JPH0615343A - Method for descaling rolled stock for seamless steel tube - Google Patents

Abstract

PURPOSE:To lower the generation rate of pit flaws without increasing lap flaws by bringing a wire brush into contact with the whole surface n the circumferential direction of the outer peripheral surface while jetting high pressure water on the outer peripheral surface of a rolled stock carried in the axial direction. CONSTITUTION:A high pressure water injection header 3 is provided so that high pressure water can be jetted on the whole surface in the circumferential direction of the outer peripheral surface of a rolled blank 2 for seamless steel tube carried on carrier rollers 1 in an axial direction. The wire brushes 4a, 4b are provided on the front and rear surface of the injection header 3 so that they come into contact with the whole surface in the circumferential direction of the outer peripheral surface of the rolled stock 2 for seamless steel tube. When the scale generated on the rolled stock 2 is descaled first, the scale is removed by wire brush 4a, then, high pressure water is ejected from the injection header 3 to crush the scale finely and the final scale is scraped off with the wire brush 4b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for descaling a seamless rolled steel tube material.

[0002]

2. Description of the Related Art A seamless steel pipe is made by heating a solid material or hollow material having a circular cross section in a heating furnace and punching the heated central portion of the material with a punching machine to form a through hole of a certain size. After that, it is rolled by a rolling mill into a shape close to the product size, and then passed through a shaping machine to be finished into a final product size.

Scale is generated by heating on the outer peripheral surface of a seamless steel tube rolling material heated in a heating furnace. When the seamless steel pipe rolled material is perforated with this scale as it is, the scale bites into the surface of the rolled material, and a recessed hole-shaped flaw called a pit flaw is generated in the final product, which significantly deteriorates the product quality. It will be. Therefore, normally, high-pressure water (for example, high-pressure water of about 150 kg / cm ² ) is sprayed onto the outer peripheral surface of the seamless steel tube rolled material immediately after heating to remove the scale.

[0004]

However, the above-mentioned conventional method for descaling a seamless rolled steel tube material has the following problems. That is, as the pressure of the high-pressure water sprayed is increased, and the volume of the high-pressure water is increased, the scale can be removed more and more. In other words, the occurrence rate of pit defects generated in the seamless steel pipe decreases. However, on the other hand, if the pressure of the high-pressure water is increased or the volume of the high-pressure water is increased, the temperature of the outer peripheral surface of the seamless steel pipe rolling material decreases, making it difficult for the rolling material to move forward by the punching machine, Lap flaws etc. occur.

FIG. 3 is a graph showing how the temperature decrease on the outlet side of the perforator changes with the volume of high pressure water when descaling with high pressure water of 150 kg / cm ² . 1000 liter / min. In contrast, the temperature drop is about 10 ° C, while 3000 liters / mi
n. Shows a temperature drop of about 25 ° C. Therefore, as shown in the graph of the relationship between the volume of high-pressure water and the occurrence rate of flaws in FIG. 4, increasing the volume of high-pressure water decreases the incidence rate of pit flaws but increases lap flaws. There is a problem that the rate of occurrence of defects does not change even if the volume of high pressure water is increased.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and provides a seamless steel pipe rolling material capable of reducing the occurrence rate of pit defects without increasing the number of lap defects. It is intended to provide a descaling method.

[0007]

A method for descaling a seamless rolled steel pipe material according to the present invention is a method for descaling a seamless rolled steel pipe material, which removes scale generated on the outer peripheral surface of the seamless rolled steel pipe material. Then, high-pressure water is sprayed onto the outer peripheral surface of the rolling material being conveyed in the axial direction, and the scale is removed by a wire brush provided so as to contact the entire outer peripheral surface of the rolling material in the circumferential direction.

[0008]

In the method for descaling a seamless rolled steel tube material according to the present invention, when removing the scale generated on the outer peripheral surface of the seamless rolled steel tube material, high-pressure water is sprayed and the outer peripheral surface of the rolled material is circumferentially rotated. The scale is removed with a wire brush that is provided so as to contact the entire surface. This was done by increasing the volume of high-pressure water in order to increase the scale removal rate, because the number of lap marks generated on the outer peripheral surface of the seamless steel pipe rolling material increases, so the volume of high-pressure water should not be increased too much. Instead, it is because it tries to remove it with a wire brush. Therefore, the lap flaw does not increase and the pit flaw decreases, so that the overall occurrence rate of flaws can be reduced.

The wire brush alone cannot be expected to have the effect of finely crushing the scale like high-pressure water, and therefore the scale removal rate cannot be increased. It is also effective to remove the removable scale that is easily peeled off before spraying the high-pressure water.

[0010]

EXAMPLE A descaling method for a seamless rolled steel pipe material according to an embodiment of the present invention will be described with reference to the explanatory view of FIG. In the method for descaling a seamless rolled steel tube material according to one embodiment of the present invention, high-pressure water is applied over the entire circumferential surface of the circumferential surface of the seamless rolled steel tube material 2 that is transported on the transport roller 1 in the axial direction. The high-pressure water jet header 3 is provided so that water can be jetted, and the wire brushes 4a and 4b that are in contact with the front and rear surfaces of the high-pressure water jet header 3 over the entire circumferential surface of the outer peripheral surface of the seamless steel pipe rolling material 2 are provided. It is provided.

When descaling the scale generated in the seamless steel pipe rolling material, first, the wire brush 4a is used.
Then, the scale is dropped, then high-pressure water is sprayed from the high-pressure water jet header 3 to finely crush the scale, and the last remaining scale is scraped off by the wire brush 4b.

FIG. 2 shows that the pressure of the high pressure water is 150 kg / cm.
² , the capacity is 1000 liters / min. It is the graph which arranged how the wire brush contributed to the reduction of the occurrence rate of pit defects. Each of the descaling methods is as shown in Table 1, and it can be seen that a method of spraying high-pressure water and then removing it with a wire brush is particularly effective.

[0013]

[Table 1]

[0014]

According to the present invention, pit defects can be reduced without increasing lap defects.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a descaling method for a seamless rolled steel pipe material according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a descaling method and a pit defect occurrence rate.

FIG. 3 is a graph showing how the amount of temperature decrease on the exit side of the punching machine changes depending on the volume of high-pressure water.

FIG. 4 is a graph showing the relationship between the volume of high-pressure water and the defect occurrence rate.

[Explanation of symbols]

 1 Transport roller 2 Seamless steel pipe rolling material 3 High pressure water jet header 4a Wire brush 4b Wire brush

Claims (1)

[Claims] 1. A method for descaling a seamless rolled steel tube material, which removes scale generated on the outer circumferential surface of the hot rolled seamless steel tube material, wherein high pressure water is applied to the outer circumferential surface of the rolled material being conveyed in the axial direction. A method for descaling a seamless rolled steel pipe material, characterized in that the scale is removed by a wire brush provided so as to make contact with the entire outer circumferential surface of the rolled material in the circumferential direction.