JP2003139137A - Dynamic pressure bearing unit and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic pressure bearing unit to properly manage a gap between radial bearings and a gap between thrust bearings and obtain further high rotation precision. SOLUTION: When an end face 2b2 (2b1) of a flange part 2b of a shaft member 2 being the constitution element of the dynamic pressure bearing unit 1 is ground, the rotation center part on one end side of the shaft member 2 is supported in a point-contact state, a surface is machined with a tool 13 (14) brought into press contact with the end face 2b2 (2b1) of the flange part 2b from the other end side. The rotation center part is supported in a point contact state by a protrusion-form curve part 12a in a spherical shape or a taper part in a conical shape and in the shape of a pyramid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure type bearing unit and a method for manufacturing the same, and more particularly to information equipment such as HD.
Magnetic disk devices such as D and FDD, CD-ROM, DV
The present invention relates to a dynamic pressure type bearing unit used for supporting a spindle such as an optical disk device such as a D-ROM, a spindle motor such as a magneto-optical disk device such as an MD or MO, or a polygon scanner motor of a laser beam printer (LBP), and a manufacturing method thereof. .

[0002]

2. Description of the Related Art A spindle motor for driving a disk in various types of information equipment is required to have high rotation accuracy, high speed, low cost, and low noise. A bearing for supporting the spindle of this type of motor is required. Is one of the important components that determine these required performances. Therefore, under the present circumstances, as this type of bearing, use of a dynamic pressure type bearing having characteristics excellent in the required performance has been studied or put into practical use.

Further, in recent years, in the spindle motor for the above information equipment, there is a strong demand for high rotation accuracy in order to increase the information recording density and increase the rotation speed, and in order to meet this request, the above spindle motor is required. Higher rotational accuracy is also required for the dynamic pressure type bearing incorporated in the.

[0004]

By the way, in order to improve the rotation accuracy of the dynamic pressure type bearing, it is important to manage the clearance in the radial bearing gap or the thrust bearing gap in which the dynamic pressure is generated. In order to optimize this clearance management, it is necessary to accurately process a component of the dynamic pressure type bearing related to each bearing clearance, for example, a shaft member that forms each bearing clearance with the bearing member. Therefore, the method of manufacturing or manufacturing the shaft member is one of the factors that determine the rotation accuracy of the dynamic pressure type bearing.

More specifically, as shown in FIG. 4, a shaft member 2'is formed by integrally forming a flange portion 2b 'on the base end of a shaft portion 2a', and a bearing member (not shown) on the outer periphery thereof. ) Is placed. Then, a radial bearing gap is formed between the outer peripheral surface 2a1 'of the shaft portion 2a' and the bearing member, and the thrust bearing is provided between the front end surface 2b1 'and the base end surface 2b2' of the flange portion 2b 'and the bearing member, respectively. A gap is formed.

In manufacturing the shaft member 2 ', the following steps have been conventionally performed. That is, as shown in FIG. 5, a pair of rotating rolls 10 'that rotate in the direction of arrow a and a peripheral surface supporting member (shoe) 11' are pressed against the outer peripheral surface 2a1 'of the shaft portion 2a' to bring the shaft member 2 into contact. As shown in FIG. 6, the tip end surface (a flat surface) of the end face support member 12 'that is axially formed on the tip end surface 2a2' of the shaft portion 2a 'in a state where the rotation is imparted to
Grinding (including polishing; the same applies hereinafter) is performed by pressing the tool 13 'against the base end surface 2b2' of the flange portion 2b 'while making the surface contact with each other.

As for the tip end surface 2b1 'of the flange portion 2b', the same end surface support member 12 'as shown in FIG.
Grinding is performed by pressing the tool 14 'onto the tip end surface 2b1' of the flange portion 2b 'while making the tip end surface of the flange portion 2b' into surface contact with the base end surface 2b2 '.

In this case, the flange portion which is the above-mentioned ground surface
The processing accuracy of the front end surface 2b1 'or the base end surface 2b2' of 2b 'is the perpendicularity of the front end surface of the end surface support member 12' with respect to the pressing contact surface of the peripheral surface support member 11 ', and the front end surface of the end surface support member 12'. Is greatly affected by the perpendicularity of the outer peripheral surface 2a1 'of the shaft portion 2a' to the tip end surface 2a2 'of the shaft portion 2a' or the base end surface 2b2 'of the flange portion 2b', which is the contact surface.

Therefore, as described above, the end face support member 1
Since the tip surface of 2'has been in surface contact with the tip surface 2a2 'of the rotating shaft portion 2a' or the base end surface 2b2 'of the flange portion 2b', these end surfaces 2a2 ', 2b2' and the shaft portion Even if there is a slight deviation in the perpendicularity of the outer peripheral surface 2a1 'of 2a', the shaft member 2 may cause rattling (runout) in the axial direction during processing.

Therefore, the flange portion after grinding
The machining finish accuracy of both end surfaces 2b1 'and 2b2' of 2b 'is unavoidable to be maintained, and the dynamic pressure type bearing obtained by incorporating this shaft member 2'will be an obstacle to secure further high rotation accuracy. Is concerned.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a dynamic pressure type bearing unit in which gap management of radial bearing gaps and thrust bearing gaps is optimized to obtain higher rotational accuracy. Subject.

[0012]

DISCLOSURE OF THE INVENTION The present invention, which has been made in order to achieve the above-mentioned technical objects, provides a shaft member having a flange portion on the base end side of the shaft portion, and a bearing member arranged on the outer periphery of the shaft member. A bearing surface having a dynamic pressure groove and a bearing gap facing the bearing surface, and the dynamic pressure generated in the bearing gap during relative rotation between the shaft member and the bearing member causes the shaft member to move in the radial direction and In a dynamic pressure type bearing unit including a radial bearing portion and a thrust bearing portion that are supported in a non-contact manner in the thrust direction, the squareness of both end surfaces of the flange portion with respect to the outer peripheral surface of the shaft portion of the shaft member is 0.00
The flatness of both end surfaces of the flange portion is 2 mm or less and 0.001 mm or less, respectively. Here, the "bearing member" includes a structure in which a bearing member having a radial bearing surface and a thrust bearing surface is fixed to the housing, and a structure in which the radial bearing surface and the thrust bearing surface are directly formed on the housing.

According to this structure, since the deviation of the squareness and the flatness of the main part of the shaft member is set to be equal to or less than the required extremely small value, the radial bearing gap and the thrust bearing gap are properly managed, This avoids problems such as contact between the bearing surfaces during relative rotation of the shaft member and bearing member, or unstable rotation due to insufficient dynamic pressure in the bearing gap. Fluctuations are suppressed and high rotation accuracy can be obtained.

Further, according to the present invention made to achieve the above technical problem, a shaft member having a flange portion on the base end side of the shaft portion, a bearing member arranged on the outer periphery of the shaft member, and a dynamic pressure A bearing surface having a groove and a bearing gap facing the bearing surface are provided respectively, and the shaft member is not moved in the radial direction and the thrust direction due to the dynamic pressure generated in the bearing gap when the shaft member and the bearing member are relatively rotated. In a method of manufacturing a dynamic pressure bearing unit including a radial bearing portion and a thrust bearing portion that support in contact with each other, the shaft member is axially supported at one end side while rotating about the axis, and the flange portion is provided from the other end side. It includes a step of pressing a tool against the end surface of the shaft to perform surface processing, and in this step, the center of rotation on the one end side of the shaft member is supported by point contact. Here, the “face processing” means, for example, cutting processing.

According to this structure, when the end face of the flange portion of the shaft member is machined, the rotation center portion on one end side of the shaft member is axially supported by point contact, and the flange portion is pressed from the other end side. Since the tool comes into pressure contact with the end surface of the shaft part, even if the squareness of the outer peripheral surface of the shaft part with respect to the end surface of the shaft member on the point contact support side is incorrect, the end surface is not supported in surface contact and the center of rotation is not supported. Since the point contact is supported by point contact, the deviation of the squareness does not adversely affect the rotation of the shaft member, and there is no possibility that the shaft member rattles (runs) in the axial direction. Therefore, the squareness of the end surface of the flange portion with respect to the outer peripheral surface of the shaft portion after processing and the flatness of the end surface of the flange portion can be finished with high accuracy.

According to such a manufacturing method, the perpendicularity of the end surface of the flange portion with respect to the outer peripheral surface of the shaft portion is 0.002 mm.
The flatness of the end face of the flange is 0.0
It has been proved by an experiment conducted by the present inventors that the distance is 01 mm or less (details will be described later). Therefore, the dynamic pressure type bearing unit manufactured according to the present invention can enjoy the same advantages as the dynamic pressure type bearing unit according to the above invention.

As one mode of this manufacturing method, the center of rotation of the tip end surface of the shaft portion is supported by point contact, and the tool is pressed into contact with the base end surface of the flange portion.

As another aspect of this manufacturing method,
It is possible to support the center of rotation of the base end surface of the flange portion by point contact, and press the tool into contact with the tip end surface of the flange portion.

Here, the above-mentioned "proximal end" means the end on the flange portion side when the shaft portion side and the flange portion side of the shaft member are assumed, and the "tip end" is the shaft portion side. Means the end of.

As one mode of the point contact support, it is possible to support the rotation center by point contact with a convex curved surface. In this case, the tip end point of the convex curved surface portion comes into contact with the rotation center portion. Then, the shape of the convex curved surface portion can be a spherical shape.

Another aspect of the point contact support is to support the center of rotation in a point contact by a tapered portion. In this case, the tip point of the tapered portion comes into contact with the rotation center portion. Then, the shape of the tapered portion can be a conical shape or a pyramidal shape.

In the manufacturing method having the above structure, it is preferable that the outer peripheral surface of the shaft portion is brought into contact with the rotating roll and the peripheral surface supporting member to rotate the shaft member around the axis. With this configuration, the shaft member can be preferably rotated with a simple structure by the mutual operation of the rotating roll and the peripheral surface supporting member, and the end surface processing of the flange portion can be efficiently performed.

In the dynamic pressure type bearing unit manufactured by using the above method, the clearance management in the radial bearing clearance and the thrust bearing clearance is optimized as described above, and the higher rotational accuracy is obtained. It will be extremely advantageous.

[0024]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the following description based on FIG. 1, the “tip” means the upper end, and the “base end” means the lower end.

As shown in FIG. 1, a dynamic pressure type bearing unit (hereinafter, simply referred to as a bearing unit) 1 includes a shaft member 2 and
A so-called bag-shaped housing 3 having a cylindrical shape with a bottom, and a bearing member 4
And a seal member 5 such as a seal washer that seals the tip side of the bearing member 4 (the opening side of the housing 3).

The shaft member 2 has a shaft portion 2a and a flange portion 2b integrally formed on the base end side of the shaft portion 2a.
2a is arranged on the inner circumference of the bearing member 4, and the flange portion 2b is arranged between the base end surface 41 of the bearing member 4 and the bottom portion 3a of the housing 3 to be housed in the unit. The bottom 3a of the housing 3 closes the base end side opening of the housing 3 and may be formed integrally with the housing 3 or may be formed as a separate bottom lid member.

The bearing member 4 is formed of a soft metal, a sintered metal impregnated with oil, or the like. A radial bearing surface 4a1 having a plurality of dynamic pressure grooves 4a is formed on the inner circumference of the bearing member 4 by transfer, rolling or the like by press working, whereby when the shaft member 2 and the bearing member 4 rotate relative to each other ( In the present embodiment, when the shaft member 2 rotates), the radial bearing surface 4a1 and the shaft portion 2a
The dynamic pressure of the fluid (for example, lubricating oil) filled in the radial bearing gap Rs1 between the outer peripheral surface 2a1 and the outer peripheral surface 2a1 is generated, and this dynamic pressure action forms the radial bearing Ra that supports the shaft 2a in the radial direction in a non-contact manner. To be done. In addition, in a partial area of the outer peripheral surface 2a1 of the shaft portion 2a, a recessed portion having a slightly smaller diameter than other areas.
2ax is provided, and the dynamic pressure groove 4a is formed in each of two regions corresponding to the front end side and the base end side of the recessed portion 2ax.

A thrust bearing gap Ss, which is a gap in the axial direction, is provided on both axial sides of the flange portion 2b of the shaft member 2.
1, Ss2 are provided. One thrust bearing gap Ss1 is
Tip surface 2b1 of flange 2b and bearing member 4 facing it
Is formed between the base end surface 41 of the
Ss2 is the base end surface 2b2 of the flange portion 2b and the bottom portion of the housing 3.
It is formed between the inner bottom surface 3a2 of 3a.

On the end faces facing the thrust bearing gaps Ss1 and Ss2, for example, the base end face 41 of the bearing member 4 and the inner bottom face 3a2 of the housing 3, dynamic pressure generating grooves (not shown) are formed.
The thrust bearing surfaces 4b1 and 3b2 having the above are formed, whereby the fluid dynamic pressure is generated in the thrust bearing gaps Ss1 and Ss2 during the above rotation, and the thrust bearing portion Sa that supports the flange portion 2b from both sides in the thrust direction in a non-contact manner. Is configured. In addition, in the central region of the base end surface 2b2 of the flange portion 2b, a recessed portion 2bx slightly recessed with respect to other regions is formed.

The dynamic pressure groove shapes of the radial bearing surface 4a1 and the thrust bearing surfaces 4b1 and 3b2 can be arbitrarily selected, and any known herringbone type, spiral type, step type, multi-arc type or the like can be selected. Alternatively, these can be used in appropriate combination. The bearing member 4
A herringbone type dynamic pressure groove 4a is formed on the radial bearing surface 4a1 as an example.

Regarding the accuracy of the main part of the shaft member 2,
Both end surfaces 2b1 of the flange portion 2b with respect to the outer peripheral surface 2a1 of the shaft portion 2a,
The squareness of 2b2 is 0.002 mm or less, and the flatness of both end surfaces 2b1 and 2b2 of the flange portion 2b is 0.001.
It is set to mm or less. Therefore, when the bearing unit 1 is used in, for example, an HDD which is a kind of information equipment, the radial bearing gap Rs1 and the thrust bearing gaps Ss1 and Ss2 are properly managed, and the rotation accuracy thereof is enhanced.

Here, the term "squareness" means the amount of deviation of the predetermined surface from a geometric plane that is geometrically perpendicular to the reference plane in the combination of the reference plane and the predetermined plane that should be orthogonal. Say it. This is because, for example, while rotating the shaft member 2 around the axis, the contactor is brought into contact with each of the front end face 2b1 and the base end face 2b2 of the flange portion 2b, and each end face 2
It is represented by measuring the maximum value of the swing width at b1 and 2b2. Further, the "flatness" means the difference in height between the maximum convex portion and the minimum concave portion on the measurement surface. In any case, when the dynamic pressure groove exists on the target plane, the virtual plane connecting the spine (mountain) portions between the dynamic pressure grooves is used as a reference.

Next, in the manufacturing method of the bearing unit 1, particularly in each step of the manufacturing method, both end surfaces of the flange portion 2b of the shaft member 2 (before the dynamic pressure groove and the recessed portion 2bx are formed) are formed. A process of grinding 2b1 and 2b2 will be described.

In this step, the means for rotating the shaft member 2 around the shaft center imparts the rotation to the shaft member 2 by sandwiching the outer peripheral surface 2a1 of the shaft portion 2a, as in the structure already shown in FIG. And a peripheral surface supporting member (shoe) 11 that presses and contacts the outer peripheral surface 2a1 of the shaft portion 2a at a predetermined pressure.

The flange portion of the shaft member 2
When the base end surface 2b2 of 2b is ground, as shown in FIG. 2, the end surface support member 12 that axially supports the tip end surface 2a2 of the shaft portion 2a by point contact, and the base end surface 2b2 of the flange portion 2b. And a whetstone 13 having a substantially flat surface at its tip that comes into contact with a predetermined processing pressure. At the tip of the end face support member 12, a spherical convex curved surface portion 12a is provided so as to project, and the tip of the convex curved surface portion 12a is in point contact with the center of rotation of the tip surface 2a2 of the shaft portion 2a. It is configured.

According to this structure, the pair of rotating rolls 10 rotate in the direction of arrow a, so that the peripheral surface supporting member is rotated.
The shaft member 2 rotates in the direction of arrow b in the state where 11 is in contact with the outer peripheral surface 2a1 of the shaft portion 2a. Then, during this rotation, the shaft portion 2a
In a state in which the tip end surface 2a2 of the end face support member 12 is point-contact supported by the convex curved surface portion 12a, the tip end of the grindstone 13 is pressed into contact with the base end face 2b2 of the flange portion 2b, and the base end face 2b2 is ground. Done.

Regarding the shaft member 2 to be subjected to this grinding process, even if the squareness of the tip surface 2a2 with respect to the outer peripheral surface 2a1 of the shaft portion 2a is bad, the tip surface 2a2 of the shaft portion 2a has its center of rotation. Is supported by the convex curved surface portion 12a in a point contact manner, so that the posture of the shaft member 2 maintained by the rotating roll 10 and the peripheral surface supporting member 11 is maintained. As a result, as compared with the conventional case where the tip end surface 2a2 of the shaft portion 2a is supported by surface contact with a flat surface, rattling or shake generated in the shaft member 2 is suppressed as much as possible, and the flange after grinding is processed. The flatness of the base end surface 2b2 of the portion 2b and the squareness of the base end surface 2b2 of the flange portion 2b with respect to the outer peripheral surface 2a1 of the shaft portion 2a are finished with high accuracy.

On the other hand, the flange portion 2b of the shaft member 2
When the tip end surface 2b1 of the above is ground, the base end surface 2b2 of the flange portion 2b is axially supported by point contact, in addition to the rotating roll 10 and the peripheral surface support member 11, as shown in FIG. The same end face support member 12 as described above and a whetstone 14 having a substantially flat surface at the tip contacting the tip surface 2b1 of the flange portion 2b with a predetermined processing pressure are provided.

According to this structure, the flange portion is rotated when the shaft member 2 is rotating around the axis in the same manner as described above.
In a state where the base end surface 2b2 of 2b is point-contact supported by the convex curved surface portion 12a of the end surface support member 12, the tip end of the grindstone 14 is pressed into contact with the tip end surface 2b1 of the flange portion 2b, and the tip end surface 2b1 is ground. Is done.

Therefore, also in this case, even if the squareness of the base end surface 2b2 of the flange portion 2b with respect to the outer peripheral surface 2a1 of the shaft portion 2a is deviated, the rotation center portion of the base end surface 2b2 is convex. Since it is supported by point contact by the curved surface portion 12a,
The rattling or shake generated in the shaft member 2 is suppressed as much as possible, and the flatness of the tip end surface 2b1 of the flange portion 2b after grinding and the flange portion 2b of the shaft portion 2a with respect to the outer peripheral surface 2a1.
The squareness of the tip surface 2b1 of the is accurately finished. Such an effect is remarkably obtained when the front end face 2b1 of the flange portion 2b is ground before the front end face 2b2 thereof is ground. Therefore, when the base end surface 2b2 of the flange portion 2b is ground first by the above-described method, the squareness of the base end surface 2b2 with respect to the outer peripheral surface 2a1 of the shaft portion 2a is finished with high accuracy, It is also possible to adopt a conventional method (method shown in FIG. 7) when grinding the tip surface 2b1 of the flange portion 2b thereafter.

[0041]

EXAMPLE In order to confirm the effect of the present invention, the following experiment was conducted. First, stainless steel (SUS420J
Shaft member (2) consisting of 2), shaft part (2a) and flange part (2b)
It was manufactured by integrally forming and. This shaft member (2) has a total length of 15 mm, an outer diameter of the shaft portion (2a) of 4.5 mm, and a flange portion (2
The outer diameter of b) is 7 mm, and the width (thickness) of the flange portion (2b) is 1.
It was set to 2 mm. Then, as an embodiment of the present invention, the base end surface (2b2) and the tip end surface (2b1) of the flange portion (2b) of the shaft member (2) are ground by the method shown in FIGS. 2 and 3, As a comparative example, the base end surface (2b2) and the tip end surface (2b1) of the flange portion (2b) of the shaft member (2) were ground by the method shown in FIGS. 6 and 7.
Base face (2b2) of flange (2b) after this grinding process
And the respective flatness of the tip surface (2b1), the squareness of the base end surface (2b2) with respect to the outer peripheral surface (2a1) of the shaft portion (2a), the tip surface (2b1) with respect to the outer peripheral surface (2a1) of the shaft portion (2a). Squareness was measured for each of the example and the comparative example. The measurement results are shown in Table 1 below.

[0042]

[Table 1]

According to Table 1 above, in the embodiment of the present invention,
The flatness of both end surfaces (2b1) and (2b2) of the flange portion (2b) is 0.001 mm or less (more specifically 0.0005 mm or less)
And the flange part (2a1) to the outer peripheral surface (2a1) of the shaft part (2a).
The squareness of both end faces (2b1) and (2b2) of b) is 0.001m.
m and 0.002 mm or less (more specifically 0.001
5 mm or less). On the other hand, in the comparative example, the flatness of both end surfaces (2b1) and (2b2) of the flange portion (2b) is 0.
More than 001 mm, the squareness of both end surfaces (2b1) and (2b2) of the flange portion (2b) with respect to the outer peripheral surface (2a1) of the shaft portion (2a) exceeds 0.002 mm.

Next, by incorporating the shaft member (2) according to the example and the shaft member (2) according to the comparative example into the state shown in FIG. 1, two types of dynamic pressure type bearing units (1) Was produced. These dynamic pressure type bearing units (1) are
The inner diameter of (4) is 4.5 mm, its outer diameter is 7 mm, its width (axial dimension) is 8 mm, and the radial bearing clearance (Rs1)
Is 0.002-0.003 mm, thrust bearing clearance (Ss
1) and (Ss2) were set to 0.01 to 0.02 mm. And
These two types of dynamic pressure type bearing units (1) were incorporated into a test motor, and the rotational synchronous vibration (RRO) and the rotational asynchronous vibration (NRRO) in the radial direction were evaluated. This evaluation test is performed at 5000r 5 minutes after the test motor is started.
It was performed using a non-contact displacement gauge under the condition of pm. The test results are shown in Table 2 below.

[0045]

[Table 2]

According to Table 2 above, the dynamic pressure type bearing unit (1) incorporating the shaft member (2) according to the embodiment of the present invention is
It can be said that the NRRO is significantly lower than that of the comparative example and the bearing performance is excellent.

Further, regarding the above two types of test motors,
Under the condition that the shaft member (2) is in a vertical posture, the bearing load is 75 g, and the oil kinematic viscosity is 20 mm ² / S, the shaft member 2 that is floating when the rotation speed is stopped from the operating state of 3000 rpm The number of rotations at which the inner bottom surface (3a2) began to contact (contact start rotation number) was measured. This measurement result is shown in Table 3 below.
Shown in.

[0048]

[Table 3]

According to Table 3 above, the test motor using the shaft member (2) according to the embodiment of the present invention has a contact start rotational speed significantly lower than the test motor using the comparative example. . In this case, if the contact start rotation speed becomes higher, the wear of the thrust bearing surfaces (4b1) and (3b2) will progress accordingly and the durability will deteriorate, so in consideration of this, the above embodiment was used. It can be said that the test motor has excellent durability.

[0050]

As described above, according to the dynamic pressure type bearing unit of the present invention, the squareness of both end surfaces of the flange portion with respect to the outer peripheral surface of the shaft portion of the shaft member which is a main component of the unit is 0. Since the flatness of both end faces of the flange portion is 002 mm or less and 0.001 mm or less, the radial bearing gap and the thrust bearing gap are properly managed, and excellent bearing performance can be obtained. Fluctuations are suppressed and high rotation accuracy can be secured.

Further, according to the method of manufacturing the dynamic pressure type bearing unit of the present invention, the center of rotation on one end side of the shaft member is supported by point contact, and the tool is pressed from the other end side to the end surface of the flange portion. Since the surface processing is performed by contacting, the shaft member is appropriately surface-processed without rattling (runout) in the axial direction, and the squareness of the end surface of the flange portion with respect to the outer peripheral surface of the shaft portion after processing, In addition, the flatness of the end surface of the flange portion is finished with high accuracy as high as that of the dynamic pressure type bearing unit according to the above-mentioned invention. Therefore, also in this case, a dynamic pressure type bearing unit having excellent bearing performance and high rotation accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a dynamic pressure type bearing unit according to an embodiment of the present invention.

FIG. 2 is a schematic plan view showing an implementation state of the method for manufacturing the dynamic pressure bearing unit according to the embodiment of the present invention.

FIG. 3 is a schematic plan view showing another embodiment of the method for manufacturing the dynamic pressure bearing unit according to the embodiment of the present invention.

FIG. 4 is a schematic front view showing a shaft member that is a main constituent element of a dynamic pressure type bearing unit according to an embodiment of the present invention and a conventional example.

FIG. 5 is a schematic side view showing an implementation state of a method for manufacturing a dynamic pressure bearing unit according to an embodiment of the present invention and a conventional example.

FIG. 6 is a schematic plan view showing an implementation state of a method of manufacturing a dynamic pressure type bearing unit according to a conventional example.

FIG. 7 is a schematic plan view showing another embodiment of the method for manufacturing the dynamic pressure type bearing unit according to the conventional example.

[Explanation of symbols]

1 Dynamic pressure bearing unit 2 shaft members 2a Shaft 2a1 Shaft outer peripheral surface 2b Flange part 2b1 Flange end surface 2b2 Flange base surface 3 Housing (bearing member) 4 Bearing member 4a Dynamic pressure groove 4a1 radial bearing surface Rs1 radial bearing clearance Ra radial bearing section Ss1 Thrust bearing clearance Ss2 Thrust bearing clearance Sa thrust bearing 10 revolving roll 11 Peripheral support member 12 End support member 12a Convex curved surface 13 Tool (grinding stone) 14 Tool (grinding stone)

Claims (10)

[Claims] 1. A shaft member having a flange portion on the base end side of the shaft portion, a bearing member arranged on the outer periphery of the shaft member, a bearing surface having a dynamic pressure groove, and a bearing gap facing the bearing surface. A dynamic bearing including a radial bearing portion and a thrust bearing portion that are provided in each of them and that support the shaft member in the radial direction and the thrust direction in a non-contact manner by the dynamic pressure generated in the bearing gap when the shaft member and the bearing member rotate relative to each other. In the pressure type bearing unit, the squareness of both end surfaces of the flange portion with respect to the outer peripheral surface of the shaft portion of the shaft member is 0.002 mm or less, and the flatness of both end surfaces of the flange portion is 0.001 m.
A dynamic pressure type bearing unit characterized by being m or less. 2. A shaft member having a flange portion on the base end side of the shaft portion, a bearing member arranged on the outer periphery of the shaft member, a bearing surface having a dynamic pressure groove, and a bearing gap facing the bearing surface. A dynamic bearing including a radial bearing portion and a thrust bearing portion that are provided in each of them and that support the shaft member in the radial direction and the thrust direction in a non-contact manner by the dynamic pressure generated in the bearing gap when the shaft member and the bearing member rotate relative to each other. In the method for manufacturing a pressure bearing unit, a step of supporting the shaft member in the axial direction at one end side while rotating the shaft member around the shaft center and pressing the tool from the other end side to the end surface of the flange portion to perform surface processing A method for manufacturing a dynamic pressure type bearing unit, comprising supporting the center of rotation on one end side of the shaft member by point contact in the step. 3. The method for manufacturing a dynamic pressure type bearing unit according to claim 1, wherein the center of rotation of the tip end surface of the shaft portion is supported by point contact, and the tool is pressed into contact with the base end surface of the flange portion. 4. The method of manufacturing a dynamic pressure type bearing unit according to claim 1, wherein the center of rotation of the base end surface of the flange portion is supported by point contact, and the tool is pressed into contact with the tip end surface of the flange portion. 5. The method of manufacturing a dynamic pressure type bearing unit according to claim 2, wherein the center of rotation is supported by a convex curved surface portion in point contact. 6. The method for manufacturing a dynamic pressure type bearing unit according to claim 5, wherein the convex curved surface portion has a spherical shape. 7. The method for manufacturing a dynamic pressure type bearing unit according to claim 2, wherein the center of rotation is supported by a tapered portion in point contact. 8. The method of manufacturing a dynamic pressure type bearing unit according to claim 7, wherein the tapered portion has a conical shape or a pyramidal shape. 9. The dynamic pressure type bearing unit according to claim 2, wherein the rotating roll and the peripheral surface supporting member are brought into contact with the outer peripheral surface of the shaft portion to rotate the shaft member around the shaft center. Production method. 10. A dynamic pressure type bearing unit manufactured by using the method according to claim 2.