JPH0811833B2 - Grooving device for hydrodynamic bearing - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a groove processing device for a dynamic pressure bearing.

2. Description of the Related Art Conventional technology and its problems As a method of forming a groove on the surface of a shaft portion or a receiving portion of a dynamic pressure bearing, a photoetching method using a film mask is known. For example, in the case of processing a spiral groove on the surface of the sphere of the shaft part of a spherical dynamic pressure bearing, after coating the surface of the sphere with photoresist, a hemispherical film mask was exposed and the mask was removed. After that, the groove is formed by etching. However, the photoetching method using a film mask has the following problems. First, the life of the film mask is short and many masks are required. Further, if the size of the sphere or the groove pattern changes, it is necessary to manufacture a new mask. To manufacture a film mask, there are a method of forming a groove pattern on a hemispherically formed film and a method of forming a groove pattern on a flat film and then forming it into a hemispherical shape. However, in the case of the former, it is difficult to accurately form a groove pattern in a hemispherically shaped film. In the case of the latter, it is necessary to form a groove pattern in a flat film in consideration of deformation so that a desired pattern can be obtained when forming into a hemisphere, but this is extremely difficult. There is a possibility that a defective shape may occur due to uneven deformation when forming into a hemispherical shape. Therefore, in either case, it is difficult to form the groove pattern accurately. Further, the photoresist film may be peeled off when the film mask is covered or removed.

An object of the present invention is to provide a groove processing device for a dynamic pressure bearing that solves all the above problems.

SUMMARY OF THE INVENTION An apparatus according to the present invention comprises a workpiece driving device for holding a workpiece having a photoresist coated on its surface and giving movement to the workpiece, and a laser for the photoresist on the surface of the workpiece. An irradiation device for irradiating light and a control device for controlling the workpiece driving device and the irradiation device based on numerical information about the groove pattern so that a desired area of the photoresist is irradiated with the laser light are provided. There is something.

Practical Example FIG. 1 shows an example of a groove processing device, and FIG. 2 shows an example of a spherical dynamic pressure bearing.

The bearing shown in FIG. 2 has a shaft portion (12) integrally formed with a spherical body (11) at the lower end of an upright shaft (10) and a hemispherical concave surface (13) for receiving the lower half of the spherical body (11). It has a receiving part (14). The axis (A) of the shaft (12) is the center (O) of the sphere (11).
A plurality of shallow spiral grooves (15) are formed at regular intervals on the lower half surface of the sphere (11). Then, the rotation of the shaft (12) causes a dynamic pressure to be generated in the fluid (lubricant) due to the pumping action of the groove (15) so that the spherical body (11) is levitated and supported by the concave surface (13) in a non-contact manner. It has become.

FIG. 3 shows an enlarged view of the spherical body (11) of the shaft portion (12) of the bearing shown in FIG.
As shown in the figure, the axis line (A) of the shaft part (12) is the original line,
Spherical polar coordinates whose origin is the center (O) of the sphere (11) are defined. In FIG. 4, P is a point on the surface of the sphere (11), r is the radius of spherical polar coordinates, θ is the zenith angle of the same coordinates, and φ is the azimuth angle of the same coordinates. A point P on the surface of the sphere (11) is represented by spherical polar coordinates (r, θ, φ). Since the radius r is constant on the surface of the sphere (11), the point P can be represented by the zenith angle θ and the azimuth angle φ. When the pattern of the groove (15) on the surface of the sphere (11) is expressed by the zenith angle θ and the azimuth angle φ,
It looks like Figure 5. In the figure, (G1) to (G12)
Indicates the groove (15) (groove), (H1) to (H12) indicates the groove (1
It represents the part of the hill (16) (hill part) between 5). Further, α is the spiral angle of the groove (15). In FIG. 3, the groove (15) is formed at a portion where the zenith angle θ is between θ1 and θ3. R1 is a horizon connecting the points of zenith angle θ = θ1 on the surface of the sphere (11), and R3 is a horizon connecting the points of zenith angle θ = θ3. Also, R2 is the zenith angle θ = θ2 (θ1
It is a horizon that connects points <θ2 <θ3). The horizon circles R1, R2 and R3 in FIG. 3 are straight lines L1 and L2 in FIG.
And L3. In this type of bearing, the ratio of the width of the hill (16) to the width of the groove (15) (hill / groove ratio) is generally 1
Is. Therefore, the zenith angles θ1 and θ at both ends of the groove (15)
3. Given the number of grooves (15) and the spiral angle α, the groove pattern as shown in FIG. 5 is determined. Also, the hill /
Even if the groove ratio is other than 1, if the hill / groove ratio is given in addition to the above, the groove pattern is determined. As is clear from FIG. 5, grooves (G1) to (G12) and hills (H1) to (H12) appear alternately on the horizon between the zenith angles θ of θ1 and θ3. Then, when the zenith angle θ changes, the grooves (G1) to (G1
The range of azimuth angle φ shown in 2) changes. However, there is a certain relationship between the zenith angle θ and the range of azimuth angles φ in which the grooves (G1) to (G12) appear at that time, and once the groove pattern is determined, the groove (G1 ) ~ (G12)
The range of the azimuth angle φ corresponding to can be obtained.

Grooving equipment consists of the workpiece drive (17) and irradiation equipment (1
8) and these control devices (19).

The workpiece driving device (17) includes a horizontal movable table (20) and a disk-shaped rotary table (which is horizontally mounted on the movable table (20) so as to be rotatable about a vertical axis (Z). 21) and a workpiece holder (22) mounted on the rotary table (21) so as to be rotatable about a horizontal axis (B) which is orthogonal to the central axis (Z) of the rotary table (21) and extends in the radial direction. ) And. The table (21) and the holder (22) are provided with rotary devices (23) and (24) each equipped with a rotary encoder, and these rotary devices (23) and (24) are controlled via an interface (25). It is connected to the device (19). The holder (22) is preferably movable with respect to the table (21) in a direction parallel to its central axis of rotation (B), the moving device for this being also connected to the control device (19). . The movable table (20) is also preferably two horizontal axes (X) (Y) which are orthogonal to each other in the vertical direction.
The mobile device for this purpose is also connected to the control device (19).

The irradiation device (18) includes a laser device (26) and its power supply (27), a lens (28) for condensing laser light, and an electronic shutter (29). The power supply (27) and shutter (29). ) Is connected to the control device (19) via the interface (25). The optical axis (C) of the laser device (26) is parallel to the axis (Y).

As will be described later, the control device (19) controls the workpiece driving device (17) and the irradiation device (18) based on numerical information regarding the groove pattern, and includes a microcomputer. Further, a CRT display (30) and the like are connected to the control device (19).

When the groove (15) of the shaft portion (12) of the bearing shown in FIG. 2 is machined, first, the controller (19) controls the zenith angles θ1 and θ3 at both ends of the groove (15), the number of grooves (15) and Enter the spiral angle α as well as the hill / groove ratio. Then, the control device (19) determines the pattern of the groove (15) as shown in FIG. 5 from these information, and based on this, the workpiece drive device (17) as described later.
And controlling the irradiation device (18).

On the other hand, the surface of the spherical body (11) of the material of the shaft portion (12) of the bearing is coated with, for example, a bodily type photoresist, and this is applied to the holder (22) so that the axis (A) and the axis (B) coincide with each other. Install. Further, the position of the shaft portion (12) is adjusted so that the center (O) of the sphere (11) is on the axis (Z). Furthermore, the heights of the axis (B) and the optical axis (C) are the same, and the optical axis (C)
So that the ball passes through the center (O) of the sphere (11) (21)
Adjust the position of.

When the table (21) is rotated in this state,
The angle (irradiation angle) θ between the axis (A) and the optical axis (C) changes, but the optical axis (C) always passes through the center (O) of the sphere (11), so the optical axis (C) is the sphere. It intersects the photoresist surface of (11) at a right angle at a point P. Hereinafter, this point P is referred to as an irradiation point. The irradiation point P is irradiated with laser light only while the shutter (29) is open. If the irradiation point P is the point P in FIG. 4, the irradiation angle θ corresponds to the zenith angle θ. The rotation angle φ of the holder (22) around the axis (B), that is, the rotation angle φ of the sphere (11) around the axis (A) corresponds to the azimuth angle φ.

Holder (22) with rotating table (21) stopped
The irradiation point P moves on one horizon circle by rotating once. By appropriately opening and closing the shutter (29) during this time, it is possible to irradiate and expose the laser beam to an arbitrary range on this horizon. Then, by repeating such an operation while gradually changing the irradiation angle θ, it is possible to irradiate and expose a desired range of the photo resist surface with laser light.

The first step is to expose the photoresist in this way.
Is the method. Hereinafter, the first method will be described in more detail.

First, the rotary table (2
While stopping 1), the rotation of the holder (22) is stopped at the origin so that the rotation angle φ becomes zero. Controller (1
9) is θ = θ1 from the groove (15) pattern obtained earlier.
The range of φ corresponding to the groove portions (G1) to (G12) at is obtained. Then, the holder (22) is rotated once, and the shutter (29) is opened only while φ is in the range corresponding to the groove portions (G1) to (G12). As a result, only the groove portions (G1) to (G12) on the horizon R1 are irradiated with the laser light and exposed. When the holder (22) makes one rotation, the rotary table (21) is rotated so as to increase the irradiation angle θ, and then stopped. At this θ, the groove portions (G1) to (G12).
After obtaining the range of φ corresponding to, the holder (22) is rotated once while controlling the shutter (29) in the same manner as above. Hereinafter, while changing the irradiation angle θ by the same angle,
The same operation is repeated until becomes θ3. As a result, all the groove portions (G1) to (G12) in FIG. 5 are exposed. In addition,
The diameter of the horizon on the surface of the sphere (11) increases as the zenith angle θ increases. Therefore, if the rotation speed of the holder (22) is constant even if the irradiation angle θ changes, the peripheral speed of the irradiation point P increases as θ increases, and conversely, the exposure time increases as θ increases. It gets shorter. Therefore, θ
It is desirable to decrease the rotation speed as θ increases so that the exposure time at each point becomes the same, that is, the peripheral speed becomes the same, even when is changed.

By simultaneously rotating the rotary table (21) and the holder (22) at an appropriate speed, the irradiation point P can be moved along an arbitrary straight line or curved line in FIG. At this time, by moving the irradiation point P along the straight line or the curved line with the shutter (29) open, all the points on the irradiation point P can be irradiated with laser light for exposure. Then, by gradually shifting such a straight line or a curved line, it is possible to irradiate a laser beam on an arbitrary area of the photoresist surface for exposure.

The second step is to expose the photoresist in this procedure.
Is the method. Hereinafter, the second method will be described in more detail.

First, the rotary table (21) and the holder (22) are stopped so that the irradiation point P comes to the point P1 of the first groove portion (G1) in FIG. Then, with the shutter (29) open,
The rotary table (21) and the holder (22) are rotated so that the irradiation point P moves along the straight line T1 from P1 to P2 to P3. As a result, all points on the straight line T1 are irradiated with laser light and exposed. Next, the rotary table (21) and the holder (22) are rotated so that the irradiation point P moves in the opposite direction on a straight line that is slightly larger than T1 and is parallel to this, and all points on this straight line are rotated. To expose. Such an operation is repeated, and finally the irradiation point P is a straight line T2.
By rotating the rotary table (21) and the holder (22) so as to move along, all the points on the first groove part (G1) are exposed. And the remaining groove (G2) ~
By repeating the same operation for (G12), all the groove portions (G1) to (G12) in FIG. 5 can be exposed. In the above straight lines T1 to T2, the controller (19) has a groove (15).
It can be automatically calculated from the pattern. In the case of the groove (15) pattern as shown in Fig. 5, the rotary table (21)
By keeping the rotation speed ratio of the holder (22) and
The irradiation point P can be moved along the straight lines T1 and T2. If the straight lines T1 and T2 are determined by shifting φ by a constant amount, the interval between the straight lines T1 and T2 becomes smaller as θ becomes smaller. Therefore, if the rotation speeds of the rotary table (21) and the holder (22) are always constant, the exposure density in the small θ range becomes large. In order to make the exposure density of the entire grooves (G1) to (G12) almost constant, the rotation speeds of the rotary table (21) and holder (22) should be large in the small θ range and small in the large θ range. It is desirable to control the rotation speed of the continuous or stepwise.

The above-mentioned device can of course be used for processing grooves other than the spherical body of the shaft portion of the spherical dynamic pressure bearing.

FIG. 6 shows a spherical dynamic pressure bearing which is slightly different from FIG.
In the case of this bearing, a plurality of shallow spiral grooves (31) are provided on the concave surface (13) of the receiving portion (14), and the spherical body (11)
No groove is provided on the surface of. The axis (A) of the receiving portion (14) passes through the center (O) of the concave surface (13). Others are the same as in the case of FIG. 2, and the same portions are denoted by the same reference numerals.

The groove (31) of the concave surface (13) of the receiving portion (14) can be represented by the zenith angle θ and the azimuth angle φ in spherical polar coordinates, as in FIG.

When machining the groove (31) of the receiving part (14) of FIG.
As shown in the figure, a concave surface (13) of the material of the receiving portion (14) is coated with, for example, a bosiform photoresist and attached to the holder (22) so that the axis (A) and the axis (B) are aligned. Further, the position of the receiving portion (14) is adjusted so that the center (O) of the concave surface (13) is on the axis (Z). Furthermore, the heights of the axis (B) and the optical axis (C) are the same, and the optical axis (C) is concave (13).
Adjust the position of the table (21) so that it passes through the center (O) of the table. Then, as in the case of FIG. 1, the groove (31) is exposed by one of two methods.

FIG. 8 shows a journal dynamic pressure bearing. This bearing is
It consists of a shaft part (32) and a cylindrical receiving part (33) that receives it, and a plurality of shallow spiral grooves (34) are evenly spaced on the surface of the shaft part (32) that fits into the receiving part (33). Has been formed. A point on the surface of the shaft portion (32) can be represented by a position x in the axial direction and a rotation angle φ about the axis (A). Therefore, the pattern of the groove (34) can also be represented by x and φ, as shown in FIG.

When machining the groove (34) of the shaft part (32) in FIG.
As shown in the figure, for example, a positive photoresist is applied to the surface of the material of the shaft part (32), and the axis (A) is the axis (B).
Install it in the holder (22) so that it matches. Further, the heights of the axis (A) and the optical axis (C) are the same, and the axis (A)
Adjust the position of the table (21) so that is parallel to the axis (X). On the other hand, the control device (19) is input with the numerical information necessary for determining the pattern of the groove (34) as shown in FIG. Then, the control device (19) controls the workpiece driving device (17) and the irradiation device (18) by the following three methods based on these pieces of information.

The first method is to divide the surface of the shaft portion (32) into a large number of circles centered on the axis (A) and to divide the grooves (3
The part corresponding to 4) is exposed. That is,
First, the holder (22) or the movable table (20) is moved in a direction parallel to the axis (X), so that the shaft portion (32) is positioned so that the irradiation point P is located at the position of x1. Then, the holder (22) is rotated once around the axis (B) while controlling the shutter (29) so that the portion corresponding to the circular groove (34) is irradiated. Next, after the shaft portion (32) is moved in the axis (X) direction so as to change x slightly and stopped, the holder (22) is rotated once while controlling the shutter (29). Then, the operation of gradually moving the shaft portion (32) in the direction of the axis (A) and then rotating it once is repeated, and finally the holder is moved so that the irradiation point P moves on the circle of x = x2. Rotate (22) once. As a result, the entire groove (G) in FIG. 9 is exposed.

In the second method, the surface of the shaft portion (32) is divided into a large number of straight lines parallel to the axis (A) as described below, and the grooves (34) of the respective straight lines are divided.
The portion corresponding to is exposed. That is, first, the holder (22) is positioned so that the irradiation point P comes to one point on x = x1 in FIG. Then, while the rotation of the holder (22) is stopped, it is moved in the axis (X) direction to x = x2. At this time, the shutter (29) is controlled so that only the position corresponding to the linear groove (34) is exposed. Next, after slightly rotating the holder (22), the holder (22)
Is moved in the opposite direction from x = x2 to x = x1.
Then, by repeating such an operation until the holder (22) makes one rotation, all the groove portions (G) in FIG. 9 are exposed.

The third method is to divide the groove (34) into a number of curves in the lengthwise direction, and expose these curves in order to expose the entire portion corresponding to the groove (34). This method is realized by simultaneously rotating the rotary table (21) and the holder (22) at an appropriate speed.

FIG. 11 shows a disk-shaped receiving portion (35) of the dynamic thrust bearing. On the surface of the receiving portion (35), a plurality of shallow spiral grooves (36) are formed at equal intervals within a radius r of r1 to r2. A point on the surface of the receiving portion (35) can be represented by a radius r and a rotation angle φ of the receiving portion (35) about the axis (A). Therefore, the pattern of the groove (36) is also
As shown in Fig. 12, it can be represented by r and φ.

When machining the groove (36) of the receiving part (35) shown in FIG.
As shown in the figure, a positive photoresist, for example, is applied to the surface of the material of the receiving portion (35) and attached to the rotary table (21) so that the axis (A) coincides with the axis (Z). Further, a mirror (37) that intersects the horizontal optical axis (C) at an angle of 45 degrees is fixedly arranged above the turntable (21), and the vertical optical axis (C) reflected thereby is received by the receiving portion (35). Make a right angle with the surface of. Further, the rotary table (21) is positioned so that the vertical optical axis (C) coincides with the axis (Z). On the other hand, the controller (19) is input with numerical information necessary for determining the pattern of the groove (36) as shown in FIG. And
The control device (19) controls the workpiece drive device (17) and the irradiation device (18) by the following two methods based on these pieces of information.

In the method of FIG. 1, the surface of the receiving portion (35) is divided into a large number of concentric circles centering on the axis (A) and the portion corresponding to each circular groove (36) is exposed as follows. It is a thing. That is, first, the movable table (20) is set on the axis (Y) (or the axis (X)).
The receiver (35) is positioned so that the irradiation point P comes to one point on the circle of r1 by moving in the direction parallel to. Then, while controlling the shutter (29) so that the portion corresponding to the circular groove (36) is irradiated, the receiving portion (35) is rotated once around the axis (A). Next, after moving the receiving portion (35) in the axis (Y) (or axis (X)) direction so that r becomes a little larger, the receiving portion (35) is similarly controlled while controlling the shutter (29). Rotate once. Then, by repeating such an operation until the radius r becomes r2, all the groove portions (G) in FIG. 12 are exposed.

The second method is to divide the groove (36) into a large number of curves in the lengthwise direction and expose these curves in order to expose the entire portion corresponding to the groove (36). This method is realized by moving the rotary table (21) linearly in the horizontal direction at an appropriate speed and simultaneously rotating the table at an appropriate speed.

The process after exposing the portion corresponding to the groove of the fault resist as described above is the same as in the ordinary photoetching method.

EFFECTS OF THE INVENTION Since the device according to the present invention has the above-mentioned configuration, the groove can be easily and accurately processed by only inputting the numerical information regarding the groove pattern. For this reason, it is not necessary to use a fort mask as in the conventional case. Therefore, the number of steps is reduced, and the photoresist film is not peeled off by the photomask.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a groove machining apparatus showing an embodiment of the present invention, FIG. 2 is a vertical sectional view of a spherical dynamic pressure bearing, and FIG.
The side view which expands and shows the spherical part of the grooved shaft part of the bearing of the figure, FIG. 4 is the perspective view which shows the spherical polar coordinate provided in the sphere of FIG. 3, FIG. 5 is the sphere of FIG. FIG. 6 is a diagram showing the groove pattern of FIG. 6 in polar coordinates, FIG. 6 is a vertical cross-sectional view showing the grooved receiving portion of the spherical dynamic pressure bearing, and FIG. 7 is a state showing the groove of the receiving portion shown in FIG. A drawing corresponding to FIG. 1, FIG. 8 is a vertical sectional view showing a journal dynamic pressure bearing, FIG. 9 is a view showing the groove pattern of the grooved shaft portion of the bearing of FIG. 8 in polar coordinates, and FIG. A plan view of the main part of the groove processing device showing the state when processing the groove of the shaft part of the figure, FIG. 11 is a plan view showing the disk-shaped grooved receiving part of the thrust dynamic pressure bearing, and FIG. FIG. 11 is a view showing the groove pattern of the grooved receiving portion of the bearing of FIG. 11 in polar coordinates, and FIG. 13 is a side view showing the main part of the groove processing device when processing the groove of the receiving portion of FIG. (12) …… Shaft, (14) …… Receiving part, (15) …… Groove, (1
7) …… Workpiece drive, (18) …… Irradiator, (19)
...... Control device, (31) …… Groove, (32) …… Shaft, (34)
…… Groove, (35) …… Receiving part, (36) …… Groove.

Claims (1)

[Claims] 1. A workpiece driving device for holding a workpiece having a photoresist coated on its surface and giving movement to the workpiece, and an irradiation device for irradiating the photoresist on the surface of the workpiece with laser light. A groove processing apparatus for a dynamic pressure bearing, comprising: a workpiece driving device and a control device that controls the irradiation device based on numerical information regarding a groove pattern so that a desired area of a photoresist is irradiated with laser light.