Method for manufacturing a screw foundation for fastening elements in the ground - Patents.com

Abstract

The present invention relates to a method for manufacturing a screw base (12) for fastening an element in the ground, in which a cylindrical tube (1) is provided as an initial form, and then a tapered front part (10) tapering towards a lead-in tip (9) is formed on the cylindrical tube (1) without cutting, and the front part (10) is at least locally provided with a thread-like profile (11) for screwing into the ground. It is envisaged that an internal profile (2) for a screwing tool is formed at the rear end (1a) of the tube (1) by flow forming, and that the front part (10) and the thread-like profile (11) are formed exclusively by flow forming.

Description

[Technical field]

[0001] The invention relates to a method for producing a screw base for fastening an element in the ground, in which a cylindrical tube is provided as an initial form, on which a tapered front part, tapering towards a leading tip, is then formed without cutting, and which front part is at least locally given a thread-like profile for screwing into the ground. [Background technology]

[0002] The screw foundation may be formed at the rear end for inserting a pile or rod, or may be provided with a flange-like fixed attachment at the rear end to which other elements, such as a frame, can be screwed.

[0003] Such a method is known from DE 19836370. This method for producing fastening devices for rods, poles, masts etc. in the ground, in particular ground anchors, having a base body, at least a subsection of which is provided with a screw-like or screw-like external thread for screwing into the ground and unscrewing it again from the ground, and which base body has a cone-shaped basic shape with at least a substantially cone-shaped subsection, is characterized in that the base body, which consists essentially of a cylindrical tube, is hammered into the basic shape.

[0004] This method certainly offers advantages in production over metal casting methods, but it is still relatively expensive, since only the basic shape is produced from the tube by forming, i.e. hammering. However, it is subsequently necessary to weld the male thread to the base body as a formed part, and possibly to attach the fin-shaped surface element to the base body, preferably also by welding. Therefore, this method is also expensive. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] West German Patent No. 19836370 Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE DISCLOSURE The object of the present invention is to substantially simplify the production of a screw foundation for fastening elements in the ground. [Means for solving the problem]

[0007] This problem is solved according to the invention in a method of the type mentioned at the beginning in that at the rear end of the tube an internal contour for a screw-in tool is produced by flow forming and that the front and threaded contours are produced exclusively by flow forming.

[0008] The thread base is therefore produced exclusively by flow forming, which significantly reduces production costs and allows accurate and reproducible parts to be produced. In this case, the internal profile can be produced first, followed by the front and thread-like profile, or vice versa. As the initial form, a drawn or electric resistance welded tube can be used.

[0009] In a particularly preferred embodiment, it is provided that the tube is first ironed at least regionally, which allows the material properties on the one hand and the geometric dimensions on the other hand to be changed.

[0010] According to a first embodiment, it is contemplated that the front portion is formed first and then the threaded profile is formed.

[0011] In this case, it may be provided that the threaded profile is also regionally formed in the area adjacent to the front part of the tube.

[0012] Alternatively, it may be envisaged that the front and threaded profiles are formed simultaneously.

[0013] In this case, the thread profile may be formed with different flank geometries and / or different pitches in different regions.

[0014] In another aspect, it is contemplated that during flow forming, the tube is at least temporarily positioned over an internal mandrel, which may be used, for example, to form an internal contour.

[0015] In this case, it may be contemplated that a multi-piece inner mandrel may be used.

[0016] Furthermore, it is expedient if a tailstock is introduced at least temporarily in the front during flow forming.

[0017] The tailstock may be spring loaded or mechanically controlled.

[0018] If a completely closed lead-in tip is to be achieved, it is contemplated that the front end of the lead-in tip is closed by molding after flow forming.

[0019] The invention is explained in more detail exemplarily below with reference to the drawings. [Brief description of the drawings]

[0020] [Figure 1] A longitudinal section through the initial cylindrical tube [Diagram 2] Longitudinal section through a tube during ironing of the internal contour [Diagram 3] Longitudinal cross section through a tube during ironing [Figure 4] Longitudinal section through a tube being ironed to produce a threaded profile [Diagram 5] Longitudinal cross section through a tube after flow forming [Figure 6] Perspective view of the completed screw foundation DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] First, note that the scale of the individual figures does not match.

[0022] For the method for producing a screw foundation for fastening an element in the ground, firstly a cylindrical tube 1 is provided as an initial form. This tube 1 can be a drawn or electric resistance welded tube made of metal.

[0023] In the illustrated process sequence, the tube 1 is clamped in a flow forming machine, not shown in detail, and firstly the inner contour 2, for example in the form of a spline, is formed by flow forming at the rear end 1a. For this purpose, an inner mandrel 3 is inserted at the rear end 1a of the tube 1, which has on its outside an outer contour 4 complementary to the inner contour 2. This outer contour 4 is formed in the central region 3a of the inner mandrel 3, while towards the axial left or outside, the inner mandrel 3 has an outer region, not shown, which does not have an outer contour, for clamping together with the rear end 1a of the tube 1 in the chuck 13. To the axial right or inside, the inner mandrel 3 has an inner region, which has a smaller diameter than the central region 3a, in order to be able to reduce the outer diameter of the tube 1 adjacent to the inner contour 2 to be formed.

[0024] After the inner mandrel 3 has been inserted into the rear end 1a of the tube 1, for example two circumferentially symmetrically arranged spinning rollers 5 are fed radially to the rear end 1a of the tube 1 and moved axially along the inner mandrel 3. This results in an inner contour 2 being formed in the tube 1 and a step 6 of reduced diameter being formed in the tube 1 axially adjacent to this inner contour. In this case, the spinning rollers 5 are of course brought into a rotational movement relative to the tube 1, i.e. either the tube 1 is rotated or a driven spinning roller 5 is used.

[0025] If desired for geometric reasons (tube elongation) and / or strength reasons, the tube 1 is axially ironed by feeding the spinning roller 5 radially relative to the tube 1 and moving axially towards the right. To this end, the inner mandrel 3 can be replaced by an inner mandrel 3' which differs from the inner mandrel 3 only by having a longer inner region 3b'. Ironing can also be carried out selectively without an inner mandrel.

[0026] In FIG. 2, the ironed area of ​​the tube 1 adjacent to the step 6 has already been illustrated and is designated 1b, but FIG. 2 still shows the inner mandrel 3 in the engaged state. In reality, however, the ironing only takes place after the removal of the inner mandrel 3 and the insertion of the inner mandrel 3' (FIG. 3). In this case, a tailstock 7 can already be introduced into the open front end 1c of the tube 1. This tailstock 7 can be spring-loaded or mechanically controlled. The tailstock 7 serves as a support for the front end 1c of the tube 1 for forming the tapered area 8 by the radial feed of the spinning roller 5 (FIG. 3).

[0027] This tapered region 8 is shaped by the spinning roller 5 into a tapered front portion 10 which tapers further forward towards a still open leading tip 9, so that the spinning roller 5 is increasingly pressed radially against the tube 1 in the direction of the leading tip 9.

[0028] Thereafter, or at least temporarily simultaneously with the tapered deformation of the front portion 10, a thread-like profile 11 is formed by the spinning roller 5' in the front portion 10, and preferably not only in the front portion 10 but also in the adjacent cylindrical ironed region 1b of the tube 1 (Figures 4 and 5).

[0029] In Fig. 5 the flow forming process has been completed and the tailstock 7 has been withdrawn from the tube 1. To finally produce the screw base 12 for fastening the element in the ground, it is only necessary to close off the front end of the lead-in tip 9. This is done by suitable shaping, for example compressing, punching or folding and possibly subsequent trimming.

[0030] The final screw foundation 12 is shown in FIG.

[0031] Naturally, the invention is not limited to the embodiment shown. Other configurations are possible without departing from the basic idea. It is therefore not necessary for the internal contour 2 to be formed first. This process step can also be carried out at a later point in time. The formation of the thread-like contour 11 can also take place at least temporarily simultaneously with the shaping of the front part 10. The internal contour 2 can also be (pre-)formed, at least in part, by compression of the chuck 13 during the insertion of the internal mandrel 3. In addition, the present application relates to the invention described in the claims, but may also include the following as other aspects. 1. A method for manufacturing a screw base (12) for fastening an element in the ground, in which a cylindrical tube (1) is provided as an initial form, on which a tapered front part (10) is then formed without cutting, tapering towards a leading tip (9), and the front part (10) is at least locally provided with a threaded profile (11) for screwing into the ground, The method is characterized in that at the rear end (1a) of the tube (1) an internal contour (2) for a screwing tool is formed by flow forming, and the front part (10) and the threaded contour (11) are formed exclusively by flow forming. 2. 2. The method according to claim 1, characterized in that the tube (1) is first ironed at least regionally. 3. 3. The method according to claim 1 or 2, characterized in that first the front part (10) is formed and then the threaded profile (11) is formed. 4. 4. The method according to claim 3, characterized in that the thread-like profile (11) is also formed regionally in the region (1b) adjacent to the front part (10) of the tube (1). 5. 3. The method according to claim 1 or 2, characterized in that the front portion (10) and the threaded profile (11) are formed simultaneously. 6. 6. The method according to any one or more of 1 to 5 above, characterized in that during flow forming the tube (1) is at least temporarily placed on an internal mandrel (3, 3'). 7. 7. The method according to claim 6, wherein a multi-piece inner mandrel is used. 8. 8. The method according to any one or more of claims 1 to 7, characterized in that during flow forming, a tailstock (7) is introduced at least temporarily in the front part (10). 9. 9. The method according to claim 8, characterized in that a spring-loaded or mechanically controlled tailstock (7) is used. 10. 10. The method according to any one or more of the above 1 to 9, characterized in that the front end (9a) of the introduction tip (9) is closed by molding after flow forming. [Explanation of symbols]

[0032] 1. Cylindrical tube 1a rear end 1b Ironed area 1c front end 2. Internal Contours 3,3' Inner Mandrel 3a,3a' central area 3b,3b' inner area 4 External Contour 5 Spinning roller 6 steps 7 Tailstock 8 Tapered Area 9 Introduction tip 9a front end 10 front 11 Threaded contour 12 Screw foundation 13. Chuck

Claims

1. 1. A method for manufacturing a screw base (12) for fastening an element in the ground, in which a cylindrical tube (1) is provided as an initial form, on which a tapered front part (10) is then formed without cutting, tapering towards a leading tip (9), the front part (10) being at least locally provided with a threaded profile (11) for screwing into the ground, 1. A method according to claim 1, characterized in that at the rear end (1a) of a tube (1) an internal profile (2) for a screwing tool is formed by flow forming, and that the front part (10) and the thread-like profile (11) are formed exclusively by flow forming, and that the flow forming is carried out by axially moving two spinning rollers (5, 5') arranged symmetrically around the tube (1) or arranged asymmetrically and axially spaced around the tube (1) while feeding them radially relative to the rotating tube (1), using the spinning rollers (5') arranged asymmetrically and axially spaced around the tube (1) to form the thread-like profile (11).

2. 2. The method according to claim 1, characterized in that the tube (1) is first ironed at least regionally.

3. 3. A method according to claim 1 or 2, characterized in that first the front part (10) is formed and then the thread-like profile (11) is formed.

4. 4. A method according to claim 3, characterised in that the thread-like profile (11) is also regionally formed in the region (1b) adjacent to the front part (10) of the tube (1).

5. 3. A method according to claim 1 or 2, characterized in that the front portion (10) and the threaded profile (11) are formed simultaneously.

6. Method according to any one of the preceding claims, characterised in that during flow forming the tube (1) is at least temporarily placed on an internal mandrel (3, 3').

7. 7. The method according to claim 1, characterized in that during flow forming, a tailstock (7) is introduced at least temporarily into the front part (10).

8. 8. Method according to claim 7, characterized in that a spring-loaded or mechanically controlled tailstock (7) is used.

9. 9. The method according to any one of the preceding claims, characterized in that the front end (9a) of the inlet tip (9) is closed by molding after flow forming.

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