METHOD FOR THE MANUFACTURE OF A CONICAL TUBULAR MEMBER, AND A MEMBER MANUFACTURED ACCORDING TO THE METHOD

Abstract: Method for the manufacture of a conical tubular member, and a member manufactured according to the method, in which as a first step a tubular member is formed, having inwardly directed profilings (2, 2', 3, 3'), and that said member thereafter is placed over a core with grooves arranged to receive said profilings (2, 2', 3, 3') and having a conical shape substantially corresponding to the internal shape of the member to be manufactured. By means of hydraulically and/or pneumatically applied force, divided over the surface of the tubular member by means of at least one flexible pressure applying means arranged surrounding the tubular member, said member is thereafter given a conical shape corresponding to the shape of the core, the reduction in diameter of the member being compensated for by means of a change in the shape of the profilings (2, 2', 3, 3'). The member is advantageously manufactured from a material having through perforations, or a wire mesh material.

Description: METHOD FOR THE MANUFACTURE OF A CONICAL TUBULAR MEMBER, AND A MEMBER MANUFACTURED ACCORDING TO THE METHOD The present invention relates to a method for the manufacture of a conical tubular member, and a member manufactured according to the method For a number of different applications, there is a need for tubular elements, having a conically reduced cross-section in longitudinal direction, for example used as poles and masts, flag-poles, and for many other fields of application. Such tubular members, having a substantially cylindical cross-sectional configuration, can be manufactur with rather expensive manufacturing methods, e.g. by means of a drawformi operation in connection with a draw plate having variable diameter. Within many fields of application, it is not of primary importance that a conically tapered tubular member is arranged with a substantially circular cross-sectional configuration, but also other cross-sectional configurations are acceptable, and for certain applications also more desirable. The present invention relates to such tubular and conical members, which include longitudinally extending embossings or corrugations Conical tubular members of this type have previously been manufactured in various fashions, and a first example is disclosed in British Patent No. 7.754 of 1902, according to which patent a rectangular and plane blank first is arranged with substantially parallel corrugations extending from one edge portion, and with a succesively reduced depth in direction from said edge portion. These corrugations change the shape of the plane blank in such a way, that it thereafter can be bent into a conical and tubular member. An alternative method of manufacture is based on the use . of a cylindrical and tubular member as basic material, and that embossing rollers accomplish longitudinally extending corrugations or embossings in the tubular material, and examples of this manufacturing method are shown in British Patent No. 1.462.370 and French Patent No. 1.260.814. Previousl known methods of manufacture are thus based on two alternative blanks, either a plane blank, which in plane condition is arranged with parallel embossings having a succesively decreased depth, or a cylindrical and tubular member, which is brought into contact with embossing tools to accomplish longitudinally extending corrugations or embossings, when said tools are moved along the cylindrical and tubular member. To use a pre-shaped plane blank can be regarded as an acceptable method of manufacture, when the conical and tubular member to be manufactured has a relatively small length, and preferably also a relatively large angle of taper. However, to use a cylindrical tubular member as a blank, and to use embossing rollers which when moved in longitudinal direction of the member also succesively move towards the center axis of the member, is a method of manufacture that requires extremely complicated and thus also expensive machinery equipment, and it is also impossible to accomplish an end product, in which opposed sides of embossed or corrugated portions take up contact with each other, unless the corrugated tubular member in a final operation is made subject to pressure applied against the outer surface in order to further reduce accomplished diameter. A further problem is the spring return force of the material, and the difficulties in accomplishing substantially U-shaped embossings, having sharp corner portions at the bottom surfaces of the corrugations, and having side and bottom surfaces extending substantially plane. The object of the present invention is to disclose a method for the manufacture of a conical tubular member, suitable for manufacture of such members having a substantial length, and. ith the longitudinally extending corrugations arranged to accomplish maximum rigidity for the manufactured conical member. The resulting end product has exceptionally good rigidity and favourable tensile properties, but also other advantageous properties, which will be more fully discussed later. The important and characteristic features relating to the method according to the invention are disclosed in the main claim, and characteristic features relating to a member manufactured according to the method are disclosed in the subclaims relating to said member. The method according to the present invention, and conical tubular members manufactured according to the method, are more fully described below with reference to the enclosed drawings, in which:- Fig. 1 is a side view of a tubular blank, having a substantial ly uni form cross-section in longitudinal di rection. Fig. 2 is a cross-sectional view in enlarged scale of the blank shown in Fig. 1. Fig. 3 is a side view of a conical tubular member, formed from the blank shown in Figs. 1 and 2. Fig. 4 is an end view in enlarged scale of the tubular conical member shown in Fig. 3, viewed from the end portion having the smallest cross- sectional configuration. Fig. 5 is a perspective view of a first embodiment of a core, used in the forming operation resulting in a conical tubular member. Fig. 6 is a sche atical view of an example of a device used when manu- facturing according to the method of the invention. Fig. 7 is a side view of a conical tubular member, slightly modified in relation to the conical member shown in Figs. 3 and 4. The method according to the present invention is based on that a substantially plane corrugated strip member is bent to form a profiled tubular member 1, having a substantially uniform cross-section in longi¬ tudinal direction, as shown in Figs. 1 and 2. The longitudinally extending edge portions of the strip used as a blank can, as shown in Fig. 2, be arranged overlaying each other, and the each other overlaying edge portions can be joined together by rivets, welding or any other suitable method, and obviously also by means of a folded seam. Said profiled tubular member 1 can, as shown, include substantially V-shaped profilings 2, 2', 3, 3', i.e. profilings 2, 2 1 having a larger depth and profilings 3, 3" having a smaller depth arranged in intermediate positions between the deeper profilings 2, 2'. Also other types of profilin can obviously be used, e.g. V-shaped profilings having a uniform depth, U-shaped profilings, as well as other types of profilings which facilitate a change in the width of the profiling at least at the portions ehich coincide with the outer surface of the member 1. The tubular member 1 is thereafter placed in a position embracing a conical core 4, restricted outwardly by means of longitudinally extending contact surfaces 5, 5* , separated from each other by means of longitudinally extending grooves 6, 6 1 . Said contact surfaces 5, 5' are intended to serve as contact surfaces for the internal surfaces of the outer portions of the tubular member 1 during an afterfoilowing forming operation, whereas the intermediately located grooves 6, 6 1 are arranged to receive existing profilings 2, 2', 3, 3 1 at the tubular member 1. In order to press the tubular member 1 against the conical core 4, the present invention uses hydraulical or pneumatical pressure application, and a schematical example of such a method will now be disclosed with reference to Fig. 6. Said figure shows a surrounding tubular part 7, to the inside surface of which a flexible hose-shaped member 8 is attached with ' -its free end portion thus forming an expandable and longitudinally extending chamber 9. The lower portion of said chamber 9 is communicating via an outlet pipe 10 with a lower tank 11. Adjacent to the lower tank 11 a pump means P is arranged, arranged to pump liquid via pipe 12 from the lower tank 11 to an upper tank 13. Finally, said upper tank 13 is communicating with the upper portion of the chamber 9 via a pipe 14, and in this pipe 14 is also a valve means 15 arranged, intended to facilitate interruption of the flow communication between the upper tank 13 and the chamber 9. Centrally located within the portion of the tubular part.7 which is restricted -by the chamber 9, a core 4 is arranged, and in this embodiment the core 4 is arranged with a first portion having a cross-sectional configuration substantially corresponding to the internal cross-sectional configuration of the profiled tubular member 1. Said first portion is located adjacent to the lower tank 11, changing in direction towards the upper tank 13 into a conically reduced part, having a com " city corresponding to the com " city for the end product. Adjacent to the lower portion of thε core 4, an abutment member 16 is shown, preferably arranged movable in direction upwards along the core 4. The shown embodiment of a device for utilization of the method according to the present invention is when used arranged extending vertically, e.g. located under the surface level in a downwardly directed hole or shaft. Furthermore, the upper tank 13 is filled with water or other liquid medium, and the valve means 15 is closed. If the valve means 15 is opened liquid flows from the upper tank 13 via the pipe 14 and the chamber 9 to the outlet pipe 10, and thus to the lower tank 11. When the upper tank 13 has been almost emptied, the valve means 15 is closed again, whereby a vacuum is created in the chamber 9. Said vacuum causes the hose-shaped and flexible member 8 to be pressed into a contact position agains the internal surface of the tubular part 7. A profiled tubular member 1 is thereafter inserted into the tubular part 7 in such a way, that said member 1 surrounds the core 4. The abutment member 16 should now be located adjacent to the lower portion of the core 4, whereby only a first and upper portion of the member 1 is located by a first portion of the conical part of the core 4. Thereafter, the valve means 15 is opened, which previously has caused the flexible member 8 to be pressed against the tubular part 7, and said flexible part 8 is hereby moved to a more adjacent position to the inserted profiled member 1. The . valve means 15 can now be closed again, and by means of the pump P liquid is now pumped up from the lower tank to the upper tank 13. A valve means 17 in the outlet pipe 10 is thereafter partly closed, and the valve means 15 adjacent to the upper tank 13 opened. Liquid will now flow in direction towards the lower tank 11, and also fill the chamber 9, and the lower valve means 17 can now be arranged substantially completely closed for a shorter period of time. The pressure of the liquid column in the chamber 9 now causes pressure application of the flexible part against the core 4, and thus also against the part of the profiled tubular member 1 which as a first step only surrounds a limited portion of the conical part of the core 4, whereby said portion of the tubular element 1 is formed into a conical shape. This change in the shape is made possible due to changes in the width and/or the depth of existing profilings 2, 2', 3, 3' in the tubular member 1. When a first forming operation has been performed in the described manner, the upper valve means 15 is closed again, and the lower valve means 17 is completely opened, whereby previously described vacuum effect is caused with regard to the chamber 9, i.e. the flexible part 8 is moved from a position in contact against the core 4 and the tubular member 1 to the previously described position in contact with the tubular part 7. The abutment member 16 is now moved in direction upwards, thereby also moving the profiled tubular element 1 a corresponding distance in direction upwards, whereafter the previously described operation is repeated. These operations are repeated until the abutment member 16 is located adjacent to the part of the core 4, where the conical part of the core 4 starts, and this conical part should obviously have an extension corresponding to, or exceeding, the total length of the profiled tubular member 1. The fact that the forming operation is performed gradually, as succesive steps, is related to the otherwise existing. risk that the profilings 2, 2', 3, 3' do not enter the grooves 6, 6' of the core 4, and this risk is considerable adjacent to the end portion of the tubular member 1 having the smallest diameter after forming. By performing the forming operation as a number of succesive steps, whereby a certain portion of the tubular member 1 in steps gradually is reduced with regard to diameter, complete safety is obtained for entering of the profilings 2, 2', 3, 3' into the existing grooves 6, 6' at the core 4. The number of forming operations is obviously related to the com " city of the end product, but in order to obtain maximum safety, the tubular member 1 should be moved such a distance between each forming operation in relation to the core 4, that the profilin 2, 2', 3, 3' are located adjacent to-the grooves 6, 6' in the core 4 into which they should enter in the next forming operation. In order to reduce the number of forming operations, it is also possible to use alternative solutions. An example of such a modification is shown in Fig. 5, according to which the core 4 has been modified with a number of guiding members 18, 18', extending bowshaped from the outer contact surfaces 5, 5' of the core 4. Said guiding members 18, 18' can comprise of members similar to blade springs, attached at one end portion, and when compressed arranged to form a part of the contact surface 5, 5 1 to which each guiding member 18, 18' is attached. Said guiding members 18, 18' can in certain cases reduce the number of forming operations to one only, which obviously reduces the manufacturing cost considerably. A further alternative method to reduce the number of forming operations necessary exists in the possibility to divide the chamber 9 in a number of sections, divided from each other in the longitudinal direction of the core 4. For example, such a division can be arranged in such a way, that a number of individually expandable sections are arranged within the tubular part 7, comparable to tubes of the type used in vehicle tyres which should be arranged in adjacent positions to each other. Said expandable sections are preferably first evacuated of the medium used, when the profiled tubular member 1 is inserted into a position embracing the core 4. Thereafter is a succesively performed forming operation initiated, by expanding the section most adjacent to the larger part of the conical core 4 by means of supplied gaseous or liquid medium, and following sections are thereafter succesively filled with gaseous or liquid medium under pressure. Hereby are existing profilings 2, 2', 3, 3' gradually pressed into the grooves 6, 6 1 of the core 4, and the risk for non-entering of said profilings 2, 2', 3, 3' into co-acting grooves 6, 6' in the core 4 is substantially completely eliminated. This method can advantegeously be combined with the type of a core 4 as described with reference to Fig. 5, in order to obtain even higher security for a correctly performed forming operation. It should also be mentioned, that the embodiment described with reference to Fig. 6 obviously also can be used with a gaseous medium under pressure, and that the forming operation not necessarily must be performed with the core 4 arranged extending vertically.However, such a position of extension when using a liquid medium, often results in that the pressure of the liquid column is satisfactory for performing a compkete forming operation. An interesting aspect related to the forming method according to the present invention is also, that the profilated tubular m-mber 1 can be manufactured from sheet metal having through perforations. Mechanical forming operations, e.g. of the type disclosed as prior art, prevents the use of perforated sheet metal, since perforations prevent the use of mechanically applied rollers or similar types of shaping tools. An example of such a conical perforated tubular member is disclosed in Fig. 7, and the advantages of using perforated sheet metal is firstly that complete through ventilation is achieved, which substantially completely eliminates the risk for damage through corrosion associated with metallic poles and masts, arranged with a solid surrounding surface, and secondly, such a mast or pole can also be climbed using conventional climbing irons, if the seizing members are arranged with a surrounding hose or layer of rubber or similar flexible material, enters the perforations when climbing, thereby causing an extremely safe grip. Said safe grip is further accentuated by the conical shape, which means that a pole or a mast has a gradually increasing cross-section in directi downwards. A further advantage by using perforated sheet metal as base material is, apart from the reduction in weight, that a pole or mast located adjacent to a road surface, and thus is made subject to light from moving light sources (vehicles), also result in a "light organ effect", which makes it extremely easy to observe such a pole or mast. This effect is extremely significant, and a passing driver in a vehicle can not fail to notice the pole or the mast when driving under bad light conditions. As a result, good safety is achieved for noticing poles or mas before same is passed by vehicles. The basic embodiments discussed above with reference to the possibility to use perforated sheet metal, also includes other types of material, such as wire mesh materials. Such materials can advantageously be formed according to the method of manufacture previously discussed, and makes it possible to manufacture poles, masts or similar, having complete through visiability. By a suitable choice of mesh size and wire diameter, it is also possible to cater for desired tensile strength properties. An interesting aspect of conical tubular members, manufactured according to the present invention, is that existing profilings 2, 2', 3, 3' not only serve as elements improving rigidity, and also facilitate forming into a conical end product. At any choosen diameter, a conical tubular member according to the present invention has a considerably larger tόtaili circumference than a conical tubular member having a cylindrical outer surface. By varying the depth and the number of profilings 2, 2 1 , 3, 3' used, it is thus possible to accomplish basically any desired total surrounding length of material, and this length is also maintained at every point in longitudinal direction of the end product. It should be emphasized, that the examples previously given relating to manufacturing technique when using the method according to the present invention obviously can be varied further in a number of ways, while maintaining the characteristic features related to each example, which are, that as a first step a cylindrical tubular member 1 is formed, having at least one longitudinally extending profiling 2, 2', 3, 3 1 directed towards the internal surface of the member 1, and that said member in a subsequent step is placed over a conical core 4 having grooves for the profilings 2, 2 1 , 3, 3' in the member 1, and that said member by means of pneumatic or hydraulic force is brought to take up a shape corresponding to the core 4, and that said change in form is accomplished by a change in the shape of existing profilings 2, 2', 3, 3'. The present invention is thus in no way restricted to shown and described examples of embodiments, but can be varied within the sc.ope of the inventi thought and the following claims.

Claims: C L A S 1. Method for the manufacture of a conical tubular member, c h a r a c t e r i s e d i n, that as a first step a tubular member is formed, having at least one profiling extending in longitudinal direction of the member, extending in direction towards the internal surface of the member, that said member as a second step is located embracing a conical core having grooves corresponding to the profilings of the member, and that said member as a third step by means of applied hydraulic and/or pneumatic force is pressed against the core, said application of force being arranged to give the m-mber a substantially conical shape by a change of existing profilings cross-section. 2. Method according to claim 1, c h a r a c t e r i s e d i n, that the first step includes a bending operation of a logitudinally profilated and preferably strip-shaped member into a tubular member, and that the edge portions bent towards each other are joined together. 3. Method according to any of claims 1 and 2, c h a r a c t e r i s e d i n, that the appl cation of hydraulic and/or pneumatic force against the tubular member in direction towards the core is accomplished by means of at least one flexible force applying member surrounding the member, arranged to take up contact with the tubular member by means of hydraulic and/or pneumatic force application, thereby changing the shape of same into a shape substantially corresponding to the shape of the core. 4. Method according to any of claims 1 - 3, c!:h a r a c t e r i s e d i n, that the third step includes in successive steps shape adjustment of the tubular member to the embraced core, and that said successive shape adjustment is performed by moving the tubular member in successive steps in relation to the core, each movement being followed by a forming operation, and that shape adjustment in the first step is performed adjacent to the larger portion of the core. 5. Method according to any of claims 1 - 3, c h a r a c t e r i s e d i n, that the third step includes shape adjustment of the tubular member to the embraced core in successive steps, and that said successive shape adjustment is performed as shape adjustment of the tubular member to the core in successively following steps and zones, and that said shape adjustment is performed in steps commencing from the larger portion of the core. 6. Method according to any of claims 1 - 5, c h a r a c t e r i s e d i n, that the tubular .member is guided in relation to the core during the shape adjustment of the tubular member to the conical shape of the core by means of guiding members extending from the core, which form planes coinciding with the planes of the core when complete shape adjustme is accomplished. 7. Conical tubular member manufactured according to the method in any of claims 1 - 6, c h a r a c t e r i s e d i n, that it comprises of a conical tubular member, including at least one inwardly directed profiling (2, 2', 3, 3') extending in longitudinal direction, amd that said profilin (2, 2', 3, 3 T ) has a continously varied cross-sectional configuration in longitudinal direction. 8. Conical tubular member according to claim 7, c h a r a c t e r i s e i n, that it includes at least two longitudinally extending profilings (2, 2', 3, 3'), having different shape and/or depth in relation to each other. 9. Conical tubular member according to any of claims 7 and 8, c h a r a c t e r i s e d i n, that it has a number of through recesses, holes or perforations. 10. Conical tubular member according to any of claims 7 and 8, c h a r a c t e r i s e d i n, that it is manufactured from a wire mesh material.

Inventors: GEBELIUS SVEN RUNO VILHELM, GEBELIUS, SVEN, RUNO, VILHELM
Applicants: GEBELIUS SVEN RUNO VILHELM, GEBELIUS, SVEN, RUNO, VILHELM
Application year: 1983
Main classification: B21D51
IPC codes: B21C37, B21D15, B21D26, B21D41, B21D51