JPS6321973Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to improvements in spot welding equipment.

[Background of the idea]

A conventional spot welding device has an upper electrode 12 and a lower electrode 14, as shown in FIGS.
are arranged to face each other, and each electrode 12, 14 moves toward or away from each other by a piston 16 sliding inside the gun cylinder 10, and the upper electrode 12
and the workpiece (object to be welded) interposed between the lower electrode 14
17 welding surfaces can be spot welded.
That is, as shown in FIG. 3, when the gun pressure release switching valve 18 is switched to the open state, air at the pressure set by the pressure regulating valve 20 is supplied to the air intake port of the gun cylinder 10. 22 and the yoke opening air intake port 24, the upper electrode piston 16 rises, and the yoke opening piston 26 descends. Therefore, the upper electrode 12 and the lower electrode 14
The electrodes move in the direction of separation, and each electrode becomes open. At this time, the spring 32 attached to the gun bracket 28 with the shaft 30 fixed thereto as a guide is in a compressed state as the bracket 34 is lowered.

Next, when the gun pressure release switching valve 18 is switched to the pressurized state, air from the pressure regulating valve 20 is supplied to the pressurized air intake port 36, and the lower cylinder chambers of the yoke release cylinder and the upper electrode cylinder are The air is discharged from the gun pressurization release switching valve. Therefore, the upper electrode piston 16 descends, the compressed spring 32 is expanded, the upper electrode 12 descends, and the lower electrode 14 rises. This movement causes the electrodes 12 and 14 to sandwich the workpiece 17, and spot welding is performed by energizing the workpiece 17.

However, rather than mechanically stretching the spring 32 and raising the bracket 34, the lower electrode yoke 38, and the lower electrode 14, the upper electrode piston 16
The lowering speed is faster, and the lower electrode side is heavier than the upper electrode side, so when the upper electrode 12 comes into contact with the workpiece, the reaction force causes the lower electrode 14 to rise. At this time, the upper electrode receives a downward force. Therefore, work 17
The workpiece 17 and the upper electrode 12 may not have sufficient rigidity.
If the workpiece 17 and the upper electrode 12 are not set perpendicular to the surface, or if the workpiece 17 and the upper electrode 12 are deviated from the perpendicular angle to the surface due to play in various parts, the lower electrode 14 may be lifted up from the position where the upper electrode 12 contacts the workpiece 17. Therefore, there was a problem that the position of the welding surface of the workpiece 17 and the position of the spot welding point were deviated from the normal position.

Therefore, in order to eliminate these problems, it is possible to minimize the positional deviation by bringing the lower electrode 14 as close as possible to the workpiece 17 and setting the spot position. If a robot or the like is used as a welding gun holding device, there is a risk that interference between the lower electrode 14 and the workpiece 17 may occur.
Furthermore, since the lower electrode 14 is also worn out due to the impact points, the above-described method is not sufficient to eliminate problems such as positional deviation.

In this manner, when performing spot welding with conventional equipment, the upper electrode piston 16 moves quickly and comes into contact with the welding surface of the workpiece before the lower electrode 14, and the reaction force lifts the lower electrode 14 and welds the workpiece 17. The shape follows the surface. Therefore, the following problems occur.

(1) When the lower electrode yoke 38 is lifted by reaction force, an impactful force is applied to the welding gun holding device (robot, etc.) 40 at each welding point, reducing the durability of the holding device 40 and causing problems in the long run. This may cause poor welding point position.

(2) If the rigidity of the welding surface of the workpiece is not sufficiently strong, the pushing force caused by the impact of the electrode side that first hit the workpiece will be succumbed to, and the electrode side that hit the workpiece will push a little and pinch the welding surface of the workpiece. The surface accuracy of the workpiece will be disturbed and the assembly accuracy of the workpiece will be deteriorated.

(3) If the welding surface of the workpiece is weakened by the inertia force due to the pressurization of the electrode on the side that comes into contact first, or if the welding surface of the workpiece is rigid, the welding gun holding device 40 will be defeated and the cylinder stroke of the gun cylinder will be excessive. Therefore, the workpiece 17 is pinched in this state, and the welding point position shifts from the normal position.

In addition, in order to reduce the influence of the above-mentioned defects, it is possible to reduce the influence by reducing the gap between the electrode that will later contact the workpiece welding surface and the workpiece welding surface with the electrode open as much as possible. However, there is a problem in that the gap between the workpiece and the electrode is small and interference is likely to occur.

[Purpose of invention]

The present invention was devised in view of the above-mentioned conventional problems, and its purpose is to provide a spot welding device that can prevent excessive force from being applied to the workpiece when pressurizing the workpiece with the upper electrode and the lower electrode. Our goal is to provide the following.

[Summary of the idea]

In order to achieve the above object, the present invention has a pair of electrodes disposed opposite to each other along the piston sliding direction, each electrode moving toward or away from each other by the piston sliding in the gun cylinder, and the upper In a spot welding device for spot welding the welding surface of a workpiece interposed between an electrode and a lower electrode, a plurality of cylinder chambers are formed in the gun cylinder, and a piston shaft is connected to the upper electrode in the first cylinder chamber on the workpiece side. The piston for the lower electrode, whose piston shaft passes through the third cylinder chamber and is connected to the lower electrode portion outside the gun cylinder, is inserted into the second cylinder chamber, and the piston for the lower electrode is connected to the lower electrode portion outside the gun cylinder. An auxiliary piston whose piston shaft is fixed coaxially with the piston shaft of the lower electrode piston is inserted into the cylinder chamber, and the load of the lower electrode part with respect to the gun cylinder support part and the supporting force of the auxiliary piston with respect to the lower electrode part are The lower electrode part is supported by applying counterbalancing pressure to the auxiliary piston, and equal pressure is applied to the reforming pistons in the first and second cylinder chambers so that each piston slides in opposite directions. shall be.

[Example of idea]

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

4 and 5 show the construction of a preferred embodiment of the present invention.

In FIGS. 4 and 5, the gun cylinder 50
The first to third cylinder chambers 52, 54, 56
is formed. An upper electrode piston 60 having a piston shaft 58 connected to the upper electrode 12 is inserted into the first cylinder chamber 52 on the work side. A piston shaft 62 is provided in the second cylinder chamber 54.
A lower electrode piston 66 that passes through the third cylinder chamber 56 and is connected to the lower electrode portion 64 outside the gun cylinder 50 is inserted. Furthermore, an auxiliary piston 70 having a piston shaft 68 fixed coaxially with the piston shaft 62 of the lower electrode piston is inserted into the third cylinder chamber 56 .

First cylinder chamber 52 and second cylinder chamber 54
are separated by a partition plate 72, and an electrode pressurized air intake port 74 communicating with the first and second cylinder chambers is formed within the partition plate 72. Further, electrode opening air intake ports 76 and 78 are formed in the first and second cylinder chambers 52 and 54, respectively.

The second cylinder chamber 54 and the third cylinder chamber 56 are separated by a partition plate 80, and an air opening 84 is formed in the top plate 82 of the gun cylinder 50. Balance air intake ports 86 and 88 are formed.

In this way, the gun cylinder 50 in this embodiment
has first to third cylinder chambers 52 to 56 formed therein, and is supported by the gun bracket 28 so that the piston sliding surface intersects with the horizontal axis.

As shown in FIG. 6, the device in this embodiment configured in this manner is designed so that the load of the lower electrode section 64 on the gun support bracket 28 and the supporting force of the auxiliary piston 70 on the lower electrode section 64 cancel each other out. The pressure adjusted to
The balance air is supplied to the auxiliary piston 70 via the balance air intake port 86. That is, the lower electrode portion 64 is balanced with respect to the gun support bracket 28 in a weight-free state. In this state, when the gun pressurization release switching valve 18 is switched to the open state, air at the pressure set by the pressure regulating valve 20 is supplied to the electrode release air intake ports 76 and 78, and the upper electrode piston 60 rises, and the lower electrode piston 6
6 descends. That is, at this time, when looking at the gun bracket 20 as a reference, the upper electrode 12 and the lower electrode 14 are in an open state.

Next, when the gun pressure release switching valve 18 is switched to the pressurized state, air is supplied to the electrode pressurized air intake 74, and the air in each cylinder chamber is transferred to the air intake 76,
78, and is discharged from the air release port 84. By supplying this air, the upper electrode piston 60 descends and the lower electrode piston 66 rises, causing the upper electrode 12 to rise.
and the lower electrode 14 approach the workpiece 17. At this time as well, the lower electrode section 64 is always in an unloaded state with respect to the gun support bracket 28. That is, the pressures are set by the pressure regulating valve 90 so that the pressurizing forces of the upper electrode 12 and the lower electrode 14 are balanced.

Since air of equal pressure is supplied to the upper electrode piston 60 and the lower electrode piston 66, the upper electrode 12 and the lower electrode 14 are connected to the workpiece 1.
7 and when each electrode comes into contact with the work 17, the pressing force from each electrode 12, 14 is applied to the work 17, and spot welding by each electrode 12, 14 is performed.

Here, there is a resistance difference between the upper electrode 12 and the lower electrode 14 and a difference in the distance from each electrode 12, 14 to the workpiece 17, so that it takes a long time for the upper electrode 12 and the lower electrode 14 to contact the workpiece 17. Even if there is a misalignment, the piston on the side that came into contact with the welding surface of the workpiece 17 first stops due to the slight resistance that came into contact with the workpiece 17, and the piston on the side with no resistance is pushed. Therefore, the welding surface of the workpiece 17 is connected to the electrodes 12 and 14 on both sides.
Almost no load is applied to the workpiece 17 until it is pinched.

In this way, the device in this embodiment is able to pressurize the welding surface of the workpiece without causing any reaction force even if one electrode hits the welding surface of the workpiece first. No force other than the weight of the welding gun is applied to the gun holding device due to pressurization. Furthermore, even if one electrode touches the welding surface of the workpiece earlier than the other electrode, the other electrodes will follow suit, so there is no need to apply too much pressure to the welding surface of the workpiece or the stroke of the pressurizing cylinder to be too long. , there is no shift in the welding point position.

[Effect of idea]

As explained above, according to the present invention, when the workpiece is pressurized by the upper electrode and the lower electrode, no unreasonable force is applied to the welding surface of the workpiece, and an even pressing force is applied to the workpiece by the upper electrode and the lower electrode. So,
Spot welding that follows the welding surface of the workpiece can be performed,
This has the excellent effect of improving welding quality.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a conventional device, Fig. 2 is a sectional view taken along the - line in Fig. 1, Fig. 3 is a pressure circuit diagram of the device shown in Fig. 1, and Fig. 4 is an embodiment of the present invention. FIG. 5 is a sectional view taken along the line - in FIG. 4, and FIG. 6 is a pressure circuit diagram of the apparatus shown in FIG. 4. 12... Upper electrode, 14... Lower electrode, 50...
...Gun cylinder, 52...First cylinder chamber, 5
4... Second cylinder chamber, 56... Third cylinder chamber, 60... Piston for upper electrode, 66... Piston for lower electrode, 70... Auxiliary piston.

Claims (1)

[Scope of utility model registration request] A pair of electrodes are arranged facing each other along the piston sliding direction, and each electrode slides toward or away from each other by the piston sliding inside the gun cylinder, and welds the workpiece interposed between the upper electrode and the lower electrode. In a spot welding device for spot welding surfaces, a plurality of cylinder chambers are formed in the gun cylinder,
The upper electrode piston, whose piston shaft is connected to the upper electrode, is inserted into the first cylinder chamber on the workpiece side, and the piston shaft passes through the third cylinder chamber and is inserted outside the gun cylinder into the second cylinder chamber. Insert the lower electrode piston connected to the lower electrode part with
An auxiliary piston whose piston shaft is fixed coaxially with the piston shaft of the lower electrode piston is inserted into the third cylinder chamber, and the load of the lower electrode part against the gun cylinder support part and the support of the auxiliary piston against the lower electrode part are The lower electrode part is supported by applying pressure that cancels out the force to the auxiliary piston, and equal pressure is applied to each piston in the first and second cylinder chambers to cause each piston to slide in mutually opposite directions. spot welding equipment.