Development and Investigation of Piercing Process Using Cooled Guide Shoes

We consider the problem of wear resistance of guide shoes in the process of piercing in a screw rolling mill. To increase the wear resistance and reduce the adhesion tendency of the metal to the working surface, we propose a new design of guide shoes containing a longitudinal groove on the working surface and the delivery of coolant directly in the process of rolling. The experimental testing of the proposed new design of guide shoes was carried out in the course of rolling of the pipes 194.5 × 15.9 mm in size. After rolling, adhered metal was not detected on the contact surfaces. In order to estimate the deformation of the metal with the use of the new design of guide shoes, we simulated the process of piercing and performed the comparative analysis of the influence of guide shoes of new design upon the parameters of piercing (as compared with the influence of the traditionally applied shoes). It was shown that the deformed metal does not exhibit any tendency to flow into the zone of cooling channels. We also reveal an insignificant increase in the axial speed of piercing, which exerts a positive influence on the weakening of a trend to the formation of internal captivity due to the lower cyclicity of the process. The mean normal force acting upon the guide shoes and the area of contact with the metal decrease by about 20% due to the presence of the groove. As the temperature of the working surfaces of the guide shoes decreases, their wear resistance increases and the quality of the outer surface of the pipes improves.