Threaded Insert for Use with Archery Arrows and Crossbow Bolts

Abstract

Inserts for coupling a broadhead and an arrow shaft or a crossbow bolt, wherein an internal thread pattern in the tube is different from an external thread pattern at an end of the broadhead.

What is claimed is: 
     
         1 . An insert for coupling a broadhead and an arrow shaft, the insert comprising a tube comprising a threaded portion having an internal thread pattern configured for threadably engaging a threaded end of a broadhead, wherein
 the internal thread pattern of the tube is different from an external thread pattern on the threaded end of the broadhead; and   at least a portion of the tube is disposed within an opening at an end of the arrow shaft.   
     
     
         2 . The insert of  claim 1 , wherein the internal thread pattern comprises:
 a first thread flank disposed in a first direction at a first angle relative to a line parallel to an axial centerline of the insert; and   a second thread flank disposed in a second direction at a second angle relative to the line parallel to the axial centerline of the insert, the second thread flank comprising a wedge ramp disposed in a third direction at a third angle relative to the line parallel to the axial centerline of the insert.   
     
     
         3 . The insert of  claim 2 , wherein
 the first and the second angles are substantially equal; and   the third angle is different from the substantially equal first and the second angles.   
     
     
         4 . The insert of  claim 3 , wherein
 the first and the second angles each are approximately 60 degrees; and   the third angle is approximately 30 degrees.   
     
     
         5 . The insert of  claim 3 , wherein the external thread pattern comprises a pair of thread flanks each disposed at an angle substantially equal to the substantially equal first and the second angles 
     
     
         6 . The insert of  claim 2 , wherein
 an angle between the first thread flank and the wedge ramp is approximately 90 degrees; and   an angle between the second thread flank and the wedge ramp is approximately 30 degrees.   
     
     
         7 . The insert of  claim 2 , wherein the first thread flank and the wedge ramp intersect at a thread root on an internal surface of the tube. 
     
     
         8 . The insert of  claim 7 , wherein the second thread flank and the wedge ramp intersect at a location opposite the thread root. 
     
     
         9 . The insert of  claim 2 , wherein the first and the second thread flanks are adapted to receive a thread of the external thread pattern. 
     
     
         10 . The insert of  claim 9 , wherein the first and the second thread flanks and the external thread pattern have complementary profiles. 
     
     
         11 . The insert of  claim 9 , wherein the external thread pattern comprises at least one thread flank, wherein at least a portion of a surface of the at least one thread flank contacts at least a portion of a surface of the wedge ramp. 
     
     
         12 . The insert of  claim 2 , wherein the insert comprises:
 a plurality of the first thread flanks;   a plurality of the second thread flanks; and   a plurality of wedge ramps.   
     
     
         13 . The insert of  claim 1 , wherein the internal thread pattern comprises a unidirectional threadform. 
     
     
         14 . The insert of  claim 13 , wherein the unidirectional threadform is configured to engage with a conventional threadform. 
     
     
         15 . The insert of  claim 14 , wherein
 the unidirectional threadform comprises a plurality of wedge ramps; and   the conventional threadform comprises a plurality of crests;   wherein, the plurality of the wedge ramps and the plurality of the crests are wedged together with a relatively large force.   
     
     
         16 . The insert of  claim 15 , wherein radial clearances between the plurality of wedge ramps and the plurality of crests is substantially reduced. 
     
     
         17 . The insert of  claim 15 , comprising a substantially continuous contact between the internal thread pattern and the external thread pattern. 
     
     
         18 . The insert of  claim 14 , wherein a threaded engagement between the unidirectional threadform and the conventional threadform substantially reduces lateral movement between the internal and the external thread patterns.