JPH03146284A - Production of dynamic fluid bearing - Google Patents

Abstract

PURPOSE:To form a dynamic pressure generating groove of a good yield in a short period of time by holding a fixing shaft freely rotatably to a moving table and irradiating the outer peripheral surface of a shaft rotating with a laser beam while moving the moving table in an axial direction. CONSTITUTION:The fixing shaft 3a rotates in an arrow (b) direction while linearly moving in an arrow (a) direction and, therefore, the spiral dynamic pressure-generating groove is formed on the outer peripheral surface thereof. The working of the dynamic pressure-generating groove of the good yield in a short period of time is, therefore, possible. The easy dealing is thus executed even if the design of the dynamic pressure generating groove and the fixing shaft 3a is changed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a hydrodynamic bearing applied to an air-magnetic bearing type optical deflector, etc., and is particularly characterized by a method for processing a hydrodynamic groove. Regarding the manufacturing method.

[Conventional technology]

The following methods are conventionally known as methods for machining dynamic pressure generating grooves in hydrodynamic bearings used in polygon scanners and the like.

(1) Method by etching (2) Method by sandblasting (3) Method by plating (4) Method by rolling Are known.

[Problem to be solved by the invention]

Among the above conventional techniques, method (11) involves applying a photoresist, exposing it to patterning using a photomask, and etching it with a corrosive solution.This method requires a large number of steps, but Patterning exposure takes a considerable amount of time.Furthermore, if the applied photoresist is scratched, that part will also be etched, making the cost per hydrodynamic bearing extremely high and reducing yield. bad.

In method (2), grooves are formed by spraying fine abrasive grains instead of the corrosive liquid in method (1).

This method also has the same drawbacks as (1), so it is expensive,
This results in low yield.

Method (3) is to attach a mask in the shape of dynamic pressure generating grooves to the fixed shaft or rotating shaft, and then plate the unmasked areas or paste a thin film with the shape of dynamic pressure generating grooves. be. However, in the case of plating, since the amount of plating varies depending on the position, the roundness of the fixed shaft or rotating shaft deteriorates. In hydrodynamic bearings, roundness,
Because cylindricity must be controlled at submicron levels,
This problem is fatal.

Method (4) is to form a convex dynamic pressure generating groove on a roller or the like and press it against the roller to form the dynamic pressure generating groove. This method is suitable for mass production, but if a hard roller is pressed against it, there is a high possibility that the fixed shaft or rotating shaft will be distorted and the roundness and cylindricity will deteriorate. Further, when rolling is performed, microcracks are formed at the peripheral edge of the completed dynamic pressure generating groove. There is a great risk that the hydrodynamic bearing will seize due to the small pieces that have broken down from this crack.

As described above, each of the conventionally known manufacturing methods for hydrodynamic bearings has drawbacks.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a hydrodynamic bearing that can form hydrodynamic grooves in a hydrodynamic bearing in a short period of time with high yield and at low cost.

[Means to solve the problem]

The above purpose is to irradiate a laser beam onto the outer peripheral surface of the rotating fixed shaft or the inner peripheral receiving surface of the rotating shaft while rotatably holding the fixed shaft or rotating shaft on a moving table and moving the moving table in the axial direction. This is achieved by forming dynamic pressure generating grooves.

[Effect]

Since the fixed shaft or rotating shaft is rotated and moved in the axial direction on the movable table, the dynamic pressure is reduced by the laser beam irradiated to the appropriate position on the outer peripheral surface of the fixed shaft or the inner peripheral receiving surface of the rotating shaft. Grooves can be formed in a short time with good yield and at low cost.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a conceptual diagram of the entire hydrodynamic bearing manufacturing apparatus according to the present invention, in which 1 is a moving table linearly moved in the direction of arrow a by a motor 2, 3 is a workpiece held by a shaft 4, and 5 A motor 6a rotates the workpiece 3 and the shaft 4 integrally in the direction indicated by the arrow.

6b is an encoder signal line, 7 is a table controller, 8 is a control unit, 9 is a power unit (Q switch driver), 10 is a CO2 laser oscillator, 11a and llb are mirrors, 12 is a slit, and 13 is an objective lens for processing. Further, I4 is a laser beam.

Briefly explaining its operation, when processing data for the workpiece 3 is output from the control unit 8, the power unit 9 is operated by this output, which causes the COt laser oscillator lO to oscillate and emit the laser beam 14. do. Laser beam 1
4 is reflected by the mirrors 11a and 11b, and the slit 12
The beam shape is adjusted at , and the beam is incident on the objective lens 13 . This laser beam 14 is transmitted through the objective lens 13.
The beam is focused onto the workpiece 3 as a beam spot.

The workpiece 3 is moved by the movable table 1 in its axial direction (arrow a
direction) and rotated by the shaft 4 in the direction indicated by the arrow, for example, a spiral groove is formed on the outer peripheral surface of the workpiece 3 by irradiation of the beam spot at a fixed position. That will happen. The linear movement control of the moving table 1 and the rotation control of the shaft 4 are performed by inputting encoder signals from the encoder signal lines 6a and 5b to the control unit 8 via the table controller 7, where the reference value and the encoder signal are compared. , the results are output from the control section 8 to the table controller 7, and further output to each motor 2.
This is done by feeding back to 5.

Next, the specific details of the method for manufacturing a hydrodynamic bearing will be explained.

FIG. 1 is a conceptual diagram of a method for manufacturing a fixed shaft, and the COt laser oscillator 10 shown in FIG. 3 is a COt laser oscillator 10.

Sealed tube 10a, discharge electrode 10b, loc, Q switch 1
0d, a total reflection mirror 10e, and an output mirror 10f.

The workpiece 3 in this embodiment is a fixed shaft 3a, and the beam spot is irradiated at the same position as the normal to the outer peripheral surface of the fixed shaft 3a.

Since the fixed shaft 3a rotates in the direction indicated by the arrow a while moving linearly in the direction indicated by the arrow a, a spiral dynamic pressure generating groove 15 is formed on its outer peripheral surface.

FIG. 2 is a conceptual diagram of the manufacturing method of the rotating shaft, and shows the rotating shaft 3.
In the case of b, in order to irradiate the beam spot at the same position as the normal line of the inner peripheral receiving surface, mirrors 11a, 1l
The positional relationship between b, 11 C and the objective lens 13 is only slightly different from that in FIG. 1, and the rest is exactly the same as in the embodiment shown in FIG.

In this embodiment, a spiral dynamic pressure generating groove 15 is formed on the inner circumferential receiving surface of the rotating shaft 3b.

The laser device used in the present invention is preferably a CO□ laser, which is currently widely used in metal processing and the like, because it is relatively inexpensive and can obtain a large output.The CO2 laser is used with Q-switch oscillation pulses.

This is because the Q-switch oscillation pulse laser can more easily control the amount of heat provided than the continuous wave laser, so the amount of heat stored in the workpiece 3 can be reduced and thermal damage can be minimized. Furthermore, the oscillation of the Q switch 10d is
Encoders are attached to the motors 2 and 5 that rotate and linearly move the fixed shaft 3a or the rotary shaft 3b, and the encoders are synchronized with the signals of the motors 2 and 5. In this way, compared to synchronizing with the pulse signal that the motor 2.5 receives, the motor 2.5 actually rotates after the pulse signal is input, and the rotation speed reaches the predetermined rotation speed. Since delay time can be taken into account,
Misalignment of the dynamic pressure generating grooves 15 to be formed can be reduced.

Note that when the dynamic pressure generating grooves 15 are formed using a laser, the peripheral edges of the dynamic pressure generating grooves 15 are formed with a ridge or a bulge, albeit slightly. Therefore, the fixed shaft 3a after the formation of the dynamic pressure generating groove 15
Alternatively, the rotating shaft 3b is subjected to a finishing process such as cylindrical grinding to remove burrs and bulges.

The above-mentioned processing method makes it possible to process hydrodynamic grooves for fluid dynamic pressure bearings (fixed shaft 3a, rotary shaft 3b) in a short time and with high yield. In addition, with this processing method, even if the shape of the dynamic pressure generating groove 15 or the fluid dynamic pressure bearing is changed, it can be handled immediately by simply changing the program. There is no need to create a new one. Furthermore, multiple types of fluid dynamic pressure bearings can be manufactured on one line.

〔Effect of the invention〕

As explained above, according to the present invention, since the dynamic pressure generating grooves are formed using a laser, it is possible to process the dynamic pressure generating grooves with a high yield in a short time. It is possible to provide a method for manufacturing a hydrodynamic bearing that can easily cope with changes in the design of the rotating shaft.

[Brief explanation of the drawing]

1 and 2 are conceptual diagrams of a method for manufacturing a hydrodynamic bearing according to the present invention, and FIG. 3 is a conceptual diagram of an entire apparatus for manufacturing a hydrodynamic bearing. 1... Moving table, 3... Workpiece, 3a...
Fixed axis, 3b... Rotating axis, 4... Axis, 14... Laser beam, 15... Dynamic pressure generating groove. Figure 1 Figure 3 Figure 2 Procedural amendment (voluntary) Heisei

Claims (2)

[Claims] (1) The fixed shaft is rotatably held on a movable table, and while the movable table is moved in the axial direction, the outer peripheral surface of the rotating fixed shaft is irradiated with a laser beam to form dynamic pressure generating grooves. A manufacturing method for hydrodynamic bearings. (2) Dynamic pressure generating grooves are formed by holding the rotary shaft rotatably on a movable table and moving the movable table in the axial direction while irradiating a laser beam onto the inner circumferential receiving surface of the rotating rotary shaft. A method of manufacturing a hydrodynamic bearing, characterized in that: