Set of parts for connecting metallic structural tubes with a non-circular cross-section, process for producing the parts and use of same

Abstract

The invention relates to a set of metal parts that are placed inside structural metallic tubes having a non-circular, for example square, cross-section. The set of connecting parts according to the invention comprises a first L-shaped connecting part (10), which is produced from a metal sheet of a thickness identical to the thickness of the structural tubes to be connected. The first connecting part (10) is obtained by steps of cutting and bending, resulting in double-layer walls (88) and flaps (89) that allow the part to maintain its integral form, suitable for connecting two structural tubes. The present invention also relates to a process for producing the connecting or joining parts, comprising the steps of cutting, stamping, drilling, bending, and assembly.

Description

SET OF JOINT PARTS FOR NON-CIRCULAR SECTION METAL STRUCTURAL TUBES, PART PRODUCTION PROCESS AND USE

[0001] The subject matter of this application lies in the field of structural engineering and, more specifically, in the field of joining and fastening parts for metal structures, to ensure their stability, strength, and durability. In particular, the present invention relates to a set of parts that join rectangular or square metal pipes, eliminating the need for welding and other metal structure joining techniques. Background

[0002] Metal structure joining and fastening components play an essential role in the construction of metal tube structures. When selecting the structural construction methods to be adopted, speed, cost-effectiveness, and safety are essential aspects.

[0003] Metal has been used as a fundamental base in the construction of countless structures over the past few years. In this context, the connection of parts is paramount, particularly through methods that are effective and, above all, safe.

[0004] Furthermore, when it is intended to assemble metal structures for later disassembly, particularly for outdoor events, or in other non-definitive situations, disassembly renders the connecting parts and even the structural piping itself unusable, especially if it has been welded at the structure's joints.

[0005] Metal structures are widely used in construction and other sectors due to their high strength and malleability, particularly metal structures constructed with metal tubes. Proper joining of metal parts, such as metal tubes, is essential to ensure the structural integrity of the building. Over the years, various joining solutions have been developed, including welding, screws, rivets, and other mechanical fastening techniques.

[0006] However, traditional methods of joining pipes to metal structures present limitations and challenges. Welds can be complex to perform, requiring skilled labor and specialized equipment. Furthermore, welding introduces heat into the metal sheet or pipe and creates a heat-affected zone, which can lead to resistance problems due to the load and the consequent creation of uneven stresses in the structure. Welding is also a more time-consuming and demanding method, not only in terms of personnel safety requirements but also in terms of the equipment to be transported to the site.

[0007] For example, English patent application GB990438A, published on 1965-04-28, discloses a method of forming a joint between two tubular metal members having grooved sealing faces, in which the members are assembled with a soft metal washer between the faces, and a portion of at least one of the members is permanently deformed in such a way that the joint becomes plastic to form a seal between the faces. This method permanently deforms the pipes, which, on the one hand, imparts structural stress in the joint area and, on the other, is not suitable for structures that are not permanent in nature.

[0008] There is, therefore, a growing need for innovative solutions that overcome the limitations of traditional methods of joining metal structures, aiming to simplify installation, improve the distribution of tension and loads in the structure, particularly in the pipe joining area, and also ensure good corrosion resistance, in addition to the ability to adapt to different types of construction. Summary of the invention

[0009] The present invention relates to a set of metal parts that are placed inside non-circular structural metal tubes, for example, square or rectangular. The parts according to the present invention allow the connection of structural tubes in various directions and angles, without the need for any welding on the structural tubes.

[0010] The present invention also relates to a process for producing joining or connecting parts, comprising five main steps: cutting, stamping, drilling, bending, and assembly. The material used in the parts according to the present invention is sheet metal with the same wall thickness as the structural tubes to be joined. The measurements to be used prior to cutting the sheet metal vary according to the size and thickness of the structural tubes to be joined or connected. For example, in the case of an 80 x 80 mm tube, the dimensions of the joining part according to the invention will be approximately 76 x 76 mm.

[0011] The metal sheet from which the tubes according to the invention are produced may be a sheet of steel, iron, copper, bronze, brass, a metal alloy, or any type of metal that allows it to be bent.

[0012] In a first aspect, the present invention relates to a set of joining pieces for structural tubes of non-circular cross-section for preferably metallic structures.

[0013] In a second aspect, the present invention relates to a process for producing joining pieces of structural tubes of non-circular cross-section belonging to the set of the first aspect of the invention.

[0014] In a third aspect, the present invention relates to a use of the set of joining parts of the first aspect of the invention, produced according to the production process of the second aspect of the invention, wherein the use is in structures made with structural tubes of non-circular cross-section, preferably metallic. Problem Solution

[0015] The set of connecting pieces according to the invention comprises various metal pipe connecting pieces, namely a first L-shaped connecting piece, a second connecting piece with a closed end that receives holes for the passage of fasteners, such as screws, a third T-shaped connecting piece, and a fourth connecting piece with both ends open. The connecting pieces according to the invention are produced by a process comprising five steps: cutting, stamping, drilling, bending, and assembly, applied to one or more connecting pieces, in order to obtain pieces with a smooth outer surface, with an outer area only slightly smaller than the internal cross-sectional area of ​​the pipes to be joined, thus creating friction between the connecting pieces of the invention and the interior of the pipes to be joined.

[0016] Preferably, the structural tubes are screwed into the joining pieces to ensure greater stability and strength, depending on the size of the structural tubes, their length and the stresses to which the structure will be subjected.

[0017] Thus, structural tubes with a non-circular cross-section, such as square cross-section, which are not part of the present invention, can be joined at their ends, as explained later in this application, forming structures with the desired configuration without requiring welding. This allows the tube structure to be assembled more quickly and safely. Furthermore, in cases where the structure is not permanent, such as in stages for summer shows, sporting events, or other events, the structural tubes, after being quickly and easily disassembled, can be reused in another structure, using the parts according to the invention to join them.

[0018] The set of parts according to the invention can also join structural tubes made of non-metallic materials, such as plastic structural tubes, provided they have the appropriate dimensions so that they can be joined by the joining parts according to the invention. Advantageous Effects of the Invention

[0019] The set of connecting and fastening parts and their production method have the advantage of allowing the use of non-circular cross-section pipes, such as square or rectangular, in various sizes and thicknesses available on the market. This eliminates the need for welding to join structural pipes, which, in addition to avoiding the disadvantages inherent to welding techniques mentioned above, also allows for faster, safer, more economical, and more aesthetically pleasing structural construction. Furthermore, it also allows for easier subsequent disassembly of the structure, if necessary, with the possibility of reusing all the piping and connecting parts according to the invention.

[0020] The parts of the inventive assembly are connected from the inside of the structural tubes, providing additional security to the structure. Although the structural tubes must be fastened with screws, rivets, or glue, preferably screws, from the outside of the structural tubes, the assembly of parts of the present invention offers the advantages mentioned above.

[0021] For the purpose of promoting an understanding of the principles underlying the embodiments of the present invention, reference will be made to the embodiments illustrated in the figures and the language employed to describe them. In any event, it should be understood that there is no intention to limit the scope of the present invention to the content of the figures. Any subsequent changes or modifications to the inventive features illustrated herein, as well as any additional applications of the principles and embodiments of the invention illustrated, which would normally occur to one skilled in the art in possession of this description, are considered within the scope of the claimed invention. Fig. 1

[0022] [Fig. 1] represents a perspective view of an embodiment of a first connecting piece (10) according to the invention; Fig.2A

[0023] [Fig. 2A] schematically represents an embodiment of a first single plate (1) according to the present invention; Fig.2B

[0024] [Fig. 2B] schematically represents an embodiment of a step of the bending steps of a first single sheet (1); Fig.2C

[0025] [Fig. 2C] schematically represents an embodiment of a step of the bending steps of a first single sheet (1); Fig.2D

[0026] [Fig. 2D] schematically represents a perspective view of the embodiment of a first joining piece (10) illustrated in Figure 1; Fig.2E

[0027] [Fig. 2E] schematically represents a perspective view of the embodiment of a first joining piece (10) illustrated in Figure 1; Fig. 3

[0028] [Fig. 3] represents a perspective view of an embodiment of a second connecting piece (20) according to the invention; Fig. 4A

[0029] [Fig. 4A] schematically represents an embodiment of a second single plate (2) according to the present invention; Fig. 4B

[0030] [Fig. 4B] schematically represents an embodiment of a bending step of a second single sheet (2) of the embodiment of a second joining piece (20) illustrated in Figure 3; Fig.4C

[0031] [Fig. 4C] schematically represents an embodiment of a bending step of a second single sheet (2) of the embodiment of a second joining piece (20) illustrated in Figure 3; Fig. 4D

[0032] [Fig. 4D] schematically represents an embodiment of a bending step of a second single sheet (2) of the embodiment of a second joining piece (20) illustrated in Figure 3; Fig.4E

[0033] [Fig. 4E] schematically represents an embodiment of a bending step of a second single sheet (2) of the embodiment of a second joining piece (20) illustrated in Figure 3; Fig. 5

[0034] [Fig. 5] represents a perspective view of two other embodiments of a second connecting piece (20) according to the invention; Fig.6A

[0035] [Fig. 6A] schematically represents an embodiment of a second single plate (2) for forming one of the parts illustrated in Figure 5 according to the present invention; Fig.6B

[0036] [Fig. 6B] schematically represents an embodiment of a step of the bending step of the embodiment of the second single sheet (2) illustrated in Figure 6A of an embodiment of the second joining piece (20) illustrated in Figure 5; Fig.6C

[0037] [Fig. 6C] schematically represents an embodiment of a step of the bending step of the embodiment of the second single sheet (2) illustrated in Figure 6A of an embodiment of the second joining piece (20) illustrated in Figure 5; Fig.6D

[0038] [Fig. 6D] schematically represents an embodiment of a step of the bending step of the embodiment of the second single sheet (2) illustrated in Figure 6A of an embodiment of the second joining piece (20) illustrated in Figure 5; Fig.6E

[0039] [Fig. 6E] schematically represents an embodiment of a step of the bending step of the embodiment of the second single sheet (2) illustrated in Figure 6A of an embodiment of the second joining piece (20) illustrated in Figure 5; Fig.6F

[0040] [Fig. 6F] schematically represents an embodiment of a step of the bending step of the embodiment of the second single sheet (2) illustrated in Figure 6A of an embodiment of the second joining piece (20) illustrated in Figure 5; Fig. 7

[0041] [Fig. 7] represents a perspective view of an embodiment of a third connecting piece (30) according to the invention; Fig. 8A

[0042] [Fig. 8A] schematically represents an embodiment of a third single plate (3) according to the present invention; Fig.8B

[0043] [Fig. 8B] schematically represents a first step of the bending stage of the third single sheet (3) illustrated in Figure 8A; Fig.8C

[0044] [Fig. 8C] schematically represents a perspective view of the embodiment of a first third part sub-piece (30A) according to the present invention; Fig.8D

[0045] [Fig. 8D] schematically represents another perspective view of the embodiment of a first third part sub-piece (30A) according to the present invention; Fig.8E

[0046] [Fig. 8E] schematically represents an embodiment of a fourth single plate (4) according to the present invention; Fig.8F

[0047] [Fig. 8F] schematically represents an embodiment of a first step of the bending step of the fourth single sheet (4) illustrated in Figure 8E; Fig.8G

[0048] [Fig. 8G] schematically represents a perspective view of the embodiment of a second third part sub-piece (30B) according to the present invention; Fig.8H

[0049] [Fig. 8H] schematically represents an embodiment of a last step of the assembly step of the third joining piece (30) illustrated in Figure 7; Fig.8I

[0050] [Fig. 8I] schematically represents a perspective view of an embodiment of the third connecting piece (30); Fig.9

[0051] [Fig. 9] represents a perspective view of an embodiment of a fourth connecting piece (40) according to the invention; Fig. 10A

[0052] [Fig. 10A] schematically represents the embodiment of a fourth single plate (4) according to the present invention, illustrated in; Fig.10B

[0053] [Fig. 10B] schematically represents another embodiment of a fourth single plate (4) according to the present invention; Fig.10C

[0054] [Fig. 10C] schematically represents a perspective view of a first fourth-piece sub-piece (40A) and a second fourth-piece sub-piece (40B) according to the invention; Fig. 10D

[0055] [Fig. 10D] schematically represents an embodiment of a last step of the assembly step of the embodiment of the fourth joining piece (40) illustrated in Figure 9; Fig.10E

[0056] [Fig. 10E] schematically represents another perspective view of the embodiment of the fourth connecting piece (40) illustrated in Figure 9; Fig. 11

[0057] [Fig. 11] represents a perspective view of an embodiment of a use of the first connecting piece (10) according to the present invention; Fig. 12

[0058] [Fig. 12] represents a perspective view of an embodiment of another use of the first connecting piece (10) and the second connecting piece (20) according to the present invention; Fig. 13

[0059] [Fig. 13] represents a top perspective view of the same embodiment of use illustrated in Figure 12; and Fig. 14

[0060] [Fig. 14] represents a perspective side view of another embodiment of a use according to the invention. Description of the Forms of Implementation

[0061] The present invention relates to a set of connecting pieces for structural tubes with non-circular cross-sections, such as rectangular or square cross-sections. The connecting pieces of the present invention are made from sheet metal of the same thickness as the structural metal tubes to be joined, where the sheet metal undergoes cutting, drilling, stamping, bending, and / or assembly, without using any welding or brazing technique. The set of connecting pieces of the present invention comprises, in a first embodiment, a first L-shaped connecting piece and a second parallelepiped-shaped connecting piece, one of whose ends is closed. The sheet metal of the second connecting piece is drilled in the area that, after bending, will become the closed end of the second connecting piece, as can be seen in the figures attached to this application.

[0062] After undergoing the cutting, drilling, and bending steps, the first and second joining pieces can preferably join metal structural tubes internally, through friction, since the equivalent outer diameter of the joining pieces of the invention is slightly smaller than the equivalent inner diameter of the structural tubes to be joined. For example, for a square-section structural tube with a standard dimension of 80 x 80 mm, the external dimension of the square cross-section of the joining pieces according to the invention that will join said structural tubes will be 76 x 76 mm. To join structural tubes of other dimensions, the dimensions of the joining pieces of the present invention will be adapted proportionally.

[0063] Details concerning examples of joining structural tubes with the joining pieces of the present invention will be given in relation to the following figures.

[0064] The set of structural tube joints may also comprise a third T-shaped joint and a fourth open-ended parallelepiped tube-shaped joint. The third and fourth joints each comprise two sub-pieces. Each sub-piece is made from sheet metal with a thickness identical to that of the wall of the structural tube to be joined and undergoes cutting, stamping, and bending, and in certain embodiments, drilling. The two sub-pieces of each of the third and fourth joints are then assembled together. Friction elements, which are reliefs produced during the stamping stage, fit between the two sub-pieces of each third and fourth joint, as illustrated in the figures and described below.

[0065] The invention also relates to the production process for these parts, which comprises the five steps mentioned above. The cutting, drilling, stamping, bending, and assembly steps utilize conventional methods existing in the art, which a person skilled in the art will understand. For example, the cutting step can be performed with a mechanical tool, laser, water jet, or other known process. The stamping step can be performed with a press or a die. The drilling step can be performed using a conventional sheet metal drilling tool, such as a mechanical drill. The bending step can be performed using a conventional sheet metal molding, forming, or profiling process. The assembly of the parts can be performed manually.

[0066] The invention also relates to the use of the set of joining parts of the invention in structures of preferably metallic structural tubes.

[0067] The figures will be described below to describe the embodiments of the present invention, which also illustrate examples of application of the present invention.

[0068] Figure 1 represents a perspective view of an embodiment of a first joining piece (10) according to the invention for joining structural tubes of non-circular cross-section, for example of square cross-section. The first joining piece (10) shown in Figure 1 has the shape of an L comprising a first arm of L, or first arm of first piece (11), and a second arm of L, or second arm of first piece (12). The first (11) and second (12) arms of first piece are represented with identical lengths, but may also have different lengths. The first arm of first piece (11) and the second arm of first piece (12) make an angle a with each other. This angle is comprised in the range of 10º to 170º, preferably of 30º to 150º, more preferably of 45º to 135º and, in the most preferred form shown in Figure 1, the angle a is approximately 90º.

[0069] The first (11) and second (12) arms of the first piece join at an elbow as shown in Figure 1 and as in a letter L, and terminate, respectively, at a first arm end (111) and a second arm end (121) which are both open. The first arm ends (111) and second arm ends (121) are open as is the entire piece, which is hollow. The first joining piece (10) is an integral piece obtained from a single first plate (1) which will be discussed in relation to Figure 2A.

[0070] The first joining piece (10) has a wall thickness that is equal to the wall thickness of the preferably metal structural tubes of square section (500), shown, for example, in Figure 12, which will be discussed below. The first joining piece (10) serves to join two preferably metal structural tubes of square section (500), which have a slightly larger square cross-sectional area, in a proportion equivalent to the following example: for a structural tube of square cross-sectional area of ​​80 x 80 mm, the outer dimension of the cross-sectional area of ​​each of the first arm of first piece (11) and second arm of first piece (12) would be 76 x 76 mm.In this way, when the first joining piece (10) is inserted inside the preferably metallic structural tubes (500), with the first arm of the first piece (11) being inserted into one structural metallic tube (500) and the second arm of the first piece (12) into the other structural metallic tube (500), it remains attached by friction to the inside surface of the preferably metallic structural tubes (500) that it is going to join.

[0071] Preferably metallic structural tubes (500) are not part of the present invention, as metallic structural tubes (500) and other materials already exist on the market.

[0072] The first connecting piece (10) may comprise holes (not shown) on one of its surfaces in order to receive fastening elements, for example screws, for fastening another connecting piece, for example a second connecting piece (20) according to the invention. An example of a fastening between an embodiment of a first connecting piece (10) and an embodiment of a second connecting piece (10) according to the invention is illustrated in Figure 13, which will be discussed below.

[0073] Figure 2A schematically represents an embodiment of a first single sheet (1) according to the present invention. The first single sheet (1) is made of a metallic material and has a thickness equal to the thickness of the preferably metallic structural tubes (500) that the first joining piece (10) will join, wherein the first joining piece (10) is obtained from the first single sheet (1) illustrated in Figure 2A.

[0074] The first single sheet (1) shown in Figure 2A is cut to the shape shown, i.e. from a rectangular sheet, from which a first square cross-section joining piece (10) is obtained, through cutting, drilling and bending steps. The dashed lines (98) represent bending lines, i.e. lines along which the bending of the first single sheet (1) will be applied, and the dotted lines (99) represent cutting lines, i.e. lines along which a cut will be applied to the first single sheet (1). The first single sheet (1) is subjected, through the production process according to the invention, to cutting, drilling and bending steps, in order to obtain a first joining piece (10) that remains integral, without the need for welding. The first joining piece (10) is then ready to use for joining metal structural tubes (500), as will be described below with reference to the remaining figures.

[0075] Figure 2B and Figure 2C illustrate steps of the bending step of the first joining piece (10) from the first single sheet (1), already cut, according to the production process of the invention. In Figure 2B is illustrated the first single sheet (1) after the cutting step and after the first steps of the bending step, in which the illustrated shape is produced in which in certain embodiments the first single sheet is subjected to a bending step to produce an embodiment of a first joining piece (10). In Figure 2B are illustrated the dashed lines (98) along which the first single sheet (1) will be subjected to bending. The solid lines (981) represented in Figure 2B illustrate lines along which steps of the bending step of the first single sheet (1) were applied.

[0076] Figure 2C illustrates subsequent steps of the bending stage to which the first single sheet (1) is subjected. Also in this Figure 2C are illustrated solid lines (981) along which steps of the bending stage were applied. The tabs (89) produced in the bending stage will play an important role in the production of the first joining piece (10) which cooperate with the remaining steps of the bending stage to dispense with bolts, welding or other technologies or techniques to hold the first joining piece (10) in the desired shape.

[0077] Figure 2D illustrates a perspective view of the first joining piece (10) after the bending step has been completed. Figure 2D shows that on the outer side walls of the first joining piece (10) there is a double layer (88) in which the sheet metal is superimposed, and Figure 2D also shows that the tabs (89) are folded into the interior of the double layer (88), thus ensuring the stability of the first single piece (10) when assembled. With this bending step, the side walls of the pieces become stronger and thicker, as their sides are now composed of more than one layer of sheet metal. The first arm of the first piece (11) and the second arm of the first piece (12) are intended to be inserted inside the structural tubes (500), preferably made of metal, already mentioned, in order to join them at a right angle to each other, in the embodiment of the first joining piece (10) shown in Figure 2D.

[0078] Figure 2E shows another perspective view of the first joining piece (10), in which one can also see the tabs (89) sandwiched between the double layer (88) of sheet metal on the outer side walls of the first joining piece (10), which is thus finished and ready for use, without the need for any subsequent operation to guarantee its integrity, such as welding.

[0079] In this way, the cutting and bending steps according to the invention produce a first joining piece that is smooth and uniform on the outer surfaces, having dimensions such that, through friction, it allows fitting inside structural tubes (500), as will be explained in more detail below.

[0080] Figure 3 illustrates a perspective view of an embodiment of a second connecting piece (20) according to the invention. The second connecting piece (20) has a tubular shape of non-circular cross-section, for example of rectangular cross-section or square cross-section, as illustrated in Figure 3, in which one end of the second connecting piece (20) is open (212) and the other end is closed (211) and forms an angle with the tubular walls of the second connecting piece (20), in which in the embodiment of Figure 3 the angle is 90º. The closed end (211) comprises holes (21) that receive fastening elements of the second connecting piece (20). The number of holes (21) that the closed end (211) comprises may be one hole (21), two holes (21), three or more holes (21), depending on the cross-sectional dimensions of the second connecting piece (20) and also depending on the length of the frame tubes (500) that are intended to be joined by the second connecting piece (20).In the preferred embodiment illustrated in Figure 3, the closed end (211) comprises four holes (21). The arrangement of the holes (21) in the closed base (211) of the second joining piece (20) depends on the configuration of the structure to be created. For example, in the use illustrated in Figure 12, which will be discussed in greater detail below, the holes (21) preferably assume the arrangement illustrated in Figure 3 and Figure 4A.

[0081] For different uses of the second connecting piece (20), for example, where the second connecting piece (20) is applied vertically, the arrangement of the four holes (21) may be close to the four vertices of the closed end (211) (arrangement not shown). In other words, the location and arrangement of the holes (21) depends on the stresses present in the structure to which the second connecting piece (20) is intended.

[0082] The fastening elements used to fasten the second joining piece (20) may be screws, or they may be other fastening elements available on the market and suitable for fastening the second joining piece (20), as a person skilled in the art will understand. The second joining piece (20) may be fastened, through its closed end (211) and said fastening elements, to another joining piece of the present invention. For example, the second joining piece (20) may be fastened to a first joining piece (10) according to the present invention, as is well illustrated in Figures 12, 13 and 14, which will be discussed later in this application.

[0083] Figure 4A schematically illustrates an embodiment of a second single sheet (2) according to the present invention. In a similar manner to that described above for the first single sheet (1) illustrated in Figure 2A, the second single sheet (2) is made of a metallic material and has a thickness identical to the thickness of the preferably metallic structural tubes (500) that the second joining piece (20) will join, wherein the second joining piece (20) is obtained from the second single sheet (2) illustrated in Figure 4A.

[0084] The second single sheet (2) shown in Figure 4A is cut to the shape shown, i.e., from a sheet that may be rectangular or square, a second joining piece (20) with a cross-section, for example, square, is obtained from the cutting and bending steps according to the invention. The second single sheet (2) is also subjected to a drilling step, as will be evident to a person skilled in the art. The dashed lines (98) represent lines that will be subjected to the bending step and the dotted lines (99) represent lines that will be subjected to a cutting step. The second single sheet (2) is subjected, through the production process according to the invention, to cutting, drilling and bending steps, in order to obtain a second joining piece (20) that remains integral, without the need for welding. The second joining piece (20) is ready to use for joining metal structural tubes (500), as will be described below with reference to the remaining figures.

[0085] Figures 4B, 4C, 4D and 4E illustrate the steps of the bending stage to obtain the second joining piece (20) from the second single sheet (2), already cut, in accordance with the production process of the invention.

[0086] Figure 4B shows the second single sheet (2) after the cutting step by the dotted lines (99) shown in Figure 4A, followed by the drilling and bending steps by the dashed lines (98), shown in the following figures. Figure 4B also shows the holes (21) to receive the fastening elements already discussed above.

[0087] Figure 4C illustrates steps of the bending stage carried out along the solid lines (981) to which the second single sheet (2) is subjected. Figure 4C also illustrates the holes (21) already discussed above.

[0088] Figure 4D illustrates another step in the bending stage for producing the second joining piece (20).

[0089] Figure 4E represents the embodiment of the second joining piece (20) illustrated in Figure 3, after completion of the bending step according to the process of the present invention. In the illustrated embodiment, the second joining piece (20) according to the invention presents triple side walls (87), in which three layers of sheet metal are superimposed and confer the same effects already discussed for the double layer (88) obtained in the first joining piece (10).

[0090] Figure 5 represents perspective views of two other embodiments of the second joining piece (20), in which the angle b between the closed end (211) and the tubular walls of the second joining piece (20) is different from 90º, and the closed end (211) has an oblique orientation in relation to the tubular walls of the second joining piece (20), also comprising holes (21). This oblique orientation may correspond to a value of the angle b between 10º and 170º, preferably from 30º to 150º, and more preferably the angle b belongs to the range from 45º to 135º, in which the angle b most suitable for the structure to be constructed with the structural tubes (500) of non-circular cross-section, for example of square cross-section, which the second joining piece (20) will join, after being fixed to another joining piece according to the invention, for example, to the first joining piece (10), is selected.Since the description of Figure 5 will otherwise be identical to the above description of Figure 3, it will not be described in greater detail here.

[0091] Figure 6A schematically illustrates another embodiment of a second single sheet (2) according to the present invention, from which one of the embodiments represented in Figure 5 can be obtained. In the second single sheet (2) of Figure 6A, the oblique cuts (66) determine the inclination of the closed end (211) relative to the tubular walls of non-circular cross-section of the second joining piece (20), that is, they determine the angle b.

[0092] As explained for Figure 4A, the second single sheet (2) represented in Figure 6A, is subjected to a cutting step along the dotted lines (99) and to bending step steps along the dashed lines (98).

[0093] As with Figures 4B, 4C, 4D and 4E, Figures 6B, 6C, 6D and 6E also illustrate the steps of the bending stage of the second single sheet (2) of Figure 6A in an identical manner and will therefore not be described in greater detail here. In Figure 6F, however, there is a final step that applies only to the embodiments of the second joining piece (20) in which the angle b is different from 90º. In Figure 6E, the unevenness between one of the layers of the triple layer (87) of sheet metal of the second single sheet (2) is visible after the preceding bending steps. In order for the second joining piece (20) to have the edges of the open end (212) at the same level, it is necessary to carry out the last step of the production stage, in which the inclination of the closed end (211) defined by the angle b different from 90º is obtained, and in which the edges of the open end (211) are leveled, thus obtaining one of the embodiments of the second joining piece (20) illustrated in Figure 5.

[0094] Figure 7 represents a perspective view of an embodiment of a third joining piece (30) according to the invention for joining structural tubes of non-circular cross-section, for example of square cross-section. The third joining piece (30) shown in Figure 7 has the shape of a T comprising a first T arm, or first third piece arm (31), and a second T arm, or second third piece arm (32). The first (31) and second (32) third piece arms are represented with different lengths, but may also have identical or equal lengths. The first third piece arm (31) and the second third piece arm (32) are substantially perpendicular to each other.

[0095] The first (31) and second (32) third piece arms join at a central area of ​​the first third piece arm (31) as illustrated in Figure 7, and as in a letter T.

[0096] The first third-piece arm (31) has two open ends (311, 312). The second third-piece arm (32) terminates, on the side opposite to the side where it joins the first third-piece arm (31), in an open end (321). As in the parts described above, that is, the first joining piece (10) and the second joining piece (20); the third joining piece is hollow, tubular, of non-circular cross-section, for example, of rectangular or square cross-section. The third joining piece (30) is obtained from a third single plate (3) and a fourth single plate (4) which are assembled as will be discussed below.

[0097] Figure 8A schematically represents an embodiment of a third single plate (3) according to the present invention, from which a first sub-piece of the third joining piece (30A) will be obtained which, together with a second sub-piece of the third joining piece (30B) fitted therein, will give rise to the embodiment of the third joining piece (30) represented in Figure 7.

[0098] The third single plate shown in Figure 8A is cut into a suitable shape, for example, into the shape shown in Figure 8A, which may resemble three side-by-side and uneven rectangles. Similar to what has already been explained previously for the other joining parts of the invention, the dotted lines (98) represent lines that are intended to receive the bending steps and the dotted lines (99) are intended to receive a cut in the third single plate (3). Preferably before the bending step, the third single plate (3) is subjected to a stamping step, in which friction elements (33) are produced, the location of which is marked in Figure 8A, but in other embodiments of the invention, the friction elements (33) may be placed in other suitable locations of the third single plate (3).

[0099] Figure 8B schematically represents a first step of the bending stage of the third single sheet (3) illustrated in Figure 8A, in which the solid lines (981) have already been subjected to a first bending step and the dashed lines (98) will subsequently still be subjected to a bending step. Figure 8B also illustrates the friction elements (33) obtained by the stamping stage.

[0100] Figures 8C and 8D show two perspective views of a first third-piece subpiece (30A) obtained from the third single plate (3), in which friction elements (33) are intended to come into contact with friction elements (33) of a second third-piece subpiece (30B), in a later assembly step. In the steps of the bending step, the pressure exerted on the plate will contribute to an optimized fit between the first (30A) and second (30B) third-piece subpieces, as will be seen in relation to Figure 8H. The first third-piece subpiece (30A) has open ends as illustrated and discussed in relation to Figure 7, and also has the lower area of ​​the first third-piece arm (31) open in which the second third-piece subpiece (30B) will be received as will be seen below.

[0101] Figure 8E schematically illustrates an embodiment of a fourth single sheet (4) according to the present invention. In a similar manner to that described above for the first single sheet (1), for the second single sheet (2) and for the third single sheet (3), the fourth single sheet is made of a metallic material and has a thickness identical to the thickness of the preferably metallic structural tubes (500) that the third joining piece (30) will join, wherein a second third piece subpiece (30B) is obtained from the fourth single sheet (4).

[0102] The fourth single sheet (4) shown in Figure 8E is cut in the shape shown, that is, from a sheet that may be, for example, rectangular. From it, a second sub-piece of a third piece (30B) with a cross-section, for example, square, will be obtained, through the aforementioned stamping steps, for producing friction elements (33), bending along the dashed lines (98), and assembly, according to the invention.

[0103] Figure 8F illustrates steps of the bending stage, in which bending was performed on solid lines (981).

[0104] Figure 8G illustrates a second sub-piece of the third part (30B) after the bending step and ready to be subjected to an assembly step in order to obtain an embodiment of the third joining part (30) according to the invention.

[0105] Figure 8H represents the assembly step of the third joining piece (30), in which the second third piece subpiece (30B) is inserted inside the first third piece arm (31) of the first third piece subpiece (30A), as shown by the arrow illustrated in Figure 8H. The friction elements (33) provided in both the first (30A) and second (30B) subpieces ensure the friction fit between them, thus forming a stable, robust and resistant third joining piece (30), ready to join three structural tubes (500), inside which the first third piece arm (31) and the second third piece arm (32) will be inserted, in which the first third piece arm (31) joins two tubes (500), with a structural tube (500) entering through each end (311, 312) of the first third piece arm (31) (not shown).

[0106] Figure 8I schematically illustrates a perspective view of an embodiment of the third connecting piece (30) after completion of the assembly step. Also in this case, the side walls have a double layer (88) as shown, wherein the outer layer of one double layer side continues extending to the inner layer of the double layer of the opposite wall of the second third piece arm (32). This double layer has the function and advantages discussed above for the other parts according to the invention and therefore will not be discussed here in greater detail.

[0107] Figure 9 represents a perspective view of an embodiment of a fourth joining piece (40) according to the invention, comprising two open ends (411, 412). This fourth joining piece (40), although similar to the second joining piece (20) but with both ends open, is obtained from two single fourth plates (4) and not from just one single plate. The fourth joining piece (40) is also shown comprising friction elements (33).

[0108] Figure 10A schematically represents the embodiment of a fourth single plate (4) according to the present invention, also illustrated in, showing friction elements (33) located in an area away from the dashed lines (98) of the fourth single plate (4).

[0109] Figure 10B schematically illustrates a fourth single plate (4) according to the present invention, in which the friction elements (33) were stamped in an area closer to the central section, that is, closer to the dashed lines (98) where the steps of the bending stage will be applied.

[0110] Both fourth single sheets (4) illustrated in Figures 10A and 10B are subjected to the stamping step, to produce the friction elements (33) already discussed, and are then subjected to the bending step in a manner identical to that described for the fourth single sheet (4) in Figure 8E.

[0111] Figure 10C illustrates a first fourth-piece sub-piece (40A) and a second fourth-piece sub-piece (40B) obtained from the two fourth single sheets (4) illustrated in Figures 10A and 10B, in which it is visible that the friction elements (33) are placed in different positions in the two sub-pieces (40A, 40B).

[0112] Figure 10D illustrates the assembly step of the fourth joining piece (40), in which the second fourth piece subpiece (40B) receives inside and facing itself the first fourth piece subpiece (40A), as shown by the arrow illustrated in Figure 10D. The friction elements (33) provided in both the first (40A) and second (40B) fourth piece subpieces ensure the friction fit between them, thus forming a stable, robust and resistant fourth joining piece (40), ready to join structural tubes (500), into which the fourth piece (40) will be inserted (not shown).

[0113] Figure 10E schematically illustrates a perspective view of an embodiment of the fourth connecting piece (40) after completion of the assembly step. In this case, too, the side walls have a double layer (88) opposite each other and friction-fitted via friction elements (33). This double layer has the function and advantages discussed above for the other parts according to the invention and will therefore not be discussed in greater detail here. The fourth connecting piece can join two structural tubes (500) that lie butt to each other and can be bolted to the fourth connecting piece (40) to obtain better structural results (not shown).

[0114] Figure 11 represents a perspective view of an embodiment of a use of the first joining piece (10) according to the present invention. In this Figure it can be seen that the first joining piece (10), of non-circular cross-section, that is, of square cross-section, has its arms inserted, each one, inside two structural tubes (500), also of non-circular cross-section, for example, of square cross-section with an area slightly greater than the cross-sectional area of ​​the first joining piece (10), as already illustrated in the example above, for a structural tube (500) of square cross-section of 80 x 80 mm and wall thickness of 2 mm. Figure 11 represents a phase of assembly of the structural tubes (500) in the first joining piece (10), in which after completion of the assembly in the direction represented by the arrows in Figure 11, the first joining piece (10) becomes invisible inside the tubes (500).

[0115] Figure 12 represents an embodiment of use of the present invention, in which a second joining piece (20) has been fixed by fasteners, for example, it has been screwed onto the elbow formed by the joining of the pipes (500) and the first joining piece (10) inside it, as discussed in relation to Figure 11. In other words, the fasteners, for example, screws, when tightened in the second joining piece (20) will also pierce the structural pipes (500) already joined by a first joining piece (10) according to the invention, and the first joining piece (10) itself that is inside it. In this way, greater security is provided in the structure, thus reinforcing the joining of the structural pipes (500) and it is also more aesthetically pleasing. A third structural pipe (500) is placed in a vertical position shown in Figure 12, being inserted in the direction of the arrow illustrated in the figure, so as to be joined to the other two pipes (500).The third structural tube (500) joined by the second joining piece (20) can be fixed, for example, by means of screws (not shown) to the second joining piece (20) to obtain better results and safety in the structure. The need to screw the tubes (500) depends on the size of the structure and the stresses it must withstand.

[0116] Figure 13 shows a top perspective view of the same embodiment of use illustrated in Figure 12, in which the fastening screws of the second connecting piece (20) to the structural tubes joined by a first connecting piece (10) according to the invention are visible. The second connecting piece (20) is also visible inside the structural tube (500) shown vertically in Figure 12.

[0117] Figure 14 represents a perspective side view of another embodiment of a use according to the invention, in which another second connecting piece (20) is fixed by means of screws, for example, on the opposite side to the second connecting piece (20) visible in Figure 12, forming the structure of Figure 13, in which a fourth structural tube (500) with the end cut obliquely has been inserted onto this other second connecting piece (20), which is invisible in Figure 13.

[0118] Starting from the structure created in any of Figures 11, 12, 14, it is possible to build any structure with structural tubes (500), preferably metallic, of non-circular cross-section, for example, of square cross-section, existing on the market, by using any of the joining pieces (10, 20, 30, 40) according to the invention and by means of the production process thereof, including cutting, stamping, drilling, bending and / or assembly steps, as defined by the appended claims. A structure built with a set of parts of the invention can be easily disassembled and both the structural tubes (500) used and the joining pieces of the invention themselves can be reused, thus contributing to a cleaner environment and less waste, especially with regard to non-permanent structures.

[0119] In a preferred embodiment of a first aspect, the invention relates to a set of connecting pieces of structural tubes (500) of non-circular cross-section comprising:

[0120] - at least one first L-shaped connecting piece (10) comprising a first first piece arm (11) and a second first piece arm (12) wherein the first (11) and second (12) first piece arms are tubular, have a non-circular cross-section and are of the same length or are of different lengths and the first (11) and second (12) first piece arms form an angle α between themselves and the first first piece arm (11) has an open end (111) and the second first piece arm (12) has an open end (121); and

[0121] - at least one second connecting piece (20) in the shape of a tube with a non-circular cross-section, said second connecting piece (20) comprising a closed end (211) and an open end (212) and in which the surface of the closed end (211) forms an angle b with one of the walls of the second connecting piece (20) and the closed end (211) comprises holes (21) which receive fastening elements;

[0122] in which the first joining piece (10) is integral, obtained from a first single sheet (1) and the second joining piece (20) is integral, obtained from a second single sheet (2), in which both the first (1) and second (2) sheets have a thickness equal to the thickness of preferably metallic tubes of non-circular cross-section joined by the first joining piece (10) and second joining piece (20) and in which the second joining piece (20) is fixed to an outer surface of the first joining piece (10) by means of fastening elements inserted in the holes (21); in which this fixing is direct or is made through a structural tube wall (500).

[0123] In another embodiment of the first aspect, the set of non-circular cross-section structural tube joining pieces (500) of the invention additionally comprises:

[0124] - at least one third T-shaped connecting piece (30) comprising a first third piece arm (31) and a second third piece arm (32) wherein the first (31) and second (32) third piece arms are tubular, have a non-circular cross-section, and are of the same length or are of different lengths and the first (31) and second (32) arms form a perpendicular angle between themselves and the first third piece arm (31) comprises a first third piece open end (311) and a second third piece open end (312) and the second third piece arm (32) comprises a third third piece open end (321);

[0125] wherein the third joining piece (30) is constituted by a first third piece subpiece (30A) and a second third piece subpiece (30B), wherein each of the first subpiece (30A) and second subpiece (30B) are obtained from a third single sheet (3) and a fourth single sheet (4), respectively, wherein both the third (3) and fourth (4) sheets have a thickness equal to the thickness of the structural tubes (500) of non-circular cross-section that the third joining piece (30) joins and in which the second third piece subpiece (30B) fits inside the first third piece arm (31) fixing itself therein by friction.

[0126] In another embodiment of the first aspect, the set of non-circular cross-section structural tube joining pieces (500) of the invention further comprises:

[0127] - at least a fourth connecting piece (40) in tubular form with a non-circular cross-section, comprising two open ends;

[0128] wherein the fourth joining piece (40) is constituted by a first fourth piece subpiece (40A) and a second fourth piece subpiece (40B), wherein each of the first fourth piece subpiece (40A) and second fourth piece subpiece (40B) are each obtained from a fourth single sheet (4), wherein the fourth single sheet (4) has a thickness equal to the thickness of the structural tubes (500) of non-circular cross-section that the fourth joining piece (40) joins and wherein the second fourth piece subpiece (40B) fits inside the first fourth piece subpiece (40A) and is fixed therein by friction.

[0129] In another embodiment of the first aspect of the invention, the second joining piece (20) of the set of joining pieces of structural tubes (500) of non-circular cross-section is fixed to an external surface of the third joining piece (30) and / or to an external surface of the fourth joining piece (40) through fastening elements inserted in the holes (21); in which this fixing is direct or is made through a wall of structural tube (500).

[0130] In yet another embodiment of the first aspect of the invention, one or more plates of the set of structural tube joining pieces (500) of non-circular cross-section selected from the group consisting of: third single plate (3), fourth single plate (4) according to the invention comprise one or more friction elements (33) on their surface.

[0131] In yet another embodiment of the first aspect of the invention, the angle at which the first arm of the first piece (11) and the second arm of the first piece (12) form between themselves belongs to the range from 10º to 170º, preferably from 30º to 150º, and more preferably the angle a belongs to the range from 45º to 135º.

[0132] In yet another embodiment of the first aspect of the invention, the angle b that the closed end (211) makes with one of the walls of the second joining piece (20) belongs to the range from 10º to 170º, preferably from 30º to 150º, and more preferably the angle b belongs to the range from 45º to 135º.

[0133] In an embodiment of a second aspect, the invention relates to a process for producing at least one of the parts of the set of joining parts according to the first aspect of the invention, comprising the following steps:

[0134] a) cutting of one or more metal sheets selected from the group consisting of: first single sheet (1), second single sheet (2);

[0135] b) drilling of at least one metal sheet selected from the group consisting of: first single sheet (1), second single sheet (2), cut in step a), in which the drilling produces holes (21); and

[0136] c) bending of one or more metal sheets selected from the group consisting of: first single sheet (1), second single sheet (2), cut in step a), in which at least one of the group consisting of: first joining piece (10), second joining piece (20) is produced during the bending.

[0137] In preferred embodiments of the second aspect of the present invention, the process for producing the set of joining parts as defined in the first aspect of the invention comprises:

[0138] - in stage a) cutting, two or more metal sheets selected from the group consisting of: third single sheet (3), fourth single sheet (4) are additionally cut;

[0139] - in drilling step b), one or more metal sheets selected from the group consisting of: third single sheet (3), fourth single sheet (4) are additionally drilled;

[0140] - in bending step c), two or more metal sheets selected from the group consisting of: third single sheet (3), fourth single sheet (4) cut in step a) are additionally bent, in which at least two of the group consisting of: first sub-piece of third piece (30A), second sub-piece of third piece (30B), first sub-piece of fourth piece (40A), second sub-piece of fourth piece (40B) are additionally produced during bending;

[0141] and additionally comprises the following steps:

[0142] d) stamping of one or more metal sheets selected from the group consisting of: third single sheet (3), fourth single sheet (4) cut in step a), in which during stamping one or more friction elements (33) are produced towards the inside of the part for which the third single sheet (3) and / or the fourth single sheet (4) are intended; and

[0143] e) assembly of at least one of each of the sub-pieces of the group consisting of: first sub-piece of third piece (30A), second sub-piece of third piece (30B), in order to produce at least one third joining piece (30) in the shape of a T as defined in the first aspect of the invention, in which a second sub-piece of third piece (30B) fits inside a first sub-piece of third piece (30A) and is fixed therein by means of the friction generated by the friction elements (33) obtained in the stamping step d);

[0144] in which step d) of stamping is carried out before step c) of bending.

[0145] In other embodiments of the second aspect of the present invention, the process of producing the set of joining parts as defined in the first aspect of the invention further comprises, in the assembly step e):

[0146] - assembly of at least one of each of the sub-pieces of the group consisting of: first sub-piece of fourth piece (40A), second sub-piece of fourth piece (40B), in order to produce a fourth joining piece (40) as defined for the first aspect of the invention, in which the second sub-piece of fourth piece (40B) fits inside the first sub-piece of fourth piece (40A) and is fixed thereto by means of the friction generated by the friction elements (33) obtained in the stamping step d).

[0147] In a third aspect, the invention relates to a use of the set of joining parts according to the first aspect of the invention, produced by the process of the second aspect of the invention, in which the use is in the joining of two or more structural tubes (500), in which the structural tubes (500) can be made of metal or plastic, preferably the structural tubes (500) are made of metal, of non-circular cross-section that make up preferably metallic structures. Definitions

[0148] As used in this application, the term “substantially” followed by perpendicular, rectangular or quadrangular, for example, means that the elements referred to as substantially perpendicular make a right angle to each other, plus or minus 10%, and the elements referred to as rectangular, quadrangular, may approximate in at least 80% of their shape, to a rectangle or a square, respectively.

[0149] As used throughout this patent application, the term “or” is used in an inclusive rather than an exclusive sense, unless the exclusive sense is clearly defined in a specific situation. In this context, a sentence such as “X uses A or B” should be interpreted as including all relevant inclusive combinations, e.g., “X uses A,” “X uses B,” and “X uses both A and B.”

[0150] As used throughout this patent application, the indefinite articles “a” or an” should be interpreted generally as “one or more” and “an or more”, unless the meaning of a singular embodiment is clearly defined in a specific situation.

[0151] As presented in this description, the terms related to examples should be interpreted for the purpose of illustrating an example of something and not indicating a preference.

[0152] The subject matter described above is provided as an illustration of the present invention and should not be construed as limiting it. The terminology employed to describe specific embodiments of the present invention should not be construed as limiting the invention. As used in the description, the definite and indefinite articles, in their singular form, are intended to also include the plural forms, unless the context of the description explicitly indicates otherwise. It will be understood that the terms "comprise" and "include," when used in this description, specify the presence of the related features, elements, components, steps, and operations, but do not exclude the possibility of other features, elements, components, steps, and operations also being contemplated.

[0153] All changes, provided they do not modify the essential characteristics of the following claims, must be considered within the scope of protection of the present invention.

[0154] 1 – first single plate

[0155] 2 – second single plate

[0156] 3 – third single plate

[0157] 4 – fourth single plate

[0158] 10 – first joining piece

[0159] 11 – first arm of first piece

[0160] 12 - second arm of first piece

[0161] 111 – first arm open end of first piece

[0162] 121 - open end of second arm of first piece

[0163] 20 – second joining piece

[0164] 21 – holes for fastening elements

[0165] 211 – closed end of second piece

[0166] 212 - open end of second piece

[0167] 30 – third joining piece

[0168] 30A – first sub-piece of third piece

[0169] 30B – second subpiece of third piece

[0170] 31 – first arm of third piece

[0171] 32 – second arm of third piece

[0172] 33 – friction elements

[0173] 311 – first open end of third piece

[0174] 312 – second open end of third piece

[0175] 321 - third open end of third piece

[0176] 40 – fourth joining piece

[0177] 40A – first sub-piece of fourth piece

[0178] 40B – second subpiece of fourth piece

[0179] 411 – first open end of fourth piece

[0180] 412 - second open end of fourth piece

[0181] 66 – oblique cuts

[0182] 87 – triple side walls

[0183] 88 – double side walls

[0184] 89 – tabs

[0185] 98 – dashed lines

[0186] 981 – solid lines

[0187] 99 – dotted lines

[0188] 500 – structural metal tube

[0189] a – angle

[0190] b - angle

Claims

A set of structural tube joining pieces (500) of non-circular cross-section comprising:- at least one first L-shaped joining piece (10), comprising a first first piece arm (11) and a second first piece arm (12) wherein the first (11) and second (12) first piece arms are tubular, have non-circular cross-section and are of the same length or are of different lengths and the first (11) and second (12) first piece arms form an angle a between them and the first first piece arm (11) has an open end (111) and the second first piece arm (12) has an open end (121);and- at least one second joining piece (20) in the shape of a tube with a non-circular cross-section, said second joining piece (20) comprising a closed end (211) and an open end (212) and in which the surface of the closed end (211) forms an angle b with one of the walls of the second joining piece (20) and the closed end (211) comprises holes (21) receiving fastening elements; characterised in that the first joining piece (10) is integral, obtained from a first single sheet (1) and in that the second joining piece (20) is integral, obtained from a second single sheet (2), in which both the first (1) and second (2) single sheets have a thickness equal to the thickness of structural tubes (500) of non-circular cross-section joined by the first joining piece (10) and the second joining piece (20) and in which the second joining piece (20) is fixed to an outer surface of the first joining piece (10) by means of inserted fastening elements in the holes (21);where this fixation is direct or is made through a structural tube wall (500).; The set of structural tube joining pieces (500) of non-circular cross-section according to claim 1, further comprising:- at least one third T-shaped joining piece (30), comprising a first third piece arm (31) and a second third piece arm (32) wherein the first (31) and second (32) third piece arms are tubular, have non-circular cross-section, and are of the same length or are of different lengths and the first (31) and second (32) arms form a perpendicular angle to each other and the first third piece arm (31) comprises a first third piece open end (311) and a second third piece open end (312) and the second third piece arm (32) comprises a third third piece open end (321);characterized in that the third joining piece (30) is constituted by a first third piece subpiece (30A) and a second third piece subpiece (30B), in which each of the first third piece subpiece (30A) and second third piece subpiece (30B) are obtained from a third single sheet (3) and a fourth single sheet (4), respectively, in which both the third (3) and fourth (4) single sheets have a thickness equal to the thickness of the structural tubes (500) of non-circular cross-section that the third joining piece (30) joins and in which the second third piece subpiece (30B) fits inside the first third piece arm (31) fixing itself therein by friction.; The set of non-circular cross-section structural tube joining pieces (500) according to either of claims 1 or 2, further comprising:- at least one fourth joining piece (40) in tubular form of non-circular cross-section, comprising two open ends; characterised in that the fourth joining piece (40) is constituted by a first fourth piece sub-piece (40A) and a second fourth piece sub-piece (40B), wherein each of the first fourth piece sub-piece (40A) and second fourth piece sub-piece (40B) are each obtained from a fourth single sheet (4), wherein the fourth single sheet (4) has a thickness equal to the thickness of the non-circular cross-section structural tubes (500) that the fourth joining piece (40) joins and wherein the second fourth piece sub-piece (40B) fits inside the first fourth piece sub-piece (40A) and is fixed thereto by friction. The set of structural tube joining pieces (500) of non-circular cross-section according to any one of claims 1 to 3, characterized in that the second joining piece (20) is fixed to an outer surface of the third joining piece (30) and / or to an outer surface of the fourth joining piece (40) by means of fastening elements inserted in the holes (21); wherein this fixing is direct or is made through a structural tube wall (500). The set of structural tube joining pieces (500) of non-circular cross-section according to any one of claims 2 to 4, characterized in that one or more of the group consisting of: third single plate (3), fourth single plate (4) comprise one or more friction elements (33) on their surface. The set of structural tube joining pieces (500) of non-circular cross-section according to any one of claims 1 to 5, characterized in that the angle at which the first arm of the first piece (11) and the second arm of the first piece (12) form between themselves belongs to the range from 10º to 170º, preferably from 30º to 150º, and more preferably the angle a belongs to the range from 45º to 135º. The set of structural tube joining pieces (500) of non-circular cross-section according to any one of claims 1 to 6, characterized in that the angle b that the closed end (211) forms with one of the walls of the second joining piece (20) belongs to the range from 10º to 170º, preferably from 30º to 150º, and more preferably the angle b belongs to the range from 45º to 135º. Process for producing the set of joining pieces as defined in any one of the preceding claims, characterized in that it comprises the following steps: a) cutting one or more metal sheets selected from the group consisting of: first single sheet (1), second single sheet (2); b) drilling at least one metal sheet selected from the group consisting of: first single sheet (1), second single sheet (2), cut in step a), in which the drilling produces holes (21); and c) bending the one or more metal sheets selected from the group consisting of: first single sheet (1), second single sheet (2), cut in step a), in which during the bending at least one of the group consisting of: first joining piece (10), second joining piece (20) is produced, as defined in any one of claims 1 to 7. Process for producing the set of joining parts as defined in any one of claims 2 to 7, according to the previous claim, characterized in that:- in step a) of cutting, two or more of the metal sheets selected from the group consisting of: third single sheet (3), fourth single sheet (4) are additionally cut;- in step b) of drilling, one or more metal sheets selected from the group consisting of: third single sheet (3), fourth single sheet (4) are additionally drilled;- in step c) of bending, two or more metal sheets selected from the group consisting of: third single sheet (3), fourth single sheet (4) cut in step a) are additionally bent, in which during the bending at least two of the group consisting of: first sub-piece of third piece (30A), second sub-piece of third piece (30B), first sub-piece of fourth piece (40A), second sub-piece of fourth piece (40B) are additionally produced;and additionally comprise the following steps:d) stamping of one or more metal sheets selected from the group consisting of: third single sheet (3), fourth single sheet (4) cut in step a), in which during stamping one or more friction elements (33) are produced in the direction of the inside of the part for which the third single sheet (3) and / or the fourth single sheet (4) is intended; ee) assembling at least one of each of the sub-pieces of the group consisting of: first third-piece sub-piece (30A), second third-piece sub-piece (30B), so as to produce at least one third T-shaped joining piece (30) as defined in any one of claims 2 to 7, in which a second third-piece sub-piece (30B) fits inside a first third-piece sub-piece (30A) and is fixed thereto by means of the friction generated by the friction elements (33) obtained in stamping step d); in which stamping step d) is carried out before bending step c). Process for producing the set of joining pieces as defined in any one of claims 3 to 7, according to any one of claims 8 or 9, characterized in that:- the assembly step e) additionally comprises: assembling at least one of each of the sub-pieces of the group consisting of: first fourth piece sub-piece (40A), second fourth piece sub-piece (40B), so as to produce at least a fourth joining piece (40) as defined in any one of claims 3 to 7, in which the second fourth piece sub-piece (40B) fits inside the first fourth piece sub-piece (40A) and is fixed therein by means of the friction generated by the friction elements (33) obtained in the stamping step d). Use of the set of joining parts as defined in any one of claims 1 to 7, in which the parts are produced as defined in any one of claims 8, 9 or 10, characterized in that the use is in the joining of two or more structural tubes (500), preferably metallic structural tubes (500), of non-circular cross-section that make up structures.

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