Patent Publication Number: US-2020299174-A1

Title: Float glass manufacturing apparatus

Description:
TECHNICAL FIELD 
     Exemplary embodiments of the present invention relate to a float glass manufacturing apparatus, and particularly, to a float glass manufacturing apparatus having a cooling module capable of cooling a glass ribbon formed during a process of manufacturing plate glass by a float method. 
     BACKGROUND ART 
     In general, a plate glass manufacturing apparatus using a float method forms a glass ribbon by continuously supplying molten glass and allowing the molten glass to flow on molten metal accommodated in a float bath. The formed glass ribbon is supplied into and annealed in an annealing lehr disposed adjacent to an outlet of the float bath. The glass ribbon is discharged to the outside of the annealing lehr and then cooled so that a temperature thereof nearly reaches a room temperature. Thereafter, the glass ribbon is cut to have a predetermined dimension and thus manufactured as plate glass. 
     Meanwhile, during the process in which the glass ribbon is formed as the molten glass is supplied into the float bath and flows so that a width thereof is increased, a temperature of a central portion, which is formed at a center of an overall width of the glass ribbon, is higher than a temperature of an outer portion close to a width end of the glass ribbon because of the nature of the molten glass such as viscosity of the molten glass that affects a flow of the molten glass. This difference in temperature affects a flow of the glass ribbon, which makes it difficult to manufacture the plate glass with high quality. 
     Further, the glass ribbon can need to be cooled during the process of forming the glass ribbon. In general, a method of allowing the glass ribbon to exchange heat with a water-cooled cooler, which is disposed above the glass ribbon and extends in a width direction of the glass ribbon, can be considered as a principal method of cooling the glass ribbon. 
     However, in the case in which the water-cooled cooler, which extends in the width direction of the glass ribbon, is used for the process of producing plate glass having a large width, the cooler sags due to a load of a central portion of the cooler. For this reason, there can be a problem in that a liquid surface of the glass ribbon can be inadvertently formed, and volatile substances existing at the periphery of the float bath are condensed on a surface of the cooler and fall onto the liquid surface of the glass ribbon, which can cause defects. 
     The above-mentioned background art is technical information thought out to make the invention or learned in the course of making the invention by the inventor, and cannot be thus said to be technical information known to the public before filing the invention. 
     DISCLOSURE 
     Technical Problem 
     Exemplary embodiments of the present invention provide a float glass manufacturing apparatus having a cooling module which supplies a cooling gas capable of cooling a glass ribbon while making a temperature uniform over an overall width of the glass ribbon in order to manufacture plate glass with high quality. 
     Technical Solution 
     A float glass manufacturing apparatus according to a first exemplary embodiment of the present invention includes a float bath which accommodates molten metal and allows a glass ribbon to flow on a liquid surface of the molten metal in a first direction; a ceiling unit which is disposed to be spaced upward apart from the float bath and elongated in the first direction; and a cooling module which is disposed in at least a part of an entire region of the ceiling unit in the first direction and supplies downward a cooling gas that cools the glass ribbon. 
     In the present exemplary embodiment, the cooling module can supply the cooling gas at least to a central portion based on an overall width of the glass ribbon in a second direction that intersects the first direction. 
     In the present exemplary embodiment, a cooling rate, which indicates a degree to which the glass ribbon is cooled by the cooling module, can vary over the overall width of the glass ribbon. 
     In the present exemplary embodiment, the cooling rate can be lower at an outer portion outside the central portion than at the central portion based on the overall width of the glass ribbon. 
     In the present exemplary embodiment, a discharge flow rate at which the cooling gas supplied by the cooling module is discharged can vary over the overall width of the glass ribbon. 
     In the present exemplary embodiment, the discharge flow rate of the cooling gas can be lower at an outer portion outside the central portion than at the central portion based on the overall width of the glass ribbon. 
     In the present exemplary embodiment, the float glass manufacturing apparatus can include a heating module which has a heating unit positioned between the float bath and the ceiling unit to heat the glass ribbon. 
     In the present exemplary embodiment, the heating unit and the cooling module can be disposed to be spaced apart from each other in the first direction. 
     In the present exemplary embodiment, a first spacing distance, which is a distance between the float bath and a discharge position at which the cooling gas supplied by the cooling module is discharged, can be equal to or smaller than a second spacing distance which is a distance between the heating unit and the float bath. 
     In the present exemplary embodiment, the cooling module can be disposed in a region corresponding to a section in which a width of the glass ribbon is decreased in an entire region of the ceiling unit in the first direction. 
     In the present exemplary embodiment, the cooling module can have multiple discharge tubes provided in a second direction to discharge the cooling gas. 
     In the present exemplary embodiment, the float glass manufacturing apparatus can include a sensor unit which detects a change in temperature of the glass ribbon between an upstream point positioned upstream from the cooling module in the first direction and a downstream point positioned downstream from the cooling module. 
     In the present exemplary embodiment, the cooling module can include a chamber which is disposed above the ceiling unit and accommodates the cooling gas supplied from the outside, and a discharge tube which is disposed to vertically penetrate the ceiling unit and discharges downward the cooling gas accommodated in the chamber. 
     In a second exemplary embodiment of the present invention, a degree, to which a discharge position at which the cooling gas supplied by the cooling module is discharged is spaced upward apart from the float bath, can vary over the overall width of the glass ribbon. 
     In the present exemplary embodiment, the degree to which the discharge position of the cooling gas is spaced upward apart from the float bath can be larger at an outer portion outside the central portion than at the central portion based on the overall width of the glass ribbon. 
     In a third exemplary embodiment of the present invention, the chamber can be partitioned, by a partition wall, into multiple unit chambers disposed in the second direction that intersects the first direction of the glass ribbon. 
     Advantageous Effects 
     The float glass manufacturing apparatus according to the exemplary embodiments of the present invention has the cooling module which supplies a cooling gas capable of cooling the glass ribbon while making a temperature uniform over an overall width of the glass ribbon, and as a result, it is possible to make a flow of the glass ribbon uniform and thus to manufacture plate glass with optically high quality. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a side view schematically illustrating a float glass manufacturing apparatus according to exemplary embodiments of the present invention when viewed from the lateral side. 
         FIG. 2  is a top plan view schematically illustrating a float bath illustrated in  FIG. 1  when viewed from above to below. 
         FIG. 3  is a front view schematically illustrating a float glass manufacturing apparatus according to a first exemplary embodiment of the present invention when viewed from the front side. 
         FIG. 4  is a front view schematically illustrating a modified example of the float glass manufacturing apparatus according to the first exemplary embodiment of the present invention when viewed from the front side. 
         FIG. 5  is a front view schematically illustrating a float glass manufacturing apparatus according to a second exemplary embodiment of the present invention when viewed from the front side. 
         FIG. 6  is a front view schematically illustrating a float glass manufacturing apparatus according to a third exemplary embodiment of the present invention when viewed from the front side. 
     
    
    
     EXPLANATION OF REFERENCE NUMERALS AND SYMBOLS 
     
         
         
           
               1000 : Float glass manufacturing apparatus  1100 : Float 
             bath 
               1110 : Roller  1200 : Ceiling unit 
               1210 : Cooling module  1211 : Discharge position 
               1212 : Chamber  1213 : Discharge tube 
               1214 : Partition wall  1220 : Heating module 
               1221 : Heating unit  1230 : Sensor unit 
               1240 : Brick unit  1250 : Gas supply channel 
             M: Central portion d 1 : First direction 
             d 2 : Second direction h 1 : First spacing distance 
             h 2 : Second spacing distance 
           
         
       
    
     [Mode for Invention] 
     The present invention will be apparent with reference to exemplary embodiments to be described below in detail together with the accompanying drawings. However, the present invention is not limited to the exemplary embodiments disclosed herein but will be implemented in various forms. The exemplary embodiments are provided so that the present invention is completely disclosed, and a person with ordinary skill in the art can fully understand the scope of the present invention. Therefore, the present invention will be defined only by the scope of the appended claims. Meanwhile, the terms used in the present specification are for explaining the exemplary embodiments, not for limiting the present invention. Unless particularly stated otherwise in the present specification, a singular form also includes a plural form. In addition, the terms such as “comprises (includes)” and/or “comprising (including)” used in the specification do not exclude presence or addition of one or more other constituent elements, steps, operations, and/or elements, in addition to the mentioned constituent elements, steps, operations, and/or elements. The terms such as “first” and “second” can be used to describe various constituent elements, but the constituent elements should not be limited by the terms. These terms are used only to distinguish one constituent element from another constituent element. 
     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a side view schematically illustrating a float glass manufacturing apparatus according to exemplary embodiments of the present invention when viewed from the lateral side.  FIG. 2  is a top plan view schematically illustrating a float bath illustrated in  FIG. 1  when viewed from above to below.  FIG. 3  is a front view schematically illustrating a float glass manufacturing apparatus according to a first exemplary embodiment of the present invention when viewed from the front side. 
     Referring to  FIGS. 1 to 3 , the first exemplary embodiment of the present invention relates to a float glass manufacturing apparatus  1000 , and particularly, to the float glass manufacturing apparatus  1000  which has a cooling module  1210  capable of cooling a glass ribbon while reducing a difference in temperature of the glass ribbon that is not uniform in a width direction of the glass ribbon when forming the glass ribbon during a process of manufacturing plate glass by using a float method. 
     The float glass manufacturing apparatus  1000  according to the first exemplary embodiment of the present invention can include a float bath  1100 , a ceiling unit  1200 , a cooling module  1210 , and a heating module  1220 . 
     The float bath  1110  can be a receiving furnace shaped to be opened at an upper side thereof so as to receive molten metal. Here, the molten metal can include, for example, molten tin or a molten tin alloy and can have larger specific gravity than molten glass. The molten metal can be maintained at a high temperature (about 600° C. to about 1,100° C.). The float bath  1100  can include therein a refractory material in order to accommodate the high-temperature molten metal. The float bath  1100  can include an inlet through which the molten glass is supplied, and an outlet through which the molten glass flows and is formed and discharged as the glass ribbon. As the molten glass flows on a liquid surface of the molten metal in a first direction d 1  from the inlet toward the outlet of the float bath  1100 , the glass ribbon can be formed in the form of a ribbon elongated in the first direction d 1 . 
     The ceiling unit  1200  is disposed to be spaced upward apart from the float bath  1100  and elongated in the first direction d 1 . The ceiling unit  1200  is positioned above the float bath  1110  and can isolate the float bath  1110  from the outside. The ceiling unit  1200  can be formed such that brick units  1240  each having a predetermined thickness are arranged in the first direction d 1 . Since the ceiling unit  1200  is disposed above the float bath  1100  and the float bath  1100  is disposed below the ceiling unit  1200 , a float chamber  1300 , which is a space between the ceiling unit  1200  and the float bath  1100 , can be formed. Each of the brick units  1240 , which constitute the ceiling unit  1200 , can be a refractory brick in order to accommodate high-temperature air in the float chamber  1300  which is heated by the high-temperature molten metal and the high-temperature molten glass. The refractory brick can endure a high temperature, and the refractory brick is not excessively softened or changed in volume at a high temperature. The refractory brick can have excellent corrosion resistance and abrasion resistance against gases or slag. The float chamber  1300  can be filled with a reducing gas including nitrogen N 2  and hydrogen H 2  in order to prevent oxidation of the molten metal and to prevent a chemical reaction between the molten metal and fine substances produced by volatilization of the molten glass. The ceiling unit  1200  can include gas supply channels  1250  through which the reducing gas can be supplied. Each of the gas supply channels  1250  can be a space between the brick units  1240  or a tubular member disposed in the space between the brick units  1240 . The reducing gas can be supplied into the float chamber  1300  from an upper space of the ceiling unit  1200  through the gas supply channels  1250  formed in the ceiling unit  1200 . In addition, a gas pressure in the float chamber  1300  can be set to be higher than the atmospheric pressure in order to prevent an inflow of air from the outside. 
     The cooling module  1210  can be disposed in at least a part of the entire region of the ceiling unit  1200  in the first direction d 1  and can supply downward a cooling gas capable of cooling the glass ribbon. 
     The cooling gas can be a low-temperature reducing gas including nitrogen N 2  and hydrogen H 2  in order to prevent oxidation of the molten metal and to prevent a chemical reaction between the molten metal and the fine substances produced by volatilization of the molten glass. For example, the low-temperature reducing gas can have a temperature of about 30° C. and can be supplied into the upper space of the ceiling unit  1200 . When the reducing gas is accommodated in the upper space of the ceiling unit  1200 , a temperature of the reducing gas can be raised to a temperature of about 100° C. or more to about 150° C. or less by heat transferred from the float chamber  1300 . 
     The cooling module  1210  can be disposed in a second direction d 2  that intersects the first direction d 1  which is a flow direction of the glass ribbon. The second direction d 2  can be a width direction of the glass ribbon. The cooling module  1210  can include a discharge tube  1213  through which the cooling gas is discharged. The discharge tube  1213  can vertically penetrate a discharge tube block disposed in the form of a block that protrudes downward from the ceiling unit  1200 , such that the discharge tube  1213  can have a space in which a fluid can flow. The cooling gas can be discharged through the discharge tube  1213 . The discharge tube  1213  can extend in the second direction d 2  so that the cooling gas is supplied over a predetermined length region in the width direction of the glass ribbon. The cooling gas can be supplied over an overall width of the glass ribbon. Here, the overall width of the glass ribbon is a predetermined width in the first direction d 1  which is the flow direction of the glass ribbon. The overall width of the glass ribbon can define an imaginary region formed from one end to the other end that define the width of the glass ribbon. The multiple discharge tubes  1213  can be provided in the second direction d 2  of the glass ribbon. The multiple discharge tubes  1213  can be disposed at a constant interval in the second direction d 2  in order to supply the cooling gas over the overall width of the glass ribbon. 
     The cooling module  1210  can include a chamber  1212  that accommodates the cooling gas. The chamber  1212  can be disposed above the ceiling unit  1200  and have a space capable of accommodating the cooling gas supplied from the outside. The chamber  1212  can include a communication port that can communicate with the discharge tube  1213  which is disposed to vertically penetrate the ceiling unit  1200 . The cooling gas accommodated in the chamber  1212  can be discharged to the communication port and supplied downward by being guided along the discharge tube  1213 . The chamber  1212  can extend in the second direction d 2 . 
     Meanwhile, a temperature of the glass ribbon can decrease toward outer portions, which become close to ends in the width direction that defines the width of the glass ribbon, from a central portion M positioned at a relative center of the overall width of the glass ribbon which is defined in the second direction d 2  which is the width direction of the glass ribbon. The reason is as follows. The inlet through which the molten glass is introduced is formed at one end of the float bath  1100  which is positioned at a center based on the width of the float bath  1100 . A width of the inlet can be smaller than the width of the float bath  1100 . When the molten glass is introduced from the inlet, the molten glass is introduced in the first direction d 1  while being concentrated in the central region based on the width of the float bath  1100 , such that the glass ribbon is formed. Therefore, even though the width of the introduced molten glass increases, the molten glass flows while being concentrated on the central portion M due to the nature of the molten glass, such as viscosity, that affects a flow of the molten glass. As a result, it is more difficult to disperse heat at the central portion M than at the outer portions of the glass ribbon. This difference in temperature affects a flow of the glass ribbon, and as a result, there can be a problem in that when a flow velocity of the glass ribbon varies, a thickness of the glass ribbon becomes non-uniform, and glass particles are non-uniformly distributed. 
     Therefore, to cool the glass ribbon while making the temperature of the glass ribbon uniform over the overall width of the glass ribbon, the cooling module  1210  can supply the cooling gas to at least the central portion M based on the overall width in the second direction d 2  that intersects the first direction d 1  of the glass ribbon. When the cooling gas is supplied to at least the central portion M based on the overall width of the glass ribbon, a flow rate of the low-temperature cooling gas becomes relatively higher at the central portion M than at the outer portions close to the ends in the width direction of the glass ribbon. Further, the cooling gas and the glass ribbon exchange heat with each other more smoothly at the central portion M than at the outer portions. As a result, the temperature can decrease more greatly at the central portion M than at the outer portions. Therefore, the temperature can become uniform at the central portion M having a relatively high temperature and the outer portions having a relatively low temperature. 
     A cooling rate, which indicates a degree to which the glass ribbon is cooled by the cooling module  1210 , can vary over the overall width of the glass ribbon. Specifically, the cooling rate can be lower at the outer portions outside the central portion M than at the central portion M in the overall width region of the glass ribbon. Here, the cooling rate can mean the amount of heat dissipated from a unit surface area of the glass ribbon per unit time or can mean the amount of decrease in temperature in the unit surface area of the glass ribbon per unit time. Since the cooling rate is lower at the outer portions than at the central portion M based on the overall width of the glass ribbon, the temperature can be uniform over the overall width region of the glass ribbon. 
     In the case in which a difference in cooling rate of the glass ribbon is made by adjusting a flow rate of the cooling gas being discharged from the discharge tube  1213 , a discharge flow rate of the cooling gas supplied and discharged from the cooling module  1210  can vary over the overall width of the glass ribbon. Specifically, the discharge flow rate of the cooling gas can be lower at the outer portions outside the central portion M than at the central portion M based on the overall width region of the glass ribbon. The discharge flow rate can be adjusted by varying a lateral cross-sectional area a 1  of the discharge tube  1213 . Here, the cross-sectional area a 1  can be an area of a cross section formed by cutting the discharge tube  1213  with an imaginary plane approximately parallel to the liquid surface of the glass ribbon. Specifically, the discharge flow rate can be adjusted such that the cross-sectional area a 1  of the discharge tube  1213  through which the cooling gas is discharged toward the position of the central portion M of the glass ribbon is larger than the cross-sectional area a 1  of the discharge tube  1213  through which the cooling gas is discharged toward the positions of the outer portions, in order to supply a larger amount of cooling gas to the central portion M. In addition, the discharge flow rate can be adjusted by varying a position at which the cooling gas is supplied in the chamber  1212  extending in the second direction d 2 . Specifically, when the cooling gas is extensively supplied to the central portion M of the chamber  1212 , the cooling gas flow rate can be relatively high at the central portion M even though the cooling gas flows and diffuses toward the outer portions of the chamber  1212 . Therefore, the discharge tube  1213  disposed at the position corresponding to the central portion M of the chamber  1212  can supply the cooling gas to the glass ribbon at a higher flow rate than the discharge tube  1213  disposed at the position corresponding to the outer portion of the chamber  1212 . 
     In the entire region of the ceiling unit  1200  in the first direction d 1 , the cooling module  1210  can be disposed in a region corresponding to a section in which the width of the glass ribbon is decreased. The float glass manufacturing apparatus  1000  can include rollers  1110  disposed at both ends based on the width of the glass ribbon. The rollers  1110  can be disposed at a downstream side in the first direction d 1  from the inlet of the float bath  1100  through which the molten glass is supplied. The multiple rollers  1110  can be disposed in the first direction d 1  at both ends based on the width of the glass ribbon. As the rollers  1110  rotate in a state in which the rollers  1110  are in contact with the glass ribbon, the width and the thickness of the glass ribbon can be determined. For example, the rollers  1110  are disposed at a predetermined angle θ 1  with respect to a line c parallel to the first direction d 1  which is the flow direction of the glass ribbon, and the predetermined angle θ 1  is formed in a direction toward lateral sides of the float bath  1100 . Therefore, the width of the glass ribbon can be increased as the rollers  1110  rotate, and the thickness of the glass ribbon can be decreased as a rotational speed of the rollers  1110  is increased. The width of the glass ribbon, which is increased due to viscosity of the glass ribbon, can be gradually decreased after the glass ribbon passes through the section in which the rollers  1110  are disposed to increase the width of the glass ribbon in the second direction d 2  which is the width direction. The cooling module  1210  is disposed in a corresponding region of the ceiling unit  1200  positioned above a section a 2  in which the width of the glass ribbon is decreased, such that it is possible to more efficiently cool and form the glass ribbon. The section in which the rollers  1110  are disposed and a section upstream from the section in which the rollers  1110  are disposed can be a section in which the thickness of the glass ribbon is determined. If the cooling module  1210  is disposed in a corresponding region of the ceiling unit  1200  above this section and cools the glass ribbon, efficiency and process stability can deteriorate because the glass ribbon is heated and cooled at the same time. In addition, considering that a gas discharge position  1211  of the cooling module  1210  is close to the glass ribbon, it can be difficult to ensure an installation space for the rollers  1110 . Therefore, to cool the glass ribbon, the cooling module  1210  can be disposed in the corresponding region of the ceiling unit  1200  positioned above the section a 2  in which the width of the glass ribbon is decreased. According to a modified exemplary embodiment, the cooling module  1210  can be disposed in a region of the ceiling unit  1200  which is formed at an upper end of the central portion M of the glass ribbon that flows in a zone within about 3 m upstream from the roller  1110  disposed at the most downstream side among the rollers  1110 . Therefore, the central portion M of the glass ribbon is cooled before the outer portions of the glass ribbon are cooled, and as a result, it is possible to decrease a difference in temperature in the width direction of the glass ribbon. 
     The heating module  1220  can heat the glass ribbon in order to induce annealing of the glass ribbon and to prevent solidification of the glass ribbon which occurs as the glass ribbon is cooled. The multiple heating modules  1220  can be disposed in the first direction d 1  in the ceiling unit  1200 . The heating module  1220  can include a heating unit  1221 . The heating unit  1221  can be positioned between the float bath  1100  and the ceiling unit  1200  and can supply heat to the glass ribbon. The heating unit  1221  can be a heat generating member, and the multiple heating units  1221  can be provided. For example, the heating unit  1221  can have therein a coil capable of generating heat, and heat can be generated as an electric current is supplied to the coil. The heating units  1221  can be disposed in the second direction d 2  and can supply heat over the overall width of the glass ribbon. The temperatures of the multiple heating units  1221  can be controlled so that the temperature can be uniform over the overall width of the glass ribbon. 
     The heating module  1220  including the heating units  1221  can be disposed to be spaced apart from the cooling module  1210  in the first direction d 1 . The order in which the cooling module  1210  and the heating unit  1221  are disposed in the first direction d 1  can be designed in various ways in consideration of an optimum process for the glass ribbon.  FIG. 1  illustrates one example in which the multiple heating units  1221  are disposed in the first direction d 1  and the cooling modules  1210  are disposed between the zones in which the multiple heating units  1221  are disposed in the first direction d 1 . 
     If the heating unit  1221  is disposed to be closer to the glass ribbon from the ceiling unit  1200  than is the discharge position  1211  in the case in which the discharge position  1211  at which the cooling gas is discharged and the heating unit  1221  are disposed adjacent to each other in the first direction d 1 , cooling efficiency can deteriorate because the cooling gas can be heated by the heating unit  1221  while the cooling gas is discharged. To solve the problem, a first spacing distance h 1 , which is a distance between the float bath  1100  and the discharge position  1211  at which the cooling gas supplied by the cooling module  1210  is discharged, can be equal to a second spacing distance h 2  which is a distance between the heating unit  1221  and the float bath  1100 . The discharge position  1211  can be a position at which the discharged gas exits the discharge tube  1213 , and the discharge position  1211  can be a lower end of the discharge tube  1213 . The first spacing distance h 1  can be a distance between the discharge position  1211  and the liquid surface of the glass ribbon that flows on the molten metal accommodated in the float bath  1100 . The second spacing distance h 2  can be a distance between the lower end of the heating unit  1221  and the liquid surface of the glass ribbon that flows on the molten metal accommodated in the float bath  1100 . In the case in which the first spacing distance h 1  is equal to the second spacing distance h 2 , the cooling gas discharged from the discharge tube  1213  may not be affected by the heating unit  1221 , and the temperature of the cooling gas may not be increased. 
       FIG. 4  is a front view schematically illustrating a modified example of the float glass manufacturing apparatus according to the first exemplary embodiment of the present invention when viewed from the front side. 
     Referring to  FIG. 4 , the first spacing distance h 1  can be smaller than the second spacing distance h 2 . In the case in which the first spacing distance h 1  is smaller than the second spacing distance h 2 , the cooling gas discharged from the discharge tube  1213  may not be affected by the heating unit  1221 , and the temperature of the cooling gas may not be increased. In addition, it is possible to improve cooling efficiency because the cooling gas can be supplied at the position closer to the glass ribbon in comparison with the case in which the first spacing distance h 1  and the second spacing distance h 2  are equal to each other. 
     The float glass manufacturing apparatus  1000  can further include sensor units  1230 . 
     The sensor units  1230  can detect a change in temperature of the glass ribbon between an upstream point, which is positioned upstream from the cooling module  1210  in the first direction d 1 , and a downstream point positioned downstream from the cooling module  1210 . The sensor unit  1230  can be disposed in an upper space of the ceiling unit  1200 , and a radiation pyrometer for detecting heat can be used as the sensor unit  1230 . The float glass manufacturing apparatus  1000  can adjust a flow rate of the cooling gas to be supplied into the chamber  1212  based on an aspect related to a change in temperature which is detected by the sensor unit  1230  and occurs in the width direction and the flow direction of the glass ribbon. That is, the float glass manufacturing apparatus  1000  can adjust a flow rate of the cooling gas to be supplied to the glass ribbon so that an optimum condition for making a temperature distribution uniform in the width direction of the glass ribbon is achieved. 
       FIG. 5  is a front view schematically illustrating a float glass manufacturing apparatus according to a second exemplary embodiment of the present invention when viewed from the front side. 
     Referring to  FIG. 5 , the float glass manufacturing apparatus  1000  according to the second exemplary embodiment of the present invention is configured such that there is a section in which a height of the discharge position  1211  at which the cooling gas is discharged varies in the width direction of the glass ribbon. As a result, there can be a difference in cooling rate between the central portion M, which is positioned at a relative center based on the overall width of the glass ribbon, and the outer portions outside the central portion M. That is, a degree to which the discharge position  1211  at which the cooling gas supplied by the cooling module  1210  is discharged is spaced upward apart from the float bath  1100  can vary in the overall width of the glass ribbon. Specifically, regarding the degree to which the discharge position  1211  of the cooling gas is spaced upward apart from the float bath  1100 , a distance h 4  between the liquid surface of the glass ribbon and a discharge position  1211   b  at the outer portion outside the central portion M can be larger than a distance h 3  between the liquid surface of the glass ribbon and a discharge position  1211   a  at the central portion M based on the overall width of the glass ribbon. In this case, the cooling gas is supplied to the outer portion of the glass ribbon from a higher position based on the liquid surface of the glass ribbon than the cooling gas being supplied to the central portion M. Therefore, the cooling gas more smoothly diffuses toward the periphery without being concentrated on the outer portion, such that the cooling rate can be lower at the outer portion than at the central portion M of the glass ribbon. 
       FIG. 6  is a front view schematically illustrating a float glass manufacturing apparatus according to a third exemplary embodiment of the present invention when viewed from the front side. 
     Referring to  FIG. 6 , the chamber  1212  of the float glass manufacturing apparatus  1000  according to the third exemplary embodiment of the present invention can be partitioned, by partition walls  1214 , into multiple unit chambers  1212   a  in the second direction d 2  that intersects the first direction d 1  of the glass ribbon. The partition wall  1214  can be a member that can partition the chamber into spaces and block a flow of the gas between the partitioned spaces. A flow of the gas can be blocked between the unit chambers  1212   a . In addition, the discharge tubes  1213  can be provided such that the number of and the positions of the discharge tubes  1213  correspond to the number of and the positions of the unit chambers  1212   a . The temperature of the cooling gas being supplied into the unit chambers  1212   a  can vary according to the unit chambers  1212   a . The cooling gas can be supplied, at different temperatures, to the glass ribbon through the discharge tubes  1213  formed to correspond to the unit chambers  1212   a . Specifically, the cooling gas having a relatively low temperature is supplied into the unit chamber  1212   a  disposed above the ceiling unit  1200  corresponding to the central portion M based on the overall width of the glass ribbon, and the cooling gas having a relatively high temperature is supplied into the unit chamber  1212   a  disposed above the ceiling unit  1200  corresponding to the outer portion of the glass ribbon, such that the temperature of the cooling gas to be supplied to the central portion M can be relatively lower than the temperature of the cooling gas to be supplied to the outer portion of the glass ribbon. Therefore, the cooling rate can be lower at the outer portion than at the central portion M of the glass ribbon, and the temperature can be uniform over the overall width of the glass ribbon. Particularly, the cooling gas having a temperature of about 200° C. to about 300° C. is supplied to the central portion M of the glass ribbon, and the cooling gas having a temperature of about 600° C. to about 700° C. is supplied to the outer portion of the glass ribbon, such that the temperature can be uniform over the overall width of the glass ribbon. 
     An example of an operation of the float glass manufacturing apparatus  1000  according to the exemplary embodiment of the present invention will be described below. 
     The molten glass can be introduced into the inlet of the float bath  1100  and can flow on the upper surface of the molten metal accommodated in the float bath  1100  while forming the glass ribbon in the first direction d 1 . The width and the thickness of the glass ribbon can be determined by the multiple rollers  1110  disposed at both ends of the glass ribbon based on the width direction of the glass ribbon. The heating units  1221  can be disposed in the ceiling unit  1200  in the first direction d 1  of the glass ribbon and can adjust the temperature of the glass ribbon so that the glass ribbon can be slowly cooled while flowing. The width of the glass ribbon can be decreased while the glass ribbon passes through the zone in which the rollers  1110  are disposed. The glass ribbon can be cooled by the cooling module  1210  disposed above the region in which the width of the glass ribbon is decreased. In this case, it is possible to obtain an entirely uniform temperature by making the cooling rate different between the central portion M and the outer portion based on the overall width of the glass ribbon. The glass ribbon can be slowly cooled while consistently flowing and formed to have a targeted width and a targeted thickness, and then the glass ribbon can be discharged through the outlet of the float bath  1100 . 
     Effects of the float glass manufacturing apparatus  1000  according to the exemplary embodiment of the present invention will be described below. 
     The float glass manufacturing apparatus  1000  according to the exemplary embodiments of the present invention has the cooling module  1210  which supplies the cooling gas capable of cooling the glass ribbon while making a temperature uniform over an overall width of the glass ribbon, and as a result, it is possible to make a flow of the glass ribbon uniform and thus to manufacture plate glass with optically high quality. 
     According to the float glass manufacturing apparatus  1000  according to the exemplary embodiments of the present invention, the first spacing distance h 1 , which is the distance between the float bath  1100  and the discharge position  1211  through which the cooling gas supplied by the cooling module  1210  is discharged, can be equal to or smaller than the second spacing distance h 2  which is the distance between the heating unit  1221  and the float bath  1100 , and as a result, it is possible to prevent a deterioration in cooling efficiency caused by the influence of the heating unit  1221  on the cooling gas. 
     The float glass manufacturing apparatus  1000  according to the exemplary embodiments of the present invention has the heating module  1220  including the heating units  1221 , and as a result, it is possible to prevent the solidification of the glass ribbon and to induce annealing of the glass ribbon by adjusting the temperature of the glass ribbon. 
     The float glass manufacturing apparatus  1000  according to the exemplary embodiments of the present invention includes the sensor unit  1230 , and as a result, it is possible to adjust a flow rate of the cooling gas to be supplied into the chamber  1212  by detecting a change in temperature of the glass ribbon and thus to adjust the temperature of the glass ribbon by adjusting the flow rate of the cooling gas to be supplied to the glass ribbon. 
     The float glass manufacturing apparatus  1000  according to the first exemplary embodiment of the present invention can adjust the temperature of the glass ribbon by adjusting the flow rate of the cooling gas to be supplied to the glass ribbon and can reduce a difference in temperature over the overall width of the glass ribbon. 
     The float glass manufacturing apparatus  1000  according to the second exemplary embodiment of the present invention can adjust the temperature of the glass ribbon by adjusting the flow rate of the cooling gas to be supplied to the glass ribbon by varying the height of the discharge position  1211  at which the cooling gas is discharged, and can reduce a difference in temperature over the overall width of the glass ribbon. 
     The float glass manufacturing apparatus  1000  according to the third exemplary embodiment of the present invention includes the unit chambers  1212   a  formed by partitioning the chamber that accommodates the cooling gas, and as a result, it is possible to adjust the temperature of the glass ribbon by adjusting the temperature of the cooling gas accommodated in the unit chambers  1212   a  or adjusting the amount of cooling gas accommodated in the unit chambers  1212   a , and it is possible to reduce a difference in temperature over the overall width of the glass ribbon. 
     While the present invention has been described with reference to the aforementioned exemplary embodiments, various modifications or alterations can be made without departing from the subject matter and the scope of the invention. Accordingly, the appended claims include the modifications or alterations as long as the modifications or alterations fall within the subject matter of the present invention.