Device for press casting

Abstract

Device (1) for pressure casting, in particular for producing a rotor of an electric motor, comprising a casting mold (2) with a casting cavity (20), an ejector plate (3) with ejector punches (4), a pressing device (5) which is designed to move the ejector plate (3) in a pressing process in the direction of the casting cavity (20), an ejector device (6) which is designed to move the ejector plate (3) in an ejection process in the direction of the casting cavity (20), and at least one telescopic column (7) which mechanically connects the ejector device (6) and the ejector plate (3) to one another, wherein the telescopic column (7) is designed to be extendable in the axial direction.

Description

[0001] The present invention relates to a device for pressure casting and a method for pressure casting.

[0002] Pressure casting devices are known, which can be used to produce rotors for electric motors, for example. Pressure casting can also be referred to as "squeeze casting." Typically, this process involves die casting, with additional pressing tools, so-called "squeezers," being used to prevent porosity caused by volume contraction during solidification by squeezing the component and / or by additionally pressing in material. However, due to the component geometry and the often limited space available, integrating squeezers into the die casting tool is often difficult or impossible.

[0003] It is therefore an object of the present invention to provide a compression molding device with which components with optimal material properties can be produced efficiently and cost-effectively using a compression molding device. Furthermore, it is an object of the invention to provide a compression molding method with which components with optimal material properties can be produced simply, cost-effectively, and time-efficiently.

[0004] The object is achieved by a device according to claim 1 and by a method according to claim 11.

[0005] The device for compression molding according to the invention is preferably configured for producing a rotor of an electric motor, preferably an asynchronous motor, and comprises a mold with a molding cavity, an ejector plate with ejector punches, a pressing device, an ejector device, and at least one telescopic column. The pressing device is configured to move the ejector plate toward the molding cavity during a pressing process. Furthermore, the ejector device is configured to move the ejector plate toward the molding cavity during an ejection process. The telescopic column mechanically connects the ejector device and the ejector plate to one another. The telescopic column is designed to be extendable in the axial direction.

[0006] In other words, a device for compression molding is provided which allows both squeezing of the casting material, preferably during solidification, and ejection of the solidified component, particularly with the mold open. Squeezing and ejection are each performed by means of the ejector plate with the ejector punches, in which the ejector punches are pushed from the ejector plate at least partially into the casting cavity in order to press on the casting material located therein. This means that the ejector punches are configured both for squeezing the casting material and for ejecting the solidified component. The ejector plate can form a fastening and actuation mechanism for the ejector punches.

[0007] The pressing device is optimized, for example, for squeezing the casting material during the pressing process. Preferably, the pressing device can exert high forces on the ejector plate during the pressing process in order to achieve effective compaction of the casting material. Preferably, the pressing device can be configured to move the ejector plate only a small maximum pressing travel. The pressing travel can preferably be in the range of a few millimeters, preferably a maximum of 100 mm, preferably a maximum of 50 mm, in particular a maximum of 25 mm.

[0008] The ejector device can, for example, be optimized for ejecting the finished component during the ejection process. The ejector device can preferably move the ejector plate over a large ejection distance to ensure reliable ejection of the component. The ejection distance can preferably be a multiple of the pressing distance, preferably at least 5 mm, preferably at least 25 mm, particularly preferably at least 50 mm, and in particular at least 100 mm.

[0009] The device according to the invention offers the advantage that both squeezing and ejection can be performed easily and reliably using a particularly simple and cost-effective design. By using the ejector plate together with the ejector punches for squeezing and ejection, separate design of corresponding elements can be avoided. This allows for space savings, especially in the area of the mold, and allows for particularly efficient use of the available space.

[0010] The at least one telescopic column enables reliable squeezing and ejection. In particular, the telescopic column allows the pressing device to be decoupled from the ejector plate with the ejector punches, while the telescopic column enables simple and robust connection and mounting of the ejector device and the ejector plate. In detail, the telescopic column allows the ejector plate to be easily moved independently of the ejector device during the pressing process, in which the ejector plate is advanced by the pressing device, despite its connection to the ejector device. For example, this allows an ejector system to be combined with a pressing system in a simple and efficient manner.Because the pressing device is provided separately and can move the ejector plate independently, necessary safety requirements, such as locking the ejector device, can be implemented without restricting squeezing.

[0011] Preferably, the telescopic column is designed to be extendable by a predetermined pressing length. In particular, the pressing length is at least 10 mm, preferably at least 20 mm, and particularly preferably a maximum of 50 mm. This allows, on the one hand, a sufficiently long pressing path to enable reliable squeezing of the casting material. For example, an excessively long pressing path and thus excessive movement of the ejector plate by the pressing device can be avoided to prevent damage to the component to be cast or the device.

[0012] Preferably, the ejector plate and the ejector punch are firmly connected to each other. This means that the ejector punches are mechanically fixed to the ejector plate. For example, the ejector punch and ejector plate can also be formed together as a single, integral component. This allows for a simple, cost-effective, and particularly robust design.

[0013] Particularly preferably, the ejector plate and the pressing device are mechanically unconnected. This means that the ejector device and the ejector plate are not mechanically fixed to one another. In particular, the pressing device can press exclusively against the ejector plate in such a way as to move it toward the casting cavity. This allows the ejector plate to be moved independently of the pressing device, which in particular enables simple and flexible ejection by means of the movement of the ejector plate by the ejector device during the ejection process.

[0014] Further preferably, the telescopic column is constructed in two parts and has a first telescopic element and a second telescopic element. The first telescopic element and the ejector plate are firmly connected to one another, i.e., in particular, mechanically fixed to one another, or alternatively, preferably formed together as a one-piece component. In addition, the second telescopic element and the ejector device are firmly connected to one another, i.e., in particular, mechanically fixed to one another, or alternatively, preferably formed together as a one-piece component. Preferably, the first telescopic element and the second telescopic element are constructed and arranged to be movable relative to one another in the axial direction. This makes it possible to provide a simple and robust construction of the device with few components.

[0015] Preferably, the two telescopic elements of the telescopic column are designed and arranged to be at least partially telescopic. Preferably, the first telescopic element is at least partially retractable into the second telescopic element. This allows for the possibility of extending the telescopic columns in the axial direction in a simple and robust manner.

[0016] Preferably, the at least one telescopic column has a return element which is designed to return the axial extension of the telescopic column by means of a return force. Preferably, the return element is a spring which is preferably arranged between the two telescopic elements. In particular, the return element is designed such that the return force causes the two telescopic elements to be pushed into one another. This makes it possible in a particularly simple and cost-effective manner for the ejector plate and the ejector punch to be automatically returned after the pressing process. This means, for example, that no separate actuation for returning after the pressing process is necessary, for example by actuation via the pressing device.

[0017] Preferably, the pressing device and / or the ejector device comprises at least one hydraulic unit. In particular, the hydraulic unit can comprise a hydraulic cylinder. This means that the ejector plate is moved by means of the pressing device and / or the ejector device using hydraulic force. This enables high forces to move the ejector plate and precise movement of the ejector plate.

[0018] More preferably, the device further comprises a locking device configured to lock the movement of the ejector device. In particular, the locking device is configured to lock the movement of the ejector device during a casting process and / or during the pressing process. This means that a movement of the ejector plate initiated by the ejector device can be blocked by the locking device. This allows for particularly simple and reliable control of the components without undesired movements that could, for example, cause damage to the components and / or the device, while maintaining a simple system design.

[0019] Preferably, the ejector plate with the ejector punches is configured to provide a material reservoir in the casting cavity. In particular, the material reservoir is designed to hold casting material to be pressed during the pressing process. This means that the ejector punches are configured to provide, in addition to the actual component cavity, a certain amount of space into which casting material can flow, which can be pressed during the pressing process. This allows components with the desired geometries and particularly good material properties to be provided by the device.

[0020] Furthermore, the invention leads to a method for pressure casting, in particular for producing a rotor of an electric motor. The method is preferably carried out using the described pressure casting device. The method comprises the following steps, which are carried out successively, in particular in the described order: - Filling casting material into the casting cavity of the casting mold, - Moving the ejector plate towards the casting cavity to squeeze casting material during the pressing process by means of the pressing device, - Reset the pressing device, and - Moving the ejector plate toward the casting cavity to eject the cast component during the ejection process using the ejector device. In particular, the ejector plate is moved for ejection after the casting material has solidified.

[0021] Preferably, the method also allows the pressing device to be left in the forward end position after squeezing. In this case, the pressing device can be reset at a later time.

[0022] The invention is explained in more detail below using an exemplary embodiment. In the drawings: Fig. 1 is a highly simplified schematic view of a device for pressure casting according to a preferred embodiment of the invention, and Fig. 2 a detailed view of the device of the Fig. 1.

[0023] In the following, a preferred embodiment of a device 1 for pressure casting is explained. Fig. 1 and Fig. 2. Identical or functionally identical components are always provided with the same reference symbols.

[0024] Rotors for electric motors, in particular for asynchronous motors, can be manufactured by means of the device 1 according to the invention. Such rotors comprise a laminated core having a plurality of laminations stacked along a laminated core axis. This laminated core has a plurality of axial grooves and / or through-holes into which a highly electrically conductive metal is to be introduced in order to form axial bars through the laminated core. In addition, a short-circuit ring is provided on each of the two axial end faces of the laminated core, which extends in the circumferential direction and connects all of the bars to one another. By means of the device 1, the bars and short-circuit rings can be cast directly into or onto the laminated core as a single, one-piece component and in a single step. This component is referred to below as the component to be cast.

[0025] The component to be cast is preferably cast from aluminum or an aluminum alloy.

[0026] The device 1 is designed to produce the component by means of compression molding, which comprises die casting with additional squeezing.

[0027] The device 1 comprises a casting mold 2 with a casting cavity 20 into which the casting material is poured in order to produce the component to be cast.

[0028] In addition, the device 1 comprises an ejector plate 3 with several ejector punches 4. The ejector plate 3 and the ejector punches 4 are fixedly, i.e. immovably, connected to one another.

[0029] Preferably, the ejector punches 4 are designed as rods, in particular cylindrical.

[0030] All ejector punches 4 extend parallel to an axis 45 and can be introduced into the casting cavity 20 by moving the ejector plate 3 along the axis 45. As a result, the ejector punches 4 can be used, on the one hand, to squeeze the casting material within the casting cavity 20 in a pressing process, and, on the other hand, to eject the manufactured component after casting, and in particular after solidification, in an ejection process, i.e., to press it out of the opened casting mold 2.

[0031] Preferably, the ejector punches 4 are designed in such a way and in a normal position (which is Fig. 1 is shown by way of example) such that a material reservoir 9 for casting material to be pressed during the pressing process is formed in the casting cavity 20.

[0032] For squeezing and ejection, the device 1 has separate devices that can be operated independently of one another. In detail, the device 1 has a pressing device 5 configured to move the ejector plate 3 toward the casting cavity 20 during the pressing process, for squeezing the material. Furthermore, the device 1 has an ejector device 6 configured to move the ejector plate 3 toward the casting cavity 20 during the ejection process, for ejecting the manufactured component.

[0033] The pressing device 5 and the ejector device 6 can each have a hydraulic unit in order to be able to implement the movement of the ejector plate 3 by means of a hydraulic force.

[0034] Pressing device 5 and ejector device 6 can preferably be controlled by means of a control unit 50, preferably independently of each other.

[0035] The pressing device 5 is designed and arranged mechanically unconnected to the ejector plate 3. For example, the pressing device 5 can be mounted on a stationary holder 29 (see Fig. 2), wherein the pressing device 5 can have an ejector punch 51 which can press against the ejector plate 3 by means of the hydraulic unit in order to move it in the direction of the casting cavity 20.

[0036] The ejector device 6, on the other hand, is directly connected to the ejector plate 3 by means of several telescopic columns 7. The telescopic columns 7 are essentially cylindrical and also extend parallel to the axis 45.

[0037] Each telescopic column 7 is designed to be extendable in the axial direction. For this purpose, each telescopic column 7 is constructed in two parts and has a first telescopic element 71 and a second telescopic element 72.

[0038] The first telescopic element 71 is firmly connected to the ejector plate 3, for example by means of a screw 37. The second telescopic element 72 is firmly connected to the ejector device 6, for example by means of a screw 67.

[0039] The two telescopic elements 71, 72 are designed and arranged to be slidable into one another. In detail, the second telescopic element 72 is at least partially hollow-cylindrical, with the first telescopic element 71 being partially arranged inside this hollow-cylindrical region.

[0040] Preferably, the first telescopic element 71 has a head region 71b, which is arranged outside the second telescopic element 72 and has a larger outer dimension in the radial direction than the second telescopic element 72. Preferably, the head region 71b is connected to the ejector plate 3. As a result, in the axially unextended state of the telescopic column 7, the second telescopic element 72 can bear directly against the head region 71b, thereby providing a direct and robust force transmission path from the ejector device 6 to the ejector plate 3.

[0041] The axial extensibility of the telescopic column 7 is limited to a predetermined pressing length 70. This is achieved by forming a recess 72a within the hollow cylindrical region of the second telescopic element 72, which recess has a larger diameter than the rest of the hollow cylindrical region. Arranged within this recess 72a is a mushroom-shaped region 71a of the first telescopic element 71, which has an inner diameter substantially corresponding to the recess 72a. The mushroom-shaped region 71a thus positively prevents the first telescopic element 71 from being pulled out of the second telescopic element 72 by more than the pressing length 70.

[0042] The telescopic column 7 further comprises a return element 75, which is designed as a compression spring and is configured to return the axial extension of the telescopic column 7 by means of a return force 76. The return element 76 is arranged between the mushroom region 71a and the narrower part of the hollow cylindrical region of the second telescopic element 72.

[0043] The device 1 offers the advantage that high-quality components can be cast with a particularly simple and cost-effective design. The use of the ejector plate 3 with the ejector punch 4 for both squeezing and ejection allows for a particularly space-saving design, particularly in the area of the casting mold 2.

[0044] Since the pressing device 5 and the ejector device 6 are provided separately for squeezing and ejecting, respectively, a flexible and optimally adapted operation can be provided in the pressing process and the ejecting process.

[0045] During component production, the casting material is first filled into the casting cavity 20 and then pressed over the ejector punches 4 by means of the pressing device 5. The axial extendability of the telescopic columns 7 allows free movement independent of the ejector device 6.

[0046] In this case, it is also possible for the ejector device 6 to be specifically locked by a locking device 8, at least during the pressing process, preferably during the entire casting process. This means that the locking device 8 prevents any movement of the hydraulic ejector cylinder of the ejector device 6.

[0047] This can prevent, for example, an unintentional movement of the ejector device 6 during the casting process, which can lead, for example, to damage to parts of the device 1 and / or the component to be produced.

[0048] After completion of the pressing process, the return element 75 of the telescopic column 7 can automatically enable the ejector plate 3 with the ejector punches 4 to move back in the axial direction. This eliminates the need for an additional active return of the ejector plate 3, for example, by a hydraulic unit.

[0049] After completion of the casting process, in particular after the casting material has solidified, the casting mold 2 can be opened and the telescopic columns 7, and thus also the ejector plate 3 and the ejector punches 4, can be advanced by means of the ejector device 6 in order to eject the component from the casting mold 2. The ejector device 6 can advance the ejector plate 3 by a significantly greater ejection distance compared to the pressing length 70. List of reference symbols 1 device 2 casting mold 3 Ejector plate 4 ejector punches 5 Pressing device 6 Ejector device 7 Telescopic column 8 Locking device 9 Material reservoir 20 casting cavities 29 Bracket 37 screw 45 axis 50 control unit 51 ejector punches 67 screw 70 pressing length 71 first telescopic element 71a Mushroom area 71b Head area 72 second telescopic element 72a recess 75 Reset element 76 Restoring force

Claims

[1] Device (1) for pressure casting, in particular for producing a rotor of an electric motor, comprising: - a casting mould (2) with a casting cavity (20), - an ejector plate (3) with ejector punches (4), - a pressing device (5) which is arranged to move the ejector plate (3) in a pressing process in the direction of the casting cavity (20), - an ejector device (6) which is arranged to move the ejector plate (3) in an ejection process in the direction of the casting cavity (20), and - at least one telescopic column (7) which mechanically connects the ejector device (6) and the ejector plate (3), - wherein the telescopic column (7) is designed to be extendable in the axial direction. [2] Device according to claim 1, wherein the telescopic column (7) is designed to be extendable by a predetermined pressing length (70), in particular wherein the pressing length (70) is at least 10 mm, preferably at least 20 mm, in particular a maximum of 50 mm. [3] Device according to one of the preceding claims, wherein the ejector plate (3) and the ejector punches (4) are firmly connected to one another. [4] Device according to one of the preceding claims, wherein the ejector plate (3) and the pressing device (5) are mechanically unconnected. [5] Device according to one of the preceding claims, - wherein the telescopic column (7) is formed in two parts and has a first telescopic element (71) and a second telescopic element (72), - wherein the ejector plate (3) and the first telescopic element (71) are firmly connected to one another, and - wherein the ejector device (6) and the second telescopic element (72) are firmly connected to one another. [6] Device according to claim 5, wherein the two telescopic elements (71, 72) are designed and arranged to be at least partially slidable into one another. [7] Device according to one of the preceding claims, wherein the telescopic column (7) has a restoring element (75) which is arranged to restore the axial extension of the telescopic column (7) by means of a restoring force (76). [8] Device according to one of the preceding claims, wherein the pressing device (5) and / or the ejector device (6) comprises at least one hydraulic unit. [9] Device according to one of the preceding claims, further comprising a locking device (8) which is designed to lock the movement of the ejector device (6), in particular in a casting process and / or during the pressing process. [10] Device according to one of the preceding claims, wherein the ejector plate (3) with the ejector punches (4) is designed to provide a material reservoir (9) for casting material to be pressed during the pressing process in the casting cavity (20). [11] Method for pressure casting, in particular for producing a rotor of an electric motor, preferably by means of a device (1) according to one of the preceding claims, comprising the steps: - Filling casting material into the casting cavity (20), - moving the ejector plate (3) towards the casting cavity (20) for squeezing casting material during the pressing process by means of the pressing device (5), - Reset the pressing device (5), - Moving the ejector plate (3) in the direction of the casting cavity (20), in particular after the casting material has solidified, to eject the cast component during the ejection process by means of the ejector device (6).

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