Manufacturing method of jewel jet material

Abstract

To mold a jet which is small and which cannot be used as it is, into a large mass exhibiting property original to a jet, as possible.SOLUTION: There is provided a production method of a jet material for producing a jet material formed of a molded article 1 molded into a required shape from a raw material S of the jet, comprising: a pulverizing step for pulverizing the raw material S of the jet for forming granules F; a step for sifting the granules F acquired in the pulverizing step into plus mesh and minus mesh by a sifter having 300 μm or smaller apertures; an in-mold adjustment step for putting the granules F of the jet sifted in the sifting step into a molding tool and adjusting the granules until reaching prescribed temperature; a molding step for warming and compressing the granules in the molding tool, for molding the granules into a required shape; and a slow cooling step for, after the molding step, performing slow cooling of the granules in the molding tool.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This invention relates to black gemstones, and in particular, to gemstones made from carbon-based jet (English name: "Jet"; Japanese name: "Kurotama"). Manufacturing method for jewellery jet materials Regarding. [Background technology]

[0002] Jet (English name: "Jet", Japanese name: "Kurotama") is a natural charcoaled fossil wood with a jet black, dry black color that is related to lignite, which is fossilized wood. It is composed of organic carbon containing impurities, and is amorphous, with a Mohs hardness of 2.5 to 4.0 and a specific gravity of 1.30 to 1.35. Jet is treated as a gemstone and is used in various jewelry and ornaments, including necklaces and other personal ornaments.

[0003] In the process of jetting, small jets that are not used for processing, or cutting chips generated during processing or small pieces separated from the product, cannot be used for manufacturing as they are. Therefore, it is considered to mold these into large chunks and use them as jet material, but since the main component is carbon, the technology for this has not yet been established.

[0004] For example, there is a technology for using black silica (graphite silica) as a black gemstone, which is published in JP-A-2007-196019, although its composition and hardness are completely different. This technology processes black silica into powder with a particle size of 5 μm, mixes this with a thermosetting resin such as polyurethane resin, softens the mixture, pours it into a mold, and sinters it at an appropriate temperature. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-196019 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology for utilizing this black silica involves pouring black silica, which has different components and hardness from jet, into a mold together with resin and sintering it. Therefore, simply applying this technology to jet, which is primarily composed of carbon, will result in a product that is significantly different in properties from the original jet, and in particular, it will be unable to express the texture and color unique to carbon-based jet.

[0007] The present invention has been made in view of the above points, and aims to form a jet that is too small to be used as it is into a large lump that retains the original properties of the jet as much as possible. How to manufacture jet materials for jewelry The purpose is to provide. [Means for solving the problem]

[0008] To achieve this object, the present invention Jewelry Jet Materials The manufacturing method of the present invention is a molding method in which a jet raw material is molded into a desired shape. Jewelry Jet Materials Manufacture Jewelry Jet Materials The manufacturing method includes a crushing step in which the raw material for the jet is crushed into powder and a molding step in which the powder obtained in the crushing step is placed in a molding die, and heated and pressurized to mold the jet into a molded body of a desired shape.

[0009] This means: Jewelry Jet Materials When manufacturing, the raw material for the jet is pulverized into powder in the crushing process. Here, it is pulverized in a crusher. The raw material for the jet used in the present invention is small jet that is not used for processing, or cutting chips generated during processing or small pieces separated from the product. Then, in the molding process, the powder of the jet obtained in the crushing process is placed in a mold and heated and pressurized to form a molded product of the required shape. In this case, it is preferable not to add a binder in terms of product value. It is presumed that some impurities contained in the powder act as a binder, and the powder is firmly bonded. This allows Jewelry Jet MaterialsThe texture, color, and other properties expressed in the jet are close to those of the raw stone, and jet that is too small to be used as is can be molded into large chunks that are faithful to the raw material, making it possible to use the jet effectively without waste. still, Jewelry Jet Materials If the properties expressed in the resulting product are close to those of the raw stone, or if it is necessary to change the physical properties to desired values, a small amount of additives may be added.

[0010] If necessary, a sieving step is provided in which the powder obtained in the pulverizing step is separated into oversized and undersized powder using a sieve with an opening of 300 μm or less, and the powder that falls under the sieve is used in the molding step. A sieve with an opening of 200 μm or less is preferable, a sieve with an opening of 150 μm or less is more preferable, a sieve with an opening of 100 μm or less is even more preferable, and a sieve with an opening of 80 μm or less is even more preferable. The sieves may be used in stages. The finer the sieve, the higher the strength and the more preferable it is. This ensures that the powder can be firmly bound. The method may further include, before the molding step, an in-mold conditioning step of placing the under-sieved jet powder particles sieved in the sieving step into a molding die and heating the resulting mixture to the molding temperature.

[0011] In addition, the molding temperature T in the molding step is set to 220°C≦T≦400°C as required. Preferably, it is 250°C≦T≦400°C, and more preferably, it is 300°C≦T≦350°C. If the temperature is less than 220°C, the particles are not bonded sufficiently. If the temperature exceeds 400°C, the components are likely to deteriorate, which is not preferable. This allows the powder particles to be bonded more reliably and firmly.

[0012] Furthermore, as necessary, the molding pressure P in the above molding step is set to 120 MPa ≦ P. Preferably, it is 150 MPa ≦ P, and more preferably, it is 300 MPa ≦ P. If it is below 120 MPa, the particles are not bonded well and a dense structure is not formed. This allows the powder particles to be bonded more reliably and firmly.

[0013] The pressure holding time t in the above molding process is 2 min ≦ t <10min Preferably, the time is 3 min ≦ t <10min , more preferably, 6 min ≦ t <10min If the time is less than 2 minutes, the particle bonds will be weak. This allows the powder particles to be bonded more firmly and reliably.

[0014] It is also effective to provide a slow cooling step of slowly cooling the molded body in the mold after the molding step, thereby making it possible to shorten the molding cycle time. If necessary, additives may be added to the powder or granules used in the molding process, such as various binders and dyes.

[0015] Furthermore, if necessary, the molded body has an upper surface, a side surface continuous with the upper surface, and a lower surface continuous with the side surface, and has an upper chamfered surface at the corner portion between the upper surface and the side surface, and a lower chamfered surface at the corner portion between the lower surface and the side surface, and in the molding process, pressure is applied from the upper surface to the lower surface of the molded body by the mold to mold the molded body. As a result, a molded body having upper and lower chamfered surfaces is formed during molding using the mold. In this case, when the molded body is removed from the mold, the corners between the upper and side surfaces and the corners between the lower and side surfaces, which are formed by pressure, are particularly susceptible to small chipping, but since the upper and lower chamfered surfaces are formed at these corners, chipping is less likely to occur, and therefore damage caused by chipping can be prevented. Jewelry Jet Materials The quality of the product can be improved.

[0016] In this case, it is effective to make the upper and lower chamfered surfaces of the molded body into cut surfaces with a cut dimension C of 0.1 mm≦C≦1 mm, or into curved surfaces with a radius R of 0.1 mm≦R≦1 mm. Preferably, it is 0.2 mm≦R. By chamfering with a small dimension, the overall shape can be maintained and damage to the corners can be prevented. In this configuration, specifically, jet produced in Kuji, Iwate Prefecture is used as the raw material for the jet, In the sieving step, the powder obtained in the pulverizing step is separated into oversize and undersize using a sieve having an opening of 100 μm or less, The molding temperature T in the above molding process is set to 300°C ≦ T ≦ 350°C, The molding pressure P in the above molding process is set to 300 MPa or less. The pressure holding time t in the above molding process is set to 6 min ≦ t.

[0017] Furthermore, if necessary, the side surface of the molded body has three or more successive planes, and the molded body is shaped to have a side chamfered surface at the corner between adjacent planes of the side surface, and the molded body is molded by the mold in the molding process. As a result, when molding is performed using a molding die, a molded body having a side chamfer is formed. Since a side chamfer is formed at the corner between adjacent flat surfaces on the side as well, chipping is less likely to occur, and therefore damage caused by chipping can be prevented. Jewelry Jet Materials The quality of the product can be improved.

[0018] In this case, it is effective to make the side chamfered surface of the molded body a cut surface with a cut dimension C of 0.1 mm≦C≦1 mm, or a curved surface with a radius R of 0.1 mm≦R. Preferably, it is 0.2 mm≦R. By chamfering with a small dimension, the overall shape can be maintained and damage to the corners can be prevented.

[0019] Also, Jewelry jet material according to the present invention is made of a molded body formed into a required shape by heating and pressurizing the powdery raw material of the jet, and has a hardness H (Rockwell Superficial HR15Y) of 60(HR15Y)≦H. Preferably, it is 70(HR15Y)≦H. More preferably, it is 75(HR15Y)≦H.

[0020] In this case, the particle size of the powder is preferably 300 μm or less. More specifically, the powder having a particle size of 100 μm or less, which is the raw material for jet produced in Kuji, Iwate Prefecture, is used, and the powder is heated and pressurized in a molding die to form a molded product into a required shape. It may also contain additives.

[0021] Furthermore, if necessary, the molded body has an upper surface, a side surface continuous with the upper surface, and a lower surface continuous with the side surface, and is configured to have an upper chamfered surface at the corner portion between the upper surface and the side surface, and a lower chamfered surface at the corner portion between the lower surface and the side surface. This results in a molded body having an upper chamfered surface and a lower chamfered surface. In this case, small chips are particularly likely to occur at the corners between the upper surface and the side surface and the corners between the lower surface and the side surface, but since the upper chamfered surface and the lower chamfered surface are formed at these corners, chips are less likely to occur, and therefore damage caused by chips can be prevented. Jewelry Jet Materials The quality of the product can be improved.

[0022] In this case, it is effective to make the upper and lower chamfered surfaces of the molded body into cut surfaces with a cut dimension C of 0.1 mm≦C≦1 mm, or into curved surfaces with a radius R of 0.1 mm≦R≦1 mm. Preferably, it is 0.2 mm≦R. By chamfering with a small dimension, the overall shape can be maintained and damage to the corners can be prevented.

[0023] Furthermore, if necessary, the side surface of the molded body has three or more successive flat surfaces, and the molded body is configured to have a side chamfered surface at the corner between adjacent flat surfaces of the side surface. As a result, a side chamfer is formed at the corner between adjacent flat surfaces on the side surface, so chipping is less likely to occur, and therefore damage caused by chipping can be prevented. Jewelry Jet Materials The quality of the product can be improved.

[0024] In this case, it is effective to make the side chamfered surface of the molded body a cut surface with a cut dimension C of 0.1 mm≦C≦1 mm, or a curved surface with a radius R of 0.1 mm≦R. Preferably, it is 0.2 mm≦R. By chamfering with a small dimension, the overall shape can be maintained and damage to the corners can be prevented. Effect of the Invention

[0025] According to the present invention, Jewelry Jet Materials The texture, color, and other properties expressed in the jet are close to those of the raw stone, and jet that is too small to be used as is can be molded into large chunks that are faithful to the raw material, making it possible to use the jet effectively without waste. [Brief description of the drawings]

[0026] [Figure 1] 1 is a diagram showing a method for manufacturing a jewel jet material according to an embodiment of the present invention; FIG. [Diagram 2] 1A and 1B show a jewel jet material according to an embodiment of the present invention, in which (a) is a longitudinal sectional view and (b) is a transverse sectional view. [Diagram 3] 1 is a process diagram showing a method for manufacturing a jewel jet material according to an embodiment of the present invention. [Figure 4] FIG. 2 is a graph showing temperature changes during the in-mold adjustment process, the molding process, and the slow cooling process in the manufacturing method of the jewel jet material according to the embodiment of the present invention. [Diagram 5] 1A and 1B show an example of the configuration of a molding die used in a manufacturing method for a jewel jet material according to an embodiment of the present invention, where (a) is a longitudinal sectional view and (b) is a transverse sectional view. [Figure 6] FIG. 2 is a diagram showing a method for producing a jewel jet material according to Test Example 1 of the present invention. [Figure 7] 1 is a micrograph of powder particles of raw material ("jet from Kuji, Iwate Prefecture") used in a manufacturing method of a jewel jet material according to a test example of the present invention. [Figure 8]FIG. 2 is a graph showing the relationship between molding pressure P (MPa) and the average hardness (HR15Y) at each molding pressure for the jewel jet material of Test Example 1 of the present invention. [Figure 9] FIG. 1 is a graph showing the relationship between molding temperature T (° C.) and the average hardness (HR15Y) at each molding temperature for the jewel jet material of Test Example 1 of the present invention. [Figure 10] FIG. 1 is a graph showing the relationship between the pressure holding time t (min) and the average hardness (HR15Y) at each pressure holding time for the jewel jet material of Test Example 1 of the present invention. [Figure 11] 1A, 1B, and 1C are micrographs showing the surface condition of the jet material for jewels (molded body) of Test Example 1 of the present invention. [Figure 12] FIG. 11 is a table showing the state of chipping on the upper and lower chamfered surfaces of the jewel jet material of Test Example 2 of the present invention. [Figure 13] 1A is a photograph of a molded product with no chips on the upper chamfered surface, and FIG. 1B is a photograph of a molded product with chips on the upper chamfered surface, which is related to the jewel jet material of Test Example 2 of the present invention. [Figure 14] 1A and 1B show another example of a jewel jet material according to an embodiment of the present invention, where (a) is a longitudinal sectional view and (b) is a transverse sectional view. [Figure 15] 1A and 1B show another example of a jewel jet material according to an embodiment of the present invention, where (a) is a longitudinal sectional view and (b) is a transverse sectional view. [Figure 16] FIG. 2 is a vertical cross-sectional view showing yet another example of a jewel jet material according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Manufacturing method of jewel jet material This will be explained in detail. As shown in FIG. 1, the embodiment of the present invention Jewelry Jet Materials The manufacturing method of the present invention comprises forming a molded body 1 into a desired shape from a raw material S of a jet. Jewelry Jet MaterialsThis is a method for producing J. As mentioned above, jet (English name: "Jet", Japanese name: "Kurotama") is generally a jet-black, dry black, natural carbonized fossil wood related to lignite, which is fossilized wood. It is composed of organic carbon containing impurities, is amorphous, and has a Mohs hardness of 2.5 to 4.0 and a specific gravity of 1.30 to 1.35. Jet is treated as a gemstone and is used in various jewelry and ornaments, including necklaces and other personal ornaments.

[0028] According to an embodiment of the present invention Jewelry Jet Materials Manufactured by the manufacturing method of Jewelry Jet Materials As shown in Fig. 1 and Fig. 2, the molded body 1 is a regular square prism-shaped molded body formed from raw material S into a required shape. The molded body 1 has a regular square upper surface 2, a side surface 3 continuous with the upper surface 2, and a regular square lower surface 4 continuous with the side surface 3, and is molded into a shape having an upper chamfered surface 5 at the corner between the upper surface 2 and the side surface 3, and a lower chamfered surface 6 at the corner between the lower surface 4 and the side surface 3. The side surface 3 of the molded body 1 has three or more successive flat surfaces (four rectangular flat surfaces in the embodiment), and the molded body 1 is molded into a shape having a side chamfered surface 7 at the corner between adjacent flat surfaces.

[0029] The molded body 1 is formed, for example, with a maximum width D of 5 mm≦D≦100 mm and a height H of 1 mm≦H≦100 mm. The upper chamfered surface 5 and the lower chamfered surface 6 of the molded body 1 are formed as cut surfaces with a cut dimension C of 0.1 mm≦C≦1 mm, or as curved surfaces with a radius R of 0.1 mm≦R≦1 mm. In the embodiment, they are formed as cut surfaces. The side chamfered surface 7 of the molded body 1 is formed as a cut surface with a cut dimension C of 0.1 mm≦C≦1 mm, or as a curved surface with a radius R of 0.1 mm≦R. In the embodiment, they are formed as curved surfaces.

[0030] And also, Jewelry Jet Materials The molded body 1 constituting J has a hardness H (Rockwell superficial HR15Y) of 60(HR15Y)≦H.

[0031] According to an embodiment of the present invention Jewelry Jet MaterialsAs shown in Figs. 1 and 3, the manufacturing method of the jet is as follows: As the raw material S of the jet, small jets that are not used for jet processing, or cutting chips generated during processing or small pieces separated from the product, etc. are used, and these raw materials S are Jewelry Jet Materials The process for producing J includes (1) a crushing process, (2) a sieving process, (3) an in-mold adjustment process, (4) a molding process, and (5) a slow cooling process. Each process will be described in detail below.

[0032] (1) Crushing process Using a known grinding machine or the like, the raw material S of the jet is ground into powder F. For example, the raw material S is ground so that it contains a large amount of particles with a particle size of 300 μm or less.

[0033] (2) Sieving process The powder F obtained in the pulverization step is separated into oversized and undersized particles using a sieve with an opening of 300 μm or less. A sieve with an opening of 200 μm or less is preferable, a sieve with an opening of 150 μm or less is more preferable, a sieve with an opening of 100 μm or less is even more preferable, and a sieve with an opening of 80 μm or less is even more preferable. The sieves may be used in stages. A finer sieve is more preferable because it has a higher strength. This allows the powder F to be firmly bound. FIG. 7 shows a micrograph of an example of the sieved powder F. If the sieve exceeds 300 μm, problems will occur in the binding of the particles during molding, so a finer sieve is more preferable because it has a higher strength.

[0034] (3) In-mold adjustment process Referring to the graph shown in FIG. 4, the powder F of the jet sieved in the sieving process is placed in a mold K, and the temperature is raised to the temperature of the molding process. As shown in FIG. 5, the mold K is composed of a cylindrical die 20 in which the powder F is placed and which molds the side surface 3 of the compact 1, a piston-shaped upper punch 21 which presses the powder F in the die 20 from above to mold the upper surface 2 of the compact 1, and a piston-shaped lower punch 22 which presses the powder F in the die 20 from below to mold the lower surface 4 of the compact 1. The upper punch 21 is formed with an upper chamfered surface 23 which molds the upper chamfered surface 5 at the corner between the upper surface 2 and the side surface 3 of the compact 1, and the lower punch 22 is formed with a lower chamfered surface 24 which molds the lower chamfered surface 6 at the corner between the lower surface 4 and the side surface 3 of the compact 1. Further, on the inner surface of the die 20, a side chamfering mold surface 25 is formed for forming a side chamfering surface 7 at the corner portion between adjacent flat surfaces of the side surface 3 of the compact 1. Furthermore, although not shown, a heater is provided for heating the mold K to warm the powder F. In this in-mold adjustment step, pressure may or may not be applied by the mold K. Also, the temperature may be raised in advance to the temperature for the molding step, and then the jet of powder F may be placed into the mold K. At this time, in this embodiment, no additives such as binders are added.

[0035] (4) Molding process With reference to the graph shown in Fig. 4, the jet of powder F, which has been heated to a predetermined temperature and placed in a mold K shown in Fig. 5, is heated and pressurized to form a green body 1 of a desired shape. In the embodiment, no binder is added, but it is presumed that some impurities contained in the powder F act as a binder, and the powder F is firmly bound together.

[0036] The molding temperature T in the molding step is set to 220° C.≦T≦400° C., preferably 250° C.≦T≦400° C., and more preferably 300° C.≦T≦350° C. If the temperature is less than 220° C., the particles will not be bonded sufficiently. If the temperature exceeds 400° C., the composition will be easily altered, which is not preferable.

[0037] The molding pressure P in the molding step is set to 120 MPa ≦ P. Preferably, it is 150 MPa ≦ P, and more preferably, it is 300 MPa ≦ P. If it is below 120 MPa, the bonding between the particles becomes weak and a dense structure is not formed.

[0038] Furthermore, the pressure holding time t in the molding process is 2 min ≦ t <10min Preferably, 3 min ≦ t <10min , more preferably, 6 min ≦ t <10min If the time is less than 2 minutes, the bond between the particles will be weak, making it difficult to obtain the appropriate hardness and susceptible to cracking, which is undesirable.

[0039] (5) Slow cooling process 4, after the molding step, the molded body 1 is slowly cooled in the mold K. In this case, pressure may or may not be applied. After the slow cooling, the molded body 1 is taken out of the mold K.

[0040] The molded body 1 produced by such a production method Jewelry Jet Materials J is hardness H (Rockwell Superficial HR15Y) is 60 (HR15Y) ≦ H. Jewelry Jet Materials J does not contain additives such as binders, Jewelry Jet Materials The texture, color, and other properties expressed in J are close to those of the raw stone. In addition, small jet that cannot be used as is can be molded into a large block that is highly faithful to the raw material S, making it possible to use the jet effectively without waste.

[0041] During molding using the mold K, an upper chamfered surface 5 and a lower chamfered surface 6 are formed, and a molded body 1 having a side chamfered surface 7 is molded. In this case, when the molded body 1 is removed from the mold K, the corners between the upper surface 2 and the side surface 3 and the corners between the lower surface 4 and the side surface 3, which are formed by pressure, are particularly susceptible to small chipping, but since the upper chamfered surface 5 and the lower chamfered surface 6 are formed at these corners, chipping is less likely to occur, and therefore damage caused by chipping can be prevented. Jewelry Jet MaterialsIn addition, the side chamfered surface 7 is formed at the corner between adjacent flat surfaces of the side surface 3, so that chipping is less likely to occur, and therefore, damage caused by chipping can be prevented. Jewelry Jet Materials The quality of J can be improved.

[0042] In this case, the upper chamfered surface 5 and the lower chamfered surface 6 of the formed body 1 are cut surfaces with a cut dimension C of 0.1 mm≦C≦1 mm, so that the small chamfering dimension can maintain the overall shape and prevent damage to the corners. Also, the side chamfered surface 7 of the formed body 1 is a curved surface with a radius R of 0.1 mm≦R, so that the small chamfering dimension can also maintain the overall shape and prevent damage to the corners.

[0043] Next, a test example will be described. <Test Example 1> As shown in Fig. 6, in Test Example 1, jet from Kuji, Iwate Prefecture was used, which was first crushed and sieved to produce powder F. Fig. 7 shows a micrograph of this powder F. A sieve with an opening of 90 μm was used. This powder F was then molded under different conditions in the molding process, namely, molding pressure P, molding temperature T, and pressure holding time t, to produce various molded bodies 1 with a diameter of 13 mm and a thickness of 3 mm. Jewelry Jet Materials Created J.

[0044] And each created Jewelry Jet Materials The hardness H (Rockwell Superficial HR15Y) of J was measured. Based on these results, the relationship between the molding pressure P (MPa) and the average hardness (HR15Y) at each molding pressure, the relationship between the molding temperature T (℃) and the average hardness (HR15Y) at each molding temperature, and the relationship between the pressure holding time t (min) and the average hardness (HR15Y) at each pressure holding time were graphed. The results are shown in Figures 8 to 10.

[0045] From these results, it was found that molding was impossible with a molding pressure of 120 MPa or less, and good molding conditions were achieved with a molding pressure of 300 MPa or more, molding was impossible with a molding temperature of 220°C or less, and good molding conditions were achieved with a molding temperature of 300°C or more, and holding times of 2 minutes or less were found to be impossible with a holding time of 6 minutes or more.

[0046] In addition, Figure 11 shows these Jewelry Jet Materials The results show that the surface of the jet is almost identical to that of a natural jet. Jewelry Jet Materials It can be seen that the following can be obtained.

[0047] <Test Example 2> As shown in Fig. 1, in Test Example 2, the same jet from Kuji, Iwate Prefecture as above was used, and first, it was crushed and sieved to prepare powder F (see the micrograph in Fig. 7). As shown in Fig. 12, sieves with openings of 80 μm, 150 μm, and 180 μm were used to prepare three types of powder F with different particle sizes, and each of these powders F with different particle sizes was molded into a regular square prism with one side of 10 mm and a height (thickness) of 5 mm under the conditions of a molding pressure P of 500 MPa, a molding temperature T of 340°C, and a pressure holding time t of t = 6 minutes. In addition, in the molded body 1 related to the powder F having different particle sizes, the R of the side chamfered surface 7 is set to R=0.5 mm, and the cut dimensions C of the upper chamfered surface 5 and the lower chamfered surface 6 are different, C=0 (none), C=0.2 mm, C=0.3 mm, and C=0.4 mm. Jewelry Jet Materials Created J.

[0048] Then, the upper chamfered surface 5 and the lower chamfered surface 6 of each compact 1 were inspected for chipping. The results are shown in Figure 12. In Figure 12, X indicates that there was a chipping, and ◯ indicates that there was no chipping. No chipping occurred on any of the side chamfered surfaces 7. Figure 13(a) shows a photograph of compact 1 molded from powder F with a mesh size of 150 μm or less and with C=0.3 mm, which was free of chipping. Figure 13(b) shows a photograph of compact 1 molded from powder F with a mesh size of 150 μm or less and with C=0.2 mm, which was free of chipping.

[0049] From these results, chipping was observed in both the upper chamfered surface 5 and the lower chamfered surface 6 when C=0 (none). It was found that in the compact 1 made from powder F with an opening size of 80 μm, both the upper chamfered surface 5 and the lower chamfered surface 6 were excellent and free of chipping when C=0.2 mm or more. In any case, it was found that providing the upper chamfered surface 5, the lower chamfered surface 6, and the side chamfered surface 7 is effective.

[0050] In the above embodiment, the molded body 1 is formed in a square prism shape with an upper chamfered surface 5, a lower chamfered surface 6, and a side chamfered surface 7, and in the test example 1, it is formed in a disk shape without the upper chamfered surface 5 and the lower chamfered surface 6, but it is not necessarily limited to this. For example, as shown in Fig. 14, it is formed in a disk shape with an upper chamfered surface 5 and a lower chamfered surface 6, as shown in Fig. 15, it is formed in a triangular prism shape with an upper chamfered surface 5, a lower chamfered surface 6, and a side chamfered surface 7, or as shown in Fig. 16, a hole 8 is formed through the center of the molded body 1 shown in Fig. 14, and a chamfered surface 9 is also provided on the opening edge of this hole 8. The molded body 1 may be formed in any shape. In the above embodiment, the upper chamfered surface 5 and the lower chamfered surface 6 of the molded body 1 are formed as cut surfaces, but it is not necessarily limited to this and may be formed as curved surfaces, and may be appropriately changed. Furthermore, in the above embodiment, the side chamfered surface 7 of the molded body 1 is formed as a curved surface, but this is not necessarily limited to this, and it may be formed as a cut surface, and may be modified as appropriate.

[0051] Furthermore, the molding die K used in the molding process of the above embodiment is configured with a piston-shaped lower punch 22 that applies pressure from below to the powdered granular material F in the die 20 to mold the lower surface of the molded body 1, but this is not necessarily limited to this, and the lower punch 22 may be integrated with the die 20, and the configuration of the molding die K may be modified as appropriate. Also, in the above embodiment, the powdered granular material F of the raw material S is molded without using additives such as a binder, but this is not necessarily limited to this, Jewelry Jet MaterialsIf the properties expressed in J are close to those of the raw stone, a small amount of additives such as binders may be added. However, it is preferable to avoid using additives such as binders whenever possible. The present invention is not limited to the above-described embodiments of the present invention, and those skilled in the art can easily make many modifications to these exemplary embodiments without substantially departing from the novel teachings and effects of the present invention, and many of these modifications are included in the scope of the present invention. [Industrial Applicability]

[0052] Recently, it was discovered that jet is also produced in the Kuji region of Iwate Prefecture. This jet from Kuji is mined from the same stratum as Mesozoic amber, and it is extremely rare worldwide for jet to be mined from the same stratum as amber. Jewelry Jet Materials This technology makes it possible to mold not only raw stones, but also small jets that would otherwise be unusable, into large chunks that are highly faithful to the raw materials, and it is expected that these can be effectively used for various jewelry and decorative items, including necklaces and other personal accessories. [Explanation of symbols]

[0053] J Jewelry Jet Materials S Raw materials F Powder (1) Crushing process (2) Sieving process (3) In-mold adjustment process (4) Molding process (5) Slow cooling process 1 Molded body 2 Top side 3. Aspects 4 Bottom side 5 Upper chamfer 6 Lower chamfer 7 Side chamfer 8 holes 9 Chamfered Surface K mold 20 Die 21 Upper punch 22 Lower Punch 23 Upper chamfered surface 24 Lower chamfered surface 25 Side chamfered surface

Claims

1. A method for producing a jet material for jewels, which is a molding formed into a required shape from a raw material for jet, comprising: A grinding process in which the raw material for the jet is ground into powder; a sieving step of separating the powder obtained in the pulverization step into an oversize portion and an undersize portion using a sieve having an opening of 300 μm or less; a mold adjustment step in which the under-sieved jet powder particles sieved in the sieving step are placed in a molding die and heated to a molding temperature; a molding step of heating and pressurizing the powder particles in the jet in the mold after the in-mold adjustment step to mold the powder particles into a molded body of a desired shape; A cooling step is provided for cooling the molded body in the mold after the molding step, The molding temperature T in the molding step is set to 220° C.≦T≦400° C., The molding pressure P in the molding step is set to 120 MPa or less. The pressure holding time t in the molding step is set to 2 min ≦ t < 10 min, The molded article of the required shape has an upper surface, a side surface continuous with the upper surface, and a lower surface continuous with the side surface, and has an upper chamfered surface at a corner portion between the upper surface and the side surface, and a lower chamfered surface at a corner portion between the lower surface and the side surface, The upper chamfered surface and the lower chamfered surface of the molded body having the required shape are cut surfaces having a cut dimension C of 0.1 mm≦C≦1 mm, or curved surfaces having a radius R of 0.1 mm≦R≦1 mm, A manufacturing method of a jewel jet material, characterized in that in the molding step, pressure is applied from the upper surface of the molded body toward the lower surface thereof by the mold to mold the molded body into the required shape.

2. The raw material for the jet is jet from Kuji, Iwate Prefecture. In the sieving step, the powder obtained in the pulverizing step is separated into oversize and undersize using a sieve having an opening of 100 μm or less, The molding temperature T in the molding step is set to 300° C.≦T≦350° C., The molding pressure P in the molding step is set to 300 MPa or less.

2. The method for manufacturing a jet material for jewels according to claim 1, wherein the pressurized holding time t in said molding step is set to 6 min≦t<10 min.

3. The side surface of the molded body having the required shape has three or more successive flat surfaces, and the molded body having the required shape has a side chamfered surface at a corner between adjacent flat surfaces of the side surface, 3. The method for manufacturing a jewel jet material according to claim 1, wherein in said molding step, said molding die is used to mold said green body having said required shape.

4. The manufacturing method of the jet material for jewels according to claim 3, characterized in that the side chamfered surface of the molded body of the required shape is a cut surface with a cut dimension C of 0.1 mm≦C≦1 mm, or a curved surface with a radius R of 0.1 mm≦R.

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