JPS6268676A - Dc arc welding machine - Google Patents

Abstract

PURPOSE:To set the conditions suitable for the wire diameter and to increase the welding start characteristic by changing the hot starting voltage level outputted between the consumable electrode and base metal for a fixed time at welding start time by the diameter of the consumable electrode. CONSTITUTION:The certain output voltage v2 which differs from the welding output voltage v1 while under welding is outputted between a consumable electrode 1 and base metal 2 by the reference voltage which is decided in the inner part of the hot voltage reference voltage generating circuit 18 with changing function when the welding start signal is transmitted to an invertor part 7 via an output control circuit 11. The plural functions which decide the reference voltage corresponding to the plural wire diameter setting values at the inside of a wire diameter setting circuit 19 are prepared inside the circuit 18 and the wire diameter setting value selected by the circuit 19 is transmitted to the circuit 18. Thereupon, the reference voltage is decided by the function corresponding to the wire diameter set value, the reference voltage thereof is transmitted to the invertor part 7 via an analog switch 17 and output control circuit 11 and the output voltage accorded with the wire diameter is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention has an output control element such as a power transistor that can be controlled by an electric signal, and is suitable for arc welding loads generated between a consumable electrode and a base metal. The present invention relates to a DC arc welding machine having a main circuit that supplies DC power.

BACKGROUND OF THE INVENTION The structure of a conventional arc welding machine is shown in FIG. In Fig. 2, 1 is a consumable electrode, 2 is a base material, 3 is an electrode feeding motor and feeding device, 4 is a welding part, 5 is a rectifying part, 6 is a smoothing capacitor, 7 is an inverter part, 8 ( is a transformer, 9 is a rectifier, 10 is a reactor, 11 (output control circuit, 12 is a shunt resistor, 13 is a current detection circuit, 14 is a timer circuit, 16) is an output voltage setting circuit, 16 is a hot voltage reference voltage generation The circuit 17 is an analog switch.

The operation of the conventional DC arc welding machine configured as described above will be explained below.

AC power input to the DC arc welding machine from an input terminal is rectified by a rectifier 5 and smoothed by a smoothing capacitor 6. After that, the inverter section 7 converts the power into AC power, and the transformer 8 lowers the voltage to a voltage suitable for welding.
It is rectified again by the rectifier 9 and converted into DC power. Then, it is supplied to the welding part consisting of the consumable electrode 1 and the base material 2 via the reactor 10 for improving welding characteristics. The consumable electrode 1 ('i) is fed at a constant speed by an electrode feeding motor and a feeding device 3, and welding is performed between the consumable electrode 1 and the base metal 2. The output voltage is adjusted by The signal from the output voltage setting circuit 15 is transmitted to the output control circuit 11 via the analog switch 1, and controls the switching duty of the power transistors, etc. that constitute the inverter section 7. Now, immediately before and at the start of welding, the analog switch 17 is
is connected to the hot voltage reference voltage generation circuit 16, and when a welding start signal is transmitted to the inverter section 7 via the output control circuit 11, a certain function F1 is generated within the hot voltage reference voltage generation circuit 16. Based on the reference voltage determined in , a constant output voltage v2 different from the welding output voltage v1 during welding is output between the consumable electrode 1 and the base metal 2. When welding is started, the m, )'NN feedback signal is taken in via the shunt resistor 12 and the current detection circuit 13, and this D signal is sent to the timer circuit 14. After a certain delay time T1 has elapsed, the analog switch 17 can be conveyed to. In response to the welding current feedback signal, the analog switch 17 is switched to the output voltage setting circuit 15, and the signal set by the output voltage setting circuit 15 is transmitted to the inverter section 7 via the output control circuit 11.
The output pressure between the consumable electrode 1 and the base material 2 becomes the welding output voltage v1 during welding.

By controlling as described above, the amount of energy supplied between the consumable electrode 1 and the base material 2 at the time of starting welding is set to an appropriate value, so that good welding starting characteristics can be obtained. This energy supplied for a certain period of time at the start of welding will be referred to as the hot start voltage.

The problem to be solved by the invention is that, according to the conventional DC arc welding machine as described above, the hot start voltage has exactly the same value due to the above-mentioned function Fl, regardless of the thickness of the consumable electrode. . On the other hand, the optimum value of the hot start voltage varies depending on the thickness of the consumable electrode. General:・I-i! The greater the ambiguity of power consumption, the greater the need for a thicker hot start voltage at the start of welding, and excessive or insufficient hot start voltage will have an adverse effect on the welding start time. However, with a conventional DC arc welding machine: ``I・Portrait?'' Because it is not possible to change the hot start voltage depending on the size of the raw electrode, it is suitable for various diameters of consumable electrodes. It was not possible to supply a hot start voltage.

Solution to IX In order to solve this problem, the present invention provides a main circuit that supplies DC power to the arc welding load generated between the consumable electrode and the base metal. At the start of welding, a welding start signal is used to output a constant output voltage between the consumable electrode and the base metal (which is different from the welding output voltage during welding), and after a certain period of time after the start of welding, A DC arc welding machine that outputs a clamp welding output quasi-pressure is provided with a means for switching the level of the constant output mixed pressure described in QiI according to the thickness of the consumable electrode. This makes it possible to appropriately set the constant output voltage that is output for a certain period of time after the start of welding, that is, the hot start voltage, according to the thickness of the consumable electrode.

EXAMPLE An example of the present invention will be explained with reference to FIG. Divided into Figure 1, 1.2, 3, 4, 5, 6, 7, 8° 9. 10, 11
．． 12, 13, 14, 16, and 17 are the same consumable electrodes, base material, electric oven feeding motor, and feeding device as in the conventional example, respectively;
Welding section, rectification section, smoothing capacitor, inverter section, transformer, rectifier.

They are a reactor, an output control circuit, a shunt resistor, a current detection circuit, a timer circuit, an output voltage setting circuit, and an analog switch. 18 is a hot voltage reference voltage generation circuit having a function of switching a conversion function of an output voltage setting signal; and 19 is a wire diameter setting circuit.

The operation of the DC arc welding machine constructed as described above will be explained below. AC power input to the DC arc welding machine from the power supply input terminal is rectified by a rectifier 5 and smoothed by a smoothing capacitor 6. The power is then converted back into alternating current power by an inverter section made up of switching elements such as power transistors. Next, the voltage is stepped down to a voltage suitable for welding by a transformer 8, rectified again by a rectifier 9, converted to DC power, and supplied to the welding part consisting of the consumable electrode 1 and the base material 2 via the reactor 10 for improving welding characteristics. be done. The consumable electrode 1 is fed at a constant speed by an electrode feeding motor and a feeding device 3, and welding is performed between the consumable electrode 1 and the base material 2. The output voltage is adjusted by transmitting a signal from the output voltage setting circuit 15 to the output control circuit 11 via the analog switch 17 to control the switching duty of output control elements such as power transistors that constitute the inverter section. Is going.

Now, at the time of starting welding, the analog switch 1 is connected to the hot voltage reference voltage generation circuit 18 with a switching function, and when a welding start signal is transmitted to the inverter section 7 via the output control circuit 11.

A certain reference voltage V determined within the hot voltage reference voltage generation circuit 18 with a switching function generates a constant output voltage v2 different from the welding output voltage v1 between the consumable electrode 1 and the base metal 2 during welding. Output.

and the hot voltage base voltage generation circuit 1 with switching function.
8 includes a plurality of functions F(x); (x-1, 2,・・・・・・
) is prepared and an arbitrary wire diameter setting value selected by the wire diameter setting circuit 19 is transmitted to the hot voltage reference voltage generator with switching function 18, the function F corresponding to the wire diameter setting value is A reference voltage V is determined by (x), and this reference voltage V is transmitted to the inverter section 7 via the analog switch 17 and the output control circuit 11, thereby controlling to output an output voltage v2 according to the wire diameter. ing. When welding is started, a welding current feedback signal is input via the shunt resistor 12 and the current detection circuit 13, and this signal is sent to the timer circuit 14.
After a delay time T1, the analog switch 1 is turned on. In response to the welding current feedback signal, the analog switch 17 is switched to the output setting circuit 16, and the signal set by the output voltage setting circuit 15 is transmitted to the inverter section 7 via the output control circuit 11.
The output voltage between the consumable electrode 1 and the base material 2 becomes the welding output voltage v1 during welding.

Effects of the Invention According to the present invention, the real start voltage level output between the consumable electrode and the base metal during a certain period of time at the start of welding can be switched depending on the thickness of the consumable electrode, and the voltage level that Since suitable conditions can be set, there is an excellent effect that welding start characteristics can be improved regardless of the wire diameter.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a DC arc welding machine according to the present invention, Figure 2 is a circuit diagram of a DC arc welding machine according to the present invention;
The figure is a circuit diagram of a conventional DC arc welding machine. 1...Consumable electrode, 2...Base material, 3...
Electrode feeding electric motor and feeding device, 4... Welding section, 5... Rectifying section, 6... Smoothing capacitor, 7... Inverter section, 8...Transformer, 9...Rectifier, 10... Reactor, 11... Output control circuit, 12...
Shunt resistor, 13-, = current detection circuit, 14...
・Timer circuit, 15 ・・Output voltage setting circuit, 16・
...Hot voltage reference voltage generation circuit, 1. Analog switch, 18.. E with switching function,) Voltage reference voltage generation circuit, 19. Wire diameter setting circuit.

Claims (1)

[Claims] It has a main circuit that supplies DC power to the arc welding load generated between the consumable electrode and the base metal, and a welding current detection circuit that detects when welding current flows, and when welding is started and the welding For a certain period of time after the current detection circuit outputs the detection signal, it outputs a certain output voltage that is different from the welding output voltage during welding and has a value higher than the welding output voltage, and after the certain period of time has elapsed, the welding output A DC arc welding machine that controls voltage output, the DC arc welding machine comprising means for switching the level of the constant output voltage depending on the thickness of the consumable electrode.