SUPPORTING TUBE FOR A TUBE CONSTRUCTION AND ITS MANUFACTURING PROCEDURE

Abstract: A supporting tube for a tubular structure, in particular a vertical post for a railing, a ladder step, or equivalent, having at least at one end a curved receptacle space where a crossing tube is connectable. On the curved margin of the curved space, the wall of the supporting tube has been bent to form a projecting supporting widening (2). The supporting widening has been made in that prior to cutting the supporting tube to desired length there has been drilled a hole at its cut-off point, the margins of which hole have been drawn out to form a collar projecting from the supporting tube, whereupon the supporting tube has been cut off so as to divide the collar into supporting widening arcs remaining on the ends of different supporting tubes.

Description: Supporting tube for a tube construction and its manufacturing procedure The present invention concerns a supporting tube for a tubular construction, in particular a vertical post for a railing, a ladder step, or equivalent, having at least at one end a curved space where a crossing tube can be connected. The invention also concerns the way in which such a supporting tube is manufactured- Tubular railings for operator's platforms, stairs etc. are usually made by welding. The junctions of tubes are adapted in various ways in order to facilitate the welding operation. With a view to reducing the amount of work that has to be done at the mounting site and to shortening the mounting time, pains are taken to make the railings with preassembly of elements as large as ever feasible in view of transportation. This kind of manufacturing requires accurate predi ensicning and a lot of design work. The structures and mounting sites of railings have to be designed and made with great care. Likewise, the railings as separate structures have to be designed and dimensioned in like manner. In the final assembly always some fitting remains to be done. The object of the invention is to eliminate for instance the problems mentioned above and to provide a supporting tube which better than heretofore enables lattice structures made cf tubular material to be manufactured. In the manufacturing of tubular railings for instance, the invention implements the principle that of the railing is only prefabricated the vertical post constituted by a supporting tube according to the invention, with the aid of which the railing is easy to construct on site to meet its special requirements. In other words, when in the prefabricated components the possibilities of assembling and joining the parts have been better taken into account, there is no need to extend the degree of prefabrication to include the making of large structural entities which are difficult to handle and to manage. In order to achieve these objects and aims of the invention, the supporting tube for a tubular construction of the invention is characterized in that on the curved margin of the curved space provided on its end the tube wall has been bent to form a projecting supporting widening. Such a supporting widening arc can be produced, as taught by the invention, in that prior to cutting the supporting tube to desired length a hole is drilled at the cross-cutting point and the margins of this hole are drawn to form a collar projecting from the tube, whereupon the supporting tube is cut off in a way such that the collar is divided between supporting widening arcs remaining on the ends of different supporting tubes. The invention is described in the following with reference made to the attached drawings, wherein:- Fig. 1 presents in elevational view a supporting tube according to the invention, in one of its manuf cturing stages, and Fig. 2 shows the same, turned through 90 degrees. Fig. 3 shows the same, seen from the end of the tube. Fig. 4 shows an application embodiment of the completed supporting tube, and Fig. 5 illustrates a detail in the juncture between the supporting tube and the crossing tube. The supporting widening to be provided on the end of the supporting tube 18 is manufactured by flanging collar branches on the vertical tube, centrally on both sides of the tube. This is accomplished as known in the art, by first drilling in the side of the tube a hole and then drawing the margins of the hole out to form a collar projecting from the tube. The collars have preferably an inner diameter consistent with the diameter of the supporting tube. When the supporting tube thus provided with collar is cut off with the saw at the centre 3 of the collar, one obtains two supporting tubes 18 having on their end the said supporting widening 2. When in such a supporting widening arc 2 is placed a tube or bar 4 of corresponding size, a well-fitting joint of two cylinders is obtained. The components may be conveniently affixed to each other by welding the straight edges 5 that have been formed at the cut-off point 3 to the sides of the crossing tube. It is also convenient to carry the weld around the edge of the supporting widening 2. The supporting widening enables the welding to be performed even on thin tubular materials by the TIG method, i.e., without additional material wire, because it is possible to melt down the margin of the supporting widening. When such welding is applied- there will be no harmful projecting seam. The joining is also conveniently accomplished from the supporting widening by screw or pop rivet attachment 6. The tube 4 fitted into the curved space 1 and the supporting widening 2 are drilled together and the joint is made with screws, self-tapping sheet screws or the like. Securing of the joint is also conveniently possible through an equivalent hole with a pop rivet or equivalent. The screws and rivets can be disposed in the supporting widening below the tube 4 resting in the curved space 1. With such placement, the heads of the screws or rivets will not catch on clcrhes or hands because they are located in the angle formed by the tubes. If desired, one or several intermediate tubes 7 parallelling the top tube 4 may be provided on the supporting tube. A good fit of such intermediate tubes is achieved by making collars S on the supporting tube at the desired point, opposing each other on both sides of the tube. The intermediate tubes are pushed into the holes thus formed, where¬ by the tubes "cross inside each other". The intermediate tube 7 and the supporting tube form a structure with very high diagonal rigidity. The extended collars offset the supporting points 9 for the wall of the supporting tube on the surface of the tube passing through to a distance substantially greater than that implied by the diameter of the supporting tube. The affixing to each other of the intermediate tube and the supporting tube may be conveniently accomplished in a number of ways. Welding and screw joint can be made as in the case of the top tube. At the intermediate tube 7, the collar goes around the tube and it is therefore possible to provide mechanical adherence between the tubes. Mechanical adherence is achieved in that the collar is squeezed from the outside with tongs of which the clamping jaws' arc conforms to the outer arc of the collar. When the pressure exerted is of such magnitude that the collar diameter is reduced and also presses the tube 7 therewithin to develop a constriction 10, a situation is generated in which the elastic and friction forces of the tubes keep them firmly locked together. The supporting tube is most convenient to attach to the skirting (toe lath) 11 of the passage level if a fixing projection 12 is welded to the lower end of the supporting tube. The projection 12 is so affixed to the supporting tube that a gap 13 corresponding to the thickness of the skirting is left between the end of the supporting tube and the projection. The projection 12 is provided with one or several threaded holes 14, into which screws are inserted. The supporting tube is placed in such engagement with the skirting 11 that the supporting tube and the projection 12 come to lie on different sides of the skirting 11, and the screws are tightened. Supporting tubes of this type can be manufactured as independent units and conveyed to the mounting site and simply ' disposed with the desired spacing. A railing is the formed when the intermediate tube 7 is pushed into the holes and the top tube 4 placed in its curved reseptacle spaces 1. Nothing but straight tubing is required on the job and the operations are limited to its cross-cutting and lengthening. It is easy to fit a bend, or another angle component, at angles because at the assembly stage the tubes are freely movable lengthwise, and adjustments in height can be ma e by means of the screw attachments of the supporting tube. When making railings for paper machines or in the foodstuff industry, stainless steel is very often used. In view of the high price of this material, endeavours are made to reduce the wall thickness of the tubing that is used. It is inconvenient to attach a thin-walled tube e.g. to a skirting by welding, and the resistance to bending afforded by one wall of the tube is poor. When the fixing projection 12 is so dimensioned that its lateral margins come to lie close to the centre-line of the supporting tube, the tube will also gain additional rigidity and a favourable bevel 15 for welding is obtained at the same time. If it is desired to affix the supporting tube to the skirting by welding, this can be done with ease and firmly in the angle 16 formed by the fixing projection and the skirting. The rigidity of the fixing projection 12 can be substantially in¬ creased with moderate material thickness if the projection is so dimensioned that at bending it is formed into a U beam with side flanges 17 of sufficient dimensions. When the fixing projection 12 is given such shape that its outer side subtends a small angle 19 with the supporting tube 18. By making use of this angle, the following advantages are gained: the supporting tubes cay at the mounting stage easily be secured to the skirting by wedging, e.g. with a suitable piece of bar iron. Thereby the supporting tube is secured well enough to remain in its place, but it can still be moved. : • It is possible, utilizing this angle 19 and the space between the fixing pro ection 12 and the skirting 11, to accomplish the fixing of the supporting tube simply by dropping a suitable cylindrical body 20 into this space. If the angle 19 is small enough, the attachment between the body 20 and projection 12 and the skirting 11 becomes self-tightening if anyone tries to pull the supporting member up. If, again, the cylindrical body 20 is knocked out from the wedge gap, the supporting member is at once easy to take off. In this way conveniently dismountable and remountable railing sections are obtained. Although in the foregoing the invention has been described in connection with a tubular railing, it is clear that the invention is equally well applicable in the making of any kind of lattice structure made of tubular material. In particular such ladders can be contemplated of which the steps have been made of supporting tubes according to the invention. Three-dimensional lattice structures, such as masts and pylons, may also be contemplated.

Claims: Claims 1. Supporting tube for a tubular structure, in particular a verti¬ cal post for a railing, having at least at one end a curved receptacle space (1) into which a crossing tube (4) can be connected, characterized in that on the curved margin of said curved space (1) the wall of the supporting tube (18) has been bent to form a projecting supporting widening (2). 2. Supporting tube according to claim 1, characterized in that the supporting tube has at one or several points mutually opposed collar widenings (8) . 3. Supporting tube according to claim 1, to one end of which has been welded a fixing projection (12), characterized in that the fixing projection (12) is shaped like a U beam and extends to the sides of the supporting tube (18) , forming a welding bevel (15) . 4. Supporting tube according to claim 3, characterized in that the fixing projection (12) has notches (13) substantially parallelling the centre-line of the supporting tube (18). 5. Supporting tube according to claim 3, characterized in that the outer side of the fixing projection (12) forms a wedge angle (19) together with the notches (13) in its U legs so that the wedge angle tapers down towards the end of the supporting tube. 6. Use of a supporting tube according to any one of claims 1-5 e.g. as vertical post of a railing, characterized in that into the supporting widening (2) on its end has been fitted a tube (4) con¬ forming to the radius of the supporting widening's arc and into its intermediate holes, if any, which have been provided with collar widenings (8), has been pushed an intermediate tube (7). 7. Use of a supporting tube according to claim 6, characterized in that the supporting tube (18) and the crossing tubes (4;7) are welded together at the margins of the widening arcs (2) and collar widenings (8), if any, pulled out from the wall of the supporting tube and/or along the straight end margin (5) constituted by the cut-off point (3) of the supporting tube. 8. A way of manufacturing a supporting tube according to claim 1, characterized in that prior to cutting the supporting tube to desired length, at its cut-off point is drilled a hole, of which the margins are drawn to form a collar (2) projecting from the tube, whereupon the supporting tube is cut off so that the collar is divided to form supporting widening arcs (2) which remain on the ends of different supporting tubes (18).

Inventors: RAUTAKOURA TIMO ILMARI
Applicants: RAUTAKOURA TIMO ILMARI
Application year: 1982
Main classification: E04F11
IPC codes: E04C3, E04F11, E06C1