Press-fit element, method for forming a press-fit connection and press-fit connection

Abstract

To form a press-fit connection (4) with a pre-drilled component (6), a press-fit element (2) has a head section (8) with a head support (16) and a compression collar (20) adjoining the head section (8) in a press-fit direction (12). The compression collar (20) has a base section (22) and a filling section (24), the filling section (24) adjoining the base section (22) by forming an internal step (26) oriented towards the central axis (10). This ensures reliable filling of an annular space (58) between a stamped collar (38) of a die (32) and a perforated wall (30) with collar material during the manufacturing process by solid forming of the collar material, thus guaranteeing good pull-out resistance, torsional torque, and watertightness.

Description

[0001] The invention relates to a press-fit element with the features of claim 1, a method for forming a press-fit connection and a press-fit connection.

[0002] Such a press-fit element and press-fit connection can be found, for example, in DE 10 2016 204 619 B4. The press-fit connection described therein has a high-strength component, in particular a high-strength sheet, into which the press-fit element is pressed. With such press-fit connections, the problem is that, due to the high strength, the component itself cannot be formed, or can only be formed with great difficulty.

[0003] For the purposes of this application, a high-strength component is understood to be a component with a strength greater than 600 MPa, in particular greater than 800 MPa, and preferably up to 2200 MPa. In addition to cold-formed steel, the component may also be made of hot-formed, press-hardened steel. The press-fit element used for this purpose, in particular a press-fit nut, typically has a strength of approximately 1000 MPa and specifically strength class FK 10. The (sheet) thickness, and thus the wall thickness, of the component is typically between 1.5 mm and 4 mm.

[0004] German patent DE 10 2016 204 619 B4 describes a specific process in which a compression collar of the press-fit element is simply pressed against the hole wall of the pre-drilled component by means of a bulk forming operation. No forming in the sense of crimping a compression collar or radial expansion involving tangential tensile stresses takes place. Furthermore, the component itself is not deformed due to its high strength.

[0005] Press-fit connections can be found, for example, in DE 24 41 977 C2 or DE 10 2012 220 033 A1. These documents describe press-fit nuts with a polygonal compression collar for anti-rotation protection. According to US 2007 / 0166128 A1, the hole in the component also has a polygonal circumference for additional anti-rotation protection.

[0006] Based on this, the invention aims to enable a reliable press-fit connection between a press-fit element and a particularly high-strength component in a process-reliable manner.

[0007] The problem is solved according to the invention by a press-fit element with the features of claim 1, by a method for producing a press-fit connection with the features of claim 13, and by a press-fit connection with such a press-fit element with the features of claim 20.

[0008] The advantages and preferred embodiments mentioned in connection with the press-fit element, the method or the press-fit connection are to be transferred to each other accordingly.

[0009] The press-fit element is primarily a press-fit nut. Besides a nut, it can also be a press-fit element with a through-hole, particularly without an internal thread. A thread-forming screw or a wire thread insert, for example, is later inserted into the through-hole.

[0010] The press-fit element is used to create a press-fit connection with a pre-drilled, and especially high-strength, component. The press-fit element extends along a central axis in the press-fit direction. This direction also defines a longitudinal direction. The press-fit element has a head section with a typically annular head bearing, which allows the press-fit element to rest against a top surface of the component during the press-fit connection process. A compression collar, also known as a forming collar, extends from the head section in the press-fit direction. During the press-fit connection process, a positive fit and / or frictional fit is created with a hole, specifically with a hole wall of the pre-drilled component, primarily through bulk forming.

[0011] For a reliable joining process, the compression collar has a base section adjoining the head part and a compression collar section extending further along its length, which is referred to as the filling section. The compression collar generally extends from the underside of the head part in the insertion direction and is roughly ring-shaped. Both sections are therefore also ring-shaped. The ring can have a circular or polygonal contour, for example, a hexagonal contour.

[0012] The filling section adjoins the base section, forming an internal step oriented towards the central axis. The base section generally has an axial base height extending in the insertion direction, from the head support to the step. Furthermore, the filling section generally has an axial filling height extending from the step to a forward end of the compression collar in the insertion direction.

[0013] The upper end of the base section, and thus the end of the compression collar, lies at the axial height of the head support and is therefore defined by the head support. The lower end of the compression collar is defined by the front, end-facing free end of the filling section.

[0014] In the production of the press-fit connection, the press-fit element, with its upsetting collar facing forward, is generally inserted into the hole of the component, which has a circumferential hole wall. Using a die with a front punch section, the upsetting collar is formed such that the collar material is pressed against the hole wall, specifically without the upsetting collar engaging the underside of the component. The front punch section is designed like a front stamping collar and will be referred to as such below. The component in question is, in particular, a high-strength component, specifically sheet metal with a strength as defined previously for high-strength components.

[0015] In the formation of the press-fit connection, analogous to the method described in DE 10 2016 204 619 B4, a bulk forming process is carried out in three spatial directions, so that the upsetting collar, and in particular the base section, is upset using the die. In this process, collar material is pressed against the hole wall to form an interference fit with the hole wall by bulk forming.

[0016] Therefore, no conventional forming process takes place, in which the upsetting collar is radially expanded outwards and engages the underside of the component from below. This bulk forming process essentially involves pressure forming of the collar material, similar to forging.

[0017] The descriptions of the design of the press-fit connection in DE 10 2016 204 619 B4 are hereby incorporated into the present application, in particular paragraphs 19 and 20 as well as 22 and 24.

[0018] Due to its stepped design with a base section and a filling section, the compression collar has a step on its radially inner side. A central interior space enclosed by the compression collar widens in a stepped fashion at the transition from the base section to the filling section. As a result, the filling section has a significantly thinner wall than the base section and is very delicate and thin overall. The particular advantage of this leading filling section with its thin wall is that the collar material (of the filling section) can penetrate deeper between the die and the hole wall, especially in a press-fit process where the compression collar does not initially, or does not fully, penetrate the hole of the component.The special design of the compression collar ensures that the collar material is reliably filled and compressed against the hole wall as completely as possible over the entire or at least almost the entire axial length (height) of the hole.

[0019] When creating the press-fit connection, the front filling section preferably penetrates a free circumferential annular space (gap) between the front embossing flange of the die and the hole wall to achieve the desired complete filling and compression over the entire axial length of the hole. This also means that the outer diameter of the front embossing flange is preferably smaller than the inner diameter of the hole, so that the annular gap exists.

[0020] For the forming process itself, the front embossed collar is pressed against the compression collar, and specifically against the step, in the opposite direction to the insertion direction. This results in bulk forming through displacement and the consequent flow of the material. The material flows radially, thus forming an interference fit with the hole wall. The material also partially deflects axially, so that the material flow also has an axial component, causing material to flow axially downwards in the insertion direction as well.

[0021] The design of the compression collar with its base section and filling section is based in particular on the consideration that, for the formation of the press-fit connection, the process often requires that the die, with its front embossed collar, is first inserted into the hole of the component from below, and that only subsequently is the press-fit element brought in from above using a suitable press ram and pressed against the die. This means that at the beginning of the press-fit process, the nut with the compression collar is not, or at least not completely, immersed in the hole. The radially outer, thin filling section now achieves the particular advantage described above: the filling section penetrates the free annular space between the hole wall and the front embossed collar, thus reliably forming the desired material compression with the hole wall over the entire axial length of the hole.

[0022] In the production of the press-fit connection, the preferred procedure is therefore such that the front embossed collar is first inserted into the hole, and then the press-fit element is pressed against the die from above. At the beginning of the press-fit process, the press-fit element is therefore not, or at least not completely, inserted into the hole; that is, at the beginning of the press-fit process, the head bearing does not rest on the top surface of the component. At the same time, at the beginning of the press-fit process, the component already rests with one underside on a support surface of the die designed as an annular shoulder. The annular shoulder forms a bearing surface of the die. The press-fit element is therefore axially displaced towards the component during the press-fit process, while the component is already supported on the die, specifically on the annular shoulder.Especially in such press-fit processes, the filling section ensures a reliable formation of a high-quality press-fit connection.

[0023] In a preferred embodiment, the fill height is in the range of 20% to 100%, and particularly in the range of 30% to 60%, of the base height. The fill height is preferably generally less than the base height. The overall height of the compression collar is preferably in the range of, for example, 1.5 mm to 4 mm. It preferably corresponds to the thickness of the component (sheet thickness) or is less than the thickness of the component. This thickness is generally preferably between 1 mm and 4 mm, and particularly in the range of 1.5 mm to 3 mm.

[0024] The wall thickness (width) of the base section and the fill section is each defined by a base thickness and a fill thickness. The base thickness and the fill thickness are each determined at half the base height and half the fill height, respectively.

[0025] The fill thickness is preferably in the range between 5% and 40%, and particularly in the range between 10% and 30%, of the base thickness. The fill section is therefore significantly thinner than the base section, allowing it to penetrate the annular gap (free annular space) between the front embossing band of the die and the hole wall.

[0026] In a preferred embodiment, the step has a radial step width, and the compression collar has a radial collar width at the height of the step, wherein the radial step width is in the range between 20% and 80%, and particularly in the range between 30% and 60%, of the radial collar width. The radial collar width at the axial height of the step comprises the radial step width and a radial width of the filling section at this axial height.

[0027] The radial step width generally refers to the extent of the step in the radial direction. The step is generally formed by a radially extending (ring-shaped) area between the base section and the filling section.

[0028] As a result, the step has a very large radial step width, so that an inner surface of the compression collar in the area of ​​the step is significantly offset radially outwards.

[0029] This step generally runs preferably parallel, or at least substantially parallel, to a horizontal plane oriented perpendicular to the longitudinal direction and thus also to the central axis. "Substantially parallel" is understood to mean an orientation at an angle of inclination, referred to as the step angle, of a maximum of + / - 20° and preferably of a maximum of + / - 10°.

[0030] In a preferred embodiment, the step is inclined outwards, so that it slopes outwards in the longitudinal direction. The step angle is particularly in the range between 1° and 15°, and preferably between 3° and 8°.

[0031] In a suitable embodiment, the base section and the filling section – in their undeformed initial state – transition seamlessly into one another on the outer surface. That is, the compression collar has no step or ridge on its outer circumferential side. Therefore, the base section and the filling section merge smoothly into one another on this outer circumferential side. According to a preferred embodiment, the base section and the filling section form a common outer circumferential side that runs parallel to the central axis. Alternatively, this common outer circumferential side is inclined at a conical angle, particularly outwards, to the central axis. The conical angle is, for example, in the range of only a few degrees (1°–10°).

[0032] As an alternative to this configuration, in which the base section and the filling section transition seamlessly into one another circumferentially, an outer surface of the filling section, or preferably the entire filling section (including an inner surface), is oriented at an angle to the base section and / or is inclined obliquely inwards at an external angle relative to the insertion direction, thus towards the central axis. This creates a kind of insertion ramp in the filling section, which facilitates the insertion of the compression collar into the hole. The outer surface, or the entire filling section, is inclined, for example, at an external angle of between 5° and 30°, and preferably between 10° and 20°.

[0033] The inner side of the compression collar, opposite the outer circumferential side, is generally oriented at an angle to the central axis, or at a greater angle than the outer circumferential side. The inner side slopes outwards. Therefore, an inner diameter defined by the compression collar widens in the direction of insertion.

[0034] The inner side of the compression collar in the area of ​​the filling section is hereinafter referred to as the lower inner section, and the inner side in the area of ​​the base section is hereinafter referred to as the upper inner section. The lower inner section is preferably inclined at a lower (inner) angle relative to the pressing direction, with this lower, inner angle of inclination being particularly in the range between 10° and 40°, and specifically between 15° and 30°. The lower inner section is in particular inclined outwards (positive lower angle of inclination). Alternatively, it can also be inclined inwards (negative lower angle of inclination).

[0035] The upper inner section is preferably inclined obliquely outwards at an upper (inner) angle of inclination, which is preferably in the range between 10°-40° and in particular between 15° and 30°.

[0036] Preferably, the lower inner section and the upper inner section run parallel to each other or at least largely parallel to each other and have, for example, angles of inclination that differ by a maximum of + / - 20°.

[0037] In a preferred embodiment, an upper wall section adjoins the upper inner surface, opposite to the insertion direction. This upper wall section has a steeper angle of inclination than the upper inner surface with respect to the insertion direction and can, for example, be cylindrical.

[0038] The steeper angle of the upper wall section offers the distinct advantage of creating a kind of recess, thus reducing the amount of material present in this area. This prevents material from being displaced inwards during the pressing process and, for example, deforming a thread formed there.

[0039] As mentioned at the beginning, the press-fit element is specifically a press-fit nut, which therefore has a through hole with an internal thread. Viewed in the press-fit direction, the internal thread ends, in particular, before the start of the base section. Specifically, the internal thread ends before or at the start of the upper wall section.

[0040] In general, in the fully formed press-fit connection, the head part with its head support rests directly on a top surface of the component and thus on a circumferential hole edge of the hole.

[0041] In a preferred embodiment, the compression collar, which forms an anti-rotation device, has a polygonal and, in particular, a hexagonal outer contour. Preferably, the entire head section has such a polygonal outer contour.

[0042] The hole in the component preferably has the same polygonal circumferential contour as the compression collar.

[0043] To form the press-fit connection, the following steps are preferably carried out – especially in addition to the previous explanations: According to a preferred embodiment, the component is first placed on the die, specifically on an annular shoulder of the die, so that the front embossing flange is inserted into the hole. The insertion element is then pressed against the die from above. The embossing flange designates and defines a predetermined embossing contour.

[0044] The front embossing collar preferably has a radially outwardly extending end face which, during the pressing process, is pressed against the step and exerts an axial forming force on it, resulting in the desired radial material displacement and deformation. The end face is preferably straight. Additionally or alternatively, it can be horizontal or slope outwards.

[0045] The end face preferably transitions via a transition area into a circumferential side of the front embossed band. The transition area is chamfered or rounded.

[0046] During the pressing-in process, the end face pushes the material of the compression collar upwards, causing the collar to be forced outwards against the edge of the hole. The transition area of ​​the die serves primarily to shape the joint, preventing the die from sticking to the press-fit connection and / or from breaking on a sharp edge. The collar material is redirected here, but not bent outwards. This is a process of the collar material flowing.

[0047] The dimensions of the front embossing band and the compression collar are coordinated, for example, in such a way that at the beginning of the pressing process, the filling section with its lower inner section hits the transition area and is reliably guided through it during the pressing process, so that the filling section can reliably penetrate into the circumferential gap between the front embossing band and the perforated wall.

[0048] The bulk forming of the upsetting collar is initiated by the die with its (straight) end face. When the component contacts the end face, the upsetting collar is compressed upwards and thus also flows radially towards the hole edge. This crimps the collar material between the hole edge and the die. The collar material flows around the radius formed on the outside and by the transition area. Conventional bending does not occur; that is, the die does not bend the material of the upsetting collar outwards.

[0049] During the formation of the press-fit connection, the end face acts on the step in the opposite direction to the press-fit direction. This causes a massive deformation and thus a flow of the collar material, so that it penetrates the gap, i.e., the circumferential annular or free space, and is pressed radially against the hole wall. Preferably, only an axial force component is exerted on the step. In particular, no radial expansion occurs.

[0050] In a further development, the end face is designed as an annular surface, which is bounded inwards towards the central axis by an axially projecting ring collar, also known as a contour collar. This collar prevents the displacement of collar material inwards towards the central axis. This ensures that the material of the compression collar is reliably pressed radially outwards against the hole wall.

[0051] In general, the geometries of the compression collar, the embossed band and the hole are matched to each other within tight tolerances, so that in the press-fit connection at least one and preferably all of the following properties are achieved: - The head rests directly on the top side of the component. - The press-fit element does not protrude beyond the underside of the component. - The underside is not reached by the compression collar. The compression collar pressed against the hole wall extends at most over the entire, or at least nearly the entire, axial length of the hole wall. Nearly the entire length is understood to mean a deviation of no more than 10%, and preferably no more than 5%. Preferably, however, the compression collar extends over the entire length. - The component is undeformed in the area of ​​the hole, i.e., a hole edge on the underside is not bent over / pulled up, so that a part of the compression collar may engage behind the bent part. - The component is a high-strength component. - The component is a pre-drilled component

[0052] The hole is formed before the pressing process by a suitable hole-forming operation, in particular by shearing (punching). For components made of hot-formed steel, the hole-forming operation can optionally take place before or after the heat treatment of the component. Alternatively, a laser cutting operation can also be used. Furthermore, the hole can be created in the component by mechanical processing such as milling or drilling. The edges of the hole run essentially parallel to the central axis. Particularly in the punching process, when a punch is driven through the component in the pressing direction, a slight tearing or chipping occurs on the underside at one edge of the hole wall, so that the hole wall widens radially at a slight angle of inclination (a few degrees) in that area (i.e., only in the lower half or the lower two-thirds).Furthermore, the surface of the hole wall in this torn-out section, i.e., at the fracture surface, is roughened. This widening, combined with radial compression against the hole wall, achieves sufficient pull-out resistance in the axial direction opposite to the insertion direction.

[0053] The component in question is, in particular, a press-fit nut. Alternatively, it can also be a press-fit bolt. In the latter case, a shank, especially a threaded shank, is attached to the head and extends along the central axis in the press-fit direction. The shank is surrounded by the compression collar with its specific geometry, comprising a base section and a joining section, typically leaving an annular gap.

[0054] An embodiment of the invention is explained in more detail below with reference to the figures. These show: Fig. 1 a cross-sectional representation to illustrate the process for forming the press-fit connection with a press-fit nut as a press-fit element, a pre-drilled component and with a die at the beginning of the process, in which the component is placed on the die and the press-fit nut is subsequently pressed in, Fig. 2 a cross-sectional representation analogous Fig. 1, in the further course of the pressing process, when the press-fit nut hits the die, Fig. 3 Another cross-sectional view in the further course of the pressing process, in which the press-in nut is fully pressed in, Fig. 4. A top view of the press-fit nut, Fig. 5 a view of the press-fit nut from below, Fig. 6 an enlarged representation of the in the Fig. 1. Section marked with A Fig. 7 an enlarged representation of the in the Fig. 1 section designated B as well as Fig. 8 an analogous illustration Fig. 6 of an alternative variant.

[0055] In the figures, parts that have the same effect are marked with the same reference symbols.

[0056] The press-fit element shown in the figures is designed as a press-fit nut 2. This serves to form a [missing information - likely a specific feature or characteristic] in the Fig. 3 recognizable press-fit connection 4 with a pre-drilled component 6 designed as sheet metal by means of a press-fit process, as is used in the Fig. 1 to 3 are described.

[0057] The press-fit nut 2 generally has a head section 8 which extends along a central axis 10 in a press-fit direction 12, which also defines a longitudinal direction. The press-fit nut 2 has a central through-hole in which an internal thread 14 is formed. In the press-fit direction 12, a head bearing 16 is formed on the underside of the head section 8, forming a step. This bearing surface is a circumferential, annular contact area. In the press-fit connection 4, the head bearing 16 rests on a top surface 18 of the component 6.

[0058] Starting from the head support 16, a circumferential and ring-shaped compression collar 20 extends in the pressing direction 12. This is divided into an upper base section 22 and a lower filling section 24. The two sections 22, 24 merge into each other, forming a step 26.

[0059] The exact geometry of the press-fit nut 2 in the area of ​​the compression collar 20 is shown below with reference to the enlarged representation of the Fig. 6 explained in more detail.

[0060] Component 6 is designed as a high-strength, pre-drilled steel sheet with strengths as defined previously. It has a hole 28 with a hole wall 30, into which the press-fit nut 2 is pressed.

[0061] The pressing process is carried out using a die 32. Its structure is also particularly evident from the enlarged illustration according to Fig. 7. The die 32 has an annular shoulder 34 at its front end, on which the component 6 rests with its underside 36 during the pressing process. In the central inner area, the die 32 has a front embossing collar 38, which protrudes opposite to the pressing direction 12 and, during the pressing process, plunges into the hole 28 from the underside 36.

[0062] The embossed band 38 has an end-face ring surface 40 (end surface) which transitions via a particularly rounded transition area 42 into an outer circumferential side 44 of the embossed band 38, to which the horizontally extending ring shoulder 34 then adjoins. In the exemplary embodiment, the transition area 42 has a comparatively large radius. Alternatively, the transition area is more angular and has a smaller radius.

[0063] Radially inwards, a ring collar 46, projecting axially in the opposite direction to the insertion direction 12, adjoins the end face of the ring surface 40.

[0064] In the exemplary embodiment, the die 32 is made of solid material. Alternatively, it can also be hollow inside, particularly for inserting a press-fit bolt.

[0065] As specifically shown in the illustrations according to Fig. 4 as well Fig. As can be seen in Figure 5, the press-fit nut 2 in the exemplary embodiment has a polygonal, and in particular hexagonal, cross-sectional contour. Both the head part 8 and the compression collar 20 have this polygonal structure. Correspondingly, the hole 28 and the embossed collar 38 also each have a corresponding polygonal structure.

[0066] When ring-shaped structures, such as annular gaps or ring-shaped compression collars, are mentioned, these are understood to be corresponding polygonal ring structures.

[0067] As an alternative to the polygonal structure, the compression collar 20, the head section 8, and also the hole 28 and the embossed band 38 can be circular. The polygonal structure achieves a particularly high level of resistance to twisting. Fig. Section 4 shows a section line A - A. The section views of the Fig. 1-3 as well as the Fig. Figure 6 each shows at least partial sections of cross-sectional areas along this section.

[0068] The special design of the press-fit nut 2 in the area of ​​the compression collar 20 will now be described using the Fig. 6 explained in detail: The base section 22 extends over a base height H1 starting from the horizontally running head support 16 to the axial height of the step 26.

[0069] In the exemplary embodiment, the step 26 runs horizontally and thus perpendicular to the central axis 10. Alternatively, it can also be inclined slightly outwards, in which case it forms an acute step angle with the horizontal plane, i.e., with a plane perpendicular to the pressing direction 12 or perpendicular to the central axis 10. This acute step angle lies between 1° and a maximum of 20°, and preferably between 3° and 8°. In the case of an inclined step 26, the axial height of the step 26 is defined by a mean axial height. The step 26 is generally formed by an annular surface.

[0070] The filling section 24, which extends over a filling height H2, is connected to this stage 26. In the exemplary embodiment, this is slightly less than the base height H1 and is, for example, 70%–90% of this base height H1. The two heights H1 and H2 together constitute the total height of the compression collar 20. This preferably corresponds to the thickness of the component 6 (sheet thickness). Alternatively, the total height of the compression collar is less than the thickness of the component 6.

[0071] The base section 22 has a base thickness D1 at the midpoint of the base height H1, i.e., at the mean base height H1. Correspondingly, the filling section 24 has a filling thickness D2 at the axial midpoint of the filling height H2, i.e., at the mean fill height H2, which is significantly less than the base thickness D1. For example, it lies only in the range between 10% and 30% of the base thickness D1.

[0072] Step 26 has a comparatively large radial step width B1. Radial step width B1 refers to the width of step 26 at its axial height. The compression collar 20 has a radial collar width B2 at this height. In this embodiment, the step width B1 is, for example, between 40% and 60% of the collar width B2.

[0073] The base section 22 and the filling section 24, and thus the compression collar 20 as a whole, together form an embodiment of the Fig. 6 outer circumferential side 48 running parallel to the central axis.

[0074] Alternatively, it is also possible that the entire circumference side 48 slopes diagonally inwards.

[0075] For example, the entire circumferential side 48 of the compression collar 20 is inclined inwards towards the central axis 10, or alternatively, only an outer side 50 of the filling section 24, or the filling section 24 as a whole. This serves to improve insertion into the gap between the perforated wall 30 and the embossing band 38 of the die during processing.

[0076] In the to Fig. 6 modified variants according to Fig. 8 is - based on the variant of Fig. 6 - the entire filling section 24 is inclined inwards. In the exemplary embodiment, this leads to the Fig. 8. The outer surface 50 of the filling section 24 is inclined obliquely inwards and thus towards the central axis. The inner surface of the filling section 24, and thus the lower inner section 54, is in the exemplary embodiment of the Fig. 8 is shown as an example, oriented parallel to the central axis. However, this is not mandatory.

[0077] According to one embodiment, an upper section of the circumferential side 48 in the area of ​​the base section 22 is parallel to the central axis 10 and a lower section of the circumferential side 48 in the area of ​​the filling section 24, which thus forms an outer side 50 of the filling section 24, is oriented obliquely inwards at an external angle of inclination with respect to a parallel to the central axis.

[0078] This outer surface 50 therefore forms a kind of insertion ramp. This outer angle of inclination is preferably in the range of 5° to a maximum of 30°. If the entire outer surface 50 is inclined, the outer angle of inclination is preferably in the range of 10–20%, and if only the filling section 24 is inclined, it is in the range of 10–30%.

[0079] In the exemplary embodiment, an inner surface of the compression collar 20 is inclined obliquely outwards. This inner surface is divided into an inner surface of the base section 22, which is designated as the upper inner section 52, and an inner surface of the filling section 24, which is designated as the lower inner section 54. These two sections 52 and 54 are inclined obliquely outwards at an upper angle of inclination α1 and a lower angle of inclination α2, respectively, with respect to the central axis 10. These angles of inclination α1 and α2 are preferably in the range between 10° and 40°. The two angles of inclination α1 and α2 are, for example, identical or preferably differ from each other by a maximum of + / - 20° or a maximum of 5°.

[0080] In the alternative embodiment, in which the outer surface 50 is inclined obliquely inwards in the manner of an insertion ramp, the lower inclination angle α2 is less than the upper inclination angle α1 by the outer inclination angle (preferably + / - max. 40° or max. 5°).

[0081] Sections 52 and 54 merge seamlessly at level 26. The transitions are preferably rounded.

[0082] Contrary to the direction of insertion 12, a slightly steeper angled upper wall section 56 adjoins the upper inner section 52. This is part of an intermediate section between the upsetting collar 20 and the beginning of the internal thread 14.

[0083] The internal thread 14 is axially spaced from the upsetting collar 20. This axial distance is, for example, between 0.5 and 1.5 times the base height H1. This measure ensures that the thread 14 is not deformed during the forming process. This reliably guarantees the dimensional accuracy of the thread 14 after pressing.

[0084] The press-fit connection 4 is preferably designed as follows: In a first step, the die 32 is inserted from below into the hole 28 until the component 6 comes to rest with its underside 36 on the ring shoulder 34. This situation is in the Fig. 1 and especially also in the Fig. Figure 7 shows the press-fit nut 2, which is still outside of hole 28.

[0085] The press-fit nut 2 is then offset in the press-fit direction 12, with the upsetting collar 20 leading into the hole 28 ( Fig. 2) and pressed against the die, specifically against the embossing plate 38, until the head support 16 comes to rest on the top surface 18 of the component 6 ( Fig. 3).

[0086] With the press-fit nut 2 described here, it is also possible in principle to first insert the press-fit nut 2 into the hole 28 with the compression collar 20 until the head support 16 comes to rest on the top 18 and only then to bring the die in from below and press it against the compression collar 20 to deform it.

[0087] However, the particular advantage of the press-fit nut 2 arises in the previously described procedure, in which the die 32 is first inserted into the hole 28.

[0088] In any case, the dimensions are chosen such that an annular clearance 58 (annular gap) is formed between the embossed collar 38, and in particular its circumferential side 44, and the hole wall 30. The radial outer dimension of the upsetting collar 20, and thus its circumferential side 48, is also dimensioned such that a clearance remains towards the hole wall 30. The gap dimension s of the clearance 58 between the circumferential side 44 of the embossed collar 38 and the hole wall 30 is preferably between 0.1 mm and 0.6 mm, or, particularly for larger dimensions (e.g., larger than M10), up to 1 mm. Preferably, the upsetting collar 20 has the same gap dimension to the hole wall 30 in its undeformed initial state, or alternatively, it is even slightly larger, e.g., by up to 20%.

[0089] In general, the filling section 24 has a radial outer dimension at its front end that is adapted to the radial outer dimension of the embossing collar 38 insofar as the filling section 24, with its front end, rests on the transition area 42 of the embossing collar 38. Subsequently, the annular surface 40 of the embossing collar 38 reaches the step 26 and preferably exerts only an axial force on it, so that the desired bulk forming occurs and material of the base section 22 is displaced radially outwards by flowing. Through this flow, the material is initially displaced in the radial direction and pressed against the hole wall 30.Subsequently, axial force components also act, so that the material of the filling section 24, which has meanwhile been immersed in the annular free space 58, also experiences an axial force component and is thus further pressed into the annular free space 58, fills it by material flow and is also pressed against the hole wall 30 in a radial direction.

[0090] The frontal arrangement of the comparatively thin filling section 24, which already dips into the annular free space 58 before the actual bulk forming, reliably ensures that the annular free space 58 is filled with material and, in particular, that pressure is applied against the hole wall 30 preferably over the entire length of the hole wall 30, even in the described process situation in which the embossing collar 38 is first inserted into the hole 28.

[0091] Overall, this results in a reliable and process-safe press-fit connection 4 with high pull-out resistance and good torsional rigidity. Furthermore, the press-fit connection 4 is generally watertight.

[0092] The perforated wall 30 is specially shaped by a punching operation such that it widens slightly towards the underside 36 and, in particular, is torn or broken out, forming a fracture surface 60. The underside 36 is also an underside in the punching process; that is, in this case, the punching tool is driven from above, from the top side 18, in the pressing direction 12 through the component 6 towards the underside 36. The fracture surface 60 is in the Fig. Figure 7 is exaggerated for illustration purposes. This fracture surface 60 is typically oriented at a fracture surface angle β to the central axis 10. The axial height typically extends over a maximum of 2 / 3 of the thickness of the component 6.

[0093] The material of the compression collar 20, and in particular of the filling section 24, is pressed into the radial widening of the hole 30 formed by the fracture surface 60. The axial pull-out protection is therefore decisively influenced and ensured by the specific design of the filling section 24.

[0094] The punching process described above often also deforms the perforated wall 30 in the area of ​​the top 18, so that the perforated wall 30 also has an indentation on the top 18.

[0095] In some applications, the requirement is that the hole punching process and the pressing in of the press-fit nut 2 are carried out from different directions, i.e. the punching process is carried out in the direction from the top 18 to the bottom 36, whereas the press-fit nut 2 is inserted from the bottom 36 of the component 6 in the direction of the top 18.

[0096] In this variant of the process, in which a punching operation and the pressing operation are carried out from opposite directions, the filling section 24 provides material compression against the (slightly) widened hole wall 30 in the area of ​​the top 18 and thus also achieves axial pull-out protection in this case. Reference symbol list 2 press-fit nuts 4 Press-fit connection 6 Component 8 Headboard 10 Central axis 12 Press-in direction 14 internal threads 16 Headrest 18 Top 20 compression collars 22 Basic section 24 Filling section Level 26 28 holes 30-hole pegboard 32 die 34 Ring shoulder 36 Underside 38 embossed bundle 40 ring area 42 Transition area 44 Circumference side of the embossed band 46 Ring collar 48 Circumference side of the compression collar 20 50 Outside of the filling section 52 upper inner section 54 lower inner section 56 upper wall section 58 ring-shaped free space 60 fracture surface H1 Base height H2 fill level D1 Base thickness D2 Filling thickness B1 radial step width B2 radial collar width α1 upper inclination angle of the upper inner section α2 lower inclination angle of the lower inner section β fracture surface angle s gap dimension QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2016 204 619 B4 [0002, 0004, 0015, 0017] DE 24 41 977 C2

[0005] DE 10 2012 220 033 A1

[0005] US 2007 / 0166128 A1

[0005]

Claims

[1] Press-in element (2), in particular press-in nut (2) for forming a press-in connection (4) with a pre-drilled component (6), wherein the press-in element (2) - extends in a press-in direction (12) along a central axis (10) - a head part (8) with a head support (16) for resting on the component (6) - has a compression collar (20) adjoining the head part (8) in the pressing direction (12), characterized by , that - the compression collar (20) has a base section (22) and a filling section (24), wherein the filling section (24) adjoins the base section (22) to form an internal step (26) oriented towards the central axis (10), wherein the base section (22) has an axial base height (H1) extending from the head support (16) to the step (26) and the filling section (24) has an axial filling height (H2) extending from the step (26) to a front end of the compression collar (20) in the press-in direction (12) [2] Press-in element (2) according to the preceding claim, characterized by that the filling height (H2) is in the range between 20% and 100% and in particular in the range between 30% and 60% of the base height (H1). [3] Press-in element (2) according to one of the preceding claims, characterized bythat the base section (22) has a base thickness (D1) at half the base height (H1) and the filling section (24) has a filling thickness (D2) at half the filling height (H2) and that the filling thickness (D2) is in the range between 5% and 40% and in particular in the range between 10% and 30% of the base thickness (D1). [4] Press-in element (2) according to one of the preceding claims, characterized by that the step (26) has a radial step width (B1) and the compression collar (20) has a radial collar width (B2) at the level of the step (26), and that the radial step width (B1) is in the range between 20% and 80% of the radial collar width (B2) and in particular in the range between 30% and 60% of the radial collar width (B2). [5] Press-in element (2) according to one of the preceding claims, characterized by that the base section (22) and the filling section (24) merge seamlessly into one another on the outside. [6] Press-in element (2) according to one of the preceding claims, characterized by that the base section (22) and the filling section (24) form a common circumferential side (48) which runs parallel to the central axis (10). [7] Press-in element (2) according to one of claims 1 to 5, characterized by that an outer side (50) of the filling section (24) is inclined obliquely inwards towards the central axis (10), preferably at an outer angle of inclination in the range between 5° and 30°. [8] Press-in element (2) according to one of the preceding claims, characterized by that an inner side of the filling section (24), referred to as the lower inner section (54), is inclined obliquely, preferably outwards, relative to the pressing direction (12) at a lower angle of inclination (α2), wherein the lower angle of inclination (α2) is in particular in the range between 10° and 40° and especially between 15° and 30°. [9] Press-in element (2) according to one of the preceding claims, characterized bythat an inner side of the base section (22), referred to as the upper inner section (52), is inclined obliquely outwards relative to the press-in direction (12) at an upper angle of inclination (α1), wherein the upper angle of inclination (α1) is in particular in the range between 10° and 40° and especially between 15° and 30°. [10] Press-in element (2) according to the preceding claim, characterized by that the upper inner section (52) is adjoined by an upper wall section (56) opposite to the pressing direction (12), which wall section is steeper than the upper inner section (52) and preferably extends to a cylindrical shape. [11] Press-in element (2) according to one of the preceding claims, characterized by that the compression collar (20) has a polygonal, in particular hexagonal outer contour (48). [12] Method for producing a press-in connection (4) between a press-in element (2) according to one of the preceding claims and a pre-punched component (6) with a hole (28) which has a circumferential hole wall (30), wherein the press-in element (2) dips into the hole (28) with its compression collar (20) and wherein the compression collar (20) is deformed with the aid of a die (32) which has a front embossed collar (38) so that collar material is pressed against the hole wall (30), in particular without an underside (36) of the component (6) being engaged behind by the compression collar (20). [13] Method according to the preceding claim, wherein the filling section (24) penetrates into an annular free space (58) between a peripheral side (44) of the front embossed collar (38) and the hole wall (30). [14] Method according to one of the two preceding claims, wherein firstly the component (6) is placed on the die (32) and the front embossed collar (38) dips into the hole (28), and then the press-in element (2) is pressed from above against the die (32). [15] Method according to one of claims 12 to 14, wherein the front embossed collar (38) has a radially extending end face (40) which is pressed against the step (26). [16] Method according to the preceding claim, wherein the end face (40) merges into a peripheral side (44) of the front embossed collar (38) via a rounded or chamfered transition region (42) and preferably an annular free space (58) exists between the peripheral side (44) and the hole wall (30) at the beginning of the pressing-in process. [17] Method according to one of the two preceding claims, wherein the end face (40) acts on the step (26) opposite to the pressing direction (12) and presses the collar material into a circumferential annular free space (58) between the front embossed collar (38) and the hole wall (30) by means of a solid forming process. [18] Method according to one of claims 15 to 17, wherein the end face is designed as an annular surface (40) which is delimited inwards towards the central axis (10) by an annular collar (46) which prevents displacement of collar material inwards towards the central axis (10). [19] Press-in connection (4) with a press-in element (2) according to one of claims 1 to 12, in particular produced by a method according to one of claims 13 to 18.

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