SU1074643A2 - Method of electrocontact heating - Google Patents

Abstract

METHOD OF ELECTROCONTACT HEATING blanks before deforming according to ed. St. 706170, characterized in that, in order to reduce the time for preparation for heating each subsequent batch of billets during intermittent operation, after the end of the heating of the last billet of the previous pair, the contacts in the molten state are closed with a conductive jumper and by heating the first workpiece of the next batch, the contacts are melted by passing an electric current along the jumper, after which the jumper is removed.

Description

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The invention relates to the processing of metals by pressure, in particular to methods for heating billets prior to their deformation.

According to the main author. St. No. 706170, a method is known for electrocontact heating of workpieces before deforming by passing an electric current through the workpiece supplied by metal contacts that are preheated to the melting temperature C.

The disadvantage of this method is a significant loss of time for preparation of each next batch of billets for heating, since after completion of batch heating and deformation the molten metal of the contacts needs to be removed, and before heating the next batch of metal of the contacts it is necessary to melt and re-fill it then proceed directly to the heating of the workpiece before deformation.

The aim of the invention is to reduce the time to prepare for heating.

This goal is achieved by the fact that, according to the method of electrocontact heating of blanks, before deforming, after heating the last blank of the previous batch, the contacts in the molten state are closed with a conductive jumper, and before heating the first blank of the next batch, the contacts melt by passing electric current through jumper, then the jumper is removed.

The presence of a significant transient electrical resistance between the frozen contact material and the jumper on one side and the capacitance on the other hand leads to the release of a large amount of heat and the rapid melting of the contact material.

Example. Two glasses of red copper, connected to the secondary winding of a 50 kW transformer, were filled with molten electrically conductive material (Wood alloy). The ends of a jumper made in the form of a strip of titanium alloy 1 mm thick were placed in the melt.

and in terms of dimensions 10x300 mm, after which the primary winding of a transformer having eight stages of regulation was turned on. To maintain the material of the contacts in a liquid medium, a voltage of 2 V was sufficient (lower control level). After removing the jumper, the ends of the billet were placed in the melt, the voltage was increased to 8 V and heated.

After heating, the billet was removed and the jumper was installed again. The circuit was de-energized and the material of the contacts was cooled before entering the solid phase.

Re-inclusion showed that the melting of the contact material occurred after 10 s and the contacts were completely

0 prepared for work.

Thus, the proposed method of preparation for electrical contact heating allows to increase the reliability of the process, improve the operating conditions and reduce the time to prepare for heating.

The simplicity and reliability of the proposed method consists in the absence of any additional heating devices or other energy sources. A simple and relatively fast method of heating the contacts will save energy by disconnecting devices for heating, rather than keeping the contacts in a heated state, constantly consuming electricity.

Comparative technical and economic

The analysis shows that the advantage of the proposed method with respect to the well-known one will be especially significant under conditions of small-scale production with frequent changes in production objects, and the operational characteristics are improved in the production of products by batches, as well as in the event of forced breaks in work.

Claims (1)

METHOD OF ELECTRIC CONTACT HEATING of workpieces before deformation by ed. St. No. 706170, characterized in that, in order to reduce the time to prepare for each heating. the next batch of workpieces during periodic operation, after the heating of the last billet of the previous batch ends, the contacts in the molten state are closed with a conductive jumper, and before the first billet of the next batch is heated, the contacts are melted by passing electric current through the jumper, after which the jumper is removed.