WO1995005100A1

WO1995005100A1 - Method for the fabrication of multicolor metal parts such as coins, medals or tokens

Info

Publication number: WO1995005100A1
Application number: PCT/FR1994/000943
Authority: WO
Inventors: Jean-Paul Guerlet
Original assignee: Comptoir Lyon-Alemand-Louyot
Priority date: 1993-08-12
Filing date: 1994-07-27
Publication date: 1995-02-23
Also published as: FR2708836A1; FR2708836B1

Abstract

The present invention relates to a method for the fabrication of multicolor metal pieces such as particularly coins, medals or tokens. According to the invention, the method is substantially characterized in that it comprises the assembly, known per se, of at least two parts made of metal alloys having the same qualitative composition but different in their quantitative composition, the nature of said alloys and their quantitative composition being selected so as to obtain a color contrast. The invention also relates to a method for recycling and reusing an alloy based on copper and nickel as well as the utilisation of nickel silver alloys Cu-Ni-Zn for the fabrication of such metal multicolor pieces.

Description

Process for the production of multi-colored metallic coins, such as in particular coins, medals or tokens.

The subject of the present invention is a new process for the manufacture of multicolored metallic coins, such as in particular coins, medals or tokens.

This process is mainly intended for the production of two-color or three-color parts.

Two-tone pieces are generally composed of a central core and a peripheral crown, made of metal alloys from very different families in terms of their qualitative compositions, in order to obtain a color contrast.

In the case of tricolor pieces, a central pawn is generally added in the heart of the piece. The manufacture of such multicolored metal parts has raised an important technical problem due to the difficulty of assembling or joining together the different materials constituting the part.

Various solutions have been proposed in the prior art to resolve this difficulty. Reference may in particular be made to the documents FR 2 611 157 and EP-0 312 436 incorporated here by reference.

These methods are perfectly suited for joining together, most often by mechanical connection, the various constituent parts of the part.

However, these known methods are not at all suitable for recycling or recovering these coins which is generally desirable, in particular in the case of coins, when these are demonetized.

Indeed, due to the quality of the mechanical connection obtained by the implementation of these known methods, the separation of the various constituent parts of the part requires a long and costly mechanical treatment, which one will seek to avoid in practice . In some cases, such as that of a two-tone piece composed of a central nickel core and a peripheral crown made of a CuAlNi6-2 alloy, theoretically possible recycling cannot be practiced for economic reasons. Under these conditions, the only possibility envisaged so far, to recover the multicolored parts after demonetization, consists in remelting these parts and in recovering by refining and separation of each of its constituent elements. However, this process is also expensive.

Under these conditions, the aim of the present invention is to solve the technical problem consisting in providing a process for manufacturing multicolored metal parts of a new design, which guarantees a secure connection between the various constituent parts of the part, while by allowing easy recycling of the parts thus manufactured in particular so that they can be reused for the manufacture of other parts.

The method according to the present invention, making it possible to solve this technical problem, consists in assembling, in a manner known per se, at least two parts made of metal alloys of the same qualitative composition, but different in their quantitative composition, the nature of these alloys and their quantitative composition being chosen so as to obtain a color contrast.

Thus, unlike previous methods according to which the color contrast between the constituent parts of the parts resulted from the use of alloys of different qualitative and quantitative compositions, the originality of the invention lies in the use of a single family of alloys comprising the same basic constituents but making it possible to obtain different colors according to the relative proportions of its constituents.

As can be understood, this process according to the invention allows easy recycling of the parts which does not require separation of their constituent parts and which also allows the reuse of the materials constituting them for the manufacture of new parts.

According to a currently preferred embodiment of the invention, the alloys used for the manufacture of the constituent parts of the parts are copper-nickel-zinc alloys belonging to the family of nickel silver.

Such ternary alloys are entirely suitable for implementing the method according to the invention, since it is possible, by varying the relative proportions of these three constituent elements, to obtain a range of colors from red to white, passing through rosé and yellow. Thus, according to a particular characteristic, the method according to the invention allows the production of a two-color piece comprising a central core made up of an alloy comprising, expressed by weight, 25% of nickel, 15% of zinc and 60% copper; and a peripheral crown made of an alloy comprising, expressed by weight, 7.5% nickel, 25% zinc and 67.5% copper.

According to another particular characteristic, the method according to the invention allows the production of a two-tone part comprising a central core made of an alloy comprising, expressed by weight 25% of nickel, 15% of zinc and 60% of copper, and a peripheral crown made of an alloy comprising, expressed by weight, 7.5% of nickel, 5% of zinc and 87.5% of copper.

Of course, other compositions make it possible to obtain the desired color contrast.

Those skilled in the art can easily reconstruct them using for example the single appended figure, which partially represents the ternary Cu-Ni-Zn diagram and shows the different colors which can be obtained by varying the relative proportions of each of these. elements.

These alloys allow, in particular, access to red, pink, yellow and white colors, generally used in the monetary field.

The various constituent parts of the part can be assembled, within the framework of the present invention, by any known method, such as for example those described in documents FR 2 611 157 and EP-0 312 436 mentioned previously.

The parts produced according to the process according to the invention can be easily reused. Thus, these parts can be remelted and reused for the fabrication of other parts, in particular in the form of an alloy corresponding to that which forms one or the other of its constituent parts, such an alloy possibly being easily obtained by adding previously calculated proportions of copper, nickel and zinc to the melt. Consequently, according to a second aspect, the present invention aims to cover, as a new product, a recyclable multicolored metallic coin, such as in particular a coin, a medal or a token, of the type comprising at least two parts of different color, capable of being obtained according to the method described above, and characterized in that said parts are produced in metallic alloys of the same qualitative composition, but different in their quantitative composition, the nature of these alloys and their quantitative composition being such that they make it possible to obtain a color contrast. Advantageously, the aforementioned alloys are copper-nickel-zinc alloys belonging to the family of nickel silver.

According to a particular characteristic, this part is two-tone and has a central core made of an alloy comprising, expressed by weight, 25% of nickel, 15% of zinc and 60% of copper, and a peripheral crown made up of a alloy comprising, expressed by weight, 7.5% nickel, 25% zinc and 67.5% copper.

According to another characteristic, this part is two-tone and comprises a central core made of an alloy comprising, expressed by weight 25% of nickel,

15% zinc and 60% copper, and a peripheral crown made of an alloy comprising, expressed by weight, 7.5% nickel, 5% zinc and 87.5% copper.

According to yet another characteristic, this part is two-tone and has a central core made of an alloy comprising, expressed by weight 11% nickel, 26% zinc and 63% copper, and a peripheral crown made up of a alloy comprising, expressed by weight 5.5% nickel, 24.5% zinc and 70% copper.

A particular advantage of the process according to the present invention lies in the fact that the latter allows the reuse of demonetized parts made of a Cu-Ni alloy 75/25, which is the white alloy currently most used in the world, such as monetary alloy.

Indeed, by adding to this copper and nickel based alloy, previously calculated quantities of copper and zinc, it is possible to manufacture by fusion nickel silver alloys capable of being used in the context of the present invention, for the manufacture of two-color or three-color parts, the latter being themselves recyclable.

Thus, according to a third aspect, the present invention aims to cover a process for the recycling and reuse of alloys based on copper and nickel, such as in particular the alloy Cu-Ni 75/25, characterized in that it consists of transforming said alloy into a nickel silver alloy, for example by fusion, by adding previously calculated quantities of copper and zinc.

Another particularly important advantage of the process according to the invention lies in the mode of connection between the constituent parts of the part. Indeed, the minting of monetary or other coins, is generally done from an annealed condition.

The constituent parts of the part being produced, according to the invention, from alloys having the same qualitative composition, the annealing operation leads to a very clear improvement in the connection between the different parts of the part, by preferential diffusion. of one of the constituents of a part of the part, to the adjacent part, and vice versa.

In the case of copper-nickel-zinc alloys, it is zinc which will have the greatest mobility and which will help to perfect the connection between two parts of the part. This diffusion contributes significantly to the joining together of the two parts of the room.

According to a fourth aspect, the present invention aims to cover the use of nickel silver Cu-Ni-Zn alloys, for the manufacture of multicolored metal parts, such as in particular coins, medals and tokens. The invention will be illustrated in more detail by the following examples.

In these examples, the proportions are expressed by weight, unless otherwise indicated.

Example 1: The method described in document FR 2 611 157 is used to constitute a two-colored part.

The alloy used to constitute the core of the part has the following composition, expressed by weight: nickel: 25% zinc: 15% copper: 60%.

This alloy has a white color.

The alloy used to constitute the peripheral crown has the following composition, expressed by weight: nickel: 7.5% zinc: 25% copper: 67.5%.

The latter alloy has a yellow color. This part can be easily recycled and reused.

In this regard, it will suffice to add, during the melting of the part, either nickel or zinc, in previously calculated proportions, to obtain one of the two alloys constituting the part.

Example 2:

Using the same operating mode as that described in the example, a two-color white and pink recyclable part can be produced.

The core will be made of the same alloy as that described in Example 1.

The alloy constituting the peripheral crown has the following composition, expressed by weight: nickel: 7.5% zinc: 5% copper: 87.5%.

This alloy has a pink color. The process which has just been described therefore provides a satisfactory solution to the technical problem posed, since it makes it possible to manufacture multicolored metallic parts capable of being easily recycled, without the need for separation of their constituent parts, and susceptible can be reused for the manufacture of other parts.

Example 3

Using the same procedure as that described in Example 1, a two-color white and yellow recyclable part can be produced.

The alloy used to constitute the core of the part has the following composition, expressed by weight: nickel: 11% zinc: 26% copper: 63%.

This alloy has a white color. The alloy used to constitute the peripheral crown has the following composition, expressed by weight: nickel: 5.5% zinc: 24.5% copper: 70%.

This alloy has "a yellow color.

This part can be easily recycled and reused.

This example shows that the method according to the present invention can be implemented for the manufacture of a relatively inexpensive part. We know that nickel is an expensive element compared to copper and zinc.

It may therefore be advantageous, from an economic point of view, to produce a two-tone part comprising as little nickel as possible.

Examination of the copper-nickel-zinc state diagram given in the single figure shows that a minimum nickel content of approximately 8% and a minimum zinc content of approximately 17% is required to obtain a colored alloy. white.

The peripheral crown cannot be made of a nickel-free alloy for reasons of corrosion resistance. An alloy comprising 5.5% nickel and 24.5% zinc has satisfactory corrosion resistance. The part thus obtained in Example 3 has an average nickel content of 8 to 8.5%, for a crown weight substantially identical to the weight of the core, which demonstrates that the process according to the invention makes it possible to manufacture two-tone pieces economically.

Example 4

180 kg of a Cu-Ni 75/25 alloy are transformed by fusion with the addition of 220 kg of copper and 100 kg of zinc, to obtain:

500 kg of a white alloy, the composition of which, expressed by weight, is as follows: nickel: 9% zinc: 20% copper: 71%; and

300 kg of a Cu-Ni 75/25 alloy are transformed by fusion with the addition of 100 kg of copper and 100 kg of zinc, to obtain: - 500 kg of a yellow alloy whose composition, expressed by weight, is as follows: nickel: 15% zinc: 20% copper: 65%.

Using these alloys, it is possible to manufacture a ton of two-tone parts, each consisting of an outer crown of yellow color weighing approximately 3.2 g and a heart of white color of approximately the same weight.

Claims

1. Method for the production of multicolored metal parts such as in particular coins, medals or tokens, characterized in that it consists in assembling, in a manner known per se, at least two parts made of metal alloys of the same qualitative composition, but different in their quantitative composition, the nature of these alloys and their quantitative composition being chosen so as to obtain a color contrast.

2. Method according to claim 1, characterized in that the aforementioned alloys are copper-nickel-zinc alloys belonging to the family of nickel silver.

3. Method according to claim 1 or 2 for the manufacture of a two-tone part comprising a central core made of an alloy comprising, expressed by weight 25% nickel, 15% zinc and 60% copper, and a peripheral crown consisting of an alloy comprising, expressed by weight, 7.5% nickel, 25% zinc and 67.5% copper.

4. Method according to claim 1 or 2 for the manufacture of a two-tone piece comprising a central core made of an alloy comprising, expressed by weight 25% nickel, 15% zinc and 60% copper, and a peripheral crown consisting of an alloy comprising, expressed by weight, 7.5% nickel, 5% zinc and 87.5% copper.

5. Method according to claim 1 or 2, for the manufacture of a two-color piece comprising a central core made of an alloy comprising, expressed by weight 11% nickel, 26% zinc and 63% copper, and a crown device made of an alloy comprising, expressed by weight 5.5% of nickel, 24.5% of zinc and 70% of copper.

6. multicolored recyclable metal part, such as in particular a coin, a medal or a token, of the type comprising at least two parts of different color, characterized in that said parts are made of metal alloys of the same qualitative composition, but different in their quantitative composition, the nature of these alloys and their quantitative composition being such that they make it possible to obtain a color contrast.

7. Part according to claim 6, characterized in that the aforementioned alloys are copper-nickel-zinc alloys belonging to the family of nickel silver.

8. Part according to claim 6 or 7, characterized in that it is two-tone and comprises a central core consisting of an alloy comprising, expressed by weight, 25% of nickel, 15% of zinc and 60% of copper, and a peripheral crown made of an alloy comprising, expressed by weight, 7.5% nickel, 25% zinc and 67.5% copper.

9. Part according to claim 6 or 7, characterized in that it is two-tone and comprises a central core consisting of an alloy comprising, expressed by weight 25% nickel, 15% zinc and 60% copper, and a peripheral crown made of an alloy comprising, expressed by weight, 7.5% nickel, 5% zinc and 87.5% copper.

10. Part according to claim 6 or 7, characterized in that it is two-tone and comprises a central core consisting of an alloy comprising, expressed by weight 11% nickel, 26% zinc and 63% copper, and a peripheral ring made of an alloy comprising, expressed by weight 5.5% of nickel, 24.5% of zinc and 70% of copper.

11. Process for the recycling and reuse of alloys based on copper and nickel, such as in particular the Cu-Ni alloy 75/25, characterized in that it consists in transforming said alloy into a nickel silver alloy, by example by fusion, by adding previously calculated quantities of copper and zinc.

12. Use of nickel-silver Cu-Ni-Zn alloys for the manufacture of multicolored metal parts, such as coins, medals and tokens in particular.