JP2001012455A - Dynamic pressure bearing with identification groove - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing of excellent identifying performance permitting easy identification of groove items by visually checking dynamic pressure generating grooves. SOLUTION: A deep groove 3 bored deeper than a dynamic pressure generating groove 2 is formed at the bottom face of the dynamic pressure generating groove 2, partitioning its angular parts with sharp edges. The deep groove 3 is provided in plural intermittent or continuous streak form, and a large number of characteristic identification patterns formed by the deep grooves 3 can be provided by a combination formed by varying the repetition pitch and streak layout pattern, and these identification patterns are allotted every item of the grooves 2 and used for visual identification. In the case of forming the dynamic pressure generating grooves 2 by plural time scanning of laser beam irradiation, the beam moving pitch is made the overlap pitch of beam diameters to permit the deep grooves 3 to be formed simultaneously with the formation of the grooves 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure bearing for a spindle motor used for a small storage device such as a hard disk, a bar code reader, and the like. The present invention relates to a dynamic bearing having identification means for identifying a groove for generating a dynamic pressure.

[0002]

2. Description of the Related Art In a dynamic pressure bearing used for a small storage device such as a hard disk or a spindle motor provided for a bar code reader, rigidity, levitation force, etc.
Alternatively, matching with a motor is an important characteristic. Of these, the levitation force depends on the number, width, size, inclination, depth, etc. of the generally spiral grooves carved in the bearing to generate dynamic pressure.
It is known that the floating performance of the bearing changes. Therefore, in order for the assembled spindle motor to exhibit a predetermined levitation force, it is essential that a member in which a predetermined groove is processed is incorporated in its bearing portion, which is a problem in processing an individual groove. This means that it is important not only to control the accuracy but also to strictly control the lot of the bearing member after the groove processing so that a bearing member having necessary specifications can be incorporated without error.

Various technologies such as bar codes, identification tags, and marking application are already known and used for product category management. But with these commonly known methods,
Even though individual component units can be identified, it is often difficult to use them for identification of the specific component after the component has been incorporated therein. There is a similar problem in the member for generating dynamic pressure of the bearing which is symmetrical in the present invention.

FIG. 4 shows a thrust plate for generating a dynamic pressure according to the prior art. As described above, this thrust plate 21 is generally formed in a spiral shape having a constant inclination with respect to the center of the bearing as described above. A plurality of grooves are provided, and by the relative rotation between this surface and another bearing member opposed thereto, the action of the spiral groove allows a gas such as air or a fluid such as oil to conduct between the two members, thereby Utilizing the generated dynamic pressure, the members are kept in a non-contact state.
At this time, for example, as the depth of the spiral groove 22 for generating the dynamic pressure, the depth d of about 0.2 μm to 5 μm shown in FIG. However, it is extremely difficult or impossible to visually identify and divide each of the groove depths provided with a delicate depth change in this range at the time of assembling or after assembling. Not only the groove depth but also the number, width, shape, inclination, and the like of the grooves, it is often difficult to instantaneously identify them visually.

There is a technique such as lot management using a pallet. However, even in the case of using this method, depending on the dimensional accuracy of other bearing members, for example, a thrust plate having different depths and other specifications is selectively used. In some cases, there is a problem that components having different specifications are likely to be mixed.

In order to distinguish the thrust plates 21 having different groove specifications as individual components, a large identification mark or the like can be attached to the back surface thereof. Not available.

FIG. 5 shows that the thrust plate 21 as described above is
For example, this shows an example of a state after being incorporated as a bearing portion of a spindle motor. In the figure, reference numeral 21 denotes a thrust plate provided with a spiral groove 22 for generating the dynamic pressure. The thrust plate 21 is incorporated in a housing 23. A sleeve 24 is fixed to the housing 23, and a fixed radial bearing 26 is fixed to the sleeve 24.
The rotating side radial bearing 28 is attached to the shaft 27 fitted to the sleeve 24 so as to face the fixed side radial bearing 26 with a predetermined gap. A rotation-side thrust bearing 29 is attached to the lower end surface of the shaft 27 in the drawing, and is opposed to the thrust plate 21 with a predetermined gap.

The operation of the spindle motor having the above-structured dynamic bearing is such that when a voltage is applied to the coil of the stator 31 fixed to the sleeve, the shaft 2
A rotational driving force is generated between the rotor hub 30 and the rotor magnet 32 fixed to the rotor 7, whereby the rotor hub 30 and the shaft 27 are rotated. A dynamic pressure is generated between the parts 21-29, whereby the rotation is brought into a non-contact state, thereby realizing stable rotation with low resistance.

In this state, as shown in the figure, the spiral groove 22 for generating the dynamic pressure is formed on the thrust plate 21 after being assembled into the spindle motor, even if the shaft 27 and other rotating members are removed. Only its upper surface can be confirmed from the outside. This surface is a sliding surface for generating dynamic pressure, and is extremely important in terms of accuracy. Therefore, it is difficult to provide a conspicuous identification mark provided on the back surface, and on the contrary, a slight Such identification marks make it difficult to identify them.

That is, according to the conventional technique, even if a thrust plate has been clearly identified in the machining process, the identification of the groove is not visible after the thrust plate has been assembled. In the process, there was a problem that a defect was found due to erroneous assembling, or that the defect was found after shipping, thereby impairing reliability. For this reason, a technology that can solve these problems has been demanded.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks of the conventional method, and it is necessary to look only at the sliding surface of a grooved dynamic pressure generating member. , The depth of the dynamic pressure generating groove built into the bearing,
An object of the present invention is to provide a simple display method in which specifications unique to the groove, such as the number, width, size, and inclination, can be easily visually identified and managed by an identification pattern assigned to the groove.

[0012]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by further providing an identifiable deep groove having a different form according to each groove specification inside a groove for generating dynamic pressure. Specifically, it includes the following contents. That is, the present invention according to claim 1 includes two members which are opposed to each other so as to be relatively rotatable with a predetermined gap therebetween, and a groove is provided on the opposed surface of one of the members, and a relative gap between the two members is provided. During rotation,
By generating a dynamic pressure of gas or fluid by the action of the groove, in a dynamic pressure bearing configured to keep the two members in a non-contact state, a deep groove dug deeper on the bottom surface of the groove. , Characterized in that the corners are defined by steep edges so as to be distinguishable from the bottom surface.

A dynamic pressure bearing according to a second aspect of the present invention is characterized in that the dynamic pressure generating groove in which the deep groove is formed is provided on a thrust plate constituting a thrust dynamic pressure bearing.

According to a third aspect of the present invention, in the dynamic pressure bearing according to the present invention, the number of the deep grooves is singular or plural, and the continuous form of the deep grooves is a dot, an intermittent streak, or a continuous streak. Wherein the shape of the deep groove is selected from linear, curved, circular, or any combination thereof, and the distribution of the deep groove is concentric,
It is characterized by being selected from spiral, parallel, and radial.

According to a fourth aspect of the present invention, in the dynamic pressure bearing according to the present invention, the deep groove is a continuous streak-shaped deep groove, wherein
When a plurality of grooves are repeatedly provided in one dynamic pressure generating groove, the repetition pitch of the plurality of deep grooves is P, and the width of the deep groove included in the pitch P is W
Where W / P is 0.4 or less.

According to a fifth aspect of the present invention, in the dynamic pressure bearing according to the present invention, the deep groove is a dotted or intermittent streak-like deep groove, which is repeatedly formed in one dynamic pressure generating groove. In a case where R / S is 0.4 or less, when the area of one dynamic pressure generating groove is S and the total area of deep grooves formed in the groove is R, It is characterized by having.

According to a sixth aspect of the present invention, in the dynamic pressure bearing, the depth of the groove for generating the dynamic pressure is 0.2 μm or more and 5 μm or less.

In the dynamic pressure bearing according to the present invention, in the case where the groove for generating the dynamic pressure is formed by scanning the laser beam a plurality of times, the moving pitch of the laser beam may be set to the groove. The deep groove is formed at the same time when the groove is formed by setting the pitch so that a part of the beam diameter on the laser beam irradiation surface overlaps.

The dynamic pressure bearing according to the present invention as set forth in claim 8, wherein the deep groove is formed by an additional step such as laser irradiation after the groove for generating the dynamic pressure is formed. Features.

A dynamic pressure bearing according to a ninth aspect of the present invention is characterized in that the material of the member in which the groove for generating the dynamic pressure is formed is ceramics.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a dynamic pressure bearing according to the present invention will be described below with reference to the drawings. FIG.
FIG. 2 shows a dynamic pressure thrust plate on which grooves are formed according to the first embodiment of the present invention. As described above, the thrust plate is generally provided with a plurality of spiral grooves having a constant inclination with respect to the circumferential direction, and the action of the grooves allows a gas such as air, or a fluid such as oil to rotate with the rotating member. Conduction is made between the fixed members, and the members are kept in a non-contact state by utilizing dynamic pressure generated at that time.

In the drawing, 1 is a thrust plate, 2 is a spiral groove provided on the thrust plate 1, 3 is a deep groove, and this deep groove 3 is a deeper groove provided on the bottom surface of the spiral groove 2. It is dug in a concentric streak through the plurality of spiral grooves on 1.

One of the methods for processing the spiral groove 2 on the surface of the thrust plate 1 is laser processing. This method
The spiral groove portion to be processed on the thrust plate 1 is covered with a mask provided with a slit-shaped gap only, and a laser beam is irradiated thereon, thereby selectively selecting the material of the surface of the thrust plate 1 in the masking gap portion. The groove 2 is formed by digging down only that portion. In the groove processing by this method, a certain depth can be processed by one beam irradiation. Usually, the same position is irradiated a plurality of times, and the groove is formed stepwise until a groove having a predetermined depth is obtained. The width of the beam for this processing is about 0.2-1.
Therefore, to process the spiral groove, the beam irradiation position is moved and scanning is performed a plurality of times to complete the spiral groove. In general, the depth of the groove for generating dynamic pressure (depth indicated by d in FIG. 4B) is set to 0.1 as described above.
A thickness of 2 μm to 5 μm is suitable for generating a dynamic pressure.

The deep groove 3 is formed by forming a deeper groove deeper in the bottom of the groove 2 formed as described above. The advantage of this embodiment is that In processing the groove 2 by such beam irradiation, the groove 2 can be used as it is for the processing of the deep groove 3 and both can be processed simultaneously. That is, when the beam position is moved in order to machine the entire spiral groove width, the beam diameter applied to the machined surface is moved at a pitch that overlaps, for example, by 20% before and after the movement. Assuming that the beam diameter is 1 mm, the overlapping portion.
2 mm width will receive two beam irradiations,
A groove having a depth twice as large as that of the other beam processing portions will be formed. The concentric deep grooves as shown in this embodiment can be easily formed by moving the laser beam irradiation position concentrically. That is, by using the above-described means, the deep groove for identification can be easily formed by only a slight adjustment in the conventional dynamic pressure generating groove forming process without adding a process for itself. Can be very advantageous

Since the deep groove 3 formed as a result of such processing has a sharp edge at a corner which is a boundary with the spiral groove 2 which is a groove portion for generating dynamic pressure, light is applied to the corner. The boundary muscle can be easily identified by visual inspection. This is because the portion of the deep groove 3 looks dark because it is deep, and the edge of the deep groove 3 on the bottom surface of the spiral groove 2 appears linearly and rises.

As described above, the floating force of the dynamic pressure bearing changes depending on the depth of the dynamic pressure generating groove. FIG. 2A schematically shows a groove 2 formed on the surface of the thrust plate 1 and a concentric striped deep groove 3 formed on the bottom surface of the groove 2 as shown in FIG. It is. FIG. 2 (b) is a view of A in FIG. 2 (a).
This is a cross section taken along the axis of the thrust plate 1 orthogonal to the deep grooves 3 arranged concentrically.

According to an experiment conducted by the inventors regarding the influence of the provision of the deep groove portion 3 on the levitation force of the bearing, according to an experiment conducted by the present inventors, in FIG. Where P is the width of the groove included therein and W is 0.4 or less, it has been found that if W / P is 0.4 or less, the effect of the deep groove on the levitation force can be almost ignored. . From this, for example, W / P is set to 0.
Even if two types are provided, i.e., one in which the width ratio of the deep groove portion 3 is very small, and one in which the W / P is 0.4, that is, the width ratio of the deep groove portion 3 is made high, The space between the two can also be visually identified.

In this embodiment, a plurality of stripe-shaped deep grooves 3 are provided concentrically, but they may be provided spirally instead of concentrically. Further, the number of the deep grooves 3 is not necessarily plural, and for example, even if only one passing through the approximate center portion of the spiral groove 1 for generating dynamic pressure is provided, it is sufficient if it can be identified. . Also,
This makes it possible to distinguish between a single case and a plurality of cases, thereby increasing the types of identification.

Next, a dynamic pressure bearing according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 shows a thrust plate according to the present embodiment. In the figure, reference numeral 11 denotes a thrust plate, 12 denotes a spiral dynamic pressure generating groove provided in the thrust plate 11, and 13 denotes a spiral dynamic pressure generation groove. The deep groove 13 is dug deeper into the bottom surface of the groove 12, and the deep groove 13 is dug in a parallel straight line through the plurality of spiral grooves 12 on the thrust plate 11.

Another method for providing spiral grooves in the thrust plate is a shot blast method. In this method, fine particles such as alumina particles are sprayed from the outside of the thrust plate 11 masked in the same manner as in the previous embodiment at a high speed, so that the thrust plate 1 in the gap portion of the masking is sprayed.
The material on one surface is selectively removed, and only that portion is dug down to form a groove. In the present embodiment, the spiral groove 12 processed in this manner is further irradiated with a laser beam in a straight line and at a predetermined pitch in parallel with the bottom surface of the spiral groove 12, whereby the thrust plate 11 is irradiated. A plurality of parallel rows of deep grooves 13 are formed in all the grooves 12 provided on the surface of the substrate.

In such a deep groove processing, a very narrow deep groove 13 is formed by reducing the diameter of a laser beam to be irradiated.
Since the pitch of the deep groove 13 is set to P and the width of the groove included therein is set to W, as described in the above embodiment, for example, W / P between 0.1 (small width ratio) and 0.4 (large width ratio)
If two types are provided, it is possible to distinguish between the two.

In addition to the above embodiments, the concentric deep groove is provided for the beam machining method and the deep groove is provided for the blast method in parallel. However, these combinations are of course optional. . According to the above two embodiments, five types of different groove identification patterns can already be provided by a combination including two types of deep grooves, two types of deep grooves (concentric and parallel), and no deep grooves. The space between them can be visually identified. In addition to this, as described in the above embodiment, singular / plural combinations, for example, by making the direction of the deep groove radial, or by moving the beam following the waveform to make the deep groove a streak of the waveform, It is very easy to increase the types of visual identification.

There are other methods for processing the spiral groove, such as etching and electrical discharge machining, and the deep groove can be processed by these other methods or by combining them. The shape of the streaks can be arbitrarily determined according to a method using a pattern such as electric discharge machining.

In addition to the blast method as in the second embodiment, when a groove for generating dynamic pressure is first formed and then a deep groove is formed by additional means, for example, beam irradiation, the deep groove is The present invention is not limited to the continuous streak-like pattern as in the first embodiment. For example, a discontinuous pattern such as a dot pattern, a broken line pattern, and a staggered pattern can be formed, and more different recognition patterns can be provided. it can. By utilizing these, it becomes possible to assign these recognition patterns for identifying more types of dynamic pressure groove specifications.

When the deep groove is intermittent, for example, in the shape of a dot, a broken line, or a staggered pattern, based on the same concept as described above, the area of one groove for generating a dynamic pressure is S, and the area of one groove for generating the dynamic pressure is S. Assuming that the total area of the deep grooves formed inside is R, if R / S is 0.4 or less, the influence of the provision of the deep grooves on the floating force of the dynamic pressure portion is almost ignored. Can be.

Although each of the above embodiments relates to a spiral groove of a dynamic pressure thrust plate, the present invention can be similarly applied to a radial dynamic pressure dynamic pressure member if necessary. That is, for example, in order to distinguish the groove depth of the dynamic pressure bearing shaft provided with a groove for radial dynamic pressure generation,
A deep groove portion is provided in the groove, and the groove width, direction, and the like can be used for identification. In the groove provided in the radial dynamic pressure part, in addition to the spiral shape, a herringbone shape, a linear shape parallel to the axial direction, etc. are known,
The same applies to these grooves.

As the material of each of the dynamic pressure generating members, stainless steel or the like is used. From the viewpoint of reliability and durability, ceramics having high rigidity and excellent wear resistance are used. Is preferred.

[0038]

By using the bearing member provided with the dynamic pressure generating groove provided with the deep groove according to the present invention, even after the member is incorporated in a spindle motor or the like,
The specifications of the groove can be easily identified, and the problem of bearing levitation force failure due to erroneous assembly and a decrease in product reliability can be avoided in advance. The deep groove can be easily recognized by a visual check of the sliding surface that generates the dynamic pressure.

The deep groove for identification according to the present invention can be easily formed by using a conventional technique such as laser beam irradiation. In particular, when the dynamic pressure generating groove itself is formed by laser processing, the laser beam Advantageously, when moving the irradiation position, the deep groove can be formed simultaneously by overlapping a part of the irradiation.

Further, the deep groove for identification according to the present invention can be combined in various ways with the width and the streak shape of the deep groove. By allocating to each groove, the specifications of the groove can be easily identified visually.

Further, by providing a dynamic pressure generating groove having a deep groove according to the present invention in a ceramic bearing member,
It is possible to provide a bearing that is easy to identify groove specifications and has excellent durability.

[Brief description of the drawings]

FIG. 1 is a perspective view of a thrust plate of a dynamic pressure bearing with an identification groove according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing specifications of an identification groove of the thrust plate shown in FIG.

FIG. 3 is a perspective view of a thrust plate of a hydrodynamic bearing with an identification groove according to another embodiment of the present invention.

FIG. 4 is an explanatory view showing a dynamic pressure generating groove of a thrust plate of a conventional dynamic pressure bearing.

FIG. 5 is a sectional view of a spindle motor incorporating the thrust plate of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dynamic pressure bearing thrust plate 2 Spiral groove for generating dynamic pressure 3 Deep groove for identification 11 Dynamic pressure bearing thrust plate 12 Spiral groove for generating dynamic pressure 13 Deep groove for identification

Continued on the front page (72) Inventor Kaoru Murabe 1-1-1, Koyokita-Kita, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works F-term (reference) 3J011 AA04 AA20 BA08 CA03 DA02

Claims (9)

[Claims] 1. A member comprising two members opposed to each other so as to be relatively rotatable with a predetermined gap therebetween, and a groove is provided in the opposed surface of one member, and when the two members are relatively rotated, gas or gas in the groove is provided. In the hydrodynamic bearing configured to keep the two members in a non-contact state by a fluid dynamic pressure generating action, a corner portion is steeply formed on a bottom surface of the dynamic pressure generating groove so as to be distinguishable from the bottom surface. A hydrodynamic bearing characterized by forming a deep groove dug deeper by partitioning by a sharp edge. 2. The dynamic pressure bearing according to claim 1, wherein the dynamic pressure generating groove in which the deep groove is formed is provided in a thrust plate constituting a thrust dynamic pressure bearing. 3. The number of the deep grooves is selected singly or plurally, and the continuous forms of the deep grooves are dot-like, intermittent streak-like,
Or selected from any of continuous streaks, the shape of the deep groove is selected from linear, curved, circular, or any combination thereof, and the distribution of the deep groove is concentric, spiral The dynamic pressure bearing according to claim 1, wherein the dynamic pressure bearing is selected from one of a parallel shape, a parallel shape, and a radial shape. 4. In the case where the deep groove is a continuous streak-like deep groove, and a plurality of continuous streak-like deep grooves are provided on the bottom surface of one dynamic pressure generation groove, the plurality of deep grooves are provided. Is P, and the width of the deep groove included in the pitch P is W, W / P is 0.4
The dynamic pressure bearing according to claim 1 or 3, wherein: 5. In the case where the deep groove is a point-like or intermittent streak-like deep groove, and a plurality of such grooves are provided on the bottom surface of one dynamic pressure generating groove, the one dynamic pressure generating groove is provided. Assuming that the area of the bottom surface of the groove is S and the total area of the deep groove portion occupying the bottom surface of the groove for generating dynamic pressure is R, R / S is equal to 0.1.
The dynamic pressure bearing according to claim 1 or 3, wherein the number is 4 or less. 6. The dynamic pressure according to claim 1, wherein a depth of the groove for generating dynamic pressure is not less than 0.2 μm and not more than 5 μm suitable for dynamic pressure. bearing. 7. When forming the groove for generating dynamic pressure by scanning a plurality of times by laser beam irradiation,
The deep groove is formed simultaneously with the formation of the groove by setting the movement pitch of the laser beam to a pitch at which a part of the laser beam diameter on the laser beam irradiation surface of the groove overlaps. , Claim 1
The dynamic pressure bearing according to claim 4. 8. The dynamic pressure bearing according to claim 1, wherein the deep groove is formed after the groove for generating the dynamic pressure is formed. 9. The dynamic pressure bearing according to claim 1, wherein a material of a member in which the groove for generating the dynamic pressure is formed is ceramics.