GB2101252A - Locknut - Google Patents

Abstract

A locknut has an internal thread the lower portion of which is of uniform diameter about an axis (16) inclined at a small angle alpha to the axis (14) of the body of the nut. The upper portion of the thread is formed on a frusto-conical surface beta about the axis (16) and the thread is distorted inwardly at its upper end (at 20). When the nut is threaded onto a bolt it is inclined at the angle alpha to the bolt shank. When its lowest corner 15 engages the surface of the component to be secured; the nut rocks until the whole of surface 11 contacts the other surface and the distorted thread portion 20 is wedged against the bolt threads to lock the nut. <IMAGE>

Description

SPECIFICATION Locknut This invention relates to locknuts.

There is a well known requirement in engineering for a nut that is simple and inexpensive, that may be screwed on or off simply and yet that when screwed on will remain in position and will not tend to loosen.

It is an object of the present invention to provide such a locknut.

The present invention is a locknut having a body defining an axis and having top and bottom surfaces substantially perpendicular to said axis, a tapped hole passing through the body from the bottom to the top surface, the bottom part of the hole being of uniform diameter about a second axis and the upper part of the hole tapering outwardly at a first angle about the second axis which is inclined at a second angle with respect to the body axis, the thread adjacent the top surface being distorted inwardly at at least one area of the periphery of the hole which is closer to the body axis than the second axis.

Preferably the thread is distorted at two areas symmetrically located with respect to the plane containing the first and second axes.

Preferably the outer periphery of the bottom surface is formed as a chamfer at the second angle to the plane of the bottom surface.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side elevation of a locknut according to the present invention being screwed onto a bolt; Fig. 2 is a plan view of the locknut of Fig. 1; and Fig. 3 is a sectional elevation of the locknut on the line Ill-Ill of Fig. 2.

As shown in the drawings, a locknut according to the present invention has a body 10 which externally is of the conventional hexagonal form and has a bottom surface 11 and a top surface 12 provided by a collar 1 3 integral with the main body portion. The body 10 defines an axis 14 perpendicular to the surfaces 11 and 12 and the periphery of the bottom surface 11 is chamfered to provide a surface 1 5 inclined at an angle a to the bottom surface.

The body 10, as seen best in Fig. 2, has a tapped hole passing between the bottom and top surfaces 11 and 12, the bottom portion of the hole, in this embodiment the bottom half, is of uniform diameter about an axis 1 6 whereas the rest of the hole, i.e. the top portion, is in the form of an expanding cone about the axis 1 6. The axis 1 6 is inclined at an angle a to the axis 14 of the body and which meets the axis 14 in the plane of the bottom surface 11. The included cone angle is 2P.

The collar 13 as seen in Fig. 3 has been distorted inwardly, after the thread has been formed in the nut, in two areas 20 and 21 symmetrically located on either side of the plane 22 containing the axes 14 and 1 6 and closer to the axis 14 than to the axis 1 6. This distortion of the collar produced a corresponding distortion of the internal thread in the areas 20 and 21 adjacent the top surface 12, the distorted thread being brought slightly closer to the axis 1 4 than the thread adjacent the bottom surface 11.

Reverting now to Fig. 1, the nut is being screwed onto a bolt 25 and is inclined at the angle a to the horizontal. In terms of Fig. 3 the thread on the bolt engages the thread in the nut at the bottom left and top right. The nut, in this attitude, moves down the bolt until the surface 1 5 at its lower corner engages the surface 30. Further tightening of the nut then causes it to rock on the surface 1 5 until the lower surface 11 engages the surface 30 at which time the distorted thread areas 20 and 21 are wedged onto the shank of the bolt and the nut is effectively locked.

It should be understood that, to illustrate the principles involved, the angles a and p have been greatly exaggerated in the drawings and that the actual angles involved, while dependent on the size of the nut, are in fact very small as can be seen by considering that the angle a assumed by the nut in Fig. 1 is permitted by the tolerances between the threads in the lower portion of the nut.

Modifications may be made to the embodiment described. For example, instead of two areas of distorted thread only one may be provided.

1. A locknut having a body defining an axis and having top and bottom surfaces substantially perpendicular to said axis, a tapped hole passing through the body from the bottom to the top surface, the bottom part of the hole being of uniform diameter about a second axis and the upper part of the hole tapering outwardly at a first angle about the second axis which is inclined at a second angle with respect to the body axis, the thread adjacent the top surface being distorted inwardly at at least one area of the periphery of the hole which is closer to the body axis than the second axis.

2. A locknut as claimed in claim 1, in which the thread is distorted at two areas symmetrically located with respect to the plane containing the first and second axes.

3. A locknut as claimed in claim 1 or claim 2, in which the outer periphery of the bottom surface is formed as a chamfer.

4. A locknut as claimed in claim 3, in which the chamfer lies at the second angle to the plane of the bottom surface.

5. A locknut substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Locknut This invention relates to locknuts. There is a well known requirement in engineering for a nut that is simple and inexpensive, that may be screwed on or off simply and yet that when screwed on will remain in position and will not tend to loosen. It is an object of the present invention to provide such a locknut. The present invention is a locknut having a body defining an axis and having top and bottom surfaces substantially perpendicular to said axis, a tapped hole passing through the body from the bottom to the top surface, the bottom part of the hole being of uniform diameter about a second axis and the upper part of the hole tapering outwardly at a first angle about the second axis which is inclined at a second angle with respect to the body axis, the thread adjacent the top surface being distorted inwardly at at least one area of the periphery of the hole which is closer to the body axis than the second axis. Preferably the thread is distorted at two areas symmetrically located with respect to the plane containing the first and second axes. Preferably the outer periphery of the bottom surface is formed as a chamfer at the second angle to the plane of the bottom surface. An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side elevation of a locknut according to the present invention being screwed onto a bolt; Fig. 2 is a plan view of the locknut of Fig. 1; and Fig. 3 is a sectional elevation of the locknut on the line Ill-Ill of Fig. 2. As shown in the drawings, a locknut according to the present invention has a body 10 which externally is of the conventional hexagonal form and has a bottom surface 11 and a top surface 12 provided by a collar 1 3 integral with the main body portion. The body 10 defines an axis 14 perpendicular to the surfaces 11 and 12 and the periphery of the bottom surface 11 is chamfered to provide a surface 1 5 inclined at an angle a to the bottom surface. The body 10, as seen best in Fig. 2, has a tapped hole passing between the bottom and top surfaces 11 and 12, the bottom portion of the hole, in this embodiment the bottom half, is of uniform diameter about an axis 1 6 whereas the rest of the hole, i.e. the top portion, is in the form of an expanding cone about the axis 1 6. The axis 1 6 is inclined at an angle a to the axis 14 of the body and which meets the axis 14 in the plane of the bottom surface 11. The included cone angle is 2P. The collar 13 as seen in Fig. 3 has been distorted inwardly, after the thread has been formed in the nut, in two areas 20 and 21 symmetrically located on either side of the plane 22 containing the axes 14 and 1 6 and closer to the axis 14 than to the axis 1 6. This distortion of the collar produced a corresponding distortion of the internal thread in the areas 20 and 21 adjacent the top surface 12, the distorted thread being brought slightly closer to the axis 1 4 than the thread adjacent the bottom surface 11. Reverting now to Fig. 1, the nut is being screwed onto a bolt 25 and is inclined at the angle a to the horizontal. In terms of Fig. 3 the thread on the bolt engages the thread in the nut at the bottom left and top right. The nut, in this attitude, moves down the bolt until the surface 1 5 at its lower corner engages the surface 30. Further tightening of the nut then causes it to rock on the surface 1 5 until the lower surface 11 engages the surface 30 at which time the distorted thread areas 20 and 21 are wedged onto the shank of the bolt and the nut is effectively locked. It should be understood that, to illustrate the principles involved, the angles a and p have been greatly exaggerated in the drawings and that the actual angles involved, while dependent on the size of the nut, are in fact very small as can be seen by considering that the angle a assumed by the nut in Fig. 1 is permitted by the tolerances between the threads in the lower portion of the nut. Modifications may be made to the embodiment described. For example, instead of two areas of distorted thread only one may be provided. CLAIMS

1. A locknut having a body defining an axis and having top and bottom surfaces substantially perpendicular to said axis, a tapped hole passing through the body from the bottom to the top surface, the bottom part of the hole being of uniform diameter about a second axis and the upper part of the hole tapering outwardly at a first angle about the second axis which is inclined at a second angle with respect to the body axis, the thread adjacent the top surface being distorted inwardly at at least one area of the periphery of the hole which is closer to the body axis than the second axis.

2. A locknut as claimed in claim 1, in which the thread is distorted at two areas symmetrically located with respect to the plane containing the first and second axes.

3. A locknut as claimed in claim 1 or claim 2, in which the outer periphery of the bottom surface is formed as a chamfer.

4. A locknut as claimed in claim 3, in which the chamfer lies at the second angle to the plane of the bottom surface.

5. A locknut substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.