WO2014175145A1

WO2014175145A1 - Method for cutting glass plate

Info

Publication number: WO2014175145A1
Application number: PCT/JP2014/060870
Authority: WO
Inventors: 齋藤　勲; 孝弘永田
Original assignee: 旭硝子株式会社
Priority date: 2013-04-26
Filing date: 2014-04-16
Publication date: 2014-10-30
Also published as: JP2016128362A

Abstract

Provided is a method that is for cutting a glass plate and that has superior dimensional precision. One embodiment of this method for cutting a glass plate is provided with a step for forming scribe lines (31, 32) respectively at the first primary surface (11) and second primary surface (12) of a glass plate (10) by means of scanning laser light (20) while causing the laser light (20) to be transmitted from the first primary surface (11) to the second primary surface (12). The beam widths (W1, W2) at the first primary surface (11) and second primary surface (12) of the scanning laser light (20) are each caused to be no greater than the thickness (t) of the glass plate (10).

Description

Cutting method of glass plate

The present invention relates to a method for cutting a glass plate, and more particularly to a method for cutting a glass plate using internal heating by laser light.

The glass plate is usually cut by introducing a scribe line mechanically into the main surface with a hard roller or chip such as diamond and applying a bending force along the scribe line. In such a technique, a lot of fine cracks are generated on the cut end face of the glass plate by introducing the scribe line. Therefore, there is a problem that sufficient strength cannot be obtained at the cut end.

In recent years, with respect to such problems, there is a method of cutting a glass plate by heating the inside of the glass plate by laser light irradiation and controlling the extension of initial cracks introduced into the end surface instead of the main surface of the glass plate. It has been proposed (for example, Patent Document 1). In such cutting using laser light (hereinafter also referred to as “laser cutting”), it is not necessary to mechanically introduce a scribe line into the main surface of the glass plate. Therefore, the above-mentioned fine crack is not generated on the cut end face, and a glass plate excellent in strength at the cut end can be obtained.

Japanese Unexamined Patent Publication No. 2006-256944

The inventor has found the following problems.
For example, in the method of cutting a glass plate described in Patent Document 1, the distance between the tip of a crack that develops by laser light irradiation and the irradiation position of the laser light is large, and the crack formation position (that is, the cutting position) is the laser light irradiation position. It was easy to deviate from the trajectory. That is, the conventional method for cutting a glass plate has a problem that the dimensional accuracy of cutting is inferior.

The present invention has been made in view of the above, and an object of the present invention is to provide a method for cutting a glass plate with excellent dimensional accuracy.

One aspect of the present invention provides the following glass plate production method.
(1) A scribe line is formed on each of the first main surface and the second main surface by scanning the laser light while transmitting the laser light from the first main surface to the second main surface of the glass plate. With steps,
The beam width on the first main surface and the second main surface of the laser beam to be scanned is set to be equal to or less than the plate thickness of the glass plate, respectively.
A method for cutting a glass plate, wherein the scribe line formed on the first main surface and the scribe line formed on the second main surface are combined.
(2) In the step of forming the scribe line,
The glass plate is heated by the laser beam, and the first main surface and the second main surface are swelled, and the first main surface and the second main surface are caused by tensile stress acting on the swelled portion. Forming the scribe line,
The cutting method of the glass plate as described in said (1).
(3) The optical axis of the laser beam is perpendicular to the first main surface and the second main surface.
The cutting method of the glass plate as described in said (1) or (2).
(4) The method further includes a step of forming an initial crack serving as a starting point of the scribe line on the end face of the glass plate.
The method for cutting a glass plate according to any one of the above (1) to (3).
(5) The wavelength of the laser beam is 250 to 5000 nm.
The method for cutting a glass plate according to any one of the above (1) to (4).
(6) The beam shape of the laser beam on the first main surface and the second main surface is circular.
The method for cutting a glass plate according to any one of the above (1) to (5).

According to the present invention, it is possible to provide a method for cutting a glass plate with excellent dimensional accuracy.

It is a perspective view for demonstrating the method of forming a scribe line in the upper and lower surfaces of a glass plate, respectively. It is a top view which shows the beam shape of the laser beam in the upper surface of the glass plate of FIG. It is a top view which shows the beam shape of the laser beam in the lower surface of the glass plate of FIG. FIG. 4 is an axial sectional view taken along line IV-IV in FIG. 2. FIG. 5 is a cross-sectional view taken along line VV in FIG. 2. It is sectional drawing of the cooling nozzle used for the cutting | disconnection of a glass plate. FIG. 5 is an enlarged view of FIG. 4. It is a schematic diagram of the full cut disclosed in Patent Document 1. It is a top view of the glass plate 10 which shows test conditions typically. 14 is a table showing cutting conditions and cutting results for glass sheets in Test Examples 11 to 14.

Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

<Embodiment 1>
First, a method of forming scribe lines on the upper and lower surfaces of a glass plate will be described with reference to FIGS. FIG. 1 is a perspective view for explaining a method of forming scribe lines on the upper and lower surfaces of a glass plate. FIG. 2 is a plan view showing a beam shape of laser light on the upper surface of the glass plate of FIG. FIG. 3 is a plan view showing a beam shape of laser light on the lower surface of the glass plate of FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a sectional view taken along line VV in FIG.

1 to 4, the arrow direction indicates the displacement direction of the irradiation position of the laser beam on the glass plate. In FIG. 5, the arrow direction indicates the direction of action of stress. 4 and 5, the thermal deformation of the glass plate is exaggerated. The state of thermal deformation of the glass plate can be confirmed by finite element analysis.
In the right-handed xyz orthogonal coordinate space shown in FIGS. 1 to 5, both main surfaces (upper surface 11 and lower surface 12) of the glass plate 10 are both parallel to the xy plane. The laser light is irradiated in the z-axis minus direction and scanned in the x-axis plus direction. The optical axis of the laser beam is parallel to the z axis.

The glass plate cutting method includes a scribing step of forming

scribe lines

31 and 32 on the glass plate 10. Although the kind of glass of the glass plate 10 is not specifically limited, For example, soda-lime glass, an alkali free glass, etc. are mentioned. The thickness of the glass plate 10 is appropriately set according to the use of the glass plate 10, and is, for example, 0.005 cm to 2.5 cm. The glass plate 10 may be either non-tempered glass or tempered glass, but non-tempered glass is preferred. In the case of tempered glass, the value of the internal residual tensile stress is preferably less than 15 MPa. As a result, crack extension due to residual tensile stress does not occur, so that scribe lines can be stably formed on the upper and lower surfaces of the glass plate.

In the scribing process, the glass plate 10 is locally heated by the laser light 20 that passes through the glass plate 10 from the upper surface 11 side to the lower surface 12 side, and the irradiation position of the laser light 20 on the glass plate 10 is displaced. The scribe lines 31 are formed on the lower surface 12 of the glass plate 10 at the same time as the scribe lines 31 are formed on the upper surface 11 of the glass plate 10 due to the thermal stress generated in the glass plate 10. Thereby, it is possible to cleave the glass plate 10 by applying an external force to the glass plate 10 without turning the glass plate 10 upside down. For example, by placing the glass plate 10 on an elastic body without turning over and pushing the glass plate 10 from above, tensile stress is generated on the lower surface 12 of the glass plate 10, and the glass plate 10 can be cleaved along the scribe line 32. .

In this embodiment, since the scribe line 31 is also formed on the upper surface 11 of the glass plate 10, the cutting accuracy on the upper surface 11 and the lower surface 12 of the glass plate 10 is good. Furthermore, in the present embodiment, the scribe lines are simultaneously formed on the upper surface 11 and the lower surface 12 of the glass plate 10 with one laser beam 20, so that the scribe lines formed on the upper surface 11 and the lower surface 12 of the glass plate 10 are formed. The positional relationship tends to be a desired positional relationship. For example, when the laser beam 20 is perpendicularly incident on the upper surface 11 of the glass plate 10, a scribe line 31 formed on the upper surface 11 of the glass plate 10 when viewed from the normal direction of the upper surface 11 of the glass plate 10; The scribe line 32 formed on the lower surface 12 of the glass plate 10 tends to overlap. Therefore, the fractured surface of the glass plate 10 tends to be perpendicular to the upper surface 11 and the lower surface 12 of the glass plate 10.

The initial crack 33 which becomes the starting point of the scribe lines 31 and 32 may be formed in advance on the end surface 13 of the glass plate 10 as shown in FIG. The initial crack 33 may reach the upper surface 11 and the lower surface 12 of the glass plate 10, and may also be formed on the upper surface 11 and the lower surface 12 of the glass plate 10. The initial crack 33 is a common starting point for the scribe lines 31 and 32.

In addition, when an initial crack is formed in the end surface 13 of the glass plate 10, it may reach only the upper surface 11 of the glass plate 10, may reach only the lower surface 12 of the glass plate 10, or the glass plate 10 The upper surface 11 and the lower surface 12 may not be reached. Further, the initial crack may be formed on each of the upper surface 11 and the lower surface 12 of the glass plate 10, and in this case, it may reach the end surface 13 or may not reach the end surface 13. The initial crack may be formed on at least one of both the upper surface 11 and the lower surface 12 of the glass plate 10 and the end surface 13 of the glass plate 10.

The formation method of the initial crack 33 may be a general method, for example, a method using a cutter, a file, a laser, or the like. When the end surface 13 of the glass plate 10 is ground with a grindstone, microcracks formed by grinding can be used as initial cracks.

Part of the upper surface 11 of the glass plate 10 is heated by the laser beam 20 and bulges upward and symmetrically about the movement locus of the irradiation position of the laser beam 20 as shown in FIGS. In the portion that bulges upward, a tensile stress in a direction orthogonal to the direction of displacement of the irradiation position of the laser beam 20 is generated. Due to this tensile stress, the crack starting from the initial crack 33 extends along the movement locus of the irradiation position of the laser beam 20, and the scribe line 31 is formed. The tip of the scribe line 31 is at the irradiation position of the laser beam 20 on the upper surface 11 of the glass plate 10 or in the vicinity of the front thereof.

Similarly, a part of the lower surface 12 of the glass plate 10 is heated by the laser beam 20, and as shown in FIGS. 4 and 5, protrudes downward symmetrically about the movement locus of the irradiation position of the laser beam 20. Swell. In the portion that bulges downward, a tensile stress in a direction orthogonal to the direction of displacement of the irradiation position of the laser beam 20 is generated. Due to the tensile stress, the crack starting from the initial crack 33 extends along the movement locus of the irradiation position of the laser beam 20, and the scribe line 32 is formed. The tip of the scribe line 32 is at the irradiation position of the laser beam 20 on the lower surface 12 of the glass plate 10 or in the vicinity of the front thereof.

The scribe lines 31 and 32 both extend with the displacement of the irradiation position of the laser beam 20 on the glass plate 10. The displacement of the irradiation position of the laser beam 20 on the glass plate 10 is performed by the movement or rotation of the support of the glass plate 10 relative to the frame of the cutting device, or the movement of the light source 22 of the laser beam 20, even if both are performed. Good. Further, the displacement of the irradiation position of the laser beam 20 on the glass plate 10 may be performed by rotation of a galvanometer mirror that reflects the laser beam 20 emitted from the light source 22 toward the glass plate 10.

Whether or not a scribe line can be formed on each of the upper surface 11 and the lower surface 12 of the glass plate 10 is mainly determined by the formation position of the initial crack 33 and the irradiation condition of the laser beam 20. The irradiation conditions of the laser beam 20 include, for example, (1) the output of the light source 22, (2) the transmittance of the laser beam 20 with respect to the glass plate 10, and (3) the beam of the laser beam 20 on the upper surface 11 and the lower surface 12 of the glass plate 10. (4) Ratio (P1 / P2) of the power density (P1) of the laser beam 20 on the upper surface 11 of the glass plate 10 and the power density (P2) of the laser beam 20 on the lower surface 12 of the glass plate 10 It is done.

Assuming that the intensity of the laser beam 20 on the upper surface 11 of the glass plate 10 is I ₀ and the intensity of the laser beam 20 when moving through the glass plate 10 by a distance (D) (unit [cm]) is I, I = I The expression ₀ × exp (−α × D) is established. This equation is called Lambert-Beer's law. α represents the absorption coefficient (unit [cm ⁻¹ ]) of the glass plate 10 with respect to the laser light 20, and is determined by the wavelength of the laser light 20, the chemical composition of the glass plate 10, and the like. α is measured by an ultraviolet visible near infrared spectrophotometer or the like.

The absorption coefficient (α) (unit [cm ⁻¹ ]) of the glass plate 10 with respect to the laser beam 20, the distance (M) (unit [cm]) that the laser beam 20 moves from the upper surface 11 to the lower surface 12 of the glass plate 10, The product of (α × M) is preferably larger than 0 and not larger than 3.0. The internal transmittance of the laser beam 20 with respect to the glass plate 10 is high, and the lower surface 12 of the glass plate 10 can be sufficiently heated. α × M is more preferably 2.3 or less (internal transmittance of 10% or more), and further preferably 1.6 or less (internal transmittance of 20% or more). If α × M is too small, the internal transmittance is too high and the absorption efficiency is too low. Therefore, it is preferably 0.002 or more (internal transmittance 99.8% or less), more preferably 0.01 or more (internal transmittance). 99% or less), more preferably 0.02 or more (internal transmittance of 98% or less). The internal transmittance is a transmittance when there is no reflection on the upper surface 11 of the glass plate 10.

In addition, it is preferable that the heating temperature of the glass plate 10 is the temperature below the annealing point of glass. When the heating temperature of the glass plate exceeds the temperature of the annealing point of the glass, the glass is viscously flowed, the thermal stress is relaxed, and the scribe lines 31 and 32 are difficult to form.

When the laser beam 20 is perpendicularly incident on the upper surface 11 of the glass plate 10, the distance (M) that the laser beam 20 moves from the upper surface 11 to the lower surface 12 of the glass plate 10 is the same as the thickness (t) of the glass plate 10. Value. On the other hand, when the laser beam 20 is incident obliquely on the upper surface 11 of the glass plate 10, the laser beam 20 is refracted according to Snell's law. Therefore, when the refraction angle is γ, the laser beam 20 moves from the upper surface 11 to the lower surface 12 of the glass plate 10. The distance (M) to be obtained is approximately obtained by the equation M = t / cos γ.

As the light source 22, for example, a near-infrared (hereinafter simply referred to as “near-infrared”) laser having a wavelength of 800 to 1100 nm is used. As the near-infrared laser, for example, a Yb fiber laser (wavelength: 1000 to 1100 nm), a Yb disk laser (wavelength: 1000 to 1100 nm), an Nd: YAG laser (wavelength: 1064 nm), a high-power semiconductor laser (wavelength: 808 to 980 nm) ). These near-infrared lasers are high-powered and inexpensive, and it is easy to adjust α × M within a desired range.

In the present embodiment, a high-power and inexpensive near-infrared laser is used as the light source 22, but a light source having a wavelength of 250 to 5000 nm can be used. For example, UV laser (wavelength: 355 nm), green laser (wavelength: 532 nm), Ho: YAG laser (wavelength: 2080 nm), Er: YAG laser (2940 nm), laser using a mid-infrared light parametric oscillator (wavelength: 2600) To 3450 nm). The oscillation method of the laser beam 20 is not limited, and either a CW laser that continuously oscillates the laser beam or a pulse laser that oscillates the laser beam intermittently can be used. The intensity distribution of the laser beam 20 is not limited, and may be a Gaussian type or a top hat type.

In the case of a near-infrared laser, the absorption coefficient (α) increases as the content of iron (Fe), the content of cobalt (Co), and the content of copper (Cu) in the glass plate 10 increase. In this case, the absorption coefficient (α) increases in the vicinity of the absorption wavelength of the rare earth atom as the content of the rare earth element (for example, Yb) in the glass plate 10 increases. The adjustment of the absorption coefficient (α) uses iron from the viewpoints of glass transparency and cost, and cobalt, copper, and rare earth elements may not be substantially contained in the glass plate 10.

By the way, the smaller the beam width W1 of the laser beam 20 in the y-axis direction on the upper surface 11, the steeper the portion that bulges upward, and the direction perpendicular to the displacement direction (x-axis direction) of the laser beam 20 (y-axis direction). ) Tensile stress is large. Similarly, the smaller the beam width W2 of the laser beam 20 in the y-axis direction on the lower surface 12, the steeper the portion that bulges downward, and the direction (y-axis) orthogonal to the displacement direction (x-axis direction) of the laser beam 20 Direction) tensile stress is large.

Therefore, for the laser light 20, both the beam width W 1 in the y-axis direction on the upper surface 11 and the beam width W 2 in the y-axis direction on the lower surface 12 are both equal to or less than the plate thickness of the glass plate 10. As a result, the portion that bulges upward on the upper surface 11 and the portion that bulges downward on the lower surface 12 are sufficiently steep, and the tensile force sufficient to form scribe lines on the upper surface 11 and the lower surface 12 of the glass plate 10. Stress is generated. In addition, since tensile stress is generated at the irradiation position of the laser beam 20 on the upper surface 11 and the lower surface 12 of the glass plate 10, it is necessary to cool the vicinity of the rear of the irradiation position of the glass plate 10 with a refrigerant in order to generate the tensile stress as in the prior art. There is no.

The beam width L1 in the displacement direction (x-axis direction) of the laser beam 20 on the upper surface 11 and the beam width L2 in the displacement direction (x-axis direction) of the laser beam 20 on the lower surface 12 are not particularly limited. If L1 and L2 are short, the

curved scribe lines

31 and 32 can be easily formed. Moreover, if L1 and L2 are long, when the heating time of the specific position in the glass plate 10 is the same, the displacement speed of the irradiation position of the laser beam 20 in the glass plate 10 is fast, and the scribe lines 31 and 32 can be formed in a short time. .

The beam shape of the laser beam 20 on the upper surface 11 and the lower surface 12 of the glass plate 10 is not particularly limited, but is preferably circular. When the curved portion of the scribe line is formed, the width of the locus of the irradiation position of the laser beam 20 is constant, and the position accuracy of the scribe line is good.

While the laser beam 20 passes through the glass plate 10 from the upper surface 11 side to the lower surface 12 side, the intensity (W) of the laser beam 20 is attenuated according to Lambert-Beer's law. And the temperature of the part which the laser beam 20 of the glass plate 10 permeate | transmits is mainly determined by the power density (unit [W / cm < ² >]) of the laser beam 20, etc. FIG.

Therefore, the laser beam 20 has a ratio (P1 / P2) of the power density (P1) on the upper surface 11 of the glass plate 10 and the power density (P2) on the lower surface 12 of the glass plate 10 to 0.5-2. 0 is preferred. P1 / P2 is calculated by the equation P1 / P2 = S2 / S1 / exp (−α × M). S1 represents the irradiation area of the laser beam 20 on the upper surface 11 of the glass plate 10, and S2 represents the irradiation area of the laser beam 20 on the lower surface 12 of the glass plate 10. When P1 / P2 is 0.5 to 2.0, the temperature of the irradiation position of the laser beam 20 on the upper surface 11 of the glass plate 10 and the temperature of the irradiation position of the laser beam 20 on the lower surface 12 of the glass plate 10 are the same. It will be about. Accordingly, the portion that bulges upward on the upper surface 11 of the glass plate 10 and the portion that bulges downward on the lower surface 12 of the glass plate 10 are steep to the same extent. As a result, the depth of the scribe line 31 formed on the upper surface 11 of the glass plate 10 and the depth of the scribe line 32 formed on the lower surface 12 of the glass plate 10 are approximately the same depth. P1 / P2 is more preferably 0.6 or more, and further preferably 0.67 or more. Further, P1 / P2 is more preferably 1.67 or less, and further preferably 1.5 or less.

In order to adjust the ratio (S1 / S2) between the irradiation area (S1) of the laser beam 20 on the upper surface 11 of the glass plate 10 and the irradiation area (S2) of the laser beam 20 on the lower surface 12 of the glass plate 10, A condensing lens or the like (not shown) is disposed between the glass plate 10 and the like. When the condensing position of the laser beam 20 is below the glass plate 10, S1 / S2 is larger than 1.

Further, in the method for cutting a glass plate according to the present embodiment, the glass plate may be cooled by blowing air to the irradiation region of the laser beam 20. FIG. 6 is a cross-sectional view of a cooling nozzle used for cutting a glass plate. Gas is blown to the upper surface 11 of the glass plate 10 by the cooling nozzle 28 shown in FIG. As shown in FIG. 6, the cooling nozzle 28 is formed with a tapered cavity so that gas (air, nitrogen, etc.) flows in the direction of the arrow. Here, the axis of the cooling nozzle 28 coincides with the optical axis of the laser beam 20, and the laser beam 20 collected by the lens 25 passes through the inside of the cooling nozzle 28 and is provided at the tip of the cooling nozzle 28. The light is emitted from an opening having a diameter φn. Further, it can move in synchronization with the movement of the irradiation region of the laser beam 20 (that is, at the same scanning speed as the laser beam). With such a configuration, the laser irradiation unit is cooled by the gas. It is preferable to cool an area wider than the laser irradiation part. By this cooling, tensile stress is easily generated in the laser light irradiation region. That is, a scribe line is easily generated and stable processing is possible.

The cooling gas flow rate, the diameter φn of the opening of the cooling nozzle 28, and the gap G2 between the tip of the cooling nozzle 28 and the upper surface 11 of the glass plate 10 can be arbitrarily determined. Here, the smaller the diameter φn of the opening of the cooling nozzle 28, the faster the flow rate of the gas blown to the glass plate 10, and the cooling capacity on the upper surface 11 of the glass plate 10 is improved. Moreover, the cooling capability in the upper surface 11 of the glass plate 10 improves, so that the gap G2 between the front-end | tip of the cooling nozzle 28 and the upper surface 11 of the glass plate 10 is small. For example, room temperature cooling air is blown at a flow rate of 20 L / min using a cooling nozzle 28 having a diameter φn = 1 mm to a laser irradiation portion having a beam diameter of 0.3 mm. It is more effective if a similar cooling nozzle is provided on the lower surface 12 side.

Subsequently, the glass plate cutting method according to the present embodiment will be described in detail with reference to FIG. FIG. 7 is an enlarged view of FIG. As shown in FIG. 7, in the cutting method according to the present embodiment, by irradiating the laser beam 20, the inside of the glass plate 10 is heated, and compressive stress is generated due to the thermal expansion of the heated inside. On the other hand, the upper surface 11 and the lower surface 12 bulge convexly around the movement locus of the irradiation position of the laser light 20. Since the tensile stress in the direction (y-axis direction) orthogonal to the displacement direction of the irradiation position of the laser beam 20 is generated in the convexly bulging portion, the scribe lines 31 and 32 are developed.

Further, as shown in FIG. 7, in the rear of the irradiation position of the laser beam 20 (more specifically, at the rear end of the compressive stress generating portion), unlike the vicinity of the irradiation position of the laser beam 20, the entire plate thickness is obtained. Tensile stress is generated. This tensile stress is also formed behind the irradiation position of the laser beam 20 as a reaction force of the compressive stress generated by heating at the irradiation position of the laser beam 20. Therefore, when the tensile stress at the rear end of the compressive stress generating portion is large (that is, when the compressive stress due to irradiation with the laser beam 20 is large), the scribe line 31 formed on the upper surface 11 and the scribe line 32 formed on the lower surface 12. And extend in the direction of the plate thickness and bond.

In other words, as shown in FIG. 7, a predetermined section from the irradiation position of the laser beam 20 is a scribe formation section in which the scribe lines 31 and 32 are separately formed on the upper surface 11 and the lower surface 12. On the other hand, the section behind the scribe forming section is a full cut section in which the glass plate 10 is fully cut by the scribe lines 31 and 32 being joined. Therefore, in the cutting method according to the present embodiment, a full cut is performed only by laser irradiation without going through the breaking step (step of applying an external force to the glass plate 10 and cleaving the glass plate 10 along the scribe lines 31 and 32). can do.

Here, the shape of the crack formed by joining the scribe lines 31 and 32 is determined by the difference in the thermal stress field and the rigidity of the glass plate 10. Whether or not the scribe lines 31 and 32 are coupled by the thermal stress based on the irradiation of the laser beam 20 is mainly determined by the transmittance of the laser beam 20 with respect to the glass plate 10 and the output of the light source 22. When the output of the light source 22 is large and the tensile stress behind the irradiation position of the laser beam 20 becomes large, the scribe lines 31 and 32 are coupled. When the output of the light source 22 is small, the glass plate 10 may be irradiated with heating light emitted from a heating light source different from the light source 22 in order to combine the scribe lines 31 and 32.

The cutting of the glass plate 10 according to the present embodiment has better cutting accuracy on the upper surface 11 and the lower surface 12 of the glass plate 10 than the full cut disclosed in Patent Document 1. FIG. 8 is a schematic diagram of the full cut disclosed in Patent Document 1. FIG. As shown in FIG. 8, in Patent Document 1, tensile stress is generated by cooling the rear of the irradiation position of the laser beam with a refrigerant, and a crack that penetrates the glass plate 10 in the thickness direction is formed by this tensile stress. . That is, in Patent Document 1, no scribe line is formed by laser light irradiation. Therefore, the distance D2 between the tip of the crack and the optical axis of the laser beam 20 is large, the crack formation position (that is, the cutting position of the glass plate 10) is easily displaced from the locus of the laser beam 20, and the dimensional accuracy of the cutting is poor. It was.

In contrast, in the present embodiment, the scribe lines 31 and 32 are formed by the tensile stress generated at the irradiation position of the laser beam 20 on the upper surface 11 and the lower surface 12 of the glass plate 10. Therefore, as shown in FIG. 7, the distance D1 between the tips of the scribe lines 31 and 32 and the optical axis of the laser beam 20 is small, and the position of the scribe lines 31 and 32 and the locus of the laser beam 20 are likely to coincide. Therefore, the positional accuracy of the scribe lines 31 and 32 formed on the upper surface 11 and the lower surface 12 of the glass plate 10 is good, and the dimensional accuracy of cutting on the upper surface 11 and the lower surface 12 of the glass plate 10 is good.

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto.

(Example 1)
In Example 1, the cutting accuracy was investigated by changing the upper surface beam width W1 and the lower surface beam width W2 of the laser light 20 with respect to the plate thickness t of the glass plate 10 in Test Examples 11 to 14. Specifically, the difference Δε between the maximum shift amount εmax and the minimum shift amount εmim from the planned cutting line (laser scanning path) of the cutting end face was investigated as an error.

[Test Examples 11 to 14]
FIG. 9 is a plan view of the glass plate 10 schematically showing test conditions. In all the test examples 11 to 14, as shown in FIG. 9, laser light was applied to the upper surface of a rectangular glass plate (long side 100 mm, short side 50 mm, plate thickness 1.1 mm, soda lime glass manufactured by Asahi Glass Co., Ltd.). Incident vertically. A Yb fiber laser (wavelength: 1070 nm) was used as a laser light source. The absorption coefficient (α) of the glass plate with respect to the laser beam was 0.57 cm ⁻¹ , and α × M was 0.063 (that is, the internal transmittance was 94%).

The beam shape of the laser light was circular on the upper and lower surfaces of the glass plate 10. In all the test examples, as shown in FIG. 9, the laser beam was scanned from one long side of the glass plate 10 to the other long side in parallel with the short side of the glass plate 10. The distance d from the short side of the glass plate 10 at the laser scanning position was set to d = 10 mm.

FIG. 10 is a table showing the cutting conditions and cutting results of the glass plate in each of Test Examples 11 to 14. Specifically, in order from the left column of the table, laser output P (W), laser beam scanning speed v (mm / s), upper surface beam width W1 (mm), lower surface beam width W2 (mm), plate thickness t (Mm), the ratio W1 / t of the upper surface beam width W1 to the plate thickness t, the ratio W2 / t of the lower surface beam width W2 to the plate thickness t, the error Δε1 on the upper surface, the error Δε2 on the lower surface, and the cutting form It is shown.

The numerical values shown in the table of FIG. 10 will be described in order from the left column.
The laser output P was 300 W for Test Example 11, 340 W for Test Example 12, 360 W for Test Example 13, and 480 W for Test Example 14.
The scanning speed v of the laser beam was 20 mm / s for Test Examples 11 and 12, and 10 mm / s for Test Examples 13 and 14.

The upper surface beam width W1 was 0.60 mm for Test Example 11, 0.80 mm for Test Example 12, 1.00 mm for Test Example 13, and 1.20 mm for Test Example 14. The lower surface beam width W2 was 0.63 mm for Test Example 11, 0.83 mm for Test Example 12, 1.03 mm for Test Example 13, and 1.23 mm for Test Example 14. As described above, the thickness t of the glass plate was 1.1 mm in any test example.

Therefore, the ratio W1 / t between the upper surface beam width W1 and the plate thickness t is 0.55 for Test Example 11, 0.73 for Test Example 12, 0.91 for Test Example 13, and for Test Example 14. 1.09. Further, the ratio W2 / t between the lower surface beam width W2 and the plate thickness t is 0.57 for Test Example 11, 0.75 for Test Example 12, 0.94 for Test Example 13, and for Test Example 14. 1.12.

As a result of the cutting, the error Δε1 on the upper surface was 0.03 mm for Test Example 11, 0.05 mm for Test Example 12, 0.04 mm for Test Example 13, and 0.16 mm for Test Example 14. The error Δε2 on the lower surface was 0.03 mm for Test Example 11, 0.05 mm for Test Example 12, 0.04 mm for Test Example 13, and 0.16 mm for Test Example 14.
As shown in FIG. 7, the cutting forms of Test Examples 11 to 13 are all cut after the scribe lines 31 and 32 are formed on the upper surface 11 and the lower surface 12 and then they are joined together. . On the other hand, as shown in FIG. 8, the cutting form of Test Example 14 is a full cut behind the irradiation position of the laser beam 20 without forming a scribe line.

As can be seen from the results of Test Examples 11 to 13, both the ratio W1 / t of the upper surface beam width W1 and the plate thickness t and the ratio W2 / t of the lower surface beam width W2 and the plate thickness t are 1 or less (upper surface beam When both the width W1 and the lower surface beam width W2 are equal to or less than the plate thickness t), the scribe lines 31 and 32 are formed at the irradiation positions of the laser light 20 on the upper surface 11 and the lower surface 12. The scribe lines 31 and 32 are combined to be fully cut. Therefore, the error Δε1 on the upper surface and the error Δε2 on the lower surface are small, and the cutting accuracy is excellent.

On the other hand, as can be seen from the results of Test Example 14, both the ratio W1 / t of the upper surface beam width W1 and the plate thickness t and the ratio W2 / t of the lower surface beam width W2 and the plate thickness t are both greater than 1 (upper surface In the case where both the beam width W1 and the lower surface beam width W2 are larger than the plate thickness t), the scribe lines 31 and 32 are not formed at the irradiation positions of the laser light 20 on the upper surface 11 and the lower surface 12, and the error Δε1 on the upper surface and the lower surface Since the error Δε2 at this point becomes large, the cutting accuracy is poor.

As mentioned above, although embodiment etc. of the cutting method of a glass plate were demonstrated, this invention is not limited to the said embodiment etc., A various deformation | transformation and improvement are possible in the range described in the claim. .
For example, a plurality of laser beams for forming the scribe lines 31 and 32 on both surfaces of the glass plate 10 may be irradiated onto the glass plate 10 simultaneously.
Further, the glass plate 10 may be either a flat plate or a curved plate, and may be any one of a template glass with a concavo-convex pattern on the surface, a meshed glass containing a metal net or wire inside, or a laminated glass. .

This application is based on Japanese Patent Application No. 2013-093430 filed on Apr. 26, 2013, the contents of which are incorporated herein by reference.

DESCRIPTION OF SYMBOLS 10 Glass plate 11 Upper surface 12 Lower surface 13 End surface 20 Laser beam 22 Light source 25 Lens 28

Cooling nozzle

31, 32 Scribe line 33 Initial crack

Claims

Forming a scribe line on each of the first main surface and the second main surface by scanning the laser light while transmitting the laser light from the first main surface of the glass plate to the second main surface; ,
The beam width on the first main surface and the second main surface of the laser beam to be scanned is set to be equal to or less than the plate thickness of the glass plate, respectively.
A method for cutting a glass plate, wherein the scribe line formed on the first main surface and the scribe line formed on the second main surface are combined.
In the step of forming the scribe line,
The glass plate is heated by the laser beam, and the first main surface and the second main surface are swelled by a tensile stress acting on the swelled portion. Forming the scribe line,
The method for cutting a glass plate according to claim 1.
Making the optical axis of the laser beam perpendicular to the first main surface and the second main surface;
The cutting method of the glass plate of Claim 1 or 2.
Further comprising the step of forming an initial crack serving as a starting point of the scribe line on the end face of the glass plate,
The method for cutting a glass plate according to any one of claims 1 to 3.
The wavelength of the laser beam is 250 to 5000 nm.
The method for cutting a glass plate according to any one of claims 1 to 4.
The beam shape of the laser light on the first main surface and the second main surface is circular,
The method for cutting a glass plate according to any one of claims 1 to 5.