The present invention relates to the field of mechanisms driven by a mainspring, in particular in the horology field. It more particularly relates to a barrel spring formed from a monolithic ribbon of metallic glass.
In the present application, the term “spring” must be interpreted as a ribbon made from a material having elastic properties and which comprises a fastening portion at each of its ends, allowing the ribbon to store and release mechanical energy.
Known from document CH 698962 is the possibility of making monolithic ribbons intended to be used as barrel springs from metallic glass. The term “metallic glass” refers to an amorphous metal alloy or an amorphous metal, the solid object of which is obtained from the molten alloy. The intrinsic properties of metallic glasses give them very good elastic aptitudes, excellent ductility, great mechanical strength, and optimized fatigue behavior. This type of material is therefore particularly well-suited to applications in barrel springs, in particular for timepieces.
The aforementioned document also proposes a method for producing such a ribbon of metallic glass, in which a strip of metallic glass is given a shape as close as possible to a predetermined shape, using a so-called Planar Flow Casting technique, before relaxing the strip to set its shape by heating it, before ultimately cooling it. It is mentioned that, in an additional step, a slip-spring may be assembled to the last coil of the spring to allow it to be mounted in a barrel drum. The assembly of the inner coil of the blade on the barrel arbor is not mentioned. Another additional step must be applied to the ribbon to allow it to be connected to a barrel arbor. Thus, this document only provides for producing a monolithic ribbon of metallic glass and not, strictly speaking, producing a spring from metallic glass, since fastening portions must be added or formed on the ribbon obtained using the method described in the patent application.
The present invention proposes to go further in the use of metallic glass to produce barrel springs, including in the method to achieve that aim.
In particular, the present invention proposes to produce a barrel spring made from a monolithic ribbon of metallic glass comprising a fastening portion at each of its ends, characterized in that said spring, i.e. the ribbon and the fastening portions situated at the ends thereof, is monolithic and obtained directly by a molding operation.
According to another aspect, the invention relates to a barrel spring formed from a monolithic ribbon of metallic glass, characterized in that the ribbon comprises at least one functional portion integral with the ribbon to perform at least one additional function in addition to the spring function. “Additional function in addition to the spring function” refers to a function other than the storage or release of mechanical energy or the fastening functions of the ribbon, which are considered inherent to the spring function.
Various additional functions may also be produced, as mentioned in the claims. These functions may potentially be combined with one another.
Other details of the invention will appear more clearly upon reading the following description, proposed in reference to the appended drawing, in which
The figures propose barrel springs made from metallic glass. Aside from the normal function of a barrel spring, i.e. the spring function making it possible to store energy owing to a ribbon made from elastic material, the ends of which are provided with fastening portions, the barrel springs according to the invention incorporate an additional function. In other words, in a monolithic embodiment, the barrel springs are configured so as to have a functional portion, making it possible to perform additional function. Thus, “additional function in addition to the spring function” refers to a function other than the energy storage functions, the fastening portions of the ribbon participating in the spring function.
This possibility is in particular offered by a method that is one aspect of the invention. In fact, one of the interesting ideas that made it possible to arrive at the invention is to use a completely different manufacturing method from what is proposed by the state of the art, particularly the aforementioned document, to obtain a barrel spring made from metallic glass.
This method first comprises producing a mold having the shape of the part one wishes to obtain. This mold is advantageously made from silicon using deep etching techniques. The mold thus withstands the melting temperatures of the metallic glasses well, while making it possible to produce complex shapes very precisely. These techniques are well known by those skilled in the art and do not need to be described thoroughly.
Once the mold is obtained, metallic glass can then be poured into the mold, then the glass is cooled so as to preserve an amorphous state, and the part can be stripped. For pouring, the glass may be in the liquid phase or paste phase. The precision of the molds produced means that the obtained parts do not have to be touched up. Furthermore, for stripping, the mold can be dissolved, which allows it to be eliminated, irrespective of the complexity of the part produced, without destroying the latter. It will be noted that the springs could also be molded in a copper mold.
Using this method, it is thus possible to produce various barrel springs 10, incorporating an additional function. First, as particularly shown in
In
The spring illustrated in
Lastly, the spring proposed in
As an example, a barrel spring of the type proposed in
The functions proposed above may in some cases be combined with one another. The figures are only non-limiting examples of the invention, the essence of which is defined in the claims.
Number | Date | Country | Kind |
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10164172.8 | May 2010 | EP | regional |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP11/58380 | 5/23/2011 | WO | 00 | 11/27/2012 |