Patent GB-342011-A (GB)
Title: Improvements in chucks as used on lathes, serewing and like machine tools
IPC: B23B31/16
Filed: 1929-11-06
Abstract: 342,011. Chucks. DUDGEON, H. A., 3, St. Andrews Road, Earlsdon, Coventry, and SMALLPEICE, C. D. P., Springhurst, Bubbenhall, near Coventry. Nov. 6, 1929, No. 33704. [Class 83 (iii).] A cam-operated chuck has the jaws or jaw slides operated by eccentric cams or projections on pinions which are rotated on their axes by relative sliding or rotary movement between the part carrying the pinions and a gear wheel or ring with which the pinions engage. The chuck may be arranged to be self-tightening. In one form the jaws e, Figs. 1 and 2, either stepped or shaped to suit particular work, are adjustably secured by screws e<1> to radially movable carriers d provided with cylindrical pins d<1 >located in the eccentric bores of pinions f rotatably mounted in shoes g which are freely movable in an annular recess b<3> in the chuck body b. For actuating the jaws the pinions are rotated in the shoes g by means of a gear ring h which is rotatable on the face-plate a by means of worm teeth h<1> and a worm j. The body b is held in position on the face-plate by a nut c and is rotatable thereon within the limits of a pin l on the body riding in a radial slot a<2> in the face-plate. A circumferential spring normally presses the pin l against one side of the slot a<2> but when the jaws grip the work and the drive is started, the body rotates slightly relatively to the face-plate causing the pinions f to roll on the gear h and cause further tightening of the jaws. The worm, which is held in place by a U-shaped plate k engaging an annular recess j<1>, may be replaced by a helical wheel or the gear ring h may be rotated by hand. In another alternative the gear ring h is secured to the faceplate and a spring rotates the body relatively thereto in the closing direction, opening being performed by restraining rotation of the body b by hand or a brake whilst the face-plate is rotating, or by rotating the body by a tommy-bar whilst the face-plate is stationary. In another form the gear ring h is replaced by an elongated externally toothed ring p, Fig. 10, having helical teeth for engagement with the worm or helical gear j and also with the inner teeth of the pinions q, which are also made helical. In another form the bosses of the pinions f are mounted in cylindrical holes b<5>, Fig. 8, in the body b and the jaw carriers are provided with pins d<1> entering eccentric holes d<2> in the pinions, the holes d<2> being elongated or the pins d<1> made oval as shown. The centres of rotation of the pinions may be on the radial centre lines of the jaws and the pins d<1> offset therefrom as shown, or vice versa. In a further form the pinions q, Fig. 10, are solid and carry eccentric pins or cams q<1> acting on shoes r slidable in transverse slots d<3> in the jaw carriers or alternatively acting on the slots d<3> directly. In another form the worm and wheel or helical gear are dispensed with and the gear t, Fig. 13, is secured to the face-plate a. The body b is then rotated relatively thereto by means of an axially sliding spindle u, splined at u<1> to the lathe mandrel v and provided with quick pitch helical grooves b<9> engaging similar ribs on the interior of the body. The spindle u may be moved axially by means of a piston and an air, water, steam &c. cylinder or by a lever whilst the chuck is stationary or rotating and the helical grooves b<9> and corresponding ribs are a loose fit to allow a self-tightening action as described above. In a further modification the pinions q, Fig. 15, have helical teeth and are rotated by axial sliding movement of a helical gear p splined at u<1> to the mandrel v. The spindle u is moved by pneumatic or hydraulic pressure or a lever, and the body b is loosely attached by screws w and elongated slots v<2> to allow self-tightening. Ball bearings may be provided for the pinions and body to take end thrust due to the spindle u and allow free rotation of the body and pinions.