JPH09118535A - Method for cutting brittle material plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for cutting a brittle material plate which is capable of cutting this brittle material in compliance with the cutting lines in spite of recessed parts having a small radius of curvature and is easily cutting the material with an inexpensive device without using a costly device, such as laser. SOLUTION: A film of a conductive liquid is formed on the surface of the brittle material plate 1 along the cutting lines 4 by a wheel cutter 3 in the method for cutting the brittle material plate 1 by applying the cutting lines 4 on the brittle material plate by the wheel cutter 3, then breaking the plate. Current is then passed to this conductive liquid film to generate heat in the film, by which the brittle material plate 1 is broken.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cutting a brittle material, and more particularly to a method for cutting a glass plate having a closed curve shape such as a glass plate for an automobile.

[0002]

2. Description of the Related Art In order to cut a glass plate into a closed curve shape, usually a jig such as a wheel cutter is used to give a cut line having a closed curve to the glass plate, and the tensile stress is given to the cut line by bending or heating. The method of making it break is taken. Among them, the bending stress is generated by mechanically bending the glass by hand or a machine, and the thermal stress is generated by heating the glass surface with a frame (flame) or a laser.

As a cutting method other than this wheel cutter, a method of melting the material at a high temperature by using a laser or a water jet processing method of jetting a liquid mixed with an abrasive at a high pressure to the material is known. There is.

Further, recently, a method of performing high quality cleaving while inducing a crack into an arbitrary curved shape using a laser has been developed.

Among these, the method of giving a cutting line using the above wheel cutter and giving a tensile stress to the cutting line to cut the line is widely used because it is simple. In particular, a method of breaking a glass by applying a thermal stress using a frame is easily adopted because it is easy to automate.

[0006]

If the closed curve of the cut line has a corner portion that is convex outward, even if the radius of curvature of the corner portion is relatively small, the breakage by the frame is
By optimizing the heating point by heating the outside of the corner (the outside of the closed curve) using a plurality of burners, it is possible to perform cutting according to the cut line without chipping or the like.

However, in the case of having a concave corner toward the outside of the closed curve, it is not possible to bring the heating point inside the closed curve because of the quality problem of the glass to be the product, and therefore the concave shape It cannot apply the stress of tearing the tip. If the radius of curvature of the concave shape is large, it can be broken by extension from around the crack, but if the radius of curvature is small, for example, if the radius of curvature is 5 mm or less with a glass plate with a thickness of 5 mm, the extended crack may crack. Will cause defects.

The laser fusing method and the water jet processing method, which were created in order to solve these problems, have a quality problem in that the melting surface is essentially not flat in the former case, and the processing speed is slow in the latter case. There is a problem in terms of efficiency, and both of them have a problem that the device itself is expensive. Both methods are not suitable for a method for simply and accurately cutting a closed curve shape having a small concave radius of curvature of the material. It can't be.

Further, the laser cleaving method has an advantage that a brittle material is not broken and a concave portion having a small radius of curvature can be accurately cut, but a carbon dioxide gas laser of several tens W class is required. Is relatively expensive.

According to the present invention, a brittle material plate can be cut even in a concave portion having a small radius of curvature according to a cutting line and can be easily cut by an inexpensive device without using an expensive device such as a laser. The purpose is to provide a cutting method.

[0011]

In order to achieve the above object, the present invention provides a method for cutting a brittle material plate that is cut by a wheel cutter and then ruptures the brittle material plate along the cutting line by the cutter wheel. A method of cutting a brittle material plate, characterized in that a film of a conductive liquid is formed on a surface, and an electric current is passed through the conductive liquid film to generate heat to thermally break the brittle material plate. It is preferable that cutter wheel oil having conductivity is used as the conductive liquid, and the oil is supplied to the rotary shaft pin of the wheel cutter.

According to the present invention, it is possible to perform the breaking at the same time as the formation of the cut line, easily and accurately cut the concave portion having a small radius of curvature, which has been a problem in the past, and the step and the step of inserting the cut line. The number of steps to be performed is reduced to one step, and productivity is improved. Further, as an applied voltage for passing a current through the conductive liquid film to generate heat, 300 V or less is sufficient, and there is an advantage that an expensive device is not required.

In the present invention, when the cutting wheel is applied to the brittle material plate with the cutter wheel, the electric current can be passed from the cutter wheel by making the cutter wheel oil conductive, and the heat generated by It is possible to cut the substrate by advancing the scoring lines in the vertical direction.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing a cutter wheel and a ground electrode used in the breaking method according to the present invention,
FIG. 2 is a diagram showing a conventional method of breaking by thermal stress due to a frame, for example.

In FIG. 1, a plate of brittle material, eg, 5
Using a wheel cutter 3 having a superhard metal wheel 2 having a diameter of 5 mm, a glass plate 1 having a thickness of mm is provided with a cut line 4 having an arbitrary closed curve shape. The foil 2 is rotatably held by a metal rotary shaft pin 6 at the lower end of the metal cutter shaft 5. At the upper end of the cutter shaft 5, there is provided a bellows cylinder 7 for applying a load to the wheel 2. Cutter wheel oil tank 8
From the above, the cutter wheel oil is supplied to the gap between the rotary shaft pin 6 and the foil 2 through the conduit 9.

A conductive liquid is used as the cutter wheel oil, but water containing alkanolamine added at a concentration of 10% by weight is used. At the tip of an electrically insulating rod 10 provided so as to extend from the cutter shaft 5 to the rear side in the traveling direction of the wheel cutter, a thin copper-made ground electrode 11 that comes into contact with the surface of the glass plate is installed, and the voltage generator 12 causes the cutter to move. Conductors 13 and 14 are respectively attached to the shaft 5 and the earth electrode 11.
Are tied. The distance between the tip of the ground electrode 11 and the lower end of the foil 2 was about 10 mm. Since the cutter shaft 5, the rotary shaft pin 6 and the wheel 2 are electrically connected, a DC voltage of 200 V is applied between the wheel 2 and the ground electrode 11.

While the wheel cutter 3 is run along the closed curve shape on the glass plate 1 to give the cutting line 4, the cutter wheel oil, which is a conductive liquid, continuously flows out from the lower end of the foil 2 to cut it. A strip of conductive liquid film 15 adheres to the surface of the glass plate along the lines. Wheel cutter 3
When the conductive liquid film 15 comes into contact with the ground electrode 11 as a result of progressing, a voltage is applied between the wheel 2 and the ground electrode 11 to cause a current to flow in the conductive liquid film 15 and generate Joule heat in the liquid itself. It is generated, the heat is transmitted to the glass,
Then, the glass was broken by applying a local thermal stress to the glass.

At this time, rib marks like cracks enter from the surface of the glass plate in the vertical direction (thickness direction) by the wheel 2. The depth of the rib mark-shaped crack depends on the load applied to the wheel 2, and is about 700 μm when 10 kg is applied by the belofram cylinder 7. The greater the depth of the rib mark-shaped crack, the easier the fracture.

The glass is heated by the Joule heat generation of the conductive liquid film 15. Due to the local thermal stress generated in the glass, a tensile force acts in the circumferential direction at a glass plate surface position having a radius (which differs depending on the size of the heating region but is, for example, about 40 mm) centered on the heating point. That is, a component force in the direction of tearing the kerf is generated, and immediately after the site where heat is generated, a rib mark-shaped crack generated in the kerf propagates in the vertical direction (thickness direction) and its depth (initially 700 μm) is 5000 μm (glass It is observed that the glass easily breaks along the cut line of the closed curve having concave corners toward the outside with a radius of curvature of about 5 mm without causing defects such as chipping. Was done.

The width of the liquid on the glass surface is preferably from 5 mm to 20 mm in order to effectively generate Joule heat and give a local thermal stress to the glass. Regarding the DC or AC voltage for flowing the current, the higher the voltage, the more quickly the heat is generated, which is preferable. However, if the voltage is too high, it is a safety problem, so it is appropriate to use it in the range of 50 to 300V. Is.

Conventionally, the frame 16 shown in FIG. 2 is used to break along the cut line 4 having a closed curved shape put in the glass plate 1. However, the problem may occur in the strength of the wheel or in the horizontal direction. However, there is a limit to the load that can be applied due to the increase of cracks that cause quality problems. Therefore, it is necessary to propagate the generated rib mark-shaped cracks to the lower surface of the glass, but in the conventional method of applying thermal stress using a frame, cutting of a closed curve with a corner having a small radius of curvature toward the outside is cut. It is not possible to generate enough force in the direction to tear the muscle.

Further, in the above embodiment, the electric current was passed between the wheel and the ground electrode. However, another electrode that comes into contact with the glass is provided immediately after the wheel, and Joule heat is generated between this electrode and the ground electrode. May be. As the conductive liquid, water in which various inorganic metal salts are dissolved can be used in addition to the water in which the alkanolamine is added.

[0023]

EFFECTS OF THE INVENTION By changing the cutter wheel oil to a conductive liquid, it becomes possible to generate an electric current by causing an electric current to flow, which makes it possible to extend a crack generated by a scoring line in a vertical direction and break it. Become. Moreover, since it is possible to locally generate heat, it is possible to cut even concave portions having a small radius of curvature according to the cutting lines, and simple cutting with an inexpensive device without using an expensive device such as a laser. Will be possible.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a cutter wheel and a ground electrode used in a breaking method according to the present invention.

FIG. 2 is a perspective view showing a thermal stress breaking method using a conventional frame.

[Explanation of symbols]

 1: Glass plate 2: Wheel 3: Wheel cutter 4: Cutting line 7: Bellofrum cylinder 10: Insulating support rod 11: Earth electrode 12: Voltage generator 15: Conductive liquid film 16: Burner for breaking

Claims (2)

[Claims] 1. A method of cutting a brittle material plate, which is ruptured after being provided with a cutting line by a wheel cutter, wherein a film of a conductive liquid is formed on the surface of the brittle material plate along the cutting line by the cutter wheel, and the conductive liquid is formed. A method for cutting a brittle material plate, which comprises causing an electric current to flow through the film to generate heat to thermally break the brittle material plate. 2. The method for cutting a brittle material plate according to claim 1, wherein a cutter wheel oil having conductivity is used as the conductive liquid, and the oil is supplied to a rotary shaft pin of the wheel cutter.