MOLD FOR THE PRODUCTION OF A CASTING MADE FROM A LIGHT METAL ALLOY

Description

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

[0002] Molds, sand cores and methods for the production of light metal castings are known, for example, from EP 3 600 718 B1, EP 3 810 357 B1, EP 2 945 760 B1, CN 105 305 704 A, DE 10 2013 101942 B3, DE 10 2018 221826 A1 and WO 2021 / 157242 A1.

[0003] It is also known from the prior art that cooling channels, i.e., channels in a casting that guide a cooling medium which may include water, oil and / or a cooling fluid containing water, are drilled into the casting. Due to the manufacturing process, such channels are always straight, which unfortunately leaves no design freedom.

[0004] The invention is based on the objective of creating a casting mold of the type mentioned above, through which a casting made of a light metal alloy can be produced, into which channels have already been incorporated.

[0005] Furthermore, the invention is based on the objective of creating a mold for the production of a casting which allows for a great deal of design freedom.

[0006] The subject matter of the invention is defined by the independent claims; the dependent claims describe preferred embodiments. 1

[0007] According to the invention, the problem is solved by the fact that the mold has at least one sand core which is designed and arranged in the mold in such a way that the at least one sand core can be completely surrounded, at least partially, in a circumferential direction by a light metal melt with which the mold is filled to form the casting.

[0008] If the at least one sand core is completely surrounded in the circumferential direction by the light metal melt in sections, a channel is formed in the casting, the channel walls of which are formed by solidification of the light metal melt surrounding the at least one sand core, while a cavity is formed by the at least one sand core, which can be removed from the casting by mechanical or thermal treatment.

[0009] The at least one sand core can be elongated and / or curved, for example meandering or helical, and have at least two end sections that form a through-opening, providing access to the channel in the casting to be produced. For this purpose, the end sections of the sand core can be connected to the mold or another sand core, for example by a clamping, adhesive, and / or plug-in connection.

[0010] It is conceivable that two connecting sections are provided that do not form end sections.

[0011] A channel designed in this way in the casting can be provided as a cooling channel when the casting is used for an electric drive, through which a cooling fluid such as oil, water and / or a cooling fluid containing water is passed.

[0012] Because a casting mold according to the invention allows for a great deal of design freedom in the casting, the course of the channel in the casting can be designed such that, for example, when the casting is used for an electric drive, a channel designed as a cooling channel is routed past those points where a particularly high thermal load occurs when the electric drive is used in a motor vehicle. This is necessary, for example, in the area of ​​a stator mount of an electric motor.

[0013] A casting mold according to the invention can be designed as a permanent mold, for example as a die, or as a sand casting mold.

[0014] In a permanent mold such as a die, outer mold walls made of metal form the outer contours of a casting to be produced, while inner mold areas made of sand cores form the inner contours.

[0015] A sand casting mold is a mold that, apart from insert elements such as cooling irons, is made entirely of sand and can only be used once to produce a casting.

[0016] Preferably, a sand casting mold is self-supporting.

[0017] A mold according to the invention is usable for all casting processes in which a sand casting mold or a die is used, for example the so-called CPS (Core Package System) process with rollover or the so-called Rotacast process. If a mold according to the invention is used as a permanent mold for carrying out a dynamic casting process in which the mold is moved during mold filling, a movement speed during mold filling can be adjusted.

[0018] A movement speed can be, for example, a pivoting speed at which a tilting mold is rotated around a pivoting axis during mold filling. This advantageously creates an efficient casting process in which particularly fast mold filling is possible while simultaneously avoiding turbulence during the filling process.

[0019] The use of the casting mold according to the invention in gravity casting or low-pressure casting is particularly preferred.

[0020] A 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 a mold is completely surrounded, at least partially in a circumferential direction, by a molten light metal with which the mold is filled to form the casting. This provides a casting method with which, for example, curved, elongated channels, which in turn may have branches, can be produced close to their original shape.

[0021] The at least one sand core is curved at least in some areas, wherein the ratio of the length of the sand core to the cross-sectional area of ​​the sand core is between 5 and 60, preferably between 7.5 and 38, wherein the cross-sectional area of ​​the sand core is at least 1.6 mm.

[0022] Because the sand core is curved at least in some areas, it is advantageous to produce a casting with a channel whose channel geometry cannot be produced using a drilling method known from the prior art.

[0023] The length of the at least one sand core is the distance from a first end section of the sand core, where the sand core is connected to the mold or to another sand core, to a second end section opposite the first end section, where the sand core is also connected to the mold or to another sand core. This means that the length of the sand core corresponds to the length of the channel it forms, the length being determined by measuring the distance from an inlet opening to an outlet opening of the channel along a profile centerline of the channel.

[0024] A sand core cross-sectional area dimension, when considering a sand core cross-section, is the distance between two points of the sand core cross-section that are furthest apart.

[0025] If the sand core has a circular cross-sectional area, the cross-sectional area of ​​the sand core corresponds to the diameter.

[0026] If the sand core has an oval cross-sectional area, the sand core cross-sectional area corresponds to the larger of the two diameters.

[0027] The cross-sectional area of ​​the sand core can be constant along its length or it can have sections with different cross-sectional areas. If the sand core has areas with different cross-sectional areas, the smallest cross-sectional area should be used to calculate the ratio.

[0028] It is conceivable that a sand core cross-sectional area averaged over the length of the sand core is used to calculate the ratio.

[0029] A sand core cross-section can be round, circular, oval, polygonal, or trapezoidal. Preferably, the sand core cross-section in the area forming the channel is round, oval, or rectangular with rounded corners.

[0030] The inventors have found that a sand core exhibiting a length-to-cross-sectional area ratio according to the invention, with a sand core cross-sectional area of ​​at least 1.6 mm, is sufficiently stable to deform only minimally upon contact with a liquid light metal alloy. Advantageously, this creates a mold with which near-net-shape castings can be produced. Furthermore, these castings feature a channel with a length and shape that was previously unattainable.

[0031] A sand core cross-sectional area of ​​at least 1.6 mm ensures particularly good cross-sectional stability when in contact with the melt.

[0032] The inventors have also found that such a sand core can be used with several different casting processes, for example for use in the so-called core pack process with rollover, in die casting or even in pressure die casting.

[0033] If the ratio of the sand core length to the sand core cross-sectional area is between 5 and 60, a cooling channel can be created in a casting produced with a mold according to the invention. This enables particularly homogeneous cooling of the casting during its intended use, especially as a housing for an electric drive. Advantageously, material fatigue caused by temperature cycling can be significantly reduced.

[0034] If the ratio of the sand core length to the sand core cross-sectional area is between 7.5 and 38, very rapid cooling can be achieved alongside particularly homogeneous cooling. Temperature peaks, which occur, for example, during the intended use of a casting produced with a mold according to the invention in an electric drive, can be reduced particularly quickly. Overheating of the electric drive can thus be advantageously prevented.

[0035] In one embodiment of the invention, the at least one sand core is elongated and preferably has support elements by which the sand core is connected to the mold or another sand core, wherein support elements adjacent in a longitudinal direction of the sand core are spaced between 60 mm and 200 mm apart, preferably between 90 mm and 150 mm, and particularly preferably between 99 mm and 121 mm.

[0036] By using support elements, which can be made of sand, for example, a geometrically complex and long channel can be produced in the casting. These support elements ensure that the at least one sand core, which is in direct contact with a molten light metal when the mold is filled, retains its shape almost perfectly and deforms only minimally under heat. This advantageously allows for the production of a near-net-shape casting with particularly tight manufacturing tolerances.

[0037] If, for example, the at least one sand core is shaped in a meandering or helical form in some areas, the support elements can prevent the sand cores from collapsing during mold filling.

[0038] If support elements are used, an additional through-opening is formed in contact areas where the support elements abut the at least one sand core, leading into a channel depicted in the casting. This through-opening can be closed with a plug. Advantageously, by using the support elements that support the at least one sand core and by using closing plugs, a particularly long channel with a complex geometry or curved path can be produced in the casting.

[0039] The support elements are preferably molded in one piece onto the at least one sand core and are made of molding sand.

[0040] The inventors have found that support elements spaced between 60 mm and 200 mm apart result in particularly good core shape stability when filling a casting mold according to the invention, especially when using the casting mold in gravity or low-pressure casting.

[0041] In a high-pressure die casting process (HPDC), support elements spaced between 99 mm and 121 mm apart offer particularly good core shape stability despite high mechanical stress on the sand cores when the mold is filled.

[0042] In low-pressure casting processes with so-called rollover, it has proven effective to use support elements spaced between 90 mm and 150 mm apart.

[0043] Overall, a casting mold according to the invention is advantageously suitable for use with a variety of different casting processes.

[0044] In a further embodiment of the invention, the at least one sand core has at least one connecting section which is designed to form a positive-locking, force-locking and / or material-locking connection with the mold or another sand core, wherein, in the area of ​​a transition from the at least one connecting section to the mold or the other sand core, alignment ramps and / or venting channels are preferably provided.

[0045] It is understood that at least one connecting section can be designed as a support element or can act as such.

[0046] The angled design allows for particularly precise positioning of the at least one sand core, while the venting channels ensure that air or so-called core gas can escape from the at least one sand core, which is partially or completely surrounded by a light metal. This allows for the advantageous production of a near-net-shape casting while maintaining flawless casting quality.

[0047] The size of the vent channels is between 0.05 and 1.5 mm.

[0048] It is conceivable that the at least one sand core has several connection sections which are designed to form a positive, force-fit and / or material-fit connection with the mold or another sand core, wherein alignment ramps and / or venting channels are preferably provided in the area of ​​a transition of the connection sections to the mold or the other sand core.

[0049] In particular, the at least one sand core can have two connecting sections arranged at two ends of the at least one sand core, which can be elongated. This allows, for example, a channel with an inlet opening and an outlet opening for a medium such as a coolant to be created in a casting produced with the mold according to the invention.

[0050] If the sand core has exactly one connecting section, a blind-hole-like channel can be created in a casting produced with the mold according to the invention.

[0051] Advantageously, the at least one sand core is 3D-printed and preferably has at least one cavity or includes areas into which no binder is introduced. The binder is in the form of an adhesive and causes a multitude of sand grains to adhere to one another to form the at least one sand core. 3D printing, in which a sand core is produced layer by layer, makes it possible to produce sand cores with complex geometries, such as undercuts, which cannot be produced with core shooting machines. Furthermore, core-shot sand cores require a draft angle for demolding from a core shooting machine tool. Therefore, sand cores with mutually perpendicular walls can be produced particularly well by 3D printing.

[0052] Furthermore, sand cores can be produced by 3D printing that do not have a draft angle, i.e., are draft angle-free.

[0053] Typically, the binder content in a 3D-printed core is many times higher than in a shot-blown core.

[0054] Because a binder in a sand core decomposes upon contact with a molten light metal, forming so-called core gas, binder-free areas or at least a cavity are required into which the core gas can flow. This advantageously ensures that defects in the casting, caused by core gas, do not form in the first place.

[0055] In the case of a 3D-printed core with at least one cavity, it is conceivable that this cavity is open on one side and that an opening is covered by an adjacent sand core of the casting mold.

[0056] Furthermore, it is conceivable that at least one cavity can be vented through a venting channel, meaning that core gas formed inside the mold can be guided through the cavity to the outside of the mold.

[0057] It is understood that an extraction device may be provided through which the core gas is extracted from the casting mold.

[0058] In one embodiment of the invention, the mold comprises a further sand core, which is 3D-printed and has a space designed to accommodate a cooling element. By using a cooling element made of metal, a so-called cooling iron, the solidification of a light metal melt can be advantageously influenced in the area of ​​the cooling element; that is, a fine-grained cast structure is formed in the area around the cooling element, exhibiting particularly good mechanical properties. Furthermore, especially in aluminum-based melts, the formation of porosity in the area of ​​the cooling element, caused by hydrogen outgassing, is prevented in the casting. This so-called hydrogen porosity causes leakage, particularly in thin-walled channels, when a liquid medium, such as a coolant, passes through.

[0059] When using a casting mold according to the invention, cooling rates between 10 and 15 Kelvin per second are possible in an area located in the casting to be produced at a distance of between 3 and 5 mm from the cooling element, thereby achieving the aforementioned properties.

[0060] The inventors recognized that a cooling rate in the aforementioned range of 10 to 15 Kelvin per second and the aforementioned distance from the cooling element are sufficiently large to achieve the required casting properties. Furthermore, it was recognized that a higher cooling rate is not necessary, but rather detrimental, as this can lead to the formation of porosity.

[0061] In a further embodiment of the invention, the casting mold comprises an additional sand core and / or a permanent mold insert element, wherein the additional sand core is designed as an electric motor core and the permanent mold insert element is designed as an electric motor permanent mold insert element, and is provided to create a receiving space in the casting into which a stator and a rotor of an electric motor can be inserted.

[0062] A permanent mold insert is a reusable insert that, after the production of one casting, can be reused in a mold to produce another casting. Such a permanent mold insert can be used, for example, in die casting or other casting processes that utilize permanent molds.

[0063] The electric motor core or the electric motor permanent mold insert, which may be rotationally symmetrical, can, for example, be arranged horizontally in the mold so that, for example, in a gravity casting process, the molten metal does not rise longitudinally along it, but rather flows circumferentially around the electric motor core or the electric motor permanent mold insert. The inventors have determined that longitudinal rising of the molten metal along the electric motor core or the electric motor permanent mold insert is not necessary to obtain a pore-free wall in the casting that defines a receiving space with cooling channels incorporated therein.

[0064] The mold according to the invention is suitable for producing a housing for an electric drive for a motor vehicle, whose electric motor is designed either as an internal rotor or as an external rotor.

[0065] Advantageously, the electric motor core is designed in multiple parts, with each electric motor core part having a draft angle that extends circumferentially in a longitudinal direction of the electric motor core over a lateral surface of the electric motor core, and / or the electric motor permanent mold insert element has a draft angle that extends circumferentially in a longitudinal direction of the electric motor permanent mold insert element over a lateral surface.

[0066] A draft angle is required for a shot sand core to allow removal from a typically two-part core-shooting tool. Depending on the core complexity, the draft angle for a shot sand core is between 0.5 and 2 degrees.

[0067] Preferably, the electric motor core is two-part and rotationally symmetrical, for example frustoconical or cylindrical, wherein each electric motor core part is rotationally symmetrical.

[0068] If the electric motor core is made of two parts, the two core parts can be arranged one behind the other in the longitudinal direction of the core and abut each other in a contact plane, forming a flush transition to create the electric motor core. Each of the two core parts can be the same size in the longitudinal direction of the electric motor core. It is also conceivable that the two core parts are of different sizes, particularly in the longitudinal direction of the electric motor core.

[0069] Each of the draft angles of the electric motor core parts can either slope downwards or upwards from an outer end of the electric motor core part towards the contact plane.

[0070] An electric motor core is created that has two draft angles, each extending, for example, over half of the entire electric motor core. Advantageously, the draft angle in the casting produced with the mold according to the invention, which results in a deviation of the receiving space for the stator and rotor from a cylindrical shape, is only half as large as it would be in a one-piece core. This significantly reduces the effort required for machining to create a cylindrical receiving space for the stator and rotor. The same applies analogously to the electric motor permanent mold insert element, which, however, can be formed in one piece or, like the electric motor core, in multiple parts.

[0071] By using a casting mold according to the invention with such an electric motor core or an electric motor permanent mold insert element, near-net-shape manufacturing of a casting is made possible.

[0072] It goes without saying that a further reduction in machining effort is possible through a three-, four- or five-part electric motor core or such an electric motor permanent mold insert element.

[0073] It is conceivable that a section of the outer surface of the electric motor core or the electric motor permanent mold insert element is formed by at least one cooling element.

[0074] In one embodiment of the invention, the mold is designed such that a normal to a molten front of a light metal melt, with which the mold is filled against the direction of gravity, is arranged obliquely to a normal to a region of the mold where the light metal melt comes into contact with the mold. In gravity casting or low-pressure casting, when using a mold according to the invention, which can be designed as a permanent mold such as a die or as a sand casting mold, a molten front can rise in the mold against the direction of gravity; that is, the normal to the molten front is arranged parallel and against the direction of gravity.

[0075] When the mold is filled with molten metal, the molding air is displaced by the molten metal and a mold cavity representing the casting to be produced is filled with the molten metal.

[0076] By angling the normal to the melt front relative to a normal to an area of ​​the mold where the melt comes into contact with the mold, a slope is advantageously formed extending with a directional component opposite to the direction of gravity. This slope allows the molding air to be evacuated from the mold to be directed away. Defects in the casting due to molding air inclusions are thus advantageously prevented.

[0077] It is understood that the orientation of the two normals—one pointing to the melt front and the other to a region of the mold—can be changed by altering the orientation of the mold during filling in the Earth's gravitational field. This is not exclusively, but particularly, necessary for the design of a so-called Rotacast process.

[0078] Such a design of the mold is particularly relevant in those mold areas where reinforcing or cooling fins are provided in the casting to be produced, i.e. elongated and narrow recesses, or cylindrical projections intended for receiving screws to attach components to a part made from the casting.

[0079] In a further embodiment of the invention, the mold includes an insert element designed to influence the flow characteristics of a molten light metal flowing into the mold, wherein the insert element is preferably configured as a casting filter or a casting filter cascade. The casting filter can be sponge-like and made of a ceramic material. The casting filter can have a porosity between 10 and 60 ppi (pores per inch), preferably between 25 and 55 ppi, and particularly preferably between 40 ppi and 50 ppi.

[0080] By using a casting filter or a casting filter cascade, homogenization of a light metal melt flow can be achieved when filling the mold, i.e., turbulences that can lead to casting defects such as oxide inclusions are advantageously prevented.

[0081] In one embodiment of the invention, the mold includes an insert element designed to remain in a casting produced with the mold and preferably configured as a component of the electric drive for which the casting is usable. Such a component can, for example, be a heating coil cast into a wall of the casting and used for preheating when the casting is used in an electric vehicle. Such a component can also be a reinforcing element, for example for a sand core or a bearing seat, which enables high mechanical stability and / or significantly improved tribological performance.

[0082] It is conceivable that the insert elements are designed as sensors.

[0083] Advantageously, the mold includes an insert element made of a material other than molding sand, which is designed for removal from a casting produced with the mold. Such an insert element can, for example, be provided to create a channel with a particularly small cross-section of less than 6 mm, preferably between 1 and 4 mm.

[0084] To ensure that the insert element can be completely removed from the casting, it can be designed to be hollow.

[0085] In one embodiment of the invention, the mold has an area with several additional sand cores, wherein the additional sand cores are provided for forming a receiving housing for power electronic components and / or transmission components of the electric drive when the casting is used for an electric drive of a motor vehicle.

[0086] In an electric drive, power electronic components include, for example, current transformers or inverters. A mold is advantageously created, allowing, for instance, the production of a housing for an electric drive to which additional component mounting spaces are integrally molded. This eliminates the need for a separate assembly step in which such a component mounting space is attached to the housing.

[0087] The inventors overcame the technical prejudice that individual components of an electric drive must be flanged to a housing and determined that it is advantageous to integrate them into a component receiving space that is integrally molded onto the housing.

[0088] In a further embodiment of the invention, the mold has a section with several additional sand cores. When the casting is used in an electric motor of a motor vehicle, these additional sand cores are designed to form cooling channels through which a cooling fluid can flow in a controlled manner. Such a section can be integrated into the housing of an electric motor as part of the casting to form a thermal management system for controlling the cooling or heating balance. The system allows, for example, in conjunction with a heat pump, the waste heat generated by the electric motor and power electronics to be utilized where needed, for instance, to heat the vehicle or to preheat or warm up a traction battery.By incorporating cooling channels into a casting, through which a cooling fluid flows controlled by a regulation device, their routing during motor assembly is advantageously unnecessary. Potential defects are prevented, motor assembly effort is significantly reduced, and cable length and the associated weight are decreased.

[0089] In one embodiment of the invention, a cavity is provided in at least one side part of the mold, which forms an additional riser. This cavity is fluidically connected to a mold cavity representing the casting via through channels. Typically, in gravity casting, the riser is located above the casting for solidifying a molten light metal that has been filled with a mold. Its riser necks are only connected to the casting on one upper surface. While this allows feeding of the entire casting, large-volume areas of the casting, such as those with thin walls between 1 and 4 mm thick, which are fluidically connected to the riser through these walls, cannot be adequately fed. Therefore, these areas are particularly susceptible to the formation of shrinkage cavities.By connecting an additional feeder to one side of the casting, castings with large dimensions and, in some areas, thin walls can be produced without defects, particularly without cavities. It is understood that the additional feeder is fluidically connected to the feeder located above the casting, which acts as the main feeder; that is, a cavity in the mold representing the main feeder and a cavity representing the additional feeder are connected to each other by through channels.

[0090] Particularly in the area of ​​a receiving chamber for a stator and rotor of the electric drive, a casting section below a thin wall, which may contain integrated cooling channels, can be supplied with heat. No cavities leading to the rejection of the casting are formed.

[0091] Advantageously, the mold incorporates a venting element that defines a venting channel and forms an inner mold wall section. This inner mold wall section defines a cavity that, when the mold is filled with molten metal, forms a casting.

[0092] A venting device can be particularly advantageous in permanent molds. The venting device can include venting nozzles, which are arranged, in particular, at the end of a venting channel facing a mold cavity. The venting nozzles can, for example, have venting slots.

[0093] For example, particularly large venting channels can be created that allow sufficient mold venting even with rapid mold filling and do not require any deviation from the casting geometry to be represented, since the venting medium forms a mold wall section.

[0094] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying drawings relating to these embodiments. The drawings show: Fig. 1 A first embodiment of a mold according to the invention for manufacturing a housing for an electric drive for a motor vehicle, Fig. 2 a further embodiment of a mold according to the invention for manufacturing a housing for an electric drive for a motor vehicle, Fig. 3 a detail of an embodiment of a mold according to the invention for manufacturing a housing for an electric drive for a motor vehicle, Fig. 4 a further embodiment of a mold according to the invention for manufacturing a housing for an electric drive for a motor vehicle, Fig. 5 an embodiment of a mold according to the invention for manufacturing a housing for an electric drive for a motor vehicle, Fig. 6 a special embodiment of a mold according to the invention for manufacturing a housing for an electric drive for a motor vehicle.

[0095] One in Fig. 1a in a perspective top view and in Fig. 1b in cross-section along a section AA from Fig. 1a The partially shown sand mold 1 with a base sand core 2 comprises a curved sand core 3 with an oval cross-sectional area 4. In this embodiment, the sand core 3 is arranged in the sand mold 1 such that a channel-forming section 5, located between two connecting sections 6, 7, can be completely surrounded by a molten light metal with which the sand mold 1 can be filled to produce a casting (dashed helical arrow 8). Each of the connecting end sections 6, 7 is connected to the sand mold 1 by a plug connection, whereby, for example, a channel inlet opening can be formed in the casting at a transition 9 of the connecting end section 6 to the base sand core 2.

[0096] The base sand core 2 also has a filling channel 10 through which a light metal melt can flow into the sand casting mold 1. It is conceivable that a Fig. 1 The pouring filter, not shown, is located in the filling channel 10 or in the area of ​​the filling channel 10.

[0097] In this embodiment, the channel to be produced in a casting is formed by the curved sand core 3, wherein a cavity forming the channel walls is formed in particular by a Fig. 1b shown in partial cross-section, in Fig. 1a The electric motor core 11, omitted for clarity, is limited. The electric motor core 11 is essentially cylindrical, with outer surface sections 12 formed by cooling elements 13 made of cast iron. The electric motor core 11 creates a receiving space in the casting, in which, in particular, a stator and a rotor of an electric drive can be arranged.

[0098] A in Fig. 1c The sand core 3 shown in a perspective top view differs from the one in Fig. 1a and 1b shown by the fact that the sand core 3 has a single connecting section 7 and a Fig. 1c Free end not marked with a reference.

[0099] Through the in Fig. 1c The sand core 3 shown can be used to create a blind-hole-like channel in a casting produced with the mold 1.

[0100] It will now be on Fig. 2 Reference is made where identical or equivalent parts are used with the same reference number as in Fig. 1 are designated and the letter a is appended to the relevant reference number.

[0101] One in Fig. 2a in a perspective view, in Fig. 2b in a top view and in Fig. 2c in a cut side view along section AA from Fig. 2b The partially shown sand casting mold 1a differs from the one in Fig. 1 This is shown by the fact that a horseshoe-shaped sand core 3a, as seen in plan view, has an additional support element 14, which is arranged between two connecting sections 6a, 7a. The support element 14 is made of molding sand and is integrally molded onto the sand core 3a.

[0102] In this embodiment, the horseshoe-shaped sand core 3a, as seen from above, is 3D-printed and has a cavity 15 and vent channels 16 through which so-called core gas can be extracted from the sand core 3a when the sand mold 1a is filled with a light metal melt. This can be particularly advantageous for sand cores with a high binder content that, when a mold cavity is filled with a light metal melt, are partially or completely surrounded by the light metal melt.

[0103] It will now be on Fig. 3 Reference is made where identical or equivalent parts are used with the same reference number as in Fig. 1 and 2 are designated and the letter b is appended to the relevant reference number.

[0104] A section of a sand casting mold 1b, shown schematically in cross-section, includes a deep, narrow recess 17 in a side part of the sand casting mold 1b, which is designed to form a reinforcing rib of a casting that can be produced with the sand casting mold. A normal 18 on an upper sand casting mold wall section 19 in the area of ​​the recess 17 is arranged obliquely to a normal 20 on a melt front 21 of a light metal melt, which, in this embodiment, rises in the sand casting mold 1b against a direction of action 22 of gravity to fill the mold.

[0105] The sand casting mold wall section 19 forms an inclined plane along which the molding air 23 displaced by the melt front 21 as it rises in the sand casting mold 1b can slide along an arrow 24. Advantageously, no molding air is trapped in the recess, thus preventing a casting defect that would lead to the rejection of the casting.

[0106] It is conceivable that a venting channel is routed through the sand casting mold wall section in order to direct mold air directly out of sand casting mold 1b.

[0107] It will now be on Fig. 4 Reference is made where identical or equivalent parts are used with the same reference number as in Fig. 1 bis 3 are designated and the letter c is appended to the relevant reference number.

[0108] During a Fig. 4 In a perspective view of a section of the sand casting mold 1c, a side wall core 25 is 3D-printed and has a through-channel 26 into which a cooling element 27 made of cast iron is inserted. Because the side wall core 25 is 3D-printed, the through-channel can be designed such that the cooling element 27 can be inserted into the side wall core 25 from outside the sand casting mold 1c and held in place by a force-fit connection.

[0109] It will now be on Fig. 5 Reference is made where identical or equivalent parts are used with the same reference number as in Fig. 1 bis 4 are designated and the letter d is appended to the relevant reference number.

[0110] During a Fig. 5a In a perspective top view of a sand casting mold 1d, shown in part, a two-part electric motor core 11d is arranged lying down in the sand casting mold 1d, where lying down means that a light metal melt filling the sand casting mold 1d flows around the essentially cylindrical electric motor core 11d in the circumferential direction, for example against a direction of action 22d of gravity, and not in the longitudinal direction along a cylinder axis 28.

[0111] Two electric motor core parts 29, 30, which are connected to each other by a plug connection and are in contact plane 31, form the electric motor core 11d and comprise in a Fig. 5b The perspective detail view shown on the electric motor core 11d shows recesses 32, which are for receiving in Fig. 1b Cooling elements are provided with reference numeral 13.

[0112] Although it is conceivable that the electric motor core is 3D printed, in this embodiment it is designed as a shot sand core.

[0113] Each electric motor core part 29, 30 has a draft angle 33 which extends circumferentially 34 over a lateral surface 35 and slopes down in the direction of an arrow 36.

[0114] It will now be on Fig. 6 Reference is made where identical or equivalent parts are used with the same reference number as in Fig. 1 bis 5 are designated and the letter e is appended to the relevant reference number.

[0115] One in Fig. 6a in a perspective view, in Fig. 6b in a top view and in Fig. 6c in a cut side view in section AA from Fig. 6b The sand casting mold 1e shown comprises a cavity 37, which represents a main feeder for a casting that can be produced with the sand casting mold 1e, and which is arranged above the casting when the casting solidifies. Through passage channels 38, there is a fluidic connection between the cavity 37 and a [missing information - likely a specific component or element] in Fig. 6 The mold cavity depicting the casting, which is not shown.

[0116] A cavity 40 is incorporated into a multi-part side wall core 39 of the sand casting mold 1e, which represents an additional feeder attached laterally to the produced casting and which is fluidically connected to the cavity 37 representing the main feeder by several through channels 41.

[0117] A fluidic connection between the cavity 40 representing the additional feeder and the mold cavity representing the casting is ensured by through channels 42. For the sake of clarity, not all through channels 42 are labeled with a reference numeral.

[0118] It is conceivable that a mold (1-1e) is provided for the production of a housing for an electric drive and has an area with several additional sand cores which is set up to form a receiving housing for power electronic components and / or gear components of an electric drive.

[0119] Furthermore, a casting mold (1-1e) can have several additional sand cores which, when the casting is used in an electric motor of a motor vehicle, are provided to form cooling channels through which a cooling fluid flows in a controlled manner.

[0120] Furthermore, it is conceivable that a mold (1-1e) may have an insert element designed to remain in a casting produced with the mold. This could, for example, be a component of an electric drive, for the manufacture of which the casting is used.

[0121] It goes without saying that all possible combinations of features of the in Fig. 1 bis 6 The features shown are conceivable. For example, a Fig. 6 The sand casting mold shown has a recess 17 according to Fig. 3 exhibit.

[0122] It is also understood that a casting mold according to the invention can be designed as a permanent casting mold. A permanent casting mold can, for example, be a die-casting mold or a pressure-casting mold into which sand cores are inserted.

Claims

1. Casting mold (1-1e) for producing a housing for an electric drive for a motor vehicle formed from a light metal alloy, wherein 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) in such a way that the at least one sand core (3; 3a; 3c) can be completely surrounded in a circumferential direction by a light metal melt with which the casting mold is filled to form the casting, wherein the at least one sand core (3; 3a; 3c) is designed as a cooling channel core, wherein the at least one sand core (3; 3a; 3c) is bent at least in some regions, characterized in that a ratio of a length of the sand core (3; 3a; 3c) to a sand core cross-sectional size is between 7.5 and 38, the sand core cross-section size is the distance between two points of the sand core cross-section that are furthest apart, that the smallest sand core cross-sectional size in a sand core with regions with different sand core cross-sectional sizes is used to form the ratio, and the sand core cross-sectional size is at least 1.6 mm.

2. Casting mold according to claim 1, characterized in that the at least one sand core (3; 3a; 3c) is elongated and preferably has supporting elements (14) by means of which the sand core (3; 3a; 3c) is connected to the casting mold (1-1e) or to another sand core, wherein supporting elements (14) adjacent in a longitudinal direction of the sand core are spaced apart from one another by between 60 mm and 200 mm, preferably between 90 mm and 150 mm, particularly preferably between 99 mm and 121 mm.

3. Casting mold according to claim 1 or 2, characterized in that the at least one sand core (3; 3a; 3c) has at least one connecting section (6, 7; 6a, 7a) which is designed to form a form-fitting, force-fitting and / or material-locking connection with the casting mold ( 1-1e) or another sand core, wherein preferably alignment bevels and / or venting channels (16) are provided in the region of a transition (9; 9c) from the at least one connecting section to the casting mold (1-1e) or the other sand core.

4. Casting mold according to any one of claims 1 to 3, characterized in that the at least one sand core (3; 3a; 3c) is 3D-printed and preferably has at least one cavity (15) or comprises regions into which no binder is introduced.

5. Casting mold according to any one of claims 1 to 4, characterized that the casting mold comprises a further sand core (25) which is 3D-printed and has a space (26) which is designed to receive a cooling element (27).

6. Casting mold according to any one of claims 1 to 5, characterized in that the casting mold (1-1e) comprises an additional sand core (11; 11d) and / or a permanent mold insert element, wherein the additional sand core (11; 11d) is designed as an electric motor core and the permanent mold insert element is designed as an electric motor permanent mold insert element, and is provided to map a receiving space in the casting into which a stator and a rotor of an electric motor can be introduced.

7. Casting mold according to claim 6, characterized in that the electric motor core (11; 11a) is of a multi-part design, wherein each electric motor core part (29, 30) has a demoulding bevel (33) which extends in a longitudinal direction of the electric motor core over a circumferential surface (35), and / or the electric motor permanent mold insert element has a demoulding bevel which extends in a longitudinal direction of the electric motor permanent mold insert element over a circumferential surface.

8. Casting mold according to any one of claims 1 to 7, characterized in that the casting mold (1-1e) has an insert element which is configured to influence the flow properties of a light-metal melt flowing into the casting mold, the insert element being designed in particular as a casting filter or as a casting filter cascade.

9. Casting mold according to any one of claims 1 to 8, characterized in that the casting mold (1-1e) has an insert element which is intended to remain in a casting produced by means of the casting mold and is preferably designed as a component of the electric drive for which the casting can be used.

10. Casting mold according to any one of claims 1 to 9, characterized in that the casting mold (1-1e) has an insert element formed from a material other than foundry sand, which is provided for removal from a casting produced with the casting mold.

11. Casting mold according to any one of claims 1 to 10, characterized in that the casting mold (1-1e) has an area with a plurality of further sand cores, the further sand cores being provided for mapping a housing for power electronics components and / or transmission components of the electric drive when the casting is used for an electric drive of a motor vehicle.

12. Casting mold according to any one of claims 1 to 11, characterized in that the casting mold (1-1e) has an area with a plurality of additional sand cores, the plurality of additional sand cores being provided for mapping cooling channels through which a cooling fluid can flow in a controlled manner when the casting is used in an electric motor of a motor vehicle.

13. Casting mold according to any one of claims 1 to 12, characterized in that a cavity (40) is formed in at least one side part (39) of the casting mold (1-1e), which forms an additional feeder, wherein the cavity (40) is fluidically connected by through-channels (42) to a mold cavity forming the casting.

14. Method for producing a housing for an electric drive for a motor vehicle with a casting mold according to one of claims 1 to 13, characterized in that at least one sand core (3; 3a; 3c) arranged in a casting mold is completely surrounded, at least in sections, in a circumferential direction, by a light-metal melt, with which the casting mold is filled to form the casting.

15. Method according to claim 14, characterized in that a channel bent in sections is formed in the casting through the sand core (3; 3a; 3c) surrounded in sections in a circumferential direction by the light-metal melt.

16. Method according to claim 14 or 15, 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) at 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.

17. Method according to any one of claims 14 to 16, characterized in that a movement speed of a permanent mold that is moved during mold filling is adjustable.