Influence of the parameters of deforming cutting on the features of the resulting slotted filter structures

Abstract

Introduction. Slot filters are in demand in petrochemical, machine-building, food, mining and other industries. DC is an edge cutting machining method based on undercutting and plastic deformation of the workpiece’s surface layer without its removal in the form of chip. DC stands out from the other slot structure forming methods for its capability of obtaining fine filters (slot width upwards of 20 µm) while maintaining relatively high productivity rate and being waste-free. Nevertheless, patterns of through slots cutting by means of DC had virtually not been investigated previously. The purpose of the work is to establish the influence of the main parameters of deformational cutting, namely feed and depth of cut, on features of through slots obtained, as well as identifying combinations of parameters that ensure the production of structures suitable for filtration. Method of investigation consisted of experiments on through-cutting of corrugations stamped on copper strips and a visual analysis of the structures obtained. Cutting through the corrugations by DC was conducted on a lathe while using a special attachment – a barrel which workpiece corrugated strips were wrapped around and fixed on with tension. Results and discussion. The resulting typical structures obtained under different combinations of depth of cut and feed are systemized and divided into the following groups: “0” – the absence of the through cut; “1” – uniform slots; “2” – “twinning” (pairwise convergence of slot walls), “3” – stripping of every second slot wall; “4” – non-regular or complete stripping of slot walls; “5” – uniform slots with a continuous burr (“skirt”) formed along the slot row on the internal side of the corrugation; “6” – uniform slots with a “skirt” opened incompletely. In the range of feeds 0.2 ... 0.4 mm/rev with increasing cutting depth, there is a transition from structures of group “1” to structures of group “2”, and the greater the feed, the greater the maximum depth of cut, at which uniform slots remain. Group “1” is assigned to the area of structures suitable for filtration applications, although it is characterized by the formation of individual burrs on the inner side of each slot. At lower feeds (up to 0.2 mm/rev) with further increase of the depth of cut another group of structures potentially suitable for filtering purposes is reached: groups “5” and “6”. With the “skirt” formed, individual burrs next to each slots are absent, and the shape of slots is cleaner. With a decrease in feed, the width of the resulting slots decreases. The least tool feed value, at which uniform slots are obtained, is 0.05 mm/rev which corresponds to 19 µm slot width. Establishing the causes of “twinning” and the formation of “skirts” requires further investigation.