Classifications

• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B19/00—Indicating the time by visual means
  • G04B19/04—Hands; Discs with a single mark or the like
  • G04B19/042—Construction and manufacture of the hands; arrangements for increasing reading accuracy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
  • B22D17/007—Semi-solid pressure die casting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D25/00—Special casting characterised by the nature of the product
  • B22D25/02—Special casting characterised by the nature of the product by its peculiarity of shape; of works of art
  • B22D25/026—Casting jewelry articles
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C45/00—Amorphous alloys
  • C22C45/10—Amorphous alloys with molybdenum, tungsten, niobium, tantalum, titanium, or zirconium or Hf as the major constituent
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B19/00—Indicating the time by visual means
  • G04B19/04—Hands; Discs with a single mark or the like
• • G—PHYSICS
  • G04—HOROLOGY
  • G04D—APPARATUS OR TOOLS SPECIALLY DESIGNED FOR MAKING OR MAINTAINING CLOCKS OR WATCHES
  • G04D3/00—Watchmakers' or watch-repairers' machines or tools for working materials
  • G04D3/0002—Watchmakers' or watch-repairers' machines or tools for working materials for mechanical working other than with a lathe
  • G04D3/0043—Watchmakers' or watch-repairers' machines or tools for working materials for mechanical working other than with a lathe for components of the time-indicating mechanisms
  • G04D3/0046—Watchmakers' or watch-repairers' machines or tools for working materials for mechanical working other than with a lathe for components of the time-indicating mechanisms for hands

Definitions

• the present invention relates to a timepiece needle, said needle being pivotally mounted about an axis so as to be able to indicate information.
• the technical field of the invention is the technical field of fine mechanics.
• timepieces include needles. These needles consist of a beam whose length is much greater than the width, itself much larger than the thickness. These needles include an orifice to be driven on an axis so as to be pivotally mounted. In order to have fine and strong needles, it is planned to make them in crystalline metal such as steel, brass, gold or even silicon or ceramic. These needles can be machined or cut by laser or water jet from a plate. They can also be molded, sintered or made by growth or deposition of material. These needles are then used for example to indicate hours, minutes and seconds but also when performing certain functions such as chronograph functions or date functions.
• the needle also undergoes acceleration constraints. These constraints can be due, in the first place, to the movement controlled by the watch movement. This movement is linked to the display of the time or to a function of said timepiece such as the chronograph function, and can be retrograde. However, for a retrograde display or when using the chronograph function, an instantaneous reset of the hands is performed. This reset consists of a sudden return of the needle to its initial position. During this resetting operation, the acceleration of the needle can reach 1 ⁇ 1 0 6 rad ⁇ s 2. Such acceleration involves a high stress applied to the needle during acceleration as well as during deceleration and stopping of the needle.
• the constraints related to acceleration can be due to a shock applied to the watch. Indeed, when, for example, the watch falls, it undergoes an acceleration. The energy stored during this fall is transmitted to the hands during the contact of said watch with the ground. These shocks can then deform the needle or unbalance can then cause problems during the movement of the needle.
• each material is characterized by its Young's modulus E also called modulus of elasticity (generally expressed in GPa), characterizing its resistance to deformation.
• Each material is also characterized by its elastic limit ⁇ ⁇ (generally expressed in GPa) which represents the stress beyond which the material deforms plastically. It is then possible, for given dimensions, to compare the materials by establishing for each the ratio of their elastic limit on their Young's modulus ⁇ ⁇ / ⁇ , said ratio being representative of the elastic deformation of each material. Thus, the higher the ratio, the greater the elastic deformation of the material.
• the Young's modulus E is equal to 130 GPa and the elastic limit ⁇ ⁇ is equal to 1 GPa, which gives a ratio ⁇ ⁇ / ⁇ of the order of 0.007 i.e. low.
• Needles of metal or crystalline alloy have, therefore, limited elastic deformation. Consequently, when returning to zero or shock, the stresses applied to said needles can be so high that the needles deform plastically, that is to say they twist. This deformation then poses a problem of readability and reliability of the information.
• the invention aims to overcome the disadvantages of the prior art by proposing to provide a metal needle for sudden acceleration that does not deform during its movement to have a precise readability and significant durability.
• the invention relates to the aforementioned needle which is characterized in that it is made of a totally amorphous metal alloy comprising at least one metal element selected from the group consisting of gold, platinum, palladium, rhenium, ruthenium, rhodium, silver, iridium or osmium.
• a first advantage of the present invention is to allow the realization of precious metal needles that can withstand sudden shocks or accelerations. It therefore becomes possible to make needles of precious materials having dimensions similar to those of non-precious materials or precious crystalline materials, without the risk that they will deform during a strong acceleration.
• precious amorphous metals have more interesting elastic characteristics than their crystalline counterparts.
• the elastic limit ⁇ ⁇ is increased to increase the ratio ⁇ ⁇ / ⁇ so that the material sees the stress beyond which it does not resume its initial shape increase.
• Another advantage of the present invention is to allow great ease in shaping allowing the development of complicated shapes with greater precision.
• the amorphous precious metals have the particular characteristic of softening while remaining amorphous for a certain time in a given temperature range [Tg - Tx] specific to each alloy (with Tx: crystallization temperature and Tg: glass transition temperature). It is thus possible to shape them under a relatively low stress and at a low temperature then allowing the use of a simplified process.
• the use of such a material also makes it possible to reproduce fine geometries very precisely because the viscosity of the alloy decreases sharply as a function of the temperature in the temperature range [Tg-Tx] and the alloy thus allies the details of a negative.
• the term "negative” is understood to mean a mold which has a hollow profile complementary to that of the desired needle. This then makes it possible to produce a needle in three dimensions, which the techniques of the prior art can not or hardly allow.
• said needle is fixed on its axis by means of a barrel.
• said needle and said barrel form a single piece.
• said needle is arranged to be driven by a retrograde movement.
• the invention also proposes to provide a chronograph comprising at least one needle according to the present invention.
• the invention also proposes to provide a use of the needle according to the present invention for an application in which said needle undergoes, at a given moment, an acceleration of at least 250,000 rad / s- 2 and preferably an acceleration of the order of 1 .10 6 rad / s "2 .
• the invention also proposes to provide a method for producing the needle according to the present invention, said method comprising the following steps:
• step c) comprises the following steps:
• step c) comprises the following steps:
• the method comprises, before the step of cooling said material, the step of removing the excess material.
• said needle is fixed on its axis by means of a barrel and in that said needle and said barrel are one and the same piece produced during the c) shaping step .
• said needle is fixed on its axis by means of a barrel and in that said needle is fixed to said barrel during step c) shaping.
• said at least one metal element of the precious type is chosen from the group formed by gold, platinum, palladium, rhenium, ruthenium, rhodium, silver, iridium or osmium ..
• FIG. 1 schematically shows a chronograph function timepiece
• FIG. 5 represents the deformation curves for a crystalline material and for an amorphous material
• FIGS. 6 to 9 schematically represent the method according to the present invention.
• FIGS. 10 to 14 schematically represent a variant of the method according to the present invention.
• FIG. 15 shows a top view of a needle variant according to the present invention.
• FIG. 1 shows a timepiece 1 comprising several needles 2 pointing to information on the dial of said timepiece.
• These needles 2 may be the hands indicating the hours, minutes or seconds. They may be driven by a continuous or retrograde movement, said displacement may include sudden acceleration.
• sudden acceleration a sudden acceleration, predictable or not and occurring during a limited time and whose value is very high, said acceleration succeeding a displacement having a null acceleration, constant or weak.
• the sudden accelerations that can be supported are at least 250,000 rad.s -2 and preferably 1 .10 6 rad.s -2 .
• These needles 2 can also be chronograph or date hand 2 or other.
• Such a needle 2 shown in Figure 2 consists of a beam 3 whose length is much greater than the width of the beam 3, this width is itself much larger than the thickness.
• a first end 31 of the beam serves to point information. This first end 31 is preferably the thinnest end.
• An orifice 4 is provided to allow the needle to be driven on its axis 10.
• This orifice 4 is arranged near the second end 32 of the beam forming the needle 2.
• This second end 32 may be arranged so as to serve as an unbalance to ensure a good balance of the needle 2 during its movement. It is also conceivable for the second end 32 to be arranged, as can be seen in FIG. 1, to be circular and to include the orifice 4 making it possible to drive it on its axis 10.
• the needle 2 is mounted on an axis 10 being directly driven on said axis 10 as visible in Figure 2 or being reported on a barrel 5 itself driven on the axis 10 as shown in Figure 4. It is also possible that the barrel 5 comes directly from material with the needle 2 as visible in Figure 3.
• At least one of the needles 2 is made of an at least partially amorphous material comprising at least one metal element.
• This metal element may be valuable such as gold, platinum, palladium, rhenium, ruthenium, rhodium, silver, iridium or osmium. It will be understood by at least partially amorphous material that the material is capable of solidifying at least partially in the amorphous phase, that is to say that it is capable of losing at least locally all of its crystalline structure.
• the maximum energy that can be stored elastically is calculated as being the ratio between the elastic limit ⁇ ⁇ squared and the module Young E. Gold, with a higher elastic limit of a factor substantially equal to two, the energy that the amorphous metal can store elastically is therefore higher by a factor substantially equal to four. This allows the amorphous metals to be able to undergo a greater stress before reaching the elastic limit ⁇ ⁇ .
• a needle 2 of amorphous metal makes it possible, first of all, to improve the reliability of the latter with respect to its crystalline metal equivalent.
• the stress applied to the needle 2 is related to the moment of inertia of the needle 2, which is a function of mass and length. Therefore, the longer a needle is or the greater the mass at the end of the needle 2 and the higher the moment of inertia of the needle 2 will be high.
• the kinetic energy accumulated during the displacement of the needle 2 following a reset or shock is dependent on the moment of inertia. This kinetic energy determines the stress applied to the needle 2 during the return movement to zero or during the impact. High kinetic energy leads to high stress and therefore a risk of significant deformation.
• a material can also be characterized by its specific resistance which is the ratio of the elastic limit to the density.
• An amorphous metal has a higher specific resistance than a crystalline metal because, on the one hand, for the same type of alloy, the amorphous metal has an elastic limit which is about twice as high and, on the other hand, for In a given composition, the amorphous structure has a density which is about 10% less than that of the crystalline structure.
• a needle of amorphous metal alloy or amorphous metal will be lighter than a needle of the same dimensions made of a metal alloy likewise composition but of crystalline structure.
• the moment of inertia will therefore be lower for the amorphous metal needle, the moment of inertia being linked to the mass.
• the kinetic energy and therefore the stress applied to the amorphous metal needle will be lower so that the needle will be able to withstand a higher stress before plastically deforming.
• This density advantage combined with the ability of amorphous metals to undergo a higher stress before plastically deforming enables the use of amorphous precious metal alloys.
• the elastic limit of an amorphous precious metal alloy is greater by a ratio of about two to its crystalline equivalent.
• This amorphous precious metal alloy can therefore withstand a higher stress than its crystalline equivalent before plastically deforming.
• the stress is related to the kinetic energy which is itself related to the moment of inertia depending on the mass and the length. Consequently, since precious or non-amorphous metal alloys have a lower density than their crystalline equivalents, their displacements have a lower kinetic energy and therefore a lower stress.
• a needle made of an amorphous precious metal alloy of the same dimensions as a needle made of a crystalline precious metal alloy will have a lower mass and its displacement will generate a lower stress.
• the stress is lower and the maximum stress supported is higher, the use of amorphous precious metal alloys to make needles to undergo strong and sudden accelerations are possible contrary to the prejudices of the skilled person.
• the characteristics of the amorphous metal make it possible, secondly, to envisage more varied shapes of needles 2. Indeed, the moment of inertia is used to know the kinetic energy of the needle and the stress it will undergo when returning to zero. This moment of inertia is dependent on the mass and the length of the needle 2. These parameters are therefore calculated to limit the risk of plastic deformation of the needle 2.
• the mass and length of the needle 2 can be increased without risking plastic deformation. More particularly, the mass at the first end of the needle 2 can be increased, allowing access to possibilities of larger needle shapes 2. It is then possible to provide for this first end to comprise, for example, a zone with larger dimensions for applying a luminescent material, or for the second hand of the chronograph to take the form of a Breguet-type needle 2. It is also possible that the mass at the second end 32, which can serve as unbalance, be increased.
• the characteristics of the amorphous metal make it possible to increase the dimensions of the needles 2, they also make it possible to make needles 2 with smaller dimensions. Indeed, at equivalent stress, the needle 2 may be of shorter length and / or less mass without plastically deforming, this being the consequence of a higher elastic limit This reduction in dimensions can also be applied to the unbalance of the needle 2 serving for the balance of said needle 2.
• the precious amorphous metal or not has the double advantage of allowing to increase or decrease the size of the needles 2 without increasing the risk of plastic deformation.
• the reduction in the size and / or mass of the needle can be done by arranging recesses 1 1 through or not through the needles 2 as visible in Figure 15. These recesses 1 1 can reduce, by removal of material , the mass of the needles 2 and thus reduce the moment of inertia while providing an interesting visual effect.
• To make a needle 2 amorphous metal several methods are possible.
• amorphous metal is thus previously arranged in the form of thin plates. These thin plates are then stamped in press or cut by water jet or laser.
• This preform 7 is obtained by melting the metal elements constituting the amorphous alloy in a furnace. This fusion is made under controlled atmosphere with the purpose of obtaining a contamination of the alloy in oxygen as low as possible. Once these elements are melted, they are cast as a semi-finished product, such as for example a blade of dimension close to the needle, and then rapidly cooled in order to maintain the at least partially amorphous state or phase.
• the hot forming is performed in order to obtain a final piece. This hot forming is performed by pressing in a temperature range between its glass transition temperature Tg and its crystallization temperature Tx for a predetermined time to maintain a totally or partially amorphous structure. This is done in order to maintain the characteristic elastic properties of the amorphous precious metals.
• the different stages of definitive shaping of the needle 2 are then:
• Hot forming makes it possible to simplify the production of said needle 2, in particular to make the recesses 1 1 of the needle represented in FIG.
• the dies 8 forming the mold are then arranged to form the negative of the needle 2 and its integrated gun 5. Steps a) to g) are then performed to form said needle 2.
• This arrangement of the needle 2 and its barrel 5 in one piece makes it possible to have no problem of fixing between said needle 2 and its barrel 5.
• the barrel 5 shown in FIG. 4, consists of a cylindrical piece whose internal diameter d is equal to the diameter of the axis 10 on which the cannon 5 is hunted.
• the barrel 5 comprises an outer diameter D greater than the inner diameter d, the outside diameter D may not be uniform over the entire barrel 5.
• the profile of this barrel 5 comprises an annular recess 6 in which needle 2 is placed. This recess, whose diameter is between the inner and outer diameters, allows an axial retention of the needle 2.
• the barrel 5 is placed between the dies 8 in which the needle 2 will be made as visible in Figure 1 1. Steps a) to g) previously described are then made and shown in Figures 12, 13 and 14.
• the needle 2 is overmolded directly on the barrel 5 and is therefore directly attached to the barrel 5.
• the wall of the annular recess comprises reliefs or other means for improving the maintenance of the needle 2 in the barrel 5 and in particular the angular support.
• the needle 2 or the part forming the barrel 5 and the needle 2 can be made by casting or injection. This process involves casting the alloy obtained by melting the metal elements in a mold having the shape of the final piece. Once the mold is filled, it is cooled rapidly to a temperature below T g in order to avoid crystallization of the alloy and thus obtain a needle 2 of amorphous or partially amorphous precious metal.

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• Engineering & Computer Science (AREA)
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• General Physics & Mathematics (AREA)
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• Organic Chemistry (AREA)
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• 2010
  • 2010-06-22 EP EP10166844A patent/EP2400353A1/de not_active Withdrawn
• 2011
  • 2011-06-21 WO PCT/EP2011/060282 patent/WO2011161077A1/fr active Application Filing
  • 2011-06-21 JP JP2013515847A patent/JP5876878B2/ja not_active Expired - Fee Related
  • 2011-06-21 CN CN2011800407188A patent/CN103097967A/zh active Pending
  • 2011-06-21 CN CN201610838594.2A patent/CN107015472A/zh not_active Withdrawn
  • 2011-06-21 US US13/806,368 patent/US9329572B2/en not_active Expired - Fee Related
  • 2011-06-21 EP EP11727681.6A patent/EP2585879A1/de not_active Ceased

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