GB525095A - Improvements in or relating to abrading tools - Google Patents

Abstract

525,095. Grinding-tools. TENNANT, W. J. (American Optical Co.). Feb. 16, 1939, No. 5033. [Class 60] [Also in Groups II, IV and V] An abrading tool comprises an abrading layer 2 formed of a mixture of abrasive particles, for example, carborundum or diamond, and metal particles, the mixture being pressed in a mould and heated to sintering temperature, the operation being so conducted as to render the body porous, and a second layer 1 composed only of the bonding material integrally joined to and constituting a permanent support for the layer 2, and a third layer composed of a solid metallic material having one surface shaped to engage and be detachably secured to the second layer and the other face shaped for mounting on a spindle during abrading action. The abrading face 2 is subsequently, or during formation, hardened and may be ground or treated with acid to expose the abrasive particles. The body 1 may have a central aperture registering as shown in Fig. 2, with a spigot on a support 6, to which the body is secured, for example, by screws 7. In a modification, Fig. 5, the body 13 has therein grooves 12 in which are moulded or secured by solder, abrasive portions 10 formed as described above, and in a further modification the abrasive members are in the form of plugs secured in holes in the body. The body may have in its surface spiral or other grooves running in a generally radial direction to receive and eject abraded material. The portion 2 may be thin and may be soldered to the body 1. The metal bonding material may be particles of alloy comprising 80 per cent. copper, 5 per cent. tin, and 15 per cent. nickel. 25 carats of diamonds may be incorporated in each cubic inch of the abrading layer. Beryllium or other bronze, copper, iron and iron alloys, especially nitralloy may be employed: The particles may be pressed cold in a metal mould or hot in a graphite or ceramic mould. When the copper-tin-nickel alloy is used the pressure applied is from 5 to 10 thousand pounds per square inch and the mixture is heated whilst held under pressure to between 1,500‹F. and 1,700‹F. The material sold under the Registered Trade Mark " Bakelite " or rubber compositions or a synthetic resin such as methyl-methacrylate may be employed as a bond. Soluble particles are mixed with the resin prior to polymerization when a porous bonding is required.