Abstract:
A fastener extractor and a method of extracting a fastener are provided. The fastener extractor includes a shaft, an engagement end at a distal end of the shaft and an attachment end at a proximal end of the shaft. The engagement end includes a plurality of helical ridges and grooves. The attachment end extends axially from the shaft and includes a hexagonal cross-sectional portion adapted to engage an extraction tool. Adjacent ones of the plurality of the grooves form the ridges therebetween and the plurality of ridges is adapted to engage a pre-formed opening in a fastener to be removed.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to tools for turning threaded fasteners such as screws, bolts, nuts, studs, and the like, and more particularly relates to the use of an extractor tool for removing threaded fasteners having heads that have been broken off or otherwise damaged.  
       BACKGROUND OF THE INVENTION  
       [0002]     It is well known to use extraction tools to remove threaded fasteners that have been damaged. Typically, these tools are either used in conjunction with a socket wrench, or else a wrench may be placed around the periphery of a squared end of the extraction tool in order to apply torque to remove the damaged fastener. These tools typically have “teeth” made up of angled faces to engage an opening in the damaged fastener. Extraction tools having scraping edges instead of teeth have also been used to remove fasteners, using a drill to drive the extraction bit into the end of the fastener and then reversing the drill to remove the fastener.  
         [0003]     Extraction tools having teeth to engage the damaged fastener typically are designed to be attached to a wrench on one end, and to engage the fastener at the other end. These extraction tools are usually designed for placement in a pre-drilled hole within the end of the damaged fastener and then using the wrench or other tool, including a drill, to remove the fastener. Exchanging tools in the wrench or other tool can be cumbersome and time-consuming.  
         [0004]     Accordingly, it would be desirable to have a fastener extractor that can be quickly inserted and removed from an extraction tool using a quick-release attachment end which overcomes one or more of the disadvantages of using a standard square end on a fastener extractor.  
       BRIEF SUMMARY OF THE INVENTION  
       [0005]     To alleviate the disadvantages of the prior art, a fastener extractor is provided herein. The fastener extractor includes a shaft, an engagement end at a distal end of the shaft and an attachment end at a proximal end of the shaft. The engagement end includes a plurality of helical ridges and grooves. The attachment end extends axially from the shaft and includes a hexagonal cross-sectional portion adapted to engage an extraction tool. Adjacent ones of the plurality of the grooves form the ridges therebetween and the plurality of ridges is adapted to engage a pre-formed opening in a fastener to be removed.  
         [0006]     In another embodiment of the present invention, a kit for extracting fasteners is provided. The kit includes a plurality of fastener extractors. Each of the plurality of extractors includes a shaft, an engagement end at a distal end of the shaft and an attachment end at a proximal end of the shaft. The engagement end includes a plurality of helical ridges and grooves. The attachment end extends axially from the shaft and includes a hexagonal cross-sectional portion adapted to engage an extraction tool. Adjacent ones of the plurality of the grooves form the ridges therebetween and the plurality of ridges is adapted to engage a pre-formed opening in a fastener to be removed.  
         [0007]     In another embodiment of the present invention, a method is provided for removing a fastener. The method includes drilling an opening into the head of a fastener and providing a fastener extractor including a shaft, an engagement end at a distal end of the shaft and an attachment end at a proximal end of the shaft. The engagement end includes a plurality of helical ridges and grooves. The attachment end extends axially from the shaft and includes a hexagonal cross-sectional portion adapted to engage an extraction tool. The method further includes engaging at least a portion of the engagement end of the fastener extractor with the opening in the fastener and rotating the fastener extractor. Rotation of the fastener extractor relatve to the fastener causes the ridges of the fastener extractor to engage the fastener to loosen the fastener.  
         [0008]     The invention provides a fastener extractor that is configured for engagement of a fastener to be extracted and allows for the convenient removal of damaged fasteners. The fastener extractor may be utilized with generally available tools to impart a large gripping and disengaging torque. The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS  
       [0009]      FIG. 1  is a perspective view of an embodiment of the present invention;  
         [0010]      FIG. 2  is a front plan view of the embodiment of  FIG. 1 ;  
         [0011]      FIG. 3  is a perspective view of an alternative embodiment of  FIG. 1 ;  
         [0012]      FIG. 4  is a front plan view of the alternate embodiment of  FIG. 3 ;  
         [0013]      FIG. 5  is a perspective view of an alternative embodiment of  FIG. 1 ; and  
         [0014]      FIG. 6  is a schematic view of a kit. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]     An embodiment of a fastener extractor  2  for removing threaded fasteners that have been damaged is shown in  FIG. 1 . The fastener extractor preferably is made of 4150 hardened steel, although in alternate embodiments other hardenable steels may be used that have a hardness in the range approximately 50 to 60 Rockwell C. In additional embodiments, moreover, powdered metals and other hardenable materials may also be used to make the fastener extractor.  
         [0016]     The fastener extractor  2  includes a shaft  12  having a tool attachment end  4  at a proximal end  6  and a fastener engagement end  8  at a distal end  10  of the shaft  12  of the fastener extractor  2 . A portion of the elongate shaft  12  connects the tool attachment end  4  to the fastener engagement end  8 . Referring also to  FIG. 2 , in a preferred embodiment the attachment end  4  includes a hexagonally shaped outer surface  14 . The hexagonal portion  14  of the attachment end  4  may be used to facilitate the use of a quick-release chuck to attach the fastener extractor to an extraction tool  15  or to attach the attachment end  4  to a hex bit. The attachment end  4  may further include an arcuate groove  16  circumferentially surrounding the attachment end  4 . The arcuate groove  16  is adapted to receive one or more detents (not shown), such as the detent balls in a quick-release locking mechanism in a tool chuck. The detents engage the arcuate groove  16  of the attachment end  4  to hold the fastener extractor  2  in the tool chuck. In an alternative embodiment, shown in  FIG. 3 , the attachment end  4  may include a hexagonally shaped outer surface  14  that extends from the attachment end  4  to the shaft  12 . In these types of embodiments, the extraction tool may be, by way of example, a t-handled tap wrench, a socket wrench, an open wrench or a power tool. The attachment end  4  may be of any size known to one of skill in the art in order to fit with the extraction tool  15 . The attachment end  4  may be any shape known to one skilled in the art including square or rounded and the like.  
         [0017]     The fastener engagement end  8  includes a plurality of helical ridges  20  and grooves  22  extending from the shaft  12  to the distal end  10  of the fastener extractor  2 . The ridges  20  curve radially and outwardly and preferably taper from the shaft  12  to the distal end  10  along a longitudinal axis  24  extending the length of the fastener extractor  2 . Preferably the ridges  20  and the grooves  22  may be equidistantly spaced apart and may each have a uniform size and shape. Alternatively, the ridges  20  and grooves  22  may be non-uniformly spaced apart and need not have a uniform size and shape. In a preferred embodiment of the present invention, the plurality of ridges  20  may be adapted to facilitate gripping of the fastener to be removed by the fastener extractor  2  without decreasing the strength of the outer surface  26  of the engagement end  6  and without removing material from the fastener itself. The ridges  20  may include angular ridges  28  as shown in  FIG. 1  or smooth, radiused surfaces  30  as shown in  FIG. 3  for engaging a hole formed in the fastener.  
         [0018]     Preferably the fastener extractor  2  includes a helical spiral engagement end  6  for removing a threaded fastener. The engagement end  6  may have a right-handed helical spiral or a left-handed helical spiral as viewed from the tip (as shown in  FIG. 4 ) to remove an oppositely threaded fastener. The ridges  20  are formed by adjacent grooves  22  and any number of alternating ridges  20  and grooves  22  may be used for the engagement end  6 . In the embodiments shown in  FIGS. 1 and 3 , the engagement end may include 3 to 8 ridges  20  and 3 to 8 grooves  22 , preferably 5 ridges  20  and 5 grooves  22 .  
         [0019]     As shown in an alternative embodiment in  FIG. 5 , the extractor  100  may include a larger number of ridges  120  and grooves  122 . When a greater number of ridges  120  and grooves  122  are used, the ridges  120  and grooves  122  may be smaller and narrower. For each of the embodiments described herein, the number of ridges  20 ,  120  and grooves  22 ,  122  will depend on the size of the fastener extractor  2 ,  100  and the size of the fastener to be extracted as will be understood by one of skill in the art. The fastener extractor  100  is similar to the extractor  2  described above, and includes a shaft  112  having a tool attachment end  104  at a proximal end  106  and a fastener engagement end  108  at a distal end  110  of the shaft  112 . A portion of the elongate shaft  112  connects the tool attachment end  104  to the fastener engagement end  108 . The shaft  112  may be cylindrical in shape and may have a greater diameter than the attachment end  104  and the engagement end  108 . The shaft  112  may be any shape and diameter known to one of skill in the art. The distal end  110  of the shaft  112  may be flat as shown in  FIG. 5 , however, any shape for the distal end  110  is acceptable, including circular, pointed and others. The extractor  110  may include a draft angle  124  tapering inwardly from the shaft  112  to the distal end  110 . The draft angle  124  may be measured from a distal end  126  of the shaft  112  to the distal end  110 . Preferably the draft angle  124  is about 2° to 8° inclusive, more preferably about 4° to 6° inclusive, most preferably about 4° inclusive.  
         [0020]     In this embodiment, the attachment end  104  includes a hexagonally shaped outer surface  114 . The hexagonal portion  114  of the attachment end  104  may be used to facilitate the use of a quick-release chuck to attach the fastener extractor to an extraction tool  15  or to attach the attachment end  104  to a hex bit. The attachment end  104  may further include an arcuate groove  116  circumferentially surrounding the attachment end  104 . The arcuate groove  116  is adapted to receive one or more detents (not shown), such as the detent balls in a quick-release locking mechanism in a tool chuck. The detents engage the arcuate groove  116  of the attachment end  104  to hold the fastener extractor  100  in the tool chuck. The attachment end  104  may be of any size known to one of skill in the art in order to fit with the extraction tool  15 . The attachment end  104  may be any shape known to one skilled in the art including square or rounded and the like.  
         [0021]     As will be readily appreciated, the fastener extractor  2 ,  100  may be machined to various sizes in order to be used with a wide range of fastener sizes. For example, the fastener extractor  2 ,  100  may be used to remove fasteners that include but are not limited to sizes including 3/32-inch to 2½ inches.  
         [0022]     Operation of the fastener extractor is as follows. The operation is described with reference to the fastener extractor  2  and the same operation applies to the fastener extractor  100 . A hole is drilled into the damaged end of the fastener using a separate drill bit sized and shaped to bore an appropriate hole in the fastener. The size of the drill bit used to make this pre-formed hole will depend on the size of the fastener to be removed and the size of the fastener extractor  2  used to remove the fastener. The hole need extend only partially into the head of the fastener, but should be of a diameter wide enough to accommodate at least the tip portion of the extractor. The fastener extractor  2  is then inserted into the pre-drilled hole deep enough so that the ridges  20  of the engagement end  6  engage the sides of the hole. The extraction tool  15  is attached to the attachment end  4  of the fastener extractor  2  either before or after insertion of the ridges  20  in the hole of the fastener to facilitate rotation of the extractor  2 . Rotation of the fastener extractor  2  relative to the fastener during loosening will cause the ridges  20  to bite into the fastener pushing the extractor  2  firmly into the hole during rotation to facilitate the extractor  2  biting into the fastener. Further rotation will cause the fastener extractor to be seated more firmly in the hole in the fastener due to the increasing diameter of the engagement end  6  towards the shank  12 . Thus, rotation of the fastener extractor  2  continues until the fastener is removed from the substrate.  
         [0023]     In another embodiment of the present invention, a kit  50  comprising a plurality of fastener extractors  2  is provided. As shown in  FIG. 5 , the kit  50  may include a plurality of sizes for the engagement end  6  of the extractor  2  and housed together in a set of such sizes. For example, in a preferred embodiment, the plurality of extractors may include extractors  2  having attachment ends  6  that range in size for removal of fasteners ranging in size from about 3/32-inch to 2½ inches. Other sizes for the receiving end  6  of the extractor  2 , including metric units, are also possible. The kit  50  preferably includes 3 to 13 of the extractors  2 , and more preferably, 5 to 9 of the extractors  2  adapted to engage the extraction tool  15 , although the kit need not be so limited. The kit  50  may also include fastener extractors having different configurations for the engagement end as well as different configurations for the attachment end.  
         [0024]     The kit  50  may further include the extraction tool  15 . The extraction tool  15  may be adapted to drive the extractor  2  to remove threaded fasteners. The extraction tool  15  may be adapted to drive the extractor  2  by attaching to a generally hexagonal attachment end  4 . In a preferred embodiment, the extraction tool  15  may be a t-handled tap wrench or a quick release chuck attached to a hand or power tool to drive the extractor  2 . However, one of skill in the art will recognize that any extraction tool  15  may be used that will fit with the attachment end  4  of the fastener extractor  2 .  
         [0025]     Additionally, the kit  50  may include a container  54  adapted to house the plurality of extractors  2  therein. As will be readily understood by those skilled in the art, the container  54  may be any type of container adapted to house the plurality of extractors  2  and may also include the extraction tool  15 . In a preferred embodiment, the container may be formed from molded plastic, include a re-closeable lid and include a plurality of recesses within the container adapted to receive each of the plurality of extractors  2  of the kit  50 . The container may be used to display and sell the plurality of extractors  2  and to store the plurality of extractors after the kit  50  is sold. Alternatively, the container  54  may be a disposable container adapted to temporarily house the kit  50  for display for sale. Moreover, the kit may be made from materials other than plastic, such as, by way of example, acrylics or metal.  
         [0026]     While the embodiments of the invention disclosed herein are presently considered to be preferred, various changes and modifications can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.