RU2121416C1 - Welding apparatus - Google Patents

Abstract

FIELD: welding processes and equipment in different branches of machine engineering. SUBSTANCE: apparatus includes transformer, thyristors connected in antiparallel, circuit for controlling thyristor operation, capacitor for cutting off thyristors. Magnetic circuit of transformer has variable cross section providing equal values of maximum magnetic density along its whole length at operation of apparatus. Thyristor control circuit automatically eliminates idle mode of transformer. Mass of magnetic circuit is reduced by 40 %. EFFECT: improved design of transformer allowing to lower losses in magnetic circuit, reduced size, mass and cost of apparatus. 3 dwg

Description

 The invention relates to the field of welding.

 Closest to the proposed is a device for welding, described in [1]. The device consists of a welding transformer, antiparallel thyristors, locking capacitance thyristors and thyristor control circuits.

The disadvantages of the device:
1. Increased losses in the steel of the magnetic circuit.

 2. Uneven loading of the magnetic circuit.

 These drawbacks are due to the fact that during operation, transformers under load, the values of maximum magnetic induction in different parts of the magnetic circuit are very different.

 The material of the transformer magnetic circuit in the region of the primary winding is in a state of deep saturation, and in the region of the secondary winding is unsaturated.

 As a result, the cross section of the magnetic circuit in the region of the secondary winding is poorly used, and in the region of the primary winding is overloaded, which leads to an increase in losses in steel in proportion to the square of the increase in maximum magnetic induction in the material of the magnetic circuit.

 Overcoming these drawbacks is achieved by the fact that the welding device consists of a transformer with a magnetic circuit whose cross-sectional area smoothly changes from the maximum value in the primary winding area to the minimum value in the secondary winding of the welding transformer, antiparallel thyristors in the primary winding circuit of the welding transformer, control circuit thyristors and a capacitor connected in parallel to the secondary winding of the welding transformer.

 When the inventive device is operated under load (with a lighted arc), the primary magnetic flux F 1 (Fig. 1), created by the current flowing through the primary winding of the welding transformer, partially dissipates, passing a certain length of the path outside the magnetic circuit. As a result, the magnetic flux Ф 2 (Fig. 1), penetrating the secondary winding, becomes less than the primary flux Ф 1 by the magnitude of the scattering flux Фσ. Thus, the cross section of the magnetic circuit in the region of the secondary winding can be reduced in proportion to the decrease in the magnitude of the magnetic flux, gradually increasing the cross section as it approaches the primary winding. For this number of screws and the cross-sectional area of the magnetic circuit of the welding transformer in the primary winding region is calculated on the mains voltage, and the cross-sectional area of the magnetic circuit in the secondary winding region is calculated on the arc voltage, reduced to the number of turns of the primary winding, at the rated current of the welding transformer.

 As a result of using a magnetic circuit with a variable cross section in the inventive device, it is possible to achieve uniform use of the magnetic circuit cross section. Moreover, the magnitude of the maximum magnetic induction at any point of the magnetic circuit during its operation under load remains approximately the same, corresponding to the unsaturated state of the magnetic circuit. The consequence of this is a significant decrease in comparison with the prototype losses in steel (magnetic core material). However, this does not lead to an increase in the mass of the magnetic circuit of the claimed device.

 In the particular case, the effect obtained when creating the prototype [1], can be used in conjunction with the inventive device. In this case, the cross section of the magnetic circuit in the primary winding region and the number of turns of the primary winding of the welding transformer are calculated on the part of the mains voltage equal to the geometric voltage difference; mains voltage minus the half-difference of the mains voltage and reduced to the number of turns of the primary voltage winding in the arc gap. The cross section of the magnetic circuit in the secondary region is calculated on the voltage on the arc gap, reduced to the number of turns of the primary winding.

 In this case, you can achieve even better than the prototype mass-dimensional, and accordingly cost, indicators (A / K 2 mass of the device).

 However, a reduction in steel losses will not occur.

 The operation of the claimed device is similar to the description of the prototype. The illustrations given in the description of the prototype are also true for the claimed device.

A comparison of the proposed technical solution with the prototype allows you to establish compliance with its criterion of "novelty", because the device has new features:
The welding transformer has a magnetic core of variable cross section. Its cross section and the number of turns of the primary winding are designed for mains voltage, and in the area of the secondary winding only for voltage in the arc gap during arc burning.

 The cross section of the magnetic circuit gradually increases from the region of the secondary winding to the region of the primary winding.

 Comparison of the claimed solution not only with the prototype, but also with other technical solutions in the art did not allow to identify a welding transformer having a combination of a variable cross section of the magnetic circuit, a thyristor control circuit in the primary circuit and a capacitor in the secondary circuit.

 This allows us to conclude that the technical solution meets the criterion of "inventive step".

In FIG. 1 shows a simplified magnetic circuit where:
F 1 - magnetic flux generated by the current of the primary winding of the transformer.

 F 2 - magnetic flux penetrating the secondary winding of the welding transformer.

 φ σ is the magnetic flux of scattering.

In FIG. 2 shows a simplified electrical diagram of a device where:
1. Thyristors
2. Thyristor control circuit
3. Transformer
4. Capacitor
5. Arc gap
In FIG. 3 shows an example of a welding transformer with a magnetic core of variable cross section, where:
1. The primary winding of the transformer
2. Transformer secondary
3. The magnetic core of variable cross section
Technical implementation
The possibility of using a magnetic core of variable cross section was tested on a specially converted transformer of the TDM 401 type.

The cross section of its magnetic circuit was reduced as shown in FIG. 3 in the secondary region from 64 cm ² to 24 cm ² . The transformer connection diagram is shown in FIG. 2. The circuit used T-142-80 thyristors and a capacitor of type MBG4-1 4 μF 500 V. The circuit automatically excludes the XX device mode.

 When working under load (welding), the value of the maximum magnetic induction measured in any part of the magnetic circuit did not exceed 1.8 T.

 The mass of the magnetic circuit of the device is reduced by 30% compared with the serial magnetic circuit of the TDM 401 transformer.

Sources of information
1. RU 2032506, B 23 K 9/00, 04/10/95.

Claims (1)

 A welding device comprising a welding transformer, counter-parallel thyristors in the circuit of its primary winding, a thyristor control circuit and a capacitor connected in parallel with the secondary winding, characterized in that the transformer magnetic circuit is made with a variable smoothly varying cross section, with a maximum cross section located in the primary winding region , and the minimum - in the field of the secondary winding.

Images