JPS6032549B2 - Welding electrode pressure control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved welding electrode pressurization control device for single-phase AC type or three-phase low frequency type spot welding machines.

When applying pressure to the welding electrode of a spot welder, the control method for the electrode pressure varies depending on the material of the workpiece.

Generally, in spot welding of aluminum (alloy), a so-called two-stage pressurization method is often used in which the electrode pressurizing force is changed during the current application period.

In this type of two-stage pressurizing method, as shown in Figure 2, a high initial pressurizing force is applied before energization, which improves the compatibility between the workpiece and the electrode and prevents the occurrence of "splashing". Forging pressure is applied again after energization to prevent welding defects such as flow holes and cracks.

Regarding the control of this electrode pressing force, when lowering the electrode, it is lowered by the weight of the piston of the cylinder or the electrode, and the welding pressing force is the pressure difference between the pressure set in the upper and lower chambers of the air cylinder. The initial pressurizing force and forging pressurizing force are usually obtained by removing air from the lower chamber of the air cylinder to obtain a high pressurizing force.

However, with this type of two-stage pressurization type, the descending speed changes depending on conditions such as the size of its own weight, that is, the weight of the electrode and piston, and the size of the frictional resistance of the packing, etc. In this case, the electrode descends at a faster speed and bounces on the workpiece, often damaging the electrode surface and the workpiece surface.

Therefore, a method of intervening a known speed control valve or the like to slow down the descending speed when the electrode descends is considered, but this would require removing the back pressure from the air cylinder and then removing the air from the lower chamber of the cylinder in order to apply forging pressure. Even if they try, they cannot be pulled out quickly, and as a result, the exhaust becomes clumsy, and as a result, it is not possible to pressurize the forging immediately after welding, the welded part cools down, and it becomes impossible to remove the welding defects described above. I can't stand it.

In short, the reality is that the descent speed cannot be appropriately controlled using the self-weight descent method.

Therefore, the present invention gradually reduces the exhaust pressure when the welding electrode is lowered, so that the welding electrode is lowered gradually, thereby preventing the generation of dents on the pressurized object (workpiece) and damage to the welding electrode. The purpose is to provide a pressurization control device for welding electrodes that can control the forging pressure without impairing the rising speed of the forging pressure. A flow control valve with a throttling function is installed, and the electrode ascending impulse line leading to the lower chamber is not only used for rapid exhaust, which is generally used, but also for the purpose of supplying pressure to the upper chamber of the diaphragm. They are characterized by the interposition of rapid exhaust valves that can gradually reduce the pressure or operate as leaf valves.

An embodiment of the present invention will be described below based on the illustrated embodiment. In the figure, number 1 indicates a welding electrode of a spot welding machine, etc., and this welding electrode 1 is connected to a diaphragm cylinder 3 via a piston cylinder 2. It is connected to the diaphragm 4.

In the diaphragm cylinder, an electrode pressure side impulse line 5 communicates with the upper chamber 4a of the diaphragm 4, and an electrode rising side impulse line 6 communicates with the lower chamber 4b of the diaphragm 4, respectively.

The electrode pressurizing side pressure conduit 6 has a valve 8 for opening/closing the conduit, a filter 9, a high pressure reducing valve 10, and a two-way electromagnetic valve from the air pressure source 7 side through which the proximal end passes toward the diaphragm cylinder 3. A switching valve 11 and a flow rate control valve 12 are each incorporated.

The flow rate control valve 12 includes a throttle valve section 12a and a throttle valve section 12a.
The check valve 12b is built into a bypass passage 5a that detours around the diaphragm upper chamber 4a and is opened by air pressure from the diaphragm upper chamber 4a.

On the other hand, the electrode rising side impulse line 6 is a branched part between the filter 9 and the high pressure reducing valve 10 in the electrode pressurizing side impulse line 5, and the low pressure reducing valve 13, a two-way electromagnetic switching valve 14, and a quick exhaust valve 15, respectively.

This quick exhaust valve 15 is a check valve 1 of the flow rate control valve 12.
The welding electrode 1 has a check valve 15a facing oppositely to the welding electrode 2b.
It is configured to perform a relief valve function when lowering.

Next, the operation of the above embodiment will be explained.

When performing spot welding with the welding electrode 1 locked in the raised position, each 20,000-way electromagnetic switching valve 11,
14, the pressure side 20,000-way electromagnetic switching valve 11 is switched to a position where the diaphragm side pipe line and the air pressure source side pipe line communicate with each other, and the rising side two-way electromagnetic switching valve 14 is switched to the low pressure side. The pressure reducing valve 13 and the rapid exhaust valve 15 are switched to the blocking position.

When the valve 8 is opened from this state, the air pressure from the air pressure source 7 is applied to the diaphragm through the filter 9, the high pressure reducing valve 10, the 20,000-way dew flow switching valve 11, and the throttle valve part 12a of the flow rate control valve 12. Flowing into the upper chamber 4a, the diaphragm upper chamber 4a is gradually expanded, and the rapid exhaust valve 15 operates as a relief valve.
The pressure in the lower diaphragm chamber 4b is gradually reduced as the pressure in the upper diaphragm chamber 4a increases, so that the welding electrode 1 gradually descends and pressurizes a workpiece (not shown) to be welded.

After welding is completed, each two-way electromagnetic switching valve 11, 1
4 to the illustrated position, the air pressure from the air pressure source 7 passes through the electrode rising side impulse pipe 6 and reaches the diaphragm lower chamber 4.
As the pressure inside the diaphragm lower chamber 4b increases, the welding electrode 1 rises to the standby position, and is locked by switching the 20,000-way electromagnetic switching valve 14 at the rising standby position. Retained.

As described above, this invention provides a diaphragm cylinder for raising and lowering a welding electrode, in which a flow velocity control valve having a function of throttling supply air pressure is provided on the electrode pressurizing side impulse pipe communicating with the upper chamber of the diaphragm, and on the electrode rising side communicating with the lower chamber of the diaphragm. The impulse pipe is equipped with a rapid exhaust valve that gradually depressurizes the lower diaphragm chamber when supplying pressure to the upper diaphragm chamber and operates as a leaf valve.
．． As is clear from the comparison with the figure, unlike the conventional case where the welding electrode is lowered by its own weight, the welding electrode can be lowered gradually and gently by the IJ leaf function of the rapid exhaust valve. Therefore, there is no danger that the workpiece will be dented or the welding electrode will be damaged due to the impact caused by the descending welding electrode, and variations in welding conditions can be prevented.

In addition, with this invention, the back pressure in the lower chamber of the diaphragm can be smoothly removed using the rapid exhaust valve, allowing the welding electrode to be further lowered, thereby increasing the rate of rise in hoe pressure. It has many beneficial effects, such as improving welding results.

[Brief explanation of the drawing]

Fig. 1 is a welding electrode pressurization raising/lowering control circuit diagram showing an embodiment of the present invention, Fig. 2 is a graph showing a welding electrode pressurizing force control mode using a two-stage pressurization method, and Fig. 3 is a diagram of the present invention. It is a graph showing the pressurization control mode of the welding electrode by the device. 1...Welding electrode, 2...Piston cylinder, 3...Diaphragm cylinder, 4a...Diaphragm upper chamber, 4b...Diaphragm lower chamber, 5...
Electrode pressure side impulse pipe, 6... Electrode rising side pressure impulse pipe, 12
...Flow rate control valve, 15... Rapid exhaust valve. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 It has a diaphragm cylinder that moves in a short stroke range necessary for welding pressurization, and a piston cylinder that moves the entire cylinder up and down in a long stroke range necessary for welding operation, and has an upper chamber and a lower chamber of the diaphragm cylinder. In a resistance welding machine that controls the pressurizing force of the welding electrode by supplying air with a pressure difference between the diaphragm cylinder and the diaphragm, a flow rate control valve having a supply pressure throttling function is installed in the electrode pressure side impulse pipe that communicates with the diaphragm upper chamber of the diaphragm cylinder. The welding electrode is pressurized by a rapid exhaust valve that operates as a relief valve to gradually reduce the pressure in the diaphragm lower chamber when pressure is supplied to the diaphragm upper chamber. Device.