WO1997014893A1

WO1997014893A1 - Screw bolt

Info

Publication number: WO1997014893A1
Application number: PCT/SE1995/001240
Authority: WO
Inventors: Nils Gunnar Bertilsson; Miroslav Milurovic; Olle Persson
Original assignee: Moonlight Security Ab
Priority date: 1995-10-20
Filing date: 1995-10-20
Publication date: 1997-04-24
Also published as: AU4125696A

Abstract

The present invention relates to doors (29) of aluminium, said doors (29) being hung with external hinges (10-18, 21-26) screwed onto the door panel (29) and onto the frame (28). In known constructions the hinge (10-18, 21-26) is screwed on with bolts (2, 3 and 8) comprising a head (2 and 3) and a threaded penetration part (8). The head (2 and 3) can thus always be influenced by a screwdriver or a hexagon spanner. It is in this case the upper part (2) which can be influenced. According to the invention the bolt (2, 3 and 8) is arranged so that the lower part (3) of the head, when the bolt (2, 3 and 8) is screwed in, is situated in a recess (20) in the hinge (10-18, 21-26) while the upper part (2) of the head (2 and 3) is separated from the bolt (2, 3 and 8) if tampered with.

Description

S C R E W B O L T

The present invention relates to a screwbolt having a head and where the screw thread may be of various types such as machine-tapped or threading of the type found in wood screws. Screwbolts are generally used to join two units together and the head of the screwbolt is designed to be influenced by an adjustable wrench, screwdriver or hexagon spanner. Parts that can be joined together by a screwbolt are hinges and doors, for instance, or other optional units. A drawback, however, is that the screwbolt can extremely easily be removed, thereby separating the parts, and in certain cases this is not desired.

The object of the present invention is to create a screwbolt for joining together two units when it is desired that once these two units have been joined, it shall be impossible to separate them from each other by tampering with the screwbolt. According to the invention this is achieved in that screwbolt is provided with a head having a peripheral groove, the head thus having an upper part and a lower part, and the upper part being designed to be influenced by a tool or optional type. When a bolt has been screwed in so that two units are joined together, the through-hole in the one unit shall be provided with a recess so that when the screwbolt is screwed in and the two units therefore joined together, the lower part of the head of the screwbolt shall be situated in a recess in the other unit. Furthermore, the screwbolt shall be so tempered that it will withstand being tampered with except in the area around said peripheral groove, where the screwbolt shall have such properties that after it has been screwed in and is subjected to tightening action, a rupture occurs in the screw head whereby the upper part of the screw head is removed and the lower part of the screw head, which is of hard material and cannot be influenced, remains in the recessed opening. When a screwbolt according to the present invention is screwed in to retain two units, the screwing procedure is generally performed in such a manner that when complete, a rupture has been initiated between the upper and lower parts of the head. The invention is particularly suitable for door hinges where the hinge is external, i.e. the hinge is attached to a door frame and to the panel of a door and the attachment parts on the hinge are provided with openings having recesses so that the screwbolt, once inserted, has its lower part located in the recess. A door hung with hinges utilizing screwbolts according to the invention is extremely difficult to force since, during a break-in, the upper part of the screwbolt can quickly be removed but the lower part remains and is of such hard material that it cannot be tampered with.

The present invention will be described in more detail with reference to the accompany drawings, in which

Figure 1 shows a screwbolt according to the present invention, Figure 2 shows on an enlarged scale the upper part of a screwbolt, Figure 3 shows a hinge suitable for a screwbolt as shown in

Figure 1, Figure 4 shows a screwbolt according to the present invention in operation, Figure 5 shows a hinge designed for screwbolts as shown in Figure 1, where the attachment element of the hinge may be shielded by protective covers, Figure 6 shows a door with hinges utilizing screwbolts according to the present invention, and Figure 7 shows one of the hinges according to Figure 6.

Figures 1 and 2 show a screwbolt 1 with a head consisting of an upper part 2, a lower part 3 and a peripheral groove 4 between them. The screwbolt 1 also has a threaded penetration part 8 where the thread may be machine- tapped, a wood screw thread and / or a thread of any other suitable type whatsoever. The screwbolt itself is of hard material which is not affected by machining units such as drills. The hardness of the screwbolt is obtained by means of tempering. However, hardening has been performed in such a way that the material is weakened in the area around the peripheral groove 4. The upper part 2 of the head is provided with an opening 6 for a hexagon screw. The upper part may naturally be provided with a suitable groove for a screwdriver and the circumference of the upper part may be such that it can be manipulated by an adjustable wrench. However, the lower part 3 should under all circumstances be cylindrical. The weakened material around the groove 4 ensures that if the upper part 2 is subjected to a certain torsional force in relation to the lower part, a rupture will occur in the peripheral groove. The rupture will generally be located close to the upper surface 5 of the lower part. When screwing in a bolt according to the present invention, the actual screwing process may be performed so that, at its completion a rupture is initiated. However, this is not strictly necessary and instead a rupture may occur when the upper part is subjected to force to remove the bolt.

The bolt described above is intended primarily for use with a door hinge as shown in Figure 3. Said door hinge is designed to be applied on a door as shown in Figure 6, the attachment parts being secured to the door panel 29 and to the frame 28.

Considering Figure 3 once more, a hinge consists of an upper joint part 10 with attachment part 11, the latter having two holes 12 and 13 for bolts according to the present invention. The hinge is also provided with an intermediate part 14 with attachment part 15 having two holes 21 and 22 and, finally, the hinge has a lower part 16 with attachment part 17 having holes 23 and 24.

Figure 3 shows quite clearly that two screwbolts are inserted in the attachment part 15, where the penetration parts of the screwbolts are designed to penetrate into the door panel 29. The actual securing of a screwbolt according to the present invention is shown clearly in Figure 4 where it can also be seen that the through-hole 21 is provided with a hollow 19 for the actual threaded penetration part 8 and then a recess 20 for the head 2 and 3. It can be seen in the figure that the screwbolt is fully screwed in so that the attachment part 15 lies flush with one surface of the door 29. The threaded penetration part 8 is here screwed into the actual door 29 and the bolt head 2 and 3 is located in the recess 20 of the hole 21. In the present case the screwbolt 2, 3 and 8 has been tightened to such an extent that a rupture has started to appear in the groove part 4. This commencing rupture is designated 7. However, the screwbolt need not be tightened so far. It is sufficient for it to be tightened almost to the point of rupture so that, in the event of someone wishing to remove the screwbolt, this becomes impossible and when it is tampered with only the upper part 2 of the head will be removed leaving the flat surface of the lower part 3 of the head. The remaining part of the screwbolt is so hard that it cannot be removed with the aid of a drill or other manipulation tool.

Screwbolts according to the present invention are thus primarily intended to arrange a door 29 in a door opening with the aid of external hinges 30 and 31, said hinges being screwed in with screwbolts according to Figure 1. When the hinge is applied the attachment pieces are shielded by protective covers 18, 25 and 26.

It has been found that with doors hung using hinges as described above and attached with conventional screwbolts, the hinges can very quickly be removed thereby giving access to the area behind the door. On the other hand, if the hinges are secured with screwbolts according to the present invention, it has been found that it takes much too long to destroy the hinge since the upper part 2 of the bolt head is out of action.

Thanks to the present invention and the character of the screwbolts, it is possible to very appreciably impede a break-in via aluminium doors with external hinges, and a bolt according to the present invention therefore fulfils a considerable social function.

It should be evident that the hinges can be screwed in in such a manner that the upper part of the screw head is already separated during the tightening procedure.

Claims

1. A screwbolt with head, the free end of which is either designed for receipt of the blade of a screwdriver, one end of a polygon spanner such as a hexagon spanner, or has a circumference enabling it to cooperate with a spanner or the like and with a threaded portion in which the thread may be of various types, the bolt consisting of a single coherent unit, characterized in that the head (2 and 3) is provided between its ends with a peripheral groove (4), that the upper part (2) of the head is designed for said cooperation with said tools, that the screwbolt is so tempered that it has a hardness making it difficult to machine with the exception of a part inside said peripheral groove, where rupture may occur upon relative movement between the upper part (2) of the head and the remainder of the bolt (3 and 8), which occurs or is prepared for at the conclusion of a tightening process.

2. A screwbolt as claimed in claim 1, characterized in ^* that the bolt (2, 3 and 8) is made in such a way that upon said rupture the upper part (2) separates from the rest of the bolt (3 and 8).

3. A screwbolt as claimed in claim 1, characterized in that the bolt (2, 3 and 8) is inserted into a through-hole (21) to a part (15) to form a fixed part (15) of a hinge (10-18, 21-26) and with its hinged part (8) is screwed into a second part (28, or 29) such as a door or frame whereby when screwed in, the screwbolt (2, 3 and 8) joins said first part (15) and said second part (28) and whereby the part (3) of the screwbolt head (2 and 3) located below the peripheral groove (4) in screwed-in state is located in a recess (20).