JPS6012978B2 - How to sharply 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 that are relatively sharply bent into a V-shape or ) shape have begun to be used.

The manufacturing method for this glass plate is, for example, to print conductive silver paste in stripes on the glass plate surface along the curved 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 bent line portion is heated to a temperature higher than the softening point temperature of the glass plate by applying an electric current and heated, and the bent line is sharply bent along the bent line, or a heater wire such as a nichrome wire is used instead of the conductive silver paste. A method is known in which the glass plate is brought into contact with a curved line on the surface of the glass plate and heated with electricity, the glass plate at the curved line is heated to a temperature higher than its softening point, and the glass plate is bent sharply along the curved line.

However, in the case of the former method, the printed lines of the conductive silver paste remain on the product as opaque printed lines even after bending, which is unfavorable in terms of appearance. Because the heater was in contact with the glass plate, traces of heater streaks were left on the curved line of the glass plate, which was unfavorable 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. Furthermore, 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 more sharply. Furthermore, since these methods use commercial power, there is a risk of electric shock during operation. As a method to improve the above-mentioned drawbacks, the present applicant previously formed a conductive wire trigger on the curved line of the glass plate for triggering a current to the curved line of the glass plate, and applied a high-frequency current to the conductive line trigger. is applied to cause the conductive wire trigger to generate heat, and this heat heats the curved portion of the glass plate, making the curved portion of the glass plate conductive, allowing a high-frequency current to flow inside the glass slope. An application was filed in which the bending line portion of the plate is heated by Joule heat to a temperature above the softening point of the glass plate, and the plate is sharply bent along the bending line.

According to this method, a current is passed directly to the curved portion of the glass plate to heat it by resistance heating, so the heating rate is much faster than when heat is generated by the heater wires as described above, and the bending process can be easily performed. The time can be significantly reduced.

For example, bending can be performed in units of several seconds to several tens of seconds, and mass production is easy. In addition, since the bending line portion 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 more sharp, for example, when the outer surface of the glass plate has a sharp curvature of 30R or less. It can be folded into However, in the above method, when power is supplied to the conductive wire trigger, if the clip connection terminal is connected to the end of the conductive wire trigger, the clip connection part becomes difficult to bend due to the resistance of the clip, and It was discovered that the glass portion at the end of the filament trigger reaches a temperature above its softening point, leaving clip marks at the clip connection, reducing the product value. We also attempted to extend the end of the conductive wire trigger along the periphery of the glass plate so that the clip could be connected to the conductive wire trigger on the side of the bending line, but this method also failed. Since the conductive wire trigger along the bending line and the extension part have almost the same resistance, the heat generation in the bending line part is small, and the bending line part of the glass plate is heated and becomes conductive. When the glass plate is bent, the electric path flowing through the glass plate no longer follows the bending line, making it difficult to bend the glass plate at a sharp angle. The present invention is an improvement on this point, and the end portion of the conductive wire trigger is formed along the bending line where the glass plate is to be bent sharply, and is made of a material having a lower electrical resistance value than the wire. IJ for attaching connection terminals such as IJ cups
A lead electrical circuit is connected to the wire and formed around the glass plate, and a high frequency current is applied through the lead electrical circuit.

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 is sharply bent along a bending line 2. In FIG.

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

The conductive wire trigger 3 serves to heat the glass plate, which is non-conductive at room temperature, to a high temperature where it becomes conductive. Or, if a high frequency current is used as the current, the twill is formed to be discontinuous enough to allow the current to flow. It is preferable that the conductive wire trigger 3 is provided along a curved line in the plane direction from one end of the glass plate toward the pond end, as shown in FIG. 2, for example. The conductive filament trigger becomes an open circuit at the beginning of energization, and is heated to a temperature at which the curved line of the glass plate becomes conductive.Furthermore, the filament itself burns and heats the curved line of the glass plate to a high temperature, causing the glass plate to become electrically conductive. When the plate becomes conductive, a high-frequency current flows through the bent line of the glass plate, and the bent line becomes a hazy path.The glass plate is made of a material that burns away at temperatures of 600°C or higher. Particularly preferred. If the conductive wire trigger is constructed from a material that burns out in this way, it is possible to effectively heat the bent portion of the glass plate with electricity, and this wire will not remain after the glass plate is bent. This may be preferable in terms of appearance. Of course, materials that do not disappear even at high temperatures can also be used. Examples of conductive wire triggers include conductive carbon paste, carbon paint, silver paste, and various other conductive pastes, paints, and suspensions printed or coated on the wire, and carbon or conductive metal triggers. A ribbon-like material, a linear material, a rod-like material, etc. can be used.

Among them, conductive wire triggers with carbon paste, carbon paint, or ribbon-shaped carbon attached, which burn out by combustion around the softening point of the glass plate, 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. The length of the conductive wire trigger varies depending on the power supply, the angle at which the glass plate is to be bent, the curvature, etc., but the most practical length is between 1 and 5 ribs.

The conductive wire trigger may be provided on the inside surface of the bending line of the glass plate, on the outside thereof, or on both sides thereof. In the present invention, leads 4 are connected to both ends of the conductive wire trigger 3 as described above for attaching connection terminals such as clips made of a material having a lower electrical resistance than the wire. Provided.

This lead section electric path 4 serves as a power supply section for energizing the conductive filament trigger 3 at the initial stage of energization, and for energizing the curved portion of the glass plate in the latter stage, and when the conductive filament trigger burns. It is preferable to use a material that does not burn out at a potential level that causes burnout. In addition, the electrical resistance value of the lead Toden line 4 is set so that the conductive wire trigger and the curved portion of the glass plate are heated effectively, and the glass plate is not deformed at the location where the connection terminal such as a clip is attached. The value is chosen to be lower than the conductive wire trigger and not to generate much heat when energized. For example, about 0.10 to 100 is appropriate. This lead part electric circuit 4 is arranged on one side or both sides of the curved line of the glass plate so that it is easy to connect the electrical connection terminal 5 such as a clip, and it is hidden in the window frame when the glass plate is iron-inserted. It is preferable to provide the conductive wire trigger electrically connected to the periphery of the glass plate, such as the periphery or end face of the glass plate on the side thereof, or a portion slightly inside the periphery of the glass plate.

For the lead circuit, conductive paste or conductive paint containing powder of conductive metal such as Ag, AI, Pd, Pt, low-melting glass frit, organic solvent, thickener, and other desired components is used. The glass plate has a liquid suspension printed on it, a metal tape made of nichrome, aluminum, silver, platinum, etc. on the glass plate, or the glass plate has a metallic coating in stripes. It is considered as the most suitable one.

Of course, it is not limited to this, and various types can be used within the scope of this purpose. The glass plate on which the conductive wire trigger and lead circuit are formed is placed on a gravity bending die 6 having a contour that allows it to be bent into a desired shape, and the power supply lead wire 7 is connected to the lead circuit. do. Lead Toden Route 4
The connection between the power supply lead wire 7 and the power supply lead wire 7 is performed using a connection terminal such as a metal clip or a carbon clip. 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 at a high frequency from the commercial frequency is used. Ru.

In particular, high-frequency current is preferred because a high-voltage current can be easily obtained, it is effective for energization heating of a glass plate starting from a high resistance, and it can be energized by breaking a conductive wire trigger. Also, even if a person receives an electric shock during work, high-frequency current does not conduct inside the human body like low-frequency current.
It is safer because it is surface conduction. Furthermore, since the glass is electrically heated using high frequency waves, it is possible to use a flame burner electrode as described above, and it is possible to prevent a decrease in the strength of the glass plate following the electrode. Among them, 10KHz
High-frequency currents in the range of ~ coronation z are the most practical. If the female ratio is lower than 1, it will be difficult to obtain a high voltage current, and if the conductive wire trigger breaks due to the direct influence of the conductance of the glass, it will be insulated and it will be difficult for current to flow along the curved line. It is disadvantageous because it takes time to heat the curved part of the plate, and if the frequency is higher than 5MHz, the loss of the high frequency oscillator increases, the generation of damage prevention radio waves, or the generation of standing waves. Alternatively, it is undesirable because it tends to cause energization of bending dies and other bending process odor control devices.

For example, when bending a glass plate for an automobile or a commonly used glass plate, the length of the bending line is usually one or two desks or less, so standing waves may occur between the bending lines that form the electrical path for high-frequency current. It is important to select a frequency that will not cause this. In addition, in the case of commonly used glass plates, it is preferable that the frequency is 8 MHz or less, since the above-mentioned drawbacks will not occur. In addition, the voltage applied to the bending line portion of the glass plate to be bent and/or the conductive wire trigger is 1000
A range of V to 10,000V is suitable. When a high-frequency current is passed through 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. hand,
In order to prevent thermal cracking, the entire glass plate is preferably heated to a temperature of 25,000°C or more and below the softening point of the glass, for example, 600°C or less. In addition, heating to a temperature higher than 600 qo may cause undesirable deformation such as doubling of the glass plate.
If it is lower than 50 qo, a temperature difference will occur between the heating area of the curved line portion and other portions, and there is a risk of thermal cracking, which is not preferable. In addition, when bending a glass plate into a complicated shape, it can be heated to a temperature of 60,000 or more. When the glass plate on which the conductive filament triggers are formed along the bending line of the glass plate is placed in a heating furnace and heated between 250 and 600°C, and then a current as described above is passed through the conductive filament triggers, The conductive filament trigger is heated with electricity, and the bent line part of the glass plate is heated to the extent that it becomes conductive.A current flows through the bent line part of the glass plate along the conductive filament trigger, causing the bending line to become conductive. When a high-frequency current begins to flow through the curved portion of the glass plate that is heated to a temperature above its softening point and is further heated, the conductive filament trigger burns and disappears.

When the bending line portion of the glass plate reaches a softening point or higher, 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.

Further, the bending die may be designed so that the bending line portion of the glass plate does not move during the bending process of the glass plate, and the power supply electrode may be placed at this position. In the above example, we have explained an example in which the gravity bending method is applied as a method of sharply bending the glass plate along the bending line, but the method is not limited to the gravity bending method, and various bending methods such as the press bending method and the air form method are also applicable. Of course, it can be used for.

The glass plate sharply bent by the method of the present invention can be strengthened or slowly cooled as required after the bending process. Examples of the present invention will be described below. Example 1 Carbon paste was printed on the middle three ribs of a glass plate measuring 70 arcs vertically, 160 arcs horizontally, and 5 legs thick to form a conductive wire trigger along the bending line of the center line to be bent. Then, by connecting both ends of the filament, an electric circuit having a length of 3 m and 1 m in length was formed around the perimeter of the glass plate.

This glass plate was placed on a bending die for gravity bending, and then lead wires connected to a high frequency power source were connected to the lead portion electric circuits at both ends with clips. After this glass plate was placed in a heating furnace and the whole was heated to 52,000 ℃, a high frequency current with a frequency of 3 Hz and an applied voltage of 3,000 V was passed through the upper lead portion.

When a high-frequency current was passed for one moment, the glass plate could be bent sharply along the bending line. 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, such as [] shape, L-shape, etc. I can do it.

[Brief explanation of drawings]

FIG. 1 shows a glass plate that has been sharply bent, and FIG. 2 shows a glass plate on which a conductive wire trigger and a lead circuit are formed for sharp bending. FIG. 3 shows an example of an apparatus for carrying out the method of the present invention. This is what is shown. 1 is a glass plate, 2 is a bending line, 3 is a conductive wire trigger,
Reference numeral 4 indicates a lead portion, 5 indicates a clip, 6 indicates a bending die, and 7 indicates a lead wire. Multi-purpose multi-2 meat multi-34

Claims (1)

[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 cause the conductive filament trigger to generate heat to bend the glass plate. The bent line portion of the glass plate is made conductive and the current is passed through the bent line portion, thereby heating the bent line portion of the glass plate to a temperature equal to or higher than the softening point of the glass plate, and the glass plate is heated along the bent line. In the method of sharply bending the conductive wire trigger, a lead portion electric path having a lower resistance than the conductive wire trigger is connected to the conductive wire trigger and formed around the glass plate, and a current is applied through the lead portion electric path. A unique method for sharply bending glass plates. 2. A method for sharply bending a glass plate according to claim 1, characterized in that the conductive filament trigger is made of a material that burns out after the electric current is applied and the conductive filament trigger generates heat. . 3. A method for sharply bending a glass plate according to claim 2, characterized in that a conductive wire trigger formed by printing carbon paste is used. 4. A method for sharply bending a glass plate according to claim 1, characterized in that a lead portion electric circuit formed by printing silver paste is used.