WO2000010767A1 - Resistance welding device - Google Patents

Abstract

A resistance welding device, wherein, when a motor (30) installed on a column (28) of a resistance welding device (10) is rotated and a clutch part (35) of a clutch brake mechanism (32) is engaged, a cylindrical groove cam (54) is rotated and its rotating motion is converted to a linear motion by a follower (60), whereby a pressing mechanism (13) is lowered together with an upper welding electrode (12) and objects to be welded (146, 148) are held between a lower welding electrode (14) and the upper welding electrode (12), the upper resistance electrode (12) is displaced relative to a body (76) of the pressing mechanism (13) when the pressing mechanism (13) is displaced further, its pressing force (P) is detected by a strain gauge and, when the pressing force (P) becomes equal to a pressing force setting value (P1), a welding current flows from a welding power supply (20) so as to weld the objects to be welded (146, 148).

Description

 Description Resistance welding equipment Technical field

 The present invention relates to a resistance welding apparatus that performs welding by bringing two types of workpieces into contact with each other and energizing the workpieces. Background art

 In resistance welding, two types of workpieces are brought into contact with each other and a current is applied while mechanically applying pressure, so that the contact resistance of the pressurized part between the workpieces and the contact of other metal parts The basic principle is that the resistance becomes lower than the resistance, the welding current is concentrated and Joule heat is generated, and as a result, a molten state of the metal part is obtained, which leads to welding together with the pressing force. In this case, the welding quality depends greatly on three factors: welding current, welding time and pressure.

 As a device for performing such resistance welding, for example, a device in which a movable electrode is brought close to a fixed electrode by a displacement mechanism such as an air cylinder, and an object to be welded is clamped and pressed by the movable electrode and the fixed electrode to perform welding. Are known.

 However, in the resistance welding apparatus according to the related art described above, for example, when an air cylinder is used as a displacement mechanism, the stop position of the movable electrode is determined so that welding can be performed with a predetermined pressing force. It is necessary to adjust the position of the spring and the length of the spring with high accuracy, which complicates the work.

 On the other hand, if a pulse motor is used for the displacement mechanism and the rotary motion of the pulse motor is converted into linear motion by a ball screw, the stop position accuracy of the movable electrode can be improved. However, there is a problem in that the cost of the resistance welding apparatus rises because of the high cost.

Moreover, in any of these methods, since the displacement of the movable electrode is converted into a pressing force, for example, the elasticity of a spring or the like that presses the movable electrode against the workpiece is applied. If the coefficient fluctuates over time or if the welding electrode is worn, it will not be possible to obtain an accurate pressing force. Therefore, these elements need to be constantly managed.

 However, at present, for example, it is assumed that a constant pressure is obtained after measuring the pressure at the start of work, adjusting the amount of displacement so that the pressure becomes a predetermined value, and so on. Therefore, it was not guaranteed that all the workpieces were welded with the desired welding quality, assuming that the pressure would fluctuate during the work.

 Therefore, a pressure detecting means for detecting the pressure applied to the workpiece by the movable electrode and the fixed electrode is connected to the displacement mechanism, and when the pressure reaches a predetermined value, the air cylinder or the pulse motor is stopped. There is a method that eliminates the need to manage the length of the welding electrode by performing welding by welding.

 However, when an air cylinder is used, the accuracy of the stop position of the movable electrode depends on the mounting position of the stop, and it is difficult to obtain a desired pressing force on the workpiece by the movable electrode and the fixed electrode. On the other hand, when a pulse motor is used, the pulse motor and the pole screw are expensive as described above, and the cost of the resistance welding apparatus rises.

 In addition, using a torque motor, the rotary motion is converted to linear motion to displace the movable electrode, and the movable electrode is pressed against the workpiece with a constant torque, thereby reducing the length of the welding electrode. It is possible to eliminate the need for management, but in this case, it is difficult to generate an accurate torque, and the pressing force of the movable electrode and the fixed electrode against the work to be welded varies, and welding quality is reduced. There is a problem that it cannot be kept constant.

 A general object of the present invention is to eliminate the necessity of controlling the length of a welding electrode and to perform welding by applying a desired pressing force to an object to be welded, thereby achieving a constant welding quality. An object of the present invention is to provide a resistance welding apparatus which can be obtained and can be manufactured at a low price.

The main object of the present invention is to maintain a constant pressurization regardless of the effects of mechanical aging. An object of the present invention is to provide a resistance welding device capable of applying force and performing optimum resistance welding.

 Another object of the present invention is to provide a resistance welding apparatus capable of constantly controlling the welding pressure during welding from the outside. Disclosure of the invention

 In order to achieve the above object, the present invention provides a resistance welding apparatus for performing resistance welding by sandwiching a workpiece between welding electrodes and conducting electricity.

 A displacement mechanism for displacing one welding electrode with respect to the other welding electrode,

 Pressing force detecting means for detecting a pressing force of the welding electrode with respect to the workpiece, a stop mechanism for stopping displacement of the one welding electrode,

 With

 The displacement mechanism,

 A motor controlled according to the pressing force detected by the pressing force detection means; a cam member driven by the motor;

 A follower provided on the welding electrode side, engaging with the cam member, and displacing the welding electrode in accordance with driving of the cam member;

 It is characterized by consisting of.

 According to the present invention, when the motor rotates, the cam member rotates, and this rotation is converted into linear motion by the follower, and one of the welding electrodes is displaced toward the workpiece. The welding electrode presses the workpiece, the applied pressure at this time is detected by the applied pressure detecting means, and when the applied pressure reaches a predetermined value, the displacement of the welding electrode is stopped by the stop mechanism, and the welding current is applied. To conduct welding.

 In this case, when the stop mechanism includes a brake for stopping the driving of the cam member and a clutch for intermittently connecting the cam member and the motor, the cam member can be stopped instantaneously, Is instantaneously stopped, which is preferable.

Further, the cam member has a cylindrical groove cam formed by orbiting a groove inclined with respect to the axial direction on the outer periphery of the cylindrical member. The distance between the disk member and the center of rotation of the disk member is A grooved cam formed by a changing groove orbiting, a plate cam having an outer peripheral surface that changes as the distance from the center of rotation changes, and a surface at one end of a cylindrical member is inclined with respect to its axial direction. Any of the end cams can be used.

 Further, the present invention provides a resistance welding apparatus for performing resistance welding by sandwiching an object to be welded between welding electrodes and supplying current thereto.

 Setting means for setting a pressing force of the welding electrode with respect to the workpiece; display means for displaying the set pressing force;

 A displacement mechanism for displacing one welding electrode with respect to the other welding electrode,

 Pressurizing force detecting means for detecting a pressing force of the welding electrode against the workpiece.

 In this case, the operator can set a desired pressing force based on the display on the display means, and the displacement mechanism can displace the welding electrode so as to obtain the set pressing force. .

 Moreover, by displaying the set pressing force and the detected pressing force on the display means, the operator can perform the work while checking the actual pressing force. BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a block diagram showing a resistance welding apparatus according to an embodiment of the present invention. FIG. 2 is a side view showing a displacement mechanism of the resistance welding apparatus of FIG.

 FIG. 3 is a longitudinal sectional view showing a clutch brake mechanism used in the displacement mechanism of FIG.

 FIG. 3 is a view showing a state in which the clutch is connected and the brake is released.

 FIG. 4 is a diagram showing a state in which the clutch is disengaged and the brake is applied.

 FIG. 5 is a perspective view showing a cylindrical groove cam used in the displacement mechanism of FIG.

FIG. 6 is a longitudinal sectional view showing the displacement mechanism of FIG. FIG. 7 is a diagram showing a state in which the workpiece is sandwiched between the upper welding electrode and the lower welding electrode.

 FIG. 8 is a diagram showing a state where the workpiece is welded.

 FIG. 9 is a flowchart illustrating a method of using the resistance welding apparatus of FIG. FIG. 10 is a flowchart illustrating a method of using the resistance welding apparatus of FIG. FIG. 11 is a flowchart illustrating another method of using the resistance welding apparatus in FIG. 1.

 FIG. 12 is an explanatory diagram of the processing according to the flowchart shown in FIG. FIG. 13 is a timing chart for the processing according to the flowchart shown in FIG.

 FIG. 14 is a partially enlarged side view showing a groove cam used in a resistance welding apparatus according to another embodiment of the present invention.

 FIG. 15 is a perspective view showing the groove cam of FIG.

 FIG. 16 is a partially enlarged side view showing a plate cam used in a resistance welding apparatus according to another embodiment of the present invention.

 FIG. 17 is a perspective view showing the plate cam of FIG.

 FIG. 18 is a partially enlarged side view showing an end cam used in a resistance welding apparatus according to still another embodiment of the present invention.

 FIG. 19 is a perspective view showing the end cam of FIG.

 FIG. 20 is a longitudinal sectional view showing a pressurizing mechanism used in a resistance welding apparatus according to still another embodiment of the present invention.

 FIG. 21 is a partially enlarged perspective view showing an upper welding electrode used in the pressurizing mechanism shown in FIG.

 FIG. 22 is a partially enlarged longitudinal sectional view showing a state where the work to be welded is welded by the pressurizing mechanism of FIG. BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the resistance welding apparatus according to the present invention will be described with reference to the accompanying drawings. This will be described in detail below with reference to FIG.

 In FIG. 1, reference numeral 10 indicates a resistance welding apparatus according to an embodiment of the present invention. This resistance welding apparatus 10 includes a displacement mechanism 16 for displacing a pressurizing mechanism 13 provided with an upper welding electrode 12 in a direction to approach or separate from a lower welding electrode 14, and a displacement mechanism 16. A controller 18 to be controlled and a welding power source 20 for applying a welding current to the upper welding electrode 12 and the lower welding electrode 14 under the control of the controller 18 are provided. Note that a foot switch 19 for starting the resistance welding apparatus 10 is connected to the controller 18.

 The controller 18 is provided with an LCD display 18a indicating the operation status and the like of the resistance welding device 10 and a plurality of setting switches 18b for setting and operating the resistance welding device 10 and the like. The setting switch 18b functions as setting means for setting the pressure applied to the workpiece by the pressurizing mechanism 13. In addition, the LCD display 18a functions as display means for displaying the set pressing force and displaying the pressing force detected during the operation of the resistance welding apparatus 10.

 The displacement mechanism 16 includes a base 22 as shown in FIG. A lower electrode holder 24 is fixed to the base 22, and a lower welding electrode 14 is fixed to the lower electrode holder 24. An electric wire 26 for supplying a welding current from the welding power source 20 to the lower welding electrode 14 is connected to the lower electrode holder 24.

A support 28 is erected on the base 22, and a motor 30 is provided above the support 28. The motor brake 30 is connected to the motor 30. As shown in FIGS. 3 and 4, the clutch-brake mechanism 32 has a housing 34, and a clutch portion 35 and a brake portion 37 are disposed inside the housing 34. The clutch portion 35 has a clutch plate 36 fixed to the rotating shaft of the motor 30, and a disk member 40 connected to the output shaft 38 faces the clutch plate 36. The disk member 40 is provided with spring members 42a and 42, and the spring members 42a and 42b are provided with ring-shaped contacts 44a and 44b made of a magnetic material. . Inside the housing 34, there are provided a clutch excitation coil 46 that allows the contacts 44a and 44b to approach and separate, and a brake excitation coil 48 that constitutes the brake section 37. The brake excitation coil 4 8 The brake plate 50 is fixed.

 A cylindrical member 56 constituting a cylindrical groove cam 54 is fixed to the output shaft 38, and a groove 58 inclined with respect to the axis thereof is provided on the outer periphery of the cylindrical member 56 as shown in FIG. It is formed by orbiting. Rollers 62 forming a follower 60 are rotatably inserted into the grooves 58, and the rollers 62 are rotatably provided on a displacement plate 64 via support members 63 (see FIG. 2). . A guide block 66 is fixed to the displacement plate 64, and a hole 68 extending in the vertical direction is formed in the guide block 66. Bushings 70a and 70b are provided on the wall forming the hole 68. A guide rod 72 provided in the bush 70a, 70b so as to extend in the vertical direction through the support column 28 via the support members 71a, 71b is inserted into the bush 70a, 70b. Numeral 6 4 is configured to be vertically displaceable along the guide rod 72.

 A pressure mechanism 13 is fixed to the displacement plate 64. The pressurizing mechanism 13 includes a body 76 as shown in FIG. The body 76 has a lower body 78 and an upper body 80, and through holes 82, 84 are formed from the lower body 78 to the upper body 80. Linear pole bearings 86, 88 are provided in the through holes 82, 84, and the pressure transmitting shaft 90 is slidably inserted into the linear ball bearings 86, 88. The upper welding electrode 12 is attached to a lower portion of the pressure transmission shaft 90 via an upper electrode holder 92. An electric wire 94 for supplying a welding current from the welding power source 20 to the upper welding electrode 12 is connected to the upper electrode holder 92 (see FIG. 2).

 A first spring receiver 96 is fixed to an upper portion of the pressure transmitting shaft 90 via a port, and one end of a coil spring 100 is seated on the first spring receiver 96. The coil spring 100 is housed in a concave portion 102 formed in the upper body 80, and the distal end portion of the cylindrical member 104 fits into the concave portion 102. The cylindrical member 104 is fixed to the upper body 80 by screwing a nut 106 into a screw engraved on the outer periphery thereof.

A second spring receiver 108 is slidably inserted into the cylindrical member 104, and the other end of the coil spring 100 is seated in the second spring receiver 108. A recess 110 is formed in the upper center of the second spring receiver 108, and this recess is formed. A first pole member 112 is seated on 110. A spacer 114 is slidably provided inside the cylindrical member 104 at a predetermined distance from the second spring receiver 108. A concave portion 116 is formed in the spacer 111 so as to face the concave portion 110, and an upper portion of the first ball member 112 is seated in the concave portion 116. A concave portion 118 is formed in the upper center of the spacer 114, and a detector 122 of a strain gauge (load cell) 120, which is a pressing force detecting means, is seated in the concave portion 118. A wire 124 connected to the controller 18 is led out from the strain gauge 120 (see FIG. 1), and the pressure applied to the upper welding electrode 12 via the wire 124 is extracted as an electric signal. Note that as the strain gauge 120, a material utilizing resistance change of a metal or a semiconductor can be used.

 A striking plate 128 is provided above the strain gauge 120. A curved concave portion 130 is formed at an upper portion of the plate 1 28, and a second ball member is formed between the curved concave portion 13 4 formed at the tip of the pressing force adjusting knob 13 2. Hold 1 3 6. The pressing force adjusting knob 1332 firmly holds the case 140 screwed to the cylindrical member 104 by the nut 1380.

 The resistance welding apparatus 10 according to the present embodiment is basically configured as described above. Next, the operation and the effects of the apparatus will be described.

First, prior to the welding work, the desired pressurizing force set values P i and P ₂ as the reference for starting welding are set using the setting switch 18 b of the controller 18. In this case, the inputted pressure set value P _t and P ₂ by the operator, to be displayed on the LCD display I 1 8 a, it can be confirmed that entered the desired set value. Therefore, as shown in FIG. 2, the objects to be welded 146 and 148 are placed between the lower welding electrode 14 and the upper welding electrode 12 so as to overlap (step S 1 in FIG. 9). Also, as shown in FIG. 4, a current is applied to the brake excitation coil 48 to draw the contact 44 b, and the contact 44 b is brought into contact with the brake plate 50 and the contact a is separated from the clutch plate 36. Therefore, the brake is applied to the output shaft 38, and the cylindrical groove cam 54 does not rotate.

After the preparation steps described above, the operator operates the foot switch 19 and controls When the motor 30 is driven under the control of the roller 18, the clutch plate 36 rotates. At this point, the contact 44 a separates from the clutch plate 36, and the contact 4 4 Since b is in contact with the brake plate 50, the cylindrical groove cam 54 is stopped. When the current supplied to the brake excitation coil 48 is stopped and the current is supplied to the clutch excitation coil 46, as shown in FIG. The contact 44 a contacts the clutch plate 36, and the rotational force of the motor 30 is transmitted to the cylindrical groove cam 54. Then, the rotary motion is converted into a linear motion by the rollers 62 engaging with the groove portions 58 of the cylindrical groove cams 54, and the pressurizing mechanism 13 is lowered (step S2). For this reason, the upper welding electrode 12 comes into contact with the upper surface of the work piece 148, and the work pieces 146, 148 are sandwiched between the upper welding electrode 12 and the lower welding electrode 14. (See Figure 7).

 The upper welding electrode 12 presses the workpiece 1 4 8 under the further lowering action of the pressurizing mechanism 13, and the pressing force transmission shaft 90 piles on the elastic force of the coil spring 100 to relatively move. Rise (see Figure 6). For this reason, the coil spring 100 contracts, and the pressing force P of the upper welding electrode 12 on the object to be welded 148 gradually increases. The magnitude of the pressure P is measured by a strain gauge 120.

 At this time, the first pole member 1 1 2 and the second ball member 1 36 are in the case where the pressing mechanism 13 changes its angle with respect to the workpieces 1 4 6 and 1 4 8. Also faithfully transmits the fluctuation of the pressure P to the strain gauge 120. Therefore, even when the objects to be welded 146 and 148 are inclined, the pressing force P is reliably transmitted to the strain gauge 120.

The controller 18 compares this pressure P with a predetermined pressure set value (step S3). If the pressure P is smaller than the pressure set value P i, the controller 18 returns to step S2 and presses the pressure mechanism. Lower 1 3 further. Then, when the pressing force P matches the pressing force set value P i, the current supplied to the clutch exciting coil 46 is stopped, and the current is supplied to the brake exciting coil 48. The contact 44 a separates from the clutch plate 36, and the contact 44 b contacts the brake plate 50 to apply the brake, and the rotation of the cylindrical groove cam 54 stops. For this reason, the lowering of the pressure mechanism 13 stops. Then (step S 4), the object to be welded 148 is kept pressed against the upper welding electrode 12 by the pressing force set value P i. As described above, the workpieces 1 4 6 and 1 4 8 are sandwiched between the upper welding electrode 12 and the lower welding electrode 14 at the pressure setting value P i, so that the upper welding electrode 12 and the workpiece 1 4, the contact resistance between the workpiece 1 46 and the workpiece 1 48 and between the workpiece 1 46 and the lower welding electrode 14 are maintained at predetermined values. Also, since the rotation of the cylindrical groove cam 54 is stopped by disengaging the clutch portion 35 of the clutch brake mechanism 32 and activating the brake portion 37, the inertia of the motor 30 is applied to the pressurizing mechanism 13. The pressing mechanism 13 can be stopped instantaneously without being transmitted, and the error of the pressing force P can be reduced.

 It is to be noted that there is a concern that the objects to be welded 146 and 148 may generate vibration or the like due to an impact when sandwiched between the upper welding electrode 12 and the lower welding electrode 14. Therefore, it is preferable to maintain the state in which the pressurizing mechanism 13 is stopped for a predetermined squeeze time, because vibrations and the like generated in the objects to be welded 144 and 148 are converged.

 Next, the controller 18 performs welding on the objects to be welded 146 and 148. This welding method will be described in detail with reference to the flowchart of FIG. 10. First, the controller 18 outputs a temporary welding command signal to the welding power source 20. For this reason, the welding power source 20 supplies a temporary welding current between the upper welding electrode 12 and the lower welding electrode 14 in accordance with the temporary welding command signal, and temporarily supplies the temporary welding current to the workpieces 144, 148. The welding is performed (step S10). In this state, the welding is insufficient and the strength is insufficient. The contact resistance between the object to be welded 1 46 and the object to be welded 1 48 is sufficiently small. In addition, even if the contact resistance varies when the workpieces 14 6 and 14 48 are sandwiched between the upper welding electrode 12 and the lower welding electrode 14, even if the contact resistance varies, the contact resistance is substantially constant by the temporary welding. Become.

At this time, the thickness of the workpieces 1 4 6 and 1 4 8 is slightly reduced by temporary welding, and the upper welding electrode 12 is displaced and the pressure P detected by the strain gauge 1 20 is set to the pressing force. Less than the value. Therefore, the controller 18 controls the clutch brake mechanism 32 while measuring the pressing force P with the strain gauge 120 to connect the clutch part 35 and release the brake part 37, thereby controlling the motor 30 Times The rolling force is transmitted to the cylindrical groove cam 54, and the pressing mechanism 13 is lowered (step S11). The controller 1 8 compares the predetermined and pressure set value P ₂ set for pressurizing force P and the welding (step S 1 2), the clutch when the pressure P is coincident with the pressure set value P ₂ The brake mechanism 32 is controlled to release the connection of the clutch part 35, and the brake part 37 is operated to stop the rotation of the cylindrical groove cam 54 and stop the lowering of the caropressure mechanism 13 ( Step S13).

 Next, the controller 18 outputs a main welding command signal to the welding power source 20, and the welding power source 20 supplies a main welding current between the upper welding electrode 12 and the lower welding electrode 14 to perform welding. The main welding is performed on the objects 146 and 148 (step S14). At this time, since the contact resistance between the object to be welded 1 46 and the object to be welded 1 48 is sufficiently small due to the temporary welding and there is no variation, a predetermined size as shown in FIG. A nugget 150 is formed and good welding is performed.

 At this time, the nuggets 150 formed on the objects to be welded 146 and 148 are in a molten state. Therefore, after a predetermined hold time has elapsed, the nugget 150 is solidified.

Then, when the controller 18 rotates the motor 30 in the reverse direction and controls the clutch / brake mechanism 32 to rotate the cylindrical groove cam 54, the pressurizing mechanism 13 rises, and welding is stopped. The completed workpieces 1 4 6 and 1 4 8 are taken out (Step S 15) According to the present embodiment, the pressure P of the upper welding electrode 12 is measured by the strain gauge 120, and this pressure because P is welded at the time when a pressure setpoint P _2, the upper welding electrode 1 2, there is no need to manage the length of the lower welding electrode 1 4, welding work industry is facilitated, also maintenance of the process Less.

 Further, unlike the prior art, no pole screw or compressed air supply source is required, and the cost of the resistance welding apparatus 10 can be reduced.

Further, when the displacement of the pressurizing mechanism 13 is stopped, the transmission of the rotational force of the motor 30 is disconnected by the clutch 35 of the clutch brake mechanism 32, and the cylindrical groove cam is transmitted by the brake 37. Because the brake is applied to the rotation of 5 4, due to the inertia of 30 The pressurizing mechanism 13 is prevented from being displaced more than necessary, and the pressing force P of the upper welding electrode 12 on the workpiece 148 can be accurately controlled.

 In the present embodiment, welding is performed in two steps, temporary welding and main welding, but welding may be performed only once. In this case, the working time can be reduced.

 Further, the welding may be performed without stopping the lowering of the pressurizing mechanism 13 in step S13. This resistance welding method will be described with reference to FIGS.

First, prior to the welding operation, a desired pressure setting value Pi as a reference for starting welding is set by using the setting switch 18b of the controller 18. In this case, the pressure setting value Pi input by the operator is displayed on the LCD display 18a, so that it is possible to confirm that the desired setting value has been input. The constant value is exemplified as 2.00 kg gZ f.) Further, whether or not in the present embodiment, are within the predetermined range pressure P applied pressure P after the predetermined time t has elapsed after reaching the pressure set point Pi is referenced to the pressure set value P ₂ to verify, using L CD display 18 a and set switch 1 8 b, setting the predetermined time t Contact and pressure setpoint P _2.

Therefore, similarly to the above-described method, the objects to be welded 146 and 148 are placed in an overlapping manner between the lower welding electrode 14 and the upper welding electrode 12 (step S 21), and the operator operates the foot switch 19. Then, the START signal output from the foot switch 19 is supplied to the controller 18. The controller 18 drives the motor 30 by this START signal. When the motor 30 is driven, the pressurizing mechanism 13 is lowered, and the workpieces 146 and 148 are sandwiched between the upper welding electrode 12 and the lower welding electrode 14 (Step S22, see FIG. 7). Then, PSG signal according to the pressure P detected by the strain gauges 120 is supplied to the controller 18, the pressure P of the stored pressure setpoint P ₁ Toko are compared (Step S 23). When the applied pressure P matches the set pressure value (see the dotted line 1 in FIG. 13), the controller 18 outputs a WELD signal to the welding power source 20. When the welding power source 20 receives the WELD signal, the welding current I is transmitted to the upper welding electrode 12 and the lower welding electrode 14. And welding is performed while lowering the pressurizing mechanism 13 (step S24). Here, the WE LD signal is output for a predetermined time t set by the operator. At a point in time after the predetermined time t has elapsed (see the dotted line 2 in FIG. 13), the controller 18 detects the pressure P on the basis of a PSG signal from the strain gauge 1 2 0, determine whether the pressure P is in the allowable within range relative to the pressure set value P ₂ set by the operator If it is within the range, it outputs an OK signal, and if it is not within the range, it outputs an NG signal. The pressing force P at this time is displayed on the LCD display 18a of the controller 18. Therefore, using the OK / NG signal or the displayed pressing force P, for example, it is possible to perform processing such as a warning relating to the quality of the welding state or to determine that the resistance welding apparatus 10 is operating normally. It can be confirmed at the time.

 When the welding is completed, the clutch brake mechanism 32 is controlled to stop the rotation of the cylindrical groove cam 54, and the descent of the pressurizing mechanism 13 is stopped (step S25). After the predetermined hold time has elapsed and the nugget 150 has solidified, the controller 18 rotates the motor 30 in the reverse direction and controls the clutch brake mechanism 32 to control the cylindrical groove force. When 54 is rotated, the pressurizing mechanism 13 is lifted, and the welded objects 144 and 148 which have been welded are removed (step S26).

 As described above, since welding is performed while applying the pressing force P, the welding force P does not become insufficient during welding, and good welding quality can be obtained.

 Next, a resistance welding apparatus 200 according to another embodiment of the present invention using a groove cam instead of the above-described cylindrical groove cam 54 as a cam member for displacing the pressing mechanism 13 will be described with reference to FIG. This will be described with reference to FIGS. Note that the same components as those of the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

A motor 202 and a clutch brake mechanism 204 are provided above a support column 28 of the resistance welding apparatus 200, and an output shaft 206 of the clutch brake mechanism 204 extends in a horizontal direction. It is located and located. The output shaft 206 is provided with a disk member 2 12 constituting the groove cam 210, and the disk member 2 12 has a groove 2 14 orbiting so that the distance from the center of rotation changes. It is formed. The grooves 2 14 are provided on the displacement plate 64 The rollers 62 of the follower 60 are engaged.

 When the motor 202 rotates and the clutch / brake mechanism 204 is controlled to transmit the torque of the motor 202 to the output shaft 206, the disk member 212 rotates. For this reason, this rotational motion is converted into linear motion by the rollers 62, and the displacement plate 64 is displaced in the vertical direction. Accordingly, the pressurizing mechanism 13 fixed to the displacement plate 64 is displaced, and the upper welding electrode 12 is pressed against the workpiece 1 488.

 In the resistance welding apparatus 300 according to another embodiment, a plate cam is used as the cam member. As shown in FIGS. 16 and 17, on the upper part of the column 28 of the resistance welding apparatus 300, a motor 302 and a clutch brake mechanism 304 are provided, and a clutch brake mechanism 304 is provided. The output shaft 303 is disposed to extend in the horizontal direction. The output shaft 303 is provided with a plate cam 312, and the plate cam 312 is formed so that the distance from the center of rotation to the outer peripheral surface 314 changes as it goes around. A roller 62 provided on the displacement plate 64 and constituting a follower 60 comes into contact with the outer peripheral surface 3 14. A support member 316 bent in a crank shape is fixed to the upper part of the motor and brake clutch mechanism 304. One end of a coil spring 3 18 is provided at an end of the support member 3 16, and the other end of the coil spring 3 18 is connected to a support member 6 3 connecting the displacement plate 6 4 and the roller 6 2. Provided. Therefore, the displacement plate 64 is always urged upward.

 When the motor 302 rotates and the clutch brake mechanism 304 is controlled to transmit the torque of the motor 302 to the output shaft 303, the plate cam 310 rotates. The roller 6 2 is urged by the coil spring 3 18 and abuts on the outer peripheral surface 3 14 of the plate cam 3 12 to convert the rotary motion of the plate cam 3 12 into a linear motion. Therefore, the displacement plate 64 is displaced in the vertical direction. Therefore, the pressurizing mechanism 13 fixed to the displacement plate 64 is displaced, and the upper welding electrode 12 presses the workpiece 1 488.

In the resistance welding apparatus 400 according to still another embodiment, an end face force is used as a cam member. As shown in FIGS. 18 and 19, a plate-like member 402 is erected above the column 28 of the resistance welding apparatus 400, and the plate-like member 402 is 0 4 and a clutch brake mechanism 4 06 are provided. The output shaft 408 is provided so as to protrude downward. The output shaft 408 is provided with an end cam 412 formed in a substantially cylindrical shape, and a lower end surface 414 of the end cam 412 is inclined with respect to the axis of the end cam 412. A roller 62 provided on the displacement plate 64 and constituting the follower 60 abuts on the lower end surface 414.

 A support member 416 bent in a crank shape is fixed to the upper part of the plate member 402. One end of a coil spring 418 is provided at an end of the support member 416, and the other end of the coil spring 418 is provided on a support member 63 connecting the displacement plate 64 and the place 62. Therefore, the displacement plate 64 is always urged upward.

 When the motor 404 rotates and the clutch brake mechanism 406 is controlled and the torque of the motor 404 is transmitted to the output shaft 408, the end cam 412 rotates. The roller 62 is urged by the coil spring 418 and abuts against the lower end surface 414 of the end cam 412 to convert the rotational movement of the end cam 412 into a linear movement. Therefore, the displacement plate 64 is displaced upward and downward. Accordingly, the pressurizing mechanism 13 fixed to the displacement plate 64 is displaced, and the upper welding electrode 12 is pressed against the workpiece 148.

 In the above-described embodiment, one upper welding electrode 12 is provided in the pressurizing mechanism 13, but a plurality of electrodes may be provided as described below with reference to FIGS.

 The pressing mechanism 500 includes two upper welding electrodes 504a and 504b. The housing 506 of the pressing mechanism 500 is covered by a shield 508. Holes 510a and 510b are defined in the lower portion of the housing 506, and bushings 512a to 512d are provided in the holes 510a and 510b. The bushings 512a to 512d are penetrated by the pressure transmission shafts 514a and 514b, and the plate transmission upper shaft 514a and 514b have a plate-like upper electrode holder 5 at the lower end. 16a and 516b are fixed. In the vicinity of one corner of the upper electrode holders 516a and 516b, as shown in FIG. 21, rod-shaped upper welding electrodes 504a and 504b are erected in the vertical direction. The distance between a and 504b is smaller than the distance between the pressure transmission shafts 514a and 514b.

A plate-shaped member 518 is bridged above the pressure transmission shafts 514a and 514b. Rollers 526a and 526b are rotatably supported on the upper part of the plate-shaped member 518. The housing 506 has a hole 528 defined therein. 8 is provided with bushes 5300a and 53Ob. A shaft 532 is slidably inserted through the bushings 530a and 530b, and a swing member 534 is provided at the lower end of the shaft 532 so as to be swingable. Rollers 526a and 526b can freely contact the swinging member 534, so that the upper welding electrodes 504a and 504b are inclined so that the workpiece 1 4 6, Even when it comes into contact with 148, the pressing force of the coil spring 100 provided on the upper part of the shaft 532 is still exerted by the swinging member 534 and the rollers 526a and 526b. The force is divided into substantially the same force and transmitted to the upper welding electrodes 504a and 504b. Therefore, the upper welding electrode 504a and the upper welding electrode 504b are pressed against the workpieces 146, 148 with substantially the same force, resulting in substantially the same welding conditions (see FIG. 22). ).

 As shown in FIG. 22, the pressurizing mechanism 500 is connected to one upper welding electrode 504 a to one welding current terminal 20 a of the welding power source 20 and the other upper welding electrode. The other welding current terminal 20b is connected to 504b. Protrusions 538a and 538b corresponding to the upper welding electrodes 504a and 504b are formed on the lower welding electrode 536 formed in a plate shape of the displacement mechanism 16.

 When a welding current is passed from one welding current terminal 20a of the welding power source 20 to the other welding current terminal 20b, as shown by the arrow in FIG. 22, the workpieces 1 4 6 and 1 4 A welding current flows through 8, and welding is performed.

 With this configuration, the two upper welding electrodes 504a and 504b can simultaneously perform welding at two locations in one welding operation, thereby improving work efficiency.

In this case, one upper welding electrode 504a was connected to one welding current terminal 20a, and the other upper welding electrode 504b was connected to the other welding current terminal 20b. The welding current terminal 20a may be connected to both upper welding electrodes 504a and 504b, and the other welding current terminal 20b may be connected to the lower welding electrode 536. Industrial applicability According to the resistance welding apparatus of the present invention, the following industrial applicability is obtained.

 The welding electrode is pressed while measuring the pressing force of the welding electrode against the workpiece by the pressure detecting means, and when the pressing force reaches a predetermined value, the displacement of the welding electrode is stopped and welding is performed. The length control can be simplified, the welding work is simplified, and the number of maintenance steps is reduced. Therefore, work efficiency is improved. In addition, since the rotational force of the motor is converted to linear motion by the cam member and the follower to displace the displacement mechanism, expensive motor and pole screws are not required, and the cost of the resistance welding device is reduced. be able to.

 Further, when the displacement of the welding electrode is stopped, the transmission of the rotational force of the motor is cut off by the clutch, and the driving of the cam member is stopped by the brake. Displacement is prevented, displacement of the welding electrode can be stopped instantaneously, and the pressing force of the welding electrode on the workpiece can be accurately controlled.

 Further, the operator can set a desired pressing force based on the display on the display means, and the displacement mechanism can displace the welding electrode so as to obtain the set pressing force. it can. In addition, by displaying the set pressing force and the detected pressing force on the display means, the operator can perform the work while checking the actual pressing force.

Claims

The scope of the claims 1. In a resistance welding device that performs resistance welding by sandwiching an object to be welded between welding electrodes and conducting electricity,  A displacement mechanism for displacing one welding electrode with respect to the other welding electrode,  Pressing force detecting means for detecting a pressing force of the welding electrode with respect to the workpiece, a stop mechanism for stopping displacement of the one welding electrode,  With  The displacement mechanism,  A motor controlled in accordance with the pressing force detected by the pressing force detecting means; a cam member driven by the pressing force;  A follower provided on the welding electrode side, engaging with the cam member, and displacing the welding electrode in accordance with driving of the cam member;  A resistance welding apparatus characterized by comprising: 2. The resistance welding apparatus according to claim 1,  The resistance welding device, wherein the stopping mechanism includes a brake for stopping driving of the cam member, and a clutch for intermittently connecting the cam member and the motor. 3. The resistance welding apparatus according to claim 2,  The resistance welding apparatus, wherein the brake and the clutch include a mechanism for electromagnetically connecting and disconnecting the cam member and the motor. 4. The resistance welding apparatus according to claim 1,  The resistance welding apparatus according to claim 1, wherein the cam member is a cylindrical groove cam formed by forming a groove, which is inclined with respect to an axial direction, around an outer periphery of a cylindrical member. 5. The resistance welding apparatus according to claim 1, The resistance welding apparatus according to claim 1, wherein the cam member is a groove cam formed by orbiting a disk member having a groove portion whose distance from the rotation center of the disk member changes. 6. The resistance welding apparatus according to claim 1,  The resistance welding apparatus, wherein the cam member is a plate cam having an outer peripheral surface that changes as the distance from the center of rotation goes around. 7. The resistance welding apparatus according to claim 1,  The resistance welding device, wherein the cam member has an end surface force whose one end surface of the columnar member is inclined with respect to the axial direction. 8. The resistance welding apparatus according to claim 1,  Wherein the pressure detecting means comprises a strain gauge. 9. In a resistance welding device that performs resistance welding by sandwiching a workpiece between welding electrodes and conducting electricity,  Setting means for setting a pressing force of the welding electrode with respect to the workpiece; display means for displaying the set pressing force;  A displacement mechanism for displacing one welding electrode with respect to the other welding electrode,  And a pressing force detecting means for detecting a pressing force of the welding electrode on the workpiece. 10. The apparatus according to claim 9,  The resistance welding apparatus, wherein the display means displays the set pressing force and the detected pressing force. 11. The resistance welding apparatus according to claim 9, The pressure detecting means comprises a strain gauge.