EP3068558B1 - Method for producing a steel section, in particular a steel girder - Google Patents

Description

The invention lies in the field of steel processing and steel production, in particular the production of steel beams. The invention relates to a method for producing a steel beam, which comprises the steps: providing a metal workpiece, in particular a strip steel workpiece, which preferably has a thickness of at least 5 mm, forming a weakening in the area of an intended bend in the metal workpiece and bending the metal workpiece to create a bend in the metal workpiece. The invention also relates to a steel beam.

Processes for the production of steel beams are known in principle from the prior art. Steel profiles are often produced in steel mills by continuous casting, hot rolling or cold rolling. Also known are steel profiles that are produced by massive forming of steel blanks. From the WO 2012/150352 A2 , which forms the basis for the preambles of claims 1 and 6, a method for the production of a steel profile is known, in which a weakening is formed in the region of an intended bend of the workpiece before the bending of the workpiece.

Against this background, it is the object of the present invention to provide an improved method for producing a steel beam and an improved steel beam.

According to the invention, this object is achieved by a method for producing a steel beam according to claim 1 .

The invention is based on the finding that the known methods for producing steel beams have several disadvantages. On the one hand, the known methods for producing steel profiles are energy-intensive, labor-intensive and associated with high set-up and start-up costs. This results in high minimum order quantities and comparatively long delivery times, so far-sighted production planning and high stock levels are necessary in order to be able to react flexibly to customer orders.

An advantage of the method according to the invention lies in the fact that an autonomous, flexible and fully automatic production of steel profiles, preferably directly from a coil or a strip steel roll or starting from flat steel workpieces, is made possible. In addition, production costs are kept low by comparatively low set-up costs, low labor costs and low material loss. The needs-based and timely production achieved when using the process also enables low storage costs. The process is also energy-efficient, clean and environmentally friendly. Energy is saved in particular when processing thick-walled steel.

Another essential advantage of the invention is that steel beams can be manufactured with great precision. The formation of the weakening means that the behavior of the workpiece when bending can be predicted. By connecting two edge areas of the bent metal workpiece, a closed steel profile is created, which can be used as a steel beam.

The present invention also includes the finding that the steel girders of the present invention, which are preferably designed as hollow steel profiles, offer the right cross-section for every load case. The standard industry requirements, in particular those under the English terms "made to measure (load)" (in German: manufactured for the load case / tailor-made) and "mass customization " (in German: customer-specific mass production) known requirements are met.

Furthermore, the present invention includes the finding that the steel beams according to the invention, which are preferably designed as steel hollow profiles, in particular the essentially square steel hollow profiles, give the architect more freedom in design due to their narrow outer radii, since, for example, profiles lying flat on one another only have relatively narrow joints.

In addition, the present invention also includes the finding that the sharp-edged inner edges of a steel girder, preferably designed as a steel hollow profile and more preferably as a square steel hollow profile, allow precisely fitting inserts such as connecting elements to be produced with relatively little effort.

The metal workpiece is preferably formed from a steel strip workpiece. The weakening of the workpiece preferably runs along an intended bend in the workpiece. More preferably, the weakening is formed by forming a recess in the workpiece. This represents a particularly expedient and simple variant for forming a weakening in the area of an intended bend in the workpiece. In the context of the present invention, the term notch is to be understood as meaning a recess which is formed in the workpiece in such a way that it has an open end, in particular directed to a bend inside.

The weakening after the bending is particularly preferably increased by welding, in particular laser welding, preferably by a laser hybrid welding method. By reinforcing a weakening provided for bending after bending, a steel profile with particularly high rigidity is produced. The welding preferably serves to completely close a recess that is partially closed during bending. In this case, for example, abutting ends of the recess of the workpiece can be undetachably connected by welding. In the context of the present invention, the term laser welding is to be understood as meaning the non-detachable connection of two ends of a steel profile using an optically focused laser beam with high intensity. More preferably, the welding is carried out by means of a focused laser beam, which is directed from the outside of the workpiece to the inside of the bend, in particular along a zero gap formed by the recess after bending, the focus of which is preferably within the workpiece. In the context of the present invention, the term zero gap is to be understood in such a way that the legs of the recess lie against one another after bending, e.g. B. have contact without forming a chemical bond. Basically, with a single bend in the workpiece, welding is from the bend outside of the workpiece to the The inside of the bend as well as from the inside of the bend to the outside of the bend is possible regardless of the bend angle. When manufacturing a steel profile, however, some bends cannot be welded starting from the inside of the bend, since individual bend insides or zero gaps are covered by adjacent strips of the workpiece and are therefore not accessible to a laser beam. In addition, the welding can be carried out particularly easily by means of a laser beam which is directed from the outside of the bend to the inside of the bend. A single focused laser beam is preferably used instead of an oscillating beam or two partial laser beams.

More preferably, a recess forming the weakening is provided in the workpiece, with the recess formed on a bent inner side of the workpiece being closed by welding, in particular laser welding, after bending. This specifies a method with which a recess, which is initially reduced in size during bending, is closed by welding to reinforce the steel profile. Legs which delimit a recess forming the weakening are even more preferably permanently connected. A weakening provided for the bending is thus additionally reinforced after the bending.

The bending is preferably carried out by free bending, swivel bending or die bending. More preferably, the workpiece is provided by unrolling a steel strip roll, in particular a coil. In the context of the present invention, the term coil is to be understood as meaning a coiled-up metal strip, for example in the form of a steel strip roll.

A recess is preferably made in a workpiece, which is designed as a strip steel blank, before bending, which recess is aligned transversely to the longitudinal direction of the strip steel blank and is open to a lateral boundary of the strip steel blank. The recess can be formed, for example, as a slit-like recess, which is introduced laterally into the strip steel blank, for example by means of a punching tool, a high-energy laser beam or a steel saw. The longitudinal direction of the strip steel blank is preferably the direction in which the strip steel blank moves during the manufacturing process, for example on a conveyor belt or a roller conveyor. In particular, this can also be the direction in which a steel strip unwound from a steel strip roll is fed to the assembly line. The recesses make it possible for work steps in the manufacturing process to be carried out in a first area of the strip steel blank without this having an effect on a second portion of the strip steel blank separated from the first portion by the recess. More preferably, the recess protrudes into the strip steel blank such that a bending moment in a first region of the strip steel blank, which delimits a first section of the recess, is not transferred to a second region of the strip steel blank, which delimits a second section of the recess. This achieves a considerable simplification of the manufacturing process of a steel profile when using strip steel blanks. The bends carried out according to the method according to the invention can be made without there being a need to completely separate individual sections of the strip steel blank from one another before bending. The recesses are each made with a specified depth in the strip steel blank in such a way that a bending moment in a first area of the strip steel blank is not transferred to a second area of the strip steel blank, but the two areas nevertheless remain connected in a specified section of the strip steel blank. In the manufacturing process of a steel profile according to the invention, the first area of the strip steel blank is located, for example, in a bending device, so that the workpiece can be bent therein. In this case, the recess serves to ensure that the bending is not transferred to a second area of the strip steel blank, which is still located in the weakening device, for example.

According to a preferred embodiment of the method according to the invention, the weakening, in particular a recess forming the weakening, is formed by milling. Within the scope of the invention, it has been shown that problems occur during bending in the case of a recess formed by rolling or embossing. Because, for example, when rolling a recess, material shifts occur that can lead to the workpiece breaking during bending. In contrast, when milling, areas of the workpiece surrounding the recess are not or only slightly affected.

According to the method according to the invention, a recess forming the weakening has a W-shaped area before bending. Preferably, the W-shaped portion is formed in a central portion of the recess as viewed in a longitudinal direction of the workpiece. Two inner legs of the W-shaped area are preferably aligned at an angle of approximately 90° to one another. Forming the recess with a W-shaped area is particularly advantageous for forming the recess by milling, since
Disadvantages that occur when milling a V-shaped recess can be overcome.

According to a preferred further development of the embodiment mentioned above, a first beveled area follows the ends of the W-shaped area. In this case, two legs of the beveled area are preferably aligned at an angle of approximately 50° to 110°, in particular approximately 90°, to one another.

According to a further preferred development of the aforementioned development, the first beveled area transitions into a second beveled area, which preferably has a larger opening angle than the first beveled area. Two legs of the second beveled area preferably form the opening angle. Therefore, the two legs of the second beveled area are aligned at an angle to one another which is greater than the angle between the two legs of the first beveled area, in particular greater than 90°, particularly preferably about 122°. In the context of the present invention, the wording “transition into” is to be understood as a direct or indirect transition. The first beveled area preferably merges indirectly, in particular by means of a step, into the second beveled area. After bending, in particular in the case of a 90° bend, this creates a substantially U-shaped gap on the inside of the bend, which serves as protection against corrosion. The penetration depth of the weld can advantageously also be influenced by the U-shaped gap described above. Depending on the power of the laser beam source, it is thus possible to advantageously define the welding depth or component thickness in the edges via the U-shaped gap. The U-shaped gap can also be used to prepare the weld seam for another weld, for example MIG (metal inert gas welding), MAG (metal active gas welding), MSG (metal inert gas welding) or laser hybrid welding, which is then carried out from the inside is executed here.

In a further preferred embodiment of the method according to the invention, a curved recess section adjoins the ends of the W-shaped area of the recess or the ends of the first beveled area of the recess. After bending, the two curved recess sections together form a U-shaped gap on a bent inner side of the workpiece, which serves as protection against corrosion. Preferably, the curved recess portions extend from the ends of the W-shaped portion or from the Ends of the legs of the beveled area of the recess initially with a large curvature, which steadily decreases towards the end of the recess section.

According to a further preferred embodiment of the method according to the invention, steps b) and c) are carried out twice or four times, respectively, in order to provide a triangular or quadrangular support structure by step c).

The object mentioned at the outset is achieved according to a second aspect of the invention by a steel girder according to independent patent claim 6.

According to a preferred further development of the embodiment mentioned above, a first beveled area adjoins the ends of the W-shaped area of the recess.

According to a further preferred development of the aforementioned development, the first beveled area transitions into a second beveled area, which preferably has a larger opening angle than the first beveled area.

A further preferred embodiment of the steel profile comprises a first wall section, a second wall section, which extends from a first end of the first wall section and is oriented at an angle in the range of 30° to 150° to the first wall section, and a third wall section, extending from a second end of the first wall section and oriented at an angle in the range of 30° to 150° to the first wall section, an end of the first wall section and an end of the second wall section abutting for bonding. This embodiment preferably achieves a steel beam that is essentially triangular in cross section. More preferably, the angle between the first and second wall section and the angle between the first and third wall section is approximately 60°, in particular in the case of an embodiment with an equilateral triangular cross section.

Another preferred embodiment of the steel profile comprises a first, second and third wall section, wherein the second and third wall section each extend from the first wall section and are oriented at an angle of approximately 90° to the first wall section, a first connecting section which extends extending from the second wall portion and oriented at an angle of about 90° to the second wall portion, and a second connecting portion extending from the third wall portion and oriented at an angle of about 90° to the third wall portion, one end of the first connection portion and an end of the second connection portion abut each other for connection. The two connecting sections preferably form a fourth wall of the steel profile, which is aligned at an angle of approximately 90° to the second and third wall section. Seen in cross section, the steel profile is preferably closed and rectangular in shape. More preferably, the abutting ends of the second connecting portion are connected to each other by welding.

According to a particularly preferred embodiment of the steel profile, the end of the first connecting section has at least one groove, with the end of the second connecting section having at least one tongue which is designed to correspond to the groove. This creates a particularly simple and at the same time stable connection between the connecting sections. According to this embodiment, the tongue and groove connection is preferably formed along the longitudinal extension of the steel profile. More preferably, after bending the metal workpiece, the ends of the connecting portions are connected to each other by welding.

According to a preferred embodiment of the steel profile, the first and second connection sections are connected to one another by means of at least one dovetail connection. For this purpose, an essentially approximately dovetail-shaped spring of the first connecting section preferably engages in a corresponding recess of the second connecting section. A dovetail joint or a dovetail joint is preferably cut using laser beams, while a tongue and groove joint is preferably milled.

For advantages, design variants and design details of the steel profile described above and its developments, reference is made to the previous description of the corresponding method features.

Preferred embodiments of the invention will now be explained with reference to the drawings.

Fig. 1

einen Zwischenzustand eines Metall-Werkstücks für ein erstes Ausführungsbeispiel eines erfindungsgemäßen Stahlprofils in einer Seitenansicht,

Fig. 2

das in Fig. 1 gezeigte Metall-Werkstück in einer Draufsicht,

Fig. 3

das in den Figuren 1 und 2 gezeigte Metall-Werkstück in einer perspektivischen Ansicht,

Fig. 4

das erste Ausführungsbeispiel eines erfindungsgemäßen Stahlprofils in einer Seitenansicht,

Fig. 5

das in Fig. 4 gezeigte Stahlprofil in einer Draufsicht,

Fig. 6

das in den Figuren 4 und 5 gezeigte Stahlprofil in einer perspektivischen Ansicht,

Fig. 7

einen Abschnitt des Metall-Werkstücks gemäß dem ersten Ausführungsbeispiel eines erfindungsgemäßen Stahlprofils in einer Seitenansicht,

Fig. 8

den in Fig. 7 gezeigten Abschnitt des Metall-Werkstücks in einer Draufsicht,

Fig. 9

den in den Figuren 7 und 8 gezeigten Abschnitt des Metall-Werkstücks in einer perspektivischen Ansicht,

Fig. 10

einen Zwischenzustand eines Metall-Werkstücks für ein zweites Ausführungsbeispiel eines erfindungsgemäßen Stahlprofils in einer Seitenansicht,

Fig. 11

das in Fig. 10 gezeigte Metall-Werkstück in einer Draufsicht,

Fig. 12

das in den Figuren 10 und 11 gezeigte Metall-Werkstück in einer perspektivischen Ansicht,

Fig. 13

das zweite Ausführungsbeispiel eines erfindungsgemäßen Stahlprofils in einer Seitenansicht,

Fig. 14

das in Fig. 13 gezeigte Stahlprofil in einer Draufsicht,

Fig. 15

das in den Figuren 13 und 14 gezeigte Stahlprofil in einer perspektivischen Ansicht,

Fig. 16

einen Abschnitt des Metall-Werkstücks gemäß dem zweiten Ausführungsbeispiel des erfindungsgemäßen Stahlprofils in einer Seitenansicht

Fig. 17

den in Fig. 16 gezeigten Abschnitt des Metall-Werkstücks in einer Draufsicht,

Fig. 18

den in den Figuren 16 und 17 gezeigten Abschnitt des Metall-Werkstücks in einer perspektivischen Ansicht,

Fig. 19-28

weitere Ausführungsformen der Erfindung,

Fig. 29

eine Untersuchung der Firma "IWF Ingenieurbüro Uwe Großmann" vom 26. August 2013, und

Fig. 30

die Seite 2 der von "Steeltube Institute of North America" unter dem Titel "Hollow structural sections, column load tables" im Juli 1997 herausgebenden Broschüre.

The drawings show:

1

an intermediate state of a metal workpiece for a first embodiment of a steel profile according to the invention in a side view,

2

this in 1 shown metal workpiece in a top view,

3

that in the Figures 1 and 2 shown metal workpiece in a perspective view,

4

the first embodiment of a steel profile according to the invention in a side view,

figure 5

this in 4 shown steel profile in a top view,

6

that in the Figures 4 and 5 shown steel profile in a perspective view,

7

a section of the metal workpiece according to the first embodiment of a steel profile according to the invention in a side view,

8

the in 7 shown section of the metal workpiece in a plan view,

9

the in the Figures 7 and 8 shown section of the metal workpiece in a perspective view,

10

an intermediate state of a metal workpiece for a second embodiment of a steel profile according to the invention in a side view,

11

this in 10 shown metal workpiece in a top view,

12

that in the Figures 10 and 11 shown metal workpiece in a perspective view,

13

the second embodiment of a steel profile according to the invention in a side view,

14

this in 13 shown steel profile in a top view,

15

that in the Figures 13 and 14 shown steel profile in a perspective view,

16

a section of the metal workpiece according to the second embodiment of the steel profile according to the invention in a side view

17

the in 16 shown section of the metal workpiece in a plan view,

18

the in the Figures 16 and 17 shown section of the metal workpiece in a perspective view,

19-28

further embodiments of the invention,

29

an investigation by the company "IWF Ingenieurbüro Uwe Großmann" from August 26, 2013, and

30

page 2 of the brochure entitled "Hollow structural sections, column load tables" published by Steeltube Institute of North America in July 1997.

The in the Figures 1 to 18 illustrated embodiments are not true-to-scale illustrations. In particular, the depth of the Figures 4-6 and 13-15 shown steel profile 10 in the direction 20 of a bending edge 30 is not true to scale. In practical implementation, the steel profile, in particular for use as a steel girder, will be deeper than shown.

Figures 1, 2 and 3 show a side view, top view and perspective view of a metal workpiece in an intermediate state after it has been provided in a first method step A in the form of a strip steel workpiece with a thickness of at least 5 mm and after in a second method step B Recesses 3, 5, 7 and 9 were formed by milling in the area of an intended bend in the metal workpiece 1.

Figures 4, 5 and 6 show that in the Figures 1, 2 and 3 shown metal workpiece in a second intermediate state, after the metal workpiece 1 was bent four times in a method step C, namely in each case in the area of the recesses 3, 5, 7 and 9. In the second intermediate state, the metal workpiece 1 has a first wall section 11, a second wall section 13 and a third wall section 15. The second and third wall sections 13 and 15 extend from the first wall section 11 and are aligned at an angle of 90° to the first wall section 11 . In the second intermediate state, the metal workpiece 1 also has a first connecting section 17 which extends from the second wall section 13 and is aligned at an angle of 90° to the second wall section 13 . In addition, the metal workpiece 1 in the second intermediate state has a second connecting section 19 which extends from the third wall section 15 and is aligned at an angle of approximately 90° to the third wall section 15 . The ends of the first connection portion 17 and second connection portion 19 abut each other for connection. For this purpose, the second connecting section 19 has a spring 21 which is designed in the shape of a dovetail. The first connecting section 17 has a groove 23 designed to correspond to the spring. When the metal workpiece 1 is bent in the area of the recesses 3 and 9, the tongue 21 engages in the groove 23 and thus forms a connection between the connecting sections 17 and 19. The ends of the first connecting section 17 and second connecting section 19 are also connected by means connected by welding.

Figures 7, 8 and 9 Figure 13 shows a portion of a metal workpiece 1 in an intermediate state in which the recess 9 is shown prior to bending while the tongue 21 and groove 23 are engaged. the Figures 7, 8 and 9 serve to illustrate preferred angular dimensions of the metal workpiece. In practical use, the tongue 21 and groove 23 only engage when the metal workpiece 1 is bent in the area of the recesses 3 and 9 .

The recess 9 is in the viewing direction 7 viewed mirror-symmetrically to an axis 12 formed. The recess 9 has a W-shaped area 31 arranged mirror-symmetrically to the axis 12 and a first beveled area 33 . The first beveled area 33 merges into a second beveled area 35 via a step 34 . After bending C, the W-shaped portion 31 and the first tapered portion 33 each form a zero gap. The second tapered portion 35 forms a U-shaped groove after bending. Two legs 37 forming the first beveled portion 33 are oriented at an angle of about 90° to each other prior to bending C. Two legs 39 forming the second beveled portion 35 are oriented at an angle of about 122° to each other prior to bending.

The tongue 21 and groove 23 are essentially designed to correspond to one another. In a viewing direction of 7 Viewed from the lower region 51, the tongue 21 and the groove 23 are essentially in a form-fitting manner. In a viewing direction of 7 Viewed from the upper region 53, the groove 23 is beveled, so that a channel 55 is formed in a transition region between the tongue 21 and the groove 23. The channel 55 is preferably used on the one hand as a clearance via which the opposite leg is restricted and on the other hand preferably as a weld seam preparation for the subsequent welding or the butt joint with additional material, preferably for example by means of a laser hybrid welding process.

The in the Figures 10 to 18 Intermediate states of a metal workpiece 61 shown are essentially like those in FIGS Figures 1 to 9 intermediate states shown. Identical and functionally identical elements are provided with the same reference symbols. In contrast to the recess 9, as in the Figures 1 to 9 is shown, show the Figures 10 to 18 a recess 63 with a W-shaped area 65 and a beveled area 67. The beveled area connects to the outer end of the W-shaped area 65 in each case. In this case, the beveled area 67 does not merge into another beveled area, but is directly connected to a wall inner side 69 of the metal workpiece 61 . Two inner legs of the W-shaped portion 65 are aligned at an angle of approximately 90° to one another before the metal workpiece 61 is bent. Two legs of the beveled portion 67 are oriented at an angle of about 90° to each other prior to bending the metal workpiece 61 .

the Figures 19 to 28 show further embodiments of the invention. Identical or functionally identical parts or sections are denoted by the same reference symbols.

Figure 19a shows a cross-section of a plate (10 mm thick) of a square hollow steel body as it is produced by the method according to the invention. the Figure 19b shows an enlarged section A of Figure 19a . the Figure 19c shows a representation of a circuit board based on the Figures 19a and 19b finished folded workpiece according to the present invention.

Figure 20a shows a further variant of a cross section of a plate according to the invention (here 20 mm thick) of a square hollow steel body according to the invention. At the in Figure 20a The board material shown is therefore a stronger board material. With such a 20 mm thick plate, 28.28 mm of steel would have to be welded through at an angle of 90°. However, according to the state of the art, seams welded with the help of laser beams can no longer be produced economically above a welding depth of 16 mm. The one in the Figure 20a and also in the in Figure 20b shown enlarged section A of Figure 20a illustrated further embodiment of the circuit board material according to the invention has to overcome these disadvantages advantageously according to the invention on a notch geometry compared to in Figure 19a and Figure 19b The notch geometry shown is extended by a recess, which provides for material thicknesses that can be welded through in the corners. This special notch geometry or this special board material according to the present invention was checked and recalculated using the so-called finite element method and in this way also with conventional HSS profiles (in English: Hollow Structural Section; in German: Stahlhohlprofil ) of the prior art compared. For proof, as figure 29 a corresponding study by the company IWF Ingenieurbüro Uwe Großmann from August 26, 2013 is attached.

Figure 21a shows an embodiment of a profile folded according to the invention with a plate thickness of 10 mm, which profile is butt-connected to a puzzle latch according to FIG. 21d, which latch was designed for a laser hybrid butt weld/HV. Theoretically, pure laser beam welding with an I-seam shape would be possible here; However, the invention has recognized that to fold the puzzle latch according to Figure 19b and also Figure 19c a phase is necessary. Without this phase, based on the knowledge of the invention, the side parts cannot be latched or pivoted in the last step, see also the "flower" described below. The profile edges of this embodiment according to the invention are each preferably welded through from the outside with laser beam welding.

Figure 22a shows another embodiment according to the invention of a folded profile with a blank thickness of 10 mm, which profile was laid out in the joint with a preparation for a butt joint in I-seam form. The profile edges of this embodiment are preferably each welded through with a laser beam weld from the outside.

See also the other views in the Figures 22b and 22c this embodiment.

The in the Figures 23a, 23b and 23c The illustrated embodiment of a profile according to the invention with a plate material thickness of 20 mm has been produced in a butt joint with a puzzle latch for a laser hybrid butt weld/HV (half V seam). At this point it should be noted that both the present circuit board thickness and the circuit board thicknesses described above and below are only approximate millimeter specifications in order to describe the conceptual orientation of the corresponding embodiment. The here in the Figures 23a, 23b and 23c present special advantageous notch geometry according to the invention, as in the Figures 20a, 20b and 20c can be seen, ie with an additional taper, advantageously and according to the invention ensures a weldable seam area in the corners. The profile edges are each preferably welded through from the outside with laser beam welding.

the Figures 24a, 24b and 24c show different views of an embodiment of a profile according to the invention with a plate material thickness of about 20 mm, which profile was prepared in the butt joint for a laser hybrid butt weld/HV (half V seam). The particular notch geometry according to the invention, which should again be described as preferred, as in relation to FIG Figures 20a, 20b and 20c has already been described in detail above, with an additional taper, advantageously and according to the invention ensures a weldable seam area in the corners. The profile edges of this embodiment of the invention are preferably each welded through with laser beam welding from the outside.

the Figures 25a, 25b, 25c, 25d, 25e and 25f 12 shows embodiments according to the invention of design possibilities according to the invention for the fold, which are possible using the system according to the invention described in the present patent application. while showing Figure 25a an embodiment forming an angle, Figure 25b an embodiment forming a U-steel, Figure 25c an embodiment forming a rectangular hollow profile, Figure 25d an embodiment forming a triangular hollow profile, Figure 25e an embodiment forming a square hollow profile and Figure 25f an embodiment of the present invention forming a hexagonal hollow section.

the Figures 26a, 26b, 26c, 26d, 26e and 26f show the in the Figures 25a, 25b, 25c, 25d, 25e and 25f illustrated embodiments of inventive profiles, each in a perspective view.

The representations of the embodiments according to the invention, also referred to as "flowers" above Figures 27a, 27b, 27c, 27d, 27e and 27f show, in the sequence mentioned above, an embodiment of a bending sequence according to the invention in the production of a substantially square hollow column.

the figure 28 shows in the order of the letters a to q an embodiment of a manufacturing process according to the invention based on the board used and the tools used. Step a shows the laser cutting, step b the further transport to step c, step c the edge milling, step d the joint milling, step e the joint milling, step f the joint milling, step g the joint milling, step h the further transport to step i, step i the folding/bending step j the folding/bending step k the folding/bending step I the final folding/final bending step m the laser beam welding step n the laser beam welding step o the laser beam welding step p the laser beam welding, step q the laser beam welding, wherein in step a the laser to the laser cutter is shown schematically, wherein in steps c to g the milling device is shown schematically in each case, and wherein in steps m to q the laser for laser beam welding is also shown schematically in each case.

figure 29 shows a study by the company "IWF Ingenieurbüro Uwe Großmann" from August 26, 2013, in which profiles of the prior art were compared with embodiments of the invention using the finite element method. The present invention includes the findings of pages 1 to 16 of figure 29 . In the analysis entitled "Comparative finite element analysis of two HSS-Pilar cross sections under different loads" in this analysis, a square "HSS column" according to the invention was calculated in comparison with a commercially available product. Commercially available products are, in particular, such as are shown, for example, at the in 30 illustrated page 2 of the brochure published by "Steeltube Institute of Northamerica" entitled "Hollow structural sections, column load tables" in July 1997.

Reference sign

1

metal workpiece

3, 5, 7, 9

recess

10

steel profile

11

first wall section

13

second wall section

15

third wall section

17

first connection section

19

second connection section

20

Direction

21

Feather

23

groove

30

bending edge

31

W-shaped area

33

first beveled area

34

Step

35

second beveled area

37

leg

39

leg

51

lower area

53

upper area

55

channel

61

metal workpiece

63

recess

65

W-shaped area

67

beveled area

69

wall inside

Claims (12)

1. A method for producing a steel girder, comprising the steps:

   a) providing a metal workpiece (1; 61), particularly a strip steel workpiece, which preferably has a thickness of at least 5 mm,

   b) forming a weakening in the region of a provided bend of the metal workpiece (1; 61),

   c) bending the metal workpiece (1; 61) to create a bend on the metal workpiece (1; 61),

   characterized by the step:
   d) connecting two edge regions of the bent metal workpiece (1; 61), wherein a recess (3; 5; 7; 9; 63) forming the weakening has a W-shaped region (31; 65) prior to the bending (C).
2. The method according to Claim 1,
   wherein the formation of the weakening, particularly a recess (3; 5; 7; 9; 63) forming the weakening, takes place by means of milling.
3. The method according to one of the one of the preceding claims,
   wherein a first bevelled region (33; 67) adjoins the ends of the W-shaped region (31; 65).
4. The method according to Claim 3,
   wherein the first bevelled region (33) merges into a second bevelled region (35), which preferably has a larger opening angle than the first bevelled region (33) .
5. The method according to one of the preceding claims,
   wherein the steps b) and c) are carried out twice or four times, in order to provide a triangular or rectangular girder structure.
6. A steel girder, consisting of a metal workpiece (1; 61), particularly a strip steel workpiece, which preferably has a thickness of at least 5 mm, provided with a weakening in the region of a bend of the metal workpiece (1; 61), characterized in that two edge regions of the bent metal workpiece (1; 61) are connected, wherein a recess (3; 5; 7; 9; 63) forming the weakening has a W-shaped region (31; 65) prior to the bending (C).
7. The steel girder according to Claim 6,
   wherein a first bevelled region (33; 67) adjoins the ends of the W-shaped region (31; 65) of the recess (3; 5; 7; 9; 63).
8. The steel girder according to Claim 7,
   wherein the first bevelled region (33) merges into a second bevelled region (35), which preferably has a larger opening angle than the first bevelled region (33) .
9. The steel girder according to one of Claims 6-8, comprising:

   - a first wall section,

   - a second wall section, which extends starting from a first end of the first wall section and is orientated at an angle in the range from 30° to 150° to the first wall section, and

   - a third wall section, which extends starting from a second end of the first wall section and is orientated at an angle in the range from 30° to 150° to the first wall section,

   wherein one end of the first wall section and one end of the second wall section adjoin one another for connection.
10. The steel girder according to one of Claims 6-8, comprising

    - a first (11), second (13) and third wall section (15), wherein the second (13) and third wall section (15) respectively extend starting from the first wall section (11) and are orientated at an angle of approximately 90° to the first wall section (11), and

    - a first connecting section (17), which extends starting from the second wall section (13) and is orientated at an angle of approximately 90° to the second wall section (13), and

    - a second connecting section (19), which extends starting from the third wall section (15) and is orientated at an angle of approximately 90° to the third wall section (15),

    wherein one end of the first connecting section (17) and one end of the second connecting section (19) adjoin one another for connection.
11. The steel girder according to Claim 10,

    wherein the end of the first connecting section (17) has at least one groove (23) and

    wherein the end of the second connecting section (19) has at least one tongue (21), which is constructed to correspond to the groove (23).
12. The steel girder according to Claim 10 or 11,
    wherein the ends of the first (17) and second connecting section (19) are connected to one another by means of at least one dovetail joint.

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