JP3575588B2 - Electric pressurized resistance welding machine - Google Patents

Description

[0001]
FIELD OF THE INVENTION
The present invention belongs to the field of electric resistance welding machines, especially the field of spot welding guns (including C type and X type), stationary spot welding machines, projection welding machines, resistance seam welding machines, and more specifically, A linear guide is used for the press-type guide mechanism that opens and closes the movable electrode tip, and various unit parts that are unified according to the function of the welding machine are referenced to one common base or the rail body of the linear guide. The present invention relates to an electric pressurized resistance welding machine to be assembled.
[0002]
[Prior art]
Regarding the conventional spot welding gun, a spot welding gun using a linear guide system for a drive mechanism of a movable-side electrode tip is known. For example, this is the invention described in the specification and drawings of Japanese Patent Application Laid-Open No. 10-34346.
[0003]
In this type of conventional welding gun, a second gun arm corresponding to a first gun arm fixed to a gun body is provided by a pressure drive mechanism including a ball screw, a sliding nut, a linear guide, and a servomotor provided in the gun body. It is driven along the gun body, sandwiches the laminated plate (work) between the two electrode tips, applies the necessary pressure for welding, and applies a welding current to heat and join the local part.
[0004]
According to this type of conventional equipment, the number of parts that interfere with each other is smaller than that of conventional welding guns, so there are fewer restrictions on the movement path and welding position, and the stroke can be adjusted according to the size and shape of the workpiece. The gun arm can be freely rearranged each time it is different.
[0005]
[Problems to be solved by the invention]
However, since this type of conventional spot welding gun has a pressure drive mechanism integrally provided inside the gun body, these units must be used when a welding transformer or an equalizing device is integrated with the welding gun. Therefore, it was difficult to assemble or change the unit parts for each function of the welding machine with the current assembling method.
[0006]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem. The invention of claim 1 is to provide a gun arm having one electrode tip, a drive unit for driving the other electrode tip corresponding to the electrode tip, and a welding machine. to the welding unit to cancer bracket and / or the welding machine supports including welding transformer for supplying a secondary current in the resistance welding machine, each in one of the common base is configured to be attached removably to each type of unit the drive unit and the recessed section of the rail body having a linear guide rails disposed parallel to the sides, and a linear guide rail and a ball screw provided in parallel of the rail body, the ball screw nut block is incorporated, the other electrode tip is supported on the nut block side, the electric motor the ball screw By driving more rotation, the nut block is moved linearly, the linear movement the provided in the direction of the linear guide rail to said nut block is arranged to be guided, the common base length of the rail body Characterized in that it is arranged on the mounting surface in the direction and is detachably attached to the rail body.
[0007]
According to the first aspect of the invention, the following items can be satisfied.
(1) Assembling accuracy can be easily obtained.
(2) Since the rigidity is high and the weight can be reduced, followability at the time of welding is improved.
(3) Assembly and maintenance are facilitated.
(4) The electrode rotation prevention mechanism required when the guide center and the electrode pressing center are at offset positions is not required.
(5) Since the drive unit can use commercially available standard parts that can be mass-produced, the cost can be significantly reduced.
[0008]
According to the first aspect of the present invention, since both sides of the common base are used as the mounting reference planes, it is easy to mount and remove the equalizing unit, the gun arm, the welding transformer, and replace each of the reference units according to variations of the welding machine. And it can be made lightweight and compact.
[0009]
Next, in the invention of claim 2 , a linear guide rail is arranged in parallel on both sides of a rail body having a concave cross section, a ball screw is arranged in parallel with the guide rail, and a nut block is incorporated in the ball screw. On the nut block side, a gun arm having one electrode tip or a point holder having one electrode tip is supported, and by rotating the ball screw by an electric motor, the nut block moves linearly. In the drive unit in which the nut block is guided by the provided linear guide rail, whereby a pressing force is applied to the electrode chip, a gun bracket for supporting the drive unit on a robot is provided in a longitudinal direction of the rail body. And is detachably attached to the rail body. Lighted, the other gun arm having the other electrode tip corresponding to the electrode tip is characterized in that detachably mounted relative to the gun bracket or the rail body.
[0010]
This makes it possible to attach each unit such as a gun arm, gun bracket, equalizing unit, welding transformer, etc., based on the rail body, as compared to the conventional system in which the drive mechanism is integrated inside the gun body. A new design of the gun is not required, and in this case, the common base described above can be omitted, so that the reduction in size and weight can be promoted.
[0011]
According to the second aspect of the present invention, the structure can be simplified and the weight can be reduced by directly attaching the gun arm with reference to the gun bracket or the rail body.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a side view showing a first embodiment when the apparatus of the present invention is applied to a C-type servo spot welding gun. FIG. 2 is a view taken in the direction of the arrow Z in FIG. FIG. 3 is a view taken in the direction of the arrow A in FIG. FIG. 4 is a plan view showing an example of the drive unit. FIG. 5 is a view taken in the direction of the arrow Y in FIG.
[0013]
In the drawing, reference numeral 1 denotes a resistance welding machine, which is a so-called servo spot gun for a robot using a servo motor M for an actuator of an electrode. Reference numeral 2 denotes a C-shaped gun arm to which one electrode tip 3 is fixed at the tip. Reference numeral 4 denotes a drive unit for driving the other electrode chip 5 corresponding to the electrode chip 3. Reference numeral 6 denotes a common base on which various unit components are assembled, and is made of an aluminum-based material in consideration of weight reduction.
[0014]
7 is a welding unit. In this unit, a welding transformer T for supplying a secondary current to the welding machine and bus bars B1, B2 and B3 constituting a secondary circuit connected to the output terminals E1 and E2 of the transformer are movable. And a shunt F connected to the point holder H on the side.
[0015]
The drive unit 4 comprises a linear guide rail 9 in which the rail main body 8 has a concave cross section as shown in FIGS. 4 and 5, for example, and which is disposed parallel to both sides of the concave rail main body. In this case, a track surface U having a guide groove is formed inside the guide rail. A mounting surface d for mounting the common base 6 with bolts b1 is formed on the rail body 8 of this unit.
[0016]
A nut block N is incorporated in a ball screw 10 provided along a raceway surface U in a groove having a concave cross section of the rail body 8. The nut block N has a mounting surface c for the gun arm 2 formed thereon.
[0017]
An output shaft 12 of an electric motor M fixed to a housing 11 of the rail body 8 is directly connected to the ball screw 10. Further, in order to avoid the interference condition between the work and the electric motor as shown in FIG. 4, the electric motor M is folded back on the side surface of the rail body 8 and is connected via an arbitrary power transmission mechanism 16 such as a gear, a belt or a chain. It may be connected to the bolt screw 10.
[0018]
When the ball screw 10 is rotated by the power of the motor M, the nut block N moves linearly , and the other electrode tip 5 supported on the nut side faces the electrode tip 3 on one fixed arm side. Approaching or separating from each other, and this operation causes welding pressurization or electrode opening.
[0019]
In this case, the drive unit 4 is configured such that a drive device for pressurizing the gun is configured as one drive unit. The specific configuration thereof is, for example, as shown in the sectional view of FIG. A plurality of rolling elements br housed in the nut block N are sequentially rolled , and the nut block N is guided along a raceway surface of a linear guide rail provided in the direction of linear movement .
[0020]
On the common base 6, a gun arm 2 is fixed to one of the two surfaces thereof by a plurality of bolts b2 via an insulating plate, and a gun bracket 13 having a robot mounting surface on the same surface via the insulating plate. It is fixed by a plurality of bolts b3. A welding transformer T is fixed to the gun bracket 13 with a plurality of bolts b4.
[0021]
The drive unit 4 is fixed to one surface on the opposite side of the common base 6 by a plurality of bolts b1. A point holder H is fixed to the nut block N of the drive unit 4 with a plurality of bolts b5, and the other electrode tip 5 is supported at the tip.
[0022]
A cover (17 in FIG. 3) is provided on the rail main body of the drive unit in a direction in which the nut block N moves linearly . Dust, etc.).
[0023]
The cover 17 is the so cover the rails are arranged along the longitudinal direction of the rail body, both ends of the cover 17 on opposite sides of the housing of the rail body 8 is fixed.
[0024]
The cover 17 is a cover guide groove 21 so as not to interfere is formed when the nut block is moved along said rail to said nut block N. That is, the nut block N can move without any trouble as the cover plate 17 passes through the cover guide groove 21. This cover may be bellows.
[0025]
(Second embodiment)
Next, FIG. 6 shows a second embodiment of the apparatus of the present invention in the above-mentioned conventional spot welding gun for an X-type robot.
[0026]
In this case, the movable-side gun arm 15 corresponding to the fixed-side gun arm 14 fixed to the gun body is driven by a drive unit including the ball screw 10, the nut block N, the linear guide rail 9 and the servomotor M provided on the rail body. This point is common to the conventional welding guns, but the difference of the present invention is that the use of the common base 6 allows welding transformers, equalizing units, etc. in addition to the gun arm and drive unit to function according to welding conditions or work interference. It is easy to attach and remove according to conditions and the like.
[0027]
According to the welding gun in this case , the common base 6 has a substantially U-shaped cross section, and a fixed-side gun arm 14 is provided on one side of the lower surface of the common base 6 by a plurality of bolts b2 via an insulating plate. The rail body 8 of the drive unit 4 is fixed to the same surface by a plurality of bolts b1. The movable gun arm 15 is fixed to the nut block N of the drive unit 4 by bolts (not shown).
[0028]
The gun bracket 13 is fixed by a plurality of bolts b3 via an insulating plate with reference to both side plates of the common base, and the welding transformer T is firmly fixed to the gun bracket 13 by a plurality of bolts b4.
[0029]
In the drive unit fixed to the common base 6, the nut block N is incorporated in the linear guide rail (9 in FIGS. 4 and 5) and the ball screw 10 as shown in the above-described embodiment.
[0030]
The nut block N has a rolling element br such as a sliding element or a ball incorporated in a groove formed in the linear guide .
[0031]
In this guide unit, a plurality of rolling elements br roll sequentially along the raceway surface U or groove of the linear guide rail 9 by rotating the ball screw 10 by the electric motor M, and smoothly guide the movement of the nut block N. Then, the movable gun arm 15 is opened and closed by the movement of the nut block N.
[0032]
(Third embodiment)
Next, FIG. 7 shows a third embodiment in which the equalizing unit 18 is attached to the welding machine of the present invention. FIG. 8 is a view taken in the direction of the arrow X in FIG. 7, and a two-dot chain line shows the arrangement of the electric motor M folded back on the side surface of the rail main body as shown in FIG.
[0033]
In this case, the equalizing unit 18 includes a rod support plate 13b and a rod support plate in which both ends of two parallel guide rods 19a and 19b are fixed to the transformer base 13a of the gun bracket 13 at predetermined positions of the common base 6. 13c.
[0034]
The guide rods 19a and 19b can slide through bearings incorporated in housings 22a and 22b integrally or mechanically detachably mounted on the common base 6 by bolting or the like. It is supported by.
[0035]
The equalizing unit 18 includes a balancing cylinder 20 in which a cylinder body is fixed to a gun bracket 13, and a piston rod 21 of the cylinder is connected to a housing so as to obtain a weight balance effect of the gun body to the cylinder. With the pneumatic circuit described above, the entire gun is floated to absorb the reaction force when the movable electrode tip presses the work, thereby preventing the work from being deformed and distorted.
[0036]
Although the configuration example of the pneumatic circuit is omitted in the drawings of the present invention, for example, various operations such as increasing / decreasing internal pressure and / or switching directions are performed on the pneumatic circuit on the operating side and the pneumatic circuit on the return side of the balancing cylinder 20. A possible solenoid valve is provided, and air is supplied in a direction to cancel most of the weight load of the welding gun.
[0037]
For example, the fluid pressure adjustment to the cylinder is automatically performed by an ON / OFF switching operation of a solenoid valve by an external signal in a direction in which a weight balance is obtained according to a change in the gun posture by an electropneumatic proportional valve or the like. Done.
[0038]
(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to the following drawings.
FIG. 9 is a plan view of the device of the present invention. FIG. 10 is a side view of the entire apparatus. FIG. 11 is a view taken in the direction of the arrow Q. FIG. 12 is a view as seen from the arrow R in FIG.
In the figures, the same functional parts as those shown in the above-described embodiment (FIGS. 1 to 8) are denoted by the same reference numerals, and the details are omitted.
[0039]
The welding gun shown in the above drawing uses an electric motor M as a drive source of the electrode tip 5. One electrode tip 3 is fixed to the tip of a C-shaped gun arm 2. In the drive unit 4 for driving the other electrode tip 5 corresponding to the electrode tip 3, the gun arm 2 and the gun bracket 13 are directly attached to the rail body 8 by a plurality of bolts b2 and bolts b3 via an insulating plate. Can be In this case, the gun arm 2 may be directly attached to the gun bracket 13 side in an insulated form.
[0040]
A nut block N is incorporated in a ball screw 10 provided along the track surface in the rail main body. A gun arm (for example, 15 in FIG. 6) having the other electrode tip 5 or a point holder H is directly attached to the nut block by a plurality of bolts b5.
[0041]
A bus bar B3 is integrally formed on the point holder H in a form protruding from the point holder main body, and a bus bar B1 connected to an output terminal E1 of a welding transformer T for supplying a secondary current to the welding machine. A shunt F having flexibility corresponding to the linear movement of the nut block is connected between the bus bar B3.
[0042]
The ball screw 10 is connected via a coupling 22 to an output shaft of an electric motor M fixed to a housing 11 on one side of the rail body 8. As the electric motor M, a servomotor, a motor with a speed reducer, and the like are generally used.
[0043]
In this embodiment, the case where the output shaft of the servo motor and the ball screw 10 are directly connected is shown. However, if the electric motor M is elongated backward as described above, the output shaft is provided on the side surface of the rail body 8 as shown in FIG. It is folded back and connected.
[0044]
The inside of the nut block N plurality of rolling elements br is housed, rolled in turn a plurality of rolling elements br the raceway surface of the rail main body 8, to guide the nut block N in a direction in which the straight line movement.
[0045]
In the case of the present embodiment instead of the cover 17 of the above-described embodiment, an openable / closable box-shaped cover casing 23 for surrounding the entire sliding portion such as a track surface and a ball screw above the opening of the rail body 8. Is arranged. Although not shown in the drawing, the casing 23 is provided with an opening or an escape groove for avoiding interference with movable parts such as the bus bar B3, the electrode tip 5 and the point holder H which protrude outside the cover.
The drive unit can be protected from foreign matter, such as spatter, water, oil, dust, etc., generated during welding by housing the sliding portion in the cover casing 23.
[0046]
In the welding gun of this embodiment, the nut block N moves linearly by rotating the ball screw 10 with the power of the electric motor M as described above, and the other electrode tip 5 supported on the nut side. Move toward or away from the electrode tip 3 on one fixed arm side, and the welding pressurization or release is performed by this operation.
[0047]
Hereinafter, the operation of the present invention will be described with reference to FIG.
In the welding gun, control elements such as movement and positioning between welding spots, gun opening amount and acceleration / deceleration are taught in advance by a robot controller, and spot welding is performed by a reproducing operation thereof.
[0048]
Welding gun is moved to the welding point by the robot operation and strike position between the electrode tip is inserted, by a ball screw 10 and the electric motor M is operated by a command of the robot controller is rotated, the nut block N linear The workpiece moves linearly along the guide rail , sandwiches the workpiece between the movable electrode tip and the fixed electrode tip, applies the necessary pressure for welding, applies a welding current between the electrodes, and heats the welding point. Join.
[0049]
The welding operation is continuously performed for each welding point one after another by program control on the robot side. During this time, the robot operation and the electrode opening / closing operation of the welding gun are performed by synchronous control of the axis on the robot side and one axis on the gun side. It is performed efficiently with short welding tact time.
[0050]
If, for example, the production of multiple types of products on the same line is different, for example, due to changes in the work material, plate thickness or work shape, size, welding position, etc., the specifications such as the maximum pressing force, the corner size, the maximum opening stroke, etc. By changing the shape and size of gun arms and / or point holders, drive units (including selection of electric motor capacity), welding units, and other units of different sizes, from multiple units into target units The welding gun is assembled in accordance with welding conditions and work interference conditions.
[0051]
【The invention's effect】
As described above, according to the electric pressurized resistance welding machine according to the first aspect of the present invention, as compared with the conventional resistance spot welding gun, the pressure driving mechanism is integrally provided inside the gun body. without gun arm one common base reference, the drive unit, welding transformer, equalizing unit, because each of the normalized unit parts such as cancer bracket permits installation and removal, of these units components for each function as required Recombination becomes easy.
[0052]
According to the first aspect of the invention, all of the following items can be satisfied.
(1) Assembling accuracy can be easily obtained.
(2) Since the rigidity is high and the weight can be reduced, followability at the time of welding is improved.
(3) Assembly adjustment and maintenance work are facilitated.
(4) The electrode rotation stopping mechanism required when the guide center and the electrode pressing center are at the offset position is not required.
(5) Cost reduction can be achieved because commercially available standard products that can be mass-produced can be used.
[0053]
According to the second aspect of the present invention , as compared with the conventional electric spot welding guns of the C type and the X type, the drive unit is not integrated into the gun body, but based on the rail body of the linear guide unit. A gun arm, a welding transformer, a gun bracket, an equalizing unit, etc. can be replaced for each function-specific unit.
[0054]
This eliminates the need for a new structural design of a robot gun equipped with a welding transformer, and can eliminate the common base of claim 1 by directly attaching the gun arm to the gun bracket or the rail body, thereby simplifying the structure. And weight reduction can be further promoted.
[Brief description of the drawings]
FIG. 1 is a side view showing an outer shape of a welding gun according to a first embodiment when the apparatus of the present invention is applied to a C-type resistance spot welding gun.
FIG. 2 is a view as viewed in the direction of the arrow Z in FIG.
FIG. 3 is a view taken in the direction of arrow A in FIG. 1;
FIG. 4 is a plan view showing an example of a linear guide actuator including a drive unit according to the present invention.
FIG. 5 is an enlarged view as viewed in the direction of the arrow Y in FIG. 4;
FIG. 6 is a side view showing a second embodiment when the apparatus of the present invention is applied to another X-type spot welding gun.
FIG. 7 is a side view showing a third embodiment when an equalizing unit is provided in the apparatus of the present invention.
8 is a view as viewed in the direction of the arrow X in FIG. 7;
FIG. 9 is a plan view showing a fourth embodiment of the device of the present invention.
FIG. 10 is a side view of the entire apparatus of the present invention.
FIG. 11 is a view as viewed in the direction of the arrow Q in FIG. 10;
FIG. 12 is a view as seen from the arrow R in FIG. 10;
[Explanation of symbols]
1 .... resistance welding machine (servo spot welding gun for robot)
2 Gun arm 3 Electrode tip 4 Driving unit 5 Electrode tip 6 Common base 7 Welding unit 8 Rail body 9 ... Linear guide rail 10 ... Ball screw 11 ... Housing 12 ... Output shaft 13 ... Gun bracket 14 ... Fixed side gun arm 15 ... Movable side gun arm 16 ... Power transmission mechanism 17... Cover 18... Equalize unit 20... Balancing cylinder
H ... Point holder
M ... Electric motor
N ... Nut block
br ・ ・ ・ ・ ・ ・ Rolling element

Claims (2)

A gun arm having one electrode tip, a drive unit for driving the other electrode tip corresponding to the electrode tip, and a gun bracket for supporting the welding machine with a robot and / or a secondary current for flowing a secondary current to the welding machine. In a resistance welding machine in which a welding unit including a welding transformer can be attached to and detached from a common base for each unit , the drive unit has a concave section having linear guide rails arranged in parallel on both sides. and shape of the rail body, and a linear guide rail and a ball screw provided in parallel of the rail body, the nut block is incorporated in the ball screw, the other electrode tip is supported on the said nut block side is, by rotating the said ball screw by an electric motor, the nut block is linearly moved Its linear movement the provided in the direction of the linear guide rail to said nut block is arranged to be guided, the common base with the longitudinal direction of overlapping the mounting surface is arranged and the rail body of the rail body An electric pressurized resistance welding machine detachably mounted . Linear guide rails are arranged in parallel on both sides of the rail body having a concave cross section, ball screws are arranged in parallel with the guide rails , a nut block is incorporated in the ball screw, and one electrode chip is mounted on the nut block side. A nut arm or a point holder having one electrode tip is supported , and the nut block is moved linearly by rotating the ball screw by an electric motor, and the linear guide rail provided in the direction in which the nut block moves linearly. In a drive unit in which a nut block is guided, whereby a pressing force is applied to the electrode tip, a gun bracket for supporting the drive unit on a robot is disposed so as to overlap a longitudinal mounting surface of the rail body. And is detachably attached to the rail body. Flop and the corresponding other of the other gun arm having an electrode tip the gun bracket or electric pressurized resistance welding machine which is detachably attached with respect to the said rail body.

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