JP3733617B2 - Fracture method of brittle material plate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for breaking a brittle material, and more particularly to a method for breaking a glass plate along a curved cut line.
[0002]
[Prior art]
To break the glass plate in a curved shape, giving the cut muscle curve glass with冶tool such as carbide wheel, the method occupied lead to fracture by giving stress to the cut muscle is taken. This stress was either generated by bending the glass by hand or machine, or generated thermally by heating the glass with a flame (combustion flame) or laser. In particular, the latter is a method suitable for automatically performing glass breakage, and has been widely used for curving glass.
[0003]
[Problems to be solved by the invention]
This method of breaking glass by heating it with a frame or laser applies the fact that tensile stress acts in the circumferential direction in a region away from the heating point, and the tensile stress is perpendicular to the cut line. By applying the component force of, the glass is torn according to the score and breaks.
[0004]
As shown in FIGS. 6 and 7, when the brittle material plate is broken along the curved cut line 23 having the corner portion 20 by using this breaking method, the two sides 24 and 25 sandwiching the corner portion 20 When the heating point D is placed on the extension line 26 of one of the sides 24, the cut line on the side 24 is accurately broken, but the other cut line 25 is not broken. In order to prevent this, it is necessary to apply stress evenly to each side, and the heating point C is usually placed on or near the bisector of the angle between the two sides 24 and 25 connected to the corner 20. The method is adopted.
[0005]
In this method, the curvature of the cut corner portion is expressed as a curvature radius of 30 mm with a thin plate having a thickness of 3 mm or less (hereinafter, a numerical value in which the curvature radius is expressed in mm after R, such as R30, for example). When the radius of curvature is larger than that, or when the thickness is about 5 mm and the curvature of the corner is R100 or larger than that, there will be no occurrence of cracks, hooks, etc. Breaking is performed according to the scissors, but when the thickness is about 3 mm or less and the corner curvature is about R10, or the thickness is about 5 mm and the corner curvature is greater than or equal to R30 or a smaller radius of curvature. Then, the problem that a crack etc. generate | occur | produced or a fracture | rupture was not performed according to the cut line had generate | occur | produced.
[0006]
The present invention solves the above-described problems and allows a brittle material plate such as a glass plate having a cut corner having a small radius of curvature to be cut along the cut line without causing cracks or the like. The purpose is to break as usual.
[0007]
[Means for Solving the Problems]
The present invention relates to a method of breaking a brittle material plate having a cut line having a corner along the cut line, and at a corner end of the cut line, a bisector of an angle constituting the corner part. in line through a by corner tip vertical, and by heating the predetermined distance away brittle material plate portion from the Kakubu tip first, to generate initial crack, then the cut muscle other than the angle tip, Whether the crack is developed by heating the brittle material plate portion on the bisector of the corner constituting the corner and spaced apart from the corner tip by a predetermined distance to the outside of the corner, following the initial heating. Or a method of breaking a brittle material plate, characterized by generating an independent crack.
[0008]
The present invention will be described below with reference to the drawings by taking a glass plate as an example.
1 to 3 show a method in which a substantially triangular glass plate is broken along the cut line 1 from a rectangular glass plate 2 with a cut line 1 having a substantially triangular closed curve. When cutting a substantially triangular glass plate 3 along the cut line 1, the angle is perpendicular to the bisector 5 of the angle forming the corner 4 (the angle formed by the extension lines of the two sides sandwiching the corner). A first heating point A is provided on a glass plate portion 7 on a line 6 passing through the tip of the portion 4 and a predetermined distance away from the tip of the corner. Then, a second heating point B is provided on the glass plate portion 8 on the bisector 5 of the angle constituting the corner and a predetermined distance away from the corner tip to the outside of the corner 4. Then, the glass plate breaks by first heating the first heating point to generate an initial crack at the corner tip, and then heating the second heating point to the cutting line other than the tip. The crack propagates or an independent crack is generated.
[0009]
Here, heating for generating cracks in the cut lines will be described.
A premixed frame (eg, calorie 3000 cal / hr, frame diameter of about 20 mm) made by burning a gas flow in which air or oxygen is premixed in a gaseous fuel such as city gas, the frame tip contacts the glass surface. In the state, when one point on the surface of the glass plate is heated from the vertical direction, the temperature distribution on the glass plate surface, that is, the temperature (° C.) at the radial distance (mm) of the glass plate surface from the heating point is measured. As shown in FIG. 4, the distribution shape is almost a normal distribution with the heating point being point-symmetric. Numbers 1 to 5 in the figure represent respective temperature distributions for every 1 to 5 seconds elapsed from the start of heating. The spread of this distribution varies depending on the size and shape of the frame. When using a laser instead of a frame as a heating source, the heating area can be reduced by reducing the diameter of the laser beam at a position in contact with the glass surface to about 0.1 to 0.5 mm, for example. Sharp temperature distribution with high center temperature and little spread.
[0010]
When the thermal stress generated on the glass surface by this heating is decomposed into plane thermal stress components in the radial direction and the direction perpendicular to the radial direction (hereinafter referred to as the circumferential tangential direction) at a distance measured with the heating point as the center, All the stresses in the direction are compressive stresses, and the greatest compressive stress works near the heating point, and the compressive stress gradually decreases as the distance from the heating point increases, whereas the circumferential tangential stress is near the heating point. It is observed that the maximum compressive stress works, the compressive stress gradually decreases until a certain distance from the heating point, and thereafter becomes tensile stress, shows the maximum tensile stress value at a certain position, and then gradually decreases.
[0011]
FIG. 5 shows the distribution of the stress value (kg / mm ² ) in the circumferential tangent direction at the radial distance (mm) of the glass plate surface from the heating point. Numbers 1 to 5 in the figure correspond to FIG. 4 and represent respective stress distributions for each elapse of 1 to 5 seconds from the start of heating. From this figure, compressive stress is applied in the circumferential tangential direction up to a radius of 17 to 18 mm with the heating point as the center, and tensile stress is applied beyond that, showing a maximum tensile stress value at a radius of 40 to 60 mm, and thereafter gently Decrease. When the heating area is smaller, the amount of heat given to the glass surface unit area per second is larger, or the heating temperature is higher and the temperature distribution shown in FIG. 4 becomes sharper, the compressive stress in FIG. 5 changes to the tensile stress. 5 and the maximum position of the tensile stress are further closer to the heating point, for example, the radial distance indicating the maximum tensile stress value is shortened to, for example, 20 to 30 mm, and the circumferential tangential direction in the vicinity of the maximum tensile stress point in FIG. The stress distribution becomes sharp. Therefore, a large tensile stress acts in the vertical direction of the cut line portion by heating the glass surface position on the extension line of the cut line portion at least 30 mm or more, preferably 40 to 60 m from the cut line portion for 1 to 5 seconds. As a result, cracks occur in the thickness direction of the glass plate and reach the surface opposite to the cut line of the glass plate.
[0012]
In the present invention, as shown in FIGS. 1 to 3, the first heating point A, that is, perpendicular to the bisector of the angle forming the corner 4 of the scoring line, on the line 6 passing through the tip of the corner In addition, initial cracks are generated at the corner tips by first heating the glass plate portion 7 at a predetermined distance from the corner tips, for example, at least 30 mm or more, preferably 40-60 mm away. Heating is performed, for example, by burning a premixing frame 10 (heat quantity 1000 cal / hr) emitted from a side burner 9 disposed at the first heating point A of the glass plate for 1 to 5 seconds. As a result, tensile stress is applied in the direction perpendicular to the cut line at the corner tip, and an initial crack is generated from the cut line at the corner tip toward the plate thickness direction to reach the lower surface of the glass plate.
[0013]
Next, on the second heating point B of the glass plate, that is, the bisector 5 of the corner constituting the corner 4 and a predetermined distance from the tip of the corner to the outside of the corner, for example, at least 30 mm or more, preferably 40 The glass plate part 8 separated by -60 mm is heated. Heating is performed, for example, by burning a premixing frame 12 (heat quantity 3000 cal / hr) emitted from the main burner 11 arranged at the second heating point of the glass plate for 1 to 5 seconds. By the heating at the second heating point, the initial crack generated by the heating at the first heating point progresses toward the cut lines on the two sides sandwiching the corner. When the maximum tensile stress generation position due to heating at the second heating point is slightly inward from the tip of the corner, an independent crack may be generated at the cut line on the two sides apart from the initial crack. The crack comes into contact with the initial crack, and in any case, there is no occurrence of cracks, sag, etc., and the fracture according to the cut line is performed. If 1 second has elapsed from the start of heating at the first heating point, the initial crack has already occurred, so the heating at the second heating point should be at least 1 second from the start of heating at the first heating point. You may start.
[0014]
The generated heat amount of the main burner 11 provided at the second heating point needs to be 1000 to 10000 cal / hr. Since the side burner 9 provided at the first heating point only needs to locally heat only the corners, the amount of generated heat may be smaller than that of the main burner, and is preferably in the range of 300 to 10,000 cal / hr. The side burner may be provided on one side of the bisector as described above, but may be provided on both sides of the bisector. The main burner and the side burner may be provided separately, but after heating at the position of the above side burner using only one burner, the position of the main burner is immediately maintained while continuing the combustion or interrupting the combustion. The burner or the glass plate may be moved and heated.
[0015]
If the side burner is not used and the flame is heated only by the main burner, the following inconvenience occurs. The crack generation phenomenon will be described with reference to FIGS. When the heating point of the frame 22 by the main burner 21 is placed at a point C on the bisector of the corner 20 of the curved cut line, the cut line portions 24 and 25 existing in a region 3 cm or more away from the heating point are formed. Cracks occur. However, with respect to the tip of the corner 20, the cut line portion extends in the circumferential tangential direction as viewed from the heating point, and since a compressive force is always acting in the direction perpendicular to the cut line, no cracks are generated. The tip remains unbroken, and when an external force is mechanically applied later, it breaks away from the cut line, resulting in defects such as cracks and hooks. This phenomenon becomes more prominent as the radius of curvature of the corner becomes smaller and the plate thickness increases. This phenomenon is the same even when the heating point is separated from the bisector. In an extreme case, when the heating point D is placed on the extended line 26 of the side 24, only one side 24 cracks. However, no cracks occur on the other side 25, and no cracks occur on the cut lines at the corner tips.
[0016]
Since the present invention temporarily generates a temperature difference in the brittle material plate to generate thermal stress, the heating means used in the present invention is a rapid heating of the brittle material such as a gas burner or a laser heating device. Those that can be heated locally are suitable, and those that heat gradually and over a wide range, such as hot air heating, are inappropriate.
[0017]
The present invention can be applied to a glass plate having a thickness of 2 to 20 mm, a ceramic plate or other plate of a brittle material. For a plate having a thickness of 3 mm or less, the corner of the cut line has a curvature radius of 1 to 20 mm. When the brittle material plate having a thickness of 5 mm or more is applied to the brittle material plate having a curvature radius of 2 to 80 mm at the corner of the cut line, a great effect can be obtained.
[0018]
In addition, the present invention has a remarkable effect when the angle between two sides sandwiching the corner of the brittle material plate to be broken is 120 degrees or less. When this angle exceeds 120 degrees, the conventional method can be ruptured according to the cut line without the occurrence of chipping.
[0019]
The above describes the case where the heating means is used as a means for generating an initial crack at the corner tip of the cut line and a means for causing the crack to propagate to a cut line other than the tip part or as a means for generating an independent crack. However, a tensile stress may be generated inside the brittle material plate by using a cooling means such as dry ice instead of heating. However, it goes without saying that the cooling position is different from that in the case of heating.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0021]
As shown in FIGS. 1 to 3, the float glass plate 2 having a soda-lime silicate glass composition having a thickness of 5 mm and 3 mm, each having a thickness of 5 mm and 3 mm, has two types of shapes ( After inserting a cut line 1 having a closed curve having corner radii of curvature of 30 mm and 5 mm, the glass plate is broken along this curve to obtain a substantially triangular glass plate 3. In both types of closed curves, the corner 15 between the side 13 and the side 14 and the corner 17 between the side 14 and the side 16 have a radius of curvature larger than 100 mm. The corner 4 between the side 16 and the side 13 has a radius of curvature of 30 mm and 5 mm. The angles between the side 16 and the side 13 are both 50 degrees, and the breakage of the corner 4 becomes a problem. The fracture failure was compared by applying the fracture method according to the present invention using a side burner and a main burner and the fracture method using only a conventional main burner. The failure to break was defined as a case in which cracks or hooks were generated at the corners, or the breakage did not follow the cut lines.
[0022]
The incisor was given with a load of 8 kg using a wheel cutter having a super-hard wheel having a diameter of 5 mm. Also, with the side frame 10 (heat quantity 1000 cal / hr, frame diameter 8 mm), the heating point A located at a distance of 50 mm from the apex of the corner started to be heated, and 2 seconds later the main frame 12 (heat quantity 3000 cal / hr, frame diameter 20 mm), heating of the heating point B located at a distance of 50 mm from the corner apex was started and heated for about 3 seconds. For comparison, a test performed in the same manner as described above without igniting the side burner was used as a comparative example.
In both the examples and comparative examples, 200 pieces of rupture tests were performed for each of the four types of samples, and the non-defective product ratio, which is the ratio of the 200 sheets that do not cause breakage failure, is shown in Table 1. From Table 1, it can be seen that the greater the thickness and the smaller the radius of curvature, the greater the effect of the present invention.
[0023]
[Table 1]
==============================
Thickness Curvature Example Comparative Example ------------------------------
3mm R30 100% 99.5%
3mm R5 99.5% 82%
5mm R30 100% 92%
5mm R5 99.5% 63%
==============================
[0024]
【The invention's effect】
By generating an initial crack using a side frame at the tip of the curved corner, it becomes easy to break the tip, which was difficult to crack by the conventional method, and it is possible to break along the scoring line without cracks etc. It became possible.
[Brief description of the drawings]
FIG. 1 is a plan view showing a breaking method using a side burner and a main burner according to an embodiment of the present invention.
FIG. 2 is a partially enlarged view of FIG.
FIG. 3 is a perspective view of FIG. 2;
FIG. 4 is a graph showing the temperature distribution on the glass surface when the glass surface is heated with a frame.
FIG. 5 is a graph showing a stress distribution in the circumferential direction on the glass surface generated by the temperature distribution of FIG. 4;
FIG. 6 is a plan view showing a breaking method using only a main burner in a conventional method.
7 is a perspective view of FIG. 6. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cut line 2 Brittle material board 4 Corner part A of cut line 1st heating point B 2nd heating point

Claims (1)

In a method of breaking a brittle material plate containing a cut line having a corner along the cut line,
The corner tip of該切Ri muscle, a predetermined distance away brittle material plate portion from the line a and Kakubu tip through a by corner tip perpendicular to the bisector of the angle that constitutes the front Symbol corners first By heating, initial cracks are generated,
Then the cut muscle other than the angle tip, followed heated brittle material plate portion a predetermined distance away on the outside of the corner portion from a and Kakubu tip bisector of the angle forming the corner in the first heating A method for breaking a brittle material plate, wherein the initial crack is propagated or an independent crack is generated.

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