JP2001071245A - Polishing tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing tool capable of dealing with a machined surface having a wide variety of curvatures such as an aspheric lens by itself, and smoothing the machined surface with a simple structure. SOLUTION: This polishing tool has a polishing pad 2 mounted on a plate-like member 3 including a peripheral part fixed to a post member 4; an actuator 5 for displacing the plate-like member 3 in the pressing direction of a polishing face 2a; a drive control means 7 driving the actuator 5; and a calculation control means 8 calculating a machining surface shape according to a machining position and deforming the polishing pad 2 through the drive control means 7. By driving the actuator 5 according to the designed ideal machining surface shape in an arbitrary machining position calculated by the calculation control means 8, the plate-like member 3 mounted with the polishing pad 2 is deformed to forcibly make the polishing face 2a of the polishing pad 2 coincide with the ideal machining surface shape. By closely contacting the polishing face 2a with a machined surface with no gap and uniformly applying a machining pressure, the machined surface including minute undulation can be smoothed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing tool used for polishing an optical element such as a lens or a mirror or a mold, and more particularly to a variable-shape polishing tool used for ultra-precision polishing. is there.

[0002]

2. Description of the Related Art Polishing tools using a polisher made of an elastic material have been conventionally used for finish polishing of optical elements such as lenses and mirrors or molds, etc., which require high form accuracy. By pressing the polished surface of the polisher against the surface to be processed and supplying a polishing liquid between the polished surface and the surface to be processed, the polisher is rotated or oscillated with respect to the surface to be processed to perform the processing. I have. At this time, if the surface to be processed is a spherical surface, the surface of the polisher is usually formed with high precision so that the required radius of curvature of the spherical surface matches.

[0003] By the way, the shape of the workpiece varies.
For example, when the radius of curvature such as an aspherical surface changes, as described above, the 1
When processing is performed only with the type of polishing tool, it is not possible to cope with a curvature that changes on the surface to be processed (hereinafter, also simply referred to as R), and there is a difference in curvature between the polishing surface of the polishing tool and the surface to be processed. A difference in pressure distribution occurs on the surface to be processed that the polishing tool contacts, and the polishing cannot be performed uniformly. In an extreme case, a gap may be formed between the polished surface and the surface to be processed, and only a part of the polished surface may affect the processing.

In addition, as the polishing process progresses, the shape of the polished surface of the polisher is gradually deformed and deteriorated.
In order to maintain a constant curvature, it is necessary to reshape the polished surface by an operation such as rubbing. The labor and time spent in the rubbing operation and the interruption of the polishing process during that time lead to a reduction in manufacturing efficiency and an increase in manufacturing cost.

From the above, there has been proposed a polishing tool for processing capable of arbitrarily forming a polished surface of a tool member so that various radii of curvature can be processed, for example, Japanese Patent Publication No. 5-58864. The gazette discloses a polishing tool in which a plurality of actuators are used to change the shape of the polishing surface, that is, the curvature of the polishing surface.

In this conventional polishing tool, as shown in FIG. 9, a plurality of displacement actuators 102 which can be individually operated by a control means (not shown) are two-dimensionally arranged on a base 101, A tool member 1 made of an elastic body that forms a tool surface having an arbitrary curvature as a whole on an output-side member 103 that is displaced by the operation of the actuator 102.
04 is attached.

When machining is performed by relatively sliding the tool member 104 with respect to the workpiece using the polishing tool, the displacement actuators 102 are operated during the machining, and the shape of the tool member 104 is changed. Are partially and independently changed to adjust the force for individually pressing the surface to be processed to form a desired curved surface as a whole.

[0008]

However, the above-mentioned conventional polishing tool has the following problems.

Since the plurality of displacement actuators 102 are individually controlled to obtain a desired curved surface shape, the structure of the apparatus is complicated and expensive, and particularly, the curvature is continuously and minutely changed. A gentle curved surface (for example,
In the case where the amount of aspherical surface, which is a deviation from the spherical surface, is about 0.1 mm), it is not necessary to rapidly change the curvature of a part in the plane of the tool member 104. There was a problem that the effect was small.

For a work surface having a large change in curvature and a large value (for example, the maximum value of the amount of aspherical surface which is a deviation from the spherical surface is 0.5 mm or more), the yield stress of the member serving as a polisher, and A polishing tool (for example, φ20 mm) having a sufficiently small area must be configured due to restrictions on the size and the like, so that a plurality of displacement actuators are two-dimensionally arranged on the tool surface. (Even small, φ10 mm) is physically difficult.

Accordingly, the present invention has been made in view of the above-mentioned unsolved problems of the prior art,
An object of the present invention is to provide a polishing tool that can cope with a work surface having a variety of curvatures, such as an aspherical lens, with a single tool, and can smoothly smooth the work surface with a simple configuration. It is assumed that.

[0012]

In order to achieve the above object, a polishing tool according to the present invention comprises a polishing pad having a polishing surface, a plate-like member to which the polishing pad is attached, and a peripheral portion of the plate-like member. A support member attached in the direction of pressing the polishing surface, a base member holding the support member, one actuator for displacing the plate-like member in the direction of pressing the polishing surface, and a processing surface shape according to a processing position And a drive control means for driving the actuator so as to match the surface shape calculated by the calculation control means.

[0013] In the polishing tool according to the present invention, it is preferable that the actuator is attached to the plate-like member, and displaces the plate-like member in a pressing direction of the polishing surface. Is preferably attached to the central part in the longitudinal direction and the lateral direction.

In the polishing tool according to the present invention, it is preferable that a peripheral portion of the plate-shaped member is attached to the support member so as to be movable in a direction orthogonal to a pressing direction of the polishing surface.

Furthermore, in the polishing tool of the present invention,
The actuator is attached to the support member,
It is preferable that the support member be displaced in a direction perpendicular to the pressing direction of the polishing surface.

In the polishing tool according to the present invention, the support member is composed of at least two parts, at least one part of the support member is fixed to the base member, and the remaining part of the support member is It is preferable that the support member is movably mounted on the base member in a direction orthogonal to the pressing direction of the polishing surface, or the support member is composed of at least two parts, and each part of the support member is It is preferable that the base member is mounted so as to be movable in a direction orthogonal to a pressing direction of the polishing surface.

In the polishing tool of the present invention, it is preferable that the polishing tool is provided with a symmetrical moving mechanism for moving the respective portions of the column member symmetrically with respect to the central axis, and a ball screw mechanism can be used as the symmetrical moving mechanism.

In the polishing tool of the present invention, it is preferable that a tension or compression preload means is interposed between the plate member and the base member in a pressing direction of the polishing surface.

In the polishing tool according to the present invention, the arithmetic control means calculates a value of a radius of curvature as a shape of a processing surface at a processing position, and calculates a required displacement amount of the actuator required to form the radius of curvature. It is preferable to perform the calculation.

In the polishing tool of the present invention, there is provided a displacement detecting means for measuring a displacement of a central portion of the plate-like member,
It is preferable that the arithmetic control unit and the drive control unit are configured to correct a difference between the actual displacement amount detected by the displacement detection unit and the required displacement amount.

[0021]

According to the polishing tool of the present invention, the designed ideal machining surface shape at an arbitrary machining position is calculated by the arithmetic control means, and one actuator is driven to directly connect the plate-like member. Alternatively, the plate-like member to which the polishing pad is attached can be deformed through a column member to which the peripheral portion of the plate-like member is attached, and the polishing surface shape of the polishing pad can be forcibly matched to the ideal machined surface shape. In addition, the polishing surface of the polishing pad is brought into close contact with the surface to be processed without any gap, and the processing pressure can be uniformly applied to the surface to be processed. As a result, the workpiece can be polished smoothly and over the entire surface, and the surface to be processed can be smoothed including minute undulations (ripples), which are relatively short-wavelength shape error components.

Although the shape of the surface to be processed before polishing is deviated from a generally designed ideal shape,
By forcibly deforming and shaping the shape of the polishing tool, the difference in pressure formed in the polished surface can be used to correct the shape of the polished surface and bring it closer to the ideal shape. .

As described above, according to the present invention, a work surface having a variety of curvatures, such as an aspherical lens, can be handled by a single tool, and a work surface having a variety of curvatures can always be formed. Polishing can be performed with a uniform pressure distribution, and a desired shape can be obtained.

[0024]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a polishing tool according to a first embodiment of the present invention, and FIG. 2 is a view showing the use of the polishing tool according to the first embodiment of the present invention. FIG. 3 is a schematic diagram showing a state of processing an optical lens).

The polishing tool 1 shown in FIG. 1 and FIG.
Polishing pad (polisher) 2, plate-like member 3 to which polishing pad 2 is attached, support member (hereinafter also simply referred to as support) 4 for fixing the peripheral portion of plate-like member 3, and displaceable actuator 5 And a base 6 for holding the support member 4, a drive control means 7 for driving and controlling the actuator 5, and a calculation control for calculating a processing surface shape at a processing position and transmitting the calculation result to the drive control means 7. Means 8 are provided.

The polishing pad 2 is fixedly attached to the lower surface of a plate-like member 3 made of phosphor bronze, thin plate spring steel, or the like by means of bonding or the like, and the lower surface is a polishing surface 2a.
The polishing pad 2 is made of a pitch, urethane foam, or the like, and has a rectangular shape having a longitudinal direction and a lateral direction in FIG. 1, but may have a disk shape, and the shape is not limited. Absent. Although FIG. 1 shows the polishing pad 2 as being divided into two,
It may be a single piece that is connected in its entirety, or may be one that forms a groove on the polishing surface 2a instead of being divided.

The support member 4 is a fixed support fixedly attached to the lower surface side of the base 6, and the lower surface of the fixed support 4 has a peripheral portion of the plate member 3 (in this embodiment, a peripheral portion). Both ends) are fixed by means such as screwing or bonding.

The displaceable actuator 5 is arranged such that one end thereof is fixed to the base 6 and the lower end displaceable in the vertical direction of the drawing is connected to the central part of the plate-like member 3 in the longitudinal and transverse directions. When the lower end of the actuator 5 is displaced in the direction of arrow A with reference to the base 6, the actuator 5 also displaces the central portion of the plate-like member 3 in the vertical direction (arrow B in the drawing). At this time, the plate member 3
Since the peripheral portion is fixed to the base 6 via the fixed column 4, only the central portion thereof is displaced in the vertical direction to form a convex or concave curvature surface. The polishing surface 2a of the fixed polishing pad 2 also has a curvature surface in a similar manner.

As the actuator 5, a voltage displacement conversion element such as a piezo element is used when a high-speed response is required, and an air cylinder or the like is selected when a response is not required but a large stroke is required. Used. In addition, it is also possible to attach a mechanism (for example, a rack and a pinion mechanism) to a rotary motor and convert it to a direct drive type.

Reference numeral 7 denotes a drive control means connected to the actuator 5 for driving and controlling the actuator 5, and 8 calculates a processing surface shape such as a Z coordinate on the XY plane and a radius of curvature at the processing position. The operation control means (for example, CPU) is connected to the drive control means 7 to perform an operation necessary for driving the drive control means 7 and to transmit an operation result to the drive control means 7. is there.

In FIG. 2, L is a workpiece such as an optical lens having a convex aspherical surface symmetrical with respect to the central axis, for example, by vacuum suction or screwing or bonding through a jig (not shown). Driving means (not shown) such as a motor that is fixed to the holder H and rotates at a constant speed along the center axis N of the holder H is attached. The polishing surface 2a of the polishing pad 2 is pressed against the processing surface La of the processing object L via a polishing agent (not shown), and polishing is performed.
The polishing pad 2 and the plate member 3 used for polishing the processing surface La are set to dimensions sufficiently smaller than the processing surface La. For example, a rectangular polishing pad 2 of 20 mm × 6 mm is used for a processing surface La having a diameter of 100 mm.

Next, the polishing tool 1 configured as described above
The mode in which the workpiece L is polished by using is described.

The workpiece L is attached to the holder H, and is rotated clockwise around the central axis N at a constant rotation speed Wr (for example, 10 rpm) by a driving means (not shown). The polishing tool 1 is moved radially outward (arrow C in the drawing) from a position on the central axis N, which is the vertex of the processing surface La of the workpiece L, at a constant speed v (for example, 5 mm / min). Moving. Therefore, apparently, the polishing tool 1 is spirally scanned on the workpiece L from the center of the workpiece surface La toward the outer periphery.

At this time, the polishing tool 1 has an amplitude h and a frequency f (for example, an amplitude (h) of 2 mm and a frequency (f) of 2 Hz, ie, a speed vr (> v, The work surface La is machined while swinging in the radial direction (for example, 25 mm / sec)) in the radial direction (arrow D in the figure). Furthermore, in the polishing tool 1, it goes without saying that a load required for processing is applied from the polishing surface 2a of the polishing pad 2 to the processing surface La.

The processing position of the workpiece L can be predicted in advance based on the rotational speed Wr of the workpiece L and the moving speed v of the polishing tool in the radial direction. The radius R is obtained, and the actuator 5 of the polishing tool 1 is driven via the drive control means 7,
The shapes of the plate member 3 and the polishing pad 2 can be made to match the desired radius of curvature R. This means that when the polishing tool is near the center of the workpiece L (the radius of curvature R1,
The same holds true for R1 = about 300 mm) and when it is near the outer circumference (curvature radius R2 <R1, for example, R2 = 200 mm).

As described above, the ideal processing surface shape (for example, radius of curvature) at an arbitrary processing position is calculated by the operation control means 8 provided outside, and the polishing pad 2 is forcibly adjusted to this processing surface shape. The actuator 5 having one end fixed to the base 6 is driven so that the plate member 3 to which the polishing pad 2 is attached is bent and deformed. As a result, the polishing surface 2a of the polishing pad 2 and the surface to be processed La are brought into close contact with no gap, and the load applied to the polishing tool 1 is uniformly applied to the surface to be processed La as the processing pressure.

As described above, processing is performed smoothly and over the entire surface within the range in which the polishing tool 1 moves, and the surface to be processed including minute undulations (ripples) can be smoothed.

Since the shape of the surface to be processed La deviates from a generally designed ideal shape, the pressure formed in the polishing surface 2a is formed by forcibly forming and processing the shape of the polishing pad 2. By utilizing the difference between the two, it is possible to correct the shape of the processing target surface La so as to approach the ideal shape.

As described above, by using the polishing tool of the present embodiment, it is possible to polish a work surface having various curvatures, such as an aspherical lens, with a uniform pressure distribution. A single tool can cope with a work surface having a variety of curvatures.

Next, a polishing tool according to a second embodiment of the present invention will be described with reference to FIGS. The first mentioned above
In the embodiment, the plate-like member 3 is fixed to the fixed column 4 and the expansion and contraction of the plate-like member 3 corresponds to the change in the radius of curvature. However, in this embodiment, both ends of the plate-like member 3 are used. The portion is slidably attached to the fixed support 4 in the left-right direction on the paper surface, so that the length of the portion forming the curved surface shape can be adjusted, and the corresponding range of the shape change can be expanded. Things. In the present embodiment, the same members as those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, the plate-like member 3 has both end portions 3a, 3a bent upward in the drawing, and through-holes 3b for inserting the guide pins 9 in the respective portions. The guide pins 9 are attached to the outer sides of the fixed supports 4, 4 via the through holes 3 b of the plate-like member 3, and the guide pins 9 are attached to the fixed supports 4.
Part 3a bent upwardly of the outer surface of the plate member 3 and the plate member 3
And the coil springs 10 are inserted between them. These coil springs 10 act as a preload mechanism for expanding both end portions 3a of the plate member 3 outward. By adopting such a configuration, the plate-shaped member 3 has its ends 3a slidable in the left-right direction, so that the range of the shape is not determined by relying only on the elasticity of the material, but is fixed. Since the length of the portion where the shape of the plate-shaped member 3 is changed with respect to the support 4 can be adjusted, it is possible to cope with a wider range of shapes. Note that the coil spring 10 may be inserted between the end of the guide pin 9 and the end 3a of the plate member 3 so as to apply a preload in a direction to contract the plate member 3 inward.

Further, instead of the guide pin 9, it is also possible to use an ultra-compact linear slide or the like. In this case, the fixed side of the linear slide is fixed to the fixed column 4 and attached to the end 3a of the plate member 3 on the slide table side.

FIG. 4 shows an example of the polishing tool of this embodiment.
A state in which an aspherical lens having a large change in curvature, which is concave near the center of the workpiece L and convex near the outer periphery, is illustrated. Also in the present embodiment, the plate-shaped member 3 can be deformed so as to conform to the radius of curvature designed according to the processing position on the surface to be processed La near the center or the outer periphery, as shown in FIG. Even when the change in the radius of curvature such as a transition from a concave surface to a convex surface is large, the polishing surface 2a of the polishing pad 2 and the processing surface La are in close contact with no gap, and the load applied to the polishing tool 1 is applied as a processing pressure. It is uniformly applied to the processing surface La.

As described above, in this embodiment, the same operation and effect as those of the first embodiment can be obtained, and the shape of the plate-like member can be changed only by adding a relatively simple mechanism. Since the length of the portion to be adjusted can be adjusted, it is possible to cope with a wider range of shapes.

Next, a polishing tool according to a third embodiment of the present invention will be described with reference to FIGS.

In each of the above-described embodiments, the plate member 3
Is fixedly attached to the base 6 with the support member 4 for attaching the
Although the displaceable actuator 5 is fixed to the base 6 and the displaceable end is directly fixed to the plate-like member 3, in the present embodiment, the support member is constituted by at least two parts, One of the movable members is movable, and the actuator 5 is attached to a movable support to displace the plate-like member 3 via the support. The details will be described below.

As shown in FIG. 5, the support member 4 includes a fixed support 4a fixed to the lower surface of the base 6 and a fixed support 4a along a guide 6b provided on the lower surface of the base 6.
And a movable support 4b movably provided (in the direction of arrow E) so as to be able to approach and separate from the fixed support 4.
A peripheral portion of the plate-shaped member 3 (in this embodiment, both peripheral ends) is fixed to the lower surface of each of the movable column 4a and the movable support 4b by means such as screwing or bonding.

An actuator 5 which can be displaced in the horizontal direction of the drawing is disposed between the fixed support 4a and the movable support 4b. The actuator 5 moves the movable support 4b toward or away from the fixed support 4a. Driven.

The drive control means 7 is connected to the actuator 5 in the same manner as in each of the above-described embodiments.
Similarly, the arithmetic and control unit 8 connected to the drive control unit 7 calculates the machining surface shape such as the Z coordinate and the radius of curvature on the XY plane at the machining position, and is necessary for driving the drive control unit 7. And to transmit the calculation result to the drive control means 7.

In FIG. 5, reference numeral 11 denotes a preload coil spring connected between the base 6 and the plate member 3 for applying a pressure to the plate member 3. By making the length shorter than the distance between the base 6 and the plate-shaped member 3, a force in the pulling direction acts on both ends of the preload coil spring 11, so that the plate-shaped member 3 is always bent upward in the drawing. As a result, the polishing surface 2a of the polishing pad 2 tends to have a concave shape. On the other hand, in order to make the polishing surface 2a of the polishing pad 2 easy to make a convex shape, if the natural length of the preload coil spring 11 is longer than the distance between the base 6 and the plate member 3, the preload coil Spring 11
Due to the reduced repulsive force, the plate-shaped member 3 is bent in a direction to push it downward in the plane of the drawing, and the polishing surface 2a is likely to have a convex shape. In any case, the preload coil spring 1
It is necessary that the rigidity of 1 is sufficiently low and adjusted so that free deformation of the plate-like member 3 is not hindered.

Next, the actuator 5 in this embodiment is
The operation of changing the shape of the polishing surface 2a of the polishing pad 2 by the displacement of the polishing pad 2 will be described.

When the actuator 5 is displaced in the direction of arrow E with respect to the fixed support 4a fixed to the base 6, the movable support 4b also moves in the left-right direction on the paper along the guide 6b. For example, when the movable support 4b is moved to the left in the drawing, the distance between the fixed support 4a and the movable support 4b is reduced. As a result, the plate-like member 3 that has been previously pulled up by the preload coil spring 11
Is largely bent and displaced upward in the drawing. At this time, since the peripheral portion of the plate-shaped member 3 is fixed to the fixed column 4a and the movable column 4b of the column member 4, it is not displaced in the vertical direction on the paper. Therefore, only the central portion of the plate member 3 bends to form a convex or concave curvature surface (R surface), and the polishing surface 2a of the polishing pad 2 fixed to the plate member 3 also has a similar curvature. Plane (R plane). As described above, the bending shape of the plate-shaped member 3 is appropriately changed without changing its length. Since the amount of deflection between the actuator 5 and the central portion of the plate-shaped member 3 corresponds one-to-one, if this relationship is grasped in advance, the actuator 5 can be displaced to form a desired curvature surface (R surface). Is possible.

Further, since the distance between the movable column 4b and the fixed column 4a is changed by the driving of the actuator 5, the position of the central portion of the plate-like member 3 serving as the center of the deflection (ie, the central axis of the polishing surface 2a). M position) also constantly changes in the left-right direction on the paper. However, in the arithmetic control means 8,
The shift amount of the center position is calculated according to the displacement of the actuator 5 at an arbitrary processing position, the center position is corrected on the moving mechanism of the polishing tool device, and the axis of the radius of curvature center at the processing position and the polishing surface 2a Can be adjusted to the center axis N.

An embodiment in which the workpiece L is polished using the polishing tool of the present embodiment configured as described above will be described. The workpiece L is attached to the holder H, and is rotated clockwise around the central axis N at a constant rotation speed Wr (for example, 10 rpm) by a driving unit (not shown). The polishing tool 1 has a center axis N which is a vertex of a processing surface La of the processing object L.
It moves at a constant speed v (for example, 5 mm / min) from the upper position outward in the radial direction (arrow C in the figure). Therefore, apparently, the polishing tool 1
a is spirally scanned from the center of the processing surface La toward the outer periphery. In the polishing tool 1, it goes without saying that a load required for processing is applied from the polishing surface 2a of the polishing pad 2 to the surface to be processed La.

At this time, the polishing tool 1 has an amplitude h and a frequency f (for example, an amplitude (h) of 2 mm and a frequency (f) of 2 Hz, ie, a speed vr (> v, The work surface La is machined while swinging in the radial direction (for example, 25 mm / sec)) in the radial direction (arrow D in the figure).

The processing position of the workpiece L can be predicted in advance from the rotational speed Wr of the workpiece L and the moving speed v of the polishing tool in the radial direction. The radius R is determined, the actuator 5 of the polishing tool 1 is driven, and the shapes of the plate member 3 and the polishing pad 2 can be made to match the desired radius of curvature R. This means that even when the polishing tool is near the center of the workpiece L (the radius of curvature R1, for example, about R1 = 300 mm), it is also near the outer periphery (the radius of curvature R2 <R1,
The same is true for R2 = 200 mm).

One end of the polishing pad 2 is forcibly matched with the ideal processing surface shape (for example, radius of curvature) at an arbitrary processing position calculated by the arithmetic means 8 provided outside. Drives the actuator 5 fixed to the fixed support 4a, moves the movable support 4b in the left-right direction on the paper surface, and moves the plate-like member 3 on which the polishing pad 2 is attached.
Bend and deform. As a result, the polishing surface 2a of the polishing pad 2 and the surface to be processed La are brought into close contact with no gap, and the load applied to the polishing tool 1 is uniformly applied to the surface to be processed La as the processing pressure.

As described above, processing is performed smoothly and over the entire surface within the range in which the polishing tool 1 moves, and the surface to be processed including minute undulations (ripples) can be smoothed.

Since the shape of the surface to be processed La generally deviates from the designed ideal shape, the shape of the polishing tool is forcibly formed and processed to reduce the pressure formed in the polishing surface 2a. By utilizing the difference, the shape of the processing target surface La can be corrected so as to be closer to the ideal shape.

As described above, by using the polishing tool of this embodiment, a single tool can cope with a work surface having a variety of curvatures, such as an aspherical lens, and the configuration and control can be performed easily. Possible polishing tools can be provided.

Next, a polishing tool according to a fourth embodiment of the present invention will be described with reference to FIG.

In this embodiment, all the support members 4 (4a, 4b) in the third embodiment described above are replaced with movable supports 4c, 4d which can move in the left-right direction on the paper, and a symmetrical moving mechanism (for example, Ball screw mechanism). In the present embodiment, the same reference numerals are given to the same members as the members in each of the above-described embodiments.
Detailed description is omitted.

In the embodiment shown in FIG. 7, the movable columns 4c and 4d are provided with guides 6 provided on the lower surface of the base 6.
The peripheral portions of the plate-shaped member 3 (in the present embodiment, both ends of the periphery) are fixed to the lower surfaces of the respective lower surfaces of the plate-shaped members 3 along the positions c and 6d.
Then, an actuator 5 composed of a ball screw mechanism
a is fixed to the base 6 via a spacer 5c, and opposite ends of a screw shaft 5b extending in both the left and right directions from the actuator 5a are formed with opposite screws.
c and 4d are respectively provided with screw holes screwed to both ends of the screw shaft 5b of the actuator 5a.
When the ball screw mechanism of the actuator 5a is driven to rotate in the direction of arrow G, the moving columns 4c and 4d move in the direction of arrow H and move in parallel so as to approach the central axis M,
When the ball screw mechanism is rotationally driven in the direction opposite to the arrow G, the moving columns 4c and 4d move in the direction opposite to the arrow H and move parallel to each other so as to move away from each other about the center axis M. It is configured.

The present embodiment having the above-described structure has the following advantages in addition to the functions and effects of the third embodiment. That is, since the threaded portions at both ends are cut in opposite directions, the operation of the actuator 5a causes the movable supports 4c and 4d to move symmetrically about the central axis M, and
Position of the polishing tool does not always change, and the arithmetic and control unit 8 outside the polishing tool
In this case, there is an advantage that the calculation of the displacement and the correction thereof are not required.

Next, a polishing tool according to a fifth embodiment of the present invention will be described with reference to FIG.

In this embodiment, the polishing tool described as the fourth embodiment is provided with a displacement detecting means 13 for measuring the displacement of the central portion of the plate-like member 3. 13 measures an actual displacement amount (hereinafter, also referred to as an actual displacement amount) of a central portion of the plate-shaped member 3 and sends the actual displacement amount to the drive control means 7 and the arithmetic control means 8 so that the actual displacement amount is calculated. A comparison is made between an ideal machined surface shape, a displacement amount required to match the ideal machined surface shape (hereinafter, also referred to as a required displacement amount), and feedback control for correcting the difference is performed. It is what was constituted.

For example, when a strain gauge is used as the displacement amount detecting means 13, the strain gauge is attached to the back surface of the plate member 3 (the side opposite to the polished surface 2a). Are the preload coil spring 11 and the plate member 3
Into the connection. Regardless of the type of strain gauge or load cell used, to convert the amount of detection into the amount of displacement, measure the curve of strain and displacement or the curve of load and displacement before assembling it in the polishing tool and measure the relationship between the two. Will be clarified.

Also, a displacement sensor can be used as the displacement amount detecting means 13. In this case, the displacement sensor is fixed to the base 6 in the pressing direction, and the displacement of the central portion of the plate member 3 is detected.

The displacement detecting means 13 is connected to the arithmetic and control means 8 via the drive control means 7, and the arithmetic and control means 8 takes in the amount (for example, distortion) detected by the displacement detecting means 13. After being converted to the actual displacement,
Compared with the required displacement, the difference is the amount to be corrected,
A control signal is sent from the drive control means 7 to the actuator 5a.

In the present embodiment configured as described above, it is possible to constantly monitor the amount of deflection of the plate-shaped member 3 and correct it so that it matches the amount of deflection necessary to form a desired curvature. Therefore, there is an advantage that the plate-shaped member 3 and the polishing pad 2 can be maintained with high precision by an ideal machined surface shape.

Although the present embodiment has been described with reference to the example in which the displacement amount detecting means is added to the fourth embodiment, the polishing tool of each of the first to third embodiments described above can also be applied to the polishing tool of the first to third embodiments. It goes without saying that a displacement amount detecting means for measuring the displacement amount can be additionally provided.

[0073]

As described above, according to the present invention,
By incorporating one actuator into the polishing tool, a desired processed surface shape can be obtained, and the polishing tool can be simply and inexpensively constructed. In particular, in the case of an aspherical shape whose curvature continuously changes, it is not necessary to change the curvature partially in the polished surface, and it is possible to make any ideal machined surface shape with a minimum amount of labor and cost. And the maximum effect can be obtained.

Further, a polishing tool having a sufficiently small area may be required to be formed on a surface to be processed having a large change in curvature due to a yield stress of a member to be a polishing pad, a size that can be formed, and the like. However, in such a case, since the polishing tool of the present invention uses only a single actuator, it is suitable for forming a tool having a small polishing surface corresponding to a surface having a small curvature.

Further, the polishing surface shape of the polishing tool can be forcibly matched to the ideal processing surface shape, the polishing surface of the polishing pad and the work surface are in close contact with no gap, and the load applied to the polishing tool is Can be uniformly applied to the surface to be processed as the processing pressure, and the processing is performed smoothly and over the entire surface within the moving range of the polishing tool, resulting in minute undulations (ripples).
And the surface to be processed can be smoothed.

Further, since the shape of the surface to be processed before being polished deviates from a generally designed ideal shape, the shape of the polishing tool is forcibly formed and processed to form the polished surface. By utilizing the difference in the applied pressure, the shape of the surface to be processed can be corrected so as to approach the ideal shape.

As described above, a single tool can cope with a work surface having a variety of curvatures, such as an aspheric lens.
In addition, a work surface having a variety of curvatures can be polished with a uniform pressure distribution, and a controllable polishing tool with a simple configuration can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view of a polishing tool according to a first embodiment of the present invention.

FIG. 2 is a schematic view showing a state in which an axisymmetric convex aspherical shape is machined using the polishing tool according to the first embodiment of the present invention.

FIG. 3 is a schematic view of a polishing tool according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram showing a state in which an aspherical shape in which the radius of curvature changes greatly from concave to convex using the polishing tool according to the second embodiment of the present invention.

FIG. 5 is a schematic view of a polishing tool according to a third embodiment of the present invention.

FIG. 6 is a schematic diagram showing a state in which an axisymmetric convex aspherical shape is machined by using the polishing tool according to the third embodiment of the present invention.

FIG. 7 is a schematic view of a polishing tool according to a fourth embodiment of the present invention.

FIG. 8 is a schematic view of a polishing tool according to a fifth embodiment of the present invention.

FIG. 9 is a perspective view showing an example of a conventional polishing tool.

[Explanation of symbols]

 Reference Signs List 1 polishing tool 2 polishing pad 2a polishing surface 3 plate member 4 support (member) 4a fixed support 4b moving support 4c, 4d moving support 5 actuator 5a actuator (ball screw mechanism) 5b screw shaft 6 base (member) 6b, 6c, 6d Guide 7 Drive control means 8 Arithmetic control means 9 Guide pin 10 Coil spring 11 Preload coil spring 13 Displacement detection means L Workpiece (optical lens) La Workpiece surface

Claims (12)

[Claims] 1. A polishing pad having a polishing surface, a plate-like member to which the polishing pad is attached, a support member for attaching a peripheral portion of the plate-like member in a pressing direction of the polishing surface, and a base for holding the support member A member, one actuator for displacing the plate-shaped member in the pressing direction of the polishing surface, arithmetic control means for calculating a processing surface shape according to a processing position, and a surface shape calculated by the arithmetic control means. A polishing tool, comprising: drive control means for driving the actuator so as to match. 2. The polishing tool according to claim 1, wherein the actuator is attached to the plate member, and displaces the plate member in a direction in which the polishing surface is pressed. 3. The polishing tool according to claim 2, wherein the actuator is attached to a central portion of the plate-like member in a longitudinal direction and a lateral direction. 4. The plate-shaped member has a peripheral portion attached to the support member so as to be movable in a direction orthogonal to a pressing direction of the polishing surface. 3. The polishing tool according to 3. 5. The polishing tool according to claim 1, wherein the actuator is attached to the support member, and displaces the support member in a direction orthogonal to a pressing direction of the polishing surface. 6. The support member comprises at least two parts, at least one part of the support member is fixed to the base member, and the remaining part of the support member is connected to the base member. The polishing tool according to claim 5, wherein the polishing tool is mounted so as to be movable in a direction orthogonal to a pressing direction of the polishing surface. 7. The support member includes at least two parts, and each part of the support member is mounted on the base member so as to be movable in a direction orthogonal to a pressing direction of the polishing surface. The polishing tool according to claim 5, wherein: 8. A polishing tool according to claim 7, further comprising a symmetrical moving mechanism for moving each part of said support member symmetrically with respect to a central axis. 9. The polishing tool according to claim 8, wherein said symmetric moving mechanism is constituted by a ball screw mechanism. 10. The apparatus according to claim 6, wherein a tension or compression preload means is interposed between the plate-shaped member and the base member in a pressing direction of the polishing surface. Polishing tool according to item. 11. The arithmetic control unit calculates a value of a radius of curvature as a processing surface shape at a processing position, and calculates a required displacement amount of the actuator required to form the radius of curvature. The polishing tool according to any one of claims 1 to 10. 12. A displacement amount detecting means for measuring a displacement amount of a central portion of the plate-like member, wherein the arithmetic control means and the drive control means determine an actual displacement amount detected by the displacement detecting means. 2. The apparatus according to claim 1, wherein a difference between required displacement amounts of said actuator is corrected.
Item 2. The polishing tool according to any one of Items 1.