Drill for smooth- and hex-shank bits

A drill has a drive unit having a spindle rotatable about an axis and having an axially forwardly directed front end formed centered on the axis with an axially forwardly open polygonal-section socket dimensioned to fit with a standard-size bit shank, a chuck body mounted on the spindle, rotatable about the axis at the front end, and having an axially forwardly open tool recess, and a plurality of jaws displaceable in the body to grip a bit in the recess.

FIELD OF THE INVENTION

The present invention relates to a drill. More particularly this invention concerns a drill for use with smooth- and hex-shank bits.

BACKGROUND OF THE INVENTION

The standard power drill, and even a hand drill, has a chuck with a body formed with normally three angled guides holding jaws that can be moved axially forward and radially together to grip a tool on the chuck axis. The rear end of this chuck is fitted to a spindle of a drive unit so that a bit held by the jaws can be rotated. The disadvantage of such an assembly is that, whenever the bit must be changed, the user must laboriously retract the jaws and then advance them again after fitting the new bit to the chuck.

In recent times it has become standard to provide various bits, in particular screw bits, with a standardized 0.25 in (6.35 mm) hex shaft. Such bits are relatively easy to chuck and dechuck from the standard three-jaw chuck, and do not even have to be gripped that tightly as the faceted sides transmit torque very well. Nonetheless it is necessary to operate the chuck, typically by rotating a tightening ring, to chuck and unchuck even such hex-shank bits.

Some tools, particularly screw guns, are equipped with hex-seat sockets. Standard hex-shank bits can be snapped into and out of the socket. Often a retaining ring is pulled axially back to free a bit, but a bit can be chucked simply by being forced back into the socket on the chuck. This system is very convenient, but limits the power unit to use with such hex-shank bits.

It has been suggested to provide a hex-shank socket at the base of the tool recess of a standard three-jaw chuck. Such arrangements have some advantages, but are often clumsy to use and do not transmit torque efficiently between the bit and the drive unit.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide an improved drill for use with smooth- and hex-shank bits.

Another object is the provision of such an improved drill for use with smooth- and hex-shank bits which overcomes the above-given disadvantages.

SUMMARY OF THE INVENTION

A drill has according to the invention a drive unit having a spindle rotatable about an axis and having an axially forwardly directed front end formed centered on the axis with an axially forwardly open polygonal-section socket dimensioned to fit with a standard-size bit shank, a chuck body mounted on the spindle, rotatable about the axis at the front end, and having an axially forwardly open tool recess, and a plurality of jaws displaceable in the body to grip a bit in the recess.

In one system according to the invention the chuck body is provided with an axially rearwardly extending polygonal-section shank complementary to and fitted in the socket. Thus the chuck itself can be easily taken off the spindle, and in its place one can directly install a standard-shank tool bit. The removable chuck can have a chuck body formed with an annular collar centered on the axis and closely complementarily surrounding or fitting inside the front spindle end. Such a collar ensures perfect on-center rotation of the chuck.

In another system according to the invention the spindle end is externally threaded and the chuck body has a rearwardly open threaded bore complementarily fitted to the spindle end. The chuck body is formed between the recess and the bore with an axially throughgoing passage of a diameter sufficient to pass the bit shank. Thus a standard-shank bit can simply be poked right down through the chuck and seated directly in the spindle, so that no torque is actually transmitted by the chuck to the bit.

In accordance with the invention the bit shank is formed with a radially outwardly open groove. The retaining element is urged radially inward into the groove of the shank in the socket so that the retaining element holds the shank in the socket. Thus the bit is releasably held in the chuck. With this system either the retaining element is radially displaceable in the chuck body or in the spindle. The biasing means is a spring and the retaining element is a ball.

Alternately a retainer is engageable with the retaining element and displaceable between an unactuated position pressing the retaining element into the groove and an actuated position allowing the retaining element to move out of the groove. Another spring urges the retainer into the unactuated position. Normally the retainer is annular and centered on the axis and is movable axially between the actuated and unactuated positions. It can be radially displaceable in the chuck body or in the spindle.

According to another feature of the invention the spindle includes an ejector body forming the socket and axially displaceable between an axially outer position and an axially inner position. A spring or the like urges the ejector body into the outer position. Another retaining element is radially displaceable between a radially inner position blocking axial outward movement of the ejector body and a radially outer position permitting such movement and another retainer engaging the retaining element is movable between an unactuated position holding the retaining element in the inner position and an actuated position allowing the retaining element to move into the outer position. Another urges the retainer into the unactuated position. Thus this ejector can be released to push a bit out of the socket to make it easy to remove from the chuck. This second retainer is an axially displaceable sleeve having a cam formation engageable with the retaining element. It can in fact be the same sleeve that works with the retaining element that holds the tool in the socket.

The spindle according to the invention can include a main part having an externally threaded end and a sleeve having an internally threaded rear portion fitting with the main-part end and a front portion forming the socket. This constitutes an adapter allowing the instant invention to be retrofitted to an existing drill.

One of the jaws according to the invention is formed with a transversely open recess. An element radially movable in the chuck body is engageable in this recess, and a spring urges this element toward the one jaw. The recess and jaw are so positioned that the element can only engage in the recess when the jaw is retracted enough to allow a bit shank to pass the jaws and engage in the socket. This gives the user tactile or audible feedback so as to know, when backing off the jaws to fit a standard-shank bit into the socket, when they are spread enough to let the standard-shank bit pass.

SPECIFIC DESCRIPTION

As seen inFIGS. 1 and 6a chuck1is carried on a spindle3of a drive or power unit2. The chuck1has a body5centered on an axis6of the spindle3and is formed with three angularly equispaced and angled guide passages7holding respective jaws8having inner edges9that project into an axially forwardly open tool recess10at a front end of the chuck body5. A tightening sleeve11is rotatable about but axially fixed relative to the axis6on the body5and carries a ring12whose inner surface is formed with a screwthread meshing with teeth13on outer edges of the jaws8. Thus rotation of the sleeve11and ring12in one direction will bring the jaws8axially forward (downward inFIG. 1) and radially together and opposite rotation will move them axially backward (upward inFIG. 1) and radially apart. The rear end of the chuck body5is formed centered on the axis6with a rearwardly open threaded bore16into which the spindle3is threaded. This is all standard.

According to the invention the axial front end of the spindle3is formed centered on the axis6with an axially forwardly open hex socket or seat14of standard quarter-inch size. A hex shank15, which here is part of a standard bit23, fits complementarily in this socket14and extends axially forward out through a cylindrical passage17forming a rearward extension of the tool recess10that opens into the bore16the spindle3is fitted to. The shank15is formed with a radially outwardly open groove44in which engages a spring-loaded ball18movable radially in a cylindrical passage19formed in the body5.

As shown inFIG. 6, a spring-biased ball37can engage transversely in a transversely outwardly open groove36formed in one of the jaws8. This engagement only takes place when the jaws8have been retracted enough to afford clearance for a quarter-inch shank15to pass backward in the recess10past these jaws8. Thus as the user backs off the jaws8, a click will be emitted when the ball37fits into the groove36, thereby giving an audible indication that the chuck1is opened enough to allow a quarter-inch hex bit to be fitted to the seat14.

InFIG. 2the ball18is not spring loaded but instead is normally held in place by a pin22that in turn is normally pressed against the ball18by a spring-loaded retainer20whose outer button end21can be pushed radially inward to allow the pin22to retract. Thus when the button21is pushed, the ball18can retract and free the shank15. The button21must therefore be depressed to free the bit23.

The system ofFIG. 3has an axially displaceable plastic retaining sleeve27urged axially backward by a spring26and having a metallic liner28that serves to press the ball18radially inward in the normal axial rearward position of the sleeve27. Axial forward displacement of this sleeve27allows the ball18to move radially outward and release the shank15. In addition here the spindle3is provided with an axially displaceable ejector body32having a rear end fitting complementarily in the seat14and urged axially forward therefrom by a spring42and a front end forming a seat43identical to the seat14and itself holding the shank15. Another retaining ball33like the ball18normally bears radially inward on the ejector32and prevents it from moving axially forward.

When the sleeve27is retracted axially backward (up in FIG.3), the balls18and33can move radially outward, freeing the bit23and the ejector32so that both will move axially forward. This action frees the tool23to move axially forward, and frees the ejector32to also move axially forward under the force of its spring42and eject this tool23.

FIG. 4shows a system substantially identical toFIG. 3, except that no second retainer ball33is provided.

InFIG. 5the retaining sleeve27bears axially forward on the pin22so that, when it is retracted, the ball18is free to retract and release the bit23. Here the ejector32is formed by a spring fitted in the spindle3and bearing directly on the rear end of the bit23.

FIG. 7shows an adapter24having a rearwardly open threaded seat25that fits complementarily with and in fact effectively forms part of a standard threaded drill spindle3. Thus this adapter24is intended to be permanently mounted on a standard threaded drill spindle3and itself forms the seat14and carries the retainer ball18and sleeve27. This adapter24is employed to retrofit a drive unit with a standard threaded spindle3to comply with the invention.

The chucks of FIG.8and ofFIGS. 9 through 11have a quarter-inch hex shank15′ formed on or fixed to the chuck body5so that the entire chuck1can be released by pushing forward the retaining sleeve27.

FIG. 12shows a chuck where the retaining sleeve27is pushed backward, not forward as inFIG. 3, to free the shank15. To this end a radially displaceable button29urged radially outward by the spring26has an angled cam face30engaging a complementary face31of the sleeve27so that, when the button29is pressed inward, the sleeve27moves back and releases the ball18. The button29is provided in a housing4of the drive unit2so that it does not rotate while, of course, the sleeve27rotates with the chuck body5.

Here the chuck body5has a collar formation34of cylindrical shape centered on the axis6and fittable in a complementary front end35of the spindle3to center the chuck body5, which is unitarily formed with the shank15, on the spindle6. The arrangement ofFIG. 13is similar but the shank15is a separate part fixed in the chuck body5.

InFIG. 14the retaining sleeve27acts on both the ball33that holds back the ejector32and the ball18that retains the shank15, which here is part of the chuck body5, on the adapter24. Forward shifting of the sleeve27against the force of its spring26will therefore free the chuck1and also allow the adapter32to push the tool23forward off the adapter24. In this embodiment the centering collar34on the chuck body5engages radially around the front end35of the adapter24, inFIG. 15the structure is similar but the centering collar34engages inside it.

The system ofFIGS. 16 and 17has a pair of diametrally opposite buttons29that are depressed to release and eject the chuck1from the spindle3. Here the buttons29are also provided in the body4of the drive unit2so that they do not rotate with the spindle3.

The housing4of the system ofFIGS. 18 and 19and ofFIGS. 20 and 21has a ring41that can be rotated to cam down the retaining sleeve27by an appropriate screwthread connection. Thus the user rotates the ring41to release the chuck1.

FIG. 22shows an arrangement where a rotary drive coupled by an unillustrated clutch of a motor of the drive unit2serves to axially displace a rod39that can push the retaining sleeve27. InFIG. 23a solenoid40acting on a pusher body38fulfills the same function.