JP2024001562A - Polishing method and polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing method and a polishing device which can suppress the occurrence of a defective workpiece.

SOLUTION: A polishing method comprises the steps of: performing the first polishing processing; acquiring the height position in the center axis direction of a workpiece holding mechanism that holds a workpiece after the first polishing processing; calculating the height of a polishing surface of a grindstone on the basis of the height position of the workpiece holding mechanism and the previously-acquired thickness of the workpiece; calculating a height change amount of the polishing surface of the grindstone after the first polishing processing on the basis of the height of the polishing surface of the grindstone before and after the first polishing processing; acquiring a curvature radius of the polishing surface of the grindstone; calculating a change amount of an area of the polishing surface of the grindstone after the first polishing processing on the basis of the height change amount of the polishing surface of the grindstone and the curvature radius of the polishing surface of the grindstone; adjusting a polishing processing condition of the workpiece on the basis of the change amount of an area of the polishing surface of the grindstone; and performing the second polishing processing on the basis of the polishing processing condition after adjustment.

SELECTED DRAWING: Figure 4

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a polishing method and a polishing apparatus.

Patent Document 1 discloses a technique for determining polishing processing conditions such as processing pressure and processing rotation speed based on the contact area between a workpiece to be polished and a grindstone.

Patent No. 5453459

In polishing a workpiece, a rotated workpiece is rubbed against a whetstone that is oscillated and rotated so that the shape of the whetstone approaches the shape of the workpiece. Thereby, the shape of the workpiece is made into a desired spherical shape. In this polishing process, when multiple workpieces are processed with the same grindstone, the grindstone gradually wears out, and the shape of the workpieces processed later changes.

When the polishing surface of the grindstone is worn out by repeating the polishing process, the height (depth) of the polishing surface of the grindstone changes, and the area of the polishing surface also changes. When the area of the polishing surface of the grindstone changes in this way, the amount of polishing of the workpiece changes even if polishing is performed under the same polishing conditions as before. As a result, the processing quality of the workpiece may differ from expectations, which may lead to defects.

The present invention has been made in view of the above, and an object of the present invention is to provide a polishing method and a polishing apparatus that can suppress the occurrence of defective workpieces.

In order to solve the above-mentioned problems and achieve the purpose, a polishing method according to the present invention performs a first polishing process by bringing a rocking grindstone into contact with a workpiece rotated around a central axis. a step of acquiring the height position in the central axis direction of the workpiece holding mechanism that holds the workpiece after the first polishing process; and a step of acquiring the height position of the workpiece holding mechanism and the previously acquired height position of the workpiece holding mechanism. a step of calculating the height of the polishing surface of the grindstone based on the thickness; and a step of calculating the height of the polishing surface of the grindstone after the first polishing process based on the height of the polishing surface of the grindstone before and after the first polishing process. a step of calculating an amount of change in the height of the polishing surface of the whetstone, a step of obtaining a radius of curvature of the polishing surface of the whetstone, an amount of change in height of the polishing surface of the whetstone, a radius of curvature of the polishing surface of the whetstone. a step of calculating the amount of change in the area of the polishing surface of the grindstone after the first polishing process based on the amount of change in the area of the polishing surface of the grindstone, and adjusting the polishing conditions of the workpiece based on the amount of change in the area of the polishing surface of the grindstone. and a step of performing a second polishing process based on the adjusted polishing conditions.

In the above invention, the polishing method according to the present invention further includes the step of obtaining, as the thickness of the workpiece, the thickness of the workpiece after a polishing process performed before the first polishing process.

In the polishing method according to the present invention, in the above invention, the step of adjusting the polishing conditions includes processing the grindstone when the amount of change in the area of the polishing surface of the grindstone exceeds a predetermined threshold value. The area of the polishing surface is corrected to a predetermined area of the polishing surface.

In the polishing method according to the present invention, in the above invention, the step of adjusting the polishing conditions is performed when the amount of change in the area of the polishing surface of the grindstone exceeds a predetermined threshold value. The contact pressure of the grindstone or the swing angle of the grindstone is changed.

In the polishing method according to the present invention, in the above invention, the step of adjusting the polishing conditions further includes adjusting the polishing conditions based on the relationship between the radius of curvature of the workpiece and the area of the polishing surface of the grindstone. It is determined whether adjustment is necessary or not, and when it is determined that adjustment of the polishing conditions is necessary, the polishing conditions are adjusted.

In the above invention, the polishing method according to the present invention further includes the step of aligning the center of oscillation of the whetstone with the center of curvature of the polishing surface of the whetstone, based on the amount of change in height of the polishing surface of the whetstone. .

In the polishing method according to the present invention, in the above invention, the step of acquiring the height position is a step of measuring a total change in the thickness of the workpiece and the thickness of the grindstone that changes after the first polishing process. The total change in the thickness of the workpiece and the thickness of the grindstone is measured by a displacement sensor that is provided in the workpiece holding mechanism and measures displacement of the workpiece in the direction of the central axis.

In order to solve the above-mentioned problems and achieve the purpose, a polishing apparatus according to the present invention includes a work holding mechanism that holds a work to be polished, a grindstone for polishing the work, and a grindstone that holds the grindstone. , a grindstone holding mechanism for swinging, a height measuring mechanism for measuring the height position of the workpiece holding mechanism, a correction processing mechanism for correcting the area of the polishing surface of the grindstone, and a grinding process. a grinding wheel area calculation mechanism that calculates the amount of change in the area of the polishing surface of the grindstone based on the thickness of the workpiece and the height position of the work holding mechanism; and a correction necessity determination mechanism that determines whether or not correction of the grindstone by the correction processing mechanism is necessary.

In the polishing apparatus according to the present invention, in the above-mentioned invention, the correction necessity determining mechanism determines the need for the correction based on the amount of change in the area of the polishing surface of the grindstone and the radius of curvature before processing of the workpiece to be input into the polishing process. It is determined whether or not the correction processing mechanism needs to correct the grindstone.

In the polishing method and polishing apparatus according to the present invention, by adjusting the polishing conditions of the workpiece based on the amount of change in the area of the polishing surface of the grindstone, it is possible to process the workpiece with the expected quality. It is possible to suppress the generation of workpieces.

FIG. 1 is a diagram showing an example of the configuration of a polishing apparatus according to an embodiment of the present invention. FIG. 2 is a side view of the grindstone of the polishing apparatus according to the embodiment of the present invention, and is an explanatory diagram for explaining changes in the height and inner diameter of the grindstone. FIG. 3 is a diagram showing an example of a correction processing mechanism in a polishing apparatus according to an embodiment of the present invention. FIG. 4 is a flowchart showing the flow of the polishing method according to the embodiment of the present invention. FIG. 5 is a diagram showing an example of a chart for managing the processing quality of a workpiece in the polishing method according to the embodiment of the present invention.

Embodiments of a polishing method and a polishing apparatus according to the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the following embodiments, and the components in the following embodiments include those that can be easily replaced by those skilled in the art, or those that are substantially the same.

(polishing equipment)
A polishing apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. The polishing apparatus 1 is for polishing a work W. This polishing apparatus 1 is capable of polishing both a workpiece W having a convex surface and a workpiece W having a concave surface. In this embodiment, as shown in FIG. 1, a polishing apparatus 1 that polishes a workpiece W having a convex surface processed will be described.

The polishing device 1 includes a workpiece holding mechanism 11, a pressure cylinder 12, a workpiece rotation mechanism 13, a height measurement mechanism 14, a grindstone 15, a grindstone holding mechanism 16, a grindstone rotation mechanism 17, and a grindstone area calculation mechanism. 18, a correction necessity determining mechanism 19, a correction processing mechanism 20, and a shape evaluation mechanism 21. Note that although the grindstone area calculation mechanism 18, correction necessity determination mechanism 19, and shape evaluation mechanism 21 are illustrated as separate devices in FIG. 1, these mechanisms may be configured by one device.

The workpiece holding mechanism 11 is a mechanism for holding a workpiece W to be processed. The workpiece W may be, for example, a glass lens with a diameter of about 1 to 3 mm. The pressure cylinder 12 is a mechanism for pressing the work holding mechanism 11 in the direction of the central axis of the work W (hereinafter referred to as "work rotation axis") Aw with a predetermined pressure. The work rotation mechanism 13 is a mechanism for rotating the work holding mechanism 11 around the work rotation axis Aw.

The height measuring mechanism 14 is a mechanism for measuring the height position of the work holding mechanism 11. This height measuring mechanism 14 is provided in the work holding mechanism 11. Further, the height measuring mechanism 14 is configured by, for example, a displacement sensor (for example, a Z-axis scale, etc.) that measures the displacement of the workpiece W in the direction of the workpiece rotation axis Aw.

Here, when the workpiece W is polished, both the grindstone 15 and the workpiece W are worn out. As a result, the work holding mechanism 11 is pressed by the pressurizing cylinder 12 by the amount of wear on both parts, and the position of the work holding mechanism 11 moves downward. Therefore, as shown in FIG. 1, by installing the height measuring mechanism 14 in the workpiece holding mechanism 11, the total amount of wear of the workpiece W and the grindstone 15 can be detected.

The grindstone 15 is a tool for grinding the workpiece W. A flat portion 151 is provided on the edge of this grindstone 15 to prevent chipping. Further, the grindstone 15 has a polishing surface 152 for polishing the workpiece W. The grindstone holding mechanism 16 is a mechanism for holding the grindstone 15 and swinging it around a predetermined swing center. The grindstone rotation mechanism 17 is a mechanism for rotating the grindstone holding mechanism 16 around the central axis (hereinafter referred to as "grindstone rotation axis") At of the grindstone 15.

Furthermore, when the grindstone 15 is worn out due to polishing and the height of the grinding surface 152 of the grindstone 15 changes as shown in FIG. Based on this, the position of the grindstone 15 is corrected upward. Thereby, the center of swing of the grindstone 15 and the center of curvature of the polishing surface 152 of the grindstone 15 are made to coincide.

The grindstone area calculation mechanism 18 is a mechanism for calculating the amount of change in the area of the polishing surface 152 of the grindstone 15. The grindstone area calculation mechanism 18 calculates the area of the grindstone 15 based on the thickness of the workpiece W that has been polished, the radius of curvature of the workpiece W, and the height position of the workpiece holding mechanism 11 measured by the height measurement mechanism 14. The amount of change in the area of the polishing surface 152 is calculated. Specifically, the amount of change in height of the grinding wheel 15 is calculated using the thickness of the workpiece W after polishing this time and the previous one, and data on the height position of the workpiece holding mechanism 11 this time and the previous one. do. Further, assuming that the radius of curvature of the workpiece W and the radius of curvature of the polishing surface 152 substantially match, the area of the grindstone is calculated from the amount of change in the height of the grindstone and the radius of curvature of the polishing surface 152.

Note that for the "thickness of the workpiece W" and the "radius of curvature of the workpiece W", measured values measured by, for example, a thickness measuring device (not shown) and the shape evaluation mechanism 21 can be used. Further, the calculated grindstone area is a value obtained by evaluating and calculating the workpiece W as a result of processing. Therefore, in order to reflect the information on the calculated grindstone area in the next process, it is necessary to interrupt the polishing process until the calculation of the grindstone area is completed. However, since the change in the grinding wheel area due to processing per piece is not necessarily large, it is possible to perform continuous production by starting the next processing without waiting for the calculation of the grinding wheel area, which increases productivity. can be improved.

The correction necessity determining mechanism 19 is a mechanism for determining whether or not correction of the grindstone 15 is necessary. The correction necessity determining mechanism 19 determines whether correction of the grindstone 15 by the correction processing mechanism 20 is necessary based on the amount of change in the area of the polishing surface 152 of the grindstone 15 .

The correction processing mechanism 20 is a mechanism for correcting the area of the polishing surface 152 of the grindstone 15. The correction processing mechanism 20 corrects the area of the polishing surface 152 of the grindstone 15 by grinding the flat portion 151 of the grindstone 15, as shown in FIG.

The shape evaluation mechanism 21 is a mechanism that is also used to evaluate the shape of the workpiece W that is currently introduced into the polishing apparatus 1 before processing. The shape evaluation mechanism 21 evaluates the shape of the workpiece W based on, for example, a previously prepared chart for managing the processing quality of the workpiece W (see FIG. 5, which will be described later). Note that the "shape of the workpiece W" specifically refers to the radius of curvature of the workpiece W.

(polishing method)
A polishing method according to an embodiment of the present invention will be described with reference to FIGS. 4 and 5. In the polishing method according to the embodiment, as shown in FIG. 4, the first polishing process (step S1), the height position acquisition process (step S2), the thickness acquisition process (step S3), and the height A calculation step (Step S4), a height change amount calculation step (Step S5), a grindstone inner diameter calculation step (Step S6), an area change amount calculation step (Step S7), and a processing condition adjustment step (Step S8). , a second polishing process (step S9).

In addition, in the polishing method according to the embodiment, the first polishing process (step S1) is a process of polishing the first workpiece W, and the second polishing process (step S9) is a process of polishing the first workpiece W. , is a step of polishing a second workpiece W different from the first workpiece W.

Further, the first polishing process (step S1) is performed based on the polishing conditions determined in the process condition adjustment process (step S8) performed after the previous polishing process. Further, the processing condition adjustment step (step S8) is carried out to determine the polishing conditions for the second polishing step (step S9). Further, in the polishing method according to the embodiment, the height calculation step, the height change amount calculation step, the grindstone inner diameter calculation step, and the area change amount calculation step are mainly performed by the grindstone area calculation mechanism 18.

<First polishing process>
In the first polishing process, the grindstone 15 and the workpiece W are brought into contact with each other to perform polishing (step S1). In the first polishing process, the grindstone 15 is rotated and swung around the grindstone rotation axis At by the grindstone holding mechanism 16. Further, the work holding mechanism 11 rotates the work W around the work rotation axis Aw. The workpiece W is then polished by rubbing the rotated and oscillated grindstone 15 against the rotated workpiece W.

<Height position acquisition process>
In the height position acquisition process, after the first polishing process, the height position of the workpiece holding mechanism 11 that holds the workpiece W in the direction of the workpiece rotation axis Aw is acquired (step S2). In the height position acquisition step, the total change in the thickness of the workpiece W and the grindstone 15 that changes after the first polishing step is measured by the height measurement mechanism 14 made of, for example, a displacement sensor.

That is, the height measurement mechanism 14 measures the total value of the thickness of the workpiece W and the thickness of the grindstone 15 (hereinafter referred to as "total thickness value") by measuring the height position of the workpiece holding mechanism 11. In addition, the height measuring mechanism 14 measures the total thickness every time the polishing device 1 polishes the workpiece W, and thereby calculates the total thickness value in the current polishing process and the total thickness value in the previous polishing process. The difference in thickness, that is, the amount of change in the total thickness value, is measured.

<Thickness acquisition process>
In the thickness acquisition step, the thickness (thickness) of the workpiece W that has been polished is acquired (step S3). In the thickness acquisition step, the thickness of the workpiece W after polishing is measured by a thickness measuring mechanism (not shown). At this time, the radius of curvature of the work W may be measured using the shape evaluation mechanism 21 as well as the thickness of the work W.

Here, in the thickness acquisition step, the workpiece W being polished may be temporarily removed from the polishing apparatus 1 and the thickness of the workpiece W may be measured. It is more preferable to obtain the thickness of the workpiece W after the process. This is because, when the height of the workpiece holding mechanism 11 is being acquired in the height position acquisition process, the thickness of the workpiece W being polished cannot be acquired. Therefore, it is necessary to remove the workpiece W from the workpiece holding mechanism 11 and measure it, resulting in the interruption of the polishing process. Moreover, if the workpiece W is attached and removed during polishing, processing defects are likely to occur. On the other hand, in the thickness acquisition step, by acquiring the thickness of the workpiece W that has already been polished, it is possible to acquire the information necessary for adjusting the polishing conditions of the workpiece W without interrupting the polishing process. .

<Height calculation process>
In the height calculation step, the height of the polishing surface 152 of the grindstone 15 is calculated based on the height position of the workpiece holding mechanism 11 obtained in the height position acquisition step and the thickness of the workpiece W obtained in the thickness acquisition step. (Step S4). In the height calculation step, the height of the polishing surface 152 of the grindstone 15 is calculated by subtracting the thickness of the workpiece W from the height position of the workpiece holding mechanism 11, that is, the total thickness of the workpiece W and the grindstone 15.

<Height change amount calculation process>
In the height change calculation step, the amount of height change of the polishing surface 152 of the grindstone 15 after the first polishing process is calculated based on the height of the polishing surface 152 of the grindstone 15 before and after the first polishing process. is calculated (step S5). In the height change calculation process, the height of the polishing surface 152 of the grinding wheel 15 after the first polishing process (current polishing process) is calculated from the height of the polishing process performed before the first polishing process (previous polishing process). By subtracting the height of the polishing surface 152 of the grindstone 15 after the polishing process), the amount of change in height of the polishing surface 152 of the grindstone 15 is calculated. Note that although the above method calculates the amount of change in height from the absolute value of the height of the grindstone, the amount of change in height may also be calculated from the relative amount of change. Specifically, from the difference between the height of the workpiece holding mechanism 11 during the current polishing and the height of the workpiece holding mechanism 11 during the previous polishing, the thickness of the workpiece W after the current polishing and the workpiece W after the previous polishing are determined. By subtracting the difference from the thickness of , the height change amount of the polishing surface 152 of the grindstone 15 is calculated.

<Whetstone inner diameter calculation process>
In the grindstone inner diameter calculation step, the inner diameter of the polishing surface 152 of the grindstone 15 is calculated (step S6). In the grindstone inner diameter calculation process, the inner diameter of the polishing surface 152 of the grindstone 15 is calculated based on the radius of curvature of the workpiece W acquired together with the thickness in the thickness acquisition process. In addition, in the process of calculating the internal diameter of the grindstone, the measured radius of curvature of the workpiece W may be used as the radius of curvature of the polishing surface 152 of the grindstone 15, but it is also possible to use a measurement value obtained by directly measuring the radius of curvature of the polishing surface 152 of the grindstone 15. It's okay.

<Area change calculation process>
In the area change amount calculation step, a first The amount of change in the area of the polishing surface 152 of the grindstone 15 after the first polishing process is calculated (step S7). In the present embodiment, the area of the polishing surface 152 of the grindstone 15 is calculated from the calculated inner diameter of the polishing surface 152 of the grindstone 15 and the amount of height change of the polishing surface 152. It is also possible to calculate the area of the grindstone 15 using the radius of curvature of the polishing surface 152 instead of the inner diameter.

<Processing condition adjustment process>
In the processing condition adjustment step, the polishing conditions for the workpiece W in the second polishing step are adjusted based on the amount of change in the area of the polishing surface 152 of the grindstone 15 calculated in the area change calculation step (Step S8). .

In the processing condition adjustment step, for example, as shown in FIG. 3, by processing the flat portion 151 of the grinding wheel 15 using the correction processing mechanism 20, the area of the grinding surface 152 of the grinding wheel 15 is adjusted to a predetermined (desired) area of the grinding surface 152. Correct to area. Note that the processing of the flat portion 151 of the grindstone 15 in the processing condition adjustment step is performed, for example, when the amount of change in the area of the polishing surface 152 of the grindstone 15 exceeds a predetermined threshold value. In this way, in order to maintain the processing quality of the workpiece W, the amount of polishing of the workpiece W can be adjusted by correcting the area of the polishing surface 152 of the grindstone 15. In addition, in this embodiment, since the inner diameter of the polishing surface 152 of the grinding wheel 15 is calculated, the edge of the grinding wheel 15 due to the flat part 151 disappearing and the edge part of the inner diameter of the grinding wheel 15 becoming an acute angle. It is also possible to utilize the correction processing mechanism 20 to prevent chipping.

Further, in the processing condition adjustment step, the polishing processing conditions may be adjusted by, for example, changing the contact pressure between the grindstone 15 and the workpiece W or the swing angle of the grindstone 15. In this case, when the amount of change in the area of the polishing surface 152 of the grindstone 15 exceeds a predetermined threshold value, the contact pressure between the grindstone 15 and the work W or the swing angle of the grindstone 15 is changed. In this manner, in order to maintain the processing quality of the workpiece W, the amount of polishing of the workpiece W can be adjusted by changing the contact pressure between the grindstone 15 and the workpiece W and the swing angle of the grindstone 15.

In addition, in the processing condition adjustment step, it is further determined whether the polishing conditions need to be adjusted based on the relationship between the radius of curvature of the work W and the area of the polishing surface 152 of the grindstone 15, and the polishing conditions are adjusted. If it is determined that polishing is necessary, the polishing conditions may be adjusted. In this case, the shape evaluation mechanism 21 determines whether or not the polishing conditions need to be adjusted, based on a chart prepared in advance as shown in FIG. 5, for example.

That is, in the processing condition adjustment step, the radius of curvature of the workpiece W input into the polishing device 1 or the area of the polishing surface 152 of the grindstone 15 is within the control range defined in the chart (denoted as "Area 1" in the figure). If it is within the range, it is determined that there is no need to adjust the polishing conditions. On the other hand, in the processing condition adjustment step, if the radius of curvature of the workpiece W input into the polishing device 1 or the area of the polishing surface 152 of the grindstone 15 is outside the control range defined in the chart table, the polishing conditions are adjusted. is determined to be necessary. A more specific method of using the chart will be described below with reference to FIG.

FIG. 5 shows a chart when processing a work W having a diameter of Φ1 mm. In the figure, the vertical axis represents the radius of curvature of the workpiece W to be introduced into the polishing apparatus 1, and the horizontal axis represents the area of the grindstone 15. Further, the chart shown in the figure is created in advance using a general statistical method (for example, multiple regression analysis, etc.) before implementing the polishing method according to the embodiment. When using multiple regression analysis, the quality of the work W after polishing (number of NR (Newton rings)) is used as an objective variable, and the quality of the work W to be input (number of NR) and the area of the grindstone 15 are used as explanatory variables.

For example, if the radius of curvature of the workpiece W input into the polishing device 1 and the area of the grindstone 15 are within the range of Area 1 in FIG. ). In this case, the radius of curvature of the workpiece W to be fed into the polishing device 1 and the area of the grindstone 15 are set within an arbitrary range within this Area 1.

Specifically, in FIG. 5, the radius of curvature R1 of the workpiece W was set to "1 NR", and the radius of curvature R2 was set to "2 NR". Further, the area S1 of the grindstone 15 was set to "0.70 mm ² ", and the area S2 was set to "0.78 mm ² ". In this case, as shown by A in the figure, by maintaining the area of the grindstone 15 between S1 and S2, a workpiece W having a radius of curvature R1 to R2 is polished and becomes a non-defective product.

It is also possible to use the chart shown in FIG. 5 as follows. For example, if the radius of curvature of the workpiece W to be fed into the polishing device 1 is R4 (for example, NR4), which is outside R1 to R2, if the area of the grindstone 15 is maintained at S1 to S2, the polished workpiece W becomes defective. Therefore, as shown by B in FIG. 5, by correcting the area of the grindstone 15 to S3 in the processing condition adjustment step, it is possible to obtain a non-defective product. Moreover, contrary to the above, if the area of the grindstone 15 becomes S3 as a result of the previous polishing process, a good product can be obtained by putting the workpiece W with the radius of curvature R4 into the polishing device 1 accordingly. becomes possible.

Here, the size of the area of the polishing surface 152 of the grinding wheel 15 is related to the ability to correct the radius of curvature of the workpiece W input into the polishing device 1. Therefore, the radius of curvature of the workpiece W input into the polishing apparatus 1 is If the radius of curvature is close to , it is possible to obtain good polishing quality even if the area of the polishing surface 152 of the grindstone 15 is somewhat small.

Therefore, in the machining condition adjustment step, as shown in FIG. 5, it is preferable to determine whether correction machining of the grindstone 15 is necessary depending on the quality (radius of curvature) of the workpiece W input into the polishing apparatus 1. That is, by preparing a chart as shown in the figure in advance, it is possible to estimate the quality of the finished workpiece W after polishing from the radius of curvature of the workpiece W to be introduced and the area of the grindstone 15. Utilizing this mechanism, the quality of the workpiece W after polishing can be estimated in advance, and if it is estimated to be defective, the quality of the workpiece W can be stabilized in a feedforward manner by performing correction processing on the grindstone 15. . Further, even if workpieces W having different shapes are inputted into the polishing apparatus 1, workpieces W having a desired shape can be continuously and automatically processed, and productivity can be increased.

<Second polishing process>
In the second polishing process, the workpiece W is polished based on the polishing conditions adjusted in the process condition adjustment process (step S9). In the second polishing process, similarly to the first polishing process, the workpiece W is polished by rubbing the rotated and oscillated grindstone 15 against the rotated workpiece W.

<Sphere center matching process>
Here, in the polishing method according to the embodiment of the present invention, the spherical center matching step may be performed, for example, after the area change amount calculation step and before the second polishing step. In the ball center matching step, the center of swing of the grinding wheel 15 and the center of curvature of the grinding surface 152 of the grinding wheel 15 are matched based on the height change amount of the grinding surface 152 of the grinding wheel 15 calculated in the height change calculation step. let In this case, for example, by moving the position of the whetstone 15 upward (in the case of FIG. 1) by the amount by which the polishing surface 152 of the whetstone 15 is worn (height change amount) by the whetstone holding mechanism 16, the position of the whetstone 15 is The center of oscillation is made to coincide with the center of curvature of the polishing surface 152 of the grindstone 15. Note that the spherical center matching process is performed each time the workpiece W is polished (for each workpiece W).

When the height of the polishing surface 152 of the grindstone 15 changes, not only the area of the polishing surface 152 but also the center of curvature of the polishing surface 152 changes. Therefore, as described above, by correcting the position of the grindstone 15 in accordance with the wear of the polishing surface 152 of the grindstone 15, the workpiece W can be moved with higher accuracy without changing the swing center and swing radius of the grindstone 15. Can be polished.

In the polishing method and polishing apparatus according to the present embodiment described above, the height of the polishing surface 152 of the grindstone 15 is calculated based on the height position of the workpiece holding mechanism 11 and the thickness of the workpiece W. Furthermore, the amount of change in the area of the polishing surface 152 of the grindstone 15 is calculated based on the height of the polishing surface 152 of the grindstone 15 and the radius of curvature of the polishing surface 152 of the grindstone 15 . Then, by adjusting the polishing conditions of the workpiece W based on the amount of change in the area of the polishing surface 152 of the grindstone 15, the workpiece W is processed with the expected quality. Thereby, the occurrence of defective workpieces W can be suppressed, and the processing quality of the workpieces W can be maintained.

Furthermore, in the polishing method and polishing apparatus according to the present embodiment, the shape of the grindstone 15 (area of the polishing surface 152) that changes over time is estimated from the height position of the workpiece holding mechanism 11 and the thickness of the workpiece W. However, if necessary, before the next polishing of the work W, the grindstone 15 is corrected or the contact pressure with the work W is changed.

Thereby, changes in the area of the polishing surface 152 of the grindstone 15 can be grasped without stopping the polishing apparatus 1 and measuring the height and area of the polishing surface 152 of the grindstone 15. As a result, the workpiece W can be continuously machined while the appropriate shape of the grindstone 15 is always maintained. Further, since the correction processing of the grindstone 15 can be automatically performed, it is possible to suppress the occurrence of defective workpieces W. In other words, each time a defective workpiece W occurs, the polishing device 1 can be stopped and good products can be obtained continuously without the operator having to adjust the conditions or perform correction processing. It can be realized.

For example, in the past, the height of the grindstone was directly measured by stopping the polishing apparatus periodically and pressing a sensor against the grindstone. In this case, it was necessary to remove the grindstone from the polishing device, and the height could only be determined when the grindstone was removed. On the other hand, in the polishing method and polishing apparatus according to the present embodiment, the polishing surface of the grindstone 15 is determined only by the information on the height position of the workpiece holding mechanism 11, the thickness of the workpiece W, and the information on the radius of curvature of the workpiece W or the grindstone 15. The area of 152 can be found. Furthermore, since the area of the polishing surface 152 of the grindstone 15 is determined every time a new workpiece W is processed, the amount of change in the area of the polishing surface 152 of the grindstone 15 can be grasped in real time.

Above, the polishing method and polishing apparatus according to the present invention have been specifically explained using the mode for carrying out the invention, but the gist of the present invention is not limited to these descriptions, and the scope of the claims must be interpreted broadly based on Furthermore, it goes without saying that various changes and modifications based on these descriptions are also included within the spirit of the present invention.

For example, as the workpiece W to be polished, in addition to glass lenses, the present invention can be widely applied to objects to be essentially processed into a lens shape or a spherical shape. In addition, the workpiece W is mainly applicable to glass materials, but any material that can be polished is not subject to restrictions, such as glass, ceramics such as sapphire and alumina, metals, resins, and stones. do not have.

Further, the device configuration of the polishing device 1 may be such that each component is configured integrally, or each component may be divided and installed as long as it can exhibit the same effect as the present invention. It may be something that has been done.

In addition, in the machining condition adjustment process, the logic for determining whether correction machining of the grindstone 15 is necessary is based on the curvature accuracy of the workpiece W and the machining conditions for each specific shape of the workpiece W, as shown in FIG. Although it is desirable to find it statistically from the parameters, generalized criteria may be set so that it can be applied to various shapes of workpieces W.

Further, although there is a method of pre-inspecting all the workpieces W to be input into the polishing apparatus 1 for the curvature accuracy of the workpieces W, it is also useful to improve efficiency by, for example, utilizing test results from lot inspections.

In addition, depending on the area of the polishing surface 152 of the grinding wheel 15, a workpiece W that can yield a good product is inputted, and when the corresponding workpiece W is no longer available, correction processing of the grinding wheel 15 is performed, etc. Various management methods are carried out according to the circumstances of production. It goes without saying that improvements in methods can be made by utilizing the present invention.

In addition, instead of the correction processing mechanism 20 that changes the area of the polishing surface 152 of the grindstone 15 in accordance with a change in the area of the polishing surface 152 of the grindstone 15, the grindstone 15 can be adjusted according to the increased area of the polishing surface 152. A means for changing the pressure so as to keep the contact pressure with the workpiece W constant, and a means for changing the relative speed between the grindstone 15 and the workpiece W, such as the swing angle and swing speed of the grindstone 15, are adopted. You may.

1 Polishing device 11 Work holding mechanism 12 Pressure cylinder 13 Work rotating mechanism 14 Height measuring mechanism 15 Grinding wheel 151 Flat part 152 Polishing surface 16 Grinding wheel holding mechanism 17 Grinding wheel rotation mechanism 18 Grinding wheel area calculation mechanism 19 Correction necessity determination mechanism 20 Correction machining Mechanism 21 Shape evaluation mechanism At Grinding wheel rotation axis Aw Workpiece rotation axis W Workpiece

Claims (9)

A step of performing a first polishing process by bringing the oscillating grindstone into contact with the workpiece rotated around a central axis;
After the first polishing process, acquiring the height position of the workpiece holding mechanism that holds the workpiece in the central axis direction;
Calculating the height of the polishing surface of the grindstone based on the height position of the workpiece holding mechanism and the thickness of the workpiece obtained in advance;
calculating an amount of change in the height of the polishing surface of the grindstone after the first polishing process based on the height of the polishing surface of the grindstone before and after the first polishing process;
obtaining the radius of curvature of the polishing surface of the grindstone;
Calculating the amount of change in the area of the polished surface of the grindstone after the first polishing process based on the amount of change in height of the polished surface of the grindstone and the radius of curvature of the polished surface of the grindstone;
adjusting the polishing conditions of the workpiece based on the amount of change in the area of the polishing surface of the grindstone;
a step of performing a second polishing process based on the adjusted polishing conditions;
Polishing methods including. The polishing method according to claim 1, further comprising the step of obtaining, as the thickness of the workpiece, the thickness of the workpiece after a polishing process performed before the first polishing process. In the step of adjusting the polishing conditions, when the amount of change in the area of the polishing surface of the grindstone exceeds a predetermined threshold value, the area of the polishing surface is adjusted to a predetermined polishing surface by processing the grindstone. 3. The polishing method according to claim 1, wherein the polishing method is corrected to an area of . In the step of adjusting the polishing conditions, when the amount of change in the area of the polishing surface of the grindstone exceeds a predetermined threshold, the contact pressure between the grindstone and the workpiece, or the swing angle of the grindstone is adjusted. The polishing method according to claim 1 or 2, wherein the polishing method is changed. The step of adjusting the polishing conditions further includes determining whether adjustment of the polishing conditions is necessary based on the relationship between the radius of curvature of the workpiece and the area of the polishing surface of the grindstone, and adjusting the polishing conditions. The polishing method according to claim 3, wherein the polishing conditions are adjusted when it is determined that adjustment of the conditions is necessary. 6. The polishing method according to claim 5, further comprising the step of aligning the center of oscillation of the whetstone with the center of curvature of the polishing surface of the whetstone based on the amount of change in height of the polishing surface of the whetstone. The step of acquiring the height position is a step of measuring a total change in the thickness of the workpiece and the thickness of the grindstone that changes after the first polishing process,
The total change in the thickness of the workpiece and the thickness of the grindstone is measured by a displacement sensor that is provided in the workpiece holding mechanism and measures displacement of the workpiece in the central axis direction.
The polishing method according to claim 1. a work holding mechanism that holds a work to be polished;
a grindstone for polishing the work;
a grindstone holding mechanism for holding and swinging the grindstone;
a height measuring mechanism that measures the height position of the work holding mechanism;
a correction processing mechanism for correcting the area of the polishing surface of the grindstone;
a grindstone area calculation mechanism that calculates an amount of change in the area of the polishing surface of the grindstone based on the thickness of the workpiece that has been polished and the height position of the workpiece holding mechanism;
a correction necessity determination mechanism that determines whether correction of the grindstone by the correction processing mechanism is necessary based on the amount of change in the area of the polishing surface of the grindstone;
A polishing device equipped with. The correction necessity determining mechanism determines whether or not the correction processing mechanism needs to correct the grindstone based on the amount of change in the area of the polishing surface of the grindstone and the radius of curvature of the workpiece to be subjected to polishing before processing. judge,
The polishing device according to claim 8.

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