JP5872226B2 - Spot welding equipment - Google Patents

Description

  The present invention relates to a spot welding apparatus for spot welding a member to be welded in a plate assembly in which plate materials are overlapped.

  In general, spot welding in which a pair of welding electrodes are sandwiched between a pair of welding electrodes and energized between the electrodes for a certain period of time is widely performed for joining the plate materials such as the stacked steel plates.

  Here, for example, as shown in FIG. 5A, a thin plate 101 having a low rigidity, a plate assembly in which three plate materials of a first thick plate 102 and a second thick plate 103 having higher rigidity than the thin plate 101 are stacked. When spot welding is performed on the member to be welded 100, when the member to be welded 100 is pressed by the movable side electrode 111 and the fixed side electrode 112, the thin plate 101 and the first thick plate 102 having low rigidity are moved upward. The bending causes a gap between the thin plate 101 and the first thick plate 102 and between the first thick plate 102 and the second thick plate 103. In this case, the contact area between the movable electrode 111 and the thin plate 101 is increased by the bending of the thin plate 101, whereas between the thin plate 101 and the first thick plate 102 and between the first thick plate 102 and the second thick plate 103. The contact area of the joint is reduced by the gap. For this reason, the current density between the movable side electrode 111 and the fixed side electrode 112 is higher on the second thick plate 103 side than on the thin plate 101 side, and the first thick plate 102 and the first thick plate 102 are larger than between the thin plate 101 and the first thick plate 102. The amount of heat generated locally between the two thick plates 103 increases.

  As a result, as shown in FIG. 5A, first, a nugget 105 is formed at a joint portion between the first thick plate 102 and the second thick plate 103, and the nugget 105 gradually becomes larger, and as shown in FIG. 5B. In this way, the thin plate 101 and the first thick plate 102 are welded. However, the amount of penetration between the thin plate 101 and the first thick plate 102 is small, the welding strength is unstable, and the welding quality varies. This problem is particularly noticeable as the first thick plate 102 and the second thick plate 103 are thicker and the nugget 105 is less likely to reach between the first thick plate 102 and the thin plate 101.

  As a countermeasure, for example, the spot welding method disclosed in Patent Document 1 spot-welds a three-layered member 100 to be welded of a thin plate 101, a first thick plate 102, and a second thick plate 103 as shown in FIG. Sometimes, the pressing force FU of the movable side electrode 125 on the thin plate 101 side is made smaller than the pressing force FL of the fixed side electrode 124 on the second thick plate 103 side, thereby joining the thin plate 101 and the first thick plate 102. The contact resistance of the first thick plate 102 and the second thick plate 103 decreases, and when the energization is performed between the movable side electrode 125 and the fixed side electrode 124, The amount of heat generated at the joint with the first thick plate 102 is increased, and the welding strength between the thin plate 101 and the first thick plate 102 is increased.

  As shown in FIG. 7, the spot welding apparatus used for carrying out this method has a spot welding apparatus 120 mounted on the wrist 116 of the welding robot 115. The welding robot 115 moves the spot welding device 120 to each spot position of the member to be welded 100 held by the clamper 118 to perform spot welding of the member to be welded 100.

  The spot welding device 120 includes a base portion 122 supported by a linear guide 121 fixed to a support bracket 117 attached to the wrist portion 116 so as to be movable up and down. The base portion 122 is provided with a fixed arm 123 extending downward. The fixed side electrode 124 is provided at the tip of the fixed arm 123.

  A pressure actuator 126 is mounted on the upper end of the base portion 122, and the movable side electrode 125 is attached to the lower end of the rod 127 that moves up and down by the pressure actuator 126 with respect to the fixed side electrode 124. A servo motor 128 is mounted on the upper end of the support bracket 117, and the base portion 122 moves up and down via the ball screw mechanism by the operation of the servo motor 128.

  Here, in accordance with teaching data stored in advance in a controller (not shown), the pressure FU applied by the movable electrode 125 located on the thin plate 101 side is made smaller than the pressure FL applied by the fixed electrode 124 (FU <FL).

  In order to make the pressure FU applied by the movable side electrode 125 smaller than the pressure applied FL by the fixed side electrode 124 in this way, the controller first raises the base portion 122 by the servo motor 128 to cause the fixed side electrode 124 to be welded. The movable electrode 125 is lowered by the pressure actuator 126 and brought into contact with the upper surface of the member 100 to be welded.

  Next, the base portion 122 is pushed up by the servo motor 128. As the base portion 122 is pushed up, the pressing force FL of the fixed side electrode 124 is increased by the pushing amount of the base portion 122, and the pressing force FU by the movable side electrode 125 becomes smaller than the pressing force FL by the fixed side electrode 124 (FU < FL).

  As a result, when the movable side electrode 125 and the fixed side electrode 124 are energized, the current density at the joint between the thin plate 101 and the first thick plate 102 is increased, and the amount of heat generated is the first thick plate 102 and the second thickness. It increases relative to the amount of heat generated at the joint of the plate 103. Thereby, a good nugget with no bias is formed from the thin plate 101 to the second thick plate 103, and the welding strength can be ensured.

JP 2003-251469 A

  According to Patent Document 1, the fixed side electrode 124 is brought into contact with the second thick plate 103 of the member to be welded 100 held by the clamper 118, the movable side electrode 125 is brought into contact with the thin plate 101, and the base portion 122 is further fixed. By pushing up and making the pressure FU on the movable electrode 125 side smaller than the pressure FL on the fixed electrode 124 side, the current density between the thin plate 101 and the first thick plate 102 becomes relatively high, and the thin plate 101 and the first plate The amount of heat generated at the joint with the thick plate 102 can be secured, the amount of penetration increases, and the welding strength increases.

  However, the member to be welded 100 held by the clamper 118 is moved between the base portion 122 in a state where the member to be welded 100 is sandwiched and pressed by the fixed side electrode 124 and the movable side electrode 125, and the movable side electrode 125 is moved by the pressing force FL of the fixed side electrode 124. In order to reduce the applied pressure FU, a large load is required on the clamper 118 that holds the member to be welded 100. On the other hand, in a state where the holding position of the member to be welded 100 by the clamper 118 and the welding position are largely separated from each other, the member to be welded 100 is bent and deformed, and the applied pressure FL by the fixed side electrode 124 and the applied pressure FU by the movable side electrode 125 vary. It is difficult to secure a stable contact resistance between the thin plate 101 and the first thick plate 102 and a contact resistance between the first thick plate 102 and the second thick plate 103 due to the occurrence of There is a concern that the quality of spot welding may deteriorate due to variations.

  Therefore, the objective of this invention made | formed in view of this point is providing the spot welding apparatus which can obtain the outstanding welding quality in carrying out the spot welding of the to-be-welded member of the board assembly which piled up the board | plate material.

The spot welding apparatus according to the first aspect of the present invention that achieves the above object includes a first welding electrode provided at a tip of a first arm, and a first welding electrode that is disposed to face the first welding electrode and cooperates with the first welding electrode. And a hydraulic cylinder having a second welding electrode provided on the second arm for sandwiching and pressing the member to be welded, a cylinder portion held by the first arm, and a rod protruding from the cylinder portion. the FukuKa pressure to said welding member abuts said to be welded member by a central axis direction the extended by-pressure imparting arm end the hydraulic cylinder provided in the first weld electrode from the rod A sub-pressurizing applying means having a sub- pressurizing portion to be applied, wherein the sub-pressurizing portion is adjacent to the welded member adjacent to the first welding electrode, and the subpressurizing force is applied to the welded member. A first sub-pressurizing position that applies A second sub-pressure position for applying the FukuKa pressure to said welding member abuts adjacent the second weld electrode, move the to a retracted position away from the weld member, wherein the workpiece to be welded those The member to be welded is sandwiched and pressurized by the first welding electrode and the second welding electrode that are in contact with each other, and the sub-pressurizing portion located at one of the first sub-pressing position and the second pressing position , Spot welding is performed by energizing between the first welding electrode and the second welding electrode in a sandwiched pressure state.

According to this, the member to be welded sandwiched and pressed by the first welding electrode and the second welding electrode is brought into contact with the first welding electrode adjacent to the first welding electrode by the auxiliary pressing portion at the first auxiliary pressing position. By applying pressure, the pressure applied by the first welding electrode becomes smaller than the pressure applied by the second welding electrode. Accordingly, a plate member having different rigidity, for example, a thin plate having low rigidity and a member to be welded in which the first thick plate and the second thick plate having high rigidity are overlapped and pressed with the thin plate as the first welding electrode side , When energized between the second welding electrode, the current density at the joint between the thin plate and the first thick plate is relatively increased, and excellent welding quality for the member to be welded is obtained.
Further, a sub-pressurizing force is applied to a member to be welded sandwiched and pressed between the first welding electrode and the second welding electrode by adjoining the second welding electrode by the sub-pressurizing portion at the second sub-pressurizing position. As a result, the pressure applied by the second welding electrode becomes smaller than the pressure applied by the first welding electrode. Accordingly, for example, the welded member in which the thin plate having low rigidity and the first thick plate and the second thick plate having high rigidity are overlapped and pressed with the thin plate as the second welding electrode side, the first welding electrode and the second welding electrode When the current is applied between the two, the current density at the joint between the thin plate and the first thick plate is relatively high, and excellent welding quality is obtained.

On the other hand, the sub-pressurization applying means having a sub-pressurization unit that moves at the retracted position, the first sub-pressurization position, and the second sub-pressurization position by the hydraulic cylinder held by the first arm and the hydraulic cylinder is configured and operated. It is simple, small and light, and the spot welding apparatus can be reduced in size and weight.

  According to a second aspect of the present invention, in the spot welding apparatus according to the first aspect, the first arm is a fixed arm provided with a first welding electrode at a tip, and the second arm is a second weld at the tip. It is a movable arm provided with an electrode.

Claim 2 is a specific example of the arrangement of sub-pressure applying means, it is intended to provide a sub-pressure applying means to the fixed arm.

  According to the present invention, the pressurizing force by the first welding electrode and the subpressing force from the sub-pressurizing portion are applied to the member to be welded, and the pressurizing force by the second welding electrode is applied to face the first welding electrode. The pressure applied by one welding electrode is smaller than the pressure applied by the second welding electrode. Thus, for example, when a member to be welded on which plate materials having different rigidity are stacked is pressed and energized between the first welding electrode and the second welding electrode, the joint of the thin plate and the first thick plate is relatively The current density is increased, and excellent welding quality for the member to be welded can be obtained.

  On the other hand, the auxiliary pressure applying means having the hydraulic cylinder disposed on the first arm and the auxiliary pressure portion that moves between the retracted position and the auxiliary pressure position by the hydraulic cylinder is small and lightweight, and the spot welding apparatus is reduced in size and weight. Is obtained.

It is a lineblock diagram of a spot welding device in an embodiment. It is the II section enlarged view of FIG. It is an operation | movement outline explanatory drawing of the spot welding apparatus typically shown. It is an operation | movement outline explanatory drawing of the spot welding apparatus typically shown. It is explanatory drawing which shows the outline | summary of the conventional spot welding. It is explanatory drawing which shows the outline | summary of the conventional spot welding. It is explanatory drawing which shows the outline | summary of the conventional spot welding.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a spot welding apparatus, FIG. 2 is an enlarged view of a portion II in FIG. 1, and FIGS. In the description of the spot welding apparatus, the upper and lower parts in FIG. 1 are referred to as the upper and lower parts in the spot welding apparatus for convenience.

  Prior to the description of the spot welding apparatus 1, the member to be welded 100 will be described. As shown in FIG. 2, a member 100 to be welded includes a thin plate 101 having a low rigidity, a first thick plate 102 having a thickness greater than that of the thin plate 101, and a third thick plate 103 each having a higher rigidity. Consists of.

  The configuration of the spot welding apparatus 1 will be described with reference to FIGS. 1 and 2.

  In the spot welding apparatus 1, a fixed arm 10, a pressure actuator 20 and a welding transformer 45 are mounted on a support bracket 3 attached to a wrist 51 of a welding robot 50 via an equalizer unit 2, and sub-pressure is applied to the fixed arm 10. Means 30 are provided.

  The fixed arm 10 is formed with a fixed arm body 11 having a base end coupled to the support bracket 3 and extending downward, and an electrode holding portion 12 extending in an L shape at the distal end of the fixed arm body 11. The fixed electrode 15 as the first welding electrode is attached to the tip of the electrode holding part 12 with the top end 15a facing upward.

  The pressurizing actuator 20 has a linear motion portion (not shown) constituted by a servo motor 21 and a ball screw mechanism, and the rod of the linear motion portion reciprocates up and down by the operation of the servo motor 21. A shaft-like movable arm 23 is provided at the lower end of the rod of the linear motion portion, and is coaxial with the fixed side electrode 15 provided on the fixed arm 10 at the tip of the electrode arm 23, that is, on the central axis L and the fixed side electrode 15. Oppositely, the movable side electrode 25 which is a 2nd welding electrode is provided. As a result, the movable side electrode 25 is moved upwardly away from the fixed side electrode 15 by the operation of the servo motor 21, and the welded member 100 is clamped in cooperation with the fixed side electrode 15 and the pressure is applied. It moves up and down along the central axis L between the applied pressure position. This applied pressure is determined by the rotational torque of the servo motor 21, and the desired applied pressure can be obtained by controlling the rotational torque of the servo motor 21.

  The auxiliary pressure applying means 30 has an auxiliary pressure applying actuator constituted by a hydraulic cylinder 31 disposed in the electrode holding portion 12 of the fixed arm 10, and the auxiliary pressure applying arm is provided via a rod 37 of the hydraulic cylinder 31. 38 is provided.

  The hydraulic cylinder 31 includes a cylindrical cylinder 33 held in a hollow cylindrical housing 13 formed in the electrode holding portion 12 and having a central axis parallel to the central axis L, and a pair of cylinders 33 sealed and sealed at both ends. The cylinder portion 32 includes a bottom surface portion 34 having a through hole 34a and a top surface portion 35 having a through hole 35a. A piston 36 that divides the inside of the cylinder portion 32 into a first hydraulic chamber 32A and a second hydraulic chamber 32B is incorporated, and a pair of rods that penetrate the through hole 34a of the bottom surface portion 34 and the through hole 35a of the top surface portion 35 into the piston 36. 37 is fixed. The hydraulic cylinder 31 is relatively small and light and can be easily disposed on the fixed arm 10 and can be widely used and configured with an existing hydraulic cylinder.

  An auxiliary pressure applying arm 38 extending perpendicular to the central axis L is provided at the top end of each rod 37 protruding from the top surface portion 35 of the cylinder portion 32. The auxiliary pressure applying arm 38 has a proximal end coupled to the top end of each rod 37, a distal end extending in the direction of the central axis L, and an auxiliary pressure applying portion 39 provided at the distal end. The sub-pressurizing unit 39 is coaxial with the central axis L, and has an upper end 39a and a lower end 39b protruding upward and downward from the tip of the sub-pressurizing application arm 34 and allowing the fixed side electrode 15 and the movable side electrode 25 to pass therethrough. It is formed in an arc shape, that is, a half cylinder shape.

  When the piston 36 of the hydraulic cylinder 31 moves to the lower ascending movement end indicated by the phantom line 36a in FIG. 2, the sub-pressurizing unit 39 provided at the tip of the sub-pressurizing application arm 38 coupled to the rod 37 becomes The upper end 39a moves to the first retreat position 39-1 that is below the top end 15 of the fixed electrode 15, and stops. On the other hand, when the piston 36 moves to the ascending movement end, the lower end 39b of the sub pressurizing portion 39 provided on the sub pressurizing application arm 38 is removed from the welded member 100 sandwiched between the fixed side electrode 15 and the movable side electrode 25. It moves to the 2nd retreat position 39-2 which leaves | separates upwards, and stops.

  On the other hand, the first hydraulic chamber 32A and the second hydraulic chamber 32B of the hydraulic cylinder 31 are supported by oil passages 41a and 41b formed through the fixed arm 10 and hydraulic switching valves and pressure control valves (not shown). 2 communicates with a hydraulic pump 40 or a tank serving as a hydraulic supply source mounted on the tank 2. That is, the first hydraulic chamber 32A is connected to the hydraulic pump 40 and the tank via the oil passage 41a via the hydraulic switching valve and the pressure control valve. On the other hand, the second hydraulic chamber 32B is connected to the hydraulic pump 40 and the tank via the oil passage 41b via the hydraulic switching valve and the pressure control valve.

  As a result, the pressure oil regulated from the hydraulic pump 40 by switching the hydraulic switching valve is supplied to the first hydraulic chamber 32A via the oil passage 41a and the like, and at the same time from the second hydraulic chamber 32B to the tank via the oil passage 41b. Discharge. The sub-pressurizing unit 39 provided at the tip of the sub-pressurizing application arm 39 coupled to the rod 37 is moved to the second retracted position by moving the piston 36 to the ascending movement end accompanying the hydraulic pressure supply to the first hydraulic chamber 32A. Move to 39-2 side and stop.

  In addition, the sub-pressurizing portion 39 is moved to the welded member 100 at a sub-pressurizing position where the sub-pressurizing portion 39 moving upward is sandwiched between the fixed side electrode 15 and the movable side electrode 25 and pressed against the welded member 100 from below. The auxiliary pressure Fα is applied from 39. The auxiliary pressure Fα is determined by the hydraulic pressure supplied to the first hydraulic chamber 32A and can be set by a pressure control valve.

  On the other hand, the pressure oil regulated from the hydraulic pump 40 by switching the hydraulic switching valve is supplied to the second hydraulic chamber 32B and simultaneously discharged from the first hydraulic chamber 32A to the tank through the oil passage 41a. As the hydraulic pressure is supplied to the second hydraulic chamber 32B, the piston 36 moves toward the lowering movement end side, whereby the sub-pressurizing portion 39 provided on the pressurizing arm 38 via the rod 37 is moved to the first retraction position 39-. Move to 1 and stop.

  In addition, the sub-pressurizing portion 39 is moved to the welded member 100 at a sub-pressurizing position where the sub-pressurizing portion 39 that moves downward is pressed against the welded member 100 sandwiched between the fixed electrode 15 and the movable electrode 25 from above. From the above, the auxiliary pressure Fα is applied.

  An output terminal of the welding transformer 45 serving as a power source is connected to the fixed side electrode 15 through the bus bar and the fixed arm 10 and the like, and the other output terminal is connected to the movable side electrode 25 through the bus bar and the electrode arm 23 and the like. Connect as possible.

  In addition, teaching data of the welding robot 50 is stored in a welding robot controller (not shown), and the teaching data includes an operation program for sequentially spot welding the welding spot positions of the member to be welded 100, and each welding spot, that is, the welding position. The position and attitude of the spot welding apparatus 1 in FIG. A welding controller (not shown) includes an operation program of the welding apparatus 1 and an operation control of the pressure actuator 20, the sub-pressurizing application means 30 and the welding transformer 45.

  In the spot welding apparatus 1 configured as described above, the auxiliary pressure applying means 30 including the hydraulic cylinder 31 and the auxiliary pressure applying arm 38 provided on the fixed arm 10 is configured to be relatively small and light, and the welding robot 50 can be easily attached to the wrist 51, and the load on the welding robot 50 can be suppressed without restricting the operation of the welding robot 50. Further, the sub-pressurizing application actuator for operating the sub-pressurizing application arm 34 is constituted by a hydraulic air cylinder 31 having a simple mechanism and relatively easy operation control, and the hydraulic pressure supply control in which the operation of the sub-pressurizing application means 30 is simple. You can do it.

  Next, the operation of the spot welding apparatus 1 will be described with reference to the operation outline explanatory diagrams of FIGS. For the convenience of explanation in this explanation, an example of spot welding a plate assembly in which the member to be welded 100 is laminated with the thin plate 101, the first thick plate 102, and the second thick plate 103 in order from the bottom will be described with reference to FIG. An example in which the member to be welded 100 is spot-welded to the plate assembly in which the thin plate 101, the first thick plate 102, and the second thick plate 103 are overlapped in order from the top will be described with reference to FIG.

  In spot welding of the member to be welded 100 in which the thin plate 101, the first thick plate 102, and the second thick plate 103 are stacked in order from the bottom, the movable side is operated by the servo motor 21 of the spot welding apparatus 1 according to a preset operation program. The electrode 25 is moved to the retracted position and held, and the hydraulic oil from the hydraulic pump 40 is supplied to the second hydraulic chamber 32A of the hydraulic cylinder 31 by switching the hydraulic switching valve and simultaneously drained from the first hydraulic chamber 32A. The sub-pressurizing unit 39 provided on the sub-pressurizing application arm 38 is moved to the first retreat position 39-1 by moving the piston 36 to the descending movement end, and is prepared.

  Next, the robot controller operates the welding robot 50 to bring the top end 15a of the fixed electrode 15 into contact with the striking point position, which is the welding position of the welded member 100, as shown in FIG. 1 is positioned.

  In a state where the spot welding apparatus 1 is positioned at the welding position, the top end 15a of the fixed side electrode 15 abuts on the thin plate 101 of the member to be welded 100 from below as shown in FIG. The top end 25a faces the second thick plate 103 with a gap, and the upper end 39a of the sub-pressing part 39 faces the thin plate 101 with a gap.

  Next, in a state where the fixed side electrode 15 is in contact with the thin plate 101 of the member 100 to be welded, the movable side electrode 25 is moved closer to the fixed side electrode 15 from the retracted position by the operation of the servo motor 21 of the pressure actuator 20. As shown in FIG. 3 (b), the member to be welded 100 is sandwiched between the fixed side electrode 15 and the movable side electrode 25 by moving in the pressure position direction and contacting the second thick plate 103 from above.

  Further, the servo motor 21 is operated until a predetermined torque is reached, and the movable side electrode 25 is pressed against the second thick plate 103. As a result, the pressurizing force of the pressure actuator 20 acts on the fixed side electrode 15 via the movable side electrode 25 and the fixed arm 10, and the welded part of the member 100 to be welded between the movable side electrode 25 and the fixed side electrode 15. And pressurizing.

  On the other hand, the sub-pressurizing application means 30 switches the hydraulic pressure switching valve to supply the pressure oil regulated by the hydraulic pump 40 to the first hydraulic chamber 32A and simultaneously discharge the oil from the second hydraulic chamber 32B. Along with the upward movement of the piston 36 due to the supply of hydraulic pressure to the first hydraulic chamber 32A, the sub-pressurizing portion 39 provided on the sub-pressurizing application arm 38 via the rod 37 moves from the first retraction position 39-1 to the upper end 39a. However, it moves to the thin plate 101 of the member to be welded 100 from the lower side adjacent to the fixed side electrode 15 to the sub pressurizing position, and the sub pressurizing portion 39 applies the sub pressurizing force Fα to the thin plate 101.

  In a state in which the member to be welded 100 is sandwiched and pressed by the fixed side electrode 15 and the movable side electrode 25 and the sub-pressurizing unit 39 applies the sub-pressurizing force Fα from below to the thin plate 101 adjacent to the fixed side electrode 15. As shown in FIG. 3C, the pressing force FU by the movable electrode 25 is applied to the second thick plate 103 from above, and the pressing force FL by the fixed electrode 15 and the sub pressing force Fα by the sub pressurizing unit 35 are thin plates. 101.

  In this case, as schematically shown in FIG. 3C, the pressure applied by the pressure actuator 20 acts on the movable electrode 25 and faces the movable electrode 25 via the fixed arm 10. On the other hand, the urging force of the hydraulic cylinder 31 in the sub-pressurizing application means 30 acts on the sub-pressurizing unit 39, and the pressing force FU and the thin plate 101 by the movable electrode 25 acting on the second thick plate 103 from above. Thus, the sum of the pressing force FL by the fixed side electrode 15 acting from below and the sub pressing force Fα by the sub pressurizing unit 39 becomes equal (FU = FL + Fα).

  As a result, a pressure FU is applied from the movable electrode 25 to the second thick plate 103 and a pressure FL from the fixed electrode 15 is applied to the thin plate 101 to the welded portion of the member 100 to be welded and a sub-pressurization. Since the auxiliary pressure Fα is applied from the portion 39, the applied pressure FL acting on the thin plate 101 from the fixed side electrode 15 is obtained by subtracting the auxiliary pressure Fα from the auxiliary pressure portion 39 from the applied pressure FU from the movable electrode 25. A pressing force is applied (FL = FU−Fα).

  In this way, the pressing force FL from the fixed electrode 15 acting on the thin plate 101 side is made smaller (FL <FU) than the pressing force FU of the movable electrode 25 acting on the second thick plate 103 side, so that the thin plate 101 and The contact pressure at the junction of the first thick plate 102 is smaller than the contact pressure between the first thick plate 102 and the second thick plate 103, and the contact resistance between the thin plate 101 and the first thick plate 102 is relatively increased. At the same time, the contact resistance between the first thick plate 102 and the second thick plate 103 is reduced.

  Next, the member 100 to be welded is sandwiched and pressed by the movable side electrode 25, the fixed side electrode 15 and the sub-pressurizing portion 39, and the pressing force FL of the fixed side electrode 15 located on the thin plate 101 side is changed to the second thick plate 103 side. The welding transformer 45 is energized for a predetermined time and welded between the movable transformer 25 and the fixed electrode 15 in a state where the applied pressure FU is lower than that of the movable electrode 25 positioned at the position. When the movable side electrode 25 and the fixed side electrode 15 are energized, the contact resistance between the thin plate 101 and the first thick plate 102 is relatively large, the current density is increased, and the first thick plate 102 is increased. And the second thick plate 103 are kept small in contact resistance. As a result, the amount of heat generated at the joint between the thin plate 101 and the first thick plate 102 is relatively increased with respect to the amount of heat generated at the joint between the first thick plate 102 and the second thick plate 103, and the second from the thin plate 101. Good welding without uneven current density is performed over the thick plate 103, and welding strength and welding quality can be ensured.

  After this welding is completed, the hydraulic pressure switch valve is switched to supply the hydraulic oil from the hydraulic pump 40 to the second hydraulic chamber 32A, and at the same time, drain the oil from the first hydraulic chamber 32A and move the piston 36 to the lowering movement end. The sub pressurization part 39 provided in the pressurization provision arm 38 is moved to the 1st retracting position 39-1. Further, the movable side electrode 25 is moved to the retracted position by the operation of the servo motor 21 of the pressurizing actuator 20 to release the member 100 to be welded between the fixed side electrode 15 and the movable side electrode 25.

  Thereafter, the welding robot 50 is operated according to the operation program, the spot welding apparatus 1 is retracted from the spot position of the welded member 100, and moved to the spot position of the next welded member 100.

  Next, spot welding of the member to be welded 100 in which the thin plate 101, the first thick plate 102, and the second thick plate 103 are overlaid in order from the top will be described with reference to FIG.

  When spot welding is performed on the member to be welded 100 in which the thin plate 101, the first thick plate 102, and the second thick plate 103 are overlaid in order from the top, the movable electrode 25 of the spot welding apparatus 1 is retracted according to a preset operation program. In addition, by supplying the hydraulic oil from the hydraulic pump 40 to the first hydraulic chamber 32A by switching the hydraulic switching valve, the oil is discharged from the second hydraulic chamber 32B, and the piston 36 is moved to the ascending movement end to move the auxiliary pressurizing arm. The sub pressurization part 39 provided in 38 is moved and hold | maintained to the 2nd retraction position 39-2.

  Next, the robot controller operates the welding robot 50 to bring the top end 15a of the fixed side electrode 15 into contact with the striking position as the welding position of the member to be welded 100 as shown in FIG. 1 is positioned.

  Next, as shown in FIG. 4B, the movable side electrode 25 is added from the retracted position by the operation of the servo motor 21 of the pressure actuator 20 with the fixed side electrode 15 in contact with the second thick plate 103. It is moved in the pressure position direction and brought into contact with the thin plate 101 from above. Further, the servo motor 21 is operated until a predetermined torque is reached, and the movable side electrode 25 is pressed against the thin plate 101. As a result, the pressurizing force of the pressurizing actuator 20 acts on the movable side electrode 25 and the fixed side electrode 15, sandwiching the welded portion of the welded member 100 between the movable side electrode 25 and the fixed side electrode 15 and pressurizing. .

  On the other hand, the sub-pressurizing application means 30 switches the hydraulic pressure switching valve to supply the pressure oil regulated from the hydraulic pump 40 to the second hydraulic chamber 32B and at the same time drain the oil from the first hydraulic chamber 32A. A sub-pressurizing portion 39 provided at the tip of the sub-pressurizing application arm 38 via the rod 37 as the piston 36 moves toward the descending movement end accompanying the supply of hydraulic pressure to the second hydraulic chamber 32B is provided in the second. From the retreat position 39-2, the lower end 39b moves from the upper side adjacent to the movable plate 25 to the thin plate 101 of the member to be welded 100 and moves from the upper side to the sub pressurizing position 39. Is granted.

  As a result, as shown in FIG. 4C, the pressing force FU by the movable side electrode 25 and the sub pressing force Fα of 39 are applied to the thin plate 101, and the pressing force FL by the fixed side electrode 15 is applied to the second thick plate 103. Is granted. As a result, the welding transformer 45 fixes the movable electrode 25 to the movable electrode 25 while the applied pressure FU of the movable electrode 25 positioned on the thin plate 101 side is smaller than the applied pressure FL of the fixed electrode 15 positioned on the second thick plate 103 side. A current is passed between the side electrode 15 and welding for a predetermined time.

  When the movable side electrode 25 and the fixed side electrode 15 are energized, the contact resistance between the thin plate 101 and the first thick plate 102 is relatively large, the current density is increased, and the first thick plate 102 is increased. And the second thick plate 103 are kept small, and the heat generation at the junction between the thin plate 101 and the first thick plate 102 is smaller than the heat generation at the junction between the first thick plate 102 and the second thick plate 103. By relatively increasing, good welding without uneven current density is performed from the thin plate 101 to the second thick plate 103, and the welding strength and the welding quality can be ensured.

  After this welding is completed, pressure oil is supplied from the hydraulic pump 40 to the first hydraulic chamber 32A by switching the hydraulic switching valve of the sub-pressurizing application means 30, and at the same time, the oil is discharged from the second hydraulic chamber 32B and the piston 36 is raised. The sub-pressurizing unit 39 provided on the sub-pressurizing application arm 39 is moved to the moving end and moved to the second retreat position 39-2. Further, the movable side electrode 25 is moved to the retracted position by the operation of the servo motor 21 of the pressurizing actuator 20 to release the sandwiched member 100 between the fixed side electrode 15 and the movable side electrode 25.

  Thereafter, the welding robot 50 is operated according to the operation program, the spot welding apparatus 1 is retracted from the spot position of the welded member 100, and moved to the spot position of the next welded member 100.

  According to this embodiment configured as described above, the sub-pressurizing force by the hydraulic cylinder 31 is applied to the member to be welded 100 which is pressurized by the fixed side electrode 15 and the movable side electrode 25, and the fixed side electrode 15 and the movable side The welding pressure for the member to be welded 100 in which the plate members having different rigidity are stacked by controlling the applied pressures FL and FU by the electrode 25 is improved.

  On the other hand, since a relatively small and light hydraulic cylinder 31 and a sub-pressurizing application means 38 configured to reciprocate by the hydraulic cylinder 31 are disposed on the fixed arm 10, a spot welding apparatus is provided. 1 can be reduced in size and weight without incurring an increase in size, and the position control of the spot welding apparatus 1 can be easily performed without increasing the weight on the distal end side of the fixed arm 10, and the operation control of the welding robot 50 can be simplified. The load on the welding robot 50 can be reduced. Further, when a plurality of welding robots are used, interference with other welding robots is reduced, and simultaneous work with other welding robots becomes possible, thereby improving work efficiency.

  Further, since the auxiliary pressure applying means 30 constituted by the hydraulic cylinder 31 and the auxiliary pressure applying arm 38 reciprocated by the hydraulic cylinder 31 is disposed on the fixed arm 10, the existing auxiliary pressure applying means 30 is provided. The spot welding apparatus has the same basic configuration as that of the spot welding apparatus, and the spot welding apparatus according to the present embodiment can be configured by replacing the fixed arm without greatly changing the conventional spot welding apparatus.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of invention. For example, in the above embodiment, the auxiliary pressure applying means 30 constituted by the auxiliary pressure applying arm 38 reciprocated by the hydraulic cylinder 31 is arranged on the fixed arm 10, but the movable arm 23 is replaced with the fixed arm 10. It can also be arranged. In the above embodiment, the hydraulic pump 40 or the like serving as a hydraulic pressure supply source is mounted on the support bracket 2 of the spot welding apparatus 1. However, the spot welding apparatus 1 can be reduced in size and weight by being disposed on the welding robot 50 side. Furthermore, the posture control of the spot welding apparatus 1 can be facilitated and the load on the welding robot 50 can be reduced.

DESCRIPTION OF SYMBOLS 1 Spot welding apparatus 10 Fixed arm 15 Fixed side electrode (1st welding electrode)
15a Top end 20 Pressurizing actuator 21 Servo motor 23 Movable arm 25 Movable electrode 30 Sub pressurizing application means 31 Hydraulic cylinder (sub pressurizing application actuator)
32 Cylinder part 38 Sub pressurizing application arm 39 Sub pressurizing part 39-1 First retraction position 39-2 Second retraction position 40 Hydraulic pump (hydraulic supply source)
50 welding robot 51 wrist 100 member to be welded

Claims (2)

A first welding electrode provided at the tip of the first arm;
A second welding electrode provided on a second arm that is disposed opposite to the first welding electrode and clamps and pressurizes a member to be welded in cooperation with the first welding electrode;
A hydraulic cylinder having a cylinder portion held by the first arm and a rod projecting from the cylinder portion; and a sub-pressurizing application arm extending from the rod in a central axis direction of the first welding electrode. Provided with a sub-pressurizing application means having a sub- pressurizing portion that is provided at a tip and abuts against the member to be welded by the hydraulic cylinder and applies a sub- pressurizing force to the member to be welded.
The sub-pressurizing portion abuts the member to be welded adjacent to the first welding electrode to apply a sub-pressurizing force to the member to be welded; 2 abutting adjacent to the welding electrode and moving to a second sub-pressurizing position for applying a sub-pressurizing force to the member to be welded, and a retreat position separating from the member to be welded,
The member to be welded includes a first welding electrode and a second welding electrode that are in contact with the member to be welded, and a sub-pressurizing portion located at one of the first sub-pressing position and the second pressure position. A spot welding apparatus characterized in that spot welding is performed by energizing between the first welding electrode and the second welding electrode in the clamping pressure state. The first arm is a fixed arm provided with a first welding electrode at a tip,
The spot welding apparatus according to claim 1, wherein the second arm is a movable arm having a second welding electrode provided at a tip thereof.

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