JPH0284276A - Electrode pressure device for resistance welding machine - Google Patents

Abstract

PURPOSE:To measure the pressing force in the course of electric conduction by connecting a piston rod and a ram so as to be floatable through an elastic member, and detecting the displacement quantity by a sensor provided on a ram hollow part, at the time of pressing an electrode. CONSTITUTION:In a state that the title device is opened by pressure, a clearance I0 between the lower-end face of a through-hole 4b and a washer 5' is zero by raising force of a spring S. A detection use operating rod 11a of a differential transformer 11b of a sensor is always pushed up by an auxiliary spring 11c. A distance L0 extending from the upper face of a body of the differential transformer 11b to the lower end face of a piston rod 3c corresponds to zero of pressing force. In case of a pressure state, I0 becomes I1, and L0 is varied to L1. A stroke variation of the detection use operating rod 11a of the differential transformer is fetched as a pressure signal. In an electric conduction period of a welding process, electrode pressing force is measured, and the setting accuracy of press-contacting force can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrode pressurizing device for measuring electrode pressurizing force of a stationary resistance welding machine.

(Conventional technology) The pressure welding force in resistance welding is determined by the mechanical operation (
The time it takes to reach the appropriate pressure varies depending on the welding machine (friction system), etc.

For example, if the rise time of the electrode pressure, ie, the squeeze time, becomes longer, not only will the welding takt become longer, but also welding defects will occur, which can readily respond to the expansion of the weld nugget during welding.

Furthermore, if the squeeze time is short, the pressurizing force will be insufficient, causing spatter or explosions during welding, which will adversely affect the welding results.

Conventionally, the method for measuring the electrode pressure required for stationary resistance welding machines is to insert a pressure gauge between the upper and lower electrodes with the welding current cut off, and then use mechanical action to sandwich it between the electrodes and measure the pressure. It was common practice to measure only the static contact force generated in the meter with a dial gauge, and to set the pressure force setting and time setting respectively to pressurizing equipment, timer equipment, etc.

In order to obtain a welding joint with high welding strength in resistance welding, it is desirable to start applying welding current after the pressure contact force on the welding area has risen to the planned pressure, and also to prevent the welding area from heating and softening. It is said that it is desirable to release the electrode pressure after the temperature of the welded part has dropped to an appropriate temperature.

(Problems to be Solved by the Invention) The method using the pressure needle described above cannot accurately measure the electrode pressure in conjunction with the timing of the welding current.
Most of the conditions for the equipment described had to be determined by the intuition of the operator based on empirical rules.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pressurizing device for a resistance welding machine that is useful when measuring pressure contact force in conjunction with the timing of application of welding current.

(Means for Solving the Problems) In order to achieve the above object, the present invention fixes a ram guide to the upper arm of a resistance welding machine, provides a pressurizing cylinder in which a piston rod is inserted into the ram guide, and The rod and the ram inserted in the ram guide are connected so that they can float via an elastic member, and a sensor installed in the hollow part of the ram measures the amount of displacement that occurs between the piston rod and the ram when the electrode is pressurized. We have taken technical measures to detect it.

(Function) In the present invention, when the pressure of the pressurizing cylinder is applied to the piston rod during electrode pressurization, since the piston rod and the ram are connected via an elastic member such as a spring, the spring constant of the spring increases. In relation to this, the spring creates a certain flexure platform and balances, applying pressure to the ram.

The amount of deflection of the spring is proportional to the applied pressure, so by detecting the spring's peak iL with a sensor, the pressure contact force when applying electrode pressure can be accurately measured, and the amount of deflection of the spring can be measured during welding. In addition to pressure, it also reflects the amount of thermal expansion during weld nugget formation.

Therefore, in the welding process of resistance welding, it is possible to measure the electrode pressing force during the welding nugget generation process even while the welding current is being applied, or to monitor the amount of thermal expansion during the welding nugget generation process, as well as to monitor the squeeze time, etc. The time can be set according to the optimal welding conditions. Therefore, it is possible to further shorten the time of the welding process, and it is possible to improve the accuracy of setting the pressure welding force to obtain optimal welding quality.

(Embodiments) Hereinafter, preferred embodiments of the apparatus of the present invention will be described with reference to the attached drawings.

Note that FIG. 1 is a sectional view of a main part showing a configuration example of the device of the present invention, and FIG. 2 is a sectional view of a main part of the device of the present invention during an opening operation. Further, FIG. 3 is a sectional view of a main part of the apparatus of the present invention during pressurizing operation.

In the figure, 1 is the upper arm of a stationary resistance welding machine, 2 is a ram guide fixed to the tip of the upper arm 1, 3 is a pressure cylinder fixed to the upper end of the ram guide, and the piston rod 3
C is inserted into the hollow part of the ram guide 2 and can move integrally with the piston 3b sliding on the cylinder case 3a.

A ram 4 is inserted from below the ram guide 2 and slides on the inner wall of the ram guide. The connecting portion between the ram 4 and the piston rod 3C is, for example, inserted into the outer periphery of the reduced diameter tip 3d of the piston rod so as to surround a washer 5 and an elastic member such as a spring S, as shown in the figure. is inserted into a through hole 4b provided in the upper partition wall 4a of the ram 4, and a washer 5' nut N is inserted around the outer periphery of the inserted tip and tightened with a screw. Reference numeral 7 denotes an electrode support arm fixed to the lower end of the ram, and an electrode tip 6 is attached to the tip thereof. A lower arm 8 corresponds to the upper arm, and supports an electrode tip 9 corresponding to the electrode tip 6 via an electrode support arm 10.

A sensor 11 is fixed to a lower partition wall 4c located on the same axis as the piston rod 3c and directly below the piston rod 3c which is connected to the upper partition wall 4a of the ram 4. This sensor 11 has an operating rod l for detection.
It consists of a differential transformer Ilb in which la is always in contact with the lower surface of the piston rod 3c by an auxiliary spring IIC.

The operation of the apparatus of the present invention having such a configuration will be explained below.

FIG. 2 shows the device of the present invention in a pressurized and released state.

In this case, the piston rod 3c and the ram 4 are connected to the spring S
Since the ram 4 is attached so as to be floating via the ram 4, the gap 10 between the lower end surface of the through hole 4b of the ram 4 and the washer 5' that fastens the piston rod 3c to the ram 4 with a nut N is zero. In other words, when the pressure is released, the spring S
The deflection of the sensor is zero, and the detection operating rod 11a of the differential transformer of the sensor is always pushed upward by the auxiliary spring llc.

Piston rod 3c from the top surface of the main body of differential transformer llb
The distance L0 from the lower end surface of indicates the amount of displacement when the pressure is released, and is the displacement measurement in this case. corresponds to zero pressing force.

Next, FIG. 3 shows a state in which the apparatus of the present invention is pressurized. In this case, the balance between the spring constant of the spring S and the cylinder pressure applied to the piston rod 3c causes a deflection it ll to apply pressure to the ram 4, and the displacement between c and d of the differential transformer Ilb changes. do. That is, Ll
>L (indicates the relationship of 1.

(') If the stroke change of the detection operating rod Ila of the differential transformer is electrically processed, it will appear as a stroke change of the differential transformer depending on the magnitude of the pressurizing force, and this can be extracted as a pressurizing force signal. , the true pressing force can be measured.

In this embodiment, a differential transformer is used as a sensor for detecting the amount of deflection of the spring, but it goes without saying that other eddy current type non-contact sensors can also achieve the same effect.

(Effects of the Invention) As explained above, according to the device of the present invention, in the pressurizing device of a stationary resistance welding machine, the piston rod of the pressurizing cylinder and the ram inserted in the ram guide are connected via the spring. Since the screws are slidably connected and a sensor installed on the axis of the piston rod in the ram hollow part detects the amount of deflection of the screws that occur when the electrodes are pressurized, it is no longer the same as before. There is no need to measure the electrode pressing force separately from that between the welding energizers, and it is possible to measure the electrode pressing force at the same time during the energization period in the normal welding process.In addition, the spring deflection iL can be measured during welding. The amount of thermal expansion during weld nugget formation is also shown.

That is, the device of the present invention measures the electrode pressing force during the welding nugget generation process during the welding current opening period in the welding process of resistance welding, or measures the change in the electrode pressing force depending on the amount of thermal expansion during welding nugget generation. In addition to being able to monitor the welding process, it is also possible to set the squeeze time and other settings to match the optimal welding conditions, making it possible to further reduce the time required for the welding process. By taking advantage of these effects, it is possible to improve the setting accuracy of the pressure welding force to obtain optimal welding quality, and welding quality control becomes much easier.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts showing an example of the configuration of the device of the present invention. Second
The figure is a sectional view of the main part of the device of the present invention when the pressurizing operation is released. FIG. 3 is a sectional view of the main part of the apparatus of the present invention when pressurized. [Explanation of symbols] 1... Upper arm, 2... Ram guide, 3... Pressure cylinder, 3c... Piston rod, 4... Ram, 11... Sensor, S... Elastic member (spring) Grinding patent applicant Dengensha Manufacturing Co., Ltd.

Claims (1)

[Claims] A ram guide is fixed to the upper arm of a resistance welding machine, a pressurizing cylinder is provided with a piston rod inserted into the ram guide, and the piston rod and the ram inserted into the ram guide are made floating via an elastic member. An electrode pressurizing device for a resistance welding machine, the electrode pressurizing device for a resistance welding machine being connected to the ram and detecting the amount of displacement generated between the piston rod and the ram when the electrode is pressurized by a sensor provided in a hollow part of the ram.