JPS6021824A - Process for sharply bending glass plate - Google Patents

Abstract

PURPOSE:To enable bending work of a glass plate with a sharp angle leaving no trace of heater filament by providing a heater filament along a bending line on a glass plate interposing a layer of parting agent, and laying a heat resistant sheet on the heater filament. CONSTITUTION:A heater filament 14 is provided in accompany with a bending line 11 along which a glass plate 10 is to be bent with a sharp angle. A layer of a parting agent 12 is formed on the bending part of the glass plate 10, contacting with the heater filament 14 so as to prevent generation of trace of the heater filament 14 due to melting and sticking of the filament 14 to the glass plate 10 when electric current is passed through the heater filament 14. A sheet 13 of heat resistant fiber is laid on the glass plate 10 to cover the part of the bending line attended by the heater filament 14 and to hold down the heater filament 14. By this constitution, distribution of the heater filament along the bending line 11 for bending the glass plate 10 with a sharp angle is secured and generation of shift of the position of the heater filament 14 in a bending work is prevented; thus, desirable bending work is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for sharply bending glass sheets.

As a method of sharply bending a glass plate, a heater wire is arranged at a predetermined distance from the glass plate surface on the bending line where the glass plate is to be sharply bent, and the heater wire is heated by electricity to bend the glass plate along the bending line. A method is known in which the glass plate is sharply bent along the bending line by heating the portion to a temperature equal to or higher than the softening point of the glass plate. In this method, since the heater filaments do not come into contact with the surface of the glass plate, no traces of the heater filaments remain on the curved portion of the glass plate, so the appearance is unsophisticated. but.

Therefore, if the bending line where you want to sharply bend the glass plate is curved or bent, when you use the above method to sharply bend the glass plate, it is necessary to wire the heater wire along the bending line. However, it takes time and cost to manufacture a jig to maintain the wiring state during bending, and since the glass plate and the heater wire are spaced apart from each other by a predetermined distance, the glass plate There was a drawback that it became difficult to locally heat only the bent line portion, and it was impossible to bend the glass plate sharply, for example, to make the curvature of the bent portion less than 30R.

The present invention improves these drawbacks, allows easy bending along curved or curved lines, and allows the glass plate to be bent sharply to a curvature of 30R or less on the outer surface side of the bent portion. It is possible to bend the glass plate in such a way that no trace of the heater stripes remains on the bending line of the glass plate.
It was invented as a result of studies with the aim of providing a method for bending the glass plate.The gist of the invention is to arrange heater wires along the curved line where the glass plate is to be bent sharply, and to energize the heater wires. In the method of sharply bending the glass plate along the bending line by heating the bending line part of the glass plate to a temperature similar to that of softening the glass plate, 1. A glass characterized in that heater stripes are arranged along the bending line with a release agent layer interposed therebetween, and a heat-resistant fiber sheet is overlaid on the heater stripes to suppress the heater stripes. It concerns a method of sharply bending a plate.

The present invention will be explained in more detail below.

1 and 3 are perspective views of a sharply bent glass sheet according to the invention, FIG. 2 shows the glass sheet cut to produce the glass sheet of FIG. 1, and FIG. The figure shows a glass plate cut to produce the glass plate of FIG.

In the figure, 1 indicates a glass plate to be bent, 2 indicates a glass temporary formed body which has been bent, and 3 indicates a bending line for sharply bending the glass plate.

When sharply bending a glass plate by the method of the present invention, the glass plate is cut into a predetermined size and shape. The bending line that tries to sharply bend this cut glass plate,
A heater strip is arranged along the bending line. A mold release agent is applied to the curved portion of the glass plate where the heater line comes into contact with the heater line to prevent the heater line from welding to the glass plate and leaving traces of the heater line when the heater line is energized and heated. It is formed. As this mold release agent, one is used that maintains its performance even at the heating temperature of the heater wire, for example, 800°C to 1000°C. For example, as a mold release agent,
Calcium carbonate, heavy metal, boron nitride.

Heat-resistant inorganic materials such as carbon can be preferably used.

On the surface of the glass plate where the heater stripes are arranged along the desired sharp bending line, a heat-resistant fiber sheet is placed over the glass plate surface, covering the bending line where the heater stripes are arranged. Attach the filament 1111. This ensures that the heater filament is wired along the sharp bending line of the glass plate, prevents misalignment of the heater filament during bending, and enables the desired bending process. can be done.

This heat-resistant fiber sheet has sufficient heat resistance to the heating temperature of the heater strip, for example 800°C to 100°C, and has flexibility that follows the bending process of glass. things are used. For example, heat-resistant ceramic fibers made of quartz glass fiber, various glass fibers, asbestos, etc. can be used. Among them, quartz glass fiber has sufficient heat resistance and excellent chemical and physical stability, so it is most suitable as the heat-resistant fiber sheet used in the present invention.

In the present invention, the heat-resistant fiber sheets that are stacked to suppress heater filaments arranged along the bending line of the glass plate to be bent once need only cover at least most of the bending line of the glass plate. The sheet 1- may be sized to cover only the bent line portion of the glass plate, or may be sized to cover the entire glass plate including the bent line portion to be bent.

・Since the heater strips are usually placed on the side that forms the internal angle of the glass plate that is to be bent sharply, the thickness of the heat-resistant fiber sheet must be adjusted so that it can be bent sharply without causing any trouble. 50 Including ease 0.2mm~2
ITII+ grade is the most practical. Of course, the curvature is 3O
If the radius is larger than R, the bending process can be performed at the same time and in the same way as the bending process, and it will not cause any defects to the glass plate, so it is optimal.

Such a heat-resistant fiber sheet is arranged on the side that forms the inner corner of the glass plate where the heater filament is normally bent sharply, so in the case of a method in which the shaft of the glass plate is sharply bent upwards by bending under its own weight, the bending process is difficult. A heat-resistant fiber sheet is placed on the second side of the glass plate to be processed, and in the case of a method in which the shaft of the glass plate is sharply bent downward by self-weight bending, the glass plate to be bent is A heat-resistant fiber sheet will be placed on the bottom side of the.

Furthermore, a cover glass plate can be further stacked on top of the heat-resistant fiber sheet 1- to suppress the heat-resistant fiber sheet 1-, thereby further reliably preventing the heater filament from shifting from a predetermined position. Similar to the heat-resistant fiber sheet 1-, the cover glass plate placed on top of the heat-resistant fiber sheet 1- only needs to cover at least most of the bending line of the glass plate. The glass plate may be sized to cover only the line portion, or may be sized to cover the entire glass plate including the curved line portion to be bent. Since the heater wires are placed on the side that forms the inner corner of the glass plate that is to be bent sharply, the thickness of the cover glass plate is set so that it does not cause any trouble when bent sharply, such as when bending a glass plate. It is preferable that it be thin so that it can be bent sharply with a curvature of 30R or less.

The specific thickness of the board is 1 to 2, including ease of handling.
The side degree is the most practical. Of course, if the curvature is greater than 3OR, a plate thicker than 2+11TI can be used.

A mold release agent layer is formed on the desired bending line portion of the glass plate to be bent, a heater filament is arranged on it so as to match the bending line, and a heat-resistant fiber sheet 1- is layered on top of it. The assembly, in which the heater filaments are suppressed and, if necessary, a cover glass is layered on top of a heat-resistant fiber sheet, is made of a self-weight material with a contour designed to obtain a glass plate molded body of a predetermined shape, for example. Place the glass plate on a bending mold for bending, put it into a heating furnace, and heat the entire glass plate to a temperature above its strain point and below its softening point, for example 45
Heat to a temperature of about 0°C to 600°C. If the glass plate is heated to a temperature higher than 600° C., there is a risk that the glass plate will undergo undesirable deformation such as doubling. On the other hand, if the temperature is lower than 450° C., the temperature will become non-uniform during subsequent heating by the heater wire, and there is a risk of thermal cracking, which is not preferable.

Note that if complicated bending is required and it is advantageous to heat the glass plate to a higher temperature, the glass plate can be heated to a temperature higher than 650°C.

When the glass plate reaches the above-mentioned temperature, a voltage is applied to the heater filaments to raise the temperature of the heater filaments to 650°C or higher, preferably 75°C.
The glass plate is electrically heated to a temperature of 0°C to 800°C, and the curved line portion of the glass plate that contacts the heater filament via a mold release agent is locally heated to a temperature near the softening point of the glass plate or higher, for example 680°C to 75°C.
Heat to a temperature of about 0°C. When the bending line portion of the glass plate reaches a temperature near or above the softening point of the glass plate, the glass plate is sharply bent into a predetermined shape by a self-weight bending mechanism.

The heater wire used in the present invention is heated to 650°C to 850°C, preferably 750°C.
A conductive material that generates heat at a temperature of about 800° C. and is stable above this temperature is selected. The shape of the heater filaments is such that the heater filaments are arranged along the bending line of the glass plate to be bent, and at the same time, even if they are suppressed by the cover glass plate, the heater filaments are arranged along the bending line of the glass plate. The material should be ribbon-shaped or linear and have zero thickness to prevent it from digging into the heater or leaving traces of the heater stripes.
, 51+wn or less, preferably 0.05 m to 0.2 river.

The materials are nickel-chromium alloy, iron-
Chrome alloy, stainless steel, tantalum.

It is best to be made of platinum, molybdenum, etc.

In the example described in ``1'', an example was explained in which the self-weight bending method was applied as a method for sharply bending a glass plate along a bending line. Glass plate bending methods such as can also be used in the same manner.

After the bending process, the glass plate sharply bent by the method of the present invention can be subjected to a strengthening treatment or an annealing treatment, if necessary.

Also, in the present invention, it is used to hide optical distortion at the bent line portion of a sharply bent glass plate.

Alternatively, in order to make the traces of the heater filaments less noticeable, a colored band can be formed on the bent line portion of the glass plate. This colored band may be placed on the inside of the sharply bent corner of the glass, or it may be placed on the outside. Further, this colored band may be formed before the glass plate is sharply bent, or may be formed after this bending process is performed.

A typical example of this colored band is Ceramic Chikara Rafritz 1.
−, and when using this, it is necessary to

When printing a strip on the inside or outside of the bending line of a glass plate and forming a ceramic rough frit 1- on the inside of the bending line, a release agent is then applied to the surface, and the process as described above is applied. Bending the glass plate according to the method C, and baking the ceramic frit 1 to the curved portion of the glass plate.

Next, embodiments of the present invention will be described according to FIGS. 5 to 10.

Im glass plate 10 (vertical dimension: 500aus horizontal dimension: 3
A calcium carbonate powder layer is formed as a template agent layer 12 along the sharply bent bent line 11 (00+nm),
Then, as shown in FIG. 6, a ribbon-shaped nichrome heater wire with a thickness of O-21111n and a length of 350 m is placed on top of it along the bending line 11.
, 4 (no=1.15Ω/n+), and on the upper surface of the glass plate 10 on which the heater stripes 14 are arranged, silica glass (trade name of quartz glass fiber of Japan Inorganic Fibers ■) of the same size as the glass plate is placed. , thickness in+m) were stacked on top of each other to press down and hold the heater filaments 14. The assembly prepared in this way is placed on a bending die 15 for self-weight bending as shown in FIG. By applying 1.80W of power to the
The bent portion of the glass plate is heated to 0°C using the heater wire to soften it to 680°C, and the moment of the counterweight 16 attached to the bent part of the gravity bending mold 15 is used to bend the glass plate. was bent sharply along its bending line. The bending die is a self-weight bending die having a ring whose upper surface is the forming surface as shown in Fig. 5, and the ring has a movable part 1G in the part corresponding to the oil part of the glass plate. The part corresponding to :tJ in the middle part of the glass plate 10 is the non-movable part 17, and the glass plate is located on the line connecting the pair of hinges connecting the movable part 16 and the non-movable part 17. The Q used is designed so that the bending lines of the parts coincide with each other, and the movable part 16 and the non-movable part 17 form an angle of 85 degrees.

After bending the glass plate 10, it was taken out from the heating furnace, the heat-resistant fiber sheet 1- was removed, and air cooling reinforcement processing was performed.

The glass plate that is sharply bent into a U shape in this way has an angle of 85° between the axis and the center of the glass plate, and the inner curvature of the bent part is 5R. No traces of heater streaks were left on the surface, and the appearance was good.

Example 2 Soda lime cut into 9 dimensions as shown in Figure 8.
Glass plate 10 (Fi thickness: 5 +nn+, a =
530 na.

b == 400nwn, c = 150'u+++
+, d = 500nnn) along the sharply bent bending line 11, as shown in FIG. Thickness along 0, 2 urn, fil
4 m+n, length 1300nIIll ribbon-shaped heater wire made of nichrome (Ro=1.i5Ω/m)
glass with heater stripes 14 arranged +yi
A heat-resistant fiber sheet 1 made of the same silicone glass as in Example 1 and having the same dimensions as the glass plate is layered on the top surface of the glass plate 13 to suppress the heater wires, and then the assembled assembly is bent as shown in FIG. Place the heat-resistant fiber sheet 1 on the mold with the heat-resistant fiber sheet 1- facing downward, place it in a heating furnace and heat the entire glass plate to 500°C, then apply 600W of power to the heater wire. The heater filament is heated to 700°C, and the bent line 11 portion of the glass plate 10 is heated to 650°C by the heater filament.
The oil portion of the glass plate 10 was made to hang downward at a right angle.

Next, after performing slow cooling treatment, the cover glass plate was removed,
A sharply bent glass plate as shown in FIG. 1 was obtained. The angle between the axis and the center of this glass plate is 80°, and the inner curvature of this bent part is ]OR, and there are no traces of heater filaments left on the bent part of the glass plate, and the appearance is good. Met.

As described above, according to the present invention, the heater filaments are suppressed by a heat-resistant fiber sheet and, if necessary, by a temporary cover glass. Even when the glass plate is sharply bent into a curved line, a combination of curved and straight lines, or an S-shaped bending line, the wiring position of the heater wire should be adjusted along the bending line of the glass plate. The heater wire can be held securely without shifting until the sharp bending process is completed, making it possible to accurately bend the heater wire into a predetermined shape. Since the heater wire is electrically heated to locally heat the curved portion of the glass plate, the curvature of the inner and outer portions of the curved portion of the glass plate can be reduced. For example, according to the present invention, it is possible to reduce the curvature of the bent portion of the glass plate to 5R. Moreover, since a layer of female molding agent is formed between the bending line part of the glass plate to be bent and the heater filament, there is no trace of the heater filament left on the bending part of the glass plate, resulting in an excellent appearance. Can be bent.

In addition, as a method for sharply bending a glass plate, conductive frit paste such as silver paste is printed in a line along the bending line where the glass plate is to be bent sharply, and this printed line is applied to a local part of the bending line of the glass plate. A method of using it as an electric heating heater for heating is also known, but for example, in the case of chain paste (1), the melting point of silver is about 960°C, and the desired heat generation can be obtained and the resistance value is low. Thickness is usually 2
Since it is made as thin as 0μ to 30μ, it has the disadvantage that it is easy to cut and high power cannot be applied.Therefore, there is a limit to local heating of the curved portion of the glass plate, so the curvature of the curved portion is less than 15R. It is difficult to lower it. On the other hand, since the method of the present invention uses heater wires, it is possible to locally heat the curved portion of the glass plate to a higher temperature than in the method using conductive Norit paste described in 1. For example, it is possible to bend sharply up to a curvature of 5 degrees. Furthermore, in the method using the conductive fritz 1-paste described above, the printed lines remain on the bent parts of the glass plate after bending, but in the case of the present invention, no printed lines remain on the bent parts of the glass plate. There is also an advantage.

[Brief explanation of the drawing]

1 and 3 are perspective views of a glass sheet that has been sharply bent according to the present invention, FIG. 2 is a plan view of a glass sheet cut to form the glass sheet of FIG. 1, and FIG. FIG. 2 is a plan view of a glass plate cut to form the glass plate, and FIGS. 5 to 10 are explanatory diagrams for explaining the present invention in detail. 1.10? Glass plate, 3, 1.1; Bending line, 12; Release agent layer, 13; Heat-resistant fiber sheet 1-114; Heater filament 7, t) A 77A B) 321 1---112

Claims (6)

[Claims] (1) A heater wire is arranged along the curved line where the glass plate is to be bent sharply, and the heater wire is energized and heated to heat the bent line portion of the glass plate to a temperature higher than the softening point of the glass plate. = L In the method of sharply bending a glass plate along the bending line, a heater strip is arranged on the surface of the glass plate along the bending line of the glass plate with a release agent layer interposed therebetween; A method for sharply bending a glass plate, which comprises overlaying a heat-resistant fiber sheet 1 on the heater filaments to suppress the heater filaments. (2) Heat-resistant fiber sheet is heat-resistant ceramic fiber sheet 1
A method for sharply bending a glass plate according to claim 1, characterized in that: -. (3) The method for sharply bending a glass plate according to claim 1, wherein the heat-resistant fiber sheet is flexible. (4) The method for sharply bending a glass plate according to claim 1, wherein the heat-resistant ceramic fiber sheet is a quartz glass fiber sheet. (5) Claim 1, characterized in that a ceramic color frit layer is formed along the curved line of the glass plate.
A method for sharply bending a glass plate as described in Section 1. (6) A method for sharply bending a glass plate according to claim 1, characterized in that a cover glass plate is further stacked on the heat-resistant fiber sheet stacked on the heater filament.