JPH0910957A - Method and device for correcting wear quantity of electrode for spot welding gun - Google Patents

Abstract

PURPOSE: To correct the wear loss of the tip of the fixed side electrode of a robot gun for spot welding to the standard position of the tip of an electrode tip in an initial stage without using an equalizer. CONSTITUTION: One electrode is supported by the tip of a gun arm 2, and the other electrode 6 is supported by a pressurizing driving shaft 4 installed at the rear end of the gun arm. A welding gun main body 1 pressurizing with the electrode, which converts the rotational motion of an electric motor 5 into a straight line motion, is made movable to a gun support member 14 by the pressurizing driving shaft through an electric motor 17 which is different from the motor 5, and the wear quantity of the electrode after dressing is detected. A welding gum main body is equipped with the correcting means 10 of the wear quantity of the electrodes, which controls the positioning of an arm side electrode by operating the motor 17 by a distance corresponding to the wear quantity of the electrode, which has been detected to a robot arm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resistance spot welding machine,
Especially, the spot wear amount of the fixed side electrode of the spot welding robot gun having the movable side electrode and the fixed side electrode (reduction margin)
And a device for correcting so as to match the initial reference position of the tip of the chip.

[0002]

2. Description of the Related Art If the tip of the electrode tip gradually deforms due to continuous welding points, it will affect the welding result, and therefore the tip tip shape must be corrected to the initial shape before that. Generally, the deformed electrode tip is dressed with a tip dresser, but the electrode position will deviate from the initial position by the amount corresponding to the amount of electrode wear after this shaping, and if the point is left misaligned, the work will be deformed. After dressing, it is necessary to correct the position of the electrode tip by the reduction amount.

Conventionally, when the wear amount of the electrode tip after dressing is corrected to the initial reference position of the tip of the tip, the wear amount of this electrode is detected, and the wear amount is calculated according to the wear amount.
A correction method has been proposed in which the entire gun is lifted by the robot side to position the fixed-side electrode.

As a conventional technique of this kind, for example,
JP-A-6-31460, JP-A-6-313274,
And Japanese Patent Publication No. 7-45109 is known. In these cases, in the robot control panel, in the case of the electric gun control panel, in addition to the movable side (rod side) electrode, the wear amount of the fixed side electrode tip also drives the robot side of 6 axes, that is, the robot arm. It is common to correct the position of the gun. Therefore, when the latest robot control panel as described above cannot be used, it is difficult to control the position of the fixed-side electrode with at least one axis controller.

[0005]

In view of the past tendency of electric guns, the fixed electrode drives the robot side arm without an equalizing device to prevent deformation of the work by using it as a backup of the work, and also to the arm side. It has been considered to use the electrode tip itself as one of the work receivers.

However, since the one-axis controller cannot correct the reduction allowance of the arm-side electrode, that is, the fixed-side electrode tip, an equalizer is required, but the direction and attitude of the gun are opposite to the effect of the equalize function. If freely changed, the spring force for weight balance will not work. In other words, even if the welding gun changes freely at various angles, such as downward, horizontal, and upward postures, the proper gun weight balance cannot be maintained each time.

Further, when the robot moves to the next hitting point, the welding gun must be fixed so as not to flutter. When the robot stops and the welding gun starts the electrode stroke operation, the fixing is released, but in this case, the fixed side electrode cannot back up the work.

[0008]

The problems to be solved by the present invention are as follows. With a 1-axis controller for an electric gun, it is not possible to correct the reduction margin due to electrode cutting after dressing the arm-side electrode without using an equalizer, so during electrode stroke operation, the workpiece to be welded on the arm-side electrode Contacting first and deforming the work piece. Also, when the gun posture changes downward, sideways, or upward for each hit point, a spring that cannot change the magnitude and direction of force cannot sufficiently cope with it. Moreover, when the electrode strokes, the gun moves up and down along the floating rod, causing the position of the spot welding flange part where the workpieces overlap to be misaligned.

[0009]

The present invention employs the following technical means to solve the above problems. That is, this is a method of correcting the tip reduction amount of the fixed side electrode of the spot welding gun having the movable side electrode and the fixed side electrode to the initial reference position of the tip side of the tip. Teaching is performed so as to match the tip reference position, the tip wear amount of the electrode from the tip reference position is detected after dressing of the tip, and the gun body or fixed side electrode is supported according to the detected wear amount. The main feature is that the moving gun arm is corrected and moved with respect to the robot arm that supports the gun body.

In the apparatus of the present invention, one electrode is supported at the tip of the gun arm, and the other electrode is supported so as to face a pressure drive shaft provided at the rear end of the arm. Supports a welding gun body driven by an electric motor so that the gun support member is movable from the output shaft of the motor through a clutch, detects the amount of electrode wear after dressing, and matches the detected amount of wear. The main feature is that the clutch is turned on and off for a certain distance to operate the entire welding gun to control the positioning of the arm-side electrode.

Further, one electrode is supported at the tip of the gun arm, and the other electrode is supported at the rear end of the arm so as to face each other, and the pressure drive shaft is an electric motor A. The driving welding gun main body is movably supported on the gun supporting member via an electric motor B different from the motor A, the electrode wear amount after dressing is detected, and the motor B is operated to operate the welding gun. There is provided a spot welding apparatus having an electrode reduction allowance correcting means for performing a positioning operation of the arm-side electrode by correcting the entire body by a distance corresponding to the detected wear amount.

Another main feature is that one electrode is supported at the tip of the gun arm, and the other electrode is supported at the rear end of the arm so as to oppose each other on a pressure drive shaft. The shaft supports a welding gun body driven by an electric motor so that the gun support member can move from the output shaft of the motor through a clutch, detects the amount of electrode wear after dressing, and turns on and off the clutch. Electrode reduction allowance correction means for performing positioning operation of the arm-side electrodes by operating the welding gun by a distance corresponding to the detected wear amount by rotating the screw shaft transmitted from the motor through the clutch. There is provided a spot welding apparatus having the following.

[0013]

In the method of the present invention, as shown in FIGS. 4A, 4B, and 4C, the tip of the new electrode, that is, the tip of the initial electrode tip is gradually deformed due to the continuous welding point and the welding result is affected. Since it is necessary to correct the tip shape of the tip to its original shape before coming, the electrode tip is dressed with a tip dresser as shown in FIG. After this dressing, as shown in Fig. B, a reduction margin occurs due to the dressing of the electrodes. Therefore, the robot moves to the reference position such that the robot touches the reference position preset by the phototube detector or the touch sensor. When the gun is moved and comes to a fixed position, the clutch or another electric motor is turned on from the robot side and the gun arm of the entire gun or fixed side electrode is raised. Next, when the tip of the electrode tip comes into zero contact with the reference position of the phototube detector during ascent as shown in FIG. C, the ascending of the fixed electrode is stopped by turning off the clutch or another electric motor. Therefore, even with a single-axis controller, ON / OFF control is performed to correct the fixed-side electrode by an amount commensurate with the wear amount of the electrode tip only after dressing, and the electrode positioning is completed.

Further, the apparatus of the present invention can use the fixed side electrode as a backup of the work, that is, as a fixed receiver without using the equalizing device and the correction control by the robot side, and the balance force for maintaining the posture change of the gun. Can solve the problem that the weight does not match the weight of the movable part and the rattling of the moving point at the next hit point.

For that purpose, it is necessary to correct the friction amount of the fixed side electrode, but in order to move the arm side electrode by using at least a uniaxial controller, a dimension commensurate with the cutting amount when dressing the electrode tip is used. The basic technical idea of the present invention is to use a separate motor or to lift the fixed side electrode from the pressurizing side electric motor side via a clutch.

Therefore, it is easy to correct the dressing amount of the movable-side electrode after dressing, and the fixed-side electrode, that is, the arm-side electrode may be corrected by moving the same size in the opposite direction. Electromagnetic brake is required because the electrode on the arm side must not move during pressurizing operation, but it does not rattle during robot movement, and positioning accuracy can be maintained sufficiently, and the electrode tip on the workpiece can be maintained. Since "zero touch" can be performed, work deformation can be prevented and the arm side electrode itself can be used as one of the work receivers. Also, the signal from the 1-axis controller to another motor or clutch is O
Since the correction operation can be performed while the welding gun is on standby even with the N and OFF signals only, it is possible to realize high accuracy by making the speed of the correction operation to a very small speed.

When the electrode pressurizing device and the electrode reduction allowance compensating device constituting the resistance welding machine are interlocked with one electric motor, the operation of the electrode reduction allowance compensating device is performed through the clutch from the motor. Thus, it is possible to correct and control the optimal electrode reduction allowance without any waste in the electrode movement.

Since the gun arm, the casing, and the unit parts of the electric motor can be easily removed by pulling out the screw shaft and the slide shaft of the electrode reduction amount compensating device forward from the gun supporting member, the assembling work and maintenance are easy.

[0019]

1 is a front view showing an apparatus for carrying out the method of the present invention. FIG. 2 is a view in the direction of arrow A, which is an intermediate cross-sectional view of the electrode reduction allowance correction device.

FIG. 1 shows the appearance of the entire C type electric pressure type spot welding robot gun. The structure of the gun arm 2 includes a portion that supports one electrode, that is, the fixed-side electrode 3, and a portion that supports the other electrode, that is, the movable-side electrode 6 that moves the pressure drive shaft 4 (including the ball screw) by the electric motor 5. Consists of.

The pressurizing drive shaft 4 is covered by a casing 7 and is unitized with a base member 8 for supporting the electric motor 5. In this case, the timing belt 9 in which the rotational force from the electric motor 5 is applied to the belt gear is accommodated inside the base member 8, and the ball screw nut N is rotated through this belt to move the pressurizing drive shaft 4. It moves forward and applies the pressure required for welding between the electrodes.

The electrode reduction allowance correcting device 10 has a positioning controller with an electromagnetic clutch 11 (including a clutch incorporating an electromagnetic brake 12 in this embodiment) directly attached to the output shaft of the motor 5 for fixing the fixed electrode. The positioning control operation is configured such that the entire gun 1 is moved with respect to the ball screw nut 16 fixed to the gun supporting member 14 by the rotation of the screw shaft 13 according to ON / OFF (start / stop signal) of the electromagnetic clutch 11. That is, the two slide shafts 15, both ends of which are fixed to the gun body 1, pass through the bearings of the gun support member 14 which is fixed to the robot side so that the entire gun is moved by the rotation of the screw shaft 13 described above. It is supported.

Next, FIG. 3 shows an example of another electrode reduction compensation device. In the above-described embodiment, an electromagnetic clutch is used as the electrode reduction allowance correction device, but in this example, the electrode reduction allowance correction device 10 has an electric motor 17 different from the pressurizing motor 5.
Is fixed to the base member 8, and the screw shaft 13 is directly connected to the output shaft of the electric motor 17.
Fixed to the gun support member 14 or ball screw nut 16
And two slide shafts 15 whose both ends are fixed to the gun support member 14 penetrate the bearings of the gun body and are supported so that the entire gun moves along the slide shafts 15. is there.

The positioning control operation of the fixed side electrode is performed by turning the electric motor 17 on and off (start / stop signal) to rotate or stop the screw shaft 13 to stop the ball screw nut 16 fixed to the gun supporting member 14 and to move the whole gun 1 Is moved by a dimension corresponding to the wear amount.

The operation of the apparatus of the present invention having such a configuration is shown in FIG.
It will be described based on. First, the gun of the device of the present invention is designed such that the operation and speed required for welding work are taught to the robot in advance, and the operation is reproduced in accordance with the taught program.

The operation sequence for correcting the electrode reduction allowance is that the tip of a new electrode tip is, for example, the photoelectric tube detector 1 in advance.
Teaching is performed so that the reference line corresponding to the chip reference position of the initial electrode by 8 is zero-touched.

Next, when the tip of the electrode tip 3 is gradually consumed and deformed through continuous welding work, in order to correct this, it is generally necessary to correct the tip shape of the electrode to the initial tip shape by the tip dresser 19 as shown in FIG. . In this shaping method, since the electrode 3 is positively cut or polished, the reduction amount gradually changes greatly.

Therefore, after the electrode tip shape is shaped as shown in FIG. B, the robot immediately moves the robot gun to a predetermined standby position, detects the electrode wear amount e after cutting, and reduces the electrode tip 3 The robot side outputs a gun rise signal so that the tip of the robot coincides with the tip reference position of the tip of the initial electrode of the phototube detector 18 provided at the predetermined position.

Then, the electromagnetic clutch 11 or the electrode position correcting motor 17 is turned on in response to the above signal as shown in FIG.
Then, the screw shaft 13 is rotated to lift only the gun body 1 against the gun support member 14 at a very low speed, and when the tip of the electrode tip 3 touches the reference line to zero, a signal for stopping the gun rise is output from the robot side. , With this output signal, the electromagnetic clutch 11 or the correction motor 17 is turned off,
The electrode reduction allowance correction is completed.

That is, when the tip of the electrode tip reaches the tip reference position of the phototube detector tube 18 by this operation,
The electromagnetic clutch 11 or another motor 17 for stopping this ascending operation is separated from the driving side, and the fixed side electrode is positioned at the chip reference position.

Although the C-type spot welding robot gun is referred to in the embodiments of the present invention, the technical idea of the present invention is not limited to this.
It is possible to easily change to various resistance welding machines such as a type robot gun to obtain the same purpose and effect.

[0032]

As described above, according to the method of the present invention, only the ON / OFF control by the electromagnetic clutch or the ON / OFF control of the electric motor can perform the correction movement according to the wear amount of the tip of the fixed electrode. Yes, electric motor A for pressurization
In addition to this, the configuration is simple by adding another electric motor B for compensating for the reduction of the electrode, and even in the case of the control by the one-axis controller by the electromagnetic clutch, only the ON / OFF control is added to the fixed side electrode. The amount of tip wear can be corrected simply by lifting only the gun body when the robot arm side is not driven as in the past and the welding position is very close.

Further, according to the apparatus of the present invention, the gun body can be easily removed from the gun supporting member by removing the slide shaft from the gun arm, and if necessary, the electrode reduction allowance correcting means is a unit of another floating exclusive mechanism. It can also be used by exchanging parts. In addition, the parts can be recombined and maintained easily.

[Brief description of the drawings]

FIG. 1 is a side view of the entire gun including a cross-section in an embodiment in which the method of the present invention is applied to a C type robot welding gun.

FIG. 2 is a view taken in the direction of arrow A in FIG. 1; .

FIG. 3 is a side view of a gun body in which another electric motor is used as a drive source of an electrode reduction amount correction device as another embodiment of the device of the present invention.

FIG. 4 is an explanatory diagram showing an electrode reduction margin correction operation sequence of the method of the present invention.

[Explanation of symbols]

 1 ... Robot gun body for spot welding 2 ... Gun arm 3 ... Fixed side electrode (arm side electrode) 4 ... Pressurizing drive shaft 5 ... Pressurizing electric motor 6 ... Movable side electrode (Rod side electrode) 7 ... Casing 8 ... Base member 9 ... Timing belt 10 ... Electrode reduction compensation device 11 ... Electromagnetic clutch 12 ... Electromagnetic brake 13 ... Screw shaft 14・ ・ ・ Gun support member 15 ・ ・ ・ Slide shaft 16 ・ ・ ・ Ball screw nut 17 ・ ・ ・ Electric motor for compensating the reduction allowance 18 ・ ・ ・ Phototube detector 19 ・ ・ ・ Tip dresser e ・ ・ ・ Electrode tip wear amount

Claims (5)

[Claims] 1. A method for correcting a tip reduction amount of a fixed side electrode of a spot welding gun having a movable side electrode and a fixed side electrode to a reference position of an initial tip end, the tip of an initial fixed side electrode. Teaching the tip so that it matches the tip reference position beforehand, and after dressing the tip, detect the tip wear amount from the tip reference position of the electrode, and according to the detected wear amount, the gun body or the fixed side A method for correcting the electrode reduction allowance of a spot welding gun in which the gun arm that supports the electrodes is corrected and moved with respect to the robot arm that supports the gun body. 2. One electrode is supported at the tip of a gun arm, and the other electrode is supported opposite to a pressure drive shaft provided at the rear end of the arm, and the pressure drive shaft is driven by an electric motor. The welding gun main body is movably supported on the gun support member through the clutch from the output shaft of the motor, the amount of electrode wear after dressing is detected, and the amount of wear is detected by a distance corresponding to the detected amount of wear. Clutch ON, OF
A method for correcting an electrode loss allowance of a spot welding gun, which performs F operation to move the entire welding gun to control electrode positioning on the arm side. 3. One electrode is attached to the tip of the gun arm, and the other electrode is oppositely supported to the pressure drive shaft at the rear end of the arm. The pressure drive shaft is driven by an electric motor A. The welding gun body is attached to the motor A on the gun support member.
It is movable via an electric motor B different from the above, detects the amount of electrode wear after dressing, and operates the motor B by a distance corresponding to the detected amount of electrode wear to move the entire welding gun. A spot welding apparatus equipped with electrode reduction margin correction means for performing positioning control of the arm side electrode. 4. One electrode is supported at the tip of the gun arm, and the other electrode is supported at the rear end of the arm so as to oppose each other, and the pressure drive shaft is driven by an electric motor. The welding gun body is movably supported on the gun support member through the clutch from the output shaft of the motor, the amount of electrode wear after dressing is detected, and the amount of electrode wear is detected by a distance corresponding to the detected amount of electrode wear. Clutch ON, OF
A spot welding apparatus having an electrode reduction allowance correcting means for performing an F operation and rotating the screw shaft transmitted from the motor through the clutch to move the entire welding gun to control the positioning of the arm-side electrode. 5. The control of the spot welding gun is performed by an independent control device, the clutch uses an electromagnetic clutch and an electromagnetic brake, and the clutch / brake control is performed by an external signal from the control device. Spot welding equipment.