GB722188A - Improvements in or relating to method of machining ferrous metals - Google Patents

Abstract

722,188. Milling-cutters. LA SALLE STEEL CO. Dec. 11, 1951, No. 28976/51. Class 83 (3). Special processes.-A method of machining ferrous metal consists in moving a continuous series of cutting teeth having a spacing uf ¢ inch or less successively into engagement with a workpiece at a tooth travel-rate in excess of 1,000 ft./min., maintaining at least two teeth in engagement with the work at all times, and moving the work and teeth at a relative speed in excess of 90 ins./min. In milling work 16, Fig. 2, two cutters are rotated about their axes at 1,500 r.p.m. and are also rotated about the work which is fed at 50 ft./min. Each cutter has teeth pitched at “ inch and ground from a carbide body, the diameter being 4 inches. The depth of cut is <SP>1</SP>/ 32 inch. The work may be rotated and the cutters rotated about their axes only. A second form of cutter has a body 20, Figs. 5, 6, formed with slots 21, 22 into which are placed blade elements 24 having- a helix angle of, preferably, 18 degrees, and a pitch of approximately “ inch for a 12 inch diameter body. The blades are secured by a non-resilient organic plastic or metal alloy which is forced around the blades and into recesses 25, 26, the plastic or alloy being subsequently partly removed to provide chip clearance-spaces and the blades ground to the required profile. The cutter is rotated at 500 r.p.m. with a chip size of 0.005 inch and a feed rate of 375 ins./min. In a machine for using the cutter, the feed-screw was rotated at 1200 r.p.m. to give a feed of 600 ins./min., the spindle speed being increased to 1,462 r.p.m. Other performance figures for current practice and for the present method are quoted.