Influence of the Shape Error of Measuring Base on the Accuracy of Manufacturing Parts from Stamped Blanks

The article considers the requirement to increase the reliability of functioning of machine parts and mechanisms while maintaining their minimum cost. It is shown that compliance with this requirement is possible if the part blanks are obtained by cold stamping. However, these blanks have significant shape errors and residual stresses. The influence of shape errors of the base surface of a box-shaped part from a stamped blank on the accuracy of manufacturing the part has been studied. It has been proved that large errors in the base surface shape, which are permissible in terms of manufacturing technology and operation, are unacceptable when using such surfaces as measuring bases. To reduce the shape error of an elongated base surface, it is proposed to base the part from a stamped blank during machining and inspection on two sections of this surface that are remote from each other. These sections should have a minimum deviation from flatness, for which they are additionally flattened. The design of the locating fixture-stand for the implementation of the method of basing on selected sections of a stamped surface of increased accuracy is proposed. The feasibility of such a basing method is confirmed by the obtained regression dependencies. The use of the proposed method reduces the shape error of the machined surfaces by an order of magnitude and, accordingly, increases the accuracy of parts manufacturing.