JPH10306821A - Method for stabilizing sliding of dynamic pressure bearing and dynamic pressure bearing - Google Patents

Abstract

(57) [Problem] To provide an inexpensive dynamic pressure bearing capable of maintaining stable sliding characteristics by performing a surface finish equivalent to a lap finish by a running-in operation and saving the time for a final finish. SOLUTION: A polygon motor is assembled by a dynamic pressure air bearing 20 configured using a fixed shaft 9 and a rotating shaft 10 which are not subjected to lapping. Both the fixed shaft and the rotating shaft have a base material made of an aluminum alloy, and a plasma sprayed film made of a material mainly composed of alumina is formed on a rotating sliding surface. The above motor (ie dynamic pressure air bearing)
When the running-in operation was performed in a CHF ₃ gas atmosphere at room temperature and normal pressure, stable operation could be performed without any trouble such as shaft lock, and the fixed shaft and the rotating shaft after the operation were The surface accuracy of the sliding surface was equal to or better than the lap finish. The motor after the above-mentioned running-in operation has the same quality as a motor that has been subjected to a conventional final finishing process, and can be used as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stabilizing the sliding of a dynamic pressure bearing such as a dynamic pressure air bearing having a sliding surface of ultraprecision machining, which is used for a small motor rotating at a high speed (a running operation method). More particularly, the present invention relates to a method for stabilizing the sliding of a dynamic pressure bearing suitable for the configuration of a motor such as a high-speed rotating polygon motor used for a digital copying machine, a laser facsimile, a laser printer, or the like.

[0002]

2. Description of the Related Art Digital copiers, laser facsimile machines,
2. Description of the Related Art Electrophotographic recording apparatuses using a laser writing system such as a laser printer are rapidly spreading due to excellent features such as high printing quality, high-speed printing, low noise, and low price. A polygon motor (polygon scanner), which is a component of the laser writing system of these recording devices, is required to have a rotation speed according to the printing speed and the pixel density of the recording device.

In recent years, with the increase in print speed and the increase in pixel density, polygon motors require 15,000 to 25,000.
Since high-speed rotation of 000 rpm or more is required, if a conventional ball bearing type is used as the bearing, the required quality cannot be satisfied in terms of bearing life, bearing noise, and the like. Therefore, as a polygon motor for high-speed rotation, a motor using a grooved dynamic pressure air bearing has been put into practical use instead of a conventional ball bearing.

Here, the structure of a conventional dynamic air bearing will be described. FIG. 2 is a longitudinal sectional view showing the structure of the dynamic pressure air bearing provided in the polygon motor. This dynamic pressure air bearing includes a hollow rotary shaft 51 that is an outer cylinder member and a fixed shaft 52 that is an inner cylinder member (bearing member). A groove 52a for generating dynamic pressure is formed on the outer peripheral surface of the fixed shaft 52, and the outer peripheral surface of the fixed shaft 52 is a bearing surface (excluding the groove 52a). The rotating body 61 is constituted by the rotating shaft 51, the rotor magnet 53, the polygon mirror 54, and the like. The rotating shaft 51 and the fixed shaft 52 are made of an aluminum alloy, and the grooves 52a are subjected to a surface treatment such as electroless nickel plating or alumite, which is not shown, to also prevent rust.

When the polygon motor is started and stopped, in the above-mentioned dynamic air bearing, the bearing sliding surface (rotating sliding surface) between the rotating shaft 51 and the bearing surface of the fixed shaft 52 is in contact with each other. When the rotating shaft 51 starts rotating by the activation, a dynamic pressure is generated in a gap between the rotating shaft 51 and the fixed shaft 52, that is, in the groove 52a.
Are supported in a non-contact manner with the fixed shaft 52.

[0006]

Conventionally, in manufacturing a hydrodynamic air bearing having the above structure, the roughness of the sliding surface between the rotary shaft 51 and the fixed shaft 52 is reduced to about 5 μm by Rmax by grinding. Rmax 0.5 μm by lapping
Finished to a degree. The reason for this is that if such a surface finish is not applied, the minute projections on the sliding surface will be destroyed in the process of fitting in the bearing, and the particulate bearing material will inevitably fall between the rotating shaft 51 and the fixed shaft 52. This is because a gap (shaft clearance) is generated, which may damage other parts of the bearing, resulting in large-scale wear. However, there is a problem that it is difficult to provide a hydrodynamic air bearing of desired quality at a low cost because the surface finishing involves a considerable cost.

Particularly, in the dynamic pressure air bearing, since the above-mentioned shaft clearance is small as compared with other dynamic pressure bearings, it is important to increase the surface accuracy of the rotating shaft alone and the fixed shaft alone (that is, the rotating shaft and the bearing member). Of course,
Actually, the assembling accuracy when these are assembled so as to be slidable with each other is also important. Therefore, it is indispensable to match the compatibility between the rotating shaft and the bearing member by performing a running-in operation (a running-in operation). In this case, if the finishing accuracy of the rotating shaft and bearing members is insufficient, abnormal wear will occur during running-in operation and the shaft torque will increase.In the worst case, a fatal obstacle such as shaft lock will occur. Or

Japanese Patent Publication No. 7-37810 discloses an invention in which a sliding surface of a dynamic pressure gas bearing is defined in order to reduce damage during running-in operation. An object of the present invention is to improve the life and performance of a dynamic pressure bearing in which a rotating shaft and a bearing member slide with each other at the time of starting and stopping, and to reduce loss torque at the time of starting. That is, in the above-mentioned hydrodynamic gas bearing, a predetermined lubricant is applied to the bearing surface whose sliding surface is formed of dense ceramics and the surface roughness Ra of the sliding surface is reduced to 0.3 μm or less. It is characterized in that a thin film having a thickness of 20 to 100 ° having a uniform protective and lubricating action is provided on the surface. However, the above-mentioned invention has no idea to reduce the burden of finishing the bearing sliding surface by running-in operation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object the purpose of performing a surface finish equivalent to a lap finish by a running-in operation (a running-in operation), and reducing the time required for the final finishing, thereby achieving a stable operation. An object of the present invention is to provide an inexpensive dynamic pressure bearing capable of maintaining sliding characteristics.

In order to achieve the above object, the present invention has established a method for stabilizing the sliding of a dynamic pressure bearing by reviewing the running-in operation as a final finishing step of the dynamic pressure bearing. Ultimately, it is desirable that the running-in operation also serves as a final finishing step of the rotating shaft and the bearing member. According to this, the most time-consuming and costly steps in the manufacturing process of the dynamic pressure bearing can be omitted. The dynamic pressure bearing treated by the sliding stabilization method of the present invention is particularly effective for producing a polygon motor for a copying machine or the like, which is provided with a dynamic pressure bearing that requires a sliding surface for high-speed ultra-precision machining. is there.

[0011]

According to a first aspect of the present invention, there is provided a method for stabilizing the sliding of a dynamic pressure bearing, wherein a rotating shaft and a rotating sliding surface of a bearing member are fixed to a predetermined position in a dynamic pressure bearing used for a polygon motor or the like. It is made of a material, and the rotating shaft is rotated and slid with respect to the bearing member by running-in operation under a predetermined fluid environment to perform the same surface finish as lap finish. It is characterized by achieving stabilization, particularly stabilization of initial running-in operation.

According to a second aspect of the present invention, in the method for stabilizing sliding of the dynamic pressure bearing, the shear force is applied to each other by rotating and rotating the rotating shaft with respect to the bearing member. Changes in the shape and chemical composition of the rotary sliding part between the rotary shaft and the bearing member due to a chemical reaction between the fluid forming the fluid environment and the rotary sliding surface of the rotary shaft and the bearing member, which occurs only in the It is characterized by making it.

According to a third aspect of the present invention, in the method for stabilizing the sliding of the dynamic pressure bearing, the fluid comprises a fluorine atom having a very low chemical activity under ordinary temperature and pressure conditions. A gas or a liquid containing

According to a fourth aspect of the present invention, in the method for stabilizing sliding of the dynamic pressure bearing, the gas is CHF ₃ as the gas.
(Fluoroform), CF ₄ (carbon tetrafluoride) or SF ₆ (sulfur hexafluoride), or C ₅ F as the liquid
It is characterized by using a perfluoroalkyl carbon such as ₁₂ (perfluoropentane).

According to a fifth aspect of the present invention, there is provided a method of stabilizing the sliding of a dynamic pressure bearing, wherein a predetermined motor such as a polygon motor is used by using a dynamic pressure bearing comprising a rotating shaft having a rotating sliding surface formed of a predetermined material and a bearing member. After assembling to the final configuration, the running-in operation of the motor is performed by the method according to claim 3 or 4.
In addition, the operation is performed under the same conditions as the actual use conditions of the motor.

According to a sixth aspect of the present invention, there is provided a method for stabilizing sliding of a dynamic pressure bearing according to the third, fourth or fifth aspect, wherein at least one of the rotating shaft and the rotating sliding surface of the bearing member is desirable. It is characterized in that both are formed of oxide ceramics.

According to a seventh aspect of the present invention, there is provided a method for stabilizing the sliding of a dynamic pressure bearing according to the third or fourth aspect, wherein at least one of the rotating shaft and the rotating sliding surface of the bearing member is desirable. It is characterized in that both are formed of stainless steel.

According to a eighth aspect of the present invention, there is provided a method for stabilizing the sliding of a dynamic pressure bearing according to any one of the first to seventh aspects, wherein the rotary sliding surface of the rotary shaft and the rotary sliding of the bearing member are provided. A predetermined motor such as a polygon motor is assembled up to the final configuration using a dynamic pressure bearing in which at least one of the moving surfaces has a surface roughness Rmax of 1 μm or more.

The dynamic pressure bearing according to the ninth aspect has the following features.
8 is manufactured by the sliding stabilization method described in any one of the above items.

Hereinafter, the configuration of the present invention will be specifically described.
The purpose of the running-in operation of the dynamic pressure bearing is to remove an abnormally shaped portion, that is, a convex portion remaining on the sliding surface even in the final finishing. As a result, the contact surface pressure between the rotating shaft and the bearing member can be made uniform, and abnormal wear of the sliding surface can be reduced. Therefore, the slack operation is no different from the final finishing of the rotating shaft and the bearing member in that the unevenness is smoothed.

Even so, even if the bearing is started by simply assembling the rotating shaft and the bearing member with low finishing accuracy, wear powder accumulates in the shaft clearance and the shaft torque increases, or the shaft lock is lost. It is easily assumed that it is impossible to perform the final finishing because it occurs. In the above case, the fact that the wear powder grows in the shaft clearance indicates that the wear powder wears the sliding surface constituent material or that the wear powder combines with other wear powder in the shaft clearance. I have. Therefore, the present inventor has focused on the latter and proceeded with the study.

In many cases, the connection between the abrasion powders is caused by the atmosphere surrounding the abrasion powders. In a verification experiment, when a glass disk is rubbed with alumina spheres, a chemical bond between alumina and glass occurs in the atmosphere due to the action of oxygen, and alumina also wears. At this time, the abrasion powder grows greatly and deposits so as to stick to the glass. On the other hand, in an atmosphere of an inert gas such as nitrogen, such a phenomenon does not occur, and alumina wears glass unilaterally, so that abrasion powder of glass generated by destruction does not grow.

From the above experiments, it was confirmed that the atmosphere of wear greatly affects the quality and quantity of wear powder. In other words, it can be said that the interaction between the sliding 2 solid and the atmosphere has an important effect on the form of wear. Therefore, it has been found that by appropriately controlling this interaction, there is a possibility that the stability of the running-in operation is greatly improved.

However, it must be noted that the above interaction is limited to the contact point between the sliding two solids. Corrosion reactions of metals in acidic electrolytes proceed on all the metal surfaces that come into contact with the electrolyte, and thus, on the entire contact surface between the surrounding fluid (for example, atmospheric gas) and the sliding solid. If the reaction has progressed, it is not possible to achieve the purpose of the running-in operation of the bearing for removing only the minute projections. Ideally, the running-in operation is performed after the bearings are completely assembled as a unit. This is because there is a problem that the components may be damaged at the time of final assembly even if the familiarity is performed at the component stage. Taking a polygon motor as an example, when the bearing is assembled to the motor, a control system is also attached to the motor, so that at least a process of immersing the motor in the electrolyte cannot be performed.

The inventor of the present invention has proposed a gas or a liquid containing fluorine atoms as constituent atoms, which has extremely low chemical activity under ordinary temperature and pressure conditions, as a fluid for forming an environment in which the bearings can be operated smoothly. We considered using it.

SF ₆ (sulfur hexafluoride), which is a kind of such a gas, is used as an inert gas in insulating materials and the like. SF ₆ generates radicals containing fluorine atoms that have the property of corroding many materials in plasma. According to recent studies, it has been pointed out that in the field of solid contact, something like microplasma is generated, and a very active field is locally generated. Therefore,
If energy enough to dissociate the fluorine-containing inert material represented by SF ₆ mentioned above is generated at the contact point between the sliding two solids, only the contact point is corroded by fluorine-containing atom radicals, Thus, it is considered that there is a possibility that the running-in operation of the bearing can be performed.

The present inventor studied the effect of running-in operation of the bearing by using CHF ₃ (fluoroform) gas, which is a kind of fluorine-containing inert material, as an atmospheric gas.
As a result, only at the point of contact between the rotating shaft and the bearing member,
The solid material undergoes a chemical change to generate fluorine compounds of these solid materials, and this fluorine compound has a lower hardness than the solid material forming the rotating shaft and the sliding surface of the bearing member before running-in operation. It was confirmed that.

Therefore, unless the fluorine compound of the solid material becomes wear powder and detaches from the sliding surface and does not grow due to mutual adhesion, CHF ₃ gas is effective as a familiar operation atmosphere. Available to achieve the objects of the present invention. By taking the above-mentioned characteristics into consideration in designing the material for forming the sliding surface, it becomes possible to positively use the running-in operation as the final finishing process.

Next, an embodiment of the present invention will be described.

【Example】

Embodiment 1 FIG. 1 is a longitudinal sectional view of a polygon motor (polygon scanner) manufactured in this embodiment. In this polygon motor, a dynamic pressure air bearing 20 composed of a fixed shaft 9 and a hollow rotary shaft 10 is used in the radial direction. Further, the fixed shaft 9 and the rotating shaft 10 are made of an aluminum alloy having a small specific gravity in order to reduce the weight of the motor and to rotate at high speed, and each of the rotating sliding surfaces is made of ceramics mainly composed of alumina (oxide ceramics). Formed. Therefore, the fixed shaft 9 and the rotating shaft 1
On the surface of No. 0, a film made of the ceramics was formed by plasma spraying. In FIG. 1, 7 is a rotating body, 21 is a magnetic bearing, and 22 is a motor unit.

In order to form the sliding surfaces of the fixed shaft 9 and the rotating shaft 10 with ceramics containing aluminum as a main component, there is also a method in which the whole of the fixed shaft 9 and the rotating shaft 10 is made of a sintered body of the ceramic. It is possible. As a method of forming a ceramic film, CVD, sputtering, wet (plating, anodic oxidation) and the like can be adopted. However, the plasma spraying method has a higher film forming rate than other methods, and has an aluminum alloy as a base material. There is an advantage that the adhesion to the film is high.

The housing 1 has a flange-shaped reference surface 1a for attachment to an optical housing (not shown).
A printed circuit board 3 constituting the motor unit 22 is disposed inside the housing 1 and is fixed to the housing 1 with screws or an adhesive. A winding coil 4 and a Hall element 5 are mounted on the back side of the printed circuit board 3 and are pattern-wired to a connector 6. The motor system is a coreless brushless motor in which a flat rotor magnet 8 attached to a rotating body 7 and a winding coil 4 face each other in the axial direction. A circuit board (drive circuit) 17 is integrally provided below the housing 1 and connected to the printed circuit board 3 of the motor with a harness 18. The energization is switched to rotate the rotating body 7 to perform constant speed control.

At the center of the housing 1, a fixed shaft 9 constituting a dynamic air bearing is firmly fixed by press-fitting or shrink fitting. On the outer peripheral surface of the fixed shaft 9, a herringbone groove 9a for forming a dynamic pressure air bearing is provided.
Is paired. When the rotating body 7 starts rotating, the pressure in the gap between the rotating shaft 10 and the fixed shaft 9 increases, forming a dynamic pressure bearing and supporting the rotating body 7 in a radial direction without contact.
A magnet 11a is fixed to the upper end of the hydrodynamic air bearing, and magnets 11b and 11 attached to the rotating body 7 and the cover 12 are provided.
An upper and lower repulsion type magnetic bearing 21 for supporting the rotating body 7 in the axial direction together with the micro holes 13 for c and the vibration damping is formed.

In the rotating body 7, a polygon mirror 14 is mounted on the upper surface of a flange portion 10a formed in the middle of the rotating shaft 10, and a screw is screwed to the rotating shaft 10 with a mirror retainer 15 interposed therebetween. The mirror 14 is locked and fixed. A rotor yoke 16 is bonded and fixed to the lower side of the rotating body 7, and a rotor magnet 8 for a motor is further bonded and fixed. Since the rotor magnet 8 is made of plastic, it has a higher linear expansion coefficient and lower mechanical strength than metal. Therefore, by forming the rotor yoke 16 in a cup shape and holding the outer diameter portion of the rotor magnet 8, expansion of the rotor magnet 8 in the radial direction due to centrifugal force due to high-speed rotation or thermal expansion due to heat generation is suppressed, and 7 is prevented from being lost or the rotor magnet 8 is not broken. Further, by using a ferromagnetic material for the rotor yoke 16, the magnetic path is closed to prevent magnetic flux leakage, thereby increasing the motor efficiency. As a material of the rotor yoke 16, for example, a steel or stainless steel plate material is used.

At the upper part of the motor (upper part of the scanner), a cover 12 whose inside is hollowed out so as to surround the rotating body 7 rotatably fitted to the fixed shaft 9 is fixed to the housing 1 with screws. In the cover 12, a glass window is fixed to an opening for inputting and outputting laser light from a semiconductor laser (not shown) with a double-sided tape or an adhesive, and is sealed.

On the other hand, in the rotating body 7, the balance is corrected by two correcting surfaces 19a and 19b at upper and lower portions of the rotating body so that unbalanced (unbalanced) vibration is at a very small level. In order to easily and efficiently perform the balance correction work, it is better that the initial imbalance is small. Therefore, each component (8, 10, 14, 15, 16, 16, 1) of the rotating body 7 is preferable.
1b) is manufactured such that the amount of eccentricity with respect to the rotation axis is as small as possible within the processing accuracy range in consideration of economy. Rotor yoke 16 which is one of the components of the rotating body
Are also positioned in the rotary shaft fitting cylindrical portion with a relatively small fitting gap, and are adhesively fixed.

Experimental Example 1 The polygon motor described in Example 1 was used. That is, four types × 3 polygon motors having the same basic configuration as shown in FIG. 1 but different in the degree of finishing of the sliding surfaces of the dynamic pressure air bearings (the fixed shaft 9 and the rotating shaft 10). The above was prepared, and the familiar operation was performed for each. In the conventional dynamic pressure air bearing (fixed shaft and rotating shaft that constitutes),
The finishing accuracy of the sliding surface needs to be about 0.5 μm in Rmax. This is the surface accuracy that can be achieved by performing lapping or the like after grinding. However, in this example, ground and fixed shaft / rotation shaft grinding products before lapping were also used as samples. The used polygon motors (four types) are as follows.

Polygon motor A: Product equivalent to lap for both rotating shaft and fixed shaft (bearing member) Polygon motor B: Product equivalent to lap for rotating shaft, ground product for fixed shaft Polygon motor C: Grind product for rotary shaft, wrap for fixed shaft Equivalent product Polygon motor D: Grinding product for both rotating shaft and fixed shaft During familiar running, the entire polygon motor was housed in a case with a simple structure to control the atmosphere. As the atmosphere gas, three kinds of air, nitrogen gas and CHF ₃ gas (all at room temperature and normal pressure) were used. The results are shown in Table 1 below.

[0038]

[Table 1] Evaluation Criteria: ：: Good adaptation possible ○: Almost good adaptability possible ×: Good adaptability was not possible

In the motor A, the adaptation was stable with any of the atmosphere gases, but in the motors B, C and D, the adaptation stability was greatly different depending on the type of the atmosphere gas. In the following, we explain this,
The effectiveness of the present invention will be clarified.

In the atmosphere, none of the motors B, C, and D could perform good adaptation, and most of them caused serious sliding failure such as shaft lock. At this time, when the motor was disassembled and the degree of damage to the sliding surface was observed, peeling of the sprayed film occurred in all cases.

On the other hand, in the running-in operation of the motors B and C in the nitrogen gas atmosphere, no fatal shaft lock occurred. However, a rise in torque was confirmed during running-in operation, and when disassembled and inspected, a large amount of abrasion powder generated not only from the grinding product side but also from a part of the spray coating on the lap equivalent product side was generated inside the shaft clearance. It was confirmed that it had accumulated on The above-mentioned abrasion powder includes particles having a size equal to or larger than the clearance, which is presumed to be the cause of the increase in the rotational torque. In some cases, the rotation of the motor D is stopped during the running-in operation, and it is considered that the generation amount of the wear powder is related to the finishing accuracy. However, unlike the familiar operation in the atmosphere, there was nothing that led to the peeling of the sprayed film. It is presumed that when the oxygen gas is contained in the atmosphere gas, the adhesive force between the abrasion powders is increased and the sprayed film is peeled off.

When CHF ₃ gas is used as the ambient gas, a stable running-in operation is required for all of the motors A, B, C and D (even when the fixed shaft and the rotating shaft are ground products). Was completed. As a result of this running-in operation, abrasion powder was observed in the shaft clearance, but the sliding surfaces of the fixed shaft and the rotating shaft were equivalent to those of the equivalent lap finish.
Or, the surface accuracy was higher than this.

The wear powder in the shaft clearance due to the running-in operation in the CHF ₃ gas atmosphere was significantly finer than that in the running-out operation in the nitrogen gas atmosphere.
When elemental analysis was performed on the abrasion powder, fluorine was detected. This indicates that when the rotating shaft and the fixed shaft come into contact with each other, they are chemically reacting with the CHF ₃ gas. Fluorine was also detected from the sliding surfaces of the rotating shaft and the fixed shaft. Furthermore, it was confirmed that the hardness of the outermost surface of the sliding surface was lower than that of alumina.

From the above, it has become clear that the following effects can be obtained by performing the familiar operation in the CHF ₃ gas atmosphere. (1) Even if a fixed shaft and a rotating shaft that do not perform finishing equivalent to the lap are used, a running-in operation can be performed without causing a fatal sliding failure such as a shaft lock.
A polygon motor having excellent sliding characteristics can be obtained. (2) The size of the abrasion powder inevitably generated during the running-in operation can be reduced, and the growth of the abrasion powder having a size larger than the shaft clearance can be prevented. (3) A surface layer having a lower hardness than the sliding surface is formed on the sliding surface of the fixed shaft or the rotating shaft, whereby a solid lubricating action on the sliding surface occurs.

The chemistry described above by CHF ₃ gas, because only occurs when the atmosphere of dynamic bearing was maintained at CHF ₃ gas will be appreciated that the polygon motor after running-normal in the environment When placed, the chemical action does not proceed further. Also CH
Since the F ₃ gas selectively acts only on the part that is rotating and sliding, no phenomenon such as corrosion of other members of the motor occurs.

As an atmosphere gas, instead of CHF ₃ , a fluorine atom which does not show chemical activity under a normal environment, such as CF ₄ (carbon tetrafluoride) or SF ₆ (sulfur hexafluoride), is used as a constituent atom. When the same running-in operation was performed using a gas containing the same gas, excellent results equivalent to those of the above-described example were obtained. Further, when a polygon motor was immersed in perfluoroalkyl carbon represented by C ₅ F ₁₂ (perfluoropentane) (which is a liquid under a normal environment), the same running-in operation as in the above embodiment was performed. Equally good results were obtained.

Example 2 A polygon motor was assembled in the same manner as in Example 1 except that the sliding surfaces of the fixed shaft and the rotating shaft were formed of stainless steel, and conformed in a CHF ₃ gas atmosphere in the same manner as in Example 1. I drove. As a result, good results equivalent to those in Example 1 were obtained.

[0048]

As apparent from the above description, according to the present invention, the following remarkable effects can be obtained. (1) Effect of the method for stabilizing sliding of a dynamic pressure bearing according to claim 1: A rotating shaft and a rotating sliding surface of a bearing member are formed of a predetermined material, and a running-in operation is performed under a predetermined fluid environment. Thus, it is possible to save time and effort for final finishing of the rotating shaft and the bearing member, and to provide a low-cost dynamic pressure bearing capable of maintaining stable sliding characteristics. Therefore, according to the present invention, even when a rotating shaft and a bearing member that have not been subjected to a finish equivalent to a lap finish are used, a critical failure such as a shaft lock does not occur with a small number of processes (no trouble occurs during a running-in operation). In addition, a small high-speed rotation motor such as a highly reliable polygon motor can be manufactured at low cost.

(2) Effect of the method for stabilizing sliding of a dynamic pressure bearing according to the second aspect: Only when a rotating shaft is rotationally slid with respect to a bearing member to mutually exert a shearing force, The fluid according to claim 1, wherein a chemical reaction is caused between the fluid forming the fluid environment and the rotating sliding surface of the rotating shaft and the bearing member to change a shape and a chemical composition of the rotating sliding portion. Familiar driving that produces an effect can be performed.

(3) Effect of the method for stabilizing sliding of a dynamic pressure bearing according to the third and fourth aspects: a gas or liquid containing fluorine atoms as constituent atoms, which has extremely low chemical activity under ordinary conditions as the fluid. By using, the location where the chemical reaction occurs can be limited to the rotary sliding portion, so that it is possible to prevent problems such as corrosion from occurring in portions other than the sliding portion.

(4) Effect of the method for stabilizing sliding of the dynamic pressure bearing according to the fifth aspect: After a predetermined motor such as a polygon motor is finally assembled using the dynamic pressure bearing according to the first aspect, A dynamic pressure bearing having excellent sliding characteristics in a smaller number of steps as compared with the prior art by performing the running-in operation of the motor by the method according to claim 3 or 4 and under the same conditions as actual use conditions of the motor. Can be manufactured, and a more inexpensive dynamic pressure bearing (therefore, a high-speed rotation motor provided with the same) can be provided.

(5) Effects of the method for stabilizing sliding of a dynamic pressure bearing according to claims 6 and 7: By forming the rotating sliding surfaces of the rotating shaft and the bearing member from oxide ceramics or stainless steel, The hardness of the abrasion powder generated by the running-in operation of the dynamic pressure bearing can be made lower than that of the material for forming the rotary sliding surface, and the abrasion powder can be prevented from adhering and growing at the shaft clearance.

(6) Advantages of the method for stabilizing sliding of a dynamic pressure bearing according to claim 8, wherein the surface roughness Rmax of at least one of the surface of the rotating shaft and the surface of the bearing member is set to 1 μm or more, By assembling the pressure bearing to the final configuration,
The manufacturing process of dynamic pressure bearings can be greatly simplified,
It can be provided at low cost.

(7) Advantages of the dynamic pressure bearing according to the ninth aspect: By manufacturing a motor using a dynamic pressure bearing which has been subjected to a predetermined sliding stabilization process, a polygon motor having excellent sliding characteristics. Can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a polygon motor according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a conventional dynamic air bearing.

[Explanation of symbols]

 7 Rotating Body 9 Fixed Shaft (Bearing Member) 9a Herringbone Groove 10 Rotating Shaft 14 Polygon Mirror 17 Circuit Board (Drive Circuit) 20 Dynamic Pressure Air Bearing 21 Magnetic Bearing 22 Motor Part

Claims (9)

[Claims] 1. A dynamic pressure bearing used for a polygon motor or the like, wherein a rotary shaft and a rotary sliding surface of a bearing member are formed of a predetermined material, and the rotary shaft is attached to the bearing member by running-in operation under a predetermined fluid environment. On the other hand, a dynamic pressure bearing characterized by achieving the same surface finish as lap finish by rotating and sliding, eliminating the need for final finishing and stabilizing rotating and sliding, especially the initial running-in operation. Sliding stabilization method. 2. The method according to claim 1, wherein the fluid forming the fluid environment is generated only when the rotating shaft is rotationally slid with respect to the bearing member so as to exert a shearing force on each other. Wherein the shape and chemical composition of the rotary sliding portion between the rotary shaft and the bearing member are changed by a chemical reaction between the rotary shaft and the rotary sliding surface of the bearing member. Method. 3. The method according to claim 2, wherein a gas or a liquid containing fluorine atoms as constituent atoms and having extremely low chemical activity under normal temperature and pressure conditions is used as the fluid. A sliding stabilization method for dynamic pressure bearings. 4. The method according to claim 3, wherein the gas is CHF ₃ (fluoroform), CF ₄ (carbon tetrafluoride) or SF ₆ (sulfur hexafluoride), or the liquid is C ₅ F _12. A method for stabilizing sliding of a dynamic pressure bearing, comprising using a perfluoroalkyl carbon such as (perfluoropentane). 5. After assembling a predetermined motor such as a polygon motor to a final configuration using a hydrodynamic bearing including a rotating shaft and a bearing member having a rotating sliding surface formed of a predetermined material, a running-in operation of the motor is performed. A method for stabilizing sliding of a dynamic pressure bearing, wherein the method is performed by the method according to claim 3 and under conditions equivalent to actual conditions of use of the motor. 6. The method according to claim 3, wherein at least one of the rotating shaft and the rotating sliding surface of the bearing member, preferably both, are formed of oxide ceramics. A method for stabilizing bearing sliding. 7. The dynamic pressure bearing according to claim 3, wherein at least one of the rotating shaft and the rotating sliding surface of the bearing member is preferably made of stainless steel. Sliding stabilization method. 8. The method according to claim 1, wherein a surface roughness Rmax of at least one of the rotating sliding surface of the rotating shaft and the rotating sliding surface of the bearing member is 1 μm.
A method for stabilizing sliding of a dynamic pressure bearing, comprising assembling a predetermined motor such as a polygon motor to a final configuration using a dynamic pressure bearing set to m or more. 9. A dynamic pressure bearing produced by the method for stabilizing sliding according to claim 1. Description: