GB2174431A

GB2174431A - Non-circular tubular fencing post

Info

Publication number: GB2174431A
Application number: GB08606971A
Authority: GB
Inventors: Torsten Erlandsson
Original assignee: Gunnebo AB
Current assignee: Gunnebo AB
Priority date: 1985-04-30
Filing date: 1986-03-20
Publication date: 1986-11-05
Also published as: GB8606971D0; SE8502100L; NO861147L; DK125586A; SE8502100D0; SE462173B; DE3609601A1; FI861214A; FR2581115A1; DK125586D0; FI861214A0

Abstract

The post profile is composed of four similar parts, each having a shape defined by the portion of the curve in the upper left quadrant of Fig. 4. Axial flanges 9, 10, 11, 12 may extend inwards from each corner. The post has uniform flexural rigidity in all directions. <IMAGE>

Description

SPECIFICATION Tubular post The present invention relates to a tubular post, intended preferably as a fence post. Tubular posts may have circular or rectangular cross section. The great advantage with posts having circular cross section is that they have the same flexural resistance in all dirsctions.

This is not the case with a post having rectangular cross section, which is a considerable drawback since posts having rectangular cross section are in many respects more practical than posts with circular cross section.

The object of the present invention is to produce a post with polygon cross section, preferably rectangular cross section, said post being so constructed as to have substantially uniform flexural resistance, approximately equivalent to the flexural resistance for posts having circular cross section. According to the invention, this is achieved by calculating the peripheral shape of the post profile with the aid of the curve

and/or providing the post with thicker parts protruding from the inner tube surface along the periphery, preferably in the form of flanges.

The flanges may be located between the side edges in a part side of the inner tube surface or they may be located directly at the side edges.

Each side may be provided with one or more thicker parts or flanges.

The presence of thicker parts and preferably flanges produces reinforcement enabling the wall thickness to be reduced in comparison with tubes having circular or rectangular cross section.

Since the post profile is in the form of a polygon, the number of part-surfaces in the surface of the post is increased, thus reducing the tendency to buckle.

Tubes according to the invention can be manufactured by means of extrusion or hotmoulding blanks not provided with flanges.

The tubes may also be produced from strip metal which is shaped in a tube-moulding works.

When manufacturing posts from a strip of metal the flanges take the form of folds. A fold should be formed in such a way that its opening end becomes sealed due to the stresses in the formed metal. Suitable materials for posts are metal, plastic and other mouldable material.

Further characteristics of the present invention are revealed in the following claims.

The invention will be described in more detail with reference to the accompanying drawings in which Figures 1-3 show three different tube profiles, Figure 4 shows a curve for calculating a suitable non-circular profile, and Figures 5-12 show four additional embodiments of the tube profile.

Fig. 1 shows a tube obtained by bending a strip of metal in a tube-moulding machine. The tube may be rectangular with flattened or bevelled corners, its cross section thus forming an octogon, The tube thus consists of the four sides 1, 2, 3 and 4 and of the sides 6, 7, 8 and 9 formed by the flattened or bevelled corners. To produce a tube the metal strip is provided with a fold 5. Flanges 10, 11, 12 and 13 protrude inwardly from sides 6, 7, 8 and 9. These flanges are obtained by folding the metal. This is performed so that the pockets formed are completely closed, this being effected by stresses in the metal sealing the openings of the pockets to prevent unnecessary material from arriving in the pockets. Each pocket may form an angle with the tangent at the point of departure. This angle may vary between 0 and 90 .

The height of each flange should be less than or equal to its mean radius to the centre of the profile times (c1-e "2) to ensure that the increase in material weight is not greater than the increase in the least flexural resistance.

The tube shown, with rectangular cross section, may of course also be provided with several inwardly directed flanges arranged on sides 1, 2, 3 and 4. -Flanges may also be located in the corners.

The tube show may of course be shaped having so many sides that its cross section resembles a polygon approaching a circle.

The advantage of a post having a cross section of the type just described is that, in comparison with a conventional post with circular cross section, the post with polygon cross section and inwardly directed flanges can be made with less wall thickness without losing anything in flexural rigidity or buckling resistance, and increasing this in relation to the weight of the profile per running meter.

On the sides with large surfaces such as 1 and 3, for instance, the tube according to Fig.

1 may be provided with longitudinal, inwardly directed channel-like grooves in order to reduce buckling tendencies.

Fig. 2 shows a tube for a post the same as that shown in Fig. 1 except that the fold is of a different type. The fold here has been formed producing a guide groove or attachment channel. The groove may be used to secure the ends of the fencing, for instance.

The attachment channel eliminates the need for drilling, punching or riveting to attach the fencing, and thus also eliminates any passages which might permit moisture to reach the inside of the post. The designations in the present figure are identical to those in Fig. 1, with the exception that they have been provided with prim signs.

Fig. 3 shows a tube profile substantially identical to that of Fig. 1. For this reason the parts agreeing with those in Fig. 1 have been given the same designations, but with biss signs. It can be seen that the short sides of the tube profile have been provided with longitudinal indentations having the appearance of longitudinal ridges seen from the inside. These have been designated 16 and 19. The long sides of the profile, on the other hand, have each been provided with two longitudinal indentations, designated 17, 18 and 14, 15.

As is apparent from the above, the present invention has enabled better flexural resistance along the periphery of tubes having rectangular cross section and enables a reduction in wall thickness in tubes with circular cross section, without loss of flexural rigidity or buckling resistance, and increasing this in relation to the weight of the profile per running meter.

According to Fig. 4 a profile can be achieved offering improved flexural resistance along the periphery of a post with non-circular profile cross section if the equation

is used and drawn in a coordinate system as shown in the figure. It is thus the curve portion in the second quadrant which is used.

This indicates the advantageous cross section for one quarter of the cross section of the post. A suitable cross section is shown in broken lines. This cross section offers better buckling resistance than a cross section exactly following the curve portion in the fourth quadrant.

For posts with non-circular cross section, but preferably quadratic cross section, substantially uniform flexural resistance is obtained along the entire periphery either if the profile is selected using the curve in Fig. 4 or by the use of thickened wall sections or flanges in accordance with Figs. 1-3. However, it should be obvious that a combination of both these methods is feasible.

Figs. 5 and 6 show a fourth embodiment of a tube profile in which the four corner flanges, corresponding to the corner flanges 10, 11, 12 and 13, are more open and the vertical sides 1 and 3 have been provided with reinforcements 18 and 19, the reinforcement 18 being in the form of a longitudinal indentation while the reinforcement 19 consists of a double-fold corresponding to the fold 5 in Fig. 1.

Figs. 7 and 8 show a fifth embodiment of the tube profile and differ from that in Figs. 5 and 6 in that two additional reinforcements 20, 21 and 22, 23 have been applied on each vertical side. These reinforcements are similar to reinforcement 18.

The tube profile shown in Figs. 9 and 10 differs from that in Figs. 7 and 8 in that the indentation 18' is missing.

The profile according to Figs. 11 and 12 differ from that in Figs. 9 and 10 only in that the corners have been provided with bevels 24, 25, 26 and 27. In other words the profile has acquired the appearance of octogon.

Claims

1. A tubular post having the profile of a polygon, intended preferably as a fence post, characterised in that the profile is composed of four similar parts, each part preferably consisting of three parts with two corners and where the shape of the circumference of each part is determined by the part of the curve

which is located in the other quadrant in the curve pertaining to the coordinate system.

2. A tubular post according to claim 1, characterised in that a number of axial flanges (10-13) protrude from the inner surface of the tubular post, along its periphery, each axial flange forming an angle with the tangent at its starting point and preferably being determined at the periphery of the post by the curve part in the fourth quadrant.

3. A tubular post according to claim 2, characterised in that said angle is between 0" and 90".

4. A tubular post according to claim 2, characterised in that the height of each flange (10-13) is dependent on a factor, Il-e 1/2, which is based on the distance of the outer and inner edges of the flange (13) to the centre of the profile.

5. A tubular post according to claim 2, characterised in that the number of flanges (10-13) is such, and their location along the periphery, that the flexural rigidity of the post is as uniform as possible along the periphery.

6. A tubular post according to one or more of the preceding claims, characterised in that on one side (9) in the inner surface of the post a flange (13) is located, preferably equidistant between, the side edges of said side.

7. A tubular post according to claim 6, characterised in that more than one flange (13) protrudes from one side (9).

8. A tubular post according to one or more of the preceding claims, characterised in that a flange (13) protrudes from a side edge to a side (9) of the post.

9. A tubular post according to one or more of the preceding claims, characterised in that the polygon profile resembles a circle.

10. A tubular post according to one or more of the preceding claims, characterised in that the polygon profile (1-4) resembles a rectangle.

11. A tubular post according to claim 10, characterised in that one or more of the corners (6-9) is/are obtuse-angled.

12. A tubular post according to one or more of the preceding claims, characterised in that each flange (13) constitutes a fold in the surface material of the post, said fold preferably being compressed at its opening edge.

13. A tubular post according to one or more of the preceding claims, characterised in that it has a longitudinal fold (5) in the form of a guide, attachment channel or groove, or the like.

14. A tubular post according to one or more of the preceding claims, characterised in that one or more of the flanges (10-13) are replaced by thicker parts which may either be applied or constitute a part of the walls.

15. A tubular post according to one or more of the preceding claims, characterised in that the side of the post surface is provided with one or more inwardly facing axial ridges (14-18).

16. A tubular post according to one or more of the preceding claims, characterised in that the post consists of extruded material such as metal, plastic or some other mouldable material.

17. A tubular post according to one or more of the preceding claims, characterised in that the post consists of a strip of metal shaped, for instance, in a tube moulding works.

18. Tubular post according to one or more of the preceding claims, characterised in that the post is produced by hot-rolling a tube blank.

19. A tubular post substantially as hereinbefore described with reference to the accompanying drawings.