GB379047A - Improvements relating to built-up metal cutting and other tools or implements and toprocesses and apparatus for their manufacture - Google Patents

Abstract

379,047. Making metal-cutting and like tools. KRUPP AKT.-GES., F., Essen, Germany. July 6, 1931, No. 19416. Convention date, April 18. [Classes 83 (ii) and 83 (iv).] Forging-dies; welding.-Tips for metal-cutting or other tools and implements formed of sintered or fused carbides of metals of melting point over 2000‹ C., such as tungsten carbide, are united to a foundation body of a metal or alloy such as steel by subjecting them simultaneously to pressure and high temperature. The tip may also contain a metal of lower melting point such as cobalt, nickel or iron. The shank B of a turning tool, which has a recess preferably provided with a pin b<1>, is passed along a groove c<2> in a plate C through a slot in a mould E, the hard part G, which may be in powder form, poured thereon and a plunger D engaged by a carbon cap F inserted in the mould. The parts, which are inserted in a press, are connected through C, F to the electric current for heating the powder in about one minute to over 1400-1600‹ C so as to sinter the powder and under the pressure of about 140-280 lbs. per sq. in. to unite it to the shank B. The shank is heated to dull red heat during the process. Tips for turning tools or drill crowns may be united to the end of a shank B, provided with a pin b<2> by securing the shank to a block H serving as a support and inserting it axially into the mould and applying heat and pressure as in the first case. In forming a tip G on the end of a drill shank B, the shank is passed through a hole e<4> in a two-part mould containing an opposite pair of plungers D<1>, D<2>. The parts of the mould have a parting surface which may be radial, stepped or semicircular. The mould may be of wood carbon or graphite, or of wood carbon or ceramic material such as aluminium oxide, surrounded by a graphite sheath. The plungers may be of wood carbon, graphite or ceramic material. The tip, which may be of pure tungsten carbide or tungsten carbide alloy consisting of 90 per cent tungsten, 5 per cent carbon and 5 per cent cobalt, instead of being applied in powder form, may be applied as an unworked thin plate either preliminarily cold-pressed or preliminarily sintered, in which case it is sintered or finally sintered, during uniting, or it may be applied as a finally sintered or cast plate. A leaf or foil of a metal alloy such as 42 per cent nickel steel, having a coefficient of expansion approximately the same as that of the hard metal may be inserted between the foundation body and the tip, to reduce heat strains or cracks.