GB958288A - Drawing press - Google Patents

Abstract

958,288. Cupping. L. SCHULER A.G. Oct. 13, 1961 [Oct. 22, 1960], No. 36802/61. Heading B3Q. A drawing press in which the driving crank or the driving eccentric is connected with the ram by a connecting rod and a further rod pivotally connected together to form a toggle joint, the hinge being deflectable by special drive means across the line connecting the crank and the ram for the purpose of modifying the simple harmonic motion generated by the crank by a supplementary motion is characterized in that a motion for the lateral deflection of the hinge differing from that which would be generated by guiding a rearward extension of the connecting rod beyond the crank along a circular path is impressed upon the toggle joint at a point located at a distance from the hinge which is less than twice the length of the connecting rod so that the latter forms a lever transmission amplifying said supplementary motion. In an embodiment one arm 4 of a toggle joint is pivoted at one end on the pin of the crank 2 of a crank-shaft 1 and at the other end 5 to the second arm 6 of the toggle joint which is attached to the ram 7, Fig. 1. Arm 4 is extended beyond its pivot 8 on the crank and pivotally attached to a link 13 the other end of which is articulated to the end of a two-armed lever 15, 16 working on a fixed fulcrum 17. The end 18 of the lever arm 16 is pivotally connected by a link 19 with the crank pin. The motion of the drawing ram can be varied by modifying the curve which defines the path of hinge 12. This curve can be varied by pivotally attaching link 19 to a different point on the crank or to a selected point on toggle arm 4 and its extension 9. A disc cam may be keyed to the crank-shaft for controlling the movement of the hinges 12 and 18. Link 19 may be driven by a separate crank 20 on the crank-shaft, Fig. 2. For driving a blank holder slide the two-armed lever 15, 16 is provided with a third lever arm 21 which is pivotally connected to a bell-crank lever 23, 24 by a link 22, Fig. 3. The arm 24 of the bell-crank lever is connected to a twoarmed lever 27, 28 by a link 26 and the arm 28 of the two armed lever is connected to the blank holder slide by a rod 29. This linkage ensures that the blank holder slide remains at rest from just before the drawing plunger contacts the blank until just after the plunger has been withdrawn. Fig. 4 shows a modification of the embodiment shown in Fig. 2 wherein at bottom dead centre of the ram levers 13 and 15 are fully extended. This ensures that the working pressure of the ram is taken up by the crank 12 in dead centre position and that at an earlier or later instant said pressure is transmitted to the fixed fulcrum 30 in virtue of levers 13 and 15 being relatively fully extended so that other members are relieved of this load.