Method for manufacturing a vacuum switching tube

Abstract

The present invention relates to a method for joining housing components in the manufacture of a vacuum switching tube, wherein the housing components are designed with a wall (22) encompassing a construction space, and wherein the method comprises at least the following process steps: i) Coaxial alignment of at least two housing components; ii) Bringing into contact the joining points (20) of the walls (22) of the housing components; iii) Partial, spatially limited joining of the housing components, and iv) Complete joining of the housing components, wherein v) At least one further work step takes place between process steps iii) and iv).

Description

[0001] The present invention relates to a method for producing a vacuum interrupter. The present invention further relates to a vacuum interrupter produced by a corresponding method and to a semi-finished product for producing a vacuum interrupter.

[0002] During the manufacture of a vacuum interrupter, various housing components and parts often have to be joined together in a vacuum-tight manner. In particular, metals and ceramic materials must be bonded together or to each other.

[0003] However, metal and ceramic components are technologically difficult to join together in a gas-tight or vacuum-tight manner, which is related to surface energies and wetting properties. To enable such connections between such materials, intermediate layers of active and passive solders are often used, or the ceramics are coated with metal. Furthermore, the pairing of the different material combinations with intermediate solder layers must also be considered in order to minimize the influence of thermal stresses in the subsequent process or during soldering. However, precise alignment is usually difficult in this case.

[0004] Other solutions based on carbon as well as organic and inorganic compounds may contaminate the vacuum process or require increased processing time, for example due to curing.

[0005] In addition, conventional metallizations of ceramics are used in layer thicknesses of less than 10-20 µm on the bonding surfaces, thus precluding direct fusion welding. Furthermore, commonly used ceramics are sensitive to thermal shock.

[0006] To join the housing components, the multiple assemblies are usually secured to each other and aligned coaxially using complex fixtures and jigs. This requires a high level of manual effort and is prone to errors, which can lead to leaks in the vacuum interrupter and thus cause rejects. Shifts in the orientation of the joining partners relative to each other can affect the flow of the solder during the vacuum brazing process and lead to material accumulation in the zone for critical arcing. This can negatively impact the insulating effect of the ceramic and hinder or prevent mechanical functionality.

[0007] The prior art solutions therefore still have potential for improvement. In particular, such solutions have potential for improvement with regard to the reliable and reproducible production of vacuum interrupters, particularly with regard to a step of connecting or joining their housing components.

[0008] The object of the present invention is therefore to at least partially overcome the disadvantages known from the prior art. In particular, the object of the present invention is to provide a solution by which the production of vacuum interrupters, in particular the joining of housing components, can be improved.

[0009] The object is achieved according to the invention at least in part by a method having the features of claim 1. The object is further achieved according to the invention at least in part by a vacuum interrupter having the features of claim 9, such as by a semi-finished product having the features of claim 10. Preferred embodiments of the invention are described in the subclaims, in the description or the figure, wherein further features described or shown in the subclaims or in the description or the figure can represent an object of the invention individually or in any combination, unless the context clearly indicates the opposite.

[0010] A method is described for joining housing components in the context of manufacturing a vacuum interrupter, wherein the housing components are formed with a wall enclosing a construction space, and wherein the method comprises at least the following method steps: i) Coaxial alignment of at least two housing components; ii) bringing into contact the joints of the walls of the housing components; iii) Partial, spatially limited joining of the housing components, and iv) Complete joining of the housing components, whereby v) at least one further working step is carried out between process steps iii) and iv).

[0011] Such a process enables improved production of vacuum interrupters and also allows improved quality of vacuum interrupters manufactured accordingly.

[0012] In detail, the method described here is used to produce vacuum interrupters. In particular, a plurality of housing components can be connected or joined to create the housing of a vacuum interrupter. Such vacuum interrupters can be used, in particular, as components of switchgear, such as medium- or high-voltage switchgear, which operates with a vacuum in the interior.

[0013] The housing components are designed with a wall that encloses a construction space. For example, the housing components are tubular in design. The corresponding contacts of a switching device, for example, can be formed in the interior or construction space of the vacuum interrupter produced.

[0014] To produce the vacuum interrupter or its housing, the housing components are arranged coaxially with one another according to process step i). With a coaxial arrangement of the housing components to be joined, the joints of the housing components to be joined are aligned adjacent to one another. The joints are, in particular, the end faces of the walls to be joined. This allows a gas-tight and vacuum-tight connection to be created, or a joined housing for a vacuum interrupter can be produced from the housing components, which is gas-tight and vacuum-tight under the operating conditions of the vacuum interrupter.

[0015] According to process step ii), the joints of the walls of the housing components are brought into contact and thus the adjacent end faces of the housing components are brought into contact.

[0016] In this position, according to process step iii), a partial, spatially limited joining of the housing components and thus a partial, spatially limited joining of the joints takes place. Thus, in contrast to the prior art solutions, in this process step, the joining positions of the respective housing components are not directly joined or connected to one another; rather, the joining positions are only spatially limited, i.e., connected to one another at defined points or areas. At this stage of the process, a gas-tight connection between the housing components does not yet exist; instead, process step iii) merely creates a pre-fixing.

[0017] The final, complete fixation and thus the final joining takes place according to the invention according to process step iv), namely a complete joining of the housing components, particularly along the entire joining points. After this process step, the connection of the housing components is thus designed in such a way that it can withstand the operating conditions, in particular a defined vacuum, of the ultimately generated vacuum interrupter in a gas-tight and vacuum-tight manner.

[0018] According to the invention, at least one further work step is performed between process steps iii) and iv). Accordingly, the pre-fixing created in process step iii) serves, in particular, to ensure that the process step performed between process steps iii) and iv) can be carried out smoothly and without undesired relative movement of the partially joined housing components.

[0019] In particular, this process step is a transport step, or a transporting or other handling step, which can be carried out without any problems due to the pre-fixing. In principle, however, this process step can also simply involve storage for a limited period of time.

[0020] The present invention thus solves the problem of temporarily or permanently securing the different joining components, i.e., the housing components, to one another in order to subject them to subsequent final fixing, such as vacuum brazing at temperatures of, for example, > 700°C. Furthermore, this is achieved with only a low thermal load on the joining components.

[0021] For example, the spatially limited fixation of the housing components to one another can be achieved purely at specific points or through a limited surface connection. Furthermore, spatially limited fixation can, at best, be achieved without damaging the substrate material, but possibly also with insignificant influences on the substrate material.

[0022] The method according to the invention thus allows two or more joining partners in a system to be easily aligned to each other, precisely aligned, and protected against mechanical stresses during transport and production. The present invention significantly supports the design with regard to automation ("bottom-up" manufacturing). Until now, it was impossible or difficult to permanently and reproducibly join metal-ceramic composites, for example.

[0023] The method according to the invention offers significant advantages over known solutions. These solutions are based on mechanical fixations and alignment methods of the housing components. In subsequent final fixation, such as a vacuum brazing process, these fixations represent additional volumes that must be heated or can represent sources of interference for process contamination. Furthermore, these methods are prone to errors according to the state of the art, for example, in that the components can slip during transport, ultimately causing the vacuum interrupter to leak and requiring complete disposal. Other methods, such as the use of auxiliary / intermediate media / layers with organic or inorganic components, require long process times to cure or ensure the fixation function.Even more challenging in the vacuum soldering process is the dissolution of contaminating components into the vacuum as the temperature increases.

[0024] In contrast, the method according to the invention offers significant advantages in terms of defined pre-fixation, which can be reliably maintained even during transport or other handling. Defects in the produced product can thus be minimized and corresponding waste can be prevented or at least significantly reduced.

[0025] The invention enables the fixation and bonding of a wide variety of components, such as ceramics and predominantly metallized ceramics, starting with a low metallization layer thickness (>2 µm). This eliminates the need for complex device-related mechanical fixations or organic / inorganic fixation media for a subsequent vacuum soldering process.

[0026] The invention can be applied to multilayer composites between one or more ceramics, with or without metallization, with active or passive solder, as well as layers of various metals without ceramic as the joining partner. For example, the method can be applied for a metallized layer thickness of a few µm, for example, less than or equal to 10 µm, up to several tens of µm, for example, up to 70 µm, approximately up to 40 µm. In principle, however, the joining partners can be made of metal, ceramic, contoured or not, with or without metallization.

[0027] Examples of material combinations include - Ceramic metallization solder; - Ceramic metallization solder copper / stainless steel / metal; - ceramic solder ceramic; - ceramic-metallization-solder-metallization-ceramic; - ceramic-metallization-solder-metal-solder-metallization-ceramic; - Ceramic-solder-metal-solder-ceramic; Example joining geometries include - Fillet weld, face weld, lap weld.

[0028] Corresponding processes for pre-fixing according to process step iii) include fusion welding and laser seam welding.

[0029] The method, or rather process step iii), can be carried out, for example, using all common beam welding processes. In the electron beam field, this can preferably be done with or, in principle, without a vacuum, whereby, in this embodiment in particular, circumferential seams can preferably be created. The present invention relates specifically to the properties of the joining partners and the use of the beam source. Within a series of tests, it was shown that an infrared laser achieved good results, which could then be even further improved. Lasers of specific wavelengths in the green spectral range were used for this purpose, although the blue spectral range was also possible.

[0030] The beams used can be effectively adapted to the existing conditions, for example by means of beam modulation, for example using spirals, wobbles, dots, circles, lines or flat grids, symmetrical or asymmetrical patterns, defocusing.

[0031] In principle, the process, and in particular process step iii), can be performed with or without a shielding gas, which further enhances the wide range of applications. Shielding gases with a reducing effect, in particular, support the joining behavior with regard to the flow of the solder(s) in the melting range.

[0032] The above statements demonstrate that the method can be easily adapted to various applications. It is quick to implement, flexible, and easily adaptable and scalable.

[0033] For example, a metallic material, such as a housing component or a solder, is heated locally or across a large area by the blasting process. Thermal conduction creates a temperature increase at the metal-solder interface, which is close to or above the softening or melting point of the solder. The pasty or molten solder is then able to wet and bond the metal as well as a metallized ceramic, or, in the case of active solder, even a ceramic without metallization.

[0034] According to one embodiment, method step iii) can be performed by selective joining, forming separate joining points. In particular, this embodiment allows for stable pre-fixing, while also allowing only very low thermal stress on the joining partners. For example, two, three, four, or five joining points can be created. In principle, ten or fewer, for example, five or fewer, joining points can thus be created. The joining points are preferably distributed at equal intervals along the joining location, for example, along the end face of the housing components.

[0035] It may further be preferred that a material-to-material bond is created in process step iii). In particular, a material-to-material bond can be created by applying a temperature that heats a joining partner or a material arranged between the joining partners above its softening point or melting point, thus creating a material-to-material bond after solidification.

[0036] For example, a metal joining partner can be heated to create a bonded joint. It is also possible to use a solder between the joining partners, i.e., the housing components.

[0037] Radiation sources, such as electron beams or laser beams, can be used as temperature sources. These can then be directed in a targeted and reproducible manner onto a joining partner or onto a material arranged between the joining partners, such as a solder.

[0038] For example, process step iii) can be carried out using a solder in such a way that the solder is heated above its softening point or melting point and thus allows a connection of the housing components after cooling.

[0039] In particular, the solder can be heated directly using a radiation source. In this embodiment, the temperature influence can initially act directly on the solder, for example by directing appropriate radiation directly onto the solder. The solder can thus be melted and, for example, transition into a doughy state, so that the joining partners, for example the metallic joining partner and the metallized ceramic, are wetted, which leads to a material-tight bond after solidification. This allows the temperature stress on the joining partners, especially on ceramic joining partners, to be kept to a minimum. Although small chippings can occur in ceramics sensitive to thermal shock, this risk can be significantly reduced and the resulting chippings are not significant in terms of functionality.This eliminates or significantly reduces the risk of joining partners being damaged by the joining process, which could potentially lead to leaks in the vacuum interrupter produced.

[0040] Alternatively, it is possible to directly heat a metal adjacent to the solder using a beam source. In this embodiment, the heat input, for example through targeted exposure to radiation such as a laser beam, can melt the metal, whereby in the transition area to the solder it changes into a pasty or molten state. Accordingly, all joining partners are wetted. While it cannot be ruled out that in this embodiment the beam energy extends to or into the transition area between the solder and the metallized ceramic, such effects can be significantly reduced.

[0041] Preferably, a solder foil can be used to join the housing components, or process step iii) can be carried out using a solder foil. In particular, a solder foil can offer significant advantages, for example, when using a laser beam and correspondingly using laser welding. Thus, with an automated solution, only the ceramic assembly with the solder foil needs to be handled, which can simplify processing. Furthermore, the susceptibility to errors can be reduced, particularly through automation processes, since the correct solder foil can be applied reliably and in the correct manner, i.e., in the correct position, for example, concentrically and without slipping. This results in a high level of reproducibility of the end product, which can also be manufactured using a short-time process.

[0042] Another advantage of using a solder foil is that even if the solder foil exhibits a flatness deviation, this is unproblematic, as this deviation no longer exists after welding. In principle, the requirements for the solder foil can therefore be lower. For example, solder foils with a comparatively small volume can be used, since component tolerances often do not need to be accommodated and the solder foil is precisely positioned during final joining. Since the solder foil does not have to perform an alignment function between the ceramic and the solder foil itself, the tooling costs for solder foil production are comparatively low. Furthermore, the solder foil can be manufactured quickly and easily.

[0043] Furthermore, since alignment and support of the solder foil during final joining are no longer necessary, very simple solder foil geometries can be used, which can fundamentally simplify their use. Furthermore, tolerances in the diameters of the housing components are less critical, since the support function of the solder foil can be essentially eliminated.

[0044] Finally, resource savings may be possible because the solder foil no longer needs to be annealed, even when high flatness requirements are met.

[0045] It may further be preferred to use a laser emitter or an electron beam emitter as the beam source. It has been demonstrated that such emitters, or in particular such radiation, are particularly suitable for enabling not only complete final joining according to process step iv), but also partial joining according to process step iii). This is because, for example, a very targeted energy input makes it easy to heat only a limited spatial area, so that process step iii) is possible with the lowest possible thermal stress on the housing components. Furthermore, the joining according to process step iii) can be carried out in a very defined and reproducible manner.

[0046] For further advantages or technical features of the process, reference is made to the description of the vacuum interrupter, the semi-finished product, the figures and the description of the figures.

[0047] Also described is a vacuum interrupter having at least two housing components which are connected to one another, wherein the vacuum interrupter is manufactured by a method as described above.

[0048] Such a vacuum interrupter can in particular be a component of a switching device also referred to as a circuit breaker.

[0049] Such a switching device can, for example, be a circuit breaker or a power contactor and be part of a medium-voltage switchgear or a high-voltage switchgear. A medium-voltage switchgear is understood to be a switchgear that can switch voltages from approximately 1 kV up to 60 kV. Furthermore, a high-voltage switchgear can be understood to be a switchgear capable of switching voltages above 60 kV. Furthermore, the switchgear can be, for example, a gas-insulated switchgear (GIS).

[0050] Such switching devices usually have a vacuum interrupter, which has a housing that is vacuum-tight under operating conditions and in which the active components, such as in particular the contacts, are arranged.

[0051] Due to the manufacturing process and the associated precisely and reproducibly joined housing components, vacuum interrupters according to the present invention can offer advantages in terms of tightness and stability.

[0052] In particular, differences between the vacuum interrupters manufactured according to the invention and conventionally manufactured vacuum interrupters can lie in the following features.

[0053] The spatially limited joining areas created by process step iii) can be identified by slight bumps or tarnish. Furthermore, particles form in the joining zone or a flat area forms on the edge or surface of the welded solder, as material changes alter the soldering process, essentially changing its flow behavior. Intermetallic phases can also be visible as small particles when, for example, ferrous metal and copper / silver are melted and mixed—basically, the materials of the solder and a metallization or a metallic joining partner.

[0054] In some cases, slight damage may also be found in the welded brazing area, as the brazing alloy does not wet non-metallized ceramic, which can lead to pores. Furthermore, deformation or flow marks of the brazing alloy due to shrinkage caused by welding can occur. Furthermore, bumps, craters, or spatter caused by the beam guidance of the beam source often cannot be ruled out, although this is irrelevant to subsequent functionality.

[0055] The features described above are particularly evident at the spatially limited joints and do not impair the basic functionality of the vacuum interrupter.

[0056] For further advantages or technical features of the vacuum interrupter, reference is made to the description of the process, the semi-finished product, the figures and the description of the figures.

[0057] Furthermore, a semi-finished product for producing a vacuum interrupter is described, wherein the semi-finished product comprises two housing components which are partially connected to one another in a spatially limited manner.

[0058] The semi-finished product thus occurs between process steps iii) and iv). It enables improved joining of housing components during the manufacture of a vacuum interrupter, as handling and transport, as well as final joining, are particularly safe and reproducible.

[0059] For further advantages or technical features of the semi-finished product, reference is made to the description of the process, the vacuum interrupter, the figures and the description of the figures.

[0060] Further details, features, and advantages of the subject matter of the invention will become apparent from the dependent claims and the following description of the figures. The figures show: Fig. 1 is a schematic representation of a structure to be joined for producing a vacuum interrupter according to an embodiment of the present invention; Fig. 2 is a schematic representation of a structure to be joined for producing a vacuum interrupter according to a further embodiment of the present invention; Fig. 3 shows the radiation pattern for a partial joining according to an embodiment of the method according to the present invention; Fig. 4 shows the radiation pattern for a partial joining according to a further embodiment of the method according to the present invention; Fig. 5 shows the radiation pattern for a partial joining according to a further embodiment of the method according to the present invention; Fig. 6 shows the radiation pattern for a partial joining according to a further embodiment of the method according to the present invention; Fig. 7 shows the radiation pattern for a partial joining according to a further embodiment of the method according to the present invention; and Fig. 8 shows the radiation pattern for a partial joining according to a further embodiment of the method according to the present invention.

[0061] In the Fig. 1 and Fig. 2 shows different combinations of joining partners.

[0062] Fig. 1 shows a ceramic housing component 10, which is to be joined to a metallic housing component 12. More specifically, walls 22 of the housing components are shown, each of which has a joint 20 facing toward the other. For joining, the ceramic housing component 10 has a metallization 14, to which a solder 16, for example, a passive solder and / or in the form of a solder foil, is applied.

[0063] Fig. Figure 2 shows a comparable design, but in which, in particular, an active solder can be used. In this design, metallization 14 is omitted.

[0064] However, a wide variety of variations are possible. Examples of structural combinations include: Ceramic housing component 10 - metallization 14 - solder 16, in particular as passive solder, - metallization 14 - ceramic housing component 10; Ceramic housing component 10 - solder 16, in particular as active solder - Ceramic housing component 10; Ceramic housing component 10 - metallization 14 - solder 16, in particular as passive solder, - metallic housing component 12 - solder 16, in particular as passive solder, - metallization 14 - ceramic housing component 10; Ceramic housing component 10 - solder 16, in particular as active solder - metallic housing component 12 - solder 16, in particular as active solder - ceramic housing component 10.

[0065] Basically, it should be mentioned that active soldering without metallization is possible, but passive soldering with metallization is preferred.

[0066] For at least partial, i.e., spatially limited joining, radiation 18, such as a laser beam or an electron beam, is used. The incidence of radiation 18 is shown in the following figures.

[0067] In the Fig. 3 shows that the radiation 18 is directed axially onto the solder 16, here embodied as a passive solder. For example, the radiation 18 can locally melt the solder 16 and thus wet the metallization 14, or the solder 16 can be heated to its softening point, which in turn wets the metallization 14. These alternatives apply in principle and independently of the respective design of the layer structure or structural design of the components to be joined.

[0068] According to Fig. 4, the radiation 18 is directed at an angle of approximately 45° to the axial direction onto the solder 16, here designed as a passive solder, and may or may not hit the metallization.

[0069] According to Fig. 5, a metallic housing component 12 is provided on the solder 16, which is designed in particular as a passive solder. The radiation 18 is according to Fig. 5 is directed at the metallic housing component 12 at an angle of approximately 45° to the axial direction and may extend into the solder 16, but does not come into contact with the ceramic housing component 10.

[0070] For example, in this embodiment, the radiation 18 can heat the metallic housing component 12 selectively or over a large area, whereby the solder 16 also heats up, for example, to melt or soften and thus achieve wetting of the adjacent components. This can be achieved, in particular, with radial irradiation, as in Fig. 6 shown.

[0071] In Fig. 6 shows that different radiation 18, which can preferably be used individually, i.e., not in combination, can be directed in different ways onto the solder 16, in particular configured as passive solder, or the metallic housing component 12. For example, the radiation 18 can be directed radially into the solder 16, into the metallic housing component 12, or at an angle to the axial direction, for example, of 45°, into the metallic housing component 12, or axially into the metallic housing component 12.

[0072] According to Fig. 7, the metallic housing component 12 can have a very slight, for example point-shaped, contact with the solder 16, which is designed in particular as a passive solder, wherein the radiation 18, again preferably not in combination, is directed at an angle of, for example, 45° to the axial onto the contact or into the immediate vicinity, so that a minimal influence occurs.

[0073] In the Fig. Figure 8 shows an exemplary example of a multiple composite comprising two ceramic housing components 10, each with metallization 14, adjacent to each of which a solder 16, in particular formed as a passive solder, and a metallic housing component 12 is provided between the layers of solder 16. Heat is again introduced by means of radiation 18 introduced radially into the solder 16 or into the metallic housing component 12.

[0074] In principle, it is evident from the above figures that corresponding radiation 18 can be directed onto the solder 16 or the metallic joining partner 12 in a variety of ways, such as radially, axially, or at an angle between the radial and axial directions. This allows for the advantageous pre-fixation according to the invention. Final joining can be carried out, for example, in a furnace, for example, under vacuum.

[0075] Furthermore, all body edges, i.e. the edges of the housing components 10, 12 or of the solder 16 formed as a solder foil, can be radially offset flush with one another.

[0076] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

[0077] Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention. List of reference symbols 10 Ceramic housing component 12 metallic housing component 14 Metallization 16 lots 18 Radiation 20 joints 22 wall

Claims

[1] Method for joining housing components in the context of the production of a vacuum interrupter, wherein the housing components are formed with a wall (22) encompassing a construction space, and wherein the method comprises at least the following method steps: i) Coaxial alignment of at least two housing components; ii) bringing joints (20) of the walls (22) of the housing components into contact; iii) Partial, spatially limited joining of the housing components, and iv) Complete joining of the housing components, whereby v) Between process steps iii) and iv) at least one further work step is carried out. [2] Method according to claim 1, characterized by that process step iii) is carried out by selective joining with the formation of separate joining points. [3] Method according to claim 1 or 2, characterized bythat a material-to-material connection is created in process step iii). [4] Method according to claim 3, characterized by that method step iii) is carried out using a solder (16) in such a way that the solder (16) is heated above its softening point or melting point and thus creates a connection between the housing components after cooling. [5] Method according to claim 4, characterized by that the solder (16) is heated directly using a beam source. [6] Method according to claim 4, characterized by that a metal adjacent to the solder (16) is directly heated using a beam source. [7] Method according to one of claims 4 to 6, characterized by that process step iii) is carried out using a solder foil. [8] Method according to one of claims 1 to 7, characterized bythat the process step carried out between process steps iii) and iv) comprises transporting or storing. [9] Vacuum interrupter, comprising at least two housing components which are connected to one another, characterized by that the vacuum interrupter is manufactured by a method according to one of claims 1 to 8. [10] Semi-finished product for the manufacture of a vacuum interrupter, characterized by that the semi-finished product comprises two housing components which are partially, spatially limited, connected to each other.

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