Method for producing a negative skin, and tool

Abstract

The present invention relates to a method for producing a negative skin and a tool. Such a tool can be used, for example, in the automotive industry.

Claims

1. A method for producing a negative skin, the method comprising acts of: providing a positive body, wherein a first surface of the positive body forms a positive mold of a negative skin to be produced, wherein the first surface comprises at least one undercut, applying a wax layer on the first surface of the positive body and filling the at least one undercut with the wax layer, placing a tool cavity on the positive body, coating the tool cavity on the applied wax layer with an applied layer, removing the wax layer to form a cavity for the negative skin, and producing the negative skin within the cavity, wherein the cavity is formed between the first surface of the positive body and the applied layer.

2. The method according to claim 1, wherein the positive body is held by a base body.

3. The method according to claim 2, wherein the base body is tempered.

4. The method according to claim 1, wherein the tool cavity is tempered.

5. The method according to claim 1, wherein the wax layer has, in areas where no undercuts are filled in, a thickness of 1 mm to 2 mm.

6. The method according to claim 5, wherein the wax layer has, in areas where no undercuts are filled in, a thickness of about 1.5 mm.

7. The method according to claim 1, wherein the layer of the tool cavity has a thickness of 5 mm to 15 mm.

8. The method according to claim 7, wherein the layer of the tool cavity has a thickness of 5 mm to 12 mm.

9. The method according to claim 7, wherein the layer of the tool cavity has a thickness of about 9 mm.

10. The method according to claim 1, wherein the first surface of the positive body is a grained surface, including an etched grain or a laser grain.

11. The method according to claim 1, wherein the negative skin is a silicone skin.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic cross-sectional view of a first method step according to the present embodiment;

(2) FIG. 2 shows a schematic cross-sectional view of a second method step according to the present embodiment;

(3) FIG. 3 shows a schematic cross-sectional view of a third method step according to the present embodiment;

(4) FIG. 4 shows a further process with the used tool cavity;

(5) FIG. 5 shows a cast skin produced by a cast skin tool according to the present embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) A preferred embodiment of the present invention is described below by the enclosed figures. Further modifications of certain individual features mentioned in this context can each be combined with one another in order to form new embodiments.

(7) The present embodiment relates to a method for producing a negative skin. Negative skins 16 can be produced by such a method. In the context of the following description, the term negative skin refers to the thus produced intermediate product which, as shown above, can be used in a subsequent method, for example for producing surfaces by coating application as part of a foaming method or for producing, for example, PU skins.

(8) Such negative skins 16 can have variable thicknesses, curvatures and dimensions and are used, for example, in the automotive industry, for example in the production of dashboards. Further examples are door panels, glove box covers, steering wheels or the like. To create an improved haptic feel, a PU skin produced with this negative skin 16 can be coated and foamed before mounting. However, the negative skins produced within the scope of the present invention are primarily used—by application of a coating on the negative skin and subsequent foaming—to obtain a component having a corresponding coated surface.

(9) Negative skins 16 are preferably made of silicone compounds. However, the following embodiment is not limited to this.

(10) FIG. 1 shows a schematic cross-section of a first method step according to the present embodiment. A Galvanoform mold 11 forms a positive body having a surface corresponding to a positive surface of a skin to be produced in a further method. The positive surface of the Galvanoform mold 11 has textures which should also characterize the later negative skin 16, for example a leather grain or structures for a better haptic experience, impregnated trade names or safety instructions. In the present embodiment, the Galvanoform mold 11 has a thickness in the range of 3 mm to 5 mm, preferably about 4 mm.

(11) This Galvanoform mold 11 is mounted on a solid base body 12, wherein the positive surface of the Galvanoform mold points away from the base body. The base body 12 can be tempered. This can be realized by liquid cooling through the base body 12 or by single heating or cooling elements being provided at different points of the base body 12. Preferably, the temperature of the base body 12 can be controlled so as to precisely achieve a desired cooling curve of a used material for the negative skin 16. More preferably, this control can also be configured in an adaptive manner so as to better adjust to high temperature gradients. The tempering of the base body 12 and the temperature control thereof is not shown in FIGS. 1 to 5.

(12) In the first method step of the preferred embodiment, the Galvanoform mold 11 is mounted on the base body 12.

(13) FIG. 2 shows a next subsequent step. Here, a wax layer 13 is applied on the Galvanoform mold 11. The thickness of the wax layer 13 essentially corresponds to the thickness of the later negative skin 16. This thickness can preferably be in a range of between 1 mm and 2 mm, for instance about 1.5 mm, which has proven to be a good value for negative skins 16 of silicone in the automobile industry. Other applications or used materials can require other thicknesses.

(14) In addition, the provided undercuts are also filled in this wax application step. This can be done after an even wax layer 13 was applied as described above or at the same time thereas. The wax layer 13 thus obtained essentially has the same geometry as a negative skin 16 to be later produced by the tool.

(15) FIG. 3 shows a following step. Firstly, a tool cavity 14 is moved towards the previously created combination of Galvanoform mold 11, base body 12 and wax layer 13. The tool cavity 4 does not have any undercuts.

(16) Preferably, the tool cavity 14 can, just as the base body 12, be tempered and, more preferably, the temperature thereof can be controlled.

(17) After the tool cavity 14 is moved, there is a gap between a surface of the tool cavity 14, which is opposite the negative surface of the base body 12, and the surface of the previously produced wax surface. This gap is coated in this third method step using a layer 15.

(18) This layer 15, which is restricted by the two surfaces defined above, preferably has a thickness of about 9 mm. Irregularities of the geometry of the tool cavity can be corrected by changing the thickness of the layer 15. However, it is preferred that the thickness of the layer 15 does not vary too much so as to avoid an uneven temperature gradient.

(19) Thus, a surface of the layer 15 is connected to the one surface of the wax layer 13. Since, as described above, this one surface of the wax layer 13 is a positive surface of the negative skin 16 to be produced, the surface of the layer 15 is thus a negative surface thereof.

(20) The tool for producing a negative skin 16 produced according to these steps thus geometrically defines the negative skin 16 by a surface of the Galvanoform mold 11 and a surface of the layer 15 of the tool cavity 14.

(21) Before using the tool, its wax layer of the Galvanoform mold 11 can still be removed.

(22) FIG. 4 shows a resulting tool cavity 14 with applied layer 15. Since it is free of undercuts, this tool cavity 14 can be used in further processes as a supporting mold for the negative skin 16.

(23) A tool produced by this method is now able to produce negative skins 16, such as shown, for example, in FIG. 5. These negative skins 16 have thickenings on a surface thereof so as to allow a tool free of undercuts or a tool having fewer undercuts.

LIST OF REFERENCE NUMBERS

(24) 11 Galvanoform mold (positive body)

(25) 12 base body

(26) 13 wax layer

(27) 14 tool cavity

(28) 15 layer

(29) 16 negative skin