Roller mills are mills that use cylindrical rollers, either in opposing pairs or against flat plates, to crush or grind various materials, such as grain, ore, gravel, plastic, and others. Roller grain mills are an alternative to traditional millstone arrangements in gristmills. Roller mills for rock complement other types of mills, such as ball mills and hammermills, in such industries as the mining and processing of ore and construction aggregate; cement milling; and recycling.
Qiming Machinery has been producing rolling mill wear components for steel mills for over 20 years. Our experience combined with the full service of a vertically integrated manufacturing facility leads to high quality, long-lasting parts. Engineering, pattern making, foundry work, machining, and quality assurance. We’re a trusted source for finished castings used in industrial manufacturing. Every part is guaranteed for proper fit, performance and customer satisfaction.
Recently, we get an order from our customer about high chromium roll mill liners:
- Name: Roll Mill Liners
- Weight: 19 tons
- Sizes: 4501*3900*1090 mm
- Material: High Chromium Steel
- Hardness: More than 58 HRC
Roll Mill Liners Material Choice
The main idea of chemical composition design is: Increase the carbon content to obtain a sufficient amount of high hardness eutectic carbide. However, the carbon content is too high, the carbides form a network and the brittleness is increased; The chromium content is appropriate to ensure that the matrix structure is mainly martensite after quenching, thereby ensuring sufficient hardness. Combined with our company’s Cr26 material experiment, the determined composition is shown in the following:
Roll Mill Liners Casting Process Design
Molded with alkaline phenolic resin sand. The casting size exceeds 4500mm. Considering the limitations of tooling and site conditions, it is decided to use the entire core and outer cavity process scheme.
The maximum direction length of this roll mill liner is more than 4000mm. Considering that the linear shrinkage of high-chromium cast iron is difficult to calculate accurately and is the current status of core production, refer to the casting size tolerance and machining allowance (GB / T6414-1999), and the upper-end machining amount is left. 25mm, the machining volume of the lower end surface is 20mm.
Take the method of parting from the middle parting.
According to the solidification characteristics of high chromium anti-wear white cast iron, the sequential solidification principle is adopted. A top riser is set at the highest part of the sheath, and a side riser is not easy to place the top riser. The wall thickness of the casting is 120mm, and it is determined as a riser neck 140mm according to the proportional method. There are 11 risers with a diameter of 350mm and a height of 800mm.
The weight of the part is 19t, and the pouring weight of the pouring riser is about 28t. According to the pouring weight, the diameter of the perforation hole is determined to be 70mm. Select the F-perforation: F straight: F horizontal: F inside = 1: 1.5 ~ 2: 1 ~ 1.5: 2 ~ 4 closed and open type pouring system. According to the specifications of the ceramic runner brick, it is determined that the straight runner is 90mm, the horizontal runner is 70mm, and the inner runner is 50mm. Finally, it was determined that F resistance = F envelope hole = F horizontal = 3846 mm2, F straight = 6359 mm2, and F inside = 11775 mm2. F envelope hole: F straight: F horizontal: inside F = 1: 1.65: 1: 3.
Pouring temperature and speed
According to the characteristics of this alloy, the casting temperature is determined to be 1360 ~ 1410 ℃ in combination with the casting structure and on-site pouring conditions; the pouring speed is 4 ~ 5min.
Alkaline phenolic resin sand molding, the draft angle of the model is 1.5 °, the casting shrinkage rate is 2%, and the pouring temperature is 1380 ~ 1400 ° C.
The production of two pieces was carried out according to the established process. After the casting was boxed and cleaned, it was found to have a good appearance, no obvious shrinkage and shrinkage in the feeder, and magnetic particle inspection, indicating that the internal structure of the casting was dense and free of defects. The dimensional measurement is also satisfactory. The hardness after heat treatment is 58-60HRC. The customer is satisfied with the quality of the casting after inspection.