Application of the energy-static method for determining the forces and torques acting on the tool when two-roll helical piercing with drive guide wheels

Determining the forces and moments acting on the working tool of the piercing mill is an urgent task in the context of the ongoing intensification of the piercing process on two-roll cross rolling mills. This work is devoted to the improvement and discovery of the energy-static method provisions for determining the integral characteristics of metal forming processes. This method was first formulated and further developed by Vydrin Vladimir Nikolaevich in his writings, as applied to the piercing process on two-roll cross rolling mills with guiding drive wheels. A system of equations for determining the normal pressure on the rolls, mandrel and guide drive wheels of a two-roll helical piercing mill, at each half-step of the axial feed of the workpiece is obtained according to the provisions of the energy-static method. The equations included in the system are obtained by taking into account the geometric features of the deformation zone (distortion caused by the complex geometry of the working tool and the rotation of the rolls at the feed and rolling angles) and the kinematic features of the process. The analysis of possible options for vector diagrams of velocity of points on the contact surfaces of the metal with guide drive wheels, depending on the nature of the possible slip zones was treated in this work. The results of this analysis were used to take into account the deviation of the specific friction forces from the axial direction on the contact surfaces of the metal with the wheels. It is noted that for mills where a scheme with a freely rotating mandrel is used, additional conditions must be used to resolve the resulting system of equations. The use of dependencies to determine the contact pressure on the rolls with screw piercing is given as an example.