AU565763B2

AU565763B2 - Welding system for tig welding

Info

Publication number: AU565763B2
Application number: AU30173/84A
Authority: AU
Inventors: Heini Edberg
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-06-15
Filing date: 1984-05-25
Publication date: 1987-09-24
Anticipated expiration: 2004-05-25
Also published as: NO850569L; FR2548067B1; GB2156607B; FI850602A0; FR2548067A1; DE3490272C2; DK274283A; FI850602L; AU3017384A; DK152413B; CA1228896A; DE3490272T1; JPS60501548A; SE8500692L; DK274283D0; GB8503548D0; SE8500692D0; WO1985000024A1; GB2156607A

Description

Welding System for Tig Welding.

The available invention concerns an electronically operating circuit, which is meant to be mounted on operating welding rectifiers with a basic current circuit.

The known welding systems to Tig welding can be splitted into two systems dependent on the way on which the welding is started. The first system uses scrape ignition, when the voltaic arc is established by scraping the electrode against the welding subject until a spark is obtained. Though, this method will bring about a 'drag' in the material by start and stop, and wolfram material is left on the welding material, which means that the welding will not be good workmanship, In addition the welding electrode must be taken out and grinded frequently. Another system uses a contact free start by means of a high tension generator, which when the spark is established to the welding subject will start the voltaic arc. The drawback by this system is that. the spark will move in a circle on the welding subject, and you can not precisely control where the welding is started. Furthermore this system is very expensive.

From English patent specification no. 2.o54.293 a welding system is known, which counteracts the drawbacks of the scrape ignition. By this system you obtain a soft start by coupling together a high tension via a seperate transformer winding with a belonging rectifier, which is synchronized with the mains frequency, whereafter you, when the voltaic arc is established, electronically changes over to a normal slope-up circuit with a new rectifier. Meanwhile it is a rather expensive method to advanced scrape ignition which also includes an expensive choke coil. The user also has the posibility of getting an electric shock if he uses filler metal.

The invention differs from the known systems because you do not use high tension by start, and the adjustment takes place as a current regulation.

The invention consists of an electronically operated circuit which is meant to be mounted on operated welding rectifiers with basic current circuit.

The peculiar thing about the invention is that the welding electrode can be placed directly on the welding sub-ject without the welding voltaic arc has been established, because only the basic current on 3-8 A will get into the electrode. In that moment the electrode is lifted from the welding subject the basic current will be raised to twice as much as the presetted welding current, and a voltaic arc is established. Hereafter the current is lowered immediately to the value the slope-up function has achieved. The slope-up function of the operated circuit regulates hereafter the current up to the presetted welding current. If the welding subject is touched during the welding the operated circuit will regulate the welding current down to basic current niveau, which protects the electrode.

When the button on the welding handle is slipped, a down-slope will take place, which bring about that the welding current is slowly lowered to basic current niveau and the welding stops. The slope functions causes that you avoid the 'drag' in the material.

During the welding with the presetted welding current it is possible by trigging with a burner switch to pulsate the welding current for controlling the melting bath. The control circuit regulates also the gasstream in the magnetic valve in a way so you both get for- and afterstreaming of argon. This is done to make the start easier and to avoid oxidizing the electrode during the cooling.

The advantages of the invention are that a 'drag' is avoided and that you very precisely can decide where to start the welding.

The invention will in the following part be described according to the invention,

Fig. 1 shows a block diagram to use by practising the invention.

The welding system has to be connected with a thyrister opereted welding rectifier with internal basic current circuit. The welding is described with MODE switch (ll) in position Tig welding. The wolfram electrode on the welding handle (6) is placed on the welding subject. The switch on the welding handle (l) is served, and maintenance circuit (2) is activated. Hereby the magnetic valve (3) opens and the time for the gasstreaming (circle 4 ) starts. After the gasstrearning has stopped the basic current circuit on-off (5) is activated, which turn on the basic current to the electrode (6). When the electrode is lifted very little from the welding subject the welding voltaic arc and the idle voltage control (7) is activated. This will activate the startpulse circuit (8). This implies that the welding current circuit (9) shortly lifts the welding current to establish a stable welding voltaic arc - bigger than the value of the setted value on the control. After a stable voltaic arc is obtained the current will fall to a little above basic current value. Simultaneously with the voltaic arc is established the control of the welding voltaic arc (7) will start for the slope-up function (10). This implies that the welding current for a short time will raise to presetted value-control (12). When you wish to stop the welding the Tig burner switch (l) is turned off, by means of which the slope-down regulation (lo) starts to regulate down through the regulation circuit (9). When the regulation to the basic current niveau is obtained the holding circuit (2) is zero-setted and the basic current circuit on-off (5) turns off for the basic current in the welding rectifier. At the same time starts the time for the gas afterstreaming (4). After that the magnetic valve (3) is turned off, after the gas afterstreaming has stopped. The time for afterstreaming avoid oxidizing the electrode during the cooling.

By use of the system to tack-welding the MODE switch is placed in position, tack-welding. The welding works in the same way, as by Tig welding though the up and down slope time is shortened to milliseconds.

By use of the system to electrode welding the MODE switch is placed in position, electrode welding. This implifies that the basic current circuit is constantly activated. The slope function (lo) and the gas regulating circuit (4) are uncoupled. You can now carry out a normal electrode welding with coupled up equipment.

Claims

P a t e n t C l a i m s.

1. Tig operating electronics is c h a r a c t e r iz e d by that you, in the beginning phase by shortly lifting and thereafter lowering the welding current in the welding rectifier with basic current establishes a stable voltaic arc.

2. Tig operating electronics according to claim 1 is c h a r a c t e r i z e d by having installed compensation in connection with start and a slow welding current and at the same time having installed automatic slope functions.

3. Tig operating electronics according to claim 2 is c h a r a c t e r i z e d by that it protects the welding electrode and welding subject during start, in a way so wolfram is not left on the welding material.