| 摘要 |
1463137 Rock drill bits COAL INDUSTRY (PATENTS) Ltd 10 April 1975 [24 April 1974 31 May 1974] 17909/74 and 24284/74 Heading B3C [Also in Division E1] A rock cutting tip insert comprises a cutting margin 5 of one hardness level and a backing portion 6 of a second hardness level, the first hardness level being at least 100, preferably at least 400, units on the Vickers Hardness scale greater than the second hardness level. The cutting margin may be formed of the same material, e.g. cemented carbide, as the backing portion, but subjected to a hardening process. The cutting margin and/or the backing portion may be formed of a hard mineral or ceramic, or of a composite material in which hard mineral or ceramic particles are embedded in a softer matrix. |
