EP0487604B1

EP0487604B1 - A joint for structural members

Info

Publication number: EP0487604B1
Application number: EP90912900A
Authority: EP
Inventors: Henrik Thorning
Original assignee: Fiberline AS
Current assignee: Fiberline AS
Priority date: 1989-08-14
Filing date: 1990-08-14
Publication date: 1994-01-05
Anticipated expiration: 2010-08-14
Also published as: DE69005826T2; ES2047948T3; DK398489D0; DK168243B1; WO1991002922A1; AU6279990A; EP0487604A1; DE69005826D1; DK398489A

Abstract

A joint (1) for structural members, such as a grating, and comprising a number of structural members (2) fixed in parallel at regular intervals. Bars (3) extend transversely through openings in the structural members (2), intermediary and outer tubular members (4, 4') being shrunk on said bars. The tubular members (4, 4') are preferably made of a plastic material capable of forming internal cross bondings and capable of shrinking when subjected to heat from the outside. In this manner a joint (1) for structural members is achieved, which is both substantially faster and less expensive to manufacture than the previously known types of joints for structural members.

Description

The invention relates to a joint for structural members and comprising two or more structural members fixed relative to one another at regular intervals by means of bars extending through openings in said structural members as well as by means of intermediary and outer tubular locking members mounted on said bars.
Joints of the above type for structural members are used for instance for gratings, fencing gratings, filtering units, Venetian blinds or the like. FR-A-2 596 246 discloses a grating with such joints. The known joints are provided with locking means for instance in form of grooves or notches in the bars. Simultaneously the bars often disclose complicated cross sections with the frequent result that the manufacture and assembling of the members of the joint into the ready joint are rather time-consuming and expensive Other types of joints for structural members are provided with locking means comprising screw means, which also makes the assembling of such joints rather time-consuming. These types of joints are furthermore encumbered with the drawback that the fixing of the locking means is often poor and unreliable.
The object of the invention is therefore to provide a joint for structural members, where the manufacture of the joint is especially fast and inexpensive, and where the members of said joints are quickly assembled into the ready joint, as well as where the locking members ensure a reliable fixing of the structural members.
The joint for structural members according to the invention is characterised in that the tubular locking members are shrunk onto the bars. As a result, a joint is obtained which is both substantially faster and less expensive to manufacture than the known joints, said joint simultaneously being considerably more durable and reliable than the known joints.
When the members of the joint are to be assembled into a ready joint, the structural members are at their openings pushed one by one over the bars while the desired intermediary tubular members are simultaneously inserted between said structural members. Subsequently, all the tubular locking members are shrunk onto the bars by means of for instance heat fed from the outside.
According to the invention the ends of the tubular members may abut on the adjacent structural members with the result that a particularly rigid joint is achieved.
Moreover according to the invention the tubular members may be made of a plastic material capable of being caused to enter a shrinkable state, whereby a particularly simple and inexpensive manufacture of the joint is obtained.
Furthermore according to the invention the inner surfaces of the tubular members may be provided with an adhesive coating, said inner surfaces being capable of engaging the outer surfaces of the bars in connection with the mounting procedure. In this manner an especially good fixing of the tubular members on the bars is achieved.
In addition according to the invention the bars may be made of a plastic material, and the inner surfaces of the tubular members may be provided with a welding coating of plastic material of a flow temperature which is lower than the crystallization temperature of the plastic material of the tubular members, said inner surfaces of the tubular members being capable of engaging the outer surfaces of the bars in connection with the mounting procedure.
The resulting fixing of the tubular members on the bars is particularly good, and accordingly a particularly strong and durable joint is achieved.
Finally according to the invention, the tubular members and the bars may be of inner and outer, respectively, mating circular cross sections.

Brief Description of Drawing

The invention is described in greater detail below with reference to the accompanying drawing, in which

Fig. 1 is a top view of a joint for structural members and to be used as a grating, and
Fig. 2 is a side view of the joint of Fig. 1.

Best Mode for Carrying Out the Invention

Fig. 1 shows a joint 1 for structural members and comprising four structural members 2. The four structural members 2 are fixed at regular intervals in such a manner that they extend in parallel in the same plane. The structural members 2 are of a closed quadrangular cross section, and the illustrated joint 1 is preferably used as a grating unit.
The illustrated joint for structural members is in no way to be considered a limitation of the scope of the invention as the joint can comprise an arbitrary number of structural members. The structural members need not extend in parallel nor do they need to be arranged in the same plane because the joint for structural members can just as well be used for a space grating unit.
The joint 1 for structural members comprises furthermore bars 3 transversely extending through openings (not shown) in the structural members 2 so as to interconnect said structural members. Tubular members 4' and 4 are shrunk onto the bars 3 at the ends of said bars and between the structural members 2. The ends of the tubular members 4 and 4' are preferably permanently abutting on the adjacent structural members 2 with the result that said structural members are reliably fixed relative to one another. In this manner the joint 1 for structural members is both particularly rigid and strong.
The tubular members 4, 4' are made of a plastic material which can be caused to enter a shrinkable state. The plastic material can for instance be hard PVC or technical types of plastics, such as polyethylene, capable of forming internal cross bondings PEX. The plastic material may optionally be fiber reinforced. Like the bars 3, the tubular members 4, 4' are preferably of a circular cross section and cut in suitable lengths from an extruded or injection moulded pipe. Already during or not until after the manufacturing process, the pipe is such that the plastic material has formed internal cross bondings. After the manufacture and when the pipe is made of for instance polyethylene containing Silan™ and catalyst, the cross bondings can for instance be provided by the material being boiled in water. Subsequently, the pipe is subjected to heat until its inner diameter has been enlarged sufficiently for allowing insertion over the bars 3 of the tubular members 4, 4' cut out of the pipe. The structural members 2 and the tubular members 4, 4' are especially quickly and easily mounted on the bars 3 by said structural members 2 being pushed one by one over the bars 3 simultaneously with a tubular member 4 being inserted on each bar 3 between two succeeding structural members. The tubular members 4, 4' are now subjected to heat while they are simply retained at each end of the bars 3, preferably in such a manner that they firmly join the structural members 2. The tubular members 4, 4' are heated in such a manner that they reach or exceed the crystallization temperature of the plastic material with the result that said tubular members are shrunk onto the bars 3. The resulting assembling of the structural members is especially fast, easy and uncomplicated. In addition, the manufacture of the joint is particularly inexpensive, in fact the production costs have been reduced by up to 50% compared to the previously known complicated assembling methods.
The tubular members 4, 4' can also be provided with an adhesive on their inner surfaces. As a result, the tubular members are extremely reliably fixed on the bars 3 after the shrinking thereon. When the bars 3 are made of a plastic material, such as polyethylene, the inner surfaces of the tubular members 4, 4' can be provided with a welding coating of a plastic material, such as polyethylene, of a flow temperature which is lower than the crystallization temperature of the plastic material of the tubular members 4, 4'. In this manner the tubular members 4, 4' are fixed on the bars 3 in a particularly strong and durable manner.
The tubular members 4, 4' are preferably of a closed cross section, whereby they encircle the bars 3 completely after the shrinking. The tubular members can, however, just as well be of an open cross section, such as in form of longitudinally slit lengths of pipe, whereby the members can be pressed over the bars from the side before they are shrunk thereon.
The joint according to the invention is particularly suited for the assembling of structural members made of light and strong materials, such as carbon-fiber or KEVLAR™-reinforced epoxy or glass fiber reinforced polyester.
The invention has been described with reference to an especially preferred embodiment, but it is in no way limited to such an embodiment. The structural members may for instance be of many other cross sections beyond the illustrated closed quandrangles. Furthermore, the members may, as mentioned above, be made of many different materials including metals, such as aluminium. The joint according to the invention is used especially in connection with the manufacture of gratings, fencing gratings, filtering units, Venetian blinds or the like.

Claims

A joint for structural members and comprising two or more structural members fixed relative to one another at regular intervals by means of bars extending through openings in said structural members as well as by means of intermediary and outer tubular locking members mounted on said bars, characterised in that the tubular locking members (4, 4') are shrunk onto the bars (3).
A joint as claimed in claim 1, characterised in that the ends of the tubular members (4, 4') abut on the adjacent structural members (2).
A joint as claim in claim 1 or 2, characterised in that the tubular members (4, 4') are made of a plastic material capable of being caused to enter a shrinkable state.
A joint as claimed in one or more of the preceding claims, characterised in that the inner surfaces of the tubular members (4, 4') are provided with an adhesive coating, said inner surfaces being capable of engaging the outer surfaces of the bars (3) in connection with the mounting procedure.
A joint as claimed in one or more of the claims 1 to 3, characterised in that the bars (3) are made of a plastic material, and that the inner surfaces of the tubular members (4, 4') are provided with a welding coating of plastic material of a flow temperature which is lower than the crystallization temperature of the plastic material of the tubular members (4, 4'), said inner surfaces of the tubular members being capable of engaging the outer surfaces of the bars (3) in connection with the mounting procedure.
A joint as claimed in one or more of the preceding claims, characterised in that the tubular members (4, 4') and the bars (3) are of inner and outer, respectively, mating circular cross sections.