Research of the rolled stock separating into workpieces using breaking by bending with dynamic and static-dynamic force

The work aims to improve the quality of workpieces obtained by breaking rolled stock products by researching the separation process under dynamic and static-dynamic loading on a press-hammer. Combined static-dynamic loading during cold breaking by bending allows to reduce of high-frequency vibrations of the “tool-specimen-support” system, to eliminate the violation of the contact of the specimen with the supports, and to reduce the peak values of the forces from the side of a punch and supports. The static force at the moment of impact provides a certain initial level of tensile stresses in the area of the stress concentrator. This has a positive effect on the quality of the obtained workpieces. The magnitude of the static force required to exclude the separation of the specimen from the supports depends on the stiffness of the contact between the head and the intermediate punch and increases with increasing this stiffness. The obtained experimental results confirm the adequacy of the mathematical model of specimen separation by the breaking method under dynamic and static-dynamic loading. It has been experimentally established that the value of the preliminary static force must be at least 40% of the force at which the specimen is broken down. Obtained results can be used to improve the technology of separating rolled stock into dimensional workpieces by the method of cold breaking by bending.