Tool and method for producing a coated plastic component

Abstract

Tool for producing a coated plastic component from a component core (10) and a coating (11), wherein the tool comprises a first tool half (21) and a second tool half (22), wherein the first tool half (21) and the second tool half (22) form a cavity between them and a removable mold mask (23), a first region and a second region (24) are provided in the cavity, wherein the first area is intended to accommodate the component core (10), the second region (24) is intended to receive the coating (11) or a place-holding material and is directly adjacent to the first region and the mold mask (23) directly adjoins the second region (24), at least partially encompasses the first and second regions and extends from the first tool half (21) into the second tool half (22).

Description

[0001] The invention relates to a tool and a method for the simple production of a coated plastic component in which the coating extends seamlessly over the visible area into a non-visible area.

[0002] Various processes and associated tools are already known from the prior art for producing coated plastic components. In most cases, a component core is produced using an injection molding process, for example, and removed from the injection molding tool, and then overmolded or painted in another tool. However, this process requires the use of at least two different tools, and long process times must be accepted due to demolding, i.e. removing the component core from the injection molding tool and inserting it into the tool to create the coating. In addition, the tools used to create a coating can usually only cover part of the visible area, or rather part of the visible area.of the visible area of ​​the component core, which is visible to an observer during the respective use, so that optically disadvantageous transitions, edges or ridges arise between different coatings or between a coating and the component core.

[0003] EP 2 420 372 A1 relates to a casting core comprising a core material which can be selectively solidified and softened, in particular liquefied, into a plastic deformation state and which is surrounded by a shell material, wherein the shell material is permanently solid and continuously coherent, regardless of the degree of solidification of the core material during normal operation of the casting core, and forms a soft-elastic and / or form-labile shell in which the core material is accommodated at least in the solid state and during a change in its degree of solidification towards and away from the solid state.

[0004] From DE 42 37 638 A1 it is known to use a mold with a melting core made of low-melting metal alloys, for example a bismuth-tin alloy, and a hollow mold enclosing the melting core for the production of prototypes or small series of a component made of thermoplastics having undercuts and / or a complicated geometry.

[0005] DE 3490046 T5 describes a method for producing a hollow plastic body.

[0006] WO 01 / 07227 A1 proposes a method for producing a hollow body, particularly by injection molding using the melt-core process. Furthermore, a corresponding device, a cooler, and a fuel rail produced using this process are protected. The cooler represents a double-walled hollow structure formed by providing a tubular insert in the melt core. This insert protrudes from the melt core and thus connects to the cooler housing. After the melt core has melted out, another hollow space is created, with connections provided for the passage of the cooling fluid and the fluid to be cooled. In this way, a highly reliable component can be produced cost-effectively, with complex component structures being able to be manufactured in a single operation.

[0007] The invention is therefore based on the object of overcoming the disadvantages described above and of providing a tool and a method with which a coated plastic component can be produced in a simple and rapid manner and whose coating extends seamlessly over the visible area of ​​the coated plastic component into the non-visible area of ​​the coated plastic component.

[0008] This problem is solved by the combination of features according to patent claim 1.

[0009] According to the invention, a tool for producing a coated plastic component is proposed. The plastic component is formed from a component core and a coating. The tool comprises a first tool half and a second tool half. The first tool half and the second tool half form a cavity between them. A removable mold mask, a first region and a second region are provided in the cavity. The first region is provided to receive the component core and the second region is provided to receive the coating or a placeholder material. The second region is directly adjacent to the first region. The mold mask is directly adjacent to the second region and at least partially encompasses the first and second regions. The mold mask extends from the first tool half into the second tool half.The mold mask extends over the entire visible area of ​​the plastic component to be produced and into the non-visible area. The non-visible area and the visible area of ​​the plastic component are opposite each other, so that the mold mask extends over the transition between the visible area and the non-visible area. The transition is preferably located at an edge of the component core. As a result, the mold mask encompasses both the first and the second area, particularly from the visible side across the transition to the non-visible area. The parting plane of the tool, i.e. the plane at which the tool is divided into the first and second tool halves, normally creates a clearly visible burr on the coated plastic component when the coated plastic component is demolded.Because the mold mask extends from the first to the second mold half, no burr is created in the parting plane of the coated plastic component. The burr is shifted by the mold mask toward the transition between the visible and non-visible areas, or into the non-visible area. If the burr coincides with an edge, the burr is completely concealed.

[0010] The first and second mold halves preferably rest on one another vertically, as an upper and lower mold half. Alternatively, the first and second mold halves can rest against one another horizontally. In addition to the first and second mold halves, the mold can comprise further mold components, wherein the cavity is formed by the first and second mold halves and at least some of the further components.

[0011] The mold mask can form a structure on its side facing the second region, so that the structure is transferred to the coating during injection and curing of the coating material. The surface of the coated component formed by the coating is determined by the mold mask or the structure of the mold mask.

[0012] In an advantageous further development, the mold mask is made of an elastic material, allowing it to be elastically deformed and moved relative to the tool or removed from the tool. An elastic mold mask can be reused because it determines the shape of the coating in the tool and can be separated from the coating and the tool without damaging it when removed from the tool.

[0013] A further advantageous embodiment provides that a means is provided on or in the mold mask for directly or indirectly controlling the temperature of the mold mask by heating or cooling. Such a means can be channels that conduct a temperature-controlled medium or heating elements. These means can be formed on or in the tool so that they pass the temperature on to the mold mask, which indirectly heats or cools the first and second regions in the cavity or heats or cools the coating or coating material in order to specifically control its curing. Alternatively, the means can also be arranged in the mold mask so that the mold mask can directly or immediately control the temperature of the first and second regions or the coating material by heating or cooling.

[0014] The invention further proposes a method for producing a coated plastic component in a tool according to the invention. The method comprises at least the following steps: a. Inserting the space-maintaining material into the second area; b. Inserting the component core into the first area; c. Injecting a coating material into the second region through an injection channel system in the tool and, beforehand or simultaneously, discharging the space-holding material from the second region through a discharge channel system in the tool. In addition, before discharging the space-holding material, the second region can also be cleaned, for example by air purging, in order to prepare the second region for the injection of the coating material to form the coating; d. Opening the tool by spacing or separating the first tool half from the second tool half; e. demoulding the coated plastic component from the cavity by deforming the mold mask, wherein the mold mask preferably emerges at least partially from the cavity.

[0015] A further development of the process also includes a mold mask tempering step, in which the cavity or coating material is brought to a predetermined temperature by heating or cooling the mold mask. The controllable temperature allows for targeted support and manipulation of the curing and injection of the coating material.

[0016] In an advantageous development of the method, the placeholder material is introduced into the second region by spraying it onto the mold mask. Alternatively, the placeholder material can be introduced into the second region as a dimensionally stable unit by inserting it into the mold mask.

[0017] If the placeholder material has a sufficiently low viscosity, it can be evenly distributed over the second area by swiveling the mold mask after the placeholder material has been introduced into the second area.

[0018] In an advantageous design variant, the placeholder material is oil, wax, sand or another viscous or semi-viscous material.

[0019] Alternatively or in addition to a placeholder material, the component core has a plurality of spacers protruding from the component core as placeholder material or in addition to the placeholder material. The spacers are formed integrally by the component core and are designed to be at least partially displaced into the component core when the coating material is injected. The spacers are further designed to maintain a distance between the component core and the mold mask so that the coating is formed on the component core in a predetermined layer thickness and the component core does not deviate from its predetermined position. When the coating material is injected, the spacers are pressed into the component core by the pressure generated in the second region by the injection so that the spacers do not visually disrupt the visible area of ​​the plastic component and the coating is formed evenly.The spacers are designed, for example, with predetermined breaking points surrounding their bases that yield at a predetermined pressure in the second region, so that as soon as the predetermined breaking point has yielded, the spacer is pressed into a recess formed directly beneath the respective spacer. The predetermined breaking points of different spacers can be designed with different strengths, so that the order in which they are pressed into the component core can be controlled.

[0020] In a preferred process variant, the component core is introduced by injecting a liquid plastic material into the first region and subsequently curing the plastic material in the first region. The subsequent injection of the coating material allows the coated plastic component to be formed entirely in one tool. This eliminates additional process times for demolding, transporting, inserting, and aligning the component core, simplifying the manufacturing process.

[0021] Alternatively, the component core can be introduced into the first area by inserting a previously manufactured component core.

[0022] In an advantageous process variant, the mold mask is elastically deformed when the mold is opened. This automatically demolds the coated plastic component when the mold is opened, i.e., when the first and second mold halves are separated.

[0023] Other advantageous developments of the invention are characterized in the subclaims or are presented in more detail below, together with the description of the preferred embodiment of the invention, with reference to the figures. They show: Fig. 1 a first step of a method according to the invention; Fig. 2 a second step of the method according to the invention; Fig. 3 a third step of the method according to the invention; Fig. 4 a tool according to the invention with a component core aligned by spacers.

[0024] The figures are schematic examples. Identical reference numerals in the figures indicate identical functional and / or structural features.

[0025] Fig. 1 shows a first step of a method for producing a coated plastic component. The component core 10 has already been introduced into the cavity formed by the first and second mold halves 21, 22 and overmolded with the coating material, so that the coating 11 has formed on the component core 10 and forms a unit with it. The coating 11 is formed between the component core 10 and the mold mask 23 and, together with the mold mask 23, surrounds an edge 10' of the component core 10. The component core 10 is thus completely covered by the coating 11 in its visible area. In the exemplary embodiment shown, the visible area is the surface of the component core 10 facing the first mold half 21 and merges into the non-visible area at the edge 10'.The mold mask 23 extends from the first mold half 21 into the second mold half 22 and encloses the component core 10 and the coating 11 on three sides. The mold mask 23 particularly covers the parting plane between the first and second mold halves 21, 22 and the coating 11, so that no visible seam or burr is created in the coating 11 and a uniform coating surface is formed. The mold mask 23 particularly encompasses the edge 10' of the component core 10, so that the coating 11 can form seamlessly between the component core 10 and the mold mask 23, even in the region of the edge 10'.

[0026] Once the coating 11 has cured to the extent that it is dimensionally stable, the coated plastic component, or the component core 10 with the coating 11, can be removed from the tool. For this purpose, as shown in Fig. As shown in Figure 2, the first tool half 21 is separated from the second tool half 22. Because the mold mask 23 encompasses the coating 11 and the component core 10, demolding of the coated component from the mold mask 23 or from the first tool half 21 is prevented.

[0027] By automatically moving the mold mask 23 out of the first tool half 21 when separating the first tool half 21 from the second tool half 22 and elastically deforming the mold mask 23, as shown in Fig. 3, the blocking effect of the mold mask 23 on the coated plastic component is eliminated, so that the component core 10 with the coating 11 is released from the mold mask 23 by itself or with the aid of gravity. As a result, the component core 10 with the coating 11 is demolded from the mold mask 23, and the tool can be used with the mold mask 23 to produce another coated plastic component.

[0028] Particularly with more complex shapes of the plastic component to be produced, it is sometimes necessary to keep the distance between the component core 10 and the mold mask 23 constant and to provide additional support. This is especially the case if the component core 10 cannot be fixed or aligned in the cavity in the conventional manner. Fig.4 shows an embodiment of the component core 10 in which a plurality of spacers 12 are formed integrally with the component core 10. The spacers 12 extend from the component core 10 to the mold mask 23 and thereby fix the component core 10 in the cavity. When the coating material is injected into the second region 24, an ever-increasing pressure builds up in the second region 24. The spacers 12 are designed such that, starting at a predetermined pressure in the second region 24, they are at least partially pressed into the component core 10, thereby allowing a uniform coating 11 to form towards the mold mask 23. For this purpose, cylindrical recesses are formed in the component core 10, in which the spacers 12 are received as soon as the pressure is high enough.In the embodiment shown, the spacers 12 are formed with predetermined breaking points running around their base on the component core 10, so that they give way under sufficiently high pressure and the respective spacer 12, whose predetermined breaking point has given way, is pressed into the cylindrical recess formed directly beneath the respective spacer 12.

[0029] For example, the second region could completely enclose the first region, with the component core being held in position by the spacers and the coating being produced in sections, with sections of the coating being melted by the section-by-section tempering of the mold mask in order to connect seamlessly with the additional sections of the coating. List of reference symbols 10 Component core 10' edge 11 Coating 21 first tool half 22 second tool half 23 Form mask 24 second area

Claims

[1] Tool for producing a coated plastic component from a component core (10) and a coating (11), wherein the tool comprises a first tool half (21) and a second tool half (22), wherein the first tool half (21) and the second tool half (22) form a cavity between them and a removable mold mask (23), a first region and a second region (24) are provided in the cavity, wherein the first area is intended to accommodate the component core (10), the second region (24) is intended to receive the coating (11) or a place-holding material and is directly adjacent to the first region and the mold mask (23) directly adjoins the second region (24), at least partially encompasses the first and second regions and extends from the first tool half (21) into the second tool half (22). [2] Tool according to claim 1, wherein the mold mask (23) is formed of an elastic material so that it is elastically deformable and movable relative to the tool. [3] Tool according to claim 1 or 2, wherein a means is provided on or in the mold mask (23) to directly or indirectly temper the mold mask (23) by heating or cooling. [4] Method for producing a coated plastic component in a tool according to at least one of the preceding claims, wherein the method comprises at least the following steps: a. introducing the space-holding material into the second region (24); b. introducing the component core (10) into the first region; c. injecting a coating material into the second region (24) and, beforehand or simultaneously, discharging the place-holding material from the second region (24); d. Opening the tool by spacing the first tool half (21) from the second tool half (22); e. demoulding the coated plastic component from the cavity by deforming the mold mask (23). [5] Method according to the preceding claim, wherein the method further comprises a step of tempering the mold mask (23) by heating or cooling the mold mask (23) to a predetermined temperature. [6] Method according to one of the preceding claims 4 or 5, wherein the place-holding material is introduced into the second region (24) by spraying onto the mold mask (23) or by inserting it into the mold mask (23). [7] Method according to one of the preceding claims 4 to 6, wherein the place-holding material is oil, wax, sand or another viscous or semi-viscous material. [8] Method according to one of the preceding claims 4 to 7, wherein the component core (10) has a plurality of spacers (12) protruding from the component core (10) as place-holding material or in addition to the place-holding material, which spacers are formed integrally by the component core (10) and are designed to be displaced at least partially into the component core (10) during the injection of the coating material and to maintain a distance of the component core (10) from the mold mask (23). [9] Method according to one of the preceding claims 4 to 8, wherein the component core (10) is introduced into the first region by injecting a liquid plastic material into the first region and subsequently curing the plastic material. [10] Method according to one of the preceding claims 4 to 8, wherein the component core (10) is produced and then introduced into the first region by inserting the component core (10). [11] Method according to one of the preceding claims 4 to 10, wherein the mold mask (23) is elastically deformed when the tool is opened and the coated plastic component is thereby demolded.

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