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The roll is the core part of the mill. The use of the roll involves the selection of the type of the mill, the preparation of the roll, the maintenance and periodic repair in the rolling process, these are all factors that affect the mill productivity, product quality and production economy. As the rolling process is a continuous process, the operator needs to constantly monitor the roll status to make the product meet the user's requirements for more stringent tolerances and surface quality. In order to make products continuously competitive, it is necessary to continuously request mill operators to reduce production costs, that is, to increase rolling speed, mill production flexibility and reduce roll consumption. So roll surfacing welding need to pay attention to what?
(1) the fatigue layer or defects on the surface of the roll body must be removed thoroughly before surfacing welding, especially the cracks;
(2) The roll body must be preheated before surfacing welding in order to prevent the occurrence of cracks, the preheating temperature depends on roller and surfacing material.
(3) in order to obtain the ideal surfacing layer, some variable factors must be taken into account, for example: Welding Voltage, welding speed, roll rotation speed, roll heat preservation, welding current, welding material, etc. . For some roll cores with high carbon and alloy elements, in order to prevent crack in brittle zone, in addition to certain
preheating measures, the low-carbon and low-alloy interlayer is often used for pre-surfacing welding.
(4) Slow Cooling and turning of roller after surfacing welding. In order to reduce the volume stress caused by the difference of cooling rate between surface and interior, the cooling rate should be controlled. Finally, the overlaying roller is machined to its original size and finish.
And the properties of the roll after surfacing welding:
(1) the service life of the roll after surfacing welding is generally increased by more than one time;
(2) the cost of ton steel is greatly reduced and the production effect is improved;
(3) The overlaying roller has good crack resistance, wear resistance and cold and hot fatigue resistance.
