GB2136077A

GB2136077A - Nut and bolt locking arrangement

Info

Publication number: GB2136077A
Application number: GB08306520A
Authority: GB
Inventors: Bengt O Frieberg
Original assignee: Nord Lock AB
Current assignee: Nord Lock AB
Priority date: 1983-03-09
Filing date: 1983-03-09
Publication date: 1984-09-12
Also published as: GB8306520D0

Abstract

A lock washer 10a has a gripping face 22 on one side and wedge faces 20a, 20b on the other side which cooperate with similar wedge faces on another part of the arrangement, e.g. a nut or a bolt head (Figs. 7 and 8) or a similar washer as shown, the cooperating parts being fixed together by adhesive 25, the fixing together being overcome when the assembly is tightened so as to permit relative rotation in tightening up the arrangement. <IMAGE>

Description

SPECIFICATION Lock nut and bolt locking arrangement This invention relates to a nut and bolt locking arrangement comprising a first lock washer which has on one side a gripping face and on its other side several wedge faces extending in the circumferential direction with intermediate end faces and a part to be locked in the firm of a like second washer a bolt or a nut, which on its side facing the first locking washer is provided with similar wedge faces which are inclined correspondingly to the wedge faces of the first lock washer and abut them.

In known nut and bolt locking arrangements of the above described kind (US-PS 3 263 727 or 4 1 34 438), the lock washer is formed in such a position relative to the part to be locked that the wedge faces provided on the lock washer are opposite the wedge faces on the part to be locked.

The wedge faces, of which the angle of inclination must always be somewhat greater than the angle of the thread of the nut or bolt to be locked, carry out their function only when the wedge faces of the lock washer about the wedge faces of the part to be locked. This means that for installing the known bolt and nut locking arrangements careful personnel have to be used, who must always watch that the locking washer is put on the right way round, which, unfortunately, is not always the case. If the locking washer is assembled incorrectly, the entire nut and bolt locking assembly is useless. Since the nut and bolt locking arrangement can be realised in different forms, the designation "part to be locked" is used generically in the different embodiments described in the following.A first embodiment consists in that the part to be locked is a second lock washer which is identical with the first but so arranged that its wedge faces face the wedge faces of the first lock washer. The two lock-washers are then arranged between an ordinary nut or an ordinary bolt head and a fixed machine part, so that the gripping face of the first locking washer faces the machine part and the gripping face of the second lock washer faces the nut or the bolt head. In another embodiment the part to be locked is a nut or a bolt head on which wedge faces and end faces are arranged which correspond with the wedge faces and end faces of the lock washer. In this embodiment the second lock washer is, so to speak, integrated in the nut or bolt head.

The invention is based on the problem of providing a nut and bolt locking arrangement of the kind described above, in which the insertion of the first lock washer is facilitated without it having to be assembled in its correct position with regard to the part to be locked, but in which nevertheless the locking effect is ensured.

This is achieved according to the invention in that the first lock washer is fixed to the part to be locked as by adhesive, which is released on tightening the arrangement and allows opposite rotation of the washer and the part to be locked.

The invention therefore starts with the idea of fixing the first lock washer to the part to be locked, namely an identical second lock washer or a nut or bolt head provided with wedge faces, in the factory, so that the first lock washer and the part to be locked form a unit up until insertion. By the factory fixing of the first lock washer to the part to be locked it is ensured that the first lock washer is always presented to the part to be locked in the correct position and that it also remains so until insertion. The insertion of this novel locking nut and bolt arrangement is also facilitated in that the first lock washer does not need to be checked to see that it is in the correct position. Since moreover the first lock washer is fixed to the part to be locked, the two parts can be inserted as a unit, which simplifies the insertion.By correctly positioning the first lock washer, the locking effect of the nut and bolt arrangement is always ensured.

It must be ensured by a suitable choice of adhesive that the temporary adhesion between the first lock washer and the part to be locked can be broken by tightening the arrangement. The part to be locked can, thus, be turned, after insertion, freely with regard to the first lock washer. It is therefore important for the correct operation of this kind of nut and bolt arrangement that the part to be locked can be turned with regard to the first - lock washer with minimal resistance from surface friction, adhesion etc. Thus if the opposed wedge faces of the first lock washer and the part to be locked cannot be relatively rotated, then the first lock washer would turn with the part to be locked and the tightening between the threads of the bolt and nut effected by the wedge faces would not occur.

An advantageous form of the invention consists in that the opposed end faces are arranged with a spacing from each other. The first lock washer is therefore so fixed to the part to be locked that a space is left between the end faces of the first lock washer and the end faces of the part to be locked.

This has the result that, on tightening the bolt or nut, the part to be locked is rotated somewhat with regard to the first lock washer, until the opposed end faces come into contact with each other. It is thus ensured that the temporary adhesion between lock washer and locked part is broken and then both parts can rotate freely with respect to each other.

Figure 1 is a view of a lock washer of a first embodiment, Figure 2 is a side elevation of two such lock washers, correctly positioned and adhesively secured together, Figure 3 is a side elevation of a further embodiment, Figure 4 is a partial section on the line 4 4 of Figure 2, Figure 5 is a partial section on the line 5-5 of Figure 3, Figure 6 is a partial section through a further embodiment, and Figure 7 and 8 are side elevations of two further embodiments.

The lock washer shown in Figure 1 comprises on one side several wedge faces 20 gently inclined in the circumferential direction. The angle that these wedge faces make with a radial plane of the washer 10 is greater than the angle of the thread of the nut and bolt to be locked. Between the individual wedge faces 20 are more steeply inclined end faces 18. On the side remote from the wedge faces 20 the washer 10 is provided with a gripping face. This gripping face can be realised in any desired manner, for example with a plurality of equally spaced radially extending ribs 22.

In a first embodiment of the invention the arrangement comprises two identical lock washers. These are labelled 1 Oa and 1 Ob. So as to achieve their locking effect, the washers 1 Oa and 1 Ob must be so arranged that their wedge faces 20a and 20b face each other and the gripping faces with the ribs 22 face outwardly. So that the washers 1 0a, Ob cannot be incorrectly assembled, the two washers 1 0a, 1 Ob are secured together at selected positions by spots of adhesive 25. The adhesive 25 can be arranged on one or more of the wedge faces 20a, 20b. The two washers 1 Oa and 1 Ob form a locking unit.

Furthermore, it is advantageous if the wedge faces 20a, 20b are so adhesively secured together that the opposed end faces 1 8a and 1 8b of the two washers 1 0a, Ob are arranged with a predetermined spacing, as shown in Figure 2.

When the nut, not shown, but lying for example on the upper locking washer 1 Oa, is tightened, the ribs 22 bite into the nut and the upper washer 1 Oa as a result turns together with the nut.

The lower washer 1 Ob lies on the part of the machine to be secured and its rotation will be prevented by its ribs 22. In consequence the two washers 1 0a and 1 Ob rotate oppositely on tightening the nut, as shown by the arrows, until the end faces 1 8a and 1 8b are in contact. By this opposite rotation of the two washers 1 Oa and 1 Ob the adhesive bond 25 between the two washers is broken. This is important for proper operation of the locking arrangement. If for instance the nut is loosened as a result of vibration, it will take with it.

to some extent the upper washer 1 Oa in the direction opposite to the arrow. The lower washer 1 Ob will on the other hand be held by the part of the machine in contact with it. By the opposite relative rotation of the washers 1 Oa and 1 Ob the wedge faces 20a and 20b slide over each other so that the two washers 1 Oa and 1 Ob are forced axially apart. Since, however, the inclination of the wedge faces 20a, 20b is greater than that of the thread of the nut, the threads of the nut and bolt are tightened up and further loosening of the nut is prevented.

Any suitable adhesive can be used which will hold the two washers 10a, 1 Ob together until tightening the nut produces a relative rotation. The adhesive must be so chosen, however, that on tightening of the bolt and nut arrangement the adhesive bond is actually broken and so that eventually the described relative rotation of the two washers is no longer prevented by the adhesive connection.

In the embodiment shown in Figure 3, the two washers 1 Oa and 1 Ob are held together by adhesive 25a applied in strips bridging the peripheries 1 2a and 1 2b of the washers 1 0a, 1 Ob.

There is at least one of these adhesive bridges on the periphery 12a, 12b. They could however also be arranged on the inner faces 1 4a, 1 4b of the washers 1 0a, 1 Ob. Also in the embodiments shown in Figures 3 and 5 is provided a space between the opposed end faces 18a, 18b.

In the embodiment shown in Figure 6, the two washers 1 0a and 1 Ob each have a bevel 28a and 28b on the periphery of the wedge faces. The adhesive 26 is put in selected positions in the annular grooves formed by the two bevels 28a and 28b.

While in the embodiments shown in Figures 2-6, the part to be locked is a second identical lock washer 1 Oa, which on one side is held against rotation by the ribs 22 with an ordinary nut or bolt head, Figures 7 and 8 show that the part to be locked can also be a bolt head 27 or a nut 28.

In the embodiment shown in Figure 7 the bolt head 27 has on its underside facing the first washer 1 Ob a plurality of wedge faces 20a which contact the wedge face 20b of the first washer 1 Ob. The bolt head 27 and the washer 1 Ob are bonded together as in the previously described embodiments by individual spots of adhesive 25 or if desired also by bridging adhesive strips on thv periphery.

The embodiment shown in Figure 8 differs from the one shown in Figure 7 only in that the part to be locked is a nut 28 which is provided on its one side with wedge faces 20a and end faces 28a.

Claims

1. Nut and bolt locking arrangement comprising a lock washer which has a gripping face on one side and plurality of gently inclined wedge faces on the other side with intermediate end faces which said other side cooperates with a similar but opposed plurality of wedge faces and end faces of another part of the arrangement, the washer and the said other part of the arrangement being fixed together, the fixing being releasable on tightening up the arrangement.

2. An arrangement according to claim 1, in which the said similar but opposed plurality of wedge and end faces are on an identical washer.

3. An arrangement according to claim 1, in which the said similar but opposed plurality of wedge and end faces are on a bolt head.

4. An arrangement according to claim 1, in which the said similar but opposed plurality of wedge and end faces are on a nut.

5. An arrangement according to any one of claims 1 to 4, in which the said washer and the said other part of the arrangement are fixed together so that there is a space between the opposed end faces.

6. An arrangement according to any one of claims 1 to 5, in which the said washer and the said other part of the arrangement are adhesively secured together.

7. An arrangement according to claim 6, in which the adhesive is applied in spots or strips.

8. An arrangement according to claim 6 or claim 7, in which the adhesive is applied between opposed wedge faces.

9. An arrangement according to claim 6 or claim 7, in which the adhesive is applied as at least one strip bridging the peripheries of the said washer and the said other part of the arrangement.

10. An arrangement according to claim 6 or claim 7, in which the said washer and the said other part of the arrangement are bevelled at the periphery on the side with the wedge and end faces and adhesive is applied in the peripheral groove formed between the bevels.

11. A nut and bolt locking arrangement substantially as hereinbefore described with reference to the accompanying drawings.