grinder

Abstract

To provide a polishing machine that enables a surface to be formed in a shape with high precision to make the whole surface smooth, so that the surface is not scratched, in polishing an aspheric surface or a free-form surface.SOLUTION: A polishing machine 10, which can polish a surface W1 to be polished of a work-piece having a free-form surface, comprises: a rotary holding part 20 that rotatably holds the work-piece with a rotary shaft line C as a center; a polishing liquid supply part 25 that supplies the surface to be polished with polishing liquid; a hydrostatic pressure supply part 50; and a polishing part 30 that polishes the surface to be polished. The polishing part comprises a plurality of uniform load polishing parts 40 which have expanding / retracting parts 41 that can expand and retract in nearly parallel to the rotary shaft line with respect to the surface to be polished, polishing pads 43 provided at end parts made adjacent to the surface to be polished of the expanding / retracting parts, and hydrostatic pressure applying parts 44 provided at end parts away from the surface to be polished of the expanding / retracting parts. The plurality of uniform load polishing parts is provided along the surface to be polished, and the hydrostatic pressure supply part can supply uniform hydrostatic pressure to respective hydrostatic pressure applying parts in the plurality of uniform load polishing parts.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polishing machine, and more particularly to a technique suitable for use in polishing free-form surfaces. [Background technology]

[0002] 2. Description of the Related Art In recent years, aspherical optical elements and free-form optical elements have been applied to optical devices in order to improve the optical characteristics of the devices. As a method for polishing a workpiece having such an aspherical surface or a free-form surface, the technique described in Patent Document 1 is known.

[0003] Patent document 1 describes a free-form surface polishing wheel that includes a metal base with a hollow interior that can be filled and sealed with a fluid, and multiple grinding wheel pellets that move in the direction of the rotation axis through multiple holes provided on either the top or bottom surface of the metal base.It also describes that when pressed against a workpiece having a free-form surface, the difference in pressing force on the multiple grinding wheel pellets provided through the multiple holes provided in the metal base is converted into the amount of protrusion, and each grinding wheel pellet can be polished with an equal polishing pressure so as to conform to the free-form surface. Here, the internal pressure generated by pressurizing and sealing the liquid is taken as the polishing load. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 09-066469 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when polishing a free-form surface or aspherical surface using the technology of Patent Document 1, a problem occurs in that a highly accurate surface shape cannot be obtained. Also, the technology of Patent Document 1 has a problem in that the entire surface of the workpiece is not smooth. Furthermore, the technology of Patent Document 1 has a problem in that the surface of the workpiece is scratched.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a polishing machine that can solve the problems of not being able to obtain a high-precision surface shape when polishing a work surface having an aspherical or free-form surface used in optical elements, the problem of not being able to make the entire work surface smooth, and the problem of scratches on the work surface. [Means for solving the problem]

[0007] As a result of extensive research by the present inventors, the causes of the above problems have been revealed as follows. First, regarding the first problem that the technology described in Patent Document 1 cannot obtain a highly accurate surface shape, it was revealed that this is due to the fact that each grinding pellet attached to the polishing tool does not follow the surface during polishing. That is, as shown in Figure 1 of Patent Document 1, it was revealed that a large gap may be created between the grinding pellet surface and the surface to be polished, which causes the polishing load to become non-uniform and deteriorates the shape accuracy.

[0008] Another cause of this problem is that when the surface to be polished is moved during polishing, as in Patent Document 1, all the grinding pellets contract simultaneously when the surface to be polished approaches the metal base, and all the grinding pellets expand simultaneously when the surface to be polished moves away from the metal base. When the grinding pellets expand and contract in this way while the fluid inside the metal base is sealed, the load acting on the surface to be polished from each grinding pellet is the same, but it has become clear that the load acting on the surface to be polished is not the same when all the grinding pellets contract simultaneously and when they expand simultaneously, and this has been found to be one of the causes of deterioration in shape accuracy.

[0009] The second problem, that the entire surface of the workpiece is not smooth when using the technology described in Patent Document 1, is that, as mentioned above, a large gap may sometimes occur between the grinding stone pellet surface and the surface to be polished, making it impossible to polish this gap.It has also become clear that when liquid leaks from the sliding part, that is, when liquid leaks, the leaked liquid may contaminate the polishing liquid, which can have an impact.

[0010] The third problem with the technology described in Patent Document 1, that is, scratches on the workpiece surface, is that grinding is sometimes performed so that the edge of the grinding stone pellet comes into contact with the workpiece surface, as shown in Figure 1 of Patent Document 1, and it has become clear that this edge can cause scratches on the workpiece surface.

[0011] As a means for solving the above problem, the invention described in claim 1 is as follows: A polishing machine capable of polishing a surface to be polished of a workpiece having a free-form surface, a rotation holding unit that holds the workpiece rotatably around a rotation axis; a polishing unit that polishes the surface to be polished; a polishing liquid supply unit that supplies a polishing liquid to the surface to be polished; a hydrostatic pressure supply; and The polishing unit is an extension / retraction portion that is extendable and retractable with respect to the polished surface in a direction substantially parallel to the rotation axis; a polishing pad provided at an end of the extending / retracting portion adjacent to the surface to be polished; a hydrostatic pressure applying unit provided at an end of the extending / retracting unit that is spaced apart from the polishing surface; A plurality of uniform load polishing sections having the same a plurality of the uniform load polishing units are arranged along the surface to be polished so as to be independently drivable, the hydrostatic pressure supply unit is capable of supplying a uniform hydrostatic pressure to each of the hydrostatic pressure application units in the plurality of uniform load polishing units; It is characterized by: The invention described in claim 2 is the grinding machine described in claim 1, The polishing section includes: a surface following portion is provided at an end of the extending / retracting portion that is close to the surface to be polished, the surface following portion supporting the polishing pad so that the inclination angle of the polishing pad can be changed in accordance with the surface to be polished; It is characterized by: The invention described in claim 3 is a grinding machine according to claim 1 or 2, The polishing section includes: a reciprocating support portion is provided that supports the extension / retraction portion so that the extension / retraction portion can be extended and retracted substantially parallel to the rotation axis; It is characterized by: The invention described in claim 4 is a grinding machine according to any one of claims 1 to 3, The hydrostatic pressure application unit is connected to the hydrostatic pressure supply unit via a branch unit. It is characterized by: The invention described in claim 5 is the grinding machine described in claim 4, a cross-sectional area along the flow of pressure fluid in the branching section is larger than a cross-sectional area along the flow of pressure fluid in the hydrostatic pressure application section; It is characterized by: The invention described in claim 6 is the grinding machine described in claim 5, The branching portion also serves as the hydrostatic pressure supply portion. It is characterized by: The invention described in claim 7 is a grinding machine according to any one of claims 1 to 6, the pressure fluid in the hydrostatic pressure application unit and the hydrostatic pressure supply unit contains water; It is characterized by: The invention described in claim 8 is a grinding machine according to any one of claims 1 to 7, The hydrostatic pressure application unit is a cylinder unit that can extend and retract substantially parallel to the rotation axis. It is characterized by: The invention described in claim 9 is a grinding machine according to any one of claims 1 to 7, The hydrostatic pressure application unit is a bellows unit that is extendable and retractable substantially parallel to the rotation axis. It is characterized by:

[0012] According to the invention described in claim 1, The independently drivable uniform load polishing unit allows each polishing pad to extend and retract approximately parallel to the rotation axis relative to the polished surface, which is the free-form surface of the workpiece, and each polishing pad is subjected to uniform hydrostatic pressure by the hydrostatic pressure supply unit and the hydrostatic pressure application unit, making it possible to polish with high precision the free-form surface of a predetermined three-dimensional shape on the workpiece rotated around the rotation axis by the rotating holding unit. At this time, the extension / retraction section restricts the movement of all polishing pads relative to the surface to be polished in the direction of the rotation axis, and uniform hydrostatic pressure is applied to all polishing pads, thereby maintaining the processing accuracy in the polishing process at a specified level. Furthermore, by supporting the polishing pad with the extendable / retractable section and independently arranging the uniform-load polishing sections that apply hydrostatic pressure to the extendable / retractable sections with the hydrostatic pressure applicators, pressure fluctuations in the individual uniform-load polishing sections can be prevented. Furthermore, when applying hydrostatic pressure from the hydrostatic pressure supply section to the hydrostatic pressure applicators, leakage of pressurized fluid that directly reaches the polished surface can be prevented. This prevents contamination of the polishing liquid and maintains the desired processing accuracy during the polishing process. Here, the free-form surface means a curved surface having a complex three-dimensional shape that is difficult to express with a simple mathematical formula, such as a plane or a spherical surface.

[0013] According to the invention described in claim 2, The surface following section supports the polishing pad so that the angle of inclination of the polishing pad relative to the surface to be polished can be adjusted, allowing the polishing pad to move relatively at an angle that follows the free-form surface to be polished during the polishing process. This prevents the polishing pressure of the polishing pad against the surface to be polished from being partially increased or decreased, allowing the processing accuracy to be maintained at a predetermined level during the polishing process.

[0014] According to the invention described in claim 3, Because the extension / retraction sections can be extended and retracted along the rotation axis by the reciprocating support sections and each extension / retraction section can be driven independently, even when a load is applied to the extension / retraction sections in the radial or circumferential direction of the rotation axis due to the rotation of the workpiece, the extension / retraction operation of the extension / retraction sections is not hindered, and the polishing pressure on the polished surface of the polishing pad caused by the operation of the extension / retraction sections does not deviate from a predetermined range, thereby making it possible to maintain a predetermined level of processing accuracy in the polishing process.

[0015] According to the invention described in claim 4, The hydrostatic pressure generated in the hydrostatic pressure supply unit is transmitted to the hydrostatic pressure application unit via the branch unit, allowing each uniform load polishing unit to apply a uniform load independently, thereby maintaining the processing accuracy in the polishing process at a specified level.

[0016] According to the invention described in claim 5, Since the hydrostatic pressure at the branching section can be distributed to the hydrostatic pressure application sections according to the cross-sectional area ratio, each uniform load polishing section can apply a uniform load independently, and the processing accuracy in the polishing process can be maintained at a specified level. Furthermore, by using the branched portion as a pressure accumulator, it is possible to suppress fluctuations in polishing pressure.

[0017] According to the invention described in claim 6, The branching section also serves as a cylinder that acts as a hydrostatic pressure supply section with a larger cross section than the hydrostatic pressure application section, that is, by connecting multiple hydrostatic pressure application sections to a large cross section cylinder, the length along the flow of pressure fluid between the hydrostatic pressure application section and the hydrostatic pressure supply section can be shortened, pressure fluctuations in the hydrostatic pressure application section can be reduced, the pressure controllability of the hydrostatic pressure application section can be improved, and the processing precision in the polishing process can be maintained at a specified level.

[0018] According to the invention described in claim 7, Even if the pressurized fluid contains water and is mixed into the polishing solution, the influence other than the concentration fluctuation of the polishing agent is almost eliminated, and the fluctuation in the polishing state due to the leakage of the pressurized fluid can be reduced, thereby preventing a decrease in the processing accuracy in the polishing process.

[0019] According to the invention described in claim 8, By making each hydrostatic pressure applying section an independent individual cylinder section, it becomes possible to independently drive the extension / retraction sections in the plurality of uniform load polishing sections with the same hydrostatic pressure. According to the invention described in claim 9, By making each hydrostatic pressure applying section an independent individual bellows section, it becomes possible to independently drive the extension / retraction sections in multiple uniform load polishing sections with the same hydrostatic pressure. Also, since the extension / retraction sections can be driven by pressure fluid without a sliding surface, there is no risk of the pressure fluid leaking. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a polishing machine that can obtain a highly accurate surface shape when polishing a work surface having an aspherical or free-form surface used in optical elements, and that can smooth the entire work surface without causing scratches on the work surface. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic cross-sectional view showing a first embodiment of a grinding machine according to the present invention. [Figure 2] FIG. 4 is a schematic cross-sectional view showing a polishing unit in a second embodiment of a polishing machine according to the present invention. [Figure 3] FIG. 10 is a schematic cross-sectional view showing a polishing unit in a third embodiment of a polishing machine according to the present invention. [Figure 4] FIG. 10 is a schematic cross-sectional view showing a polishing unit in a fourth embodiment of a polishing machine according to the present invention. [Figure 5] FIG. 10 is a schematic cross-sectional view showing a polishing unit in a fifth embodiment of a polishing machine according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] A first embodiment of a grinding machine according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a polishing machine according to this embodiment, and in the figure, reference numeral 10 denotes the polishing machine.

[0023] The polishing machine 10 according to this embodiment is a polishing machine capable of polishing a surface W1 to be polished of a workpiece W having a free-form surface. The workpiece W in this embodiment is, for example, optical glass having an aspherical or free-form surface used in optical elements, a crystal material for optical elements, metal, plastic, etc. Therefore, the required processing accuracy is ultimately set to about 10 μm to 0.01 nm, and the surface roughness is set to about 1 μm to 0.01 nm.

[0024] As shown in FIG. 1, the polishing machine 10 according to this embodiment includes a rotation holder 20, a polishing unit 30, a polishing liquid supply unit 25, and a hydrostatic pressure supply unit 50.

[0025] The rotating holder 20 holds the workpiece W so that it can rotate around a rotation axis C. The rotating holder 20 holds the workpiece W on its upper surface. In the drawing, the rotation axis C is shown in the vertical direction, but this configuration is not limited to this, and the rotation axis C may be inclined or may be configured to be along the horizontal direction, or the workpiece W may be held on the lower surface of the rotating holder 20, etc.

[0026] In addition, the rotating holding unit 20 may hold the workpiece W mechanically, or may hold and fix the workpiece W by means of an electrostatic chuck, a vacuum chuck, or adhesive, resin, etc., as long as it can hold the polishing surface W1 of the workpiece W in a manner that allows it to be polished. The rotation holding unit 20 rotates the supported workpiece W about a rotation axis C by a rotation drive source such as a motor (not shown).

[0027] The polishing liquid supply unit 25 has a reservoir tank 26 for storing the polishing liquid. The polishing liquid supply unit 25 supplies the polishing liquid to the surface W1 to be polished. The polishing liquid supply unit 25 has a nozzle 27 for discharging the polishing liquid near the surface W1 to be polished. The polishing liquid may be a liquid solvent containing an abrasive, or, as will be described later, when a polishing pad 43 having fixed abrasive grains is used, the polishing liquid may be pure water or the like.

[0028] The polishing unit 30 polishes the surface W1 to be polished of the workpiece W supported by the rotation holding unit 20. The polishing section 30 includes a plurality of uniform load polishing sections 40. Each of the uniform load polishing sections 40 is supported by a frame 31. Each of the uniform load polishing sections 40 can be driven independently. The uniform load polishing unit 40 includes an extendable portion 41, a mounting portion 42, a polishing pad 43, and a hydrostatic pressure applying portion 44.

[0029] The extension / retraction portion 41 can extend and retract from the surface W1 to be polished substantially parallel to the rotation axis C. The extension / retraction portion 41 is rod-shaped and extends substantially parallel to the rotation axis C. The extension / retraction portion 41 can have a substantially uniform diameter dimension over its entire length in the direction along the rotation axis C. The extension / retraction unit 41 is supported by the grinding unit 30 by a reciprocating support unit 45 so as to be extendable and retractable substantially parallel to the rotation axis C. A plain bearing can be used as the reciprocating support unit 45. For example, a plain bearing made of plastic with good sliding properties or an oil-impregnated type can also be used.

[0030] A mounting portion 42 is attached to the lower end 41a of the extending / retracting portion 41, which is close to the surface to be polished W1, and a polishing pad 43 is provided on the mounting portion 42. The mounting portion 42 and the polishing pad 43 are provided in a state in which the lower end 41a of the extending / retracting portion 41 has an expanded diameter. The mounting portion 42 and the polishing pad 43 have approximately the same diameter. The polishing pad 43 is attached to the entire lower surface of the mounting portion 42. The polishing pad 43 contacts the surface W1 to be polished over a predetermined area. The polishing pad 43 may contain fixed abrasive grains capable of polishing the surface W1 to be polished in accordance with the material and polishing method of the surface W1. Alternatively, the polishing pad 43 may be made of polyurethane foam, suede, nonwoven fabric, or the like.

[0031] The hydrostatic pressure applying unit 44 is provided at an upper end 41b of the extension / retraction unit 41, which is spaced from the polishing surface W1. The hydrostatic pressure applying unit 44 consists of a piston 44a and a cylinder 44b, each having an axis substantially parallel to the rotation axis C. The extension / retraction unit 41 is connected to the lower end of the piston 44a. The cylinder 44b is supported by the frame 31. The cylinder 44b is filled with a pressurized fluid. The cylinder 44b is connected to the branching unit 47 via a connecting portion 44c. The connecting portion 44c communicates with the inside of the cylinder 44b, allowing the pressurized fluid to flow through it. The connecting portion 44c is connected to a connecting portion 47c of the branching unit 47. The hydrostatic pressure applying section 44 and the branching section 47 may be directly connected, or may be connected by a rigid pipe or a flexible pipe such as a hose.

[0032] The branch portion 47 is capable of storing a pressurized fluid therein. The branch portion 47 is sealable. The branch portion 47 is filled with a pressurized fluid. A plurality of connection portions 47c are formed in the branch portion 47. The connection portions 47c communicate with the interior of the branch portion 47, allowing the pressurized fluid to flow therethrough. The branch portion 47 is connected to a plurality of hydrostatic pressure application portions 44, allowing the pressurized fluid to flow in and out so as to generate a uniform hydrostatic pressure in the hydrostatic pressure application portions 44.

[0033] The branch portion 47 is connected to a hydrostatic pressure supply portion 50 via a connection portion 47b.

[0034] The hydrostatic pressure supply unit 50 generates hydrostatic pressure that is transmitted to the hydrostatic pressure application unit 44. The hydrostatic pressure supply unit 50 is made up of a piston 51a and a cylinder 51b, each having an axis that is substantially parallel to the vertical direction. A weight 52 for generating hydrostatic pressure is placed on the piston 51a. The cylinder 51b is connected to the connection portion 47b of the branch portion 47. The cylinder 51b is filled with pressurized fluid.

[0035] In the hydrostatic pressure supply unit 50, a predetermined hydrostatic pressure is generated inside the cylinder 51b by the piston 51a pressed by the weight of the weight 52. The hydrostatic pressure generated in the hydrostatic pressure supply unit 50 is transmitted to the hydrostatic pressure application unit 44 via the pressurized fluid passing through the branching portion 47. The hydrostatic pressure supply unit 50 may have other configurations, such as a hydrostatic pressure generating pump or a pressure pump, as long as it is capable of generating a predetermined hydrostatic pressure.

[0036] The plurality of uniform load polishing units 40 are arranged such that the polishing pads 43 are aligned in a predetermined direction along the surface W1 to be polished so that all necessary areas of the surface W1 to be polished can be polished when the workpiece W is rotated. The plurality of uniform load polishing units 40 are aligned parallel to one another along the rotation axis C. The plurality of uniform load polishing units 40 are extendable and retractable in the same direction, and can apply polishing pressure in parallel directions.

[0037] According to the polishing machine 10 of this embodiment, the hydrostatic pressure generated in the hydrostatic pressure supply unit 50 is transmitted as uniform hydrostatic pressure by the branching unit 47 to the multiple hydrostatic pressure application units 44. Therefore, the multiple uniform load polishing units 40 press their respective extension / retraction units 41 toward the polished surface W1 with the same hydrostatic pressure. With the workpiece W supported by the rotary holder 20 and rotating around the rotation axis C, a polishing liquid is supplied from the polishing liquid supply unit 25 to the polished surface W1.

[0038] In this state, the polishing pad 43 pressed by the extending / retracting portion 41 moves while contacting the surface W1 to be polished, and as a result, the amount of protrusion of the extending / retracting portion 41 changes in accordance with the three-dimensional shape of the surface W1 to be polished at each of the uniform load polishing units 40. The uniform load polishing units 40 polish the surface W1 to follow its three-dimensional shape using the same hydrostatic pressure.

[0039] At this time, the hydrostatic pressure supply unit 50 is capable of supplying uniform hydrostatic pressure to each of the hydrostatic pressure application units 44 in the plurality of uniform load polishing units 40. Moreover, since the plurality of uniform load polishing units 40 are arranged along the surface to be polished W1 so as to be able to be driven independently, the polishing pads 43 in each of the uniform load polishing units 40 can polish the surface to be polished W1 at the same polishing pressure, following the three-dimensional shape of the surface to be polished W1.

[0040] It is also possible to change the polishing pressure generated by the hydrostatic pressure supply unit 50 during the polishing process. Specifically, the polishing pressure generated by the hydrostatic pressure supply unit 50 can be set to a high pressure in the early stage of the polishing process to increase the removal rate, and to a low pressure in the final stage of the polishing process, thereby changing the polishing pressure over time in the polishing process. In this case, the hydrostatic pressures in the individual uniform load polishing units 40 are changed simultaneously as the polishing process progresses.

[0041] Furthermore, when using a fixed abrasive polishing pad 43 and pure water as the polishing liquid, water (pure water) can be used as the pressure fluid in the hydrostatic pressure applying unit 44 and the hydrostatic pressure supply unit 50. In this case, liquid leakage from the hydrostatic pressure applying unit 44 can be actively utilized to constantly supply the polishing liquid to the polishing area.

[0042] According to this embodiment, in the plurality of independently drivable uniform load polishing units 40, each polishing pad 43 can be extended and retracted approximately parallel to the rotation axis C relative to the polished surface W1, which is a free-form surface of the workpiece W, and a uniform hydrostatic pressure is applied to each polishing pad 43 by the hydrostatic pressure supply unit 50 and the hydrostatic pressure application unit 44. This makes it possible to polish a free-form surface having a predetermined three-dimensional shape with high precision on the workpiece W rotated about the rotation axis C by the rotary holder 20. The extension and retraction units 41 restrict the movement of all polishing pads 43 relative to the polished surface W1 in the direction along the rotation axis C, and the application of a uniform hydrostatic pressure makes it possible to maintain a predetermined processing precision in the polishing process.

[0043] Furthermore, the polishing pad 43 is supported by the extension / retraction section 41, and multiple uniform load polishing sections 40 are independently arranged to apply hydrostatic pressure to the extension / retraction section 41 using the hydrostatic pressure application section 44. This prevents leakage of pressurized fluid and direct contact with the polished surface W1 when applying hydrostatic pressure from the hydrostatic pressure supply section 50 to the hydrostatic pressure application section 44. This prevents contamination of the polishing liquid and maintains a predetermined processing accuracy in the polishing process. The hydrostatic pressure generated in the hydrostatic pressure supply unit 50 is transmitted to the hydrostatic pressure application unit 44 via the branch unit 47, so that each uniform load polishing unit 40 can apply a uniform load independently, thereby maintaining the processing accuracy in the polishing process at a predetermined level.

[0044] According to this embodiment, it is possible to improve the uniformity of the pressure applied by the polishing pad 43 to the polished surface W1 of a workpiece having an aspherical or free-form surface used in optical elements, improve the smoothness of the polished surface W1, suppress the effect of contamination on the polishing liquid, and improve the polishing processing accuracy.

[0045] A second embodiment of a grinding machine according to the present invention will be described below with reference to the drawings. FIG. 2 is a schematic cross-sectional view showing the polishing section of the polishing machine in this embodiment. The difference between this embodiment and the first embodiment described above is the surface following section 46. Other components corresponding to those in the first embodiment described above are given the same reference numerals and will not be described again.

[0046] As shown in Fig. 2, the grinding machine 10 in this embodiment has a surface following section 46. The surface following section 46 is provided at the lower end section 41a of the extension / retraction section 41, which is close to the surface W1 to be ground. The surface following section 46 supports the mounting section 42 relative to the lower end section 41a of the extension / retraction section 41 so that the inclination angle of the mounting section 42 can be changed. The surface following section 46 connects the lower end section 41a and the mounting section 42 as a so-called universal joint. Specifically, the surface conforming portion 46 is composed of a spherical joint portion provided at the lower end 41a of the extending / retracting portion 41 and a recessed portion provided in the mounting portion 42 into which the joint portion is fitted. The surface conforming portion 46 supports the polishing pad 43 so that the inclination angle can be changed to conform to the surface W1 to be polished.

[0047] According to this embodiment, as described in the first embodiment, the plurality of polishing pads 43 pressed against the polished surface W1 with a uniform hydrostatic pressure can be moved relatively at a contact angle that follows the polished surface W1 by the surface following portion 46. This prevents the polishing pressure of the polishing pads 43 on the polished surface W1 from being partially increased or decreased, and therefore the processing accuracy in the polishing process can be maintained at a predetermined level.

[0048] In this embodiment, the same effects as those of the above-described embodiment can be achieved.

[0049] A third embodiment of a grinding machine according to the present invention will be described below with reference to the drawings. FIG. 3 is a schematic cross-sectional view showing the polishing unit of the polishing machine according to this embodiment. This embodiment differs from the first and second embodiments in terms of the reciprocating support section, and the other corresponding components are given the same reference numerals and descriptions thereof will be omitted.

[0050] 3, the reciprocating support unit 45 in this embodiment includes a ball bushing 45a. The ball bushing 45a facilitates the reciprocating movement of the extension / retraction unit 41 along the rotation axis C, and also restricts the position of the extension / retraction unit 41 so that it does not move in the lateral direction perpendicular to the rotation axis C.

[0051] In this embodiment, the retractable portion 41 can extend and retract by the reciprocating support portion 45 equipped with the ball bushing 45a, with the movement direction restricted only to the direction along the rotation axis C. Therefore, even if a load is applied to the extension / retractable portion 41 in the radial or circumferential direction of the rotation axis C due to the rotation of the workpiece W or the like, the extension / retractable portion 41, which can be driven independently, will not be hindered from extending and retracting.

[0052] Therefore, the polishing pressure applied to the polished surface W1 of the polishing pad 43 by the reciprocating movement of the extending / retracting portion 41 does not deviate from a predetermined range, and therefore the processing accuracy in the polishing process can be maintained at a predetermined level.

[0053] In this embodiment, the same effects as those of the above-described embodiment can be achieved.

[0054] A fourth embodiment of the grinding machine according to the present invention will be described below with reference to the drawings. FIG. 4 is a schematic cross-sectional view showing the polishing unit of the polishing machine according to this embodiment. This embodiment differs from the first to third embodiments described above in terms of the hydrostatic pressure applying section, and the other corresponding components are given the same reference numerals and descriptions thereof will be omitted.

[0055] The hydrostatic pressure applicator 44 in this embodiment includes a bellows portion 44e. The bellows portion 44e is sandwiched between a lower connecting portion 44g formed on the upper end portion 41b of the extendable portion 41, which is spaced from the polishing surface W1, and an upper connecting portion 44f connected to the connecting portion 44c. The lower connecting portion 44g and the upper connecting portion 44f can have substantially the same diameter as the cylinder 44b in the above-described embodiment.

[0056] The bellows portion 44e is supported by the frame 31 via the upper connecting portion 44f. The bellows portion 44e is filled with a pressurized fluid. The bellows portion 44e is connected to the branching portion 47 via the connecting portion 44c. The bellows portion 44e is expandable and contractable along an axis that is approximately parallel to the vertical direction.

[0057] According to the grinding machine 10 of this embodiment, the hydrostatic pressure generated in the hydrostatic pressure supply unit 50 is transmitted as uniform hydrostatic pressure by the branching unit 47 to the multiple hydrostatic pressure application units 44. This hydrostatic pressure causes the bellows unit 44e to expand and contract along the direction of the rotation axis C. This allows the extension / retraction unit 41 connected to the lower connection unit 44g to perform extension / retraction motion.

[0058] In this embodiment, the same effects as those of the above-described embodiment can be achieved.

[0059] A fifth embodiment of a grinding machine according to the present invention will be described below with reference to the drawings. FIG. 5 is a schematic cross-sectional view showing the polishing unit of the polishing machine in this embodiment. This embodiment differs from the first to fourth embodiments described above in terms of the hydrostatic pressure supply unit, and the other corresponding components are given the same reference numerals and descriptions thereof will be omitted.

[0060] The hydrostatic pressure supply unit 50 in this embodiment also serves as the branching unit 47. That is, in this embodiment, the branching unit 47 also serves as the hydrostatic pressure supply unit 50. Branching portion 47 is configured as cylinder 51d in hydrostatic pressure supplying portion 50, and its upper opening is closed by piston 52d. Cylinder 51d has a plurality of connecting portions 47c formed on its lower side. Piston 52d pressurizes the inside of branching portion 47 with its weight, similar to weight 52 in hydrostatic pressure supplying portion 50.

[0061] In this embodiment, the branching portion 47, which also serves as the cylinder 51d, can act as a pressure accumulator. Moreover, because the branching portion 47 and the hydrostatic pressure supplying portion 50 can be integrated and used together, the number of parts can be reduced, and with a simple configuration, a predetermined hydrostatic pressure can be stably supplied to the plurality of hydrostatic pressure applying portions 44. Furthermore, because the length of the flow path for the pressure fluid between the branching portion 47 and the hydrostatic pressure supplying portion 50 can be eliminated, fluctuations in hydrostatic pressure can be reduced, and the stability of the polishing process can be improved.

[0062] In this embodiment, the same effects as those of the above-described embodiment can be achieved.

[0063] In the present invention, the configurations in the above-described embodiments may be individually selected and appropriately combined to form a configuration.

[0064] According to the present invention, it is possible to provide a polishing machine that can improve the uniformity of polishing pressure on a work surface having an aspherical or free-form surface used in optical elements, improve the smoothness of the work surface, suppress the effect of contamination on the polishing liquid, and improve processing accuracy. [Explanation of symbols]

[0065] 10...Polishing machine 20...Rotation holding part 25...Polishing liquid supply section 30...Polishing section 40...Uniform load polishing section 41...Extendable part 42...Mounting part 43...Polishing pad 44...Hydrostatic pressure application section 44a...Piston 44b...cylinder 44e...Bellows section 45...Reciprocating support part 45a...ball bushing 46...Face tracking section 47...Branch 50...Hydrostatic pressure supply section 51a, 52d...Piston 51b, 51d...Cylinder 52... Weight C...Rotation axis W…Work W1…Surface to be polished

Claims

1. A polishing machine capable of polishing a surface to be polished of a workpiece having a free-form surface, a rotation holding unit that holds the workpiece rotatably around a rotation axis; a polishing unit that polishes the surface to be polished; a polishing liquid supply unit that supplies a polishing liquid to the surface to be polished; a hydrostatic pressure supply unit that generates hydrostatic pressure; and the polishing unit includes a frame, a plurality of uniform load polishing units supported by the frame, and a reciprocating support unit; a plurality of the uniform load polishing units are arranged along the surface to be polished so as to be independently drivable, Each of the plurality of uniform load polishing units is an extension / retraction portion that is extendable and retractable with respect to the polished surface in a direction substantially parallel to the rotation axis; a polishing pad provided at an end of the extending / retracting portion adjacent to the surface to be polished; a hydrostatic pressure applying unit provided at an end of the extending / retracting unit that is spaced apart from the polishing surface; a reciprocating support unit that supports the extension / retraction unit on the frame while restricting the movement direction of the extension / retraction unit only in the direction along the rotation axis; and the extension / retraction portion is supported by the frame by the reciprocating support portion so as to be extendable and retractable substantially parallel to the rotation axis; the pressure fluid in the hydrostatic pressure application unit and the hydrostatic pressure supply unit contains water; a plurality of the hydrostatic pressure application units are connected to a branch unit via a connecting pipe unit; the hydrostatic pressure supply unit connected to the branch unit is capable of supplying uniform hydrostatic pressure to each of the hydrostatic pressure application units in the plurality of uniform load polishing units; A grinding machine characterized by:

2. The polishing section includes: a surface following portion is provided at an end of the extending / retracting portion that is close to the surface to be polished, the surface following portion supporting the polishing pad so that the inclination angle of the polishing pad can be changed in accordance with the surface to be polished; 2. The polishing machine according to claim 1.

3. The hydrostatic pressure application unit is connected to the hydrostatic pressure supply unit via a branch unit.

3. The grinding machine according to claim 1 or 2.

4. a cross-sectional area along the flow of pressure fluid in the branching section is larger than a cross-sectional area along the flow of pressure fluid in the hydrostatic pressure application section; 4. The polishing machine according to claim 3.

5. The reciprocating support portion is a slide bearing or a ball bushing.

2. The polishing machine according to claim 1.

6. The hydrostatic pressure application unit is a cylinder unit that can extend and retract substantially parallel to the rotation axis.

6. The grinding machine according to claim 1, wherein the grinding machine is a grinding machine having a grinding head.

7. The hydrostatic pressure application unit is a bellows unit that is extendable and retractable substantially parallel to the rotation axis.

6. The grinding machine according to claim 1, wherein the grinding machine is a grinding machine having a grinding head.

8. A polishing machine capable of polishing a surface to be polished of a workpiece having a free-form surface, a rotation holding unit that holds the workpiece rotatably around a rotation axis; a polishing unit that polishes the surface to be polished; a polishing liquid supply unit that supplies a polishing liquid to the surface to be polished; a hydrostatic pressure supply unit that generates hydrostatic pressure; and the polishing unit includes a frame, a plurality of uniform load polishing units supported by the frame, and a reciprocating support unit; a plurality of the uniform load polishing units are arranged along the surface to be polished so as to be independently drivable, Each of the plurality of uniform load polishing units is an extension / retraction portion that is extendable and retractable with respect to the polished surface in a direction substantially parallel to the rotation axis; a polishing pad provided at an end of the extending / retracting portion adjacent to the surface to be polished; a hydrostatic pressure applying unit provided at an end of the extending / retracting unit that is spaced apart from the polishing surface; a reciprocating support unit that supports the extension / retraction unit on the frame while restricting the movement direction of the extension / retraction unit only in the direction along the rotation axis; and the extension / retraction portion is supported by the frame by the reciprocating support portion so as to be extendable and retractable substantially parallel to the rotation axis; the pressure fluid in the hydrostatic pressure application unit and the hydrostatic pressure supply unit contains water; a plurality of the hydrostatic pressure application units are connected to a branch unit via a connecting pipe unit; The branching portion also serves as the hydrostatic pressure supply portion, the hydrostatic pressure supply unit is capable of supplying a uniform hydrostatic pressure to each of the hydrostatic pressure application units in the plurality of uniform load polishing units; A grinding machine characterized by:

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