Abstract: In a gate valve having a rectangular gate, generation of flection at opposite end portions due to bending moment applied to the gate is suppressed easily. For this purpose, in the gate valve in which a central portion of a longer side of the rectangular gate is mounted to a tip end of a shaft operated by driving of a cylinder device and the gate is pressed against a valve seat provided around a rectangular valve opening by tilting the shaft after the gate is moved to a position facing the valve opening by movement of the shaft by driving of the cylinder device, the gate is formed to have an uneven wall thickness including a large thickness in a vicinity of a fulcrum portion connected to the shaft and a small thickness on each of opposite end portion sides.

Abstract: A gate 3 for opening and closing an opening 2 of a chamber 1 is fixed to a top end of an arm 7 swung between a position facing the opening and a retreating position on the side thereof. A base end of the arm 7 is supported by an output shaft 10 of a fluid pressure cylinder 8 driven in parallel with a direction in which the gate comes into contact with and is separated from the opening 2, and a cam follower 12 fit in a guide groove 14 of a machine frame 6 is provided at the base end of the arm 7. The guide groove is formed by an axial-direction groove 14a for carrying the gate 3 at the position facing the opening 2 and then moving it when the gate is located at a position in the vicinity of the opening of the chamber 1, and a slant-periphery direction groove 14b connected thereto for retreating the gate to the side of the opening.

Abstract: A high vacuum valve prevents the transfer of heat from a valve plug of a valve via a valve shaft to a low temperature portion. The high vacuum valve is constructed such that the valve plug arrives at a position opposed to a valve seat in accordance with rectilinear motion of the valve shaft and then the valve plug is pressed against the valve seat in accordance with swinging motion of the valve shaft to close the valve.

Abstract: A gate valve is disclosed comprising an elevatable lever member connected to a piston rod, a displacement member for making up and down movements integrally with the lever member and being tiltably disposed about supporting rollers acting as a pivot point or fulcrum at an end position of displacement, spring members interveningly disposed between the lever member and the displacement member, pin members fixed into side surfaces of the lever member, and engaging grooves formed in side surfaces of the displacement member and engaging with the pin members.

Abstract: In a gate valve having a rectangular gate, generation of flection &dgr; at opposite end portions due to bending moment applied to the gate is suppressed easily. For this purpose, in the gate valve in which a central portion of a longer side of the rectangular gate 5 is mounted to a tip end of a shaft 6 operated by driving of a cylinder device 2 and the gate 5 is pressed against a valve seat 8 provided around a rectangular valve opening 7 by tilting the shaft 6 after the gate 5 is moved to a position facing the valve opening 7 by movement of the shaft 6 by driving of the cylinder device 2, the gate 5 is formed to have an uneven wall thickness including a large thickness in a vicinity of a fulcrum portion connected to the shaft 6 and a small thickness on each of opposite end portion sides.

Abstract: A gate valve comprises a valve rod for making displacement in accordance with a driving action of a cylinder mechanism; a guide shaft for guiding the valve rod; a valve disk for opening/closing a passage in accordance with a displacement action of the valve rod; a rack connected to the valve rod, for making displacement integrally with the valve rod; a pinion rotatably supported by a casing, for meshing with the rack; and a pillow member connected to the valve disk and formed with a male thread for making engagement with a female thread formed on an inner circumferential surface of the pinion.

Abstract: A gate valve comprises a valve rod for making displacement in accordance with a driving action of a cylinder mechanism; a guide shaft for guiding the valve rod; a valve disk for opening/closing a passage in accordance with a displacement action of the valve rod; a rack connected to the valve rod, for making displacement integrally with the valve rod; a pinion rotatably supported by a casing, for meshing with the rack; and a pillow member connected to the valve disk and formed with a male thread for making engagement with a female thread formed on an inner circumferential surface of the pinion.

Abstract: A high-vacuum valve arranged to prevent conduction of heat from a valve element to a low-temperature part through a valve shaft. After the valve element has been moved to a position facing opposite to a valve seat by rectilinear motion of the valve shaft, the valve element is pressed against the valve seat to close the valve by pivotal motion of the valve shaft. A heater is provided in the valve shaft in close contact with it. Wiring is connected to the heater to supply it with electric power from outside the high-vacuum valve.

Abstract: A double-walled tube assembly has an elongate inner tube of thermoplastic resin, and an elongate extruded outer tube of thermoplastic resin including a plurality of ribs having a constant height longitudinally of the outer tube and extending over the entire length of the outer tube, the ribs projecting toward the center of the outer tube. The ribs have distal ends fused to the outer perpiheral surface of the inner tube over the entire length of the inner and outer tubes. The rib width is from 0.5 to 1.5 mm. To continuously manufacture the double-walled tube assembly, the pre-molded inner tube is fed to an extrusion molding machine having a cross-head die, and thermoplastic resin is extruded from the cross-head die into an elongate outer tube around the inner tube.