SU1542748A1 - Method of plasma cutting - Google Patents

Abstract

This invention relates to a plasma treatment. The purpose of the invention is to increase cutting performance and avoid double arcing when cutting parts of large cracks. When cutting plasma torch reciprocating move along the cutting line. The arc is compressed by a nozzle with an expanding internal channel. An identical electric potential is supplied to the nozzle and the product, and the plasma torch is introduced into the cutting cavity during reciprocating movement, maintaining a constant distance between its end face and the cutting surface. Compressing the arc by a nozzle with an expanding internal channel allows to obtain a cutting width that lowers the plasma torch into the cutting cavity. 1 il.

Description

(21) 4143430 / 31-27

(22) 11/06/86

(46) 02.15.90. Bul № 6

(71) Special Design Bureau of the Institute of High Temperatures, USSR Academy of Sciences

(72) C. A. Averin, Yu. S. Arbuzov, S. N. Bulger, L. I. Danilov, M.-E.H. Isakayev, Yu. V. Lipukhin, N. O. Spektor, and E. M. Shelkov

(53) 621.791.75 (088.8)

(56) USSR Copyright Certificate No. 366049, cl. 23 K 9/16, 1971.

(54) METHOD OF PLASMA CUTTING

(57) The invention relates to plasma processing. The purpose of the invention is to increase

cutting performance and elimination of double arcing when cutting parts of large thickness. When cutting plasma torch reciprocating move along the cutting line. The arc is compressed by a nozzle with an expanding internal channel. An identical electric potential is supplied to the nozzle and the product, and the plasma torch is introduced into the cutting cavity during reciprocating movement, maintaining a constant distance between its end face and the cutting surface. Compressing the arc by a nozzle with an expanding internal channel allows to obtain a cutting width that lowers the plasma torch into the cutting cavity. 1 il.

The invention relates to the plasma treatment of metals, in particular, to a plasma cutting method, and can be used in plasma cutting by an electric arc in a plasma torch of thick products.

The purpose of the invention is to increase the productivity of plasma cutting of thicker products and the elimination of double arcing.

The drawing schematically shows a device for performing plasma cutting by the proposed method.

The plasma torch has a non-fusible electrode 1 and a nozzle 2 with an expanding internal channel 3. The nozzle 2 and product 4 are connected to the same pole of the power source 5. Thus, they have the same electric potential. A plasma-forming gas is blown through the nozzle 2, the speed of which at the entrance to the expanding internal channel 3 can be about the speed of sound. The nozzle end 6 is set at a distance indicated by

above, and the plasma torch is reported to reciprocate along the cutting line.

The method is carried out as follows.

An electric arc is lit between the nozzle 2 and the electrode 1. Under the influence of the plasma gas flow, the arc from the nozzle 2 transfers to the product 4. The possibility of double arcing is completely excluded.

When the velocity of the cold plasma-forming gas at the entrance to the expanding inner channel of the nozzle, in the order of the speed of sound, the arc burning voltage rises and thus the stability of the arc increases. The firing probability of the arc on the nozzle decreases sharply, and a-1 burning itself cannot destroy the nozzle, since the current is closed by microarcs on a large surface of the internal channel of the nozzle. The same potential between the product and the nozzle completely eliminates the possibility of double arcing.

ate

No.

Ј

00

In the area 7 of the thermal effect of the Electric Arc, the product material melts and the molten metal is carried away by the gas flow. If the width of the forming cut is smaller than the outer diameter of the plasma torch, then by changing the distance between the end face of the nozzle 6 and product 4, the current and flow of the plasma-forming gas increase, so that the plasma torch could rhodit in the cavity of the cut. i Example Made cutting steel. The lazy mode is as follows: arc current 500 A, arc voltage 200 V, plasma gas flow rate kg / s, distance from the end (plasma torch to article 2, m with diameter of the smallest cross section of the internal channel of the nozzle 5, angle between the nozzle axis forming the internal channel nozzle angle between the axis of the nozzle and forming an internal channel of 8 °.

Using the proposed method prevents double arcing completely, as a result of which the resistance of the nozzles increases in two rows. The cutting capacity of products with a thickness of 130 mm is increased by more than 10. A 100 kW plasma torch can cut a product of arbitrary thickness.

Claims (1)

Invention Formula A plasma cutting method in which the arc is compressed with a nozzle, and the plasma torch is moved reciprocally along the cutting line, characterized in that, in order to increase the cutting performance of thick products and to avoid double arcing, the same potential is applied to the product and the nozzle The arc is compressed by a nozzle with an expanding internal channel, and the plasma torch during reciprocating movement is introduced into the cut cavity, maintaining a constant distance between its end face and the cut surface.