JPH01104474A - Power unit for pulse arc welding - Google Patents

Abstract

PURPOSE:To stabilize an arc state by providing a timer circuit connected to an electric current detector and a voltage detector and increasing a pulse peak current set value when a detected voltage value decreases for a prescribed time. CONSTITUTION:The voltage detector 9 to detect the output terminal voltage is provided and the timer circuit 10 connected to the current detector 5 and the voltage detector 9 is arranged. Further, a pulse peak current rising command circuit 11 connected to the timer circuit 10 is provided. The detectors 9 and 5 detect, the arc voltage and an output current respectively and the timer 10 monitors a voltage signal of the detector 9 and when the voltage value continues to decrease exceeding the set time, the command circuit 11 actuates a switching element 4 to increase the pulse peak current set value. Since the satisfactory arc start is secured and an influence by the disturbance is prevented, the arc state is stabilized.

Description

[Detailed description of the invention] [Industrial usage IF] The present invention relates to a power supply device used for gas shield pulse arc welding using a consumable electrode in an inert gas such as argon or a mixture of oxygen, carbon dioxide, etc. with the inert gas. [Conventional technology]

Generally, in this type of welding method, the phenomenon in which the welding wire melts and transfers to the base metal changes discontinuously at a critical current value. Therefore, in order to stably spray transfer weld a base material having a relatively thin plate thickness, a method in which a pulse current is superimposed on a direct current is generally used. Tip 9: By setting the base current below the critical current and making the pulse peak current above the critical current, droplet transfer becomes spray transfer, and the average current is kept low to reduce the amount of heat input to the base material, making it relatively thin. This allows for good welding even with thick base materials. The basic configuration of the conventional pulse arc welding power supply device is
As shown in the figure. In FIG. 2, 1 is an input terminal, 2 is a transformer, 3 is a rectifier, 4 is a switching element, 5 is a current detector, 6 is a pulse peak current setting circuit, 7 is a drive circuit, and 8 is an output terminal. Next, the circuit operation will be briefly explained. The AC power inputted from the input terminal 1 is transformed into an appropriate voltage by the transformer 2, converted to DC through the rectifier 3, and then controlled to a desired current value by the switching element 4 and output from the output terminal 8. Provides power to the arc load. The output current is detected by a current detector 5,
The pulse current is input to a pulse peak current setting circuit 6, where it is compared with a preset peak current value, and an on/off signal is output depending on the polarity of the difference. The drive circuit 6 receives the signal and controls the switching element 4 to be turned on or off. In this way, the pulse peak current value of the output current is controlled to be constant.

[Problems to be solved by the invention]

However, in conventional pulsed arc welding power supplies, the pulse peak current value is fixed at a constant value that satisfies the transfer of one droplet per pulse during stable welding. Therefore, a peak current exceeding a predetermined peak current value will not flow during welding. Therefore, with conventional pulsed arc welding power supplies, if wires made of materials with higher conductivity than iron or stainless steel, such as aluminum wire or copper alloy wire for MIG brazing, are used, arc starting may not be possible. Or the arc length may be short due to disturbance during welding (
(for example, when the wire protrusion length becomes short), or in more extreme cases, when there is a short circuit with the base metal, sufficient Joule heat is not given to the wire to transition to the arc again, resulting in a welding defect. This caused problems such as causing problems. In addition, as a means to solve the above-mentioned problems, as seen in Japanese Patent Application No. 183002/1982, the wire feeding speed is reduced when a short circuit occurs between the consumable electrode and the base metal during welding. There is a method, but it is not a fundamental solution. This invention was made in order to improve these problems, and it is possible to obtain a good arc start even when performing pulse arc welding using a wire with relatively high conductivity such as aluminum, and to avoid disturbances. Another object of the present invention is to provide a power supply device for pulsed arc welding that can stably maintain the arc and perform good welding.

[Means to solve the problem]

The pulsed arc welding power source according to the present invention includes a current detector provided in an output current path, a timer circuit connected to the current detector and the voltage detector, and a pulse peak current increaser connected to the timer circuit. a command circuit, a pulse peak current setting circuit connected to the pulse peak current increase command circuit for setting the peak value of the output current, and a pulse peak current setting circuit connected to the current detector and the pulse peak current setting circuit for turning on the switching element.・Equipped with a drive circuit that turns off the pulse peak current setting value when the terminal voltage detected by the voltage detector while the output current is flowing is below a specified voltage value for more than a certain period of time. This is what I did.

[For production]

In the power supply device for pulsed arc welding according to the present invention, the voltage detector detects the arc voltage while the output current is flowing, and identifies the load state (arc or short circuit). In response to the output of the voltage detector, the timer circuit starts counting from the moment the short circuit begins, and outputs a signal to the pulse peak current increase command circuit when the short circuit continues beyond a predetermined time. , a signal for increasing the set value is output to the pulse peak current setting circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of the present invention, and the configurations 1 to 8 in the figure are the same as those in FIG. 2. 9 is a voltage detector that detects the output terminal voltage; 10 is a timer circuit connected to the current detector iI5 and the voltage detector 9; l! is a pulse peak current increase command circuit connected to the timer circuit. Next, the operation of the pulse arc welding power source configured as described above will be described. Operations 1 to 8 are similar to those in the prior art. The voltage detector 9 detects the arc voltage and starts the timer #j10.
Enter. Current detector 5 detects the output current and similarly inputs it to timer circuit 10. In the timer circuit 10,
First, it is determined whether the signal from the current detector 5 is energized or not,
The signal from the voltage detector 9 is monitored only while the power is on. Next, the signal from the voltage detector 9 is compared with a preset value, and when the former becomes less than or equal to the latter, timing is started. From this point on, when this state (short circuit state) continues beyond a predetermined time, a signal is sent to the pulse peak current increase command circuit 11. While receiving this signal, the pulse peak current increase command circuit 11 issues a signal to the pulse peak current setting circuit 6 to increase the normal set value. As a result, the pulse peak current setting value becomes large, and the drive circuit 6 and switching element 4 operate until the short-circuit condition is released, and the pulse peak current value becomes large. When welding aluminum wire, MIG brazing wire, etc. using the pulsed arc welding power supply device configured in this way, when the wire plunges into the base metal at arc start or during welding, the wire Since a current larger than the peak current value during normal welding flows, sufficient Joule heat can be supplied to the wire to transfer it to an arc.゛

【Effect of the invention】

As explained above, according to the power supply device for pulsed arc welding according to the present invention: By inputting the output current signal from the current detector to the timer circuit, it is possible to determine whether or not an arc is occurring (
In other words, whether the voltage is on or off), the timer circuit accepts the signal from the voltage detector only when the voltage is on, and when the output is short-circuited due to high voltage when the voltage is off, the timer circuit We have created a welding power supply that can prevent malfunctions caused by the circuit receiving and receiving signals from the voltage detector and starting time measurement, as well as having good arc start performance and maintaining a stable arc condition unaffected by external disturbances. The effect is that it can be supplied.

[Brief explanation of the drawing]

FIG. 1 shows a schematic diagram of a power source for pulsed arc welding according to the present invention, and FIG. 2 shows a schematic diagram of a power source for pulsed arc welding according to the prior art. 1 ・Input terminal, 2... Transformer, 3... Rectifier, 4
...Switching element, 5. Current detector, 6. Pulse peak current setting circuit, 7. Drive circuit, 8. Output terminal, 9. Voltage detector, 10. Timer circuit, 1
1...Pulse peak current increase command circuit. Note that the same reference numerals in the drawings indicate the same components. Agent Masuo Oiwa (2 others) Figure 1 Figure 2 Procedural amendment (voluntary) 1. Display of incident Patent application Sho 62-260418
No. 2, Name of the invention, Power supply device for pulsed arc welding 3, Person making the amendment 5, Subject of the amendment - (1) Claims column 6 of the specification, Contents of the amendment (1) Claims of the specification Correct the range as shown in the attached sheet. 7. Attached documents (1) Document stating the entire text of the amended scope of claims
1 Document stating the entire text of the claims after amendment 2, Claims A transformer, a rectifier that rectifies the alternating current voltage on the secondary side of this transformer, and a rectifier connected to this rectifier to an arc load. In a pulsed arc welding power supply device consisting of a switching element that controls the output current, a current detector installed in the path of the output current and a current detector installed in the path of the output current, and a pulse peak current increase command circuit connected to the timer circuit, and a pulse peak current increase command circuit connected to the pulse peak current increase command circuit for setting the peak value of the output current. a setting circuit; and a drive circuit connected to the current detector and pulse peak current setting circuit to control on/off of the switching element; A power supply device for pulse arc welding characterized by increasing a pulse peak current setting value.

Claims (1)

[Claims] In a pulsed arc welding power supply device consisting of a transformer, a rectifier that rectifies the AC voltage on the secondary side of the transformer, and a switching element that is connected to the rectifier and controls the output current to the arc load, A current detector provided in the passage, a timer circuit connected to the current detector and the voltage detector, a pulse peak current increase command circuit connected to the timer circuit, and a pulse peak current increase command circuit connected to the timer circuit. A pulse peak current setting circuit for setting the peak value of the output current, and a drive circuit connected to the current detector and the pulse peak current setting circuit to control on/off of the switching element, the output current is energized. The terminal voltage detected by the voltage detector during
A power supply device for pulsed arc welding, characterized in that a pulse peak current setting value is increased when the voltage falls below a specified value for a certain period of time.