JPH01309785A - Middle pulse tig welding equipment - Google Patents

Abstract

PURPOSE:To simplify a control circuit of the title welding equipment by detecting a sound of an arc and controlling so that its intensity is maintained constant to prevent a signal from becoming unstable. CONSTITUTION:An arc sound signal during welding from a highly directional microphone 4 is sent to a filter amplifier circuit and a noise component is eliminated and amplified. Afterward, it is converted into a voltage signal ea capable of signal processing by a sound pressure converter 11. On the other hand, a reference voltage generator 13 generates the voltage eo to be reference of control and an upper limit comparator 13 and a lower limit comparator 14 compare the voltage signal ea and the voltage eo respectively. At the time of ea-eo<0, a torch raising relay 15 is actuated and a TIG torch 5 is raised, by which arc length is lengthened. At the time of ea-eo>0, a torch lowering relay 16 is actuated and the arc length is shortened. By this method, the stable arc length can be controlled.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a TIG welding device, and particularly to a middle pulse TIG welding device that can detect arc noise and maintain a constant arc length.
Regarding welding equipment.

[Conventional technology]

-i As a method of keeping the arc length constant in TIG welding, an arc length control method is used in which the torch is moved up and down so that the arc voltage is constant. Figure 3 shows the principle in block diagram form. Generally speaking, A V C (Arc V
This is called the oyage control method.

The arc voltage during welding is converted into a signal voltage Ea by the filter/amplifier circuit 10, and the voltage Ea is used as a reference for the arc length.
o is compared with the upper limit comparator 13 and the lower limit comparator 14. As a result, Ea -E.

If Ea - Eo > 0, the torch ascending relay 15 is operated to lengthen the arc length, and if Ea - Eo > 0, the torch descending relay 16 is operated to control the arc length to be constant.

By the way, in TIG welding, instead of keeping the arc current constant, a pulsed current with different heights is often used. As a result, the arc voltage naturally changes as shown in FIG. In AVC in this case, the arc length is kept constant by controlling the arc length only during the peak period when the pulse current is high or only during the base period when the current is low.

However, the frequency of the pulse current is relatively high
In 0Hz middle pulse TIG welding, the time for the voltage to stabilize is very short, making it difficult to detect the peak period, base period, and measure the voltage, making it difficult to maintain the arc length constant with ACV, which is controlled by the arc voltage. .

In addition, if you try to forcefully use the AVC method, you will need a circuit to determine the peak and base periods of the pulse current.
When the frequency changes, the measurement timing shifts and the arc voltage becomes unstable, making the circuit complicated.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, it is difficult to measure the voltage when a middle pulse current is used, so it is difficult to perform control to keep the arc length constant.

An object of the present invention is to enable stable arc length control even in TIG welding using middle pulse current.

[Means to solve the problem]

The above object is achieved by using the sound pressure generated by the arc column during welding instead of using the arc voltage as the signal for controlling the arc length. That is, the arc length can be kept constant by moving the torch up and down so that the arc sound is constant.

[Effect]

The size of the arc column in TIG welding changes rapidly as the current changes. Therefore, when a middle pulse current is used, a characteristic sound is generated depending on the height difference, frequency, and arc length of the current.

In other words, by converting the sound generated by the arc column into a voltage signal and moving the torch up and down so that the sound remains constant, the arc length can be kept constant.

(Embodiment of the Invention) Fig. 1 shows an overall configuration diagram of a middle pulse TIG welding apparatus according to the present invention. A TIG torch 5 is attached to a torch vertical driver 3 and moves up and down.
The IGI-chi 5 is equipped with a sound collecting microphone 4, which collects arc sound signals during welding to control the middle pulse TIG welding equipment.
Send to gJ road 2. Operations during welding are performed using the hand control box 9. Control circuit 2 performs all the controls necessary for welding, such as controlling the arc current, driving the torch up and down, and controlling the arc length to be constant.

FIG. 2 is a block diagram showing the principle of constant arc length control in the control circuit 2. The filter/amplifier circuit 10 removes noise from the signal from the sound collecting microphone 4 and amplifies it, and the sound pressure converter 11 converts the sound signal from the microphone 4 into a controllable voltage signal. The reference voltage generator 12 generates a signal voltage that can be compared with the output from the sound pressure converter 11, and the upper limit comparator 13 and lower limit comparator 14 compare the signal voltage, respectively, and operate the torch up relay 15 or torch down relay 16. TIG) - Raise and lower Chi 5.

The arc sound signal during welding from the sound collecting microphone 4 shown in FIG. 1 is sent to the filter/amplifier circuit 10 shown in FIG.
Noise components are removed and amplified.

Thereafter, the sound pressure converter 11 converts it into a voltage signal Ea that can be processed. On the other hand, a reference voltage generator 12 generates a voltage Eo that serves as a control reference, and an upper limit comparator 13 and a lower limit comparator 14 compare Ea and Eo, respectively.

When Ea Eo<Q, the torch raising relay 15 is activated to raise the TMCI-ch 5, thereby increasing the arc length. When Ea-Eo>O, the torch lowering relay 16 is activated to shorten the arc length.

In other words, if the strength of the sound generated by a TIG arc using a middle pulse current is constant, the strength of the arc sound can be determined by using the well-known phenomenon that if the current value, its height difference, and frequency are constant, it depends on the arc length. The arc length is kept constant by moving the TIG torch 5 up and down so that the value of the parameter becomes constant.

If welding conditions (for example, arc peak and base current, arc length, etc.) are changed during welding, the arc sound will also change accordingly, so a command indicating that the conditions have been changed is given to the reference voltage generator 12 for appropriate control. The basis of! $voltage EO
Change to

〔Effect of the invention〕

According to the present invention, since the arc sound is detected and controlled so that its intensity is constant, the signal does not become unstable and the control circuit can be simplified.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the overall configuration of a middle pulse TIG welding device according to an embodiment of the present invention, and Fig. 2 shows a circuit for controlling arc length constant among the control circuits of the middle pulse TIG welding device. Figure 3 is a block diagram showing the principle of a conventional arc length control device, Figure 4 is a block diagram showing the principle of a conventional arc length control device, and Figure 4 is a block diagram showing the principle of a conventional arc length control device.
FIG. 6 is a diagram showing a change in voltage when a pulse current is used in the G#@ contact. 1...Middle pulse TIG welding, 4...Sound collecting microphone, 5...T[G torch, 11...Sound pressure converter. Figure 1

Claims (1)

[Claims] The arc-dependent voltage is compared with the reference voltage, and based on the comparison result, the torch is raised and lowered to keep the arc length constant.
A middle-pulse TIG welding device characterized by having a middle-pulse TIG power source, a sound-collecting microphone that collects arc sound, and a sound pressure converter that converts arc sound into a voltage signal.