Sandwich component and method for the production thereof

The method for the production of a sandwich component comprising a honeycomb core (1) with a plurality of webs (1′) and at least two cover layers (2, 3), the honeycomb core (1) consisting paper, cardboard or other cellulose-based material, wherein the cover layers (2, 3) are formed from a fiber-reinforced semi-finished material with a thermoplastic matrix, wherein the webs (1′) of the honeycomb core (1) are at least partially accommodated in the thermoplastic matrix of the cover layer (2, 3) at connecting points (A) to the cover layer (2, 3), thus providing a composite of the sandwich component, and wherein the sandwich component has an edge seal created by joining the cover layers (2, 3) by local melting of the thermoplastic matrix of the cover layers (2, 3), the sandwich component having a shape curved about a radius (r), the method comprising the steps of:

• wetting the honeycomb core (1) with water (5) or with a starch-dissolving solution by spraying or by means of vapour,
• placing the wetted honeycomb core (1) in a pressing tool with an upper die (4′) and a lower die (4) which provide the preset curved shape of the sandwich component,
• forming the wetted honeycomb core (1) in the pressing tool by applying a pressure at a temperature in a range of 40 to 200 degrees C.,
• providing at least two fiber-reinforced semi-finished materials with a thermoplastic matrix and placing the semi-finished materials above and/or below the honeycomb core (1),
• positioning of the assembly in the pressing tool,
• applying pressure and bonding the assembly consisting of the semi-finished materials and the honeycomb core (1), the thermoplastic matrix being subjected to a temperature between a glass transition temperature and a melting point of the plastic material,
• wherein the bond is provided by at least partially melting the thermoplastic matrix and a partial accommodation of the webs (1′) of the honeycomb core (1) in the thermoplastic matrix at connecting points (A) of the webs (1′) to the cover layer (2, 3) represented by the fiber-reinforced semi-finished material with the thermoplastic matrix, wherein the semi-finished materials provided for forming the cover layers have dimensions which overlap a surface of the honeycomb core and its edge surfaces, and in that under the application of pressure the projecting edges of the semi-finished materials are bent around the edge of the honeycomb core, and in that the bonding of the cover layers and a sealing of the honeycomb core are provided by a local melting of the thermoplastic matrix to bond the cover layers (2, 3) to each other and to the edge of the honeycomb core.

A method for making a load-bearing component or an interior trim element for a motor vehicle selected from a floor plate, a rear seat backrest, a roof lining, a seat component, a central door panel and a door leaf, wherein the component is a sandwich component comprising a honeycomb core (1) with a plurality of webs (1′) and at least two cover layers (2, 3), the honeycomb core (1) consisting of paper, cardboard or other cellulose-based material, wherein the cover layers (2, 3) are formed from a fiber-reinforced semi-finished material with a thermoplastic matrix, wherein the webs (1′) of the honeycomb core (1) are at least partially accommodated in the thermoplastic matrix of the cover layer (2, 3) at connecting points (A) to the cover layer (2, 3), thus providing a composite of the sandwich component, and wherein the sandwich component has an edge seal created by joining the cover layers (2, 3) by local melting of the thermoplastic matrix of the cover layers (2, 3), the sandwich component having a flat shape or a shape curved about a radius (R), the method comprising the steps of:

• providing the honeycomb core (1) having the edge (10) dimensions of the load-bearing component or an interior trim element to be produced, and at least first and second fiber-reinforced semi-finished materials with a thermoplastic matrix,
• placing the semi-finished materials of the cover layers (2, 3) above and below the honeycomb core, wherein the semi-finished materials overlap around the edge (10) of the honeycomb core (1),
• positioning the assembly in a pressing tool with an upper die (4′) and a lower die (4) which provide the preset flat or curved shape of the sandwich component, and with an upper folding device (6′) associated with the upper die (4′) and a lower folding device (6) associated with the lower die (4) for pressing and fusing the semi-finished materials of the cover layers (2, 3) around the edge of the sandwich component, wherein the stroke of the pressing tool is limited by lower folding device (6) as a stop for upper folding device (6′),
• applying pressure via the die and bonding the assembly consisting of the semi-finished materials and the honeycomb core (1), wherein the semi-finished materials are joined around the periphery of the core (1) and to the side of the core by the pressure of the upper and lower folding devices (6′, 6), the thermoplastic matrix being subjected to a temperature between a glass transition temperature and a melting point of the plastic material, wherein the bond is provided by at least partially melting the thermoplastic matrix and a partial accommodation of the webs (1′) of the honeycomb core (1) in the thermoplastic matrix at connecting points (A) of the webs (1′) to the cover layers (2, 3) represented by the fiber-reinforced semi-finished material with the thermoplastic matrix, wherein the semi-finished materials provided for forming the cover layers have dimensions which overlap a surface of the honeycomb core and its edge surfaces, and in that under the application of pressure the projecting edges of the semi-finished materials are bent around the edge of the honeycomb core, and in that the bonding of the cover layers and a sealing of the honeycomb core are provided by a local melting of the thermoplastic matrix, and
• installing the sandwich component as a load-bearing component or an interior trim element of a motor vehicle.