| 摘要 |
PURPOSE:To prevent the breakdown of a hydraulic cylinder for driving a powder-molding die, by providing a drain passage having a valve plate of known strength against rupture, in front of a relief valve in a hydraulic circuit including the hydraulic cylinder, to take secure countermeasures against abnormally high pressure caused in the cylinder. CONSTITUTION:A branch passage 11 fitted with a relief valve 10 is connected to a passage 9 for supplying high-pressure oil from a pump 14 to a hydrauic cylinder 7 or draining the high-pressure oil out of the cylinder. A drain passage 13 extending to an oil tank 12 is onnected to the branch passage 11. The basic body 17 of a protector is provided in the halfway part of the branch passage 11. A valve element 18 made of metal of accurately determined strength against rupture is secured on the basic body 17. A fluid 20 for operating a limit switch 19 is connected to the drain passage 13 extending to the valve element 18. A spherical valve 23, which is energized by a spring 22 in a direction to close, is provided in the drain passage 13. When abnormally high pressure is caused, the valve plate 18 is ruptured to operate the limit switch 19 to stop a whole equipment. |
