Cutoff press

In a machine for successively treating tubular stock traveling along a horizontal path including a frame having a bed portion and a head portion between which the stock travels, a ram supported by said head portion and overlying said bed portion, slide rails on the bed portion and the ram parallel to said path for slidably receiving a die set, and said die set having work engaging parts actuable by movement of said ram to perform an operation on said stock, the improvement in means for driving the ram through a stock treatment cycle in a downward work stroke and an upward return stroke, which drive means comprises means for mounting the ram for vertical movement only, a pair of horizontally spaced apart crankshafts rotatably supported by the head portion, means driving the crankshafts in opposite directions, said crankshafts having cranks the centers of which are eccentric to the axes of crankshaft rotation, connecting rods connected at their upper ends to the cranks and at their lower ends to spaced apart wrist pins carried by said ram, and said wrist pin centers being spaced laterally from a plane extending vertically from the axes of crankshaft rotation, said laterally spaced wrist pins functioning to commence the downward acceleration of said ram prior to said crank reaching top-dead-center of said crank rotation and to direct the entire force acting on said connecting rods substantially downwardly during said cutoff cycle therby minimizing lateral ram instability.

In a cutoff press for segmentally cutting tube traveling along a rectilinear path including a frame having a bed portion and a head portion between which the tube travels, a ram supported by said head portion in overlying relationship to said bed portion for rectilinear movement only perpendicular to said path, slide rails on the bed portion and the ram parallel to said path for slidably receiving a die set, and said die set having a shearing mechanism actuatable by movement of said ram to cut the tube, the improvement in means for driving the ram through a cutoff cycle having a cutting stroke and a return stroke, which drive means comprises a pair of spaced apart crankshafts rotatably supported by the head portion, the axes of said crankshafts being parallel to each other and in a common plane extending parallel to said path, means driving the crankshafts in timed relation in opposite directions, said crankshafts having cranks the centers of which are eccentric to the axes of crankshaft rotation, connecting rods connected at their upper ends to the cranks and at their lower ends to spaced apart wrist pins carried by said ram, the axes of the wrist pins being parallel to each other and the axes of crankshaft rotation and in a common plane parallel to the path, and said wrist pin axes being spaced outwardly from planes extending perpendicular to the path and in the axes of crankshaft rotation such that the attitude of the connecting rods during the cutting stroke is substantially perpendicular to the path, said laterally spaced wrist pins functioning to commence the downward acceleration of said ram prior to said crank reaching top-dead-center of said crank rotation and to direct the entire force acting on said connecting rods substantially downwardly during said cutoff cycle thereby minimizing lateral ram instability.