Use of Cold Roller2019年08月08日
The cold roll is a complex component with a very hard surface, which bears a great deal of stress. Therefore, the cold roll requires a high manufacturing quality, which is the necessary condition to ensure the use effect.
The service life of cold rolls depends not only on the manufacturing quality, but also on the maintenance in the use process. If used improperly, the use effect will change greatly.
Fatigue spalling is the most common failure form in roll service. It originates from the fatigue crack on the roll surface. If the crack can not be removed completely before it is put on the machine, it will propagate fatigue in the hardened layer, forming a typical fatigue zone, and then produce fatigue spalling. The prevention of such accidents should run through the whole process of roll operation. Users should understand the origin of these cracks and preventive measures.
1. Preservation and Preheating of Rolls
The micro-structure of the roll is very sensitive to sudden temperature change, so it is suggested that the roll should be stored in a suitable temperature environment, padded with sleepers to keep the roll clean.
The roll can not start suddenly under strong load, nor can it stop running suddenly. Reasonable operation is: the roll runs under light load for a period of time, and gradually loads and starts. It is beneficial for the roll to be preheated slightly at a temperature not exceeding 80 C, but the process is slow. It is absolutely forbidden to contact the roll with flame.
Experienced grinders all know that in grinding high hardness rolls, imprudent operations such as sudden feed, large feed, improper selection of grinding wheels will produce grinding cracks, leading to roll spalling.
3. Work hardening
In rolling, the contact fatigue stress on the surface of the roll body causes work hardening, which accumulates continuously and causes cracks. Therefore, regular grinding is needed to remove the fatigue layer.
4. Rolling accidents
Surface cracks of rolls also originate from surface damage caused by rolling accidents, such as skidding, overloading, sticking steel, strip breakage, etc. Therefore, in order to ensure the normal operation of rolling mills, users are advised to establish strict rolling operation rules and equipment rules.
5. Roll Management
Users should establish roll usage files and record roll usage data such as accident, grinding, use stand, rolling quantity, turnover times, roll maintenance, etc. in order to evaluate and feedback to the manufacturer for joint research and improve roll life.