JPS6254585B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a short-circuit transitional arc welding machine, which detects a short-circuit in a wire electrode and arc regeneration to control the current supplied from the welding machine.

FIG. 1 is a diagram showing the configuration of a short-circuit transition type arc welding machine according to the prior art, in which 1 is a DC power supply circuit that receives AC power as input, 3 is a pulse waveform setting circuit that sends out a pulse current value command signal a, and 14 is a pulse cycle setting circuit that sends a pulse current cycle command signal b;
12 is a switch command circuit that receives the pulse current value command signal a and periodic command signal b of these setting circuits 13 and 14 and controls the ON-OFF cycle of the switching element 2 such as a transistor; 3 is a DC reactor;
4 is a flywheel diode for preventing the reverse voltage (high voltage) from the DC reactor 3 from being applied to the switching element 2 immediately after the switching element 2 is turned off; 5 is a DC current for maintaining the welding arc (hereinafter referred to as 6 is a reel of welding wire, 7 is welding wire, 8 is a motor that feeds wire 7, 9 is a welding torch, 10 is the base material, 11 is welding Current detector whose output is switch command circuit 1
2 and compared with the pulse current value command signal a, and controls the ON/OFF timing of the switching element 2 so that a pulse current of a predetermined value is obtained.

Next, the operation when short-circuit transition welding is performed using the welding machine configured as described above will be explained.

The synchronization command signal b and the pulse current command signal a selected for the selected wire feeding speed in advance are led to the switch command circuit 12, and the ON-OFF command signal is inputted from this command circuit 12 to the switching element 2. A pulse current of a constant value is made to flow with a constant pulse period T.

Next, welding is started by bringing the tip of the wire electrode 7a into contact with the base material 10, and the first pulse current burns out the short-circuited wire electrode 7a and generates an arc. Subsequently, this arc heats and melts the tip of the wire electrode 7a and the base material 10, and the welding wire 7 is fed in, and the molten wire electrode 7a is pressed against the base material 10, and the wire electrode is short-circuited by the next pulse current. 7a
Welding is performed by repeatedly burning out the arc and then generating the arc again.

However, in this device, the feeding speed of the wire electrode and the generation cycle of the pulse current were set separately and were not related to each other, so the timing at which the molten wire tip was pressed against the base material and the timing at which the pulse current was applied were synchronized. For this reason,
The wire electrode sometimes sticks into the base metal for a long period of time, and many large spatters are scattered and the spatters adhere to the base metal or accessories such as the welding machine.

Furthermore, if the timing between the arc regeneration and the end of the pulse is greatly different, the arc length will be different, making it impossible to perform stable welding.

This invention was made in order to eliminate the above-mentioned drawbacks, and a sensor for detecting the voltage between the base material and the wire electrode is provided to detect the voltage between the base material and the wire electrode, and this voltage value is By controlling the switching element 2 to start energization when the voltage corresponding to a short circuit is reached and to end energization when the voltage corresponding to arc regeneration is reached, stable and high-quality welding with less spatter can be achieved. It was designed so that

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, 15 is a voltage detector that detects the voltage V between the wire electrode 7a and the base material 10, and 16 is the voltage V detected by the voltage detector 15 and the voltage Vo corresponding to a short circuit (the voltage at the time of a short circuit or the short circuit voltage). When V≦Vo, the switching element 2 is connected to the switch command circuit 12.
A first determiner 17 that determines a short-circuit condition that gives a command signal to be turned ON compares the voltage V detected by the voltage detector 15 with the voltage Va corresponding to arc regeneration, and determines that V≧Va. Summer timer 1
8, and after a certain period of time T, switch command circuit 1 is activated.
3A is a voltage waveform diagram of this welding machine, and FIG. 3B is a current waveform diagram.

Next, the operation of this embodiment will be explained. First, the input switches (not shown) of the DC power supply circuit 1 and the auxiliary power supply 5 are turned on, and the tip of the wire electrode 7a is short-circuited to the base material 10. Since the detected voltage V of the voltage detector 15 is smaller than the voltage Vo corresponding to a short circuit (V≦Vo), the first judge 16 operates, and an ON command signal is sent to the switch command circuit 12, followed by a switch command. A trigger signal is sent from the circuit 12, the switching element 2 is closed, and current is applied from the circuit 12. This current flows until the wire electrode 7a burns out and an arc is generated, and the detected voltage V of the voltage detector 15 increases from the short circuit voltage to the arc voltage. Then, the operation of the first judge 16 is stopped, and when the detected voltage V becomes larger than the voltage Va corresponding to arc regeneration (V≧Va), the second judge 17 is activated, the timer 18 is activated, and a predetermined value is set. After the delay time T has elapsed, an OFF command signal is sent to the switch command circuit 12, the trigger signal from the switch command circuit is cut off, the switching element 2 is opened, the current is attenuated by the reactor 3, and the auxiliary power supply 5 Only the current supplied from

In this way, the wire electrode and base metal are heated and melted during the first arc period B, and
The welding wire 7 is fed to the torch 9 by the feed motor 8, and the molten wire tip 7a short-circuits to the base metal, and the switching element 2 is closed again, and current is supplied from the DC power source to the base metal of the molten wire electrode. migration is completed. By repeating such operations, welding voltage and current waveforms as shown in FIGS. 3a and 3b are obtained, and a stable welding state is maintained.

Further, the fixed time T in the timer 18 is controlled according to the wire feeding motor 8, and the voltage detection voltage V
By converting the voltage using the average voltage converter 19 and feeding back the output to the timer 18 to adjust the delay time T to an optimal value, the average arc length due to hand shake etc. can be reduced within the entire welding current range. Fluctuations are reduced and a more stable welding condition can be obtained.

This invention is configured to apply a voltage between a wire electrode fed toward a base material and the base material, and repeat short circuit and arc discharge between the base material and the wire electrode to perform welding. A voltage detector detects the voltage between the wire electrode and the base metal, and a pulse current is passed between the wire electrode and the base metal when the detected voltage of this detector reaches a voltage value equivalent to a short circuit. and means for terminating the application of the pulsed current when the detector of the voltage detector detects the arc discharge regeneration voltage or after a predetermined delay time from that time. As a result, there are very few spatters that occur during short-circuit transition, and the spatters are also very small, so there is no adhesion of spatters to the base material, etc., which has the effect of increasing work efficiency.

In addition, since the timing of arc regeneration and the end of the pulse can be controlled, the arc length etc. during arc regeneration can be kept stable. Even when there are fluctuations in welding, such as welding, the pulse end point can be controlled in accordance with the fluctuations, which has the effect of providing versatility.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a short-circuit transitional arc welding machine according to the prior art, FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, and FIGS. 3a and 3b are voltage and current in this embodiment, respectively. FIG. In the figure, 1 is a DC power supply circuit, 2 is a switching element, 3 is a DC reactor, 4 is a flywheel diode, 5 is an auxiliary power supply, 6 is a welding wire reel, 7 is a welding wire, 7a is a wire electrode, 8
is a motor, 9 is a torch, 10 is a base material, 12 is a switch command circuit, 15 is a voltage detector, 16 is a first judge, 17 is a second judge, 18 is a timer,
19 is an average voltage converter. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Welding by applying a voltage between a wire electrode fed toward a base metal and the base metal, and repeating short circuit and arc discharge between the base metal and the wire electrode. In the device configured to A means for starting the application of the pulsed current, and a means for terminating the application of the pulsed current when the detector of the voltage detector detects the arc discharge regeneration voltage or after a predetermined delay time from that time. A short-circuit transition arc welding machine featuring: 2. The short-circuit transitional arc welding machine according to claim 1, further comprising means for controlling the length of the delay time according to the wire feeding speed and the average welding voltage.