Connecting element and die
The connecting element with a sealing washer and indentations ensures minimal deformation for captive attachment, maintaining sealing effectiveness, addressing the issue of impaired sealing due to deformation in existing technologies.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ARNOLD UMFORMTECHN
- Filing Date
- 2025-12-19
- Publication Date
- 2026-07-09
AI Technical Summary
Existing sealing washers on screws require significant deformation for captive attachment, which impairs their sealing effectiveness, especially under high pressures or with low-viscosity liquids, such as in battery housing applications.
A connecting element with a plate-like element, like a sealing washer, features indentations and projections that allow captive attachment without significant deformation, ensuring the washer remains undeformed in critical areas for sealing, using a die with embossing elements to create these features.
The solution provides a reliable, gas-tight and liquid-tight fastening mechanism by maintaining the sealing effectiveness of the washer through minimal deformation, enhancing its sealing performance under challenging conditions.
Smart Images
Figure EP2025088363_09072026_PF_FP_ABST
Abstract
Description
[0001] Connecting element and matrix
[0002] The invention relates to a connecting element, in particular a flow-drilling screw, comprising a head and a substantially cylindrical shank and a plate-like element, in particular a sealing washer, with a through-opening through which the shank extends, wherein the plate-like element is designed to seal against the top of a workpiece and against the underside of the head, and wherein the plate-like element is captive on the shank. The invention also relates to a die for an arrangement with a press punch.
[0003] Fasteners, such as screws, with sealing washers (i.e., washers with a sealing function) are well-known. Such sealing washers can also be captive attached to the screw shank. However, this usually requires a relatively significant deformation of the sealing washer, and this pre-deformation impairs the sealing effect. This is problematic when a seal against high pressures or low-viscosity liquids is required, particularly in the sealing of battery housings.
[0004] The invention aims to create a connecting element and a die for an arrangement with a press punch, in which a plate-like element is captively attached to the shaft of the connecting element or with which a plate-like element can be captively attached to the shaft of a connecting element, whereby a sealing function of the plate-like element should be impaired as little as possible.
[0005] According to the invention, a connecting element with the features of claim 1 or a die with the features of claim 10 is provided for this purpose. Further features and advantages of the invention are specified in the respective dependent claims.
[0006] According to the invention, a connecting element, in particular a flow-drilling screw, is provided with a head, a substantially cylindrical shank, and a plate-like element, in particular a sealing washer, wherein the plate-like element has a through-opening through which the shank extends. The plate-like element, in particular the sealing washer in the form of a washer, is designed to seal against the top surface of a workpiece and against the underside of the head. The plate-like element is captive and attached to the shank.The plate-like element is provided with at least one indentation in the region of an edge of the through-opening, wherein the indentation extends from an underside of the plate-like element facing the free end of the shaft towards an upper side of the plate-like element facing the underside of the head, and wherein a projection, formed during the indentation process, extends from the indentation towards the shaft. According to the invention, an indentation made from the underside of the plate-like element causes the material of the plate-like element to flow radially inwards into the through-opening of the plate-like element.Deformation of the plate-like element, which is made of a deformable, particularly ductile, material such as aluminum, occurs only in an area extending radially inward from the outermost end of the indentation. A region of the plate-like element located radially outside the indentation, however, remains undeformed and can fully contribute to the sealing effect of the plate-like element. For example, the connecting element is designed as a screw with a thread on the shank, particularly as a flow-drilling screw. Between the end of the thread and the underside of the head, screws with threads typically have a short shank section without a thread, where the outer diameter of the shank is smaller than the outer diameter of the thread.The protrusions that form when the indentation is pressed into the underside of the plate-like element can, for example, extend towards the unthreaded section of the shaft. These protrusions extend far enough towards the shaft to secure the plate-like element to the screw shaft in a form-fitting manner, as the plate-like element cannot be moved towards the underside of the head, nor can it be moved over the threads on the shaft. This fastener can be used, for example, for the gas-tight and liquid-tight fastening of a battery cover for a vehicle's traction battery.
[0007] In a further development of the invention, the at least one indentation has a base surface which, at least sectionally, forms an angle of less than 90° with a central longitudinal axis of the through-opening of the plate-like element and which is inclined in the direction towards the shaft.
[0008] The base surface is pressed into the plate-like element and forms the bottom of the indentation. By arranging the base surface at least partially obliquely to the central longitudinal axis and inclined towards the shaft, the material flow of the plate-like element, which lies between the underside of the connecting element head and the top of an embossing element on the die during the indentation process, is deformed radially inwards, i.e., into the through-opening of the plate-like element. Areas of the plate-like element lying radially outside the indentation are not deformed, or only to a negligible extent, so that they can contribute fully to the sealing effect of the plate-like element.
[0009] In a further development of the invention, a ring-shaped indentation is provided which completely surrounds the through-opening of the plate-like element.
[0010] A reliable, positive-locking connection of the plate-like element to the shank of the connecting element can be achieved by means of a ring-shaped indentation. Since the projection, which extends radially inwards from the indentation into the through-opening of the plate-like element, surrounds the shank by 360°, only a small degree of deformation or a small radial inward extension of the projection is required during the indentation process to reliably secure the plate-like element to the shank of the connecting element.
[0011] In a further development of the invention, several spaced-apart indentations are provided, wherein in the area of each indentation a projection extends towards the shaft.
[0012] In this way, completely undeformed areas of the plate-like element can be ensured between the indentations, resulting in an improved sealing effect.
[0013] In a further development of the invention, the multiple indentations and projections are distributed evenly or unevenly around the circumference of the shaft.
[0014] Depending on the spatial conditions, a uniform or uneven distribution of the indentations and protrusions around the circumference of the shaft can be advantageous.
[0015] In a further development of the invention, an even or odd number of indentations and projections are provided.
[0016] In a further development of the invention, several indentations and projections are provided, wherein the indentations each have the shape of a segment of a circular ring. In a further development of the invention, at least one indentation is circular, semicircular, square, rectangular, triangular and / or segment-shaped.
[0017] The problem underlying the invention is also solved by a die for an arrangement with a press punch, wherein the die is provided for imprinting at least one indentation into a plate-like element, wherein the plate-like element is provided on a connecting element, wherein the connecting element has a shaft and a head, and wherein the shaft extends through a through-opening of the plate-like element, and wherein the plate-like element is provided to abut sealingly against the top of a workpiece and sealingly against the underside of the head, wherein the die has a recess for receiving the shaft of the connecting element and at least one embossing element projecting from the die towards the press punch for imprinting an indentation into a bottom side of the plate-like element.wherein the embossing element is arranged adjacent to an edge of the recess or at a very small distance of less than 1 mm from the edge of the recess.
[0018] Using such a die according to the invention, an indentation can be created in the underside of a plate-like element, and a projection extending radially inwards from the indentation into a through-opening of the plate-like element can be produced. Deformation of the plate-like element occurs only in the area of the indentation and in the area of the projection, i.e., radially within the indentation. Areas of the plate-like element located radially outside the indentation, on the other hand, are not deformed and can therefore contribute fully to the sealing effect of the plate-like element.
[0019] In a further development of the invention, an upper surface of the at least one embossing element of the die facing the press punch forms an angle of less than 90° with a central longitudinal axis of the die at least partially, so that the upper surface of the at least one embossing element is inclined at least partially in the direction of the central longitudinal axis.
[0020] Consequently, at least part of the upper surface of the embossing element is always inclined such that the inclined section slopes towards the central longitudinal axis of the recess in the die. When an indentation is formed with the embossing element, material from the plate-like element located above the upper surface of the embossing element is displaced, among other things, radially inwards, i.e., towards the central longitudinal axis of the recess in the die. This creates radial projections within the indentation, which extend radially inwards and thus towards the shaft of a connecting element that is inserted through the opening in the plate-like element. The arrangement and design of the upper surface of the embossing element determines the arrangement and design of a base surface for the indentation during the embossing process.
[0021] In a further development of the invention, a first section of the upper surface of the embossing element adjacent to the recess of the die forms an angle of less than 90° with the central longitudinal axis of the die.
[0022] For example, the first section, which in other words slopes towards the central longitudinal axis of the die, can form an angle of 80° to 89°, for example 85°, with the central longitudinal axis. The essential point is that the angle is suitable for creating a radially inwardly extending projection of the plate-like element during the stamping process, which then results in a positive-locking, captive connection of the plate-like element to the connecting element.
[0023] In a further development of the invention, a second section of the top of the embossing element, which adjoins the first section of the top in a radial direction, is arranged at an angle of 90° to the central longitudinal axis of the die.
[0024] In this way, for example, it can be avoided to imprint sharp edges on the underside of the plate-like element, which could then in turn cause a local weakening of the plate-like element.
[0025] In a further development of the invention, the second section of the top surface is smaller in area than the first section of the top surface.
[0026] In a further development of the invention, the embossing element of the die is ring-shaped, in particular annular, and completely surrounds the recess in the die.
[0027] In a further development of the invention, several spaced-apart embossing elements of the die are provided.
[0028] In a further development of the invention, the multiple embossing elements are distributed evenly or unevenly around the circumference of the recess in the die. Depending on the spatial requirements, the embossing elements, and thus also the indentations on the underside of the plate-like element, can be distributed evenly or unevenly.
[0029] In a further development of the invention, an even or odd number of embossing elements of the die is provided.
[0030] In a further development of the invention, several embossing elements of the die are provided, each of the embossing elements having the form of a circular segment.
[0031] In a further development of the invention, the embossing elements are designed to be circular, semicircular, square, rectangular, triangular and / or segment-shaped.
[0032] Depending on the material and ductility of the plate-like element and the nature of the connecting element, the shape of the embossing elements can be chosen to create a projection of sufficient length radially within the indentations in the plate-like element, which then secures the plate-like element to the connecting element in a form-fitting manner.
[0033] 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 illustrated and / or described embodiments of the invention can be combined with one another in any way without exceeding the scope of the invention. This also applies to the combination of individual features without other individual features with which they are illustrated and / or described. The drawings show:
[0034] Fig. 1 shows a partially cut-away side view of a connecting element according to a first embodiment of the invention,
[0035] Fig. 2 shows a top view of a plate-like element of the screw of Fig. 1,
[0036] Fig. 3 is a schematic sectional view of the plate-like element of Fig. 2, Fig. 4 is a schematic sectional view of an arrangement with a connecting element according to the invention and a die according to a further embodiment of the invention,
[0037] Fig. 5 schematically and exemplarily shows four different designs of embossing elements on a die according to the invention,
[0038] Fig. 6 schematically shows five possible arrangements of embossing elements on a die according to the invention,
[0039] Fig. 7 shows a section view from an oblique top and a schematic partial sectional view of a die according to a further embodiment according to the invention.
[0040] Fig. 8 shows a section view from an oblique top view and a schematic partial sectional view of a die according to a further embodiment according to the invention.
[0041] Fig. 9 shows a section view from a top oblique angle and a schematic partial sectional view of a die according to a further embodiment of the invention, and
[0042] Figures 10 to 12 show three successive deformation steps in the imprinting of indentations into a plate-like element.
[0043] Fig. 1 shows a connecting element 10 according to a first embodiment of the invention in a partial sectional view. The connecting element 10 is designed as a screw with a head 12 and a shank 14. The shank 14 is essentially cylindrical and is provided with a thread 16 in sections. The head 12 is provided with a drive element 18 in the form of an internal polygon or an internal hexagon. The drive element 18 is located in the sectioned area of the connecting element 10. The sectioned area of the connecting element 10 also includes the last thread of the thread 16 below the underside of the head 12. A plate-like element in the form of a sealing washer 20 rests against the underside of the head 12. The sealing washer 20 has the shape of a washer and has a central through-hole. The sealing washer 20 is made of a ductile material, for example, aluminum.
[0044] The sealing washer 20 is captive secured to the shaft 14. This is achieved by providing an underside of the sealing washer 20 in the areas designated 22 with radially inwardly extending projections or a circumferential, radially inwardly extending projection. The projections or the projection engage a region of the shaft 14 that lies above the last thread of the thread 16 and the underside of the head 12. According to the invention, the projections or the projection need not extend to the shaft, as long as the sealing washer 20 is positively locked to the shaft 14. Since the outer diameter of the thread 16 is larger than the outer diameter of the region of the shaft 14 between the last thread of the thread 16 and the underside of the head 12, the sealing washer 20 is captive secured to the connecting element 12. This is shown in Fig.In Fig. 1, the sealing washer 20 cannot be moved upwards beyond the underside of the head 12. In Fig. 1, the sealing washer 20 cannot be moved downwards beyond the thread 16.
[0045] In the areas 22, an indentation or several indentations have been made in the underside of the sealing washer 20, with a projection or projections extending radially inwards from the indentation or indentations. As described, the sealing washer 20 is then positively secured to the shaft 14 of the connecting element 10 by means of the projection or projections.
[0046] Fig. 2 shows a top view of the sealing washer 20 of Fig. 2. The screw with the head 12 and the shaft 14 has been omitted. In the state shown in Fig. 1, the sealing washer 20 is positively locked to the shaft 14, so that it cannot be removed from the shaft 14 without damage. The sealing washer 20 in the form shown in Fig. 2 can therefore only be removed from the shaft 14, for example, by cutting the shaft 14 below the sealing washer 20, thus freeing the sealing washer 20.
[0047] The sealing disc 20 has a central through-opening 24. In the deformed state shown in Fig.
[0048] In Figures 1 and 2, the circumference of the through-opening 24 is no longer circular as in its undeformed state. Four evenly spaced projections 26 extend into the through-opening 24. On the underside of the sealing disc 20, which is hidden in Figure 2, an indentation is arranged in the area of each of the projections 26. When the indentation is formed, the sealing disc 20 deforms so that the projections 26, which extend radially inwards into the through-opening 24, are formed.
[0049] The distance between two opposing projections 26 is smaller than the outer diameter of the thread 16 (see Fig. 1), so that the sealing washer 20 is positively locked to the shank 14 of the connecting element 10 in the deformed state shown in Figs. 1 and 2. An area radially outside the projections 26, or radially outside the indentations hidden in Fig. 2, is not deformed. This allows the entire radially outside-the-indentation area of the sealing washer 20 to contribute fully to a sealing effect between the underside of the head 12 and the top of a workpiece not shown in Fig. 1. For example, the connecting element 10 of Fig. 1 can be used to fasten and seal a cover for a vehicle battery.
[0050] Fig. 3 shows a sectional view through the sealing disc 20 of Fig. 2, with the section plane passing through two opposing projections 26. The sectional view in Fig. 3 shows that an indentation 28 is provided radially within each projection 26 on the underside of the sealing disc 20. As will be explained below, the indentation 28 on the underside of the sealing disc 20 causes the material above an embossing element, with which the indentation 28 is produced, to be displaced radially inwards into the through-opening 24 of the sealing disc 20, thereby forming a projection 26 in the area of each indentation 28. Within the scope of the invention, the number, arrangement, and design of the indentations 28 can be varied, as long as the sealing disc 20 is positively secured to the shaft 14 after the indentations 28 have been made.
[0051] Fig. 4 shows an arrangement with a connecting element 30 according to a further embodiment of the invention and a die 32. The connecting element 30 is provided with a threaded shank, the free end of which is rounded. The connecting element 30 can be designed as a flow-drilling screw. Flow-drilling screws are placed onto a workpiece, for example, an unperforated battery cover. The connecting element is then rotated and pressed into place. Friction between the free end of the flow-drilling screw and the workpiece heats the workpiece sufficiently to create a through-hole and a passage through the workpiece.The thread on the shaft can then engage in the passage and the connecting element 30 can then be tightened until an underside of the sealing washer 40 seals against a top side of the workpiece and seals against an underside of the head 12 of the connecting element 30.
[0052] In the illustration of Fig. 4, two opposing embossing elements 36 can be seen on an upper surface of the die 32, immediately adjacent to a recess 34 of the die, which is provided for receiving the shank of the connecting element 30. The embossing elements 36 can, for example, be designed as projections extending from an upper surface of the die, cf. Fig. 9. It can be seen in Fig. 4 that an upper surface of the embossing elements 36 forms an angle of less than 90° with a central longitudinal axis 38 of the die. This angle is measured upwards from the upper surface of the respective embossing element 36, i.e., clockwise for the left embossing element 36 in Fig. 4 and counterclockwise for the right embossing element 36 in Fig. 4. The upper surfaces of the embossing elements 36 are thus inclined towards the central longitudinal axis 38 of the die 32. If the sealing disc is installed using a method shown in Fig.As the press ram, symbolized schematically by an arrow F, moves towards the die 32, the embossing elements 36 are pressed into an underside of the sealing disc 20. Due to the inclined arrangement of the upper surfaces of the embossing elements 36, the material of the sealing disc 20 located between the underside of the head 12 and the upper surface of the embossing elements 36 is displaced radially inwards. This creates radially inward-extending projections 26 of the sealing disc 20 within each indentation, or radially inward-extending projection 26, which extend radially inwards into the through-opening of the sealing disc 20 and towards the shaft of the connecting element 30. These projections 26 then allow the sealing disc 20 to be positively locked to the shaft of the connecting element 30.
[0053] Fig. 5 schematically shows various possible configurations of the embossing elements 36 on the die 32 within the scope of the invention. As can be seen in Fig. 5, the embossing elements 36 can be circular, semicircular, rectangular, square, or triangular in a top view. The embossing elements 36 can also, as shown in Fig. 9, have the shape of a radially tapering quadrilateral, or, as shown in Figs. 7 and 8, only an annular, in particular circular, embossing element 36 can be provided.
[0054] In the four illustrations of Fig. 5, only a single embossing element 36 is shown in each. According to the invention, an even or odd number of embossing elements 36 can be arranged at even or uneven intervals around the recess 34 of the die 32, which is schematically indicated in Fig. 5.
[0055] Fig. 6 schematically shows five different ways of arranging embossing elements 36 around the recess 34 of the die. Two opposing embossing elements 36 can be provided. Three embossing elements 36 spaced 120° apart can be provided. Four embossing elements 36 spaced evenly 90° apart can be provided.
[0056] Three embossing elements 36, which are unevenly spaced apart from each other, can also be arranged around the recess 34. Alternatively, three embossing elements 36, each shaped like an annular segment and spaced evenly apart from each other, can be arranged around the recesses 34.
[0057] Fig. 7 shows a section view from a top oblique angle of a die 42 according to a further embodiment of the invention. Fig. 7 also shows a schematic partial sectional view of the die 42. In Fig. 7, it can be seen that the die 42 has a single, annular embossing element 36, which surrounds the recess 34 of the die in the form of an annular protrusion. The embossing element 36 extends to the edge of the recess 34 and consequently extends one wall of the recess 34.
[0058] The schematic sectional view in Fig. 7 shows that a first section 44 of the upper surface of the embossing element 36 of the die 42 is inclined at an angle α to the central longitudinal axis 38, so that the first section 44 of the upper surface of the embossing element 36 slopes towards the central longitudinal axis 38. The first section 44 begins at the edge of the recess 34 of the die 42. A second section 46 of the upper surface of the embossing element 36 adjoins the first section 44 and extends to the radially outer end of the embossing element 36. This second section 46 of the upper surface of the embossing element 36 is arranged at an angle of 90° to the central longitudinal axis 38.
[0059] The embossing element 36 extends by a height H beyond an annular top surface of the die 42. For example, the height H is 0.5 mm.
[0060] Fig. 8 shows another die 52 according to the invention in a section view from an oblique top view and in a partial sectional view. An embossing element 36 in the die 52 is also ring-shaped and differs from the embossing element 36 of the die 42 only in its smaller height H, which is, for example, 0.2 mm.
[0061] The remaining features of the embossing element 36 have already been explained with reference to Fig. 7 and are therefore not repeated.
[0062] Fig. 9 shows a die 62 according to a further embodiment of the invention. The die 62 has a cylindrical recess 34 for receiving the shaft of a connecting element, see also Fig. 4. Three embossing elements 36, each rectangular in shape, adjoin the edge of the recess 34, with the width of the rectangular embossing elements 36 decreasing towards the central longitudinal axis 38 of the die 62. As can be seen from the schematic partial sectional view in Fig. 9, the embossing elements 36 are also inclined in a first section 44 towards the central longitudinal axis 38, in other words, sloped towards the central longitudinal axis 38 in the first section 44. In a second section 46, which extends radially outwards to the first section 44, the upper side of the embossing elements 36 is arranged at a right angle to the central longitudinal axis 38.
[0063] Figures 10 to 12 show sectional representations of a connecting element 70 and a die 72 according to the invention during three successive forming steps when introducing an indentation into a sealing disc 20 of the connecting element 70.
[0064] Fig. 10 shows another section of the uppermost thread 74 on the shank of the connecting element 70. It can be seen that between the underside of the head 12 of the connecting element and the first thread 74, a section of the shank 14 is formed which has a smaller outer diameter than the outer diameter of the thread 16 with the first thread 74.
[0065] In the state shown in Fig. 10, the sealing disc 20 rests with its upper surface against a lower surface of the head 12. An embossing element 36 of the die 72 rests against a lower surface of the sealing disc 20 and has already created a shallow indentation in the lower surface of the sealing disc 20. The indentation begins at the edge 76 of the through-hole of the sealing disc 20. Fig.
[0066] As can be seen from Figure 10, the top surface of the embossing element 36 forms an angle of less than 90° with the central longitudinal axis 38 of the die 72. In the illustration of Figure 10, this angle is measured counterclockwise. Consequently, the top surface of the embossing element 36 slopes towards the central longitudinal axis 38.
[0067] In the state shown in Fig. 11, the distance between the upper surface of the embossing element 36 and the lower surface of the head 12 of the connecting element 70 is smaller than in Fig. 10, and the indentation in the lower surface of the sealing washer 20 is already deeper than in Fig. 10. In this state, it is already apparent that the material of the sealing washer 20, located between the upper surface of the embossing element 36 and the lower surface of the head 12 of the connecting element 70, begins to flow radially inwards. Already in the state shown in Fig. 11, the edge of the through-opening of the sealing washer 20 in the area of the embossing element 36 lies radially inside the edge 76 in the state shown in Fig. 10. Consequently, a projection forms radially inside the embossing element 36 on the sealing washer 20, which then extends into the through-opening of the sealing washer 20. Fig. 12 shows a representation of the state shown in Fig. 11.Figure 11 shows the following state, in which the distance between the underside of the head 12 of the connecting element 70 and an upper surface of the embossing element 36 of the die 72 is even smaller than in the state of Figure 11. The indentation in the underside of the sealing washer 20 is therefore even deeper and has reached its final depth in the state of Figure 12. The projection on the sealing washer 20, which extends radially inwards from the area of the indentation, rests against an outer circumference of the shaft 14 of the connecting element 70 in the state of Figure 12. As a result of the indentation, a projection 26 has been formed on the sealing washer 20, which extends radially inwards and ensures a positive locking connection of the sealing washer 20 to the shaft 14 of the connecting element 70. In the illustration of Fig. 12, the last thread 74 on the shaft 14 is no longer shown, but it can be seen by comparing the Fig.However, it can easily be seen from figures 12 and 11 that the projection 26 reliably ensures that the sealing washer 20 can no longer be moved downwards along the shaft 14 beyond the first thread 74 of the thread 16.
[0068] At the same time, it can be seen from Figures 10 to 12 that the sealing disc 20 is only deformed in an area extending inwards from a radially outer end of the embossing element 36. Consequently, an area 78 of the sealing disc 20, which lies radially outside the embossing element 36 on the die 72, is not deformed or only deformed to a negligible extent. In this area, the sealing disc 20 can therefore still deform without difficulty to ensure a reliable seal against the top of a workpiece and the underside of the head 12 of the connecting element 70.
Claims
Patent claims 1. Connecting element, in particular a flow-drilling screw, with a head and a substantially cylindrical shank and a plate-like element, in particular a sealing washer, with a through-opening through which the shank extends, wherein the plate-like element is provided to abut sealingly against the top of a workpiece and sealingly against the underside of the head, wherein the plate-like element is captive on the shank, characterized in that the plate-like element is provided with at least one indentation in the region of an edge of the through-opening, wherein the indentation extends from an underside of the plate-like element facing the free end of the shank towards an upper side of the plate-like element facing the underside of the head, and wherein a projection, formed during the indentation process, extends from the indentation.extends towards the shaft.
2. Connecting element according to claim 1, characterized in that the at least one indentation has a base surface which, at least sectionally, forms an angle of less than 90 degrees with a central longitudinal axis of the through-opening of the plate-like element and which is inclined towards the shaft.
3. Connecting element according to claim 1 or 2, characterized in that an annular indentation is provided which completely surrounds the through-opening of the plate-like element.
4. Connecting element according to one of the preceding claims, characterized in that several spaced-apart indentations are provided, wherein in the area of each indentation a projection extends towards the shaft.
5. Connecting element according to claim 4, characterized in that the multiple indentations and projections are evenly distributed around the circumference of the shaft.
6. Connecting element according to claim 4, characterized in that the multiple indentations and projections are unevenly distributed around the circumference of the shaft.
7. Connecting element according to one of the preceding claims, characterized in that an even or odd number of indentations and projections are provided.
8. Connecting element according to one of the preceding claims, characterized in that several indentations and projections are provided, wherein the indentations each have the form of a circular segment.
9. Connecting element according to one of the preceding claims, characterized in that the at least one indentation is circular, semicircular, square, rectangular, triangular and / or segment-shaped.
10. Die for an arrangement with a press punch, wherein the die is provided for imprinting at least one indentation into a plate-like element, in particular a sealing disc, wherein the plate-like element is provided on a connecting element, wherein the connecting element has a shaft and a head, and wherein the shaft extends through a through-opening of the plate-like element, and wherein the plate-like element is provided to abut sealingly against the top of a workpiece and sealingly against the underside of the head, characterized in that the die has a recess for receiving the shaft of the connecting element and at least one embossing element projecting from the die towards the press punch for imprinting an indentation into an underside of the plate-like element.wherein the embossing element is arranged adjacent to an edge of the recess or at a very small distance of less than one millimeter from the edge of the recess.
11. Die according to claim 10, characterized in that a top surface of the at least one embossing element of the die facing the press punch forms an angle of less than 90 degrees with a central longitudinal axis of the die at least partially, so that the top surface of the at least one embossing element is inclined at least partially in the direction of the central longitudinal axis.
12. Die according to claim 11, characterized in that a first section of the upper surface of the embossing element adjacent to the recess of the die forms an angle of less than 90 degrees with the central longitudinal axis of the die.
13. Die according to claim 12, characterized in that a second section of the top of the embossing element, which adjoins the first section of the top in a radial direction, is arranged at an angle of 90 degrees to the central longitudinal axis of the die.
14. Die according to claim 13, characterized in that the second section of the top surface is smaller in area than the first section of the top surface.
15. Die according to one of claims 10 to 14, characterized in that the embossing element of the die is ring-shaped and completely surrounds the recess in the die.
16. Die according to one of claims 10 to 14, characterized in that several spaced-apart embossing elements of the die are provided.
17. Die according to claim 16, characterized in that the multiple embossing elements are evenly distributed around the circumference of the recess of the die.
18. Die according to claim 16, characterized in that the multiple embossing elements are unevenly distributed around the circumference of the recess of the die.
19. Die according to at least one of claims 10 to 18, characterized in that an even or odd number of embossing elements of the die is provided.
20. Die according to at least one of claims 10 to 19, characterized in that several embossing elements of the die are provided, each of the embossing elements having the form of a circular segment.
21. Arrangement according to at least one of claims 10 to 20, characterized in that the embossing elements are circular, semicircular, square, rectangular, triangular and / or segment-shaped.