Abstract:
An extended tool holder for holding a cutting tool and receivable within a standard tool holder is provided. The extended tool holder comprises a body having a shank portion and a collet-receiving portion with an aperture extending through the body. A collet is receivable within the collet-receiving portion of the hollow body with the collet having a plurality of fingers closable about at least a portion of the cutting tool. A draw bolt is receivable within the shank portion of the hollow body and connected to the collet for urging the collet into collet receiving portion of the body wherein upon the collet entering the collet receiving portion, the fingers close about the cutting tool.

Description:
[0001]    The present application is a continuation and claims priority of pending U.S. provisional patent application Ser. No. 60/482,341, filed on Jun. 25, 2003, entitled “Extended Tool Holder with Draw Collet”. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates generally to a tool holder and, more particularly, the invention relates to an extended tool holder with draw collet which employs a through-the-body draw bolt for reducing bulkiness of the collet nut and inhibiting loosening due to vibration forces that are applied to the unsupported end of the tool holder.  
           [0004]    2. Description of the Prior Art  
           [0005]    Machine tools such as milling machines and lathes typically hold cutters in universal adapters called tool holders. The tool holders are universal in that they are designed for various machine tools, operations, cutter sizes, and styles. Typically, these tool holders work well for most applications but, there are some applications where the standard tool holder will not suffice and a specialized tool holder must be employed.  
           [0006]    Specialized tool holders are commonly employed where it is impractical to use a standard tool holder such as operations to cut deep pockets or holes where reach is an issue and/or the size of the cutter is too small.  
           [0007]    Conventional tool holders have limitations in some applications and in their design. For instance, a commonly used extended tool holder has significant drawbacks in the way the tool holder restrains the cutter. The conventional tool holder employs an external nut to compress the collet which, in turn, tightens around the cutting tool shank. This design has two weaknesses in that the compressing nut increases the size of the tool holder end and the nut can be loosened by vibration. Another type of extended tool holder that does not use a collet, holds the cutter by shrink fit. Although this design overcomes the above listed faults, it is still impractical and inconvenient in use to the machinist in that user must heat the holder and/or cool the cutter in order to get them to shrink fit rigidly together.  
           [0008]    Accordingly, there exists a need for an extended tool holder with a draw collet which overcomes the drawbacks of conventional tool holders by employing a through-the-body draw bolt that reduces the bulkiness of the collet nut and also inhibits loosening due to vibration forces that are applied to the unsupported end of the tool holder. Additionally, a need exists for an extended tool holder with a draw collet that does not require apparatuses and facilities for heating and cooling of the tools in order to achieve a shrink fit.  
         SUMMARY  
         [0009]    The present invention is an extended tool holder for holding a cutting tool and receivable within a standard tool holder. The extended tool holder comprises a body having a shank portion and a collet-receiving portion with an aperture extending through the body. A collet is receivable within the collet-receiving portion of the hollow body with the collet having a plurality of fingers closable about at least a portion of the cutting tool. A draw bolt is receivable within the shank portion of the hollow body and connected to the collet for urging the collet into collet receiving portion of the body wherein upon the collet entering the collet receiving portion, the fingers close about the cutting tool.  
           [0010]    In addition, the present invention includes a method for holding a cutting tool and receivable within a standard tool holder. The method comprises providing a body having a first end and a second end, inserting a collet into the first end of the body, the collet having a plurality of flexible fingers, inserting a draw bolt into the second end of the body, threadably connecting the collet to the draw bolt, tightening the draw bolt into the collet, urging the collet into the first end of the body, and tightening the fingers of the collet about the cutting tool.  
           [0011]    The present invention further includes an apparatus for holding an object. The apparatus comprises a holder having a first end and a second end, an aperture extending from the first end to the second end, collet means for holding the object, and draw means connected to the collet means for tightening the collet means about the object. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 a  is a front perspective view illustrating an extended tool holder with draw collet, constructed in accordance with the invention;  
         [0013]    [0013]FIG. 1 b  is a rear perspective view illustrating the extended tool holder with draw collet, constructed in accordance with the present invention;  
         [0014]    [0014]FIG. 2 a  is a front perspective exploded view illustrating the components of the extended tool holder with draw collet, constructed in accordance with the invention;  
         [0015]    [0015]FIG. 2 b  is a rear perspective exploded view illustrating the components of the extended tool holder with draw collet, constructed in accordance with the present invention;  
         [0016]    [0016]FIG. 3 a  is a top sectional view illustrating the extended tool holder with draw collet, constructed in accordance with the invention;  
         [0017]    [0017]FIG. 3 b  is an end sectional view illustrating the extended tool holder with draw collet, constructed in accordance with the present invention;  
         [0018]    [0018]FIG. 3 c  is an elevational side view illustrating the extended tool holder with draw collet, constructed in accordance with the present invention;  
         [0019]    [0019]FIG. 4 a  is a front perspective view illustrating the collet component of the extended tool holder with draw collet, constructed in accordance with the invention; and  
         [0020]    [0020]FIG. 4 b  is a rear perspective view illustrating the collet component of the extended tool holder with draw collet, constructed in accordance with the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]    As illustrated in FIGS. 1 a  and  1   b , the present invention is an extended tool holder, indicated generally at  10 , which fits into a standard tool holder (not shown) allowing a cutting tool (not shown) to be held in a manner that is practical for the application. While the extended tool holder  10  of the present invention has been and will be described as holding a cutting tool such as a drill bits, boring bars, reamers, end mills, etc., it is within the scope of the present invention for the extended tool holder  10  to hold any type of tool within any type of standard tool holder.  
         [0022]    The extended tool holder  10  has a body  12  for enclosing a collet  14  and a draw bolt  16 . Preferably, the collet  14  is tapered corresponding to the taper of an aperture  18  within the body  12 . As illustrated in FIGS. 2 a  and  2   b , the body  12  of the extended tool holder  10  accepts the collet  14  and the draw bolt  16  in a concentric fashion.  
         [0023]    The body  12  of the extended tool holder  10  of the present invention includes a shank portion  20  having a first end  22  and a second end  24  and a collet-receiving portion  26  having a first end  28  and a second end  30 . Preferably, the collet-receiving portion  26  of the body  12  is tapered from the first end  28  to the second end  30 . The aperture  18  extends through the body  12  from the first end  22  of the shank portion  20  to the second end  30  of the collet-receiving portion  26 . Preferably, the aperture  18  is tapered within the collet-receiving portion  26  for receiving the tapered collet  14 .  
         [0024]    As illustrated in FIGS. 3 a - 3   c , the tapered collet  14  is receivable within the aperture  18  of the tapered collet-receiving portion  26  of the body  12 . The draw bolt  16  fits through the aperture  18  within the shank portion  20  of the body  12  and threads into a threaded aperture  32  of the collet  14 . The shank portion  20  of the body  12  of the extended tool holder  10  preferably has at least one flat area  34  formed therein for locking and orienting the body  12  of the extended tool holder  10  in the chuck (not shown) or the machine tool holder. Additional flat areas  35  are preferably positioned radially on the tapered collet-receiving portion  26  of the extended tool holder  10 .  
         [0025]    As illustrated in FIGS. 4 a  and  4   b , the end  36  of the collet  14  includes a plurality of flexible fingers  38  which are manifested by axial slots  40  terminating at a strain relief spot  42 . A tapered portion  44  is provided on the outside diameter of the collet  14  and terminates at a relieved portion  46 . A raised portion  48  is the shank of the collet  14 . The threaded aperture  32  is provided to a predetermined depth in the collet  14  for receiving at least portion of the draw bolt  16 .  
         [0026]    In operation of the extended tool holder  10  of the present invention, a user uses the draw collet extended tool holder  10  in conjunction with a machine tool holder (not shown). The shank portion of a cutting tool (not shown) is firmly held by the extended tool holder  10 . This is accomplished by placing the cutter shank (not shown) in the collet  12  between the fingers  38 , as illustrated in FIGS. 4 a  and  4   b , which is sized to precisely fit the shank of the cutting tool. Then the collet  14 , as illustrated in FIGS. 2 a  and  2   b , while positioned within the second end  30  of the collet receiving portion  26  of the tool holder body  10 , is tightened by the draw bolt  16  placed through the first end  22  of the shank portion  20  of the tool holder  10  and threaded, as illustrated in FIGS. 3 a - 3   c , into the threaded aperture  32  of the collet  14 .  
         [0027]    Once the assembly is in place, the user employs wrenches placed on the flat areas  35  formed in the collet-receiving portion  26  of the body  12  and the head  17  of the draw bolt  16  to manipulate the draw bolt  16  into the collet  14  and the collet  14  into the body  12 . This action causes the fingers  38  of the collet  14  to close around the cutter shank (not shown) by the action of the collet fingers  38  which are preferably tapered on the diameter and free to react to the taper bore of the body  12  by the axial slots  40  which allow radial movement of the fingers  38 . Furthermore, the end of the collet  14  includes a raised portion  48  which fits precisely into the aperture  18  of the body  12  and further guides the collet  14  straight, maintaining concentricity between the collet  14  and the body  12 .  
         [0028]    Upon completion of tightening the cutter, the extended tool holder  10  is now placed into the machine tool holder (not shown). The flat areas  34  formed on the shank portion  20  of the extended tool holder  10  allow the user to further secure and orient the extended tool holder  10  in the machine tool holder.  
         [0029]    In sum, the present invention is an extended tool holder  10  comprising a body  12  having a shank for fit in a collet or larger tool holder, flats  34  for gripping with a wrench while tightening, at least one flat  35  formed on the body  12  for locking in place and orienting in another tool holder, a tapered body  12  on the outside diameter for reducing the diameter at the end, and a tapered internal diameter aperture  18  used for closing a collet  14  when pulled into the tapered aperture  18 . It has an aperture  18  through the center that incorporates various diameters that provide a shoulder  50  to inhibit the extent of the draw bolt head  16 , a guide for the fit of the guide portion of the collet  14 . The counter bore in the first end  22  of the shank portion  20  is constructed so that the head  17  of the draw bolt  16  extends outside the body  12  for ease of removal of the cutting tool by allowing the operator to tap the draw bolt  16  forward thereby pushing the collet  14  forward.  
         [0030]    The extended tool holder  10  further comprises a collet  14  which fits into the body  12  and is tapered with fingers  38  to close around the shank of the cutting tool when the collet  14  is pulled into the body  12 . The collet  14  also features a guide diameter on the end opposite the tapered end and aligns the collet  14  in the holder body  12  in a precision manner. The guide end of the collet  14  has an internally threaded aperture  32  that are employed to engage the draw bolt  16 . Furthermore, the collet  14  has a relief portion  46  that ensures contact between the guide section and the taper section with those details in the tool holder body  10 .  
         [0031]    In addition, the extended tool holder  10  comprises a draw bolt  16  that is used to pull in the collet  14  through the body  12  of the tool holder  10  whereby a) a cutting tool is placed into the collet  14  and is tightened by using wrenches on the body flats  34  and the draw bolt  16  which, b) pulls the collet  14  deeper into the holder body  12  and reacts against the internal tapered aperture  18  causing the fingers  38  of the collet  14  to close. Having secured the cutting tool into the extended tool holder  10 , the assembly is placed into another tool holder. The effect of having this mechanism is to allow a precision and ridged manner to hold small tools and, by the extended fashion of the tool holder  10 , allows the user to have access to places that are normally difficult to reach.  
         [0032]    The foregoing exemplary descriptions and the illustrative preferred embodiments of the present invention have been explained in the drawings and described in detail, with varying modifications and alternative embodiments being taught. While the invention has been so shown, described and illustrated, it should be understood by those skilled in the art that equivalent changes in form and detail may be made therein without departing from the true spirit and scope of the invention, and that the scope of the present invention is to be limited only to the claims except as precluded by the prior art. Moreover, the invention as disclosed herein, may be suitably practiced in the absence of the specific elements which are disclosed herein.