| 摘要 |
1453806 Abrasive tools; brazing G H HALL 15 July 1974 [19 July 1973] 31251/74 Headings B3D and B3R A method of forming a cutting tool having a plurality of blocks 24 of composite comminuted abrasive in a bonding matrix affixed to a substrate 22 comprises connecting the blocks to the substrate by a braze comprising a layer 36 of an elastically pliant material having high thermal conductivity bonded to both the substrate and blocks by a metallic material 34, 38 which has a melting point below the melting point of both the matrix and substrate. The cutting tool is in the form of an endless wire 20 having helical grooves 26 formed in its surface and in which the abrasive blocks 24 are brazed. The wire is of cold worked and maraged steel of circular, elliptical, triangular or square cross-section and the grooves 26 are cold rolled into the wire. The brazing strip 32 is placed in the grooves and consists of the elastically pliant layer 36 of pure copper between two layers 34, 38 comprising, by weight, 50% silver, 16% cadmium, 15À5% of each of copper and zinc, and 3% nickel. The blocks 24 consist of diamond particles of different sizes, such as, by volume, 40% of 40-50 mesh, 40% of 50-60 mesh, and 20% of 60-30 mesh, although the particles may vary from 1 to 1200 microns in size. The matrix comprises principally copper or other malleable metal, whereby flexing of the wire does not cause cracking of the matrix, zinc, iron, tin, titanium, chromium, zirconium and brazing powder. The mixture of particles and matrix are shaped into the blocks and cured at 1000‹ C. for 1 minute. The cured blocks, which may be ¢ inch long, are clamped with a pressure of 100 psi in the slots and the wire induction heated to effect brazing by bonding of the metallic layers 34, 38 to the elastic layer 36 and the blocks and wire. The wire 20 is formed as a continuous loop 40 guided over sheaves 42, 44 driven by a motor and pulley arrangement 50, the layer 36 of the braze 32 being pliant to accommodate bending of the wire as it runs over the sheaves. The sheave 42, and preferably also sheave 40, have surfaces (56, Fig. 4, not shown) of elastically pliant material which causes the wire to rotate above its axis. The wire cutting tool may be used to cut a workpiece 32, such as granite, raised by an elevator with engagement with the tool. |
