JPH0735660Y2 - Air circuit for spot welding gun cylinder - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention relates to improvement of the electrode pressurization air circuit of a two-stage stroke cylinder of a welding gun, and particularly to reduce the shock at the time of electrode pressurization and the opening stroke between electrode tips. It relates to a welding gun two-stage stroke pressurized air circuit that is surely performed.

(Prior Art) The conventional electrode welding air circuit for a two-stage stroke cylinder used in a spot welding gun cannot move from the retract stroke to the welding stroke at one time. It was common to set it to a long stroke.

Recently, as a method of preventing a shock at the time of pressurization, a pressure reducing valve with a relief is provided in a return side air circuit of a pressurizing cylinder to apply a back pressure to the cylinder.

(Problems to be solved by the device) However, in this type of conventional air circuit, in addition to the electrode pressurization, a weak pressure of 2.5 kgf / cm ² is always applied to ensure the electrode opening force on the return side of the cylinder. Even if the electrode opening stroke is performed, if the electrode tip is welded to the work piece during the hold time when the opening force is small and the welding part is pressed even if the electrode opening stroke is performed, the electrode opening is not performed smoothly and the welding result is adversely affected. Will be affected.

Moreover, when increasing the welding speed by the robot, the transition speed from the retract stroke to the weld stroke could not be increased.

(Means for Solving the Problems) Therefore, the present invention takes the following technical means in order to overcome the above problems.

That is, a pressurizing device that constitutes a two-stage stroke cylinder of a spot welding gun that performs a retract stroke and a weld stroke by a pressurizing piston and a stroke switching piston that encloses the pressurizing piston and has one side open. In the above, a solenoid valve is provided in each of the working side air circuit, the return side air circuit, and the pressurizing side air circuit of the cylinder so that a back pressure is applied when the retract stroke is switched to the weld stroke. An air circuit for a spot welding gun cylinder, which is equipped with a relief valve.

(Operation) In the present invention, since the relief valve is provided in the air circuit on the return chamber side of the cylinder, when the electrode is moved from the retract stroke to the weld stroke,
The air pressure on the return side of the cylinder is reduced to a weak pressure, enabling high-speed transfer. Also, when the electrode is opened after welding is completed by installing a solenoid valve in the return side air circuit, even if the source pressure with a large opening force enters the return chamber and the electrode tip welds, it will be released and ensured. It can be opened to

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a large-diameter cylinder that constitutes a two-stage stroke cylinder, and 2 is a small-diameter cylinder that airtightly slides on the inner diameter of the large-diameter cylinder 1 to form an open-stroke working chamber A. Reference numeral 3 denotes a piston that slides airtightly on the inner diameter of the small diameter cylinder to form a pressurizing chamber B and a return chamber C for the welding stroke. Reference numeral 4 denotes a piston rod integrally connected to the piston 3, which penetrates the small diameter cylinder. The small diameter cylinder 2 can slide airtightly on the outer circumference of the rod. Reference numeral 5 denotes an equalizing mechanism for supporting the welding gun, which equalizes the spot welding gun by the reaction force at the time of pressurization and balances the applied pressure so as not to deform the object to be welded between the electrodes. Reference numeral 6 is an opening solenoid valve, 7 is a stroke switching solenoid valve, and 8 is a pressurizing solenoid valve. 9
Is a relief valve, 10 is a pressure reducing valve, 11 is a gun arm, 12,
13 indicates an electrode part.

The figure shows a state in which the electrode portion is opened up to the retract stroke. In this case, the opening solenoid valve 6 and the stroke switching solenoid valve 7 are OFF, and the pressurizing solenoid valve 8 is also OFF. The air taken in from the conduit a of the air source 14 flows to the conduit b on the secondary side with the pressure set via the pressure reducing valve 10, and passes from the pressurizing solenoid valve 8 through the conduit c to the opening solenoid valve 6. Via the pipe line d, it enters the return chamber C of the large diameter cylinder 1 and moves the small diameter cylinder and the piston to the end of the retract stroke to open the electrode.

In this state, when the opening solenoid valve 6 is turned on, the air passes through the pipeline g connected to the pipeline b on the secondary side of the pressure reducing valve 10 and travels from the stroke switching solenoid valve 7 to the pipeline e for a large amount. At the same time as the piston 3 and the small diameter cylinder 2 are integrally moved forward to the left in the working chamber A of the large diameter cylinder 1, the air exhaust of the return chamber C of the large diameter cylinder is throttled by the relief valve 9 and discharged into the atmosphere. During this time, the electrode moves forward at the relief set speed, moves from the retract stroke to the weld stroke, and shifts to a short welding work stroke.

For the welding operation, the solenoid valve 6 for opening is turned off and the solenoid valve 8 for pressurizing is turned on.
When is turned on, air is sent from the solenoid valve 8 for pressurization to the pressurization chamber B through the conduit f and the air passage of the piston rod. The air pressure in the return chamber C of the small-diameter cylinder 2 becomes 0 kgf / cm ² , the piston 3 moves forward, the electrode 12 comes into contact with the object to be welded, and the electrode pressure starts. Then, the welding current is completed by applying pressure for a certain period of time. The one-by-one welding is performed by the ON / OFF switching operation of the pressurizing solenoid valve 8.

Next, when opening the distance between the electrodes to the retract stroke, if the stroke switching solenoid valve 7 is turned off, the air in the working chamber A is opened to the atmosphere, and the air having the opening pressure set in the return chamber C is sent. Even if the electrode portion is in a welded state, it can be released with a sufficient opening force, and the electrode opening operation can be reliably performed.

As described above, according to the present invention, since the relief valve is provided in the air circuit on the return side of the two-stage stroke cylinder of the spot welding gun, when the electrode is moved from the retract stroke to the weld stroke, the electrode is driven at high speed. Can be moved with. Further, by providing an opening solenoid valve in the return side air circuit, when the electrode is opened after welding is completed, the original pressure is applied to the return side, and the large opening force of the original pressure ensures the electrode opening operation.

[Brief description of drawings]

The figure is a spot welding gun cylinder air circuit diagram showing an embodiment of the present invention. [Explanation of symbols] 1 ... Large diameter cylinder, 2 ... Small diameter cylinder, 3 ... Piston, 4 ... Piston rod, 6 ... Opening solenoid valve, 7
...... Stroke switching solenoid valve, 8 …… Pressurizing solenoid valve, 9 …… Relief valve, 10 …… Reducing valve, 12,13 ……
Electrode part

Claims (1)

[Scope of utility model registration request] 1. A two-stage stroke cylinder of a spot welding gun for performing a retract stroke and a weld stroke by a pressurizing piston and a stroke switching piston that encloses the pressurizing piston and is open on one side. In the pressurizing device, a solenoid valve is provided in each of the working side air circuit, the return side air circuit, and the pressurizing side air circuit of the cylinder so that back pressure is applied when the retract stroke is switched to the weld stroke. An air circuit for a spot welding gun cylinder, which is equipped with a relief valve on the side air circuit.