US20060205327A1

US20060205327A1 - Polishing apparatus and method

Info

Publication number: US20060205327A1
Application number: US11/369,652
Authority: US
Inventors: Kuo-Cheng Huang; Jung-Ru Yu; Ching-Hsiang Kuo
Original assignee: Individual
Current assignee: National Science Council
Priority date: 2005-03-08
Filing date: 2006-03-07
Publication date: 2006-09-14
Also published as: TWI292731B; TW200631732A

Abstract

The present invention provides a polishing apparatus and a polishing method, which are particular for the non-spherical lens. The polishing apparatus includes a base for carrying an object; and a polishing head, wherein the polishing head has a polishing layer made of a resin, a diamond and a graphite for polishing the object; a buffer layer connected to the polishing layer for the polishing head to tilt and shift; and a shaft connected to the buffer layer.

Description

FIELD OF THE INVENTION

The present invention relates to a polishing apparatus and a polishing method thereof, and more particularly to the polishing apparatus for non-spherical lens.

BACKGROUND OF THE INVENTION

The manufacturing process of an optic lens can be divided into several steps, including shaping, grinding and polishing. Some processes include a traditional spherical lens process, a diamond single-point cutting process and a glass molding process.
The traditional process of a spherical optic lens is to contact and polish the lens with a polishing mold having the same curvature as the lens. A lens having an even and precision surface is then obtained. However, the process can not be used for making a non-spherical lens. Further, it costs a lot of time to fabricate optic lenses through the diamond grinding. The diamond grinding is also easy to be abraded, thereby affecting the precision of the surface.
For a non-spherical lens, because of the variation of the surface curvature, the precision of the shape and the roughness of the surface can not be amended and improved by a spherical mold. Therefore, a non-spherical lens is grinded and polished by a small surface contact method or a single-point cutting method. However, the process can not grind, polish and amend the error of the shape in a larger surface, and thus it costs more time to make a non-spherical lens than a spherical lens having the same size. Because the pressure during the polishing process is not distributed equally on the surface, extremely tinny lines are formed on the surface of a lens and the quality of a polished surface is not desirable. The glass molding process is also used for making a non-spherical lens. However, the mold requires high precision, and it costs lots of time and money to build the mold. Therefore, the glass molding process is used in a mass production to meet the cost. Thus, the glass molding process is not suitable for fabricating a non-spherical lens having a larger caliber.
In order to meet the requirements of the non-spherical lens and overcome the drawbacks of the above processes, the present invention provides a polishing apparatus and method thereof.

SUMMARY OF THE INVENTION

It is an aspect of the present invention to provide a polishing apparatus. The polishing apparatus includes a base for carrying an object thereon; and a polishing head located above the base. The polishing head includes a polishing layer for polishing the object; a buffer layer connected to the polishing layer for the polishing head to tilt and shift; and a shaft connected to the buffer layer.
According to the present invention, the polishing layer is made of a material selected from the group consisting of a resin, an abrasive particle and graphite.
Preferably, the abrasive particle is one selected from the group consisting of a diamond, a silicon carbide (SiC) and a cubic boron nitride (CBN).
Preferably, a particle size of the abrasive particle is ranged from #800 to #4000.
Preferably, an amount of the graphite is ranged from 25% to 35% by weight in the polishing layer.
According to the present invention, the shaft is a metal shaft.
According to the present invention, the polishing layer further includes a diversion channel.
More preferably, the diversion channel contains a polishing slurry located therein.
More preferably, the diversion channel includes at least one opening for discharging the polishing slurry.
According to the present invention, the buffer layer has a material being one selected from the group consisting of sponges, elastic gels, and springs.
According to the present invention, the object is a non-spherical lens.
It is another aspect of the present invention to provide a polishing head for polishing an object. The polishing head includes a polishing layer and a buffer layer connected to the polishing layer for the polishing head to tilt and shift.
According to the present invention, the polishing layer is made of materials comprising a resin, an abrasive particle, and a graphite.
Preferably, the abrasive particle is one selected from the group consisting of a diamond, a silicon carbide (SiC) and a cubic boron nitride (CBN).
Preferably, a particle size of the abrasive particle is ranged from #800 to #4000.
Preferably, an amount of the graphite is ranged from 25% to 35% by weight in the polishing layer.
According to the present invention, the polishing layer further includes a diversion channel.
Preferably, the diversion channel contains a polishing slurry located therein.
More preferably, the diversion channel includes at least one opening for discharging the polishing slurry.
According to the present invention, the buffer layer has a material being one selected from the group consisting of sponges, elastic gels, and springs.
According to the present invention, the object is a non-spherical lens.
It is a further aspect of the present invention to provide a polishing method. The method includes the steps of providing the polishing apparatus according to the present invention, the object having a first central curvature radius R and a first conic constant K, making the polishing head to have a second central curvature radius R±ΔR and a second conic constant K±ΔK, and polishing the object with the polishing head.
According to the present invention, the ΔR is ranged from 0.001 R to 0.1 R and the ΔK is ranged from 0.001K to 0.1K.
According to the present invention, the object is a concave object.
According to the present invention, the object is a convex object.
It is further another aspect of the present invention to provide a polishing method. The method includes the steps of providing an object having a first central curvature radius R and a first conic constant K, providing a polishing head having a second central curvature radius R±ΔR, and a second conic constant K±ΔK, and polishing the object with the polishing head. The ΔR is ranged from 0.001 R to 0.1 R and the ΔK is ranged from 0.001K to 0.1K.
According to the present invention, the object is a concave object.
According to the present invention, the object is a convex object.
The above aspects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing the polishing head of the first preferred embodiment of the present invention;
FIG. 2 is a schematic view showing the polishing layer of the first preferred embodiment of the present invention;
FIG. 3 is a schematic view showing the function of the buffer layer of the first preferred embodiment of the present invention;
FIG. 4 is a schematic view showing the polishing apparatus of the second preferred embodiment of the present invention;
FIG. 5(a) is a schematic view showing the polish of a convex lens;
FIG. 5(b) is a schematic view showing the polish of a concave lens;
FIG. 6(a) is a schematic view showing the amended polish of a convex lens;
FIG. 6(b) is a schematic view showing the amended polish of a concave lens;
FIG. 7(a) is a schematic view showing the amended polish of a convex lens;
FIG. 7(b) is a schematic view showing the amended polish of a concave lens;
FIG. 8(a) is a schematic view showing the amended polish of a convex lens; and
FIG. 8(b) is a schematic view showing the amended polish of a concave lens.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention is described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for the purposes of illustration and description only; it is not intended to be exhaustive or to be limited to the precise form disclosed.
Please refer to FIG. 1, which is a schematic view showing the polishing head of the first preferred embodiment of the present invention. The polishing head 1 according to the present invention includes a polishing layer 11, a buffer layer 12, a metal layer 13 and a metal shaft 14. The polishing layer 11 is made of a resin diamond sintered by a resin and an abrasive particle, and a graphite is added into the resin diamond to form the polishing layer 11. A particle size of the abrasive particle is ranged from #800 to #4000. The abrasive particle is one selected from the group consisting of a diamond, a silicon carbide (SiC) and a cubic boron nitride (CBN). An amount of the graphite is ranged from 25% to 35% by weight in the polishing layer 11. The lubricity during polishing is increased because of the addition of the graphite in the polishing layer 11.
Please refer to FIG. 2, which is a schematic view showing the polishing layer 11 of the first preferred embodiment of the present invention. The polishing layer 11 further includes a diversion channel 111 and an opening 112, wherein the diversion channel 111 contains a polishing slurry located therein and the polishing slurry is discharged from the opening 112. Please refer to FIG. 3, which is a schematic view showing the function of the buffer layer 12 of the first preferred embodiment of the present invention. The buffer layer 12 is made of a material being one selected from the group consisting of sponges, elastic gels, and springs. Because the buffer layer 12 is a soft material capable of being transformed slightly, the polishing head 1 has a little liberty to tilt and shift. The upper part of FIG. 3 shows the shift of the polishing head 1, and the lower part of FIG. 3 shows the tilt of the polishing head 1.
Please refer FIG. 4, which is a schematic view showing the polishing apparatus of the second preferred embodiment of the present invention. The polishing apparatus according to the present invention includes a base 41 and a polishing head 43, wherein the polishing head 43 includes a polishing layer 431, a buffer layer 432 and a metal shaft 433. The base 41 is used for carrying an object 42 thereon. The polishing head 43 is located above the base 41. The buffer layer 432 is connected to the polishing layer 431. The metal, shaft 433 is connected to the buffer layer 432.
The polishing layer 431 is made of a resin diamond sintered by a resin and an abrasive particle, and a graphite is added into the resin diamond to form the polishing layer 431. A particle size of the abrasive particle is ranged from #800 to #4000. The abrasive particle is one selected from the group consisting of a diamond, a silicon carbide (SiC) and a cubic boron nitride (CBN). An amount of the graphite is ranged from 25% to 35% by weight in the polishing layer 431. The lubricity during polishing is increased because of the addition of the graphite in the polishing layer 431.
The buffer layer 432 is made of a material being one selected from the group consisting of sponges, elastic gels, and springs. Because the buffer layer 432 is a soft material capable of being transformed slightly, the polishing head 43 has a little liberty to tilt and shift.
The polishing layer 431 further includes a diversion channel 4311 and an opening 4312, wherein the diversion channel 4311 contains a polishing slurry located therein and the polishing slurry is discharged from the opening 4312 to be the lubricant during polishing.
The present invention is not only used for polishing a general spherical lens, but also suitable for polishing a non-spherical lens. Please refer to FIG. 4, which shows polishing an object 42, e.g. a non-spherical lens, with the polishing apparatus 4 according to the present invention. There is a diversion pathway (not shown) in the metal shaft 433 to provide a polishing slurry flowing into the polishing layer 431. Then the polishing slurry flows to the surface of the object 42 through the opening 4312. Besides, the buffer layer 432 is a soft material capable of being transformed slightly, and therefore the polishing head 43 has a little liberty to tilt and shift. Therefore, the polishing layer 431 can be close engaged with the object 42. Then, the object 42 is grinded, cut and polished with the diamond particle in the polishing layer 431 to remove digs and scratches on the surface thereof. Furthermore, the polishing slurry is filled equally between the surfaces of the polishing layer 431 and the object 42 in the polishing apparatus according to the present invention, and thus the efficiency and stability of the polishing is increased.
According to the present invention, if the object being polished is a concave object having a central curvature radius R, it is suggested to adjust the polishing head to have a central curvature radius R±ΔR to obtain the best efficiency of polishing. The ΔR is equal to CR, and the C is ranged from 0.001 to 0.1, wherein the value of C should be dependent on the actual size of the object. If the object being polished is a convex object having a central curvature radius R, it is suggested to adjust the polishing head to have a central curvature radius R±ΔR to obtain the best efficiency of polishing. The ΔR is equal to CR, and the C is ranged from 0.001 to 0.1, wherein the value of C should be dependent on the actual size of the object.
The conic constant K of the polishing head is also adjusted as K±ΔK. The ΔK is equal to DK, and D is ranged from 0.001 to 0.1, wherein the value of D should be dependent on the actual size of the object.
The polishing apparatus according to the present invention can not only polish an object evenly, but also amend the error during polishing precisely. It is described in detail as follows.
While operating the polishing apparatus according to the present invention, the polishing layer having different particle size is chosen according to the size and uniformity of scars and punctures on the surface of the object. An advanced polishing is proceeded, and the polishing head contacts the object gradually and polishes the whole lens by the mechanism of slight tilting and shifting of the polishing head. Therefore, the present invention is suitable for polishing a non-spherical lens.
After the object is polished evenly, the precision of the surface shape of the object is measured to be the basis for amended polishing. Please refer to FIGS. 5(a) and 5(b), which show the schematic views of the polish of a convex lens and a concave lens, respectively. As shown in the figures, the surface of the lens is divided into three areas (I-II-III). Please refer to FIGS. 6(a) and 6(b), which are schematic views showing the amended polish of a convex lens and a concave lens respectively. According to the result of measuring the lens, when the area I needs to amend the error, the polishing head is moved close to the area I. As shown in FIG. 6(a), the polishing head is tilted an angle φ and shifted a distance δ1. The polishing head contacts the convex lens at the area I and sways to contact the area I evenly. The amended polish of the area I is proceeded in a controlled time, wherein the δ1 and φ1 are adjusted for the polishing head to contact the area I. While the area II of the lens needs to amend the error, please refer to FIGS. 7(a) and 7(b), which are schematic views showing the amended polish of a convex lens and a concave lens respectively. As shown in FIGS. 7(a) and 7(b), when the area II needs to amend the error, the polishing head is moved close to the area II. The polishing head is tilted an angle φ2 and shifted a distance δ2 gradually according to the error of the lens. The polishing head then contacts the lens at the area II. Because the buffer layer of the polishing layer is a soft material capable of being transformed slightly, the polishing head has a little liberty to tilt and shift. The polishing head is also swayed to contact and polish the area II of the leans closely. While the area III of the lens needs to amend the error, please refer to FIGS. 8(a) and 8(b), which are schematic views showing the amended polish of a convex lens and a concave lens respectively. As shown in FIG. 8(b), when the area III needs to amend the error, the polishing head is moved close to the area III. The polishing head is tilted an angle φ3 gradually and shifted a distance δ3 according to the error of the lens. The polishing head then contacts the lens at the area III. As described above, the polishing layer is transformed slightly by the buffer layer. The polishing head is swayed to contact and polish the area III of the leans closely. As mentioned above, because the polishing apparatus according to the present invention has a slightly-transformable polishing head, which can tilt and shift according to different situations of the surface of an object, the polishing apparatus according to the present invention has a high polishing efficiency.
The polishing head according to the present invention has a polishing layer, which is made of a resin diamond. The polishing head can perform a polish delicately. The polishing head further includes a slightly-transformable buffer layer, and therefore the polishing head according to the present invention has a mechanism to tilt and shift slightly. The polishing head can contact and polish the object closely. As mentioned above, the present invention has a high efficiency to polish a spherical lens. The present invention especially provides a polishing apparatus and method for a non-spherical lens, which can correct the precision of the shape of a lens and reduce the roughness of the surface thereof.
While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.

Claims

1. A polishing apparatus, comprising:

a base for carrying an object thereon; and

a polishing head located above said base, wherein said polishing head comprises:

a polishing layer for polishing said object;

a buffer layer connected to said polishing layer for said polishing head to tilt and shift; and

a shaft connected to said buffer layer.

2. The polishing apparatus according to claim 1, wherein said polishing layer is made of a material selected from the group consisting of a resin, an abrasive particle and a graphite.

3. The polishing apparatus according to claim 2, wherein said abrasive particle is one selected from the group consisting of a diamond, a silicon carbide (SiC) and a cubic boron nitride (CBN).

4. The polishing apparatus according to claim 2, wherein a particle size of said abrasive particle is ranged from #800 to #4000.

5. The polishing apparatus according to claim 2, wherein an amount of said graphite is ranged from 25% to 35% by weight in said polishing layer.

6. The polishing apparatus according to claim 1, wherein said shaft is a metal shaft.

7. The polishing apparatus according to claim 1, wherein said polishing layer further comprises a diversion channel.

8. The polishing apparatus according to claim 7, wherein said diversion channel contains a polishing slurry located therein.

9. The polishing apparatus according to claim 8, wherein said diversion channel comprises at least one opening for discharging said polishing slurry.

10. The polishing apparatus according to claim 1, wherein said buffer layer has a material being one selected from the group consisting of sponges, elastic gels, and springs.

11. The polishing apparatus according to claim 1, wherein said object is a non-spherical lens.

12. A polishing head for polishing an object, comprising:

a polishing layer; and

a buffer layer connected to said polishing layer for said polishing head to tilt and shift.

13. The polishing head according to claim 12, wherein said polishing layer is made of materials comprising a resin, an abrasive particle, and a graphite.

14. The polishing head according to claim 13, wherein said abrasive particle is one selected from the group consisting of a diamond, a silicon carbide (SiC) and a cubic boron nitride (CBN).

15. The polishing head according to claim 13, wherein a particle size of said abrasive particle is ranged from #800 to #4000.

16. The polishing head according to claim 13, wherein an amount of said graphite is ranged from 25% to 35% by weight in said polishing layer.

17. The polishing head according to claim 12, wherein said polishing layer further comprises a diversion channel.

18. The polishing head according to claim 17, wherein said diversion channel contains a polishing slurry located therein.

19. The polishing head according to claim 18, wherein said diversion channel comprises at least one opening for discharging said polishing slurry.

20. The polishing head according to claim 12, wherein said buffer layer has a material being one selected from the group consisting of sponges, elastic gels, and springs.

21. The polishing head according to claim 12, wherein said object is a non-spherical lens.

22. A polishing method, comprising steps of:

providing said polishing apparatus according to claim 1, wherein said object has a first central curvature radius R and a first conic constant K;

making said polishing head to have a second central curvature radius R±ΔR and a second conic constant K±ΔK; and

polishing said object with said polishing head.

23. The polishing method according to claim 22, wherein said ΔR is ranged from 0.001 R to 0.1 R and said ΔK is ranged from 0.001K to 0.1K.

24. The polishing method according to claim 22, wherein said object is a concave object.

25. The polishing method according to claim 22, wherein said object is a convex object.

26. A polishing method, comprising steps of:

providing an object having a first central curvature radius R and a first conic constant K;

providing a polishing head having a second central curvature radius R±ΔR, and a second conic constant K±ΔK, wherein said ΔR is ranged from 0.001 R to 0.1 R and said ΔK is ranged from 0.001K to 0.1K; and

polishing said object with said polishing head.

27. The polishing method according to claim 26, wherein said object is a concave object.

28. The polishing method according to claim 26, wherein said object is a convex object.