GB536508A - Abrasive wheel - Google Patents

Abstract

536,508. Abrasive wheels. NORTON GRINDING WHEEL CO., Ltd. March 29, 1940, No. 5725. Convention date, March 29, 1939. [Class 60] [Also in Group V] An abrasive wheel for grinding cemented carbide cutting tools &c. comprises a cured organic backing 30, Fig. 5, interlocked at 22 with a backing 20, consisting of at least 95 per cent. metal, and an abrasive portion 21, integral with the backing and consisting of abrasive grains bonded with metal which comprises 50 per cent. by volume of the portion 21. The part 30 may consist of natural or artificial resin or hard rubber, the part 20 of copper with another metal or element which will make it brittle as described in Specification 479,790, [Group V], and the part 21 of material similar to that used for the part 20 with the addition of 25 per cent. by volume of diamonds, fused alumina, emery, corundum, silicon carbide, boron carbide, or the last two materials fused together. Powder for making the part 20 is placed in a mould comprising parts 10, 11, 13, 14, Fig. 3, in such quantity that, when pressed by a ring 12 in a press, a pressure of about 12,500 pounds to the square inch is produced. After pressure has been applied, the ring 12 is removed and material for the part 21 introduced in such quantity that when again pressed a pressure of about 50,000 pounds is produced. The pressed compound ring 20, 21 is removed and heated to about 500‹ C. for five hours in a reducing or inert atmosphere. Recesses, such as turned under-cut grooves 23, Fig. 5, are then formed in the exposed face of the part 20 and the compound ring is placed, with the recessed face upwards, in the mould, inverted as shown in Fig. 5. Powdered resin or the like 30 is then introduced and pressed by a ring 29. In the case of phenol formaldehyde moulding-powder a pressure of about 6,000 pounds per square inch and temperature of 160‹ C. for half an hour may be used.