ИССЛЕДОВАНИЕ ТВЕРДОГО ТОЧЕНИЯ СТАЛИ ХВГ

Abstract

The paper presents the results of the experiment on the processing of 105WCr6 steel ring blanks prehardened up to the HRC 55 hardness. This material is applied to produce cutting and measuring tools with the high requirements for the accuracy in size and flatness after the thermal treatment. The experiment involved the ring facing using the 16B16T1C1 machine with the CBN plate cutter without the use of a lubricating and cooling fluid. The cutting rate and the advancement and depth of cutting were varied during the three-factor experiment. For the wider industrial application, hard turning requires the additional research related to the study of special aspects of chip formation, the identification of the dependencies of cutting forces and temperature in the cutting zone on the processing mode. The authors studied the chip formation process and the quality of processed surface and carried out the systematization of chip types depending on the cutting modes. The main technology factor determining a chip type is the cutting rate. When it increases the chip type changes from a continuous chip through a transition form to a segmental chip. When zooming in a chip, the welldefined chip segmentation can be seen. When increasing the cutting rate the segments become more defined that causes the change of a chip type. At the critical value of the cutting rate, the chip comes from a discontinuous one to a segmental chip. In this case, the dynamic component of cutting force related to the chip formation process grows. Such change in the cutting process dynamics is accompanied by the corresponding traces of a tool on a processed surface. Stable type of chip formation promotes the formation of a surface with the regular minimum height microrelief. The growth of chip formation dynamism, when increasing the cutting rate, causes the formation of a moire effect on a processed surface. The study identified the processing modes optimal in terms of efficiency, surface condition and chip type. The results obtained can be used to organize an automated manufacturing with the use of CNC machines and automatic lines.