INFLUENCE OF DIE PROFILE ON THE CHARACTER OF STRESS-DEFORMED STATE DURING EXTRUDING OF PIPES
The extrusion is used to obtain hollow profiles in cases where it is impossible to obtain any of the other metal processing methods. As a rule, extrusion in the production of hollow profiles from low-plasticity steel grades with unique performance characteristics. However, even in this case, the quality indicators are reduced in comparison with the extrusion of conventional steels. To improve the quality in the practice of pipe production, various methods are used: changing the temperature regime of heating the workpieces, changing the characteristics of the lubricant involved in the extrusion, changing the size of the workpiece, etc. The development of technologies for the production of pipes using extrusion equipment can be carried out using a package of applied programs for analyzing the stress and strain state, as well as with the known plastometric characteristics of the studied steel grades. Matrices are one of the main technological tools of pipe- extrusion plants, which determine the outer diameter of pipes. Matrices can be of various shapes. In the scientific and technical literature, there is information that the shape of the matrix affects the nature of the stressed and deformed state of the metal when extrusion solid profiles. However, there is no information on the extrusion of hollow profiles. It is assumed that the shape of the matrix during the extrusion of hollow profiles will affect the stressed and deformed state of the metal. Since the shape of the matrix has little effect on the extrusion force, it is possible to change the shape of the matrix in order to increase the ductility of the metal without the threat of exceeding the permissible extrusion force. A computer simulation of the extrusion process from low-plastic grades of steels with different matrix shapes was carried out, according to which their influence on crack formation was analyzed.