EP0453540A1 - Production line for burglarproof grilles and grilles manufactured on said production line - Google Patents

Abstract

An automatic production line of burglary-proof gratings composed of longitudinal sections or bars assembled by means of spreader bars or tie rods, intended to be mounted on lateral framing sections capable of being rolled up, d a type already available on the market, such as extruded aluminum sections, comprises a coil (10) of steel wire (1) having sufficient thickness and hardness, cold stretching pressure (15) of the wire (1) which stretches the wire (1) so as to produce a continuous length of straight and rigid material, a bending module (20) which pulls the wire (1) and gives it the desired wavy shape, a module annealing (25) of limited segments of the wire, a heating module (30) of the wire, a coating box (40) in which the hot wire is covered with nylon powder, a cooling module (50) of the wire to '' at an almost ambient temperature, a cutting module (60) of the wire at the points annealed according to d es predetermined dimensions, a trough (70) for collecting the cut lengths of the wire, in which the lengths of wire are oriented in the desired direction, and an assembly table (80) on which the individual lengths of wire are connected to tie rods (2) so as to produce the finished wire-proofing.

Description

PRODUCTION LINE FOR BURGLARPROOF GRILLES AND GRILLES MANUFACTURED ON SAID PRODUCTION LINE

This invention relates to a complete production line for burglarproof grilles, and a grille which acts as a physical barrier against possible intruders. This kind of grille is usually intended for mounting in front of, and sometimes behind, doors and windows in public buildings, assembly halls, shops, offices, factories, business premises or showrooms.

Existing grilles of this kind are chiefly made of sectional aluminium, aluminium tubing and aluminium rods with spacers or ties between the bars or rods. The material itself has significant advantages. Aluminium is relatively lightweight and durable. The aluminium sections can be purchased in ready-cut lengths with relatively low capital investment for the necessary equipment to manufacture the sections. It serves the purpose well and has a pleasant surface which is also suitable for anodizing in various colours.

Such grilles are manufactured by Companies like Alusol at Silkeborg in Denmark.

In the manufacturing process of ready-made grilles of a given width, there will be significant and costly wastage when the purchased lengths of aluminium sections or tubing have to be cut to size for the finished product. The Approval Committee for Norwegian Assurance Companies requires that the aluminium sections or tubing have a diameter of no less than 14 mm to prevent cutting through with ordinary shears or cutting tools. Grilles are therefore rather solidly built and will generally pre ent direct view to the inside. It will thus be pointless to display exhibits behind the grille. Certain types of grille have wires of spring steel which roll inside the aluminium sections when one attempts to saw through them. This increases the weight of the grille and renders it impractical, especially in large widths. The cost of material is affected and the production costs increase further, due to the additional time-consuming and mainly manual work required for assembling the various individual parts.

In addition, there exist burglarproof grilles made of curved or straight steel tubing, with ties between the tube lengths, similar to aluminium grilles. Here too, the tubing must have a diameter of at least 14 mm to prevent cutting. Sawing through this material is difficult enough, but the material has other drawbacks. Galvanized steel tubing will discolour rather rapidly; the material in itself is heavy; and because it is sold in pre-determined lengths, there will also be waste when cutting those lengths to the required size for the grille. In addition, the manufacturing process demands a series of individual manual operations.

The known rolling shutter grilles made of curved or straight tubing or of extruded sections with spacers or ties will thus generally present the same disadvantages or shortcomings. The objects of this invention are therefore to:

- manufacture a burglarproof grille with at least the same degree of safeguard against burglary as that obtained with existing grilles;

- manufacture a burglarproof grille which is perfectly acceptable aesthetically, with a pleasing surface and colour; - manufacture a burglarproof grille with large mesh to enable viewing of exhibits in a display window, or to give a better view to the inside or to the outside for any other purposes;

- manufacture a burglarproof grille out of cheaper raw materials than the materials used up to now: - manufacture a burglarproof grille with less waste than with earlier used methods, when trimming to size;

- manufacture a burglarproof grille with the help of an automated production line which is far more effective time-wise and production-wise than the production lines at present in use.

The objects of the invention are achieved with a production line for the manufacture of burglarproof grilles as disclosed in this invention, and with the grille also of this invention, both of which are characterized by the features which appear in the claims hereunder.

A detailed description of the invention is given below with reference to the accompanying drawings, where:

Figure 1 shows a front view of a portion of grille in accordance with this invention.

Figure 2 shows two alternative embodiments of the tie 2 on figure 1 ,

Figure 3^' shows a principle diagram of the production line according to this invention.

Figure 4 shows an enlarged detail of module 70 on figure 3, and Figure 5 shows the feeding method for the ties 2. The invention is based on the idea that, instead of using a material of such thickness that it cannot be cut through, one uses material whose hardness prevents such cutting. Sawing through the material is too time consuming. Tests have shown that two men equipped with an 18" long bolt cutter cannot cut through drawn, carbon-enriched, steel wire of spring steel quality or better, when the wire has a diameter of 6.5 mm or more. Moreover, such a wire is so stiff that, when taking into account the fact that the material cannot be cut through, it will not be necessary to have high strength requirements for the spacers or ties placed between each longitudinal wire of the grille. Practical tests have shown that if a hardened steel chain is embedded in every eighth plastic tie, the grille will be impenetrable.

Such steel wire is commonly available on the market in considerable lengths wound on spools or reels. Generally, 6.5 mm wire is sold in lengths of approximately 4000 m, and will suffice for approximately 1000 square meters of burglarproof grille. It is also a very low-cost material compared to alternative materials for grilles.

Experiments have been conducted where the steel wire was coated with a nylon coating of a quality similar to that used for racks and cutlery baskets for dishwashers. The experiments have shown that such nylon coatings can be coloured as required, and with very simple methods. The coating shows a considerable resistance to sunlight. The coating also shows a good resistance to the environment one finds at street level, such as salts and acids. In addition, the coating has a very satisfactory resistance to mechanical wear and tear. Metallic-coloured coatings, which harmonize with modern fa?ade material and with aluminium door and window frames, seem to be appropriate.

Figure 1 shows parts of two wire lengths 1 and 3. By cold drawing, the wire is given the characteristic wave shape as shown on the drawing. The wires 1 and 3 are linked with ties 2 at the point where the wires are closest to each other. At the points where the wires 1 and 3 are furthest apart from each other, they are, each independently of the other, linked with other wi_r___ not shown on the drawing. Two preferred embodiments of the ties 2 are illustrated in alternative 1 and alternative 2 on figure 2. The ties of both embodiments are made of a hard-wearing plastic, with a hardened steel reinforcement in every eighth tie. The use of plastic has several advantages. The ties are easy and cheap to manufacture in large quantities; they are well suited to the processes of an automated production line for grilles; and the material has only a minimum wear-and-tear effect on the nylon coating of the steel wire.

The result is a strong and environmentally neutral grille with good clearance for light. The grille is therefore perfectly suitable for display windows and the like. Naturally, the mesh size suggested on figure 1 may be varied. For rolling grilles, or when used in front of a window, for example, the ends of the steel wires are inserted into aluminium sections which may be of existing design. Various designs for such frames or sections can easily be ordered from manufacturers and do not constitute a part of this invention.

Figure 3 illustrates the schematic principle of the production line which is described in detail as follows. Reference point 10 symbolizes a spool or reel of spring steel wire. The wire 1 is drawn through a straightening press 15 which has horizontal and vertical rollers (a single set of rollers is shown on the figure). Although the wire will have acquired a curved shape when stored on the reel 10, cold drawing in the straightening press will result in a perfectly straight wire ready for the next steps in the production line. The next module 20 consists mainly of two shaping wheels which give to the straight wire the wave shape illustrated on figure 1. Great accuracy in reproduction of the individual bends or waves in the bending module is essential. With the use of stamping sheets mounted between the teeth of the bending wheels - these stamping sheets acting in a similar way as the die base of a die cutter - and by adjusting the pressure on the wire section, one reaches a force which is exactly sufficient to exceed the material's yield point. One thus achieves sufficient accuracy of reproduction of the bend so that trimming at a later stage of manufacture, and assembly of the ties on the wires at a further stage of manufacture may be 5 effected automatically to give an accurate, finished grille.

As illustrated in the schematic diagram, on figure 3, of the automatic production line of this invention, the bending module 20 delivers whole lengths of ready o shaped wire into a annealing module 25, and the wire is sent further to a heating module equipped with a heater 30. A propane burner or a similar type of equipment heats the segment of wire which passes through the heater to a temperature of 250 to 300 degrees Celsius. 5 The wire leaves the heater through a narrow slot. A roller is mounted close to the slot to provide support and assist in the further displacement of the wire down the production line.

Before reaching the heating module 30, the wire 0 has gone through the processes involved in the annealing module 25. In the annealing module, a measuring device to register the length of the wire is provided in the form of a pulse counter over a running wheel. Next comes a sliding plate mounted on a heating unit for annealing 5 two segments on each wire length. The next device is a new sliding plate mounted on a pneumatic cooling unit situated before the water-cooling unit.

The wire is annealed at the points where it will later be trimmed during the manufacturing process. The 0 wire is annealed on two short segments, usually of 2 cm length. On those segments, the wire is heated to a temperature of approximately 700 degrees Celsius. The annealing points are then air-cooled and subsequently water-cooled. 5 Module 40 is a coating box where the earlier mentioned nylon powder is sprayed on to the wire. The correct quantity of electrostatically charged powder is blown into the box and sticks electrostatically to the wire where it melts. Inside the following module 50, the temperature of the wire is brought down to near room temperature. In a preferred embodiment, this is effected with the help of water jets at a predetermined temperature and pressure. At the delivery end of the water-cooling module, support rollers are mounted to feed the wire to the next module.

At this stage in the production line, the spring steel wire is shaped, plastic-coated and runs in uncut lengths at room temperature. A counting and trimming module is schematically illustrated on figure 3 as reference point 60. Trimming of the wire is effected in this module by clamping the wire to a carriage. The wire is trimmed with flying shears and the carriage slides back. The lengths cut to size are placed in a predetermined direction in a collecting trough 70. The collecting trough has a feeding device controlled by pneumatic pistons 84 and 90 as shown on figures 4 and 5 in a preferred embodiment. Trimming of the wire is controlled by a PLC which keeps track of the annealing points, and counts down to zero starting from a number determined by a preset counter. Each time the countdown reaches zero and the wire lies in the correct direction, the wire is cut on the outside of each annealing point, and the wire is at the same time flattened on its upper and lower face, just inside the cutting edge, and on the annealed segment. These flats at the extremities of each wire length will be later used for fixing the grille to the side frames or aluminium sections which are not a part of this invention. Rationalized production with a minimum of trimming waste, and automation of the process are effected by inputing the physical dimensions of a given number of grilles to be produced into a programmable logic controller (PLC). The PLC memorizes the required length for each wire and the number of wires for each grille. It is also the PLC which starts and controls the whole production line.

The PLC starts first of all the heating module 30. After a while the rest of the line is switched on. This can of course be effected by sensing the temperature in the heating module. However, the stability of the equipment makes it possible to determine the necessary delay between starting the heating module and switching on the rest of the line.

When the module 30 is warm, the wire is fed to the bending module 20. In the initial phase, the machine rejects unusable material left over from the previous day's production. The new order of grilles is then effected as the correct number of wires of each length passes through the machine. When this is effected, this part of the production line is switched off until the next order is started.

For each grille, a number of wires of identical lengths, as delivered by the machine, hang next to each other in the collecting trough 70. Two grilles are separated by a simple dividing system.

Assembly of the grille starts when a length of wire hanging in the collecting trough 70 is dropped down into the feeding unit 82 of the assembly table 80 and is placed against the guide bar 86. A number of ties 2 await in the slots of the slide bars 88, as illustrated on figure 5. The correct positioning of the ties in the slide bars 88 is effected by pneumatic pistons 90, controlled by the PLC. When the ties are in place, the wire length is pushed forward by the piston 84. As the wire travels forward, the ties will move up and down the slide bars 88. The next length of wire drops down and is pushed forward when the next set of ties is in position in the slide bars 88. Every other length of wire is positioned on the table 82 with its first bend upward, while the lengths in between those are positioned with their first bends downward. Also, the first set of ties is positioned in the first, third, fifth, etc. slide bar, while the second set of ties is placed in the second, fourth, sixth, etc. slide bar.

As will be understood from this description, the production line of this invention permits the rational and time-saving manufacture of a product, while at the same time reducing material consumption. The grille is in itself a product which has clear advantages over existing burglarproof grilles, and it is considered an integral part of this invention.

The description and the accompanying drawings are meant to illustrate the idea behind the invention. The invention is in no way restricted to the preferred embodiment illustrated here, and other embodiments may be derived from it.

Claims

1. A production line for the automated manufacture of burglarproof grilles made of longitudinal sections or rods held together with the help of spacers or ties, and intended for mounting in side-frame sections which also enable rolling-up, said side-frame sections being of a type already found on the market as, for example, extruded aluminium sections, c h a r a c t e r i z e d by:

- a spool or reel (10) of steel wire (1) of sufficient thickness and hardness,

- a straightening press (15) to cold draw said wire (1) into a continuous length of straight and stiff working material,

- a bending module (20) to pull said wire (1) forward and to impart to said wire the desired wave shape,

- an annealing module (25) to anneal said wire on short, limited segments,

- a heating module (30) to heat said wire,

- a coating box (40) to coat said heated wire with nylon powder,

- a cooling module (50) to bring the temperature of said wire back to near room temperature,

- a trimming module (60) for cutting said wire to predetermined lengths,

- a collecting trough (70) to collect the cut lengths of said wire and position them in the required direction,

- an assembly table (80) for the assembly of said individual wire lengths with ties (2) to give a finished burglarproof grille.

2. The production line of claim 1, c h a r a c t e r¬ i z e d in that said wire (1) on said reel (10) has a diameter of more than 5 mm and a hardness equivalent to that of drawn carbon-enriched spring steel or better.

3. The production line of claim 1, c h a r a c t e r¬ i z e d in that said bending module (20) has bending wheels equipped with stamping sheets between their teeth to provide accuracy of reproduction of the bends, and in that the pressure on the wire section is adjusted to just over the material's yield point.

4. The production line of claim 1, c h a r a c t e r¬ i z e d in that said annealing module (25) brings the segments to be annealed to a temperature of about 700 degrees Celsius over a length of approximately 2 cm, and that said heating module (30) heats said wire to a temperature of 250 to 300 degrees Celsius with the help of a propane burner.

5. The production line of claim 1, c h a r a c t e r¬ i z e d in that an electrostatically charged nylon powder is blown into said coating box (40) and said powder melts on the surface of said hot steel wire.

6. The production line of claim 1, c h a r a c t e r¬ i z e d in that said trimming module (60) is controlled by a PLC.

7. The production line of claim 6, c h a r a c t e r¬ i z e d in that said trimming module (60) is equipped with a carriage and flying shears to trim said steel wire (1 ) .

8. The production line of claim 1, c h a r a c t e r¬ i z e d in that the feeding of said lengths of wire (1 ) to the feeding unit (82) of said assembly table (80) and the feeding of said ties (2) in the slots of the slide bars (88) is effected by pneumatic pistons (84,90).

9. A burglarproof grille for mounting in front of display windows or doors and consisting of preferably horizontal rods or sections with spacers, braces or ties which hold the elements together, and intended for mounting in side-frame sections on the sides of said windows or doors, c h a r a c t e r i z e d in that

- said rods (1) are produced by pulling drawn carbon- enriched spring steel from a reel (10) through a bending module (20) to be given an approximately sinusoidal wave shape before being coated with a hardwearing coloured nylon coating and trimmed to predetermined lengths,

- and said spacers or ties (2) are in the shape of rectangular pieces of hardwearing plastic, with perforations for said rods (1).

10. The burglarproof grille of claim 9, c h a r a c t e r i z e d in that every eighth said tie (2) has an embedded hardened steel chain as reinforcement, while said ties themselves have one or alternatively two separate perforations for the passage of said rods (1 ).