JP2001198680A - Electrode pressurization control method and apparatus for resistance welding machine - Google Patents

Abstract

(57) [Summary] [Purpose] With one type of spot welding machine, a stable pressing force is generated according to welding conditions such as plate thickness and material. When an electrode of a resistance welding machine is pressurized and driven by a pressurizing actuator, a cylinder chamber of the actuator is divided into a plurality of cylinder chambers, and fluid pressure supply and fluid pressure discharge to the plurality of separated cylinder chambers are performed by electro-pneumatic. O of proportional valve or solenoid valve
N, OFF, whereby the pressure generated in the actuator is variably controlled at a constant fluid pressure without increasing or decreasing the fluid pressure to the actuator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode pressure control system for a resistance welding machine, particularly a spot welding machine (for example, C-type and X-type models such as stationary welding machines, robot guns and portable guns). .

[0002]

FIG. 3 shows a conventional spot welding gun and its air circuit diagram. FIG. 4 shows a cylinder position at the time of pressurization / release in a conventional spot welding gun.

At the time of pressurizing operation, when the electrode pressurization is started after the electrode is opened, when the solenoid valve 1 is turned on, the air insertion port 3 is turned on.
Then, air is discharged from the air discharge port 2 to generate a propulsive force on the piston 35, and the rod 36 moves to the gun arm 37 side. Eventually, the rod-side electrode 38 approaches the electrode 39 mounted on the gun arm 37, substantially hits the work (not shown) set at the tip of the electrode 39, and applies pressure to the work welding point sandwiched between the electrodes. Occurs (FIG. 4b).

In the case where the electrode shifts from pressurization to release, when the solenoid valve 1 is turned off, air is inserted from the air insertion port 2 and discharged from the air discharge port 3, and a propulsive force is generated in the piston 35 and the cylinder 35 The rod 36 moves to the head cover 34 side. Eventually, the piston 35 hits the head cover 34 and stops. The stop position at that time is the opening amount between the electrodes
(FIG. 4a).

[0005]

However, the conventional cylinder has only one pressurizing chamber, and if it is desired to change the pressing force, it is necessary to change the air pressure to be inserted, so that the sliding speed of the piston changes. Occurs. Further, the variable range of the pressing force is narrow, and a single type of welding gun cannot cope with a portion having a different plate thickness or material.

[0006] In particular, with the spread of the manufacture of tailored blanks, which are made by butt-welding steel plates having the same thickness and the same material or different thicknesses and materials, the stamped parts from the tailored blanks are spot-welded. When assembling, the demand for welding machines that can handle a variety of pressing forces has increased, but conventional cylinder guns have been unable to cope.

[0007]

An object of the present invention is to provide an electrode pressurization control method capable of controlling a pressurizing force between electrode tips of a resistance welding machine in multiple steps, thereby enabling welding of different thicknesses and materials. Even under the same conditions, a single type of welding gun can be used, equipment costs can be greatly reduced, and the electrode pressing force can be varied according to the purpose even in an air cylinder like an electric motor, and welding quality can be improved. The electrode pressurization control method of the resistance welding machine.

[0008]

Therefore, the present invention employs the following technical means to achieve the above object. That is, according to the first aspect of the present invention, when the electrode of the resistance welding machine is driven to be pressurized by the pressurizing actuator, the cylinder chamber of the actuator is separated into a plurality of cylinder chambers, and fluid pressure is supplied to the separated cylinder chambers. The fluid pressure discharge is controlled by turning on and off the electropneumatic proportional valve or the solenoid valve, so that the pressure applied to the actuator at a constant fluid pressure without changing the fluid pressure to the actuator is adjusted to the welding conditions. The configuration is characterized in that variable control is performed in multiple stages in response.

A second aspect of the present invention is a pressure actuator for driving an electrode tip of a resistance welding machine by fluid pressure, wherein the actuator has a plurality of separated cylinder chambers, and each of the separated cylinder chambers has a plurality of cylinder chambers. Are provided with a piston, and a fluid pressure circuit connected to each of the cylinder chambers is provided with fluid pressure adjusting means for controlling the supply and discharge of fluid pressure in each of the cylinder chambers. A plurality of cylinders are rearranged by rearranging ON / OFF signals to the cylinder chambers, so that the pressing force generated between the electrodes is variably controlled in multiple steps according to the welding conditions such as the work plate thickness and work material. An electrode pressurizing device for a resistance welding machine, provided that the above conditions are satisfied.

The invention according to claim 3 is based on the condition that the cylinder chamber of the actuator is divided into upper and lower stages, and the separated cylinder is further divided into a plurality of parts by an intermediate wall.

According to a fourth aspect of the present invention, the actuator is characterized in that the pistons inserted into the respective cylinder chambers can move integrally with the two piston rods inserted into the upper and lower cylinders. And

A fifth aspect of the present invention is based on the condition that the fluid pressure adjusting means can be switched between ON and OFF by an external electric signal.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a sectional view of a pressurizing device of a spot welding gun and a structure of an air circuit diagram showing a preferred embodiment of the present invention. FIG. 2 shows the cylinder operating position of the present invention.

Reference numeral 10 in the figure denotes a main body case of the pressurizing actuator. The cylinder has a boundary wall 11 at the top and bottom.
The upper and lower cylinder chambers are further divided by an intermediate wall 22 into four upper and lower cylinder chambers.

In each of the four separate cylinder chambers, pistons 16, 17, 18, and 19, which can slide on the inner wall, are arranged, and each piston is composed of two pistons inserted concentrically with the upper and lower cylinders. The cylinders are integrally connected to rods 20 and 21, and each cylinder chamber has a rod side of the cylinder,
Air ports (air inlets and air outlets) are provided on the intermediate wall and the head side, respectively, and the above-mentioned pistons operate to form a pressurizing chamber and a return chamber in each cylinder chamber.

The two piston rods 20, 21 slide in such a manner that they penetrate the rod-side and head-side covers of the upper and lower cylinders in an airtight manner. Point holder 1 having movable electrode tip 14 at the tip of the two piston rods
5 is fixed.

Reference numeral 12 denotes a gun arm which is firmly fastened to the main body case side of the cylinder, that is, the rod side of the main body with a plurality of bolts. An electrode tip 13 facing the rod-side electrode tip 14 is fixed to the tip of the gun arm 12.

The two piston rods 20, 21 fixed to the point holder 15 pass through bearings fixed to the respective cylinders and move integrally. This eliminates the need for an electrode detent rod.

The fluid pressure circuit connected to the air source is provided with fluid pressure adjusting means 23 connected to the air port of each cylinder chamber and controlling the supply and exhaust of fluid pressure in each cylinder chamber. The adjusting means 23 includes a plurality of solenoid valves 2, 3, 4, and 5 corresponding to the four separation cylinder chambers.

The combination of ON and OFF of these two-way switching valves is changed in advance by issuing an electric signal which is set in accordance with the welding conditions for each series, thereby adjusting the pressure on the secondary side of the cylinder gun in multiple stages. It is configured so as to be possible.

The pressurizing operation of the apparatus of the present invention having such a configuration will be described with reference to the cylinder position diagrams of FIGS. 1 and 2. (1) When pressurizing with a pressing force A (N) from opening 0 (N), first, when the solenoid valves 1 and 2 are turned on, air is supplied from the air insertion port 7 and thrust is applied to the piston 16. Then, the piston rod 20 and the piston rod 21 move together to the gun arm 12 side. The pressing force in this case is obtained from the following equation. Pressure A (N) = Piston receiving area (cm ² ) x Air pressure (MPa)

Eventually, the movable electrode tip 14 is attached to the work set on the electrode tip 13 mounted on the gun arm 12.
Abuts the workpiece between the electrodes, and then a sufficient pressure is applied for welding.

(2) In order to generate a pressure of 2 × A (N), when the solenoid valves 1, 1, and 2 are turned on, air is inserted from the air insertion port 7 and the air insertion port 10. , A thrust is generated between the piston 16 and the piston 19, and the piston rod 20 and the piston rod 2
1 moves.

Eventually, the work set on the electrode tip 13 mounted on the gun arm 12 will be
Abuts and pressure is generated. In this case, since the number of pistons is two, the pressure receiving area is doubled, and the pressing force obtained between the electrodes is also doubled.

(3) In order to generate a pressure of 3 × A (N), the solenoid valve 1, the solenoid valve 2, the solenoid valve 3 and the solenoid valve 5 are
N, the air inlet 7, the air inlet 8, and the air inlet 1
Air is inserted from 0, and a propulsive force is generated in the piston 16, the piston 17, and the piston 19, and the piston rod 20 and the piston rod 21 move toward the gun arm 12 side.

Eventually, the electrode tip 14 comes into contact with the work set on the electrode tip 13 mounted on the gun arm 12, and pressure is generated. In this case, since the number of pistons is three, the pressure receiving area is tripled, and the pressure obtained between the electrodes is also tripled.

(4) In order to generate a pressure of 4 × A (N), when all the solenoid valves 1 to 5 are turned on, the air insertion port 7, the air insertion port 8, the air insertion port 9, the air insertion port 1
0, air is inserted into the piston 16, the piston 17, the piston 18, and the piston 19 to generate a propulsive force.
Moves.

Eventually, the electrode tip 14 comes into contact with the work set on the electrode tip 13 mounted on the gun arm 12, and pressure is generated. In this case, since the number of pistons is four, the pressure receiving area is quadrupled, and the pressure obtained between the electrodes is quadrupled.

When the gun is opened from the pressurization of the gun, when all of the solenoid valves 1 to 5 are turned off, air is inserted from the air insertion ports 6 and 11 and thrust is generated in the pistons 16 and 19. Then, the piston rod 20 and the piston rod 21 move to the intermediate wall 22 side. Eventually, the pistons 16 and 19 come into contact with the intermediate wall 22 and stop. The stop position at that time is the opening amount of the electrode.

Thus, the opening of the gun is completed. In addition,
In the embodiment of the present invention, a C-type spot welding gun is used as a model. However, the technical concept of the present invention is not limited to this. For example, an X gun, a stationary spot welding machine, a resistance seam welding machine, etc. Can be easily reproduced in the pressurizing device based on the inventive concept.

[0031]

As described above, according to the pressurizing control method of the first aspect of the present invention, the sliding speed of each piston does not change even if the pressing force is changed. Therefore, the setting range of the pressing force is widened at a constant fluid pressure without increasing or decreasing the fluid pressure of the pressurizing source. As a result, even if the welding conditions are changed, such as a member to be welded having a different thickness or a different material, a single type of resistance welding machine can cope with the change, and the welding quality can be improved.

According to the apparatus of the second aspect of the present invention, even if the thickness of the welding plate changes, such as two or three welding plates, a single welding machine can be used without using a plurality of regulators. , The pressure can be varied during the welding process,
A stable pressing force and welding current can be supplied during nugget generation, which is effective in preventing the occurrence of scattering during nugget generation and can greatly reduce equipment costs.

Next, according to the device of the third aspect, since the cylinder chamber is divided into a plurality, the pressing force can be arbitrarily selected by various combinations.

Next, according to the fourth aspect, the two piston rods inserted into the upper and lower cylinders can be moved integrally, so that the electrode rotation preventing mechanism becomes unnecessary.
The design structure near the electrodes is simplified.

According to the fifth aspect, since the fluid pressure adjusting means is switched between ON and OFF by an external electric signal, the switching operation of the pressing force is simplified, and the robot gun of a multi-product mixed production line is manufactured. It can also be applied to

[Brief description of the drawings]

FIG. 1 is a sectional view and an air circuit diagram showing a structure when applied to a pressurizing actuator of a spot welding gun as an embodiment of the present invention.

FIG. 2 is an operation explanatory view showing a cylinder operation position according to the present invention.

FIG. 3 is a conventional welding gun and air circuit diagram.

FIG. 4 is an explanatory view showing an operation position of a conventional welding gun.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pressurizing actuator 11 Boundary wall 12 Gun arm 13 Electrode tip 14 Electrode tip 15 Point holder 16-19 Piston 20 Piston rod 21 Piston rod 22 Intermediate wall 23 Fluid pressure adjusting means

Claims (5)

[Claims] When an electrode of a resistance welding machine is pressurized and driven by a pressurizing actuator, a cylinder chamber of the actuator is divided into a plurality of cylinder chambers, and fluid pressure supply and fluid pressure discharge to the plurality of separated cylinder chambers are performed. By controlling the ON / OFF of the electropneumatic proportional valve or the solenoid valve, the pressure applied to the actuator at a constant fluid pressure without increasing or decreasing the fluid pressure to the actuator is multi-step according to the welding conditions. The electrode pressurization control method of the resistance welding machine which is variably controlled. 2. A pressurizing actuator for driving an electrode tip of a resistance welding machine by fluid pressure, wherein the actuator has a plurality of separated cylinder chambers, and a piston is arranged in each of the separated cylinder chambers. ,
In the fluid pressure circuit connected to each of the cylinder chambers, fluid pressure adjusting means for controlling the supply and discharge of fluid pressure in each of the cylinder chambers is arranged, and the fluid pressure adjusting means turns ON and OFF the plurality of cylinder chambers. The condition is that a plurality of cylinders are rearranged by the rearrangement of signals, and thereby the pressing force generated between the electrodes is variably controlled in multiple stages according to welding conditions such as work plate thickness and work material. Electrode pressurizing device of resistance welding machine. 3. The electrode pressurization of a resistance welding machine according to claim 2, wherein the cylinder chamber of the actuator is separated into upper and lower stages, and the inside of the separated cylinder is further divided into a plurality by an intermediate wall. apparatus. 4. The actuator according to claim 2, wherein the pistons inserted into the respective cylinder chambers can move integrally with the two piston rods inserted into the upper and lower cylinders. 3. Electrode pressurizing device for resistance welding machine. 5. The electrode pressurizing device for a resistance welding machine according to claim 2, wherein said fluid pressure adjusting means is switched on and off by an external electric signal.