TWI627140B - Method and apparatus for minimizing devitrification on edge directors with induction heating - Google Patents

Abstract

The fusion drawing method includes the steps of flowing molten glass over the edge guide, the edge guide intersecting at least one of a pair of downwardly inclined forming surface portions, and heating the edge guide by induction The minimum temperature at which the edge guide contacts at least a portion of the surface of the molten glass is maintained above a predetermined amount.

Description

Method and apparatus for minimizing devitrification on edge guides by induction heating [Cross-reference to related applications]

This application claims priority to U.S. Provisional Application No. 61/740,541, filed on Dec. 21, 2012, and U.S. Provisional Application No. 61/880,332, filed on Sep. 20, 2013. The content of these applications is hereby incorporated by reference in its entirety in its entirety herein in its entirety herein in its entirety herein

This description is generally directed to the manufacture of glass sheets and, more particularly, to apparatus and methods for making glass sheets with edge guides.

Glass manufacturing systems are commonly used to form a variety of glass products, such as LCD glass sheets. It is known to make glass sheets by flowing molten glass down the shaped wedge. Edge guides are often provided at the opposite ends of the shaped wedge to help achieve the desired glass sheet width and edge bead characteristics.

During manufacture, the glass passing through the edge guides can be cooled and lost Through, formed on the edge guide. This formation can result in shape-related defects and other defects in the glass, as well as the need to frequently change the edge guides. Therefore, there is a need for a method of minimizing the formation of devitrified glass on edge guides.

Embodiments described herein relate to apparatus and methods for making glass sheets using edge guides that are heated by induction.

According to one embodiment, a method of making a fused glass sheet includes the steps of flowing molten glass over a portion of the forming wedge that slopes downwardly toward the contoured surface portion, the downwardly sloping shaped surface portions converge in a downstream direction Form the roots. The method also includes the step of flowing the molten glass over an edge guide that intersects at least one of the pair of downwardly inclined forming surface portions. Additionally, the method includes the step of maintaining a minimum temperature of at least a portion of the surface of the edge guide contacting the molten glass by the induction heating edge guide above a predetermined amount. The method further includes the step of drawing the molten glass from the root of the shaped wedge to form a glass sheet.

In another embodiment, an apparatus for pulling down a glass sheet includes a forming wedge having a pair of downwardly inclined forming surface portions, the downwardly inclined forming surface portions being shaped wedges Converging at the bottom to form a root and defining a draw line for the molten glass along the draw line. The apparatus also includes an edge guide that contacts at least one of the pair of downwardly angled shaped surface portions. The edge guide includes an induction coil positioned behind the surface of the edge guide for maintaining a minimum temperature of the edge guide contacting at least a portion of the surface of the molten glass by inductively heating the edge guide At a predetermined amount.

It should be understood that the foregoing general description and the following detailed description describe both Various embodiments are intended to provide an overview or framework for understanding the nature and characteristics of the claimed subject matter. A further understanding of the various embodiments is provided by the accompanying drawings, and is incorporated in the claims The drawings illustrate the various embodiments described herein and, together with the description

10‧‧‧ Equipment

12‧‧‧Stainless glass

13‧‧‧ edge

14‧‧‧melting tank

16‧‧‧ batches

18‧‧‧Storage warehouse

20‧‧‧Batch conveyor

22‧‧‧Motor

24‧‧‧ Controller

28‧‧‧Solid glass level probe

30‧‧‧ standpipe

36‧‧‧First connecting pipe

38‧‧‧Clarification tank

40‧‧‧Second connection tube

42‧‧‧ Mixing tank

44‧‧‧ Third connecting pipe

46‧‧‧ conveyor

48‧‧‧Sewage pipe

50‧‧‧ entrance

60‧‧‧ forming trough

62‧‧‧Formed wedge

62'‧‧‧Formed wedge

End of 64a‧‧

End of 64b‧‧‧

66a‧‧‧Looking down the forming surface section

66b‧‧‧Looking down the forming surface section

66a'‧‧‧Looking down the forming surface section

66b'‧‧‧Looking down the forming surface section

68‧‧‧Downstream direction

70‧‧‧ Root

72‧‧‧Draw plane

80a‧‧‧Edge guides

80b‧‧‧Edge guide

80'‧‧‧Edge guides

82‧‧‧ first surface

84‧‧‧keeping block

86‧‧‧ upper

86'‧‧‧ upper

88‧‧‧ lower

88'‧‧‧ lower

90‧‧‧Induction coil

90A‧‧‧Area

90B‧‧‧Area

90C‧‧‧Area

90'‧‧‧Induction coil

92‧‧‧ trough type conductive plate

94‧‧‧Cylindrical coolant conduit

96‧‧‧ Rectangular Coolant Catheter

110a‧‧‧First heat-shielding equipment

110b‧‧‧second heat shielding equipment

120a‧‧‧First heat shield

120b‧‧‧second heat shield

130a‧‧‧First edge roller assembly

130b‧‧‧Second edge roller assembly

132‧‧‧First pair of edge rollers

132a‧‧‧First edge roller

132b‧‧‧second edge roller

134a‧‧‧first axis

134b‧‧‧second axis

136‧‧‧ Sealing plate

180‧‧‧ Backplane

182‧‧‧ inner surface

184‧‧‧ outer surface

200‧‧‧thermal beads

210a‧‧‧First heat-shielding equipment

222‧‧‧ hot plate

End of 224‧‧‧

226‧‧‧ slot

400‧‧‧cooler

402‧‧‧Coolant input line

452‧‧‧ Coolant output line

500‧‧‧AC power supply

502‧‧‧ Circuitry

504‧‧‧ Circuit

506‧‧‧ Circuit

508‧‧‧ Circuit

550‧‧‧heating station

600‧‧‧ controller

602‧‧‧Control loop

1000‧‧‧Induction heating system

1WA‧‧‧First wing shaft

2WA‧‧‧second wing shaft

CA‧‧‧ central axis

H‧‧‧ level

P‧‧‧ plane

V‧‧‧Vertical

X‧‧‧ points

1 is a schematic view of an apparatus for manufacturing glass; FIG. 2 is a cross-sectional perspective view of the apparatus along the line 2-2 of FIG. 1 showing a first example of the heat shielding apparatus; FIG. 2A is an apparatus a perspective view showing another example of the heat shield apparatus; Fig. 3 is a perspective view of the induction heating edge guide shown by a schematic diagram of the induction heating system; and Fig. 4 is a perspective view of the induction coil arrangement; 5A and 5B are perspective views, respectively, of an alternative embodiment of the induction heating system assembly; FIGS. 6A and 6B are cross-sectional views of the edge guide having the backing plate and the induction coil positioned behind the backing plate, respectively. And a perspective view; and Figure 7 is a perspective view of the edge guide having the backing plate, wherein the area between the inner surface of the backing plate and the edge guide contacting the inner surface of the molten glass is filled with thermally conductive beads.

Reference will now be made in detail to the glass used to make glass sheets and merging glass sheets. Various embodiments of the manufacturing process. Wherever possible, the same reference numerals reference to the The glass sheet material can generally be formed by melting a glass batch to form a molten glass and subsequently forming the molten glass into a glass sheet. Exemplary processes include a float glass process, a slot draw process, and a fused pull down process.

FIG. 1 illustrates a schematic diagram of an apparatus 10 for making glass, such as glass sheet 12 . Device 10 may include a melting tank 14, the melting tank 14 is configured to receive from the storage bin 18 of the batch 16. The batch 16 can be introduced into the melting tank 14 by a batch delivery device 20 powered by a motor 22 . An optional controller 24 starter motor 22 can be provided and the molten glass level probe 28 can be used to measure the glass melt level in the riser 30 and communicate measurement information to the controller 24 .

Device 10 also comprises a clarification tank 38 (such as a clear tube), the settling tank 38 is located downstream of the melting tank 14 by a first connecting pipe 36 and coupled to the melting tank 14. A mixing tank 42 (such as an agitation chamber) may also be located downstream of the clarification tank 38 , and a trough 46 , such as a bowl, may be located downstream of the mixing tank 42 . As shown, the second connecting tube 40 can couple the clarification tank 38 to the mixing tank 42 , and the third connecting tube 44 can couple the mixing tank 42 to the conveying tank 46 . As further shown, the downcomer 48 can be positioned to transport the glass melt from the trough 46 to the inlet 50 of the forming trough 60 . As shown, the melt tank 14 , the clarification tank 38 , the mixing tank 42 , the transfer tank 46, and the forming tank 60 are examples of glass melt stations that can be positioned in series along the apparatus 10 .

The melting tank 14 is typically made of a refractory material such as a refractory (e.g., ceramic) brick. Apparatus 10 may further comprise components, typically made of platinum or a platinum-containing metal, such as platinum rhodium, platinum rhodium, and combinations of the foregoing, but such metals may also comprise such refractory metals, such as , molybdenum, palladium, rhodium, iridium, titanium, tungsten, lanthanum, cerium, zirconium and alloys of the above and/or zirconium dioxide. The platinum-containing component may include one or more of the first connecting pipe 36 , the clarifying tank 38 , the second connecting pipe 40 , the riser 30 , the mixing tank 42 , the third connecting pipe 44 , the conveying groove 46 , the down pipe 48, and the inlet 50 . By. The forming groove 60 can also be made of a refractory material and designed to form a glass sheet 12 .

Figure 2 is a cross-sectional perspective view of the apparatus 10 along line 2-2 of Figure 1. As shown, forming wedge shaped groove 60 includes a 62, the shaped wedge 62 includes a pair of downwardly inclined forming surface portions 66a, 66b, the pair of downwardly inclined forming surface portions 66a, 66b may be formed in wedge The opposite ends 64a , 64b of the object 62 extend between. The downwardly inclined forming surface portions 66a , 66b converge in a downstream direction 68 to form a root 70 . The draw plane 72 extends through the root 70 where the glass sheet 12 can be drawn along the draw plane 72 in the downstream direction 68 . As shown, the draw plane 72 can bisect the root 70 , although the draw plane 72 can extend in other orientations relative to the root 70 . Aspects of the present disclosure can be used with a variety of forming slots. For example, the aspects of the present disclosure can be used with an apparatus for reducing the radiant heat loss from a self-forming body, which is disclosed in U.S. Provisional Patent Application Serial No. 61/180,216, filed on May 21, 2009. The full text of the case is incorporated herein by reference.

The forming groove 60 can include an edge guide that intersects at least one of the pair of downwardly inclined forming surface portions 66a , 66b . In a further example, the edge guides can intersect both of the downwardly inclined forming surface portions 66a , 66b . Alternatively or additionally, the edge guides can be positioned at each of the opposite ends of the shaped wedge 62 . For example, as shown in FIG. 1, edge guides 80a , 80b can be positioned at each of the opposite ends 64a , 64b of the shaped wedge 62 , with each edge guide 80a , 80b configured Intersecting with the downwardly inclined forming surface portions 66a , 66b . As further shown, each of the edge guides 80a , 80b is substantially identical to one another, although in further examples, the edge guides can have different characteristics. Various shaped wedges and edge guide configurations can be used in accordance with aspects of the present disclosure. For example, the disclosure of the present disclosure can be applied to US Provisional Patent Application No. 3,451,798, U.S. Patent No. 3,537,834, U.S. Patent No. 7,409,839, and/or U.S. Patent Application Serial No. The shaped wedge and edge guide configurations disclosed in the '155, 669 are incorporated herein by reference.

Figures 2 and 2A illustrate only one exemplary edge guide that can be used with the aspects of the present disclosure. In understood that the second edge guide member 80b may be in some instances where the first edge guide member 80a similar or identical, will be discussed first edge guide member 80a. Providing the same edge guide can facilitate providing a uniform glass sheet, although the edge guides can have different features to provide various glass sheet characteristics and/or accommodate various shaped slot configurations.

2 and 2A illustrate the first side of the first edge guide 80a positioned relative to the first downwardly sloped shaped surface portion 66a of the shaped wedge 62 . Although not shown, the first edge guide 80a further includes a second side that is positioned relative to the second angled contoured surface portion 66b of the shaped wedge 62 . The second side of the first edge guide 80a is a mirror image of the first side with respect to the draw plane 72 that bisects the root 70 . As shown, the first side 82 includes a first surface, the first surface 82 of the forming wedge forming a first downwardly sloping surface 62 of the intersecting portion 66a. Although not shown, the second side of the first edge guide 80a also includes a substantially identical surface that intersects the second angled contoured surface portion 66b of the shaped wedge 62 .

Each wedge shaped end 62 of the opposing 64a, 64b may have a holding block 84, the holding block 84 is designed to help locate the corresponding lateral edge of the first guide member 80a and the second edge guide member 80b. Optionally, as shown, the first edge guide 80a can include an upper portion 86 and a lower portion 88 . In some examples, the lower portion 88 can incorporate the first edge guide 80a on the first opposite end 64a and the second edge guide 80b on the second opposite end 64b . Joining the edge guides 80a , 80b together may facilitate simplification of the assembly of the edge guides 80a , 80b to the forming wedge 62 . In a further example, the upper portion 86 of the edge guides 80a , 80b can be provided separately. For example, as shown, the first edge guide 80a can be separate from the second edge guide 80b and independently assembled to the pair of downwardly inclined forming surface portions 66a , 66b of the forming wedge 62 . Each. For some configurations, providing unbonded upper portion 86 may simplify the manufacture of edge guides 80a , 80b . Each of the edge guides 80a , 80b can have various orientations and geometries by providing different surfaces relative to the shaped wedge 62 .

The apparatus 10 for making glass may also include at least one edge roller device including a pair of edge rollers configured to draw away from the root 70 of the forming wedge 62 at the glass ribbon. The corresponding edges of the belt are engaged. The pair of edge rollers promote the proper finishing of the edges of the glass sheets. The edge roller finish provides the desired edge characteristics and proper fusion of the edge portions of the molten glass that are pulled away from the opposing surfaces of the edge guides associated with the pair of downwardly sloped shaped surface portions 66a , 66b . In one example, the edge rollers can be located at various locations within the viscous area of the glass drawn from the root 70 . For example, from the edge of the drum may be located directly below the root 70 at any location to the position of approximately 15 inches below the root 70, in a further example, although other locations may be considered. In yet another example, the edge roller can be located at a location within about 8 inches to about 10 inches below the root portion 70 .

As shown in FIG. 1, the first edge roller assembly 130a is associated with the first edge guide 80a and the second edge roller assembly 130b is associated with the second edge guide 80b . As further shown, each edge roller assembly 130a , 130b is substantially identical to one another, although in further examples, the pair of edge rollers can have different characteristics.

Figure 2 illustrates an exemplary edge roller assembly that can be used with the aspects of the present disclosure. In the drum cartridge understood that the second edge 130b may be the first edge of the drum cartridge, in some instances where similar or identical 130a, the drum assembly will be discussed first edge 130a. As shown in FIG. 2, the first edge of the roller assembly 130a includes a first pair of edge rollers 132, the first pair of edge rollers 132 includes a first edge and a second edge roller cylinder 132a 132b. The edge rollers 132a , 132b are configured to simultaneously engage the first side and the second side of the glass sheet 12 . The first edge 130a of the drum assembly further comprises a first shaft 134a and second shafts 134b, 134a of the first shaft attached to the first edge roller 132a, the second shaft 134b is attached to the second edge of the drum 132b. The first shaft 134a and the second shaft 134b extend through the seal plate 136 and are configured to be rotatably driven by a motor (not shown). Sealing plate 136 is configured to provide closure of the opening to create an area that houses motor 138 . The sealing plate may comprise refractory material, steel or other insulation that protects sensitive components of the motor and/or other mechanisms located within the containment area.

The forming slot 60 also has a heat shield device that includes a thermal shield associated with at least one of the edge guides 80a , 80b . The thermal shield is configured to reduce heat loss from the respective edge guides 80a , 80b to the non-target area, and in particular, heat loss to the cooled edge drum. The non-target areas may include areas adjacent to the glass making equipment and/or other locations capable of receiving heat transfer from the edge guides. As shown in FIG. 1, the first thermal shield device 110a includes a first thermal shield 120a associated with the first edge guide 80a . Likewise, the second thermal shield device 110b includes a second thermal shield 120b associated with the second edge guide. As further shown, each of the heat shield devices 110a , 110b are substantially identical to one another, although in further examples, the heat shield devices can have different characteristics. Providing the same heat shield device can facilitate providing similar thermal shielding of the edge guides, although the heat shield device can have different features to accommodate various shaped slot configurations.

Figure 2 illustrates only one exemplary thermal shielding device that can be used with the aspects of the present disclosure. In the second thermal shield device 110b appreciated that in some instances may be similar or identical to the case of the first thermal shield apparatus 110a, it will be discussed first thermal shield apparatus 110a.

The first heat shield can be positioned below a portion or the entire first edge guide and extends generally in the lengthwise direction relative to the long dimension of the shaped wedge and in close proximity to the edge roller axis. As shown in FIG. 2, the first thermal shield 120a can be positioned to be positioned just below a portion of the first edge guide 80a . Providing the first thermal shield 120a at a location just below a portion of the first edge guide 80a can provide sufficient heat loss to the non-target area while avoiding molten glass drawn from the root 70 of the self-forming wedge 62 . Possible interference.

The first heat shield can also extend completely under the first edge guide. For example, Figure 2A illustrates another example of a first thermal shielding device 210a associated with the first edge guide 80a . As shown, the first thermal shield device 210a includes a thermal plate 222 having an end 224 that terminates inside a respective edge 13 of the glass sheet 12 . In one example, the hot plate 222 extends only with respect to one side of the glass sheet 12 , allowing the thermal shield to extend under the entire first edge guide. Alternatively, as shown, the thermal plate 222 can include slots 226 to provide access to the edges 13 and corresponding edge portions of the glass sheet 12 . As such, the ends 224 of the hot plate 222 extend relative to both sides of the glass sheet 12 while allowing thermal shielding to extend beneath the entire first edge guide 80a . Positioning the heat shield to extend under the entire first edge guide 80a minimizes heat loss from the first edge guide 80a to the non-target area.

Figure 3 illustrates a second example with the forming wedge 62 'of the edge guide member 80' of the molded wedge 62 'has a pair of downwardly inclined forming surface portions 66a', 66b '. The edge guide 80' includes an upper portion 86' and a lower portion 88' , and the edge guide 80' and the shaped wedge 62' are illustrated in a lower left perspective view in FIG. The induction coil 90 is positioned behind the surface of the edge guide 80' . Inductive coil 90 includes a plurality of turns that are sufficient to cause a desired amount of inductive heating of edge guide 80' after application of sufficient alternating current to induction coil 90 .

FIG 3 also illustrates a schematic view of an induction heating system 1000, the induction heating system 1000 can be used to facilitate the induction heating edge guide member 80 '. The induction heating system 1000 includes an AC power supply 500 , a heating station 550 , a cooler 400 for supplying a coolant, and a controller 600 . Induction heating system 1000 also includes a cooling fluid input line 402 and output line 452 a coolant, the coolant input line 402 for guiding the cooling fluid from the cooler 400 to the AC power supply 500, the heating station 550 and the induction coil 90, The coolant output line 452 is used to direct the flow of coolant from the induction coil 90 back to the cooler 400 . In addition, the induction heating system 1000 includes an AC power supply 500 , a circuit 502 between the heating station 550 and the induction coil 90 , a circuit 504 , a circuit 506, and a circuit 508 . Induction heating system 1000 further includes a control circuit 602, the control circuit 602 for enabling the controller 600 to provide management control of the edge guide member 80 'of the induction heating, comprising a contact edge surface of the guide member at least a portion of the molten glass The minimum temperature.

In a preferred embodiment, the cooling liquid is water.

In operation, alternating current is supplied from the AC power supply 500 to the heating station 550 and the induction coil 90 via the circuit 502 , the circuit 504 , the circuit 506, and the circuit 508 , while the coolant passes through the coolant input line 402 and the coolant output line 452. The self-cooler 400 is guided through the AC power supply 500 , the heating station 550, and the induction coil 90 . The amount and frequency of the alternating current, as well as the flow rate of the coolant, can be simultaneously controlled via controller 600 and control loop 602 to provide management control of the inductive heating of edge guide 80' . The control may, for example, include or be forwarded to a computer processing unit, and the unit may process, for example, feedback or feedforward control in accordance with process control methods known to those skilled in the art.

Moreover, the control may allow the edge guide to be heated by induction such that the minimum temperature of at least a portion of the surface of the edge guide that contacts the molten glass is maintained in a steady state as close to a constant temperature as possible. For example, the minimum temperature of the edge guide contacting at least a portion of the surface of the molten glass The predetermined duration may be maintained in a steady state at a predetermined temperature that does not change by more than ±10 ° C, such as not exceeding ± 5 ° C, and further such as, for example, no more than ± 2 ° C, and still further such as, for example, no more than ±1 °C. The predetermined duration (not limited) may be at least 1 hour, such as at least 10 hours, and further such as at least 25 hours, including from 1 hour to 10 years, such as from 10 hours to 5 years, and further such as from 20 Hours to 1 year.

In a preferred embodiment, the minimum temperature (not the limit) should be at least The liquidus temperature above the molten glass flowing over the surface of the edge guide is maintained to minimize the formation of the devitrified glass on the edge guide. For example, in certain preferred embodiments, the molten glass is borosilicate glass and should be maintained at a minimum temperature above the liquidus temperature of the borosilicate glass. In certain preferred embodiments, the surface of the edge guide that contacts the molten glass is maintained above 1150 ° C, such as above 1200 ° C, and further such as above 1250 ° C, including from 1000 ° C to 1700 ° C, including 1100 ° C to 1600 ° C, and further includes from 1150 ° C to 1400 ° C.

The edge guide 80' , the induction coil 90, and the induction heating system 1000 can also be configured to enable rapid change of at least a portion of the surface of the edge guide that contacts the molten glass, for example, in response to a predetermined factor that would require a change in the temperature. temperature. For example, if the composition of the glass flowing over the edge guide changes such that the liquidus temperature of the composition will also change, the minimum temperature of at least a portion of the surface of the edge guide will change accordingly. In this regard, the controller 600 can be integrated into a control algorithm that not only controls the induction heating system, but also controls the entire apparatus shown in FIG. 1, wherein the temperature of the surface of the edge guide will respond to Or any number of processing parameters or measurements or desired glass characteristics (including but not limited to glass composition, glass temperature, glass devitrification temperature, glass viscosity, and glass flow rate) are expected to vary.

For example, embodiments disclosed herein include their embodiments, Wherein the minimum temperature of the edge guide contacting at least a portion of the surface of the molten glass may be at a rate of at least 1000 ° C (including temperatures from 1000 ° C to 1400 ° C) at a rate of at least 10 ° C per minute (including at least per minute) 20 ° C, such as from 10 ° C per minute to 30 ° C per minute) changes.

The induction coil 90 can be configured such that a minimum temperature of at least a portion of the edge guide contacting the surface of the molten glass can be disposed on the surface of the edge guide 80' by inducing that the direct heating edge guide 80' is maintained above a predetermined amount. Behind. In this regard, the induction coil 90 can be configured to have a variable coil density per unit area of the edge guide 80' and or at a variable distance away from the edge guide 80' such that the edge guide The temperature of the surface contacting the molten glass changes from a maximum temperature at a point or region on the surface of the edge guide to a lower temperature at other points or regions on the surface of the edge guide. In this way, a temperature profile may exist on the surface of the edge guide, wherein the difference between the maximum temperature and the minimum temperature on the surface of the edge guide changes by a predetermined amount.

For example, in the embodiment illustrated in FIG. 3, the induction coil 90 is configured to have a greater amount of density than the coil embedded behind the surface of the upper portion 86' of the edge guide, embedded in the lower portion 88 of the edge guide. ' The amount of coil density behind the surface. In this embodiment, when the molten glass flows over the edge guide 80' , the local maximum temperature of the surface of the edge guide will be expected to be at a point or region on the lower portion 88' of the edge guide 80' .

Other embodiments (not shown) may include embodiments in which the induction coil 90 has a coil density per unit area that is more uniform behind the entire surface of the edge guide 80' . Additional embodiments (not shown) may include a surface in which the induction coil 90 is configured to have a greater amount of coil density than the surface embedded behind the surface of the lower portion 88' of the edge guide, embedded on the surface of the upper portion 86' of the edge guide These examples of the amount of coil density that follows.

For example, embodiments disclosed herein include a temperature profile therein Existing on the surface of the edge guide such that the maximum temperature on the surface of the edge guide contacting the molten glass is greater than a minimum temperature on the surface of the edge guide by at least 25 ° C, such as at least greater than 50 ° C, and further such as Examples of at least greater than 100 ° C. For example, embodiments disclosed herein can include embodiments in which the difference between the maximum temperature and the minimum temperature on the surface of the edge guide is from 25 ° C to 250 ° C, such as from 50 ° C to 150 ° C. example. Depending on the location of the temperature on the surface of the edge guide, the temperature profiles may be approximately linear or non-linear.

Embodiments disclosed herein include wherein the sensing is provided to the edge via induction The embodiment of the heat of the guide changes according to the predetermined profile as a function of the position of the edge guide surface. For example, in an exemplary embodiment, the heat provided to the edge guide via induction may increase or decrease with the vertical position on the edge guide surface. In a preferred embodiment, the heat provided to the edge guide via induction increases as the vertical position on the edge guide surface decreases.

For example, the induction coil can be configured to maximize heat transfer efficiency to the surface of the edge guide and/or provide a more uniform degree of heat flux to the various surfaces of the edge guide. For example, as shown in FIG. 4, the induction coil can be configured such that the coil extends through at least three regions, the first region being the region 90A closest to the center of the edge guide (hereinafter referred to as "the center" The area ") and the other two areas 90B , 90C (hereinafter referred to as "first wing area" and "second wing area" respectively) on either side of the center area. In certain exemplary embodiments, such as shown in FIG. 4, the portion of the coil that extends in the central region is configured to protrude forward relative to the first and second wing regions. In certain exemplary embodiments, such as shown in FIG. 4, a portion of the coil in the central region is configured such that the coil extends perpendicular to a portion of the coil in the first and second wing regions. To a greater extent, the vertical V -shape extends, and portions of the coil in the first wing region and the second wing region are configured such that the portions extend to a greater extent than the horizontal extent of the portion of the coil in the central region Upper horizontal H -shaped extension. In certain exemplary embodiments, such as shown in FIG. 4, the portion of the coil in the central region has at least three substantially parallel loops that circulate around the central axis CA and the coil is in the first wing shape the area portion and a coil portion of a second wing region each having at least two substantially parallel circuit, these circuits are surrounded by a first wing and a second wing axis shaft 1WA 2WA cycle, wherein the first wing The axis of the axis and the second wing axis intersect at a point X on a plane P perpendicular to the central axis.

Embodiments disclosed herein include embodiments in which the edge guide 80' comprises at least one material selected from the group consisting of platinum, rhodium, palladium, rhodium, and the like. An alloy of at least one of the materials. In a particularly preferred embodiment, the edge guide 80' comprises platinum. The edge guide 80' may also comprise an alloy of platinum and tin.

The thickness (but not limitation) of the edge guide 80' is preferably less than 10 mm, such as from 0.5 mm to 5 mm, including about 1 mm. The thickness can be relatively constant or can be variable.

In certain exemplary embodiments where it is desired to directly heat the edge guide by induction, the induction coil 90 should preferably be embedded behind the surface of the edge guide 80' as close as possible to the surface of the edge guide. The maximum temperature of the edge guide is required at the surface. For example, the 'portion of the inner surface of the guide member 80 from the edge of' In the preferred embodiment, the induction coil 90 may be configured so that the coil closest to the edge surface of the guide member 80 within less than 10 mm, such as less than 5 Millimeters, and further such as less than 2 mm.

Embodiments disclosed herein include embodiments in which the induction coil 90 comprises at least one material selected from the group consisting of copper, nickel, platinum, gold, silver, and the like. An alloy of at least one. In a particularly preferred embodiment, the induction coil 90 comprises copper.

In certain exemplary embodiments, the induction coil 90 can be coated, insulated, sheathed, or embedded with at least one material that provides, for example, thermal, mechanical, and/or corrosion protection. For example, in certain exemplary embodiments, the induction coil can be packaged in a fabric material comprising at least one material selected from the group consisting of alumina and ceria.

By way of example, embodiments herein include embodiments in which the induction coil 90 comprises a copper tube having a diameter from 2 mm to 15 mm, such as from 4 mm to 10 mm, and further such as 4 mm to 7 mm. In such embodiments, the copper tube can have, for example, a radial thickness from 0.5 mm to 1 mm.

When the edge guide 80' comprises platinum, the induction coil 90 should preferably be configured to enable inductive heating of the platinum such that at least a portion of the surface of the edge guide has a minimum temperature of at least 1000 °C, such as at least 1100 °C. And further such as at least 1150 ° C, and further such as at least 1200 ° C, and still further such as at least 1250 ° C, and even further one step such as at least 1300 ° C, including from 1000 ° C to 1700 ° C, such as from 1100 ° C to 1600 ° C And further such as from 1200 ° C to 1500 ° C. Proximate the induction heating coil 90 depending on the induction of the line number per unit area of the turns of the induction coil 90 and the edge guide member 80 'and the inner surface from the AC power supply 500 supplies alternating current to the amount and frequency of the induction coil 90 set.

Although not limited, the preferred embodiment includes a power supply therein Providing at least 5 kW of power (such as at least 7.5 kW, and further such as at least 10 kW, and further such as at least 15 kW, including power from 2 kW to 20 kW, such as from 5 kW to 15 kW) and at least Embodiments of alternating current of 50 kHz (such as at least 100 kHz, and further such as at least 150 kHz, such as from 50 kHz to 250 kHz).

The coolant can prevent the rate of undesirable softening, deformation or melting of the induction coil 90 and the temperature supply while maintaining the AC power supply 500 sufficiently cooled. For example, cooling water can be supplied from the cooler 400 to the induction coil 90 at a temperature of from about 0 °C to about 50 °C, including about 25 °C. The coolant flow rate can range, for example, from about 0.5 liters per minute to about 10 liters per minute, such as from about 1 liter per minute to about 5 liters per minute.

Although FIG. 3 illustrates a single induction coil 90 embedded behind the surface of the edge guide 80' , embodiments herein include wherein at least two induction coils (not shown) are embedded behind the surface of the edge guide Their embodiments. The induction coils can each be connected to an induction heating system that operates independently of each other or in cooperation with each other. For example, the at least two induction coils can be individually controlled, for example, by controlling the amount and frequency of alternating current supplied to each coil from the power supply and/or controlling the flow rate of coolant flowing through each coil.

Such induction when using at least two separately controlled induction coils The coil may be positioned such that, for example, a first one of the at least two separately controlled induction coils is positioned in the first region, and a second one of the at least two separately controlled induction coils is Located in the second area. For example, the coils can be positioned such that the power supplied to the first induction coil is greater than at least 10% of the power supplied to the second induction coil, such as greater than at least 20%, and further such as greater than at least 30%, and more Further such as greater than at least 40%, and yet further such as greater than at least 50%. For example, the power supplied to the first induction coil may be in the range of 7.5 kW to 50 kW, and the power supplied to the second induction coil may be in the range of 5 kW to 25 kW.

For example, when at least two induction coils are embedded in the edge guide Behind the surface, in some exemplary embodiments, the inductive coils may be embedded behind different surface regions of the edge guide to be compared to the second surface region of the edge guide at the edge guide Different temperature characteristics or profiles are provided on the first surface area. This different temperature characteristic or profile can be made possible, for example, by supplying different amounts of power to at least two induction coils. For example, the coils may be embedded behind the edge guide such that the first one of the at least two separately controlled induction coils is embedded behind the first surface area of the edge guide, and at least two Second induction coil of separately controlled induction coil Embedded behind the second surface region of the edge guide, and wherein the power supplied to the first induction coil is greater than the power supplied to the second induction coil by at least 10%, such as greater than at least 20%, and further such as greater than at least 30%, And further, such as greater than at least 40%, and yet further such as greater than at least 50%. For example, the power supplied to the first induction coil may be in the range of 7.5 kW to 50 kW, and the power supplied to the second induction coil may be in the range of 5 kW to 25 kW.

For example, the coils can be embedded behind the edge guides to The first surface is caused to have a maximum temperature greater than the second surface by at least 10 °C, such as greater than at least 25 °C, and further such as greater than at least 50 °C, and further such as greater than at least 100 °C. In a preferred embodiment, the first surface is on the lower portion of the edge guide and the second surface is on the upper portion of the edge guide.

Although only one edge guide 80' is illustrated as assembled to the forming wedge 62' in Figure 3, it should be understood that the second inductively heated edge guide (similar to the edge guide 80' ) can also be assembled. On the opposite end (not shown) of the shaped wedge.

Additionally, while Figure 3 illustrates a single source of coolant, the coolant is supplied to and returned to the single source of coolant (e.g., cooler 400 ) such that the coolant circulates continuously within the induction heating system 1000 , it will be understood that Embodiments herein may include where the coolant is supplied from sources other than the chiller 400 (including more than one source (eg, a combination of chiller 400 and house water)) and some, if not all, of the coolant is after the cycle None of the embodiments that are returned to the cooler 400 by the input line 402 and the output line 452 .

Although the embodiments described above include contacts in which the edge guides are in contact Embodiments of the molten glass are directly heated by induction, but embodiments disclosed herein also include at least one other portion of the edge guide (eg, not touching portions of the molten glass) and/or very At least one other sensitive material adjacent the edge guides is inductively heated by the embodiment of the direct contact, wherein heat is transferred from at least one other edge guide and/or other sensitive material to one of the edge guides contacting the molten glass Or multiple parts. In this manner, the portion of the edge guide that contacts the molten glass is still heated by induction, but in a more indirect manner than in the embodiments described above. The induction heating system shown in Fig. 3 can be applied to the more indirect induction heating method.

5A and 5B schematically illustrate perspective views of an alternate embodiment of an induction heating system assembly as disclosed herein. The embodiment illustrated embodiment, the induction coil 92 is replaced by a slotted conductive sheet, the slotted conductive plate 92 is configured to conduct an alternating current supplied from the AC power supply of FIG. 5A and second 5B in FIG. The coolant can be circulated through the coolant conduit, such as the cylindrical coolant conduit 94 shown in Figure 5A or the rectangular coolant conduit 96 as shown in Figure 5B. The trough-type conductive plate 92 can be configured to be embedded behind the edge guide surface that is in contact with the molten glass, such as configured to fit tightly beneath the edge guide surface that is in contact with the molten glass. At least one thermal insulation layer (not shown) may be between the inner edge guide surface and the slotted conductive plate. The trough conductive plate 92 can also be configured to be easily attached or detached within the induction heating system. The trough-type conductive plate 92 may comprise at least one material selected from the group consisting of copper, nickel, platinum, gold, silver, and alloys comprising at least one of the foregoing. In a particularly preferred embodiment, the slotted conductive plate 92 comprises copper. A coolant conduit, such as a cylindrical coolant conduit 94 or a rectangular coolant conduit 96 , can comprise at least one material selected from the group consisting of copper, nickel, platinum, gold, silver, and An alloy comprising at least one of the above. In a particularly preferred embodiment, the coolant conduit comprises copper.

6A and 6B are schematic cross-sectional views and perspective views, respectively, of another exemplary embodiment as disclosed herein. In the embodiment shown in Figures 6A and 6B, the edge guide 80' includes a backing plate 180 . In certain exemplary embodiments, the backing plate 180 can be made of the same material as the edge guide 80' , such as at least one material selected from the group consisting of platinum, rhodium, palladium, iridium, and An alloy comprising at least one of the above. In a particularly preferred embodiment, the backing plate 180 comprises platinum. The backing plate 180 has an inner surface 182 and an outer surface 184 , and the backing plate 180 is preferably positioned such that the molten glass does not substantially flow on the outer surface of the backing plate 180 .

Backplane 180 'to direct induction heating, the induction coil 90' by the induction coil 90 is positioned behind at least a portion of the outer surface 184. Next, heat is transferred from the backing plate 180 to the surface of the edge guide 80' that directly contacts the molten glass.

Induction coil 90 'should preferably be embedded in the rear surface 184 outside the backplane (180), an outer surface 184 as close as possible. For example, in a preferred embodiment, the induction coil 90' can be configured such that the portion of the coil closest to the outer surface 184 is less than 10 millimeters, such as less than 5 millimeters, and further such as less than 2 millimeters.

Heat transfer preferred embodiment, the thermal insulating material 190 may be positioned outside of the back plate 180 surface 184 and the induction coil 90 'between the back plate 180 so as to minimize the induction coil 90' between the some. Examples of suitable thermal insulation materials include those comprising at least one of alumina, aluminosilicate fibers, organic binders, and inorganic binders such as, for example, KVS high temperature vacuum formed sheets and shapes available from Rath. material.

Embodiments disclosed herein include embodiments in which heat transfer between the backing plate 180 and the edge guide 80' is directly contacted with one or more surfaces of the molten glass. For example, in some embodiments, at least a portion of the region between the inner surface of the backsheet and the inner surface of the edge guide that contacts the molten glass may be filled with a material having thermal conductivity (kappa), wherein κ is at least 10 W/(m.K) at 25 ° C, such as at least 20 W/(m.K) at 25 ° C, and further such as at least 30 W/(m.K) at 25 ° C, and further Such as at least 50 W/(m.K) at 25 °C, and yet further such as at least 100 W/(m.K) at 25 °C, and even further such as at least 200 W/(m.K) at 25 °C. , including from 10 W/(m.K) to 500 W/(m.K) at 25 ° C, and further including from 20 W/(m.K) to 400 W/(m.K) at 25 ° C, and further It is included from 30 W/(m.K) to 300 W/(m.K) at 25 °C.

Figure 7 is a schematic illustration of a perspective view of an edge guide 80' having a backing plate 180 , wherein the area between the inner surface 182 of the backing plate and the inner surface of the edge guide 80' that contacts the molten glass is filled with A thermally conductive material in the form of thermally conductive beads 200 . The presence of the thermally conductive beads 200 substantially increases the conductivity (and overall) heat transfer between the backing plate 180 and the surface of the edge guide that contacts the molten glass.

Thermally conductive beads 200 preferably comprise a material having thermal conductivity (κ), wherein κ is at least 10 W/(m.K) at 25 ° C, such as at least 20 W/(m.K) at 25 ° C, and Further such as at least 30 W/(m.K) at 25 °C, and further such as at least 50 W/(m.K) at 25 °C, and yet further such as at least 100 W/(m.K at 25 °C And, even further such as at least 200 W/(m.K) at 25 ° C, including from 10 W/(m.K) to 500 W/(m.K) at 25 ° C, and further including at 25 ° C 20 W/(m.K) to 400 W/(m.K), and further including from 30 W/(m.K) to 300 W/(m.K) at 25 °C. The thermally conductive beads may, for example, be selected from the group consisting of alumina and cerium oxide.

Although Figure 7 illustrates a thermally conductive material in the form of beads, it should be understood that embodiments herein may include other types or configurations of thermally conductive materials, such as particulate thermally conductive materials, non-spherical thermally conductive materials, and solid thermal conduction of a single structure. a material, such as a thermally conductive block, shaped to be compatible with the inner surface of the edge guide 80' to provide sufficient heat transfer between the backing plate 180 and the surface of the edge guide that contacts the molten glass and/or Heat transfer is provided between the backing plate 180 and the surface of the edge guide that contacts the molten glass such that the temperature of the edge guide contacting the molten glass coincides with the predetermined temperature gradient profile.

In the embodiment, the promotion of the back plate 180 and the edge guiding can be further improved. The heat transfer between the surfaces of the contact molten glass, wherein at least one of the inner surface 182 of the backing plate 180 and the inner surface of the edge guide contacting the molten glass is configured to have a relatively high emissivity (ε ) such as where 0.5 ≦ ε ≦ 1.0, such as 0.6 ≦ ε ≦ 1.0, further such as 0.7 ≦ ε ≦ 1, further such as 0.8 ≦ ε ≦ 1, and further such as 0.9 ≦ ε ≦ 1.

For example, in some embodiments, the inner surface and edge of the backing plate At least one of the inner surfaces of the guide member contacting the molten glass is coated with a high emissivity coating, such as a coating having an emissivity ([epsilon]), wherein 0.5 ≦ ε ≦ 1.0, such as 0.6 ≦ ε ≦ 1.0, Further, such as 0.7 ≦ ε ≦ 1, further such as 0.8 ≦ ε ≦ 1, and further such as 0.9 ≦ ε ≦ 1. In some preferred embodiments, Both the inner surface of the backing plate and the inner surface of the edge guide contacting the molten glass are coated with a high emissivity coating, such as a coating having an emissivity ([epsilon]), wherein 0.5 ≦ ε ≦ 1.0, such as 0.6 ≦. ≦ ≦ 1.0, further such as 0.7 ≦ ε ≦ 1, further such as 0.8 ≦ ε ≦ 1, and further such as 0.9 ≦ ε ≦ 1. Examples of high emissivity materials and coatings include, for example, at least one coating comprising a material selected from the group consisting of alumina, zirconia, and mixtures of the foregoing and multi-molecules Floor. High emissivity coatings can be applied, for example, by plasma spray techniques or flame spray techniques.

By using thermally conductive materials and/or high emissivity coatings, in some examples In an embodiment, the heat transfer from the back sheet to the edge guide contacting one or more surfaces of the molten glass may be promoted such that the temperature difference between the back sheet and the edge guide contacting the surface of the molten glass is less than 200 ° C, such as less than 150 ° C, and further such as less than 100 ° C, including from 50 ° C to 200 ° C, and further including from 100 ° C to 150 ° C. For example, if the temperature of the backing plate is about 1300 ° C, the temperature of the edge guide contacting the surface of the molten glass may be at least 1100 ° C, such as at least 1150 ° C, and further such as at least 1200 ° C, and further such as at least 1250 ° C .

Embodiments herein can provide advantages over minimizing devitrified glass at the edges Advantages of other methods of forming on the guide, such as the use of, for example, resistive heaters near the edge guides (heat transfer from the resistive heater to the edge guide based on convection and radiation). These methods are not sufficient to transfer sufficient heat to the edge guides to achieve the proper edge guide temperature necessary to substantially minimize devitrification within the necessary physical space constraints. These methods may not enable precise temperature control of the edge guides, which can be implemented according to this article. Example implementation. In addition, the additional components used in such methods, such as electrical resistance heaters, etc., can take up a significant amount of critical physical space in the vicinity of the draw and can result in substantial defects in the manufacturing components and equipment located in the vicinity of the remote guides (and Unnecessary heating.

It will be apparent to those skilled in the art that various modifications and changes can be made to the embodiments described herein without departing from the spirit and scope of the invention. The modifications and variations of the various embodiments described herein are intended to be included within the scope of the appended claims.

Claims (27)

A fusion drawing method for manufacturing a glass sheet, the method comprising the steps of: flowing a molten glass over a portion of a forming wedge that is inclined toward a downwardly inclined forming surface, the downwardly inclined forming surface portion being along a downstream direction Converging to form a portion; flowing the molten glass over one of the edge guides intersecting at least one of the pair of downwardly inclined forming surface portions; at least by directly heating the edge guide with an induction coil Maintaining a minimum temperature of the edge guide contacting at least a portion of a surface of the molten glass by heating the edge guide to be greater than a predetermined amount, the induction coil being embedded in the edge contact with the molten glass The surface of the piece is behind; and the molten glass is drawn from the root of the shaped wedge to form a piece of glass. The method of claim 1, wherein the minimum temperature at which the edge guide contacts at least a portion of the surface of the molten glass is maintained above a liquidus temperature of the molten glass. The method of claim 1, wherein the minimum temperature at which the edge guide contacts at least a portion of the surface of the molten glass is maintained above 1150 °C. The method of claim 1, wherein the edge guide comprises a backing plate, the backing plate is directly heated by induction, and an inductive coil is positioned behind an outer surface of the backing plate. The method of claim 4, wherein at least a portion of a region between an inner surface of the backing plate and the edge guide contacting an inner surface of the molten glass is filled with a thermal conductivity (κ) One material, wherein κ is at least 10 W/(m.K) at 25 °C. The method of claim 4, wherein at least one of an inner surface of the backing plate and the inner surface of the edge guide contacting the molten glass is coated with a coating having an emissivity (ε), where 0.5 ≦ ε ≦ 1.0. The method of claim 1, wherein the edge guide comprises at least one material selected from the group consisting of platinum, rhodium, palladium, rhodium, and at least one of the foregoing. One of the alloys. The method of claim 1, wherein the edge guide comprises an alloy of platinum and tin. The method of claim 1, the method further comprising the step of using a controller to provide management control of the minimum temperature of the edge guide contacting at least a portion of the surface of the molten glass. The method of claim 1, wherein the minimum temperature of the edge guide contacting at least a portion of the surface of the molten glass can be varied at a rate of at least 10 ° C per minute at a temperature of at least 1000 ° C. The method of claim 1 wherein the edge guide is inductively heated by at least two separately controlled induction coils. The method of claim 11, wherein one of the at least two separately controlled induction coils is positioned in a first region and one of the at least two individually controlled induction coils The second induction coil is positioned in a second region, and wherein the power supplied to the first induction coil is greater than the power supplied to the second induction coil by at least 10%. The method of claim 1, wherein the edge guide is directly inductively heated by a slotted conductive plate that is embedded behind the surface of the edge guide that contacts the molten glass. An apparatus for pulling down a glass sheet, the apparatus comprising: a forming wedge having a pair of downwardly inclined forming surface portions, the downwardly inclined forming surface portions being in the forming wedge Converging at the bottom to form a portion and defining a draw line for the molten glass along the draw line; and an edge guide that contacts the pair to slope downwardly At least one of the shaped surface portions; Wherein the edge guiding member comprises an induction heating system component, the induction heating system component having at least one of an induction coil and a slotted conductive plate positioned behind a surface of the edge guiding member for sensing The edge guide is heated to maintain a minimum temperature of the edge guide contacting at least a portion of a surface of the molten glass above a predetermined amount. The apparatus of claim 14, wherein the minimum temperature at which the edge guide contacts at least a portion of the surface of the molten glass is maintained above a liquidus temperature of the molten glass. The apparatus of claim 14, wherein the minimum temperature at which the edge guide contacts at least a portion of the surface of the molten glass is maintained above 1150 °C. The device of claim 14, wherein the edge guide is directly heated by induction, and at least one of an induction coil and a slotted conductive plate is embedded in the edge guide to contact the molten glass. Behind the surface. The device of claim 14, wherein the edge guide comprises a backing plate, the backing plate is directly heated by induction, and an inductive coil is positioned behind an outer surface of the backing plate. The apparatus of claim 18, wherein an inner surface of one of the back sheets contacts at least an area between the inner surface of the molten glass and the edge guide A portion is filled with a material having a thermal conductivity (κ), wherein κ is at least 10 W/(m.K) at 25 °C. The apparatus of claim 18, wherein an inner surface of one of the back sheets and at least one of the inner surface of the edge guide contacting the molten glass are coated with a coating having an emissivity (ε), where 0.5 ≦ ε ≦ 1.0. The apparatus of claim 14, wherein the edge guide comprises at least one material selected from the group consisting of platinum, rhodium, palladium, rhodium, and at least one of the foregoing One of the alloys. The device of claim 14, wherein the edge guide comprises an alloy of platinum and tin. The apparatus of claim 14 wherein the minimum temperature of the edge guide contacting at least a portion of the surface of the molten glass is variable at a rate of at least 1000 ° C at a rate of at least 10 ° C per minute. The device of claim 14, wherein the edge guide comprises at least two separately controlled induction coils. The device of claim 24, wherein one of the at least two separately controlled induction coils is positioned in a first region and one of the at least two individually controlled induction coils Two induction coils are positioned in a second In the area, and wherein the power supplied to the first induction coil is greater than the power supplied to the second induction coil by at least 10%. The device of claim 14, wherein the induction coil is coated, insulated, sheathed or embedded with at least one material that provides thermal, mechanical or corrosion protection. The device of claim 14, wherein the induction coil is configured such that the coil extends through at least three regions, the first region being one of the centers closest to the center of the edge guide, and the other two regions On either side of the central region, wherein the portion of the coil that is closest to the center of the edge guide is configured to move forward relative to the portion of the coil on either side of the central region protruding.