Solid-phase bonding apparatus and estimation method

Abstract

The hardness of the first and second workpieces is estimated by utilizing the joining process. [Solution] The control device 30 presses the first workpiece W10 and the second workpiece W20 with a pair of pressurizing shafts 11 and 12 to form protrusions, and then further presses the pair of pressurizing shafts 11 and 12 while supplying power to a pair of electrodes 21 and 22 to join the first workpiece W10 and the second workpiece W20 in a solid state. Based on the first reaction force detected by the detection device 40 during the formation of the protrusions, the hardness is estimated using the data.

Description

TECHNICAL FIELD

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

BACKGROUND ART

[0002] Japanese Patent No. 7242112 (Patent Document 1) discloses a solid-phase spot joining apparatus including a pressurizing mechanism having a pressing portion and an energization mechanism having a pair of electrodes. The solid-phase spot joining apparatus disclosed in Japanese Patent No. 7242112 (Patent Document 1) is configured to press two metal plates composed of a first workpiece and a second workpiece in a direction orthogonal to the metal plates by the pressing portion in a state where the two metal plates are energized and heated by the pair of electrodes. A joining method for joining metals in a solid-phase state in a low temperature range without melting the metals as disclosed in Japanese Patent No. 7242112 (Patent Document 1) is also referred to as solid-phase joining hereinafter.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0003]

PATENT DOCUMENT 1

SUMMARY OF INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] The pressing portion is composed of, for example, a pair of pressurizing shafts. In solid-phase joining, after the first workpiece and the second workpiece are pressed by the pair of pressurizing shafts to form protrusions, the pair of pressurizing shafts are further pressed while power is supplied to the pair of electrodes, whereby the first workpiece and the second workpiece are joined in a solid-phase state. It is known that when the same high-hardness material is used for the first workpiece and the second workpiece, a high load is applied to the pair of pressurizing shafts during pressurization.

[0005] If a pair of pressure shafts break due to high load, problems such as downtime required for replacement and poor quality of the joint will occur. Furthermore, replacing the pair of pressure shafts prematurely will result in problems in terms of usable time and cost. Additionally, if the hardness of the first and second workpieces needs to be measured separately, unnecessary work time will be incurred. Therefore, it is conceivable that the above problems can be solved by estimating the hardness of the first and second workpieces using the joining process.

[0006] The purpose of this disclosure is to estimate the hardness of the first and second workpieces by utilizing the joining process. [Means for solving the problem]

[0007] This disclosure relates to a solid-state bonding apparatus for joining a first workpiece and a second workpiece that are conductive and overlap in the thickness direction in a solid state. The solid-state bonding apparatus comprises a pair of pressure shafts that press the first workpiece and the second workpiece from both sides in the thickness direction, a pair of electrodes arranged around the pair of pressure shafts, a detection device that detects the reaction force when the first workpiece and the second workpiece are pressed, a storage device that stores data showing the relationship between the reaction force and the hardness of the first workpiece and the second workpiece, and a control device. The control device presses the first workpiece and the second workpiece with the pair of pressure shafts to form protrusions, and then further presses the pair of pressure shafts while supplying power to the pair of electrodes to join the first workpiece and the second workpiece in a solid state, and estimates the hardness using data based on the first reaction force detected by the detection device during the formation of the protrusions. [Effects of the Invention]

[0008] According to this disclosure, the hardness can be estimated using data based on a first reaction force detected by a detection device during the formation of a protrusion, thereby utilizing the joining process to estimate the hardness of the first and second workpieces. [Brief explanation of the drawing]

[0009] [Figure 1]This diagram schematically shows a solid-phase bonding apparatus according to Embodiment 1. [Figure 2] This is a diagram illustrating the joining process. [Figure 3] This figure shows how various parameters change over time. [Figure 4] This diagram shows the relationship between the materials used for multiple workpieces, the indentation speed, and the reaction force. [Figure 5] This diagram illustrates the data used to control the control device. [Figure 6] This diagram provides a simplified explanation of the calculations performed by the control device. [Figure 7] This flowchart shows the control actions performed by the control device. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0011] [Embodiment 1] Figure 1 is a schematic diagram showing a solid-state bonding apparatus 1 according to Embodiment 1. The solid-state bonding apparatus 1 is a device that bonds multiple workpieces W10 and W20 that are stacked on top of each other, by applying an electric current to form softened regions at the interfaces of the multiple workpieces W10 and W20, and then plastically deforming these softened regions, thereby bonding the multiple workpieces W10 and W20 together in a solid state without melting them.

[0012] Multiple workpieces W10 and W20 include a first workpiece W10 and a second workpiece W20. Each workpiece W10 and W20 is made of a metal such as iron or aluminum. Each workpiece W10 and W20 is formed, for example, in a flat plate shape. However, each workpiece W10 and W20 may be made of a material other than metal, as long as it is conductive and suitable for solid-state bonding.

[0013] As shown in Figure 1, the solid-phase bonding apparatus 1 comprises a solid-phase bonding device 10, a control device 30, a power supply device 60, and a display device 70. The solid-phase bonding device 10 comprises a pair of pressure shafts 11 and 12, a pair of electrodes 21 and 22, a detection device 40, and actuators 15 and 25. The "pressure shafts" may also be referred to as "pressure members" or "pressing members."

[0014] The pair of pressurizing shafts 11 and 12 include a first pressurizing shaft 11 and a second pressurizing shaft 12. The pair of pressurizing shafts 11 and 12 can apply pressure to the first workpiece W10 and the second workpiece W20 from both sides in the thickness direction when the plate-shaped workpieces are stacked. The first pressurizing shaft 11 is driven by an actuator 15 as a drive source. The second pressurizing shaft 12 is driven by an actuator 25 as a drive source. The second pressurizing shaft 12 may be fixed instead of being driven by a drive source. In this way, one of the pair of pressurizing shafts 11 and 12 can be a fixed shaft.

[0015] The first press shaft 11 is capable of pressing the first workpiece W10 so that the first workpiece W10 undergoes plastic deformation. Specifically, the first press shaft 11 is capable of pressing the first workpiece W10 so that a projection W11 is formed on the first workpiece W10. The first press shaft 11 is made of, for example, tungsten carbide. In this embodiment, the first press shaft 11 is formed in a cylindrical shape. The first press shaft 11 has a pressing surface 11a that presses the first workpiece W10. The pressing surface 11a is the end face of the first press shaft 11. The pressing surface 11a is formed in a circular shape.

[0016] The second pressure shaft 12 has the same configuration as the first pressure shaft 11. The central axis of the second pressure shaft 12 is located on the extension of the central axis of the first pressure shaft 11, and the pressing surface 12a of the second pressure shaft 12 is positioned to face 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 shapes other than cylindrical.

[0017] The detection device 40 is provided, for example, in the actuator 15. In the present embodiment, a load cell is used as the detection device 40. Note that the installation location of the detection device 40 is not limited to the actuator 15. The detection device 40 may be installed in the other actuator 25, or may be installed in both the actuators 15 and 25. The detection device 40 may be provided on the first pressurizing shaft 11 or the second pressurizing shaft 12.

[0018] The pair of electrodes 21 and 22 includes a first electrode 21 and a second electrode 22. The pair of electrodes 21 and 22 can energize the first workpiece W10 and the second workpiece W20 while being in contact with the first workpiece W10 and the second workpiece W20. With the pair of electrodes 21 and 22 in contact with the first workpiece W10 and the second workpiece W20, a voltage is applied to the pair of electrodes 21 and 22, so that 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 of the first workpiece W10 around the portion pressurized by the first pressurizing shaft 11. In the present embodiment, the first electrode 21 is formed in a cylindrical shape surrounding the first pressurizing shaft 11. A gap is provided between the inner peripheral surface of the first electrode 21 and the outer peripheral surface of the first pressurizing shaft 11. The first electrode 21 is made of, for example, copper. The first electrode 21 has a contact surface 21a that comes into contact with 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 of the second workpiece W20 around the portion pressurized by the second pressurizing shaft 12. The second electrode 22 is arranged in a posture where 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 comprises an arithmetic unit 31, a memory 32, a storage device 33, and an input / output interface 34. These components are connected via a bus.

[0022] The arithmetic unit 31 is a computing entity (computer) that performs predetermined processing. The arithmetic unit 31 is composed of a processor such as a CPU (Central Processing Unit), MPU (Micro-Processing Unit), TPU (Tensor Processing Unit), or GPU (Graphics Processing Unit). While a processor, as an example of the arithmetic unit 31, has the function of performing predetermined processing by executing a predetermined program, some or all of these functions may be implemented using dedicated hardware circuits such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array). The term "processor" is not limited to processors in the narrow sense that execute processing using a stored-program method, such as a CPU, MPU, TPU, or GPU, but may also include hardwired circuits such as ASICs or FPGAs. Furthermore, the arithmetic unit 31 is not limited to von Neumann type computers such as CPUs or GPUs, but may also consist of non-von Neumann type computers such as quantum computers or optical computers. The arithmetic unit 31 described above can also be read as a processing circuitry that performs predetermined processing. The arithmetic unit 31 may consist of one chip or multiple chips. Furthermore, the processor and associated processing circuits may consist of multiple computers interconnected by wired or wireless connections via a local area network or wireless network. The processor and associated processing circuits may also consist of a cloud computer that remotely performs calculations based on input data and outputs the calculation results to other devices located at a distance.

[0023] The memory 32 includes a storage area (for example, a working area) for storing program code or work memory when the arithmetic unit 31 executes various programs. Examples of memory 32 include volatile memory such as DRAM and SRAM, or non-volatile memory such as ROM and flash memory.

[0024] The storage device 33 stores various programs or data executed by the arithmetic unit 31. For example, the storage device 33 stores a control program 330 that controls a pair of pressurizing shafts 11, 12 and a pair of electrodes 21, 22, which are executed by the arithmetic unit 31. The storage device 33 may be one or more non-transitory computer-readable media or one or more computer-readable storage media. Examples of storage devices 33 include HDDs (Hard Disk Drives) and SSDs (Solid State Drives).

[0025] The input / output interface 34 receives values ​​acquired by an acquisition unit such as the detection device 40. The display device 70 is connected to the input / output interface 34. The display device 70 displays various information based on commands from the control device 30.

[0026] The control device 30 controls a pair of pressurizing shafts 11, 12 and a pair of electrodes 21, 22. Specifically, the control device 30 controls the load acting on the first workpiece W10 and the second workpiece W20 from each of the pair of pressurizing shafts 11, 12, the load acting on the first workpiece W10 and the second workpiece W20 from each of the pair of electrodes 21, 22, the voltage applied to the pair of electrodes 21, 22, and the amount of pressure applied to the pair of pressurizing shafts 11, 12 and the pair of electrodes 21, 22. The control device 30 controls the current X supplied to the pair of electrodes 21, 22 by controlling the voltage applied to the pair of electrodes 21, 22.

[0027] The control device 30 applies a load F (see Figure 1) to the first workpiece W10 and the second workpiece W20 from a pair of pressurizing shafts 11 and 12 such 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 also performs the operation of energizing the first workpiece W10 and the second workpiece W20. Specifically, the control device 30 applies a load F to the first workpiece W10 and the second workpiece W20 from a pair of pressurizing shafts 11 and 12, and while the contact surface 21a of the first electrode 21 is in contact with the area of ​​the first workpiece W10 that is pressurized by the first pressurizing shaft 11, and the contact surface 22a of the second electrode 22 is in contact with the area of ​​the second workpiece W20 that is pressurized by the second pressurizing shaft 12, the control device 30 energizes the first workpiece W10 and the second workpiece W20. The control device 30 controls the flow of current X, shown by the dashed line, between the pair of electrodes 21 and 22 via the respective protrusions W11 and W21.

[0028] Each protrusion W11 and W21 is softened by the flow of current X. In this embodiment, the control device 30 applies current X to soften each protrusion W11 and W21 and applies a load F 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 each protrusion W11 and W21.

[0029] Next, we will explain how the joining process is performed at each projection W11, W21 where the first workpiece W10 and the second workpiece W20 come into contact. Figure 2 is a diagram illustrating the joining process.

[0030] The control device 30 executes the bonding process in the order shown in Figures 2(A) to (D). As shown in Figure 2(A), the pair of electrodes 21 and 22 are fixed to the pair of pressure shafts 11 and 12 by a spring 50. The biasing force of the spring 50 acts on each workpiece W10 and W20 via the pair of electrodes 21 and 22. The spring 50 is not shown in Figures 2(B) and later.

[0031] As shown in Figure 2(A), the control device 30 moves a pair of pressurizing shafts 11 and 12 toward each workpiece W10 and W20. At this time, each workpiece W10 and W20 is held between a pair of electrodes 21 and 22. A contact load of, for example, 1 kN acts on each workpiece W10 and W20 as a biasing force from a spring 50. The pair of electrodes 21 and 22 are biased to a position that protrudes approximately 1 mm toward each workpiece W10 and W20 from the pair of pressurizing shafts 11 and 12. The pair of pressurizing shafts 11 and 12 and the pair of electrodes 21 and 22 are a mechanism that is driven as a whole by a drive source (actuator 15 and 25).

[0032] Next, as shown in Figure 2(B), the control device 30 moves the pair of pressurizing shafts 11 and 12 toward each workpiece W10 and W20, and applies a load to each workpiece W10 and W20 to form protrusions. Each workpiece W10 and W20 forms protrusions W11 and W21 as a result of the load applied to form the protrusions.

[0033] Next, as shown in Figure 2(C), the control device 30 applies current to each of the protrusions W11 and W21. The control device 30 applies current to each of the protrusions W11 and W21 formed on the contact portion of each workpiece W10 and W20 to soften the contact portion of each protrusion W11 and W21. Next, as shown in Figure 2(D), the control device 30 applies current to each of the protrusions W11 and W21 while pushing the pair of pressure shafts 11 and 12 to the joining position, thereby joining the workpieces W10 and W20 at the contact portion.

[0034] Next, we will explain the changes in various parameters over time. Figure 3 is a diagram showing the changes in various parameters over time. In Figure 3, the changes in stroke, load, and current over time are shown. Note that the stroke in Figure 3 indicates that the pressurizing shafts 11 and 12 are operating with the same stroke amount, and the load in Figure 3 indicates that the pressurizing shafts 11 and 12 are acting with the same load. The values ​​shown in Figure 3 are examples and should be changed as appropriate depending on the plate thickness, material, etc. of each workpiece W10, W20.

[0035] As shown in Figure 3, the control device 30 brings the tip of the solid-state bonding device 1 closer to each workpiece W10, W20 from time T0 to time T1, and sets the stroke, which is the distance between the tip of the solid-state bonding device 1 and each workpiece W10, W20, to 0 mm at time T1. At time T1, the pair of electrodes 21, 22 are in contact with each workpiece W10, W20. From time T1 to time T2, the control device 30 applies a contact load from the pair of electrodes 21, 22 to each workpiece W10, W20. At this time, the current does not change, but the load increases by 1 kN, which is the contact load when the pair of electrodes 21, 22 are in contact with each workpiece W10, W20.

[0036] Next, the control device 30 pushes a pair of pressure shafts 11 and 12 into each workpiece W10 and W20 by 1.2 mm between time T2 and time T3, thereby forming protrusions W11 and W21. At this time, the stroke changes, and the load used to form the protrusions when pushing the pair of pressure shafts 11 and 12 into each workpiece W10 and W20 becomes 35 kN. The control device maintains the pressure due to the protrusion-forming load from time T3 to time T4. Note that the pressure due to the protrusion-forming load may change over time rather than being maintained. In this embodiment, the hardness of each workpiece W10 and W20 can be estimated using data described later, based on the reaction force detected by the detection device 40 when the amount of protrusion formation is 1.0 mm, thus enabling hardness estimation while utilizing the joining process.

[0037] Next, the control device 30 pushes the pair of pressurizing shafts 11 and 12 into the workpieces W10 and W20 by 2.4 mm between time T4 and time T5, thereby joining the protrusions W11 and W21 together. At this time, the stroke changes, and the joining load when pushing the pair of pressurizing shafts 11 and 12 into the workpieces W10 and W20 becomes 40 kN.

[0038] The control device 30 continuously supplies a current of 8kA to each protrusion W11 and W21 from time T4 to time T5. The temperature of the contact area where each protrusion W11 and W21 makes contact rises rapidly from time T4 to time T5. As a result, the softened regions of each protrusion W11 and W21 undergo plastic deformation, allowing them to be joined while remaining in a solid state. Once joining is complete, the control device 30 returns the pair of pressurizing shafts 11 and 12 to their origin position or a restartable position from time T5 to time T6. As a result, the load becomes 0. The current is also turned OFF when joining is complete.

[0039] Next, the relationship between the material used, the pressing speed, and the reaction force when pressing multiple workpieces W10 and W20 of the same thickness will be explained. Here, the load applied by the pair of pressing shafts 11 and 12 to the multiple workpieces W10 and W20 is equal to the reaction force that the pair of pressing shafts 11 and 12 receive from the multiple workpieces W10 and W20. Figure 4 is a diagram showing the relationship between the material used, the pressing speed, and the reaction force when pressing the pair of pressing shafts 11 and 12 into each workpiece W10 and W20 by 1.0 mm during the projection formation process.

[0040] The multiple circles in Figure 4 indicate the reaction force when a 780 MPa class unplated steel sheet is pressed 1.0 mm into each workpiece W10 and W20 at a speed of 5 mm / sec. The multiple triangles in Figure 4 indicate the reaction force when a 980 MPa class unplated steel sheet is pressed 1.0 mm into each workpiece W10 and W20 at a speed of 5 mm / sec. The multiple crosses in Figure 4 indicate the reaction force when a 980 MPa class unplated steel sheet is pressed 1.0 mm into each workpiece W10 and W20 at a speed of 30 mm / sec. The multiple diamonds in Figure 4 indicate the reaction force when an 1180 MPa class unplated steel sheet is pressed 1.0 mm into each workpiece W10 and W20 at a speed of 5 mm / sec. The multiple squares in Figure 4 indicate the reaction force when an 1180 MPa class GA steel sheet is pressed 1.0 mm into each workpiece W10 and W20 at a speed of 5 mm / sec. Note that the MPa class indicates the tensile strength of the material. Furthermore, GA steel sheets are steel sheets that have been hot-dip galvanized and then reheated to alloy the galvanizing with the metal.

[0041] As shown in Figure 4, the multiple circular marks in the 780 MPa class, which have a lower tensile strength, exhibit the smallest reaction force. The multiple triangular marks and multiple cross marks in the 980 MPa class, which have a higher tensile strength than the 780 MPa class, exhibit a larger reaction force than the multiple circular marks. Furthermore, the multiple diamond-shaped marks and multiple square marks in the 1180 MPa class, which have a higher tensile strength than the 980 MPa class, exhibit a larger reaction force than the multiple triangular marks and multiple cross marks.

[0042] On the other hand, multiple triangular marks and multiple cross marks of the same 980 MPa class produce almost the same reaction force regardless of the pressing speed. Similarly, multiple diamond marks and multiple square marks of the same 1180 MPa class produce almost the same reaction force regardless of whether or not plating is present. Thus, it can be seen that the magnitude of the reaction force depends on the tensile strength of the multiple workpieces W10 and W20, and is hardly affected by the pressing speed or the presence or absence of plating. Therefore, if the reaction force (load) when a pair of pressurizing shafts 11 and 12 are pressed into multiple workpieces W10 and W20 is known, the tensile strength of the material can be estimated. The tensile strength of the material (e.g., MPa) and the hardness of the material (e.g., HV) can be converted from each other using a conversion table pre-stored in the memory device 33. For this reason, the hardness of the material can be estimated from the reaction force when a pair of pressurizing shafts 11 and 12 are pressed into multiple workpieces W10 and W20.

[0043] In the solid-state bonding apparatus 1, durability evaluation data showing the relationship between the reaction force when a pair of pressure shafts 11 and 12 are pressed into multiple workpieces W10 and W20, and the estimated hardness of the workpieces W10 and W20 corresponding to that reaction force, is stored in the memory device 33 based on prior experiments. For example, the data shown in Figure 5 is stored in the memory device 33. Figure 5 is a diagram illustrating the data used to control the control device 30.

[0044] As shown in Figure 5, estimated hardness is set for each of the reaction force range names (R1 to R5) corresponding to multiple reaction force ranges. Reaction force range name R1 covers the range of reaction force less than 19.3kN when a pair of pressurizing shafts 11 and 12 are pressed into multiple workpieces W10 and W20. The estimated hardness of reaction force range name R1 is 183HV or less, and the estimated strength is 590MPa or less. The upper limit of the number of joints in reaction force range name R1 is set to L1 from prior experiments, and the current number of joints corresponds to C1. Reaction force range name R2 covers the range of reaction force between 19.3kN and 23.9kN when a pair of pressurizing shafts 11 and 12 are pressed into multiple workpieces W10 and W20. The estimated hardness of reaction force range name R2 is 245HV class, and the estimated strength is 780MPa class. The upper limit of the number of joints in reaction force range name R2 is set to L2 from prior experiments, and the current number of joints corresponds to C2.

[0045] Reaction force range R3 covers the range of reaction force between 23.9kN and less than 27.8kN when a pair of pressurizing shafts 11 and 12 are pressed into multiple workpieces W10 and W20. The estimated hardness for reaction force range R3 is 310HV class, and the estimated strength is 980MPa class. The upper limit of the number of joints in reaction force range R3 is set to L3 based on prior experiments, and the current number of joints corresponds to C3. Reaction force range R4 covers the range of reaction force between 27.8kN and less than 32.5kN when a pair of pressurizing shafts 11 and 12 are pressed into multiple workpieces W10 and W20. The estimated hardness for reaction force range R4 is 372HV class, and the estimated strength is 1180MPa class. The upper limit of the number of joints in reaction force range R4 is set to L4 based on prior experiments, and the current number of joints corresponds to C4.

[0046] The reaction force range R5 targets a reaction force of 32.5 kN or more when a pair of pressurizing shafts 11 and 12 are pressed into multiple workpieces W10 and W20. The estimated hardness for reaction force range R5 is 471 HV or higher, and the estimated strength is 1470 MPa or higher. The upper limit of the number of joining operations in reaction force range R5 is set to L5 based on prior experiments, and the current number of joining operations corresponds to C5. Thus, the data shown in Figure 5 accurately indicates the upper limit of the number of joining operations from the reaction force range. The current number of joining operations increases each time the joining process is executed and is stored in memory 32. Note that although the reaction force range is divided into 5 stages in Figure 5, the number of stages can be any number as long as multiple stages are available for the reaction force range.

[0047] Next, a simplified example of the calculations performed by the control device 30 will be explained. Figure 6 is a diagram for a simplified explanation of the calculations performed by the control device 30. From Figure 6(a) to Figure 6(b), the current number of connections in the corresponding reaction force range R4 changes when a reaction force of 30kN is detected. In the data shown in Figure 6(a), the upper limit number of connections in reaction force range R1 is set to 5, the upper limit number of connections in reaction force range R2 is set to 4, the upper limit number of connections in reaction force range R3 is set to 3, the upper limit number of connections in reaction force range R4 is set to 2, and the upper limit number of connections in reaction force range R5 is set to 1. Also, the current number of connections is 2 for reaction force range R2 and 1 for reaction force range R4.

[0048] Assume that the reaction force P1 = 30kN is detected by the detection device 40 from the state shown in Figure 6(a). In this case, as shown in Figure 6(b), the current number of joints in the reaction force range R4 changes from 1 to 2. The control device 30 uses the calculation device 31 to calculate which of the following inequalities holds true: L1 ≤ C1 + C2 + C3 + C4 + C5, L2 ≤ C2 + C3 + C4 + C5, L3 ≤ C3 + C4 + C5, L4 ≤ C4 + C5, or L5 ≤ C5.

[0049] For example, in Figure 6(b), the inequality holds in the reaction force ranges R2 and R4 circled in Figure 6(b), where L1=5≦0+2+0+2+0, L2=4≦2+0+2+0, L3=3≦0+2+0, L4=2≦2+0, or L5=1≦0. When the inequality holds, the control device 30 determines that there is a possibility of damage to the pair of pressurizing shafts 11 and 12 and notifies that damage is predicted. The specific control details will be explained using the flowchart in Figure 7.

[0050] Figure 7 is a flowchart showing the control actions performed by the control device 30 (arithmetic unit 31). The processes in the flowchart of Figure 7 are repeatedly called and executed as subroutines from the main routine in the control of the control device 30. First, in step S (hereinafter simply referred to as "S") 1, the control device 30 starts a joining operation that moves a pair of pressurizing shafts 11 and 12 toward the first workpiece W10 and the second workpiece W20.

[0051] Next, the control device 30 assigns 0 to the variable Pi (i=1~3) (S2). Here, the variables are set as follows: P1 is the reaction force (first reaction force) when the indentation amount of the pair of pressurizing shafts 11, 12 reaches 1.0 mm; P2 is the reaction force (second reaction force) when the indentation amount of the pair of pressurizing shafts 11, 12 reaches 1.2 mm; and P3 is the reaction force (third reaction force) when the indentation amount of the pair of pressurizing shafts 11, 12 reaches 2.4 mm. The state of indentation amount of 1.0 mm corresponds to the intermediate state of projection formation. The state of indentation amount of 1.2 mm corresponds to the completed state (end position) of projection formation. The state of indentation amount of 2.4 mm corresponds to the completed state (end position) of joining indentation.

[0052] Next, the control device 30 determines whether the indentation amount of the pair of pressure shafts 11 and 12 has reached 1.0 mm (S3). If the control device 30 determines that the indentation amount of the pair of pressure shafts 11 and 12 has not reached 1.0 mm (NO in S3), it repeats the process in S3. If the control device 30 determines that the indentation amount of the pair of pressure shafts 11 and 12 has reached 1.0 mm (YES in S3), it stores the reaction force detected by the detection device 40 as P1 (S4).

[0053] Next, the control device 30 determines whether the amount of indentation of the pair of pressure shafts 11 and 12 has reached 1.2 mm, which is the end position for projection formation (S5). If the control device 30 determines that the amount of indentation of the pair of pressure shafts 11 and 12 has not reached 1.2 mm (NO in S5), it repeats the process in S5. If the control device 30 determines that the amount of indentation of the pair of pressure shafts 11 and 12 has reached 1.2 mm (YES in S5), it stores the reaction force detected by the detection device 40 as P2 (S6).

[0054] Next, the control device 30 determines whether the amount of indentation of the pair of pressure shafts 11 and 12 has reached 2.4 mm, which is the end position of the joining indentation (S7). If the control device 30 determines that the amount of indentation of the pair of pressure shafts 11 and 12 has not reached 2.4 mm (NO in S7), it repeats the process in S7. If the control device 30 determines that the amount of indentation of the pair of pressure shafts 11 and 12 has reached 2.4 mm (YES in S7), it stores the reaction force detected by the detection device 40 as P3 (S8).

[0055] Next, the control device 30 terminates the bonding operation (S9). In the process of S9, the control device 30 separates the pair of pressurizing shafts 11 and 12 from the respective workpieces W10 and W20 and stops supplying current to the pair of electrodes 21 and 22. Next, the control device 30 determines, using data as shown in Figure 6, whether or not the reaction force P1 stored in S4 belongs to which reaction force range Ra (1 ≤ a ≤ n) (S10).

[0056] Next, the control device 30 uses the data shown in Figure 6 to determine the estimated hardness (estimated strength) of each workpiece W10 and W20 from the reaction force range obtained in S10 (S11). In this way, the solid-state bonding apparatus 1 can determine the estimated hardness (estimated strength) of each workpiece W10 and W20 using the first reaction force in the projection formation step of the bonding process. Next, the control device 30 increases the current number of bonding cycles by 1 by substituting Ca+1 for Ca, which indicates the current number of bonding cycles (S12).

[0057] Next, the control device 30 calculates whether any of the following inequalities hold true: L1≦C1+C2+C3…Cn, L2≦C2+C3…Cn, ..., or Ln≦Cn (S13). The process in S13 determines whether the judgment condition is met based on data showing the upper limit of the number of joints corresponding to the hardness estimated from the reaction force as shown in Figure 6, and the number of joints up to the present. If the control device 30 determines in S13 that any of the inequalities holds true (YES in S13), it displays a message indicating that failure of the pair of pressurizing shafts 11 and 12 is predicted (S16) and terminates the process. The process in S16 is the process by which the control device 30 displays information regarding the predicted failure to the display device 70.

[0058] If the control device 30 determines in S13 that neither inequality holds true (NO in S13), it determines whether the reaction force P2 stored in S6 is 55kn or more, or whether the reaction force P3 stored in S8 is 55kn or more (S14). If the control device 30 determines that the reaction force P2 or reaction force P3 is 55kn or more (YES in S14), it displays a message indicating that damage to the pair of pressurizing shafts 11 and 12 is predicted (S16) and terminates the process. A reaction force P2 or reaction force P3 of 55kn or more indicates that the pair of pressurizing shafts 11 and 12 are under excessive load. Therefore, if such a high reaction force is detected, regardless of the process in S13, it displays a message indicating that damage to the pair of pressurizing shafts 11 and 12 is predicted to prevent damage to the pair of pressurizing shafts 11 and 12. Note that the determination values ​​for the second reaction force P2 and the third reaction force P3 may be different.

[0059] In S13, if the control device 30 determines that the reaction force P2 or reaction force P3 is less than 55kN (NO in S14), it displays how many more times joining is possible with the same material (S15) and terminates the process. In S15, the control device 30 determines that La-(Ca+Ca +1The calculation of ...+Cn) is performed. The calculation performed in S15 subtracts the total number of joints in the reaction force range below the reaction force range Ra from the upper limit number of joints in the reaction force range Ra. The user can determine the remaining number of joints that can be performed using the pair of pressurizing shafts 11 and 12 by the calculation performed in S15.

[0060] According to the solid-phase bonding apparatus 1 of Embodiment 1, based on the reaction force P1 when a pair of pressurizing shafts 11, 12 are pressed in so that protrusions W11, W21 are formed on each workpiece W10, W20, it is possible to display a message indicating that the pair of pressurizing shafts 11, 12 are predicted to break based on the hardness of each workpiece W10, W20 estimated using data stored in the storage device 33. This makes it possible to predict the breakage of the pair of pressurizing shafts 11, 12 by utilizing the bonding process during the formation of protrusions on each workpiece W10, W20 and estimating the hardness of the first workpiece W10 and the second workpiece W20.

[0061] <Summary> (1) This disclosure relates to a solid-state bonding apparatus 1 for bonding a first workpiece W10 and a second workpiece W20, which are conductive and overlap in the thickness direction, in a solid state. The solid-state bonding apparatus 1 comprises 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 arranged around the pair of pressure shafts 11, 12, a detection device 40 that detects the reaction force when the first workpiece W10 and the second workpiece W20 are pressed, a storage device 33 that stores data showing the relationship between the reaction force and the hardness of the first workpiece W10 and the second workpiece W20, and a control device 30. The control device 30 presses the first workpiece W10 and the second workpiece W20 with a pair of pressurizing shafts 11 and 12 to form protrusions, and then further presses the pair of pressurizing shafts 11 and 12 while supplying power to a pair of electrodes 21 and 22 to join the first workpiece W10 and the second workpiece W20 in a solid state. Based on the first reaction force detected by the detection device 40 during the formation of the protrusions, the control device 30 estimates the hardness using the data.

[0062] According to the solid-phase bonding apparatus 1 of this disclosure, the hardness of the first workpiece W10 and the second workpiece W20 can be estimated by utilizing the bonding process during which protrusions are formed on the first workpiece W10 and the second workpiece W20.

[0063] (2) In the solid-state bonding apparatus 1 of (1), the data further includes the relationship between hardness and the upper limit of the number of bonding cycles until the pair of pressurizing shafts 11 and 12 break. The control device 30 predicts the breakage of the pair of pressurizing shafts 11 and 12 using the upper limit of the number of bonding cycles corresponding to the hardness estimated from the first reaction force and the number of bonding cycles up to the present.

[0064] According to the solid-state bonding apparatus 1 of this disclosure, the control device 30 can predict the failure of a pair of pressurizing shafts 11 and 12 using the upper limit of the number of bonding cycles corresponding to the hardness estimated from the first reaction force and the number of bonding cycles to date.

[0065] (3) The solid-phase bonding apparatus 1 of (2) is further equipped with a display device 70. The control device 30 displays on the display device 70 that damage to the pair of pressurizing shafts 11 and 12 is predicted when a determination condition using the upper limit number of bonding times and the number of bonding times to date is met.

[0066] According to the solid-phase bonding apparatus 1 of this disclosure, data can be used to display on the display device 70 that damage to a pair of pressurizing shafts 11 and 12 is predicted.

[0067] (4) In the solid-phase bonding apparatus 1 of (3), if the determination condition is not met, the control device 30 displays on the display device 70 the remaining number of bonding operations that can be performed using the pair of pressurizing shafts 11 and 12.

[0068] According to the solid-phase bonding apparatus 1 of this disclosure, the remaining number of bonding operations that can be performed using a pair of pressurizing shafts 11 and 12 can be displayed on the display device 70 using the data.

[0069] (5) In the solid-state bonding apparatus 1 of (3), the control device 30 displays on the display device 70 that damage to the pair of pressurizing shafts 11 and 12 is expected if the second reaction force at the position where the formation of the protrusion is completed is greater than or equal to a predetermined value.

[0070] According to the solid-state bonding apparatus 1 of this disclosure, based on the second reaction force at the position where the formation of the protrusion is completed, the display device 70 can display a message indicating that damage to the pair of pressurizing shafts 11 and 12 is predicted.

[0071] (6) In the solid-state bonding apparatus 1 of (3), the control device 30 displays on the display device 70 that damage to the pair of pressurizing shafts 11 and 12 is expected if the third reaction force at the position where the bonding of the first workpiece W10 and the second workpiece W20 is completed is greater than or equal to a predetermined value.

[0072] According to the solid-phase bonding apparatus 1 of this disclosure, based on the third reaction force at the position where the bonding of the first workpiece W10 and the second workpiece W20 is completed, the display device 70 can display a message indicating that damage to the pair of pressurizing shafts 11 and 12 is predicted.

[0073] (7) This disclosure relates to a method for estimating the hardness of a first workpiece W10 and a second workpiece W20 by computer, used in a solid-state bonding apparatus 1 for bonding conductive, overlapping workpieces W10 and W20 in a solid state. The solid-state bonding apparatus 1 includes a pair of pressurizing shafts 11 and 12 that press the first workpiece W10 and the second workpiece W20 from both sides in the thickness direction, a pair of electrodes 21 and 22 arranged around the pair of pressurizing shafts 11 and 12, respectively, a detection device 40 that detects the reaction force when the first workpiece W10 and the second workpiece W20 are pressed, and a storage device that stores data showing the relationship between the reaction force and the hardness of the first and second workpieces. The process performed by the computer includes the steps of forming protrusions by pressing the first workpiece W10 and the second workpiece W20 with a pair of pressurizing shafts 11 and 12, and then further pressing the pair of pressurizing shafts 11 and 12 while supplying power to a pair of electrodes 21 and 22 to join the first workpiece W10 and the second workpiece W20 in a solid state, and estimating the hardness using data based on the first reaction force detected by the detection device 40 during the formation of the protrusions.

[0074] According to the estimation method of this disclosure, the hardness of the first workpiece W10 and the second workpiece W20 can be estimated by utilizing the processing of the joining process during the formation of protrusions on the first workpiece W10 and the second workpiece W20.

[0075] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0076] 1 Solid-phase bonding apparatus, 10 Solid-phase bonding equipment, 11,12 Pressing shaft, 11a,12a Pressing surface, 15,25 Actuator, 21,22 Electrode, 21a,22a Contact surface, 30 Control device, 31 Calculation unit, 32 Memory, 33 Storage device, 34 Input / Output interface, 40 Detection device, 50 Spring, 60 Power supply unit, 70 Display device, 330 Control program, F Load, W10,W20 Workpiece, W11,W21 Protrusion, X Current.

Claims

1. A solid-phase bonding apparatus for joining a first workpiece and a second workpiece that are conductive and overlap in the thickness direction in a solid-phase state, A pair of pressure shafts that press the first workpiece and the second workpiece from both sides in the thickness direction, A pair of electrodes are arranged around the pair of pressure shafts, A detection device for detecting the reaction force when the first workpiece and the second workpiece are pressed, A storage device that stores data showing the relationship between the reaction force and the hardness of the first and second workpieces, Equipped with a control device, The control device is After pressing the first and second workpieces with the pair of pressure shafts to form protrusions, the pair of pressure shafts are further pressed while supplying power to the pair of electrodes, thereby joining the first and second workpieces in a solid state. A solid-phase bonding apparatus that estimates the hardness using the data based on a first reaction force detected by the detection device during the formation of the aforementioned protrusion.

2. The data further includes the relationship between the hardness and the maximum number of joining cycles until the pair of pressurizing shafts break, The solid-phase bonding apparatus according to claim 1, wherein the control device predicts the failure of the pair of pressurizing shafts using the upper limit number of bonding cycles corresponding to the hardness estimated from the first reaction force and the number of bonding cycles to date.

3. Further equipped with a display device, The solid-phase bonding apparatus according to claim 2, wherein the control device displays on the display device that damage to the pair of pressurizing shafts is predicted when a determination condition using the upper limit number of bonding times and the number of bonding times up to the present is met.

4. The solid-phase bonding apparatus according to claim 3, wherein the control device displays the remaining number of bonding operations that can be performed using the pair of pressure shafts on the display device when the determination condition is not met.

5. The solid-phase bonding apparatus according to claim 3, wherein the control device displays on the display device that damage to the pair of pressurizing shafts is predicted when the second reaction force at the position where the formation of the protrusion is completed exceeds a predetermined value.

6. The solid-phase bonding apparatus according to claim 3, wherein the control device displays on the display device that damage to the pair of pressurizing shafts is predicted when the third reaction force at the position where the joining of the first workpiece and the second workpiece is completed exceeds a predetermined value.

7. A method for estimating the hardness of a first workpiece and a second workpiece, which are conductive and overlap in the thickness direction, using a computer, in a solid-state bonding apparatus used for bonding these workpieces in a solid state, The solid-phase bonding apparatus is A pair of pressure shafts that press the first workpiece and the second workpiece from both sides in the thickness direction, A pair of electrodes are arranged around the pair of pressure shafts, A detection device for detecting the reaction force when the first workpiece and the second workpiece are pressed, The system includes a storage device that stores data showing the relationship between the reaction force and the hardness of the first and second workpieces. The process to be performed by the aforementioned computer is: The steps include: pressing the first workpiece and the second workpiece with the pair of pressure shafts to form protrusions, and then further pressing the pair of pressure shafts while supplying power to the pair of electrodes to join the first workpiece and the second workpiece in a solid state; An estimation method comprising the step of estimating the hardness using the data based on a first reaction force detected by the detection device during the formation of the protrusion.

Images