GB2300236A

GB2300236A - Rotation-resisting bolt

Info

Publication number: GB2300236A
Application number: GB9508480A
Authority: GB
Inventors: Ian Gardner
Original assignee: PERMASTORE Ltd
Current assignee: PERMASTORE Ltd
Priority date: 1995-04-26
Filing date: 1995-04-26
Publication date: 1996-10-30
Anticipated expiration: 2015-04-26
Also published as: GB9508480D0; GB2300236B

Abstract

A bolt has a shank (3) with a non-threaded length (5) of generally elliptical cross-section which will cooperate with the aperture or apertures into which it is inserted, in order to prevent or minimise rotation of the bolt. This removes the need for the bolt to incorporate sharp projections for preventing rotation, such projections being liable to damage a brittle or soft coating on sheets which are being bolted together. The bolt is for bolting together sheets that form the wall of a storage tank for farm slurry or municipal or factory effluent.

Description

ROTATION-RESISTING BOLT The present invention relates to a bolt which resists rotation, an assembly comprising sheets which are bolted together by using one or more such bolts, and a tank having a wall incorporating such an assembly.

In a known storage tank, the generally cylindrical wall comprises a plurality of sheets which are bolted together. Overlapping edges of adjacent sheets have cylindrical holes drilled or punched through them and bolts are inserted through the aligned holes. Generally speaking, the bolts are inserted from the inside of the tank and the nuts and washers are attached from the outside of the tank. Each bolt comprises a domed head and a shank which extends from the head and starts with a non-threaded length of circular crosssection and leads into a threaded length of circular cross-section. When the bolt is inserted in the aligned holes, the non-threaded length resides in the holes and the threaded length projects through to the outside of the tank so that a nut and washer may be fitted.The circular holes of the sheets conform fairly closely to the circular profile of the non-threaded length of the bolt.

For a storage tank that is going to be used to store a liquid effluent, such as farm slurry or municipal or factory effluent, it is usual for each sheet to comprise a metal substrate whose faces are coated with a protective coating.

This coating may be glass-based, paint or epoxy-based and may be relatively soft or brittle. Because the bolts are inserted from the inside of the tank some means must be provided to prevent their rotation whilst the nuts and washers are being fitted. The usual practice is to provide each bolt with four nibs which look like ribs and extend between the head and the base of the shank. When the bolt is inserted into the appropriate aligned holes in the sheets, the nibs bite into the inwardly facing face of the inner sheet of the tank and, in so doing, may damage the brittle or soft coating of that face.

According to the present invention, there is provided a bolt comprising a shank having a first threaded length of circular cross-section and a second non-threaded length of generally elliptical cross-section.

If the bolt is inserted in a hole which has a cross-sectional profile such as to engage with the generally elliptical cross-section of the second nonthreaded length of the bolt, rotation of the bolt in the hole may be substantially prevented or limited to under one complete revolution. In this way, it is then possible to attach a nut to the bolt.

Usually, the first length of the shank is contiguous with the second length of the shank.

Usually, the bolt further comprises a head which is integral with the shank. Preferably, the head is contiguous with the second length of the shank.

Preferably, the diameter of the circular cross-section is substantially equal to the length of the minor axis of the generally elliptical cross-section.

If the circular diameter is "X", then, in relation to transverse shear forces applied to the second length of the bolt, the bolt has a bigger cross-section to resist the shear forces than a conventional bolt which has a circular diameter of "X" along the full length of the shank.

The present invention also includes an assembly comprising first and second sheets bolted together by one or more bolting systems, wherein: each bolting system comprises at least one nut and a bolt in accordance with the present invention, with the shank of the bolt projecting through respective aligned apertures of the first and second sheets, at least one of the aligned apertures having a non-circular cross-section so as to cooperate with the second length of the shank to prevent complete rotation of the bolt.

Whilst rotation of the bolt may be prevented or limited by having only one of the aligned apertures having a non-circular cross-section, it is preferable that both apertures have such a cross-section.

The non-circular cross-section could be a design such as would be formed by two ellipses whose major axes are transverse to each other, thereby giving a four-lobed design of cross-section. However, we prefer that the noncircular cross-section is generally elliptical. In this way, the apertures in the sheets may be made to conform closely to the generally elliptical cross-section of the second non-threaded length of the bolt.

The second length of the shank of the bolt will usually be greater than the local thickness of one of the sheets or, more preferably, substantially the same as the local thickness of both sheets.

If the sheet adjacent to the head of the bolt comprises a metal substrate and a brittle or soft surface coating which faces towards the head, it is preferable that the head and the adjacent part of the shank do not have projection(s), such as rotation-resisting nibs, which break the surface coating.

Usually, the sheets will be bolted together by a plurality of the bolting systems which are arranged along overlapping edges of the sheets.

The present invention also includes a tank, such as a storage tank, e.g.

one for storing liquid effluent, having a wall, part of which comprises an assembly in accordance with the present invention.

Usually, one of the sheets is an upper part of the tank wall and transfers at least part of its weight to the other sheet, which is a lower part of the tank wall, via the bolting system(s).

Usually, if there are a plurality of the bolting systems arranged along overlapping edges of the sheets, the bolting systems and overlapping edges form a generally horizontal seam. The bolt of each bolting system may be arranged so that the major axis of the generally elliptical cross-section of the second length of the shank is generally horizontal.

instead of being vertically adjacent, the first and second sheets could be horizontally adjacent. Usually, if there are plurality of the bolting systems arranged along overlapping edges of the sheets, the bolting systems and overlapping edges form a generally vertical seam which usually will, in use, be exposed to hoop loads. The bolt of each bolting system may be arranged so that the major axis of the generally elliptical cross-section of the second length of the shank is generally vertical, so as to maximise the resistance of the wall to hoop loads.

A non-limiting embodiment of the present invention will now be described with reference to the accompanying drawings in which: Fig. 1 is a side view of a bolt in accordance with the present invention, looking along the major axis of the elliptical cross-section of the shank; Fig. 2 is a side view of the bolt of Fig. 1, but differs from Fig. 1 by looking along the minor axis of the elliptical cross-section of the shank; Fig. 3 is an end view of the bolt of Fig. 1, looking onto the end of the shank; Fig. 4 is a cross-sectional view through an assembly in accordance with the present invention; and Fig. 5 is an elevational view of the sheets of the assembly of Fig. 4.

Referring to the bolt illustrated in Figs. 1 to 3, it may be seen that the bolt comprises a domed head 1 having a flat face 2 from which projects a shank 3. The shank 3 comprises a first threaded length 4 of circular crosssection at the free end of the shank 3. Located between, and contiguous with, the head 1 and the first threaded length 4 is a second non-threaded length 5 of the shank.

As may be seen most clearly in Figs. 2 and 3, the second length 5 has a generally elliptical cross-section. The diameter of the first length 4 is substantially equal to the length of the minor axis of the generally elliptical cross-section of the second length 5.

The bolt, with its elliptical second length 5, may be produced by hot forging or by cold forming in a bolt heading machine.

Figs. 4 and 5 illustrate an assembly which forms part of the wall of a storage tank. This storage tank may be of the type which is commonly seen on farms and in industry in general and is generally cylindrical, may have an open top and usually is used for storing liquid effluent or solids. The wall of the tank is formed from a plurality of sheets which are bolted together to form the overall cylindrical shape of the tank wall. A small part of the overall wall of the tank is shown in Figs. 4 and 5.

A first sheet 6 and a second sheet 7 overlap along their edges and, as may be seen in Fig. 5, which shows only the two sheets, the overlapping edges incorporate a plurality of aligned pairs of punched holes 8, 9 of generally elliptical shape. Although not shown in Figs. 4 and 5, each sheet 6, 7 comprises a metal substrate whose faces are coated with a glass coating which is designed to resist chemical attack but which is relatively brittle and therefore easily damaged.

From the inside of the tank, the shank 3 of a bolt as illustrated in Figs.

1 to 3 is inserted through a respective pair of aligned holes 8, 9 of the sheets 6, 7. The flat nature of the face 2 of the head 1 and the smooth nature of the adjacent part of the second length 5 of the shank 3 mean that no projections are present in the bolt that would cause damage to the brittle glass coating of the second sheet 7.

The second non-threaded length 5 of the shank 3 has approximately the same length as the local thickness of the sheets 6, 7 and its generally elliptical cross-section is closely surrounded by the elliptical holes 8, 9 so that rotation of the bolt in the holes 8, 9 is almost entirely prevented. It is therefore comparatively easy for the operative who is assembling the tank to fit a nut 10 and washer 11 to the threaded length 4 of the bolt in order to bolt together the sheets 6, 7.

After a bolt has been fitted in each pair of aligned holes 8, 9, the sheets 6, 7 are fully bolted together along their overlapping edges and a generally horizontal bolted seam is produced. Other horizontal bolted seams and bolted vertical seams are produced along all other horizontally overlapping sheet edges and vertically overlapping sheet edges so as to bolt together all of the sheets of the tank and thereby produce the generally cylindrical form of the tank wall.

Claims

1. A bolt comprising a shank having a first threaded length of circular cross-section and a second non-threaded length of generally elliptical crosssection.

2. A bolt according to claim 1, wherein the first length of the shank is contiguous with the second length of the shank.

3. A bolt according to claim 1 or 2, further comprising a head which is integral with the shank.

4. A bolt according to claim 3, where the head is contiguous with the second length of the shank.

5. A bolt according to claim 3 or 4, wherein the head is domed.

6. A bolt according to any one of claims 1 to 4, wherein the diameter of the circular cross-section is substantially equal to the length of the minor axis of the generally elliptical cross-section.

7. An assembly comprising first and second sheets bolted together by one or more bolting systems, wherein: each bolting system comprises at least one nut and a bolt according to any one of claims 1 to 6, with the shank of the bolt projecting through respective aligned apertures of the first and second sheets, at least one of the aligned apertures having a non-circular cross-section so as to cooperate with the second length of the shank to prevent complete rotation of the bolt.

8. An assembly according to claim 7, wherein each of the aligned apertures has a non-circular cross-section.

9. An assembly according to claim 7 or 8, wherein the non-circular crosssection is generally elliptical.

10. An assembly according to any one of claims 7 to 9, wherein the second length of the shank of the bolt is greater than the local thickness of one of the sheets.

11. An assembly according to any one of claims 7 to 9, wherein the second length of the shank of the bolt is substantially the same as the local thickness of both sheets.

12. An assembly according to any one of claims 7 to 11, wherein the bolt is in accordance with claim 3, 4 or 5, the sheet adjacent to the head comprises a metal substrate and a brittle or soft surface coating which faces towards the head, and the head and the adjacent part of the shank do not have projection(s) which break the surface coating.

13. An assembly according to claim 12, wherein the surface coating is a glass-based coating.

14. An assembly according to claim 12, wherein the surface coating is a paint or epoxy-based coating.

15. An assembly according to any one of claims 7 to 14, wherein the sheets are bolted together by a plurality of the bolting systems which are arranged along overlapping edges of the sheets.

16. A tank having a wall, part of which comprises an assembly according to any one of claims 7 to 15.

17. A tank according to claim 16, wherein one of the sheets is an upper part of the tank wall and transfers at least part of its weight to the other sheet, which is a lower part of the tank wall, via the bolting system(s).

18. A tank according to claim 17, wherein the assembly is according to claim 15 and the bolting systems and overlapping edges of the sheets form a generally horizontal seam.

19. A tank according to claim 18, wherein the bolt of each bolting system is arranged so that the major axis of the generally elliptical cross-section of the second length of the shank is generally horizontal.

20. A tank according to claim 16, wherein the first and second sheets are horizontally adjacent.

21. A tank according to claim 20, wherein the assembly is according to claim 15 and the bolting systems and overlapping edges of the sheets form a generally vertical seam.

22. A tank according to claim 21, wherein the bolt of each bolting system is arranged so that the major axis of the generally elliptical cross-section of the second length of the shank is generally vertical.

23. A tank according to any one of claims 16 to 22, wherein the assembly is according to claim 12, 13 or 14 and the surface coating faces inwards into the tank.

24. A bolt substantially as herein described with reference to, or with reference to and as illustrated in, Figures 1 to 3 of the accompanying drawings.

25. An assembly substantially as herein described with reference to, or with reference to and as illustrated in, Figure 4 of the accompanying drawings.