JPWO2012053488A1 - Mother glass substrate drilling method and mother glass substrate - Google Patents

Abstract

The present invention provides a mother glass substrate drilling method for a plasma display panel in which a rotating drill is moved toward a mother glass substrate and a hole is formed in the mother glass substrate. A first step of detecting, a second step of stopping or decelerating the rotation of the drill after completion of drilling in the mother glass substrate, and a circumference of the hole in which the maximum radius position of the drill is preset. A third step of pulling out the drill when entering the safety area of the direction, and adjusting a stop position or a deceleration position of the drill when the maximum radius position of the drill is not within the safety area of the hole; And a mother glass substrate drilling method.

Description

  The present invention relates to a mother glass substrate drilling method and a mother glass substrate for drilling a mother glass substrate.

  For example, a plasma display panel (PDP) has a front glass substrate on which electrodes are formed, and a back surface in which red, green, and blue phosphor layers and electrodes are formed in grooves partitioned by ribs. The glass substrate and the glass substrate are opposed and integrally joined. Then, after the two glass substrates are sealed, a sealed minute gap with a sealed peripheral edge is formed, and then sealed in a state filled with a gas containing argon and neon for generating discharge.

  In the rear glass substrate, a through hole communicating with the minute gap is provided outside the display area. This through hole is used as an exhaust hole for exhausting the air in the minute gap after joining the two glass substrates in the manufacturing process, and then a gas supply hole for filling the gas in the minute gap. Used as.

  In the process of processing the through-hole, a drilling process is performed on the mother glass substrate by rotating a drilling drill having fine diamond abrasive grains on the surface at high speed (see, for example, Patent Document 1). A mother glass substrate is a glass substrate for making two or more panels from a single mother glass, so-called “multi-face drawing”. A single mother glass substrate has two exhaust holes. The above is created.

  In drilling the mother glass substrate, the first drill from below and the second drill from above are used. When the predetermined depth is reached by the first drilling from below, the first drill is pulled out first. Next, the second drill from above is further fed in the axial direction, and the first hole machined from below and the second hole machined from above are communicated. By this drilling method, chipping (hammer chipping) is prevented from occurring at the opening peripheral edge of the through hole when the drill tip penetrates the mother glass substrate.

International Publication 2008 / 044771A1

  However, as described in Patent Document 1, in the processing method in which drilling is performed from both the upper surface side and the lower surface side of the mother glass substrate using two drills, each drill is in a rotating state. There is a problem that a spiral streak defect is generated on the inner periphery of the hole when the wire is pulled out.

  In a plasma display panel manufacturing factory, after two mother glass substrates are bonded, a heat treatment (baking step) is performed in which the substrate is heated to a high temperature (for example, 500 ° C. to 600 ° C.). In the firing process of the mother glass substrate, if there is a streak defect on the inner peripheral surface of the drilled through hole, thermal stress (compressive stress, tensile stress) is applied to the mother glass substrate due to changes in temperature distribution accompanying heating and cooling. ) May act on the streak defect, and cracks starting from the streak defect may occur.

  Therefore, in view of the above circumstances, the present invention provides a mother glass substrate drilling method and a mother glass substrate that solve the above problems by defining a stop position in the drill rotation direction when the drill is pulled out after drilling. With the goal.

In order to solve the above problems, the present invention has the following means.
(1) The present invention provides a mother glass substrate drilling method for a plasma display panel in which a rotating drill is moved to a mother glass substrate side and a hole is processed in the mother glass substrate.
A first step of detecting a position of a maximum radius during rotation of the drill;
A second step of stopping or decelerating the rotation of the drill after the drilling of the mother glass substrate is completed;
When the maximum radius position of the drill is within a preset safety area in the circumferential direction of the hole, the drill is pulled out, and when the maximum radius position of the drill is not within the safety area of the hole A third step of adjusting the stop position or the deceleration position of the drill;
Have
(2) The present invention includes a fourth step in which the maximum radial position is set in accordance with the direction of application of thermal stress acting on the mother glass substrate so that the maximum radial position of the drill enters the safety region of the hole. ,
A fifth step of storing an angle range of the set rotation angle;
It is preferable to further have.
(3) The present invention determines whether or not the maximum radius position of the drill whose drilling process on the mother glass substrate is finished and whose rotation is stopped or decelerated is in the safety area of the hole. It has 6 steps,
In the sixth step, when it is determined in the sixth step that the maximum radial position of the drill is in the safety area of the hole, the drill is pulled out, and the maximum radial position of the drill is If it is determined that the hole is not in the safety area, it is preferable to adjust the stop or deceleration position of the drill.
(4) The present invention provides a mother glass substrate for a plasma display panel, in which a rotating drill moves in the axial direction and is drilled.
When the drilling process by the drill is finished and the drill is pulled out from the mother glass substrate, the streak defect generated on the inner peripheral wall of the hole is formed in a predetermined range where the tensile force due to the thermal stress of the heat treatment does not act. Preferably it is.
(5) The present invention relates to a back glass substrate for a plasma display panel in which a rotating drill moves in the axial direction and is drilled.
When the drilling process by the drill is finished and the drill is pulled out from the rear glass substrate, a streak defect generated on the inner peripheral wall of at least one of the holes is caused by a line parallel to the short side of the rear glass substrate, It is preferable that the angle formed with the line passing through the center of the hole is formed in the region of the inner peripheral surface of the hole that is within ± 50 °.

  According to the present invention, a safety region in which a tensile force due to thermal stress in the circumferential direction of the hole does not act on the periphery of the hole is set in advance, and when the maximum radial position of the drill is in the safety region, the drill is pulled out. If the maximum radial position of the drill is not within the safe area, adjust the stop position or deceleration position in the direction of drill rotation. For this reason, the drill can be pulled out from the through hole when the position of the streak defect on the inner peripheral surface of the hole is in a safe region that is not easily affected by thermal stress, and the mother starting from the streak defect in the subsequent heat treatment Breaking of the glass substrate can be prevented.

FIG. 1 is a schematic configuration diagram for explaining one embodiment of a mother glass substrate drilling apparatus according to the present invention. 2A to 2E are diagrams showing the procedure of each step of drilling. FIG. 3 is an enlarged view of the tip shape of the drill. FIG. 4 is a diagram showing a laser interferometer that measures the maximum radial position of the outer periphery of the tip of each drill. FIG. 5 is a plan view of a mother glass substrate for explaining the drilling process. FIG. 6 is a diagram showing measurement data of each rotation position of the drill and the radius of the tip outer periphery. FIG. 7A is a diagram for explaining a firing process of the mother glass substrate. FIG. 7B is a diagram for explaining the thermal stress acting on the through hole of the mother glass substrate. FIG. 8 is a flowchart for explaining a drilling control process executed by the control device.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
(Embodiment)

[Configuration of Mother Glass Substrate Drilling Machine]
FIG. 1 is a schematic configuration diagram for explaining one embodiment of a mother glass substrate drilling apparatus according to the present invention. As shown in FIG. 1, a mother glass substrate drilling device (hereinafter referred to as “drilling device”) 10 includes a clamp device 12, a lower hole processing device 14, an upper hole processing device 16, a drill measuring unit 60, The drill rotation stop position control unit 70 is configured.

  The mother glass substrate G to be punched by the punching device 10 is a mother glass substrate G used for a plasma display panel, and has a thickness of 1.8 mm to 2.8 mm manufactured by a float process, for example. Mother glass substrate G.

  The clamping device 12 of the drilling device 10 is a device that clamps the mother glass substrate G between the clamp table 18 and the upper surface of the mother glass substrate G placed on the table 20 of the drilling device 10 body. T is pressed and clamped by a clamp plate 22 formed in a ring shape. The upper hole processing device 16 processes the upper hole (first hole) into the mother glass substrate G by inserting the tip of a first drill 24 described later into the inner peripheral portion of the clamp plate 22.

  The lower hole processing device 14 is a device that processes a lower hole (second hole) having a predetermined depth on the lower surface B of the mother glass substrate G as will be described later. To prepare a prepared hole with a predetermined depth. The second drill 28 is disposed substantially perpendicular to the clamp table 18 and is attached to the rotating shaft 32 of the second motor 30 via the holder 34. The second motor 30 is attached to the lower motor attachment portion 36 through a lower linear motion guide 38 so as to be movable up and down, and is substantially perpendicular to the mother glass substrate G by a lower lifting feed screw device (not shown). Moved up and down. According to this pilot hole processing apparatus 14, the pilot hole (second hole) can be processed by pressing the second drill 28 against the lower surface B of the mother glass substrate G and applying rotation and feed. Although not shown, an insertion hole is formed in the clamp table 18, and the tip of the second drill 28 contacts the lower surface B of the mother glass substrate G through the insertion hole.

  The upper hole processing device 16 is a device that processes an upper hole on the upper surface T of the mother glass substrate G, and presses the rotating first drill 24 against the upper surface T of the mother glass substrate G to process the upper hole.

  The first drill 24 is arranged coaxially with the lower second drill 28 in the vertical direction and is arranged substantially perpendicular to the clamp table 18. The first drill 24 is mounted on the rotating shaft 44 of the first motor 42 with a holder 46. Is attached through. The first motor 42 is attached to the upper motor mounting portion 48 through an upper linear motion guide 50 so as to be movable up and down, and is moved up and down substantially perpendicularly to the mother glass substrate G by an upper lifting feed screw device (not shown). The According to the upper hole processing device 16, the upper hole can be processed by pressing the first drill 24 against the upper surface T of the mother glass substrate G and applying rotation and feed.

  The drill measurement unit 60 includes a first laser interferometer 62, a second laser interferometer 64, and a laser position detector 66. The first laser interferometer 62 measures the distance at the irradiation position by irradiating the outer periphery of the tip of the first drill 24 with laser light and receiving the reflected light from the irradiation position. The laser position detector 66 calculates the distance from the irradiation position when the first drill 24 is shifted in the rotation direction by a predetermined angle (for example, 5 ° to 10 °) from the measurement value from the first laser interferometer 62. The drill radius at the irradiation position is output as measurement data.

  The second laser interferometer 64 measures the distance at the irradiation position by irradiating the outer periphery of the tip of the second drill 28 with laser light and receiving the reflected light from the irradiation position. The laser position detector 66 calculates the distance from the irradiation position when the second drill 28 is shifted in the rotation direction by a predetermined angle (for example, 5 ° to 10 °) from the measurement value from the second laser interferometer 64. The drill radius at the irradiation position is output as measurement data.

  The drill rotation stop position control unit 70 includes a control device 72, a memory 73, a first motor rotation detector 74, a second motor rotation detector 75, a first motor driver 76, and a second motor driver 77. The control device 72 controls the lower hole processing device 14 and the upper hole processing device 16 to drill the mother glass substrate G, and adjust the drill rotation stop position when the drill is pulled out after the drilling processing. Perform control processing.

  The memory 73 includes a database that stores map data including measurement data input from the laser position detector 66 and measurement data of drill radii corresponding to the rotational direction positions of the drills 24 and 28 at predetermined angles.

  The first motor rotation detector 74 includes rotation detection means such as a rotary encoder and resolver, for example, detects the rotation angle of the rotation shaft 44 of the first motor 42, and outputs the angle detection signal to the control device 72. Similarly to the first motor rotation detector 74, the second motor rotation detector 75 includes rotation detection means such as a rotary encoder and a resolver, detects the rotation angle of the rotation shaft 32 of the second motor 30, and detects the angle. A detection signal is output to the control device 72.

  The first motor driver 76 generates a drive signal corresponding to the rotation speed or rotation angle to the first motor 42 based on the motor control signal output from the control device 72 and outputs the drive signal to the first motor 42. Similarly to the first motor driver 76, the second motor driver 77 generates a drive signal corresponding to the rotation speed or rotation angle to the second motor 30 based on the motor control signal output from the control device 72, and the second Output to the motor 30.

  The control device 72 reads each control program stored in the memory 73 and executes a drilling control process described later. That is, at the time of drilling, the control device 72 drives the first motor 42 and the second motor 30 through the motor drivers 76 and 77 at a high-speed rotation of several thousand r / min (times per minute) or more. Holes are processed in the glass substrate G. Further, when the drilling process is finished and the drills 24 and 28 are pulled out from the holes, the control device 72 stops the rotational positions of the drills 24 and 28 detected by the motor rotation detectors 74 and 75 ( It is determined which region in the circumferential direction of the hole (the maximum radius position) is located (either a safety region or a stress concentration region described later). The control device 72 then pulls the drills 24, 28 so that the drills 24, 28 are pulled out when the maximum radial position of each drill 24, 28 is in a safe region where the tensile force due to thermal stress does not act. The upper hole machining device 16 is feedback controlled.

[Drilling process with each drill]
FIG. 2 is a diagram showing the procedure of each step of drilling. As shown in FIG. 2, in this embodiment, drilling is performed according to the following procedure 1 to procedure 5. In this embodiment, the upper hole is processed and then the lower hole is processed. However, the upper hole may be processed after the lower hole is processed.
(Procedure 1: FIG. 2A) The first drill 24 is positioned on the upper surface T side with the mother glass substrate G interposed therebetween, and the second drill 28 is positioned on the lower surface B side facing the first drill 24. The horizontal mechanical error (center misalignment) between the first drill 24 and the second drill 28 is within several tens of microns.
(Procedure 2: FIG. 2B) The upper first drill 24 is lowered to start machining the upper hole 40, and the lower second drill 28 is raised to start machining the lower hole 26.
(Procedure 3: FIG. 2C) When the first drill 24 has processed the upper hole 40 to a predetermined position (depth H1) above the central portion S in the thickness direction, the upper drill 40 is processed by the first drill 24. Is stopped, the first motor 42 is raised via the upper linear motion guide 50, and the first drill 24 is pulled out from the upper hole 40. On the other hand, the processing of the prepared hole 26 by the second drill 28 continues.
(Procedure 4: FIG. 2D) The lower hole 26 and the upper hole 40 are penetrated by raising the tip of the second drill 28 to a predetermined position (depth H2). In addition, since each chamfer 122 (refer FIG. 3) is formed in the outer periphery of the edge part of the grinding part 120, each drill 24 and 28 is a predetermined position (depth H1) of the front-end | tip of the 1st drill 24 in this embodiment. ) And the tip position (depth H2) of the second drill 28 in the axial direction.
(Procedure 5: FIG. 2E) The second motor 30 is lowered through the lower linear motion guide 38 and the second drill 28 is pulled out from the through hole 5 downward. This completes the processing of the through hole 5 that becomes the exhaust hole of the mother glass substrate G. When the first drill 24 and the second drill 28 are pulled out from the through hole 5, the maximum radial position of each drill 24, 28 is in a safety region where the tensile force due to the thermal stress of the through hole 5 does not act. Each of the drills 24 and 28 is pulled out on the condition.

  At this time, the processing stop position, that is, the depth of the lower hole 26 is such that the stepped portion 6 formed in the inner peripheral portion of the through hole 5 by overlapping the lower hole 26 and the upper hole 40 is the thickness direction of the mother glass substrate G. It is determined to be located on the upper surface T side from the central portion S of the. Therefore, since the step part 6 formed in the inner peripheral part of the through-hole 5 by overlapping the lower hole 26 and the upper hole 40 is located on the upper surface T side from the central part S in the thickness direction of the mother glass substrate G, It is possible to prevent thermal cracking (cracking due to thermal stress) due to the stepped portion 6 formed in the inner peripheral portion of the through hole 5 that is an exhaust hole formed in the mother glass substrate G.

[Drill tip shape]
Here, the tip shapes of the drills 24 and 28 will be described. FIG. 3 is an enlarged view showing the tip shape of the drill. As shown in FIG. 3, each of the drills 24 and 28 has the same shape, and includes a grinding part 120 (shown with a satin pattern in FIG. 3) and a shank 130. The grinding part 120 has fine diamond abrasive grains fixed on the surface of a metal material, and is provided so as to form a substantially uniform grinding surface over the entire circumference. For example, diamond abrasive grains having a particle size of 200 to 800 mesh are preferably fixed to the grinding portion 120.

  Further, a chamfer 122 is formed on the outer peripheral side edge of the tip portion 121 of the grinding portion 120. The chamfer 122 of the tip 121 acts to suppress chipping when contacting the glass surface.

[Measurement method of the maximum radial position of each drill]
FIG. 4 is a diagram showing a laser interferometer that measures the maximum radial position of the outer periphery of the tip of each drill. As shown in FIG. 4, when the first laser interferometer 62 and the second laser interferometer 64 are replaced with a drill or when a predetermined number of mother glass substrates are punched, the drill is worn. In this case, the position of the outer peripheral portion 124 of the grinding portion 120 of each drill 24, 28 is measured for each predetermined rotation angle.

  Each of the laser interferometers 62 and 64 has an outer periphery of each grinding portion 120 from the horizontal direction when each of the drills 24 and 28 is at a height position (standby position) that is a predetermined distance away from the upper surface T and the lower surface B of the mother glass substrate G. The part 124 is irradiated with laser light, and the distance to each grinding part 120 is measured.

  The laser position detector 66 synchronizes with the rotation of the drills 24 and 28 by a predetermined angle (for example, 5 ° to 10 °) from the measured values from the laser interferometers 62 and 64. The distance from the irradiation position of the grinding part 120 is calculated, and the drill radius at the irradiation position is output as measurement data.

[Position of drilling the mother glass substrate]
FIG. 5 is a plan view of the mother substrate for explaining the drilling process of the mother glass substrate. As shown in FIG. 5, the mother glass substrate 200 on the back side is formed in a size having an area for six screens. In the mother glass substrate 200, the through hole 5 is processed as an exhaust hole outside the display area 210 (indicated by the alternate long and short dash line) of each rear glass substrate 300. The through hole 5 is formed in the vicinity of the peripheral edge of the mother substrate 200. When heat treatment (heating, cooling) is performed in the firing step, a temperature distribution is generated in the mother substrate 200, and thereby stress is generated in the peripheral portion of the through hole 5.

  The mother substrate 200 is cut along a cutting line C indicated by a broken line after the baking process described later to become six rear glass substrates.

[Measurement data]
FIG. 6 is a diagram showing measurement data of each rotation position of the drill and the radius of the tip outer periphery. As shown in FIG. 6, for example, when the outer periphery of the grinding part 120 of each drill 24, 28 is a perfect circle and there is no runout due to chucking, the measured values from the laser interferometers 62, 64 are constant. Therefore, the measured value overlaps with a reference line K0 (indicated by a two-dot chain line in FIG. 6) parallel to the horizontal axis.

  However, even if the outer periphery of the grinding part 120 of each drill 24, 28 can be manufactured to be a perfect circle, if the shank 130 is slightly tilted when chucked by the holders 34, 46, or When held eccentrically, when the drills 24 and 28 are rotated, the outer peripheral portion 124 has a portion with a large radius and a portion with a small radius. In this case, the measured values from the laser interferometers 62 and 64 are not constant, but a sine wave shape (one-dot chain line in FIG. 6) consisting of a measured value larger than the reference line K0 and a measured value smaller than the reference line K0. Or a solid line).

  Accordingly, when the runouts of the drills 24 and 28 are relatively large, the angular positions of the minimum radius A1 and the maximum radius A2 are detected at intervals of about 180 ° as shown in the graph A (indicated by the solid line in FIG. 6). . When the runouts of the drills 24 and 28 are relatively small, the angular positions of the minimum radius B1 and the maximum radius B2 are detected at intervals of about 180 ° as shown in the graph B (indicated by a dashed line in FIG. 6). The

  The control device 72 detects by calculation which angular position of the minimum radius A1, the maximum radius A2 or the minimum radius B1, and the maximum radius B2 occurs from 0 ° to 360 °, and covers the entire circumference based on the measurement data. Map data is created and stored in the database of the memory 73.

  In addition, since the maximum radius differs according to the amount of runout of each drill 24, 28, the depth of the streak defect generated on the inner peripheral surface of the through-hole 5 when drilling is performed after drilling is changed. When the depth of the streak defect exceeds a predetermined depth, the possibility of cracking due to thermal stress increases.

[The effect of thermal stress]
FIG. 7A is a diagram for explaining an example of a firing process of a mother glass substrate. As shown in FIG. 7A, in the firing step, the mother glass substrate G (mother substrate 200 shown in FIG. 5) is placed on the upper surface of the transfer base 220 and heated along the long side direction of the mother glass substrate G. Generally, it is conveyed in the furnace 230. The inside of the heating furnace 230 is heated to a high temperature of about 500 ° C. to 600 ° C. and then cooled to a predetermined temperature. As a heating method of the heating furnace 230, a method of heating the mother glass substrate G by heating the atmosphere using a heater installed on the furnace wall of the heating furnace 230 is used.

  In the heating furnace 230, the heated mother glass substrate is taken out of the heating furnace 230 and cooled when the baking process is completed.

  FIG. 7B is a diagram for explaining the thermal stress acting on the through hole of the mother glass substrate during the firing step and the cooling step. As shown in FIG. 7B, the action direction of the tensile stress Ft acting on the inner peripheral surface of the through hole 5 in the firing step and the cooling step is the long side direction (X direction) of the mother glass substrate G. The temperature distribution of the mother glass substrate in the firing process and the cooling process is such that the temperature at the center of the mother glass substrate G is high and the temperature at the periphery of the mother glass substrate G may be low. This is because the deformation is crushed in the short side direction (Y direction).

  Actually, when the temperature of the mother glass substrate G is high in the central portion of the mother glass substrate G and low in the peripheral portion of the mother glass substrate G, the temperature distribution of the mother glass substrate G depends on the tensile stress Ft acting on the inner peripheral surface of the through hole 5. It has been confirmed by experiments that the strain is maximum in the Y direction of the through-hole 5 and is minimum in the X direction.

  Further, from the experimental results, the range indicated by the region α (the central angle range of the region α = approximately ± 40 °) in FIG. 7B is a stress concentration region where distortion is relatively large due to the tensile stress Ft, and the region β (region It was found that the range indicated by the central angle range of β = approximately 100 ° is a safe region in which a relatively small strain occurs due to the tensile stress Ft. That is, in FIG. 7B, an intersection with a straight line passing through the center of the through-hole 5 and having an angle of −40 ° to + 40 ° with the short side direction (Y direction) of the mother glass substrate G in FIG. A region on the circumference of the through-hole 5 to be formed is a region α, a straight line passing through the center of the through-hole 5, and an angle formed with the long side direction (X direction) of the mother glass substrate G is −50 ° to A region on the circumference of the through hole 5 that forms an intersection with a straight line of + 50 ° is a region β. As a characteristic of glass, it is known that the pressure resistance against compressive stress is strong, but the pressure resistance against tensile stress is weak. Therefore, when a streak defect generated on the inner peripheral surface of the through-hole 5 during drill extraction occurs in the stress concentration region, cracking due to tensile stress is likely to occur.

Therefore, based on the distribution of strain due to the tensile stress Ft acting on the inner peripheral surface of the through-hole 5, a safety region in which cracks due to streak defects generated on the inner peripheral surface of the through-hole 5 are unlikely to occur and the drill pull-out is performed. A stress concentration region that is likely to crack due to the streak defect generated on the inner peripheral surface of the through hole 5 is set, and the generation of the streak defect in the stress concentration region (region α) on the inner peripheral surface of the through hole 5 is set. By preventing it, it becomes possible to prevent the crack by the said streak-like defect.
That is, it is preferable from the viewpoint of preventing cracks that the streaky defects generated on the inner peripheral surface of the through hole 5 in the mother glass substrate are present in the following regions. The position where the streak defect exists is a region of the inner peripheral surface of the through hole 5 in which an angle formed by a line parallel to the long side of the mother glass substrate and a line passing through the center of the through hole is within ± 50 °. Is more preferable, and the region of the inner peripheral surface of the through hole 5 within ± 25 ° is more preferable, and the region of the inner peripheral surface of the through hole 5 within ± 10 ° is particularly preferable.
In general, the mother glass substrate and the rear glass substrate have the positional relationship shown in FIG. For this reason, it is preferable from a viewpoint of preventing a crack that the streaky defects generated on the inner peripheral surface of the through hole 5 in the rear glass substrate exist in the following region.
The position where the streak defect exists is a region of the inner peripheral surface of the through hole 5 in which an angle formed by a line parallel to the short side of the rear glass substrate and a line passing through the center of the through hole is within ± 50 °. Is more preferable, and the region of the inner peripheral surface of the through hole 5 within ± 25 ° is more preferable, and the region of the inner peripheral surface of the through hole 5 within ± 10 ° is particularly preferable.

[Control processing of drilling]
FIG. 8 is a flowchart for explaining a drilling control process executed by the control device. In S11 of FIG. 8, when the control device 72 confirms that the mother glass substrate G is loaded on the table 20 and the clamp table 18 of the drilling device 10 and is held at a predetermined position, the control device 72 proceeds to S12, and each drill 24 , 28, the outer periphery of the grinding part 120 formed at the tip is measured. In this measurement method, as described above, the laser interferometers 62 and 64 irradiate the outer periphery of the grinding unit 120 with laser light, and the irradiation positions corresponding to the rotation angles of the respective drills 24 and 28 at predetermined angular intervals. And the measured value is stored in the memory 73.

  In the next step S13, the drills 24 and 28 are synchronized with the rotation of the drills 24 and 28 by a predetermined angle (for example, 5 ° to 10 °) from the measurement values of the laser interferometers 62 and 64. When the distance to the irradiation position is calculated and the measurement data of the drill radius at the irradiation position is obtained, for example, as shown in FIG. 6, a data map based on the measurement data of the drill radius corresponding to the rotation angle of each drill Is stored in the memory 73. That is, the process from S12 to here is the first step of detecting the position of the maximum radius when the drill rotates. Furthermore, referring to the range of the safety region in the circumferential direction of the hole 5 shown in FIG. 7B described above, based on the data map, the maximum radial position of the drill at the time of processing is a through hole formed in the mother glass. The maximum radial position of the drill is set in accordance with the direction of application of tensile stress due to thermal stress acting on the mother glass substrate G so as to enter the safety region (fourth step).

  Subsequently, the process proceeds to S14, in which the rotation angle (circumferential address of the maximum radial position) of the set maximum radial position of each drill 24, 28 is extracted from the data map and stored in the memory 73 (fifth step). ). In next S15, the drills 24 and 28 are fed to the mother glass substrate G side to start drilling (see procedure 2 in FIG. 2B).

  When the drilling of the mother glass substrate G by the drills 24 and 28 is started, it is checked in S16 whether or not the depth of the upper hole 40 on the upper surface side has reached a preset processing depth H1. In S16, after the depth of the upper hole 40 reaches the processing depth H1, the process proceeds to S17, and the rotation of the first drill 24 is stopped (second step). In addition, after the front-end | tip of the 1st drill 24 reaches the predetermined depth of the mother glass substrate G, you may stop rotation of the 1st drill 24, or the rotational speed of the 1st drill 24 is 1r / min-5r. You may decelerate to low speed rotation of / min.

  In the next S18, the stop angle position in the rotation direction of the rotating shaft 44 is read by the detection signal of the first motor rotation detector 74. Subsequently, the process proceeds to S19, where the stop angle position (circumferential address of the stop position) of the rotating shaft 44 detected by the first motor rotation detector 74, that is, the stop angle position of the first drill 24 is stored in the memory 73 described above. The maximum radius position (maximum radius circumferential address) of the first drill 24 is within the range of the safety area (area β) of the inner peripheral surface of the through hole 5 described above by collating with the data map stored in the database. Is checked (sixth step).

  In S19, when the maximum radial position of the first drill 24 is within the range of the stress concentration region (region α) on the inner peripheral surface of the through hole 5 described above (in the case of NO), the process proceeds to S20, and the first For example, the rotation shaft 44 of the first motor 42 to which the drill 24 is directly connected is rotated by an angle of 80 ° (third step). The rotation angle at this time is not limited to 80 °, and if the central angle range of the region α is larger than 40 °, the maximum radius position of the first drill 24 is moved to the safety region (region β). Can do.

  Thereafter, the processes of S17 to S19 described above are repeated. In S19, when the rotation of the first motor 42 is stopped, the maximum radial position of the first drill 24 is within the range of the safety region (region β) on the inner peripheral surface of the through hole 5 described above. In the case (YES), the process proceeds to S21 without performing the motor control process in S20. In S21, the first motor 42 is raised through the upper linear motion guide 50, and the first drill 24 is pulled upward from the upper hole 40 of the mother glass substrate G (third step: refer to procedure 3 in FIG. 2C). Thereby, it is possible to prevent the occurrence of a streak defect when the first drill 24 is pulled out in the stress concentration region (region α) on the inner peripheral surface of the through hole 5. The first drill 24 is preferably pulled out at a speed of 10 mm / s to 40 mm / s, for example.

  In the next S22, it is checked whether or not the depth of the lower hole 26 on the lower surface side has reached a preset processing depth H2. In S22, after the depth of the lower hole 26 reaches the processing depth H2 (see procedure 4 in FIG. 2D), the process proceeds to S23, and the rotation of the second drill 28 is stopped (second process). In addition, after the front-end | tip of the 2nd drill 28 reaches the predetermined depth of the mother glass substrate G, you may stop the rotation of the 2nd drill 28, or the rotational speed of the 2nd drill 28 is 1r / min-5r. You may decelerate to low speed rotation of / min.

  In the next S24, the stop angle position of the rotating shaft 32 is read by the detection signal of the second motor rotation detector 75. In S25, the stop angle position of the rotating shaft 32 detected by the second motor rotation detector 75, that is, the stop angle position of the second drill 28 is stored in the data map stored in the database of the memory 73 described above. By collating, it is checked whether or not the maximum radial position of the second drill 28 is within the range of the safety region (region β) of the inner peripheral surface of the through hole 5 described above (sixth step).

  In S25, when the maximum radial position of the second drill 28 is within the range of the stress concentration region (region α) on the inner peripheral surface of the through hole 5 described above (in the case of NO), the process proceeds to S26, and the second The rotary shaft 32 of the second motor 30 to which the drill 28 is directly connected is rotated by, for example, 80 ° (third step). Note that the rotation angle at this time is not limited to 80 °, and if the central angle range of the region α is larger than 40 °, the maximum radius position of the second drill 28 is moved to the safety region (region β). Can do.

  Thereafter, the processes of S23 to S25 described above are repeated. In S25, when the rotation of the second motor 30 is stopped, the maximum radial position of the second drill 28 is within the range of the safety region (region β) of the inner peripheral surface of the through hole 5 described above. In the case (YES), the process proceeds to S27 without performing the motor control process in S26. In S27, the second motor 30 is lowered via the lower linear motion guide 38, and the second drill 28 is pulled downward from the hole 26 of the mother glass substrate G (third step: refer to procedure 5 in FIG. 2E). Thereby, it is possible to prevent a streak defect when pulling out the second drill 28 from occurring in the stress concentration region (region α) on the inner peripheral surface of the through hole 5. The second drill 28 is preferably pulled out at a speed of 10 mm / s to 40 mm / s, for example.

  In the next S28, it is checked whether or not all of the through holes 5 have been processed. For example, as shown in FIG. 5 described above, in the case of the mother substrate 200 corresponding to six screen sizes, the through holes 5 are processed at six locations. When the number of processed through holes 5 is less than 6 (in the case of NO), the control processing of S15 to S28 is repeated until the through holes 5 are processed into 6 locations.

  If all the through holes 5 have been processed in S28 (YES), the process proceeds to S29, and the mother glass substrate G in which the drilling has been completed is replaced with the table 20 and the clamp table of the drilling apparatus 10. 18 and the unprocessed new mother glass substrate 200 is held on the table 20 and the clamp table 18. The replacement work of the mother glass substrate 200 is performed by a mother glass substrate transfer robot.

  In next S30, it is checked whether or not the drill replacement time defined by the number of times of drill use or the drilling time has been reached. In S30, when each drill 24, 28 currently used has reached the drill replacement time (in the case of YES), the replacement work of each drill 24, 28 is performed.

  In S31, the map data of the drills 24 and 28 stored in the memory 73 is deleted. When the exchanging work of the drills 24 and 28 is performed, the next time, the control process of S11 is performed.

  In this way, the maximum radial position of each drill 24, 28 is measured, the rotation of each drill 24, 28 is stopped after drilling, and the stop position (from the detection signal of each motor rotation detector 74, 75) ( When the circumferential direction address) is within the safety region (region β) of the inner peripheral surface of the through hole 5, the drills 24, 28 are pulled out by pulling the drills 24, 28 from the through hole 5. It is possible to prevent the streak-like defect from occurring in the stress concentration region (region α) on the inner peripheral surface of the through hole 5 and to prevent the mother glass substrate G from being cracked due to thermal stress in the firing process.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications and changes can be made without departing from the spirit and scope of the invention. .
This application is based on Japanese Patent Application No. 2010-235885 filed on Oct. 20, 2010, the contents of which are incorporated herein by reference.

DESCRIPTION OF SYMBOLS 10 Mother glass substrate drilling apparatus 12 Clamp apparatus 14 Pilot hole processing apparatus 16 Upper hole processing apparatus 18 Clamp table 20 Table 22 Clamp plate 24 First drill 26 Lower hole 28 Second drill 30 Second motors 32 and 44 Rotating shaft 34 , 46 Holder 36 Lower motor mounting portion 38 Lower linear motion guide 40 Upper hole 42 First motor 48 Upper motor mounting portion 50 Upper linear motion guide 60 Drill measurement unit 62 First laser interferometer 64 Second laser interferometer 66 Laser Position detector 70 Drill rotation stop position control unit 72 Control device 73 Memory 74 First motor rotation detector 75 Second motor rotation detector 76 First motor driver 77 Second motor driver 120 Grinding unit 121 Tip portion 122 Chamfer 124 Outer peripheral portion 130 Shank 200 Mother glass substrate 210 Display area 220 Transport Base 230 heating furnace

Claims (5)

In the mother glass substrate drilling method for a plasma display panel that moves the rotating drill to the mother glass substrate side and processes holes in the mother glass substrate,
A first step of detecting a position of a maximum radius during rotation of the drill;
A second step of stopping or decelerating the rotation of the drill after the drilling of the mother glass substrate is completed;
When the maximum radius position of the drill is within a preset safety area in the circumferential direction of the hole, the drill is pulled out, and when the maximum radius position of the drill is not within the safety area of the hole A third step of adjusting the stop position or the deceleration position of the drill;
A mother glass substrate drilling method. A fourth step of setting the maximum radial position according to the direction of action of thermal stress acting on the mother glass substrate so that the maximum radial position of the drill enters the safety region of the hole;
A fifth step of storing a range of the set maximum radius position;
The mother glass substrate drilling method according to claim 1, further comprising: And further comprising a sixth step of determining whether or not the maximum radius position of the drill whose drilling process on the mother glass substrate is finished and whose rotation has been stopped or decelerated is within the safety region of the hole,
In the sixth step, when it is determined in the sixth step that the maximum radial position of the drill is in the safety area of the hole, the drill is pulled out, and the maximum radial position of the drill is The mother glass substrate drilling method according to claim 1 or 2, wherein when it is determined that the hole is not in the safety area, the stop or deceleration position of the drill is adjusted. In the mother glass substrate for the plasma display panel, where the rotating drill moved in the axial direction and drilled,
When the drilling process by the drill is finished and the drill is pulled out from the mother glass substrate, the streak defect generated on the inner peripheral wall of the hole is formed in a predetermined range where the tensile force due to the thermal stress of the heat treatment does not act. A mother glass substrate. In the back glass substrate for the plasma display panel, the rotating drill moved in the axial direction and drilled,
When the drilling process by the drill is finished and the drill is pulled out from the rear glass substrate, a streak defect generated on the inner peripheral wall of at least one of the holes is caused by a line parallel to the short side of the rear glass substrate, A back glass substrate formed in a region of the inner peripheral surface of the hole, the angle formed with a line passing through the center of the hole being within ± 50 °.

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