EP3678803B1 - Method for producing a cast workpiece - Google Patents

Description

The invention relates to a method for producing a cast workpiece.

In the production of workpieces by casting processes, a molten metal, for example a molten aluminum, is usually introduced into molds. In this document, the term metal melt is understood to mean not only liquid but also thixotropic metal melts. After the molten metal has solidified and cooled, the workpiece is removed from the mold and a mold core located in the workpiece is smashed. With conventional methods, it is usual to cool the workpieces to a temperature of approx. 80 ° C before they are cored. The core is removed at a relatively low temperature, since at this point in time the structure of the workpiece is essentially no longer subject to any changes.

From the WO 2016/201474 A1 , as well as from the EP 1 721 689 A1 methods are known in which the coring process is carried out at an elevated temperature. In this case, however, the workpiece can be damaged because the heated material structure of the workpiece is still weak.

From the FR 2 954 195 A1 , the GB 2 348 839 A and the DE 36 37 367 A1 other coring machines are known.

The present invention is based on the object of creating a method in which the economy in the production of cast workpieces is increased and the workpiece is not damaged.

This object is achieved by a method according to the claims.

• Bereitstellen einer Gussform mit zumindest einem in der Gussform angeordneten Formkern;
• Einbringen einer Metallschmelze in die Gussform;
• Warten einer Zeitdauer, bis zumindest die Außenkontur der Metallschmelze erstarrt ist und aus der Metallschmelze das Werkstück geformt ist;
• Entfernen des Werkstücks aus der Gussform;
• Zertrümmern des Formkernes, wobei dieser Verfahrensschritt durchgeführt wird, noch bevor das Werkstück vom Gussvorgang vollständig abgekühlt ist.

According to the invention, a method for producing a cast workpiece is provided, the method comprising the following method steps:

• Providing a casting mold with at least one mold core arranged in the casting mold;
• Introducing a molten metal into the casting mold;
• Waiting for a period of time until at least the outer contour of the molten metal has solidified and the workpiece has been formed from the molten metal;
• Removing the workpiece from the mold;
• Smashing the mold core, this process step being carried out before the workpiece has completely cooled down from the casting process.

To smash the mold core, a hammer head is placed on a defined energy transfer surface of the workpiece and the hammer head acts on the energy transfer surface, in particular hammered in.

The method according to the invention has the surprising advantage that the shattering of the mold core can take place at an increased process temperature and thus the process can be further optimized. In contrast to the prior art, an energy transfer surface of the workpiece, on which a hammer head is applied to smash the mold core, is defined in advance. The energy transfer surface can thus be designed in such a way that it has a higher strength than the other surfaces or that any deformations on the energy transfer surface can be removed again in subsequent processing steps. This makes it possible to shatter the mold core at a higher core temperature than is possible with methods known from the prior art. Which surface of the workpiece serves as the energy transfer surface can already be determined during the construction of the workpiece or during the simulation of the casting process. Furthermore, it is also conceivable that tests are carried out to determine which area is best suited as an energy transfer area. It is advantageous if it is specified in a work instruction which surface of the workpiece can or may serve as an energy transfer surface.

Furthermore, it can be expedient if a surface of the workpiece serves as the energy transfer surface, which surface is processed mechanically, in particular by cutting, in subsequent production steps. The advantage here is that any damage or plastic deformations of the energy transfer surface which are introduced into it during the process of shattering can be removed again in subsequent process steps.

Furthermore, it can be provided that a surface of the workpiece which has the greatest surface strength at the time of the shattering of the mold core serves as the energy transfer surface. The advantage here is that this measure reduces the deformation of the Workpiece can be kept as low as possible during the process of shattering the mold core.

In addition, it can be provided that a surface of the workpiece serves as the energy transfer surface which was arranged during the casting process, in particular during the gravity casting process, in the area of a lower part of the casting mold, in particular in relation to the casting layer on an underside of the workpiece. The advantage here is that, in relation to the cast layer, the lower area of the workpiece solidifies first and thus has the greatest surface strength. This results from the fact that the melt introduced into the casting mold is first calmed in this area and first comes into contact with the cooling casting mold.

In particular, it is useful that the energy transfer surface is where the melt is first calmed down.

An embodiment is also advantageous, according to which it can be provided that the workpiece is turned through 180 ° after it has been removed from the mold, so that the energy transfer surface lies on the upper side of the workpiece and the workpiece rests on a support table on a support side opposite to the energy transfer surface. As a result of this measure, the hammer head of the coring hammer can act on the workpiece in the vertical direction from above. The workpiece can be placed on the support table.

According to a further development, it is possible that the workpiece is designed as a cylinder head blank for further processing into a cylinder head for an internal combustion engine, an engine block connection surface of the cylinder head blank serving as the energy transfer surface. In the case of cylinder heads in particular, coring at high temperatures is associated with great economic advantages. Defining the engine block connection surface as an energy transfer surface has the advantage that, on the one hand, the engine block connection surface can be at the bottom during the casting process and, on the other hand, is still milled off in subsequent processing steps. Thus, on the one hand, the deformations on the engine block connection surface during the shattering of the core can be kept as low as possible. On the other hand, the introduced deformations can be removed again in subsequent processing steps, so that there are no longer any traces of action on the finished cylinder head. It is particularly advantageous here that the engine block connection surface of the cylinder head has to be machined anyway in order to obtain a flat surface. Another advantage of using the engine block connection surface as an energy transfer surface is that it is a surface that is flat and has a large surface area. In this way, the force applied can be distributed over a large area, which means that the surface pressure can be kept as low as possible.

Furthermore, it can be expedient if the energy transfer surface is designed as a flat surface. The advantage here is that the hammer head can also have a flat surface and can therefore rest over the entire surface of the energy transfer surface of the workpiece.

In addition, it can be provided that an area of an effective area of the hammer head or the load sharing plate, which rests on the energy transfer surface when the mold core is smashed, is between 150% and 10%, in particular between 110% and 50%, preferably between 100% and 80% Area of the energy transfer surface is. The advantage here is that the lowest possible surface pressure can be achieved through this surface dimensioning.

Furthermore, it can be provided that the workpiece is removed from the mold when the surface temperature of the energy transfer surface is between 440 ° Celsius and 360 ° Celsius. The advantage here is that the workpiece already has sufficient strength at this temperature to be manipulated.

In addition, it can be provided that the workpiece cools down further during the feeding of the workpiece to a hammer head for smashing the mold core until the energy transfer surface has a surface temperature between 300 ° Celsius and 400 ° Celsius. A workpiece that has a temperature in the specified range on the energy transfer surface already has sufficient strength to be able to act on the energy transfer surface by means of the hammer head.

Furthermore, it can be provided that the shattering of the mold core by means of the hammer head takes place at a surface temperature of the energy transfer surface between 300 ° Celsius and 400 ° Celsius, with at least external parts of the mold core being shattered. In particular, it can be provided that in this processing step only external parts or parts of the mold core close to the edge are shattered, in particular cracked through, and thus fall off the workpiece. As a result, the outer surface of the workpiece can be freed from the mold cores, so that the workpiece can cool down more quickly. Even if the external mold cores are not completely removed or knocked off from the workpiece, but only detach themselves from the workpiece surface, the cooling effect can be improved.

In addition, it can be provided that in the method step described above, the hammer head impacts the workpiece for between 1 seconds and 20 seconds.

Furthermore, it can be provided that after at least parts of the mold core have been smashed, the workpiece is further cooled until the energy transfer surface has a surface temperature between 100 ° Celsius and 200 ° Celsius, in particular between 150 ° Celsius and 200 ° Celsius, and that the workpiece is then again a Hammer head is supplied for smashing the mold core, with the remaining parts of the mold core also being smashed, in particular parts inside the workpiece. The advantage here is that in this process step, those parts of the mold core can also be smashed which are arranged within the workpiece.

According to a particular embodiment, it is possible that after the shattering of the mold core, the workpiece is clamped in a vibrating device and the workpiece is rotated about at least one horizontal axis of rotation while vibrating at the same time. The advantage here is that the mold core can be smashed further by this measure or that the shattered mold core parts can be removed from the workpiece in this process step.

According to an advantageous further development, it can be provided that when the mold core is smashed, several hammer heads are simultaneously applied to the energy transfer surface act. The advantage here is that the necessary energy can be introduced into the workpiece by several hammer heads at the same time.

In particular, it can be advantageous if a load sharing plate is inserted between the hammer head and the energy transfer surface. The advantage here is that the surface pressure on the energy transfer surface can be kept as low as possible by means of the load sharing plate.

Furthermore, it can be provided that a cooling channel is formed in the casting mold, at least in that area in which the energy transfer surface of the workpiece is formed, the workpiece being cooled by means of the cooling channel in the area of the energy transfer surface. The advantage here is that the energy transfer surface can be cooled by means of the cooling channel and that it can therefore have a high surface strength compared to the rest of the workpiece.

In addition, provision can be made for the energy transfer surface to be locally cooled after the workpiece has been removed from the casting mold, for example by dipping the energy transfer surface of the workpiece in a cooling liquid. As a result, the energy transfer surface can have a high level of strength, and the rest of the workpiece can be kept at a high temperature level.

According to the invention, a coring hammer carrier is provided for shattering the mold core of a cast workpiece, the coring hammer carrier having at least one coring hammer with a hammer head. Furthermore, a load sharing plate is provided which can be brought between the hammer head and the workpiece. The advantage here is that the load sharing plate can be used to avoid introducing a high surface pressure on the workpiece.

In addition, it can be provided that the load sharing plate is coupled to at least two hammer heads of two de-core hammers. The advantage here is that the hammer heads of the two core hammers are coupled to one another by this measure.

Furthermore, it can be provided that the load sharing plate is coupled to the hammer heads of the coring hammers in a separable manner. As a result, different load sharing plates can be provided for different workpieces, it being possible for the load sharing plates to be selectively exchanged.

In particular, it can be provided that the contour of the load sharing plate is adapted to the surface contour of the energy transfer surface of the workpiece.

In addition, it can be provided that the load sharing plate has a flexible surface quality in the area in which it rests on the energy transfer surface of the workpiece. As a result, the load sharing plate can be flexibly adapted to the energy transfer surface of the workpiece.

Furthermore, it can be provided that the feeder of the workpiece has the energy transfer surface. In particular, this measure can be useful if a sand mold is used as the casting mold. The mold has an insulating effect, so that the workpiece cannot cool down. If the energy transfer surface is selected on the feeder, the sand casting mold can be knocked off the workpiece in order to facilitate the cooling of the workpiece.

Furthermore, it is also conceivable that when the mold core is smashed, not only the mold core or external mold core parts are removed from the workpiece, but that elements introduced into the mold core or into the casting mold, such as cooling irons, are also removed.

Furthermore, it can be provided that the hammer head is pressed against the energy transfer surface during the process of smashing the mandrel in such a way that it is constantly in contact with the workpiece even if the energy transfer surface is shifted. In other words, this prevents the hammer head from lifting off the energy transfer surface of the workpiece during the process of shattering the mold core. This can prevent a blow from being exerted on the energy transfer surface of the workpiece and damaging it. The position of the energy transfer surface is shifted in particular when the workpiece is placed on the support table in such a way that an external mold core, which is smashed, rests on the support table. The position of the workpiece is shifted as a result of the shattering of the external mold core.

It can also be useful if the coring hammer is designed as a hydraulic hammer. The advantage here is that a hydraulic hammer can be controlled in such a way that the hammer head is constantly in contact with the energy transfer surface of the workpiece and there is no impact on the workpiece.

Furthermore, it can be provided that the hammer head is constantly pressed against the energy transfer surface of the workpiece with a contact pressure between 100N and 2000N, in particular between 200N and 700N, while the mold core is being smashed.

Furthermore, it can be provided that the workpiece is designed as a hollow cylindrical electric motor housing blank for further processing into an electric motor housing, an end face of the hollow cylindrical electric motor housing blank serving as the energy transfer surface. The advantage here is that the end face of the hollow cylindrical electric motor housing blank is subsequently mechanically reworked. In addition, the end face can have a comparatively high strength, since it can solidify earlier.

The mold core is preferably a structure that is formed from sand and after its removal from the workpiece, cavities or recesses can be formed in the workpiece. In particular, it can be provided that the sand of the mold core is given its dimensional stability by means of a binder. The mold core can consist of several parts which can be connected to one another or which can be arranged independently of one another at different points in the casting mold. Furthermore, it can be provided that the mold core is also partially arranged on the outside of the workpiece, or that the mold core partially protrudes outwardly beyond the workpiece. Such an external mold core can be arranged, for example, in the area of the feeder or the sprue.

The process step “shattering the mold core” is understood to mean a process step in which the mold core breaks at least partially. This process step does not include removing the mandrel from the workpiece.

A cylinder head blank is a cast workpiece from which a cylinder head for an internal combustion engine is manufactured through mechanical post-processing, such as milling. The finished cylinder head is placed on an engine block of the internal combustion engine. The cylinder head therefore has an engine block connection surface which, when installed, optionally rests against the cylinder block with the interposition of the cylinder head gasket. The surface that is used on the cylinder head blank as a raw surface for the engine block connection surface of the cylinder head is referred to as the engine block connection surface of the cylinder head blank. The cylinder head blank thus also has, by definition, an engine block connection surface, this first having to be mechanically processed in order to actually be brought into contact with the engine block.

The casting position of the workpiece is understood to mean that spatial orientation or position in which the workpiece lies as long as it is received in the casting mold. This applies to gravity casting processes in which the mold is not moved. In the case of tilt casting or rotation casting, the casting position is understood to be the end position of the casting mold.

For a better understanding of the invention, it is explained in more detail with reference to the following figures.

Fig. 1

ein Flussdiagramm eines Ausführungsbeispiels des Verfahrens zum Herstellen eines gegossenen Werkstücks;

Fig. 2

eine schematische Darstellung eines gegossenen Werkstücks mit Entkernhammer und Lastaufteilungsplatte;

Fig. 3

eine schematische Darstellung eines Zylinderkopfrohlings und eines Zylinderkopfes;

Fig. 4

ein Zylinderkopfrohling in einer Vorrichtung zum Entkernen;

Fig. 5

ein Flussdiagramm eines weiteren Ausführungsbeispiels des Verfahrens zum Herstellen eines gegossenen Werkstücks;

Fig. 6

ein weiteres Ausführungsbeispiel eines Werkstücks, welches als Gehäuse für einen Elektromotor ausgebildet ist.

They each show in a greatly simplified, schematic representation:

Fig. 1

a flow diagram of an embodiment of the method for producing a cast workpiece;

Fig. 2

a schematic representation of a cast workpiece with a coring hammer and load sharing plate;

Fig. 3

a schematic representation of a cylinder head blank and a cylinder head;

Fig. 4

a cylinder head blank in a coring apparatus;

Fig. 5

a flow chart of a further embodiment of the method for producing a cast workpiece;

Fig. 6

a further embodiment of a workpiece which is designed as a housing for an electric motor.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference symbols or the same component designations, it being possible for the disclosures contained in the entire description to be transferred accordingly to the same parts with the same reference symbols or the same component designations. The position details selected in the description, such as above, below, to the side, etc., also relate to the figure immediately described and shown and these position details are to be transferred accordingly to the new position in the event of a change in position.

According to Fig. 1 In a method according to the invention for producing a cast workpiece 1, a molten metal 2 is introduced into a casting mold 3, for example a mold. In the exemplary embodiment shown, the casting mold 3 is designed as a two-part casting mold 3 with a lower part 4 and an upper part 5, which are detachably connected to one another. Of course, the mold 3 can also have more than two parts.

Furthermore, it can be provided that a cooling channel 15 is formed in the casting mold 3, in particular in the lower part 4 or in the upper part 5, in which a cooling liquid is guided. As a result, the workpiece 1 can already be cooled in the casting mold 3 in order to accelerate the solidification process. In particular, it can be provided that the cooling channel 15 is formed at least in that region of the casting mold 3 in which an energy transfer surface 12 is to be provided on the workpiece 1.

A mold core 7 is inserted into the casting mold 3 and, together with the inner walls of the lower part 4 and the upper part 5, delimits a mold cavity 6. The metal melt 2, which is particularly preferably an aluminum melt, is introduced into the mold cavity 6. In principle, all known casting methods can be used as the method for introducing the molten metal. As particularly beneficial the process steps according to the invention have proven themselves in gravity die casting.

After the workpiece 1 has solidified, it can be removed from the casting mold 3. For this purpose, the lower part 4 and the upper part 5 can be moved apart and then the hot workpiece 1 can be removed from the casting mold 3.

In the case of undercut or complex workpieces 1, it can also be provided that the casting mold 3 consists of several parts.

At this point in time, the mold core 7 is still in a cavity of the workpiece 1, or the mold core 7 can be arranged on an outer surface of the workpiece 1, or can extend to an outer surface of the workpiece. The hot workpiece 1 is removed from the casting mold 3 at a surface temperature which is above 150 ° C. In particular, a surface temperature when the workpiece 1 is removed from the casting mold 3 can be over 300 ° C., in particular between 360 ° and 440 ° C. The workpiece 1 can be removed from the casting mold 3, for example, by means of an automated gripping unit 8.

The hot workpiece 1 removed from the casting mold 3 can optionally be cooled in a further step to a surface temperature which, depending on the removal temperature, is between 150 and 400 ° C. A mist 9 composed of water droplets can be used to cool the workpiece 1. The water droplets evaporate as soon as they strike a hot surface of the workpiece 1. Since the workpiece 1 is cooled in this step to a temperature which is well above the evaporation temperature of water, it is ensured that no water droplets can penetrate the mold core 7.

Instead of the mist 9 of water droplets, the workpiece 1 can also be immersed in an immersion bath to cool down.

At this point it should be pointed out again that the temperatures specified in this document relate to the surface temperatures of the workpiece 1.

The surface temperature of the workpiece 1 in the casting mold can be determined, for example, by means of temperature sensors fitted in or on the casting mold 3 and outside of the casting mold 3 also in a contactless manner by means of infrared sensors. In addition, other sensors and methods known to the person skilled in the art for determining the temperature can of course also be used. Alternatively, the surface temperature of the workpiece 1 can also be calculated as a mathematical model and calculated over the course of time.

The optional additional cooling of the workpiece 1 outside the casting mold 3 only takes place until it has reached the desired temperature in a range between 300 ° and 400 ° C.

Subsequent to the removal of the workpiece 1 from the casting mold 3 or also subsequent to the optional additional cooling of the workpiece 1 outside the casting mold 3, the mold core 7 can be shattered. Here, a hammer head 10 of a coring hammer 11 is applied to an energy transfer surface 12 of the workpiece 1. In particular, an effective surface 14 of the hammer head 10 rests against the energy transfer surface 12 of the workpiece 1. When shattered, the mold core 7 is broken, or at least provided with cracks.

The possible structure of a coring hammer 11 is shown in AT 513442 A1 described, wherein the coring hammer 11 is referred to in this document as a vibrating hammer.

How out Fig. 1 It is clearly evident that when the mold core 7 is smashed, the hammer head 10 of the coring hammer 11 rests on the energy transfer surface 12 of the workpiece 1. As a result, the energy applied by the hammer head 10 of the coring hammer 11 is introduced into the energy transfer surface 12 of the workpiece 1, causing the workpiece 1 to vibrate and the mold core 7 to be shattered.

Since the workpiece 1 has a high surface temperature during this process, the strength of the workpiece 1 has not yet been fully achieved at this point in time. To the The energy transfer surface 12 of the workpiece 1 is therefore subject to special requirements. In particular, it is necessary that the traces of action on the energy transfer surface 12 by the hammer head 10 are only so small that the finished workpiece 1 has no functional losses and / or no optical impairments. Several measures can be taken to achieve this.

For example, it can be provided that the energy transfer surface 12 used is a surface of the workpiece 1 which has a lower surface temperature than the remaining surfaces of the workpiece 1. As a result, the energy transfer surface 12 can have a higher strength than the remaining surfaces of the workpiece 1.

The lower temperature of the energy transfer surface 12 can be achieved, for example, in that the energy transfer surface 12 is arranged in the cast position on an underside 19 of the workpiece 1. This results from the fact that, due to gravity, the molten metal 2 hits the bottom of the casting mold 3 first and, in conventional casting processes in which the molten metal 2 is poured into the casting mold from above, is also heated less strongly by the newly poured molten metal 2. This area can thus cool down first and form the energy transfer surface 12.

Furthermore, it can be provided that, in order to smash the mold core 7, the workpiece 1 is turned upside down in comparison to the cast position, so that the workpiece 1 rests with one support side 20 on the support table 21. The support side 20 is formed opposite the energy transfer surface 12.

In a subsequent method step, it can be provided that the workpiece 1 is clamped in a vibrating device 13 and is set to vibrate, with the mold core 7 finally being smashed and removed from the workpiece 1. It can be provided here that the workpiece 1 is rotated in the vibrating device 13 about at least one horizontal axis of rotation 16 while vibrating at the same time. As a result, the broken individual parts of the mandrel 7 can be shaken out of the workpiece 1. In other words, this measure cores the workpiece 1.

The treatment of the workpiece 1 by means of the coring hammer 11 can precede the treatment of the workpiece 1 by means of the vibrating device 13, whereby the mold core 7 can initially be broken by means of the coring hammer 11 and broken into small pieces by means of the vibrating device 13, which are also in the Vibrating device 13 can be conveyed out of the workpiece 1.

A temperature which has proven to be particularly advantageous for the temperature at which the core of the workpiece 1 can be removed is a temperature which, with a deviation of +/- 30%, corresponds to a temperature at which precipitation hardening of a material of the workpiece 1 begins.

After the workpiece 1 has been cored, it can be immersed in a basin 18 filled with a cooling liquid 17 for further cooling.

Furthermore, it can be provided that the workpiece 1 is then mechanically processed in the area of the energy transfer surface 12. In particular, a cutting tool 22, for example a milling cutter, can be used to remove a layer of the energy transfer surface 12 and thus to generate a functional surface.

How out Fig. 2 It can be seen that it can be provided that a load sharing plate 23 is inserted between the hammer head 10 and the workpiece 1, by means of which the force applied by the hammer head 10 can be applied evenly to the energy transfer surface 12. As a result of this measure, the surface pressure on the energy transfer surface 12 can be kept as low as possible, so that the workpiece 1 is not destroyed by the action of the coring hammer 11.

In a further development it can also be provided that two or more coring hammers 11 act on the load sharing plate 23. In particular, it can be provided that the load sharing plate 23 is coupled directly to the hammer heads 10 of the individual coring hammers 11 and therefore does not have to be manipulated separately. This is particularly advantageous for series components.

Fig. 3 shows a schematic representation of a cylinder head blank 24 and a cylinder head 25 which is manufactured from the cylinder head blank 24 by mechanical processing.

In the Fig. 3 an engine block connection surface 26 of the cylinder head blank 24 is visible. In the installed state of the cylinder head 25, the engine block connection surface 26 faces the engine block of the internal combustion engine and in particular rests against the engine block of the internal combustion engine.

Fig. 4 shows a perspective view of a coring hammer carrier 27. The coring hammer carrier 27 can serve in particular for receiving or for the automated movement of one or more coring hammers 11. In particular, it can be provided that the coring hammers 11 are arranged on an upper slide 28 which can be displaced in the vertical direction, whereby the coring hammers 11 can be placed against the cylinder head blank 24. Furthermore, it can be provided that the coring hammer carrier 27 has a support table 21 on which the cylinder head blank 24 is placed. In addition, it can be provided that a buffer element 29, which is arranged between the cylinder head blank 24 and the support table 21, is arranged under the workpiece 1, in particular the cylinder head blank 24. The buffer element 29 can, as shown, be designed in the form of a strip. As an alternative to this, the buffer element 29 can also have a flat design, with recesses also being able to be provided in the buffer element 29, which are permeable to the broken mold core 7.

How out Fig. 4 Furthermore, it can be seen that the load distribution plate 23 is brought between the hammer head 10 and the workpiece 1 in order to reduce the surface pressure on the workpiece 1.

In particular, in the exemplary embodiment according to Fig. 4 it is provided that the load sharing plate 23 is coupled to two hammer heads 10 of two stripping hammers 11. Of course, a plurality of coring hammers 11 can also be provided to which the load sharing plate 23 is coupled. The coupling of the load sharing plate 23 to the hammer heads 10 of the coring hammers 11 can be done, for example, via a releasable coupling.

As if from a synopsis of the Figures 3 and 4th As can be seen, it can be provided that the engine block connection surface 26 of the cylinder head blank 24 serves as an energy transfer surface 12. After the casting process, the cylinder head blank 24 can be arranged in the casting mold 3 in such a way that the engine block connection surface 26 is arranged in the cast position on the underside 19 of the cylinder head blank 24.

Fig. 5 FIG. 4 shows a flow diagram of a further possible method sequence for producing a cast workpiece 1.

How out Fig. 5 As can be seen, it can be provided that the workpiece 1 is cast after the casting mold 3 has been prepared.

The workpiece 1 can then be removed from the casting mold 3, in particular by means of the gripping unit 8. The removal from the casting mold 3 can take place as soon as the workpiece 1 has a surface temperature in the range of 430 ° C. on the energy transfer surface 12. During the manipulation of the workpiece 1, it cools down further, so that the surface temperature on the energy transfer surface 12 at the end of the handling process is approximately 400 ° C. or below.

At this surface temperature of below 400 ° C., in particular below 360 ° C., the hammer head 10 of the coring hammer 11 can be placed on the energy transfer surface 12 and hammered onto it. After a period of 1 to 20 seconds. at least the outer parts of the mold core 7 break off, so that the surface of the workpiece 1 is exposed and the workpiece 1 can now cool down more quickly.

In a subsequent optional process step, the workpiece 1, in particular the energy transfer surface 12 of the workpiece 1, can be immersed in an immersion bath in order to quench it and cool it down further.

In a subsequent process step, the workpiece 1 can be stored in a refrigerated shelf until the surface temperature of the energy transfer surface 12 of the workpiece 1 is between 150.degree. C. and 200.degree.

Subsequently, the workpiece 1 can again be applied to the energy transfer surface by the hammer head 10 of a coring hammer 11 in order to smash the remaining parts of the mold core 7.

The workpiece 1 can then be clamped in the vibrating device 13 in order to further shatter the mold core 7 and thereby remove it from the workpiece 1.

The workpiece 1 can then optionally be further cooled and mechanically processed.

Fig. 6 shows a further embodiment of a workpiece 1, which is designed as a hollow cylindrical electric motor housing blank 30 for further processing into an electric motor housing for an electric motor. As can be seen from this exemplary embodiment, it can be provided that the energy transfer surface 12 is formed on an end surface 31 of the hollow-cylindrical electric motor housing blank 30.

It can be provided here that the mold core 7 is partially designed as an external core. In addition, the mold core 7 can form the cavity of the electric motor housing blank 30. Furthermore, it can be provided that an internal mold core 7 is formed in the wall of the electric motor housing blank 30, which is used to form cooling water channels in the electric motor housing.

In particular, it can be provided that the electric motor housing blank 30 is designed as an essentially rotationally symmetrical hollow body. In addition, it can be provided that the end face 31 of the hollow cylindrical electric motor housing blank 30 is machined in a further work step.

The exemplary embodiments show possible design variants, whereby it should be noted at this point that the invention is not limited to the specifically illustrated design variants of the same, but rather various combinations of the individual design variants with one another are possible and this possibility of variation is based on the teaching on technical action by the present invention Ability of the person skilled in this technical field.

The scope of protection is determined by the claims. However, the description and the drawings are to be used to interpret the claims. Individual features or combinations of features from the different exemplary embodiments shown and described can represent independent inventive solutions. The task on which the independent inventive solutions are based can be found in the description.

All information on value ranges in the present description are to be understood in such a way that they include any and all sub-areas thereof, e.g. the information 1 to 10 is to be understood in such a way that all sub-areas, starting from the lower limit 1 and the upper limit 10, are also included , ie all sub-ranges begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, for example 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

For the sake of clarity, it should finally be pointed out that, for a better understanding of the structure, some elements have been shown not to scale and / or enlarged and / or reduced.

List of reference symbols

1 workpiece 31 Face 2 Molten metal 3 mold 4th Lower part 5 Top 6th cavity 7th Mold core 8th Gripping unit 9 fog 10 Hammer head 11 Coring hammer 12th Energy transfer surface 13th Vibrator 14th Impact area hammer head 15th Cooling duct 16 Axis of rotation 17th Coolant 18th pool 19th bottom 20th Circulation page 21st Support table 22nd Cutting tool 23 Load sharing plate 24 Cylinder head blank 25th Cylinder head 26th Engine block connection surface 27 Coring hammer carrier 28 Top slide 29 Buffer element 30th Electric motor housing blank

Claims (21)

1. A method for producing a cast workpiece (1), wherein the method comprises the following method steps:

   - providing a mold (3) having at least one mold core (7) arranged in the mold (3);

   - inserting a metal melt (2) into the mold (3);

   - waiting for a period of time until at least the outer contour of the metal melt (2) has solidified and the workpiece (1) has been formed from the metal melt (2);

   - removing the workpiece (1) from the mold (3);

   - shattering the mold core (7), wherein for shattering the mold core (7), a hammer head (10) is applied on a defined energy transmission surface (12) of the workpiece (1) and the energy transmission surface (12) is acted on by means of the hammer head (10), characterized in that

   shattering the mold core (7) by means of the hammer head (10) is carried out at a surface temperature of the energy transmission surface (12) of between 300° Celsius and 400° Celsius, wherein at least outward parts of the mold core (7) are shattered.
2. The method according to claim 1, characterized in that the energy transmission surface (12) is a surface of the workpiece (1) which is mechanically processed, in particular chipped, in subsequent production steps.
3. The method according to claim 1 or 2, characterized in that a surface of the workpiece (1) serves as the energy transmission surface (12) which has the largest surface solidity at the point in time at which the mold core (7) is shattered.
4. The method according to one of the preceding claims, characterized in that a surface of the workpiece (1) serves as the energy transmission surface (12), which surface was arranged in the region of a lower part (4) of the mold (3), in particular at a bottom side (19) of the workpiece (1) with respect to the casting position, during the casting process.
5. The method according to claim 4, characterized in that the workpiece (1) is turned by 180° after removal from the mold (3) such that the energy transmission surface (12) is located on the upper side of the workpiece (1) and the workpiece (1) rests on a support table (21) on a support side (20) opposite to the energy transmission surface (12).
6. The method according to one of the preceding claims, characterized in that the workpiece (1) is designed as a cylinder head blank (24) for further processing into a cylinder head (25) for a combustion engine, wherein an engine block connecting surface (26) of the cylinder head blank (24) serves as the energy transmission surface (12).
7. The method according to one of the preceding claims, characterized in that the energy transmission surface (12) is formed as a planar surface.
8. The method according to one of the preceding claims, characterized in that a surface area of an application surface (14) of the hammer head (10) or of the load distribution plate (23), which rests against the energy transmission surface (12) during shattering of the mold core (7), amounts to between 150% and 10%, in particular between 110% and 50%, preferably between 100% and 80%, of a surface area of the energy transmission surface (12).
9. The method according to one of the preceding claims, characterized in that the workpiece (1) is removed from the mold (3) at a surface temperature of the energy transmission surface (12) of between 440° Celsius and 360° Celsius.
10. The method according to claim 9, characterized in that the workpiece (1) is further cooled down in the ambiance while the workpiece (1) is fed to a hammer head (10) for shattering the mold core (7) until the energy transmission surface (12) has a surface temperature of between 300° Celsius and 400° Celsius.
11. The method according to one of the preceding claims, characterized in that the hammer head (10) acts on the workpiece (1) with a striking action for between 1 second and 20 seconds.
12. The method according to one of the preceding claims, characterized in that after shattering at least of parts of the mold core (7), the workpiece (1) is further cooled down until the energy transmission surface (12) has a surface temperature of between 100° Celsius and 200° Celsius, in particular between 150° Celsius and 200° Celsius, and that the workpiece (1) is subsequently again fed to a hammer head (10) for shattering of the mold core (7), wherein in the course of this, the remaining parts, in particular the parts located on the inside of the workpiece (1), of the mold core (7) are shattered as well.
13. The method according to one of the preceding claims, characterized in that the workpiece (1) is clamped in a vibrator device (13) after shattering of the mold core (7) and the workpiece (1) is rotated about at least one horizontal axis of rotation (16) during simultaneous vibration.
14. The method according to one of the preceding claims, characterized in that during shattering of the mold core (7), multiple hammer heads (10) simultaneously act on the energy transmission surface (12).
15. The method according to one of the preceding claims, characterized in that a load distribution plate (23) is inserted between the hammer head (10) and the energy transmission surface (12).
16. The method according to one of the preceding claims, characterized in that a cooling channel (15) is formed in the mold (3), at least in the region in which the energy transmission surface (12) of the workpiece (1) is formed, wherein the workpiece (1) is cooled in the region of the energy transmission surface (12) by means of the cooling channel (15).
17. The method according to one of the preceding claims, characterized in that the energy transmission surface (12) is locally cooled down after removal of the workpiece (1) from the mold (3), for example by the energy transmission surface (12) of the workpiece (1) being plunged into a coolant.
18. The method according to one of the preceding claims, characterized in that the feeder of the workpiece (1) comprises the energy transmission surface (12).
19. The method according to one of the preceding claims, characterized in that the hammer head (10) is pressed against the energy transmission surface (12) during the process of shattering the mold core (7) such that it continuously rests against the energy transmission surface (12) of the workpiece (1) also in case of a positional displacement.
20. The method according to one of the preceding claims, characterized in that during shattering of the mold core (7), the hammer head (10) is constantly pressed against the energy transmission surface (12) of the workpiece (1) with a pressure force between 100N and 2,000N, in particular between 200N and 700N.
21. The method according to one of the preceding claims, characterized in that the workpiece (1) is formed as a hollow-cylindrical electric motor housing blank (30) for further processing to an electric motor housing, wherein an end face (31) of the hollow-cylindrical electric motor housing blank (30) serves as the energy transmission surface (12).

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