WO1991001895A1

WO1991001895A1 - Process for drawing on a metal surface by material deposition

Info

Publication number: WO1991001895A1
Application number: PCT/FR1990/000587
Authority: WO
Inventors: Guy Aubertel; Robert Prodhon; Gérard RIVIERE
Original assignee: Guy Aubertel; Robert Prodhon; Riviere Gerard
Priority date: 1989-08-04
Filing date: 1990-08-03
Publication date: 1991-02-21
Also published as: FR2650521A1; FR2650521B1; EP0437587A1

Abstract

The invention relates to a process for drawing on a metal surface by material deposition. The process of the invention is especially noteworthy in that it consists in performing at least the following operations: C) coating the rough or other metal surface with an adherent coating (c) which, however, can be destroyed by a laser beam; D) burning said coating (c) at part (d), but substantially throughout its thickness, using a laser in accordance with a given design; E) if necessary, removing the burnt part of the coating and cleaning down to the lower surface to obtain a recessed design (e); G) coating said cleaned surface with another final layer (g).

Description

Method for drawing on a metal surface, by depositing material.

The invention relates to a method for drawing on a metal surface by depositing material.

In faucets, silverware or similar, it is common to carry out decorations. This is how it is possible to decorate all kinds of objects such as boxes, frames, jewelry, etc.

Apart from certain processes of the type, for example screen printing, which is not very solid, a known process consists in applying paints said to be cut (decoration by paint and varnish sparing).

After polishing and a suitable electrolytic treatment (nickel plating, gilding, silvering, chrome plating, etc.), the object is coated with a paint which is dried in the open air, cold (several hours), or hot at a temperature for example of about 80 degrees.

The object is then manipulated with gloves and using wet cotton to decorate by cutting the paint with a sharp tool. The paint is thus peeled off to reveal the previously treated base surface. Generally, the decor can only be very simple and most often comes down to large lines formed by two parallel cutting lines.

The object is then again protected by a colorless varnish, and the whole is polymerized between 60 and 180 degrees approximately.

It is easy to understand that all these operations are particularly delicate, while the possibilities of decoration are limited.

In addition, the adhesion is not perfect and it is limited in time.

Finally, we should note the enormous waste of such a process. Indeed, the decorative design which appears under the colorless varnish comes from the treated surface of the object, while the remaining surface, that is to say almost all of it, is hidden by the paint. To get a simple golden trickle there. it is necessary to carry out a total gilding of the surface to be decorated beforehand.

This is why the inventors have imagined a new process to draw on a metal surface, by deposition of material and which required research and a very special study to develop a removal of coating by means of a laser.

The method according to the invention is indeed remarkable in that it consists in performing at least the following operations:

C) coating the raw metal surface or not with a coating (c) adherent but destructible by laser beam;

D) partially burn (d), but over substantially its entire thickness, said coating (c) by means of a laser according to a determined drawing;

E) remove, if necessary, the burnt part of the coating and clean up to the surface below to obtain a hollow design (e);

G) coating said cleaned surface with another final coating (g).

In this way, it is clear that the visible decoration consists of the final added coating, unlike the prior art.

The laser is admittedly already known for certain uses and notam¬ ment cutting plate materials, but in this case, it is a appJ _r - ^cat - ^is quite new. Moreover, to obtain a good result, it was necessary to do research, studies and experiments in order to define in particular the power and the nature of the laser beam, as well as the suitable distance of the head from to the surface to be treated. Furthermore, for reasons mainly of reflection of the radius and of ejection of the burned materials, it appears advantageous that the laser head is moved relatively to the treated surface so that its axis deviates slightly and in permanence of normal to the plane of said surface at the point of impact. _S according to one embodiment, performs laser head relative to the surface to be treated, several passages slightly overlapping in the case of burning a portion of said surface whose dimensions are greater than the effective diameter of the laser beam. Advantageously, the operation E_ is carried out by abrasion. The process according to the invention may differ depending on the nature of the basic support, whether or not it is necessary to treat it beforehand. This basic support is generally metallic or comprises at least one metal layer. It can be in particular steel, stainless steel, copper, silver, gold, nickel, but generally it will be an alloy such as brass, nickel silver, "zamak", etc.

This is why an embodiment of the method according to the invention is remarkable in that the operation is preceded by an operation JF which consists in preparing the surface to be coated with the final coating (g), by applying a coating of primer (f) which is a function of the base metal (M).

In addition and according to the result to be obtained, the operation _G can be followed by an operation II which consists in destroying the coating (c) applied during the operation Ç_.

Preferably in this case, the operation Ç_ is preceded by an operation J3 which consists in applying a final coating (b) different from the final coating (g) and which becomes visible after the operation H. In this way, it is possible to obtain for example, gilding on a silver plating or on a black nickel plating, etc. Previously, operation 15 can be preceded by an operation _A which consists in preparing the surface to be coated with the final coating (b), by applying a primer coating (a) which depends on the base metal (M) . In all the cases where the aforementioned operation jH is carried out, it is possible, after this, to start again on the last final coating all the operations from operation _2.

Preferably, the coating (c) applied during the operation C_ is a polymerizable product, which is polymerized after its application, this product being, for example, a product based on an epoxy resin powder. However, with a laser and an appropriate setting, the coating (c) can also consist of at least a thin layer of certain metals, such as nickel and / or chromium, so that it can be obtained directly at the end of operation G_, a product whose appearance is for example similar to that which is obtained after operation II mentioned above.

More preferably, the final coating (b) of operation] 3 and / or the primer coating of operation _A are metallic and produced by electroplating, said final coating (b) of operation 15 being for example based on silver, gold, nickel or chromium.

Advantageously, the final coating (g) of operation G_ and optionally the primer coating (f) of operation F_ are metal- liques and applied preferably, but not exclusively, by galvano¬ plasty pad, said final coating (g) of the operation G_ being for example based on gold, silver, nickel, or chromium.

The invention will be clearly understood and other particularities will appear on reading the description which follows and which refers to the appended drawings in which:

FIG. 1 is a diagram of the method according to the invention,

FIG. 2 schematically shows a laser head in operation,

- Figure 3 corresponds to Figure 2 along a plane perpendicular and in top view relative to said Figure 2.

In Figure 1, we can see a base support (M), made of metal or comprising at least one surface layer of metal.

This metal support (M) can undergo numerous treatment operations. In FIG. 1, the various major specific operations according to the invention have been separated horizontally and have been referenced from A_ to H. Furthermore, according to the materials used and according to the desired result, each operation has been divided into three columns noted 1 to 3, so that each stage obtained can be referenced by the usual row-column notation, each stage being thus identified by the association of a letter and a number. It is clear that Figure 1 is designed to explain, the scales or proportions being completely arbitrary.

From the metallic support (M), it is possible to apply in C1 directly, during the operation referenced C_, a coating (c) preferably consisting of a polymerizable product, such as epoxy resin, the latter being, by example, in the form of a powder which is applied with a spray gun with electrostatic adhesion (it is also possible to use a liquid paint), then polymerized hot, while this layer represents, for example, 100 to 150 microns. As already said, this coating (c) could however be formed by one or more metallic layers. According to another embodiment of the method, the support (M) is coated with a final coating (b) in J32 and J33, the operation B2 here being preceded by an operation A2 which consists in making a coating of primer (a), for example a few microns of nickel on a support (M) of the brass type. These operations being carried out, one finds oneself in JC2 and 3 where one applies as specified above, a coating (c) of epoxy resin.

Operation 1) consists in burning part (d) of the epoxy coating, by means of a laser, as shown in FIGS. 2 and 3. These FIGS. 2 and 3 in fact represent a part 1 (here a cross-piece) of fittings), which of course has undergone the operations described above. The epoxy resin is burnt by means of a laser head 2 according to a predetermined drawing, here to simplify as shown in FIG. 3, a simple line 3 in order to subsequently obtain a decorative net. The end of the laser head is kept at a distance X (Figure 2) and moves relative to the part 1. The adverb "relati¬ vely" means that it is the head 2 and / or the part 1 which are moulted. Generally however, the part 1 is arranged on a support while the laser head 2 is mobile, the latter being, for example but not necessarily provided with five degrees of freedom.

As shown in Figure 3, the axis 4 of the laser head 2 made with a normal II to the surface to be treated at an acute angle W.

The angle W is then obviously that made by the laser beam shown in 5 (Figures 2 and 3) relative to the surface, so that the head 2 is not likely to receive in return a reflection of said ray, while allowing some ejection 6 of the calcined epoxy powder.

The adjustment of the laser power (for example 50 for a thickness to be treated of approximately 120 microns), the pressure of the compressed air (for example 1 bar), the focusing of the ray, the angle W, the distance X - are all factors on which we can obviously play. The verb "to burn", used here, must be taken in the most general sense possible, especially if the coating (c) to be destroyed is metallic; it should be understood as meaning "destroy by the laser beam".

The movements of the laser head are preferably computer assisted and it is understood that it is perfectly possible to iron several times in the same place and / or pass successively on contiguous and slightly overlapping portions so as to burn areas larger than the simple effective diameter of the laser beam at the point of impact. Figure 1 shows that operation I) once completed and which gives the three stages D1, D2 and D3_ depending on the case, is followed by operation 13 which consists in removing the burnt epoxy powder (d) to obtain the drawing sought in hollow (e), and we thus obtain, as the case may be, stages Kl., JΩ and E3 of FIG. 1. To remove the calcined debris, the inventors recommend abrading by means, for example, of a tools and an abrasive paste, in order to find the immediately lower surface (M in El. and b in E2 and E3). However, this operation may be more or less useful, since operation D may be sufficient to destroy all or almost all of the coating.

The following operation G_ consists, preferably after degreasing, of depositing a final coating (g) in the traces (e) previously obtained. The coating (g) is for example carried out by electroplating with a pad and the stages G'1, G2 and G3 are obtained.

This operation G_ can be preceded by an operation F_ (see FI) when the base metal (M) requires it, and which consists in applying a coating of primer (f), for example nickel on brass, in order to prepare the gilding or silvering of operation G_ (Gl stage).

It is understood that the stages Gl _^ and G'1 can be terminal stages, the object being decorated with a coating (g) in contrast with an epoxy coating (c).

On the other hand, the covering (b) which is found in columns 2 and 3 of FIG. 1 and which is chosen from a material different from that of the covering (g), must become visible. It can be, for example, for (b) nickel plating, chrome plating, silvering and for (g) gold plating.

In order to make the coating (b) visible, it suffices to provide an operation II which consists in destroying or dissolving the epoxy coating (c) so as to obtain the stages H2 and H3.

It is clear, however, that Operation II may eventually also be performed from the Gj stages. and G'1 to arrive respectively in Itt and H'1 in order to obtain for example a gilding (g) on a base for example (M) of solid silver or a silvering (g) on a base for example of brass ... (the possibility of this operation II from stages ^ and G'1 is indicated by dotted arrows in Figure 1).

Finally, from stages Hl_ and H'1, H2 and Ifë, it is possible to start again on the last coating (g) all the operations from C_, in order to carry out a new contrasting drawing on said coating (g) himself.

With a suitable metallic coating (c), for example nickel and / or chromium (or even chromium on a base of nickel plated brass), the result obtained in G_ may be substantially equivalent in appearance to the result obtained in. If the object 1 shown in Figures 2 and 3 is a piece of taps, it is clear that it could be any object: dishes, cutlery, boxes, ... The invention is certainly more particularly intended for decoration in fields such as (as already said), fittings, goldsmithing and even eyewear, but it also relates to all industries of surface treatment in general and of material deposition on a substrate metallic. This is the reason why we use the words "drawings" and "draw" rather than "decoration" and "decorate", the word "drawing" being to be taken in its broadest sense, because it could be, for example, an electronic circuit or the like.

Claims

1) Method for drawing a metal surface (M), by deposition of material, characterized in that it consists in performing at least the following operations:

E) remove, if necessary, the burnt part of the coating and clean up to the surface below to obtain a hollow design (e); G) coating said cleaned surface with another final coating (g).

2) Method according to claim 1, characterized in that for the _D operation the head (2) of the laser used is moved relative to the treated surface so that its axis (4) deviates slightly and permanently from normal NV ~~ "compared to the plane of said surface at the point of impact.

3) Method according to one of claims 1 and 2, characterized in that for operation J), the head (2) of the laser performs relatively on the surface to be treated, several passages slightly overlapping when it acts to burn a part of said surface whose dimensions are greater than the effective diameter of the laser beam.

4) Method according to one of claims 1 to 3, characterized in that the JE operation is carried out by abrasion.

5) Method according to one of claims 1 to 4 characterized in that the operation (_ {is preceded by a JF operation which consists in preparing the surface to be coated with the final coating (g), by applying a coating of primer (f) which is a function of the base metal (M).

6) Method according to one of claims 1 to 5, characterized in that the operation G_ is followed by an operation II which consists in destroying the coating (c) applied during the operation C_.

7) Method according to claim 6, characterized in that the operation C_ is preceded by an operation jî which consists in applying a final coating (b) different from the final coating (g) and which becomes visible after operation H.

8) Method according to claim 7, characterized in that the operation jî is preceded by an operation A _^ which consists in preparing the surface to be coated with the final coating (b), by applying a primer coating (a) which is a function of the base metal (M).

9) Method according to one of claims 6 to 8, characterized in that it consists, after operation II to start over on the last final coating all operations from the operation Ç_. 10) Method according to one of claims 1 to 9, characterized in that the coating (c) applied during the operation _C is a polymerizable product which is pol merit after its application.

11) Method according to one of claims 7 to 9, characterized in that the final coating (b) of operation J3 and / or the priming coating (a) of operation _A are metallic and made by galva ¬ noplasty.

12) Method according to claim 11, characterized in that the final coating (b) of operation J3 is based on silver, gold, nickel or chromium. 13) Method according to one of claims 1 to 12, caractéri¬ se in that the final coating (g) of the operation G_ and optionally the primer coating (f) of the operation JF are metallic and applied by electroplating to the pad.

14) Method according to claim 13, characterized in that the final coating (g) of the operation G_ is based on gold, silver, nickel or chromium.