JP2021124381A - Glass plate shape measuring method and glass article manufacturing method - Google Patents

Abstract

To provide a glass plate shape measuring method, with which it is possible to confirm the size of warp of a glass plate without reversing the glass plate.SOLUTION: The shape measuring method comprises: a measurement step S21 in which a glass plate is placed with a first principal surface facing upward on a reference plane and height positions of first principal surface of the glass plate are measured at multiple points; a first determination step S22 in which a direction of warp per block is determined for each block into which the glass plate is divided, on the basis of a measurement result of the measurement step; and second determination steps S23-S25 in which a warp value per block is obtained in accordance with the direction of warp of the glass plate per block having been obtained by the first determination step. When it is determined in the second determination steps S24-S25 that an object block has a warp in such a direction that the top side protrudes, a correction value, with the height position of first principal surface of the glass plate in said block corrected, is obtained and this correction value is defined to be an estimated warp value W2 of said block.SELECTED DRAWING: Figure 6

Description

The present invention relates to a method for measuring the shape of a glass plate such as a crystallized glass plate and a method for manufacturing a glass article.

The crystallized glass plate is produced, for example, by heating and crystallizing a crystalline glass plate formed by roll molding. Then, both sides of the crystallized glass plate whose warpage is equal to or less than the specified value are polished in order to increase the glossiness. Therefore, the shape of the crystallized glass is measured in advance. As a method of measuring the shape of the glass plate, for example, as disclosed in Patent Document 1, the surface shape of the glass plate placed on the reference surface is measured by using a sensor such as a laser displacement meter. It has been known.

Japanese Unexamined Patent Publication No. 2013-130417

As shown in FIG. 7, the warp of the glass plate G1 is classified into a warp Wa in the direction of being concave on the upper side and a warp Wb in the direction of being convex on the upper side. When the glass plate G1 is inverted, the warp Wb in the upward convex direction becomes a warp Wa in the upward concave direction.

When measuring the warp of the glass plate G1, it is necessary to consider that the glass plate G1 bends in a direction in which the warp becomes smaller due to its own weight, depending on the direction of the warp. For example, the amount of lift of the glass plate G1 from the reference surface S when the glass plate G1 is placed on the reference surface S is defined as the warp value W. In this case, the warp value W when the glass plate G1 is placed on the reference surface S so that the warped portion is convex upward is placed by reversing the glass plate so that the warped portion is concave upward. It becomes smaller than the warp value W of the same part when placed.

Therefore, in the shape measurement of the crystallized glass plate performed before the polishing treatment, the shape is measured with the crystallized glass plate placed on the platen with the first main surface facing upward, and then the crystallized glass plate is measured. Is inverted, and the shape is measured again with the second main surface facing upward, thereby eliminating the influence of its own weight.

In order to measure the shape of the crystallized glass plate on the production line, in addition to the shape measuring device, an inversion device for inverting the crystallized glass plate must be installed. Therefore, there is a problem that a large installation space and a high installation cost are required.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for measuring the shape of a glass plate and a method for manufacturing a glass article, which can confirm the amount of warpage of the glass plate without inverting the glass plate. To provide.

In the method for measuring the shape of a glass plate that solves the above problems, the glass plate is placed on a reference surface with the first main surface of the glass plate having the first main surface and the second main surface facing up. Based on the measurement step of placing and measuring the height position of the first main surface of the glass plate at a plurality of places and the measurement result of the measurement step, each block of the glass plate is divided into blocks. A first determination step of determining the direction of warpage and a second determination step of obtaining a warp value for each block according to the direction of warpage of the glass plate of the block obtained by the first determination step. In the first determination step, when it is determined in the first determination step that the target block has a warp in a direction that is convex upward, the first main surface of the glass plate in the block is provided. The warp value of the block is obtained based on the correction value obtained by correcting the height position of the block.

Most of the warping of a glass plate such as a crystallized glass plate occurs during post-treatment such as crystallization. The present inventor describes the warpage of the glass plate between the shape measured in the direction of being convex upward and the shape measured in the direction of reversing the glass plate and being concave upward. We found that there was a positive correlation.

In view of this knowledge, in the above shape measurement method, the warp is obtained for each block in which the measurement range is divided from the measurement result of the shape of the upper surface of the glass plate placed on the reference surface with the first main surface facing upward. The direction of is judged. Then, for the block determined to have a warp in the upward convex direction, a correction value obtained by correcting the height position of the first main surface of the glass plate based on the above correlation is obtained.

The correction value is a value close to the distance between the reference surface and the lower surface of the glass plate when the glass plate is inverted and the warp of the target block is measured as the warp in the direction of being concave upward. Therefore, the correction value can be regarded as an estimated value (estimated warp value) of the warp value excluding the influence of its own weight in the warp in the direction of being convex upward. Therefore, the magnitude of the warp can be confirmed without inverting the glass plate even for the warp in the direction of being convex upward.

In the method for measuring the shape of the glass plate, when the second determination step determines in the first determination step that the target block has a warp in the direction of being concave upward, the glass in the block. It is preferable to obtain the warp value of the block from the positional relationship between the first main surface of the plate and the reference surface.

In the method for measuring the shape of the glass plate, it is preferable that the measuring step measures the height position of the first main surface of the glass plate at many points on the edge side of the glass plate rather than the center side.

A method for producing a glass article that solves the above problems is a crystallization step of crystallizing a crystalline glass plate formed by roll molding to obtain a crystallized glass plate, and the crystallization using the method for measuring the shape of the glass plate. It is provided with a shape measuring step for measuring the amount of warpage of the glass-ceramic plate.

According to the present invention, the amount of warpage of the glass plate can be confirmed without inverting the glass plate.

Flowchart of manufacturing method of glass article. Top view of the shape measuring device. FIG. 2 is a sectional view taken along line 3-3 of FIG. FIG. 2 is a sectional view taken along line 4-4 of FIG. The explanatory view of the measurement range and the measurement point on the 1st main surface of a crystallized glass plate. Flowchart of shape measurement process. A perspective view of a crystallized glass plate having a warp.

Hereinafter, an embodiment of the present invention will be described.
As shown in FIG. 1, the method for producing a glass article includes a crystallization step S11 for obtaining a crystallized glass plate by crystallizing a crystalline glass plate, and a shape measuring step S12 for measuring the warp of the crystallized glass plate. A sorting step S13 for sorting the crystallized glass plate is provided.

(Crystallization process)
The crystallization step S11 is a firing step of arranging a crystalline glass plate in a firing furnace and firing the crystalline glass plate based on the ambient temperature in the firing furnace to obtain a crystallized glass plate.

As the crystalline glass plate, a glass plate formed by roll molding can be used. Examples of the crystalline glass include SiO ₂ : 50 to 75% by mass, Al ₂ O ₃ : 1 to 15% by mass, CaO: 6 to 18% by mass, Li ₂ O: 0.1 to 5% by mass, B ₂ O ₃ : 0 to 1.5% by mass, ZnO: 2.5 to 12% by mass, BaO: 0 to 12% by mass, Na ₂ O + K ₂ O: 0.1 to 15% by mass, As ₂ O ₃ + Sb ₂ O _3: 1 wt% or less, SrO + MgO: 2 wt% or _{less, Fe 2 O 3 + NiO +} CoO + MnO 2 + CuO: 0~12 _wt%, TiO _{2 +} ZrO _2: can be used with the following composition 1.5 wt%.

In the crystallization step, a plurality of crystalline glass plates stacked on the heat treatment setter are fired using a known heating device such as a roller harskiln. By this firing, the crystalline glass plate becomes a crystallized glass plate. The obtained crystallized glass plate is subjected to a cooling treatment, then separated into pieces and transported to the next process.

The crystallized glass plate has a flat plate shape having a first main surface and a second main surface. The planar shape of the crystallized glass plate is, for example, a rectangular shape. The thickness of the rectangular crystallized glass plate is, for example, 1 to 10 mm, the vertical dimension is, for example, 100 to 3000 mm, and the horizontal dimension is, for example, 100 to 2000 mm.

(Shape measurement process)
The shape measuring step S12 is a step of measuring the amount of warpage of the crystallized glass plate obtained in the crystallization step S11. The main factor of the warp that occurs in the crystallized glass plate is that the thermal history such as the cooling rate at the time of molding the crystalline glass plate is different. Warpage is likely to occur during firing in the crystallization step S11.

For example, during molding of a crystalline glass plate, when the molded crystalline glass plate is cooled from a high temperature state immediately after molding, the temperature of the edge side portion of the crystalline glass plate is higher than that of the central portion. Tends to decrease. In this case, the thermal history is different between the edge side portion and the center side portion of the crystalline glass plate. Such a difference in the thermal history for each part causes a difference in the timing of the formation of crystal nuclei and the growth of crystal nuclei when the crystalline glass is crystallized. As a result, warpage is likely to occur in parts having partially different thermal histories when molding the crystalline glass plate.

In particular, when a crystalline glass plate is molded by roll molding, the portions on both ends in the width direction orthogonal to the molding direction tend to cool when cooled from the high temperature state immediately after molding. It is easy to be different. Therefore, the warp generated in the crystallized glass plate obtained from the crystalline glass plate formed by roll molding is concentrated on the portions on both ends in the width direction orthogonal to the forming direction at the time of molding.

In the shape measuring step S12, the warp of the crystallized glass plate generated during firing in the crystallization step S11 is measured. Next, the shape measuring device 10 used in the shape measuring step will be described.
As shown in FIGS. 2 and 3, the shape measuring device 10 includes a surface plate 11 on which the crystallized glass plate G is placed in a flat position. The crystallized glass plate G in FIG. 2 shows only the outline.

The upper surface of the surface plate 11 is a horizontal reference surface 11a. A horizontal groove 12 extending in the X direction is provided on the reference surface 11a of the surface plate 11, and a transport device 13 such as a belt conveyor for transporting the crystallized glass plate G is installed in the horizontal groove 12. The transport device 13 is arranged so as to be located below the reference surface 11a of the surface plate 11, and moves above the reference surface 11a of the surface plate 11 when transporting the crystallized glass plate G. Then, the crystallized glass plate G can be conveyed.

The transport device 13 adjusts the position of the crystallized glass plate G in the X direction by moving the crystallized glass plate G placed on the reference surface 11a of the surface plate 11 in the X direction so as to be positioned at a predetermined measurement position. do. Further, the transport device 13 transports the crystallized glass plate G after measurement to the next process.

As shown in FIGS. 2 and 4, the surface plate 11 is provided with a plate thickness measuring unit 14 for measuring the plate thickness of the crystallized glass plate G. The plate thickness measuring unit 14 is a groove extending in the Y direction provided on the reference surface 11a of the surface plate 11, and is provided at two locations at intervals in the X direction.

As shown in FIGS. 2 and 3, centering for adjusting the position of the crystallized glass plate G placed on the reference surface 11a of the surface plate 11 is performed at both ends in the Y direction on the reference surface 11a of the surface plate 11. A mechanism 15 is provided. The centering mechanism 15 moves the crystallized glass plate G in the Y direction so as to position the crystallized glass plate G at a predetermined measurement position by moving forward and backward in the Y direction, and adjusts the position of the crystallized glass plate G in the Y direction.

As shown in FIG. 2, the shape measuring device 10 includes a shape measuring unit 20 for measuring the shape of the crystallized glass plate G placed on the reference surface 11a of the surface plate 11. The shape measuring unit 20 includes displacement sensors 21a to 21g for detecting various height positions of the crystallized glass plate G, a moving device 22 for supporting the displacement sensors 21a to 21g and moving the displacement sensors 21a to 21g, and displacement. It includes sensors 21a to 21g and a control unit 23 that controls the moving device 22. In the present embodiment, the height position of the reference surface 11a of the surface plate 11 is set to 0, and the displacement sensors 21a to 21g measure the height position with reference to the reference surface 11a of the surface plate 11.

The displacement sensors 21a to 21g are laser displacement meters arranged above the reference surface 11a of the platen 11, and irradiate the laser beam downward toward the crystallized glass plate G placed on the reference surface 11a. , Receives the laser light reflected from the crystallized glass plate G. The displacement sensors 21a to 21g transmit a detection signal based on the received laser beam to the control unit 23.

As shown in FIGS. 2 and 3, the moving device 22 includes a support base 24 that supports the displacement sensors 21a to 21g, and a drive unit 25 that moves the support base 24 forward and backward in the X direction. The support base 24 has a gate shape straddling the surface plate 11, and is located above the surface plate 11 with a pair of legs 24a located on both sides of the surface plate 11 in the Y direction and extending in the vertical direction. It is provided with a support portion 24b for connecting the upper ends of the pair of leg portions 24a.

Seven displacement sensors 21a to 21g are supported on the support portion 24b so as to be arranged in the Y direction. In the support portion 24b, three displacement sensors 21a to 21g are arranged at positions corresponding to above the portions on both ends in the Y direction of the crystallized glass plate G, and the center of the crystallized glass plate G in the Y direction. One is arranged at a position corresponding to the upper part of the portion.

The control unit 23 controls the operations of the displacement sensors 21a to 21g and the moving device 22, so that the height positions of a plurality of preset measurement points on the crystallized glass plate G arranged at the measurement positions, that is, fixed. The positional relationship between the reference surface 11a of the plate 11 and the crystallized glass plate G is measured. Specifically, the control unit 23 controls the drive unit 25 to move the support base 24 in the X direction, and positions the displacement sensors 21a to 21g supported by the support base 24 on each measurement point. Then, when the displacement sensors 21a to 21g are located above each measurement point, the displacement sensors 21a to 21g are controlled to measure the height position of the upper surface Ga or the lower surface Gb of the crystallized glass plate G. In the following, the upper surface Ga will be referred to as the first main surface Ga, and the lower surface Gb will be referred to as the second main surface Gb. Further, since the positional relationship between the displacement sensors 21a to 21g and the surface plate 11 can be obtained in advance at the time of device design, obtaining the height position of the measurement point on the crystallized glass plate G is the surface plate 11 It can be regarded as measuring the positional relationship between the reference surface 11a and the crystallized glass plate G.

FIG. 5 is a schematic view showing the positions of the measurement points on the first main surface Ga of the crystallized glass plate G arranged at the measurement positions, and each measurement point is given a different number. In the present embodiment, the measurement ranges A1 and A2 are partially set at the center and both ends of the first main surface Ga of the crystallized glass plate G in the Y direction, respectively. The measurement range A1 located on both ends of the first main surface Ga of the crystallized glass plate G in the Y direction is, for example, a range of 10 to 400 mm from the plate edge Gc (plate edge in the Y direction) of the crystallized glass plate G. Set in. The measurement range A2 on the center side in the Y direction of the first main surface Ga of the crystallized glass plate G is, for example, a range of 10 to 100 mm centered on the center line P that equally divides the crystallized glass plate G in the Y direction. Set in.

More measurement points are provided in the measurement range A1 located on both ends than in the measurement range A2 located in the center of the Y direction. The measurement range A1 is provided with three rows of measurement points arranged in the X direction. The distance D1 in the X direction of each measurement point in the measurement range A1 is, for example, 10 to 100 mm, and the distance D2 in the Y direction of each measurement point is, for example, 50 to 150 mm. The measurement range A2 is provided with a row of measurement points arranged in the X direction. The distance D3 in the X direction of each measurement point in the measurement range A2 is, for example, 10 to 100 mm. The number of measurement points per unit area in the measurement ranges A1 and A2 is, for example, 0.03 to 0.8 / cm ² .

The number of displacement sensors 21a to 21g provided on the support base 24 and the arrangement of the displacement sensors 21a to 21g are appropriately set based on the position of the measurement point on the first main surface Ga of the crystallized glass plate G. ing. In the present embodiment, the displacement sensor 21a is a displacement sensor that measures measurement points 1 to 20, the displacement sensor 21b is a displacement sensor that measures measurement points 21 to 40, and the displacement sensor 21c is a displacement sensor that measures measurement points 41 to 60. It is a displacement sensor to measure. The same applies to the displacement sensors 21d to 21g.

Further, in the measurement ranges A1 and A2, a plurality of blocks B1 to B10 that divide the measurement range are set. Blocks B1 to B4 and B7 to B10 that divide the measurement range A1 each include 15 measurement points of 3 × 5 in length, and blocks B5 to B6 that divide the measurement range A2 each include 1 in the vertical direction. × 5 measurement points on the horizontal 5 are included. Information about the position of each measurement point and each block is stored in advance in the control unit 23. In the following, the control unit 23 controls the operations of the displacement sensors 21a to 21g and the moving device 22 so as to measure the height position of the first main surface Ga of the crystallized glass plate G at each of the above measurement points. Then, the control unit 23 measures the warp value of the crystallized glass plate G based on the measured values at each measurement point.

Further, in the control unit 23, when the displacement sensors 21a to 21g pass through the plate thickness measuring unit 14 of the surface plate 11, the heights of the first main surface Ga and the second main surface Gb of the crystallized glass plate G The operation of the displacement sensors 21a to 21g is controlled so as to measure the position. Then, the control unit 23 determines the thickness of the crystallized glass plate G as the difference between the measured height position of the first main surface Ga and the height position of the second main surface Gb. Is calculated.

Hereinafter, a shape measuring method for measuring the amount of warpage of the crystallized glass plate G using the shape measuring device 10 will be described based on the flowchart of FIG. In the present invention, the warp value of the crystallized glass plate G means a value excluding the influence of its own weight.

As step S21, the height position of the first main surface Ga at each measurement point of the crystallized glass plate G is measured. In step S21, first, the crystallized glass plate G is placed on the reference surface 11a of the surface plate 11 of the shape measuring device 10 with the first main surface Ga facing up. At this time, the crystallized glass plate G is placed so that the surface facing the same side in the crystallization step is always the first main surface Ga. In the present embodiment, the crystallized glass plate G is placed so that the main surface facing upward in the crystallization step becomes the first main surface Ga. Further, the crystallized glass plate G is placed so that the axial direction of the roll when the crystalline glass that is the source of the crystallized glass plate G is roll-formed is the Y direction, and the width direction is orthogonal to the molding direction. The measurement range A1 is located on both ends of the glass.

After the crystallized glass plate G placed on the reference surface 11a of the surface plate 11 is moved to the measurement position by using the transport device 13 and the centering mechanism 15, the shape measuring unit 20 at each measurement point shown in FIG. The height position of the first main surface Ga of the crystallized glass plate G is measured.

Further, the plate thickness measuring unit 14 of the platen 11 measures the height positions of the first main surface Ga and the second main surface Gb of the crystallized glass plate G, and the measured first main surface Ga of the crystallized glass plate G is measured. As the difference between the height position of the main surface Ga of 1 and the height position of the second main surface Gb, the plate thicknesses Ta to Tg for each part of the crystallized glass plate G are calculated. The plate thickness Ta is a plate thickness calculated from the measurement result of the displacement sensor 21a. The plate thickness measured by the displacement sensor 21a is a plate thickness in the range of measurement points 1 to 20. The plate thickness Tb is a plate thickness calculated from the measurement result of the displacement sensor 21b. Then, the plate thickness is set in the range of measurement points 21 to 40 measured by the displacement sensor 21b. The same applies to the plate thicknesses Tc to Tg. In the present embodiment, the plate thickness measuring units 14 are provided at two locations on the center side of the surface plate 11 in the X direction, and the crystallized glass plate G measured by the plate thickness measuring portions 14 at the two locations is the first. The average value of the difference between the height position of the main surface Ga of 1 and the height position of the second main surface Gb is defined as the plate thickness Ta to Tg. By providing the plate thickness measuring unit 14 on the center side of the surface plate 11 in the X direction, the influence of the warp of the crystallized glass plate G can be eliminated.

Next, in steps S22 to S25, the direction of warpage for each block is determined, and the warp value for each block is determined based on the determination result. The processes of steps S22 to S25 are performed for all blocks and are performed independently for each block.

Step S22 is a step of determining the direction of warpage in the target block based on the magnitude relationship of the measured values of the measurement points located in the same block. In step S22, the measured value Hs of the reference measurement point (measurement point with the dark dot in FIG. 5 as the background) preset for each block and the comparative measurement point (light dot in FIG. 5) preset for each block are displayed. Compare with the maximum value Hmax of the measured value of the background measurement point).

The comparative measurement point is one or more arbitrary measurement points selected from the measurement points arranged along the edge of the crystallized glass plate G in each block, and in the present embodiment, along the edge of the crystallized glass plate G. All of the measurement points lined up in a row are used as comparative measurement points. The reference measurement point is one or more arbitrary measurement points selected from measurement points other than the measurement points lined up along the edge of the crystallized glass plate G, that is, the measurement points located on the central side of the crystallized glass plate G in each block. It is a measurement point of. When there are a plurality of reference measurement points, the minimum value of the measurement value of the reference measurement point is set as the measurement value Hs of the reference measurement point.

In the present embodiment, in the measurement range A1, for the block located at the corner of the crystallized glass plate G, one measurement point located at the center side corner of the crystallized glass plate G is set as a reference measurement point, and other than the corner. For the block located in, one measurement point located in the center of the row away from the plate edge Gc of the crystallized glass plate G is used as a reference measurement point. Further, for the block in the measurement range A2, one measurement point located on the most central side of the crystallized glass plate G is used as a reference measurement point.

In step S22, when the maximum value Hmax is larger than the measured value Hs (maximum value Hmax> measured value Hs), that is, the first main surface Ga on the edge side of the crystallized glass plate G is the first on the center side. When the block is at a position higher than the main surface Ga, it is determined that the block has a warp (warp Wa shown in FIG. 7) in a concave direction on the upper side, and the process proceeds to step S23.

In step S22, when the maximum value Hmax is the measured value Hs or less (maximum value Hmax ≤ measured value Hs), that is, the first main surface Ga on the edge side of the crystallized glass plate G is the first main surface on the center side. When the block is located at a position lower than the surface Ga, it is determined that the block has a warp (warp Wb shown in FIG. 7) in a direction that is convex upward, and the process proceeds to step S24.

As an example, step S22 for the block B1 will be described. The measurement value Hs of the measurement point 45, which is the reference measurement point of the block B1, and the measurement points 1 to 5, 21, 41, which are the comparison measurement points of the block B1. Compare with the maximum value Hmax of the measured value. Then, when the maximum value Hmax is larger than the measured value Hs, it is determined that the block B1 has a warp in the direction of being concave on the upper side, and when the maximum value Hmax is equal to or less than the measured value Hs, the block B1 , It is determined that the warp is convex upward.

Step S23 is a step of calculating the warp value W1 of the block having the warp in the direction of being concave on the upper side. In the present embodiment, the warp value W1 is calculated as a value (Hmax−T) obtained by subtracting the plate thickness T of the crystallized glass plate G from the maximum value Hmax of the comparative measurement points in the block. The plate thickness T used for calculating the warp value W1 is the plate thickness at the comparative measurement point having the maximum value Hmax, and is selected from the plate thicknesses Ta to Tg calculated in step S21.

Step S24 is a step of calculating the maximum height difference Dmax in the block having a warp in the direction of being convex upward. The maximum height difference Dmax is calculated as the absolute value of the difference between the maximum value and the minimum value of all the measurement points in the target block.

Step S25 following step S24 is a step of calculating an estimated warp value W2 as a warp value of a block having a warp in a direction that is convex upward. The estimated warp value W2 is an estimated value of the warp value of the target block when the crystallized glass plate G is inverted and placed so that the warp direction of the target block is concave upward. The estimated warp value W2 is calculated using the correction information stored in advance in the control unit 23.

The correction information is, for example, a correction formula “W2 = a (Dmax) + b” in which a and b are positive constants and the maximum height difference Dmax is a variable. Correction information such as a correction formula is set based on the result of a preliminary test conducted in advance. The contents of the preliminary test are as follows.

A test glass plate having the same shape obtained by the same manufacturing method as the crystallized glass plate G to be measured is prepared. The test glass plate is subjected to the same processing as in steps S21 to S24 described above, and the warp value W1 or the maximum height difference Dmax of each block is measured. Then, with the test glass plate inverted, the above steps S21 to S24 are performed again to measure the warp value W1 or the maximum height difference Dmax of each block.

By the above measurement, both the warp value W1 and the maximum height difference Dmax can be obtained for each block of the test glass plate. The warp value W1 and the maximum height difference Dmax of the same block are the same values under zero gravity, but the maximum height difference Dmax is slightly smaller due to the bending of the test glass plate due to its own weight.

Here, in the case of the crystallized glass plate G, there is a positive correlation between the warp value W1 and the maximum height difference Dmax. For example, although not shown, such a correlation is shown in a graph in which the maximum height difference Dmax is on the horizontal axis and the warp value W1 is on the vertical axis, and the maximum height difference Dmax and the warp value W1 in each block of the test glass plate are shown. This can be confirmed by creating a scatter plot that plots the relationships.

In the preliminary test, the correlation between the warp value W1 and the maximum height difference Dmax is obtained from the measurement results of the warp value W1 and the maximum height difference Dmax of each block of the test glass plate. Then, based on the correlation, correction information such as a correction formula and a map for converting the maximum height difference Dmax so as to approach the warp value W1 of the same block is derived.

In the preliminary test, it is preferable to use a plurality of test glass plates in order to collect more information on the relationship between the block warp value W1 and the maximum height difference Dmax. In this case, correction information capable of converting the maximum height difference Dmax into the warp value W1 can be obtained with higher accuracy.

In the present embodiment, step S21 is a measurement step, step S22 is a first determination step, and steps S23 to S25 are second determination steps.
(Sorting process)
The sorting step S13 is a step of sorting the crystallized glass plate G based on the measurement result of the shape measuring step S12. The criteria for sorting the crystallized glass plate G can be appropriately set. For example, when the crystallized glass plate G having a large warp is excluded, crystallization is performed based on whether or not all the warp values W1 and the estimated warp values W2 measured in the shape measuring step S12 are equal to or less than a predetermined reference value. Sort the glass plate G. Then, only the crystallized glass plate G in which all the warp values W1 and the estimated warp values W2 are equal to or less than the reference values are selected. The crystallized glass plate G that has undergone the sorting step is subjected to a next step such as a polishing step, if necessary.

Further, when the processing method of the next step is changed based on the size of the warp of the crystallized glass plate G, the maximum values of the warp value W1 and the estimated warp value W2 measured in the shape measurement step S12 are used. The crystallized glass plate G may be sorted based on the crystallized glass plate G, or the crystallized glass plate G may be sorted based on the number or position of blocks in which the warp value W1 and the estimated warp value W2 exceed a predetermined reference value.

Next, the operation of this embodiment will be described.
Conventionally, when measuring the warp value of a glass plate, the magnitude of the warp in the upward convex direction is set as the warp in the upward concave direction by inverting the glass plate in order to eliminate the influence of its own weight. It was necessary to make the measurement again.

In the case of the warp that occurs in the crystallized glass plate G during crystallization, the shape of the warp when measured in the direction of being convex upward and the shape of the warp when the crystallized glass plate G is inverted and measured in the direction of being concave upward are measured. There is a positive correlation with the shape of the warp of the time. Utilizing this correlation, in the shape measurement step of the present embodiment, regarding the warp in the upward convex direction, the value based on the shape measured in the upward convex direction and the correction information based on the above correlation Is used to estimate the warp value based on the shape when the crystallized glass plate G is inverted and measured as a warp in the direction of being concave on the upper side.

Specifically, the crystallized glass plate G is placed on the reference surface 11a, and the reference surface 11a and the first main surface at a plurality of measurement points set in the measurement ranges A1 and A2 of the crystallized glass plate G. After measuring the positional relationship with Ga, the direction of warpage is determined for each block that divides the measurement ranges A1 and A2. Then, for the block determined to have a warp in the upward convex direction, the maximum height difference Dmax of the first main surface Ga of the block is obtained based on the measured value of the measurement point in the target block, and the maximum is obtained. A correction value obtained by correcting the height difference Dmax using the correction information set in advance based on the above correlation is obtained.

The above correction values are the reference surface 11a and the first main surface Ga of the crystallized glass plate G when the crystallized glass plate G is inverted and the warp of the target block is measured as the warp in the direction of being concave upward. The value is close to the positional relationship between and. Therefore, the correction value can be regarded as an estimated value (estimated warp value) of the warp value excluding the influence of its own weight in the warp in the direction of being convex upward. Therefore, the magnitude of the warp can be confirmed without inverting the crystallized glass plate G even for the warp in the direction of being convex upward.

Next, the effect of this embodiment will be described.
(1) In the method for measuring the shape of the crystallized glass plate G, the crystallized glass plate G is placed on the reference surface 11a with the first main surface Ga facing up, and the first main surface of the crystallized glass plate G is placed. Based on the measurement step (step S21) of measuring the height position of the surface Ga at a plurality of points and the measurement result of the measurement step, the direction of warpage of each block is determined for each block in which the crystallized glass plate G is divided. The first determination step (step S22) and the second determination step (steps S23 to S25) of obtaining the warp value for each block according to the direction of the warp of the crystallized glass plate G of the block obtained by the first determination step. And have. In the second determination step (steps S24 to S25), when it is determined in the first determination step (step S22) that the target block has a warp in the direction of being convex upward, the crystallized glass plate in the block is determined. A correction value obtained by correcting the height position of the first main surface Ga of G is obtained, and this correction value is set as the estimated warp value W2 of the block.

According to the above configuration, the magnitude of the warp can be confirmed even for the warp in the upward convex direction without inverting the crystallized glass plate G. Therefore, when the shape of the crystallized glass plate G is measured on the production line, it is not necessary to separately install a reversing device for reversing the crystallized glass plate G in addition to the shape measuring device 10.

(2) In the measurement step, the positional relationship between the first main surface Ga and the reference surface 11a of the crystallized glass plate G is measured at many points on the edge side of the crystallized glass plate G rather than the center side.
The warp of the crystallized glass plate G generated during crystallization tends to be concentrated on the edge side of the crystallized glass plate G. Therefore, by providing many measurement points on the edge side of the crystallized glass plate G, the measurement accuracy is improved. Further, by relatively reducing the number of measurement points on the central side of the crystallized glass plate G, the number of displacement sensors 21a to 21g used in the measurement process can be reduced, the time required for the measurement process can be shortened, and the measurement process can be performed. It is possible to simplify the determination process and the calculation process in each subsequent step.

(3) The crystallized glass plate G is a crystallized glass plate formed by crystallizing a crystalline glass plate formed by roll molding. In the width direction orthogonal to the molding direction at the time of roll molding, more measurement points are provided on the edge side than the center side of the crystallized glass plate G.

The warp of the crystallized glass plate G formed by crystallizing the crystalline glass plate formed by roll molding is concentrated on the portions on both ends in the width direction orthogonal to the molding direction during roll molding. Therefore, the accuracy of measurement is improved by providing many measurement points on the edge sides of the crystallized glass plate G at both ends in the width direction orthogonal to the molding direction at the time of roll molding.

(4) In the first determination step, the measurement value of the comparison measurement point, which is the measurement point located on the edge side of the crystallized glass plate G in the target block, and the measurement value of the reference measurement point selected from the other measurement points. The direction of warpage is determined based on the magnitude relationship with Hs.

According to the above configuration, the direction of warpage for each block can be determined by a simple comparison process.
(5) In the second determination step (step S23), when it is determined that the target block has a warp in the direction of being concave upward, the first main surface Ga of the crystallized glass plate G in the block is determined. The warp value W1 of the block is obtained from the positional relationship with the reference surface 11a and the plate thickness T of the crystallized glass plate G.

According to the above configuration, by a simple calculation process, the warp value W1 of the block having a warp in the direction of being concave on the upper side, that is, between the reference surface 11a and the second main surface Gb of the crystallized glass plate G. The positional relationship can be calculated.

In addition, this embodiment can be implemented by changing as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
-The positions of the measurement ranges A1 and A2 of the first main surface Ga of the crystallized glass plate G may be changed. For example, the entire first main surface Ga of the crystallized glass plate G may be used as the measurement range.

-The arrangement of measurement points provided in the measurement range may be changed. For example, two or four rows or more of measurement points may be arranged in the measurement range A1, or two or more rows of measurement points may be arranged in the measurement range A2. Further, the measurement points may be arranged so as to be evenly distributed within the measurement range.

The method for determining the warp direction of the block is not limited to the comparison of the magnitude relationship between the maximum value Hmax of the measured value at the comparative measurement point and the measured value Hs at the reference measurement point. For example, a three-dimensional model of the first main surface Ga of the target block is created based on the measured values of each measurement point in the target block, and the direction of the block warp can be determined from the three-dimensional model. good.

The warp value W1 was calculated as a value (Hmax-T) obtained by subtracting the plate thickness T of the crystallized glass plate G from the maximum value Hmax of the comparative measurement points in the block, but the maximum value Hmax may be the warp value W3. .. In that case, the estimated warp value W4 may be calculated from the correlation between the warp value W3 and the maximum height difference Dmax.

-The correction information used for calculating the estimated warp value W2 may be correction information common to all blocks as in the above embodiment, or may be correction information set for each block. When the common correction information is used, the calculation process of the estimated warp value W2 can be simplified, and when the correction information is set for each block, the estimation accuracy of the estimated warp value W2 is improved.

The plate thickness T of the crystallized glass plate G used for calculating the warp value W1 may be a preset fixed value.
The warp value W1 of the block determined to have a warp in a concave direction on the upper side may be measured by a known measuring method other than the second determination step (step S23).

-It is not necessary to unify the orientation and front and back of the crystallized glass plate G when the crystallized glass plate G is placed on the reference surface 11a.
-The correlation between the warp shape when the glass plate is measured in the upward convex direction and the warp shape when the glass plate is inverted and measured in the upward concave direction is crystallization, etc. It is present in many post-treated glass plates. Therefore, the method for measuring the shape of the glass plate of the above embodiment can be applied to a glass plate having the above correlation in addition to the crystallized glass plate.

Next, the technical idea that can be grasped from the above-described embodiment and modification is described below.
(A) The first determination step is one selected from the measured values of the comparative measurement points, which are the measurement points located on the edge side of the crystallized glass plate in the target block, and the other measurement points. A method for measuring the shape of a glass plate, which determines the direction of warpage based on the magnitude relationship with the measured value of a reference measurement point.

(B) In the second determination step, the shape of the glass plate having the value obtained by subtracting the plate thickness of the glass plate from the maximum value of the measured values of the comparative measurement points in the target block as the warp value of the block. Measuring method.

(C) A method for measuring the shape of the glass plate, in which more measurement points are provided on both end sides than on the center side in the width direction orthogonal to the molding direction when the glass plate is molded.
(D) A method for producing the glass article, in which the crystallized glass plate is placed on a reference surface so that the surface facing the same side in the crystallization step is always the first main surface.

A1, A2 ... Measurement range B1 to B10 ... Block G ... Crystallized glass plate Ga ... First main surface Gb ... Second main surface 11a ... Reference surface

Claims (4)

The glass plate is placed on the reference surface with the first main surface of the glass plate having the first main surface and the second main surface facing up, and the first main surface of the glass plate is placed. A measurement process that measures the height position at multiple points,
Based on the measurement result of the measurement step, the first determination step of determining the direction of warpage of each block for each block in which the glass plate is divided, and
A second determination step of obtaining a warp value for each block according to the direction of warpage of the glass plate of the block obtained by the first determination step is provided.
The second determination step is
In the first determination step, when it is determined that the target block has a warp in an upwardly convex direction, a correction value corrected for the height position of the first main surface of the glass plate in the block. A method for measuring the shape of a glass plate for obtaining the warp value of the block based on the above. The second determination step is
In the first determination step, when it is determined that the target block has a warp in a concave direction on the upper side, the height position of the first main surface of the glass plate in the target block and the said. The method for measuring the shape of a glass plate according to claim 1, wherein the warp value of the block is obtained from the positional relationship with a reference surface. The glass plate according to claim 1 or 2, wherein the measuring step measures the height position of the first main surface of the glass plate at many points on the edge side of the glass plate from the center side. Shape measurement method. A crystallization step of crystallizing a crystalline glass plate formed by roll molding to obtain a crystallized glass plate,
A method for producing a glass article, comprising a shape measuring step of measuring the amount of warpage of the crystallized glass plate using the method for measuring the shape of a glass plate according to any one of claims 1 to 3.

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