Molded body for a casting mold and method for producing the molded body

Abstract

Mold body (1) for a casting mold (2), comprising a shell body (3) produced from a metal by means of a 3D printing process, wherein the shell body (3) has cavities (4) which are filled with a metal, characterized in that: - the shell body (3) is made of steel and the cavities (4) are each formed as a hollow cylinder, - the cavities (4) are filled with a zinc-aluminum alloy (5), - the shell body (3) has a base section (8) and a shell body section (7) printed thereon by means of a 3D printing process, wherein the respective cavity (4) extends through the base section (8) into the printed shell body section (7), and - the base section (8) and the shell body section (7) printed by means of a 3D printing process are made of the same steel alloy or the base section is made of a hot-work steel and the shell body section is made of a tool steel.

Description

The invention relates to a shaped body for a casting mold according to the features of the preamble of claim 1 and to a method for producing the shaped body.As described in DE 199 03 436 A1, a method for producing three-dimensional shaped bodies from fusible material is known from the prior art. A cladding body is built up in layers by means of laser beam precision build-up welding or selective laser sintering. A cavity formed in the enveloping body is then filled with the enveloping body material or a second material.US 2022 / 0016711 A1 describes metal objects and structures which are additively manufactured from metal and have a filling pattern infiltrated with a second metal. In addition, methods for forming such objects and structures are provided herein.DE 10 2016 211 051 A1 discloses a shaping tool and a method for producing a shaping tool. The forming tool has a base plate, a frame structure and a tool wall with a forming surface. The bottom plate, the frame structure and the tool wall define a cavity filled with a loose filling material.US 2016 / 0039006 A1 describes a method for producing a component. A shell is formed by an additive manufacturing process to have an inner surface defining a cavity. The cavity is filled with a liquid material, during which a heat transfer liquid is applied to the shell. The liquid material is solidified.The object of the invention is to specify a shaped body for a casting mold which is improved compared to the prior art and a method for producing a shaped body for a casting mold which is improved compared to the prior art.The object is achieved according to the invention by a shaped body for a casting mold having the features of claim 1 and a method for producing a shaped body for a casting mold having the features of claim 2.Advantageous embodiments of the invention are the subject matter of the dependent claims.An, in particular three-dimensional, shaped body for a casting mold has an enveloping body produced at least in sections from a metal by means of a 3D printing method, wherein the enveloping body has cavities which are filled with a metal.According to the invention, the enveloping body is formed from steel and the cavities are each formed as a hollow cylinder. According to the invention, the cavities are filled with a zinc-aluminum alloy.In a method according to the invention for producing the molded body, the enveloping body is printed at least in sections from steel by means of the 3D printing method and is formed in such a way that it has the cavities, which are each formed as a hollow cylinder, are open at a base-side end and are closed at an opposite end, wherein these cavities are subsequently filled with the zinc-aluminum alloy.According to the invention, the enveloping body has a base section and an enveloping body section printed thereon by means of the 3D printing method, wherein the respective cavity extends through the base section into the printed enveloping body section.According to the invention, the enveloping body is formed by printing the enveloping body section by means of the 3D printing method on the base section, wherein the base section has a cavity section formed as a through opening with the opened base-side end of the respective cavity and the enveloping body section is printed by means of the 3D printing method on the base section in such a way that a respective cavity section of the respective cavity in the enveloping body section printed by means of the 3D printing method adjoins a respective cavity section formed in the base section. As a result, the respective cavity extends through the base section into the enveloping body section printed by means of the 3D printing method.For example, it is also possible to simultaneously form a plurality of enveloping bodies in the described manner by printing the respective enveloping body section by means of the 3D printing method on a respective base section, for example if there is sufficient area on a construction panel of a 3D printing device carrying out the 3D printing method for arranging a plurality of base sections.The base section and the enveloping body section printed by means of the 3D printing method are or are formed in the method according to the invention from the same steel alloy or the base section from a hot-work steel and the enveloping body section from a tool steel.The base portion is formed of, for example, a hot-work steel X38CrMoV5. The steel, in particular hot-work steel, for the base section has, for example, the following components:carbon, in particular 0.35%silicon, in particular 0.2%,manganese, in particular 0.5%,chromium, in particular 5%,molybdenum, in particular 2.3%, andvanadium, in particular 0.6%.The 3D printing method is also referred to as 3D printing or additive manufacturing method. As a 3D printing method, in particular a 3D laser printing method is used, also referred to as laser printing, in particular selective laser melting, also referred to as SLM or SLM metal printing. Alternatively, other 3D printing methods, in particular also other 3D laser printing methods, can also be used, in particular 3D printing methods for processing steel alloys, in particular in powder form.In one embodiment, the cavities are filled with the zinc-aluminum alloy by gravity casting or are filled with the zinc-aluminum alloy by gravity casting in the method.According to the invention, the base section is formed or is formed in the method in such a way that it has, on a base side, a circumferential wall surrounding a region with all passage openings on the circumference and / or a channel structure connecting, in particular milled, all passage openings to one another. The circumferential wall and / or the channel structure form in particular a casting system and a melt distributor for the zinc-aluminum alloy. This casting system does not have to be removed or remachined, as a result of which costs in this respect are saved. Possible casting porosity at the bottom side of the base section is not relevant and thus does not require reworking.The zinc-aluminum alloy is cast in, for example, via a trough or by means of a casting spoon. A metering quantity corresponds, for example, to the cavities to be filled or is smaller in order to avoid overflow and subsequent reworking.In one embodiment of the method, after the at least partial printing of the enveloping body by means of the 3D printing method, in particular after the printing of the enveloping body portion by means of the 3D printing method on the base portion, a metal powder, in particular steel powder, which has remained in the cavities is removed, in particular suctioned off, in particular via the through openings in the base portion, before the filling of the cavities with the zinc-aluminum alloy is carried out.It is provided in particular that the base section is also formed in the method in the described manner. It is provided in particular that the base section is formed from steel, for example from the hot-work steel X38CrMoV5or another steel, that the through-openings are introduced into the base section, in particular are drilled, and that advantageously, on the bottom side of the base section, the circumferential wall surrounding the region with all through-openings on the circumferential side and / or the channel structure connecting all through-openings to one another is formed. The channel structure is milled in particular into the base side.Further process steps can, if required, be carried out, for example before or after filling of the cavities, for example a heat treatment, a sizing and / or a general processing of a surface of the enveloping body and / or of the shaped body. After the heat treatment, the enveloping body and / or shaped body has, for example, a hardness of 45 HRC.The casting mold for which the molded body is provided is, for example, a die casting mold or a casting mold for another casting method. The shaped body is in particular an insert, in particular a contour insert, for this casting mold. It forms in particular a component of this casting mold.In the described solution, the molded body is in particular not a solid solid material body, but rather has the described cavities which are formed as cylindrical, in particular hollow cylindrical, or rod-shaped recesses and are each open toward the bottom, i.e. each have the open bottom end. This is achieved in particular by the described at least sectionwise printing of the enveloping body. These cavities are then filled with the zinc-aluminum alloy.Since in the described solution less steel material therefore has to be printed by means of the 3D printing method than in the case of a solid solid solid material molded body printed by means of a 3D printing method, the described solution is more cost-effective and faster. The solution described thus makes it possible to produce cost-effective complex shaped bodies, in particular contour inserts, for casting moulds.The cavities form, for example, a honeycomb structure.As a result of the described solution, the molded body has in particular a very good thermal conductivity, rigidity and strength and a reduced residual workpiece stress, as a result of which a risk of crack formation which would lead to rejects is reduced. The shaped body is designed in particular according to requirements in die casting. Depending on the contour of the molded body, a number and size of the cavities can be optimized with regard to minimizing the material to be printed, in order to optimize the speed during production and the material saving and thus the costs.The cavities would be disadvantageous for the thermal conductivity, in particular in a casting process by means of the casting mold with the molded body, since the cavities are filled with air which blocks a transport of heat. This disadvantage is avoided by filling the cavities with the zinc-aluminum alloy, because the zinc-aluminum alloy advantageously has a very high thermal conductivity and is advantageously very cost-effective.The zinc-aluminum alloy can be used as a filling for the cavities, since during the casting process, in particular during die casting, it does not come directly into contact with a melt used for this die casting by means of the casting mold comprising the shaped body, but is shielded from this melt by the enveloping body made of more temperature-resistant steel, so that the thermal load for the filling material, i.e. for the zinc-aluminum alloy, is lower in the cavities. Only the steel enveloping body comes into direct contact with the melt during die casting.The zinc-aluminum alloy is, for example, ZnAl4, also referred to as Zamak 3, in particular having ASTM number AG40A and / or UNS number Z335020. The zinc-aluminum alloy has, for example, the following components:aluminum, in particular 3.7% to 4.3%magnesium, in particular 0.02% to 0.06%,copper, in particular a maximum of 0.1%,iron, in particular 0.05%,lead, in particular at most 0.005 %,cadmium, in particular at most 0.004%,tin, in particular at most 0.002%, andzinc, the proportion of which in particular forms the remaining residual proportion of 100%.As steel for the 3D printing method, i.e. in particular for forming the enveloping body section printed by means of the 3D printing method, use is made, for example, of the tool steel 1.2709, also referred to as X3NiCoMoTi18-9-5. The steel for the 3D printing process has in particular the following components:nickel, in particular 17% to 19%,cobalt, in particular 8.5% to 10%,molybdenum, in particular 4.5% to 5.2%,titanium, in particular 0.8% to 1.2%,carbon, in particular ≤0.03%,silicon, in particular ≤0.1%,manganese, in particular ≤0.15%,phosphorus, in particular ≤0.01%,sulfur, in particular ≤0.01%,chromium, in particular ≤0.25%, andiron whose proportion in particular forms the remaining residual proportion of 100%.Exemplary embodiments of the invention are explained in more detail below with reference to drawings.The following are shown: FIG. 1 schematically shows a base section of an enveloping body of a molded body to be produced on a construction panel of a 3D printing device, FIG. 2 schematically shows an enveloping body of the molded body to be produced, having the base section and an enveloping body section printed on the base section, FIG. 3 schematically shows a top view of the enveloping body of the molded body to be produced, FIG. 4 schematically shows a sectional illustration of the enveloping body from FIG. 3, FIG. 5 schematically shows a further sectional illustration of the enveloping body from FIG. 3, FIG. 6 schematically shows a further sectional illustration of the enveloping body from FIG. 3, FIG. 7 schematically shows a further sectional illustration of the enveloping body from FIG. 3, FIG. 8 schematically shows a transparent representation of the enveloping body from FIG. 3, FIG. 9 schematically shows a plan view from below of the enveloping body from FIG. 3, wherein only the base section is shown here, FIG. 10 is a schematic bottom plan view of the molded body finished by pouring a zinc-aluminum alloy into the enveloping body, only a base section of the finished molded body being shown here, FIG. 11 schematically shows a casting mold into which the molded body can be inserted, FIG. 12 schematically shows the casting mold from FIG. 11 with the molded body inserted, FIG. 13 schematically shows a thermal conductivity of air in at least one cavity of the enveloping body as a function of temperature, and FIG. 14 schematically shows a thermal conductivity of the zinc-aluminum alloy filled into the enveloping body for finishing the molded body as a function of the temperature.Corresponding parts are provided with the same reference numerals in all figures.With reference to FIGS. 1 to 10, a shaped body 1 for a casting mold 2 and its production are described below.The casting mold 2 for which the molded body 1 is provided is illustrated by way of example in FIGS. 11 and 12, wherein FIG. 11 shows the casting mold 2 without the molded body 1 and FIG. 12 shows the casting mold 2 with the molded body 1 inserted. The casting mold 2 is a die casting mold in the example shown. The shaped body 1 is in particular an insert, in particular a contour insert, for the casting mold 2.A molded body 1 has an enveloping body 3 produced at least in sections by means of a 3D printing method, in particular by means of selective laser melting. The enveloping body 3 is formed from steel and has cavities 4 which are each formed as a hollow cylinder and are filled with a zinc-aluminum alloy 5, in particular by gravity casting.To produce this molded body 1, the enveloping body 3 is printed at least in sections from steel by means of the 3D printing method, in particular by means of selective laser melting, and is formed in such a way that it has the cavities 4, which are each formed as a hollow cylinder, are open at a base-side end 6 and are closed at an opposite end. Subsequently, these cavities 4 are filled with the zinc-aluminum alloy 5, in particular by gravity casting.In the illustrated embodiment of the method, the enveloping body 3 is formed by printing an enveloping body section 7 by means of the 3D printing method, in particular by means of selective laser melting, on a base section 8. In the example shown, for this purpose the prefabricated base section 8 is arranged on a construction plate P of a 3D printing device, as shown in FIG. 1, and is for example screwed and pinned.The base section 8 has through-openings 9 as a constituent part of the cavities 4. The respective through-opening 9 forms a cavity section with the opened bottom end 6 of the respective cavity 4. Since the number of through-openings 9 corresponds to the number of cavities 4, more than two through-openings 9 are advantageously present, as shown for example in FIG. 9.The envelope portion 7 is printed on the base portion 8 by the 3D printing method as shown in FIG. 2. In this case, the enveloping body section 7 is printed onto the base section 8 by means of the 3D printing method in such a way that a respective cavity section of the respective cavity 4 in the enveloping body section 7 printed by means of the 3D printing method adjoins a respective cavity section formed in the base section 8. As a result, the respective cavity 4 extends through the base section 8 into the enveloping body section 7 printed by means of the 3D printing method, as shown in FIGS. 4 to 7, which show different sectional representations of the enveloping body section 3 from FIG. 3, and as likewise shown in FIG. 8 in a transparent representation of the enveloping body 7.The enveloping body 3 thus has the base section 8 and the enveloping body section 7 printed thereon by means of the 3D printing method, in particular by means of selective laser melting, wherein the respective cavity 4 extends through the base section 8 into the printed enveloping body section 7.A metal powder remaining in the cavities 4 after this production of the enveloping body 3, in particular steel powder, which has not been processed, i.e. in particular has not been melted, during the 3D printing process, is removed, in particular suctioned off, in particular via the through-openings 9 in the base section 8, before the filling of the cavities 4 with the zinc-aluminum alloy 5 is carried out in the manner described above, i.e. by pouring the zinc-aluminum alloy 5 into the cavities 4 in order to fill them.As shown in FIG. 9, the base section 8 is designed in such a way that it has, on a base side, a circumferential wall 10 surrounding a region with all passage openings 9 on the circumference and / or a channel structure, in particular milled, connecting all passage openings 9 to one another. The channel structure is not shown here.The circumferential wall 10 and / or the channel structure form in particular a casting system and a melt distributor for the zinc-aluminum alloy 5, as shown in FIG. 10.This casting system does not have to be removed or remachined, as a result of which costs in this respect are saved. A possible casting porosity at the bottom side of the base section 8 is not relevant and thus does not require any reworking.The zinc-aluminum alloy 5 is cast in, for example, via a trough or by means of a casting spoon. A metering quantity corresponds, for example, to the cavities 4 to be filled or is smaller in order to avoid overflow and subsequent reworking.Further method steps can, if required, be carried out, for example before or after filling of the cavities 4, for example a heat treatment, a sizing and / or a general processing of a surface of the enveloping body 3 and / or of the shaped body 1.After completion of the molded body 1, the molded body 1 is inserted into the casting mold 2, in particular die casting mold, as shown in FIGS. 11 and 12. FIG. 11 shows the casting mold 2 before the insertion of the molded body 1 and FIG. 12 shows the casting mold 2 with the inserted molded body 1.As a result of the described solution, the molded body 1 has in particular a very good thermal conductivity λ, rigidity and strength and a reduced residual workpiece stress, as a result of which a risk of crack formation which would lead to rejects is reduced. The molded body 1 is designed in particular according to requirements in die casting. Depending on the contour of the molded body 1, a number and size of the cavities 4 can be optimized with regard to minimizing the material to be printed, in order to optimize the speed during production and the material saving and thus the costs.The cavities 4 would be disadvantageous for the thermal conductivity λ, in particular in a casting process by means of the casting mold 2 with the molded body 1, since the cavities 4 are filled with air which blocks a transport of heat. This disadvantage is avoided by filling the cavities 4 with the zinc-aluminum alloy 5, because the zinc-aluminum alloy 5 advantageously has a very high thermal conductivity λ and is advantageously very cost-effective. This is clear with reference to FIGS. 13 and 14, which each show a diagram of the thermal conductivity λ as a function of the temperature T. FIG. 13 shows a thermal conductivity AL of air in at least one cavity 4 of the enveloping body 3 as a function of the temperature T. FIG. 14 shows, in comparison thereto, a thermal conductivity λZALof the zinc-aluminum alloy 5 in the at least one cavity 4 of the enveloping body 3 filled with this zinc-aluminum alloy 5, i.e. in the finished molded body 1, as a function of the temperature T.

Claims

Shaped body (1) for a casting mould (2), having an enveloping body (3) produced from a metal by means of a 3D printing method, wherein the enveloping body (3) has cavities (4) which are filled with a metal, characterized in that - the enveloping body (3) is formed from steel and the cavities (4) are each formed as a hollow cylinder, - the cavities (4) are filled with a zinc-aluminium alloy (5), - the enveloping body (3) has a base section (8) and an enveloping body section (7) printed thereon by means of the 3D printing method, wherein the respective cavity (4) extends through the base section (8) into the printed enveloping body section (7), and the base section (8) and the enveloping body section (7) printed by means of the 3D printing method are formed from the same steel alloy or the base section is formed from a hot-work steel and the enveloping body section from a tool steel.Method for producing a shaped body (1) according to Claim 1, wherein the enveloping body (3) is printed at least in sections from steel by means of a 3D printing method and is formed in such a way that it has the cavities (4) which are each formed as a hollow cylinder, are open at a base-side end (6) and are closed at an opposite end, wherein these cavities (4) are subsequently filled with the zinc-aluminium alloy (5), wherein the enveloping body (3) is formed by printing the enveloping body portion (7) by means of the 3D printing method on the base portion (8), wherein the base portion (8) has a cavity portion formed as a through-opening (9) with the open base-side end (6) of the respective cavity (4) and the enveloping body portion (7) is printed in this way on the base portion (8) by means of the 3D printing method, a respective cavity portion of the respective cavity (4) in the enveloping body portion (7) printed by means of the 3D printing method adjoins a respective cavity portion formed in the base portion (8), as a result of which the respective cavity (4) extends through the base portion (8) into the enveloping body portion (7) printed by means of the 3D printing method, wherein the base portion (8) and the enveloping body portion (7) printed by means of the 3D printing method are formed from the same steel alloy or the base portion is formed from a hot-work steel and the enveloping body portion is formed from a tool steel, and wherein the base portion (8) is formed in such a way that it has a circumferential wall (10) peripherally enclosing a region having all through-openings (9) and / or a channel structure interconnecting all through-openings (9).Method according to Claim 2, characterized in that a 3D laser printing method, in particular selective laser melting, is used as the 3D printing method.Method according to Claim 2 or 3, characterized in that the cavities (4) are filled with the zinc-aluminium alloy (5) by gravity casting.Method according to one of Claims 2 to 4, characterized in that a metal powder remaining in the cavities (4) after the at least partial printing of the enveloping body (3) by means of the 3D printing method is removed before the cavities (4) are filled with the zinc-aluminium alloy (5).

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