Method for manufacturing timepiece component, method for manufacturing timepiece component material, timepiece component, and timepiece component material

Abstract

To provide a method for manufacturing a timepiece component, a method for manufacturing a timepiece component material, a timepiece component, and a timepiece component material, which can improve the quality of the mirror finish of the timepiece component.SOLUTION: The method for manufacturing a timepiece component includes: a step of preparing a metal raw material object; a step of performing forging and heat treatment on the metal raw material object to manufacture a timepiece component material having a portion to be processed that is a target of cutting processing; and a step of cutting out the timepiece component by cutting from the portion to be processed of the timepiece component material and polishing the timepiece component; wherein the forging forms the metal raw material object using a die designed such that the magnitude of distortion of the portion to be processed in the timepiece component material is within a predetermined range, and the heat treatment is performed under heat treatment conditions set in accordance with the magnitude of distortion of the portion to be processed in the timepiece component material formed by the forging, thereby making the crystal grain size of the portion to be processed uniform and making the crystal orientation isotropic.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a watch component, a method for manufacturing a material for a watch component, a watch component, and a material for a watch component. [Background technology]

[0002] Patent Document 1 discloses a method for manufacturing watch parts such as watch cases, in which an ingot whose main component is iron is forged into a roughly cylindrical metal composition, which is then solution treated and then machined (roughly processed) by cutting, grinding, polishing, etc. to form a shape corresponding to the watch case, which is then aged, and then buffed, matte-finished, and textured to form a mirror-finished portion, matte-finished portion, and textured portion into a predetermined pattern, thereby manufacturing a watch case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-70331 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional manufacturing methods have had limitations in improving the mirror finish quality of watch components. For example, as in Patent Document 1, when watch components are manufactured by cutting a cylindrical metal composition, the crystal grain shape becomes directional when the ingot is processed into a cylindrical metal composition by rolling, forging, drawing, or other processes, resulting in anisotropy in the crystal orientation. As a result, anisotropy in the crystal orientation also occurs in watch components manufactured by cutting a cylindrical metal composition. Another method involves plastically processing a metal composition into a case shape by forging, but this method results in localized variations in the processing rate, uneven crystal grain size, and anisotropy in the crystal orientation. The polishing process for achieving a mirror finish is affected by the metal structure, so if polishing is performed when the crystal grain size is uneven or when anisotropy occurs in the crystal orientation, the surface of the watch component cannot be polished uniformly, and there are limits to the quality of the mirror finish. For this reason, it has not been possible to further improve the mirror finish quality of watch components and meet the demand for providing watches with a more luxurious feel. [Means for solving the problem]

[0005] The manufacturing method for watch components disclosed herein comprises the steps of preparing a metal raw material, forging and heat treating the metal raw material to manufacture a raw material for watch components having a processing target portion that is to be cut, and cutting the processing target portion of the raw material for watch components to obtain a watch component by cutting and polishing it, wherein the forging is performed by using a mold designed so that the magnitude of distortion in the processing target portion in the raw material for watch components is within a predetermined range, and the heat treatment is performed under heat treatment conditions set in accordance with the magnitude of distortion in the processing target portion in the raw material for watch components formed by the forging, thereby making the crystal grain size of the processing target portion uniform and the crystal orientation isotropic.

[0006] The method for manufacturing a raw material for watch components disclosed herein is a method for manufacturing a raw material for watch components that is an object to be machined to produce watch components, and comprises the steps of preparing a metal raw material, and forging and heat treating the metal raw material to manufacture a raw material for watch components having a processing target portion that is the subject of cutting processing, wherein the forging is performed by shaping the metal raw material using a mold designed so that the magnitude of distortion in the processing target portion in the raw material for watch components is within a predetermined range, and the heat treatment is performed under heat treatment conditions set in accordance with the magnitude of distortion in the processing target portion in the raw material for watch components formed by the forging, thereby making the crystal grain size of the processing target portion uniform and the crystal orientation isotropic.

[0007] The watch parts of the present disclosure are manufactured by forging and heat treating metal raw material to produce a watch part material having a processing target portion that is subject to cutting processing, and then the material is cut out from the processing target portion and polished to produce a watch part, characterized in that the crystal grain size of the watch part is uniform and the crystal orientation is isotropic.

[0008] The material for watch parts disclosed herein is a material for watch parts that is the object to be machined into watch parts, and is manufactured by forging and heat treating a metal raw material, and has a processing target portion that is the object of cutting processing, and is characterized in that the crystal grain size of the processing target portion is uniform and the crystal orientation is isotropic. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a timepiece component according to an embodiment. [Figure 2] 3 is a flowchart showing the manufacturing process of the timepiece component according to the embodiment. [Figure 3] 1A to 1C are schematic diagrams illustrating the manufacturing process of a timepiece component according to an embodiment of the present invention. [Figure 4] 1A to 1C are diagrams illustrating a forging process according to an embodiment. [Figure 5] 10A to 10C are diagrams illustrating a cutting process according to an embodiment. [Figure 6] 10A to 10C are diagrams illustrating a cutting process according to an embodiment. [Figure 7] 10A to 10C are diagrams illustrating a cutting process according to an embodiment. [Figure 8A] 1 is a graph showing the number of crystal grains by size in an example. [Figure 8B] 1 is a graph showing the number of crystal grains by size in a comparative example. [Figure 9A] 1 is a graph showing the relationship between the diffraction angle and the diffracted X-ray intensity in an example. [Figure 9B] 10 is a graph showing the relationship between the diffraction angle and the diffracted X-ray intensity in a comparative example. [Figure 10]FIG. 1 is a diagram showing the evaluation results of examples and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0010] FIG. 1 is a perspective view showing a watch case 10, which is an example of a watch component. The watch case 10 comprises a case 11 and lugs 15. The case 11 is a cylindrical member made of metal, and houses the dial, movement, and other components (not shown) inside. The lugs 15 are the parts to which the band is attached, and are provided at the 6 o'clock and 12 o'clock positions on the case 11. Each lug 15 is provided as a pair, protruding from the side of the case 11.

[0011] [Watch case manufacturing] Fig. 2 is a flowchart showing the manufacturing process for the watch case 10, and Fig. 3 is a diagram showing an outline of the manufacturing process. The manufacturing process for the watch case 10 comprises a step S1 for manufacturing a watch component material 3, a cutting step S2 for cutting and cutting out the watch case 10 from the processing target portion 31 of the manufactured watch component material 3, and a finishing step S3 for performing finishing work including polishing on the cut watch case 10. In addition, the process S1 for manufacturing the raw material 3 for watch components includes a process S11 for preparing a metal raw material 2, a forging process S12 for forging the metal raw material 2, and a heat treatment process S13 for heat treating the formed product formed by forging.

[0012] [Manufacturing materials for watch parts] In step S1 of manufacturing a watch component raw material 3, first, step S11 is carried out to prepare a metal raw material 2 manufactured from a metal raw material such as stainless steel, titanium, platinum alloy, or gold alloy, which will be the raw material for the watch case 10. In this embodiment, as shown in Figure 3, a cylindrical stainless steel material is prepared as the metal raw material 2. Such a metal raw material 2 can be manufactured by subjecting raw materials such as iron, chromium, or nickel to processes such as melting, refining, continuous casting, and various types of rolling, or it can be prepared by purchasing a round bar available on the market and cutting it to a specified length.

[0013] Next, the forging step S12 in which the metal raw material 2 is forged will be described with reference to Fig. 4. In this embodiment, hot forging is used as the forging, but cold forging may also be used. In the forging step S12, in order to perform hot forging, the metal raw material 2 is heated and placed in a mold 20 consisting of an upper mold 21 and a lower mold 22. Next, the upper mold 21 is brought close to the lower mold 22 using a press, and the metal raw material 2 is crushed and formed. After that, the upper mold 21 is separated from the lower mold 22, and the watch component raw material 3 is manufactured by plastic processing through forging. The watch component raw material 3 is a substantially disc-shaped part that includes a processing target portion 31 and a removal portion 32.

[0014] The die 20 used in forging is designed to keep the magnitude of distortion in the processing target portion 31 of the watch component material 3 within a predetermined range. That is, the die 20 is designed to take into account the deformation of the metal raw material 2 during hot forging, so that the magnitude of distortion in the processing target portion 31 of the watch component material 3 is roughly the same, i.e., within a predetermined range. The predetermined range of distortion in the processing target portion 31 of the watch component material 3 may be any range in which distortion is eliminated, the crystal grain size is uniform, and the crystal orientation is isotropic, through the heat treatment step S13 described below. For example, the magnitude of distortion in the processing target portion 31 may be within ±20% of their average value. Therefore, if the average distortion in the processing target portion 31 is 0.03, the distortion in each portion of the processing target portion 31 is set to fall within a range of 0.024 to 0.036. Furthermore, since the removed portion 32 is removed during cutting, which will be described later, there is no need to consider the magnitude or variation of distortion. For this reason, the portion of the die 20 that forms the removed portion 32 is designed to reduce forging resistance and prevent forging defects, so that plastic workability during forging can be improved. Furthermore, the mold 20, which is made up of the upper mold 21 and the lower mold 22, is designed so that excess material comes out laterally from the outer periphery of the processing target portion 31 as burrs 33, and in this respect, it is also designed so that the magnitude of distortion in the processing target portion 31 is approximately the same. For this reason, the mold 20 is a semi-closed mold.

[0015] 3 and 4, the portion to be removed 32 is a disk-shaped portion with a small thickness, and the portion to be processed 31 is an annular portion that follows the outer periphery of the portion to be removed 32. For this reason, the portion to be processed 31 is less deformed and therefore less distorted, while the portion to be removed 32 is more deformed than the portion to be processed 31 and therefore more distorted.

[0016] In the heat treatment process S13, the watch component material 3 formed in the forging process S12 is heat-treated under predetermined heat treatment conditions to remove distortion in the processing target portion 31 and cause recrystallization, thereby achieving uniform crystal grain size and isotropic crystal orientation in the metal structure of the processing target portion 31. "Uniformity of crystal grain size" means that the standard deviation of the crystal grain size is equal to or less than a predetermined value. For example, if most (e.g., 95% or more) of the crystal grain sizes in the metal structure of the processed portion 31 are in the range of 10 to 500 μm, and the standard deviation of the crystal grain size is 50 μm or less, a histogram showing the frequency of each crystal grain size will have a single peak, and the crystal grain size can be said to be uniform. If the standard deviation is 30 μm or less, the crystal grain size can be said to be even more uniform. On the other hand, if the crystal grain sizes are not uniform, being separated into relatively small and large sizes, the histogram showing the frequency of each crystal grain size will have a split peak, with two peaks, and the standard deviation will be greater than 50 μm. Therefore, whether the crystal grain size is uniform or not can be determined by measuring the crystal grain size and calculating its standard deviation. Isotropic crystal orientation means that the crystal orientation is oriented in a way that does not affect the mirror finish that occurs when polished, and that the relative intensity of the diffraction lines measured by X-ray diffraction is within a range of ±30% or less of the theoretical value. Therefore, the heat treatment conditions may be any conditions that can achieve the above-mentioned uniformity of crystal grain size and isotropy of crystal orientation, and specifically, the conditions include the temperature and time of heating during heat treatment, the rate of change conditions, the holding temperature and time, the temperature and time of cooling, the rate of change conditions, and the atmosphere in each process (degree of vacuum, type of gas, pressure, gas flow rate). For this reason, the heat treatment conditions are set depending on the material, etc., of the watch component material 3. For example, if the material of the watch component material 3 is austenitic stainless steel, the heat treatment temperature is set to a range of 1000 to 1300 degrees Celsius, and the heat treatment time is set to a range of 1 to 180 minutes. Other conditions are also set depending on the material, etc., of the watch component material 3. Furthermore, the design of the mold 20 and the heat treatment conditions can be adjusted by first setting them up through simulation or the like, then experimentally processing and molding the watch component material 3 and evaluating the watch component material 3. The raw material 3 for a watch component is manufactured by the process S1, which includes the process S11 for preparing the metal raw material 2, the forging process S12, and the heat treatment process S13.

[0017] Next, as shown in FIG. 2, a cutting step S2 is carried out in which a watch case 10, which is a watch component, is cut out from the processing target portion 31 of the watch component material 3 by cutting. 5 and 6, the processing target area 31 of the watch component material 3 is sized and shaped so that the case 11 and lug 15 of the watch case 10 can be cut out. Therefore, the watch case 10 can be manufactured by the cutting process S2. The processing target area 31 of the watch component material 3 is sized and shaped so that multiple different types of watch cases 10 can be carved out. For this reason, as shown in Figure 7, watch cases 10B having different shapes of cases 11B and lugs 15B can be carved out from a common watch component material 3.

[0018] Next, a finishing step S3 is carried out, such as polishing the surface of the watch case 10 that has been cut out in the cutting step S2. Specifically, a buffing motor, abrasives, etc. are used to give the surface of the watch case 10 a mirror finish. As a result of the above, as shown in Figure 3, a watch component material 3 is manufactured by performing a forging process S12 and a heat treatment process S13 on the metal raw material 2, and a watch case 10 with a mirror finish is manufactured by performing a cutting process S2 and a finishing process S3 on the watch component material 3.

[0019] [Effects of the embodiment] When manufacturing a watch case 10, which is a watch component, the metal raw material 2 prepared in step S11 is formed into a watch component material 3 in a forging step S12, and then heat-treated in a heat treatment step S13, thereby making it possible to provide a processing target portion 31 in which the crystal grain size is uniform and the crystal orientation is isotropic in the watch component material 3. As a result, the watch case 10 machined out of the processing target portion 31 in the cutting step S2 also has uniform crystal grain size and isotropic crystal orientation. This makes it possible to improve the quality when the surface of the watch case 10 is polished to a mirror finish in the finishing step S3. That is, when mirror finishing is performed by polishing, the polishing is affected by the metal structure, and since the polishing conditions cannot be changed for each metal structure in the watch case 10, if the crystal grain size is non-uniform, there are limits to the quality of the mirror finish. Furthermore, since the polishing processability differs for each crystal orientation, there are also limits to the quality of the mirror finish if the crystal orientation is not aligned within a certain range, i.e., if there is anisotropy. In contrast, in this embodiment, in step S1, the crystal grain size of the processing target portion 31 of the watch component material 3 is uniformed and the crystal orientation is isotropic, and the watch case 10 machined from the processing target portion 31 also has uniform crystal grain size and isotropic crystal orientation, so the quality of the mirror finish in the finishing step S3 can be further improved. This allows for a further improvement in the mirror finish quality of the watch case 10, which is a watch component, and provides a watch with a more luxurious feel.

[0020] [Variations] The watch part is not limited to the watch case 10, but may be any part that constitutes a watch, and is preferably a part that allows the watch to be viewed from the outside. For this reason, the watch part may be any of a variety of ring-shaped parts, such as a bezel, dial ring, crystal bezel, or case back of a see-through caseback. Furthermore, the watch part is not limited to ring-shaped parts, but may also be a dial, case back, band, gear train bridge, oscillating weight, etc. Furthermore, the shape of the processing target portion 31 of the watch part material 3, i.e., the shape of the mold 20, may be set to match the watch part to be manufactured.

[0021] The grain size of the processing target portion 31, i.e., the watch component, is not limited to a range in which all grains are 10 μm or more and 500 μm or less in size, but it is sufficient that a certain proportion, for example, 95% or more, are 10 μm or more and 500 μm or less. Smaller grain sizes improve machinability, so it is more desirable that, for example, 95% or more are 10 μm or more and 50 μm or less. The crystal orientation of the processing target area 31, i.e., the watch component, may be any orientation that does not affect the specularity, and the relative intensity of the diffraction lines measured by X-ray diffraction method is not limited to a range of ±30% or less of the theoretical value.

[0022] The metal raw material 2 is not limited to being formed in a cylindrical shape, and may have any shape that matches the shape of the watch component to be manufactured. For example, when manufacturing a square watch case or watch band, a prismatic metal raw material 2 may be used.

[0023] [Example] Next, examples of the present disclosure and comparative examples will be described with reference to FIGS. 8A, 8B, 9A, 9B, and 10. FIG. The example is a watch case manufactured according to the above embodiment, and the comparative example is a metal raw material 2 plastically worked into the shape of a watch case by forging. 8A and 8B are histograms showing the number of grains by crystal grain size obtained by analyzing the metal composition of a watch case. As shown in FIG. 8A, in the example, the crystal grain size was nearly uniform, and the histogram of crystal grain size also had a single peak. On the other hand, in the comparative example, the metal raw material 2 was plastically processed into the shape of the watch case 10 by forging, resulting in variation in crystal grain size and a split peak in the histogram of crystal grain size. In the example of FIG. 8A, the average crystal grain size was 275.3 μm, the median was 273.0 μm, and the standard deviation σ was 16.43 μm. In the comparative example of FIG. 8B, the average crystal grain size was 100.9 μm, the median was 16.5 μm, and the standard deviation σ was 116.29 μm.

[0024] Figures 9A and 9B show the results of X-ray diffraction analysis of the crystal orientation of the metal composition of a watch case. Figures 9A and 9B show the measurement results for an example and a comparative example, with the vertical axis representing relative intensity based on the value of the highest peak of the diffraction line. In each figure, the black circles represent theoretical values. For example, the theoretical value for austenitic stainless steel is that the highest intensity occurs when 2θ = approximately 51 degrees. If this intensity is defined as 999, the intensity is 446 when 2θ = approximately 60 degrees, and 241 when 2θ = approximately 90 degrees. 9A, the intensity was also highest when 2θ = approximately 51 degrees, and if this intensity was also defined as 999, the intensity was 421 when 2θ = approximately 60 degrees, and 182 when 2θ = approximately 90 degrees. Therefore, in the example, the difference between the theoretical values ​​was 421 / 446 = 0.94 when 2θ = approximately 60 degrees, and 182 / 214 = 0.85 when 2θ = approximately 90 degrees, which were within ±30% of the theoretical values. 9B, the intensity was highest when 2θ = approximately 51 degrees, and if this intensity was also defined as 999, the intensity was 160 when 2θ = approximately 60 degrees, and 44 when 2θ = approximately 90 degrees. Therefore, in the example, the difference from the theoretical value was 160 / 446 = 0.36 when 2θ = approximately 60 degrees, and 44 / 214 = 0.21 when 2θ = approximately 90 degrees, which were outside the range of ±30% or less of the theoretical value. When the inventors evaluated the quality of mirror finishes by polishing, they found that crystal orientation does not affect mirror quality if the relative intensity of diffraction lines measured by X-ray diffraction is within a range of ±30% or less of the theoretical value, but that variations in crystal orientation affect mirror quality if the relative intensity is greater than ±30% of the theoretical value. For this reason, in this disclosure, crystal orientation is defined as isotropic when it is within a range that does not affect mirror quality, i.e., when the relative intensity of diffraction lines measured by X-ray diffraction is within a range of ±30% or less of the theoretical value, and as anisotropic when it is outside that range. Therefore, as shown in FIGS. 9A and 9B, the crystal orientation in the example is isotropic, while the crystal orientation in the comparative example is anisotropic.

[0025] Figure 10 shows the evaluation results of mirror surface quality and machinability for stainless steel watch components in examples and comparative examples with different average grain size, standard deviation, and crystal orientation. The mirror surface quality is expressed on a four-point scale: "◎: very good," "○: good," "△: somewhat poor," and "×: poor." The mirror surface quality may be evaluated visually by the evaluator, or may be evaluated based on measurement results that can evaluate mirror surface quality, such as glossiness. The cutting workability is expressed in three levels: "◎: good", "○: average", and "×: poor". The cutting workability may be evaluated based on, for example, the processing time, i.e., the productivity of the watch component. As shown in Examples 1 to 7, when the standard deviation is as small as 50 μm, the histogram showing the number of grains by crystal grain size has a single peak as shown in Fig. 8A, and the crystal orientation is isotropic as shown in Fig. 9A, the mirror surface quality can be improved to "○" or "◎". In particular, when the average crystal grain size is as small as 100 μm or less and the standard deviation is as small as 30 μm or less, the crystal grains become small and uniform, which greatly improves the mirror surface quality and also improves the machinability. On the other hand, in Comparative Examples 1 to 6, the standard deviation of the crystal grain size was greater than 50 μm, and the crystal orientation was anisotropic, so it was found that the mirror finish quality could not be improved and the machinability was reduced. Therefore, as disclosed herein, by forging and heat treating the metal raw material 2, a material 3 for watch components is produced that has a processing target portion 31 with uniform crystal grain size and isotropic crystal orientation, and by performing finishing processes including cutting and polishing on the processing target portion 31 of this material 3 for watch components to produce watch components, it has been confirmed that high mirror finish quality and good cutting workability can be achieved.

[0026] Summary of this disclosure The manufacturing method for watch components disclosed herein comprises the steps of preparing a metal raw material, forging and heat treating the metal raw material to manufacture a raw material for watch components having a processing target portion that is to be cut, and cutting the processing target portion of the raw material for watch components to obtain a watch component by cutting and polishing it, wherein the forging is performed by using a mold designed so that the magnitude of distortion in the processing target portion in the raw material for watch components is within a predetermined range, and the heat treatment is performed under heat treatment conditions set in accordance with the magnitude of distortion in the processing target portion in the raw material for watch components formed by the forging, thereby making the crystal grain size of the processing target portion uniform and the crystal orientation isotropic. According to the present disclosure, a metal raw material is forged and heat-treated to produce a watch component material having a processing target portion, and the forging die is designed so that the magnitude of distortion in the processing target portion of the watch component material is within a predetermined range, thereby enabling the processing target portion to be formed with little deformation and substantially constant distortion within the predetermined range. Therefore, by performing heat treatment under heat treatment conditions set according to the magnitude of distortion in the processing target portion, the crystal grain size of the processing target portion can be made uniform and the crystal orientation can be made isotropic. Therefore, the watch component cut from the processing target portion by cutting also has uniform crystal grain size and can maintain an isotropic crystal orientation. This improves the mirror finish quality when the surface of the watch component is finished by polishing.

[0027] In the manufacturing method of the watch component of the present disclosure, it is preferable that the uniformity of the crystal grain size of the processing target portion by the heat treatment is such that the crystal grain size of the processing target portion is 10 μm or more and 500 μm or less, and the standard deviation of the crystal grain size of the processing target portion is 50 μm or less. According to the present disclosure, the crystal grain size is set to 10 μm or more and 500 μm or less, and the standard deviation of the crystal grain size in the processing target area is set to 50 μm or less, thereby reducing the variation in crystal grain size and improving the mirror surface quality achieved by polishing.

[0028] In the manufacturing method for a watch component of the present disclosure, it is preferable that the isotropy of the crystal orientation of the processing target portion by the heat treatment is such that the relative intensity of the diffraction lines of the processing target portion as determined by X-ray diffraction method is ±30% or less of the theoretical value. According to the present disclosure, the crystal orientation is considered to be isotropic when the relative intensity of the diffraction lines measured by X-ray diffraction is within ±30% of the theoretical value, so that variations in the crystal orientation do not affect the mirror surface quality resulting from polishing, thereby improving the mirror surface quality.

[0029] In the manufacturing method of the timepiece component of the present disclosure, the forging is preferably hot forging. According to the present disclosure, since raw materials for watch components are processed by hot forging, the raw metal material is heated to a high temperature, which makes it easy to process the raw metal material into raw materials for watch components. Furthermore, while hot forging causes variations in precision due to shrinkage during cooling, the watch components are cut out by cutting, so the watch components can be manufactured with high precision.

[0030] In the manufacturing method for watch components disclosed herein, it is preferable that the metal raw material is formed in a cylindrical shape, the watch component material has a disk-shaped central portion and an outer peripheral portion formed in an annular shape along the outer periphery of the central portion and having a thickness dimension greater than that of the central portion, and the processing target portion is composed of the outer peripheral portion. According to the present disclosure, since the metal raw material is formed into a cylindrical shape, commercially available steel rods and the like can be used, reducing costs. In addition, since the processing target portion of the raw material for watch components is formed into an annular shape, ring-shaped watch components such as watch case bodies, bezels, back covers for see-through backs, and dial rings can be easily manufactured by cutting the processing target portion.

[0031] The present disclosure relates to a method for manufacturing a material for a watch component, which is an object to be machined to produce a watch component, comprising the steps of preparing a metal raw material, and forging and heat treating the metal raw material to manufacture a watch component material having a processing target portion that is the subject of cutting, wherein the forging is performed by shaping the metal raw material using a mold designed so that the magnitude of distortion in the processing target portion in the watch component material is within a predetermined range, and the heat treatment is performed under heat treatment conditions set in accordance with the magnitude of distortion in the processing target portion in the watch component material formed by the forging, thereby making the crystal grain size of the processing target portion uniform and the crystal orientation isotropic. According to the present disclosure, a metal raw material is forged and heat-treated to produce a watch component material having a processing target portion, and the forging die is designed so that the magnitude of distortion in the processing target portion of the watch component material is within a predetermined range, thereby enabling the processing target portion to be formed with little deformation and substantially constant distortion within the predetermined range. Therefore, by performing heat treatment under heat treatment conditions set according to the magnitude of distortion in the processing target portion, the crystal grain size of the processing target portion can be made uniform and the crystal orientation can be made isotropic. Therefore, when the surface of the watch component machined from the processing target portion of the watch component material is polished, the mirror finish quality can be improved.

[0032] The watch parts of the present disclosure are manufactured by forging and heat treating metal raw material to produce a watch part material having a processing target portion that is subject to cutting processing, and then the material is cut out from the processing target portion and polished to produce a watch part, characterized in that the crystal grain size of the watch part is uniform and the crystal orientation is isotropic. According to the watch component of the present disclosure, a metal raw material is forged and heat treated to produce a material for the watch component having a processing target portion, and the crystal grain size of the watch component that is cut out from the processing target portion by cutting is made uniform and the crystal orientation is made isotropic, so that when the surface of the watch component is finished by polishing, the mirror finish quality can be improved.

[0033] In the timepiece component of the present disclosure, it is preferable that the crystal grain size of the timepiece component is 10 μm or more and 500 μm or less, and that the standard deviation of the crystal grain size of the timepiece component is 50 μm or less. According to the present disclosure, it is possible to suppress variations in crystal grain size and improve the quality of the mirror surface obtained by polishing.

[0034] In the timepiece component of the present disclosure, it is preferable that the relative intensity of the diffraction lines measured by X-ray diffraction method is within ±30% of the theoretical value. According to the present disclosure, since the crystal orientation is isotropic, variations in the crystal orientation do not affect the mirror surface quality obtained by polishing, and the mirror surface quality can be improved.

[0035] In the timepiece component of the present disclosure, the material of the timepiece component is preferably one of stainless steel, titanium, platinum alloy, and gold alloy. According to the present disclosure, it is possible to manufacture luxury watch components that are particularly suited to a mirror finish.

[0036] In the timepiece parts of the present disclosure, the timepiece parts are preferably any of the case, bezel, and back cover of a timepiece case. According to the present disclosure, timepiece components that are visible as exterior parts of a timepiece can be given a mirror finish, making it possible to provide a timepiece with a luxurious feel.

[0037] The material for watch parts disclosed herein is a material for watch parts that is the object to be machined into watch parts, and is manufactured by forging and heat treating a metal raw material, and has a processing target portion that is the object of cutting processing, and is characterized in that the crystal grain size of the processing target portion is uniform and the crystal orientation is isotropic. According to the material for watch components disclosed herein, the crystal grain size of the processing target portion is made uniform and the crystal orientation is made isotropic, so when the surface of the watch component that has been cut out from the processing target portion of the material for watch components by cutting, is finished by polishing, the mirror finish quality can be improved.

[0038] In the material for watch components disclosed herein, it is preferable that the material comprises a disk-shaped central portion and an outer peripheral portion that is formed in an annular shape along the outer periphery of the central portion and has a thickness dimension greater than that of the central portion, and that the area to be processed is composed of the outer peripheral portion. According to the material for watch parts disclosed herein, the area to be processed is formed in a circular ring shape, and therefore, by cutting the area to be processed, ring-shaped watch parts such as the body of a watch case, the bezel, the back cover of a see-through back, and the dial ring can be easily manufactured. [Explanation of symbols]

[0039] 2...metal raw material, 3...material for watch parts, 10...watch case, 10B...watch case, 11...body, 11B...body, 15...link, 15B...link, 20...mold, 21...upper die, 22...lower die, 31...area to be processed, 32...area to be removed, S1...process, S11...process, S12...forging process, S13...heat treatment process, S2...cutting process, S3...finishing process.

Claims

1. A method for manufacturing a watch component, comprising: providing a metal feedstock; a step of forging and heat treating the metal raw material to manufacture a material for a watch component having a processing target portion that is to be subjected to cutting processing; a step of cutting out a timepiece component from the processing target portion of the timepiece component material by cutting, and polishing the same; The forging is performed by forming the metal raw material using a die designed so that the magnitude of distortion of the processing target portion of the watch component material falls within a predetermined range, The heat treatment is carried out under heat treatment conditions set in accordance with the magnitude of distortion in the processing target portion of the watch component material formed by the forging, thereby making the crystal grain size of the processing target portion uniform and making the crystal orientation isotropic. A method for manufacturing a watch part, comprising:

2. 2. The method for manufacturing a watch component according to claim 1, The uniformity of the crystal grain size of the processing target portion by the heat treatment is The crystal grain size of the processing target portion is set to 10 μm or more and 500 μm or less, The standard deviation of the crystal grain size of the processed portion is set to 50 μm or less. A method for manufacturing a watch part, comprising:

3. 2. The method for manufacturing a watch component according to claim 1, The isotropy of the crystal orientation of the processing target portion by the heat treatment is The relative intensity of the diffraction lines of the processed portion by X-ray diffraction method is set to ±30% or less of the theoretical value. A method for manufacturing a watch part, comprising:

4. 2. The method for manufacturing a watch component according to claim 1, The forging is hot forging. A method for manufacturing a watch part, comprising:

5. 2. The method for manufacturing a watch component according to claim 1, The metal raw material is formed into a cylindrical shape, The material for watch parts is a disk-shaped central portion; and an outer peripheral portion formed in an annular shape along the outer periphery of the central portion and having a thickness greater than that of the central portion; The processing target portion is configured by the outer periphery A method for manufacturing a watch part, comprising:

6. A method for manufacturing a material for a watch component, which is an object to be machined into a watch component, comprising: providing a metal feedstock; and a step of forging and heat treating the metal raw material to manufacture a material for a watch component having a processing target portion that is to be subjected to cutting processing, The forging is performed by forming the metal raw material using a die designed so that the magnitude of distortion of the processing target portion of the watch component material falls within a predetermined range, The heat treatment is carried out under heat treatment conditions set in accordance with the magnitude of distortion in the processing target portion of the watch component material formed by the forging, thereby making the crystal grain size of the processing target portion uniform and making the crystal orientation isotropic. A method for manufacturing a material for watch parts, characterized by:

7. A watch component is manufactured by forging and heat treating a metal raw material to produce a watch component material having a processing target portion that is a target of cutting, and then cutting the processed target portion and polishing the processed part, The crystal grain size of the watch parts is uniform and the crystal orientation is isotropic. A watch component characterized by:

8. The timepiece component according to claim 7, The crystal grain size of the timepiece component is 10 μm or more and 500 μm or less, The standard deviation of the crystal grain size of the watch component is 50 μm or less. A watch component characterized by:

9. The timepiece component according to claim 7, The relative intensity of the diffraction lines of the watch component by X-ray diffraction method is ±30% or less of the theoretical value. A watch component characterized by:

10. The timepiece component according to claim 7, The material of the watch part is one of stainless steel, titanium, platinum alloy, and gold alloy. A watch component characterized by:

11. The timepiece component according to claim 7, The watch part is any one of the case, the bezel, and the back cover of the watch. A watch component characterized by:

12. A material for watch parts that is an object to be cut into watch parts, The metal material is manufactured by forging and heat treating a metal raw material, and has a processing target portion that is a target of cutting processing, The crystal grain size of the processed portion is uniform, and the crystal orientation is isotropic. A material for watch parts characterized by:

13. The material for watch components according to claim 12, a disk-shaped central portion; and an outer peripheral portion formed in an annular shape along the outer periphery of the central portion and having a thickness greater than that of the central portion; The processing target portion is configured by the outer periphery A material for watch parts characterized by:

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