| 摘要 |
<p>Threads are provided for a fastener of a type having an opening in one member with internal helically-shaped threads comprising a plurality of convolutions about the inner periphery thereof, the threads having a crest and a root portion, the threads being formed about a longitudinal axis, and another member having helical threads comprising a plurality of convolutions about the outer periphery thereof, the threads having a crest and a root portion, the threads being formed about a longitudinal axis. The cylindrical portion is adapted to be placed in the opening by relative rotation of the two threaded members. The internal threads of the opening and the external threads of the cylindrical portion are substantially identical except that one of the thread formations has a first helix angle which, in an unstressed condition, is substantially constant throughout at least one thread convolution and that the other of the thread formations has a helix angle which, in an unstressed condition, is substantially constant throughout at least one thread convolution but which differs from the first helix angle by a magnitude of 39 to 85 percent of the first helix angle. As used herein, the helix angle is defined as the angle between a straight line projecting substantially along a portion of the crest of a respective thread formation and a plane which is perpendicular to the longitudinal axis. This thereby causes a higher prevailing torque for the purpose of impeding relative movement of the threaded members when the threads are engaged. This invention is therefore particularly useful for the construction of what is commonly referred to as lock nuts by a simple procedure using equipment which can mass produce the tap.</p> |
