Centrifugal casting and inoculation method of roll outer layer

Abstract

The invention discloses a thick working layer roller outer layer centrifugal casting and molding method. Variable-speed casting is adopted in the method, and the whole outer layer is changed from simultaneous solidification to layer-by-layer solidification. The specific casting method comprises the steps that molten iron of the whole outer layer is subjected to continuous casting in sequence according to the rapid-slow-rapid mode, 20% of the total amount of molten iron is cast at first, and the casting speed is controlled to be 5+ / -0.5 t / min; the casting speed is decreased, 50% of the total amount of molten iron is cast, and the casting speed is controlled to be 2+ / -0.5 t / min; the speed is increased, 30% of the total amount of molten iron is cast, and the casting speed is controlled to be 7+ / -0.5 t / min; an outer layer molding agent is added in the centrifugal casting process, and the adding amount is 0.5% of the total weight of molten iron. The whole outer layer is cast at different casting speeds, the defects of slag inclusion and looseness caused by low temperature of molten iron in the later casting period are eliminated, the composition segregation problem caused by long time of solidification in a mold is eliminated, the molding time is shortened, the molding inoculation fade phenomenon is eliminated, and the outer layer is good in hardness uniformity.

Description

technical field [0001] The invention belongs to the technical field of pressure roll manufacturing, and in particular relates to a centrifugal casting and inoculation method for the outer layer of a roll. Background technique [0002] Due to its excellent accident resistance, good wear resistance and surface quality, high-nickel-chromium infinitely chilled cast iron rolls are currently the mainstream rolls in the finishing mills of hot-strip tandem rolling mills, especially the finished rolling mills, and high-speed steel rolls are not yet available. replace. Generally speaking, the thickness of the outer layer of the high-nickel-chromium infinitely chilled cast iron roll is 40mm, and in order to ensure that the roll can be used normally until it is scrapped, and to avoid the problem of fatigue spalling in the later period of use, the roll manufacturer usually increases the support by 10mm The outer layer is designed according to the thickness of the outer layer of ≥50mm, b...

AI Technical Summary

Problems solved by technology

As the thickness of the outer layer increases, the amount of molten iron in the outer layer increases accordingly. If the casting speed is kept constant, the casting time will be prolonged, and the temperature of the molten iron in the later stage of casting will be too low, which is not good for feeding and scum

If the casting speed is increased, the casting temperature will be higher, and the solidification time in the mold will be prolonged, which is not conducive to solidification layer by layer, and may cause composition segregation

Therefore, after the amount of molten iron in the outer layer increases, regardless of the prolongation of the casting time or the prolongation of the solidification time in the mold, it will cause a long inoculation time, inoculation decline, affect the shape and quantity of graphite, and then affect the performance of the product.