JP7649483B2 - Glass plate manufacturing method and manufacturing device - Google Patents

Description

The present invention relates to a glass sheet manufacturing technology, and more specifically, to detecting defects that occur in a glass ribbon or glass sheet after the glass ribbon is cut to produce glass sheets.

Methods that are widely used to manufacture glass sheets include downdraw methods such as the overflow downdraw method, the slot downdraw method, and the redraw method.

In the glass sheet manufacturing process using these techniques, a glass ribbon is continuously formed, then the glass ribbon is cut widthwise at specified lengths, and glass sheets are cut out from the glass ribbon. During this process, defects may occur in the glass ribbon or glass sheets.

For example, Patent Document 1 discloses a method in which multiple laser sensors are used to detect the presence or absence of glass in the glass ribbon or glass sheet after cutting, and the presence or absence of defects (called breakage in the document) that occur in these sheets is automatically monitored based on the detection results. The laser sensors used here are reflective sensors that irradiate the glass ribbon or glass sheet with laser light and detect the light reflected by the glass.

JP 2018-104228 A

However, in the case of laser sensors, when the glass ribbon or glass plate sways or vibrates on the transport path, the state of the light to be measured, such as the reflected light obtained from the laser light irradiated toward them, easily fluctuates. As a result, there is a problem of false detection of defects occurring in the glass ribbon or glass plate, and there is a demand for a method to detect these defects with higher accuracy.

From the above perspective, the present invention aims to detect defects occurring in the measurement object, which is either the cut side end of the glass ribbon after cutting, the glass plate, or either of the two, with high accuracy.

The first aspect of the present invention, which has been invented to solve the above problems, is a glass sheet manufacturing method comprising a forming step of forming a glass ribbon in a forming zone, a conveying step of conveying the glass ribbon along the longitudinal direction, and a cutting step of cutting the glass ribbon along the width direction to cut out glass sheets, characterized in that the method comprises a detection step of measuring the temperature of the cut end of the glass ribbon after cutting in the cutting step, the glass sheet, or either one of them as a measurement object, and detecting defects occurring in the measurement object based on the measurement results. Here, "defect" refers to defects such as defects (including irregular shapes) and breakage occurring in the measurement object, and a measurement object in which such a defect occurs becomes a defect (defective product) itself (the same applies below).

According to this method, when the measurement object is the cut end of the glass ribbon, defects occurring at the cut end are detected; when the measurement object is a glass plate, defects occurring in the glass plate are detected; and when the measurement object is both the cut end of the glass ribbon and the glass plate, defects occurring in the cut end and the glass plate are detected. When detecting defects, the temperature of the measurement object does not change significantly even if the position of the measurement object fluctuates due to shaking or vibration on the transport path, but shows a large change at points where glass is missing or protruding in the measurement object. Therefore, according to this method, defects occurring in the measurement object can be detected with high accuracy.

In this method, the cutting process may involve cutting out the glass plate by bending and breaking the glass ribbon along scribe lines extending in the width direction of the glass ribbon.

In this way, it is possible to detect with high accuracy specific defects that occur in the cut end of the glass ribbon and the glass sheet after cutting when the glass ribbon is cut by bending and breaking. In other words, in the cutting process, the glass ribbon can be cut by laser breaking or laser melting, etc., but when the glass ribbon is cut by bending and breaking, specific defects occur that are different from those caused by other methods. With the configuration described here, it is possible to appropriately deal with such specific defects.

In the above method, the forming step may form the glass ribbon by a down-draw method, and the detection step may measure the temperature of the measurement object in a vertical position by measuring the temperature distribution using a thermograph. Here, a vertical position refers to a vertical position or an inclined position that is less than 45° with respect to the vertical direction (hereinafter the same).

Temperature distribution can be measured using multiple temperature sensors arranged along the width of a vertically oriented glass ribbon or glass plate, but the use of thermography makes it possible to obtain highly precise temperature distribution and reliably detect even small defects.

In this method, the defects detected in the detection process may include a shape defect of the upper cut surface of the glass plate after cutting in the cutting process.

Defective shapes on the upper cut surface of a glass sheet are often caused by, for example, wear and tear on the scribe tip or wheel cutter. If this defective shape is detected, appropriate measures can be taken, such as replacing the scribe tip or wheel cutter, and the occurrence of defective shapes on the upper cut surface of subsequent glass sheets can be prevented.

In this method, the distribution of height positions of the upper cut surface may be calculated from the temperature distribution of the glass plate, and shape defects of the upper cut surface may be detected based on the height distribution.

In this way, by measuring the height from the distribution of height positions on the cut surface on the upper side of the glass plate, defects in the shape of the cut surface can be detected, and the detection process can be optimized. In this case, the thermal image showing the temperature distribution taken by thermography depicts the boundary between the low-temperature area, which is the space above the glass plate, and the high-temperature area where the glass plate is present, as the shape of the cut surface. Then, by performing image analysis etc. based on the height of this boundary line, defects in the shape of the cut surface can be accurately detected.

In this method, if a defect in the shape of the upper cut surface is detected, the glass plate may be discarded.

In this way, the glass plate can be discarded early as soon as a defect in the shape of the upper cut surface is detected, preventing contamination of the manufacturing line in subsequent processes.

In these methods, the defects detected in the detection process may include partial breakage of the glass plate after cutting in the cutting process.

Partial breakage is more likely to occur, for example, when the warp in the glass ribbon is large. If partial breakage is detected, appropriate measures can be taken, such as reducing the warp in the glass ribbon, and partial breakage can be prevented from occurring in subsequent glass sheets.

In this method, the area of at least a portion of the glass plate may be calculated from the temperature distribution of the glass plate, and partial damage may be detected based on the area and a first threshold value.

In this way, partial damage is detected based on the area of at least a part of the glass plate and the first threshold value, so that accurate detection with less error is possible. In this case, in the thermal image showing the temperature distribution by thermography, a low-temperature drawing corresponding to partial damage appears in a part of the part where a high-temperature drawing should be made due to the presence of the glass plate. Then, the area of only the high-temperature part is obtained, and partial damage is detected based on this area and the first threshold value. In this case, the area of the glass plate is, for example, the area of the part of the glass plate when the area that can be measured by thermography is a part of the glass plate, and the area of the entire glass plate when the area that can be measured by thermography is the entire glass plate. This area can be obtained by the number of pixels in the thermal image, etc. The first threshold value here is set to, for example, 90% to 99% of the area of the glass plate when there is no defect (the area corresponding to the above-mentioned area). Therefore, if the area of the high-temperature part in the thermal image exceeds the first threshold value, it is not considered to be partial damage, and if it is equal to or less than the first threshold value, it is detected as partial damage.

In this method, if partial damage is detected, the glass plate may be discarded.

In this way, the glass plate can be discarded early when partial damage is detected, thereby preventing contamination of the manufacturing line in subsequent processes.

In these methods, the defects detected in the detection process may include cracks and breakage of the glass plate due to vertical cracks in the glass ribbon after cutting in the cutting process.

In this way, cracks and breakage, which are defects different from the above-mentioned shape defects and partial breakage, can be detected from a thermal image showing the temperature distribution of the glass sheet by thermography. This crack and breakage occurs along with a vertical crack in the glass ribbon after cutting. Here, a vertical crack means a crack that is formed along the vertical direction of the glass ribbon and that breaks the entire glass ribbon over time. When this vertical crack occurs, a larger crack than the above-mentioned partial breakage occurs in the glass sheet cut from the glass ribbon, and it may become impossible to cut out the glass sheet. According to the configuration here, the occurrence of such vertical cracks in the glass ribbon can be detected from a thermal image of the glass sheet, not the glass ribbon.

In this method, the area of at least a portion of the glass plate may be calculated from the temperature distribution of the glass plate, and the crack or breakage may be detected based on the area and a second threshold value.

In this way, the cracks and damage caused by the vertical cracks described above are detected based on the area of the glass plate and the second threshold value, making it possible to detect them accurately with little error. In this case, in the thermal image showing the temperature distribution by thermography, a low-temperature drawing corresponding to the cracks and damage appears in a part of the area where a high-temperature drawing should be made due to the presence of the glass plate. Note that the cracks and damage also include damage in which the glass plate no longer exists, in which case the high-temperature areas indicating the presence of the glass plate disappear on the thermal image. Under such circumstances, the area of the high-temperature areas (which may be zero) is obtained, and the cracks and damage are detected based on this area and the second threshold value. The area of the glass plate in this case is, as in the case described above, for example, the area of a part or the entire area of the glass plate, and can be obtained by the number of pixels in the thermal image. The second threshold value here is set to, for example, 30% to 50% of the area of the glass plate when there are no defects (the area corresponding to the above-mentioned area). Therefore, if the area of the high-temperature areas in the thermal image exceeds the second threshold value, it is determined not to be a crack or damage, and if it is equal to or less than the second threshold value, it is detected as a crack or damage. In addition, since the second threshold value is a numerical value smaller than the first threshold value described above, the partial damage described above is detected as a defect when it is equal to or smaller than the first threshold value and exceeds the second threshold value.

In this method, if the crack or breakage is detected, it may be determined that a vertical crack has occurred in the glass ribbon, and the cutting device used to carry out the cutting process may be retracted.

In this way, when a crack or breakage of the glass sheet is detected, it is assumed that a vertical crack has occurred in the glass ribbon, and appropriate measures can be taken against this vertical crack. As described above in detail, the crack or breakage of the glass sheet occurs along with a vertical crack in the glass ribbon. Therefore, if the occurrence of a crack or breakage of the glass sheet is detected, the occurrence of a vertical crack in the glass ribbon is also detected. In other words, the occurrence of a crack or breakage of the glass sheet is assumed to be the occurrence of a vertical crack in the glass ribbon. The condition (for example, the second threshold value described above) that serves as the standard for determining whether or not the crack or breakage is a crack is set as a condition that satisfies such an event. From this perspective, according to the configuration here, when a crack or breakage of the glass sheet is detected, that is, when it is assumed that a vertical crack has occurred in the glass ribbon, the cutting device can be evacuated early. This makes it possible to prevent contamination or failure of the cutting device caused by a large amount of glass fragments or glass powder scattering and falling from the glass ribbon due to the occurrence of a vertical crack.

In these methods, the thermograph may measure the temperature distribution of the measurement object from diagonally below.

In this way, when the area that can be measured by the thermograph is only a part of the area of the measurement object (for example, if the measurement object is a glass plate, then a part of the area in the vertical direction of the glass plate), the following advantages can be obtained. That is, when the measurement is performed by the thermograph from diagonally below, the area in which the measurement object can be measured is longer in the vertical direction than the area in which the measurement object can be measured when the measurement is performed along the horizontal direction. Therefore, the advantage of being able to detect defects occurring in a wide measurement area is obtained. In addition, the following advantages can be obtained. That is, when the measurement is performed by the thermograph along the horizontal direction or from diagonally above, it is necessary to install the thermograph at a relatively higher position than when it is performed from diagonally below. In such a case, there is a risk that the thermograph will interfere with peripheral devices (such as a device for forming a scribe line) arranged around the cutting position of the glass ribbon, and the degree of freedom in the installation space of the thermograph will decrease. According to the configuration here, the thermograph can be installed at a relatively lower position compared to the above-mentioned cases of performing the measurement from the horizontal direction or from diagonally above. This makes it less likely that the thermography will interfere with the peripheral devices described above, and increases the freedom in the installation space for the thermography.

In these methods, the thermograph may be capable of being adjusted in the vertical direction so as to point toward the surface of the object to be measured.

In this way, it is possible to appropriately deal with adverse effects that may occur when the size, thickness, variety, etc. of the glass ribbon to be formed and transported is changed, or when the measurement target is shaken even if this change is not made. That is, when such a change or shake occurs, the position of the measurement target after cutting may shift in the vertical direction. When such a position shift occurs, not only does the detection accuracy of defects occurring in the measurement target decrease, but in some cases, a part or all of the measurement target may deviate in the vertical direction from the area that can be measured by the thermography, making it impossible to detect the defect. According to the configuration here, by adjusting the direction of the thermography (the direction in which it is directed toward the surface of the measurement target) in the vertical direction, the area that can be measured by the thermography can be shifted in response to the vertical shift of the measurement target. As a result, the area in which the measurement target can be measured is appropriately corrected, and further high accuracy in detecting defects is achieved.

In these methods, the thermograph may be capable of adjusting the direction in which it points toward the surface of the object to be measured in the width direction.

In this way, even if the size, thickness, variety, etc. of the glass ribbon is changed as described above, or the measurement object vibrates, causing the measurement object to shift in the width direction after cutting, the area in which the measurement object can be measured can be appropriately corrected by adjusting the orientation of the thermograph in the width direction.

In these methods, the thermography may be capable of adjusting its position in the vertical direction.

In this way, even if the size, thickness, or type of the glass ribbon is changed as described above, or the measurement target is swayed, causing the measurement target to shift vertically after cutting, the area in which the measurement target can be measured can be appropriately corrected by adjusting the vertical position of the thermograph. In this case, the area in which the measurement target can be measured can be shifted vertically without changing the orientation of the thermograph or by changing its orientation.

In these methods, the height position of the upper edge of the glass plate after cutting is detected on a thermal image obtained by measuring the temperature distribution using the thermograph, and this detected height position is used as the origin position in the vertical direction to set a defect inspection area covering the upper end of the glass plate and the space above it, and defects occurring in the glass plate are detected by image analysis within the defect inspection area.

In this way, the defect inspection area is set at an appropriate position on the thermal image of the thermograph, so that defects occurring on the glass plate can be detected with even higher accuracy. More specifically, the vertical position of the glass plate depicted in the thermal image is not uniformly determined. This is due not only to the changes and vibrations as described above, but also to the fact that the timing at which the thermograph captures the thermal image fluctuates each time a measurement is performed. Under such circumstances, when the defect inspection area is set on the thermal image, there is a risk that the vertical position of the defect inspection area will vary or be subject to error, which may lead to erroneous detection of defects occurring on the glass plate. According to the configuration here, the height position of the upper edge of the glass plate depicted in the thermal image is detected, and the defect inspection area is set with this detected height position as the vertical origin position, so that the vertical position of the defect inspection area relative to the glass plate on the thermal image is uniformly determined. This makes it less likely that erroneous detection will occur when detecting defects occurring on the glass plate by image analysis within the defect inspection area, and the accuracy of defect detection can be improved even more reliably.

A second aspect of the present invention, which has been devised to solve the above problems, is a glass sheet manufacturing apparatus comprising a forming zone for forming a glass ribbon, a conveying device for conveying the glass ribbon along the longitudinal direction, and a cutting device for cutting the glass ribbon along the width direction to cut out glass sheets, characterized in that the apparatus comprises a detection device for measuring the temperature of the measurement object, which is either the cut end of the glass ribbon after cutting by the cutting device, a glass sheet, or either one of the two, and detecting defects occurring in the measurement object based on the measurement results.

This allows the same effects to be obtained as the previously described manufacturing method, which has substantially the same configuration as this manufacturing apparatus.

According to the present invention, the cut side end of the glass ribbon after cutting, the glass plate, or either one of them can be measured, and defects occurring in the measurement object can be detected with high accuracy.

1 is a vertical sectional side view showing an overall configuration of a glass sheet manufacturing apparatus according to an embodiment of the present invention. 2 is a schematic front view showing a main part of the glass sheet manufacturing apparatus as viewed from a direction A in FIG. 1 . FIG. 2 is a front view showing a schematic state immediately after a glass ribbon is cut using the glass sheet manufacturing apparatus according to the embodiment of the present invention. FIG. 2 is an exaggerated front view showing the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is an exaggerated front view showing the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is an exaggerated front view showing the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is an exaggerated front view showing the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is an exaggerated front view showing the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is an exaggerated front view showing the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is an exaggerated front view showing the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 1 is a schematic front view for explaining a method for detecting a first example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 11 is a schematic front view for explaining a method for detecting a second example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 11 is a front view showing a method for detecting a third example of defects in a glass sheet and a glass ribbon from a thermal image of temperature distribution obtained by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 11 is a schematic front view for explaining another method for detecting a first example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 11 is a schematic front view for explaining another method for detecting a second example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 11 is a schematic front view for explaining another method for detecting a third example of defects in a glass sheet and a glass ribbon from a thermal image of temperature distribution by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 11 is a front view showing a method for detecting a fourth example of defects in a glass sheet and a glass ribbon from a thermal image of temperature distribution obtained by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 11 is a front view showing a method for detecting a fifth example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution obtained by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic front view of a glass sheet manufacturing apparatus according to a modified example of an embodiment of the present invention, as viewed from a direction A in FIG. 1 . FIG. 11 is a schematic front view showing a range that can be measured by a thermograph that is a component of a glass sheet manufacturing apparatus according to a modified example of an embodiment of the present invention. 1 is a schematic side view showing a relationship between a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention, and a glass sheet. FIG. FIG. 2 is a schematic side view showing a range in which a glass sheet can be measured by a thermograph, which is a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention. 1 is a schematic side view showing a relationship between a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention, and a glass sheet. FIG. FIG. 2 is a schematic plan view showing a relationship between a thermograph, which is a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention, and a glass sheet. 1 is a schematic side view showing a relationship between a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention, and a glass sheet. FIG. FIG. 1 is a front view showing a method for setting a defect inspection area on a thermal image of temperature distribution obtained by a thermograph, which is a component of the glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 1 is a front view showing a method for setting a defect inspection area on a thermal image of temperature distribution obtained by a thermograph, which is a component of the glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 1 is a front view showing a first example of a method for detecting defects by image analysis within a defect inspection area set on a thermal image of temperature distribution by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 11 is a front view showing a second example of a method for detecting defects by image analysis within a defect inspection area set on a thermal image of temperature distribution by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention.

One embodiment of the present invention is described below with reference to the attached drawings.

Figure 1 is a vertical cross-sectional side view showing the overall configuration of a glass sheet manufacturing apparatus according to this embodiment. As shown in the figure, the glass sheet manufacturing apparatus includes a processing device 1 for processing glass ribbon G, a cutting device 2, and a detection device 3.

The processing device 1 includes a forming zone 11 for continuously forming the glass ribbon G, a heat treatment zone 12 for heat treating (slowly cooling) the glass ribbon G, a cooling zone 13 for cooling the glass ribbon G to near room temperature, and a conveying device 14 consisting of roller pairs R arranged in multiple stages above and below in each of the forming zone 11, the heat treatment zone 12 and the cooling zone 13.

The forming zone 11 and the heat treatment zone 12 are constituted by a furnace in which the transport path of the glass ribbon G is surrounded by walls, and heating devices such as heaters for adjusting the temperature of the glass ribbon G are arranged at appropriate locations within the furnace. On the other hand, the cooling zone 13 is open to the outside atmosphere at room temperature, with the transport path of the glass ribbon G not surrounded by walls, and no heating devices such as heaters are arranged therein.

In the internal space of the forming zone 11, a forming body 15 is disposed, which forms a glass ribbon G from molten glass Gm by the overflow downdraw method. The molten glass Gm supplied to the forming body 15 overflows from a groove (not shown) formed in the top 15a of the forming body 15. This overflowing molten glass Gm flows along both side surfaces 15b, which have a wedge-shaped cross section, of the forming body 15 and joins at the bottom end. This allows a plate-shaped glass ribbon G to be continuously formed. This continuously formed glass ribbon G is sent downward in a vertical position (preferably a vertical position).

The internal space of the heat treatment zone 12 has a predetermined temperature gradient downward. The glass ribbon G in the vertical position is heat treated (slowly cooled) so that its temperature decreases as it moves downward through the internal space of the heat treatment zone 12. This heat treatment reduces internal distortion of the glass ribbon G. The temperature gradient in the internal space of the heat treatment zone 12 is adjusted, for example, by a heating device installed on the inner wall surface of the heat treatment zone 12.

The multiple roller pairs R constituting the conveying device 14 clamp both widthwise ends of the glass ribbon G in a vertical position from both the front and back. The uppermost roller pair R arranged in the forming zone 11 is a cooling roller. Note that, in the internal space of the heat treatment zone 12, the multiple roller pairs R may include ones that do not clamp the side ends of the glass ribbon G. In other words, the distance between the roller pairs R may be made larger than the thickness of both widthwise ends of the glass ribbon G, and the glass ribbon G may pass between the roller pairs R.

In this embodiment, both widthwise ends of the glass ribbon G produced by the processing device 1 have portions (hereinafter also referred to as "ear portions") that are thicker than the widthwise central portion due to the effects of shrinkage during the molding process, etc.

The cutting device 2 is configured to sequentially cut out glass plates from the glass ribbon G by cutting the glass ribbon G in a vertical position at predetermined lengths in the width direction below the processing device 1. The glass plates become glass original plates (mother glass plates) from which one or more product glass plates are obtained in a later process by removing the edge portions. Here, the width direction is a direction perpendicular to the longitudinal direction (transport direction) of the glass ribbon G, and in this embodiment, it substantially coincides with the horizontal direction.

As shown in Figures 1 and 2, the cutting device 2 includes a scribe line forming device 21 and a breakage device 22.

The scribe line forming device 21 is a device that forms a scribe line S on the first main surface of the glass ribbon G in a vertical position that has been lowered from the processing device 1 at the scribe line forming position P1. In this embodiment, the scribe line forming device 21 includes a wheel cutter 23 that forms a scribe line S on the first main surface of the glass ribbon G along its width direction, and a support member 24 (e.g., a support bar or a support roller) that supports the second main surface of the glass ribbon G (the surface opposite the first main surface) at a position corresponding to the wheel cutter 23.

The wheel cutter 23 and the support member 24 are configured to follow the glass ribbon G as it descends, forming a scribe line S across the entire width or a portion of the width of the glass ribbon G. In this embodiment, the scribe line S is also formed on the relatively thick ear portion. The scribe line S may also be formed by irradiating a laser, etc.

The slicing device 22 is a device that slicing the glass ribbon G along the scribe line S at a slicing position (cutting position) P2 provided below the scribe line formation position P1 to cut out a glass sheet. In this embodiment, the slicing device 22 includes a slicing member 25 that contacts the area where the scribe line S is formed from the second main surface side, and a gripping mechanism 26 that grips the lower area of the glass ribbon G below the slicing position P2.

The splitting member 25 is composed of a plate-like body (base plate) having a flat surface that contacts the entire or part of the width of the glass ribbon G while descending to follow the descending glass ribbon G. The contact surface of the splitting member 25 may be a curved surface that is curved in the width direction.

The gripping mechanism 26 includes chucks 27 arranged at multiple locations in the vertical direction at both ends of the width of the glass ribbon G, and arms 28 (see FIG. 2) that hold the multiple chucks 27 at both ends of the width. These arms 28 perform an operation (operation in the direction B) to bend the glass ribbon G with the bending member 25 as a fulcrum while lowering the multiple chucks 27 following the glass ribbon G that is descending. This applies bending stress to the scribe line S and its vicinity, and the glass ribbon G is bent and broken in the width direction along the scribe line S. As a result of cutting by this bending, a glass plate is cut out from the glass ribbon G. The chucks 27 may be changed to another holding form, such as holding the glass ribbon G by negative pressure adsorption.

As shown in Figures 1 and 3, the detection device 3 is a device for detecting defects occurring in the cut end Gt of the glass ribbon G and the glass sheet g after being cut by the cutting device 2, by measuring the cut end Gt and the glass sheet g. In this embodiment, the detection device 3 includes a thermograph 31, a detection unit 32, a control unit 33, and an alarm unit 34. Here, the glass ribbon G and the glass sheet g have a widthwise length of 1000 to 3500 mm and a thickness of 100 to 2000 μm. In addition, the glass sheet g has a vertical length (vertical length) of 800 to 3000 mm.

The thermograph 31 measures the temperature distribution of the measurement objects Gt, g, and is disposed below the height position of the wheel cutter 23 and above the lower end of the gripping mechanism 26. The thermograph 31 of this embodiment is disposed below the height position of the cleavage member 25 and above the lower end of the gripping mechanism 26. The thermograph 31 is disposed at the widthwise center position of the measurement objects Gt, g, on one of the main surfaces of the measurement objects Gt, g (the first main surface side of the glass ribbon G) and spaced apart from the main surface. The distance from the measurement objects Gt, g of the thermograph 31 can be set arbitrarily within a range in which the temperature distribution of the measurement objects Gt, g can be measured without contact (for example, in the range of 800 to 3000 mm). The thermograph 31 may be disposed on the other main surface side of the measurement objects Gt, g.

The detection unit 32 performs image analysis on the thermal image showing the temperature distribution by the thermograph 31, and detects defects occurring in the measurement objects g and Gt based on the results. The detection unit 32 is composed of, for example, a personal computer. Here, when the glass ribbon G is cut by folding, not only does the glass ribbon G after cutting shake, but the glass sheet g also shakes due to the vibration and shaking of the gripping mechanism 26. In addition, when the glass ribbon G is thin or when the glass ribbon G is warped, the shaking of the glass ribbon G and the glass sheet g after cutting may become noticeable. However, since the detection unit 32 detects defects occurring in the measurement objects g and Gt from the temperature distribution by the thermograph 31, it is less likely to be adversely affected by the shaking of the glass ribbon G and the glass sheet g.

When a defect is detected by the detection unit 32, the control unit 33 issues a control signal to cause the chuck 27 of the gripping mechanism 26 to perform gripping and release operations, and to move the cutting device 2 to a retreat position and a return position, etc.

The alarm unit 34 issues an alarm when the detection unit 32 detects a specific defect (for example, cracks or breakage g4 of the glass sheet g associated with vertical cracks G4 of the glass ribbon G, which will be described later). The alarm is notified to the worker by voice, display, or the like. The alarm unit 34 may be omitted.

Figures 4a to 8 show examples of defects that can be detected by the detection unit 32. Note that, for convenience, the gripping mechanism 26 and other components are not shown in each of these figures.

In the glass sheet g shown in FIG. 4a, a shape defect occurs on the upper cut surface ga due to a horn (commonly known as) g1, in which the middle part in the width direction protrudes upward. The horn g1 is, for example, several mm high and several mm wide. Due to this, a shape defect occurs on the lower cut surface Ga of the glass ribbon G shown in the same figure due to a chip G2 in which the middle part in the width direction is recessed upward. Conversely, in the glass sheet g shown in FIG. 4b, a shape defect occurs on the upper cut surface ga due to a chip g2 in which the middle part in the width direction is recessed downward. The chip g2 is, for example, several mm deep and several mm wide. Due to this, a shape defect occurs on the lower cut surface Ga of the glass ribbon G shown in the same figure due to a horn G1 in which the middle part in the width direction protrudes downward.

In the glass sheet g shown in FIG. 5a, a shape defect occurs on the upper cut surface ga due to a horn g1 in which one end in the width direction protrudes upward. The horn g1 is, for example, several mm high and several mm wide. Due to this, a shape defect occurs on the lower cut surface Ga of the glass ribbon G shown in the same figure due to a chip G2 in which one end in the width direction is missing. Such shape defects of the cut surfaces ga, Ga occur due to the ears being relatively thick. Conversely, in the glass sheet g shown in FIG. 5b, a shape defect occurs on the upper cut surface ga due to a chip g2 in which one end in the width direction is missing. Due to this, a shape defect occurs on the lower cut surface Ga of the glass ribbon G shown in the same figure due to a horn G1 in which one end in the width direction protrudes downward. Such shape defects of the cut surfaces ga, Ga also occur due to the ears being relatively thick.

The glass plate g shown in Figure 6 has a wavy shape defect over the entire upper cut surface ga. As a result, a wavy shape defect also occurs over the entire lower cut surface Ga of the glass ribbon G shown in the same figure. Such shape defects occur when cracks deviate from the scribe line and propagate. In addition, shape defects caused by cracks deviating from the scribe line and propagating may cause part of the cut surface ga to have a wavy shape, or part or all of the cut surface ga to have a bow shape.

In the examples shown in Figures 4a to 6, the irregularities due to shape defects in the glass plate g and the irregularities due to shape defects in the glass ribbon G are in an opposite relationship at the same position in the width direction, but this relationship does not have to be the case.

The glass plate g shown in Figure 7 has one partial break g3 originating from the upper cut surface ga. The partial break g3 is, for example, 3-500 mm deep and 10-2000 mm wide, and is larger than the chip g2 mentioned above. There may be more than one partial break g3. Such partial break g3 occurs when a part of the glass plate g (the area around the upper cut surface ga or the middle part in the width direction) breaks during cutting.

In the glass sheet g shown in FIG. 8, a crack g4 has occurred at one location due to a vertical crack G4 in the glass ribbon G. This crack g4 is caused by a vertical crack G4 in the glass ribbon G caused by the crack propagating in the vertical direction. The vertical crack G4 may lead to damage to the entire glass ribbon G over time. Therefore, the crack g4 in the glass sheet g caused by the vertical crack G4 in the glass ribbon G tends to become larger in the subsequent glass sheets g, and may ultimately make it impossible to cut out the glass sheet g from the glass ribbon G.

Figures 9 to 16 are thermal images F1 to F5 showing the temperature distribution measured by the thermograph 31, and these thermal images F1 to F5 show the measurement objects g and Gt having defects. For convenience, Figures 9 to 14 only show the main parts of the measured thermal images. Here, the temperature of the measurement objects g and Gt is, for example, less than 100°C, and preferably less than 80°C. In addition, the temperature of the measurement objects g and Gt is higher than the temperature of the surrounding spatial region Z. Therefore, in the thermal images F1 to F5, the glass plate g and glass ribbon G are depicted in light colors, and the surrounding spatial region Z is depicted in dark colors.

The thermal images F1 to F3 shown in Figures 9 to 11 show the shapes of the cut surfaces ga, Ga of the measurement objects g, G. The detection unit 32 obtains the distribution of the height positions of the cut surfaces ga, Ga from these thermal images F1 to F3, and detects whether or not there is a shape defect in the cut surfaces ga, Ga based on the height (here, the height difference). The specific method is described below.

The thermal image F1 shown in FIG. 9 shows the measurement objects g and Gt having the defects shown in FIG. 4a. Here, a method for the detection unit 32 to detect the shape defect caused by the horn g1 generated on the upper cut surface ga of the glass plate g from this thermal image F1 will be described. First, in the area (relatively bright area) where the glass plate g is drawn on this thermal image F1, a basic straight line K1 parallel to the straight line K0 is set at a position a predetermined distance away from the straight line K0 where the scribe line S was formed. Next, the maximum and minimum values of the distance from this straight line K1 to the upper contour line of the area where the glass plate g is drawn are obtained. In the illustrated example, the distance (maximum value) Ma from the straight line K1 to the top gx of the horn g1 and the distance (minimum value) Mi from the straight line K1 to the straight line K0 are obtained. Then, the difference ΔM between the maximum value Ma and the minimum value Mi is calculated, and the detection unit 32 detects a shape defect occurring on the upper cut surface ga of the glass sheet g based on this difference ΔM and a threshold value. Specifically, when the difference ΔM is equal to or less than the threshold value, the detection unit 32 determines that there is no shape defect, and when the difference ΔM exceeds the threshold value, the detection unit 32 detects that there is a shape defect in the glass sheet g. Here, since the difference ΔM exceeds the threshold value, the detection unit 32 detects that there is a shape defect in the glass sheet g. Note that even when a horn g1 occurs on the upper cut surface ga of the glass sheet g in the manner shown in FIG. 5a, the detection unit 32 detects the presence or absence of a shape defect occurring in the glass sheet g in the same manner as described here.

The thermal image F2 shown in FIG. 10 shows the measurement objects g and Gt having the defects shown in FIG. 4b. Here, a method for the detection unit 32 to detect the shape defect caused by the chip g2 generated on the upper cut surface ga of the glass plate g from this thermal image F2 will be described. For this thermal image F2, a straight line K1 is set at the same position as above, and the maximum and minimum values of the distance from this straight line K1 to the upper contour line of the area in which the glass plate g is drawn are obtained. In the illustrated example, the distance (minimum value) Mi from the straight line K1 to the lowest part gy of the chip g2 and the distance (maximum value) Ma from the straight line K1 to the straight line K0 are obtained. Then, when the difference ΔM between the maximum value Ma and the minimum value Mi is equal to or less than a threshold value, the detection unit 32 determines that the shape is not defective, and when the difference ΔM exceeds the threshold value, it detects that the shape is defective. Here, since the difference ΔM exceeds the threshold value, the detection unit 32 detects that the shape defect has occurred in the glass plate g. In addition, even if a chip g2 occurs on the upper cut surface ga of the glass plate g in the manner shown in Figure 5b, the detection unit 32 detects whether or not the shape is defective using a method similar to that described here.

The thermal image F3 shown in FIG. 11 shows the measurement objects g and Gt having defects of the type shown in FIG. 6 described above. Here, a method in which the detection unit 32 detects shape defects due to the wavy shape generated on the upper cut surface ga of the glass plate g from this thermal image F3 will be described. For this thermal image F3, a straight line K1 is set at the same position as above, and the maximum and minimum values of the distance from this straight line K1 to the upper contour line of the area in which the glass plate g is drawn are obtained. In the illustrated example, the distance (maximum value) Ma from the straight line K1 to the top gz of the highest mountain among the multiple mountains, and the distance (minimum value) Mi from the straight line K1 to the lowest part gZ of the lowest valley among the multiple valleys are obtained. Then, when the difference ΔM between the maximum value Ma and the minimum value Mi is equal to or less than a threshold value, the detection unit 32 determines that there is no shape defect, and when the difference ΔM exceeds the threshold value, it detects that there is a shape defect. Here, since the difference ΔM exceeds the threshold value, the detection unit 32 detects that there is a shape defect in the glass plate g.

The shape defect caused by the chip G2 on the lower cut surface Ga of the glass ribbon G in the thermal image F1 shown in FIG. 9 can be detected by substantially the same method as the detection of the shape defect caused by the chip g2 on the thermal image F2 shown in FIG. 10. The shape defect caused by the horn G1 on the lower cut surface Ga of the glass ribbon G in the thermal image F2 shown in FIG. 10 can be detected by substantially the same method as the detection of the shape defect caused by the horn g1 on the thermal image F1 shown in FIG. 9. Furthermore, the shape defect caused by the wave shape on the lower cut surface Ga of the glass ribbon G in the thermal image F3 shown in FIG. 11 can be detected by substantially the same method as the detection of the shape defect caused by the wave shape of the glass sheet g on the thermal image F3 shown in the same figure. Note that the substantially same method means that the method itself is the same, except that the top and bottom relationships are reversed.

In this case, when the detection unit 32 detects that the glass sheet g has a shape defect from the thermal images F1 to F3 illustrated in Figs. 9 to 11, the gripping operation by the chuck 27 of the gripping mechanism 26 is released based on a control signal from the control unit 33, and the glass sheet g is discarded. The discarded glass sheet g is collected. Here, the glass sheet g after cutting is often gripped at the upper part and transported to a subsequent process. Therefore, if the glass sheet g with a shape defect on the upper cut surface ga is discarded, it is possible to prevent the glass sheet g from being damaged when the upper part is gripped and transported, and the associated contamination of the production line. In addition, since the shape defect on the upper cut surface ga of the glass sheet g is likely to occur due to wear and tear of the wheel cutter 23, it is preferable to replace the wheel cutter 23 when the detection unit 32 detects that the shape defect has occurred. In this way, it is possible to prevent the subsequent glass sheets g from having a shape defect.

9 to 11, the maximum value Ma, minimum value Mi, and difference ΔM are obtained based on the straight lines K0 and K1, but the maximum value Ma, minimum value Mi, and difference ΔM may be obtained without using the straight lines K0 and K1. Specifically, the upper contour line of the glass plate g may be obtained from the thermal image, and the height of the point on the contour line where the height position is the maximum value Ma and the height of the point on the contour line where the height position is the minimum value Mi, and the difference ΔM may be obtained from these.

Figures 12 to 14 respectively illustrate other methods for detecting defects in the shape of the glass sheet g from the thermal images F1 to F3 shown in Figures 9 to 11 above. These other methods also involve the detection unit 32 determining the distribution of height positions of the cut surfaces ga, Ga from the thermal images F1 to F3, and detecting defects in the shape of the cut surfaces ga, Ga based on the height.

In the method illustrated in FIG. 12, first, on the thermal image F1, measurement lines L1 and L2 are drawn above and below the line L0 on which the regular cutting line of the glass plate g, that is, the scribe line S, was formed. These two measurement lines L1 and L2 are parallel to the line L0 and are spaced the same distance from the line L0. Then, it is measured whether there is a place on the upper measurement line L1 where the brightness is higher than the preset value, that is, whether there is a place where the temperature is higher than the preset temperature. It is also measured whether there is a place on the lower measurement line L2 where the brightness is higher than the preset value (whether there is a place where the temperature is higher than the preset value). In this case, the range in which the brightness (temperature) is measured is the entire range in the width direction of the glass plate g on the measurement lines L1 and L2. In the thermal image F1, there is one location on the upper measurement line L1 where the brightness (temperature) is higher than the set value, and the brightness (temperature) is higher than the set value in the entire area on the lower measurement line L2. The detection unit 32 recognizes this state and detects that a shape defect has occurred in the glass sheet g. The detection unit 32 also detects whether or not a horn g1 generated on the upper cut surface ga of the glass sheet g in the manner shown in Figure 5a is a shape defect in the same manner as described here.

In the method illustrated in FIG. 13, similarly to the above-mentioned case, measurement lines L1 and L2 are drawn above and below the line L0 on the thermal image F2, and the brightness (temperature) on the upper measurement line L1 and the brightness (temperature) on the lower measurement line L2 are measured. In this thermal image F2, the brightness (temperature) is lower than the set value in the entire area on the upper measurement line L1, and there is one location on the lower measurement line L2 where the brightness (temperature) is lower than the set value. By recognizing such a state, the detection unit 32 detects that a shape defect has occurred in the glass sheet g. In addition, the detection unit 32 detects whether or not a chip g2 that has occurred on the upper cut surface ga of the glass sheet g in the manner shown in FIG. 5b is a shape defect in the same manner as described here.

14, in the same manner as described above, measurement lines L1, L2 are drawn above and below line L0 on thermal image F3, and the brightness (temperature) on the upper measurement line L1 and the brightness (temperature) on the lower measurement line L2 are measured. In this thermal image F3, there are multiple points (two in the example) on the upper measurement line L1 where the brightness (temperature) is higher than the set value, and the brightness (temperature) is higher than the set value over the entire area on the lower measurement line L2. By recognizing this state, the detection unit 32 detects that a shape defect has occurred in the glass sheet g.

15 and 16 show thermal images F4 and F5 in which the entire area of the glass sheet g and the cut end Gt of the glass ribbon G are shown. From these thermal images F4 and F5, the detection unit 32 calculates the areas of the measurement objects g and Gt, and detects defects that have occurred in the measurement objects g and G based on the areas and a threshold value. The specific method is described below.

The thermal image F4 shown in FIG. 15 shows the measurement objects g and Gt having the defects shown in FIG. 7. Here, the method of the detection unit 32 detecting the partial damage g3 that has occurred in the glass plate g from this thermal image F4 will be described. First, the area of the glass plate g is obtained from the number of pixels on this thermal image F4. In this case, the area of the glass plate g that is held by the chuck 27 may be lower in temperature than the area that is not held, and may be depicted in a dark color similar to that of the spatial area Z. In this case, the area of the area where the main surface of the glass plate g is exposed is obtained. Note that, when the area of the glass plate g that is held by the chuck 27 and the area that is not held have the same temperature and are both depicted in a light color, the area of the entire area of the glass plate g is obtained. If this area exceeds the first threshold, the detection unit 32 determines that the partial damage g3 is not present, and if this area is equal to or less than the first threshold and exceeds a second threshold described later, the detection unit 32 detects the partial damage g3. The first threshold value is, for example, 90% to 99% of the area of the glass sheet g in a state where no defects have occurred (the area corresponding to the above region). In this case, since the above area is equal to or smaller than the first threshold value and exceeds the second threshold value, the detection unit 32 detects that partial damage g3 has occurred in the glass sheet g.

In this case, when the detection unit 32 detects that partial damage g3 has occurred in the glass sheet g from the thermal image F4 illustrated in FIG. 15, the gripping action by the chuck 27 of the gripping mechanism 26 is released based on a control signal from the control unit 33, and the glass sheet g is discarded. The discarded glass sheet g is collected. This makes it less likely that the glass sheet g having partial damage g3 will be mistakenly transported to a subsequent process and subjected to subsequent processing. In addition, since partial damage g3 of the glass sheet g is likely to occur when the warp of the glass ribbon G is large, when the detection unit 32 detects that this partial damage g3 has occurred, it is preferable to take measures to reduce the warp of the glass ribbon G. In this way, partial damage g3 can be prevented from occurring in the subsequent glass sheet g.

The thermal image F5 shown in FIG. 16 shows the measurement objects g and Gt having defects of the type shown in FIG. 8 described above. Here, a method for the detection unit 32 to detect cracks and damage g4 associated with vertical cracks G4 in the glass ribbon G from this thermal image F5 will be described. First, the area of the glass plate g is obtained from the number of pixels on this thermal image F5. The relationship between the area of this glass plate g and the chuck 27 is the same as in the case described above. If this area exceeds the second threshold, the detection unit 32 determines that it is not cracked or damaged g4, and if this area is equal to or less than the second threshold, the detection unit 32 detects it as cracked or damaged g4. The second threshold is, for example, 30% to 50% of the area of the glass plate g in a state where no defects have occurred (the area corresponding to the above region). Here, since the above area is equal to or less than the second threshold, the detection unit 32 detects that cracks and damage g4 have occurred in the glass plate g. In this case, as described above, the crack or breakage g4 of the glass sheet g occurs in conjunction with the vertical crack G4 of the glass ribbon G. Therefore, when the detection unit 32 detects that the crack or breakage g4 has occurred in the glass sheet g, the detection unit 32 also detects that the vertical crack G4 has occurred in the glass ribbon G. In other words, the occurrence of the crack or breakage g4 of the glass sheet g is regarded as the occurrence of the vertical crack G4 in the glass ribbon G. The second threshold value is set as a value that satisfies such circumstances.

In this case, if the thermal image F5 illustrated in FIG. 16 detects that a crack or breakage g4 has occurred in the glass sheet g, it is assumed that a vertical crack G4 has occurred in the glass ribbon G, and the cutting device 2 moves to the evacuation position based on a control signal from the control unit 33. This evacuation position is a position where glass fragments and glass powder from the glass ribbon G will not fall onto the cutting device 2. At the evacuation position, glass fragments and the like adhering to the cutting device 2 are removed by cleaning. This makes it possible to prevent the glass ribbon G or glass sheet g from being damaged by glass fragments and glass powder remaining in the cutting device 2 when the forming of the glass ribbon G is resumed and the cutting device 2 is returned to its original position.

This glass sheet manufacturing device detects defects occurring in the measurement objects g and Gt based on the measurement results of the measurement objects g and Gt, and although it cannot recognize the type of defect, it may be configured to recognize defects by type. In this case, post-processing can be performed by subdividing the defects by type.

With a glass plate manufacturing apparatus having the above-mentioned configuration, defects occurring in the measurement objects g and Gt can be detected with high accuracy, but in order to achieve even higher accuracy in detecting defects, the configuration shown below may be adopted.

In the first configuration, as shown in Figure 17, multiple thermographs 31 (three in the illustrated example) are installed along the width direction. These thermographs 31 are arranged at equal intervals in the width direction and installed at the same height position. This height position is the same as the height position when a single thermograph 31 is installed as described above. In addition, the distance and spacing of these thermographs 31 from the measurement targets Gt, g are also the same as the distance and spacing of the single thermograph 31 when the previously described single thermograph 31 is installed.

In the measurement of the temperature distribution by these thermographs 31, multiple thermal images (three in this embodiment) are obtained. More specifically, as shown in FIG. 18, the regions 35 in which the multiple thermographs 31 can measure the measurement objects g and Gt are lined up in a row in the width direction. These regions 35 overlap with adjacent regions 35 (the overlapping portions are indicated by the reference numerals 35x) and cover the entire width direction of the measurement objects g and Gt. Therefore, multiple thermal images are also obtained by imaging the measurement objects g and Gt in a similar manner to the measurable regions 35 and 35x. That is, the multiple thermal images are obtained by partially overlapping adjacent thermal images and by imaging the entire width direction of the measurement objects g and Gt. This allows defects occurring in the measurement objects g and Gt to be detected without omission by the thermal images taken by the multiple thermographs 31. Then, when a defect in the cut-side end Gt of the glass sheet g or the glass ribbon G is detected by any one of the thermal images of the multiple thermographs 31, the cut-side end Gt of the glass sheet g or the glass ribbon G is deemed to be defective. On the other hand, when a defect in the cut-side end Gt of the glass sheet g or the glass ribbon G is not detected by all the thermal images, the cut-side end Gt of the glass sheet g or the glass ribbon G is deemed not to be defective. In this case, an anti-reflection member (not shown) is arranged by pasting or the like on the front part of each thermograph 31. If this anti-reflection member is not arranged, it may cause a decrease in detection accuracy when detecting defects using each thermograph 31 due to reflected light from lighting, etc. According to the configuration here, the presence of the anti-reflection member makes it difficult to be adversely affected by reflected light from lighting, etc.

In a second configuration, as shown in Figure 19, each thermograph 31 is installed so as to measure the temperature distribution of the measurement objects g and Gt from diagonally below. In the illustrated example, the lower end Gt of the glass ribbon G is omitted (the same applies to Figures 20 to 23 described below). In this case, the angle α between the direction C in which each thermograph 31 points toward the surface of the glass plate g and the horizontal direction is 3° to 80° (preferably, the lower limit is 30° and the upper limit is 60°).

This second configuration provides the following advantages when the glass sheet g is in a vertical position, that is, in the vertical position shown by the solid line in the figure or in the nearly vertical position shown by the dashed line in the figure (e.g., an inclined position with an angle β of 15° or less with respect to the vertical direction). That is, as shown in Figure 20, the area 35 in which the glass sheet g can be measured when the measurement is performed with the thermograph 31 from diagonally below is longer in the vertical direction than the area 35a in which the glass sheet g can be measured when the measurement is performed horizontally. Therefore, defects occurring in the glass sheet g can be detected in a wide measurement area.

Furthermore, this second configuration also provides the following advantages. That is, when the measurement using the thermograph 31 is performed along the horizontal direction or from diagonally above, the thermograph 31 needs to be installed at a relatively higher position (for example, the area indicated by the symbol H in FIG. 19) than when the measurement is performed from diagonally below. In such a case, there is a risk that the thermograph 31 will interfere with the scribe line forming device 21 or other devices not shown in the figure, and the degree of freedom in the installation space of the thermograph 31 is reduced. In this second configuration, the thermograph 31 can be installed at a relatively lower position as shown in FIG. 19, compared to the above-mentioned case where the measurement is performed in the horizontal direction or from diagonally above. As a result, the thermograph 31 is less likely to interfere with the scribe line forming device 21 or other devices not shown in the figure, and the degree of freedom in the installation space of the thermograph 31 is increased.

As a third configuration, as shown in FIG. 21, the direction C of each thermograph 31 facing the surface of the glass plate g can be adjusted in the vertical direction. More specifically, each thermograph 31 can be rotated in the D-D direction around a fulcrum 31s on its central axis. Therefore, by changing the direction C of each thermograph 31, the area in which the glass plate g can be measured varies along the vertical direction. In this case, the direction C of each thermograph 31 can be adjusted simultaneously by linking all of the thermographs 31 together, or can be adjusted individually at different times.

According to this third configuration, it is possible to appropriately deal with adverse effects that may occur when the size, thickness, variety, etc. of the glass ribbon G formed and transported in the forming zone 11 is changed, or when the glass sheet g shakes even if this change is not made. That is, when such a change or shaking occurs, the position of the glass sheet g after cutting may shift in the vertical direction. When such a position shift occurs, not only does the detection accuracy of defects occurring in the glass sheet g decrease, but in some cases, a part or all of the glass sheet g may deviate from the area that can be measured by the thermograph 31, making it impossible to detect the defects. According to the configuration here, by adjusting the orientation C of the thermograph 31 in the vertical direction, the area that can be measured by the thermograph 31 can be shifted in response to the vertical shift of the glass sheet g. As a result, the area that can be measured by the thermograph 31 is appropriately corrected, and further high accuracy of defect detection is achieved.

As a fourth configuration, as shown in FIG. 22 (plan view), the direction C of each thermograph 31 facing the surface of the glass plate g can be adjusted in the width direction. More specifically, each thermograph 31 can be rotated in the E-E direction around a fulcrum 31t on its central axis. Therefore, by changing the direction C of the thermograph 31, the area in which the glass plate g can be measured varies along the width direction. In this case, the direction C of each thermograph 31 can be adjusted simultaneously by linking all of the thermographs 31 together, or can be adjusted individually at different times.

According to this fourth configuration, even if the glass plate g after cutting shifts in the width direction due to changes or vibrations similar to those described above, the area in which the glass plate g can be measured by the thermograph 31 is appropriately corrected by adjusting the orientation of the thermograph 31 in the width direction.

As a fifth configuration, as shown in FIG. 23, the vertical position of each thermograph 31 can be adjusted. More specifically, each thermograph 31 can be translated in the vertical direction (F-F direction). Therefore, by changing the vertical position of the thermograph 31, the area in which the glass plate g can be measured varies along the vertical direction. In this case, the vertical position of each thermograph 31 can be adjusted simultaneously by linking all of the thermographs 31 together, or can be adjusted individually at different times.

According to this fifth configuration, even if the glass plate g after cutting shifts in the vertical direction due to changes or vibrations similar to those described above, the area in which the glass plate g can be measured by the thermograph 31 is appropriately corrected by adjusting the vertical position of the thermograph 31.

With regard to the third, fourth and fifth configurations described above, it is possible for the device to have only one of these configurations, or to have two configurations arbitrarily selected from these configurations, or even to have all three of these configurations.

As a sixth configuration, initial settings and more detailed image analysis to detect defects are performed on the thermal image obtained by measurement using the thermograph 31. FIG. 24 shows a thermal image Fw by the thermograph 31 installed at the widthwise end (left end), and FIG. 25 shows a thermal image Fx by the thermograph 31 installed at a location other than both widthwise ends. As an initial setting, a defect inspection area 36 is set on each of the thermal images Fw and Fx shown in these figures, covering the upper end (cutting side end) gt of the glass sheet g and the space Z1 above it. The defect inspection areas 36 set on all of the multiple (three) thermal images Fw and Fx overlap adjacent defect inspection areas 36 in part, and extend over the entire widthwise area of the upper end gt of the glass sheet g.

First, a method of setting the defect inspection area 36 on the thermal image Fw shown in FIG. 24 will be described. First, the upper edge ga1 (its height position) of the glass plate g is detected on the thermal image Fw, and the detected upper edge ga1 is set as the origin position in the vertical direction. Here, detecting the upper edge ga1 of the glass plate g means the following. That is, when the upper cut surface ga of the glass plate g appears as a straight line in the horizontal direction, the cut surface ga is detected as the upper edge ga1. On the other hand, when the upper cut surface ga of the glass plate g appears as a wave shape or a shape inclined with respect to the horizontal direction, for example, the highest or lowest part of the cut surface ga, or the vertical center between the highest and lowest parts, is detected as the upper edge ga1. In this case, if the height difference such as the wave shape or the inclined shape is clearly extremely large, the detection unit 32 can detect it as an obvious defect, so the setting here is not performed.

In addition, in this thermal image Fw, a boundary gf between the ear ge formed at the widthwise end of the glass plate g and the part gc closer to the center in the widthwise direction appears, so the boundary gf is detected and this boundary gf is set as the origin position in the widthwise direction. The origin position in the widthwise direction may be the outer edge gf1 of the ear ge. Then, based on the origin position ga1 in the vertical direction and the origin position gf in the widthwise direction, a rectangular inspection frame 37 elongated in the widthwise direction is drawn superimposed on the thermal image Fw. As a result, the internal area surrounded by the inspection frame 37 is set as the defective inspection area 36. On the thermal image Fw according to this embodiment, the origin position ga1 in the vertical direction is positioned so that it exists in the vertical center of the defective inspection area 36. In addition, one end (left end) of the defective inspection area 36 in the widthwise direction is positioned to the left of the origin position gf based on the origin position gf in the widthwise direction. Furthermore, the other end (right end) in the width direction of the defect inspection area 36 is aligned so as to be present at the right end of the thermal image Fw. Therefore, the defect inspection area 36 here is one area N extracted by one inspection frame 37 so that the left end portion of the upper end gt of the glass plate g becomes the inspection target. The same initial settings as above are also performed for the thermal image Fw captured by the thermograph 31 installed at the right end in the width direction.

According to this method, even if the vertical and widthwise positions of the glass plate g depicted in the thermal image Fw are not uniformly determined, the vertical and widthwise positions of the defect inspection area 36 relative to the glass plate g on the thermal image Fw are uniformly determined. This makes it less likely that erroneous detections will occur when detecting defects occurring in the glass plate g by image analysis in the defect inspection area 36 (described later), and makes it possible to more reliably improve the accuracy of defect detection.

Next, a method of setting the defective inspection area 36 on the thermal image Fx shown in FIG. 25 will be described. In this case, since the width direction end of the glass plate g does not appear on the thermal image Fx, there is no need to detect the origin position in the width direction. Therefore, both ends of the defective inspection area 36 in the width direction are aligned so that they are present at both ends of the thermal image Fx in the width direction. Then, even on this thermal image Fx, the origin position ga1 in the vertical direction is determined, and the defective inspection area 36 is set by the inspection frame 37. Therefore, the defective inspection area 36 here is one area M extracted by one inspection frame 37 so that the central part in the width direction of the upper end gt of the glass plate g becomes the inspection target. The method executed at this time is the same as the method based on FIG. 24 described above. Therefore, according to the method here, if the one due to the origin position in the width direction is excluded, the same action and effect as the method based on FIG. 24 described above can be obtained.

Figure 26 illustrates one form of a part of the region N (M) extracted by the inspection frame 37. In this part of the region N (M), a shape defect due to a wave shape occurs on the upper cut surface ga of the glass plate g. The vertical origin position ga1 shown in the figure is located in the vertical center between the lowest and highest parts of the wave shape (including the wave shapes of other regions). In addition, the wave shape is exaggerated in the figure. This part of the region N (M) is composed of multiple unit pixel groups Pk partitioned vertically and horizontally in a lattice shape. One unit pixel group Pk is a collection of multiple pixels. In this part of the region N (M), the brightness of the group of unit pixel groups Pk arranged horizontally at the bottom (group marked with a circle in the figure) is set as the reference brightness corresponding to the reference temperature. The difference in brightness from this reference brightness identifies the boundary between the upper end gt of the glass plate g and the space Z1 above it. Under such a setting, the unit pixel group Pk including the boundary between the upper end gt of the glass plate g and the space Z1 above it is extracted from among the plurality of unit pixel groups Pk present above the group of unit pixel groups Pk marked with a circle in the figure. In the figure, the plurality of unit pixel groups Pk including the above-mentioned boundary extracted here are marked with a cross. Furthermore, among the plurality of unit pixel groups Pk extracted here, the number of unit pixel groups Pk corresponding to the height difference from the bottom to the top (i.e., the number of stages where a cross mark exists when a horizontal row is considered as one stage) is obtained. Then, if the obtained number is equal to or greater than a preset number, the detection unit 32 detects it as a shape defect due to a corrugated shape, and if the obtained number is less than the preset number, the detection unit 32 determines that it is not a shape defect due to a corrugated shape. In the illustrated example, the obtained number is four and the preset number is three, so the detection unit 32 detects that a shape defect due to a corrugated shape has occurred. This image analysis technique can also be applied in the same manner when the upper cut surface ga of the glass plate g has a shape defect due to the aforementioned horn g1 or chip g2.

According to this image analysis method, the boundary is determined using a fixed position on the glass plate g as the reference brightness based on the vertical origin position ga1 (including the width origin position gf in some cases), which prevents variations and mistakes in determining the boundary each time an inspection is performed. Moreover, the occurrence of defects can be detected simply by finding the number of pixels corresponding to the height difference of the boundary determined by the brightness difference from the reference brightness, ensuring ease and accuracy of image analysis.

Figure 27 illustrates another form in a part of the region N (M) extracted by the inspection frame 37. In this part of the region N (M), a defect occurs on the upper cut surface ga of the glass plate g due to partial damage g3. Here, in this part of the region N (M), the number of unit pixel groups Pk partitioned vertically and horizontally in a lattice shape is greater than in the above case. Therefore, one unit pixel group Pk has fewer pixels than in the above case. Also, in this part of the region N (M), the origin position ga1 in the height direction exists at the boundary between the upper end gt of the glass plate g and the space above it Z1 (excluding the boundary with the partial damage g3). And in the image analysis here, as in the above case, the boundary between the upper end gt of the glass plate g (including the partial damage g3) and the space above it Z1 is identified by the brightness difference from the reference brightness, and the difference between the upper end gt and the space above it Z1 is also identified. Under such settings, a virtual straight line ga11 is drawn in the width direction along the origin position ga1 in the height direction. In this state, the area of the region Zx surrounded by the contours g3a, g3b of the partial damage g3 and the virtual straight line ga11 is calculated from the number of unit pixel groups Pk (or pixels Pk). If the calculated area value is equal to or greater than a preset area value (the area value of the missing part of the glass plate g), the detection unit 32 detects the partial damage g3, and if the calculated area value is less than the preset area value, the detection unit 32 does not determine that the partial damage g3 has occurred. In the illustrated example, since the calculated area value is equal to or greater than the preset area value, the detection unit 32 detects that the partial damage g3 has occurred.

Alternatively, the following method may be adopted. That is, the area of the glass sheet g excluding the above-mentioned region Zx (the area of the glass sheet g depicted in the relevant portion of the region N (M)) may be obtained from the number of unit pixel groups Pk (or pixels Pk). In this case, a value based on the area of the glass sheet g when no defects occur in the glass sheet g (for example, the first threshold value described above) is set in advance. In this way, if the obtained area value exceeds the predetermined area value, the detection unit 32 determines that the partial damage g3 is not present, and if the obtained area value is equal to or less than the predetermined area value, the detection unit 32 detects the partial damage g3. The image analysis method based on FIG. 27 can be similarly applied when the upper cut surface ga of the glass sheet g has a shape defect due to the above-mentioned horn g1 or chip g2, and further when the above-mentioned crack damage g4 due to the vertical crack of the glass ribbon G has occurred. In particular, when detecting cracks or breakage g3 associated with vertical cracks in the glass ribbon G, at least one of the multiple thermal images captured by the multiple thermographs 31 may depict a state in which the glass plate g is completely absent, and therefore, it may be possible to detect the cracks or breakage g3 without calculating the area value from the number of pixels.

According to this image analysis technique, a certain position on the glass plate g is set as the reference brightness based on the vertical origin position ga1 (possibly including the widthwise origin position gf), and the boundary and the difference between the upper end gt and the upper space Z1 are identified. This makes it possible to prevent variations and errors in identifying the boundary and the above differences each time an inspection is performed. Moreover, within the region N (M) whose position has been corrected based on the above origin position ga1 (gf), the occurrence of defects can be detected simply by calculating the area value from the number of pixels, ensuring ease and accuracy of image analysis.

Next, we will explain a glass plate manufacturing method using a glass plate manufacturing apparatus having the above-mentioned configuration.

The glass plate manufacturing method of this embodiment includes a forming process, a conveying process, a cutting process, and a detection process.

The forming process is a process of forming glass ribbon G in the forming zone 11.

The conveying process is a process in which the formed glass ribbon G is conveyed by the roller pair R of the conveying device 14. The conveying process includes a heat treatment process and a cooling process.

The heat treatment process is a process in which the glass ribbon G that has undergone the forming process is subjected to heat treatment while being transported in the heat treatment zone 12.

The cooling process is a process in which the glass ribbon G that has undergone the heat treatment process is cooled while being transported in the cooling zone 13.

The cutting process is a process in which the glass ribbon G that has undergone the cooling process is transported and cut in the width direction by a cutting device 2 to obtain glass sheets g.

The detection process is a process in which the temperature distribution of the measurement objects consisting of the cut side end Gt of the glass ribbon G and the glass plate g is measured using a thermograph 31, and based on the measurement results, it is detected whether or not defects have occurred in the measurement objects Gt, g, as already described in detail.

The above describes a glass plate manufacturing apparatus and a manufacturing method thereof according to an embodiment of the present invention, but the embodiment of the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

In the above embodiment, shape defects of the cut surface of the object to be measured are detected based on the height distribution of the cut surface obtained from a thermal image showing the temperature distribution of the thermograph, but shape defects of the cut surface of the object to be measured may also be detected by other image analysis methods.

In the above embodiment, partial breakage of the glass sheet g and vertical cracks in the glass ribbon G are detected based on the area of the glass sheet g and a threshold value, but partial breakage and vertical cracks may be detected by other image analysis. Furthermore, the area of the glass sheet g may be calculated as the entire area of the glass sheet g, or as a portion of the area of the glass sheet g. For example, the area of the middle part of the glass sheet g gripped by the chuck 27 excluding both ends may be calculated, and partial breakage of the glass sheet g and vertical cracks in the glass ribbon G may be detected based on the area of the middle part and a threshold value.

In the above embodiment, the temperature of the measurement objects Gt, g was measured by measuring the temperature distribution using a thermograph 31, but instead, the temperature distribution of the measurement objects Gt, g may be measured using a linear sensor thermometer capable of measuring temperature in a straight line.

In the above embodiment, the measurement object includes both the cut side end Gt of the glass ribbon G and the glass plate g, but only one of these may be the measurement object.

In the above embodiment, defects such as horns, chips, corrugations, partial breakage, and breakage associated with vertical cracks are detected individually for each measurement object, but there are cases where multiple types of defects occur simultaneously on a single measurement object. In such cases, multiple types of defects (the presence or absence of those defects) may be detected for a single measurement object.

In the above embodiment, the glass ribbon G was formed by the overflow downdraw method, but it may also be formed by other downdraw methods such as the slot downdraw method or the redraw method, or the float method.

In the above embodiment, the glass ribbon G is cut by folding along the scribe line S, but other methods such as laser cutting or laser melting may also be used. Even when such a method is used, vibrations and impacts are generated when the glass sheet g is separated from the glass ribbon G, which may cause shaking in the glass ribbon G and the glass sheet g. However, the present invention is less susceptible to the adverse effects of such shaking.

In the above embodiment, the thermal images shown in Figures 9 to 14 are part of a thermal image obtained by one thermograph, but these thermal images may be the entire thermal image of one of the thermal images obtained by a plurality of thermographs (see Figure 17). In this case, the glass ribbon may not be depicted in the thermal image as shown in Figures 26 and 27 when detecting a defect. In addition, the entire glass sheet is depicted in the thermal images shown in Figures 15 and 16, but only the upper portion of the glass sheet (e.g., the upper end) may be depicted, and in that case, only a portion of the glass sheet in the width direction (and only a portion of the glass ribbon in the width direction) may be depicted. In such a case, the glass ribbon may not be depicted as shown in Figures 26 and 27 when detecting a defect.

1 Processing device 2 Cutting device 3 Detection device 11 Forming zone 14 Conveying device 22 Cutting device 31 Thermography 32 Detection unit 36 Defective inspection area F1 Thermal image F2 Thermal image F3 Thermal image F4 Thermal image F5 Thermal image Fw Thermal image Fx Thermal image G Glass ribbon Gt Cutting side end g of glass ribbon Glass sheet G1 Horn g1 Horn G2 Chipped g2 Chipped G3 Partial break g3 Partial break G4 Vertical crack g4 Vertical crack Ga Lower cut surface ga of glass ribbon Upper cut surface ga1 of glass sheet Origin position in the vertical direction (upper edge of glass sheet)
Gm Molten glass Z1 Space above the glass plate

Claims (18)

A glass sheet manufacturing method including: a forming step of forming a glass ribbon in a forming zone; a conveying step of conveying the glass ribbon along a longitudinal direction; and a cutting step of cutting the glass ribbon along a width direction to cut out a glass sheet,
A detection process is provided in which a cut-side end of the glass ribbon after cutting in the cutting process, a glass sheet, or any one of them is used as a measurement object, a temperature is measured for the measurement object, and a defect occurring in the measurement object is detected based on the measurement result ,
The method for manufacturing a glass plate , wherein in the detection step, the temperature of the measurement object is measured by measuring a temperature distribution by thermography . The method for manufacturing a glass sheet according to claim 1, characterized in that in the cutting step, the glass sheet is cut by bending and breaking the glass ribbon along scribe lines extending in the width direction of the glass ribbon. 3. The method for manufacturing a glass sheet according to claim 1, wherein in the forming step, the glass ribbon is formed by a down-draw method. The glass plate manufacturing method according to claim 3, characterized in that the defects detected in the detection process include defects in the shape of the upper cut surface of the glass plate after cutting in the cutting process. The glass plate manufacturing method according to claim 4, characterized in that the distribution of height positions of the upper cut surface is calculated from the temperature distribution of the glass plate, and a shape defect of the upper cut surface is detected based on the height. The glass plate manufacturing method according to claim 4 or 5, characterized in that if a defective shape of the upper cut surface is detected, the glass plate is discarded. A glass plate manufacturing method according to any one of claims 3 to 6, characterized in that the defects detected in the detection process include partial breakage of the glass plate after cutting in the cutting process. The glass plate manufacturing method according to claim 7, characterized in that the area of at least a portion of the glass plate is calculated from the temperature distribution of the glass plate, and the partial breakage is detected based on the area and a first threshold value. The glass plate manufacturing method according to claim 7 or 8, characterized in that, if the partial breakage is detected, the glass plate is discarded. A glass sheet manufacturing method according to any one of claims 3 to 9, characterized in that the defects detected in the detection process include cracks and breakage of the glass sheet due to vertical cracks in the glass ribbon after cutting in the cutting process. The glass plate manufacturing method according to claim 10, characterized in that the area of at least a portion of the glass plate is calculated from the temperature distribution of the glass plate, and the crack or breakage is detected based on the area and a second threshold value. The glass sheet manufacturing method according to claim 10 or 11, characterized in that, when the crack or breakage is detected, it is assumed that a vertical crack has occurred in the glass ribbon, and the cutting device used to perform the cutting process is withdrawn. A glass plate manufacturing method according to any one of claims 3 to 12, characterized in that the thermography measures the temperature distribution of the measurement object from diagonally below. A glass plate manufacturing method according to any one of claims 3 to 13, characterized in that the direction of the thermograph toward the surface of the object to be measured can be adjusted in the vertical direction. A glass plate manufacturing method according to any one of claims 3 to 14, characterized in that the direction in which the thermograph is directed toward the surface of the object to be measured can be adjusted in the width direction. A glass plate manufacturing method according to any one of claims 3 to 15, characterized in that the thermography is adjustable in its vertical position. A glass plate manufacturing method according to any one of claims 3 to 16, characterized in that the height position of the upper edge of the glass plate after cutting is detected on a thermal image obtained by measuring the temperature distribution using the thermography, and this detected height position is set as the origin position in the vertical direction to set a defect inspection area that covers the upper end of the glass plate and the space above it, and defects occurring in the glass plate are detected by image analysis within the defect inspection area. A glass sheet manufacturing apparatus including: a forming zone for forming a glass ribbon; a conveying device for conveying the glass ribbon along a longitudinal direction; and a cutting device for cutting the glass ribbon along a width direction to cut out a glass sheet,
A detection device is provided that measures the temperature of a cut-side end of the glass ribbon after cutting by the cutting device, a glass sheet, or one of the two, and detects defects occurring in the measurement object based on the measurement result ,
The glass sheet manufacturing apparatus , wherein the detection device measures the temperature of the measurement object by measuring a temperature distribution using a thermograph .

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