JP5820395B2 - Apparatus and method for fusing and drawing glass ribbons - Google Patents

Description

Explanation of related applications

  This application claims the benefit of priority of US Provisional Patent Application No. 61 / 296,240, filed Jan. 19, 2010.

  The present invention relates generally to an apparatus and method for fusing and stretching a glass ribbon, and more specifically to an apparatus and method for fusing and stretching a glass ribbon using a heating device and a cooling device.

  A glass manufacturing system is generally used for molding various glass products such as LCD plate glass. It is known that molten glass is flowed downward on a forming wedge, and further a glass ribbon is drawn from the bottom of the forming wedge to produce a plate glass. In order to help achieve the desired glass ribbon width and edge bead properties, edge guides are often provided at the opposite ends of the forming wedge.

  The following presents a simplified summary of the disclosure in order to provide a basic understanding of some example embodiments described in the detailed description.

  In one embodiment, the fusion draw method comprises flowing molten glass over a pair of downwardly inclined forming surface portions of a forming wedge, the downwardly inclined forming surface portions joining along a downstream direction to form a bottom portion. Forming steps. The method further includes flowing molten glass over the edge guide member intersecting at least one of the pair of downwardly inclined forming surface portions. The method further includes the step of drawing the glass ribbon from the bottom, wherein the edge of the glass ribbon is formed by molten glass flowing away from the edge guide member. The method uses a heating device to heat the contact surface of the molten glass that is in contact with the edge guiding member, and uses a cooling device to flow the glass ribbon away from the edge guiding member. And depriving the part of heat.

  In another example embodiment, an apparatus for fusing and drawing glass ribbons includes a forming wedge having a pair of downwardly inclined forming surface portions that merge along a downstream direction to form a bottom. The apparatus further includes an edge guide member that intersects at least one of the pair of downwardly inclined forming surface portions. The apparatus is further configured to heat the contact surface of the molten glass that is in contact with the edge guide member and to remove heat from the portion of the glass ribbon that has flowed away from the edge guide member. And a cooling device.

  A first exemplary aspect of the invention relates to a fusion draw method, the method comprising flowing molten glass over a pair of downwardly inclined forming surface portions of a forming wedge, wherein the downwardly inclined forming surface portion is Merging along a downstream direction to form a bottom; flowing molten glass over an edge guide member intersecting at least one of a pair of downwardly inclined forming surface portions; Stretching from the bottom, wherein the edge of the glass ribbon is formed by molten glass flowing away from the edge guiding member; using a heating device to contact the edge guiding member Heating the contact surface of the molten glass; and using a cooling device to remove heat from the portion of the glass ribbon that has flowed away from the edge director. Including up, a.

  In a particular embodiment of the first aspect of the invention, the heating device maintains the contact surface of the molten glass in contact with the edge guiding member at a temperature above the liquidus temperature of the molten glass.

  In certain embodiments of the first aspect of the present invention, the method includes maintaining the temperature of the molten glass at a location downstream of the bottom and below the baggy warp temperature of the molten glass.

  In certain embodiments of the first aspect of the invention, the cooling device causes the temperature of the edge of the glass ribbon to decrease from the edge of the glass ribbon below the bottom at a faster rate than the temperature inside the glass ribbon. , Take heat preferentially.

  In a specific embodiment of the first aspect of the present invention, the cooling device provides more heat than the heating device provides to the contact surface of the molten glass that is in contact with the edge guiding member, below the bottom. Take away from the edge.

  In certain embodiments of the first aspect of the invention, the method further comprises shielding the heating area of the heating device from the cooling area of the cooling device.

  In a particular embodiment of the first aspect of the present invention, the heating device maintains the temperature of the contact surface of the molten glass that is in contact with the edge guiding member using an external heater that operates outside the edge guiding member. To do.

  In a particular embodiment of the first aspect of the present invention, the heating device maintains the temperature of the contact surface of the molten glass in contact with the edge induction member using an internal heater that operates inside the edge induction member. To do.

  In certain embodiments of the first aspect of the present invention, the cooling device includes a fluid nozzle that draws heat from the edge of the glass ribbon at a location downstream of the edge guide member.

  In certain embodiments of the first aspect of the invention, the method further comprises controlling at least one of the heating device and the cooling device with a control system.

  In certain embodiments of the first aspect of the invention, the method includes sensing temperature and further using the sensed temperature to provide feedback to the control system.

  A second exemplary aspect of the invention relates to an apparatus for fusing and stretching a glass ribbon, the apparatus including a pair of downwardly inclined forming surface portions that merge along a downstream direction to form a bottom. A forming wedge; an edge guide member intersecting at least one of a pair of downwardly inclined forming surface portions; a heating device configured to heat a contact surface of the molten glass in contact with the edge guide member; And a cooling device configured to take heat away from the portion of the glass ribbon that has flowed away from the edge guiding member.

  In a particular embodiment of the second aspect of the present invention, the heating device is configured to maintain the contact surface of the molten glass in contact with the edge guiding member at a temperature above the liquidus temperature of the molten glass. Yes.

  In certain embodiments of the second aspect of the present invention, the cooling device causes the temperature of the glass ribbon edge to decrease at a faster rate than the temperature inside the glass ribbon from the edge of the glass ribbon below the bottom. , Configured to take heat away preferentially.

  In a particular embodiment of the second aspect of the present invention, the cooling device provides more heat than the heating device provides to the contact surface of the molten glass in contact with the edge guiding member, below the bottom. It is configured to take away from the edge.

  In certain embodiments of the second aspect of the invention, the apparatus includes a heat shield provided between the heating area of the heating device and the cooling area of the cooling device.

  In certain embodiments of the second aspect of the invention, the apparatus includes a control system configured to control at least one of the heating device and the cooling device.

  In certain embodiments of the second aspect of the present invention, the control system includes a controller and a temperature sensor configured to provide feedback to the controller.

  In certain embodiments of the second aspect of the present invention, the control system prioritizes from the glass ribbon edge below the bottom so that the temperature of the glass ribbon edge decreases at a faster rate than the temperature inside the glass ribbon. It is configured to control the cooling device so as to take heat away.

  In certain embodiments of the second aspect of the present invention, the control system provides more heat from the heating device to the glass ribbon below the bottom than the heating device provides to the contact surface of the molten glass in contact with the edge guiding member. The cooling device is configured to operate at least one of the heating device and the cooling device so that the cooling device takes away from the edge.

  These and other aspects are better understood when the following detailed description is read with reference to the accompanying drawings.

Schematic diagram of an apparatus for fusing and drawing glass ribbons FIG. 2 is a cross-sectional perspective view of the device taken along line 2-2 of FIG. 1 and shows a portion of the device of the first example. Side view showing part of the device of the second example Side view showing part of the device of the third example

  Several examples will now be described in more detail below, with reference to the accompanying drawings showing example embodiments. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. However, aspects may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

  FIG. 1 shows a schematic diagram of an apparatus 101 for fusing and stretching a glass ribbon 103 for the subsequent processing of generating a glass sheet. The apparatus 101 can include a dissolution vessel 105 configured to receive batch material 107 from a storage vessel 109. The batch material 107 may be introduced using a batch delivery device 111 that is moved by a motor 113. An optional controller 115 may be configured to operate the motor 113 to introduce the desired amount of batch material 107 into the dissolution vessel 105 as indicated by arrow 117. It is also possible to measure the level of the glass melt 121 in the upright pipe 123 using the glass metal probe 119 and to transmit the measured information to the controller 115 via the communication line 125.

  The apparatus 101 may further include a clarification tank 127 such as a clarification pipe. The clarification tank 127 may be positioned downstream of the dissolution tank 105 and connected to the dissolution tank 105 using the first connection pipe 129. A mixing tank 131 such as a stirring chamber may be positioned downstream of the clarification tank 127, and a delivery tank 133 such as a bowl may be positioned downstream of the mixing tank 131. As shown in the drawing, the clarification tank 127 may be connected to the mixing tank 131 by the second connection pipe 135, and the mixing tank 131 may be connected to the delivery tank 133 by the third connection pipe 137. As further shown, a downcomer 139 may be provided to deliver the glass melt 121 from the delivery tank 133 to the inlet 141 of the molding tank 143. As shown in the figure, the dissolution tank 105, the clarification tank 127, the mixing tank 131, the delivery tank 133, and the molding tank 143 are examples of glass melting stations, and these may be positioned in series along the apparatus 101.

  The dissolution bath 105 is typically made from a refractory material such as refractory (eg, ceramic) brick. Components that the apparatus 101 may further include are typically made from platinum or a platinum-containing metal such as platinum rhodium, platinum iridium, and mixtures thereof, but molybdenum, palladium, rhenium, tantalum, titanium, tungsten, It may contain refractory metals such as ruthenium, osmium, zirconium, and alloys thereof, and / or zirconium dioxide. The platinum-containing components include a first connecting pipe 129, a clarifying tank 127 (for example, a clarifying pipe), a second connecting pipe 135, an upright pipe 123, a mixing tank 131 (for example, a stirring chamber), a third connecting pipe 137, One or more of a delivery tank 133 (eg, a bowl), a downcomer 139, and an inlet 141 may be mentioned. The forming vessel 143 is similarly made from a refractory material, and the forming vessel 143 is designed to form the glass ribbon 103.

  2 is a cross-sectional perspective view of the device 101 of FIG. 1 taken along line 2-2. As shown, the forming vessel 143 includes a forming wedge 201 having a pair of downwardly inclined forming surface portions 207 and 209, and these forming surface portions 207 and 209 extend between opposing ends of the forming wedge 201. Exist. The pair of downward inclined molding surface portions 207 and 209 merge along the downstream direction 211 to form the bottom portion 213. The glass ribbon 103 may be stretched in the downstream direction 211 along a stretched surface 215 that extends through the bottom 213. As illustrated, the extending surface 215 may bisect the bottom 213, but may extend in other orientations relative to the bottom 213.

  The forming tank 143 may include one or more edge guiding members that intersect at least one of the pair of downward inclined forming surface portions 207 and 209. In a further example, the one or more edge guide members may intersect both the downwardly inclined forming surface portions 207, 209. In a further example, an edge guide member may be provided at each of the opposing ends of the forming wedge 201, at which time the edge of the glass ribbon 103 is formed by molten glass flowing away from the edge guide member. For example, as shown in FIG. 2, the edge guide member 217 may be installed at the first opposing end 203, and the same second edge guide member (not shown) may be installed at the second opposing end (not shown). ). Each edge guide member can also be configured to intersect with both of the downwardly inclined molding surface portions 207 and 209. Each edge guide member 217 may be substantially identical to each other, but in further examples may have different characteristics. In accordance with aspects of the present disclosure, various forming wedge and edge guide member configurations can be used. For example, molding wedges and edge guide members that may be used with aspects of the present disclosure are described in US Pat. Nos. 3,451,798, 3,537,834, 7,409, 839 and / or U.S. Provisional Patent Application No. 61 / 155,669 filed on Feb. 26, 2009, each of which is incorporated herein by reference in its entirety. It is.

  FIG. 2 illustrates just one example edge guide member 217 that may be used with aspects of the present disclosure. The first edge guide member 217 will be discussed with the understanding that the second edge guide member (not shown) may be similar or identical to the first edge guide member 217 in some examples. Providing the same edge guide member can be beneficial in providing a uniform glass ribbon, but the edge to provide a variety of glass sheet properties and / or to adapt to various forming vessel configurations The guide member may have different characteristics.

  FIG. 2 shows the first side of the first edge guide member 217 positioned relative to the first downwardly inclined forming surface portion 207 of the forming wedge 201. Although not shown, the first edge guide member 217 further includes a second side portion that is positioned with respect to the second inclined molding surface portion 209 of the molding wedge 201. The second side portion of the first edge guiding member 217 is a mirror image of the first side portion with respect to the extending surface 215 that bisects the bottom portion 213. As shown, the first side includes a first surface 219 that intersects a first downwardly inclined forming surface portion 207 of the forming wedge 201. Although not shown, the second side portion of the first edge guide member 217 similarly includes substantially the same surface that intersects the second inclined forming surface portion 209 of the forming wedge 201.

  Each opposing end of the forming wedge 201 may be provided with a retaining block 221 designed to help position the corresponding first and second edge guide members 217 laterally. Optionally, as shown, the first edge guide member 217 may include an upper portion 223 and a lower portion 225. In some examples, the lower portion 225 may tie the first edge guide member 217 to the first opposing end 203 and the second edge guide member to the second opposing end (not shown). Combining these edge guide members 217 can be beneficial in simplifying the assembly of the edge guide members 217 into the forming wedge 201. In a further example, each upper portion 223 of these edge guide members 217 may be provided separately. For example, the first edge guide member 217 may be separated from the second edge guide member, and the first edge guide member 217 may be separated from the pair of downward inclined molding surface portions 207 and 209 of the molding wedge 201, respectively. May be assembled independently. In certain configurations, providing an uncoupled upper portion 223 can simplify the manufacture of the edge guide member 217. Each edge guide member 217 can have various orientations and shapes by providing various surfaces to the forming wedge 201.

  The apparatus 101 for fusing and drawing glass ribbons may further include at least one edge roller assembly. The edge roller assembly includes a pair of edge rollers configured to engage corresponding edges of the glass ribbon as the glass ribbon is drawn from the bottom 213 of the forming wedge 201. This pair of edge rollers helps to properly finish the edges of the glass ribbon. Finishing with an edge roller achieves the desired edge characteristics, and the appropriateness of the edge portion of the molten glass that is pulled from the opposing surface of the edge guide member associated with the pair of downwardly inclined forming surface portions 207, 209 Fusion becomes possible. As shown in FIG. 2, a first edge roller assembly 227 is associated with the first edge guide member 217 and a second edge roller assembly (not shown) is associated with the second edge guide member. Each edge roller assembly 227 may be substantially identical to each other, but in further examples, these edge roller pairs may have different characteristics.

  FIG. 2 illustrates an example edge roller assembly that may be used with aspects of the present disclosure. The first edge roller assembly 227 will be discussed with the understanding that the second edge roller assembly (not shown) may be similar or identical to the first edge roller assembly 227 in some examples. As shown in FIG. 2, the first edge roller assembly 227 includes a first edge roller pair 229 including a first edge roller 231 and a second edge roller 233. The edge rollers 231 and 233 are configured to engage simultaneously with the first surface and the second surface of the glass ribbon 103. The first edge roller assembly 227 further includes a first shaft 235 attached to the first edge roller 231 and a second shaft 237 attached to the second edge roller 233. The first shaft 235 and the second shaft 237 are configured to be rotatably driven by a motor (not shown).

  As schematically illustrated in FIG. 2, the device 101 may further include one or more heating devices 239. The heating device 239 is configured to heat the contact surface of the molten glass that is in contact with the first edge guiding member 217. In the illustrated example, the first heating device 239 may be positioned near the edge guiding member 217 as an external heating device. In one example, the external heating device may be configured to heat the back surface of the lower portion 225 of the first edge guiding member 217. As shown in FIG. 3, the heating device 339 can be positioned inside the edge guiding member, but the heating device can be positioned on the edge guiding member or in other locations in further examples. In practice, the heating device can be positioned in various three-dimensional positions with respect to the edge guiding member 217. Although one heating device may be provided as shown, in a further example multiple heating devices may be provided.

  The heating device can heat the contact surface of the molten glass that is in contact with the first edge guiding member 217 beyond the liquidus temperature of the molten glass. The liquidus temperature corresponds to the lower temperature range of the temperatures at which the glass remains melted without forming crystals. If some part of the molten glass falls to a temperature below the liquidus temperature, crystallized glass can result. The crystallized part of the glass is often referred to as devitrification in the molten glass, and this crystallized part is at a rate proportional to the temperature difference from the liquidus temperature when the glass falls below the liquidus temperature. It tends to accumulate. That is, in one example, the heating device 239 is configured to heat the contact surface of the molten glass that is in contact with the first edge guide member, thus reducing the rate at which devitrification accumulates on the edge guide member. In another example, the edge guide member 217 is maintained at a temperature above the liquidus temperature so that any devitrification buildup on the edge guide member is substantially reduced or not even accumulated. By eliminating the accumulation of arbitrary devitrification, an edge guiding member device that does not cause devitrification is obtained.

  Although it is desirable to reduce the accumulation of devitrification on the edge guiding member, when the heating device 239 operates in this manner, the viscosity of the molten glass also tends to decrease. As indicated by reference numeral 245 in FIG. 2, as the viscosity decreases, an undesirable decrease in the width of the glass ribbon 103 may occur.

  The apparatus 101 may further include one or more cooling devices 241 to mitigate the undesirable loss of glass ribbon 103 width. As schematically shown in FIG. 2, the cooling device 241 is configured to remove heat from the portion of the molten glass that has flowed away from the first edge guide member 217. The cooling device 241 can comprise a variety of devices, such as, but not limited to, a fluid dispensing device (eg, an orifice that forms an air jet), a relative hold held in proximity to the edge of the glass ribbon. Cold objects, radiant coolers, and / or multiple fluid nozzles.

  The configuration of the cooling device may operate in one or more different ways. For example, the cooling device 241 takes heat preferentially from the edge of the glass ribbon 103 below the bottom 213 so that the temperature of the edge of the glass ribbon 103 decreases at a faster rate than the temperature inside the glass ribbon. The cooling device 241 may be configured. In this example, the inside may include an intermediate portion such as a central portion disposed between the left and right edges of the glass ribbon 103 facing each other. Additionally or alternatively, the cooling device 241 may draw more heat from the edge of the glass ribbon 103 below the bottom 213 than the heating device 239 gives to the molten glass contact surface in contact with the edge guiding member. In addition, the cooling device 241 may be configured.

  Operating the cooling device 241 below the bottom 213 helps to mitigate the undesirable reduction in glass ribbon width that can occur when the heating device 239 is operated alone. That is, the heating device 239 can be used to reduce the formation of devitrification on the edge guide member, while the cooling device 241 can be used to continue the molten glass flowing away from the edge guide member. Undesirable loss of glass ribbon width, which can occur when the heating device 239 is used without cooling, can be mitigated.

  FIG. 3 shows a side view of a second example device 301 that includes a forming wedge 201 and the edge guide member 217 of FIG. In the example of FIG. 3, the heating device 339 is located in the edge guiding member 217. As further shown in FIG. 3, the device 301 may include a pair of edge gates 305 and a pair of center gates 307. Only one of the edge gates 305 and one of the central gates 307 is shown in this figure, and the other gate of each pair is located on the back side of the molten glass. The edge gate 305 and the center gate 307 are positioned below the lower portion 225 of the edge guide member 217 to help guide the flow of molten glass. Since the central portion of the molten glass is thinner than the edge portion of the molten glass, the pair of center gates 307 may be closer to the edge gate 305 pair. Due to the additional flow of molten glass from the edge guiding member 217, the pair of edge gates 305 cannot be as close as well.

  As further shown in FIG. 3, the first and second rollers 231, 233 may be actively cooled to help reduce the possibility of molten glass depositing on the edge rollers 231, 233. For example, as shown in FIG. 3, the inlet line 309 is configured to extend through the shafts 235 and the first and second rollers 231 and 233 have a cooling fluid (i.e., gas). Or liquid). The outlet line 311 also extends through each shaft 235, 237, which returns the heated liquid to the liquid supply 313. The hydraulic pump 315 draws a fluid from the liquid supply source, passes the fluid through the heat exchanger 317, removes the heat transferred from the first and second rollers 231, 233, and passes the fluid through the inlet line 309. The cooling of the first and second rollers 231 and 233 may be continued. This cooling can help reduce the likelihood of glass sticking to the rollers. In a further example, the rollers may be cooled faster to assist the cooling device 241.

  A device 401 of the third example is shown in FIG. As described above, the heating device 239 heats the contact surface of the molten glass that is in contact with the first edge guiding member 217. The cooling device 241 is configured to remove heat from the portion of the molten glass that has flowed away from the first edge guide member 217. Similarly, the apparatus 401 of the third example may further include a structure for cooling the rollers 231 and 233, or any other structure according to another example.

  In the third example of FIG. 4, an optional heat shield device is provided with the illustrated heat shield 411. If a heat shield 411 is provided, the heat shield 411 may be configured to shield the heating area associated with the heating device 239 from the cooling area associated with the cooling device 241. As further illustrated, a control system 419 may be provided to control at least one of the heating device 239 and the cooling device 241. The control system 419 can operate at least one of the heating device 239 and the cooling device 241 in various ways based on various conditions, such as, but not limited to, different. The thing which monitored the temperature of the molten glass in a position and the thing which monitored the width | variety of the glass ribbon 103 are mentioned. In one example, the control system 419 takes heat preferentially from the edge of the glass ribbon 103 below the bottom 213 so that the temperature of the edge of the glass ribbon 103 decreases at a faster rate than the temperature inside the glass ribbon 103. As such, the cooling device 241 may be controlled. Additionally or alternatively, the cooling device 241 may draw more heat from the edge of the glass ribbon 103 below the bottom 213 than the heating device 239 gives to the molten glass contact surface in contact with the edge guiding member. In addition, the control system 419 may be configured to operate at least one of the heating device 239 and the cooling device 241.

  In one example, the control system 419 may further include a controller 421 and at least one sensor 423. At least one sensor 423 is located on the edge guide member 217 in this example, but other positions are possible in further examples. The sensor may further include an infrared sensor positioned to sense temperature conditions associated with the edge guide member. The at least one sensor 423 is configured to sense a temperature associated with the molten glass near the edge guide member 217 and uses this sensed temperature to provide feedback control to the heating device 239 and the cooling device 241. The at least one sensor 423 can transmit the sensed temperature to the controller 421 through a wired connection or a wireless connection. The controller 421 is then configured to adjust the operation of the heating device 239 and / or the cooling device 241 in response to the sensed temperature. Additionally or alternatively, another sensor 425 may be associated with the cooling device 241 to sense the temperature condition of the edge of the glass ribbon 103. The sensor may include an infrared sensor, but other sensing devices may be provided in further examples. The sensor 425 is configured to sense a temperature associated with the edge of the glass ribbon 103, and the sensor 425 uses the sensed temperature to provide feedback to the controller 421. Based on this sensed feedback, the controller 421 can then operate the cooling device 241 to provide appropriate cooling conditions.

  In addition, the controller sends a signal along line 417 to activate a motor (not shown) to provide the desired thermal control between the heating area associated with heating device 239 and the cooling area associated with cooling device 241. The positioning of the heat shield 411 can be controlled to achieve.

  Here, a method for forming glass will be described with reference to the apparatus 401 including the edge guide member 217 of this example. It will be clear that similar or identical method steps may be carried out with further examples, for example as described throughout this application. Furthermore, the exemplary method of the present invention can further exclude and / or add steps. Further, unless otherwise noted, these steps may be performed simultaneously, sequentially, or in a different order, depending on the particular application.

  As shown in FIGS. 1-2 and 4, a method of forming glass with an example apparatus 401 that includes an edge guide member 217 is schematically illustrated. In the first example method, a fusion draw method is provided to produce the glass ribbon 103. The method includes flowing molten glass over a pair of downwardly inclined forming surface portions 207, 209 constituting the forming wedge 201. Here, the pair of downward inclined molding surface portions 207 and 209 merge at the bottom portion 213 below the molding wedge 201. This method involves flowing molten glass on a first edge guiding member 217 that intersects at least one of a pair of inclined forming surface portions 207 and 209, and flowing molten glass from the bottom 213 of the forming wedge 201. Stretching to form a glass ribbon 103. In this method, a heating device 239 is used to heat the contact surface of the molten glass that is in contact with the first edge guiding member 217, and a cooling device 241 is used to cool the first edge of the molten glass. And removing heat from the portion that has flowed away from the member 217. That is, the heating device 239 heats the contact surface of the molten glass that is in contact with the first edge guiding member 217 to reduce the accumulation of devitrification, and the cooling device 241 uses only the heating device 239. In order to reduce the loss of the width of the glass ribbon 103 that may occur in some cases and maintain the width, heat is taken from a position below the edge guide member 217. In one example, when the heating device 239 heats the contact surface of the molten glass that is in contact with the first edge guiding member 217, an external heater that operates outside the edge guiding member 217 is used. In another example, when the heating device 239 heats the contact surface of the molten glass that is in contact with the first edge guide member 217, an internal heater that operates inside the edge guide member 217 is used. When the cooling device 241 takes heat from the molten glass below the edge guide member 217, a fluid nozzle may be used in one example.

  This example method may include using the heating device 239 to heat the contact surface of the molten glass that is in contact with the first edge guiding member 217 beyond the liquidus temperature of the molten glass. The liquid phase temperature can correspond to the temperature at which the crystalline phase begins to develop. That is, in one example, the heating device 239 is configured to heat the contact surface of the molten glass that is in contact with the first edge guiding member 217 so as to reduce the rate at which devitrification accumulates on the edge guiding member 217. In another example, the edge guide member 217 is maintained at a temperature above the liquidus temperature so that any devitrification buildup on the edge guide member 217 is substantially reduced or not even accumulated. The additional heat flux required to completely eliminate devitrification accumulation ensures that no part of the surface of the edge guide member 217 operates below the liquidus temperature of the glass being molded. It is like. Thus, aspects of the present disclosure can reduce or eliminate devitrification accumulation that can affect the quality of the glass ribbon. In fact, if the layer of devitrification gets too thick, the flowing glass can become “bridged” to a fixed object in close proximity, causing serious operational problems. Sometimes. Accumulation of devitrification can also disrupt the fusion of two molten glass ribbons that are drawn from the bottom 213 of the downwardly inclined forming surfaces 207,209. If the fusion is disrupted at the edge location, bubbles may form in the bead or other defects may occur in the glass ribbon.

  This example method may include the step of mitigating the function of the heating device 239 by using the cooling device 241 to deprive a certain amount of heat flux. Using the heating device 239 to heat the contact surface of the molten glass that is in contact with the first edge guiding member 217 will result in a loss of width of the resulting glass ribbon 103, ie, reduction. The cooling device 241 can be operated to recover the lost portion of the width by depriving the heat flux of an amount corresponding to the amount of heat flux applied by the heating device 239. In one example, the amount of heat flux added and subsequently deprived can be estimated from a glass ribbon formation model. The glass ribbon formation model is capable of providing an indication of the resulting sheet size for various temperatures of the molten glass.

  In another example, the amount of heat flux applied and deprived can be measured during operation of the device. In one example, when the cooling device 241 is operated at various cooling rates, glass ribbons with different width losses can be obtained by causing different attenuation in the molten glass. Based on modeling techniques, it has been found that when the cooling device 241 is operated at various cooling rates, the resulting loss of glass ribbon width can be reduced to about 57 mm. In another modeling example where a relatively high cooling rate was used, it was found that the resulting loss of glass ribbon width could be reduced to about 6 mm. In yet another modeling example where the cooling rate used was relatively large, the modeling results showed that the glass ribbon width increased by about 11 mm.

  The example method may further include maintaining the temperature of the molten glass at a position below the bottom 213 and below the buggy warp temperature of the molten glass. The buggy warp temperature represents the maximum temperature allowed on the free ribbon before the buggy warp condition is seen. The buggy warp temperature can vary depending on the local mass flow rate and glass composition as well as the cooling curve in the molten glass region. When the buggy warp is physically described, the viscosity of the molten glass is reduced because the temperature of the molten glass exceeds the buggy warp temperature. When in the buggy warp state, the viscosity of the molten glass has decreased to a stage where the pulling roller (not shown) can no longer be pulled. In addition, when in the buggy warp state, the flow of glass emerging from the forming wedge is a purely rectangular sheet that is pulled to a certain thickness by a pulling roller located far down in the plane. There is a possibility of starting to cross the flow. In one example method, the heating device 239 maintains the temperature of the edge of the molten glass passing over the edge guide member 217 within a range of about 3010 ° C. to about 1200 ° C. This temperature range is maintained at a temperature exceeding the liquidus temperature of the molten glass at a position below the bottom, such as 1200 ° C., while maintaining the molten glass in contact with the first edge guiding member, such as 3010 ° C. The temperature of the molten glass may be equivalent to that further maintained at a temperature lower than the buggy warp temperature. In this example method, this temperature can be maintained by using one of the heating device 239 and the cooling device 241, or by using both the heating device 239 and the cooling device 241.

  As another alternative, the example method may further include shielding the heating area of the heating device 239 from the cooling area of the cooling device 241. Shielding the heating area from the cooling area can be achieved using the heat shield 411 shown in FIG. The heat shield 411 may be configured to help control heat transfer between the heating region and the cooling region.

  This example method may further include the step of controlling at least one of the heating device 239 and the cooling device 241 with the control system 419. The control system 419 operates at least one of the heating device 239 and the cooling device 241 in various manners based on various conditions including the temperature of the molten glass at different positions and the width of the glass ribbon 103. be able to. In one example, the control system 419 may include sensing or measuring a temperature associated with the molten glass and using the sensed temperature to provide feedback control to the control system 419.

  It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the claimed invention.

201 Molding wedges 207, 209 Downward inclined molding surface portion 213 Bottom portion 217 Edge guide member 227 Edge roller assembly 231, 233 Edge roller 239, 339 Heating device 241 Cooling device 411 Heat shield 419 Control system 421 Controller 423, 425 Sensor

Claims (10)

In the fusion draw method,
Molten glass, a pair downwardly inclined forming surface portion of the molding wedges, steps to flow downwardly inclined forming surface on the portion forming the bottom joins along the downstream direction,
Flowing the molten glass over an edge guiding member intersecting at least one of the pair of downwardly inclined molding surface portions;
Stretching a glass ribbon from the bottom, wherein the edge of the glass ribbon is formed by molten glass flowing away from the edge guiding member;
Heating the contact surface of the molten glass in contact with the edge guiding member using a heating device; and
Using a cooling device to remove heat from the portion of the glass ribbon that has flowed away from the edge guiding member;
A method comprising the steps of:   The method according to claim 1, wherein the heating device maintains the contact surface of the molten glass in contact with the edge guiding member at a temperature higher than a liquidus temperature of the molten glass.   The method according to claim 1 or 2, further comprising the step of maintaining the temperature of the molten glass at a position downstream of the bottom and below the buggy warp temperature of the molten glass.   The cooling device preferentially draws heat from the edge of the glass ribbon below the bottom so that the temperature of the edge of the glass ribbon decreases at a faster rate than the temperature inside the glass ribbon. 4. A method according to any one of claims 1 to 3, characterized in that   The cooling device takes more heat from the edge of the glass ribbon below the bottom than the heat given by the heating device to the contact surface of the molten glass in contact with the edge guiding member. 5. A method according to any one of claims 1 to 4, characterized in that:   The said heating apparatus maintains the temperature of the said contact surface of the said molten glass which is contacting with the said edge induction member using the external heater which operate | moves outside the said edge induction member. 5. The method according to any one of 5 to 5. An apparatus for fusing and stretching a glass ribbon,
A forming wedge comprising a pair of downwardly inclined forming surface portions that merge along the downstream direction to form a bottom;
An edge guide member intersecting at least one of the pair of downward inclined molding surface portions;
A heating device configured to heat a contact surface of the molten glass in contact with the edge guiding member; and
A cooling device configured to remove heat from a portion of the glass ribbon that has flowed away from the edge guiding member;
A device characterized by comprising:   The said heating apparatus is comprised so that the said contact surface of the said molten glass which is contacting with the said edge induction | guidance | derivation member may be maintained at the temperature exceeding the liquidus temperature of this molten glass. Equipment.   The cooling device preferentially draws heat from the edge of the glass ribbon below the bottom so that the temperature of the edge of the glass ribbon decreases at a faster rate than the temperature inside the glass ribbon. 9. The apparatus according to claim 7, wherein the apparatus is configured as follows.   The cooling device takes more heat from the edge of the glass ribbon below the bottom than the heat given by the heating device to the contact surface of the molten glass in contact with the edge guiding member. 10. The device according to claim 7, wherein the device is configured.

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