JP2013075817A - Method of cutting glass plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably inhibit breakage of a glass plate and generation of thermal residual strain by reducing as much as possible the loss of thermal energy incurred at preheating and at annealing before and after fuse-cutting.SOLUTION: The glass substrate G is fused/cut and separated into a product part Ga and a non-product part Gb with scheduled cutting line CL as boundary, by emitting a laser beam LB1 for fuse-cutting and a laser beam LB2 for annealing along the scheduled cutting line CL of the glass substrate G. At this time, the dimension of irradiation area SP2 of the annealing laser beam LB2 is made larger than the dimension of irradiation area SP1 of the fuse-cutting laser beam LB1 in the progression direction of fuse-cutting along the scheduled cutting line CL. And the irradiation area SP2 of the annealing laser beam LB2 is overlapped on the irradiation area SP1 of the fuse-cutting laser beam LB1 so that the irradiation area SP2 of the annealing laser beam LB2 straddles in front and back directions in which fuse-cutting of the irradiation area SP1 of the fuse-cutting laser beam LB1 progresses.

Description

  The present invention relates to an improvement of a cutting technique for fusing a glass plate.

  Conventionally, as a method of cutting a glass plate, after forming a scribe line on the surface of the glass plate, a method of cleaving the scribe line by applying a bending stress (cleaving by a bending stress) or an initial crack in the glass plate. After the formation, laser cleaving (cleaving due to thermal stress) is used in which the initial crack is propagated by laser irradiation heat and cleaved.

  However, the cleaving by bending stress has a problem that the generation of fine glass powder cannot be avoided, and the fine glass powder cannot be easily removed even after washing after cutting. Such a problem is particularly a problem in glass substrates for display applications and the like that require high cleanliness. In addition, in the cleaving due to bending stress, the cut end of the glass plate has an angular shape, and defects such as chipping are likely to occur, so it is necessary to chamfer the cut end of the glass plate after cutting. End up.

  On the other hand, with laser cleaving, the glass plate can be cleaved with almost no defects, but it is extremely difficult to avoid contact between the cut end faces of the glass plate when separating the cleaved glass plate. Therefore, at the time of separation, a minute defect may be formed on the cut end surface due to rubbing between the cut end surfaces of the glass plate. Further, even in the laser cleaving, the chamfering process needs to be performed after cutting since the cut end portion of the glass plate has an angular shape, similarly to the cleaving due to the bending stress.

  Laser cutting is attracting attention as a cutting method for coping with such problems.

  Laser fusing is a method of cutting a glass plate while melting and removing a part of the glass substrate with the heat of laser beam irradiation. Therefore, in laser fusing, a predetermined clearance is formed between the fusing end faces (cutting end faces) by melting and removing unnecessary glass, and the situation where the fusing end faces of the glass plates come into contact with each other at the time of separation can be reliably avoided. Further, the chamfering can be performed simultaneously by the heat at the time of fusing, and it is possible to give the end face an effect equal to or more than the effect by the conventional chamfering.

  However, even such laser fusing has a problem in practical use. That is, when the glass plate is melted with a laser beam, thermal stress is generated in the vicinity of the irradiation region of the laser beam. If this thermal stress is large, the glass plate may be deformed such as warping, or the glass plate may be damaged. Further, when cooling of the melted portion is completed in a state where the thermal stress is generated, thermal residual strain is generated in the melted portion. Even when this thermal residual strain is large, the glass plate may be damaged.

  Therefore, for example, in Patent Document 1, a glass substrate is preheated with a defocused laser beam, a glass plate is melted with a laser beam focused on a minute point, and then gradually defocused with a defocused laser beam. It is disclosed that the thermal strain is reduced by cooling. In the same document, on the planned cutting line of the glass substrate, there are an output end of the laser beam for preheating, an output end of the laser beam for fusing, and an output end of the laser beam for slow cooling (laser irradiator), respectively. The irradiation regions of the respective laser beams are in an independent state with a space between each other.

  In addition, instead of performing slow cooling in parallel with this during the melting as described above, it is possible to individually cool (anneal) the glass plates separated after the completion of the melting. The following problems arise. That is, if thermal stress or thermal residual strain occurs in the glass plate during or after fusing, the glass plate may be damaged at that time. Therefore, it is important to perform slow cooling in parallel with this during melting.

JP-A-60-251138

  However, in Patent Document 1, since the irradiation regions of the three laser irradiators arranged in the upper space of the glass plate are independent from each other, the heat supplied between the irradiation regions is Energy loss can occur. Since it is necessary to make the temperature of the glass plate higher between the irradiation region where the preheating is performed and the irradiation region where the fusing is performed, if the heat energy is lost between the two regions, the preheating effect Will drop and waste. Moreover, since the temperature rise width of the glass plate at the time of fusing will increase when the preliminary heating effect is reduced, the glass plate may be damaged by thermal shock. Furthermore, if the irradiation area | region which performs fusing and the irradiation area | region which performs slow cooling are separated, thermal energy will be lost between these two area | regions, and the glass plate fuse | melted between these two area | regions will be lost. There is also a risk that the glass plate is damaged due to thermal shock due to rapid cooling.

  In view of the above circumstances, the present invention reduces the loss of thermal energy given during preheating before and after fusing and during slow cooling as much as possible, thereby reliably preventing breakage of glass plates and occurrence of thermal residual strain. Controlling is a technical issue.

  The present invention, which was created to solve the above problems, irradiates a laser beam for fusing and a laser beam for slow cooling along the planned cutting line of the glass plate, In the glass cutting method for fusing and separating, in the fusing progress direction along the planned cutting line, the dimension of the irradiation region of the laser beam for slow cooling is made larger than the size of the irradiation region of the laser beam for fusing, and The irradiation region of the laser beam for slow cooling is over the irradiation region of the laser beam for melting so that the irradiation region of the laser beam for slow cooling straddles the front and rear of the irradiation region of the laser beam for melting. Characterized by wrapping. The state of “overlapping” here is a state in which the irradiation region of the slow cooling laser beam and the irradiation region of the fusing laser beam have overlapping portions, and the irradiation region of the slow cooling laser beam is It means that the laser beam for cutting is projected before and after the irradiation direction of the laser beam irradiation region. That is, in the width direction orthogonal to the fusing progress direction, a part of the irradiation region of the fusing laser beam may or may not protrude from the irradiation region of the slow cooling laser beam. . In the former case, for example, when a glass plate is fused and separated into a product part (non-defective product) and a non-product part (non-defective product), the laser beam for cutting out to the non-product part side and the product part side If the laser beam for slow cooling is irradiated, the effect of the present invention can be substantially obtained. In the latter case, the entire irradiation region of the fusing laser beam is included in the irradiation region of the slow cooling laser beam.

  According to such a method, the glass plate is heated at a predetermined temperature equal to or lower than the fusing temperature by the irradiation region of the slow cooling laser beam before and after the fusing progress direction of the fusing laser beam irradiation region. That is, among the irradiation regions of the slow cooling laser beam, annealing is performed in the region on the rear side in the fusing progress direction of the fusing laser beam irradiation region, and the region on the front side in the fusing direction of the fusing laser beam irradiation region. Then, preheating is performed. Therefore, before and after the fusing, it is possible to reduce as much as possible a situation in which breakage due to a sudden temperature rise or a sudden drop in temperature, that is, breakage due to thermal shock or thermal residual strain occurs. And the irradiation area of the laser beam for slow cooling, which plays the role of this preheating and slow cooling, overlaps the irradiation area of the laser beam for fusing, so each area of preheating, fusing and slow cooling is fusing It continues easily and reliably in the direction of travel. Therefore, since a series of these heat treatments is continuously performed on the glass plate, it is possible to suppress the loss of thermal energy to be supplied and efficiently remove the thermal residual strain. The balance between preheating and gradual cooling can be easily adjusted by changing the relative position of the melting laser beam irradiation region with respect to the gradual cooling laser beam irradiation region.

  In the above method, the glass plate is melted and separated into a product part and a non-product part, and the irradiation region of the laser beam for slow cooling is biased toward the product part rather than the non-product part. It is preferable to be formed.

  In this way, when the glass plate is fused and separated into the product part and the non-product part, the preheating process and the slow cooling process can be preferentially performed on the side of the glass plate that becomes the product part. Therefore, it is possible to more reliably reduce the thermal residual strain of the product part.

  In the above method, the irradiation region of the laser beam for slow cooling is more forward of the laser beam for slow cooling in the direction of progress of the laser beam than the center position of the irradiation region of the laser beam for slow cooling in the direction of progress of the melting. It is preferable to overlap the irradiation area.

  If it does in this way, among the irradiation area | regions of the laser beam for slow cooling, the area | region which anneals a glass plate will become longer in the fusing progress direction than the area | region which pre-heats a glass plate. Since the thermal residual strain is generated by being rapidly cooled after fusing, it is preferable to lengthen the region where slow cooling is performed as described above in order to remove the thermal residual strain.

  In the above method, the irradiation region of the slow cooling laser beam may have an elongated shape that is long in the fusing progress direction.

  Thermal residual strain occurs intensively in the vicinity of the fusing part of the glass plate. Therefore, if the irradiation area of the laser beam for slow cooling is elongated in the fusing direction (for example, elliptical shape), fusing The laser beam can be irradiated mainly on the end portion. Therefore, waste of the supplied thermal energy can be reduced as much as possible.

  In the above method, the slow cooling laser beam is preferably irradiated from a direction inclined with respect to the surface of the glass substrate.

  In this way, the irradiation region of the slow cooling laser beam is stretched when projected onto the surface of the glass substrate, so that the irradiation region of the slow cooling laser beam can be easily shaped into an elongated shape. .

  In the above method, it is preferable that the fusing laser beam and the slow cooling laser beam have different wavelengths.

  Since the laser beam is coherent light, it has high coherence. In the present invention, if interference fringes are formed in the overlapping area between the irradiation region of the fusing laser beam and the irradiation region of the slow cooling laser beam, the energy distribution received by the glass plate becomes complicated. As a result, it becomes difficult to sufficiently control each process of fusing and slow cooling. Therefore, in the above method, the fusing laser beam and the slow cooling laser beam are made different in wavelength from each other, thereby suppressing the time-varying interference fringes from being formed in the region where both beams overlap. . Therefore, considering the time average in the overlapping region, the influence of interference fringes can be reduced, and the energy distribution received by the glass plate can be easily controlled sufficiently.

  In the above method, the fusing laser beam and the slow cooling laser beam are preferably beams oscillated by different oscillators.

  In this way, the wavelength of the laser beam for fusing and the wavelength of the laser beam for slow cooling can be easily and stably made different. In other words, if different oscillators are used, for example, even an oscillator that oscillates the same quality laser medium can easily oscillate beams of different wavelengths. Therefore, it is time-consuming to the region where the laser beam for fusing and the laser beam for slow cooling overlap. It is possible to suppress the formation of stationary interference fringes.

  In the above method, the coherence distance between both beams is taken into consideration even when the laser beam oscillated by the same oscillator is used as the fusing laser beam and the slow cooling laser beam. By adjusting the optical path difference between the fusing laser beam and the slow cooling laser beam, the formation of interference fringes can be suppressed.

  According to the present invention as described above, since the irradiation regions for preheating, fusing, and slow cooling are continuous, the loss of heat energy applied during preheating before and after fusing and during slow cooling is minimized. Therefore, it is possible to reliably reduce the rate at which the glass plate breaks due to thermal shock or the thermal residual strain occurs in the glass plate.

(A) is a vertical front view which shows the glass plate cutting device which concerns on this embodiment, (b) is a top view which shows the irradiation area | region of the laser beam. It is a perspective view which shows the irradiation state of the laser beam for slow cooling in the glass plate cutting device which concerns on this embodiment. It is a perspective view which shows the irradiation state of the laser beam for slow cooling in the glass plate cutting device which concerns on this embodiment. (A) is a conceptual diagram for demonstrating the irradiation state at the time of using a parallel beam as a laser beam for slow cooling in the glass plate cutting device concerning this embodiment, (b) is based on this embodiment. It is a conceptual diagram for demonstrating the irradiation state at the time of using a focused beam as a laser beam for slow cooling in a glass plate cutting device, and defocusing the focused beam. (A) is a figure for demonstrating the positional relationship of each irradiation area | region of the laser beam for fusing and the laser beam for slow cooling in the glass plate cutting device which concerns on this embodiment, (b) is the position It is a figure for demonstrating the preferable range of a relationship. It is a perspective view which shows the modification of the irradiation mode of the laser beam which concerns on this embodiment. It is a perspective view which shows the modification of the irradiation aspect of the laser beam in the glass plate cutting device which concerns on this embodiment. It is a vertical front view which shows the modification of the glass substrate used as the cutting object of the glass plate cutting device which concerns on this embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, the glass plate is a glass substrate for a flat panel display having a thickness of 500 μm or less, but it is of course not limited thereto. For example, the present invention can be applied to thin glass sheets in various fields such as solar cells, organic EL, touch panels, and digital signage, and laminates for various uses laminated with organic resins. In addition, it is preferable that the thickness of a glass plate is 300 micrometers or less, especially 200 micrometers or less.

  As shown in FIGS. 1 (a) and 1 (b), a glass sheet cutting apparatus 1 according to an embodiment of the present invention is configured such that a flatly placed glass substrate G is separated from a product portion Ga with a planned cutting line CL as a boundary. The product part Gb is fused and separated, and includes a first laser irradiator 2, a second laser irradiator 3, and a gas injection nozzle 4.

  The first laser irradiator 2 irradiates the cutting laser beam LB1 substantially vertically from above the planned cutting line CL of the glass substrate G. By this fusing laser beam LB1, a first irradiation region SP1 serving as a fusing execution part is formed on a part of the planned cutting line CL of the glass substrate G. In this embodiment, the irradiation region SP1 is cut along the planned cutting line CL by moving the glass substrate G in the transport direction (arrow A in the figure) by transport means (not shown) such as a transport belt that sucks and holds the glass substrate G. The glass substrate G is continuously melted and separated. At this time, a fusing gap S is formed between the fusing end face Ga1 on the side to be the product part Ga and the fusing end face Gb1 on the side to be the non-product part Gb. In addition, not only the case where only the glass substrate G is moved in this way, the processing unit including the first laser irradiator 2, the second laser irradiator 3, and the gas injection nozzle 4 and the glass substrate G are relatively If there is movement, the glass substrate G can be melted. For example, the processing unit may be moved while the glass substrate G is stationary.

  The second laser irradiator 3 irradiates the laser beam LB2 for slow cooling obliquely from the upper side on the side that becomes the non-product part Gb toward the planned cutting line CL. By this slow cooling laser beam LB2, a second irradiation region SP2 serving as a slow cooling execution part is formed in a part of the planned cutting line CL of the glass substrate G. The second irradiation region SP2 is a long and narrow region (for example, an ellipse) along the planned cutting line CL, and the dimension of the second irradiation region SP2 is the fusing progress direction along the planned cutting line CL. (Arrow B in the drawing) is larger than the dimension of the first irradiation region SP1 of the fusing laser beam LB1. And 2nd irradiation area | region SP2 has overlapped with 1st irradiation area | region SP1 so that 2nd irradiation area | region SP2 may straddle before and after the fusing progress direction of 1st irradiation area | region SP1. That is, in a state where the first irradiation region SP1 and the second irradiation region SP2 overlap each other, the second irradiation region SP2 protrudes before and after the fusing progress direction of the first irradiation region SP1. Therefore, when the glass substrate G is heated in the second irradiation region SP2, the glass substrate G is in a region continuous before and after the fusing progress direction of the first irradiation region SP1, and the glass substrate G has a low temperature lower than the fusing temperature (for example, 1300 to 3000 ° C.). (For example, 100 to 1000 ° C.). That is, in the second irradiation region SP2, the glass substrate G is preheated in the region SP2a on the front side in the fusing progress direction of the first irradiation region SP1, and in the region SP2b on the rear side in the fusing direction of the first irradiation region SP1. The glass substrate G is gradually cooled. Then, by moving the glass substrate G as described above, the second irradiation region SP2 is scanned along the planned cutting line CL, and preheating and gradual cooling are continuously performed on the glass substrate G before and after fusing. Applied.

  The gas injection nozzle 4 injects the assist gas AG from above to the first irradiation region SP1 in order to blow away the molten foreign matter generated in the first irradiation region SP1. Specifically, the gas injection nozzle 4 is arranged at an upper position on the side of the glass substrate G that becomes the product part Ga, and the assist gas AG is directed from the upper position on the side that becomes the product part Ga toward the first irradiation region SP1. It is injected at an angle. Thereby, the molten foreign matter is blown off by the assist gas AG to the non-product part Gb side, and the situation where a molten foreign substance adheres to the fusing end surface Ga1 of the product part Ga and a shape defect occurs is suppressed. Here, “molten foreign matter” means foreign matters such as dross generated when the glass substrate G is melted, and includes both those in a molten state and those in a solidified state. As the assist gas AG, for example, a gas such as oxygen (or air), water vapor, carbon dioxide, nitrogen, and argon is used alone or in a mixed state. Further, the assist gas AG may be injected as hot air. The arrangement position of the gas injection nozzle 4 in the upper space of the glass substrate G is not particularly limited. For example, the gas injection nozzle 4 is arranged directly above the planned cutting line CL, and the fusing laser beam is attached to the glass substrate G. The assist gas AG may be injected substantially vertically. Further, the gas injection nozzle 4 may be disposed in the lower space of the glass substrate G so that the molten foreign matter is blown from the lower side of the glass substrate G. These assist gases AG are for efficient fusing, but may be omitted as appropriate.

  In this embodiment, as shown in FIG. 2, the second laser irradiator 3 is arranged at an upper position on the side that becomes the non-product part Gb of the unfinished part R <b> 2. The slow cooling laser beam LB2 emitted from the second laser irradiator 3 is inclined so as to approach the glass substrate G as it moves from the uncut portion R2 side to the blow completed portion R1 side. The slow cooling laser beam LB2 may be inclined so as to approach the glass substrate G as it moves from the fusing completion portion R1 side to the fusing incomplete portion R2 side. That is, the slow cooling laser beam LB2 has an azimuth angle θ and a polar angle φ as shown in the figure. Therefore, as shown in FIG. 3, the second irradiation region SP2 projected on the glass substrate has an elliptical shape. The direction of the major axis of the elliptical shape changes depending on the magnitude of the azimuth angle θ, but has a component of the fusing direction A. Of course, it is also possible to irradiate the second laser beam LB2 in which the cross section orthogonal to the optical axis is shaped into an elliptical shape so that the direction of the major axis is along the fusing progress direction with θ = π / 2. Examples of a method of previously shaping the cross section orthogonal to the optical axis of the laser beam into an elliptical shape include using an optical component such as a cylindrical lens, a slit-shaped light shielding mask, or the like.

Here, the azimuth angle θ and polar angle φ of the slow cooling laser beam LB2 are preferably in the following ranges. That is, the azimuth angle θ is preferably in the range of 0 ≦ θ ≦ π. When a parallel beam is used as the slow cooling laser beam LB2, the irradiation effect is the same in both the range of 0 ≦ θ ≦ π / 2 and π / 2 ≦ θ ≦ π with respect to the azimuth angle θ. There is an appropriate range of azimuth angle θ when using a light beam and irradiating with defocus. That is, when the glass substrate G is defocused at a position below the condensing point, 0 ≦ θ ≦ π / 2 is an appropriate range, and conversely, the glass substrate G is defocused at a position above the condensing point. When irradiated, π / 2 ≦ θ ≦ π is an appropriate range. On the other hand, as shown in FIG. 4A, the polar angle φ preferably satisfies the following range when a parallel beam is used as the slow cooling laser beam LB2. In other words, the polar angle phi is, w ₂ the beam diameter of the slow cooling laser beam LB2, the thickness of the glass substrate G t, when the adjustment amount of the irradiation position is ^{d, 0 <φ <cos -1} [(t + w 2) / {2 (s + t + d)}] is preferably satisfied. Further, as shown in FIG. 4B, the polar angle φ satisfies the following range when a focused beam is adopted as the slow cooling laser beam LB2 and is defocused and irradiated. It is preferable to do. That is, the polar angle φ is the beam diameter w ₂ at the contact point in the state where the slow cooling laser beam LB2 is in contact with the non-product part Gb, the condensing angle α, the thickness of the glass substrate G, and the irradiation position. When the adjustment amount is d, it is preferable to satisfy the range of 0 <φ <cos ⁻¹ [(tcos α + w ₂ ) / {2 (s + t + d)}]. In other words, the polar angle φ is preferably set in an angle range that does not interfere with the vicinity of the fusing end face Gb1 of the non-product part Gb that is close to and faces the fusing end face Ga1 of the product part Ga. The irradiation position of the slow cooling laser beam LB2 is preferably adjusted according to the position of the tensile stress generated in the vicinity of the melt end face Ga1 of the product part Ga before the slow cooling, and the adjustment amount d is, for example, −0. Adjustment is made within the range of 5t ≦ d ≦ 2.5t.

  If the laser beam LB2 for slow cooling is shaped so that the cross section orthogonal to the optical axis is elliptical, the second irradiation region having a long overall length without increasing the inclination angle (polar angle φ). SP2 can be formed.

  Next, operation | movement of the glass cutting device 1 which concerns on this embodiment comprised as mentioned above is demonstrated.

  First, as shown in FIGS. 1A and 1B, the glass substrate G is irradiated with a laser beam LB1 for fusing from the first laser irradiator 2 while the glass substrate G is being conveyed. Thereby, the glass substrate G is melted. The assist gas AG is injected from the gas injection nozzle 4 into the first irradiation region SP1 of the fusing laser beam LB1, and the molten foreign matter is blown off from the first irradiation region SP1.

  At the same time, the glass substrate G is irradiated with the laser beam LB2 for slow cooling from the second laser irradiator 3. The second irradiation region SP2 of the slow cooling laser beam LB2 overlaps the first irradiation region SP1 so as to straddle the fusing progress direction of the first irradiation region SP1 of the fusing laser beam LB1. Due to this overlap, preheating is performed in the region SP2a on the front side in the fusing progress direction of the first irradiation region SP1 in the second irradiation region SP2, and slow cooling is performed in the region SP2b on the rear side in the fusing progress direction. Is done. Therefore, before and after the fusing, it is possible to reduce as much as possible a situation in which breakage due to a rapid temperature rise or drop, that is, breakage due to thermal shock or thermal residual strain occurs. In particular, in the case of a glass substrate of 500 μm or less, if the preheating / melting / slow cooling regions SP2a, SP1, and SP2b are separated from each other, the temperature rises and falls rapidly. And since 2nd irradiation area | region SP2 which plays the role of this preheating and slow cooling overlaps 1st irradiation area | region SP1, each area | region SP2a, SP1, SP2b of preheating, fusing, and slow cooling is fusing. It continues easily and reliably in the direction of travel. Therefore, it is possible to avoid a situation in which the series of heat treatments are continuously performed on the glass substrate G and the heat energy is unreasonably lost between the heat treatment regions SP2a, SP1, and SP2b. In other words, it is possible to remove the thermal residual strain while efficiently performing preheating and fusing with the thermal energy supplied to the glass substrate G.

Here, as shown to Fig.5 (a), the line which passes along the center position of the direction orthogonal to the fusing progress direction of 2nd irradiation area | region SP2 and extends in a fusing progress direction is set to X axis, This X axis and 2nd irradiation area | region Y-axis a line perpendicular at the center of the blowout direction of travel of SP2, and is X-axis dimension of the second irradiation region SP2 2a2, 2b ₂ a Y-axis dimension of the second irradiation region SP2, X of the first irradiation region SP1 When the dimension in the axial direction is 2a ₁ , the dimension in the Y-axis direction of the first irradiation area SP1 is 2b ₁ , and the center coordinates of the first irradiation area SP1 are (x, y), the first irradiation area SP1 and the second irradiation area The preferred relationship with SP2 is as follows.

That is, the relationship between the spot diameters of the first irradiation region SP1 and the second irradiation region SP2 is a ₁ <a ₂ and b ₁ <b ₂ .
50a ₁ ≦ a ₂
30b ₁ ≦ b ₂ (1)
It is preferable that The center coordinates (x, y) of the first irradiation region SP1 are
_{-A 2/4 ≦ x <a} 2 -a 1
_{-B 2 -b 1 <y ≦ b} 2/2 ··· (2)
It is preferable to satisfy the following relationship (region indicated by A1 in FIG. 5B),
_{a 2/4 ≦ x ≦ 3a} 2/4
_{-B 2/2 ≦ y ≦ 0} ··· (3)
It is more preferable to satisfy the relationship (region indicated by A2 in FIG. 5B).

If the above (1) or (2) is satisfied, the size relationship and the positional relationship between the first irradiation region SP1 and the second irradiation region SP2 become optimal, and the thermal residual strain in the product portion Ga of the glass substrate G Can be reliably reduced. If (3) is satisfied, the second irradiation region SP2 is formed more biased toward the product portion Ga side than the non-product portion Gb side, and the center position (Y in the fusing progress direction of the second irradiation region SP2) The first irradiation region SP1 overlaps the second irradiation region SP2 on the front side of the axis position). In this way, since the preheating process and the slow cooling process can be preferentially performed on the side of the glass substrate G that becomes the product part Ga, the thermal residual strain of the product part Ga is more reliably ensured. It becomes possible to reduce it. Further, in this case, in the irradiation region SP2, the dimension in the fusing progress direction of the region SP2b where the slow cooling is performed becomes longer than the dimension in the fusing progress direction of the region SP2a where the preheating is performed. Since thermal residual strain is caused by rapid cooling after fusing, it is preferable to lengthen the region for slow cooling and reduce the cooling rate as described above in order to remove the thermal residual strain. It becomes.

  Further, it is preferable that the fusing laser beam and the slow cooling laser beam have different wavelengths from each other by using beams oscillated by different oscillators. In this way, a steady interference fringe is not temporally formed by the fusing laser beam and the slow cooling laser beam, and it becomes easy to sufficiently control the energy distribution given to the glass plate.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible.

  In said embodiment, the case where the 1st laser irradiation device 2 is arrange | positioned just above the cutting projected line CL of the glass substrate G, and the 2nd laser irradiation device 3 is arrange | positioned above the non-product part Gb of the glass substrate G is used. Although demonstrated, the arrangement | positioning aspect of the 1st laser irradiation device 2 or the 2nd laser irradiation device 3 is not limited to this. For example, as shown in FIG. 6, the first laser irradiator 2 and the second laser irradiator 3 are arranged above the product portion Ga, and the laser beam LB1 for fusing is formed by optical components such as mirrors 5 and 6. Further, the slow cooling laser beam LB2 may be guided.

  In the above embodiment, the first laser irradiator 2 and the second laser irradiator 3 are configured by separate light sources. However, as shown in FIG. 7, the first laser irradiator 2 is a second laser. The irradiator 3 may also be used. In other words, the laser beam LB emitted from the first laser irradiator 2 may be branched into the fusing laser beam LB1 and the slow cooling laser beam LB2 by an optical component such as the half mirror 7. In this case, the laser beam LB2 for slow cooling is adjusted for the glass substrate G after adjusting the energy by adjusting the transmittance (reflectance) of the half mirror or the like, or by dimming with an ND filter or the like on the optical path. May be irradiated. Further, in consideration of the coherence distance between the fusing laser beam LB1 and the slow cooling laser beam LB2, the optical path difference between the two beams may be adjusted to suppress the formation of interference fringes.

  Further, when the glass substrate G is formed by an overflow down draw method or the like, the thickness of both end portions in the width direction of the glass substrate G is relatively larger than the thickness of the center portion in the width direction of the glass substrate G as shown in FIG. It becomes thick. And the width direction center part is made into the product part Ga, and the width direction both ends are made into the non-product part (it calls an ear | edge part) Gb. The cutting method and the cutting apparatus according to the present invention may be applied to the removal of the ear portion of the glass substrate G.

  In the above-described embodiment, the case where the glass substrate G is fused and separated into the product part Ga and the non-product part Gb has been described. However, the glass substrate G may be applied to the case where both of the fused parts are used as the product part.

Examples of the present invention will be described. In this example, fusing is performed by scanning a laser beam for fusing (a CO ₂ laser having a wavelength of around 10.6 μm, indicated as output 1 in the following table) at a relative movement speed of 10 mm / s. When the residual strain at the time of performing was set to 10, it was examined how much this residual strain was improved. If the residual strain is 10, the glass substrate may be deformed such as warping, or may be damaged during handling or processing. The residual strain is preferably 3 or less. In addition to the above-described residual strain inspection, it was also inspected whether the glass substrate was damaged by thermal shock at the time of fusing. It is considered that damage due to thermal shock can occur when the glass substrate is heated suddenly during fusing.

Specifically, each of the irradiation regions of the fusing laser beam and the slow cooling laser beam (CO ₂ laser near the wavelength of 10.6 μm, indicated as output 2 in the table below) oscillated by different oscillators. The degree of improvement of the residual strain and the damage caused by thermal shock was evaluated by changing the relative position or changing the size of the irradiation region of the slow cooling laser beam. The results are shown in Tables 1-3. Incidentally, a ₁ in the table shown _{below, b 1, a 2, b} 2, x, the sign of y shall conform in Figure 5 (b). Also, output 1 and output 2 in the table below represent the energy of each laser beam on the glass substrate surface.

According to Table 1 above, sample No. In No. 1, since pre-heating and gradual cooling were not applied to the thin glass, the residual strain was 10 and cracking due to thermal shock occurred. On the other hand, sample No. which is an example. In Nos. 2 to 9, since the second irradiation region (irradiation region of the slow cooling laser beam) overlaps before and after the first irradiation region (irradiation region of the fusing laser beam), the thin glass is blown out. Since preheating and gradual cooling were performed before and after, residual strain was improved, and cracking due to thermal shock did not occur. In particular, sample no. As in the case of ₂ , 7 to 9, in the range where a ₂ / a ₁ ≧ 50 and b ₂ / b ₁ ≧ 30, extremely good results with a residual strain of 1 were obtained.

  According to Table 2 above, sample No. In No. 10, since the second irradiation region protrudes only to the front side in the fusing progress direction of the first irradiation region, the thin glass is not slowly cooled after fusing, and the residual strain is improved. There wasn't. In addition, sample No. In No. 20, since the second irradiation region is in a state of protruding only to the rear side in the fusing progress direction of the first irradiation region, the thin glass is not preheated before fusing and cracking due to thermal shock occurs. It came to. On the other hand, sample No. which is an example. In Nos. 11 to 19, since the second irradiation region is protruding before and after the fusing progress direction with the first irradiation region overlapping, preheating and gradual cooling are performed before and after fusing the thin glass. As a result, the residual strain was improved, and cracking due to thermal shock was also improved.

  According to Table 3 above, sample No. which is a comparative example. 21, the second irradiation region is not overlapped with the first irradiation region and is shifted to the product portion side of the thin glass, so that the heat energy from the second irradiation region does not act on the first irradiation region and remains. The results showed that neither distortion nor cracking due to thermal shock was improved. In addition, sample No. In 31, the second irradiation region does not overlap with the first irradiation region and is shifted to the non-product part side of the thin glass, so that the thermal energy by the second irradiation region does not act on the first irradiation region, Similarly, the results showed that neither residual strain nor cracking due to thermal shock was improved. On the other hand, sample No. which is an example. In 22-30, since it has an overlap part in the width direction orthogonal to a fusing progress direction in the state where the 2nd irradiation area was protruding before and after the fusing progress direction of the 1st irradiation area, it is in the fusing part of sheet glass. The effects of preheating and gradual cooling acted, the residual strain was improved, and no cracking due to thermal shock occurred.

In particular, according to Tables 2 and 3, sample no. 12-19 and Sample No. As _{22~30, -a 2/4 ≦ x} <a 2 -a 1, and, in the range of a _{-b 2 -b 1 <y ≦ b} 2/2, remain with the cracked due to thermal shock is improved It can be confirmed that an excellent result that the strain is 3 or less is obtained. Among these, sample no. 15-17 and sample no. In the range of 1/4 ≦ x / a ₂ ≦ 3/4 and −1 / 2 ≦ y / b ₂ ≦ 0 as in 25 to 26, there is no cracking due to thermal shock, and the residual strain is 1 It can be confirmed that extremely good results are obtained as follows.

DESCRIPTION OF SYMBOLS 1 Glass plate cutting device 2 1st laser irradiator 3 2nd laser irradiator 4 Gas injection nozzle AG Assist gas CL Planned cutting line G Glass substrate Ga Product part Ga1 Fusing end surface Gb Non-product part LB1 Fusing laser beam LB2 For slow cooling Laser beam SP1 first irradiation area (melting execution part)
SP2 Second irradiation region SP2a Preheating region SP2b Slow cooling region S Fusing gap R1 Fusing completion portion R2 Fusing incomplete portion θ Azimuth angle of slow cooling laser beam φ Polar angle of slow cooling laser beam

Claims (7)

In the glass plate cutting method of irradiating the laser beam for fusing and laser beam for slow cooling along the planned cutting line of the glass plate, and cutting and separating the glass plate with the planned cutting line as a boundary,
In the fusing progress direction along the planned cutting line, the dimension of the irradiation region of the laser beam for slow cooling is larger than the size of the irradiation region of the laser beam for fusing, and
The irradiation region of the slow cooling laser beam is changed to the irradiation region of the laser beam for fusing so that the irradiation region of the laser beam for slow cooling straddles the front and rear of the irradiation region of the laser beam for fusing in the fusing progress direction. A glass plate cutting method characterized by being overlapped.   The glass plate is fused and separated into a product part and a non-product part, and the irradiation region of the laser beam for slow cooling is formed so as to be biased toward the product part side rather than the non-product part side. The glass plate cutting method according to claim 1, wherein:   The irradiation region of the laser beam for fusing overlaps with the irradiation region of the laser beam for slow cooling on the front side in the fusing direction with respect to the center position of the irradiation region of the laser beam for slow cooling in the direction of fusing progression. The glass plate cutting method according to claim 1 or 2, wherein:   The glass plate cutting method according to any one of claims 1 to 3, wherein an irradiation region of the slow cooling laser beam has a long and narrow shape in the fusing direction.   The glass plate cutting method according to claim 4, wherein the slow cooling laser beam is irradiated from a direction inclined with respect to a surface of the glass substrate.   The glass sheet cutting method according to any one of claims 1 to 5, wherein the fusing laser beam and the slow cooling laser beam have different wavelengths.   The glass sheet cutting method according to claim 6, wherein the fusing laser beam and the slow cooling laser beam are beams oscillated by different oscillators.

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