Glass plate processing method

Abstract

A large plate has a first main surface and a second main surface, and is separated into a first small plate and a second small plate at a separation surface. The separation surface has a curve section at each of a first intersection line intersecting with the first main surface, and a second intersection line intersecting with the second main surface. In plan view, the first intersection line is positioned on one side of the second intersection line. In a cross section orthogonal to the first intersection line, the separation surface is inclined relative to a line normal to the first main surface. (1) Laser light is collected inside the large plate, and a modified section is formed on the separation surface at which separation is to occur. (2) After formation of the modified section, stress is applied to the large plate to form a crack in the separation surface. (3) After formation of the crack, the first small plate and the second small plate are offset in the direction of the line normal to the first main surface, and the first small plate and the second small plate are separated.

Description

[Technical Field]

[0001] The present disclosure relates to a method for processing a glass sheet, and a glass sheet. [Background technology]

[0002] In Patent Document 1, a large glass plate is irradiated with laser light to form numerous microcracks inside the large plate. The numerous microcracks are formed on a separation surface where the large plate will be separated into a first small plate and a second small plate. Stress is then applied to the glass plate to form cracks on the separation surface, allowing the large plate to be separated into the first small plate and the second small plate at the separation surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-64916 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, when a large plate is separated into a first small plate and a frame-shaped second small plate surrounding the first small plate, the second small plate is further crushed into a large number of pieces to obtain the first small plate.

[0005] One aspect of the present disclosure provides a technique that allows separation of a large platelet into a first small platelet and a second small platelet without crushing either the first small platelet or the second small platelet. [Means for solving the problem]

[0006] A glass plate processing method according to one embodiment of the present disclosure separates a large glass plate having a first main surface and a second main surface facing opposite to the first main surface into a first small glass plate and a second small glass plate at a separation surface. The separation surface has a curved portion on each of a first intersection line intersecting with the first main surface and a second intersection line intersecting with the second main surface. In a plan view, the first intersection line is located on one side of the second intersection line. In a cross section perpendicular to the first intersection line, the separation surface teeth is inclined with respect to the normal to the first main surface, The angle between the separation surface and the normal to the first main surface is 3° or more and 45° or less. The processing method includes the following steps (1) to (3): (1) forming a metal layer inside the large plate; The first pulsed light The laser light is focused, by nonlinear absorption (2) forming a modified portion on the separation surface to be separated; The large plate is irradiated with the second laser beam to mainly cause linear absorption, and the large plate is heated so that the temperature of the large plate becomes equal to or lower than the annealing point. Stress is applied to form cracks in the separation surface. When the propagation distance of the second laser light from the first main surface to the second main surface is L and the absorption coefficient of the glass with respect to the second laser light is α, α×L is 0.002 or more and 3.0 or less. (3) After the crack is formed, the first small plate and the second small plate are shifted in the normal direction of the first main surface to separate the first small plate and the second small plate. [Effects of the Invention]

[0007] According to one aspect of the present disclosure, when a large platelet is separated into a first small platelet and a second small platelet, the separation can be performed without crushing either the first small platelet or the second small platelet. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a flowchart showing a method for processing a glass plate according to the first embodiment. [Figure 2A] FIG. 2A is a plan view showing S1 in FIG. [Figure 2B] FIG. 2B is a cross-sectional view showing S1 in FIG. 1, taken along line IIB-IIB in FIG. 2A. [Figure 3] FIG. 3 is a cross-sectional view showing S2 in FIG. [Figure 4] FIG. 4 is a cross-sectional view showing S3 in FIG. [Figure 5] FIG. 5 is a cross-sectional view showing S4 in FIG. [Figure 6] FIG. 6 is a cross-sectional view showing S5 in FIG. [Figure 7] FIG. 7 is a flowchart showing a method for processing a glass plate according to the second embodiment. [Figure 8] FIG. 8 is a cross-sectional view showing S6 in FIG. [Figure 9] FIG. 9 is a plan view showing the separation surface of the glass plate according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and their description may be omitted. In the specification, the symbol "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0010] (First embodiment) As shown in Fig. 1, the method for processing a glass plate includes steps S1 to S5. S1 to S5 in Fig. 1 will be described below with reference to Figs. 2A, 2B, and 3 to 6.

[0011] First, in S1 of FIG. 1, a large plate 10 is prepared as shown in FIGS. 2A and 2B. The large plate 10 is a glass plate. The large plate 10 may be a bent plate, but in this embodiment, it is a flat plate. The large plate 10 has a first main surface 11 and a second main surface 12 facing opposite to the first main surface 11. If the large plate 10 is a bent plate, it may have a single curved shape curved in a single direction, or a complex curved shape curved in both the longitudinal and lateral directions. If the large plate 10 has a single curved shape, the radius of curvature of the large plate 10 is preferably 5,000 mm or more and 100,000 mm or less. If the large plate 10 has a complex curved shape, the radius of curvature of the large plate 10 is preferably 1,000 mm or more and 100,000 mm or less. The large plate 10 is bent by softening the glass by heating it to 550°C to 700°C. The large plate 10 can be bent by gravity forming, press forming, roller forming, vacuum forming, or the like.

[0012] The shape of the first main surface 11 and the second main surface 12 is, for example, rectangular. Note that the shape of the first main surface 11 and the second main surface 12 may be trapezoidal, circular, elliptical, or the like, and is not particularly limited.

[0013] 6, the large plate 10 is separated at the separation plane 13 into a first small plate 20 and a second small plate 30. Therefore, the first small plate 20 and the second small plate 30 are smaller than the large plate 10. Either the first small plate 20 or the second small plate 30 may be larger.

[0014] For example, the first small plate 20 may be a product and the second small plate 30 may be a non-product, i.e., a discarded product. Alternatively, the second small plate 30 may be a product and the first small plate 20 may be a non-product. Alternatively, both the first small plate 20 and the second small plate 30 may be products.

[0015] Since the large plate 10 is a glass plate, the first small plate 20 and the second small plate 30 are naturally both glass plates.

[0016] The glass plate product is used, for example, as automobile window glass, instrument panel, head-up display (HUD), dashboard, center console, shift knob and other automobile interior part cover glass, architectural window glass, display substrate, or display cover glass. The thickness of the glass plate product is appropriately set depending on the application of the product, and is, for example, 0.01 cm to 2.5 cm.

[0017] The glass sheet as a product may be laminated with another glass sheet via an interlayer film after steps S1 to S5 in Fig. 1 and used as laminated glass. Alternatively, the glass sheet as a product may be subjected to a tempering treatment after steps S1 to S5 in Fig. 1 and used as tempered glass.

[0018] The glass of the product may be, for example, soda-lime glass, alkali-free glass, or chemically strengthened glass. The chemically strengthened glass is used as, for example, a cover glass after being chemically strengthened. The glass of the product may also be tempered glass.

[0019] The glass sheet as a product may be bent after steps S1 to S5 in Fig. 1, or the glass sheet as a product may be obtained after bending the large sheet 10, i.e., by performing steps S1 to S5 in Fig. 1 on the large sheet 10 that has been curved into a single curve or a complex curve. In other words, the glass sheet as a product may have a curved shape into a single curve or a complex curve.

[0020] As shown in Figures 2A and 2B, the separation surface 13 has a first intersection line 14 that intersects with the first major surface 11 and a second intersection line 15 that intersects with the second major surface 12. The first intersection line 14 has, for example, a curved portion. The first intersection line 14 does not have a straight portion, but may have a straight portion as described below. The second intersection line 15 also has a curved portion, similar to the first intersection line 14. The second intersection line 15 has a curved portion with the same center of curvature C as the first intersection line 14. The second small plate 30 includes the center of curvature C.

[0021] 2A , in a plan view, the first intersection line 14 is disposed on one side of the second intersection line 15. Specifically, for example, the first intersection line 14 is disposed on the side of the center of curvature C relative to the second intersection line 15, that is, on the radially inner side of the second intersection line 15. Note that the positions of the first intersection line 14 and the second intersection line 15 may be reversed, and the first intersection line 14 may be disposed on the side opposite the center of curvature C relative to the second intersection line 15, that is, on the radially outer side of the second intersection line 15.

[0022] 2B, in a cross section 16 perpendicular to the first intersection line 14, the separation surface 13 is inclined with respect to a normal line N to the first main surface 11. The separation surface 13 is, for example, a linear taper. The angle β between the normal line N to the first main surface 11 and the separation surface 13 is, for example, 3° to 45°.

[0023] If β is 3° or more, the first small plate 20 and the second small plate 30 can be shifted in the normal direction of the first main surface 11, as shown in Fig. 6, as will be described in detail later. On the other hand, if β is 45° or less, chipping at the separation surface 13 of the product can be suppressed. Furthermore, as shown in Fig. 7, when S6 (chamfering) is further performed after S5, β is preferably 3° to 20°.

[0024] Although separation surface 13 has a linear taper in this embodiment, it may have a non-linear taper. In this case, β is the angle between the normal N to first main surface 11 and the tangent to separation surface 13. It is sufficient that β is within the above range.

[0025] Next, in S2 of FIG. 1, as shown in FIG. 3, the first laser light LB1 is focused into a point inside the large plate 10, and a point-like modified area D is formed at the focused point. The first laser light LB1 is pulsed light, and forms the modified area D by nonlinear absorption. Nonlinear absorption is also called multiphoton absorption. The probability of multiphoton absorption occurring is nonlinear with respect to the photon density (power density of the first laser light LB1), and the higher the photon density, the greater the probability. For example, the probability of two-photon absorption occurring is proportional to the square of the photon density.

[0026] The pulsed light is preferably a pulsed laser light having a wavelength range of 250 nm to 3000 nm and a pulse width of 10 fs to 1000 ns. Laser light having a wavelength range of 250 nm to 3000 nm can penetrate the large plate 10 to a certain extent, causing nonlinear absorption inside the large plate 10 and forming the modified region D. The wavelength range is preferably 260 nm to 2500 nm. Furthermore, pulsed laser light having a pulse width of 1000 ns or less makes it easy to increase the photon density, causing nonlinear absorption inside the large plate 10 and forming the modified region D. The pulse width is preferably 100 fs to 100 ns.

[0027] The light source of the first laser light LB1 may include, for example, a Nd-doped YAG crystal (Nd:YAG) and output pulsed light with a wavelength of 1064 nm. The wavelength of the pulsed light is not limited to 1064 nm. An Nd:YAG second harmonic laser (wavelength 532 nm) or an Nd:YAG third harmonic laser (wavelength 355 nm) can also be used. The light source of the first laser light LB1 repeatedly outputs a group of pulses or a single pulsed light.

[0028] The first laser beam LB1 is focused into a point shape by an optical system including a focusing lens, etc. The modified portion D is a change in density or refractive index of the glass. The modified portion D is a void, a modified layer, etc. The modified layer is a layer whose density or refractive index has changed due to a structural change or melting and resolidification.

[0029] The modified portions D are arranged in a dispersed manner on the separation surface 13 by repeating two-dimensional movement of the focal point within a plane having a constant depth from the first main surface 11 and change of the depth of the focal point from the first main surface 11. A 3D galvanometer scanner, for example, is used to move the focal point. When the depth of the focal point is changed by moving a stage, a 2D galvanometer scanner may also be used.

[0030] The stage holds the large plate 10. The movement of the focal point may be performed by moving or rotating the stage holding the large plate 10. The stage may be, for example, an XY stage, an XYθ stage, an XYZ stage, or an XYZθ stage. The X, Y, and Z axes are orthogonal to each other, the X and Y axes are parallel to the first main surface 11, and the Z axis is perpendicular to the first main surface 11.

[0031] The modified region D is formed over the entire thickness direction from the first main surface 11 to the second main surface 12. Here, the entire thickness direction means a region covering 80% or more of the thickness of the plate. Within this region, multiple dot-like modified regions D may be formed at intervals in the thickness direction, or a continuous linear modified region D may be formed. In either case, cracks CR can be formed over the entire thickness direction in S3 of FIG. 1.

[0032] When forming the modified region D, the first laser light LB1 may be optically focused into a line in the optical axis direction by an optical system including a filament or a focusing lens. In this case, a linear modified region D is formed. When forming the modified region D, the first laser light LB1 may also use a multi-focus optical system to simultaneously generate multiple focused spots in the optical axis direction. A plurality of point-like modified regions D are formed simultaneously. The first laser light LB1 may be irradiated obliquely onto the first main surface 11, and the optical axis of the first laser light LB1 may be on the separation surface 13.

[0033] 1, stress is applied to the large plate 10 to form a crack CR on the separation surface 13, as shown in FIG. 4. The crack CR is formed from the modified portion D as a starting point, and extends from the first main surface 11 to the second main surface 12.

[0034] To form cracks CR, for example, thermal stress is applied to the large plate 10 by irradiating it with the second laser beam LB2. The second laser beam LB2 causes mainly linear absorption when irradiated onto the large plate 10. Mainly linear absorption means that the amount of heat generated by linear absorption is greater than the amount of heat generated by nonlinear absorption. Nonlinear absorption may hardly occur. When the photon density at any position on the large plate 10 is 1×10 8 W / cm 2 In this case, almost no nonlinear absorption occurs. Heat generated by the second laser beam LB2 forms the crack CR.

[0035] Linear absorption is also called one-photon absorption. The probability of one-photon absorption occurring is proportional to the photon density. In the case of one-photon absorption, the following equation (1) holds true according to the Lambert-Beer's law: I = I0 × exp(-α × L) (1) In the above formula (1), I0 is the first 2 Laser light LB 2 I is the strength of the second main surface 12 2 Laser light LB 2 L is the strength of the first main surface 11 to the second main surface 12 2Laser light LB 2 The propagation distance of 2 Laser light LB 2 is the absorption coefficient of the glass for the linear absorption. 2 Laser light LB 2 It is determined by the wavelength of the light and the chemical composition of the glass.

[0036] α×L represents the internal transmittance. 2 Laser light LB 2 is the transmittance when it is assumed that light is not reflected by the first main surface 11. The smaller α×L is, the higher the internal transmittance is. α×L is, for example, 3.0 or less, more preferably 2.3 or less, and even more preferably 1.6 or less. In other words, the internal transmittance is, for example, 5% or more, preferably 10% or more, and more preferably 20% or more. If α×L is 3.0 or less, the internal transmittance is 5% or more, and both the first main surface 11 and the second main surface 12 are sufficiently heated.

[0037] From the viewpoint of heating efficiency, α×L is preferably 0.002 or more, more preferably 0.01 or more, and even more preferably 0.02 or more. In other words, the internal transmittance is preferably 99.8% or less, more preferably 99% or less, and even more preferably 98% or less.

[0038] If the temperature of the glass exceeds the annealing point, the plastic deformation of the glass will progress, and the generation of thermal stress will be limited. Therefore, the light wavelength, output, beam diameter at first main surface 11, etc. are adjusted so that the temperature of the glass will be below the annealing point.

[0039] The second laser light LB2 is, for example, continuous wave light. The light source of the second laser light LB2 is not particularly limited, but is, for example, a Yb fiber laser. The Yb fiber laser is an optical fiber in which the core is doped with Yb, and outputs continuous wave light with a wavelength of 1070 nm.

[0040] However, the second laser light LB2 may be a pulsed light instead of a continuous wave light.

[0041] The second laser light LB2 is irradiated onto the first main surface 11 by an optical system including a focusing lens and the like. The second laser light LB2 may be irradiated obliquely with respect to the first main surface 11. In this case, the optical axis of the second laser light LB2 may be on the separation surface 13. By moving the irradiation point of the second laser light LB2 along the first intersection line 14, a crack CR is formed across the entire separation surface 13. The crack CR divides the large plate 10 into a first small plate 20 and a second small plate 30.

[0042] The irradiation point can be moved using, for example, a 2D galvanometer scanner or a 3D galvanometer scanner. The irradiation point can also be moved by moving or rotating a stage that holds the large plate 10. The stage can be, for example, an XY stage, an XYθ stage, an XYZ stage, or an XYZθ stage.

[0043] In this embodiment, thermal stress is applied to the large plate 10 by irradiating it with the second laser light LB2, but the method for applying stress to the large plate 10 is not particularly limited. Stress may also be applied to the large plate 10 by pressing a roller against the large plate 10.

[0044] The radius of curvature of the curved portion is, for example, 0.5 mm or more, preferably 1.0 mm or more, so that the crack CR can easily bend along the curved portion of the first intersection line 14. The radius of curvature of the curved portion is, for example, 1000 mm or less, preferably 500 mm or less.

[0045] Next, in S4 of Fig. 1, as shown in Fig. 5, a temperature difference is created between the first small plate 20 and the second small plate 30, forming a gap G between the first small plate 20 and the second small plate 30. This can prevent the glass plates from rubbing against each other.

[0046] When the portion on the side of the center of curvature C (e.g., second small plate 30) is at a lower temperature than the portion on the opposite side of the center of curvature C (e.g., first small plate 20) based on the curved portion of the first intersection line 14, a gap G is formed between the first small plate 20 and the second small plate 30. The portion on the side of the center of curvature C may be cooled, or the portion on the opposite side of the center of curvature C may be heated.

[0047] Note that S4 in FIG. 1 does not have to be performed, and S5 in FIG. 1 may be performed following S3 in FIG.

[0048] Next, in S5 of Fig. 1, the first small plate 20 and the second small plate 30 are shifted in the normal direction of the first main surface 11, and the first small plate 20 and the second small plate 30 are separated, as shown in Fig. 6. As described above, as shown in Fig. 2A, the first intersection line 14 is located on one side of the second intersection line 15 in a plan view, and as shown in Fig. 2B, in a cross section 16 perpendicular to the first intersection line 14, the separation surface 13 is inclined with respect to the normal line N of the first main surface 11. For example, the separation surface 13 tapers vertically upward, and the vertical direction is the normal direction of the first main surface 11.

[0049] Therefore, the first small plate 20 and the second small plate 30 can be shifted in the normal direction of the first main surface 11. 2 As shown in A, even when the first intersection line 14 of the first main surface 11 includes a curved portion and the first small plate 20 and the second small plate 30 cannot be shifted in a direction parallel to the first main surface 11, the first small plate 20 and the second small plate 30 can be separated without crushing either the first small plate 20 or the second small plate 30.

[0050] Because the first small plate 20 is a product and the second small plate 30 is a non-product, the separation surface 13 tapers vertically upward so that the non-product can be removed by gravity. If the first small plate 20 is a non-product and the second small plate 30 is a product, the taper of the separation surface 13 may be reversed, or the separation surface 13 may taper vertically downward. If the first small plate 20 is an automobile window glass or a cover glass for an automobile interior part, the inclination angle β of the separation surface 23 can be determined according to the installation angle of the first small plate 20 when installed in the automobile. This can minimize the loss of electromagnetic waves transmitted and received by accessories capable of transmitting and receiving electromagnetic waves, such as sensors and millimeter-wave radar, located on the second main surface 22 of the first small plate 20.

[0051] Next, referring back to Figure 6, the product, the first small plate 20, will be described. The first small plate 20 has a first main surface 21, a second main surface 22, and an inclined surface 23. The first main surface 21 of the first small plate 20 is part of the first main surface 11 of the large plate 10. Similarly, the second main surface 22 of the first small plate 20 is part of the second main surface 12 of the large plate 10. The inclined surface 23 of the first small plate 20 is formed by a crack CR in the separation surface 13.

[0052] Like the first small plate 20, the second small plate 30 also has a first main surface 31, a second main surface 32, and an inclined surface 33. The first main surface 31 of the second small plate 30 is the remainder of the first main surface 11 of the large plate 10. Similarly, the second main surface 32 of the second small plate 30 is the remainder of the first main surface 11 of the large plate 10. The inclined surface 33 of the second small plate 30 is formed by a crack CR in the separation surface 13.

[0053] (Second embodiment) As shown in Fig. 7, the method for processing a glass plate may further include S6 after S5. S6 in Fig. 7 will be described below with reference to Fig. 8. Note that S1 to S5 in Fig. 7 are similar to S1 to S5 in Fig. 1, and therefore description thereof will be omitted. However, S4 in Fig. 7 does not have to be performed as in S4 in Fig. 1, and S5 in Fig. 7 may be performed following S3 in Fig. 7.

[0054] In S6 of Fig. 7, as shown in Fig. 8, the corner between the inclined surface 23 and the first main surface 21 of the first small plate 20 is chamfered to form a first chamfered surface 24 at the corner. Similarly, the corner between the inclined surface 23 and the second main surface 22 of the first small plate 20 is chamfered to form a second chamfered surface 25 at the corner. A machining center or the like is used for the chamfering. The chamfering may be a so-called C-chamfer, but in this embodiment, an R-chamfer is used.

[0055] Next, referring again to Figure 8, the first small plate 20, which is the product, will be described. Because the first small plate 20 is a glass plate, hereinafter the first small plate 20 will also be referred to as the glass plate 20. The glass plate 20 has a first main surface 21, a second main surface 22, an inclined surface 23, a first chamfered surface 24, and a second chamfered surface 25. The formation of the first chamfered surface 24 and the second chamfered surface 25 can prevent chipping of the glass plate 20.

[0056] (Third embodiment) In the first and second embodiments, the first intersection line 14 and the second intersection line 15 are closed as shown in Fig. 2A. Therefore, the first small plate 20 and the second small plate 30 cannot be shifted in a direction parallel to the first main surface 11.

[0057] On the other hand, in this embodiment, the first intersection line 14 and the second intersection line 15 are both open, as shown in Fig. 9. The ends of the first intersection line 14 and the second intersection line 15 are coincident (in other words, do not exist) in Fig. 2A, but are separated in Fig. 9.

[0058] 9 is open and intersects the periphery of the first main surface 11 at two points to divide the first main surface 11 into two regions. The distance L1 between both ends of the first intersection line 14 is equal to or less than twice the average radius of curvature R1 of the curved portion of the first intersection line 14 (twice in this embodiment).

[0059] 9 is open and intersects the periphery of the second main surface 12 at two points to divide the second main surface 12 into two regions. The distance L2 between both ends of the second intersection line 15 is equal to or less than twice the average radius of curvature R1 of the curved portion of the second intersection line 15 (twice in this embodiment).

[0060] Even when L1 is equal to or less than twice R1 and L2 is equal to or less than twice R2, it is difficult to shift the first small plate 20 and the second small plate 30 in a direction parallel to the first main surface 11. This is because the width of the outlet is narrow.

[0061] Therefore, in this embodiment, similarly to the first and second embodiments, the desired effects can be obtained by processing the large plate 10 using the processing method shown in FIG. 1 or FIG. [Example]

[0062] A specific example of a method for processing a glass plate will be described below.

[0063] [Example 1] In Example 1, steps S1 to S5 in FIG. 1 were carried out. In S1, a 3.5 mm thick soda lime glass was prepared as the large plate 10. The first main surface 11 was a rectangle measuring 200 mm in length and 100 mm in width. The separation surface 13 was a truncated cone surface tapering vertically upward. The angle β between the normal to the first main surface 11 and the separation surface 13 was 4°. The first intersection line 14 was a circle with a radius of 22.5 mm.

[0064] In S2, as shown in Fig. 3, the first laser beam LB1 was focused into a point inside the large plate 10, and point-like modified areas D were formed at the focused points. The modified areas D were dispersed and arranged on the separation surface 13 by repeatedly moving the focused point two-dimensionally within a plane with a constant depth from the first main surface 11 and changing the depth of the focused point from the first main surface 11. An XYZ stage was used to move the focused point.

[0065] The irradiation conditions of the first laser beam LB1 in S2 were as follows: Oscillator: Green pulse laser (Spectra Physics, Explorer 532-2Y) Oscillation method: Pulse oscillation (single) Light wavelength: 532nm Output: 2W Oscillation frequency: 10kHz In-plane scanning speed: 100 mm / s In-plane irradiation pitch: 0.01 mm Depth direction irradiation pitch: 0.05 mm Focused beam diameter: 4 μm Pulse energy: 200μJ.

[0066] In S3, as shown in FIG. 4, stress was applied to the large plate 10 to form cracks CR on the separation surface 13. To form the cracks CR, thermal stress was applied to the large plate 10 by irradiating it with a second laser beam LB2. The second laser beam LB2 was irradiated onto the first main surface 11 by an optical system including a focusing lens. The irradiation point was moved along the first intersection line 14 to form cracks CR over the entire separation surface 13. An XYZ stage was used to move the irradiation point.

[0067] The irradiation conditions of the second laser beam LB2 in S3 were as follows: Oscillator: Yb fiber laser (IPG Photonics, YLR500) Oscillation method: Continuous wave oscillation Light wavelength: 1070nm Output: 340W In-plane scanning speed: 70 mm / s Beam diameter at first main surface 11: 1.2 mm.

[0068] In S4, as shown in Fig. 5, a temperature difference was created between the first small plate 20 and the second small plate 30, and a gap G was formed between the first small plate 20 and the second small plate 30. Specifically, cooling spray was sprayed onto the second small plate 30 for 10 seconds.

[0069] In S5, as shown in Fig. 6, the first small plate 20 and the second small plate 30 were shifted in the normal direction of the first main surface 11, and the first small plate 20 and the second small plate 30 were separated. Specifically, the second small plate 30 was pulled vertically downward by gravity. After that, the first small plate 20, which was the product, was grasped and transported by a transport robot, and no chipping was observed on the inclined surface 23 of the first small plate 20.

[0070] [Example 2] In Example 2, the large plate 10 was processed under the same conditions as in Example 1, except that the angle β between the normal to the first main surface 11 and the separation surface 13 was changed to 21°. As a result, similar to Example 1, the second small plate 30 could be pulled vertically downward by gravity. Furthermore, no chipping was observed on the inclined surface 23 of the first small plate 20 as a product during transportation.

[0071] [Example 3] In Example 3, the large plate 10 was processed under the same conditions as in Example 1, except that the angle β between the normal to the first main surface 11 and the separation surface 13 was changed to 45°. As a result, similar to Example 1, the second small plate 30 could be pulled vertically downward by gravity. Furthermore, no chipping was observed on the inclined surface 23 of the first small plate 20 as the product during transportation.

[0072] [Example 4] In Example 4, the large plate 10 was processed under the same conditions as in Example 1, except that the angle β between the normal to the first main surface 11 and the separation surface 13 was changed to 60°. As a result, the second small plate 30 could be pulled vertically downward by gravity, as in Example 1. However, chipping was observed on the inclined surface 23 of the first small plate 20 as the product during transportation.

[0073] [Example 5] In Example 5, the large plate 10 was processed under the same conditions as in Example 1, except that the angle β between the normal to the first main surface 11 and the separation surface 13 was changed to 2°. As a result, unlike Example 1, the second small plate 30 could not be removed vertically downward due to gravity. Therefore, it was naturally impossible to transport the first small plate 20 after removal.

[0074] 〔summary〕 The evaluation results of Examples 1 to 5 are shown in Table 1.

[0075] [Table 1] As is clear from Table 1, in Examples 1 to 3, β was within the range of 3° to 45°, so separation was possible and no chipping occurred during transport. On the other hand, in Example 4, β was too large, so chipping occurred during transport. In addition, in Example 5, β was too small, so separation was not possible.

[0076] The glass plate processing method and the glass plate according to the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure.

[0077] This application claims priority based on Japanese Patent Application No. 2019-210500, filed with the Japan Patent Office on November 21, 2019, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0078] 10 large boards 11 First main surface 12 Second main surface 13 Separation plane 14 1st intersection line 15 Second intersection line 20 First Small Board 30 Second Small Plate LB1 First laser beam D Modification section CR crack

Claims

1. A method for processing a glass plate, comprising separating a large glass plate having a first main surface and a second main surface facing opposite to the first main surface into a first small glass plate and a second small glass plate at a separation surface, the separation surface has a curved portion at each of a first intersection line intersecting with the first main surface and a second intersection line intersecting with the second main surface, In a plan view, the first intersection line is disposed on one side of the second intersection line, In a cross section perpendicular to the first intersection line, the separation surface is inclined with respect to a normal line to the first main surface, and an angle between the separation surface and the normal line to the first main surface is equal to or greater than 3° and equal to or less than 45°; A first laser beam, which is a pulsed beam, is focused inside the large plate to form a modified portion on the separation surface to be separated by nonlinear absorption; After the modified portion is formed, the large plate is irradiated with a second laser beam to mainly cause linear absorption, and thermal stress is applied to the large plate so that the temperature of the large plate becomes equal to or lower than the annealing point, thereby forming cracks on the separation surface; where L is a propagation distance of the second laser beam from the first main surface to the second main surface, and α is an absorption coefficient of glass with respect to the second laser beam, α×L is equal to or greater than 0.002 and equal to or less than 3.0, a method for processing a glass plate, wherein after the crack is formed, the first small plate and the second small plate are shifted in a direction normal to the first main surface to separate the first small plate and the second small plate.

2. The method for processing a glass plate according to claim 1 , wherein the first laser beam is focused into a point shape inside the large plate, and a plurality of point-shaped modified portions are formed on the separation surface to be separated.

3. The method for processing a glass plate according to claim 1 , wherein the first laser light is irradiated obliquely onto the first main surface when the modified portion is formed.

4. The processing method according to any one of claims 1 to 3, wherein the first intersection line and the second intersection line are each closed.

5. the first intersection line and the second intersection line are each open, 4. The processing method according to claim 1, wherein the distance between both ends of the first intersection line is equal to or less than twice the average radius of curvature of the curved portion of the first intersection line.

6. The processing method according to any one of claims 1 to 5, wherein a radius of curvature of the curved portion of the first intersection line is 0.5 mm or more and 1000 mm or less.

7. A processing method described in any one of claims 1 to 6, wherein after the crack is formed, a temperature difference is applied to the first small plate and the second small plate before the first small plate and the second small plate are shifted, thereby forming a gap between the first small plate and the second small plate.

8. The processing method according to any one of claims 1 to 7, further comprising cutting a corner between the inclined surface caused by the crack in the first small plate and the first main surface of the first small plate to form a chamfered surface at the corner.

9. The processing method according to any one of claims 1 to 8, further comprising cutting a corner between the inclined surface caused by the crack in the first small plate and the second main surface of the first small plate to form a chamfered surface at the corner.

10. The processing method according to any one of claims 1 to 9, wherein the large plate is a bent plate.

11. The processing method according to any one of claims 1 to 10, wherein the glass plate is an automobile window glass or a cover glass for an automobile interior part.

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