Patent GB-574487-A (GB)
Title: Method of moulding articles from metal or other material
IPC: B22D17/00
Filed: 1943-07-01
Abstract: 574,487. Injection-moulding machines. MISFELDT, C. C. July 1, 1943, No. 10696. [Class 87 (ii)] [Also in Group XXII] The material, heated to a point just below.the plastic state, is forced through a constricted orifice 80, Fig. 2, into the die 25 thereby raising the temperature and making it plastic. When the die is full, a higher pressure is applied until the casting sets. The material may be supplied to the machine in the form of slugs which are loaded into electrically heated recesses 21 in a rotary drum 20. The heating may be done in three stages by automatically connecting each heater coil, by means of brushes 63, Fig. 5, to contact strips 66, 67, 68, in succession as the drum 20 is rotated, electric current being fed through resistances 70. When a heated slug reaches the position 168 it is in line with a plunger 76, Fig. 2, and forcing chamber 73, also electrically heated. A valve 110 is then operated to force the slug, by means of highpressure fluid and a piston 11 which carries the plunger 76 into the chamber 73 and then through a nozzle 80 into the two-part die 25. This is clamped against the block 6 by a head 15 which is operated by a piston 11<1> and valve 108 which admits low-pressure fluid. The die 25 and its clamps are electrically heated, preferably to such a temperature that the high pressure, produced in the die when this is full, occurs just before the material solidifies. As the plunger 76 reaches the final position, an inner plunger 52, operated by a piston 46, Fig. 4, in a cylinder within the piston 11, and a valve 118, is allowed to withdraw slightly so that material flows into the threaded bore 51, Fig. 8. The cut-off plate .85 is then moved ,down by a piston 86 until its bore is opposite a knock-out 87 operated ,by ,a piston 88. The piston 11 is then withdrawn by low-pressure fluid by opening a valve 113, valve 110 being turned to exhaust, thus withdrawing the residue 201, Fig. 8, into the open where it is unscrewed from the plunger 76. In some cases one slug will produce a number of castings and with some materials the residue need not be removed, but will fuse with the fresh slug. If a hollow article is required, a hollow core 42<1>, Fig. 12, may be advanced through the die 25, by means of a piston 46<1> movable in a cylinder within the piston 11<1>, and .into engagement with an enlarged tip 2,10 o,n the hollow plunger 42 which has ,been advanced through a hollow slug. After the material has been forced by the plunger 76 over the tip 210 and into the die, the tip is moved to the right to sever the material and then to the left to withdraw the residue 201, the cut-off plate 85 being omitted. In another modification, a tubular core is introduced into the die through the hollow plunger 42 and allowed to remain in the cast article, the cut-off plate severing the core tube which, after the article and residue have been removed, is advanced for another operation. The machine may also be modified so as to use material in powder form or cast, forged, or cut pieces. The machine may be operated by hand or be made semi- or fully automatic.