JPH05177535A - Method and device for polishing - Google Patents

Abstract

PURPOSE:To supply the processing liquid uniformly while thermal deformation of a holder is suppressed, by immersing a work to be processed and a polisher completely in a processing solution, and supplying the solution having passed through the polisher to the work from the opposed face side of the polisher. CONSTITUTION:A polishing device is chiefly composed of a work holding part 2 which holds a work to be processed 1 and rotates it, a polisher holding part 4 which presses polisher 3 to the work 1 and rotates the polisher in reversals by a swing driving part 13, and a processing solution supply part 6 to supply a processing solution 5 to the part of processing. The processing solution 5 is interposed between the work 1 and polisher 3 and they are moved in relative motions, and thereby polishing is performed in the condition being contacted. At this time, the work 1 and polisher 3 are immersed completely in the processing solution 5 contained in a processing trough 7. The solution 5 having passed through the polisher 3 is supplied to the work 1 from the opposed face side of the polisher 3 to the work 1.

Description

Detailed Description of the Invention

 [Object of the Invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method and apparatus capable of achieving non-contact polishing with high shape accuracy.

[0002]

2. Description of the Related Art Recently, in the field of ultra-precision machining, a non-contact polishing process called float polishing has become popular as disclosed in, for example, JP-A-63-180463. In this float polishing, as shown in FIG. 6, a polishing plate B and a workpiece C, which are eccentric for a certain distance, are simultaneously rotated in a working fluid A prepared by suspending fine powder particles of several tens of angstroms in distilled water. It is a thing. At this time, if the workpiece C is allowed to float freely and only the rotational torque is transmitted, a slight gap is created between the workpiece C and the polishing plate B due to the dynamic pressure effect, and the workpiece C C rises. Then, the actual processing proceeds due to the fine destruction due to the collision of the fine powder particles passing through the gap with the workpiece C.

The characteristics of the conventional non-contact polishing process are as follows. That is, (1) the working liquid A in the working tank D is such that the surface of the workpiece C is immersed. (2) The working fluid A was supplied to the surface of the workpiece C from the working fluid discharge hose E located several cm above the vicinity of the central portion of the polishing plate B. (3) The holder F holding the workpiece C was driven to rotate by force through the pin joint G.

However, the conventional non-contact polishing process has the following drawbacks. <1> Since the temperature of the holder F holding the workpiece C is not controlled, thermal deformation occurs during machining, and the workpiece C is also deformed accordingly. It is an obstacle. <2> Since the machining liquid A is supplied from the outer peripheral portion of the workpiece C toward the center, it becomes difficult to uniformly machine the entire surface of the workpiece. <3> Since the work piece C is held only by the pin joint G, the work piece C is often in an unstable state during working, so that the work piece C and the polishing plate B come into contact with each other. In some cases, the workpiece C may be damaged. Further, since the holding of the work piece C is unstable, the movement of the work piece C is only the forced rotation movement and cannot be combined with the swing movement. As a result, the workpiece C has to draw the same locus with respect to the polishing plate B, which is an obstacle to improving the shape accuracy of the workpiece C.

[0005]

As described above, the conventional non-contact polishing process causes thermal deformation of the work piece, non-uniformity of supply of the working fluid, and swing motion of the work piece which is forced to rotate. Have the problem that they cannot be combined.

The present invention has been made in consideration of the above circumstances, and supplies the working liquid uniformly to the surface of the workpiece while suppressing thermal deformation of the holder holding the workpiece, and By rotating and swinging the holder,
It is an object of the present invention to provide a polishing method and a polishing apparatus capable of realizing ultra-precision polishing processing without contact. [Constitution of Invention]

[0007]

SUMMARY OF THE INVENTION According to the present invention, a polisher and a work piece are completely immersed in a working fluid, and the working fluid is worked with the polisher through an opening provided in a polishing action surface of the polisher. Direct injection into the gap between the object and
In the state where the polisher is pressed relatively to the work piece, the polisher and the work piece are rotationally driven and relatively rocked.

[0008]

According to the present invention as described above, the thermal deformation of the polisher and the work piece during processing can be suppressed, and a uniform working liquid film can be stably interposed in the gap between the polisher and the work piece. As a result, it becomes possible to move the polisher in a manner that faithfully follows the work piece and stably, and as a result, the surface roughness and shape accuracy of the work piece can be dramatically improved. it can.

[0009]

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a polishing apparatus of this embodiment. This polishing apparatus includes a workpiece holder 2 for holding and rotating the workpiece 1, and a polisher 3 provided above the workpiece holder 2 for holding the workpiece 3 on the workpiece holder 2. It comprises a polisher holding portion 4 that presses against the held work piece 1 and rotates / rocks the polisher 3, and a working liquid supply portion 6 that supplies a working liquid 5 to a working portion. The workpiece holder 2 has a bottomed cylindrical processing tank 7, a base 8 for supporting the processing tank 7, and a base 8 for supporting the processing tank 7.
And a motor 9 for driving the processing tank 7 to rotate around its axis. A disk-shaped workpiece 1 such as a concave spherical mirror is coaxially fixed to the inner bottom of the processing tank 7 via a jig (not shown). On the other hand, the polisher holder 4 has a convex spherical surface 1 on one main surface.
A disk-shaped polisher 3 made of, for example, tin and formed in 0, and a rotation transmitting portion 11 which is coaxially connected to the other main surface of the polisher 3 and which transmits a rotation torque to the polisher 3 so as to be vertically movable within a certain range. And a polisher pressurizing section 3a which is provided adjacent to the rotation transmitting section 11 and presses the polisher 3 rotating through the rotation transmitting section 11 against the work piece 1, and the rotation transmitting section 11 1 to rotate the polisher 3 and to rotate the polisher 3, a swing drive unit 13 on which the rotary drive unit 12 is mounted and swings in the directions of arrows X1 and X2 in FIG. It comprises a bridging portion 14 that holds the workpiece holder 2 so as to straddle it. Therefore, the polisher 3 has an outer diameter that is ¼ or less of the outer diameter of the workpiece 1, and as shown in FIGS. 2 and 3, the disk-shaped main body 15
And the convex spherical surface 1 formed on one main surface of the main body portion 15.
0, a spiral groove 11 (only the cross-sectional shape is shown in the drawing) formed on the convex spherical surface 10, and one end openings 16 and 16 provided inside the main body portion 15 and the main body portion 15. , Which is provided near the center of the other main surface of the other end 17 and is provided on the convex spherical surface 10 and introduced through the openings 16 and 16.
And a machining liquid guide hole 18 for ejecting the liquid from the opening 17 to the outside. And the opening 1 of the machining fluid guide hole 18
Reference numerals 6 and 16 are provided at two symmetrical positions on the other main surface of the main body 15. Further, the polisher 3 has a circular concave portion 19 formed in the central portion of the convex spherical surface 10 and four linear grooves 20 ... There is. The openings 17 ... Of the machining liquid guide holes 18 are arranged at equal intervals in the radial direction inside the linear grooves 20. On the other hand, the rotation transmission unit 11
As shown in FIG. 4, a first rotary shaft 21 coaxially connected to the other main surface of the polisher 3, a constant velocity ball joint 22 coupled to the first rotary shaft 21, and a constant velocity ball joint 22 The second rotary shaft 23 is connected to the first rotary shaft 21 and a bearing 24 that supports the second rotary shaft 23. The constant velocity ball joint 22 is, as shown in FIG.
1 and the ring body 25 fitted to the tip of the ring body 2
5, a joint space 26 is formed to surround the joint space 26, and the opposite side of the joint space 26 is coaxially connected to the second rotating shaft 23, and the inner surface of the joint space 27 and the outer surface of the ring body 25 are engraved. ., 29. The steel balls 30 are rotatably interposed in the axial grooves 28, 29. The groove 28 ...
For example, each of 29 ... Is engraved. Two steel balls 30, 3 facing each other of these steel balls 30.
The line that connects the centers of 0 passes through the intersection of the axes of the first rotating shaft 21 and the second rotating shaft 23 that are connected to each other, and is provided in a structure that is present in a plane perpendicular to the paper surface. The first rotating shaft 21 is movable in the Z direction within the range of the length of the grooves 28 through the steel balls 30 and is rotatable in all directions around the intersection. There is. Further, the bridge portion 14 is composed of bridge piers 32 and 32 erected on both sides of the upper portion of the base 8 along the sides thereof so as to be positionally adjustable, and a bridge body 33 erected on these piers 32 and 32. ing.
The swing drive unit 13 includes a swing table unit 34 fixed on the bridge body 33, and a drive unit 35 also fixed on the bridge body 33 adjacent to the swing table unit 34. .. The swing table section 34 is, for example, a high-precision table such as a cross roller table, and includes a base body 36 fixedly provided on the bridge body 33, and the base body 36 that swings in the directions of arrows X1 and X2. The table 37 is movably mounted. Further, in detail, the drive unit 35 is connected between the motor 13a, the cam mechanism 13b rotationally driven by the motor 13a, the cam mechanism 13b and the table body 37, and rotates the cam mechanism 13b. Connecting rod 3 for converting into swinging motion in the directions of arrows X1 and X2
It consists of 8. Further, the rotation drive unit 12 is shown in FIG.
As shown in FIG. 3, the mounting column 3 fixedly mounted on the table body 37
9, a support arm 40 having one end fixed to the mounting post 39 and the other end connected to the bearing 24 to support the rotation transmission part 11 and the polisher 3 in a cantilevered manner, and the second rotation shaft 23 described above. A first pulley 41 fitted to an end portion, a motor 42 fixed to a mounting post 39, a second pulley 43 fitted to a rotation shaft of this motor 42, a first pulley 40 and a first pulley 40. Two
The belt 44 is wound around the pulleys 43 of FIG. The support arm portion 40 is provided so that the mounting position in the Z direction with respect to the mounting column 39 can be adjusted. Further, the polisher pressurizing unit 3 a includes the bearing 24 of the rotation transmitting unit 11.
A holding body 45 integrally connected to and fixed to the holding body 45, a pressing shaft 46 having an upper end portion fitted in a holding hole 46 provided at a lower portion of the holding body 45 so as to be freely inserted and removed, and the pressing shaft 46. Sphere seat 47 attached to the lower end of the sphere, a pressurizing sphere 48 rotatably attached to the sphere seat 47, and a pressurizing shaft 46 loaded in the holding hole 46 and elastically moving the pressurizing shaft 46 to the pressurizing sphere 48 side. And a spring 49 for urging the target. On the other hand, the machining fluid supply unit 6 forcibly circulates the machining fluid 5 and controls the machining fluid 5 at a constant temperature, and the machining fluid that guides the machining fluid 5 to the openings 16 and 16 of the polisher 3. Guide 51
And a working liquid stirring section 52 for stirring the working liquid 5 accumulated in the working tank 7. The machining fluid controller 50 includes a pump (not shown) forcibly circulating the machining fluid 5 and a thermostat (heater and cooler) for maintaining and controlling the machining fluid 5 at a constant temperature of, for example, 22 ± 0.1 ° C. ) And have. Further, the machining fluid guide portion 51 is a rotary coupling 53 attached to the upper end portion of the second rotary shaft 23, and a machining fluid supply for introducing the machining fluid 5 from the machining fluid controller 50 side via the rotary coupling 53. A working fluid introduction hole that is directly connected to the hose 53a and the rotary coupling 53, is bored along the axis from the upper end of the second rotary shaft 23 to the middle, and is open at the outer peripheral surface of the central part of the second rotary shaft 23. 54, a machining fluid guide hose 55, 55 having one end connected to the side portion of the bearing 24 and the other end connected to the openings 16, 16 of the polisher 3, and the machining fluid 5 in the machining tank 7 And a working fluid recovery hose 55a to be recovered in 50. On the other hand, the working fluid agitator 52
Is a supporting jig 56 fixed to the side plate of the processing tank 7, a motor 57 supported by the supporting jig 56, and a motor 5
The stirring fan 58 is connected to the rotary shaft of No. 7 and is immersed in the working fluid 5 to stir the working fluid 5. Next, the polishing method of the present invention using the polishing apparatus having the above structure will be described.

First, the workpiece 1 is coaxially fixed to the inner bottom of the processing tank 7 of the workpiece holder 2 via a jig (not shown). This work piece 1 has a concave spherical surface 1a which is previously polished.
(See FIG. 4) are formed. Next, the bridging portion 14 positions the polisher 3 in the Y direction (direction perpendicular to the paper surface of FIG. 1) so that the polisher 3 is positioned substantially at the center of the workpiece 1 in the radial direction. Then, the support arm portion 40 is moved to Z
And is fixed at a position where the polisher 3 abuts the workpiece 1. Then, the machining fluid 5 is replaced with the machining fluid 5
Is supplied to the processing tank 7 until the polisher 3 is completely immersed. The working liquid 5 is a suspension of abrasive grains composed of fine powder particles of several tens of angstroms in distilled water. Then, the motor 9 is started to move the workpiece 1 to the arrow θ.
For example, it is rotated at 50 rpm in one direction. At the same time, the motor 42 of the rotary drive unit 12 is activated to rotate the polisher 3 in the direction of the arrow θ2 at, for example, 55 revolutions per minute. That is, the rotation of the motor 42 depends on the rotation of the second pulley 43 and the belt 4.
4, transmitted to the second rotary shaft 23 via the first pulley 40. Then, the rotation of the second rotating shaft 23 is transmitted to the polisher 3 connected to the first rotating shaft 21 via the constant velocity ball joint 22. Further, in conjunction with the rotational movement of the polisher 3, the swing drive unit 13 is activated to swing the polisher 3 in the directions of the arrows X1 and X2 at, for example, 10 reciprocations per minute. That is, when the motor 13a of the swing drive unit 13 is started, the connecting rod 38 swings in the directions of arrows X1 and X2 by the operation of the cam mechanism 13b. As a result, the table body 37
The rotation drive unit 12 fixed on the top also swings in the directions of arrows X1 and X2, and the polisher 3 rotates on the workpiece 1 in the direction of arrow θ2 and swings in the directions of arrows X1 and X2. At this time, the polisher 3 is pressed against the workpiece 1 via the pressing ball 48 by the elastic biasing force of the spring 49. By this and the polisher 3 being connected to the second rotary shaft 23 via the constant velocity ball joint 22, the polisher 3 is
It moves faithfully following the concave spherical surface 1a. On the other hand, by activating the machining fluid controller 50, the machining fluid 5 is introduced into the machining fluid introduction hole 54 via the machining fluid supply hose 53a. The machining fluid 5 introduced into the machining fluid introduction hole 54 is guided to the machining fluid guide hole 18 of the polisher 3 via the machining fluid guide hoses 55, 55. Then, the machining fluid 5 introduced into the machining fluid guide hole 18 is sprayed from the openings 17 ... into the gap between the polisher 3 and the workpiece 1. As a result, the machining liquid 5 spreads from the central portion of the polisher 3 toward the outer peripheral portion thereof due to the centrifugal force caused by the rotation of the polisher 3,
Since a uniform liquid film of, for example, about μm always exists between the workpiece 1 and the workpiece 1, the polisher 3 is always in a stable floating state above the workpiece 1, and the workpiece 1 Is finely broken by collision of the abrasive grains suspended in the working liquid 5, and is polished with an extremely high precision. The fact that the polisher 3 is always in a stable floating state above the workpiece 1 also helps prevent damage such as scratches due to direct collision of the polisher 3 of the workpiece 1. Further, at this time, the working fluid 5 in the working tank 7 is treated by the working fluid stirring unit 52.
Stir by. Accordingly, it is possible to prevent the abrasive grains from precipitating in the processing tank 7 and disperse the abrasive particles in the processing tank 7. Furthermore, the temperature of the machining fluid 5 is controlled by the machining fluid controller 50, the polisher 3 and the workpiece 1 are completely immersed in the machining fluid 5, and the machining fluid 5 is processed by the polisher 3. This is combined with the fact that the liquid is directly injected into the gap between the polisher 3 and the workpiece 1 through the openings 17 of the liquid guide hole 18, so that thermal deformation of the polisher 3 and the workpiece 1 is suppressed. be able to. Then, the polisher 3 is rotationally driven in the direction of the arrow θ2 by the rotary drive unit 12 having the constant velocity ball joint 22 while being pressed against the workpiece 1 by the polisher pressurizing unit 3a, and also the swing drive is performed. Since the portion 13 is swingably driven in the directions of the arrows X1 and X2, the convex spherical surface 10 of the polisher 3 in which the spiral groove 11 is formed faithfully follows the concave spherical surface 1a of the workpiece 1 and is stably moved. Can be made Thus, according to the polishing method of this embodiment, the concave spherical surface 1a of the workpiece 1 is
Can be improved from a surface roughness of 0.1 μmRa to a surface roughness of 1 angstrom Ra, and a shape accuracy of 0.3 μmP-V to a surface roughness of 0.06 μmRa.

As described above, according to the polishing method and the apparatus thereof of this embodiment, <1> the machining fluid 5 is fed to the machining fluid controller 50.
The temperature is controlled to a constant temperature with the polisher 3 and the workpiece 1 is completely immersed in the machining fluid 5, and the machining fluid 5 is passed through the openings 17 of the machining fluid guide holes 18 of the polisher 3 ... By directly injecting into the gap between the workpiece 3 and the workpiece 1, thermal deformation during polishing of the polisher 3 and the workpiece 1 can be suppressed. <2> The machining liquid 5 is directly jetted into the gap between the polisher 3 and the workpiece 1 through the openings 17 of the machining liquid guide hole 18 of the polisher 3, and the machining liquid 5 in the machining tank 7 is injected. Stirring by the machining liquid agitator 52 to promote the dispersion of the abrasive grains in the machining tank 7, so that a uniform machining liquid film can be stably present in the gap between the polisher 3 and the workpiece 1. Is now possible. <3> While the polisher 3 is pressed against the workpiece 1 by the polisher pressurizing unit 3a, the rotary drive unit 12 having the constant velocity ball joint 22 rotationally drives it in the direction of the arrow θ2, and the swing drive unit 13 drives the arrow X1. , X2 direction, so that the convex spherical surface 10 of the polisher 3 in which the spiral groove 11 is formed can be moved in a stable manner by faithfully following the concave spherical surface 1a of the workpiece 1. , The above
Combined with the effects of 1> and <2>, the concave spherical surface 1a of the workpiece 1 has a surface roughness of 0.1 μmRa to a surface roughness of 1 angstrom Ra, and a surface accuracy of 0.3 μmP-V. The roughness can be improved to 0.06 μm PV.

In the above embodiment, the workpiece 1
Although the lower part and the polisher 3 are arranged above, the workpiece 1 may be arranged above and the polisher 3 may be arranged below. In this case, the polisher 3 is driven to rotate, and the workpiece 1 side is driven to rotate and swing. In short, the swing drive may be relative. Further, in this case, the constant velocity ball joint 22 may be provided on either the rotating shaft on the side of the workpiece 1 or the rotating shaft on the side of the polisher 3, and when the surface to be processed of the workpiece 1 is a flat surface, The constant velocity ball joint 22 may be omitted. Further, the polisher pressurizing unit 3a
Although the spring 49 is used as the elastic biasing source of the above, a magnet may be adopted.

[0014]

According to the present invention, the polisher and the work piece are completely immersed in the working fluid, and the working fluid is allowed to leave a gap between the polisher and the work piece through an opening provided on the polishing surface of the polisher. By directly injecting into the nozzle, thermal deformation during machining of the polisher and the workpiece can be suppressed, and a uniform machining liquid film can be stably interposed in the gap between the polisher and the workpiece. Will be able to. Furthermore, while the polisher is pressed against the work piece by the pressing portion, the polisher and the work piece are rotationally driven, and the polisher is rockably driven relative to the work piece. Therefore, it becomes possible to move the polisher in a manner that faithfully follows the work piece and stably, and in combination with the above-mentioned effects, the surface roughness and shape accuracy of the work piece are dramatically improved. Can be improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a polishing apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view of a polisher of a polishing apparatus according to an embodiment of the present invention.

FIG. 3 is a bottom view of the essential parts of the polisher of the polishing apparatus according to the embodiment of the present invention.

FIG. 4 is an enlarged configuration diagram of a main part of a polishing apparatus according to an embodiment of the present invention.

FIG. 5 is a sectional view of a constant velocity ball joint of a polishing device according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

1: Workpiece, 2: Workpiece holding part, 3: Polisher, 3
a: polisher pressurizing part, 4: polisher holding part, 5: working liquid, 6: working liquid supply part, 7: working tank, 13: swing drive part, 16: opening, 18: working liquid guide hole.

Claims (6)

[Claims] 1. A polishing liquid is inserted between a work piece and a polisher, and the work piece and the polisher are relatively moved to polish the work piece with the polisher in a non-contact manner. In the polishing method, the step of completely immersing the workpiece and the polisher in the working liquid,
And a step of supplying the working liquid, which has passed through the inside of the polisher, to the workpiece from the side of the facing surface of the polisher with respect to the workpiece. 2. A polishing apparatus having the following structure. (A) First rotation driving means for holding and rotating the workpiece. (B) A polisher that comes into contact with the workpiece through a polishing liquid. (C) Second rotation driving means for holding and rotating the polisher. (D) Swing drive means for swinging the polisher held by the second rotation drive means relative to the workpiece with which the polisher is in contact. (E) A pressing means for elastically pressing the polisher against the work piece. (F) A machining fluid holding means for accommodating the machining fluid and immersing the workpiece and the polisher in the stored machining fluid. (G) Machining liquid supply means for passing the machining liquid through the inside of the polisher and supplying the machining liquid to the workpiece from the surface of the polisher facing the workpiece. 3. The polishing apparatus according to claim 2, further comprising a working liquid temperature control means for controlling the working liquid at a constant temperature. 4. The polishing apparatus according to claim 2, further comprising a working fluid stirring means for stirring the working fluid contained in the working fluid holding means. 5. A polishing liquid guide hole is formed in the polisher at a plurality of positions on the surface facing the workpiece, and penetrates through the inside of the polisher. The polishing apparatus according to claim 2, wherein the processing liquid is supplied by the processing liquid supply means. 6. The polishing apparatus according to claim 2, wherein a constant velocity ball joint is provided on the rotary shaft of the first rotary drive means or the second rotary drive means.