Ceramic ball storage tray and ceramic ball storage method using the same

Abstract

A ceramic ball storage tray has a storage portion that stores ceramic balls. The storage portion of the ceramic ball storage tray has a convex portion in which the center of the bottom surface portion of the storage portion is hollow. Furthermore, the height of the outer peripheral surface of the convex portion is in a range of 0.05 or more and 0.30 or less with respect to the diameter of the ceramic balls. The height of the storage portion is preferably in a range of 1.05 or more and 2.00 or less with respect to the diameter of the ceramic balls. Furthermore, the height of the inner peripheral surface of the convex portion is preferably in a range of 0.01 or more and 0.10 or less with respect to the diameter of the ceramic balls.

Description

Technical Field

[0001] The embodiments described later relate to a ceramic ball storage tray and a method for storing ceramic balls using the tray. Background Technology

[0002] Ceramic balls are used in bearings and other fields. Various materials such as silicon nitride, alumina, and zirconium oxide are used in ceramics. For example, Japanese Patent No. 5487099 (Patent Document 1) discloses bearing balls made of sintered silicon nitride. Even balls with a diameter of approximately 20 mm, the ceramic balls in Patent Document 1 exhibit excellent wear resistance.

[0003] Bearings have evolved into structures with multiple bearing balls positioned between an outer ring and an inner ring. That is, to manufacture a single bearing, multiple bearing balls are required. This necessitates the handling of these multiple ceramic balls.

[0004] For example, Japanese Patent Application Publication No. 2004-18050 (Patent Document 2) discloses a paper container for storing bearing balls. Patent Document 2 uses a container made of thick paper obtained by stacking at least two pieces of corrugated paper with an inner lining layer. Patent Document 2 shows that the paper container will not break even when storing multiple bearing balls.

[0005] Existing technical documents Patent documents Patent Document 1: Japanese Patent No. 5487099 Patent Document 2: Japanese Patent Application Publication No. 2004-18050 Patent Document 3: Japanese Patent No. 4761613 Summary of the Invention

[0006] The problem that the invention aims to solve When using the container described in Patent Document 2 to transport multiple bearing balls, all the bearing balls are stored together inside the container. If multiple bearing balls are stored in one container, problems arise such as the balls contacting each other during transport, causing cracking and breakage. Furthermore, ceramic bearing balls are ground into spheres. Before grinding, they are ceramic balls with strip-shaped portions. For example, Japanese Patent No. 4761613 (Patent Document 3) discloses ceramic balls with strip-shaped portions. If multiple ceramic balls with strip-shaped portions are placed in one container, many cracks and breakages occur because the strip-shaped portions are easily damaged when they collide with each other.

[0007] The problem to be solved by the ceramic ball storage tray and the method for storing ceramic balls using the same according to the embodiments is to reduce the breakage of ceramic balls stored in the ceramic ball storage tray.

[0008] Methods for solving problems The ceramic ball storage tray according to the embodiment has a storage portion for storing ceramic balls. The storage portion of the ceramic ball storage tray has a convex portion formed by hollowing out the center of the bottom surface of the storage portion. Furthermore, the height of the outer peripheral surface of the convex portion is in the range of 0.05 to 0.30 mm relative to the diameter of the ceramic ball. Attached Figure Description

[0009] Figure 1 This is a top view showing an example of a ceramic ball storage tray according to an embodiment.

[0010] Figure 2 In the diagram, (A) is a side view showing an example of a ceramic ball storage tray according to the embodiment, (B) is a BB cross-sectional view showing an example of a ceramic ball storage tray according to the embodiment, and (C) is a CC cross-sectional view showing an example of a ceramic ball storage tray according to the embodiment.

[0011] Figure 3 This is an enlarged view of the BB cross section of the storage portion of the ceramic ball storage tray according to the embodiment.

[0012] Figure 4 This is an enlarged view of the BB cross section of the storage part, showing the ceramic ball storage tray of the embodiment being stacked vertically. Detailed Implementation

[0013] The following describes in detail, with reference to the accompanying drawings, the implementation method of the ceramic ball storage tray and the method of storing ceramic balls using the tray.

[0014] The ceramic ball storage tray according to the embodiment has a storage portion for storing ceramic balls. The storage portion of the ceramic ball storage tray has a convex portion formed by hollowing out the center of the bottom surface of the storage portion. Furthermore, the height of the outer peripheral surface of the convex portion is in the range of 0.05 to 0.30 mm relative to the diameter of the ceramic ball.

[0015] Figure 1 This is a top view illustrating an example of a ceramic ball storage tray according to the embodiment. Furthermore, Figure 2 (A) is a side view showing an example of a ceramic ball storage tray according to the embodiment. Furthermore, Figure 2 (B) is a cross-sectional view of BB showing an example of a ceramic ball storage tray according to the embodiment. Figure 2 (C) is a cross-sectional view showing an example of a ceramic ball storage tray according to the embodiment. Figure 3 This is an enlarged view of the BB cross section of the storage portion of the ceramic ball storage tray according to the embodiment. Figure 4This is an enlarged view of the BB cross section of the storage part, showing the ceramic ball storage tray of the embodiment being stacked vertically.

[0016] In the diagram, symbol 1 represents a ceramic ball storage tray, symbol 2 represents the storage section, symbol 3 represents a ceramic ball, symbol 4 represents a protrusion, symbol 5 represents the height of the outer circumference of protrusion 4, symbol 6 represents the height of the inner circumference of protrusion 4, symbol 8 represents the height of storage section 2, symbol 9 represents the diameter of the outer circumference of protrusion 4, symbol 10 represents the diameter of the inner circumference of protrusion 4, symbol 11 represents the bottom section, symbol 12 represents the periphery of storage section 2, symbol 13 represents the diameter of storage section 2, and symbol 14 represents the recess of the periphery 12. Figure 1 The example shown is a ceramic ball storage tray 1 with 15 storage sections 2. The tray 1 is not limited to this; the number of storage sections 2 can be increased or decreased. Furthermore, in... Figure 1 The example shown depicts a ceramic ball storage tray 1 with 3 vertically x 5 horizontally arranged storage sections; this configuration can be adjusted as needed. Furthermore, the ceramic ball storage tray 1 is sometimes referred to as storage tray 1 or tray 1. Additionally, the ceramic balls 3 are sometimes simply referred to as balls 3. It should be noted that in... Figure 1 The image shows the state in which the storage section 2 in the two columns on the right contains ceramic balls 3.

[0017] The storage tray 1 has a storage section 2. The storage section 2 can hold ceramic balls 3. The storage section 2 has a convex part 4 formed by the central part of the bottom surface 11 being hollow. The bottom surface 11 of the storage section 2 prevents the ceramic balls 3 from falling out. In addition, the opposite side of the bottom surface 11 (i.e., the top side) is made into an opening in a way that makes it easy to hold the ceramic balls 3.

[0018] The protrusion 4 on the bottom surface 11 of the storage section 2 has a shape that convexes downwards from the bottom surface 11. By having the protrusion 4, it is possible to absorb the impact when transporting the tray 1 (i.e., when transporting the ceramic balls 3). Furthermore, as will be described later, by having the protrusion 4 in the storage section 2, it is possible to prevent adjacent ceramic balls 3 from directly contacting each other when the storage tray 1 is stacked vertically. Moreover, the protrusion 4 is preferably a hollow cylinder formed by hollowing the center of the bottom surface 11. By making the protrusion 4 a hollow cylinder, its strength can be improved. Hereinafter, the case where the protrusion 4 is a hollow cylinder that is circular when viewed from above will be described, but this is not a limitation. For example, the protrusion 4 may also be polygonal when viewed from above.

[0019] Furthermore, the diameter of ceramic ball 3 is referred to as the ball diameter. Ceramic ball 3 can also be a ceramic ball with a strip-shaped portion. If the ceramic ball is manufactured using a mold, it becomes a ceramic ball with a strip-shaped portion. By grinding the ceramic ball with the strip-shaped portion, it becomes a perfectly spherical ceramic ball. The storage tray 1 is designed to hold either a perfectly spherical ceramic ball or a ceramic ball with a strip-shaped portion. In other words, ceramic ball 3 includes both perfectly spherical and strip-shaped shapes. Additionally, the ceramic ball before grinding is sometimes referred to as a raw material ball.

[0020] Furthermore, the diameter of the sphere is the maximum diameter of the ceramic sphere 3. If the ceramic sphere 3 is perfectly spherical, the maximum diameter can be any diameter. When the ceramic sphere 3 has a strip-shaped portion, the diagonal of the strip-shaped portion becomes the maximum diameter.

[0021] (The height of the outer circumferential surface and the height of the inner circumferential surface of the convex part) Furthermore, since the protrusion 4 is a hollow convex shape, it has an outer peripheral surface 41 and an inner peripheral surface 42 that stand vertically along the height direction. The height of the outer peripheral surface 41 is set to 5, and the height of the inner peripheral surface 42 is set to 6. Sometimes the height 5 of the outer peripheral surface 41 of the protrusion 4 is also referred to as the outer peripheral height 5. Sometimes the height 6 of the inner peripheral surface 42 of the protrusion 4 is also referred to as the inner peripheral height 6. In order to hold the ceramic ball 3 contained therein on the top side of the inner peripheral surface 42, the height 6 of the inner peripheral surface 42 is preferably lower than the height 5 of the outer peripheral surface 41.

[0022] For example, the height 5 of the outer peripheral surface 41 of the protrusion 4 relative to the diameter of the ball, i.e., "the height 5 of the outer peripheral surface of the protrusion / the diameter of the ball", is preferably within the range of 0.05 to 0.30. If the "height 5 of the outer peripheral surface / the diameter of the ball" is within the range of 0.05 to 0.30, then when multiple storage trays 1 are stacked vertically, it is possible to prevent adjacent ceramic balls 3 from directly contacting each other. In addition, it is possible to prevent the ceramic balls 3 from being damaged due to vibration during the handling of the trays 1.

[0023] If the ratio of "outer perimeter height 5 / ball diameter" is less than 0.05, the effect of providing the protrusion 4 will not be achieved. Furthermore, if the ratio exceeds 0.30, the protrusion 4 becomes too high. If the protrusion 4 is high, the stability when the trays 1 are stacked vertically may decrease. Therefore, the ratio of "outer perimeter height 5 / ball diameter" is preferably between 0.05 and 0.30, more preferably between 0.10 and 0.25.

[0024] Furthermore, the height 6 of the inner circumferential surface 42 of the protrusion 4 relative to the diameter of the ceramic ball 3, i.e., "inner circumferential height 6 of the protrusion / diameter of the ball", is preferably within the range of 0.01 or more and 0.10 or less. Additionally, the height 6 of the inner circumferential surface 42 is preferably lower than the height 5 of the outer circumferential surface 41. The inner circumferential height 6 of the protrusion 4 is the height of the inner circumferential side of the hollow protrusion 4. By ensuring that "inner circumferential height 6 of the protrusion / diameter of the ball" is within the range of 0.01 or more and 0.10 or less, the ceramic ball 3 stored in the lower tray 1 can be held in place by the inner circumferential side of the protrusion 4 when multiple trays 1 are stacked vertically. Even when multiple trays 1 are stacked and transported, movement of the stored ceramic ball 3 can be suppressed. Therefore, breakage of the ceramic ball 3 during transport of the trays 1 can be prevented.

[0025] If the ratio of "inner circumference height 6 of the protrusion / ball diameter" is less than 0.01, the inner circumference height 6 of the protrusion 4 becomes smaller. When multiple trays 1 are stacked vertically, the likelihood of the bottom surface 11 of the storage portion 2 of the upper tray 1 directly contacting the ceramic ball 3 of the lower tray 1 increases. If the area of ​​direct contact between the bottom surfaces of the trays 1 increases, the stress applied to the ceramic ball 3 increases, and the likelihood of breakage increases. Furthermore, if the ratio of "inner circumference height 6 of the protrusion / ball diameter" exceeds 0.10, the protrusion 4 may become too high.

[0026] (Height of storage section 2) Furthermore, the height of the storage section 2 relative to the diameter of the ceramic ball 3, i.e., "height 8 of the storage section / diameter of the ball", is preferably in the range of 1.05 or more and 2.00 or less. The height 8 of the storage section 2 is the length from the bottom part 11 of the storage section 2 to the opening on the opposite side.

[0027] First, draw a vertical line from the center of the bottom surface 11 of the storage section 2. Next, draw a horizontal line (the orthogonal line of the vertical line) from end to end of the opening of the storage section 2. The length from the center of the bottom surface 11 of the storage section 2 to the intersection of the vertical line and the horizontal line is set as the height 8 of the storage section 2.

[0028] If the ratio of the height of the storage section (8) to the diameter of the ball is set to a range of 1.05 to 2.00, excessive movement of the ceramic ball 3 during pallet 1 transport can be suppressed. Therefore, breakage of the ceramic ball 3 during pallet 1 transport can be prevented. Furthermore, even ceramic balls 3 with strip-shaped sections can be prevented from breaking.

[0029] If the ratio of "height of the storage section 8 / diameter of the ball" is less than 1.05, the protrusion 4 of the upper tray 1 may exert excessive stress on the ceramic ball 3 stored in the lower tray 1 when multiple trays 1 are stacked vertically. Furthermore, if the ratio of "height of the storage section 8 / diameter of the ball" exceeds 2.00, the effect of suppressing excessive movement of the ceramic ball 3 during transport may be reduced, even when multiple trays 1 are stacked vertically. Therefore, the ratio of "height of the storage section 8 / diameter of the ball" is preferably between 1.05 and 2.00, more preferably between 1.08 and 1.60.

[0030] (Diameter of storage section 2) Furthermore, the diameter 13 of the storage section 2 relative to the diameter of the ceramic ball 3, i.e., the ratio of "diameter 13 of the storage section / diameter of the ball", is preferably within the range of 1.05 or more and 1.70 or less. If the ratio of "diameter 13 of the storage section / diameter of the ball" is less than 1.05, the ball 3 may become difficult to insert during storage. Furthermore, if the ratio of "diameter of the storage section / diameter of the ball" exceeds 1.70, the ball 3 may move excessively when the tray 1 is being moved.

[0031] Figure 4 The diagram shows an example of stacking storage trays 1. When multiple storage trays 1 are stacked vertically, the protrusion 4 of the upper tray 1 presses down on the ball stored in the lower tray 1. This suppresses movement of the ball 3 when the trays 1 are being moved.

[0032] Furthermore, the outer circumferential height 5 of the protrusion 4 is preferably greater than the inner circumferential height 6 of the protrusion 4. The fact that the outer circumferential height 5 of the protrusion 4 is greater than the inner circumferential height 6 indicates that the bottom surface 11 of the storage portion 2 has a stepped difference. This allows a ceramic ball 3 to be supported at multiple locations. As a result, movement of the ceramic ball 3 can be suppressed when transporting the tray 1. Furthermore, the outer circumferential height 5 of the protrusion 4 is preferably 3 mm or more. By setting the outer circumferential height 5 of the protrusion 4 to 3 mm or more, it becomes easier to form a stepped difference on the bottom surface 11 of the storage portion 2. Furthermore, when multiple trays 1 are stacked vertically, the protrusion 4 plays a role in preventing misalignment. Furthermore, the inner circumferential surface of the storage portion 2 can take various shapes, such as a spherical shape or a stepped shape. For example, the inner circumferential surface of the storage portion 2 can be made into a spherical shape, and the protrusion 4 can be made hollow. The hollow portion becomes a stepped difference. Furthermore, by making the protrusion 4 hollow, the cushioning effect on the ceramic ball 3 when multiple trays 1 are stacked vertically can be improved. In addition, the tray 1 can be made lighter.

[0033] (The diameter of the outer circumferential surface 41 and the diameter of the inner circumferential surface 42) The diameter 9 of the outer peripheral surface 41 of the protrusion 4, relative to the diameter of the ceramic ball 3 (i.e., "outer peripheral diameter 9 of the protrusion / diameter of the ball"), is preferably in the range of 0.3 or more and 0.8 or less. Furthermore, the diameter 10 of the inner peripheral surface 42 of the protrusion 4, relative to the diameter of the ceramic ball 3 (i.e., "inner peripheral diameter 10 of the protrusion / diameter of the ball"), is preferably in the range of 0.1 or more and 0.6 or less. It should be noted that the inner peripheral diameter 10 is naturally smaller than the outer peripheral diameter 9. The outer peripheral diameter 9 of the protrusion 4 is set as the outer diameter based on the front end (i.e., the lower end) of the protrusion 4. Furthermore, the inner peripheral diameter 10 of the protrusion 4 is set as the inner diameter based on the front end (i.e., the lower end) of the protrusion.

[0034] If the ratio of the outer circumference diameter 9 of the protrusion to the diameter of the ball is between 0.3 and 0.8, then when multiple trays 1 are stacked vertically, the protrusion 4 can hold down the ceramic ball 3 stored in the lower tray 1. Similarly, if the ratio of the inner circumference diameter 10 to the diameter of the ball is between 0.1 and 0.6, then when multiple trays 1 are stacked vertically, the protrusion 4 can hold down the ceramic ball 3 stored in the lower tray 1.

[0035] If the ratio of the outer circumference diameter 9 of the protrusion to the diameter of the ball is less than 0.3, the outer circumference diameter 9 of the protrusion 4 may be too small. If the outer circumference diameter 9 of the protrusion 4 is small, the difference between the outer circumference diameter 9 and the inner circumference diameter 10 may become smaller. If the difference between the outer circumference diameter 9 and the inner circumference diameter 10 becomes smaller, the area of ​​the protrusion 4 that contacts the ceramic ball 3 stored in the lower tray 1 when multiple trays 1 are stacked vertically becomes smaller. During the vibration of transporting the tray 1, the contact between the protrusion 4 and the ceramic ball 3 becomes more intense, which may be a cause of breakage.

[0036] Furthermore, if the ratio of the outer diameter of the protrusion (9 / diameter of the sphere) exceeds 0.8, the outer diameter of the protrusion 4 may become too large. Even if the outer diameter of the protrusion 4 is increased, the above-mentioned effect will not be achieved. In addition, if the ratio of the outer diameter of the protrusion (9 / diameter of the sphere) is less than 0.8, it has the effect of reducing the weight of the storage tray 1.

[0037] On the other hand, if the "inner circumference diameter 10 of the protrusion / diameter of the ball" is in the range of 0.1 or more and 0.6 or less, it is possible to further obtain the effect of pressing down the ceramic ball 3 stored in the lower tray 1 when multiple trays 1 are stacked on top of each other.

[0038] Furthermore, if the ratio of the inner circumference diameter 10 of the protrusion to the diameter of the ball is less than 0.1, the inner circumference diameter 10 may be too small. Furthermore, if the ratio of the inner circumference diameter 10 of the protrusion to the diameter of the ball exceeds 0.6, the width of the protrusion 4 may be too narrow. If the width of the protrusion 4 becomes too narrow, the contact between the protrusion 4 and the ceramic ball 3 housed in the lower tray 1 will become violent when multiple trays 1 are stacked vertically, potentially causing breakage.

[0039] Therefore, it is preferable to satisfy both of the following conditions: the outer circumference diameter of the protrusion (9 / sphere diameter) is 0.3 or more and 0.8 or less, and the inner circumference diameter of the protrusion (10 / sphere diameter) is 0.1 or more and 0.6 or less.

[0040] (Surrounding part 12) A surrounding portion 12 exists around the storage section 2. This surrounding portion 12 connects adjacent storage sections 2 to each other. The surrounding portion 12 can also be a frame that covers the sides of the storage section 2. It should be noted that this surrounding portion 12 can also be located at the ends of multiple storage sections 2 (e.g., at...). Figure 1 A surrounding portion 12 is also provided further outward of the storage portion 2 (upper, lower, and right ends). Furthermore, it is preferable to provide a recess 14 in the surrounding portion 12 around the storage portion 2, extending from the opening side of the tray 1 towards the bottom portion 11. Since it becomes easier to insert a finger or robotic arm holding the ball 3 from the opening of the tray 1 towards the storage portion 2 via the recess 14, the ball 3 can be easily placed in the storage portion 2. Furthermore, since it becomes easier to grasp the ball 3 stored in the storage portion 2 with a finger or robotic arm via the recess 14, the ball 3 stored in the storage portion 2 can be easily removed from the tray 1.

[0041] (Materials for storage tray 1) The storage tray 1 is preferably made of plastic. Plastic is also known as synthetic resin. Plastic is a malleable substance made primarily from polymers derived from petroleum and other sources. Plastic can be molded and processed by applying heat or pressure. Because plastic can be molded and processed, it is suitable for forming the storage part 2 as described above. Examples of materials for the tray 1 include plastic, rubber, paper, glass, and ceramics. Among these, plastic is suitable from the viewpoint of strength and lightweight. Furthermore, examples of plastics include polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE). Among these, polyethylene terephthalate is preferred because it has good recyclability.

[0042] (Ceramic ball 3) The ceramic ball 3 stored in the storage tray 1 preferably has a diameter of 10 mm or more. That is, the storage part 2 has a size and shape capable of storing ceramic balls 3 with a diameter of 10 mm or more. If the diameter of the ceramic ball 3 increases, the contact area due to vibration during transport of the storage tray 1 also increases. Furthermore, if the diameter of the ceramic ball 3 increases, the weight also gradually increases. If the weight increases, the stress due to impact due to vibration also increases. By using the storage tray 1 according to the embodiment, the effects of vibration during transport can be suppressed. In other words, the storage tray 1 can be said to be an effective tray for storing ceramic balls 3 with a diameter of 10 mm or more. It should be noted that there is no particular upper limit to the diameter of the ceramic ball 3, but it is preferably 100 mm or less. In addition, the storage tray 1 according to the embodiment can also be applied to ceramic balls 3 with a diameter of less than 10 mm.

[0043] Furthermore, the ceramic sphere 3 may be selected from one or more of the following: silicon nitride sintered bodies, silane sintered bodies, alumina sintered bodies, zirconia sintered bodies, and alumina-zirconia sintered bodies. Alumina-zirconia sintered bodies are sintered bodies obtained by mixing alumina and zirconia. For example, silicon nitride sintered bodies may include sintered bodies containing 85% by mass or more silicon nitride.

[0044] The ceramic spheres 3 are preferably silicon nitride sintered bodies. Silicon nitride sintered bodies are more expensive than alumina sintered bodies. If the ceramic spheres 3 are damaged during transport of the pallet 1, the economic loss is significant. Therefore, the storage pallet 1 of the embodiment is preferably suitable for ceramic spheres 3 made of silicon nitride sintered bodies.

[0045] Furthermore, silicon nitride sintered bodies, silane sintered bodies, zirconia sintered bodies, and alumina-zirconia sintered bodies exhibit a three-point flexural strength of 800 MPa or higher. On the other hand, the three-point flexural strength of alumina sintered bodies is approximately 300 to 500 MPa. Even if the ceramic balls 3 stored in the storage tray 1 of the embodiment are low-strength alumina ceramic balls, breakage can be suppressed.

[0046] (Storage method for ceramic ball 3) The ceramic ball 3 is stored using a storage tray 1 as described above. Specifically, the storage process includes: inserting a finger or robotic arm holding the ceramic ball 3 through the opening of the storage tray 1 towards the storage section 2, and placing the ball 3 in the storage section 2 for storage; and stacking multiple storage trays 1 containing the ceramic ball 3 vertically. Next, the ceramic ball 3 is transported in a conveying process with multiple storage trays 1 stacked vertically. The structure of the storage tray 1 helps to prevent damage to the ceramic ball 3 due to vibrations during transport.

[0047] It should be noted that when multiple storage sections 2 are provided in the storage tray 1, the storage tray 1 may not contain ceramic balls 3 in all of the storage sections 2. For example, ceramic balls 3 with strip-shaped sections can be ground to become perfectly spherical ceramic balls 3. Perfectly spherical ceramic balls 3 can be used as bearing balls. Furthermore, multiple bearing balls can be used to assemble a bearing. When the bearing is completed, a transfer process of the tray 1 occurs. It is important to prevent the ceramic balls 3 from breaking during the transfer of the tray 1.

[0048] (Key points of vibration and drop tests) The storage tray 1 described in this embodiment is configured such that multiple storage trays 1 containing balls 3 can be stacked vertically. Because the storage section 2 has the above-described configuration, when multiple storage trays 1 are stacked vertically, adjacent ceramic balls 3 can be prevented from contacting each other. Furthermore, when multiple storage trays 1 are stacked vertically, adjacent ceramic balls 3 can also contact each other via the protrusions 4. If multiple storage trays 1 can be stacked, the tray 1 can be transported efficiently. Moreover, by providing the protrusions 4 as described above, a structure in which the upper and lower trays 1 interlock can be obtained. When multiple trays 1 are stacked and transported, misalignment of the upper and lower trays 1 can be prevented.

[0049] The storage tray 1 described above can prevent the ceramic balls 3 from breaking due to vibration or drops. The performance of the storage tray 1 can be evaluated by vibration and drop tests according to JIS-Z-0200 (2013). It should be noted that JIS-Z-0200 corresponds to ISO 4180.

[0050] Even when subjected to vibration test level 1 and drop test level 1 according to JIS-Z-0200, the ceramic ball 3 can be prevented from breaking. Vibration tests have levels, with level 1 being the most stringent condition. Similarly, drop tests also have levels, with level 1 being the most stringent condition.

[0051] Even when subjected to vibration test level 1 and drop test level 1, the storage tray 1 according to the embodiment does not suffer damage. Furthermore, even when the tray 1 containing the ceramic balls 3 is subjected to vibration test level 1, the breakage rate of the ceramic balls 3 can be set to 0% or more and 1% or less. Similarly, even when the tray 1 containing the ceramic balls 3 is subjected to drop test level 1, the breakage rate of the ceramic balls 3 can be set to 0% or more and 1% or less. Therefore, breakage of the ceramic balls 3 during transport can be suppressed.

[0052] (Example) (Examples 1-10, Comparative Examples 1-4) The storage tray 1 of Examples 1-10 and the storage trays of Comparative Examples 1-4 were prepared as plastic storage trays with a width of 523mm × length of 415mm. A storage section 2 was provided in the storage tray 1 of Examples 1-10. On the other hand, the storage trays of Comparative Examples 1 and 4 did not have a storage section 2, while the storage trays of Comparative Examples 2 and 3 had a storage section outside the area of ​​the storage section 2. The shapes of the stored ceramic balls and the storage sections were set as shown in Table 1.

[0053] Furthermore, the ceramic balls stored in the storage trays according to Examples 1-8 and Comparative Examples 1-3 were ceramic balls made of silicon nitride sintered body. Furthermore, the ceramic balls stored in the storage trays according to Examples 9-10 and Comparative Example 4 were ceramic balls made of alumina sintered body. The silicon nitride sintered body ceramic balls used ceramic balls with a three-point flexural strength of 950 MPa. Furthermore, the alumina ceramic balls used ceramic balls with a three-point flexural strength of 400 MPa.

[0054] Table 1

[0055] Comparative Examples 1 and 4 are containers with a quadrilateral shape of 523mm in width and 415mm in height. Therefore, Comparative Example 1 does not have a storage section.

[0056] Furthermore, Comparative Example 2 is configured the same as Example 1, except that it does not have a protrusion. Additionally, Comparative Example 3 is an example where the outer perimeter height / sphere diameter is 0.5.

[0057] Regarding the storage trays involved in the embodiments and comparative examples, the outer circumferential height of the protrusion / sphere diameter, the inner circumferential height of the protrusion / sphere diameter, the outer circumferential diameter of the protrusion / sphere diameter, the inner circumferential diameter of the protrusion / sphere diameter, the height of the storage portion / sphere diameter, and the number of storage portions in one storage tray are shown in Table 2.

[0058] Table 2

[0059] Ceramic balls are stored in all the storage compartments of the storage trays described in the embodiments and comparative examples. Furthermore, in Comparative Examples 1 and 4, 20 ceramic balls are stored in one storage compartment.

[0060] Vibration and drop tests were conducted on each of the storage trays involved in the embodiments and comparative examples. The tests involved stacking the storage trays containing ceramic balls in three sections along the vertical direction. The three overlapping sections of the storage tray were then bundled together with corrugated cardboard and secured with strapping. The resulting item was used as the test sample. The strapping was secured in two places along the longitudinal direction and two places along the transverse direction.

[0061] The vibration test was conducted according to Level 1 of the random vibration test in JIS-Z-0200 (2013). The vibration frequency was set to 6 Hz, the vibration direction was set to vertical, and the test was conducted for 180 minutes.

[0062] The drop test was conducted according to JIS-Z-0200 (2013) Level 1. The drop height was set to 60 cm. In addition, the drop sequence was set as follows: 2-3-5 corner, 3-5 edge, 2-3 edge, 2-5 edge, 2-3-6 corner, 3-6 edge, 2-6 edge, 5 face, 6 face, 2 face, 3 face, 1 face.

[0063] After the vibration test and the drop test, the ceramic balls were investigated for any damage. Ten samples were prepared for each test.

[0064] The proportion of ceramic balls that broke during vibration and drop tests was taken as the breakage rate (%). The breakage rate (%) was calculated using the following formula.

[0065] Damage rate (%) = (Number of damaged items / Number of items stored in the storage compartment) × 100 The results are shown in Table 3.

[0066] Table 3

[0067] As can be seen from Table 3, no breakage of the ceramic balls was observed when using the storage tray 1 described in Examples 1 to 10. Even the low-strength alumina sintered ceramic balls, as described in the storage tray 1 described in Examples 9 to 10, did not break.

[0068] For square boxes lacking a storage compartment, such as Comparative Examples 1 and 4, the breakage rate is higher. In particular, the breakage rate increases significantly in the case of the low-strength alumina sintered ceramic balls shown in Comparative Example 4. Furthermore, in the case of Comparative Example 2, where there is no protrusion in the storage compartment, the breakage rate is higher when trays are stacked because the protrusion does not hold the balls in place. Moreover, if the protrusion is too high, as in Comparative Example 3, the stress on the balls stored in the lower tray increases when trays are stacked, thus increasing the breakage rate.

[0069] According to at least one embodiment described above, damage such as cracking and breakage of ceramic balls stored in a ceramic ball storage tray can be reduced.

[0070] The above embodiments of the present invention have been illustrated, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways, and various omissions, substitutions, modifications, etc., can be made without departing from the spirit of the invention. These variations of the embodiments are included in the scope and spirit of the invention, and are also included in the scope of the invention described in the claims and its equivalents. Furthermore, the above embodiments can be combined with each other for implementation.

Claims

1. A ceramic ball storage tray, characterized in that, It is a ceramic ball storage tray with a storage section for ceramic balls with a diameter of 10mm or more and less than 100mm. The storage section has a hollow central portion formed by the bottom surface of the storage section, and the convex portion protrudes downward. The ratio of the height of the outer peripheral surface of the protrusion to the diameter of the ceramic ball, i.e., "height of the outer peripheral surface of the protrusion / diameter of the ceramic ball", is within the range of 0.05 to 0.

30. When multiple ceramic balls are stacked on a tray, this prevents adjacent ceramic balls from directly contacting each other. The ratio of the height of the storage section to the diameter of the ceramic ball, i.e., "height of storage section / diameter of ceramic ball", is in the range of 1.05 or more and 2.00 or less.

2. The ceramic ball storage tray according to claim 1, characterized in that, The ratio of the height of the inner circumferential surface of the protrusion to the diameter of the ceramic ball, i.e., "height of the inner circumferential surface of the protrusion / diameter of the ceramic ball", is in the range of 0.01 or more and 0.10 or less.

3. The ceramic ball storage tray according to claim 1, characterized in that, The ratio of the diameter of the outer peripheral surface of the protrusion to the diameter of the ceramic ball, i.e., "diameter of the outer peripheral surface of the protrusion / diameter of the ceramic ball", is in the range of 0.3 or more and 0.8 or less.

4. The ceramic ball storage tray according to claim 1, characterized in that, The ratio of the diameter of the inner circumferential surface of the protrusion to the diameter of the ceramic ball, i.e., "diameter of the inner circumferential surface of the protrusion / diameter of the ceramic ball", is in the range of 0.1 or more and 0.6 or less.

5. The ceramic ball storage tray according to claim 1, characterized in that, The storage section has the size and shape to accommodate ceramic balls with a diameter of 10 mm or more.

6. The ceramic ball storage tray according to claim 1, characterized in that, The height of the outer peripheral surface of the protrusion is 3mm or more.

7. The ceramic ball storage tray according to claim 1, characterized in that, The ceramic ball storage tray is made of plastic.

8. The ceramic ball storage tray according to claim 1, characterized in that, The protrusion is a hollow cylindrical shape formed by hollowing out the center of the bottom surface.

9. The ceramic ball storage tray according to claim 2, characterized in that, The ratio of the diameter of the outer peripheral surface of the protrusion to the diameter of the ceramic ball, i.e., "diameter of the outer peripheral surface of the protrusion / diameter of the ceramic ball", is in the range of 0.3 or more and 0.8 or less. The ratio of the diameter of the inner circumferential surface of the protrusion to the diameter of the ceramic ball, i.e., "diameter of the inner circumferential surface of the protrusion / diameter of the ceramic ball", is in the range of 0.1 or more and 0.6 or less.

10. The ceramic ball storage tray according to claim 9, characterized in that, The storage section has the size and shape to accommodate ceramic balls with a diameter of 10 mm or more.

11. A method for storing ceramic balls, characterized in that, Using any one of the ceramic ball storage trays according to claims 1 to 10, multiple ceramic ball storage trays containing the ceramic balls are stacked one on top of the other.

12. The method for storing ceramic balls according to claim 11, characterized in that, When the multiple ceramic balls are stacked on top of each other on the storage tray, adjacent ceramic balls do not touch each other.

13. The method for storing ceramic balls according to claim 11, characterized in that, When the multiple ceramic balls are stacked on top of each other on the storage tray, adjacent ceramic balls come into contact with each other via the protrusions.

14. The method for storing ceramic balls according to any one of claims 11 to 13, characterized in that, The ceramic balls, each with a strip-shaped portion, are stored in the plurality of ceramic ball storage trays, which are then stacked one on top of the other.

15. The method for storing ceramic balls according to any one of claims 11 to 13, characterized in that, The ceramic balls, made of silicon nitride sintered body, are respectively stored in the plurality of ceramic ball storage trays, and the plurality of ceramic ball storage trays are stacked one on top of the other.

16. The method for storing ceramic balls according to any one of claims 11 to 13, characterized in that, The ceramic balls are transported in a stacked manner, with the multiple ceramic ball storage trays containing the ceramic balls stacked one on top of the other.

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