GB786248A - Improvements in or relating to die casting, injection moulding and other pressure machines - Google Patents

Abstract

786,248. -Casting-machines. BUHLER, GEB. March 2, 1956 [March 3, 1955], No. 6675/56. Class 83 (1). In a die-casting, injection-moulding or like machine having one die mounted on a stationary platen and a second die on a movable platen, the movable platen is formed of a rear part and a front part which are relatively movable, the second die is secured to the movable platen front-part, the movable platen rear and front parts co-operate to form a fluid-pressure chamber whereby, upon fluid being admitted to said chamber, the two movable platen-parts are forced apart, and there are provided mechanical elements which retain the movable platen rearpart in its forward position, and at least a locking means disposed between the movable platen front and rear parts and movable, whereby to retain said movable platen two parts in their relatively spaced-apart positions and so provide a mechanical lock against movement apart of the two dies. The movable die platen comprises two parts 4, 7, the part 4 carrying the die 3 and forming a piston 15 which engages in a cylinder 16 in the part 7 to form a pressurechamber 17 to which pressure-fluid may be fed through a pipe 18. Wedges 19 between the parts 4, 7 may be moved to open the parts or allow them to move towards each other, by double-acting pistons 20. The assembly is moved forward to the die-closing position by a piston 28 acting through links 26 and arms 25 pivoted to the rear-part 7, until the arms 25 reach the end of guide-surfaces 32, when they spread apart and engage the faces 34, Fig. 3. Pressure-fluid is then fed to the chamber 17 to provide the locking-force on the dies 1 and 3. The wedges 19 are then drawn tightly between the parts 4, 7 by the pistons 20, so that the necessary locking-force between the dies is effected exclusively through mechanical elements, i.e. die 1, stationary platen 2, tie-rods 6, cross-head 5, arms 25, back-part 7, wedges 19, front-part 4, and die 3. Metal is injected by plunger 11. After injection, the dies are unlocked by slightly increasing pressure in the chamber 17 so that the wedges 19 may be withdrawn, the pressure in chamber 17 is then relieved, and the movable platen-assembly withdrawn by piston 28, Fig. 4, the part 4 being initially held stationary by the casting until constrained to move by bolts 24, whereupon the dies open and the casting is ejected. The wedges may be actuated electro-magnetically. In a modification, the wedges are located within the pressure-chamber 17. In a further modification, Fig. 8, the wedges are replaced by a screw-threaded ring 41b which is turned by a piston to press apart, or allow to move towards each other, the parts 4b and 7b. In a further modification, an externally-threaded ring is located within the pressure-chamber.