Process

Abstract

The invention relates to a method for producing at least one part of a hydraulic accumulator, comprising at least the following method steps:-providing an accumulator housing part (20) having at least one fluid connection point (28),-providing a connection body (30) with a fluid passage (60), which connection body has a material stack (64) on one free end face thereof, and-providing a fluid passage (60) on the other free end face of the connection body (30). Placing the material deposit (64) on the energy accumulator housing part (20) in such a way that the fluid connection point (28) in the energy accumulator housing part (20) is fluidically connected to the fluid passage (60) of the connection body (30), melting the material deposit (64) by means of a welding method, joining the coupling body (30) and the energy storage housing part (20) together with a predeterminable pressing force and a predeterminable stroke, and cooling the resulting welded connection.

Description

Technical Field

[0001] The invention relates to a method for producing at least a part of a hydraulic accumulator and to a hydraulic accumulator produced in particular according to the method. Background Art

[0002] DE 10 2009 049 547 B3 discloses a method for producing a hydropneumatic pressure accumulator, which method comprises in particular the following method steps:

[0003] - providing a valve body with a projection at a face facing the valve seat,

[0004] - placing the valve body into an injection mold for forming the diaphragm forming the flexible, movable partition element, and

[0005] The elastomer forming the diaphragm is injected in such a way that the valve body is embedded in the elastomer with the surface facing the valve body being free.

[0006] In order to complete a hydropneumatic pressure accumulator, such an arrangement is introduced into the accumulator housing, wherein a housing opening is provided on the accumulator housing, forming an access to the fluid space, and a coupling body adjoins the housing opening in order to connect the accumulator to a conventional hydraulic system. For this purpose, the coupling body is fixedly connected to the accumulator housing by a circumferential fillet weld, with its fluid passage arranged coaxially with the housing opening in the accumulator housing.

[0007] A comparable hydraulic accumulator, in particular a hydraulic accumulator in the form of a diaphragm accumulator, is known from DE 10 2015 012 357 A1, which consists of at least two housing parts of an accumulator housing, in which a separating element in the form of a separating diaphragm separates two medium spaces from each other, and the hydraulic accumulator has at least one medium-connecting component connected to one housing part along a weld seam, which medium-connecting component is at least partially embedded in a receiving space as a coupling body for connecting the hydraulic accumulator to a hydraulic system, and the receiving space is formed in this housing part along a housing opening, wherein the walls of the housing and the coupling body that face each other adjacently in the receiving space are fixedly connected to each other by means of a weld seam.

[0008] In a comparable hydraulic accumulator structure according to DE102021000139A1, the accumulator housing has a fluid connection portion, which leads into an adjacent medium space of the housing and has a coupling body with a fluid through-portion, which is fixedly connected to the accumulator housing via a weld, wherein the coupling body has an annular outer circumference at its connection area facing the accumulator housing, and when the coupling body is placed on the accumulator housing at the end side, the annular outer circumference forms a transition portion, and the weld extends along the transition portion. Summary of the invention

[0009] Starting from this, the present invention is based on the object of further improving such prior art while maintaining the advantages of the prior art, namely achieving a secure connection between a coupling body for connecting a hydraulic accumulator to a fluid system, in particular a hydraulic system, and an accumulator housing of such a hydraulic accumulator in such a way that hydraulic accumulators with accumulator housing and coupling body can be manufactured in large numbers in a particularly cost-effective manner and with functional reliability.

[0010] This object is achieved by a method having all the features of claim 1 and by a hydraulic accumulator having the features of claim 5 , in particular a hydraulic accumulator produced using such a method.

[0011] The method according to the invention for producing at least a part of such a hydraulic accumulator is characterized by the following method steps:

[0012] - providing an accumulator housing part, which has at least one fluid connection point,

[0013] - providing a coupling body with a fluid passage, said coupling body having a material accumulation on one of its free ends,

[0014] - placing the material accumulation against the accumulator housing part in such a way that a fluid connection point in the accumulator housing part is fluidically connected to a fluid passage of the coupling body,

[0015] - melting the material accumulation by means of a welding method,

[0016] - joining the coupling body and the accumulator housing part together with a predeterminable contact pressure and a predeterminable stroke, and

[0017] - Allowing the resulting welded joint to cool.

[0018] By melting the material accumulation, which is preferably an integral component of the coupling body, the welding method can be carried out without additional welding material in such a way that a particularly uniform welded connection is produced between the accumulator housing part and the coupling body. Under high contact pressure when joining the coupling body and the accumulator housing part together, a very strong connection between the components is also produced, which can also reliably withstand greater stresses in subsequent actual operation.

[0019] Particularly preferably, resistance pressure welding, in particular resistance projection welding, is used as the welding method. The last-mentioned welding method is also referred to in the technical terminology as projection welding and is a variant of resistance pressure welding. The welded connection is produced by introducing current into the components to be connected to one another in the form of accumulator housing parts and associated connectors and by introducing a contact pressure that is applied to the workpieces to be connected to one another using large-area electrodes.

[0020] The material accumulation on the free end side of the coupling body acts as a projection, which can also be divided into individual joint parts. The energy input, i.e. the current density at the welding point, is then achieved through the material accumulation, which melts at this time. Therefore, during the actual welding process, the melted material accumulation is basically reshaped due to the electrode force and the heating heat generated by the current flow between the accumulator housing part and the coupling body, wherein this reshaping is usually not complete and the reshaped projection during welding regularly constructs a welded connection structure in the form of a flat nugget, which has a central through-hole for the fluid in the current special case. Therefore, the reshaped material accumulation can also be arranged in addition or alternatively before the welding process at the following accumulator housing part, which is opposite to the coupling body to be welded. However, for the projection welding itself, it is advantageous that the material accumulation is arranged at the coupling body, which can thus be placed in a particularly simple way by means of a pressing-anode against the accumulator housing part constructed as a cathode.

[0021] Separation elements in the form of separation membranes can then be inserted regularly into the accumulator housing part with the welded connection body by means of a holder, and then further accumulator housing parts in the form of spherical segments can be welded to the accumulator housing part to form a hydraulic accumulator, for which various welding methods can be used, in particular laser welding methods that can be handled without additional welding material. As a result, the internal structure of the accumulator housing of the hydraulic accumulator can be produced at one time at different production locations, while the pre-welded semi-finished product consisting of accumulator housing parts and welded connection bodies can be completed in a further welding method step after the separation elements are inserted by means of a holding device to form a total hydraulic accumulator, which can be closed on its other medium side, in particular the gas side, by means of a closure plug or a closure screw, which is inserted into a further fluid connection point of the accumulator housing. In this regard, there is also the possibility of fixing the aforementioned coupling body not only on the liquid side of the accumulator housing, but also on its gas side by means of projection welding with the provision of corresponding material deposits or projections, wherein the further coupling body on the gas side is then a closing body which, however, can be provided with a refilling device for the gas, for example.

[0022] The invention also relates to a hydraulic accumulator, which is manufactured, in particular, by means of a method according to any of the preceding claims, and which has an accumulator housing and a separating element arranged in the accumulator housing, which separates two media spaces from one another, wherein the accumulator housing has at least one fluid connection point, which opens into an adjacent media space, and the hydraulic accumulator has a coupling body with a fluid passage, which is fixedly connected to the accumulator housing by means of a welded connection structure in such a way that the fluid connection point of the accumulator housing is fluidically connected to the fluid passage of the coupling body, wherein the welded connection structure between the accumulator housing part and the coupling body is formed by a reshaped material accumulation of the coupling body, which material accumulation forms a weld nugget with a through-opening as part of the fluid connection. In particular, the above-mentioned material accumulation is part of the coupling body as a so-called projection before its reshaping. The electrical contact resistance and the material resistance or material resistance of the participating joint partners (here in the form of the accumulator housing part and the associated coupling body) essentially contribute to the formation of the weld nugget with the fluid passage. The contact resistance between the joint partners is essentially influenced by the projection geometry, the contact force generated by at least one of the electrodes and the surface conditions of the accumulator housing part and the connection body. The weld nugget itself is surrounded by a heat-affected zone, wherein the material structure of the respective joint partner is changed, in particular homogenized, in the heat-affected zone. The setting parameters for producing a suitable weld nugget are ultimately the welding current, the welding current time and the applied electrode force.

[0023] In a preferred embodiment of the hydraulic accumulator according to the invention, the material accumulation is formed by an annular projection, which surrounds the fluid passage at the coupling body and is an integral component of the coupling body. Preferably, the annular material accumulation is triangular in cross section and produces an opening angle at the top of the triangle that is between 70° and 110°, preferably between 80° and 100° and particularly preferably about 90°. It has been shown that the geometric triangular shape of the projection (especially also with regard to material thickness and material strength) is particularly suitable for ensuring good force introduction and for optimal reshaping of the material accumulation in the direction of the creation of the weld nugget between the mentioned joining partners.

[0024] It is also advantageous here if the material accumulation merges on the outer circumference and / or on the inner circumference into a boundary surface which is perpendicular to the longitudinal axis of the coupling body. Additional support occurs in the reshaping region via the corresponding boundary surface, resulting in an improved weld joint structure. As an alternative to this, it is also possible to merge the boundary surface on the outer circumference at a predeterminable angle into an inclined surface which is part of the one free end face of the coupling body. This also reliably supports the reshaping, so that the material accumulation or the projection cannot already undergo an impermissibly high reshaping before the actual welding process begins.

[0025] It is particularly preferred that the boundary surface transitions on the inner circumference in a vertical extension viewed parallel to the longitudinal axis of the coupling body into the threaded region of the coupling body, which significantly simplifies the coupling of the hydraulic accumulator as a whole to a fluid or hydraulic system via the associated screw connection.

[0026] Another advantage is that the weld seam / joint area can be inspected by means of non-destructive testing methods, such as ultrasound. The inner side of the half shell provides an ideal surface for irradiation. Porosity or bonding defects in the joint area can thus be detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The solution according to the invention is explained in more detail below with the aid of an embodiment according to the drawings. Here, a schematic and not to scale illustration is shown:

[0028] Figure 1 The important joining partners in the form of accumulator housing parts and coupling bodies for producing the welded connection are shown;

[0029] Figure 2 Shown according to Figure 1 A change in the coupling body;

[0030] Figure 3 and Figure 4 For the purpose of explaining the principle, the attachment of the coupling body to the accumulator housing or the produced welded connection between the accumulator housing and the coupling body using welding electrodes is shown from the outside; and

[0031] Figure 5 Show according to Figure 4 Schematic diagram of a longitudinal section through a hydraulic accumulator. DETAILED DESCRIPTION

[0032] exist Figure 5The hydraulic accumulator shown in longitudinal section in FIG. 1 is a so-called diaphragm accumulator with a separation element 12 in the form of a diaphragm made of an elastomeric material, which is arranged in an accumulator housing, which is indicated as a whole by 10. The diaphragm divides the housing 10 in its interior into a medium space 14 in the form of a fluid space for storing a liquid, in particular a liquid in the form of hydraulic oil, and a further medium space 16 in the form of a gas space for storing an operating gas, in particular an operating gas in the form of nitrogen.

[0033] In the DPRK Figure 5 The housing 10, viewed in the viewing direction, consists of an upper accumulator housing part 18 and a lower accumulator housing part 20, each of which has a circular shell shape or a spherical segment shape with a central axis 22, which corresponds to the longitudinal axis of the hydraulic accumulator. The upper accumulator housing part 18 has a flatter shell shape than the lower accumulator housing part 20. At the end of the accumulator housing 10 opposite the fluid space 14, i.e., at the end belonging to the gas space 16, the upper accumulator housing part 18 has an upper fluid connection 24 concentrically with the axis 22, which can be closed by means of a plug or by means of a solder 26 after the gas space 16 is filled. A lower fluid connection 26 is arranged concentrically with the axis 22 on the lower accumulator housing part 20, on which a lower coupling body 30 is arranged as an oil connection, by means of which the accumulator can be connected to a hydraulic system (not shown) in the usual way.

[0034] The upper accumulator housing part 18 and the lower accumulator housing part 20 have a central upper fluid channel 32 or a lower fluid channel 34, respectively, which extend centrally along the longitudinal axis 22 through the accumulator housing wall 36 of the upper accumulator housing part 18 and open into the gas space 16 or extend centrally from the lower fluid connection 28 through the accumulator housing wall 38 of the lower accumulator housing part 20 and open into the fluid space 14. The respective channels 32, 34 are components of the upper fluid connection 24 or the lower fluid connection 28. Starting from a constant outer diameter, the housing wall 36 of the upper accumulator housing part 18 extends away from the lower accumulator housing part 20 and toward the longitudinal axis 22 of the hydraulic accumulator, curving outwardly, as far as the central upper fluid channel 32. In contrast, starting from a constant outer diameter, the housing wall 38 of the lower accumulator housing part 20 initially extends away from the upper accumulator housing part 18 and in an outwardly curved manner toward the longitudinal axis 22 of the hydraulic accumulator and then transitions into a plate 40 that is flat on both sides and is disk-shaped, through which the lower fluid channel 34 extends centrally as the lower fluid connection point 28.

[0035] The upper accumulator housing part 18 and the lower accumulator housing part 20 (the upper accumulator housing part and the lower accumulator housing part abut along a weld seam 42) are connected to each other by means of a laser welding method or an electron beam welding method, and in order to protect the interior of the accumulator housing 10 from welding spatter and / or heat input during welding, the upper accumulator housing part 18 is provided with a downwardly protruding annular edge 44 on the inner circumference, which, as soon as the two housing parts 18, 20 are placed on each other, covers the weld seam 42 inwardly in a protective manner as an edge projection.

[0036] Below the annular edge 44 and adjacent to it, a support is provided, which is designated as a whole by 46 and has a fixing ring 48 with an annular receptacle 49 for receiving an edge bead 50 at the thickened circumference of the diaphragm-like separating element 12. Furthermore, the edge bead 50 is supported on the outer circumference in a groove-shaped receptacle 52 or recess in the inner wall of the lower accumulator housing wall 38, so that the receptacle 52 and the annular receptacle 49 in the fixing ring 48 together form a seat for the thickened edge bead 50. If the fixing ring 48 is formed as a metal sheet metal molded part, the edge bead 50 and thus the separating element 12 can be fixed to the lower accumulator housing wall 38 by the inherent elasticity of the fixing ring 48 with a preload force.

[0037] Furthermore, the separating element 12 has a solid valve body 54 as a separating membrane, which can cover an edge 56 of the inlet of the lower fluid connection 28, forming a kind of valve seat, if the valve body 54 rests against the aforementioned edge 56 in the lowest deflected position of the separating element 12. The coupling body 30 can be, for example, Figure 3 and Figure 4 As shown, it has a connection surface 58 for connecting an operating tool, for example in the form of a conventional hexagonal wrench, in order to improve the installation of the hydraulic accumulator on the hydraulic system. Figure 1 , Figure 2 and Figure 5 As shown, the coupling body 30 also has a fluid passage 60, which, if the coupling body 30 is fixedly connected to the accumulator housing 10, extends concentrically with the longitudinal axis 22 of the hydraulic accumulator. In particular, the free cross-section of the fluid passage 60 is designed to be larger than the channel diameter for the lower fluid connection part 28. Figure 1 and Figure 2 As shown in FIG. 1 , the fluid passage 60 is at least partially provided with a common internal thread as a threaded area 62, which enables the fluid passage 60 to be provided with a common internal thread as a threaded area 62. Figure 5The hydraulic accumulator can be screwed onto the coupling component of the hydraulic system. Such a coupling connection between the hydraulic accumulator and the hydraulic system is common, so it will not be discussed in more detail here. Figure 5 Starting from the common structure of hydraulic accumulators, from now on, according to Figures 1 to 4 The manufacturing method according to the invention is explained in more detail, wherein the components described and used so far are provided with Figure 5 The same reference numerals as in FIG. 1 and the explanations thereon also apply to Figures 1 to 4 Description of the method flow.

[0038] In the manufacturing method according to the present invention, the lower accumulator housing part 20 is first connected to the coupling body 30. Figure 1 . In this case, first of all, a lower accumulator housing part 20 is provided, which has a lower fluid connection point 28. In addition, a coupling body 30 is provided, which has its fluid passage 60 and has a material accumulation 64 on its free upper end side, which is also called a bump in the technical terminology. In a further method step, the material accumulation 64 of the coupling body 30 is then fixed to the lower accumulator housing part 20 in such a way that the fluid connection point 28 in the accumulator housing part 20 is fluidically connected to the fluid passage 60 of the coupling body 30, wherein both the fluid connection point 28 and the fluid passage 60 of the coupling body 30 are arranged concentrically with the longitudinal axis 22 of the hydraulic accumulator.

[0039] Subsequently, the material accumulation 64 is melted by means of a special welding method, which will be explained in more detail. However, the basic prerequisite for welding is that the coupling body 30 and the lower accumulator housing part 28 are joined together under a predeterminable pressing force, which is determined according to the Figure 3 The illustration is preferably applied by a vertically movable electrode in the form of an anode 66, which is Figure 3 The anode is only partially shown in FIG. 1 and transitions at its upper end or at its upper free end side into a flat contact surface 80 which can be flatly contacted with the underside of the connecting body 30 . Figure 3 and Figure 5 , the welded connection 70 produced in this respect can then be cooled, thereby creating a fixed connection between the accumulator housing part 20 and the coupling body 30 .

[0040] According to the invention, so-called resistance pressure welding, in particular resistance projection welding, is used as the welding method. In resistance projection welding, as already explained, the coupling body 30 is pressed against the accumulator housing part 18 as cathode 72 with a preset pressing force by means of the anode 66, and when a voltage or current is applied accordingly not only to the anode 66 but also to the cathode 72, when the coupling body 30 is placed against the lower side of the accumulator housing part 20, due to the resulting contact resistance, the material accumulation 60 melts and due to the pressing force caused by the anode 66, the material accumulation 64 is reshaped until an annular weld nugget 74 is obtained, which, after its cooling, establishes the actual welded connection structure 70 between the accumulator housing part 20 and the coupling body 30. In this case, the weld nugget 74 has a through-opening 76 in the form of a circular ring, which, in the case of optimal welding, corresponds to the inner diameter of the fluid passage 60 of the coupling body 30, which is in particular due to the pressure caused by the anode 66. Figure 5 is obtained from the diagram.

[0041] like Figure 1 As shown, the material accumulation 64 is formed by an annular protrusion, which surrounds the fluid passage 60 at the coupling body 30 and is an integral component of the coupling body 30. In addition, the annular material accumulation 64 is triangular in cross section and two adjacent triangular legs mutually limit an opening angle α at their tops, which is about 80°. Figure 1 In the solution, the triangular material accumulation 64, viewed in cross section, transitions into boundary surfaces 78, 80 both on the outer circumference and on the inner circumference, each of which is perpendicular to the longitudinal axis 22. In this way, the material accumulation is supported during reshaping within the scope of the welding method by the annular boundary surfaces 78, 80 adjoining the material accumulation 64 on the foot side. In addition, an annular further support surface 82 adjoins the boundary surface 78 on the outer circumference, which further support surface is disposed toward the inner circumference. Figure 1 The support surface 82 has an inclination angle β of about 30° relative to the horizontal plane when viewed in the viewing direction of . Such a support surface 82 also contributes to the favorable reshaping behavior of the material accumulation 64 within the scope of the welding method. The support surface 82 then transitions into the adjacent tool contact surface 58 on the outer circumference, and on the inner circumference, the inner boundary surface 80 delimits the threaded area 62 of the coupling body 30. The inclined support surface 82 also allows an undisturbed flow of material in the region of the edge sides of the triangular material accumulation 64 within the scope of the reshaping during the welding process, so as to obtain a geometrically optimally constructed weld nugget 74. In this case, the two boundary surfaces 78, 80 are located in a common plane.

[0042] according to Figure 2 The embodiment of the coupling body 30 basically corresponds to the embodiment according to Figure 1Embodiment, with the following description, the triangular material accumulation portion 64 in cross section is smaller than according to Figure 1 The material accumulation section 64. Thus, according to Figure 2 The reduced material accumulation can be sufficient to produce a fixed welded connection between the coupling body 30 and the accumulator housing part 20 within the projection welding range. In a further production method step, the separation element 12 is then introduced together with the support 46 from above into the lower accumulator housing part 20, and the edge bead 50 of the separation element 12 is clamped in the receiving portion 52 of the lower accumulator housing part 20 by means of the fixing ring 48. The upper accumulator housing part 18 is then placed on top and, as already described, a fixed connection is produced along the weld seam 42 between the two accumulator housing parts 18, 20 by means of laser welding or a similar method. The hydraulic accumulator thus completed can then be filled with an operating gas, such as nitrogen, at a predeterminable pressure on its gas side or into the further media space 16 via the upper fluid connection 24, which is then hermetically sealed by the plug or solder 26.

[0043] In principle, there is the possibility of arranging a coupling body 30 on the gas side, as described, i.e. the solder 26 can be omitted and the coupling body 30 can be fixed by projection welding, as described, on the upper side of the upper accumulator housing part 18 in the region of the edge of the upper fluid connection 24. By means of such a coupling body 30 (not shown), the hydraulic accumulator can also be refilled with working gas if necessary and the gas side can be closed, for example by inserting a screw-in plug into the fluid passage 60 of the coupling body 30 (not shown).

[0044] In principle, there is the possibility of also fastening the gas valve to the gas side of the accumulator using the described resistance welding, which is particularly advantageous for accumulators that can be refilled on the gas side. If the term fluid is used above, this includes not only liquids such as hydraulic oil but also gases such as nitrogen.

[0045] At this point it should be emphasized that the solution according to the invention is not necessarily limited to hydraulic accumulators in the form of diaphragm accumulators, but can instead always be used there when a corresponding coupling body with a fluid passage is to be fastened to an accumulator housing of a pressure accumulator with a corresponding fluid connection point.

Claims

1. A method for producing at least a part of a hydraulic accumulator, the method comprising at least the following method steps: - providing an accumulator housing part (20) having at least one fluid connection point (28), - providing a coupling body (30) with a fluid passage (60), said coupling body having a material accumulation (64) on one of its free ends, - placing the material accumulation (64) against the accumulator housing part (20) in such a way that a fluid connection point (28) in the accumulator housing part (20) is fluidically connected to a fluid passage (60) of the coupling body (30), - melting the material accumulation (64) by means of a welding method, - joining the coupling body (30) and the accumulator housing part (20) together with a predeterminable contact pressure and a predeterminable stroke, and - Allowing the resulting welded joint (70) to cool.

2. The method according to claim 1, characterized in that Resistance pressure welding, in particular resistance projection welding, is used as the welding method.

3. The method according to claim 1 or 2, characterized in that: In the context of resistance projection welding, the connecting body (30) is placed against the accumulator housing part (20) serving as cathode (72) with a predeterminable contact pressure by means of an anode (66).

4. The method according to any one of the preceding claims, characterized in that The separating element (12) is inserted into an accumulator housing part (20) with a welded-on connecting body (30) by means of a bracket (46), and a further accumulator housing part (18) is subsequently welded to the accumulator housing part (20) to form the hydraulic accumulator.

5. A hydraulic accumulator, in particular produced by means of a method according to any one of the preceding claims, comprising an accumulator housing (10) and a separating element (12) arranged in the accumulator housing, which separates two media spaces (14, 16) from one another, wherein: The accumulator housing (10) has at least one fluid connection point (28) which leads into an adjacent medium space (14), and the hydraulic accumulator has a coupling body (30) with a fluid passage (60), the coupling body being fixedly connected to the accumulator housing (10) by means of a welded connection structure such that the fluid connection point (28) of the accumulator housing (10) is fluidically connected to the fluid passage (60) of the coupling body (30), characterized in that the welded connection structure (70) between the accumulator housing component (20) and the coupling body (30) is formed by a reshaped material accumulation (64) of the coupling body (30), the material accumulation forming a weld core (74) having a through opening (76) as part of the fluid connection.

6. The hydraulic accumulator according to claim 5, characterized in that The material accumulation (64) is formed by an annular projection which surrounds the fluid passage (60) on the coupling body (30) and is an integral component of the coupling body (30).

7. The hydraulic accumulator according to claim 5 or 6, characterized in that: The annular material accumulation ( 64 ) is triangular in cross section and has an opening angle (α) of 70° to 110°, preferably 80° to 100°, particularly preferably 90°, at the top.

8. The hydraulic accumulator according to any one of claims 5 to 7, characterized in that The material accumulation (64) transitions on the outer circumference and / or on the inner circumference into boundary surfaces (78, 80) which are perpendicular to the longitudinal axis (22) of the coupling body (30).

9. The hydraulic accumulator according to claim 8, characterized in that The outer boundary surface (75) transitions at a predeterminable angle (β) on the outer circumference into a support surface (82) which is part of the one free end face of the coupling body (30).

10. The hydraulic accumulator according to claim 8 or 9, characterized in that: The inner peripheral boundary surface (80) transitions into the threaded region (62) of the coupling body in a vertical extension viewed parallel to the longitudinal axis (22) of the coupling body (30).

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