A Casting Process for Periodical Pipe Mill Rolls

Abstract

The invention discloses a casting process for rolls of a periodic pipe rolling mill, which comprises the following steps: ① Installing a mold; ② Hanging 15-25mm high-temperature-resistant molding sand in the pass of the mold, firming the molding sand, and scraping out the roll hole After drying in the shade for 24-48 hours, paint the paint formulated with 2-3mm zirconium silver powder, and then dry it in the furnace; ③, prepare the chemical composition for the molten iron, and obtain the roll blank after pouring; ④, rough-process the roll blank, Then carry out high-temperature heat treatment; ⑤, slice the end face of the lower roll neck of the rough roll after heat treatment for tensile and impact tests, and verify the tensile strength and section rolling toughness of the roll; Perform flaw detection and metallographic testing, and finally finish the roll and pass. The forging toughness, wear resistance, thermal crack resistance and other comprehensive properties of the cast roll of the invention are all significantly improved.

Description

technical field [0001] The invention relates to a casting process for rolls of a periodic pipe rolling mill. Background technique [0002] The periodic pipe rolling mill is a seamless steel pipe rolling mill with the largest outer diameter of 660mm and the thickest pipe wall. The biggest feature of rolling seamless steel pipes by this machine is that the deformation of each pass in the elongation and rolling of steel pipes is concentrated in the same stage. Finished in the rolling groove. Therefore, the roll pass used in the pipe rolling mill is in the middle of the roll body, and the pass is sag. The hole pattern is a complex variable section curve, the maximum and minimum ratio of the hole pattern is about 2, which is similar to a crankshaft. Therefore, the requirements for the roll not only have high strength, forging toughness, wear resistance and thermal crack resistance. In addition, due to the non-concentricity of the roll pass, the widest and deepest sag hole proc...

AI Technical Summary

Problems solved by technology

In addition, due to the non-concentricity of the roll pass, the widest and deepest sag hole processed by a flat roll is close to the center of the roll. Due to the slow solidification and crystallization conditions of molten steel, part of the matrix structure grains are not refined and there are loose areas. Therefore, the rolling life is relatively poor, and small steel fiber pimples are prone to appear in the inner arc of the pass during forging and rolling operations, which will directly affect the quality of the outer circle of the steel pipe and the rolling output

At present, most of the rolls used in periodic pipe rolling mills are made of AS60Ⅰ. Because of their low carbon content and low alloy content, the rolls have low hardness, poor forging toughness, wear resistance, and thermal crack resistance.