Improvements in or relating to the manufacture of hard metal carbide articles, and more particularly to hard metal carbide articles of substantial size, such as rolling mill rolls

摘要

506,728. Alloys; electric furnaces; rolling. METAL CARBIDES CORPORATION. Nov. 1, 1937, No. 29829. Convention date, Sept. 9. [Class 82 (i)] [Also in Groups XI and XXII] Articles such as rolling - mill rolls are formed from powdered material containing metal carbides and a metallic binder by compressing the material in a mould and locally and progressively heating the material in a zone moving in the direction in which pressure is exerted. The heating may progress from one end to the other or from the centre outwards to the ends of the mould. The articles formed may be solid or tubular. The carbides may be tungsten, molybdenum, vanadium, chromium, tantalum, or titanium, and the metal may be iron, cobalt, or nickel. The material is placed in a carbon or graphite mould 52 surrounded by carbon packing 54, an insulating sheath 51 and electric heating coils 60. The mould may be of refractory material such as magnesia, zirconia, and chromite. Compression is effected by a plunger or forging hammer 70 operated hydraulically. In one form, small slugs 101 of the powder are successively formed in the mould under heat and pressure and progressively welded together. Thus, powder 100a for the second slug is placed on the preformed slug 101. Smaller intermediate portions of the powder may be compressed between each slug to assist in welding. The slugs may be formed outside the mould under pressure, with or without heating, then superposed in the mould and welded together by progressive heating under pressure. Rings or tubes may be formed similarly in a mould 51, Fig. 20, by means of a spindle 57 and an annular piston 71. The material may be compressed by opposed pistons. When the mould is made of refractory material such as magnesia, the heating is effected by inductiom The heating coils 60 may be individually controlled so that the heating zone can be progressively moved or the heating coils may themselves be moved along the mould. The hollow cylinders may be used as working surfaces for rolls and may be provided with central shafts of steel or other metal which may be cast therein or secured thereto. The rolls may be mounted in a four-high mill.