EP0304267A1

EP0304267A1 - Security members and method of making same

Info

Publication number: EP0304267A1
Application number: EP88307576A
Authority: EP
Inventors: Frederick Gerald Forfitt
Original assignee: DIRECTNEXT Ltd
Current assignee: DIRECTNEXT Ltd
Priority date: 1987-08-19
Filing date: 1988-08-16
Publication date: 1989-02-22
Also published as: GB8719600D0

Abstract

A method of making a security member (10) for use as a bar in a barrier comprises forming a structural member (20) with slot means (12, 14, 16), locating cutting resistant material (18) in the slot, and fixing same in position. The step of forming the structural member with the slot means is performed by fabricating or shaping one or more structural elements (20), such as flat strip plates or elements, to define the slot means (12, 14, 16) between co-operating surfaces thereof, such as their side edges.

Description

This invention relates to security members, and to a method of making same. An example of a security member to which the invention relates is a bar for a security barrier. The invention is also applicable to other security members and structures employing same.
In the case of security members in the form of bars for use in barriers, there are several technical requirements. First, there is the need for the bars or the like to be resistant to the action of cutting tools such as hacksaws and the more recently available rod saws which are encrusted with tungsten carbide and are capable of cutting almost any but the very hardest of materials. Also, there is a need for these bars or the like to have sufficient resistance to deflection to be able to withstand the application of considerable bending loads by unauthorised persons using devices such as improvised screw jacks inserted between the bars.
To resist the cutting action of rod saws or the like, previously proposed security members have tungsten carbide embedded therein. The tungsten carbide takes the form of small cylindrical pellets or rods incorporated into machined slots at high risk positions of the bar sections, such as corners. After this, these slots are covered and the carbide fixed in position in various ways, such as by providing an exterior sleeve-like member.
However, the drawback of this previously proposed method is that it can only conveniently be applied to standard steel sections such as rounds, flats, squares or hollow metal structural sections. Furthermore, the machining process is a relatively expensive procedure.
Accordingly, we have identified a requirement for an improved method of making security members, together with security members themselves in which one or more of the above-identified disadvantages of the prior art is mitigated or overcome.
According to the invention there is provided a method of making a security member together with a security member made by such method and a security member per se, as defined in the accompanying claims.
The invention may be applied to security structures and security members generally.
In a preferred embodiment, a security member comprises a hollow section structural member. The structural member may have a regular or irregular polygonal or a curved or round cross-sectional shape. One preferred such shape is triangular. However, quadrilaterals are also very suitable, whether regular or otherwise. Where the security member is to be employed in a situation requiring relatively high strength, one or more core structural members is preferably employed. The core structural member may have projecting elements extending lengthwise thereof, so that the core has a generally spider-type cross-sectional shape. At one or more corners of the structural member there are provided slot means. The slot means are defined by lengthwise-extending plate-type members together with the core and/or the ends of the spider-type arms of the core structural member. In the slot means there is located tungsten carbide in rod or pellet form, or any other suitable material which is resistant to cutting, for example molybdenum carbide. The structural member of the security member may be formed by welding or brazing, or any other convenient metal fabricating technique. The cutting resistant material may be located at only one or more corners if desired, and may be secured in position by welding or bonding. Where a structural core is provided, the tungsten carbide or the like is preferably provided at those corners of the polygon where the core is also attached. In the embodiment, the core structure is welded lengthwise to the hollow internal structure of the structural member , whereby a composite structure is obtained having significantly greater strength than a simple hollow structure,this being due to transfer of loads between the core and the hollow external structure. The core structure is of a brazable or weldable, or fusion weldable material, this enabling simple construction of the slot means to receive the tungsten carbide or the like.
Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which Figs 1 to 21 show cross-sections through 21 embodiments of the invention having differing structures, which will be individually described.
As shown in Fig 1, a security member 10 has a cross-sectional shape corresponding to that of an equilateral triangle and has three slot means 12,14,16 defining locations for cutting resistent material such as rods of tungsten carbide 18. These rods are located within the slot means by a welding operation and resist cutting of the security member by rod saws and the like.
Security member 10 comprises three structural elements 20 which form the individual sides of the triangle seen in Fig 1. These structural elements are in the form of strip elements extending lengthwise of the security member, and the side edges of the strip elements define between them the slot means 12,14 and 16.
Within the hollow structure formed by the strip elements 20, there is provided a structural core 22 comprising a circular section core tube 24, extending lengthwise of the security member, and three radially projecting elements 26,28 and 30 which extend into the corners of the triangular shape of the security member, and likewise extend lengthwise thereof. The projecting elements 26,28 and 30 co-operate with the strip elements 20, at each corner of the triangle, to define the slot means 12,14 and 16. The three elements of the structure at each corner are welded together in a continuous root welding operation prior to insertion of the tungsten carbide rods. These latter are likewise secured in place by a further continuous welding operation similar to that employed in the prior art procedures.
In Fig 1, and in the other figures, the material of the welds has not been shown. The projecting elements 26,28 and 30 are welded to the core tube 24 in a similar continuous way, and indeed, all welding operations in the fabrication of the structural member 10 are carried out on a continuous basis which permits great efficiency of production.
The embodiment of Fig 2 corresponds with that of Fig 1 except that the core structural element 24 of Fig 1 is in the form of a solid rod instead of a hollow tube. The solid rod is identified by reference numeral 40. Other parts of the structure correspond to those of Fig 1.
In the embodiment of Fig 3, the structure otherwise corresponds to that of Fig 1, but in place of the round-section tubular core there is provided a triangular section core 50 formed by shaping a suitable mild steel plate in a press brake. The adjacent edges 52 of the core are welded together, and at each corner of the core there is provided a projecting element 54,56,58 corresponding to the elements 26,28 and 30 in Fig 1.
In Fig 4, the embodiment of Fig 2 is modified by the use of solid- section rods 60,62,64 in place of the projecting elements 26,28 and 30 of Fig 1, and for the same purpose.
In the embodiment of Fig 5, the embodiment of Fig 4 is modified by the use of circular section tubes 70,72,74 and 76 in place of the solid section rods 60,62,64 and 40 of Fig 4, and for the same purpose, and in the same manner.
Turning now to the embodiment of Fig 6, it will be seen that in section the security member 80 is a regular quadrilateral polygon having strip form structural elements 82, a circular section tubular core 84 and radially projecting elements 86. These latter, with the structural elements 82 serve to define the slot means 88 at each corner. The structural elements 82 are tangential to the core tube 84, and the general structure and arrangement, and the method of construction, correspond, apart from these differences, with that of Fig 1.
In the embodiment of Fig 7 there is a notable difference from the preceding embodiments in that the core 90 itself is close enough to the corners of the structure so that the definition of the slot means 92 does not require any projecting element. The strip-form structural elements 94 are plug welded at 96 to the core 90, at intervals along the length of the security member.
In the embodiment of Fig 8, the core 100 has projecting elements 102 located mid-way between the edges of its sides. The projecting elements co-operate in defining the slot means 104 as in other embodiments.
Fig 9 shows a further square-section security member 110. In this case, the slot means 112 at each corner is defined by adjacent edges of the strip-form structural elements 114, together with separate rod-form core members 116. These latter are welded in position at each corner. This arrangement is appropriate where less structural strength is needed than, for example, in the embodiment of Fig 1.
Fig 10 shows a security member 120 having an irregular polygonal cross-sectional shape and suitable for use as an end member in a security structure or grille, for abutting or forming part of the frame of such a grille.
The slot means 122 are defined at the four corners by the adjacent edges of the strip-form structural elements 124, together with the adjacent edges of an X-section core 126 which is itself formed as a fabrication from three strip elements 128,130,132.
In the embodiment of Fig 11, the structure corresponds closely with that of Fig 1, except that the strip-form structural elements 140 and 142 are of equal width to each other but of differing width to that of structural element 144, whereby the cross-sectional shape is that of an isosceles triangle rather than an equilateral triangle. Corresponding differences in width of the projecting elements 146,148, and 150 are of course provided. The security member is otherwise constructed and arranged as in Fig 1.
Fig 12 shows a further embodiment which bears the same relationship to Fig 2 as, approximately, the embodiment of Fig 11 does to Fig 1. In Fig 12, the security member 160 has a right-angle cross-sectional shape but is otherwise constructed as is the embodiment of Fig 2.
Fig 13 shows a circular-section embodiment in which arcuate section structural elements 170 are plug-welded at 172 at intervals along their lengths to a circular section tubular core 174. No projecting elements are required for defining the slot means 176.
The embodiment of Fig 14 corresponds to that of Fig 13 but employs a solid rod-form core 180.
The embodiments of Figs 15 and 16 employ hollow and solid-section oblong rectangular cores 190 and 192 respectively, having structural elements 194 plug-welded thereto at 196, and defining slot means 198 between their longitudinally extending side edges as in previous embodiments.
The embodiment of Fig 17 has a generally oblong rectangular structural member 200 with slot means 202,204 defined by the longitudinally-extending side edges of a press-brake-formed U-section 206 (constituting a structural element) and a complementary laminar structural element 208. Three rod elements 210,212,214 constitute core means, of which the elements 210 and 214 co-operate in defining the slot means 202,204.
The embodiments of Figs 18 and 19 have an irregular quadrilateral polygonal cross-sectional shape corresponding somewhat with that of Fig 10. The security member 220 of Fig 18 is otherwise constructed in a manner similar to the structural member 10 of Fig 1, having a round section tubular core, and the security member 230 of Fig 19 bears a similar relationship to the embodiment of Fig 2, having a solid rod-form core 232.
FIgs 20 and 21 correspond to Figs 19 and 18 respectively, being irregular quadrilaterals in cross-section and having solid and hollow cores respectively. However, whereas in Figs 18 and 19, the core structural members 234 and 236 are arranged as tangents to three of the strip elements 238, in Figs 20 and 21, the cores 240 and 250 are supported clear of the strip elements by their radially projecting elements 242 and 252 respectively. Otherwise, these embodiments are constructed in much the same way as the preceding embodiments, being formed by continuous welding techniques and with the cutting resistant materials located in the slot means by suitable welding or brazing techniques, and other constructional features as disclosed above. The cutting resistant materials are located in analogous positions to those shown in Fig 1.
Amongst other modifications which can be made in the above embodiments while remaining within the scope of the invention are the following :

1. Hollow or solid structures having any suitable regular or irregular polygonal shape.
2. The fabricated structural member may be spot welded or continuous welded or brazed. Where it is welded, the MIG process may be employed.
3. The thickness of the faces of the polygon may be varied according to need.
4. The cutting resistant materials may be in rod or pellet or other form.

Claims

1. A method of making a security member comprising forming a structural member with slot means defining a location for a cutting resistant material, locating said cutting resistant material therein and fixing same in position, characterised in that said step of forming said structural member with said slot means is performed by fabricating or shaping one or more structural elements to define said slot means between co-operating surfaces thereof.

2. A method according to claim 1 characterised in that said structural member comprises one or more strip elements extending lengthwise of said structural member and defining said slot means between adjacent edges thereof.

3. A method according to claim 2 characterised in that said strip elements define a hollow section.

4. A method according to claim 3 characterised in that said hollow section is in the form of a regular or irregular polygon in section, or has a continuous curved cross-section, e.g. a circle.

5. A method according to claim 4 characterised in that said polygon has one of said strip elements at each side thereof.

6. A method according to claim 4 characterised in that one of said strip elements forms more than one side of said structural member.

7. A method according to any one of the preceding claims characterised in that a lengthwise extending reinforcement core is located in said structural member.

8. A method according to claim 7 characterised in that said core co-operates with said structural elements to define said slot means.

9. A method according to claim 8 characterised in that said core comprises, in section, one or more projecting elements which co-operate with said structural elements in defining said slot means.

10. A method according to claim 9 characterised in that said core comprises a lengthwise extending core structural member having said projecting elements extending lengthwise thereof and projecting outwardly therefrom, said structural member of the security member being polygonal in section and said slot means being defined at one or more corners of said polygon, said one or more projecting elements of said core structural member projecting into one or more corners of said polygon to co-operate with said security member structural elements in defining said slot means.

11. A method according to claim 10 characterised in that said core structural member comprises a hollow section member.

12. A method according to claim 10 characterised in that said core structural member comprises a solid section member.

13. A method according to claim 11 or claim 12 characterised in that said core structural member is a regular or irregular polygon or is circular in cross-sectional shape.

14. A method according to any one of claims 11 to 13 characterised in that said hollow section member is of curved cross-sectional shape, said security member structural elements being arranged as tangents thereto in the section.

15. A security member comprising a structural member having slot means defining a location for a cutting resistant material, and having said cutting resistant material fixed therein, characterised in that said structural member is formed as a fabrication or pressing or the like formed from one or more structural elements which define said slot means between co-operating surfaces thereof.

16. A security member according to claim 15 characterised in that said structural member comprises one or more strip elements extending lengthwise of said structural member and defining said slot means between adjacent edges thereof.

17. A security member according to claim 16 characterised in that said strip elements define a hollow section.

18. A security member according to claim 17 characterised in that said hollow section is in the form of a regular or irregular polygon, or has a continuous curved cross-section.

19. A security member according to claim 18 characterised in that said polygon has one of said strip elements at each side thereof.

20. A security member according to claim 18 characterised in that one of said strip elements forms more than one side of said structural member.

21. A security member according to any one of claims 15 to 20 characterised in that a lengthwise-extending reinforcement core is located in said structural member.

22. A security member according to claim 21 characterised in that said core co-operates with said structural elements to define said slot means.

23. A security member according to claim 22 characterised in that said core comprises, in section, one or more projecting elements which co-operate with said structural elements in defining said slot means.

24. A security member according to claim 23 characterised in that said core comprises a lengthwise extending core structural member having said projecting elements extending lengthwise thereof and projecting outwardly therefrom, said structural member of the security member being polygonal in section and said slot means being defined at one or more corners of said polygon, said one or more projecting elements of said core structural member projecting into one or more corners of said polygon to cooperate with said security member structural elements in defining said slot means.

25. A security member according to claim 24 characterised in that said core structural member comprises a hollow section member.

26. A security member according to claim 24 characterised in that said core structural member comprises a solid section member.

27. A security member according to claim 25 or claim 26 characterised in that said core structural member comprises a regular or irregular polygon or a circular section member.

28. A security member according to any one of claims 25 to 27 characterised in that said hollow section member is of curved cross-sectional shape, said security member structural elements being arranged as tangents thereto in the section.