JP3885964B2 - Curved surface polishing apparatus and curved surface polishing method - Google Patents

Description

  The present invention relates to a curved surface polishing apparatus and a curved surface polishing method for polishing a curved surface of a lens mold or an optical component.

Optical parts such as lenses used in various optical devices and optical communication devices, molds for forming lenses, and the like have convex or concave curved surfaces. Since optical components require extremely high shape accuracy, high accuracy is also required in polishing such optical components and molds.
On the other hand, lenses used in optical devices and the like are roughly classified into spherical lenses whose curved surface shape is spherical and aspherical lenses which are also aspherical. Aspherical lenses have been widely used in recent years because they have many advantages such as a short focal point with no spherical aberration and a reduced number of lenses compared to spherical lenses. Polishing may be performed for surface finishing of these lenses and a mold for molding the lenses. In particular, the mold surface usually needs to be finished by polishing.

  As a polishing apparatus and a polishing method for polishing a curved surface shape with high shape accuracy, there is one described in Patent Document 1. This polishing apparatus includes a pedestal (holder) that holds and fixes the flat side of a concave lens that is a workpiece, and a shaft that holds the pedestal so that it can tilt and rotate. In addition, a rocking mechanism for rocking the concave lens together with the pedestal and the shaft body is provided. The oscillation center of the oscillation is the center of curvature of the concave spherical surface that is the surface to be processed of the lens. Further, this polishing apparatus has a hemispherical grindstone (fixed abrasive tool) having a radius of curvature as a desired polishing shape. The polishing method using this apparatus rotates the grindstone while pressing the hemispherical grindstone against the entire concave spherical surface of the concave lens by surface contact, and performs the rocking on the lens side which is the workpiece, thereby forming the shape of the grindstone (that is, This is an apparatus for polishing while transferring a spherical shape having a desired radius of curvature to a concave lens. According to this polishing method, it is possible to polish a spherical shape having a desired radius of curvature (see Patent Document 1).

JP 2001-38594 A (FIG. 1, page 3)

  In the above-described conventional polishing apparatus and polishing method, the concave spherical surface and the convex spherical surface are polished while being swung along the spherical surface, so that the spherical surface can be polished, but the aspherical surface cannot be polished. Accordingly, it is not possible to polish aspherical surfaces such as aspherical lenses and lens molding molds for molding aspherical lenses that have increased in recent years. Furthermore, in the case of an aspherical lens or an aspherical lens molding die, if there is a shape error in the workpiece before polishing, the error may be corrected by polishing to create a desired aspherical shape. Can not.

  The present invention has been made in view of the above situation, and can be polished with high precision even on an aspherical surface, and can also create a desired aspherical shape. An object is to provide an apparatus and a curved surface polishing method.

In the curved surface polishing apparatus of the present invention, a rotating mechanism for rotating an object to be polished and a polishing body having a spherical polishing surface at a lower end are fixed, and the spherical polishing surface of the polishing body is rotated by the rotating mechanism. and abrasive tool bar-like polishing the upper surface of the said workpiece by Rukoto was spot contact with the upper surface of the workpiece to the rotation the like contact position between the polishing body and the object to be polished is changed In a state where the first swing mechanism having a first swing support portion for swinging the mechanism while tilting, and the object to be polished and the polishing body are in contact with each other, the polishing tool is polished in the spherical shape. A second oscillating mechanism having a second oscillating support for oscillating around an axis passing through the center of curvature of the surface or the vicinity thereof, and controlling the oscillation by the first oscillating mechanism to Control the contact time at each contact position on the polishing object. Characterized in that it comprises a swing control mechanism that, the.

The polishing method of the present invention is a polishing method in which polishing is performed by rotating the object to be polished in a state where the object to be polished and the object to be polished having a spherical polishing surface are in spot contact. Then, while the object to be polished and the polishing surface of the polishing body are in contact with each other, the polishing object is swung around an axis passing through the center of curvature of the spherical polishing surface or the vicinity thereof, and the object to be polished The polishing is performed by changing the contact position of the object to be polished with respect to the polishing body by swinging the object, and each contact on the object to be polished is controlled by controlling the swing of the object to be polished. Polishing is performed while controlling the contact time at the position.

In the polishing apparatus and the polishing method as described above, since the spherical polishing surface of the polishing body is brought into contact with the object to be polished , spot contact is made. Therefore, even if the curved surface of the object to be polished is an aspherical surface, Polishing can follow the aspherical shape. Further, by controlling the contact time at each position on the object to be polished, a portion with a relatively long contact time is polished, and a portion with a relatively short length is polished. Creation of an aspheric shape is also possible. In addition, since the contact position and contact time can be controlled by controlling the swing of the workpiece (swing by the first swing mechanism), high-precision control is possible while simplifying the device structure. It becomes .

  Since the polishing tool and the object to be polished are brought into spot contact and the contact time on the object to be controlled can be controlled, even an aspherical surface can be polished with high accuracy, and further desired. It is also possible to create an aspherical shape. Furthermore, the apparatus structure can be simplified by adopting a method of swinging the polishing tool and the workpiece.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an overall view showing a schematic configuration of a polishing apparatus 1 for polishing a glass lens molding die and a glass lens molding die 2 fixed thereto, which is an embodiment of the present invention.
In the following description of the polishing apparatus 1, “upper” and “lower” when “upper”, “upward”, “lower”, “lower”, and the like are referred to It is assumed that “upper” and “lower” in a state where Y1 and the second oscillating portion Y2 are not inclined (that is, a state where a lower shaft body 4 and a polishing tool 7 described later are oriented in the vertical direction).

  The polishing apparatus 1 is roughly divided into a first swing part Y1 and a second swing part Y2 that are separate from each other. The first oscillating portion Y1 includes a first oscillating mechanism that oscillates with the first oscillating axis Z1 (indicated by a broken line in FIG. 1) as the oscillating center axis. The second oscillating portion Y2 includes a second oscillating mechanism that oscillates with the second oscillating axis Z2 (indicated by a broken line in FIG. 1) as the oscillating center axis.

  The first oscillating portion Y1 includes a disk-shaped fixing base 3 for fixing a glass lens molding die 2 as an object to be polished (work) and a lower shaft extending vertically downward from the center of the lower surface of the fixing base 3. A body 4 and a workpiece rotating motor M1 as a rotating mechanism for rotating the glass lens molding die 2 fixed to the fixed base 3 by rotating the lower shaft body 4 are provided. One end (upper end) of the lower shaft body 4 is attached to the fixed base 3, and the other end (lower end) is integrated with the rotation shaft of the work rotation motor M1.

  The first swinging portion Y1 further includes a vertical arm 13 that extends substantially in the vertical direction, a first arm 10 that extends in the horizontal direction from approximately the center in the longitudinal direction of the vertical arm 13 and that rotatably supports the lower shaft body 4. A second arm 11 that extends in parallel with the first arm 10 from the lower end of the vertical arm 13 and supports the work rotating motor M1, and a second arm that extends horizontally from the top of the vertical arm 13 and in a direction opposite to the first arm 10. A pendulum body 12 having a uniaxial body 5 is provided. The first arm 10, the second arm 11, and the vertical arm 13 are linear rod-shaped members having a rectangular cross section, and the first shaft body 5 is a circular cylindrical bar having a circular cross section, and these first arm 10, second arm 11, and The vertical arm 13 has an integral structure. The first shaft body 5 is rotated by a stepping motor (not shown).

  The first rocking portion Y1 includes a first rocking support portion 14 that rotatably supports the first shaft body 5. Although not shown, the first swing support portion 14 is fixed to the base portion of the polishing apparatus 1. Therefore, the 1st rocking | fluctuation support part 14 is supporting the 1st shaft body 5 so that rotation is possible, and is supporting the whole pendulum body 12 so that rocking | fluctuation is possible. When the pendulum body 12 swings, the fixed base 3, the lower shaft body 4, and the workpiece rotating motor M1 also swing integrally with the pendulum body 12. This swing is hereinafter referred to as a first swing Ya (see the arrow in FIG. 1).

  During the swinging of the first swinging portion Y1, the lower shaft body 4 is rotated by the rotation of the workpiece rotating motor M1, thereby rotating the disk-shaped fixing base 3 and thus being fixed to the upper surface of the fixing base 3. The glass lens molding die 2 also rotates. That is, the first swinging portion Y1 swings while rotating the glass lens molding die 2 as an object to be polished.

  On the other hand, the second oscillating portion Y2 includes a rod-shaped polishing tool 7 extending in the vertical direction and having a spherical polishing body 6 at one end (lower end). The polishing body 6 is made of a material such as tin suitable for precision polishing. Further, the second oscillating portion Y2 extends in the horizontal direction and has a third arm 15 having a polishing tool 7 at one end thereof, and a fourth arm 16 extending downward from the other end of the third arm 15 in parallel with the polishing tool 7. And having. Further, from the vicinity of the lower end of the fourth arm 16, the second shaft body 8 extends in a direction opposite to the third arm 15 and parallel to the third arm 15. The second shaft body 8 is a rod-shaped member having a circular cross section, and is rotatably supported by the second swing support portion 17. One end of the second shaft body 8 is integrated with the fourth arm 16, and the other end is connected to the second swing motor M <b> 2 via the rotation transmission unit 18. The second swing motor M2 is fixed to a base portion of the polishing apparatus 1 (not shown). The rotation of the second oscillating motor M2 that drives the oscillating movement of the second oscillating portion Y2 (hereinafter referred to as the second oscillating Yb or the like) is transmitted to the second shaft body 8 via the rotation transmitting portion 18. When the second swing motor M2 is rotated, the second shaft body 8 is rotated, and the polishing tool 7 including the polishing body 6, the third arm 15, and the fourth arm 16 are integrally formed. Rocks.

The rotation transmitting unit 18 extends linearly from the rotating shaft 19 on the second swing motor M2 side to a linear rod-like motor-side vertical arm 20 and extends horizontally from the top of the motor-side vertical arm 20 to the second shaft body 8 side. A linear bar-shaped transmission horizontal arm 21 and a linear bar-shaped second shaft body side vertical arm 22 extending upward from the end of the second shaft body 8 on the second swing motor M2 side are provided.
The motor-side vertical arm 20 and the transmission lateral arm 21 are fixed integrally with each other, but the transmission lateral arm 21 and the second shaft-body-side vertical arm 22 can move relative to each other in the vertical direction. That is, the second shaft body side vertical arm 22 includes a slit (gap) (not shown) extending along the longitudinal direction (vertical direction), and the transmission horizontal arm 21 is inserted into the slit without any gap. ing. When the relative positional relationship between the second shaft body 8 and the rotary shaft 19 changes, the transmission lateral arm 21 can move (slide) in the slit of the second shaft body side vertical arm 22. . Therefore, the rotation transmitting unit 18 transmits the shaft rotation of the rotating shaft 19 to the second shaft body 8 while allowing a relative position change (axial deviation) between the second shaft body 8 and the rotating shaft 19.

FIG. 2 is a view of the first swing axis Z1 (or the second swing axis Z2) as viewed from the direction of the extension line, and the first swing portion Y1 (swing integrally with the first swing Ya). Glass lens molding die 2, fixing base 3, lower shaft body 4, work rotating motor M <b> 1), and second swinging portion Y <b> 2 (polishing tool 7) swinging by the second swinging Yb. It is a figure which shows a rocking | fluctuation state. In FIG. 2, a state in which the lower shaft body 4 and the polishing tool 7 are oriented in the vertical direction is indicated by a solid line, and a state in which the lower shaft body 4 and the polishing tool 7 are swung left and right is indicated by a virtual line (two-dot chain line). In FIG. 2, the centers of the + marks on the glass lens molding die 2 and the polishing body 6 are the first swing axis Z1 and the second swing axis Z2, respectively.
As described above, when the first shaft body 5 is rotated by a stepping motor (not shown), the pendulum body 12, the lower shaft body 4 and the like swing with the first swing axis Z1 as the swing center axis. The mold 2 also swings while being inclined. On the other hand, when the second shaft body 8 is rotated by the second swing motor M2, the polishing tool 7 swings together with the third arm 15 and the fourth arm 16 with the second swing axis Z2 as the swing center axis.

  FIG. 4 is an enlarged perspective view of the vicinity of the glass lens molding die 2. The glass lens molding die 2 includes a cylindrical base portion k and a protruding portion t that protrudes in a hill shape upward from the upper end surface of the base portion k. This glass lens molding die 2 is used, for example, as an upper die or a lower die of a cylindrical barrel die and an upper die and a lower die inserted therein, and the shape of the protruding portion t is transferred to a molding material. This is for forming a concave lens. And the surface of the protrusion part t is the to-be-polished surface 2a used as grinding | polishing object.

The glass lens molding die 2 is fixed at the center position of a disk-shaped fixing base 3, and is arranged so that the center axis 2 </ b> Z coincides with the center axis RZ of the lower shaft body 4. Since the center axis RZ of the lower shaft body 4 is also a rotation axis by the work rotation motor M1, the glass lens molding die 2 rotates with the center axis 2Z as the rotation axis. And the protrusion part t of the metal mold | die 2 rotates around the center axis line 2Z, contacting with the polishing body 6 by spot contact. Therefore, relative movement occurs between the polishing body 6 and the surface to be polished 2a of the protrusion t, and polishing is performed. In addition, the contact area of the protrusion part t and the grinding | polishing body 6 is about 0.1 mm < ² > or less.
The protruding portion t has a spherical shape or an aspherical shape, but it is preferable that the protruding portion t has a uniform shape around the central axis 2Z of the base k at least after polishing. This is because polishing is performed while rotating the mold 2 around the central axis 2Z as described above. The uniform shape around the central axis 2Z means that a cross section by a plane perpendicular to the central axis 2Z becomes a circle centered on the central axis 2Z at any position in the longitudinal direction of the central axis 2Z. The polishing apparatus 1 is used for polishing not only a convex curved surface such as the polished surface 2a of the present embodiment but also a concave curved surface.

  As shown in FIGS. 1 and 2, the first swing axis Z1 and the second swing axis Z2 are different from each other, but they are parallel to each other and both are located in the same vertical plane. ing. The second swing axis Z2 is set to a position where the position (three-dimensional position) of the polishing body 6 hardly changes due to the second swing Yb. In the present embodiment, the second swing axis Z2 is set at a position passing through the inside of the polishing body 6. Further, the second swing axis Z2 passes through the center point (or the vicinity thereof) of the polishing body 6 which is a sphere. For this reason, as shown in FIG. 2, even if the polishing tool 7 is swung by the second swing Yb, the position (three-dimensional position) of the polishing body 6 is not changed. Even when the polishing body 6 is not a sphere, if the portion of the surface of the polishing body 6 that contacts the surface 2a to be polished is a spherical surface, it passes through the center of curvature of the spherical surface of the contact portion. If the second swing axis Z2 is disposed in the contact portion, it is preferable that the contact portion of the polishing body 6 is not moved by the second swing Yb.

  On the other hand, the first swing axis Z1 passes through the inside of the glass lens molding die 2, and the position (three-dimensional position) of the polished surface 2a of the glass lens molding die 2 by the first swing Ya. Has been made difficult to change. In addition, when the to-be-polished surface 2a is a spherical surface and this is polished while maintaining the spherical shape, or the to-be-polished surface 2a is a spherical surface and polished to create an aspheric shape. In this case, it is more preferable that the first oscillation axis Z1 passes through the center of curvature of the polished surface 2a (spherical surface) before or after polishing because the position of the polished surface 2a hardly changes. When the polished surface 2a has an aspherical shape, the first oscillation axis Z1 passes through the center of curvature of a spherical surface (any one of the spherical surfaces) constituting a part of the aspherical surface. Then, since the position of the to-be-polished surface 2a does not change easily, it is preferable.

  Since the configuration is as described above, the position of the surface 2a to be polished is hardly changed by the first swing Ya, and the polishing body 6 can be in contact with the surface 2a to be polished by the second swing Yb. The position of the (surface) hardly changes. Therefore, it is easy to perform rocking by the first rocking Ya and the second rocking Yb while maintaining the state in which the polishing body 6 and the surface 2a to be polished are in contact with each other.

  Then, as shown in FIG. 2, the glass lens molding die 2 is tilted while being swung by the first swing Ya, and the contact position between the surface to be polished 2 a of the glass lens molding die 2 and the polishing body 6. To change. That is, in the state J1 (the state where the lower shaft body 4 is directed in the vertical direction), the apex portion of the surface 2a to be polished and the polishing body 6 are in contact with each other, and the state J2 (the state of swinging rightward in FIG. In the state J3 (see the phantom line) in the state J3 (see the oscillating left direction in FIG. 2, see the phantom line). The left side portion (on FIG. 2) and the polishing body 6 are in contact.

  As described above, the position of the polishing body 6 hardly changes due to the second swing Yb, and the first swing axis Z1 and the second swing axis Z2 are in a parallel relationship. The glass lens molding die 2 is rotated around the central axis 2Z as described above, although it moves so as to cross the surface 2a to be polished substantially along one generatrix at the protruding portion t. The entire surface 2a to be polished is polished. However, in order to polish the whole surface 2a to be polished, it is necessary that the polishing body 6 passes through the apex of the protrusion t. For this reason, a position adjustment mechanism capable of finely adjusting the relative positional relationship between the first swing part Y1 and the second swing part Y2 is provided in the first swing part Y1 or the second swing part Y2. preferable.

  In order to polish the surface 2a to be polished by the polishing body 6, it is necessary to apply a predetermined pressure (hereinafter referred to as a polishing pressure) between them. In the polishing apparatus 1, the second swing support portion 17 that rotatably supports the second shaft body 8 is supported by a slide mechanism (not shown) so as to be slidable in the vertical direction. The second shaft body 8 supported by the second shaft body 8, and the weights of the third arm 15, the fourth arm 16, the polishing tool 7, etc. integrated with the second shaft body 8 are between the polishing body 6 and the surface 2 a to be polished. In this state, it acts as a polishing pressure. As described above, the second swing support portion 17, the second shaft body 8, and the like move up and down, and the vertical relative position between the second shaft body 8 and the rotation shaft 19 (on the second swing motor M <b> 2 side) is changed. Even if it changes, the rotation of the second swing motor M <b> 2 is transmitted from the rotation shaft 19 to the second shaft body 8 by the rotation transmission unit 18 described above. Note that the slide mechanism (not shown) also swings integrally with the second swing support portion 17 and the like by the second swing Yb.

  In addition, since the second swing support portion 17 and the like can be moved in the vertical direction as described above and the polishing pressure is applied by its own weight, the polishing body 6 can polish the surface 2a to be polished. Even if the surface 2a to be polished proceeds and is ground, it follows the surface 2a to be polished while maintaining the polishing pressure. Similarly, the polishing body 6 follows the surface to be polished 2a while maintaining the polishing pressure even if the surface to be polished 2a has an aspherical shape. Further, the reason why the polishing can follow the aspherical shape is that the contact between the polishing body 6 and the surface 2a to be polished is a spot contact.

  As described above, the polishing apparatus 1 includes a polishing pressure applying unit that can polish the polishing body 6 while following the surface 2a to be polished while applying a polishing pressure between the polishing body 6 and the surface 2a to be polished. The polishing pressure applying means is not limited to the above-described configuration. For example, the bending of each part of the first oscillating portion Y1 and the second oscillating portion Y2 such as the third arm 15 may be used, or A biasing means such as a spring for biasing the surface to be polished 2a or the polishing body 6 toward the other side may be provided between the polishing surface 2a and the polishing body 6 so as to generate a polishing pressure. Also, a vertical position adjustment mechanism that can finely adjust the relative positional relationship between the first swing part Y1 and the second swing part Y2 in the vertical direction is provided in the first swing part Y1 or the second swing part Y2. Accordingly, it is possible to easily realize the polishing pressure applying means by the above-described bending of each part.

In this embodiment, the first oscillating portion Y1 is oscillated at a relatively slow cycle of about 5 minutes, whereas the second oscillating portion Y2 is oscillated at a relatively fast cycle of about 1 second. Let Therefore, the contact position in Ken Migakukarada on 6 periodically moved, uneven wear of the abrasive member 6 is suppressed. Therefore, the change with time of the contact area between the polishing body 6 and the surface 2a to be polished is reduced, and the polishing accuracy is increased.

  The polishing apparatus 1 includes a swing control mechanism that controls the contact time at each contact position between the polished surface 2a and the polishing body 6 by controlling the swing of the first swing portion Y1. The swing control of the first swing portion Y1 is performed by the stepping motor that rotates the first shaft body 5. By using the stepping motor, it is possible to control the rotation angle of the first shaft 5 and the angular velocity at each rotation angle. As described above, in the present embodiment, the first oscillating portion Y1 is oscillated at a relatively slow period of about 5 minutes. For example, when a desired aspherical shape is to be created by polishing, this is required. The rocking speed of the first rocking part Y1 is finely controlled. In this embodiment, the first oscillating portion Y1 has a oscillating cycle of about 5 minutes, the second oscillating portion Y2 has an oscillating cycle of about 1 second, and is continuously polished for about 1 to 2 hours. The surface 2a to be polished of the mold 2 is polished with a polishing amount of about 1 μm to several μm.

FIG. 3 is a view for explaining the swing control of the first swing portion Y1 by the swing control mechanism. Here, a description will be given of the swing control for obtaining the desired aspherical shape H by polishing the protruding portion t that originally had the spherical shape Q (broken line in FIG. 3).
In FIG. 3, the polishing tool 7 and the polishing body 6 are shown smaller than the mold 2 for the sake of clarity. Further, the polishing tool 7 and the polishing body 6 are moved on the protruding portion t by swinging and tilting the mold 2 as described above. However, for the sake of clarity, the polishing tool 7 and the polishing body 6 are as if they were fixed. It is described that the polishing tool 7 and the polishing body 6 have moved on the protrusion t.

In order to obtain a desired aspherical shape H from the spherical shape Q before polishing, it is necessary to continuously change the polishing amount d at each position on the protrusion t. Therefore, as the polishing body 6 moves from the vicinity α of the top of the protrusion t to the vicinity β of the protrusion t and further to the vicinity γ thereof, the angular velocity of the first swing Ya is gradually decreased (continuously). . When the angular velocity of the first swing Ya is relatively high, the residence time at the same position of the polishing body 6 is relatively short, and the polishing amount d can be relatively small. If the angular velocity of the first swing Ya is relatively slow, the residence time of the polishing body 6 at the same position is relatively long, and the polishing amount d can be relatively large. As described above, a desired shape can be created simply by controlling the angular velocity of the first oscillating portion Y1, so that the polishing apparatus 1 capable of creating a highly accurate shape is realized with an extremely simple apparatus structure. it can.
Note that the relative movement speed between the polishing body 6 and the protrusion t increases as the distance from the central axis 2Z, which is the rotation center axis of the mold 2, increases. Is controlled.

1 is an overall view showing a schematic configuration of a polishing apparatus for polishing a glass lens mold according to an embodiment of the present invention. It is a figure which shows the rocking | fluctuation state of a 1st rocking | swiveling part and a 2nd rocking | swiveling part seen from the extension line direction of the 1st rocking | fluctuation axis. It is a figure for demonstrating rocking | fluctuation control of the 1st rocking | swiveling part by a rocking | fluctuation control mechanism. It is an expansion perspective view of the mold for glass lens molding.

Explanation of symbols

1 Polishing device 2 Glass lens mold (Polished object)
6 Polishing body 7 Polishing tool Y1 First swing part (first swing mechanism)
Ya first swing Y2 second swing part (second swing mechanism)
Yb second swing

Claims (2)

A rotation mechanism for rotating the workpiece;
Polishing body having a spherical polishing surface is fixed to the lower end, the subject by Rukoto spot manner is brought into contact with the upper surface of the workpiece to rotate the spherical abrasive surface of the abrasive member by said rotary mechanism A rod-shaped polishing tool for polishing the upper surface of the polished object;
A first oscillating mechanism comprising a first oscillating support portion for oscillating the rotating mechanism while inclining so that the contact position between the object to be polished and the polishing body changes;
A second swing support portion for swinging the polishing tool about an axis passing through the center of curvature of the spherical polishing surface or the vicinity thereof in a state where the object to be polished and the polishing body are in contact with each other; A second swing mechanism,
A swing control mechanism capable of controlling a contact time at each contact position on the object to be polished by controlling swing by the first swing mechanism;
A curved surface polishing apparatus comprising: A polishing method in which polishing is performed by rotating the polishing object in a state where the polishing object having a spherical polishing surface and the polishing object are in spot contact with each other,
While the object to be polished and the polishing surface of the polishing body are in contact, the object to be polished is swung around an axis passing through the center of curvature of the spherical polishing surface or the vicinity thereof. While performing the polishing by changing the contact position of the object to be polished with respect to the polishing body by swinging ,
A curved surface polishing method, wherein polishing is performed while controlling a contact time at each contact position on the object to be polished by controlling the swing of the object to be polished.

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