| 摘要 |
1,092,611. Change-speed control. J. R. SADIER. March 16, 1965 [March 16, 1964], No. 11037/65. Heading F2D. A constant mesh change-speed gear D is preceded by an expanding pulley gear E having a V-belt pulley 18 with a movable flange settable to four different speed settings by a pneumatic or, as shown, an hydraulic servomotor G. The arrangement may be used to drive the spindle C of a machine tool (Fig. 1) having a slide A fast with a cam plate 2 having fingers 3 actuating switches 4 in circuits 5, 8 controlling the expanding pulley gear and the constant-mesh gear. The cam plate may also control other operations of the machine tool. The constantmesh gear has gears 14-16 selectively clutchable to an output shaft 9 by electromagnetic clutches 14a16a, and the expanding pulley is controlled by the servomotor which has a piston fast axially with the movable flange 18a of the pulley 18. A pump 31 supplies liquid through a line 28 to each end of the servo cylinder, and four exhaust lines 33A-33D enter the cylinder at axially spaced locations and have valves 7A-7D controlled by the switches 4 of circuit 5. On one of the valves 7A-7D being opened a pressure differential is created across the servo piston which is thereby shifted until it blocks the opened exhaust line, so that the expanding pulley gear is set to the desired ratio. The rate at which the servo piston shifts is controlled by a regulating valve 38; for rapid shift valve 38 is by-passed by opening a valve 36. The regulated shift movement is used, for example, in machining a radial transverse surface interconnecting two different diameter cylindrical sections of a workpiece which is being machined, the arrangement ensuring that the cutting velocity of the tool is maintained substantially constant. In a modification the servomotor is connected to the movable pulley flange by a lever connected at an intermediate point to the flange and at one end to the servo piston and at its other end is adjustably pivoted to a link which is adjustably pivoted to a fixed frame. |
