WO2021157305A1

WO2021157305A1 - Method for manufacturing glass plate

Info

Publication number: WO2021157305A1
Application number: PCT/JP2021/000871
Authority: WO
Inventors: 剛志奥野
Original assignee: 日本電気硝子株式会社
Priority date: 2020-02-05
Filing date: 2021-01-13
Publication date: 2021-08-12
Also published as: JP2021123518A; TW202138321A; CN114845964A; KR20220137872A

Abstract

A method for manufacturing a glass plate, comprising an initial crack formation step for forming an initial crack 2 which serves as a starting point for cleavage in a curved mother glass plate 1, and a laser irradiation step for radiating a laser 4 to the mother glass plate 1 from a laser head 3 and thereby causing a crack 5 to develop along an intended cleavage line 6, starting at the initial crack 2, wherein, in the laser irradiation step, using the laser 4 for heating the inside and a surface section of the mother glass plate 1, the crack 5 is caused to develop along the intended cleavage line 6 by thermal shock that accompanies laser 4 irradiation, and the crack 5 is caused to develop along the thickness direction of the mother glass plate 1, thereby cleaving the mother glass plate 1.

Description

Glass plate manufacturing method

The present invention relates to a method for manufacturing a glass plate.

A 3D-shaped glass plate that is curved vertically and horizontally may be used as the cover glass for smartphone displays and in-vehicle displays. In manufacturing such a glass plate, as an example, the glass plate is cut out from a curved mother glass plate (a glass plate including a 3D-shaped glass plate for a plurality of surfaces) which is the basis of the glass plate.

Here, as one of the methods for cutting a glass plate, laser cutting as disclosed in Patent Document 1 is known.

In laser cutting, when cutting a glass plate along a set scheduled cutting line, first, a diamond cutter or the like is used to form an initial crack in the glass plate, which is the starting point of the cutting. After that, the glass plate is irradiated with a carbon dioxide laser from the laser head, and the refrigerant (air or the like) is injected toward the portion heated by the laser irradiation. At this time, the glass plate is cut by propagating the crack along the planned cutting line starting from the initial crack by the thermal shock applied to the glass plate.

Japanese Unexamined Patent Publication No. 2011-116611

By the way, when the above-mentioned form of laser cutting is used in cutting the above-mentioned curved mother glass plate, the following problems to be solved have occurred.

That is, when the mother glass plate is irradiated with a carbon dioxide gas laser, only the surface layer portion of the mother glass plate (the surface layer portion on the laser incident surface side) is heated by the laser. In the carbon dioxide laser that can heat only the surface layer portion as described above, the range of irradiation conditions that can cut the entire thickness of the mother glass plate is extremely narrow. For example, if the distance between the laser head and the mother glass plate is slightly deviated from the optimum distance, the thermal shock is insufficient and cutting becomes difficult. Therefore, it is very difficult to maintain the laser irradiation condition at a condition that enables cutting of the entire thickness from the start to the completion of cutting the curved mother glass plate. As described above, as a result of difficulty in cutting the entire thickness, a separate folding or the like is required for cutting the mother glass plate, and the property of the cut surface of the glass plate cut out from the mother glass plate tends to deteriorate accordingly. was there.

The present invention made in view of the above circumstances has a technical problem of improving the properties of the cut surface of the glass plate cut out from the mother glass plate when cutting the curved mother glass plate by laser cutting.

The method for manufacturing a glass plate according to the present invention for solving the above problems includes an initial crack forming step of forming an initial crack that is a starting point of fracture in a curved mother glass plate, and a laser from a laser head to the mother glass plate. It is a method including a laser irradiation step in which a crack is propagated along a planned cutting line starting from an initial crack by irradiating. In the laser irradiation step, a laser that heats the surface layer portion and the inside of the mother glass plate is provided. It is characterized in that the crack is propagated along the planned cutting line by the thermal impact accompanying the irradiation of the laser, and the mother glass plate is split by extending along the thickness direction of the mother glass plate.

In this method, a laser that heats the surface layer and the inside of the mother glass plate is used in the laser irradiation step. In this way, in a laser that can heat the inside in addition to the surface layer, it is possible to apply thermal shock not only to the surface layer but also to the inside, so the range of laser irradiation conditions that can cut the entire thickness of the mother glass plate. Is wide. As a result, the laser irradiation condition can be easily maintained at a condition that enables cutting of the entire thickness from the start to the completion of cutting the curved mother glass plate. Therefore, it is possible to cut the entire thickness of the mother glass plate without difficulty in the entire section of the planned cutting line. As a result, the properties of the cut surface of the glass plate cut out from the mother glass plate can be improved.

In the above method, in the laser irradiation step, it is preferable to move the laser head and the mother glass plate relative to each other after keeping the inclination of the axis of the laser head constant.

As mentioned above, in the laser that heats the surface layer and the inside of the mother glass plate, the range of irradiation conditions that can cut the entire thickness of the mother glass plate is wide. Therefore, when cutting the mother glass plate, when scanning the mother glass plate curved by the laser by moving the laser head and the mother glass plate relative to each other, it is necessary to change the inclination of the axis of the laser head according to the curvature. Even if it is not performed, it is possible to cut the entire thickness. Therefore, the inclination of the shaft may be constant, and as a result, a mechanism for changing the inclination of the shaft of the laser head can be eliminated, so that the equipment cost can be reduced. Further, since it is not necessary to change the inclination of the shaft, the time required for cutting the mother glass plate can be shortened.

In the above method, in the laser irradiation step, it is preferable to move the laser head and the mother glass plate relative to each other after keeping the position of the laser head in the axial direction constant.

As mentioned above, the above laser has a wide range of irradiation conditions that can cut the entire thickness of the mother glass plate. As a result, when cutting the mother glass plate, it is possible to cut the entire thickness without changing the position of the laser head in the axial direction according to the curvature of the mother glass plate. Therefore, the position in the axial direction may be constant, and as a result, a mechanism for changing the position in the axial direction can be eliminated, so that the equipment cost can be further reduced. In addition, since it is not necessary to change the position in the axial direction, the time required for cutting the mother glass plate can be further shortened.

In the above method, it is preferable to use a CO laser as the laser in the laser irradiation step.

In this way, the output of the CO laser is high and the mother glass plate can be stably irradiated, so that cracks can be stably propagated along the planned cutting line.

In the above method, the laser irradiation step can be executed under the condition that _{the thermal stress σ T} (MPa) of the mother glass plate calculated by the following equation [Equation 1] satisfies the following equation [Equation 2]. preferable.

However, E is the Young's modulus (MPa) of the mother glass plate, α is the coefficient of thermal expansion (/ K) of the mother glass plate, ν is the Poisson's ratio of the mother glass plate, and ΔT is the temperature at the laser irradiation position on the mother glass plate. It is the difference between (K) and the temperature (K) at a separated position away from the irradiation position.

However, t is the thickness (mm) of the mother glass plate.

By doing so, it is possible to further improve the properties of the cut surface of the glass plate cut out from the mother glass plate.

In the above method, in the laser irradiation step, at least one of (1) the distance between the laser head and the mother glass plate and (2) the angle of incidence of the laser on the surface of the mother glass plate may be changed. ..

Since the above laser has a wide range of irradiation conditions capable of cutting the entire thickness of the mother glass plate, even if one or both of the above (1) and (2) are changed, the total thickness can be changed. Can be cut. That is, in order to cut the entire thickness, it is not necessary to strictly control the above (1) and (2) during the execution of the laser irradiation step.

According to the present invention, when cutting a curved mother glass plate by laser cutting, it is possible to improve the properties of the cut surface of the glass plate cut out from the mother glass plate.

It is a perspective view which shows the initial crack formation process in the manufacturing method of a glass plate. It is a perspective view which shows the laser irradiation process in the manufacturing method of a glass plate. It is sectional drawing which shows the laser irradiation process in the manufacturing method of a glass plate. It is a figure which shows the laser irradiation condition in a laser irradiation process. It is sectional drawing which shows the laser irradiation process in the manufacturing method of a glass plate. It is sectional drawing which shows the laser irradiation process in the manufacturing method of a glass plate. It is a figure which shows the relationship between the thermal stress and the thickness of a mother glass plate.

Hereinafter, the method for manufacturing a glass plate according to the embodiment of the present invention will be described with reference to the attached drawings. The X, Y, and Z directions shown in the drawings referred to in the description of the embodiment are directions orthogonal to each other. The X and Y directions are horizontal, and the Z direction is vertical.

The method for manufacturing the glass plate according to the embodiment includes an initial crack forming step (FIG. 1) for forming an initial crack 2 which is a starting point of cutting on the curved mother glass plate 1, and a laser head 3 to the mother glass plate 1. By irradiating the laser 4, the laser irradiation step (FIGS. 2 and 3) for advancing the crack 5 along the planned cutting line 6 starting from the initial crack 2 is provided.

In the present embodiment, the mother glass plate 1 is divided into the first glass plate 7 and the second glass plate 8 by dividing the mother glass plate 1 along the planned division line 6. The planned cutting line 6 is located at the center of the mother glass plate 1 in the Y direction, and the mother glass plate 1 is formed in a symmetrical shape with respect to the planned cutting line 6. One end of the scheduled cutting line 6 is a start point 6a for starting the cutting of the mother glass plate 1, and the other end is an end point 6b for ending the cutting.

As shown in FIG. 1, the mother glass plate 1 is curved in both the X direction and the Y direction, and has a 3D shape in which the upper surface 1a of the upper and lower surfaces 1a and 1b is convex. The mother glass plate 1 has a rectangular shape in a plan view (viewed from the Z direction). In the present embodiment, the planned division line 6 extends in the X direction in a plan view. Due to the curvature of the mother glass plate 1, a height difference H (difference in height along the Z direction) is generated on the upper surface 1a along the planned cutting line 6. More specifically, the height of the upper surface 1a is the lowest at the start point 6a and the end point 6b of the scheduled cut line 6, and the height of the upper surface 1a is the highest at the midpoint 6c of the scheduled cut line 6. The height difference H is, for example, 20 mm or less, preferably 10 mm or less. In this embodiment, the height difference H is 10 mm.

The thickness of the mother glass plate 1 is 0.05 mm to 5 mm as an example. As will be described in detail later, in the present embodiment, a CO laser is used as the laser 4 to irradiate the mother glass plate 1, and the mother glass plate 1 having a larger thickness than, for example, a carbon dioxide gas laser is used. It is possible to disconnect. Therefore, the thickness of the mother glass plate 1 is preferably more than 0.1 mm, more preferably more than 0.2 mm, and even more preferably more than 0.3 mm. On the other hand, the thickness of the mother glass plate 1 is preferably 3 mm or less. In the present embodiment, the thickness of the mother glass plate 1 is 0.7 mm.

The mother glass plate 1 may be silicate glass, silica glass, borosilicate glass, soda glass, soda-lime glass, aluminosilicate glass, non-alkali glass, or the like. Here, the "non-alkali glass" is a glass that does not substantially contain an alkaline component (alkali metal oxide), and specifically, a glass having a weight ratio of an alkaline component of 3000 ppm or less. .. The weight ratio of the alkaline component is preferably 1000 ppm or less, more preferably 500 ppm or less, and most preferably 300 ppm or less. The mother glass plate 1 may be aluminosilicate glass before chemical strengthening, or the glass plate obtained by the initial crack forming step and the laser irradiation step may be chemically strengthened.

In the initial crack forming step shown in FIG. 1, first, the mother glass plate 1 is placed in a flat position on a support table 9 having a flat support surface 9a. After that, an initial crack 2 is formed on the placed mother glass plate 1 at a position on the upper surface 1a where the start point 6a of the planned split line 6 is located.

When forming the initial crack 2, the crack forming member 10 is used. In this embodiment, a tip-shaped scriber (sintered diamond cutter or the like) is used as the crack forming member 10. Of course, this is not limited to this, and a diamond pen, a cemented carbide cutter, sandpaper, or the like may be used as the crack forming member 10. The initial crack 2 is formed by lowering the crack forming member 10 from above and bringing it into contact with the upper surface 1a of the mother glass plate 1.

Here, in the present embodiment, the initial crack 2 is formed on the upper surface 1a (convex surface) of the upper and lower surfaces 1a and 1b of the mother glass plate 1, but this is not limited to this, and the lower surface 1b (concave) is formed. The initial crack 2 may be formed on the surface). Further, the initial crack 2 may be formed on the end surface of the mother glass plate 1.

In the laser irradiation step shown in FIGS. 2 and 3, the laser 4 is irradiated toward the initial crack 2 located at the start point 6a of the scheduled cutting line 6, and the mother glass plate 1 is irradiated along the scheduled cutting line 6 from that state. Is scanned by the laser 4.

When scanning the laser 4, the inclination of the axis of the laser head 3 and the position of the laser head 3 in the axial direction (here, the position in the Z direction) are kept constant, and then the laser head 3 is moved in the X direction. .. The support table 9 on which the mother glass plate 1 is placed is stationary, so that the mother glass plate 1 is in a stationary state. In this embodiment, the axis of the laser head 3 extends parallel to the Z direction, and the optical axis of the laser 4 also extends parallel to the Z direction.

Here, in the present embodiment, when scanning the laser 4, the laser head 3 is moved while the mother glass plate 1 is stationary, but this is not the case. On the contrary, the mother glass plate 1 may be moved while the laser head 3 is stationary. The mother glass plate 1 and the laser head 3 may be moved relative to each other. For example, when scanning the laser 4, both the mother glass plate 1 and the laser head 3 may be moved.

As the laser 4, a laser that heats the surface layer portion (surface layer portion on the upper surface 1a side) and the inside of the mother glass plate 1 is used, and a CO laser is used in this embodiment. Here, the “surface layer portion” means a region from the upper surface 1a of the mother glass plate 1 to a depth of 10 μm. On the other hand, "inside" means a region having a depth beyond the surface layer portion. The wavelength of the CO laser is, for example, 5.25 μm to 5.75 μm, and 5.5 μm in this embodiment. The laser 4 may be a pulse oscillation or a continuous oscillation.

Here, the laser 4 may be a laser other than the CO laser as long as it can heat the surface layer portion and the inside of the mother glass plate 1. For example, as the laser 4, an Er laser (Er: YAG laser), a Ho laser (Ho: YAG laser), an HF laser, or the like can be used.

The details of the irradiation conditions of the laser 4 in the laser irradiation step will be described below.

The focal point 4a of the laser 4 is located between the laser head 3 and the upper surface 1a of the mother glass plate 1. The shape of the laser spot 4b is not particularly limited and may be circular, elliptical, oval, rectangular or the like, but in the present embodiment, the laser spot 4b is irradiated so as to have a circular shape.

Here, since the mother glass plate 1 is curved, the distance between the laser head 3 and the mother glass plate 1 and the upper surface 1a of the mother glass plate 1 while the laser head 3 is moving in the X direction. The incident angle of the laser 4 with respect to the laser 4 changes continuously. As a result, the diameter of the laser spot 4b (hereinafter referred to as the irradiation diameter) also changes continuously. More specifically, the irradiation diameter becomes relatively large near the start point 6a and the end point 6b of the planned split line 6, and becomes relatively small near the midpoint 6c. The change in the size of the irradiation diameter is preferably within the range of 1 mm to 8 mm, and more preferably within the range of 2 mm to 6 mm.

In consideration of the above-mentioned change in irradiation diameter, in the present embodiment, the output of the laser 4 and the scanning speed (here, the speed at which the laser head 3 moves in the X direction) in the laser irradiation step are determined as follows. ing. In addition, the example below is a case where the size of the irradiation diameter changes within the range of 4 mm to 6 mm.

First, prepare a flat glass plate (hereinafter referred to as a flat glass plate) having the same thickness as the curved mother glass plate 1 described above. Next, when the flat glass plate is cut using the above laser 4 (laser head 3), the output capable of cutting with the size of the irradiation diameter set to 4 mm and the range of the scanning speed are determined. Further, in the same manner, the range of the output and the scanning speed at which the flat glass plate can be cut is determined by setting the size of the irradiation diameter to 6 mm. As a result, as shown in FIG. 4, the range 11 when the irradiation diameter is 4 mm and the range 12 when the irradiation diameter is 6 mm become clear. Finally, the output and scanning speed within the range 13 (the range surrounded by the thick line in FIG. 4) where both the range 11 and the range 12 overlap are determined by the output of the laser 4 in the laser irradiation step and the scanning. Determined as speed. In this embodiment, the output of the laser 4 is 38 W and the scanning speed is 20 mm / s.

Here, in order to make the thermal shock applied to the mother glass plate 1 with the irradiation of the laser 4 remarkable, the periphery of the laser spot 4b on the mother glass plate 1 may be cooled. As a specific example, the portion may be cooled by blowing a refrigerant (air or the like) toward a portion located behind the scanning direction (X direction) with reference to the laser spot 4b.

In addition to the above-mentioned irradiation conditions of the laser 4, in the present embodiment, in order to improve the properties of the cut surfaces of the first glass plate 7 and the second glass plate 8, the mother glass plate calculated by the following equation [Equation 3] The laser irradiation step is executed under the condition that the thermal stress σ _{T (MPa) of 1 satisfies the following equation [Equation 4].}

In the above equation [Equation 3], E is the Young's ratio (MPa) of the mother glass plate 1, α is the coefficient of thermal expansion (/ K) of the mother glass plate 1, ν is the Poisson's ratio of the mother glass plate 1, and ΔT is the mother. It is the difference between the temperature (K) at the irradiation position of the laser 4 with respect to the glass plate 1 and the temperature (K) at the distance position away from the irradiation position. Further, t in the above equation [Equation 4] is the thickness (mm) of the mother glass plate 1.

Here, the above-mentioned ΔT will be described in detail. At each of the irradiation position of the laser 4 and the separated position 10 mm away from the irradiation position in front of the scanning direction (X direction) of the laser 4, the mother glass plate 1 The temperature of the upper surface 1a was measured by a thermography for measuring the glass temperature (manufactured by Optris: PI450G7), and the temperature difference between the two positions was defined as ΔT. The temperature of the mother glass plate 1 during irradiation with the laser 4 can be changed by changing the conditions of the output of the laser 4 and the scanning speed. The temperature at the separated position is about the same as room temperature. Here, as described above, while the laser head 3 is moving, the distance between the laser head 3 and the mother glass plate 1 and the incident angle of the laser 4 with respect to the upper surface 1a of the mother glass plate 1 continuously change. As a result, the temperature at the irradiation position of the laser 4, and thus the above-mentioned ΔT, also changes. Therefore, in consideration of these changes, _{it is preferable that the thermal stress σ T} satisfies the condition of the above equation [Equation 4] from the start to the end of the fracture.

Under the conditions described above, the mother glass plate 1 is scanned by the laser 4 from the start point 6a to the end point 6b of the scheduled cutting line 6. At this time, at each position on the scheduled cutting line 6, a thermal shock due to the irradiation of the laser 4 is applied to the surface layer portion and the inside of the mother glass plate 1. As a result, the crack 5 grows along the planned cutting line 6 and grows along the thickness direction of the mother glass plate 1, so that the entire thickness of the mother glass plate 1 is cut.

Hereinafter, the main actions and effects of the above glass plate manufacturing method will be described.

In the above manufacturing method, a laser 4 for heating the surface layer portion and the inside of the mother glass plate 1 is used, and it is possible to apply a thermal shock not only to the surface layer portion of the mother glass plate 1 but also to the inside. Therefore, the range of irradiation conditions of the laser 4 capable of cutting the entire thickness of the mother glass plate 1 is widened. Therefore, the irradiation condition can be easily maintained at a condition that enables cutting of the entire thickness from the start to the completion of cutting the curved mother glass plate 1. As a result, the entire thickness of the mother glass plate 1 can be easily cut in the entire section of the planned cutting line 6. As a result, the properties of the cut surfaces of the first glass plate 7 and the second glass plate 8 cut out from the mother glass plate 1 can be improved.

Hereinafter, examples relating to the thermal stress σ _T of the present invention will be described.

Various mother glass plates 1 shown in the following [Table 1] were cut in the same manner as in the above embodiment. Then, in the case where a cut surface having particularly excellent properties (hereinafter referred to as a good cut surface) is obtained, the thermal stress σ _T (MPa) applied to the mother glass plate 1 is calculated by the above equation [Equation 3]. did. The quality of the cut surface was judged by visually observing.

The results of calculating the thermal stress σ _T are shown in [Table 1]. Here, as described above, the irradiation diameter and ΔT of the laser 4 change due to the curvature of the mother glass plate 1. The irradiation diameter and ΔT shown in [Table 1] are the irradiation diameter and ΔT when the laser 4 is irradiating the midpoint 6c on the scheduled cutting line 6.

As shown in the results shown in [Table 1], in order to obtain a good cut surface for the mother glass plate 1 having a thickness of about 0.5 mm, the thermal stress σ _{T at the time of cutting is about 100 MPa regardless of the type of glass.} It can be seen that it is desirable to act on the mother glass plate 1.

_{Here, it has been found that the thermal stress σ T} for obtaining a good cut surface differs depending on the thickness of the mother glass plate 1. Therefore, the inventor conducted a test of cutting a plurality of mother glass plates 1 having different thicknesses (thicknesses) with a CO laser. _{Then, the relationship between the thermal stress σ T} for obtaining a good cut surface and the thickness of the mother glass plate 1 was confirmed. In this test, non-alkali glass, soda glass, and borosilicate glass were used as the sample of the mother glass plate 1. FIG. 7 shows the relationship between the thermal stress σ _T and the thickness of the mother glass plate 1 in this test.

From the results shown in FIG. 7, the inventor of the mother glass plate 1 calculated by the above equation [Equation 3] in order to obtain a good cut surface when cutting the mother glass plate 1 with a CO laser. It has been found that it is desirable to carry out the laser irradiation step so that the thermal stress σ _{T (MPa) satisfies the above equation [Equation 4].}

Here, the method for manufacturing a glass plate according to the present invention is not limited to the embodiment described in the above embodiment.

For example, in the above embodiment, when scanning the laser 4, the inclination of the axis of the laser head 3 and the position of the laser head 3 in the axial direction are fixed, but this is not the case. When the height difference H generated on the upper surface 1a of the mother glass plate 1 along the planned cutting line 6 is large (for example, when the height difference H exceeds 20 mm), the form as shown in FIGS. 5 and 6 is adopted. It may be adopted.

In the form shown in FIG. 5, the inclination of the axis of the laser head 3 is changed according to the curvature of the mother glass plate 1. More specifically, the inclination of the axis of the laser head 3 is changed for the purpose of reducing the incident angle of the laser 4 with respect to the upper surface 1a of the mother glass plate 1. In this case, the distance between the laser head 3 and the mother glass plate 1 and the angle of incidence of the laser 4 with respect to the upper surface 1a of the mother glass plate 1 are constant. The upper limit of the incident angle is preferably 45 °. Further, in the form shown in the figure, in addition to changing the inclination of the axis of the laser head 3, the height position of the laser head 3 is also changed. That is, when scanning the vicinity of the start point 6a and the end point 6b of the scheduled cutting line 6 with the laser 4, the height position of the laser head 3 is relatively lowered, and the vicinity of the midpoint 6c of the scheduled cutting line 6 is scanned. In some cases, the height position of the laser head 3 is relatively high.

In the embodiment shown in FIG. 6, while the inclination of the axis of the laser head 3 is made constant, the position of the laser head 3 in the axial direction (here, the position in the Z direction) is changed according to the curvature of the mother glass plate 1. I'm letting you. More specifically, the height position of the laser head 3 is set relatively low when scanning the vicinity of the start point 6a and the end point 6b of the scheduled cut line 6 with the laser 4, and the vicinity of the midpoint 6c of the scheduled cut line 6 is set. Is relatively high when scanning. In this case, the distance between the laser head 3 and the mother glass plate 1 is constant, but the incident angle of the laser 4 with respect to the upper surface 1a of the mother glass plate 1 changes continuously.

Of course, when scanning the laser 4, a form may be adopted in which both the inclination of the axis of the laser head 3 and the position of the laser head 3 in the axial direction are changed. For example, a mode may be adopted in which the distance between the laser head 3 and the mother glass plate 1 is continuously changed so that the incident angle of the laser 4 with respect to the upper surface 1a of the mother glass plate 1 is constant. Such a form and the form shown in FIGS. 5 and 6 can be realized by using a robot (a combination of an articulated robot, a single-axis robot, etc.), a linear actuator, a rotation mechanism, and the like.

Further, in the above embodiment, the mother glass plate 1 is cut with the convex surface of the curved mother glass plate 1 as the upper surface 1a, but this is not the case. The mother glass plate 1 may be cut by inverting the front and back sides of the mother glass plate 1 so that the concave surface is the upper surface 1a. In this case, the surface forming the initial crack 2 may be the upper surface 1a (concave surface), the lower surface 1b (convex surface), or the end surface. Further, in the above embodiment, the mother glass plate 1 in the flat position is cut, but this is not the case. The mother glass plate 1 in a vertical posture or an inclined posture may be cut by a holding member or the like.

Further, in the above embodiment, the planned division line 6 extends in the X direction in a plan view, but this is not the case. The planned split line 6 may be a meandering line or a line forming a closed loop (for example, a line drawing a circle in a plan view).

Further, in the above embodiment, the mother glass plate 1 curved along the two directions of the X direction and the Y direction is targeted for cutting, but this is not the case. The present invention can also be applied to the case of cutting the mother glass plate 1 which is curved only in one direction.

1 Mother glass plate 1a Top surface of mother glass plate 2 Initial crack 3 Laser head 4 Laser 5 Crack 6 Split scheduled line

Claims

An initial crack forming step of forming an initial crack that is a starting point of cutting on a curved mother glass plate, and
A method for manufacturing a glass plate, comprising a laser irradiation step of irradiating the mother glass plate with a laser from a laser head to advance the cracks along a planned cutting line starting from the initial cracks.
In the laser irradiation step, the laser that heats the surface layer portion and the inside of the mother glass plate is used to develop the crack along the planned cutting line by the thermal shock accompanying the irradiation of the laser, and the mother glass. A method for producing a glass plate, which comprises cutting the mother glass plate by extending the plate along the thickness direction of the plate.
The method for manufacturing a glass plate according to claim 1, wherein in the laser irradiation step, the inclination of the axis of the laser head is kept constant and then the laser head and the mother glass plate are relatively moved.
The glass plate according to claim 1 or 2, wherein in the laser irradiation step, the position of the laser head in the axial direction is fixed, and then the laser head and the mother glass plate are relatively moved. Manufacturing method.
The method for manufacturing a glass plate according to any one of claims 1 to 3, wherein a CO laser is used as the laser in the laser irradiation step.
The laser irradiation step is executed under the condition that the thermal stress σ T (MPa) of the mother glass plate calculated by the following equation [Equation 1] satisfies the following equation [Equation 2]. The method for manufacturing a glass plate according to any one of claims 1 to 4.

However, E is the Young's modulus (MPa) of the mother glass plate, α is the coefficient of thermal expansion (/ K) of the mother glass plate, ν is the Poisson's ratio of the mother glass plate, and ΔT is the laser with respect to the mother glass plate. It is the difference between the temperature (K) at the irradiation position and the temperature (K) at the distance position away from the irradiation position.

However, t is the thickness (mm) of the mother glass plate.
The laser irradiation step is characterized in that at least one of (1) the distance between the laser head and the mother glass plate and (2) the angle of incidence of the laser on the surface of the mother glass plate is changed. The method for manufacturing a glass plate according to any one of claims 1 to 5.