JPH0674807B2 - Grooving method for ceramic dynamic bearings - Google Patents

Description

TECHNICAL FIELD The present invention relates to a groove processing method for a ceramic dynamic pressure bearing in which a dynamic pressure generating groove is formed on the surface of a ceramic dynamic pressure bearing substrate.

[Prior art]

Conventionally, the following method has been proposed as a groove processing method for a dynamic pressure generating groove of a ceramic dynamic pressure bearing. That is, a method of processing with a Nd: YAG (neodymium yttrium aluminum garnet) laser with a Q switch (hereinafter simply referred to as "YAGQ switch pulse laser"), and a method of using a YAGQ switch pulse laser and an assist gas together as an application example, A method of processing in processing liquid / vacuum.

[Problems to be Solved by the Invention]

YAGQ switch pulsed laser light has many advantages such as high peak output, excellent workability, and excellent stability and reliability.However, when the workpiece is a dynamic pressure bearing, There was such a problem.

(1) As the laser irradiation time elapses, heat is accumulated inside the workpiece, the heat-affected layer increases, and as shown in FIG. 3 (b), cracks 12 occur and molten solidified matter is deposited.
13 forming, different in the first and last aspects of processing.

(2) In order to remove the deposit 13 as in (1) above,
Rework is necessary, and rework is extremely difficult in radial bearings.

(3) As one of the means for preventing the problem of (1) above, there is a method of controlling the peak output and the pulse width, but it is difficult to change them at any time during processing.

(4) As another means for preventing the problem of the above (1), there is a method of using an assist gas together and processing in a working liquid / vacuum, but it is difficult to completely remove the deposited portion. In addition, it requires a special device and a chemical solution, which is troublesome.

The present invention has been made in view of the above points, and provides a groove processing method for a ceramic dynamic pressure bearing, which can easily and accurately form a dynamic pressure generation groove on a sliding surface of a ceramic dynamic pressure bearing base material. The purpose is to do.

[Means for Solving the Problems]

In order to solve the above problems, the present invention provides a groove processing method for a ceramic dynamic pressure bearing in which a predetermined groove is formed on a processed surface of a base material of a ceramic dynamic pressure bearing, in which a pulse laser beam from a YAGQ switching pulse laser device is used. The low-intensity beam portion around the periphery is cut off, the high-energy beam in the center is extracted, and the beam diameter at this time is selected to be the spot diameter of the laser beam. First, the portion corresponding to the outer contour portion of the groove on the processed surface of the base material is irradiated to form the outer contour portion of the groove, and thereafter, the pulse laser light is irradiated inside the outer contour portion to form the groove. It is characterized by

[Action]

According to the present invention, by adopting the above-mentioned configuration in the groove processing method for the ceramic dynamic pressure bearing, the laser beam from the YAGQ switching pulse laser device has a high energy intensity at the central portion, and blocks the low energy intensity portion at the peripheral portion. However, since only the central portion with high energy intensity is taken out and the beam diameter at this time is selected to be the spot diameter of the laser beam, the laser beam can accurately and efficiently process grooves. Become a beam. When the outer contour of the starting groove is formed using this laser beam, the outer contour is formed in substantially the same way as the groove formed when one line is formed by one beam scanning of the laser light, and therefore the edge portion of the groove is formed. No volume is formed at. Therefore, it is possible to accurately and efficiently form the predetermined groove on the processed surface of the base material of the ceramic dynamic pressure bearing.

〔Example〕

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

FIG. 2 is a plan view showing an example of a ceramic dynamic pressure bearing. As shown in the drawing, the processing method of the present invention will be described by taking as an example the case where a groove 10a for generating a dynamic pressure is formed on a substrate 10 made of a ceramic disk.

As shown in FIG. 1, this processing method irradiates a portion of the processing surface of the base material 10 corresponding to the outer contour portion of the groove 10a with the YAGQ switch pulse laser beam to form the outer contour portion of the groove 10a. After that, the inside of the outer contour portion is irradiated with pulsed laser light to form the groove 10a. In the figure, 10b indicates the outer diameter of the base material 10 and 10c indicates the inner diameter.

By processing as described above, as will be described in detail later, the contour of the groove 10a becomes the same as that removed when one line is formed by one beam scanning, and a deposited portion is not formed, Since the contours can be connected by a straight line or a curved line, the contour shape can be accurately formed. Further, by removing the inside after forming the contoured portion, the melted and solidified material is confined inside the groove 10a, so that the melted and solidified material adheres to the outside of the groove 10a, and a deposited portion is not formed. Hereinafter, the above processing method will be described in detail.

FIG. 3 is a cross-sectional view of a groove processed when ceramics are removed by using a YAGQ switch pulsed laser beam, and FIG. 3 (a) shows a case where one line is formed by one beam scanning of the pulsed laser beam. 2B is a sectional shape when the pulsed laser light is scanned along the locus 11.

When one line is formed by one-time beam scanning with the pulsed laser light, the laser light is absorbed by the surface of the ceramic material that is the workpiece 9 and converted into thermal energy as shown in FIG. 3 (a). As a result, the temperature of the processed portion rises. As a result, the ceramic material in that portion is melted, evaporated and removed to form the groove 15. At this time, when one line is formed by scanning the laser beam once, as shown in FIG. 1 (a), the deposit 13 of the molten solidified material 9a is not formed. On the other hand, as shown in FIG.
When the YAGQ switch pulsed laser beam is scanned by 11, the side wall of the initial S portion of the irradiation is deep and steep, but as the irradiation is repeated, the generated melt or evaporate solidifies immediately and becomes a molten coagulated product 9a. Since the laser light is scattered and deposited on the next processed surface, the laser light is absorbed or reflected by the laser light, and the groove 15 becomes gradually shallow. In addition, heat is accumulated inside the workpiece ceramic, and the heat-affected layer increases. As a result, the groove depth varies and the melted and solidified layer is thick, and the deposit 13 is formed at the processing end point E. Also, the cracks 12 are likely to be formed. When the cracks 12 are generated, the melted and solidified material 9a is peeled off during use of the bearing and enters the bearing sliding surface, causing trouble.

Therefore, when forming the groove 10a shown in FIG. 2, when the laser beam is scanned as shown by L in FIG. 4 (a), the portion B in the figure becomes jagged and the portion B is closed. Since it is a portion, a deposit of molten solidified material is formed. Further, as shown by L in FIG. 4 (b), when the laser beam is scanned, the number of times of scanning becomes particularly large, so that the portions A and B are notched, and the processing accuracy is significantly reduced.

Therefore, when forming the groove 10a in the base material 10 as shown in FIG. 1, if the outer contour of the groove 10a is formed first,
The formation of the outer contour is substantially the same as the groove formed when one line is formed by one beam scanning of the laser light as shown in FIG. 3 (a), so that no deposition portion is formed at the edge of the groove. .

Next, the YAGQ switch pulsed laser light used in the processing method of the present invention will be described. FIG. 5 is a diagram showing a beam intensity distribution of a general YAGQ switch pulsed laser beam. As shown in the drawing, the laser beam has an energy distribution in which the central portion is strong and the peripheral portion is weak. That is, the normal distribution has a strong energy intensity in the central portion. A laser beam having such an intensity distribution is cut off by using an aperture or the like to weaken the laser beam having a weak intensity in the peripheral portion, and only the laser beam having a strong intensity in the central portion is taken out. Select to be the spot diameter.
Here, the beam spot diameter is the maximum intensity of the beam, I, and the beam radius of the intensity of I / e ² is r _1, and the beam in the range of −r ₁ to + r ₁ (d = 220 μm) Refers to the diameter. The grooved shape can be processed more accurately and efficiently by processing with the laser beam of the central portion having high energy density. FIG. 6 is a diagram showing a schematic configuration of the laser processing apparatus. The ceramic base material 22 is placed on the XY moving table 21, and the output pulse laser light from the laser oscillator 25 composed of the YAGQ switch pulse laser oscillator is the aperture 5 and the peripheral laser beam is shown in FIG. After being cut as shown in, only the laser beam with high energy density in the center is reflected by the total reflection mirror 24,
The light is condensed by the condenser lens 23 and is irradiated onto the processed surface of the base material 22. In this state, drive the XY moving table 21, align the processing position of the base material 22 with the irradiation position of the laser light,
The laser oscillator 25 is driven to irradiate the base material 22 with the short pulse laser light generated by the YAGQ switch pulse laser oscillation.
The movement of the laser beam is performed along the outer diameter contour of the groove 10a as shown in FIG. 1, and then zigzag scanning is performed inside the outer diameter contour. By repeating such a removing process, the depth of the ceramic substrate 10 is 3 to 20 μm and the ratio of the depth to the width d /
Form a groove 10a such that w = 10 ⁻⁴ to 10 ⁻² .

In this embodiment, SiC is used as the ceramic material of the base 10 and Y
The repetition rate of the AGQ switch laser was 0.32 kHz and the XY table moving speed was 5 m / sec.

In the above embodiment, the laser beam scanning is
Although the example using the YX moving table 21 is shown, the scanning method of the laser beam is not limited to this, and a galvanometer type optical scanner method of transmitting and scanning the laser beam by a galvanometer mirror, or an optical fiber for guiding the laser beam. Any of the optical fiber methods for scanning the tip may be used.

Further, although the processing method of the present invention can be realized in general ceramics, SiC, Si ₂ N ₄ , Al which is frequently used as a bearing is particularly used.
₂ O ³ etc. are effective.

Further, in the processing method of the present invention, the shape of the object to be processed, that is, the shape of the base material of the dynamic pressure bearing, the shape of the processing groove, etc. does not matter.

By grooving ceramic dynamic bearings as described above, once the laser processing conditions are set, a large amount of ceramic dynamic bearings can be produced under the same conditions, and the automation of the machining process can be easily performed. Comes out.

Further, since the pretreatment process such as masking is not required, the washing process required for the pretreatment is also unnecessary.

The energy source is the excitation light lamp of the YAGQ switch pulsed laser, and since this lamp has a long life and is inexpensive, maintenance is simple and running costs are low.

〔The invention's effect〕

As described above, according to the present invention, the low-intensity beam portion around the pulse laser beam from the YAGQ switching pulse laser device is blocked, the beam with high energy intensity in the central portion is extracted, and the beam diameter at this time is further reduced. Is selected to be the spot diameter of the laser beam, and the laser beam light having the high energy density is first irradiated to the portion corresponding to the outer contour portion of the groove on the processed surface of the base material to form the outer contour portion of the groove. However, after that, since the inside of the outer contour portion is irradiated with the pulsed laser light, the following excellent effects can be obtained.

(1) Since it is possible to prevent the melted and solidified material from adhering to other than the groove portion, it is possible to perform highly accurate and highly reliable processing without requiring final finishing.

(2) Once the processing conditions are set, a large amount of the same size,
It is possible to obtain high quality products with accuracy.

(3) As compared with mechanical processing such as shot blasting, generation of cracks after processing can be suppressed, and generation of particles, which is a serious problem in use, can be eliminated.

(4) A stable and highly reliable processing method is used because it uses stable and stable YAGQ switch pulsed laser light.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a method of processing a ceramic dynamic pressure bearing of the present invention, FIG. 2 is a diagram showing an example of a ceramic dynamic pressure bearing, FIG. 3 (a). (B) is a view showing a cross-sectional shape of a processed groove when ceramics are removed by using a laser beam, and FIGS. 4 (a) and 4 (b) are views showing a groove processing method other than the present invention, respectively. FIG. 5 is a diagram showing the energy distribution of a general YAGQ switch pulse laser beam, and FIG. 6 is a diagram showing a schematic configuration of a laser processing apparatus. In the figure, 9 ... Base surface of ceramic dynamic pressure bearing, 9a ...
… Melt / solidification layer, 10 …… Ceramics dynamic pressure bearing substrate, 11 …… YAGQ switch Pulse laser beam trajectory, 12 ……
Microcrack, 13 ... Accumulation part.

Front page continued (72) Inventor Togaku Manabu 11-1 Haneda Asahi-cho, Ota-ku, Tokyo Inside the EBARA CORPORATION (72) Inventor Yoshio Sato 11-11 Haneda-Asahi-cho, Ota-ku, Tokyo Inside the EBARA CORPORATION (56) References JP-A-1-247566 (JP, A) JP-A-57-132909 (JP, A)

Claims (1)

[Claims] 1. A method for grooving a ceramic dynamic pressure bearing in which a predetermined groove is formed on a processed surface of a base material of a ceramic dynamic pressure bearing, wherein a low intensity around a pulse laser beam from a YAGQ switching pulse laser device is provided. The beam portion is cut off, the beam with high energy intensity in the central portion is extracted, and the beam diameter at this time is selected to be the spot diameter of the laser beam. The portion corresponding to the outer contour portion of the groove on the machined surface is irradiated to form the outer contour portion of the groove, and thereafter, the pulse laser beam is irradiated to the inside of the outer contour portion to form the groove. A groove machining method for a ceramic dynamic pressure bearing, comprising: