Connecting element, arrangement comprising a connecting element, and method for connecting at least two workpieces

Abstract

The invention relates to a connecting element for being pressed into a pre-drilled workpiece or for being punched into a non-pre-drilled workpiece, the connecting element comprising: a press-in portion; a contact surface which, after the pressing-in process, bears against a surface of the workpiece; a through-hole which extends completely through the connecting element and which is intended for screwing in a thread-forming screw, wherein the through-hole has at least two portions having different inner diameters, namely a first portion having a smaller inner diameter for forming a thread by means of the thread-forming screw, and a second portion having a larger inner diameter, wherein the larger inner diameter is greater than the outer diameter of the thread-forming screw, and wherein a length of the second portion is between 0.5 times and 5 times, in particular between 0.7 times and 1.5 times, the shank diameter or nominal diameter of the thread-forming screw.

Description

[0001] Connecting element, arrangement with a connecting element and method for joining at least two workpieces

[0002] The invention relates to a connecting element for joining to or being placed against a first workpiece, comprising a contact surface which, after joining or being placed against, rests against a surface of the first workpiece, a through-hole which completely passes through the connecting element and which is provided for screwing in a self-tapping screw. The invention also relates to an arrangement with a connecting element and a method for joining at least two workpieces.

[0003] The invention aims to improve a connecting element, an arrangement and a method for joining at least two workpieces.

[0004] According to the invention, a connecting element with the features of claim 1, an arrangement with the features of claim 6, and a method with the features of claim 10 are provided for this purpose. Advantageous embodiments of the invention are specified in the respective dependent claims.

[0005] A connecting element for joining or attaching to a first workpiece comprises a contact surface that, after joining, rests against a surface of the first workpiece, and a through-hole that completely passes through the connecting element and is designed for screwing in a self-tapping screw. The through-hole has at least two sections with different diameters. A first section of the through-hole has a smaller inner diameter for cutting a thread using the self-tapping screw. A second section of the through-hole has a larger inner diameter, wherein the larger inner diameter is larger than the outer diameter of the self-tapping screw, and wherein the length of the second section is 0.5 to 5 times, in particular 0.7 to 1.5 times, the shank diameter or nominal diameter of the self-tapping screw.

[0006] The second section of the through-hole, with its larger inner diameter, provides space for the expansion zone of the self-tapping screw. This allows the screw to be tightened to its hyperelastic limit, as the section of the screw located in the second section of the fastener with the larger inner diameter can expand without adversely affecting or damaging the screw. This section can be threaded or have a smooth outer circumference. Sufficient insertion depth, combined with a suitable pilot hole diameter, ensures that the thread cut into the first section of the through-hole by the self-tapping screw is not adversely affected.The inventors discovered that when using conventional press-fit elements in conjunction with self-tapping screws and tightening the self-tapping screws to the point of over-elasticity, the thread of the self-tapping screw is damaged. Such damage typically occurs when only small clamping thicknesses are involved, for example, when joining sheet metal. Surprisingly, these problems associated with tightening the self-tapping screws to the point of over-elasticity were solved by incorporating a through-hole into the fastener with at least two sections of different inner diameters. A first section with a smaller inner diameter serves to cut a thread using the self-tapping screw, and a second section with a larger inner diameter, where the larger inner diameter is greater than the outer diameter of the self-tapping screw, serves to provide an expansion zone for the self-tapping screw.The fastener according to the invention, in combination with a self-tapping screw, makes it possible, after cutting a thread into the through-hole of the fastener, to tighten the self-tapping screw to the overelastic range without deforming the self-tapping screw, its thread, and / or the thread cut by the self-tapping screw, or otherwise adversely affecting it. Self-tapping screws, or screws in general, are tightened to the overelastic range, for example, when torque-angle controlled tightening or yield-limit controlled tightening is performed. In this process, the gradient of torque and angle of rotation is measured. As long as the screw deforms within the elastic range, the gradient remains essentially constant. When the yield strength is reached and the screw material begins to yield, this gradient decreases significantly.The tightening of the screw is then stopped. Yield-limit controlled tightening of screws, especially self-tapping screws, offers significant advantages with regard to the achievable preload level of a bolted joint. Considerable benefits are also generated during assembly in the elastic range. The increased elongation of the screw significantly improves the joint quality. Settling after assembly is reduced due to the higher elongation of the screw. Thus, significantly higher residual preload forces can be maintained during operation of the bolted joint after assembly. This allows for the use of fewer and / or lighter screws and fasteners, thus promoting lightweight construction. The fastener according to the invention enables the tightening of a self-tapping screw, with a thread cut into the fastener, right up to the over-elastic range.

[0007] In a further development of the invention, the connecting element has a connecting section which is designed for pressing into a pre-drilled first workpiece, for punching into a non-pre-drilled first workpiece or for welding onto a pre-drilled or non-pre-drilled first workpiece.

[0008] In a further development of the invention, the connecting element is designed to be placed against a first workpiece with a contact surface. Consequently, the connecting element can be designed as a nut into which a thread is cut, which rests against the first workpiece and, in the assembled state, is pressed against the first workpiece by means of the threaded screw.

[0009] The problem underlying the invention is also solved by an arrangement with a connecting element according to at least one of the preceding claims and a threading screw, wherein the threading screw is arranged section by section in the through-bore of the connecting element, wherein a thread is cut into the first section of the through-bore with smaller diameter by means of the threading screw and wherein an annular gap lies between an inner wall of the second section of the through-bore and the outer circumference of the threading screw.

[0010] In the arrangement according to the invention, the connecting element can be pressed or stamped into a first workpiece, or it can simply rest against the first workpiece. A second workpiece is then connected to the first workpiece by means of the self-tapping screw. In the connected state, the self-tapping screw engages in a thread that was cut into the first section of the through-hole when the connecting element was screwed into the through-hole by means of the self-tapping screw. An annular gap is then arranged between the inner wall of the second section of the through-hole and the outer circumference of the self-tapping screw.With the connecting element according to the invention, it is possible to tighten the self-tapping screw up to the hyperelastic range without deforming the self-tapping screw, its thread, and / or the grooved thread, or otherwise adversely affecting it, since the section of the shank arranged in the second section of the through-hole, regardless of whether it is threaded or has a smooth outer circumference, can expand freely in the longitudinal direction and rotate about the central axis of the self-tapping screw. Significant advantages are also generated when assembling in the elastic range, as previously discussed. The self-tapping screw can also be designed as a press-fit screw, a self-drilling screw, or a punch-in screw.

[0011] In a further development of the invention, the threading screw is arranged without play in the thread which has been cut into the first section of the through-hole by means of the threading screw.

[0012] In a further development of the invention, both the first section of the through-hole with smaller diameter and the second section of the through-hole with larger diameter are arranged on the same side of the first workpiece.

[0013] In a further development of the invention, starting from a surface of the first workpiece that is facing away from the second workpiece, first the second section of the through-hole with a larger diameter and then the first section of the through-hole with a smaller diameter are arranged.

[0014] The problem underlying the invention is also solved by a method for connecting at least two workpieces with at least one connecting element according to the invention and at least one self-tapping screw, wherein the connecting element is connected to a first workpiece or is placed against the first workpiece, and at least a second workpiece is connected to the first workpiece by means of the self-tapping screw by screwing the self-tapping screw into the connecting element and wherein the self-tapping screw screwed into the connecting element is tightened to the hyperelastic range or to the elastic range.

[0015] The inventive method allows self-tapping screws to provide greater holding forces within a bolted joint. This means that the size of the self-tapping screws can be smaller compared to a combination of self-tapping screws with conventional fasteners, or fewer self-tapping screws and fasteners can be used without adversely affecting the strength of the joint. The inventive method is therefore particularly suitable for lightweight construction of structures in which at least two workpieces are joined together using fasteners and self-tapping screws. Significant advantages are generated both when tightening into the hyperelastic range and when tightening into the elastic range, as previously discussed. In a further development of the invention, yield-limit controlled tightening is performed when tightening the self-tapping screw.

[0016] With the method according to the invention, self-tapping screws can be tightened in a yield-limit controlled manner without having to fear that the self-tapping screw, a thread of the self-tapping screw and / or a thread cut into a connecting element by means of the self-tapping screw will be deformed or adversely affected in any other way.

[0017] In a further development of the invention, tightening the threading screw is carried out using a torque-controlled and / or angle-controlled process.

[0018] Significant advantages are also generated when tightening the threaded screw using torque control and / or angle control, as previously discussed.

[0019] Further features and advantages of the invention will become apparent from the claims and the following description of preferred embodiments of the invention in conjunction with the drawings. Individual features of the different embodiments described in the description and / or illustrated in the drawings can be combined with one another in any way without exceeding the scope of the invention. The drawings show:

[0020] Fig. 1 shows a view of a connecting element according to the invention in a first embodiment from a low angle,

[0021] Fig. 2 shows a sectional view of an arrangement with the connecting element of Fig. 1.

[0022] Fig. 3 shows a view of the cut connecting element from Fig. 2 from a low angle.

[0023] Fig. 4 shows a connecting element according to a second embodiment of the invention, viewed obliquely from below.

[0024] Fig. 5 shows a sectional view of the connecting element of Fig. 4.

[0025] Fig. 6 shows the cut-away connecting element of Fig. 5 from a bottom oblique angle, Fig. 7 shows a connecting element according to a third embodiment of the invention from a bottom oblique angle.

[0026] Fig. 8 shows a sectional view of the connecting element of Fig. 7.

[0027] Fig. 9 shows a view of the cut connecting element of Fig. 8 from a low angle,

[0028] Fig. 10 shows a connecting element according to a fourth embodiment of the invention, viewed obliquely from above.

[0029] Fig. 11 shows a sectional view of the connecting element of Fig. 10.

[0030] Fig. 12 shows a view of the cut connecting element of Fig. 11 from a low angle,

[0031] Fig. 13 shows a view of a connecting element according to the invention in a fifth embodiment from a low angle.

[0032] Fig. 14 shows a sectional view of the connecting element of Fig. 13.

[0033] Fig. 15 shows a view of the cut connecting element of Fig. 14 from a low angle,

[0034] Fig. 16 shows a view of a connecting element according to a sixth embodiment of the invention from an oblique angle above,

[0035] Fig. 17 shows a sectional view of the connecting element of Fig. 16.

[0036] Fig. 18 shows a view of the cut connecting element of Fig. 17 from a diagonal top view,

[0037] Fig. 19 shows a sectional view of an arrangement with the connecting element of Fig. 16.

[0038] Fig. 20 shows a view from below of a connecting element according to a seventh embodiment of the invention, Fig. 21 shows a sectional view of the connecting element of Fig. 20.

[0039] Fig. 22 shows a view of the cut connecting element of Fig. 21 from a diagonal top view,

[0040] Fig. 23 shows an arrangement with a connecting element according to Fig. 1 ,

[0041] Fig. 24 shows an arrangement with a connecting element according to Fig. 13,

[0042] Fig. 25 shows an arrangement with a connecting element according to Fig. 7 and

[0043] Fig. 26 shows an arrangement with a connecting element according to Fig. 10.

[0044] Fig. 1 shows a connecting element 10 according to a first embodiment of the invention. The connecting element 10 is formed in one piece and has a lower end 12 and an upper end 14. A through-opening 16 extends between the lower end and the upper end. At the lower end 12, a stamped design with a circular stamped collar 18 is provided, which surrounds the through-opening 16. Radially outside the stamped collar 18, a bearing projection 20 is provided. The bearing projection 20 has a polygonal shape. From the bearing collar 20 towards the upper end 14, the connecting element 10 initially has a polygonal shape, which then transitions into a circular cylindrical shape.

[0045] The connecting element 10 is placed onto a first workpiece, which is typically a sheet metal part, during the joining process. The first workpiece is positioned between a die and the connecting element 10. When the connecting element with the punch collar 18 is pressed against the first workpiece, a circular through-hole corresponding to the outer diameter of the punch collar 18 is punched out in the first workpiece. The die then deforms the punch collar 18 radially outwards, so that sections of the first workpiece are positioned between the deformed punch collar 18 and further sections of the connecting element 10. This creates a positive-locking connection between the connecting element 10 and the first workpiece.It is readily known to those skilled in the art how fasteners are connected to workpieces, particularly sheet metal workpieces, and how the fasteners are then held in place on the workpieces. After the fastener 10 is attached to the first workpiece, a second workpiece can be attached to the first by inserting a self-tapping screw through a through-hole in the second workpiece and then screwing it into the through-hole 16 of the fastener 16.

[0046] Fig. 23 shows a sectional view of an arrangement according to the invention with the connecting element 10 of Fig. 1. Fig. 2 also shows an arrangement with the connecting element 10 of Fig. 1; in contrast to Fig. 2, in Fig. 23 the self-tapping screw 26 has been screwed into the connecting element 1 to such an extent that the underside of the head of the self-tapping screw 26 rests against a surface of the second workpiece 24. The second workpiece 24 is thereby pressed against the first workpiece 22.

[0047] As can be seen in Fig. 23, in the first section 28 of the through-hole 16, the self-tapping screw engages in the thread cut into the first section 28. In the second section 30 of the through-hole 16, however, there is an annular gap 31 between an inner wall of the second section 30 of the through-hole 16 and an outer circumference of the self-tapping screw 26. The thread of the self-tapping screw 26 extends to just before the underside of the head of the self-tapping screw 26, which can be seen from the reduction in diameter of the shank of the self-tapping screw 26 just before the underside of the head of the self-tapping screw 26. Fig. 2 shows a sectional view of an arrangement with the connecting element 10 of Fig. 1. A first workpiece 22 in the form of a sheet metal part is shown schematically in Fig. 2. A second workpiece 24 and a self-tapping screw 26 are also shown schematically.

[0048] In Fig. 2, the connecting element 10 has been stamped into the first workpiece 22. For the sake of clarity, the deformation of the stamping collar 18 and the positive-locking connection between the first workpiece 22 and the connecting element 10 are not shown. The second workpiece 24 is pre-drilled and also made of sheet metal. The first workpiece 22 and the second workpiece 24 are positioned on top of each other, and a through-hole in the second workpiece 24 is aligned with the through-hole 16 in the connecting element 10. The self-tapping screw 26 is also shown schematically in Fig. 2 and, in particular, is considerably shorter than in a real embodiment. The self-tapping screw 26 has an outer diameter A in the area of ​​its shank. The self-tapping screw 26 is provided with a screw head that has a drive mechanism (not shown in Fig. 2) for screwing the self-tapping screw 26 into the through-hole 16.

[0049] The sectional view in Fig. 2 shows that the through-hole 16 has a first section 28 with a diameter B that is smaller than the outer diameter A of the shank of the self-tapping screw 26. This diameter B is also referred to as the pilot hole diameter. The through-hole 16 further has a second section 30 whose inner diameter C is larger than the outer diameter A of the shank or the outer diameter of the thread of the self-tapping screw 26. Starting from the first workpiece 22 upwards, i.e., starting from the surface of the first workpiece 22 facing away from the second workpiece 24, in the screw-in direction of the self-tapping screw 26, the second section 30 is arranged first, followed by the first section 28.When the threading screw 26 is positioned and fastened, it first moves through the through-hole in the second workpiece and into the second section 30, and then into the first section 28 to cut a thread. The second section 30 and the first section 28 are located on the same side of the first workpiece 22. A transition section 32, which has a frustoconical shape, is arranged between the first section 28 and the second section 30. A frustoconical inlet section 34 is arranged before the start of the second section 30. At the end of the first section 28 opposite the second section 30, a frustoconical outlet section 36 and then a circular cylindrical end section 38 are arranged.

[0050] When the self-tapping screw 26 is screwed into the through-hole 16, the shank of the self-tapping screw 26 is rotated, and a thread is cut into the inner wall of the first section 28 by means of the external thread on the shank of the self-tapping screw 26. The inner wall of the second section 30, however, does not contact the outer wall of the shank of the self-tapping screw 26. When the self-tapping screw 26 is fully screwed into the through-hole 16, the external thread on the shank of the self-tapping screw 26 engages in the inner wall of the first section 28, or rather, in a thread that has been cut into the inner wall of the first section 28 by the self-tapping screw 26.

[0051] In the area of ​​the second section 30, an outer wall of the shaft or an outer boundary of the thread of the threading screw 26 is spaced apart from the inner wall of the first section 28, so that an annular gap is formed between the outer circumference of the threading screw 26 and the inner wall of the second section 30. A lower surface of the head of the threading screw 26, shown at the top in Fig. 2, rests on a surface of the second workpiece 24 and clamps the second workpiece 24 against the first workpiece 22.

[0052] Viewed axially, the length of the second section 30 is equal to or greater than the diameter of the shaft of the threading screw 26. In the axial direction, the length of the transition section 32 is very small compared to the length of the second section 30. The transition section 32 serves only to bridge the diameter difference between the second section 30 and the first section 28. According to the invention, the transition section 32 can also be omitted. This also applies to the inlet section 34, the transition section 36, and the end section 38.

[0053] When the self-tapping screw is screwed in, a section of the shank of the self-tapping screw 26 lies within the second section 30 of the through-bore 16 and does not contact the inner wall of the through-bore 16 in the second section 30. This section of the self-tapping screw can have a thread or a smooth outer wall. According to the invention, it is preferred that the thread of the self-tapping screw extends almost to the underside of the head of the self-tapping screw 26.

[0054] When the self-tapping screw 26 is tightened relative to the connecting element 10 into the hyperelastic range, the section of the screw shank located within the second section 30 of the through-hole 16 can be twisted and also stretched axially. Consequently, the deformation of the screw shank into the hyperelastic range occurs predominantly in the section of the screw shank located within the second section 30 of the through-hole 16. This ensures that tightening into the hyperelastic range of the screw 26 does not cause any damage to the screw shank due to elastic and plastic deformation, particularly in the unthreaded portion of the screw shank.The unthreaded portion of the thread of the self-tapping screw 26 and / or a section of the shank of the self-tapping screw 26 with a smooth outer circumference are located in the second section 30 of the through-hole 16 of the connecting element 10. A sufficient thread engagement depth of the self-tapping screw 26, determined by the length of the first section 28 of the through-hole of the connecting element 10, in conjunction with a suitable pilot hole diameter B in the connecting element 10, ensures that the formed thread is not deformed or otherwise adversely affected.

[0055] Surprisingly, by providing the second section 30 of the through-hole 16 of the connecting element 10, it is possible to tighten the self-tapping screw 26 reliably up to the hyperelastic range without damaging or adversely affecting the unthreaded area of ​​the thread of the self-tapping screw 26 or the section of the shank of the self-tapping screw 26 that is located in the second section 30 of the through-hole 16 of the connecting element 10.

[0056] Fig. 3 shows the cut connecting element 10 of Fig. 2 in a view from a slant below.

[0057] Fig. 4 shows a connecting element 50 according to a second embodiment of the invention. The connecting element 50 is provided with a punch collar 52, which is pressed into an unperforated workpiece, in particular a sheet metal part, thereby punching out a through-hole in the workpiece. The punch collar 52 is then deformed mainly radially outwards by a suitable die, so that sections of the workpiece are positively connected to the connecting element 50. It is readily known to those skilled in the art how the connecting element 50 behaves in the area of ​​the punch collar 52 when pressed or punched into a workpiece.

[0058] Fig. 5 shows a sectional view of the connecting element 50 of Fig. 4. It can be seen that a through-hole 56 of the connecting element 50 has a first section 28 and a second section 30, the second section 30 having a larger diameter and the first section 28 a smaller diameter. The diameters of the two sections 28, 30 of the through-hole 56 are dimensioned such that the diameter of the second section 30 is larger than the outside diameter of the shank of a self-tapping screw intended for screwing into the connecting element 50. The diameter of the first section 28, on the other hand, is smaller than the outside diameter of the shank of the self-tapping screw. Thus, by screwing a self-tapping screw into the through-hole 56, an internal thread can be cut into the first section 28.

[0059] In the axial direction, the length of the second section 30 is 0.5 to 5 times, in particular 0.7 to 1.5 times, the shank diameter or nominal diameter of the self-tapping screw. A section of the shank of the self-tapping screw located in the region of the second section 30 thus serves as an expansion zone. This allows for the reliable, over-elastic tightening of a self-tapping screw in the through-hole 56 of the connecting element 50 using the connecting element 50 and a suitable self-tapping screw. Furthermore, the through-hole 56 is designed in the same way as the through-hole 16 of the connecting element 10 in Figures 1 to 3, so the corresponding features will not be explained again.

[0060] Fig. 6 shows a view of the cut connecting element 50 of Fig. 5 from a low angle.

[0061] Fig. 25 shows an arrangement with the connecting element 50 according to the invention from Figs. 4 to 6 and a self-tapping screw 26, as well as a first workpiece 22 in the form of a sheet metal part and a second workpiece 24, also in the form of a sheet metal part. The self-tapping screw 26 has been screwed into the through-hole 56 of the connecting element 50 and has thereby cut a thread into the first section 28 of the through-hole 56. In a second section 30 of the through-hole 56, there is an annular gap 31 between the inner wall of the through-hole 56 in the second section 30 and the outer circumference of the self-tapping screw 26. A head of the self-tapping screw 26 pre-tensions the second workpiece against the first workpiece 22. The connecting element 50 is riveted to the first workpiece 22, in the manner of a rivet nut known per se. Fig. 7 shows a connecting element 60 according to a third embodiment of the invention.

[0062] The connecting element 60 is designed for punching into a workpiece and has an annular punch collar 62 on its underside for this purpose. An annular bearing projection 64 is provided radially outside the punch collar. When the connecting element 60 is pressed into a workpiece, in particular a sheet metal part, a through-hole is first punched out by means of the punch collar 62. The punch collar is then formed and bent predominantly radially outwards by means of a suitable die, so that the sections of the workpiece surrounding the punched through-hole are positively locked to the connecting element 60. It is of course known to those skilled in the art how the connecting element 60 is deformed in the region of its underside and then positively locked to a workpiece.

[0063] Fig. 8 shows a sectional view of the connecting element 60 of Fig. 7. A through-hole 66 of the connecting element 60 is provided for screwing in a self-tapping screw and is essentially identical to the through-holes 16, 56 of the connecting elements 10, 50. A second section 30 of the through-hole 66 has a diameter that is larger than the outer diameter of the shank of a self-tapping screw 26, which is screwed into, or is intended to be screwed into, the through-hole 66. A first section 28 of the through-hole 66 has a diameter that is smaller than the outer diameter of the shank of the self-tapping screw 26, so that a thread can be cut into the first section 28 of the through-hole 66 by the self-tapping screw 26.

[0064] In the axial direction, the length of the second section 30 is 0.5 to 5 times, in particular 0.7 to 1.5 times, the shank diameter or nominal diameter of the threading screw 26. A section of the shank of the threading screw 26, which in the screwed state is arranged within the second section 30, can thus serve as an expansion area of ​​the shank of the threading screw 26, so that the threading screw 26 can be tightened reliably up to the overelastic range.

[0065] Fig. 9 shows a view of the cut connecting element 60 of Fig. 8 from a low angle.

[0066] Fig. 10 shows a connecting element 70 according to a fourth embodiment of the invention.

[0067] The connecting element 70 is provided with a through-hole 76 and has an axially extending knurling 72 on its outer surface. The connecting element 72 is pressed into a pre-drilled workpiece, whereby the knurling 72 presses into the inner wall of the hole in the workpiece during pressing. The connecting element 70 is pressed in until the underside of a head 74 of the connecting element 70 rests on a surface of the workpiece.

[0068] This allows the connecting element 70 to be anchored in a pre-drilled workpiece in a rotationally fixed manner.

[0069] Fig. 11 shows a sectional view of the connecting element 70. It can be seen that the through-hole 76 is constructed in the same way as the through-holes 16, 56, 66 of the connecting elements 10, 50, 60 already described. Specifically, in the illustration of Fig. 11, the self-tapping screw 26 would be screwed into the through-hole 76 from above. The through-hole 76 has a second section 30, the inner diameter of which is larger than the outer diameter of the shank of the self-tapping screw 26. A first section 28 of the through-hole 76 has an inner diameter that is smaller than the outer diameter of the shank of the self-tapping screw 26, so that a thread can be cut into the first section 28 by means of the self-tapping screw. The axial length of the second section 30 is 0.5 to 5 times, in particular 0.7 to 1.5 times, the shaft diameter or nominal diameter of the threading screw 26.A section of the shaft of the worm screw 26 located in the area of ​​the second section 30 can thus serve as an expansion area.

[0070] Fig. 12 shows a view of the cut connecting element 70 of Fig. 11 from a low angle.

[0071] Fig. 26 shows a sectional view of an arrangement comprising the connecting element 70 according to the invention from Figs. 10 to 12, a self-tapping screw 26, a first workpiece 22, and a second workpiece 24. The first workpiece 22 has a considerably greater thickness than the second workpiece 24. The connecting element 70 has been pressed into a through-hole in the first workpiece 22, such that the knurling 72 of the connecting element 70 rests against the inner wall of the through-hole in the first workpiece 22. The self-tapping screw 26 has been screwed into the connecting element 70 and has cut a thread in the first section of the through-hole 76 in the connecting element 70. In the second section of the through-hole, which has a larger diameter, there is an annular gap 31 between the outer circumference of the screw shank of the self-tapping screw 26 and the inner circumference of the through-hole. The screw head of the self-tapping screw 26 pre-tensions the second component 24 against the first component 22.

[0072] Fig. 13 shows a connecting element 80 according to a fifth embodiment of the invention. The connecting element 80 is provided with a through-opening 86 and with an axially extending knurling 82 at a lower end. Like the connecting element 70 of Fig. 10, the connecting element 80 with the knurling 82 is pressed into a previously prepared opening in a workpiece. The pressing is carried out until a support ring 84 on the connecting element 80 rests on a top surface of the workpiece.

[0073] Fig. 14 shows a sectional view of the connecting element 80 of Fig. 13. The through-opening 86 is designed in the same way as the through-openings 16, 56, 66, 76 of the connecting elements 10, 50, 60, 70, which have already been explained.

[0074] The threaded screw 26 would be screwed into the through-hole 86 from below, as shown in Fig. 14. The through-hole 86 has a second section 30, the inner diameter of which is larger than the outer diameter of the shank of the threaded screw 26. The through-hole 86 has a first section 28, the inner diameter of which is smaller than the outer diameter of the threaded screw 26. When the threaded screw 26 is screwed into the through-hole 86, a thread is cut into the first section 28. A section of the shank of the threaded screw 26, located in the second section 30, serves as an expansion section to allow the threaded screw to be tightened into the hyperelastic range.

[0075] Fig. 24 shows an arrangement with the connecting element 80 according to the invention from Figs. 13 to 15. The connecting element 80 was pressed into a through-hole of a first component 22. A self-tapping screw 26 was screwed into the through-hole of the connecting element 80, and the screw head of the self-tapping screw 26 presses a second workpiece 24 against the first workpiece 22. The self-tapping screw 26 cuts a thread into the first section of the through-hole 86 of the connecting element 80. In the second section of the through-hole, an annular gap 31 is located between an inner wall of the through-hole and the outer circumference of the screw shank or the outer diameter of the thread of the self-tapping screw 26.

[0076] Fig. 16 shows a connecting element 90 according to a sixth embodiment of the invention. The connecting element 90 is provided with a drive element 92 in the form of an external hexagon. A through-hole 96 extends through the connecting element 90.

[0077] Fig. 17 shows a sectional view of the connecting element 90 of Fig. 16. It can be seen that the through-hole 96 has a first section 28, which is provided for thread cutting by means of the self-tapping screw 26, see also Fig. 19. A second section 30 of the through-hole 96 has a larger diameter than the first section 28. In section 30, the diameter of the through-hole 96 is larger than the outer diameter of the screw shank or larger than the outer diameter of the thread of the self-tapping screw 26, see Fig. 19, so that in the assembled state, see Fig. 19, an annular gap 31 lies between the outer circumference of the screw shank or the outer diameter of the thread of the self-tapping screw 26 and the inner circumference of the second section 30 of the through-hole 96.

[0078] Fig. 18 shows the cut connecting element 90 of Fig. 17 in a view from an oblique top.

[0079] Fig. 19 shows an arrangement comprising the connecting element 90 of Figs. 16 to 18, a threading screw 26 screwed into the connecting element 90, a first workpiece 22, and a second workpiece 24. The head of the threading screw 26 presses the second workpiece 24 against the first workpiece 22. The connecting element 90 rests with an annular contact surface 94 (see Fig. 17) on the underside of the first workpiece 22, which is shown at the bottom in Fig. 19. The connecting element 90 is thus designed as a nut intended to rest against a workpiece. When the threading screw 26 cuts a thread into the through-hole 96 of the connecting element 90, the connecting element 90 can be held against rotation by its drive element 92.The first section of the through-hole 96 with a smaller diameter, into which a thread was cut by means of the threading screw 26, and the second section of the through-hole 96, in which there is an annular gap between the threading screw 26 and the inner wall of the second section (not visible in Fig. 19), are arranged on the same side of the first workpiece 22.

[0080] Fig. 20 shows a connecting element 100 according to a seventh embodiment of the invention in a bottom view. The connecting element 100 is designed as a weld nut and has a square cross-section on its underside, which faces the viewer in Fig. 20, and a weld projection 102 at each corner of the square cross-section. These weld projections 102 are metallurgically bonded to a first workpiece, for example by resistance welding. A through-hole 106 of the connecting element 100 is provided for screwing in a self-tapping screw.

[0081] In the sectional view of Fig. 21, it can be seen that the through-hole 106 of the connecting element 100 has a first section 28, which has a smaller diameter and is designed for thread cutting by means of the threading screw 26. Furthermore, the through-hole 106 has a second section 30, which has a larger diameter than the first section 28. In the assembled state, an annular gap exists in the region of the second section 30 between an outer circumference of the threading screw 26 and an inner circumference of the through-hole 106.

[0082] Fig. 22 shows a view of the cut connecting element 100 of Fig. 21 from an oblique top view.

Claims

Patent claims 1. Connecting element for connecting to or attaching to a first workpiece, comprising a contact surface which, after connecting or attaching, rests against a surface of the first workpiece, a through-hole which completely passes through the connecting element and which is provided for screwing in a thread-cutting screw, characterized in that the through-hole has at least two sections with different inner diameters, namely a first section with a smaller inner diameter for cutting a thread by means of the thread-cutting screw and a second section with a larger inner diameter, wherein the larger inner diameter is larger than the outer diameter of the thread-cutting screw and wherein the length of the second section is 0.5 to 5 times, in particular 0.7 to 1.5 times, the shank diameter or nominal diameter of the thread-cutting screw.

2. Connecting element according to claim 1, characterized in that a connecting section is provided which is designed for pressing into a pre-drilled first workpiece.

3. Connecting element according to claim 1, characterized in that a connecting section is provided which is designed for punching into a first workpiece that is not pre-drilled.

4. Connecting element according to claim 1, characterized in that a connecting section is provided which is designed for welding onto a pre-drilled or non-pre-drilled first workpiece.

5. Connecting element according to claim 1, characterized in that the connecting element is designed for placement against a first workpiece with the contact surface.

6. Arrangement comprising a connecting element according to at least one of the preceding claims and a self-tapping screw, wherein the self-tapping screw is arranged section by section in the through-bore of the connecting element, wherein a thread is cut into the first section of the through-bore with a smaller diameter by means of the self-tapping screw, and wherein between an inner wall of the There is an annular gap between the second section of the through-hole and the outer circumference of the threaded screw.

7. Arrangement according to claim 6, characterized in that the screw is designed as a press-fit screw, a drill-in screw or a punch-in screw.

8. Arrangement according to claim 6 or 7, characterized in that the connecting element is connected to or abuts a first workpiece, that a second workpiece is connected to the first workpiece by means of the threading screw, that the threading screw is screwed into the through-bore of the connecting element and engages in a thread which was cut into the first section of the through-bore when screwed into the through-bore of the connecting element, and that an annular gap is located between an inner wall of the second section of the through-bore and the outer circumference of the threading screw.

9. Arrangement according to claim 6, 7 or 8, characterized in that the threading screw is arranged without play in the thread which has been cut into the first section of the through bore by means of the threading screw.

10. Arrangement according to claim 8 or 9, characterized in that both the first section of the through-hole with smaller diameter and the second section of the through-hole with larger diameter are arranged on the same side of the first workpiece.

11. Arrangement according to claim 10, characterized in that, starting from a surface of the first workpiece which is facing away from the second workpiece, first the second section of the through-hole with a larger diameter and then the first section of the through-hole with a smaller diameter is arranged.

12. Method for connecting at least two workpieces with at least one connecting element according to at least one of the preceding claims 1 to 5 and at least one self-tapping screw, wherein the connecting element is connected to a first workpiece or is placed against the first workpiece and at least a second workpiece is connected to the first workpiece by means of the self-tapping screw by screwing the self-tapping screw into the connecting element, characterized by tightening the threaded screw inserted into the connecting element until it reaches the hyperelastic range.

13. Method according to claim 12, characterized in that tightening of the forming screw is carried out using yield point control.

14. Method according to claim 12, characterized in that tightening of the threading screw is carried out in a torque-controlled and / or angle-controlled manner.

15. Method for connecting at least two workpieces with at least one connecting element according to at least one of the preceding claims 1 to 5 and at least one self-tapping screw, wherein the connecting element is connected to a first workpiece or is placed against the first workpiece and at least a second workpiece is connected to the first workpiece by means of the self-tapping screw by screwing the self-tapping screw into the connecting element, characterized by tightening the self-tapping screw screwed into the connecting element in the elastic range.

16. Method according to claim 15, characterized in that tightening of the threading screw is carried out in a torque-controlled and / or angle-controlled manner.

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