What are the material characteristics of cast iron roll?

Aiming at the problems of difficult processing and low processing power of cast iron roll, this paper expounds the characteristics of cast iron roll, tool raw materials, machine tool function, processing technology and application, and clarifies the influence of tool selection, processing technology, machine tool requirements and roll application on the use of cast iron roll.

　　1. Cast iron roll

High-carbon high-speed steel composite roll (referred to as cast iron roll) is the rapid development in recent years and the use of a wide range of hot roll materials, its composition is more complex alloy steel, in the heat treatment process after quenching, even in the air cooling can be hardened. The working layer material is made of high carbon steel, and the core material of the roll is made of ductile iron, graphite steel or forged steel. The two different materials are compounded by centrifugal casting or CPC process. The matrix arrangement is generally tempered martensite bainite carbide, which is scattered in the matrix in a highly dispersed form, so it has high wear resistance and strong resistance, resulting in difficult turning processing.

2. Selection of tool raw materials

The cutting part of the tool is directly in contact with the roll, receiving a lot of cutting pressure and impact, and under high temperature and high pressure, it has a violent conflict with the roll, and the working conditions are very bad. The processing tools of cast iron rolls are generally made of superhard materials such as diamond and cubic boron nitride (CBN for nitride), and their cutting speed is 10 to 20 times higher than that of general carbide tools, and the value of surface roughness is very small. The CBN raw material tool has higher hardness, thermal stability and chemical laziness than diamond, as well as excellent functions such as excellent red appearance and wide band gap.

(1) high hardness. Cubic boron nitride (CBN) is second only to diamond, with high hardness and wear resistance, is the steel rolling enterprise cast iron roll processing tool raw material selection. At present, the composition type of CBN tool has two kinds: polycrystalline wafer (composed of CBN and binder) and composite sheet (composed of CBN and binder on cemented carbide sheet).

(2) Satisfy the strength and resistance. Tool cutting part of the raw material in the cutting process to receive a large cutting force and impact. Therefore, it must have satisfactory strength and resistance. Polycrystalline diamond (PCD) has two types of natural and artificial, industrial use of artificial diamond as a tool material. But artificial diamond brittleness, impact resistance is poor, the accuracy of the machine, the stability of the high requirements, with poor heat resistance of diamond tools, and iron has a strong affinity, and thus the diamond tool is primarily used for non-ferrous metals and their alloy materials processing, not applicable to the processing of ferrous metals, it is generally not used for roll processing. The CBN tool thermal stability is twice as high as diamond, with excellent chemical stability, bending strength and fracture resistance between cemented carbide and ceramic tools, suitable for processing steel materials.

(3) High wear resistance and heat resistance. Generally speaking, the higher the hardness of the tool material, the better the wear resistance. Wear resistance is closely related to heat resistance. The higher the hardness at high temperature, the better the heat resistance. CBN raw material tool can adhere to high hardness at high temperature, that is, good red hardness. Together at high temperatures, the ability to resist plastic deformation is strong, so the wear resistance is also high.

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