GB2539395A

GB2539395A - Improved nut assembly

Info

Publication number: GB2539395A
Application number: GB1510306.2A
Authority: GB
Inventors: Tan Andrew
Original assignee: MAKE IT FAIL Ltd
Current assignee: MAKE IT FAIL Ltd
Priority date: 2015-06-12
Filing date: 2015-06-12
Publication date: 2016-12-21
Anticipated expiration: 2035-06-12
Also published as: GB201510306D0; GB2539395B

Abstract

A clamping mechanism comprises a nut 100, a clamp plate 200, a bolt 300 and a block 47. The nut 100 has an axial bore with a screw thread 114 formed on an inner surface of the bore. The bolt 300 has a pair of arms 332a, 332b and a cross piece 336 joining the arms 332a, 332b together. The arms 332a, 332b have a screw thread 334 formed on an outer surface of the arms 332a, 332b corresponding to the screw thread 114 of the nut 100. The clamp plate 200 has an elongate body 225 narrower than the separation between the arms 332a, 332b so as to fit between the arms 332a, 332b. The block 47 can be engaged with the nut 100 for movement therewith, the block 47 extending between the arms 332a, 332b of the bolt 300. The block 300 opposes flexure of the arms 332a, 332b towards each other as the nut 100 is screwed onto the bolt 300.

Description

IMPROVED NUT ASSEMBLY

The present invention concerns an improved nut assembly, which is particularly suited for use in a clamping mechanism, as well as a clamping mechanism comprising such a nut assembly.

WO 2013/132243, which is also in the name of the present applicant, describes a container holder and a clamping mechanism. The clamping mechanism described therein is reproduced below in Figs. 1 to 4. This known clamping mechanism has three main components, namely a nut, a clamp plate and a bolt. For better understanding of the present invention, the construction and operation of this clamping mechanism will now be briefly described with reference to Figs. 1 to 4. As may be seen therein, the clamping mechanism comprises a nut 10, a clamp plate 20 and a bolt 30. The nut 10 has an axial bore 12 with a concave screw thread 14 formed on an inner surface of the bore 12. The bolt 30 comprises two arms 32a, 32b, each of which has a convex screw thread 34 formed on an outer surface thereof. The axial bore 12 of the nut 10 and the arms 32a, 32b of the bolt 30 are sized relative to each other such that if the arms 32a, 32b are inserted into the bore 12, the convex screw thread 34 on the arms 32a, 32b engages with the concave screw thread 14 in the bore 12.

The clamp plate 20 has an elongate main body 25 with a pair of resilient arms 22a, 22b projecting perpendicularly from a rear surface 26 thereof. Each arm 22a, 22b has a respective radially outwardly projecting tang 24a, 24b formed at an end thereof. The tangs 24a, 24b are spaced apart from each other such that if the arms 22a, 22b are inserted into the axial bore 12 of the nut 10, the tangs 24a, 24b come into contact with the screw thread 14 in the bore 12. Thus, as the arms 22a, 22b are inserted further into the bore 12, the screw thread 14 pushes on the tangs 24a, 24b, which causes the arms 22a, 22b to flex inwardly towards each other. The tangs 24a, 24b are also separated from the rear surface 26 of the clamp plate 20 by a distance greater than a depth of the screw thread 14. Thus, as the arms 22a, 22b continue to be inserted into the bore 12, the tangs 24a, 24b pass completely through the screw thread 14 and engage with an outer face of a final turn of the screw thread 14, causing the resilient arms 22a, 22b to spring back into their unflexed condition. Shortly thereafter, the rear surface 26 of the elongate main body 25 of the clamp plate 20 comes into contact with and abuts against a front face 16 of the nut 10. Thus, the arms 22a, 22b of the clamp plate 20 cannot be inserted any further into the bore 12 of the nut 10. Therefore, by inserting the arms 22a, 22b into the bore 12, the clamp plate 20 can be engaged with the nut 10 in such a manner that it can rotate freely within the bore 12 of nut 10 about a central axis of bore 12, but cannot be removed axially from bore 12 without flexing the arms 22a, 22b inwardly towards each other enough to disengage the tangs 24a, 24b from the outer face of the final turn of the screw thread 14. In the drawings, Fig. 1 shows the clamp plate 20 disengaged from the nut 10, whereas Figs. 2 to 4 all show the clamp plate 20 thus engaged with the nut 10.

In order to clamp the clamping mechanism of Figs. 1 to 4 to another body, an elongate part of that other body may be inserted between the arms 32a, 32b of bolt 30. With clamp plate 20 and nut 10 already engaged as just described, the concave screw thread 14 of nut 10 can then be introduced to the convex screw thread 34 of bolt 30 by moving nut 10 in the direction indicated by the arrows labelled "A" in Figs. 2 and 3. Elongate main body 25 of clamp plate 20 has a width such that it may fit comfortably between the pair of arms 32a, 32b of the bolt 30. This creates an enclosed, generally cylindrical through-hole labelled "T" in Fig. 4, which surrounds the elongate part of the other body by the elongate main body 25 of the clamp plate 20 and the two arms 32a, 32b, as well as by a cross piece 36 of the bolt 30 which joins the two arms 32a, 32b together. As the screw thread 14 of nut 10 is tightened on to the screw thread 34 of bolt 30, elongate main body 25 of clamp plate 20 is retained between the arms 32a, 32b of bolt 30 and prevented by them from rotating relative to bolt 30. Thus, elongate main body 25 remains substantially parallel to the elongate part of the other body as nut 10 is rotated. The elongate main body 25 of clamp plate 20 therefore advances upon the elongate part of the other body until it comes into contact with it. A front surface of the elongate main body 25 is provided with a compressible resilient pad 28, which engages the elongate part of the other body in order to grip it as the nut 10 is advanced further in the direction of arrows "A". The clamping mechanism is therefore clamped to the elongate part of the other body. Strengthening ribs 38 formed on respective inner surfaces of the arms 32a, 32b and of the cross piece 36 of bolt 30 are provided to counter deformation of the bolt 30 as the pressure of the nut 10 upon the other body is increased.

However, although such a clamping mechanism is generally excellent for attachment to an elongate part of another body as just described, it has been found that if a user attempts to overtighten nut 10, this can cause flexure of the arms 32a, 32b inwardly towards each other, possibly leading to disengagement of the two screw threads 14, 34 from each other, as well as the possibility of them cross-threading. The present invention therefore aims to address this problem and to provide an improved nut assembly for such a clamping mechanism, as well as to provide an improved clamping mechanism.

Accordingly, in a first aspect, the present invention provides a clamping mechanism having a longitudinal axis and comprising a nut, a bolt, a clamp plate and a block. The nut has an axial bore with a concave screw thread formed on an inner surface of the bore. The bolt comprises a pair of arms and a cross piece joining the arms together. The arms of the bolt have a convex screw thread corresponding to the concave screw thread in the bore of the nut formed on an outer surface of said arms. The clamp plate has an elongate main body narrower than the separation between an inner surface of each of the arms of the bolt so as to be able to fit between said arms. The block can be engaged with said nut for movement therewith, the block extending between the inner surfaces of the arms of the bolt. The block is also locatable between the arms of the bolt when the nut is screwed on to the bolt. Thus the block opposes flexure of the arms towards each other as the nut is screwed on to the bolt.

In a preferred embodiment of this clamping mechanism, the elongate main body of the clamp plate is wider than the bore of the nut in a first radial direction and narrower than the separation between the inner surfaces of the arms of the bolt in a second radial direction. The block is also narrower radially than the bore of the nut in the first radial direction and has a width substantially equal to but less than the separation between the inner surfaces of the is arms in the second radial direction. The block is part of a cap having a main body portion wider radially than the bore of the nut. Furthermore, the clamp plate and the cap are rigidly connectable with each other on axially opposing sides of the nut through the bore of the nut, such that the block is located inside the bore of the nut when the clamp plate and the cap are rigidly connected together. Thus the cap does not rotate as the nut is screwed on to the bolt.

The above clamping mechanism therefore not only prevents flexure of the arms of the bolt towards each other, but also provides the following bonus effect. Since the block is maintained in the same orientation by the arms of the bolt as the nut is screwed on to the bolt, the nut can be screwed on to the bolt, and the cap will maintain the same orientation as the block. Thus if a front surface of the cap is provided with indicia, such as a logo, name, trade mark and/or instructions, these indicia can be maintained in the same orientation even if the nut is rotated.

Preferably, the block comprises a strengthening rib aligned substantially parallel with the second radial direction. Since this is also parallel to a shortest distance between the arms of the bolt if the block is located between the arms of the bolt, this helps to prevent deformation of the block and keep it rigid.

It is also preferred that the arms of the bolt should comprise strengthening ribs aligned substantially parallel to a shortest distance between the arms of the bolt. This also helps to prevent deformation of the arms and to keep them rigid.

If the bolt does comprise such strengthening ribs, the clamp plate may also comprise a side arm on each of a left and right side of the clamp plate locatable in a gap between adjacent ones of the strengthening ribs on the arms of the bolt. If so, the side arms should have a length in a direction parallel to the shortest distance between the arms of the bolt substantially equal to but less than the separation between the inner surfaces of said arms, and a thickness in a direction parallel to the shortest distance between adjacent ones of the strengthening ribs substantially equal to but less than a separation between the adjacent ones of the strengthening ribs. These side arms helps to guide the clamp plate between the arms of the bolt as the nut is screwed on to the bolt, and to prevent rotation of the clamp io plate as the nut is rotated about its axis.

Preferably, the bolt may comprise an end stop on an inner surface of the cross piece, the end stop being arranged to abut a front surface of the clamp plate before the arms of the bolt come into contact with a rear surface of the cap, as the nut is screwed on to the bolt. This helps to ensure that the cap is not damaged or deformed by the arms of the bolt as the nut is is screwed on to the bolt.

Preferably, the clamp plate and the cap may be rigidly connected with each other on opposing sides of the nut by a snap-fit mechanism of the clamp plate and the cap contained within the bore of the nut. This ensures that the clamp plate and the cap can be quickly and conveniently connected to each other during manufacture.

It is also preferable that the clamp plate and the nut can be engaged with each other. This can be achieved in the following manner. The elongate main body of the clamp plate may have a plurality of resilient arms projecting perpendicularly from a rear surface thereof, each of said arms having a respective radially outwardly projecting tang formed thereon. If so, a separation of the tangs from each other should be such that if the arms are inserted into the bore of the nut in a first axial direction, the tangs come into contact with the screw thread in the bore, whereby the screw thread can push on the tangs causing the arms to flex radially inwardly towards each other. A distance of the tangs from the rear surface of the clamp plate should also be greater than an axial depth of the screw thread, such that if the arms are inserted into the bore of the nut in the first axial direction, the tangs can pass completely through the screw thread and engage with an outer face of a final turn of the screw thread, causing the arms to spring back into their unflexed condition.

Conveniently, the clamp plate and the cap can then be rigidly connected with each other on axially opposing sides of the nut through the bore of the nut in the following manner. The cap should have a plurality of resilient arms projecting perpendicularly from a rear surface thereof, each of said arms having a respective radially outwardly projecting tang formed thereon, and the clamp plate should have a plurality of apertures each for receiving a respective one of the tangs on the arms of the cap. A separation of the tangs on the cap arms from each other should be greater than a separation of the corresponding apertures in the clamp plate from each other, such that if the cap arms are inserted into the bore of the nut in a second axial direction opposite to the first axial direction, the tangs on the cap arms come into contact with the arms on the clamp plate, whereby the arms on the clamp plate can push on the tangs of the cap arms, causing the cap arms to flex radially inwardly towards each other. A distance of the tangs on the cap arms from the rear surface of the to cap should also be greater than a distance of the corresponding apertures in the clamp plate from the tips of the arms on the clamp plate, such that if the cap arms are inserted into the bore of the nut in the second axial direction, the tangs on the cap arms can engage with the corresponding apertures in the clamp plate, causing the cap arms to spring back into their unflexed condition. Finally, a distance of the rear surface of the cap from the rear surface of the clamp plate when the tangs on the cap arms are engaged with the corresponding apertures in the clamp plate should be greater than an axial depth of the nut.

Such an arrangement as just described for rigidly connecting the clamp plate and the cap with each other allows these two components to be quickly and conveniently connected to each other in a simple snap-fit operation, which is not easily reversible, ensuring that the clamp plate and the cap remain thus connected during use of the clamping mechanism.

As mentioned above, the front surface of the cap may be provided with indicia, such as a logo, name, trade mark and/or instructions. If so, the clamping mechanism can be manufactured by a method comprising injection moulding the cap using a mould tool comprising a first tool insert for forming the indicia on the front surface of the cap, wherein the first tool insert has a mould for forming first indicia thereon, and the first tool insert is interchangeable with a second tool insert having a mould for forming second, different indicia thereon. This manufacturing method allows the indicia on the front surface of the cap to be changed quickly and easily by interchanging the tool inserts.

In a second aspect, the invention also provides a nut assembly having a longitudinal axis and comprising a nut, a first co-operating component and a second co-operating component.

The nut has an axial bore with a concave screw thread formed on an inner surface of said bore. The first co-operating component has an elongate main body wider than the bore of the nut in a first radial direction, and also has an axial portion which can be inserted into the bore of the nut in a first axial direction. The second co-operating component has a main body portion wider radially than the bore of the nut and an axial portion insertable into the bore of the nut in a second axial direction opposite to the first axial direction. The first and second co-operating components are rigidly connected with each other on axially opposing sides of the nut by connecting the axial portion of the first co-operating component with the axial portion of the second co-operating component through the bore of the nut. The fact that the first and second co-operating components are both wider than the bore of the nut as just described means that if they are rigidly connected on opposing sides of the nut, the nut cannot be removed from between them. The concave screw thread in the bore of the nut corresponds to a convex screw thread formed on an outer surface of a pair of arms, and the elongate main body of the first co-operating component is narrower than the separation between an inner surface of each of said arms in a second radial direction. Thus the elongate main body can be introduced between said arms, and the concave screw thread can be brought into contact with the convex screw thread. A part of the first and second cooperating components can then be maintained in the same orientation by contact with said arms if the nut is rotated about the longitudinal axis. Thus the nut can be screwed onto said arms without changing the orientation of the main body portion of the second co-operating component relative to the arms. This allows any indicia on the main body portion of the second co-operating component to maintain their correct orientation as the nut is turned.

Preferably, the first and second co-operating components of the nut assembly are rigidly connected with each other on opposing sides of the nut by a snap-fit mechanism of the first and second co-operating components contained within the bore of the nut. This allows the first and second co-operating components to be quickly and conveniently connected to each other during manufacture.

In a preferred embodiment of the nut assembly, the first co-operating component comprises a clamp plate, and the axial portion of the first co-operating component comprises a plurality of resilient arms projecting perpendicularly from a rear surface of the clamp plate, each of said arms having a respective radially outwardly projecting tang formed thereon. In this embodiment, a separation of the tangs from each other is such that if the arms are inserted into the bore of the nut in the first axial direction, the tangs come into contact with the screw thread in the bore, whereby the screw thread can push on the tangs causing the arms to flex radially inwardly towards each other. A distance of the tangs from the rear surface of the clamp plate is greater than an axial depth of the screw thread, such that if the arms are inserted into the bore of the nut in the first axial direction, the tangs can pass completely through the screw thread and engage with an outer face of a final turn of the screw thread, causing the arms to spring back into their unflexed condition. This arrangement allows the first co-operating component to be engaged with the nut.

Preferably, the second co-operating component also comprises a cap, and the axial portion of the second co-operating component comprises a plurality of resilient arms projecting perpendicularly from a rear surface of the cap, each of said arms having a respective radially outwardly projecting tang formed thereon. The clamp plate also has a plurality of apertures each for receiving a respective one of the tangs on the arms of the cap, and a separation of the tangs on the cap arms from each other is greater than a separation of the corresponding apertures in the clamp plate from each other, such that if the cap arms are inserted into the bore of the nut in the second axial direction, the tangs on the cap arms come into contact with the arms on the clamp plate, whereby the arms on the clamp plate can push on the tangs of the cap arms, causing the cap arms to flex radially inwardly towards each other. In this embodiment, a distance of the tangs on the cap arms from the rear surface of the cap is greater than a distance of the corresponding apertures in the clamp plate from the tips of the arms on the clamp plate, such that if the cap arms are inserted into the bore of the nut in the second axial direction, the tangs on the cap arms can engage with the corresponding apertures in the clamp plate, causing the cap arms to spring back into their unflexed condition, and a distance of the rear surface of the cap from the rear surface of the clamp plate when the tangs on the cap arms are engaged with the corresponding apertures in the clamp plate is greater than an axial depth of the nut. This allows the first and second cooperating components of the nut assembly to be rigidly connected with each other on axially opposing sides of the nut through the bore of the nut in a simple snap-fit operation, which is not easily reversible, ensuring that the first and second co-operating components remain thus connected if the nut is rotated.

The front surface of the second co-operating component may have indicia thereon, such as a logo, name, trade mark and/or instructions. If so, the nut assembly can be manufactured by a method comprising injection moulding the second co-operating component using a mould tool comprising a first tool insert for forming the indicia on the front surface of the second co-operating component, wherein the first tool insert has a mould for forming first indicia thereon, and the first tool insert is interchangeable with a second tool insert having a mould for forming second, different indicia thereon. This manufacturing method allows the indicia on the front surface of the second co-operating component to be changed quickly and easily by interchanging the tool inserts.

It is preferable that the part of the first and second co-operating components which can be maintained in the same orientation by contact with the arms comprises a block of the second co-operating component locatable between the arms. If so, the block should be narrower radially than the bore of the nut in the first radial direction and have a width substantially equal to but less than a separation between an inner surface of each of the arms in the second radial direction. Thus, with such an arrangement, the block is able to oppose flexure of the arms towards each other if the concave screw thread in the bore of the nut is screwed on to the aforementioned convex screw thread.

Preferably, the block may comprise one or more strengthening ribs aligned substantially parallel with the second radial direction. Since this is also parallel to a shortest distance between the aforementioned arms if the block is located between the arms, this helps to prevent deformation of the block and keep it rigid.

Preferably, the part of the first and second co-operating components which can be to maintained in the same orientation by contact with the arms comprises a part of the first co-operating component which can engage with said arms to be axially guided thereby. Thus, according to this embodiment, if the first co-operating component is maintained in a selected orientation by being axially guided by the arms, the nut can be rotated about the longitudinal axis, and the second co-operating component will maintain the same orientation as the first co-operating component as the first and second co-operating components are rigidly connected to each other.

Further features and advantages of the present invention will become apparent from the following detailed description, which is given by way of example and in association with the accompanying drawings, in which: Fig. 1 is an exploded isometric view of a known clamping mechanism; Fig. 2 is a first isometric view of the clamping mechanism of Fig. 1 in a partially assembled state; Fig. 3 is a second isometric view of the clamping mechanism of Fig. 1 in a partially assembled state; Fig. 4 is a plan view of a lateral section through the clamping mechanism of Fig. 1 in an assembled state; Fig. 5 is an isometric view of a lateral section through a clamping mechanism according to an embodiment of the invention: Fig. 6 is a first isometric view of a vertical section through the clamping mechanism of Fig. 5; Fig. 7 is a second isometric view of a vertical section through the clamping mechanism of Fig. 5; Fig. 8 is a first isometric view of a cap, which is a component of the clamping mechanism of Fig. 5; Fig. 9 is a second isometric view of the cap shown in Fig. 8; Fig. 10 is an isometric view of a bolt, which is a component of the clamping mechanism of Fig. 5; Fig. 11 is an isometric view of the cap shown in Figs. 8 and 9 assembled with the bolt shown in Fig. 10; Fig. 12 is an isometric view of a clamp plate, which is a component of the clamping mechanism of Fig. 5; Fig. 13 is an elevationsl view of the clamp plate of Fig. 12 assembled with the bolt shown in Fig. 10; and Fig. 14 is an isometric view of the clamp plate shown in Figs. 12 and 13 assembled with the cap shown in Figs. 8 and 9 and with the bolt shown in Figs. 10, 11 and 13.

Referring firstly to Figs. 5, 6 and 7, there is shown a series of isometric views of a clamping mechanism according to an embodiment of the invention in a fully assembled state and sectioned to show various features of this mechanism. The clamping mechanism comprises a nut 100, a clamp plate 200, a cap 40 and a bolt 300. The nut 100 has an axial bore 112 with a concave screw thread 114 formed on an inner surface of the bore. The clamp plate has an elongate main body 225, which, as may be seen in Figs. 6 and 7, is wider than the bore 112 of the nut 100 in a first radial direction thereof, which is the vertical direction x-x' shown in Figs. 5, 6 and 7. This means that the elongate main body 225 of the clamp plate 200 is unable to pass axially through the bore 112 of the nut 100. Projecting perpendicularly from a rear surface 226 of the clamp plate 200 is a pair of resilient arms 222a, 222b. Each of these arms has a respective radially outwardly projecting tang 224a, 224b formed thereon. A front surface 227 of the clamp plate 200 is provided with a compressible resilient pad 228 thereon. There is also a side arm 229a, 229b on each of a left and right side of the clamp plate 200.

The clamp plate 200 engages with the nut 100 in the following manner. A separation of the tangs 224a, 224b from each other is such that if the arms 222a, 222b are inserted into the bore 112 of the nut 100 in a first axial direction, the tangs 224a, 224b come into contact with the screw thread 114 in the bore 112. This allows the screw thread 114 to push on the tangs 224a, 224b, causing the arms 222a, 222b to flex radially inwardly towards each other. A distance of the tangs 224a, 224b from the rear surface 226 of the clamp plate 200 is greater than an axial depth of the screw thread 114, such that if the arms 222a, 222b are inserted into the bore 112 of the nut 100 further in the first axial direction, the tangs 224a, 224b pass completely through the screw thread 114 and engage with an outer face of a final turn of the screw thread 114, causing the arms 222a, 222b to spring back into their unflexed condition.

The cap 40 has a main body portion 45 which is wider radially than the axial bore 112 of the nut 100. This means that the main body portion 45 of the cap 40 is also unable to pass axially through the bore 112 of the nut 100. As may best be seen in Fig. 5, the cap 40 has a block 47 depending from the main body portion 45 of the cap. The block 47 is narrower is radially than the bore of the nut 100, so that it may pass into the bore of the nut. The block 47 also comprises several strengthening ribs 46, which are aligned substantially parallel with the second radial direction. The cap 40 has a rear surface 41 and a front surface 43, with a pair of resilient arms 42a, 42b projecting perpendicularly from the rear surface 41. Each of these arms 42a, 42b also has a respective radially outwardly projecting tang 44a, 44b formed thereon.

Figs. 8 and 9 show the cap 40 in greater detail. The direction of inserting the cap 40 into the bore 112 of the nut 100 is shown in Fig. 8 by the arrows labelled "A". As may be seen in Fig. 9, the front surface 43 of the cap 40 has indicia 50 thereon, which in this case, by way of example only, comprises the names of two websites. The indicia 50 may be moulded into the front surface 43 of the cap 40. These indicia 50 may be quickly and easily altered during manufacture of the cap by injection moulding the cap using a mould tool comprising an interchangeable tool insert for forming the indicia on the front surface of the cap. Thus, if a first tool insert having a mould for forming first indicia thereon is used initially, and the first tool insert is then interchanged with a second tool insert having a mould for forming second, different indicia thereon, the indicia on the front surface of the cap can be changed quickly and easily to match the second tool insert instead.

The clamp plate 200 and the cap 40 can be rigidly connected with each other on axially opposing sides of the nut 100 through the bore 112 of the nut, as will be described in greater detail below.

Fig. 10 shows the bolt 300 in greater detail. The bolt 300 comprises a pair of arms 332a, 332b and a cross piece 336 which joins the arms together. The arms 332a, 332b have a convex screw thread 334 corresponding to the concave screw thread 114 in the bore of the nut 100 formed on an outer surface of the arms. The arms 332a, 332b also have several strengthening ribs 338 on them. These ribs are aligned substantially parallel to a shortest distance between the arms. The bolt also has a plurality of end stops 337 formed on an inner surface of the cross piece 336. These end stops are arranged to abut the front surface 227 of the clamp plate 200 before the arms 332a, 332b of the bolt come into contact with the rear surface 41 of the cap 40, as the nut 100 is screwed on to the bolt. The inner surface of the cross piece 336 is also provided with a compressible resilient pad 339 thereon, which faces the compressible resilient pad 228 of the clamp plate 200, so that an elongate part of another body can be gripped between the two resilient pads 228, 339, as the nut 100 is screwed on to the bolt.

As may be seen in Fig. 5, the elongate main body 225 of the clamp plate 200 is narrower than the separation between an inner surface of each of the arms 332a, 332b of the bolt 300 in a second radial direction y-y'. Thus, the elongate main body 225 of the clamp plate 200 is able to fit comfortably between the arms 332a, 332b of the bolt 300. Fig. 11 shows how the block 47 of the cap 40 has a width represented by the double-headed arrow labelled "B" in Fig. 11, which is substantially equal to but slightly less than the separation between the inner surfaces of the arms 332a, 332b of the bolt 300. Thus when the block 47 is located between the arms 332a, 332b of the bolt when the nut 100 is screwed on to the bolt, the block 47 opposes flexure of the arms 332a, 332b towards each other as the nut is screwed on to the bolt.

How the clamp plate 200 and the cap 40 can be rigidly connected with each other will now be described with reference to Figs. 12 and 13. The clamp plate 200 and the cap 40 can be rigidly connected to each other on axially opposing sides of the nut 100 by means of a snap-fit mechanism, part of which is on the clamp plate 200 and part of which is on the cap 40, all of which can be contained within the bore 112 of the nut 100. As may be seen in Fig. 12, the clamp plate 200 has a plurality of apertures 223a, 223b, each for receiving a respective one of the tangs 44a, 44b on the arms 42a, 42b of the cap 40. A separation of these tangs 44a, 44b from each other is greater than a separation of the corresponding apertures 223a, 223b in the clamp plate 200 from each other. Thus if the cap arms 42a, 42b are inserted into the bore 112 of the nut 100 in a second axial direction opposite to the first axial direction mentioned above, the tangs 44a, 44b on the cap arms 42a, 42b come into contact with the arms 222a, 222b on the clamp plate 200, and the arms 222a, 222b on the clamp plate push on the tangs 44a, 44b of the cap arms 42a, 42b, causing the cap arms 42a, 42b to flex radially inwardly towards each other. A distance of the tangs 44a, 44b on the cap arms 42a, 42b from the rear surface 41 of the cap 40 is greater than a distance of the corresponding apertures 223a, 223b in the clamp plate 200 from the tips of the arms 222a, 222b on the clamp plate 200, such that if the cap arms 42a, 42b are inserted further into the bore 112 of the nut 100 in the second axial direction, the tangs 44a, 44b on the cap arms 42a, 42b engage with the corresponding apertures 223a, 223b in the clamp plate 200, causing the cap arms 42a, 42b to spring back into their unflexed condition, as shown in the ring labelled "C" in Fig. 13.

The distance of the rear surface 41 of the cap 40 from the rear surface 226 of the clamp plate 200 when the tangs 44a, 44b on the cap arms 42a, 42b are engaged with the corresponding apertures in the clamp plate 200 is greater than an axial depth of the nut 100. Thus, if the elongate main body 225 of the clamp plate 200 is maintained in a selected orientation, once the clamp plate 200 and the cap 40 are rigidly connected to each other as just described, the nut 100 can be rotated about a central axis of the bore 112, and the cap 40 will maintain the same orientation as the clamp plate 200.

The structure and function of the side arms 229a, 229b on each of a left and right side of the clamp plate 200 will now be described with reference to Fig. 14. As may be seen inside the circles labelled D in Fig. 14, the side arms 229a, 229b can be located in a gap between adjacent ones of the strengthening ribs 338 on the arms 332a, 332b of the bolt 300. Each side arm has a length in a direction parallel to the shortest distance between the arms 332a, 332b of the bolt 300 substantially equal to but slightly less than the separation between the inner surfaces of the arms 332a, 332b. Each side arm also has a thickness in a direction parallel to the shortest distance between adjacent ones of the strengthening ribs 338 substantially equal to but slightly less than a separation between the adjacent ones of the strengthening ribs 338. This allows the side arms to help to guide the clamp plate 200 between the arms 332a, 332b of the bolt 300 as the nut 100 is screwed on to the bolt, and helps to prevent rotation of the clamp plate 200 as the nut is 100 rotated about its axis.

An embodiment of a nut assembly according to the invention comprises a nut 100, a clamp plate 200 and a cap 40 as described above, wherein the clamp plate 200 provides a first cooperating component and the cap 40 provides a second co-operating component of the nut assembly. In such a case, the nut 100 can be screwed onto the arms of a bolt such as bolt 300 without changing the orientation of the main body portion 45 of the second co-operating component 40 relative to the arms. Thus, if the indicia 50 on the cap 40 are correctly oriented so as to be readable before the nut 100 is screwed on to the bolt 300, the indicia 50 will maintain the same, correct orientation as the nut is screwed on to the bolt.

Whereas various optional features of the invention have been described above in particular combinations by way of example only, such optional features may be combined in other ways without restriction to the scope of the invention, which is defined by the appended claims.

Claims

CLAIMSA clamping mechanism having a longitudinal axis (z-z') and comprising: a nut (100) having an axial bore (112) with a concave screw thread (114) formed on an inner surface of the bore (112); a bolt (300) comprising a pair of arms (332a, 332b) and a cross piece (336) joining the arms (332a, 332b) together; the arms (332a, 332b) having a convex screw thread (334) corresponding to the concave screw thread (114) in the bore (112) of the nut (100) formed on an outer surface of said arms; a clamp plate (200) having an elongate main body (225) narrower than the separation between an inner surface of each of the arms (332a, 332b) of the bolt (300) so as to be able to fit between said arms (332a, 332b); and a block (47) which can be engaged with said nut (100) for movement therewith, the block (47) extending between the inner surfaces of the arms (332a, 332b) of the bolt (300); wherein the block is locatable between the arms (332a, 332b) of the bolt (300) when the nut (100) is screwed on to the bolt (300), whereby the block opposes flexure of the arms (332a, 332b) towards each other as the nut (100) is screwed on to the bolt (300).
2. A clamping mechanism according to claim 1, wherein: the elongate main body (225) of the clamp plate (200) is wider than the bore (112) of the nut (100) in a first radial direction (x-x') and narrower than the separation between the inner surfaces of the arms (332a, 332b) of the bolt (300) in a second radial direction (y-y'); the block (47) is narrower radially than the bore (112) of the nut (100) in the first radial direction (x-x') and has a width substantially equal to but less than the separation between the inner surfaces of the arms (332a, 332b) in the second radial direction (y-y'); the block is part of a cap (40) having a main body portion (45) wider radially than the bore (112) of the nut (100); the clamp plate (200) and the cap (40) are rigidly connectable with each other on axially opposing sides of the nut (100) through the bore (112) of the nut (100) such that the block is located inside the bore (112) of the nut (100) when the clamp plate (200) and the cap (40) are rigidly connected together; whereby the cap (40) does not rotate as the nut (100) is screwed on to the bolt (300).
3. A clamping mechanism according to claim 1 or claim 2, wherein the block (47) comprises a strengthening rib (46) aligned substantially parallel with the second radial direction (y-y').
4. A clamping mechanism according to any one of the preceding claims, wherein the arms (332a, 332b) of the bolt (300) comprise strengthening ribs (338) aligned substantially parallel to a shortest distance between the arms (332a, 332b) of the bolt (300).
5. A clamping mechanism according to claim 4, wherein: the clamp plate (200) comprises a side arm (229a, 229b) on each of a left and right side thereof locatable in a gap between adjacent ones of the strengthening ribs (338) on the arms (332a, 332b) of the bolt (300); the side arms having a length in a direction parallel to the shortest distance between the arms (332a, 332b) of the bolt (300) substantially equal to but less than the separation between the inner surfaces of said arms (332a, 332b), and having a thickness in a direction parallel to the shortest distance between adjacent ones of the strengthening ribs (338) substantially equal to but less than a separation between the adjacent ones of the strengthening ribs (338).
6. A clamping mechanism according to any one of the preceding claims, wherein the bolt (300) comprises an end stop (337) on an inner surface of the cross piece (336), the end stop (337) being arranged to abut a front surface (227) of the clamp plate (200) before the arms (332a, 332b) of the bolt (300) come into contact with a rear surface (41) of the cap (40), as the nut (100) is screwed on to the bolt (300).
7. A clamping mechanism according to any one of the preceding claims, wherein the clamp plate (200) and the cap (40) are rigidly connectable to each other on opposing sides of the nut (100) by a snap-fit mechanism (44a, 44b; 223a, 223b) of the clamp plate (200) and the cap (40) contained within the bore (112) of the nut (100).
8. A clamping mechanism according to any one of the preceding claims, wherein: the elongate main body (225) of the clamp plate (200) has a plurality of resilient arms (222a, 222b) projecting perpendicularly from a rear surface (226) thereof, each of said arms having a respective radially outwardly projecting tang (224a, 224b) formed thereon; a separation of the tangs (224a, 224b) from each other being such that if the arms (222a, 222b) are inserted into the bore (112) of the nut (100) in a first axial direction (z), the tangs (224a, 224b) come into contact with the screw thread (114) in the bore (112), whereby the screw thread (114) can push on the tangs (224a, 224b) causing the arms (222a, 222b) to flex radially inwardly towards each other; a distance of the tangs (224a, 224b) from the rear surface (226) of the clamp plate (200) being greater than an axial depth of the screw thread (114), such that if the arms (222a, 222b) are inserted into the bore (112) of the nut (100) in the first axial direction (z), the tangs (224a, 224b) can pass completely through the screw thread (114) and engage with an outer face of a final turn of the screw thread (114), causing the arms (222a, 222b) to spring back into their unflexed condition.
9. A clamping mechanism according to claim 8, wherein: the cap (40) has a plurality of resilient arms (42a, 42b) projecting perpendicularly from a rear surface (41) thereof, each of said arms having a respective radially outwardly projecting tang (44a, 44b) formed thereon; the clamp plate (200) having a plurality of apertures (223a, 223b) each for receiving a respective one of the tangs (44a, 44b) on the arms (42a, 42b) of the cap (40); a separation of the tangs (44a, 44b) on the cap arms (42a, 42b) from each other being greater than a separation of the corresponding apertures (223a, 223b) in the clamp plate (200) from each other, such that if the cap arms (42a, 42b) are inserted into the bore (112) of the nut (100) in a second axial direction (z') opposite to the first axial direction, the tangs (44a, 44b) on the cap arms (42a, 42b) come into contact with the arms (222a, 222b) on the clamp plate (200), whereby the arms (222a, 222b) on the clamp plate can push on the tangs (44a, 44b) of the cap arms (42a, 42b), causing the cap arms (42a, 42b) to flex radially inwardly towards each other; a distance of the tangs (44a, 44b) on the cap arms (42a, 42b) from the rear surface (41) of the cap (40) being greater than a distance of the corresponding apertures (223a; 223b) in the clamp plate (200) from the tips of the arms (222a, 222b) on the clamp plate (200), such that if the cap arms (42a, 42b) are inserted into the bore (112) of the nut (100) in the second axial direction (z'), the tangs (44a, 44b) on the cap arms (42a, 42b) can engage with the corresponding apertures in the clamp plate (200), causing the cap arms (42a, 42b) to spring back into their unflexed condition; and wherein a distance of the rear surface (41) of the cap (40) from the rear surface (226) of the clamp plate (200) when the tangs (44a, 44b) on the cap arms (42a, 42b) are engaged with the corresponding apertures in the clamp plate (200) is greater than an axial depth of the nut (100).
10. A clamping mechanism according to any one of the preceding claims, wherein a front surface (43) of the cap (40) has indicia (50) thereon.
11. A method of manufacturing a clamping mechanism according to claim 10, the method comprising injection moulding the cap (40) using a mould tool comprising a first tool insert for forming the indicia (50) on the front surface (43) of the cap, wherein the first tool insert has a mould for forming first indicia thereon, and the first tool insert is interchangeable with a second tool insert having a mould for forming second, different indicia thereon.
12. A nut assembly having a longitudinal axis (z-z') and comprising: a nut (100) having an axial bore (112) with a concave screw thread (114) formed on an inner surface of said bore (112); a first co-operating component (200) having an elongate main body (225) wider than the bore (112) of the nut (100) in a first radial direction (x-x') and an axial portion (222a, 222b) insertable into the bore (112) of the nut (100) in a first axial direction (z); a second co-operating component (40) having a main body portion (45) wider radially than the bore (112) of the nut (100) and an axial portion (42a, 42b) insertable into the bore (112) of the nut (100) in a second axial direction (z') opposite to the first axial direction; the first and second co-operating components (40, 200) being rigidly connected with each other on axially opposing sides of the nut (100) by connecting the axial portion (222a, 222b) of the first co-operating component (200) with the axial portion (42a, 42b) of the second co-operating component (40) through the bore (112) of the nut (100); the concave screw thread (114) in the bore (112) of the nut (100) corresponding to a convex screw thread (334) formed on an outer surface of a pair of arms (332a, 332b), and the elongate main body (225) of the first co-operating component (200) being narrower than the separation between an inner surface of each of said arms (332a, 332b) in a second radial direction (y-y'), such that elongate main body (225) can be introduced between said arms (332a, 332b) and the concave screw thread (114) can be brought into contact with the convex screw thread (334); wherein a part (47; 229a, 229b) of the first and second co-operating components (40, 200) can be maintained in the same orientation by contact with said arms (332a, 332b) if the nut is rotated about the longitudinal axis (z-z'), whereby the nut (100) can be screwed onto said arms (332a, 332b) without changing the orientation of the main body portion (45) of the second co-operating component (40) relative to the arms is (332a, 332b).
13. A nut assembly according to claim 12, wherein the first and second co-operating components (40, 200) are rigidly connected with each other on opposing sides of the nut (100) by a snap-fit mechanism (44a, 44b; 223a, 223b) of the first and second cooperating components (40, 200) contained within the bore (112) of the nut (100).
14. A nut assembly according to claim 12 or claim 13, wherein: the first co-operating component comprises a clamp plate (200); the axial portion of the first co-operating component comprises a plurality of resilient arms (222a, 222b) projecting perpendicularly from a rear surface (226) of the clamp plate (200), each of said arms having a respective radially outwardly projecting tang (224a, 224b) formed thereon; a separation of the tangs (224a, 224b) from each other being such that if the arms (222a, 222b) are inserted into the bore (112) of the nut (100) in the first axial direction (z), the tangs (224a, 224b) come into contact with the screw thread (114) in the bore (112), whereby the screw thread (114) can push on the tangs (224a, 224b) causing the arms (222a, 222b) to flex radially inwardly towards each other; a distance of the tangs (224a, 224b) from the rear surface (226) of the clamp plate (200) being greater than an axial depth of the screw thread (114), such that if the arms (222a, 222b) are inserted into the bore (112) of the nut (100) in the first axial direction (z), the tangs (224a, 224b) can pass completely through the screw thread (114) and engage with an outer face of a final turn of the screw thread (114), causing the arms (222a, 222b) to spring back into their unflexed condition.
15. A nut assembly according to claim 14, wherein: the second co-operating component comprises a cap (40); the axial portion of the second co-operating component comprises a plurality of resilient arms (42a, 42b) projecting perpendicularly from a rear surface (41) of the cap (40), each of said arms having a respective radially outwardly projecting tang (44a, 44b) formed thereon; the clamp plate (200) has a plurality of apertures (223a, 223b) each for receiving a respective one of the tangs (44a, 44b) on the arms (42a, 42b) of the cap (40); a separation of the tangs (44a, 44b) on the cap arms (42a, 42b) from each other being greater than a separation of the corresponding apertures (223a, 223b) in the clamp plate (200) from each other, such that if the cap arms (42a, 42b) are inserted into the bore (112) of the nut (100) in the second axial direction (z'), the tangs (44a, 44b) on the cap arms (42a, 42b) come into contact with the arms (222a, 222b) on the clamp plate (200), whereby the arms (222a, 222b) on the clamp plate can push on the tangs (44a, 44b) of the cap arms (42a, 42b), causing the cap arms (42a, 42b) to flex radially inwardly towards each other; a distance of the tangs (44a, 44b) on the cap arms (42a, 42b) from the rear surface (41) of the cap (40) being greater than a distance of the corresponding apertures (223a, 223b) in the clamp plate (200) from the tips of the arms (222a, 222b) on the clamp plate (200), such that if the cap arms (42a, 42b) are inserted into the bore (112) of the nut (100) in the second axial direction (z'), the tangs (44a, 44b) on the cap arms (42a, 42b) can engage with the corresponding apertures in the clamp plate (200), causing the cap arms (42a, 42b) to spring back into their unflexed condition; and wherein a distance of the rear surface (41) of the cap (40) from the rear surface (226) of the clamp plate (200) when the tangs (44a, 44b) on the cap arms (42a, 42b) are engaged with the corresponding apertures in the clamp plate (200) is greater than an axial depth of the nut (100).
16. A nut assembly according to any one of claims 13 to 15, wherein a front surface (43) of the second co-operating component (40) has indicia (50) thereon.
17. A nut assembly according to any one of claims 13 to 16, wherein the part (47; 229a, 229b) of the first and second co-operating components (40, 200) comprises a block (47) of the second co-operating component (40) locatable between the arms (332a, 332b), the block (47) being narrower radially than the bore (112) of the nut (100) in the first radial direction (x-x') and having a width substantially equal to but less than a separation between an inner surface of each of the arms (332a, 332b) in the second radial direction (y-y'), whereby the block opposes flexure of the arms (332a, 332b) towards each other if the concave screw thread (114) in the bore (112) of the nut (100) is screwed on to the convex screw thread (334).
18. A nut assembly according to claim 17, wherein the block (47) comprises a strengthening rib (46) aligned substantially parallel with the second radial direction (y-Y).
19. A method of manufacturing a nut assembly according to any one of claims 16 to 18, the method comprising injection moulding the second co-operating component (40) using a mould tool comprising a first tool insert for forming the indicia (50) on the front surface (43) of the second co-operating component (40), wherein the first tool insert has a mould for forming first indicia thereon, and the first tool insert is interchangeable with a second tool insert having a mould for forming second, different indicia thereon.
20. A nut assembly according to any one of claims 13 to 19, wherein the part (47; 229a, 229b) of the first and second co-operating components (40, 200) comprises a part (229a, 229b) of the first co-operating component (200) which can engage with said arms (332a, 332b) to be axially guided thereby.
21. A clamping mechanism substantially as hereinbefore described with reference to Figs. 5 to 14.