GB810309A - Improvements in and relating to a machine-tool - Google Patents

Abstract

810,309. Boring &c. machine details. SOC. GENEVOISE D'INSTRUMENTS DE PHYSIQUE. Nov. 25, 1955 [Dec. 8, 1954], No. 33805/55. Class 83 (3). [Also in Group XXIX] In a boring &c. machine wherein a verticallyadjustable beam 9 supported near each end by a piston 14, 15 and along which a tool-carrying headstock 12 is movable horizontally, means h1, h2, 36, 36 are provided for adjusting the pressure beneath the pistons in accordance with the position of the headstock. The pistons are supported in cylinders 16, 17 fed with oil from continuously-rotary pumps a, d, further pumps b, c delivering oil beneath the pistons only when the beam is raised, under the control of screws 24 rotatable in nuts 26 in the beam, by an electric motor (not shown). The pressure in the cylinders is adjusted through valves h1, h2 which are subjected to a variable-pressure from circuits V1, V2 controlled by the headstock, the valves controlling the escape of pressure between the pumps a, d and cylinders and hence the pressure in the cylinders. A further, highpressure, pump e supplies oil through a line t to a pair of valves 36, Fig. 3, on the beam, connected in parallel, and each controlling the pressure in one of the circuits V1, V2 respectively. Each valve is pressed against its adjustable operating-lever 33 by a spring 38, and has diagonally-opposite chamfers 44, 45 which afford a lead into the associated circuit V1 or V2 and out to exhaust, the latter through one of the ports 39 in the valve-housing 37, which are interconnected by an annular channel in the bore of the housing, and through a return-pipe 46 in the valve-box 27. The operating lever 33 is pressed against a follower 20, and the latter against one of a pair of oppositely-inclined plate-cams 22 on the headstock 12, by a plunger 35. Adjustment of the headstock towards the left-hand end of the beam causes the follower 20 for piston 16 to rise and the associated valve 36 to fall, thus increasing the valve-opening 39 to circuit V1 and reducing the valve openings at 45 and h1 to exhaust. A corresponding, opposite movement of valve h2 occurs, reducing the pressure in cylinder 17. Free barrier-pistons in cylinders m1, m2 prevent the transmission of heat between the oil passing through the pumps and that in cylinders 16, 17, valves in the pistons opening, to compensate for loss of oil, when the pistons reach the ends of the cylinders. The beam of a single-column, horizontal boring-machine (Fig. 4, not shown), may be balanced in the same manner.