GB2142369A

GB2142369A - Protective grating

Info

Publication number: GB2142369A
Application number: GB08317854A
Authority: GB
Inventors: Bo Johansson
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-06-30
Filing date: 1983-06-30
Publication date: 1985-01-16
Also published as: FI842623A; NO156383C; GB8317854D0; SE8403340D0; DE3423629A1; SE8403340L; SE454904B; NO156383B; NO842557L; FI842623A0

Abstract

A protective grid or grating 1 comprises an external tubular frame 5 with horizontal and vertical tubular cross-members 3, 4 positioned in separate adjoining planes. The cross-members are a welded at all crossing points and to the frame 5. The frame 5 has holes on the inside and on the outside at the junction with each cross- member for the insertion of hardened steel rods. The steel rods are freely rotatable and extend right across the grating from one edge to the other. <IMAGE>

Description

SPECIFICATION Protective grating The present invention relates to a protective grille or grating of the kind comprising tubular guides, housings, or casings, extending both in a horizontal direction and in a vertical direction and connected to an external or surrounding tubular frame, each said tubular casing containing a freely rotatable hardened steel rod. The invention also relates to a method of making such a protective grille or grating.

It is already known to use hard steel rods or wires enclosed in tubular casings to make burglarproof gratings. However, these previously known protective arrangements are complicated and expensive to manufacture. - They also incorporate weak construction details, and for this reason it is not possible to take full advantage of the steel rods enclosed in the tubular casings.

United States Patent Specification No. 679 028 describes a window grating comprising conventional horizontal bars and vertical tube casings enclosing hard steel rods. The rods are mounted in ball bearing seats in each end of the tube casings. The ball bearing seats seal the ends of the tube casings and thus protect the bars from corrosion. The intention with this bearing-mounted rod is that the rod should rotate when attacked with a hack saw or file, and thus should be impossible to cut through. However, this protective grating has several disadvantages. It is not possible to joint the vertical and horizontal bars by welding, because the welding would not softanneal the hard steel rod and make it easy to cut through.If the horizontal and vertical bars are not jointed together, it is possible to deflect or distort a tube casing such that it will prevent the internal rod from rotating, and make it possible to cut the rod with a file or hack saw. Another disadvantage is that when a tubular bar is attacked with a file or hack saw, metal cuttings will fall down into the ball bearing. The metal cuttings may then jam the bearing balls and thus prevent the inner rod from rotating and make it susceptible to attack.

Another previously known protective grating comprises a window frame and glazing bars made of rectangular tube sections. The glazing bars in one direction extend from one side of the window to the other and each glazing bar contains a round hardened steel bar which extends into the window frame at both ends.

The glazing bars in the other direction extend in the same plane as the first-mentioned glazing bars. They extend from one full length bar to the next and their ends are attached to the full length glazing bars, suitably by welding.

The short glazing bars enclose round hard steel rods. These steel rods are turned to a smaller section at their ends and these smaller end sections are seated freely rotatable in holes in the full length glazing bars. This arrangement can also be used as a protective grating with its bars parallel to the glazing bars of an adjoining window.

This previously known protective grating arrangement has several disadvantages. The hardened inner rods only extend the full length from side to side of a window in one direction, which weakens the grating considerably. Another serious disadvantage is that when the rectangular tube sections are joined together by welding any hardened steel rod inside would be soft-annealed and lose its resistance to attack by metal-cutting tools.

Thus the benefits of having a freely-rotating hardened steel rod enclosed in a tubular casing are lost.

United States Patent Specification No. 2 103 130 described a safety grating made of round tubes connected by four-way threaded pipe couplings. The ends of the horizontal and vertical bars are embedded or otherwise secured in the walls of a building. Located in the horizontally and vertically arranged bars are metallic cables constructed of a plurality of twisted metallic strands. The ends of the cables are anchored in the ends of the tubular casings and the remaining portions of the cables are free with a certain amount of slack.

Being free, the cables can move when attacked with a hack saw, and therefore are very difficult to cut. Furthermore, if an initial cut is made, the cable is expected to pinch or grip the hack saw blade and thus prevent further cutting. However, this protective grating has several imperfections. The thickness of the cables can only be half the inside diameter since they cross one another at each intersection. Because pliable cables are used, it is only necessary to cut each cable at one point. Since each cable is made of several strands which in turn are made of twisted individual wires, it is possible to separate the strands from each other and cut each individual strand or wire with diagonal pliers or similar tools.Obviously this protective grating will not provide a protection in proportion to its dimensions and would give less protection than a grating made of massive bars of the same size.

An object of the present invention is to provide a protective grille or grating comprising hardened steel rods enclosed in tubular casings, which is of a robust design, without any weak construction details, with the tube casings joined to each other at their intersection points, and in which the hardened steel rods are not weakened by heating during the manufacture, each rod extending from one side to the other of the protective grating and the inside of each tube casing being fully utilized by the enclosed steel rod, the tube casings containing no loose parts which might jam and lock the enclosed steel rod.

With this object in view, the present invention provides a protective grating comprising tubular casings extending in a horizontal direction and in a vertical direction and connected to an external or surrounding tubular frame each said tubular casing containing a freely rotatable hardened steel rod characterised in that each said rod extends from one side of the protective grating to the other end at least the rods extending in one direction reach from a point inside one external tubular frame member to a point inside an opposite tubular frame member, and that the tubular casings extending in one direction are situated in a different adjoining plane to those extending in a divergent direction, the tubular casings being welded to each other at their crossing points and joined to the tubular frame members at their ends, said external tubular frame being provided with holes 17 for the hardened steel rods at connecting points to the tubular casings and an insertion hole at the outside of the frame at each tubular casing for the insertion of a hardened steel rod.

A further object of the invention is to provide a method of making such a protective grating.

Persuant hereto the invention provides a method of making a grating as aforesaid characterised in that the tubular casings and the members of the tubular frame are cut to size and drilled, these parts placed in position with the horizontally extending and the vertically extending tubular casings placed in separate adjoining planes, the parts being welded together at the crossing points between the tubular casings at the connections between the tubular casings and the frame and at the corners of the frame the protective grid or grating being stress-relieving heat treated and surface treated, if necessary, and the hardened steel rods inserted in the tubular casings after the heating operations are completed.

The invention will be described further, by way of example, with reference to the accompanying drawings in which:~ Figure 1 is a diagrammatic elevation illustrating a practical embodiment of the protective grating of the invention;~ Figure 2 is an enlarged part-sectionai detail of the portion indicated at II in Fig. 1, to show the form of the tubular casings and enclosed rods;~ Figure 3 is an enlarged sectional detail taken along the line Ill-Ill of Fig. 1; Figure 4 is an enlarged sectional detail taken along the line IV-IV of Fig.Figure 5 is an enlarged sectional detail taken along the line V-V of Fig. 1, and also showing the door frame; Figure 6 is an enlarged sectional detail taken along the line VI-VI of Fig. 1 and through a lock arranged in the grate door; and Figure 7 is an enlarged fragmentary section taken as indicated by the line VII-VII of Fig.

1.

Fig. 1 shows a protective grille or grating according to the invention used as a protective door 1. The door 1 comprises a plurality of tubular casings 2 of which those extending in the horizontal direction have been indicated by the numeral 3 and those extending in the vertical direction have been indicated by the numeral 4. The ends of the tubular casings 2 are joined to an external tubular welded frame 5. The tubular casings 2 extending in the one direction are situated in a slightly offset and adjoining plane relative to those extending in the other direction, and the tubular casings 2 are welded to each other at each crossing point 6. The grate door 1 is mounted in a door frame 7 by hinges 8 in a jamb 9. The door 1 is securable with a handle-operated latch 10 and two key-operated locks 11 on opposite jamb 12.The door frame 7 is mounted by bolts 13 in the adjacent wall or in the frame to an adjoining ordinary door (not shown) in such a way that the bolts 13 are not accessible for removal.

Fig. 2 shows in detail how the horizontal tube casings 3 and the vertical tube casings 4 are arranged in two separate adjoining planes.

At each crossing point 6, the tube casings 3, 4 are connected by welded joints 14. In each tube casing 2 there is a hardened steel rod 15 or the like. These steel rods 15 all reach from one side to the other of the protective grating 1, and extend into the external tubular frame 5 as can be seen in the detail of Figs. 3 to 7.

Fig. 3 shows how each tubular casing 2 is mounted with its end 16 inserted into a hole 17 in the frame 5 and fastened by a weld 18.

The inserted end 16 gives increased stability to the frame 5 and the tubular grating, and facilitates manufacture the protective grating.

Fig. 4 shows one of the tubular casings 2 connected to the frame 5 and how the frame 5 is provided with an insertion hole 19 for introduction of the respective hardened steel rod 15. The size of the hole 19 is suitably between the size of the rod 15 and the internal size of the tube casing 2. In this way the rod 15 will catch on the edge 20 of the hole 19 and is not so easy to remove. The removal of the rods 15 is made even more difficult if the rod 15 is given a very slight bend before hardening and tempering. The hole 19 is suitably blanked off by a plastic cap 21.

Fig. 5 shows how the protective grating is mounted by means of hinges 8 in the door frame 7. The jamb 9 of the door frame 7 is made of a composite folded and bent steel profile. It is provided with through holes 22 for the mounting bolts 13. The grate door is provided with a rod 15 having an extension 23 which lodges in a seat 24 in the jamb 9.

The rod 15 is joined to the frame 5 by a welding bead 25. The application of a welding bead 25 will not impair the hardness of the rod 15, since it requires only a short and localized heating for the welding operation.

The extension 23 prevents the door 1 from being opened by driving out pintles 26 from the hinges 8. At least one, and suitably three, of the rods 15 should have such an extension.

Fig. 6 shows a combined handle and keyoperated latch and lock device 27 mounted in a casing 28, which constitutes a part of the outside frame 5. The casing 28 includes a square tubular piece 29 connected to one of the tubular casings 2 with its hardened steel rod 15. The lock device 27 has one handleoperated bevelled lock bar 30 and a keyoperated flat lock bar 31. The lock bars lodge into seats 32 in the jamb 12. The jamb 12 is made of a composite steel profile in the same way as the jamb 9.

Fig. 7 shows two alternative ways of mounting the vertically-extending tube casings 4. For comparatively light duty the lower end of each vertical tube casing 4 is welded to a flat iron bar 3 33 welded to lower member 34 of the tubular frame. At the other end, the tubular casings are welded to the side of a top member 35 of the tubular frame. The rods 15 are prevented from being removed downwards by a flat iron or plate 33, the lower member 34 and a threshold 36. The threshold is made of a flat iron bar and is a part of the door frame. Upwards, the rods 15 are prevented from being removed by top piece 37 of the door frame and further by the wall and eventually by the ceiling of the room. The top piece 37 is made of a composite steel profile of the same design as the side jamb 5.

The lower member 34 and the top member 35 contain respective hardened steel rods 15 in the same way as the tubular casings 2. In the frame 5 it is possible to use a coarser dimension of the steel rod than in the casings 2.

For heavy duties, where this way of mounting the tubular casings 2 is not considered to be sufficient, they may be connected in the same way as is described above in connection with Figs. 3 and 4. This is shown by broken lines in Fig. 7 where a rectangular tubular bottom frame member 34' and top frame member 35' can be seen. The rod 15 is inserted through a hole 20' closed by a plug 21'. Correspondingly a wider threshold 36' and top piece 37' are used. The use of a rectangular section tube material in the vertical frame members makes it easier to introduce reiriforcing rods also into the vertical frame members. In addition, the vertical frame members are protected by the door frame which, at least partially, may be made of hardened steel.

The door frame can be mounted on the inside of an ordinary door frame, without diminishing the size of the door opening.

The door frame may, of course, be of any suitable section, for instance a Z-profile section, which follows the inner profile of the ordinary door frame.

Care should be taken, when making a protective grating according to the invention, not to weaken the strength of the reinforcing steel rods. To achieve this, preferably the tubular frame is first drilled and cut to size, and then the horizontal and vertical tubular casings are placed in position with the frame members, and the grating is welded together. Hinges, enclosures for locks and other appliances are then welded on. If necessary a stress-relieving heat treatment is performed.

Any surface treatment and preferably also painting is then effected. As the last operational step door locks are fitted and the reinforcing steel rods are introduced into the tubular casings and the insertion holes are closed with their plastics caps. This operational sequence prevents the reinforcing rods from being subjected to heat and thus losing their strength. The reinforcing rods are suitably hardened and tempered to a hardness of 42-48 H.R.C. As described above, the rods may, be given a slight bend to keep them in place in the tubular casings before hardening.

The frame and tubular casings for the protective grating are preferably made of a comparatively soft steel material. In this way one achieves a structure which is tough and tenacious and which will not easily break up at the welding joints.

The mesh size of the protective grating should preferably not be greater than 200 x 300 mm. A preferred size for the reinforcement rods is 10 mm diameter., with the rods being inserted through respective holes about 11 mm in a tubular casing with 13 mm internal size. Other sizes of reinforcement rods. Depending on the circumstances for instance in the diameter range from 5 to 25 mm, may be used.

The protective gratings according to the invention can be used for instance as safety doors in dwellings, offices and commercial premises to hinder or prevent illegal entry to a locale or a part of a locale. The invention can also be used as protective gratings for windows in the same locales as well as in kiosks, news stalls and box offices, for instance for the sale of tickets.

The invention is not limited to the embodiments described and illustrated in drawings, but can be varied without departing from the scope of the invention defined by the following claims.

The steel rods 15 should occupy more than half the minimum inside dimension of the tubular casings 2 and are preferably introduced from the hinge side of a door and from above.

Claims

1. A protective grid or grating comprising tubular casings extending in a horizontal direction and in a vertical direction and connected to an external or surrounding tubular frame each said tubular casing containing a freely rotatable hardened steel rod characterised in that each said rod extends from one side of the protective grating to the other and at least the rods extending in one direction reach from a point inside one external tubular frame member to a point inside an opposite tubular frame member, and that the tubular casings extending in one direction are situated in a different adjoining plane to those extending in a divergent direction, the tubular casings being welded to each other at their crossing points and joined to the tubular frame members at their ends, said external tubular frame being provided with holes 17 for the hardened steel rods at connecting points to the tubular casings and an insertion hole at the outside of the frame at each tubular casing for the insertion of a hardened steel rod.

2. A protective grid or grating as claimed in claim 1, characterised in that the ends of the tubular casings extend through the holes 17 into the interior of the tubular frame members.

3. A protective grid or grating as claimed in claim 1 or 2, characterised in that at least one and preferably three of the horizontal rods are each provided with an extension at the hinge side adapted to be introduced in a seat in a door jamb to prevent the door from being opened if the pintles are removed from the hinges.

4. A protective grid or grating as claimed in claim 1; 2 or 3, characterised in that each rod is provided with a slight bend, such that the ends of the rods are off-set from the insertion holes in the frame, after the rods have been inserted through said holes into their tubular casings.

5. A protective grid or grating as claimed in any preceding claim characterised in that the tubular casings and the external tubular frame are made of a soft material, such as mild steel, welded at all the crossing points between the horizontal and vertical tubular casings, and that the tubular frame is welded in the corners and to the ends of the tubular casings.

6. A protective grid or grating as claimed in any preceding claim characterised in that the rods are made of hardened and tempered steel, preferably with a hardness of 42-48 H.R.C.

7. A protective grid or grating as claimed in any preceding claim characterised in that all the hardened steel rods extend from a point inside an external tubular frame member to a point inside an opposite external tubular frame member.

8. A method of making a protective grid or grating as defined in any of the claims 1 to 6, characterised in that the tubular casings and the members of the tubular frame are cut to size and drilled, these parts placed in position with the horizontally extending and the vertically extending tubular casings placed in separate adjoining planes, the parts being welded together at the crossing points between the tubular casings at the connections between the tubular casings and the frame and at the corners of the frame the protective grid or grating being stress-relieving heat treated and surface treated, if necessary, and the hardened steel rods inserted in the tubular casings after the heating operations are completed.

9. A method of making a protective grid or grating as claimed in claim 8 characterised in that at least one casing for a locking device is welded to the external frame to constitute a part thereof, and that hinges are welded to the frame before the insertion of the hardened steel rods.

10. A method of making a protective grid or grating as claimed in claim 9 characterised in that at least one and preferably three horizontal hardened rods are made with an extension protruding outside the insertion hole and are fastened to the tubular frame by a welding bead.

11. A protective grid or grating substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

12. A method making a protective grid or grating substantially as hereinbefore described with reference to the accompanying drawings.