METHOD FOR PRODUCING A DECORATIVE PART OF A MOTOR VEHICLE

Abstract

The invention relates to a method for producing a motor vehicle part (10) made of a plastic material, said method comprising a step of spraying a product, and the part comprising an area to be protected during the spraying. The method comprises the following steps: applying a fluid material forming a temporary masking layer on the area to be protected, said step being carried out automatically; spraying the product onto the part (10); and removing the temporary masking layer.

Claims

1-17. (canceled)

18. A method for producing a motor vehicle part made of plastic, the method comprising a step of spraying product and the part having an area to be protected during spraying, the method comprising: applying a fluid material forming a temporary masking layer on the area to be protected, this step being carried out automatically and the temporary masking layer comprising a hot melt glue or a peelable varnish; spraying the product onto the part; and removing the temporary masking layer.

19. The method according to claim 18, the temporary masking layer comprising a hot melt glue, method during which the part is hooked to a hooking jig during the step of spraying product and the temporary masking layer is pressed against the jig to be held by bonding on the jig.

20. The method according to claim 18, the temporary masking layer comprising a hot melt glue, method in which the temporary masking layer is applied at a temperature greater than 110 C., preferably between 140 C. and 220 C., and the temporary masking layer is removed at a temperature less than 90 C., preferably between 10 C. and 40 C.

21. The method according to claim 18, in which the step of removing the temporary masking layer is followed by a step of reusing the material which formed this temporary masking layer.

22. The method according to claim 18, the temporary masking layer comprising a hot melt glue having a melting point Tc that is relatively low compared with a melting point Tp of the sprayed product, for example the melting point Tc of the glue is less than 150 C., preferably less than 130 C., more preferably about 100 C.; and/or the melting point Tp of the sprayed product is a greater than 150 C., preferably greater than 180 C., more preferably about 200 C.

23. The method according to claim 18, wherein the step of reusing the temporary masking layer comprises the following steps: recovering the temporary masking layer after removing it, grinding it, drying it, introducing it into an extruder at a temperature T greater than the melting point of the masking layer and less than the melting point of the sprayed product, optionally adding an additive, for example one or more stabilizers in the masking layer, removing the product by filtering and/or recovering the material to form a new masking layer.

24. The method according to claim 18, wherein the hot melt glue is polyamide and the sprayed product is a polyurethane type polymer paint.

25. The method according to claim 18, in which the step of removing the temporary masking layer is followed by a step of degreasing and/or of surface treatment of the area to be protected.

26. The method according to claim 18, the temporary masking layer being deposited by a configurable robot to predefine the width and thickness of the temporary masking layer.

27. The method according to claim 18, wherein the part has a decorative surface coated with the sprayed product and the area to be protected is a local area of the decorative surface free of sprayed product.

28. The method according to claim 18, wherein the part is a decorative part, the area to be protected is an area for attaching another motor vehicle part, called part to be attached, and the step of removing the temporary masking layer is followed by a step of attaching the part to be attached to the attachment area of the decorative part.

29. The method according to claim 18, in which the part to be attached is attached by applying a glue on the attachment area of the decorative part.

30. The method according to claim 18, in which the part to be attached is attached by additive printing or 3D printing, by applying a bonding layer created by printing.

31. An installation for producing a motor vehicle part made of plastic, the installation comprising the following devices arranged one after another on a line for producing the motor vehicle part: a device for automatically applying fluid material forming a temporary masking layer on the part; a device for spraying product onto the part; and a device for removing the temporary masking layer.

32. The installation according to claim 31, comprising, after the device for removing the temporary masking layer, a station for reconditioning the temporary masking layer for reuse.

33. The installation according to claim 31, wherein the station for reconditioning the temporary masking layer comprises an extruder at a temperature T, T being greater than the melting point of the masking layer and less than the melting point of the sprayed product, and provided with a filter to separate the masking layer from the product.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The invention will be better understood on reading the accompanying figures, which are given solely by way of example and not limiting in any way, in which:

[0038] FIG. 1 is a diagrammatic exploded perspective view of a tailgate outer skin made according to one embodiment of the method and assembled on an interior tailgate lining,

[0039] FIG. 2 is an interior view of the outer skin of FIG. 1, and

[0040] FIG. 3 is a diagram illustrating a method for producing the outer skin of FIG. 1.

DETAILED DESCRIPTION

[0041] We refer to FIG. 1. A motor vehicle decorative part 10 produced according to the method described above may be a tailgate outer skin. This outer skin 10 is intended to be attached to a tailgate lining 12, so as to form a tailgate 14.

[0042] In this example, the decorative part 10 has two sections 10a, 10b: a lower outer skin 10a, for covering the lower section of the lining 12, and an upper outer skin 10b, for covering the upper section of the lining 12. The decorative part 10 is generally made of injected thermoplastic material, for example polypropylene. It has a decorative surface which is painted, visible from outside the vehicle, corresponding to the outer surfaces of the skins 10a and 10b, illustrated diagrammatically on FIG. 1. It also has an inner surface corresponding to the inner surfaces of the skins 10a and 10b, illustrated diagrammatically on FIG. 2. The inner surface of the skins 10a, 10b is not intended to be visible once the tailgate is assembled and mounted on the motor vehicle. It is a surface which can be qualified as technical, in the sense that it is not intended for decoration and may therefore have technical features including means for attaching the decorative part 10 to the tailgate lining 12.

[0043] The tailgate lining 12 has the general shape of a frame having an opening 16 for receiving a rear window. This tailgate lining 12 is for example made of a reinforced thermosetting material.

[0044] In this example, the decorative part 10 is attached to the tailgate lining 12 by bonding. The decorative part 10 therefore has two areas to be protected 18a and 18b, i.e. attachment areas 18a and 18b, arranged respectively on the inner surface of the skins 10a, 10b. The attachment areas 18a and 18b are shown in dotted lines on FIG. 2. At the end of the method for producing the decorative part 10, these attachment areas 18a and 18b will be covered with bonding tracks, then bonded to the tailgate lining 12 to permanently attach the decorative part 10 to the tailgate lining 12.

[0045] The method for producing the decorative part 10 will now be described, with reference to FIG. 3. It is understood that the steps for producing the decorative part 10 are described generally for simplification purposes, but these steps are implemented firstly on the lower skin 10a, secondly on the upper skin 10b, generally independently.

[0046] The method starts by an injection 20 of material in a mold to form the body of the decorative part 10 by molding, more precisely to form firstly the lower skin 10a and secondly the upper skin 10b. Before painting the decorative part 10, a step 22 is carried out in which a temporary masking layer 22a, 22b is applied on the area to be protected 18a, 18b. Step 22 is carried out automatically by a robot. The layer 22a, 22b is produced at the same position as the area to be protected 18a, 18b. Thus, it is shown fictitiously on FIG. 2, although it is not present on the final decorative part 10 shown on FIG. 2.

[0047] In this example, the temporary masking layer 22a, 22b comprises a hot melt glue as described above. The step 22 of applying the temporary masking layer 22a, 22b is carried out at a temperature greater than 110 C., preferably between 140 C. and 220 C., more preferably between 150 C. and 200 C. Furthermore, step 22 is carried out by a configurable robot to predefine the width and thickness of the temporary masking layer 22a, 22b. For example, the width of the layer 22a, 22b is about 20 mm and the thickness is between 1 mm and 3 mm. In this case, the robot displacement speed is between 50 mm and 200 mm per second, with a glue flow rate of between 20 and 80 rpm (revolutions per minute). Furthermore, the layer is applied by means of an extended nozzle positioned as close as possible to the part, with a distance of between 2 mm and 8 mm between the part and the end of the nozzle. The glue is therefore deposited more precisely. In addition, so that the layer can be spread over a bonding track of a certain length, for example 25 mm, the viscosity of the glue can be varied, depending on the glue temperature, type and reference.

[0048] The step 22 of applying the temporary masking layer 22a, 22b on the area to be protected 18a, 18b is followed by a step 24 in which a product, in this case paint, is sprayed onto the decorative part. This step 24 is carried out by spraying paint onto the decorative surface corresponding to the outer surfaces of the skins 10a and 10b. In this example of spraying paint, step 24 includes a step of curing in an oven for a period between 20 and 30 minutes per part and is carried out at a temperature of about 80 C. The inner surfaces of the skins 10a and 10b are not painted directly, but indirectly receive paint residues deposited in the form of a thin film, due to the paint mist generated by spraying. Thus, the temporary masking layer 22a, 22b, which is sealed at this temperature, probably receives paint droplets instead of the area to be protected 18a, 18b that it covers.

[0049] According to a particularly advantageous improvement, during step 24 of applying paint, the decorative part 10a, 10b is hooked to a hooking jig and the temporary masking layer 22a, 22b is pressed against the jig to be held by bonding on the jig.

[0050] Step 24 of spraying product is followed by a step 26 in which the temporary masking layer 22a, 22b is removed. For example, the end of the layer is raised and pulled. This step of removing the layer 22a, 22b is carried out at a temperature less than 90 C., preferably between 10 C. and 40 C. At this temperature, the hot melt glue forming the layer 22a, 22b is cooled and flexible and can be removed quickly and easily without fragmenting.

[0051] Step 26 of removing the temporary masking layer is followed by a step 30 of degreasing, and optionally of surface treatment of the attachment area.

[0052] According to a particularly advantageous embodiment, the step 26 of removing the temporary masking layer is also followed by a step 28 of reusing the material which formed this temporary masking layer. According to an example, the temporary masking layer comprises a hot melt glue having a melting point Tc that is relatively low compared with a melting point Tp of the sprayed product. According to an example, the hot melt glue is polyamide (PA) of melting point Tc about 100 C., and the sprayed product is a polyurethane type polymer paint of melting point Tp about 200 C. The step 28 of reusing the temporary masking layer comprises the following steps: recovering the temporary masking layer after removing it, grinding it, drying it, introducing it into an extruder at a temperature T of about 120 C.-130 C., therefore greater than the melting point Tc of the masking layer and less than the melting point of the sprayed product. Thus, the masking layer melts, but not the sprayed product. The product is then removed at end of extrusion by filtration using a coarse rotary filter to separate the masking layer from the product. The material is then recovered to form a new masking layer. Advantageously, during extrusion, an additive can be added, for example, stabilizers and/or other additives, to the masking layer so that it can be recycled several times.

[0053] Step 30 is then followed by a step 32 in which the part to be attached is attached to the attachment area of the decorative part, i.e. in this example a step in which the tailgate lining 12 is attached to the attachment area 18a, 18b of the decorative part 10. The attachment areas 12a, 12b have been shown diagrammatically on FIG. 1.

[0054] At the end of this step 32, the tailgate 14 is obtained, ready to be assembled on the vehicle.

[0055] Such a production method is implemented on an installation comprising the following devices arranged one after another on a line for producing the part 10. [0056] a device for automatically applying fluid material forming a temporary masking layer 22a, 22b on the part, [0057] a device for spraying product onto the part 10, [0058] a device for removing the temporary masking layer 22a, 22b.

[0059] In addition, the installation preferably includes a station for reconditioning the temporary masking layer for reuse. Advantageously, this station comprises an extruder at a temperature T, T being greater than the melting point of the masking layer and less than the melting point of the sprayed product, and provided with a filter, optionally a rotary filter, to separate the masking layer from the product. The filter is preferably coarse, i.e. with filter meshes of between 150 m and 600 m (micrometers).

[0060] According to another embodiment, the part to be produced has a decorative surface coated with the sprayed product and the area to be protected is a local area of the decorative surface free of sprayed product. For example, the outer surfaces of the skins 10a and 10b of the decorative part 10 have a local unpainted area, free of paint and which is to be protected in the same way as the areas to be protected 18a, 18b. It is understood that the method described above applies similarly to such areas to be protected and that the entire description can be read with such an application.

[0061] The invention is not limited to the embodiments described and other embodiments will be clearly apparent to those skilled in the art.

[0062] In particular, the method is used to manufacture a tailgate skin 10 but many other parts can be produced using this method, in particular a front or rear bumper skin, a front or rear wing, a window pillar, a rocker box, a side door, a bonnet, a convergent such as a roof spoiler.

[0063] In addition, according to another example, the temporary masking layer 22a, 22b comprises a peelable varnish instead of the hot melt glue. For example, a peelable varnish such as that marketed by the company Zuelch under reference 826-W1272-00 is used. This varnish is deposited automatically, with a drying time of about two hours at ambient temperature. The drying time can be reduced by increasing the temperature, for example 15 minutes drying at a temperature of about 140 C.

[0064] Furthermore, the attachment of the decorative part 10 and of the part to be attached 12 is, in the example described above, by bonding, but other types of attachment are possible, in particular other types of attachment by surface bonding requiring a very clean surface to be attached, with no residues. In particular, attachment by mechanical hooking on a relatively large area can be considered, during which a bonding layer produced by additive printing or 3D printing is applied to the attachment area, in order to hook the part to be attached to the decorative part 10.