Lockable drill chuck

Abstract

A drill chuck has a chuck body centered on and rotatable about an axis and formed with angled guides and respective jaws slidable in the guides axially forward and radially toward each other and axially rearward and radially away from each other. An annular tightening element is limitedly axially shiftable on the sleeve between a front position and a rear position. Screwthreads engaged between the element and the jaws axially displace the jaws forward on rotation of the element in a tightening direction and axially displace the jaws rearward on rotation of the element in an opposite loosening direction. Respective annular arrays of teeth angularly fixed on the element and the body are interengaged and prevent relative rotation of the element and body in the rear position of the element and are spaced and permit relative rotation of the element and body in the front position of the element.

Description

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become more readily apparent from the following description, lo it being understood that any feature described with reference to one embodiment of the invention can be used where possible with any other embodiment and that reference numerals or letters not specifically mentioned with reference to one figure but identical to those of another refer to structure that is functionally if not structurally identical. In the accompanying drawing:

FIG. 1 is a side view of a drill chuck according to the invention, with the left half illustrated in longitudinal section;

FIG. 2 is a longitudinal section through the insulated grip sleeve;

FIG. 3 is a side view of an insulated tightening sleeve;

FIG. 4 a is a section taken along line IV-IV of FIG. 1 with the locking teeth engaged;

FIG. 4 b is the same section in a position with play between the locking teeth for allowing relative rotation of the grip sleeve and the tightening sleeve;

FIG. 4 c is the same section with the locking teeth of the tightening sleeve between the locking seats of the grip sleeve;

FIGS. 5, 6, and 7 are views like FIG. 1 of variations on the drill chuck according to the invention.

SPECIFIC DESCRIPTION

As seen in FIG. 1 a drill chuck 1 has a chuck body 2 that on the axially rearward end has a threaded hole 3 for a spindle of a drill, not illustrated in the drawing. In addition, clamping jaws 6 are longitudinally slidable in guides 5 running at a small acute angle to a chuck axis 4, and open into a tool seat 7 provided at the axial front end of the chuck body 2. The clamping jaws 6 each have a radially outwardly projecting row of teeth 8 engaging in an annular screwthread 9 of a threaded tightening ring 11 that is angularly and axially fixed on a tightening sleeve 10 rotatable and limitedly axially shiftable on the chuck body 2. Also fixed both axially and angularly on the chuck body 2 is a grip sleeve 12 (FIGS. 1-5) or an annular disk 17 (FIGS. 6 and 7), that may also be molded in one piece with the chuck body 2. The sleeve 12 has a flat rear flange 18 fixed to the body 2 and rearwardly closing the guide passages 5. Either the disk 17 or the flange 18 is formed with axially throughgoing holes 19 through which drilling dust can exit. In addition FIG. 7 shows how the holes 19 are enlarged so that the jaws 6 can pass through them and are not blocked in their rearward travel.

According to the invention the tightening sleeve 10 is formed at its axial rear end, which is of frustoconical shape, with an annular array of generally radially outwardly directed but angled teeth 13′ and the grip sleeve 12 is formed inside its axial front end, which is of complementary frustoconical shape, with a complementary annular array of generally radially inwardly directed teeth 13″ fittable with the teeth 13′. The teeth 13′ and 13″ are dimensioned relative to the limited axial travel of the sleeve 10 on the body 2 such that they can be engaged or disengaged. More particularly when the sleeve 10 is pushed forward, the teeth 13′ and 13″ are largely disengaged, at most touching as they angularly pass each other to make a ratcheting sound. When the sleeve 10 is pushed back, which invariably happens when the jaws 6 are bearing on a tool, the teeth 13′ and 13″ engage solidly in each other and prevent any axial rotation of the sleeve 10 (and with it the ring 11) so that the chuck 1 cannot loosen. The action is natural and intuitive: the user naturally pushes the sleeve 10 axially forward when gripping and turning it, and the rearward force of drilling naturally pushes the sleeve 10 back to lock it.

This axial displacement of the tightening sleeve 10 is facilitated by the fact that the threaded ring 11 is axially rearwardly braced on the chuck body 2 by an elastically deformable washer or pressure ring 14. The threaded ring 11 itself is designed as a one-piece threaded ring 11, and is axially forwardly braced against a shoulder of the tightening sleeve 10 that is in turn braced axially forward on the chuck body 2 a snap ring 15 shown in FIG. 1.

Whereas in FIGS. 1-3 the arrays of locking teeth 13′ and 13″ are frustoconical with the teeth 13′ inside the teeth 13″, in FIG. 5 the locking teeth 13′ and 13″ of the grip sleeve and the tightening sleeve 10 are oppositely oriented, that is with the teeth 13′ facing outward and the teeth 13″ facing inward.

The embodiment of FIG. 1 has internal surfaces 16 on the tightening sleeve 10 for guiding drilling dust so that it does not get between the locking teeth 131 and 13″, since this drilling dust could damage the play between the locking teeth 13′ and 13″.

According to one illustrated embodiment not illustrated in the drawings, it is of course possible for the locking teeth 13″1 of the grip sleeve 12 and/or the teeth 13′ of the tightening sleeve 10 to be provided on a ring having increased wear resistance, in particular made of metal, which is angularly fixed to the grip sleeve 12 or the tightening sleeve 10, which itself may be made of plastic.

For tightening a drill chuck 1, the starting point is the opened state of the drill chuck, in which play is provided between the locking teeth 13′ and 13″. When a drill bit is chucked, the clamping jaws 6 make contact with it and are axially rearwardly pressed against the threaded ring 11, causing the pressure ring 14 to elastically deform. This allows the threaded ring 11 together with the tightening sleeve 10 to move axially rearward. The locking teeth 13′ and 13″ engage and lock the angular position of the tightening sleeve 10 with respect to the chuck body 2. When the teeth 13′ and 13″ fit together (FIG. 4d), the tightening sleeve 10 is locked on the body 2.

Claims

1. A drill chuck comprising: a chuck body centered on and rotatable about an axis and formed spaced angularly around the axis with a plurality of angled guides;respective jaws slidable in the guides axially forward and radially toward each other and axially rearward and radially away from each other;an annular tightening element limitedly axially shiftable on the sleeve between a front position and a rear position;screwthread formations engaged between the element and the jaws for axially displacing the jaws forward on rotation of the element in a tightening direction and for axially displacing the jaws rearward on rotation of the element in a loosening direction; andrespective annular arrays of teeth angularly fixed on the element and the body, the arrays being interengaged and preventing relative rotation of the element and body in the rear position of the element and being spaced and permitting relative rotation of the element and body in the front position of the element.

2. The drill chuck defined in claim 1, further comprising an elastic biasing ring engaged between the element and the body and urging the element axially forward into the front position.

3. The drill chuck defined in claim 1 wherein the element includes a ring formed with the respective array of teeth and a sleeve surrounding and fixed to the ring.

4. The drill chuck defined in claim 3 wherein the ring is one piece

5. The drill chuck defined in claim 1 wherein the body and element have generally complementary substantially frustoconical surfaces confronting each other and carrying the respective arrays of teeth.

6. The drill chuck defined in claim 4 wherein the element has an axial rear end formed with the respective frustoconical surface and array of teeth.

7. The drill chuck defined in claim 1 wherein the chuck body includes at a rear end a radial projection.

8. The drill chuck defined in claim 7 wherein the radial projection is formed as a plate and has an outer edge formed with the respective surface and teeth.

9. The drill chuck defined in claim 7 wherein the chuck body further includes a grip sleeve projecting axially forward from an outer edge of the projection and itself formed with the respective surface and teeth.

10. The drill chuck defined in claim 9 wherein the grip sleeve has an axial front end formed with the respective surface and grip teeth.

11. The drill chuck defined in claim 1 wherein the chuck body or the tightening element is provided with a hardened ring forming the respective surface and teeth.

12. The drill chuck defined in claim 11 wherein the hardened ring is metal.

13. The drill chuck defined in claim 1 wherein the chuck body or the tightening element are of metal.