Method for manufacturing a casting mold for an aluminum casting process

Abstract

The invention relates to a method for producing a casting mold (1) for an aluminum casting process, which at least partially bounds a mold cavity (3) designed to receive liquid aluminum during an aluminum casting process, wherein a base body (2) of the casting mold (1) is provided made of a base body material, and at least one armor layer (6) bounding the mold cavity (3) is additively built up on at least one section (5, 14-16) of the base body (2) from an armor material different from the base body material.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a casting mold for an aluminum casting process, the casting mold at least partially defining a cavity designed to receive liquid aluminum during the aluminum casting process. Background Technology

[0002] Methods for manufacturing casting molds that define cavities into which liquid or molten aluminum can be poured, suitable for use in aluminum casting processes, are known in principle from the prior art. Typically, such casting molds are made from a single material, such as low-alloy steel or high-alloy steel, by a subtractive manufacturing method (e.g., milling). It is well known that casting molds undergo abrasive action during the casting process, whereby molten aluminum erodes the mold both chemically and mechanically. In other words, the casting mold wears down with each casting process using it, thus requiring periodic maintenance or replacement. For example, it may be necessary to repair or maintain the casting mold at regular intervals or after a defined number of processes to ensure the quality of the parts obtained through the process.

[0003] Although it is known from the prior art to use other materials to provide casting molds, which have a greater chemical resistance to liquid aluminum in aluminum casting processes, it is also known that such materials and their processing into casting molds are much more complex. Summary of the Invention

[0004] The objective of this invention is to provide an improved method for manufacturing casting molds for aluminum casting processes, in which the casting molds have a longer service life or the cost of manufacturing the casting molds is reduced.

[0005] The above-described task is solved by the method according to claim 1. The related dependent claims relate to possible implementations.

[0006] As described above, the present invention relates to a method for manufacturing a casting mold for an aluminum casting process, the casting mold at least partially defining a cavity designed to receive molten aluminum during the aluminum casting process. In other words, in the aluminum casting process, molten or liquid aluminum is introduced or filled into a cavity at least partially defined by the casting mold. The casting mold manufactured by this method can, in principle, be used for any aluminum casting process, particularly including die casting, gravity casting, low-pressure casting, injection molding, lost foam casting, and all sub-processes of such casting processes or similar or modified forms of such casting processes. The aluminum casting processes described herein also relate to any mixtures and alloys containing or including aluminum. The casting mold can, in particular, form or include a tool.

[0007] The present invention is based on the understanding that the matrix of a casting mold is provided with a matrix material, and that at least one armor layer defining a cavity is additively constructed on at least one section of the matrix using an armor material different from the matrix material through an additive manufacturing method. Without the armor layer, the section of the matrix would define the cavity, and therefore the section toward the cavity would be covered or obscured by the armor layer. Advantageously, the additive manufacturing method can be used to selectively coat the armor layer onto said at least one section of the matrix. As described, the armor layer is additively constructed from an armor material that has higher durability than the matrix material during the use of the casting mold. Therefore, instead of manufacturing the entire casting mold from the armor material, the majority of the casting mold, i.e., the matrix, can be made from a matrix material that is relatively simpler or less expensive, and only the armor layer can be made from the armor material. The armor material may also be optionally referred to as a "reinforcing material," and the armor layer as a "reinforcing layer." Therefore, compared to casting molds made solely from the matrix material, it is advantageous to achieve a longer service life or a higher or longer repair or maintenance cycle. Compared to forming the entire casting mold from armor material, it provides a manufacturing process that is particularly less complex in terms of manufacturing technology and cost.

[0008] The additive construction of the at least one armor layer, which should be confined within a cavity and built on a matrix material of a substrate, can in principle be performed by any additive manufacturing method. Purely exemplary, additive construction can be performed by laser beam melting, laser beam sintering, laser powder welding, arc additive manufacturing, or any other additive manufacturing method. In other words, the present invention proposes a combination of two manufacturing methods, which can be particularly referred to as "hybrid manufacturing," and for example, combining the manufacture of the substrate by conventional manufacturing methods (i.e., particularly subtractive methods) with the manufacture of the armor layer by additive manufacturing methods. The casting mold matrix, which is composed of or has a matrix material, particularly provides the main part of the casting mold, for example, in terms of the volume or mass of the casting mold. As the armor layer, one or several (particularly a defined number) layers with typical layer thicknesses of additive manufacturing methods can be constructed. The exact layer thickness and the total thickness depend here on the casting process to be performed, or can be selected or adjusted accordingly.

[0009] As described above, the at least one armor layer can be additively constructed on any section of the casting mold matrix, thereby defining the cavity in that area. In other words, in the constructed state, the armor layer can be disposed between the cavity and the matrix material disposed beneath the armor layer to protect the matrix material from contact with the aluminum poured into the cavity.

[0010] In this method, it can be specifically specified that the at least one armor layer is constructed on at least one locally defined section of the substrate. For example, multiple armor layers can be selectively constructed planarly on the substrate material on each locally defined section of the substrate (e.g., at different locations on the substrate). Thus, particularly in areas of the casting mold subjected to high wear, armor layers can be selectively applied to protect the substrate material there. Accordingly, armor layers can be applied only at local locations necessary or advantageous for extending service life. In general, relatively inexpensive and easily manufactured substrate materials can thus be used in all areas of the casting mold not subjected to high wear, while armor layers are used where needed, to obtain a casting mold with low overall manufacturing cost and the longest possible service life. Within the scope of this method, a single armor layer or a defined number of armor layers can be constructed to achieve a “coating” of the substrate beneath it. Similarly, a large number of armor layers can be constructed to form a volumetric region consisting of armor layers, which can be thicker, stronger, or higher than the substrate beneath it.

[0011] According to one embodiment of the method, the at least one locally confined segment on which the at least one armor layer is additively constructed can be determined based on simulation and / or based on process-induced removal of the casting mold, particularly based on the determined wear and / or abrasion and / or forces acting in the process and / or turbulence occurring in the casting material during the process and / or based on the function or geometry of the segment. In other words, those locally confined segments in the casting mold that are expected to experience high wear during the process or that have experienced or have already experienced high wear can be reinforced by the at least one armor layer.

[0012] Wear can be determined, for example, by simulating the casting process, in which at least one section can be identified that exhibits more severe abrasion (i.e., mechanical and / or chemical removal of the casting material) compared to at least one other section of the casting mold. Similarly, the at least one section can be determined from the casting process itself, for example, by identifying which sections exhibit what degree of wear after a certain number of casting processes.

[0013] For example, the at least one localized limiting section can also be determined based on the forces acting in the process, transmitted from the casting material to the mold, or based on the turbulence occurring in the casting material during the process. The greater the forces acting between the casting material and the mold, such as at locations where the melt is redirected or where flow conditions are altered by changes in cross-section within the cavity, or the stronger the turbulence in the casting material, the more severe the removal or wear will occur at the corresponding section of the mold. Similarly, the at least one localized section to be coated with the armor layer can also be determined based on its function or its geometry. It has been shown here that, for example, more severe wear may occur depending on the curvature and fill flow of the mold section. Likewise, sections performing different functions in the casting process, such as inlet sections, redirection sections, and sections with changes in cross-section, can be reinforced or protected by the armor layer because these sections typically exhibit high wear.

[0014] This method can be further improved so that the armor material exhibits chemical resistance to the casting material, particularly higher chemical resistance compared to the base material. As described, aluminum is used as the casting material; therefore, according to the described embodiment, the armor material exhibits higher chemical resistance to molten aluminum compared to the base material. This ensures that, in the section coated with the armor material (i.e., on the armored section), the wear effect caused by chemical reaction is reduced relative to other unprotected areas of the base material. In other words, especially compared to the base material, the armor layer exhibits little or no chemical reaction upon contact with the casting material.

[0015] Furthermore, this method can specify that the base material is softer than the armor material, particularly in the range <60 HRC, while the armor material is particularly in the range >60 HRC, and / or the armor material has defined thermal expansion and thermal conductivity. Because the armor material is constructed to be harder than the base material, mechanical wear on the armor material or armor layer is reduced relative to the originally unprotected base surface. Moreover, the defined thermal expansion and thermal conductivity of the armor material allow the casting process to be performed while adhering to predetermined boundary conditions. In particular, the armor layer has sufficient thermal conductivity to ensure heat transfer between the remaining parts of the casting mold and the casting material during the casting process.

[0016] Furthermore, this method may specify that the base material is composed of, in particular, low-alloy or high-alloy steel, and / or the armor layer is composed of or includes hard metals, heavy metals, or refractory metals (especially tungsten). As mentioned at the beginning, the base of the casting mold can be obtained by conventional manufacturing processes, such as milling. Steel, especially low-alloy or high-alloy steel, can be used as the base material. In principle, hard metals, heavy metals, or refractory metals, such as tungsten, can be used to form the armor layer, i.e., as the armor material. Alternatively, compounds (e.g., titanium nitride) or alloys or mixtures can also be used as the armor material, including hard metals, heavy metals, or refractory metals such as tungsten carbide-cobalt, tungsten alloys, or pure tungsten.

[0017] As mentioned at the beginning, in principle, a substrate for a casting mold is provided, on which an armor layer is additively constructed at least one section. In another embodiment of the method, it may be specified, particularly by means of a detection device, to detect one or more state parameters of the casting mold, particularly the at least one section and / or the at least one armor layer, and to construct the at least one armor layer based on the one or more state parameters. The one or more state parameters may, for example, generally describe the state of the casting mold section and / or the armor layer, particularly the extent to which it is intact or conforms to the target geometry and material properties.

[0018] For example, it can be determined whether the section of the casting mold to be coated with the armor layer meets the target state based on one or more state parameters. Similarly, it can be determined whether the casting mold has wear requiring repair. For example, the wear state of a previously coated armor layer can be determined, and accordingly, the extent to which the armor layer must be reconstructed can be determined. In other words, in principle, a manufacturing method can be implemented in which an armor layer is constructed on the substrate of the casting mold. Likewise, a modification, particularly repair or maintenance, can be performed in which either a portion of the substrate is replaced with an armor layer and an armor layer is constructed thereon, or a previously constructed armor layer is repaired. In particular, an armor layer can also be added to a casting mold that previously did not include an armor layer. For example, the one or more state parameters can be detected 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 what topology the armor layer must have, or how the armor layer should be coated, to achieve the target dimension.

[0019] Based on the state parameters described above, at least a portion of a previously constructed armor layer and / or at least a portion of the casting mold can be removed. For example, if the casting mold shows wear in an area of ​​previously coated armor layer, the armor layer can be partially removed, thereby enabling the defined armor layer reconstruction on the previously coated armor layer or on the exposed portion of the armor layer. Similarly, any other casting mold can be provided, where a portion of the casting mold, i.e., a portion of the substrate, can be removed, thereby enabling the subsequent coating of a defined armor layer thereon, for example by replacing an area of ​​the casting mold previously formed there. In other words, an armor layer can also be added where the casting mold did not previously include an armor layer. The defined removal of at least a portion of the armor layer or the casting mold can, in principle, be carried out in any manner, particularly mechanically, such as by milling, grinding, or by electrical discharge machining, ablation, or other removal methods. In particular, by removing at least a portion of the casting mold or the armor layer, the casting mold can be prepared, enabling the defined (re)construction of the armor layer.

[0020] In addition to this method, the present invention also relates to a casting mold for an aluminum casting process, which is manufactured in particular according to the above-described method. The casting mold is designed to at least partially limit a cavity for receiving liquid aluminum during the aluminum casting process, wherein the casting mold has a matrix made of a base material and at least one armor layer that limits the cavity in at least one section of the matrix. The armor layer is constructed by an additive manufacturing method from an armor material different from the base material.

[0021] Furthermore, the present invention relates to a method for manufacturing cast components using a casting mold, comprising the following steps:

[0022] - Provide casting molds as described above, especially casting molds manufactured by the methods described above;

[0023] - Aluminum is poured into a cavity bounded by a casting mold.

[0024] In other words, the above method can be used to manufacture or modify casting molds, which can then be used in casting processes, particularly aluminum casting processes. Advantageously, the armor layer manufactured here protects the underlying substrate material from contact with the casting material (especially aluminum), thereby enabling a longer service life for the casting mold.

[0025] All advantages, details, implementation methods and / or features described in the method for manufacturing casting molds can be fully transferred to the casting molds and the method for manufacturing casting components. Attached Figure Description

[0026] This invention is illustrated with reference to embodiments and the accompanying drawings. The drawings are schematic representations and illustrations:

[0027] Figure 1 This is a schematic diagram illustrating the principle of a method for manufacturing a casting mold for an aluminum casting process according to one embodiment.

[0028] Figure 2 A schematic diagram of a flowchart illustrating a method for manufacturing a casting mold for an aluminum casting process according to one embodiment; and

[0029] Figure 3 This is a partial schematic diagram of a casting mold used in the aluminum casting process. Detailed Implementation

[0030] Figure 1 The illustration schematically depicts a scenario during a method for manufacturing a casting mold 1 for an aluminum casting process. The casting mold 1 has a base 2 made of a base material, such as steel, particularly low-alloy steel or high-alloy steel. The exemplary base 2 may represent a half-mold of the casting mold 1, which may be, for example, as... Figure 3 The cavity 3 is defined by supplementing it with another half-mold. When performing a process that can use the casting mold 1, casting material or melt, particularly liquid or molten aluminum, is introduced into the cavity 3.

[0031] Here, the casting mold 1 has a first section 4 on which the base 2 defines the cavity 3. Furthermore, two second sections 5 are shown purely illustratively. The configurations of the individual sections 4 and 5 can be arbitrarily chosen or implemented, and are used below for illustrative purposes only. Figure 1 In the schematically illustrated manufacturing process, a substrate 2 is provided, as described above, which is made of a substrate material. The substrate 2 can be manufactured, for example, by conventional manufacturing methods, particularly milling. Exemplarily, an armor layer 6 is additively constructed in each section 5 of the casting mold 1, the armor layer being composed of or comprising an armor material different from the substrate material. The armor layer 6 may comprise multiple layers or coatings. In other words, the casting mold 1 defines the cavity 3 in section 4 through the substrate 2 and in section 5 through the armor layer 6 disposed therein. The constructed armor layer 6 protects the surface of the substrate 2 beneath it or the substrate material disposed therein in region 5 from contact with the melt (particularly molten aluminum).

[0032] The armor layer 6 is applied locally (i.e., selectively and locally confined) within section 5, which can be performed by any suitable additive manufacturing operation, such as laser beam melting, laser beam sintering, arc additive manufacturing, etc. Purely exemplary, an additive manufacturing apparatus 7 is shown, designed to selectively, layer by layer, coat the armor layer 6 onto the substrate 2, for example, by melting the coated armor material within section 5 using an energy beam or laser beam. The manufacturing apparatus 7 will be adapted accordingly depending on the additive manufacturing process used.

[0033] As described above, the armor material forming the armor layer 6 is made of a material different from the matrix material of the substrate 2 of the casting mold 1. In particular, the armor material has higher chemical resistance to the melt (i.e., molten aluminum) than the substrate material. For example, no chemical reaction occurs between the armor material and the melt, or a significantly smaller chemical reaction occurs. The armor material is particularly harder than the substrate material, thus the substrate material is correspondingly softer than the armor material. The substrate 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 the range of >60 HRC. For example, the armor material is formed of, or includes, hard metals, heavy metals, or refractory metals. The armor material may, for example, contain tungsten, titanium nitride, tungsten carbide-cobalt, or other alloys, mixtures, or compounds that include such hard metals, heavy metals, or refractory metals.

[0034] To ensure the reliable execution of the aluminum casting process, the armor material must possess defined thermal expansion and thermal conductivity. The thermal conductivity of the armor material in armor layer 6 must be particularly sufficient to allow heat dissipation from the molten metal through the substrate 2. The thermal expansion characteristics should ensure adequate durability as well as tooling and process stability.

[0035] For example, Figure 1 The method illustrated in one process step can be based on Figure 2 The process is performed using a flowchart schematically shown in the diagram. The method can begin at block 8, where a base 2 is provided. As described above, the base 2 can be made of or comprise steel and is provided by conventional manufacturing processes, such as milling.

[0036] Optionally, state parameters of the substrate 2 can be detected, for example, optically, in block 9. State parameters describe, for example, the state of the substrate 2, particularly its topology or geometric information. The substrate 2 can be, for example, a new tool part or casting mold part, a tool part or casting mold part to be repaired or maintained, or a tool part or casting mold part to be installed. For simplicity, the tool part or casting mold part will be referred to as a "tool part" below. A part manufactured using the casting mold 1 can be referred to as a "component". "Tool part" or "tool assembly" can therefore refer to a component of the tool (i.e., the casting mold 1), such as a contour insert of the tool or casting mold 1. A "component" can refer to a product produced using the casting mold 1 in a casting process, such as a body part for a motor vehicle. If the substrate 2 provided in block 8 is a new tool part, detecting state parameters in block 9 may not be necessary, as the geometric details of the substrate 2 are known in this case. If you want to add armor layer 6 to base 2 or repair the armor layer, you can determine its status by detecting the status parameters in block 9, such as the degree of wear progress of armor layer 6 or base 2.

[0037] Further optionally, the amount to be removed can be determined in block 10 based on previously determined state parameters, or removal can be performed. In other words, at least a portion of the previously applied armor layer 6 and / or at least a portion of the base 2 can be definitively removed so that the armor layer 6 can be subsequently constructed or reconstructed in a better manner. If the base 2 is a new tooling part, the described removal is not necessary and should therefore be understood as optional. The final geometry of the base 2 and the armor layer 6 here corresponds to the original target geometry of the casting mold 1, i.e., the base 2 is reduced accordingly so that the armor layer 6 coated thereon reaches the target size. The armor layer 6 can be understood as being coated on the base 2 (see...). Figure 1 (left side area) or also "buried" (see Figure 1 The right-side region is embedded in the base 2 so as not to alter the tool profile, or the final geometry formed by the casting mold 1 through the armor layer 6. Typically, an "offset" can be introduced into the base 2 to achieve the desired target geometry through the thickness of the coated armor layer 6.

[0038] In any case, it can then be determined in block 11 which sections 5 should have armor layers 6 built, repaired, or added. Next, in block 12, armor layers 6 can be built in sections 5 through additive manufacturing operations, thereby creating casting mold 1, repairing it, or adding it through armor layers 6.

[0039] A purely exemplary casting mold 1 is shown in sectional view. Figure 3In the casting mold 1, there are correspondingly two half-molds, each half-mold having a base 2 and an armor layer 6 exemplarily coated thereon. The forming of the casting mold 1 and the arrangement of the various armor layers 6 are arbitrary and are for illustrative purposes only. As schematically shown by arrow 13, in the aluminum casting process, molten metal is introduced into the cavity 3.

[0040] The determination of which sections 5 and 14-16 should have armor layers 6 (as described above with reference to block 11) can be made, for example, by referring to the first armor layer 6, based on the function of section 14. Section 14 can be an inlet section through which the molten material flows into the cavity 3. High turbulence is typically expected in this region of the casting material or molten material, so it is meaningful to construct an armor layer 6 there to protect the underlying matrix material.

[0041] A turning section and / or cross-sectional variation within the cavity 3 or casting mold 1 is formed on another section 15, causing the melt to exert relatively high forces and turbulence on the casting mold 1. Therefore, an armor layer 6 is also determined to be provided on section 15. Furthermore, section 16 shows a region of the cavity 3 where high turbulence is expected, and therefore a corresponding armor layer 6 is also constructed there. Figure 3 As can be seen from the exemplary casting mold 1, for example by simulating or based on wear images of the casting mold 1 used in the casting process, it is possible to determine which areas of the casting mold 1 show higher wear, so that these areas can be reinforced by the corresponding armor layer 6.

[0042] The advantages, details and features shown in the various embodiments can be combined, interchanged and used in any way.

[0043] List of reference numerals in the attached diagram:

[0044] 1. Casting mold

[0045] 2. Matrix

[0046] Type 3 cavity

[0047] Sections 4 and 5

[0048] 6 Armor Layers

[0049] 7 Manufacturing equipment

[0050] 8-12 squares

[0051] 13 arrows

[0052] Sections 14-16.

Claims

1. A method for manufacturing a casting mold (1) for an aluminum casting process, the casting mold (1) at least partially defining a cavity (3) designed to receive liquid aluminum during the aluminum casting process, characterized in that, A substrate (2) made of a base material is provided for casting mold (1), and at least one armor layer (6) that limits the cavity (3) is constructed by additive manufacturing method on at least one section (5, 14-16) of the substrate (2) from an armor material different from the base material.

2. The method according to claim 1, characterized in that, The at least one armor layer (6) is constructed on at least one locally bounded segment (5, 14-16) of the substrate (2).

3. The method according to claim 2, characterized in that, The at least one locally bounded section (5, 14-16) is determined based on simulation and / or based on process-induced removal of the casting mold (1), particularly based on wear and / or abrasion and / or forces acting in the process and / or turbulence occurring in the casting material in the process and / or based on the function of the section (5, 14-16) and / or the geometry of the section (5, 14-16).

4. The method according to any one of the preceding claims, characterized in that, The armor material exhibits chemical resistance to casting materials, particularly higher chemical resistance compared to the matrix material.

5. The method according to any one of the preceding claims, characterized in that, The base material is softer than the armor material, particularly in the range of <60 HRC, while the armor material is particularly in the range of >60 HRC, and / or the armor material has defined thermal expansion and thermal conductivity.

6. The method according to any one of the preceding claims, characterized in that, The base material is made of, in particular, low-alloy or high-alloy steel, and / or the armor layer (6) is made of or includes hard metals or heavy metals or refractory metals, in particular tungsten.

7. The method according to any 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), especially the at least one section (5, 14-16) and / or the at least one armor layer (6), is detected, and the at least one armor layer (6) is constructed according to 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 portion of the previously constructed armor layer (6) and / or at least a portion of the casting mold (1) is removed.

9. A casting mold (1) for an aluminum casting process, particularly a casting mold (1) for an aluminum casting process manufactured according to the method of any one of the preceding claims, the casting mold (1) being designed to at least partially define a cavity for receiving liquid aluminum during the aluminum casting process, characterized in that, The casting mold (1) has a matrix (2) made of a matrix material and an armor layer (6) that defines a cavity (3) in at least one section (5, 14-16) of the matrix (2), the armor layer being constructed by an additive manufacturing method from an armor material different from the matrix material.

10. A method for manufacturing a cast component by means of a casting mold (1), the method comprising the steps of: - Provide a casting mold (1) according to the preceding claims; - The aluminum is poured into the cavity (3) bounded by the casting mold (1).

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