KR20010052152A - Titanium alloy watch part - Google Patents

Abstract

The present invention has a composition of 5.5 to 6.75% by weight aluminum, 3.5 to 4.5% by weight vanadium, 0.05% by weight up to nitrogen, 0.1% by weight carbon, 0.01% by weight hydrogen, 0.4% by weight iron, 0.2% by weight oxygen, A watch component made of an alloy having a maximum of 0.1% by weight, a maximum of 0.5% by weight in total and a residual amount of titanium, respectively. This alloy allows watch parts to be processed, polished and polished with conventional tools.

Description

Titanium alloy watch part {Titanium alloy watch part}

Among conventional materials such as gold and steel, titanium has occupied an important place in the production of watch cases in recent years. It is considerably cheaper than gold in price and has the advantage of being very well tolerated by the skin compared to steel and not causing nickel allergy. Furthermore, its commercial success has been facilitated by a matte finish that can easily prove the same as it has begun to mania, and this material is more commonly associated with high quality watches or other products.

The present invention begins with the observation that this very special surface appearance of titanium, which is commonly used for watchmaking, will probably not always be advantageous from this tendency. Thus, the aesthetic restrictions imposed by this material are unlikely to always be accepted by large customers.

Attempts have been made in the past to modify the appearance of watches made of titanium, for example by coloring or by plating special alloys of titanium on other materials. However, plating adds to the cost of the part and further makes the part susceptible to shock and deep scratches.

The present invention relates to a watch component of titanium alloy according to the preamble of claim 1.

It is therefore an object of the present invention to provide a watch component made of titanium, which has a different appearance than the conventional titanium parts and can occupy other commercial areas.

This object is achieved according to the invention by a watch component made of a titanium alloy which is unprecedented in watchmaking.

In particular, this object is achieved by relying on an alloy group containing 75% or more of titanium hardened by a work heat treatment and having a mechanical strength of preferably 750 MPa or more, preferably close to 1000 MPa. These special alloys have the advantage of being polished over a large surface.

There has already been a test to polish watch parts made of titanium. However, conventionally used titanium alloys do not allow large parts such as case bands or bracelets to be completely polished. The surface condition obtained was similar to orange peels, made from solid titanium with only small parts such as bezels or small parts of larger parts polished.

The orange peel appearance is particularly attributable to the presence of numerous two-phase alloy structures (e.g., α and β phases) that have different hardness and thus are unlikely to give the same glossy finish. EP 0 416 929 describes a method for manufacturing a watch case made of a titanium alloy in which an already processed part is heated to a temperature above the transformation point, i.e., above about 780 ° C and cooled to make it a martensite phase. have. An aging operation is then required before the watch case is polished. This method involves many separate tasks and is therefore difficult to perform on an industrial scale.

However, tests have shown that the grain size of the alloy plays a decisive role in the gloss quality obtained. Since ordinary titanium alloys consist of particles having a size of 150 to 200 mu m, the difference in gloss between neighboring particles is very noticeable.

The optimum gloss quality can thus be obtained by refining the microstructure of the alloy, ie by reducing the particle size that makes the alloy of the watch part. According to the present invention, such refining is obtained by working heat treatment of the watch parts.

The invention will be further understood by reference to the examples given in the following description without the figures required to describe them.

The invention is used in the manufacture of certain watch components, in particular casebands, backs of watch cases, bezels, bracelets and at least certain elements of spread buckles and clasps. The present invention is thus used in any external part of a pocket watch or wrist watch.

According to the invention, at least one of these parts is made of a medium or high strength solid titanium alloy, ie a titanium alloy having a mechanical strength of at least 750 MPa, preferably close to 1000 MPa.

These alloys have not been conventionally considered for use in the manufacture of watches because of the prejudiced bias, that is, the belief of numerous watchmakers that these materials cannot be properly processed and stamped. For that reason, titanium alloys with low mechanical strength have always been used in the manufacture of watches. The mechanical properties of these alloys were sufficient for the use of watchmaking, and there was no motivation to use fictitious alloys that were much more difficult to work with.

Nevertheless, despite the prevailing opinion, the tests performed gave unexpected results and showed that watch parts can be manufactured from these alloys with modern cutting and stamping tools such as those used to machine stainless steel. Furthermore, acid engraving is also possible. Thus, these tests showed that, despite all the existing biases, those skilled in the field of manufacturing watchmaking parts can process these new alloys using conventional tools after several routine operations. For example, these new alloys can be processed by carefully selecting the machining tool from existing machining tools and reducing the machining speed.

By subjecting these alloys to a work heat treatment, it has been found that it is possible to obtain materials that can be polished to significantly reduce the α and β particle sizes of the alloy and thus give the component a mirror finish. This gloss is unique in the manufacture of watches for titanium watches. Thus, the beneficial properties of this material, in particular its antiallergic properties, can be extended to the field of watches where the use of other metals is more desirable for aesthetic reasons.

The work heat treatment preferably consists of heating the alloy to a temperature below β transformation point (780 ° C.) during the deformation operation of the initial part. Preferably, the work heat treatment consists of stamping the heated part at a temperature of 600 to 750 ° C., preferably 600 to 700 ° C. Tests have shown that effective refining of the alloy microstructure is obtained when the alloy undergoes pressure or significant deformation simultaneously and is heated to a temperature slightly below the β transformation point. Various mechanisms, such as dynamic recrystallization, can be used to refine the microstructures. Particle sizes of less than 5 μm, almost similar to 1 μm, can be obtained through appropriate selection of heating temperature and strain pressure applied.

The alloy used can also be oxidized and anodized by electrolysis to achieve various color effects.

The hardening and stamping of the parts are therefore carried out in a single operation: no heating, cooling or aging work is required afterwards. This method is therefore particularly advantageous for the transition compared to the conventional method.

Suitable medium and high strength titanium alloy groups for this gloss particularly include:

Binary Alloy: Ti 8Mn

Three-Component Alloy: Ti 6Al 4V, Ti 7Al 4Mo

Four-Component Alloy: Ti 8Al 1Mo 1V, Ti 10V 2Fe 3Al

Ti 6Al 6V 2Sn, Ti 4Al 3Mo 1V

Ti 10V 2Fe 3Al

Alloys of five or more elements: Ti 6 Al 2Sn 4Zr 6Mo,

Ti 5Al 2Sn 4Zr 4Mo 4Cr, Ti 6Al 2Sn 2Zr 2Mo 2Cr

Ti 15V 3Cr 3Al 3Sn

(The numbers represent the weight percent in the composition).

In general, these are two-phase α + β titanium alloys that provide an optimal compromise between ductility and mechanical strength. However, almost no single phase α alloy or β structure alloy is excluded. These biphasic alloys can be refined and cured by suitable work heat treatment.

In titanium alloys, aluminum has a property of stabilizing α phase which is stable at temperatures up to 880 ° C. Vanadium stabilizes the β phase, which is usually stable at temperatures above 880 ° C. Testing has shown that alloy Ti 6Al 4V is optimal for the manufacture of mirror-polished titanium watchmaking parts. The composition of this alloy can vary as follows:

5.5 to 6.75 wt% aluminum, 3.5 to 4.5 wt% vanadium, 0.05 wt% nitrogen, 0.1 wt% carbon, 0.15 wt% hydrogen, 0.4 wt% iron, 0.2 wt% oxygen, 0.1 wt% each of various elements %, Total up to 0.5% by weight and titanium residues.

Advantageously, the watchband's caseband, backside, bezel, spread buckle, clasp, and / or bracelet can be made of one of these alloys. Nevertheless, it is also possible to combine the use of these alloys for a particular element or for a particular part of a particular element and the use of different materials for other elements. In particular, the combination of the use of medium or large mechanical strength titanium for certain parts, i.e. the parts visible while wearing watches, and the use of low mechanical strength titanium for less visible parts such as spread buckle It is possible.

Claims (17)

Curing an alloy containing at least 75% titanium and having a mechanical strength of at least 750 MPa during the work heat treatment step; and A method of making a watch component made of a solid titanium alloy, comprising polishing a visible outer surface of the part. The method of manufacturing a watch component according to claim 1, wherein the work heat treatment is obtained by heating the alloy below the β transformation point during the deformation operation of the initial part. The method of manufacturing a watch component according to claim 1 or 2, wherein the work heat treatment is obtained by heating the alloy to a temperature of 600 to 750 ° C during stamping of the watch component. 4. A method for producing a watch component according to any one of claims 1 to 3, wherein the heating time, heating temperature and applied pressure are optimized to obtain an alloy particle size of less than 5 mu m. The method of manufacturing a watch component according to any one of claims 1 to 4, which does not include a quenching step. The method for manufacturing a watch component according to any one of claims 1 to 5, wherein the alloy is a two-phase α + β type alloy. The composition of any one of claims 1 to 6, wherein the composition of the alloy is 5.5 to 6.75% by weight aluminum, 3.5 to 4.5% by weight vanadium, 0.05% by weight nitrogen, 0.1% by weight carbon, 0.015% by weight hydrogen, Method for producing a watch component, characterized in that up to 0.4% by weight of iron, up to 0.2% by weight of oxygen, up to 0.1% by weight of each of the various elements, up to 0.5% by weight in total, and titanium. A watch component made of a solid alloy containing at least 75% titanium, wherein the alloy is cured during the work heat treatment step, the mechanical strength is at least 750 MPa, and at least the visible outer surface of the part is polished. The watch component according to any one of claims 1 to 8, wherein the alloy has a particle size of less than 5 mu m. The watch component according to claim 8 or 9, wherein the alloy is a two-phase α + β type alloy. The composition of any one of claims 1 to 10, wherein the alloy has a composition of 5.5 to 6.75 weight percent aluminum, 3.5 to 4.5 weight percent vanadium, 0.05 weight percent nitrogen, up to 0.1 weight percent carbon, 0.015 weight percent hydrogen, A watch component characterized in that up to 0.4% by weight of iron, up to 0.2% by weight of oxygen, up to 0.1% by weight of various elements, up to 0.5% by weight in total, and titanium. 12. The watch component of claim 1, wherein only the visible outer surface consists of a polished case band. The watch component of claim 8, wherein the watch component comprises a bezel, which is a polished visible outer surface. The watch component of claim 8, wherein the watch component is comprised of a bracelet, which is at least a polished visible outer surface. A watch comprising at least a case band according to claim 12 and a bracelet according to claim 14. The watch according to claim 1, further comprising one or more other parts made of titanium or titanium alloy whose mechanical strength is less than the mechanical strength of the caseband. 17. The watch according to any one of the preceding claims, wherein at least one element of the spread buckle is made of titanium or titanium alloy whose mechanical strength is less than the mechanical strength of the caseband.