Patent Application
20140077463
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.
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 onto 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.
As well, many of these keyless chucks have been developed which include a locking feature that prevents inadvertent loosening, or possible opening, of the jaws. Many of these locking features require that an outer sleeve rotate relative to one or more spring-like pawls that are typically non-rotatably fixed to the nut. Through rotation of the sleeve relative to the pawls, the pawls can be made to either engage or disengage locking teeth that are fixed to the chuck body in some manner Because the sleeve must rotate relative to the pawls and nut, the sleeve cannot be press fit to the nut. Rather, the sleeve is typically, at least partially, supported on the pawls the sleeve operates. As noted, because the pawls must be movable radially inwardly and outwardly to function, they typically have a spring-like construction. Support of the outer sleeve on the spring-like pawls can lead to undesired radial motion, or wobbling, during normal operation of the chuck.
To assist in preventing this undesired motion, some chucks include dust caps which are typically press-fit to a rear portion of the chuck body and have an outer perimeter that forms a gap with an inner surface of the rear perimeter of the sleeve. The size of this gap helps to limit the amount of radial motion of the sleeve relative to the chuck body. However, difficulties in manufacturing close tolerances between the outer perimeter of the dust cap and rear perimeter of the sleeve exist due to the size of the components. As well, it is not uncommon for the rear perimeter of the sleeves in these types of chucks to be slightly out-of-round due to the materials they are constructed from and the fact that the rear perimeter of the sleeve does not receive any direct structural support.
The present invention recognizes and addresses the foregoing considerations, and others, of prior art constructions and methods.
One embodiment of a chuck in accordance with the present disclosure includes a generally cylindrical body having a nose section and a tail section, the tail section being configured to rotate with the drive shaft and the nose section having an axial bore formed therein, a plurality of jaws movably disposed with respect to the body in communication with the axial bore, a sleeve 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, the sleeve defining an annular groove adjacent its rear perimeter, a rear cover defining an annular ridge extending radially outwardly from its annular outer surface, the annular ridge being received in the annular groove of the sleeve, and a bearing having a first race adjacent the body, a second race adjacent the sleeve and at least one bearing element disposed between the first race and the second race. One of the first race and the second race defines a ratchet, wherein the other of the first race and the second race defines a pawl, and the ratchet and the pawl are configured so that when the pawl engages the ratchet, the ratchet and pawl prevent the second race from rotating in the opening direction with respect to the first race.
Another embodiment of a chuck in accordance with the present disclosure includes a body having a nose section and a tail section, the tail section being configured to rotate with the drive shaft and the nose section having an axial bore formed therein, a plurality of jaws movably disposed with respect to the body in communication with the axial bore, a sleeve 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, the sleeve defining a recess adjacent its rear perimeter, a rear cover defining a projection extending radially outwardly from its annular outer surface, the projection being received in the recess of the sleeve, and a bearing having a first race adjacent the body, a second race adjacent the sleeve and at least one bearing element disposed between the first race and the second race, wherein one of the first race and the second race defines a ratchet. The other of the first race and the second race defines a pawl, and the ratchet and the pawl are configured so that when the pawl engages the ratchet, the ratchet and pawl prevent the second race from rotating in the opening direction with respect to the first race.
Yet another embodiment of a chuck in accordance with the present disclosure includes a body having a nose section and a tail section, the tail section being configured to rotate with the drive shaft and the nose section having an axial bore formed therein, a plurality of jaws movably disposed with respect to the body in communication with the axial bore, a nut 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 sleeve rotatably mounted about the body in operative communication with the nut, the sleeve defining an annular groove adjacent its rear perimeter, a rear cover received in the sleeve in a press-fit adjacent a rear perimeter of the sleeve, and a bearing having a first race adjacent the body, a second race adjacent the sleeve and at least one bearing element disposed between the first race and the second race. One of the first race and the second race defines a ratchet, wherein the other of the first race and the second race defines a pawl, and the ratchet and the pawl are configured so that when the pawl engages the ratchet, the ratchet and pawl prevent the second race from rotating in the opening direction with respect to the first race.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, which makes reference to the accompanying figures, in which:
Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention.
Reference will now be made in detail to presently preferred embodiments of the disclosure, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present disclosure without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Referring to
Body 14 defines three passageways 40 to accommodate three jaws 22. Each jaw is separated from the adjacent jaw by an arc of approximately 120°. The axes of passageways 40 and jaws 22 are angled with respect to the chuck center axis 30 such that each passageway axis travels through axial bore 34 and intersects axis 30 at 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 jaw 22 has a tool engaging face 42 generally parallel to the axis of chuck body 14. Threads 44, formed on the jaw's opposite or outer surface, may be constructed in any suitable type and pitch.
As illustrated in
Nose piece 20 retains nut 16 against forward axial movement. The nose piece is press fit to body nose section 24. 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, such as by a band holding the two pieces together. Nose piece 20 may 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.
Outer sleeve 18 is secured from movement in the forward axial direction by an annular shoulder 91 on nose piece 20. A frustoconical section 95 at the rearward end of the nose piece facilitates movement of jaws 22 within the chuck. As well, the outer circumferential surface of outer sleeve 18 may be knurled or may be provided with longitudinal ribs 77 or other protrusions to enable the operator to grip it securely.
Additionally, the inner surface of outer sleeve 18 defines an annular groove 23 adjacent its rear perimeter 25. Annular groove 23 is configured to receive an annular ridge 19 extending radially outwardly from an outer annular wall 17 of rear cover 12. Rear cover 12 includes an inner annular wall 15 that defines a bore 21 that is configured to be slidably and rotatably received about rearward section 26 of chuck body 14. After outer sleeve 18 has been positioned over chuck body 14 and retained in the forward axial direction by nose piece 20, rear cover 12 is pressed into the rear perimeter 25 of outer sleeve 18 until annular ridge 19 is received in annular groove 23 in a snap-fit. So positioned, rear cover 12 serves to maintain the circular shape of rear perimeter 25 of outer sleeve 18. As well, the reduced size of bore 21 and rear portion 26 of the chuck body, as opposed to the outer perimeter of a dust cover and rear perimeter of a sleeve on a typical chuck, allow for improved accuracy of manufacturing a gap between bore 21 and the rear portion of chuck body 14 to the desired tolerances. As such, since the gap between annular inner wall 15 and the outer surface of rear portion 26 can be manufactured with increased accuracy, unwanted radial motion of outer sleeve 18 relative to chuck body 14 can be reduced, as compared to typical locking chucks.
The outer sleeve may 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. Additionally, the outer sleeve may be fabricated from various metals. As should be appreciated by one skilled in the art, the materials for which the chuck of the present invention is fabricated will depend on the end use of the chuck, and the above materials are provided by way of example only.
Nut 16 has threads 56 for mating with jaw threads 44. Nut 16 is positioned about the body in engagement with the jaw threads so that when the nut is rotated with respect to body 14, the jaws will be advanced or retracted depending on the nut's rotational direction.
As illustrated in
Nut 16 also defines a plurality of grooves formed as flats 68 about the nut's outer circumference. Flats 68 receive respective tabs 70 extending forward from an inner race 72 of a bearing assembly 74. The engagement of tabs 70 and flats 68 rotationally fix the inner race to the nut, although it should be understood that there may be a slight rotational tolerance between the two.
Inner race 72 receives a plurality of bearing elements 76, in this case bearing balls, disposed between it and an outer race 78 seated on thrust ring ledge 50 (
Outer race 78 also includes a ratchet. In the illustrated embodiment, the ratchet is formed by a plurality of sawtooth-shaped teeth 84 disposed about the inner circumferential surface of the outer race. A first pawl 86 extends from one side of each tab 70 and is biased radially outward from the inner race, thereby urging a distal end 88 of each first pawl 86 toward the outer race ratchet.
Each tooth 84 has a first side with a slope approaching 90°. The second side has a lesser slope. First pawl 86 is deflectable and is generally disposed in alignment with the slope of the second side. Thus, rotation of inner race 72 in a direction 90 with respect to outer race 78 moves first pawl distal ends 88 repeatedly over teeth 84, causing a clicking sound as ends 88 fall against each subsequent tooth's second side. This configuration of teeth 84 and first pawl 86, however, prevents the inner race's rotation in an opposite direction 92. Application of rotational force to the inner race in this direction forces distal ends 88 into the steep-sloped first sides of teeth 84. Since first pawl 86 is generally perpendicular to the first sides, it does not deflect inward to permit rotation.
As discussed below, direction 90 corresponds to the chuck's closing direction, while direction 92 corresponds to the chuck's opening direction. Accordingly, when first pawls 86 engage ratchet teeth 84, the teeth permit the inner race's movement in the chuck's closing direction 90 but prevent its movement in the opening direction 92.
A second deflectable pawl 94 extends to the other side of each tab 70. Like first pawls 86, each second pawl 94 is biased radially outward. Unlike first pawls 86, however, second pawls 94 do not engage the outer race ratchet.
First and second pawls 86 and 94 include tabs 96 and 98 at their distal ends, respectively. Referring also to
Referring now to
As described in more detail below, when outer sleeve 18 rotates in opening direction 92 so that the inner race moves from the engaged position shown in
In operation, and referring to
The wedge between the nut threads 56 and jaw threads 44 increasingly resists the nut's rotation. When the operator continues to rotate outer sleeve 18, and the resistance overcomes the hold provided by tabs 98 in recesses 100, outer sleeve 18 rotates with respect to nut 16 and inner bearing race 72. This moves drive dogs 64 from sides 110 of grooves 62 to sides 108 and pushes tabs 98 out of recesses 100 into recesses 102. Simultaneously, cam surfaces 106 rotate away from tabs 96 so that the tabs are released into recesses 104, thereby engaging distal ends 88 of first pawls 86 with ratchet teeth 84, as shown in
Inner race 72, and therefore nut 16, may, however, still rotate with respect to outer race 78, and therefore body 14, in the chuck's closing direction 90. During such rotation, sleeve 18 drives nut 16 through drive dogs 64 against groove sides 108, as well as through inner race 72. 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 outer sleeve 18 in the opposite direction. Outer sleeve 18 transfers this torque to inner race 72 at the engagement of tabs 96 and 98 in recesses 104 and 102, respectively. Because first pawls 86 engage outer race 78, which is rotationally fixed to the body, through the ratchet teeth, the inner race cannot rotate with the outer sleeve. Thus, upon application of sufficient torque in the opening direction 92, outer sleeve 18 moves with respect to the inner race and the nut. This moves tabs 96 back up onto cam surfaces 106, thereby disengaging distal ends 88 of first pawls 86 from ratchet teeth 84. Tabs 98 move from recesses 102 into recesses 100, and drive dogs 64 move from sides 108 to sides 110 of grooves 62. Thus, the sleeve moves to its first position with respect to the nut, as shown in
Referring now to
In operation, and referring to
The wedge between nut threads 56 and jaw threads 44 increasingly resists the nut's rotation. When the operator continues to rotate outer sleeve 18, and the resistance overcomes the hold provided by tabs 98 in recesses 100, sleeve 18 rotates with respect to nut 16 and inner bearing race 72. This moves drive dogs 64 from sides 110 of grooves 62 to sides 108 and pushes tabs 98 out of recesses 100 into recesses 102. Simultaneously, cam surfaces 106 rotate away from tabs 96 so that the tabs are released into recesses 104, thereby engaging distal ends 88 of first pawls 86 with ratchet teeth 84, as shown in
Inner race 72, and therefore nut 16, may, however, still rotate with respect to outer race 78a, and therefore body 14, in the chuck's closing direction 90. During such rotation, sleeve 18 drives nut 16 through drive dogs 64 against groove sides 108, as well as through inner race 72. 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 outer sleeve 18 in the opposite direction. Sleeve 18 transfers this torque to inner race 72 at the engagement of tabs 96 and 98 in recesses 104 and 102, respectively. Because first pawls 86 engage outer race 78a, which is rotationally fixed to the body by frictional force, through the ratchet teeth, the inner race cannot rotate with the sleeve. Thus, upon application of sufficient torque in opening direction 92, outer sleeve 18 moves with respect to the inner race and the nut. This moves tabs 96 back up onto cam surfaces 106, thereby disengaging distal ends 88 of first pawls 86 from ratchet teeth 84. Tabs 98 move from recesses 102 into recesses 100, and drive dogs 64 move from sides 108 to sides 110 of grooves 62. Thus, the outer sleeve moves to its first position with respect to the nut, as shown in
In an alternate embodiment of the chuck, inner periphery 81 of outer race 78a and second surface 49 of ledge portion 50 are sized such that outer race 78a is received about body in a press-fit. This embodiment functions in a manner similar to that shown in
While one or more preferred embodiments of the present disclosure have been described above, it should be understood that any and all equivalent realizations of the present disclosure 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. It should be understood that aspects of the various one or more embodiments may be interchanged either in whole or in part. Therefore, it is contemplated that any and all such embodiments are included in the present disclosure as may fall within the literal or equivalent scope of the appended claims.
This application claims priority to U.S. Provisional Patent Application No. 61/702,777 filed Sep. 19, 2012, the entire disclosure of which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61702777 | Sep 2012 | US |
