Glass-metal feedthrough for a pressure sensor

Abstract

The invention relates to a glass-metal feedthrough (2) for a pressure sensor (1), at least comprising: - a substantially cup-shaped metal main part (2.4) having a first and a second end face (2.5, 2.6), - a metal contact pin (2.1) for electrically contacting a pressure measuring cell (3), said metal contact pin being fused into the main part (2.4) via a glass element (2.2) over part of the length of the metal contact pin in such a way that the contact pin (2.1) protrudes from the glass element (2.4) at a first and a second end; - a first hydraulic pressure transmission channel (11), which is formed in the main part (2.4) and an opening of which terminates the channel on a lateral surface (2.3) of the cup-shaped metal main part (2.4), the lateral surface connecting the first and second end faces (2.5, 2.6) of the main part; and - a ball (2.9), which is provided on the opening and which is fluid-tightly, preferably pressure-tightly, welded to the main part (2.4).

Description

[0001] Glass-to-metal feedthrough for a pressure sensor

[0002] The invention relates to a glass-metal feedthrough for a pressure sensor, a pressure sensor with such a glass-metal feedthrough and a method for manufacturing a pressure sensor.

[0003] Pressure sensors are used to measure pressure and / or to control, regulate, and / or automate processes within a system. Pressure sensors are used in automation technology across a wide range of industries, including the chemical and food industries, to name just a few important application areas.

[0004] A pressure sensor typically comprises a pressure sensing cell and sensor electronics connected to the pressure sensing cell. The pressure sensing cell includes an electromechanical transducer that converts the response of a pressure-sensitive element into an electrical signal, which is then received by the sensor electronics and made available for further evaluation and / or processing.

[0005] The pressure sensor can be designed as an absolute pressure sensor, a gauge pressure sensor, or a differential pressure sensor. While an absolute pressure sensor measures the pressure as an absolute difference relative to a vacuum, a gauge pressure sensor measures the pressure of a process medium relative to a reference pressure. This reference pressure is typically the atmospheric pressure at the installation location of the pressure sensor.

[0006] A differential pressure sensor, on the other hand, detects the difference between two pressure readings of the process medium. Differential pressure sensors are used, for example, in tanks for level measurement or in pipelines for flow measurement.

[0007] While the measuring pressure of the process medium is applied to the surface of the pressure-sensitive element facing the process via the separating membrane, the surface of the pressure-sensitive element facing away from the process is subjected to vacuum, atmospheric relative pressure, or, in the case of a differential pressure sensor, to another measuring pressure.

[0008] To transmit the pressure(s) of the process medium to the pressure-sensitive element, hydraulic channels filled with a transmission fluid are implemented in the pressure sensor. This transmission fluid is typically an oil, such as silicone oil. The transmission fluid is filled into the hydraulic channels via special oil filling tubes, which must be integrated into the pressure sensor. This requires a filling adapter, which is inserted over the oil filling tube during the filling process and sealed with an O-ring when in place.

[0009] The disadvantage here is that this process is time-consuming and expensive to manufacture.

[0010] The invention is therefore based on the objective of providing a remedy for this problem.

[0011] The problem is solved according to the invention by the glass-metal feedthrough for a pressure sensor according to claim 1, the pressure sensor according to claim 9 and the method according to claim 10.

[0012] The glass-metal feedthrough according to the invention for a pressure sensor comprises at least: a substantially cup-shaped metallic base body with a first and a second end face; a metallic contact pin for electrically contacting a pressure measuring cell, which is fused into the base body over a portion of its length via a glass body such that the contact pin protrudes from the glass body at a first and a second end; a first hydraulic pressure transmission channel formed in the base body, which terminates with an opening on a lateral surface of the cup-shaped metallic base body connecting the first and second end faces of the base body; a ball arranged on the opening, which is fluid-tight, preferably pressure-tight, welded to the base body.

[0013] According to the invention, a glass-to-metal feedthrough is proposed which has a laterally arranged opening, i.e., on the outer surface, for filling with the transmission fluid, through which the fluid is filled into the pressure transmission channel. After filling, the opening is closed by means of a ball. Such a glass-to-metal feedthrough offers the advantage that no oil filling tubes are required, thus simplifying the design.

[0014] An advantageous embodiment of the glass-to-metal feedthrough according to the invention can provide that the base body is essentially rotationally symmetrical with respect to its outer contour, and that a first partial region of the outer surface around the opening is flattened, preferably planar. A further advantageous embodiment of the glass-to-metal feedthrough according to the invention can provide that at least one further hydraulic pressure transmission channel is formed in the base body, which terminates at the outer surface of the cup-shaped metallic base body with a further opening, and that at least one further sphere is provided, which is arranged on the further opening and which is fluid-tight, preferably pressure-tight, welded to the base body. In particular, the glass-to-metal feedthrough can provide that a second partial region of the outer surface around the further opening is flattened, preferably planar.

[0015] Another advantageous embodiment of the glass-metal feedthrough according to the invention can provide that the flattened first partial area and the flattened second partial area of ​​the lateral surface are of different sizes.

[0016] A further advantageous embodiment of the glass-metal feedthrough according to the invention can provide that the first hydraulic pressure transmission channel and / or the further hydraulic pressure transmission channel are designed such that the openings are arranged diametrically opposite each other on the lateral surface of the base body.

[0017] A further advantageous embodiment of the glass-metal feedthrough according to the invention can provide that the first hydraulic pressure transmission channel and / or the further hydraulic pressure transmission channel are designed such that the openings are arranged axially offset on the lateral surface of the base body.

[0018] A further advantageous embodiment of the glass-to-metal feedthrough according to the invention may provide that the first hydraulic pressure transmission channel and / or the further hydraulic pressure transmission channel are designed such that the openings are arranged on the same side of the lateral surface of the base body. A further advantageous embodiment of the glass-to-metal feedthrough according to the invention may provide that the sphere(s) is / are matched to the opening(s) such that the diameter of the respective sphere is larger than the diameter of the respective opening on which the sphere is arranged, so that the sphere(s) only partially, and in particular not completely, protrudes into the opening(s).

[0019] The invention further relates to a pressure sensor for determining the pressure of a process medium with a glass-metal feedthrough according to one of the previously described embodiments and at least one base body component, wherein a pressure measuring cell with a pressure-sensitive element is arranged in an interior of the glass-metal feedthrough, wherein at least one separating membrane is attached to the at least one base body component to form a pressure chamber, wherein at least one hydraulic pressure transmission channel filled with a transmission fluid, comprising at least the first hydraulic pressure transmission channel, is provided in the pressure sensor, via which the pressure chamber is connected to the pressure-sensitive element in order to transmit a medium pressure acting on the separating membrane to the pressure-sensitive element.

[0020] Furthermore, the invention relates to a method for manufacturing a pressure sensor, in particular according to the preceding claim, comprising the following steps:

[0021] Providing a glass-metal feedthrough according to one of the previously described embodiments, in which a pressure measuring cell with a pressure-sensitive element is arranged in an interior of the glass-metal feedthrough, wherein the ball is initially not arranged on the opening and is not welded to the base body;

[0022] Providing at least one base body component to which at least one separating membrane is attached to form a pressure chamber, wherein the glass-metal feedthrough to which at least one base body component is joined and at least one hydraulic pressure transmission channel, comprising at least the first hydraulic pressure transmission channel, is provided, connecting the pressure chamber to the pressure-sensitive element;

[0023] Filling at least one hydraulic pressure transmission channel with a transmission fluid through the opening of the glass-to-metal feedthrough;

[0024] Closing the opening in such a way that the ball is arranged on the opening and the ball is welded to the base body in a fluid-tight manner, preferably pressure-tight, by means of a weld, in particular resistance welding.

[0025] An advantageous embodiment of the method according to the invention can further provide that the closing of the opening and the further opening is carried out in such a way that the ball is arranged on the opening and the further ball on the further opening and the balls are simultaneously, i.e. at the same time in one welding step, fluid-tight, preferably pressure-tight by means of the welding, in particular.

[0026] Resistance welding will be used.

[0027] The invention is explained in more detail with reference to the following drawings. They show:

[0028] Fig. 1: a sectional view through a first embodiment of a glass-to-metal feedthrough according to the invention, Fig. 2: a sectional view through a second embodiment of a glass-to-metal feedthrough according to the invention, and

[0029] Fig. 3: a perspective view of a third variant of a glass-to-metal feedthrough according to the invention, and

[0030] Fig. 4: a sectional view through a pressure sensor for determining the pressure of a process medium with a glass-to-metal feedthrough.

[0031] Fig. 1 shows a sectional view through a first variant of a glass-metal feedthrough 2 according to the invention for a pressure sensor 1. The glass-metal feedthrough 2 has a substantially cup-shaped metallic base body 2.4, in particular made of stainless steel.

[0032] With respect to an outer contour, the base body is preferably essentially rotationally symmetrical. The metallic base body 2.4 has a stepped outer contour 2.7 on a second end face 2.6 opposite the first end face 2.5. The stepped outer contour 2.7 is realized by a tubular extension formed on the second end face 2.6 of the metallic base body 2.4. This can be produced, for example, by a machining process, in particular turning and / or milling. The tubular extension formed on the second end face 2.6 of the metallic base body 2.4 defines at least a portion of an interior space 2.8 into which the pressure measuring cell, to be described in more detail below, can be inserted, optionally together with a filler element, which will also be described in more detail below.

[0033] Several metallic contact pins 2.1 are encased in a glass body 2.2 within the base body, so that they are hermetically sealed within the base body 2.4 and electrically insulated from it. The contact pins 2.1 serve to electrically connect a pressure measuring cell 3, which will be described in more detail later. The metallic contact pins 2.1 are positioned along a portion of their length such that they protrude from the base body 2.4 at least at a first end face 2.5 and / or project into the interior space 2.8 at a second end face 2.6.

[0034] For hydraulic pressure transmission, a first hydraulic pressure transmission channel 11, 12 is formed in the metallic base body 2.4. When the glass-to-metal feedthrough 2 is installed in the actual pressure sensor 1, this channel is filled with a pressure transmission fluid. Due to manufacturing constraints, the first hydraulic pressure transmission channel 11, 12 is constructed from several parts 11.1, 11.2, 12.1, 12.2, 12.3. In the embodiment shown in Fig. 1, two hydraulic pressure transmission channels 11, 12 are implemented in the metallic base body 2.4.

[0035] A first hydraulic pressure transmission channel 11 comprises a first part 11.1 and a second part 11.2. The first part 11.1 of the first hydraulic pressure transmission channel 11 is configured such that it extends axially, i.e., parallel to the central axis 13 shown in Fig. 1, from the interior formed by the pipe connection into the base body to a first predefined depth. At the end of the first part 11.1 of the first hydraulic pressure transmission channel 11 located in the base body, a second part 11.2 is configured such that the second part 11.2 extends radially outwards within the base body 2.4. The second part 11.2 of the first hydraulic pressure transmission channel 11 terminates at the outer surface 2.3 of the base body 2.4 and forms a first filling opening there, which, in the installed state of the glass-to-metal feedthrough, serves to fill the pressure sensor with the pressure transmission fluid.

[0036] Additionally, a second hydraulic pressure transmission channel 12 is formed in the base body. The second hydraulic pressure transmission channel 12 comprises several parts 12.1, 12.2, and 12.3. A first part 12.1 of the second hydraulic pressure transmission channel 12 is formed in the base body 2.4 such that the first part 12.1 extends axially, i.e., along or parallel to the central axis 13 shown in Fig. 2, from the second end face 2.6 of the metallic base body 2.4 into a wall of the formed pipe extension to a second predefined depth in the base body 2.4. Furthermore, a second part 12.2 of the second hydraulic pressure transmission channel 12 is designed such that it extends axially, i.e., along or parallel to the central axis 13 shown in Fig. 1, from the interior formed by the pipe extension into the base body to the second predefined depth. Preferably, the second part is 12.2 of the second hydraulic pressure transmission channel 12 is configured such that it extends along the central axis 13 from the interior 2.8 to the second predefined depth in the base body 2.4. At the ends of the first and second parts 12.1, 12.2 of the second hydraulic pressure transmission channel 12 realized in the base body 2.4, a third part 12.3 is configured such that the third part 12.3 radially connects the two other parts in the base body 2.4 and extends outwards towards the outer surface. The third part 12.3 of the second hydraulic pressure transmission channel 12 terminates at the outer surface 2.3 of the base body and forms a second filling opening there, which, in the installed state of the glass-metal feedthrough, also serves to fill the pressure sensor with the pressure transmission fluid. All parts 11.1, 11.2, 12.1, 12.2, 12.3 of the two hydraulic pressure transmission channels 11, 12 can, for example,The filling opening is achieved by means of a bore. A metallic ball 2.9 is arranged on or at the first and / or second filling opening, serving to seal the filling opening pressure-tight after the pressure transmission channels 11, 12 have been filled with the pressure transmission fluid. The balls 2.9 are matched to the filling opening such that their diameter is larger than the diameter of the filling opening, so that the ball projects into the filling opening to a maximum of half, preferably a maximum of one-third, of its diameter. In particular, the balls 2.9 are not pressed into the filling opening. The balls 2.9 are permanently connected to the base body by means of welding, in particular by means of resistance welding.

[0037] Figures 1 to 3 each show a different embodiment of the glass-to-metal feedthrough 2 according to the invention, all of which are designed as described above. However, the glass-to-metal feedthroughs 2 shown in Figures 1 and 2 differ with respect to the design of the pressure transmission channels 11 and 12. In the embodiment shown in Figure 1, the first and / or second pressure transmission channel 11, 12 is formed in the base body 2.4 such that the first and second filling openings are arranged diametrically opposite each other on the outer surface 2.3 of the base body 2.4. Additionally, the individual parts 11.1, 11.2, 12.1, 12.2 of the first and second pressure transmission channels 11, 12 can be designed such that the first and second predefined depths are essentially the same.

[0038] In the variant shown in Figure 2, the first and / or second pressure transmission channel 11, 12 is configured in the base body 2.4 such that the first and second filling openings are axially offset on the outer surface of the base body 2.4. Accordingly, the individual parts 11.1, 11.2, 12.1, 12.2 of the first and second pressure transmission channel 11, 12 are designed such that the first and second predefined depths are unequal. Additionally, in the variant shown in Figure 2, the first and / or second pressure transmission channel 11, 12 is configured in the base body 2.4 such that the two filling openings are arranged on the same side of the outer surface 2.3 of the base body 2.4.

[0039] Figure 3 shows another variant of a glass-to-metal feedthrough 2 according to the invention. This variant can, in addition to or as an alternative to the variants shown in Figures 1 and 2, provide that a first sub-region 2.31 of the outer surface 2.3 around the first filling opening and / or a second sub-region 2.32 around the second filling opening is flattened. Preferably, the sub-region(s) 2.31, 2.32 are planar. Furthermore, the sub-regions 2.31, 2.32 of the outer surface 2.3 can be configured such that the flattened or planar areas have different sizes. Figure 4 shows a sectional view through a pressure sensor 1 for determining the pressure of a process medium with a glass-to-metal feedthrough 2. In the present embodiment, the pressure sensor 1 is configured as a differential pressure sensor for determining a differential pressure between a first and a second medium pressure p1, p2.However, the invention is not limited to differential pressure sensors, but can also be applied to relative and / or absolute pressure sensors.

[0040] The pressure sensor 1 comprises a glass-to-metal feedthrough, configured according to one of the previously described embodiments shown in Figures 1 to 3, and a base body component 5.1, 5.2 consisting of two halves. A pressure measuring cell 3 with a pressure-sensitive element 4 is arranged in the interior 2.8 of the glass-to-metal feedthrough. The pressure measuring cell 3 is arranged in the interior such that the pressure-sensitive element 4 is positioned in the direction of the process. While the surface of the pressure-sensitive element 4 facing the base body component 5.1, 5.2 is subjected to a first media pressure p1 of the process medium, a second pressure p2 is applied to the surface of the pressure-sensitive element 4 facing away from the base body component. In the case of a differential pressure sensor, a media pressure is also applied to the surface of the pressure-sensitive element 4 facing away from the base body component 5.1, 5.2.In the case of a relative or absolute pressure sensor, atmospheric pressure from the environment of the pressure sensor or a vacuum is applied. The deflection of the pressure-sensitive element 4, which is preferably a silicon chip, is detected by a measuring circuit 7.

[0041] The base body component 5.1, 5.2 includes an overload chamber 6, which is divided into two separate sub-chambers 6.1, 6.2 by a substantially disc-shaped overload membrane 8. The first half of the base body component 5.1 can, for example, be made of a casting, in particular a precision casting, or a forging. The second half of the base body component 5.2 can, for example, be made of steel, in particular a bar stock.

[0042] Furthermore, the pressure sensor 1 comprises two separating membranes 9.1, 9.2 which can be externally subjected to the respective pressure p1, p2, of which a first separating membrane 9.1 is attached externally to the first half of the base body component 5.1 in such a way that a first pressure receiving chamber 10.1 is formed and of which a second separating membrane 9.2 is attached externally to the second half of the base body component 5.2 in such a way that a second pressure receiving chamber 10.2 is formed.

[0043] In addition, the base body component 5.1, 5.2 each comprises a first pressure transmitter, which can be subjected to the first pressure p1 and through which the surface of the pressure-sensitive element facing the base body component 5.1, 5.2 can be subjected to the first pressure p1 via the first hydraulic pressure transmission channel 11, and a second pressure transmitter, which can be subjected to the second pressure p2 and through which the surface of the pressure-sensitive element 4 facing away from the base body component 5.1, 5.2 can be subjected to the second pressure p2 via the second hydraulic pressure transmission channel 12. The first and second pressure transmission channels 11, 12 are implemented in the glass-to-metal feedthrough 2 with the corresponding parts as described above. Furthermore, additional parts of the first and second pressure transmission channels are formed in the first and / or second base body component.

[0044] Both pressure transmission channels 11, 12 in the pressure sensor are furthermore filled with the pressure transmission fluid, e.g. a silicone oil, so that the pressure p1, p2 acting on the respective separating membrane is transmitted via the first and / or second pressure transmission channel 11, 12 to the pressure-sensitive element 4.

[0045] The second end face 2.6 of the metallic base body 2.4 forms a first, hollow cylindrical joining surface 13.1, particularly due to the pipe connection, at which the metallic base body 2.4 is joined to the first half of the base body component 5.1 with a second joining surface 13.2. The metallic base body and the first half of the base body component 5.1 are welded together in such a way that a weld seam 15 is formed on the first and second joining surfaces 13.1 and 13.2, respectively, which extends from the outer surface in a radial direction to the central axis 13 through the hydraulic pressure transmission channel without blocking it.

[0046] For welding, a beam welding process can be used, for example. In particular, a laser beam welding process in a vacuum or an electron beam welding process can be used. Preferably, the two components 2, 5.1 are welded radially around their circumference by means of a welding beam, which is preferably guided at an angle of approximately ± 45° to a normal vector of the outer surface.

[0047] To minimize the volume available to the pressure-transmitting fluid, a packing element 14, in particular a cylindrical one, can be arranged in the interior 2.8 of the glass-to-metal feedthrough 2. The packing element 14 or

[0048] The oil displacement body can be made of a non-conductive material and is preferably made of a temperature-resistant plastic that is chemically inert to the transmission fluid. Reference list: pressure sensor, glass-to-metal bushing, electrical contact pins, glazing or...Glass body, cladding surface, first flattened section of the cladding surface, second flattened section of the cladding surface, metallic base body, first end face of the cup-shaped housing component, second end face of the cup-shaped housing component, stepped outer contour, interior, spheres, pressure measuring cell, pressure-sensitive element, first half of the base body component, second half of the base body component, overload chamber, sub-chambers, measuring circuit, overload diaphragm, separating diaphragm, pressure receiving chambers, first pressure transmission channel, first part of the first pressure transmission channel, second part of the first pressure transmission channel, second pressure transmission channel, first part of the second pressure transmission channel, second part of the second pressure transmission channel, third part of the second pressure transmission channel, central axis, first joining surface of the glass-to-metal feedthrough, second joining surface of the first half of the base body component, filler material, cladding surface of the filler material, circumferential weld seam.

Claims

Patent claims 1. Glass-to-metal feedthrough (2) for a pressure sensor (1), at least comprising: a substantially cup-shaped metallic base body (2.4) with a first and a second end face (2.5, 2.6), a metallic contact pin (2.1) for electrically contacting a pressure measuring cell (3), which is fused into the base body (2.4) over a portion of its length via a glass body (2.2) such that the contact pin (2.1) protrudes from the glass body (2.4) at a first and a second end; a first hydraulic pressure transmission channel (11) which is in the base body (2.4) is formed and which terminates with an opening on a lateral surface (2.3) of the cup-shaped metallic base body (2.4) connecting the first and second end faces (2.5, 2.6) of the base body; a sphere (2.9) which is arranged on the opening and which is connected to the base body (2.4) is welded in a fluid-tight manner, preferably pressure-tight.

2. Glass-metal feedthrough according to claim 1, wherein the base body (2.4) is essentially rotationally symmetrical with respect to its outer contour and wherein a first partial area (2.31) of the lateral surface (2.3) is flattened around the opening, preferably planar.

3. Glass-metal feedthrough according to one or more of the preceding claims, wherein at least one further hydraulic pressure transmission channel (12) is formed in the base body (2.4), which terminates on the outer surface of the cup-shaped metallic base body (2.4) with a further opening, wherein furthermore at least one further sphere (2.9) is provided, which is arranged on the further opening and which is fluid-tight, preferably pressure-tight, welded to the base body (2.4).

4. Glass-metal feedthrough according to the preceding claim, wherein a second partial area (2.32) of the cladding surface (2.3) is flattened around the further opening, preferably planar.

5. Glass-metal feedthrough according to one or more of the preceding claims, wherein the flattened first partial area (2.31) and the flattened second partial area (2.32) of the lateral surface are of different sizes.

6. Glass-to-metal feedthrough after one or more of the preceding Claims, wherein the first hydraulic pressure transmission channel (11) and / or the further hydraulic pressure transmission channel (12) are designed such that the Openings are arranged diametrically opposite each other on the lateral surface (2.3) of the base body (2.4).

7. Glass-metal feedthrough according to one or more of the preceding claims, wherein the first hydraulic pressure transmission channel (11) and / or the further hydraulic pressure transmission channel (12) are designed such that the openings are arranged axially offset on the outer surface (2.3) of the base body (2.4).

8. Glass-to-metal feedthrough according to one or more of the preceding claims, wherein the first hydraulic pressure transmission channel (11) and / or the further hydraulic pressure transmission channel (12) are designed such that the openings are arranged on the same side of the lateral surface of the base body (2.4).

9. Glass-to-metal feedthrough according to one or more of the preceding claims, wherein the sphere(s) (2.9) is / are adapted to the opening(s) such that a diameter of the respective sphere (2.9) is larger than a diameter of the respective opening on which the sphere (2.9) is arranged, so that the sphere(s) (2.9) only partially and in particular not completely project(s) into the opening(s).

10. Pressure sensor (1) for determining the pressure of a process medium with a glass-metal feedthrough (2) according to one or more of the preceding claims and at least one base body component (5.1), wherein a pressure measuring cell (3) with a pressure-sensitive element (4) is arranged in an interior (2.8) of the glass-metal feedthrough (2), wherein at least one separating membrane (9.1) is attached to the at least one base body component (5.1) to form a pressure chamber (10.1), wherein at least one hydraulic pressure transmission channel (11, 12) filled with a transmission fluid, comprising at least the first hydraulic pressure transmission channel (11), is provided in the pressure sensor, via which the pressure chamber (10.1) is connected to the pressure-sensitive element (4) in order to transmit a media pressure (p1) applied to the separating membrane (9.1) to the pressure-sensitive element.

11. Method for manufacturing a pressure sensor, in particular according to the preceding claim, comprising the following steps: Providing a glass-metal feedthrough (2) according to one or more of claims 1 to 9, in which a pressure measuring cell (3) with a pressure-sensitive element (4) is arranged in an interior (2.8) of the glass-metal feedthrough (2), wherein the ball (2.9) is initially not arranged on the opening and is not welded to the base body (2.4); Providing at least one base body component (5.1) to which at least one separating membrane (9.1) is attached to form a pressure chamber (10.1), wherein the glass-metal feedthrough (2) to which at least one base body component (5.1) is joined and at least one hydraulic pressure transmission channel (11) comprising at least the first hydraulic pressure transmission channel is provided, which connects the pressure chamber (10.1) to the pressure-sensitive element (4); Filling the at least one hydraulic pressure transmission channel (11) with a transmission fluid through the opening of the glass-metal feedthrough (2); Closing the opening such that the ball (2.9) is arranged on the opening and the ball (2.9) is welded to the base body (2.4) in a fluid-tight, preferably pressure-tight manner by means of a weld, in particular resistance welding.

12. Method according to the preceding claim and glass-to-metal feedthrough according to claim 3, wherein the method further provides that the closing of the opening and the further opening is carried out in such a way that the ball (2.9) is arranged on the opening and the further ball (2.9) is arranged on the further opening and the balls (2.9) are welded together simultaneously, fluid-tight, preferably pressure-tight by means of welding, in particular resistance welding.

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