Patent GB-807868-A (GB)
Title: Improvements in and relating to casting processes and apparatus
Inventor: STIVIN JIRI
IPC: B22D13/00
Filed: 1956-12-11
Abstract: 807,868. Casting-machines; rolling. VYZKUMNY USTAV OBRABECICH STROJU A OBRABENI PRAHA. Dec. 11, 1956, No. 37844/56. Classes 83 (1) and 83 (4). [Also in Group XXIII] A casting-process comprises moving one or more bodies along a closed-path during casting, in such manner that the inner or outer envelope of the individual positions of the body or bodies constitutes a limiting-face of the casting-mould, and passing said body or bodies over individual portions of the surface of the casting in such sequence and at such intervals that outward movement of the cast material between the passage of the body or bodies is limited to an amount which can be pushed back by the following body. An ingot-casting-mould comprises a stationary frame 1-4, in which is rotatably-supported a disc 12 which may be driven through a circumferential gear 13. Rotatably supported on the disc 12 on pivots 16 are rollers 19 comprising gears 22 which engage a central stationary-gear 23. When the disc 12 is rotated the rollers 19 rotate with it at a speed such that when molten metal is poured through the tube 6 it is unable to escape between the rollers 19. At the same time the rollers are rotated about their axes by engagement of the gears 22, 23, at a speed such that they roll on the surface of the casting without slipping. In a modification, the stationary inner-gear 23 may be replaced by an external ring-gear driven at double the angular speed of the individual rollers. The rollers should not be wetted by the metal cast, or this will be thrown out, and may be of a material of a melting-point lower than that of the metal cast, since the cooling of the rollers is intense due to the greater part of their travel being at high-speed in air. The cooling may be supplemented by a coolant fed radially between the rollers, or through hollow components of the machine. Alternatively the rollers may be wetted by impurities such as slag so that these adhere to the rollers and are then thrown off by centrifugal force. In a further modification the rollers are of the same material as that being cast, e.g. glass. Since each following-roller pushes back the melt which is projected radially-outward to some extent, the metal is set in a swinging motion which facilitates the escape of gas therefrom, mixes the melt and favours crystallization. A centrifugal action may also be imposed on the melt by rotating the whole apparatus about its axis or by choosing the diameters of the gears 22-23 so that the surface of each roller 19 moves relatively to the surface of the casting, thus exerting a frictional force on the cast material and imparting rotation thereto. The apparatus may be enclosed in a neutral or other gaseous, or reduced-pressure, atmosphere. The invention may be applied to sections other than circular, e.g. L-shaped, Fig. 2. Hollow castings may be cast in a permanent outer mould, the inner surface being produced by a rotating roller, or both inner and outer surfaces may be shaped by rotating rollers. In a further modification, Fig. 4, for lining bearing-bushes 41 with babbitt-metal, the inner wall being shaped by rollers 44, which are rotated on their axes by frictional engagement with the mould closing plate 1. In a further modification the rollers, in the course of their circling movement, may move towards the axis of the casting to vary the diameter of the mould and prevent the occurrence of shrinkage cavities. Multi-layer castings may be made by first casting a core, then moving the rollers apart so as to leave an annular gap between the core and the inner envelope of the rollers, into which more metal is poured. Multi-layer hollow castings may be produced, e.g. by first casting a bearing bush, then reducing the diameter of rotation of the inner cylinder, and casting-in babbitt metal. In a further modification, Fig. 9, castings having portions of difierent diameters may be cast by the use of several rollers 93, 102. Some eccentricity of one or more portions may be imparted if desired. Continuous casting; rolling.-In a continuouscasting machine, Fig. 10, rotary rollers 129 are helically grooved to feed down the casting, the depth of the grooves diminishing towards the exit end of the mould so that a smooth casting emerges. Fluted, ribbed or other sectioned bars may be cast by providing the rollers with corresponding ribs &c. Alternatively, the bottom ends only of the rollers, where the material cast is already solidified at a forging temperature, may include such shaping-elements. The continuous-casting may be divided by feeding, at intervals, material which will not unite with the cast material. Heating by electricity.-The metal in the mould may be heated, using the rollers as electrodes,'or by high-frequency conductors placed between the rotary bodies.