JP5850332B2 - Thin glass forming apparatus and method - Google Patents

Description

  The present invention relates to an improvement in technology for producing thin glass by an overflow downdraw method.

  As is well known, thin glass used in various fields as represented by glass substrates for flat panel displays (FPD) such as liquid crystal displays, plasma displays, organic EL displays, and cover glasses for organic EL lighting. In some cases, strict product quality against surface defects and waviness is required.

  Therefore, as a method for producing this type of thin glass, an overflow down draw method may be used in order to obtain a smooth and defect-free glass surface. In this method, molten glass is poured into the overflow groove at the top of the molding apparatus, and the molten glass overflowing on both sides is fused and integrated at the lower end of the molding apparatus while flowing down along both outer side surfaces of the molding apparatus. One sheet glass (also referred to as a glass ribbon) is continuously formed while the fused and fused molten glass is drawn downward.

  However, the molten glass shrinks in the width direction under the influence of gravity and surface tension in the process of flowing the molten glass along the outer surface portion of the forming apparatus, and the width direction dimension of the thin glass to be formed is reduced. There's a problem. Further, when the molten glass shrinks in this way, there is a problem that ear portions (non-product portions) that are relatively thick are formed at both end portions in the width direction of the formed thin plate glass.

  Such an ear part not only reduces the area of the product part in which the thickness of the center part in the width direction of the formed thin glass is constant, but also causes an adverse effect when the molten glass is stretched below the molding apparatus. obtain.

  Therefore, in Patent Document 1, it is proposed to partially change the shape of the outer surface portion of the molding device in order to prevent the molten glass from shrinking in the width direction in the process of flowing through the outer surface portion of the molding device. That is, in this document, a triangular pyramid-shaped web surface portion in which a perpendicular to the surface is oriented horizontally is formed at both ends in the width direction of the molding surface portion of a molding apparatus (molding wedge-shaped body) having a substantially wedge-shaped outer surface. It is disclosed that an extended surface portion having an inverted triangular pyramid shape in which a perpendicular to the surface is directed downward is provided below the web surface portion. And by such a web surface part and an extended surface part, without increasing the length in the width direction of the molding apparatus itself, the width of the thin glass stretched from the molding apparatus (a product part in which the sheet thickness is mainly constant). To increase the width).

JP 2008-531452 A

  However, in patent document 1, since the perpendicular to the web surface portion is horizontal, the lower end portion of the web surface portion cannot be converged, and there is a need to additionally attach the extended surface portion. That is, there is a problem that the structure of the molding apparatus becomes complicated because the part that regulates the shrinkage of the molten glass and the part that fuses and integrates the molten glass are composed of separate members.

  And in order to converge the lower end part of an extended surface part, the perpendicular with respect to an extended surface part is made to face diagonally downward unlike the perpendicular with respect to a web surface part. For this reason, when the molten glass reaches the extended surface portion from the web surface portion, the flow direction is greatly changed, and the flow of the molten glass is easily disturbed. Therefore, the thickness distribution of the molten glass at the lower end portion of the extended surface portion becomes non-uniform, and a thin portion and a thick portion may be locally generated at the width direction end portion of the molten glass. If uneven thickness occurs in this way, as a result, it is not only possible to increase the width direction dimension of the product portion of the thin glass, but it also causes the thin glass to be broken during molding or cutting, which is a serious problem. Become.

  The present invention is technically capable of reliably increasing the width-direction dimension of a product portion of a thin glass sheet to be formed while suppressing uneven thickness of both ends in the width direction of the molten glass without complicating a forming apparatus. Let it be an issue.

  In order to solve the above problems, the present invention allows molten glass to flow down along both outer surface portions, and is integrated and integrated at a converging portion formed at the lower end of the opposite inclined surface portions of both outer surface portions. A sheet glass forming apparatus that continuously forms a sheet of thin glass and has a flow restricting portion for restricting a flow approaching the width direction center side of the molten glass at both ends in the width direction of the reverse slope portion. The flow restricting portion is inclined so that the thickness increases from the reverse inclined surface portion toward the width direction end portion in the arbitrary horizontal cross section, and the perpendicular to the surface is inclined in the arbitrary vertical cross section. It is characterized by converging at the lower end while maintaining a constant inclination facing downward.

  According to such a configuration, since the flow restricting portion is inclined so that the thickness increases from the reverse inclined surface portion toward the width direction end portion in the arbitrary horizontal cross section, the molten glass is caused by the inclination. Can be guided to the end in the width direction. For this reason, the flow which approaches the width direction center side of a molten glass is controlled reliably, and the shrinkage | contraction of the width direction of a molten glass is suppressed.

  In addition, the flow restricting portion that restricts the flow of the molten glass in this way converges at the lower end while maintaining a constant inclination in which the perpendicular to the surface is inclined obliquely downward in an arbitrary vertical cross section. The direction does not change abruptly along the way. Therefore, it is possible to suppress a local change in thickness (uneven thickness) from occurring in the width direction end portion of the molten glass and to perform stable molding.

  And since a flow control part makes the shape which made compatible the function which controls the shrinkage | contraction of a molten glass in the width direction, and the function which unites and integrates molten glass, it can also contribute to simplification of the structure of a shaping | molding apparatus.

  Said structure WHEREIN: It is preferable that the convergence part of the said flow control part is located on the virtual vertical plane which passes the convergence part of the said reverse slope part.

  If it does in this way, since all the molten glass which flows down the both outer side surface parts of a shaping | molding apparatus is united and integrated on the same virtual vertical plane, it becomes possible to extend | stretch below stably.

  In this case, it is preferable that the converging part of the flow restricting part is located on the same straight line as the converging part of the reverse slope part.

  If it does in this way, the convergence part of a flow control part and the convergence part of a reverse slope part will be located in a line. For this reason, since the positions where the molten glass is fused and integrated are aligned in both the reverse slope portion and the flow restricting portion, the production of the thin glass can be further stabilized.

  Said structure WHEREIN: The surface of the said flow control part may be comprised by the plane, and may be comprised by the curved surface.

  That is, if the surface of the flow restricting portion is flat, the outer surface portion can be easily manufactured. On the other hand, if the surface of the flow restricting portion is a curved surface, it can be smoothly continuous with the surface of the reverse slope portion, and thus there is an advantage that the flow of the molten glass tends to exhibit a uniform distribution.

  Said structure WHEREIN: It is preferable that the said flow control part is integrally molded by the said reverse slope part.

  Since the molding device is formed of a refractory material such as zircon, when the flow restricting portion is formed of a separate member, a high-level joining technique is required when attaching the flow restricting portion to the reverse slope portion. . Therefore, it is preferable that the flow restricting portion is integrally formed with the reverse slope portion. The reason why the integral molding is possible in this way is that the outer surface portion has a simple shape without waste as already described.

  As described above, according to the present invention, the shape of the outer surface portion is simplified, and the width dimension of the product portion of the thin glass to be molded is increased while suppressing the uneven thickness of both ends of the molten glass in the width direction. It is possible to make sure.

It is a schematic perspective view which shows the shaping | molding apparatus of the sheet glass which concerns on 1st Embodiment. It is a side view which expands and shows the flow control part periphery of FIG. It is each horizontal sectional drawing of FIG. 2, (a) is AA sectional drawing, (b) is BB sectional drawing, (c) is CC sectional drawing, (d) is DD sectional drawing. It is. It is each vertical sectional drawing of FIG. 2, (a) is EE sectional drawing, (b) is FF sectional drawing, (c) is GG sectional drawing. It is a side view which expands and shows the flow control part periphery of the shaping | molding apparatus of the sheet glass concerning 2nd Embodiment. It is each horizontal sectional drawing of FIG. 5, (a) is AA sectional drawing, (b) is BB sectional drawing, (c) is CC sectional drawing, (d) is DD sectional drawing. It is. It is each vertical sectional drawing of FIG. 5, (a) is EE sectional drawing, (b) is FF sectional drawing, (c) is GG sectional drawing. It is a side view which expands and shows the flow control part periphery of the shaping | molding apparatus of the sheet glass which concerns on 3rd Embodiment. It is each horizontal sectional drawing of FIG. 8, (a) is AA sectional drawing, (b) is BB sectional drawing, (c) is CC sectional drawing, (d) is DD sectional drawing. It is. It is each vertical sectional drawing of FIG. 8, (a) is EE sectional drawing, (b) is FF sectional drawing, (c) is GG sectional drawing. It is a side view which expands and shows the flow control part periphery of the shaping | molding apparatus of the sheet glass which concerns on 4th Embodiment. It is each horizontal sectional drawing of FIG. 11, (a) is AA sectional drawing, (b) is BB sectional drawing, (c) is CC sectional drawing, (d) is DD sectional drawing. It is. It is each vertical sectional drawing of FIG. 11, (a) is EE sectional drawing, (b) is FF sectional drawing, (c) is GG sectional drawing. It is a figure which shows the analysis model in an Example, (a) is Comparative Example 1, (b) is Comparative Example 2, (c) is Comparative Example 3, (e) is Example 1, (f) is Example. 2 and (g) show analysis models of Example 3 and (h) Example 4, respectively. It is a figure which shows the simulation result of the comparative example 1. It is a figure which shows the simulation result of the comparative example 2. It is a figure which shows the simulation result of the comparative example 3. It is a figure which shows the simulation result of Example 1. FIG. It is a figure which shows the simulation result of Example 2. FIG. It is a figure which shows the simulation result of Example 3. It is a figure which shows the simulation result of Example 4.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is a schematic perspective view showing a thin glass forming apparatus according to a first embodiment of the present invention. In this molding apparatus, the molten glass G overflowing from both sides of the overflow groove 1 is caused to flow down along the outer surface portion 3 via the top flat portion 2, and fused and integrated at a portion called a route where the outer surface portions 3 intersect each other. And a single sheet of glass is continuously formed.

  The outer side surface portion 3 has a vertical surface portion 4 and a reverse slope portion 5. The reverse slope portions 5 are configured by planes inclined at a constant inclination angle, and the reverse slope portions 5 come closer to each other as they move downward, and form a converging portion 5a at the lower end thereof. That is, the convergence part 5a becomes a part called a route. Note that the shape of the vertical surface portion 4 may be changed to an inclined surface or a curved surface, or may be omitted.

  As shown in FIG.1 and FIG.2, the flow control part 6 for controlling the flow which approaches the width direction center part side of the molten glass G is provided in the width direction both ends of the reverse slope part 5. As shown in FIG. . Here, in FIG. 1, 7 is a guide wall portion that defines the flow path width of the molten glass G, and 8 is a supply pipe that continuously supplies the molten glass G into the overflow groove 1. In FIG. 2, the guide wall 7 is omitted. In addition, although the case where the supply pipe 8 is connected to one end side of the overflow groove 1 is illustrated, the method of supplying the molten glass G into the overflow groove 1 is not limited to this, for example, both ends of the overflow groove 1 The molten glass G may be supplied from the side, or the molten glass G may be supplied from above the overflow groove 1.

  As shown in FIG. 3, the flow restricting portion 6 forms an inclined plane whose thickness increases from the reverse inclined surface portion 5 toward the end portion in the width direction in an arbitrary horizontal cross section. That is, at the same height position, the virtual vertical plane passing through the vertical plane portion 4 approaches the end in the width direction. Further, the width-direction dimension W of the flow restricting portion 6 is constant at any position in the vertical direction. In FIG. 3, the guide wall 7 is omitted.

  Furthermore, as shown in FIG. 4, the flow restricting portion 6 converges at the lower end while maintaining a certain inclination in which the perpendicular to the surface (the chain line X in FIG. A convergence portion 6a is formed. The converging part 6a is located on a virtual vertical plane through which the converging part 5a of the reverse slope part 5 passes. In the figure, the overflow groove 1 is omitted.

  Specifically, the converging part 6a of the flow restricting part 6 has the same height (on the same straight line) as the converging part 5a of the reverse slope part 5, and the root angle (tip angle) of the converging part 6a of the flow restricting part 6 ) Θ increases toward the end in the width direction. As shown in FIGS. 1 and 2, the boundary portion L2 between the flow restricting portion 6 and the vertical surface portion 4 is obliquely downward from the boundary portion L1 between the reverse inclined surface portion 5 and the vertical surface portion 4 as it goes toward the width direction end portion. It inclines so that it may move straight.

  The maximum value of the root angle θ of the converging part 6a of the flow restricting part 6 (the root angle at the end on the guide wall part 7 side) is preferably in the range of 30 to 60 °, particularly 35 to 55 °. That is, when the root angle θ of the converging portion 6a of the flow restricting portion 6 is less than 30 °, the difference from the root angle θ (generally 25 to 55 °) of the converging portion 5a of the reverse slope portion 5 becomes too small. Thus, the effect of restricting the flow of the molten glass G toward the center in the width direction in the flow restricting portion 6 may be weakened. On the other hand, when the root angle θ of the converging part 6a of the flow restricting part 6 exceeds 60 °, the vertical dimension of the flow restricting part 6 becomes too short or the inclination angle becomes too large, which is the same as when the route angle is small. There is a possibility that the effect of the flow restricting portion 6 is weakened. Moreover, there exists a possibility that the molten glass G may hang down without following a slope. Therefore, it is preferable that the root angle θ on the center side in the width direction at the end in the width direction of the converging portion 6a of the flow restricting portion 6 is in the above numerical range. The minimum value of the root angle θ of the converging part 6 a of the flow restricting part 6 (the root angle at the end on the reverse slope part 5 side) coincides with the root angle θ of the converging part 5 a of the reverse slope part 5.

  Next, the manufacturing method of the sheet glass by the shaping | molding apparatus comprised as mentioned above is demonstrated.

  As shown in FIG. 1, the molten glass G overflowing on both sides from the overflow groove 1 is continuously supplied to both outer side surface portions 3 via the top plane portion 2. In both outer side surface parts 3, after the molten glass G flows down along the surface of the vertical surface part 4, it flows down along the surface of the reverse slope part 5 provided with the flow restricting part 6. Finally, the molten glass G flowing down on both outer side surface portions 3 is fused and integrated at the converging portions 5a and 6a to continuously form a single sheet glass.

  At this time, as shown in FIG. 3, the flow restricting portion 6 is inclined so that the thickness increases from the reverse inclined portion 5 toward the end portion in the width direction on the arbitrary horizontal plane. The flow at the end in the width direction of the molten glass G flowing down from the vertical surface portion 4 due to the inclination can be captured and guided to the end in the width direction. For this reason, the flow which approaches the width direction center side of the molten glass G is controlled, and it becomes possible to suppress contraction of the width direction of the molten glass G.

  Further, as shown in FIG. 4, the flow restricting portion 6 converges at the lower end while maintaining a certain inclination in which the perpendicular to the surface is inclined obliquely downward in an arbitrary vertical cross section, thereby forming a converging portion 6a. The flow direction of the molten glass G flowing down the flow restricting portion 6 does not change abruptly. Accordingly, it is possible to suppress the local change in thickness at the end portion in the width direction of the molten glass G, and to stably form the thin glass sheet.

  Furthermore, since the flow restricting portion 6 has a shape that simultaneously functions to restrict the shrinkage in the width direction of the molten glass G and to fuse and integrate the molten glass G, the molten glass G flowing down the outer side surface portions 3 is fused. Therefore, there is no need to add a separate member, which can contribute to simplification of the molding apparatus.

  And the thickness of the product part (width direction center part except an ear | edge part) of the thin glass shape | molded in this way will be 10-1000 micrometers, for example. Moreover, the plate | board width of the product part will be 0.5-4 m, for example.

Second Embodiment
As shown in FIGS. 5 to 7, the molding apparatus according to the second embodiment is different from the molding apparatus according to the first embodiment in the shape of the flow restricting portion 6. In addition, since it is common with 1st Embodiment except the structure of the flow control part 6, detailed description is abbreviate | omitted.

  Specifically, in this embodiment, as shown in FIG. 5, the boundary portion L2 between the flow restricting portion 6 and the vertical surface portion 4 is the same height (on the same straight line) as the boundary portion L1 between the reverse inclined surface portion 5 and the vertical surface portion 4. ) And the root angle θ of the converging part 6a of the flow restricting part 6 becomes smaller toward the end in the width direction, as shown in FIG. Thereby, as shown in FIG. 6, the flow restricting portion 6 forms an inclined plane whose thickness increases from the reverse inclined surface portion 5 toward the end portion in the width direction in the arbitrary horizontal cross section. Accordingly, as shown in FIG. 5, the converging part 6a of the flow restricting part 6 shifts downward from the converging part 5a of the reverse slope part 5 as it goes to the end in the width direction. ing.

  The minimum value of the route angle θ of the converging part 6a of the flow restricting part 6 (the root angle at the end on the guide wall part 7 side) is preferably in the range of 20 to 50 °, particularly 25 to 45 °. That is, when the root angle θ of the converging part 6a of the flow restricting part 6 is less than 20 °, the converging part 6a of the flow restricting part 6 protrudes too much below the converging part 5a of the reverse slope part 5, and the structural There is a risk of waste. On the other hand, if the root angle θ of the converging part 6a of the flow restricting part 6 exceeds 50 °, the difference from the root angle θ of the converging part 5a of the reverse slope part 5 becomes too small, and the molten glass G in the flow restricting part 6 There is a possibility that the effect of restricting the flow to the center portion side in the width direction is weakened. Therefore, the root angle θ at the end in the width direction of the converging part 6a of the flow restricting part 6 is preferably in the above numerical range. The maximum value of the root angle θ of the converging part 6 a of the flow restricting part 6 (the root angle at the end on the reverse slope part 5 side) coincides with the root angle θ of the converging part 5 a of the reverse slope part 5.

<Third Embodiment>
As shown in FIGS. 8 to 10, the molding apparatus according to the third embodiment is different from the molding apparatus according to the first and second embodiments in the shape of the flow restricting portion 6. In addition, since it is common with 1st Embodiment except the structure of the flow control part 6, detailed description is abbreviate | omitted.

  Specifically, in this embodiment, as shown in FIG. 10, the root angle θ of the converging part 6a of the flow restricting part 6 is the same as the root angle θ of the converging part 5a of the reverse slope part 5, and FIG. As shown in FIG. 4, the converging part 6a of the flow restricting part 6 is shifted diagonally downward from the converging part 5a of the reverse slope part 5 toward the end in the width direction. Accordingly, as shown in FIG. 9, the flow restricting portion 6 forms an inclined plane whose thickness increases from the reverse inclined surface portion 5 toward the end portion in the width direction in the arbitrary horizontal cross section. With such a configuration, as shown in FIG. 8, the boundary between the flow restricting portion 6 and the vertical surface portion 4 moves toward the end in the width direction, and the boundary between the reverse inclined surface portion 5 and the vertical surface portion 4. It moves to the lower part from the part.

<Fourth embodiment>
As shown in FIGS. 11 to 13, the molding apparatus according to the fourth embodiment is different from the molding apparatus according to the first to third embodiments in the shape of the flow restricting portion 6. Since the configuration other than the flow restricting unit 6 is the same as that of the first embodiment, detailed description thereof is omitted.

  Specifically, in this embodiment, as shown in FIG. 13, the root angle θ of the converging part 6a of the flow restricting part 6 is the same as the root angle θ of the converging part 5a of the reverse slope part 5, and FIG. As shown in FIG. 4, the converging part 6a of the flow restricting part 6 moves downward from the converging part 5a of the reverse slope part 5 as it goes to the end in the width direction. Here, in the third embodiment, the shape change of the converging portion 5a of the reverse slope portion 5 is linear, whereas in this embodiment, the shape change of the converging portion 5a of the reverse slope portion 5 is a parabola. It has become a shape. As a result, as shown in FIG. 12, the flow restricting portion 6 forms a curved surface whose thickness increases from the reverse slope portion 5 toward the width direction end portion in the arbitrary horizontal cross section. With such a configuration, as shown in FIG. 11, the boundary between the flow restricting portion 6 and the vertical surface portion 4 moves toward the end in the width direction, and the boundary between the reverse inclined surface portion 5 and the vertical surface portion 4. It moves to the lower part from the part.

  The preferable range of the root angle θ at the end in the width direction of the converging part 6a of the flow restricting part 6, that is, the minimum value of the root angle θ is the same as that of the third embodiment.

  In the analytical model which simplified the range of 300 mm from the guide wall portion of the forming apparatus as shown in FIGS. 14A to 14H, the behavior of the molten glass flowing down the outer surface portion was analyzed, and the flow and thickness of the molten glass. The distribution was determined. In the simulation, plate drawing below the forming apparatus is not taken into consideration.

The outline of the analysis model is as follows.
(1) Comparative Example 1: As shown in FIG. 14A, a standard molding apparatus having a constant root angle of 40 °.
(2) Comparative Example 2: As shown in FIG. 14 (b), a standard molding apparatus having a constant root angle of 30 °.
(3) Comparative Example 3: As shown in FIG. 14 (c), a molding apparatus in which the root tip is the same height, the root angle at the center is 40 °, and the root angle at the end in the width direction is 30 °. .
(4) Example 1: As shown in FIG. 14 (d), a molding apparatus in which the root tip is the same height, the root angle at the center is 40 °, and the root angle at the end in the width direction is 50 °. (Corresponding to the first embodiment).
(5) Example 2: As shown in FIG. 14 (e), the end of the root is located below the center in the width direction and the shape change is linear, and the root angle at the center is A forming apparatus (corresponding to the second embodiment) in which the root angle at the end in the width direction is 40 ° and 30 °.
(6) Example 3: As shown in FIG. 14 (f), the root end is located below the center part in the width direction and the shape change is linear, and the center part and the width direction end. A molding apparatus in which the root angle of the part is constant at 40 ° (corresponding to the third embodiment).
(7) Example 4: As shown in FIG. 14 (g), the root tip is located at the lower end of the width direction with respect to the central portion, and the shape change is a parabolic shape. A molding apparatus having a constant root angle of 40 ° (corresponding to the fourth embodiment).

  Next, simulation results using the above analysis model are shown in FIGS. In the drawing, the arrows indicate the flow of the molten glass, and the shades of the color indicate the thickness of the molten glass, and the thickness increases as it becomes darker.

  As shown in FIGS. 15 to 17, in Comparative Examples 1 to 3, a flow in which the molten glass approaches the center side in the width direction (opposite side to the guide wall portion) can be confirmed near the tip of the route. Shrinkage in the width direction of the molten glass is observed. In other words, Comparative Example 2 having a smaller root angle than Comparative Example 1 resulted in a smaller shrinkage of the molten glass, but the difference was slight.

  On the other hand, as shown in FIGS. 18-21, in Examples 1-4, the flow in which the molten glass which flows down the part corresponding to a flow control part approaches the center side of the width direction is suppressed. In the simulation, it is recognized that the shrinkage in the width direction of the molten glass and the local thickness fluctuation (uneven thickness) at both ends in the width direction are improved. In particular, in Example 4, since the reverse slope portion and the flow regulating portion are smoothly continuous, it can be confirmed that the flow distribution of the molten glass is further improved and the uneven thickness can be significantly reduced.

DESCRIPTION OF SYMBOLS 1 Overflow groove | channel 2 Top plane part 3 Outer side surface part 4 Vertical surface part 5 Reverse slope part 5a Convergence part (route) of a reverse slope part
6 Flow restriction part 6a Convergence part (route) of flow restriction part
7 Guide wall G Molten glass

Claims (6)

The molten glass is caused to flow down along both outer surface portions, and is integrally formed at a converging portion formed at the lower end of the reverse slope portion of the both outer surface portions to continuously form a single sheet glass, and the reverse A thin glass forming apparatus having a flow restricting portion for restricting the flow approaching the width direction center side of the molten glass at both ends in the width direction of the slope portion,
The flow restricting portion is inclined so that the thickness increases from the reverse inclined surface portion toward the width direction end portion in the arbitrary horizontal cross section, and the perpendicular to the surface in the arbitrary vertical cross section is obliquely below. An apparatus for forming thin glass, characterized in that it converges at the lower end while maintaining a constant inclination.   The thin glass forming apparatus according to claim 1, wherein the converging part of the flow restricting part is located on a virtual vertical plane passing through the converging part of the reverse slope part.   The thin glass forming apparatus according to claim 1 or 2, wherein a surface of the flow restricting portion is a flat surface.   The thin glass forming apparatus according to claim 1 or 2, wherein a surface of the flow restricting portion is formed of a curved surface.   The thin glass forming apparatus according to any one of claims 1 to 4, wherein the flow restricting portion is integrally formed with the reverse slope portion.   A method for forming a thin glass, comprising using the thin glass forming apparatus according to any one of claims 1 to 5 to form a thin glass.