Grinding is divided into dry grinding and wet grinding, which is also an obvious feature that distinguishes cast steel balls from forged steel balls.
When the mill is running, repairing or replacing the liner, all the steel balls in the mill need to be poured out. This requires attention to the change of the steel ball temperature, especially the combined steel ball.
If the temperature of the running steel ball drops significantly (or use a lot of water injection),
Surface peeling will occur. Peel and even crush directly.
Why should forged steel balls be tempered?
1. As far as the performance of the steel ball is concerned, when the temperature of the forged and rolled steel ball after quenching is lower than 30°C (it can be taken directly by hand), internal stress has been generated, causing many problems in the use of the steel ball. Only by quickly reheating the quenched steel ball to the tempering temperature range and eliminating internal stress can the entire production process be successfully completed and the crushing rate reduced;
2. Quick tempering measures: the tempering temperature control range is 180-200 degrees (plus or minus 20 degrees), and the steel balls of special specifications and materials undergo special treatment;
3. Factors causing pressure: iron basket, iron bucket, ground, vertical air, etc.
The two important points are:
1. If the residual temperature tempering method is used, after the steel ball is quenched, the tempering temperature cannot be too low, not lower than 40 degrees;
Second, when the tempered steel balls are put into the warehouse, the temperature of the steel balls poured into the warehouse should not be too high, and should not be higher than 120-140 degrees. The high and low are two important nodes. Tempering should be carried out when the temperature rises, and the time in the furnace should be extended. It is necessary to ensure that the steel ball wears back (for example, 4 hours in normal, 6 hours in low temperature); when the storage temperature is high, stress will occur again, causing the above-mentioned crushing phenomenon.