GB1293939A - Continuous vacuum casting of metals and metal alloys - Google Patents

Abstract

1293939 Continuous casting SOC INDUSTRIELLE DE COMBUSTIBLE NUCLEAIRE 16 Oct 1969 [18 Oct 1968 15 Sept 1969] 50978/69 Heading B3F [Also in Division C7] In order that continuous casting of metals, such as uranium or steels, may be performed under vacuum (for degassing or protection), the metal flows from a ladle 2, kept at constant temperature by an induction coil 3, through a nozzle 8 into a cooled mould 9 in a vacuum chamber 1 at a rate controlled by a level detector 11, 12 and servo-mechanism 5, 6; from the mould 9 (which may have a 1-2 degree taper), the cast strand passes through a cooling jacket 14 and out of the chamber 1 through a gas seal 15 comprising a series of chambers 27-31, Fig. 2, formed between seals 33-37 and a neutral-gas seal 32 and exhausted by pumps (to successively decreasing pressures). Nitrogen supplied to the seal 32 cools the strand as well as excluding air and the supply, from a source 16, is controlled by a temperature-responsive element 18, Fig. 1, in the seal 32 (with which is associated a cooling- water spray 19). Another temperature-responsive element 23, at the exit of the cooling jacket 14, controls, by way of a servo-mechanism 22, a motor 21 which drives withdrawal rolls 20, 21<SP>1</SP>. The strand is cut into lengths by a travelling cutter 24. A starter bar 25 has a dovetail lug 26 at its end. The flow from the ladle 2 is determined by an electromagnetic pump or, as shown, a plunger 4 and the metal in the ladle may be made-up by a ladle (70, Fig. 6, not shown) set on top of the vacuum chamber 1. The level in the mould 9, observable through a tube 13 may be kept between two sensors 11, 12. The mould may be a Cu tube (110) in a steel cylinder (111, Fig. 7, not shown), through which cooling water flows, and connected between circular plates (108, 109) secured to parallel posts (105, 106) slidable in brackets (102, 103) to allow reciprocation of the arrangement (with faster upward movement) by a cam-operated shaft (124) linked to the lower circular plate (108). The level of the metal surface in the mould in this case is detected by a radio-active radiation source and the probe (125) of a Geiger counter outside the mould. A graphite-cored uranium bar is cast by passing a graphite rod insert (62, Fig. 5, not shown), continuously down into the mould (fed with molten uranium) through a gas seal (64) into the vacuum chamber 1 wherein it is guided by rollers (68) or friction pads and heated by induction unless it is heated before entering the chamber 1.