GB1317662A - Machine tool for the mass production of small workpieces - Google Patents

Abstract

1317662 Machine tool details; drilling; milling; straightening ALBE SA 6 July 1970 [10 April 1970] 32648/70 Headings B3B B3C B3E and B3K A machine for mass producing small metal articles comprises an indexable turntable 16 rotatable about a central shaft 5 and provided with a plurality of workstation in the form of discs 17 which are rotatable relative to the turntable 16 and which include workholding means, the workstation being spaced around the periphery of the turntable 16 and different working operations being carried out simultaneously at all the workstation. Co-axial with the shaft 5 is a stationary inner sleeve 194, an intermediate bush 18 rotatable with the turntable 16 and an outer stationary frame 193. The turntable 16 is rotated by means of a main motor 3 driving through a worm and wheel 4 to rotate the shaft 5. To the shaft is attached a cam 26 and a secondary turntable 9 which carries a cam 10. Bevel gears 7 are driven by the shaft 5 to rotate a group of peripheral cams 8 and a further group of axial cams 95 are rotated directly by the shaft 5. The two groups of cams 8, 95 operate tappets and levers to move a set of motor 98 driven chucks 99 at each workstation and to operate a wire or bar feed and straightening device as well as transferring finished and blank parts. Milling cutters are also rotated to cut a wire or bar into separate workpieces. The chucks 98, 99 are arranged above, below and peripherally of the turntable 16 within an arc of 200 degrees. Indexing When the cam 26 is rotated by the shaft 5 its cam surface actuates, at appropriate times in a cycle of operation, a plunger to engage a socket (45) (Fig. 6, not shown) with a pin (18<SP>1</SP>) attached to the rotatable bush 18. In sequence a further cam (19) (Figs. 2 and 3, not shown) actuates links 21, 22, 23 that oscillate an arm 24 about shaft 5. The arm 24 carries the socket (45) so that movement of the arm 24 in one direction rotates the turntable 16 and when the arm 24 is retracted the cam 26 actuates to disengage the socket (45) from the pin (18<SP>1</SP>). The arrangement includes spring override device (90) to limit the loads on the drive parts. When the turntable 16 is at a required position the cam 10 operates rods 14, 15 to lock the turntable and also each disc 17 relative to the turntable. The discs are rotated as required as the turntable 16 is indexed by gear teeth (32) (Figs. 12, 13, not shown) on each disc engaging with stationary gear segments (33). To assist acceleration and deceleration of the turntable during indexing the stationary inner sleeve 194 includes spring-biased radial pistons (101) (Figs. 17, 18, not shown) that act via rollers on internal scallops on the sleeve 18. Wire or bar feed and straightening In a vertical arrangement a wire or bar is fed through a straightener comprising a frame (145) (Fig. 28, not shown) which is rotated by a gear train (147) connected to the shaft 5, and a pair of spaced bushes (148) in between which is an eccentric bush (148). The frame (145) is also vertically reciprocated by means of a cam (149), tie-rod (150) and lever (151) at a speed lower than the feed of the wire or bar. The wire or bar is fed on to a movable abutment (160), gripped by jaws (155) and severed by a milling cutter (159). In a horizontal arrangement (Figs. 29, 30, not shown) the wire or bar is fed through two sets of rollers (166) (166<SP>1</SP>), and to a reciprocating gripper (167). The wire or bar is severed by a milling cutter 173. Blanks transferring Workpieces are held in a holder (169) (Fig. 31, not shown) of the discs 17 and removed therefrom by an element (180) having two pairs of spring loaded jaws spaced 90 degrees apart. The element 180 is mounted on the end of a rotatable and reciprocable member 176 so as to be able to grip a finished workpiece (187) in the holder (169) and also a new workpiece, to remove the finished workpiece from the holder (169) and to be rotated 90 degrees to place the new workpiece in the holder and release the finished workpiece. Chuck mountings and feed (Figs. 22-27, not shown). The peripherally mounted chuck is mounted on slide (130) (Fig. 24) for horizontal movement, the slide being mounted for vertical movement on bar guides (135). The horizontal movement is by a push-rod operated lever (132); the vertical by means of a lever (136). The vertically mounted chuck (Figs. 25, 27) is also moved by push-rod operated levers. The chuck is laterally adjustable by being mounted eccentrically in a sleeve which is rotatable by a gear (137) which is rotated by a rack and pinion drive (138), (139), (141). The chuck may also be mounted on balls in the said sleeve to allow longitudinal movement (Fig. 22, not shown). Main drive and control The main motor 3 may be supplemented by a secondary motor (31) (Fig. 14, not shown) to allow different speeds to be obtained. Each motor drives the worm and wheel 4 through selectable electromagnetic couplings (28), (30) and an electromagnetic brake (29) is provided. One of the cams of group 8 can select a potentiometer (54) or (55) (Fig. 16, not shown) for a required speed. The motor control includes a tachometer generator which when a motor (52) is being dynamically braked from a high to a lower speed produces a potential which is compared with the inserted potentiometer. The control circuit includes a thyratron-transistor bridge (65), and a braking resistor 59.