WO2007000132A1

WO2007000132A1 - Method for producing a foam moulded body

Info

Publication number: WO2007000132A1
Application number: PCT/DE2006/001012
Authority: WO
Inventors: Hannes Lüdtke
Original assignee: Intier Automotive Interiors Gmbh
Priority date: 2005-06-25
Filing date: 2006-06-13
Publication date: 2007-01-04
Also published as: DE102005029584A1; DE112006002357A5

Abstract

The invention relates to a method for producing a foam moulded body (6) in a foam shaping tool (1). A cavity (3), which is formed by the foam shaping tool (1), is filled by means of a suitable foamed material (4) having a closed-pore outer skin. The foamed cavity (3) is impinged upon after the foam material (4) is hardened and prior to the foam moulding body (6) being received. A carrier (2) is arranged in the foam shaping tool prior to foaming. A gaseous or liquid pressure medium is introduced into the cavity (3) for the pressurising thereof. Pressurisation increases in a stepped or continuous manner until a predetermined maximum pressure is attained. A counter force balancing the pressure of the cavity (3) is exerted on the carrier (2). The cavities (3) on two adjacent foam shaping tools (1), which interact with the respective carrier (2), can be simultaneously and constantly impinged upon, such that one carrier (2) works against a displacement of the other carrier (2).

Description

Process for the preparation of a foam molding

Description

The invention relates to a method for producing a

A foam molding having a closed-pore outer skin in a foam molding tool, wherein a suitable foam material is introduced into a cavity formed in the foam molding tool and foamed.

It is known, for example, to produce decorative moldings for the interior trim of motor vehicles from suitable plastic foams or to coat a shaping carrier with a plastic foam in order to enable an appealing surface design and feel of the decorative molding used for the interior trim of the motor vehicle.

Integral foams are known whose surface, during the setting of the foam through contact with the foaming mold, forms a skin which forms a closed and resistant surface. Such integral foams enable the production of a foam molding with essentially a single process step. It is also known to first make a skin adapted to the visible outside of the decorative molding and to insert it in a suitable manner into the cavity of the foam molding tool before the cavity is foamed up. By suitably choosing the suitably different materials for the closed and resistant outer skin as well as for the foaming material used for foaming, it is possible to meet the often contradictory requirements for a durable outer skin in conjunction with a soft area arranged underneath.

The separate production of an outer skin is associated with an increased production cost. If integral foams are used, then the outer skin must be formed by it during the setting of the integral foam and then removed from the foaming mold. While this can be done successfully for a long time with small decorative moldings having a substantially smooth surface, the known manufacturing methods are not yet suitable for the production of larger decorative moldings, especially if the surface is not smooth.

Thus, for example, instrument panels have not been produced to an appreciable extent from an integral foam, as instrument panels have a relatively complex shape and the surface often shows a grain, which is intended to imitate, for example, the surface of natural leather. It has been found that such a large-area foam moldings often adhere to the foam mold even when using a release agent and can be removed regularly only with the use of large forces. In addition, any unforeseen contact of the outer skin of the integral foam molding with the often sharp-edged and abrasive grain on the inside of the foam mold leads to surface damage. Especially with decorative moldings for indoor Fairing of motor vehicles cause visible damage to the outer skin of the decorative molding that this can no longer be used and thus has become worthless.

Object of the present invention is therefore to provide a method for producing a foam molding in such a way that the foam molding is as easy to produce and can be removed easily from the Schäumformwerkzeug to reduce the risk of visible damage to the surface of the foam molding.

This object is achieved in that after curing of the foam material of the foam-filled cavity is pressurized before the foam molding is removed. Due to the closed-pore outer skin of the foam molding, pressurization in the foam-filled cavity leads to compression of the foam molding and thereby also causes detachment of the outer skin of the foam molding from the surrounding foam molding tool.

The pressurization can occur both when using integral foams and when using an outer skin produced in a preceding method step and arranged in the cavity, since the foam molding only needs to have a closed surface in order to be compressed when pressurized. It is irrelevant to the process whether this closed outer skin is formed during foaming or produced in a separate process step and subsequently joined to the foam material. It is also possible for further material layers to adhere to or be connected to the closed outer skin, such as, for example, color layers or lacquer layers which have been applied to the inside of the foam mold prior to foaming of the cavity and connect to the outer skin during foaming and setting of the foam material , Even if not all areas of the outer skin of the foam molding have completely detached from the Schäumformwerkzeug, the pressurization leads to a significant reduction in the contact pressure of the foamed in the cavity foam material to the Schäumformwerkzeug and thereby reduces the expended for a removal of the foam molding from the Schäumformwerkzeug Force . If sufficient pressure is applied, the foam molding is compressed so far that there is no engagement between its outer skin and the grain of the foam molding tool.

Irrespective of the use of an integral foam or a separately produced outer skin, pressurization of the foamed cavity facilitates removal of the foam molding from the foam molding tool, in particular with slight undercuts or very small demoulding angles. It is not necessary in all cases that the outer skin has already been completely detached from the Schäumformwerkzeug, as already by a partial detachment of the outer skin or reduction of the contact pressure of the foamed foam molding to the Schäumformwerkzeug complete removal and removal of the foam molding is facilitated.

Preferably, it is provided that before foaming a carrier is introduced into the Schäumformwerkzeug and the cavity formed by the carrier and the Schäumformwerkzeug is filled with foam and pressurized after curing of the foam material before the carrier with the foamed Schaumma- material is removed. Especially with larger decorative moldings for the inner lining of a motor vehicle, it is customary to connect a carrier made of a forming, stable material with a coating of foam whose visible outer side has a closed and resistant surface. For example, according to the invention, in the case of the known positioning method of such instrument panels facilitate the removal and removal of the arranged in the foaming mold carrier with the associated foam molding. In this way, even complex designed instrument panels can be produced using an integral foam, without the separate production of a einzulegenden into the Schäumformwerkzeug outer skin is required. In addition, instrument panels often have slight undercuts and low draft angles, so that removal of such foam moldings together with the carriers connected with them is facilitated, regardless of the foam material used.

Advantageously, it is provided that a gaseous or a liquid pressure medium is introduced for pressurizing into the cavity. In the simplest case, the pressure medium used could be air that is blown into the cavity at the edge of the foam molding between the support and the foam molding tool. By a suitable specification of the flow direction and the Einströmungsdrucks can be tried, a gap between the Schäumformwerkzeug and the adjacent outer skin of the

To produce foam moldings and to support the detachment of the foam molding of the Schäumformwerkzeug. Instead of compressed air, any other suitable gaseous or liquid pressure medium can be used. In addition to the mechanical properties of the pressure medium, such as its compressibility or creep, the abrasive or chemical properties should also be taken into account, so that no undesired impairment of the outer skin of the foam molding, for example by chemical reactions, etc., is to be feared.

According to an advantageous embodiment of the invention, it is provided that the pressurization is increased stepwise or continuously up to a predetermined maximum pressure. Especially with an initially still existing Engagement of the outer skin in the grain of the Schäumformwerkzeugs, it is advantageous to carry out a controlled increasing pressurization starting with a low initial pressurization. In this way, a sudden detachment of large areas of the outer skin is avoided, which could lead to an undesirable damage to the outer skin during the detachment process. Also, the pressurization can be adjusted and controlled depending on the shape of the foam molding to promote a uniform pressure distribution along the outer skin by a slow pressure build-up in complex shapes.

In order to counteract an unintentional displacement of the carrier in the foam mold, it is provided that a counterforce, which is coordinated with the pressurization of the cavity, is exerted on the carrier. Conventionally used holding devices, with which the carrier is held in known manner in the foaming mold and subsequently removed therefrom, are not readily adapted to withstand the forces generated by the additional pressurization. A displacement of the carrier is therefore counteracted by the additionally applied counterforce to preclude undesirable movement of the foam molding during pressurization and thereby caused gradual detachment of the outer skin of the foam mold and thereby reduce the risk of visible damage to the outer skin.

It is provided that the pressurization of the cavity actuates a cylinder-piston device or a membrane with which the counterforce is exerted on the carrier. In this way it could be ensured by simple means that the forces exerted on the carrier by the application of pressure can be compensated by an identical counterforce. Advantageously, it is provided that the cavities of two adjacently arranged Schäumformwerkzeugen be pressurized simultaneously and uniformly and the respective carriers are in operative connection with each other, so that in each case one carrier counteracts a displacement of the other carrier. Additional devices for controlling and exercising a force applied to the carrier counterforce are then not required.

An embodiment of the inventive concept will be explained in more detail below, which is shown in the drawing. It shows :

1 shows a foaming mold and a carrier arranged therein, which form a cavity into which a foam material used for foaming is already filled,

FIG. 2 shows the foaming mold shown in FIG. 1 after complete setting and hardening of the foam material, FIG.

Fig. 3 is an initial pressurization of the cavity in the

Schäumformwerkzeug,

Fig. 4 is a fully pressurized cavity in the

Foaming mold, and

Fig. 5, the removal of the carrier with the associated foam molding from the Schäumformwerkzeug.

With reference to the embodiment and application example described below and illustrated in the drawings, the invention is merely exemplified in more detail, ie it is not on this embodiment and application example or on the Feature combinations within this embodiment and application example limited. Process and device features result analogously also from device or process descriptions.

Individual features that are indicated and / or illustrated in connection with a specific embodiment, are not limited to this embodiment or the combination with the other features of this embodiment, but may in the context of the technically possible, with any other variants, even if they are in are not treated separately.

The same reference numerals in the individual figures and illustrations of the drawing designate the same or similar or the same or similar components. On the basis of the representations in the drawing, those features are also clear, which are not provided with reference numerals, regardless of whether such features are described below or not. On the other hand, features that are included in the present description but are not visible or illustrated in the drawing will be readily understood by those skilled in the art.

The implementation of the method according to the invention is clearly illustrated in FIGS. 1-5. A foaming mold 1 and a carrier 2 arranged therein form a cavity 3. The carrier 2 forms the basic shape for an instrument panel, which is to be coated to improve the look and the feel with a foam material. In the cavity 3 a foam material 4 is filled and foamed.

Fig. 2 shows a snapshot after the complete setting and hardening of the foam material 4 in the cavity 3. The foam material 4 used is an integral foam, which during the setting process at the contact surface to an inside of the 5 Foam mold train 1 hardens and forms a closed and resistant outer skin for a foam molding 6. The inner side 5 of the foaming mold 1 is provided with a grain which effects a surface finish of the outer skin of the foam molding 6 which is similar to a natural leather material.

If, instead of the integral foam, another foam material 4 were used, the separate production of a closed outer skin made of optionally different material could be required in an additional preceding method step. The closed outer skin would then have to be arranged on the inner side 5 of the foaming mold 1 before introducing and foaming the foam material 4 used.

Before removal from the mold and removal of the foam molding 6 connected to the support 2 from the foam molding tool 1, the entire assembly is brought into a pressure chamber, not shown. The cavity 3 containing the foam molding 6 is pressurized by introducing a suitable pressure medium. The pressurization causes increasing compression of the foam molding 6 in the cavity 3 and leads to a gradual detachment of the outer skin of the foam molding 6 from the inside 5 of the Schäumformwerkzeugs 1. Since this detachment movement of the foam molding 6 is substantially perpendicular to the surface of the inner side 5 of the Schäumformwerkzeugs 1 Visible damage to the outer skin of the foam molding 6 is almost impossible.

With a slowly increasing pressurization, initially edge regions of the foam molding 6 are released from the foam molding tool 1 (FIG. 3) until increasingly larger regions of the outer skin of the foam molding 6 are lifted off the foam molding tool 1 and finally a continuous gap between the outer skin of the foam molding 6 and the foaming mold 1 is formed (Figure 4). Suitable release agents on the inside Side 5 of the foaming mold 1 and binder on the outside of the carrier 2 ensures that the foam molding 6 preferably, or exclusively from the Schäumformwerkzeug 1 and not from the carrier 2 dissolves.

Once a sufficient gap between the outer skin of the foam molding 6 and the inside 5 of the Schäumformwerkzeugs 1 has been generated and thus a complete demolding of the foam molding 6 has taken place from the Schäumformwerkzeug 1, it can be started, the carrier 2 together with the associated foam molding 6 from the Foam mold 1 to remove, as shown in Figure 5. In order to prevent unwanted expansion of the foam molding 6 during the removal of the carrier 2 from the Schäumformwerkzeug 1 of the pressure generated during the removal of the carrier 2 is preferably maintained until its complete removal from the Schäumformwerkzeug 1.

The invention is illustrated by way of example only in the description and in the drawings and not limited thereto, but includes all variations, modifications, substitutions and combinations that the skilled person the present documents in particular in the context of the claims and the general representations in the introduction of this description and the description of the embodiment and its representations in the drawing and combined with his expert knowledge and the prior art in particular including the full content of the state of the art given in this description. In particular, all individual features can be combined within the scope of the technical possibilities and functions.

Claims

Patent claims

1. A process for producing a foam molding having a closed-pore outer skin in a foam molding tool, wherein a suitable foam material is introduced and foamed into a cavity formed in the foam molding tool, characterized in that after curing of the foam material (4) the foam-filled cavity (3 ) is pressurized before the foam molding (6) is removed.

2. The method according to claim 1, characterized in that before foaming a carrier (2) is introduced into the Schäumformwerkzeug (1) and the foam formed by the carrier (2) and the Schäumformwerkzeug (1) cavity (3) and after the Curing the foam material (4) is pressurized before the carrier (2) with the foamed foam material (4) is removed.

3. The method according to claim 1 or 2, characterized in that a gaseous pressure medium for pressurization in the cavity (3) is introduced.

4. The method according to claim 1 or 2, characterized in that a liquid pressure medium for pressurization in the cavity (3) is introduced.

5. The method according to any one of the preceding claims, characterized in that the pressurization is increased stepwise or continuously up to a predetermined maximum pressure.

6. The method according to any one of the preceding claims 2 to 5, characterized in that on the carrier (2) on the pressurization of the cavity (3) tuned counterforce is exercised.

7. The method according to claim 6, characterized in that by the pressurization of the cavity (3) a cylinder-piston device or a diaphragm is actuated, with which the counterforce on the carrier (2) is applied.

8. The method according to any one of the preceding claims 2 to 7, characterized in that the cavities (3) of two adjacently arranged Schäumformwerkzeugen (1) are simultaneously and uniformly pressurized and the respective carrier (2) are in operative connection with each other, so that in each case one (2) carrier counteracts a displacement of the other carrier (2).