阅读说明：本技术 着色的热补偿螺旋弹簧及其制造方法 (Colored thermally compensated coil spring and method of making same ) 是由 P·卡森 A·甘德尔曼 A·科斯塔蒂诺夫 于 2019-08-07 设计创作，主要内容包括：本发明涉及制造热补偿和着色螺旋弹簧(1)的方法,其包括以下步骤：-在芯部(2)的至少一个表面(2a,2c)和芯部(2)的至少一个其它表面(2a,2b,2c,2d)上形成二氧化硅(3)的第一层,第一层的厚度等于用于实现热补偿所需厚度的一部分,-从芯部(2)的所述至少一个表面(2a,2c)去除第一层,-在芯部(2)的所述至少一个表面(2a,2c)上以及在芯部(2)的所述至少一个其它表面(2a,2b,2c,2d)上形成二氧化硅(3)的第二层,第二层的厚度等于用于实现热补偿所需厚度的剩余部分,该剩余部分小于或等于1μm,以便由于干涉效应而使芯部(2)的所述至少一个表面(2a,2b)具有颜色。(The invention relates to a method for producing a thermally compensated and colored helical spring (1), comprising the following steps: -forming a first layer of silica (3) on at least one surface (2a, 2c) of the core (2) and on at least one other surface (2a, 2b, 2c, 2d) of the core (2), the thickness of the first layer being equal to a portion of the thickness required for achieving the thermal compensation, -removing the first layer from said at least one surface (2a, 2c) of the core (2), -forming a second layer of silica (3) on said at least one surface (2a, 2c) of the core (2) and on said at least one other surface (2a, 2b, 2c, 2d) of the core (2), the thickness of the second layer being equal to the remaining portion of the thickness required for achieving the thermal compensation, the remaining portion being less than or equal to 1 μm, so as to cause, due to interference effects, said at least one surface (2a, 2b) has a color.)

1. A method of manufacturing a thermally compensated and coloured coil spring (1) for a timepiece component, said method comprising the following successive steps:

a) providing a helical spring (1) comprising a silicon core (2),

b) forming a first layer of silicon dioxide (3) on all the surfaces (2a, 2b, 2c, 2d) of the core (2) of the helical spring (1), the thickness of which is equal to a fraction of the thickness required for achieving the thermal compensation,

c) removing a first layer of silicon dioxide (3) from one surface (2a) of the core (2) designed to be coloured due to interference effects,

d) forming a second layer of silica (3) on said surface (2a) of the core (2) designed to be coloured due to interference effects and on other surfaces (2b, 2c, 2d) of the core (2) designed to ensure thermal compensation, the second layer of silica (3) having a predetermined thickness to achieve thermal compensation and also giving colour to said surface (2a) of the core (2) designed to be coloured due to interference effects.

2. Method according to claim 1, characterized in that the thickness of the second layer consisting of silicon dioxide (3) is adjusted to the desired color.

3. Method according to claim 1, characterized in that the first and second layer consisting of silicon dioxide (3) are formed in step b) and step d) by thermal oxidation.

4. The method according to claim 1, characterized in that step c) is performed by anisotropic engraving.

5. The method according to claim 1, further comprising step e) after step d): -depositing an electrically conductive layer (4) on all or part of at least one of said other surfaces (2a, 2b, 2c, 2d) of the core (2) designed to ensure thermal compensation.

6. Method according to claim 1, characterized in that a first and a second layer of silicon dioxide (3) are formed on all surfaces (2a, 2b, 2c, 2d) of the core (2), the first layer of silicon dioxide (3) being removed in step c) from the surfaces (2a, 2c) designed to be visible from the outside of the timepiece component.

7. A thermally compensated and coloured coil spring (1) for a timepiece component, the coil spring (1) comprising a silicon core (2), characterized in that the core (2) comprises:

-an interference layer made of silicon dioxide (3) on a surface (2a) designed to be assembled in a timepiece component and visible from the inside, the thickness of the interference layer being less than or equal to 1 μm, so that said at least one surface (2a, 2b) has a colour due to interference effects,

-a thermal compensation layer of silicon dioxide (3) on the other surfaces (2b, 2c, 2d), the thickness of the thermal compensation layer being greater than the thickness of the interference layer.

8. A helical spring (1) according to claim 7, wherein the core (2) comprises an interference layer on its upper surface (2a) and/or its lower surface (2c) and a thermal compensation layer on its two side surfaces (2b, 2 d).

9. A helical spring (1) according to claim 8, wherein the core (2) comprises a thermal compensation layer on both of its side surfaces (2b, 2d) and on its upper surface (2a) or its lower surface (2 c).

10. A coil spring (1) according to claim 7, characterized in that the coil spring (1) comprises an electrically conductive layer (4) covering all or part of said thermal compensation layer.

11. Timepiece component comprising a spiral spring (1) according to claim 1.

Technical Field

The present invention relates to a helical spring designed to provide an adjustment element of a mechanical watch.

Background

The value of a mechanical timepiece component is often related to the visibility of its parts. In this respect, hollow tables are highly appreciated by customers who can see the elements and main functions of the complex objects contained in these tables. The presentation of coil springs as a source of motion is particularly appreciated. Therefore, special attention needs to be paid to the aesthetic appearance of the part.

Coloring is one way to improve the aesthetic appearance of the part. Generally, coloring of the watch making parts may be by various methods for depositing the layers, such as PVD, ALD, electroplating processes, anodization, and the like. However, in the particular case of a helical spring, the deposition of such an aesthetic layer is incompatible with the specifications of the component, since it needs to be insensitive to the magnetic field and work with the pendulum to ensure a minimum difference in operation at different temperatures.

Disclosure of Invention

The subject of the invention is therefore a method for manufacturing a spiral spring that enables the visible surface of the spiral spring to be coloured and at the same time guarantees the specifications of the matrix (adjustment of the stiffness, protection against magnetism, compensation for thermal variations of the balance assembly, etc.).

For this purpose, the manufacturing method comprises forming a film on at least one surface of the core of the helical spring, so as to produce a colour on said surface due to an interference effect. The film is silicon dioxide (SiO)₂) The membrane, together with the other surfaces covered by the thicker silicon dioxide layer, contributes to the thermal compensation of the coil spring. By adjusting the thickness of the film, a large number of color choices can be obtained.

More specifically, the method includes adding a silicon dioxide layer in several steps:

-a first step: forming a first layer of silica on all surfaces of the core, the first layer having a thickness equal to a fraction of the thickness required to form the heat-compensating helical spring,

-a second step: the previously formed first layer of silicon dioxide is removed from the surface of the core which is designed to be coloured,

-a third step: a second layer of silicon dioxide is formed on the same surface as the first step, said second layer having a thickness equal to the remaining part of the desired thickness, which is less than or equal to 1 μm, in order to give the surface or surfaces a colour due to interference effects.

Preferably, the thermal compensation layer is formed on the side surface of the core and on the surface opposite to the surface designed to be visible inside the timepiece component.

This method has an advantage in that the formation of the colored layer has little influence on the manufacturing method of the coil spring and the function thereof. That is, in view of good performance at temperature, forming the thermal compensation layer on the side surface of the coil spring is not affected or is little affected by the present method.

Drawings

Further characteristics and advantages of the invention are given in the following description of a preferred embodiment, given by way of example and not by way of limitation, with reference to the accompanying drawings.

Fig. 1A is a perspective view of a coil spring according to the present invention. Fig. 1B is a transverse cross-sectional view of one turn of the coil spring of fig. 1A.

Fig. 2 schematically shows the different steps of the method according to the invention by means of a transverse cross-sectional view of one turn of the helical spring.

Detailed Description

A method of manufacturing a watch-making component capable of coloring a visible surface is described.

The invention is described herein by way of a simplified and non-limiting example of a coil spring 1 as shown in fig. 1A and 1B, and other components according to the invention may of course be manufactured.

To this end, the invention describes a thermally compensated helical spring having a single-crystal or polycrystalline silicon core 2 covered by a layer consisting of silicon dioxide 3, which makes it possible to adjust the variation of the thermoelastic coefficient of the helical spring in relation to the behaviour of the whole spiral balance (fig. 1B). According to the invention, at least one surface of the core designed to be visible after assembly inside the watch case comprises a layer of silica which is coloured by interference effects, this layer being referred to as interference layer. In the example shown, the face 2a is the upper face of a helical spring, designed to be visible through the glass of the watch case. In a variant, this may be a lower face 2c designed to be visible through the bottom of the watch. In another variant, the upper surface 2a and the lower surface 2c may comprise interference layers. The interference layer is in the form of a thin film having a thickness of 1 μm or less, and the thickness of the interference layer is adjusted to a desired color, the thickness range making it possible to obtain a more vivid color and thus be more easily visible. For example, table 1 shows examples of colors that can be obtained by interference with respect to film thickness.

TABLE 1

One or more surfaces not covered by the film are covered with a thermal compensation layer also made of silicon dioxide. Preferably, the helical spring comprises at least one thermal compensation layer on the side surfaces 2b, 2d of the core 2. More preferably, the core comprises a thermal compensation layer on three of the four surfaces of the portion, i.e. in the example illustrated on its side surfaces 2b, 2d and its lower surface 2 c. The thickness of the thermal compensation layer is different from the thickness of the interference layer, the thickness of the thermal compensation layer being greater than the thickness of the interference layer, more precisely greater than 1 μm. It should be clear, however, that the interference layer is partly related to the thermal compensation of the helical spring.

Further, the coil spring may include the conductive layer 4 on all or part of the surface including the thermal compensation layer. In the example shown, the continuous conductive layer 4 covers the lower surface 2c and partially covers the side surfaces 2b, 2 d. The conductive layer may be formed of a metal material such as gold, platinum, chromium, tantalum, titanium, rhodium, or palladium, and its thickness is preferably less than 50 nm. The conductive layer has an antistatic function and ensures partial sealing.

The method for manufacturing the thermally compensated and colored helical spring is partially illustrated in fig. 2 by a cross-sectional view of one turn of the helical spring. In this figure, the different steps performed during the growth of silicon dioxide are shown. Previously, a coil spring having a silicon core could be obtained from a silicon chip (wafer method). In a known manner, the chemical attack can be carried out, for example, by a wet process, a dry machining process by means of plasma or by Reactive Ion Etching (RIE) using a suitable mask for the desired coil profile.

The present invention includes replacing the conventional oxidation process designed to form the thermal compensation layer with a series of sequences as follows. The method is described below for a core 2, wherein the core 2 comprises a compensation layer on its side surfaces 2b, 2d and its lower surface 2c, and an interference layer on its upper surface 2 a.

Referring to fig. 2a, the first step consists in growing on the silicon core 2a layer consisting of silicon dioxide 3, the thickness of which is a fraction of the thickness required to obtain thermal compensation. This step can be performed, for example, by thermal oxidation. In a second step, shown in fig. 2b, the oxide layer grown on the upper surface 2a is completely removed. The oxide layer can be removed by engraving (engraving). The engraving is anisotropic, i.e. directional, in order to affect only the surface concerned. In other words, the layers on the side surfaces 2b, 2d and the lower surface 2c are not affected by the engraving. The method may include dry engraving.

The third step shown in fig. 2c comprises growing a silicon dioxide layer on all surfaces 2a, 2b, 2c and 2d in order to obtain the desired interference layer thickness and the desired thermal compensation layer thickness. This step may also be performed by thermal oxidation.

Optionally, in a fourth step (fig. 2d), a conductive layer 4 is deposited on the lower surface 2c and on all or part of the side surfaces 2b and 2 d. The deposition may be performed by various known methods, such as PVD, ion implantation, or electrolytic deposition.

Finally, the helical spring therefore has a continuous SiO on all surfaces of the core 2₂A layer having a layer adjusted for thermal compensation on the side surfaces 2b, 2c and 2d and a layer adjusted to obtain a desired color on the upper surface 2a, the thickness of the layer capable of thermal compensation being greater than the thickness of the colored layer.

Of course, this method is not limited to the thermally compensated coil spring and may be applied to a gear, an anchor, or any other component made of silicon.