METHOD FOR PRODUCING A SCREW FOUNDATION

Description

[0001] The invention relates to a method for producing a screw foundation for fastening elements in a substrate, in which at least one first cylindrical tube is provided as a first starting form and the first tube is provided at least partially adjacent to a front insertion end with a thread-like outer contour for screwing into the substrate, wherein a star-shaped contour having internal and external teeth is formed into a rear end of the first tube by forming.

[0002] Screw foundations are available in various designs. They can be designed at the rear end for inserting piles or rods, or alternatively, they can have a plate- or flange-like fastening element at the rear end to which other elements, e.g., frames or the like, can be attached.

[0003] A method with the features of the preamble of claim 1 is known from the unpublished document DE 10 2021 130 720 B3. An arrangement for connecting two nested tubes is known from US 2017 / 0 058 940 A1. Another method for manufacturing screw foundations is known from DE 10 2010 010 603 A1.

[0004] From DE 10 2019 128 030 B3, a method for manufacturing a screw foundation for securing elements in the ground is known, in which a cylindrical tube is provided as the starting form, to which a conical front section tapering to an insertion tip is formed without machining. The front section is provided, at least in part, with a threaded outer contour for screwing into the ground. A key feature of this method is that an inner contour for a screwing tool is formed into a rear end of the tube by die rolling, and that the front section and the threaded outer contour are formed exclusively by die rolling. The screw foundation is thus manufactured solely by die rolling, which reduces manufacturing effort and enables the production of precise and reproducible components.Either the inner contour can be formed first, followed by the front section and the threaded outer contour, or vice versa. A drawn or welded tube can be used as the starting material.

[0005] In practice, it has been found that with a screw foundation produced in this way, the torque that can be transferred from the screwing tool to the inner contour of the screw foundation is limited, so that the screw foundation is less suitable for certain soil conditions or for particularly large penetration depths.

[0006] The object of the invention is to create a screw foundation that is easy to manufacture and suitable for any soil conditions and preferably any penetration depth.

[0007] This problem is solved according to the invention in a method of the type described above by forming a star-shaped pre-contour radially from the outside against a star-shaped counter-form arranged inside the tubular end in a first step, and in a second step forming the star-shaped pre-contour radially from the outside to the star-shaped contour without an internal counter-form.

[0008] The contour at the rear end of the screw foundation is thus formed externally in two stages without the use of chips, creating both internal and external serrations. The external and internal serrations serve for a rotationally fixed connection with a screw-in tool having a complementary serration contour. The internal serration is suitable for the rotationally fixed mounting of a tubular extension element, resulting in a screw foundation consisting of at least two parts. Furthermore, the internal serration is suitable for mounting a plate- or flange-like fastening element, the fastening element being equipped with a contour corresponding to the star-shaped contour. The star-shaped contour allows for the transmission of high torques, enabling screwing into substrates with various soil conditions. The star-shaped contour can be designed similarly to a screw drive profile with the standard designation "internal Torx" or similar."External hexagon", but the number of teeth is arbitrary.

[0009] It is preferably provided that the star-shaped pre-contour and the star-shaped contour at the rear end of the first tube are formed by several forming tools arranged on a common circumference and adjustable radially at a uniform rate. The forming tools can be, for example, pressing or stamping tools.

[0010] It is advantageously provided that the star-shaped contour is formed conically in the axial longitudinal direction of the first tube, starting from the rear end. The inner cross-section of the star-shaped contour thus decreases longitudinally from the rear end. The forming tools are accordingly complementary in shape.

[0011] It can be provided that the rear tubular end is radially expanded before the star-shaped pre-contour is formed. For this purpose, the tubular end is held axially during forming, for example, by several clamping jaws. A guided expanding mandrel is inserted into the tube and thus expands the tube end. This forming process can also be carried out in multiple stages, i.e., with several expanding mandrels that are successively larger. Alternatively, it can also be provided that the tubular end is drawn in, i.e., its diameter is reduced. For this purpose, for example, a guided drawing-in ring is pushed axially over the tube and thus reduces the diameter of the tube end.

[0012] In most applications, a tapered front section, leading to an insertion tip, is formed onto the first pipe without machining. This front section is at least partially provided with a threaded outer contour for screwing into the subsoil. During screwing, the longer or shorter threaded outer contour displaces and compacts the subsoil material outwards, thus improving the anchoring of the screw foundation in the ground.

[0013] To simplify manufacturing, it is particularly preferred that the front section is produced by compression molding with or without heat. The outer contour is then formed by roller forming. Compression molding can also be carried out in multiple stages.

[0014] In a particularly preferred embodiment, it is provided that at least a second cylindrical tube is provided as a second initial shape and that a star-shaped contour having internal and external teeth is formed into each of the two tubular ends of the second tube, wherein in a first step a star-shaped pre-contour is formed radially from the outside against a star-shaped counter-contour arranged inside the tubular end and in a second step the star-shaped pre-contour is formed radially from the outside to the star-shaped contour without an internal counter-contour, wherein the contour at one end of the second tube corresponds to the contour at the rear end of the first tube and the contour at the other end of the second tube is designed such that the other end of the second tube can be inserted into or onto the rear end of the first tube in a force-fit and / or form-fit manner.The screw foundation advantageously consists of at least two parts: the element made from the first tube and at least one extension element that can be inserted into the rear of the aforementioned element in a rotationally fixed manner. The second tube is also preferably provided, at least partially, with a threaded outer contour for screwing into the subsoil, e.g., by pressure rolling. However, the threaded outer contour can also be omitted. To ensure that the threads of the threaded outer contours of the first and the at least one second tube do not misalign when inserted into one another, a positioning aid is preferably molded into the star-shaped contours.

[0015] It can be advantageously provided that the nested ends of the first and second pipes are secured to each other in the area of ​​the star-shaped contours by at least one screw extending transversely to the longitudinal axis of the first and second pipes. This can be done during assembly, for example, when the first pipe is already largely screwed into the substrate and only its rear end protrudes. The second pipe can then be attached and subsequently secured with the transverse screw. Clinching is also possible.

[0016] The invention is explained in more detail below with reference to the drawing. This shows in Fig. 1 a perspective view of a screw foundation, Fig. 2 an enlarged view of the rear end of the screw foundation according to Fig. 1Fig. 3 a cross-section of a cylindrical tube as the first initial form, Fig. 4 a cross-section through the rear tube end of the screw foundation during a first forming step, Fig. 5 a cross-section through the rear tube end of the screw foundation during a second forming step, Fig. 6 a cross-section through the rear tube end of the screw foundation after forming, Fig. 7 a perspective view of a tubular extension element for forming a two-part screw foundation, Fig. 8 a perspective view of the front end of the extension element after forming Fig. 7 Fig. 9 a perspective exploded view of a two-part screw foundation before assembly, Fig. 10 an enlarged detail of the Fig. 9Fig. 11 shows a perspective view of the connection area of ​​the two-part screw foundation after assembly, Fig. 12 shows a longitudinal section through a pipe end during expansion, Fig. 13 shows a longitudinal section through a pipe end during compression, Fig. 14 shows a longitudinal section through a pipe end during compression molding to form a tapered front section, Fig. 15 shows a longitudinal section through a screw foundation after the formation of an outer contour, and Fig. 16 shows a longitudinal section through the completed screw foundation.

[0017] A one-piece screw foundation is in Fig. 1 generally designated by 1. This screw foundation 1 exhibits the following characteristics in the exemplary embodiment: Fig. 1The screw foundation 1 has a rear end 1a and a front insertion end 1b. A star-shaped contour 2, described in more detail below, is formed into the rear, tubular end 1a. Axially adjacent to this star-shaped contour 2, the screw foundation 1 has a cylindrical section 1c and, adjoining this, a front section 1d that tapers conically to an insertion tip 3 at the front insertion end 1b.

[0018] Both the front section 1d and the cylindrical area 1c are provided, at least partially, with a thread-like outer contour 4, which is preferably formed exclusively by pressure rolling. For a more detailed explanation, reference is made to publication DE 10 2019 128 030 B3.

[0019] To produce the screw foundation 1 described above, a first cylindrical pipe 5 is provided as the initial starting form. This pipe 5 can be a drawn or welded metal pipe.

[0020] The star-shaped contour 2 is formed into one end of the tube 5, which forms the rear end 1a of the screw foundation 1, in such a way that it has an internal toothing 2a and an external toothing 2b. For this purpose, the rear end of the first tube 5 is inserted into a suitable forming device, which has several forming tools 6 arranged on a common circumference and which can be adjusted radially in a uniform manner ( Fig. 4 In a first step, a star-shaped pre-contour 2' is formed radially from the outside against a star-shaped counter-form 6a arranged inside the tubular end by means of the radially inwardly moving forming tools 6 ( Fig. 4 ). Subsequently, the counter-form 6a is removed and in a second step the star-shaped pre-contour 2' is formed radially from the outside to the star-shaped contour 2 without the inner counter-form 6a, by again moving the forming tools 6 radially inwards ( Fig. 5 ).

[0021] The forming tools 6 are each moved radially inwards at a uniform rate towards the end of the first tube 5, so that the star-shaped contour 2, which has an internal toothing 2a and an external toothing 2b, is formed ( Fig. 6 The wall thickness of the first pipe 5 does not change significantly.

[0022] After forming the star-shaped contour 2, the first tube 5 is preferably inserted with its rear end, featuring the star-shaped contour 2, into a complementarily designed clamping and holding tool of a flow forming machine. Subsequently, the first tube 5 is preferably flow forming into the Fig. 1The depicted shape of the finished screw foundation 1 is formed, with reference to German patent DE 10 2019 128 030 B3 for the execution of the flow forming processes. The tube 5 can optionally be stretched first, but this step can also be omitted. After the flow forming process is complete, the insertion tip 3 is closed in a suitable manner. Alternatively, the thread-like outer contour 4 can be formed first, followed by the star-shaped contour 2.

[0023] The star-shaped contour 2 at the rear end 1a of the screw foundation 1 has a dual function. The external toothing 2b serves for connection with a correspondingly complementary screw-in tool (not shown). The internal toothing 2a, on the other hand, serves for the force-fit and / or form-fit reception of a tubular extension element 7 to form a two-part screw foundation 1.

[0024] To produce the tubular extension element 7, a second cylindrical tube is provided as a second starting form. Both the front end 7a and the rear end 7b of the extension element 7 are machined in the same way as in the Figs. 4 to 6 A star-shaped contour 8, 9 is shown, each with an internal toothing 8a, 9a and an external toothing 8b, 9b formed by two-stage radial pressing from the outside with and without an internal counter-form.

[0025] The contour 8 at the front end 7a of the extension element 7 is dimensioned such that the front end 7a can be inserted into the rear end 1a of the screw foundation 1 in a force-fit and / or form-fit manner. In contrast, the star-shaped contour 9 at the rear end 7b corresponds to the star-shaped contour 2 of the screw foundation 1, so that the rear end 7b of the extension element 7 is suitable either to be coupled to the screwing tool or to accommodate another extension element 7.

[0026] The cylindrical area 7c between the two ends 7a and 7b of the extension element 7 is preferably also provided with a thread-like outer contour 10 by means of pressure rollers.

[0027] If a two- or multi-part screw foundation 1 is to be used, which consists of the screw foundation 1 according to Fig. 1and consists of at least one extension element 7, the front end 7a of the extension element 7 is attached at the deployment site according to the sequence of Figs. 9 to 11 inserted into the rear end 1a of the screw foundation 1 in a form-fitting and / or force-fitting manner.

[0028] To achieve a secure connection, the nested ends 1a, 7a can be secured to each other in the area of ​​the star-shaped contours 2, 8 by at least one screw connection extending transversely to the longitudinal axis of the first and second tubes. Alternatively, a clink connection is also possible.

[0029] A plate- or flange-like mounting element (not shown) can also be inserted into the rear end 1a or 7b and, if necessary, locked in place. This mounting element is equipped with a contour corresponding to the star-shaped contour 8. The mounting element with the star-shaped contour can be manufactured, for example, by deep drawing. Other elements, such as frames or the like, can be attached to such a mounting element.

[0030] The first tube 5 for the screw foundation 1 or the second tube for the tubular extension element 7 can be reshaped, namely widened or drawn in, at the relevant end before the formation of the star-shaped contour 2, 8, 9.

[0031] In Fig. 12 Figure 1 shows how the rear tubular end 1a of the first tube 5 is radially widened before the formation of the star-shaped pre-contour 2'.

[0032] For this purpose, the rear tubular end 1a is held axially during the forming process, for example by several clamping jaws (not shown). A guided expanding mandrel 11, which has a larger outer diameter than the inner diameter of the tube 5, is pushed axially into the tube 5 and thus expands the tube end.

[0033] Alternatively, according to Fig. 13 It is also provided that the tubular end 1a is drawn in, i.e., its diameter is reduced. For this purpose, for example, a guided drawing-in ring 12 is pushed axially over the tube 5 and thus reduces the tube end.

[0034] Depending on requirements, the widening or narrowing can also be carried out on one or both sides of the tubular extension element 7 in the same way.

[0035] The tapered front section 1d of the screw foundation 1 can be produced by compression molding. For this purpose, according to Fig. 14A forming tool 13 with a conically tapered inner recess 14 is moved in an axial direction in one or more stages against the front insertion end 1b.

[0036] Subsequently, the thread-like outer contour 4 is formed by pressure rolling, and the conically tapered front section 1d is further formed ( Fig. 15 ).

[0037] In Fig. 16 The finished screw foundation 1 is shown, with the tip 3 also closed, e.g. by compression and possibly welding. Reference symbol list:

[0038] 1 Screw foundation 1a Rear end 1b Front insertion 1c Cylindrical section 1d Conical front section 2 Star-shaped contour 2a Star-shaped pre-contour 2a Internal toothing 2b External toothing 3 Insertion tip 4 Threaded external contour 5 First cylindrical tube 6 Forming tool 6 Star-shaped counter-mold 7 Tubular extension element 7a Front end 7b Rear end 7c Cylindrical section 8 Star-shaped contour 8a Internal toothing 8b External toothing 9 Star-shaped contour 9a Internal toothing 9b External toothing 10 Threaded external contour 11 Expanding mandrel 12 Draw-in ring 13 Forming tool 14 Internal recess

Claims

1. Method for producing a screw foundation (1) for fastening elements in a foundation soil, in which at least a first cylindrical tube (5) is provided as a first starting form and the first tube (5) adjacent to a front insertion end (1b) is provided at least in some areas with a thread-like outer contour (4) for screwing into the foundation soil, wherein a star-shaped contour (2) with internal toothing and external toothing (2a, 2b) is shaped-in by reshaping into a rear end (1a) of the first tube (5), wherein, in a first step, a star-shaped pre-contour (2') is shaped-in radially from the outside against a star-shaped counter-form (6a) arranged inside the tubular end (1a) and, in a second step, the star-shaped pre-contour (2') is shaped-out radially from the outside to the star-shaped contour (2) without an inner counter-form.

2. Method according to claim 1, characterized in that the star-shaped pre-contour (2') and the star-shaped contour (2) at the rear end (1a) of the first tube (5) are shaped-in by a plurality of reshaping tools (6) arranged on a common circumference and uniformly radially adjustable.

3. Method according to claim 1 or 2, characterized in that the star-shaped contour (2) is formed conically tapering from the rear end (1a) in the axial longitudinal direction of the first tube (5).

4. Method according to one or more of claims 1 to 3, characterized in that the rear tubular end (1a) is radially expanded before the star-shaped pre-contour (2') is shaped-in.

5. Method according to one or more of claims 1 to 4, characterized in that a conical front section (1d) tapering to an insertion tip (3) is shaped onto the first tube (5) using a non-cutting process, wherein the front section (1d) is formed at least in some areas with the thread-like outer contour (4) for screwing into the foundation soil.

6. Method according to claim 5, characterized in that the front section (1d) is produced by compression molding with or without heat application.

7. Method according to one or more of claims 1 to 6, characterized in that at least a second cylindrical tube is provided as a second starting form and that a star-shaped contour (8, 9) with internal toothing and external toothing (8a, 8b, 9a, 9b) is shaped-in into each of the two tubular ends (7a, 7b) of the second tube, wherein, in a first step, respectively a star-shaped pre-contour is shaped-in radially from the outside against a star-shaped counter-form arranged inside the tubular end, and, in a second step, respectively the star-shaped pre-contour is shaped-out radially from the outside to the star-shaped contour without an inner counter-form, wherein the contour (9) at one end (7b) of the second tube corresponds to the contour (2) at the rear end (1a) of the first tube, and the contour (8) at the other end (7a) of the second tube is designed such that the other end (7a) of the second tube can be inserted into or onto the rear end (1a) of the first tube in a force-fitting and / or form-fitting manner.

8. Method according to claim 7, characterized in that the sticked into each other ends (1a, 7a) of the first and second tubes are secured to each other in the area of the star-shaped contours (2, 8) by at least one screw connection extending transversely to the longitudinal axis of the first and second tubes.