JPH0416518B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a flaw prevention agent for seamless steel pipe manufacturing and a flaw prevention method for seamless steel pipes. BACKGROUND ART When manufacturing seamless steel pipes using the Mannesmann method, it is important to prevent the occurrence of show marks. During both the piercer and elongator processes, when billets and shells heated to over 1000°C are deformed, welding occurs between the billets and shells and the shoe that supports them, resulting in marks on the surface of the steel pipe. It is a flaw that occurs. Not only does the shew mark reduce the commercial value of seamless steel pipes, but once it occurs, it cannot be prevented unless the shew mark is replaced. Therefore, the occurrence of show marks causes a significant decrease in productivity. Therefore, in order to prevent the appearance of show marks,
Conventionally, the following method has been adopted. How to pre-grease the shoe. A method of continuously supplying an aqueous graphite dispersion between the shoe and billet and between the shoe and shell during rolling. A method of sprinkling sand on the surface of billets and shells (disclosed in Japanese Patent Publication No. 58-3444). However, in the above method, the grease applied to the shoe begins to burn as soon as it comes into contact with the billet and shell, and disappears within a short period of time, so that a continuous shoe mark prevention effect cannot be obtained. Although this method has an excellent effect of preventing show marks, the aqueous graphite dispersion is inevitably supplied between the rolling roll and the shell during rolling.
Slips occur on the rolling surface, increasing the incidence of defective products and reducing productivity. In addition, in the method described above, the sand is uniformly distributed over the entire surface of the billet and shell, which exerts the effect of preventing shoe marks. Pock-like impressions often occur. Problems to be Solved by the Invention Due to the above-mentioned current situation, it is possible to effectively prevent the occurrence of flaws due to welding between the shoe and billet and between the shoe and shell during the pipe manufacturing process of seamless steel pipes. It is an object of the present invention to provide a method and a flaw prevention agent. Means for Solving the Problems In order to achieve the above object, the present inventors conducted extensive research and found that a specific amount of sand, ferric oxide, silicon oxide, aluminum oxide, etc. with a particle size of 2 mm or less was used. We have discovered that an excellent flaw prevention effect can be obtained by continuously supplying an aqueous dispersion prepared by dispersing water with a thickener between the shoe and the billet and between the shoe and the shell. Completed the invention. That is, the first invention proposed herein is: (a) one or more types selected from the group consisting of sand, ferric oxide, silicon oxide, and aluminum oxide with a particle size of 2 mm or less; 70% by weight, (b) 0.1 to 5% by weight of a thickener, and (c) water. In addition, the second invention proposed herein is a method for manufacturing a seamless steel pipe, in which (a) a material selected from the group consisting of sand, ferric oxide, silicon oxide, and aluminum oxide having a particle size of 2 mm or less; An aqueous dispersion containing 3 to 70% by weight of the seed or two or more, (b) 0.1 to 5% by weight of a thickener, and (c) water is used in both the piercer and elongator processes for the show and billet process. This is a method for preventing flaws in seamless steel pipes, which is characterized by continuously supplying water between the holes and between the shew and the shell. The constituent elements of the present invention will be explained in detail below. (Components of the flaw prevention agent) Component (a) The sand may be mountain sand, sea sand, or river sand, and industrial products can be used for ferric oxide, silicon oxide, and aluminum oxide. These components (a) may be used alone or in combination of two or more. The particle size of component (a) is
2 from the viewpoint of steel pipe product quality and feeding equipment, etc.
It must be less than mm. It is necessary that the proportion of component (a) in the composition is 3 to 70% by weight. If it is less than 3% by weight, the composition will not be effective enough to prevent the show mark, and if it exceeds 70% by weight, the fluidity of the composition will decrease, making it difficult to continuously supply the composition to the show, etc. using a pump. becomes. Thickeners Thickeners are necessary to stably disperse component (a) in the composition, and include carboxymethyl cellulose,
Hydroxyethylcellulose, methylcellulose, sanzan gum, etc. can be used. The proportion of thickener in the composition should be between 0.1 and 5% by weight. Component (a) if less than 0.1% by weight
cannot be stably dispersed in water, and if the amount exceeds 5% by weight, the particle size of the composition becomes too high, making it difficult to supply to a show or the like. Other components In addition to component (a), a thickener, and water as essential components, the flaw prevention agent of the present invention contains other components such as a surfactant and
Addition of alkaline substances, inorganic salts, etc. does not reduce the effects of the present invention, so these can be added as desired. (Method for producing a flaw prevention agent) The flaw prevention agent of the present invention is manufactured as follows. First step: Gradually add a thickener to water and disperse with a homogenizer. Second step Component (a) is added to the composition obtained in the first step and finished by uniformly dispersing it by mechanical stirring. (Supplying method) The method for supplying the scratch preventive agent of the present invention will be explained with reference to the following examples. EXAMPLES Next, the present invention will be specifically explained with reference to Examples and Comparative Examples. However, the present invention is not limited in any way by these Examples and Comparative Examples. FIG. 1 is a plan view schematically showing the implementation state of the flaw prevention method according to the present invention, and FIG. 2 is a front view. A billet is pierced by a roll and a plug using a piercer, but the rolls are located almost symmetrically with respect to the billet's axis on both sides of the billet's movement range, and each rotates at the same speed and in the same direction around the rotation axis. The plug faces the core hole of the billet approximately in the center between the rolls. The billet is regulated by a plug, rolled on both left and right sides by rolls, further regulated by shoes on both upper and lower sides, and rotated around the axis by receiving thrust from the rolls. It is rolled in sequence. Although the shoe is omitted in FIG. 1, it is formed to have the same length or slightly longer than the axial length of the roll, and its width is slightly longer than the distance between the two rolls as shown in FIG. Both of the upper and lower surfaces facing the billet have abutting surfaces having arcuate cross sections along the direction of movement of the billet. During rolling of the billet, the flaw preventing agent is continuously supplied through the nozzle. The nozzle is disposed on the supply side of the billet so as to spray the flaw preventing agent between the shoe and the billet, and sprays the flaw preventing agent in the direction of rolling progress. A supply pipe is connected to the nozzle as shown in FIG. 1, and the nozzle is further connected to a supply pump. The anti-scratch agent can be stored in a tank and continuously supplied to the nozzle by the above-mentioned supply pump. The supply amount and supply pressure of the flaw prevention agent can be adjusted by a regulating valve disposed in the above-mentioned supply piping system. The above describes a method for preventing the occurrence of scratches when a billet is perforated in the piercer process, but the present invention's method for preventing scratches can also be applied when a shell manufactured by the above-mentioned perforation method is processed using an elongator. Any method of supplying the agent is applicable. A seamless steel pipe was rolled while supplying a flaw prevention agent having the composition listed in the upper row of Table 1 between the shoe and the billet and between the shoe and the shell. Table 2 shows the application conditions, and the lower part of Table 1 shows the application results.

【table】

【table】

[Table] Effects of the Invention By continuously supplying the flaw preventive agent for seamless steel pipe production of the present invention between the shoe and the brewet and between the shoe and the shell, shoe marks can be effectively prevented. Moreover, the slip phenomenon during rolling does not occur and pock-like impressions are suppressed, so productivity is significantly improved.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing the implementation state of the flaw prevention method of the present invention, and FIG. 2 is a front view.

Claims (1)

[Claims] 1 (a) Sand, ferric oxide, with a particle size of 2 mm or less;
One or more selected from the group consisting of silicon oxide and aluminum oxide 3-70
% by weight, (b) 0.1 to 5% by weight of a thickener, and (c) water. 2. In the method of manufacturing seamless steel pipes: (a) 3 to 70% by weight of one or more types selected from the group consisting of sand, ferric oxide, silicon oxide, and aluminum oxide with a particle size of 2 mm or less; , (b) an aqueous dispersion containing 0.1 to 5% by weight of a thickener and (c) water is continuously fed between the shoe and billet and between the shoe and shell in both the piercer and elongator steps. A method for preventing flaws in seamless steel pipes.