| 摘要 |
1,174,295. Power hammers. KOBE-STEEL Ltd. 14 March, 1967 [14 March, 1966], No. 11874/67. Heading B3H. A high-speed hammer comprises a ram 2 with a piston 4 in a cylinder 3 formed in the upper wall of a gas-pressure chamber 1 through which the ram passes, conduits 5, 6 connecting the upper part of the cylinder through a valve 7 to the chamber and crank drive 12 to raise the ram after impact and a drive for a cam 20 to operate the valve in timed relation with the movement of the ram. The ram has a spindle extension 8 with a head 9 above a supporting frame 10 which is connected to the crank drive by rods 13. The chamber 1 is formed in a movable frame 10a slidable in guides 10b of a fixed frame 10c. The movable frame is mounted on an air cushion 26. Hydraulic-operated stopper pistons 17 have piston-rods 14 which abut the movable frame 10a when the ram is raised by the supporting frame 10 to separate the forming dies 28. In operation the valve 7 is opened to allow the pressurized gas from the chamber to enter above the piston 4. Since the upper face of the piston is larger than its lower face the piston starts to descend until it emerges from the cylinder 3 whereupon the pressurized gas acts on the piston to cause it to descend at high speed, Fig. 2 (not shown). Since the area of the upper wall of the chamber 1 is greater than that of its lower wall the movable frame is oscillated as soon as the piston 4 emerges from the cylinder 3. The stopper piston-rods 14 remain retracted. After forming the supporting frame 10 is raised by the crank and abuts the head 9 to raise the ram. Just prior to this abutment the piston-rods 14 are moved to engage the movable frame 10g so that the dies 28 can be separated. When the piston 4 is fully within the cylinder 3, Fig. 4 (not shown), the valve is closed. The frame 10 is raised further by the cranks and the stopper units 16, 17 act as hydraulic cushions, Fig. 5 (not shown). The frame 10 is then lowered and the piston-rods 14 push the movable frame 10g downwards to its equilibrium position and the rods 14 are retracted. The hammer is now ready for a further cycle of operations. In an alternative embodiment, Fig. 8 (not shown), the stopper unit 16, 17 serves solely to limit the movement of the movable frame and separate hydraulic piston cylinder assemblies (29)-(31) are provided between the rod (13) and the supporting frame (10). These assemblies act as hydraulic cushions separate from the stopper unit. |
