ANALYSIS AND SELECTION OF RATIONAL CUTTING MODES WHILE USING HARD-ALLOY TOOL FOR SHAFT TURNING

Turning machining of such parts as shafts is considered as the most widely-spread method formanufacturing units, mechanisms and machinery. While doing so it is necessary to ensure high quality of shaft turning with the help of a hard-alloy tool (accuracy and roughness, stability and predictability of steel edge dimensional wear), maximum tool durability, resource of its service life and productivity. As it is known all these operational parameters of the tool depend very heavily on cutting speed. However absence of an analytical dependence for determination of optimum cutting speed value does not per permit to prescribe optimum operational modes at the stage of technology design process. The cutting tool can be subjected to mechanical, anrasive, adhesive, oxidation (chemical), thermal-fatigue and diffusion wear types depending on turning conditions. In this case wearing process consists of two wear types and one of them influences at a certain point on wearing process to a greater extent than the other one. Methodology for prescription of rational turning modes for medium and high cutting speeds ensuring maximum resource of the tool operation has been developed in the paper and it has been based on the analysis of the existing viewpoints about changes in the hard-alloy tool durability due to cutting speed while turning shafts. The range of cutting speed changes has been determined in the paper and it leads to an increase of the tool durability period and, correspondingly, turning productivity of 45 steel grade shafts while using the tool with T15K6-hard-alloy replaceable inserts