Method for producing a die for an aluminum casting process

Abstract

The invention relates to a method for producing a die (1) for an aluminum casting process, which die (1) at least partly delimits a cavity (3) designed to receive liquid aluminum during the aluminum casting process, in which method a main body (2) of the die (1) is provided, said main body being made of a main-body material, and at least one reinforcing layer (6), which delimits the cavity (3) and is made of a reinforcing material that differs from the main-body material, is additively built on at least one portion (5, 14-16) of the main body (2) by means of an additive manufacturing method.

Description

[0001] Method for producing a casting mold for an aluminum casting process

[0002] The invention relates to methods for producing a casting mold for an aluminum casting process, which casting mold at least partially delimits a cavity designed to receive liquid aluminum during the aluminum casting process.

[0003] Methods for producing casting molds that can be used in an aluminum casting process to define a cavity into which liquid or molten aluminum is poured are generally known from the prior art. Such casting molds are usually produced from a material, such as a low-alloy or high-alloy steel, using subtractive manufacturing processes, such as milling. It is well known that the casting mold has an abrasive effect during the casting process, so that the liquid aluminum erodes the casting mold, both chemically and mechanically. In other words, the casting mold wears out with the increasing number of casting processes in which it is used, making regular maintenance or replacement of the mold necessary. For example, the casting mold must be checked at regular intervals or.must be repaired or maintained after a defined number of processes in order to ensure the quality of the components obtained through the process.

[0004] Although the use of other materials to provide a casting mold is known from the prior art, which are more resistant, particularly chemically, to the liquid aluminum in the aluminum casting process, it is also known that such materials and their processing into the casting mold are significantly more complex.

[0005] The invention is based on the object of providing an improved method for producing a casting mold for an aluminum casting process, in which the casting mold has a longer service life and the effort for producing the casting mold is reduced.

[0006] The object is achieved by a method according to claim 1. The dependent claims relate to possible embodiments. As described, the invention relates to a method for producing a casting mold for an aluminum casting process, which casting mold at least partially delimits a cavity designed to receive liquid aluminum during the aluminum casting process. In other words, the liquid or molten aluminum in the aluminum process is introduced or poured into the cavity, which is at least partially delimited by the casting mold. The casting mold produced by the method can in principle be used for any aluminum process, including in particular die casting, gravity casting, low-pressure casting, injection casting, lost mold, as well as all sub-processes of such casting processes or related or modified forms of such casting processes.The aluminum casting process described herein also applies to any mixtures and alloys containing or comprising aluminum. The casting mold may specifically form or comprise a tool.

[0007] The invention is based on the finding that a base body of the casting mold is provided from a base body material and, on at least one section of the base body, at least one armor layer bounding the cavity is additively built up from an armor material different from the base body material using an additive manufacturing process. Without the armor layer, the section of the base body would bound the cavity and is thus covered or masked by the armor layer in the direction of the cavity. Advantageously, the additive manufacturing process can be used to apply the armor layer in a targeted manner to at least one section of the base body. As described, the armor layer is additively built up from the armor material, which armor material is more resistant than the base body material in the process in which the casting mold is used.Therefore, it is not necessary to manufacture the entire casting mold from the armor material. Instead, it is possible to form a large part of the casting mold, namely the base body, from the comparatively simpler and less complex base body material, and to manufacture only the armor layer from the armor material. The armor material can optionally be referred to as "reinforcement material" and the armor layer as "reinforcement layer." This advantageously makes it possible to achieve a longer service life or higher or longer repair or maintenance intervals compared to a casting mold made exclusively from the base body material. Compared to forming the entire casting mold from the armor material, a less complex manufacturing process is provided, particularly in terms of production and cost.

[0008] The additive construction of the at least one armor layer, which is intended to delimit the cavity and is built up on the base body material of the base body, can in principle be carried out by any desired additive manufacturing process. Purely by way of example, the additive construction can be carried out by laser beam melting, laser beam sintering, laser powder deposition welding, wire arc deposition or any other desired additive manufacturing processes. In other words, the present invention proposes a combination of two manufacturing processes, which can in particular be referred to as “hybrid manufacturing” and which combines, for example, the production of the base body by a conventional manufacturing process, that is to say in particular a subtractive process, and the production of the armor layer by an additive manufacturing process. The base body of the casting mold, which consists of the base body material orThis layer, in particular, provides the majority of the casting mold, for example, in terms of its volume or mass. Single or multiple layers, in particular a defined number of layers, of typical layer thicknesses for additive manufacturing can be built up as an armor layer. The exact layer thickness as well as the total thickness depends on the casting process to be performed and can be selected or adjusted accordingly.

[0009] As described, the at least one armor layer can be additively built up on any portion of the base body of the casting mold, thus defining the cavity in this area. In other words, the armor layer, when built up, can be arranged between the cavity and the base body material arranged beneath the armor layer to protect the base body material from contact with the aluminum cast into the cavity.

[0010] Specifically, the method can provide for the at least one armor layer to be applied to at least one locally limited section of the base body. For example, multiple armor layers can be selectively applied to the base body material in locally limited sections of the base body, for example, at different locations on the base body. Thus, armor layers can be applied in a targeted manner, particularly in areas of the casting mold exposed to increased wear, in order to protect the base body material there. Accordingly, the armor layer can be applied locally only where this is necessary or advantageous for increasing service life.In summary, the comparatively inexpensive and easy-to-produce base body material can be used in all areas of the casting mold that are not subject to increased wear, and the armor layer can be used where necessary, resulting in a casting mold that is less complex to produce and achieves the longest possible service life. Within the scope of the process, it is possible to build up a single armor layer or a specific number of armor layers, thus "coating" the underlying base body. Likewise, a multitude of armor layers can be built up, resulting in a volume area formed by armor layers, which can be thicker, stronger, or higher than the underlying base body.

[0011] According to one embodiment of the method, the at least one locally delimited section on which the at least one armor layer is additively built up can be determined based on a simulation and / or based on process-related removal of the casting mold, in particular based on determined wear and / or abrasion and / or force acting during the process and / or turbulence occurring in the casting material during the process and / or based on a function of the section or a geometry of the section. In other words, that locally delimited section of the casting mold in which increased wear is to be expected during the process or in which increased wear occurs or has occurred can be reinforced by the at least one armor layer.

[0012] Wear can be determined, for example, by simulating the casting process, whereby at least one section can be identified that is subjected to more abrasive, i.e., mechanical and / or chemical, wear by the casting material than at least one other section of the casting mold. It is also possible to determine the at least one section from the casting process itself, for example, to determine which sections exhibit which degree of wear after a certain number of casting processes.

[0013] For example, the at least one locally limited section can also be determined based on forces acting during the process that are transferred from the casting material to the casting mold or based on turbulence occurring in the casting material during the process. The higher the forces between the casting material and the casting mold, for example at points where the melt is redirected or where the flow conditions are changed by cross-sectional changes in the cavity, or the stronger the turbulence in the casting material, the more increased material removal or wear will occur in that section of the casting mold. Likewise, the at least one local section to which the armor layer is to be applied can be determined based on its function or geometry. It has been shown that, for example, increased wear can occur depending on the curvature and filling flows of the section of the casting mold.Likewise, sections that perform different functions in the casting process, such as inlet sections, deflection sections, cross-sectional changes and the like, can be reinforced or protected by the armor layer, as these usually show increased wear.

[0014] The method can further be developed such that the armor material is chemically resistant to the cast material, in particular has a higher chemical resistance to the cast material than the base body material. As described, aluminum is used as the cast material, so that the armor material is more chemically resistant to molten aluminum than the base body material according to the described embodiment. This can ensure that the wear effect caused by chemical reactions in the section to which the armor material is applied, i.e. on the armor section, is reduced compared to an otherwise unprotected area of ​​the base body. In other words, the armor layer shows no or a significantly lower chemical reaction upon contact with the cast material, in particular compared to the base body material.Furthermore, the method can provide for the base body material to be softer, in particular in a range <60 HRC, than the armor material, in particular in a range >60 HRC, and / or for the armor material to have a defined thermal expansion and thermal conductivity. Because the armor material is harder than the base body material, the mechanical wear on the armor material or the armor layer is reduced compared to an otherwise unprotected surface of the base body. Furthermore, the defined thermal expansion and thermal conductivity of the armor material allows the casting process to be carried out in compliance with specified boundary conditions. In particular, the armor layer has sufficient thermal conductivity to ensure heat conduction between the remaining casting mold and the casting material during the casting process.

[0015] Furthermore, the method can provide for the base body material to be made from a steel, in particular a low-alloy or high-alloy steel, and / or for the armouring layer to be made from or to comprise a hard metal, heavy metal or refractory metal, in particular tungsten. As already described in the introduction, the base body of the casting mould can be obtained from a conventional manufacturing process, for example by milling. Steel can be used for the base body material, in particular a low-alloy or high-alloy steel. A hard metal, a heavy metal or refractory metal, for example tungsten, can in principle be used to form the armouring layer, i.e. as armouring material. Furthermore, compounds, for example titanium nitride, orAlloys or mixtures comprising such a hard metal or heavy metal or refractory metal are used, for example tungsten carbide-cobalt, a tungsten alloy or pure tungsten.

[0016] As described above, a base body of the casting mold is generally provided, onto which the armor layer is additively built up in at least one section. In a further embodiment of the method, it can be provided that, in particular by means of a detection device, one or more condition parameters of the casting mold, in particular of the at least one section and / or the at least one armor layer, are detected and the at least one armor layer is built up depending on the condition parameter(s). The condition parameter(s) can, for example, generally describe a condition of the section of the casting mold or of the armor layer, in particular the extent to which it is intact or corresponds to a desired geometry and material properties.

[0017] For example, the condition parameter(s) can be used to determine whether the section of the casting mold to which the armor layer is to be applied corresponds to the target condition. It can also be determined whether the casting mold has any wear that needs to be repaired. For example, the level of wear of a previously applied armor layer can be determined and, accordingly, the extent to which the armor layer needs to be rebuilt can be determined. In other words, a manufacturing process can generally be carried out in which the armor layer is built up on the base body of the casting mold. A modification, i.e. in particular a repair or maintenance, can also be carried out in which either part of the base body is replaced by the armor layer and the armor layer is built up on top of it, or a previously applied armor layer is repaired.In particular, it is also possible to retrofit an armor layer to a casting mold that previously did not have one. For example, the condition parameter(s) can be recorded optically or tactilely by determining at least one actual dimension of the casting mold and comparing it with at least one target dimension. Accordingly, it can be determined which topology the armor layer must have and how it should be applied to achieve the target dimension.

[0018] Based on the condition parameter described above, at least a portion of an armor layer, in particular a previously applied one, and / or at least a portion of the casting mold can be removed. If, for example, the casting mold shows wear in the area of ​​a previously applied armor layer, it is possible to partially remove this so that a defined rebuild of the armor layer can be carried out on the previously applied armor layer or an exposed portion of the armor layer. Likewise, any other casting mold can be provided, wherein a portion of the casting mold can be removed, i.e., the base body, so that a defined armor layer can subsequently be applied thereon, for example by replacing the areas of the casting mold previously formed there. In other words, the armor layer can also be retrofitted to a casting mold that previously did not comprise an armor layer.The defined removal of at least a portion of the armor layer or the casting mold can, in principle, be performed in any desired manner, in particular mechanically, for example by milling, grinding, or by erosion, ablation, or other abrasive processes. In particular, by removing at least a portion of the casting mold or the armor layer, the casting mold can be prepared in such a way that a defined (re)construction of the armor layer can take place.

[0019] In addition to the method, the invention relates to a casting mold for an aluminum casting process, which is produced in particular according to the method described above, which casting mold is designed to delimit at least in sections a cavity for receiving liquid aluminum during the aluminum casting process, wherein the casting mold has a base body produced from a base body material and at least one armor layer delimiting the cavity on at least one section of the base body, which armor layer is constructed by means of an additive manufacturing process from an armor material different from the base body material.

[0020] Furthermore, the invention relates to a method for producing a cast component by means of a casting mold, comprising the steps:

[0021] Providing a previously described casting mold, in particular a casting mold produced by the previously described method;

[0022] Pouring aluminum into a cavity defined by the mold.

[0023] In other words, the method described above can be used to produce or modify a casting mold that can subsequently be used in a casting process, particularly an aluminum casting process. Advantageously, the produced armor layer protects the underlying base material from contact with the casting material, particularly the aluminum, thus extending the service life of the casting mold. All advantages, details, designs, and / or features described with regard to the method for producing the casting mold are fully applicable to the casting mold and the method for producing a cast component.

[0024] The invention is explained using exemplary embodiments with reference to the figures. The figures are schematic representations and show:

[0025] Fig. 1 is a schematic diagram of a method for producing a casting mold for an aluminum casting process according to an embodiment;

[0026] Fig. 2 is a schematic diagram of a flow chart of a method for producing a casting mold for an aluminum casting process according to an embodiment; and

[0027] Fig. 3 a schematic diagram of a section of a casting mold for an aluminum casting process.

[0028] Fig. 1 schematically shows a situation during a method for producing a casting mold 1 for an aluminum casting process. The casting mold 1 has a base body 2 made of a base body material, for example steel, in particular low-alloy or high-alloy steel. The base body 2 shown as an example can represent a tool half of a casting mold 1, which, as shown for example in Fig. 3, can be supplemented by another tool half to delimit a cavity 3. The casting material or the melt, in particular liquid or molten aluminum, is introduced into the cavity 3 during the execution of the process for which the casting mold 1 can be used.

[0029] The casting mold 1 has a first section 4, at which the base body 2 delimits the cavity 3. Furthermore, two second sections 5 are shown purely by way of example. The design of the individual sections 4, 5 can be chosen or implemented as desired and is only used for illustrative purposes below. During the manufacturing process shown schematically in Fig. 1, the base body 2 is provided which, as already described, is made from a base body material. The base body 2 can be manufactured, for example, using conventional manufacturing processes, in particular milling. By way of example, an armor layer 6 is additively built up in each of the sections 5 of the casting mold 1, which armor layer consists of or comprises an armor material that is different from the base body material. The armor layer 6 can comprise several plies or layers.In other words, the casting mold 1 delimits the cavity 3 in the section 4 with the base body 2 and in the sections 5 by means of the armor layers 6 arranged there. The built-up armor layers 6 protect the underlying surface of the base body 2 or the base body material arranged there in the areas 5 from contact with the melt, in particular the molten aluminum.

[0030] The application of the armor layer 6 locally in the sections 5, i.e., selectively and locally limited, can be carried out by any suitable additive manufacturing process, for example, laser beam melting, laser beam sintering, wire-arc deposition, and the like. Purely by way of example, an additive manufacturing device 7 is shown, which is designed for the selective, layer-by-layer application of the armor layer 6 to the base body 2, for example, by melting applied armor material in section 5 using an energy beam or laser beam. Depending on which additive manufacturing process is used, the manufacturing device 7 must be adapted accordingly.

[0031] As described, the armor material from which the armor layer 6 is formed is made of a different material than the base body material of the base body 2 of the casting mold 1. In particular, the armor material is more chemically resistant to the melt, i.e., the molten aluminum, than the base body material. For example, no chemical reaction or a significantly lower chemical reaction takes place between the armor material and the melt. In particular, the armor material is harder than the base body material, so that the base body material is correspondingly softer than the armor material. The base body material can have a hardness in the range of less than 60 HRC, for example, between 55 and 58 HRC. In contrast, the armor material can have a hardness in a range of >60 HRC.For example, the armor material is formed from or comprises a hard metal, heavy metal, or refractory metal. The armor material may, for example, comprise tungsten, titanium nitride, tungsten carbide-cobalt, or other alloys, mixtures, or compounds containing such hard metals, heavy metals, or refractory metals.

[0032] To ensure the aluminum casting process can be carried out in a defined manner, the armor material exhibits a defined thermal expansion and thermal conductivity. The thermal conductivity of the armor material of the armor layers 6 is particularly sufficient to allow heat dissipation from the melt via the base body 2. The thermal expansion is designed to ensure sufficient durability and tool and process stability.

[0033] For example, the method schematically depicted in one method step in Fig. 1 can be executed based on the flowchart schematically depicted in Fig. 2. The method can start in a block 8, in which the base body 2 is provided. As already described, the base body 2 can consist of a steel or comprise steel and be provided by a conventional manufacturing process, for example, by milling.

[0034] Optionally, a state parameter of the base body 2 can be recorded in a block 9, for example, optically. The state parameter describes, for example, the state of the base body 2, in particular its topology or geometric information of the base body 2. The base body 2 can be, for example, a new tool component or mold component, a tool component or mold component to be repaired or maintained, or a tool component or mold component to be retrofitted. For the sake of simplicity, the tool component or mold component is referred to below as a "tool part." Parts manufactured with the mold 1 can be referred to as "components." A "tool part" or a "tool component" can therefore refer to a component of the tool, i.e., the mold 1, for example, a contour insert of the tool or mold 1.A "component" can then be defined as the product produced using the casting mold 1 in a casting process, for example, a body part for a motor vehicle. If the base body 2 provided in block 8 relates to a new tool part, recording the condition parameter in block 9 may not be necessary, since in this case the geometric details of the base body 2 are available. If an armor layer 6 on the base body 2 is to be retrofitted or repaired, its condition can be determined by recording the condition parameter in block 9, for example, how far the wear of the armor layer 6 or the base body 2 has progressed.

[0035] Further optionally, based on the previously determined condition parameter in block 10, a removal can be determined or a removal can take place. In other words, at least a portion of a previously applied armor layer 6 and / or at least a portion of the base body 2 can be removed in a defined manner in order to subsequently build up or rebuild the armor layer 6 in an improved manner. If the base body 2 is a new tool part, the described removal is not necessary and is therefore to be understood as optional. The final geometry of the base body 2 and armor layer 6 corresponds to the original target geometry of the casting mold 1, i.e., the base body 2 is reduced to such an extent that the armor layer 6 applied thereto reaches the target dimension. The armor layer 6 can be applied to the base body 2 (cf. Fig. 1 in the left-hand area) or "countersunk" (cf. Fig.1 in the right-hand area) is introduced into the base body 2 so that the final geometry of the tool contour or the casting mold 1 is not altered by the armor layer 6. As a rule, an "offset" can be introduced into the base body 1, and the required final geometry can thus be achieved with the thickness of the applied armor layer 6.

[0036] In any case, it can then be determined in block 11 in which sections 5 the armor layer 6 is to be built, repaired, or retrofitted. Subsequently, in block 12, the armor layer 6 can be built up in sections 5 using the additive manufacturing process, and thus the casting mold 1 can be manufactured, repaired, or retrofitted with the armor layer 6.

[0037] A purely exemplary casting mold 1 is shown in a sectional view in Fig. 3. The casting mold 1 accordingly has two tool halves, each having a base body 2 and, by way of example, armor layers 6 applied thereto. The shape of the casting mold 1 and the arrangement of the individual armor layers 6 are arbitrary and serve only for illustration purposes. As schematically shown by arrows 13, a melt is introduced into the cavity 3 in the aluminum casting process.

[0038] The determination of which sections 5, 14-16 each have an armor layer 6 to be applied, which was previously described, for example, with reference to block 11, can be determined, as represented by a first armor layer 6, for a section 14 based on the function of section 14. Section 14 can be an inlet section through which the melt can flow into the cavity 3. In this area, high turbulence is usually to be expected within the casting material or the melt, so that it is advisable to build up the armor layer 6 there in order to protect the underlying base body material.

[0039] A further section 15 has a deflection section and / or a cross-sectional change formed within the cavity 3 or the casting mold 1, such that comparatively high forces and turbulence are also transferred from the melt to the casting mold 1. Therefore, the implementation of an armor layer 6 is also specified in section 15. Furthermore, a section 16 shows an area of ​​the cavity 3 in which high turbulence is to be expected, such that a corresponding armor layer 6 is also built up there. As can be seen from the exemplary casting mold 1 in Fig. 3, it can be determined, for example by means of simulation or based on a wear pattern of a casting mold 1 used in a casting process, in which areas increased wear on the casting mold 1 occurs, so that these areas can be reinforced by corresponding armor layers 6.

[0040] The advantages, details, and features shown in the individual embodiments can be combined with one another as desired, are interchangeable, and are transferable to one another.

[0041] 1 mold

[0042] 2 Base body 3 Cavity

[0043] 4, 5 Section

[0044] 6 Armor layer

[0045] 7 Manufacturing device

[0046] 8-12 Block 13 Arrow

[0047] Section 14-16

Claims

CLAIMS 1. Method for producing a casting mold (1) for an aluminum casting process, which casting mold (1) delimits at least in sections a cavity (3) designed to receive liquid aluminum during the aluminum casting process, characterized in that a base body (2) of the casting mold (1) is provided from a base body material and on at least one section (5, 14-16) of the base body (2) at least one armor layer (6) delimiting the cavity (3) is additively built up from an armor material different from the base body material by means of an additive manufacturing process.

2. Method according to claim 1, characterized in that the at least one armor layer (6) is built up on at least one locally limited section (5, 14-16) of the base body (2).

3. Method according to claim 2, characterized in that the at least one locally limited section (5, 14-16) is determined based on a simulation and / or based on a process-related removal of the casting mold (1), in particular based on wear and / or abrasion and / or force acting in the process and / or turbulence occurring in the casting material and / or based on a function of the section (5, 14-16) and / or a geometry of the section (5, 14-16).

4. Method according to one of the preceding claims, characterized in that the armor material is chemically resistant to the cast material, in particular has a higher chemical resistance to the cast material than the base body material.

5. Method according to one of the preceding claims, characterized in that the base body material is softer, in particular in a range < 60HRC, than the armor material, in particular in a range > 60HRC, and / or that the armor material has a defined thermal expansion and thermal conductivity.

6. Method according to one of the preceding claims, characterized in that the base body material is made of a steel, in particular low-alloy or high-alloy, and / or the armor layer (6) is made of or comprises a hard metal or heavy metal or refractory metal, in particular tungsten.

7. Method according to one of the preceding claims, characterized in that, in particular by means of a detection device, at least one state parameter of the casting mold (1), in particular of the at least one section (5, 14-16) and / or of the at least one armor layer (6), is detected and the at least one armor layer (6) is built up as a function of the at least one state parameter.

8. The method according to claim 7, characterized in that based on the at least one state parameter, at least a part of an armour layer (6), in particular a previously built-up one, and / or at least a part of the casting mould (1) is removed.

9. Casting mold (1) for an aluminum casting process, in particular produced according to one of the preceding claims, which casting mold (1) is designed to delimit at least in sections a cavity for receiving liquid aluminum during the aluminum casting process, characterized in that the casting mold (1) has a base body (2) produced from a base body material and at least one armor layer (6) delimiting the cavity (3) on at least one section (5, 14-16) of the base body (2), which armor layer is constructed by means of an additive manufacturing process from an armor material different from the base body material.

10. Method for producing a cast component using a casting mold (1), comprising the steps: Providing a casting mold (1) according to the preceding claim; pouring aluminum into a cavity (3) defined by the casting mold (1).

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