| 摘要 |
1,108,402. Mechanical presses. HOUDAILLE INDUSTRIES Inc. 27 June, 1966 [25 June, 1965], No. 28645/66. Heading B5F. [Also in Division B3] A ram assembly comprises a reciprocable hollow cylinder 34 having an external ram surface 48, a hollow piston 49 in the cylinder arranged to be driven in power and return strokes, the piston having a chamber 51 and an opening with a valve seat 52 confronting and communicating with the interior of the cylinder, a valve 56 movably mounted in the cylinder to be engaged once during each power stroke to seal a quantity of liquid in the cylinder against flow into the piston chamber and to be disengaged from the piston once during each return stroke, means for continually urging the valve towards the opening and means for continually urging the cylinder in the direction of the return stroke. The piston 49 is reciprocated by an eccentric 17 keyed to a shaft 12. A plate cam 20 also secured to the shaft operates a switch 29 which controls a pneumatically operated clutch to stop the shaft 12 after one revolution. The valve 56 is biased upwardly by a spring 57 and its movement is limited by the head 59 of a screw 58 engaging a shoulder 60 of the piston. The cylinder 34 has a flange 35 which runs in an enlarged part 31 of the bore of the housing. Springs 38 bias the cylinder upwardly and its movement is limited by a stop-ring 33. Operation.-On the down stroke of the ram the piston 49 moves down in the cylinder 34 until the valve 56 engages the seating 52 and traps a quantity of fluid 40, the piston and cylinder thereafter moving down together in a working stroke. As the piston make. its return stroke the cylinder 34 follows it due to the pressure of the springs 38. |
