The vibration resistance of the dynamic system of a cutting machine is considered as a criterion for assessing its dynamic quality and limiting capabilities. An example of diagnosing a group of machines of the same type by the criterion of vibration resistance with an assessment of their current state is given.
At parts manufacturing using metal-cutting machine tools, the process conditions eliminating high vibration levels are among the most important factors ensuring safe operation of the said metal-cutting machine tools. To solve the task, specific features typical for creation of the dynamic model of mechanical processing in the space of condition variables at contact interaction in the cutting zone based on the piecewise linear approximation were discussed. The contact interaction process was considered as the double-phase one envisaging sequence of retention at adhesion and sliding at adhesion bonds rupture. The cutting tool’ and the workpiece’ contact interactions are presented in the form of rheological models. Conditions of retention and sliding phases sequence are formed by the system itself that is the self-excited one. The set of research performed allowed considering contact interaction of the machined surface with the rear surface of the tool and the of the moving chip with the anterior surface of the tool with the anterior surface of the tool as factors largely defining the conditions of self-sustained oscillations. The contact interaction’ double-phase nature ensures self-organised dosing and selectiveness of the dynamic contours at interaction in the autonomous dynamic process system.
At manufacture of heavy-duty parts, one of the important factors ensuring their safety operation is directional formation of technological residual stresses, nature of distribution of the latter having direct effect on the reliability indices. Concept of the deforming ability of the technological residual stresses was formulated as the moment load intensity adjusted to the surface. The method was proposed for calculation of torques from the effect of the technological residual stresses’ deforming ability as applicable to discrete models of parts with thin-walled elements at turning. Methodical specifics of the computation scheme formation for elastic after-effect of the technological residual stresses’ deforming ability at machining were discussed. Variants of schematization for standard elements of the parts were presented. Pre-requisites were formed for solving the task of controlling residual deformations of parts with thin-walled elements at turning.
The set of studies on modified superficial layer friction pair parts made of X155CrVMo12-1steel was discussed. The said layer is produced according to the duplex process of nitriding and oxidation and is investigated using methods of metallography, X-ray diffraction analysis and micro-hardness measurement based on the oblique and transverse polished sections of the studied surfaces. The results produced proved the duplex process efficiency.
The paper suggests a technique to determine thermophysical properties of heat-resistant steels and alloys in machining. The method of sources serves the basis for the technique. Three heat sources are considered: primary chipping zone, contact area between a tool face and chipping, contact area between a tool clearance and a detail. The results on heating of the processed material are received.
Keywords-heat-resistant steels and alloys; machining; thermophysical properties; temperature; method of sources• for chipping -two-dimensional, banded source limited by two coordinate axes, evenly distributed, fast-moving within an established process, core, Newmann's boundary condition.
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