Patent GB-440014-A (GB)
Title: Improvements in screw machines
IPC: B23G1/12
Filed: 1935-04-23
Abstract: 440,014. Lathes. TILTON, F. N., 82, Charter Oak Avenue, Hartford, Connecticut, U.S.A. April 23, 1935, No. 12234. [Class 83 (iii)] A machine for pointing and threading screw blanks has a rotatable turret 1 with blankreceiving recesses arranged therearound and a number of vertical spindles 10 which move axially to engage and rotate the blanks while they are threaded by loosely mounted rotary chasing cutters which are moved axially along the blanks. The turret rotates on a post 2 secured to a bed 3 which carries a pair of hollow columns 18 connected to an upper plate 16. The under side of the turret carries a number of plates, 16 in the form shown with sockets 6 which receive the heads of blanks fed down one or more shoots 7 from hoppers 8. The spindles 10 are fitted with means to rotate the blanks while they coact with the threading and pointing tools. At other parts of the travel, that is on the discharging and feeding sections, collars 19 on the spindles engage over an arcuate cam 20 to maintain the spindles in raised position. The spindles are held down at the working positions by spring-pressed buttons 12. The finished blanks are discharged by a finger 22 on a ring 23 secured to the post 2. Each of the spindles carries a pinion 25 driven from a central gear 26 on a shaft 27 driven through bevel gearing from pulleys 33. When the turret is locked the spindles are thus rapidly rotated from the central gear but when the turret is unlocked the spindle speed is reduced and the gearing acts as a differential mechanism to effect indexing to one of four positions determined by a pawl 35 and notches 36. The pawl is mounted on a lever 37 and is withdrawn by a cam 41 on a shaft 42 driven from the shaft 27 through gearing 54, vertical shaft 51, bevel gears 50, cam-shaft 48, vertical shaft 45, and gears 44. A shaft 63 driven from the gearing 54 carries a friction roller 61. When the turret is stationary the roller lies in one of the recesses 62 but when the turret revolves the roller engages the turret periphery to determine the speed of the indexing movement. The rotation of the turret is retarded just before locking, by a brake shoe 56, connected to a lever 58 by joint 57 and operated by a cam 60 on the shaft 42. The blanks are carried first to the pointing and then to the threading cutters. The circular pointing cutters 66, Fig. 8, have a concave periphery with oblique grooves of the required pitch and are loosely mounted on arbors 67 adjustably carried by brackets supported on screws 69 threading into a table 70 adjustably secured to a central shaft 73 moved axially by a cam 75. Each pointing cutter may coact with a work-supporting plate 76 or alternatively pairs of opposed pointing cutters may be used. In the form shown, four pointing-cutters are used, arranged to point four blanks simultaneously on vertical movement of table 70. The threading is effected by pairs of circular cutters 77, Fig. 12, which also rotate freely on their arbors and are mounted on posts 80 screwing into the table 70. During the vertical movement of the table four blanks previously pointed, are simultaneously threaded by the cutters 77. In some cases all the tools may be either pointing or threading cutters and the turret is indexed 180‹, eight blanks being either pointed or threaded simultaneously and then ejected and replaced by fresh blanks as the sockets move past the end of the supply shoot on the next 180‹ indexing movement. The pitch of the cutters may be such as to form either wood screws or machine screws. Lathe and like drivers.-The spindles 10 are fitted with centring sockets 111 and blades 11, Fig. 8, which rotate the blanks during the tooling operations.