GB2328484A

GB2328484A - Lock nut

Info

Publication number: GB2328484A
Application number: GB9817857A
Authority: GB
Inventors: Andreas Gutt
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-08-23
Filing date: 1998-08-18
Publication date: 1999-02-24
Also published as: GB9817857D0; GB9717859D0; DE19837940A1

Abstract

A lock nut assembly 1 comprises a nut 3 for engagement with a threaded member 2 and a locking ring 7 threaded onto an external diameter of the nut 3. When the ring 7 is tightened onto the nut 3, a conical face 20 on the ring 7 urges pins 6 inwardly into engagement with the threaded member 2 through apertures 5 in the nut 3. When the assembly 1 is attached to the threaded member 2, a flange 12 on the nut 3 is deformed into a groove 21 on the ring 7 to secure the ring 7 in position. Alternatively, in the embodiment of figure 3, the locking ring (7) may also be threaded onto the threaded member (2) and have an external screw thread (19) which locks to an internal thread (16) of the nut (3), the threads (16,19) being of coarser pitch than the threads (4,28) between the nut (3) and threaded member (2). The ring (7) and nut (3) are screwed onto the threaded member (2) together, but then on unscrewing the ring (7) from the nut (3), the flanks of the threads (16,19) lock.

Description

LOCK NUTS This invention relates to a lock nut assembly which is adapted to be locked onto a threaded member.

One well-known type of lock nut has one or more locking pins or balls disposed in holes in the nut, and urged against the threaded member by screws. When such a lock nut is to be secured onto a threaded member, the screws have to be tightened individually a number of times to ensure that the lock nut is perpendicular to the axis of the threaded member. However, the lock nut and the threaded member may then not be on the same centre line, which is important to ensure secure locking.

A further problem is that the screws can work loose in use, through vibration or the fast change of direction of rotation of the threaded member, thus allowing the pins to move, so that they no longer secure the nut on the threaded member.

According to the present invention, a lock nut assembly comprises a lock nut member adapted to be locked onto a threaded member, a locking ring adapted to be mounted rotatably on the lock nut member, rotation of the ring relative to the lock nut member operating locking means which lock the lock nut member to the threaded member, and means for securing the nut member against rotation relative to the locking ring.

The use of the locking ring ensures that the locking means cannot move in use, since they are operated by the locking ring, which is secured to the nut member. The assembly is also very quick and easy to assemble onto a threaded member, since the nut member is secured by operation of only one component, the locking ring, rather than two or more screws.

In one embodiment the locking means comprises at least two locking elements, each element being received in an aperture in the lock nut member with a head projecting outwardly, the locking ring engaging the heads to urge the locking elements inwardly simultaneously. This ensures that the nut member and threaded member are on the same centre line.

Preferably the locking ring has a threaded connection with the nut member. It is then easy to use. The nut member preferably has an external thread, with which an internal thread on the ring engages. The locking ring may have a conical surface engaging with a corresponding inclined surface on the heads of the locking elements. This ensures that the elements are urged inwardly gradually and simultaneously.

Each locking element preferably comprises a pin. The pins are preferably of brass, and are inserted in the apertures before an internal thread, for engagement with the threaded member, is formed on the nut member. The thread is then also formed on the pins, to assist their engagement with the threaded member. The apertures may extend radially through the nut member, but are preferably angled.

In another embodiment the locking ring has a first thread engaging the threaded member and a second thread of different pitch engaging a complementary thread on the nut member, the locking means comprising frictional contact between the threads arising on relative rotation of the lock nut member and the locking ring.

In use the locking ring and nut member are secured together and screwed onto the threaded member. The locking ring is then unscrewed, and locking takes place because of the difference in pitch of the first and second threads. This construction provides a high locking force, as the frictional contact acts in three places, that is, between the nut member and the threaded member, between the locking ring and the threaded member, and between the locking ring and the nut member. This embodiment has the advantage of a simpler construction, since the locking elements are omitted.

The second thread on the locking ring is preferably an external thread engaging an internal thread on the nut member. The pitch of the second thread is preferably greater than that of the first thread. The nut member conveniently has a shoulder with which the locking ring engages to define the fully assembled position. The first thread is cut with the nut member and locking ring in the fully assembled position.

The means securing the nut member and locking ring against relative rotation preferably comprises a shoulder on one component, deformed into a groove on the other component. The deformation may be reversed, to allow the locking ring, and hence the nut member, to be removed if necessary. Preferably the groove extends axially. It may be provided in the locking ring, and the shoulder provided on the nut member. There may be more than one groove, to enable the assembly to be re-used.

Some embodiments of the invention are illustrated by way of example, in the accompanying drawings, in which: Figure 1 is a cross-section through a lock nut assembly in its position of use; Figure 2 is a plan view of a locking ring of Figure 1; Figure 3 shows a cross-section through a modification of the embodiment shown in Figures 1 and 2; and Figure 4 is a plan view of the embodiment shown in Figure 3.

The lock nut assembly shown in Figure 1 is adapted to be locked onto a threaded member 2 (shown in chain-dotted outline) with an axis A.

The assembly 1 comprises a lock nut member 3 having an internal screw thread 4 engaging the threaded member 2 and four apertures 5 receiving locking elements in the form of pins 6, forming locking means adapted to be urged into engagement with the threaded member 2 by a rotatable locking ring 7. Securing means 8 secure the nut member 3 against rotation relative to the locking ring 7 in use.

The lock nut member 3 is of steel, and of annular outline. It has a stepped outer surface 9, so that it has a substantially L-shaped crosssection, and defines an annular recess 10 for receiving the locking ring 7.

The outer surface 9 is provided with circumferentially spaced sockets 11, which can receive tools enabling the lock nut member 3 to be rotated on the threaded member 2. Six sockets 11 are shown, but more could be provided. The outer periphery also has a flange 12 extending axially over the recess 10. The flange 12 forms a shoulder engaging over the locking ring 7, and comprises part of the securing means 8, as explained in more detail below. The recess 10 has a radially-extending wall 13, and a step 14 joining it to an axially-extending portion 15, the end of which is provided with an external screw thread 16. The apertures 5 are circumferentially spaced round the lock nut member 3, and extend from the junction of the step 14 and axially-extending portion 15 through to the internal thread 4. Each aperture 5 is inclined to a radius, and to the axis.

The locking pins 6 are of brass. Each has a head 17 projecting outwardly from the portion 15. Each head 17 is inclined to the axis. The inner end of each pin 6 has a screw thread 18 corresponding to the internal screw thread 4. The pins 6 are inserted in the apertures 5 before the screw thread 4 is formed, to ensure that the screw threads 4, 18 correspond.

The locking ring 7 is also an annular steel member. Its internal surface has a screw thread 19 corresponding to the external thread 16 on the lock nut member 3, and a conical face 20, whose inclination corresponds to that of the pin heads 17. As the ring 7 is screwed onto the nut member 3, the face 20 engages the heads 17, and urges them inwardly as it moves axially. The outer surface of the ring 7 has circumferentially spaced grooves 21 extending axially. Four grooves 21 are shown, but more may be provided. These grooves 21 also form part of the securing means 8, in that deformation of a part of the flange 12 into a groove 21 (as shown in the lower part of Figure 1) secures the locking ring 7 and nut member 3 against relative rotation.

The lock nut member 3 with the pins 6, and the locking ring 7 are formed as two separate components, which are assembled by screwing the locking ring 7 onto the axially-extending portion 15, but not so far as to cause the pins 6 to be urged inwardly.

For use, the assembly 1 is threaded onto the threaded member 2, and put in position, for example against a bearing (not shown) which it is to secure on the member 2. The lock nut member 3 is rotated by tools engaging in the sockets 11. When the lock nut member 3 is in position, the locking ring 7 is screwed further onto the lock nut member 3, so that the conical face 20 urges the pins 6 inwardly into engagement with the threaded member 2, to lock the nut member 3 in position. It will be appreciated that the pins 6 are urged inwardly simultaneously by the locking ring 7, ensuring that the threaded member 2 and the lock nut member 3 are co-axial, that is, they remain on a common centre line.

This arrangement also ensures that the lock nut member 3 is perpendicular to the axis.

Lastly, a portion of the flange 12 aligned with a groove 21 is deformed into the groove 21, to secure the lock nut member 3 and locking ring 7 against relative rotation. This ensures that the pins 6 cannot work loose, and come out of engagement with the threaded member 2, to unlock the assembly.

However, it is easy for the assembly 1 to be removed if required, simply by bending the flange portion out of the groove 21, and reversing the other assembly steps. The assembly 1 can be re-used if desired, by using different grooves 21 as part of the securing means 8.

It will be appreciated that the assembly 1 is easy to install, particularly as only one component, the locking ring 7, needs tightening to lock the pins 6.

In a modification (not shown), the securing means 8 is altered, in that the grooves 21 are formed on the lock nut member 3, and the flange 12 on the locking ring 7.

The embodiment shown in Figures 3 and 4 is a modification of the embodiment of Figures 1 and 2, and corresponding reference numerals have been applied to corresponding parts.

In Figures 3 and 4 the locking means is modified, being provided not by the pins 6 but by frictional contact of threads on the threaded member 2, the lock nut member 3 and the locking ring 7.

Thus, the locking pins 6 are omitted, as are the apertures 5 and the axially-extending portion 15 of the lock nut member 3. This reduces the axial length of the internal thread 4 engaging the threaded member 2. The thread 16 on the lock nut member 3 engaging the thread 19 on the locking ring 7 is provided as an internal thread on a wall of the recess 10. The recess 10 has an inner radial wall 25 and an outer radial wall 26. The sockets 11 are replaced by grooves 27.

The locking ring 7 is substantially L-shaped in cross-section, and is received in the recess 10. The ring 7 has an internal thread 28 of the same pitch as the thread 4, adapted to engage the threaded member 2. The thread 19 adapted to engage the thread 16 on the nut member 3 is an external thread. The threads 16, 19 have a coarser pitch than the threads 4, 28. At its inner end the locking ring 7 is adapted to engage the inner radial wall 25 on the nut member 3 to define a fully-assembled position of the assembly 1. At its outer end the locking ring 7 has an outwardly flanged portion 29 having the grooves 21.

The nut member 3 and locking ring 7 are assembled before the threads 4, 28 are made. The two parts 3, 7 are screwed together into their fully-assembled position in which the inner end of the locking ring engages the radial wall 25. The threads 4, 28 are then formed in one operation as a substantially continuous thread. This ensures that the two parts 3, 7 are coaxial.

In use, the assembly 1 in its fully-assembled position is threaded onto the threaded member 2 by using a tool engaging the grooves 27.

Locking is achieved by rotating the locking ring 7 in a direction to withdraw the ring 7 from the nut member 3. A tool is inserted in the grooves 21 to perform the rotation. The locking ring 7 has a limited amount of axial movement because of the difference in pitch of the threads 19 and 28. The flanks of the threads 4 and 28 come into frictional contact with those of the threaded member 2, while the flanks of the threads 16, 19 also come into frictional engagement, and thus provide the clamping locking force.

The clamping load is concentrated in three regions: between the internal thread 4 and the threaded member, between the internal thread 28 and the threaded member, and between the threads 16, 19. A large proportion of the clamping load is concentrated in the two or three end threads of these regions. Having three clamping areas produces a high locking force to secure the assembly 1 in position.

As the last step in assembly a portion of the flange 12 is deformed into a groove 21 to secure the lock nut member 3 and locking ring 7 against relative rotation. As in the embodiment of Figures 1 and 2, the assembly steps can be reversed and the assembly 1 re-used.

This embodiment has the advantage of requiring fewer components, and of producing higher locking forces.

Claims

1. A lock nut assembly comprising a lock nut member adapted to be locked onto a threaded member, a locking ring adapted to be mounted rotatably on the lock nut member, rotation of the ring relative to the lock nut member operating locking means which lock the lock nut member to the threaded member, and means for securing the nut member against rotation relative to the locking ring.

2. A lock nut assembly as claimed in claim 1, in which the locking means comprises at least two locking elements, each element being received in an aperture in the lock nut member with a head projecting outwardly, the locking ring engaging the heads to urge the locking elements inwardly simultaneously.

3. A lock nut assembly as claimed in claim 1 or claim 2, in which the locking ring has a threaded connection with the nut member.

4. A lock nut assembly as claimed in claim 3, in which the nut member has an external thread, with which an internal thread on the locking ring engages.

5. A lock nut assembly as claimed in any of claims 2 to 4, in which the locking ring has a conical surface engaging a corresponding inclined surface on the heads of the locking elements.

6. A lock nut assembly as claimed in any of claims 2 to 5, in which each locking element comprises a pin.

7. A lock nut assembly as claimed in claim 6, in which each pin is inserted in its aperture before an internal thread is formed on the nut member.

8. A lock nut assembly as claimed in any of claims 2 to 7, in which each aperture is angled relative to a radius of the assembly.

9. A lock nut assembly as claimed in claim 1, in which the locking ring has a first thread engaging the threaded member and a second thread of different pitch engaging a complementary thread on the nut member, the locking means comprising frictional contact between the threads arising on relative rotation of the lock nut member and the locking ring.

10. A lock nut assembly as claimed in claim 9, in which the second thread on the locking ring is an external thread engaging an internal thread on the nut member.

11. A lock nut assembly as claimed in claim 9 or claim 10, in which the pitch of the second thread is greater or less than that of the first thread.

12. A lock nut assembly as claimed in any of claims 9 to 11, in which the nut member has a shoulder with which the locking ring engages to define a fully assembled position.

13. A lock nut assembly as claimed in claim 12, in which the first thread is cut with the nut member and locking ring in the fully assembled position.

14. A lock nut assembly as claimed in any preceding claim, in which the means securing the nut member and the locking ring against relative rotation comprises a shoulder on one component deformed into a groove on the other component.

15. A lock nut assembly as claimed in claim 14, in which the groove extends axially.

16. A lock nut assembly as claimed in claim 14 or claim 15, in which the groove is provided in the locking ring and the shoulder is provided on the nut member.

17. A lock nut assembly as claimed in any of claims 14 to 16, in which more than one groove is provided.

18. A lock nut assembly substantially as described herein with reference to and as illustrated in Figures 1 and 2 of the accompanying drawings.

19. A lock nut assembly substantially as described herein with reference to and as illustrated in Figures 3 and 4 of the accompanying drawings.