WO2022065292A1

WO2022065292A1 - Processing device, ceramic sphere, and rolling bearing

Info

Publication number: WO2022065292A1
Application number: PCT/JP2021/034544
Authority: WO
Inventors: 則秀佐藤; 文耶中村
Original assignee: Ntn株式会社
Priority date: 2020-09-24
Filing date: 2021-09-21
Publication date: 2022-03-31
Also published as: JP2022053267A

Abstract

A processing device (1) is provided with a first surface plate (10), a first shaft (12), a second surface plate (20) including a retaining unit (20B), a second shaft (22), a polishing layer (11), and a first elastic member (50). The first surface plate (10) includes a first face (10c) that comes into contact with and retains a green ball (91). The first shaft (12) rotates the first surface plate (10) around an axis α. The second surface plate (20) includes: a second face (20c) that faces the first face (10c), and comes into contact with and retains the green ball (91); and the retaining unit (20B) that extends to protrude in a direction intersecting the second face (20c) and surrounds the green ball (91). The second shaft (22) rotates the second surface plate (20) around an axis β. The polishing layer (11) comes into contact with the green ball (91) to polish the green ball (91). The first elastic member (50) is arranged on an inner wall portion of the retaining unit (20B) of the second surface plate (20).

Description

Machining equipment, ceramic balls and rolling bearings

This disclosure relates to processing equipment, especially processing equipment used for polishing green balls. Further, the present invention relates to a ceramic ball formed by the processing apparatus and a rolling bearing.

In general, ceramic balls (ceramic balls) used for rolling elements of rolling bearings are formed by molding raw material powder to produce unsintered ceramic balls, that is, green balls, which are sintered and then sintered. It is manufactured by finishing it into a ceramic ball having a shape close to a true sphere by performing a polishing process. However, since the ceramic sphere has a very high hardness, there is a problem that it takes a long time to process.

On the other hand, green balls before sintering have low hardness and are easy to process, so they can be processed with much higher efficiency than polishing after sintering. Against this background, various proposals have been made regarding the processing of green balls. For example, in JP-A-1-130908 (Patent Document 1), a green ball containing a composition mainly composed of a thermoplastic organic polymer compound as a binder is sandwiched between two opposing surface plates, and a polishing machine is used. Disclosed is a processing method in which abrasive grains and water are dropped onto the surface to perform wet polishing. However, this method has a problem that the composition of the binder is restricted. In addition, this method complicates degreasing and sintering conditions after processing, which causes a problem in mass productivity. Further, Japanese Patent Application Laid-Open No. 2-303767 (Patent Document 2) discloses a processing method in which a green ball is sandwiched between two vertical grindstones and polished. However, this method has a problem of poor mass productivity because it is not possible to process a plurality of green balls at the same time in one device.

On the other hand, in Japanese Patent Application Laid-Open No. 7-314308 (Patent Document 3), a plurality of green balls are sandwiched between a pair of processing surface plates facing each other in a plane, and a plurality of systems along the opposite planes of both processing surface plates are relative to each other. A processing device for polishing a green ball into a shape close to a true sphere while causing the green ball to revolve and rotate in various directions by movement is disclosed. The relative movement of a plurality of systems is, for example, an eccentric rotation of both processing surface plates, a combination of rotation and straight movement, and the like. In this polishing apparatus, the rough surface for polishing in the prepared surface plate is formed by a rough surface constituent member having a grid through which polishing powder can pass, and the rough surface portion on the lower side of the rough surface constituent member. Can be provided with a large number of holes to open on the upper surface. In the polishing method using this processing device, there are no restrictions on the composition of the binder, and a plurality of processes can be performed at the same time.

However, in the processing apparatus for polishing green balls described in JP-A-7-314308, the grids of the rough surface constituent members and the holes provided in the processing platen are formed by the polishing powder generated by polishing the green balls. There is a risk of clogging and reduced polishing efficiency. Therefore, Japanese Patent Application Laid-Open No. 2011-73076 (Patent Document 4) discloses a processing apparatus provided with a polishing powder removing mechanism for efficiently removing polishing powder generated by polishing a green ball from the polishing surface.

Japanese Unexamined Patent Publication No. 1-130908 Japanese Unexamined Patent Publication No. 2-303767 Japanese Unexamined Patent Publication No. 7-314308 Japanese Unexamined Patent Publication No. 2011-73076

When forming a ceramic ball made of silicon nitride, a binder is generally contained for the purpose of increasing the powder density of the green ball and increasing the powder strength. However, the components of the binder may segregate when mixed with the powder constituting the green ball, and may cause cracks and defects due to removal by degreasing. Therefore, a green ball having a low powder strength may be formed without containing a binder. However, if the binder is not contained, cracks are likely to occur during the polishing process of the green ball, which makes the polishing process difficult.

Furthermore, balls for rolling elements are not limited to those made of ceramics, and may be formed by adding silicon and nitrogen to metal. In this case, a method is used in which silicon is put into a metal powder and hardened to form a green ball, which is then polished, and then nitrogen is introduced when the green ball is fired. In this case, the green ball is more easily cracked during the polishing process, which makes the process difficult.

By the way, in Japanese Patent Application Laid-Open No. 2011-73076, a holding layer for holding a green ball is formed on the horizontal plane of the second surface plate arranged vertically above the first surface plate, and the holding layer is formed. Is an elastic member such as rubber or resin. By using an elastic member, it is possible to suppress cracking caused by a plurality of green balls arranged so as to be sandwiched between a second surface plate having a holding portion and a first surface plate directly below the second surface plate and collide with the second surface plate. .. However, in Japanese Patent Application Laid-Open No. 2011-73076, the elastic member is installed only on the horizontal plane facing the first surface plate of the second surface plate. Therefore, cracking may occur when processing a particularly fragile green ball using the processing apparatus of Japanese Patent Application Laid-Open No. 2011-73076. The plurality of green balls charged into the processing apparatus may have significantly different diameters from each other at the initial stage of processing, which exerts a strong force on the green balls. In Japanese Patent Application Laid-Open No. 2011-73076, since the elastic member is not arranged on the inner wall surface of the holding portion of the second surface plate, there is a concern that the green ball colliding with the inner wall surface of the holding portion may break.

This disclosure was made in view of the above issues. An object of the present disclosure is to provide a processing apparatus capable of suppressing cracking during polishing of a plurality of green balls having greatly different diameters in the initial state even when a special construction method not including a binder is used. Is. Further, it is to provide a ceramic ball formed by the processing apparatus and a rolling bearing.

The processing apparatus according to the present disclosure includes a first member, a first shaft, a second member including a holding portion, a second shaft, a polishing layer, and a first elastic member as an elastic member. The first member includes a first surface that holds the green ball by coming into contact with the green ball. The first axis rotates the first member around an axis that intersects the center of the first surface. The second member faces the first surface, includes a second surface that holds the green ball by contacting the green ball, and extends so as to project in a direction intersecting the second surface, the first surface and the second surface. Includes a holding section that surrounds the green ball sandwiched between. The second axis rotates the second member around an axis that intersects the center of the second surface. The polishing layer includes at least one of the first surface and the second surface, and polishes the green ball by contacting with the green ball. The first elastic member is arranged on the inner wall portion of the holding portion of the second member.

According to the above, it is possible to provide a processing device capable of suppressing cracking during polishing of a plurality of green balls having significantly different diameters from each other in the initial state even when a special construction method that does not include a binder is used. Further, it is possible to provide a ceramic ball and a rolling bearing formed by the processing apparatus.

It is a schematic sectional drawing which shows the structure of the processing apparatus which concerns on Embodiment 1. FIG. It is a schematic plan view which shows the structure of a polishing layer. FIG. 3 is a schematic enlarged cross-sectional view showing an example of a fixing mode of each member constituting the second surface plate of FIG. 1. It is schematic cross-sectional view which shows the aspect which the 1st example of the polishing powder removal mechanism was installed in the processing apparatus of FIG. It is a schematic cross-sectional view which shows the mode in which the cleaning member of the 2nd example of the polishing powder removal mechanism is installed in the processing apparatus of FIG. It is a schematic cross-sectional view which shows the mode in which the gas supply member of the 2nd example of the polishing powder removal mechanism is installed in the processing apparatus of FIG. It is a schematic sectional drawing which shows the structure of the processing apparatus which concerns on Embodiment 2. FIG. It is a schematic sectional drawing which shows the structure of the processing apparatus which concerns on Embodiment 3. FIG. It is a schematic sectional drawing which shows the structure of the processing apparatus which concerns on Embodiment 4. FIG. It is a schematic sectional drawing which shows the structure of the processing apparatus which concerns on Embodiment 5. It is a schematic sectional drawing which shows the structure of the processing apparatus which concerns on 1st example of Embodiment 6. It is a schematic sectional drawing which shows the structure of the processing apparatus which concerns on 2nd example of Embodiment 6. It is a schematic sectional drawing which shows the structure of the processing apparatus which concerns on 3rd example of Embodiment 6. It is schematic cross-sectional view which shows an example of the rolling bearing provided with the ceramic ball obtained by sintering the green ball formed by the processing apparatus which concerns on one of Embodiments 1-6.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are given the same reference numbers, and the description thereof will not be repeated.

(Embodiment 1)
First, the processing apparatus used for polishing the green ball in the present embodiment will be described. FIG. 1 is a schematic cross-sectional view showing the structure of the processing apparatus according to the first embodiment. With reference to FIG. 1, the processing apparatus 1 which is a green ball polishing apparatus according to the present embodiment has a first surface plate 10 as a first member, a first shaft 12, and a second member as a second member. It mainly includes a surface plate 20, a second shaft 22, a polishing layer 11, another layer 21, and a first elastic member 50.

In FIG. 1, the first surface plate 10 is arranged below the second surface plate 20. As a result, the second surface plate 20 is arranged directly above the first surface plate 10 so as to face the first surface plate 10 in the vertical direction. However, the present invention is not limited to this, and for example, the second surface plate 20 may be arranged directly below the first surface plate 10 so as to face the first surface plate 10 in the vertical direction.

The first surface plate 10 includes a first surface 10c that holds the green ball 91 by coming into contact with the green ball 91. The first surface 10c is a surface that extends substantially along the left-right direction, that is, the horizontal direction of FIG. The first surface plate 10 includes a first flat plate portion 10A and an outer peripheral portion 10B. Both the first flat plate portion 10A and the outer peripheral portion 10B are formed of a generally known steel material or the like. The first flat plate portion 10A is a main member constituting the first surface plate 10, and its surface extends along the first surface 10c. The first flat plate portion 10A has, for example, a circular surface along the horizontal direction, and has a disk shape having substantially constant dimensions in the vertical direction perpendicular to the surface.

The outer peripheral portion 10B extends from the first flat plate portion 10A so as to project upward in the direction intersecting the first surface 10c. However, the outer peripheral portion 10B is a separate member from the first flat plate portion 10A, and the outer peripheral portion 10B is an annular member in a plan view. The outer peripheral portion 10B has a size that substantially overlaps with the edge portion of the first flat plate portion 10A in a plan view. The outer peripheral portion 10B is provided to prevent the polishing powder or the like described later from the green ball 91 from leaking to the outside of the first surface 10c.

The polishing layer 11 is sandwiched between the first flat plate portion 10A and the outer peripheral portion 10B. The polishing layer 11 polishes the green balls 91 by coming into contact with the green balls 91. For example, the surface of the polishing layer 11 facing the second surface plate 20 on the upper side corresponds to the first surface 10c. In other words, the polishing layer 11 includes the first surface 10c (the polishing layer 11 is arranged in the region including the first surface 10c). FIG. 2 is a schematic plan view showing the structure of the polishing layer. With reference to FIG. 2, the polishing layer 11 may be, for example, a grindstone, but in the present embodiment, the polishing layer 11 is a wire mesh having a grid-like shape of a grid 11a through which the polishing powder can pass. It consists of a grid member of. The green ball 91 to be polished by the processing apparatus 1 is preferably made of powder of any material of ceramics and metal, and the powder may further contain a resin material.

The second surface plate 20 includes, for example, a second surface 20c that faces the first surface 10c in the vertical direction and holds the green ball 91 by coming into contact with the green ball 91. The second surface 20c is a surface that extends substantially along the left-right direction, that is, the horizontal direction in FIG. The second surface plate 20 includes a second flat plate portion 20A and a holding portion 20B. Both the second flat plate portion 20A and the holding portion 20B are formed of a generally known steel material or the like. The second flat plate portion 20A is a main member constituting the second surface plate 20, and its surface extends along the second surface 20c. The second flat plate portion 20A is a main member constituting the second surface plate 20, and its surface extends substantially along the left-right direction, that is, the horizontal direction of FIG. The second flat plate portion 20A has, for example, a circular surface along the horizontal direction, and has a disk shape having substantially constant dimensions in the vertical direction perpendicular to the surface.

The holding portion 20B extends from the second flat plate portion 20A so as to project downward in the direction intersecting the second surface 20c. However, the holding portion 20B is a separate member from the second flat plate portion 20A, and the holding portion 20B is an annular member in a plan view. The holding portion 20B has a size that substantially overlaps with the edge portion of the second flat plate portion 20A in a plan view. Another layer 21 is sandwiched between the second flat plate portion 20A and the holding portion 20B. The surface of the other layer 21 facing the first surface plate 10 on the lower side thereof corresponds to the second surface 20c, for example. The other layer 21 may include the second surface 20c (the other layer 21 may be arranged in the region including the second surface 20c). The other layer 21 may be a polishing layer or may not be a polishing layer. That is, the material of the other layer 21 may or may not be a grindstone. Although not shown, in the present embodiment, the other layer 21 has a grid member such as a wire mesh having a grid-like shape of a grid (corresponding to the grid 11a in FIG. 2) through which the polishing powder can pass. There is.

In FIG. 1, both the first surface 10c and the second surface 20c come into contact with the green ball 91 so as to sandwich the green ball 91. The first surface 10c is included in the polishing layer 11, and the second surface 20c is included in the other layer 21. Further, the green ball 91 to be polished is surrounded by the inside of the holding portion 20B of the second surface plate 20 in a plan view. Therefore, each of the plurality of green balls 91 to be polished is arranged so as to be surrounded by the polishing layer 11, the other layer 21, and the holding portion 20B. The second surface plate 20 can roll and hold the green ball 91 by surrounding the green ball 91 by the second flat plate portion 20A and the holding portion 20B.

At least one of the first surface 10c and the second surface 20c is a polished surface for polishing the green ball 91 by coming into contact with the green ball 91. The first surface 10c is included in the polishing layer 11, and the second surface 20c is included in the other layer 21. Both the first surface 10c and the second surface 20c may be polished surfaces, but only one of them may be a polished surface. The green ball 91 is sandwiched between the first surface 10c and the second surface 20c. Then, the first surface plate 10 and the second surface plate 20 revolve and rotate the green ball 91 by a plurality of relative movements. The relative motion of the plurality of systems of the first surface plate 10 and the second surface plate 20 is, for example, the rotation of the first surface plate 10 and the second surface plate 20 around different axes, or the rotation of one of the surface plates. And the combination of the other surface plate going straight.

FIG. 3 is a schematic enlarged cross-sectional view showing an example of a fixing mode of each member constituting the second surface plate of FIG. 1. With reference to FIGS. 3 and 1, a part of the lower second surface 20c of the other layer 21 contacts the holding portion 20B, and the upper surface of the other layer 21 contacts the second flat plate portion 20A. ing. It is preferable that the second flat plate portion 20A and the holding portion 20B are fixed together with another layer 21 sandwiched between them by, for example, a screw member 30 on which a male screw is formed. The male screw of the screw member 30 may be fitted with a female screw of a nut (not shown) to fix the second flat plate portion 20A and the holding portion 20B. Alternatively, a female screw that fits with the male screw of the screw member 30 may be formed on the second flat plate portion 20A and the holding portion 20B. The portion of the screw member 30 from which the male screw extends is preferably extended so as to penetrate one of the grids 11a. Further, although not shown, in the first surface plate 10, as in FIG. 3, even if the screw member is fitted so as to fix the first flat plate portion 10A, the outer peripheral portion 10B, and the polishing layer 11 between them to each other. good. Further, the first flat plate portion 10A, the outer peripheral portion 10B, and the polishing layer 11 may be fixed to each other by other means without using the screw member as described above.

With reference to FIG. 1 again, the first axis 12 is connected so as to project to the lower side of FIG. 1, which is the side of the first surface plate 10 opposite to the side facing the second surface plate 20. .. A bearing 13 is fitted on the outer peripheral surface of the first shaft 12. The bearing 13 is held by the outer peripheral member 14. With the above configuration, the first surface plate 10 can rotate around the axis α corresponding to the central axis of the first axis 12 in the circumferential direction, for example, as shown by an arrow R1 in FIG. That is, the first axis 12 rotates the first surface plate 10 around the axis α intersecting the center of the first surface 10c. Therefore, the first flat plate portion 10A can also rotate around the first axis 12.

The second axis 22 is connected so as to project upward in FIG. 1, which is the side opposite to the side of the second surface plate 20 facing the first surface plate 10. A bearing 23 is fitted on the outer peripheral surface of the second shaft 22. The bearing 23 is held by the outer peripheral member 24. With the above configuration, the second surface plate 20 can rotate around the axis β corresponding to the central axis of the second axis 22 in the circumferential direction, for example, as shown by an arrow R2 in FIG. That is, the second axis 22 rotates the second surface plate 20 around the axis β intersecting the center of the second surface 20c. Therefore, the second flat plate portion 20A can also rotate around the second shaft 22. Note that the axis β is different from the axis α, and the axis β is parallel to the axis α.

With reference to FIGS. 1 and 3, the processing apparatus 1 of the present embodiment further includes a first elastic member 50 as an elastic member. The first elastic member 50 is made of any of rubber, resin and sponge. The first elastic member 50 is arranged on the inner wall portion of the holding portion 20B of the second surface plate 20. In other words, the inner wall surface 26, which covers at least a part of the inner wall surface of the holding portion 20B having an annular shape in a plan view to hold the green ball 91 so as to surround it, and is a part (outermost surface) of the inner wall portion. The first elastic member 50 is arranged so that the first elastic member 50 is composed of the first elastic member 50. Therefore, the first elastic member 50 is arranged so as to face the green ball 91 surrounded by the second flat plate portion 20A and the holding portion 20B of the second surface plate 20. The first elastic member 50 is attached to the inner wall surface of the holding portion 20B by, for example, double-sided tape. However, the means for joining the first elastic member 50 to the holding portion 20B is arbitrary. The thickness of the first elastic member 50 may be, for example, 5% or more and 30% or less of the thickness of the holding portion 20B in the thickness direction of the holding portion 20B (left-right direction in FIG. 1), and may be 1 mm or more.

In the processing apparatus 1 of FIG. 1, the first diameter D in the plan view of the first flat plate portion 10A has a dimension more than twice the second diameter d in the plan view of the second flat plate portion 20A.

FIG. 4 is a schematic cross-sectional view showing a mode in which the first example of the polishing powder removing mechanism is installed in the processing apparatus of FIG. With reference to FIG. 4, the processing apparatus 1 in the first example of the present embodiment is suctioned as a polishing powder removing mechanism for removing the polishing powder generated by polishing the green ball 91 from the first surface 10c of the polishing layer 11. It includes a member 40. The suction member 40 is arranged on the first surface 10c of the first surface plate 10 so as not to interfere with the second surface plate 20. That is, the suction member 40 has a region (exposed from the second surface plate 20) other than the region facing the second surface plate 20 including the second surface 20c of the first surface 10c (more than the second surface plate 20 in FIG. 4). It is arranged so as to face the first surface 10c in the area on the left side). In the region of the suction member 40 facing the first surface 10c, a plurality of suction holes 41 for sucking the polishing powder are formed. By depressurizing the inside of the suction member 40 with respect to the outside, the polishing powder can be sucked into the inside of the suction member 40 along the arrow a and removed from the first surface 10c which is the polishing surface.

FIG. 5 is a schematic cross-sectional view showing a mode in which the cleaning member of the second example of the polishing powder removing mechanism is installed in the processing apparatus of FIG. FIG. 6 is a schematic cross-sectional view showing a mode in which the gas supply member of the second example of the polishing powder removing mechanism is installed in the processing apparatus of FIG. With reference to FIGS. 5, 6 and 1, the processing apparatus 1 in the second example of the present embodiment is basically the same as that of FIGS. 1 and 4, but the suction member 40 is used as a polishing powder removing mechanism. Instead, the cleaning member 60 and the gas supply member 62 constituting the polishing powder removing mechanism are provided. The cleaning member 60 has a function of cleaning the first surface 10c by supplying an organic solvent as a cleaning liquid to the first surface 10c which is the polishing surface. More specifically, with reference to FIG. 5, the cleaning member 60 is arranged on the first surface 10c so as not to interfere with the second surface plate 20. That is, the cleaning member 60 has a region (exposed from the second surface plate 20) other than the region facing the second surface plate 20 including the second surface 20c of the first surface 10c (more than the second surface plate 20 in FIG. 5). It is arranged so as to face the first surface 10c in the area on the left side). Further, in the region of the cleaning member 60 facing the first surface 10c, a plurality of discharge holes 61 for discharging the organic solvent are formed. Then, the organic solvent is discharged from the discharge hole 61 of the cleaning member 60 toward the first surface 10c of the polishing layer 11 as shown by the arrow b, so that the polishing powder is removed from the first surface 10c of the polishing layer 11. Ru. As the organic solvent, for example, water can be adopted, and a rust preventive agent, a surfactant and the like can be added as needed.

On the other hand, the gas supply member 62 has a function of drying the first surface 10c, which is the polished surface cleaned by the cleaning member 60, particularly when used together with the cleaning member 60 in the processing device 1. More specifically, with reference to FIG. 6, the gas supply member 62 is arranged on the first surface 10c so as not to interfere with the second surface plate 20. That is, the gas supply member 62 has a region (exposed from the second surface plate 20) other than the region facing the second surface plate 20 including the second surface 20c of the first surface 10c (from the second surface plate 20 in FIG. 5). Is arranged so as to face the first surface 10c in the area on the left side). At this time, the gas supply member 62 is arranged on the rear side in the rotation direction of the first surface plate 10 when viewed from the cleaning member 60. Further, in the region of the gas supply member 62 facing the first surface 10c, an injection hole 63 for injecting gas is formed. Then, a gas such as dried air is sprayed from the injection hole 63 of the gas supply member 62 toward the first surface 10c of the polishing layer 11 to dry the first surface 10c wet with a cleaning liquid such as an organic solvent. Can be done.

The processing apparatus 1 in the second example of the present embodiment may include both the cleaning member 60 and the gas supply member 62, but may include only one of the cleaning member 60 and the gas supply member 62. .. Further, the gas supply member 62 is an embodiment in which compressed air is blown toward the first surface 10c of the polishing layer 11 regardless of whether or not it is used together with the cleaning member 60. The gas supply member 62 can blow off and remove the polishing powder adhering to the first surface 10c by supplying compressed air.

Next, a method of polishing the green ball 91 using the processing device 1 will be described. With reference to FIG. 1, first, a plurality of green balls 91 produced by forming the raw material powder into a spherical shape are supplied between the first surface plate 10 and the second surface plate 20 of the processing apparatus 1. At this time, referring to FIG. 1, the first surface plate 10 rotates with the axis α as the rotation axis, and the second surface plate 20 rotates with the axis β as the rotation axis. That is, in the first surface plate 10 and the second surface plate 20, a plurality of systems of relative motion are achieved. As a result, the green ball 91 rotates on its axis and revolves along the inner wall surface 26 of the holding portion 22 of the second surface plate 20.

That is, in the processing apparatus 1 according to the present embodiment, the first surface 10c is a polished surface for polishing the green ball by contacting the green ball 91. Further, the green ball 91 is sandwiched between the first surface 10c and the second surface 20c. Further, the first surface plate 10 and the second surface plate 20 revolve and rotate the green ball 91 by a plurality of systems of relative motion (here, rotational motion around different axes). Therefore, the green ball 91 rotates while changing its rotation axis. Further, since the first surface 10c is a polished surface, the protruding portion of the green ball 91 is preferentially processed by the rotation, and the green ball 91 is polished over the entire surface thereof. As a result, the green ball 91 efficiently approaches a true sphere by polishing by the processing device 1. The second surface 20c may also be a polished surface.

Next, the action and effect of this embodiment will be described.
The processing apparatus 1 according to the present disclosure includes a first surface plate 10 as a first member, a first shaft 12, a second surface plate 20 as a second member including a holding portion 20B, and a second shaft 22. A polishing layer 11 and a first elastic member 50 as an elastic member are provided. The first surface plate 10 includes a first surface 10c that holds the green ball 91 by coming into contact with the green ball 91. The first axis 12 rotates the first surface plate 10 around the axis α intersecting the center of the first surface 10c. The second surface plate 20 faces the first surface 10c, includes a second surface 20c that holds the green ball 91 by contacting the green ball 91, and extends so as to project in a direction intersecting the second surface 20c. The holding portion 20B surrounding the green ball 91 sandwiched between the first surface 10c and the second surface 20c is included. The second axis 22 rotates the second surface plate 20 around the axis β intersecting the center of the second surface 20c. The polishing layer 11 includes at least one of the first surface 10c and the second surface 20c, and polishes the green ball 91 by contacting with the green ball 91. The first elastic member 50 is arranged on the inner wall portion of the holding portion 20B of the second surface plate 20.

A plurality of green balls between the first surface plate 10 as the first member including the first surface 10c and the second surface plate 20 as the second member including the second surface 20c facing the first surface 10c. The 91 is sandwiched, and the relative movement of a plurality of systems along the facing planes of both surface plates is performed. As a result, the green ball 91 can be polished into a shape close to a true sphere. In this embodiment, it is assumed that the first surface 10c is a part of the polishing layer 11 (a layer having a rough surface for polishing). Regarding this, as shown in FIG. 1 and the like, both the first surface 10c and the second surface 20c may be a part of a polishing layer (a layer having a rough surface for polishing processing). Alternatively, only one of the first surface 10c and the second surface 20c may be a part of the polishing layer.

The plurality of green balls 91 are not limited to the region adjacent to the holding portion 20B shown in FIG. 1 and the like, but are actually the central portion of the region surrounded by the polishing layer 11, the other layers 21 and the holding portion 20B in a plan view. Also exists. The green ball 91 in the central portion may collide with the holding portion 20B when moving to the outside, that is, toward the holding portion 20B. Since the green ball 91 is made of a material that is very fragile, cracks and defects may occur at the time of the collision. Therefore, as in the present embodiment, the soft first elastic member 50 is arranged on the inner wall portion (inner wall surface 26) of the holding portion 20B existing on the wall portion surrounding the green ball 91 of the second surface plate 20. As a result, it is possible to prevent the green ball 91 from cracking when the green ball 91 that has moved from the inside to the outside in a plan view collides with the inner wall surface 26.

In the processing apparatus 1, the first surface plate 10 further includes a first flat plate portion 10A that extends along the first surface 10c and is rotatable around the first axis 12. The second surface plate 20 further includes a second flat plate portion 20A that extends along the second surface 20c and is rotatable around the second axis 22. Such a configuration may be used.

A green ball between the two (between the first surface 10c and the second surface 20c) is provided by the first flat plate portion 10A that can rotate around the first axis 12 and the second flat plate portion 20A that can rotate around the second axis 22. The green ball 91 can be polished into a shape close to a true sphere while sandwiching the 91 and causing the green ball 91 to revolve and rotate in various directions.

The processing device 1 further includes a polishing powder removing mechanism (at least one of a suction member 40, a cleaning member 60, and a gas supply member 62) that removes polishing powder generated by polishing the green ball 91 from the polishing layer 11. The polishing powder removing mechanism is arranged so as to face the first surface 10c in a region other than the region of the first surface 10c facing the second surface plate 20. Such a configuration may be used.

Polishing of the green ball 91 produces polishing powder, but especially in the initial stage of processing, the polishing powder is peeled off from the green ball 91 as large particles and adheres to the first surface 10c or the like. If such large particles are left attached to the first surface 10c or the like, the polishing powder will be accumulated in the same place on the first surface 10c as the polishing progresses. The second surface plate 20 rotates around β, but the relative position with respect to the first surface plate 10 in a plan view does not change, so even if the first surface plate 10 rotates, it is the same on the first surface plate 10. This is because the polishing powder is formed at a place (such as directly under the green ball 91). If the polishing of the green ball 91 is continued with a large amount of polishing powder accumulated on the first surface 10c, the surface of the green ball 91 is damaged such as cracks and scratches due to the large polishing powder. Further, the surface of the green ball 91 cannot be polished, and the accuracy of the polishing process is lowered. Therefore, the processing apparatus 1 according to the present embodiment is provided with a suction member 40 constituting a polishing powder removing mechanism, and clogging of the first surface 10c, which is the polishing surface, is suppressed and a decrease in polishing efficiency is suppressed. , The efficient polishing process can be maintained for a long period of time. As described above, the processing device 1 in the present embodiment is a polishing device for the green ball 91 capable of suppressing a decrease in polishing efficiency and efficiently polishing the green ball.

The processing apparatus 1 may have a dimension in which the first diameter D of the first flat plate portion 10A in a plan view is more than twice the second diameter d in a plan view of the second flat plate portion 20A. For example, in the processing apparatus 1 of FIG. 1, when the first surface plate 10 rotates around the axis α, the exposed region of the first surface 10c of the first surface plate 10 that does not overlap with the second surface plate 20 changes. After the polishing powder adheres to the region of the first surface 10c that overlaps with the second surface plate 20, the region is exposed without overlapping with the second surface plate 20 due to the rotation of the first surface plate 10 around the axis α. The polishing powder is removed by the polishing powder removing mechanism. When the first diameter D is sufficiently larger than the second diameter d, that is, the first diameter D is not sufficiently larger than the second diameter d, for example, because D has a dimension more than twice d. In comparison, the first surface 10c is exposed without overlapping with the second surface plate 20, and the ratio of the area and time during which the adhering or accumulated polishing powder can be removed increases. Therefore, the effect of removing the polishing powder by using the polishing powder removing mechanism is enhanced.

The first elastic member 50 in the above processing apparatus 1 may be any of rubber, resin and sponge. As a result, stress concentration applied to the green ball 91 when the green ball 91 collides with the first elastic member 50 can be prevented, and cracking of the green ball 91 can be suppressed.

(Embodiment 2)
FIG. 7 is a schematic cross-sectional view showing the structure of the processing apparatus according to the second embodiment. With reference to FIGS. 7 and 1, the processing apparatus 1 as the green ball polishing apparatus according to the second embodiment basically has the same structure as the processing apparatus 1 according to the first embodiment, and operates in the same manner. At the same time, it has the same effect. However, in the processing apparatus 1 according to the second embodiment, the second elastic member 51 as an elastic member is further arranged between the first flat plate portion 10A and the first surface 10c. In this respect, the present embodiment is different from the case of the first embodiment in which only the first elastic member 50 is provided as the elastic member. The second elastic member 51 is made of the same material as the first elastic member 50. The second elastic member 51 may be attached to the surface of the first flat plate portion 10A on the second surface plate 20 side (upper side in FIG. 7) by, for example, double-sided tape. However, the second elastic member 51 may be simply laid on the surface of the first flat plate portion 10A without using a joining means such as double-sided tape. The thickness of the second elastic member 51 between the first flat plate portion 10A and the first surface 10c is, for example, 5% of the thickness of the first flat plate portion 10A in the thickness direction of the first flat plate portion 10A (vertical direction in FIG. 7). It may be 30% or more and 1 mm or more.

Especially in the initial stage of polishing the green balls 91, the size difference between the plurality of green balls 91 is large. Therefore, especially at the initial stage of processing, the green ball 91 having a relatively large diameter may be easily cracked by directly contacting the hard first flat plate portion 10A. If the soft second elastic member 51 is provided as described above, the stress applied to the green ball 91 due to the green ball 91 colliding with the surface plate on the first surface plate 10 side (lower side in FIG. 7) is concentrated. Can be suppressed and cracking of the green ball 91 can be suppressed. If the second elastic member 51 is provided between the first flat plate portion 10A and the first surface 10c of the first surface plate 10 below the second surface plate 20, as shown in Examples described later, if the second elastic member 51 is provided. In particular, the effect of suppressing the formation of scratches on the green ball 91 is enhanced.

(Embodiment 3)
FIG. 8 is a schematic cross-sectional view showing the structure of the processing apparatus according to the third embodiment. With reference to FIGS. 8 and 1, the processing apparatus 1 as the green ball polishing apparatus according to the third embodiment basically has the same structure as the processing apparatus 1 according to the first embodiment, and operates in the same manner. At the same time, it has the same effect. However, in the processing apparatus 1 according to the third embodiment, the third elastic member 52 as an elastic member is further arranged between the second flat plate portion 20A and the second surface 20c. In this respect, the present embodiment is different from the case of the first embodiment. The third elastic member 52 is made of the same material as the first elastic member 50. The third elastic member 52 may be attached on the surface of the first surface plate 10 side (lower side of FIG. 8) of the second flat plate portion 20A by, for example, double-sided tape, but the joining means thereof is arbitrary. .. The thickness of the third elastic member 52 between the second flat plate portion 20A and the second surface 20c is, for example, 5% of the thickness of the second flat plate portion 20A in the thickness direction of the second flat plate portion 20A (vertical direction in FIG. 8). It may be 30% or more and 1 mm or more.

Especially in the initial stage of polishing the green balls 91, the size difference between the plurality of green balls 91 is large. Therefore, especially at the initial stage of processing, the green ball 91 having a relatively large diameter may be easily cracked by directly contacting the hard second flat plate portion 20A. If the third elastic member 52 is provided as described above, the concentration of stress applied to the green ball 91 is suppressed by the green ball 91 colliding with the surface plate on the second surface plate 20 side (upper side in FIG. 8). Therefore, cracking of the green ball 91 can be suppressed.

(Embodiment 4)
FIG. 9 is a schematic cross-sectional view showing the structure of the processing apparatus according to the fourth embodiment. With reference to FIGS. 9 and 1, the processing apparatus 1 as the green ball polishing apparatus according to the fourth embodiment basically has the same structure as the processing apparatus 1 according to the second and third embodiments, and has the same structure. It works in the same way and has the same effect. However, the processing apparatus 1 in the fourth embodiment has a second elastic member 51 between the first flat plate portion 10A and the first surface 10c shown in FIG. 7, and the second flat plate portion 20A and the second surface shown in FIG. It has both a third

elastic member

52 and 20c. Such a configuration may be used. Elastic members are provided at three locations between the inner wall portion of the holding portion 20B, between the first flat plate portion 10A and the first surface 10c, and between the second flat plate portion 20A and the second surface 20c. It is possible to more reliably suppress a decrease in processing accuracy due to cracking of the green ball 91 or the like.

(Embodiment 5)
FIG. 10 is a schematic cross-sectional view showing the structure of the processing apparatus according to the fifth embodiment. With reference to FIGS. 10 and 1, the processing apparatus 1 as the green ball polishing apparatus according to the fifth embodiment basically has the same structure as the processing apparatus 1 according to the first embodiment, and operates in the same manner. At the same time, it has the same effect. However, in the processing apparatus 1 of the fifth embodiment, the first diameter D in the plan view of the first flat plate portion 10A has a dimension three times as large as the second diameter d in the plan view of the second flat plate portion 20A. That is, the ratio of D to d is larger than that of the first embodiment.

By doing so, as compared with the first embodiment, the ratio of the area and the time during which the polishing powder that is exposed without overlapping with the second surface plate 20 and adhered or accumulated can be removed from the entire first surface 10c is It will increase further. Therefore, the effect of removing the polishing powder by using the polishing powder removing mechanism is further enhanced. Considering the efficiency of removing the polishing powder on the first surface 10c using the polishing powder removing mechanism and the efficiency of processing a larger number of green balls 91 at the same time, the first diameter D is the second diameter d. It is preferably more than 2 times and 3 times or less.

Note that in FIG. 10, the entire second surface plate 20 is contained in the region on the right side of the axis α, which is the center of the plan view of the first surface plate 10. The same embodiment may be used in the first to fourth embodiments. That is, in the first to fourth embodiments, as in the fifth embodiment (FIG. 10), the entire axis including the left end of the second surface plate 20 is the center of the plan view of the first surface plate 10. It may fit in the area on the right side of α.

(Embodiment 6)
In addition to the above, the processing apparatus 1 of the present embodiment has the following modifications in the cross-sectional shape of the first elastic member 50 arranged on the inner wall portion of the holding portion 20B of the second surface plate 20. May have.

FIG. 11 is a schematic cross-sectional view showing the structure of the processing apparatus according to the first example of the sixth embodiment. With reference to FIGS. 11 and 1, the processing apparatus 1 in the first example of the present embodiment basically has the same structure as the processing apparatus 1 in the first embodiment, operates in the same manner, and has the same operation. It has the same effect. However, the processing apparatus 1 in the first example of the sixth embodiment has a configuration in which the first elastic member 50 of the inner wall portion of the holding portion 20B is laminated in a plurality of layers in the thickness direction (left-right direction in FIG. 11). is doing. In FIG. 11, the first elastic member 50A and the first elastic member 50B are laminated as the two layers of the first elastic member 50, but the number of layers may be any number of three or more. By doing so, for example, when the elastic member 50 deteriorates and is replaced, the first elastic member of the innermost layer (the side facing the green ball 91) that has the most chance of coming into contact with the green ball 91 and is likely to deteriorate. Only 50A can be replaced. As a result, the replacement amount of the first elastic member 50 can be reduced, and the replacement cost of the first elastic member 50 can be reduced.

FIG. 12 is a schematic cross-sectional view showing the structure of the processing apparatus according to the second example of the sixth embodiment. With reference to FIGS. 12 and 1, the processing apparatus 1 in the second example of the present embodiment basically has the same structure as the processing apparatus 1 in the first embodiment, operates in the same manner, and has the same operation. It has the same effect. However, in the processing device 1 in the second example of the sixth embodiment, the first elastic member 50 of the inner wall portion of the holding portion 20B is inclined with respect to the vertical direction on the inner wall surface 26 which is the outermost surface thereof. As a result, in FIG. 12, the thickness of the first elastic member 50 (dimensions in the left-right direction along the first surface 10c of FIG. 12) is small on the first surface plate 10 side (lower side of FIG. 12), and the first It is large on the side opposite to the surface plate 10 (upper side in FIG. 12). If the inner wall surface 26 is a flat surface, the first elastic member 50 has a trapezoidal shape in the cross-sectional view of FIG. Contrary to the above, the thickness of the first elastic member 50 may be large on the side of the first surface plate 10 (lower side of FIG. 12) and smaller on the side opposite to the first surface plate 10 (upper side of FIG. 12). .. By doing so, when the green ball 91 collides with the inclined inner wall surface 26 of the first elastic member 50, the collision force per unit area can be reduced. Therefore, the stress applied to the green ball 91 can be further reduced as compared with the case where the inner wall surface 26 extends along the vertical direction, and defects such as cracking of the green ball 91 can be reliably suppressed.

FIG. 13 is a schematic cross-sectional view showing the structure of the processing apparatus according to the third example of the sixth embodiment. With reference to FIGS. 13 and 1, the processing apparatus 1 in the third example of the present embodiment basically has the same structure as the processing apparatus 1 in the first embodiment, operates in the same manner, and has the same operation. It has the same effect. However, in the processing device 1 in the third example of the sixth embodiment, the inner wall surface 26, which is the outermost surface of the first elastic member 50 of the inner wall portion of the holding portion 20B, has a curved surface shape. In FIG. 13, the thickness of the first elastic member 50 in the horizontal direction along the first surface 10c is smaller in the center of the vertical direction in which the first surface 10c and the second surface 20c face each other than the end portion in the vertical direction. It has a curved cross-sectional shape. Therefore, the first elastic member 50 of FIG. 13 has a shape close to a part of the spherical surface so that the surface facing the green ball 91 follows the surface of the green ball 91 close to the spherical surface. However, the present invention is not limited to such an aspect, and for example, although not shown, the first elastic member 50 may have a curved cross-sectional shape so that the thickness in the left-right direction is larger than that of the end portion in the up-down direction at the center in the up-down direction. good. By doing so, when the green ball 91 collides with the curved inner wall surface 26 of the first elastic member 50, the collision force per unit area is reduced as compared with the case where the inner wall surface 26 is a flat surface. Can be done. Therefore, the stress applied to the green ball 91 can be further reduced, and defects such as cracking of the green ball 91 can be reliably suppressed.

FIG. 14 is a schematic cross-sectional view showing an example of a rolling bearing provided with a ceramic ball obtained by sintering a green ball formed by the processing apparatus according to any one of the first to sixth embodiments. With reference to FIG. 14, the rolling bearing 2 is polished using the processing apparatus 1 (as one of (each example) of each of the above embodiments) shown in any of FIGS. 1 and 4 to 13. It is a ball bearing provided with a ceramic ball 4 which is a sintered body obtained by sintering the green ball 91 as a rolling element. In the rolling bearing 2 of FIG. 14, the rolling bearing of FIG. 14 is a radial ball bearing, but it may be a thrust ball bearing. Further, the rolling bearing (radial ball bearing) may be a deep groove ball bearing, but may be either an angular contact ball bearing or a self-aligning ball bearing.

The rolling bearing 2 of FIG. 14 includes an outer ring 3A and an inner ring 3B. The plurality of ceramic spheres 4 roll between the outer ring 3A and the inner ring 3B. The plurality of ceramic spheres 4 are arranged by the cage 5 so as to have an interval in the circumferential direction.

It is basically the same as the second embodiment, but using a processing apparatus in which only the second elastic member 51 on the first flat plate portion 10A is provided and the holding portion 20B is not provided with the first elastic member 50. An experiment on the polishing process of the green ball 91 was conducted. Table 1 below shows the types (materials) of the green balls 91 used in the processing experiment and the presence or absence of a binder.

In Table 1, the material of the green ball is described as "ceramics" because it is a solidified silicon nitride-based ceramic powder. The material of the green ball is described as "metal" because it is made by putting silicon powder into copper-iron powder and hardening it. No. 1 to 8 are groups having 10 green balls 91 each, and 10 green balls 91 were thrown between the first surface 10c and the second surface 20c in FIG. 7 and processed at the same time. No. 1 and No. The two green balls are the same, but the same test was performed twice with them. No. 3 and No. 4, No. 5 and No. 6, No. 7 and No. The same applies to 8. No. 1 to No. In all of 8, the error in the diameter of each green ball was ± 20 μm.

The rotation speed of the first surface plate 10 during polishing was 10 rpm, and the rotation speed of the second surface plate 20 was 250 rpm. The lattice 11a (see FIG. 2) of the polishing layer 11 and the other layers 21 had an opening of 50 μm or more and 350 μm or less. Processing was continued until the green balls 91 had the desired dimensions.

The "dent" in Table 1 means a chipping or peeling larger than the roughness due to the transfer of the grid 11a (see FIG. 2) to the green ball. The "normal surface plate" is basically the same as the processing apparatus of the present embodiment, but none of the above-mentioned second elastic member 51, first elastic member 50, and third elastic member 52 is provided. The test result when the processing equipment equipped with the plate is used is shown. The "elastic body surface plate" indicates a test result when a processing apparatus having a second elastic member 51 is used as described above. From Table 1, by providing the soft elastic member, it is possible to suppress the application of strong stress to the green ball 91 regardless of the presence or absence of the binder. For this reason, it was found that, for example, even when a special construction method that does not include a binder in the green ball is used from the viewpoint of suppressing segregation of powder, defects such as cracks or dents during polishing can be suppressed.

The features described in each of the above-described embodiments (each example included in the above) may be applied so as to be appropriately combined within a technically consistent range. For example, at least one of the polishing powder removing mechanisms of FIGS. 4 to 6 may be used for each of FIGS. 11 to 13, and the second elastic member 51 and the second elastic member 51 and FIG. 3 Elastic member 52 may be added.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope of the claims.

1 Processing equipment, 2 Rolling bearings, 3A outer ring, 3B inner ring, 4 ceramic balls, 5 cage, 10 1st surface plate, 10A 1st flat plate part, 10B outer peripheral part, 10c 1st surface, 11 polishing layer, 11a lattice , 12 1st axis, 13, 23 bearing, 14, 24 outer peripheral member, 20 2nd surface plate, 20A 2nd flat plate part, 20B holding part, 20c 2nd surface, 21 other layers, 22 2nd axis, 26 inside Wall surface, 30 screw member, 40 suction member, 41 suction hole, 50, 50A, 50B first elastic member, 51 second elastic member, 52 third elastic member, 60 cleaning member, 61 discharge hole, 62 gas supply member, 63 Injection hole, 91 green ball.

Claims

A first member including a first surface that holds the green ball by coming into contact with the green ball.
A first axis that rotates the first member around an axis that intersects the center of the first surface, and
A second surface facing the first surface and holding the green ball by contacting the green ball is included, and the first surface and the first surface extend so as to project in a direction intersecting the second surface. A second member including a holding portion that surrounds the green ball sandwiched between the two surfaces, and
A second axis that rotates the second member around an axis that intersects the center of the second surface, and
A polishing layer comprising at least one of the first surface and the second surface and polishing the green ball by contacting with the green ball.
With a first elastic member as an elastic member,
The first elastic member is a processing device arranged on the inner wall portion of the holding portion of the second member.
The first member further includes a first flat plate portion that extends along the first surface and is rotatable around the first axis.
The processing apparatus according to claim 1, wherein the second member further includes a second flat plate portion that extends along the second surface and is rotatable around the second axis.
The processing apparatus according to claim 2, wherein a second elastic member as the elastic member is arranged between the first flat plate portion and the first surface.
The processing apparatus according to claim 2 or 3, wherein a third elastic member as the elastic member is arranged between the second flat plate portion and the second surface.
The processing apparatus according to any one of claims 2 to 4, wherein the first diameter in the plan view of the first flat plate portion has a dimension more than twice the second diameter in the plan view of the second flat plate portion. ..
Further provided with a polishing powder removing mechanism for removing the polishing powder generated by polishing the green ball from the polishing layer.
The one according to any one of claims 1 to 5, wherein the polishing powder removing mechanism is arranged so as to face the first surface in a region other than the region facing the second member on the first surface. Processing equipment.
The processing apparatus according to any one of claims 1 to 6, wherein the elastic member is any of rubber, resin and sponge.
A ceramic ball obtained by sintering the green ball polished by using the processing apparatus according to any one of claims 1 to 7.
A rolling bearing provided with the ceramic ball according to claim 8.