JP4521359B2 - Polishing method and polishing apparatus - Google Patents

Description

  The present invention relates to a polishing method and a polishing apparatus for performing surface finishing of a lens or an optical element such as a prism made of a brittle material such as glass.

  As polishing technology for surface finishing of optical elements such as lenses, prisms, mirrors, etc., an object to be polished (for example, “lens”) and an elastic tool for polishing (pitch, polyurethane pad and polisher are shown. A polishing method is used in which the lens surface is removed with a polishing abrasive grain present at the interface. This polishing method is not limited to lenses but is also used for processing glass panels of display devices such as semiconductors, glass hard disks, and liquid crystal televisions.

  As described above, in the polishing method in which the object to be polished is worn by pressurization and processing, there are many manufacturing forms that depend on the skill of the operator for ensuring the shape accuracy of the polishing surface. . In particular, since it is difficult to polish evenly, that is, to promote the wear of the object to be polished uniformly, for example, a pressure method as shown in Patent Document 1 is adopted for an object to be easily deformed. A polishing apparatus has been proposed.

  In Patent Document 1, as shown in FIG. 5, it is disclosed that a polishing machine 101 performs a polishing process while sandwiching an object to be polished 102 that is a flat object from both the front and back surfaces by using fluid pressure. . That is, the polishing machine 101 has upper and lower surface plates 104, 105 facing each other, and has a polishing pad 106 at the opening of the hollow portion 103 of the upper surface plate 104. In addition, a sheet-like holding material 108 is provided in the opening of the hollow portion 107 of the lower surface plate 105, and the workpiece 102 is disposed between the holding material 108 and the polishing pad 106.

  Further, a pressurized fluid is supplied into the hollow portions 103 and 107, and the polishing pad 106 and the workpiece 102 are elastically stretched to support the floating. Then, while supplying the slurry, the polishing pad 106 and the workpiece 102 are moved relative to each other to polish the workpiece 102.

  According to the polishing machine 101, the object to be polished 102 is clamped from both sides by using fluid pressure, so that an equal polishing load can be applied to the object to be polished 102, and a highly accurate polishing surface by uniform wear can be obtained. It can be obtained.

Next, although there is a difference from the object of the present invention, the present applicant has previously proposed the technique described in Patent Document 2 as similar prior art.
This Patent Document 2 discloses a grinding method and apparatus. According to this polishing method, as shown in FIGS. 6 (a) and 6 (b), in the process of manufacturing a glass lens, a processing step (creating step) for creating a spherical shape on the workpiece 112 by the cup-type grinding tool 111; In order to improve the accuracy of the created spherical shape, grinding processing (finishing step) for finishing the spherical surface with the total grinding tool 113 is performed by the same machine.

Specifically, the creation step includes a step of holding the workpiece 112 by the collet chuck 114 and a step of moving the cup-type grinding tool 111 relative to the workpiece 112 by the tool shaft portion for grinding. In addition, the finishing step includes a step of pressurizing the workpiece 112 and grinding the total type grinding tool 113 disposed concentrically with the cup type grinding tool 111 by swinging the tool shaft portion. And in order to perform a creation process and a finishing process with the same machine, the cup type grinding tool 111 and the total type grinding tool 113 are arrange | positioned, and it processes by switching to each process.
JP 2004-74399 A (page 8, FIG. 3) JP-A-7-164297 (page 3, FIG. 1)

  However, the technique disclosed in Patent Document 1 is an effective polishing method for a thin plate-like object having both the front and back surfaces of the object to be polished 102 having a planar shape, but the target is limited to the object having a planar shape. Will be. Therefore, for example, the object to be polished 102 has a spherical shape such as an optical lens, or the thickness is different in the radial direction or the vertical and horizontal directions of the object 102 to be polished. This is because it is difficult to elastically stretch the polishing pad 106 or the holding material 108 to which fluid pressure is applied so as to contact the surface to be polished 102 uniformly.

  Further, in the technique described in Patent Document 1, in a state where the object to be polished 102 is sandwiched between the polishing pad 106 and the holding material 108, the polishing pad 106 and the object to be polished 102 are moved relative to each other while further slurry is being supplied. Need to do. For this reason, it is difficult for the pad surface swollen by the fluid pressure to keep the spherical shape following the relative movement, and high polishing surface accuracy cannot be obtained.

  In the technique described in Patent Document 1, high-precision polishing is performed by uniformly pressing the workpiece 102 while preventing the thin plate-like workpiece 102 from being deformed by the pressure applied in the polishing process. We are carrying out. For this reason, it is difficult to cope with an object to be polished having a spherical shape, and uneven wear due to the relative velocity distribution between the polishing pad 106 and the object to be polished 102 generated in the polishing process has not been solved.

  Further, the technique described in Patent Document 2 is based on the cup-type grinding tool 111 used in the creation process and the total mold used in the finishing process in order to realize the creation process and the finishing process when the optical lens is originally manufactured by the same machine. The grinding tool 113 is arranged in the same machine, and the machining is performed by switching to each process. That is, this prior art is not a means for achieving high accuracy of polishing and reducing the dependence on the skill of the operator.

  The present invention has been made to solve such a problem, and the object of the present invention is to process an object to be polished (work) with high shape accuracy and polishing surface accuracy without requiring skilled skills. It is an object of the present invention to provide a polishing method and a polishing apparatus that can perform the same.

In order to achieve the object, the invention according to claim 1
In a polishing method in which the rotation axis of a polishing dish is inclined with respect to the rotation axis of the work and the workpiece is brought into contact with and pressed against the polishing dish, and the work is polished by moving the workpiece and the polishing dish relative to each other.
The workpiece is held so as to be rotatable and tilted, the tiltable support of the polishing dish is fixed and the workpiece is brought into contact with the polishing dish, and polishing is performed by relative rotational movement and swinging movement of the workpiece and the polishing dish. A first polishing step for processing;
A second polishing step of holding the polishing dish so as to be capable of rotating and tilting, fixing the tiltable support of the work and subsequently performing a polishing process by a relative rotational movement and swinging movement of the work and the polishing dish; It is characterized by having.

The invention according to claim 2 is the polishing method according to claim 1,
When shifting to the second polishing step, polishing is performed with the inclination being smaller than the angle at which the polishing dish is inclined in the first polishing step.

The invention according to claim 3 is the polishing method according to claim 1,
When shifting to the second polishing step, the polishing plate is disposed with an inclination smaller than the angle at which the polishing plate is inclined in the first polishing step, and polishing is performed while transmitting rotational power to the polishing plate. It is characterized by performing.

The invention according to claim 4
A polishing apparatus in which a rotation axis of a polishing dish is inclined with respect to a rotation axis of the work, the work is brought into contact with the polishing dish and pressurized, and a relative motion is applied to the work and the polishing dish to polish the work. In
A first chuck means for holding the workpiece in a rotationally tiltable manner and fixing a tiltable support of the workpiece;
A second chuck means for holding the polishing dish so as to be capable of rotating and tilting and fixing the tilting support of the polishing dish;
The second chuck means fixes the tiltable support of the polishing dish in a state where the work is supported so as to be rotatable and tiltable.
The first chuck means fixes the tiltable support of the workpiece in a state where the polishing dish is supported so as to be rotatable and tiltable.

  According to the present invention, in order to achieve high-precision polishing, the work and the polishing plate are turned upside down by continuously and automatically performing the work upside down on the machine to reduce the polishing speed of the work. Therefore, it is possible to perform processing with high shape accuracy and polished surface accuracy without depending on the operator.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1A shows the state of the first polishing process by the polishing apparatus M. FIG. In addition, a schematic diagram of a load distribution section 22 of a polishing load acting on the lens 3 as an object to be polished and a shape section 23 of the lens 3 obtained thereby is shown below FIG.

  FIG. 1B shows the state of the second polishing process. In addition, a schematic diagram of a load distribution section 24 of a polishing load acting on the lens 3 and a shape section 25 of the lens 3 obtained thereby is shown below FIG.

  In FIG. 1 (a), the lens 3 is mounted on the upper shaft unit 1, the polishing dish 5 is mounted on the lower shaft unit 2, and a relative motion is performed in which they are rubbed against each other. Specifically, the lens 3 is polished by the axial rotation movements 18 and 19 of the lens 3 and the polishing dish 5 and the swinging movement 20 of the polishing dish 5.

  Note that in the polishing apparatus M of the present embodiment, the illustration of the mechanical part of the existing polishing apparatus is omitted. In the present embodiment, the lens 3 and the upper shaft unit 1 and the lower shaft unit 2 excluding the polishing dish 5 for polishing the lens 3 basically have the same configuration.

  First, in the first polishing step, the lens 3 that is an object to be polished is fitted or adhered and held in the holder 4. The holder 4 has a fitting portion that approximates the diameter of the lens 3 on the surface side, and a concave spherical surface portion that fits on the spherical surface at the tip of the upper shaft body 6 on the anti-lens 3 surface side. is doing. A pressing force is applied to the holder 4 via the upper shaft assembly 6.

  Thereby, the lens 3 is brought into contact with the polishing dish 5 with a predetermined pressure. At this time, since the upper shaft body 6 and the holder 4 are spherically in contact with each other, the holder 4 (that is, the lens 3) is supported so as to be inclined and rotatable with respect to the upper shaft body 6.

  The upper shaft cylinder 6 has an upper shaft cylinder 7 connected to the opposite side of the spherical surface portion, and air is supplied to the upper shaft cylinder 7 from a pneumatic supply device (not shown) or the like. Then, a polishing load is applied to the lens 3 through the upper shaft body 6 and the holder 4 by this air pressure.

  The upper shaft body 6 is mounted on an upper shaft chuck 10 as first chuck means that can be freely opened and closed and can hold the holder 4. The upper shaft chuck 10 is attached to a rotating upper shaft spindle 12 through a bearing and the like together with the upper shaft cylinder 7. When the upper shaft chuck 10 is closed, the holder 4 can be clamped.

An upper shaft motor 14 as a driving means is connected to the upper shaft spindle 12, and thereby the upper shaft spindle 12 is rotatably supported.
Further, the lower shaft unit 2 on which the polishing dish 5 is mounted has the same structure as the upper shaft unit 1 described above. That is, the lower shaft unit 2 sandwiches the polishing plate 5 so that the polishing plate 5 is tilted and rotatably supported, the lower shaft cylinder 9 that presses the lower shaft mounting 8 toward the polishing plate 5 side, and the polishing plate 5 is opened and closed. A lower shaft chuck 11 is provided as second chuck means.

  Further, the lower shaft chuck 11 is connected to a lower shaft spindle 13 for rotating and supporting the lower shaft chuck 11 and the like, and a lower shaft motor 15 as a driving means for rotating the lower shaft spindle 13.

  Further, the control device 16 controls the upper shaft cylinder 7, the upper shaft chuck 10, the upper shaft motor 14, the lower shaft cylinder 9, and the lower shaft so that the operations of the upper shaft unit 1 and the lower shaft unit 2 are synchronized. The chuck 11 and the lower shaft motor 15 are electrically connected.

  In the polishing method of this embodiment, as shown in FIG. 1A, the polishing dish 5 is mounted in advance at a position suitable for the lens 3, and the lens 3 is fitted or adhered to the holder 4. In addition, the upper shaft chuck 10 is closed and the holder 4 is held in a state where the holder 4 is applied to the upper shaft body 6. Further, the lens 3 is brought into contact with the polishing dish 5 while lowering the upper shaft unit 1. At this time, the upper shaft chuck 10 is opened almost simultaneously with the contact of the lens 3 with the polishing dish 5, and the chuck of the holder 4 is released. As a result, the lens 3 can be tilted about the spherical surface portion of the upper shaft 6.

  The holder 4 is supported in a state in which the polishing dish 5 is pressed through the upper shaft body 6 by the air pressure from the upper shaft cylinder 7. At this time, the lower shaft chuck 11 is in a closed state, and the polishing plate 5 is sandwiched so that the polishing plate 5 does not tilt together with the lower shaft pindle 13. In this state, the lens 3 and the polishing dish 5 are subjected to predetermined upper shaft rotation motion 18, lower shaft rotation motion 19 and swing motion 20 to polish the lens 3. At this time, even if the upper shaft rotational motion 18 is not performed, the lens 3 moves along with the lower shaft rotational motion 19 of the polishing dish 5. For this reason, it is not always necessary to apply the driving force by the upper shaft motor 14. Details regarding the rotational motion will be described later.

  The process and state described above are substantially the same as the state in which the existing lens polishing machine makes the lens 3 abut on the polishing dish 5 and performs polishing. Then, after the polishing process progresses in this state, the process proceeds to the process of FIG. 1B, which is the second polishing process.

  Specifically, the upper shaft chuck 10 is closed and the lower shaft chuck 11 is opened by a signal (command) from the control device 16, and the pressure applied from the upper shaft cylinder 7 is interlocked with the opening and closing of the upper and lower chucks. A certain upper shaft load (arrow direction) P is decreased. At the same time, the pressing force Q of the lower shaft cylinder 9 is increased, and the pressure shaft is switched from the upper shaft unit 1 to the lower shaft unit 2.

  As a result, as shown in FIG. 1A, the polishing dish 5 is sandwiched and the lens 3 is sandwiched as shown in FIG. The lens 3 shifts to a state in which the lens 3 is pressurized from the polishing dish 5.

Next, the operation when shifting from the first polishing step to the second polishing step will be described.
In the first polishing step, polishing is performed by relative movement with the polishing dish 5 while the lens 3 is pressed and held by the upper shaft knuckle 4 so as to be tiltable and rotatable. In this configuration, since the load P is applied from the lens 3 side toward the polishing dish 5, the direction of the load P is always applied only in the direction of the central axis of the upper shaft pattern 6 (ie, the lens 3). This is because the load P is always applied to the central axis of the lens 3 regardless of the position of the polishing plate 5 that is moved by the relative movement of the lens 3 and the polishing plate 5, that is, the swinging movement 20 of the polishing plate 5. Will be.

  Therefore, in the first polishing process, the load P applied to the lens 3 is always in the same direction at any relative position during the polishing process. For this reason, the same load distribution 22 is always added to the lens 3, and uneven wear corresponding to the load distribution 22 is generated. In this case, even if the relative positions of the lens 3 and the polishing dish 5 are changed, the magnitude of the pressure according to the change in the contact area between the two changes, but the pattern of the load distribution 22 does not change.

  For this reason, uneven wear corresponding to the pattern of the load distribution 22 occurs at any relative position between the lens 3 and the polishing dish 5. Thereby, the lens cross-sectional shape 23 shown in FIG. 1A is generated, and it is difficult to ensure high spherical accuracy.

  Specifically, the load P is always applied from the central axis of the lens 3 that is supported so as to be tilted via the upper shaft body 6. For this reason, the lens 3 is turned over to the surface side that is not in contact with the polishing dish 5 with a boundary point 21 that does not come into contact with the polishing dish 5 as the fulcrum moves relative to the polishing dish 5. A moment to try is generated. A load distribution section 22 in which stress is concentrated at the boundary point 21 is always generated. For this reason, the amount of wear at this portion is maximized (see the lower view of FIG. 1A).

  Further, since the boundary point 21 is a boundary where the lens 3 does not come into contact with the polishing dish 5, the boundary point 21 is the outermost peripheral portion of the polishing dish 5, and this is the peripheral speed of rotation accompanying the lower shaft rotation 19 of the polishing dish 5. Therefore, the relative speed is the highest together with the load, and the wear of the lens 3 is particularly advanced.

  For this reason, when polishing is performed in the state shown in FIG. 1A as seen in a conventional polishing machine, uneven wear always occurs in the vicinity of the boundary point 21 between the lens 3 and the polishing dish 5. Then, as the cross-sectional shape of the lens 3, as shown in the lens cross-sectional shape 23 in the lower part of FIG. 1A, the intermediate portion between the central axis of the lens 3 and the outer periphery thereof is worn a lot.

  For this reason, so-called medium and high in lens polishing (the center of the lens is less worn compared to other parts), or edge (the outer periphery of the lens (= edge) is more worn than other parts) Thus, the lens 3 has a low spherical accuracy.

  However, in the first polishing step, the spherical shape accuracy is reduced due to uneven wear in the polishing surface, but on the other hand, the high load region and the high relative velocity region almost coincide with each other, so that a high polishing rate can be secured. This is a polishing method with high cost merit. For this reason, this polishing technique is often used in mass-production lenses that do not require high spherical accuracy.

Next, in the second polishing step with respect to the first polishing step, the arrangement of the lens 3 and the polishing dish 5 is the same, but the support state of both and the direction in which the polishing load is applied are changed.
In this second polishing step, the basic configuration is the same as in the first polishing step. However, the holder 4 supported by the upper shaft body 6 so as to be tiltable and rotatable in the first polishing step is clamped by the upper shaft chuck 10 in the second polishing step. At the same time, the polishing plate 5 held in the first polishing step is opened and supported by the lower shaft body 8 so that the tilting needle can rotate. Further, the polishing load P is also transmitted to the polishing dish 5 from the direction of the lower shaft tension 8 in the second polishing step, and the upper and lower states are reversed from those in the first polishing step.

  That is, in the first polishing process, the lens 3 is supported so as to be tiltable and the polishing load P is applied from the upper shaft unit 1 side having the lens 3. However, in the second polishing step, the lens 3 is sandwiched and held, and the lower shaft load Q is applied from the lower shaft unit 2 having the polishing dish 5 in a state where the degree of freedom is lost. For this reason, the load distribution cross section 24 generated in the lens 3 changes, and the wear of the lens 3 is changed to achieve high accuracy.

  What is important here is that the state of the first polishing process, that is, even if the load is switched to the lower shaft load 28 while the lens 3 can be tilted and rotated and the polishing plate 5 is held, it is the law of action and reaction. Accordingly, there is no change from the first polishing state.

  Therefore, in order to switch the load direction, it is important to switch the upper and lower degrees of freedom. Thus, when the lower shaft load Q is applied to the lens 3, unlike the first polishing step, the lower shaft load Q is applied to the lens 3 from the central axis direction of the polishing dish 5. For this reason, the direction in which the lower shaft load Q is applied to the lens 3 always changes according to the swinging motion 20 that is a relative motion between the lens 3 and the polishing dish 5.

  In this way, it is difficult to obtain a single load distribution 22 as generated in the first polishing process, and it is possible to correct a decrease in shape accuracy generated particularly in the first polishing process. At the same time, in the second polishing process, since the lens 3 is sandwiched and cannot be tilted, a high load is not applied due to the stress concentration on the lens 3 at the boundary point 21, and a load distribution section 24 corresponding to the direction of the lower shaft load Q is obtained. be able to.

  However, in the second polishing process, since the lower shaft load Q is applied to the lens 3 from the central axis direction of the polishing dish 5, unlike the first polishing process, the load on the lens 3 rotates most of the polishing dish 5. Distributes with maximum load at the center of small speed. For this reason, the position where the load is large and the position where the speed is high do not coincide with each other, and the polishing speed becomes slow.

For this reason, there is a disadvantage for a lens 3 in which shortening the polishing time greatly affects the cost, such as a mass production lens.
Therefore, in this embodiment, the first polishing step effective for the polishing rate and the second polishing step effective for the polishing accuracy are integrated and combined to combine the advantages of both. This is a polishing method.

  Specifically, until the mirror surface (surface roughness) required by the polishing process is obtained for the lens 3, the first polishing step having a high polishing rate is performed, and the mirror surface remains on the polishing surface when the mirror surface is obtained. In order to eliminate uneven wear, a highly accurate polished surface can be obtained in a short time by removing minute errors in the second polishing step.

That is, according to the present embodiment, the lens 3 and the polishing dish 5 are turned upside down according to the state of the process in the work that a skilled polishing worker is performing empirically to increase the accuracy of the polishing surface. Thus, it is possible to automate the polishing operation and perform high-precision polishing.
(Second Embodiment)
2 and 3 are diagrams showing a second embodiment of the present invention.

The polishing procedure is shown in FIG. 2, and the principle is explained in FIG.
In the present embodiment, even if the polishing in the second polishing step for increasing the spherical accuracy and shape accuracy of the lens 3 is performed, the change in the radius of curvature, which is a spherical shape, is suppressed. In addition, about the member which is the same as that of FIG. 1 (a) (b) mentioned above or corresponds, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

FIG. 2A shows the first polishing step, and the configuration is the same as FIG. In FIG. 2A, for the sake of convenience of explanation, in order to polish the polishing dish 5 and the lens 3 by relative movement, the angle at which the polishing dish 5 is inclined is defined as a first relative angle θ ₁ . Further, in order to polish the lens 3, the lens 3 and the polishing dish 5 each rotate, and the first relative angle θ ₁ is an angle formed by the lens rotating shaft 30 and the polishing dish rotating shaft 31.

Next, FIG. 2B shows a second polishing step, and the configuration is the same as FIG.
Similarly to FIG. 2A, the angle formed by the lens rotation shaft 30 and the polishing plate rotation shaft 31 to incline the polishing plate 5 is defined as a second relative angle θ ₂ .

In the present embodiment, for the first relative angle theta ₁ which is set in the first polishing step, the second relative angle theta ₂ in the second polishing step, smaller than the first relative angle theta ₁ And polish.
First, in the first polishing step of FIG. 2A, the upper shaft chuck 10 is opened, and the lens 3 is supported by the Kanzashi 6 so as to be tilted and rotatable. Further, the polishing dish 5 is clamped and held by the lower shaft chuck 11.

At this time, in order to polish the lens 3 with high accuracy, the polishing dish 5 is inclined at the first relative angle θ ₁ calculated in advance, and the lens 3 is pressed against the polishing dish 5. Accordingly, the lens is caused by the relative swinging motion 20 of the polishing dish 5, the lower shaft rotation 19 by the lower shaft motor 15, and the upper shaft rotation 18 that rotates around the rotation of the polishing dish 5 by the lower shaft rotation 19. 3 is polished.

  Next, when the mirror surface which is the polishing surface of the lens 3 is obtained by the first polishing step, the process proceeds to the second polishing step shown in FIG. In the second polishing step, the configuration is the reverse of that of the first polishing step, as described with reference to FIG. First, the lens 3 that is supported so as to be tiltable and rotatable is sandwiched by the upper shaft chuck 10 and its movement is fixedly held.

  Next, the polishing dish 5 sandwiched between the lower shaft chucks 11 is supported by the lower shaft body 8 so as to be inclined and rotatable as the lower shaft chuck 11 is opened. At this time, the lens 3 and the polishing dish 5 are implemented in a state where they are in contact with each other, as in the first polishing step.

The upper shaft load P is switched to the lower shaft load Q along with the opening and closing operations of the upper and lower chucks. Along with this change of load, in order to carry out the second polishing step, the lower shaft unit 2 turns so as to have a _second relative angle θ ₂ calculated in advance. Then, after the polishing dish 5 moves to the second relative angle θ ₂ , the rotational movement 18 of the lens 3 by the driving force of the upper shaft motor 14, the rotational movement 19 of the polishing dish 5 that moves around the lens 3, and the polishing dish 5 A swing motion 20 is performed. Then, the second polishing step is performed in order to remove the polishing error generated in the first polishing step.

Next, the operation and principle of the above-described embodiment will be described.
First, in the first polishing step, in order to polish the lens 3 with high accuracy by the polishing dish 5, the polishing dish 5 is arranged to be inclined at the _first relative angle θ ₁ . The first relative angle θ ₁ is calculated based on the shapes of the polishing dish 5 and the lens 3 shown in FIGS. 3 (a) and 3 (b), respectively.

In this case, in the polishing in which wear processing is performed by co-rubbing by the relative movement of the polishing dish 5 and the lens 3, the wear pattern, that is, the shape of the lens cross section 23 shown in FIG. The first relative angle θ ₁ is set as the position.

Specifically, the curvature radius R is shaped to have a lens 3 shown in FIG. 3 (b), based on the lens half-width β determined from both the lens diameter D _2, whose magnitude will be determined. Here, the radius of curvature R is a spherical radius to be created in the lens 3, and the lens diameter D ₂ means the diameter of the lens 3 to be polished.

The lens half angle β is an angle formed by a line connecting the central axis of the lens 3, the outer peripheral end of the lens diameter D ₂ and the center of the curvature radius R, and is also referred to as the “depth” of the lens 3. With respect to the lens half angle β, the polishing dish half angle α of the polishing dish 5 to be used is determined by the coefficient ratio. At this time, normally, in the polishing process of the lens 3, the polishing dish half angle α of the polishing dish 5 is set to a half angle larger than the lens half angle β.

This is because the polishing dish 5 is also worn because the polishing process is a co-rubbing process between the lens 3 and the polishing dish 5.
On the other hand, since suppressing the wear of the polishing dish 5 as much as possible affects the stabilization of polishing quality and the efficiency of manufacturing operations, it is common to use a polishing dish 5 larger than the lens 3. Further, it better to use a large grinding disc 5 are polished Sara径D ₁ as possible to suppress the wear of the polishing dish 5, with stable quality can be obtained, it is possible to obtain a high polishing rate.

And setting the _1st relative angle (theta) ₁ from which the shape of the lens cross section 23 is stably obtained using the polishing dish 5 which has the polishing dish half angle (alpha) larger than the lens half angle (beta) is that the polishing dish 5 is set. It is determined by the polishing dish half-angle α. At this time, the larger the polishing dish half angle α is, the larger the first relative angle θ ₁ is, and the first relative angle θ ₁ is set in proportion to the size of the polishing dish half angle α.

  This is fixed by the lower shaft chuck 11 in contrast to the lens 3 that is supported by the upper shaft body 6 so as to be tiltable and rotatable, following the polishing plate 5 using its degree of freedom. This is because the size of the polishing dish 5 that dominates the lens cross section 23 that becomes the wear pattern.

Next, when the process proceeds to the second polishing step shown in FIG. 2B, the principle described above works in the same manner. Therefore, in the second polishing step, the size of the lens half angle β which is the shape of the lens 3 fixed by the upper shaft chuck 10 determines the second relative angle θ ₂ for inclining the polishing dish 5.

  That is, in the second polishing step, the arrangement of the lens 3 and the polishing blood 5 is the same as that in the first polishing step, but since the pressurized state and the restrained state are reversed, it is as if the lens 3 has been polished so far. Acts as if it served the role of the dish 5.

That is, the configuration is similar to a state in which the large lens 3 is polished by the small polishing dish 5. For this reason, in the first polishing step, the polishing dish half angle α determines the first relative angle θ ₁ for performing stable polishing, whereas in the second polishing step, the lens half angle β. Will determine this.

Here, in this embodiment, from the first polishing step to the second polishing step, the lens 3 and the polishing dish 5 remain the same, and the steps are continuously switched to perform polishing. For this reason, in the second polishing step, it is necessary to set the relative angle θ ₂ as if polishing with a small polishing dish 5. For this reason, in the second polishing step, the relative angle θ ₂ is smaller than the first relative angle θ ₁ .

Therefore, in order to stably obtain the radius of curvature R of the lens 3 from the first polishing step to the second polishing step, the first relative angle θ ₁ determined by the polishing pan half angle α is changed to the lens half angle β. It is necessary to switch to the second relative angle θ ₂ determined in step (2). As long as the polishing dish half angle α is larger than the lens half angle β, the second relative angle θ ₂ needs to be set smaller than the first relative angle θ ₁ .

Here, the purpose of switching the first and second relative angles θ ₁ and θ ₂ in each polishing step is to stably obtain the curvature radius R to be created in the lens 3. However, this is not the case when it is necessary to change this dimension or to greatly correct the lens cross section 23 obtained in the first polishing process. Moreover, the above-described gist is to continuously carry out a stable polishing process through both the first polishing process and the second polishing process.

  In the second polishing step, it has been described that the lens half angle β is dominant in performing stable polishing, but this only reduces the changes in the lens cross section 23 and the curvature radius R of the lens 3. This is because the polishing is stably performed. For this reason, the lens 3 does not play the role of the polishing dish 5, but it is clear that the polishing action itself is manifested by the material of the polishing dish 5 and the like, and it is assumed that it is responsible for determining the physical position of both. Is.

According to this embodiment, when shifting from the first polishing step to the second polishing step, it is possible to perform polishing continuously while suppressing a change in the radius of curvature of the lens 3.
(Third embodiment)
FIG. 4 shows a second polishing step in the third embodiment. In the figure, members that are the same as or correspond to those in the above-described embodiment are given the same reference numerals, and descriptions thereof are omitted.

  In the present embodiment, in order to achieve higher polishing accuracy in the second polishing step, the rotational power is transmitted to the polishing dish 5 that is tilted and turned freely by being held by the lower shaft chuck 11. It is a thing. As a result, the polishing dish 5 is in a more stable wear state.

  In the present embodiment, an upper shaft pin 38 and a lower shaft pin 39 are embedded in each of the upper shaft body 6 and the lower shaft body 8 in a direction substantially orthogonal to the axial direction of each body body 6, 8. The holder 4 and the polishing dish 5 that hold the lens 3 are provided with notches 40 and 41 that support these pins 38 and 39. The holder 4 is configured to always transmit the rotation 18 of the upper shaft unit 1 including the upper shaft body 6 via the upper shaft pin 38. Further, the polishing dish 5 is configured to always transmit the rotation 19 of the lower shaft unit 2 including the lower shaft body 8 via the lower shaft pin 39.

  As described above, in the second polishing step, the lens 3 that is supported so as to be tiltable and rotatable until the first polishing step is restrained as the upper shaft chuck 10 is clamped in the second polishing step. On the contrary, the polishing dish 5 is supported so as to be inclined and rotatable in the second polishing step.

For this reason, in the second embodiment described above, in order to stably obtain the radius of curvature R of the lens 3 by polishing, the second relative angle θ ₂ at which the lens half angle β is the physical polishing position is determined. Explained. The situation is the same also in the present embodiment, and this state is obtained in the second polishing step shown in FIG.

The second relative angle θ ₂ is determined by the lens half angle β, and the polishing dish 5 may be inclined and moved to that position. However, unlike the first polishing step, a polishing dish 5 having a polishing dish half angle α larger than the lens half angle β, that is, a polishing dish 5 larger than the lens 3 is supported via the lower shaft body 8 so as to be tiltable and rotatable. ing.

  Therefore, in the configuration shown in the first embodiment, even if the lower shaft rotation 19 is transmitted by the lower shaft motor 15 via the lower shaft spindle 13, the polishing dish 5 is sandwiched in the second polishing step. Therefore, the rotational force is not transmitted. That is, the lower shaft motor 8 slides on the spherical surface at the tip portion, and the rotational force of the lower shaft motor 15 does not cause the polishing dish 5 to rotate.

  However, in reality, contrary to the first polishing step, the lens 3 disposed on the upper shaft unit 1 is sandwiched by the upper shaft chuck 10, so that the rotational power of the upper shaft motor 14 is transmitted to the lens 3. Then, the rotational force is transmitted to the polishing dish 5 being pressed and rotates together.

  For this reason, in the first embodiment, there is no problem in performing the polishing process. However, in order to obtain a higher accuracy of the polished surface, both of the polishing processes are performed for the relative polishing process including the rotational movement. It is preferable to control the rotation of the shaft.

  In particular, in the second polishing step, the holding state of the lens 3 and the polishing dish 5 is reversed, as opposed to the case of the first polishing process. Must-have. For this reason, the rotation error of the polishing dish 5 accompanying the change in the position of the swing 20 of the polishing dish 5 increases.

  In the present embodiment, when the lens 3 is pressed against the polishing dish 5, the upper shaft pin 38 attached to the upper shaft body 6 is mounted so as to be engaged with the notch 40 provided in the holder 4. Yes. Similarly, the polishing plate 5 is also installed so that the lower shaft pin 39 attached to the lower shaft assembly 8 fits into the notch 41 of the polishing plate 5. For this reason, even when the upper and lower chucks 10 and 11 are in the open state, the rotational power can be transmitted to the polishing plate 5 by the respective motors 14 and 15.

  Each pin 38.39 is inserted so as to be caught in the grooves of the notches 40 and 41. For this reason, it is possible to perform stable polishing even when the upper and lower chucks 10 and 11 are opened, because the tilting motion by the cans 6 and 8 is not disturbed while transmitting the rotational power.

  In the present embodiment, also in the second polishing step, the rotational motion can be stably transmitted to the lens 3 and the polishing dish 5, and the lens 3 with higher polishing surface accuracy can be obtained.

(A) is a figure which shows the 1st grinding | polishing process in 1st Embodiment, (b) is a figure which shows the 2nd grinding | polishing process. (A) is a figure which shows the 1st grinding | polishing process in 2nd Embodiment, (b) is a figure which shows the 2nd grinding | polishing process. (A) is a figure which shows the dimensional relationship of a grinding | polishing dish, (b) is a figure which shows the dimensional relationship of a lens. It is a figure which shows the 2nd grinding | polishing process in 3rd Embodiment. It is sectional drawing of the conventional grinder. (A) is a figure which shows the 1st grinding | polishing process in the conventional grinding | polishing apparatus, (b) is a figure which shows the 2nd grinding | polishing process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper shaft unit 2 Lower shaft unit 3 Lens 4 Holder 5 Polishing pan 6 Upper shaft body 7 Upper shaft cylinder 8 Lower shaft body 9 Lower shaft cylinder 10 Upper shaft chuck 11 Lower shaft chuck 12 Upper shaft spindle 13 Lower shaft spindle 14 Upper shaft Motor 15 Lower shaft motor 16 Control device M Polishing device P Upper shaft load Q Lower shaft load R Curvature radius α Polishing plate half angle β Lens half angle θ ₁ First relative angle θ ₂ Second relative angle D ₁ Polishing plate diameter D ₂ Lens diameter

Claims (4)

In a polishing method in which the rotation axis of a polishing dish is inclined with respect to the rotation axis of the work and the workpiece is brought into contact with and pressed against the polishing dish, and the work is polished by moving the workpiece and the polishing dish relative to each other.
The workpiece is held so as to be rotatable and tilted, the tiltable support of the polishing dish is fixed and the workpiece is brought into contact with the polishing dish, and polishing is performed by relative rotational movement and swinging movement of the workpiece and the polishing dish. A first polishing step for processing;
A second polishing step of holding the polishing dish so as to be capable of rotating and tilting, fixing the tiltable support of the work and subsequently performing a polishing process by a relative rotational movement and swinging movement of the work and the polishing dish; With
A polishing method characterized by the above. When shifting to the second polishing step, polishing is performed with a smaller inclination than the angle at which the polishing dish is inclined in the first polishing step.
The polishing method according to claim 1, wherein: When shifting to the second polishing step, the polishing plate is disposed with an inclination smaller than the angle at which the polishing plate is inclined in the first polishing step, and polishing is performed while transmitting rotational power to the polishing plate. Do,
The polishing method according to claim 1, wherein: A polishing apparatus in which a rotation axis of a polishing dish is inclined with respect to a rotation axis of the work, the work is brought into contact with the polishing dish and pressurized, and a relative motion is applied to the work and the polishing dish to polish the work. In
A first chuck means for holding the workpiece in a rotationally tiltable manner and fixing a tiltable support of the workpiece;
A second chuck means for holding the polishing dish so as to be capable of rotating and tilting and fixing the tilting support of the polishing dish;
The second chuck means fixes the tiltable support of the polishing dish in a state where the work is supported so as to be rotatable and tiltable.
The first chuck means fixes the tiltable support of the workpiece in a state where the polishing dish is rotatably supported.
A polishing apparatus characterized by that.