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

OBRABOTKAMETALLOV Vol. 23 No. 4 2021 TECHNOLOGY Group “4” – non-regular stripping (Fig. 13). As in conventional deforming cutting, at low feed rates in relation to the depth of cut, the process instability is noted, characterized by the breakdown of some or all of the slot walls upon an excess of the ultimate strength of the slot wall material under the action of the DC tool. This group is referred to the area “ D ” on the diagram (Fig. 9) – “reject”. Group “5” – Uniform slots with the formation of a skirt (Fig. 14). With a feed rate of 0.2 mm/rev and less, the following effect was noted: when the tool leaves the material on the inner side of the corrugations, burrs are not formed at each edge separately, but in the form of a single foil tape, bent from the material by the tool and hanging over a row of slots. This tape will be conventionally referred to as “skirt” below. The formation of a skirt may be due to the properties of the surface layer of the material and requires further study. When a skirt is formed, no twinning effects are observed; the slots have a visually uniform width. In addition, upon bending (Fig. 14) and removing the skirt mechanically, a slot structure is found, which is cleaner and free of burrs compared to group “ 1 ”, where uniform slots were also obtained, but without the formation of a skirt. As a consequence, the group of results “ 5 ” is assigned to the area “ C ” on the diagram (Fig. 9), which can be characterized as the area of potentially suitable structures for fi ltering tasks along with the area “ A ”. Fig. 13. Non-regular stripping of slot walls (outer side) Fig. 14. Uniform slots with a continuous burr (“skirt”) formed: а – view on the skirt after cutting through slits, b – the skirt is bent aside а b Group “6” – Slots with a skirt opened incompletely (Fig. 15). At the smallest of the considered feed rates – 0.05 mm/rev – the formation of a “skirt” was noted immediately upon reaching the minimum cut- ting depth suf fi cient for cutting the corrugation. At such shallow cutting depths, the “skirt” partially retains its connection with the material on both sides of the corrugation, which makes it dif fi cult to remove it and for the the fi ltered medium to pass through the slots. However, since the structure of the slots is uniform and the theoretical possibility of removing the skirt is retained, this group is also assigned to area “ C ” in the diagram.