Solid-state bonding apparatus and solid-state bonding system

Abstract

To enable appropriate positioning at a location where bonding failure does not occur in solid-state bonding.SOLUTION: A first pressurizing shaft 11 is movable relative to a second pressurizing shaft 12. After the first pressurizing shaft 11 is pressed into a first workpiece W10, a storage device 33 is further provided to store a load detected by a detection device and a displacement of the first pressurizing shaft 11 when the first pressurizing shaft 11 moves in a direction opposite to the pressing direction. A control device 30 determines, from the history of the displacement and load stored in the storage device 33, whether or not the first workpiece W10 and the second workpiece W20 have undergone plastic deformation.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a solid state bonding apparatus and a solid state bonding system including the solid state bonding apparatus. [Background technology]

[0002] Japanese Patent No. 7242112 (Patent Document 1) discloses a solid-state spot joining apparatus including a pressure mechanism including a pressing unit and an energization mechanism including a pair of welding electrodes. The solid-state spot joining apparatus disclosed in Japanese Patent No. 7242112 (Patent Document 1) is configured to energize two metal plates with a pair of welding electrodes to heat each metal plate, and then press the two metal plates together in a direction perpendicular to the metal plates using a pressing unit. When a joining method such as that disclosed in Japanese Patent No. 7242112 (Patent Document 1), which joins metals in a solid state at a low temperature without melting them (hereinafter also referred to as "solid-state joining"), is applied to a system equipped with a robot arm, positioning when starting the joining process is important to prevent poor joining.

[0003] Japanese Patent Laid-Open Publication No. 2008-307595 (Patent Document 2) discloses a method for positioning a spot welding robot. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7242112 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-307595 Summary of the Invention [Problem to be solved by the invention]

[0005] In Japanese Patent Laid-Open No. 2008-307595 (Patent Document 2), the current value of the servo motor that drives the movable electrode tip is monitored, and when the current value exceeds a predetermined value, the tip of the movable electrode tip is deemed to have come into contact with the workpiece, thereby achieving positioning. However, the electrode tip is subject to wear when current is passed through it. For this reason, the technology disclosed in Japanese Patent Laid-Open No. 2008-307595 (Patent Document 2) requires processing such as correction to ensure accurate positioning, making it difficult to properly position the electrode tip at a position that will not result in poor welding.

[0006] An object of the present disclosure is to provide a technique for appropriately positioning a part at a position that will not result in a poor bond during solid-state bonding. [Means for solving the problem]

[0007] The present disclosure relates to a solid-state joining apparatus for joining conductive first and second workpieces overlapping in a thickness direction in a solid state. The solid-state joining apparatus includes a pair of pressure shafts that press the first and second workpieces from both sides in the thickness direction, a pair of electrodes respectively arranged around the pair of pressure shafts, a control device, and a detection device that detects loads applied to the first and second workpieces. The pair of pressure shafts includes a first pressure shaft that presses the first workpiece and a second pressure shaft that presses the second workpiece. The first pressure shaft is movable relative to the second pressure shaft. The apparatus further includes a storage device that stores the displacement of the first pressure shaft when the first pressure shaft is pressed into the first workpiece and then moved in the direction opposite to the pressing direction, and the load detected by the detection device. The control device determines whether the first and second workpieces have undergone plastic deformation based on the history of displacements and loads stored in the storage device.

[0008] A solid-state welding system according to the present disclosure includes the above-described solid-state welding apparatus and a robot having a robot arm, and a control device that moves the robot arm to a first workpiece and a second workpiece and then presses the first pressurizing shaft into the first workpiece. [Effects of the Invention]

[0009] According to the present disclosure, the control device determines whether the first workpiece and the second workpiece have undergone plastic deformation based on the history of displacement and load stored in the storage device. By using such a determination result, it is possible to appropriately position the first workpiece and the second workpiece at positions that will not result in poor welding during solid-state welding. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram schematically showing a solid-state joining system according to a first embodiment. [Figure 2] 1 is a diagram schematically showing a solid-state joining apparatus according to a first embodiment. [Figure 3] FIG. 10 is a diagram for explaining a joining step. [Figure 4] FIG. 10 is a diagram for explaining a state in which positioning is correct. [Figure 5] FIG. 10 is a diagram for explaining a state in which positioning is incorrect. [Figure 6] 4 is a flowchart showing the control content executed by the control device. DETAILED DESCRIPTION OF THE INVENTION

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

[0012] [Embodiment 1] 1 is a diagram schematically illustrating a solid-state welding system 100 according to embodiment 1. The solid-state welding system 100 includes a robot 200, a solid-state welding apparatus 10, a control device 30, and a power supply device 35. Note that the robot 200 is illustrated smaller than the actual size of the solid-state welding apparatus 10.

[0013] The robot 200 includes a robot arm 210. The robot arm 210 is a multi-joint arm, for example, a six-axis multi-joint arm. The robot arm 210 is controlled by a control device 30 so as to execute a set operation. Note that the robot arm 210 may be configured to be controlled by a separate control device that controls the robot 200, rather than the control device 30.

[0014] The solid-state welding equipment 10 includes a driving device 13, a C-gun 14, and a pair of electrodes 21 and 22. The solid-state welding equipment 10 is attached to the tip of a robot arm 210. The driving of the driving device 13 is controlled by a control device 30. A voltage and current are supplied to the pair of electrodes 21 and 22 from a power supply device 35. The C-gun 14 is movable to a position where it sandwiches the first workpiece W10 and the second workpiece W20 fixed to a jig 60 in the thickness direction. The control device 30 controls a servo motor (not shown) to move the robot arm 210 to the first workpiece W10 and the second workpiece W20.

[0015] Next, the solid-state joining apparatus 1 according to the embodiment 1 will be specifically described. Fig. 2 is a diagram schematically showing the solid-state joining apparatus 1 according to the embodiment 1. The solid-state joining apparatus 1 is an apparatus that forms softened regions at the interfaces of the workpieces W10, W20 by passing an electric current through the workpieces W10, W20 that are stacked on top of each other, and then plastically deforms the softened regions to join the workpieces W10, W20 together in a solid state without melting them.

[0016] The multiple 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 a material other than metal, as long as it is electrically conductive and suitable for solid-state welding.

[0017] 2, the solid-state bonding apparatus 1 includes a solid-state bonding device 10, a control device 30, a power supply device 35, and a drive device 13. The solid-state bonding device 10 includes a pair of pressure shafts 11 and 12, a pair of electrodes 21 and 22, and a sensor 40.

[0018] The pair of pressure applying shafts 11, 12 includes a first pressure applying shaft 11 and a second pressure applying shaft 12. The pair of pressure applying shafts 11, 12 are capable of applying pressure to the first workpiece W10 and the second workpiece W20 from both sides in the thickness direction of the stacked plate-shaped workpieces. The first pressure applying shaft 11 is movably disposed at one end of the C gun 14 shown in FIG. 1 and is driven by a driving device 13. The second pressure applying shaft 12 is fixed to the other end of the C gun 14 shown in FIG. 1. The first pressure applying shaft 11 is movable relative to the second pressure applying shaft 12.

[0019] The first pressure shaft 11 is capable of pressing the first workpiece W10 so as to plastically deform the first workpiece W10. Specifically, the first pressure shaft 11 is capable of pressing the first workpiece W10 so as to form a protrusion W11 on the first workpiece W10. The first pressure shaft 11 is made of, for example, tungsten carbide. In this embodiment, the first pressure shaft 11 is formed in the shape of an elongated cylinder. The first pressure shaft 11 has a pressing surface 11a that presses the first workpiece W10. The pressing surface 11a is an end surface of the first pressure shaft 11. The pressing surface 11a is formed in a circular shape.

[0020] The second pressure applying shaft 12 has the same configuration as the first pressure applying shaft 11. The second pressure applying shaft 12 is disposed in such a position that the central axis of the second pressure applying shaft 12 is located on an extension of the central axis of the first pressure applying shaft 11, and the pressing surface 12a of the second pressure applying shaft 12 faces the pressing surface 11a of the first pressure applying shaft 11. Note that the first pressure applying shaft 11 and the second pressure applying shaft 12 may have a shape other than a cylindrical shape.

[0021] The sensor 40 is provided, for example, on the first pressure applying shaft 11. In this embodiment, a load cell is used as the sensor 40. The sensor 40 detects the load applied to the first pressure applying shaft 11. The load applied to the first pressure applying shaft 11 is also applied to the first workpiece W10 and the second workpiece W20. In other words, the sensor 40 functions as a detection device that detects the loads applied to the first workpiece W10 and the second workpiece W20. The location where the sensor 40 is installed is not limited to the first pressure applying shaft 11, and it may be installed on the drive device 13, etc.

[0022] The pair of electrodes 21, 22 includes a first electrode 21 and a second electrode 22. The pair of electrodes 21, 22 can pass electricity through the first workpiece W10 and the second workpiece W20 while in contact with the first workpiece W10 and the second workpiece W20. When a voltage is applied to the pair of electrodes 21, 22 while the pair of electrodes 21, 22 are in contact with the first workpiece W10 and the second workpiece W20, power is supplied to the first electrode 21, the first workpiece W10, the second workpiece W20, and the second electrode 22.

[0023] The first electrode 21 can come into contact with a portion of the first workpiece W10 surrounding the portion that is pressed by the first pressing shaft 11. In this embodiment, the first electrode 21 is formed in a cylindrical shape that surrounds 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 comes into contact with 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.

[0024] The second electrode 22 has the same configuration as the first electrode 21. The second electrode 22 can come into contact with a portion of the second workpiece W20 surrounding a portion that is pressed by the second pressure shaft 12. The second electrode 22 is disposed in such a position that the central axis of the second electrode 22 is located on an extension of the central axis of the first electrode 21, and the contact surface 22a of the second electrode 22 faces the contact surface 21a of the first electrode 21.

[0025] The control device 30 includes an arithmetic unit 31, a memory 32, a storage device 33, and an input / output interface 34. These components are connected via a bus.

[0026] The arithmetic device 31 is a computing entity (computer) that executes predetermined processing. The arithmetic device 31 is configured with a processor such as a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), a TPU (Tensor Processing Unit), or a GPU (Graphics Processing Unit). A processor, which is an example of the arithmetic device 31, has the function of executing predetermined processing by executing a predetermined program. However, some or all of these functions may be implemented using dedicated hardware circuits such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). The term "processor" is not limited to processors in the narrow sense that execute processing using a stored program, such as a CPU, MPU, TPU, or GPU, but may also include hardwired circuits such as an ASIC or FPGA. Furthermore, the arithmetic device 31 is not limited to von Neumann computers such as a CPU or GPU, but may also be configured with a non-von Neumann computer such as a quantum computer or an optical computer. The arithmetic device 31 described above may also be interpreted as a processing circuitry that executes predetermined processing. The computing device 31 may be configured as a single chip or multiple chips. Furthermore, the processor and related processing circuits may be configured as multiple computers interconnected by wire or wirelessly via a local area network or a wireless network. The processor and related processing circuits may be configured as a cloud computer that performs remote calculations based on input data and outputs the calculation results to other devices in remote locations.

[0027] 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 the memory 32 include volatile memories such as DRAM and SRAM, and non-volatile memories such as ROM and flash memory.

[0028] The storage device 33 stores various programs and various data executed by the arithmetic device 31. For example, the storage device 33 stores a control program 330 that controls various devices executed by the arithmetic device 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 the storage device 33 include a hard disk drive (HDD) and a solid state drive (SSD).

[0029] Values ​​acquired by an acquisition unit such as a sensor 40 are input to the input / output interface .

[0030] The control device 30 controls the drive device 13 to control the stroke of the first pressure shaft 11. The control device 30 controls the power supply device 35 to control the current supplied to the pair of electrodes 21, 22. Specifically, the control device 30 controls the drive device 13 to control the amount of depression of the pair of pressure shafts 11, 12 and the pair of electrodes 21, 22. Furthermore, the control device 30 controls the power supply device 35 to control the current X passed through the pair of electrodes 21, 22.

[0031] The control device 30 causes the drive device 13 to apply a load F (see FIG. 2) from the pair of pressure shafts 11, 12 to the first workpiece W10 and the second workpiece W20 so that protrusions W11, W21 that come into contact with each other are formed on the first workpiece W10 and the second workpiece W20, respectively. The control device 30 causes the power supply device 35 to apply electricity to the first workpiece W10 and the second workpiece W20. Specifically, the control device 30 controls the drive device 13 and the power supply device 35 to apply a load F to the first workpiece W10 and the second workpiece W20 from the pair of pressure shafts 11, 12, and to apply electricity to the first workpiece W10 and the second workpiece W20 while bringing the contact surface 21a of the first electrode 21 into contact with a portion of the first workpiece W10 surrounding a portion of the first workpiece W10 that is pressed by the first pressure shaft 11 and bringing the contact surface 22a of the second electrode 22 into contact with a portion of the second workpiece W20 surrounding a portion of the second workpiece W20 that is pressed by the second pressure shaft 12. The control device 30 controls the power supply device 35 so that a current X, indicated by a dashed line, flows between the pair of electrodes 21, 22 via the protrusions W11, W21.

[0032] Each of the protrusions W11, W21 is softened by passing a current X through them. In this embodiment, the control device 30 applies a load F to the first workpiece W10 and the second workpiece W20 by passing a current X through them to soften them and pressing the first pressure shaft 11 toward the second pressure shaft 12. This allows the first workpiece W10 and the second workpiece W20 to be joined while still in a low-temperature solid phase without changing their materials while applying a high pressure to the softened regions of each of the protrusions W11, W21 (regions including the contact interface between the workpieces W10 and W20).

[0033] Next, the joining process when positioning is performed correctly will be described. FIG. 3 is a diagram for explaining the joining process. The control device 30 performs the joining process in the order of FIGS. 3(A) to 3(E). As shown in FIG. 3(A), a pair of electrodes 21, 22 is fixed to a pair of pressure shafts 11, 12 by a spring 50. The biasing force of the spring 50 acts on each of the workpieces W10, W20 via the pair of electrodes 21, 22. The spring 50 is not shown in FIG. 3(B) and subsequent figures.

[0034] As shown in FIG. 3A, the control device 30 moves the robot arm 210 to a position to start joining the first workpiece W10 and the second workpiece W20. For example, the control device 30 moves the robot arm 210 to a position where the end of the second pressure shaft 12 contacts the second workpiece W20. Note that the ends of the pair of electrodes 21, 22 protrude toward the first workpiece W10 and the second workpiece W20 beyond the ends of the pair of pressure shafts 11, 12 when the first workpiece W10 and the second workpiece W20 are not being pressed. This allows the pair of electrodes 21, 22 to contact the first workpiece W10 and the second workpiece W20 before the pair of pressure shafts 11, 12 do, thereby allowing current to flow appropriately.

[0035] Next, the control device 30 moves the first pressure shaft 11 toward the first workpiece W10. As a result, as shown in FIG. 3B, the pair of electrodes 21, 22 contact the first workpiece W10 and the second workpiece W20, and the pair of pressure shafts 11, 12 contact the first workpiece W10 and the second workpiece W20. Here, when the first pressure shaft 11 is moved toward the first workpiece W10, incorrect positioning may result in the second pressure shaft 12 not contacting the second workpiece W20. The control device 30 moves the first pressure shaft 11 slightly toward the first workpiece W10 from the state shown in FIG. 3B, thereby performing a positioning determination to prevent poor welding. The positioning determination will be described later.

[0036] Next, if the control device 30 determines that the positioning has been performed correctly, it moves the first pressure shaft 11 toward the first workpiece W10 and applies a load to each of the workpieces W10 and W20 to form protrusions. By applying the load to each of the workpieces W10 and W20 to form protrusions, each of the protrusions W11 and W21 shown in FIG. 3(C) is formed.

[0037] Next, the control device 30 energizes each of the protrusions W11, W21 as shown in Fig. 3(D). The control device 30 energizes each of the protrusions W11, W21 formed at the contact portions of the workpieces W10, W20 to soften the contact portions of the protrusions W11, W21. Next, as shown in Fig. 3(E), the control device 30 presses the pair of pressure shafts 11, 12 to the joining position while energizing each of the protrusions W11, W21, thereby joining the workpieces W10, W20 at the contact portions.

[0038] To perform the bonding shown in FIG. 3, it is important that positioning is performed correctly when starting the bonding. Correct positioning means that the control device 30 moves the robot arm 210 to the correct position when starting the bonding process. If positioning is not performed correctly, the control device 30 determines the positioning using a simple method and adjusts the position of the robot arm 210 so that correct positioning is performed. Below, a specific description is given of a technique that can perform appropriate positioning at a position that does not result in a bond failure in solid-state bonding.

[0039] Fig. 4 is a diagram for explaining what happens when positioning is correct. Fig. 5 is a diagram for explaining what happens when positioning is incorrect. The control device 30 determines whether positioning has been performed correctly by slightly pressing the first pressure shaft 11 into the first workpiece W10.

[0040] 4(A) and 5(A) show the state when positioning determination is being performed with the jig 60 fixed to the first workpiece W10 and the second workpiece W20. Note that the pair of electrodes 21, 22 are not shown in FIGS. 4(A) and 5(A). FIGS. 4(B) and 5(B) show the relationship between the displacement of the first pressure shaft 11 and the load applied to the first pressure shaft 11 when positioning determination is performed. Note that the displacement of the first pressure shaft 11 may be obtained from the value of a sensor that detects the rotation angle of a servo motor (not shown). The displacement of the first pressure shaft 11 may also be detected by other detection methods. The displacement of the first pressure shaft 11 is transmitted from the sensor to the memory 32 or the storage device 33 and stored therein.

[0041] As shown in Figure 4(A), when positioning is performed correctly, the first workpiece W10 and the second workpiece W20 are pressed uniformly in the pressing direction by slightly pressing the first pressure shaft 11 from its initial position against the first workpiece W10. As shown in Figure 4(B), as the displacement of the first pressure shaft 11 increases from the origin of the reference position, the load applied to the first pressure shaft 11 also increases. Thereafter, pressure to the first pressure shaft 11 is stopped, and the first pressure shaft 11 is moved to its initial position.

[0042] As the first pressure applying shaft 11 moves, the load applied to the first workpiece W10 and the second workpiece W20 decreases, and the displacement also decreases. However, as shown in FIG. 4(B), the displacement does not become zero at the point when the load becomes zero. This is because the first workpiece W10 and the second workpiece W20 change shape from their original state due to plastic deformation, and the load applied to the first pressure applying shaft 11 becomes zero before the first pressure applying shaft 11 returns to its initial position. In FIG. 4(B), the area inside the curve enclosed by the displacement and load is the plastic work volume.

[0043] Next, as shown in FIG. 5(A), a case will be described in which positioning is not performed correctly and the workpiece is displaced from the reference position (position indicated by the dashed line). The first workpiece W10 is pressed by slightly pushing the first pressure shaft 11 from its initial position against the first workpiece W10. However, the second workpiece W20 is not pressed because the second pressure shaft 12 is not in contact with the second workpiece W20. As shown in FIG. 5(B), as the displacement of the first pressure shaft 11 increases from the origin of the reference position, the load applied to the first pressure shaft 11 also increases. Thereafter, pressure is stopped on the first pressure shaft 11, and the first pressure shaft 11 is moved to its initial position.

[0044] As the first pressure applying shaft 11 moves, the load applied to the first workpiece W10 and the second workpiece W20 decreases, and the displacement also decreases. Unlike the case of plastic deformation in Figure 4, the first workpiece W10 and the second workpiece W20 are elastically deformed and return to their original shapes. As a result, when the load applied to the first workpiece W10 and the second workpiece W20 becomes zero, the displacement of the first pressure applying shaft 11 also becomes zero.

[0045] After the first pressure shaft 11 is pressed into the first workpiece W10, the displacement of the first pressure shaft 11 when the first pressure shaft 11 moves in the direction opposite to the pressing direction (moves to the initial position) and the load detected by the sensor 40 are stored in the memory 32 or the storage device 33. The control device 30 determines whether the first workpiece W10 and the second workpiece W20 have been plastically deformed from the history of the displacement and load stored in the memory 32 or the storage device 33.

[0046] As shown in Fig. 4(B), when the first pressure applying shaft 11 is slightly pushed from its initial position into the first workpiece W10, the control device 30 determines that plastic deformation has occurred if the displacement becomes 0 before the first pressure applying shaft 11 returns to its initial position. As shown in Fig. 5(B), when the first pressure applying shaft 11 is slightly pushed from its initial position into the first workpiece W10, the control device 30 determines that plastic deformation has not occurred (elastic deformation has occurred) if the load becomes 0 when the first pressure applying shaft 11 returns to its initial position.

[0047] Next, the control contents executed by the control device 30 will be described. FIG. 6 is a flowchart showing the control contents executed by the control device 30. The processing of the flowchart in FIG. 6 is repeatedly called as a subroutine from the main routine in the control of the control device 30 and executed. First, in step S (hereinafter simply referred to as "S") 1, the control device 30 controls the robot arm 210 to move the pair of pressure shafts 11, 12 attached to the robot arm 210 toward the first workpiece W10 and the second workpiece W20. When the robot arm 210 is positioned at an appropriate position, the second pressure shaft 12 comes into contact with the second workpiece W20.

[0048] Next, the control device 30 controls the drive device 13 to move the movable first pressure shaft 11 toward a contact position where it comes into contact with the first workpiece W10 (S2). Next, the control device 30 determines whether the movable first pressure shaft 11 has come into contact with the first workpiece W10 (S3). The control device 30 determines that the first pressure shaft 11 has come into contact with the first workpiece W10 based on a change in the detection value of the sensor 40.

[0049] If the control device 30 determines that the first pressure applying shaft 11 is not in contact with the first workpiece W10 (NO in S3), it returns to the process of S2. If the control device 30 determines that the first pressure applying shaft 11 is in contact with the first workpiece W10 (YES in S3), it starts measuring the displacement and the load (S4). Specifically, the control device 30 stores the displacement and the load in the memory 32 or the storage device 33.

[0050] Next, the control device 30 controls the drive device 13 to slightly push the first pressure shaft 11 in the pressing direction (S5). Next, the control device 30 controls the drive device 13 to move the first pressure shaft 11 in the direction opposite to the pressing direction to the initial position (S6).

[0051] Next, the control device 30 determines whether the relationship between the displacement and the load stored in the memory 32 or the storage device 33 indicates plastic deformation (S7). In the processing of S7, the control device 30 determines whether the first workpiece W10 and the second workpiece W20 have undergone plastic deformation based on the history of the displacement and the load stored in the memory 32 or the storage device 33.

[0052] Specifically, the control device 30 determines that the first workpiece W10 and the second workpiece W20 have not been plastically deformed (have been elastically deformed) if the displacement is 0 at the timing when the load becomes 0 based on the history of displacement and load stored in the memory 32 or the storage device 33. The control device 30 determines that the first workpiece W10 and the second workpiece W20 have been plastically deformed if the displacement is not 0 at the timing when the load becomes 0 based on the history of displacement and load stored in the memory 32 or the storage device 33.

[0053] Next, if the control device 30 determines that the relationship between the displacement and the load stored in the memory 32 or the storage device 33 is plastic deformation (YES in S7), the process proceeds to S9. If the control device 30 determines that the relationship between the displacement and the load stored in the memory 32 or the storage device 33 is not plastic deformation (it is elastic deformation) (NO in S7), the process proceeds to S8. In the process of S8, the control device 30 controls the drive device 13 to change the positions of the pair of pressure shafts 11, 12 to positions where the first workpiece W10 and the second workpiece W20 are plastically deformed when pressed, and returns to the process of S5.

[0054] In the process of S9, the control device 30 executes the protrusion forming process as shown in FIG. 3(C). In the protrusion forming process, for example, the following control is executed. The control device 30 stores the position where the first pressure shaft 11 contacts the first workpiece W10 as a reference position. The control device 30 controls the drive device 13 to push the pair of pressure shafts 11, 12 to a preset protrusion forming position. This forms protrusions on the first workpiece W10 and the second workpiece W20.

[0055] Next, the control device 30 executes the joining process as shown in Figures 3(D) and (E) (S10), and returns the process from the subroutine to the main routine. In the joining process, for example, the following control is executed. The control device 30 controls the pair of electrodes 21, 22 to pass current for joining, while pushing the pair of pressure shafts 11, 12 to a preset joining push-in end position (joining position). This joins the first workpiece W10 and the second workpiece W20.

[0056] In the solid-state welding apparatus 1 of the first embodiment, the control device 30 determines whether the first workpiece W10 and the second workpiece W20 have undergone plastic deformation based on the history of displacements and loads stored in the memory 32 or the storage device 33. This allows the solid-state welding apparatus 1 to easily determine whether plastic deformation has occurred based on the history of displacements and loads stored in the memory 32 or the storage device 33, and to change the positions of the pair of pressure shafts 11, 12 if plastic deformation has not occurred. In this way, the solid-state welding apparatus 1 can use the determination result of whether plastic deformation has occurred to appropriately position the workpieces to positions that will not result in poor welding during solid-state welding.

[0057] <Summary> (1) The present disclosure relates to a solid-state joining apparatus 1 that joins, in a solid state, a first workpiece W10 and a second workpiece W20 that are electrically conductive and overlap each other in the thickness direction. The apparatus includes a pair of pressure shafts 11, 12 that press the first workpiece W10 and the second workpiece W20 from both sides in the thickness direction, a pair of electrodes 21, 22 that are respectively arranged around the pair of pressure shafts 11, 12, a control device 30, and a detection device (sensor 40) that detects the load applied to the first workpiece W10 and the second workpiece W20. The pair of pressure shafts 11, 12 includes a first pressure shaft 11 that presses the first workpiece W10 and a second pressure shaft 12 that presses the second workpiece W20. The first pressure shaft 11 is movable relative to the second pressure shaft 12. The control device 30 further includes a memory device 33 that stores the displacement of the first pressure shaft 11 and the load detected by the detection device (sensor 40) when the first pressure shaft 11 moves in the direction opposite to the pressing direction after being pressed into the first workpiece W10. The control device 30 determines whether the first workpiece W10 and the second workpiece W20 have been plastically deformed based on the history of the displacement and load stored in the memory device 33.

[0058] According to the solid-state welding apparatus 1 of the present disclosure, the control device 30 determines whether or not the first workpiece W10 and the second workpiece W20 have undergone plastic deformation based on the history of displacement and load stored in the storage device 33. This allows the solid-state welding apparatus 1 to appropriately position the workpieces W10 and W20 at positions that will not result in poor welding during solid-state welding, using the determination result of whether or not plastic deformation has occurred.

[0059] (2) In the solid-state joining apparatus 1 of (1), the control device 30 determines that the first workpiece W10 and the second workpiece W20 have not undergone plastic deformation when the displacement becomes 0 at the time when the load becomes 0, based on the history of displacement and load stored in the memory device 33.

[0060] According to the solid-state joining apparatus 1 of the present disclosure, it is possible to easily determine from the history of displacement and load stored in the storage device 33 that plastic deformation has not occurred.

[0061] (3) In the solid-state joining apparatus 1 of (1), the control device 30 determines that the first workpiece W10 and the second workpiece W20 have undergone plastic deformation when the displacement is not 0 at the time when the load becomes 0, based on the history of displacement and load stored in the memory device 33.

[0062] According to the solid-state joining apparatus 1 of the present disclosure, it is possible to easily determine whether plastic deformation has occurred from the history of displacement and load stored in the storage device 33.

[0063] (4) In the solid-state joining apparatus 1 of (2), the control device 30 changes the positions of the pair of pressure shafts 11, 12 when it determines that the first workpiece W10 and the second workpiece W20 are not plastically deformed.

[0064] According to the solid-state welding apparatus 1 of the present disclosure, when it is determined that no plastic deformation has occurred, the positions of the pair of pressure shafts 11, 12 can be changed to the correct positions.

[0065] (5) In the solid-state joining apparatus 1 of (3), when the control device 30 determines that the first workpiece W10 and the second workpiece W20 are plastically deformed, the control device 30 presses the first pressure shaft 11 against the first workpiece W10 so that a protrusion is formed at the contact point between the first workpiece W10 and the second workpiece W20.

[0066] According to the solid-state joining apparatus 1 of the present disclosure, if it is determined that plastic deformation has occurred, a protrusion for current flow can be formed, and therefore, if plastic deformation has not occurred, it is possible to prevent the process of forming the protrusion from proceeding.

[0067] (6) In any of the solid-state joining apparatuses 1 (1) to (5), the ends of the pair of electrodes 21, 22 protrude toward the first workpiece W10 and the second workpiece W20 beyond the ends of the pair of pressure shafts 11, 12 when the first workpiece W10 and the second workpiece W20 are not being pressed.

[0068] According to the solid-state joining apparatus 1 of the present disclosure, the ends of the pair of electrodes 21, 22 come into contact with the first workpiece W10 and the second workpiece W20 before the ends of the pair of pressure shafts 11, 12 come into contact with the first workpiece W10 and the second workpiece W20. This allows the pair of electrodes 21, 22 to come into contact with the first workpiece W10 and the second workpiece W20 before the pair of pressure shafts 11, 12 do, thereby allowing current to flow appropriately.

[0069] (7) In the solid-state welding apparatus 1 of any one of (1) to (6), the solid-state welding apparatus 1 is attached to the tip of a robot arm 210.

[0070] According to the solid-state welding apparatus 1 of the present disclosure, the result of determining whether or not plastic deformation has occurred during solid-state welding using the robot arm 210 can be used to appropriately position the workpiece at a position that will not result in poor welding.

[0071] (8) A solid-state joining system 100 of the present disclosure includes a solid-state joining apparatus 1 according to any one of (1) to (7) and a robot 200 having a robot arm 210. The control device 30 moves the robot arm 210 to the first workpiece W10 and the second workpiece W20, and then presses the first pressurizing shaft 11 into the first workpiece W10.

[0072] According to the solid-state joining system 100 of the present disclosure, by including the solid-state joining apparatus 1 and the robot 200 having the robot arm 210, it is possible to appropriately position the workpiece at a position that will not result in poor joining by using the determination result of whether or not plastic deformation has occurred during solid-state joining.

[0073] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0074] 1 solid-state joining device, 10 solid-state joining equipment, 11, 12 pressure shaft, 11a, 12a pressing surface, 13 drive unit, 14 C-gun, 21, 22 electrode, 21a, 22a contact surface, 30 control unit, 31 calculation unit, 32 memory, 33 storage device, 34 input / output interface, 35 power supply unit, 40 sensor, 50 spring, 60 jig, 100 solid-state joining system, 200 robot, 210 robot arm, 330 control program, W10, W20 workpiece, W11, W21 protrusion.

Claims

1. A solid-state joining apparatus for joining, in a solid state, a first workpiece and a second workpiece that are conductive and overlap each other in a thickness direction, comprising: a pair of pressure shafts that press the first workpiece and the second workpiece from both sides in a thickness direction; a pair of electrodes respectively disposed around the pair of pressure shafts; a control device; a detection device that detects a load applied to the first workpiece and the second workpiece, the pair of pressure applying shafts includes a first pressure applying shaft that applies pressure to the first workpiece and a second pressure applying shaft that applies pressure to the second workpiece, the first pressure applying shaft is movable relative to the second pressure applying shaft, a storage device configured to store a displacement of the first pressure shaft when the first pressure shaft moves in a direction opposite to the pressing direction after the first pressure shaft is pressed into the first workpiece and the load detected by the detection device; The control device determines whether or not the first workpiece and the second workpiece have undergone plastic deformation based on the history of the displacement and the load stored in the storage device.

2. 2. The solid-state joining apparatus according to claim 1, wherein the control device determines that the first workpiece and the second workpiece are not plastically deformed when the displacement is 0 at a timing when the load becomes 0 based on the history of the displacement and the load stored in the storage device.

3. 2. The solid-state joining apparatus according to claim 1, wherein the control device determines that the first workpiece and the second workpiece have undergone plastic deformation when the displacement is not 0 at the time the load becomes 0 based on the history of the displacement and the load stored in the storage device.

4. 3. The solid-state joining apparatus according to claim 2, wherein said control device changes positions of said pair of pressure shafts when it is determined that said first workpiece and said second workpiece are not plastically deformed.

5. 4. The solid-state joining apparatus according to claim 3, wherein, when the control device determines that the first workpiece and the second workpiece are plastically deformed, the control device presses the first pressure shaft against the first workpiece so that a protrusion is formed at a contact portion between the first workpiece and the second workpiece.

6. 6. The solid-state joining apparatus according to claim 1, wherein the ends of the pair of electrodes protrude toward the first workpiece and the second workpiece beyond the ends of the pair of pressure shafts when the first workpiece and the second workpiece are not being pressed.

7. The solid-state joining apparatus according to claim 1 , wherein the solid-state joining apparatus is attached to a tip of a robot arm.

8. The solid-state bonding apparatus according to claim 1 ; a robot having a robot arm, The control device moves the robot arm to the first workpiece and the second workpiece, and then presses the first pressure shaft into the first workpiece.

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