JP2010006665A - Method for producing plate-like glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve productivity by preventing cracks or the like in a production process of a plate-like glass. <P>SOLUTION: A glass made to continuously flow out from a melting furnace is brought into slidable contact with one or more rolling rollers while being conveyed by a conveyer to thereby be molded into a plate-like shape, both edge parts of the glass molded into a plate-like shape are removed, and the surface of the glass from which both edge parts have been removed is polished. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a glass sheet by forming molten glass flowing out of a glass melting furnace into a sheet shape.

  A solid-state imaging device such as a CCD or CMOS used for a digital still camera or the like has a spectral sensitivity ranging from a visible light region to a near infrared region near 1100 nm. Therefore, since excellent color reproducibility cannot be obtained as it is, the visibility is corrected using a near-infrared cut filter glass to which a specific substance that absorbs infrared rays is added. As this near-infrared cut filter glass, optical glass in which CuO is added to fluorophosphate glass has been developed and used so as to selectively absorb wavelengths in the near-infrared region and have high weather resistance (Patent Document 1). : JP-A-6-16451).

It is known that the viscosity of a fluoride glass such as fluorophosphate glass rapidly decreases as the temperature increases, and has already decreased to 10 ⁻² Pa · s near the liquidus temperature (about 1000 ° C.). Therefore, applying the roll-out method, which is one of the methods for forming sheet glass, and conveying the molten fluorophosphate glass while being sandwiched between the rolls means that the viscosity in the molten state is low and the melt is performed between the rolls. It is extremely difficult because the glass flows down.

  In view of such a problem, the present applicant has applied for a molding method capable of suitably molding glass having a low viscosity in a molten state such as fluorophosphate glass (Patent Document 2: JP-A No. 2003-171127). . The present invention has a step of individually adjusting the surface temperature of the rolling roller based on the surface temperature of the processed and molded glass detected in the temperature detection step, and generates striae, distortion, for example, fluorophosphate glass In this case, the glass sheet forming method can form the glass sheet with high precision and efficiency while suppressing the volatilization loss of fluorine.

Japanese Patent Laid-Open No. 6-16451 JP 2003-171127 A

  However, the plate-like glass obtained as described above has a problem in that cracking is likely to occur in the subsequent slow cooling process and polishing process, productivity is deteriorated, and material is wasted.

  It is an object of the present invention to improve productivity by preventing cracks and the like in the manufacturing process of sheet glass.

In order to solve the above problems, the present invention provides:
A first step of forming the glass into a plate shape by sliding one or more rolling rollers while conveying the glass continuously flowing out of the melting furnace by a conveyor;
A second step of removing both ends of the plate-shaped glass;
A third step of polishing the surface of the glass from which both ends have been removed;
It is related with the manufacturing method of sheet glass characterized by comprising.

  The present inventors have intensively studied to solve the above problems. As a result, the following facts were found.

  When forming glass with low viscosity in a molten state such as fluorophosphate glass or glass with steep temperature characteristics of viscosity, the sheet glass formed by a method using a rolling roller and a conveyor is at the center in the width direction. Compared to this, the thickness of both end portions tends to increase. The reason for this is that the glass that has passed through the gap between the rolling roller and the conveyor is not sufficiently cooled and still has a low viscosity. For this reason, the sheet thickness in the width direction is once uniform by passing through the rolling roller, but the glass viscosity is low. , Both ends become thick.

  The fluctuation of the plate thickness in the width direction of the plate glass as described above is not sufficient although it is compensated to some extent by the auxiliary roller provided at the subsequent stage of the conveyor. In particular, there is a large difference in the thickness of the glass before and after passing through the rolling roller, that is, when trying to reduce the thickness of the sheet glass by increasing the rolling amount by the rolling roller relative to the original thickness, both ends in the width direction The thickness tends to be remarkably thick, and the plate thickness distribution of the sheet glass is remarkably increased.

  For this reason, in the slow cooling process, the thermal stress generated in the sheet glass becomes non-uniform so that cracks occur in the sheet glass, and in the polishing process, the load concentrates on the end portion to cause the plate shape. It has been found that cracks are likely to occur in glass. Therefore, in the present invention, by actively removing the end portion of the sheet glass that causes such cracking, the end portion of the sheet glass is prevented from being cracked due to being formed thick. Is. Specifically, the edge is removed before the surface of the sheet glass is polished.

  As is clear from the above description, the present invention is caused by the fact that the cracks in the glass sheet increase the thickness in the width direction particularly in the manufacturing process, and the non-uniformity in the thickness distribution. It was made based on the investigation of the cause of being.

  Moreover, since the processing amount of the both ends in the said grinding | polishing process will increase when the edge part of the said sheet glass becomes thick, the edge part removal of the plate glass mentioned above makes the said grinding | polishing process efficient, ie, the efficiency of a manufacturing process. It is also effective from the viewpoint of optimization.

  In general, the polishing step is divided into a primary polishing process for smooth and rough polishing of the surface of the glass plate and a secondary polishing process for smooth and precise polishing of the surface of the roughly polished glass plate. However, the polishing treatment in the present invention means the former, that is, the primary polishing treatment.

  In the present invention, as a secondary effect, the removed glass at both ends can be reused as a glass raw material as a cullet, so that waste of materials can be saved and resource saving can be achieved. In addition, no extra steps such as industrial waste processing are required. Note that polishing scraps cannot be reused as a glass raw material because an abrasive or the like is mixed therein. Furthermore, since the size (area) of the glass in the polishing process is reduced, the number of glasses that can be put into one polishing process can be increased, and the efficiency of the manufacturing process can be increased.

  In one aspect of the present invention, a fourth step of cutting the plate-shaped glass in a direction orthogonal to the transport direction can be provided. In this case, the second step of removing both end portions of the sheet glass can be performed after the fourth step, or can be performed before the fourth step.

  For example, when the plate glass is made of, for example, fluorophosphate glass, an inhomogeneous layer such as striae is included at the end of the glass. Further, the end portion has a wavy indefinite shape. Therefore, in the step of removing the end portion of the sheet glass described above, it is preferable that the inhomogeneous layer and the irregularly shaped portion included in the end portion are removed together. Thereby, the defects in the glass sheet described above can be removed at the same time in the above-described removal process of both ends, and there is no need to provide a separate process for removing the defects. As a result, the entire manufacturing process can be simplified when it is required to remove the defects.

  As described above, according to the present invention, it is possible to prevent the cracking and the like in the production process of the sheet glass and improve the productivity.

  Hereinafter, other features and advantages of the present invention will be described in detail based on the best mode for carrying out the invention.

  FIG. 1 is a perspective view schematically showing a main part of a sheet glass forming apparatus used in the method for producing a sheet glass of the present invention, and FIG. 2 shows a state near a rotary blade of the apparatus shown in FIG. FIG.

  A plate-like glass forming apparatus 1 shown in FIG. 1 includes a melting furnace 2 in which a molten glass 3 a is placed, a conveyor 4 provided below the melting furnace 2, and a conveying direction of the conveyor 4. A plurality of rolling rollers 6, a plurality of auxiliary rollers 7, a pair of rotary blades 8, and a cutting unit 9 are sequentially provided forward. A pair of guide members 10 are provided on the side of the conveyor 4 so as to hang from the position below the melting furnace 2 and before the rotary blade 8.

  The melting furnace 2 has an opening 2 a below, and is configured to allow a predetermined amount of molten glass to flow out onto the conveyor 4.

  Here, the conveyor 4 is an endless chain in which a plurality of strip-shaped plates 4a are connected on a rail. Each plate 4a is formed of a material having excellent heat resistance and corrosion resistance. The contact surface of the plate 4a with the glass 3a and the sliding surface of the guide member 8 are extremely smooth in order to finish the surface of the sheet glass to be molded smoothly and to suppress wear between the plate 4a and the guide 7. It has been finished.

  Examples of the material of the plate 4a include stones and ceramics, as well as metals such as stainless steel such as SUS304, SUS304L, SUS321, SUS316, SUS316L, and SUS310S. Further, in the conveyor 4, the individual plates 4a are connected so that the molten glass 3a does not flow into the gap between the adjacent plates 4a so that the gap is 1 mm or less.

  For example, six sets of rolling rollers 6 are provided so as to face the conveyance surface of the glass 3a of the conveyor 4. Further, the longitudinal direction of the rolling rollers 6 is arranged so as to be orthogonal to the conveying direction of the glass 3a of the conveyor 4, and each of them is arranged in parallel from the upstream side to the downstream side. The rolling roller 6 is made of a metal material having excellent heat resistance and corrosion resistance. Cooling water is allowed to flow inside the rolling roller 6 and is cooled with water.

  The auxiliary roller 7 is provided on the downstream side of the rolling roller 6 in the glass conveyance direction of the conveyor 4, and for example, three sets are provided so as to face the glass conveyance surface of the conveyor 4. Further, these auxiliary rollers 7 are arranged such that the longitudinal direction is orthogonal to the glass conveying direction of the conveyor 4, and each auxiliary roller 7 is arranged in parallel from the upstream side to the downstream side. As with the rolling roller 6, the auxiliary roller 7 is made of a metal material having excellent heat resistance and corrosion resistance. Cooling water is caused to flow inside the auxiliary roller 7 and the auxiliary roller 7 is cooled with water. In addition, when the plate-shaped molded glass 3b of uniform plate | board thickness is obtained only with the rolling roller 6, these auxiliary rollers 7 can be abbreviate | omitted.

  The rotary blade 8 is provided on the downstream side of the auxiliary roller 7 in the glass conveying direction of the conveyor 4, and is provided so as to be in contact with both end portions 3 c of the plate-shaped glass 3 b that passes through the auxiliary roller 7. The rotary blade 8 is rotatably attached to a rotary shaft in a direction orthogonal to the glass conveyance direction. The rotary blade 8 is adjusted to a state in which the blade edge portion is close enough not to contact the conveyor 4 supporting the lower side of the plate-shaped glass 3b. As a result, the plate-shaped glass 3b comes into contact with the rotary blade 8 and the both end portions 3c are cut and removed. The rotary blade 8 can be composed of a general-purpose tool such as a diamond blade.

  Each of the guide members 10 is formed with a uniform thickness, and is formed of a metal having excellent heat resistance and corrosion resistance. The contact surfaces of the conveyor 4 and the rolling roller 6 with the outer cylinder are finished extremely smoothly in order to suppress mutual wear. Further, a pipe (not shown) formed with an outer diameter that is substantially the same as or slightly smaller than the thickness of the guide member 10 is disposed on the contact surface of each guide member 10 with the glass. The cooling water for cooling the guide member 10 heated by the glass flows.

  The molten glass 3a that has flowed out of the melting furnace 2 onto the conveyor 4 is continuously conveyed by the conveyor 4, and the surface thereof is slidably contacted with the plurality of rolling rollers 6 to be rolled in the thickness direction. Thereafter, the glass 3 a in the molten state is adjusted in shape in the thickness direction by its surface being in sliding contact with the plurality of auxiliary rollers 7. At this time, the conveyance width of the molten glass 3a is regulated by the guide member 10 and is defined. In this way, the molten glass 3a is molded into a plate-shaped molded glass 3b.

  Then, after the both ends 3c are cut and removed by the pair of rotary blades 8 (see FIG. 2), the plate-shaped glass 3b is sent to the cutting unit 9 and cut in a direction perpendicular to the conveying direction. As a result, a plate-shaped glass having a predetermined length and width is continuously formed from the plate-shaped glass 3b.

  The plate-shaped glass 3b cut to a predetermined size is then placed in a polishing machine (not shown) and subjected to a polishing process (lapping process). Normally, the polishing machine is a batch type, and a plurality of plate-shaped glass 3b are set and batch processing is performed.

  In the polishing process, a plurality of plate-shaped glass 3b held by a carrier is sandwiched between a lower surface plate and an upper surface plate made of a casting. And while supplying an abrasive | polishing agent and polishing liquid between both the grinding | polishing surface of a lower surface plate and an upper surface plate, and the upper and lower surfaces of the to-be-polished surface of the plate-shaped shaping | molding glass 3b, a lower surface plate and an upper surface plate are driven by a drive part. Rotate at a predetermined speed. As a result, the carrier performs a planetary motion between the lower surface plate and the upper surface plate, and the surface to be polished is polished by the relative movement of the lower surface plate and the upper surface plate and the plate-shaped glass 3b due to the planetary motion.

  When the glass 3a is a low-viscosity glass such as fluorophosphate glass or a glass having a steep temperature characteristic of viscosity, the glass 3a is not sufficiently cooled even after passing through the gap between the rolling roller 6 and the conveyor 4. The viscosity is still low. For this reason, although the plate | board thickness of the width direction becomes uniform once, since the viscosity of glass is low, the center part of the width direction deform | transforms thinly by being pulled to both ends by the surface tension, and both ends become thick.

  Such plate thickness variation after passing through the rolling roller 6 can be compensated to some extent by subsequently passing through the auxiliary roller 7, but it is not sufficient.

  However, in the present embodiment, as described above, both ends 3c are actively cut by the pair of rotary blades 8 before the plate-shaped glass 3b is supplied to the cutting unit 9, that is, before the polishing process. Try to remove. Therefore, the plate thickness distribution in the width direction of the plate-shaped glass 3b becomes extremely uniform by passing through the rotary blade 8 and cutting and removing both end portions 3c.

  As a result, the thermal stress generated in the plate-shaped glass 3b becomes uniform in the slow cooling process when transported from the rotary blade 8 to the cutting unit 9 and further to the polishing processor. Moreover, it can suppress that a load concentrates on the edge part of the plate-shaped shaping | molding glass 3b at a grinding | polishing process. Therefore, it is possible to suppress cracking due to the thermal stress of the plate-shaped glass 3b or load concentration on the end portion in the polishing process. For this reason, the frequency of occurrence of cracks in the plate-shaped glass 3b in the manufacturing process can be drastically reduced, and the manufacturing yield can be improved.

  In addition, since the processing amount of the both ends in the said grinding | polishing process will increase when the edge part becomes thick compared with the center part of the shaping | molding width direction, the plate-shaped glass 3b removes the edge part of the plate-shaped glass mentioned above. This is also effective from the viewpoint of increasing the efficiency of the polishing process, that is, increasing the efficiency of the manufacturing process.

  Moreover, since the both ends which removed the plate-shaped shaping | molding glass 3b can be reused as a glass raw material as a cullet, waste of material can be saved and resource saving can be achieved. In addition, no extra steps such as industrial waste processing are required.

  Furthermore, since the both end portions 3c of the plate-shaped molded glass 3b are removed in advance, the size of the plate-shaped molded glass 3b set in the polishing processing machine described above is reduced. Therefore, it is possible to increase the number of the plate-shaped glass 3b that can be charged in one process (one batch), and to increase the efficiency of the polishing process, that is, the manufacturing process.

  When the plate-shaped glass 3b, that is, the glass 3a is made of, for example, fluorophosphate glass or the like, a heterogeneous layer such as striae is included at the end of the plate-shaped glass 3b. Further, the end portion has a wavy indefinite shape. Therefore, when removing the end portion of the plate-shaped glass 3b with the rotary blade 8, the nonuniform layer and the irregular shape portion are included in the end portion 3c to be removed. Defects such as a homogeneous layer can be removed simultaneously in the above-described removal process at both ends. Accordingly, it is not necessary to provide a separate process for removing the defect, and therefore the entire manufacturing process can be simplified when it is required to remove the defect.

  1 and 2, after obtaining a plate-shaped glass made of fluorophosphate glass having a width of 145 mm, both ends thereof are cut with a rotary blade (diamond blade) by 12.5 mm, and then with a cutting unit. Cut to a length of 145 mm, a plate-shaped glass having a width of 120 mm and a length of 145 mm was obtained.

  Then, the said plate-shaped molded glass was set in the grinding | polishing processing machine, and grinding | polishing processing was implemented. At this time, 20 plate-shaped molded glasses could be set per batch in the polishing machine.

  On the other hand, for comparison, a plate-shaped glass having a width of 145 mm and a length of 145 mm was obtained without cutting both ends with a rotary blade in the apparatus of FIG. Then, the said plate-shaped molded glass was set in the grinding | polishing processing machine, and grinding | polishing processing was implemented. At this time, 15 plate-like formed glasses could be set per batch in the polishing machine. That is, according to the present invention, when both ends of the plate-shaped glass are cut, the number of sheets processed per batch in the polishing machine of the plate-shaped glass can be increased. It can be seen that the efficiency of the process can be improved.

  Table 1 shows the frequency of occurrence of cracks after each plate-shaped glass was polished. As is clear from Table 1, when both ends of the sheet-shaped glass are cut according to the present invention, the frequency of occurrence of cracks is drastically reduced, and a production yield of 90% or more is obtained, whereas It was found that when both ends were not cut, the frequency of cracking was relatively high, and only a production yield of around 80% was obtained. That is, according to the present invention, it was found that by cutting and removing both end portions of the plate-shaped glass in advance before the polishing treatment, cracking of the plate-shaped glass can be suppressed, and the production yield can be improved. .

  Moreover, the nonuniformity of the plate | board thickness by cutting and removing of the both ends of plate-shaped molded glass was evaluated. About the plate-shaped molded glass shape | molded with the apparatus of the said FIG. 1, the surface which contacted the conveyor 4 at the time of shaping | molding was mounted on the surface plate, and the height of the center part was measured. Measurements were made on 100 sheets each of which both ends were cut and removed with a rotary blade, and both ends were not cut and removed for comparison, and the average of about 2.6 mm was obtained by cutting and removing both ends. What was not removed by cutting was an average of about 2.8 mm. In other words, by cutting and removing both end portions that are formed thicker than the central portion in the forming width direction, the plate-shaped glass sheet thickness is about 0.2 mm lower, and the unevenness of the plate thickness is improved. You can see that

  While the present invention has been described in detail based on the above specific examples, the present invention is not limited to the above specific examples, and various modifications and changes can be made without departing from the scope of the present invention.

  For example, in the above embodiment, after the plate-shaped glass 3b is formed, both ends are cut and removed before being cut into a predetermined length by the cutting unit 9, but the cutting unit 9 has a predetermined length. After cutting, both ends can be cut and removed. In this case, similarly to the above-described polishing treatment, a cutting device is separately prepared in addition to the molding device shown in FIG. 1, and both ends are cut by using the plate-shaped glass 3b for the cutting device.

Moreover, in the said embodiment, although the both ends of the plate-shaped shaping | molding glass 3b are cut and removed by the rotary blade 8, it can also cut and remove by irradiation of a laser beam.
Furthermore, in the said embodiment, although the both ends of the plate-shaped glass 3b are directly cut and removed by the rotary blade 8, after grooving the plate-shaped glass 3b, both ends are removed by breaking. You can also

  Further, in the apparatus shown in FIG. 1, the state of the molten glass 3a flowing out from the melting furnace 2 onto the conveyor 4 is imaged by an imaging apparatus (not shown), and a predetermined control signal is obtained by performing arithmetic processing on the obtained image. Further, the rotational speed of the rolling roller 6 and the auxiliary roller 7 and the gap with the conveyor 4 can be controlled so that a plate-shaped glass 3b having a target thickness can be obtained.

It is a perspective view which shows typically the principal part of the sheet glass shaping | molding apparatus used for the manufacturing method of the sheet glass of this invention. It is a figure which expands and shows the mode of the rotary blade vicinity of the apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Molding apparatus 2 Melting furnace 3a Glass in molten state 3b Plate-shaped molded glass 4 Conveyor 6 Rolling roller 7 Auxiliary roller 8 Rotary blade 9 Cutting unit 10 Guide member

Claims (7)

A first step of forming the glass into a plate shape by sliding one or more rolling rollers while conveying the glass continuously flowing out of the melting furnace by a conveyor;
A second step of removing both ends of the plate-shaped glass;
A third step of polishing the surface of the glass from which both ends have been removed;
A method for producing sheet glass, comprising:   2. The method according to claim 1, further comprising a fourth step of cutting the glass formed into a plate shape in a direction orthogonal to a conveyance direction, wherein the second step is performed after the fourth step. The manufacturing method of plate glass of description.   2. The method according to claim 1, further comprising a fourth step of cutting the glass formed into a plate shape in a direction orthogonal to a conveyance direction, wherein the second step is performed before the fourth step. The manufacturing method of plate glass as described in 2.   The both ends from which the said glass is removed include a heterogeneous layer, The manufacturing method of the sheet glass as described in any one of Claims 1-3 characterized by the above-mentioned.   The both ends from which the said glass is removed are irregular shapes, The manufacturing method of the sheet glass as described in any one of Claims 1-3 characterized by the above-mentioned.   The both ends where the said glass is removed are shape | molded thickly with respect to the center part of a shaping | molding width direction in the said 1st process, The plate shape in any one of Claims 1-5 characterized by the above-mentioned. Glass manufacturing method.   The said glass contains a fluorine, The manufacturing method of the sheet glass as described in any one of Claims 1-6 characterized by the above-mentioned.

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