JPH06247727A - Production of plate glass formed body - Google Patents

Abstract

PURPOSE:To provide a producing method of a plate glass formed body capable of heating the narrow area of the glass at a bending line part to a temp. above softening temp. of the plate glass within an extremely short time and extremely small in thermal stress generated at the time of heating the bending line part. CONSTITUTION:This plate glass formed body is formed by drawing a bending line on a place to be bent on the plate glass with a conductive material so as to be ununiform or discontinuous along the longitudinal direction, generating arc discharge along the bending line by applying current to the bending line to heat the glass at this place to the temp. above the softening temp. of the plate glass and bending the plate glass along the bending line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sheet glass molded product for construction and general industry, and more specifically, to a single sheet glass molded product composed of a plurality of flat surfaces which are seamless in bent portions. Regarding manufacturing method.

[0002]

2. Description of the Related Art In recent years, sheet glass has been widely used for various purposes such as building exteriors and interiors or for general industry, for example, windows, show windows, wall materials, doors, partitions, display cases, aquariums, furniture and the like. ing. Conventionally, at the corners of windows, show windows, display cases, etc., two plate glasses are joined at a predetermined angle using a frame made of metal, wood, plastic, etc., and the joint between each plate glass and frame is made of silicone rubber, etc. It was adhered by the caulking material and the sealing material. However, this method has a drawback in that the appearance and transparency of the corner portion are poor due to the presence of the frame, and when a stainless steel frame or the like is used in the corner portion, the cost increases and it is not economically preferable. . On the other hand, there is a method of abutting two sheet glasses together without using the frame and joining the abutting portions with a caulking material and a sealing material such as silicone rubber. However, this method does not improve the appearance and the transparency of the corner portion, and the joined butted portion is weak in strength. In addition, since the caulking material and the sealing material have a limited weather resistance, the life of the joint is generally relatively short. As a method for eliminating the above-mentioned defects, it is known to heat a sheet of glass plate to form a bent portion having a predetermined angle. For example, a normal float plate glass is placed horizontally on the upper part of a mold having a bent portion having a predetermined angle, the whole plate glass is heated to about 500 to 580 ° C., and the bent portion is locally 700 to 750 ° C.
It is performed by heating to a certain degree and molding on a mold by gravity or other external force to make a predetermined bent portion. However, in this method, the bent portion has a relatively large radius of curvature (for example, when the plate glass has a thickness of 4 mm, the minimum radius of curvature is about 35 to 40 mm), a window, a water tank,
When it is used for a show window, a display case, etc., the object looks distorted, which is not preferable. In addition, since the vicinity of the bent portion of the plate glass is exposed to a high temperature equal to or higher than the annealing temperature over a considerable range, distortion occurs in the vicinity of the bent portion of the sheet glass after molding over a considerable range, and there is a drawback that the distortion of the flat portion is large. Was there. FIG. 6 shows an example of a cross section in the bending direction of a sheet glass having a bent portion formed by the above method. The radius of curvature at the bent portion B ₁ is about 10 times the thickness of the sheet glass, and the AB ₁ and AB ₂ portions are several times the thickness d as an intermediate portion between the flat portions A ₁ , A ₂ and the bent portion B _1. Of the optical characteristics, which are distorted over the length of, and the flat surfaces A ₁ and A ₂ are also exposed to high temperature, and as a result, the flatness before heat processing cannot be maintained, and There is a perspective distortion and a reflection distortion.

In order to solve the above-mentioned drawbacks, the present inventor has filed a patent application
In No. 4-273386, draw a bending line using a conductive material at a place to be bent on the plate glass, and electrically heat the glass of the bending line portion to a temperature equal to or higher than the softening point of the plate glass, and then bend the bending line. And a method for producing a sheet glass molded article by bending the sheet glass along the surface of the curved sheet in which the radius of curvature of the outer circumference of the curved surface in the direction perpendicular to the bent portion is remarkably small and the optical perspective distortion of each glass plane is extremely small. Has applied for a patent.

[0004]

DISCLOSURE OF THE INVENTION The present invention is, in the method for producing a flat glass molded body described above, capable of heating the glass of the bent line portion to a temperature equal to or higher than the softening point of the flat glass in an extremely short time, and It is an object of the present invention to provide a manufacturing method in which the two-dimensional internal stress generated in the entire glass sheet during heating is extremely small.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for making a sheet of glass sheet formed by a plurality of flat portions having at least one linearly bent portion, in which a portion of the sheet glass to be bent is electrically conductive. A fold line using a flexible material, wherein the fold line drawn is non-uniform or intermittent in width or thickness along its length,
Next, an electric arc is generated along the fold line by supplying power to the fold line, and the glass at the location is heated to a temperature equal to or higher than the softening point of the glazing, and then the glazing is bent along the fold line. And a method for producing a sheet glass molded body.

That is, when a bent line drawn with a conductive material is supplied with a high voltage, the glass is heated by electric resistance. Since the electric resistance is large at a portion or a break point (hereinafter simply referred to as a narrow portion) having a small width or thickness, arc discharge continuously occurs across the narrow portion. Then, the temperature of this portion becomes high, and the glass melts to form a molten spot. Conductive materials are wide (or thick) because they burn, volatilize, or diffuse into glass at high temperatures.
The amount of the conductive material at the portion of the bent line portion that is in contact with the melting spot is reduced, and as a result, arc discharge also occurs at this portion. As a result, the melting spots are finally continuous with each other to form a melting line. The melting line is 700 ° C
At the above high temperature, sodium ions are generated, the glass exhibits good conductivity, and an electric current flows on the surface of the glass. Further, with the passage of time, the conductive material on the fold line further dissipates, and the arc discharge on the glass surface disappears. At this time, the temperature of the glass surface is prevented from rising due to heat radiation, and the temperature immediately below the melting line becomes higher than that of the glass surface. The electric current flows inside the glass just below the melting line, which has a higher temperature and higher conductivity. As a result, the inside of the glass just below the melting line is heated by Joule heat and becomes in a molten state. By repeating this, an electric current also flows in the lower layer and heating occurs. As a result, it is considered that the electric current concentrates and flows in the central portion in the glass thickness direction immediately below the bending line, and the glass has a temperature distribution in which the central portion has the highest temperature. In actual visual observation, it can be seen that the glass melts rapidly from the surface toward the center. Regardless of the details of the phenomenon, in any case, the glass penetrates the front and back sides along the fold line and becomes extremely locally melted. The above phenomenon is completed in an extremely short time (for example, several seconds to 30 seconds) (for example, 5 seconds is sufficient for glass having a thickness of 5 mm, and 10 seconds is such that the glass at the bent line portion hangs down due to gravity). . Therefore, there is little heat transfer in the glass plane direction, and the vicinity of the bent line portion does not rise to the softening point. Moreover, the forming is as if two sheet glasses were welded. Therefore, it is possible to manufacture a plate glass molded body in which the bent portion is very sharp and the flatness of the flat portion is extremely good up to the vicinity of the bent portion in an extremely short time.

First, in the method for producing a sheet glass molded body of the present invention, a known material can be used as the conductive material used for drawing the bending line. Examples of the conductive material include carbon, graphite or silver, copper, nickel, chromium and silicon carbide. As a carbon-based conductive paint, Bunny Height (F
-525W-1) and the like, and as the silver-based conductive paint, H9100 manufactured by Hokuriku Paint Co., Ltd. or D-1230 (modified) manufactured by Fujikura Kasei Co., Ltd. can be mentioned. It can be appropriately selected from these, depending on the size and thickness of the plate glass, the operating voltage, the resistance of the bent line, the adhesiveness to the glass, the coloring of the glass due to the diffusion of metal ions, and the like. When carbon or graphite is used, it is easy to control the electric power,
Further, it is convenient because it can be completely burned and removed by blowing oxygen after the heating step (for example, in the bending step).

The paste-like conductive paint is applied on the surface of the plate glass by screen printing, letterpress printing, spraying or transfer. The metal or alloy can be applied by metal spraying, CVD, or pyrolytic methods. In the metal spraying method, a mask having slits corresponding to bending lines is placed on a glass plate, the above metal is used as a conductive material, the metal is melted by an electric arc or flame, and blown from a nozzle with compressed air. Then, spray the plate glass surface and draw a bending line. In any of the above methods, the drawn fold line is in close contact with the surface of the plate glass and can be accurately printed at a predetermined location. Screen printing and metal spraying are preferred because of their accuracy and simplicity. The number of the folding lines is the same as the number of bent portions of the flat glass molded body required as a product, and at least one is drawn on one flat glass. When a plurality of folding lines are drawn, they may be drawn in parallel or non-parallel to each other depending on the desired product shape. An example of the shape of the product is shown in FIG.

As a folding line of the present invention, for example, FIG.
The items shown in are listed. In the figure, dimensions are in mm. The width of the wide portion of the fold line does not largely depend on the thickness of the plate glass, and is preferably 0.5 to 5 mm, particularly preferably 1 to 3 mm. If the width of the wide portion is less than 0.5 mm, heating with necessary electric power cannot be performed, which is not preferable. Further, when it exceeds 5 mm, the range of the plate glass heated near the softening point is too wide and the bent portion is not sharp, which is not preferable. The width of the narrow portion of the folding line is preferably 1 mm or less, and particularly preferably 0.5 mm or less. If the width of the narrow portion exceeds 1 mm, arc discharge hardly occurs, which is not preferable. The folding line is preferably 0.1 to 2 mm, particularly preferably 0.
It may be intermittent at intervals of 5 to 1.0 mm. If the distance exceeds 2 mm, arc discharge is unlikely to occur, which is not preferable. Further, the folding line is preferably a repeating pattern of a wide portion and a narrow portion or a repeating portion which is intermittent, and has a length of 0.3 to 10 mm, particularly preferably a repeating pattern having a length of 1 to 3 mm. is there.
If the repetition exceeds 10 mm, the time required for heating becomes long, which is not preferable, and if it is less than 0.3 mm, it is difficult to form a bending line with an accurate shape, which is not preferable. In addition, the thickness of the bent line depends on the type of conductive material,
It depends on the method used to draw the folding line, but it is sufficient if the glass can be stably heated to a predetermined temperature for a predetermined time, preferably 0.1 to several 100 μm, for example, 10 to 100 μm in the screen printing method,
In the thermal spraying method, the thickness is preferably 30 to 300 μm. Further, the bending line may have a changed thickness. The thickness of the bent line having a large thickness is preferably 10 to 50 μm.
m, and the thickness of the small portion is preferably 5 to 15 μm
Is. The width of the folding line is preferably 0.5 to 5 m
m, and the repetition of the thick part and the small part is
It is preferably a repeating pattern having a length of 0.3 to 10 mm. For example, the width is 1.0 mm, the thickness of the thick portion is 30 μm, the thickness of the small portion is 10 μm, and the repetition of the thick portion and the small portion is 1 mm.
The bending line is the length of.

The folding line may be drawn on one side, both sides, one side and both end sides of the plate glass, or a loop connecting the both sides and both end sides. Generally, a fold line is drawn only on a surface that is an outer side when bending a sheet glass. When the plate glass is thick, it is preferable to draw folding lines on both sides.

The method described below is preferably used as a method for supplying power to the bent line drawn on the plate glass. That is, a method in which a solid electrode having an appropriate shape is brought into contact with the bent line at the edge of the plate glass to supply power, and a conductive high temperature gas frame that generates lithium ions or the like is brought into contact with the bent line at the edge of the plate glass to supply power through the frame Is the way to do it. The power source used in the above method is an AC power source of 50 or 60 Hz, which is commonly used for commercial purposes, and 10
A high frequency power source or a direct current power source of 0 KHz to 50 MHz is used, and the voltage is a voltage sufficient to cause arc discharge, preferably several thousand volts to 20,000 volts, and the current is preferably 0.5 to 2 It is about ampere.
Although any of the above types of power sources can be used in the method using the solid electrode, a high frequency power source is preferable in the method using the conductive high temperature gas flame. The selection of the type of power source to be used is determined in consideration of the type of the method for supplying power to the bent line portion, the size of the plate glass, and the like.

Further, the temperature control is performed by current, voltage, energization time, thickness and size of the glass sheet to be used, widths of wide and narrow bend lines, intervals between discontinuous bend lines and bend lines. Considering the length of the repeating pattern, the bending speed of the plate glass, the final bending angle, etc., it is preferably carried out by controlling the current and the energization time. Since the control factor includes a large number of parameters as described above, temperature control is preferably performed by computer control, and a desired heating temperature can be achieved very easily. Usually, heating for several tens to several hundreds of W per 10 cm of bending line length can be performed by energizing for several seconds to 30 seconds, which is sufficient. Therefore, the heating time was shortened to about 1/2 to 1/20 as compared with the method of the above-mentioned Japanese Patent Application No. 4-273386 (heating took 20 minutes in the conventional bent glass manufacturing method). For example, in the case of a plate glass having a thickness of 3 mm, a heating time of about 5 seconds is possible. The method of the present invention is particularly effective in the case of thick glass.

By the above heating method, the bent line portion drawn on the plate glass is heated to a predetermined temperature. The temperature is
The temperature of the plate glass of the bent line portion is equal to or higher than the softening point of the plate glass, and particularly preferably the softening point to the softening point plus 140 ° C.
Is the range. When the temperature exceeds the above range, the flat portion near the bending line after bending is distorted, and it is not preferable from the economical viewpoint. Here, the softening point of the plate glass means a temperature at which the glass is deformed by its own weight, and generally the viscosity of the glass corresponds to about 10 ⁸ poise. In the method of the present invention (normally about 740 ° C. for float glass), since heating occurs in an extremely narrow width of the glass sheet, the two-dimensional stress that occurs is small and lasts only a short time, so there is no risk of the glass sheet breaking. Less. This can be understood from the fact that if the glass is melted with an infinitesimal width, and the immediate vicinity thereof is room temperature, the glass will never break.

In order to achieve the method of the present invention more preferably, the whole plate glass is heated to a temperature preferably lower than the annealing point of the plate glass, more preferably the annealing point of the plate glass, prior to the heating of the bent line portion. 0 to 200 ° C. lower, particularly preferably 50 to 100 from the annealing point of the plate glass.
It is preferable to heat at a temperature lower by 0 ° C. substantially uniformly. By simply performing uniform heating at a relatively low temperature in this way, in the case of extremely localized heating due to later arc discharge,
The two-dimensional internal stress generated in the plate glass is extremely small. Therefore, it is possible to safely prevent the plate glass from cracking by the above uniform heating. Here, the annealing point of the plate glass generally means a temperature at which the viscosity of the glass reaches about 10 ¹³ poise.
A known method can be used as the above heating method, for example, a method of heating the plate glass substantially uniformly by inserting it into an electric furnace in which the whole plate glass is controlled to a constant temperature can be used.
Heating can be performed easily.

In the method of the present invention, the heating of the sheet glass by arc discharge is usually performed in the air, but it is not limited to this.

The plate glass used in the present invention is one used for construction or general industry. The plate glass may be one produced by a known method, however, since it is necessary that the flat portion of the plate glass formed by the method of the present invention has no distortion, a float plate glass formed on molten tin metal is used. Preference is given to using. The plate thickness, shape and dimensions of the plate glass used are determined according to the purpose,
There is no particular limitation. There is also no particular limitation on its composition,
Plate glass having various softening points such as commonly used soda-lime glass, borosilicate glass, and high-strength crystallized glass can be used. The types of the plate glass include ordinary plate glass, polished plate glass and shaped plate glass. Further, the above plate glass may be subjected to various surface treatments such as heat ray reflective coating, non-reflective coating, specific pattern printing and surface etching.

In the method of the present invention, the method of bending the flat glass sheet at a predetermined angle along the fold line is performed by an appropriately designed glass sheet holding mechanism. At that time, the bending speed, the bending external force and the final bending angle are precisely controlled through the holding mechanism. This prevents the occurrence of cracks in the bent portion, and makes it possible to obtain a predetermined cross-sectional shape and wall thickness of the bent portion. As the plate glass holding mechanism,
For example, there is a device that sandwiches plate glass with a plate attached to an arm in a sandwich shape and moves the arm by power to bend the plate glass at a predetermined angle. Thereby, the internal angle between two adjacent planes is preferably set to 60 to 160 degrees. The bending operation can be completed within a very short time, and usually 1 to 5 minutes is preferable.

The conductive material having the above-mentioned bending line is
Usually, it is removed after the above thermoforming. Many of the components of the conductive material gradually burn or scatter during heating, and may remain little after the completion of molding. From this point, a carbon-based conductive paint is preferable. Depending on the type of conductive material or the thickness thereof, it may remain completely on the glass surface due to complete burning. In such a case, oxygen can be blown and completely burned to be removed after the heat molding, or the glass can be removed by an appropriate mechanical method or chemical method such as polishing after cooling. In the case of a metal-based conductive material, the metal component often diffuses into the glass. From a design point of view, if you want to leave a line made of conductive material on the finished sheet glass molded body,
The fold line can be drawn by using a conductive material having a predetermined composition so that a desired color tone appears.

The glass after heat-molding is post-treated in the same manner as in the prior art, and can be subjected to, for example, slow cooling or rapid cooling to obtain a slowly cooled product, a strengthened product or a double strengthened product. Also a heat ray reflective coat,
Various surface treatments such as anti-reflection coating, printing of a specific pattern, and etching of the surface can also be performed.

In one sheet glass molded body having a plurality of flat portions having at least one linear bending portion manufactured by the method of the present invention, the curvature of the outer circumference of the curved surface in the direction perpendicular to the bending portion. The radius is 1 to 4 times the thickness of the flat glass in the flat portion, preferably 1
~ 3 times. If the radius of curvature exceeds four times the thickness of the glass sheet, the distortion of the see-through object becomes large at the bent portion, which is not preferable, and if it is significant, the see-through object looks enlarged. On the other hand, if the radius of curvature is less than 1 time,
It is not preferable in terms of safety for humans because the strength of the corner portion is small. Further, there may be a transition region which is slightly deformed and loses flatness between the bent portion and the flat portion, and the width of the transition region is preferably 6 times or less the thickness of the sheet glass, and particularly, It is preferably 2 times or less. If the width exceeds twice, the object seen through in the plane portion near the bent portion is distorted, which is not preferable. The flat glass surface of the flat portion of the flat glass molded body is substantially flat. For example, in the case of a plate glass molded body using a float plate glass, the flatness of the float plate glass before bending is maintained as it is.

FIG. 2 shows an example of a cross section in the bending direction of the bent portion of the sheet glass molded product according to the present invention. R in the figure is the radius of curvature according to the present invention. Points P and Q are the points where the curved surface begins. Outside the bending points P and Q of the molded sheet glass of the present invention, a portion having a relatively poor optical property, which is apparently flat but is slightly deformed to impair the flatness, that is, a transition region S.
May exist. In a conventional flat glass having a bent portion, the radius of curvature is extremely large as shown in FIG. 6, the boundary between the flat portion and the bent portion is not clear, and the glass is slightly deformed in the middle from the flat portion to the bent portion. Then, there is a transition region over a considerable length which impairs the planarity.
On the other hand, the flat glass molding of the present invention is remarkably different.

The above-mentioned sheet glass molded article refers to one having at least one corner portion, and examples thereof include various molded articles as shown in FIG.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[0024]

Example 1 A square float plate glass (soda lime glass, softening point 740) having a length and width of 1000 mm and a thickness of 5 mm
C., a slow cooling point of 540.degree. C.), using a carbon-based conductive material (trademark Bunny Height F-525W-1, manufactured by Nippon Graphite Trading Co., Ltd.), bend it to have a shape shown in I of FIG. Lines were drawn on one side of the glazing using screen printing with a constant thickness of 20 μm. A solid electrode was placed at the end of the fold line.

Then, the plate glass was sandwiched by the plates attached to the arms by a plate glass holding mechanism, and the plate glass was uniformly heated to 470 ° C. in an electric furnace. Subsequently, an alternating current of 50 Hz was applied to the bent line in the power pattern shown in FIG. After energization for 60 seconds (d), the plate glass of the bent line portion reached 800 ° C. Immediately, the heating power was reduced and the plate glass was bent using the above plate glass holding mechanism, and the two flat surfaces became perpendicular to each other in about 60 seconds. The temperature distribution of the plate glass along the line X ₁ X ₂ in the direction perpendicular to the bending line at the time of the above energization for 60 seconds is shown in FIG.
It was as shown in. 15 on each of the left and right of the fold line L
The range outside mm points p ₁ and p ₂ was 550 ° C. or lower. After molding as described above, the plate glass molded body was manufactured by slowly cooling.

The radius of curvature of the outer circumference of the curved surface in the direction perpendicular to the bent portion of the manufactured sheet glass molded body is 6 mm, which is 1.2 times the thickness of the sheet glass in the flat portion, and is slightly deformed to provide flatness. The lost transition region was not seen in the plate glass portion in the range of 10 mm or more on the left and right in the direction perpendicular to the bending line. Further, the flat portion of the plate glass molded body,
The original flatness of the float glass sheet used in the method of the present invention was maintained as it was, and no increase in optical perspective distortion and reflection distortion was observed.

As described above, when the method of the present invention is used, it is possible to heat the plate glass of the bent line portion to a temperature above the softening point in a narrow range in an extremely short time. In addition, the bent portion of the manufactured sheet glass molded body was very sharp, and the flat portion thereof had no distortion and had excellent transparency.

[0028]

According to the present invention, the plate glass of the bent line portion can be heated to a temperature equal to or higher than the softening point in a narrow range in an extremely short time. Further, since the thermal stress generated when the bent line portion is heated is extremely small, it is possible to prevent the glass from cracking. Therefore, the method of the present invention is simple and economical. Further, it is possible to obtain a sheet glass molded product having a bent portion, in which the radius of curvature of the outer circumference of the curved surface in the direction perpendicular to the bent portion is extremely small, and the optical perspective distortion and the reflection distortion of the flat surface portion are extremely small.

[Brief description of drawings]

FIG. 1 is an example of a fold line used in the method of the present invention.

FIG. 2 is an example of a sectional view in a bending direction of a bent portion of a sheet glass molded body manufactured by the method of the present invention.

FIG. 3 is an example of a sheet glass molded body manufactured by the method of the present invention.

FIG. 4 is an electric power pattern when the glass of the bent line portion is heated in Example 1 of the present invention.

FIG. 5 is a temperature distribution of plate glass in a direction perpendicular to the bending line when the glass in the bending line portion is heated in Example 1 of the present invention.

FIG. 6 is an example of a sectional view in the bending direction of a bent sheet glass manufactured by a conventional method.

[Explanation of symbols]

R: radius of curvature of the outer circumference of the curved surface in the direction perpendicular to the bent portion S: transition area P, Q: starting point of the bent portion d: thickness of the sheet glass G: sheet glass L: bending lines A ₁ , A ₂ : plane portion AB ₁ , AB ₂ : Transition area between plane portions A ₁ and A ₂ and bent portion B ₁ B ₁ : Bent portion

Claims (5)

[Claims] 1. A method of producing a single sheet glass molded body having a plurality of flat portions having at least one linearly bent portion, wherein a bending line is formed at a place to be bent on the sheet glass by using a conductive material. Draw, where the drawn fold line is non-uniform or intermittent in width or thickness along its length, and then arc discharge along the fold line by powering the fold line. And heating the glass at the location to a temperature equal to or higher than the softening point of the sheet glass, and then bending the sheet glass along the bending line. 2. The width of the portion where the bending line is wide is 0.5.
The manufacturing method according to claim 1, wherein the width of the narrow portion is -5 mm and the width of the narrow portion is 1 mm or less. 3. The method according to claim 1, wherein the folding lines are intermittent at intervals of 0.1 to 2 mm. 4. The fold line has a length of 0.3 to 0.5 along the longitudinal direction.
A repetitive pattern having a length of 10 mm.
The method according to any one of 3 above. 5. The method according to claim 1, wherein the whole plate glass is heated substantially uniformly below the annealing point of the plate glass, and then the bent line portion is heated according to the above.