| 摘要 |
934,615. Milling. CINCINNATI MILLING MACHINE CO. Feb. 15, 1962 [March 2, 1961], No. 5798/62. Class 83 (3). A machine tool comprises a primary servovalve which responds to a velocity input signal to control an hydraulic means for actuating a compensating hydraulic actuator for moving a secondary servovalve controlling a main hydraulic means for moving a load member, and a feedback connection from the main means to the primary valve to move the valve to a neutral position. Handwheels 12, 16 adjust the table 11 and a slide 15. The slide 15 carries a cutter slide 17 movable vertically by intergeared handles 18, 19. The slide carries a cylinder 25 co-operating with a piston 26 on a rod having ports 30 connected through passages in the rod to lines 36, 37 from the secondary valve 35. Mounted on the rod is a piston 40 in a compensating cylinder 39 connected to the primary valve 45. The table 11 also carries a screw 57 engaged by spring-pressed half-nuts in a slidable and rotatable member 54 connected to a plunger 49 engaging the valve 45. The member 54 is rotated through a gear 60 either by the hand wheel 12 or by an electric motor according to the setting of two clutches. The motor is driven by signals from a tape with a feedback control provided by a rack on the table. Thus, in operation, when the gear 60 is rotated to move the plunger 49 to the left, pressure is supplied to the left of the piston 40 moving the rod 27 to the right together with the table and the screw 57. The plunger 49 is thereby moved right to return the valve to its null position. However, as the piston 40 moves right it moves the valve 35 to the right thus supplying fluid to the right-hand side of the cylinder 25 to move the table to the right, which will cause the plunger 49 to shift the valve 45 towards the right and fluid will be directed to the right-hand side of the piston 40 to move the table 11 towards the left. After a two-fold cancelling motion, therefore, the table has moved right by a distance equal to the input signal to the plunger 49. For controlling the slide 17, the hand wheel 18 rotates a screw 89, Fig. 4, to displace a primary valve 92; this causes movement of a piston 96 to move the slide 17 and a nut 90 attached thereto, thereby returning the valve 92. At the same time the valve 85 is displaced to supply fluid to the piston 99. Thus, while the handle 18 is turned at a constant speed, the piston 99 is moved. Specifications 705,464 and 753,620 are referred to. |
