RESEARCH OF THE MICROHARDNESS OF THE SURFACE OF A CYLINDRICAL PART DURING DEFORMATION

Abstract

It is known that when processing plastic materials by cutting, chip grinding is a serious problem. The formation of a stable, strong draining chip is a sign of low machinability of the material of the part and requires the use of special means and methods that would ensure the separation of the chip or allowance that is cut. This issue is especially relevant in the case of cutting drawing as a low-speed process, which is characterized by intensive overgrowth and a high coefficient of chip shrinkage, and therefore the strength of the latter. Today, there are a number of original developments of several scientific schools, which implement the idea of preliminary division of the allowance during drawing by creating a network of technological chip-splitting grooves. The process of internal drawing, in particular drawing of round deep holes, must necessarily take place under conditions of forced chip separation or allowance. At the same time, the so-called transverse division of the chips, i.e., division along the perimeter of the hole, is usually carried out due to structural elements on the broach teeth and today is not too difficult a problem. However, there are certain reserves in this direction as well, in particular those related to increasing the stability of the tool. This article considered the technological function of the reliefs, which consists in the forced division of the cut allowance with contour grooves. An analysis of the advantages and disadvantages of the most common processes for obtaining round holes in hollow blanks and parts is carried out. The essence of the group (progressive, variable) stretching scheme is described. Typical combined extension tools are considered. Given formulas for calculating the dimensions of chip grooves. The first component р of the change in the diameter of the hole and the outer diameter of the workpiece after each of the combined drawing operations is characterized.