Patent GB-321812-A (GB)
Title: Improvements relating to automatic turning lathes
IPC: B23B9/08
Filed: 1928-11-02
Abstract: 321,812. Renold, Ltd., H., and Renshaw, A. Nov. 2, 1928. Lathes. - In automatic turning-lathes wherein workpieces are held in chucks on parallel rotary spindles facing the same way and wherein each work-piece after being turned in one chuck is transferred to another chuck in a reversed position for the turning of its opposite end or side, a work-transfer member moves in a, plane perpendicular to the axes of the chucks and simultaneously rotates about an axis in this plane and transverse to the line joining the two working positions. The blanks are transferred from a hopper to a chuck, pushed axially into the chuck, operated upon by cutting tools, ejected from the chuck and transferred to a second chuck, inserted therein in a reversed position, operated upon at the opposite end by further cutting tools and finally ejected into a receptacle. More than two chuck spindles may be provided for performing further operations. As applied to a lathe for producing bushes for chains of the form shown in Fig. 5 from cup-shaped blanks a, Fig. 3, an electric motor is connected by a belt to pulleys 1<a>, Fig. 1, which drive the work-spindles C, E, by means of a belt 3, Figs. 1 and 9, passing over pulleys on the spindles and an adjustable tensioning pulley 6. The cam-shatt 7, which carries all the cams for controlling the tool and work-feeding devices, is rotated through a belt 16 in a casing 17 from a shaft 13 bevel geared to a shaft 10 which is driven by change wheels 9 from the pulleys 1<a>. A sleeve 25, Fig. 9, worm-geared to the cam-shaft at 26, is clutched to the belt pulley 15 when the machine is working normally but may be disconnected and rotated by hand for setting-up the machine. The pulley is rotatably mounted by ball bearings 19 on a normally stationary shaft 20 and has clutch teeth 23 which are engaged, bv axial movement of the shaft 20, with teeth on the sleeve 25. For hand rotation of the cam-shaft the shaft 20 is pushed to the left in Fig. 9 thereby disconnecting the teeth 23 and engaging teeth 31 on a collar 32 attached to the shaft with teeth on the opposite end of the sleeve 25. When the camshaft is rotated by power, teeth 34 on a collar 35 attached to the shaft 20 engage stationary teeth 36 to prevent this shaft from rotating. A blank is first inserted with the open end protruding in the spindle C and simultaneously a partially completed blank is inserted with the closed end protruding in the spindle E. Both blanks are operated upon simultaneously to cut off and trim the ends by circular tools 78. 81, Fig. 9, carried by holders 79, 80 on a slide 88<A> which is depressed against a spring 89 by a lever 86, connecting rod 85 and a cam 82, the lower end of the connecting rod being guided by a link 84 pivoted at 84<A> to the machine frame. An internal taper d and an external neck c, Fig. 5, are formed on the blanks by reamers 90, 95, Fig. 8, and circular tools 90<A>, 95<A> carried by a slide 91 which is reciprocated by a lever 93 and a cam 92 against a spring. Alternatively, the neck turning tools 90<A>, 95<A> may be carried by the vertical slide 88<A>. The machine may be used for turning and boring tubular or bar stock, in which case the stock is fed intermittently so as to cause its end to abut against a shoulder in the collet of the first spindle, this end of the work is cut off and the blank so formed is then transferred to the second spindle. The chucks are of ordinary construction and are operated from a cam on the shaft 7. Blanks, transferring.-The rough blanks a, Fig. 3 are supplied to a hopper 38, Figs. 1 and 10 and are transferred to a tubular shoot B by means of picker arms 39 mounted on a shaft rotated by a pulley 30 from the cam-shaft 7. The arms 39 are split longitudinally and accommodate pivoted members 43 carrying rollers 44 which are maintained in contact with a stationary cam 45 by springs 46. Projections 47 on the ends of the members 43 enter the cavities of the blanks and recede to allow the blanks to remain in the shoot when the rollers 44 leave the high part of the cam 45. The shoot is split at 48 to allow the arms 39 to pass and the arms are frictionally driven at a speed greater than that required to supply the machine with blanks, the rotation of the arms being thus intermittent. The lowermost blank a<1>, Fig. 9, in the shoot B is received by spring fingers 51 on a plunger 49 which is reciprocated axially by a cam 52, lever 54 and a spring 54<A>. A pin 58 in the plunger rides in a helical slot 59 of the bracket 50 through which it slides in order to rotate the blank through 90‹ and place it in front of the chuck spindle C with the closed end towards the chuck. The blank is inserted by an injector 60, Fig. 8, on a curved arm 62 having a cylindrical shank 64 provided with a cam slot 75 engaging a fixed pin 73. A similar injector 61 having a shank 65 is provided for inserting a partly formed blank in the chuck E from a transferring member, the two shanks being slidable through a fixed block 66 by means of a cam 67, lever 68, slide 70 and springs 71. The cam slots 75, 76 give the injectors the required parallel and oscillatory movements for inserting the blanks in the chucks. The blanks engage combined stops and ejector bars 101, 102, Figs. 6 and 8, in the chucks, and after the first blank has been operated upon the ejector is actuated by a slide 98, lever 97 and cam to push the blank between the spring fingers 103 of the transferring member D. Simultaneously, the finished blank is ejected from the chuck 57 into a shoot F, Fig. 9, attached to the member D and thence into a receptacle. The transferring member D is oscillated about a boss 104 on the machine frame by means of a cam 117 so as to bring the fingers 103 opposite the chuck 77 for receiving a partly formed blank, then opposite the chuck 57 for insertion of the blank therein by the injector 61, and finally into a central position as shown in Figs. 6 and 9 to allow the tools to operate. The fingers 103 are carried by a spindle 110 rotatable in the member D by means of a bevel pinion 111 thereon engaging a fixed arcuate rack 105 so that the blank will be rotated through 180‹ in passing from chuck 77 to chuck 57. To ensure an accurate rotation of the shaft 110 the pinion 111 is loose on the shaft but is secured to a bracket 115, Fig. 7, carrying springs 113 which engage an arm 112 secured to the shaft. At each end of its stroke the arm 112 engages an, adjustable stop 116 thus ensuring the correct position of the blank relatively to the chuck, irrespective of any further movement of the member D. The oscillatory movements of the member D about its pivot 104 are controlled accurately so as to position the fingers exactly in front of the chucks by means of fixed adjustable stops 107, 108, Fig. 9, and a web 109 on the member. The cam 117 acts on a roller 118 on a lever 119 pivoted at 55 and pulled to the right in Fig. 9 by a spring 120. A second spring 123 is connected to the lever at 122 and at 124 to a link 125 pivoted at 126 to the transfer member D. When the web engages the stop 107 the roller 118 is held slightly off the cam 117 and when the stop 108 is encountered, the cam causes a pin 128 on the lever to move along a slot 127 in the link 125 and compress the spring 123, thus allowing for an excess lift on the cam. In an alternative construction the transfer member D reciprocates along guides perpendicular to the chuck axes instead of oscillating and the spindle 110 then carries a spur wheel rolling along a straight rack. The reciprocating member could then carry more than one spindle 110 for transferring blanks between more than two working spindles. According to the Provisional Specification the shanks 69, 65 of the injectors may be feathered in pinions which are oscillated by a cam-actuated rack to swing the injectors in and out of line with the chucks.