TWI886205B - Method for manufacturing glass plate - Google Patents

Abstract

The manufacturing method of the glass plate of the present invention comprises: an initial crack forming step, in which an initial crack 2 serving as a starting point for cutting is formed on a bent plain glass plate 1; and a laser irradiation step, in which a laser 4 is irradiated from a laser head 3 to the plain glass plate 1, so that a crack 5 is extended along a predetermined cutting line 6 starting from the initial crack 2; in the laser irradiation step, a laser 4 is used to heat the surface and the inside of the plain glass plate 1, and the crack 5 is extended along the predetermined cutting line 6 and in the thickness direction of the plain glass plate 1 by utilizing the thermal shock accompanying the irradiation of the laser 4, so that the plain glass plate 1 is cut.

Description

Method for manufacturing glass plate

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

As a protective glass for smartphone displays or car displays, a three-dimensional (3D) glass plate that is curved vertically and horizontally is sometimes used. When manufacturing such a glass plate, for example, a curved mother glass plate (a glass plate having a 3D shape with multiple surface portions) that is a raw material of the glass plate is cut out and manufactured.

Here, as one of the techniques 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 predetermined cutting line, first, an initial crack is formed on the glass plate using a diamond cutter or the like, which serves as the starting point for cutting. Then, a carbon dioxide laser is irradiated from a laser head onto the glass plate, and a coolant (air, etc.) is sprayed toward the portion heated by the laser irradiation. At this time, the glass plate is cut by utilizing the thermal shock applied to the glass plate to extend the crack along the predetermined cutting line starting from the initial crack. [Prior art literature] [Patent literature]

Patent document 1: Japanese Patent Publication No. 2011-116611

[Problems to be Solved by the Invention] However, when cutting the curved plain glass plate, when using the laser cutting method described above, the following problems to be solved arise.

That is, when a plain glass plate is irradiated with a carbon dioxide laser, only the surface layer of the plain glass plate (the surface layer on the laser incident surface) is heated by the laser. In the case of a carbon dioxide laser that can only heat the surface layer, the range of irradiation conditions that can cut the entire thickness of the plain glass plate is extremely narrow. For example, if the distance between the laser head and the plain glass plate is slightly deviated from the optimal distance, the thermal shock is insufficient and it is difficult to cut. Therefore, it is very difficult to maintain the laser irradiation conditions that can cut the entire thickness of the curved plain glass plate from the beginning to the end of cutting. As a result of the difficulty in cutting the entire thickness, the plain glass plate needs to be separately broken in order to cut it, and there is a problem that the properties of the cross-section of the glass plate cut out from the plain glass plate are easily deteriorated.

The technical subject of the present invention completed in view of the above situation is to improve the properties of the cut surface of a glass plate cut out from a bent plain glass plate when the plain glass plate is cut by laser cutting.

[Means for Solving the Problem] In order to solve the above-mentioned problem, the manufacturing method of the glass plate of the present invention comprises: an initial crack forming step, forming an initial crack as a starting point for cutting in a bent plain glass plate; and a laser irradiation step, irradiating the plain glass plate with laser from a laser head, so that the crack is extended along a predetermined cutting line starting from the initial crack; and the characteristic of the method is that: in the laser irradiation step, a laser is used to heat the surface and the inside of the plain glass plate, and the crack is extended along the predetermined cutting line and in the thickness direction of the plain glass plate by utilizing the thermal shock accompanying the irradiation of the laser, so as to cut the plain glass plate.

In this method, in the laser irradiation step, a laser that heats the surface and the inside of the plain glass plate is used. In such a laser that can heat not only the surface but also the inside, it is possible to apply a heat shock not only to the surface but also to the inside, so the range of laser irradiation conditions that can cut the entire thickness of the plain glass plate is wide. Thereby, during the period from the beginning to the end of cutting the bent plain glass plate, it is easy to maintain the laser irradiation conditions to conditions that can cut the entire thickness. Therefore, the entire thickness of the plain glass plate can be easily cut within the entire area of the predetermined cutting line. As a result, the properties of the cut surface of the glass plate cut from the plain glass plate can be improved.

In the method, it is preferred that in the laser irradiation step, after the inclination of the axis of the laser head is fixed, the laser head and the plain glass plate are moved relative to each other.

As described above, in the laser that heats the surface and the inside of the plain glass plate, the range of irradiation conditions that can cut the entire thickness of the plain glass plate is wide. Therefore, when cutting the plain glass plate, when the laser head and the plain glass plate are moved relative to each other and the curved plain glass plate is scanned by the laser, the entire thickness can be cut even without changing the inclination of the axis of the laser head according to the bending. Therefore, it is only necessary to set the inclination of the axis to be fixed, and there is no need to set a mechanism for changing the inclination of the axis of the laser head, thereby reducing equipment costs. In addition, since there is no need to change the inclination of the axis, the time required to cut the plain glass plate can be shortened.

In the method, it is preferred that in the laser irradiation step, after the position of the laser head in its axial direction is fixed, the laser head and the plain glass plate are moved relative to each other.

In the laser, as described above, the range of irradiation conditions that can cut the entire thickness of the plain glass plate is wide. Thus, when cutting the plain glass plate, even if the position of the laser head in the axial direction is not changed according to the bending of the plain glass plate, the entire thickness can be cut. Therefore, it is only necessary to set the position in the axial direction to be fixed, and there is no need to set a mechanism for changing the position in the axial direction, so that the equipment cost can be further reduced. In addition, since there is no need to change the position in the axial direction, the time required for cutting the plain glass plate can be further shortened.

In the method, it is preferred that a carbon monoxide (CO) laser is used as the laser in the laser irradiation step.

With this arrangement, the CO laser has high output and can be stably irradiated to the plain glass plate, so the crack can be stably extended along the predetermined cutting line.

In the above method, it is preferred that the laser irradiation step is performed under the condition that the thermal stress σ _T (MPa) of the plain glass plate calculated by the following [Formula 1] satisfies the following [Formula 2]. [Formula 1] Where E is the Young's modulus (MPa) of the plain glass plate, α is the thermal expansion coefficient (/K) of the plain glass plate, ν is the Poisson's ratio of the plain glass plate, and ΔT is the difference between the temperature (K) at the laser irradiation position on the plain glass plate and the temperature (K) at a distance away from the irradiation position. [Formula 2] Where t is the thickness of the plain glass sheet (mm).

By configuring in this way, the properties of the cross-section of the glass plate cut out from the plain glass plate can be further improved.

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

In the laser irradiation, since the range of irradiation conditions that can cut the entire thickness of the plain glass plate is wide, even if one or both of the above-mentioned (1) and (2) are changed, the entire thickness can still be cut. In other words, it is not necessary to strictly perform the above-mentioned (1) or (2) management during the laser irradiation step in order to cut the entire thickness.

[Effect of the invention] According to the present invention, when a curved plain glass plate is cut by laser cutting, the properties of the cut surface of the glass plate cut from the plain glass plate can be improved.

Hereinafter, the manufacturing method of the glass plate of the embodiment of the present invention will be described with reference to the attached drawings. In addition, the X direction, Y direction, and Z direction shown in the drawings referred to in the description of the embodiment are mutually orthogonal directions. Moreover, the X direction and the Y direction are horizontal directions, and the Z direction is the vertical direction.

The manufacturing method of the glass plate in the embodiment includes: an initial crack forming step (Figure 1), which is used to form an initial crack 2 that becomes the starting point of cutting on the bent plain glass plate 1; and a laser irradiation step (Figures 2 and 3), which is used to irradiate the plain glass plate 1 with a laser 4 from a laser head 3, so that a crack 5 is extended along a predetermined cutting line 6 with the initial crack 2 as the starting point.

In the present embodiment, the plain glass plate 1 is cut along a predetermined cutting line 6 to be divided into a first glass plate 7 and a second glass plate 8. The predetermined cutting line 6 is located at the center of the plain glass plate 1 in the Y direction, and the plain glass plate 1 is formed into a shape symmetrical with respect to the predetermined cutting line 6. One end of the predetermined cutting line 6 serves as a starting point 6a for starting the cutting of the plain glass plate 1, and the other end serves as an end point 6b for finishing the cutting.

As shown in FIG1 , the plain glass plate 1 has a 3D shape that is curved in either the X direction or the Y direction, and the upper surface 1a is convex among the upper surface 1a and the lower surface 1b. The plain glass plate 1 is rectangular in shape when viewed from above (viewed from the Z direction). In this embodiment, when viewed from above, the predetermined cutting line 6 extends in the X direction. Due to the curvature of the glass plate 1, a height difference H (difference in height along the Z direction) is generated on the upper surface 1a along the predetermined cutting line 6. In detail, the height of the upper surface 1a is the lowest at the starting point 6a and the end point 6b of the predetermined cutting line 6, and the height of the upper surface 1a is the highest at the midpoint 6c of the predetermined cutting line 6. The height difference H is, for example, less than 20 mm, and preferably less than 10 mm. In this embodiment, the height difference H is 10 mm.

The thickness of the plain glass plate 1 is, for example, 0.05 mm to 5 mm. Furthermore, as will be described in detail later, in this embodiment, a CO laser is used as the laser 4 irradiated to the plain glass plate 1, and a thicker plain glass plate 1 can be cut compared to the case of using a carbon dioxide laser. Therefore, the thickness of the plain glass plate 1 is preferably greater than 0.1 mm, more preferably greater than 0.2 mm, and further preferably greater than 0.3 mm. On the other hand, the thickness of the plain glass plate 1 is preferably less than 3 mm. In this embodiment, the thickness of the plain glass plate 1 is 0.7 mm.

The plain glass plate 1 may be silicate glass, silica glass, borosilicate glass, soda glass, soda lime glass, aluminosilicate glass, alkali-free glass, etc. Here, the so-called "alkali-free glass" refers to glass that does not substantially contain alkali components (alkali metal oxides), and specifically, refers to glass in which the weight ratio of alkali components is 3000 ppm or less. The weight ratio of alkali components is preferably 1000 ppm or less, more preferably 500 ppm or less, and most preferably 300 ppm or less. Furthermore, the plain 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 subjected to chemical strengthening treatment.

In the initial crack forming step shown in Fig. 1, first, a plain glass plate 1 is placed in a flat position on a support table 9 having a flat support surface 9a. Then, an initial crack 2 is formed on the placed plain glass plate 1 at a location where a starting point 6a of a predetermined cutting line 6 is located on the upper surface 1a thereof.

When the initial crack 2 is formed, a crack forming member 10 is used. In the present embodiment, a pointed scriber (sintered diamond cutter, etc.) is used as the crack forming member 10. Of course, the present invention is not limited thereto, and a diamond pen, a superhard alloy cutter, sand paper, etc. may also be used as the crack forming member 10. The initial crack 2 is formed by lowering the crack forming member 10 from above and contacting the upper surface 1a of the plain glass plate 1.

Here, in this embodiment, the initial crack 2 is formed on the upper surface 1a (convex surface) of the upper surface 1a and the lower surface 1b of the plain glass plate 1, but the present invention is not limited thereto, and the initial crack 2 may be formed on the lower surface 1b (concave surface). In addition, the initial crack 2 may be formed on the end surface of the plain glass plate 1.

In the laser irradiation step shown in FIGS. 2 and 3 , the laser 4 is irradiated to the initial crack 2 located at the starting point 6 a of the predetermined cutting line 6 , and from this state, the plain glass plate 1 is scanned along the predetermined cutting line 6 by the laser 4 .

During scanning by the laser 4, after the inclination of the axis of the laser head 3 and the position of the laser head 3 in the axis direction (here, the position in the Z direction) are fixed, the laser head 3 is moved in the X direction. Furthermore, the support table 9 on which the plain glass plate 1 is placed is stationary, whereby the plain 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, during the scanning of the laser 4, the laser head 3 is moved while the plain glass plate 1 is stationary, but the present invention is not limited thereto. Conversely, the plain glass plate 1 may be moved while the laser head 3 is stationary. Furthermore, it is sufficient that the plain glass plate 1 and the laser head 3 are relatively moved. For example, during the scanning of the laser 4, both the plain glass plate 1 and the laser head 3 may be moved.

As the laser 4, a laser that heats the surface layer (the surface layer on the upper surface 1a side) and the interior of the plain glass plate 1 is used. In this embodiment, a CO laser is used. Here, the so-called "surface layer" refers to the area from the upper surface 1a of the plain glass plate 1 to a depth of 10 μm. In contrast, the so-called "interior" refers to an area deeper than the surface layer. The wavelength of the CO laser is 5.25 μm to 5.75 μm as an example, and is 5.5 μm in this embodiment. The laser 4 can be a pulse oscillation or a continuous oscillation.

Here, the laser 4 may be a laser other than a CO laser if it can heat the surface and the inside of the plain glass plate 1. For example, as the laser 4, an Er laser (Er: yttrium aluminum garnet (YAG) laser), a Ho laser (Ho: YAG laser), or a HF (hydrogen fluoride) laser may be used.

The following describes in detail the irradiation conditions of the laser 4 in the laser irradiation step.

The focus 4a of the laser 4 is positioned between the laser head 3 and the upper surface 1a of the plain glass plate 1. The shape of the laser spot 4b is not particularly limited and may be circular, elliptical, oblong, rectangular, etc. In this embodiment, the laser spot 4b is irradiated in a circular shape.

Here, since the plain glass plate 1 is curved, the distance between the laser head 3 and the plain glass plate 1 and the incident angle of the laser 4 on the upper surface 1a of the plain glass plate 1 continuously change during the movement of the laser head 3 in the X direction. As a result, the diameter of the laser spot 4b (hereinafter referred to as the irradiation diameter) also changes continuously. Specifically, the irradiation diameter becomes relatively larger near the starting point 6a and the end point 6b of the predetermined cutting line 6, and becomes relatively smaller near the midpoint 6c. The change in the size of the irradiation diameter preferably falls within the range of 1 mm to 8 mm, and more preferably falls within the range of 2 mm to 6 mm.

Taking into account the change in the irradiation diameter, in this embodiment, the output of the laser 4 in the laser irradiation step and the scanning speed (here, the speed at which the laser head 3 moves in the X direction) are determined as follows. In addition, the following example shows the case where the irradiation diameter varies within the range of 4 mm to 6 mm.

First, a glass plate (hereinafter referred to as a flat glass plate) is prepared, which has the same thickness as the bent plain glass plate 1 and is formed flat. Next, when the flat glass plate is cut using the laser 4 (laser head 3), the output that can be cut and the range of the scanning speed are calculated by setting the size of the irradiation diameter to 4 mm. Furthermore, similarly, the output that can cut the flat glass plate and the range of the scanning speed are calculated by setting the size of the irradiation diameter to 6 mm. Thereby, as shown in FIG. 4, the range 11 when the irradiation diameter is set to 4 mm and the range 12 when the irradiation diameter is set to 6 mm are clearly determined. Finally, the output and scanning speed within the range 13 (the range surrounded by the thick line in FIG. 4 ) where the range 11 and the range 12 overlap are determined as the output and scanning speed of the laser 4 in the laser irradiation step. In this embodiment, the output of the laser 4 is set to 38 W and the scanning speed is set to 20 mm/s.

Here, in order to make the thermal shock applied to the plain glass plate 1 accompanying the irradiation of the laser 4 significant, the periphery of the laser spot 4b in the plain glass plate 1 may be cooled. As a specific example, a cooling medium (air, etc.) may be blown toward a portion located behind the laser spot 4b in the scanning direction (X direction), thereby cooling the portion.

In this embodiment, in addition to the above-mentioned laser irradiation conditions, in order to improve the properties of the cross-section of the first glass plate 7 and the second glass plate 8, the laser irradiation step is performed under the condition that the thermal stress σ _T (MPa) of the plain glass plate 1 calculated by the following [Formula 3] satisfies the following [Formula 4]. [Formula 3] [Formula 4]

In the above [Formula 3], E is the Young's modulus (MPa) of the plain glass plate 1, α is the thermal expansion coefficient (/K) of the plain glass plate 1, ν is the Passon's ratio of the plain glass plate 1, and ΔT is the difference between the temperature (K) at the irradiation position of the laser 4 on the plain glass plate 1 and the temperature (K) at a position away from the irradiation position. In addition, in the above [Formula 4], t is the thickness (mm) of the plain glass plate 1.

Here, the ΔT is described in detail. The temperature of the upper surface 1a of the plain glass plate 1 is measured using a glass temperature measurement thermograph (PI450G7 manufactured by Optris) at the irradiation position of the laser 4 and at a position 10 mm away from the irradiation position in the scanning direction (X direction) of the laser 4, and the temperature difference between the two positions is set as ΔT. The temperature of the plain glass plate 1 during the irradiation of the laser 4 can be changed by changing the output or scanning speed of the laser 4 described above. In addition, the temperature of the separated position is about the same as the room temperature. Here, during the movement of the laser head 3 as described above, the distance between the laser head 3 and the plain glass plate 1 and the incident angle of the laser 4 on the upper surface 1a of the plain glass plate 1 continuously change. As a result, the temperature at the irradiation position of the laser 4 changes, and further, the ΔT also changes. Therefore, considering these changes, it is preferable that the thermal stress σ _T satisfies the condition of the above [Formula 4] during the period from the start to the end of the cutting.

Under the conditions described above, the plain glass plate 1 is scanned from the starting point 6a to the end point 6b of the predetermined cutting line 6 by the laser 4. At this time, at each position on the predetermined cutting line 6, the thermal shock accompanying the irradiation of the laser 4 is applied to the surface and the inside of the plain glass plate 1. Thereby, the crack 5 expands along the predetermined cutting line 6 and expands along the thickness direction of the plain glass plate 1, and the entire thickness of the plain glass plate 1 is cut.

Hereinafter, main functions and effects achieved by the method for manufacturing the glass sheet will be described.

In the manufacturing method, a laser 4 that heats the surface and the inside of the plain glass plate 1 is used, so that heat shock can be applied not only to the surface but also to the inside of the plain glass plate 1. Therefore, the range of irradiation conditions of the laser 4 that can cut the entire thickness of the plain glass plate 1 is widened. Therefore, during the period from the start of cutting to the end of the bent plain glass plate 1, the irradiation conditions can be easily maintained as conditions that can cut the entire thickness. Thereby, the entire thickness of the plain glass plate 1 can be easily cut within the entire area of the predetermined 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 from the plain glass plate 1 can be improved. [Example]

Hereinafter, an embodiment of the thermal stress σ _T of the present invention will be described.

In the same manner as in the above-mentioned embodiment, various plain glass plates 1 shown in the following [Table 1] were cut. Then, when a cut surface with particularly excellent properties (hereinafter referred to as a good cut surface) was obtained, the thermal stress σ _T (MPa) acting on the plain glass plate 1 was calculated by the above-mentioned [Formula 3]. Furthermore, the quality of the cut surface was determined by visual observation.

The results of calculating the thermal stress σ _T are shown in [Table 1]. Here, as mentioned above, the irradiation diameter and ΔT of the laser 4 change due to the bending of the glass plate 1. The irradiation diameter and ΔT shown in [Table 1] are the irradiation diameter and ΔT when the laser 4 irradiates to the midpoint 6c on the predetermined cutting line 6. [Table 1] Glass Category Alkaline-free Alkaline-free Borosilicate Sodium Sodium Young's modulus (GPa) 73 80 77 73 70 Thermal expansion coefficient (×10 ^-7 /K) 38 45 66 90 91 Pasombi 0.2 0.2 0.2 0.2 0.2 Thickness (mm) 0.5 0.5 0.5 0.5 0.55 Output (W) 38 38 38 38 38 Speed (mm/sec) 20 40 70 90 90 Irradiation diameter (mm) 6 6 6 6 6 ΔT (K) 550 420 320 250 260 _σT (MPa) 95 95 102 103 104

As shown in the results in [Table 1], it can be seen that for a plain glass plate 1 with a thickness of about 0.5 mm, in order to obtain a good cross-section, it is ideal to apply a thermal stress σ _T of about 100 MPa to the plain glass plate 1 during cutting regardless of the type of glass.

Here, it is clear that the thermal stress σ _T for obtaining a good cross section varies depending on the thickness of the plain glass plate 1. Therefore, the inventor conducted an experiment in which a plurality of plain glass plates 1 with different thicknesses (wall thicknesses) were cut by CO laser. Then, the relationship between the thermal stress σ _T for obtaining a good cross section and the thickness of the plain glass plate 1 was confirmed. In this experiment, alkali-free glass, sodium glass, and borosilicate glass were used as samples of the plain glass plate 1. The relationship between the thermal stress σ _T and the thickness of the plain glass plate 1 in this experiment is shown in FIG7 .

According to the results shown in FIG. 7 , the inventors found that when cutting the plain glass plate 1 using a CO laser, in order to obtain a good cross-section, it is ideal to perform the laser irradiation step in such a way that the thermal stress σ _T (MPa) of the plain glass plate 1 calculated by the above [Formula 3] satisfies the above [Formula 4].

Here, the method for manufacturing the glass plate of the present invention is not limited to the form described in the above-mentioned embodiment.

For example, in the above-described embodiment, during the scanning of 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 the present invention is not limited thereto. When the height difference H generated on the upper surface 1a of the plain glass plate 1 along the predetermined cutting line 6 is large (for example, when the height difference H exceeds 20 mm), the configuration shown in FIG. 5 or FIG. 6 may also be adopted.

In the form shown in FIG. 5 , the inclination of the axis of the laser head 3 is changed according to the bending of the plain glass plate 1. 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 on the upper surface 1a of the plain glass plate 1. In this case, the mutual distance between the laser head 3 and the plain glass plate 1 and the incident angle of the laser 4 on the upper surface 1a of the plain glass plate 1 are fixed. Furthermore, it is preferable to set the upper limit value of the incident angle to 45°. Furthermore, in the form shown in the same 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 the laser 4 is used to scan the vicinity of the starting point 6a and the end point 6b of the predetermined cutting line 6, the height position of the laser head 3 is relatively lowered, and when the laser 4 is used to scan the vicinity of the midpoint 6c of the predetermined cutting line 6, the height position of the laser head 3 is relatively raised.

In the form shown in FIG6 , the inclination of the axis of the laser head 3 is fixed, and on the other hand, the position of the laser head 3 in the axis direction (here, the position in the Z direction) is changed according to the curvature of the plain glass plate 1. Specifically, the height position of the laser head 3 is relatively lowered when the laser 4 is used to scan the vicinity of the starting point 6a and the end point 6b of the predetermined cutting line 6, and is relatively raised when the laser 4 is used to scan the vicinity of the midpoint 6c of the predetermined cutting line 6. In this case, although the distance between the laser head 3 and the plain glass plate 1 is fixed, the incident angle of the laser 4 on the upper surface 1a of the plain glass plate 1 continuously changes.

Of course, during the scanning of the laser 4, a configuration can 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, the following configuration can be adopted: the distance between the laser head 3 and the plain glass plate 1 is continuously changed, and the incident angle of the laser 4 to the upper surface 1a of the plain glass plate 1 is fixed. This configuration and the configuration shown in FIG. 5 or FIG. 6 can be realized using a robot (a combination of a multi-joint robot, a single-axis robot, etc.), a linear actuator (actuator), a rotary mechanism, etc.

Furthermore, in the above-described embodiment, the plain glass plate 1 is cut after the convex surface of the bent plain glass plate 1 is made the upper surface 1a, but the present invention is not limited to this. The plain glass plate 1 may be cut after the front and back sides are reversed and the concave surface is made the upper surface 1a. In this case, the surface on which the initial crack 2 is formed may be the upper surface 1a (concave surface), the lower surface 1b (convex surface), or the end surface. Furthermore, in the above-described embodiment, the plain glass plate 1 is cut after being set in a horizontal position, but the present invention is not limited to this. The plain glass plate 1 may be cut after being set in a vertical position or a tilted position by a retaining member or the like.

In the above-described embodiment, the predetermined cutting line 6 extends in the X direction when viewed from above, but the present invention is not limited thereto. The predetermined cutting line 6 may be a zigzag line or a line that forms a closed loop (for example, a line that draws a circle when viewed from above).

In the above-described embodiment, the plain glass plate 1 curved in both directions of the X direction and the Y direction is cut, but the present invention is not limited thereto. The present invention can also be applied to the case where the plain glass plate 1 curved in only one direction is cut.

1: Plain glass plate 1a: Upper surface of plain glass plate 1b: Lower surface of plain glass plate 2: Initial crack 3: Laser head 4: Laser 4a: Focus of laser 4b: Laser point 5: Crack 6: Predetermined cutting line 6a: Starting point 6b: End point 6c: Midpoint 7: First glass plate 8: Second glass plate 9: Support table 9a: Support surface of support table 10: Crack forming member 11, 12, 13: Range H: Height difference X, Y, Z: Direction

FIG. 1 is a perspective view showing an initial crack formation step in a method for manufacturing a glass plate. FIG. 2 is a perspective view showing a laser irradiation step in a method for manufacturing a glass plate. FIG. 3 is a cross-sectional view showing a laser irradiation step in a method for manufacturing a glass plate. FIG. 4 is a diagram showing irradiation conditions of the laser in the laser irradiation step. FIG. 5 is a cross-sectional view showing a laser irradiation step in a method for manufacturing a glass plate. FIG. 6 is a cross-sectional view showing a laser irradiation step in a method for manufacturing a glass plate. FIG. 7 is a diagram showing the relationship between thermal stress and the thickness of a plain glass plate.

1: Plain glass plate

1a: Upper surface of plain glass plate

1b: Bottom surface of plain glass plate

2: Initial cracks

3: Laser head

4: Laser

4a: Focus of laser

4b: Laser point

5: Cracks

6: Predetermined cutting line

6a: Starting point

6b: End point

6c: Midpoint

7: First glass plate

8: Second glass plate

9: Support Desk

9a: Support surface

X, Y, Z: direction

Claims (5)

A method for manufacturing a glass plate comprises: an initial crack forming step, forming an initial crack as a starting point for cutting on a bent plain glass plate; and a laser irradiation step, irradiating the plain glass plate with laser from a laser head, thereby extending the crack along a predetermined cutting line starting from the initial crack; and the manufacturing method of the glass plate is characterized in that: in the laser irradiation step, the laser is used to heat the surface and the inside of the plain glass plate, and the crack is extended along the predetermined cutting line and along the thickness direction of the plain glass plate by utilizing the thermal shock accompanying the irradiation of the laser, thereby cutting the plain glass plate, In the laser irradiation step, after the inclination of the axis of the laser head is set to be fixed, the laser head and the plain glass plate are moved relative to each other. The method for manufacturing a glass plate as described in claim 1, wherein in the laser irradiation step, after the position of the laser head in its axial direction is fixed, the laser head and the plain glass plate are moved relative to each other. The method for manufacturing a glass plate as described in claim 1 or claim 2, wherein in the laser irradiation step, a carbon monoxide laser is used as the laser. The method for manufacturing a glass plate according to claim 1 or claim 2, wherein the laser irradiation step is performed under the condition that the thermal stress σ _T (MPa) of the plain glass plate calculated by the following [Formula 1] satisfies the following [Formula 2], [Formula 1] Wherein, E is the Young's modulus (MPa) of the plain glass plate, α is the thermal expansion coefficient (/K) of the plain glass plate, ν is the Passon's ratio of the plain glass plate, ΔT is the difference between the temperature (K) at the position where the laser irradiates the plain glass plate and the temperature (K) at a position away from the irradiation position, [Formula 2] Here, t is the thickness of the plain glass plate (mm). A method for manufacturing a glass plate as described in claim 1 or claim 2, wherein in the laser irradiation step, at least one of (1) the distance between the laser head and the plain glass plate, and (2) the incident angle of the laser on the surface of the plain glass plate is changed.