JP2001162379A - Double spot welding method and equipment - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] A single drive unit alternately or simultaneously generates torque for obtaining a pressing force required for welding between an intermediate electrode tip and an outer electrode tip, and multiple hit points. Enables welding. SOLUTION: An intermediate electrode tip (E1, E2) is arranged between one outer electrode tip and the other outer electrode tip (E3, E4) arranged on both sides, and the intermediate electrode tip faces the intermediate electrode tip. At least one of the intermediate electrode tip and the outer electrode tip is a rail 8 of the linear guide unit 3.
A driving ball screw 6 fixed to a linear motion rolling bearing 7 movable along the bearing and incorporated in the bearing is driven by an electric motor M.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of electric resistance welding, and more particularly to a portable spot welding gun for resistance spot welding machines and a spot welding gun for robots (C type, X type, with welding transformer, with equalizing unit). Etc.).

More specifically, when a plurality of welding heads are selectively used according to the size and shape of a work (object to be welded), and a double welding head is used to avoid locational restrictions depending on welding locations. In some cases, multiple welding heads are configured on a single gun body via intermediate electrodes, and a robot selects the target welding head according to changes in welding conditions and / or workpiece shape, etc., and uses a single motor to Provided is a double-point welding method and a double gun, which are useful when alternately or simultaneously press-welding multiple-points by generating torque for obtaining a pressing force required for welding to a plurality of welding heads.

[0003]

2. Description of the Related Art Conventionally, various types of welding guns used in a welding line of an automobile body are properly used in order to avoid welding conditions and work interference. The robot gun is generally switched by a command from a robot controller for each type of work.

A conventional welding gun of this type is provided with a plurality of welding heads on the left and right sides of a single gun body, and a so-called C-type dual gun in which the pressurizing method between the electrodes is a linear movement, and an intermediate arm. 2. Description of the Related Art A so-called X-type dual gun that drives a plurality of pairs of gun arms having a common electrode by rotating them around a support shaft is known.

The above-mentioned conventional welding guns are intended to be properly used depending on the welding location. For example, Japanese Patent Publication No. 47-45263, Japanese Patent Publication No. 55-39435, and Japanese Utility Model Publication No. 61-1986. No. 10867, Japanese Utility Model Application Laid-Open No. 53-149028, Japanese Utility Model Application Publication No.
No. 96725, Japanese Utility Model Application Laid-Open No. 62-105769,
Japanese Utility Model Application Laid-Open No. 62-118683 and Japanese Utility Model Application Laid-Open No. 63-165.
No. 80, Japanese Patent Application Laid-Open No. 11-300473, Japanese Patent Application Laid-Open No. 11-300474, and the like are well known.

[0006] Any of the above-mentioned conventional double guns is disclosed in Japanese Patent Publication No. 55-39435 and Japanese Patent Publication No. 47-452.
As disclosed in publications such as JP-A-63, one common gun arm is provided at the center, and two gun arms are arranged on both sides of the common arm. The gun arm is in an open state and is stopped, so that the gun arm on the side required can be appropriately selected and used.

[0007]

However, in the conventional C type welding gun described above, since the pressurizing method is a linear motion, the pressurizing cylinder is disposed on the left and right gun arms, so that the pressurizing cylinder moves rearward. It protrudes and becomes longer by the length of the protruding portion, so that there are many places where the location of the welded portion of the work is restricted.

On the other hand, the above conventional X type welding gun is
Since the movable gun arm is driven to pressurize around the rotation axis, the size of the gun arm on the opposite side from the electrode tip side, that is, the structure where the pressurization cylinder is connected to the rear end of the gun arm, has a dimension that is backward from the rotation axis of the gun arm. As a result, the work interference between the pressurizing cylinder and the gun arm occurs. In addition, the rear of the arm also opens and closes about the rotation axis, which places restrictions on the location.

As described above, in the conventional double point welding, a double air gun is mainly used, and not only the electrode stroke is limited by an air cylinder to narrow the condition width but also the miniaturization of the entire gun is limited.

A conventional double point welding using a servomotor as a pressurizing source is disclosed in, for example, Japanese Patent Application Laid-Open No. H11-300473.
JP, JP-A-11-300474, JP-A-11-300944
The inventions described in JP-A-320107, JP-A-11-320112 and the like are known.

However, a C-type welding gun driven by pressure with a servomotor requires a servomotor for each welding head. The X-type welding gun has two sets of welding heads arranged in opposite directions about a rotary drive shaft. That is, since the two sets of electrodes are arranged in two directions, for example, in a 90-degree direction or a 180-degree direction, the freedom of movement of the robot is restricted by the arm length of each set gun.

Further, as in the apparatus disclosed in Japanese Patent Application Laid-Open No. H11-320107, a chain wheel is provided on the rotation shaft of the X-type gun arm, and the movable-side gun arm is driven via a belt by a reduction gear of an electric motor. JP-A-11-32
As described in Japanese Patent Application Publication No. 0112, the apparatus for driving the movable gun arm on the reducer side via a swing lever and a link has a rotary drive mechanism and an X-type rotating portion of the gun arm, which are separately disposed. A connection mechanism or the like is required for the distance from the source, and the structural design becomes large, which is not desirable in realizing a lightweight and compact design.

According to the present invention, in the case of the C type, the outer electrode is arranged on both sides in the same direction as the arrangement direction of the intermediate electrode and the intermediate electrode around the rotation center of the speed reducer in the case of the X type. It is another object of the present invention to provide a double spot welding method and a double electric gun which can be press-welded alternately or simultaneously by one drive unit.

[0014]

Accordingly, the present invention has been developed to achieve the above-mentioned object, and employs the following technical means. That is, the invention of claim 1 is:
It has one electrode tip and the other electrode tip opposite to it, at least one of the electrode tips is driven to open and close, and after the work is clamped between the electrode tips, the pressure required for welding is reduced. When spot welding is performed by supplying a welding current, an intermediate electrode tip is disposed at a central portion between one outer electrode tip and the other outer electrode tip disposed on both sides, and the intermediate electrode tip is opposed to the intermediate electrode tip. At least one of the intermediate electrode tip and the outer electrode tip is fixed to a linear motion rolling bearing movable along a rail of a linear guide unit, and a drive incorporated in the bearing. The ball screw for driving is driven by an electric motor, thereby obtaining a pressing force required for the welding between the intermediate electrode tip and the outer electrode tip. Alternately or to generate simultaneously the torque to provide a double dotting welding wherein the contact pressure-welding by.

Next, the invention according to claim 2 is that the intermediate electrode tip is fixed to the base side of the gun bracket or the guide unit, and the one outer electrode tip is fixed to a bearing movable along the rail, Accordingly, the outer electrode tip is simultaneously operated from both sides of the intermediate electrode tip to perform pressure welding.

According to a third aspect of the present invention, the ball screw comprises a single left-handed screw and a right-handed screw, and the right and left screws incorporate linear motion rolling bearings, and each bearing has an outer electrode tip. The ball screws are arranged opposite to each other, and the ball screws are driven by the output of the electric motor, thereby driving the outer electrode tips from both sides of the intermediate electrode tip, and generating a torque for obtaining the pressing force required for the welding. A double point welding method characterized by simultaneously generating and pressure welding.

Further, according to a fourth aspect of the present invention, the intermediate electrode tip is fixed to a linear motion rolling bearing incorporated in the guide unit, and the outer electrode tip is fixed to a gun bracket or a base side of the guide unit. The intermediate electrode tip is driven in one direction by the rotation of the ball screw, and is driven in the opposite direction by the reverse rotation, thereby obtaining the pressure required for the welding between the left and right outer electrode tips. A double point welding method characterized by alternately generating torque and performing pressure welding.

According to a fifth aspect of the present invention, there is provided a linear guide including a linear motion rolling bearing movable along a rail on a base fixed to a gun bracket, and a driving ball screw integrated with the bearing. A drive unit including an electric motor for rotating the ball screw and driving the bearing along the rail, wherein the bearing is driven by an output of the electric motor, and an intermediate electrode chip provided on the bearing side. In an electric pressurizing device for generating a torque for obtaining a pressing force necessary for welding between outer electrode tips facing each other from both sides, an electrode of one of the intermediate electrode tip and the outer electrode tip is provided. The tip is fixed to the bearing side to form a movable electrode, and the other electrode tip is fixed to the gun bracket side or the guide unit side. A fixed electrode, to provide an electric pressure 圧複 guns, characterized in that the contact-pressure pressurized operating alternately or the outer electrode tip at the same time by the drive unit of the movable side electrode.

According to a sixth aspect of the present invention, there is provided an electric pressurized dual gun, wherein the electric motor is disposed on a side of the base of the guide unit opposite to the rail side.

According to a seventh aspect of the present invention, a speed reducer is incorporated in a main shaft portion for opening and closing two gun arms, and is fixed to a case side or an output shaft side of the speed reducer or to a gun bracket side supporting the speed reducer. And two intermediate arms supported on the case side of the speed reducer, on the output shaft side of the speed reducer, or on the side of the gun bracket supporting the speed reducer at an intermediate position between the two gun arms. An electrode tip provided on the two gun arms, and an electrode tip provided on the intermediate arm corresponding to the electrode tip, for transmitting a motor torque from an input shaft of the speed reducer, whereby the intermediate arm or the The two gun arms are operated alternately or simultaneously to generate a torque between the opposing electrode tips to obtain the pressing force required for welding to perform pressure welding. Providing double dotting welding method, characterized in that.

An eighth aspect of the present invention provides an electric motor for generating a torque for obtaining an electrode pressing force between opposing electrode tips provided at the tips of two gun arms, and an electric motor for generating a torque of the motor by an electrode tip of the gun arm. To communicate to
A drive unit comprising a speed reducer connected around a rotation center of the gun arm, wherein the motor is mounted on a common base, and the common base is supported on a case side of the speed reducer or on a gun bracket; The two gun arms are fixed to the case side or the output shaft side of the speed reducer or to the gun bracket, and an electrode tip corresponding to the electrode tip fixed to the tip of the two gun arms is provided between the two gun arms. One intermediate arm is mounted on the case side or output shaft side of the speed reducer or on the gun bracket side, whereby the intermediate arms are alternately connected to the drive unit or the two gun arms are simultaneously connected to one of the electrodes. Provided is an electric pressurized dual gun which performs a pressure operation and another electrode opening operation.

[0022]

[Operation] According to the method of the present invention, there is no need to arrange pressure cylinders on the left and right sides of a C type welding gun, and there is no longer a plurality of pressure cylinders protruding left and right rear as in the prior art. With a single drive unit, a plurality of electrode heads having a common intermediate electrode mounted on the unit can generate a pressing torque between the electrodes alternately or simultaneously. As a result, the overall size of the gun can be shortened, and the location of the workpiece weld is not restricted.

According to the present invention, the X-type welding gun has a reduction gear built into the rotating main shafts of two gun arms, and a plurality of electrodes having a common intermediate electrode around the rotation center are added by one drive unit. Welding can be performed by generating pressure. This eliminates the need to connect the pressurizing cylinder to the rear end of the gun arm, shortens the size of the gun arm rearward from the rotation axis, and thus makes it possible to reduce the size and freely control the opening angle of the electrode stroke. Further, since a plurality of electrodes can be arranged on the same side as the intermediate electrode, the freedom of rotation of the robot wrist by the arm length is not restricted as compared with the conventional gun in which two guns are arranged in the 90-degree direction.

Further, according to the present invention, by using one left and right screw for the electrode pressure driving device, pressure welding can be performed simultaneously from both sides of the intermediate electrode tip, and the welding tact time can be reduced. Shortening can be achieved.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a front view of a C type double head type welding gun having an intermediate electrode as a most preferred example for carrying out the double spot welding method of the present invention.
FIG. 2 is a view taken in the direction of the arrow A in FIG.

The dual gun 1 of the present invention is mounted on an industrial robot. Gun bracket 2 for supporting dual guns
Is supported by the wrist axis at the tip of the robot arm. As shown in FIG. 3, the base 4 of the linear guide unit 3 is detachably attached to the gun bracket 2 with bolts. A rail body 8 having a concave cross section is detachably attached to the base 4 by bolts. In the concave groove of the rail body, a ball raceway surface 9 (including a groove) on which a ball bearing br circulates and rolls is formed in a linear shape while maintaining a precise parallelism.

A bearing plate 5 is fixed to both ends of the base in the guide unit 3, a ball screw 6 is supported on the bearing plate 5, and is disposed in a concave groove of the rail body 8. The ball screw 6 has a linear motion rolling bearing 7
(Nut block) is incorporated. The bearing 7
Is moved along the ball raceway surface 9 on the rail by rotating the ball screw 6. On the bearing 7, an intermediate arm 10 common to the R / L side having intermediate electrode tips E1 and E2 or a chip holder is detachably attached by bolts B2.

The intermediate electrode tips E1 and E2 are connected to the intermediate arm 1
It is supported so as to protrude on both sides of 0, that is, left and right. Each electrode tip E opposed to each intermediate electrode tip E1, E2
Two gun arms 11 and 12 having 3 and E4 are arranged on both sides of the intermediate arm 10 and are fixed to the gun bracket side by bolts via an insulating plate.

Each pair of electrode tips E3 and E4, which form a pair with the intermediate electrode tips E1 and E2, uses a gun arm or a tip holder having a different hitting position or shape of each set of electrode tips according to welding conditions and work interference conditions. Is done.

The drive unit D includes a servo motor M for rotating and driving the ball screw 6 and a gear 13 fixed to one end of the ball screw 6 by the output of the servo motor M.
And a gear 14 fixed to the rotating shaft 16 of the servomotor M
The gears 13 and 14 are connected to each other via a power transmission mechanism 15 such as a timing belt, a gear, and a chain. The ball screw is driven to rotate by the torque of the motor. This drive mechanism can also be directly driven by directly connecting a servomotor to the speed reducer without using the power transmission mechanism 15 or the like.

The motor M is connected to the base 1 of the drive unit D.
7, which is arranged to be turned back below to avoid interference with the outside and to make the structural design compact.

As shown in FIG. 2, the welding transformer T is disposed between the two plates of the gun bracket 2 and is fixed by bolts.

Each output terminal Ta, Tb of the welding transformer T has a secondary conductor (a bus bar, a movable copper plate, etc.) for forming a current path between the intermediate arm 10 and the left and right gun arms 11, 12 between the positive electrode and the negative electrode. 18 and 19 are connected.

FIG. 4 is a schematic diagram for explaining the operation of the above embodiment. The same components as those shown in FIG. 1 are denoted by the same reference numerals. In the embodiment of FIG. 4, the positions of the welding points between the left and right electrode tips are on the same line. When the height of the hitting position is different on the left and right, it is easy to respond immediately as in the embodiment of FIG.

The welding point is preliminarily taught, and the recorded welding operation is reproduced by a robot to move the welding gun to a work set on a work jig. In this case, the intermediate electrode tips E1 and E2 stop at the opened position, the intermediate electrode tips E1 and E2 are inserted into the work W by the operation of the robot, and the welding point is positioned between the left and right electrode tips E3 and E4. Is done.

After the welding gun 1 is positioned on the work, the servo motor M of the drive unit D operates according to a command from the robot controller, and the ball screw 6 is rotated by the motor torque. The bearing 7 moves to the right. Intermediate electrode tip E1
Presses the work hitting point inserted between the right electrode tips E3, and a servo motor M between the electrode tips.
Then, a torque for the pressing force required for welding is generated, and a predetermined amount of welding current is supplied to perform spot welding.

Thus, when welding at the right hitting position is completed, the servo motor M rotates in the reverse direction, moves the bearing 7 to the left, opens the right welding position, and sets the intermediate electrode tip E2 to the left electrode tip. The work hitting position inserted during E4 is pressed.

Next, similarly, a necessary pressing force is generated between the electrode tips, and a welding current is supplied to perform spot welding.
In this manner, the intermediate arm 10 can be switched in the left-right direction by one drive unit D, and the left and right work hitting positions can be alternately welded by the intermediate electrode tips.

A method for controlling the positioning and moving speed of the electrode tip when the electrode tip is moved under pressure or opened and closed is, for example, a method in which the motor M is provided with a position sensor such as an encoder together with a speed sensor such as a tachogenerator. The number of rotations of the output shaft of the motor or the ball screw or the ball nut is converted into the number of pulses by an encoder, and the number of pulses is counted.
When the counted number of pulses reaches a set value corresponding to the moving distance of the electrode tip, the motor rotation is controlled at a timing to perform positioning. The moving speed is obtained by feeding back the signal from the tachogenerator, calculating the difference between the speed and the electrode position, and accelerating and / or decelerating the electrode to a predetermined speed to move the electrode to the workpiece welding position. The pressure control between the electrode tips is performed by detecting the armature current of the motor at the time of pressurization and feeding it back to control the pressure.

FIG. 5 shows a second embodiment. In this case, a right-hand thread 6a and a left-hand thread 6b are cut into the ball screw 6 of the guide unit 3, and the right-hand thread 6a and the left-hand thread 6b incorporate bearings 7a and 7b, respectively. . R / L-side gun arms 11 and 12 are fixed to the bearings incorporated in the left and right screws. The intermediate arm 10 is firmly fixed to the gun bracket 2 side (or the fixed side of the guide unit 3) at an intermediate position between the gun arms 11 and 12 arranged on the left and right.

The intermediate electrode tips E1 and E2 are fixed to the gun bracket 2 side or the base side of the guide unit 3 at an intermediate position with respect to the outer electrode tips. Therefore, the outer right and left electrode tips rotate the ball screw 6 by the drive unit D, so that the bearings 7a and 7b of the right screw portion 6a and the left screw portion 6b approach the intermediate electrode tips E1 and E2. As a result, the outer electrode tips E3 and E4 move from both sides of the intermediate electrode tip to the workpiece hitting point inserted in the intermediate electrode tips E1 and E2, and the two hitting points are simultaneously subjected to pressure welding. This makes it possible to double the shortening of the welding tact time as compared with the first embodiment.

FIG. 6 shows a third embodiment. In this case, a speed reducer 20 is incorporated around a rotation center for opening and closing the two gun arms 11 and 12, and the intermediate arm 10 is located at an intermediate position between the two gun arms. (Including the main body fixed side of the machine 20). The two gun arms 11 and 12 may have a cast structure in which the two arms are integrated, or may have a single arm structure in which each can be individually attached and detached.

FIG. 7 is a view taken in the direction of the arrow B in FIG. 6 and shows the structure for assembling the rotating part of the gun arm. The reduction gear 20 has an output shaft 21 penetrating from one side of a single-plate gun bracket 2, and two gun arms 11 and 12 are detachably attached to the output shaft 21 of the reduction gear by a plurality of bolts B <b> 1.

The intermediate arm 10 is disposed between the gun arms 11 and 12 as described above, and the arm support 10a is detachably attached to the tip of the gun bracket 2 by a plurality of bolts B2.

A drive unit D for driving the speed reducer 20 includes an electric motor M
The pulley 14 attached to the output shaft 16 of the motor and the pulley 13 attached to the input shaft of the speed reducer 20 are arranged in a box of a common base 17. 14 are connected by a mechanism 15 for transmitting motor power, for example, a timing belt, a gear, a chain, or the like.

The case base of the common base 17 and the speed reducer 20 has a number of bolts B from one side of the gun bracket 2.
3 collectively attached.

The intermediate arm 10 has a fixed electrode tip E
1, E2 are arranged on the left and right. The fixed-side electrode tips E1, E2
And the movable-side electrode tips E3 and E4 corresponding to. A gun arm 11 having the movable electrode tips E3 and E4,
Numeral 12 is fixed to a movable side component such as the case side of the speed reducer 20 or the output shaft 21. By rotating the case side or the output shaft side of the speed reducer 20 in one direction by the servo motor M, one electrode tip E4 performs a pressurizing operation, and during this time, the other electrode tip E3 is opened. When the servo motor M rotates in the opposite direction, the pressing / opening operation of each electrode tip is reversed.

As a result, the common intermediate electrode tip E
The speed reducer 20 alternately rotates the gun arms 11 and 12 with one drive unit D for 1 and E2 to perform spot welding alternately on the left and right strike points of the work set on the intermediate electrode tips E1 and E2. it can.

In the third embodiment, the intermediate electrode is mounted on the gun bracket side as a fixed side electrode, and the R / L side electrode tips E3 and E4 are mounted on the output side 21 of the reduction gear 20 as the movable side. showed that.

FIG. 8 shows a fourth embodiment. in this case,
This is an embodiment in which one intermediate electrode is driven as a movable side, and two gun arms 1 arranged on both sides of the other are used.
1, 12 are gun brackets 2 with a plurality of bolts B5.
Attached to. The intermediate arm 10 is detachably attached to the output side 21 of the speed reducer 20 by a plurality of bolts B4.

Therefore, the common intermediate electrode tips E1,
With respect to E2, the reduction gear 20 is rotated around the rotation center of the gun arms 11 and 12 by one drive unit D to swing the intermediate electrode tips E1 and E2 to the L side and the R side. Spot welding can be performed alternately on the work hitting positions positioned at E3 and E4, and the application range of the double gun can be further expanded and the practicality can be improved.

[0052]

As described above, according to the method of the first aspect of the present invention, the torque for obtaining the pressing force required for welding between the intermediate electrode tip and the outer electrode tip by one drive unit is obtained. Pressure welding can be performed alternately or simultaneously. As a result, the size and weight of the double gun can be reduced, and the electrode stroke can be arbitrarily controlled. Further, according to the present invention, the mounting structure of the compound gun can be standardized such as a drive unit, a linear guide, and a transformer unit, so that the design cost can be reduced and the mounting accuracy can be improved.

Next, according to the second aspect of the present invention, since the outer electrode tips can be simultaneously operated from both sides of the intermediate electrode tip to perform pressure welding, the welding speed at the multiple hit point position is increased, and the working efficiency is improved. It can be dramatically improved.

According to the third aspect of the present invention, a single left and right screw is used for the electrode pressing and driving device, and the left and right screws are driven by one electric motor, so that both sides of the intermediate electrode chip can be driven. Thus, the torque for the pressing force required for the welding can be simultaneously generated to perform the pressure welding at the multiple hit points. In this case, not only can a stable pressing force be obtained from both sides of the work, but also the speed of opening and closing between the electrode tips can be doubled to shorten the welding tact time.

Further, according to the invention of claim 4, either the intermediate arm or the two gun arms on both sides can be driven as a movable electrode under pressure as compared with a conventional rotary pressurized C-type compound gun. The drive mechanism can be easily changed according to the interference condition.

According to the double gun of the fifth aspect, since a plurality of pairs of welding heads including a common intermediate electrode are arranged on the linear guide, compared with the conventional C type double welding gun,
There is no need to connect a pressure cylinder to the rear end of the gun arm, and the size of the gun arm rearward from the rotation axis is reduced. Therefore, work can be shortened and assembly accuracy can be improved by assembling the linear guide unit and drive unit.
The size and weight can be reduced, and the electrode opening stroke can be arbitrarily controlled.

According to the sixth aspect of the present invention, the electric motor is disposed on the opposite side to the rail side of the base of the guide unit, so that interference with the outside can be avoided and the durability of the drive unit can be improved. I can do it.

According to the seventh aspect of the present invention, one reducer is incorporated at the center of rotation of the two gun arms,
Since the intermediate arm or the two gun arms can be alternately operated by transmitting the motor torque from the input shaft of the speed reducer to perform pressure welding, the conventional rotary pressurized X type dual gun can be used. The drive type can be easily changed according to changes in the work shape, etc., which diversify whether the middle arm of the book or the two gun arms on both sides is the movable side, so that the design cost can be reduced and the double gun The range of application can be expanded.

According to the apparatus of the present invention, the intermediate arm or two gun arms on both sides thereof are attached to the case side or the output shaft side or the gun bracket side of the speed reducer. The rotation method of the other gun arm can be changed according to the work shape or size of the pressed part. Therefore, at least three gun arms can easily cope with diversified variations of gun arms.

Further, since the arm rotating portion is constituted by one reduction gear as compared with the conventional X-type compound gun, a hinge for rotating the gun arm is not required, the structure of the driving mechanism is extremely simple, and the resistance of the rotating portion is reduced. Excellent spatterability and durability, and the opening stroke of the reduction gear can be selected directly and freely from the reduction gear. The amount of electrode displacement caused by the amount of electrode tip wear and the deflection of the gun arm is corrected and positioned. Control becomes easy and the condition range is expanded.

The assembly structure of the compound gun according to the present invention is composed of standard components such as a drive unit, a linear guide, and a transformer unit, so that the structure design is compact and the assembly accuracy is improved.

[Brief description of the drawings]

FIG. 1 shows a method for performing a double spot welding method according to the present invention.
C with intermediate electrode as the most preferred first embodiment
It is a front view of a double head type welding gun of a type.

FIG. 2 is a view as viewed from an arrow A in FIG. 1;

FIG. 3 is a sectional view showing a structural example of a linear guide unit.

FIG. 4 is a front view for explaining the operation of the first embodiment of the present invention.

FIG. 5 is a front view showing the structure and operation of a compound gun according to a second embodiment of the present invention.

FIG. 6 is a front view of an X-type compound gun showing a third embodiment of the present invention.

FIG. 7 is a view taken in the direction of arrow B in FIG. 6 showing the rotation mechanism of the compound X gun according to the present invention.

FIG. 8 is a front view showing a fourth embodiment of the compound X gun according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 double gun 2 gun bracket 3 linear guide 4 base 5 bearing 6 ball screw 7 bearing (nut block) 8 rail body 9 ball raceway surface 10 intermediate arm 11 gun arm 12 gun arm 13 gear 14 gear 15 power transmission mechanism (timing belt) 16 rotation Shaft 17 Base (common base) 18 Secondary conductor 19 Secondary conductor 20 Reducer 21 Output shaft D Drive unit M Servomotor T Welding transformer

Claims (8)

[Claims] 1. An electrode tip and another electrode tip opposite to the electrode tip, at least one of the electrode tips is driven to open and close, and a workpiece is sandwiched between the electrode tips. In a method of performing spot welding by supplying a necessary pressing force and a welding current, an intermediate electrode tip is arranged between one outer electrode tip and the other outer electrode tip arranged on both sides, and At least one of the intermediate electrode tip and the outer electrode tip among the opposed outer electrode tips is fixed to a linear motion rolling bearing movable along a rail of a linear guide unit, and is attached to the bearing. The built-in driving ball screw is driven by an electric motor, and thereby, a load required for the welding is provided between the intermediate electrode tip and the outer electrode tip. A double point welding method characterized by alternately or simultaneously generating torque for obtaining pressure and performing pressure welding. 2. The intermediate electrode tip is fixed to the gun bracket or the guide unit side, and one of the outer electrode tips is fixed to a bearing movable along the rail, whereby both sides of the intermediate electrode tip are fixed. 2. The double spot welding method according to claim 1, wherein the outer electrode tips are simultaneously operated to perform pressure welding. 3. The ball screw comprises one left-handed screw and one right-handed screw. Direct-acting rolling bearings are respectively incorporated in the left and right screws, and the outer electrode chips are arranged in each bearing so as to face each other. The ball screw is driven by the output of an electric motor, thereby driving the outer electrode tip from both sides of the intermediate electrode tip, and simultaneously generating torque for obtaining the pressing force required for the welding, thereby applying pressure. The method according to claim 1 or 2, wherein welding is performed. 4. The intermediate electrode tip is fixed to a linear motion rolling bearing incorporated in the guide unit, the outer electrode tip is fixed to a gun bracket or a base side of the guide unit, and the intermediate electrode tip is the ball. It is driven in one direction by the rotation of the screw and in the opposite direction by the reverse rotation, thereby alternately generating torque between the outer electrode tip and the outer electrode tip to obtain the required pressure for the welding. The double point welding method according to any one of claims 1 to 3, wherein pressure welding is performed. 5. A linear motion rolling bearing movable along a rail on a base fixed to a gun bracket, a guide unit including a driving ball screw integrated with the bearing, and rotating the ball screw. A drive unit including an electric motor for driving the bearing along a rail, wherein the bearing is driven by an output of the electric motor and an intermediate electrode chip provided on the bearing side and an outer electrode chip opposed to the intermediate electrode chip from both sides. In an electric pressurizing device for generating torque for obtaining a pressing force required for welding between the electrode tip and the electrode tip, one of the intermediate electrode tip and the outer electrode tip is fixed to the bearing side. The other electrode tip is fixed to the gun bracket side or the guide unit side so that the fixed electrode is fixed. The electric pressurized dual gun is characterized in that the movable side electrode is operated alternately by the drive unit or the outer electrode tip is operated simultaneously to perform pressure welding. 6. An electric pressurized dual gun according to claim 5, wherein said electric motor is arranged on a side of said guide unit opposite to a rail side. 7. A reducer is incorporated in a main shaft portion for opening and closing two gun arms, and two gun arms fixed to a case side or an output shaft side of the reducer or a gun bracket side supporting the reducer, At an intermediate position between the two gun arms, one intermediate arm supported on the case side of the speed reducer, on the output shaft side of the speed reducer, or on the gun bracket side supporting the speed reducer, and on the two gun arms. Having an electrode tip and an electrode tip on the intermediate arm corresponding to the electrode tip, for transmitting motor torque from the input shaft of the speed reducer, thereby alternately or alternately connecting the intermediate arm or the two gun arms. Double point welding, characterized in that torque is generated between the opposing electrode tips to operate simultaneously to obtain the required pressure for welding, and pressure welding is performed. Method. 8. An electric motor for generating a torque for obtaining an electrode pressing force between opposing electrode tips provided at the tips of two gun arms, and an electric motor for transmitting the torque of the motor to the electrode tips of the gun arm. A drive unit comprising a speed reducer connected around a rotation center of the gun arm, wherein the motor is mounted on a common base, and the common base is supported on a case side of the speed reducer or on a gun bracket; The two gun arms are fixed to the case side or the output shaft side of the speed reducer or to the gun bracket, and an electrode tip corresponding to the electrode tip fixed to the tip of the two gun arms is provided between the two gun arms. One intermediate arm is attached to the case side or the output shaft side of the speed reducer or to the gun bracket side. The intermediate arm electric pressure 圧複 guns performing electrode opening operation of the electrode pressurizing operation on one simultaneously actuated alternately or the two gun arms in the drive unit also on the other.