Abstract:
The jaw mechanism has a plurality of jaw members or elements which are slidably disposed within corresponding channels defined in a rotatable body. A threaded body which is configured to be rotated either in a first or second direction is rotatably disposed about and engaged with the jaws. A thrust bearing assembly is configured to interface with the threaded body to rotate the threaded body to close the jaws when rotated. A dust cover is provided to cover the jaw mechanism. A grommet is provided which is annularly disposed about the bit to restrict dust from entering through the chuck jaw elements.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/654,860, filed on Feb. 18, 2005 and U.S. Provisional Application No. 60/654,852 filed on Feb. 18, 2005. The disclosure of the above applications is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to chucks and, particularly, to chucks having mechanisms configured to automatically engage a bit and, more particularly, to a duct cover for an automatic chuck.  
       BACKGROUND OF THE INVENTION  
       [0003]     Chuck members for tools have been developed which are configured to automatically engage and disengage drive or cutting elements or bits. One mechanism for engaging cutting bits utilizes a spring-loaded impact mechanism to rotate gripping teeth with respect to a threaded member relative to the rotating teeth to bring either into engagement or out of engagement with the cutting bit. Upon initialization by an operator, these impact mechanisms utilize forward and reverse drive forces from a motor to drive the jaw mechanism into and out of engagement with the drill bit. The operation of these chuck mechanisms are described in co-assigned U.S. Provisional Patent Application No. 60/654,852 by Gehret, et al., entitled “NON-SLIP REVERSE DEVICE FOR IMPACTING-TYPE CHUCK.  
         [0004]     These chuck mechanisms are however greatly affected by the deleterious effects of dust which become trapped within the chuck. This dust, which often evolves from the use of a cutting tool held by the chuck, becomes entrapped within the lubricants in the chuck and significantly reduces the operating life of the chuck mechanism.  
       SUMMARY OF THE INVENTION  
       [0005]     To overcome the deficiencies of the prior art, a chuck mechanism is disclosed having a user initiated tightenable jaw mechanism covered with a dust cover. This mechanism has a plurality of engageable jaws that are coupled to a rotatable socket member. An impact assembly is configured to interface with the socket member to prevent rotation of the socket member relative to a tool body. Rotation of the jaws in a first direction with respect to the selectively engageable socket allows the interaction of the jaws with the fixed socket member to close the jaws. Likewise, the jaws open when they are rotated with respect to the selectively engageable socket in a second direction. The dust cover covers the chuck mechanism and defines a bit accepting aperture which is co-axial with an aperture defined by the jaws.  
         [0006]     In another embodiment of the invention, an impact assembly for a user engageable chuck assembly is provided which is formed of an annular impact ring, a spring, and a spring bearing member. A mechanism is provided which is configured to position the spring at a first length when the jaws are rotated relative to the selectively engageable socket member in a first direction and a second length when the jaws are rotated with respect to the selectively engageable socket in a second direction. The variation of the spring length varies the force applied by the socket to the jaws. A dust cover is provided to cover the user initiated tightening chuck mechanism. The dust cover, which is non-rotatably fixed to a housing, defines a bit accepting aperture. A sealing grommet is optionally provided which is annularly disposed about the bit to least partially cover a portion of the jaw and at least partially covering the aperture. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0008]      FIGS. 1 and 2  represent tools utilizing the chuck dust cover according to the teachings of the prior art. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0009]     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0010]     As best seen in  FIG. 1 , a jaw assembly  26  for a cutting or drive assembly is shown. The jaw assembly  26  has an associated dust cover  64  that is configured to reduce the amount of foreign debris which can be incorporated into the jaw assembly. The jaw assembly  26  can have a center bit accepting through bore  24  formed therein, while an associated spindle  22  (not shown) can have a plurality of angularly disposed jaw accepting guideways formed therethrough that intersect the center through bore  24 . The rearward section of the spindle  22  can have a threaded hole, which is adapted to threadingly engage an output spindle of a power tool (not shown).  
         [0011]     The jaw assembly  26  has a plurality of jaw elements  32  which are movable from a first disengaged to a second engaged position. A selectively engaged socket member  28  is provided that is configured to drive the jaw elements  32  from the disengaged to the engaged position. An impact assembly  30  is configured to apply anti-rotational forces to the socket member  28 , which normally rotates with the spindle  22 . The impact assembly  30  has an impact ring, a spring, and a spring support member. The impact assembly  30  is configured to apply a first axial force and a first torsional force onto the socket member  28  when the impact assembly  30  is engaged and the socket member  28  is held fixed with respect to the jaw elements  32  which are being rotated in a first direction. Additionally, the impact assembly  30  is configured to apply a second axial and torsional force when the impact assembly  30  is engaged and when the jaw assembly  26  is rotated with respect to the selectively engageable socket member  28  in a second direction. A dust cover  64  is configured to cover the self-tightening mechanism. The dust cover  64  can be rotatably or non-rotatably coupled to a housing of the tool.  
         [0012]     The socket member or assembly  28  is annularly disposed about the jaw elements  32 . The socket  28  preferably defines an interior threaded bore, which is configured to interface with a threaded drive surface of the jaw elements  32 . Under normal operation of the tool, the socket  28  co-rotates with the jaw elements  32  and therefore does not move relative to the jaw elements  32 . To tighten or loosen the jaw elements  32 , the impact assembly  30  is engaged with the jaw assembly  26  is rotated relative to the intermittently fixed socket  28 .  
         [0013]     The relative rotation of the jaw assembly  26  with the fixed socket causes the jaw elements  32  to move together though the guideways in the spindle  22  when the jaw assembly  26  is rotated in a first or tightening direction with respect to the intermittently engageable socket  28 . Similarly, the chuck is disengaged when the jaw assembly  26  is rotated in a second or loosening direction relative to the socket  28 . The socket  28  can be formed of two rings ( 42  and  44 ). The first ring  42  having the interior threaded surface (not shown) and a ramp interface surface  53 . The second ring  44  has a ramped surface  50  configured to interface with the ramp interface surface  48  of the first ring  42  and a plurality of engagement teeth  52 .  
         [0014]     Upon engagement of the impact assembly  30  and rotation of the jaw assembly  26  in the second or loosening direction, the threaded engagement between the jaws  32  and first ring  42  will initially cause first ring  42  to also rotate in the second direction. Second ring  44 , however, will be restrained from rotation by the engagement between teeth  52  and teeth  57 . Thus, first ring  42  will rotate relative to second ring  44  and ramped leg  51  will slide into the shallow end  55  of ramped surface  50 . When ramped legs  51  are in the shallow end of ramped surface  50  there can be no further relative rotation between first ring  42  and second ring  44 . At that point, impact ring  54  effectively engages first ring  42  via teeth  52  and  57  and via second ring  44 . Since first ring  42  is then prevented from rotating, there will be relative rotation between first ring  42  and jaw assembly  26  causing jaws  32  to move outward as described.  
         [0015]     As seen in  FIG. 2 , when a predetermined amount of torque is thereafter applied to the spindle  22 , the socket  28  will begin to rotate with the spindle  22 , causing the socket teeth  52  to ride over the ring teeth  57  and urge the impacting ring  54  in a rearward direction away from the threaded socket  28 . Since the spring  58  biases the impacting ring  54  forwardly, the socket teeth  52  will periodically strike the ring teeth  57  as the threaded socket  28  rotates. The impact of the socket teeth  52  and the first ring teeth  57  will generate a torque that is applied to the threaded socket  28 . This tends to further urge the threaded socket  28  against the jaw members  32 . This results in the spring  58  applying a larger force to the impact ring  54  of the impact assembly  30 . This, in turn, results in an increased loosening torque applied to the jaw elements  32  and bit interface when the jaw elements  32  are disengaging a bit.  
         [0016]     During chucking, continued rotation of the jaw assembly  26  in the first or tightening direction will cause the rotationally coupled rings  42  and  44  to induce the reciprocating and impacting movement of impact ring  54  as previously described. The sloped interface  50  allows the interface ring  44  to move axially away from the spring bearing element  60  thus allowing the spring  58  to lengthen. This results in the spring  58  applying a smaller force to the impact ring  54  of the impact assembly  30 . This in turn results in a reduced tightening torque applied to the jaw elements  32  and bit interface when the jaw elements are engaging a bit.  
         [0017]     During unchucking of a drill bit, upon rotation of the jaw assembly  26  in the second or loosening direction, the threaded engagement between the jaws  32  and first ring  42  will initially cause first ring  42  to also rotate in the second direction. Second ring  44 , however, will be restrained from rotation by the engagement between teeth  52  and teeth  57 . Thus, first ring  42  will rotate relative to second ring  44  and ramped leg  51  will slide into the deep end  56  of ramped surface  50 . When ramped legs  51  are in the deep end of ramped surface  50  there can be no further relative rotation between first ring  42  and second ring  44 . At that point impact ring  54  effectively engages first ring  42  via teeth  52  and  57  and via second ring  44 . The socket  28  has a first thickness when rotated in the first direction and a second thickness when rotated in the second direction.  
         [0018]     Continued rotation of the jaw assembly  26  in the second or loosening direction will cause rotationally interlocked first ring  42  and second ring  44  to initially rotate along with the jaw assembly  26 . Rotation of second ring  44  will cause the socket teeth  52  to ride over the ring teeth  57  and urge the impacting ring  54  in a rearward direction away from the threaded socket  28 . Since the spring  58  biases the impacting ring  54  forwardly, the socket teeth  52  will periodically strike the ring teeth  57  as the threaded socket  28  rotates. The impact of the socket teeth  52  and the ring teeth  57  will generate a torque that will eventually overcome the static friction between the first ring  42  and jaws  32 , at which point the first ring will break free of the jaws. Further rotation of the jaw assembly  26  will result in relative rotation between jaws  32  and first ring  42 , since rotation of first ring  42  is resisted via the interlocked second ring  44 , teeth  52  and  57 , and impact ring  54 . The continued relative rotation between rotating jaws  32  and nonrotating first ring  42  will cause the jaws to move axially rearward and outward, thus releasing the bit from the chuck. Advantageously in this embodiment, since second ring  44  was forced rearward when ramped leg  51  moved to the deep end  56  of ramped surface  50 , spring  58  is compressed relative to its condition during chucking/tightening as described above. This results in the spring  58  applying a larger force to the impact ring  54  of the impact assembly  30  during unchucking. This in turn results in an increased loosening torque applied to the jaw elements  32  and bit interface when the jaw elements  32  are disengaging a bit.  
         [0019]     The dust cover  64  is provided which encapsulates the chuck mechanism  20 . The dust cover  64 , which is rotatably or non-rotatably coupled a body  66  of the tool, defines a bit accepting aperture  68 . As can be seen in  FIGS. 1 and 2 , the jaw elements  32  are positioned immediately adjacent the aperture  68 . The dust cover  64  has a generally cylindrical body and an end plate.  
         [0020]     To restrict the flow of dust into and through the aperture  68 , a grommet member  70  is optionally provided annularly disposed about the bit  72 . Additionally, the grommet member  70  on the bit  72  is positioned adjacent a proximal surface  80  of the dust cover  64 . In this regard, the grommet member  70  is positioned less than about 3 mm and preferably about 1 mm from the end plate of the dust cover  64 . The grommet  70  is additionally optionally positioned adjacent the jaw elements. The bit  72 , the grommet  70  and the jaw elements rotate together.  
         [0021]     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. For example, it is envisioned the dust cover can be utilized with any automatic chuck mechanisms such as those described in U.S. Provisional Application No. 60/654,852. Such variations are not to be regarded as a departure from the spirit and scope of the invention.