SU1668076A1 - Method of resistance spot welding - Google Patents

Abstract

The invention relates to methods of resistance spot welding of a lead construction element with a steel construction structure with a thickness of up to 6 mm each, mainly for a chemical apparatus. The purpose of the invention is to expand the field of use of the method due to the possibility of welding a lead element with a steel element. Weld surfaces of steel elements are coated with flux or tin. The elements are placed between the electrodes of the welding machine, they are compressed by the welding pressure, the welding current pulses are passed, the welding pressure is reduced to the holding pressure and maintained. Pressure welding and holding, as well as the exposure time regulate. At the same time, the process of welded joint formation is optimized and the depth of the holes on the elements from the electrodes of the welding machine is minimized. 1 il.

Description

The invention relates to resistance welding, in particular, a method of resistance spot welding of a structural element of lead with a structural element of steel with a thickness of 6 mm each, preferably of a chemical apparatus.

The purpose of the invention is to expand the field of use of the method of resistance spot welding due to the possibility of welding a structural element made of lead with a structural element made of steel with a thickness of 6 mm each, mainly of a chemical apparatus, while maintaining the quality of the welded joint.

The drawing shows a sequence diagram of the pressure of welding and holding, as well as the welding current in contact spot welding of a structural element of lead with an element

structures of steel up to 6 mm each, mainly of chemical apparatus.

The essence of the method is as follows: The welded surfaces of the front-sided construction elements of lead with the construction element of steel with a thickness of up to 0 mm each, predominantly of the limiting apparatus, are prepared. In this case, the surface of the element that is being deposited is made from staples in a hole and is filled with a flux or tin. Prepared elements are placed between the electrodes of the machine for fast spot welding. Placed elements are welded. At this, elements are compressed by PI pressure PI, variously 0.15 - 0.20 MPa, a welding current pulse is passed, Pi is reduced to a holding pressure P. equal to 0.05 - 0.10 MPa, and maintained for a time t , different 0,24 - 0 80 s.

ABOUT

oo oo oh

H

about

When using the method in the process of resistance spot welding, the process of formation of the welded joint is optimized and the depth of holes on the welded structural elements from the electrodes of the welding machine is minimized. At the same time, it is possible to weld a structural element of lead with a structural element of steel with a thickness of up to 6 mm each, predominantly of a chemical apparatus, while increasing the strength and corrosion resistance of the welded joint. This extends the field of application of the method while maintaining the quality of the compound.

When the welding pressure is less than 0.15 MPa, lead splashes appear.

With a welding pressure greater than 0.20 MPa and a holding pressure greater than 0.10 MPa, the depth of the insert on the lead element increases and the corrosion resistance of the joint decreases.

With a holding pressure of less than 0.05 MPa and a holding time of less than 0.24 s, the nucleus does not have time to crystallize and the compound spontaneously breaks down.

With a dwell time of more than 0.80 s, the quality of the compound is practically unchanged and the efficiency of the method is reduced.

Contact spot welding of sheets of lead grade C (GOST 3778-77e) and steel grade St. 3Z (GOST 380-71) 4 mm thick each chemical apparatus is performed as follows. The surfaces to be welded are weldable, and the lead is cleaned with a dry metal bar, and the sheet of steel to be welded is cleaned by grinding and covered with a layer of tin 0.01 mm thick with a hot dip. Purified

a sheet of lead and coating sheet of steel placed between the electrodes of the welding machine model MT-3201. Placed sheets pair. Welding modes: pressure

welding 0.18 MPa; welding current pulse density 1360.00 A / mm2; welding current pulse time 0.20 s; holding pressure of 0.08 MPa and shutter speed 0.58s. The welded joints of the sheets are peeled. The test results are positive.

In the process of resistance spot welding, the field of use of the method is expanded due to the possibility of welding a structural element of lead with

structural elements of steel up to 6 mm each, mainly of chemical apparatus, while maintaining the quality of the welded joint. In addition, labor conditions are improved by eliminating

evaporation of lead.

Claims (1)

The invention of the method of resistance spot welding, in which the welded surfaces of the welded structural elements are prepared, the elements are compressed by the welding pressure and pass a welding current pulse, characterized in that, in order to expand the field of application of the method due to the possibility of welding the lead 6 mm each, predominantly of a chemical apparatus, while maintaining the quality of the welded joint, the welded surface of the steel element is coated with a flux or tin, the welding pressure is chosen in the range of 0.15 - 0.20 MPa; after the welding current pulse is applied, the welding pressure is reduced to pressure extracts equal to 0.05 - 0.10 MPA, and incubated for 0.24 - 0.80 s.