DETERMINATION OF THE CALCULATED HEIGHT OF ROUGHNESS COMBS WHEN PROCESSING THE PROFILE OF PARTS BY THE ENVELOPING METHOD

Abstract

The paper presents the results of studies of the nature of the formation of roughness ridges on a surface machined with a multi-blade tool by the enveloping method. It is indicated that the height of the actual irregularities consists of the height determined by the profile of the cutting edges of the tool, the feed and can be calculated, and some increase that depends on the processes of plastic deformation in the cutting zone, friction on the contact surfaces and other factors. Studies by various authors have established that at cutting speeds greater than 2 m/s the profile of the actual irregularities differs little from the calculated ones. The problem of determining the latter is especially complicated when machining surfaces by the enveloping method due to the great variety of shapes of the cutting edges and the complex kinematics of such processes. The paper proposes to determine the height of the irregularities as the sum of their components in the plane of the generating cutting surface and the guide. Despite the different shapes of the cutting edges, due to the small feed per cutting cycle at the contact points that form the roughness profile, this profile can be represented as formed by arcs of circles, the curvature of which is equal to the curvature of the cutting edge and the nominal cutting surface in the contact area. In the case of straight cutting edges or the nominal surface of the part, it is assumed that the radius of curvature is equal to infinity. Formulas of dependencies describing different shapes of cutting edges and nominal surfaces of the part are obtained, and recommendations for their use in various processing methods are also given. The error from the use of these dependencies does not exceed several percent, which is acceptable for technological calculations.