JPS63103087A - Grooving device for dynamic pressure bearing - Google Patents

Abstract

PURPOSE:To simply and accurately execute grooving without using a photomask by projecting laser light to a work piece on which a photoresist is coated from the top end of an optical fiber fixed to a cantilever type supporting bar at the time of projecting the laser light to said work piece. CONSTITUTION:The photoresist is coated in a recess 12 of a stock in a resting part 11 of a bearing and the bearing is so mounted to a holder 19 that the axial line A thereof aligns to the axial line B of the holder 19. The position of a moving base 18 is so adjusted that the axial line A of the part 11 aligns in height to the optical axis C of the laser light. The optical axis C intersects orthogonally with the photoresist surface in the recess 12 at one point P when the front end part of the supporting bar for the optical fiber 25 is inserted to the inside of the resting part 11 in the above- mentioned constitution. The moving base 18 is then stopped and in this state, the laser light is projected through the optical fiber 25 while the holder 19 is rotated one turn by a controller 17 in accordance with the numerical information on the pattern of grooves. The above-mentioned operation is executed repeatedly while the projection position is changed each slightly, by which the grooves are successively worked in the recess 12 of the bearing. The grooves of high accuracy are thereby formed.

Description

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

Conventional technology and its problems A photo-etching method using a film mask is a method for forming grooves on the surface of the shaft or bearing of a hydrodynamic bearing.
It has been known. 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 grooves change, a new mask must 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 groove pattern on the flat film in consideration of the deformation force so that it will form the desired pattern when molded into a hemispherical shape, but this is extremely difficult. However, when molding 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 putting on or removing a film mask, there is a risk that the photoresist film will peel off.

In addition, especially in the case of a journal hydrodynamic bearing in which the shaft portion is supported by a cylindrical receiving portion, there are many advantages if grooves can be formed on the inner surface of the receiving portion. For example, the positioning of the shaft and the receiving section is easier than when grooves are formed on the outer periphery of the shaft. Moreover, since the bearing is formed simply by attaching the receiving portion to the housing, it can be handled in the same way as a conventional rolling bearing. However, it is very difficult to form grooves on the inner surface of a cylinder by photoetching, and for this reason, conventionally, grooves have mostly been formed on the surface of the shaft. As a method of machining grooves on the inner surface of a cylinder, methods using machining such as internal turning and plastic working are known. However,
Such machining has problems with accuracy and is not suitable for groove machining of hydrodynamic bearings, where the accuracy of the groove directly affects bearing performance.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydrodynamic bearing groove machining device that solves all of the above-mentioned problems and that can easily machine highly accurate grooves even on concave surfaces such as the inner surface of a cylinder.

Means for Solving the Problems The apparatus according to the present invention is equipped with an irradiation device for irradiating a laser beam onto a photoresist coated on the surface of a workpiece, and this irradiation device is attached to a cantilevered support rod. It is equipped with a fixed optical fiber, and a laser beam is emitted from the tip of the optical fiber.

Embodiment FIG. 1 shows an example of a groove machining device, and FIG. 2 shows an example of a journal dynamic pressure bearing.

The bearing shown in Fig. 2 consists of a shaft part (10) and a cylindrical receiving part (11) that receives the shaft part.
A plurality of shallow double spiral (herringbone) grooves (13) are formed at equal intervals in J (12).

Then, dynamic pressure is generated in the fluid (lubricant) by the pump action of the groove (13) due to the rotation of the shaft (10), and the shaft (10)
is supported on the concave surface (12) in a non-contact manner.

In addition, in FIG. 2, A represents the axis of the receiving part (11). In addition, X represents the position in the axis (A) direction, and the groove (1
3) The position of one end is represented by ×1, the position of the other end is represented by ×3, and the position of the bending point is represented by ×2. R1 is a circle connecting the points X-Xl on the concave surface (12) of the receiving part (11), and R2 is x
= A circle connecting the points x2, 'R3 is a circle connecting the points X-X3.

The point on the concave surface (12) of the receiving part (11) is
1) is expressed by the position X in the axis (A) direction and the rotation angle φ around the axis (A). When the pattern of the grooves (13) on the concave surface (12) is expressed by the position X and the rotation angle φ, it becomes as shown in FIG. In the same figure, (G1) to (GIO
) is the part of groove (13) (groove part), (Hl ) to (H10
) represents the part (hill part) of the hill (14) between the grooves (13). Further, α is the spiral angle of the groove (13). In this type of bearing, the ratio of the width of the hill (14) to the width of the groove (13) (hill/groove ratio) is generally 1. Therefore, the number of grooves (13), the spiral angle α, the position Xi, X2
If x3 and x3 are given, a groove pattern as shown in FIG. 3 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. Note that circles R1, R2, and R3 in FIG. 2 are straight I! in FIG. 1lL1, L2 and L3. As is clear from Fig. 3, on the circle where the position
1') ~ (Hlo>) appear alternately. Then, when the position X changes, the range of rotation angle φ in which the grooves (G1) to (GIO) appear changes. There is a certain relationship between the range of rotation angle φ in which G1) to (G10) appear, and once the pattern of the groove (13) is determined, the grooves (G1) to (G10) are
) can be found.

The groove processing device includes a workpiece drive device (15) and an irradiation device (1
6) and their control device (17).

The workpiece drive device (15) includes a horizontal moving table (18),
A moving table (18) that can rotate around the horizontal axis (B)
and a workpiece holder (19) mounted thereon. The moving table (18) has a horizontal axis (
A moving device (20) is provided for moving in the X> direction, and this moving device (20)
1) is connected to the control device (11). The holder (19) is provided with a rotating bag H (22) for rotating it around the axis (B), and this rotating bag U
(22>) is also connected to the control device (17) via the interface (21).
The moving device for this purpose is also connected to the $ control device (17).

The irradiation device (16) is equipped with a laser device (23), and this laser device (23) is connected to the interface (21).
It is connected to the control device (17) via. The laser device (23) beam @ (C) is parallel to the axis (X), and the workpiece drive device (15) is located at the tip of the laser device (23).
A hollow support rod (24) extending in the axial (X) direction is fixed in a cantilevered manner. An optical fiber (25) for guiding laser light is passed through the support rod (24).

The tip of the support rod (24) is bent at a nearly right angle in the horizontal plane, and a spherical lens (26) is provided at the tip to condense the laser beam that has passed through the optical fiber (25).
) is installed.

As will be described later, the control device (17) controls the workpiece drive device (15) and the irradiation device (16) based on numerical information regarding the groove pattern, and is equipped with a microcomputer. Further, a CRT display (27) and the like are connected to the control device "a" (17).

When machining the groove (13) in the receiving part (11) of the bearing shown in Fig. 2, first, the number of WI# (15),
Input the positions x1, x3, and x2 of both ends and bending points, the spiral angle α, and the hill/groove ratio.

Then, the control device (17) determines the pattern of the groove (13) as shown in FIG. 3 from this information, and based on this, the workpiece drive device (15) and the irradiation device (
16).

On the other hand, a positive photoresist, for example, is applied to the concave surface (12) of the material of the bearing part (11), and this is applied to the axis (A
Attach it to the holder (19) so that > matches the shaft (8). Further, the position of the moving table (18) is adjusted so that the axis (A) of the receiving part (11) and the height of the light @ (C) match.

In this state, the tip of the support rod (24) is attached to the receiving part (1).
1), the optical axis (C) intersects the photoresist surface of the concave surface (12) at a right angle at one point P. Hereinafter, this point P will be referred to as the irradiation point.

Then, the laser beam is irradiated onto the irradiation point P only while the shutter of the laser device (23) is open.

With the moving table (18) stopped, move the holder (19) to 1.
By rotating, the irradiation point P moves on one circle. By opening the shutter as appropriate during this time, it is possible to irradiate and expose an arbitrary range on this circle with laser light. By repeating this operation while changing the position X little by little, 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 briefly explained in detail below.

First, move the moving table (18
) is stopped, and the rotation of the holder (19) is stopped at the origin so that the rotation angle φ becomes O. Control device (1
9) is based on the pattern 14 (13) found earlier, x
The range of φ corresponding to the grooves (G1) to (G10) when =x1 is determined in advance. Then, the holder (19) is rotated once, and the laser device (23) is rotated only while φ is in the range corresponding to the groove (G1) to <G10).
Open one ivy. As a result, the groove (G1) on the circle R1 ~
Only the portion (G10) is irradiated with laser light and exposed. Once the holder (19) has rotated once, move the moving base (18) so that the position x becomes a little larger and stop!
After determining the range of φ corresponding to the X cutting grooves (G1) to (G10), the holder (19) is rotated once while controlling the shutter in the same manner as described above. Thereafter, the same operation is repeated while changing the position X by the same amount until X becomes x3. As a result, the groove (G1) in Fig. 3
~(GIO) are all exposed.

By moving the moving table (18) in the axis (X) direction at an appropriate speed and simultaneously rotating the holder (19) at an appropriate speed, the irradiation point P can be moved along any straight line or curve in Fig. 3. It can be moved by At this time, by moving the irradiation point P along the above straight line or curve with the shutter of the laser device (23) open, all points on it can be irradiated and exposed with 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 moving table (18) and the holder (19) are stopped and moved so that the irradiation point P is located at Pl of the first groove (G1) in FIG. Then, with the shutter of the laser device @ (23) open, the irradiation point P passes from Pl to P3.
The moving table (18) is moved and the holder (19) is rotated at the same time so that the moving table (18) is moved along the straight line T1 bent at Pl until it reaches Pl. As a result, all points on the direct FilTI are irradiated with laser light and exposed. Next, move the moving table (18) and rotate the holder (19) at the same time so that the irradiation point P moves in the opposite direction on a straight line parallel to T1 with X slightly larger than T1. Expose all points. Repeat this action,
Finally, all points on the first groove (G1) are exposed by simultaneously moving the moving table (18) and rotating the holder (19) so that the irradiation point P moves along the straight line T2. .

Then, by repeating the same operation for the remaining grooves (G2) to (G10), all the grooves (G10) in FIG.
G1) to (G10) can be exposed. The above straight lines T1 to T2 can be automatically determined by the control device (11) from the pattern of the grooves (13). In the case of the pattern of the grooves (15) as shown in Fig. 3, by keeping the ratio of the moving speed of the moving table (19) and the rotating speed of the holder (19) constant, the irradiation point P can be moved along the straight line T1 to T2. can be moved.

Of course, the above-mentioned device can also be used for machining grooves on concave surfaces other than the receiving portion of journal hydrodynamic bearings.

FIG. 4 shows a hydrodynamic bearing different from that in FIG. 2.

This rice barley consists of an upright shaft part (28) with a conical part formed at the lower end, and a receiving part (30) having a conical concave surface (29) for receiving this part. A plurality of shallow spiral grooves (31) are formed at equal intervals on the surface.

The groove (31) of the receiving portion (30) of the bearing shown in FIG. 4 can be processed by a method similar to the first and second methods described above, as shown in FIG. In this case, the optical axis (
The tips of the support rod (24) and the optical fiber (25) are bent in the horizontal plane so that C) intersects the concave surface (29) of the receiving part (30) at right angles. As is clear from FIG. 5, simply moving the receiving part (30) in the axis (X) direction changes the distance between the lens (26) at the tip of the optical fiber (25) and the irradiation point P. Therefore, when moving the moving table (18) in the axis (X) direction, it is also moved in the axis (Y) direction so that the above-mentioned interval is always constant. Further, the diameter of the concave surface (29) of the receiving portion (30) changes depending on the position X. Therefore, when using a method similar to the first method, if the rotational speed of the holder (19) is constant even if the position WX changes, the irradiation point P
The circumferential speed changes depending on X, and the exposure time becomes shorter in areas where the circumferential speed is large. Therefore, even if the position X changes, it is desirable to change the rotational speed as X changes so that the exposure time at each point is the same, that is, the peripheral speed is the same.

FIG. 6 shows a spherical hydrodynamic bearing. This bearing is upright @
It consists of a shaft part (34) with a sphere (33) integrally formed at the lower end of the (32), and a receiving part (36) having a hemispherical concave surface (35) for receiving the lower half of the sphere (33). . Receiving part (3
6) (7) The axis (A) passes through the center (o) of the concave surface (35), and a plurality of shallow spiral grooves (37) are provided at equal intervals on the concave surface (35) of the receiving part (36). It is being

The groove (37) in the receiving portion (36) of the bearing shown in FIG. 6 can be processed by a method similar to that shown in FIG. 4, as shown in FIG.

FIG. 8 shows the main parts of a groove machining device for machining the groove (37) of the bearing part (36) of the bearing shown in FIG. 6 by another method,
A disc-shaped rotary table (
38) is mounted so as to be rotatable about a vertical axis (Z), and a holder (19) is mounted on this table (38). The holder (19) is preferably movable relative to the table (38) in a direction parallel to its central axis of rotation (B). Furthermore, the tips of the support rod (24) and the optical fiber (25) are approximately 45mm wide in the horizontal plane.
bent to °. Others are the same as those in Figure 1,
The same parts are given the same reference numerals.

The groove (37) of the bearing part (36) of the bearing shown in FIG.
), the concave surface (35) of the material of the receiving part (36)
For example, a positive photoresist is applied to the holder (19), and the holder (19) is mounted so that the axis (A) coincides with the axis (B). Also, the center (0) of the concave surface (35) is the axis (Z)
Adjust the position of the receiving part (36) so that it is on top. Further, the table (38 ).

The pattern of the grooves (37) in the receiving part (36) of the bearing in Fig. 6 is as shown in Fig. 9, with a rotation angle θ around the axis (Z) and a rotation angle φ around the axis (<8). can be expressed. Therefore, as in the case of the apparatus shown in FIG.
By combining the rotation of step 8), the rotation of the holder (19), and the opening and opening of the vine of the laser device (23), the groove (G) can be exposed.

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.

The grooving device according to the present invention can be applied to grooving not only concave surfaces as described above but also convex surfaces such as the surface of a shaft portion or the surface of a spherical body.

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 photomask as in the conventional method, and therefore the number of steps is reduced, and there is no fear that the photoresist film will peel off due to the photomask. In addition, the irradiation device is equipped with an optical fiber fixed to a cantilevered support rod, and the laser beam is irradiated from the tip of the optical fiber. Accurate grooves can be easily machined even on concave surfaces such as the inner surface of.

[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 sectional view showing a grooved receiving part of a journal dynamic pressure bearing, and Fig. 3 is a groove in the shaft part of Fig. 2. Fig. 4 is a vertical cross-sectional view showing the grooved receiving part of the hydrodynamic bearing, which is different from Fig. 2, and Fig. 5 is the state when machining the groove of the receiving part in Fig. 4. Figure 6 is a plan view of the main part of the groove machining device; Figure 6 is a vertical sectional view showing the grooved receiving part of the spherical hydrodynamic bearing;
Figure 5 shows the condition when machining the groove of the receiving part in Figure 6.
Figure 8 is a plan view showing the main part of a groove machining device for machining the receiver shown in Figure 6 using a different method, and Figure 9 shows the groove pattern of the receiver shown in Figure 6. It is a diagram shown in pitch type coordinates. (11)... Receiving part, (12)... Concave surface, (13)...
...Groove, (15)...Workpiece drive device, (16)...
・Irradiation device, (17)...control device, (29)...
Concave surface, (30)...Receptacle, (31)...Groove, (35
)...concave surface, (36)...receptacle, (37)...groove. Patent 1 applicant: Koyo Seiko Co., Ltd. Figure 17

Claims (1)

[Claims] It is equipped with an irradiation device for irradiating laser light onto the photoresist coated on the surface of the workpiece. A groove machining device for dynamic pressure bearings that is designed to be irradiated with laser light.