JPS6012289B2 - How to bend a glass plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for folding glass sheets at relatively sharp angles.

Recently, in response to the diversification of automobile designs, glass plates bent relatively sharply into a V-shape or ] shape have begun to be used.

For example, a method for manufacturing this glass plate is to print conductive silver paste in stripes on the surface of the glass plate along the bending line where the glass plate is to be bent at a sharp angle, and to apply a voltage to the printed wire of the conductive silver paste. There is a method in which the curved line portion is heated to a temperature higher than the softening point of the glass plate by applying current and heated, and the curved line is sharply bent along the curved line, or a heater wire such as a nichrome wire is used instead of the conductive silver paste. A method is known in which a glass sheet is brought into contact with a curved line on the surface of a glass plate and heated with electricity, the glass plate at the curved line portion is heated to a temperature equal to or higher than its softening point, and the glass plate is sharply bent along the curved line. however,
In the case of the former method, the conductive silver paste printed lines remain on the product as opaque printed lines even after bending, which is undesirable in terms of appearance, and in the latter method, the heater filaments come into contact with the glass plate surface. As a result, traces of heater streaks remained on the curved portion of the glass plate, which was undesirable in terms of appearance. In addition, each of the above-mentioned methods heats the curved portion of the glass plate by conduction of heat from the heater filaments, and therefore has the disadvantage that it takes time to heat the curved portion. In addition, due to the heating caused by thermal conduction of the heater wires, the vicinity of the bending line of the glass plate was heated to a higher degree, making it difficult to bend the glass plate sharply. The present invention was invented as a result of research with the aim of improving the above-mentioned drawbacks, and is a conductive wire trigger for triggering a current on the bending line of a glass plate when the glass plate is to be bent sharply. A current is passed through the conductive wire trigger to generate heat L. This heat and the heat generated by burning the conductive wire trigger heat the curved portion of the glass plate. The bent line part of the glass plate is made conductive so that a current flows inside the glass plate, and the bent line part of the glass plate is thereby heated by Joule heating to a temperature above the softening point of the glass plate, and the curved line part is heated along the bent line. It is shaped so that it is bent sharply.

According to the present invention, since a current is applied directly to the bending line portion of the glass plate and the glass plate is heated by resistance heating, the heating speed is significantly faster than the case where heat is generated by the heater wires as described above, and the bending process can be easily performed. It can save you a lot of time.

For example, the bending process can be performed in units of several seconds to several tens of seconds, making mass production easy. In addition, since the bending line part is directly resistance heated, the heating area can be made narrower than in the case where heat is generated by the heater strips as described above, and the heating area is sharper, for example, the curvature of the outer surface of the glass plate at the bending part can be made narrower. 3
It can be bent into a sharp curvature less than a dish. The present invention will be explained in more detail below.

FIG. 1 shows a front view of an automobile window glass plate manufactured according to the present invention, and this glass plate 1'
It is sharply bent along bend line 2.

In manufacturing this glass plate according to the present invention, first, an electrically conductive linear trigger 3 is formed at a desired bending line 2 of the glass plate 1 to be bent.

This conductive wire trigger 3 has the function of heating the glass plate, which is non-conductive at room temperature, to a high temperature where it becomes conductive. If a high frequency current is used as the current, it is formed into a discontinuous line to the extent that this current flows. The conductive wire trigger 3 is preferably provided along a curved line in the surface direction from one end of the glass plate to the other end, as shown in FIG. The conductive filament trigger becomes a torrent at the beginning of energization and heats the curved line of the glass plate to a temperature at which it becomes conductive, and then the filament itself burns and heats the curved line of the glass plate to a high temperature. If the glass plate becomes conductive, current will flow through the curved line of the glass plate, and the glass plate will be made of a material that burns out at a temperature of 600 qo or higher so that the curved line becomes a bridge. Particularly preferred. If the conductive wire trigger is made from a material that burns out in this way, it is possible to effectively conduct electrical heating of the bent twill portion of the glass plate. Of course, materials that do not disappear even at high temperatures can be used.For example, conductive wire triggers include conductive carbon paste, carbon paint, silver base, etc.
It is possible to use strips printed or coated with various conductive pastes, paints, or suspensions, carbon or conductive metal ribbons, lines, or rods.

Among them, carbon paste or carbon paint, which burns out due to combustion at temperatures of 60,000 to 800 degrees Fahrenheit, or conductive wire triggers with ribbon-shaped carbon attached, can quickly heat the curved portion of the glass plate. It is ideal because it not only allows for the formation of filaments, but also leaves no filaments even after being folded. When using a flame burner electrode, it is best to use a material with high resistance, such as carbon paste or low melting point metal paste, which has a resistance similar to that of the flame burner electrode. It is better to apply The length of the conductive wire trigger varies depending on the power supplied, the angle at which the glass plate is bent, the curvature, etc., but the most practical length is between 1 rib and 5 ribs.

The conductive wire trigger may be provided on the inside surface of the bending line of the glass plate, or may be provided on the outside of the bending line, or may be provided on both sides thereof. The glass plate with conductive wire triggers formed along the bending line to be bent is placed on a gravity bending die 4 having a profile that allows it to be bent into a desired shape, as shown in FIG. 3, for example. A power source is electrically connected to the conductive filament trigger so that current flows through the filament trigger.

As the connection means for connecting the conductive wire trigger and the lead wire of the power source, a connection terminal such as a metal clip or a force-bond clip, a flame burner electrode, or the like is used.

If flame burner electrodes are used, like mechanical contact terminals, it is possible to prevent deformation, roughness, or devitrification of the glass plate at the connection part, suppress a decrease in strength, and prevent the glass from bending when the glass plate is bent. It is also easy to connect to the curved portion of the glass plate as it moves.

Further, in the case of a flame burner electrode, the strength can be improved by fire polishing the glass slope part of the current feeding part. The flame burner electrode is a glass plate bending method in which silver paste is printed on the bending line of the glass plate as described above, and the printed wire is heated with electricity to soften the bending line part of the glass plate. It is unsuitable for low resistance silver-based printed wires.
This is because the resistance of the flame burner electrode is significantly higher than that of silver paste printed wires, and it is difficult to control the resistance, which makes it possible to uniformly heat the curved line of the glass plate up to the softening temperature of the glass plate. This is because it is difficult to make an electric wire that can keep the current flowing through the silver paste printed wire constant, for example, about 10 μm. On the other hand, in the case of a high-resistance conductive wire trigger made of carbon paste or the like, the flame burner electrode and the wire have approximately the same resistance value, making it easier to design the power supply circuit. , practical.

In the present invention, as the current applied to the bending line of the glass plate after the conductive wire trigger and the bending line part of the glass plate become conductive, an alternating current or a direct current with a frequency ranging from a commercial frequency to a high frequency is used. be done.

In particular, high-frequency current is preferable because high-voltage current can be easily obtained, it is effective for energization heating of a glass plate starting from a high resistance, and energization can be carried out by breaking a conductive wire trigger. Furthermore, even if a person receives an electric shock during work, high-frequency current is safer because it is conducted through the surface of the body rather than through the inside of the body like low-frequency current. Further, since the glass is electrically heated using high frequency waves, it is possible to use the flame burner electrode as described above, and it is possible to prevent the strength of the glass plate at the electrode connection portion from decreasing. Among them, 1 female H
High frequency currents in the range z to QM are most practical. 1
If it is lower than 0 KHz, it is difficult to obtain high voltage current, and when the conductive wire trigger breaks due to the direct influence of the conductance of the glass, it is insulated and it is difficult for current to flow along the curved line, and the glass plate It is disadvantageous because it takes time to heat up the curved part of the coil, and if the temperature is higher than about 8 M, the loss of the high frequency oscillator becomes large, interference waves are generated, or standing waves are generated. , or bending type,
In addition, it is undesirable because the bending tool is likely to be energized.

For example, when bending an automobile glass plate or a commonly used glass plate, the length of the bending line is usually 1.
It is important to select a frequency that does not cause standing waves between the curved lines that serve as the torrent of high-frequency current.

If a high-frequency current is passed through the bending line of the glass plate and a standing wave is generated in the electric machine, the bending line will not generate heat uniformly. For commonly used glass plates, it is preferable that the temperature be equal to or less than z on the same day because the above-mentioned drawbacks will not occur. Further, the voltage applied to the curved line portion of the glass plate to be bent and/or the conductive wire trigger is suitably in the range of 10,000 to 10,000 y.

When a current is applied to the conductive wire trigger of the glass plate and the glass plate is heated along the bent line part of the glass plate, a temperature difference occurs between the heating area of the bent line part of the glass plate and the other parts. To prevent heat cracking, the entire glass plate is
It is preferable to heat to 50 qo or more and below the softening point of the glass, for example, 600 qo or less. Note that heating the glass plate higher than 600°C will cause undesirable deformation such as doubling of the glass plate, and lower than 250°C will cause a temperature difference between the heated area of the curved line and other parts, leading to the risk of thermal cracking. Yes, it's not good. In addition, when bending a glass plate into a complicated shape, it can also be heated to a temperature of 600 qo or more. The glass plate with the conductive wire trigger formed along the bending line of the glass plate is placed in a heating furnace and heated to 250 qo to 60 qo.
When the electric current as described above is applied to the conductive filament trigger, the conductive filament trigger is electrically heated and the curved portion of the glass plate is heated to the extent that it becomes conductive. A current flows through the curved portion of the glass plate along the conductive wire trigger, heating the curved portion to a temperature above its softening point.

When a current begins to flow through the curved portion of the glass plate and further heats it up, the conductive filament trigger burns out. When the bending line portion of the glass plate reaches a softening point or higher due to this heat, it is bent sharply along the bending line by the action of a bending die for gravity bending. In addition, in the case of gravity bending, the bending line part of the glass plate may descend due to gravity during the bending process, so if necessary, lower the power supply electrode according to the descent of the bending line part of the glass plate. You can also do this. Also, during the bending process of the glass plate, the bending die can be designed so that the bending line part of the glass plate does not move, and the electrode for power supply can be arranged at this position. Although we have described an example in which the gravity bending method is applied as a method for sharply bending along the curve, it is of course possible to use not only the gravity bending method but also various bending methods such as the press bending method and the air form method.

After the bending process, the glass plate sharply bent by the method of the present invention can be strengthened or slowly cooled, if necessary. Examples of the present invention will be described below.

Example 1 Carbon paste was printed on the middle three ribs of a rectangular glass plate of 50 foxes x 100 skins x 5 sides along the bending line (50 arcs in length) of the center line to be bent, and a conductive wire trigger was formed. was formed.

This glass plate was placed on a bending die for gravity bending, and clip electrodes connected to a high-frequency power source were connected to both ends of the conductive wire trigger. After this glass plate was placed in a heating furnace and heated to 52 to 0, a high frequency current with a frequency of 3 Hz and an applied voltage of 2000 V was passed through the conductive wire trigger. The glass plate could be bent sharply along the above-mentioned bending line when a high-frequency current was passed through it for one length of inkstone sand. In the embodiments and drawings, the case where the glass plate is bent into a V-shape has been described, but the present invention is not limited to this shape, but can be applied to various types of bending, for example, the bending of glass plates in various shapes such as ] shape, L shape, etc. I can do it.

[Brief explanation of the drawing]

FIG. 1 shows a sharply bent glass plate, FIG. 2 shows a glass plate with a conductive wire trigger formed thereon, and FIG. 3 shows an example of an apparatus for carrying out the method of the invention. DESCRIPTION OF SYMBOLS 1...Glass plate, 2...Bending line, 3...Electroconductive linear trigger, 4...Bending mold, respectively. Multi-speckled 2 broadsides increased by 3

Claims (1)

[Scope of Claims] 1. A conductive filament trigger is formed on the bending line of the glass plate where the glass plate is to be bent sharply, and a current is applied to the conductive filament trigger to form the conductive filament trigger on the bending line part of the glass plate. The trigger generates heat to make it conductive, and the current is applied to the bent line, thereby heating the bent line of the glass plate to a temperature equal to or higher than the softening point of the glass plate, and causing the glass plate to move along the bent line. A method of sharply bending a glass plate. 2. Claim 1, characterized in that an alternating current of 5 MHz from the commercial frequency is applied to the conductive wire trigger.
How to bend a glass plate as described in section. 3. The method of folding a glass plate according to claim 2, characterized in that a high frequency current of 10 KHz to 5 MHz is applied to the conductive filament trigger. 4. The method of folding a glass plate according to claim 1, characterized in that a direct current is applied to a conductive wire trigger. 5. The method for bending a glass plate according to claim 1, characterized in that the conductive wire trigger is made of a material that burns out after the conductive wire trigger generates heat by applying an electric current. 6. The method of folding a glass plate according to claim 3, characterized in that a conductive wire trigger formed by printing carbon paste is used.