GB605261A - Improvements in the manufacture of powder metal compacts and diamond tools - Google Patents

Abstract

605,261. Making diamond tools; powder metallurgy. BOART PRODUCTS, SOUTH AFRICA (PROPRIETARY), Ltd. March 5, 1945, No. 5496. Convention date, April 6, 1944. [Classes 83 (ii) and 83 (iv)] [Also in Groups V and XXIII] A process of manufacturing a coherent body of metal powder comprises heating a moulded mass of the powder to sintering temperature, enclosing the hot body in a mould and compressing it while at sintering temperature. As applied to the manufacture of a diamondboring tool, diamonds 5, 6 are arranged in recesses formed in the upper surface of a plug 8 which closes the lower end of a light metal cylinder 7. The required amount of metal powder 14 is put into the cylinder which is then closed by a plunger 11 so shaped at its lower end as to facilitate its becoming firmly attached to the powder mass during sintering, to form the shank of the finished tool. This assembly is placed within a mould comprising a base plate 25 to which is hinged a comparatively heavy outer wall 15 with an internal taper 16 and a split sleeve 17 with a corresponding external taper closely surrounding the casing 7 and preventing distortion of the casing during the compression of the powder. A pressure of the order of twenty tons per square inch is applied to the cold powder by the action of the press ram 27 on the plunger 11. The casing assembly 7, 8 and 11 is then removed to a furnace and heated to sintering temperature, preferably 850‹C. to 950‹ C., after which it is given a further compression in the mould and then allowed to cool. In a modification, a core pin intended to form a part of a finished boring tool is assembled within the centre of the casing 7, the plug 8 and plunger 11 being in this case annular. For forming a diamond dressing tool, metal powder 14a and a diamond 35 are placed in a cylindrical recess formed in a shank 32x and are compressed within a mould by a plunger adapted to enter the end of the recess and then heated and repressed as before. The shank, the sintered metal powder and the diamond are then machined to the form shown in Fig. 9. Specification 614,544 is referred to.