KR20170116955A - Glass crack detection method, glass crack detector, glass plate polishing method, glass plate polishing device, and glass plate production method - Google Patents

Abstract

A glass breakage detecting method, a glass breakage detecting apparatus, a glass sheet polishing method, a glass sheet polishing apparatus, and a glass sheet manufacturing method capable of detecting glass sheet breakage at an early stage are provided.
The glass breakage detecting apparatus 1 comprises a liquid supply section 2 for supplying a liquid L to a glass plate G, an AE sensor 4 disposed at a position for contacting the liquid L, And a signal processing section 6 for processing an AE signal input from the AE sensor 4 which detects the elastic wave of the AE sensor 4. The signal processing section 6 of the glass breakage detecting apparatus 1 judges the breaking of the glass plate G when the AE signal from the AE sensor 4 exceeds a predetermined threshold value.

Description

TECHNICAL FIELD [0001] The present invention relates to a glass crack detection method, a glass crack detection apparatus, a glass sheet polishing method, a glass sheet polishing apparatus, and a glass sheet manufacturing method. }

The present invention relates to a glass breakage detecting method, a glass breakage detecting apparatus, a glass sheet polishing method, a glass sheet polishing apparatus, and a glass sheet manufacturing method.

In the manufacturing process of the glass plate, various processes such as cutting, chamfering, boring, polishing, conveying, cleaning and the like are performed on the glass plate. For example, a glass plate used for a flat panel display (FPD) such as a liquid crystal display (LCD) or an organic light-emitting diode (OLED) The surface of the glass plate may be partially or entirely polished by a polishing apparatus.

In order to carry out such polishing, there is known a polishing apparatus having a moving polishing head for carrying and carrying a glass plate, and a plurality of polishing platens arranged below the polishing head. According to this polishing apparatus, the glass plate is transported by the moving polishing head, and the glass plates are sequentially polished in a plurality of polishing platens.

However, during the polishing of the glass plate by the polishing apparatus, the glass plate is rarely broken. In such a case, if the polishing process is continued while the glass plate is broken, the polishing pad is damaged by the broken glass piece. Further, during continuous polishing in which a plurality of glass plates are successively polished in the production process, there arises a problem that the subsequent glass plate is adversely affected. For this reason, it is desired that the breaking of the glass plate is detected early and the polishing apparatus is quickly stopped.

Patent Literature 1 discloses a break detection apparatus that detects breakage of a glass plate during polishing using a processed sound. The glass breakage detecting device collects processed sounds generated during polishing by a microphone, extracts acoustic waves of a predetermined frequency (3 kHz or more) from the collected processed sounds by a filter, The breakage of the glass plate is judged by comparing the sound wave level with the normal sound wave level in the past predetermined time from now.

Patent Document 2 discloses a polishing apparatus for detecting breakage of a glass plate during polishing using an elastic wave. In the polishing apparatus, an acoustic wave from a glass plate is detected by an AE (Acoustic Emission) sensor provided on a glass plate and a table supporting a polishing pad, and an abnormality during polishing is detected based on an output signal from the AE sensor.

Japanese Patent Application Laid-Open No. 2006-035343 International Publication No. 2010/067732

In the breakage detecting device described in Patent Document 1, the glass plate can be detected only by sound in a scattered state, and it is difficult to detect the sound of the initial stage of cracking (microcracks such as cracks, defects). In addition, it is susceptible to the influence of noise of surrounding speech frequency components.

If the glass plate is broken into small pieces, it will damage the polishing pad as described above, and it takes several hours for cleaning to remove it. As a result, the time required for the return operation and the polishing operation in the production process are interrupted, resulting in a drawback that the operation rate is lowered.

In the polishing apparatus described in Patent Document 2, the elastic wave from the glass plate is detected by the AE sensor through various members such as a table and a plate, so that the elastic wave may be attenuated before being transmitted to the AE sensor. Therefore, it is difficult to detect the low-level seismic waves generated in the initial stage of the cracking by the AE sensor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and provides a glass breakage detecting method, a glass breakage detecting apparatus, a glass sheet polishing method, a glass sheet polishing apparatus, and a glass sheet manufacturing method capable of detecting breakage of a glass sheet at an early stage .

According to an aspect of the present invention, there is provided a glass breakage detecting method comprising: a detecting step of detecting an AE signal from the AE sensor while bringing a glass plate into contact with a liquid and bringing the AE sensor into contact with the liquid; Of the glass plate exceeds a predetermined threshold value.

According to another aspect of the present invention, there is provided a glass breakage detecting apparatus comprising: a liquid supply unit for supplying a liquid to a glass plate; an AE sensor disposed at a position in contact with the liquid; and a signal processing unit for processing an AE signal input from the AE sensor And the signal processing unit determines that the glass plate is broken by the AE signal exceeding a predetermined threshold value.

According to another aspect of the present invention, a glass plate polishing method is a glass plate polishing method for polishing a surface of a glass plate by a polishing pad while supplying an abrasive liquid between a polishing pad and a glass plate, And a crack detection process by the above-described glass breakage detection method.

According to another aspect of the present invention, a polishing apparatus for a glass plate is a polishing apparatus for a glass plate having a liquid supply section for supplying a polishing liquid to a glass plate and a polishing pad for polishing the surface of the glass plate, Described glass breakage detecting device.

According to another aspect of the present invention, there is provided a method of manufacturing a glass plate, comprising the steps of: forming the glass plate from molten glass into plate-shaped glass; cutting the plate-shaped glass into a glass plate; Process.

According to the glass breakage detecting method, the glass breakage detecting apparatus, the glass sheet polishing method, the glass sheet polishing apparatus, and the glass sheet manufacturing method of the present invention, breakage of the glass sheet in the initial stage can be detected.

1 is a configuration diagram of a glass breakage detecting apparatus.
2 (A) is a waveform of an AE signal due to noise, and Fig. 2 (B) is a waveform of an AE signal caused by an acoustic wave caused by glass breakage.
3 is a perspective view of the AE sensor.
4 is a configuration diagram of the single-piece polishing apparatus.
5 is a configuration diagram of the continuous polishing apparatus.
6 is a plan view of the continuous polishing apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is described by the following embodiments. However, the present invention can be modified in many ways without deviating from the scope of the present invention, and other embodiments other than the described embodiments can be used. Accordingly, all modifications within the scope of the present invention are included in the claims. Here, in the drawings, portions indicated by the same symbols are basically the same elements having the same function.

(Glass breakage detecting device, and detection method)

1 is a schematic block diagram of a glass breakage detecting apparatus. The glass breakage detecting apparatus 1 includes a liquid supply portion 2 for supplying a liquid L to a glass plate G, an AE sensor 4 disposed at a position in contact with the liquid L, an AE sensor 4, And a signal processing unit 6 for processing an AE signal inputted from the AE signal processing unit.

The liquid supply portion 2 is not particularly limited as long as it can supply the liquid L to the glass plate G. [ As the liquid supply portion 2, for example, a nozzle or the like can be applied.

The AE sensor 4 means a sensor capable of detecting an elastic wave generated from the glass plate G and is not particularly limited as long as it can detect an elastic wave. The AE sensor 4 has, for example, a piezoelectric element, and the acoustic wave can be detected by the piezoelectric element.

The AE signal means an electric signal that is output from the AE sensor 4 and input to the signal processing unit 6. [ The AE signal includes an electrical signal from the AE sensor 4, an amplified and / or filtered electrical signal.

In addition, AE (acoustic emission) means a phenomenon in which a sound generated when a solid is deformed or broken is released as an acoustic wave.

The AE sensor 4 is disposed at a position in contact with the liquid L. The position of contact with the liquid L means a state in which the glass plate G and the AE sensor 4 are in contact with each other through the liquid L and the glass plate G and the AE sensor 4 are not in contact with each other.

In the present embodiment, the elastic wave generated from the glass plate G is detected by the AE sensor 4 through the liquid L. Conventionally, an AE sensor measures an elastic wave transmitted in a solid state, and it has been necessary to measure the AE sensor by bringing the AE sensor into direct contact with the object to be measured. 1, since the path of an acoustic wave between the glass plate G and the AE sensor 4 is formed solely of the liquid L, a gas is interposed between the glass plate G and the AE sensor, It is possible to suppress the attenuation of the acoustic wave received by the AE sensor 4, That is, the low-level seismic waves at the initial stage due to the cracking of the glass plate G are not attenuated. Therefore, the AE sensor 4 can detect an elastic wave of low level in the initial stage due to the breakage of the glass plate G. Also, if the glass plate G is in contact with the liquid, it is possible to detect the acoustic waves even if the glass plate G moves. In the present specification, cracking of the glass plate (G) includes micro cracks, defects, and cracks such as cracks generated in the glass plate (G).

If it is possible to form a path of an acoustic wave, it is preferable to use, as the liquid L, a polishing liquid, a cleaning liquid, water or the like used in the production process of the glass plate.

In the present embodiment, the AE sensor 4 and the signal processing unit 6 are electrically connected by a PLC (Power Line Communication) cable 10, and the AE signal is supplied to the signal processing unit 6 . In the present embodiment, the preamplifier 12 and the disc remover 14 are preferably connected to the PLC cable 10 connecting the AE sensor 4 and the signal processing unit 6, Respectively.

Since the preamplifier 12 can amplify a weak AE signal from the AE sensor 4, it is preferable that the preamplifier 12 is provided on the PLC cable 10. The case where the preamplifier 12 is installed in the PLC cable 10 is explained, but the present invention is not limited to this, and an AE sensor with a built-in preamplifier can be used. As a result, the number of parts can be reduced.

The disc remover 14 is a filter capable of discriminating the AE signal before being input to the signal processing unit 6 and filtering the signal in a frequency range necessary for detection of breakage. The disc remover 14 is a PLC cable 10).

As the AE sensor 4, it is preferable to use an AE sensor capable of detecting acoustic waves having a resonance frequency of 140 kHz or more and 150 kHz or less in order to satisfactorily detect breakage in the initial stage of the glass plate G. [ The resonance frequency is preferably set near the center of the frequency band to be detected.

It is preferable that the frequency band of the AE signal input from the AE sensor 4 to the signal processing unit 6 is set in the range of 100 kHz to 200 kHz by the disc remover 14, for example. And more preferably in the range of 120 kHz to 180 kHz.

Various devices such as a cutting device, a chamfering device, a punching device, a polishing device, a transporting device, and a cleaning device are installed around the manufacturing process of the glass plate G. [ It may be necessary to exclude acoustic waves having a frequency of less than 100 kHz due to mechanical vibrations from these devices. In addition, it may be necessary to exclude acoustic waves having a frequency exceeding 200 kHz due to electrical noise.

In the present embodiment, since the lower limit value of the frequency band inputted from the AE sensor 4 to the signal processing section 6 is set to 100 kHz, erroneous detection due to acoustic waves of mechanical vibration can be prevented. Further, since the upper limit value is set to 200 kHz, erroneous detection due to acoustic waves of electrical noise can be prevented. In this manner, it is preferable to discriminate the surrounding noise component by selecting a frequency band of interest and setting a predetermined filter.

The glass breakage detecting apparatus 1 of the present embodiment includes a table 16 and a table pad 18 disposed on the table 16. [ A glass plate G is stacked on the table pad 18. The table 16 is not particularly limited as long as the glass plate G can be loaded. The surface on which the glass plate G of the table 16 is mounted is preferably a flat surface. The table pad 18 is made of, for example, foamed urethane, and is used for fixing the glass plate G. [

The AE signal from the AE sensor 4 is input to the signal processing unit 6. [ The signal processing unit 6 includes an arithmetic unit for performing various arithmetic operations, various programs, and a storage unit (not shown) storing data and the like. In the glass breakage detecting apparatus 1, the elastic wave generated from the glass plate G is detected by the AE sensor 4 through the liquid L. The AE signal is input from the AE sensor 4 to the signal processing unit 6. [

The signal processing section 6 can set in advance a threshold value (e.g., voltage) that is considered to have caused the breaking of the glass plate G, and can store the threshold value in the storage section. The operation unit of the signal processing unit 6 can compare the input AE signal with a preset threshold value. The signal processing section 6 can detect the breakage of the glass plate G by detecting the AE signal exceeding the predetermined threshold value.

Next, a glass breakage detecting method by the glass breakage detecting apparatus 1 of the present embodiment will be described.

A glass plate G is disposed on the table pad 18 on the table 16. [ The glass sheet G is attracted and held by either one of the two main surfaces of the glass sheet G by the table pad 18. [ The liquid L is supplied from the liquid supply portion 2 toward the glass plate G to bring the glass plate G and the liquid L into contact with each other. A predetermined amount of liquid L is supplied to the glass plate G so that the liquid level of the liquid L rises and the liquid L and the AE sensor 4 come into contact with each other. Therefore, the glass plate G and the AE sensor 4 are in contact through the liquid L.

When the AE sensor 4 is disposed above the glass plate G, the distance between the glass plate G and the AE sensor 4 is preferably 0.5 mm or more and 5 mm or less. In this range, the AE sensor 4 can detect the elastic waves from the glass plate G with sensitivity. It is also preferable that the distance is set to 1 mm or more because the glass plate G and the AE sensor 4 can be prevented from coming into contact with each other. It is also preferable that the distance is 2 mm or less because excessive use of the liquid L can be avoided.

Further, the AE sensor 4 may be arranged on the side of the glass plate G. By arranging the AE sensor 4 on the side, interference between the processing device and the AE sensor 4 can be easily avoided when processing such as machining is performed on the surface of the glass plate G. In this case, the distance between the glass plate G and the AE sensor 4 is preferably 0.5 mm or more and 150 mm or less. 150 mm, the elastic wave from the glass plate G can be detected by the AE sensor 4. Preferably 120 mm or less.

(Such as cutting, chamfering, boring, polishing, transporting, cleaning, etc.) necessary for manufacturing the glass plate G is performed on the glass plate G, for example. In the detection step, the AE sensor 4 detects the elastic wave generated from the glass plate G through the liquid L. The AE signal from the AE sensor 4 is input to the signal processing unit 6. [ When the glass plate G is cracked during the processing of the glass plate G, an elastic wave is generated in the glass plate G.

This elastic wave is transmitted to the AE sensor 4 via the breaking point of the glass plate G, the entire surface of the glass plate G, and the liquid L. At this time, in the present embodiment, since only the liquid L is interposed in the propagation path of the acoustic wave, the acoustic wave is hardly attenuated. Therefore, even when the level of the acoustic wave is low, it is possible to detect the acoustic wave with the AE sensor 4 with high sensitivity. The AE sensor 4 can detect a low-level elastic wave occurring at the initial stage of the cracking of the glass plate G. [

The AE sensor 4 which detects an elastic wave generated from the glass plate G outputs an AE signal. The AE signal from the AE sensor 4 is input to the signal processing unit 6 via the PLC cable 10 via the preamplifier 12 and the disc remover 14.

The above-described threshold value is stored in the storage section of the signal processing section 6. [ The operation unit of the signal processing unit 6 compares the always inputted AE signal with a predetermined threshold value. In the judging process, the signal processing section 6 judges that the glass plate G is broken by the AE signal from the AE sensor 4 exceeding the predetermined threshold value.

The signal processing unit 6 determines whether the glass plate G is broken by determining whether the AE signal exceeds a predetermined threshold value. The threshold value is appropriately set in accordance with the environment. As a method for setting a predetermined threshold value, the following method can be exemplified. For example, a value obtained based on an experimental value or experience value can be stored in the signal processing section 6 as a predetermined threshold value.

Further, it is possible to store the value calculated by the automatic threshold value adjusting function in the signal processing section 6 as a predetermined threshold value. It is possible to incorporate the automatic threshold value adjustment function into the operation section of the signal processing section 6. [ The automatic threshold value adjustment function stores the input AE signal and time in the storage unit of the signal processing unit 6 and calculates the average value of the AE signal within a predetermined time based on the input AE signal and time And a value that is 1.5 times the average value of the AE signal can be set as a threshold value. When it is desired to detect a low-level seismic wave, a value that is 1.2 times the average value of the AE signal may be a threshold value or may be set arbitrarily according to a detection signal. The time for calculating the average value of the AE signal can be arbitrarily set.

In the present embodiment, the AE sensor 4 can detect low-level elastic waves. Therefore, the predetermined threshold value set in the signal processing section 6 can be lowered. On the other hand, the AE sensor 4 may also detect a vibration (hereinafter, noise) caused by an acoustic wave or a disturbance which is considered to be not caused by glass breakage. If the predetermined threshold value set in the signal processing section 6 is made low, it may be difficult to distinguish acoustic waves and noise caused by glass breakage.

The inventors of the present invention have studied the elastic waves and noise caused by glass breakage. As shown in Fig. 2, the waveform of the AE signal input from the AE sensor 4 to the signal processing unit 6 is a wave of elasticity And noise.

2 is a waveform graph of an AE signal, wherein the vertical axis represents voltage, and the horizontal axis represents time. 2 (A) shows the waveform of the AE signal due to the noise, and Fig. 2 (B) shows the waveform of the AE signal due to the acoustic wave caused by glass breakage. Comparing the waveform of the AE signal caused by the noise shown in Fig. 2A and the waveform of the AE signal caused by the acoustic wave caused by the glass breakage shown in Fig. 2B, The duration of time until It can be understood that the continuation time t2 of the AE signal due to the acoustic wave caused by glass breakage is longer than the continuation time t1 due to the noise.

By using the difference in length of the continuous time, it becomes possible to distinguish acoustic waves and noise caused by glass breakage. Since the continuous time t2 of the AE signal due to the acoustic wave caused by the glass breakage is long, the AE signal exceeding the predetermined threshold value is continuously input to the signal processing unit 6. [ On the other hand, since the continuous time t1 of the AE signal due to the noise is short, the AE signal exceeding the predetermined threshold value is inputted to the signal processing unit 6 in a short time compared with the acoustic wave caused by the glass breakage. Therefore, the signal processing section 6 can judge that it is an elastic wave caused by breakage when the AE signal continuously exceeds the predetermined threshold value, and judges that it is noise if the AE signal only temporarily exceeds the predetermined threshold value . Therefore, it is possible to distinguish acoustic waves and noise caused by glass breakage. In the signal processing section 6, it is possible to detect an acoustic wave caused by glass breakage with good sensitivity, and as a result, it is possible to judge breakage of the glass in the initial stage.

It is possible to set whether or not the AE signal is judged to be broken when the AE signal exceeds the threshold value continuously for a certain period of time in the signal processing section 6. The time for continuously measuring the AE signal is stored in the storage section of the signal processing section 6 . For example, it can be determined that the signal processing unit 6 is broken when the predetermined threshold value is continuously exceeded for 150 msec. 2, for example, when the predetermined threshold value is set to 1.000 (V), the AE signal due to noise temporarily exceeds a predetermined threshold value. However, when 150 msec is not elapsed, It is understood that the AE signal caused by the acoustic wave caused by the glass breakage exceeds the predetermined threshold value for 150 msec or more.

By appropriately setting the threshold value and the time, it is possible to easily distinguish acoustic waves and noise caused by glass breakage. Here, the term " continuous " means that the time is shorter than that of continuous, and the term " continuous "

In the above description, it is determined that the AE signal is broken when the AE signal continues to exceed the predetermined threshold (voltage). However, since it can be set appropriately according to the state of breakage of the glass plate G to be detected, Do not. For example, the AE signal is measured every predetermined time (for example, 30 msec) and the number of generated AE signals exceeding a predetermined threshold value (for example, voltage) is counted. (For example, five times) of the number of consecutive occurrences is set in advance. It may be determined that the number of consecutive occurrences of the AE signal exceeding a predetermined threshold value (voltage) exceeds the threshold value (for example, five times) of consecutive occurrences. By appropriately setting a predetermined threshold value (voltage) for the AE signal and a threshold value for the number of consecutive occurrences, it is possible to easily distinguish acoustic waves and noise caused by glass breakage.

In the initial stage of breaking of the glass plate G, as described above, low-level elastic waves are continuously generated. On the other hand, when the degree of breakage of the glass plate G is large, for example, when the glass plate G is broken, there is a case where a high-level seismic wave occurs occasionally. There may be a situation in which it is necessary to detect a seismic wave having such a high level that occurs at a short time.

In order to cope with such a case, it is desirable to set the first threshold value at a low level and the second threshold value at a high level as a threshold at which cracking of the glass plate G is recognized.

When the AE signal exceeding the first threshold value and not exceeding the second threshold value is input to the signal processing section 6, the signal processing section 6 determines that the AE signal is broken when the AE signal is continuously detected. On the other hand, when the AE signal exceeding the second threshold value is inputted to the signal processing section 6, it is preferable that the signal processing section 6 judges that even if the AE signal is detected once, it is broken. By setting the first threshold value of the low level and the second threshold value of the high level, it is possible to determine the breaking of the glass plate G according to the degree of cracking of the glass plate G. [

Next, a preferred embodiment of the AE sensor 4 used in the glass breakage detecting apparatus 1 will be described. 3 is a perspective view of the AE sensor 4. Fig. The AE sensor 4 includes a receiving plate 4A for detecting an elastic wave, a piezoelectric element (not shown) provided on the receiving plate 4A, a conductive casing 4B surrounding the piezoelectric element, And a connector 4C provided on the casing 4B for electrically connecting the cable 10 to each other.

There is a possibility that noise may be generated by conduction between the casing 4B and the liquid L when the AE sensor 4 and the liquid L come into contact with each other. It is preferable to electrically isolate the AE sensor 4 and the liquid L in order to prevent electrical noise. In this embodiment, as shown in Fig. 3, an insulating plate 20 (for example, a ceramic plate) can be provided on the receiving plate 4A. The receiving plate 4A and the insulating plate 20 are closely contacted with each other using a grease or an instant adhesive. As a result, the gas does not intervene between the receiving plate 4A and the insulating plate 20, and the attenuation of the AE signal can be reduced. The casing 4B can be covered with an insulating resin tube 22 (for example, a silicone tube) and the connector 4C can be covered with an insulating resin tube 24 (for example, a silicone tube) Can be covered. An insulating plate 26 may be provided on the opposite side of the receiving plate 4A of the AE sensor 4. [ The insulating plates 20 and 26 and the resin tube 24 can be sealed with an insulating sealing material (silicone resin).

It is preferable that the AE sensor 4 and the liquid L are electrically insulated from each other so that generation of electrical noise can be suppressed.

(A polishing apparatus for a glass plate, and a polishing method)

Next, a glass plate polishing apparatus capable of detecting glass breakage and a polishing method will be described.

4 is a configuration diagram of a single-piece glass plate polishing apparatus. The polishing apparatus 30 is, for example, a glass plate G made in a rectangular shape (for example, a float including 2000 x 2200 mm to 2200 x 2600 mm in one side and 0.7 mm in thickness, including a non-alkali glass- (For example, AN100) manufactured by a conventional method is used to polish the surface of the glass plate until the flatness required for the glass plate for liquid crystal display is reached.

The surface opposite to the polishing surface of the glass plate G is disposed on the table 16 and is attracted and held on the table pad 18. [ The polishing pad 32 is provided on the lower surface of the polishing head 34 so as to face the polishing surface of the glass plate G. [ The upper surface of the polishing head 34 is fixed to the rotary shaft 36.

A rotating elevating device 38 is connected to the rotating shaft 36. The rotating and elevating device 38 controls the rotation and elevating operation in synchronism with the conveying timing of the glass plate G by the table 16 by the control section 40 that controls the entire polishing device 30 as a whole.

The polishing head 34 and the rotary shaft 36 are provided with an abrasive liquid supply portion 42 which is a liquid supply portion formed by a through hole. The polishing liquid 44 can be supplied to the glass plate G from the polishing liquid supply portion 42. [ As the polishing liquid 44, for example, a polishing slurry such as a cerium oxide aqueous solution can be used. Further, the polishing pad 32 and the polishing head 34 can be rotated and revolved by the rotary elevating device 38. [

The polishing apparatus 30 of the present embodiment includes an AE sensor 4 and a signal processing unit 6 electrically connected to the AE sensor 4. [ The signal processing unit 6 is included in the control unit 40 as a part of the function. The AE sensor 4 is disposed at a position where it contacts the polishing liquid 44. [ A polishing pad may be provided on the table 16 side and a suction pad may be provided on the head side so as to adsorb the glass plate G so as to form a shape opposite to that of Fig.

Next, a preferable method of polishing the glass plate by the polishing apparatus 30 of the present embodiment will be described.

A glass plate G is disposed on the table pad 18 on the table 16. [ The surface of the glass plate G opposite to the polishing surface of the glass plate G is attracted and held by the table pad 18.

The polishing liquid 44 is supplied from the polishing liquid supply unit 42 toward the glass plate G so that the glass plate G and the polishing liquid 44 come into contact with each other. The liquid level of the polishing liquid 44 rises and the polishing liquid 44 comes into contact with the AE sensor 4 by supplying a predetermined amount of the polishing liquid 44 to the glass plate G. Therefore, the glass plate G and the AE sensor 4 are brought into contact with each other through the polishing liquid 44.

The polishing pad 32 and the polishing head 34 are rotated by the rotary elevating device 38 while the abrasive liquid 44 is being supplied and the wafer is revolved to be polished by the polishing pad 32 G) is polished. The rotation and elevation device 38 controls the rotation speed and the descending operation (pressing force) suitable for polishing the glass plate G by the control section 40 that controls the entire polishing device 30 in a general manner.

The AE sensor 4 detects the elastic wave from the glass plate G through the polishing liquid 44. [ When cracking of the glass plate G occurs while the glass plate G is being polished, an elastic wave is generated in the glass plate G.

This elastic wave is transmitted to the AE sensor 4 via the breaking point of the glass plate G, the entire surface of the glass plate G, and the polishing liquid 44. At this time, in the present embodiment, since only the polishing liquid 44 is interposed in the propagation path of the acoustic wave, the acoustic wave is hardly attenuated. Therefore, even when the level of the acoustic wave caused by glass breakage is low, it is possible to detect the acoustic wave with sensitivity by the AE sensor 4. The AE signal from the AE sensor 4 is input to the signal processing unit 6 of the control unit 40. [ The signal processing unit 6 judges that the glass plate G is broken because the AE signal from the AE sensor 4 exceeds a predetermined threshold value. It is possible to detect the low level of elastic waves generated in the initial stage of the cracking of the glass plate G which is generated at the time of polishing by the AE sensor 4 so that breakage of the glass plate G in the initial stage can be judged.

Next, a continuous glass plate polishing apparatus will be described. Fig. 5 is a configuration diagram of the continuous polishing apparatus, and Fig. 6 is a plan view of the continuous polishing apparatus. Further, in the plan view of Fig. 6, glass plates G are mounted on all the tables 16. Fig. 4 are denoted by the same reference numerals and the description thereof may be omitted.

As shown in Figs. 5 and 6, the polishing apparatus 50 may be a glass plate G (for example, one side is 2000 x 2200 mm to 2200 x 2600 mm, a thickness is 0.7 mm, (For example, AN100) prepared by a float method including a non-alkali glass-based material (for example, AN 100)) is placed on a table pad 18 on a table 16, and the table 16 is continuously transported , The polishing surface of the glass plate G on the table 16 is continuously polished by a plurality of polishing pads 32, 32 ... arranged along the conveying path. By the continuous polishing, the polishing apparatus 50 polishes and removes minute unevenness and curvature of the surface to be polished of the glass plate G to produce a glass plate that satisfies the flatness required in the glass plate for liquid crystal display.

The table 16 can be continuously transported along a rail (not shown) in the horizontal direction indicated by the arrow by a transporting device (not shown). A plurality of polishing pads 32 are provided on the lower surface of the plurality of polishing heads 34 so as to face the polishing surface of the glass plate G at positions opposed to the conveying path during the transportation of the table 16. The polishing surface of the glass plate G can be polished by the respective polishing pads 32 to the flatness required by the glass plate for liquid crystal display.

Each of the polishing head 34 and the rotary shaft 36 is provided with a polishing liquid supply portion 42 which is a liquid supply portion formed by a through hole. The polishing liquid 44 can be supplied to the glass plate G from the polishing liquid supply portion 42. [ As the polishing liquid 44, for example, a polishing slurry such as a cerium oxide aqueous solution can be used. Each of the polishing pad 32 and the polishing head 34 can be rotated and revolved by the rotary elevating device 38. [

The polishing apparatus 50 of the present embodiment includes a plurality of AE sensors 4 and a signal processing unit 6 electrically connected to the AE sensor 4. [ The signal processing unit 6 is included in the control unit 40 as a part of the function. The AE sensor 4 is disposed at a position where it contacts the polishing liquid 44. [

In the present embodiment, as shown in Figs. 5 and 6, a plurality of AE sensors 4 are arranged at positions corresponding to the respective polishing heads 34. In Fig. That is, one polishing head 34 and one AE sensor 4 constitute one set. The AE sensor 4 detects an elastic wave of the glass plate G which is polished by the polishing pad 32 when passing through the polishing head 34.

The AE signal from the AE sensor 4 is input to the signal processing unit 6 of the control unit 40. [ The signal processing unit 6 judges that the glass plate G is broken because the AE signal from the AE sensor 4 exceeds a predetermined threshold value. It is possible to detect the low level elastic waves generated in the initial stage of the cracking of the glass plate G generated during the polishing by the AE sensor 4, Can be determined.

When it is determined that the glass plate G is broken in one stage of the polishing process of the glass plate G, an alarm is given to stop the polishing apparatus 50. [ When the breakage of the glass plate G is not judged, the table 16 on which the glass plate G is continuously carried is conveyed to the next stage in the horizontal direction. In the next stage of the polishing process, the glass plate G is polished by the polishing pad 32 provided on the polishing head 34. When the glass plate G is polished, the AE sensor 4 is brought into contact with the polishing liquid 44. The AE sensor 4 detects a seismic wave from the glass plate G through the polishing liquid 44. The AE signal from the AE sensor 4 is input to the signal processing unit 6 of the control unit 40. [ The signal processing unit 6 can judge that the glass plate G is broken by the AE signal from the AE sensor 4 exceeding the predetermined threshold value.

In this embodiment, since one polishing head 34 and one AE sensor 4 constitute one set, in the continuous polishing apparatus 50, the glass plate G is cracked at any stage Can be detected.

The number of the polishing heads 34 and the number of the AE sensors 4 does not necessarily coincide with each other and may be a case where the two polishing heads 34 and one AE sensor 4 constitute one set. Further, the predetermined threshold value of the AE signal from the AE sensor 4 can be set for each sensor of each stage, and a different threshold value may be set for each sensor.

Next, a preferred arrangement of the AE sensor 4 will be described with reference to Fig. As shown in FIG. 6, the AE sensor 4 is preferably disposed at a position overlapping with the glass plate G passing through the polishing head 34 in a plan view. The distance between the glass plate G and the AE sensor 4 can be made close to each other, so that the acoustic waves generated from the glass plate G can be detected without being attenuated.

It is preferable that the AE sensor 4 is disposed at the center of the glass plate G in the width direction. By arranging the AE sensor 4 at the center in the width direction, it is possible to detect the seismic wave even if any part of the glass plate G is broken. The width direction of the glass plate G means a direction orthogonal to the conveying direction of the glass plate G as seen from a plane.

It is possible to apply both the glass breakage detecting apparatus and the detection method described above to the single sheet and continuous glass sheet polishing apparatus and the polishing method of the present embodiment.

In addition, when the signal processing unit 6 determines that the glass breaks, it is preferable to provide a warning generating unit in the control unit 40 for issuing a warning. In addition, it is preferable that the polishing is stopped by the control unit (40). It is possible to judge the breakage of the glass plate G before the glass plate G is shattered by the shattering angle and to detect the breakage of the glass plate G by the signal processing unit 6, Can be stopped. The downtime caused by the damage of the polishing pad 32 and the cleaning operation can be minimized.

(Production method of glass plate)

The present invention can be applied to a glass plate manufacturing method including at least the step of forming a broken glass from a molten glass into a glass plate and cutting the glass plate to cut the glass plate. The manufacturing method of the glass plate may have a chamfering step, a boring step, a polishing step, a transporting step, and a cleaning step in addition to the cutting step. By using a liquid in these processes, it is possible to detect an elastic wave caused by breaking of the glass plate, and it is possible to judge breakage of the glass plate in the initial stage.

Particularly, in a process in which a tool and a glass plate G are in contact with each other, such as a cutting process, a chamfering process, a punching process, and a polishing process, the glass plate G is likely to be cracked. Therefore, it is preferable that the aforementioned crack detection step is provided in the cutting step, the chamfering step, the perforating step, and the polishing step. Among them, it is particularly preferable to provide a crack detection step in the polishing step.

1: glass break detector
2:
4: AE sensor
6: Signal processor
10: PLC cable
12: Preamplifier
14: Discriminator
16: Table
18: Table pad
20: Plate
22: Resin tube
24: Resin tube
26: Plate
30, 50: Polishing device
32: Polishing pad
34: Polishing head
36:
38: Rotary lifting device
40:
42: abrasive liquid supply part
44: abrasive liquid
G: Glass plate
L: liquid

Claims (14)

A detecting step of detecting an AE signal from the AE sensor in a state in which the glass plate is brought into contact with the liquid and the AE sensor is brought into contact with the liquid;
Determining a breakage of the glass plate when the AE signal exceeds a predetermined threshold value
The glass breakage detecting method comprising: The glass breaking detection method according to claim 1, wherein the determining step determines that the AE signal is broken when the AE signal continuously exceeds the threshold value. 3. The method according to claim 2, wherein the determining step determines that the AE signal is broken when the AE signal exceeds the threshold value for 150 msec successively. The glass breakage detecting method according to any one of claims 1 to 3, wherein the detecting step detects the AE signal in a frequency band in a range from 100 kHz to 200 kHz. The glass breakage detecting method according to any one of claims 1 to 4, wherein the AE sensor is electrically insulated from the liquid. A liquid supply portion for supplying liquid to the glass plate,
An AE sensor disposed at a position in contact with the liquid;
And a signal processing unit for processing the AE signal input from the AE sensor,
Wherein the signal processing unit determines that the glass plate is cracked when the AE signal exceeds a predetermined threshold value. 7. The glass breakage determination apparatus according to claim 6, wherein the signal processing section determines that the AE signal is broken when the AE signal continuously exceeds the threshold value. 8. The glass breakage determination apparatus according to claim 7, wherein the signal processing section determines that the AE signal is broken when the AE signal exceeds the threshold value continuously for 150 msec. 9. The glass breakage detecting apparatus according to any one of claims 6 to 8, having a filter for filtering the AE signal in a frequency band in a range from 100 kHz to 200 kHz. 10. The glass breakage determination device according to any one of claims 6 to 9, wherein the AE sensor is electrically insulated from the liquid. A polishing method of a glass plate polishing a surface of the glass plate by a polishing pad while supplying a polishing liquid between the polishing pad and the glass plate,
The method of polishing a glass plate according to any one of claims 1 to 5, wherein the polishing liquid is applied as the liquid. A liquid supply unit for supplying a polishing liquid to the glass plate,
A polishing apparatus for a glass plate having a polishing pad for polishing a surface of the glass plate,
The glass breakage detecting apparatus according to any one of claims 6 to 10, wherein the polishing liquid is applied as the liquid. A step of forming a glass plate from the molten glass into a plate glass, a step of cutting the glass plate by cutting the plate glass, and a crack detection step by the glass breakage detecting method according to any one of claims 1 to 5 Of the glass plate. The method of manufacturing a glass plate according to claim 13, further comprising a polishing step of polishing the surface of the glass plate, wherein the breaking detection step is provided in the polishing step.

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