Patent GB-329342-A (GB)
Title: Screw-cutting die heads
IPC: B23G5/12
Filed: 1929-02-14
Abstract: 329,342. Marks, Sir G. C., (Landis Machine Co.). Feb. 14, 1929. Screwing die-heads.-In a screw-cutting diehead of the kind comprising a front unit carrying tangential chasers and a rear unit carrying driving and locking means, the front unit may float relatively to the rear unit to allow for mis-alignment of the work and the driving and locking means are independent of each other. The die-head comprises a front unit having a body 20, Fig. 4, supporting a rotary ring 21 for operating the pivoted die carriers and a rotary adjusting ring 22, the rings being operated by a worm and spring as described in Specifications 228,209, 274,924 and 275,282, and being confined between collars 23, 24 on the body 20. The body 30 of the rear unit has collars 37, 37' between which is secured a ring 32 carrying locking pins 34 having blunt ends engaging hardened bushes 27<1> in the opening ring 21 so as to lock the ring in the cutting position. The closing pins 35 are secured to a ring 33 sliding on the body 30 and have conical ends 36 for engagement with hardened bushes 27 in the ring 21 to rotate this ring to the closing position. Axially arranged springs are contained in pockets in the rings 32, 33, so as normally to force these rings apart. The front and rear bodies 20, 30 are normally kept in contact by spring 40 surrounding headed pins 39 screwed into the body 20 and passing into apertures in the body 30. To allow the front unit to float relatively to the rear unit, clearance is provided at 41, 42, 43, 44 and 44<1>, Fig. 12, and in order to relieve the locking pins from the cutting torque, the front unit is driven by pins 52 seated in co-axial bores in the two bodies. In operation, the ring 33 is acted upon by a roller &c. to cause the closing pins 35 to advance, first moving the front unit until the heads 39<1> of the pins 39 engage shoulders 39<b> on the rear unit and so prevent further movement and then rotating the ring 21 to the closed position in which it is locked by the pins 34. The springs then withdraw the ring 33 but leave the ring 21 locked as shown in Fig. 4. In a modified construction the front unit 10', Fig. 17, carries the rotatable operating and adjusting rings 11', 12' respectively and the rear unit 36<1> carries a slidable ring 28<1> having the conically ended closing and locking pins 29<1> thereon. The drive from the rear to the front units is effected through pins 20', Fig. 24, and clearances are provided at 32', 33<1>, 34<1>, 35<1> and 35<a> to permit the front unit to float. Rearward movement of the ring 28<1> is limited by headed pins 31 and the two units are held in contact with each other by springs 17', Fig. 19, surrounding headed pins 38<1> which are attached to the rear unit by removable pins 40'. In operation the head is advanced in the closed position, as shown in Fig. 17, on to the work, and when the desired length of thread has been cut further movement of the rear unit 36' is stopped whereupon the front unit is drawn away from the rear unit and the pins 29' release the ring 11' and allow it to be rotated by its spring to open the die-head. The springs 41<1> then return the front and rear units into contact and the dies may be re-set by pushing the ring 28<1> forwards.