Patent GB-143523-A (GB)
Title: Improvements in relieving-lathes
IPC: B23B5/42
Filed: 1920-05-17
Abstract: 143,523. Pratt & Whitney Co., (Assignees of Muller, F.). Dec. 30, 1916, [Convention date]. Lathes. - In a lathe for backing-off reamers, taps, and other metal-working cutters &c., the tool-slide carrier 54 is pivotally mounted on the saddle 55, so that the slide 53 can be set at any desired angle, and the slide 53 is given a backing- off movement of variable frequency and amplitude through positively-driven cam and lever devices actuated by gearing from the main shaft 12 independently of the lathe spindle. The slide 53 has. also hand or automatic feed mechanism with automatic stopping-devices to determine the depth of cut, the operating-means for the slide 53 being, in both cases, unaffected in their operation by its angular position. Means carrying the tailstock 3, for driving and mounting the lathe spindle 1, for operating a collet 50 to clamp the work, and also a stop 51 to position the work, are provided. Framing.-In order to mount the tailstock 3 so as to clear the tool slide and yet be close up to the work, it is carried by an overhead bar 27, preferably of triangular cross-section and with recessed sides, carried at one end by a removable bracket 31 adjustable on the bed 1, and at the other end by detachable supports 28 on the headstock 4. Tailstocks.-The tailstock 3 may be constructed in two parts 36, 37, clamped on to the bar 27 by bolts 38, 40, and having a clamping-bolt 45 to hold the sleeve 41 in its adjusted position. Headstocks; driving machine spindle.-The lathe spindle 1 is driven by high or low speed worm gear 10, 11 driven from the shaft 12 and coupled to the spindle 1 through a sliding clutch member 21 actuated by a hand-lever with spring- controlled locking-pin. Feed-motions, tool and saddle; reversing- mechanism.-The backing-off motion is given to the slide 53 through a bell-crank lever 54 pivoted on a stud 59 and having a roller 67 on one arm 60 engaging the cam 61 mounted on a pin 63 concentric with the axis about which the slide-carrier 54 is adjustable, and driven through worm gearing 65, a shaft 66, bevel-gear 81, and change-speed gear 90 &c. from the shaft 12. The other arm of the lever 54 is in two parts slidably connected, the part 69 being set by an adjusting-screw 73 in such position that segmental projections 70 on the part 69, engaging a transverse recess 71 in a slidipg member 68 on the slide 53, are sufficiently eccentric to the stud 59 to impart the desired amount of backing-off movement to the tool-slide 53. An adjustable spring 76 assists the cam 61 in giving the slide 53 a sharp return motion. The automatic feed for the slide 53 to feed the tool against the work for the requisite depth of cut, may comprise a screw 118 slidably coupled to a shaft 120 having spring-controlled frictional driving-connexion with a worm-wheel 123, worm 124, and shaft 126. This shaft may be operated by the hand-wheel 153 through screw gear, or automatically by ratchet mechanism operated through oscillating toothed gears 139, 138, toothed ring 137, gears 140, 143, and shaft 144, on which is a pinion 145 engaging a rack-bar 147 adjustably coupled to a cam-operated lever 149, to impart to the tool the desired rate of feed. In an alternative arrangement, the shaft 126 is actuated by a ratchet operated through a sliding bar engaging the backing-off lever 69. An adjustable stop 157, mounted on the disk 125, forms part of the spring- controlled frictional drive, and the feed is thus stopped. A handle 161 may operate a cam shaft to put the ratchet drive out of engagement, and simultaneously retract a stop-bar 159, thus allowing the hand-wheel 153 to operate the slide freely in either direction. The saddle 55 may be moved by rack-and-pinion actuated by hand-wheel 97 or by a lead-screw 98 driven by change-speed and reversing gearing of ordinary type put into or out of action by hand-lever 104. Gauging-devices. - A stop-bar 51 is adjustably clamped in position to determine the position of the work in the jaws of the collet 50. Chucks.-The collet 50 is opened and closed by the screwed engagement between the collet 50 and the tubular member 48 rotated by hand-wheel 49.