Experimental research of the frictional condition in the pipes extrusion process

Abstract

The article demonstrated the results of an experimental study of the pipe extrusion process using the method of coordinate grids. The estimation of the influence of separate conditions of friction on the contact surfaces of the deformable material and the pressing tool on metal flow pattern. The calculation of the forming operation is made for extrusion process stages. It is shown that the deformation proceeds non-uniformly. At the same time, due to the creation of favorable conditions on the contact surfaces with the use of the lubricant, the deformable sample differs uniformly in the distribution of the coordinate grid along the wall thickness of the tube’s sample. The boundary stagnation zones are identifying. It has been demonstrated that the front portion of the sample tubes is not fully worked through the wall thickness. While, the rear section is characterized by a dense grid structure. This in combination allows us to indirectly judge the possible anisotropy of the properties along the body of extruded pipes. It is proved that the using of lubricants on the contact surface: the press needle – inner surface of the sleeve will not have a significant effect on the extrusion force, and can be used mainly to ensure the durability of the press tool and to perform the quality characteristics of the inner surface of the extruded tubes. It was concluded that, first of all, the requirements for thermo-technical properties: heat capacity and thermal conductivity, and, secondarily, frictional, must be imposed on lubricants used for coating the inner surface of the sleeve and, accordingly, providing a separation layer between the press needle and the sleeve.