JPH0120954B2 - - Google Patents

Description

Detailed Description of the Invention Arc welding using a consumable wire electrode (hereinafter simply referred to as wire) is a method in which, for example, a supplied wire passes through a current-carrying tip provided at the tip of a welding torch, and the current is applied by this current-carrying tip. Automatic or semi-automatic arc welding using a wire in which a welding arc is ignited between the base metal and the base metal, or by igniting the welding arc between a non-consumable electrode such as tungsten and the base metal. This is an automatic or semi-automatic arc welding method in which a wire (generally referred to as filler wire) is fed into the welding arc, and a small current sufficient to preheat the wire is passed through the wire (generally referred to as hot wire). . The wire is let out from the wire reel by a wire feeding device, passes through a wire feeding tube (conduit tube), and reaches the tip of the torch.

In conventional semi-automatic arc welding machines, operating the torch switch simultaneously feeds the wire from the wire reel to the tip of the torch, outputs the welding power output, and supplies shielding gas. Ta. Therefore, at the start of welding, when the wire is fed from the reel through the conduit tube to the tip of the torch and is made to protrude from the tip of the torch by an appropriate length (this operation is called inching), the signal 1 from the torch switch is sent as shown in Figure 1. While it is ON (H level), output voltage 2 is supplied, the wire feed motor rotates 4, and the solenoid valve for shielding gas supply opens 5. If the wire protrudes too far from the tip of the torch and touches the base material, There have been cases where sparks are emitted, causing damage to the welded workpiece, or the welding object is easily shaken during work, increasing the risk of electric shock or wasting shielding gas. At this time, no welding arc is generated, so the output current 3 is not supplied. The symbols in Figure 1 indicate the respective operating signals; ON (operation) at H level and OFF (stop) at L level.
shows. Therefore, a method of separately installing a wire inching switch that has the function of starting and stopping only the wire feeding is generally adopted, but for remote control, the circuit is complicated, such as requiring an extra extension control line. It happened that it became.

The object of the present invention is to eliminate the above-mentioned conventional drawbacks and to provide an easy-to-operate, safe and economical arc welding method.

In order to achieve the above object, the present invention provides that if no welding arc is generated even after a predetermined period of time has elapsed since the torch switch was operated, the wire feed motor continues to rotate, but the output voltage and shielding gas are stopped being supplied. It is characterized by causing

An embodiment of the present invention will be described in detail below with reference to the drawings. 2 and 3 are circuit diagrams showing one embodiment of the present invention, and FIG. 4 is a time chart for explaining the operation of FIGS. 2 and 3. In FIG. 2, 1 is a welding transformer, and 2 is an output power supply circuit, which is specifically composed of control elements such as transistors or thyristors. A consumable wire electrode 3 is drawn out from the wire reel 4 and fed toward the base material 6 by a feeding roll 5. 7 is the feed roll 5
The feed motor rotates the motor, and its rotation and stop are controlled by a motor drive circuit 8.
Reference numeral 9 denotes an output control circuit of the output power supply circuit 2, which is connected to the output power supply circuit 2 via a disconnection circuit 10. For example, when the elements constituting the output power supply circuit 2 are thyristors, the output control circuit 9 is an ignition control circuit. 1
Reference numeral 1 denotes a current detection circuit, which is inserted between the output power supply circuit 2 and the current-carrying terminal 12. Figure 3 shows a sequence circuit that controls the operation order in Figure 2, with relays 13,
14 and their normally open contacts 13a, 14a, solenoid valve 15, torch switch 16, current detection circuit 11
It is composed of a normally open contact 11a, a line connecting these contacts, and a sequence power supply (not shown).
A timer 13 is connected to a torch switch 16, and a relay 14 is connected in parallel to this timer 13.
The solenoid valve 15 has a normally open contact 14a and a timer contact 13a.
The contact 11a is connected in series with the timer contact 13a.
are connected in parallel. The timer contact 13a, the relay contact 14a, and the current detection contact 11a are connected to the switching circuit 10.
Configure. Further, the relay contact 14a is connected to an input terminal for controlling ON/OFF of the motor drive circuit 8.

Next, the operation will be explained using FIG. 4. When the torch switch 16 is set to ON state 1 by an operator's operation or another sequence control signal (such as a welding start signal in an automatic welding machine), its contacts close, the timer 13 and the relay 14 are energized, and their normally open contacts 13a and 14a are turned on. close. Therefore, solenoid valve 1
5 is activated, and shielding gas is supplied to the torch through a gas passage (not shown). The motor drive circuit 8 is actuated by the contact 14a, the feed motor 7 starts feeding the wire 3 via the feed roll 5, and the contacts 13a and 14a are closed, so that the output power circuit 2 is connected to the output control circuit 9. A control signal is applied, and a welding voltage 2 is supplied to the wire 3. The contact 14a remains closed until the contact of the torch switch 16 opens, but the timer contact 13a remains closed for a predetermined period of time (approximately 1
It will open after ~2 seconds). The current contact 11a is closed by a signal (current is present) from the current detection circuit 11, and remains closed when there is no current. Since the timer contact 13a and the current contact 11a are connected in parallel, if an arc is ignited between the wire 3 and the base metal 6 within the predetermined time set in the timer 13 after turning on the torch switch 16, Since the contact 11a is closed by the signal from the current detection circuit 11, welding can proceed, but timer 1
If the arc is not ignited within the specified time set in 3, the welding current will not flow, so
Output 3 from 1 maintains the L level state. Therefore, if an arc does not occur within a predetermined time, the solenoid valve 15 is demagnetized 5 and the supply of shielding gas is stopped, and similarly, the output signal from the output control circuit 9 cannot be applied to the output power supply circuit 2. Output voltage 2 is stopped. Since the wire motor 7 continues to rotate until the torch switch 16 is operated and its contacts open, the wire 3 is fed.

FIG. 5 is a flowchart showing the above operation. A description of the case where the present invention is implemented using a microcomputer, which has been put into practical use in recent years, will be omitted, but it goes without saying that the present invention can be implemented using a flowchart such as the one shown in this figure.

As described above, the present invention is capable of stopping the output voltage solenoid valve and feeding only the wire until the torch switch is opened when no arc is generated even after a certain period of time after starting the torch switch that starts and stops the arc. This unique welding machine control method stops energizing the wire in a short period of time (1 to 2 seconds) during wire inching operations such as when starting welding, so there is no spark even if the wire comes into contact with the base metal. This improves work efficiency and safety, as there is no risk of electric shock even if the product swings at the worker. Furthermore, it is economical because wasteful discharge of shielding gas is eliminated.
Further, since no other switch is required for wire inching, the structure of the welding machine can be simplified, and since the torch switch and inching switch can be used together, operability is improved.

[Brief explanation of drawings]

FIG. 1 is a time chart of a conventional welding method. 2 and 3 are circuit configuration diagrams showing one embodiment of the present invention, FIG. 4 is a time chart explaining the operation of the present invention, and FIG. 5 is a flow chart. 2...Output power supply circuit, 3...Wire, 5...Feeding roll, 6...Base material, 7...Wire feeding motor, 8...Motor drive circuit, 9...Output control circuit, 10...Switching circuit, 11...Current detection circuit , 13...timer, 14...
Relay, 15...Solenoid valve, 16...Torch switch.

Claims (1)

[Claims] 1 In the arc welding method performed by feeding a welding wire electrode, the output voltage and shielding gas from the wire electrode and welding power source are supplied to the tip of the torch by operating a torch switch, and after a predetermined period of time, the welding arc is ignited. An arc welding machine control method characterized by stopping the supply of output voltage and shielding gas when detecting no arc, and feeding only the wire electrode until the next time the torch switch is operated.