Patent GB-794037-A (GB)
Title: Improvements in or relating to die-casting and injection-moulding machines
Inventor: KELLETT ERIC
IPC: B22D17/32
Filed: 1955-02-25
Abstract: 794,037. Injection-moulding machines. BIRMINGHAM SMALL ARMS CO., Ltd. Feb. 21, 1956 [Feb. 25, 1955], No. 5632/55. Class 87(2). [Also in Group XXII] A die-casting or injection moulding machine comprises jacks operable by oil under pressure and in operative connection with an injector, an ejector, at least one movable part carrying a die part and at least one other part capable of movement, including a screwing movement, that is other than coaxial relative to the movement of that die part, switches for electrically-operated valves to control the supply of oil to the jacks, at least one of the switches being adjustably disposed for operation by movement of one of the two parts that have relative non-co-axial movements to put the other of the parts into simultaneous movement at any desired time in the movement of the first, and control means to initiate movement of the said first of these two parts after solidification of the moulding material in the die. Oil is drawn from a tank 1 by a low pressure variable speed pump 3 and a high pressure pump 4 delivering to a main line 9 connected with an accumulator 14. A pressure switch 16 controls a valve 13 to prevent flow from the accumulator below a pressure of, e.g. 1600 lbs./in<SP>2</SP>. Oil flows from the line 9 through restrictor valve 19 and check valve 20 to a solenoid actuated valve A<SP>11</SP>, from whence it flows to a solenoid actuated valve A<SP>1</SP> and to an inner cylinder 22 of the die jack.A. From the valve A<SP>1</SP> oil passes via line 24 to a valve 25 to open a pre-filler tank 26 to the rear cylinder 27 of the jack A so that oil is sucked into 27 as the jack closes the die. A trip actuated by the die movement reverses valve A<SP>1</SP> to close valve 25 so that oil is directed to the cylinder 22 at a slower speed to cushion the closing of the jack A. To open the die valve All is reversed and oil flows to valve A<SP>1</SP> which is simultaneously operated to re-open valve 25. Oil also flows through line 31 to the forward cylinder 32 of the jack A and oil is pushed from the rear cylinder 27 to the tank 26-and from cylinder 22 to the tank 1. For injection oil flow to the injector jack B is controlled by a solenoid actuated valve Bi controlling a valve E. The ejection jack C is supplied with oil from the main line 9 through a solenoid actuated valve C<SP>1</SP> and retraction of the core is effected by oil supplied to the core jack D from the line 9 through a solenoid actuated valve D<SP>1</SP>. The sequence of operations is shown in timing diagram, Fig. 7. Molten metal is ladled in up to point I, when start button a, Fig. 6, is pressed which energizes valve B<SP>1</SP> to effect injection up to point II and simultaneously energizes a process timer g which controls the freezing period. At point III, the end of freezing, the timer actuates a switch h to energize valve D<SP>1</SP> to start core withdrawal, which continues to point IV when a microswitch on the core mechanism energizes valves A<SP>1</SP>, A<SP>11</SP>, which start die opening at point IV. A switch l on the die mechanism is opened to halt die opening from points V-VI, when a switch m causes die opening to continue. Core withdrawal continues to VII, when a switch n energizes valve C<SP>1</SP>, thus causing ejection of the casting. The operator now presses button b to energize valves D<SP>1</SP> and A<SP>1</SP> to commence die closing and core insertion. At point VIII when die is fully open a switch s energizes the valve B<SP>1</SP> to return the injector and to cut out the timer g. At point IX a switch u on the die motion energizes the valve C<SP>1</SP> to return the ejector to point X. The die closing meanwhile continues to point XI, when a switch x halts the die. The core is still returning and at point XII a switch w re-starts die closing. Fig. 9 shows diagrammatically the use of two pumps with the accumulator available to supply oil to the die and injection jacks A, B, and Fig. 10, the use of two pumps with the accumulator supplied by one pump only to operate the injection jack B.