WO2002008617A1

WO2002008617A1 - Threaded fastener

Info

Publication number: WO2002008617A1
Application number: PCT/GB2001/003201
Authority: WO
Inventors: Gino Dominico Mario Ashley Di-Mola
Original assignee: Mola Bolt Company Limited
Priority date: 2000-07-22
Filing date: 2001-07-16
Publication date: 2002-01-31
Also published as: GB0017931D0; GB2361276B; GB2361276A; AU2001270844A1

Abstract

The invention relates to a threaded fastener for engagement with either the cylindrical screw thread of a threaded bore (40) or a threaded nut having a central axis. The threaded fastener includes a hollow sleeve (20) for concentric alignment with the cylindrical screw thread. The sleeve (20) has a plurality of segments (30) arranged in a discontinuous circular array at one end thereof. The plurality of segments (30) either converges towards the central axis or is capable of converging towards the central axis on insertion of the fastener into the bore (40) or nut. The threaded fastener also includes an activation means (10) to bring the segments substantially parallel to the central axis whereupon a first series of threads (32) provided on an outer surface remote from the central axis of one or more of said segments (30) align and engage with the cylindrical screw thread.

Description

TITLE Threaded Fastener

DESCRIPTION

Field of Invention

The invention relates to a threaded fastener for engagement with a uniform cylindrical screw thread. More particularly, the invention relates to a threaded fastener that is relatively quick and easy to locate alongside a uniform cylindrical screw thread such that its threads do not engage with those of the screw thread until the fastener is in a desired position.

Background Art

Conventional nuts and bolts are generally used in combination to secure or fasten structural elements together. A bolt generally has a relatively large head and, stemming from that head, a relatively long and thin solid cylinder. The solid cylinder is usually provided with a uniform screw thread on its outer surface extending along at least a portion of the cylinder's length. Quite often, the screw thread extends the entire length of the cylinder.

Once the structural elements are manoeuvred into the desired position, a common bore is machined through all of the structural elements. Occasionally, the structural elements are pre- machined so that all the operator must do to ensure that the desired position has been established is to align the common holes provided in the structural elements. The cylinder of the bolt is then inserted into and through the common bore such that the head of the bolt abuts the outer surface of one of the structural elements. At the opposite end of the bolt, a corresponding nut is introduced over the cylinder of the bolt and screwed along the threaded portion of the cylinder to tighten and fasten together the structural elements intermediate the head of the bolt and the nut.

It is not always necessary to use a nut in conjunction with a bolt. For example, if the bore provided in that structural element which is most remote from the head of the bolt is threaded to correspond with the threads on the cylinder of the bolt, then by screwing the bolt into that hole, such that the respective threads engage, the intermediate structural elements are fastened to the remote structural element. A significant problem associated with the prior art is the need to continuously rotate or screw the bolt with respect to the item with which it engages (whether a nut or a threaded bore) so as to achieve the desired distance therebetween. In some applications, there is a significant distance between the position on the bolt where its threads commence and the position thereon where the desired fastening takes place. Even though the thread extending along this "dead" axial distance plays no part in the final fastening engagement, the end user must, in any case, rotate the nut or bolt by an amount sufficient to traverse that "dead" section before the required fastening can take place. Accordingly, the fitting and removal of a bolt or nut can be a frustrating, monotonous and time consuming task.

Furthermore, if the threads on the bolt which extend along the "dead" axial distance are in anyway damaged or incomplete, then it is impossible to effect the required fastening since progression of the nut or threaded bore along the bolt will be halted by the damaged threads.

A traditional method to ensure that a tight fastening is established between the bolt, the intermediate elements and the restraining nut or threaded bore is to use a spanner to tighten the entire assembly. Occasionally, such bolts and nuts are used in confined locations where space is limited and accordingly the freedom of the end user to rotate a spanner is restricted. In some instances the user is limited to a quarter turn of the bolt/nut at a time and accordingly the user must re-set the spanner to its initial position after every quarter turn. This problem can be overcome to a certain extent by using a ratchet. However, the user is still required to screw the nut or bolt along the "dead" section as explained above.

Furthermore, when securing structural elements together by means of bolt, it is beneficial to lubricate the threads on the bolt so as to ensure (i) that removal at a later stage is relatively straightforward and (ii) that the threads do not corrode prematurely. If the user intends for the bolt to provide a permanent fastening, then the longevity of the fastening can be improved by surrounding the threads with a locking agent. With the prior art, the only means of introducing these substances is to either introduce them directly into the bore before inserting the bolt or to dip the threaded portion of the bolt into the substances before inserting it into the bore. Accordingly, with conventional bolts it is impossible to introduce lubricants or locking agents into the bore once the bolt has been screwed into it.

Accordingly, it is an objective of the present to reduce the problems discussed above by providing a threaded fastener which has threads that only engage with a co-axial cylindrical screw thread when the threaded fastener is in a desired position. Hence, prior to engagement, the fastener is free to move in the axial direction with respect to the cylindrical screw thread and thereby locating the fastener at the desired position becomes a much simpler and quicker task.

Summary of the Invention

The present invention provides a threaded fastener for engagement with a uniform cylindrical screw thread of a threaded bore or a threaded nut having a central axis, the threaded fastener includes: a hollow sleeve for concentric alignment with the cylindrical screw thread and having a plurality of segments arranged in a discontinuous circular array at one end thereof, the plurality of segments either converging towards the central axis or capable of converging towards the central axis on insertion of the fastener into the bore or nut; and an activation means to bring the segments substantially parallel to the central axis whereupon a first series of threads provided on an outer surface remote from the central axis of one or more of said segments align and engage with the cylindrical screw thread.

Brief Description of the Drawings

By way of example only, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, of which:

Figures la and lb are plan views of a hollow cylindrical sleeve and a spreader pin, respectively, both of these components together forming a quick locating bolt in accordance with a first embodiment of the invention;

Figures 2a and 2b illustrate the manner in which the quick locating bolt of Figs, la and lb is introduced and fastened to a corresponding bore, respectively;

Figure 3 is a plan view illustrating the means provided for releasably locking together the hollow cylindrical sleeve and spreader pin of the quick locating bolt of Figs, la and lb; Figure 4 is a plan view demonstrating how the quick locating bolt of Figs, la and lb is disengaged and removed from a corresponding bore;

Figures 5a and 5b are plan views of a hollow cylindrical sleeve and a spreader pin, respectively, both of these components together forming a quick locating bolt in accordance with a second embodiment of the invention;

Figure 6 is a plan view illustrating the quick locating bolt of Figs. 5a and 5b as fastened to a corresponding bore;

Figure 7 is a plan view of the components of a quick locating bolt in accordance with a third embodiment of the present invention;

Figure 8 is a plan view of the components of a quick locating bolt in accordance with a fourth embodiment of the present invention;

Figures 9a and 9b illustrate a quick locating bolt in accordance with a fifth embodiment of the present invention; and

Figures 10a and 10b illustrate a quick locating bolt in accordance with a sixth embodiment of the present invention.

Specific Description of the Preferred Embodiments

Figs, la and lb illustrate a hollow cylindrical sleeve 20 and a corresponding spreader pin 10 which, in combination, form a quick locating bolt in accordance with a first embodiment of the present invention.

The spreader pin 10 comprises a standard hexagonal head 12 dimensioned for insertion into a conventional spanner or ratchet and a solid, thin, cylindrical body 16. As shown in the figure, the solid cylindrical body 16 extends from an underside face of the hexagonal head 12 which is also provided with four saw-tooth projections 14 (only one of which is shown). At some point along the length of the cylindrical body 16, a circumferential groove 18 is provided on its outer surface.

The hollow sleeve 20 comprises a flange 22, a barrel portion 26 and four threaded tangs 30 which are tapered in towards the central axis of the sleeve 20. The flange 22 is provided with four wedged cut-outs 24 which correspond with the four saw-tooth projections 14 provided on the hexagonal head 12 of the spreader pin 10. The internal diameters of the flange 22 and the barrel portion 26 of the hollow sleeve 20 are dimensioned so as to slideably accommodate the cylindrical body 16 of the spreader pin 10.

-The method by which the quick locating bolt is installed within a corresponding bore 40 will now be described with reference to Figs. 2a and 2b. Since the external diameter of the barrel portion 26 of the sleeve 20 has a smaller diameter than that of the bore 40 and the threaded tangs 30 are tapered inwards, the hollow sleeve 20 is freely inserted into the bore 40 until it is located a desired depth therein. Once at the desired location, the solid body 16 of the spreader pin 10 is inserted into the sleeve 20 until it abuts the internal surface of the threaded tangs 30. Then the hexagonal head 12 of the spreader pin 10 is struck by a hammer or such like instrument, as indicate by arrow F, until the saw-tooth projections 14 provided on the hexagonal head 12 are accommodated within the corresponding wedged cut-outs 24 provided on the flange 22 of the hollow sleeve 20. This action F forces the threaded tangs 30 outwards so that threads 32 formed on the external surface thereof engage with a threaded internal wall of the bore 40 thereby securing the quick locating bolt to the bore 40.

In order to tighten the arrangement, the hexagonal head 12 is turned clockwise in the conventional manner as illustrated by arrow C. Since the saw-tooth projections 14 on spreader pin 10 are interlocked with the wedged cut-outs 24 in the hollow sleeve 20, all components of the quick locating bolt rotate clockwise together and such rotation of the threaded tangs 30 urges the entire quick locating bolt further into the bore 40.

As illustrated in Fig. 3, in order to ensure that the spreader pin 10 does not inadvertently slide out of position within the hollow sleeve 20 after the quick locating¹ bolt has been secured and fastened to the bore 40 as aforementioned, a lip 28 is formed on the internal surface of each of the threaded tangs arid these lips 28 engage with the circumferential groove 18 on the external surface of the solid body 16 of the spreader pin 10 to releasably lock the spreader pin 10 to the hollow sleeve 20. Alternatively, the natural reactional force developed between the tangs 30 and the spreader pin 10 may be sufficient to ensure that the spreader pin 10 does not slide out of its secured position without the provision of the lips 28 and the corresponding groove 18. To remove- the quick locating bolt, the hexagonal head 12 of the spreader pin 10 is turned in the anticlockwise direction as illustrated by arrow A in Fig. 4. On anticlockwise rotation A of the hexagonal head 12, the saw-tooth projections 14 come out of engagement with the respective wedged cut-outs 24 on the flange 22 of the hollow sleeve 20, thereby forcing the spreading pin 10 and the hollow sleeve 20 apart and disengaging the lips 26 from the circumferential groove 18. Then, the solid body 16 of the spreader pin 10 can be retracted from the hollow sleeve 20 enabling the threaded tangs 30 to relax to their original inwardly tapered position. Thereby the user is permitted to remove the quick locating bolt quickly and easily.

After many uses, it is envisaged that the threaded tangs 30 may permanently deform so that they no longer relax to their original inwardly tapered position when the spreader pin 10 is withdrawn from the sleeve 20. This would not pose a serious problem since there would still be sufficient radial compressibility associated with the tangs 30 to enable the user to withdraw and insert the hollow sleeve 20 from and into the bore 40 without damaging the threads 32 on the tangs 30 or the corresponding thread of the bore 40.

Indeed, during development, the Applicant created a sleeve 20 on which the tangs 30 were not inwardly tapered but were substantially parallel to the central axis of the sleeve 20. In use, this did not cause damage to either the threads 32 on the tangs 30 or the corresponding thread of the bore 40 because the gap between neighbouring tangs 30 permitted the tangs 30 to move inwards relatively easily when the sleeve 20 was initially inserted into the bore 40. Hence, the present Application embraces the situation where the tangs 30 are parallel to the central axis of the sleeve 20 but are capable of slight radial compression when the sleeve 30 is initially inserted into the bore 40.

A further use of the quick locating bolt is in repairing damaged threads on the bore 40. The sleeve 20 can be inserted past the damaged thread of the bore 40 and secured to the bore 40 as previously mentioned by the insertion of the spreader pin 10. If the saw-tooth projections 14 on the spreader pin 10 and the wedged cut-outs 24 in the sleeve 20 are arranged with the opposite configuration to that previously described such to permit relative rotation therebetween in the clockwise (tightening) direction C but not in the anti-clockwise (loosening) direction A, then the entire quick locating bolt can be rotated in the anticlockwise direction A towards the damaged portion of the thread, and assuming that the threads 32 on the tangs 30 are of sufficient strength, further rotation would cause the quick locating bolt to move along the damaged portion, thereby reforming the thread on the bore 40 as it progresses. Since the quick locating bolt, in this situation, is anchored from within the bore 40 with respect to the damaged portion of the thread, it is believed that this method of repairing the damaged thread is less likely to produce cross-threading which is a feature of other common repair methods that approach the damaged thread from the other side of the bore 40.

Figs. 5a and 5b illustrate a hollow cylindrical sleeve 20 and a corresponding spreader pin 10 which, in combination, form a quick locating bolt in accordance with a second embodiment of the present invention. This embodiment differs from the previously described embodiment in that the releasable locking facility is provided by means of a circumferential lip 19 formed on the solid body 16 of the spreader pin 10 which engages circumferential grooves (not shown) provided on the internal surface of each of the threaded tangs 30.

Fig. 6 is a plan view illustrating the quick locating bolt of Figs. 5a and 5b with the spreader pin 10 fully inserted into the sleeve 20 to secure the quick locating bolt to a corresponding bore (not shown).

Fig. 7 illustrates a quick locating bolt in accordance with a third embodiment of the present invention. The difference between this embodiment and the previously described embodiments is that a relatively stiff wire retainer 34, such as a circlip, is provided in a recess 36 formed on the outer surface of each of the threaded tangs 30. The retainer 34 biases the threaded tangs inwardly such that when the spreader pin 10 is removed from the hollow sleeve 20, the threaded tangs 30 are urged into their initial inwardly tapered position.

Fig. 8 illustrates a quick locating bolt in accordance with a fourth embodiment of the present invention. In this embodiment, the spreader pin 10 is provided with a tapered head 13 and the flange 23 on the hollow sleeve 20 is hexagonal. Once the quick locating bolt has been located at the desired position within the bore 40 and the spreader pin 10 has been fully inserted as previously described, rather than tightening the arrangement by rotating the spreader pin 10 clockwise and thereby effecting rotation of the hollow sleeve 20 via the interlocking engagement of the saw-tooth projections 14 with the wedged cut-outs 24, the operator tightens the arrangement by toning the hexagonal flange 23 on the sleeve 20 directly with a spanner or ratchet.

Figs. 9a and 9b illustrate a quick locating bolt in accordance with a fifth embodiment of the present invention. In this embodiment the spreader pin 10' is significantly different to the spreader pin 10 of the previously described embodiments. The spreader pin 10' is housed within the hollow. cylindrical sleeve 20 at all times and is relatively thin so that it does not touch the barrel portion 26 of the sleeve 20. As shown in Fig. 9a at its upper end, the spreader pin 10' is pinned to an eccentric pivot point of an actuation lever 50 and at the lower end, it is provided with a solid conical member 52 which extends past the threaded tangs 30 of the hollow sleeve 20.

Once the quick locating bolt has been inserted to a desired depth within a corresponding bore, the bolt is secured as shown in Fig. 9b by flipping the actuation lever 50. Due to the pivoting of the spreader pin 10' about the eccentric pivot point of the actuation lever 50, this action draws the spreader pin 10' together with the solid conical member 52 into the sleeve 20, thereby gradually forcing the threaded tangs 30 outwards for engagement with the bore 40. As with the previous embodiment, the engagement between the bolt and the bore is tightened by turning the hexagonal flange 23 of the sleeve 20 clockwise with a spanner or similar tool.

To remove the bolt, the actuation lever 50 is returned to its original position as shown in Fig. 9a. By this action, the conical member 52 re-emerges from the sleeve 20 and the threaded tangs 30 are permitted to return to their inwardly tapered position.

A further embodiment of the invention is illustrated in Figs. 10a and 10b. Here the hexagonal flange 23 of the sleeve 20 is provided with a handle 60 and instead of a lever, the spreader pin 10' is provided with a plunger 66. A leaf spring 62 is positioned between the handle 60 and the plunger 66 and biases the plunger 66 away from the handle 60. As shown in Fig. 10b, to fasten this bolt to a corresponding bore 40 the barrel portion 26 of the sleeve 20 is introduced into the bore 40 and the user grips the handle 60 and the plunger 66 against the bias of the spring 62 thereby causing the conical member 52 to be withdrawn into the sleeve 20 and forcing the threaded tangs 30 outwards. This quick locating bolt is particularly useful for lifting or pulling components which have a threaded bore, the threads 32 provided on the tangs 30 selectively engaging the thread of the bore 40.

Claims

1. A threaded fastener for engagement with a uniform cylindrical screw thread of a threaded bore (40) or a threaded nut having a central axis, CHARACTERISED IN THAT the threaded fastener includes: a hollow sleeve (20) for concentric alignment with the cylindrical screw thread and having a plurality of segments (30) arranged in a discontinuous circular array at one end thereof, the plurality of segments (30) either converging towards the central axis or capable of converging towards the central axis on insertion of the fastener into the bore (40) or nut; and an activation means (10) to bring the segments (30) substantially parallel to the central axis whereupon a first series of threads (32) provided on an outer surface remote from the central axis of one or more of said segments (30) align and engage with the cylindrical screw thread.

2. A threaded fastener according to claim 1, wherein the activation means (10) is a spreader pin which is receivable within the hollow sleeve (20) to slideably engage with an inner surface of each segment (30).

3. A threaded fastener according to claim 2, wherein the hollow sleeve (20) is provided with a flange (22;23) at the end thereof which is remote from the plurality of segments (30).

4. A threaded fastener according to claim 3, wherein the spreader pin (10) comprises a head (12;13) and a solid cylindrical body (16), the head (12;13) abutting the flange (22;23) of the hollow sleeve (20) when the solid cylindrical body (16) has been inserted into the hollow sleeve (20) by an amount sufficient to bring the segments (30) substantially parallel to the central axis thereby securing the fastener to the bore (40) or the nut.

5. A threaded fastener according to claim 4, wherein the head (12) of the spreader pin (10) is hexagonally-shaped for use with a conventional spanner or ratchet and is provided with a plurality of projections (14) for engagement with a corresponding plurality of wedged cut-outs (24) provided on the flange (22) of the hollow sleeve (20) when the head (12) and flange (22) are in abutment, this engagement permitting relative rotation between the head (12) and the sleeve (20) in one direction (A) and preventing relative rotation in an opposite direction (C).

6. A threaded fastener according to claim 4, wherein the head (13) of the spreader pin (10) is tapered and the flange (23) of the hollow sleeve is hexagonally-shaped for use with a conventional spanner or ratchet.

7. A threaded fastener according to any of claims 4 to 6 further including a releasable locking means (18,28;19) provided between the solid cylindrical body (16) of the spreader pin (10) and the hollow sleeve (20) to ensure that the spreader pin (10) does not inadvertently slide out of position once it has brought the segments (30) substantially parallel to the central axis.

8. A threaded fastener according to any of claims 4 to 6, wherein a reactional force is developed between the solid cylindrical body (16) of the spreader pin (10) and the segments (30) when the spreader pin (10) has brought the segments (30) substantially parallel to the central axis and this reactional force is sufficient to ensure that the spreader pin (10) does not inadvertently slide out of position.

9. A threaded fastener according to claim 3, wherein the spreader pin (10') comprises a thin rod connected at one end to the vertex of a solid conical member (52) and connected at the other end to a withdrawal means which, when activated, draws the solid conical member (52) into the hollow sleeve (20) and thereby brings the segments (30) substantially parallel to the central axis.

10. A threaded fastener according to claim 9, wherein the withdrawal means includes an actuation lever (50) engaging with the flange (23) of the hollow sleeve (20), the actuation lever (50) having an eccentric pivot point about which the thin rod is pivoted such that when the actuation lever (50) is actuated, the solid conical member (52) is drawn into the hollow sleeve (20).

11. A threaded fastener according to claim 9, wherein a fixed handle (60) is provided on the flange (23) of the hollow sleeve (20) and the withdrawal means is a plunger (66) positioned intermediate the fixed handle (60) and the flange (23) such that when the plunger (66) is drawn towards the fixed handle (60), the solid conical member (52) is drawn into the hollow sleeve (20).

12. A threaded fastener according to claim 11 further comprising a spring (62) between the plunger (66) and the fixed handle (60) to bias the plunger (66) away from the fixed handle (60).