TUBE OF COMPOSITE MATERIAL

Abstract: A high quality composite tube consists of a plastic-impregnated tubular interweave of threads or fibres, the angle of which with respect to the centre line of the tube is the determining factor for the diameter. At least one end of the interweave is widened and folded over outwards or inwards one or more times. The widened end can serve as the connection element with another tube.

Description: Title: Tube of composite material The invention relates to a high quality composite tube consisting of a plastic-impregnated tubular interweave of threads or fibres, the angle of which with respect to the centre line of the tube is the determining factor for the diameter. Composite tubes of this type are used, inter alia, as the drive shaft for helicopters, and are known for their great torsional strength. The connecting flange can form an integral whole with the tube. A drawback of the use of a tubular interweave can be that the ends of the tubes rapidly start to fray. The aim of the invention is to overcome this drawback and also to make the tube of such construction that the latter is outstandingly suitable for joining by one or both ends to another tube. According to the invention, the tube mentioned in the preamble is, to this end, characterised in that at least one end of the interweave is widened and folded over outwards or inwards one or more times, the widened end being able to serve as the connection element with another tube. The connection between one tube and another can be effected by means of the plastic impregnation itself or, after the plastic impregnation has been applied separately, by gluing. If the tube runs at an angle with respect to another tube, said other tube can be clicked into the saddle-shaped widening of the first tube which fits around it. The one and the other tube can also be in line with one another. The invention also relates to a tubular connection piece, the one widened end of which is joined to a first tube which runs at an angle with respect to the connection piece and the other end of which is joined to a second tube which extends in line with the connection piece. The fibres or threads preferably consist of glass, ara ide or carbon and the plastic impregnation preferably consists of epoxy resin or polyester. The invention will be explained in more detail with reference to the figures. Figure 1 shows a first embodiment of part of a tube according to the invention. Figure 2 shows a second embodiment of part of the tube according to the invention. Figure 3 shows a connection construction for two metal or plastic tubes running perpendicular to one another. Figure -4 shows two composite tubes joined to one another. Figure 5 shows a cross-section through the tubes according to Figure . Figure 6 shows a tube according to the invention which is joined to a second tube in line therewith. Figure 7 shows a bicycle in which use has been made of tubular connection pieces according to the invention. Figure 1 shows part of a tube consisting of a tubular interweave 1 made of threads or fibres of glass, carbon or aramide or another strong plastic, and an impregnation of epoxy resin, polyester or another suitable plastic. For the sake of clarity, only the interweave is shown on the left; both the interweave and the impregnation are shown on the right. The threads or fibres of the interweave make an angle with respect to the centre line of the tubular interweave and a mathematical relationship exists between this angle and the diameter of the interweave. For each transition it is possible to calculate what the fibre angle will be and how strong the construction is. The important feature is that the end shown at 2 is widened in a flare and the interweave is folded over. This folding over is shown as a single fold outwards in Figure 1 and as multiple folds inwards in Figure 2. Figure 3 shows that a composite tube 6 (indicated by dash-and-dot lines) according to Figure 1 or 2 is fitted around a metal or plastic tube 5» that a composite tube 8 (dash-and-dot lines) is fitted around a metal or plastic tube 7 and that a connection is made between the composite tubes 6 and 8 whereby the vertical composite tube 6 is provided with the abovementioned flared end 2 and the wall of the tubes 7 and 8 is provided with an opening 3• The flared end section of the composite tube 6, which end section is folded over, extends in a saddle shape over the horizontal pipes 7 and 8 at the location of the opening 3» Figure 4 shows the connection between two composite tubes running perpendicular to one another. As can be seen from Figure 5. the horizontal pipe has been, as it were, clicked into the widening 2 of the vertical pipe. The connection between the two pipes in this position can be effected by the plastic impregnation which is applied after the two tubular interweaves have been brought into the position according to Figure 3- Another possibility is that the two interweaves are provided with an impregnation beforehand and are glued to one another in the mutual position according to Figure 3- Figure 6 shows the situation where two pipes are connected in line with one another, the left hand pipe being provided with a widening 2 with fold-over, into which one end of the right hand pipe has been inserted. The overlapping pipe sections are joined to one another by a common impregnation or by gluing. In the bicycle frame according to Figure 7. use has been made of various connection pieces 4 for joining together frame tubes which, in order to save weight, preferably also consist of plastic-impregnated interweave tubes. The connection pieces 4 have, at one end, the flared widened section 2 which fits in a saddle shape around a tube positioned at an angle with respect to the centre line of said connection pieces and, at the other end, a section which fits over a frame tube running in line with the centre line of the connection pieces. The most important aspects of the invention are the folded-over end of the interweave tube, as a result of which there is no fraying in a troublesome location, and the flared widening of a folded-over end, by which means a robust, easy to produce connection with .another tube can be provided.

Claims: Claims 1. High quality composite tube consisting of a plastic-impregnated tubular interweave of threads or fibres, the angle of which with respect to the centre line of the tube is the determining factor for the diameter, characterised in that at least one end of the interweave is widened and folded over outwards or inwards one or more times, the widened end being able to serve as the connection element with another tube. 2. Tube according to Claim 1 connected to another tube, characterised in that the connection between the one and the other tube is produced by the plastic impregnation. 3. Tube section according to Claim 1, connected to another tube, characterised in that the connection between the one and the other tube has been produced by gluing. 4. Tube according to Claim 2 or 3 > characterised in that said tube runs at an angle with respect to the other tube and said other tube has been clicked into the saddle-shaped widening of the first tube which fits around it. 5. Tube according to Claim 2 or 3. characterised in that the one tube and the other tube are in line with one another. 6. Tubular connection piece according to Claim 1, characterised in that the one widened end is joined to a tube which runs at an angle with respect to the tube section and the other end is joined to a second tube which extends in line with the connection piece. 7• Tube according to one of the preceding claims, characterised in that the fibres or threads consist of glass, aramide or carbon and the plastic impregnation consists of epoxy resin or polyester. 8. Pipes made of metal or plastic which run at an angle with respect to one another and are connected to one another in that a composite tube consisting of a plastic-impregnated tubular interweave has been fitted around both pipes, one of said composite tubes consisting of the tube according to Claim 1, which is joined by its flared end to the other composite tube.

Inventors: PEETERS JOHANNES HENDRICUS ALP, VERHEUS ALBERT SIMON, PEETERS, JOHANNES, HENDRICUS, ALPHONSUS, VERHEUS, ALBERT, SIMON
Applicants: PEETERS JOHANNES HENDRICUS ALP, TNO, VERHEUS ALBERT SIMON, NEDERLANDSE ORGANISATIE VOOR TOEGEPAST-NATUURWETEN, PEETERS, JOHANNES, HENDRICUS, ALPHONSUS, VERHEUS, ALBERT, SIMON
Application year: 1996
Main classification: F16L13
IPC codes: F16L9, F16L13