FR2498506A1 - METHOD AND DEVICE FOR COMPRESSION-ENDED ELECTRICAL WELDING AND SOLDER THUS OBTAINED - Google Patents

Abstract

THE INVENTION CONCERNS A PROCESS AND A DEVICE FOR ELECTRIC BUTT WELDING BY COMPRESSION OF PARTS WITH A LARGE EXTENT OF WELDING CROSS-SECTION. THE INVENTION CONSISTS OF PRECEDING THE PROPER WELDING PROGRAM (HEATING AND DISCHARGE) BY A CONTACT PROGRAM FOR OBTAINING A UNIFORM CONTACT ON THE ENTIRE WELDING CROSS-SECTION SURFACE. THE INVENTION IS APPLICABLE TO THE WELDING OF SHEETS OR TUBES, IN PARTICULAR BY APPROXIMATION, SPARKLING OR PURE RESISTANCE.

Description

The present invention relates generally and essentially to

  subject of a process of electrical welding end-to-end compression, especially by spark or pure resistance, in particular large-scale pieces of work or extension of cross-section welding, for example sheets or tubes, as well as a device for carrying out this process and the welded industrial products thus obtained. The invention

  also relates to the various applications and uses

  resulting from the implementation of such a process or device and to systems, apparatus, machines,

  equipment and installations provided with such devices.

  It is in fact mainly welding of pieces of work whose cross sectional shape differs greatly from that of a circle or a square with a perimeter or a minimum periphery with respect to the surface or area, that is to say which have large external dimensions, with a surface or area of equal cross section. In electrical end-to-end welding by compression, in particular by flashing or pure resistance, the sheet ends, to be welded together, shall be heated by passing through the electrical current to the welding temperature and then soldered

  together by mutual pressing against each other. The condition

  Beforehand, for butt-compression welding, is the uniform heating of the two workpiece ends over the entire welding cross-section. This is where the problem itself lies. In addition, the heating must be carried out so quickly that on the front surfaces does not form any oxide or scale that would then remain in the weld seam or the welded joint during mutual compression or discharge. Only very little oxide or calamine is forced out of compression

  weld or welded seam during backflow.

  To achieve even heating, uniform contact resistance across the entire welding cross-section and even distribution of electrical current are required. Uniform contact is not achieved because of the always existing unevenness, roughness or roughness of cross-sectional surfaces mutually abutting against each other. One possibility of obtaining a uniform contact of mutually abutting cross-sectional surfaces against each other is to heat the unevenness, unevenness or roughness of the surfaces to be welded together by traversing electric current to the state p and then spread them in width by crushing or pressing, so that a uniform contact of the two

  cross section to weld together be realized.

  Then the heating and the mutual compression or the displacement of the workpieces against each other, that is to say the welding operation proper, would then take place. This method, however, also does not lead to a satisfactory result, as has been found in the

of the present invention.

  In fact, the initially protruding asperities, which are then spread in width, in the pasty state, by compression or crushing, then already have a temperature so high that, during the subsequent heating over the entire

  weld cross section, these locations achieve

  save the welding temperature substantially earlier than the remaining locations. Uniform heating is not

so not got.

  The invention is based on the task of proposing a method, by which the mentioned drawbacks are avoided and an impeccable welding end-to-end by

  compression is achieved by simple means.

  The solution to this problem is to precede the actual welding program, consisting of heating and repression, with a separate or separate contact program to obtain a

  uniform contact across the entire cross-sectional area

Versale welding.

  Thanks to the time separation of the contact program preparing the welding, of the subsequent or consecutive welding program, one avoids on the one hand excessive pressure forces during spreading in width by compression or crushing of the asperities and, of on the other hand, uneven temperatures in the process of

welding proper.

  According to a further development of the invention, the contact program consists of a large contact force and a high intensity of electric current, whereby asperities in the contact plane are heated and spread in width by compression or crushing. The contact program is then terminated by a short period of cooling and equalization or heat equalization without electrical current. In this way, we obtain a

  uniform contact over the entire cross-sectional area

  solder and a uniform initial temperature as well as a uniform contact resistance for the

subsequent welding.

  Finally according to the invention, for the execution of the method according to the invention, the pieces of work to be welded together must be mounted tight or recessed for a very short time or very

  short between two well-cooled electrodes.

  The invention makes it possible to maintain the contact program for a time so short that the risk of

  Oxide or scale formation is avoided.

  For this purpose, the two ends, for example of a circle or tire locking ring on rim, are mounted tight or recessed in two clamping devices, mutually opposite or arranged opposite, a welding machine-butt end-to-end, respectively comprising a water-cooled electrode and a

clamping jaw.

  One of the clamping devices is mounted on a carriage which is driven in such a way that the tine edges are pressed against each other according to a previously chosen program of force. At one of the electrodes is brought the electric current may be previously selected and returning through the edges of the sheet and the other electrode to the source of electric current. In order to be largely independent of external influences and to obtain a uniformly reproducible welding temperature, another development of the process according to the invention consists in that the end of the heating, within the actual welding program, is given by the course of a space, path or adjustable path, in which case the path or path is, for a given contact force, a measure of the

welding temperature.

  This can also be obtained by another development of the process according to the invention, which is

  characterized in that the end of the warm-up, within

  of the actual welding program, is given by obtaining a quadratic quantity of

  electrical (I2t) given in advance.

  The welding process according to the invention thus comprises: 1. Period of contact: During this period, a uniform contact is produced over the entire width of the sheet by heating and spreading

  in width by compression or crushing of the asperities.

  2. Cooling period: During this period a cooling

  dissipating or removing non-uniform or irregular heat

  from the contact period.

  3. Heating and discharge period During this period, the sheet edges are uniformly fed to the discharge temperature and discharged

across the width.

  It was only the cooling period that brought success,

Claims (5)

R E V E N D I C A T I 0 N S   1.- A method of compression end-to-end electric welding, in particular of large-scale welding cross-section pieces, for example sheets or tubes, characterized in that the actual welding program ( heating and repression) is preceded by a contact program to obtain uniform contact over the entire   welding cross-sectional area.   2. Method according to claim 1, characterized in that, during the contact program, asperities in the contact plane are heated and spread in width by compression or crushing by means of a large contact force and a high intensity of electric current and in that the contact program is completed by a short period of cooling and heat equalization or equalization without electric current. 3. A process according to claim 1, characterized in that the end of the heating, inside the welding program itself, is given by the course of an adjustable path or path, in which case the path or path is, for a force of   given contact, a measurement of the welding temperature.   4. A process according to claim 1, characterized in that the end of the heating, within the actual welding program, is given by obtaining a quadratic amount of electric current (12t) given in advance.   5.- Device for carrying out the method according to claim 1 or 2, characterized in that the parts to be welded together are embedded or clamped for a very short time or very short between well-cooled electrodes, 6 Welded industrial product, characterized in that it is obtained by the method according to at least one of the Claims 1 to 4.