SU893447A1 - Method of plasma-arc welding by consumable electrode - Google Patents

Description

(54) METHOD OF PLASMA-ARC WELDING BY MELTING ELECTRODE

I

The invention relates to welding production, in particular, to methods of arc welding, and can be used primarily for the automatic welding of long welds.

Plasma-arc welding with an IJ electrode electrode is known.

Known methods of plasma-arc welding with a melting electrode do not provide the stability of the joint burning of plasma and arc discharges under the action of perturbations leading to a change in the length of the plasma or arc discharges.

There is a method of plasma welding with a fusion electrode in an inert gas environment. The method consists in that the burning of the arc discharge between the electrode wire fed at a constant speed to the welding zone and the product is carried out in an ionized gas medium formed by a direct discharge plasma discharge column 2.

The disadvantage of this method is the insufficient stability of the joint burning of the plasma and arc bits. It is that under the action of certain

perturbations (changes in the distance between the plasma torch and the product), change in the arc discharge voltage between the welding wire and the product, change in the wire feed speed, electrode wear

5 nodes of the plasma torch, etc.) there is a change in the depth of the axial immersion of the wire in the plasma. With an increase in the depth of the axial immersion of the wire into the plasma above a certain value, the plasma discharge between the electrode assembly of the plasma torch and

10, the product extinguishes and an arc discharge occurs between the electrode assembly and the welding wire. Thus, the stability of the joint burning of the plasma and arc discharges is impaired. The transition of the plasma discharge from the product to the welding wire 5 according to the principle of the minimum of Steenbek occurs when the voltage drop in the plasma discharge column, at the wire immersion section in the plasma, is sufficient to form active spots on the wire, this can be done express the ratio of the following values:

Claims (2)

Elnorp. and. where E is the potential gradient in the plasma discharge column B / cm; L is the depth of the axial immersion of the wire in the plasma, cm ;. and the voltage required to form active spots on the wire, V; 1 /, - reverse polarity of plasma and arc discharges; 0 — polarity of plasma and arc discharges; - lack of arc discharge; 1 / (V / 0. - cathode and anode voltage drop on the wire, B. The aim of the invention is to increase the stability of the joint burning of the plasma and arc discharges. The goal is achieved by the fact that the depth of the melting electrode in the plasma is set in the range :,,, ... a, 5U / E: Lnorp. / C, where k, is the voltage required to form an active spot, a melting electrode. B; C, -. potential gradient in a plasma discharge column. yes, V / cm; f-bubble immersing melting,: from the electrode into the plasma, see. between the melting electrode and the product, using a power source, excites a plasma discharge, along the axis of which, through a conductive tip, a melting electrode is fed into the welding zone and with a power source, excites an arc discharge. to the point of its entry into the plasma, is the immersion depth of the electrode in the plasma Example: Welding in argon in reverse polarity using 8 mm thick samples of steel 3 and melting electrode of the brand St. 08 G2S, in the following modes: current at plasma 200 A; arc current 300 A; welding speed 100 m / h; gas consumption 8 s / min; wire diameter 1.2 mm; 40 mm melting electrode reach; nozzle diameter 12 mm; anode diameter of 8 mm; The depth of the electrode in the plasma is 12 mm. With an increase in the immersion depth of the melting electrode into the plasma of more than 15 mm, the plasma discharge from the product to the wire occurs. The use of the proposed method will improve the stability of the joint combustion of the plasma and arc discharges, and, consequently, improve the quality and productivity of welding. The invention of the method of plasma-arc welding with a melting electrode, in which the arc discharge occurs in an ionized gas environment formed by a plasma discharge of direct action, characterized in that, in order to increase the stability of the joint plasma and arc discharges, the axial depth immersion of the melting electrode in the plasma is set in the range of 0.5U / E Lnorp, U / Ej where and is the voltage required to form active spots on the melting electrode. AT; E is the potential gradient in the plasma discharge column. V / cm; i-norp. the depth of the melting electrode in the plasma, see. Sources of information taken into account in the examination 1. UK Patent No. 1490479, cl. 23 K 9/16, 1977. 2. The patent of France No. 2132345, cl. 23 K 9/00, 1972.