Patent ID: 7493935
Filing Date: 2009-02-24
Classification: B22D

Abstract:
1. A cylinder device for screw core removal having an outward appearance as a single-rod type double-acting cylinder, comprising: a cylinder tube with an inside diameter thereof in a stroke segment of a piston portion of a piston and sleeve formed so that said piston portion is fit into said cylinder tube and slid in contact with said cylinder tube, and with an inside diameter thereof in a given segment in front of said stroke segment formed so that a sleeve portion of said piston and sleeve is fit into said cylinder tube and slid in contact with said cylinder tube; a rod including: a core having a male screw (hereinafter referred to as a “screw core”) installed consecutively and coaxially in a leading end portion of said rod, said rod having a male screw segment with a male screw formed therein in a location thereof separated from said screw core by a predetermined distance and a rear-end-side segment formed as an internal fitting portion for said sleeve portion of said piston and sleeve, said male screw segment having a same pitch as a screw pitch of said screw core, said rod having an axial hole formed therein, said axial hole extending from a rear-end surface of said internal fitting portion to a front position of said male screw segment, said rod having a first communicating hole and a second communicating hole formed therein, said first communicating hole communicating said axial hole with the front position of said male screw segment, said second communicating hole communicating said axial hole with a location of said internal fitting portion, said sleeve portion of said piston and sleeve not fitting over said location of said internal fitting portion in close contact with said internal fitting portion; a rod cover with a female hole formed therein, said female hole screwing together with said male screw segment of said rod and causing said rod to penetrate said rod cover in a screwed state; a head cover with a screw rod installed upright and fixed to an inner wall surface thereof on a first cylinder chamber side so that an axial center of said screw rod is directed in an axial center direction of said rod screwed together with said rod cover; said piston and sleeve comprising said piston portion and said sleeve portion each having a hollow cylindrical shape and being fit into said cylinder tube, said sleeve portion being installed coaxially and consecutively with said piston portion, said piston and sleeve including a screw mechanism installed inside said piston and sleeve on an inner peripheral side of said piston portion, said screw mechanism screwing together with said screw rod installed upright and fixed to said head cover, and said sleeve portion fitting over said rear-end-side segment of said rod; and a fitting and coupling mechanism formed of said rear-end-side segment of said rod and said sleeve portion of said piston and sleeve, said rear-end-side segment and said sleeve portion forming a sliding pair in an axial direction of the cylinder device, and said rear-end-side segment and said sleeve portion being engaged with each other in a peripheral direction of the cylinder device; the cylinder device further comprising: an oil supply port at a location thereof capable of supplying operating oil to a second cylinder chamber in front of said piston portion when said piston portion is in a forward limit position within said cylinder tube; and another oil supply port at a location thereof capable of supplying the operating oil to said first cylinder chamber to the rear of said piston portion when said piston portion is in a backward limit position within said cylinder tube.