JPS61147972A - Power source for consumable electrode type welding - Google Patents

Abstract

PURPOSE:To obtain smooth and uniform arc starting performance in a power source for welding which executes arc welding while feeding automatically a welding wire which is a consumable electrode by providing a welding current detecting circuit and wire short-circuit detecting circuit in combination to said device. CONSTITUTION:The wire short-circuit detecting circuit 15 connected between a pair of the output terminals of the power source for welding in the block diagram of the power source for welding. The circuit 15 outputs a signal S by discriminating whether the welding output voltage is above or below the specified voltage and discriminating whether the welding wire 9 is short-circuited by contacting with work 10 or generates an arc without contact therewith from the result of said discrimination. The welding current detecting circuit 14 outputs a detection signal A by detecting the presence or absence of the welding current. An output control circuit 13 is inputted with the signals A, S and outputs the signals V, M to a welding output control element 4 and a welding wire feed motor 12, respectively. The slow down and hot start conditions are thus continued until the wire short-circuit is eliminated regardless of the top end shape, diameter, material, etc. of the wire and the purpose is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a welding power source that performs arc welding by automatically feeding a welding wire, which is a consumable electrode.

Conventional technology Conventional welding power sources of this type employ so-called wire slowdown control, which reduces the wire feed speed at the start of welding compared to steady welding, in order to smooth the arc generation at the start of welding, and controls the welding output to a steady state. So-called hot start control, which increases the ratio compared to that during welding, has been a conventional ratio control method.

The trigger signal for switching from the wire slowdown or hot start state to the steady state is generally based only on a welding current detection signal that detects the presence or absence of welding current. That is, the conventional welding power source of this type has the configuration shown in FIG. In this Fig. 4, 1 is a welding power input terminal, 2 is a welding transformer, 3 is a rectifier,
4 is a welding output control element, and 6 is a reactor for adjusting welding performance. 6 is a shunt, 7 is a power supply output terminal for welding, 8 is a power supply tip for energization, 9 is a welding wire, 1o is an object to be welded, 11 is a welding arc, 12 is a wire feeding motor,
13 is an output control circuit, and 14 is a welding current detection circuit.

In the above configuration, the welding current detection circuit 14 detects the detection signal of the shunt 6 and outputs the presence or absence of welding current to the output control circuit 13 according to the input signal, and the output control circuit 13 controls the wire feeding motor according to the A signal. An M signal for switching between slowdown speed and steady welding speed is output to 12, and at the same time, a V signal is output to welding output control element 4 for switching between hot start output and steady welding output. FIG. 5 is a timing chart of each signal in FIG. 4. Incidentally, as shown at time td4C in FIG. 6, the V signal and the M signal may be switched to the steady state with a slight delay from the detection of the input signal.

Problems to be Solved by the Invention In the conventional example described above, the tip shape of the welding wire 9 at the start of welding depends only on the welding current detection signal as a signal for switching from the slow-down condition and the hot-stern condition to the steady condition. It is possible to detect variations in the time taken to generate an arc due to differences in the number of wires, etc., resulting in wire breakage or wire burning out, making it impossible to obtain uniform arc starting performance. Further, there is a problem in that it is necessary to deal with differences in wire diameter and wire material by changing slow-down conditions, hot-start conditions, and time td in FIG. 6. Even if such measures are taken, arc starting performance will not be uniform, especially if the wire is hard to melt due to its low specific resistivity, such as aluminum wire, and the wire will continue to be molten and no arc will occur. As a result, excessive resistance force is applied to the wire, causing a wire buckling accident, and excessive wire burning causes the molten wire 9 to explode with an explosion sound and the energized tip 8km91
My friend who caused accidents such as playing on jr.

Ninth Means for Solving the Problems In order to solve the above conventional problems, the present invention provides a welding current detection circuit that detects the presence or absence of welding current and outputs a detection signal;
A wire short circuit that determines whether the welding output voltage is above or below a certain value, and based on this judgment result, determines whether the welding wire is short-circuited by contact with the workpiece or a welding arc is generated without contact, and outputs a signal. a detection circuit; and an output control circuit which receives output signals from the welding current detection circuit and the wire short circuit detection circuit, and outputs a welding output control element, a welding wire feed motor, and a KIIJ output signal; The output control circuit detects both that the output signal of the welding current detection circuit is in a state where welding current is present and that the output signal of the wire short circuit detection circuit is in a state that a non-contact arc is generated at the time of arc start at the start of welding. After detection, the control output signal is switched to the wire feed motor so that the wire feed speed is changed from the so-called slow-down speed, which is lower than during steady welding, to the steady welding speed, and the welding output is lowered than during steady welding. The control output signal is switched and outputted to the welding output control element so that the high output hot start output becomes the steady welding output.

Operation In the above configuration, the output control circuit is configured such that the output signal of the welding current detection circuit is in a state where welding current is present at the time of arc start at the start of welding, and the output signal of the wire detection circuit is in a state in which a non-melting arc is generated. In this case, the wire feeding speed is controlled to be a so-called slowdown speed and steady welding speed that is lower than that during steady welding, and the welding output is changed from a hot start output that is higher than that during steady welding to a steady welding speed. The shape of the wire tip is controlled so that the welding output is controlled.

Regardless of the wire diameter, wire material, etc., the slowdown condition and hot start condition are continued until a wire short circuit is detected, and the wire is sufficiently heated and melted to ensure smooth and uniform arc start performance. It will be done.

Practical Hakama Examples Examples of the present invention will be described below with reference to FIGS. 1 to 3.

In FIG. 1, the same components as those shown in FIG. 4 are designated by the same numbers, and their explanations will be omitted.

16 is a wire short circuit detection circuit connected between a pair of welding power supply output terminals, which determines whether the welding output voltage is above or below a certain value, and based on this judgment result, the welding wire 9 comes into contact with the workpiece 1o. It determines whether there is a short circuit or a non-contact welding arc is generated and outputs a signal S.

Welding current detection circuit 14 detects the presence or absence of welding current and outputs detection signal A.

The output control circuit 16 receives the detection signal A and the signal S, and outputs the signal V and the signal M to the welding output control element 4 and the welding wire feed motor 12, respectively.

Next, the operation of the above configuration will be explained with reference to FIGS. 2 and 3. At the start of welding, the output control circuit 13 sends an output signal to the wire feed motor 12 with a slower slowdown condition than during steady welding. At the same time, a hot start condition output signal is sent to the welding output control element 4 to command a higher output than during steady welding. When the welding wire 12 fed under slow-down conditions contacts the workpiece 1o and short-circuits it (time M in FIG. 2), the welding current detection signal A outputs a welding current state. At the same time, the wire short circuit detection signal S outputs the wire short circuit state. The output control circuit 13 receives a signal indicating that welding current has been detected, but also receives a wire short circuit signal at the same time, so the command signal M to the wire feed motor 12 remains in the slowdown condition, and the welding output control element 4 command signal V to
remains under the hot start condition. As these control conditions continue, the welding wire is sufficiently heated and melted to generate an arc at time t2 in FIG. As a result, the wire short circuit detection signal S is inverted to a non-contact state, so the output control circuit 13 outputs output signals M and V commanding steady welding conditions to the wire feed motor 12 and welding output control element 4, respectively. . The above-mentioned effects realize a smooth and uniform arc start.

Note that the output control circuit 13 is configured by, for example, a microcomputer, and according to the program shown in FIG.
Controls the above operations.

The welding current detection circuit 14 uses, for example, a comparator to determine whether or not a welding current is being applied, depending on whether the signal value from the shunt 6 is above or below a certain value. Similarly, wire short circuit detection circuit 15
For example, a comparator is used to determine whether the output voltage of the welding power source is above or below a certain value and whether or not there is a shear wire short circuit.

Effects of the Invention As is clear from the above explanation, according to the present invention, the speed is slowed down until the wire short circuit is released, regardless of the wire tip shape, wire diameter, wire material, etc.

Since the hot start condition is continued, the wire is sufficiently heated and melted, and smooth and uniform arc start performance can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a consumable electrode type welding power source showing one embodiment of the present invention, Fig. 2 is a signal waveform diagram of the main part of Fig. 1, Fig. 3 is a flowchart of the main part, and Fig. 4 5 is a block diagram of a conventional consumable electrode type welding power source, and FIG. 5 is a signal waveform diagram of the main part thereof. 4... Welding output control element, 9... Welding wire, 1o... Work to be welded, 12...
・Wire feeding motor, 13... Output control circuit, 14-... Welding current detection circuit, 15...
Wire short circuit detection circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure A Figure 3 “ψ 1

Claims (1)

[Claims] A welding current detection circuit detects the presence or absence of welding current and outputs a detection signal, and it determines whether the welding output voltage is above or below a certain value, and based on this judgment result, it determines whether or not the welding wire is short-circuited by contact with the workpiece. A wire short-circuit detection circuit that determines whether a welding arc is generated due to contact and outputs a signal, and a welding output control element and a welding wire feed that receive the output signals of the welding current detection circuit and the wire short-circuit detection circuit as inputs. and an output control circuit that outputs a control output signal to the motor, and the output control circuit detects that the output signal of the welding current detection circuit is in a welding current state at the time of arc start to start welding, and that the wire short circuit is detected. After detecting that both the output signals of the detection circuit indicate non-contact arc generation, the wire feeding speed is changed from a so-called slowdown speed, which is lower than that during steady welding, to a steady welding speed. A consumable electrode characterized in that the control output signal to the motor is switched and the control output signal is switched and outputted to the welding output control element so that the welding output changes from hot start output, which is higher output than during steady welding, to steady welding output. Type welding power source.