The present invention relates to an opening part for an automotive vehicle of the type comprising an inner part and at least one outer part, said inner part and said outer part being attached together in at least one fastening area to form the opening part, said inner part being made at least partially of plastic material.

The invention also relates to a method for producing such an opening part and for producing an automotive vehicle body comprising such an opening part.

The invention for example applies to the rear opening part, or tailgate or trunk lid, of an automotive vehicle.

By opening part, it is meant a closure part that is movable relative to the body of an automotive vehicle between an opened position, wherein an opening granting an access to an inner volume of the body is accessible, and a closed position, wherein the opening is closed by the opening part.

It is known to produce such a part by assembling an inner part, arranged to be visible from the inside of the vehicle, and an outer part, forming the external surface of the opening part. The inner part is arranged to carry or form functional elements of the vehicle, such as, for example, means for opening the opening part, lights, a locking device, etc.

It is known to produce both the inner part and the outer part in a metal material, which provides an opening part having satisfactory mechanical properties and an outer appearance which is the same as the rest of the vehicle body, which is also made in a metal material. However, such an opening part made of metal adds a significant weight to the automotive vehicle. Furthermore, a trim element covering the inner part is generally required to confer a satisfactory appearance to the inner side of the opening part and numerous attaching elements have to be added for functional elements to be attached to the inner part.

It is also known to produce both the inner part and the outer part in a plastic material, which provides a light weight opening part. In this case, the inner part can directly be shaped, for example via injection molding, to have a satisfactory appearance on its inner side and to include attachment elements, for example clips or hooks, for the functional elements. Consequently, the assembly of the opening part is simplified. However, such an opening part can be less satisfactory in terms of mechanical properties and in terms of appearance. Indeed, the outer part is less easy to paint and does not have exactly the same appearance as the rest of the automotive vehicle body. In order to improve such an opening part, it is known to provide an inner part made of plastic material and comprising one or several metallic reinforcement elements. Such an opening part is known as a hybrid opening part. The reinforcement elements improve the mechanical properties of the opening part, while not adding a significant weight to the opening part. However, the problem of the outer appearance of the opening part remains. More particularly, the opening part cannot be painted on the same painting line as the automotive vehicle body because the painting processes are different and obtaining an opening part having the same appearance as the automotive vehicle body is difficult. Furthermore, the painting process requires particular care in the case of plastic material because a painting layer can be deposited on the inner side of the opening part during the painting process which is detrimental to the appearance of the inner side of the opening part.

Consequently, the painting of the opening part increases the costs of the opening part.

Furthermore, when such an opening part is damaged, for example in case of an impact, the whole opening part has to be replaced, which adds a significant cost when repairing the automotive vehicle.

One of the aims of the invention is to overcome the above-mentioned problems by providing an opening part having both satisfactory mechanical properties and appearance on the inner side as well as on the outer side and being easily repaired.

To this end, the invention relates to an opening part of the above-mentioned type, wherein the outer part is exclusively made of metal, the plastic material of the inner part being applied against the metallic material of the outer part in the fastening area and being attached to said metallic material in a non-continuous manner over the surface of the fastening area.

Having an outer part made exclusively of metal allows improving the mechanical properties of the opening part and confer to the opening part an appearance which can be exactly the same as the rest of the automotive vehicle body. More particularly, the outer part can be painted in the same manner as the rest of the automotive vehicle body on the same painting line. Consequently, the costs of the opening part can be reduced and the method of production of the automotive vehicle body can be simplified, as will be explained subsequently. Furthermore, if the outer part is damaged, only said outer part can be replaced and the whole opening part does not need to be replaced.

According to other advantageous aspects of the invention, the opening part comprises one or more of the following features, considered alone or according to any technically possible combination: - the inner part is glued to the outer part in the fastening area;

- at least one fastening element attaches the inner part to the outer part in the fastening area;

- the fastening area extends along at least a part of the periphery of the inner part and of the outer part;

- the inner part and the outer part are crimped together in the fastening area;

- the metal of the outer part is steel;

- the steel is a bake hardening steel and/or a dual-phase steel;

- the outer part is coated by a zinc-based coating;

- the inner part comprises an inner face and an outer face, said outer face facing the outer part, the outer face being shaped to comprise at least one functional element of the automotive vehicle;

- the outer part comprises a lower outer part and an upper outer part, each attached to the inner part in at least one fastening area, the lower and upper outer parts being made exclusively of metal; and

- the opening part is a rear opening part, such as a trunk lid or a tailgate.

The invention also relates to a method for producing an opening part as described above, the method comprising the steps of:

- providing at least one outer part made exclusively of metal,

- providing an inner part made at least partially of plastic material,

- attaching the inner part to the outer part in at least one fastening area, wherein the outer part is painted before being attached to the inner part.

By painting the outer part before attaching the outer part and the inner part together, there is no risk of depositing a paint layer on the inner side of the opening part.

According to another feature of the method, the outer part is subjected to a electrophoretic coating before being painted.

The invention also relates to a method for producing an automotive vehicle body, the method comprising the steps of:

- providing an automotive vehicle body part made of metallic material,

- providing at least one outer part of the opening part,

- subjecting the vehicle body part and the outer part to a painting process on a same painting line of a vehicle body producing line, wherein the inner part of the opening part is attached to the outer part after said outer part has been subjected to the painting process.

Consequently, with the method according to the invention, the outer part can be painted together with the automotive vehicle body part before being attached to the inner part. This greatly simplifies the painting process of the automotive vehicle body and reduces the costs of this process while guarantying an uniform appearance of the outer side of the automotive vehicle body.

Other aspects and advantages of the invention will appear upon reading the following description, given by way of example and made in reference to the appended drawings, wherein:

- Fig. 1 is a perspective exploded view of an opening part according to a first embodiment of the invention,

- Fig. 2 is a cross-section view of the opening part according to the invention, - Fig. 3 is a perspective exploded view of an opening part according to a second embodiment of the invention, and

- Fig. 4 is a perspective view of an automotive vehicle body during a painting process.

In reference to Figs. 1 and 2, an opening part 1 , or closure part, for an automotive vehicle is described. The represented opening part 1 is a rear opening part, such as a tailgate or trunk lid, arranged to close the rear access to the automotive vehicle and to the storage space generally found at the rear of the vehicle. It should be understood however that the invention could be applied to other opening parts of the vehicle, such as the side doors or the hood of the vehicle. More generally, the invention can be applied to any exterior closure part of the vehicle, arranged to close an opening of the vehicle when in the closed position. By closing, it is meant that the opening part, or closure part, extends over the opening such that said opening is not accessible.

The opening part 1 comprises an inner part 2 and an outer part 4 assembled together to form the opening part 1 .

The inner part 2 is intended to extend on the inner side of the automotive vehicle, meaning that the inner part 2 is intended to face the interior of the automotive vehicle and to be visible from said interior when the opening part 1 is in a closed position.

The inner part 2 is made at least partially of plastic material such as a thermoplastic material or a thermosetting material. According to an embodiment, the inner part 2 is exclusively made of plastic material. According to such an embodiment, the inner part 2 can easily be obtained by injection molding an integral inner part 2, i.e. an inner part made in a single piece. According to a variant, the inner part 2 can be made of several parts assembled together. According to another embodiment, the inner part 2 can comprise one or more reinforcement elements, for example made of a metallic material, the plastic material being overmolded on said reinforcement element(s). Such an inner part 2 has improved mechanical properties. The inner part 2 comprises an inner face 6 intended to extend in the interior of the automotive vehicle, and an outer face 8 facing the exterior of the vehicle.

The inner face 6 can be shaped to have a satisfactory appearance for the users of the vehicle, meaning that the inner face 6 can be left visible from the interior of the vehicle and does not require that a trim element is added on the inner face 6 of the inner part 2 to present the wanted appearance. The inner face 6 can also be shaped to comprise functional elements such as attachment elements for attaching additional elements on the inner face 6 of the inner part 2.

The outer face 8 is arranged to comprise to comprise at least one functional element of the automotive vehicle. Such a functional element is for example an attachment element for attaching an additional part on the opening part 2, for example a rear light or a window pane arranged to extend in an aperture 10 of the opening part 2. The functional element can also be a reinforcing rib or a network of reinforcing ribs for improving the mechanical properties of the inner part 2. The functional element can also be abutment elements protruding from the outer face 8 for abutting against the outer part 4 to locally reinforce said outer part 4 or to attach the outer part 4 to the inner part 4 as will be described subsequently. Other examples of functional elements comprise electric cable guides, locking means, supports for additional parts, etc. Several functional elements of different kinds can be provided on the outer face 8 of the inner part.

It should be noted that the shape of the inner face 6 and the functional elements on the outer face 8 can easily be integrated on the inner part 2 by molding, i.e. by arranging the shape of a molding cavity such that the plastic material flowing in the molding cavity acquires the shape of the inner face 6 and of the functional elements provided on the outer face 8. Consequently, the structure of the inner part 2 can easily be adapted to various requirements simply by modifying the shape of the molding cavity.

The outer part 4 is made exclusively of metal, meaning that the outer part 4 is not formed of any material other than metal. The metal is for example steel. Such an outer part 4 can be referred to as a skin.

According to various embodiments, the steel of the outer part 4 is a bake hardening steel having a yield strength for example comprised between 180 MPa and 300 Mpa. Bake hardening is a controlled aging phenomenon related to the presence of carbon and/or nitrogen in solid solution in the steel.

According to other embodiments, the steel of the outer part 4 is a high-strength steel having a ferrite and martensitic microstructure, also known as a dual-phase steel. The dual-phase steel has for example a yield strength comprised between 300 MPa and 380 MPa. It should be noted that the dual-phase steel can also be subjected to a bake hardening.

Other metal could be used to form the outer part 4, such as another kind of steel or aluminum. According to the embodiment shown in Fig. 1 , the outer part 4 is made of a single metal sheet, for example stamped into the wanted shape.

The thickness of the outer part 4 can be constant or variable and is for example comprised between 0.5 mm and 1 ,5 mm.

The outer part 4 comprises an inner face 10, extending opposite the outer face 8 of the inner part 2, and an outer face 12, turned towards the exterior of the vehicle. More particularly, the outer face 12 forms the external surface of the opening part 1 , meaning that the outer face 12 is visible from outside the automotive vehicle.

The outer face 12 has a shape adapted to have a satisfactory appearance, this shape being the final shape of the external surface of the opening part 1 , meaning that this shape will not be modified after the stamping of the outer face 12.

The outer part 4 is also adapted to the shape of the inner part 2 such that the contour of the inner part 2 and the outer part 4 are substantially the same and can be applied against each other. In other words, the outer part 4 is adapted to cover the inner part 2. When the inner part 2 comprises an aperture 10 as shown in Fig. 1 , the outer part 4 also comprises an aperture 14 arranged to face the aperture 10 of the inner part 2. These apertures 10 and 14 are for example arranged to receive a rear window pane.

The outer part 4 can also comprise additional apertures arranged to give access to functional elements provided on the outer face 8 of the inner part 2. For example, these functional elements can be dimensioned to protrude from the outer face 8 of the inner part 2 and to extend in the corresponding aperture provided in the outer part 4. Such a functional element extending through an aperture of the outer part 4 can for example be a support for a wiper of the window pane or a locking element of the opening part 1 in the closed position. The outer part 4 can also be contoured to allow the positioning of additional elements, such as rear lights, etc. supported by the inner part 2.

The roughness of the material of the outer part 4 can be adapted to allow a good adherence with the plastic material of the inner part 2, as will be described below. For example, the average depth of the surface profile (Ra) of the outer part is comprised between 0;5 μηι and 3 μηι. Meaning that the surface of the outer part 4, and more particularly of the inner face 8 of the outer part 4 can comprise microscopic recesses having a depth comprised between 0;5 μηι and 3 μηι.

The outer part 4 can also be galvanized by applying a coating to the metallic material of the outer part 4. Such a coating, in addition to improving the corrosion protection of the outer part 4, can also improve the adherence of the outer part 4 to the inner part 2, for example when the outer part 4 and the inner part 2 are glued together as will be described below. The coating is for example zinc-based coating comprising zinc, magnesium (around 3%) and aluminum (around 3.7%).

The inner part 2 and the outer part 4 are attached together in at least one fastening area 16, wherein the plastic material of the inner part 2 is applied against the metallic material of the outer part 4. More particularly, the outer face 8 of the inner part 2 is applied against the inner face 10 of the outer part 4 in the fastening area 16. In the fastening area 16, the inner part 2 and the outer part 4 are fastened together in a non-continuous manner over the surface of the fastening area, meaning that not all the plastic material and the metallic material in contact with each other in the fastening area 16 are bounded together. Accordingly, the metallic material of the outer part 4 is applied against the plastic material of the inner part 4 over the surface of the fastening area and, in this surface, a part of the metallic material is attached to a part of the plastic material while the reminder of the metallic material is not attached to the reminder of the plastic material in this surface. In another word, the inner part 2 and the outer part 4 are not welded together.

According to an embodiment, the plastic material of the inner part 2 and the metallic material of the outer part 4 are glued together in at least a part of the fastening are 16. The glue can for example bea bicomponent metacrylate adhesive, which can be used to glue the outer part 4 to the inner part 2 by induction without requiring a heating of the adhesive.

Alternatively, the glue can be a hot-melt adhesive. Such a hot melt adhesive can be advantageous in that by heating the adhesive, the outer part 4 and the inner part 2 can be separated such that the outer part 4 can be removed, for example for repairing or replacing the outer part 4. The heating of adhesive can be obtained by induction thanks to the magnetic properties of the outer part 4. Consequently, when the opening part 1 needs to be repaired, for example after an impact, the outer part 4 can simply be replaced by a new outer part 4 that can be attached to the same inner part 2. The costs of this repairing are therefore reduced compared to conventional opening parts.

Alternatively or additionally, at least one fastening element is arranged to attach the inner part 2 and the outer part 4 together in the fastening area 16. Such a fastening element can for example be a screw or a clip provided on the outer face 8 of the inner part 2 cooperating with an aperture in the outer part 4.

According to the embodiment shown in Fig. 2, at least one fastening area 16 extends at the periphery of the inner part 2 and of the outer part 4. In this case, at least a part of the edge of the outer face 8 of the inner part 2 is applied against at least a part of the edge of the inner face 10 of the outer part 4. According to a particular embodiment, the fastening area 16 extends on the whole periphery of the inner and outer parts 2 and 4 and the inner and outer parts 2 and 4 are attached together at intervals on said periphery for example by various glue patches and/or several fastening elements.

According to a particular embodiment shown in Fig. 2, which can be combined with the above embodiments, at least a part of the edge 18 of the outer part 2 is folded on part of the edge 20 of the inner part.

According to an embodiment shown in Fig. 2, several different fastening areas 16 are provided. For example, at least one fastening area 16 extends at the periphery of the inner and outer parts 2 and 4 and at least one fastening area 16 extends in a central area of the inner and outer parts 2 and 4, i.e. in an area spaced from the edges of the inner and outer parts 2 and 4. This can be obtained by forming a protruding area 21 on the outer face 8 of the inner part 2 such that said protruding area is applied against the inner face 10 of the outer part 4 and by attaching, for example by gluing or with a fastening element, this protruding area to the inner face of the outer part 4.

According to another embodiment, at least a part of the periphery of the outer part 4 could be crimped on at least a part of the periphery of the inner part 2.

According to the embodiment shown in Fig. 3, the outer part 4 comprises a lower outer part 26 and an upper outer part 28, each made exclusively of metal. In this case, the lower outer part 26 and the upper outer part 28 are each made from a metal sheet. The lower outer part 26 and the upper outer part 28 are then possibly attached together or they can be separately attached to the inner part 2 in at least one fastening area between the lower outer part 26 and the inner part 2 and in at least one fastening area between the upper outer part 28 and the inner part 2. In any case, the lower outer part 26 and the upper outer part 28 are each painted before being attached to the inner part 2.

Having an outer part 4 made exclusively of metal and attached to the inner part 2 without welding is advantageous in that the outer face 12 of the outer part 4 can have an appearance which is the same as the appearance of the rest of the vehicle body without deteriorating the appearance of the inner face 6 of the inner part 2, as will now be explained.

Having an outer part 4 made exclusively of metal allows painting the outer face 12 in the same manner as the rest of the vehicle body, meaning by using the same paint and by obtaining the same appearance since the paint is applied on similar materials, the rest of the vehicle body being also made of metal. Obtaining a similar result with a plastic material is very difficult because the aspect of the paint can change when it is applied to plastic. Consequently, to obtain the same color, the paint used for the vehicle body is different than the paint used to paint an external surface of a plastic part. Furthermore, the process is also different, making paint adhere to a plastic surface being harder than making the paint adhere to a metallic surface.

Furthermore, the outer part 4 can be painted before being assembled with the inner part 2, which is advantageous because the paint cloud created during this step of painting is not deposited on the inner part 2 and the step of painting is therefore not detrimental to the appearance of the inner part 2.

Consequently, the method of producing the opening part 1 comprises the following steps:

- producing the inner part 2, for example by injection molding,

- producing the outer part 4; for example by stamping a metal sheet,

- painting the outer part 4,

- attaching the inner part 2 to the outer part 4 by fastening the outer face 8 of the inner part 2 to the inner face 10 of the outer part 4 in the fastening area(s) 16, this step occurring after the step of painting the outer part 4.

The painting of the outer part 4 is for example preceded by a step of electrophoretic coating of the outer face 12 in order to improve the adherence of the paint on the outer face 12 during the painting step.

In a particularly advantageous embodiment, the painting of the outer part 4 is performed on the same painting line used to paint the rest of the automotive vehicle body. Since the outer part 4 is made exclusively of metal, there is no need to provide a separate painting station for painting the outer part 4, as it is the case when the outer part 4 comprises a plastic material. Consequently, the painting step is simplified and less costly.

According to the embodiment shown in Fig. 4, the outer part 4, here depicted with a lower outer part 26 and a upper outer part 28, without the inner part 2, is mounted on a vehicle body part 22 that has to be painted, possibly with outer parts of other opening parts that have to be painted and this assembly is painted in a painting line comprising painting tools (not shown). In this manner, the vehicle body comprising the vehicle body part 22 and the outer part(s) 4 of the opening part(s) is painted in a uniform manner in a single painting step. According to another embodiment, the outer part 4 can be painted without being mounted on the vehicle body part 22 but on the same painting line as the vehicle body part 22. The outer part 4 is for example attached to a support structure 30 attached to the vehicle body part 22 during the painting process. The support structure 30 is only used during painting to serve as a support of the outer part 4 and is removed from the vehicle body part 22 after painting to be reused on another vehicle body part 22. Alternatively, the support structure 30 is not attached to the vehicle body 22 and is simply placed in the vicinity of the vehicle body 22 on the painting line.

Once the outer part 4 has been painted, the inner part 2 is attached to the outer part 4 in the fastening area(s) 16. This step for example involves a demounting of the outer part 4 from the vehicle body part 22 if needed, as it is the case in the embodiment shown in Fig. 4.