JPH0741424B2 - Spot welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The disclosed technology belongs to the technical field of the structure of an apparatus for welding a pair of metal panels and the like.

Thus, according to the present invention, a push-pull cylinder of an air cylinder type or the like having a pair of electrodes facing a work such as a pair of metal panels and the like, which are detachably provided at the ends, is used for reducing the pressure of a compressed air source or the like, such as an air hose. Connected through the actuation circuit,
The invention relates to a spot welding device in which a switching valve for control that alternately feeds compressed air to the pressurizing chambers of the push-pull cylinders is interposed in the operating circuit. A switching valve for supplying / discharging air or the like is provided at a predetermined portion of an operating circuit branched and connected to the pair of pressurizing chambers, and a pair of low pressure and high pressure switching valves are provided between the switching valve and the pressure source. The invention relates to a spot welding device in which a switching valve is provided and a low pressure control device such as a regulator and a high pressure control device are connected in series and are interposed in parallel.

<Prior Art> As is well known, mechanical devices often have a plurality of parts, and welding is widely used as a means for fixing and joining a plurality of parts. Among them, for example, So-called spot welding is used to join a pair of metal panels that weld a separator to an automobile fuel tank, and when a work is set and reset before and after welding, a pair of upper and lower electrodes are attached to the work. It is necessary to move away from each other.

As such spot welding technology with operation, for example,
Although a device such as Japanese Utility Model Laid-Open No. 55-49852 has been developed, the electrode is worn out due to repeated spot welding in order to provide a margin for the electrode to approach and separate from the work, and to set and reset the work with respect to the electrode. In order to deal with the above, a predetermined span is provided between the electrodes for dressing or replacement, and when performing spot welding, for example, the lower electrode is first brought into close contact with the lower surface of the work, and then the A so-called push-pull type gun has been developed in which the upper electrode is brought into close contact with the upper surface of the work, and the work is deformed due to electrode wear due to repeated high-frequency spot welding and uneven stroke span of the work. It is designed to deal with prevention, and in general, the upper and lower electrodes are attached to the tip of the gun of the corresponding push-pull cylinder,
The push-pull cylinder is connected to a pressure source such as a compressed air source through an operating circuit to perform spot welding.

Such a spot welding apparatus equipped with a push-pull cylinder will be briefly described with reference to FIGS.
, The gun push-pull cylinders 3, 3 '... are set up and down on the upper and lower frames 2, 2' ... and the electrodes 4, 4 '... .. are provided in the pressurizing chambers (not shown) above and below 3 '... so as to communicate with each other, and an operating circuit 5'through which float speed control valves 6, 6' ... A compressed air source as a pressurizing source by an operating circuit 9 in which an electromagnetic switching valve 7 for air supply and exhaust is provided in an operating circuit branched from the circuits 5, 5 '... And a regulator 8 of a pressure control device is provided. The separator 12 is connected to the fuel tank 11 of the automobile, and the separator 12 is superposed on the flange portion of the fuel tank 11 of the automobile and placed on the pedestal 13 and fixed by the clamp 14 to fix the work to the lower electrode 4'and the upper electrode. Interleaved between 4 and switching valve The actuator 7 is operated to supply compressed air to the pressurizing chambers of the push-pull cylinders 3 and 3'by the operation circuit 5 so that the electrodes 4 and 4'are brought into contact with the upper and lower surfaces of the work piece and energized to perform spot welding. Has been done.

The flowchart of the control of the spot welding apparatus 1 is as shown in FIG.

As a result of the repeated use of spot welding as described above, each electrode 4, 4'is consumed, and because of its replacement and dressing, each electrode 4, 4'is predetermined for the work. The spot welding is performed by the push-pull operation by providing the approaching / separating stroke, but the speed of the descending upper electrode 4 is higher than the speed of the ascending lower electrode 4 ', so that the upper surface of the work is generally The stroke span Δh of the lower electrode 4'to the lower surface of the work is made smaller than the stroke span h of the upper electrode 4, and furthermore, the upper and lower electrodes 4, 4 '... Contact the upper and lower surfaces of the work at the same time as much as possible. Thus, the float control valves 6, 6 '... are adjusted.

<Problems to be Solved by the Invention> Meanwhile, in the above-described conventional mode, the first electrode is used aside, but the electrode electrodes 4, 4 '... Are worn or replaced by spot welding during repeated use, dressing, etc. It is rare that the upper and lower electrodes 4, 4 '... Contact the upper and lower surfaces of the workpiece at the same time as designed due to a leak in the piping system of the operating circuit. Since the pressure of the air supplied by the switching valve 7 via 8 is constantly high, for example, 250 to 300 kg / cm ² , the lower electrode 4 ′ is moved earlier than the upper electrode 4 by the small stroke span Δh. The lower electrode 4'will come into contact with the lower surface of the work first.

Under such a design condition, the lower electrode 4 ′ naturally pushes up the lower surface of the work. To cope with this, the upper and lower push-pull cylinders 3,
It is designed such that the actuating circuit 5 is electrically connected to the pressurizing chambers 3 '... and the upper and lower electrodes 4, 4' ...

However, the length of the electrodes 4, 4 '... Is changed due to repeated spot welding, wear, repeated replacement, and dressing, and the operating circuit 5 changes with time.
In some cases, as described above, leaks may occur in the piping system of the above, and the operating circuit 5 causes the upper and lower push-pull cylinders 3,
Even though the lower electrode 3'is branched and conducted, the stroke span Δh of the lower electrode 4'for the work is shorter than the stroke span h of the upper electrode 4 for the work, so that the lower electrode is owing to the high pressure. Since 4 ′ comes into close contact with the lower surface of the work at an early stage and, moreover, impacts the work, the welded portion of the work may be deformed such as dented. There is a problem that the yield is lowered and the reliability of the product accuracy is not lowered as a result. Therefore, the number of dressings due to the consumption of the electrodes 4 and 4'is reduced, and the electrode 4 is not processed at an insufficient number of stages. 4 '
There was also the inconvenience of having to replace the.

The object of the present invention is to solve the problem of work deformation due to unbalanced shock contact with the work by the upper and lower electrodes of the push-pull type spot welding gun equipment based on the above-mentioned prior art as a technical problem to be solved. Even if one side of the pair of upper and lower electrodes comes into contact with one side of the work piece inadvertently, the work piece will not be shocked even if it unexpectedly comes into contact with the conventional control system. Therefore, it is an object of the present invention to provide an excellent spot welding apparatus that can be used as a result of which accurate and sound spot welding can be performed accurately and which is useful for the field of joining technology in the machine manufacturing industry.

<Means for Solving the Problems> In order to solve the above-mentioned problems, the structure of the present invention having the above-mentioned object as a gist in accordance with the above-mentioned object is provided with electrodes which are opposed to and close to a pair of works at the tip. In a spot welding apparatus in which each push-pull cylinder is branched and connected to a pressurizing source via an operating circuit in which a switching valve is interposed, a single supply / discharging switching valve and a low pressure source are connected to one pressurizing source. The high-pressure switching valve has a low-pressure control device and a high-pressure control device in series, and a technical means is provided so that they are connected in parallel.

<Operation> Then, the corresponding electrodes are attached to the guns of the respective push-pull cylinders so as to be close to each other with a gap for setting and resetting the work, and the respective push-pull cylinders are connected to each other through an operation circuit electrically connected to each other. Connected to a common switching valve for supplying / discharging air or the like, and a switching valve for low pressure and a switching valve for high pressure are connected to each of the circuits branching in parallel from the switching valve to the compressed air source. A low-pressure control device such as a regulator and a high-pressure control device are provided in series, and both operating circuits are connected to a pressure source such as a compressed air source, thus setting a work between a pair of electrodes. When each electrode is brought into close contact with the workpiece, the switching valve for supply / discharge is operated and at the same time the switching valve for low pressure of the parallel operating circuit that is branched and connected is operated to bring the pressure source to a predetermined low pressure via the low pressure control device. Step down Low-pressure fluid passes through the low-pressure switching valve,
It is sent to the pressurizing chamber of each push-pull cylinder through the supply / discharge switching valve, and even if one electrode comes into contact with one side of the work piece unexpectedly, the electrode comes into close contact with the work piece at low pressure. Therefore, even if the other electrode is in a proximity state where it does not contact the work, the welding part of the work is not deformed, and the operation circuit that conducts to both push-pull cylinders allows the other push-pull cylinder to be used as quickly as possible. Is activated and its electrode is brought into contact with the workpiece, the switching valve for low pressure and the switching valve for high pressure in the parallel operation circuit are switched, and the working fluid that has been made high pressure by the action of the regulator etc. is for the high pressure switching valve. Is applied to the pressurizing chambers of both push-pull cylinders via a switching valve for air supply and discharge, and both electrodes maintain the pressed contact state with the workpiece, and are energized to perform spot welding. After the spot welding is completed, the supply / discharge switching valve is opened, both push-pull cylinders are reset to face each other, and the low-pressure switching valve and the high-pressure switching valve of the branch parallel operation circuit are also switched. It is reset, the work is removed, the next work is reset, and the spot welding is repeated in this manner.

<Embodiment> An embodiment of the present invention will be described below with reference to FIGS.

It should be noted that parts that are the same as those in FIGS. 3 and 4 will be described using the same reference numerals.

1'is a spot welding apparatus which forms the subject of the present invention,
This is a mode for performing spot welding of the separator 12 to the fuel tank 11 of the automobile, that is, the frame 2,
2 '... Push-pull cylinders 3, 3' ...
Attached to the tip of the gun, and electrodes 4 and 4 ', respectively.
... is detachably attached.

In the corresponding pressurizing chambers (not shown) above and below the push-pull cylinders 3 and 3 ', an operating circuit 5 such as a high-pressure hose,
.. are connected to each other in a conductive manner, and an operation circuit 9 for branching and connecting the same is provided at a predetermined portion, and an electromagnetic supply / discharge switching valve 7 for air supply / discharge is provided at the base thereof. In the middle, a high pressure operating circuit 9'and a low pressure operating circuit 9 ", which are branched in parallel, are connected to the compressed air source 10 as a pressurizing source at the tip thereof.

Thus, the low-voltage operation circuit 9'which is branched and connected to the operation circuit 9 is provided with a high-voltage electromagnetic switching valve 15 and a regulator 8 as a low-voltage control device in series, and
A switching valve 15 'and a regulator 8'as a low pressure control device are electromagnetically connected to the low pressure operating circuit 9 "in series for low pressure and connected to a compressed air source 10.

The high pressure regulator 8 and the low pressure regulator 8'are each a high pressure air from the compressed air source 10, for example, 250 to 300 kg / cm ²
Is adjusted to 5-8 kg / cm ² and 1 kg / cm ² or less respectively to control the high pressure for pressure welding and the low pressure for proximity contact and send it to the high pressure switching valve 15 and the low pressure switching valve 15 ′. It is supposed to be paid.

In the illustrated mode, the flow control valves 6 and 6'are not provided in the actuation circuit 5'as in the conventional mode.

Further, in the illustrated embodiment, the lower electrode 4'is considered for the work taking into consideration the lifting process and the lowering process of the upper electrode 4 for the work, and the wear of the electrodes 4, 4 '... The stroke span Δh of the lower electrode 4 ′ is the stroke span h of the upper electrode 4
It is shorter than that.

In the above structure, as shown in the figure, the upper electrode 4 and the lower electrode 4'are set in the initial spot welding posture due to the contraction of the push-pull cylinders 3 and 3 ', and in that state, the fuel tank 11 and the separator 12 of the workpiece are placed. Are set in a pedestal 13 in a superposed posture, fixed by a clamp 14 and set in a predetermined posture between the electrodes 4, 4 '...
By switching on a control device (not shown), an air supply / discharge switching valve 7 and a high pressure switching valve 1
5. The low-pressure switching valve 15 'is switched from the posture shown in the figure, and the high-pressure air from the compressed air source 10 passing through the operating circuit 9 enters the branch-parallel operating circuits 9'and 9 ", respectively, and the high-pressure regulator 8 , And low pressure regulator 8 ', respectively, and the pressure is adjusted to a predetermined high pressure and low pressure.

However, in the high-pressure operating circuit 9 ', the high-pressure air is checked by the high-pressure switching valve 15, while in the low-pressure operating circuit 9 ", the low-pressure switching valve 15' is electrically connected. It reaches the supply / discharge switching valve 7 and is separated by the operating circuit 5 to form the upper and lower push-pull cylinders 3, 3 '.
Into the pressurizing chamber (not shown), each operates at low pressure.

Therefore, in the illustrated embodiment, the electrodes 4 and 4'are close to the work through the upper and lower push-pull cylinders 3 and 3 ', respectively, but the stroke span Δh of the lower electrode 4'with respect to the work is the upper side. Since it is shorter than the stroke span h of the electrode 4, the relatively lower electrode 4'promptly abuts the lower surface of the workpiece.

In that state, the upper electrode 4 is not yet close to the upper surface of the work.

However, since the high-pressure air from the compressed air source 10 is adjusted to a very low pressure by the low-pressure regulator 8'as described above, the lower electrode 4'abuts the lower surface of the work at an extremely low speed. No impact load is applied, so that no deformation occurs at the welded part of the work, and the upper electrode 4 moves down with the lower electrode 4'abutting against the lower surface of the work. The contact standby state is maintained in an attempt to approach the upper surface.

At the timing when the lower electrode 4'abuts on the lower surface of the work, the operating circuit 5 is branched and electrically connected to the pressurizing chambers of the upper and lower push-pull cylinders 3, 3 '... Even after the lower electrode 4'abuts on the lower surface of the work, the upper electrode 4 continues to descend and approaches, and contacts the upper surface of the work as soon as possible.

Here, the upper electrode 4 is provided by an appropriate sensor (not shown).
When the contact of the work piece with the work upper surface is detected, a high pressure switching valve 15 and a low pressure switching valve 1 of the high pressure operating circuit 9'and the low pressure operating circuit 9 "arranged in parallel via a control device (not shown).
5'is switched to the solid line state in the figure, and therefore the low pressure switching valve 15 'checks the low pressure operating circuit 9 ", and the high pressure switching valve 15 switches the predetermined high pressure air from the high pressure regulator 8 for supply and discharge. The valve 7 is brought into conduction, and the upper and lower electrodes 4, 4'are brought into contact with the upper and lower surfaces of the work.

Therefore, a high pressure is applied to the pressure chambers of the push-pull cylinders 3 and 3 ', and the upper and lower electrodes 4, 4' ...

After the spot welding is completed, the air supply / discharge switching valve 7 is switched from the solid line state shown in the figure by the control device, and the high pressure air from the high pressure switching valve 15 is switched to the air supplying / discharging switching valve 7. As a result, the electrodes are fed from the actuation circuit 5'to the opposite pressure chambers of the push-pull cylinders 3 and 3 ', the electrodes 4, 4' ... Are both rapidly separated from the work and reset to the initial state, and spot welding is performed. The formed work is removed, the next work is set as described above, and spot welding is performed as described above.

The flowchart during this period is as shown in FIG.

In this way, even if the upper and lower electrodes 4, 4'have different stroke spans with respect to the work and the lower electrode 4'approaches the work first, no deformation or the like occurs at the welded part of the work. All the workpieces are spot welded as designed, the product yield does not decrease, and the product accuracy can maintain reliability.

Needless to say, the embodiments of the present invention are not limited to the above-described embodiments. For example, the electrodes of the spot welding apparatus can be arranged not only in the upper and lower sides but also in a horizontal arrangement or a tilted arrangement. The mode of can be adopted.

Further, it is needless to say that the work to be applied is not limited to the fuel tank of the automobile and can be applied to other parts or metal panels of other industries.

<Effects of the Invention> As described above, according to the present invention, basically, when performing spot welding on a workpiece of a metal panel of an automobile, even if there is a difference in stroke span between the pair of electrodes facing each other, one electrode is different from the other. Even if the workpiece is brought into close contact with the work prior to the work, since the initial contact pressure is low, there is an effect that deformation or the like does not occur at the welded portion of the work. Therefore, the reliability of the product accuracy of the work is maintained. Not only is there an effect that can be achieved, but since the yield of parts is not reduced, the excellent effect that the cost can be reduced can be achieved.

In addition, since one or both electrodes do not need to be abutted against the work piece at an extremely high pressure, damage and wear of the electrodes are avoided, and the number of times of replacement and dressing is suppressed and the electrode The excellent effect that the durability is improved and the cost can be reduced also from this point is exhibited.

Thus, a high-pressure switching valve and a low-pressure switching valve, which have a high-pressure control device such as a high-pressure regulator and a low-pressure control device, are respectively provided between the switching valve and the pressurizing source, which are electrically connected to the push-pull cylinder. The initial proximity contact process of the electrode with respect to the work is performed by the low-pressure fluid, and after both electrodes contact the work, the electrode is substantially pressurized to be energized by the high-pressure fluid, so The spot welding by means of high energization is surely performed as designed, and also from this point, there is an excellent effect that the accuracy of the product is not deteriorated.

Further, even if a switching valve for high pressure and a switching valve for low pressure are provided from one pressurizing source, the pressure adjustment for the switching valve for low pressure can be performed from the high pressure side, and therefore, there is an advantage that no extra power is required. However, there is also an advantage that a complicated design and equipment are not particularly required since it is only necessary to interpose a conventional general switching valve in the operation circuit of the branch parallel connection.

[Brief description of drawings]

1 and 2 are explanatory views of an embodiment of the present invention.
FIG. 1 is a schematic mechanism diagram of a low-pressure device, FIG. 2 is a flowchart diagram thereof, FIG. 3 is a schematic mechanism diagram of a spot welding device based on a conventional technique, and FIG. 4 is a flowchart diagram thereof. 11, 2 ... Workpiece, 4, 4 '... Electrode 3, 3' ... Push-pull cylinder, 10 ... Pressurizing source, 7 ... Switching valve 5, 5 ', 9, 9', 9 " ...... Operating circuit, 1 '...
Spot welding equipment, 15 ′ …… Low pressure switching valve, 15 ……
Switching valve for high pressure, 8, 8 '... Regulator

Claims (1)

[Claims] 1. Spot welding in which each push-pull cylinder having a pair of electrodes opposed to and adjacent to a pair of workpieces at its tip is branched and connected to a pressurizing source through an operating circuit having a switching valve. In the apparatus, a low-pressure control valve and a high-pressure control valve are respectively connected in series to a supply / discharge switching valve and a pressurizing source, each having a low-pressure control device and a high-pressure control device in series. Spot welding equipment.