Method for manufacturing injection-molded components

Abstract

The present invention relates to a method for producing injection-molded components using an injection mold with at least a first and a second mold cavity, comprising the following steps: - a) Heating at least one metal part to a metal part temperature, of which a first and / or a second surface is arranged to be in contact at least partially with a surface of at least the first mold cavity part and / or with a surface of the second mold cavity part, - b) Injecting at least one plastic into the injection mold, which is arranged to be in contact with the at least one metal part, wherein the metal part temperature is essentially the same as or higher than the temperature of the at least one plastic during the injection of the at least one plastic in step b).

Description

[0001] The present invention relates to a method for producing injection-molded components using an injection mold with at least a first and a second mold cavity, an injection-molded component obtainable by the method, a use of the injection-molded component and a device for producing injection-molded components.

[0002] Injection molding processes are well-known in the art. Manufacturing processes for components comprising a metal part and a plastic part are also known. For some applications, metal parts must be integrated into plastic parts in a high-strength and reliably leak-proof manner against media such as gases or liquids. In known processes, metal and plastic parts are manufactured independently of each other. In the also known process of overmolding metal parts placed in an injection mold, sufficient adhesion with the injected plastic is often not achieved. The molten, injected plastic comes into contact with the metal parts at a lower temperature. The plastic cools at the melt front upon contact with the inserted metal parts. A cooled surface film forms on the plastic, so that the metal surface is not adequately molded.Therefore, there is a need to prevent the formation of a surface film in order to obtain a sufficiently strong, secure bond between the metal part and the plastic.

[0003] The object of the present invention is to provide a method for producing an injection-molded component in which the adhesion between a metal part and an injected plastic is improved.

[0004] This problem is solved according to the invention by a method for producing injection-molded components, in particular injection-molded components in metal-plastic composite, using an injection mold with at least a first and a second mold cavity, comprising the steps: - a) Heating at least one metal part to a metal part temperature, of which a first and / or a second surface is arranged to be in contact at least partially with a surface of at least the first mold cavity part and / or with a surface of the second mold cavity part, - b) Injecting at least one plastic into the injection mold, which is arranged to be in contact with the at least one metal part, wherein the metal part temperature is essentially the same as or higher than the temperature of the at least one plastic during the injection of the at least one plastic in step b).

[0005] When the term "approximately" is used in connection with values ​​or ranges of values ​​within the context of the invention, it refers to a tolerance range that a person skilled in the art considers customary in this field. In particular, a tolerance range of ±20%, preferably ±10%, and more preferably ±5% is provided. Where different ranges are specified for information and / or definitions in the present invention, the lower and upper limits of the different ranges with respect to the respective information, in particular a component, and / or the respective definition, can be combined with one another. Within the context of the present invention, the use of the term "essentially" with respect to a property means a tolerance range that is acceptable to a person skilled in the art from an economic and technical point of view, such that the property is still recognizable as such.

[0006] According to the invention, injection-molded components are produced using an injection mold with at least one first and one second mold cavity. According to the invention, the first mold cavity is heated to a first mold cavity temperature and the second mold cavity to a second mold cavity temperature. Preferably, the first and second mold cavities are identical. Alternatively, the first and second mold cavities are different. For example, the geometry and / or the material can be different. Preferably, the first and / or second mold cavities are made of a material selected from the group comprising ceramics and mixed oxide ceramics, in particular zirconium oxide, magnesium oxide, yttrium oxide, silicon carbide, and / or silicon nitride. Preferably, the first and second mold cavities are made of an identical material.Alternatively, the first and second mold cavity parts are made of different materials. These materials can have different thermal conductivities. Preferably, the first mold cavity part has a first thermal conductivity and the second mold cavity part has a second thermal conductivity. Preferably, the first thermal conductivity of the first mold cavity part and the second thermal conductivity of the second mold cavity part are identical. Alternatively, the first thermal conductivity of the first mold cavity part and the second thermal conductivity of the second mold cavity part are different. Preferably, the first thermal conductivity of the first mold cavity part and / or the second thermal conductivity of the second mold cavity part are in the range of approximately 2 W / m*K and approximately 400 W / m*K, more preferably in the range of approximately 5 W / m*K and approximately 200 W / m*K, and particularly preferably 10 W / m*K and approximately 75 W / m*K according to DIN EN 821-2005, Method A.Preferably, the first thermal conductivity of the first mold cavity part and / or the second thermal conductivity of the second mold cavity part is in the range of approximately 15 W / m*K and approximately 45 W / m*K according to DIN EN 821-2005, Method A, if the material of the first mold cavity part or the second mold cavity part comprises steel. Alternatively, the first thermal conductivity of the first mold cavity part and / or the second thermal conductivity of the second mold cavity part is in the range of approximately 120 W / m*K and approximately 200 W / m*K according to DIN EN 821-2005, Method A, if the material of the first mold cavity part or the second mold cavity part comprises aluminum. Alternatively, the first thermal conductivity of the first mold cavity part and / or the second thermal conductivity of the second mold cavity part is in a range of approximately 200 W / m*K and approximately 400 W / m*K according to DIN EN 821 - 2005, method A, if the material of the first mold cavity part or the second mold cavity part includes copper.Preferably, the first and second mold cavity parts have the same thermal conductivity. Alternatively, the first and second mold cavity parts have different thermal conductivities. In an embodiment with different thermal conductivities of the first and second mold cavity parts, cooling loss can advantageously be reduced.

[0007] Preferably, the first and second mold cavity temperatures are identical. Alternatively, the first and second mold cavity temperatures are different. Preferably, the first and / or second mold cavity temperatures are in a range between approximately 20°C and approximately 250°C, more preferably between approximately 60°C and approximately 220°C, and most preferably between approximately 100°C and approximately 200°C. The first and second mold cavity temperatures depend on the at least one plastic. For example, the first and / or second mold cavity temperatures can be between approximately 20°C and approximately 40°C if the at least one plastic is polypropylene and / or polyethylene.In the process according to the invention, at least one metal part is heated to a metal part temperature, preferably to a temperature above the melting point or melting range of the at least one plastic. Heating the first and second mold cavity parts already provides an initial, but insufficient, heating of the at least one metal part. Preferably, the at least one metal part is heated by induction. The metal part temperature is preferably in a range between approximately 240°C and approximately 420°C, more preferably between approximately 300°C and approximately 410°C, and particularly preferably between approximately 380°C and approximately 400°C, provided that the metal part temperature is essentially equal to or higher than the temperature of the at least one plastic during injection in step b). The metal part temperature should be as high as possible to ensure that the at least one plastic is as fluid as possible.The temperature of the metal part must not be too high, otherwise the at least one plastic component will decompose and burn. Thermal damage would severely reduce the strength and serviceability of the at least one plastic component. The temperature of the metal part is kept as high as possible to ensure wetting with the at least one plastic component, but also below the temperature at which the plastic component would suffer thermal damage. Preferably, the at least one metal part is made of a material selected from the group consisting of aluminum, copper, and steel. Preferably, the at least one metal part is an insert within the at least one plastic component. Preferably, the at least one metal part is a part of the injection-molded component.Preferably, the at least one metal part has a wall thickness in the range of approximately 0.1 mm to approximately 10 mm, more preferably between approximately 0.2 mm and approximately 5 mm, and particularly preferably between approximately 0.5 mm and approximately 0.9 mm. Preferably, the at least one metal part has at least one surface. More preferably, the at least one metal part has a micro- or nanostructure at least on a portion of this surface, which is configured to form undercuts in the surface of the at least one metal part. An etching process and / or laser structuring can be used to produce this micro- and / or nanostructure. Thanks to this micro- and / or nanostructure, a high-strength, gas-tight connection can be created between the at least one plastic part and the at least one metal part.

[0008] In the method according to the invention, a surface of the at least one metal part is arranged in contact, at least partially, with a surface of at least the first mold cavity part and / or with a surface of the second mold cavity part. Preferably, the at least one metal part, in particular a first and / or a second surface of the at least one metal part, is arranged in a recess of the first mold cavity part and / or the second mold cavity part. In the method according to the invention, the at least one metal part preferably has a temperature that is higher than the temperature of the first mold cavity part and the temperature of the second mold cavity part. If the thermal conductivity of the first mold cavity part and / or the thermal conductivity of the second mold cavity part is high, the heat loss of the at least one metal part is also high.If the first thermal conductivity of the first mold cavity and / or the second thermal conductivity of the second mold cavity are low, the heat loss of at least one metal part is low. Thus, depending on the part being produced, an optimal shape can be set by selecting the first and second thermal conductivities of the first and second mold cavities, whereby compromises can be made regarding cooling loss in relation to the metal part with the desired rapid cooling of the mold for faster removal of the manufactured component.

[0009] In the process according to the invention, at least one plastic is injected into the injection mold and is arranged in contact with the at least one metal part. The term "plastic" in this application also includes mixtures of two or more plastics. Additives such as colorants, fillers, conductive materials, etc., may also be added to the plastic(s). Preferably, the at least one plastic is selected from the group consisting of polyphenylene sulfide, polyphenylene sulfone, polyphthalamide, polysulfone, polyimide, silicones, and / or mixtures thereof. Preferably, the melting point of the at least one plastic is in the range between about 200°C and about 310°C, more preferably between about 250°C and about 300°C, and particularly preferably between about 280°C and about 290°C. In one embodiment, the material of the at least one plastic is polyphenylene sulfide with a melting point of about 289°C.Preferably, the temperature of the at least one plastic during injection molding is between approximately 240°C and approximately 360°C, more preferably between approximately 270°C and approximately 350°C, and particularly preferably between approximately 280°C and approximately 340°C, provided that the injection molding temperature is higher than the melting point of the at least one plastic. In the embodiment where polyphenylene sulfide is used as the plastic, the injection molding temperature is in the range of approximately 310°C to approximately 360°C. This higher injection molding temperature ensures a viscosity necessary for the at least one plastic to flow sufficiently during injection to bond securely and fluid-tightly with the at least one metal part.To ensure good wettability of the macrostructures and their filling, a high melting temperature and consequently low viscosity are preferred. Injection molding produces at least one, preferably exactly one, plastic part. Preferably, the at least one plastic part has a wall thickness in the range of approximately 0.1 mm to approximately 50 mm, more preferably between approximately 0.5 mm and approximately 35 mm, and most preferably between approximately 2 mm and approximately 4 mm.

[0010] Preferably, the at least one metal part is heated before and / or during the injection of the at least one plastic. According to the invention, the temperature of the metal part is above the melting point of the at least one plastic. This prevents a solidified surface film from forming on the metal part when the polymer is injected. Preferably, the temperature of the metal part is higher than the temperature of the at least one plastic during injection, and thus above the melting point or melting range of the at least one plastic. This prevents a surface film from forming when the at least one plastic comes into contact with the at least one metal part. The at least one plastic has sufficient viscosity, even when it comes into contact with the metal part, to penetrate undercuts in the surface of the at least one metal part.This ensures good adhesion between the at least one metal part and the at least one plastic part. The at least one plastic part is sufficiently fluid during injection molding. Preferably, the at least one metal part and the at least one plastic part formed from the at least one plastic part, produced using the inventive method, form an adhesive, fluid-tight bond after cooling. Preferably, the adhesive bond between the at least one metal part and the at least one plastic part is formed on at least one connection area of ​​the at least one metal part. Preferably, the at least one metal part has a micro- and / or nanostructure configured such that undercuts are formed in the surface of the at least one metal part, whereby the micro- and nanostructures can also overlap.

[0011] The inventive method for producing injection-molded components can comprise the following steps: - Inserting at least one metal part into the first mold cavity part or the second mold cavity part, - Closing the two mold cavities to form a casting mold, creating a cavity for the injected plastic, - Heating at least one metal part to the metal part temperature, - Heating the at least one plastic to a temperature above its melting temperature or melting range to enable injection of the at least one plastic into the mold, - Injecting the melt of at least one plastic into the cavity, - Cooling the at least one plastic in the mold for a certain period of time so that it can cool down and solidify, - Opening the mold with the first and second mold cavity parts, - Removal of the injected component.

[0012] Preferably, a cavity is defined by the space between the first mold cavity part and the second mold cavity part, which is not occupied by the metal part(s). Preferably, the cavity comprises at least one recess or cavity in the first mold cavity part and / or at least one recess or cavity in the second mold cavity part.

[0013] If the first thermal conductivity of the first mold cavity part and / or the second thermal conductivity of the second mold cavity part are high, the cooling of the at least one plastic component can be accelerated. If the first thermal conductivity of the first mold cavity part and / or the second thermal conductivity of the second mold cavity part are low, the cooling of the at least one plastic component is slowed down. In an embodiment with different thermal conductivities of the first and second mold cavity parts, the cooling of the at least one plastic component can therefore preferably be set to be rapid while simultaneously keeping the heat loss of the at least one metal component relatively low.

[0014] The present invention further relates to an injection-molded component obtainable by the method described above, wherein the at least one metal part and at least one plastic part formed from the at least one plastic are bonded together. Preferably, the at least one metal part and the at least one plastic part have a micro- or nanostructure at least on a partial surface of the same. Preferably, the bond is permanent. Due to the mechanical interlocking of the nano- and / or microstructures, separation of the at least one metal part and the at least one plastic part is virtually impossible, in particular not without damaging the other part. Preferably, the bond is gas-tight.

[0015] The present invention further relates to the use of the injection-molded component as a battery terminal seal.

[0016] The present invention further relates to a device for producing injection-molded components using the method described above, comprising an injection mold which includes a first mold cavity and a second mold cavity and at least one induction element. Preferably, the device includes an outer and / or an inner induction element. Preferably, at least two induction elements are provided. The geometry and size of the induction element are selected depending on the metal parts to be heated. It is preferably movable, controllable, and / or adjustable. The at least one induction element preferably comprises a three-layer induction coil. Preferably, the at least one induction element has a power dissipation in the range of approximately 8 kW to 15 kW. Preferably, the at least one induction element has an exposure time in the range of approximately 0.5 s to 2 s.Preferably, the at least one induction element has a frequency in a range between approximately 15 Hz and 40000 Hz.

[0017] Further advantageous embodiments are shown in the following drawings. Identical parts or parts with the same function have the same reference numerals. They show: Fig. 1.1 A first embodiment of a device for producing injection-molded components using the inventive method in a perspective exploded view; Fig. 1.2 the first embodiment of a device for the production of injection-molded components according to Fig. 1.1 in a side section in the assembled state; Fig. 1.3 the first embodiment of a device for the production of injection-molded components according to Fig. 1.1 in a side section in exploded view; Fig. 1.4 injection-molded component obtainable using the inventive method with the device according to Fig. 1.1; Fig. 2.1 a second embodiment of a device for producing injection-molded components using the inventive method in a perspective exploded view; Fig. 2.2 the second embodiment of a device for manufacturing injection-molded components according to Fig. 2.1 in a side section in the assembled state; Fig. 2.3 the second embodiment of a device for manufacturing injection-molded components according to Fig. 2.1 in a side section in exploded view; Fig. 2.4 injection-molded component obtainable using the inventive method with the device according to Fig. 2.1.

[0018] Fig. Figure 1.1 shows a first embodiment of a device for producing injection-molded components using the method according to the invention. Fig. Figure 1.1 shows a first mold cavity part 30 and a second mold cavity part 32. In this embodiment, the first mold cavity part and the second mold cavity part are made, for example, of zirconium oxide. In this embodiment, the first thermal conductivity of the first mold cavity part 30 and the second thermal conductivity of the second mold cavity part 32 are, for example, about 2 W / m*K. In this embodiment, the first mold cavity part temperature and the second are, for example, about 100°C at the time of injection of a plastic. The first mold cavity part 30 has a recess 34. The second mold cavity part 32 has a recess 36. The recess 34 of the first mold cavity part 30 and the recess 36 of the second mold cavity part 32 are shaped differently. Fig. Figure 1.1 shows a first metal part 20 and a second metal part 22.

[0019] The first metal part 20 and the second metal part 22 are heated by induction using an induction element 40. In this embodiment, the temperature of the first metal part 20 and the second metal part 22 is approximately 360 °C. In this embodiment, the first metal part 20 is made of copper. In this embodiment, the second metal part 22 is made of aluminum. In this embodiment, the first metal part 20 has a wall thickness of approximately 0.5 mm and the second metal part 22 has a wall thickness of approximately 0.9 mm. The first metal part 20 and the second metal part 22 have a nanostructure in the connection areas 21a, 21b, 23a, 23b of the metal part, which is configured such that undercuts are formed in the surface of the metal parts. Fig. Figure 1.1 shows the finished plastic part 10, shown for clarity without connection to the first and second metal parts 20 and 22. In this embodiment, the plastic is polyphenylene sulfide. The manufactured plastic part has a wall thickness of approximately 1 mm. The melting point of the plastic is approximately 289°C. In this embodiment, the temperature of the plastic during injection molding is approximately 330°C. The temperature of the metal parts, at 360°C, is above the melting point of the plastic and thus above the temperature of the plastic during injection molding. This prevents the formation of a surface film. The component 100 produced by the inventive method exhibits good adhesion between the metal parts 20 and 22 and the plastic part 10; these are fluid-tightly connected to one another.

[0020] Fig. 1.2 and Fig. 1.3 show the same embodiment as Fig. 1.1. The induction element 40 surrounds the mold cavities 30 and 32 and is arranged at the level of the injection-molded component 100. The injection-molded component 100 consists of two metal parts 20, 22 and one plastic part 10. The injection-molded component 100 is arranged between the first mold cavity 30 and the second mold cavity 32. Fig. Figure 1.2 shows the state after injection of the plastic during cooling in the closed mold. In this embodiment, the injection-molded component is arranged horizontally. In this embodiment, the second metal part 22 was arranged in the recess 36 of the second mold cavity 32. The first metal part 20 was arranged on a raised section of the second mold cavity 32. After closing the mold, heating it, and heating the metal parts 20 and 22 as described above, the molten plastic was injected into the cavity formed between the first and second mold cavities 30 and 32. Thanks to the nanostructure of the connecting areas 21a, 21b, 23a, and 23b of the first metal part 20 and the second metal part 22, the metal parts 20 and 22 and the plastic part 10 are in an adhesive bond.

[0021] Fig. Figure 1.4 shows an injection-molded component 100. The injection-molded component is produced using the inventive method with the device shown in Figure 1.4. Fig. 1.1. A first metal part 20, a second metal part 22, and a plastic part 10 are bonded together. The first metal part 20, the second metal part 22, and the plastic part 10 each have a micro- or nanostructure on at least a portion of their surface, particularly on the connection areas 21a, 21b, 23a, and 23b. The bond is permanent. Due to the mechanical interlocking of the nano- and / or microstructures, separation of the at least one metal part and the at least one plastic part is virtually impossible, especially without damaging the other part. Fig. 2.1 shows a first embodiment of a device for producing injection-molded components using the method according to the invention. Fig. Figure 2.1 shows a first mold cavity part 30 and a second mold cavity part 32. In this embodiment, the first mold cavity part 30 is made, for example, of zirconium oxide. In this embodiment, the first thermal conductivity of the first mold cavity part is approximately 2 W / m*K. In this embodiment, the first mold cavity temperature is, for example, approximately 100°C at the time of injection of a plastic. In this embodiment, the second mold cavity part 32 is made, for example, of silicon nitride. In this embodiment, the second thermal conductivity of the second mold cavity part is, for example, approximately 35 W / m*K. The first mold cavity part 30 has a recess 34. The second mold cavity part 32 has a recess 36. The recess 34 of the first mold cavity part 30 and the recess 36 of the second mold cavity part 32 are shaped differently. Fig. Figure 2.1 shows a metal part 20. The metal part 20 is heated by induction using an induction element 40. In this embodiment, the metal part temperature is approximately 360 °C. In this embodiment, the metal part 20 is made of copper. In this embodiment, the metal part 20 has a wall thickness of approximately 0.5 mm. The metal part 20 has a nanostructure in the connection areas 21a, 21b of the metal part, which is designed such that undercuts are formed in the surface of the metal parts. Fig. Figure 2.1 shows the manufactured plastic part 10, shown for clarity without connection to the metal part 20. In this embodiment, the plastic is polyphenylene sulfide. In this embodiment, the manufactured plastic part has a wall thickness of approximately 1 mm. The melting point of the plastic is approximately 289°C. In this embodiment, the temperature of the plastic during injection molding is approximately 330°C. The temperature of the metal part, at approximately 360°C, is above the melting point of the plastic and thus above the temperature of the plastic during injection molding. This prevents the formation of a surface film during injection molding. The component 100 produced by the inventive method exhibits good adhesion between the metal part 20 and the plastic part 10; these are fluid-tightly connected to each other.

[0022] Fig. 2.2 and Fig. 2.3 show the same embodiment as Fig. 2.1. The ring-shaped, spirally formed induction element 40 surrounds the mold cavities 30 and 32 in the area of ​​the recesses 34, 36 thereof and is arranged at the level of the injection-molded component 100. The injection-molded component 100 consists of a metal part 20 and a plastic part 10. The injection-molded component 100 is arranged between the first mold cavity 30 and the second mold cavity 32. Fig. Figure 2.2 shows the state after injection of the plastic during cooling in the closed mold. In this embodiment, the injection-molded component is arranged horizontally. In this embodiment, the first metal part 20 was positioned on a raised section of the second mold cavity 32. After closing the mold, heating it, and heating the metal part 20 as described above, the molten plastic was injected into the cavity formed between the first and second mold cavities 30, 32. Thanks to the nanostructure of the connection areas 21a, 21b of the metal part, the metal part 20 and the plastic part 10 are in an adhesive bond.

[0023] Fig. Figure 2.4 shows an injection-molded component 100. The injection-molded component is produced according to the inventive method using the device shown in the illustration. Fig.2.1. A metal part 20 and a plastic part 10 are bonded together. The metal part 20 and the plastic part 10 have a micro- or nanostructure on at least a portion of their surface, particularly on the connection areas 21a, 21b. The bond is permanent. Due to the mechanical interlocking of the nano- and / or microstructures, separation of the at least one metal part and the at least one plastic part is virtually impossible, especially without damaging the other part. Reference symbol list 10 plastic parts 20 first metal part 21a First connection area of ​​the first metal part 21b second connection area of ​​the first metal part 22 second metal part 23a First connection area of ​​the first metal part 23b second connection area of ​​the first metal part 30 first mold cavity part 32 second mold cavity part 34 Deepening of the first mold cavity part 36 Deepening of the second mold cavity part 40 Induction element 100 injection-molded components

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