Degreasing metal plate setter and material for ceramic balls using the same, and ceramic balls

Abstract

To provide a metal plate setter used in degreasing a material for a ceramic ball, which reduces defective deformation and concave defect formation without concentration of a weight of a molded body to one point when performing degreasing of the material for the ceramic ball, the material for the ceramic ball using the same, and the ceramic ball.SOLUTION: A metal plate setter 6 used in degreasing a material for a ceramic ball is characterized in that a conical recess 7 is formed in the metal plate setter. Also, a hole penetrated through an opposite surface is formed at a tip of the conical recess formed on one face of the metal plate setter. Also, a material of the metal plate setter is iron or an iron-based alloy. Moreover, a tilt angle of the conical recess is 10 degrees or over and 60 degrees or under. Also, a surface of the metal plate setter is coated with ceramic.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The embodiments described below relate to a degreasing metal plate setter, a raw material for ceramic balls using the same, and ceramic balls.

Background Art

[0002] Various ceramic materials have characteristics such as high hardness, insulation, and wear resistance. In particular, fine ceramics with increased purity and uniform particle size exhibit characteristics used in various fields such as capacitors, actuator materials, and refractory materials. Among them, there are ball applications that utilize wear resistance and insulation. Ball applications include bearings, jigs, tools, gauges, solenoid valves, check valves, and various valves. Among these, for bearing applications, materials such as aluminum oxide, silicon nitride, and zirconium oxide are used (Patent Documents 1 to 2). For example, Patent Document 1 discloses a bearing ball using a silicon nitride material, and Patent Document 2 discloses a bearing ball using a zirconium oxide material.

[0003] In the process of manufacturing these bearing ball materials, a method of sintering a formed body is used. Also, the forming method uses press forming with a mold. Press forming is generally a method of inserting powder between an upper punch and a lower punch and applying pressure to obtain a pressed formed body. Since the press formed body is formed by a uniaxial load from above and below, it is performed to obtain a homogeneous formed body by applying pressure from all directions by cold isostatic pressing (CIP) (Patent Document 3). According to Patent Document 3, during press forming, in order to protect the mold, between the tip of the upper punch and the tip of the lower punch ​​​​​​​​​​​​​ A gap must be created during press molding. Therefore, the molded body will have a spherical section and a strip-shaped section. To achieve this, a bearing ball material having a spherical portion and a strip-shaped portion is disclosed.

[0004] Furthermore, a method for forming ceramic ball material by rolling granulation without using a press die is disclosed. This has been done (Patent Document 4). According to Patent Document 4, molding by rolling granulation eliminates the strip-like portion. It can be used to mold materials for ceramic balls.

[0005] Furthermore, these materials for ceramic balls Ceramic parts obtained by sintering This is disclosed (Patent Document 5). 。 [Prior art documents] [Patent Documents]

[0006] Patent document 1: Japanese Patent Application Laid-Open No. 6-48813 Patent document 2: Japanese Patent Application Laid-open No. 18620 / 1983 Patent Document 3: International Publication No. 2023 / 003040 Patent Document 4: Japanese Unexamined Patent Publication No. 2001-146479 Patent Document 5: Japanese Patent Application No. 2023-196866 [Overview of the project] [Problems that the invention aims to solve]

[0007] The expanding market for ceramic bearing balls is leading to their use in larger bearings. Ceramic balls of a specific shape are now being used. The manufacturing process involves first mixing ceramic powder with an organic binder and then performing powder molding. A molded body is obtained by this process. Next, the molded body is degreased and sintered to obtain a sintered body. At this time, the sintered body This is called the material for ceramic balls. Next, the sintered body (the material for ceramic balls) is polished. These are ceramic bearing balls.

[0008] By the way, as the molded body gets larger, deformation and damage can occur during the manufacturing process due to the weight of the molded body. When a molded body is made by press molding as shown in Figure 2, the surface of the molded body is spherical, so in the sintering vessel... The setter will make contact with a flat (planar) plate at a point rather than across a surface. It contains an organic binder. In its shrunk state, the molded body retains its shape, but degreasing removes organic matter, making it brittle. In this condition, deformation and other defects are more likely to occur. For example, the part that comes into contact with the setter becomes flat. This can lead to deformation defects, or the force applied to a single point can cause it to react with the setter and burn out. This can result in indentations. Therefore, in the process from degreasing to the completion of sintering, the molded body It was necessary to increase the contact area with the setter to distribute the weight of the molded body. When ceramic ball material with deformation defects or dent defects is processed into bearing balls... Furthermore, achieving a spherical shape requires a long polishing process. In addition, impurities that cannot be removed during the polishing process remain. If only good bearing balls remained, only unreliable bearing balls were obtained.

[0009] During the degreasing and sintering process, there are flat metal plate shelves in the degreasing furnace for placing the molded body. When many molded bodies are placed on the metal plate shelf, the metal plate seals when the degreasing furnace is inserted and removed. The molded and degreased parts on the turntable may come into contact and be damaged as they move. Ta.

[0010] Even when the molded bodies are placed and arranged in the ceramic setter, the same applies when loading and unloading them from the degreasing furnace. There was a possibility that the ceramic setter could be damaged by moving. Also, Using a ceramic setter in the debinding process also has the problem that a large number of ceramic setters are required. Furthermore, when using a ceramic setter, the amount of heat to be applied increases by the amount of the ceramic setter, resulting in high energy costs. Also, arranging the ceramic setters on a shelf board or the like requires labor. The present invention solves such problems, and provides a metal plate setter capable of reducing the occurrence of deformation defects and dent defects without concentrating the weight of the formed body at a single point when performing the debinding process. In addition, the present invention provides a ceramic ball material with few deformation defects and defects, and a ceramic ball obtained by polishing the ceramic ball material using a metal plate setter.

[0011]

Means for Solving the Problems

[0012]

Brief Description of the Drawings

[0014] The following describes a metal plate setter and a ceramic ball setter using the same, referring to the drawings below. The materials and embodiments of the ceramic balls will be described in detail.

[0015] The metal plate setter used for degreasing the material for ceramic balls according to the embodiment is a metal plate A cone-shaped recess is formed in the setter.

[0016] Figure 1 shows the material for ceramic balls made by press molding. In Figure 1, 1 is the ceramic ball The material for the ball is shown in Figure 2, where 2 is the spherical part and 3 is the strip-shaped part. Also, Figure 2 shows the material for the ceramic ball. This shows the press die used for forming. In Figure 2, 4 is the press die and 5 is the punch section. Figure 3 shows This shows a material for ceramic balls produced by rolling granulation. Figure 3 shows the strip-shaped portion 3 as shown in Figure 1. It lacks other features, and the material for the ceramic ball is only for the spherical part.

[0017] Figure 4 shows an example of a metal plate setter according to an embodiment in which ceramic ball material is set. This is a cross-sectional view. In Figure 4, 1 is the material for the ceramic ball, and 6 is where the cone-shaped recess is formed. A metal plate setter, 7 is a cone-shaped recess formed in the metal setter. Ceramics The ball material 1 may have a strip-like portion as shown in Figure 1, or it may be a spherical shape without a strip-like portion as shown in Figure 3. This is also good. The ceramic ball material 1 consists of a metal plate setter 6 and the slope of a cone-shaped recess 7. Because contact occurs along a circular line, the weight is distributed rather than concentrated at a single point. Also, the direction of force It is also approximately perpendicular to the slope of the conical recess 7. Furthermore, in the following drawings, the conical recess is As explained, the same effect can be obtained even with a spherical concave shape.

[0018] Figure 5 is a perspective view showing the entire metal plate setter 6 of Figure 4. The tar 6 has nine conical recesses 7 arranged in a 3x3 grid (hereinafter referred to as "recesses"). The material 1 for the ceramic ball is placed in this recess 7. In other words, Figure 4 mentioned above is equivalent to Figure 5. This is a diagram showing part B. The number of recesses is not limited to this; it can be many or few. The placement of the recesses may be at any position on the flat plate. Also, the diameter of recess 7 in Figure 5 and The spacing is all the same, but to degrease the materials for ceramic balls of different sizes at the same time. Furthermore, the diameters and spacing can be of different sizes.

[0019] The size (diameter) of the recess 7 depends on the size (diameter) of the ceramic ball to be degreased. If the diameter of the recess 7 is larger than the diameter of the molded body of the ceramic ball material 1, the amount of degreasing will decrease, resulting in poor cost performance. If the spacing between the recesses 7 is too wide, the amount of degreasing will also decrease, resulting in poor cost performance. However, the spacing between the recesses 7 can be larger than the diameter of the molded bodies in order to position the molded bodies so that they do not overlap. In other words, if the diameter L of the ceramic ball base body 1 is the same, the distance P of the recess 7 is greater than the diameter L of the ceramic ball base body (P>L). Note that the spacing between the recesses is, for example, at the apex of the recess. 71 This represents the distance between them.

[0020] Furthermore, the thermal expansion coefficient of the metal plate setter 6 is greater than that of the ceramic molded body. Therefore, if the recess 7 is deep and the inclination angle A is large, a tightening force is applied. Ceramics after degreasing The material used for the ball is brittle because the organic components (binder) have been removed, and the metal plate setter is broken. It can become embedded in the fat, potentially causing damage or peeling when removing the degreased material. Conversely, it can also cause indentations. If the recess is shallow and the inclination angle is small, the molded body and degreased body will come out of the recess when the metal plate setter is moved. This may cause collisions with other molded or degreased materials. For this reason, the depth H of the metal plate setter is The material for ceramic balls is 10-30% of the diameter L (0.1L ≤ H ≤ 0.3L) It is preferable to do so.

[0021] In contrast, Figure 6 shows a comparative example: setting ceramic ball material into a metal plate setter. This is a cross-sectional view of one example. 8 is a flat metal plate setter (hereinafter referred to as "flat metal plate setter") (abbreviated) The ceramic ball material 1 has a flat metal plate setter 8 at one point on the spherical part 2. They are in contact. Therefore, the load on the ceramic ball material 1 is applied to the single point of contact, Furthermore, the direction in which the load is applied is perpendicular to the direction of the flat plate. For this reason, small and light ceramic balls There is no problem with materials intended for general use, but if the material is intended for large, heavy ceramic balls, its own weight will cause problems. The spherical shape may deform. Also, it may react with the flat metal plate setter and partially peel off. This could potentially lead to defects such as those mentioned above.

[0022] Furthermore, the metal plate setter according to this embodiment has a conical recess formed on one side at its tip. It is characterized by having a hole that penetrates through to the opposite side.

[0023] Figure 7 shows an example of a metal plate setter according to the embodiment. Figure 7(a) is a top view, and the top view ( A conical recess 7 is formed from one side. Figure 7(b) shows the X-X' plane of Figure 7(a). This is a cross-sectional view. In Figure 7, the tip of the conical recess 7 formed on one side of the metal plate setter 6. A hole 9 is formed at the end that penetrates to the opposite side. Figure 7(c) shows the ceramic in Figure 7(b). This is a cross-sectional view with the ball material 1 installed.

[0024] The material used for ceramic balls generates gas during degreasing. These gases are contained within the molded product. It is generated by the component that forms the basis of the gas component. The component that forms the basis of the gas component is added during molding. The organic binder, the gas components in the pores present between the granulated powders and particles of the molded body, and furthermore, Various substances, such as moisture from the atmosphere absorbed by the object, can be vaporized by heating. (See Figure 4) As shown above, the ceramic ball material 1 before degreasing is in contact with the metal plate setter 6. When the contact point is lower, there is a space, and the ceramics before degreasing and sintering The gas generated from the ball material 1 is discharged into the space below, and then into the ceramic ball material It is released to the outside through gaps such as the contact point between 1 and the metal plate setter 6. For this reason, a hole 9 is formed. This allows for smoother gas release from the space within the metal plate setter. Cut.

[0025] In the metal plate setter 6 shown in Figure 7, there is a lower limit to the diameter of the ceramic ball material 1 due to the presence of holes 9. That is, if a ceramic ball material 1 with a small diameter is placed in the metal plate setter 6, it will fall without making contact with the inclined surface. Furthermore, when heated to the degreasing temperature, the expansion rate of metal is greater than that of ceramics, so the expansion of the metal must be taken into consideration. hole It is necessary to use the diameter. That is, when the diameter of the hole 7 is Db, when the degreasing temperature is reached, the diameter L is greater than the hole diameter Db (L <Db)。

[0026] Furthermore, in the embodiment, the metal plate setter is made of iron or an iron-based alloy. 。

[0027] The metal sheet setter is used in the degreasing process. The degreasing process breaks down organic components such as binders. This process involves heating to a temperature above a certain level to remove organic components. For example, the degreasing process is performed at 400-700°C. The degreasing process is carried out in air or a non-oxidizing atmosphere within the temperature range. It is preferable that the metal is stable at certain temperatures and atmospheres, and is easy to process and resistant to deformation. The metal materials that satisfy these conditions and are inexpensive are iron and iron-based alloys. Iron-based alloys are These include carbon steel such as rolled steel, chromium steel, and alloy steels such as stainless steel. Of these, stainless steel Resistant steel is preferable because it has high resistance to high-temperature corrosion.

[0028] Furthermore, the metal plate setter according to the embodiment has a conical recess with an inclination angle of 10 degrees or more and 60 degrees or more. It is below.

[0029] As mentioned above, the thermal expansion coefficient of the metal plate setter 6 is greater than that of the ceramic molded body. Therefore, if the recess 7 is deep and the inclination angle A is large, a tightening force will be applied. The material for Lamix Balls (hereinafter abbreviated as "degreased material") has had its organic components (binders) removed. Because it is brittle, the metal plate setter 6 gets stuck in the degreased body, causing scratches and peeling when the degreased body is removed. This may occur. Conversely, if the recess is shallow and the inclination angle A is small, the metal plate setter 6 When moving, there is a possibility that the molded or degreased body may come out of the recess 7 and collide with other molded or degreased bodies. It also has properties. For this reason, the inclination angle of the recess is preferably between 10 degrees and 60 degrees. If angle A is less than 10 degrees, the molded body or degreased body is more likely to come off the recess during movement. If the angle exceeds 60 degrees, the edges of the recess may damage the degreased material due to thermal contraction during cooling. It has this property. For this reason, the inclination angle is preferably between 15 degrees and 50 degrees, and between 20 degrees and 40 degrees. That is even more preferable.

[0030] Furthermore, the surface of the metal plate setter according to the embodiment is coated with a ceramic coating. ru.

[0031] Material 1 for ceramic balls becomes contaminated with metal stains when it rubs against the metal plate setter 6. There is a possibility. When installing or removing material 1 for ceramic balls, and as mentioned above. This is because friction occurs during heating and cooling due to the difference in thermal expansion between ceramics and metal. The dirt may not be removed at the high temperatures during sintering, and may remain on the surface of the material for the ceramic balls. Adhesion is possible. If this metallic contamination cannot be removed during the post-sintering processing, bearing This results in a foreign object defect in the bearing ball. This foreign object defect reduces the performance of the bearing ball. Therefore, the adhesion of metal contaminants can be reduced during the degreasing process. For this reason, the metal setter It is preferable to apply a highly heat-resistant ceramic coating to the surface.

[0032] Ceramic coatings include vapor deposition, thermal spraying, and painting methods, and are used for metal plate sets. This method involves coating the surface of a ceramic material with a thin ceramic film up to several tens of micrometers thick. By coating the metal surface with a mixed film, the adhesion of metal stains is prevented. This is possible. The ceramic coating is made of the same material as the ceramic ball material. It is preferable that they be of the same type, with similar strength and resistance to friction. This is because there is less adhesion of the compound.

[0033] As mentioned above, the metal plate setter 6 is ideal for degreasing the ceramic ball material 1. At that time, the materials for ceramic balls were silicon nitride sintered body, aluminum oxide sintered body, and oxide It is one of the following types of zirconium sintered bodies.

[0034] At this time, the ceramic ball material 1 is silicon nitride, aluminum oxide, zirconium oxide It is preferable that one or more of the following types of nium be the main component (50% by mass or more). Also, nitrogen Contains 85% or more by mass of one or more of the following: silicon dioxide, aluminum oxide, or zirconium oxide. It is more preferable to do so. Ball-shaped ceramic sintered bodies are used as bearing balls. It is included. The ceramic bearing balls use the aforementioned materials. In particular, Silicon nitride sintered bodies have excellent wear resistance and are effective as bearing balls.

[0035] Furthermore, the ceramic ball material 1 is silicon nitride, aluminum oxide, zirconium oxide The fact that it contains 85% or more of one or more of the following main components means that, in addition to these main components, It may contain 15% by mass or less of a sintering aid.

[0036] For example, aluminum oxide sintered bodies or zirconium oxide sintered bodies have a Vickers hardness of approximately 1200 to 1700. On the other hand, their toughness is 3 MPa·m. 1 / 2 More than 6MPa m 1 / 2 The Vickers hardness is low, as shown below. In contrast, silicon nitride sintered bodies have a high Vickers hardness of approximately 1400 to 1800. Furthermore, their toughness is 5 MPa·m. 1 / 2 More than 10MPa m 1 / 2 The toughness is high, as shown below. Silicon nitride sintered bodies achieve both high toughness and Vickers hardness, resulting in excellent wear resistance. This is because silicon nitride sintered bodies have a structure mainly composed of β-type silicon nitride crystal particles. β-type silicon nitride crystal particles have an elongated shape, and the complex intertwining of these elongated crystal particles achieves a high toughness value.

[0037] Furthermore, the outer diameter of the ceramic ball material according to the embodiment is 20 mm or more. As such, the materials for ceramic balls include silicon nitride sintered body, aluminum oxide sintered body, and oxide Being a zirconium sintered body means that the molded body, degreased body, and calcined body have an outer diameter of less than 20 mm. Because the assembled structure is lightweight, it is less likely to deform or otherwise be damaged when placed on a flat plate setter. Therefore, a more preferable outer diameter for ceramic ball material 1 is 25 mm or more, and further The preferred outer diameter is 30 mm or more.

[0038] The ceramic ball material obtained as described above can be obtained by polishing. It is suitable as a ceramic ball. That is, a ceramic sintered body as a bearing ball Polishing is necessary to achieve this. Also, the material for ceramic balls is polished to make it spherical. These are called bearing balls.

[0039] Furthermore, the arithmetic surface roughness Ra of the ceramic ball according to the embodiment is 0.01 μm or less. be.

[0040] Manufacturing ceramic balls by polishing the material used for ceramic balls. This can be done. A typical example of sphere polishing is surface plate polishing. For example, ceramic The material for the abrasive ball is inserted between two parallel grinding plates. Due to the movement of the grinding plates, One example is processing the material for the Lamix ball into a perfect sphere. The surface of the bearing ball. The roughness is specified in ASFM F2094. The bearing balls are AS depending on the application. Grades conforming to TMF2094, ISO26602, or JISR1669 are adopted. It is polished to a surface roughness Ra corresponding to that grade. As the grade increases, the surface roughness R increases. A mirror finish is applied to a surface with a thickness of 0.01 μm or less.

[0041] Next, the manufacturing of metal plate setters, materials for ceramic balls, and ceramic balls. The method will be explained. Metal plate setter, material for ceramic balls, and ceramic The ball only needs to have the above configuration, but there are ways to improve the yield. The explanation is as follows.

[0042] This document describes the manufacturing method of a metal plate setter. The metal plate used is SUS304 (18-8 stainless steel). This explains how to use a metal sheet setter made of stainless steel. When degreasing using a batch furnace, The metal plate setters, on which the molded bodies are placed, are stacked in multiple layers in a shelf-like configuration. The cutter is, for example, a rectangular plate shape. A cone on a rectangular metal plate up to a few millimeters thick. Bending is performed to form a recessed shape. The bending is done using a press machine with upper and lower dies. Using this tool, a metal plate is sandwiched between the two and pressed to form a predetermined recess. In the bending process, the spring Because ringback occurs, the bending angle should be set taking springback into consideration. The metal plate setter can also be made to form ribs to ensure strength. Furthermore, as shown in Figure 7 When creating a through hole, use tools such as machine tools or drills to form the through hole. At this time, it is also possible to form the through hole first and then perform the bending process. Through holes can also be formed in areas other than the recessed areas to enhance the gas venting effect. When applying Lamix coating, ceramic is applied to the surface of the processed metal plate by thermal spraying or other means. Coat the casing.

[0043] Next, a method for manufacturing materials for ceramic balls will be described. First, the method for preparing molded bodies of ceramic ball materials will be described using silicon nitride. When aluminum oxide or zirconium oxide is used as the main component (50% by mass or more), replace silicon nitride and apply the respective manufacturing conditions. Furthermore, in the embodiments of the present invention, as a method for obtaining molded bodies... one While axial compression molding is mentioned, the molding method is not limited to this. For example, rolling granulation may also be used as the molding method.

[0044] First, silicon nitride powder, which is the raw material, is mixed with an appropriate amount of sintering aid powder, additives, solvent, and binder. Add and mix, crush, and granulate using a spray dryer. This process produces raw material powder. The final granulated powder is prepared. The total amount of silicon nitride powder and sintering aid powder is set to 100% by mass. In this case, it is preferable to have silicon nitride powder at 85% by mass or more. Furthermore, additives such as plasticizers are used. Yes, it exists. The solvent is water or an organic solvent. Examples of organic solvents include alcohols, ketones, and benzyl sulfate. There are various components. Furthermore, the binder is an organic substance. The amount of binder added is silicon nitride powder and sintered material. When the total amount of auxiliary powder is 100 parts by mass, it is preferable that the amount be between 3 parts by mass and 20 parts by mass. It seems that by adjusting the amount of binder, the shape of the molded body during uniaxial compression molding and CIP can be controlled. The shape retention and density uniformity can be adjusted. Furthermore, by forming it into granular powder, silicon nitride The powder and the sintering aid powder can be mixed uniformly.

[0045] Next, uniaxial pressure molding is performed using granulated powder. Uniaxial pressure molding is performed using the upper punch shown in Figure 2 and One example is a mold molding method using a lower punch. The shape of the molded body is adjusted according to the shape of the mold. This is possible by making the inside of the upper punch and the lower punch hemispherical. A spherical molded body can be obtained. The shape of the molded body obtained by uniaxial pressure molding is shown in Figure 1. The diagram shows a spherical shape having a spherical portion 2 and a strip-shaped portion 3.

[0046] Next, the molded body is subjected to a CIP (Cleaning In-Place) treatment. A rubber mold is used during the CIP treatment. The molded body is filled into the holes in the rubber mold. Since the molded body is formed using granulated powder, CI When isotropic pressure is applied to the molded body through P treatment, the granulated powder is crushed, suppressing density variations. This can be done. By using granulated powder in the molding of the molded body, silicon nitride powder and sintering aid powder can be combined. This allows for homogeneous dispersion while suppressing density variations. Furthermore, when performing CIP processing... This method involves directly placing granulated powder into a CIP rubber mold without performing the aforementioned uniaxial pressure molding, thereby shaping the molded body. It can also be adjusted.

[0047] Furthermore, the pressure used in CIP molding is preferably higher than the press pressure used in uniaxial compression molding. Furthermore, the conditions for CIP treatment are preferably within the pressure range of 30 MPa to 300 MPa. It seems that when the pressure is within this range, it reduces the density variation of the molded product after CIP treatment. It is possible.

[0048] Next, a degreasing process is performed to remove the molded product after the CIP treatment. This process involves heating the material to a temperature above the decomposition temperature of the organic components to remove them. In the degreasing process, the metal sheet is subjected to a degreasing process. The molded body is placed on the setter. Figure 8 shows the degreasing process using the metal plate setter according to this embodiment. Here is an example. A ceramic ball base is placed on a metal plate setter 8 and placed in a degreasing furnace 10. It is installed in [location]. The degreasing process may be carried out in a nitrogen atmosphere or an air atmosphere. It can produce fat.

[0049] Next, a sintering process is performed to sinter the degreased body. The degreased body is placed in a sintering furnace and heated to sinter it. The bonding process is carried out. The sintering process is preferably performed at a temperature of 1700°C to 2000°C. It is preferable to carry out the process in a nitrogen atmosphere. Furthermore, the pressure during sintering should be between atmospheric pressure and 300 MPa. It is preferable to perform the procedure within the following range. Note that atmospheric pressure is 0.10133 MPa (= 1 atm). This is the process. After the sintering process, a material for ceramic balls (sintered body) is obtained. The resulting sintered body may be subjected to HIP (Hot Isostatic Pressing) treatment. This process allows us to obtain material for ceramic balls. The material for the ball shall be a ceramic sintered body with a theoretical density of 98% or higher.

[0050] Manufacturing ceramic balls by polishing the material used for ceramic balls. This can be done. A typical example of sphere polishing is surface plate polishing. For example, ceramic The material for the abrasive ball is inserted between two parallel grinding plates. Due to the movement of the grinding plates, One example is processing the material for the Lamix ball into a perfect sphere. The surface of the bearing ball. The roughness is specified in ASFM F2094. The bearing balls are AS depending on the application. Grades conforming to TMF2094, ISO26602, or JISR1669 are adopted. It is polished to a surface roughness Ra corresponding to that grade. As the grade increases, the surface roughness R increases. Some products have a mirror finish with a thickness of 0.01 μm or less.

[0051] (Examples 1-7, Comparative Examples 1-5) Metal plate setters with the recess shapes and inclination angles shown in Table 1 were fabricated. The metal plate setters used in the examples had the shape of a conical recess (Figure 4) and the shape of a conical recess with a hole (Figure 7). The metal plate setters used in the comparative examples had the shape of a flat plate (Figure 6) and the shape of a conical recess (Figure 4). The diameter of the conical recess was set to 0.6 times the diameter of the ceramic ball base. That is, if the diameter of the molded body in Example 1 was 30.5 mm, the diameter of the conical recess was 18.3 mm. The diameter of the through hole was set to 0.3 times the diameter of the conical recess. In Example 6, where a through hole was formed in the shape of Example 1, the diameter of the through hole was 5.5 mm. Also, each dimension and angle is the target value for processing. Note that in Table 1, the shape in Figure 4 is conical, the shape in Figure 6 is flat, and the shape in Figure 7 is conical. hole That's what I decided.

[0052] Next, molded bodies of material for ceramic balls were fabricated. The ceramic powder used as raw material was calcined. Add binding agents, additives, solvents, and binders, mix, crush, and then dry with a spray dryer. Granulation was performed. As shown in Table 1, Examples 1-5 and Comparative Examples 1-3 contained 85% by mass or more silicon nitride. The silicon nitride molded body contains aluminum oxide in 85% by mass or less of the silicon nitride in Example 4 and Comparative Example 4. The above is an aluminum oxide (alumina) molded body, and Example 5 and Comparative Example 5 are zinc oxide. This is a molded article of zirconium oxide (zirconia) containing 85% by mass or more of conium. When the total amount of the main component and sintering aid is 100 parts by mass, the amount of binder added is 3 to 20 parts by mass. The volume was measured in parts. The molded body was press-formed using the aforementioned granulated powder. The press-forming process is shown in Figure 2. The process was carried out by die forming using upper and lower punches in the press forming apparatus shown. Press forming using this method is uniaxial pressure forming. Furthermore, the mold is designed to create a spherical molded body. Therefore, 100 molded bodies of each diameter shown in Table 1 were produced.

[0053] The molded body is placed in a rubber mold and subjected to CIP treatment, and the resulting CIP molded body is placed in a metal plate setter. Examples 1-7 and Comparative Examples 2-5 are metal plate setters with conical recesses, and the spherical portion is recessed. It was installed so as to be in contact with it. In contrast, Comparative Example 1 was installed on a flat metal plate setter. did.

[0054] After degreasing the CIP molded body placed in the metal plate setter by heating at 500°C for 1 hour, Silicon nitride was sintered at 1800°C, while aluminum oxide and zirconium oxide were sintered at 1500°C. The spherical portion of the sintered body is measured, and the surface is visually inspected to check for any changes in the contact surface. The appearance defect rate was calculated for items that exhibited shape defects or peeling defects. Deformation defects are detected by measuring the distance L1 between the contact surface and the vertex of the opposite electrode, and the distance L1 between the opposite electrode and the contact surface. When set to 0, change the values ​​of those whose ratio of L1 to L0, L1 / L0, is 0.99 or less. It was deemed to have a poor shape. For example, in the embodiment, L0 is the distance between the vertices (poles) of the spherical part, and L1 is This is the distance between the point of contact and the opposite point. Therefore, if it is spherical, L0 and L1 are... This can be considered the diameter of the material for Lamix Balls. Also, peeling defects occur when the diameter is approximately 0.5 mm or less. Products with peeling were considered defective. The defect rate for appearance is shown in Table 1.

[0055] [Table 1]

[0056] In the examples, the appearance defect rate was within a favorable range. This was due to the metal sheet setter used. This is because the stress on the material for the ceramic balls was distributed. In contrast, In the comparison, the rate of appearance defects was poor. This was due to the use of flat plates and metal plate sets with angles outside the preferred range. Because a tar was used, stress was concentrated at one point on the spherical surface, causing deformation due to weight and pressure. This is because the ceramic ball material and the metal plate setter reacted together.

[0057] Next, excluding products with cosmetic defects, silicon nitride is processed at a temperature of 1700°C to 1900°C under a nitrogen atmosphere. HIP treatment was performed in air at a pressure of 50 MPa to 200 MPa. Aluminum oxide Zirconium oxide is subjected to a temperature of 1300°C to 1500°C in an argon atmosphere at a pressure of 5 HIP treatment was performed at a pressure between 0 MPa and 200 MPa.

[0058] Examples 1-3 and 6-7 show 1-inch (25.4 mm) ceramic balls after polishing. This is a material for ceramic balls. Example 4 is 1 1 / 16 inch (17.46 This is a ceramic ball material for ceramic balls that are (mm) in size. Example 5 is, Ceramic ball to become a 1" 3 / 4 inch (44.45 mm) ceramic ball These are materials for bearings. All of them can be used as bearing balls.

[0059] According to the embodiments described above, the yield of the ceramic ball material in the degreasing process is It is possible to maintain a high level.

[0060] Although several embodiments of the present invention have been illustrated above, these embodiments are presented as examples only. This is not intended to limit the scope of the invention. These novel embodiments are It can be implemented in various other forms, and without departing from the spirit of the invention, These can be omitted, replaced, or modified. These embodiments are modified versions of the present invention The invention described in the claims and its equivalents are included in the scope and gist of the claims. It is included. Furthermore, the embodiments described above can be implemented in combination with each other. [Explanation of symbols]

[0061] 1…Material for ceramic balls 2...Spherical part 3…band-shaped area 4…Press mold 5... Punching section 6…Metal plate setter 7...Conical recess, 71...Vertex of the recess 8…Flat metal plate setter 9…Hole 10…Degreasing furnace

Claims

1. A metal plate setter used for degreasing materials for ceramic balls, A conical recess is formed in the metal plate setter. The conical recess is characterized by having an inclination angle of 10 degrees or more and 60 degrees or less. A metal plate setter used for degreasing materials for ceramic balls.

2. A metal plate setter for degreasing ceramic ball material according to claim 1, characterized in that a hole is formed at the tip of a conical recess formed on one side of the metal plate setter, which penetrates to the opposite side.

3. A metal plate setter for degreasing ceramic ball materials according to claim 1 or 2, characterized in that the material of the metal plate setter is iron or an iron-based alloy.

4. A metal plate setter for degreasing ceramic ball material according to claim 1 or 2, characterized in that the surface of the metal plate setter is coated with ceramics.

5. The process includes degreasing and sintering a material for ceramic balls using a metal plate setter according to claim 1 or claim 2, A method for manufacturing a ceramic ball material, characterized in that the ceramic ball material after sintering is one of the following: a silicon nitride sintered body, an aluminum oxide sintered body, or a zirconium oxide sintered body.

6. The method for manufacturing a ceramic ball material according to claim 5, characterized in that the outer diameter of the ceramic ball material after sintering is 20 mm or more.

7. A method for producing ceramic balls, characterized by obtaining ceramic balls by polishing the ceramic ball material after sintering as described in claim 5.

8. A method for producing ceramic balls, characterized by obtaining ceramic balls by polishing the ceramic ball material after sintering as described in claim 6.

9. The method for producing ceramic balls according to claim 7, characterized in that the arithmetic surface roughness Ra of the ceramic ball is 0.01 μm or less.

10. The method for producing ceramic balls according to claim 8, characterized in that the arithmetic surface roughness Ra of the ceramic ball is 0.01 μm or less.

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