GB771846A - Improvements in or relating to tandem toggle presses - Google Patents

Abstract

771,846. Casting - machines; moulds. NATIONAL LEAD CO. May 2, 1955, No. 12707/55. Class 83 (1). [Also in Group V] A toggle-press casting-machine comprises, Figs. 2 and 3, a stationary plate 12 and a sliding plate 14 (between which the mould-sections 50 are forced together), a fixed end-plate 16, a slidable centre-frame 18, toggle-linkage 20 operated by a crosshead 22 for moving the plate 14, and toggle-linkage 24 operated by a crosshead 26 for moving the frame 18. Linkage 20 connects plate 14 to frame 18, and linkage 24 connects frame 18 to fixed end-plate 16. The crossheads are moved by a hydraulicallyoperated rod 30 which is secured at its righthand end to crosshead 20 but is slidably disposed in crosshead 26. Two lost-motion collars 32, 34 are fixed to rod 30. When rod 30 moves to the left from the closed position shown in Figs. 2 and 3, the rod moves crosshead 22 to the left without, at first, moving crosshead 26. Rod 30 slides idly through 26 until collar 34 reaches 26, whereupon 26 also moves left. This leftward movement of crosshead 26 occurs before crosshead 22 reaches frame 18. The final, open position is shown in Fig. 8. On the closing movement, crosshead 22 again moves before crosshead 26 moves, the latter remaining stationary until it is taken up by the collar 32, and both toggles reach the closed position of Fig. 2 simultaneously. Details. The plate 14 and frame 18 slide on four tie-rods 40. The crossheads slide on rods 70 secured at their forward ends to plate 14. Plate 16 is adjustably locked on rods 40 by nuts 48, and to facilitate adjustment, it has rollers 58, 60 which run on rails 42. The plate 14 and frame 18 also have rollers 46. Plate 12 is fixed to the rails 42 at 44. The press shown is a cold-chamber die-casting machine having a hydraulic shot-cylinder 74 secured to the rails by pedestal 75. Modifications. (1) (Figs. 4 and 6, not shown). The frame 18 may be locked in advanced position on the rods 40, the collar 34 being removed and the toggle 24 being fixed, this giving a short mould-opening stroke. A minimum-stroke may be obtained by limiting the travel of plate 14 by stops on the rods 70; (2) (Figs. 5 and 7, not shown). An intermediate mould-opening stroke may be obtained by interposing stops on the rods 70 between plate 16 and crosshead 26. (3) Each of the toggles shown may be duplicated.