 so that the current value of the current X increases from the current current value.

[0065] On the other hand, when it is determined in step S6 that the estimated value of the pressing load is not higher than the reference value of the pressing load, the arithmetic unit 31, in step S8, determines whether the estimated value of the pressing load is lower than the reference value of the pressing load, such as the reference value P3 shown in FIG. 4(B) for example. When it is determined in step S8 that the estimated value of the pressing load is lower than the reference value of the pressing load, the arithmetic unit 31, in step S9, executes control to decrease the current value of the current X from the current current value so that the pressing load at the time of elapse of the aforementioned predetermined period becomes the aforementioned reference value of the pressing load. Specifically, in step S9, the control device 30 executes control to operate the power supply device 35 so that the current value of the current X decreases from the current current value.

[0066] The processes shown in steps S1 to S9 shown in FIG. 5 are repeatedly executed in the joining process as a subroutine called by the main routine of the control program executed by the arithmetic unit 31, whereby the current control shown in FIG. 4 is executed during the period in which the joining process is executed.

[0067] [Embodiment 2] In Embodiment 2, an example will be described in which when the control device 30 performs current control as described in Embodiment 1, the increase / decrease amount of the current value is adjusted based on the material characteristics of the first workpiece WO10 and the second workpiece WO20.

[0068] First, among the characteristics of the materials of the first workpiece WO10 and the second workpiece WO20, the characteristics related to current control will be described.

[0069] When the pushing-in amounts of the pair of pressing shafts 11 and 12 are constant, as the hardness of the first workpiece WO10 and the second workpiece WO20 increases, the deformation amounts of the first workpiece W10 and the second workpiece WO20 tend to decrease. Such a tendency is called the first characteristic. When the pushing-in amounts of the pair of pressing shafts 11 and 12 are constant, as the plate thickness of the first workpiece WO10 and the second workpiece WO20 increases, the deformation amounts of the first workpiece W10 and the second workpiece WO20 tend to decrease. Such a tendency is called the second characteristic. When the pushing-in amounts of the pair of pressing shafts 11 and 12 are constant, as the tensile strength of the first workpiece WO10 and the second workpiece WO20 increases, the deformation amounts of the first workpiece W10 and the second workpiece WO20 tend to decrease. Such a tendency is called the third characteristic.

[0070] Thus, when the deformation amounts of the first workpiece W10 and the second workpiece WO20 are different according to the characteristics of the materials, the control device 30 may perform control to adjust the increase and decrease amounts of the current value based on the characteristics of the materials of the first workpiece WO10 and the second workpiece WO20. By performing such control, the control device 30 can realize current control such that the pressing load at the end of a predetermined period becomes the reference value P3 according to the characteristics of the materials of the first workpiece WO10 and the second workpiece WO20.

[0071] Specifically, as the deformation amount of the material for a constant pushing-in amount of the pair of pressing shafts 11 and 12 decreases, the control device 30 performs control to increase the current value of the current X used for increasing and decreasing the current value in current control from the reference current value, and as the deformation amount of the material for a constant pushing-in amount of the pair of pressing shafts 11 and 12 increases, the control device 30 performs control to decrease the current value of the current X used for increasing and decreasing the current value in current control from the reference current value. By doing so, current control can be realized such that the pressing load at the end of a predetermined period becomes the reference value P3 according to the characteristics of the materials.

[0072] In the control device 30, in the joining process, a database for adjusting the current value of the current X according to the characteristics of the material is stored in the memory 32 for each type of material. The database for adjusting the current value of the current X is a database that determines the adjustment value of the current value with respect to the reference current value from the data on the hardness, plate thickness, and tensile strength of the materials of the respective workpieces in the first workpiece W10 and the second workpiece W20, taking into account all of the above-described first characteristic, second characteristic, and third characteristic so that the pressing load at the elapse of a predetermined period becomes the reference value P3. Such a reference current value is not particularly determined based on the characteristics of the material, but is predetermined based on a material having average characteristics among a plurality of types of materials that may be used as the first workpiece W10 and the second workpiece WO20, for example.

[0073] In the solid-phase joining device 1, when performing solid-phase joining, data on the type of the material of the workpiece and data on the plate thickness of the material of the workpiece are input from the input device 5 by the operator. These data are stored in the memory 32.

[0074] In the control device 30, when data on the type of the material and data on the plate thickness of the material are input from the input device 5, the arithmetic unit 31 reads out the data on the type of the material of the input workpiece and the data on the plate thickness of the materials of the first workpiece W10 and the second workpiece W20 from the memory 32, and selects a database corresponding to the input data on the type of the material from among a plurality of databases stored in the memory 32 for each type of material.

[0075] In the arithmetic unit 31, using the database selected according to the data of the type of material input from the input device 5, based on the data of the plate thickness input from the input device 5, the data of the hardness of the material stored in advance corresponding to the input type of material, and the data of the tensile strength of the material stored in advance corresponding to the input type of material, an adjustment value of the current value in current control is determined, and the determined adjustment value of the current value is stored in the memory 32. Such an adjustment value of the current value is set to a value used to adjust the increase or decrease of the reference current value, with the current value used in steps S7 and S9 of FIG. 5 as the reference current value.

[0076] FIG. 6 is a flowchart showing the flow of current control in the bonding process according to Embodiment 2.

[0077] The difference between the current control in the bonding process according to Embodiment 2 shown in FIG. 6 and the current control in the bonding process according to Embodiment 1 shown in FIG. 5 lies in steps S7A and S9A. Step S7A shown in FIG. 6 is executed instead of step S7 shown in FIG. 5. Step S9A shown in FIG. 6 is executed instead of step S9 shown in FIG. 6.

[0078] In the control device 30, in step S7A, when executing control to increase the current value of current X so that the pressing load at the elapse of the aforementioned predetermined period becomes the reference value P3 of the aforementioned pressing load, the current value adjusted according to the material characteristics of the first workpiece W10 and the second workpiece W20 is increased. Specifically, in step S7A, the reference current value used for increasing the current value in step S7 of FIG. 5 is adjusted by the adjustment value of the current value determined according to the material characteristics input from the input device 5 as described above for the currently executing bonding process, and current X is increased with the adjusted current value.

[0079] In the control device 30, in step S9A, when executing control to decrease the current value of current X so that the pressing load at the elapse of the aforementioned predetermined period becomes the reference value P3 of the aforementioned pressing load, the current value adjusted according to the characteristics of the materials of the first workpiece W10 and the second workpiece W20 is decreased. Specifically, in step S9A, the reference current value used for decreasing the current value in step S9 of FIG. 5 is adjusted by the adjustment value of the current value determined according to the characteristics of the material input from the input device 5 as described above for the currently executing bonding process, and current X is decreased with the adjusted current value.

[0080] As shown in FIG. 6, in the second embodiment, when the control device 30 performs current control as described in the first embodiment, by adjusting the increase or decrease amount of the current value based on the characteristics of the materials of the first workpiece WO10 and the second workpiece WO20, current control can be realized such that the pressing load at the elapse of a predetermined period becomes the reference value P3 according to the characteristics of the material.

[0081] <Description of Modification Example> (1) The solid-phase bonding device 1 shown in the above-described first and second embodiments is an example in which when the estimated value of the pressing load is different from the reference value in current control, the control device 30 changes the current flowing through the first workpiece WO10 and the second workpiece WO20 to a current higher or lower than the initial current I1. However, not limited to this, when the estimated value of the pressing load is different from the reference value, the control device 30 may perform control to change the current flowing through the first workpiece WO10 and the second workpiece WO20 to a current having a different energization pattern such as a pulse current having a current value different from the initial current I1 when changing to a current higher or lower than the initial current I1. In this way, in addition to the degree of softening of the first workpiece WO10 and the second workpiece WO20, since the energization pattern of the current to be changed is different from the initial current I1, it becomes possible to change the final composition of the bonding region of the first workpiece WO10 and the second workpiece WO20, and thereby it becomes possible to increase the bonding strength between the first workpiece WO10 and the second workpiece WO20.

[0082] (2) In the foregoing embodiment, an example was shown in which only the first pressing shaft 11 is driven by the driving device 13 when the first pressing shaft 11 and the second pressing shaft 12 are pressed into the first workpiece WO10 and the second workpiece WO20. However, the present invention is not limited to this, and both the first pressing shaft 11 and the second pressing shaft 12 may be driven by the driving device 13.

[0083] (3) In the foregoing Embodiment 2, an example was shown in which data regarding the type of the material of the workpiece and data regarding the plate thickness of the material of the workpiece are input from the input device 5. However, the present invention is not limited to this, and as the data input from the input device 5, in addition to the data regarding the plate thickness of the material of the workpiece, either one of the data regarding the hardness of the material of the workpiece and the data regarding the tensile strength of the material of the workpiece, or both data may be further input. In that case, a database that determines the adjustment amount of the current based on the input data regarding the hardness of the material of the workpiece, the input data regarding the plate thickness of the material of the workpiece, and the input data regarding the tensile strength of the material of the workpiece may be used.

[0084] (4) In the foregoing Embodiment 2, an example was shown in which data such as data regarding the type of the material of the workpiece and data regarding the plate thickness of the material of the workpiece are input from the input device 5 by an operator in order to adjust the current value in current control. However, the present invention is not limited to this, and the data used to adjust the current value, such as the data regarding the type of the material of the workpiece and the data regarding the plate thickness of the material of the workpiece, may be input by data communication from another computer provided inside or outside the solid-phase bonding device 1.

[0085] <Description of the Effects of the Embodiment> In the embodiment described above, the following effects can be obtained.

[0086] (1) As shown in FIGS. 4 to 6, the control device 30 allows an initial current I1 to flow from the pair of electrodes 21 and 22 to the first workpiece W10 and the second workpiece W20), softening the joint region (the region of the protrusions W11 and W21) between the first workpiece W10 and the second workpiece W20), while the pair of pressing shafts 11 and 12 presses the joint region (the region of the protrusions W11 and W21) for a predetermined period. Joint control is performed to operate the power supply device 35 and the drive device 13. Based on the pressing load detected by the pressure sensor 40 in the joint process, the rate of change of the pressing load is calculated (step S4). Based on the rate of change of the pressing load obtained by the calculation, the pressing load at the end of the predetermined period is estimated (step S5). According to the difference between the reference value of the pressing load at the end of the predetermined period and the estimated value of the pressing load obtained by the estimation, the current value of the current flowing through the first workpiece W10 and the second workpiece W20) is increased or decreased to operate the power supply device 35 so that the pressing load at the end of the predetermined period becomes the reference value (steps S6 to S9). As a result, the control device 30 calculates the rate of change of the pressing load based on the pressing load detected by the pressure sensor 40 in the joint process, estimates the pressing load at the end of the predetermined period based on the rate of change of the pressing load obtained by the calculation, and according to the difference between the reference value of the pressing load at the end of the predetermined period and the estimated value of the pressing load obtained by the estimation, the current value of the current flowing through the first workpiece W10 and the second workpiece W20) is increased or decreased to operate the power supply device 35 so that the pressing load at the end of the predetermined period becomes the reference value. Therefore, it is possible to adjust the degree of softening of the joint region to be constant by the current value of the current flowing through the first workpiece W10 and the second workpiece W20), and the workpieces can be joined with a constant joining strength in the solid-phase joining.

[0087] (2) As shown in FIGS. 4 to 6, when the estimated value of the pressing load is higher than the reference value in current control, the control device 30 operates the power supply device 35 so that the current value of the current flowing through the first workpiece W10 and the second workpiece W20 increases from the current current value. In current control, when the estimated value of the pressing load is lower than the reference value, the control device 30 operates the power supply device 35 so that the current value of the current flowing through the first workpiece W10 and the second workpiece W20 decreases from the current current value. Therefore, the power supply device 35 can be specifically operated so that the pressing load at the end of a predetermined period becomes the reference value.

[0088] (3) As shown in FIGS. 4 to 6, the control device 30 calculates the change rate of the pressing load based on the pressing load detected by the pressure sensor 40 during the period from the first timing T1 to the second timing T2 in the bonding process. Therefore, the current control for making the pressing load by the control device 30 become the reference value can be completed by the end of a predetermined period.

[0089] (4) As shown in FIGS. 4 to 6, the control device 30 estimates the pressing load at the end of a predetermined period based on the current pressing load detected by the pressure sensor 40 and the change rate of the pressing load obtained by calculation. Therefore, the pressing load at the end of a predetermined period can be accurately estimated according to the actual change state of the pressing load in the bonding process.

[0090] (5) As shown in FIG. 6, when the control device 30 performs current control, it adjusts the increase or decrease amount of the current value based on the material characteristics of the first workpiece W10 and the second workpiece W20). Therefore, the pressing load at the end of a predetermined period can be accurately estimated according to the actual change state of the pressing load in the bonding process.

[0091] <Summary> (1) The solid-phase bonding device (solid-phase bonding device 1) of the present disclosure includes a pair of pressing shafts (first pressing shaft 11, second pressing shaft 12) that press a first workpiece (first workpiece W10) and a second workpiece (second workpiece W20) that are conductive and 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 pressing shafts, a driving device (driving device 13) that drives the pair of pressing shafts, a power supply device (power supply device 35) that supplies power to the pair of electrodes (first electrode 21, second electrode 22), a sensor (pressure sensor 40) that detects the pressing load with which the pair of pressing shafts (first pressing shaft 11, second pressing shaft 12) press the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20), and a control device (control device 30) that controls the driving device (driving device 13) and the power supply device (power supply device 35). The control device (control device 30) softens the bonding region (region of protrusions W11, W21) between the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) by flowing an initial current from the pair of electrodes to the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20), and performs a bonding process in which the pair of pressing shafts (first pressing shaft 11, second pressing shaft 12) press the bonding region (region of protrusions W11, W21) for a predetermined period. The control device performs bonding control to operate the power supply device (power supply device 35) and the driving device (driving device 13). Based on the pressing load detected by the sensor (pressure sensor 40) in the bonding process, the change rate of the pressing load is calculated (step S4). Based on the change rate of the pressing load obtained by the calculation, the pressing load at the end of the predetermined period is estimated (step S5). According to the difference between the reference value of the pressing load at the end of the predetermined period and the estimated value of the pressing load obtained by the estimation, the current value of the current flowing through the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) is increased or decreased, and current control is performed to operate the power supply device (power supply device 35) so that the pressing load at the end of the predetermined period becomes the reference value (steps S6 to S9).

[0092] According to such a configuration, the control device calculates the rate of change of the pressing load based on the pressing load detected by the sensor in the joining process, estimates the pressing load at the end of a predetermined period based on the calculated rate of change of the pressing load, and increases or decreases the current value of the current flowing through the first workpiece and the second workpiece according to the difference between the reference value of the pressing load at the end of the predetermined period and the estimated value of the pressing load obtained by estimation, so as to operate the power supply device such that the pressing load at the end of the predetermined period becomes the reference value. Therefore, it is possible to adjust the softening degree of the joining region to be constant by the current value of the current flowing through the first workpiece and the second workpiece, and by making the range in which the softened portion spreads an appropriate size, the workpieces can be joined with a certain joining strength in solid-phase joining.

[0093] (2) In the solid-phase joining device (solid-phase joining device 1) of (1) above, in the current control, when the estimated value of the pressing load is higher than the reference value, the control device (control device 30) operates the power supply device (power supply device 35) so that the current value of the current flowing through the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) increases from the current current value. In the current control, when the estimated value of the pressing load is lower than the reference value, the control device operates the power supply device so that the current value of the current flowing through the first workpiece and the second workpiece decreases from the current current value (FIGS. 4(A) to (C)).

[0094] According to such a configuration, in the current control, when the estimated value of the pressing load is higher than the reference value, the control device operates the power supply device so that the current value of the current flowing through the first workpiece and the second workpiece increases from the current current value. In the current control, when the estimated value of the pressing load is lower than the reference value, the control device operates the power supply device so that the current value of the current flowing through the first workpiece and the second workpiece decreases from the current current value. Therefore, the power supply device can be specifically operated so that the pressing load at the end of the predetermined period becomes the reference value.

[0095] (3) In the solid-phase bonding device ((1) or (2), i.e., solid-phase bonding device 1), the control device (control device 30) calculates the rate of change of the pressing load based on the pressing load detected by the sensor (pressure sensor 40) during the period from the first timing (first timing T1) in the bonding process to the second timing (second timing T2) when the current control starts after the elapse of the first timing (first timing T1) (step S4).

[0096] According to such a configuration, the control device calculates the rate of change of the pressing load based on the pressing load detected by the sensor during the period from the first timing in the bonding process to the second timing when the current control starts after the elapse of the first timing. Therefore, the current control for making the pressing load by the control device become the reference value can be completed by the time a predetermined period elapses.

[0097] (4) In any one of the solid-phase bonding devices ((1) to (3), i.e., solid-phase bonding device 1), the control device (control device 30) estimates the pressing load at the time when the predetermined period has elapsed based on the current pressing load detected by the sensor (pressure sensor 40) and the rate of change of the pressing load obtained by the calculation (step S5).

[0098] According to such a configuration, since the control device estimates the pressing load at the time when the predetermined period has elapsed based on the current pressing load detected by the sensor and the rate of change of the pressing load obtained by the calculation, the pressing load at the time when the predetermined period has elapsed can be accurately estimated according to the actual change state of the pressing load in the bonding process.

[0099] (5) In any one of the solid-phase bonding devices ((1) to (4), i.e., solid-phase bonding device 1), when performing the current control, the control device (control device 30) adjusts the increase or decrease amount of the current value based on the material characteristics of the first workpiece (first workpiece W10) and the second workpiece (second workpiece W20) (steps S7A, S9A).

[0100] According to such a configuration, when the control device performs current control, it adjusts the increase or decrease amount of the current value based on the material characteristics of the first workpiece and the second workpiece. Therefore, according to the material characteristics of the first workpiece and the second workpiece, the pressing load at the end of a predetermined period can be made to be the reference value.

[0101] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is shown not by the description of the above embodiments but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0102] 1 Solid-phase bonding device, W10 First workpiece, W20 Second workpiece, 11 First pressing shaft, 12 Second pressing shaft, 21 First electrode, 22 Second electrode, 13 Driving device, 35 Power supply device, 40 Pressure sensor, 30 Control device, T1 First timing, T2 Second timing.

Claims

1. A pair of pressing shafts that are conductive and 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 respectively disposed around the pair of pressing shafts, A driving device that drives the pair of pressing shafts, A power supply device that supplies power to the pair of electrodes, A sensor that detects a pressing load with which the pair of pressing shafts press the first workpiece and the second workpiece, A control device that controls the driving device and the power supply device, The control device, While softening the joint region between the first workpiece and the second workpiece by flowing an initial current from the pair of electrodes to the first workpiece and the second workpiece, the pair of pressing shafts perform a joining process of pressing the joint region over a predetermined period. The joining control is performed to operate the power supply device and the driving device so as to perform the joining process, Based on the pressing load detected by the sensor in the joining process, the change rate of the pressing load is calculated, Based on the change rate of the pressing load obtained by the calculation, the pressing load at the end of the predetermined period is estimated, A solid-phase joining device that performs current control to operate the power supply device so that the pressing load at the end of the predetermined period becomes the reference value by increasing or decreasing the current value of the current flowing through the first workpiece and the second workpiece according to the difference between the reference value of the pressing load at the end of the predetermined period and the estimated value of the pressing load obtained by the estimation.

2. The control device, In the current control, when the estimated value of the pressing load is higher than the reference value, the power supply device is operated so that the current value of the current flowing through the first workpiece and the second workpiece increases from the current current value, The solid-phase joining device according to claim 1, wherein in the current control, when the estimated value of the pressing load is lower than the reference value, the power supply device is operated so that the current value of the current flowing through the first workpiece and the second workpiece decreases from the current current value.

3. The control device calculates the change rate of the pressing load based on the pressing load detected by the sensor in the period from the first timing in the joining process to the second timing when the current control is started after the elapse of the first timing. The solid-phase joining device according to claim 1 or claim 2.

4. The control device according to claim 1 or claim 2 estimates the pressing load at the end of the predetermined period based on the current pressing load detected by the sensor and the rate of change of the pressing load obtained by the calculation.

5. The control device according to claim 1 or claim 2 adjusts the increase or decrease amount of the current value based on the material characteristics of the first workpiece and the second workpiece when performing the current control.

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