Patent GB-580542-A (GB)
Title: Improvements in or relating to molding presses
IPC: B29C43/00
Filed: 1943-12-13
Abstract: 580,542. Moulding screw caps &c. from thermosetting material in hydraulically-operated moulding presses. NEWTON, E. P. (Stokes Machine Co., F. J.). Dec. 13, 1943, No. 20868. [Class 87 (ii)] [Also in Group XXIX] A power-operated loading carriage is reciprocable between the press and a loading device and carries a feeler element which, on contact with a moulded article which has stuck to a mould part, stops the operation of the carriage (and, in the example described, stops the other parts of the press). The invention is described in connection with a press for making screw caps, comprising a stationary upper heated platen 4 and a vertically-reciprocable lower heated platen 9. The platen 4 carries a die-plate 5 having rotatably mounted therein rows of screw-threaded patrices 6 which co-operate with rows of matrices 9c in a die-plate 9b which rests slidably on the platen 9. Each patrix has a pinion 6b and each row of patrices is engaged by a rack 7, the racks being carried by a cross-head 7a, which is reciprocated by a hydraulic piston 8. The platen 9 is carried by a table 10 which is raised and lowered by a hydraulic cylinder 12 through the intermediary of toggle links 10a. The die-plate 9b slides into and out of the press on a frame which is secured to the table 10 and carries a hopper 14a which feeds powder or preforms to the matrices 9c. The die-plate 9b is moved by a hydraulic piston 13 (which is mounted on the table 10) through the intermediary of geared racks 12a, 12g, and carries to the right of the matrices a series of rubbercovered friction bars 16f, and a feeler bar 18. The hydraulic pistons 8, 12, 13 are operated by pumps 21, 22 driven by an electric motor 20. Sequence of ' operations:-(1) With the press closed (the die-plates being together and the racks 7 to the left, i.e., in the press) the racks move to the right, partly unscrewing the patrices from the moulded screw caps, which are held against rotation by grooves in the walls of the matrices; simultaneously the die-plate 9b descends, the screw caps being pulled out of the matrices and left hanging on the patrices. (2) The die-plate 9b then moves to the left, and the friction bars 16f secured thereto engage the caps and complete the unscrewing operation, at the same time breaking off any flash on the caps. The caps fall into a tray 17 which tilts and empties the caps into a shoot 18<1>. As the die-plate 9b continues its leftward movement, the feeler bar 18 passes just below the patrices 6. If a cap sticks tightly to a patrix the bar 18, making contact with the cap, pivots on an axle and opens an electric switch 19 which breaks the circuit to the electric motor 20, which stops, thereby stopping the press. If a cap adheres weakly to a patrix, the bar 18 strips it off. As the die-plate moves to the left, a jet of air from pipe 15 cleans the matrices. (3) The racks 7 move back into the press. (4) The die-plate 9b with its matrices filled moves back into the press. (5) The die-plate rises and the press remains closed until. the curing is completed. The operation may be automatic, or the various operations may be controlled individually by push-buttons. In a modification, the lower platen remains in the press, and is loaded by a reciprocating loading board which is mounted on a carriage carrying the feeler bar.