Reasons for the fracture of mandrel of stainless steel cold rolling mill and its elimination

Points to note about broken mandrels. First of all, the mold will wear during the rolling process. Usually the service life of the pass is dozens of times the mandrel, so when the pass is rolled for tens of tons, it will be worn. If the same is not used When the mandrel produced by the manufacturer does not match the deformation curve, it will cause uneven distribution of the deformation area in severe cases. The reduction of the wall is too concentrated, so that a certain part of the mandrel is particularly concentrated. When the stress on a certain part of the mandrel When the accumulation reaches a certain level, all the core rods will be broken. Once this situation is dealt with: 1 Ensure that the mold is matched. 2 If the quality of the mandrel’s supplier’s product is determined, Zhai will carefully check the hole pattern. Use the wear of each point of the regular hole pattern to determine the outer circle processing amount of the hole pattern. If a certain part of the hole pattern is found to be worn More concentrated 1 It means that the front section of the corresponding part of the new rod is insufficiently compressed. (or the outer circle of the core rod is small) resulting in a concentrated amount of deformation. Therefore, when grinding, you must carefully consider whether to change the core rod or to change the hole shape. In short To do so, try not to cause wear concentration. Second, the core constant fracture is caused by other factors: 1 the position of the core rod is improper during the adjustment, 2 the delivery is too large as possible 3 the inner wall of the tube blank 4 the heat treatment of the tube blank extension direction is uneven, resulting in interest calculation Excessive performance deviation 5 Poor lubrication of the inner wall of the billet 5 Straw steel on the surface of the mandrel 7 Serious wear of the mandrel, etc.