Connecting element and die

Abstract

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 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.

Description

[0001] 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.

[0002] 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.

[0003] 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.

[0004] 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.

[0005] According to the invention, a connecting element, in particular a flow-drilling screw, is provided with a head, a substantially cylindrical shaft, and a plate-like element, in particular a sealing washer, wherein the plate-like element has a through-opening through which the shaft 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 shaft.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.

[0006] 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.

[0007] 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.

[0008] In a further development of the invention, a ring-shaped indentation is provided which completely surrounds the through-opening of the plate-like element.

[0009] 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.

[0010] 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.

[0011] In this way, completely undeformed areas of the plate-like element can be ensured between the indentations, resulting in an improved sealing effect.

[0012] In a further development of the invention, the multiple indentations and projections are distributed evenly or unevenly around the circumference of the shaft.

[0013] Depending on the spatial conditions, a uniform or uneven distribution of the indentations and protrusions around the circumference of the shaft can be advantageous.

[0014] In a further development of the invention, an even or odd number of indentations and projections are provided.

[0015] In a further development of the invention, several indentations and projections are provided, wherein the indentations each have the form of a circular segment.

[0016] In a further development of the invention, the 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 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 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, a top 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 top 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 securing 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 several embossing elements are distributed evenly or unevenly around the circumference of the recess of the die.

[0029] Depending on spatial requirements, the embossing elements, and thus also the indentations on the underside of the plate-like element, can be distributed evenly or unevenly.

[0030] In a further development of the invention, an even or odd number of embossing elements of the die is provided.

[0031] 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.

[0032] In a further development of the invention, the embossing elements are designed to be circular, semicircular, square, rectangular, triangular and / or segment-shaped.

[0033] 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.

[0034] 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: Fig. 1 a partially cut-away side view of a connecting element according to a first embodiment of the invention, Fig. 2 a top view of a plate-like element of the screw of the Fig. 1, Fig. 3 a schematic sectional view of the plate-like element of the Fig. 2, Fig. 4 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, Fig. Figure 5 schematically and exemplarily shows four different designs of embossing elements on a die according to the invention. Fig. Figure 6 schematically shows five possible arrangements of embossing elements on a die according to the invention. Fig. Figure 7 shows a section view from an oblique top and a schematic partial sectional view of a die according to a further embodiment of the invention. Fig. Figure 8 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. Fig. Figure 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 the Fig. 10 to 12 three successive deformation steps when imprinting indentations into a plate-like element.

[0035] Fig. Figure 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.

[0036] The sealing washer 20 is captive secured to the shaft 14. This is achieved by providing the underside of the sealing washer 20 with radially inwardly extending projections or a circumferential, radially inwardly extending projection in the areas designated 22. 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. Fig. 1. The sealing disc 20 cannot be moved upwards beyond the underside of the head 12. In Fig. 1. The sealing washer 20 cannot be moved downwards over the thread 16.

[0037] 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.

[0038] Fig. Figure 2 shows a top view of the sealing disc 20 of the Fig. 2. The screw with head 12 and shaft 14 was omitted. The sealing washer 20 is in the state of Fig. 1. Formally secured to the shaft 14, so that it cannot be removed from the shaft 14 without damage. The sealing washer 20 in the Fig. The form shown in 2 can therefore only be detached from the shaft 14, for example, by cutting through the shaft 14 below the sealing washer 20, which then frees the sealing washer 20.

[0039] The sealing disc 20 has a central through-opening 24. In the deformed state of the Fig. 1 and Fig. 2. The circumference of the passage opening 24 is no longer circular as in the undeformed state. Four evenly spaced projections 26 extend into the passage opening 24. On the in Fig. On the concealed underside of the sealing disc 20, an indentation is arranged in the area of ​​each of the projections 26. When the indentation is formed, the sealing disc 20 deforms in such a way that the projections 26, extending radially inwards into the through-opening 24, are formed.

[0040] A distance between two opposing projections 26 is smaller than an outer diameter of the thread 16, see Fig. 1, so that the sealing washer 20 is in the Fig. 1 and Fig. The deformed state shown in Figure 2 is positively locked to the shaft 14 of the connecting element 10.

[0041] An area radially outside the projections 26 or radially outside the in Fig. The two concealed indentations are not deformed. This allows the entire radially outside area of ​​the sealing washer 20 to provide an undiminished sealing effect between the underside of the head 12 and the top side of a [unclear] Fig. 1. Not shown. For example, the connecting element 10 of the Fig. 1. Can be used to fasten and seal a cover for a vehicle battery.

[0042] Fig. Figure 3 shows a cross-sectional view through the sealing disc 20 of the Fig. 2, wherein the cutting plane passes through two opposing projections 26. In the sectional view of the Fig. Figure 3 shows that an indentation 28 is provided radially within each of the projections 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.

[0043] Fig. Figure 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.

[0044] In the presentation of the Fig. 4 Two opposing embossing elements 36 can be seen on a top surface of the die 32, immediately adjacent to a recess 34 of the die, which is provided for receiving the shaft of the connecting element 30. The embossing elements 36 can, for example, be designed as projections extending from a top surface of the die, cf. Fig. 9. It is in Fig. 4. It can be seen that a top 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 top surface of the respective embossing element 36, where in Fig. 4 left embossing element 36 also clockwise, where in Fig. 4. Right embossing element 36 counterclockwise. 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 inserted by means of a 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.

[0045] Fig. Figure 5 schematically shows various possible configurations of the embossing elements 36 on the die 32 within the scope of the invention. Fig. As can be seen in Figure 5, the embossing elements 36 can be circular, semicircular, rectangular, square, or triangular in a top view. The embossing elements 36 can also be, see Figure 5. Fig. 9, have the shape of a radially inwardly tapering quadrilateral, or it may, see Fig. 7 and Fig. 8, only one ring-shaped, in particular circular, embossing element 36 is provided.

[0046] In the four depictions of the Fig. Figure 5 shows only a single embossing element 36. According to the invention, an even or odd number of embossing elements 36 can be spaced evenly or unevenly apart to achieve the desired result. Fig. 5 each schematically indicated recess 34 of the matrix 32 are arranged around it.

[0047] Fig. Figure 6 schematically shows five different ways of arranging embossing elements 36 around the recess 34 of the die. Two embossing elements 36 can be provided opposite each other. Three embossing elements 36 can be provided, each spaced 120° apart. Four embossing elements 36 can be provided, each spaced 90° apart.

[0048] Alternatively, three embossing elements 36, which are unevenly spaced apart from each other, can be arranged around the recess 34.

[0049] Alternatively, three embossing elements 36, each evenly spaced apart and each shaped like a circular segment, can be arranged around the recesses 34.

[0050] Fig. Figure 7 shows a section view from an oblique top onto a die 42 according to a further embodiment of the invention. Fig. Figure 7 also shows a schematic partial sectional view of the die 42. Fig. Figure 7 shows that the die 42 has a single, ring-shaped embossing element 36, which surrounds the recess 34 of the die in the form of a ring-shaped protrusion. The embossing element 36 extends to the edge of the recess 34 and consequently extends one wall of the recess 34.

[0051] The schematic sectional view of the Fig. Figure 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.

[0052] 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.

[0053] Fig. Figure 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.

[0054] The remaining features of the embossing element 36 have already been described based on the Fig. Section 7 is explained and therefore will not be repeated.

[0055] Fig. Figure 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. A total of 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. The embossing elements 36 are, as shown in the schematic partial sectional view of the Fig. As can be seen from Figure 9, the first section 44 is also inclined towards the central longitudinal axis 38, in other words, slopes downwards towards the central longitudinal axis 38 in the first section 44. In a second section 46, which extends radially outwards from the first section 44, the upper surface of the embossing elements 36 is arranged at a right angle to the central longitudinal axis 38.

[0056] The Fig. 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.

[0057] Fig. Figure 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.

[0058] In the state of 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-opening of the sealing disc 20. It is Fig. It can be seen from Figure 10 that the upper 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 the Fig. 10. This angle is measured counterclockwise. Consequently, the top surface of the embossing element 36 slopes towards the central longitudinal axis 38.

[0059] In the state of Fig. 11 is the distance between a top surface of the embossing element 36 and a bottom surface of the head 12 of the connecting element 70, as shown in the illustration. Fig. 10 smaller and the indentation in the underside of the sealing disc 20 is compared to the state of the Fig. 10 already more deeply formed. In this state, it is already apparent that the material of the sealing disc 20, which is located between the top of the embossing element 36 and the bottom of the head 12 of the connecting element 70, begins to flow radially inwards. Already in the state of Fig. 11. An edge of the through-opening of the sealing disc 20 lies radially within the edge 76 in the area of ​​the embossing element 36 in the state of Fig. 10. As a result, a radial projection forms on the sealing disc 20 within the embossing element 36, which then extends into the through-opening of the sealing disc 20.

[0060] Fig. 12 shows one of the state of the Fig. 11 following state in which a distance exists between the underside of the head 12 of the connecting element 70 and an upper side of the embossing element 36 of the die 72 compared to the state of Fig. 11 is even smaller. The indentation in the underside of the sealing disc 20 is therefore even deeper and has, in the state of Fig. 12 the final depth is reached. The projection on the sealing disc 20, which extends radially inwards from the area of ​​the indentation, is in the state of Fig. 12 on an outer circumference of the shaft 14 of the connecting element 70. As a result of the impression being made, a projection 26 was 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 the Fig. Although the last thread 74 on the shaft 14 is no longer shown in figure 12, a comparison of the Fig. 12 and Fig. However, it can easily be seen 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.

[0061] At the same time, the Fig.Figures 10 to 12 show that the deformation of the sealing disc 20 occurs only 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, has not been deformed or has only been 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

[1] Fastening 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 seal against the top of a workpiece and to seal against the underside of the head, wherein the plate-like element is captive on the shank, characterized by, that the plate-like element is provided with at least one indentation in the area of ​​an edge of the through-opening, wherein the indentation extends from an underside of the plate-like element, which faces the free end of the shaft, towards an upper side of the plate-like element, which faces the underside of the head, and wherein, starting from the indentation, a projection, which has formed during the indentation, extends towards the shaft. [2] Connecting element according to claim 1, characterized by , that the at least one indentation has a base surface which, at least in sections, forms an angle of less than 90 degrees of the shaft with a central longitudinal axis of the through-opening of the plate-like element and which is inclined in the direction towards the shaft. [3] Connecting element according to claim 1 or 2, characterized by, that a ring-shaped indentation is provided which completely surrounds the through-opening of the plate-like element. [4] Connecting element according to any of the preceding claims, characterized by , that several spaced-apart indentations are provided, with a projection extending towards the shaft in the area of ​​each indentation. [5] Connecting element according to claim 4, characterized by that the multiple indentations and protrusions are evenly distributed around the circumference of the shaft. [6] Connecting element according to claim 4, characterized by that the multiple indentations and protrusions are unevenly distributed around the circumference of the shaft. [7] Connecting element according to any one of the preceding claims, characterized by that an even or odd number of indentations and projections are provided. [8] Connecting element according to any of the preceding claims, characterized bythat several indentations and protrusions are provided, each indentation having the form of a circular segment. [9] Connecting element according to any of the preceding claims, characterized by , that at least one impression 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 by, 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 embossing an indentation into a bottom surface 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 by , 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 in sections, so that the top surface of the at least one embossing element is inclined at least in sections in the direction of the central longitudinal axis. [12] Die according to claim 11, characterized by, that a first section of the top 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 by , that a second section of the top of the embossing element, which connects radially to the first section of the top, is arranged at an angle of 90 degrees to the central longitudinal axis of the die. [14] Die according to claim 13, characterized by , that the second section of the top surface is smaller in area than the first section of the top surface. [15] Die according to any one of claims 10 to 14, characterized by , that the embossing element of the die is ring-shaped and completely surrounds the recess in the die. [16] Die according to any one of claims 10 to 14, characterized by that several spaced-apart embossing elements of the die are provided. [17] Die according to claim 16, characterized by that the multiple embossing elements are evenly distributed around the circumference of the die recess. [18] Die according to claim 16, characterized by , that the multiple embossing elements are unevenly distributed around the circumference of the die recess. [19] Die according to at least one of claims 10 to 18, characterized by that an even or odd number of embossing elements are provided for the die. [20] Die according to at least one of claims 10 to 19, characterized by that several embossing elements of the die are provided, each of which has the form of a circular segment. [21] Arrangement according to at least one of claims 10 to 20, characterized by that the embossing elements are circular, semicircular, square, rectangular, triangular and / or segment-shaped.

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