CN114929636A

CN114929636A - Method for manufacturing glass plate

Info

Publication number: CN114929636A
Application number: CN202080092088.8A
Authority: CN
Inventors: 松伏泰生; 中岛将雄; 泷本博司
Original assignee: Nippon Electric Glass Co Ltd
Current assignee: Nippon Electric Glass Co Ltd
Priority date: 2020-01-08
Filing date: 2020-12-04
Publication date: 2022-08-19
Also published as: JP7421162B2; WO2021140801A1; KR20220124680A; TW202136164A; JP2021109788A

Abstract

When forming a scribe line (11) along a line (4) to cut including a closed curve (4R) on the front surface (Gh) of a mother glass (G), assuming that the closed curve (4R) is formed of a plurality of unit closed curves (4R1, 4R2) and assuming that the line (4) to cut is formed of a plurality of unit lines to cut (4A, 4B) each including a plurality of unit closed curves (4R1, 4R2), unit concave lines (6A, 6B) caused by plastic deformation are formed for each of the plurality of unit lines to cut (4A, 4B), and a scribe line (11) formed by connecting a plurality of unit scribe lines (11A, 11B) continuously is formed by extending a plurality of initial cracks (10, 12) along the unit concave lines (6A, 6B).

Description

Method for manufacturing glass plate

Technical Field

The present invention relates to a manufacturing technique for separating a glass plate having an outer contour shape corresponding to a closed curve from a mother glass having a line to cut including the closed curve on a surface thereof.

Background

In the field of glass plate production, there is known a technique for producing a glass plate by forming a scribe line having a closed curve on a surface of a mother glass and separating a product having an outer contour shape corresponding to the closed curve or a product material from the mother glass.

As a specific example thereof, a method for producing a glass plate disclosed in patent document 1 can be mentioned. In this manufacturing method, first, a scribe line for outline that is a closed curve and an auxiliary scribe line that approaches the scribe line for outline from the outside are formed on mother glass (a brittle material substrate in this publication). Next, after the crack is stretched along the auxiliary scribe line, the crack is stretched along the outline-use scribe line from the auxiliary scribe line, and the glass plate (product substrate in this publication) is separated from the mother glass.

Here, the outline scribing line disclosed in patent document 1 is understood to be a narrow groove-like line cut into the surface of the mother glass by a scribing wheel, a scribing cutter, or the like (see paragraphs 0015 and 0016 and the like of japanese patent No. 5171522 cited in patent document 1 and claim 2 and the like of japanese patent application laid-open No. 2014-217982 and the like cited in patent document 2). When the outline scribe line is formed by this method, a crack (transverse crack) extending in a direction parallel to the surface of the mother glass is formed at the edge of the scribe line. This transverse crack remains in the glass sheet after separation from the mother glass, and therefore becomes an important factor for reducing the mechanical strength of the glass sheet. Therefore, chamfering or the like for removing the transverse crack is required for the end face of the glass sheet, which leads to an increase in man-hours required for manufacturing the glass sheet and an increase in time.

As a manufacturing technique for coping with such a problem, a method for manufacturing a glass plate disclosed in patent document 2 can be mentioned. The manufacturing method comprises the following steps: forming a concave line caused by plastic deformation on the surface of the mother glass by using a scribing head; forming an initial crack at a position corresponding to the recessed line; and a step of extending the initial crack along the concave line. The scribe line (in this publication, the crack C) capable of extending the initial crack is formed not as a closed curve but as a straight line. According to this manufacturing method, the surface of the mother glass is plastically deformed by pressing with the scribe head, so that the concave line having no lateral crack can be formed. This makes it possible to obtain a state in which no transverse crack is present at the end face of the glass sheet separated from the mother glass.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2019-43010

Patent document 2: japanese patent laid-open publication No. 2019-89672

Disclosure of Invention

Problems to be solved by the invention

However, when the method of forming a concave line due to plastic deformation as disclosed in patent document 2 is applied to the method of forming a scribe line having a closed curve as disclosed in patent document 1, the following problems occur.

That is, if the shape of the line to cut having a closed curve includes a long curved line portion or includes a straight line portion and a curved line portion repeatedly, the crack may stop extending in the middle of the concave line. When such a situation occurs, mother glass has to be discarded, which may lead to deterioration in product yield and reduction in production efficiency.

From the above-described viewpoint, an object of the present invention is to suppress the occurrence of a lateral crack and smoothly extend an initial crack over the entire length of a concave line caused by plastic deformation in a scribing step for forming a scribe line including a closed curve on the surface of a mother glass.

Means for solving the problems

The present invention made to solve the above problems is a method for manufacturing a glass plate, comprising: a preparation step of preparing a mother glass and a scribe head for forming a concave line caused by plastic deformation on a surface of the mother glass by moving while pressing the surface of the mother glass; a scribing step of forming a scribing line along a line to cut including a closed curve on the surface of the mother glass; and a breaking step of breaking the mother glass along the scribe line to separate the glass plate having an outer contour shape corresponding to the closed curve from the mother glass, in the scribing step, the closed curve is assumed to be composed of a plurality of unit closed curves continuously connected to each other on the surface of the mother glass, and assuming that the line to cut is constituted by a plurality of lines to cut including the plurality of unit closed curves, respectively, the scribing head is moved while being pressed along the plurality of lines to cut respectively, thereby forming unit recessed lines caused by plastic deformation for each of the plurality of unit lines, then, initial cracks corresponding to the unit concave lines are formed, and the initial cracks are extended along the unit concave lines, thereby forming the scribe line in which a plurality of unit scribe lines are continuously connected.

According to this configuration, in the scribing step, it is assumed that the line to cut including the closed curve is formed of a plurality of lines to cut unit including a plurality of unit closed curves, and a unit recessed line due to plastic deformation is formed for each of the plurality of lines to cut unit. This makes it difficult to cause a lateral crack on the surface of the mother glass. Then, a plurality of initial cracks are respectively propagated along the unit concave lines, thereby forming scribe lines. Therefore, when forming the scribe line along the closed curve, one initial crack only needs to extend by a distance shorter than the entire length of the concave line formed along the line to cut. This makes it difficult to cause a defect that the initial crack is stretched halfway in the concave line, and reduces the amount of waste mother glass, thereby improving the product yield and the production efficiency.

In this manufacturing method, the plurality of lines to cut unit may be two lines to cut unit.

As a result of the plurality of lines to cut being two lines to cut, the plurality of unit closed curves become two unit closed curves, the plurality of unit concave lines due to plastic deformation become two unit concave lines due to plastic deformation, the plurality of initial cracks become two initial cracks, and the plurality of unit scribe lines become two unit scribe lines. In this way, the distance by which each initial crack extends along the concave line can be halved.

In the above manufacturing method, in the scribing step, the unit closed curve may have a straight line portion and a curved line portion.

In this way, a special effect is obtained by setting the closed curve to a plurality of unit closed curves. That is, since the initial crack is hard to extend at a portion where the concave line is curved, when the closed curve has a curved line portion at a plurality of portions, the probability that the extension of the initial crack is stopped becomes high. In contrast, if the closed curve is formed of a plurality of unit closed curves as in the configuration of the present invention, the number of curved line portions existing in each unit closed curve can be reduced, and the probability of extension stop of the initial crack can be reduced.

In the above manufacturing method, in the scribing step, each of the plurality of lines to cut unit may be constituted by the unit closed curve and a unit extension line extending from one end of the unit closed curve to an outer side of the closed curve.

In this way, since each of the plurality of planned unit cutting lines includes not only the unit closed curve but also the unit extended line, each of the unit recessed lines formed along the planned unit cutting lines includes each of the recessed line portions corresponding to each of the unit extended lines. Therefore, when the initial cracks are formed in the respective recessed line portions corresponding to the unit extension lines, the initial cracks can be extended along the respective unit recessed lines. This facilitates the operation of forming a plurality of initial cracks.

In the manufacturing method, in the scribing step, one unit closed curve among the plurality of unit closed curves and another unit closed curve adjacent to the one unit closed curve may have a straight line portion and a curved line portion continuous to the straight line portion, respectively, and a unit extension line extending from one end of the one unit closed curve may extend along the same straight line as the straight line portion of the one unit closed curve and may extend along a tangent line of the curved line portion of the another unit closed curve.

In this way, the unit extension line extending from one end of the one unit closed curve is connected to the straight line portion of the one unit closed curve on a straight line, and thus the initial crack can be smoothly extended along the concave line formed on the straight line. Further, since the unit extension line extending from one end of one unit closed curve extends along a tangent line of the curved line portion of the other unit closed curve adjacent thereto, a continuous portion where the unit scribing line formed along one unit closed curve and the unit scribing line formed along the other unit closed curve are connected is smoothly formed. Therefore, when the connecting portion of the two unit scribe lines is not smoothly formed, a defect or the like may occur in the connecting portion, but such a defect is not easily caused by the structure herein.

In these manufacturing methods, in the scribing step, the unit extension line may reach an edge of the mother glass.

In this way, when the scribe head forms the recessed lines along the unit extension lines, it is advantageous to form the recessed lines from the central region of the mother glass toward the end edges. That is, in this case, when the scribe head passes the edge of the mother glass, the edge can be notched (e.g., scratched, chipped, or the like) by the scribe head to form an initial crack. Therefore, it is not necessary to separately form the initial crack using another cutter or the like, and the operation of forming the scribing line is simplified.

Effects of the invention

According to the present invention, in the scribing step for forming the scribe line including the closed curve on the surface of the mother glass, the initial crack can be smoothly extended over the entire length of the concave line due to the plastic deformation while suppressing the occurrence of the lateral crack.

Drawings

Fig. 1 is a process diagram showing steps of a method for manufacturing a glass plate according to an embodiment of the present invention.

Fig. 2 is a perspective view showing a mother glass used in the method for producing a glass plate according to the embodiment of the present invention.

Fig. 3 is a perspective view showing a main part of a scribing head used in the method for manufacturing a glass plate according to the embodiment of the present invention.

Fig. 4 is a schematic side view showing the operation of the scribing head used in the method for manufacturing a glass plate according to the embodiment of the present invention.

Fig. 5 is a vertical cross-sectional front view showing a concave line formed on the surface of mother glass by the method for manufacturing a glass sheet according to the embodiment of the present invention.

Fig. 6 is a vertical cross-sectional front view showing another example of a main part of a scribing head used in the method for manufacturing a glass plate according to the embodiment of the present invention and another example of a concave line formed on a surface of a mother glass by the manufacturing method.

Fig. 7 is a plan view for explaining lines to cut on the surface of mother glass used in the method for producing a glass sheet according to the embodiment of the present invention.

Fig. 8 is a plan view showing a process of forming a scribing line on mother glass by the manufacturing method of a glass plate of the embodiment of the present invention.

Fig. 9 is a longitudinal sectional front view showing a state where an initial crack is formed in mother glass by the method for manufacturing a glass sheet according to the embodiment of the present invention.

Fig. 10 is a perspective view showing a process of initial crack propagation formed in mother glass by the method for manufacturing a glass sheet according to the embodiment of the present invention.

Fig. 11 is a plan view showing a state where a scribe line is formed in mother glass by the method for manufacturing a glass plate according to the embodiment of the present invention.

Fig. 12 is a plan view showing a state where a scribe line is formed in mother glass by a first modification of the method of manufacturing a glass plate according to the embodiment of the present invention.

Fig. 13 is a plan view showing a state where a scribe line is formed in mother glass by a second modification of the method of manufacturing a glass plate according to the embodiment of the present invention.

Fig. 14 is a plan view showing a state where a scribe line is formed in mother glass by a third modification of the method of manufacturing a glass plate according to the embodiment of the present invention.

Fig. 15a is a plan view showing a process of breaking the mother glass by the method of manufacturing a glass sheet according to the embodiment of the present invention.

Fig. 15b is a cross-sectional view taken along line Z-Z of fig. 15 a.

Fig. 16a is an enlarged longitudinal sectional front view showing a process of breaking a mother glass by the method for manufacturing a glass sheet according to the embodiment of the present invention.

Fig. 16b is an enlarged vertical cross-sectional front view showing a state where the mother glass is broken by the method for manufacturing a glass sheet according to the embodiment of the present invention.

Detailed Description

Hereinafter, a method for manufacturing a glass plate according to an embodiment of the present invention will be described with reference to the drawings.

As shown in fig. 1, the method for manufacturing a glass sheet includes: a preparation step 1 of preparing mother glass and a scribing head; a scribing step 2 of forming a scribing line along a line to cut the surface of the mother glass; and a breaking step 3 of separating the glass plate from the mother glass by breaking the mother glass along the scribe line.

Fig. 2 illustrates the mother glass G prepared in the preparation step 1. The mother glass G has a rectangular shape, and the line 4 to cut Gh on the surface Gh thereof includes a closed curve 4R. The size of the mother glass G is not particularly limited, but it is preferable that the length of one side is 50mm or more, and the thickness t is preferably 0.01mm to 1mm, more preferably 0.01mm to 0.7 mm.

Fig. 3 and 4 illustrate the scribing head 5 prepared in the preparation step 1. The scribing head 5 is a pen type, and has a shank 5a and a head 5b fixed to an end of the shank 5 a. The holder 5c holding the holder 5a moves the scribing head 5 in the vertical direction and the horizontal direction. Further, the holder 5c can freely change the inclination angle of the holder 5a with respect to the mother glass G.

The head 5b is preferably made of, for example, single crystal or polycrystalline diamond, but may be made of PCBN, ceramic, cemented carbide, or other metal. The head 5b has a truncated cone shape with a planar end face 5d, and a pressing portion 5e that is in contact with the mother glass G and has an arc shape in plan view is formed at an end portion of the head 5 b. Specifically, the pressing portion 5e is an edge of an end surface 5d at the axial end of the head 5 b. In this case, the scribe head 5 moves in a state of being inclined with respect to the surface Gh of the mother glass G (the inclination angle is, for example, 30 ° to 85 °). When moving in this inclined state, the pressing portion 5e (the edge of the end face 5 d) moves in the arrow X direction while pressing the surface Gh of the mother glass G, and plastic deformation occurs in the surface Gh, and a concave line 6 is formed in the plastic deformation portion. The radius (curvature radius) of the pressing portion 5e is preferably 0.001mm to 1mm, and more preferably 0.025mm to 0.5 mm.

Fig. 5 is a view showing a state around the concave line 6 having a curved cross section (a cross section perpendicular to a direction in which the concave line 6 extends). As shown in the figure, the depth D1 of the concave line 6 is, for example, 300nm to 500nm, and the width W1 of the concave line 6 is, for example, 15 μm to 30 μm. A compressive stress layer 7 caused by plastic deformation is formed inside the concave line 6, and a tensile stress layer 8 is formed in an inner region inside the compressive stress layer 7. Further, at the end in the width direction of the concave line 6, a protrusion 9 protruding from the surface Gh is formed by plastic deformation over the entire length of the concave line 6. The protrusion amount h of the protrusion 9 from the surface Gh is, for example, 10nm to 20 nm.

In this case, as the scribing head 5, as shown in fig. 6, a scribing head having a V-shaped head 5b at the tip of the shank 5a and the tip of the head 5b serving as the pressing portion 5e can be used. The manner of using the scoring head 5 is substantially the same as that shown in fig. 4. When this scribe head 5 is used, as shown in fig. 6, concave lines 9 having a V-shaped cross section are formed on the surface Gh of the mother glass G, and a vertically long tensile stress layer 8 is formed inside the concave lines 6. In the following description, for convenience, the case where the scribing head 5 shown in fig. 3 described above is used is taken as an example.

Fig. 7 is a plan view illustrating a surface Gh of the mother glass G used when the scribing process 2 is performed. As shown in the figure, the line 4 to cut the front surface Gh of the mother glass G includes a closed curve 4R in which four corners of a rectangle are curved in an arc shape. It is assumed that the lines 4 include first lines 4A indicated by thick chain lines and second lines 4B indicated by thin chain lines. It is assumed that the closed curve 4R is constituted by a first unit closed curve 4R1 for the first line 4A and a second unit closed curve 4R2 for the second line 4B. It is assumed that the first unit closed curve 4R1 is composed of two straight line portions 4a1, 4a2 and two curved line portions 4a1, 4a 2. It is assumed that the second unit closed curve 4R2 is composed of two straight line portions 4B1, 4B2 and two curved line portions 4B1, 4B 2. The first line 4A is assumed to have a first unit extension line 4A3 extending outward from the first unit closed curve 4R1 toward one end of the closed curve 4R. The second line 4B is assumed to have a second unit extension line 4B3 extending from one end of the second unit closed curve 4R2 to the outside of the closed curve 4R. In this case, the first unit extension line 4A3 extends from one end of the straight portion 4a1 (the upper end of the paper surface) along the same straight line as the straight portion 4a1 and reaches the end edge (the upper end of the paper surface) Gx of the mother glass G. The second unit extension line 4B3 extends from one end of the straight portion 4B1 (the end on the lower side of the paper surface) along the same straight line as the straight portion 4B1 and reaches the end edge Gy of the mother glass G (the end edge on the lower side of the paper surface).

In the scribing step 2, first, as shown in fig. 8, the first unit concave lines 6A are formed by plastic deformation by moving the scribing head 5 along the first unit planned cutting lines 4A while pressing them. More specifically, the scribe head 5 moves in the direction indicated by the arrow a from the start point 4Ax of the first line 4A (one end of the curved line portion 4A 2) over the curved line portion 4A2, the straight line portion 4A2, the curved line portion 4A1, the straight line portion 4A1, and the first unit extension line 4A3, and reaches the end point 4Ay of the first line 4A (one end of the first unit extension line 4A 3). As a result, the first unit concave line 6A having the cross section as shown in fig. 5 described above is formed. In this case, the scribe head 5 makes a cut (flaw, defect, or the like) to the end edge Gx of the mother glass G at the end point 6Ay of the first unit concave line 6A, and a first initial crack 10 is formed in the tensile stress layer 8 at the end point 6Ay of the first unit concave line 6A as shown in fig. 9. As time passes thereafter, the first initial crack 10 is propagated along the first unit concave line 6A by the tensile stress of the tensile stress layer 8, thereby forming a first unit scribe line 11A along the entire length of the first unit concave line 6. The first initial crack 10 starts from the end point 6Ay of the first unit concave line 6A as shown by an arrow Y in fig. 10 and finishes from the start point 6Ax of the first unit concave line 6A as shown in fig. 8. The first unit scribe line 11A is formed by extending the first initial crack 10 in the tensile stressor layer 8. Therefore, the first unit scribe line 11A does not reach the surface Gh of the mother glass G (the surface of the concave line 6A) due to the presence of the compressive stress layer 7. The first unit scribe line 11A may reach the surface Gh of the mother glass G by reducing the pressing force of the scribe head 5 and reducing the thickness of the compressive stress layer 7 (the same applies to a second unit scribe line 11B described later).

Next, in the scribing step 2, as in the above case, as shown in fig. 11, the second unit recessed lines 6B are formed along the entire length thereof By plastic deformation from the start point 4Bx toward the end point 4By of the second line 4B to be cut By using the scribing head 5. In detail, the second unit concave line 6B is formed by moving the scribe head 5 in the direction indicated by the arrow B above the bent line portion 4B2, the straight line portion 4B2, the bent line portion 4B1, the straight line portion 4B1, and the second unit extension line 4B 3. Thereafter, a second initial crack 12 as shown in fig. 9 is formed at the end point 6By of the second unit concave line 6B, and then the initial crack 12 is extended from the end point 6By of the second unit concave line 6B toward the start point 6Bx (see fig. 10), thereby forming a second unit scribe line 11B along the entire length of the second unit concave line 6B as shown in fig. 11. As a result, the scribe line 11 in which the first unit scribe line 11A and the second unit scribe line 11B are continuously connected, that is, the scribe line 11 along the entire length of the line 4 to cut including the closed curve 4R is formed in the mother glass G.

In the scribing step 2 described here, the second unit concave line 6B is formed after the first unit concave line 6A is formed, but the timings of forming the two unit

concave lines

6A and 6B may overlap as long as the second initial crack 12 starts to propagate after the first initial crack 10 has completed. The scribing head 5 for forming the two unit

concave lines

6A and 6B may be used as the same scribing head or may be a separate scribing head.

According to the scribing step 2 as described above, the following operational effects are obtained. That is, since the first unit concave lines 6A and the second unit concave lines 6B are formed by plastic deformation by pressing, the transverse cracks are less likely to occur on the surface Gh of the mother glass G. Since the two

initial cracks

10 and 12 extend along the two unit

concave lines

6A and 6B, respectively, the two

initial cracks

10 and 12 may extend at half the total length of the two unit

concave lines

6A and 6B for forming the scribe line 11 along the line 4. This makes it difficult for a disadvantage that may occur when one initial crack is stretched over the entire length of the concave line obtained by combining the two unit

concave lines

6A and 6B, that is, an disadvantage that the initial crack is stretched halfway in the concave line to stop. As a result, the amount of mother glass G discarded is reduced, and the yield and production efficiency are improved.

In addition, since the initial crack is particularly unlikely to propagate in the bend line segment in the closed curve 4R of the line 4, if the four bend line segments 4a1, 4a2, 4b1, and 4b2 are stretched for one initial crack as in the above example, the probability of the initial crack being halted increases. However, in the scribing step 2, only two bending lines need to be partially extended for one initial crack, and therefore, the probability of the extension of the initial crack being stopped can be reduced.

In the scribing step 2, the straight portion 4a1 of the first unit closed curve 4R1 and the first unit extension line 4A3 are connected to each other on a straight line, and the straight portion 4B1 of the second unit closed curve 4R2 and the second unit extension line 4B3 are connected to each other on a straight line, so that the

initial cracks

10 and 12 can be smoothly extended along the concave portions formed at the connected portions. Further, since the first unit extension line 4a3 extends along a tangent to the curved line segment 4B2 of the second unit closed curve line 4R2 and the second unit extension line 4B3 extends along a tangent to the curved line segment 4a2 of the first unit closed curve line 4R1, a continuous portion of the two

unit scribing lines

11A and 11B can be smoothly formed. Therefore, when the connecting portion between the two

unit scribe lines

11A and 11B is not smoothly formed, a defect or the like may occur in the connecting portion, but such a defect is not easily caused in the scribing step 2 here.

In the scribing step 2, since the two unit extension lines 4a3, 4B3 reach the end edges GX, Gy of the mother glass G, respectively, two

initial cracks

10, 12 can be formed using the scribing head 5. Therefore, the

initial cracks

10 and 12 do not need to be separately formed by using another tool, and the operation of forming the scribe line 11 is simplified.

Fig. 12 shows a first modification of the scribing step 2. In the first modification, four unit

concave lines

6C, 6D, 6E, and 6F are formed on the surface Gh of the mother glass G, and the initial crack is extended along the unit concave lines 6C to 6F, thereby forming the scribe line 11 in which the four

unit scribe lines

11C, 11D, 11E, and 11F are continuously connected. In detail, the first unit scribing line 11C is formed by moving the scribing head 5 in the direction indicated by the arrow C over the bent line segment 4C1, the straight line segment 4C2, and the first unit extension line 4C3 of the line to cut 4. The second unit scribe line 11D is formed by the scribe head 5 moving in the direction indicated by the arrow D over the bent line part 4D1, the straight line part 4D2, and the second unit extension line 4D3 of the line 4 to cut. The third unit scribing line 11E is formed by the scribing head 5 moving in the direction indicated by the arrow E over the bent line part 4E1, the straight line part 4E2, and the third unit extension line 4E3 of the line 4 to cut. The fourth unit scribing line 11F is formed by the scribing head 5 moving in the direction indicated by the arrow F over the bent line part 4F1, the straight line part 4F2, and the fourth unit extension line 4F3 of the line to cut 4. The shape of the closed curve 4R is the same as the closed curve 4R shown in fig. 7 described above. The process of forming the four unit concave lines 6C to 6F, the process of forming the four initial cracks, and the process of extending the four initial cracks along the four unit concave lines 6C to 6F, respectively, are performed based on the matters described in detail.

Fig. 13 shows a second modification of the scribing step 2. In the second modification, two unit concave lines 6H and 6I are formed on the surface Gh of the mother glass G in a circular shape with the closed curve 4R being formed, and the initial crack is stretched along the unit concave lines 6H and 6I, respectively, thereby forming the scribe line 11 in which the two unit scribe lines 11H and 11I are continuously connected. More specifically, the first unit scribing line 11H is formed by the scribing head 5 moving in the direction indicated by the arrow H over the semicircular portion 4H1 of the line to cut 4 and the first unit extension line 4H2 linearly extending from one end thereof. The second unit scribe line 11I is formed by the scribe head 5 moving in the direction indicated by the arrow I above the semicircular portion 4I1 of the line to cut 4 and the second unit extension line 4I2 linearly extending from one end thereof. The process of forming the two unit concave lines 6H and 6I, the process of forming the two initial cracks, and the process of extending the four initial cracks along the two unit concave lines 6H and 6I are performed based on the matters described in detail.

Fig. 14 shows a third modification of the scribing step 2. In the third modification, four unit

concave lines

6J, 6K, 6L, and 6M are formed on the surface Gh of the mother glass G in a circular shape as in the above-described closed curve 4R, and the initial crack is extended along the unit concave lines 6J to 6M, thereby forming the scribe line 11 in which the four

unit scribe lines

11J, 11K, 11L, and 11M are continuously connected. Specifically, the first unit scribing line 11J is formed by the scribing head 5 moving in the direction indicated by the arrow J over the quarter-circle portion 4J1 of the line to cut 4 and the first unit extension line 4J2 linearly extending from one end thereof. The second unit scribing line 11K is formed by the scribing head 5 moving in the direction indicated by the arrow K over the quarter-circle portion 4K1 of the line 4 and the second unit extension line 4K2 linearly extending from one end thereof. The third unit scribe line 11L is formed by the scribe head 5 moving in the direction indicated by the arrow L over the quarter circle portion 4L1 of the line 4 and the third unit extension line 4L2 extending linearly from one end thereof. The fourth unit scribing line 11M is formed by the scribing head 5 moving in the direction indicated by the arrow M over the quarter circle portion 4M1 of the line to cut 4 and the fourth unit extension line 4M2 linearly extending from one end thereof. The process of forming the four unit concave lines 6J to 6M, the process of forming the four initial cracks, and the process of extending the initial cracks along the four unit concave lines 6J to 6M, respectively, are performed based on the details described above.

In the embodiments shown in fig. 11 to 14, each unit extension line reaches the end edge of the mother glass, but each unit extension line may not reach the end edge of the mother glass. The initial crack in this case can be formed, for example, by pressing a scoring wheel on the surface of the mother glass so as to intersect the unit extension line and moving the scoring wheel. In addition, the structure may not have each unit extension line. In this case, the initial crack can be formed by pressing a pin-like member or the like against one portion of each unit concave line, for example.

Next, the breaking step 3 performed after the scribing step 2 will be described. The breaking step 3 utilizes negative pressure suction. Note that, in the breaking step 3, the mother glass G on which the scribe line 11 of the form shown in fig. 11 is formed will be described. The supporting member 13 shown in fig. 15a and 15b is used for the execution of the breaking step 3. The supporting member 13 has a flat supporting surface 13a for supporting the mother glass G in a flat posture, and the supporting surface 13a includes a groove-shaped recess 14. The concave portion 14 is formed so that the concave portion 14 extends along the scribe line 11 when the mother glass G is supported by the support member 13. The support member 13 is preferably made of resin or the like so as to avoid scratches or the like when the mother glass G is placed thereon.

The recess 14 has a rectangular outline shape in a cross section orthogonal to the direction in which the groove extends. A plurality of suction holes (not shown) are formed in the inner wall surface 14a of the recess 14, and each suction hole is connected to a negative pressure generation source (not shown) such as a vacuum pump. As a result, the negative pressure generating source is operated in a state where the concave portion 14 is covered with the mother glass G, and the gas in the concave portion 14 is sucked through the suction hole, so that the negative pressure can be generated in the concave portion 14.

When the breaking step 3 is performed using the apparatus having the above-described structure, as shown in fig. 16a and 16b, the mother glass G is placed on the supporting member 13 such that the surface Gh (the surface on the side where the scribe line 11 is formed) of the mother glass G comes into contact with the supporting surface 13a of the supporting member 13. Then, the mother glass G is placed on the support member 13 such that the scribe line 11 formed in the mother glass G is positioned at the center of the opening width of the concave portion 14. In addition, the mother glass G on the support member 13 is covered with the cover member 15. The cover member 15 includes: a sheet 16 having flexibility and air-tightness; and a holding body 17 for holding the sheet body 16. The holding body 17 is not deformed even if negative pressure is generated, but the sheet body 16 has a characteristic of being easily bent due to the generation of negative pressure.

In this state, as shown in fig. 16a, the negative pressure generating source is operated to suck the gas in the hermetically sealed concave portion 14 as shown by an arrow W, thereby generating a negative pressure in the concave portion 14. Then, the peripheral region of the scribe line 11 existing on the concave portion 14 is bent by the negative pressure so as to be convex toward the surface Gh side, and the central crack included in the scribe line 11 is stretched in the thickness direction of the mother glass G by the stress generated thereby. As a result, as shown in fig. 16b, the mother glass G is broken starting from the scribe line 11, and the glass sheet G1 having the outer contour shape of the closed curve 4R is separated from the mother glass G. The glass sheet G1 becomes the product or raw material for the product, and the remaining glass portion G2 becomes the unnecessary portion. According to the breaking step 3 using this negative pressure suction, the glass sheet G1 can be cut with high quality.

The method for producing a glass plate of the present invention is not limited to the embodiment described above. For example, the shape of the closed curve of the line to cut may be a shape other than the above-described exemplified shapes, or the line to cut may be assumed to be constituted by the unit lines to cut other than the above-described exemplified number. In the breaking step, a method of pressing a tool or the like to an outer region of the closed curve of the mother glass to apply an external force may be used instead of the negative pressure suction.

Description of the reference numerals

1 preparation step

2 scribing Process

3 breaking step

Line to cut 4

Line to cut 4A Unit

4A3 unit extension wire

Line to cut 4B units

4B3 unit extension wire

4R closed curve

4R1 unit closed curve

4R2 unit closed curve

5 scribing head

6 concave line

6A unit concave line

6B unit concave line

10 initial cracking

11 scribing line

11A unit scribing line

11B unit scribing line

12 initial cracking

G mother glass

G1 glass plate

Surface of Gh glass plate

End edge of Gx glass plate

Gy edge of the glass plate.

Claims

1. A method for producing a glass sheet,

the method for manufacturing the glass plate comprises the following steps: a preparation step of preparing a mother glass and a scribing head for forming a concave line caused by plastic deformation on a surface of the mother glass by moving while pressing the surface of the mother glass; a scribing step of forming a scribing line along a line to cut including a closed curve on the surface of the mother glass; and a breaking step of breaking the mother glass along the scribe line to separate the glass plate having an outer contour shape corresponding to the closed curve from the mother glass,

in the scribing step, the closed curve is assumed to be formed of a plurality of unit closed curves which are continuously connected, and the line to cut is assumed to be formed of a plurality of lines to cut including the plurality of unit closed curves, and the scribing head is moved while being pressed along the plurality of lines to cut, so that unit concave lines caused by plastic deformation are formed for each of the plurality of lines to cut, and then, initial cracks corresponding to the unit concave lines are formed, and the initial cracks are extended along the unit concave lines, so that the scribing line formed by continuously connecting the plurality of unit scribing lines is formed.

2. The method for producing glass sheet according to claim 1,

in the scribing step, the plurality of lines to cut unit are two lines to cut unit.

3. The method for producing a glass sheet according to claim 1 or 2,

in the scribing step, the unit closed curve has a straight line portion and a curved line portion.

4. The method for producing a glass sheet according to any one of claims 1 to 3, wherein,

in the scribing step, each of the plurality of lines to cut unit is constituted by the unit closed curve and a unit extension line extending from one end of the unit closed curve to the outside of the closed curve.

5. The method for manufacturing glass plate according to claim 4,

in the scribing step, one of the plurality of unit closed curves and the other unit closed curve adjacent to the one unit closed curve each have a straight line portion and a curved line portion continuous to the straight line portion, and a unit extension line extending from one end of the one unit closed curve extends along the same straight line as the straight line portion of the one unit closed curve and extends along a tangent line of the curved line portion of the other unit closed curve.

6. The method for producing glass sheet according to claim 4 or 5,

in the scribing step, the unit extension line reaches an end edge of the mother glass.