| 摘要 |
1,120,812. Feed drive mechanisms; machine tool details &c. WILLIAM ASQUITH Ltd. 5 Nov., 1965 [6 Nov., 1964], No. 45270/64. Headings B3B and B3C. [Also in Divisions F1 and F2] In a feed drive for the tool of a machine tool, for example, a drill spindle of a drilling machine, a hydrostatic bearing 16 is used to sense the engagement of the tool with the workpiece and effect a change over from a rapid feed to a slower operating feed. The feed drive includes a worm 14 on a shaft 15 connected to a high speed hydraulic motor 22 at one end and a magnetic clutch 23 at the other end for engaging with the slower feed drive. When the tool engages the workpiece the worm 14 is moved axially along the shaft 15 to either increase the pressure (Fig. 2 not shown) or decrease the pressure (Figs. 4 and 5 not shown) in the hydrostatic bearing 16. This change of pressure is transmitted to a blocking diaphragm valve 24 or blocking spool valve (58) (Figs. 4 and 5 not shown), which operate to block the output from the hydraulic motor 22, (53) which is by-passed via a relief valve 36, (75). When the blocking valves 24 or (88) operate, a micro-switch is operated to effect take-up, via the magnetic clutch 23, of the slower feed drive. Solenoid operated valves, motors, pumps and filters are used in the hydraulic circuitry. A timing device may be used with the said micro-switch to permit the deceleration of the hydraulic motor. To permit the worm 14 to declerate more rapidly than the feed shaft the worm is mounted on a fine screw thread (41) (Fig. 2 not shown), and energy is absorbed in a spring (19). |
