JPH0313951B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for machining grooves on a shaft for a hydrodynamic bearing using a laser beam.

Conventionally, methods for forming grooves for generating dynamic pressure on the outer surface of a rotating shaft for hydrodynamic bearings include photo etching,
Alternatively, a method of machining the groove by electric discharge machining is used. However, all of these processing methods require long processing times and are difficult to mass-produce.
Therefore, the resulting bearings have been extremely expensive. When machining grooves by photo etching, the concentration and deterioration of the etching liquid, temperature, processing time, etc. are indirectly controlled, so the groove depth tends to vary and it is difficult to stabilize the quality of the bearing. It was hot. Also,
When a material such as stainless steel with good corrosion resistance is used for the rotating shaft, etching is extremely difficult, and there are problems with both quality and mass production in terms of ensuring groove accuracy and processing efficiency. Furthermore, using ceramic, which has excellent corrosion resistance, for the rotating shaft material had drawbacks such as the inability to process it.

On the other hand, when machining grooves by electric discharge machining,
It is extremely difficult to process complex groove patterns, and furthermore, new electrodes must be created each time to match the groove pattern, making it difficult to respond to design changes.Machining takes a long time and is difficult to mass-produce. There were disadvantages such as being inferior and being unable to process some materials.

This invention was made in order to eliminate the above-mentioned drawbacks.The shaft is made of corrosion-resistant stainless steel suitable for hydrodynamic bearings, and the complicated groove pattern for generating hydrodynamic pressure can be formed with precision. An object of the present invention is to provide a method for machining grooves on a shaft for a hydrodynamic bearing, which is easy to handle even when there is a change in pattern design, and is excellent in mass production.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a completed shaft for a hydrodynamic bearing, where 1 is a stainless steel shaft, and 2 and 3 are grooves for generating dynamic pressure formed on the outer peripheral surface of the shaft. FIG. 2 is an explanatory diagram for explaining the shaft groove machining method, in which 11 is a stainless steel shaft intermediate material pre-processed to the same or slightly larger dimensions than the finished shaft dimensions, 21 and 31 are These are grooves for generating dynamic pressure that are being formed on the outer surface of the intermediate material by irradiation with the laser beam 4.

These grooves for generating dynamic pressure connect the intermediate material 11 to
It is formed by irradiating the outer surface of the intermediate material 11 only at necessary locations while moving the laser beam in the axial direction of the shaft while rotating the intermediate material 11 intermittently about the shaft center. For this purpose, the irradiation position of the laser beam and the intermittent irradiation are controlled by a computer program created in advance. For example, in FIG. 2, on the narrow line I to I on the outer surface of the intermediate material 11, the laser beam starts from point C and starts from point D while moving the irradiation position in the direction of arrow A. Pulsed irradiation is performed continuously up to the point where the grooves are formed as shown in FIG. Irradiation is temporarily stopped at point D, pulsed irradiation is restarted at point E, continues until point F, and is interrupted at point F. Next, the point G is reached and pulsed irradiation is started again.
This irradiation continues until point H, is interrupted at point H, the interrupted state continues until point J, pulsed irradiation is started again at point J, and irradiation continues until point K.
At point K the irradiation is stopped.

Note that instead of changing the irradiation direction of the laser beam 4, the irradiation direction of the laser beam 4 may be fixed and moved in the axial direction by an XY table equipped with a rotation mechanism that rotationally drives the shaft intermediate material. Furthermore, the grooves can be formed by simultaneously controlling the rotation direction of the rotation mechanism and the X and Y directions of the XY table.

In this way, the position of laser beam irradiation and the intermittent irradiation are controlled by the computer program, and grooves are formed at necessary locations as shown in FIG.

While rotating the shaft intermediate material 11 intermittently as described above, the irradiation position of the laser beam is moved in the axial direction of the shaft and intermittent irradiation is applied to necessary locations on the outer surface of the shaft intermediate material 11 under the control of the computer program. By doing this, the required grooves as shown in FIG. 2 are sequentially formed, and finally the required grooves as shown in FIG. 1, that is, the grooves for generating dynamic pressure, can be formed. can.

When the required grooves are formed on the outer surface of the rotating shaft intermediate material by irradiation with a laser beam as described above, burr-like raised areas may appear on the periphery of the grooves, so these should be removed by grinding. The outer diameter of the shaft intermediate material is finished to the required dimensions while being removed by machining or super-finishing. In this way,
A hydrodynamic bearing shaft having required grooves formed on the outer surface is obtained.

According to the groove processing method of the present invention, the laser beam is moved in the axial direction while rotating the shaft intermediate material intermittently and irradiates only the necessary areas, so even though the outer surface is a curved surface, the scanning direction of the laser beam It has the advantage of simplifying the In addition, since the irradiation position of the laser beam and the intermittent irradiation can be easily controlled using a computer, there is no need for complicated processes such as creating new photo etching masks and electrical discharge machining electrodes, which were required in conventional groove processing methods. Even when a unique groove pattern is required or when the design of the groove pattern is frequently changed, there is an advantage that it can be accommodated by devising or changing the computer program. Furthermore, burrs caused by the raised edges of the groove during laser beam processing can be completely removed by forming grooves on the outer surface of the shaft intermediate material and then finishing the outer surface of the shaft intermediate material. Since it can be removed, it has the advantage of making it easy to create highly accurate grooves.

Further, since the groove machining method of the present invention is applied when the material of the shaft is stainless steel, there is less occurrence of burrs on the raised edge of the groove, and highly accurate grooves can be easily machined.

Furthermore, even when the outer surface shape changes in various ways, complex groove patterns for generating dynamic pressure can be efficiently machined, mass production is excellent, processing costs are relatively low, and the quality of the resulting products is uniform. It has excellent characteristics such as.

Note that the shape of the outer surface of the shaft on which the grooves for generating dynamic pressure are to be formed is not limited to the cylindrical surface shown in the embodiment, but may be a spherical surface, a conical surface, or any other curved surface. This groove processing method can be implemented.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an example of a completed shaft for a hydrodynamic bearing, FIG. 2 is an explanatory view showing an embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along line I to I in FIG. 2. FIG. 4 is an explanatory diagram for showing intermittent laser beam irradiation. Explanation of the symbols: 1 is a shaft for a hydrodynamic bearing, 2 and 3 are grooves for generating dynamic pressure, 4 is a laser beam, 11 is an intermediate material for a shaft for a hydrodynamic bearing, 21 and 31 are for generating a dynamic pressure during the forming process. groove.

Claims (1)

[Claims] 1 A shaft intermediate material for a dynamic pressure fluid bearing made of stainless steel pre-processed to the same or slightly larger dimensions as the finished size is intermittently rotated around the shaft center to apply a required dynamic pressure to the outer surface of the shaft intermediate material. The laser beam is moved in the axial direction of the shaft while controlling the irradiation position and intermittent irradiation of the laser beam using a computer program created for processing grooves for generation, and irradiates only the necessary areas on the outer surface. A method for machining grooves on a shaft for a hydrodynamic bearing, characterized in that a groove for generating a required dynamic pressure is formed in the shaft, and then the outer surface of the shaft intermediate material is finished to the required dimensions.