Welding device

Abstract

A welding device 1 comprises: a heating body 14 that is composed of a fiber-reinforced resin in which fibers are arranged in one direction and is disposed between a first adherend 10 and a second adherend 12; a plurality of systems of electrodes 20 that are attached to the heating body 14 and divide an energization region in the heating body 14 in a direction intersecting an extension direction of the fibers; a power supply device 22 that applies a voltage to the electrodes 20 to cause a current to flow in the extension direction in the heating body 14; and a pressurizing device 24 for welding the first adherend 10 and the second adherend 12 via the heating body 14 by applying pressure to at least one of the first adherend 10 and the second adherend 12 in a direction in which the first adherend 10 and the second adherend 12 approach each other in a state in which the heating body 14 is heated by the current flowing through the heating body 14.

Description

Welding Equipment

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2023-188609, filed November 2, 2023, the contents of which are incorporated herein by reference.

[0002] For example, Patent Document 1 discloses a technique for welding a first composite material and a second composite material. In Patent Document 1, a first protective sheet is arranged so as to contact the first composite material, a second protective sheet is arranged so as to contact the second composite material, and an electrically conductive sheet is arranged between the first protective sheet and the second protective sheet. In Patent Document 1, a voltage is applied to the electrodes of the electrically conductive sheet, and the first composite material and the second composite material are welded together via the first protective sheet, the second protective sheet, and the electrically conductive sheet.

[0003] International Publication No. 2022 / 044254

[0004] For example, the resistance distribution may be uneven in some areas of the conductive sheet to which voltage is applied, which can result in uneven temperature distribution in the conductive sheet when voltage is applied to the conductive sheet, which can result in reduced welding quality.

[0005] An object of the present disclosure is to provide a welding device that can suppress deterioration in welding quality.

[0006] In order to solve the above problem, a welding device according to one embodiment of the present disclosure comprises a heating element made of fiber-reinforced resin with fibers arranged in one direction and arranged between a first adherend and a second adherend; multiple systems of electrodes attached to the heating element and dividing the current-carrying area in the heating element in a direction intersecting the extension direction of the fibers; a power supply unit that applies a voltage to the electrodes to cause current to flow in the heating element in the extension direction; and a pressure device that, when the heating element is heated by the current flowing through it, applies pressure to at least one of the first adherend and the second adherend in a direction that moves the first adherend and the second adherend closer to each other, thereby welding the first adherend and the second adherend via the heating element.

[0007] Furthermore, the electrodes of adjacent systems among the electrodes of the plurality of systems may be insulated from each other by an insulator.

[0008] Furthermore, a conduction assisting material that assists electrical conduction between the electrodes and the heating element may be applied to the heating element at the positions where the electrodes are attached.

[0009] Furthermore, the electrodes may be attached to the heating element in a state where at least a portion of the resin constituting the fiber reinforced resin is removed from the position on the heating element where the electrodes are to be attached.

[0010] The device may further include a control device that controls the power supply device and the pressure device, and the control device may be configured to cause the power supply device to apply voltage individually to the electrodes of each system so that the temperature of the current-carrying areas in the heating element is substantially uniform in the multiple current-carrying areas.

[0011] In order to solve the above problem, a welding apparatus according to one embodiment of the present disclosure comprises a plurality of heating elements arranged at a distance from each other and positioned between a first adherend and a second adherend, electrodes individually attached to the plurality of heating elements, a power supply unit that applies a voltage to the electrodes to pass an electric current through the heating elements, and a pressure device that, when the heating elements are heated by the electric current flowing through them, applies pressure to at least one of the first adherend and the second adherend in a direction that moves the first adherend and the second adherend closer to each other, thereby welding the first adherend and the second adherend via the heating elements.

[0012] Further, adjacent heating elements among the plurality of heating elements may be insulated from each other by an insulator.

[0013] The apparatus may further include a control device for controlling the power supply device and the pressure device, and the control device may be configured to cause the power supply device to apply voltage individually to the electrodes of each heating element so that the temperatures of the heating elements are substantially uniform across the multiple heating elements.

[0014] According to the present disclosure, it is possible to suppress deterioration in welding quality.

[0015] FIG. 1 is a schematic diagram showing an example of the configuration of a welding device according to a first embodiment. FIG. 2 is a plan view illustrating the current flowing through a heating element in the first embodiment. FIG. 3 is a flowchart illustrating the flow of welding using the welding device according to the first embodiment. FIG. 4 is a diagram illustrating an example of the transition of the temperature of the heating element when welding is performed by the welding device according to the first embodiment. FIG. 5 is a diagram illustrating an example of the transition of the voltage applied to the electrodes in the welding device according to the first embodiment. FIG. 6 is a schematic diagram showing an example of the configuration of a welding device according to a second embodiment. FIG. 7 is a plan view illustrating the current flowing through a heating element in the second embodiment.

[0016] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0017] 1 is a schematic diagram showing an example of the configuration of a welding apparatus 1 according to a first embodiment. The welding apparatus 1 of the first embodiment includes a first adherend 10, a second adherend 12, a heating element 14, a first positive electrode 20a1, a first negative electrode 20b1, a second positive electrode 20a2, a second negative electrode 20b2, a power supply device 22, a pressure device 24, and a control device 30.

[0018] The first adherend 10 and the second adherend 12 are members to be welded together by the welding device 1. The first adherend 10 and the second adherend 12 are made of, for example, a fiber-reinforced resin such as carbon fiber reinforced plastic (CFRP). Note that the first adherend 10 and the second adherend 12 are not limited to fiber-reinforced resin, and may be made of any material such as a thermoplastic resin. Furthermore, the material of the first adherend 10 and the material of the second adherend 12 may be the same or different.

[0019] The first adherend 10 and the second adherend 12 may be, for example, flat plates or angle plates whose surfaces to be welded are flat. The first adherend 10 and the second adherend 12 may also be curved plates whose surfaces to be welded are curved. The first adherend 10 and the second adherend 12 are not limited to the shapes shown as examples, and may be any shape that has at least a surface to be welded.

[0020] The heating element 14 is made of, for example, a fiber-reinforced resin such as carbon fiber reinforced plastic (CFRP). More specifically, the heating element 14 is made of a fiber-reinforced resin in which the fibers are oriented in one direction. For example, the heating element 14 may be made of a carbon fiber reinforced resin prepreg in which the carbon fibers are oriented in one direction. Hereinafter, the direction in which the fibers composing the heating element 14 extend may be referred to as the fiber extension direction or the extension direction of the heating element 14.

[0021] In the heating element 14, the electrical resistance in the direction in which the fibers extend is lower than the electrical resistance in the direction intersecting the direction in which the fibers extend. Therefore, when a voltage is applied to the heating element 14, current flows easily along the direction in which the fibers extend. On the other hand, in the heating element 14, current does not flow easily in the direction intersecting the direction in which the fibers extend. In other words, in the heating element 14 made of a fiber-reinforced resin in which the fibers are arranged in one direction, there is anisotropy in the direction in which the current flows.

[0022] Hereinafter, the flow of electric current may be referred to as "energization." Furthermore, the direction in which electric current flows in the heating element 14 may be referred to as the "current flow direction." When the heating element 14 is made of fiber-reinforced resin in which the fibers are arranged in one direction, the current flow direction is substantially the same as the extension direction of the fibers. The heating element 14 generates heat when electric current flows through it. That is, the temperature of the heating element 14 becomes higher when it is energized compared to when it is not energized. When the temperature of the heating element 14 reaches a predetermined temperature or higher, the resin on the surface of the heating element 14 softens.

[0023] The heating element 14 is formed in a sheet shape. The length of the heating element 14 in the extending direction is longer than the areas of the first adherend 10 and the second adherend 12 to be welded.

[0024] The first adherend 10 and the second adherend 12 are disposed opposite each other. For example, the first adherend 10 is disposed on a work table 40. The second adherend 12 is disposed on the opposite side of the work table 40 from the first adherend 10.

[0025] The heating element 14 is disposed between the first adherend 10 and the second adherend 12. In this state, both ends of the heating element 14 in the extension direction of the fibers extend outward from the first adherend 10 and the second adherend 12. One of the two surfaces of the heating element 14 abuts against the surface of the first adherend 10 to be welded. The other of the two surfaces of the heating element 14 abuts against the surface of the second adherend 12 to be welded.

[0026] As described above, of the first adherend 10 and the second adherend 12, the second adherend 12 is placed on the opposite side of the heating element 14 from the work table 40. A pressure jig 42 is placed on the surface of the second adherend 12 opposite the surface that contacts the heating element 14.

[0027] The pressing jig 42 is formed, for example, in the shape of a block having a surface that comes into contact with the second adherend 12. The shape of the pressing jig 42 is not limited to the illustrated shape, and may be any shape.

[0028] The pressure device 24 is connected to the pressure jig 42. The pressure device 24 is configured to be able to move the pressure jig 42 in a direction approaching the work table 40 by using a driving source such as hydraulic pressure.

[0029] That is, the pressure device 24 is configured to be able to apply pressure to at least one of the first adherend 10 and the second adherend 12 in a direction in which the first adherend 10 and the second adherend 12 approach each other via the pressure jig 42. For example, in a mode in which the pressure jig 42 is in contact with the second adherend 12, the pressure device 24 is configured to be able to apply pressure to the second adherend 12 via the pressure jig 42.

[0030] Hereinafter, the direction in which pressure is applied, i.e., the direction in which pressure is applied, may be referred to as the pressure direction. The pressure direction roughly corresponds to the direction intersecting the surface of the heating element 14, i.e., the thickness direction of the heating element 14. Furthermore, the direction intersecting the current flow direction in the heating element 14 (in other words, the extension direction of the fibers) and the pressure direction applied by the pressure device 24 may be referred to as the width direction of the heating element 14.

[0031] Of the first adherend 10 and the second adherend 12, the first adherend 10 may be placed on the opposite side of the work table 40 from the heating element 14. In this embodiment, the pressure jig 42 is placed on the surface of the first adherend 10 opposite the surface that abuts against the heating element 14. In this embodiment, the pressure device 24 may be configured to be able to apply pressure to the first adherend 10 via the pressure jig 42.

[0032] In addition, the workbench 40 may be omitted, and a pressure jig 42 may be placed on both the first adherend 10 and the second adherend 12, with the pressure device 24 applying pressure to both the first adherend 10 and the second adherend 12.

[0033] The pressure device 24 applies pressure to the first adherend 10 and the second adherend 12 while the heating element 14 is being heated by current flowing through the heating element 14. This causes the heating element 14 to be welded to the first adherend 10 and the second adherend 12. As a result, the first adherend 10 and the second adherend 12 are welded via the heating element 14. In other words, the welding device 1 performs resistance welding.

[0034] The heating element 14 is energized by a first positive electrode 20 a 1 , a first negative electrode 20 b 1 , a second positive electrode 20 a 2 , a second negative electrode 20 b 2 and a power supply 22 .

[0035] Hereinafter, the first positive electrode 20a1, the first negative electrode 20b1, the second positive electrode 20a2, and the second negative electrode 20b2 may be collectively referred to simply as electrodes 20. The first positive electrode 20a1 and the first negative electrode 20b1 may be collectively referred to simply as first electrodes. The second positive electrode 20a2 and the second negative electrode 20b2 may be collectively referred to simply as second electrodes.

[0036] Each of the electrodes 20 is placed on, for example, a workbench 40. The electrodes 20 are made of, for example, a conductive metal material. The electrodes 20 are attached to both ends of the heating element 14 in the extension direction of the fibers. A plurality of systems of electrodes 20 are provided for each heating element 14 in the width direction of the heating element 14. Note that the system here means a group that forms a single closed circuit. Therefore, multiple systems means that the electrodes are divided into multiple groups, and that there are multiple pairs of electrodes that form a single closed circuit.

[0037] More specifically, the positive first electrode 20a1 is attached to one end of the heating element 14. The negative first electrode 20b1 is attached to the other end of the heating element 14. The positive first electrode 20a1 and the negative first electrode 20b1 are attached closer to one side in the width direction of the heating element 14. The positive first electrode 20a1 and the negative first electrode 20b1 belong to the same system.

[0038] The positive second electrode 20a2 is attached to one end of the heating element 14. The negative second electrode 20b2 is attached to the other end of the heating element 14. The positive second electrode 20a2 and the negative second electrode 20b2 are attached closer to the other widthwise side of the heating element 14. The positive second electrode 20a2 and the negative second electrode 20b2 belong to a separate system from the positive first electrode 20a1 and the negative first electrode 20b1.

[0039] Each electrode 20 includes two electrode segments 50 and an electrode fixing member 52. The two electrode segments 50 are arranged opposite each other, and, for example, their opposing surfaces are flat. The end of the heating element 14 is arranged between the two electrode segments 50. The electrode fixing member 52 fixes the two electrode segments 50 to the work table 40 with the end of the heating element 14 arranged between the two electrode segments 50. The end of the heating element 14 is sandwiched between the two electrode segments 50.

[0040] The power supply unit 22 is electrically connected to each electrode 20. The power supply unit 22 is configured to be able to apply a voltage to the electrodes 20. By applying a voltage to the electrodes 20, the power supply unit 22 is able to pass a current in the extension direction of the fibers in the heating element 14.

[0041] More specifically, the power supply device 22 applies a first voltage between the positive first electrode and the negative first electrode. Meanwhile, the power supply device 22 applies a second voltage, independent of the first voltage, between the positive second electrode and the negative second electrode. That is, the power supply device 22 is capable of applying independent voltages to multiple independent systems. Note that the power supply device 22 applies, for example, a DC voltage to the electrodes 20, but is not limited to a DC voltage. The power supply device 22 may also apply an AC voltage or a pulsed voltage to the electrodes 20.

[0042] The control device 30 includes one or more processors and one or more memories connected to the processors. The memories include a ROM in which programs and the like are stored and a RAM as a work area. The processor controls the entire welding device 1 in cooperation with the programs stored in the memory. For example, the control device 30 controls the power supply device 22 and the pressure device 24. The control device 30 will be described in detail later.

[0043] 2 is a plan view illustrating the current flowing through the heating element 14 in the first embodiment. The white arrows A1 and A2 in FIG. 2 indicate the direction in which the current flows.

[0044] As shown in FIG. 2, the first positive electrode 20a1 and the first negative electrode 20b1 are located above the center of the heating element 14 in the width direction in FIG.

[0045] When a first voltage is applied between the positive first electrode 20a1 and the negative first electrode 20b1, current flows in a region in FIG. 2 that is above the center of the width of the heating element 14, as indicated by the outline arrow A1, depending on the positions of the positive first electrode 20a1 and the negative first electrode 20b1. Hereinafter, the region in the heating element 14 through which current flows in response to the first voltage of the first electrode may be referred to as the first current-carrying region. In FIG. 2, the first current-carrying region is illustrated by region B1 surrounded by a dashed line. The current value of the current flowing in the first current-carrying region can be set to a value corresponding to the first voltage.

[0046] As shown in FIG. 2, the positive second electrode 20a2 and the negative second electrode 20b2 are located below the center of the heating element 14 in the width direction in FIG.

[0047] When a second voltage is applied between the positive second electrode 20a2 and the negative second electrode 20b2, current flows in a region in FIG. 2 that is lower than the center in the width direction of the heating element 14, as indicated by the outline arrow A2, depending on the positions of the positive second electrode 20a2 and the negative second electrode 20b2. Hereinafter, the region in the heating element 14 through which current flows in response to the second voltage of the second electrode may be referred to as the second current-carrying region. In FIG. 2, the second current-carrying region is illustrated by region B2 surrounded by a dashed line. The current value of the current flowing in the second current-carrying region can be set to a value corresponding to the second voltage.

[0048] In this way, in the welding device 1, the current-carrying region in the heating element 14, through which current flows, is divided in the width direction of the heating element 14. In the example of Fig. 2, the current-carrying region is divided into two regions, a first current-carrying region and a second current-carrying region, in the width direction of the heating element 14.

[0049] This allows the welding device 1 to control the temperature distribution of the heating element 14 in accordance with the first voltage and the second voltage, and to control the amount of heat generated for each current-carrying region, thereby enabling the welding device 1 to precisely control the temperature distribution of the heating element 14, and to make the temperature distribution of the heating element 14 substantially uniform, for example.

[0050] Here, an example has been described in which two systems of electrodes 20 are provided and the current-carrying region is divided into two. However, the electrodes 20 are not limited to being provided in two systems, and any number of systems, such as three or more systems, may be provided. In this case, the current-carrying region is divided into the same number of systems as the electrodes 20. In this embodiment, the greater the number of divided current-carrying regions, the more precisely the temperature distribution of the heating element 14 can be controlled.

[0051] 2, the first and second electrodes are attached to the heating element 14 at approximately equal intervals in the width direction of the heating element 14 so that the current-carrying region is approximately uniform in the width direction of the heating element 14. However, the first and second electrodes may be attached to the heating element 14 at any ratio in the width direction of the heating element 14. In this case, the current-carrying region is divided so that the area ratio corresponds to the ratio of the attachment positions of the first and second electrodes. In this embodiment, it is possible to control the temperature distribution of the heating element 14 in more detail.

[0052] 2, insulating members 60, which are sheet-like insulators having insulating properties, are disposed between the first positive electrode 20a1 and the second positive electrode 20a2, and between the first negative electrode 20b1 and the second negative electrode 20b2. That is, the insulators insulate electrical continuity between the electrodes 20 of adjacent systems among the electrodes 20 of the multiple systems.

[0053] This makes it possible to prevent electrical short circuits between the first electrode and the second electrode, i.e., between the electrodes 20 of adjacent systems, in the welding device 1. As a result, the welding device 1 can more appropriately divide the current-carrying area.

[0054] Furthermore, a conduction assisting material 62 that assists electrical conduction between the electrode 20 and the heating element 14 is applied to the position of the heating element 14 where the electrode 20 is attached. The conduction assisting material 62 is, for example, silver paste or plating. After the conduction assisting material 62 has been applied to the end portion of the heating element 14, the heating element 14 is attached to the electrode 20.

[0055] As a result, in the welding device 1, the electrical continuity between the electrode 20 and the heating element 14 is improved, so that a current corresponding to the voltage applied to the electrode 20 can be more reliably passed through the heating element 14.

[0056] Furthermore, instead of applying the conduction assist material 62 to the heating element 14, at least a portion of the resin constituting the fiber reinforced resin may be removed from the heating element 14 at the position where the electrode 20 is to be attached. For example, at least a portion of the fiber reinforced resin may be removed by scraping it off with a file or the like. Then, the electrode 20 may be attached to the end of the heating element 14 with at least a portion of the resin constituting the fiber reinforced resin removed.

[0057] In this embodiment as well, the electrical continuity between the electrode 20 and the heating element 14 is improved, so that a current corresponding to the voltage applied to the electrode 20 can be more reliably passed through the heating element 14 .

[0058] Furthermore, at least a portion of the resin constituting the fiber reinforced resin may be removed from the heating element 14 at the position where the electrode 20 is to be attached, and then the conduction assist material 62 may be applied. Then, the electrode 20 may be attached to the end of the heating element 14 in a state where at least a portion of the resin constituting the fiber reinforced resin has been removed and the conduction assist material 62 has been applied.

[0059] In this embodiment as well, the electrical continuity between the electrode 20 and the heating element 14 is improved, so that a current corresponding to the voltage applied to the electrode 20 can be more reliably passed through the heating element 14 .

[0060] 2, the current-carrying region is divided into two in the width direction of the heating element 14. However, the heating element 14 may have a current-carrying region divided into three or more parts. In other words, by providing three or more systems of electrodes 20 in the width direction of the heating element 14, the current-carrying region of the heating element 14 may be divided into three or more systems, the same number as the number of systems of electrodes 20.

[0061] 3 is a flowchart illustrating the flow of welding using the welding apparatus 1 of the first embodiment. To perform welding, first, the respective members are set (S10). For example, the first adherend 10, the second adherend 12, and the heating element 14 are each placed. An electrode 20 is attached to the end of the heating element 14. A pressure jig 42 is connected to the pressure device 24 and placed on the top surface of the second adherend 12. The electrode 20 is electrically connected to the power supply device 22. Note that the setting of the respective members may be performed by an operator or by a machine or device such as an industrial robot.

[0062] Next, the control device 30 sets a current profile (S11). The current profile includes, for example, the voltage value of the voltage to be applied to the electrodes 20 of each system, the timing to start applying the voltage, and the timing to end applying the voltage. Note that the current profile may also include the current value of the current to be passed through the electrodes 20, the timing to start passing the current, and the timing to end passing the current.

[0063] For example, when setting the current profile, the voltage value etc. is set according to parameters related to the adherends such as the material, shape and area to be welded of the first adherend 10 and the second adherend 12, and parameters related to the heating element 14 such as the material, resistance value and area to be welded of the heating element 14.

[0064] The energization profile may also include the pressure value of the pressure applied by the pressure device 24, the timing to start applying pressure, and the timing to end applying pressure.

[0065] For example, in the welding apparatus 1, pressure is applied by the pressure device 24 when the temperature of the heating element 14 is within a target temperature range. The target temperature range indicates the temperature range of the heating element 14 in which welding can be performed appropriately. Therefore, in the welding apparatus 1, the elapsed time from the start of current application until the target temperature range is reached is confirmed in advance by experiment or simulation for each combination of various parameters, and the start time of pressure application is specified based on the start of current application.

[0066] The upper limit of the target temperature range may be, for example, the temperature at which the resin of the heating element 14 changes its properties. The lower limit of the target temperature range may be any temperature at which welding can be performed appropriately. For example, it may be the melting point of the resin of the heating element 14, the glass transition temperature of the resin of the heating element 14, or a temperature that is a predetermined temperature lower than the glass transition temperature of the resin of the heating element 14. Pressurization may also be initiated before the target temperature range is reached. For example, the lower limit of the target temperature range may be the glass transition temperature of the resin of the heating element 14, and pressurization may be initiated when the temperature of the resin of the heating element 14 is below the glass transition temperature. By applying pressure when the temperature of the resin of the heating element 14 is below the glass transition temperature, welding can be initiated before the properties of the resin of the heating element 14 change, thereby preventing defects from occurring inside the welded first adherend 10 and second adherend 12.

[0067] In setting the energization profile, the pressurization start time and the like may be set according to the parameters related to the adherend and the parameters related to the heating element 14, for example.

[0068] After the energization profile is set, when a welding execution start condition is met, the control device 30 starts energization by causing the power supply device 22 to start applying voltage (S12). The welding execution start condition may be, for example, receiving an input instructing the start of welding execution, or arriving at a set energization start time.

[0069] When the control device 30 determines that a predetermined time has elapsed from the start of energization to the set start of pressurization, the control device 30 causes the pressurizing device 24 to start pressurizing (S13).

[0070] When the control device 30 determines that the pressurization time from the start of pressurization has exceeded the set predetermined time, it causes the power supply device 22 to stop applying voltage, thereby ending the current supply (S14).

[0071] In conjunction with the end of energization, the control device 30 causes the pressure device 24 to stop applying pressure (S15), thereby completing the welding of the first adherend 10 and the second adherend 12.

[0072] Fig. 4 is a diagram showing an example of the temperature transition of the heating element 14 when welding is performed by the welding device 1 of the first embodiment. A solid line C1 in Fig. 4 shows an example of the temperature transition of the first current-carrying region of the heating element 14. A dashed-dotted line C2 in Fig. 4 shows an example of the temperature transition of the second current-carrying region of the heating element 14.

[0073] Fig. 5 is a diagram showing an example of the transition of the voltage applied to the electrode 20 in the welding device 1 of the first embodiment. A solid line D1 in Fig. 5 shows an example of the transition of the first voltage applied between the positive first electrode 20a1 and the negative first electrode 20b1. A dashed-dotted line D2 in Fig. 5 shows an example of the transition of the second voltage applied between the positive second electrode 20a2 and the negative second electrode 20b2.

[0074] First, the first voltage and the first current flow region will be described. As shown in Fig. 5, when the first voltage of the first electrode increases from "0" to a predetermined voltage "V1," the first current flow region begins to flow, and the temperature of the first current flow region begins to increase, as shown in Fig. 4. After a predetermined time has elapsed since the start of current flow, the temperature of the first current flow region reaches the target temperature range.

[0075] The pressurization start time, based on the current application start time, is set to a time when pressurization starts after the temperature of the first current application region reaches the target temperature range. At the pressurization start time, pressurization by the pressurization device 24 begins, and while pressurization is being performed, the temperature of the first current application region is maintained within the target temperature range. When the time required for welding has elapsed from the pressurization start time, the first voltage is returned from "V1" to "0," and current application to the first current application region is terminated. After the current application end time, the temperature of the first current application region decreases due to natural heat dissipation, etc.

[0076] The first voltage "V1" is set to a voltage that can maintain the temperature of the first current-carrying region within the target temperature range during pressurization.

[0077] Next, the second voltage and the second current-carrying region will be described. As shown in Fig. 5, at the start of current-carrying, the second voltage of the second electrode is increased from "0" to a predetermined voltage "V2" in synchronization with the increase in the first voltage. The second voltage "V2" is set to a voltage that can maintain the temperature of the second current-carrying region within the target temperature range during pressurization.

[0078] Here, let us assume that the distribution of the resistance value of the heating element 14 is partially non-uniform due to variations in the fiber content distribution of the fiber-reinforced resin that constitutes the heating element 14. In this example, if a uniform potential is applied across the width of the heating element 14, the temperature distribution of the heating element 14 may change across the width of the heating element 14. This may cause the temperature of a portion of the heating element 14 across the width to fall outside the target temperature range.

[0079] 5, for example, the resistance value of the second current-carrying region of the heating element 14 is relatively higher than the resistance value of the first current-carrying region. In other words, it is relatively more difficult for current to flow in the second current-carrying region than in the first current-carrying region.

[0080] 5, the predetermined voltage "V2" of the second voltage for passing a current through the second current flow region is set to a value higher than the predetermined voltage "V1" of the first voltage, taking into consideration that a current flows less easily through the second current flow region than through the first current flow region. This makes it possible to maintain the temperature of the second current flow region within the target temperature range during pressurization, even if the resistance value of the second current flow region is higher than the resistance value of the first current flow region.

[0081] By applying such a voltage "V2" to the second electrode, the temperature transition in the second current-carrying region can be made substantially the same as the temperature transition in the first current-carrying region, as shown in FIG.

[0082] That is, the control device 30 causes the power supply device 22 to apply voltages individually to the electrodes 20 of each system so that the temperatures of the current-carrying regions of the heating element 14 become substantially uniform across the multiple current-carrying regions.

[0083] As a result, the welding device 1 can make the temperature distribution of the heating element 14 uniform during welding even if the distribution of the resistance value of the heating element 14 is uneven. As a result, the welding device 1 can prevent a decrease in welding quality.

[0084] Although the example described above is one in which the voltage of each system is controlled so that the temperatures of the multiple current-carrying regions are substantially uniform, the temperature control by the control device 30 is not limited to this example. For example, if the required temperature conditions are different between the first current-carrying region and the second current-carrying region, the temperatures of the respective current-carrying regions may be controlled to match the required temperature conditions, thereby making the temperatures of the respective current-carrying regions different.

[0085] Furthermore, in this embodiment, the timing of applying a voltage to the electrodes 20 in the first and second current-carrying regions is substantially the same, thereby allowing welding in the first and second current-carrying regions to be performed substantially simultaneously. However, the timing of applying a voltage to the electrodes 20 corresponding to the first and second current-carrying regions may be different. For example, welding in the first current-carrying region may be performed after welding in the second current-carrying region, or welding in the second current-carrying region may be performed after welding in the first current-carrying region. In other words, welding in the first and second current-carrying regions may be performed independently. This configuration can suppress mutual influence between the first and second current-carrying regions, such as when heat from the first current-carrying region is transferred to the second current-carrying region, causing the temperature of the second current-carrying region to deviate from the target temperature.

[0086] In this way, in the welding device 1 of the first embodiment, the heating element 14 is made of fiber-reinforced resin with fibers arranged in one direction. In the welding device 1 of the first embodiment, multiple systems of electrodes 20 are provided to divide the current-carrying area of ​​the heating element 14 in a direction intersecting the extension direction.

[0087] As a result, in the welding device 1 of the first embodiment, the width of the divided current-carrying regions is narrower than in an embodiment in which one current-carrying region is formed across the entire width of the heating element 14. Therefore, in the welding device 1 of the first embodiment, the influence of the distribution of resistance values ​​per current-carrying region is reduced.

[0088] Furthermore, in the welding device 1 of the first embodiment, since multiple systems of electrodes 20 are provided, it is possible to apply voltage to each current-carrying region. Therefore, in the welding device 1 of the first embodiment, it is possible to control the temperature for each current-carrying region, and it is possible to finely control the temperature distribution of the heating element 14.

[0089] Therefore, according to the welding device 1 of the first embodiment, even if there are portions in the heating element 14 where the distribution of resistance values ​​is uneven, it is possible to suppress a decrease in welding quality.

[0090] Second Embodiment Fig. 6 is a schematic diagram showing an example of the configuration of a welding device 100 according to a second embodiment. The welding device 100 of the second embodiment differs from the first embodiment in that it has a first heating element 141 and a second heating element 142 instead of the heating element 14, but other configurations are similar to those of the first embodiment. Therefore, in the second embodiment, differences from the first embodiment will be described, and descriptions of commonalities with the first embodiment will be omitted for convenience. Hereinafter, the first heating element 141 and the second heating element 142 may be collectively referred to as heating element 140.

[0091] In the first embodiment, a single heating element 14 is divided into a plurality of current-carrying regions. In contrast to this, in the second embodiment, a plurality of heating elements 140 themselves are provided, thereby dividing the current-carrying region.

[0092] The heating element 140 of the second embodiment is made of, for example, a fiber-reinforced resin such as carbon fiber reinforced plastic (CFRP). However, the heating element 140 of the second embodiment is not limited to a fiber-reinforced resin in which fibers are arranged in one direction, and may be, for example, a fiber-reinforced resin in which fibers are woven and arranged in multiple directions. Furthermore, the heating element 140 of the second embodiment is not limited to a fiber-reinforced resin, and may be made of any electrically conductive resin, any metal, any electrically conductive composite material, or the like.

[0093] The heating element 140 of the second embodiment corresponds to the heating element 14 of the first embodiment divided in half in the width direction. In other words, the width dimension of the heating element 140 is approximately half the width dimension of the heating element 14. Furthermore, the first heating element 141 and the second heating element 142 have roughly the same dimensions and shapes.

[0094] A positive first electrode 20a1 is attached to one end of the first heating element 141 in the extension direction. A negative first electrode 20b1 is attached to the other end of the first heating element 141 in the extension direction.

[0095] A positive second electrode 20a2 is attached to one end of the second heating element 142 in the extension direction. A negative second electrode 20b2 is attached to the other end of the second heating element 142 in the extension direction.

[0096] In this way, the first heating element 141 and the second heating element 142 are arranged side by side in the width direction of the heating element 140 and are disposed between the first adherend 10 and the second adherend 12 .

[0097] 7 is a plan view illustrating the current flowing through the heating element 140 in the second embodiment. The white arrows A10 and A12 in FIG. 7 indicate the direction in which the current flows.

[0098] As indicated by the outline arrow A10, a current corresponding to a first voltage applied between the positive first electrode 20a1 and the negative first electrode 20b1 flows through the first heating element 141. As indicated by a region B10, the first heating element 141 forms a first current-carrying region across the entire first heating element 141.

[0099] As indicated by the outline arrow A12, a current corresponding to the second voltage applied between the positive second electrode 20a2 and the negative second electrode 20b2 flows through the second heating element 142. As indicated by the region B12, the second heating element 142 forms a second current-carrying region throughout the second heating element 142.

[0100] In this way, in the welding device 100 of the second embodiment, a plurality of first heating elements 141 and second heating elements 142 are provided in the width direction of the heating element 140, so that the current-carrying region in the heating element 140, through which current flows, is divided in the width direction of the heating element 140. In the example of Fig. 7, the current-carrying region is divided into two, a first current-carrying region and a second current-carrying region, in the width direction of the heating element 140.

[0101] As a result, in the welding device 100, the temperature distribution of the heating element 140 can be controlled in accordance with the first voltage and the second voltage.

[0102] As shown in FIG. 7 , the first heating element 141 and the second heating element 142 are spaced apart from each other in the width direction, with a predetermined gap between the first heating element 141 and the second heating element 142. That is, adjacent heating elements 140 among the multiple heating elements 140 are insulated from each other by air, which is an insulator. Note that, for example, a solid insulator having insulating properties may be inserted into the gap between adjacent heating elements 140. Furthermore, insulating members 60, which are sheet-like insulators having insulating properties, are disposed between the positive-side first electrode 20a1 and the positive-side second electrode 20a2, and between the negative-side first electrode 20b1 and the negative-side second electrode 20b2. That is, adjacent heating elements 140 among the multiple heating elements 140 are insulated from electrical continuity by the insulating members 60, which are insulators.

[0103] This makes it possible to prevent an electrical short circuit between the first heating element 141 and the second heating element 142 in the welding device 100. As a result, the welding device 100 can appropriately divide the first current-carrying region of the first heating element 141 and the second current-carrying region of the second heating element 142.

[0104] As in the first embodiment, a conduction assisting material 62 that assists electrical conduction between the electrode 20 and the heating element 140 is applied to the position of the heating element 140 where the electrode 20 is attached. The conduction assisting material 62 is, for example, silver paste or plating. After the conduction assisting material 62 has been applied to the end portion of the heating element 140, the heating element 140 is attached to the electrode 20.

[0105] Furthermore, similarly to the first embodiment, instead of applying the conduction assist material 62 to the heating element 140, at least a portion of the resin constituting the fiber reinforced resin may be removed at the position where the electrode 20 is attached to the heating element 140. Then, the electrode 20 may be attached to the end of the heating element 140 with at least a portion of the resin constituting the fiber reinforced resin removed.

[0106] Furthermore, similarly to the first embodiment, at least a portion of the resin constituting the fiber reinforced resin may be removed from the heating element 140 at the position where the electrode 20 is to be attached, and then the conduction assist material 62 may be applied. Then, the electrode 20 may be attached to the end of the heating element 140 in a state where at least a portion of the resin constituting the fiber reinforced resin has been removed and the conduction assist material 62 has been applied.

[0107] 7, in the region to be welded, two heating elements 140 divide the current-carrying region into two in the width direction of the heating elements 140. However, three or more heating elements 140 may be provided in the region to be welded, forming a current-carrying region divided into three or more parts. In this case, three or more systems of electrodes 20 are provided, the same number as the number of heating elements 140, and one system of electrodes 20 is provided for each heating element 140.

[0108] In addition, the control device 30 in the welding device 100 of the second embodiment causes the power supply device 22 to apply voltage individually to the electrodes 20 of each heating element 140 so that the temperature of the heating elements 140 is substantially uniform across the multiple heating elements.

[0109] As a result, welding device 100 can make the temperature distribution of heating element 140 uniform during welding even if the distribution of resistance values ​​of heating element 140 is uneven. As a result, welding device 100 can prevent deterioration in welding quality.

[0110] In addition, when the required temperature conditions are different between the first current-carrying area and the second current-carrying area, the temperature control by the control device 30 may be such that the temperatures of each current-carrying area are different by controlling the temperature of each current-carrying area to match the required temperature conditions.

[0111] Furthermore, here, by applying a voltage to the electrodes 20 of the first heating element 141 (i.e., the first current-carrying region) and the second heating element 142 (i.e., the second current-carrying region) at substantially the same timing, welding in the first current-carrying region and welding in the second current-carrying region are performed substantially simultaneously. However, the timing of applying a voltage to the electrodes 20 of the first heating element 141 and the timing of applying a voltage to the electrodes 20 of the second heating element 142 may be different. As a result, for example, welding in the first current-carrying region may be performed first, followed by welding in the second current-carrying region, or welding in the second current-carrying region may be performed first, followed by welding in the first current-carrying region. In other words, welding in the first current-carrying region and welding in the second current-carrying region may be performed independently. In this aspect, it is possible to suppress mutual influence between the first current-carrying region and the second current-carrying region, such as when heat from the first current-carrying region is transferred to the second current-carrying region, causing the temperature of the second current-carrying region to deviate from the target temperature.

[0112] In this way, in the welding device 100 of the second embodiment, the plurality of heating elements 140 are arranged spaced apart from one another. Then, in the welding device 100 of the second embodiment, the electrodes 20 are attached to the plurality of heating elements 140 individually. That is, in the welding device 100 of the second embodiment, a plurality of current-carrying regions are formed, the number of which is the same as the number of heating elements 140.

[0113] As a result, in the welding device 100 of the second embodiment, the width of the divided current-carrying regions in the welding region is narrower than in an embodiment in which a single current-carrying region is formed across the entire width of the welding region, and therefore, in the welding device 100 of the second embodiment, the influence of the distribution of resistance values ​​per current-carrying region is reduced.

[0114] Furthermore, in the welding device 100 of the second embodiment, since multiple systems of electrodes 20 are provided, it is possible to apply voltage to each heating element 140, i.e., each current-carrying region. Therefore, in the welding device 100 of the second embodiment, it is possible to control the temperature for each current-carrying region, and it is possible to finely control the temperature distribution of the heating element 140 in the region to be welded.

[0115] Therefore, according to the welding device 100 of the second embodiment, it is possible to suppress a decrease in the welding quality in the region to be welded.

[0116] Although the embodiments have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

[0117] For example, the features of the first embodiment and the features of the second embodiment may be combined as appropriate.

[0118] REFERENCE SIGNS LIST 1, 100 welding device 10 first adherend 12 second adherend 14, 140 heating element 20 electrode 22 power supply device 24 pressure device

Claims

1. A welding device comprising: a heating element made of fiber-reinforced resin with fibers arranged in one direction, and arranged between a first adherend and a second adherend; multiple systems of electrodes attached to the heating element and dividing an electrical current area in the heating element in a direction intersecting the extension direction of the fibers; a power supply unit that applies a voltage to the electrodes to pass a current in the heating element in the extension direction; and a pressure device that applies pressure to at least one of the first adherend and the second adherend in a direction in which the first adherend and the second adherend approach each other when the heating element is heated by the current flowing through it, thereby welding the first adherend and the second adherend via the heating element.

2. The welding device according to claim 1, wherein the electrodes of adjacent systems among the electrodes of the plurality of systems are insulated from each other by an insulator.

3. The welding apparatus according to claim 1, wherein a conductivity assisting material for assisting electrical conduction between the electrodes and the heating element is applied to the heating element at the positions where the electrodes are attached.

4. The welding device according to claim 1, wherein the electrodes are attached to the heating element with at least a portion of the resin constituting the fiber reinforced resin removed from the position of the heating element where the electrodes are attached.

5. A welding apparatus as claimed in any one of claims 1 to 4, further comprising a control device for controlling the power supply device and the pressure device, wherein the control device causes the power supply device to apply voltages individually to the electrodes of each system so that the temperatures of the current-carrying regions in the heating element are substantially uniform in the multiple current-carrying regions.

6. A welding apparatus comprising: a plurality of heating elements spaced apart from each other and disposed between a first adherend and a second adherend; electrodes individually attached to the plurality of heating elements; a power supply unit which applies a voltage to the electrodes to pass an electric current through the heating elements; and a pressure device which, when the heating element is heated by the electric current flowing through it, applies pressure to at least one of the first adherend and the second adherend in a direction in which the first adherend and the second adherend approach each other, thereby welding the first adherend and the second adherend via the heating elements.

7. The welding device according to claim 6, wherein adjacent ones of the plurality of heating elements are insulated from each other by an insulator.

8. The welding apparatus according to claim 6 or 7, further comprising a control device for controlling the power supply device and the pressure device, wherein the control device causes the power supply device to apply voltages individually to the electrodes of each of the heating elements so that the temperatures of the heating elements are substantially uniform among the plurality of heating elements.

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