JPH0811834B2 - 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 peel off when the film mask is covered or removed.

Further, particularly in the case of a journal dynamic pressure bearing in which the shaft portion is supported by the cylindrical receiving portion, there are many advantages if the inner surface of the receiving portion can be grooved. For example, positioning of the shaft portion and the receiving portion becomes easier as compared with the case where grooves are formed on the outer periphery of the shaft portion. Moreover,
Since the bearing is formed only by attaching the receiving portion to the housing, the same handling as the conventional rolling bearing can be performed.
However, it is very difficult to process the groove on the inner surface of the cylinder by the photo-etching method, and therefore, conventionally, the groove is usually processed on the surface of the shaft portion. As a method of processing a groove on the inner surface of a cylinder, there is known a method of machining such as inner diameter machining and plastic working. However, such machining has a problem in accuracy, and is not suitable for groove processing of a dynamic pressure bearing in which groove accuracy directly affects bearing performance.

An object of the present invention is to solve all of the above problems, and to provide a groove processing device for a dynamic pressure bearing, which can easily form a groove with high precision even on a concave surface such as an inner surface of a cylinder.

Means for Solving the Problems The apparatus according to the present invention comprises an irradiation device for irradiating a photoresist applied on the surface of a workpiece with a laser beam, and the irradiation device is used for a cantilevered support rod. A fixed optical fiber is provided, and laser light is emitted from the tip of this optical fiber.

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

The bearing shown in FIG. 2 comprises a shaft portion (10) and a cylindrical receiving portion (11) for receiving the shaft portion (10), and the inner surface (concave surface) (1) of the receiving portion (11) (1
2) A plurality of shallow double spiral (herringbone) grooves (13) are formed at equal intervals. Then, the rotation of the shaft (10) pumps the groove (13) to generate a dynamic pressure in the fluid (lubricant) so that the shaft (10) is supported on the concave surface (12) in a non-contact manner. There is. In FIG. 2, A represents the axis of the receiving portion (11). Also, X represents the position in the direction of the axis (A), and the position of one end of the groove (13) is x.
The position of the other end is represented by x3, and the position of the bending point is represented by x2. Then, R1 is a circle connecting the points of x = x1 on the concave surface (12) of the receiving portion (11), R2 is a circle connecting the points of x = x2, and R3 is a circle connecting the points of x = x3.

The point on the concave surface (12) of the receiving part (11) is the receiving part (11).
Is represented by a position x in the direction of the axis (A) and a rotation angle φ about the axis (A). And the groove (13) on the concave surface (12)
When the pattern is represented by the position x and the rotation angle φ, it becomes as shown in FIG. In the figure, (G1) to (G10) are grooves (13)
The portions (grooves), (H1) to (H10) represent the portions (hills) of the hill (14) between the grooves (13). Further, α is the spiral angle of the groove (13). In this type of bearing,
Generally, the ratio of the width of the hill (14) to the width of the groove (13) (hill / groove ratio)
Is 1. Therefore, given the number of grooves (13), the spiral angle α, and the positions x1, x2 and x3, the groove pattern as shown in FIG. 3 is determined. Further, even if the hill / groove ratio is other than 1, if the hill / groove ratio is given in addition to the above, the groove pattern is determined. The circles R1, R2 and R3 in FIG. 2 are represented by straight lines L1, L2 and L3 in FIG. As is clear from FIG. 3, on the circle where the position x is between x1 and x3,
Grooves (G1) to (G10) and hills (H1) to (H10) are displayed alternately. When the position x changes, the groove (G1) ~
The range of rotation angle φ in which (G10) appears changes. However, there is a constant relationship between the position x and the range of the rotation angle φ at which the grooves (G1) to (G10) appear at that time, and once the pattern of the groove (13) is determined, the groove part is determined for each position x. (G1)
The range of the rotation angle φ corresponding to (G10) can be obtained.

Grooving equipment consists of the workpiece drive (15), irradiation equipment (1
6) and these control devices (17).

The workpiece driving device (15) includes a horizontal moving table (18) and a workpiece holder (19) mounted on the moving table (18) so as to be rotatable about a horizontal axis (B). ing. The moving table (18) is provided with a moving device (20) for moving the moving table (18) in the horizontal axis (X) direction parallel to the axis (B),
The moving device (20) is connected to the control device (17) via the interface (21). The holder (19) has a rotating device (22) for rotating the holder (19) around the shaft (B).
Is provided, and the rotating device (22) is also connected to the control device (17) via the interface (21). The movable table (18) is preferably movable in the vertical direction and in the horizontal axis (Y) direction orthogonal to the axis (X), and a moving device for this purpose is also connected to the control device (17).

The irradiation device (16) includes a laser device (23),
The laser device (23) is connected to the control device (17) via the interface (21). Laser device (2
The optical axis (C) of 3) is parallel to the axis (X), and a hollow support rod (24) extending in the axis (X) direction toward the workpiece driving device (15) at the tip of the laser device (23). Is cantilevered. 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 substantially right angle in a horizontal plane, and a spherical lens (26) for condensing the laser light that has passed through the optical fiber (25) is attached to the tip thereof. There is.

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

When machining the groove (13) of the bearing part (11) of the bearing shown in FIG. 2, first, in the control device (17), the number of grooves (15), the positions x1, x3 and x2 of both ends and the bending point, the spiral Enter the angle α as well as the hill / groove ratio. Then, the control device (17) determines the pattern of the groove (13) as shown in FIG. 3 from these information, and based on this, the workpiece drive device (15) as described later.
And controlling the irradiation device (16).

On the other hand, the concave surface (12) of the material of the bearing (11) of the bearing is coated with, for example, a hosi-shaped photoresist, and this is applied to the axis (A).
Attach it to the holder (19) so that is aligned with the axis (B).
Further, the position of the movable table (18) is adjusted so that the heights of the optical axis (C) and the axis (A) of the receiving portion (11) are aligned.

In this state, attach the tip of the support rod (24) to the receiving portion (1
When inserted inside 1), the optical axis (C) intersects the concave surface (12) of the photoresist surface at a right angle at a point P. Hereinafter, this point P is referred to as an irradiation point. Then, the irradiation point P is irradiated with laser light only while the shutter of the laser device (23) is open.

The irradiation point P moves on one circle by rotating the holder (19) once while the movable table (18) is stopped. By appropriately opening and closing the shutter during this time, it is possible to irradiate and expose the laser beam to an arbitrary range on this circle. Then, by repeating such an operation while changing the position x little by little, it is possible to irradiate and expose a desired range of the photoresist 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, move the moving table (18) so that the irradiation point P is at the x1 position.
And the rotation of the holder (19) is stopped at the origin so that the rotation angle φ becomes zero. Control equipment (19)
Is the range of φ corresponding to the groove portions (G1) to (G10) when x = x1 is obtained from the previously obtained pattern of the groove (13). Then, the holder (19) is rotated once, and the shutter of the laser device (23) is opened only while φ is in the range corresponding to the groove portions (G1) to (G10). As a result, only the groove portions (G1) to (G10) on the circle R1 are irradiated with the laser light and exposed. If the holder (19) has rotated once,
The movable table (18) is moved and stopped so that the position x becomes a little larger, and the range of φ corresponding to the groove portions (G1) to (G10) at this x is obtained. Rotate the holder (19) once while controlling. Hereinafter, while changing the position x by the same amount, the same operation is repeated until x becomes x3. As a result, the groove portion (G1) in FIG.
(G10) is all exposed.

By moving the movable table (18) in the direction of the axis (X) at an appropriate speed and simultaneously rotating the holder (19) at an appropriate speed, the irradiation point P can be moved along an arbitrary straight line or curve in FIG. Can be moved. At this time, by moving the irradiation point P along the straight line or the curved line with the shutter of the laser device (23) open, all 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 moving table (18) and the holder (19) are stopped so that the irradiation point P comes to P1 of the first groove (G1) in FIG. Then, while the shutter of the laser device (23) is open, the moving table (18) is moved so that the irradiation point P moves along the straight line T1 bent at P2 from P1 to P2 to P3. At the same time, rotate the holder (19). As a result, all points on the straight line T1 are irradiated with laser light and exposed. Next, the holder (19) is rotated at the same time as the moving table (18) is moved so that the irradiation point P moves in the opposite direction on a straight line in which X is slightly larger than T1 and is parallel to this line. Expose all points of. By repeating such operations, and finally by simultaneously moving the moving table (18) and rotating the holder (19) so that the irradiation point P moves along the straight line T2, the first groove portion (G1) is moved. All points are exposed. And the remaining grooves (G2) to (G10)
By repeating the same operation for, all the groove portions (G1) to (G10) in FIG. 3 can be exposed. The straight lines T1 and T2 can be automatically obtained by the control device (17) from the pattern of the groove (13). In the case of the pattern of the groove (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 along the straight lines T1 to T2. Can be moved.

The above-mentioned device can of course be used for machining concave grooves other than the receiving portion of the journal dynamic pressure bearing.

FIG. 4 shows a dynamic pressure bearing different from that of FIG. This bearing has an upright shaft part (28) with a conical part formed at the lower end.
And a receiving portion (30) having a conical concave surface (29) for receiving this portion, and a plurality of shallow spiral grooves (31) are formed at equal intervals on the surface of the concave surface (29).

The groove (31) of the bearing part (30) of the bearing shown in FIG.
As shown in the figure, the same method as the first and second methods described above can be used. In this case, the tip ends of the support rod (24) and the optical fiber (25) are bent in a horizontal plane so that the optical axis (C) intersects the concave surface (29) of the receiving portion (30) at a right angle. . As is clear from FIG. 5, the distance between the lens (26) at the tip of the optical fiber (25) and the irradiation point P is changed only by moving the receiving portion (30) in the axis (X) direction. For this reason, when the movable table (18) is moved in the axis (X) direction, it is also moved in the axis (Y) direction so that the interval is always constant.
The diameter of the concave surface (29) of the receiving portion (30) changes depending on the position x. Therefore, in the case of the same method as the first method described above, if the rotation speed of the holder (19) is constant even if the position x changes, the peripheral speed of the irradiation point P changes according to x, and the peripheral speed of the irradiation point P changes. The exposure time becomes shorter as the speed increases. Therefore, even if the position x changes, it is desirable to change the rotation speed in accordance with the change in x so that the exposure time at each point becomes equal, that is, the peripheral speed becomes equal.

FIG. 6 shows a spherical dynamic pressure bearing. This bearing has a shaft (3) in which a spherical body (33) is integrally formed at the lower end of the upright shaft (32).
4) and a hemispherical concave surface (3) that receives the lower half of the sphere (33).
And a receiving part (36) having 5). The axis (A) of the receiving portion (36) passes through the center (O) of the concave surface (35), and a plurality of shallow spiral grooves (3) are formed in the concave surface (35) of the receiving portion (36).
7) are provided at equal intervals.

The groove (37) of the bearing part (36) of the bearing shown in FIG.
As shown in the figure, it can be carried out in the same manner as in FIG.

FIG. 8 shows a main part of a groove processing device for processing the groove (37) of the bearing portion (36) of the bearing shown in FIG. 6 by another method, and is shown on the moving table (18) of FIG. Disk-shaped rotary table (38)
Is mounted so that it can rotate about the vertical axis (Z),
The holder (19) is mounted on the table (38). The holder (19) is preferably movable with respect to the table (38) in a direction parallel to the central axis of rotation (B) thereof. The tip ends of the support rod (24) and the optical fiber (25) are bent at about 45 ° in the horizontal plane. Others are the same as those in FIG. 1, and the same components are denoted by the same reference numerals.

In the device of FIG. 8, the groove (37) of the bearing part (36) of the bearing of FIG.
In the case of processing, a positive type photoresist, for example, is applied to the concave surface (35) of the material of the receiving portion (36), and this is attached to the holder (19) so that the axis (A) and the axis (B) coincide with each other. . Further, the position of the receiving portion (36) is adjusted so that the center (O) of the concave surface (35) is on the axis (Z). Further, the heights of the axis (B) and the optical axis (C) are the same, and the optical axis (C) at the tip of the optical fiber (25) passes through the center (O) of the concave surface (35). ) Position.

The pattern of the groove (37) of the bearing part (36) of the bearing shown in FIG.
As shown in FIG. 9, it can be represented by a rotation angle θ around the axis (Z) and a rotation angle φ around the axis (B). Therefore, as in the case of the device of FIG. 1, the table (38)
Rotation, holder (19) rotation and laser equipment (23)
By combining the opening and closing of the shutter, the groove (G)
Can be exposed.

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

The groove processing apparatus according to the present invention can be applied to groove processing of a convex surface such as the surface of a shaft portion or the surface of a spherical body, in addition to the above concave surface.

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. Therefore, unlike the conventional case, it is not necessary to use a photomask, so that the number of steps is reduced, and there is no fear that the photoresist film is peeled off by the photomask. Further, since the irradiation device is provided with an optical fiber fixed to a cantilevered support rod, and laser light is emitted from the tip of this optical fiber, for example, a cylindrical receiving portion of a journal dynamic pressure bearing. It is possible to easily form a groove with high precision on a concave surface such as the inner surface of the.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a groove processing apparatus showing an embodiment of the present invention, FIG. 2 is a vertical sectional view showing a grooved receiving portion of a journal dynamic pressure bearing, and FIG. 3 is a groove of a shaft portion of FIG. Shows the pattern in columnar polar coordinates, FIG. 4 is a vertical sectional view showing a grooved receiving portion of a dynamic pressure bearing different from FIG. 2, and FIG. 5 is a state when processing the groove of the receiving portion of FIG. FIG. 7 is a plan view of the main part of the groove machining apparatus, FIG. 6 is a vertical sectional view showing the grooved receiving part of the spherical dynamic pressure bearing, FIG.
FIG. 5 is a view showing a state when the groove of the receiving portion of FIG. 6 is processed.
FIG. 8 is a plan view showing a main part of a groove processing apparatus for processing the receiving portion of FIG. 6 by another method, and FIG. 9 is a groove pattern of the receiving portion of FIG. It is a figure shown by a spherical polar coordinate. (11) …… Receiving part, (12) …… Concave, (13) …… Groove, (1
5) Workpiece drive, (16) …… Irradiator, (17)
...... Control device, (29) …… Concave surface, (30) …… Receiving part, (3
1) Groove, (35) …… Concave, (36) …… Receiving part, (37)
……groove.

Claims (1)

[Claims] 1. An irradiation device for irradiating a laser beam onto a photoresist applied to the surface of a workpiece,
A groove processing device for a dynamic pressure bearing, wherein the irradiation device comprises an optical fiber fixed to a cantilevered support rod, and laser light is emitted from the tip of the optical fiber.