DE102018114246A1 - Housing with at least one cooling water channel and method for its production - Google Patents

Abstract

A housing is proposed that is particularly suitable for water-cooled electric motors. The housing comprises a first housing part, which was produced by casting and a second housing part, which was produced by forming. Both housing parts are connected to each other by friction stir welding, so that one or more cooling water channels can be formed in a simple manner.

Description

As part of electromobility, ever higher power densities are demanded for electric motors. The waste heat generated during operation of the electric motors can best be dissipated using a liquid medium (cooling water).

The current state of development is the housing of electric motors with water cooling, which consist entirely of one or more cast parts.

If the motor housing consists of a cast part, then the cooling channel (s) can only be introduced with the help of lost cores. This is very complex and only partially suitable for large-scale production. Despite the great effort, the cross-sections of the cooling channels are relatively large due to the manufacturing process. As a result, the cooling water volume in the housing is relatively large. As a result, the heat transfer from the motor housing to the cooling water is not optimal and the large cooling water volume increases the system weight.

If the individual parts of the housing are manufactured using the die-casting process, there are more degrees of freedom in the design and dimensioning of the cooling water channels. However, die-cast parts with complex geometries are expensive to manufacture and the individual parts must then be connected to one another in a liquid-tight manner.

An alternative manufacturing method for creating cooling water channels in the motor housing are cast-in pipes, which form the later cooling channels. This process is also very complex and only suitable for large series to a limited extent.

There is therefore a need for motor housings with water cooling, in particular for electric motors or generators, which are inexpensive, easy to automate and can be economically produced in large and large quantities.

Electric motors or generators are summarized below under the generic term "electrical machine". In connection with electromobility, electric motors are also used as generators during recuperation. Even if only one electric motor is mentioned in connection with the invention to simplify the language, generators are always included.

The above object is achieved according to the invention by a housing comprising a first housing part and a second housing part, the first housing part being produced by casting, the second housing part being produced by shaping, the first housing part and the second housing part delimiting at least one cooling water channel and wherein the first housing part and the second housing part are sealingly connected to one another by at least one weld seam, which was produced by friction stir welding.

In this way it is possible to take advantage of casting without (lost or sand) core, namely to be able to produce a complex geometry in large numbers relatively inexpensively and reliably. In the motor housing according to the invention, the later cooling channels are cast into the first housing part as depressions. The second housing part, which is produced according to the invention by shaping and has a relatively simple geometry, is placed on the first housing part and connected to it in a sealing manner by friction stir welding.

To cast the first housing part, for example in the die casting process, slides or other movable parts can be used. These movable ones are not replaced with every new casting, but are often reused, in contrast to a lost core. This creates closed and, if necessary, very small cooling channels with the desired geometry. It is also possible to insert the cooling ducts into the first housing part by machining (milling, turning, ...).
The effort to manufacture these cooling channels is comparatively low. In terms of production technology, the hybrid motor housing according to the invention is particularly advantageous because it can be produced inexpensively and reliably.

Because the second housing part is produced by reshaping, the costs for producing the second housing part are comparatively low. For example, a second housing part can be produced by cutting a sheet metal that is folded or bent. However, it is also possible to produce the second housing part by cutting an extruded tube or another extruded hollow profile to length.

The second housing part can also be produced from sheet metal by deep drawing or by extrusion. All of these forming processes have been tried and tested for decades and can be produced in particular in large and large quantities with low costs and high process reliability.

Friction stir welding as the central method for joining these two housing parts has the particular advantage in connection with the invention that the weld seams are liquid-tight. This is not the case with conventional welded connections, such as inert gas welding. In addition, the heat input into the housing parts and so that the delay in friction stir welding is comparatively low.

By combining the advantages of a cast first housing part, a second housing part produced by shaping and the welding method according to the invention, it is possible to provide an optimal geometry of the cooling channels in a process-reliable, cost-effective manner, so that the weight of the housing according to the invention and the volume of the cooling water channels formed in the housing is minimized. Both aspects are of great importance against the background of the demand for the lowest possible system weight.

The first and the second housing part can also consist of different materials, such as an aluminum casting alloy and an aluminum wrought alloy.

The following alloys are particularly suitable for production in the die casting process; SilOMg (Fe); SIL2 (Fe); Si9Cu3 (Fe); Si12Cu1 (Fe) and Al Mg9.

The first housing part can preferably be made of Al alloys, for example 6-14 percent by weight silicon; 0-2 percent by weight magnesium. Other possible main alloying elements are copper, iron, manganese. In general, the aluminum portion of the first housing part is a maximum of about 95% and the silicon portion is usually over 5%.

In the wrought alloy, the aluminum content is usually over 90%, in particular over 95%, in particular over 97%. The silicon content is usually well below 5%, especially below 2%.

The rule for cast alloys is that they usually have a certain amount of hydrogen unintentionally and therefore e.g. cannot be joined, or only very poorly, with fusion welding processes, otherwise pores will form. These pores do not occur when using the friction stir welding process, so that the weld seam is liquid-tight.

Die casting and permanent mold casting (low pressure die casting) are particularly suitable as casting processes.

The first and the second housing part can also consist of very different materials, such as an iron casting material and an aluminum wrought alloy.

Magnesium die casting for the first housing part in combination with aluminum sheet (second housing part) is also suitable if a particularly light housing is required.

In a further advantageous embodiment of the invention, the first housing part and the second housing part are arranged at least in regions concentrically / coaxially with one another and the at least one weld seam produced by friction stir welding has a closed shape, for example the shape of a circle. Then the production of the at least one weld seam is easiest to implement in terms of production technology. As a rule, the at least one weld seam must have a closed shape, i. H. when the weld seam is made, the starting point of the weld seam is reached again and "overwelded". It is then ensured that no liquid can escape from the cooling channel or channels between the first housing part and the second housing part. As a rule, at least two weld seams are present in a motor housing according to the invention. One at the first end of the second housing part and a second at the opposite end of the second housing part.

It has proven to be advantageous if the at least one weld seam produced by friction stir welding is designed as an overlap seam. Then smaller manufacturing tolerances can be compensated for in both the first housing part and the second housing part without loss of quality. This is particularly advantageous because the first housing part is designed as a cast part and, for reasons of cost, should be machined as little as possible after casting.

It has proven to be advantageous if the first housing part has a web in the region of the at least one weld seam. This web runs along the later weld seam and represents an accumulation of material that is shaped and dimensioned in such a way that favorable technological conditions exist for connecting the two housing parts by friction stir welding. The additional costs that may arise when casting the first housing part are very low.

The friction stir welding tool is generally attached to the second housing part by the second housing part and then pierces the second housing part and penetrates into the web of the first housing part.

In order to realize the cost advantages of the housing according to the invention in the best possible way, it is provided that the wall thickness of the second housing part is constant. This term is to be understood in such a way that, for example, the second housing part produced by deep drawing from a sheet metal blank has a largely constant wall thickness.

If the wall thickness of the second housing part varies greatly, it is generally no longer possible to produce the second housing part from semi-finished products, such as sheet metal, extruded pipes or the like, cost-effectively and reliably.

The second housing part can be a sheet metal blank, in particular a single or multiple bent sheet metal blank. The second housing part can also be produced by deep drawing, extrusion or pressing. It is also possible and in many cases advantageous to produce the second housing part from an extruded semi-finished product.

In order to increase the rigidity of the housing according to the invention, the invention provides for the first housing part and the second housing part to be connected to one another at additional points in addition to the weld seams produced by friction stir welding, which serve to seal the cooling channels. Screws, rivets, but also welding can be used. Welding methods other than friction stir welding, for example inert gas welding, can also be used.

These additional connections between the first housing part and the second housing part increase the rigidity of the motor housing, so that an even lighter construction can be realized with the same strength and load capacity.

In order to ensure that the at least one weld seam produced by friction stir welding is tight and has a closed shape, for example in the form of a circle, a material accumulation is provided at the end of the at least one weld seam which adjoins the web in the first housing part. After the self-contained friction stir weld has been completed, the friction stir welding unit is led out of the closed weld seam and guided into the material accumulation. The exit hole of the friction stir welding tool lies in the area of this material accumulation and not in the area of the closed, liquid-tight weld seam.

• Herstellen des ersten Gehäuseteils durch Gießen,
• Herstellen des zweiten Gehäuseteils durch Umformen,
• und Verbinden des ersten Gehäuseteils und des zweiten Gehäuseteils durch Rührreibschweißen, so dass sie mindestens einen Kühlwasserkanal begrenzen.

The advantages of the invention are also realized by a method for producing a housing according to one of the preceding sections, the method comprising the following steps:

• Producing the first housing part by casting,
• Producing the second housing part by forming,
• and connecting the first housing part and the second housing part by friction stir welding so that they delimit at least one cooling water channel.

The generic term includes deep drawing, extruding, bending and more. After forming and before welding both housing parts, further processing steps such as punching, drilling, cutting etc. can be carried out.

In a further advantageous embodiment of the method according to the invention, at least one self-contained weld seam is produced by friction stir welding and, after this has been done, the tool for friction stir welding is guided in the further course of the welding process such that it leaves the self-contained weld seam. As a result, the process-related exit hole of the friction stir welding tool is shifted out of the self-contained weld seam. As a result, the exit hole cannot impair the tightness of the connection between the first housing part and the second housing part.

A form of the weld seam which is particularly advantageous in terms of production engineering provides that the weld seam is arranged coaxially with a longitudinal axis of a stator of an electrical machine, which is later installed in the housing. Then it is then possible to receive the housing part, which later receives the stator, on a mandrel, which has approximately the diameter of the later stator, and to move the housing parts by rotating this mandrel relative to the radially supplied tool for friction stir welding.

It goes without saying that both the first housing part and the second housing part can be further machined if necessary after the casting or after the shaping process. For cost reasons, however, efforts will be made to reduce this machining to a minimum.

Another very favorable variant consists in arranging the second housing part on the inside of the first housing part. This has the advantage that the outside of the first housing part (and thus also the entire housing) does not have to be cylindrical, but instead force points such as flanges, brackets, thickenings, ribs etc. can be attached to the outside.

At the same time, there is the advantage that the second housing part can be an extruded and preferably calibrated tube, so that, due to the small tolerances, no or only minimal reworking inside the housing is necessary to comply with the tight tolerances for mounting the stator.

In this variant, to produce the grooves for forming the water jacket, dividable cores may be necessary due to the resulting undercut in the area of the later cooling water channels. However, it is also possible to produce the grooves by machining (turning, milling, ..).

As an alternative to this, longitudinal grooves can be introduced into the casting, in which there is no undercut. In order to nevertheless enable a water-tight and at the same time flowable water jacket, a second housing part can be used, which is locally expanded at the front and possibly at the rear.

• Eingängige schraubenförmige Kühlwasserkanäle.

In order to ensure a uniform distribution of the cooling fluid in the motor housing and at the same time to enable the cooling ducts to be manufactured easily, the following variants are possible:

• Catchy helical cooling water channels.

Multi-course helical cooling water channels, wherein there is a connection at the end of the helix opposite the connections between the two spirals for the fluid. In this variant, the connection for inlet and outlet can be arranged on the same side.

Meandering cooling channels with longitudinal grooves that are at least partially connected at the ends.

Another variant is that the motor housing is only partially cooled for manufacturing reasons. This offers the possibility of integrating consoles, thickening, ribbing and force application points into the cast body. The areas between these shaped elements then contain the cooling channels which are initially still open. These are covered over one or more, if necessary, appropriately bent sheet metal (s) and joined to a component by welding.

Further advantages and advantageous refinements of the invention can be found in the following drawing, its description and the patent claims.

All of the features disclosed in the drawing, its description and the patent claims can be essential to the invention both individually and in any combination with one another.

list of figures

• 1 bis 8 Ausführungsformen erfindungsgemäßer Gehäuse.

Show it:

• 1 to 8th Embodiments of the housing according to the invention.

Description of the embodiments

In the figures, a housing according to the invention is simplified and limited to the essentials 1 shown. The housing 1 is part of an electrical machine. Their main assemblies, namely the stator and the rotor, as well as their storage in the housing, are not shown in the figures. The housing according to the invention 1 comprises a first housing part 3 , which was produced by casting, and a second housing part 5 , which was produced by forming. Inside the first housing part 3 is a comparatively long cylindrical section 7 formed, which receives the stator (not shown). A central axis of the cylindrical section 7 , which usually coincides with the axis of rotation of the rotor (not shown) is by a dash-dotted line 9 indicated.

On the in 1 upper end is a footbridge 11 educated. In a corresponding manner, there is a web at the lower end of the first housing part 11 educated. The second housing part 5 and the first housing part 3 are in the area of the webs 11 connected to each other in a sealing manner by friction stir welding.

Top left in the 1 is schematically a tool for friction stir welding 15 shown. The tool for friction stir welding 15 includes a pen 17 , which rotates during the welding process, the second housing part 5 penetrates and so deep into the jetty 11 of the first housing part 3 penetrates that one shoulder 19 of the tool 15 during the welding process on the second housing part 5 rests. The shoulder 19 causes the welds to be smoothed 13.1 and 13.2 , The tool 15 for friction stir welding is not part of the housing 1 and only serves to explain the welding process.

The first friction stir weld 13.1 is manufactured by, for example, the first housing part 3 and the second housing part 5 are positioned relative to each other in the position shown and then a rotation of at least 360 °, but preferably more than 360 °, about the central axis 9 of the cylindrical section. If the housing parts 3 and 5 were rotated 360 ° while the tool 15 rotated for friction stir welding, then a closed weld seam is created 13.1 which in this case has the shape of a circle. The center of the circle coincides with the central axis 9 together when the the jetty 11 and the second housing part 5 concentric to the central axis 9 are arranged.

It goes without saying that not only circular closed weld seams can be produced, but also other, non-circular, but closed weld seams can be produced in a similar manner if the geometry of the first housing part 3 and second housing part 5 should make this necessary.

The first housing part 3 has a helical or helical recess in this embodiment 21 on that together with the second housing part 5 an also helical cooling water channel 23 limit. Then the cooling water (not shown, for example at the lower end, ie near the weld seam) 13.2 , in the cooling water channel 23 flows through the cooling water channel 23 and occurs at the top, ie near the weld 13.1 , out again. On the way through the cooling water channel 23 the cooling water takes the in the housing 1 heat introduced and removed by the electrical machine.

Of course, the invention is not based on this form of a helical cooling water channel 23 limited. It is important to note in connection with the invention that the geometrically relatively complicated shaped depression 21 Part of the first housing part produced by casting 3 is and the second housing part 5 in this embodiment may be a section of a tube made by extrusion.

A separate seal between the different aisles of the helical cooling water channel 23 is usually not necessary, as they have a very slight negative effect on the cooling effect. However, it is easily possible to prevent these leaks, for example by the fact that the first housing part 3 has a slightly larger diameter in the area of the helical web than in the area of the webs 11 , so that there is an interference fit between the inner diameter of the second housing part 5 and the helical bridge 25 results.

Alternatively, the first housing part 3 and the second housing part 5 along the helical footbridge 25 can be welded together at points or in the form of a helix. It is also possible in a groove (not shown) of the web 25 insert a sealing cord (not shown) or the gap that may arise between the helical web 25 and the inner diameter of the second housing part 5 to seal with a suitable sealant.

If the first housing part 3 and the second housing part 5 through the tool 15 are connected to each other for friction stir welding, in a preferred embodiment, a mandrel in the interior of the first housing part 3 introduced. The housing part 3 is in the cylindrical area 7 on the thorn 16 positioned and excited. The thorn 16 is designed in such a way that the outer contour of the mandrel largely corresponds to the inner contour of the inner housing part, at least in the area of the weld seam.

The thorn 16 has a stable rotary bearing and is equipped with an NC rotary drive, so that the housing parts 3 and 5 relative to the tool 15 can be rotated. The axis of rotation of the mandrel and the central axis of the motor housing coincide approximately. The holder of the housing parts by the mandrel 16 can be supplemented by further (active) clamping and holding devices (not shown), in particular to avoid turning away under the feed force.

In the 2 is the embodiment according to 1 with such a thorn 16 shown. Here is the tool again 15 shown for friction stir welding.

In the 3 a second embodiment of a housing according to the invention is shown. In this embodiment is on the first housing part 3 a flange 27 educated. This flange 27 can serve, for example, the housing 1 , which is later completed to an electric motor, with a gear (not shown) or other components.

Of course it is also possible to use the flange 27 so that it is part of a gearbox, like 7 shows. This is a question of the functional integration of the "electrical machine" and "gearbox" modules.

Between the flange 27 and the cylindrical portion of the first housing is a frusto-conical section 29 on the first housing part 3 educated. A corresponding manner is also on the second housing part 5 a complementary tapered section 31 educated. The weld 13.2 is in this embodiment in the region of the tapered sections 29 and 31 of the first housing part 3 or the second housing part 5 ,

In this embodiment, in addition to the weld 13.1 in the area of the end face of the first housing part 3 and a floor 33 of the second housing part 5 another optional weld 13.3 intended. In the 3 is the housing 1 with additional welds 13.1 and 13.4 been provided. The weld 13.1 corresponds to the weld 13.1 of the 1 , The optional (longitudinal) weld 13.4 is shown as a broken line. It represents a longitudinal weld, which is the first housing part 3 and the second housing part 5 connects with each other in the axial direction. The weld seam is used in many applications 13.4 only formed where the helical webs are 5 and 20 in the first housing part 3 available.

If the first housing part 3 has a longitudinal web (not shown) which is continuous in the axial direction, then the weld seam 13.4 be designed as a continuous longitudinal weld.

In this embodiment, the second housing part 5 shaped like a pot. It can be produced, for example, by deep drawing, pressing or extrusion. In this exemplary embodiment, length tolerances and / or diameter tolerances can be compensated well. Here too, a cylindrical mandrel (not shown) is inserted into the interior of the first housing part during the welding process 3 introduced. The first housing part 3 and the second housing part 5 are centered in this way and relative to the tool, not shown 15 rotated for friction stir welding.

In all welding processes according to the invention there is a relative movement of the tool 15 for friction stir welding and the housing parts 3 and 5 on. Of course, it is also possible that the housing parts during the welding process 3 and 5 stand firm and the tool 15 executes the desired relative movement.

The Indian 3 lower part of the housing 1 is not cut, but shown in a side view, so that you can see the weld 13.2 on the surface of the conical section 31 of the second housing part can be seen well.

In this side view is the end of the weld 13.2 shown. After the weld 13.2 the tool was completed as a closed circle 15 for friction stir welding (not shown) or the housing 1 so that the weld seam moves at one end 37 from the circular weld 13 moved out (in the 3 diagonally downwards) so that the inevitable exit hole 39 of the tool 15 outside the circular part of the weld 13.2 located. This means that there is a tight weld seam under all circumstances 13.2 guaranteed. At the end 37 the weld 13.2 To be able to realize as shown, should be on the first housing part 3 as well as on the second housing part 5 there is an accumulation of materials. Such accumulation of material is usually also the case with the other welds 13.1 . 13.3 and 13.4 available, but not shown in the figures.

In the 4 a section of another embodiment of a housing according to the invention is shown. In this embodiment, the cooling water channels run 23 in the axial direction. The recesses are corresponding 21 in the first housing part 3 designed as axial grooves. The second housing part 5 is a bent sheet metal blank in this embodiment, which was bent into a tube. At the joint, which is also in the longitudinal direction of the second housing part 5 extends, the second housing part 5 with the first housing part 3 in the area of a footbridge 11 sealed together. The weld 13.4 not only connects the housing parts 3 and 5 , but also seals the second housing part 5 to the surroundings.

Is not shown in the 4 a manifold through which the cooling water flows from a central entrance (not shown) into the housing 2 is fed, is distributed over a total of five cooling water channels running in the axial direction. Also a collector, which from the cooling water channels 23 leaking cooling water collects and feeds a central outlet is not shown.

The exemplary embodiments shown so far have in common that the first housing part is arranged on the inside and the second housing part 5 outside of the first housing part 3 is arranged.

Based on 5 An embodiment is shown in which the second housing part 5 is arranged inside. This exemplary embodiment nevertheless has a large number of correspondences with the first exemplary embodiment, so that reference is made to the description thereof. As from the 5 the recesses are visible 21 on the inside diameter of the first housing part 3 educated. This is a little more difficult to achieve in terms of casting technology, because a preferably reusable slide or other movable part must be used that can be drawn in radially inwards, so that the cast part 3 and the core can be separated from each other after casting. However, this can be mastered in terms of manufacturing technology. An alternative is to cut the grooves by machining after casting in the first housing part 3 contribute.

The bridges 11 respectively. 25 are formed similarly to the first embodiment. However, they are on the inside diameter of the first housing part 3 and not, as in the first embodiment, on the outer diameter of the first housing part 3 educated.

In this embodiment, the second housing part 5 and the first housing part 3 also recorded on a cylindrical mandrel (not shown) and around the central axis 9 turned. The tool 15 for friction stir welding, it first penetrates the first housing part arranged on the outside when immersed in the housing parts 3 in the area of the footbridge 11 and then partially penetrates into the second housing part 5 on.

In the 5 the helical or helical course of the cooling water channel was shown by broken lines 23 indicated by broken lines (without reference numerals).

In the 6 is a further embodiment of a housing according to the invention 1 shown, in which the cooling water channel 23 or the footbridge 21 which is meandering. In this illustration, only the second housing part is 5 shown in section. The first housing part 3 is shown in a side view. The cooling water (not shown) enters an inlet 41 in the cooling water channel 23 and then flows through the meandering cooling water channel 23 until it's finally at an outlet 43 back out of the case 1 exit.

In the 7 is a further embodiment of a housing according to the invention 1 shown. In this embodiment, the first housing part 3 of an electric motor and a gear housing 45 integrated into a component produced by casting.

To the gearbox 45 is a second gear housing part 47 with the help of a flange 49 and several screws 51 flanged. This exemplary embodiment only serves to illustrate a possible functional integration of the electric motor and transmission.

In the embodiment according to 8th the second housing part is designed as an extruded extruded profile. It has a tubular body on the four ribs 53 are molded. On these ribs 53 can mounting holes 55 be present, so the housing 1 and with it the entire electric motor on the ribs 53 can be attached.

Especially around the welds 13.1 and 13.2 To enable, the ribs produced by extrusion can be removed by punching or machining, especially at the ends.

Claims (17)

Housing, in particular for electric motors, comprising a first housing part (3) and a second housing part (5), the first housing part (3) being produced by casting, the second housing part (5) being produced by shaping, the first The housing part (3) and the second housing part (5) delimit at least one cooling water channel (23), and the first housing part (3) and the second housing part (5) are sealingly connected to one another by at least one weld seam (13) produced by friction stir welding. Housing after Claim 1 , characterized in that the first housing part (3) and the second housing part (5) are arranged at least in regions coaxially to one another, and that the at least one weld seam (13.1, 13.2, 13.3) produced by friction stir welding has approximately the shape of a circle and / or closed is. Housing after Claim 1 or 2 , characterized in that the at least one weld seam (13) produced by friction stir welding is designed as an overlap seam. Housing according to one of the preceding claims, characterized in that the first housing part (3) has a web (11) in the region of the at least one weld seam (13). Housing according to one of the preceding claims, characterized in that a wall thickness of the second housing part (5) is constant. Housing according to one of the preceding claims, characterized in that the second housing part (5) is a sheet metal blank, in particular a single or multiple bent sheet metal blank. Housing according to one of the preceding claims, characterized in that the second housing part (5) is produced by deep drawing, extrusion or pressing. Housing according to one of the preceding claims, characterized in that the second housing part (5) is made from an extruded semi-finished product. Housing after Claim 8 , characterized in that parts of the extrusion profile, in particular ribs or thickenings, are machined by punching or machining before welding, in particular in order to enable an approximately jump-shaped surface or a step in the area of the weld seams. Housing according to one of the preceding claims, characterized in that the first housing part (3) and the second housing part (5) are additionally connected to one another at one or more points in addition to the at least one weld seam (13) produced by friction stir welding. Housing after Claim 9 , characterized in that the first housing part (3) and the second housing part (5) in addition to the at least one weld seam (13) produced by friction stir welding at at least one further point by welding, in particular friction stir welding, inert gas welding, and / or screwed or riveted connections are interconnected. Housing according to one of the preceding claims, characterized in that the first housing part (3) has an accumulation of material at the end of the at least one weld seam (13.2), and that an exit hole (39) of the tool (15) for friction stir welding is located in this accumulation of material. Method for producing a housing (1) according to one of the preceding claims, comprising the following steps: Producing the first housing part (3) by casting, Producing the second housing part (5) by shaping, Connect the first housing part (3) and the second housing part (5) by friction stir welding so that they delimit at least one cooling water channel (23). Method according to the preceding method claim, characterized in that at least one self-contained weld seam (13) is produced by friction stir welding, and in the further course of the welding process a tool (15) for friction stir welding is guided such that it seals the self-contained weld seam (13 ) leaves. Method according to one of the preceding method claims, characterized in that the first housing part (3) is produced by die casting, die casting, sand casting or other casting processes. Method according to one of the preceding method claims, characterized in that the second housing part (5) is produced by rolling, bending, extruding, deep drawing and / or extrusion. Method according to one of the preceding method claims, characterized in that the first and / or the second housing part (3, 5) are machined after molding by casting or reshaping.

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