GB666621A - Improvements in or relating to cutting and abrading tools - Google Patents

Abstract

666,621. Making cutting and abrading tools, gratings, &c. BOOTH, C. H., and HARDWICK, H. B. Nov. 3, 1949 [Nov. 8, 1948], No. 28153/49. [Divided out of 666,573.] Class 83 (ii). [Also in Group XXIII] A method of producing hardened cutting edges on the surface of a strip of thin flexible steel to be used in or as a file, rasp or cutting or abrading band or disc, in the manner described in Specifications 666,673 and 666,622 comprises upsetting several portions of the strip to an extent equal to the thickness of the material and to make an acute angle with the surface, removing wholly or partly the upset portions to produce a sharp edge, upsetting the sharp edge and differentially hardening the edges with respect to the body of the strip. Tongues 10 having semi-circular ends are first upset from the strip by means of punches and dies so that the whole and preferably only the whole of the semi-circular end is below the surface of the strip, Fig. 7. The portion of the tongue below the strip is then ground off and the edge 12, Fig. 9, is upset and, if necessary, sharpened by sand-blasting or other means. Cutting-edges may be produced on both sides of the strip, as shown in Fig. 6, the tongues being then pressed up in opposite directions from a straight dividing line. The rate of grinding may be so determined that the heat developed is sufficient to harden the edge 12 without substantially affecting the body of the strip, or the strip may be placed in a furnace for a time sufficient to heat only the sharpened edges to hardening temperature.