| 摘要 |
980,845. Machine tool details. CINCINNATI MILLING MACHINE CO. Aug. 8,. 1963 [Jan. 15, 1963], No. 31309/63. Heading B3B. [Also in Division G4] In a device for setting the angular position of a member 10, e.g. a machine tool worktable, a coarse position motor 44 rotates the member 10 until a coarse position signal is produced, when fine position signals are also produced and cause a fine position motor 82 to rotate the member 10 by an amount corresponding to the fine position signals. A drum 34 (Fig. 1), which rotates with a worktable 10, has rows of four extendable dogs, e.g. 36, 38, 40, 42, at 4 degrees intervals around its circumference which are set manually in accordance with the required stopping positions of the table 10. To move from one position to the next, a switch is closed (e.g. manually) thus causing a fluiddrive motor 44 to drive the table 10 (and drum 34), via gearing 54, 32 &c. When a row of dogs having dog 42 extended comes opposite a row of switches 1LS, 2LS, 3LS, 4LS, switch 4LS is closed to stop motor 44. Coarse positioning to 4 degrees having thus been accomplished, fine positioning to ¢ degree is done as follows. The dogs 36, 38, 40 actuate a selection of the switches 1LS, 2LS, 3LS to supply the required fine position increment in binary coded form and energize a selection of solenoids 1SOL, 2SOL, 3SOL (Fig. 3) which control valves 110, 136, so as to connect one of eight ports 101 . . . 108 in a cylinder of fine position motor 82 to a pressure return line 68. A pressure supply line 62 is permanently connected to both sides of a piston 86 in the cylinder, so the piston 86 takes up one of eight axial positions and performs the fine positioning via an arm 76, a rack 74 and a gear-wheel 30 rigid with table 10. During coarse positioning, the rack 74 is held away from gear-wheel 30 by a pressure motor 78. In being moved back into mesh with gear 30, rack 74 positions the latter to within ¢ degree preliminary to fine positioning. Disengagement of rack 74 and also zeroizing of fine position motor 82 immediately precede coarse positioning. |
