JP2004294204A - Watch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent influence of potential difference corrosion even when using different kinds of metals as components of a watch, and to use for the watch without hindrance, especially a magnesium alloy having many advantages in weight reduction, in a mechanical characteristic or the like. <P>SOLUTION: This watch is characterized by having a DLC layer formed between different kinds of metals, concerning the watch wherein the different kinds of metals are arranged in the mutually contact state or arranged oppositely. A case 101 is constituted of the magnesium alloy, and a back lid 108 and a screw component 109 are constituted of stainless steel. The DLC layers 108d, 109d are formed on the inner surface of the back lid 108 and on the surface of a male screw 109s of the screw component 109. The DLC layers are formed to have the thickness of about 1-3 μm respectively. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４４】
【表２】

【００４５】
【表３】

【図面の簡単な説明】
【図１】本発明の第１実施形態の概略斜視図。
【図２】第１実施形態の概略部分拡大断面図。
【図３】第２実施形態の概略部分拡大断面図。
【図４】第３実施形態の概略部分拡大断面図。
【符号の説明】
１００…時計（腕時計）
１０１…ケース
１０１ｔ…雌ネジ
１０１ｕ…下地処理膜
１０１ｐ…塗装膜
１０８…裏蓋
１０８ｄ…ＤＬＣ層
１０９…ネジ部品
１０９ｓ…雄ネジ
１０９ｄ…ＤＬＣ層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a timepiece, and more particularly to a component structure suitable as a wristwatch having a component part made of a magnesium alloy.
[0002]
[Prior art]
In general, a wristwatch is used by being fitted to an arm, and therefore, components having high corrosion resistance are used to prevent corrosion due to sweat. However, a wristwatch also has a side surface as a jewelry, so that in many cases, a metal material is often used to give a sense of quality. However, there is a known problem that, when different metal materials are brought into contact with each other or placed opposite to each other, potential difference corrosion occurs between dissimilar metals due to contact of an electrolytic solution such as sweat or seawater. Therefore, in the conventional wristwatch, there is a restriction that the metal parts that come into contact with each other must be made of the same material, or made of materials having characteristics that are electrochemically similar to each other. For example, the exterior of a watch typically consists of a watch case, glass rim, back cover, window material, crown, Makin pipe, Makin, screws, etc., which are made of non-metallic materials such as glass or plastic. Except for the above, the same material or the electrochemically similar material is used as described above, or the surface of the component is treated by plating or the like. (For example, see Patent Documents 1 and 2 below)
[0003]
On the other hand, magnesium alloys that are light and excellent in strength have recently been adopted for chassis of OA equipment. However, due to the difficulty in electrochemical properties, it is not used for the exterior of watches that are exposed to harsh environments, does not sweat, and there are only examples of proposals as guide materials with low electrochemical effects. Absent. (For example, see Patent Document 3)
[0004]
[Patent Document 1]
JP-A-11-118950 [Patent Document 2]
JP-A-5-86492 [Patent Document 3]
JP-A-2001-194469 [0005]
[Problems to be solved by the invention]
By the way, the exterior member of a wristwatch is required to be lightweight, compact, tough, impact-resistant, waterproof, workable, low-priced, and the like. In order to meet these demands, it is desirable that each component of the wristwatch be made of a material that suits its own purpose, that is, a different material for each component. Are required to be combined. However, it has been difficult to combine dissimilar metals due to the potential difference corrosion problem.
[0006]
For example, in the case of the following combination, potential difference corrosion occurs.
▲ 1 ▼ Case: stainless steel, glass rim: titanium, back cover: titanium, makishin pipe: titanium ▲ 2 ▼ case: titanium, glass rim: stainless steel, back cover: stainless steel, makishin pipe: stainless steel ▲ 3 ▼ case: magnesium Alloy, glass rim: stainless steel, back lid: stainless steel, makishin pipe: stainless steel ▲ 4 ▼ Case: stainless steel, glass rim: magnesium alloy, back lid: magnesium alloy, makishin pipe: magnesium alloy [0007]
Among the above various metallic materials, magnesium alloy is the most specific metal that can be used as a structural material, such as 1/4 of the specific gravity of iron and stainless steel, 2/3 of the specific gravity of aluminum, and 1/3 of titanium. It is a light metal. The specific strength of magnesium alloy is 1.5 times that of aluminum alloy, 1.9 times that of stainless steel, 1.8 times that of titanium, and it has higher strength per weight and flexural modulus than plastic. If a part that satisfies the same strength is made, it can be made lighter than plastic. In addition, magnesium alloy has many performances required for exterior parts of watches, such as high electromagnetic wave shielding property, good dent resistance, high vibration and shock absorption, small dimensional change, and good cutability. ing.
[0008]
However, magnesium is extremely susceptible to corrosion as a metal and has a very low standard electrode potential. Therefore, if an electrolyte is present between the metal and a metal having a high electrode potential, magnesium will corrode violently. Magnesium alloys are generally subjected to chemical treatments and the like to prevent corrosion, often forming a corrosion-resistant film on the surface.However, even if such a film is formed, human sweat or Since seawater is a strong electrolyte, it cannot prevent potential difference corrosion when it comes into contact with dissimilar metals. For this reason, conventionally, it has been difficult to use a magnesium alloy for an exterior part of a wristwatch. In particular, magnesium alloys are considered to be unsuitable materials for exterior parts because magnesium alloys cause strong potential difference corrosion with stainless steel, which is relatively frequently used as a material for exterior parts of timepieces.
[0009]
As a method for preventing the potential difference corrosion, a method such as plating treatment or IP (ion plating) can be considered, but a porous surface tends to remain, and a sealing treatment is required. Performing the sealing treatment after the surface treatment is complicated and increases the manufacturing cost. In addition, if the sealing treatment is not sufficiently durable and abrasion resistant, the environment is extremely harsh. It cannot be used for watch parts that are exposed to water, and cannot completely prevent potential difference corrosion.
[0010]
The present invention has been made in order to solve the above-mentioned problems, and is intended to prevent the influence of potential difference corrosion even when a dissimilar metal is used as a component of a timepiece, particularly, to reduce the weight and mechanical properties. It is an object of the present invention to make it possible to use a magnesium alloy having many advantages, such as a wristwatch, without any trouble. Another object of the present invention is to provide a technique that can be implemented at low cost without requiring a complicated process in order to prevent the above-mentioned potential difference corrosion.
[0011]
[Means for Solving the Problems]
As a result of various studies to achieve the above object, the inventors have found that the problem of potential difference corrosion can be solved by forming a DLC layer between different kinds of metals in contact with each other. In particular, it has been found that the present invention enables, for the first time, a magnesium alloy having many advantages such as light weight and high strength to be used as a component of a wristwatch, in particular, an exterior component exposed to a severe environment.
[0012]
That is, the first timepiece according to the present invention is characterized in that a DLC layer is formed between the dissimilar metals in a timepiece in which dissimilar metals are arranged in contact with or opposed to each other. Here, the DLC layer is an abbreviation for diamond-like carbon, and is a carbon layer having an amorphous structure such as diamond and graphite that does not have a certain crystal structure. Microscopically, it has an amorphous structure containing both SP ³ bonds present in diamond and SP ² bonds present in graphite. That is, it is considered that a very strong two-dimensional covalent bond and a three-dimensional covalent bond are mixed. This DLC layer is a hard film having excellent abrasion resistance and an extremely low coefficient of abrasion and having excellent tribological properties because it has the highest hardness among various high-quality thin films. It is also an insulator that does not conduct electricity. The DLC layer is a passivation film, and by interposing it between different metals, it is possible to prevent potential difference corrosion between different metals. Generally, a thickness of 1 to 3 μm has sufficient durability, corrosion resistance and abrasion resistance. Therefore, even if the DLC layer is formed between the components, there is an advantage that the components can be easily fastened and fixed, and the confidentiality and waterproofness can be improved because of the extremely smooth surface. Furthermore, resistance to press fitting or screwing (peeling resistance) is high.
[0013]
Examples of the method for forming the DLC layer include an ionization vapor deposition method, a cathodic arc method, a plasma CVD method, and a sputtering method. More specifically, an ion source method using a hydrocarbon such as gaseous benzene (C ₆ H ₆ ), an arc discharge method using a direct carbon source, a plasma chemical vapor deposition method using methane (CH ₄ ) gas, And an unbalanced magnetron sputtering (USB) method for forming a film by sputtering with non-equilibrium magnetism.
[0014]
In particular, the above invention is extremely effective when both kinds of metal are exterior parts. This is because exterior parts are always exposed to the outside world and may have a chance to come into contact with sweat, seawater, and the like, so that extremely high corrosion resistance is required.
[0015]
Next, in a second timepiece according to the present invention, a first component made of a magnesium alloy and a second component made of a metal other than a magnesium alloy are arranged in contact with each other or opposed to each other. In the timepiece, a DLC layer is formed between the first component and the second component.
[0016]
As described above, magnesium alloys are the lightest among practical metals, have excellent specific strength and specific rigidity, have high electromagnetic wave shielding properties, have good cutting properties, have high dent resistance, high vibration and shock absorption, and have dimensional changes. Since it has the advantage of being small, it is an optimal material as a component constituting a watch component, except for its disadvantageous electrochemical properties. According to the present invention, since the DLC layer is formed between different metals, it is possible to prevent the potential difference corrosion caused by the electrochemical property, which is the biggest drawback of the magnesium alloy. It can be used without any trouble as a component constituting the exterior.
[0017]
Further, in the third timepiece according to the present invention, the first component made of a magnesium alloy and the screw component made of a metal other than the magnesium alloy are screwed with each other, and the first component and the A DLC layer is formed on a screwing surface with the screw component.
[0018]
By forming the DLC layer between the first component and the screw component screwed to the first component, potential difference corrosion can be effectively prevented. In particular, the screwing surface between both parts slides with each other at the time of assembling or repairing, so even if a normal coating is formed on this screwing surface, the screwing surface may be damaged or peeled off by sliding. there is a possibility. However, since the DLC layer has high strength, a smooth surface, and low friction, it is hardly damaged even when formed on such a sliding surface, and has high durability. Further, since the sliding resistance at the time of screwing is low, the assembling work and the disassembling work are facilitated, and further, there is an advantage that crushing and abrasion of the screw thread can be prevented.
[0019]
Next, a fourth timepiece according to the present invention comprises a first component made of a magnesium alloy, a second component made of a metal other than the magnesium alloy, and attached to the first component, A screw component that is made of a metal other than an alloy and connects the first component and the second component, and a DLC is provided between the first component, the second component, and the screw component. It is characterized in that a layer is formed.
[0020]
In each of the above inventions, the first component is preferably an exterior component. Watch exterior components are constantly exposed to the outside air and have the opportunity to touch human hands and the like, and therefore require higher corrosion resistance than built-in components. In particular, portable watches such as watches, pocket watches, and wall clocks require extremely high corrosion resistance because they are always in contact with human hands, sweat, etc., or in some cases, may be immersed in seawater. . By applying the present invention, even a material having extremely poor corrosion resistance, such as a magnesium alloy, can be used as an exterior component exposed to an extremely severe environment.
[0021]
Preferably, the DLC layer is applied on a contact surface or a facing surface of the second component with the first component. Since the surface of the first component made of a magnesium alloy is often subjected to the base treatment as described above, the DLC coating is applied to the second component made of a metal other than the magnesium alloy to thereby increase the film thickness. Accuracy, smoothness, etc. can be secured, and assembling accuracy and sealing (waterproofing) can be improved.
[0022]
Further, it is preferable that the DLC layer is applied to a contact surface or an opposite surface of the screw component to the first component. Also in this case, the accuracy of the film thickness, the smoothness, and the like can be ensured in the same manner as described above, and the assembly accuracy and the sealing property (waterproofing property) can be improved. Further, since the threaded part is usually smaller than the component part to be screwed to the threaded part, it is easier to manufacture the threaded part of the threaded part by DLC coating, and the DLC layer can be formed at low cost. There is. In particular, when the screw component is a male screw, the DLC layer may be formed on the outer surface of the threaded portion, so that the manufacture can be made much easier and more reliably than when the DLC layer is formed on the female screw.
[0023]
The DLC layer preferably has a thickness of 1 to 3 μm. When the DLC layer has a thickness of 1 to 3 μm, sufficient corrosion resistance can be obtained, and there is little influence on dimensions of component parts and screw parts, and flatness is easily obtained. (Waterproofness) can be further improved.
[0024]
Further, it is preferable that an oxide film by a base treatment is applied to the surface of the magnesium alloy. According to this, the corrosion resistance itself of the magnesium alloy can be secured to some extent by the presence of the oxide film, so that the performance of the first component as a watch component can be secured, and the potential difference corrosion by the DLC layer can be prevented. The effect can be further enhanced.
[0025]
In particular, the oxide film is preferably an anodic oxide film. Since the anodic oxide film is dense and has high adhesion, it is most suitable as a surface treatment film of a magnesium alloy, and can exhibit high corrosion resistance.
[0026]
In each of the above means, examples of the magnesium alloy include AZ80 and AZ92-T6 (represented by American Society for Testing and Materials (ASTM)). In particular, AZ80 has a low specific gravity and is excellent in strength among magnesium alloys.
[0027]
The present invention is preferably a wristwatch or other portable watch. Since a portable watch is often placed in a harsh environment, it is particularly effective to apply the present invention. The components that make up the watch include exterior parts such as a watch case (body), glass rim, rotating bezel, back cover, window material, crown, etc. Various components such as a contact spring, a screw, a watch band, a spring bar, and a band piece are included.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
[0029]
[First Embodiment]
FIG. 1 is a schematic perspective view showing the appearance of a timepiece 100 according to a first embodiment of the present invention, and FIG. 2 is a schematic partial enlarged sectional view schematically showing a part of the timepiece 100 according to the present embodiment in an enlarged manner. The timepiece 100 is a wristwatch in the illustrated example.
[0030]
As shown in FIG. 1, a cover glass 102 is press-fitted and fixed to the front side of the case 101 from the front via a waterproof packing 102c (see FIG. 2) made of a synthetic resin or the like. A display unit 100A is provided inside the cover glass 102, and hands 103 are arranged on the display unit 100A. An external operation member (crown) 104 is attached to a side portion of the case 101. Bands 120 are connected to both ends of the case 101. The band 120 is a metal band formed by connecting metal pieces 121.
[0031]
As shown in FIG. 2, a screw hole is formed in the bottom of the case 101, and a female screw 101t is provided therein. The screw hole and the female screw 101t are formed at four places evenly around the axis of the case 101. Inside the case 101, a dial 105, a middle frame 106, a movement 107 and the like are arranged. A back cover 108 is attached to the bottom of the case 101 to close the case 101. The back cover 108 is mounted and fixed to the case 101 by screw parts 109. More specifically, the male screw 109s of the screw component 109 is screwed into the female screw 101t of the case 101. An annular packing 101c is arranged between the case 101 and the back cover 108 to ensure sealing (waterproof).
[0032]
The case 101 is made of a magnesium alloy (for example, an alloy called AZ80 in ASTM notation), and a base treatment film 101u is formed on the surface thereof. On the surface of the case 101 that is exposed to the outside, a coating film 101p is further formed on the base treatment film 101u by baking coating or the like. The undercoating film formed on the surface of the magnesium alloy is particularly preferably an oxide film or another insulating film. Among them, the anodic oxide film is particularly desirable for improving the corrosion resistance of the magnesium alloy because it is dense and has high adhesion.
[0033]
On the other hand, back cover 108 is made of stainless steel. A DLC layer 108d is formed on the inner surface of the back cover 108 (the surface that contacts or faces the case 101). The screw part 109 is also made of stainless steel. A DLC layer 109d is formed on the surface of the male screw 109s of the screw component 109.
[0034]
The DLC layers 108d and 109d can be formed by various methods as described above. For example, a film can be formed by decomposing a hydrocarbon gas by arc discharge plasma in a further vacuum and causing ions or excited molecules in the plasma to collide with a product (back lid 108 or screw component 109). The DLC layers 108d and 109d are preferably formed as thin films having a thickness of about 1 to 3 μm.
[0035]
In the present embodiment, the case 101 (magnesium alloy) and the back cover 108 (stainless steel) are dissimilar metals, but since the DLC layer 108d is interposed on the contact surface between the two, the occurrence of potential difference corrosion is prevented. . In particular, even if sweat or seawater permeates between the contact surfaces of the two companies, there is no possibility that potential difference corrosion will occur. Further, since the DLC layer 109d is also interposed between the case 101 (magnesium alloy) 101 and the screw component 109 (stainless steel), the occurrence of potential difference corrosion is prevented. In particular, even if sweat or seawater permeates between the contact surfaces of the two companies, there is no possibility that potential difference corrosion will occur. Also, since the DLC layer 109d is interposed between the screw parts 109t and 109s of the case 101 and the screw part 109, the screw is prevented from being crushed or worn, and the rotational resistance at the time of screwing is reduced. Also, there is an advantage that the disassembly work becomes easy.
[0036]
In general, the DLC layer has high hardness and low friction, has excellent surface smoothness, and has excellent adhesion, so that the DLC layer is not limited to being formed only on a mere contact surface (contact surface), but may be formed on a press-fit portion. There is no problem even if it is used for screwed parts. Further, since the thickness is about 1 to 3 μm and has sufficient corrosion resistance, there is no problem in the sealing performance and the waterproofness without affecting the dimensional accuracy of the components.
[0037]
[Second embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. Here, the same portions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. FIG. 3 is a schematic partial enlarged cross-sectional view schematically showing a part of the embodiment in an enlarged manner. In the second embodiment, the back cover 108 'is also made of a magnesium alloy (AZ80 in ASTM notation). On the surface of the back cover 108 ', an undercoating film 108u' similar to the above is formed, and in a portion exposed to the outside, a coating film 108p 'is formed on the undercoating film 108u'. Since the case 101 and the back cover 108 'are made of the same metal material, no DLC layer is formed between them.
[0038]
The screw part 109 ′ is not only a part of the male screw 109 s but also a part that contacts or faces the back cover 108 ′ (an inner surface part of a hole inserted into the back cover 108 ′ and an outer part that comes into contact with the back cover 108 ′). The DLC layer 109d 'is formed in a wide range. This DLC layer 109d 'prevents potential difference corrosion between the screw component 109' made of stainless steel or the like, the case 101 and the back cover 108 '.
[0039]
[Third embodiment]
FIG. 4 is a schematic partial enlarged sectional view showing a third embodiment according to the present invention. Also in this embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In this embodiment, no screw component is provided, and instead, a back cover 108 "is screwed to the bottom of the case 101". More specifically, a female screw 101t "is formed in the case 101", and a male screw 108s "is formed in the back cover 108". The male screw 108s "and the female screw 101t" are mutually screwed. A DLC layer 108d "is formed on a portion of the surface of the back cover 108" which is in contact with or faces the male screw 108s "screwed into the case 101". Thereby, potential difference corrosion between the case 101 "and the back cover 108" can be prevented.
[0040]
[Example of experiment]
[Corrosion resistance test]
As shown in Table 1, a wristwatch having the structure shown in the first embodiment was configured and tested as follows. That is, the case was processed with a magnesium alloy and subjected to a base treatment described in the “base” column and a coating treatment described in the “finish” column. On the other hand, secondary parts (back cover, screw parts, winding stem pipe) were formed of stainless steel, and were assembled by performing the processing described in the “Processing for Secondary Parts” column in Table 1. Then, the wristwatch was immersed (semi-immersed) in saline and artificial sweat to perform a corrosion resistance test. The results are shown in Tables 2 and 3. The items described in each column of each table indicate the following contents.
[0041]
"Underground" column: Indicates the method of surface treatment of the underlayer of the case.
Thick film anodizing treatment: forming an anodic oxide film of about 15 μm Thin film anodizing treatment: forming an anodic oxide film of about 10 μm Chemical treatment: oxidizing the surface with acid “Finish” column: Surface finishing method of case (painting color) Is shown.
"Process to secondary parts" column:
"CP-4": Application of wax material "DLC": DLC coating "TiN": TiN coating "Brine" column: Observed by immersing in 5% saline.
"Artificial sweat" column: observed by immersion in a mixed solution (artificial sweat) containing urea, sodium sulfide, ammonia, and sucrose in addition to sodium chloride.
[0042]
From these results, in the case of the DLC and TiN coating-free treatment, air bubbles were generated immediately after immersion in both the saline solution and artificial sweat, and erosion due to potential difference corrosion between the case and the secondary part has started. On the other hand, when the surface of the magnesium alloy was subjected to the thick film anodic oxidation treatment and the secondary parts were subjected to the DLC coating, no erosion occurred at all after immersion for 48 hours. On the other hand, when the magnesium alloy is subjected to the thin film anodizing treatment and the secondary parts are subjected to the DLC coating, the corrosion resistance is improved, but slight erosion occurs in 48 hours. Further, it can be seen that when the TiN coating was applied, the corrosion resistance was improved as compared with the case of CP-4, but the corrosion resistance was inferior to that when the DLC coating was applied, and erosion and porosity occurred.
[0043]
[Table 1]

[0044]
[Table 2]

[0045]
[Table 3]

[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a first embodiment of the present invention.
FIG. 2 is a schematic partial enlarged sectional view of the first embodiment.
FIG. 3 is a schematic partial enlarged sectional view of a second embodiment.
FIG. 4 is a schematic partial enlarged sectional view of a third embodiment.
[Explanation of symbols]
100 ... clock (watch)
101: Case 101t: Female screw 101u: Base treatment film 101p: Paint film 108: Back cover 108d: DLC layer 109: Screw component 109s: Male screw 109d: DLC layer

Claims (10)

A timepiece in which dissimilar metals are arranged in contact with each other or opposed to each other, wherein a DLC layer is formed between the dissimilar metals. In a timepiece in which a first component made of a magnesium alloy and a second component made of a metal other than a magnesium alloy are arranged in contact with each other or opposed to each other, the first component and the second configuration A timepiece, wherein a DLC layer is formed between the timepiece and the component. A first component made of a magnesium alloy and a screw component made of a metal other than a magnesium alloy are screwed with each other, and a DLC layer is formed on a screwing surface of the first component and the screw component. A watch characterized by being made. A first component part made of a magnesium alloy, a second component part made of a metal other than the magnesium alloy, mounted on the first component part, and a metal other than the magnesium alloy, the first component part A timepiece comprising: a screw component connecting the first component and the second exterior component; and a DLC layer formed between the first component, the second component, and the screw component. The timepiece according to any one of claims 2 to 4, wherein the first component is an exterior component. 5. The timepiece according to claim 2, wherein the DLC layer is applied on a contact surface or an opposite surface of the second component to the first component. 6. The timepiece according to claim 3, wherein the DLC layer is attached to a contact surface or a facing surface of the screw component with the first component. The timepiece according to claim 1, wherein the DLC layer has a thickness of 1 to 3 μm. The timepiece according to any one of claims 2 to 7, wherein an oxide film by a base treatment is applied to a surface of the magnesium alloy. The timepiece according to claim 9, wherein the oxide film is an anodized film.

Images