Patent GB-752475-A (GB)
Title: Device for controlling hydraulic feed and rapid-return motions of slides in machine tools
IPC: B23Q5/26
Filed: 1954-03-17
Abstract: 752,475. Lathe details. FISCHER AKT.- GES., G. March 17, 1954 [April 2, 1953], No. 7767/54. Class 83 (3). A control device for hydraulic feed of lathe &c. slides, in which the feed may be dependent on the spindle speed, comprises two feed-screws rotated in opposite directions by the headstock &c. spindle and a control valve having two parts, one of which is carried by the slide and the other moved relatively to the first part by one or other of the feed screws to supply fluid to either side of a piston to move the slide.' A lathe slide 3 is movable longitudinally along guides 2 on a bed 1. A further slide 6 on the slide 3 supports a cross-slide 8 and tool-holder 9. The headstock spindle 10 drives, through a belt 30, a continuously-variable speed-change device 31 which in turn drives the two 'feed screws 34, 35 in opposite directions by the gears 32. The feed-screws are supported in fixed bearings 33 in the frame 1 and in slidable bearings 36 in the slide 3: The latter is moved by a piston and cylinder 28, 25, the piston being anchored to the . frame 1 at 71. Pressure fluid is drawn from a tank 11 in the slide by a pump 12, a relief-valve 15 being provided. The fluid is delivered by a line 14b to the control valve 37 from whence it may be directed to either side of the piston 28 through lines 26, 27. The control valve comprises a first sleeve-part 38 secured within the housing 37, which is fixed to the slide 3 and a second piston-part 39 movable by three separate means. The first of these, to give a feed dependent upon the spindle-speed, comprises a crosshead 44 secured to an extension of the pistonpart 39 and carrying a pair of worm-wheels 47, 48, which are in constant mesh with the feed screws 34, 35, respectively. The worm-wheels rotate freely on spindles 46 on the crosshead, but may be braked by pressure fluid admitted through the lines 21, 22, controlled by a lever 18 of a valve 19. Thus, according to which of the worm-wheels is braked, the piston-part 39 is moved either to the right or left at a speed determined by the feed screws and the piston and cylinder for the slide feed is thus supplied with fluid at a controlled rate to move the slide. The control valve 17 can also be rotated by cams or stops arranged on the bed. The second means for moving the piston-part comprises another crosshead 51 connected by members 50 with a crosshead secured to the extended end of the piston-part. The crosshead 51 is held between fluid-pressure pistons 52, 53, which are moved, to give a high-speed forward or return movement of the slide, by moving the control lever 18 to lines 21 or 23. The third means comprises a handwheel 43 secured to a spindle 41 which passes through the wall of the slide 3 and has a helical groove 42 at its end which fits into the hollow interior of the pistonpart of the control valve 37. A pair of inwardly-directed pegs secured to the piston-part engage the helical grooves so that, with the spindle and feed-screws stationary, the valve may still be moved to give a feed movement to the slide. Similarly, movement of the pistonpart by the other means sets the handwheel 43 rotating through the helical grooves and this provides a damping means for sudden speedchanges of the valve.