COMPLEX PARAMETER OF DURABILITY OF SUPPORT PLATES OF CUTTING ELEMENTS OF BLOCK-MODULAR CUTTERS

The author considered the issues of working capacity improvement of multi-element cutting tools (in terms of such operational characteristics as, for example, the intensity of breakdowns of cutting element and its support plates, etc.) by changing the regulation of status parameters of a surface layer of their parts. The weakness and low reliability of cutters prove the necessity in the elements with the defined properties within the cutting tools structure. The shape of the cutting element supporting surface influences the specified properties of cutting tool parts. The author considered the shape of a profile of cutting element supporting surface in the form of two irregularities located at a distance of waviness step (in the form of oil pockets). The profile shape is considered as a stress concentrator. According to the decrease in the concentrator durability period, the study determined which parameters influence the durability. Cutting element reacts to the cutting force load and transmits it to other parts of a cutting tool through its base and fastening nodes. The author calculated the surface status complex which includes the achievement of life duration with the dominating influence of height and step roughness and waviness parameters. The calculation is carried out in the base and fastening nodes of a cutting element. In the base nodes, normal stresses dominate on the surface; in the fastening nodes, tangential stresses prevail. It is shown that normal and tangential stresses are equal. The author determined the complex value dependent and independent of the surface treatment conditions (process value and calculated-engineering value respectively). The study indicates how the complex behaves under the loading (breaking-in) of a contact joint as well as how its change influences the working capacity of the multi-element cutter. Block (multi-element) cutters differ from the modular and one-piece cutting tools both by the presence of a large number of elements (30 and more) and by the high contact stresses resulting from their operational conditions. High cutting forces, vibrations (amplitude and vibration frequency of the technological system), wear of elements, low toughness and high suppleness of contact joints are the peculiarities of operational conditions.