SU865472A1 - Method of detecting weld while cold-rolling strips - Google Patents

Description

I

The invention relates to metallurgy and, in turn, to sheet-rolling production, and can be used for the timely deceleration of a mill when passing a section of a strip with a welded seam.

A known method for detecting a weld is based on the fact that the weld zone of the coil joints has a greater hardness compared to the base metal and differs from the base metal in magnetic properties 11.

However, this method is applicable only to ferromagnetic steel grades.

There is also known a method of contact indication of a weld in cold rolling mills, which implies that labels are applied to the strip with a fast-drying lacquer, which are then read using contact electrode 2.

However, in this method, false positives of the sensor are possible due to the presence of defects on the strip, inadequately pickled areas, the label is destroyed when the turns in the roll are compacted at the beginning of rolling.

A well-known method of weld indication, I concludes with the fact that a mark in the form of a round hole (with a diameter up to 5 mm at a distance from the edge of the strip up to 10 mm) is used to detect the weld, which is read by means of a photo-sequential device 3).

The disadvantage of this method is that the hole, being a stress concentrator, can lead to disruption of the metal continuity in the area between the hole and the edge, which creates an additional danger of strip breakage in this area.

The purpose of the invention is to increase the reliability of the weld by reducing the concentration of stresses in the heat-affected zone.

This goal is achieved in that according to the method of detecting a weld, including drawing through marks (perforations) on the edge of a strip and detecting them with a photo-subsequent tool, the marks are applied in the form of semicircular cuts, which are located on either side of the weld.

The advantage of the proposed method is that the semicircular cuts do not create additional danger, and on the contrary, reduce the effect of the concentration of tensile stresses in the area between the cuts, thereby increasing the reliability of the welded

UIBOB.

The drawing shows a strip with paired semicircular cuts.

The cut-outs are produced directly in the welding machines or in a separate installation after the operation for producing the weld.

 Example. Testing of the proposed method was carried out on a steel strip 2.5 mm thick, 500 mm wide. The semicircular cuts were made on an industrial plant in the line and continuous pickling of strips of the shop M 2 of the Novolipetsk Metallurgical Plant. The radius of the cutouts (R) is 25 mm; the distance between the centers of the cutouts (o) is 65 mm. A light bulb with a directional beam was used as the illuminator. The light flux during the passage of the cut-outs was registered using 2 FD-5 photodiodes set 65 mm apart from the Friend, i.e. at the center of the cutouts.

The electrical circuit provides for the presence of an electrical signal on the recording device in the case of simultaneous exposure of two photodiodes.

The proposed method provides high reliability of the seam with its high-quality display. The object of the invention may be rolling mills and other units of continuous action in the production of any steel grades.

Claims (3)

1. Referativny magazine Metallurgi, 1976, N 4, 4 D 328. 2. USSR author's certificate number 250087, cl. B 21 C 51/00, 1966. 3.Lifshits L.A. Abstract of Ph.D. theses. Dnipropetrovsk, 1973, p. 18.