JPS582742B2 - Chiyokuryua - Kuyosetsukino Seigiyosouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a DC arc welding machine having a welding current self-holding function.

In a DC arc welding machine used for semi-automatic arc welding, etc., when the operating lever of the welding torch is pressed, the torch switch closes and sends a start signal to the welding machine control section.This signal turns on the welding power, cuts the welding wire, Various operations necessary to start welding, such as supplying shielding gas, are performed.

However, when welding takes a long time, it is a burden on the operator to keep pressing the control lever, so this type of welding machine continues welding even if the control lever is released after welding has started, and the next switch operation will stop welding. Many of them have a self-holding function for the welding current to end.

The means for this are (1) one that detects the welding current and uses it as a self-holding signal, (2) one that forms a self-holding circuit regardless of the welding current through sequence control, and (3) one-time press as a torch switch. There are two types of devices: those that use a special switch that turns on when pressed, and then turns off when pressed the next time.

The problem with these conventional devices is that the means (1) uses a current transformer as shown in FIG. 3. It requires a complicated current detection device that converts it into a constant level signal with a constant voltage element 4, amplifies it with a transistor 5, and operates a relay 6, and because it uses a current transformer, the welding power source's alternating current Since the current must be detected on the side, the circuit configuration and wiring become complicated.

Measures (2) and (3) are unreasonable in that if arc breakage occurs during welding, wire feeding continues unnecessarily until the operator operates a switch to stop welding, and there are also many relays. The use of special switches also increases the cost.

In view of these drawbacks of conventional devices, the present invention provides a control device for a DC arc welding machine that is simple in structure and has a welding current self-holding function that can immediately stop wire feeding in response to arc breakage during welding. To put it simply, it is a magnetic response switch such as a reed switch that self-maintains a signal circuit for starting a welding machine in a closed state by sensing the magnetic flux generated by the welding current inside a welding torch, and its self-responsive switch. It has a built-in retention and release mechanism.

A torch switch for starting welding may be provided separately, or a magnetic response switch may also be used.

Figure 2 is a system diagram when the present invention is applied to a semi-automatic arc welding machine, where 7 is a welding power source, 8 is a welding wire feeder, and 9
is a control box, 10 is a gas cylinder, 11 is a welding torch, 12
．． 13 is a power cable, 14 and 15 are control cables, 1
Reference numeral 6 indicates a cast hose, and reference numeral 17 indicates a conduit tube with a built-in cable conductor. Various operations necessary for welding, such as turning on the welding power source and feeding the welding wire and shielding gas, are performed by a start signal sent from the welding torch to the control box 9. It will be done.

In one embodiment of the present invention, as shown in FIGS. 3 to 5, a magnetic circuit consisting of a magnetic band 20 surrounded by a conductor 18 through which welding current flows and having a gap 19 in a part is provided in the welding torch 11. A reed switch 21, which has a pair of reed pieces sealed in a glass tube, is fixed in the gap 19 by a non-magnetic material 22.

This reed switch is connected in parallel to a torch switch 24 which is opened and closed by an operating lever 23 to a welding machine starting signal circuit (see 25 in FIG. 5) which leads to the control box 9 in FIG. 1.

The magnetic flux shorting piece 26 is slidably provided with respect to the magnetic band 20 so that one end faces the cavity 19 .

This magnetic flux shorting piece is attached to a push button 27 on the side of the torch, and is normally placed in an inactive position where it escapes from the cavity 19 by a spring 28.

29 Pa operation lever return spring, 30 Pa upper parts 18-2
This is the torch grip part that stores the 9.

When the operating lever 23 is pushed in the direction of the arrow to start welding, the torch switch 24 is first closed, and the welding machine starts operating based on that signal.

When welding current flows, the magnetic flux generated around the conductor 18 concentrates on the reed switch 21 placed in the gap 19 of the magnetic band 20 of the magnetic circuit, so the reed switch 21 closes the signal circuit 25 in response to the magnetic flux. self-maintain in a state;

Therefore, even if the torch switch 24 is opened after welding has started, the self-holding function of the reed switch 21 continues the welding.

To finish welding, when another pushbutton 27 is pressed, the magnetic flux shorting piece 26 protrudes into the gap 19 of the magnetic circuit and short-circuits the magnetic flux passing through the gap 19.
The self-holding function of the welding power source is released, and by opening the signal circuit, the power supply from the welding power source, wire, and gas supply all stop.

In order to carry out the various operations at the start and end of welding described above, it is sufficient to have one relay on the receiving side that responds to the presence or absence of a start signal from the torch. No need for complex sequence circuits to determine operations.

In the other embodiments shown in FIGS. 6 and 7, the reed switch 21 is also used as a torch switch, and the explanation of the parts common to the previous embodiments will be omitted.

When the operating lever 23 is pushed in the direction of the arrow to start welding, the permanent magnet 31 attached to the operating lever 23 activates the reed switch 2 fixed in the gap of the magnetic band 20 of the magnetic circuit.
1, the magnetic flux causes the reed switch 21 to operate and close the signal circuit 25.

When the operating lever 23 is released after welding starts, the spring 29 overcomes the attractive force acting between the magnetic band 20 and the magnet 31 and returns the lever 23 to the illustrated position.

However, as described above, the reed switch 21 senses the magnetic flux generated around the conductor 18 by the welding current and self-maintains the signal cycle, thereby sustaining welding.

As in the previous embodiment, the self-holding function is released by moving the magnetic flux shorting piece 26 to the active position at the end of welding.

As explained above, according to the present invention, it is possible to obtain a control device for a DC arc welding machine having a welding current self-holding function with an extremely simple configuration compared to conventional devices, and the product price can be reduced.

Furthermore, when the present invention is applied to a semi-automatic arc welding machine,
If arc breakage occurs during welding, the self-holding of the signal circuit is released and wire feeding is immediately stopped, so the length of the wire protruding from the tip of the torch does not become too large and interfere with the next arc start.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing one row of conventional equipment, Fig. 2 is a system diagram of a semi-automatic arc welding machine to which the present invention is applied, and Fig. 3 is a vertical sectional view of essential parts showing one row of implementation of the present invention. 4 is a cross-sectional view thereof, FIG. 5 is a circuit diagram thereof, FIG. 6 is a longitudinal sectional view of a main part showing another embodiment, and FIG. 7 is a circuit diagram thereof. Explanation of symbols 11... Welding torch, 18... Conductor through which welding current flows, 20... Magnetic band, 21... Magnetic responsive switch, 24... Torch switch, 25...
-Signal circuit, 26...Magnetic flux short circuit piece, 27...Push button for operation.

Claims (1)

[Claims] 1. A magnetic circuit disposed inside the welding torch in close proximity to a conductor through which welding current flows, a magnetically responsive switch provided in this magnetic circuit and connected to a signal circuit for starting the welding machine, and this magnetically responsive switch. A control device for a DC arc welding machine, comprising a magnetic flux shorting piece that is provided in parallel with the magnetic circuit and is movable by manual operation.