JP4618992B2 - Molding method of ceramic powder - Google Patents

Description

  The present invention relates to the manufacture of a ceramic sintered body that requires high dimensional accuracy in units of microns.

  In recent years, ceramic sintered bodies have been used as machine materials, machine tool parts, measuring devices, engines, blowers, etc. using properties such as high strength, wear resistance, high rigidity, low thermal expansion, heat resistance, and high hardness. It has been used for bearings, tools, lubricants, optical communication parts, and the like. In addition, chemical stability has been applied to chemical devices and equipment using heat insulation or heat transfer.

  Among these, ceramic sintered bodies have come to be used as important element parts of precision instruments used in normal temperature environments such as precision machines and precision measuring instruments. In the background, electronic parts typified by semiconductors are rapidly becoming extremely precise and miniaturized, and processing machines and measuring instruments that manufacture them are required to have submicron or lower precision. It is. Conventionally, stainless steel, aluminum-based alloys, rust-proof iron-based materials and stone materials have been used as structural members for these precision instruments.

  However, in the ultra-precision and ultra-fine processing fields that require machining accuracy of μm or less, the required specifications are so strict that deformation due to the weight of the structure and minute deformation due to temperature and humidity changes become problematic, and for efficiency There are also high demands for faster and lighter machines.

  In order to meet such high-performance quality requirements, various problems have been pointed out with conventional materials, and ceramic sintered bodies have begun to be used.

  In recent years, optical communication using an optical fiber is used with an increase in the amount of information in communication. In this optical communication, an optical connector is used to connect optical fibers or connect an optical fiber and various optical elements.

  For example, in the case of a connector for connecting optical fibers, the end of the optical fiber 3 is held in the through hole 1a formed in the ferrule 1 shown in FIGS. 7 and 8, and the pair of ferrules 1 are inserted from both ends of the sleeve 4. Thus, the tip surfaces 1d processed into a convex spherical shape are brought into contact with each other.

  Various materials such as ceramic sintered bodies, metals, plastics, and glasses have been made as materials for the ferrule 1, but most of them are made of ceramics at present. The reason for this is that ceramics can be machined with high machining accuracy, so the tolerance of the inner and outer diameters can be as high as 1 μm or less, and the sintered ceramics have a low coefficient of friction so that optical fibers can be inserted. This is because of its excellent properties, high rigidity, and low thermal expansion coefficient, it is stable against external stress and temperature change, and has excellent corrosion resistance.

  As shown in FIG. 7 as an outline of the dimensional accuracy required as a ferrule product, the cylindricity and roundness of the outer periphery 1c and the roundness and concentricity of the through-hole 1a are the required dimensional tolerances in units of μm. .

  Further, the shape needs to be processed into a cone on the C surface 1b and a PC surface 1d. In the conventional extrusion molding manufacturing method, the raw material is poured into the extrusion mold continuously from the cylindrical shape, but the dimensional accuracy varies due to the adjustment of the surface roughness and flow angle of the mold. In order to modify the shape, it is necessary to perform processing such as finish polishing or grinding by a machine.

  As shown in FIG. 9, the ferrule manufacturing method removes impurities from starting materials, mixes stabilizers and sintering aids, etc., and specifies a raw material before molding with a binder as a ceramic sintered body. Select a molding die based on the average shrinkage so that the part has the desired dimensions, perform extrusion molding, drying and firing, and inspect the necessary parts by performing mechanical finishing such as grinding and polishing. It was commercialized.

Furthermore, as shown in FIG. 10, the ceramic powder is molded into a predetermined shape by mixing a binder resin with a starting material to form a pre-molding raw material, and extruding the mixture to form a cylindrical molded body. There is a ceramic forming method comprising a step of performing, a step of supplying the formed body to a mold, and a step of heating the mold and subjecting the formed body to second press forming (see Patent Document 1).
JP 2001-145909 A

  In the above-mentioned conventional manufacturing method, extrusion molding has the disadvantage that it can reduce the product cost by being able to perform continuous molding with high accuracy, but it cannot form a special shape, and has an irregular shape by finishing machining such as grinding and polishing. It was indispensable to make.

  In addition, for parts that require a dimensional tolerance of μm or less, which can be said to be ultra-high accuracy, machining such as finish polishing is indispensable due to variations during continuous extrusion molding.

  Since the ceramic sintered body can not be used if there is no cutting allowance for the desired size, it must be disposed of, and since it does not want to be disposed of, the cutting allowance remains in most production lots. The shrinkage rate was shifted to the side with a lot of cutting allowance.

  For this reason, the machining allowance is increased, and it has to be finished to a desired dimension by grinding or polishing, which requires a lot of work time, which increases the manufacturing cost.

  Further, according to Patent Document 1, the mold is taken out from the cooled mold after the mold is heated to a high temperature at which the mold can be molded and press-molded. Since the mold and the molded body shrink at the same time, there is a problem that transferability from the mold is poor and it is difficult to keep the dimensional accuracy of the outer diameter and inner diameter in μm units.

In view of the above problems, the present invention provides a primary molding step of producing a first ceramic cylindrical molded body by extruding a raw material before molding obtained by adding a sintering aid and a resin binder to ceramic powder, and the first ceramics. A secondary molding step of charging the cylindrical molded body into a mold and gradually cooling it while compressing to produce a second ceramic cylindrical molded body, wherein the mold in the secondary molding step is the cylindrical molded body A cylindrical upper mold having a through-hole into which is inserted, a pin having a convex lower surface and a pin inserted into the through-hole, and a concave upper surface, the upper surface being the through-direction of the through-hole The lower mold has a structure composed of three members such that the lower mold is in contact with the lower end surface of the upper mold, and the surface temperature of the lower mold is that of the upper mold. the surface temperature and the same temperature, or the surface of the upper mold A higher temperature than degrees, and is characterized in that it is maintained at a temperature at which the temperature difference is 30 ° C. or less.

  Further, the temperature of the cylindrical molded body is 30 ° C. to 150 ° C., a pin is press-fitted into the inner peripheral portion, and secondary molding is performed while the cylindrical body temperature is gradually cooled to less than 30 ° C.

  Further, the pin has a cylindrical cross section, and the cylindricity and roundness in all the longitudinal directions thereof are 3 μm or less.

  Further, the mold in the secondary molding has a two-stage structure of an upper mold and a lower mold, and the surface temperature of the lower mold is maintained higher by 0 ° C. to 30 ° C. than the upper mold. It is characterized by that.

  According to the present invention, the transferability from the mold is achieved by compression molding, and the dimensional accuracy of the inner diameter and the outer diameter can be kept in units of μm in the secondary molded body.

In addition, no matter how much accuracy the molded body improves, the possibility that accuracy will decrease when fired is 3 μm or less. Since the molded body is placed horizontally by processing into a V-groove type, firing according to the setter Therefore, there is no warping or deformation in the sintered body, and there is no need for processing such as grinding or polishing to increase dimensional accuracy, and a highly reliable product can be provided with minimal processing. it can.

  That is, the present invention can improve the dimensional accuracy of the inner and outer diameters without any additional processing after firing, so that a significant processing time can be reduced.

According to the present invention, primary molding in which a raw material before molding obtained by adding a sintering aid and a resin binder to ceramic powder is formed into a cylindrical molded body by extrusion molding, and the cylindrical molded body is loaded into a heated mold, By using a ceramic powder molding method characterized by performing secondary molding after slow cooling while compressing, it is possible to achieve accuracy without processing the product, and to perform machine finishing. By eliminating it, the production time of the product was greatly reduced and the cost could be reduced.

  FIG. 1 is a manufacturing method showing a method for forming ceramic powder according to the present invention.

  First, a ceramic cylindrical molded body is manufactured by extruding a raw material before molding obtained by adding a resin binder to a starting material. At this time, the dimensions of the inner and outer diameters of the ceramic cylindrical molded body are determined by the dimensions of the mold, but the dimensions of the ceramic cylindrical molded body are determined in advance by taking into account the shrinkage and firing shrinkage during secondary molding.

  In addition, the present invention is a system in which the temperature is softened and cooled while being held in a certain shape, but since the resin is used for the binder, the softening temperature range is wide and the shape can be freely changed. If the temperature is within the softening temperature range, the shape can be kept as it is.

  The binder is not particularly limited as long as it has an action of melting and flowing the ceramic powder by being heated, but there is a problem even if one or more of various binders such as various polymer resins, various surfactants, and paraffin are mixed. There is no.

Furthermore, although the present invention uses a resin system for the binder, the same effect as the present invention can be obtained even if an aqueous system is used, although the softening temperature range is different.

  In the present invention, since the extrusion molding machine used for the primary molding is a two-stage type and a soaking system, the molded body has a uniform density.

  Next, after cutting to a predetermined dimension, the mold is heated to perform compression molding. At this time, the temperature of the ceramic cylindrical molded body is in the temperature range of 30 ° C. to 150 ° C., and while maintaining the temperature of the ceramic cylindrical molded body, a pin is pressure inserted into the inner peripheral portion, and the molded body temperature is set to 30 ° C. A ceramic secondary compact is produced by applying pressure while gradually cooling to below ℃.

  In addition, although the dimensional accuracy of the inner and outer diameters of the ceramic secondary molded body is determined by the accuracy of the pin and the mold, the accuracy of the pin and the mold is cylindricity, roundness, concentricity in all longitudinal directions. The degree is 3 μm or less, and the transferability is achieved by the above compression molding, so that the dimensional accuracy of the inner and outer diameters of the ceramic secondary molded body can be kept in μm units.

  The ceramic secondary compact is placed on a V-type setter with an eccentricity of 3 μm or less, de-bucked and fired to produce a ceramic sintered body, and burrs are removed by outer peripheral lapping to produce a product.

  2 (a) and 2 (b) illustrate the details of the process from loading the molded body by extrusion molding in the above manufacturing method into a mold and compression molding.

  Fig.2 (a) is a figure which shows the structure of a general extrusion molding machine.

  The raw material 5 before molding formed as described above is kneaded and defoamed from the charging port 6 by the kneading section 7 of the charging press molding machine 30, extruded by the screw 8, and shrinkage at the time of molding by compression molding and ceramic firing. A continuous cylindrical molded body 10 is extruded by a molding die 9a selected based on an average shrinkage rate so that a specific portion of the bonded body has a desired dimension.

  Further, the molding die 9a is preliminarily provided with a core pin 9b, and the molding die 9a and the core pin 9b are shrunk at the time of molding by compression molding and a specific portion of the ceramic sintered body has a desired dimension. The dimensions are determined based on the rate. In addition, in the secondary molding, the outer diameter of the core pin 9b is about three times larger than the desired dimension in order to determine the dimensions by finally determining the firing shrinkage rate.

  Furthermore, in the present invention, since the cylindrical molded body 10 has a uniform density, it has a kneading zone A and a kneading zone B, so that the raw material 5 before molding can be heated uniformly and mixed while evacuating. The cylindrical molded body 10 is produced by smelting. At this time, the length in the longitudinal direction is about 600 mm, but the cylindrical molded body 10 is produced by cutting a fixed size.

  In the present invention, there are two kneading zones, but there is no problem with two or more.

  Furthermore, although the heating temperature area | region of the cylindrical molded object 10 shall be 30 to 150 degreeC, in this invention, about 100 degreeC is preferable for temperature. This is because the temperature is determined by the type or ratio of the binder, but if it is 30 ° C. or less, the pre-molding raw material 5 does not flow because it is below the softening temperature, and cannot be supplied to the mold 9a. This is because the mold 9a can be supplied but is too soft to learn from the shapes of the mold 9a and the core pin 9b.

  FIG. 2B illustrates ceramic secondary forming.

  The cylindrical molded body 10 obtained as described above is loaded into a compression molding die 50 which is a secondary molding, and this die 50 has a special shape and a dimensional accuracy suitable for the shrinkage rate, and a lower die 13 and an upper die 12. Since the pin 15 is designed, the cylindrical molded body 10 can be manufactured with a dimensional accuracy and shape commensurate with the shrinkage rate of the final finished product.

  Further, the lower die 13, the upper die 12, and the pin 15 are heated to a temperature region where the cylindrical molded body 10 is softened, and the C surface 15 a provided in the core pin 15 and the PC surface provided in the lower die 13. Apply pressure to follow 13a. Further, the outer diameter of the cylindrical molded body 10 is similarly formed in accordance with the inner diameter of the upper mold 12. At this time, in order to prevent air accumulation from occurring in the inner peripheral portion of the cylindrical molded body 10, air is released by the vacuuming 16.

  At the same time as the pressure is applied, heating to the lower mold 13, the upper mold 12, and the pin 15 is stopped, and gradual cooling with natural heat dissipation is started.

  Here, when it is necessary to further improve the molding accuracy, the heating temperature may be gradually decreased, or when there is a need for tact improvement or the like, air cooling or water cooling may be performed within a range not impairing the effects of the present invention. Control by forced cooling such as may be performed.

  At this time, pressure is applied while being gradually cooled, and the cylindrical molded body 10 is formed in the shape of the lower mold 13, the upper mold 12, and the pins 15 while being compressed.

  Thereafter, drying and firing are performed to complete the ceramic sintered body.

  At this stage, it already has the shape and dimensional accuracy of the finished product. Conventionally, it has been commercialized by inspecting the necessary shape and dimensional correction by performing mechanical finishing such as grinding and polishing. Most of the finishing process is unnecessary, and it is possible to complete the product by simple processing such as removal of fine burrs at the time of compression molding by general peripheral lapping, etc. It can be manufactured at low cost.

  Here, the compression molding of this invention is demonstrated using Fig.3 (a) (b) (c).

  In FIG. 3A, the cylindrical molded body 10 that has been cut to a predetermined size is inserted into an upper mold 12 that has been heated to 30 ° C. to 150 ° C. in advance. At this time, the temperature of the cylindrical molded body 10 is soaked to 30 ° C. to 150 ° C. only by holding for 5 seconds due to the heat conduction of the upper mold 12 and the lower mold 13. The preferable temperature of the cylindrical molded body 10 varies depending on the type or amount of the binder. In the present invention, for example, the upper mold 12 and the lower mold 13 are heated at 120 ° C. for 5 seconds, and the cylindrical molded body 10 is preliminarily formed. Preheated to 100 ° C.

  In the present invention, since the cylindrical molded body 10 is preheated, it can easily reach a soaking state of 100 ° C. in 5 seconds. In addition, the present invention is preheated in advance, but even if it is not preheated, the same effect as the present invention can be obtained only by adjusting the heating temperature and heating time of the upper mold 12 and the lower mold 13. .

  Next, in FIG. 3B, the pin 15 is inserted from the tip portion 15b so as to follow the inner periphery of the upper mold 12, but the inner peripheral portion of the cylindrical molded body 10 is the outer diameter of the tip portion 15b. Because it is larger, it can be inserted easily. This is because the inner diameter is increased three times in advance during the primary molding. Further, the pin 15 has a C surface 15a, and the pin 15 has a high accuracy with concentricity, roundness, and cylindricity of 3 μm or less.

  When the pin 15 is inserted, an air pool is generated in the inner peripheral portion of the cylindrical molded body 10, so that the air pool can be drawn by the vacuuming 16.

  FIG. 3 (c) shows that the cylindrical molded body 10 is soft, so that the pin 15 and the C surface 15a, the lower mold 13a, and the inner periphery of the upper mold 12 can be obtained simply by applying a pressure of 100N to 500N to the pin 15. Can be transferred to the part. However, if the cooling is performed as it is, the cylindrical molded body 10 becomes dense and the shape of the mold 50 is not transferred well. Therefore, although a pressure of 100N to 500N is applied, the pressure used in the present invention can be transferred by applying a method of pressurizing for 5 s at 100 N and then cooling while maintaining the same pressure for 30 s.

  This is because the cylindrical molded body 10 is softened and can be transferred to the mold 50 once by the pressure of the pin 15, but when cooled as it is, the cylindrical molded body 10 itself moves back by a small amount due to thermal expansion and contraction, so the pressure is reduced. If it is cooled while being held, it is prevented from returning to a very small amount, and no shape deformation or deterioration in transferability is observed. That is, by using the softening temperature of the cylindrical molded body 10 itself and cooling it while maintaining the pressure, transferability to the mold 50 is achieved, and furthermore, the mold release from the mold 50 is excellent. When taking out from 50, an excessive load is not applied and the cylindrical molded body 10 itself can be taken out without being scratched, chipped or deformed.

  The range of the pressure varies depending on the kind or amount of the binder, but in the present invention, the pressure is 100N to 500N, and among them, 100N is preferable.

  Thereafter, the lower mold 13 is removed from the upper mold 12, and the cylindrical molded body 10 with excellent dimensional accuracy can be produced.

  The cylindrical molded body 10 has transferability of the lower mold 13, the upper mold 12, and the pin 15 by the above-described method, and can be transferred on all the inner and outer diameters of the cone 15 a, the PC surface 13 a, and the cylindrical molded body 10. .

  FIG. 4 is a cross-sectional view showing the heating method of the mold of the present invention.

A mold 50 for loading the cylindrical molded body 10 of the present invention has a two-stage structure including an upper mold 12 and a lower mold 13. In particular, the lower mold 13 has a PC surface 13a . However, since there is a length in the longitudinal direction from the C surface 15a to the PC surface 13a , the pressure from the pin 15 is not easily transmitted to the lower mold 13.

  Therefore, in the present invention, when the temperature of the lower mold 13 is higher by 0 ° C. to 30 ° C. than the upper mold 12, the pressure transfer is good, and preferably 15 ° C. is increased.

Here, if the temperature difference is less than 0 ° C., the transferability of the PC surface 13a is deteriorated as described above, and the cylindricity of the cylindrical molded body 10 is also deteriorated. When the temperature difference is larger than 30 ° C., the cylindrical molded body 10 is softened and melted from the gap between the vacuum pump 16 of the lower mold 13 and the mold 50 and remains as burrs.

  Further, according to the present invention, as shown in FIG. 5 (a), the inner and outer cylinders of the upper mold 12 have inner and outer cylinders, inner and outer circularities of 3 μm or less, and FIG. The inner die cylindricity and inner circumference roundness of the lower die 13 shown in b) are 3 μm or less, and the cylindricity of the pin 15 and the tip 15b, the pin 15 and the tip as shown in FIG. If the roundness of the portion 15b is 3 μm or less and the concentricity of the pins 15 and 15b is 3 μm or less, if the transfer property is achieved, the cylindricality, roundness, concentricity of the inner and outer diameters of the cylindrical molded body 10 The degree can be 3 μm or less.

  The roundness is a magnitude of deviation from a geometrically correct circle of a circular shape, and the cylindricity means a magnitude of deviation from a geometrically correct straight line of a linear shape. Both are defined in JIS-B0621.

  Thereafter, the molded body 10 obtained by the compression molding by the secondary molding is debindered and subjected to main firing to produce a product.

  At this time, the binder used for the binder removal and the main firing is placed in the V-groove with the molded body 10 sideways as shown in FIG.

  In the case of the V-groove type, since the contact portion of the cylindrical molded body 10 is two tangent lines, the binder is burned and fired only by the radiant heat of the setter 20, so that deformation is small. This is because if the contact portion is large, the heat conduction of the setter 20 is transmitted only on one side, so that a uniform binder cannot be gasified and a sintered body with little deformation cannot be obtained. Therefore, if the V-groove type is used, the contact portion is made smaller, and the binder is removed and fired only by radiant heat, a sintered body with less deformation can be obtained evenly on all the molded bodies 10 instead of only one side. it can.

  In general, in zirconia, the firing peak temperature is 1300 ° C. to 1500 ° C., and alumina is fired at a temperature 100 ° C. higher than that of zirconia, and de-bye varies depending on the type of binder. It is 300 to 500 degreeC.

  Furthermore, since the amount of eccentricity in the longitudinal direction of the V-groove setter 20 is 3 μm or less, it does not occur at all in the warp of the molded body 10.

  Here, the eccentric amount of the setter 20 refers to the longitudinal direction of the setter 20 shown in FIG.

  The setter 20 used in the present invention uses high-purity alumina, and even when it is used repeatedly, the amount of eccentricity remains 3 μm or less. This is because alumina generally starts sintering at 1550 ° C. to complete sintering at 1700 ° C., and therefore does not exhibit flexibility at 1550 ° C. or lower. Therefore, in the cylindrical molded body 10 of the present invention, since complete sintering is 1400 ° C., alumina is not soft and does not deform. However, if there is an impurity, it plays the role of a sintering aid and becomes soft and deforms at a low temperature, but high purity alumina does not deform from the above contents.

  As described above, the present invention uses a temperature characteristic of the cylindrical molded body 10 having a uniform density obtained by extrusion molding, and cuts the size and compresses it into a highly accurate mold. % Transfer makes it possible to finish the cylindrical shape and the roundness of the cylindrical molded body 10 to 3 μm or less. Further, when 100% is not transferred to the high-precision mold 50, the dimensional accuracy of the cylindrical molded body 10 cannot be reduced to the μm unit. Further, also in firing, a sintered ferrule having no deformation or warping due to firing and having a cylindricity, roundness, and eccentricity of 3 μm or less can be obtained by using a high-precision setter 20.

  In the present invention, zirconia is used as a starting material, but the same effect as in the present invention can be obtained even if alumina, metal, or the like is used as a starting material.

  The present invention can be applied to a method for manufacturing a ferrule for an optical connector for connecting optical fibers to each other. The ferrule described above is applied to an optical module that connects an optical element such as a laser diode or a photodiode and an optical fiber. It can also be used.

  Moreover, the ceramic sintered compact in this invention can be applied to the various members used for the connection of optical fibers mentioned above or between an optical fiber and various optical elements, and is not restricted to the ferrule mentioned above. For example, the present invention can be applied to a splicer used for completely connecting optical fibers, a dummy ferrule used for an optical module, and the like.

  In this way, the present invention is a manufacturing method that eliminates the need for this finishing process by increasing the precision of each dimension by compression molding (press molding with a high-precision die) in order to achieve a significant reduction in product cost. It is.

  Examples of the present invention will be described below.

100 of zirconia ferrules having an outer diameter of 2.5 mm, an inner diameter of 1.25 mm, and a length of 10.5 mm were produced from the zirconia raw material by the manufacturing method shown in FIG.

  As for the binder, a resin system was used.

  As shown in FIG. 3, the pressing mold 50 used here uses the upper mold 12 and the lower mold 13 of the precision molding mold 50, and the lower mold 13 includes A pin 15 having a PC surface 13a and having a C surface 15a was inserted into the upper mold 12 from the tip 15b, and compression molded to produce a highly accurate cylindrical molded body 10. At this time, the heating temperature of the upper mold 12 and the lower mold 13 was 100 ° C., and the pin 15 was cooled to 30 ° C. while applying a pressure of 100 N.

  The upper mold 12, the lower mold 13, and the pin 15 are determined by calculating the shrinkage ratio from the mixing ratio of the binder or the like of the raw material before molding in the dimensions of the finished product. In this case, the mold 50 was designed to 75%. Further, the accuracy of the upper mold 12, the lower mold 13, the pin 15, and the tip 15b is as shown in Fig. 5A. 5 and the roundness of the outer circumference is 3 μm or less, and the inner cylinder and the roundness of the inner mold 13 of the lower mold 13 shown in FIG. 5B are 3 μm or less, and FIG. As shown, if the cylindricality of the pin 15 and the tip portion 15b, the roundness of the pin 15 and the tip portion 15b is 3 μm or less, and the concentricity of the pins 15 and 15b is 3 μm or less, transferability can be achieved. The cylindrical molded body 10 having an inner and outer diameter of cylindricity, roundness, and concentricity of 3 μm or less was used.

  At the time of press molding, since it cannot be molded if air remains, it must be removed from the inside of the mold 50, so that the vacuum can be maintained by sucking with a pump 16 from a narrow hole contacting the inner diameter of the mold 50. .

  Further, in the extrusion molding as the primary press, a molded body 11 having a uniform density is produced by two-stage uniform heating by the method shown in FIG. 2A, and the dimension of the molded body 11 is the outer diameter. A product having a diameter of 3.33 mm, an inner diameter of 0.3 mm, and a length of 600 mm was produced and cut to a fixed size.

  In addition, the dimension after the fixed size cut was cut so that the dimension in the longitudinal direction was 14.5 mm, and the weight variation at that time was within 1% in all 100 pieces.

  The setter 20 used for the debuying and firing was performed horizontally by the V-type setter 20 shown in FIG.

  When the ceramic sintered body was observed, some burrs were generated at the joint of the mold 50, but the product could be completed without any problems by removing it by outer peripheral lapping.

以上より、金型５０の加熱温度が３０℃未満だと、温度が低く、金型への転写性が悪いので本願の除冷にはあたらず、筒成形体１０の精度が出ない。 Here, when the mold 50 heating temperature of the present invention is 30 ° C., 70 ° C., 100 ° C., 150 ° C., 170 ° C. and 10 ° C. as Comparative Example 1, the roundness of the outer periphery of the cylindrical molded body 10, cylindricity, The inner roundness and concentricity were measured and it was confirmed which conditions were excellent in dimensional accuracy. At this time, the precision of the upper mold 12, the lower mold 13, the pin 15, and the pin tip 15 b to be used is the same as those shown in FIGS. = 5, and the average value was confirmed.

From the above, if the heating temperature of the mold 50 is less than 30 ° C., the temperature is low and the transferability to the mold is poor, so the cooling of the present application is not performed and the accuracy of the cylindrical molded body 10 is not achieved.

  Next, when the temperature is 150 ° C. or higher, the accuracy is not so good as the outer cylindricality is 2.0 μm, the roundness is 3.0 μm, the inner roundness is 2.0 μm, and the concentricity is 3.0 μm. ˜150 ° C. was found to have excellent roundness, cylindricity, and concentricity of 0.2 μm or less. Among them, the 100 ° C. region is excellent with an outer cylindricality of 0.2 μm, a roundness of 0.1 μm, an inner peripheral roundness of 0.1 μm, and a concentricity of 0.1 μm. The mold 50 was heated at a heating temperature of 100 ° C.

  Further, as Comparative Example 2, the ceramic cylindrical molded body was cooled after the second press molding using a resin binder in the manufacturing method shown in FIG. 10, and was removed and fired to produce a zirconia ferrule.

  The extrusion molding conditions, the extrusion molding method, the second press molding conditions, the precision of the mold 50, and the setter 20 are the same as in the embodiment of the present invention, and only the secondary molding method is different. Further, as in the example of the present invention, the machining was performed by removing the burrs only by the outer peripheral lapping.

  Further, as Comparative Example 3, 100 zirconia ferrules were manufactured by mechanical finishing using an aqueous binder by the conventional manufacturing method shown in FIG.

  At this time, the cylindricity, the roundness, the roundness of the inner circumference, and the concentricity of each sample were measured, and the time until 100 samples were produced was measured. In Example 2 and Comparative Example 2 of the present invention, the accuracy (cylindricity and roundness) of the pin 15 was confirmed by shaking by 2 μm, 3 μm, and 4 μm.

以上より、比較例２では、ピン精度（円筒度、真円度）２μｍは、外周円筒度１．０μｍ、真円度１．１μｍ、内周真円度１．０μｍ、同芯度１．２μｍとなり、ピン精度３μｍでは、外周円筒度１．２μｍ、真円度１．２μｍ、内周真円度１．５μｍ、同芯度１．３μｍとなり、ピン精度４μｍでは、外周円筒度２．０μｍ、真円度２．１μｍ、内周真円度１．９μｍ、同芯度２．２となり、平均作業時間７３ｈとなった。 The cylindricity, concentricity, and roundness are average values of 100 samples, and the working time is average values of Example 2, Comparative Example 2, and Comparative Example 3 of the present invention.

As described above, in Comparative Example 2, the pin accuracy (cylindricity, roundness) of 2 μm is as follows: outer peripheral cylindricity of 1.0 μm, roundness of 1.1 μm, inner peripheral roundness of 1.0 μm, concentricity of 1.2 μm When the pin accuracy is 3 μm, the outer cylinder is 1.2 μm, the roundness is 1.2 μm, the inner circle is 1.5 μm, and the concentricity is 1.3 μm. When the pin accuracy is 4 μm, the outer cylinder is 2.0 μm, The roundness was 2.1 μm, the inner roundness was 1.9 μm, and the concentricity was 2.2, resulting in an average work time of 73 h.

  In Comparative Example 3, the outer peripheral cylindricity was 0.3 μm, the roundness was 0.2 μm, the inner peripheral roundness was 0.2 μm, and the concentricity was 0.3 μm, and the average working time was 120 h.

  In the second embodiment of the present invention, the pin accuracy (cylindricity, roundness) of 2 μm is 0.2 μm for outer cylindricality, 0.2 μm for roundness, 0.2 μm for inner roundness, and 0. When the pin accuracy is 3 μm, the outer cylinder is 0.1 μm, the roundness is 0.2 μm, the inner circle is 0.2 μm, and the concentricity is 0.2 μm. When the pin accuracy is 4 μm, the outer cylinder is 0.4 μm. The roundness was 0.5 μm, the inner circumference roundness was 0.5 μm, and the concentricity was 0.4 μm, resulting in an average working time of 70 h.

  As described above, the processing time of the present invention can be greatly reduced as compared with Comparative Example 3, and the processing time is substantially the same as that of Comparative Example 2, but the accuracy of the product can be greatly improved. Moreover, also in pin precision, if it is 3 micrometers or less, cylindricity, roundness, and concentricity can be improved.

  That is, in Comparative Example 2, the accuracy of the roundness, cylindricity, and concentricity of the inner and outer diameters of the ferrule cannot be improved unless machining is performed as in Comparative Example 3. In the present invention, the pin accuracy is 3 μm or less. By using it, a highly reliable product can be provided only by peripheral lapping that removes burrs.

  Next, the mold 50 in which the cylindrical molded body 10 of Example 2 of the present invention is loaded is a condition that there is no difference in temperature between the upper and lower molds. In Example 3 of the present invention, as shown in FIG. The outer peripheral average cylindricity and the outer diameter roundness of the cylindrical molded body 10 were compared under a condition where the temperature of the mold heating 17 and the lower mold heating 18 was changed intentionally to give a gradient.

以上より、本発明の実施例３において、温度差が０℃、１５℃、３０℃が外周平均円筒度が０．２μｍ以下、外周平均真円度が０．１μｍ以下と良好であり、さらに１５℃が外周平均円筒度０．１μｍ、外周平均真円度０．０８μｍとより良好な結果となった。 The temperature difference between the upper mold 12 and the lower mold 13 was 30 ° C, 15 ° C, 0 ° C, -15 ° C, -30 ° C, and -45 ° C.

As described above, in Example 3 of the present invention, the temperature difference is 0 ° C., 15 ° C., and 30 ° C., the outer peripheral average cylindricity is 0.2 μm or less, and the outer peripheral average roundness is 0.1 μm or less, and 15 The results were more favorable at 0 ° C. with an outer peripheral average cylindricity of 0.1 μm and an outer peripheral average roundness of 0.08 μm.

  Accordingly, in the present invention, a product with higher reliability can be provided by providing a temperature gradient.

It is a flowchart which shows the manufacturing method of the ceramic sintered compact of this invention. (A) which shows the manufacturing method of the ceramic molded body of this invention is a perspective view (b) sectional drawing. (A) (b) (c) is sectional drawing which shows the compression molding of this invention. It is sectional drawing which shows the heating method of this invention. It is a perspective view which shows the precision part of the metal mold | die and pin of this invention. It is a figure which shows the baking method of this invention. It is a fragmentary sectional view which shows the ferrule which is a connector member for optical communications. It is sectional drawing which shows the connector for optical communication using a ferrule. It is a flowchart which shows the manufacturing method water when using the conventional water-system binder. It is a flowchart which shows a manufacturing method when using the conventional resin binder.

Explanation of symbols

1: Ferrule 1a: Through-hole 1b: C surface 1c: Periphery 1d: PC surface 2: Support body 3: Optical fiber 4: Sleeve 5: Raw material 6: Molding port 7: Kneading part 8: Screw part 9a: Molding metal Mold 9b: Core pin 10: Cylindrical molded body 10a: C surface 10b: PC surface 12: Upper mold 13: Lower mold 13a: PC surface 15: Pin 15a: C surface 15b: Tip 16: Vacuum pump 17: Upper metal Mold heating 18: Lower mold heating 20: Setter 30: Extruder 50: Mold

Claims (3)

A primary molding step of producing a first ceramic cylindrical molded body by extruding a raw material before molding obtained by adding a sintering aid and a resin binder to ceramic powder;
A secondary molding step of loading the first ceramic cylindrical molded body into a mold and slowly cooling while compressing to produce a second ceramic cylindrical molded body,
The mold in the secondary molding step includes a cylindrical upper mold having a through hole into which the cylindrical molded body is inserted, a pin having a convex lower surface and inserted into the through hole, and a concave shape. And has a structure composed of three members: a lower mold that comes into contact with the lower end surface of the upper mold so that the upper surface is positioned on an extension line in the penetration direction of the through hole. ,
The surface temperature of the lower mold is the same as the surface temperature of the upper mold or higher than the surface temperature of the upper mold , and the temperature difference is maintained at a temperature of 30 ° C. or less. A method for forming a ceramic powder, comprising:   In the secondary forming step, the temperature of the first ceramic cylindrical molded body is set to 30 ° C. to 150 ° C., a pin is press-fitted into the inner peripheral portion, and the temperature of the first ceramic cylindrical molded body is gradually cooled to less than 30 ° C., The method for forming a ceramic powder according to claim 1.   The method for forming a ceramic powder according to claim 2, wherein the pin has a circular cross section, and the cylindricity and roundness in all of the longitudinal directions thereof are 3 μm or less.

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