Patent Publication Number: US-2021163331-A1

Title: Plate glass production apparatus, and molding member for use in plate glass production apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This U.S. non-provisional application is a continuation application of and claims the benefit of priority under 35 U.S.C. § 365(c) from PCT International Application PCT/JP2019/028857 filed on Jul. 23, 2019, which is designated the U.S., and is based upon and claims the benefit of priority of Japanese Patent Application No. 2018-152489 filed on Aug. 13, 2018, the entire contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a plate glass production apparatus and a molding member used in the plate glass production apparatus. 
     BACKGROUND ART 
     As a type of continuous production method of plate glass, the so-called fusion process has been known (e.g., Japanese Laid-Open Patent Application No. 2016-028005). 
     In this method, molten glass obtained by melting raw materials for glass is supplied to an upper end of a member for molding (hereafter, referred to as a “molding member”). The molding member is virtually wedge-shaped and pointed downward in cross section, and the molten glass flows down along two facing side surfaces of this molding member. The molten glass flowing down along both side surfaces is joined and integrated at a lower-side edge portion of the molding member (also referred to as the “confluence point”) to form a glass ribbon. Thereafter, the glass ribbon is drawn downward by traction members such as rollers while being slowly cooled down, and cut to have predetermined dimensions. 
     In the fusion process, the molding member has an elongated shape in which the side surfaces and the confluence point extend along the horizontal axis. Also, the dimension in this horizontal axis direction (hereafter, referred to as the “longitudinal direction”) corresponds to the width direction of the plate glass; therefore, in the case where the width of the plate glass to be produced needs to be increased, the dimension needs to be set long enough. 
     Due to such constraints on the configuration and the use environment, if using the molding member for a long time, problems may arise such that the molding member is deformed by high temperature creep, and bends in the direction of gravity. Also, if such deformation occurs in the molding member, it causes problems in that the dimensional precision of the produced plate glass is reduced, and in particular, the thickness becomes uneven. 
     Therefore, molding members used in continuous production apparatuses of plate glass, with which such creep problems can be alleviated, are desired even now. 
     SUMMARY 
     According to the present disclosure, a production apparatus that continuously produces plate glass is provided that includes a molding member configured to mold molten glass to form a glass ribbon, wherein the molding member is (i) constituted with graphite or includes a portion constituted with graphite, and/or (ii) supported by a support member containing graphite, wherein in a case of (i), the molding member is surrounded by a fence, and in a case of (ii), the support member is surrounded by the fence together with the molding member, and wherein a space surrounded by the fence is adjusted to have an oxygen concentration of less than or equal to 100 ppm. 
     Also, according to the present disclosure, a molding member is provided for a production apparatus that continuously produces plate glass, wherein the molding member is (i) constituted with graphite or includes a portion constituted with graphite, and/or (ii) supported by a support member containing graphite, wherein in a case of (i), the molding member is surrounded by a fence, and in a case of (ii), the support member is surrounded by the fence together with the molding member, and wherein a space surrounded by the fence is adjusted to have an oxygen concentration of less than or equal to 100 ppm. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram illustrating an example of a configuration of a plate glass production apparatus according to an embodiment of the present disclosure; 
         FIG. 2  is an enlarged side view of a molding part in  FIG. 1 ; 
         FIG. 3  is a schematic diagram illustrating the cross section and peripheral members in a direction perpendicular to the longitudinal direction of the molding member illustrated in  FIG. 2 ; 
         FIG. 4  is a schematic diagram illustrating part of a configuration of another plate glass production apparatus according to an embodiment of the present disclosure; and 
         FIG. 5  is a schematic diagram illustrating part of a configuration of yet another plate glass production apparatus according to an embodiment of the present disclosure. 
     
    
    
     EMBODIMENTS OF THE INVENTION 
     In the following, embodiments according to the present disclosure will be described with reference to the drawings. 
     According to the present disclosure, a plate glass production apparatus can be provided, with which the creep problems are alleviated significantly. 
     Also, according to the present disclosure, a molding member for such a plate glass production apparatus can be provided. 
     (Plate Glass Production Apparatus According to an Embodiment of the Present Disclosure) 
     With reference to  FIGS. 1 to 3 , a plate glass production apparatus according to an embodiment of the present disclosure will be described. 
       FIG. 1  schematically illustrates a configuration of a plate glass production apparatus  100  according to an embodiment of the present disclosure (hereafter, referred to as the “first production apparatus”). The first production apparatus  100  can continuously produce plate glass by the fusion process. 
     As illustrated in  FIG. 1 , the first production apparatus  100  includes, from the upstream side, a melting part  110 , a molding part  130 , a slow cooling part  180 , and a cutting part  190 . 
     The melting part  110  is a place in the first production apparatus  100  that has a function of melting raw materials for glass, to form molten glass MG. The molding part  130  is a place that has a function of molding the molten glass MG supplied from the melting part  110 , to form a glass ribbon GR. The slow cooling part  180  is a place that has a function of slowly cooling down the glass ribbon GR formed in the molding part  130 . Also, the cutting part  190  is a place that has a function of cutting the slowly-cooled glass ribbon GR. 
     Note that in the first production apparatus  100  illustrated in  FIG. 1 , the boundaries between the parts are set for the sake of convenience, and not defined strictly. For example, a member such as a pipe or the like to supply the molten glass MG to the molding part  130  may be included in the melting part  110 , or may be included in the molding part  130 . 
     As illustrated in  FIG. 1 , the melting part  110  includes a melting furnace  112  in which the raw materials for glass is melted. The melting furnace  112  includes an outlet  114 , and from the outlet  114 , the molten glass MG is discharged. Note that although not illustrated in  FIG. 1 , the melting part  110  may further include a clearing part to remove air bubbles from the molten glass, and/or a mixing part to uniformly mix the molten glass. 
     The molten glass MG discharged from the outlet  114  of the melting furnace  112  is then introduced into the molding part  130  through an inlet  120 . The molding part  130  includes a molding member  132  that molds the glass ribbon GR from the molten glass MG by the fusion process. 
     Also, the molding part  130  may include rollers (not illustrated). 
     Note that the molding part  130  will be described in detail later. 
     The glass ribbon GR molded in the molding part  130  is then introduced into the slow cooling part  180 . One pair or two or more pairs of cooling rollers are arranged in the slow cooling part  180 . 
     For example, in the example illustrated in  FIG. 1 , the slow cooling part  180  includes two pairs of cooling rollers. The first pair of cooling rollers is constituted with two cooling rollers  182 , and the second pair of cooling rollers is constituted with two other cooling rollers  184 . By rotating the cooling rollers  182  and  184  in a state of having the glass ribbon GR sandwiched in-between, the glass ribbon GR is towed downward. Also, the cooling rollers  182  and  184  are controlled to have predetermined temperatures, respectively, so as to be capable of cooling the glass ribbon GR. 
     Thereafter, the sufficiently and slowly cooled glass ribbon GR is conveyed to the cutting part  190 . The cutting part  190  includes a cutting means  192 , such as a cutter, by which the glass ribbon GR is cut to have predetermined dimensions. 
     The first production apparatus  100  can continuously produce plate glass  194  through the above steps. 
       FIGS. 2 and 3  illustrate enlarged views of the molding part  130  of the first production apparatus  100 .  FIG. 2  schematically illustrates a side view of the molding member  132  while molding the glass ribbon GR as viewed from one side. Also,  FIG. 3  schematically illustrates a cross section perpendicular to the longitudinal direction (the X direction) of the molding member  132  illustrated in  FIG. 2 . Note that these figures also illustrate members and the like included in the surroundings of the molding member  132 . 
     As illustrated in  FIGS. 2 and 3 , the molding member  132  has virtually a wedge-like shape in cross section. 
     More specifically, the molding member  132  has a top surface  134 , and a first side surface  138   a  and a second side surface  138   b  that face each other. 
     A recess part  136  whose top side is open along the longitudinal direction (the X direction) is formed in the top surface  134 . The first side surface  138   a  includes a first upper side surface  140   a  and a first lower side surface  142   a.  Similarly, the second side surface  138   b  includes a second upper side surface  140   b  and a second lower side surface  142   b.  Both the first upper side surface  140   a  and the second upper side surface  140   b  extend virtually in the longitudinal axis direction (the X direction) and virtually in the vertical direction (the Z direction), and consequently, are arranged virtually parallel to the XZ plane. On the other hand, the first lower side surface  142   a  and the second lower side surface  142   b  are tilted with respect to the vertical direction (the Z direction), and are arranged so as to intersect each other at the lower-side edge portion (side)  144  of the molding member  132 . 
     The upper end of the first lower side surface  142   a  is connected to the lower end of the first upper side surface  140   a,  and the upper end of the second lower side surface  142   b  is connected to the lower end of the second upper side surface  140   b.    
     As illustrated in  FIG. 2 , the molding member  132  further includes a pair of cap members  146 . The cap members  146  are arranged in the vicinity of the respective ends of the molding member  132  in the longitudinal direction (the X direction). The cap member  146  is used for fitting the glass ribbon GR into a predetermined width, namely, used as a stopper to prevent the glass ribbon GR from spreading beyond the predetermined width. 
     Also, a fence  150  is provided around the molding member  132 , and the surroundings of the molding member  132  is covered by this fence. In other words, the fence  150  forms a space  152  around the molding member  132 . However, as is clear from  FIG. 3 , the fence  150  has a removed portion, through which the glass ribbon GR is discharged toward the slow cooling part  180 . Therefore, the glass ribbon GR formed in the molding part  130  can be moved to the slow cooling part  180  without interfered by the fence  150 . 
     Note that in  FIGS. 2 and 3 , for the sake of clarification, the fence  150  is presented in a state of having a surface removed that is on the foreground side with respect to the paper. 
     During operation of the first production apparatus  100 , the space  152  is controlled to have an oxygen concentration of less than or equal to 100 ppm. Also, in order to make this possible, a gas inlet  154  is provided at a predetermined position on the fence  150 . An open/close valve may be provided in the gas inlet  154 . Also, if necessary, the fence  150  may also be further provided with a gas outlet (not illustrated). 
     The oxygen concentration of the space  152  can be controlled within the predetermined range described earlier, by supplying gas having a predetermined composition from the gas inlet  154 , or exhausting the gas from the gas outlet. 
     Next, a process of forming the glass ribbon GR by the molding member  132  will be described. 
     First, the space  152  inside the fence  150  is controlled to have a predetermined oxygen concentration. The oxygen concentration is less than or equal to 100 ppm, and favorably less than or equal to 50 ppm. For example, the space  152  may be adjusted to have the predetermined oxygen concentration by supplying an inert gas or a reducing gas from the gas inlet  154  of the fence  150 . 
     Next, as described earlier, the molten glass MG is supplied to the molding part  130  through the inlet  120 . The supplied molten glass MG is introduced into the top surface  134  of the molding member  132 . 
     The top surface  134  has the recess part  136  formed as described earlier, in which the molten glass MG can be contained. However, when the molten glass MG is supplied in excess of the containable capacity of the recess part  136 , the excess molten glass MG overflows along the first side surface  138   a  and the second side surface  138   b  of the molding member  132 , and flows out downward. 
     Accordingly, a first molten glass portion  160   a  is formed on the first upper side surface  140   a  of the molding member  132 , and a second molten glass portion  160   b  is formed on the second upper side surface  140   b  of the molding member  132 . 
     Thereafter, the first molten glass portion  160   a  flows further downward along the first lower side surface  142   a  of the molding member  132 . Similarly, the second molten glass portion  160   b  flows further downward along the second lower side surface  142   b  of the molding member  132 . 
     As a result, the first molten glass portion  160   a  and the second molten glass portion  160   b  reach the lower-side edge portion  144 , at which these portions are integrated. Accordingly, the glass ribbon GR is formed. 
     Note that thereafter, as described earlier, the glass ribbon GR is further drawn out in the vertical direction, and supplied to the slow cooling part  180 . 
     Here, in a conventional plate glass production apparatus, if using the molding member for a long time, problems may arise such that the molding member is deformed by high temperature creep, and bends in the direction of gravity (the Z direction). When such a bend occurs in the molding member, the amount of molten glass MG flowing out of the top surface side of the molding member becomes non-uniform along the longitudinal direction (the X direction), and thereby, a problem may arise in that the dimensional precision of the plate glass to be produced, and in particular, the thickness precision is reduced. 
     However, in the first production apparatus  100 , the molding member  132  has a feature of being constituted with graphite. 
     Graphite has relatively good creep resistance at high temperatures exceeding 1000° C. Therefore, in the case of forming the molding member  132  with graphite, the conventional problem of deformation by creep can be suppressed significantly. 
     However, graphite tends to be oxidized in a high-temperature oxygen-containing environment, and once oxidized, the surface smoothness tends to decrease and the surface tends to degrade. Putting it the other way around, these properties have prevented graphite from being used in the molding member  132 . 
     However, in the molding part  130  in the first production apparatus  100 , the molding member  132  is covered with the fence  150 , and the interior space  152  is controlled to be a “low oxygen environment” with an oxygen concentration of less than or equal to 100 ppm. Therefore, in the first production apparatus  100 , even when graphite is used for the molding member  132 , the molding member  132  can be prevented from degrading due to oxidation. 
     As a result, in the first production apparatus  100 , creep is unlikely to occur in the molding member  132 , and deformation and bends of the molding member  132  can be suppressed significantly. 
     Also, accordingly, even after the first production apparatus  100  would have been used for a long period of time, the dimensions of produced plate glass can be maintained with high precision. 
     Further, graphite has a heat resistance temperature of higher than or equal to 2000° C., and thus, has a good heat resistance. Further, graphite is strong against thermal shock, and has a feature of hardly breaking even if the temperature of the molding member  132  changes steeply. Further, graphite is easy to process, and has a feature that a smooth plane can be obtained relatively easily. 
     Such features allow the molding member  132  constituted with graphite to be used stably for a long time, even at high temperatures such as, for example, 1200° C. 
     As the member constituted with graphite according to the present disclosure, a material obtained from raw materials for graphite by cold isostatic press molding, extrusion molding, or press molding; a carbon-carbon composite obtained by calcining and carbonizing a composite material of graphite fiber and resin; and the like may be enumerated. 
     Note that it is undesirable for some types of glass to come into contact with graphite. In such a case, portions of the molding member  132  that come contact with the molten glass MG (including the first molten glass portion  160   a  and the second molten glass portion  160   b ) and/or the glass ribbon GR may be covered or coated with a material that does not react with the glass. 
     Here, the molding member  132  does not need to be constituted with graphite entirely. In other words, part of the molding member  132  may be constituted with graphite. In other words, graphite may be used in a way such that the creep resistance characteristic of the molding member  132  is improved. For example, graphite may be applied at a position where the creep resistance characteristic of the molding member  132  is likely to be improved, and/or in a shape with which the creep resistance characteristic of the molding member  132  is likely to be improved. 
     In this case, in general, the volume ratio of graphite to the entire molding member  132  is greater than or equal to 50%, favorably greater than or equal to 60%, more favorably greater than or equal to 70%, and even more favorably greater than or equal to 80%. 
     For example, graphite may be applied to the molding member  132  as a core bar extending along the longitudinal direction (the X direction) from one end (or its vicinity) to the other end (or its vicinity) in the molding member  132 . 
     Such a graphite core bar may satisfy D c /H=0.5 to 0.8, where D c  represents the diameter, and H represents the height of the molding member  132  (a distance from the top surface  134  to the lower-side edge portion  144 ). 
     Also, in the case where part of the molding member  132  is constituted with graphite, for the reason described earlier, portions of the molding member  132  that come into contact with the molten glass MG and/or the glass ribbon GR may be constituted with a material other than graphite. Alternatively, the contacting portions may be covered or coated with a material that does not react with glass. 
     Also, conversely, in the molding member  132 , the top surface  134  may be constituted with graphite. As described earlier, in the case where the top surface  134  is constituted with graphite, processing is relatively easy, and hence, the top surface  134  can be formed to be relatively smooth. Therefore, in this case, the distribution of the molten glass MG flowing out of the top surface  134  can be made uniform, and the dimensional precision can be increased for the plate glass  194  to be obtained finally. 
     Note that in this case, the molten glass MG comes into contact with graphite. However, even if both come into contact, as long as the contact lasts for a short period of time, the problem of graphite-derived components being mixed into the plate glass  194  is considered not to be noticeable significantly. 
     As above, with reference to  FIGS. 1 to 3 , the configuration and features of the first production apparatus  100  have been described. However, the configuration described above is merely an example, and it is apparent that the first production apparatus  100  may have other configurations. 
     For example, in the example illustrated in  FIGS. 1 to 3 , in the first production apparatus  100 , the cooling rollers  182  and  184  of the slow cooling part  180  are arranged downstream of the fence  150  covering the molding member  132 . However, the cooling rollers  182  and  184  of the slow cooling part  180  may be included in the fence  150 . In other words, at least part of the slow cooling part  180  may be included in the fence  150 , to partially execute the slow cooling down of the glass ribbon GR in the fence  150 . 
     For example, if at least part of the slow cooling part  180  is included in the fence, the viscosity of the glass ribbon GR discharged from the fence  150  may be greater than or equal to 10 13  poise. In this case, an advantage is obtained that the slow cooling of the glass ribbon can be executed relatively easily. 
     (Another Plate Glass Production Apparatus According to an Embodiment of the Present Disclosure) 
     The first production apparatus  100  including the molding member  132  described earlier is an apparatus that produces plate glass by the fusion process. However, the plate glass production apparatus, in particular, the molding member to which the present disclosure can be applied is not limited as such. The present disclosure can also be applied to plate glass production apparatuses using other production methods, and to molding members used in such production apparatuses. 
     Thereupon, next, with reference to  FIG. 4 , another plate glass production apparatus according to an embodiment of the present disclosure will be described. 
       FIG. 4  schematically illustrates part of another plate glass production apparatus  200  according to an embodiment of the present disclosure (hereafter, referred to as the “second production apparatus”). The second production apparatus  200  is an apparatus that produces plate glass by the so-called slit molding process (down-draw process). 
     As illustrated in  FIG. 4 , the second production apparatus  200  includes a molding part  230 , a slow cooling part  280 , and a cutting part (not illustrated). 
     Note that although the example illustrated in  FIG. 4  does not illustrate a melting part to form an molten glass MG, in the second production apparatus  200 , a melting part may be provided upstream of the molding part  230 . Alternatively, the molten glass MG may be formed in the molding part  230 . In this case, the melting part is omitted. 
     The molding part  230  has a molding member  232  arranged. The molding part  230  may further have rollers arranged (not illustrated). Also, the slow cooling part  280  has at least one pair of cooling rollers  282  arranged. 
     The molding member  232  includes an internal side surface  238 , an internal bottom surface  244 , and an external bottom surface  245 . The molding member  232  can contain the molten glass MG in an interior compartmentalized by the internal side surface  238  and the internal bottom surface  244 . A slit  247  is formed to penetrate both from the internal bottom surface  244  to the external bottom surface  245 . 
     Note that although not apparent from  FIG. 4 , each part of the molding member  232  extends in a direction perpendicular to the plane of the paper. Therefore, the molding member  232  illustrated in  FIG. 4  has an elongated shape along the longitudinal direction (assumed to be the X direction). 
     The molding member  232  is constituted with graphite. 
     Also, a fence  250  is provided around the molding member  232 , and the surroundings of the molding member  232  is covered by the fence  250 . In other words, the fence  250  forms a space  252  around the molding member  232 . However, as is clear from  FIG. 4 , the fence  250  has a removed portion, through which the glass ribbon GR is discharged toward the slow cooling part  280 . Therefore, the glass ribbon GR formed in the molding part  230  can be moved to the slow cooling part  280  without being interfered by the fence  250 . 
     During operation of the second production apparatus  200 , the space  252  is controlled to have an oxygen concentration of less than or equal to 100 ppm. Also, in order to make this possible, a gas inlet  254  is provided at a predetermined position on the fence  250 . An open/close valve may be provided in the gas inlet  254 . Also, if necessary, the fence  250  may also be further provided with a gas outlet (not illustrated). 
     The oxygen concentration of the space  252  can be controlled within the range described earlier, by supplying gas having a predetermined composition from the gas inlet  254 , or exhausting the gas from the gas outlet. 
     In the case of producing plate glass using the second production apparatus  200  as such, first, raw materials for glass is melted in a melting part (not illustrated), to form the molten glass MG. Also, the molten glass MG is supplied to the molding member  232  of the molding part  230 . 
     Alternatively, as described earlier, in the case where there is no melting part, the molten glass MG may be produced from the raw materials for glass in the molding member  232  of the molding part  230 . 
     Next, the molten glass MG supplied to the molding member  232  or produced in the molding member  232  flows out downward through the slit  247  of the molding member  232 . At this time, the shape (thickness) of the molten glass MG is adjusted, to form a glass ribbon GR. 
     Thereafter, the glass ribbon GR is towed downward by rollers arranged in the molding part  230  (not illustrated) and cooling rollers  282 , and supplied to the slow cooling part  280 . In the slow cooling part  280 , the glass ribbon GR is slowly cooled down to a predetermined temperature. 
     Thereafter, the slowly-cooled glass ribbon GR is supplied to a cutting part (not illustrated), and cut into predetermined dimensions. Accordingly, the plate glass is produced. 
     In the second production apparatus  200 , the molding member  232  is constituted with graphite. Therefore, in the second production apparatus  200 , the conventional problem of deformation by creep can be suppressed significantly. 
     Also, in the second production apparatus  200 , the molding member  232  is covered with the fence  250 , and the interior space  252  is controlled to be a low oxygen environment with an oxygen concentration of less than or equal to 100 ppm. Therefore, in the second production apparatus  200 , even when graphite is used for the molding member  232 , the molding member  232  can be prevented from degrading due to oxidation. 
     As a result, in the second production apparatus  200 , creep is unlikely to occur in the molding member  232 , and deformation and bends of the molding member  232  can be suppressed significantly. 
     Also, accordingly, even after the second production apparatus  200  would have been used for a long period of time, the dimensions of produced plate glass can be maintained with high precision. 
     Also in the second production apparatus  200 , the molding member  232  does not need to be constituted with graphite entirely. In other words, part of the molding member  232  may be constituted with graphite. For example, graphite may be applied at a position where the creep resistance characteristic of the molding member  232  is likely to be improved, and/or in a shape with which the creep resistance characteristic of the molding member  232  is likely to be improved. 
     In this case, in general, the volume ratio of graphite to the entire molding member  232  is greater than or equal to 50%, favorably greater than or equal to 60%, more favorably greater than or equal to 70%, and even more favorably greater than or equal to 80%. 
     For example, graphite may be applied to the molding member  232  as a bottom surface material constituting the internal bottom surface  244  through the external bottom surface  245 . 
     Also, as has been described with the first production apparatus  100 , in the case where part of the molding member  232  is constituted with graphite, portions of the molding member  232  that come into contact with the molten glass MG and/or the glass ribbon GR may be constituted with a material other than graphite. This is to prevent the plate glass to be produced from containing graphite-derived components. 
     Alternatively, in the molding member  232 , the part constituting the slit  247  may be constituted with graphite. As described earlier, graphite is relatively easy to process; therefore, in the case of constituting a portion corresponding to the slit  247  with graphite, the smooth slit  247  can be formed to be relatively smooth. 
     Therefore, in this case, the distribution of the molten glass MG flowing out of the slit  247  can be made uniform, and the dimensional precision can be increased for the plate glass to be obtained finally. 
     Note that as described earlier, when the molten glass MG comes into contact with graphite, the problem of graphite-derived components mixed into the glass is considered not be noticeable significantly if the contact time is short. 
     Also in the second production apparatus  200 , the cooling rollers  282  of the slow cooling part  280  may be contained in the interior of the fence  250  that covers the molding member  232 . In other words, in the fence  250 , at least part of the slow cooling down of the glass ribbon GR may be executed. 
     (Yet Another Plate Glass Production Apparatus According to an Embodiment of the Present Disclosure) 
     Next, with reference to  FIG. 5 , yet another plate glass production apparatus according to an embodiment of the present disclosure will be described. 
       FIG. 5  schematically illustrates part of yet another plate glass production apparatus  300  according to an embodiment of the present disclosure (hereafter, referred to as the “third production apparatus”). The third production apparatus  300  is an apparatus that produces plate glass by the so-called slit molding process (down-draw process). 
     As illustrated in  FIG. 5 , the third production apparatus  300  basically has substantially the same configuration as the second production apparatus  200  described earlier. Therefore, in the third production apparatus  300 , each member that is substantially the same as the corresponding member used in the second production apparatus  200  is assigned a reference numerals obtained by adding  100  to the reference code of the corresponding member illustrated in  FIG. 4 . For example, the third production apparatus  300  includes a molding member  332 , a fence  350 , and a pair of cooling rollers  382 , and the like. 
     However, the third production apparatus  300  further includes a support member  370 , and in this regard, differs from the second production apparatus  200 . 
     The support member  370  is arranged on the lower side of the molding member  332 , so as to support the molding member  332 . The support member  370  is arranged so as to contact (at least part of) an external side surface  339  and (at least part of) an external bottom surface  345  of the molding member  332 . 
     The support member  370  is constituted with graphite. Alternatively, the support member  370  contains graphite. 
     The fence  350  is arranged around the molding member  332  and the support member  370 , and by this fence  350 , a space  352  is formed around the molding member  332  and the support member  370 . However, as is clear from  FIG. 5 , the fence  350  has a removed portion, through which the glass ribbon GR is discharged toward the slow cooling part  380 . Therefore, the glass ribbon GR formed in the molding part  330  can be moved to the slow cooling part  380  without interfered by the fence  350 . 
     During operation of the third production apparatus  300 , the space  352  is controlled to have an oxygen concentration of less than or equal to 100 ppm. 
     The production method of plate glass using the third production apparatus  300  as such is basically the same as in the case of the second production apparatus  200 . Therefore, here, the detailed description is omitted. 
     In the third production apparatus  300 , the molding member  332  is supported by the support member  370  containing graphite. Therefore, also in the third production apparatus  300 , the problem of the molding member  332  deforming due to creep can be suppressed significantly. 
     Also, in the third production apparatus  300 , the support member  370  is covered with the fence  350 , and the interior space  352  is controlled to be a low oxygen environment with an oxygen concentration of less than or equal to 100 ppm. Therefore, in the third production apparatus  300 , even when graphite is used for the support member  370 , the support member  370  can be prevented from degrading due to oxidation. 
     As a result, in the third production apparatus  300 , creep is unlikely to occur in the molding member  332 , and deformation and bends of the molding member  332  can be suppressed significantly. 
     Also, accordingly, even after the third production apparatus  300  would have been used for a long period of time, the dimensions of produced plate glass can be maintained with high precision. 
     Also in the third production apparatus  300 , the cooling rollers  382  of the slow cooling part  380  may be contained in the fence  350  that covers the molding member  332 . In other words, in the fence  350 , at least part of the slow cooling down step of the glass ribbon GR may be executed. 
     As above, the configurations and features according to the present inventive concept have been described with reference to the first production apparatus  100  to the third production apparatus  300 . 
     However, these are merely examples, and it is apparent that the present inventive concept may have other configurations. 
     For example, in the third production apparatus  300 , the molding member  332  is supported by the support member  370  containing graphite. In these configurations, further, the molding member  332  may be constituted with graphite, or may contain graphite. 
     In addition, it is apparent to those skilled in the art that various combinations and/or changes are conceivable.