EP0999001A1 - Method and device for manufacturing a rotor for electrical machines - Google Patents

Abstract

The method involves forcing a liquid metal, especially aluminium or copper into grooves (5) and/or front ring surfaces of a toroidal laminated core (4), and solidifying. A closed evacuated housing (2,8,14) accommodating the laminated core is dipped into a gas-free molten mass of the liquid metal, and then opened so that the effect of atmospheric pressure forces the metal into the housing. The housing may be evacuated to less than 50 Torr. An apparatus for manufacturing a rotor for electric machines is also claimed.

Description

The present invention relates to a method by the preamble of Claim 1 defined genus and an apparatus for performing this Procedure.

If there are cavities or grooves or caverns of a certain body with a metal should be filled, e.g. in the manufacture of a rotor for one Short-circuit rotor motor is the case, the in the cavities or grooves of the Metal elements to be inserted into the body after the body has been formed into this body be inserted. Various methods are currently known for this.

One way to grooves or cavities of a body with a metal element fill, which in the case of a rotor of a squirrel-cage motor in the longitudinal direction or Axial direction of a cylindrical body is to metal rods, such as Copper rods to knock into the body on one face, which is also called spelling referred to as. This is very time-consuming because of the large number Copper rods must be tapped. In the case of a rotor for one Short-circuit rotor motors must also have both ends of each copper rod Short-circuit rings are connected, each individually with each copper rod end need to be soldered. This soldering of the rings is due to the high number of required solder joints are also very expensive and also has one Arrangement also has the disadvantage that defects occur at the individual solder joints can, which significantly deteriorate the quality of the rotor or this rotor as a whole can even make them unusable, since in the worst case individual copper rods are not more electrically with the rings on the front of the body are connected. Such a method is therefore also disadvantageous in that the Attaching the short-circuit rings to the individual copper rods that have been inserted is complex and is qualitatively problematic.

The usual for smaller rotors with a diameter of up to 300 mm Pouring out with aluminum according to the die-casting process is very difficult for copper small rotors applicable and is also associated with great difficulties here sealing the pressure piston at the temperatures required for copper of 1250 ° C is not controlled.

Alternatively, attempts have been made to fill the cavities of a body with metal by the body is rotated around a vertical axis, with liquid metal in the middle of the Body was introduced, which is due to the centrifugal force on the grooves in the body should distribute. However, the results of this procedure were unsatisfactory so that e.g. no high quality rotors of a squirrel cage motor could be produced.

From DE-OS 25 57 645 is a method for pouring the grooves and pouring the Short-circuit rings of short-circuit rotors of electrical AC machines in the Low pressure casting process known, with a preheated laminated core between with Recesses molded parts is inserted and the lower molding openings for flowing in liquid metal, which has a riser of a crucible stay in contact. A mandrel is inserted into the longitudinal hole in the laminated core and both molded parts become airtight in one above a cover one to the outside completed holding and casting furnace arranged pressing device used, so that the laminated core can be pressed together by the pressing device. Means of a compressed gas introduced into the crucible, liquid metal is in the grooves of the Laminated core initiated, the laminated core during this casting process a vibrator built on the pressing device is set in vibration, so that air bubbles can escape during the pouring process in order to create a voidless and to achieve flawless casting.

The present invention has for its object a method and a Device for filling cavities or grooves of a body with a liquid metal, in particular for producing a rotor for electrical machines by composite casting, proposing the disadvantages of the above described reduce or avoid known methods or devices. In particular, should a method can be proposed with which a filling of cavities or Grooves of a body, e.g. a ring-shaped laminated core, with a liquid Metal can be made of high quality, as well as a device which is suitable for performing the method.

The process product can e.g. used as a rotor for a squirrel cage motor be, the method according to the invention or the inventive Not only limit the device to it, but a variety of others Offer possible uses. The method according to the invention, like that Device to be used wherever grooves or cavities or Caverns of a certain body are to be filled with a metal without it must be a rotor of an electric motor.

The object of the invention is achieved by the method of claim 1 and a Device with the features of claim 14 solved.

Appropriate and advantageous embodiments of the invention result from the in the features defined in the subclaims.

The advantages achieved with the method according to the invention are based on the following Functionality:

The cavities of the body, e.g. a sheet metal package, which should be filled with a metal to manufacture a rotor evacuated or placed in a vacuum state, so that reduced by this Pressure is a lesser or no amount of gas in these cavities, which of the metal to be filled must first be displaced during a filling process. Farther This evacuation creates a vacuum state, which causes liquid Metal is sucked into these cavities or by an external force, e.g. Ambient air pressure or centrifugal force is pressed into these cavities. Consequently these cavities or grooves can be almost completely free of air or gas with liquid Metal such as Aluminum or copper can be filled, so that by this considerable lower gas density in the cavities, less or even no turbulence arise, as would be the case with a filling process, if the cavities with air would be filled. This turbulence-free filling of the body's cavities with one liquid metal, preferably a gas-free melt, ensures a uniform Distribution of the metal within the cavities. There is little or no gas in these If there are voids, the oxidation problems of a conventional one Avoided casting process. A conventional pouring jet forms immediately contact with an oxygen-containing atmosphere from an oxide layer, which the Properties of the product obtained adversely affected. Thus, according to the invention a deoxidizer can be dispensed with.

The body or the laminated core are preferably in an evacuated and sealed housing arranged, which in a melt of liquid metal is immersed and opened so that the external atmospheric pressure liquid metal is pressed into the housing.

The liquid metal is preferably pressed into the housing from below, so that the outside prevailing atmospheric pressure an increase in the metal in the evacuated and opened housing causes. However, it is also possible that by another external force acting on the melt, e.g. a centrifugal force, the liquid metal in enters the housing in an oblique direction or even horizontally.

With the method according to the invention it is thus possible to use a composite or Form integral casting, i.e. that a variety of cavities or grooves or Caverns can be filled or poured out in one piece at the same time that in the body obtained as the final product, the then solidified liquid metal as one Piece is available, so that e.g. in the case of a rotor for a squirrel cage motor also no subsequent processing or connection steps, e.g. Soldering or welding together. Here will the liquid metal also on the front surfaces of the body or laminated core guided.

Another advantage of the method according to the invention is that, unlike e.g. when tapping or ejecting a body, cavities or caverns can be completely filled with metal that has such a geometry, that conventional spelling is not possible. This can e.g. at a cavern or a cavity, which changes with a changing cross section and / or extends with several curvatures in the body or along the body. In a such a cavern could not be inserted from the outside because it is inserted should be bent several times, which is a complete insertion in the worst case makes impossible.

This advantage of the method with regard to the independence of the arrangement or Geometry of the cavities in the body also allows cavities with one completely new cross-section and a new course safely and reliably a high quality way to fill with metal, so that z. B. in a rotor Short-circuit rotor motor also curved or meandering rods with e.g. trapezoidal cross-section can be formed, as is the case with the method was previously impossible according to the prior art.

The external force, e.g. the atmospheric pressure can be so presses the liquid Metal into the individual cavities or grooves without a complex individual Processing of the individual cavities must be made. Because the cavities or grooves are in a vacuum state or are evacuated, the inflowing liquid metal only a little or no air pressure, so that there is little or no turbulence, which leads to an improved quality of the obtained filled body leads because the fillings of the individual cavities evenly be formed. The inflowing liquid metal is due to the low Gas quantities also only slightly or not oxidized, which further improves Contributes to the quality of the product obtained.

The liquid metal is advantageously gas and / or turbulence-free in the evacuated Cavities, which e.g. by strong evacuation or a suitable form of Cavities can be caused.

In a preferred embodiment of the method according to the invention Housing or the cavities or grooves to be filled a vacuum, the Pressure is below 50 torr, in particular below 10 torr (1 torr = 133.3224 Pa), preferably in the range of 0.01 to 1 torr.

The method is preferably carried out as already mentioned above in that additional for filling cavities and / or grooves of the body on one side of the Body an upper annular space is formed, which is also filled with liquid metal a lower annular space is formed on the other side of the body, which is also filled, both annular spaces with the filled cavities of the body are in an integral connection, i.e. that the entire structure consists from the lower annulus, filled cavities of the body, and the upper annulus, is formed from a casting, or is produced in one process step. Naturally can also be provided only a single annulus.

Alternatively to the above-mentioned embodiment, according to which the body is in a housing is given, then the interior of the housing is then evacuated, it is also possible that to carry out the method according to the invention without encasing the body or encapsulate. For this, e.g. Closure elements on the grooves or Cavity openings are provided, which when immersed in the melt be melted to allow the melt to enter.

It is advantageous that the external force that the liquid metal in the evacuated Cavity or the evacuated grooves presses, an ambient atmospheric pressure is what e.g. can be achieved in that the capsule or the body in a melt of liquid metal is immersed, so that when negative pressure is present in the cavities the atmospheric pressure on the melt causes the liquid metal to enter the Cavities or the upper and lower annular spaces of the body pressed in or introduced.

Because in the molten metal small amounts of gases, mainly hydrogen can be solved, it is advantageous to the melt before it is introduced into the degassing under vacuum to degas the solidifying Avoid melt and the resulting gas pore formation. The pre-degassing of the Melting is best done in a vacuum furnace. The gas-free metal can e.g. under protective gas before the evacuation of the housing or synchronously with it degassing by evacuation and subsequent solidification of the evacuated Melt can be melted again, whereupon the housing in it again melted gas-free metal can be immersed.

Sucking in or pushing in the liquid metal or is preferred Melt in the evacuated or underpressure cavities and / or grooves or caverns by an external force supporting the external atmospheric pressure accelerates. This supporting external force can e.g. to be gravity. Alternatively or additionally, it is also possible that the supporting external force is a Centrifugal force, i.e. the body with the cavities or caverns to be filled is rotated or thrown so that the centrifugal forces acting on the body sucking or pushing the liquid melt into the cavities of the body supported.

It is also advantageous if on the surface of the melt of the liquid metal in addition, a compressive force acts, which is also an external supportive force represents which individually or in combination with other external support forces to accelerate or support the filling of the cavities of the body liquid metal or with melt is used.

The body which has the evacuated cavities to be filled is preferred, before filling the cavities in one place airtight or vacuumtight with a Closure made of a material which is preferably the same metal as the metal that is supposed to fill the cavities of the body.

Should e.g. the cavities are filled with copper, so the housing or the Body preferably vacuum-tight at one point with a thin copper sheet closed, whereupon this body with the closed place in a copper melt is immersed. Because the copper sheet immediately closes in the copper melt melts evenly, since it is made of the same metal as the melt, the closed point abruptly in its entire cross section after the melting of the exposed thin copper sheet so that the full before melting the copper sheet pending melt enters the body through the just closed point.

Because the sheet metal to close the place is made of the same metal as that Metal in the melt, there are no mixing of different substances or alloys, which may adversely affect the quality of the received product can impact. Of course, it is also possible to target one metal other than sheet metal is used for sealing, so that the metal in the Melt together with the final metal form an alloy, which as first enters the body.

The housing or the body is advantageous in the method according to the invention or the laminated core before casting, i.e. before filling in the cavities with the liquid metal e.g. by immersion in a melt, heated so that the entering liquid metal is not already on the lower part of the capsule or body is cooled so that it solidifies. In particular, it is preferred that the body be on a Temperature of 600 ° C to 800 ° C, preferably to 700 ° C, is heated.

The solidification of the flow into the housing, e.g. through the Injected atmospheric pressure, liquid metal such that targeted Heat dissipation at the front solidification fronts against front housing plates run, with the residual solidification in which the blow hole is located in the middle of the short-circuit rings on the end face can come to rest and thus subsequently Machining processing of the composite cast rotor can be removed. A directed one Solidification of the copper melt can e.g. can be achieved in that radial Direction of the housing or laminated core or body with ring showers or similar A suitable coolant, e.g. Water, against the housing wall is injected. The coolant can e.g. applied in the middle of the case and continues to run in the axial direction after the application to the desired to obtain directional solidification of the melt.

In the case of immersion of the housing or the body in a melt, the The inventive method preferred that the depth of immersion in this melt only so is great, as for completely filling the areas to be filled with the liquid Metal is necessary, i.e. the housing or the body is only immersed to the extent that liquid metal is not significant or not at all in an upper area of the body penetrates where this is not desired.

It is preferred that the housing or the grains in the case of immersion in a Melt is so quickly immersed in this melt that the closure on the Opening the housing or the body, which e.g. is a metal plate, melts first, when the housing or the body up to its desired end position in the Melt is immersed. This can e.g. through the immersion speed, as well as the Thickness of the sealing metal plate can be influenced. This quick Immersion has the advantage that the penetration of the melt under defined Conditions are carried out so that a certain predetermined quality can be achieved.

After immersing the housing or body in the melt and after Penetration of the molten metal into the cavities or grooves of the body it is preferred in the method according to the invention that the housing or the body is cooled at a point outside the melt, so that inside the Housing or the body at the cooled point solidified metal from the liquid Melt forms, which acts as a plug or backstop for that in the housing or liquid metal in the body acts. The cooling preferably lasts until a sufficient solidification of the metal has occurred, preferably until all of the liquid metal in the body has solidified or cooled. Before the The housing or the body can also partially cool from the melt be pulled out.

In a preferred embodiment of the method is in the body, in particular in the center or in a central location running radially in the body Cavity of the body with a certain material, e.g. a ceramic core, filled in, which prevents liquid metal from entering this cavity of the body entry. This particular material, such as the ceramic core, can according to the Solidification of the filled liquid metal or the melt removed from the body be so that the body also has unfilled cavities, which in particular can be in the middle of the body.

A central bore of the laminated core or body can advantageously be through Printing plates e.g. made of steel to prevent melt in the central cavity can penetrate. Here, these printing plates by a Tie rods are tensioned against each other, which means e.g. a tight squeeze of the individual sheets of a sheet stack can be achieved. To prevent the Tie rod when the laminated core or the housing is heated, in which the Sheet pack is located, is loose, the tie rod made of a steel with very low Coefficient of thermal expansion, e.g. Invar (36% Ni) can be produced. That I expand the sheets of the sheet stack in the axial direction more than the tie rod can this results in a rigid pressing of the laminated core.

It is preferred that a material is used to manufacture the housing or body is used which is not compatible with the liquid metal, e.g. the sucked in Copper melt, reacts. Such a material can e.g. an oxidized steel sheet or be a phosphated steel sheet. Of course, other materials are just as beneficial which do not react with the liquid metal. It is advantageous to take the case out one with the melt, e.g. Copper to manufacture sparingly soluble steel prevent the melt entering the housing from no iron or anything else Absorbs material from the housing wall that comes into contact with the melt, which could reduce the electrical conductivity of the melt. This is e.g. a steel suitable, which is alloyed with 26% chromium. Steels can be used which e.g. used for thermocouple protection tubes for copper melts become.

In the method according to the invention it is preferred that certain areas of the Body after cooling the poured liquid metal or metal casting be removed. The term "body" as above and below used does not mean that this body must consist of one piece. The body can rather consist of an inner body, which has cavities to be filled has, this inner body surrounded by a housing or a capsule which is e.g. pipes arranged thereon can have to the inside of the housing including the voids of the inner body into a vacuum state Apply vacuum to one of the pipes using a pump.

Of course, the closing element of the body, e.g. the Copper end plate for vacuum-tight sealing of the body, which only after Immersion in the copper melt is melted, not immediately on the inside Body can be attached, but can also be at an outer opening of one of the pipes attached to the housing. The term used herein "Body" can thus include both the inner body alone and one Arrangement consisting of the encapsulated inner body with possibly on it attached raw. The invention can be implemented in both configurations become.

Removal of part of the body, i.e. e.g. of the housing, through Turning off made. Alternatively, other material processing methods, such as e.g. Filing, conceivable to certain parts of the body, such as the encapsulation of to remove the inner body.

It is preferred that as the above-mentioned material or metal for filling the Cavities of the body copper is used. Of course, the invention can Procedures can also be carried out with any other liquid material or metal, such as. a copper alloy or aluminum.

After filling the openings or grooves of the body or is advantageous Laminated core and / or the lower end face of the lower entry point for closed the melt. The top of the housing can then be opened are and liquid metal melt are poured from above, so that this melt with the melt which has entered from below and is preferably still liquid mixed.

The inventive device for filling voids and / or grooves Body with a liquid metal, in particular for the manufacture of a rotor, has following features: A closed housing or a capsule or encapsulation with an internal holder for the body such as for an annular laminated core; a closable opening at one end of the housing for evacuating the Interior of the housing, e.g. by connecting the end to a pump; another Opening, e.g. a standpipe with a closure, in another place or one other end of the housing for feeding or filling the liquid metal an external force in the under-vacuum or evacuated housing, the Closure when immersing the housing in a preferably gas-free melt from the liquid metal can be opened.

The closable opening for evacuating the interior of the housing is preferred Tube connected to the housing, i.e. the tube is at one end with the housing connected, the other end facing away from the housing being closable.

Of course, it is also possible to open both openings immediately without using pipes to be provided on the housing.

The inner body in the housing, which contains the caverns or grooves to be filled has, is preferably one of several sheets, in particular electrical sheets, layered core. This is particularly advantageous if a rotor is one Short-circuit rotor motor should be produced, since such a stratification of several Electrical sheets reduced or prevented adverse eddy currents.

The outer or encapsulating part of the body or the housing is preferably made of made of a material that is not with the sucked or filled metal melt responds. Such a material can e.g. an oxidized steel sheet or a phosphated one Be steel sheet. Preferably the housing can be made from a melt, e.g. in copper or aluminum are poorly soluble steel. In particular, a steel comes in for this Consider which is alloyed with about 26% chromium.

Preferred is at the closable opening for evacuating the interior of the housing Valve provided so that the interior of the housing after evacuation by means of e.g. one Pump can be sealed airtight and separated from the pump, the Vacuum condition is maintained in the housing. Of course, the closing can also by welding after evacuating the inside of the housing or others suitable means or procedures are carried out.

It is also preferred that the closable opening, e.g. between the Valve and the housing interior, a metal grid, e.g. a wire mesh plug or else Steel wool is attached, which is permeable to a gas, so that The interior of the housing can be evacuated through this wire mesh. However, this is Wire mesh plugs impermeable to an expanding melt, because of this Wire grafting causes the melt to solidify quickly because of this Wire grafting causes a quick dissipation or distribution of the heat. The Metal mesh or the wire mesh plug should have a higher melting point than that have liquid metal.

As with cooling at a point outside the melt by external cooling or Compressed air or cold air supplied is blocked by the wire mesh hardened metal formed, which is the liquid metal or the further melt prevents it from getting through to the valve so that the valve does not interfere with the valve liquid and thus hot melt comes into contact, which leads to the destruction of the Valve can lead, so that the valve can be reused in the following.

Fig. 1

einen Körner, welcher von einer erfindungsgemäßen Kapsel bzw. einem Gehäuse umgeben ist, das gerade in eine Schmelze eingetaucht wurde; und

Fig. 2

einen Rotor für einen Kurzschlußläufermotor, der mit dem erfindungsgemäßen Verfahren hergestellt wurde. Die Kurzschlußstäbe wurden durch Abdrehen des Außendurchmessers des Blechpaketes sichtbar gemacht. Um den Querschnitt der Stäbe sichtbar werden zu lassen, wurde der Kurzschlußläufer in der Zeichnung teilweise geschnitten.

The device according to the invention and a use of the product produced by the method according to the invention are described below with reference to the accompanying drawings. Show it:

Fig. 1

a grain which is surrounded by a capsule according to the invention or a housing which has just been immersed in a melt; and

Fig. 2

a rotor for a squirrel-cage rotor motor which was produced using the method according to the invention. The short-circuit bars were made visible by turning off the outer diameter of the laminated core. In order to make the cross section of the bars visible, the short-circuit rotor was partially cut in the drawing.

The inventive device according to a preferred embodiment has a Capsule or a housing 2, which consists of a cylindrical casing 2a and upper and lower end plates 2b and 2c. The top and bottom End plates 2b, 2c are with the cylindrical casing 2a on the edges welded. The upper end plate 2b has an opening at which an upper Suction pipe 8 is attached. Likewise, the lower end plate 2c has an opening to which a lower tube 14 is attached. 1 is, however only schematically, so that it is also conceivable the upper opening in the upper Form end plate 2b larger than the opening in the lower end plate 2c.

At the upper end of the upper suction pipe 8, a wire mesh 10 is attached, which liquid metal or a melt should prevent it from reaching valve 12, which closes the inside of the capsule 2 airtight with respect to the outside of the capsule 2. Air can flow in via a pump connected to the valve 12 or the upper tube 8 pumped out of the housing interior in the direction indicated by an arrow A. be so that the interior of the housing 2 is evacuated or in a vacuum state is. Of course, the capsule 2 for evacuation can e.g. also in a vacuum capsule (not shown).

The body 4 is made inside the housing 2 by means of knobs or circumferential rings 20 which e.g. can be a layered core made of sheet metal. The Body 4 has various cavities or grooves 5 through the liquid metal should be filled so that a solid metal element is formed therein. Inside the A ceramic 6 is arranged in approximately cylindrical body 4, which is particularly is heat-resistant, e.g. has a melting point of 1000 ° C or higher. This Ceramic 6 can be safely in the screw connection shown and suitable washers Be fixed or stored inside the body 4. Of course, this ceramic does not have to screwed, but can be by other suitable means, such as a Press fit in the body 4 are held.

The lower tube 14 is sealed at the lower opening with a closure 16, which e.g. is made of copper. Now the lower tube 14 with the copper closure 16 immersed in a copper melt 18, as shown, the hot one is at first Melt 18 fully to the closure 16 and causes it to be even is melted. A certain time after immersion, the Melt closure 16, so that the melt 18 evenly and quickly in the evacuated interior of the housing 2 can occur due to the pressure difference between the interior of the housing and the external ambient or atmospheric pressure.

The melt 18 shooting into the housing fills all cavities of the Housing interior 2 and is only from the wire mesh 10 of the upper tube 18th stopped. In addition to the cavities 5 of the body 4, the upper annular space 3a and the lower annular space 3b of the housing interior with liquid metal 22 from the Melt 18 filled so that a one-piece body made of metal on or in the Housing 4 is formed, which is made of metal 22a in the upper annular space 3a, connected to the metal 22b in the cavity or groove 5, connected to the Metal 22c in the lower annulus 3b.

By means of a device, not shown, the outside of the lower tube is filled with cold air flowed so that there is a gray area in the interior of the lower tube 14 made of solid metal 24 which, when sufficiently cooled, forms a plug or Backstop acts so that the liquid metal 22 inside the housing is not more can escape from this housing, even if the housing 2 from the melt 18 is removed.

The method according to the invention is described below:

First, the inside of the housing is evacuated or placed in a vacuum state, wherein air is pumped out through a valve through the valve 12. Then that will Valve 12 closed so that the interior of the housing 2 with respect to the housing exterior is hermetically sealed. At the lower opening of the lower tube 14 is the Closure 16 is provided, which is vacuum or airtight. After evacuating the Housing 2, the entire housing 2 is heated to a temperature of about 700 ° C, care should be taken that the part of the upper tube 8 with the wire mesh 10 and the valve 12 is not heated too much.

Then the evacuated and heated housing 2 with the arranged therein Body 4 immersed in the liquid melt 18 so that at a certain Immersion depth of the closure 16 melts, so that the liquid metal of the melt 18 in the inside of the housing 2 enters and fills all cavities until it is in the upper area the upper tube 8 is cooled by the wire mesh 10 and solidifies.

By simply looking at the upper tube 8 it can be determined relatively easily whether this top tube 8 is glowing, which means that the liquid metal 22 is out of the melt 18 has completely penetrated the interior of the housing, so that then with the blowing of lower tube 14 can be started with cold air, as indicated by the arrows on both Sides of the tube 14 shown so that an area is formed in the tube 14 in which solidifies or hardens the liquid metal and a plug of solid metal 24 forms. At this point, the housing 2 can be removed from the melt 18 be taken, since the liquid metal 22 located inside the housing in none Direction can emerge more from the housing 2, since it is grafted from solid Metal is held in the upper tube 8 and the lower tube 14. Instead of Air cooling can also be applied to the pipe 14 in the same place cooling jaws become.

After the liquid inside the housing has completely hardened Metal 22 becomes the housing or capsule 2 through suitable processing steps removed, e.g. the upper and lower tube can be sawn off and e.g. the cylindrical casing 2a can be turned off. It will also be in the center of the body 4 located ceramic 6 removed from the body 4, so that this body has a cylindrical cavity along its axial direction.

Fig. 2 shows a rotor 40 of a squirrel-cage motor, which with the Device according to the invention produced according to the inventive method has been. This rotor has rods 50 lying in the axial direction, which in the Cavities or grooves 5 of the body 4 have been formed. Furthermore, the respective end regions of the rods 50 by two opposite short-circuit rings 60 connected, which in the upper annulus 3a or in the lower annulus 3b, as in Fig. 1 have been formed.

Claims (17)

Process for producing a rotor for electrical machines, in particular by composite casting, a) in which a liquid metal, in particular aluminum or copper, is pressed into the grooves (5) and / or on the end face of a preferably annular laminated core (4) and then solidifies, characterized by the following features: b) an evacuated and sealed housing (2, 8, 14) receiving the laminated core (4) is immersed in a preferably gas-free melt (18) made of the liquid metal and opened, c) so that the liquid metal is pressed into the housing (2, 14) under the effect of atmospheric pressure. Method according to claim 1, characterized in that the housing (2, 8, 14) a vacuum of less than 50 torr, in particular less than 10 torr, is evacuated. Method according to one of claims 1 or 2, characterized in that the Effect of atmospheric pressure by a centrifugal force and / or an additional one compressive force acting on a surface of the gas-free melt is supported. Method according to one of claims 1 to 3, characterized in that the Melt (18) from the liquid metal before or in synchronism with the evacuation of the Housing (2, 8, 14) is evacuated. Method according to one of claims 1 to 3, characterized in that a Melt (18) is evacuated from the liquid metal, then solidifies, and later under Shielding gas is melted again, in particular synchronously with the evacuation of the Housing (2, 8, 14). Method according to one of the preceding claims, characterized in that the Sheet stack (4) before contact with the liquid metal to a temperature of about 600 ° C to about 800 ° C, preferably from about 700 ° C, is heated. Method according to one of claims 1 to 6, characterized in that by targeted heat dissipation the solidification of the liquid metal is performed so that the solidification fronts on the end against the front plates (2b, 2c) of the housing (2, 8, 14) and the residual solidification, in which a blow hole is located, in the middle of the end ring surfaces (60) comes to rest. Method according to claim 7, characterized in that for directional solidification of the liquid metal in the radial direction approximately at the level of the center of the laminated core (4) water is sprayed against the wall (2a) of the housing (2, 8, 14), preferably with Ring showers. Method according to one of the preceding claims, characterized in that the Housing (2, 8, 14) vacuum or airtight with a closure (16), in particular from the same metal as the melt, and that the housing (2, 8, 14) is so quickly immersed in the melt (18) that the closure (16) only melts when the housing (2, 8, 14) reaches a predetermined position in the Melt (18) is immersed. Method according to one of claims 1 to 9, characterized in that the central Drilling the laminated core (4) before contact with the liquid metal with a Core (6) made of high-melting material, e.g. Ceramic is filled. Method according to one of claims 1 to 9, characterized in that the central Drilling of the laminated core (4) through two tarpaulins (24), in particular made of steel, is closed so that no melt can penetrate into this central cavity, and that the pressure plates (24) are tensioned against each other by a tie rod (26), made of a material with very low coefficients of thermal expansion, especially Invar steel. Method according to one of claims 1 to 11, characterized in that according to Solidification of the liquid material, the housing (2, 8, 14) is removed, in particular through machining. Method according to one of claims 1 to 12, characterized in that according to Filling out the lower end face of the ring surface and the grooves (5) of the laminated core (4) the lower entry point for the gas-free melt (18) is closed, the housing (2, 8, 14) opened at its top and melted the molten metal from above is poured so that this melt with the from below, still liquid melt mixed. Device for producing a rotor (40) for electrical machines by compound casting a) with a closed housing (2, 8, 14) with an inner holder (20) for an annular laminated core (4), and b) with an opening for filling a liquid metal, in particular aluminum or copper, into the housing (2, 8, 14) by an external force, c) so that the liquid metal can be pressed and solidified in the grooves (5) and on the end faces of the annular laminated core (4), characterized by the following features: d) the housing (2, 8, 14) has a closable opening (8, 12) at its upper end for evacuating the interior of the housing and a riser pipe (14) with a closure (16) at its lower end, e) which can open from the liquid metal when the housing (2, 8, 14) is immersed in a preferably gas-free melt (18). Device according to claim 14, characterized in that the housing (2, 8, 14) a steel which is sparingly soluble in copper or aluminum, in particular one Steel alloyed with approximately 26% chromium. Device according to one of the preceding claims, characterized by a Valve (12) on the closable opening (8, 12) for evacuating the Housing interior. Device according to one of the preceding claims, characterized in that at the closable opening (8, 12) for evacuating the inside of the housing Wire mesh (10) is provided which is permeable for gases and for the liquid metal (22) is impermeable.

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