Abstract:
A liner for a power tool holder has a wall which defines an interior and an exterior periphery. The interior periphery is sized to receive a tool shaft and the exterior periphery is sized to fit within a tool holder. The liner protects the tool shafts from marring, nicking or the like while being frictionally held by the tool holder.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to power tools and, more particularly, to a liner to protect tools or bits from marring or nicking while in a tool holder of a power tool. 
     In power tools, specifically hobby tools, routers and rotating power tools, it is desirable to utilize various types of tools and/or bits. Ordinarily, these tools have some type of working head and an elongated shaft to be maintained in the power tool. Depending upon the tool head holder, the tool shafts are sized to be received in the holders. In the event that the tool shaft has a diameter, different than what is normally received by the tool holder, another tool holder is substituted on the power tool so that the tool may be retained in the power tool. 
     The tool holders utilize locking elements, such as balls, which are biased in the tool holder to maintain the tool in the holder. The elements apply a holding force onto the tool shafts to maintain the tools within the tool holder. In the event the biased elements are balls or the like, the balls may have a tendency to mar or nick the shaft of the tool. Thus, it is desirable to protect the tool shafts from marring, nicking or the like by the tool holders. 
     Accordingly, it is an object of the present invention to provide a liner which protects tools shafts from marring, nicking or the like. The liner of the present invention may also increases the friction holding force of the tool within the liner. 
     Accordingly, in accordance with a first aspect of the present invention, a liner for a tool holder comprises a hollow member with a wall defining an interior periphery and an exterior periphery. The interior periphery is sized to receive a tool and the exterior periphery is sized to fit within a tool holder. The hollow member includes two arcuate portions which define an elongated overall cylindrical configuration. Each arcuate portion includes at least one axial slot. The slots enable a reduced force to insert the tool into the hollow member. The exterior periphery of each arcuate member includes one or more axial grooves. A plurality of members project from the interior periphery of the hollow member to contact the tool. This provides increased frictional holding of the tool within the hollow member. The projection members surround the interior periphery to provide a corrugated pattern. One of the arcuate portions is thicker than the other. Both arcuate portions have the same thickness at their grooves so that the cam sleeve roll out tracks with the tool bit roll out. One arcuate portion defines an arc of about 200° and the other arcuate portion defines an arc of about 150°. 
     In accordance with a second embodiment of the present invention, a power tool comprises a housing with a motor within the housing. A power source is coupled with the motor. An output member is likewise coupled with the motor. An actuation member is coupled with the power source and the motor to power the motor which, in turn, rotates the output member. A tool holder is coupled with the output member. A tool, which includes a shank, is coupled with the tool holder. A liner is in the tool holder. The liner comprises a hollow member with a wall defining an interior periphery and an exterior periphery. The interior periphery is sized to receive a tool and the exterior periphery is sized to fit within a tool holder. The hollow member includes two arcuate portions which define an elongated overall cylindrical configuration. Each arcuate portion includes at least one axial slot. The slots enable a reduced force for inserting the tool into the hollow member. The exterior periphery of each arcuate member includes one or more axial grooves. A plurality of members project from the interior periphery of the hollow member to contact the tool. This provides increased frictional holding of the tool within the hollow member. The projection members surround the interior periphery to provide a corrugated pattern. One of the arcuate portions is thicker than the other. Both arcuate portions have the same thickness at the grooves. One arcuate portion defines an arc of about 200° and the other arcuate portion defines an arc of about 150°. 
     Additional objects and advantages of the invention will become apparent from the detailed description of the preferred embodiment, and the appended claims and accompanying drawings, or may be learned by practice of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a power tool with a tool and a liner in accordance with the present invention. 
     FIG. 2 is an exploded view of the tool and liner in accordance with the present invention. 
     FIG. 3 is a cross-section view of FIG. 1 along line  3 — 3  thereof. 
     FIG. 4 is a cross-section view of FIG. 3 along line  4 — 4  thereof. 
     FIG. 5 is an end view of the liner of FIG.  2 . 
     FIG. 6 is a perspective view of the liner of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning to the figures, particularly FIG. 1, a power tool is illustrated and designated with the reference numeral  10 . The power tool  10  is a rotary or router tool including a motor  12  which may be energized by a battery or cord  14 . An activation button  16  enables the power tool to be energized and rotates the motor  12 . The motor  12  has electrical connections between the activation button  16  and the power source  14  and are enclosed by a housing  18 . A tool holder  20  is coupled with an output spindle  22  of the power tool  10 . 
     The tool holder  20  includes a plurality of balls/rolls  24  which project through apertures  26  in the spindle  22 . A sleeve  28  which has a surface  30  in contact with the balls is biased by a spring  32  to maintain contact of the balls with the shaft  38  of the tool  40 . As can be seen in FIG. 2, a liner  50  surrounds a portion of the tool shaft  38  and is contacted by the balls  24  in the spindle bore. 
     The liner  50  may be manufactured from material harder than the shaft so that when force from the balls is applied onto the liner  50 , the shaft  38  will not be marred by the balls. 
     Turning to FIGS. 2-6, a better understanding of the liner  50  may be had. Liner  50  is comprised of two arcuate wall portions  52  and  54  which form the hollow cylindrical liner  50 . Both arcuate wall portions  52 ,  54  include an interior surface  56 ,  56 ′ and an exterior surface  58 ,  58 ′. The hollow liner  50  is elongated and has an overall cylindrical shape. The hollow liner  50  defines the longitudinal axis  60 . 
     The arcuate portion  52  defines an arc of about 200°. By going beyond 180°, the ends of the arcuate portion  52  force the arcuate portion  52  against the bore of the tool holder  20 . A complementary member  62  is at one axial end of the arcuate portion  52 . The complementary member  62  mates with a complementary member  64  in the second arcuate portion  54  to enable the two members to pivot along the longitudinal axis with respect to one another. At the other axial end, the arcuate portion  52  includes a projecting member  66 . The projecting member  66  is likewise arcuate and has an angled end  68  which is abutted by the tool holder sleeve to axially lock the arcuate portion  52  in position in the tool holder sleeve. 
     A pair of grooves  70  and  72  are on the external arcuate surface of the arcuate portion  52 . The grooves  70  and  72  are defined by a radius which is equal to or greater than the radius of the balls  24 . The two balls  24  are for friction reduction purposes and do not provide a clamping effect on the arcuate portion  52 . 
     The arcuate portion  52  also has a desired thickness. The thickness is greater than the thickness of the second arcuate portion  54 . The thickness at the grooves  70  and  72 , however, is the same as that at the groove of the second arcuate portion  54 . A plurality of slots  74 ,  76  and  78  are formed along the periphery of the arcuate portion  52 . Slots  74  and  78  are along the parting line or the sides of the arcuate portion  52 . Slot  76  is formed between slots  72  and  78  at approximately a 90° position along the arc. The slots  74 ,  76  and  78 , while enhancing the insertion of a tool within the liner  50 , also serve to retain rectangular cables of a flex cable for a rotary tool. Also, coined surfaces  80 ,  82  and  84  help to receive and maintain the rectangular cable in the liner  50 . 
     The second arcuate portion  54  is similar to arcuate portion  52 . However, the arc defined by the member  54  is about 150°. Also, as previously mentioned, at the one axial end, a complementary member  64  is contacted with complementary member  62  of the first arcuate portion  52  to enable pivoting of the second arcuate portion  54  with respect to the first arcuate portion  52 . The arcuate portion  54  is axially shorter than the arcuate portion  52  to enhance pivoting. Also, a gap of about 0.005 five thousandths inch is formed between the axial side edges of the arcuate portions  52  and  54 . This gap enables the arcuate portion  54  to be moved inward with respect to the fixed arcuate portion  52 . 
     The arcuate portion  54  includes a single ball groove  86  which is approximately positioned at a 90° position between the ends of the arcuate portion  54 . The ball riding in the groove clamps the arcuate portion  54  against the arcuate portion  52 . As mentioned, the groove  86  may be arcuate and be the same size as the ball or the radius slightly larger. The arcuate portion  54  has a thickness which is less than the thickness of the arcuate portion  52 . Also, a slot  88  is formed on the one axial end of the arcuate portion  54  to enhance insertion and enable retention of the rectangular cable as mentioned above. 
     The thickness of the arcuate portions  52  and  54  is important in controlling the parallel and angular run-out of the tool. By having thickness of the arcuate portion  54  less than the arcuate portion  52  and the thicknesses of the ball grooves the same, this enables the axis of the tool to be moved left or right off axis, yet still parallel to the axis of the tool holder. This is due in part to the variance or tolerance of the bore, tool shaft, and the arcuate portions  52  and  54 . By having the arcuate portions at an unequal thickness, it allows one of the arcuate portions to compensate for the tolerances of the above parts. By compensating for the tolerances, the arcuate portions in turn enable the axis of the tool to vary between a left limit and a right limit in the tool holder. Thus, the tool axis is at a much closer tolerance than would otherwise be had if the arcuate portions were at the same thickness. At the same thickness, the axis of the tool is to one side or the other in the tool holder but not from left to right as in the present invention. At one side or the other, the tolerance is much larger. It has been found that by having the thickness of the one arcuate portion with respect to the other of about three thousandths inch, that this will enable the axis of the tool to be moved left to right. Also, by having the groove thickness the same, this enables the outer chuck sleeve to track with the tool so that the sleeve runs left to right at a minimum like the tool. 
     Alternatively, the arcuate portions may include a plurality of alternating furrows  92  and ridges  98  which form a corrugated pattern about the periphery of the interiors of the arcuate portions. The ridges provide a friction surface which contacts the tool shaft and enhances the frictional holding of the tool shaft within the arcuate portions. 
     While the above detailed description describes the preferred embodiment of the present invention, the invention is susceptible to modification, variation, and alteration without deviating from the scope and fair meaning of the subjoined claims.