FASTENING ELEMENT AND METHOD

Abstract

The invention relates to a fastening element, comprising an insertion segment for inserting into a bore, having a self-tapping threaded segment having an external thread for screwing and tapping into the bore on a fastening object, and comprising a mounting segment for arranging outside of the bore, having an interface geometry for applying a torque to the fastening wherein it should be possible to fix a fixing part to the fastening element in a simple manner. This aim is achieved in that the mounting segment is additionally provided with a fixing device for indirectly or directly, in particular interlockingly and/or frictionally, fixing a fixing part on the mounting

Claims

1. A fastening element comprising an insertion section for insertion along a longitudinal axis into a bore on an object for fastening, the fastening element having a self-tapping threaded section with a thread lead-in for tapping an internal thread into the bore and an external thread connected to the thread lead-in along the longitudinal axis for screwing the fastening element into the bore, wherein the external thread has a constant external diameter (dga), a constant core diameter (dgk) and a constant thread pitch (p) along the longitudinal axis, wherein the thread lead-in has a usable region and an increasing external diameter along the longitudinal axis, a mounting section for arrangement outside of the bore, the mounting section having an interface geometry for applying a torque to the fastening element, wherein the usable region of the thread lead-in has a length along the longitudinal axis that is at most 1.3 times the constant thread pitch (p) of the external thread.

2. The fastening element according to claim 1, the length of the usable region of the thread lead-in along the longitudinal axis is at most 1.2 times the constant thread pitch (p) of the external thread.

3. The fastening element according to claim 1, wherein the length of the usable region of the thread lead-in along the longitudinal axis is at least 0.4 the constant thread pitch (p) of the external thread.

4. The fastening element according to claim 1, wherein the external thread has a thread height (h) of between 0.2 mm and 1.5 mm.

5. The fastening element according to claim 1, the constant thread pitch (p) is between 0.5 mm and 2 mm.

6. The fastening element according to claim 1, wherein of the external thread has a flank angle of between 45 and 75.

7. The fastening element according to claim 1, the threaded section has a constant external diameter (dga) between 2 mm and 20 mm and/or the threaded section has an axial extent as a thread length (gl) in the direction of a longitudinal axis of the fastening element between 3 mm and 10 mm.

8. The fastening element according to claim 1, wherein the thread lead-in has a hardness of material of at least 800 MPa.

9. The fastening element according to claim 1, wherein the external thread is made of a hardened steel.

10. The fastening element according to claim 1, further comprising a fixation device comprising an add-on external thread, or an internal thread or a clip element or a catch element.

11. A method for manufacturing a fastening element comprising: a) making available a semifinished product having a longitudinal axis, b) mounting an interface geometry on the semifinished product, for applying a torque to the fastening element, c) applying a thread to create a self-tapping thread in the semifinished product, wherein the self-tapping thread extends along the longitudinal axis up to one end face of the semifinished product, d) creating a bevel on the end face of the semifinished product separately from c), wherein the bevel is created for forming a thread lead-in for tapping an internal thread into a bore wherein the self-tapping thread and the bevel and an external thread connected to the thread lead-in along the longitudinal axis for tapping a thread into the bore overlap at least partially along the longitudinal axis.

12. The method according to claim 11, d) is carried out after c).

13. The method according to claim 11, c) is carried out after d).

14. A method for fastening the fastening element according to claim 1, onto an object for fastening comprising: creating a bore into the object for fastening, screwing the fastening element into the bore, so that an internal thread is cut from the external thread on the fastening element into the object for fastening at the bore and the fastening element is fastened onto the object for fastening, the method including meshing the internal thread of the object for fastening with the external thread of the fastening element with a radial furrow (d) between 0.2 mm and 2 mm.

15. The method according to claim 14, including forming the bore as a blind hole with a bore length (bl) between 3 mm and 12 mm, and/or screwing the external thread of the fastening element with a thread immersion length (gel) between 2 mm and 8 mm into the object for fastening.

16. The fastening element of claim 1, wherein the increasing external diameter along the longitudinal axis of the thread lead-in is larger than the useable region of thread lead-in than a core diameter (dgk) of the external thread.

17. The fastening element of claim 2, wherein the length of the usable region of the thread lead-in along the longitudinal axis is a most 1.15 times the constant thread pitch (p) of the external thread.

18. The fastening element of claim 3, wherein the length of the usable region of the thread lead-in along the longitudinal axis is at least 0.5 times the constant thread pitch (p) of the external thread.

19. The fastening element of claim 4, wherein the thread height (h) of the external thread is between 0.4 mm and 1.0 mm.

20. The fastening element of claim 5, wherein the constant thread pitch (p) is between 0.6 mm and 1.3 mm.

Description

[0036] Exemplary embodiments of the invention are described in greater detail below with reference to the accompanying drawings, in which:

[0037] FIG. 1 shows a longitudinal section through a fastening element in a first exemplary embodiment,

[0038] FIG. 2 shows a longitudinal section through the fastening element in a second exemplary embodiment,

[0039] FIG. 3 shows a longitudinal section through the fastening element according to FIG. 1 in a bore in an object for fastening,

[0040] FIG. 4 shows a partial longitudinal section through an external thread of the fastening element in FIG. 3, which is screwed into the object for fastening,

[0041] FIG. 5 shows a side view of a fastening element in a third exemplary embodiment, and

[0042] FIG. 6 shows a partial view of the fastening element according to FIG. 5.

[0043] FIG. 1 illustrates a first exemplary embodiment of a fastening element 1 made of steel in a longitudinal section. The one-piece fastening element 1 has an insertion section 2 and a mounting section 5. The insertion section 2 is used to insert the fastening element into a bore 19 on an object for fastening 18 (FIG. 3). The bore 19 is embodied as a blind hole 21. The insertion section 2 is subdivided into a threaded section 3 and a threadless transitional section 4, wherein the threaded section 3 comprises an external thread 8 and a thread lead-in 22. The transitional section 4 has an increasing diameter because it serves as the transition to the mounting section 5, and the mounting section 5 has a larger external diameter daa than the threaded section 3 with its external diameter dga. The threaded section 3 with the external diameter 8 on the insertion section 2 also has a core diameter dgk.

[0044] An add-on external thread 10 is formed on the mounting section 5 on the outside as a fixation device 9. The add-on external thread 10 as a fixation device 9 serves the purpose of direct and indirect fastening of a fixation part. The fixation part is a grating or a line or a rail, for example, and should be fastened to the fastening element 1. To do so, the fixation element may either be screwed directly onto the external thread 10 or an intermediate part is screwed onto the external thread 10 and then the fastening part is fastened to the intermediate part (not shown). The fastening part may also be placed over the external thread with a bore or the like and tightened securely with a nut as the intermediate part.

[0045] The fastening element 1 has a front end face 6 and a rear end face 7. A bevel 17 having a bevel angle of 31, for example, is formed on the threaded section 3 on the front end face 6 and/or on the front end area of the fastening element 1, i.e., the threaded section 3. For insertion of the fastening element 1 into the bore 19, the fastening element 1 can therefore be inserted more easily into the bore 19 because of the bevel 17. Furthermore, an interface geometry 12 for applying a torque to the fastening element 1 is formed on a rear end region of the fastening element 1. To this end, a recess 15 is cut on the mounting section 5 on the rear end face 7 and an internal hexagon 13 is formed on the recess 15. Therefore after insertion of a front end region of the fastening element 1 into the bore 19, a tool, for example, a hexagon insert bit wrench may be inserted into the internal hexagon 13 and a torque applied to the fastening element 1 and a compressive force applied forward to the fastening element 1 in the direction of the longitudinal axis 11, so that, in this way, an internal thread into the bore 19 of the blind hole 21 can be cut in a self-tapping manner on the object for fastening 18 by means of the thread lead-in 22 on the threaded section 3.

[0046] The thread lead-in 22 has an external diameter that increases steadily along the longitudinal axis 11. A usable range 23 of the thread lead-in 22 has an external diameter greater than the core diameter dgi of the external thread 8 because a region of the thread lead-in with a smaller external diameter, which may optionally be present, cannot be utilized for forming the thread. The length of the usable region 23 of the thread lead-in 22 along the longitudinal axis 11 is essentially half as large as the thread pitch p of the external thread 8.

[0047] FIG. 2 shows a second exemplary embodiment of the rod-shaped and bolt-shaped fastening element 1. In the following discussion, essentially only the differences in comparison with the first embodiment according to FIG. 1 will be described. The interface geometry 12 is embodied as a hexagon insert bit 14, as a protrusion 16 on the rear end region of the fastening element 1. To this end, the protrusion 16 is formed on the mounting section 5.

[0048] FIG. 3 shows the first exemplary embodiment of the fastening element 1 illustrated in FIG. 1, which is fastened in the bore 19. For fastening the fastening element 1 on the fastening element 18, i.e., a wall 20 of a vessel with a thickness of 4 mm to 8 mm, first the blind hole 21 is cut as a bore 19 with a bore length bl of 3 mm using a drill. Therefore, there remains a residual thickness of the wall 20 of 2 mm, for example, at the end of the blind hole 21. Next the insertion section 2 of the fastening element 1 is inserted into the bore 19 until the bevel 17 comes to rest on the blind hole 21 and/or the border of the blind hole 21 formed by the object for fastening 18 because the external diameter dga of the threaded section 3 is identical to the external diameter of the bevel 17. The external diameter dga of the threaded section 3 is greater than the diameter of the bore 19. Next, a torque is applied to the fastening element 1 by means of the internal hexagon socket, and a compressive force is applied in the direction of the longitudinal axis 11 in a self-tapping manner from the thread lead-in 22 and/or its usable region 23 on the threaded section 3 into the bore 19.

[0049] After screwing the fastening element 1 completely into the bore 19, there is a thread immersion length gel of 3 mm. The thread pitch p of the external thread 8 also amounts to 1.0 mm. The thread length gl of the external thread 8 is slightly larger than the thread immersion length gel. The furrow d cut object for fastening to the external thread 8 of the threaded section 3 amounts to 0.5 mm in the object for fastening 18. Because of the furrow d of 0.5 mm, secure fastening of the fastening element 1 on the object for fastening 18 is possible and nevertheless only a low torque is required for turning the fastening element 1 when cutting the internal thread into the bore 19 manually when tapping the internal thread into the bore 19. The thread pitch p of 1.0 mm with an external diameter dga of the threaded section 3 of 3 mm ensures a secure and reliable form-fitting fastening of the fastening element 1 in the bore 19.

[0050] When considered as a whole, important advantages are associated with the inventive fastening element 1. Because of the fixation device 9 on the mounting section 5, fixation parts can be fastened on the fastening element 1 particularly easily because the mounting section 5 is arranged outside of the bore 19 after being fastened onto the bore 19 and is therefore readily accessible. The insertion section 2 does not have a threadless tip so that in this way essentially the entire external thread of the threaded section 3 can serve the purpose of form-fitting fastening inside of the bore 19, and the bore 19 is utilized completely for form-fitting fastening of the fastening element 1 in the region having a constant diameter of the bore 19.

[0051] FIGS. 5 and 6 illustrate another exemplary embodiment of a fastening element 51 each shown in a side view drawn to scale. The bolt-shaped fastening element 51 comprises an insertion section 52 for insertion along a longitudinal axis 53 into a bore on an object for fastening (not shown) and a mounting section 54 for arrangement outside of the bore and with an interface geometry 55 formed as a round hexagon socket for applying a torque to the fastening element 1. The insertion section 52 has a self-tapping threaded section 56 with a thread lead-in 57 for cutting, in particular tapping an internal thread into the bore and an external thread 58 connected to the thread lead-in 57 along the longitudinal axis 53 for being screwed into the internal thread. The external thread 58 has a constant external diameter dga of 5.7 mm along the longitudinal axis 53, a constant core diameter dgk of 3.96 mm, a constant thread height h of 0.87 mm, where h=0.5 (dgadgk), a constant flank angle of 60 and a constant thread pitch p of 1.0 mm. The thread lead-in 57 has an increasing external diameter along the longitudinal axis 53 which increases steadily from a value equal to the core diameter dgk of the external thread 58 up to a value equal to the external diameter dga of the external thread 58. The external thread is thus continuously connected to the thread lead-in 57. The length of the usable region of the thread lead-in 57 along the longitudinal axis 53 amounts to 1.13 mm, i.e., it is 1.13 times the thread pitch p of the external thread 58.

[0052] The thread lead-in 57 and the external thread 58 have a non-friction coating which reduces the friction between the thread lead-in 57 and/or the external thread 58 and the internal thread on the bore during the tapping and screwing. In addition, the external thread 58 has an adhesive coating, which increases the adhesion between the external thread 58 and the internal thread on the bore after the end of the screwing process in order to thereby reduce the risk of loosening of the fastening element 51 out of the bore.

[0053] The threaded section 56 has a thread length of 2.5 mm in the direction of the longitudinal axis 53. The one-piece fastening element 51 and thus also the external thread 58 are made of an inductively hardened stainless steel with a material hardness of 1,000 MPa.

[0054] The mounting section 54 has a collar 59 on which a sealing element can be arranged which seals the bore and/or the interspace between the bore and the fastening element with respect to the surroundings after the fastening element has been fastened onto the object for fastening. For secure sealing, the collar 59 has a stop 60 which comes to a stop against the edge of the bore when the fastening element 51 is screwed in and thereby secures the depth of penetration so that the sealing element is clamped in a defined manner between a peripheral shoulder 61 on the mounting section 54 and the object for fastening.

[0055] The mounting section 54 additionally has a fixation device 62 for fixation of a fixation part (not shown). The fixation device 54 is designed as an add-on external thread with an external diameter of 8 mm by means of which the fixation part can be screwed into the fastening element 51.

[0056] To produce the fastening element 51, the interface geometry 55 is applied to a semifinished product by a shaping method and a self-tapping thread is applied to a semifinished product with a rolling method to create the threaded section 56. Then a bevel 63 is created on the front end face of the semifinished product by a milling process wherein the self-tapping thread and the bevel 63 overlap one another to form the thread lead-in 57 and the external thread 58.

[0057] The bevel angle of the bevel 63 amounts to 52.5. Under some circumstances, the bevel also permits facilitated insertion of the fastening element into the bore. The diameter of the bore is greater than the core diameter dgk of the external thread 58 and smaller than the external diameter dga of the external thread 58. The internal diameter dgi of the bevel amounts to 3.5 mm at its start.

[0058] The internal thread shaped by the thread lead-in 57 in the bore of the object for fastening and the external thread 58 mesh with one another with a radial cut of 0.4 mm. The bore here is preferably embodied as a blind hole with a bore length of 5.7 mm, for example. The external thread 58 is then screwed into the object for fastening with a thread immersion length of 4 mm, for example. The thread immersion length here is determined by the stop 60.

[0059] This invention has been described on the basis of the exemplary embodiment as a fastening element for a grating, a line or a rail. However, it should be pointed out that the inventive fastening element is also suitable for other purposes. Furthermore, all the features of the various exemplary embodiments can be combined with one another in any form.