AU2008200632A1

AU2008200632A1 - Locking washer

Info

Publication number: AU2008200632A1
Application number: AU2008200632A
Authority: AU
Inventors: Hannu Tapio Kangas
Original assignee: KANGAS EILA
Current assignee: Kangas Eila Anneli; Kangas John Tapio; Kangas Michael Arvi
Priority date: 2007-02-09
Filing date: 2008-02-11
Publication date: 2008-08-28
Anticipated expiration: 2028-02-11
Also published as: AU2008200632B2

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "LOCKING WASHER" The following statement is a full description of this invention, including the best method of performing it known to me/us: 001

TITLE

,.i "LOCKING WASHER" FIELD OF THE INVENTION The present invention relates to a locking washer. In particular, although not exclusively, the invention relates to a locking washer, locking Owasher insert, and locking washer assembly that be used with tapered nuts 00

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Sor non-tapered nuts.

DESCRIPTION OF THE PRIOR ART Many mechanical assemblies use threaded fasteners to attach their parts to one another. However, threaded fasteners are prone to rotate and loosen when exposed to vibration or heat fluctuations. As such, unless the threaded fastener is inspected on a regular basis, it may eventually fall out of its fastening position. This may cause the parts of the mechanical assembly to break as a result of the extra stress placed on the remaining fasteners holding the parts together, or the parts to detach from each other or fall off the mechanical assembly. As such, it has been an aim of the prior art to provide threaded fasteners that will remain in a fixed position under vibration.

Numerous locking devices have been used to secure a threaded fastener in a fixed position. For example, it is well known to use a split ring washer to retain a nut in a fixed position on a bolt, stud, or other external threaded anchor. The ends of the split ring washer are bent in opposite directions to form a spring-like spiral structure which is placed between a nut and a part on a threaded bolt. As the nut is threaded down onto the bolt, the force generated by the split ring washer in resisting compression causes one 00 2

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end of the washer to bite into the nut and the other end of the washer to bite ,.i into the part being fastened, preventing the nut from loosening under vibration. Unfortunately, split ring washers are known to slip on the surface of either the nut or part due to the rotational force generated when the nut is over-tightened. This can cause the end of the washer to burr the surface of Othe nut such that the nut must be discarded. Alternatively, the interface 00 Sbetween the washer and the part can become torn, such that the washer no longer sits flush with the part. Another problem of over-tightening the nut is that the ends of the washer can be forced apart, such that the washer becomes deformed, thus making it no longer functional for re-use.

Other locking washers are known in the art where tabs are provided around either the inner or outer circumference of the washer body and are bent in alternating directions to project from the bottom and top of the washer such that each tab will either bite into the surface of the nut or the surface of the part being fastened, locking the nut in place. However, a disadvantage of this type of washer is that it cannot be re-used since the tabs are significantly deformed after its initial use and the washer loses its functionality by no longer being able to bite into the nut or the part.

In light of the prior art, it is an object of the present invention to at least ameliorate the disadvantages and shortcomings of the prior art, or at least provide the public with a useful alternative. Further objects will be evident from the following description.

00 C SUMMARY OF THE INVENTION a In one form, although it need not be the only, or indeed the broadest form, the invention resides in a locking washer comprising: a body having a first frictional surface; and a hole extending through the body and the first frictional surface; wherein the hole is adapted to receive a bolt.

00oo Preferably, the body of the locking washer includes a second frictional surface through which the hole extends.

Alternatively, the hole of the locking washer includes a tapered section that narrows in a direction towards the first frictional surface.

Preferably, the tapered section has an angle of inclination between 200 and More preferably, the tapered section has an angle of inclination between 300 and 600.

More preferably, the tapered section has an angle of inclination between 410 and 480.

Ideally, the tapered section has an angle of inclination of 45 The locking washer may further include an insert, the insert comprising: an insert body having a frusto-conical shape and a second frictional surface; and a hole extending through the insert body and the second frictional surface, the hole adapted to receive a bolt; 00 Swherein the frusto-conical shape of the insert body is complementary to the a tapered section of the hole of the locking washer such that the insert fits inside the hole of the locking washer and the second frictional surface of the insert body is provided on an opposite side to the first frictional surface of the locking washer.

Preferably, each frictional surface is formed by a plurality of 00 oo 0projections.

More preferably, the projections comprise radially extending teeth.

More preferably, the teeth are arranged in a series of rows separated by grooves or channel sections.

Preferably, the locking washer is made of high tensile steel.

More preferably, each frictional surface is case hardened In another form, the invention resides in a locking washer assembly comprising: a locking washer having: a locking washer body; a hole extending through the locking washer body, the hole adapted to receive a bolt and includes a tapered section; and a notch located in an outside wall of the locking washer body; a tie member having: a tie member body fixedly attached to a surface of a part; a hole extending through the tie member body; and a notch located in an inside wall of the hole; a key member; 00 wherein the locking washer fits inside the hole of the tie member and is prevented from rotating inside the hole by aligning the notches adjacent each other to form a recess inserting the key member in the recess.

Preferably, the body of the locking washer comprises a first frictional surface.

OFurther features of the present invention will become apparent from 00

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Sthe following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the present invention may be readily understood and put into practical effect, reference will now be made to the accompanying illustrations wherein: FIG. 1 is a top view of a locking washer according to one embodiment of the invention; FIG. 2 is a cut-away side view of the locking washer of FIG. 1; FIG. 3 is a bottom view of the locking washer of FIG. 1; FIG. 4 is a top view of a locking washer according to another embodiment of the invention; FIG. 5 is a cut-away side view of the locking washer of FIG. 4; FIG. 6 is a bottom view of the locking washer of FIG. 4; FIG. 7 is a bottom view of a locking washer according to another embodiment of the invention; FIG. 8 is a bottom view of a locking washer according to yet another embodiment of the invention; 001 SFIG. 9 is a top view of an insert for fitting inside the locking washer of a, FIG. 4; FIG. 10 is a cut-away side view of the insert of FIG. 9; FIG. 11 is a bottom view of the insert of FIG. 9; 5 FIG. 12 is a partially cut-away exploded side view of a locking washer assembly including the locking washers of FIGS. 1 and 4; 00 o FIG. 13 is a partially cut-away side view of the locking washer assembly of FIG. 12 when assembled; FIG. 14 is a partially cut-away exploded side view of a locking washer assembly including the locking washers of FIGS. 1 and 4 and insert of FIG.

9; FIG. 15 is a partially cut-away side view of the locking washer assembly of FIG. 14 when assembled; FIG. 16 is a partially cut-away exploded side view a locking washer assembly; FIG. 17 is a partially cut-away side view of the locking washer assembly of FIG. 16 when assembled; and FIG. 18. is a top view of the locking washer assembly of FIG. 16.

DETAILED DESCRIPTION OF THE DRAWINGS FIGS. 1 to 3 show a locking washer 10 according to an embodiment of the invention.

The locking washer 10 has a circular shaped body 12 having a top frictional surface 14, a bottom frictional surface 16, and a hole 18 formed in the centre of the circular body 12 that extends through the top and bottom 00 7 Sfrictional surfaces 14,16. Each frictional surface 14,16 includes a number of a radially extending teeth 20,22 located around the inner circumference of the hole 18. The teeth 20 on the top frictional surface 14 extend from the inner circumference of the hole 18 to approximately halfway between the inner 5 circumference of the hole 18 and the outer circumference of the circular

IND

shaped body 12. The teeth 22 on the bottom frictional surface 16 extend oO 00 from the inner circumference of the hole 18 to the outer circumference of the circular shaped body 12.

FIGS. 4 to 6 show a locking washer 40 according to another embodiment of the invention.

The locking washer 40 has a circular shaped body 42 having a top planar surface 44, a bottom frictional surface 46 and a hole 48 formed in the centre of the circular body 42 extending through the top planar surface 14 and the bottom frictional surface 46. The hole 48 includes a tapered section 50 such that the circumference of the hole 48 becomes progressively smaller towards the bottom frictional surface 46. The tapered section 50 has an angle of inclination of 45 The hole 48 also includes a straight section 52.

The tapered section 50 extends from the top planar surface 44 and the straight section 52 extends from the bottom frictional surface 46 to meet between the top planar surface 44 and bottom frictional surface 46. The bottom frictional surface 46 includes a number of radially extending teeth 54 located around the circumference of the hole 48.

FIGS. 7 and 8 show two different teeth formations that may be applied to the bottom frictional surface of the locking washers of FIGS. 1 and 4.

00 0 O FIG. 7 shows the bottom frictional surface 72 comprising an inner and a outer row 74,76 of radially extending teeth which are separated by a groove FIG. 8 shows the bottom frictional surface 82 comprising an inner, middle and outer row 84,86,88 of radially extending teeth. The inner and outer rows 84,88 are separated from the middle row 86 by grooves 85,87, respectively.

00 oO FIGS. 9 to 11 show an insert 90 for fitting inside the locking washer of SFIG. 4.

The insert 90 has an insert body 92 having a top frictional surface 94, a bottom planar surface 96, and a hole 98 formed in the centre of the body 92 which extends through the top frictional surface 94 and bottom planar surface 96. The top frictional surface 94 comprises a number of radially extending teeth 100 located around the circumference of the hole 98. The insert body 92 comprises a frusto-conical section 102 having an angle of inclination that is complementary with the angle of inclination selected for the tapered section 50 of the locking washer 40. The insert 90 also includes a straight section 104 forming a spigot around an end of the insert body 92.

It is appreciated that only the frusto-conical section 102 is necessary for this embodiment of the invention to work properly. The frusto-conical section 102 extends from the top frictional surface 94 while the straight section 104 extends from the bottom planar surface 96 to meet between the top frictional surface 94 and bottom planar surface 96.

Each locking washer 10,40 and insert 90 is made from a high tensile steel, such as 4140 or K1045 steel, while each frictional surface of each 00 N locking washer 10,40 and insert 90 is case hardened to a factor of 48 to a RockwellC using a nitriding process to prevent the teeth from deforming when a compressive force is applied on each frictional surface. However, other case hardening processes can be applied to each frictional surface to prevent the teeth deforming under a compressive load.

FIGS. 12 and 13 show a locking washer assembly 120 according to 00 oo another embodiment of the invention including locking washers 10,40 for locking a nut 121A and bolt 124 in position when joining two parts 130,132 together.

A shank 126 of the bolt 124 is first passed through hole 18 of locking washer 10 such that the top frictional surface 14 of locking washer 10 is in contact with a head 128 of the bolt 124. The shank 126 is then passed through holes 134,136 located in each of the parts 130,132, respectively.

The shank 126 is finally passed through the hole 48 of the locking washer such that teeth 54 located on the bottom frictional surface 46 of the locking washer 40 face part 130. The head 128 of the bolt 124 is held in position as the nut 121A, which has a tapered section 122 conforming with the tapered section 50 of the locking washer 40, is threaded down onto the shank 126 of the bolt 124 until the two parts 130,132 press against each other. Tightening of the nut 121A generates a compressive force between the head 128 of the bolt 124 and the nut 121A. The compressive force causes the teeth 20,22 of locking washer 10 to bite into and mesh with the head 128 of the bolt 124 and part 132, respectively. This effectively turns the bolt 124 into a stud such that the bolt 124 is prevented from rotating with respect to part 132 as 00 IU O the nut 121A is further tightened. The compressive force also causes the a teeth 54 of locking washer 40 to bite into and mesh with part 130 to prevent the locking washer 40 from rotating with respect to part 130. The hardness of the locking washers 10,40 prevents the teeth 20,22,54 from deforming under the compressive force exerted between the nut 121A and bolt 124.

The conforming tapered sections 122,50 allows the nut 121A to rotate with 00 oO respect to the locking washer 40, thus preventing a rotational force from Sbeing generated that may otherwise cause either the bolt 124 or one of the locking washers 10,40 to rotate as the nut 121A is further tightened due to the teeth 20,22,54 slipping before they can mesh with the head 128 of the bolt 124 and parts 132,130, respectively. The nut 121A is finally locked in position by the compressive force generated between the tapered section 122 of the nut 121A and the tapered section 50 of the locking washer causing the nut 121A to jam inside the locking washer FIGS. 14 and 15 show a locking washer assembly 140 according to another embodiment of the invention including locking washers 10,40 and insert 90 for locking a nut 121B and bolt 124 in position when joining two parts 130,132 together.

The locking washer assembly 140 is similar to that shown in FIG. 12 except that insert 90 is used in conjunction with locking washer 40 to allow a non-tapered nut 121B to be tightened onto the bolt 124. The compressive force generated by tightening the nut 121B causes teeth 100 on the top frictional surface 94 of the insert 90 to bite into and mesh with the nut 121B to prevent the insert 90 from rotating with respect to the nut 121B. The 00 11 Sstraight section 104 reinforces the end of the frusto-conical section 102 to a prevent the compressive force generated by the nut/bolt interaction from deforming the end of the frusto-conical section 102. The nut 121B is finally locked in position by the compressive force generated between the frustoconical section 102 of the insert 90 and the tapered section 50 of the hole 48 Scausing the insert 90 to jam inside the locking washer 00oo Applying either teeth formations as shown in FIGS. 7 or 8 to the bottom frictional surface 16,46 of the locking washers 10,40 allows rust or other debris on the surface of each part 120,132 to fall into the grooves 75,85,87 of each locking washer 10,40, thus preventing the teeth 20,22,54 on each bottom frictional surface 16,46 from becoming clogged.

However, it is noted that in some applications it is preferable to use a locking washer assembly having a locking washer 10 that does not include a bottom frictional surface to allow a certain amount of slippage between the part and the head of a bolt or nut.

FIGS. 16 to 18 show a locking washer assembly 160 according to yet another embodiment of the invention for locking a tapered nut 121A and bolt 124 in position when joining two parts 130,132 together.

The locking washer assembly 160 includes a tie member 170 and a locking washer 180. The tie member 170 includes a tie member body 172 that is welded or otherwise fixedly attached to the surface of part 130. A hole 174 extends through the tie member body 172 and includes a notch 176 located in an inside wall 178 of the tie member 170. The locking washer 180 includes a locking washer body 182, a hole 184 including a tapered section 00 12

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186 extending through the locking washer body 182, and a notch 188 located in an outside wall 190 of the locking washer 180. The hole 174 of the tie member 170 is shaped to allow the locking washer 180 to be inserted inside the tie member body 172. The locking washer 180 is prevented from rotating inside the hole 174 of the tie member 170 by aligning the notches 176,188 Oadjacent each other to form a recess 192 and inserting a key member 194 00 Sinto the recess 192. It is to be appreciated that more than one recess 192 can be formed to evenly distribute rotational force exerted between the between the tie member 170 and locking washer 180.

While the assemblies of FIGS. 12 and 14 show that the different locking washer embodiments are used in combination with each other, it is to be appreciated that they may also be used independently. It should also be appreciated that the locking washer of FIG. 1 may be used in combination with the locking washer assembly of FIG. 16 to lock the head of the bolt in position, while the insert of FIG. 9 may be used independently for locking a non-tapered nut in a corresponding counter-sunk recess.

The first embodiment of the invention effectively turns a bolt into a stud such that the bolt is prevented from rotating by the locking washer as the nut is tightened. This also provides the advantage that the nut threaded on the bolt may be loosened without having to hold the head of the bolt in place.

The second embodiment of the invention allows a compressive force to be applied perpendicularly to each surface as the nut is tightened instead of rotationally, such that the pressure of the teeth exerted on the part causes 00 the bottom frictional surface of the locking washer and/or the top frictional surface of the insert to mesh to the part and/or nut, respectively. This arises from the interaction of the taper arrangement between either the washer/nut, the washer/insert assembly, or the insert/countersunk hole allowing the tapered sections to rotate with respect to each other until the compressive Sforce generated by the nut/bolt interaction finally locks the tapered sections 00 Stogether in a complementary fashion. As such, the invention may be used to lock a nut in place without a destructive rotational force being developed between the interface of the nut/washer and/or the washer/part.

The invention is reusable since each frictional surface of each locking washer and insert are case hardened to prevent the teeth deforming under the compressive force generated by the nut/bolt interaction. Accordingly, the invention is an excellent locking arrangement in any application where nuts and/or bolts are used and is particularly useful to prevent both left and right hand threaded nuts/bolts from unscrewing in high vibration or fluctuating heat environments.

While the shape of the body of each locking washer is shown to be circular, it should be appreciated that it may also be triangular, quadratic, pentagonal, a hexagonal, or some other shape.

Finally, it should be appreciated that a nylon sleeve may be inserted in either the hole of the insert or the hole of the locking washer in order that a number of different sized bolts may be used with each locking washer or insert.

00 14 SThroughout the description of this specification, the word "comprise" a and variations of that word such as "comprises" and "comprising", are not intended to exclude other additives, components, integers or steps.

Throughout the specification the aim has been to describe the invention without limiting the invention to any one embodiment or specific collection of features. Persons skilled in the relevant art may realize 00 oo variations from the specific embodiments that will nonetheless fall within the scope of the invention.

Claims

2. The locking washer of claim 1, wherein the body includes a second frictional surface through which the hole extends.
3. The locking washer of claim 1, wherein the hole includes a tapered section that narrows in a direction towards the first frictional surface.
4. The locking washer of claim 3, wherein the tapered section has an angle of inclination between 200 and 700 The locking washer of claim 3, wherein the tapered section has an angle of inclination between 300 and 600.
6. The locking washer of claim 3, wherein the tapered section has an angle of inclination between 410 and 48'.
7. The locking washer of claim 3, wherein the tapered section has an angle of inclination of 45'
8. The locking washer of claim 3, wherein the locking washer includes an insert, the insert comprising: an insert body having a frusto-conical shape and a second frictional surface; and a hole extending through the insert body and the second frictional surface, the hole adapted to receive a bolt; 00 It) Swherein the frusto-conical shape of the insert body is a complementary to the tapered section of the hole of the locking washer such that the insert fits inside the hole of the locking washer and the second frictional surface of the insert body is provided on an opposite side to the first frictional surface of the locking washer.
9. The locking member of any of the preceding claims, wherein each 00 oo frictional surface is formed by a plurality of projections. The locking member of claim 9, wherein the projections comprise radially extending teeth.
11. The locking member of claim 10, wherein the teeth are arranged in a series of rows separated by grooves or channel sections.
12. The locking washer of any of the preceding claims, wherein the locking washer is made of high tensile steel.
13. The locking washer of claim 12, wherein each frictional surface is case hardened
14. A locking washer assembly comprising: a locking washer having: a locking washer body; a hole extending through the locking washer body, the hole adapted to receive a bolt and includes a tapered section; and a notch located in an outside wall of the locking washer body; a tie member having: 00 1 Sa tie member body fixedly attached to a surface of a a part; a hole extending through the tie member body; and a notch located in an inside wall of the hole; a key member; wherein the locking washer fits inside the hole of the tie 00 member and is prevented from rotating inside the hole by aligning the notches adjacent each other to form a recess inserting the key member in the recess.
15. The locking washer assembly of claim 14, wherein the body of the locking washer comprises a first frictional surface.
16. The locking washer as defined in claim 1 with reference to the accompanying drawings of FIGS 1 to 3.
17. The locking washer as defined in claim 1 with reference to the accompanying drawings of FIGS 4 to 11.
18. The locking washer as defined in claim 14 with reference to the accompanying drawings of FIGS 16 to 18.