Influence of the Basing Scheme on the Basing Error as a Component of the Minimum Intermediate Allowance for Machining

Abstract

An important stage in the design of technological processes for machining workpieces of machine parts is to determine the values of the minimum intermediate allowances, on the basis of which the technological dimensions and dimensions of the original workpiece are determined during the subsequent stages.

An effective means of determining intermediate allowances is the computational and analytical method proposed by Professor V. M. Kovan. According to this method, one of the components of the minimum intermediate allowance is the installation error, an important component of which is the positioning error. For the conditions of processing a batch of blanks on a tuned machine, the positioning error, as a component of the minimum allowance, should be determined as the distance between the limiting positions (scattering field) of the surface from which the allowance will be cut, relative to the tool set for the size. With this in mind, we considered and analyzed some common variants of basing schemes for workpieces in machine tools, regarding the presence of a positioning error, as a component of the minimum intermediate allowance for machining main holes in a workpiece of a “Lever” type part, since during the design of technological processes for the manufacture of just this type of parts due to the multivariance of possible basing schemes, certain difficulties arise in determining the basing error as a component of the minimum intermediate allowance. For the considered variants of basing schemes, dependencies were obtained for calculating the magnitude of the basing error.

The results of the work can be used in the design of technological processes of mechanical processing, as well as in the educational process of training specialists in mechanical engineering specialties.