JPH0635058B2 - DC arc welding machine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an output control element such as a power transistor that can be controlled by an electric signal, and can prevent an arc welding load generated between a consumable electrode and a base metal. The present invention relates to a DC arc welding machine having a main circuit for supplying DC power.

2. Description of the Related Art The configuration of a conventional arc welder 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, and 8 is 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, 17 Is an analog switch.

The operation of the conventional DC arc welder configured as described above will be described below.

The AC power input from the input terminal to the DC arc welding machine is rectified by the rectifier 5 and smoothed by the smoothing capacitor 6. After that, it is converted into AC power again by the inverter unit 7, and is stepped down to a voltage suitable for welding by the transformer 8,
It is rectified again by the rectifier 9 and converted into DC power. Then, it is supplied to the welded portion composed of the consumable electrode 1 and the base material 2 through the welding property improving reactor 10. 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 the output voltage setting circuit 15
Is transmitted to the output control circuit 11 via the analog switch 17 to control the switching duty of the output control element such as the power transistor constituting the inverter unit 7. Immediately before and at the start of welding, the contacts of the analog switch 17 are connected to the hot voltage reference voltage generating circuit 16, and when a welding start signal is transmitted to the inverter unit 7 via the output control circuit 11, the Inside the hot voltage reference voltage generation circuit 16,
A constant output voltage V2 different from the welding output voltage V1 during welding is output between the consumable electrode 1 and the base material 2 by the reference voltage determined by a certain function F1. When welding is started, a welding current feedback signal is taken in via the shunt resistor 12 and the current detection circuit 13, and this signal is transmitted to the analog switch 17 after a delay time T1 in the timer circuit 14 has elapsed. The analog switch 17 is operated by the welding current feedback signal.
Is switched to the output voltage setting circuit 15, and the signal set by the output voltage setting circuit 15 is applied to the output control circuit 11.
The output voltage between the consumable electrode 1 and the base metal 2 is transmitted to the inverter unit 7 via the welding output voltage V1 during welding. By the control as described above, the amount of energy supplied between the consumable electrode 1 and the base material 2 at the start of welding is set to an appropriate value, and good welding start characteristics are obtained.
This energy supplied for a fixed period at the start of welding will be referred to as a hot start voltage.

Problems to be Solved by the Invention According to the conventional DC arc welding machine as described above, the hot start voltage has exactly the same value by the function called F1 regardless of the thickness of the consumable electrode. . On the other hand, the optimum value of the hot start voltage depends on the thickness of the consumable electrode. Generally, the larger the diameter of the consumable electrode, the larger the hot start voltage required at the start of welding, and the excess or deficiency of the hot start voltage adversely affects the welding start characteristics. However, the conventional DC arc welder cannot change the value of the hot start voltage depending on the diameter of the consumable electrode, so it is impossible to supply the optimum hot start voltage to each consumable electrode of various diameters. Met.

Means for Solving the Problems In order to solve such problems, according to the present invention, a main unit including an inverter unit for supplying DC power to an arc welding load generated between a consumable electrode and a base material is provided. A welding current detection circuit having a circuit is provided for detecting that a welding current has flowed, a timer circuit for measuring a fixed time after welding is started and the welding current detection circuit outputs a detection signal, and a first voltage is provided. Control for outputting a constant output voltage having a value higher than the welding output voltage, which is different from the welding output voltage during welding until the constant time elapses from the application of, and outputting the welding output voltage after the constant time elapses. The DC arc welding machine for carrying out the method comprises means for switching the level of the constant output voltage according to the thickness of the consumable electrode.

With the above-described configuration, the present invention appropriately sets the constant output voltage output during a fixed time after starting welding, that is, the hot start voltage, in accordance with the thickness of the consumable electrode, in the welding machine including the inverter unit. It will be possible.

Embodiment An embodiment of the present invention will be described with reference to FIG. In FIG. 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1
1, 12, 13, 14, 15, and 17 are consumable electrodes, base materials, electrode feeding motors and feeding devices, welding parts, rectifying parts, smoothing capacitors, inverter parts, transformers, which are the same as in the conventional example. Rectifier, reactor, output control circuit, shunt resistor, current detection circuit, timer circuit, output voltage setting circuit, analog switch. Reference numeral 18 is a hot voltage reference voltage generating circuit having a function of switching the conversion function of the output voltage setting signal, and 19 is a wire diameter setting circuit.

The operation of the DC arc welding machine configured as described above will be described below. The AC power input from the power input terminal to the DC arc welding machine is rectified by the rectifier 5 and smoothed by the smoothing capacitor 6. Then, it is converted into AC power again by the inverter unit 7 composed of a switching element such as a power transistor. Next, it is stepped down to a voltage suitable for welding by the transformer 8, re-rectified by the rectifier 9 and converted into direct current power, and supplied to the welded portion composed of the consumable electrode 1 and the base metal 2 through the reactor 10 for improving welding characteristics. To 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 controlling the switching duty of an output control element such as a power transistor that constitutes the inverter unit 7 by transmitting the signal of the output voltage setting circuit 15 to the output control circuit 11 via the analog switch 17. Is going.

At the start of welding, the contact of the analog switch 17 is connected to the hot voltage reference voltage generating circuit 18 with a switching function. When the welding start signal is transmitted to the inverter section 7 via the output control circuit 11, the switching function is changed. A certain output voltage V2 different from the welding output voltage V1 during welding is output between the consumable electrode 1 and the base metal 2 by a certain reference voltage V determined inside the attached hot voltage reference voltage generating circuit 18. . A plurality of functions for determining the reference voltage V corresponding to two or more wire diameter setting values inside the wire diameter setting circuit 19 are provided inside the hot voltage reference voltage generating circuit 18 with the switching function. F (x); (X = 1, 2, ...
...) is provided, and when an arbitrary wire diameter set value selected by the wire diameter setting circuit 19 is transmitted to the hot voltage reference voltage generator 18 with a switching function, a function F corresponding to the wire diameter set value is prepared. The reference voltage V is determined by (x), and the reference voltage V is transmitted to the inverter unit 7 via the analog switch 17 and the output control circuit 11 so that the output voltage V2 corresponding to the wire diameter is output. ing. When welding is started, a welding current feedback signal is taken in via the shunt resistor 12 and the current detection circuit 13, and this signal is transmitted to the analog switch 17 after a delay time T1 in the timer circuit 14. The contact of the analog switch 17 is set to the output setting circuit 1 by the welding current feedback signal.
5, the signal set by the output voltage setting circuit 15 is transmitted to the inverter unit 7 via the output control circuit 11, and the output voltage between the consumable electrode 1 and the base material 2 is the welding during welding. The output voltage becomes V1.

EFFECTS OF THE INVENTION According to the present invention, in a welding machine equipped with an inverter, the hot start voltage level output between the consumable electrode and the base material is switched according to the thickness of the consumable electrode at a certain time at the start of welding. It is possible to set the optimum switching time, and since the most suitable condition can be set for each wire diameter, it is possible to improve the welding start characteristics regardless of the wire diameter. is there.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a DC arc welding machine according to the present invention, and FIG.
The figure is a circuit diagram of a conventional DC arc welding machine. 1 ... Consumable electrode, 2 ... Base material, 3 ... Electrode feeding motor and feeding device, 4 ... Welding part, 5 ... Rectifying part, 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 generating circuit, 17 ... Analog switch, 18 ... Hot voltage reference voltage generating circuit with switching function, 19 ... Wire diameter setting circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norikazu Osaki, 1006, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References: Syo 59-148176 (JP, U)

Claims (1)

[Claims] Claim: What is claimed is: 1. A welding current detection for detecting a welding current flow, comprising a main circuit having an inverter section for supplying DC power to an arc welding load generated between a consumable electrode and a base material. A circuit is provided, and a welding current detection circuit is provided with a timer circuit that measures a fixed time after the welding current detection circuit outputs a detection signal, and a welding output voltage during welding until the fixed time elapses from the application of the initial voltage In the DC arc welding machine which outputs a constant output voltage having a value higher than the welding output voltage and controls the welding output voltage to be output after the predetermined time has elapsed, the level of the constant output voltage is consumable. A DC arc welding machine equipped with a means for switching depending on the thickness of the electrode.