Improvements in or relating to injection-moulding and compression-moulding presses for moulding thermo-setting resins

摘要

580,331. Injection-moulding and compressionmoulding of thermosetting resins. DANIELS, Ltd., T. H. & J., and FREUND, M. June 30, 1944, No. 12512. [Class 87 (ii)] An injection moulding or com pression - mould ing press fo thermosetting resins include five crossheads the central on and the out side ones being fixed and th intermediate one adapted to be moved toward the central one by means o hydraulic ram associated with the outside cross heads. Fig. shows an in jection - moulding machine compris ing five crossheads mounted on four slide-bars 16, 17 The central cross head carries the upper half 22 of a mould and ar injection sleeve 23 whilst the lower half of the mould is carrie( by the crosshead 14. An injection plunger 21 i fixed to the cross head 12. Hydraulic rams associated with the outermost members 11, 15 press the intermediate crossheads towards the central crosshead so that the mould is closed and plastic material injected from the sleeve when the plunger descends. Means for heating the sleeve and the mould are provided. When the ring-shaped moulding 25, Fig. 3 has set, the plunger may be further depressed to eject the moulding and the central slug 31 remaining in the sleeve. Alternatively, the lower orifice of the sleeve may be contracted to form a nozzle and the plunger provided with a "corkscrew" end so that after setting, when the plunger is withdrawn, the slug breaks at its narrowest point and is afterwards removed with the moulded article. In modifications (not shown) (1) The press is inverted so that the injection plunger moves upwardly and the top half of the. mould downwardly; (2) the press is adapted to serve as a standard compression-moulding machine. In this case the central crosshead carries two halfmoulds, one directed upwardly and the other downwardly, whilst the intermediate crossheads carry the other halves.