JP2000066001A - Production of grooved planar glass preform, production of glass blank and production of glass optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to exactly form a member to be cut in a process for producing a grooved planar glass preform having a groove which may be cut by impression of a local stress. SOLUTION: The optimum blade edge angle θ of a wheel cutter 161 is determined by θ=a-bβ1+cβ2. The coeffts. a, b, c respectively attain values 100 to 200, 1 to 2, 0.5 to 0.6, more preferably 141.01 to 142, 99, 1, 3 to 1.48, 0.51 to 0.55. In addition, β1 is a parameter indicating the thickness of the planar glass preform and β2 is a parameter indicating the material quality of the planar glass preform. As a result, an adequate crack may be formed at the time of scribing the planar glass preform. The good-quality press blank may be formed after cutting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a grooved plate-like glass base material having grooves that can be cut by applying local stress, a method for manufacturing a glass material, and a method for manufacturing a glass optical element.

[0002]

2. Description of the Related Art When forming optical elements such as optical lenses and prisms, press molding is used. As the press molding method, there are mainly a direct press method and a reheat press method. The direct press method is a method in which a molten glass body is directly pressed by an upper mold and a lower mold. However, in this method, since the surface accuracy of the pressed product is not good, it is necessary to grind after pressing.

On the other hand, in the reheat press method, first, a press material having a weight after molding is obtained, and the surface of the press material is polished to form a preform. Next, the preform is reheated (reheated) to a softened state, and pressed with a molding die. According to this reheat press method, since the glass surface after forming has high precision, there is no need for polishing. However, if the softened glass does not correctly fit in the space of the mold, reproducibility with respect to the mold deteriorates. Therefore, it is necessary to form the press material so that the weight is always constant.

[0004] Generally, a press material used in the reheat press method is obtained by cutting a sheet glass base material. As one of the cutting methods, there is a method of scribing the main surface of a sheet glass base material using a carbide wheel cutter. FIG. 10 is a side sectional view showing a scribing method of a sheet glass base material. FIG. 11 is a view of the cutter in the scribing method as viewed from the front side. FIG. 12 is a diagram showing a specific shape of the groove formed in the sheet glass base material. In this method, a carbide wheel cutter 51 having a cutting edge angle θ1 advances on the main surface 50a of the sheet glass base material 50 in the direction of the arrow in FIG.
To form The formation of the groove 52 causes a crack. The cracks include a vertical crack 53 perpendicular to the main surface 50a and horizontal cracks 54 and 55 substantially parallel to the main surface 50a. Further, a surface crack 56 as shown in FIG. 12 also occurs.

After the formation of the groove 52, for example, Japanese Patent Application No. 9-35-9
No. 9522, the vertical crack 53
The plate-shaped glass base material 50 is placed on the mounting table such that the main surface 50a formed with the surface faces downward, and a predetermined load is applied to a position facing the vertical crack 53 on the opposite main surface 50b side. As a result, the vertical cracks 53 grow, and the tensile stress F1 of the vertical cracks 53 also helps to cut the plate-like glass base material 50.

[0006]

However, if the glass type or shape of the glass preform differs, the manner in which cracks 53 and the like occur differs. Therefore, even if the same carbide wheel cutter is used and scribing is performed with a quantitatively determined pressing force, it is not always possible to form a preferable crack. Therefore, a member to be cut could not be obtained with high accuracy.

[0007] The present invention has been made in view of the above points, and a method of manufacturing a grooved plate-shaped glass base material, a method of manufacturing a glass material, and glass capable of always forming an accurate member to be cut. An object of the present invention is to provide a method for manufacturing an optical element.

[0008]

According to the present invention, in order to solve the above problems, a step of pressing a cutter on one main surface of a sheet glass base material to form a groove including at least a vertical crack is performed. In the method for manufacturing a grooved plate-like glass base material having a groove capable of cutting the plate-like glass base material by local stress, in the step, the vertical cracks may be deeper than horizontal cracks. The present invention provides a method for manufacturing a grooved plate-like glass base material, wherein the blade edge angle of the cutter is selected in consideration of the thickness and the material of the glass base material.

In such a method of forming a sheet glass base material, the cutting edge angle of the cutter is selected in consideration of the thickness and the material of the sheet glass base material so that a vertical crack is deeper than a horizontal crack. .

Since the vertical cracks are formed so as to be deeper than the horizontal cracks, it is possible to always form an accurate cut member.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a plan view showing a schematic configuration of the scribing device. A table 12 is mounted on a base 11 of a scribing device 10 used in the present embodiment so as to be slidable in the Y-axis direction. The movement of the table 12 is controlled by a Y-axis drive motor 13.
On the table 12 is an acrylic plate 12 for running the cutter.
a and 12b are fixed. The acrylic plate 12
The plate-shaped glass base material 20 is placed so as to be in close contact with the inner surfaces of the a and 12b. The plate-shaped glass preform 20 is an optical glass preform, and particularly a glass preform as a material of a press material for an optical element as described later. One corner P0 of the sheet glass base material 20 is set at the origin of scribing.

The base 11 is provided with a cutter mechanism 14. An up-down movement mechanism 15 and a cutter unit 16 are integrally mounted on the cutter mechanism 14 so as to be slidable in the X-axis direction. Cutter unit 16
Scribes the glass preform 20 by the wheel cutter as described later, and moves up and down by the operation of the up-down movement mechanism 15. The vertical movement mechanism 15 and the cutter unit 16 are connected to the X-axis drive motor 1.
7, the movement is controlled.

The drive of the X-axis drive motor 17 and the Y-axis drive motor 13 is controlled by a controller (not shown). FIG. 3 is a side view showing the configuration of the cutter unit 16. A wheel cutter 16 is attached to a fixing member 160 connected to the vertical movement mechanism 15 via a holder 162.
1 is attached. The holder 162 has its shaft 16
2a is attached to the fixing member 160 via the bearing 163. Thereby, the wheel cutter 161 is rotatable around the vertical direction of the blade.

The cutter unit 16 is provided with a pressurizing cylinder 164. This pressurizing cylinder 164
Is for adjusting the pressing load of the wheel cutter 161 when scribing the glass preform 20.
This pressing load is appropriately adjusted according to various conditions as described later.

FIG. 1 is a diagram showing the shape of the wheel cutter 161 of the present embodiment. Here, a state viewed from a direction perpendicular to the rotation axis of the wheel cutter 161 is shown. The wheel cutter 161 is a carbide wheel cutter, and its cutting edge 161a is symmetric on both sides. The angle θ of the cutting edge 161a is appropriately selected according to various conditions as described later.

In the scribing apparatus 10 according to the present embodiment having such a configuration, the X-axis drive motor 17 and the Y-axis drive motor 13 shown in FIG.
The cutter unit 16 is positioned with respect to 0, and the amount of cutting of the wheel cutter 161 into the sheet glass base material 20 is controlled by the vertical movement mechanism 15. And
While rotating the wheel cutter 161, the table 12
By moving the cutter unit 16 relatively, scribing to the surface of the sheet glass base material 20 is performed.

FIGS. 4A and 4B are diagrams showing examples of the shape of the glass preform 20 after scribing, wherein FIG. 4A is a plan view and FIG.
Is a side view. Here, an example is shown in which 18 grooves D1 to D18 are formed in the upper main surface 21 of the two main surfaces 21 and 22 of the sheet glass base material 20. Groove D1
D18 are formed in a grid at equal intervals. Each of the grooves D1 to D18 is formed such that a crack substantially perpendicular to the main surface as shown in FIGS.

The plate-shaped glass base material 20 having such grooves is cut by a plate-shaped glass base material cutting device.
FIG. 5 is a plan view showing a configuration near a mounting table of the plate-shaped glass base material cutting device. FIG. 6 is a sectional view taken along line A1-A1 in FIG. The plate glass preform cutting device 30 is provided with a mounting table 31 on which the plate glass preform 20 is mounted. The mounting table 31 is provided so as to be able to reciprocate in the X-axis direction in FIG. At the start of the operation, the mounting table 31 is arranged such that its center point P1 coincides with the origin of the XY coordinate system. Further, the mounting table 31 has a center point P
1 is provided so as to be rotatable in an XY plane about an axis. The movement and rotation of the mounting table 31 are executed by a driving mechanism (not shown) provided on the back side of the mounting table 31.

On the mounting table 31, a reference plate 32 is fixed. The reference plate 32 is an L-shaped member, and has positioning members 3 on its inner surfaces 32a and 32b.
3, 34 are fixed. Positioning members 33, 34
Is formed of an elastic material such as natural rubber so that chipping or the like does not occur when the sheet glass base material 20 is cut.

On the mounting table 31, a substantially square plate-shaped cutting auxiliary member 40 is mounted. The cutting auxiliary member 40 is pressed against the positioning members 33 and 34 of the reference plate 32 by the pressing device 37 and the pressing device 38. Pressing plate 37 of pressing device 37
A positioning member 35 made of natural rubber is fixed to a. The pressing device 37 is provided with the positioning member 3.
At 5, the cutting auxiliary member 40 is pushed in the X-axis direction, and is pressed against the positioning member 33 of the reference plate 32.

Similarly, the pressing plate 3 of the pressing device 38
A positioning member 36 made of natural rubber is fixed to 8a. The pressing device 38 includes a positioning member 36.
Press the cutting auxiliary member 40 in the Y-axis direction with the reference plate 3
2 is pressed against the positioning member 34 side. Thus, the cutting auxiliary member 40 is positioned and fixed on the mounting table 31.

On the cutting auxiliary member 40, a cutting auxiliary member 4
A sheet glass base material 20 slightly smaller than 0 is placed.
The plate-shaped glass base material 20 is placed so that the main surface 21 on which the above-described grooves D1 to D18 are formed faces downward, and is in close contact with the positioning members 33 and 34 side. At this time,
As shown in FIG. 6, the plate-shaped glass base material 20 is positioned by a predetermined length from the upper main surface 22 by a predetermined length.
It protrudes from the upper side of 5,36. Further, since the sheet glass preform 20 is smaller than the cutting auxiliary member 40, the sheet glass preform 20 and the positioning members 35 and 36 are provided.
And a moderate gap (here, for example, 0.1 mm)
Is emptied. The clearance secures an escape space for the glass at the time of cutting.

In the mounting table 31, the dimensions of the members are set such that the center of the glass substrate 20 coincides with the center point P 1 of the mounting table 31 when the glass substrate 20 is mounted. Designed.

A pressurizing device 39 is provided above the mounting table 31, as shown in FIG. The indenter table 390 of the pressing device 39 is connected to the axis of the Z-axis servo motor 392 via a ball screw 392a. The indenter table 390 is
It moves up and down along the Z axis by the rotation of the Z axis servomotor 392. A round bar-shaped indenter 391 extending in the Y-axis direction is fixed to the lower surface 390a of the indenter table 390. Indenter 3
Reference numeral 91 denotes a member that presses and cuts the plate-like glass base material 20 from above, and has substantially the same length as the groove of the plate-like glass base material 20 as described later.

In the sheet glass preform cutting device 30 having such a configuration, when starting the cutting operation, the center point P1 of the mounting table 31 is located at the origin of the XY coordinates. On the other hand, the pressing device 39 is located at a position sufficiently higher than the mounting table 31 as shown in FIG. At this time, the mounting table 31 is set so that the first cut groove (for example, the groove D5) of the sheet glass base material 20 coincides with the Y axis, that is, the indenter 391 of the pressing device 39 and the
The position and the orientation are controlled so as to be overlapped on the -Y plane.

When the positioning is completed, the Z-axis servo motor 392 operates and the indenter 391 descends, and comes into contact with a position on the main surface 22 of the sheet glass base material 20 facing the groove D5. When the indenter 391 further descends from this state, a local stress is applied to a position facing the groove D5, and the groove D5
Cracks are enlarged and cut. For other grooves,
Cutting is performed by the same positioning and pressing operations, and finally, a total of 100 press materials are formed. In addition,
Here, the local stress is a stress caused by pressure or heat locally applied from the outside, a force or heat applied from the outside concentrated on the groove portion, and a vertical The local tensile stress (F1 shown in FIG. 12) generated at the tip of the crack includes one that increases due to externally applied pressure or heat.

The formed press material is press-molded in a state where it is softened by heating to form a glass optical element. The glass optical element is, for example, a lens or a prism, and includes not only a glass optical element manufactured by performing polishing and grinding after press molding, but also a precision press that does not perform polishing and grinding after press molding.

By the way, the quality of the press material is based on a uniform weight without chipping. For this purpose, it is important that a suitable crack is formed at the scribing stage. At this time, a horizontal crack is generated together with the vertical crack. However, in order to grow the vertical crack and cut it accurately, it is important that the vertical crack is deeper than the horizontal crack. Among them, a suitable crack is a crack in which a tensile stress generated by the pressing force of the wheel cutter 161 is generated, and more preferably a crack in which the crack is more strongly left. If the tensile stress that the crack itself tries to open is large, the load for cutting can be reduced, so that chipping of the glass can be prevented. Also, if the tensile stress is large, even if no bending moment is generated at the cut part,
Alternatively, even if the bending moment is extremely small, cutting can be performed, so that the amount of displacement of the glass preform 20 can be reduced. Accordingly, interference between the glass materials is eliminated, and chipping after cutting and scratching of the surface are prevented.

Further, cracks perpendicular to the main surface are preferably deep. In particular, it is important to be deeper than a horizontal crack which is one of the causes of chipping of glass. If the vertical crack is deep, the load for generating local stress for cutting can be reduced, and if the vertical crack is deeper than the horizontal crack, chipping of the glass can be reliably prevented.

Such a suitable crack can be obtained by setting the cutting edge angle θ of the wheel cutter 161 and the pressing load at the time of scribing to optimal values. Next, a method of setting the cutting edge angle θ of the wheel cutter 161 for forming a groove having a suitable crack and a pressing load at the time of scribing will be described.

First, the cutting edge angle θ of the wheel cutter 161
In order to determine the value, scribing and cutting were performed on plate-shaped glass members made of three types of materials by changing the thicknesses of the plate-shaped glass members using wheel cutters having various cutting edge angles. And
The cutting edge angle θ of the wheel cutter from which a good press material was obtained was examined.

FIG. 7 is a diagram showing the optimum cutting edge angles of the wheel cutters in the sheet glass base material of various materials. Here, the test was performed with the pressing load of the wheel cutter 161 kept constant. The cutting amount of the wheel cutter 161 on the glass surface and the speed of the wheel cutter 161 during scribing are constant (for example, the cutting amount is 0.05 mm and the scribing speed is 250 mm /
sec).

The material of the plate-like glass base material 20 includes boric acid-lanthanum type (characteristic L1) and borosilicate type (characteristic L1).
2), three kinds of glass of silica-lead type (characteristic L3) are selected, and the thickness of each material is 4 (mm);
6 (mm) and 8 (mm) sheet glass base materials were scribed and cut. Thus, the cutting edge angle θ at which the optimum press material is obtained is shown in the figure. Here, the criterion for determining the optimum press material is that the formed press material has a small variation in weight, and the rib mark depth (vertical crack depth) of the cut surface is 0.5 to 0.6 (mm). That is about.

As a result, it was found that the optimum cutting edge angle θ of the wheel cutter 161 can be expressed by the following equation (1).

[0035]

[Mathematical formula-see original document] [theta] = ab- [beta] ₁ + c [beta] ₂ (1) Here, [beta] ₁ represents the thickness of the plate-like glass base material 20, and [beta] ₂ represents the material of the plate-like glass base material 20. Parameter. Also,
The coefficients a, b, and c are positive numbers. From this equation, it can be seen that the optimum cutting edge angle θ is preferably reduced as the thickness of the glass base material 20 is increased, and is preferably increased as the parameter indicating the material of the glass base material 20 is increased.

Here, the parameters indicating the material are as follows:
Rigidity, hardness, degree of wear, Young's modulus, etc. can be applied. When the rigidity is used as the parameter, the coefficient a is 100 to 200, the coefficient b is 1 to 2, and the coefficient c is 0.5 to
0.6. With this setting, a vertical crack deeper than the horizontal crack is formed,
Tensile stress that can cut the glass without causing chipping remains in the vertical crack. Further, in order to obtain such an effect higher, the coefficients a, b, and c are 141.01 to 142.99, 1.3 to 1.48, and 0.
It is preferably 51 to 0.55.

Subsequently, a similar test was performed to determine the optimum pressing load of the wheel cutter 161. FIG.
FIG. 3 is a diagram showing an optimum pressing load of a wheel cutter on a sheet glass base material of various materials. Here, similarly to the case of the cutting edge angle, the cut amount of the wheel cutter 161 into the glass surface and the speed of the wheel cutter 161 at the time of scribing are constant (for example, the cut amount is set to 0. 1).
05 mm and a scribe speed of 250 mm / sec).

Further, as the material of the sheet glass base material 20, a boric acid-lanthanum glass (characteristic L4), a borosilicate glass (characteristic L5), and a silica-lead glass (characteristic L6) are selected. About 4 (mm), 6 (m
m) and 8 (mm) sheet glass preforms were scribed and cut. Thus, the pressing load obtained for the optimum press material is shown in the figure. In addition, as for the criterion for determining the optimum press material, the variation in the weight of the formed press material is small (specifically, ± 5 wt%) and the rib mark on the cut surface, as in the case of the cutting edge angle. Depth (vertical crack depth) 0.5-0.6
(Mm).

Further, from the results shown in FIG. 8, it can be seen that the difference in sheet thickness has almost no effect on the pressing load. Therefore, rigidity (GPa) / specific gravity (kg · m ⁻² ) was selected as a parameter for determining the optimal pressing load, and the relationship between this rigidity / specific gravity and the optimal pressing load was examined. This is shown in FIG.

Based on the results of FIG. 9, it was found that the optimum pressing load W of the wheel cutter 161 can be expressed by the following equation (2).

[0041]

W = d + e · α (2) where α is a parameter / specific gravity indicating the material of the sheet glass base material 20. The coefficients d and e are positive numbers. From this equation, it is preferable that the optimum pressing load W be smaller as the specific gravity of the glass base material 20 is larger.
It can be seen that the larger the parameter indicating the material of 0, the better.

Here, the parameters indicating the material are as follows:
Rigidity, hardness, degree of wear, Young's modulus, etc. can be applied. When the rigidity is used as the parameter, the coefficient d,
e is 0.15 to 0.3 and 0.001 to 0.0, respectively.
3, preferably 0.171 to 0.246, 0.0
06 to 0.014.

Based on the equations (1) and (2) obtained as described above, the cutting edge angle θ of the wheel cutter 161 is obtained.
And the pressing load W at the time of scribing are determined, and scribing is performed by the scribing device 10 in accordance with the determined scribing load, whereby a suitable vertical crack can be formed. Thereby, a high-quality press material can be obtained in a large amount at high speed.

In this embodiment, an example is shown in which grooves are formed in the plate-like glass base material 20 for forming a press material, but the grooves are used for cutting when manufacturing a flat display glass substrate such as a liquid crystal display. The present invention can also be applied to the formation of a groove.

In this embodiment, an example is shown in which the wheel cutter 161 is used as a tool for forming a groove.
A rectangular cutter or the like may be used.

[0046]

As described above, in the present invention, the edge angle of the cutter is selected in consideration of the thickness and the material of the sheet glass base material so that the vertical crack is deeper than the horizontal crack. Therefore, a vertical crack under optimal conditions can be formed.

Therefore, an accurate member to be cut can always be formed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a shape of a wheel cutter of the present embodiment.

FIG. 2 is a plan view showing a schematic configuration of a scribing device.

FIG. 3 is a side view illustrating a configuration of a cutter unit.

4A and 4B are diagrams showing examples of the shape of a sheet glass base material after scribing, wherein FIG. 4A is a plan view and FIG. 4B is a side view.

FIG. 5 is a plan view showing a configuration near a mounting table of the sheet glass preform cutting apparatus.

FIG. 6 is a sectional view taken along line A1-A1 of FIG.

FIG. 7 is a diagram showing optimum cutting edge angles of a wheel cutter in a sheet glass base material of various materials.

FIG. 8 is a view showing an optimum pressing load of a wheel cutter on a sheet glass base material of various materials.

FIG. 9 is a diagram showing a relationship between a rigidity and an optimal pressing load.

FIG. 10 is a side sectional view showing a scribing method of a sheet glass base material.

FIG. 11 is a front view of a cutter in a scribing method.

FIG. 12 is a view showing a specific shape of a groove formed in a sheet glass base material.

[Explanation of symbols]

 Reference Signs List 10 scribing device 12 table 16 cutter unit 20 sheet glass base material 21, 22 main surface 30 sheet glass base material cutting device 161 wheel cutter 164 pressure cylinder

Claims (13)

[Claims] 1. A step of pressing a cutter on one main surface of a sheet glass base material to form a groove including at least a vertical crack, thereby cutting the sheet glass base material by local stress. In the method for manufacturing a grooved plate-like glass base material having grooves that can be formed, in the step, the thickness and the material of the plate-like glass base material are taken into consideration, so that the vertical cracks are deeper than the horizontal cracks. A method for manufacturing a grooved plate-shaped glass base material, wherein a cutting edge angle of a cutter is selected. 2. The method according to claim 1, wherein any one of rigidity, hardness, abrasion, and Young's modulus is used as a parameter for determining the material. . 3. When the cutting edge angle is θ, the plate thickness is β ₁ , a parameter value indicating the material is β ₂ , and a, b, and c are positive coefficients, θ = ab−b · The method according to claim 1, wherein the blade edge angle is set to be β ₁ + c · β ₂ . 4. A method according to claim 1, wherein a rigidity is used as a parameter β ₁ indicating said material, and said coefficient a is 100 to 200;
The method according to claim 3, wherein the coefficient b is 1 to 2, and the coefficient c is 0.5 to 0.6. 5. The grooved sheet glass mother according to claim 1, wherein a pressing load of the cutter against the sheet glass base material is set based on a value / specific gravity of a parameter indicating the material. The method of manufacturing the material. 6. When the pressing load of the cutter against the plate-like glass base material is W, the value / specific gravity of a parameter indicating the material is α, and d and e are positive coefficients, W = d + e.
The method according to claim 1, wherein the pressing load is set so as to be α. 7. The method according to claim 1, wherein a rigidity is used as a value of the parameter indicating the material, and the coefficient d is 0.15 to 0.3 and the coefficient e is 0.01 to 0.03. 7. The method for producing a grooved plate-shaped glass base material according to item 6. 8. The method according to claim 1, wherein the glass preform is an optical glass preform. 9. A step of pressing a cutter on one main surface of the sheet glass base material to form a groove including at least a vertical crack, thereby cutting the sheet glass base material by local stress. In the method for producing a grooved plate-like glass base material having grooves that can be formed, in the step, the blade edge angle is θ, the plate thickness of the plate-like glass base material is β ₁ , the value of a parameter indicating the material is β ₂ ,
When a, b, and c are positive coefficients, θ = ab
β ₁ + c · β ₂ and the parameter β ₁
The coefficient a is 100 to 200, and the coefficient b is
And the coefficient c is set to 0.5 to 0.6 to set the cutting edge angle, wherein a grooved plate-shaped glass base material is manufactured. 10. A method for producing a plurality of glass materials by dividing a plate-like glass base material, wherein a vertical crack is deeper than a horizontal crack in consideration of the thickness and material of the plate-like glass base material. A cutter having an edge angle is selected, and using the selected cutter, a groove is formed such that a vertical crack is generated on one main surface of the plate-like glass base material to produce a grooved plate-like glass base material. A method for producing a glass material, comprising: applying a local stress to a groove of the grooved sheet glass base material to grow the vertical crack, thereby performing the division. 11. The local stress is applied by applying a local pressure to a portion of the other main surface of the grooved plate-like glass base material facing the vertical crack. The method for producing the glass material described in the above. 12. The method according to claim 1, wherein the glass material is a press material used in a reheat press method.
0. The method for producing a glass material according to item 0. 13. A method for manufacturing a glass optical element by a reheat press method, wherein a cutter having a cutting edge angle such that a vertical crack is deeper than a horizontal crack is selected in consideration of the thickness and the material of a plate-like glass base material. Using the selected cutter, forming a groove so that a vertical crack occurs on one main surface of the plate-like glass base material to produce a grooved plate-like glass base material; Applying a local stress to the groove of the base material to grow the vertical cracks and divide them to form a glass material as a press material; heat-soften the glass material; and press-mold the glass material. Device manufacturing method.