Title of Invention

METHOD OF MANUFACTURING A VERTICAL SCAFFOLDING ELEMENT, AND ELEMENT THUS OBTAINED

Abstract

A method of manufacturing a vertical scaffolding element (16, 16') consisting of a tubular portion (14) to which is welded a star-shaped part (11) defining a number n of radially projecting sockets (17, 17', 17"), distributed peripherally in a star arrangement, intended for the attachment of one end of a horizontal crosspiece of the scaffolding wherein said vertical scaffolding element (16) consisting of a tubular portion (14) provided with a number n of radially projecting sockets (17), distributed peripherally in a star arrangement, designed for the attachment of one end of a horizontal crosspiece of the scaffolding; the sockets (17) are defined by a metal strip (1) folded in order to form a star-shaped part (11) closed on itself having protuberances forming the said sockets (17) alternating with re-entrant regions bearing against the tubular portion (14) the upper and lower edges of the re-entrant regions in contact with the tubular portion being welded thereto by continuous or discontinuous annular weld beads (15).

Full Text

The present invention relates to the field of scaffolding and, more specifically, it relates to improvements made to the vertical scaffolding elements consisting of a tubular portion provided with a certain number of radially projecting sockets, distributed peripherally in a star arrangement, intended for the attachment of one end of a horizontal transverse member of the scaffolding. Scaffolding elements of the type in question are described and shown, for example, in document FR-A-1 521 232. In the scaffolding elements of the type in question which are currently used, the sockets are manufactured individually, from a folded metal plate in the form of a U-shaped yoke, then welded individually to the tubular portion. Each edge of the U-shaped yoke is welded to the tubular portion both externally and possibly internally. This results, for a scaffolding element equipped with four sockets placed in a cross arrangement, in the need to produce eight linear weld lines extending longitudinally. In addition, the production of internal welds is complex and requires specific equipment capable of being engaged inside the sockets. The manufacture of this type of equipment proves to be difficult, lengthy and expensive. Documents GB-A-2 207 875 and FR-A-1 553 487 certainly show arrangements of scaffolding elements comprising a part shaped into a star arrangement, defining radial sockets for the attachment of transverse member(s). However, these star-shaped parts have a geometrical shape which does not allow easy manufacture with simple equipment by an unskilled worker. The aim of the invention is to overcome these drawbacks and to provide an improved solution for simplifying the manufacturing process, and in rendering it shorter, simpler and therefore less expensive. To these ends, according to a first of its aspects, the invention provides a method of manufacturing a vertical scaffolding element (16, 16') consisting of a tubular portion (14) to which is welded a star-shaped part (11) defining a number n of radially projecting sockets (17, 17', 17"), distributed peripherally in a star arrangement, intended for the attachment of one end of a horizontal crosspiece of the scaffolding, said process comprising the following steps: a) to stamp flat a plane metal strip (1) of a predetermined length at n regularly spaced locations so as to form n recesses (2) approximately in a dihedral arrangement (4a_ 4b) with a rounded ridge (3) transverse to the length of the strip, b) then to fold said so shaped strip at the joins (7, 10) of the ends of the faces (4a, 4b) of the dihedrals with the intermediate regions (5) of the strip so as to bring Closer to each other the lateral face.s (4a, 4b) of two adjacent recesses (2) which are located on each side of an intermediate region (5) of the strip and so as to position the rounded ridges (3) of the recesses (2) on an axisymmetric cylindrical outline (12) having substantially the same diameter as the external diameter of the tubular portion ,(14) in order to close said, strip on itself with free ends thereof being abutted, and so to form a star-shaped member (11) , c) to position said star-shaped member on said tubular portion with rounded ridges (3) of dinedrals formed by recesses (2) resting against the external surface of the tubular portion (14), and d) finally to weld said star-shaped member (11) to this latter,, characterized in that - after step b) of forming the star-shaped member-Ill) and before step c) , both abutted ends (6) of the strip are welded. (13) to each other so as to obtain an integral star-shaped member, and - during step d), said integral star-shaped member (11) is secured to the tubular portion (14) only by discontinuous circular welds (15) made on the upper and lower edges of the rounded ridges (3) resting on the tubular portion (14). By virtue of the invention, the sockets are no longer manufactured and secured individually to the tubular portion by a high number of longitudinal welds, but they result from the production of a star-shaped part'; and in addition, this, star-shaped part is obtained by simple stamping and folding operations on an initially flat metal strip, which part is then welded to the tubular portion by a small number of circular arc shaped welds which can be produced quickly with simple equipment, and without the need for skilled personnel. The cost of manufacturing a scaffolding element by implementing the method of the invention is considerably reduced, at the same time, the element is manufactured in a much shorter period of time. A considerable advantage will also be noted as regards safety. If a socket is torn off that is to say that its welds to the tubular portion are broken for example under the effect of 700 high a force, the torn socket continues to be integral with the-rest of the part, which, itself, remains secured to the tubular portions by its other welds. Thus, a crosspiece bearing on the torn socket is prevented from collapsing, as would happen with individual sockets. In a simple manner, provision is made that the recesses are formed as dihedra which are open over an angle of 2π/n. Also, advantageously, the stamped strip is folded so as to bring the lateral faces of two adjacent recesses into a substantially parallel mutual position. In a preferred embodiment which seems to constitute the most common practical application of the invention, provision may be made for the number of recesses to be four and for the angle a of opening of the dihedra formed by the recesses to be about 90°, by virtue of which a vertical scaffolding element is obtained, consisting of a tubular portion equipped with four sockets placed substantially in a cross arrangement. Preferably, the metal strip is treated such that the said abutted ends of the strip which are welded are located away from the end of a socket, so that the weld bead does not hamper the attachment of the additional scaffolding members to the socket. Advantageously, there will be a benefit in that the welded abutted ends of the strip are located in a region of the star-shaped part which bears against the tubular portion, such that the upper and lower ends of the weld bead are remelted during subsequent welding of the star-shaped part to the tubular portion. According to a second one of its aspects, the invention provides a vertical scaffolding element comprising four sockets defined by a metal strip folded in a cross arrangement with orthogonal branches and welded to a tubular portion which is characterized in that it is manufactured by implementing the method described above. The invention will be better understood on reading the following detailed description of certain embodiments given by way of purely illustrative example. In this description, reference is made to the appended drawings in which: Figures 1A to 1G illustrate successive steps in the manufacture of a preferred embodiment of a vertical scaffolding element according to the invention; Figure 2 is a perspective view of a vertical scaffolding element constructed according to the invention; Figures 3 and 4 are, respectively, two schematic views of variant embodiments of the star-shaped part of Figure 1E; and Figure 5 is a perspective view similar to that of Figure 2, showing a preferred variant embodiment. The method of the invention will now be explained with reference to Figures 1A to 1G, by considering more particularly a preferred embodiment with four sockets placed substantially in a cross arrangement, that is to say diametrally opposed in pairs along two perpendicular branches, since this is the configuration which, in practice, seems to have the most widespread application. Initially, a plane metal strip 1 of a predetermined length (Figure 1A, together with the following figures, in which the metal strip 1 is shown with no thickness, by a single line, for reasons of clarity) is formed. Next, diagonal bolt housings are punched out, this punching thus being carried out flat, under proper conditions. Then, the said strip 1 is flat-stamped at n (in this case four) regularly spaced locations so as to form n recesses 2 approximately in a dihedral arrangement with a rounded ridge 3 extending transversely for the length of the strip 1. Preferably, the dihedral recesses 2 are open over an angle a - 2π/n, which, in the case illustrated, is an angle of about 90°. As can be seen in Figure 1B, each dihedral recess 2 is therefore defined by two substantially plane walls 4a, 4b which are mutually inclined by the said angle a = 2π/n and which are joined by the rounded ridge 3. Two successive recesses 2 are separated by a flat undeformed region 5 of the strip 1. At the ends of the strip 1, a short portion 6 is stamped substantially perpendicular to the wall 4a or 4b of the adjacent recess 2. Next, on the strip stamped in this way with its recesses 2, a bending or folding operation is carried out on the strip by folding the metal strip at the joins of the ends of the faces 4a, 4b of the recesses with the intermediate flat regions 5 so as to bring closer to each other successive lateral faces 4a, 4b belonging respectively to two adjacent recesses which are located on each side of a flat region 5. In the example with four recesses taken into consideration here, the bending or folding operation is carried out in two steps. In Figure 1C, initially the two ends of the strip are folded by pivoting (arrow 8) the respective extreme recess 2 and the adjacent flat region 5 about the join 7 of the said flat region 5 with the adjacent recess 2. Then, on the intermediate part thus obtained (Figure 1C) , the two parts surrounding the central flat region 5 are folded by pivoting (arrow 9) about the joins 10 of the said parts with the said central flat region 5. Following on from this, a star-shaped part 11 provided with n branches mutually separated by an angle of 2π/n is obtained. In the example in question here, the star-shaped part 11 is cross-shaped with opposed arms, offset by 90°, as illustrated in Figure 1D. The short portions 6 of the ends of the strip 1 are abutted in order to form one end of one of the branches. The star-shaped part 11 is finished by welding, at 13, the aforementioned ends 6 edge to edge, such that an integral star-shaped part 11 is obtained, consisting of a metal strip closely following a closed outline with a complex shape as illustrated in Figure 1E (in this case, the part 11 has a cross section in the form of a cross with four branches). In addition, it will be noted that the rounded ridges 3 of the dihedral recesses 2 are all positioned on an axisymmetric cylindrical outline, the dimensions of the various deformed/folded parts of the strip 1 being chosen such that this cylindrical contour 12 (drawn in dotted lines in Figure 1D) has substantially the same diameter as the external diameter of a tubular mounting portion. Then, the star-shaped part 11 is pulled over and positioned on a tubular metal portion 14 (Figure 1F) , the rounded ridges 3 of the dihedra formed by the initial recesses 2 bearing against the outer face of the tubular portion 14. It may be emphasized here that there is a benefit in the cylinder of revolution 12 for positioning the rounded ridges 3 having a diameter which is very slightly less than that of the outer face of the tubular portion 14 so that the star-shaped part 11 elastically clamps the tubular portion 14 over which it is fitted: the star-shaped part 11 then remains in place without any other retaining means for the purpose of the following operation. Finally, the star-shaped part 11 is welded to the tubular portion 14: weld beads 15 (Figure 1G) are deposited, in two circular passes, on the upper and lower edges of the rounded ridges 3, that is at eight locations in the example illustrated in Figure 1G. Following on from which, a vertical scaffolding element is obtained, as illustrated in Figure 2, denoted, overall by the reference 16, which consists of a tubular portion 14 provided with a number n (in this case four) of radially projecting sockets 17 distributed peripherally in a star arrangement, the said sockets being intended for the attachment of one end of a horizontal crosspiece of the scaffolding. The configuration of the star-shaped part 11 and its weld to the tubular portion 14 by upper and lower circular arc-shaped weld beads 15 are clearly visible in Figure 2. The method of the invention overcomes the drawbacks associated with the manufacture and the securing of individual sockets. It makes it possible to manufacture all of the sockets 17 integrally, it being possible for the star-shaped part 11 to be obtained by implementing simple mechanical processes. Furthermore, its attachment to the tubular portion requires two welding operations carried out discontinuously, in a circular manner, over the periphery of the tubular portion, and therefore under very simple conditions. These two welding operations may be carried out in a single pass by using two welding apparatuses, or else in two successive passes. In the example envisaged above with regard to Figures 1A to 1G and 2, it has been assumed that the sockets have substantially parallel lateral faces, the folding operations (Figures 1C and 1D) being carried out as a consequence. However, the invention is not limited to this single configuration and it is possible to envisage an implementation of the method of the invention capable of leading to a star-shaped part 11', the branches 17' of which have a different shape, for example a tapered shape, as illustrated schematically in Figure 3. The branches 17' may have convergent walls joined at their end by a flattened transverse part 5' having a width less than the part 5 provided in. Figures 1A to 1G and 2. Even the transverse part 5' may be reduced to nothing with the convergent walls joining at a point. As a consequence, all that is needed for this is to adapt the stamping operation of Figure 1B (recesses 2 fairly close together, or even touching), and to adapt the folding operations of Figures 1C and 1D (bringing the walls 4a, 4b closer together so that they converge without becoming parallel). Furthermore, the invention is not limited to the manufacture of vertical scaffolding elements equipped with four sockets. It is possible, by the method of the invention, to manufacture elements having any number n of sockets spaced apart by an angle of 2π/n; in this case, the recesses 2 are formed, at the stamping step of Figure 2, with side walls 4a, 4b forming an angle of 2π/n between them. By way of example, Figure 4 illustrates schematically the shape of a vertical element 16' incorporating a star-shaped part 11" defining three sockets 17" separated by 120°, with convergent side walls according to the arrangements of Figure 3. In the exemplary embodiments which have just been described and which are illustrated in Figures 1A-1G and 2 to 4, the abutted ends of the metal strip folded according to the method of the invention are located approximately on the end of a socket. The weld bead 13 securing these ends risks causing problems for the attachment to the socket of scaffolding members. It may therefore prove desirable to make sure that the said abutted ends are located away from the end of the socket, for example laterally, or even preferably in a region of the star-shaped part 11 which bears against the tubular portion (that is to say in the re-entrant angle separating two consecutive sockets), as is clearly illustrated in Figure 5. In such an arrangement, the upper and lower ends of the weld 13 are remelted when welding the star-shaped part 11 on the tubular portion, which favourably affects the quality of these welds. Finally it may prove to be particularly beneficial, as illustrated in Figure 6, for the rounded ridges 3 to be shaped with their concavity turned outwards, such that these ridges 18 with a concave shape better follow the cylindrical outline of the tubular portion 14 to which they are applied and welded. WE CLAIM: 1. A method of manufacturing a vertical scaffolding element (16, 16') consisting of a tubular portion (14) to which is welded a star-shaped part (11) defining a number n of radially projecting sockets (17, 17', 17"), distributed peripherally in a star arrangement, intended for the attachment of one end of a horizontal crosspiece of the scaffolding, said process comprising the following steps: a) to stamp flat a plane metal strip (1) of a predetermined length at n regularly spaced locations so as to form n recesses (2) approximately in a dihedral arrangement (4a 4b) with a rounded ridge (3) transverse to the length of the strip, b) then to fold said so shaped strip at the joins (7, 10) of the ends of the faces (4a, 4b) of the dihedrals with the intermediate regions (5) of the strip so as to bring closer to each other the lateral faces (4a, 4b) of two adjacent recesses (2) which are located on each side of an intermediate region (5) of the strip and so. as to position the rounded ridges (3) of the recesses (2) on an axisymmetric cylindrical outline (12) having substantially the same diameter as the external diameter of the tubular portion (14) in order to close said strip on itself with free ends thereof being abutted and so to form a star-shaped member (11), c) to position said star-shaped member on said tubular portion with rounded ridges (3) of dihedrals formed by recesses (2) resting against the external surface of the tubular portion (14), and d) finally to weld said star-shaped member (11) to this latter, characterized in that - after step b) of forming the star-shaped member (11) and before step c), both abutted ends (6) of the strip are welded (13) to each other so as to obtain an integral star-shaped member, and - during step d), said integral star-shaped member (11) is secured to the tubular portion (14) only by discontinuous circular welds (15) made on the upper and lower edges of the rounded ridges (3) resting on the tubular portion (14). 2. Method as claimed in claim 1, wherein the recesses (2) are formed as dihedrals (4a, 4b).which are open over an angle of 2π/n. 3. Method as claimed in claim 1 or 2, wherein the stamped strip (1) is folded so as to bring the lateral faces (4a, 4b) of two adjacent recesses . (2) into a substantially parallel mutual position. 4. Method as claimed in anyone of claims 1 to 3, wherein the number of recesses (2) is four and in that the angle a of opening of the dihedrals (4a, 4b) formed by the recesses (2) is about 90°, whereby a vertical scaffolding element (16) is obtained] consisting of a tubular portion (14) equipped with four sockets (17, 17') placed substantially in a cross arrangement. 5. Method as claimed in anyone of claims 1 to 4, wherein the metal strip is treated such that said abutted ends of the strip which are welded are located on the end of a socket. 6. Method as claimed in anyone of claims 1 to 5, wherein the metal strip is treated such that the said abutted ends of the strip which are welded are located away from the end of a socket. 7. Method as claimed in claim 6, wherein the welded abutted ends of the strip are located in a region of the star-shaped member (11) which bears against the tubular portion (14). 8. Method as claimed in anyone of claims 1 to 7, wherein rounded ridges (3) are formed with their concavity turned outwards, so that these ridges can be applied tightly against the tubular portion (14). 9. A vertical scaffolding element manufactured by implementing the method as claimed in anyone of claims .1 to 8, wherein said element consisting of a tubular portion (14) to which is welded a star-shaped part (11) defining a number n of radially projecting sockets (17, 17', 17"), distributed peripherally in a star arrangement, intended for the attachment of one end of a horizontal crosspiece of the scaffolding, said star-shaped part consisting of a stamped metal strip (1) which is folded and closed on itself with ends thereof being abutted and welded to each other, said star-shaped part having rounded ridges (3) on an axisymmetric cylindrical outline (12). having substantially the same diameter as the external diameter of the tubular portion (14), said star-shaped member (11) being secured to said tubular portion (14) only by discontinuous circular welds (15) made on the upper and lower edges of the rounded ridges (3) resting on the tubular portion (14). ABSTRACT A method of manufacturing a vertical scaffolding element (16, 16') consisting of a tubular portion (14) to which is welded a star-shaped part (11) defining a number n of radially projecting sockets (17, 17', 17"), distributed peripherally in a star arrangement, intended for the attachment of one end of a horizontal crosspiece of the scaffolding wherein said vertical scaffolding element (16) consisting of a tubular portion (14) provided with a number n of radially projecting sockets (17), distributed peripherally in a star arrangement, designed for the attachment of one end of a horizontal crosspiece of the scaffolding; the sockets (17) are defined by a metal strip (1) folded in order to form a star-shaped part (11) closed on itself having protuberances forming the said sockets (17) alternating with re-entrant regions bearing against the tubular portion (14) the upper and lower edges of the re-entrant regions in contact with the tubular portion being welded thereto by continuous or discontinuous annular weld beads (15).

Documents:

541-CAL-2002-ABSTRACT.pdf

541-CAL-2002-CLAIMS.pdf

541-CAL-2002-CORRESPONDENCE.pdf

541-CAL-2002-DESCRIPTION (COMPLETE).pdf

541-CAL-2002-EXAMINATION REPORT.pdf

541-CAL-2002-FORM 1.pdf

541-CAL-2002-FORM 18.pdf

541-CAL-2002-FORM 2.pdf

541-CAL-2002-FORM 3.pdf

541-CAL-2002-FORM 5.pdf

541-CAL-2002-OTHERS.pdf

541-CAL-2002-REPLY TO EXAMINATION REPORT.pdf

541-CAL-2002-SPECIFICATION.pdf