Expansible mandrel

1,015,198. Mandrels. ERICKSON TOOL CO. Oct. 30, 1962, No. 41055/62. Heading B3B. An expansible mandrel comprises two sets of work-gripping jaws, one set 28 of which is axially adjustable, means for expanding one set of jaws 25 and means 20 for transmitting the force to expand the other set of jaws. In operation, a workpiece is placed over the mandrel and spring-pressed plungers 38 serve to centre it. A head 14 is then moved axially by a drawbar 13 causing the collet jaws 52 to be moved axially by a draw-bar 13 causing the collet jaws 25 to be moved axially and expanded by a conical ring 24. The conical ring 24 also moves axially thus moving keys 20 engaging a sleeve 30. The sleeve 30 has a flange to engage a conical ring 29 which thus expands the other collet jaws 28. When a different length of workpiece is to be gripped, the sleeve 30 and a sleeve 32 associated therewith are rotated to disengage threads on the sleeve 30 and the keys 20 and to move the threaded portions of the sleeve opposite flats 19 on the mandrel body 18. The sleeve 30 is then adjusted axially carrying with it the collet jaws 28. The mandrel is mounted on a spindle by a flange 11. In a modification, movement of a head 44, Fig. 5, moves keys 47A to expand a collet 48. A ring 51 is consequently moved and through further keys actuates a second collet 55.