| 摘要 |
1,211,899. Screwing die heads. GEORG. FISCHER A.G. 28 June, 1968 [30 June, 1967], No. 31133/68. Heading B3N. A die head for cutting a taper screw thread on the end of a pipe 1 comprises a rotatable body 15 carrying radially-disposed die members 24, a sleeve 2 having an external screw thread 12 of the same pitch as that to be formed on the pipe engaged with an internal screw thread 13a in a lead nut 13 secured to the body 15, a slipclutch 52 for disengageably coupling the sleeve 2 and body 15 for conjoint rotation, and a mandrel 4a, 4b which is axially displaceable in the sleeve 2 by means of interengaging screw threads 5, 50 and has an end which projects from the sleeve for insertion in the pipe 1 and is formed with inclined grooves 7 for radially displacing three wedges 8 located around the mandrel end into clamping engagement with the interior of the pipe 1 to secure the die head thereto. A die adjusting sleeve 20 rotatable with the body 15 has an inclined nose 27 engaging grooves 26 in the die member 24 and is in screw-threaded engagement with a thread 19 of greater pitch than the threads 5, 50 on a ring 17 which is connected to the sleeve 2 by a spigot screw 16 engaging a slot 40 so as not to rotaterelative to the sleeve but to be capable of limited axial movement resisted by a brake spring 36. The slip-clutch 52 couples a clutch ring 54 which is positively driven through a ratchet 51 when the body 15 is rotated in the thread-cutting direction to a coupling sleeve 55 which is adjustably secured to the sleeve 2 by a claw ring 53 and a nut 57 permitting adjustment of the thread diameter. In operation, the pipe 1 or the mandrel 4a, 4b is held fast and either the mandrel inserted in the pipe or the pipe fitted over the mandrel, and the body 1 is rotated manually by a hand crank or ratchet or is motor-driven through reversing gear engaged with a claw ring 56 on the body. Initial rotation of the body 15 is transmitted through the slipclutch 52 to rotate the sleeve 2 on the mandrel and tighten the wedges 8, but when the clamping torque attains a set value the clutch 52 slips and after one revolution of the body on the sleeve the ratchet 51 disengages from the clutch ring 54. The body 15 then advances along the sleeve 2, the die adjusting sleeve 20 being advanced more rapidly than the body by the thread 19 so that the die members 24 are progressively moved outwards to form the tapered thread. When the thread is complete the lead nut 13 abuts the end of the ring 17 which is axially displaced together with the die adjusting ring 20 to disengage the die members 24 from the thread. |
