Locking chuck

A chuck for use with a driver having a drive shaft includes a cylindrical body having a nose section and a tail section. The tail section is configured to receive the drive shaft and the nose section includes an axial bore. A plurality of jaws is movably disposed with respect to the body in communication with the axial bore. A sleeve is rotatably mounted about the body in operative communication with the jaws. A first ring is adjacent the sleeve, a second ring is adjacent the body, and one of the first ring and the second ring defines a ratchet and the other defines a pawl biased away from the ratchet. The ratchet and the first pawl are configured so that when the first pawl engages the ratchet, the ratchet and first pawl prevent the first ring from rotating in an opening direction with respect to the second ring.

FIELD OF THE INVENTION

The present invention relates generally to chucks for use with drills or with electric or pneumatic power drivers. More particularly, the present invention relates to a chuck of the keyless type which may be tightened or loosened by hand or actuation of the driver motor.

BACKGROUND OF THE INVENTION

Both hand and electric or pneumatic tool drivers are well known. Although twist drills are the most common tools on such drivers, the tools may also comprise screw drivers, nut drivers, burrs, mounted grinding stones, and other cutting or abrading tools. Since the tool shanks may be of varying diameter or of polygonal cross section, the device is usually provided with a chuck adjustable over a relatively wide range. The chuck may be attached to the driver by a threaded or tapered bore.

A variety of chucks have been developed in the art. In an oblique jawed chuck, a chuck body includes three passageways disposed approximately 120° apart from each other. The passageways are configured so that their center lines meet at a point along the chuck axis forward of the chuck. The passageways constrain three jaws which are moveable in the passageways to grip a cylindrical or polygonal tool shank displaced approximately along the chuck center axis. The chuck includes a nut that rotates about the chuck center and that engages threads on the jaws so that rotation of the nut moves the jaws in either direction within the passageways. The body is attached to the drive shaft of a driver and is configured so that rotation of the body in one direction with respect to the nut forces the jaws into gripping relationship with the tool shank, while rotation in the opposite direction releases the gripping relationship. The chuck may be keyless if it is rotated by hand. Various configurations of keyless chucks are known in the art and are desirable for a variety of applications.

SUMMARY OF THE INVENTION

The present invention recognizes and addresses the foregoing considerations, and others, of prior art constructions and methods. One embodiment of the present invention includes a chuck for releasably attaching a tool with a shank to a manual or powered driver having a rotatable drive shaft. The chuck includes a generally cylindrical body having a nose section and a tail section, the tail section is configured to receive the drive shaft and the nose section has an axial bore formed therein. A plurality of jaws is movably disposed with respect to the body in communication with the axial bore. A sleeve is rotatably mounted about the body in operative communication with the jaws so that rotation of the sleeve in a closing direction moves the jaws toward the axis of the axial bore and rotation of the sleeve in an opening direction moves the jaws away from the axis. A first ring is adjacent the sleeve, a second ring is adjacent the body, and one of the first ring and the second ring defines a ratchet and the other of the first ring and the second ring defines a pawl biased away from the ratchet. The ratchet and the first pawl are configured so that when the first pawl engages the ratchet, the ratchet and first pawl prevent the first ring from rotating in the opening direction with respect to the second ring.

Another embodiment includes a chuck for releasably attaching a tool with a shank to a manual or powered driver having a rotatable drive shaft. The chuck includes a generally cylindrical body having a nose section and a tail section, the tail section is configured to rotate with the drive shaft and the nose section has an axial bore formed therein and a plurality of passageways formed therethrough and intersecting the axial bore. A plurality of jaws is movably disposed in the passageways and a generally cylindrical sleeve is rotatably mounted about the body. A nut is rotatably mounted about the body and in operative communication with the jaws so that rotation of the nut in a closing direction moves the jaws toward the axis of the axial bore and rotation of the nut in an opening direction moves the jaws away from the axis. A first ring is adjacent the nut, a second ring is adjacent the body, and the second ring defines a ratchet and the first ring defines a deflectable first pawl biased away from the ratchet. The ratchet and the first pawl are configured so that when the first pawl engages the ratchet, the ratchet and first pawl permit the first ring to rotate in the closing direction with respect to the second ring but prevent the first ring from rotating in the opening direction with respect to the second ring. The sleeve is in operative communication with the nut so that the sleeve rotationally drives the nut but is rotatable with respect to the nut between a first rotational position and a second rotational position. The sleeve defines a cam surface disposed with respect to the first pawl so that the cam surface engages the first pawl with the ratchet when the sleeve is in the second position with respect to the nut and releases the first pawl to disengage the ratchet when the sleeve is in the first position with respect to the nut.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring toFIGS. 1 and 2, a chuck10includes a body14, a nut16, a front sleeve18, a nose piece20and a plurality of jaws22. Body14is generally cylindrical in shape and comprises a nose or forward section24and a tail or rearward section26. Nose section24has a front face28transverse to the longitudinal center axis30of body14and a tapered surface32at its forward end. The nose section defines an axial bore34that is dimensioned somewhat larger than the largest tool shank that the tool is designed to accommodate. A threaded bore36is formed in tail section26and is of a standard size to mate with the drive shaft of a powered or hand driver (not shown). The bores34,36may communicate at a central region38of body14. While a threaded bore36is illustrated, such bore could be replaced with a tapered bore of a standard size to mate with a tapered drive shaft. Furthermore, body14may be formed integrally with the drive shaft.

Body14defines three passageways40to accommodate three jaws22. Each jaw is separated from the adjacent jaw by an arc of approximately 120°. The axes of passageways40and jaws22are angled with respect to the chuck center axis30such that each passageway axis travels through axial bore34and intersects axis30at a common point ahead of the chuck body. The jaws form a grip that moves radially toward and away from the chuck axis to grip a tool, and each jaw22has a tool engaging face42generally parallel to the axis of chuck body14. Threads44, formed on the opposite or outer surface of each jaw22, may be constructed in any suitable type and pitch.

As illustrated inFIGS. 1 and 2, body14includes a thrust ring46that, in a preferred embodiment, may be integral with the body. It should be understood, however, that thrust ring46and body14may be separate components. Thrust ring46includes a plurality of jaw guideways48formed around its circumference to permit retraction of jaws22therethrough and also includes a ledge portion50to receive a bearing assembly as described below.

Body tail section26includes a knurled surface54that receives an optional rear sleeve12in a press fit. Rear sleeve12could also be retained by press fit without knurling, by use of a key or by crimping, staking, riveting, threading or any other suitable securing mechanism. Further, the chuck may be constructed with a single sleeve having no rear sleeve.

Nose piece20retains nut16against forward axial movement. The nose piece is press fit to body nose section24. It should be understood, however, that other methods of axially securing the nut on the body may be used. For example, the nut may be a two-piece nut held on the body within a circumferential groove on the outer circumference of the body. Nose piece20may be coated with a non-ferrous metallic coating to prevent rust and to enhance its appearance. Examples of suitable coatings include zinc or nickel, although it should be appreciated that any suitable coating could be utilized.

Front sleeve18includes outer sleeve18aand inner sleeve18b. The outer circumferential surface of outer sleeve18a may be knurled or may be provided with longitudinal ribs77or other protrusions to enable the operator to grip it securely. In like manner, the circumferential surface of rear sleeve12, if employed, may be knurled or ribbed as at83if desired.

Front sleeve18is secured from movement in the forward axial direction by an annular shoulder90on nose piece20. A frustoconical inner section95at the rearward end of the nose piece facilitates movement of jaws22within the chuck.

Inner sleeve18bof front sleeve18and rear sleeve12may be molded or otherwise fabricated from a structural plastic such as polycarbonate, a filled polypropylene, for example a glass filled polypropylene, or a blend of structural plastic materials. Other composite materials such as, for example, graphite filled polymerics may also be suitable in certain environments. As should be appreciated by one skilled in the art, the materials for which the chuck of the present disclosure is fabricated will depend on the end use of the chuck, and the above materials are provided by way of example only. Inner sleeve18bis received within outer sleeve18ain a press-fit. Inner sleeve18balso includes a plurality of equally spaced grooves21, each of which receives an inwardly depending tab19of outer sleeve18a. The width of each groove21is the same as that of each tab19so that the bond between inner and outer sleeves18aand18bis enhanced.

Nut16has threads56for mating with jaw threads44. Nut16is positioned about the body in engagement with the jaw threads so that when the nut is rotated with respect to body14, the jaws will be advanced or retracted depending on the rotational direction of nut16.

As illustrated inFIG. 3, the forward axial face of nut16includes recesses62that receive respective drive dogs64(FIG. 1) extending from the inner surface of inner sleeve18b. The angular width of the drive dogs is less than that of the recesses, resulting in a slight range of relative rotational movement, for example between 6° and 10°, between the nut and the front sleeve.

Nut16also defines a plurality of grooves formed as flats68about the outer circumference of the nut. Flats68receive respective tabs70extending forward from a first ring72. The engagement of tabs70and flats68rotationally fix the first ring to the nut, although it should be understood that there may be a slight rotational tolerance between the two. The operation of the first ring is discussed in greater detail hereafter.

A bearing assembly is disposed between nut16and the chuck body. Nut16rests on an inner race71of the bearing assembly. Inner race71receives a plurality of bearing elements, in this case bearing balls,76disposed between it and a second ring78(or outer race of the bearing assembly) supported to the rear by thrust ring ledge50(FIG. 2). Outer race78freely rotates about body14until it becomes frictionally fixed by rearward force during the loading of tools into the chuck, as discussed in greater detail hereafter.

Outer race78also includes a ratchet in the form of an annular ratchet ring79which is press fit onto outer race78. In the illustrated embodiment, the ratchet is formed by a plurality of sawtooth-shaped teeth84disposed about an outer circumferential surface of the ratchet ring. A first pawl86extends from one side of each tab70and is biased radially outward from the first ring, thereby urging a distal end88of each first pawl86away from the annular array of teeth84on the ratchet ring.

Referring now toFIG. 4, each tooth84has a first side with a slope approaching 90°. The second side has a lesser slope. First pawl86is deflectable and is generally disposed in alignment with the slope of the second side. Thus, rotation of first ring72in a direction90(closing direction) with respect to outer race78, once outer race78has become non-rotatably fixed to the chuck body by rearward force, moves distal ends88repeatedly over teeth84, causing a clicking sound as they fall against each subsequent second side of each tooth84. This configuration of teeth84and first pawls86, however, prevents the rotation of first ring72in an opposite direction92(opening direction) once outer race78has become non-rotatably fixed to the chuck body. Application of rotational force to the inner race in this direction forces distal ends88into the steep-sloped first sides of teeth84. Since distal ends88of first pawls86are generally perpendicular to the first sides, the first pawls86do not deflect to permit rotation.

As discussed below, direction90corresponds to the closing direction of the chuck, while direction92corresponds to the opening direction of the chuck. Accordingly, when first pawls86engage ratchet teeth84, the teeth permit movement of first ring72in the closing direction of the chuck but prevent movement of first ring72in the opening direction.

A third ring91is disposed between the bearing assembly and thrust ring46of the chuck body. A second pawl94extends circumferentially about third ring91and selectively engages inner sleeve18b. Third ring91is freely rotatable about the chuck body until sufficient rearward force is exerted thereon such that third ring91becomes frictionally fixed to the thrust ring, as discussed in greater detail hereafter.

First and second pawls86and94include biasing tabs96and98at their distal ends. An inner circumferential surface of inner sleeve18bdefines a plurality of equally spaced recesses100. During operation of drill chuck10, each biasing tab98is received in one of these recesses. Inner sleeve18balso defines a second recess104and a cam surface106. Depending on the rotational position of front sleeve18with respect to first ring72and nut16, each biasing tab96is received either by cam surface106or by second recess104. The inner sleeve includes a second recess104and cam surface106for each tab96.

FIG. 6Billustrates the disposition of first pawls86and second pawls94when front sleeve18is in a first of two positions with respect to nut16, whileFIG. 6Cillustrates these components when the front sleeve is in a second position with respect to the nut. For ease of illustration, both figures omit the nut. However, referring toFIGS. 3 and 6C, each drive dog64is disposed against or adjacent to a side108of the gap62in which is it received when sleeve18is in the second position with respect to the nut. Each biasing tab98of each second pawl94is received in a recess100a, and each biasing tab96of each first pawl86is positioned on a respective cam surface106. Accordingly, distal end88of each first pawl86is forced inwardly and engages ratchet teeth84, and first ring72can rotate only in direction90with respect to outer race78.

Referring now toFIGS. 5 and 6B, when sleeve18moves in opening direction92with respect to the outer race, each biasing tab98moves out of the initial recess100aand into an adjacent recess100b, as indicated by arrow108. Each biasing tab96rides off of respective cam surface106and into recess104, as indicated by arrow110. This allows each deflectable first pawl86to return to its normal, outwardly biased position, thereby disengaging distal ends88of first pawls86from ratchet teeth84. Thus, first ring72is free to rotate with respect to chuck body12. Continued rotation of sleeve18in opening direction92eventually causes the rotation of nut16in the opening direction, thereby releasing the rearward axial force exerted on outer race78. As such, outer race78is also free to rotate with respect to chuck body12since rearward axial force no longer frictionally locks outer race78to the chuck body.

As described in more detail below, when front sleeve18rotates in direction92so that the first and third rings move from the positions shown inFIG. 6Cto the position shown inFIG. 6B, drive dogs64move within grooves62of nut16(FIG. 1) SO that each drive dog is against or immediately adjacent to a side110of the groove.

In operation, and referring toFIGS. 1,4,6B and6C, nut grooves62receive drive dogs64when the chuck is between fully opened and fully closed positions so that the drive dogs are adjacent groove sides110. First ring72is disposed with respect to outer race78so that biasing tabs96are received by respective second recesses104. That is, front sleeve18is in the first position with respect to the nut. As in both the first and second positions, biasing tabs98are received in respective recesses100. In this condition, biasing tabs96and second recesses104rotationally fix first ring72to front sleeve18. Since first ring72is rotationally fixed to nut16by tabs70and flats68, an operator rotating front sleeve18rotationally drives the nut through first ring72, thereby opening or closing the jaws. When the operator rotates the sleeve/lock ring/nut in the closing direction (indicated by arrow90) to the point that the jaws tighten onto a tool shank, the nut is urged rearward up the jaw threads, thereby pushing the nut against inner race72, bearing elements76, outer race78, third ring91, and thrust ring46.

The wedge between the nut threads and jaw threads increasingly resists the rotation of the nut. When the operator continues to rotate front sleeve18in closing direction90, and the resistance overcomes the hold provided by biasing tabs96in second recesses104, front sleeve18rotates with respect to nut16and first ring72. This moves drive dogs64from sides110of grooves62to sides108and pushes biasing tabs98out of recesses100binto recesses100a(FIGS. 6B and 6C). Simultaneously, cam surfaces106rotate toward biasing tabs96so that the biasing tabs leave their respective second recesses104and ride up on the cam surfaces, thereby biasing first pawls86inwardly such that distal ends88of the pawls engage ratchet teeth84of ratchet ring79, as shown inFIG. 6C. At this point, first ring72, and therefore nut16, is rotationally locked to outer race78, and therefore chuck body14, against rotation in opening direction92of the chuck. That is, the nut is rotationally locked to the chuck body in the opening direction. Since the rotation of the nut with respect to the body is necessary to open the chuck, this resists inadvertent opening during use.

First ring72, and therefore nut16, may, however, still rotate with respect to outer race78, and therefore body14, in the closing direction90of the chuck. When the user rotates sleeve18, the sleeve drives nut16through drive dogs64against groove sides108, as well as through first ring72. This continues to tighten the chuck and, as described above, produces a clicking sound to notify the operator that the chuck is in a fully tightened position.

To open the chuck, the operator rotates front sleeve18in opening direction92. Front sleeve18transfers this torque to first ring72at the engagement of biasing tabs96on cam surfaces106and to third ring91at the engagement of biasing tabs98in recesses100. Because first pawls86engage ratchet ring79, which is rotationally fixed to the body via outer race78, through the ratchet teeth, first ring72cannot rotate with the front sleeve. Thus, upon application of sufficient torque in the opening direction92, front sleeve18moves with respect to the first ring and the nut. This moves first tabs96off of cam surfaces106and back into second recesses104, thereby disengaging distal ends88of respective first pawls86from ratchet teeth84. Biasing tabs98move from recesses100ainto recesses100b(FIG. 5), and drive dogs64move from sides108to sides110of grooves62. Thus, the front sleeve moves to the first position with respect to the nut, as shown inFIG. 6B, and the first ring and nut are free to rotate with respect to the outer race and chuck body. Accordingly, further rotation of front sleeve18in the opening direction moves jaws22away from the chuck axis, thereby opening the chuck.

It should be understood that the embodiment illustrated in the figures is provided by way of explanation only and that the present invention may be realized in any suitable form. For example, the pawls and ratchet may be formed in any suitable configuration. The present invention may be used in a variety of configurations whereby a bearing having a ratchet configuration is disposed between a sleeve, for example a nut or other suitable configuration, and the chuck body.

While one or more preferred embodiments of the present invention have been described above, it should be understood that any and all equivalent realizations of the present invention are included within the scope and spirit thereof. Thus, The depicted embodiment(s) are presented by way of example only and are not intended as limitations on the present invention. It should be understood that aspects of the various one or more embodiments may be interchanged both in whole or in part. Therefore, it is contemplated that any and all such embodiments are included in the present invention as may fall within the literal or equivalent scope of the appended claims.