JPS5992116A - Descaling method of hot rolled band steel - Google Patents

Abstract

PURPOSE:To remove and clean a blasting agent remaining on th surface of a band steel by removing scales on the surface of a hot rolled band steel by projecting a blasting agent and then injecting high-pressure water of specified condition. CONSTITUTION:A hot rolled band steel 2 coiled after hot rolling is rewound from the coil 1, and a blasting agent such as steel shots, steel grids, etc. made to a slurry form by high-pressure water is projected onto the surface of the band steel by a descaling device 3 to remove scales on the surface of the hot rolled band steel 1. Then, the high pressure water 4 having pressure shown in the inequally (1) is injected to remove the blasting agent intruded into the surface of the band steel and improve the property of the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for removing oxidized scale from a hot-rolled steel strip by applying slurry-like polishing to the surface of the steel strip at high pressure. This invention relates to a method for descaling a hot rolled steel strip, characterized in that the remaining 1k of Kiken 4TL material that has bitten into the surface of the copper strip is removed by spraying.

Oxidized scale is formed on the surface of a copper strip rolled in a hot rolling mill during the rolling, winding, and subsequent cooling periods. Although there are some applications in which hot-rolled steel strip is used without removing scale, the majority of hot-rolled steel strip is usually subjected to descaling treatment.

Conventionally, as a technology to remove oxide scale on the surface of copper strips,
A method of chemically removing scale by continuously passing a copper strip through an acid solution such as hydrochloric acid or sulfuric acid was generally used, but the time required for descaling was long and work efficiency was low. Therefore, there was a problem of low productivity. In order to eliminate these disadvantages of the conventional method, in recent years, a slurry-like abrasive material made by mixing iron sand, steel shot, steel grid, etc. with high-pressure water is projected onto the surface of the copper strip to remove oxidized scale. A method of removing it is being implemented.

However, in order to efficiently and completely remove the liquefied scale using this method, the slurry projection pressure must be increased, and as a result, the abrasive material may bite into the surface of the copper strip and remain, degrading the surface quality of the final product. There was.

The present invention has been made in order to solve the problems associated with the descaling process caused by the abrasive material i described in . In other words, during the process after hot rolling and before winding, or during descaling treatment while unwinding a hot rolled steel strip that has been hot rolled and wound into a coil, high pressure water under certain conditions is used after the abrasive is projected. 1. Preventing the abrasive from remaining on the surface of the copper strip by spraying it on the surface of the steel iPr.
71 targets.

An embodiment of the present invention will be explained with reference to FIG. While unwinding the coil l wound up after hot rolling, oxidation scale is removed from the surface of the steel strip 2 using an abrasive jetting type descaling device 3, and subsequently, high pressure water 4 is sprayed onto the surface of the copper strip.

FIG. 2 is a side view of the main parts of the water injection section. The distance #H (mm) between the injection nozzle and the steel strip surface shown in Fig. 2, the high pressure water injection angle (the angle between the high pressure injection water and a line perpendicular to the steel plate surface) α (
Tests were conducted by varying the injection water pressure P (kg/cm') and the surface residue of Ti, AM, Si, etc.
! The relationship between t and the removal rate was investigated, and the results shown in the third column were obtained.

In FIG. 3, Pa defined by the F formula is plotted on the horizontal axis.

Pa = (9,53cosct -0,0059H-
1, 33) Angle) (1m) H: Distance between the injection nozzle and the surface of the copper strip M (mm) P: Pressure of the injection water (kg/
cm'). Also, the vertical axis in Figure 3 is (Wo - W) /Wo X 100 (%).
・・・・・・・・・・・・ (2) Indicates where Wo: Surface residue when high-pressure water is not injected W: Indicates the amount of surface residue when high-pressure water is injected. , Wo, and W are all obtained from the X-ray analysis numbers.

The following is clear from Figure 3.

When Pa≧0.6, 60% or more of the surface residue 1^ is removed. When Pa<0.6, surface residue removal is extremely poor.

Next, test pieces were taken from the coils with Pa<0.6 and Pa≧0.6, and tin-plated. As a result, Pa
<0.6, a large number of pinhole defects were observed on the surface of the Menki plate, and iron was leached ((i (I, S).

(2) There are two problems with "High Practicality", but there were no problems with the test pieces with Pa≧0.6.

[Brief explanation of the drawing]

Figure 1 is a process diagram conceptually showing the implementation of the method of the present invention;
The figure is a side view of the main part of the high-pressure water injection part, and FIG. 3 is a graph showing an example of the removal rate of surface residual liquid by the method of the present invention. l...Hot rolled coil, 2... Steel strip. 3... Descaling treatment device using abrasive material. 4... High pressure water injection device special 1 product applicant Kawasaki Steel Corporation

Claims (1)

[Claims] l Hot J1 = In a descaling method in which an abrasive material is projected onto the surface of a rolled steel gauge, following the abrasive material projection, high-pressure water that satisfies the following formula is applied to the surface of the copper strip. A method for descaling a hot rolled steel strip, the method comprising spraying. (9,53cos α-0, OO59H -1,33) XPX 10-3 ≧0. Niconi α: High-pressure water injection angle (angle between high-pressure injection water and a line perpendicular to the surface of the copper strip) (degrees) H: Distance between the injection nozzle and the surface of the copper strip (mm) P: Pressure of the injection water ( kg/cm')