Patent GB-215522-A (GB)
Title: Improvements in and relating to die casting and similar operations
IPC: B22D17/04
Filed: 1923-03-26
Abstract: 215,522. Ellis, G. B., (Murray, T. E.). March 26, 1923. Cased or compound forms; pipes; wheels and pulleys; toothed gearing; electric fittings.-In a method of die-casting, press-forging, and extruding metal parts, the metal to be treated is heated electrically, preferably by a very heavy current of short duration, and then shaped to the desired form. Two or more metals may be heated in the same chamber to form an alloy and examples are given of the making! of pipe fittings, electric terminal sockets, toothed gears and gear blanks. In Figs. 1 and 2 a blank or a lug of metal is located in a heating chamber 2 between electrodes 6, 7 which are pressed together to force the heated metal through openings 3 into the spaces 4 of a split mould 1, the final product consisting of cylindrical portions in the spaces 4 joined to a disc formed between the lines 8 and 9. The blank mav be of such size that the whole of the metal is forced into the chamber 4 a number of which may be arranged round the heating chamber. The current employed may be about 90000 amps per square inch applied for approximately a quarter of a second. In a modification arcs may be formed between the electrodes and the blank to produce the preliminary heating the pressure being subsequently applied. Normally when resistance heating is used the pressure is first applied then the current is. switched on for the required time and the pressure continued to finish the operation, but this method of procedure may be modified. In a modification, Fig. 4, two blanks of different metals may be arranged between pairs of insulated electrodes the current supplied to each pair being regulated according to the melting points of the metals under treatment, and in a further modification the two metals mav be heated separately and forced into a common moulding chamber. The heating of the blanks may in this case be such that the product may either be an alloy of the two metals or may consist of one half of one metal and half of the other. In Fig. 8 a closed tube is made from a blank 5, the mould being provided with a core 27 bolted in position by means of a flange 28. In a modification a tubular tee is made in a similar manner. In a further modification, Fig. 12, two blanks of different metals are employed, the blanks 34 being of hollow cylindrical form and heated by cylindrical electrodes 37. In a further modification. Fig. 14, for making an electric terminal connection air or another oxidizing gas may be admitted through a pipe 54 into the heating chamber so as to force the metal into the mould. Fig. 16 shows the application of the process to the manufacture of a toothed wheel comprising a toothed rim connected by spokes to a hub. The blank 5 is centred by means of recesses 63 in the electrodes. In a further modification, Figs. 20 and 21, a gear blank 63 of aluminium or other soft metal is formed round a reinforcing disc 67 of steel or similar strong metal. The mould 68 is of tubular form and the upper terminal 71 is moved downwards to press the product to the required form. In another modification Fig. 23 the electrode terminals are stationary and the blank 76 is compressed to fill the split mould 75 by means of a plunger 77. In further modifications open moulds may be used which may be arranged to close when the charging of the product is substantially complete. The moulds may be of various materials such as chilled cast steel or of non metallic substances such as paper, plaster, wood, sand. The heating chambers may be made as a unit with the moulding chamber or chambers formed as a unit for attachment to the heating unit.