JP3580577B2 - Ceramic dynamic pressure bearing and method of manufacturing the same - Google Patents

Description

【００５３】
実験例２
次に、上記の製造方法により図１に示すスラスト軸受を製造した。セラミック体１はアルティックにより形成し、動圧発生溝２の深さを変化させた時の性能評価を行った。
【００５４】
結果は表２に示す通りである。表１中、Ｎｏ．１においては、溝深さが浅すぎるため加工時間の制御ができずセラミック体１表面に未加工部分が残ってしまい所定の動圧効果を得ることはできなかった。また、Ｎｏ．７では溝深さが深いため動圧発生溝２の断面が奥に向かって幅が狭くなるテーパ形状となり、かつ隅部に大きなＲ面が発生し、性能評価においても所定の動圧効果を得ることはできなかった。
【００５５】
これに対し、溝深さを２〜３０μｍとしたＮｏ．２〜６については、精度的にも性能的にも何等問題はなく、特に溝深さを２〜２０μｍとしたもの（Ｎｏ．２〜５）は優れた動圧効果を示した。
【００５６】
【表２】

【００５７】
【発明の効果】
以上のように本発明によれば、表面に動圧発生溝を有するセラミック製動圧軸受において、ヤング率が３００ＧＰａ以上、平均結晶粒径が０．５μｍ以上のセラミックスで形成するとともに、動圧発生溝底部の表面粗さ（Ｒａ）を１μｍ以下としたことによって、動圧発生溝のエッジによる相手材の切削摩耗を低減し、かつ潤滑剤を軸受表面に均一に介在させ、摩耗量を低減し、高い信頼性と長寿命化をもたらすことができる。
【００５８】
また本発明によれば、セラミック製動圧軸受の動圧発生溝を形成する際に、フォトレジスト膜の露光・現像を利用してマスキングをすることにより形状の制限を全く受けることなく正確にかつ容易にマスキングを行うことができる。また、この表面にコントロールされた硬質微粒子を噴射することにより、サブミクロンオーダーの加工を実現し、所望の凹溝を有したセラミック製動圧軸受を高精度に量産加工することができる。
【図面の簡単な説明】
【図１】本発明のセラミック製動圧軸受の一例である動圧スラスト軸受けを示し、（ａ）は平面図（ｂ）は（ａ）中のＸ−Ｘ線断面図である。
【図２】本発明のセラミック製動圧軸受の製造方法を説明する図である。
【図３】本発明のセラミック製動圧軸受の製造方法に使用するガラスマスクを示す平面図である。
【図４】本発明のセラミック製動圧軸受の製造方法を説明する図である。
【図５】一般的な動圧軸受装置を示す断面図である。
【符号の説明】
１：セラミック体
２：動圧発生溝
２ａ：底部
３：凸部
４：外周部
２２：動圧スラスト軸受[0001]
[Industrial applications]
The present invention relates to a ceramic dynamic pressure bearing used for supporting a shaft of an electric motor or the like, and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, plain bearings, ball bearings, oil-impregnated bearings, and the like have been generally used as bearing devices. However, in the conventional bearing, various problems have arisen as the product becomes thinner and higher in performance.
[0003]
For example, when the thickness of a spindle motor of a floppy disk drive (FDD) device or the like is to be reduced, it is necessary to shorten the bearing, but as the length is shortened, the shaft runout increases. As a result, there is a problem that the eccentricity of the medium is increased and the reliability of data reading / writing is significantly reduced.
[0004]
As a solution to such a problem, a dynamic pressure bearing in which a dynamic pressure generating groove such as a spiral groove is formed on the surface of a radial bearing and / or a thrust bearing has been developed. This is such that the dynamic pressure generating groove exerts a pumping action on the lubricating fluid with the rotation of the spindle motor, so that the fluid pressure rises to float the shaft, form a fluid film, and rotate without contact. . Further, the eccentricity can be remarkably suppressed by the centering effect by the fluid pressure.
[0005]
As shown in FIG. 5, the configuration of the dynamic pressure bearing includes a shaft 21 and a sleeve 23 supporting the shaft 21. A dynamic pressure generating groove 24a is formed on the outer periphery of the shaft 21 to form a radial bearing portion 24 having rigidity in the radial direction. On the other hand, the dynamic pressure thrust bearing 22 is formed with a spiral dynamic pressure generating groove 22a so as to have thrust rigidity by a pumping action of a lubricating fluid such as oil or gas.
[0006]
Here, an important part is the dynamic pressure thrust bearing 22. For example, in the radial direction of a vertical motor, the outer diameter of the shaft 21 is almost equal to the inner diameter of the sleeve 23, so that there is almost no damage due to contact or peeling of the surface. On the other hand, in the thrust direction, all the thrust forces such as the weight of the rotating portion and the attraction force of the magnet and the stator are applied to the contact portion between the dynamic pressure thrust bearing 22 and the end of the shaft 21. The contact rotation during rotation has an important effect on durability.
[0007]
Conventionally, both the shaft 21 and the dynamic thrust bearing 22 constituting the dynamic pressure bearing use a hardened material such as stainless steel. However, when metal is used, there is a problem in that abrasion easily occurs due to contact between the metals, and when the generated abrasion powder enters the bearing gap, galling occurs. Therefore, it has been considered to form the dynamic pressure thrust bearing 22 and the like with ceramics.
[0008]
What is important in the dynamic pressure bearing is a factor relating to the shape and depth of the dynamic pressure generating groove necessary for pumping a lubricating fluid such as oil or gas. High machining accuracy is required for the shape accuracy and groove depth of the pressure generating groove 22a. As a method of forming the spiral dynamic pressure generating groove 22a, various methods such as (1) chemical etching, (2) shot blast, and (3) laser processing have been proposed.
[0009]
In the case of the dynamic pressure thrust bearing 22 made of a metal such as stainless steel, a desired spiral shape and groove depth are formed by performing a chemical etching process. However, this manufacturing method is required to be improved with respect to the environmental problem of waste liquid treatment after the etching treatment, the problem of processing time (mass productivity), and the like. Further, there is a problem that the metal dynamic pressure thrust bearing 22 is easily worn by sliding at the time of starting and stopping.
[0010]
Therefore, it has been proposed that the dynamic pressure thrust bearing 22 is formed of ceramics and the spiral dynamic pressure generating groove 22a is processed by a shot blast method (Japanese Patent Application Laid-Open Nos. 63-163016 and 2-93115). Etc.).
[0011]
The shot blast method is well known as a manufacturing method for forming a concave groove on the surface of a ceramic member (see JP-A-60-14615, JP-A-62-278313, JP-A-5-58765, etc.). After fabricating a resin mask or a metal mask excluding the desired groove-forming portion and attaching it to the surface of the ceramic body, a shot blasting process is performed to form a groove in a non-masked portion in a short time. Is what you do.
[0012]
[Problems to be solved by the invention]
However, the above-mentioned ceramic dynamic pressure bearing has a problem that it is difficult to stably hold the fluid film, and it is easy to wear by contacting a mating material. In this case, the edge of the dynamic pressure generating groove easily cuts and wears the counterpart material, so that the life is short.
[0013]
Further, in the conventional method of manufacturing a ceramic dynamic pressure bearing, the work of manufacturing a mask having a predetermined spiral shape and the like and the work of attaching the mask to the ceramic surface are extremely complicated. Since patterning of the shape cannot be performed with high accuracy, there is a problem that it is difficult to mass-produce efficiently.
[0014]
Furthermore, in terms of processing accuracy, in order to form a concave groove on the surface of the ceramic body in a short time, it is necessary to keep the blast nozzle close to the surface of the workpiece, and the hard blast nozzle sprayed on the surface of the workpiece. Since the fine particles collide with the surface of the workpiece and are gradually worn away, it has been extremely difficult to stably mass-produce a uniform and highly accurate groove depth.
[0015]
Therefore, instead of shot blasting, there is a method of processing grooves in ceramic dynamic pressure bearings using laser light.However, in this case, processing time is required because laser light is applied along the shape of the dynamic pressure generating grooves. Needless to say, the problem that the desired surface smoothness is difficult to obtain due to the deposition of the molten layer on the processed surface, the problem of cracks due to the increase in the heat-affected layer, and the molten layer that precipitates at the boundary between the processed portion and the unprocessed portion There is a problem that it is necessary to remove the iron.
[0016]
[Means for Solving the Problems]
The present invention relates to a ceramic dynamic pressure bearing having a dynamic pressure generating groove on its surface, comprising a ceramic having a Young's modulus of 300 GPa or more, an average crystal grain size of 0.5 μm or more, and a surface roughness at the bottom of the dynamic pressure generating groove. (Ra) is 1 μm or less. In the present invention, the surface roughness is represented by a center line average roughness (Ra) specified in JIS B0601.
[0017]
Here, the reason why the ceramics having a Young's modulus of 300 GPa or more was used is that the dynamic pressure generating groove formed with high accuracy (groove depth accuracy of about ± 1 μm) due to deformation under applied load when the ceramic pressure is less than 300 GPa. Is not sufficiently stable.
[0018]
The reason why the average crystal grain size of the ceramic is 0.5 μm or more is that if the average crystal grain size is less than 0.5 μm, the edge of the dynamic pressure generating groove becomes too sharp and cutting wear of the mating material increases. In order to maintain excellent mechanical properties, the average crystal grain size is preferably set to 10 μm or less.
[0019]
The reason why the surface roughness (Ra) of the groove bottom of the dynamic pressure generating groove is set to 1 μm or less is that if it exceeds 1 μm, the holding force of a fluid film formed by a lubricant or the like interposed between the dynamic pressure thrust bearing and the mating material. Is reduced, and the dynamic pressure bearing easily comes into contact with the mating material, and the wear proceeds. Further, the flatness of the bottom of the dynamic pressure generating groove is preferably set to 3 μm or less.
[0020]
Further, the present invention provides a method for manufacturing a ceramic dynamic pressure bearing having a dynamic pressure generating groove on a surface thereof, wherein a photoresist film is formed on a bearing surface of a ceramic body, and then through a mask conforming to the shape of the dynamic pressure generating groove. Exposure and development are performed to remove the photoresist film only in the portion that will become the dynamic pressure generating groove, and to spray hard fine particles having an average particle size of 2 to 20 μm over the entire bearing surface to remove the photoresist film. A dynamic pressure generating groove is formed.
[0021]
Here, the reason why the average particle size of the hard fine particles is 2 to 20 μm is that if the average particle size is less than 2 μm, the processing efficiency is poor, and it is difficult to control the uniform dispersion. This is because the bottom surface cannot have a surface roughness of 1 μm or less.
[0022]
Further, the depth of the dynamic pressure generating groove is preferably in the range of 2 to 30 μm. If the depth is less than 2 μm, it becomes difficult to control the dimensional accuracy, and good surface smoothness cannot be obtained. Conversely, if the depth is more than 30 μm, the groove becomes tapered and the bottom corner of the groove becomes a large R surface, and sufficient dynamic performance is obtained. This is because it is difficult to obtain a pressure effect. Preferably, the thickness is in the range of 2 to 20 μm.
[0023]
The ceramic dynamic pressure bearing of the present invention is a thrust or radial bearing comprising a shaft and a bearing, wherein the shaft and / or the bearing is formed of ceramics and has a dynamic pressure generating groove on its bearing surface. Say things.
[0024]
【Example】
Hereinafter, a dynamic thrust bearing used in a dynamic bearing device of a spindle motor for a VTR will be described as an embodiment of the present invention.
[0025]
As shown in FIG. 5, the dynamic pressure bearing device includes a shaft 21, a dynamic pressure thrust bearing 22, and a sleeve 23, and the sleeve 23 rotates around the shaft 21 as a fixed shaft. A herringbone-shaped dynamic pressure generating groove 24a is formed on the outer periphery of the shaft 21 to form a dynamic pressure radial bearing portion 24, and the dynamic pressure thrust bearing 22 has a spiral dynamic pressure generating groove 22a. At the time of rotation, a fluid film is formed by these dynamic pressure generating grooves 22a and 24a, and smooth rotation can be performed.
[0026]
However, at the time of start / stop, at the time of low-speed rotation, the tip of the shaft 21 slides on the dynamic pressure thrust bearing 22, and the entire load of the rotating body is applied as a load to the tip of the shaft 21 and the dynamic pressure thrust bearing 22. Become.
[0027]
As shown in FIG. 1, the dynamic pressure thrust bearing 22 has a spiral dynamic pressure generating groove 2 in the center of the surface of the ceramic body 1, and the convex portion 3 and the outer peripheral portion 4 in the dynamic pressure generating groove 2 Are in the same plane. If the end face of the shaft 21 is supported and rotated by the dynamic pressure thrust bearing 22, the shaft 21 can be floated by the dynamic pressure action of the dynamic pressure generating groove 2.
[0028]
The ceramic body 1 is made of ceramics having a Young's modulus of 300 GPa or more and an average crystal grain size of 0.5 μm or more, and the surface roughness (Ra) of the bottom 2 a of the dynamic pressure generating groove 2 is 1 μm or less.
[0029]
The dynamic pressure thrust bearing 22 of the present invention uses a highly rigid material having a Young's modulus of 300 GPa or more as ceramics, so that it does not easily deform even when a load is applied, and can maintain an excellent dynamic pressure generating effect. Further, since ceramics having a large average crystal grain size of 0.5 μm or more are used, the edge 2b of the dynamic pressure generating groove 2 is not sharpened, and the mating material is hardly worn. Further, by setting the surface roughness (Ra) of the bottom portion 2a of the dynamic pressure generating groove 2 to 1 μm or less, the holding force of the fluid film can be increased, and the abrasion due to sliding with the counterpart material can be prevented.
[0030]
In order to reduce the surface roughness (Ra) of the bottom portion 2a of the dynamic pressure generating groove 2 to 1 μm or less, the hard fine particles at the time of sandblasting may have a predetermined particle size in a manufacturing method described later. Alternatively, press molding can be performed using a mold having the shape of the dynamic pressure generating groove 2. In this case, press molding and firing may be performed with the surface roughness (Ra) of the mold set to 1 μm or less. .
[0031]
When the above-described dynamic bearing device is used for a spindle motor of a VTR, the speed is as high as about 3000 rpm, and when the spindle motor of an LBP (laser beam printer) is used, it is as high as about 20,000 rpm. At this time, the shaft 21 and the dynamic pressure thrust bearing 22 violently slide under a load at the time of start / stop. However, as described above, the average crystal particle diameter is 0.5 μm or more, and the dynamic pressure generating groove is formed. By setting the surface roughness (Ra) of the bottom 2a of the second to 2 μm or less, the fluid film of the lubricant can be uniformly interposed, and the amount of cutting wear can be reduced and the lubricant can be favorably used for a long period of time.
[0032]
Although the dynamic thrust bearing 22 has been described in the above embodiment, the ceramic dynamic pressure bearing of the present invention is not limited to this. For example, the end face of the shaft 21 is formed of ceramics to form a dynamic pressure generating groove, or the shaft 21 or the sleeve 23 of the radial bearing portion 24 is formed of ceramics and provided with a dynamic pressure generating groove, and the dynamic pressure generating groove of the present invention is formed. It can be a dynamic pressure bearing.
[0033]
Next, a method for manufacturing the dynamic thrust bearing of the present invention shown in FIG. 1 will be described.
[0034]
As shown in FIG. 2 (a), first, after the bearing surface 1a of the ceramic body 1 is finished to a desired surface state, preferably a surface roughness (Ra) of 0.3 μm or less, a film-like photoresist film 11 is formed on the entire surface. Are laminated so that air bubbles are not involved. The thickness t of the photoresist film 11 is 30 μm or more so as to withstand the impact of shot blast described later. However, if the thickness is more than necessary, there is a problem that the edge of the dynamic pressure generating groove 2 formed at the time of processing cannot be formed with high precision. Therefore, the thickness t is preferably 200 μm or less. This thickness t can be appropriately changed according to the depth of the groove to be processed.
[0035]
Thereafter, a glass mask 12 as shown in FIG. 3 is manufactured. In the glass mask 12, a portion corresponding to the dynamic pressure generating groove 2 in FIG. 1 is an opaque portion 12a, and the other portion is a transparent portion 12b. The shape of the glass mask 12 may be accurately transferred based on a drawing manufactured using CAD or the like.
[0036]
As shown in FIG. 2B, the glass mask 12 manufactured here is placed in close contact with the surface of the photoresist film 11, and is exposed to ultraviolet light from above. At this time, the exposed portions of the photoresist film 11 are cured. That is, the portion of the photoresist film 11 corresponding to the transparent portion 12b of the glass mask 12 is exposed and cured, while the portion corresponding to the opaque portion 12a is not exposed and is not cured.
[0037]
Thereafter, by removing the glass mask 12 and spraying a developing solution while rotating the ceramic body 1, as shown in FIG. 2C, only the uncured ultraviolet light unexposed portions 11a of the photoresist film 11 are removed. Will be done. That is, the photoresist film 11 on the surface of the ceramic base 1 is in a state where the portion of the shape of the opaque portion 12a of the glass mask 12 (the shape of the dynamic pressure generation groove 2) is removed and only the other portion is adhered. The desired shape of the dynamic pressure generating groove 2 is accurately masked on the surface of the ceramic body 1.
[0038]
As described above, according to the present invention, since the masking is formed by exposing and developing the photoresist film 11, a desired shape can be easily and accurately formed even if the masking is separated. Although a negative photoresist is used in the above embodiment, it is needless to say that a desired shape of the dynamic pressure generating groove 2 can be similarly formed by using a positive photoresist.
[0039]
Further, the ceramic body 1 and the photoresist film 11 are baked at 150 to 200 ° C. to improve the strength of the photoresist film 11.
[0040]
Finally, as shown in FIG. 2D, after the ceramic body 1 obtained as described above is set in the apparatus, hard fine particles 14 are injected from the injection nozzle 13 onto the bearing surface 1a of the ceramic body 1 and shot. Perform blasting. In this step, the portion of the bearing surface 1a of the ceramic body 1 from which the photoresist film 11 has been removed is shaved, and the dynamic pressure generating groove 2 is formed.
[0041]
Here, in order to form the dynamic pressure generating groove 2 with high precision, a method of controlling the hard fine particles 14 is important. Specifically, the hard fine particles 14 are always supplied while being measured at a constant weight so that the injection amount per time is constant. Further, the hard fine particles 14 are uniformly dispersed in air that has been dried and introduced from a high-pressure air source via a drier or silica gel, and is jetted. In particular, in the case of fine particles, it is very easy to aggregate, so it is important to use dry air.
[0042]
Further, as the hard fine particles 14, GC abrasive No. 2500 was used, but in addition, silicon carbide or alumina generally used for shot blasting of ceramics having an average particle size of 2 to 20 μm is used. May be used. Here, the reason why the average particle diameter of the hard fine particles 14 is 2 to 20 μm is that if it is less than 2 μm, processing efficiency is poor and it is difficult to control uniform dispersion. This is because the surface roughness (Ra) of the bottom 2a of the second material 2 cannot be less than 1 μm. Then, the injected hard fine particles 14 are collected and reused. At this time, the hard fine particles 14 that have become small due to crushing or abrasion are removed, and the average particle diameter is always maintained in the range of 2 to 20 μm. It is important to keep.
[0043]
As described above, the hard fine particles 14 are constantly metered and supplied to keep the injection amount per time constant, and the hard fine particles 14 which have become smaller at the time of reuse are removed to maintain the average particle diameter constant. The pressure generating groove 2 can be processed with high precision, and the flatness of the bottom surface 2a can be processed to 3 μm or less.
[0044]
In this shot blasting process, as shown in FIG. 4, a plurality of ceramic bodies 1 are placed on the base plate 15 and the base plate 15 and the nozzle 13 are relatively moved while being repeatedly scanned. If the dynamic pressure generating grooves 2 are gradually formed, the uniform and high precision dynamic pressure generating grooves 2 can be formed.
[0045]
The material of the ceramic body 1 forming the dynamic pressure thrust bearing 22 includes alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), calcium titanate (CaTiO ₃ ), barium titanate (BaTiO ₃ ), and silicon nitride. (Si ₃ N ₄ ), silicon carbide (SiC), altic (Al ₂ O ₃ —TiC), cermet (TiC—TiN-based), or the like is used. Cermet is preferred.
[0046]
Further, in the above embodiment, the dynamic pressure generating groove is formed in the dynamic pressure thrust bearing 22. However, the shaft 21 may be formed of ceramics, and the dynamic pressure generating groove may be formed on the end face thereof. The manufacturing method of the present invention can also be applied. Further, the manufacturing method of the present invention can be applied not only to the thrust bearing but also to the case where a dynamic pressure generating groove is formed in the shaft 21 and / or the sleeve 23 in the radial direction.
[0047]
Experimental example 1
Here, a dynamic pressure thrust bearing of the present invention shown in FIG. 1 was prototyped, and a test using a ball-on-disk type friction and wear test was performed to examine wear resistance and slidability.
[0048]
As an example of the present invention, a hydrodynamic thrust bearing 22 made of alumina-based ceramics, silicon nitride-based ceramics, and TiC-TiN-based cermet was prepared. On the other hand, as a comparative example, one made of SKH material, one made of zirconia ceramics, and one made of alumina ceramics was used. A material having a roughened surface roughness at the bottom of the dynamic pressure generating groove was prepared.
[0049]
Each sample was subjected to a sliding test under a wet lubrication condition using a ball of high carbon chromium bearing steel SUJ2 as a mating material at a load of 0.5 kg and a relative sliding speed of 0.17 m / s. The results of measuring the amount of wear are as shown in Table 1.
[0050]
As is evident from Table 1, the amount of wear on the mating material was no. While the comparative examples of Nos. 4 to 6 are large, the comparative examples Nos. It is understood that all of the samples Nos. 1 to 3 have extremely small amounts of wear of the mating material, and among them, the cermet is very excellent. No. 1 and No. Comparing No. 6 with No. 6 in which the surface roughness (Ra) of the bottom of the dynamic pressure generating groove was larger than 1 μm despite the same alumina-based ceramic. In No. 6, the amount of wear of the mating material was large. Further, the zirconia ceramics of No. 5 had too small a crystal grain size of 0.5 μm or less, so that the edge of the dynamic pressure generating groove was sharpened, causing cutting wear on the mating material.
[0051]
Therefore, by using ceramics having a Young's modulus of 300 GPa or more and an average crystal grain size of 0.5 μm or more and setting the surface roughness (Ra) of the bottom of the dynamic pressure generating groove to 1 μm or less, it is possible to make it difficult to wear the mating material. .
[0052]
[Table 1]

[0053]
Experimental example 2
Next, the thrust bearing shown in FIG. 1 was manufactured by the above manufacturing method. The ceramic body 1 was formed by Altic, and performance evaluation was performed when the depth of the dynamic pressure generating groove 2 was changed.
[0054]
The results are as shown in Table 2. In Table 1, No. In No. 1, the processing time could not be controlled because the groove depth was too shallow, and an unprocessed portion remained on the surface of the ceramic body 1 and a predetermined dynamic pressure effect could not be obtained. No. In No. 7, since the groove depth is deep, the cross section of the dynamic pressure generating groove 2 has a tapered shape in which the width decreases toward the back, and a large R surface is generated at a corner, and a predetermined dynamic pressure effect is obtained even in performance evaluation. I couldn't do that.
[0055]
On the other hand, No. 3 having a groove depth of 2 to 30 μm. With respect to Nos. 2 to 6, there was no problem in terms of accuracy and performance. Particularly, those having a groove depth of 2 to 20 μm (Nos. 2 to 5) showed excellent dynamic pressure effects.
[0056]
[Table 2]

[0057]
【The invention's effect】
As described above, according to the present invention, a ceramic dynamic pressure bearing having a dynamic pressure generating groove on its surface is formed of ceramics having a Young's modulus of 300 GPa or more and an average crystal grain size of 0.5 μm or more, and generates a dynamic pressure. By reducing the surface roughness (Ra) of the groove bottom to 1 µm or less, the cutting wear of the mating material due to the edge of the dynamic pressure generating groove is reduced, and the lubricant is uniformly interposed on the bearing surface to reduce the amount of wear. , High reliability and long life can be achieved.
[0058]
Further, according to the present invention, when forming a dynamic pressure generating groove of a ceramic dynamic pressure bearing, masking is performed by using exposure and development of a photoresist film to accurately and without any shape restriction. Masking can be easily performed. In addition, by jetting the controlled hard fine particles on the surface, processing on the order of submicron is realized, and mass production processing of the ceramic dynamic pressure bearing having a desired concave groove can be performed with high precision.
[Brief description of the drawings]
FIG. 1 shows a dynamic pressure thrust bearing which is an example of a ceramic dynamic pressure bearing of the present invention, wherein (a) is a plan view and (b) is a sectional view taken along line XX in (a).
FIG. 2 is a diagram illustrating a method for manufacturing a ceramic dynamic pressure bearing of the present invention.
FIG. 3 is a plan view showing a glass mask used in the method for manufacturing a ceramic dynamic pressure bearing of the present invention.
FIG. 4 is a diagram illustrating a method for manufacturing a ceramic dynamic pressure bearing according to the present invention.
FIG. 5 is a sectional view showing a general dynamic pressure bearing device.
[Explanation of symbols]
1: Ceramic body 2: Dynamic pressure generating groove 2a: Bottom part 3: Convex part 4: Outer peripheral part 22: Dynamic pressure thrust bearing

Claims (4)

A ceramic dynamic pressure bearing having a dynamic pressure generating groove on its surface is formed of ceramic having a Young's modulus of 300 GPa or more and an average crystal grain size of 0.5 μm or more, and has a surface roughness (Ra) at the bottom of the dynamic pressure generating groove. A ceramic dynamic pressure bearing having a thickness of 1 μm or less. 2. The ceramic dynamic pressure bearing according to claim 1, wherein the ceramic is an Altic or a cermet. In the method of manufacturing a ceramic dynamic pressure bearing having a dynamic pressure generating groove on the surface, after forming a photoresist film on the bearing surface of the ceramic body, exposure is performed through a mask conforming to the shape of the dynamic pressure generating groove, and development is performed. Removing the photoresist film at the portion that will become the dynamic pressure generating groove, and spraying hard fine particles having an average particle size of 2 to 20 μm on the surface to form the dynamic pressure generating groove at the portion without the photoresist film A method for manufacturing a ceramic dynamic pressure bearing, comprising manufacturing the ceramic dynamic pressure bearing according to claim 1 . 4. The method according to claim 3, wherein a depth of the dynamic pressure generating groove is 2 to 30 [mu] m.

Images