JP2002172471A - Adjusting mechanism for height of lower electrode in resistance welding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust the position of the height of a lower electrode rapidly and correctly by automatically moving and adjusting to the welding position in exchanging the lower electrode, in a resistance welding machine provided with a rotatable and disclike upper electrode and a lower electrode. SOLUTION: In exchanging the lower electrode 3, a driving motor 14 of a lifting driving device 13 is driven to lower the center of the lower electrode 3 to the reference position, the peripheral position of the new lower electrode 3 after the exchange is measured by the measuring device 26A, on the basis of the measured value and the distance from the center of the lower electrode 3 in the reference position to the height of the position of the upper edge of the peripheral face of the lower electrode 3 in the prescribed welding position, the raised amount of the lower electrode 3 is calculated, and on the basis of the calculated value, the driving motor 14 of the lifting driving motor 13 is reversely driven to lift the new lower electrode 3 to the specific welding position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance welding machine having a rotatable disk-shaped upper electrode and a lower electrode.
The present invention relates to a mechanism for adjusting the height of a lower electrode capable of quickly and accurately adjusting the height position of the lower electrode.

[0002]

2. Description of the Related Art A rotatable disk-shaped upper electrode and a lower electrode are provided.
2. Description of the Related Art A resistance welding machine that continuously welds a workpiece by rotating both electrodes is known.

In such a resistance welding machine, at the time of welding work, the lower electrode is held at a predetermined welding position, while the upper electrode provided so as to be able to move up and down is pressed down from above by a pressing force of an air cylinder or the like. As a result, a predetermined pressure is applied between the upper and lower peripheral surfaces of the two disc-shaped electrodes, and a large current is applied between the two electrodes in this state, so that the two pieces are in contact with each other. An exothermic melting action is caused by the resistance, and the pinching portion moved by the rotation of both electrodes can be sequentially and continuously welded through the exothermic melting action.

[0004]

By the way, in such a welding method, the peripheral surfaces of both disc-shaped electrodes are gradually worn by the welding operation. Here, the upper electrode is provided so as to be able to move up and down as described above, and is pressed down from an upper standby position by an air cylinder or the like during welding work. It can be pressed against the work to be welded,
The replacement of the upper electrode can be easily performed at the upper standby position. On the other hand, although the lower electrode is mounted on a vertically movable slide table, usually, the slide table is tightened with a plurality of bolts at a height position for holding the lower electrode at a predetermined welding position. The lower electrode is fixed so as not to be able to move up and down, and the lower electrode is also moved up and down by a manual jack arranged at the lower part of the slide table.

[0005] For this reason, the wear of the peripheral surface of the lower electrode causes
When it is necessary to raise the lower electrode by the amount of the wear, or when the lower electrode is temporarily worn down and replaced once without any hindrance to work, and then raised again to the predetermined welding position. After loosening the plurality of bolts tightening the slide holder to enable the slide table to move up and down, operate the manual jack to raise and lower the lower electrode, and then remove the slide holder bolt again at the specified height. The slide table must be fixed tightly. For this reason, it takes time and effort to perform a series of tasks,
There is a problem that it is very difficult to accurately adjust the height position of the upper edge of the peripheral surface of the lower electrode to a predetermined height at the welding position by manual adjustment by visual observation. In particular, when the upper edge of the peripheral surface of the lower electrode is hidden by the object to be welded in a state where the object to be welded is set, visual alignment has been made more difficult.

[0006] The present invention solves such a conventional problem,
It is an object of the present invention to provide a mechanism for adjusting the height of a lower electrode in a resistance welding machine, which can quickly and accurately adjust the movement of a lower electrode to a welding position.

[0007]

SUMMARY OF THE INVENTION The present invention comprises a rotatable disk-shaped upper electrode and a lower electrode, and applies a current by pressing a work to be welded between the two electrodes, and rotating the two electrodes to rotate the work. In a resistance welding machine for continuously welding objects, a lower electrode is mounted, a slide table provided so as to be able to move up and down, a drive motor capable of reversible rotation, and a transmission for converting the rotational motion of the drive motor into linear motion. Means for moving the lower end electrode up and down by connecting one end of the transmission means on the linear motion side to a slide table, and measuring the position of the lower electrode by contacting the lower electrode from the side. When replacing the measuring device and the lower electrode, the drive motor of the lifting drive device is driven to lower the center of the lower electrode to the reference position, and the peripheral surface position of the new lower electrode after replacement is measured by the measuring device. Measured values and the The lift amount of the lower electrode is calculated based on the distance from the center of the lower electrode at the position to the height position of the upper edge of the lower electrode at the predetermined welding position, and the elevation drive is performed based on the calculated value. A height control mechanism for the lower electrode in the resistance welding machine, comprising: a central control device having a control content for raising the new lower electrode to a predetermined welding position by reversely driving the drive motor of the device. It is.

Here, the measuring device can be set to output the radius of the lower electrode as a measured value by measuring the peripheral surface position of the lower electrode, and the output signal is sent to the central controller. Is entered. In addition, the reference position can be set at a height position at which the replacement operation of the lower electrode can be easily performed, and the height of the upper edge of the peripheral surface of the lower electrode at the welding position from the center of the lower electrode at the reference position. The distance to the position is predetermined.

In such a configuration, when replacing the lower electrode, the central control device drives the drive motor of the lifting drive device to control the number of rotations thereof, and lowers the slide table on which the lower electrode is mounted. Thereby, the center of the lower electrode is lowered to the reference position. Then, the replacement work of the lower electrode can be performed at the reference position. Thereafter, the measuring device is operated under the control of the central controller, the peripheral position of the new lower electrode is measured, and the radius of the lower electrode is sent to the central controller as a measured value. The central controller lowers the lower electrode by subtracting the input measured value of the lower electrode from the distance from the center of the lower electrode at the reference position to the height of the upper edge of the lower electrode at the welding position. The new lower electrode is raised to a predetermined welding position by calculating the distance to be driven and reversely driving the drive motor of the lifting drive device to control the number of rotations. Also, the new lower electrode is
The ascending position is held via the slide table by the stop control of the drive motor. Thereby, the movement adjustment to the welding position when replacing the lower electrode is automated, and the height position of the lower electrode can be quickly and accurately adjusted.

[0010] In the above-mentioned structure, the wear amount of the lower electrode is measured by the measuring device, and based on the wear amount, the drive motor of the elevation drive device is driven to raise the lower electrode to a predetermined welding position. The control content may be provided in the central control device. This makes it possible to adjust the height of the lower electrode according to the amount of wear not only during replacement but also during welding work.

Further, the present invention comprises a rotatable disk-shaped upper electrode and a lower electrode, and applies a current by sandwiching the work to be welded between both electrodes, and continuously rotates the work by rotating both electrodes. A resistance welding machine for performing a suitable welding, comprising a slide table provided with a lower electrode mounted thereon and capable of moving up and down, a drive motor capable of reversible rotation, and a transmission means for converting the rotational motion of the drive motor into a linear motion. An elevation drive device that connects one end of the transmission means on the linear motion side to a slide table to raise and lower the lower electrode, and a measuring device that contacts the upper edge of the lower electrode from above to measure its height position. When replacing the lower electrode, drive the drive motor of the lifting drive to lower the center of the lower electrode to the reference position, and measure the height position of the upper edge of the new lower electrode after replacement with a measuring device. , Based on that measurement Calculate the distance to the height position of the upper edge of the lower electrode at the predetermined welding position, and reversely drive the drive motor of the lifting / lowering drive device based on the calculated value to weld the new lower electrode to the predetermined welding position. A height control mechanism for the lower electrode in the resistance welding machine, comprising a central control device having a control content for raising the position to a position.

In this configuration, when the lower electrode is replaced, the drive motor of the elevation drive device is driven by the control of the central control device, and the center of the lower electrode is set to the reference position through the lowering of the slide table. And the lower electrode can be replaced at the reference position. Thereafter, the measuring device is operated under the control of the central control device, the height position of the upper peripheral edge of the new lower electrode is measured, and the measured value is sent to the central control device. The central controller subtracts the measured value of the upper edge of the lower electrode at the input reference position from the set value of the height position of the upper edge of the lower electrode at the predetermined welding position to obtain the lower electrode. The new lower electrode is raised to a predetermined welding position by controlling the number of rotations by reversely driving the drive motor of the lifting drive device, and the stop motor is controlled through the slide table by stop control of the drive motor. Hold the ascent position. Thereby, the movement adjustment to the welding position when replacing the lower electrode is automated, and the height position of the lower electrode can be quickly and accurately adjusted.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a lower electrode height adjusting mechanism in a resistance welding machine according to the present invention will be described below with reference to FIGS.

As shown in FIG. 1, the resistance welding machine 1 includes a disk-shaped upper electrode 2 and a lower electrode 3 which are disposed vertically and opposed to each other. The upper electrode 2 is pushed down from the upper standby position via pressure, and a current is applied in a state where the workpiece w is sandwiched between the upper electrode 2 and the lower electrode 3 held at a predetermined welding position. , The workpiece w can be continuously welded.

The lower electrode 3 is mounted on a vertically movable slide table 4. That is, the slide table 4
As shown in FIG. 2 and FIG. 3, a vertical substrate 6 provided with a pair of upper and lower sliders 5 on the right and left sides of the rear surface, and a horizontal substrate 7 protruding from the front upper portion of the vertical substrate 6, A pair of left and right reinforcing plates 8 and 8 fixed to the front surface of the vertical substrate 6 and supporting the horizontal substrate 7 at the upper edge thereof, and sliders 5 and 5 of the vertical substrate 6 are mounted on a base frame. 9 are slidably engaged with up-and-down guide rails 10, 10 arranged in a pair on the left and right sides on the front surface. A bearing device 11 having an energizing function is fixed on the horizontal substrate 7, and the lower electrode 3 is detachably mounted on a rotating mounting portion 12 protruding forward from the bearing device 11. Then, along the guide rails 10, 10, the slide table 4
Is driven up and down so that the lower electrode 3 mounted on the slide table 4 can be moved up and down.

Below the slide table 4, a lifting drive 13 for raising and lowering the lower electrode 3 is provided. The lifting / lowering drive device 13 includes a drive motor 14 capable of reversible rotation, and a transmission means 15 for converting the rotational motion of the drive motor 14 into a linear motion.
Is connected to the slide table 4.

A servomotor whose number of rotations can be controlled is preferably used as the drive motor 14. The drive motor 14 is provided on a side of a support 16 protruding from the front surface of the base frame 9. Is fixed laterally via a bracket 17. As the transmission means 15, a ball screw type power jack as shown in FIG. 4 can be suitably used. The power jack includes a worm 20 supported by an input shaft 19, a worm wheel 21 meshed with the worm 20, and a worm wheel 21 in a main body case 18 fixed to the upper surface of the support base 16. A plurality of ball nuts 22 integrally fixed are accommodated in the upper part of the body, and an elevating rod 23 composed of a ball screw shaft screwed to the ball nut 22 is projected upward from the main body case 18. The upper end is the horizontal substrate 7 of the slide table 4
Fixed to. The input shaft 19 is connected to the main body case 1.
8 protrudes laterally from the rotating shaft 1 of the drive motor 14.
4a via a coupling 24. Further, a cover tubular body 25 that covers a lower portion of the elevating rod 23 protruding downward by screwing is disposed below the main body case 18.

In the lifting drive device 13, the drive motor 14 drives the worm 20 through the input shaft 19.
Is rotated, the worm wheel 21 meshing with the worm 20 rotates horizontally, and the plurality of ball nuts 22 fixed to the worm wheel 21 simultaneously rotate horizontally. As a result, a vertical screwing action is generated on the elevating rod 23 composed of the ball screw shaft screwed with the ball nut 22, and the elevating rod 23 moves forward and backward in accordance with the rotation direction of the ball nut 22. Since the upper end of the lift rod 23 is fixed to the horizontal substrate 7 of the slide table 4, the slide table 4 is driven up and down by the forward and backward movement of the lift rod 23.

On the side of the lower electrode 3, there is provided a measuring device 26A which is in contact with the peripheral surface of the lower electrode 3 from the side to measure the peripheral surface position. The measuring device 26A
Is attached to a support arm 27 extending from the horizontal substrate 7 of the slide table 4 and moves up and down together with the lower electrode 3. Thereby, the position of the peripheral surface of the lower electrode 3 can always be measured irrespective of the height position of the lower electrode 3 due to the elevation drive of the slide table 4. The measuring device 26A has a function of driving a rod 28 having a roller-shaped contact end 28a at the tip thereof, and a function of detecting a movement stroke of the rod 28 and outputting a detection signal. The measuring device 26A is configured to detect a movement stroke of a piston rod of an air cylinder using a magnetoresistive element and output the pulse as a pulse signal.
C) "is suitably used. Also, a linear encoder detects the movement stroke of the piston rod of the air cylinder, or a rack driven by a motor driven pinion, and the amount of movement is detected by a rotary encoder attached to the motor rotation shaft. It is also possible to apply such a method as described above. Then, the measuring device 26A sets the center position of the lower electrode 3 at the origin and causes the front edge of the contact end 28a to abut on the peripheral surface of the lower electrode 3 from the side through the pushing operation of the rod 28. Thus, the radius of the lower electrode 3 can be measured at the contact position.

The detection signal of the measuring device 26A is inputted to a central control device (not shown), and the central control device controls the operation of the measuring device 26A and the operation of the drive motor 14 of the elevation drive device 13. That is, the central control device drives the drive motor 14 of the elevation drive device 13 to lower the center of the lower electrode 3 to the reference position when replacing the lower electrode 3, and to change the peripheral surface position of the new lower electrode 3 after replacement. Is measured by the measuring device 26A, and based on the measured value and the distance from the center of the lower electrode 3 at the reference position to the height position of the upper peripheral edge of the lower electrode 3 at the predetermined welding position, It has a control content for calculating a rising amount of the lower electrode 3 and reversely driving the drive motor 14 of the lifting drive device 13 based on the calculated value to raise the new lower electrode 3 to a predetermined welding position. I have.

In this configuration, when the lower electrode 3 is replaced, when the "down start switch" attached to the central control device is turned on, the central control device drives the drive motor 14 of the elevation drive device 13 to turn on. By controlling the number of revolutions and lowering the slide table 4 via the transmission means 15, the center of the lower electrode 3 mounted on the slide table 4 is set at a predetermined reference position K (see FIG. 5). Descend to Here, the reference position K can be set to a height position at which the replacement work of the lower electrode 3 can be easily performed.
The distance H from the center O of the lower electrode 3 at the reference position K to the height position Y of the upper edge of the lower electrode 3 at the welding position is stored in the central control device in advance.

After the lower electrode 3 is replaced at the reference position K, when the "up start switch" attached to the central control device is turned on, the measuring device 26A is operated under the control of the central control device. Then, as shown in FIG. 5, the peripheral surface position of the new lower electrode 3 is measured, and the radius r of the lower electrode 3 is sent to the central control device as a measured value. The central controller calculates the input measurement value of the radius r of the lower electrode 3 from the distance H from the center of the lower electrode 3 at the reference position K to the height position Y of the upper peripheral edge of the lower electrode 3 at the welding position. By subtracting, the distance (Hr) for raising the lower electrode 3 is calculated, the number of rotations of the drive motor 14 corresponding to the distance (Hr) is calculated, and the drive motor 14 is calculated based on the calculated value. By controlling the number of rotations by performing reverse driving, the new lower electrode 3 is raised to a predetermined welding position via the raising drive of the slide table 4. Here, the lifting rod 23 constituting the transmission means 15 (see FIG. 4) does not move up and down unless the input shaft 19 is rotated by the driving of the driving motor 14.
, The ascending position is held via the slide table 4. Thereby, the movement adjustment to the welding position at the time of replacement of the lower electrode 3 is automatically performed, and the height position of the lower electrode 3 can be quickly and accurately adjusted.

As a modified embodiment of the first embodiment, the amount of wear of the lower electrode 3 is measured by the measuring device 26A in the control content of the central control device, and based on the amount of wear,
Control contents for driving the drive motor 14 of the lifting drive device 13 to raise the lower electrode 3 to a predetermined welding position may be provided.

In this configuration, when the "wear adjustment switch" attached to the central control device is turned on, the measuring device 26A operates under the control of the central control device, and the position of the peripheral surface of the lower electrode 3 is measured. The radius r of the lower electrode 3 is sent to the central control unit as a measured value. As shown in FIG. 6, the central control unit calculates the radius of the input lower electrode 3 from the radius R before wear of the lower electrode 3 stored by measurement at the time of replacement of the lower electrode 3 or at an arbitrary time. r is subtracted to calculate the number of rotations of the drive motor 14 corresponding to the amount of wear (Rr) of the lower electrode 3, and drive the drive motor 14 based on the calculated value to move the lower electrode 3 to a predetermined welding position. Up to Accordingly, the height of the lower electrode 3 can be easily adjusted according to the amount of wear not only at the time of replacement but also during welding work.

FIGS. 7 and 8 show a second embodiment of the lower electrode height adjusting mechanism in the resistance welding machine according to the present invention.
In this embodiment, instead of the measuring device 26A of the first embodiment,
A measuring device 26B for measuring the height position of the lower electrode 3 by contacting the upper edge of the lower electrode 3 from above is disposed.
3 is driven to lower the center of the lower electrode 3 to the reference position, and the height position of the upper edge of the peripheral surface of the new lower electrode 3 after replacement is measured by the measuring device 26B. Based on the calculated value, the distance to the height position of the upper edge of the peripheral surface of the lower electrode 3 at the predetermined welding position is calculated, and the drive motor 14 of the elevation drive device 13 is reversely driven based on the calculated value to form a new lower part. The control contents for raising the electrode 3 to a predetermined welding position are provided. Other configurations are the same as those of the first embodiment, and the same portions are denoted by the same reference numerals, and redundant description will be omitted.

The measuring device 26B includes an air cylinder 2
A detection arm 30 driven in the horizontal direction by the detection arm 30;
An air cylinder 31 for driving the whole of the air cylinder 29 and the detection arm 30 up and down and detecting the amount of up and down movement
The air cylinder 31 is provided with a support arm 27 '.
Is attached to the base frame 9 at a predetermined height position. The air cylinder 31 has a piston rod 32
The air cylinder 31 has a function of detecting a movement stroke of the motor and outputting a detection signal of the movement stroke.
Is preferably used. Further, the detection arm 30 extends to the lower front of the air cylinder 29, and has a tip portion provided with a touch sensor 3 for detecting contact with the peripheral surface of the lower electrode 3.
3 are provided. The detection arm 30 is normally held at a retreat position obliquely rearward which does not hinder welding work via the retreating operation of the air cylinder 29. It is provided so as to advance to a position above the lower electrode 3. The detection signals of the air cylinder 31 and the touch sensor 33 are input to a central control device (not shown), and the central control device controls the air cylinders 29 and 31.
Is system-controlled.

In this configuration, when the lowering start switch attached to the central control device is turned on at the time of replacement of the lower electrode 3, the central control device operates the lifting drive device 13 as in the first embodiment. By controlling the number of rotations by driving the drive motor 14 and lowering the slide table 4 via the transmission means 15, the center of the lower electrode 3 mounted on the slide table 4 is set in advance. Lower to the reference position. Then, the replacement work of the lower electrode 3 can be performed at the reference position.

Thereafter, when the "up start switch" attached to the central control device is turned on, the air cylinder 29 of the measuring device 26B is pushed out by the control of the central control device, and as shown in FIG. The tip of the arm 30 is pushed out of the retracted position to a position above the new lower electrode 3.
Next, the piston rod 32 of the air cylinder 31 is pushed downward, and the air cylinder 29 and the detection arm 3 are moved.
As a result, the tip of the detection arm 30 comes into contact with the upper edge of the peripheral surface of the new lower electrode 3. Since the touch sensor 33 is provided at the tip of the detection arm 30, contact with the lower electrode 3 is detected by the touch sensor 33, and a detection signal is sent to the central control device. In addition, the central control device is sequentially input with the movement stroke amount of the piston rod 32 detected via the measurement function of the air cylinder 31.
3 is stored as a measured value of the height position S (see FIG. 9) of the upper edge of the peripheral surface of the new lower electrode 3 at the time when the detection signal 3 is input.
In synchronization with this, the piston rod 3 of the air cylinder 31
2 is retracted, the entire air cylinder 29 and the detection arm 30 are raised, and the air cylinder 29 is further retracted to return the detection arm 30 to the retracted position.

Then, as shown in FIG. 9, the central control device determines a new value at the input reference position from the set value of the height position Y of the upper peripheral edge of the lower electrode 3 at the welding position stored in advance. The distance L by which the new lower electrode 3 is raised by subtracting the measured value of the height position S of the upper edge of the peripheral surface of the lower electrode 3
And the drive motor 1 corresponding to the distance L
4 is calculated, and the drive motor 14 is operated based on the calculated value.
, The new lower electrode 3 is raised to a predetermined welding position via the raising drive of the slide table 4, and the raised position is held by the stop control of the drive motor 14. Thereby, the movement adjustment to the welding position at the time of replacement of the lower electrode 3 is automatically performed, and the height position of the lower electrode 3 can be quickly and accurately adjusted.

In this embodiment, the touch sensor 33 is provided at the tip of the detection arm 30, but the touch sensor 33 is not always necessary and can be removed. In this case, the value when the detection signal of the movement stroke amount of the piston rod 32 input to the central control device does not fluctuate is changed to the height position S of the upper peripheral edge of the new lower electrode 3 at the reference position K. Is treated as a measured value.

In the first and second embodiments, a servo motor is used as the drive motor 14. However, the drive motor 14 only needs to be able to control the number of rotations. A pulse motor may be used, and the rotation of the geared motor may be detected by an encoder to control the number of rotations.

Further, the reference position for lowering the lower electrode 3 is desirably set to a height position at which the replacement operation of the lower electrode 3 can be easily performed, but it is not always necessary that the reference position is a position at which the replacement operation is performed. Instead, the replacement operation may be performed further downward and returned to the reference position again.

[0033]

As described above in detail, according to the lower electrode height adjusting mechanism of the present invention, the movement adjustment to the welding position when replacing the lower electrode is automated, and the height position of the lower electrode is adjusted. It can be adjusted quickly and accurately. Therefore, where the conventional visual adjustment was difficult,
It can easily cope with the case where the upper edge of the lower electrode is hidden by the work to be welded, and can easily adjust the height of the lower electrode even when the work to be welded is set. Has an effect.

Further, the amount of wear of the lower electrode is measured by a measuring device, and based on the amount of wear, a control content for driving the drive motor of the elevation drive device to raise the lower electrode to a predetermined welding position is a central control device. The height adjustment of the lower electrode according to the amount of wear can be performed not only at the time of replacement but also during welding work.

[Brief description of the drawings]

FIG. 1 is a front view of a height adjustment mechanism of a lower electrode in a resistance welding machine according to a first embodiment.

FIG. 2 is a plan view of a lower electrode height adjusting mechanism of the above.

FIG. 3 is a side view of a lower electrode height adjusting mechanism of the above.

FIG. 4 is a vertical sectional side view of a power jack constituting the transmission means.

FIG. 5 is an explanatory diagram showing the operation of the measuring device and the contents of calculation by the central control device.

FIG. 6 is an explanatory diagram showing the operation of the measuring device and the contents of calculation by the central control device in a modified example of the first embodiment.

FIG. 7 is a front view of a height adjusting mechanism of a lower electrode in the resistance welding machine according to the second embodiment.

FIG. 8 is an explanatory diagram showing the operation of the measuring device.

FIG. 9 is an explanatory diagram showing calculation contents by a central control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Resistance welding machine 2 Upper electrode 3 Lower electrode 4 Slide table 13 Elevating drive device 14 Drive motor 15 Transmission means 26A, 26B Measurement device w Workpiece

Claims (3)

[Claims] An object is provided with a rotatable disk-shaped upper electrode and a lower electrode, and a current is applied by sandwiching a workpiece with both electrodes, and continuous welding is performed on the workpiece by rotation of both electrodes. A resistance welding machine, comprising: a slide table provided with a lower electrode mounted thereon and capable of moving up and down; a drive motor capable of reversible rotation; and transmission means for converting a rotational motion of the drive motor into a linear motion. An elevating drive device for connecting one end of the means on the linear motion side to the slide table to raise and lower the lower electrode; a measuring device for abutting the peripheral surface of the lower electrode from the side to measure the peripheral surface position; At the time of replacement, while driving the drive motor of the lifting drive device to lower the center of the lower electrode to the reference position,
Measure the peripheral surface position of the new lower electrode after replacement with a measuring device,
Based on the measured value and the distance from the center of the lower electrode at the reference position to the height position of the upper peripheral edge of the lower electrode at a predetermined welding position, calculate the amount of rise of the lower electrode, And a central control unit having control contents for raising the new lower electrode to a predetermined welding position by reversely driving the drive motor of the lifting drive unit based on the calculated value. Height adjustment mechanism for lower electrode. A central control unit for measuring a wear amount of the lower electrode by a measuring device, and driving a drive motor of a lifting drive device to raise the lower electrode to a predetermined welding position based on the wear amount. The height adjusting mechanism of the lower electrode in the resistance welding machine according to claim 1, further comprising: 3. An electrode comprising a rotatable disk-shaped upper electrode and a lower electrode, and a current is applied by sandwiching the workpiece between both electrodes, and continuous welding is performed on the workpiece by rotation of both electrodes. A resistance welding machine, comprising: a slide table provided with a lower electrode mounted thereon and capable of moving up and down; a drive motor capable of reversible rotation; and transmission means for converting a rotational motion of the drive motor into a linear motion. An elevating drive device for connecting one end of the means on the linear motion side to a slide table to elevate the lower electrode, a measuring device for abutting the upper edge of the lower electrode from above to measure its height position, and a lower electrode At the time of replacement, while driving the drive motor of the lifting drive device to lower the center of the lower electrode to the reference position,
The height position of the upper edge of the peripheral surface of the new lower electrode after replacement is measured by a measuring device, and based on the measured value, the distance to the height position of the upper edge of the peripheral surface of the lower electrode at a predetermined welding position And a central control unit having a control content for raising the new lower electrode to a predetermined welding position by reversely driving the drive motor of the lifting drive based on the calculated value. Height adjustment mechanism of the lower electrode in the resistance welding machine.