KR0136188B1 - Tig welding machine for alternating current - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC TIG welder, and more particularly, to an AC TIG welder that reduces the welding alternating frequency linearly with the magnitude of the welding current when the welding current is greater than the set current.

The technical means of the present invention comprises a polarity switching circuit for instructing polarity switching of an output command circuit and a secondary inverter circuit which obtain a command signal of an output regulator to generate an output current command signal, and an output current command signal in the output current command circuit. A polarity ratio control circuit for outputting the polarity ratio signal to the polarity switching circuit, and an output signal of the output current command circuit and the polarity switching circuit to receive the AC waveform signal. An AC waveform generation circuit output to the differential inverter circuit, a frequency conversion circuit for converting the output of the analog voltage into a frequency, and a trigger circuit for inputting the analog voltage into the conversion circuit from an arbitrary set current value.

Description

AC TIG Welding Machine

1 is a frequency switching circuit diagram of a typical AC TIG welding machine.

2 is a change diagram of a typical AC TIG welding frequency.

3 is a frequency switching circuit diagram of a conventional AC TIG welding machine.

4 is a change diagram of a conventional AC TIG welding frequency.

5 is a conventional AC TIG welding current waveform diagram.

6 is a view showing an optimum frequency for a conventional welding.

7 is a frequency switching circuit diagram of an AC TIG welder according to the present invention.

8 is a welding frequency change diagram of the AC TIG welder shown in FIG. 7 according to the present invention.

* Explanation of symbols for main parts of the drawings

1: 1 primary inverter circuit 2: welding transformer

3: secondary inverter circuit 4: torch

5: substrate 6: current detector

7: Output regulator 8: Output current command circuit

9: polarity ratio control circuit 10: polarity switching circuit

11: AC waveform generating circuit 12: polarity

20: trigger circuit 30: V-F conversion circuit

The present invention relates to an AC TIG (Tungsten-Inert-Gas) welder, and in particular, when the welding current is larger than the set current, the AC frequency is linearly reduced according to the magnitude of the welding current, so as to before and after the set current value. The present invention relates to an AC TIG welding machine which suppresses a sudden frequency change generated.

In general, in AC TIG welding, the AC frequency is suitably about 50 Hz to 100 Hz. However, the conventional AC frequency conversion is generally performed uniformly, and the change of frequency is about 100 Hz when the set current value is lower than or equal to a predetermined set current value, and operates at 100 Hz when the set current value is higher than the set current value. The time delay caused by the accumulation of carriers during switching of the device prevents damage of the power device.

The general AC frequency control method is briefly described as follows. If the DC voltage value output in proportion to the general set current value, for example, the O-500A class TIG welding machine is designed to reduce the frequency at 300A, which is approximately 3V, when the analog output of the set current value outputs O-5V The simplified circuit can be shown in Figure 1. Apply DC 3V to one input of the operational amplifier of Fig.1 and output DC voltage corresponding to the set current value from another input. In this way, if the user sets the current less than 300A, the output of the operational amplifier is-, and if it is over 300A, it is +. Thus, the desired switch was achieved by switching the switching switch of the frequency generator generating 50 and 100 Hz according to the negative and positive signals.

Such a typical AC TIG welding machine outputs only two frequencies before and after an arbitrary reference value. Therefore, a large change in the weld bead state can be brought about before and after the reference value.

In order to solve the above problems, it is necessary to be able to vary the frequency in proportion to the set current value. Of course, there may be something like Japanese Patent Application Laid-Open No. 4-27979 for the purpose of actively changing the output according to the set current value, but this patent does not change the AC frequency according to the set current, but changes the cleaning width. This process is a process that makes it difficult for a complete beginner to weld, and it was difficult for an experienced person to select an appropriate cleaning width according to a set welding current. In order to solve such a problem, Japanese Patent Laid-Open No. 4-279279 proposed a method of automatically setting the cleaning width according to the set current.

However, in general, the cleaning width is not simply determined by the current, but there are various determinants such as the material of the base material, the thickness, and the angle of the electrode team.

Referring to FIG. 3, the prior art will be briefly described. As shown in FIG. 1, 1 receives an AC power as a primary inverter circuit including a rectifier circuit and outputs an AC voltage of high frequency. The high frequency AC voltage is input to the primary side of the welding transformer 2, and the AC voltage suitable for welding is output from the secondary side of the welding transformer 2. This AC voltage is inputted to the secondary inverter circuit 3 including a rectifier, and is alternating between about 5 Hz and 100 Hz suitable for AC tag welding, and is output between the torch 4 and the base material 5. The output current changes the peak value I of the AC current waveform as shown in Fig. 5 according to the value set in the output regulator 7. Therefore, as the set current increases, instead of the peak value I, the pulse width is reduced, which becomes constant when viewed in terms of the area of the + section. However, in the conventional configuration, although the cleaning width is automatically changed as the set current becomes large, the difficulty of setting the cleaning width by an unskilled person can be solved. In consideration of the quality, there is a problem that the quality is somewhat lowered because the cleaning width is not changed.

On the other hand, the command signal set in the output regulator 7 is displayed as an output current command signal through the output current command circuit 8 and input to the AC waveform generating circuit 11. The AC waveform generating circuit 11 outputs a current command signal to the primary inverter circuit 1 to set the peak value I of the AC current waveform as shown in FIG. In addition, a detection signal from the current detector 6 is inputted to the AC waveform generating circuit 11 as an output current from the secondary inverter circuit 3, and feedback control of the output current is performed. The output current command signal of the output current command circuit 8 is also input to the polarity ratio control circuit 9.

Therefore, the ratio En (electrode minus ratio) En = {(T2 / T1 + T2)} x100 (%) of the electrode negative energization time of FIG. 5 is automatically set as shown in FIG. 6 according to the AC tag welding current value. do. Fig. 6 shows the optimum electrode minus polarity ratio En for alternating-tig welding. The polarity ratio display is input to the AC waveform generating circuit 11 as a polarity switching command through the polarity switching circuit 10. In this AC waveform generating circuit 11, the output waveform of the secondary inverter circuit 3 is controlled.

As described above, as shown in FIG. 5, the conventional invention may be effective to improve the difficulty of the unskilled workers by actively changing only the perth width according to the change of the set current at a certain frequency, but in terms of welding quality. Looking at it, the cleaning width is not simply determined as a function of the current size, but there is a problem of deteriorating welding quality without considering other various conditions, for example, welding materials, welding thicknesses, and team angles.

An object of the present invention is to provide an AC TIG welder to linearly reduce the AC frequency according to the magnitude of the welding current when the welding current becomes higher than the set current.

It is another object of the present invention to provide an AC TIG welding machine which reduces AC frequency linearly according to the magnitude of the welding current when the welding current becomes higher than the setting current, so that abrupt generations before and after the setting current value occur. It is to improve the quality of welding materials by suppressing frequency fluctuation.

As a means for achieving the above object, the present invention is an AC tag welding machine that outputs an AC waveform including a primary inverter circuit, a welding transformer, a secondary inverter circuit, the output current command by obtaining the command signal of the output regulator A polarity ratio control circuit that receives an output current command signal from an output current command circuit and an output current command circuit that generates a signal, sets an appropriate polarity ratio for the output current and outputs the polarity ratio signal, and a secondary according to the polarity ratio signal. The polarity switching circuit instructing the polarity switching of the inverter circuit, the output signal of the output current command circuit and the polarity switching circuit, and the detection signal of the current detector for detecting the AC output signal of the secondary inverter circuit are received to convert the AC waveform signal to AC waveform generating circuit output to the secondary inverter circuit, frequency conversion circuit for converting the output of analog voltage into frequency, and arbitrary And a trigger circuit for inputting an analog voltage into a conversion circuit from a set current value.

Hereinafter, with reference to the accompanying drawings, the present invention will be described.

7 is a frequency switching circuit diagram of the AC TIG welding machine according to the present invention, where 1 is a primary inverter circuit, which receives AC power and outputs high frequency AC voltage. 2 is a welding transformer, which outputs a high frequency AC voltage suitable for welding. 3 is a secondary inverter circuit, which includes a rectifier, and outputs an alternating voltage at an alternating current of about 50 Hz to 100 Hz suitable for AC tag welding.

4 is a torch, which mixes gas and air to create a flame. 5 is a base material, which is a metal material used for welding. 6 is a current detector, 7 is an output regulator, and the output current is adjusted using this. 8 is an output current command circuit, which receives a command signal from the output regulator and generates an output current command signal. 9 is a polarity ratio control circuit, which receives an output current command signal from the output current command circuit and sets an appropriate polar ratio for the output current. 10 is a polarity switching circuit, which indicates the polarity switching of the secondary inverter circuit. 11 is an AC waveform generating circuit, which receives the detection signal of the current detector and outputs the AC waveform signal to the primary and secondary inverter circuits.

20 is a circuit for triggering, which means that 100Hz is output below 250A, which is the middle value of the DC value (0-5V) of the set current, and from 250A (amps) to linearly decrease to 50Hz above the current. It works.

30 is a voltage-to-frequency conversion circuit, which causes the frequency to vary according to the DC voltage value with respect to the set current value.

Hereinafter, embodiments of the present invention will be described.

EXAMPLE

Unlike the method of simply changing the cleaning width according to the magnitude of the current, as in the conventional method, the present invention reduces the AC frequency linearly according to the magnitude of the current from 100 Hz to about 50 Hz when the setting current value is greater than the set current value. Therefore, the present invention suppresses abrupt frequency fluctuations before and after the set current value to obtain good welding quality.

The embodiment of the present invention is shown in FIG. 7, but has a configuration substantially the same as that of the conventional invention. However, between the output current command circuit 8 and the AC waveform generating circuit 11 during the present invention. The VF conversion circuit 30 was placed in the circuit so that the variable frequency was applied to the inverter circuit so that the frequency was varied according to the DC output value of the set current value.

So, for example, in the O-500A class welding machine, in order to output 100Hz at 250A or less, which is the middle value of DC value (O-5V) of the set current, and to gradually reduce the current to 50Hz, the VF conversion circuit 30 is used. The trigger circuit 20 for operating from 250A is placed in front. The trigger circuit 20 compares the output value of the output current command circuit 8 with an arbitrary value, and when the output of the operational amplifier becomes high, operates a switching switch to operate the output current command circuit 8 and the VF conversion circuit. (30) was connected so that the voltage was input to the VF conversion circuit (30) to achieve the desired purpose.

8 is a diagram showing a change in the set current and frequency according to the present invention, Figure 4 shows a change in the set current versus frequency of the conventional method, which shows that the frequency changes in a step-shaped rapidly at any current In contrast, FIG. 8 shows that the frequency may be gradually decreased when the value is greater than an arbitrary value in the case of the present invention.

In the present invention as described above, when the welding current is higher than the set current, the welding alternating frequency is linearly reduced according to the magnitude of the welding current, so that abrupt frequency fluctuations generated before and after the set current value are suppressed. There is an excellent effect to obtain an improvement in welding quality.

Claims (1)

In an AC tag welding machine that outputs an AC waveform including a primary inverter circuit 1, a welding transformer 2, and a secondary inverter circuit 3, an output current command signal is obtained by obtaining a command signal of the output regulator 7. A polarity ratio control circuit 9 for receiving an output current command circuit 8 for generating a signal and a polarity ratio signal for setting an appropriate polarity ratio for the output current upon receiving the output current command signal from the output current command circuit 8; And a polarity switching circuit 10 for instructing polarity switching of the secondary inverter circuit 3 according to the polarity ratio signal of the polarity ratio control circuit 9, the output current command circuit 8 and the polarity switching. An AC waveform generating circuit 11 for receiving an output signal of the circuit 10 and outputting an AC waveform signal to the primary and secondary inverter circuits 1 and 3, and a VF converter circuit 30 for converting an output of an analog voltage into a frequency. ), And the analog voltage is converted from an arbitrary set current value AC TIG welding machine, characterized in that the furnace includes a circuit 20 for the trigger to be input.