JPH0231266Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an abnormality detection protection and control device for a resistance welding machine.

Previously, the present applicant proposed a resistance welding machine in which welding was performed according to a predetermined program using a control device consisting of a timer unit and a contactor.
We have proposed an abnormality detection and protection device that is installed separately from the control device to detect electrical leakage due to poor insulation of the cable that connects the power source and the welding transformer, as well as damage to the cable, and to shut off the welding power source circuit.

However, since the control device and the abnormality detection and protection device are manufactured separately, this device occupies a large space and the cost of materials such as the box is expensive.
There were disadvantages such as troublesome wiring work and maintenance/inspection work.

The purpose of the present invention is to provide a device free from such inconveniences, which includes a contactor 3 interveningly connected to a circuit connecting a power source and a welding transformer within a box 1, and a timer unit controlling the contactor 3. 2, and electric components 4 ₁ to 4 ₃ such as transformers that constitute a circuit through which an abnormal current flows when a leakage occurs in the cable connected to the core wire of the cable connecting the power source and the welding transformer. The present invention is characterized in that it is provided with an earth leakage relay 5 for detecting abnormal current in the circuit, and an earth leakage breaker 6 for interrupting the welding power supply circuit by the operation of the earth leakage relay 5.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the device A of the present invention connected to a resistance welding machine C mounted on a robot B. Device A
The cable _l1 drawn out from the upper part was connected to a welding power source (not shown), and the cable _l2 drawn out from the lower part was connected to a welding transformer D mounted on the robot B. In addition, a cable _l3 pulled out from the bottom was connected to a control power source and an operation power source (not shown).

FIG. 2 shows a connection diagram of the device of the present invention.

As shown in the figure, a circuit 7 connecting the cable l ₁ connected to the welding power source and the cable l ₂ connected to the welding transformer D is connected to a contactor 3 made of a thyristor, an earth leakage breaker 6, and an operating power source. The contact point 8a of the electromagnetic contactor 8 was inserted. The contactor 3 and the pressurizing valve of the welding machine were operated sequentially according to a program by a timer unit 2 which started operation when a start switch 9 was closed.

In the figure, reference numeral 10 denotes a circuit through which an abnormal current flows when the shield of the cable l ₁ is broken, and the circuit 10 includes a transformer 4 ₁ connected to a control power source,
It is composed of resistors 4 ₂ and 4 ₃ , etc., and both ends of the resistor 4 ₃ are connected to the shield wire W ₁ of the cable l ₂ via the terminal block 11.
and connected to ground wire _W3 . The cable _L2 consists of a pair of conductors _W2 for the welding power source, a ground conductor _W3 , a valve signal line (not shown), the shield wire _W1 surrounding these conductors, and an insulating coating on its outer periphery (Fig. (not shown).

The earth leakage relay 5 that operates the earth leakage breaker 6 is energized by the output of the zero-phase current transformer 12 inserted in the circuit 10.

13 is a programmer.

FIGS. 3A and 3B show a front view and a side view of the present device.

In the figure, reference numeral 1 denotes a box that houses each part of the device, the front of the box 1 is a door ₁₁ that can be opened and closed with a handle 14, and the upper, lower, and rear surfaces on the right side are formed by punched perforated plates. The contactor 3 and the resistors 4 ₂ , 4 ₃ , and 24 made of a thyristor attached to the board are air-cooled.

The timer unit 2 was attached to the door ₁₁ , and the power transformers 15 and 16 of the timer unit 2 were attached to the top of a board fixed to the bottom of the box 1.

An electromagnetic contactor 8 in which an earth leakage breaker 6, an earth leakage relay 5, resistors 4 ₂ , 4 ₃ and a transformer 4 ₁ constituting the circuit 10, and a zero-phase current transformer 12 are attached from the top to the center of the board. was attached to the lower part of the earth leakage breaker 6.

A programmer 13 was attached to the upper part of the door body ₁₁ so as to be exposed on the surface, and the programmer 13 was covered with a transparent cover 17. The above electric devices and parts were connected to each other according to the connection diagram shown in the second figure.

In FIGS. 2 and 3, 18 is a current transformer;
9 is a timer unit abnormal signal output relay, 2
0 and 21 are pilot lamps PL ₁ and PL ₂ , respectively.
11 and 22 are terminal blocks, 23 is a grounding resistance of a welding transformer 24, 24 and 25 are resistors, and 26 is a capacitor.

In FIG. 3, the cables l ₁ , l ₂ , and l ₃ are omitted.
Thus, when the device is connected to the welding power source and the operating power source via the cables l ₁ and l ₃ , the electromagnetic contactor 8 is activated and its contacts 8a are closed. Ground leakage circuit breaker (NFB)
When 6 is turned on, the pilot lamps PL ₁ , 20 and
PL ₂ 21 lights up. When the start switch 9 is closed, the timer unit 2 is activated by the programmer 13.
It operates according to the instructions given, and predetermined welding work is performed in sequence.

When the cable _L2 is damaged and its shield wire _W1 is connected to the conductor _W2 for the welding power source or the workpiece, an abnormal current flows through the circuit 10, and the earth leakage breaker is activated by the earth leakage relay 5, and the welding power source is disconnected. The circuit is opened. Also, when the contactor, which is a thyristor, malfunctions and short-circuits, the earth leakage breaker is activated and the circuit is opened.

In this way, according to the present invention, inside the box body 1,
A contactor 3 that is interveningly connected to the circuit connecting the power source and the welding transformer and a timer unit 2 that controls the contactor 3 are provided, and a timer unit 2 that is connected to the conductor of the cable that connects the power source and the welding transformer is installed to prevent leakage of the cable. Electrical components such as transformers that make up the circuit through which abnormal current flows when an abnormality occurs 4 ₁ ~
4 ₃ , an earth leakage relay 5 that detects abnormal current in the circuit, and an earth leakage breaker 6 that cuts off the welding power supply circuit by the operation of the earth leakage relay 5, so it is easy to control the resistance welding machine and prevent cable leakage. The device for detecting and protecting an abnormality occupies a small space, the cost of materials is low, and wiring work and maintenance and inspection work are easy.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a resistance welding device using the device of the present invention, FIG. 2 is a connection diagram of the device of the present invention, and FIGS. 3A and 3B are front and side views of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Box, 2...Timer unit, 3...Contactor, _41-43 ...Electrical components, ₅ ...Earth leakage relay, 6...Earth leakage breaker.

Claims (1)

[Scope of utility model registration request] A contactor 3 which is interveningly connected to the circuit connecting the power source and the welding transformer and a timer unit 2 which controls the contactor 3 are arranged in the box body 1, and a core wire of the cable connecting the power source and the welding transformer is provided. Electrical parts 4 ₁ to 4 ₃ such as transformers that are connected and constitute a circuit through which an abnormal current flows when a leakage occurs in the cable, an earth leakage relay 5 that detects the abnormal current in the circuit, and the operation of the earth leakage relay 5. An abnormality detection protection and control device for a resistance welding machine, characterized in that an earth leakage breaker 6 is provided to interrupt a welding power supply circuit.