JPS63103086A - Grooving device for dynamic pressure bearing - Google Patents

Abstract

PURPOSE:To execute simple and exact grooving without using a photomask by executing control in accordance with the numerical information on the pattern of grooves so as to project laser light to the desired range of a photoresist coated on the surface of a work piece. CONSTITUTION:An angle theta between the axial line A in the shaft part 12 of a bearing and the optical axis C of the laser light changes but the optical axis C intersects always perpendicularly with the photoresist surface of a spherical body 11 at one point P when a table 21 is horizontally rotated. The rotating angle phi of the spherical body 11 around the horizontal axis B of the holder 22 in the shaft part 12 corresponds to an azimuth. A controller 19 of such constitution rotates the holder 22 by one turn to move the projection point P and projects the laser light from a laser light device thereto in accordance with the numerical information on the pattern of the grooves while the turn table 21 is held stopped. The above-mentioned operation is successively repeated while the projection angle theta is changed each slightly to form the spiral grooves 15 on the spherical body 11. The grooving is thereby simply and exactly executed without using the photomask.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a groove machining device for a hydrodynamic bearing.

BACKGROUND ART Conventional techniques and their problems A photoetching method using a film mask is known as a method for forming grooves on the surface of the shaft or bearing of a hydrodynamic bearing. For example, when machining a spiral groove on the surface of a sphere on the shaft of a spherical hydrodynamic bearing, first coat the surface of the sphere with photoresist, cover it with a hemispherical film mask, expose it, and remove the mask. Afterwards, grooves are formed by etching. However, the photoetching method using a film mask has the following problems. First, film masks have a short lifespan and require a large number of masks.

Additionally, if the dimensions of the sphere or the pattern of the vortices change, a new mask will need to be manufactured. There are two methods for manufacturing a film mask: one method is to form a groove pattern on a hemispherical film, and the other is to form a groove pattern on a flat film and then mold it into a hemispherical shape. However, in the former case, it is difficult to accurately form a groove pattern on a hemispherical film.

In addition, in the latter case, it is necessary to form a full pattern on the flat film in anticipation of the deformation valve so that it will form the desired pattern when molded into a hemispherical shape, but this is extremely difficult. However, when forming into a hemispherical shape, uneven deformation may cause shape defects. Therefore, in either case, it is difficult to accurately form the groove pattern. Furthermore, when applying or removing a film mask, there is a risk that the photoresist layer may peel off.

An object of the present invention is to provide a hydrodynamic bearing groove machining device that solves all of the above problems.

Means for Solving the Problems The 5A device according to the present invention includes a workpiece drive device for holding and giving motion to a workpiece whose surface is coated with photoresist, and a workpiece drive device for holding and imparting motion to a workpiece whose surface is coated with photoresist. It is equipped with an irradiation device for irradiating a laser beam, and a control device for controlling a workpiece drive device and an irradiation device based on numerical information regarding the groove pattern so that a desired range of the photoresist is irradiated with the laser beam. It's b.

Embodiment FIG. 1 shows an example of a processing device, and FIG. 2 shows an example of a spherical hydrodynamic bearing.

The bearing shown in Figure 2 has a sphere (11) at the lower end of the upright shaft (10).
and a receiving portion (14) having a hemispherical concave surface (13) for receiving the lower half of the sphere (11).
). The axis (△) of the shaft (12) is the sphere (11
), and a plurality of shallow spiral grooves (15) are formed at equal intervals on the lower half surface of the sphere (11). Then, the groove (
The pumping action of 15) generates dynamic pressure in the fluid (lubricant) to levitate the sphere (11) and support it on the concave surface (13) in a non-contact manner.

FIG. 3 shows an enlarged view of the sphere (11) of the shaft portion (12) of the bearing shown in FIG. 2, and inside the sphere (11),
As shown in FIG. 4, spherical polar coordinates are determined with the axis (A) of the shaft portion (12) as the origin and the center (0) of the sphere (11) as the origin. In Figure 4, P is a sphere (11)
A point on the surface of , r is the radius of the 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). sphere(
Since the radius r is constant on the surface of 11), the point P can be expressed by the zenith angle θ and the azimuth angle φ. sphere(
When the pattern of the grooves (15) on the surface of 11) is expressed by the zenith angle θ and the azimuth angle φ, it becomes as shown in FIG. In the same figure, (G1) to (G12) are the groove (15) portion (groove portion);
(Hl) to (Hl2) represent the part of the hill (16) between the grooves (15). Further, α is the spiral angle of the groove (15).

In Figure 3, the groove (15) has zenith angles θ of 01 and 03.
It is formed in the area between. R1 is within the horizon connecting the points at the zenith angle θ=01 on the surface of the sphere (11), and R3 is within the horizon connecting the points at the zenith angle θ-θ3. Further, R2 is within the horizon connecting the points of zenith angle θ=02 (G1<G2<G3).

Note that R1, R2, and R3 in the horizon in FIG. 3 are straight lines in FIG. 5, and are represented by 1, L2, and L3. In this type of bearing, generally the width of the hill (16) and the full width (15
) has a width ratio (hill/groove ratio) of 1. Therefore, the groove (
15), the number of grooves (15), and the spiral angle α are given, the groove pattern as shown in FIG. 5 is determined. Further, even when the hill/groove ratio is other than 1, the groove pattern is determined if the hill/groove ratio is given in addition to the above. As is clear from FIG. 5, groove portions (G1) to (G12) and hill portions (Hl) to (Hl2) appear alternately on the horizon circle where the zenith angle θ is between 01 and 03. and,
When the zenith angle θ changes, the range of azimuth angles φ in which the grooves (G1) to (G12) appear changes. However, the zenith angle θ
There is a certain relationship between the range of azimuth angle φ in which grooves (G1) to (G12) appear at that time, and once the groove pattern is determined, grooves (G1) to (G 12
) can be found.

The groove machining device includes a workpiece drive device (17) and an irradiation device (1
8) and their control device (19).

The workpiece drive device (17) includes a horizontal moving table (20),
A disc-shaped rotary cheeple (21) mounted horizontally on the movable table (20) so as to be able to rotate around a vertical axis (Z).
and a workpiece holder (2) mounted on the rotary table (21) so as to be rotatable about a horizontal axis (B) extending in the radial direction and perpendicular to the center @ (Z) of the rotary table (21).
2). Table (21) and holder (
22) is a rotating device equipped with a rotary encoder! (
23) and (24) are provided, respectively, and these rotating devices (23) and (24) are connected to the control device (19) via an interface (25). Holder (22
) can preferably be moved relative to the table (21) in a direction parallel to its central axis of rotation (B), and the movement device for this purpose is also connected to the control device (19).

Further, the moving table (20) can also preferably be moved in the vertical direction and in the two horizontal axes (X) and (Y) directions perpendicular to each other, and the moving device for this purpose also includes the tl control device (1
9).

The irradiation device (18) includes a laser device (26), its power source (27), and a lens (2) for condensing the laser beam.
8) and an electronic shutter (29), and the power supply (27) and shutter (29) are connected to the interface (29).
5) to the control device M (19).

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 drive device (17) and the irradiation device (18) based on numerical information regarding the groove pattern, and includes a microcomputer. In addition, the control device ffi (19)
A CRT display (30) or the like is connected to the .

When machining the groove (15) of the shaft portion (12) of the bearing shown in Fig. 2, first, the control device (19) is informed of the zenith angle θ1, G3, the number of grooves (15) at both ends of the groove (15), and the Spiral angle α
As well as hill/i? 4 Enter the ratio. And the control device (
19) derives iM (15) from this information as shown in Figure 5.
), and based on this pattern, the workpiece drive device (17) and irradiation device (18) are controlled as described later.

On the other hand, for example, a positive photoresist is applied to the surface of the spherical body (11) of the shaft part (12) of the bearing, and this is applied to the holder (22) so that the axis (A) coincides with the axis <8>. Install. Also, the center (0) of the sphere (11) is @(Z)
Adjust the position of the shaft (12) so that it is on top. Furthermore, the heights of the axis (B) and the optical axis (C) are the same, and the optical axis (
Adjust the position of the table (21) so that C) passes through the center (0) of the sphere (11).

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 (0) of the sphere (11), so the optical axis (C) It intersects the photoresist surface of the sphere (11) at a right angle at one point P. Hereinafter, this point P will be referred to as the irradiation point.

Then, the irradiation point P is irradiated with laser light only while the shutter (29) is open. Note that if the irradiation point P is the point P in FIG. 4, the irradiation angle θ corresponds to the zenith angle θ. Further, 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 1it (A) corresponds to the azimuth angle φ.

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

The first method is to expose the photoresist using such a procedure. The first method will be explained in more detail below.

First, set the rotary table (21
) is stopped, and the rotation of the holder (22) is stopped at the origin so that the rotation angle φ becomes O. Control device (1
9) is θ=0 from the pattern of the groove (15) found earlier.
1, the range of φ corresponding to the grooves (G1) to (G12) is determined in advance. Then, the holder (22) is rotated once, and the shutter (29) is opened only while φ is within the range corresponding to the grooves (G1) to (G12). This results in
Only the groove portions (G1) to (G12) on the horizon circle R1 are irradiated with the 1-boo light and exposed. Holder (22)
When has made one revolution, rotate the rotary table (21) so that the irradiation angle θ becomes a little larger and stop it, and find the range of φ corresponding to the grooves (G1) to (G12) at this θ. Afterwards, the holder (22) is rotated once while controlling the shutter (29) in the same manner as above. Thereafter, the same operation is repeated while changing the irradiation angle θ by the same angle increments until θ reaches G3. As a result, the groove part (G1
) to (G12> are all exposed. In addition, the sphere (11)
The horizontal diameter of the surface of becomes larger as the zenith angle θ becomes larger. Therefore, even if the illumination angle θ changes, the holder (2
Assuming that the rotational speed in 2) is constant, the circumferential speed of the irradiation point P increases as θ increases, and the exposure time, conversely, becomes
The larger θ becomes, the shorter it becomes. For this reason, it is desirable to reduce the rotational speed as θ increases so that even if θ changes, the exposure time at each point is equal, that is, the circumferential speed is equal.

By simultaneously rotating the rotary table (21) and the holder (22) at an appropriate speed, the irradiation point P can be moved along any straight line or curved line in FIG.

At this time, by moving the irradiation point P along the above straight line or curve with the shutter (29) open,
All points on it can be exposed by irradiating laser light. Then, by gradually shifting such straight lines or curves, it is possible to irradiate and expose an arbitrary range of the photoresist surface with laser light.

The second method is to expose the photoresist using such a procedure. The second method will be explained in more detail below.

First, the irradiation point P is the point P1 of the first groove (G1) in FIG.
Rotating table (21) and holder (2) so that
2) is stopped. Then, with the shutter (29) open, the rotary table (29) is moved so that the irradiation point P moves along the straight line T1 from Pl through P2 to P3.
1) Rotate e and holder (22). This results in
All points on the straight line T1 are irradiated with laser light and exposed.

Next, set the rotary table (
21) and the holder (22) to expose all points on this straight line. By repeating this operation and finally rotating the rotary table (21) and holder (22) so that the irradiation point P moves along the straight line T2, all the points on the first groove (G1) are exposed to light. Then, by repeating the same operation for the remaining grooves (G2) to (G12), all the grooves (G1
) to (G12) can be exposed.

The above straight lines T1 to T2 are connected to the groove (15) by the control device (19).
) can be automatically determined from the pattern.

In the case of a pattern of grooves (15) as shown in Fig. 5, the irradiation point P can be moved along the straight line T1 to T2 by keeping the rotational speed ratio of the rotary table (21) and holder (22) constant. can be done. Note that if the straight lines T1 and T2 are determined by shifting φ by a certain amount, the interval between the straight lines T1 and T2 becomes smaller as θ becomes smaller. Therefore, if the rotational speeds of the rotating daple (21) and the holder (22) are always constant, the exposure density will be high in a small range of θ. In order to make the exposure density of the entire grooves (G1) to (G12) almost constant, the rotary table (21) and the holder (22)
It is desirable to control these rotational speeds continuously or in steps so that the rotational speeds of ) are large in a small range of θ and small in a large range of θ.

Of course, the above-mentioned apparatus can also be used for machining grooves other than spheres in the shaft portion of a spherical hydrodynamic bearing.

FIG. 6 shows a spherical hydrodynamic bearing that is slightly different from FIG. 2. 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), but no grooves are provided on the surface of the spherical body (11). Note that the axis (A) of the receiving portion (14) passes through the center (0) of the concave surface (13). The rest is the same as in FIG. 2, and the same parts are given the same reference numerals.

The groove (31) of the concave surface (13) of this receiving part (14) is the fifth
As in the figure, it can be expressed by the zenith angle θ and the azimuth angle φ of the pitch type coordinates.

When machining the groove (31) of the receiving part (14) in Fig. 6, as shown in Fig. 7, the concave surface (13) of the material of the receiving part (14)
For example, apply a positive photoresist to the axis line (A
) on the holder (22) so that it aligns with the shaft (B). Also, adjust the position of the receiving part (14) so that the center (0) of the concave surface (13) is above @(2). Additionally, the axis (
The heights of B) and optical axis (C) match, and the optical axis (C)
Place the table (2) so that it passes through the center (0) of the concave surface (13).
Adjust the position of 1). And, as in the case of Figure 1,
The groove (31) portion is exposed in one of two ways.

FIG. 8 shows a journal hydrodynamic bearing. This bearing consists of a shaft part (32) and a cylindrical receiving part (33) that receives the shaft part, and has a plurality of shallow spiral grooves (34) on the surface of the shaft part (32) that fits into the receiving part (33). are formed at equal intervals. A point on the surface of the shaft (32) is at a position aX in the axial direction
and a rotation angle φ around the axis ail(A). Therefore, the pattern of the grooves (34) can also be represented by X and φ, as shown in FIG.

When machining the groove (34) of the shaft (32) shown in FIG. 8, as shown in FIG. ) on the holder (22) so that it aligns with the shaft (B). Also, set the table (21
). On the other hand, numerical information necessary for determining the pattern of the grooves (34) as shown in FIG. 9 is input into the control device (19). Based on this information, the control device (19) controls the workpiece drive device (17) and the irradiation device (18) using the following three methods.
I+ control.

The first method is to divide the surface of the shaft (32) into a large number of circles centered on the axis (A), and grooves (3) on each circle.
The portion corresponding to 4) is exposed. That is,
First, move the holder (22) or moving table (20) to the axis (X).
By moving the irradiation point Pffi in a direction parallel to
Position the shaft portion (32) so that it is at position 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, move the shaft part (32) in the direction of the shaft (X) so that X changes a little and stop it, and then similarly rotate the holder (22) once while controlling the shank V ivy (29). . And like this, the shaft part (
32) in the direction of the axis (A) is repeated, and finally, the holder (22) is rotated once so that the irradiation point P moves on the circle of x=x2. As a result, the entire groove (G) in FIG. 9 is exposed.

The second method is to divide the surface of the shaft (32) into a large number of straight lines parallel to the axis (A), and to divide the surface of the shaft (32) into a large number of straight lines parallel to the axis (A),
) is exposed. That is, first, the holder (22) is positioned so that the irradiation point P is at one point on X-xl in FIG. And the holder (22
) with the rotation stopped, move it in the axis (X) direction x-x
Move it to 2. At this time, the shutter (29) is controlled so that only the position corresponding to the groove (34) on the straight line is exposed. Next, after rotating the holder (22) a little, move the holder (22) in the opposite direction from X=X2 to X=
Move it to X1. By repeating this operation until the holder (22) rotates once, the groove (G) in FIG. 9 is completely exposed.

A third method is to divide the groove (34) into a number of curves along its length and expose these curves in sequence, thereby exposing all the portions corresponding to the groove (34). This method is realized by simultaneously rotating the rotary table (21) and the holder (22) at an appropriate speed.

Figure 11 shows the disc-shaped receiving part (35) of the dynamic pressure thrust bearing.
shows. The surface of this receiving part (35) has a plurality of shallow spiral grooves (3G) with a radius r in the range rl to r2.
are formed at equal intervals. A point on the surface of the receiving part (35) can be expressed by the radius r and the rotation angle φ of the receiving part (35) about the axis (A>).
) can also be expressed by r and φ, as shown in FIG.

When machining the groove (36) of the receiving part (35) in Fig. 11,
As shown in FIG. 13, for example, a positive photoresist is applied to the surface of the material of the receiving part (35), and the axis (A) is aligned with the axis (
Attach it to the rotary table (21) so that it matches Z). In addition, there is a horizontal optical axis (C) above the rotary table (21).
1it (37) that intersects at a 45 degree angle with the receiver part (35
) so that it intersects the surface at right angles. In addition, the vertical optical axis (
Rotate the rotary table (21) so that C) is aligned with the axis (Z).
). On the other hand, numerical information necessary for determining the pattern of w4 (3B) as shown in FIG. 12 is input to the control I device (19). And the control unit @ (1
9) uses the following two methods to operate the workpiece drive device (17) and the irradiation vR position (18) based on this information.
) is controlled by ailJ.

The first method is to divide the surface of the receiving part (35) into a number of concentric circles centered on the axis (A) as follows, and ?
14 (36) is exposed. That is, first, move the moving table (20) to the axis (Y) (or axis (
×)) By moving the irradiation point P in a direction parallel to
The receiving part (35) is positioned so as to be at one point on the circle of ffir1. Then, the receiver (35) is rotated once around the axis (A) while controlling the shutter (29) so that the portion corresponding to the groove (36) on the circle is irradiated. Next, attach the receiving part (35) so that r is a little larger.ff1Y)
(or axis (x)) direction, and then similarly rotate the receiving part (35) once while controlling the shutter (29). By repeating this operation until the radius r reaches r2, the groove (G) in FIG. 12 is completely exposed.

The second method is to divide the groove (36) into a number of curves along its length and expose these curves in order to expose all the portions corresponding to the groove (36). This method is realized by linearly moving the rotary table (21) in the horizontal direction at an appropriate speed and simultaneously rotating it at an appropriate speed.

The processing after exposing the portions of the photoresist corresponding to the grooves as described above is the same as in the normal photoetching method.

Effects of the Invention Since the apparatus according to the present invention has the above-described configuration, it is possible to easily and accurately process grooves by simply inputting numerical information regarding the groove pattern. Therefore, there is no need to use a 7 automask as in the prior art, and therefore the number of steps is reduced, and there is no fear that the photoresist film will peel off due to the photomask.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a groove machining device showing an embodiment of the present invention, Fig. 2 is a vertical cross-sectional view of a spherical hydrodynamic bearing, and Fig.
Fig. 4 is a side view showing an enlarged view of the spherical part of the grooved shaft of the bearing shown in Fig. 4; Figure 6 shows the pattern of grooves on a sphere in polar coordinates. Figure 6 is a vertical cross-sectional view showing the groove I 1 receiving part of the spherical hydrodynamic bearing. Figure 7 shows the state when machining the full part of the receiving part in Figure 6. Figure 8 is a vertical sectional view showing a journal dynamic pressure bearing, Figure 9 is a diagram showing the groove pattern of the grooved shaft portion of the bearing in Figure 8 in polar coordinates, and Figure 10 is a diagram equivalent to Figure 1. Fig. 8 shows the condition when machining the groove of the shaft part) Fig. 14 is a plan view of the main part of the processing device, Fig. 11 is a plan view of the disc-shaped grooved receiving part of the thrust dynamic pressure bearing, The figure is a diagram showing the groove pattern of the grooved receiving part of the bearing shown in Fig. 11 in polar coordinates, and Fig. 13 is a side view showing the main parts of the groove machining device used when machining the groove of the receiving part of Fig. 11. be. (12)...Shaft part, (14)...Receiving part, (15)...
...Groove, (17)...Workpiece drive device, (18)...
・Irradiation device, (19)...control device, (31)...
Groove, (32)...Shaft portion, (34)...Groove, (35)
...Receptacle, (36)...Groove. Applicant for the above patents: Koyo Seiko Co., Ltd. Agent: Einosuke Kishimoto (4 others) Figure 1 Figure 2 Figure 4 - Figure i3 Figure 111 Kaoru 1

Claims (1)

[Claims] A workpiece drive device for holding and giving motion to a workpiece whose surface is coated with photoresist, an irradiation device for irradiating laser light to the photoresist on the surface of the workpiece, and a desired photoresist coating. A groove machining device for a hydrodynamic bearing, comprising a control device for controlling a workpiece drive device and an irradiation device based on numerical information regarding a groove pattern so that a laser beam is irradiated within a range of .