Drill chuck with cushioned tightening sleeve

A drill chuck has a chuck body centered on a longitudinal axis and formed with a plurality of forwardly open angled guides spaced about the axis. Respective jaws displaceable along the guides in the chuck body are each formed with a row of teeth. A tightening sleeve rotatably surrounding the body is axially fixed to a ring rotatable on the body about the axis and formed with a screwthread meshing with the teeth of the jaws so that rotation of the sleeve and ring in one direction moves the jaws radially together and opposite rotation moves them radially apart, A first axially elastically deformable spring seated in the chuck body bears axially forward on the ring, and a second axially elastically deformable spring seated in the chuck body bears axially rearward on the sleeve.

FIELD OF THE INVENTION

The present invention relates to a drill chuck. More particularly this invention concerns a hammer-drill chuck that is tightened and loosened without the use of a chuck key.

BACKGROUND OF THE INVENTION

A drill chuck has as described in U.S. Pat. Nos. 5,145,192 and 5,145,193 a chuck body centered on and adapted to be rotated about a longitudinal axis and unitarily formed with a plurality of forwardly open angled guides angularly spaced about the axis and an axially forwardly directed shoulder. Respective jaws displaceable along the guides in the chuck body are each formed with a row of teeth and a tightening sleeve rotatably surrounds the body and has an axially rearwardly directed shoulder. An inner ring rotatable on the body about the axis is formed internally with a screwthread meshing with the teeth of the jaws so that rotation of the inner ring in one direction moves the jaws radially together and opposite rotation moves them radially apart. This inner ring bears axially forward on the shoulder of the sleeve and axially backward on the shoulder of the body. Interengaging formations rotationally couple the inner ring to the sleeve and a retaining element axially fixed on the chuck body forward of the inner ring bears axially backward on the sleeve. With the system of this prior invention the chuck body has axially rearward of the interengaging formations a predetermined outside diameter and the sleeve has axially rearward of the interengaging formations a predetermined inside diameter greater than the outside diameter of the body. The ring has a predetermined outside diameter smaller than the inside diameter of the sleeve so that the ring can be fitted axially forward into the sleeve and the sleeve and ring together can be fitted axially backward over the body.

While this prior-art chuck is easy to assemble and use, it has the disadvantage that, in particular when hammer-drilling, it vibrates excessively, making tightening and loosening difficult. Furthermore when tightened or loosened by hand it is difficult to control the maximum torque.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide an improved keyless hammer-drill chuck.

Another object is the provision of such an improved keyless hammer-drill chuck which overcomes the above-given disadvantages, that is which is easy to tighten and loosen and where vibration is less of a problem.

SUMMARY OF THE INVENTION

A drill chuck has according to the invention a chuck body centered on and adapted to be rotated about a longitudinal axis and unitarily formed with a plurality of forwardly open angled guides angularly spaced about the axis and with a rim. Respective jaws displaceable along the guides in the chuck body are each formed with a row of teeth. A tightening sleeve rotatably surrounding the body is axially fixed to a ring rotatable on the body about the axis and formed with a screwthread meshing with the teeth of the jaws so that rotation of the sleeve and ring in one direction moves the jaws radially together and opposite rotation moves them radially apart. A first axially elastically deformable spring seated in the chuck body bears axially forward on the ring, and a second axially elastically deformable spring seated in the chuck body bears axially rearward on the sleeve. The rim bears on the chuck body on axial rearward displacement of the sleeve relative to the chuck body.

With such a drill chuck, rotating the tightening sleeve in the tightening direction to move the jaws radially against a tool shank in the chuck will, once the jaws seat on the tool shank, cause the first spring to deform and allow the sleeve to shift axially rearward until its rim bears on the chuck body. From here on in the sleeve is solidly guided and can be rotated to bring considerable torque to bear on the tool. Any vibration will be effectively damped by the springs. Before the jaws actually contact the tool and the sleeve starts to press on the chuck body, the sleeve turns very freely.

According to the invention the sleeve has an axially rearwardly directed shoulder and the ring is pressed axially forwardly thereagainst by the first spring. Thus the axial rearward movement of the sleeve is assisted by the second spring, as is the loosening movement of the sleeve. The second spring is a spring washer bearing at the rear end of the chuck body on a snap ring set in the rear end of the tightening sleeve. This construction makes it very easy to assemble the chuck by slipping the sleeve rearward over the chuck body and snapping the snap ring in once all the parts are in place. Once assembled the tightening ring is guided at its front and rear ends on the chuck body rather than just on the tightening ring as in the prior art.

The body has an axially forwardly directed shoulder bearing on the first spring and the first spring projects radially substantially past the shoulder. More particularly between 25% and 70% of the first spring bears directly on the shoulder. The tightening ring bears backward on the first spring radially outward of the shoulder so the first spring can deform rearward.

Since no substantial pressure is required to damp vibration and guide the tightening sleeve, on tightening of the chuck the sleeves,moves axially backward on the chuck body with elastic deformation of the first spring through a predetermined distance and when the chuck is loose the chuck-body rim is spaced the distance from the chuck body. The sleeve rim is axially forward of the ring and is formed as an inwardly projecting ridge at a front end of the chuck body. Furthermore an elastically deformable body is provided between the rim and the chuck body. This elastically deformable body can be a ring or a lip on the sleeve. This lip is unitarily formed with the sleeve.

The ring according to the invention is formed unitarily of a single piece. As a result it is quite strong and inexpensive to manufacture. It is of reduced diameter since it fits inside the sleeve.

The chuck according to the invention further has a latch mechanism engaged between the sleeve and the body for inhibiting rotation of the sleeve on the body and keeping the chuck tight during a drilling operation. This mechanism includes an intermediate sleeve fixed angularly to the ring, a radially displaceable latch member operable by tightening sleeve and angularly coupled to the intermediate sleeve, and teeth angularly fixed relative to the body and latchingly engageable with the latch member. The teeth can be formed on the first spring or on the chuck body, and can have an axial length longer than the axial travel of the sleeve on the chuck body.

It is also within the scope of the invention to provide a shield cap rotatable on the sleeve at a front end of the chuck body. The sleeve carries a mounting nut formed with an outwardly open groove and the cap has a radially inwardly projecting formation set in the nut so it can rotate, as when the end of the chuck abuts a workpiece.

SPECIFIC DESCRIPTION

As seen in the drawing, a chuck1according to the invention has a machined steel body2centered on an axis6and formed with an axially rearwardly open threaded bore3adapted to receive a spindle of a power unit, an axially forwardly open seat5adapted to receive the shank of a tool, and a passage4connecting the bore3and seat5so that, if desired, a hammer rod can act directly on the rear end of a tool shank in the seat5. Three angled guide passages7equispaced about the axis6open axially forward into the seat5and each hold a respective slidable steel jaw8having an outer edge formed with a screwthread9meshing with an internal screwthread15of a one-piece tightening ring10splined to the inside of a tightening sleeve11coaxially surrounding the chuck body2and extending its full axial length.

A spring steel washer12has an inner periphery bearing axially rearward on an axially forwardly facing shoulder18of the body2and bears axially forward on balls19riding on a rear face of the ring10. The ring10bears axially forward on an axially rearwardly directed shoulder13of the sleeve11so that the sleeve11cannot move axially rearward relative to the ring10and in fact can be considered to be axially locked to the ring10. The shoulder18has a radial dimension equal here to about 25% of the radial dimension of the washer12, although it could in some applications be as much as 70%. Thus the washer12can be deflected backward when pushed by the balls19which engage the washer12radially outward of the shoulder18.

Another spring washer14has its inner periphery bearing axially forward on an axially rearwardly directed shoulder21of the body2and an outer periphery bearing axially rearward on a snap ring17set in an inwardly open groove16at the rear end of the sleeve11. Thus this washer14pulls the sleeve11backward, pressing its shoulder13against the ring10and pressing the ring10via the balls19against the spring washer12set in the body2. The washer14is softer than the washer12so that it presses the balls19against the washer12without significantly deforming it.

In addition the front end of the sleeve11is formed with an inwardly directed rim or ridge20that bears axially rearward via an elastomeric O-ring22on a forwardly directed shoulder of the body2. Thus the sleeve11is limitedly elastically movable axially relative to the body2, braced in both directions by the spring washers12and14. The spacing between the rear face of the rim20and the complementary confronting front face of the body2is equal to the maximum axial displacement of the sleeve11on the body2.

Instead of the O-ring22,FIG. 4shows an arrangement wherein the front rim20is formed with a radially inwardly open groove24forming an elastically deformable lip23bearing axially rearward on the chuck body2. The material of the sleeve11is sufficiently elastically deformable that the lip23can be deformed axially forward to close the groove24without plastic deformation.

While the embodiment ofFIG. 1is a simple chuck, the embodiments ofFIGS. 2 through 5have latching mechanisms25as described in commonly owned U.S. Pat. No. 5,765,839. These mechanisms comprise an intermediate sleeve26fixed on the ring10and holding a latching member27engageable with external teeth28of the washer12. These teeth28could also be formed on the body2in which case they would have an axial length greater than the axial displacement of the sleeve11relative to the body2. The sleeve11is limitedly angularly movable relative to the latching member27so that it can press its end into engagement with the teeth28and thereby form a one-way coupling allowing forward rotation of the sleeve11in a tightening direction while impeding backward rotation as is described in detail in above-cited U.S. Pat. No. 5,765,839.

FIG. 8shows how a shield sleeve29is mounted on the front end of the chuck. It is formed with a radially inwardly projecting groove30fitted in a seat of a nut31carried on the inner end of the body2. The groove30can be formed by embossing after the cap29is mounted on the chuck.