KR100267250B1 - Method of forming grooves for generating dynamic pressure in air bearing apparatus - Google Patents

Abstract

PURPOSE: A method and an apparatus for forming dynamic pressure generation grooves of a pneumatic bearing apparatus are provided to reduce the manufacturing cost and time by processing the dynamic pressure generation grooves with a sand blast process, and easily form the dynamic pressure generation grooves by appropriately controlling the depth of the dynamic pressure generation grooves. CONSTITUTION: A method for forming dynamic pressure generation grooves of a pneumatic bearing apparatus includes the steps of forming a hemisphere by bisecting a sphere(100) and forming a surface by cutting the upper part of the hemisphere at a predetermined height to be parallel with the reverse, forming a through hole passing through the center of the surface and the reverse, inserting and fixing a jig connected with a motor(175) into the through hole, fixing a mask(190) covering the surface of the hemisphere and having apertures(195) corresponding to dynamic pressure generation grooves formed at the side surface of the hemisphere to cover the whole surface of the hemisphere, and ejecting the high pressure air(182) including fine solid particles to the mask with rotating the hemisphere.

Description

Method of forming grooves for generating dynamic pressure in air bearing apparatus

The present invention relates to a method and a device for forming a dynamic pressure generating groove of an air bearing device, and more particularly, by processing the dynamic pressure generating groove of the air bearing device by a sand blast to reduce processing time and reduce manufacturing cost. The present invention relates to a method and a device for forming a dynamic pressure generating groove of an air bearing device.

Recently, due to the rapid development of the electronics and mechanical industries, driving devices requiring ultra-high rotational performance, for example, a scanning motor of a laser printer, a spindle motor of a hard disk driver, or a head drive motor of a VCR, etc., are used due to the characteristics of the device. In order to perform more data retrieval, storage and regeneration in a shorter time, there is a demand for high-precision, ultra-fast rotational performance without shaft shaking or shaft vibration.

Accordingly, research and development of various types of control ring devices have been actively conducted to improve the rotational performance of the motor and to develop a driving motor that stably rotates at high speed while suppressing shaft shaking and shaft vibration of the driving motor. .

This type of bearing device is widely used as an air bearing device that has superior performance than a ball bearing that reduces friction by solid friction and has been proven to have high speed and high precision stability. The principle of boundary friction between and solid is applied.

Depending on the unique characteristics of the machine, various kinds of air bearing devices can be used, but in particular, hemispherical and conical bearing devices, which are suitable for high speed and high precision rotation and simultaneously support the radial and thrust loads of the rotating body, are widely used. have.

For example, the hemispherical bearing device is formed with a spiral-like dynamic pressure generating groove for generating a predetermined air pressure on either side of the hemisphere and the bushing so that boundary friction acts between the hemisphere fixed to the shaft and the bushing. At this time, it is known that a large difference occurs in performance depending on the position of the dynamic pressure generating groove and the area of the dynamic pressure generating groove.

With reference to the accompanying drawings, a method of forming a dynamic pressure generating groove on the hemisphere to generate dynamic pressure in the hemisphere bearing device which is one of such air bearing devices will be described as an example.

First, as shown in Figure 1, after manufacturing the hollow sphere through the machining or forging process, after dividing the sphere into half hemispheres 100, and then cut the upper part of the hemisphere by a predetermined height back Form surface 110 to be parallel to 120. Subsequently, a through hole 110 having a predetermined diameter is formed to penetrate the surface 110 and the rear surface 120. A shaft (not shown) is press-fitted into the through hole 110 to fix the hemisphere 100.

Meanwhile, a preliminary machining process is performed on the hemispherical surface 140 of the hemisphere 100 formed as described above through a lapping process and a polishing process so that surface roughness and sphericity are within an allowable tolerance.

Referring to FIG. 2, a photoresist (hereinafter referred to as PR) is uniformly coated on the hemispherical surface 140 of the hemisphere 100 in which the preliminary processing step is completed, and then applied to the hemisphere surface 140. After exposing and developing processes to expose only the portion where the dynamic pressure generating groove 150 is to be formed by using a mask (not shown) having a corresponding shape, the wafer is etched using a predetermined solvent.

At this time, the area determined by the depth and width of the dynamic pressure generating groove 150 is closely related to the size of the dynamic pressure, in order to obtain an area equivalent to the design value, careful attention should be paid to the composition ratio of the solvent, etching time and the like.

Subsequently, after a predetermined time has elapsed, the hemisphere 100 is washed to remove the photoresist 120 covering the hemisphere 100 of the hemisphere 100.

On the other hand, since the material of the hemisphere 100 is mainly a light alloy material such as an aluminum alloy, TiN (titanium nitride), a wear protection layer that is resistant to abrasion and increases the smoothness of the surface, in order to prevent wear due to contact with the bushing, 140) is coated using a chemical vapor deposition method or the like. In addition, in order to reduce the coefficient of friction, DLC (Diamond-Like-Carbon) may be coated with a thickness of several μm on top of TiN.

However, according to the conventional method of forming a dynamic pressure generating groove, there are some problems.

First, since the dynamic pressure generating groove is formed by using the etching process, there is a problem in that the number of processing steps is large. That is, the operation is cumbersome because the photoresist is applied, exposed, developed and etched using a mask, and the photoresist must be removed again.

Secondly, in order to accurately form the area of the dynamic pressure generating groove, it is difficult to process because the composition ratio and time of the solvent must be precisely controlled.

Third, the processing time according to the etching is long, there is a problem that the manufacturing cost rises due to the etching equipment.

Accordingly, it is an object of the present invention to provide a method and apparatus for forming a dynamic pressure generating groove for easy processing, reducing processing time, and reducing manufacturing cost.

1 to 2 is a process diagram showing a method for forming a dynamic pressure generating groove of a conventional air bearing device,

3 is a cross-sectional view showing a polygon mirror driving apparatus to which an air bearing apparatus according to the present invention is applied;

Figure 4 is a process chart showing a dynamic pressure generating groove forming method of the air bearing apparatus according to the present invention.

<Description of Symbols for Main Parts of Drawing>

100: hemisphere 110: surface of the hemisphere

120: back side of hemisphere 140: hemisphere

150: dynamic pressure generating groove 170: control unit

175: motor 180: sand blast

182: high pressure air 190: metal mask

195: opening

According to the forming method of the present invention, the dynamic pressure generating member is processed into a predetermined shape, and the front surface of the dynamic pressure generating member is covered with a mask in which openings corresponding to the dynamic pressure generating grooves are formed, and then the fine solid particles are included in the mask. Spray high pressure air.

Preferably, the dynamic pressure generating member is rotated simultaneously with the injection of the high pressure air, wherein the injection pressure of the high pressure air and the rotational speed of the dynamic pressure generating member are controlled in relation to each other.

The dynamic pressure generating member may be hemispherical or conical in shape.

The high pressure air may also contain sand or glass.

Meanwhile, according to the dynamic pressure generating groove forming apparatus of the present invention, a jig for fixing the dynamic pressure generating member, a motor for rotating the jig, a mask covering the front surface of the dynamic pressure generating member and having openings corresponding to the dynamic pressure generating grooves, respectively; And a sand blast for injecting high pressure air including sand into the mask, and a control unit for controlling the motor and the sand blast.

Preferably, the height of the mask is greater than the height of the dynamic pressure generating member, and one end of the openings formed in the mask coincides with the bottom surface of the dynamic pressure generating member.

In addition, the mask may be a metal material, and titanium nitride (TiN) and DLC (Diamond-Like-Carbon) may be sequentially coated on the entire surface of the mask.

Hereinafter, a method of forming a dynamic pressure generating groove of an air bearing device according to the present invention will be described with reference to the accompanying drawings.

First, a polygon mirror driving device to which an air bearing device having a dynamic pressure generating groove is formed on a hemisphere will be described.

Referring to FIG. 3, the polygon mirror driving apparatus generally includes a shaft 20 which is the rotation center of the polygon mirror 10, and a pair of hemispheres 30 and 35 that are forcibly fitted to the shaft 20. And a cylindrical bushing 40 having hemispherical grooves 30a and 30b formed at both ends thereof so as to simultaneously support the radial load and the thrust load of the hemisphere 100, the rotor 50 and the stator as driving devices. And a lower bearing bracket 70 to which the polygon mirror 10 and the rotor 50 are mounted and fixed to the bushing 40, and one end of the shaft 20 is fixed.

Hemispherical grooves 30a and 30b having the same shape as the curvature of the hemisphere 100 are formed on both end surfaces of the bushing 40, and through holes are formed to communicate with the hemisphere grooves 30a and 30b, and the hemispheres are formed in the through holes. The spacer 40a for adjusting the gap between the 100 and the hemisphere grooves 30a and 30b is inserted.

Hereinafter, a method of forming a dynamic pressure generating groove of an air bearing apparatus according to the present invention will be described in detail with reference to FIG. 4. In this embodiment, a hemisphere bearing device is taken as an air bearing device.

As described above with reference to Figure 1, after manufacturing the hollow sphere through the machining or forging process, after dividing the sphere into half hemispheres 100, and then cut the upper part of the hemisphere by a predetermined height Form surface 110 to be parallel to 120. Subsequently, a through hole 110 having a predetermined diameter is formed to penetrate the surface 110 and the rear surface 120.

On the other hand, the hemisphere surface 140 formed as described above is subjected to a preliminary processing process so that the surface roughness and sphericity within the tolerance through the lapping process and polishing process.

Subsequently, the through holes of the processed hemispheres 100 are fixed to the jig 200. The jig 200 is connected to the motor 175 to rotate at a predetermined speed according to the rotation of the motor 175. In addition, the motor 175 rotates constantly while maintaining a predetermined speed under the control of the controller 170 as described below.

After fixing the hemisphere 100 on the jig 200, the front surface of the hemisphere 100 is covered using the metal mask 190. The metal mask 190 has an opening 195 formed at a position corresponding to the dynamic pressure generating groove 150 formed on the hemisphere 100, and has a curvature that is exactly matched with the hemisphere 100. In addition, the height of the metal mask 190 is greater than the height of the hemisphere 100 so that the end portion protrudes more than the back surface 120 of the hemisphere 100 in a state covering the hemisphere 100. Accordingly, one end of the opening 195 of the metal mask 190 is exactly coincident with the back surface 120 of the hemisphere 100 so that the dynamic pressure generating groove 150 is the same as the back surface 120 of the hemisphere 100. Can be formed at the level.

Subsequently, the high pressure air 182 is ejected from the sand blast 180 while driving the motor 175 under the control of the controller 170 to rotate the jig 200 at a constant speed. The high-pressure air 182 includes fine sand, glass, and the like, so as to impact the hemisphere 100 made of aluminum at a high pressure, the dynamic pressure generating groove 150 corresponding to the opening 195 of the metal mask 190. ), And the other part is covered with a high-strength metal mask 190 and is not affected by the sand blast 180.

The mask 190 may be coated with TiN (titanium nitride), which is preferably abrasion resistant, and is coated with DLC (Diamond-Like-Carbon) to a thickness of several μm, thereby further improving strength.

On the other hand, the width and length of the dynamic pressure generating groove 150 to be formed is determined by the opening 195 of the mask 190, the length of the mask from the nozzle of the sand blast 180 is ejected from the high pressure air 182 By adjusting the injection angle by adjusting the distance to 190, it is possible to form one dynamic pressure generating groove 150 by one injection. In addition, the depth of the dynamic pressure generating groove 150 can be appropriately controlled by adjusting the injection pressure of the high pressure air 182 or the rotational speed of the motor 175.

After forming the dynamic pressure generating groove 150 as described above, the metal mask 190 is peeled off and separated from the jig 200 to complete the processing.

On the other hand, in order to prevent abrasion in contact with the bushing, to prevent the wear and to increase the smoothness of the surface TiN (titanium nitride), which is a wear protection layer to increase the smoothness of the surface or to reduce the coefficient of friction To this end, DLC (Diamond-Like-Carbon) may be coated with a thickness of several μm on top of TiN.

As described above, the present invention has various advantages.

First, since the sand blast is simply used to form the dynamic pressure generating groove, an expensive etching equipment is not required, and thus manufacturing cost is reduced.

Second, the dynamic pressure generating groove forming process is simpler than the case by etching, and thus the processing time is reduced.

Third, the depth of the dynamic pressure generating groove can be controlled appropriately by adjusting the rotational speed of the rotating motor by fixing the pressure or hemisphere of the high pressure air injected from the sand blast to accurately form the area of the dynamic pressure generating groove. Do.

In the above, the method of forming the dynamic pressure generating groove by using the hemisphere as an example has been described, but the same can be applied to the conical shape and other shapes by changing the shape of the mask.

Therefore, the technical idea of the present invention can be embodied in various forms by those skilled in the art, and the configuration thus implemented is included in the present invention without departing from the spirit of the present invention.

Claims (9)

Bisecting the hollow sphere to form a hemisphere, and cutting the parallel to the back surface at a predetermined height from the back surface of the hemisphere to form a surface; Forming a through hole penetrating the center of the surface and the back surface; Inserting and fixing a jig connected to a motor to the through hole; A cover covering the surface of the hemisphere and fixed to cover the front surface of the hemisphere with a mask having openings corresponding to dynamic pressure generating grooves respectively formed on the side surface of the hemisphere; A method of forming a dynamic pressure generating groove of an air bearing apparatus, comprising: spraying a high pressure air including fine solid particles in the mask while rotating the hemisphere. The method of claim 1, wherein the injection pressure of the high-pressure air and the rotational speed of the dynamic pressure generating member are controlled in relation to each other. The method of claim 1, wherein the fine solid particles are sand. 2. The method of claim 1, wherein the fine solid particles are glass. A jig for fixing a hemisphere having a back surface and a surface parallel to each other and a through hole passing through a center of the back surface and the surface; A motor coupled to the jig to rotate the hemisphere at a predetermined speed; A mask covering the surface of the hemisphere and having openings corresponding to dynamic pressure generating grooves respectively formed on the side surface of the hemisphere, and mounted to cover the front surface of the hemisphere; And a sand blast for injecting high pressure air including solid particles into the mask, and a controller for controlling the rotational speed of the motor and the injection pressure of the sand blast. 6. The apparatus of claim 5, wherein the height of the mask is greater than the height of the hemisphere. 7. The apparatus of claim 6, wherein one end of the openings formed in the mask coincides with the bottom surface of the hemisphere. 6. The dynamic pressure generating groove forming apparatus of claim 5, wherein the mask is made of metal. [9] The apparatus of claim 8, wherein titanium nitride (TiN) and DLC (Diamond-like-Carbon) are sequentially coated on the front surface of the mask.

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