DE202019103482U1 - Sealing shell and its use, device for producing molded foam parts, foam mold and foam molding tool, and molded foam tool - Google Patents

Abstract

Sealing shell (101) for partially delimiting and for sealing a cavity (111), with a foam mold side and a tool carrier side, the sealing shell (101) being made of a material which compresses when the cavity (111) is closed.

Description

The invention relates to a sealing shell for partially delimiting and for sealing a cavity with a foam mold side and a tool carrier side, and a use of the sealing shell. The invention further relates to a foam mold and an associated foam mold.

When manufacturing foamed parts, varnishes are used to achieve a closed surface for the foamed parts. These coatings are also known as coatings. Here, a varnish made mostly of polyurethane (PU) is introduced into the open lower part of the foam mold. Then foaming is carried out and the foaming tool is closed. The foam system combines homogeneously with the paint and the part is then removed from the mold after the curing time. In a conventional production of the parts, the paint combines with the foam molding tool and the foaming tool must therefore be provided with a release agent before the foaming process.

Depending on the design of the foaming part, this can only be done in the lower part of the foaming tool or also on both sides, ie in the lower part of the foam mold and the upper part of the foam mold. The release agent causes quality losses on the surface of the finished foam parts, for example in the form of streaks, gloss differences, release agent inclusions or the like.

After a relatively small number of pieces, the release agent, which has built up in the foam tool during each cycle, must be removed by cleaning. This causes high waste and considerable costs.

The same applies to vehicle components such as armrests, which are usually made of a plastic inlay or carrier and which are connected to foam in a defined area. In most cases, foam components are produced in a front foam mold through a cavity in the lower part, the front foam mold largely consisting of aluminum.

Furthermore, the plastic carrier can be produced in that the plastic inlay or the plastic carrier is fixed in the upper part of the foaming tool and the upper part and lower part are closed, the foam system having been introduced into the lower part beforehand. The foaming system fills the cavity created by the closing of the lower and upper part between the lower part of the foaming tool and the carrier surface of the plastic inlay or the plastic carrier. The foam system connects homogeneously with the plastic inlay or the plastic carrier.

The resulting component is usually laminated later. When laminating, for example, a film or leather is stretched over the foam area of the component and connected to the component, for example by sewing.

The quality of the components described above crucially depends on an invisible transition between the plastic carrier and the flexible foam after lamination.

Furthermore, foam systems have the property of penetrating even the smallest gaps between the carrier and the foam shape, even with a size smaller than 0.05 mm, due to their expansion behavior. This behavior is known as "overexposure". This foam must be removed manually after manufacture or with the aid of robot-assisted grinding tools or brushes.

In order to reduce this foaming, the plastic inlay or the plastic carrier is brought into contact with the lower part of the foaming tool as defined as possible. This contacting is called inking. However, due to manufacturing tolerances in the plastic inlay or the plastic carrier, this contact does not lead to a sealed cavity, so that foaming continues frequently.

The plastic inlay or the plastic carrier cannot be pressed on, since this scratches or damages the sensitive lower parts of the foaming tool, rendering them unusable.

As has already been shown, components made of plastic carriers and the foam attached to them are laminated. Depending on costs and haptic and optical properties, this can be done using a film, a stretched plastic skin or leather. Each of these lamination materials can have a different thickness, which means that different foam shapes have to be used for different lamination materials.

The object of the invention is to improve the prior art.

According to a first aspect of the invention, this object is achieved by a sealing shell for partially delimiting and sealing a cavity, with a foam mold side and a tool carrier side, the sealing shell being made from a material which compresses when the cavity is closed.

A foam mold can thus be provided, in which a plastic carrier or a Push the plastic inlay a little into the sealing shell without damaging it mechanically or abrasively.

A circumferential, closed contour can thus be created, which means that foaming no longer occurs. A sealed cavity can thus be provided.

The following terms are explained:

A “sealing shell” forms a flat, three-dimensional boundary for foam that is introduced into the cavity. The sealing shell is regularly attached in a foaming tool. The use of the sealing shell is advantageous in that the sealing shell is simple to manufacture and can be replaced quickly and inexpensively in the event of damage.

The sealing shell can develop foam-repellent properties, so that the use of release agents is not required in a preferred embodiment.

The basic manufacture, use of the sealing shell in a foam tool and the release agent-repellent manufacturing features can WO 2010 13 93 07 A1 are removed, the relevant content being part of the present application.

The "partial limitation" refers to the spreading of a foam inserted into the cavity, so that the shape of the sealing shell is simulated by the inserted expanding foam.

“Sealing a cavity” is to be understood in particular to mean that the foam at the contact contour is not foamed or is greatly reduced.

A "cavity" is a cavity which is filled in by an inserted foam and which imprints the shape of the cavity itself.

The "molded foam side" of the sealing shell is the area of the sealing shell that can come into contact with the expanding foam.

The "tool carrier side" of the sealing shell is the part of the sealing shell that is in fixed contact with the foam tool.

The “compressible material” is designed in such a way that, for example, when a plastic carrier is pressed on, the manufacturing tolerance of the plastic carrier is compensated for by compressing the material.

The selection of the material and the pressure required to produce the sealed cavity is determined in particular by the fact that different materials with different thicknesses are subjected to the maximum permissible tolerance deviations of the plastic carrier under pressure, so that no foaming occurs in the foam used. A selection of the material, the material thickness and the pressure is essentially empirical.

In order to imprint a defined structure on the foam molding, the sealing shell can have a grain, a smooth or a polished surface on the foam mold side.

A “grain” is to be understood as meaning a surface with a contour embossed, for example to imitate a leather-like structure. A grained surface can thus convey a high haptic quality to the molded foam part.

In a further embodiment, the sealing shell can be produced by means of an injection molding process or by means of a deep-drawing process. This means that sealing shells can be produced in large quantities with the same quality.

Sealing shells are preferably produced that have a thickness that is repeatable to within a hundredth of a millimeter.

In addition, a grained surface can already be produced by the manufacturing process of the sealing shell and does not have to be stamped on the foam shape separately, for example by photoetching.

In order to provide an optimal material for the sealing shell, the sealing shell can be made of a material which has a polyolefin, in particular a polyethylene, or a thermoplastic elastomer.

Polyolefins are polymers which are produced from alkenes, such as ethylene, propylene, 1-butene or isobutene, by polymerization. Polyolefins are also known as polyalkenes. Polyolefins comprise saturated hydrocarbons and form partially crystalline thermoplastics, which are particularly suitable for the injection molding process. They are characterized by good chemical resistance and electrical insulation properties.

“Polyethylene” is a thermoplastic made by polymerizing ethylene [CH ₂ = CH ₂ ] with the simplified chain structural formula [-H ₂ C-CH ₂ -] _n .

Thermoplastic elastomers (TPE) are plastics that behave comparable to classic elastomers at room temperature, but can be plastically deformed when heated and thus show thermoplastic behavior. Thus, the compression behavior of the sealing shell can be influenced in particular by a defined temperature control.

Thermoplastic elastomers are materials in which elastic polymer chains are integrated in the thermoplastic material. They can be processed in a purely physical process in a combination of high shear forces, exposure to heat and subsequent cooling. Although no chemical crosslinking due to time-consuming and temperature-consuming vulcanization, as with the elastomers, is necessary, the sealing shells produced have rubber-elastic properties due to their special molecular structure.

In some areas, thermoplastic elastomers have physical crosslinking points that dissolve when heated without the macromolecules decomposing. For this reason, these are easier to process than "normal elastomers". The thermoplastic elastomers include both the block copolymers and elastomer alloys. Block copolymers have hard and soft segments within a molecule. The plastic consists of one type of molecule in which both properties are distributed.

Elastomer alloys are considered poly blends, i.e. mixtures of finished polymers. The plastic can therefore consist of several types of molecules. Due to different mixing ratios and additives, customized materials are obtained. Examples of this are polyolefin elastomer made of polypropylene and natural rubber, which cover different hardness ranges depending on the quantity composition. Thermoplastic elastomers include TPE-O (olefin-based thermoplastic elastomers), TPE-V (cross-linked olefin-based thermoplastic elastomers), TPE-U (urethane-based thermoplastic elastomers), TPE-E (thermoplastic polyester elastomers / thermoplastic copolyesters), TPE-S (Styrene block copolymers (SBS, SEBS, SEPS, FEEPS and NBS) such as Septon from Kuraray) and TPE-A (thermoplastic copolyamides).

So that a protective surface can be embossed on the foam, the sealing shell is at least partially covered with a varnish. Paints of the type used here are in particular paints based on polyurethane.

In a further embodiment, a carrier, in particular a plastic carrier, or a tool half of the sealing shell can be pressed on, so that a foam-tight contact contour is formed.

Thus, a cavity for a foam can be provided, which forms the shape of the sealing shell on one side and forms a firm contact with the carrier on the other side or imprints the shape of the mold half on the foam. In particular, foaming over the contact contour is prevented.

In order to also provide the advantages of the sealing shell to a second tool half, the (second) tool half can have a (second) sealing shell, in particular it is a sealing shell as described above.

In particular, the second sealing shell can have a different material composition than a first sealing shell, so that, for example, a harder sealing shell can be joined together with a softer sealing shell to form a sealed cavity. It should be pointed out here that a sealing shell can be inserted in each half of the foaming tool.

Since venting via the contact contour should not take place, or should take place only with difficulty, at least one of the sealing shells, the carrier or one half of the tool can usually have a venting area in a non-visible area. The exact location of the ventilation area is regularly empirically determined.

In order to trap foamed material, one of the sealing shells, the carrier or the tool half can have a ventilation pot. In this way it can be ensured that foamed material of the cavity is placed in a ventilation pot in a defined manner.

Furthermore, the venting pot can have a sealing lip, so that the venting area and thus the venting pot is hermetically sealed against the environment.

In a further embodiment of the invention, the ventilation area can be designed semi-permeable, so that a foam expanding in the cavity remains and air leaves the cavity via the semi-permeable ventilation area.

Air pockets in the foam can thus be reduced. Furthermore, the air in the cavity is not compressed excessively, so that a higher quality in relation to the foam molded parts can be guaranteed.

In order to implement the most effective and easily realizable possibility of the semi-permeable ventilation area, the semi-permeable ventilation area can be formed by a vapor diffusion-open membrane or by micro-bores.

The “membrane open to vapor diffusion” can in particular be designed as a lattice which has small holes at regular or irregular intervals. Thus, this can be a PE grid, for example, which has holes in the micro or nano range.

The “micro bores” can in particular already be created during the manufacturing process of the sealing shell or can be made available through bores in the manufactured sealing shell. Both the micro bores and the grid openings can be made smaller than 0.05 mm, in particular smaller than 0.01 mm or smaller than 0.003 mm.

In a further embodiment, the sealing shell is fixed in a foam tool on the tool carrier side, so that a foam tool is formed with a sealing shell.

Thus, a device can be provided with which molded foam parts, in particular from the carrier and attached foam, can be produced.

In order to ensure that the sealing shell is held in a foaming tool as simply and effectively as possible, it can be fixed by means of a vacuum or mechanically.

With "mechanical fixing", both releasable fixed and fixed connections can be implemented. The possibilities of fastening are not limited to screws, gluing or clamping.

When "fixing by means of a vacuum", a form-fitting receptacle can be used for the sealing shell, with several holes being arranged in the receptacle. A vacuum is created behind these holes so that the sealing shell is pressed into the receptacle.

In a further aspect of the invention, the object is achieved by a device for producing molded foam parts, a previously described sealing shell being introduced. A molded foam part tool can thus be provided which implements the advantages already described.

In an additional aspect of the invention, the object is achieved by using a sealing shell described above to compensate for differences in thickness of foamed molded parts, which are, for example, leather-clad and foil-clad. Differences in thickness can thus be compensated for by the sealing shell.

In addition, the "Pure Liner" used up to now are no longer necessary. The "Pure Liner" is an additional layer that has previously achieved the thickness compensation. The disadvantage here was that the Pure Liner often remained in the component and the lamination was carried out around the Pure Liner. Such solutions are no longer necessary in the present case and a high production rate with high quality requirements can be provided.

In a further aspect, the object is achieved by a foam mold with a semi-permeable ventilation area.

In this way, foam molds can generally be provided with an effective venting device. The advantages correspond to the previously described advantage in the case of semi-permeable ventilation areas in the previously described sealing shell, the application not being limited to sealing shells but being usable in all foaming tools.

In relation to an embodiment in this regard, the semi-permeable ventilation area can be formed by a membrane or by micro-bores. For this purpose, reference is also made to the properties and advantages described above.

Furthermore, the object can be achieved by a molded foam tool which has a previously described molded foam shape. Molded foam tools of high quality and quality can thus be provided.

In a further aspect of the invention, the object is achieved by a method for producing a foam mold, wherein a sealing shell described above is used and a counterpart of the sealing shell is pressed onto the sealing shell to form a sealed cavity, and a foam is pressed into the cavity before or after being pressed on is introduced so that the sealed cavity is formed and the foam introduced into the cavity only expands within the cavity.

The counterpart can be formed by a further sealing shell.

Both the material thickness and the material selection as well as the forces required to form the sealed cavity are determined empirically.

This means that foam molds and foam molded parts of high quality and quality can be provided.

In a further aspect of the invention, the object is achieved by a molded foam part which is produced by the previously described method.

The invention is explained in more detail below on the basis of exemplary embodiments.

• 1 in einer schematischen Schnittzeichnung ein Schäumwerkzeug mit einem eingebrachten Kunststoffträger.

The shows

• 1 in a schematic sectional drawing of a foaming tool with an inserted plastic carrier.

A tool for producing a molded foam part is provided in that in a tool carrier half 109 a sealing cup 101 is inserted. The inclusion of the tool carrier half 109 has vacuum holes 113 on. The tool carrier 109 has a cavity 114 on. A vacuum pump is attached to this cavity 115 flanged. About that through the vacuum pump 115 created vacuum in the tool holder cavity 114 is about the vacuum holes 113 the sealing cup 101 in the tool carrier half 109 fixed.

The molded foam part to be produced has a plastic carrier 103 on. The plastic carrier 103 has a vent hole on the cavity side 123 on which of the cavity 111 in the vent pot 117 leads. The vent pot 117 is over a sealing lip 119 firmly with the plastic carrier 103 connected. In addition, the vent pot 117 a semipermeable membrane 121 on. This semipermeable membrane 121 consists of GoreTex®. This allows air to escape from the cavity 111 to the vent pot 117 transported and across the membrane 121 be dissipated.

Before the molded foam part can be produced, a lacquer is applied on the cavity side 125 based on polyurethane on the sealing shell 101 applied. In the cavity 111 a foam is introduced which expands over time. Immediately after the foam has been introduced, the plastic carrier is pressed into the sealing shell with a defined force F in the direction of the arrow 101 pressed.

This forms at the contact points 105 . 107 a contact contour. Because the plastic carrier edge 105 the contact edge of the sealing shell 107 elastically deformed, becomes a closed and foam-tight cavity 111 provided. In this cavity 111 the previously inserted foam expands.

Since foaming over the contact contour is not possible, excess foam gets into the vent pot 117 , In addition, the vent hole 123 and the membrane 121 Air from the cavity 111 away.

When the previously introduced foam is foamed, the shape of the cavity changes 111 imprinted on the foam. The foam forms with both the paint 125 as well as with the plastic carrier 103 a firm connection.

After foaming is completed, the molded foam part consists of a plastic carrier 103 , foamed foam and coated paint 125 removed from the mold.

Due to the choice of material for the sealing shell, this molding takes place without residue. This is followed by a further production of a molded foam part. Alternatively, the closed cavity 111 formed and the foam then introduced.

So that a molded foam part can be laminated with materials of different thicknesses, the thickness of the sealing shell 101 selected such that the differences in thickness of the laminating materials are balanced.

The present sealing shell 101 is made from a mixture of TPE-O with natural rubber (NR). The natural rubber content varies between 15% and 40%. To determine the force F with which the plastic carrier 103 on the sealing cup 101 is pressed, two plastic carriers 103 selected with the two extreme values of the tolerance range. In each case, the force is determined which is necessary to obtain a closed contour, with no foaming. The higher value for F is used below.

In a second alternative (not shown), the vent pot has 117 no membrane on. However, are in the sealing cup 101 Openings with a diameter of 0.01 mm are arranged. This allows air to escape from the closed cavity 111 escape through these holes.

A third alternative is in the sealing cup 101 a semipermeable membrane 121 arranged. In this case, the mode of operation is as previously described, with air flowing over that in the sealing shell 101 arranged membrane takes place.

In a fourth alternative, the cavity 111 not have a plastic carrier 103 closed, but via a further (second) tool half, in which a second sealing shell is arranged. This creates molded parts that simulate the cavity. It should be noted that a closed contour is also guaranteed, over which no foaming takes place, but air is discharged from the cavity via a ventilation area with a membrane or microbores.

With the present sealing shell 101 spray skins are also produced. The sealing shells used for this 101 have a positive grain, which the sealing shells 101 were already stamped during injection molding at the time of manufacture. The spray skin then produced accordingly has the desired surface.

The shell is placed in a tool carrier as previously described. No release agents are required in the manufacturing process, since the sealing shell already has a separating effect inherent in the material.

To produce the spray skins, two components are mixed in a mixing nozzle and sprayed onto the sealing shell using a robot. Spray skins of desired thicknesses can thus be produced.

In a further alternative, the present sealing shells are also used in the production of epoxy resin components, such as, for example, skis, surfing or ship parts. Accordingly, the epoxy resin and the corresponding matrices such as glass fiber mats are inserted into the sealing shell.

LIST OF REFERENCE NUMBERS

101

seal tray

103

Plastic carrier

105

Plastic carrier edge

107

Contact edge of the sealing shell

109

Tool carrier half

111

Closed cavity

113

vacuum holes

114

Tool holder cavity

115

vacuum pump

117

Air vent trap

119

sealing lip

121

membrane

123

vent hole

125

paint layer

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2010139307 A1 [0020]

Claims (18)

Sealing shell (101) for partially delimiting and for sealing a cavity (111), with a foam mold side and a tool carrier side, the sealing shell (101) being made of a material which compresses when the cavity (111) is closed. Sealing shell (101) for partially delimiting and for sealing a cavity (111), with a foam mold side and a tool carrier side, the sealing shell (101) being made of a material which compresses when the cavity (111) is closed, characterized in that that the sealing shell (101) is configured in two parts; Consisting of an underside with which a lower foam tool can be partially limited and sealed, and an upper side with which an upper foam tool can be partially limited and sealed. Sealing shell (101) according to one of the preceding claims, characterized in that the sealing shell (101) has a grain, a smooth or a polished surface on the foam shape side. Sealing shell (101) according to one of the preceding claims, characterized in that the sealing shell (101) can be connected to the foaming tool at least via a releasably fixed connection. Sealing cup according to one of the Claims 1 - 3 , characterized in that the sealing shell (101) can be connected to the foaming tool at least via a fixed connection. Sealing shell (101) according to one of the preceding claims, characterized in that the sealing shell (101) is produced by means of an injection molding process or by means of a deep-drawing process. Sealing shell (101) according to one of the preceding claims, characterized in that the sealing shell (101) is made of a material which has a polyolefin, in particular a polyethylene, or a thermoplastic elastomer. Sealing shell (101) according to one of the preceding claims, characterized in that the sealing shell (101) is at least partially covered with a lacquer. Sealing shell (101) according to one of the preceding claims, characterized in that a carrier, in particular a plastic carrier (103), or a tool half of the sealing shell (101) is pressed on, so that a foam-tight contact contour is formed. Sealing cup (101) Claim 8 , characterized in that the sealing shell (101), the carrier or the tool half has a ventilation area in a non-visible area. Sealing shell (101) according to one of the preceding claims, characterized in that the sealing shell (101), the carrier or the tool half, has a venting pot (117). Sealing shell (101) according to one of the preceding claims, characterized in that the sealing shell (101) has a venting pot (117) with a sealing lip (119). Sealing shell (101) according to one of the preceding claims, characterized in that the ventilation area is semipermeable, so that a foam expanding in the cavity (111) remains in the cavity (111) and air leaves the cavity (111) via the semi-permeable ventilation area. Sealing cup (101) Claim 13 , characterized in that the semi-permeable ventilation area is formed by a membrane (121) or by micro-bores. Foaming tool, characterized in that a sealing shell (101) is fixed in the foaming tool on the tool carrier side. Foaming tool after Claim 15 , characterized in that the sealing shell (101) is fixed by means of a flat vacuum or mechanically. Mold foam tool, which is a foam mold according to one of the Claims 15 - 16 having. Foam molding, characterized in that it has a foam shape according to one of the Claims 15 - 16 is made.

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