Casting mold for producing castings made of light metal alloys

Abstract

The invention relates to a casting mold (1a) for producing a cast part made of a light metal alloy, in particular a housing for an electric drive of a motor vehicle. The casting mould (1a) advantageously has at least one sand core (3a), which is designed and arranged in the casting mould (1a) in such a way that the at least one sand core (3a) is completely surrounded at least in sections in the circumferential direction by a light metal melt, which is filled with the casting mould in order to form the casting. The advantage of this is that a casting with a cooling channel can be produced. There is no need to introduce a borehole to form the channel. The invention further relates to a method for producing a cast part made of a light metal alloy, in particular a housing for an electric drive of a motor vehicle.

Description

Technical Field

[0001] The invention relates to a casting mold for producing a casting made of a light metal alloy, in particular a housing for an electric drive of a motor vehicle. The invention also relates to a method for producing a casting made of a light metal alloy, in particular a housing for an electric drive of a motor vehicle. Background Art

[0002] Casting molds, sand cores and methods for producing light metal castings are described, for example, in EP 3 600 718 B1, EP 3 810 357 B1, EP 2 945 760 B1, CN 105 305 704 A, DE 10

[0003] 2013 101942 B3, DE 10 2018 221826 A1 and WO 2021 / 157242 A1.

[0004] It is also known in the prior art to drill cooling channels in castings, i.e. channels in castings for guiding a coolant, which may include water, oil and / or a cooling liquid containing water. Due to process reasons, these channels are only formed as straight, which means no design freedom. Summary of the invention

[0005] The object of the invention is to produce a casting mold of the type mentioned at the outset, by means of which a casting made of a light metal alloy can be produced, in which a channel has been introduced.

[0006] Furthermore, the object of the invention is to produce a casting mold for producing a casting, which casting mold has a great degree of freedom in structural design.

[0007] According to the invention, this object is achieved in that the casting mold has at least one sand core, which is constructed and arranged in the casting mold in such a way that the at least one sand core can be completely surrounded by a light metal melt at least in sections in the circumferential direction, and the light metal melt is filled into the casting mold to form a casting.

[0008] If at least one sand core is completely surrounded in sections by the light metal melt in the circumferential direction, a channel is formed in the casting, the channel wall of which is formed by the solidification of the light metal melt around the at least one sand core, and at the same time, the at least one sand core constructs a cavity, which can be removed from the casting by mechanical treatment or thermal treatment.

[0009] At least one of the sand cores can be elongated and / or curved, for example in a meandering or spiral shape, and have at least two end sections for forming a through-opening through which a channel in the casting to be produced can be accessed. For this purpose, the end sections of the sand core can be connected to the casting mold or another sand core, for example by means of a clamping connection, an adhesive connection and / or a plug connection.

[0010] It is conceivable to provide two connecting sections which do not form end sections.

[0011] If the casting is used for an electric drive, such a channel in the casting can be provided as a cooling channel, through which a coolant, such as oil, water and / or a coolant containing water, can be conducted.

[0012] Since the casting mold according to the invention has great freedom in designing the structure of the casting, the course of the channels in the casting can be designed by means of a sand core which can be completely surrounded in sections by the light metal melt in the circumferential direction, so that, for example, when the casting is used for an electric drive, the channels designed as cooling channels can be led through locations on the electric drive which are subjected to particularly high thermal loads when used in a motor vehicle. This is necessary, for example, in the stator receiving area of ​​an electric motor.

[0013] The casting mold according to the present invention may be a permanent mold, such as a hard mold, or a sand casting mold.

[0014] In a permanent casting mold, such as a hard mold, the outer mold wall, which forms the outer contour of the casting to be produced, is made of metal, while the inner region of the casting mold, which forms the inner contour of the casting, is formed by a sand core.

[0015] A sand casting mold is a mold made entirely of sand, except for inserts such as cooling iron, and can be used to produce castings in one go.

[0016] The sand casting mould is preferably self-supporting.

[0017] The casting mold according to the invention can be used for all casting methods using sand casting molds or hard molds, for example the so-called Core Package System (CPS) method with tumbling or the so-called rotational casting method.

[0018] If the casting mould according to the invention is used as a permanent mould for carrying out a dynamic casting method, in which the casting mould is moved during the filling process, the speed of movement can be set during the filling process.

[0019] The movement speed may be, for example, the rotation speed of the tilting mold at which it is pivoted about a pivot axis during the filling process.

[0020] This has the advantage of achieving an efficient casting method in which turbulence during the filling process is avoided while filling the mold quickly.

[0021] The use of the casting mold of the present invention is particularly preferred in gravity casting or low pressure casting.

[0022] The method according to the invention for producing a casting made of a light metal alloy is characterized in that at least one sand core arranged in the casting mold is completely surrounded in the circumferential direction at least in sections by a light metal melt, with which the casting mold is filled to form the casting. This makes it possible to produce, for example, curved elongated channels which can themselves have branches, in a manner close to the final contour.

[0023] At least one of the sand cores is advantageously at least partially curved, wherein the ratio of the length of the sand core to the cross-sectional dimension of the sand core is between 5 and 60, preferably between 7.5 and 38, wherein the cross-sectional dimension of the sand core is at least 1.6 mm.

[0024] Since the sand core is curved at least in regions, it is advantageously possible to produce a casting having channels whose geometry cannot be produced using the drilling methods known from the prior art.

[0025] The length of at least one sand core is the distance between a first end section of the sand core, at which the sand core is connected to the mold or another sand core, and a second end section facing away from the first end section, at which the sand core is connected to the mold or another sand core. This means that the length of the sand core corresponds to the length of the channel constructed by the sand core, which is determined by determining the distance from the inlet to the outlet of the channel along the center line of the cross section of the channel.

[0026] When considering the cross section of a sand core, the cross section size of the sand core is the distance between the two points on the cross section of the sand core that are farthest apart.

[0027] If the cross section of the sand core is circular, the cross section size of the sand core is equal to the diameter.

[0028] If the core cross section is elliptical, the core cross section size corresponds to the larger of the two diameters.

[0029] The core cross-sectional dimensions may be constant over its length or may have regions of varying core cross-sectional dimensions. If the core has regions of varying cross-sectional dimensions, the smallest core cross-sectional dimension should be used to form the ratio.

[0030] It is contemplated that the ratio may be formed using the average core cross-sectional dimension over the length of the core.

[0031] The cross section of the sand core can be circular, annular, elliptical, polygonal or trapezoidal. In the region of the construction channel, the cross section of the sand core is preferably circular, elliptical or square with rounded corners.

[0032] The inventors have found that a sand core having a ratio of length to core cross-sectional dimension according to the invention and a core cross-sectional dimension of at least 1.6 mm has sufficient stability to deform only slightly when in contact with a liquid light metal alloy. This has the advantage that a casting mold can be produced with which castings can be produced close to the final contour. In addition, the channels of these castings have channel lengths and shapes that have not been produced to date.

[0033] The cross-sectional dimensions of the sand core are at least 1.6 mm, which results in particularly good cross-sectional stability when in contact with the melt.

[0034] The inventors have also found that such sand cores can be used in a variety of different casting processes, such as the so-called core pack process with flipping, permanent molds and even die casting processes.

[0035] If the ratio of the core length to the cross-sectional dimension of the core is between 5 and 60, cooling channels can be formed in the casting produced using the mold according to the invention, so that particularly uniform cooling can be achieved during the intended use of the casting, in particular when it is used as a housing for an electric drive. This has the advantage that material fatigue caused by temperature change stresses can be greatly reduced.

[0036] If the ratio of the core length to the core cross-sectional dimension is between 7.5 and 38, in addition to particularly uniform cooling, very rapid cooling can be achieved at the same time. For example, temperature peaks that occur when a casting is produced using the casting mold according to the invention for the intended use in an electric drive can be dissipated particularly quickly. This effectively prevents the electric drive from overheating.

[0037] In one embodiment of the present invention, at least one sand core is elongated and preferably has a supporting element, through which the sand core is connected to the casting mold or another sand core, wherein the spacing between adjacent supporting elements in the longitudinal direction of the sand core is between 60 mm and 200 mm, preferably between 90 mm and 150 mm, and particularly preferably between 99 mm and 121 mm.

[0038] By using support elements, for example made of sand, long channels with particularly complex geometries can be formed in the casting. The support elements ensure that the at least one sand core, which is in direct contact with the light metal melt during filling of the casting mold, retains its shape virtually and deforms only slightly under the influence of heat. This advantageously allows castings to be produced with particularly close manufacturing tolerances and close to the final contour.

[0039] If at least one of the sand cores is designed, for example, in regions in a meandering or spiral manner, the supporting elements can prevent the sand core from collapsing during the mold filling.

[0040] If a support element is used, in the contact region of the support element against the at least one sand core, an additional through-hole is respectively formed in the channel formed in the casting, which through-hole can be closed by a plug. By using a support element that supports the at least one sand core and using a closing plug, particularly long channels with complex geometries or curved courses can be advantageously formed in the casting.

[0041] The support element is preferably integrally formed on at least one of the sand cores and is formed from molding sand.

[0042] The inventors have found that when filling the casting mold according to the invention, in particular when the casting mold is used for gravity casting or low-pressure casting, support elements at a spacing of between 60 mm and 200 mm from one another lead to particularly good core stability.

[0043] In pressure casting processes such as high pressure die casting (HPDC), support elements with a spacing of between 99 mm and 121 mm provide particularly good core shape stability despite the high mechanical loads on the sand core during the filling process.

[0044] In the low-pressure casting process with so-called tumbling, the use of supporting elements at a distance of between 90 mm and 150 mm from one another has proven to be effective.

[0045] In summary, the casting mold according to the invention is advantageously suitable for use in a variety of different casting methods.

[0046] In another embodiment of the present invention, at least one sand core has at least one connecting section, which is constructed to form a shape-fitting, force-fitting and / or material-fitting connection with a casting mold or another sand core, wherein an orientation bevel and / or an exhaust channel is preferably provided in the transition area from at least one connecting section to the casting mold or another sand core.

[0047] It is understood that at least one connecting section may be designed as a supporting element or may play a supporting role.

[0048] The orientation bevel allows particularly precise positioning of the at least one sand core, while the exhaust duct ensures that air or so-called core gas can escape from the at least one sand core which is completely surrounded in sections by the light metal. This has the advantage that castings close to the net shape can be produced with no defects in casting quality.

[0049] The size of the exhaust channel is between 0.05 and 1.5 mm.

[0050] It is conceivable that at least one sand core has a plurality of connecting sections which are intended to form a shape-fitting, force-fitting and / or material-fitting connection with the casting mold or another sand core, wherein an orientation bevel and / or an exhaust channel are preferably provided in the transition region between the connecting section and the casting mold or another sand core.

[0051] In particular, at least one sand core may have two connecting sections, which are arranged at both ends of the at least one sand core and may be formed in an elongated form, thereby creating a channel with an inlet and an outlet for a medium such as a coolant in a casting produced using the casting mold of the invention.

[0052] If the sand core has only one connecting section, blind hole-like channels can be formed in the casting produced using the casting mold according to the invention.

[0053] Advantageously, at least one of the sand cores is three-dimensionally printed and preferably has at least one cavity or comprises an area in which no binder is introduced. The binder is formed in the form of an adhesive, which bonds a plurality of sand grains to one another to form the at least one sand core. By means of the three-dimensional printing technique, the sand cores can be produced layer by layer, so that sand cores with complex geometries, such as undercuts, can be produced, which cannot be produced by a core shooter. The ejected sand core also requires a demoulding chamfer for removal from the tool of the core shooter. Thus, using the three-dimensional printing technique, in particular sand cores with walls that are perpendicular to one another can be produced.

[0054] In addition, 3D printing technology can also be used to produce sand cores without demoulding chamfers, i.e. without demoulding chamfers.

[0055] Typically, the binder content in 3D printed sand cores is many times higher than in injected sand cores.

[0056] Since the binder in the sand core decomposes on contact with the light metal melt, forming so-called core gas, binder-free areas are required or at least one cavity is required into which the core gas can flow. It is advantageous to ensure that no defects caused by core gas are formed in the casting to be produced.

[0057] In the case where the 3D printed core has at least one cavity, it is conceivable that one side of the cavity is open, with the opening being covered by the adjacent casting sand core.

[0058] It is also conceivable that at least one cavity can be vented via a venting channel, ie core gas formed within the casting mold can be discharged via the cavity to the outside of the casting mold.

[0059] It will be appreciated that an extraction device may be provided by which core gas is extracted from the mould.

[0060] In one embodiment of the present invention, the casting mold includes another 3D-printed sand core having a space for receiving a cooling element.

[0061] By using cooling elements made of metal, so-called cooling irons, the solidification of the light metal melt can be positively influenced in the region of the cooling element, i.e. a fine-grained casting structure is formed in the region around the cooling element, which has particularly good mechanical properties. In addition, in particular in the case of aluminum-based melts, the formation of pores in the casting to be produced in the region of the cooling element due to hydrogen outgassing is prevented. When a liquid medium, such as a coolant, passes through, these so-called hydrogen pores can lead to leaks, in particular in the case of thin-walled channels.

[0062] When using the casting mold according to the invention, the above-mentioned properties can be achieved by cooling at a cooling rate of 10 to 15 Kelvin per second in the region of the casting to be produced at a distance of 3 to 5 mm from the cooling element.

[0063] The inventors have recognized that the above cooling rates of 10 to 15 Kelvin per second and the above distances from the cooling element are sufficient to achieve the desired casting properties. It has also been recognized that higher cooling rates are not necessary but rather hindering, as they lead to the formation of cavities.

[0064] In another embodiment of the invention, the casting mold comprises an additional sand core and / or a permanent mold insert, wherein the additional sand core is formed as a motor core and the permanent mold insert is formed as a motor permanent mold insert and is used to form a receiving space in the casting, into which the stator and the rotor of the motor can be introduced.

[0065] A permanent mold insert is an insert that can be used multiple times and, after a casting has been produced, can be reinserted into the mold to produce another casting. For example, such permanent mold inserts can be used in hard die casting or other casting processes that use permanent molds.

[0066] The motor core or the permanent motor mold insert can in particular be rotationally symmetrical, for example, can lie in a casting mold so that, for example in a gravity casting process, the molten metal does not rise longitudinally thereon but flows circumferentially around the motor core or the permanent motor mold insert.

[0067] The inventors have found that in order to obtain a non-porous wall in the casting which defines a receiving space into which a cooling channel is introduced, it is not necessary for the melt to rise in the longitudinal direction on the motor core or on the permanent casting insert of the motor.

[0068] The casting mold according to the invention is suitable for producing a housing of an electric drive of a motor vehicle, the electric motor of which can be designed as an inner rotor motor or an outer rotor motor.

[0069] The motor core is preferably designed as a multi-component type, wherein each motor core component has a demoulding chamfer that extends circumferentially on the outer sleeve surface of the motor core in the longitudinal direction of the motor core, and / or the motor permanent mold insert has a demoulding chamfer that extends circumferentially on the outer sleeve surface in the longitudinal direction of the motor permanent mold insert.

[0070] The draft angle is necessary for injection molded cores so that they can be removed from a conventional two-piece core shooting tool. Depending on the complexity of the core, the draft angle for injection molded cores ranges from 0.5 to 2 degrees.

[0071] The motor core is preferably composed of two parts and is rotationally symmetrical, for example conical or cylindrical, wherein each motor core part is rotationally symmetrical.

[0072] If the motor core consists of two parts, the two motor core parts can be arranged one after the other in the longitudinal direction of the core and can abut against each other at the contact surface to form a flush transition, thereby forming the motor core. The two motor core parts can have the same size in the longitudinal direction of the motor core. It is conceivable that the two motor core parts have different sizes, especially in the longitudinal direction of the motor core.

[0073] Each demoulding slope of the motor core component can be descended or ascended from the outer end of the motor core component to the contact plane.

[0074] A motor core is achieved which has two demoulding chamfers, for example, each of which extends over half of the entire motor core. It is advantageous to construct demoulding chamfers in the casting produced using the casting mold of the invention, which results in the accommodation space for the stator and rotor deviating from a cylindrical shape and being only half that of a one-piece core. This significantly reduces the amount of machining work required to create a cylindrical accommodation space for the stator and rotor.

[0075] The same applies to permanent motor mold inserts, however, they can be designed as one piece or in multiple parts like the motor core.

[0076] By using a casting mold according to the invention with such an electric machine core or a permanent mold insert for an electric machine, a casting can be produced that is close to the final contour.

[0077] It will be appreciated that the amount of machining can be further reduced by using a three, four or five part motor core or similar permanent mold insert for the motor.

[0078] It is conceivable that a jacket surface section of the motor core or of the permanent motor mold insert is formed by at least one cooling element.

[0079] In one embodiment of the present invention, the mold is designed so that the normal line of the melt front of the light metal melt is arranged obliquely to the normal line of the mold region where the light metal melt contacts the mold, wherein the mold is filled with the light metal melt against the direction of gravity.

[0080] In gravity casting or low pressure casting, when using the casting mold according to the present invention (which can be designed as a permanent mold, such as a hard mold or a sand casting mold), the melt front can rise in the casting mold against the direction of gravity, that is, the normal line of the melt front is parallel and arranged against the direction of gravity.

[0081] When the mold is filled with the melt, the mold air is replaced by the melt, and the mold cavity forming the casting to be made is filled with the melt.

[0082] Since the normal line of the melt front is oblique to the normal line of the casting mold area where the melt contacts the casting mold, this advantageously forms an inclined surface extending in a direction opposite to the gravity direction, and the mold air discharged from the casting mold can be guided out along the inclined surface. In this way, casting defects caused by mold air entrainment can be effectively prevented.

[0083] It will be appreciated that the orientation of the normal to the melt front and the normal to a region of the mould relative to each other can be altered by changing the orientation of the mould during filling in the earth's gravitational field. This is not the only way, but is essential to the design of the so-called spin casting process.

[0084] Such a mold design is particularly suitable for providing mold regions for reinforcing or cooling ribs in the cast component to be produced, ie elongated, narrow grooves or cylindrical projections for receiving screws for fastening additional components to the component produced from the cast component.

[0085] In another embodiment of the invention, the casting mold has an insert element, which is designed to influence the flow characteristics of the light metal melt flowing into the casting mold, wherein the insert element is especially designed as a casting filter or a casting filter cascade. The casting filter can be sponge-shaped and made of ceramic. The porosity of the casting filter can be between 10 and 60 ppi (pores per inch), preferably between 25 and 55 ppi, and particularly preferably between 40 ppi and 50 ppi.

[0086] By using a casting filter or a casting filter cascade, a homogenization of the light metal melt flow during the filling of the casting mold can be achieved, ie turbulence which could lead to casting defects such as oxide inclusions can be effectively prevented.

[0087] In one embodiment of the invention, the casting mold has an insert element which is to remain in the casting produced by the casting mold and is preferably designed as a component of an electric drive for which the casting can be used.

[0088] Such a component could be, for example, a heating coil that is cast into the wall of the casting and can be used for preheating when the casting is used in electric vehicles. Such a component could also be a reinforcement element, for example for sand cores or bearing seats, which could achieve higher mechanical stability and / or significantly improved tribological properties.

[0089] The insertion element can be designed as a sensor.

[0090] The casting mold advantageously has an insert element formed by a material other than the molding sand, which is arranged to be taken out from the casting produced with the mold. For example, such an insert element can be used to form a particularly small channel with a cross section less than 6 mm, preferably between 1 and 4 mm.

[0091] The insert element may be hollow so that it can be completely removed from the casting.

[0092] In one embodiment of the invention, the casting mold has a region containing a plurality of further sand cores, wherein the further sand cores are provided to form receiving housings for power electronics and / or transmission elements of an electric drive when the casting is used for an electric drive of a motor vehicle.

[0093] In an electric drive, power electronic components include current transformers or inverters, etc. A casting mold can be advantageously produced, from which, for example, a housing for the electric drive can be produced, and further component accommodation spaces are integrally formed on the housing. Advantageously, no mounting step is required to connect such component accommodation spaces to the housing.

[0094] The inventors have overcome the technical prejudice that individual components of an electric drive device must be connected to a housing flange and have found that it is very advantageous to introduce them into a component receiving space formed integrally with the housing.

[0095] In another embodiment of the invention, the casting mold has an area containing a plurality of additional sand cores, wherein the plurality of additional sand cores are used to construct cooling channels through which a cooling fluid can flow in a controlled manner when the casting is used for an electric motor of a motor vehicle. Such an area can be integrated into the housing of the electric motor as part of the casting in order to construct a temperature management system for controlling a cooling or heating system. This system, for example, also makes it possible in combination with a heat pump to utilize the waste heat generated by the electric motor and power electronics when required, for example to heat the vehicle or to preheat or heat the drive battery. By introducing cooling channels into the casting, the coolant can flow through these cooling channels under the control of a control device, so that the cooling channels do not need to be rearranged when assembling the electric motor. This avoids possible defects and significantly reduces the work of assembling the electric motor, while also reducing the length of the pipelines and the associated weight.

[0096] In one embodiment of the invention, a cavity is formed in at least one side section of the casting mold, which cavity forms an additional feed opening, wherein the cavity is fluidically connected to the mold cavity forming the casting via a through-channel. In so-called gravity casting for solidifying light metal melts, the casting mold is filled via this feed opening, which is usually located above the casting and whose feed neck is connected to the casting only on the upper side of the casting. Although this allows the entire casting to be fed, large casting areas, such as thin walls with a wall thickness of between 1 and 4 mm, cannot be fed sufficiently due to the fluid connection to the feed opening via these walls, making these casting areas particularly susceptible to cavities.

[0097] By connecting an additional feed opening to one side of the casting, in particular castings with large dimensions and small regional wall thicknesses can be produced without defects, in particular without cavities. It is understood that the additional feed opening is fluidically connected to the feed opening above the casting, which serves as the main feed opening, that is, the cavity in the casting mold forming the main feed opening and the cavity forming the additional feed opening are connected to each other via a through-channel.

[0098] Particularly in the region of the receiving spaces for stators and rotors of electric drives, the cast region can be filled in below the thin walls which can define cooling channels introduced therein. This prevents the formation of cavities which would render the cast part unusable.

[0099] The casting mould also advantageously comprises a venting device which defines a venting channel and forms an inner casting mould wall section. The inner casting mould wall section defines a cavity which is filled with the melt to form the casting when the mould is filled.

[0100] The exhaust device is particularly advantageous for permanent molds. The exhaust device may include an exhaust nozzle, particularly arranged at the end of the exhaust channel facing the casting mold cavity. For example, the exhaust nozzle may have an exhaust slit.

[0101] For example, particularly large venting channels can be created, the casting mold can be adequately vented even during rapid filling, and since the venting device forms a mold wall segment, the casting geometry to be produced is not deviated from. BRIEF DESCRIPTION OF THE DRAWINGS

[0102] The present invention will be explained in more detail below through embodiments and drawings related to the embodiments. In the drawings:

[0103] FIG. 1 shows a first embodiment of a casting mold for manufacturing a housing of an electric drive device for a vehicle according to the present invention.

[0104] FIG. 2 shows another embodiment of a casting mold for manufacturing a housing of an electric drive device for a vehicle according to the present invention.

[0105] Figure 3The invention shows details of an embodiment of a casting mold for producing a housing of an electric vehicle drive.

[0106] Figure 4 Another embodiment of the casting mold for manufacturing a housing of a vehicle electric drive device according to the present invention is shown.

[0107] FIG. 5 shows an embodiment of a casting mold for manufacturing a housing of an electric drive device for a vehicle according to the present invention,

[0108] FIG. 6 shows a particular embodiment of a casting mold according to the invention for producing a housing of an electric vehicle drive. DETAILED DESCRIPTION

[0109] exist Figure 1a In perspective top view, Figure 1b China-Israel Figure 1a The sand casting mold 1 shown in a section through the section AA has a basic sand core 2, which includes a curved sand core 3 with an elliptical cross section 4. In the present exemplary embodiment, the sand core 3 is arranged in the sand casting mold 1 in such a way that the section 5 arranged between two connecting sections 6, 7, which forms a channel, can be completely surrounded by a light metal melt (dashed spiral arrow 8), with which the sand casting mold 1 is filled to produce a casting. Each connecting section 6, 7 is connected to the sand casting mold 1 by a plug connection, wherein, for example, a channel inlet can be formed in the casting at the transition 9 between the connecting section 6 and the basic sand core 2.

[0110] The basic sand core 2 also has a filling channel 10, through which the light metal melt can flow into the sand casting mold 1. It is conceivable to arrange a casting filter (not shown in FIG. 1) in the filling channel 10 or in the region of the filling channel 10.

[0111] In the present exemplary embodiment, the channel to be produced in the casting is formed by a curved sand core 3, wherein the cavity forming the channel wall is delimited in particular by the motor core 11. Figure 1b The middle section shows a cross section of the motor core. Figure 1a The motor core 11 is essentially cylindrical, with its outer surface section 12 being formed by a cooling element 13 made of cast iron. The motor core 11 forms a receiving space in the casting, in which in particular the stator and the rotor of the electric drive can be accommodated.

[0112] Figure 1c The sand core 3 shown in the perspective top view and Figure 1a and Figure 1b The difference between the sand core shown in FIG. 3 and FIG. 4 is that the sand core 3 has a single connecting section 7 and a Figure 1c There is no free end with a reference numeral in the figure.

[0113] Through Figure 1c The sand core 3 shown enables blind-hole-like passages to be introduced into the casting produced with the casting mold 1 .

[0114] Reference is now made to FIG. 2 , in which identical or equivalent components are denoted by the same reference numerals as in FIG. 1 , with the letter a being added in each case after the corresponding reference numeral.

[0115] exist Figure 2a In perspective, Figure 2b In the top view and Figure 2c China-Israel Figure 2b The sand casting mold 1a shown in the sectional side view of the AA section is different from that shown in Figure 1 in that the horseshoe-shaped sand core 3a in the top view has an additional supporting element 14, which is arranged between the two connecting sections 6a and 7a. The supporting element 14 is made of molding sand and is integrally formed on the sand core 3a.

[0116] In the present embodiment, the horseshoe-shaped sand core 3a in the top view is produced by 3D printing and has a cavity 15 and a venting channel 16, through which the so-called core gas from the sand core can be discharged from the sand casting mold 1a when the sand casting mold is filled with a light metal melt. This is particularly advantageous for sand cores with a high binder content, because when the mold cavity is filled with a light metal melt, these sand cores are completely surrounded by the light metal melt in sections.

[0117] Reference now Figure 3 , Figure 3 The same or equivalent components are represented by the same reference numerals as in Figures 1 and 2, and the letter b is added to the corresponding reference numerals.

[0118] A portion of the sand mold 1b schematically shown in cross section comprises a deep and narrow recess 17 in a side part of the sand mold 1b, which is designed to form a reinforcing rib of a casting that can be produced using the sand mold. A normal 18 of an upper sand mold wall section 19 in the region of the recess 17 is arranged obliquely to a normal 20 of a melt front 21 of the light metal melt, which in the present exemplary embodiment rises against the direction 22 of action of gravity in the sand mold 1b for filling of the sand mold.

[0119] The sand mold wall section 19 forms an inclined surface, and the mold air 23 squeezed out when the melt front 21 rises in the sand mold 1b can slide along the arrow 24. The advantage of this is that mold air will not be trapped in the groove, thereby effectively preventing the casting from being scrapped due to casting defects.

[0120] It is conceivable that the exhaust air duct is led through the sand casting mold wall section so that the mold air is led directly out of the sand casting mold 1 b.

[0121] Reference now Figure 4 ,exist Figure 4 In the drawings, the same or equivalent parts are used as in FIGS. 1 to Figure 3 The same reference numerals are used, with the letter c being added after the corresponding reference numerals.

[0122] exist Figure 4 In the sand casting mold 1c shown in a sectioned perspective view in FIG, the side wall core 25 is 3D printed and has a through channel 26 in which a cooling element 27 made of cast iron is inserted. Since the side wall core 25 is 3D printed, the through channel can be configured so that the cooling element 27 enters the side wall core 25 from outside the sand casting mold 1c and is retained in a force-fitting manner.

[0123] Referring now to FIG. 5 , in FIG. 5 , the same or equivalent components are used as in FIGS. 1 to 5 . Figure 4 The same reference numerals are used with the letter d added after the corresponding reference numerals.

[0124] exist Figure 5a In the sand casting mold 1d shown in a perspective top view, the motor core 11d consisting of two parts is lying in the sand casting mold 1d. Lying means that the light metal melt filling the sand casting mold 1d flows in the circumferential direction, for example, against the direction of gravity 22d, and surrounds the basically cylindrical motor core 11d, rather than flowing longitudinally along the cylindrical axis 28.

[0125] The two motor core components 29 and 30 are connected to each other by plug connection and abut against each other in the contact plane 31 to form the motor core 11d. Figure 5b The motor core 11d shown in the perspective detail view includes a groove 32 for accommodating the Figure 1b The cooling element is marked with reference numeral 13.

[0126] Although it is conceivable that the motor core is 3D printed, in this embodiment it is designed as a molded sand core.

[0127] Each motor core component 29 , 30 has a demoulding chamfer 33 , which extends circumferentially on an outer jacket surface 35 in a circumferential direction 34 and descends in the direction of arrow 36 .

[0128] Referring now to FIG. 6 , the same or equivalent components in FIG. 6 are denoted by the same reference numerals as in FIGS. 1 to 5 , with the letter e added to the corresponding reference numerals, respectively.

[0129] exist Figure 6a In perspective, Figure 6b In the top view and Figure 6c China-Israel Figure 6bThe sand casting mold 1e shown in the cross-sectional side view at section AA of FIG. 1 comprises a cavity 37 constituting the main feed inlet of a casting that can be produced using the sand casting mold 1e and arranged above the casting when the casting solidifies. A fluid connection is provided between the cavity 37 and the mold cavity (not shown in FIG. 6 ) forming the casting by a through-channel 38.

[0130] The multi-part side wall core 39 of the sand casting mold 1e contains a cavity 40 which forms an additional feed opening which is connected laterally to the produced casting and is fluidically connected to the cavity 37 forming the main feed opening via a plurality of through-channels 41 .

[0131] The fluid connection between the cavity 40 forming the additional feed opening and the cavity of the mold forming the cast part is ensured by a through-channel 42. For the sake of clarity, not all through-channels 42 are provided with reference numerals.

[0132] It is conceivable that the casting mold (1-1e) is provided for producing a housing of an electric drive and has a region with a plurality of sand cores for forming a receiving housing for power electronics and / or a transmission element of the electric drive.

[0133] Furthermore, the casting mold (1-1e) can also have a plurality of additional sand cores which, when the casting is used for an electric motor of a motor vehicle, are used to form cooling channels through which the coolant flows in a controlled manner.

[0134] It is also conceivable that the casting mold (1-1e) can have an insert element which is designed to remain in the casting produced with the casting mold. For example, it can be a component of an electric drive produced with the casting.

[0135] It is to be understood that all possible combinations of the features shown in Figures 1 to 6 are contemplated. For example, the sand casting mold shown in Figure 6 may have Figure 3 The groove 17 is shown.

[0136] It is also understood that the casting mold according to the present invention can be a permanent casting mold. For example, the permanent casting mold can be a hard mold or a die casting mold with a sand core inserted.

Claims

1. A casting mold (1-1e) for producing a casting made of a light metal alloy, in particular a housing for an electric drive of a motor vehicle, It is characterized in that The casting mold (1-1e) has at least one sand core (3; 3a; 3c), which is designed and arranged in the casting mold (1-1e) so that the at least one sand core (3; 3a; 3c) is completely surrounded by a light metal melt in the circumferential direction at least in sections, and the casting mold is filled with the light metal melt to form a casting.

2. The casting mold according to claim 1, characterized in that At least one of the sand cores (3; 3a; 3c) is at least partially curved, wherein the ratio of the length of the sand core (3; 3a; 3c) to the cross-sectional dimension of the sand core is between 5 and 60, preferably between 7.5 and 38, and wherein the cross-sectional dimension of the sand core is at least 1.6 mm.

3. The casting mold according to claim 1 or 2, characterized in that: At least one of the sand cores (3; 3a; 3c) is elongated and preferably has a supporting element (14), via which the sand core (3; 3a; 3c) is connected to the casting mold (1-1e) or another sand core, wherein the spacing between adjacent supporting elements (14) in the longitudinal direction of the sand core is between 60 mm and 200 mm, preferably between 90 mm and 150 mm, and particularly preferably between 99 mm and 121 mm.

4. The casting mold according to any one of claims 1 to 3, characterized in that At least one sand core (3; 3a; 3c) has at least one connecting section (6, 7; 6a, 7a) which is designed to form a shape-fitting, force-fitting and / or material-fitting connection with a casting mold (1-1e) or another sand core, wherein an orientation bevel and / or an exhaust channel (16) is preferably provided in the region of a transition section (9; 9c) from at least one connecting section to the casting mold (1-1e) or another sand core.

5. The casting mold according to any one of claims 1 to 4, characterized in that At least one of the sand cores (3; 3a; 3c) is three-dimensionally printed and preferably has at least one cavity (15) or includes an area in which no adhesive is introduced.

6. The casting mold according to any one of claims 1 to 5, characterized in that The casting mold further comprises a further sand core (25) which is 3D printed and has a space (26) designed to accommodate a cooling element (27).

7. The casting mold according to any one of claims 1 to 6, characterized in that The casting mold (1-1e) comprises an additional sand core (11; 11d) and / or a permanent mold insert, wherein the additional sand core (11; 11d) is designed as a motor core and the permanent mold insert is designed as a motor permanent mold insert, which is configured to construct a receiving space in the casting, into which the stator and rotor of the motor can be introduced.

8. The casting mold according to claim 7, characterized in that The motor core (11; 11a) is of multi-piece design, wherein each motor core component (29, 30) has a demoulding chamfer (33) which extends circumferentially on an outer sleeve surface (35) in the longitudinal direction of the motor core, and / or the motor permanent mold insert has a demoulding chamfer which extends circumferentially on an outer sleeve surface in the longitudinal direction of the motor permanent mold insert.

9. The casting mold according to any one of claims 1 to 8, characterized in that The casting mold (1-1e) is designed so that a normal line (20) of a melt front (21) of a light metal melt is arranged obliquely to a normal line (18) of a casting mold region (19) where the light metal melt and the casting mold are in contact, wherein the casting mold (1-1e) is filled with the light metal melt in the opposite direction of the action of gravity (22).

10. The casting mold according to any one of claims 1 to 9, characterized in that The casting mold (1-1e) has an insert element which is configured to influence the flow characteristics of a light metal melt flowing into the casting mold, wherein the insert element is designed in particular as a casting filter or a casting filter cascade.

11. The casting mold according to any one of claims 1 to 10, characterized in that The casting mold (1-1e) has an insert element which is intended to remain in a casting produced by the casting mold and is preferably formed as a component of the electric drive, and the casting can be used for the electric drive.

12. The casting mold according to any one of claims 1 to 11, characterized in that The casting mold (1-1e) has an insert element made of a material other than molding sand, which is provided for removal from a casting produced by the casting mold.

13. The casting mold according to any one of claims 1 to 12, It is characterized in that The casting mold (1-1e) has a region containing a plurality of further sand cores, wherein the further sand cores are provided for forming receiving housings for power electronics and / or transmission elements of an electric drive when the casting is used for an electric drive of a motor vehicle.

14. The casting mold according to any one of claims 1 to 13, characterized in that The casting mold (1-1e) has a region containing a plurality of additional sand cores, wherein the plurality of additional sand cores are used to form cooling channels through which a cooling fluid can flow in a controlled manner when the casting is used for an electric motor of a motor vehicle.

15. The casting mold according to any one of claims 1 to 14, It is characterized in that A cavity (40) is formed in at least one side portion (39) of the casting mold (1-1e), the cavity forming an additional feed opening, wherein the cavity (40) is fluidically connected to the mold cavity forming the casting via a through-channel (42).

16. A method for producing a casting made of a light metal alloy, in particular a housing for an electric drive of a motor vehicle, It is characterized in that At least one sand core (3; 3a; 3c) arranged in the casting mold is completely surrounded in the circumferential direction at least in sections by a light metal melt, with which the casting mold is filled to form a casting.

17. The method according to claim 16, characterized in that A sectionally curved channel is formed in the casting by a sand core (3; 3a; 3c) which is completely surrounded in sections by the light metal melt in the circumferential direction.

18. The method according to claim 16 or 17, characterized in that The light metal melt is cooled at a distance of 3 to 5 mm from a cooling element (13; 27) introduced into the casting mold (1-1e), with a cooling rate of at least 10 Kelvin per second, preferably at least 13 Kelvin per second, particularly preferably at least 15 Kelvin per second.

19. The method according to any one of claims 16 to 18, It is characterized in that The speed of movement of the permanent mold during the filling process can be adjusted.

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