This invention relates to a self-locking nut of the anti-reversing type, to a method for fabricating such a self-locking nut, and to such method including the new use of a material suitable for the anti-reversing pin component of the self-locking nut.
This invention is further concerned with self-locking nuts of a type which are suitable for use in the fabrication of structures such as microwave towers and highway structures. In the fabrication of such structures it is desirable to use nuts and bolts which have a very effective protective coating to minimize deterioration due to rust, corrosion, etc.
A very effective protective coating for steel nuts and bolts is referred to as "hot dip galvanized"; and one characteristic of this protective coating is that the thickness of the coating is not uniform. With that characteristic, many known types of lock nuts may not be used effectively, since where the hot dip coating is particularly thick, the binding may be so severe that the self-locking nut may not be turned.
A form of self-lacking nut which has been found effective for use with bolts treated by the hot dip galvanized process, is a nut having an anti-reversing pin which projects generally radially inward from the nut for interference engagement with the threads of the bolt. In the manufacture of such anti-reversing nut, the interference pin projects radially into the thread bore; and in use that pin will be deflected in one direction or the other, about 30.degree. from the radial position for example, to assume an anti-reversing position relative to the direction in which the nut is being turned on the bolt. The tip of this pin is configured to be received partially within the groove of the bolt thread and to bite into the bolt material when urged in a reverse direction. The pin, which is anchored in the nut, is necessarily elastic to maintain the interference engagement with the bolt thread and maintain the anti-reversing force, which enables it to perform its function as a self-locking nut.
When it is desired to remove the nut from the bolt, a high torque must be applied which effects the swinging of the anti-reversing pin and accompanying deflection in the opposite direction from the radial position, whereby the nut then becomes anti-reversing in the opposite direction.
To provide an effective self-locking nut for a hot dip galvanized bolt, it is desirable that the nut be relatively free spinning, either while threading the nut onto the bolt or while unthreading the nut from the bolt, after overcoming the high anti-reversing torque, for several reasons. One reason is to minimize any galling or other defacing of the protective coating on the threads which may result in exposure of the base metal and thereby subject the bolt to rust or other corrosion. Another reason is to facilitate the construction of structures being asembled with nuts and bolts and to promote the safety of the workers who may be laboring at either high or otherwise hazardous locations. When working at high locations, such as on microwave towers, the use of power tools is sometimes impractical; and a requirement for applying high torque to these fasteners may be hazardous to the workers who must at all times be concerned with body balance and stability.
While self-locking nuts having inwardly directed interference pins as above described are known in the art, a problem with some of these nuts is that the pins break off after being deflected because of lack of sufficient elasticity. Those nuts of course must be discarded; and the reliability of the nuts comes into question. That is, do the anti-reversing pins have sufficient elasticity to perform the intended anti-reversing or locking function.
An object of this invention is to provide an improved self-locking nut of the anti-reversing type, and a method for manufacturing same.
Another object of this invention is to provide an improved self-locking nut of the anti-reversing type which is relatively free spinning while running the nut onto or off from a bolt, and a method for manufacturing same.
A further object of this invention is to provide a self-locking nut of the anti-reversing type which is adapted to be used repeatedly, and a method for manufacturing same.
Still another object of this invention is to provide an improved self-locking nut of the anti-reversing type having an anti-reversing pin which projects into interference engagement with the bolt and which is adapted to be oscillated between alternative anti-reversing positions, and a method for manufacturing same.
A still fruther object of this invention is to provide a self-locking nut of the anti-reversing type as set forth in the preceding object, wherein the anti-rotation pin is fabricated from quarter hard stainless steel welding rod.
Another object of this invention is to provide an improved self-locking nut of the anti-reversing type having an anti-reversing pin which projects into interference engagement with the bolt, and which has the required elasticity for repeated oscillations between alternative anti-reversing positions, and a method for manufacturing same.
The novel features and the advantages of the invention, as well as additional objects thereof, will be understood more fully from the following description when read in connection with the accompanying drawings.