FR3060448A1 - PLASTIC COMPONENT OF A MOTOR VEHICLE HAVING ELECTRICALLY CONDUCTING ELEMENTS DISTRIBUTED ON ITS SURFACE - Google Patents

Abstract

Part (1) made of plastic of a motor vehicle, on which a finishing coating is to be applied, and which is coated, prior to the application of the finishing coating, with a conductive primer rendering its surface electrically conductive to paint, characterized in that it comprises electrically conductive elements distributed on its surface such that the distance between any point of this surface and the nearest electrical conducting element is at most 80 cm. Transport system for a workpiece to be painted, provided with at least one swing (11) for carrying a piece (1) of motor vehicle plastic material while the workpiece is undergoing a finishing coating operation, and provided with a grounding means adapted to provide an electrical connection with the conductive ground of the earth. It comprises a plurality of electrical contactors for electrically connecting the grounding means to electrical conductor elements of the part, and in that there is a distance of at most 80 cm between two adjacent electrical contactors (35).

Description

® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number:

(to be used only for reproduction orders)

©) National registration number

060 448

62497

COURBEVOIE © Int Cl ⁸ : B 32 B 37/14 (2017.01), B 60 R 13/00, C 09 D 5/46, B 05 D 3/02

A1 PATENT APPLICATION

©) Date of filing: 15.12.16. © Applicant (s): COMPAGNIE PLASTIC OMNIUM (30) Priority: Public limited company - FR. @ Inventor (s): VIDAL SOPHIE, VIOT FREDERIC and JACQUEMET THIERRY. (43) Date of public availability of the request: 22.06.18 Bulletin 18/25. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ® Holder (s): COMPAGNIE PLASTIC OMNIUM related: Anonimous society. ©) Extension request (s): (© Agent (s): LLR.

164) PIECE IN PLASTIC MATERIAL OF MOTOR VEHICLE PROVIDED WITH ELECTRICALLY CONDUCTIVE ELEMENTS DISTRIBUTED ON ITS SURFACE.

FR 3 060 448 - A1 (5 /) Part (1) of motor vehicle plastic, to which a finish coating must be applied, and which is coated, prior to the application of the finish coating, with a primer conductor making its surface to be painted electrically conductive, characterized in that it comprises electrically conductive elements distributed over its surface in such a way that the distance between any point on this surface and the nearest electrically conductive element is at maximum of 80 cm.

Transport system for a part to be painted, provided with at least one swing (11) for carrying a part (1) made of plastic material of a motor vehicle while this part is undergoing an operation for applying a finishing coating, and provided with a grounding means capable of ensuring an electrical connection with the conductive ground of the earth. It comprises several electrical contactors for electrically connecting the grounding means to electrical conductive elements of the room, and in that there is a distance of at most 80 cm between two neighboring electrical contactors (35).

- 1 [0001] The present invention relates to the technical field of motor vehicle parts intended to be coated with a coating applied by projection of particles, and in particular the field of parts intended to be painted and in particular body parts.

In the prior art, it is known that the body parts are painted on a paint line by spraying paint droplets, then baking this paint in an oven for crosslinking and forming a smooth and uniform layer. . The paint droplets are electrically charged so as to be attracted, by electrostatic force, preferably towards the part, which is kept grounded, so as to limit the losses of paint. Indeed, the attraction of the droplets aims to avoid as much as possible that the projected droplets do not reach the part to be painted and fall on the ground, where they are lost. Maintaining a sufficient potential difference between the part and the droplets requires that, prior to projection, the part be covered with a conductive primer which gives it an electrically conductive surface to be painted, and that this surface be mass during projection. This earthing goes through the parts transport system, which supports the parts to be painted during the projection of the paint, then during cooking.

A drawback of the state of the art is that the distribution of the paint droplets at the end of the spraying can be improved. The inventors have discovered that an important cause of poor distribution of the droplets is that the conductivity of the part to be painted is not always as satisfactory as expected. Conventionally, the resistivity of the standard conductive primer layer is 1 megaohm, for a thickness of between 10 and 30 microns, with a distance between the measurement electrodes of 25 mm.

An object of the invention is to solve this problem of resistivity of the parts to be painted.

An object of the invention is a plastic part of a motor vehicle, on which a finishing coating must be applied, and which is coated, prior to the application of the finishing coating, with a conductive primer rendering its electrically conductive surface to be painted, characterized in that it comprises electrically conductive elements distributed over its surface in such a way that the distance between any point on this surface and the nearest electrically conductive element is at most 80 cm.

By surface of a part is meant all of the points of the part which delimit it, that is to say its two large faces, internal and external, as well as its

- 2 slice. The surface to be painted is the subset of the points intended to receive the application of a paint. This surface may include the edge of the piece, which is sometimes referred to as the outline of the piece.

According to a particular embodiment of the part, at least one of the electrically conductive elements is a metal insert overmolded during the shaping of the plastic material constituting the part.

According to a particular embodiment of the part, the overmolded metal insert is an eyelet, a plate, a braid.

In the case of a metal braid, provision is advantageously made to connect the latter to the mast of a transport system comprising said mast and at least one swing.

According to a particular embodiment of the part, the overmolded metal insert is located in a part of the part to be painted which is simply demouldable.

By part of a part which is simply demouldable is meant a part of a part which can be extracted from a mold comprising a die and a punch, after separation of the matrix and the punch, without requiring displacement of any part of the matrix. In other words, the opening of the mold is sufficient to release the part of the part in question and it is not necessary to provide for movements of blocks or drawers inside the mold which would prevent the extraction of the part. .

According to a particular embodiment of the part, at least one of the electrically conductive elements is an insert and fixed on the part after the plastic material constituting the part has been shaped.

According to a particular embodiment of the part, the insert is a conductive adhesive film.

According to a particular embodiment of the part, the insert is a layer of superconductive primer.

According to a particular embodiment of the part, the primary

- 3 superconductors have a resistance of less than 20 kiloohms at 300 K when it has a thickness of between 10 and 30 microns, with a distance between the measurement electrodes of 25 mm, and preferably less than 5 kiloohms, and, even more preferably, less than 3 kiloohms.

Of course, the primary superconductor has a non-zero resistance, otherwise it would not produce heat by the Joule effect, but its resistance, measured under the conditions specified above, is significantly less than 1 megaohm of the standard primary conductor used in the state of the art on paint chains.

According to a particular embodiment of the part, the primary superconductor is enriched with electrically conductive charges.

According to a particular embodiment of the part, the electrically conductive charges are chosen alone or in combination from the following group of charges: graphite, metals, such as copper, silver, iron, indium, alloy of graphite and metal , carbon black.

According to a particular embodiment of the part, the electrically conductive charges are present in the primary at a rate of 10% by weight, preferably between 20% and 60% by weight.

According to a particular embodiment of the part, the insert is located in a part of the part to be painted which is not simply demouldable.

By part of a part which is not simply demouldable is meant a part of a part which cannot be extracted from a mold comprising a die and a punch, after separation of the matrix and the punch, only after displacement d 'a sub-part of the matrix. In other words, the opening of the mold is not sufficient to release the part of the part in question and it is necessary to provide for movements of blocks or drawers inside the mold to make it possible to extract the part. .

According to a particular embodiment of the part, the part is a part of the exterior bodywork of a motor vehicle.

According to a particular embodiment of the part, the bodywork part

- 4 is a bumper skin or a spoiler.

According to a particular embodiment of the part, the plastic material is chosen from the list consisting of: polypropylene; acrylonitrile butadiene styrene / polycarbonate; polycarbonate / polyethylene terephthalate; polycarbonate; polyamide; polyester; P / E copolymer.

According to a particular embodiment of the part, the plastic is loaded with elastomer or mineral fillers.

Another object of the invention is a system for transporting a part to be painted, provided with at least one swing to carry a plastic part of a motor vehicle while this part is undergoing an application operation. '' a finishing coating, and provided with a grounding means capable of ensuring an electrical connection with the conductive ground of the earth, characterized in that it comprises several electrical contactors for electrically connecting the grounding means ground to electrically conductive parts of the room, and in that there is a maximum distance of 80 cm between two neighboring electric contactors.

An advantage of the distance of a maximum of 80 cm is that the grounding of the part to be coated is ensured in a homogeneous manner, with zones of the part less conductive than others, therefore without accumulation of charges. in areas of the room that, if it did, would become less attractive to the sprayed paint droplets.

We measure the benefits of improved grounding of the part to be coated by a decrease in the amount of paint droplets which do not reach the part carried by the swing. The gain is expressed as a percentage loss, which goes from a value of around 55% under standard conditions to around 45% thanks to the invention.

According to a particular embodiment of the system for transporting a part to be painted, the electrical contactors comprise at least one metal pin located on the swing.

According to a particular embodiment of the system for transporting a part to be painted, the electrical contactors comprise at least one electrical cable.

The invention will be better understood on reading the appended figures, which are provided by way of examples and have no limiting character, in which:

FIG. 1 is a perspective view of a bumper skin, seen from the inside and carried by a paint chain swing, the mast of which is not shown,

FIG. 2 is a perspective view of the mast of a transport system and of a part to be painted before it is carried by a swing,

FIG. 3 is a close-up view of part III of the swing in FIG. 1,

FIG. 4 is a close-up view of part IV showing a pin of the swing in FIG. 3.

The bumper skin 1 shown in the figures is a part 1 made of plastic of a motor vehicle, which has an elongated shape, with a central part 3 hollowed out, two lateral brackets 5 and a faceplate 7. This particular shape is in no way limiting the scope of the invention.

Openings 9 are provided for optics (not shown), sensors (not shown) or other members (not shown) of the vehicle, which will not be detailed here.

The system 11 for transporting a part to be painted is formed of a metal mast 12 (formed by two uprights, visible in Figure 2) carrying swings 13 (including one visible in Figure 1). Each swing is a metallic structure, electrically conductive, obtained by welding together metallic tubes of square section and metallic tubes of circular section, these sections of course not being limiting.

The metal structures being conductive, like the mast 12, the transport system 11 may constitute its own means of grounding.

Each swing has a central part 3 comprising two branches 15 by which the swing is mounted on the mast 12. The two branches 15 are connected by a cross member 17. Two gantries 19 leave the branches 15, upwards and towards the 'before (relative to the usual directions of movement of the vehicle).

The swing extends, on the opposite sides of the gantries 19 and branches 15, by tubes of circular section - this circular section is smaller

- 6 as the square section - towards supports intended to support the bumper 1 skin in different places:

- upwards to maintain a circular cross-section tube serving as a support for the plastron for the rear edge 31 of the plastron 7,

- towards the sides to serve as a support 23 for the lateral part of the bumper skin 1, up to the top of its lateral brackets 5.

The swing further comprises extensions to reach the bumper skin 1:

- at two high points 25 located substantially vertically above the gantries 19,

- at the two lower corners 27 of the lateral hooks 5,

- at two internal points 29 located on an edge 31 of the central recess of the bumper skin 1.

These points do not correspond to places of support for the bumper skin 1, but to areas 33 of electrical contact between the arm and the bumper skin 1. Other points having the same function are provided on the support 21 of the plastron and on the support 23 of the lateral part. In correspondence with each of these electrical contact zones 33, the arm of the swing comprises electrical contactors 35.

The eight areas of electrical contact closest to the arm - that is to say those located on the support 21 of the front plate, those located at the right of the gantries 19, those located on the edge 31 of the recess and those located on the upper edge 31, next to the faceplate 7, are partly simply demouldable from the bumper skin 1, while the other four contact zones, located in the upper and lower corners of the sticks, are in part of the bumper skin that is not simply demouldable 1.

Due to the constraints associated with molding techniques, the invention allows the electrical contact zones 33 located in the non-demoldable zone to be provided with electrically conductive elements 37 added after shaping of the bumper skin 1 , for example by local application of a superconductive primer, which ensures a conductivity of the surface to be painted such that the resistivity of the superconductive primer layer is less than 2 kiloohms at 300 K when the superconductive primer layer has a thickness between 10 and 30 microns, with a distance between the measuring electrodes of 25 mm. In a variant, the electrically conductive element 37 may consist of a conductive adhesive strip which forms an adhesive film on the skin of bumper 1.

- 7 In the simply demoldable parts of the bumper skin 1, the electrically conductive elements 37 can be molded inserts during the molding of the bumper skin 1. These inserts can be chosen from the following list : carnation; plate ; metallic braid.

The superconductive primary, the adhesive strip, the eyelets and the plate constitute electrical conductive elements 37.

The electrically conductive elements 37 of the bumper skin 1 are all distributed over the surface of the latter so that the distance between any point on this surface and the nearest electric conductive element 37 or at most 80 cm. Consequently, on the transport system 11, the distance between two neighboring electrical contactors 35 serving for the same part to be painted is also at most 80 cm.

The mast 12 of Figure 2 has an electric cable 38a which is electrically connected to it and which leads to an alligator clip 38b intended to pinch the bumper skin 1 in a part thereof comprising a conductive element electric 37. This part of the room, which will not be painted due to the presence of the alligator clip 38b, is a non-visible area of the room, that is to say an area which will be hidden from the eyes of users when the part is ultimately mounted on the vehicle.

In Figure 3, there is shown part III of Figure 1, which shows some of the tubes serving as support 23 of the side portion of the swing, provided with a pin 38c. This pin 38c constitutes an alternative to the electric cable 38a of FIG. 2 and makes it possible to put the layer of primary conductor at the electrical potential of the swing, which is in turn connected to the ground, at conventionally zero potential, by the mast 12 which the door.

In Figure 4, we see that the pin 38c is arranged to create a good quality electrical contact between the support 23 of the side part and the bumper skin 1. When the bumper skin 1 is in place on the swing, the pin 38c comes into contact with an electrically conductive element 37.

Thanks to the combination, on the bumper skin 1, of elements

- 8 electrical conductors 37 overmoulded or added, it is ensured that any point of the part to be painted is grounded homogeneously by checking that it is less than 80 cm away from such an electrically conductive element 37. Thus , it is ensured that no portion of the part to be painted is electrically charged during the spraying of paint droplets, which guarantees not only a low loss of paint, but also a good distribution of the droplets on this surface.

In the example which has just been described, the finishing coating which must be applied to the part is a paint, but other coatings are possible.

The invention is not limited to the embodiments described.

References used in the drawings

Reference Designated object

... bumper skin

I ... Motor vehicle plastic part

... Central part

... lateral crosses

... Chestplate

... Openings

II ... Transport system

... mast

... Swings

... Branches

... crosses

... Gantry cranes

... Chest support

... Side support

... High points

... two lower corners

... Internal points

... Edge

... electrical contact areas

... Electric contactors

... Electrically conductive elements

... Electrically conductive element

38a. . . Electric cable

38b. . . Alligator clip

38c. . . Pionpeindre

Claims (16)

Claims 1. Piece (1) of motor vehicle plastic, to which a finish coating must be applied, and which is coated, prior to the application of the finish coating, with a conductive primer making its surface to be painted electrically conductive , characterized in that it comprises electrically conductive elements (37) distributed over its surface so that the distance between any point on this surface and the nearest electrically conductive element (37) is at most 80 cm. 2. Part according to claim 1, wherein at least one of the electrically conductive elements (37) is a metal insert overmolded during the shaping of the plastic material constituting the part. 3. Piece according to claim 2, wherein the overmolded metal insert is an eyelet, a plate, a braid. 4. Part according to any one of claims 2 and 3, wherein the overmolded metal insert is located in a part of the part to be painted which is simply demouldable. 5. Part according to any one of claims 1, 2, 3 and 4, wherein at least one of the electrically conductive elements (37) is an insert and fixed on the part after the shaping of the plastic constituting the room. 6. Part according to claim 5, wherein the insert is a conductive adhesive film. 7. Part according to any one of claims 5 and 6, wherein the insert is a layer of superconductive primer. 8. Part according to claim 7, in which the superconducting primary has a resistance of less than 20 kiloohms at 300 K when it has a thickness of between 10 and 30 microns, with a distance between the measurement electrodes of 25 mm, and of preferably less than 5 kiloohms, and even more preferably less than 3 kiloohms. 9. Part according to any one of claims 7 and 8, wherein the superconductive primary is enriched in electrically conductive charges. 10. Part according to claim 9, wherein the electrically conductive charges are chosen alone or in combination from the following group of charges: graphite, metals, such as copper, silver, iron, indium, graphite and metal alloy, black of carbon. 11. Part according to any one of claims 9 and 10, in which the electrically conductive charges are present in the primary at a rate of 10% in -11 weight, preferably between 20% and 60% by weight. 12. Part according to any one of claims 5, 6, 7, 8, 9, 10 and 11, wherein the insert is located in a part of the part to be painted which is not simply demouldable. 5 13. Part according to any one of claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12, wherein the part is a part of the exterior bodywork of a motor vehicle. 14. System for transporting a part to be painted, provided with at least one swing (11) for carrying a part (1) of plastic material of a motor vehicle while 10 this part undergoes a finishing coating application operation, and provided with a grounding means capable of ensuring an electrical connection with the conductive ground of the earth, characterized in that it comprises several contactors electric (35) for electrically connecting the grounding means to electrically conductive elements (37) of the room, and that there is a distance 15 of a maximum of 80 cm between two neighboring electrical contactors (35). 15. A system for transporting a part to be painted according to claim 14, in which the electrical contactors (35) comprise at least one metal pin (38c) located on the swing. 16. A system for transporting a part to be painted according to claim 14, in which the electrical contactors (35) comprise at least one electrical cable (38a). 1/2 2/2