WO2007071207A2

WO2007071207A2 - Mask for manufacturing of multicolour elastomer skins

Info

Publication number: WO2007071207A2
Application number: PCT/CZ2006/000092
Authority: WO
Inventors: Jarosiav Kozak; Rupert Hune; Jürgen BÄUMKER
Original assignee: Cadence Innovation K.S.
Priority date: 2005-12-22
Filing date: 2006-12-20
Publication date: 2007-06-28
Also published as: EP1968776A2; WO2007071207A3

Abstract

A mask for manufacturing of multicolour elastomer skins by distributing of powdered thermoplastics onto the surface of a preheated metallic mould. The mask does contain a body (1) of the mask which is along its perimeter being in contact with the surface of the mould (2) equipped with a perimeter groove (11), in which an elastic sealing (3) is deposited. Furthermore, the body (1) of the mask is equipped with an inlet transfer canal (4) for supply of pressure air into the space under the body (1) of the mask and eventually with at least one flow canal (7) enabling flowing through of a tempering medium as well as with a vacuum transfer canal (5) for creating of vacuum in the space under the body (1) of the mask.

Description

Mask for raanufacturiπg of multicolour elastomer skins

Field of the Invention

The invention relates to a mask for manufacturing of multicolour elastomer skins by the way of spraying of .a powdered thermoplastics onto the surface of a preheated metallic mould where the powder is be melted down and sintered in the way to create a thin layer of an artificial skin intended for interiors of motor vehicles .

Background of the Invention

The elastomer skins do create parts of interiors of motor vehicles. These skins are used for facing (lining) of external surfaces of the inner body panels, for instance facing of instrument panels, door panels, etc. The skins are mostly manufactured from thermoplastic elastomers by distributing of them onto a negative metallic mould equipped with a negative surface structure. The shape of this mould corresponds exactly with the product to be covered with the manufactured skin. Thus the products covered with such skin may have even a very complex shapes .

Hitherto, the methods used for manufacturing of elastomer skins are based on four different ways of application of the elastomer:

1. By strewing of the powdered thermoplastics onto the surface of a pre≡heated metallic mould where the powder is melted down and sintered in the way to create a thin layer called artificial skin. 2. By spraying of a powdered thermoplastics onto the surface of a preheated metallic mould where it is melted down and sintered in the way to create a thin layer called artificial skin.

3. By immersing of the surface of a pre^heated metallic mould into a layer of powdered thermoplastic elastomer where the powder is melted down and sintered in the way to create a thin layer called skin.

4. By spraying of a liquid reaction mixture of components onto the surface of a pre-heated metallic mould where the reaction mixture becomes - via polymerisation process -elastomer (for instance polyurethane-based, see patent No. US6071619) and creates the elastomer layer called skin.

Mostly, the first two methods are implemented. In course of these methods, the mould - mostly made from a metal

- must be preheated in a reliable way_. over the melting interval of the powdered elastomer to be distributed. Thus

- in course of the manufacturing process - the temperature of the mould must change for interval of hundreds of degree centigrade. By masking of parts of the mold surface using single one or more masks - to prevent adhesion of the particles of powdered thermoplastics - the thermoplastic materials of different colours and/or properties may be distributed step by step onto different places of the mold in the way to create a skin which may provide different colours and/or properties on different parts of the mould.

If a mask being in direct contact with the mould surface to be masked is used, some troubles may appear. To achieve a good functionality of the mask, the mask must perfectly suit with the mould and it must provide a proof sealing ability along the whole perimeter in order to prevent contaminating of the covered mold surface by powdered thermoplastics of a non-correct colour.

If the dimensions of the mask and mould are larger, or if their shapes are more complex, it is very difficult to achieve the effects described above. The different temperature dilatation (elongation) of the mould and mask as well as changes of their shapes caused by the temperature changes in course of the skin manufacturing process do result in different changing of dimensions and shapes of the mould and mask. Thus the border of the mask may partially lose the direct contact with the mould and consequently the sealing effect is over. In addition the mask must provide an easy and quick extracting/deflecting from the mould whereby in course of the removal process no excessive powdered thermoplastics may penetrate into the space under the mask.

Furthermore, - in case of more complex product shape - the processes of applying and extracting of the mask are very difficult because part of the complex mold equipped with a deeper cavity and the determined colour dividing lines in the skin may - taking the limited space inside of the mould into account - hinder or even completely prevent the applying of the mask to the area to be covered. In such a case some change of position of the colour dividing lines within the mould or some easier mould shapes would be necessary however such changes would cause variations as to appearance and shape of the product . These changes may be unacceptable for the customer.

Thus the objective of the presented invention is to provide such constructive design of the mask which eliminates the application troubles described above. Summary of the Invention

^• The objective is achieved by the means σf the mask for manufacturing of multi-colour elastomer skins by distributing of powdered thermoplastics onto the surface of a preheated metallic mould according to the invention. The invention consists in a mask body which is along the perimeter being in a close contact with the functional surface of the mould equipped with a perimeter groove . An elastic sealing is placed in the groove. Furthermore, the body of the mask is equipped with a inlet transfer canal for supply of pressure air into the space under the body of the mask. Thus some air overpressure may be kept under the mask which aids the sealing effect and - in addition - the pressured air will blow away the excessive powdered thermoplastics in course of extracting/deflecting of the mask .

Furthermore, the invention consists in a sliding/moveable deposition of the elastic sealing in the perimeter groove whereas an elastic hose is deposited under the elastic sealing and filled with an inner media. Thus the elastic sealing may be drifted in a controlled way out of the perimeter groove against the mould surface in order to assure an overall constant sealing pressure even on places where the shape of the mask perimeter have been changed because of tension in the mask as well as because of changing of dimensions of mould and mask in consequence of temperature dilatations .

The temperature tension in the mask and the consequent dilation and change of the shape of the mask may be limited in a significant way by tempering of the mask which ^■; according to the invention ≤ may be in an advantageous way implemented by the means of single one or more flow canals enabling flowing through of a tempering medium in order to assure the required temperature of the mask as even as possible.

The basic sealing effect between the mask being applied and pressed (thrust) to the mold and the mould is assured by the elastic sealing deposited in the perimeter groove. Furthermore, the thrust may be - according to the invention - after applying of the mask in an advantageous way accelerated by exhausting of the air (vacuum effect) from the space under the mask via separate vacuum transfer canal. An elimination of this thrust may be achieved in a very rapid way by the means of inlet transfer canal supplied with pressure air. Some air overpressure in the space under the mask is s usually e achieved by the means of this inlet and transfer canal shortly prior to extracting (deflecting) of the mask.

Furthermore, the invention consists in a body of the mask equipped with at least one sliding/moveable element which leads along a part of the whole sealing line of the perimeter of the body of the mask. This sliding/moveable element may be moved between the position where its border is directly in contact with the functional surface of th© mould - in order to support the sealing effect along the perimeter of the mask - and the position which enables deflecting of the mask off the mould. In addition the sliding/moveable element is sealed to the mask too in order to prevent any penetrating of the distributed powdered thermoplastics into the space under the mask. Thus the mask does not consist of a single one piece of material but at least one part of the mask =^■ which would otherwise hinder the application of the mask to the area of the mould to be masked - slides/moves in a controlled way between two limit positions. In the one limit position th© space under the applied mask is sealed, and in th© other limit position the sliding element does not prevent nor hinder the applying of the mask on the area to be masked as well as deflecting of the mask, i. e. it prevents collision of the mask with the mould or with any- other adjacent equipment. The movement of the sliding part of the mask may be initiated by any suitable equipment

- purely in mechanic way, in pneumatic, in hydraulic or in electric way.

These measures assure - along the whole technology process of manufacturing of multicolour elastomer skins = a perfect sealing between the mask and the mould along the whole contact perimeter line. The invention eliminates the common practical implementation problems caused by insufficient mask sealing and by penetrating of the powdered material into the wrong parts of the mould. Thus the invention increases the quality of the manufactured multicolour elastomer skins in a significant way.

Furthermore, if the body of the mask is - additionally

- equipped with the sliding/moveable element, the manufacturing of the even most complex - as to colours as well as shapes - multicolour elastomer skins is enabled.

Brief Description of the Dravings

The invention is in detail described by drawings showing some examples of masks for manufacturing of elastomer skins, as follows:

Fig. l - schematic section through a mould with applied mask

Fig. 2 - section through a border of the body of the mask with perimeter groove as well as with an elastic sealing deposited in the groove Fig. 3 - section through a border of the body of the mask with a perimeter groove as well as with an elastic sealing moveable (sliding) deposited in the groove and with an elastic hose placed under the sealing

Fig. 4 - section through the applied mask equipped a sliding/moveable element

Fig. 5 - detail section through the mask from Fig. 4 in a position enabling application of the mask onto the mould

Fig. 6 - detail section through a part of the mask from Fig. 4 in contact with the mould

Description of the Prefered Embodiment

Example 1

The mask according to the first example of implementation of th@ invention as shown on Fig. 1, 2 and 3 is determined for the process of manufacturing of two-colour skin from a vinyl thermoplastic elastomer, a skin determined for facing of an instrument panel of a personal motor vehicle. The process is based on distributing of powdered thermoplastic elastomer onto a hot surface of the mould 2 , which is made from a nickel alloy, where the powder is melted down and sintered in the way to create a continuous layer. A part of the surface of the mould 2 is covered with the mask, i. e. where the elastomer of the first colour shall not be applied. After it the functional surface of the mould 2 shall be sprayed with powdered elastomer of the first colour. After sintering of this first layer the mask shall be extracted and the mould 2_. shall be covered with a cover containing a filling of powdered thermoplastic elastomer of an other (second) colour. Through a repeated overturning of such vessel the powdered thermoplastic elastomer is applied to the rest hot functional surface of the mould 2. and the sintering of the powder takes place.

The mask contains the body 1 of the mask made from an aluminium alloy. As shown on Fig. 1, the borders of the body 1 of the mask are shaped according to the shape of the mould 2. following the line of connection each other, whereby the whole perimeter of the body 1 of the mask is equipped with an elastic sealing 3. because the mask must provide a reliable sealing effect towards the mould 2. along its whole perimeter.

Furthermore, the body 1 of the mask is equipped with an inlet transfer canal 4. providing supply of pressure air into the space under the body 1 at the mask as well as with a vacuum transfer canal 5. enabling low pressure (vacuum) in the space under the body 1 of the mask.

Thus it is possible (possibility No. 1) to keep permanently some air overpressure - by the means of inlet transfer canal 4. - and thus support the sealing of the space under the mask. Furthermore, the excessive powdered elastomer deposited along the perimeter of the mask will be blown away in course of extracting / deflecting of the mask. This is a reliable way how to prevent the powdered elastomer of non-correct colour from penetrating onto the masked surface of the mould 2.

Furthermore, it is possible (possibility No. 2) to support the thrust of the mask towards the mould - after application of the mask onto the mould 2 - by the means of vacuum (low pressure) in the space under the mask via a vaβϋum E-fangfiea? eaϊϊal 5.. The elimination 6£ t≥is Eheuse before extracting / deflecting of the mask or the elimination of an air overpressure under the mask - in order to blow away the surplus powdered elastomer - may be quickly achieved via supply of the pressure air through the inlet transfer canal 4..

The mask is tempered by water during the whole manufacturing process. Temperature of this water may be adjusted by a special external equipment. The water flows through a flow canal 1_ placed over the surface of the body 1 of the mask in ord@r to achieve the most possible even temperature of the mask after applying of the mask onto the mould 2. Thus the dilatation and changes of the borders of the mask towards the mould 2. are limited to a minimum.

As shown on Fig. 2 the borders of the body l of the mask are massive along the whole perimeter to provide sufficient rigidity as well as enough space for perimeter groove 3JL as well as for deposition of an elastic sealing 3. with four edges, the protuberant edges are filled out. The elastic sealing 3. is made from silicon rubber. Thus it is capable to master the working temperatures of the mould

2. as well as those of the mask without any damage.

In terms of increasing of the sealing effect, the sealing

3. is in a more advantageous implementation - as shown on Fig. 3 = deposited in a perimeter groove 11 in a sliding/moveable way, and an elastic hose J. is deposited on the bottom of the perimeter groove 3JL just under the elastic sealing J_. Both ends of the hose are on a place out of the mask perimeter connected to a pressure air supply. The controlled air pressure of about 1 bar is enough to move the sealing 3. even for about 1 ram out of the perimeter groove H and thus to reach a reliable sealing effect along the whole length of the contact of the mask with the mould 2.- Before deflecting of the mask from the mould 2. it is possible to eliminate the overpressure inside the elastic hose 6.. To provide resistance against high temperatures the hose J. is also made from silicon rubber.

Example 2

Th© mask according to the second example of implementation as shown on Fig. 4, § and β is also determined for manufacturing of two-colour skins made of vinyl thermoplastic elastomer for facing of the external surface of the instrument panel of a personal motor vehicle. In contrast to the example 1 this elastomer skin is more complex as to shape and colour layout.

As shown on Fig. 4, the cavity of the mould 2 is on the place of the head of the instrument panel very narrow. The shape of the mould 2 in this area as well as the placing of the dividing line between the two skin colours following the graphic design of the facing of the instrument panel do not allow applying of a one≤piece mask because such mask would be in collision with the mould 2. Therefore a part of the body 1 of the mask is cut away and this cut part is replaced by a sliding/mσveable element 8.. As shown on Fig. 4, the body 1 of the mask with its borders shaped according to the shape of the mould 2 along the line of mutual contact along the whole perimeter including of the sliding/moveable element 8. are equipped with an elastic sealing 3_. made from silicon rubber. As shown on Fig. 5, the sliding/mσveable element §. is on the body 1 of the mask sealed with additional sealing 10. and this sliding/moveable element 8_. is = by the means of a pneumatic moving mechanism 9. - moved away from the edge § of the mask to a position, where no part of the mould 2. do hinder the applying of the mould 2,.

After applying of the mask onto the mould 2. the sliding/moveable element 8. - initiated by a moving mechanism j? - moves to the edge of the mask in to its 0 second limit position, where the sliding/moveable element £ fulfils without any rest th@ part of the perimeter cut away in order to seal the space under the mask as shown on Fig. 6. After it the powdered thermoplastic elastomer of the first colour may be sprayed onto the functional 5 surface of the mould 2_.. After sintering of this first skin layer the sliding/moveable element § of the mask moves back from the edge of the body 1 of the mask and after it the mask is deflected from the mould 2 without collision with any part Qf tϊie mould 2.,

0 Afeer ±E EHe whale ffiQld 2 3HaIl BS esverefi - like in EMe example 1 - with a cover filled with a filling of powdered elastomer of the second (another) colour. By repeated turning over of th© closed vessel the hot functional surface of the mould 2 is sprayed with powdered S thermoplastic elastomer and sintered in order to create the second layer of the artificial skin. After cooling down of the mould 2 the finished two≡colour skin may be extracted from the mould 2.

Field of the Application

The invention may be used for manufacturing of interior 0 panels of the body of motor vehicles.

Claims

P A T E Sf T C L A I M S

1. A mask for manufacturing of multicolour elastomer skins by distributing of powdered thermoplastics onto the surface of a preheated metallic mould characterised by the fact, that a body (1) of the mask, which is along its perimeter being in contact with the surface of the mould (2) equipped with a perimeter groove (11) , in which an elastic sealing (3) is deposited whereas the body (1) of the mask is equipped with an inlet transfer canal (4) providing a supply of pressure air into the space under the body (1) of the mask.

2. A mask according to the claim 1 characterised by the fact, that an elastic sealing (3) is deposited in the perimeter groove (11) in a moveable way and an elastic hose (€) is deposited in the perimeter groove (11) under the elastic sealing (3) , whereas the overpressure of the medium inside the elastic hose (6) may be changed und thus the volume of th© elastic hose (6) may be increased or decreased and thus the position of the elastic sealing (3) within the perimeter groove (11) may be adjusted.

3. A mask according to at least one of the previous claims characterised by the fact, that the body (1) of the mask is equipped with at least one flow canal (7) enabling flowing through of a tempering medium.

4. A mask according to at least one of the previous claims characterised by the fact, that the body (1) of the mask is equipped with a vacuum transfer canal (S) enabling vacuum under the body (1) of the mask.

5. A mask according to at least one of the previous claims characterised by the fact, that the body (1) of the mask is equipped with at least one sliding/moveable element (8) containing a part of the whole sealed perimeter of the body (1) of the mask whereas this sliding/moveable element (8) is moveable between a position, where its edge is in direct contact with the functional surface of the mould (2) and hereby the sealing perimeter of the body (1) of the mask is completed, and another position, which enables applying of the body (1) of the mask onto the mould (2) as well as deflecting of th@ mask.