JPH05112815A - Method for treating surface flaw by vacuum arc electric discharge - Google Patents

Abstract

PURPOSE:To reduce the amt. of trimming and to improve the yield by detecting flaws on the surface of the material to be treated which is continuously fed, regulating the electric discharge mode of a divided unit electrode to set value and subjecting it to electric discharge machining. CONSTITUTION:A vacuum treating chamber 30 held to a vacuum of 1 to 10<-3> Torr is oppositely equipped with electrodes 9 and conductor rolls 6 one after the other with the pass line of the strip 20 interposed. As for the electrodes 9, largely divided electrodes are arranged in a row in the breadwise direction of the strip 20, and the unit electrode is each provided with an electric discharge mode selectively. Furthermore, the electrodes 9 are provided in multistage rows in the breadwise direction of the strip 20. While the strip 20 is passed through, the flaws of the sheet are detected, e.g., by a noncontact flow detector 32, and the electric discharge mode of the unit electrode directly above or directly below the flaw parts among the electrodes 9 is previously regulated to set value by a controller 33. Then, oxides encroached on the defect parts are evaporated away by an electric discharge arc, and after that, crater parts removed by the electric discharge mode of the other unit electrode is fused, by which it is made smooth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating surface defects by vacuum arc discharge.

[0002]

2. Description of the Related Art In high-grade steel such as stainless steel and high-strength steel, wrinkles appearing to be caused by uneven elongation near the edges during rolling, and oxides are embedded in the wrinkles, which are very difficult to remove. Becomes In addition, the surface of the plate may be damaged, but in the conventional technique, after the shot blasting treatment, the acid still remains after the treatment with nitric acid, hydrofluoric acid, sulfuric acid, hydrochloric acid, etc. The method was to remove it to make it harmless, or to trim the edge of the edge and measure it. This is very costly and has a large yield loss.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a method for treating surface flaws by vacuum arc discharge with high yield.

[0004]

The gist of the present invention is 1-10.
-The material to be processed is continuously fed in a vacuum of ^-3 Torr, multiple electrodes are provided in the width direction of the material to be processed, and the electrodes are provided in multiple rows in the length direction of the material to be processed. A surface flaw treatment method by vacuum arc discharge characterized by detecting a flaw and inputting a discharge mode selected by calculation or the like to a unit electrode at the flaw position to perform flaw machining.

The present invention removes surface flaws of a material to be treated (hereinafter referred to as a strip) such as ferrous or non-ferrous metal, but it is 1 to 10 ^-3 Torr.
The metal oxide on the surface of the strip is removed by an arc discharge between the strip and the electrodes in a vacuum.

[0006] In a vacuum discharge arc, discharge starts from the place where there is a squelch (metal oxide), and when the scale is removed by a shocking evaporation action and a metal surface appears, the arc does not fly to the metal surface and the work function The discharge moves to the small scale part.

In atmospheric pressure discharge or underwater discharge, only one bright spot (arc pot) can be formed on the cathode and the anode, but in vacuum, a large number of very small arc pots are generated on the cathode, and these are violently and randomly moving. The descaling is done rapidly.

That is, according to the present invention, the oxide which has penetrated into the flaws on the surface is evaporated and removed by the arc discharge between the electrodes in a vacuum of 1 to 10 ^-3 Torr. It is divided into multiple directions so that the discharge mode of the unit electrode can be changed by remote control.

In the discharge mode, the current, voltage, magnetic field strength, and direction are stored in advance in the control system, and information on the property of the flaw, particularly the depth of the flaw is obtained and calculated by the control system to determine an appropriate discharge mode. It shall be selected and input to the unit electrode directly above or below the flaw.

The present invention will be described below with reference to the drawings. In FIGS. 1 and 2, the vacuum processing chamber 30 is provided with vacuum adjusting chambers 31 and 31 on the inlet side and the outlet side, and is constantly maintained at a vacuum of 1-30 ⁻³ Torr. In the vacuum processing chamber 30, the electrodes 9 and the conductor rolls 6 are placed opposite to each other with the strip pass line interposed therebetween, and the electrode-conductor rolls are alternately arranged.

The electrodes 9 are multi-divided electrodes arranged in a row in the width direction of the strip, and each unit electrode is selectively given a discharge mode. Each unit electrode of the divided electrode 9 is electrically connected to a control system including a controller 33 and a calculator 34.

Further, the present invention is provided downstream of the payoff reel 21.
A detector 32 is provided on the pass line of the strip, and the detection information is input to the control system. A non-contact flaw detector is used as the detector and is not particularly limited.

Therefore, according to the present invention, the flaw of the board is detected while passing the strip 20 from the pay-off reel 21.
The controller 33 changes the discharge mode of the unit electrode of the electrode 9 directly above or below the plate defect. The discharge mode is a value preset for each material and can be input to the unit electrode based on a command from a computer.

That is, the oxide in which the scratches are hard to evaporate is removed by the discharge arc, and then the crater parts removed by the discharge mode of the unit electrodes in the rear row are melted and fused.

FIG. 3 schematically shows a strip defect, but the scale 21 of the strip 20 is evaporated into a recess 22 by the electric discharge machining of the present invention. The concave portion 22 is further melted and smoothed by selecting the discharge mode. Similarly, the seam flaw 23 forms the concave portion 22 by electric discharge machining, but is smoothed by selecting the electric discharge mode.

[0016]

EXAMPLE An example of edge processing of martensite 13Cr stainless steel having a plate width of 15 mm is shown below. Vacuum degree 10 ^-2
The discharge mode of the main electrode is 25V × 5 in the Torr vacuum chamber.
00A, the discharge mode of the auxiliary electrode was set to 27V × 400A.

The feed rate of the strip was 20 mpm, and a photocell was provided as a flaw detector. FIG. 4 is a photograph showing the result of the edge flaw processing, but complete scale removal was obtained.

[0018]

According to the present invention, since the selected discharge mode is input to the divided unit electrodes and the detected flaws of the strip are subjected to the electric discharge machining, the trimming amount is reduced and the yield is improved.

Further, since the treatment is performed by electricity, it is possible to treat the material of any material without selecting the kind of the acid and changing the concentration thereof depending on the object to be treated, which has an effect of eliminating the treatment by the acid and eliminating pollution.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the present invention.

FIG. 2 is an enlarged view of a main part of the present invention.

FIG. 3 (a) is an explanatory view of a flaw on a material to be treated, and FIG.
[Fig. 3] is an enlarged view of a seam defect of a strip.

FIG. 4 is a photograph of a scale removing unit.

[Explanation of symbols]

 6 Conductor roll 9 Electrode 20 Strip 30 Vacuum processing chamber

Claims (1)

[Claims] 1. A material to be treated is continuously fed in a vacuum of 1 to 10 ⁻³ Torr, a plurality of electrodes are provided in the width direction of the material to be treated, and a plurality of rows are arranged in the length direction of the material to be treated. A surface flaw treatment method by vacuum arc discharge, characterized in that a surface flaw of a material to be treated is detected, and a discharge mode selected by calculation or the like is input to a unit electrode at the flaw position to perform flaw machining.