1. Field of the Invention
The invention relates to a method for manufacturing bearing assembly, and more particularly, to a method for manufacturing bearing assembly with pressure-generating grooves in photolithography process.
2. Description of the Related Art
A dynamic bearing comprises fine pressure-generating grooves on the inner walls thereof. As the axle of a motor spins, lubricant in the pressure-generating grooves is drawn to distribute between axle and the bearing and generate dynamical pressure therebetween, which reduces the friction between the axle and the bearing and eliminates the noise due to the friction. The pressure-generating grooves on the inner wall of the bearing, however, are difficult to be fabricated because of the minute scale of width and depth thereof. The costs of conventional manufacturing methods such as cutting, rolling, injection, or combination etc. are very high because these methods need special processing tools and skills. In addition, pressure-generating grooves processed by cutting processing often cause breach at the turning point and have inconsistent depth and width. Furthermore, the expensive processing machine and fragile cutting tools cannot be effectively and efficiently applied to mass production.
Ameliorating the aforementioned problems, the invention provides a method for manufacturing bearing assembly in photolithography process.
According to the invention, a method of manufacturing a bearing assembly is provided. An exemplary embodiment of the method comprises the steps of: providing a bearing having a through hole; applying a photoresist on an inner wall of the through hole of the bearing; providing an ultraviolet lamp capable of entering into the through hole; attaching a mask having patterns of pressure-generating grooves to the surface of the ultraviolet lamp; inserting the ultraviolet lamp into the through hole to expose the photoresist through the mask; removing the exposed portions of photoresist to make its underneath portions of the inner wall appear; etching the appeared portions of the inner wall to form grooves; and stripping the remaining photoresist from the inner wall of the bearing.
According to the exemplary embodiment, the bearing is preferably made of copper.
According to the exemplary embodiment, the photoresist is preferably coated by spray coating, dipping, spin coating or centrifugal coating.
According to the exemplary embodiment, after the photoresist has been coated, a baking step is preferably executed to cure the photoresist.
According to the exemplary embodiment, the ultraviolet lamp preferably comprises cold cathode fluorescent lamp (CCFL) or light optical fiber.
According to the exemplary embodiment, a portion of the mask, the patterns of pressure-generating grooves located, is transparent and the other portion is opaque.
According to the exemplary embodiment, the mask does not only have the groove patterns, but also have a oil reservoir pattern to simultaneously form grooves and the oil reservoir on the inner wall of the through hole in the bearing.
According to the exemplary embodiment, the mask preferably comprises a slice attached to the ultraviolet lamp, or a metal pattern directly formed on the wall of ultraviolet lamp.
According to the exemplary embodiment, a portion of the mask, the groove patterns located, is opaque and the other portion thereof is transparent. An exposed portion of photoresist, such as positive photoresist, is removed by a developer, a deposited layer is then formed on a portion of the inner wall where the photoresist has been removed. The residual positive photoresist on the inner wall is removed by stripping agent to form the grooves between the two adjacent deposited layers. Washing the bearing by water is to complete dynamic bearing.
According to the exemplary embodiment, the deposited layer is preferably made of a wear resistant material which is different from the bearing.
According to the exemplary embodiment, the deposited layer on the portion of the inner wall which is not covered with photoresist is preferably formed by electroplating, sputtering, chemical reaction, or any other suitable manner for forming deposited layers.
According to the exemplary embodiment, a negative photoresist can also be applied to coat on the inner wall to manufacture the bearing. Differences of the steps between examples of using negative and positive photoresists are the following: while the mask with the pattern of grooves is opaque, a portion of the inner wall without covering the photoresist is etched by etchant to a desirable depth to form the bearing with grooves; and while the mask with the pattern of grooves is transparent, a deposited layer is formed on the portion of the inner wall, where the photoresist not covered, by electroplating, sputtering, a chemical reaction, or any other suitable manner for forming deposited layer, to form a dynamic bearing having grooves formed between the two adjacent deposited layers.
The method for manufacturing the bearing assembly according to the invention, a surface of a shaft can be processed by photolithography process to eliminate difficulty in manufacturing fine grooves of small bearing assembly.
According to the method of manufacturing bearing assembly, an exemplary embodiment of the method comprises the steps of: providing a shaft; applying a positive photoresist on a surface of the shaft; providing an ultraviolet lamp with circular shape, and the inner surface thereof attached a mask having patterns of grooves; inserting the shaft into the ultraviolet lamp to expose and produce a photosensitized portion of the positive photoresist corresponding to a transparent portion of the mask; taking the shaft out the lamp and removing the exposed portion of the positive photoresist on the surface of the shaft by a developer; etching the surface of the shaft without covered with the positive photoresist to form a desirable depth; stripping the remaining positive photoresist from the surface of the shaft; and washing the shaft by water to complete manufacture of a dynamic bearing having grooves.
According to the exemplary embodiment, the shaft is preferably made of copper or alloys thereof.
According to the exemplary embodiment, the positive photoresist is preferably coated on the surface of the shaft by spray coating, dipping, spin coating or centrifugal coating. Preferably, a baking step is executed to cure the positive photoresist after the coating step.
According to the exemplary embodiment, the groove pattern of the mask is transparent and the other pattern thereof is opaque.
According to the exemplary embodiment, the mask does not only have the groove patterns, but also have a oil reservoir patterns to simultaneously form grooves and the oil reservoir on the surface of the shaft.
According to the exemplary embodiment, a portion of the mask with the patterns of grooves is opaque and the other portion thereof is transparent. An exposed portion of positive photoresist is removed by a developer to form an appeared surface of the shaft and a deposited layer is then formed on the appeared surface of the shaft. The positive photoresist reminding on the surface of the shaft is removed by a stripping agent to form the grooves between the two adjacent deposited layers. Washing the bearing by water is to complete a dynamic bearing.
According to the exemplary embodiment, the deposited layer is preferably made of a wear resistant material and can be a material which is different from or the same as the bearing.
According to the exemplary embodiment, the deposited layer on the appeared surface of the shaft is preferably formed by electroplating, sputtering, chemical reaction, or any other suitable manner.
According to the exemplary embodiment, a negative photoresist can be in place of the positive photoresist to manufacture the bearing assembly.
In the embodiment, differences of the steps between examples of using negative and positive photoresists are the following: while the mask with the pattern of grooves is opaque, a portion of the surface of the shaft without covering the photoresist is etched by an etchant to a desirable depth to form the bearing having grooves; and while the mask with the pattern of grooves is transparent, a deposited layer is formed on the portion of the surface of the shaft where the photoresist does not cover thereon by electroplating, sputtering, chemical reaction, or any other suitable manner for forming deposited layer so that the bearing having grooves formed between the two adjacent deposited layer.
The method for manufacturing the bearing of the invention, reduces equipment cost, and enables high the throughput. The method is introduced into automation or semi-automation. The dimensions of the formed groove are equal. Any groove shape is formed easily. A typical operator can easily perform the method. Because the manufacturing cost is lower, a medium-small ball bearing and solid lubricating bearing is replaced by a bearing manufactured according to the method of the invention.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
According to the invention, a method of manufacturing bearing at first is to form a desired shape of a bearing having a through hole by cutting or turning or by powder sintering way. The bearing, as shown in
An inner wall 10 defining the through hole is coated with a photoresist 20 uniformly, as shown in
Then, the photoresist 20 coated on the inner wall 10 is dried by baking process for securing the adhesion between the inner wall 10 and the photoresist 20. As shown in
After the exposure process, as shown in
After the developing process, the bearing is cleaned by water. The appeared inner wall 10, the portion of the inner wall 10 uncovering the photoresist 20, is then etched by an etchant to form grooves 12 and an oil reservoir 13 with desirable dimensions. The etchant can comprise ferric chloride, cupric chloride or ammonium sulfide solution.
After the etching process, the bearing is cleaned by water, and the photoresist 20 remaining on the inner wall 10 is stripped by a stripping solution such as alcohol. Then, the bearing is cleaned by water to remove the solutions and expose the grooves 12 and the oil reservoir 13. The finished bearing of the invention is shown in
The feature of the invention is to form the pressure-generating grooves on the inner wall of a bearing by photolithography, so the solutions used in this invention are not limited. In addition, the grooves on the inner wall are also not limited in any shape, and it can be in fish bone shape, substantially-modified-X-shape, twill or straight stripe shape.
According to a second embodiment of the invention, a method for manufacturing the bearing at first is to form a desired shape of a bearing having a through hole and then coat a photoresist on an inner wall of the through hole in the bearing by the similar steps to the first embodiment, as shown in
The photoresist 20 coated on the inner wall 10 can be cured by baking. Alternatively, the photoresist 20 can be cured by natural drying at room temperature.
Furthermore, as shown in
As shown in
After exposing, the lamp 30a is then removed. The photosensitized portion of the positive photoresist 20 is removed by a developer to appear a portion of the inner wall 10, as shown in
Referring to
In
In this embodiment, the deposited layer formed by electroplating is not limited by the depth and width of the pressure-generating groove. Furthermore, the formation of the deposited layer can be modified by adjusting electroplating parameters, for example the electroplating duration, rate of electroplating, electroplating plus current and electroplating liquor additive. As a fragmentary sectional view of the bearing 1 shown in
According to a third embodiment of the invention, a method for manufacturing the bearing is substantially similar to the second embodiment. The formation of the deposited layer, according to the third embodiment of the invention, differs only slightly from the second embodiment. The similar steps, for example modeling, exposing and developing, already described in the second embodiment are not described again here. Note that the bearing 1 in the third embodiment can be metal such as brass, or nonmetal such as aluminum oxide ceramic.
The process of forming the deposited layer of the fourth embodiment of the invention differs only slightly from the second embodiment. The similar steps to the second embodiment, for example modeling, exposing and developing, may refer to
Subsequent to the developing step, a chemical reaction occurs between the surface of the inner wall 10, which is not covered by the photoresist 20, with ambient reactant to form a compound. In this embodiment, the bearing 10 comprising, for example, aluminum or aluminum alloy, is dipped into oxalic acid solvent. In
As shown in (a) of
As shown in (b) of
After exposing, the lamp 30a is removed. A portion of the photoresist 20a without photosensitizing is cleaned by developer and the portion of the inner wall made of copper is appeared, as shown in (c) of
Subsequently, as shown in (d) of
The steps for manufacturing the bearing are substantially the same as the first embodiment, unless the negative photoresist is utilized in this embodiment. Thus, groove pattern of the mask on the lamp in this embodiment is corresponding complement to that in the first embodiment.
As shown in (a) of
As shown in (b) of
After exposing, the lamp 30 is removed. A portion of the photoresist 20a without photosensitizing is cleaned by a developer and the portion of the inner wall made of copper is appeared, as shown in (c) of
As shown in (d) of
This embodiment is the same as the fifth embodiment, unless the groove pattern of the mask on the lamp is transparent. The desirable groove pattern is formed by deposited layers.
In the sixth embodiment, the deposited layer 80 is preferably made of a wear resistant material and is formed by the similar step to the second, third and fourth embodiments.
As shown in (a) of
As shown in (b) of
In this embodiment, the slice is made of a mask 40 with the pressure-generating groove pattern and an area thereof with the pressure-generating groove pattern 401 located is transparent.
After exposing, the shaft is removed from the circular lamp 90. A portion of the photoresist 20 without photosensitizing is cleaned by a developer and the surface of the shaft made of copper is partly appeared, as shown in (c) of
As shown in (d) of
This embodiment is substantially the same as the first embodiment, unless the groove is formed on the surface of the shaft by photolithography and the circular lamp is utilized to expose the surface of the shaft.
As shown in (a) of
As shown in (b) of
After exposing, the shaft is removed from the circular lamp. A portion of the photoresist 20 not photosensitized is cleaned by a developer to appear the surface of the shaft made of copper and form a groove pattern 401a corresponding to the groove pattern of the mask 40a, as shown in (c) of
As shown in (d) of
This embodiment is substantially the same as the seventh embodiment unless the groove pattern of the mask on the lamp is opaque. Thus, the desirable groove pattern is formed by the deposited layer.
In this embodiment, the deposited layer 80 is preferably made of wear resistant material and formed by the similar steps to the second, the third and the fourth embodiments.
As shown in (a) of
As shown in (b) of
After exposing, the shaft is removed from the circular lamp. A portion of the photoresist 20a not photosensitized is cleaned by a developer to appear the surface of the shaft made of copper and form a groove pattern 401a corresponding to the groove pattern of the mask 40a, as shown in (c) of
As shown in (d)
This embodiment is substantially the same as the eighth embodiment unless the photoresist is the negative photoresist. Thus, the groove is formed on exterior surface of the shaft by etching.
As shown in (a) of
As shown in (b) of
After exposing, the shaft is removed from the circular lamp 90. A portion of the photoresist 20a not photosensitized is cleaned by a developer to appear the surface of the copper shaft and form a groove pattern 401 corresponding to the groove pattern of the mask 40, as shown in (c) of
As shown in (d) of
While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Number | Date | Country | Kind |
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95130275 | Aug 2006 | TW | national |
This application is a Continuation-In-Part of pending U.S. patent application Ser. No. 11/405,631, filed Apr. 18, 2006 and entitled “DYNAMIC BEARING MANUFACTURING METHOD”, and claims priority under 35 U.S.C. §119(a) on Patent Application No. 095130272 filed in Taiwan, Republic of China on Aug. 17, 2006, the entire contents of which are hereby incorporated by reference.
Number | Date | Country | |
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Parent | 11405631 | Apr 2006 | US |
Child | 11889946 | Aug 2007 | US |