Patent GB-628662-A (GB)
Title: Improved screw-threading machine
IPC: B23G1/04
Filed: 1947-05-27
Abstract: 628,662. Screwing; die-heads. SOC. ANON. DES ACIERIES-CI-DEVANT G. FISCHER. May 27, 1947, No. 14099. Convention date, May 27, 1946. [Class 83 (iii)] A screwing-machine comprising a rotatable and axially-movable die-head 1, the chasers 4 of which are engaged by means provided on a cam disc rotatable relatively to the diehead and axially-movable therewith, the cam disc being provided with a hub 5 having a dog 14 engaging in a groove 16 of a bush 6 rotatable, but not axially movable, with the spindle 3 relatively to the hub 5, is characterized by a key 10 which is axially movable relative to the spindle 3 and engages in a skew groove 13 of the bush 6 for turning the latter relatively to the die-head 1 so as to rotate the cam disc further and thereby raise the chasers from the work upon completion of the cutting operation. The spindle 3 is given its rotational and axial movement by means of a driving shaft 20 to which is keyed a pinion 21 engaging a spur-wheel 22 coupled to the spindle 3 through a claw coupling 23, 24, the latter being engaged by the axial movement of a slip-ring 25 provided with a rack 28 which is engaged by a pinion 29 fixed to a shaft 30 rotatable by a hand lever 31. In operation, the hand lever 31 is rotated clockwise and after the claws of the coupling 23, 24 have been engaged, slip-ring 25 and spindle 3 are moved axially to screw-thread the work. When the desired length has been screwthreaded, a stop 43 on a thimble 38, adjustably mounted on the shaft 30, abuts a stop 44 on the hub of a spring-influenced arm 45, freely rotatable on the shaft 30, which is moved clockwise and thereby releases a spring-influenced lever 50, fixed to a shaft 51, to enable it to move counter-clockwise and cause a segmental gear 53 to move axially a grooved wheel 54 fixed to the key 10 and thereby raise the chasers from the work. The space 56 between the stops 43 and 44 can be adjusted so as to vary the stroke of the spindle 3 by adjusting the thimble 38 and the hub 32 of the hand lever 31 angularly relatively to each other. On rotating the hand lever 31 counter-clockwise, the key 10 is moved in the reverse direction by means of a lever 57 which acts on the lever 50 to restore it to its original position. The groove 16 is made either skew or parallel to the spindle 3 according as taper or parallel threads are to be cut. The key 10 may be disposed in a central bore of the spindle 3. Means, Figs. 4 and 5 (not shown), are provided for preventing the spindle 3 from being moved axially until the claws of coupling 23, 24, are in full mesh. In a modification, Fig. 8 (not shown), the wheel and segmental gear for moving the key axially of the spindle are replaced by a sleeve and slip-ring. In another modification, Figs. 9 to 11 (not shown), the two skew grooves in the bush are replaced by a single skew groove, and the chasers are raised from the work by moving the key away from the die-head. In a further modification, Fig. 12 (not shown), the spindle and the key are moved axially by means of separate levers pivoted to the machine casing and operatively interconnected by means of a connecting rod.