Patent GB-543605-A (GB)
Title: Apparatus for molding plastic materials
IPC: B30B15/30
Filed: 1940-05-06
Abstract: 543,605. Moulding ; control of two motors; delivering measured quantities of granular material. HARTFORD-EMPIRE CO. May 6, 1940, No. 8130. Convention date, May 10, 1939. [Class 87 (ii)] [Also in Groups XVIII and XXXVII] Powder is fed from a powder measuring device A into measuring cups 18, thence into pockets 26 of a powder carrier 28, and the powder carrier moves into a pill press B where the powder is discharged from the pockets 26 into mould cavities 176. The press B is a preforming press, whence preforms are delivered by a pill board E to a moulding press C, and may be omitted, powder being then transferred direct from the measurer A to the press C. The presses may be heated. The pill board E may have an extension F, for receiving and discharging moulded pieces from the press C. Powder fed into a hopper 12 supported by springs 56 from a frame 48 falls through tubes 14 into a powder box 16 and thence into the measuring cups 18 having discharge valves 22 and cut-off plates 20 spaced from the base of the box 16 by pins 86. The powder box 16 may be raised by means of a handle 32 and links 58, 60, the box sliding on columns 52 and screws 30 being raised out of funnels 24 so that the capacity of the cups may be adjusted ; the capacity of the cups may be reduced by inserting sleeves therein. From the cups the powder falls through funnels 24, which may be joined at their rims, into the pockets 26. The cups may be vibrated, as by small vibrators of the type used in electric shavers. Operation (1).-With the cavities 176 filled with powder, the powder carrier under the powder box 16, the valves 22 closed, the cut-off plates 20 open and the pill board in the press B, the press B is closed by descent of platen 496. This descent closes a switch 346 which energizes a solenoid 306 via segment 1, arm 276 and slip ring 278 of a sequence relay. Energization of the solenoid (a) makes a contact 308 to start the sequence-relay-operating motor 284 and (b) moves a dog 296 out of a notch in a driving disc 294 allowing the motor 284 to drive the disc through one complete revolution and move the arm 276 to segment 2. The solenoid is thus de-energized, the contact 308 is opened, and the dog drops back into the notch. As the platen 496 descends, plungers 512 thereon, passing through apertures E<SP>1</SP> in the pill board E, compress the powder into preforms. (2) The platen 496 ascends, and ejector plugs 178, raised by a plate 520, push the preforms into the apertures E<SP>1</SP>, where they are held by springs 492. Ascent of platen 496 closes a switch 348, energizing the solenoid 306 and stepping the arm 276 to segment 3 ; during this step, powder carrier switch 320 is closed by cam 316. (3) The pill board is moved manually out of the press B, a wheel 354, on which the board runs, moving from under a spring-pressed arm 356 and allowing a contact 352 to be made. (4) A switch 350 is manually closed (but in a modification the contact 352 and switch 350 are replaced by a switch 472 operated by a pin 484 on the pill board on movement of the latter). With switch 350 and contact 352 closed, the contacts of a relay.R-11 are reversed from the position shown, thereby via arm 244 and switch 320 making the circuits of a powder carrier motor 188, which thereupon, via gears and toothed racks moves the powder carrier, with its load of powder, into the press B. As the carrier completes its entering movement bars 174 thereon abut against a stop in the press and open vanes 166 which normally close the pockets 26. The powder falls into the cavities 176. As the motor 188 turns it moves cams which move motor-controlling arms 244 and 246 anti-clockwise and clockwise respectively. When arm 244 reaches contact 420 a resistance 342 is inserted in the circuit of the field coil 408, so that the speed of the motor 188 decreases, and when it reaches contact 422 the field coil circuit is broken ; conversely, arm 246 moves from dead through slow to (potentially) live. With arm 244 on contact 422, solenoid 306 is energized and the arm 276 is stepped to segment 4. (5) Switch 350 is manually opened (or switch 472 is operated by movement of pill board E towards press B). This de-energizes relay R-11, reverses the contacts to the position shown, energizes the motor 188 through arm 246 (the field coil current being reversed), and the motor withdraws the powder carrier from the press. During the withdrawing movement springs 170 close the vanes 166 ; closure is ensured by a stop on the powder measurer, against which the bars 174 abut. When the arm 246 reaches the contact 442 the solenoid 306 is energized and the arm 276 is stepped to segment 5. As the arm 276 moves from segment 4 to segment 5 cam 316 opens switch 320 and cam 318 closes powder measurer switch 322. Closing of switch 322 energizes relay R-12, making the contact 458-462 and, via D2-F2 of contact drum 142, energizing a motor 36 which turns a cam shaft 34 half a revolution. This cam shaft moves the cut-off plates 20 to the closed position, and depresses a plate 94 to open valves 22 against springs 96 and 98. The pockets 26 in the carrier are thus filled. The control drum 142 is fixed on the cam shaft 34, and at the end of the half revolution a momentary contact D4-F4 is made which steps the arm 276 from segment 5 to segment 1, thus opening the powder measuring switch 322, making contact 458-470, and, via D3-F3, turning cam shaft 34 half a revolution, thus opening the cut-off plates 20 and closing the valves 22. Specifications 534,753 and 536,437 are referred to. The Specification as open' to inspection under Sect. 91 states that the presses may be controlled by interconnected manually operated valves or by valves operated automatically by motor-driven timing mechanism. This subjectmatter does not appear in the Specification as accepted.