Patent GB-798248-A (GB)
Title: Improvements in or relating to chucks or mandrels
IPC: B23B31/40
Filed: 1956-09-27
Abstract: 798,248. Chucks; mandrels. WOODWORTH CO., N. A. Sept. 27, 1956 [Oct. 20, 1955], No. 29588/56. Class 83 (3). In a bevel-closing collet-chuck or mandrel, the bevel-operating surfaces on the collet 10 and the operating member or members 18, 20 each consist of an annular series of flat, inclined surfaces 22, 24, 26, 28, which remain flatly in contact with each other over the range of adjustment of the chuck or mandrel. The outwardly-gripping collet 10 of the chuck of Fig. 1 is split at 12, 14 from opposite ends alternately, and its inclined operating faces 22, 24 extending between splits, Fig. 2, are staggered axially. Movement of the member 20 towards the member 18, which is integral with a pneumatic cylinder 34, is effected by springs 64, acting on a piston 40 secured to a rod 54, integral with member 20, and restricted by a tubular extension 60 of the member 18. Movement of the member 20 in the opposite direction, against the influence of the springs 64, is effected manually or, as shown, by compressedair introduced behind the piston, this movement being limited by contact between a flange 46 on the rod 54 and the end of the cylinder, to prevent complete contraction of the collet and thus separation of the bevel surfaces. The collet is ground to size on the chuck, with the flange 46 and the end of the cylinder in engagement. A tool-slot 74 in the end of the member 20 facilitates adjustment, and a sleeve 62 of synthetic-rubber &c. excludes dirt. In a modification, Fig. 3, the collet-operating member 54 is actuated by a draw-bar (not shown), and movement of the member 54 to release the collet is limited by a nut 92. The chuck is mounted on a machine, as by screws engaging slots in the circumference of the base 76, and is lubricated through passages 86, 88. In the construction of Fig. 6, the flat operating- surfaces 110, 112 are formed on the same member 104 and inclined in the same direction, the collet being moved along this member by a draw-bar 114 passing through the member 104 and having a flange 116 bearing against the end of the collet. Instead of two sets of operating surfaces 110, 112, a single set, extending substantially the full length of the collet, may be provided for engaging similar surfaces on the collet, Fig. 7, (not shown). As applied to a pneumatic bevel-closing chuck, Fig. 11, the collect 160 is closed, against the influence of springs 202 acting on the piston 192, by compressed-air fed behind the piston through passages 210, 214, 216. The annular pistonrod 178, sliding over the inner bevel-closing member 172 which is fixed to the chuck-base 186 by screws 173, supports the outer bevelclosing member 170 by a retaining ring 180 and a lock-nut 182. The piston-rod may be a force-fit in the piston, and additionally or alternatively secured, as by screws or screwthreads formed on these parts. Mandrels or collet-chucks. For use as a mandrel mounted between centres 154, 156, Fig. 8, an extension 138 of the operating- member 18 supports the collet 10 and the operating-member 20, which is controlled by a nut 142 and a conical split-nut 144 engaging screw-threads on the extension 138. A tubular extension 140 of the member 20 co-operates with a part 136 of the member 18 to limit expansion of the collet. Work-engaging splines may be formed internally in the case of a bevelclosing collet or externally on the collet, Fig. 15 (not shown).