Abstract:
A chuck jaw that is configured and arranged to be used in combination with other chuck jaws for securely retaining a rotatable accessory, such as a drill bit, in position in a chuck assembly, where the chuck jaw includes a chuck jaw body that defines a generally longitudinal axis along the primary extension direction thereof and a chuck jaw tip that is positioned within the chuck jaw body and extends along at least a portion of the generally longitudinal axis of the chuck jaw body. The chuck jaw further includes an insulating material for preventing electrical current from passing between the rotatable accessory and the remainder of the chuck assembly via the chuck jaw.

Description:
The present invention relates generally to chuck jaws for use with a rotatable power tool, such as a drill, for securely retaining a rotatable accessory therein. More particularly, the present invention relates to an insulating chuck jaw that electrically insulates a rotatable accessory (such as a drill bit) from the chuck assembly, and therefore prevents electric current from being conveyed from the rotatable accessory to the user. 
     BACKGROUND OF THE INVENTION 
     Rotatable power tools, such as electric drills, are often used in situations where the rotatable accessory may come into contact with a source of electricity. For example, the drill bit of a power drill may sever a wire located within a wall, or the drill may even cut into its own cord. Accordingly, for the safety of the tool operator, it is important to prevent the electric current from reaching the operator. 
     One known method of preventing electric current from reaching the operator includes the use of an insulating housing with insulated hand grip areas. Another known method, which is described in U.S. Pat. No. 3,685,843 to Anthony Jacyno, involves the use of an insulating member that is positioned within a metal drill chuck, for preventing flow of electric current between the drill chuck and the rotating spindle. A similar type of insulating sleeve is also described in U.S. Pat. No. 3,797,960 to Donald J. McCarthy. 
     One problem with these known insulating methods is that there is still a danger of electric shock if the operator&#39;s hand or other body part contacts the chuck assembly while the rotatable accessory is in contact with the electrical wire. While these prior art insulating methods do insulate between the drill bit and the handle of the device, they usually fail to insulate between the drill bit and the chuck assembly (which holds the drill bit in position). Thus, the electric current is free to flow from the drill bit, to the chuck assembly, and then to the operator if, for example, the operator&#39;s hand makes contact with the chuck assembly, which is normally made of metal. 
     Accordingly, it is an object of the present invention to provide an improved rotatable power tool which provides insulated components therein for preventing electric current from being transferred from the rotatable accessory to the operator. 
     Another object of the present invention is to provide an improved chuck assembly which is insulated in such a manner that prevents electric current from being transferred from a rotatable accessory to the outer surface of the chuck assembly. 
     An additional object of the present invention is to provide an improved insulated chuck assembly that is inexpensive and can be utilized with existing chuck assembly configurations. 
     Yet another object of the present invention is to provide an insulating chuck jaw that can be used, in combination with other similar chuck jaws, in a chuck jaw assembly for providing superior electrical insulation therein. 
    
    
     These and other objects of the present invention will be apparent from the following detailed description of the invention, while referring to the attached drawings in which: 
     FIG. 1 is a side view of a rotatable power tool including therein several of the present insulating chuck jaws; 
     FIG. 2 is a partial cross-sectional view of a chuck jaw assembly including therein several of the present insulated chuck jaws; 
     FIG. 3 is a perspective view of a first embodiment of the present insulating chuck jaw; 
     FIG. 4 is a front view of the longitudinal end of the first embodiment of the present insulating chuck jaw; 
     FIG. 5 is a side view of the first embodiment of the present insulating chuck jaw; 
     FIG. 6 is a cross sectional view of FIG. 5 taken along line VI—VI; 
     FIG. 7 is a perspective view of a second embodiment of the present insulating chuck jaw; 
     FIG. 8 is a front view of the longitudinal end of the second embodiment of the present insulating chuck jaw; 
     FIG. 9 is a side view of the second embodiment of the present insulating chuck jaw; 
     FIG. 10 is a cross-sectional view of FIG. 9 taken along line X—X; 
    
    
     The above-listed objects are met or exceeded by the present invention, which provides an improved chuck jaw in a chuck assembly of a rotatable power tool that prevents electrical current from being transferred between a rotatable accessory and the operator, even if the operator makes contact with the outer surface of the chuck assembly. One of the main features of the present invention is an insulating chuck jaw that it intended to be used in combination with other similar insulating chuck jaws. Generally, the present invention consists of an insulating chuck jaw with a chuck jaw tip that is preferably made of metal and is configured to make secure contract with a rotatable accessory, such as a drill bit. The chuck jaw tip is at least partially surrounded by an insulating material such that electric current cannot be passed from the chuck jaw tip to the remainder of the chuck assembly. 
     More specifically, the present invention provides a chuck jaw that is configured and arranged to be used in combination with other chuck jaws for securely retaining a rotatable accessory in position in a chuck assembly, where the chuck jaw includes a chuck jaw body that defines a generally longitudinal axis along the primary extension direction thereof and a chuck jaw tip that is positioned within the chuck jaw body and extends along at least a portion of the generally longitudinal axis of the chuck jaw body. The chuck jaw further includes an insulating material for preventing electrical current from passing between the rotatable accessory and the remainder of the chuck assembly via the chuck jaw. 
     In a first preferred embodiment, the insulating material consists of a generally channel-shaped component that is situated between the chuck jaw tip and the chuck jaw body. In a second preferred embodiment the insulating material forms the majority of the chuck jaw body, and the chuck jaw tip is embedded, at least partially, therein. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, the first preferred embodiment of the present invention is shown in FIGS. 1-6, with FIG. 1 showing a power drill  10 . Power drill  10  is one example of the type of rotatable power tool that may employ the present insulated chuck jaw. Briefly, the power drill  10  includes a housing  12 , which is preferably made of plastic, that includes a handle portion  14  and an on/off trigger  16 . Located within the housing  12  is a motor (not shown), which is connected to a rotatable shaft  18 . The rotatable shaft  18  is further rotatably connected to a chuck assembly  20 , which is still further rotatably connected to a drill bit  24 . The drill bit  24  is secured in place within the chuck assembly  20  for rotation therewith via a plurality of chuck jaws  22 . 
     To operate the drill  10 , the user grips the handle  14  and presses the on/off trigger  16  to start rotation of the motor located within the housing  12 . The motor rotates the rotatable shaft  18 , the chuck assembly  22 , and the drill bit  24  because all of these components are rotatably connected together. 
     Referring now to FIG. 2, a partially cut-away view of the chuck assembly  20  is shown. The rotatable shaft  18  is externally threaded so that it can be secured to internally threaded body part  26  for rotation therewith. The threaded body part  26  includes therein a central bore  27  for receiving the drill bit  24 . The threaded body part  26  also includes a plurality of equally spaced bores  28 , which are inclined toward the central bore  27 . Preferably, the body part  26  includes three bores  28 . One chuck jaw  22  is seated within each of the bores  28 . An internally threaded nut  30  is configured to surround the chuck jaws  22 . Each of the chuck jaws  22  includes a threaded portion  32  that extends along at least a portion of its outer periphery. The nut  30  is preferably formed in half to facilitate assembly around the chuck jaws  22 , and a sleeve  34  is preferably used to retain the two halves of the nut in position. 
     The sleeve  34  and the nut  30  are configured to be rotatable together, such as via an interference fit or by having the nut  30  keyed into the sleeve  34 . The threads of the nut  30  are configured to mate with the threads  32  of the chuck jaws  22 . A chuck body  36  in the form of a tapered sleeve is positioned adjacent to the nut  30  and surrounds the chuck jaws  22 . 
     As known to those skilled in the art, the chuck jaws  22  may be extended (for gripping the drill bit  24 ) or retracted (for releasing the drill bit) through the use of a ratcheted key (not shown) that can be inserted into a key port  38  that is recessed within the chuck body  36 . More specifically, the key is rotated within the key port  38  such that the teeth located on the key contact the key ratchets  40  on the sleeve  34 . When the key is rotated, the sleeve  34  rotates, which in turn causes the nut  30  to rotate, resulting in the extension or retraction of the chuck jaws  22  due to the threaded connection between the nut  30  and the threads  32  of the chuck jaws. 
     One important aspect of the present invention is the configuration of the chuck jaws  22 . Referring now to FIGS. 3-6, the configuration of a first embodiment of the chuck jaws  22  will now be described. As shown in FIG. 3, the chuck jaw  22  of this embodiment includes a chuck body jaw  42  and a chuck jaw tip  44 . The chuck jaw body  42  includes a cutaway portion  48  which is peaked such that a generally V-shaped cross-section is formed, as can be seen in FIGS. 3,  4 , and  6 . 
     This embodiment also preferably includes a generally channel-shaped member  46  made of an insulating material such as plastic. Preferably, the chuck jaw body  42  and the chuck jaw tip  44  are both made of metal in order to provide sufficient strength to the chuck jaw  22 . In the preferred embodiment, the chuck jaw tip  44  and the channel shaped member  46  extend the full length of the chuck jaw body  42 . However, it is contemplated that the chuck jaw tip  42  and the channel-shaped member may terminate within the chuck jaw body  42  at a position just past the cutaway portion  48 . For reasons that will become apparent, the chuck jaw tip  44  needs to be completely electrically insulated from the chuck jaw body  42 . Accordingly, if the chuck jaw tip  44  does not extend the full length of the chuck jaw body  42 , the insulating channel-shaped member  46  must include an end cap that prevents the end of the tip  44  from contacting the jaw body  42 . Likewise, if the chuck jaw tip  44  does extend the full length of the chuck jaw body  42 , the top of the tip  44  in the area past the cutaway portion  48  must be fully enclosed within the channel shaped member  46  to prevent contact between the tip  44  and the chuck jaw body  42 . 
     The chuck jaw tip  44  is preferably adhesively bonded to the channel-shaped member  46 , and the channel-shaped member  46  is preferably adhesively bonded to the chuck jaw body  42 . In order to provide a more secure bond between the channel-shaped member  46  and both the chuck jaw body  42  and the chuck jaw tip  44 , a mechanical interlock may be formed between these components. This mechanical interlock may be used in addition to the adhesive, or in place of the adhesive, if desired. More specifically, as shown in FIG. 6, a mechanical interlock is formed between the channel-shaped member  46  and the chuck jaw body  42  by forming a generally dovetail-shaped interface therebetween. This dovetail-shaped interface includes a seating surface  50  recessed within the chuck jaw body  42  that corresponds to the outer perimeter  52  of the channel-shaped member  46 . The mechanical interlock securing the chuck tip  44  is preferably formed of a similar dovetail-shaped interface between a seating surface  54  recessed within the channel-shaped member  46  that corresponds to the outer periphery  56  of the chuck tip  44 . While one example of corresponding shapes suitable for use as a mechanical interlock has been shown and described, it is contemplated that mechanical interlocks of other shapes may also be utilized, such as those with multiple dovetail-shaped interfaces or with interfaces of complementary teeth of other shapes. 
     An important feature of the present invention is the manner in which the chuck jaws  22  prevent electric current from being transferred from the drill bit  24  to the remainder of the drill  10 . When the drill bit  24  is secured in position by the chuck jaws  22 , as shown in FIGS. 1 and 2, the metal chuck jaw tips  44  of each jaw  22  are contacting the drill bit  24 . Thus, any current that travels through the drill bit  24  (which is usually metal) will reach the chuck jaw tips  44 . However, because each of the jaw tips  44  are completely insulated from its associated chuck jaw body  42  by its channel-shaped member  46 , the electric current does not pass through to the chuck jaw body  42 . Accordingly, the electric current does not pass through to the remainder of the drill  10 . Thus, even if the operator makes contact with the metal sleeve  34  or metal chuck body  36  of the chuck assembly  20  while the drill bit  24  is conducting an electric current, the operator should not receive that current. 
     Turning now to FIGS. 7-10, a second preferred embodiment of the present insulated chuck jaws will now be described. For the sale of convenience, corresponding features of this embodiment have been given the same index numbers as those features of the first embodiment, with the addition of the prime symbol to each index number in the second embodiment. 
     In this embodiment, there is no channel-shaped insulating member (member  46  of the first embodiment). Instead, the entire chuck jaw body  42 ′ is formed of an insulating material. Thus, the chuck tip  44 ′, which is preferably formed of metal, is seated directly within the chuck jaw body  42 ′. Because the chuck jaw body  42 ′ is formed of an insulating material, it prevents electric current from passing through the chuck jaw tip  44 ′ to the remainder of the drill  10 . 
     As in the first embodiment, the components of this second embodiment are preferably secured together with adhesive, or with a mechanical interlock, or both. More specifically, the mechanical interlock may include a generally dovetail-shaped interface between a seating surface  54 ′ of the chuck body  42 ′ and the outer periphery  56 ′ of the chuck jaw tip  44 ′. Of course, other shapes for surfaces of the mechanical interlock are also contemplated. 
     In this embodiment, the chuck jaw tip  44 ′, which is preferably made of metal, preferably extends for the full length of the chuck jaw body  42 ′ to provide additional strength to the chuck jaw body  42 ′, which is preferably made of plastic. However, if the chuck jaw body  42 ′ can be made of a material of sufficient strength, while still providing the necessary insulating qualities, the chuck jaw tip  44 ′ need not extend for the full length of the chuck jaw body  42 ′, and instead, for example, may terminate at a point near the end of the cutaway portion  48 ′. 
     In operation, the second embodiment of the chuck jaw  22 ′ provides the same beneficial insulating properties as the first embodiment. Thus, the insulating chuck jaw body  42 ′ prevents current from being transferred from the chuck tip  44 ′ to the remainder of the drill  10  (or other rotatable power tool). 
     While various embodiments of the present invention have been shown and described, it should be understood that other modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the invention, which should be determined from the appended claims. 
     Various features of the invention are set forth in the appended claims.