Patent GB-551046-A (GB)
Title: Improvements in or relating to automatic screw making machinery
IPC: B23G1/04
Filed: 1941-06-09
Abstract: 551,046. Lathes. TELCO, P., and LOWEN, C. G. June 9, 1941, No. 7281. [Class 83 (iii)] In an automatic screw machine wire stock is fed through a chuck into a screwing die, a rotary cutting tool being employed for nicking the screw head and the screw being parted after the nicking operation. In Figs. 1 and 1A wire stock, (not shown), is fed through a rotary spindle 9 mounted in bearings 10, 11 and through a chuck 1 having adjustable stock-engaging free rollers which impart rotation to the work but permit the axial movement thereof with minimum friction. A screwing die 2 mounted on the front of the chuck-casing is normally rotated by and at the same speed as the work but may be arrested by a push-rod 5 operated by a cam 6 on a shaft 7 so that the work is drawn through the die and screwed. When the required length of thread has been cut the plunger is withdrawn so that the die again rotates with the work. The spindle 9 and the chuck are rotated by chain gearing 12, 13 from a main shaft 14 driven by a self-contained motor or by a pulley 18. The cam shaft 7 is driven from the main shaft through change gearing 19, 24. Just before or after the forward movement of the stock is arrested the end is nicked by a rotary slotting saw which also rotates about the work axis at the same speed as the work. Preferably the nicking is effected after the work is arrested and the saw fed into the work to the required depth. The saw 34, Fig. 4, is mounted on a transverse spindle carried by a bracket 32 secured to a shaft 29 driven from the mainshaft by chain gearing, 27, 28. The saw spindle carries a bevel gear 35 engaging a stationary bevel gear 36 on the bearing 30, thus rotating the saw on its own axis. In a modification the wheel 36 may be driven oppositely from the shaft 29 so as to rotate the saw at higher speed. In order to feed the saw a taper cam 37 is formed on a push-rod operated through a rocker 50 by a cam 38 on the cam shaft. The cam 37 engages a hardened plate 42 on the saw carriage 43 to impart the feed movement. The carriage 43 is in two parts connected by springs 48, the part 43a being adjustable by a screw 45 to adjust the saw for screws of different lengths and the part 43 being operated by the cam for the saw feed. The bracket 32 may be fitted with a guide plate 51 to steady the end of the work. In some cases the depth of cut may be limited by a stop on the saw carrier engaging the work. After slotting, the work is parted off by a rotary or non- rotary parting tool. In one form a tool 53 is carried by a bracket 54 on a push rod 56 actuated by a cam 57 on the cam shaft. If necessary the speed of rotation of the work may be temporarily increased during parting-off. For this purpose a pulley 59 on the work spindle is driven from a large pulley 60 which is normally loose on the shaft 14 but may be clutched thereto by a clutch 61 operated through a lever 64 and link 63 from the push rod 56 so that the clutch is engaged to speed up the work just before the parting tool operates. To permit this high spindle-speed the sprocket 12 is fitted with a free-wheel. When cutting fine threaded screws a subsidiary die or screwed sleeve may be arranged in front of the main die to relieve the latter from the end drag caused in drawing the stock therethrough. In a modification, Fig. 7, the stock does not rotate and is fed by rollers 3 through a chuck casing 70 carrying the screwing die which is intermittently rotated, to screw the work, by a sprocket 69 driven from a sprocket 68 which may be locked to the main shaft by a clutch 74 operated by a cam 75 on the cam shaft acting through a lever 76. The saw 34 rotates only on its own axis and is driven by a pulley driving the bevel gear 36. A rotary parting-off tool is employed and is mounted on a bracket 82. This tool comprises a casing 83, Fig. 8, driven from a pulley 78 locked to the main shaft by a clutch 79 operated by a cam 80 and lever 81. The casing encloses an inner rotatable part 85 fitted with guides for the parting tool 86 which is normally retracted by a spring. A cam plate 89 on the casing engages a pin 90 on the tool to impart rotation thereto and also to cam the tool inwardly to effect the parting-off. The screw is supported during this operation by a bush 92. In another modification, the parting tool is moved into the work by the centrifugal force of a. weight 95, Fig. 10. Other modified forms of centrifugally-operated parting tools are described.