Spot welding machine

Abstract

The present invention provides a spot welding machine that does not require support to hold the workpiece in place when using a horizontal gun and requiring two-handed operation. [Solution] When the switch 450 is turned ON, the supply of compressed air to the gripper 44 is cut off, allowing the shaft 42 to move freely in the vertical direction. When the switch is turned OFF, the supply of compressed air to the gripper 44 is enabled, preventing the shaft 42 from moving vertically. When welding two workpieces, the contact device 46 is brought above the two workpieces and brought into contact with the upper workpiece, after which the switch 450 is turned OFF. This supplies compressed air to the gripper 44, causing the gripper 44 to hold the shaft 42 and press down on the two workpieces. By pressing down on the two workpieces, it becomes possible to weld both workpieces even when holding the horizontal gun with both hands.

Description

Technical Field

[0001] The present invention relates to a spot welding machine provided with a table electrode.

Background Art

[0002] Spot welding is a process in which at least two metal workpieces to be welded (for example, metal plates) are overlapped, the welding location is sandwiched between two electrodes, and current is passed while applying pressure to connect the workpieces with Joule heat generated at the welding location.

[0003] As a welding machine for performing spot welding, there is a table-type spot welding machine (see Patent Document 1) applied by the applicant. This spot welding machine includes a flat table electrode on which the workpieces to be welded are placed, and a horizontal gun that can move in a horizontal orientation parallel to the table electrode.

[0004] In this spot welding machine, for example, when connecting two metal workpieces to be welded, the workpieces to be welded are overlapped, the welding location (the location targeted for welding) is sandwiched between the table electrode and the horizontal gun, and current is passed while applying pressure. As a result, the two workpieces to be welded are connected by Joule heat generated at the welding location. Although this spot welding machine only has a horizontal gun, there are also those that only have a vertical gun or those that have both a horizontal gun and a vertical gun.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, since a horizontal welding gun can be operated with one hand, one can hold the gun with one hand and hold the workpiece with the other. However, if both hands are required to operate the horizontal welding gun, support is needed to hold the workpiece. Thus, when both hands are required to operate the horizontal welding gun, work efficiency decreases.

[0007] Incidentally, with a vertical welding gun, the operation involves lifting and lowering it vertically, making it difficult to operate with one hand, and assistance is needed to hold the workpiece in place.

[0008] This invention was made in view of the above circumstances, and aims to provide a spot welding machine that does not require support to hold down the workpiece when two-handed operation is required with a horizontal gun. [Means for solving the problem]

[0009] The spot welding machine of this invention is made of a conductive metal material and comprises a flat plate-shaped table electrode, a horizontal gun supported so as to be able to move up and down in a direction perpendicular to the planar direction of the table electrode, a support post erected perpendicular to the mounting surface of the device, a long, strip-shaped articulated arm having an articulation mechanism at least at both ends and in the center that rotates in the same direction as the planar direction of the table electrode, a plate to which one of the two ends of the articulated arm is attached to the support post, a cylindrical bush attached to the other end of the articulated arm in a direction perpendicular to the longitudinal direction of the articulated arm, and a long cylindrical shape with an outer diameter less than the inner diameter of the bush, The device comprises a shaft inserted into a bush, a gripper positioned close to the bush and gripping the shaft with compressed air, a rod-shaped handle positioned perpendicular to the length of the shaft at the end of the shaft closest to the mounting surface of the device, a switch provided on the handle that connects an input port and an output port when turned on and disconnects the connection between the input port and the output port when turned off, and a contactor positioned near the handle at the end of the shaft closest to the mounting surface of the device, wherein when the switch is turned off, the compressed air flows towards the gripper, and when the switch is turned on, the compressed air does not flow towards the gripper.

[0010] According to the above configuration, when the switch is turned on, the supply of compressed air to the gripper is cut off, allowing the shaft to move freely in the vertical direction. When the switch is turned off, the supply of compressed air to the gripper is enabled, preventing the shaft from moving in the vertical direction.

[0011] When welding two workpieces together, the contact device is brought above the two workpieces, brought into contact with the upper workpiece, and then the switch is turned off. This supplies compressed air to the gripper, causing it to hold the shaft and press down on the two workpieces. By pressing down on the two workpieces, it becomes possible to weld them together even while holding the horizontal gun with both hands.

[0012] Thus, even when it is impossible to stably place these workpieces on the table electrode, such as when operating a horizontal gun that requires two-handed operation or a vertical gun that requires two-handed operation, these workpieces can still be welded. [Effects of the Invention]

[0013] According to this invention, even when it is impossible to stably place two workpieces on the table electrode, such as when operating a horizontal gun that requires two-handed operation or when operating a vertical gun, these workpieces can be welded. [Brief explanation of the drawing]

[0014] [Figure 1] Side view showing the schematic configuration of a spot welding machine according to one embodiment of the present invention. [Figure 2] Figure 1 shows a schematic configuration of the power supply unit of a spot welding machine. [Figure 3] Figure 1 is a side view showing the workpiece holding jig for a spot welding machine. [Figure 4] Figure 1 is a plan view showing the workpiece holding jig for a spot welding machine. [Figure 5] Figure 1 shows a side view of the holding mechanism of the workpiece holding jig for a spot welding machine. [Figure 6] Figure 1 is a plan view showing the range of motion of the workpiece holding jig for the spot welding machine. [Figure 7] Schematic diagram illustrating the flow of compressed air in the switch of the workpiece holding jig of the spot welding machine (Figure 1). [Modes for carrying out the invention]

[0015] Hereinafter, preferred embodiments for carrying out the present invention will be described in detail with reference to the drawings. Figure 1 is a side view showing the schematic configuration of the spot welding machine 100 of the present invention. In the figure, the spot welding machine 100 comprises a cooling unit 102, a power supply unit 103, a support post 104, a support arm 105, a horizontal gun 108, a conductive cable 109, a table electrode 110, and a table drive unit 111. The cooling unit 102 supplies cooling water to cool the heat generated from the horizontal gun 108 during welding, and operates continuously while the power is on, circulating the water between the horizontal gun 108 and the cooling unit. The power supply unit 103 converts three-phase AC power supplied from the power receiving equipment 50 (see Figure 2) into DC power using a rectifier 31 and a capacitor 32 (both see Figure 2), and generates high-frequency AC power from the converted DC power.

[0016] The support post 104 is positioned near the cooling unit 102, erected perpendicular to the mounting surface of the equipment (spot welding machine 100). The support post 104 supports the support arm 105 so that it can rotate horizontally (the horizontal direction is defined as the direction perpendicular to the direction in which the support post 104 is erected). The support arm 105 is a cantilevered multi-joint arm and comprises horizontal arm sections 105A and 105B that extend horizontally relative to the support post 104, a pivot shaft 105C that connects the horizontal arm sections 105A and 105B so that they can rotate horizontally, and a pivot shaft 105D that supports the horizontal gun 108 at the tip of the horizontal arm section 105B so that it can rotate horizontally.

[0017] The gun bracket 140 of the horizontal gun 108 is formed in a substantially L shape with the lower end portion 140A bent, and supports the gun body 120 at this portion. The upper end portion 140B of the gun bracket 140 is attached to the rotation shaft 105D. The horizontal gun 108 includes, in addition to the gun bracket 140 described above, a pressure cylinder 130 and the gun body 120 described above. The pressure cylinder 130 is attached to the upper end of the rotation shaft 105D and rotates together with the gun bracket 140 by the rotation shaft 105D. The pressure cylinder 130 pulls up the gun body 120 via a chain (not shown). The chain is housed in the gun bracket 140. One end of the chain is connected to the piston rod (not shown) of the pressure cylinder 130, and the other end is connected to the gun body 120 via a chain hook (not shown).

[0018] A spring coil 142 is stretched between the rear end portion of the gun body 120 and the lower end portion of the gun bracket 140. The spring coil 142 biases the rear end portion side of the gun body 120 to lift upward. The gun body 120 moves up and down in the vertical direction due to the expansion and contraction of the spring coil 142.

[0019] A handle 121 that is manually operated by an operator is provided at the rear end of the gun body 120, enabling the vertical movement operation of the horizontal gun 108. A switch 35 (see FIG. 2) for outputting a welding command is provided on the handle 121, and a welding command is output by turning on the switch 35. The welding command output from the switch 35 is taken into the power supply unit 103. The power supply unit 103 starts operating by taking in the welding command and outputs high-frequency alternating current. The high-frequency alternating current output from the power supply unit 103 flows through the primary side coil of the welding transformer 38 (see FIG. 2). Note that the table electrode 110 is connected to one electrode side of the power supply unit 103, and the gun body 120 is connected to the other electrode side.

[0020] In FIG. 1, the conductive cable 109 electrically connects the power supply unit 103 and the horizontal gun 108. The high-frequency alternating current generated by the power supply unit 103 flows through the conductive cable 109 to the horizontal gun 108 side. The table electrode 110 is for placing the welded member (work W) and is formed in a flat plate shape. The table electrode 110 is mainly made of a copper plate (a metal material having conductivity such as copper). The table electrode 110 is disposed in a direction (i.e., the horizontal direction) orthogonal to the height direction of the housing of the spot welder 100 as a part of the housing. The table drive unit (vertical movement mechanism) 111 moves the table electrode 110 in the vertical direction (i.e., the vertical direction).

[0021] Next, the power supply unit 103 will be described. In FIG. 2, the power supply unit 103 generates a welding current from the direct current obtained by rectifying three-phase alternating current, and includes a rectifier 31, a smoothing capacitor 32, a welding control circuit 33, and an inverter circuit 34. The rectifier 31 adopts a single-phase full-wave rectification type and rectifies the three-phase alternating current from the power receiving equipment 50 to convert it into direct current. The welding control circuit 33 controls the magnitude and energization time of the welding current. The welding control circuit 33 is configured using, for example, a microcomputer. This microcomputer holds a program for welding control and operates according to the program.

[0022] The welding control circuit 33 detects a welding command from a switch 35 provided in the horizontal gun 108, generates a timing signal according to the material and thickness of the welded member set by the welding condition setter 36, and outputs it to the inverter circuit 34. The inverter circuit 34 includes an inverter control unit 341, four switches S1 to S4 using IGBT (Insulated Gate Bipolar Transistor), and a current sensor 342 using a CT (Current Transformer).

[0023] The inverter control unit 341 generates high-frequency alternating current by controlling the on / off state of switches S1 to S4 based on the timing signal generated by the welding control circuit 33 and the primary current detected by the current sensor 342. The magnitude of the high-frequency alternating current generated by the inverter control unit 341 changes depending on the on / off duty cycle of switches S1 to S4. When the high-frequency alternating current is output from the inverter circuit 34, a primary current flows through the primary coil of the welding transformer 38. The horizontal gun 108 is connected to the secondary coil of the welding transformer 38.

[0024] Next, the welded member holding jig 1 will be described with reference to Figures 3 to 5. Figure 3 is a side view showing the welded member holding jig 1 of the spot welding machine 100, Figure 4 is a top view showing the welded member holding jig 1 of the spot welding machine 100, and Figure 5 is a side view showing the holding mechanism 4 of the welded member holding jig 1 of the spot welding machine 100. In Figures 3 to 5, the welded member holding jig 1 comprises a multi-joint arm 2, an air tube 3, and a holding mechanism 4. The multi-joint arm 2 consists of two arms: a first arm 21 and a second arm 22. One end of the first arm 21 is connected to a support post 104, and the other end is connected to one end of the second arm 22. The first arm 21 is attached to the support post 104 via a plate 9. The holding mechanism 4 is connected to the other end of the second arm 22.

[0025] Plate 9 and one end of the first arm 21 are connected via a bearing 7. The first arm 21 is rotatable horizontally by the bearing 7. Note that the horizontal direction referred to here is perpendicular to the direction in which the support post 104 is erected. The other end of the first arm 21 and one end of the second arm 22 are connected via a bearing 8. The second arm 22 is rotatable horizontally by the bearing 8.

[0026] A bush 41 of the retaining mechanism 4 is provided at the other end of the second arm 22. The bush 41 is cylindrical with open ends and an inner diameter slightly larger than the outer diameter of the shaft 42. The bush 41 restricts the movement of the shaft 42 so that it moves up and down perpendicular to the articulated arm 2. That is, the shaft 42 moves only in the axial direction of the bush 41. The air tube 3 is a tube for supplying compressed air to the retaining mechanism 4 and is arranged along the plate 9, the first arm 21 and the second arm 22. The air tube 3 is composed of several short air tubes 3-1, 3-2, 3-3, 3-4, 3-5, and 3-6 connected in series. In particular, longer air tubes are used for the movable parts of the bearings 7 and 8 (the inverted U-shaped parts) and the part where the retaining mechanism 4 is located. The compressed air is supplied from a compressed air supply device (not shown). This device is connected to one end of air tube 3-1.

[0027] The clamping mechanism 4 comprises an air tube 43, a shaft 42, a bush 41, a gripper 44, a handle 45, and a contactor 46. One end of the air tube 43 is connected to the other end of the air tube 3, and the other end is connected to the gripper 44 via the handle 45. The handle 45 is used to operate the workpiece clamping jig 1, and the worker operates the clamping mechanism 4 by holding the handle 45. Figure 6 is a plan view showing the range of motion of the workpiece clamping jig 1. As shown in the figure, the clamping mechanism 4 can be freely moved within a range 200 of approximately 180 degrees with the length of the articulated arm 2 as the radius.

[0028] The handle 45 is equipped with a pneumatic switch 450. The switch 450 is a mechanical switch that turns "on" when pressed and "off" when released. The switch 450 is positioned between the compressed air supply side and the gripper 44 side, and stops or releases the flow of air from the compressed air supply side. That is, turning the switch 450 "on" causes compressed air to flow to the gripper 44 side, and turning it "off" prevents compressed air from flowing to the gripper 44 side. The switch 450 has an input port 451 (see Figure 7) and an output port 452 (see Figure 7). The air tube 43 on the compressed air supply side is connected to the input port 451, and the air tube 43 on the gripper 44 side is connected to the output port 452. There is an opening / closing mechanism (not shown) between the input port 451 and the output port 452. Pressing the switch 450 connects the input port 451 and the output port 452, and releasing the switch 450 disconnects the connection between the input port 451 and the output port 452.

[0029] Figure 7 is a schematic diagram showing the flow of compressed air at switch 450. When switch 450 is turned on, the compressed air is shut off and no longer flows towards gripper 44. As a result, gripper 44 can no longer hold the shaft 42, and the shaft 42 falls due to its own weight. In this state, when switch 450 is turned off, compressed air flows through switch 450 towards gripper 44, and gripper 44 holds the shaft 42. Arrow Y indicates the flow of compressed air at this time. Note that a locking device 47 is provided at the upper end of the shaft 42 to prevent it from falling out even if it falls due to its own weight.

[0030] The contact device 46 has a roughly cylindrical shape and is positioned below the handle 45 at the tip portion (i.e., the lower end portion) of the shaft 42. A cylindrical elastic member (for example, a "rubber member") 461 is provided at the tip portion of the contact device 46.

[0031] Now, when two-handed operation is required with the horizontal gun 108, the contactor 46 of the workpiece holding jig 1 is brought above the workpieces 150 and 151 (see Figure 5) and brought into contact with the workpiece located on the upper side (for example, workpiece 151). When bringing the contactor 46 above the workpieces 150 and 151, the switch 450 on the handle 45 is kept in the ON position. By keeping the switch 450 in the ON position, the gripper 44 cannot hold the shaft 42 while it is in that state, so the shaft 42 remains in the lowered position.

[0032] The contact device 46 is brought above the welded members 150 and 151, and after bringing it into contact with the upper welded member 151, the switch 450 is turned off. This restarts the supply of compressed air to the gripper 44, causing the gripper 44 to hold the shaft 42 and press down on the welded members 150 and 151. By pressing down on the welded members 150 and 151, welding can be performed even while holding the horizontal gun 108 with both hands. Note that the welded members 150 and 151 shown in Figure 5 are flat and do not require any special pressing, but if their shapes make stable welding impossible without pressing, stable welding can be performed by using the welded member pressing jig 1.

[0033] As described above, the spot welding machine 100 according to this embodiment includes a table electrode 110 made of a conductive metal material and having a flat plate shape, a horizontal gun 108 supported so as to be able to move up and down in a direction perpendicular to the planar direction of the table electrode 110, a support post 104 positioned to stand perpendicular to the mounting surface of the spot welding machine body, a multi-joint arm 2 having a long strip shape and having joint mechanisms at least at both ends and in the center that rotate in the same direction as the planar direction of the table electrode 110, a plate 9 to which one end of the multi-joint arm 2 is attached to the support post 104, a bush 41 having a cylindrical shape and attached to the other end of the multi-joint arm 2 in a direction perpendicular to the longitudinal direction of the multi-joint arm 2, a shaft 42 having an outer diameter less than the inner diameter of the bush 41 and being inserted into the bush 41, and The system includes a gripper 44 positioned close to the shaft 41 and gripping the shaft 42 when compressed air is supplied to it, a rod-shaped handle 45 positioned perpendicular to the length of the shaft 42 on the end of the shaft 42 closer to the mounting surface of the spot welding machine 100, a switch 450 provided on the handle 45 that connects the input port and output port when turned ON and disconnects the connection between the input port and output port when turned OFF, and a contact device 46 positioned near the handle 45 on the end of the shaft 42 closer to the mounting surface of the spot welding machine 100. When the switch 450 is turned OFF, compressed air supplied from the spot welding machine 100 is directed towards the gripper 44, and when the switch 450 is turned ON, compressed air supplied from the spot welding machine is not directed towards the gripper 44.

[0034] When switch 450 is turned ON, the supply of compressed air to the gripper 44 is cut off, allowing the shaft 42 to move freely in the vertical direction. When switch 450 is turned OFF, compressed air is supplied to the gripper 44, preventing the shaft 42 from moving vertically. Therefore, when welding two workpieces 150 and 151 together, the contact device 46 is brought above the two workpieces 150 and 151, brought into contact with the upper workpiece 151, and then the switch 450 is turned OFF. This supplies compressed air to the gripper 44, causing the gripper 44 to hold the shaft 42 and press down on the two workpieces 150 and 151. By pressing down on the two workpieces 150 and 151, it is possible to weld them together even while holding the horizontal gun with both hands. Therefore, even when operating a horizontal gun 108 that requires two-handed operation, or a vertical gun (not shown) that requires two-handed operation, and it is impossible to place these workpieces 150 and 151 stably on the table electrode 110, these workpieces 150 and 151 can still be welded.

[0035] In this embodiment, a support post 104 was used to support the welded member holding jig 1, but it is not limited to this, as long as it is part of a resistance welding machine, has a shape that protrudes vertically in a direction perpendicular to the installation surface, and has strength to support the weight of the articulated arm. [Industrial applicability]

[0036] This invention can be applied to a spot welding machine having a table electrode and a horizontal gun. [Explanation of symbols]

[0037] 1. Fixture for holding the member to be welded. 2. Multi-jointed arm 3,3-1,3-2,3-3,3-4,3-5,3-6,43 Air tube 4. Retaining mechanism 7,8 bearings 9 plates 21 First Arm 22. Second Arm 31 Rectifier 32 Smoothing Capacitors 33 Welding control circuit 34 Inverter Circuit 35 switches 36. Welding Condition Setting Device 38 Welding Transformer 41 Bush 42 shafts 44 Grip 45 handle 46 Abutment device 50 Power receiving equipment 100 Spot Welding Machine 102 Cooling Unit 103 Power Supply Unit 104 Support Posts 105 Support Arm 108 Horizontal Gun 109 Conductive Cable 110 Table electrodes 111 Table drive unit 150,151 Welded members 342 Current Sensor S1~S4, 450, 459 Switch

Claims

[Claim 1] It consists of a conductive metal material and a flat-plate shaped table electrode, A horizontal gun supported so as to be able to move up and down in a direction perpendicular to the planar direction of the table electrode, a support post positioned vertically perpendicular to the mounting surface of the device, and a long, strip-shaped component, At least the end portions and the central portion each have a multi-joint arm having a joint mechanism that rotates in the same direction as the planar direction of the table electrode, A plate for attaching one end of the multi-joint arm to the support post, A bushing having a cylindrical shape is attached to the other end of the articulated arm in a direction perpendicular to the longitudinal direction of the articulated arm, A shaft having an outer diameter less than the inner diameter of the bush, which is inserted into the bush, A gripper positioned in close proximity to the bush and gripping the shaft with compressed air, It is rod-shaped, and the part of the shaft closer to the mounting surface of the device has a handle positioned perpendicular to the length of the shaft, A switch is provided on the handle, which connects the input port and the output port when the switch is turned ON, and disconnects the connection between the input port and the output port when the switch is turned OFF. A contact device is positioned near the handle at the end of the shaft that is closer to the mounting surface of the device, Equipped with, When the switch is turned off, the compressed air is directed towards the gripper; when the switch is turned on, the compressed air is not directed towards the gripper. Spot welding machine.

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