GB666573A - Improvements in or relating to cutting and abrading tools - Google Patents

Abstract

666,573. Making cutting and abrading tools, gratings, &c. BOOTH, C. H., and HARDWICK, H. B. Nov. 3, 1949 [Nov. 8, 1948], No. 28991/48. Class 83 (ii). [Also in Groups I, VI and XXIII] A cutting element for use as a file, rasp or cutting band or disc comprises a thin flexible strip of hardenable steel having holes 1 with cutting edges 2 formed by upset portions of the edges of the holes, each edge having a cutting clearance angle A relative to the surface of the strip and being differentially hardened relative to the remainder of the strip, which thus retains its flexibility. The cutting edges may be formed and hardened as described in Specification 666,621. The strip has a thickness of between 0.003 and <SP>1</SP>/ 32 inch and the holes 2 are arranged in V-shaped rows, the holes in one row being staggered in relation to those in adjacent rows. The holes may be either circular and countersunk, Fig. 8, with rather less than the rear half of the circumference upset to form the cutting edge, or D-shaped, with the cutting edge formed by the straight part of the hole. The amount by which the cutting edge projects from the strip is from 3 to 15 thousandths of an inch and varies from a maximum at the centre of the edge to nil at the ends. For use on soft materials such as wood or leather, the clearance angle A would be about 10-50 degrees and the rake angle B about 45 degrees, decreasing in both cases until, for moderately hard metals, they would be about 7 degrees and 10-15 degrees respectively. The shear angle provided by the V-shaped arrangement of the rows may be varied as required and may differ in amount or direction for different cutting edges. Cutting edges may be provided on both faces of the strip. The strips may be bent into a tube to form a round file or rasp or a rotatable drum having cutting edges inside or outside or both. Alternatively, two or more strips may be joined by welding, brazing or mechanical joints to form tools as exemplified in Figs. 12 and 13 and may have supporting strips 24a or 31; the cutting- edges are omitted over a portion of the tool to form a handle 33. The strips may also be used with backing members to form tools as described in Specification 666,622. The tools are stated to be applicable to making wood wool, to stripping motor tyres for retreading and to peeling vegetables, in addition to the normal operations in which files, rasps or abrasive sheets, bands and dies are normally used.