GB2244318A

GB2244318A - Screw-threadable nuts and bolts

Info

Publication number: GB2244318A
Application number: GB9111445A
Authority: GB
Inventors: Denis Eagles
Original assignee: GLO FLO PRODUCTS
Current assignee: GLO FLO PRODUCTS
Priority date: 1990-05-25
Filing date: 1991-05-28
Publication date: 1991-11-27
Anticipated expiration: 2011-05-28
Also published as: GB9111445D0; IE901885A1; GB2244318B; CA2043264A1

Abstract

A plastics nut 1 (Figure 1) or a plastics bolt 50 (Figure 10) has a number of unthreaded axial ribs 7 or 56 in which screwthreads can be formed when the nut 1 or bolt 50 is screwed onto or into a threaded bolt or threaded nut. Each nut 1 or bolt 50 thus can be used on one of a range of bolts or nuts having different thread types. A number of nuts may be formed integrally with a carrier strip. <IMAGE>

Description

SELF THREADING FASTENERS This invention relates to self threading fasteners and in particular to a self threading nut and a self threading bolt.

Nuts and bolts are produced with many different types of thread form, for example metric, BSF, BSW and so on. When carrying out maintenance work on machinery nuts and bolts are often damaged or lost. A considerable amount of time may be wasted in looking for a replacement if one is not readily available. A large amount of spares would be required to cover fasteners having all the different types of thread forms. To a relatively inexperienced person, for example, someone who might be carrying out DIY repairs, many different thread forms can look alike. The person may not be able to tell what type of replacement is required and have to purchase a selection of different types of nut or bolt and fit the replacement on a trial and error basis. Further, if a nut and bolt having dissimilar thread forms are screwed together the threads can be easily damaged or stripped.

The present invention is directed towards overcoming these problems.

According to the invention there is provided a fastener element forming one of the male and female parts of a threaded assembly, in which the other part is pre-threaded, wherein the fastener element has on it's surface deformable projections in which threads can be formed by engagement of the fastener element with the pre-threaded other part.

Preferably, the deformable projections comprise a number of spaced-apart ribs. Ideally the ribs extend axially along the surface of the fastener element.

In a particularly preferred embodiment, each rib has a tapered engagement end. The engagement end may be spaced-apart from one end of the fastener element.

In another embodiment, each rib is of generally triangular cross-section. Preferably, an outer free edge of each rib is rounded. In an alternative arrangement, each rib is of frusto-conical cross-section.

In a particularly preferred embodiment, the fastener element is a nut having a body with a cylindrical bore, the projections extending outwardly of a surface of the bore.

In another embodiment, the nut has an engagement end and a free end with a transverse screwdriver-receiving slot provided at the free end.

In a further embodiment, the fastener element is a bolt having a cylindrical shank, the projections extending outwardly of a surface of the shank.

In another aspect, the invention provides a kit comprising a number of the fastener elements frangibly attached to a plastics carrier frame. In some cases two or more different sizes of fastener element may be provided on the carrier frame.

The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a nut according to the invention, Fig. 2 is a plan view of the nut, Fig. 3 is a cross-sectional view of the nut taken along the line III-III of Fig. 2, Fig. 4 is a detail cross-sectional view taken along the line IV-IV of Fig 3, Fig. 5 is a detail cross-sectional view of the nut, shown in use engaging portion of a bolt, Fig. 6 is another cross-sectional view showing the nut in use engaged with a bolt, Fig. 7 is a perspective view of a number of the nuts mounted on a support frame, Fig. 8 is a plan view similar to Fig. 2 of a nut according to another embodiment of the invention, Fig. 9 is a cross-sectional view of the nut of Fig. 8 taken along the line IX-IX of Fig. 8, Fig. 10 ls a perspective view of a bolt according to another embodiment of the invention, Fig. 11 is a cross-sectional view of the bolt taken along the line XI-XI of Fig. 10, Fig. 12 is a side partially sectioned view showing the bolt in use engaged with a nut, Fig. 13 is a view similar to Fig. 9 of another fastener element, and Fig. 14 is a cross-sectional view taken along the line XIV-XIV of Fig. 13.

Referring to the drawings, and initially to Figs. 1 to 6 thereof, there is illustrated a plastics nut according to the invention indicated generally by the reference numeral 1. The nut 1 has a nut body 2 with six hexagonally arranged outer side faces 3. A generally cylindrical bore 5 extends through the nut body 2. A sidewall 6 of the bore 5 has a number of spaced-apart deformable elongate radial ribs 7. Each rib 7 extends axially along the sidewall 6 from an engagement end 9 of the bore 5 at a lower end 10 of the nut body 2 and terminates adjacent a free end 11 of the bore 5 at a top 12 of the nut body 2. It will be noted that a lower engagement end 15 of each rib adjacent the engagement end 9 of the bore 5 is tapered such that the height of the rib 7 reduces towards the engagement end 9 of the bore 5.Each rib 7 has a generally triangular cross-section with an outer free edge 18 of the rib 7 being rounded (See Fig. 4). A transverse screwdriver-receiving slot 19 is formed at the top 12 of the nut body 2.

Figs. 5 and 6 show the nut 1 in use engaged with a bolt 20 having a threaded shank 21 and head 22. The nut 1 and bolt 20 are shown in Fig. 6 clamping a pair of flanges 25 together.

In use, the nut 1 is screwed onto the bolt 20 and as the nut 1 engages the bolt 20 the threaded shank 21 of the bolt 20 forms a thread in the ribs 7 of the nut 1 corresponding to the thread on the shank 21 of the bolt 20. The engagement end 9 of the bore 5 is offered up to a free end of the shank 21 and it will be noted that the tapered lower ends 15 of the ribs 7 facilitate guiding the nut 1 into correct alignment with the bolt 20 and also facilitate easy initial thread cutting in the ribs 7. The nut 1 can be fastened either by means of a spanner which engages the sidewalls 3 of the nut body 2 or alternatively a screwdriver can be engaged with the slot 19 at the top 12 of the nut 1 to rotate the nut 1 relative to the bolt 20.

It will be appreciated that the diameter of the bore 5 and the height of the ribs 7 may be provided in any suitable dimensions to suit different bolt sizes and thread depths.

The nuts 1 may be used either as temporary or permanent fasteners. Each different size of nut can be used on a range of bolts having different thread types of similar general dimension, for example 6mm, h" BSF, i" BSW. The nut can even be screwed onto a bolt having damaged threads. A further advantage of the plastics nut is that it does not rust and needs no lubricant. The nut also has a locking effect as the ribs tightly engage the threads on the bolt.

Advantageously, the ribs are of generally triangular crosssection with the outer free edge 18 of each rib 7 being rounded. This configuration gives a good gripping action between the nut and the bolt and also the rounded edges 18 ensure that the ribs 7 do not jam in the root of the threads on the bolt. It will also be appreciated that the nuts are particularly useful for electrical applications as they are non-conductive.

Fig. 7 shows a number of the nuts 1 in various different sizes, each nut 1 attached by a breakable tab 30 to a-carrier frame 31. This conveniently allows the correct size of nut for a particularly application to be quickly selected, and also keeps the spare nuts 1 tidy during storage.

Referring now to Figs. 8 and 9, there is illustrated another plastics nut 40 which is generally similar to the nut described previously with reference to Figs. 1 to 6 and like parts are assigned the same reference numerals. In this case, it will be noted that lower ends 15 of the ribs 7 are spacedapart from the engagement end 9 of the nut 40, a cylindrical lead-in portion 41 being provided between the lower ends 15 of the ribs and the engagement end 9 of the nut 40. This leadin portion 41 further facilitates correct alignment of the nut 40 with a bolt onto which it is screwed to cut threads in the ribs 7.

Referring now to Figs. 10 to 12 there is illustrated a self threading bolt according to another embodiment of the invention indicated generally by the reference numeral 50.

The bolt 50 has an elongate shank portion 51 with a flanged head 52 at one end. An outer sidewall 55 of the shank portion 51 has a number of spaced-apart substantially parallel elongate ribs 56 which project radially outwardly of the sidewall 55 and extend between the head 52 and the free end 59 of the shank portion 51. A lower end 60 of each rib 56 is tapered such that the height of each rib 60 reduces towards the free end 59 of the shank portion 51.

Fig. 12 shows the bolt 50 in use engaging with a nut 65 to clamp a pair of flanges 66 together. As the nut 65 is screwed onto the shank portion 51 it forms a thread in the ribs 56 corresponding to the thread on the nut 65.

A number of bolts of different sizes may be mounted on a carrier frame in similar fashion to the nuts shown in Fig. 7.

Referring now to Figs. 13 and 14 there is illustrated another nut 70 according to another embodiment of the invention. The nut 70 is largely similar to the nut described previously with reference to Figs. 8 and 9 and like parts are assigned the same reference numerals. In this case the nut body 2 is of metal and the ribs 7 are formed in dove-tailed slots 71 in the sidewall 6 of the bore 5.

It is envisaged that in some cases deformable projections other than ribs may be provided in any suitable formation.

It will also be appreciated that the self threading fastener means may be incorporated in a piece of apparatus or machinery, forming holes or studs having a deformable engagement portion, particularly where the piece of apparatus or machinery is of plastics material.

The self threading fastener means according to the invention is preferably of plastics material, however, any other suitable materials may be used.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail.

Claims

1. A fastener element forming one of the male and female parts of a threaded assembly, in which the other part is pre-threaded, wherein the fastener element has on its surface deformable projections in which threads can be formed by engagement of the fastener element with the pre-threaded other part.

2. A fastener element as claimed in claim 1, wherein the deformable projections comprise a number of spaced-apart ribs.

3. A fastener element as claimed in claim 2 wherein the ribs extend axially along the surface of the fastener element.

4. A fastener element as claimed in claim 2 or claim 3, wherein each rib has a tapered engagement end.

5. A fastener element as claimed in claim 4 wherein the tapered engagement end is spaced-apart from an end of the fastener element.

6. A fastener element as claimed in any of claims 2 to 5 wherein each rib is of generally triangular cross section.

7. A fastener element as claimed in claim 6 wherein an outer free edge of each rib is rounded.

8. A fastener element as claimed in any of claims 2 to 5 wherein each rib is of frusto-conical cross-section.

9. A fastener element as claimed in any preceding claim wherein the fastener element is a nut having a body with a cylindrical bore, the projections extending outwardly of a surface of the bore.

10. A fastener element as claimed in claim 9 wherein the nut has an engagement end and a free end with a transverse screwdriver-receiving slot provided at the free end.

11. A fastener element as claimed in any of claims 1 to 8 wherein the fastener element is a bolt having a cylindrical shank, the projections extending outwardly of a surface of the shank.

12. A fastener element substantially as hereinbefore described with reference to Figs. 1 to 6 of the accompanying drawings.

13. A fastener element substantially as hereinbefore described with reference to Figs. 8 and 9 of the accompanying drawings.

14. A fastener element substantially as hereinbefore described with reference to Figs. 10 to 12 of the accompanying drawings.

15. A fastener element substantially as hereinbefore described with reference to Figs. 13 and 14 of the accompanying drawings.

16. A kit comprising a number of the fastener elements as claimed in any preceding claim frangibly attached to a plastics carrier frame.

17. A kit as claimed in claim 16 wherein two or more different sizes of fastener elements are provided on the carrier frame.

18. A kit substantially as hereinbefore described with reference to Fig. 7 of the drawings.