SU1486299A2 - Method of high-frequency welding - Google Patents

Description

The invention relates to high-frequency butt welding and can find application in the metallurgical, automotive and other industries. The purpose of the invention is the simplification of welding equipment,

expansion of technological capabilities and improvement of the quality of welded joints at the end sections. High-frequency butt-welding involves heating the edges with a high-frequency current flowing through them, at which the ends of the edges alternately cut and part. A current is applied to each edge at one of two points symmetrically located with respect to the center of the edge. The distance between these points is not less than two diameters of the current-carrying contacts. The point of the current supply is changed synchronously with the dilution of the ends of the edges, moving it towards the diluted ends. The method allows to increase the width of the welded blanks with a significant decrease in the applied voltage. 4 il.

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The invention relates to a technique of welding, in particular to methods of welding with heating the edges of high-frequency currents, can be used in the metallurgical, automotive and other industries and is an improvement of the invention according to the author. No. 980972.

The purpose of the invention is to simplify the welding equipment, expand its technological capabilities and improve the quality of welded joints at the endpoints.

The essence of the invention is that high-frequency butt welding, including heating the edges of the workpiece flowing through them in opposite directions of current

The high frequency at which, in the process of heating, the end sections of the edges are alternately reduced and separated by rotary oscillations imparted to the workpiece, followed by a draft of the edges, is carried out in synchronization with the dilution of the end sections by moving the current supply to the edges of the blank. To do this, choose two places for the supply of current, located symmetrically relative to the middle of the edges, and set the distance between them is not less than two diameters of current-carrying contacts. When breeding the end sections, the current supply is moved to the side of these sections. As a result, in each period of time circuit

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the ends of the edges perform heating of the edges, exceeding half of their length. The heating of the edges between the places of the current supply is carried out continuously, therefore, the existing instability of the heating of the contact zone is aligned. The proposed method of high-frequency butt welding allows to almost double the width of the welded workpieces when using the same equipment. And a significant reduction in the magnitude of the voltage supplied to the edges of the high frequency current. The choice of the initial gap between the edges and the implementation of the closure of the end sections when current is supplied alternately to different points ensures uniform heating of the edges of the workpiece along the entire length.

FIG. 1 and 2 shows a diagram of the implementation of the welding method when feeding the edges of welded blanks from one welding transformer; in fig. 3rd 4th scheme of the method for powering two transformers.

The welding circuit contains a high-frequency generator 1 connected to the resonant capacitor 2 and the primary winding of the welding transformer 3. The secondary winding of the transformer is connected to the welded blanks 4 through the current-carrying contacts 5,

The edges are powered in the same way when two welding transformers are used (Figs. 3 and 4), the operation mode of each of which is controlled by thyristor contacts 6. At the same time, the transformers are connected to heated blanks by pairs of current-carrying contacts 7 and 8, respectively.

Welding when powering the edges from one transformer is as follows.

The blanks 4 are placed in centering clamping devices, which are provided with a drive of oncoming movement to change the size of the gap between the edges of the blanks and the implementation of precipitation. In the initial position, the current-carrying contacts 5 connected to the transformer 3 are pressed against the blanks in their middle part. Then make the closure

the end portion, while the current-carrying contacts 5 are moved to the point M (figure 1). When voltage is applied to the transformer 3, the welding current flows along the part of the edges placed between the points M through the closed end section. The part of the edges outside the closed circuit.

Ιθ is not exposed to heating, and the zone in which current-carrying contacts are located is heated less stably and intensively to the place where the current is completely displaced to the edges. Then carry out the closure of the opposite end portion (figure 2), while moving the current-carrying contacts 5 to point N. The process of heating the edges proceeds

2 £, similarly to that described, Since the heating is not carried out simultaneously over the entire length of the edges with the same value of the secondary voltage, the width of the welded blanks may be larger than in the case of simultaneous heating,

. The distance between points M and N should be greater than the size of the zone of unstable heating at the current-carrying contacts, this value is equal to two diameters of the contacts.

Appropriate choice of the gap between the edges to be welded, the frequency of change in the position of the current leads and shorting edges of the edges

35 ensures their uniform heating over the entire length. After melting the surface layer of the edges by selecting the total time of their heating in the process of cyclically shifting 40 "

sashchayusya closure and opening carry out the draft of the workpiece.

'When using as a power source for the edges with a welding current of two transformers for heating a part of the edges placed between the current-receiving contacts 7 and 8 and flashing the end sections when they close, it is necessary to connect the primary windings of the transformers to the output terminals of the generator in accordance with the synchronous opening of the ends of the conductive edges . The switching of the primary windings of the transformers is carried out by two thyristor contactors 6, assembled in an anti-parallel scheme. As a contact device for supplying high frequency current can be used5

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Copper segments provided with a drive for rolling them along the surface of welded blanks. In this case, in the initial position, the edges are in the open state, the current leads are shifted towards the end sections, and the welding transformers are switched on according to the sequential scheme. When voltage is applied to

transformers 3 current flows along the edges of the workpieces 4 between the current-carrying contacts 7 and 8. Simultaneously with the command to close one of the end sections of the current-to-water, water moves to the middle part of the workpieces 4, and the transformers switch to counter-parallel operation or disagree with them by reducing voltage on the transformer closest to the closure end section. The cycles are repeated until the edges of the welded blanks are melted, and then they are precipitated by the instantaneous application of 25 compressive force, providing ’

counter-deformation of melted edges.

Experimental studies 39

for high-frequency butt welding was performed on a laboratory setup with an electromagnetic welding drive. Installation provided with pneumatically operated pre ezha- ment _35, power transformer TK-2-800, capacitances ESP-O, 8, control of the welding mode settings, providing complete control to the time-1OO possibility RVD pulsed welding current switching.

As a power source, two electric machine generators of 100 kW each, connected in parallel, were used. The frequency of the supply voltage is 8 kHz. The maximum force developed by electromagnets, 10 tons, the heating time on the installation was changed within 0.02-4 s.

Experiments have shown that for blanks with a thickness of 5 mm and a width of 250 mm with a gap between the edges of 2 mm, the welding time is 2.0 s with a power consumption of 170 kW. Taking into account the time spent on the installation of blanks, the total time of manufacture of the welded product is about 4-5 s.

Claims (2)

Claim Method of high-frequency butt welding on auth.St. No. 980972, characterized in that, in order to simplify welding equipment, expand technological capabilities and improve the quality of welded joints at the end sections, a high-frequency current is supplied to each of the welded edges with current-conducting contacts alternately at one of two points located symmetrically with respect to the middle edge at the distance from one another is not less than two diameters of the current-carrying contacts; the point of current supply is changed synchronously with the dilution of one of the ends of the edges and the mixing of the others, moving it all First time in the direction of divorced ends. '2 / 1486299 fi & .З fi & .b-