JP2011111370A - Apparatus and method for manufacturing glass plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To substantially prevent the remaining of fine chips by chipping in an opening of an end face of a glass plate in a step of boring the glass plate and to accurately form a through-hole. <P>SOLUTION: A preceding drill 1 is allowed to penetrate under cutting into a glass plate 3 in the thickness direction from the lower end face side to form a bottomed hole 31, the preceding drill 1 is retreated, and a following drill 2 is allowed to penetrate coaxially with the preceding drill 1 under cutting from the upper end face side of the glass plate 3 to form a through-hole 34 in the glass plate 3. The at least one drill 1 is composed of a body part 11 having a uniform outer diameter along the axial direction, a small diameter part 12 positioned on the drill base end side of the body part 11 and having a smaller outer diameter than the body part 11, and a connection part 13 connecting the body part 11 and the small diameter part 12, and cutting ability is provided to the part from the tip of the drill 1 to at least the body part 11 side of the connection part 13. The drill 1 used in the boring step is configured such that in a state in which the drill 1 is allowed to penetrate to the deepest part, the connection part 13 reaches a thickness-direction inner side of the glass plate 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a glass plate manufacturing apparatus and a manufacturing method therefor, and more specifically, a through hole is formed in a glass plate by allowing separate drills to penetrate from the upper surface side and the lower surface side of the glass plate coaxially with cutting. Related to technology.

  As is well known, some glass substrates used for flat panel displays such as plasma display (PDP), field emission display (FED), and electroluminescence display (ELD) are used for exhaust and gas filling in the panel. For this purpose, there is one that forms a through hole.

  For example, in the case of a PDP, it is necessary to enclose a gas such as Xe or Ar in the space between the front plate and the back plate in order to generate an effective plasma discharge. In addition, through holes having a diameter of about several millimeters for discharging air and filling the gas are formed at one or a plurality of locations. Also, in the case of FED, since the space between the front plate and the back plate needs to be high vacuum, one or more penetrations are made in the peripheral portion or corner portion of the back plate in the same manner as the glass substrate for PDP. A hole is formed.

  By the way, in the manufacturing process of PDP and some FED, in order to form a transparent electrode, fluorescent substance, a rib, and other elements on each glass substrate, heat processing processes, such as baking, are provided. In this heat treatment step, if a defect such as a chip or a micro crack exists in the glass substrate, stress concentration occurs in the chip or the micro crack during heating or cooling. And the situation where a glass substrate breaks starting from these stress concentration parts may be caused. This type of breakage originates from the exhaust holes (through holes) on the back plate, and more precisely, chips or microcracks that exist on the inner peripheral surface of the through holes or on the end surfaces of the glass substrate (openings) Therefore, it is important to remove these defective portions as much as possible to improve the surface properties of the through hole and its periphery.

  As means for solving the above problem, for example, in Patent Document 1 below, the lower drill is moved from the lower surface of the glass plate to the middle position in the thickness direction of the glass plate with cutting, and then the lower drill is moved backward. Then, the manufacturing apparatus of the glass plate comprised so that a through-hole may be formed by letting an upper drill penetrate | invade coaxially with a lower drill with cutting from the upper surface of a glass plate is disclosed.

JP 2008-137354 A

  Thus, although there is a defect such as a chip ordinarily in the inner peripheral surface of the through-hole formed in the glass plate and its opening, by performing the punching process with the manufacturing apparatus described in Patent Document 1, In particular, it was possible to prevent the occurrence of large cracks or microcracks that would be a problem. Recently, however, the increase in the size of glass substrates for flat panel displays has resulted in greater mechanical and thermal loads than ever during processing as well as during handling. Has come to occur. Since this type of stress increases at non-uniform locations on the glass plate as described above (stress concentration occurs), even if it is a fine chip (also called chipping) of a size that has not been a problem until now. If it remains around the opening of the through hole, the glass plate may be damaged.

  Here, in the manufacturing apparatus described in Patent Document 1, when the drill finally forms the through hole, the opening of the through hole on the upper and lower one end surface (end surface in the drill penetration direction) side of the glass plate The purpose of this is to prevent the generation of relatively large burrs, and is not intended to prevent the occurrence of fine burrs. In addition, since the fine chip may occur in the opening portion of the through hole on the upper or lower end surface (end surface on the front side in the penetrating direction) side of the glass plate, the manufacturing apparatus disclosed in Patent Document 1 is used as it is. As a result, it is difficult to effectively prevent the minute chip from remaining in the opening of the through hole or in the vicinity thereof.

  In view of the above circumstances, in the present invention, in the perforating process of the glass plate, it is possible to prevent as much as possible a situation in which fine chips such as chipping remain in the opening of the end surface of the glass plate, and to accurately form the through hole. Is a technical issue.

  The solution to the above problem is achieved by the glass plate manufacturing apparatus according to the present invention. That is, this glass plate manufacturing apparatus, with cutting from one end surface side of the glass plate, penetrates the preceding drill in the thickness direction to form a bottomed hole, and then retracts the preceding drill. In a glass plate manufacturing apparatus configured to form a through-hole in a glass plate by allowing a subsequent drill to penetrate coaxially with a preceding drill with cutting from the other end surface side, at least one of the drills has an axial direction A body portion having a constant outer diameter, a small diameter portion located on the drill base end side of the body portion and having a smaller outer diameter than the body portion, and a connecting portion for connecting the body portion and the small diameter portion. In addition, when cutting ability is given to the part from the tip of one drill to at least the body side of the joint, and at least one part of the joint is made of glass, Thickness of board It characterized with that it is configured so as to reach the inside.

  This configuration has been created based on the inventors' new knowledge regarding the occurrence of cracks. That is, when the drill that has finished the drilling operation is retracted, the present inventors accurately form the end surface on the rear side of the glass plate (end surface on the drilling start side) when turning the forward / backward direction from forward to backward. It has been found that the above-mentioned fine cracks are generated at the opening portion of the hole (bottomed hole or through-hole) to be formed or the periphery thereof. And based on this knowledge, while providing the connection part of the trunk | drum and small diameter part of a drill, it came to provide grinding capability to this connection part. Therefore, according to the above manufacturing apparatus, when the drill turns from advance to retreat, the largest diameter barrel is on the inner side in the thickness direction of the glass plate. It is not necessary to make the part and the drill contact. As a result, it is difficult to transmit the unstable driving force of the drill when moving from forward to backward to the opening of the hole, and generation of fine chipping can be suppressed. In addition, since the cutting ability is given not only to the body part but also to the joint part, even when the drill continues to retreat and the opening part of the hole formed in the end surface of the glass plate comes into contact. The contact portion can be smoothly removed by cutting at the connecting portion, and it is possible to prevent, as much as possible, a situation in which fine debris remains in the opening or its periphery after the end of the drilling step. Of course, since this drill is provided with grinding ability at the body portion which is the maximum diameter portion over a predetermined axial dimension, for example, when the drill having the above shape is used as the subsequent drill, the drill is pulled out (retracted). By doing so, it is possible to accurately form the through hole over the entire length while leaving no fine chipping in the opening.

  Here, the connecting portion may have a shape that gradually decreases in diameter from the trunk portion toward the drill base end side. Further, in this case, the connecting portion may have a shape that decreases in a taper shape.

  In this way, by forming the joint part into a shape that gradually decreases in diameter, even when the opening part and the joint part come into contact with each other when the drill moves backward, the cutting is transmitted from the drill (joint part) to the opening part. The power will increase gradually. Thereby, generation | occurrence | production of defects, such as a fine chip, can be suppressed effectively. In addition, by forming the connecting portion into a tapered shape, it is possible to suppress the generation of fine chips and finish the opening more smoothly.

  Further, the axial dimension of the body part may be set to be 0.2 times or more and 0.5 times or less of the axial dimension from the tip of one drill to the end part on the small diameter part side of the connecting part.

  The dimensional relationship is determined in this way for the following reason. In other words, if the axial dimension of the body is less than 0.2 times, the contact area between the drill and the machining surface (here, the inner peripheral surface of the through hole) becomes too small, and wear of the drill progresses early. It is because there is a possibility of doing. In addition, if the ratio exceeds 0.5 times, the contact area between the drill and the processed surface becomes excessive, and there is a risk that defects such as burns may occur on the processed surface due to frictional resistance generated between the contact surfaces. From the above, by setting the axial dimension of the barrel within the above range, the cutting performance and durability of the glass plate perforation process can be imparted to the drill, and the processing accuracy of the inner peripheral surface and its opening can also be improved. An excellent through hole can be formed.

  Moreover, the drill which comprises the above form may be integrally provided with the enlarged diameter part which is located in the drill front end side of a trunk | drum, and gradually expands as it goes to a trunk | drum.

  If drilling is performed when the centering of the drill is not performed correctly (especially when the core drill is centered), uneven force acts on the inner peripheral surface of the hole due to the centering of the drill. It becomes difficult to form excellent through holes. This tendency is particularly remarkable at the opening end of the hole or in the vicinity thereof. In this regard, by providing the enlarged diameter portion on the drill tip side of the barrel portion as described above, the drill is guided in a direction that suppresses center runout, so unnecessary force acting on or near the opening end of the hole is reduced. can do. Further, by suppressing the core runout, it is possible to prevent the occurrence of fine chipping with a higher probability by avoiding the drill from coming into contact with the opening of the hole when the drill starts to retract. Said guidance function acts more effectively by making a diameter-expanded part into a taper shape.

  Moreover, when one drill is a preceding drill, the axial direction dimension from the front-end | tip to the edge part by the side of the connection part of a trunk | drum may be smaller than the thickness dimension of a glass plate.

  As for the following drill, since the glass plate is completely penetrated, the maximum penetration position should be adjusted so that the connecting part reaches the inner side in the thickness direction of the glass plate when the drill penetrates deepest as described above. However, the preceding drill needs to be stopped at an intermediate position in the thickness direction without penetrating the glass plate. Therefore, by setting the axial dimension of a predetermined part of the drill (body, joint, etc.) so as to satisfy the dimensional relationship with the glass plate, the thickness of the glass plate can be ensured when the drill starts to retract. It can be located inside the direction.

  Various drills can be used as one or both of the drills according to the above description as long as they have the above-described shape or dimensional relationship, but a core drill having a hollow cutting edge shape is adopted from the viewpoint of processing speed and production efficiency. You can also. As a core drill, a surface type in which cutting abrasive grains such as diamond abrasive grains are fixed to a surface of a cylindrical base metal (in the present invention, a body part or a joint part) with an appropriate bonding material, or the abrasive grains There is an implement type using a chip formed by dispersing and arranging in a metal bond. Here, for example, when adopting a surface type core drill having a large abrasive grain protrusion and excellent machinability, the outer diameter of the body formed by fixing the abrasive grains for cutting on the surface and the outer diameter minimum value of the joint portion and May be set to be twice or more the average particle size of the abrasive grains.

  Thus, when using a core drill, by assuming that the maximum outer diameter difference between the body portion and the connecting portion is twice or more the average particle size of the abrasive grains for cutting, for example, assuming a slight runout, Even when the entire region of the joint portion enters the inside of the hole cut and formed in the body portion, the opening of this hole and the abrasive grains fixed to the end portion on the small diameter side of the joint portion come into contact with each other. There is nothing. Therefore, when the entire area of the connecting portion reaches the inside of the hole with the drill penetrating deepest as described above, the connecting portion (or small diameter portion) interferes with the opening when the drill starts to retract. The situation can be avoided reliably.

  Moreover, the solution of the said subject is achieved also by the manufacturing method of the glass plate which concerns on this invention. That is, this glass plate manufacturing method involves cutting the front drill in the thickness direction with cutting from one end surface side of the glass plate to form a bottomed hole, and then retracting the preceding drill. In a glass plate manufacturing method including a drilling step in which a through-hole is formed in a glass plate by causing a subsequent drill to penetrate coaxially with a preceding drill with cutting from the other end surface side, along at least one of the drills along the axial direction. A body portion having a constant outer diameter, a small-diameter portion located on the drill base end side of the body portion and having a smaller outer diameter than the body portion, and a connecting portion that connects the body portion and the small-diameter portion, In the drilling process, a part that has cutting ability at least from the tip of the drill to the body side of the joint is used in the drilling process. To the inside in the thickness direction It characterized with that the way.

  The manufacturing method described above also has the same technical features as the manufacturing apparatus described at the beginning of this section, so that the same operational effects as the operational effects of the manufacturing apparatus can be obtained.

  Moreover, it is preferable that the glass plate manufactured by the above manufacturing apparatus and manufacturing method is a glass substrate for flat panel displays.

  By doing so, it is possible to effectively avoid a situation in which the glass substrate is damaged starting from the through hole (exhaust hole), particularly the opening, in the heat treatment step when manufacturing the flat panel display.

  As described above, according to the glass plate manufacturing apparatus and the manufacturing method thereof according to the present invention, in the glass plate perforation process, it is possible to prevent the occurrence of minute chips such as chipping at the opening of the glass plate end surface. In this way, the through hole can be formed with high accuracy.

It is sectional drawing which shows the principal part of the precedent drill and subsequent drill which are the main components of the manufacturing apparatus of the glass plate which concerns on one Embodiment of this invention. It is the top view which looked at the drill shown in FIG. 1 from the front end side. (A)-(d) is sectional drawing which shows the outline | summary of the drilling operation | work by a preceding drill among the drilling processes in the manufacturing method of the glass plate which concerns on one Embodiment of this invention in order of time series, respectively. It is a principal part expanded sectional view for demonstrating the effect | action with respect to the glass plate at the time of retracting | retreating a preceding drill. (A)-(d) is sectional drawing which shows the outline | summary of the drilling operation | work by a subsequent drill among the punching processes in the manufacturing method of the glass plate which concerns on one Embodiment of this invention in order of a time series, respectively.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a case where through holes as exhaust holes are formed at corners of a glass substrate for PDP will be described as an example.

  The glass plate manufacturing apparatus according to one embodiment of the present invention has, as shown in FIG. 3A, for example, a preceding drill 1 disposed on the lower side of the glass plate 3 and the preceding drill 1 having axial positions relative to each other. A trailing drill 2 disposed on the upper side of the glass plate 3 in a matched state is provided as a main component. The preceding drill 1 and the succeeding drill 2 are configured to be able to move up and down and rotate independently of each other. Note that the “vertical” direction here is merely defined for easy understanding of the positional relationship between elements in each drawing. Therefore, it does not specify the installation direction and usage of the glass plate manufacturing apparatus described below, or the installation direction of the glass plate in the manufacturing apparatus.

  As shown in FIG. 1, the preceding drill 1 includes a barrel portion 11 that is the maximum outer diameter portion, a small-diameter portion 12 that is located on the drill base end side of the barrel portion 11 and has a smaller outer diameter than the barrel portion 11, and a barrel The connecting portion 13 that connects the portion 11 and the small diameter portion 12 is integrally provided. In this embodiment, the leading drill 1 is a core drill and generally has a cylindrical shape as shown in FIGS. 1 and 2. Further, the preceding drill 1 is integrally provided with an enlarged diameter portion 14 that is located on the drill tip side of the trunk portion 11 and that has a shape that increases in diameter in a tapered shape as it approaches the trunk portion 11. As shown in FIG. 1, the connecting portion 13 also has a shape that decreases in a taper shape as the distance from the body portion 11 increases. Connected to. Similarly, the connecting portion 13 is smoothly connected to the small diameter portion 12 having a constant outer diameter via the cross section R at the upper end thereof.

Next, the dimensional relationship between each element will be described. First, the axial dimension L ₁ (see FIG. 1) from the tip of the preceding drill 1 to the end of the trunk portion 11 on the connecting portion 13 side is the thickness dimension t (FIG. 3 (a) of the glass plate 3 to be cut. (See)). In this embodiment, as shown in FIG. 3C, which will be described later, in the state where the leading drill 1 has entered from the lower end surface side of the glass plate 3 deeply with cutting (to the side closer to the upper end surface), it is connected. The axial dimension L ₁ is set so that the entire region of the portion 13 is located between the upper and lower end surfaces of the glass plate 3.

Further, 0 from the leading edge of the preceding drill 1 when the axial dimension of the end portion of the small diameter portion 12 side of the connecting portion 13 and the L _2, the axial dimension d ₁ of the body portion 11 of the axial dimension L _2. It is set to be 2 times or more and 0.5 times or less. Similarly, the axial dimension d _{2 of the} enlarged diameter portion 14 is set to be 0.2 times or more and 0.4 times or less of the axial dimension L ₂ .

  Similarly to the preceding drill 1, the subsequent drill 2 also has a body portion 21, a small diameter portion 22, a connecting portion 23, and an enlarged diameter portion 24, and the dimensional relationship is also the same.

  The preceding drill 1 and the following drill 2 having the above-described configuration are, for example, the surface of a metal main body formed by integrating the body portions 11 and 21, the small diameter portions 12 and 22, the connecting portions 13 and 23, and the enlarged diameter portions 14 and 24. Is formed by adhering abrasive grains (not shown) such as diamond abrasive grains and CBN abrasive grains with an appropriate bonding material.

  Next, a procedure for forming a through hole in a glass plate using the preceding drill 1 and the succeeding drill 2 will be described with reference to FIGS.

  First, as shown in FIG. 3A, the preceding drill 1 is moved from the lower end surface side of the glass plate 3 by raising the preceding drill 1 disposed below the glass plate 3 in a horizontal posture with rotation. It penetrates in the thickness direction with cutting. In this embodiment, as shown in FIG. 3 (b), the distal end (smaller diameter side) of the enlarged diameter portion 14 provided at the drill distal end of the preceding drill 1 is advanced to enter the inner side in the thickness direction of the glass plate 3. . At this time, the preceding drill 1 may enter the glass plate 3 while supplying the cutting fluid to the entry location of the preceding drill 1. You may make it penetrate | invade, supplying coolant, such as water, to the advance drill 1. FIG.

  And as shown in FIG.3 (c), when the preceding drill 1 penetrate | invades to the axial direction intermediate position of the glass plate 3 in the state which left only the predetermined thickness dimension at the upper end surface side of the glass plate 3, it precedes. The ascent of the drill 1 is stopped. At this stage, as shown in FIG. 3 (c), not only the diameter-expanded portion 14 and the body portion 11 of the preceding drill 1 but also at least a part of the connecting portion 13 is inside in the thickness direction of the glass plate 3 (upper end surface and lower end surface). Between). In this embodiment, the entire region of the connecting portion 13 is located inside the bottomed hole 31 formed in the glass plate 3 by the preceding drill 1. From this state, the descending operation of the preceding drill 1 is started, and as shown in FIG. 3D, the preceding drill 1 is extracted from the glass plate 3 and moved to the retracted position shown in FIG. As a result, the glass plate 3 is in a state in which a bottomed hole 31 in a non-penetrating state that is open only at the bottom is formed. In this embodiment, a substantially cylindrical bottomed hole 31 is formed following the shape of the preceding drill 1, and a substantially columnar core 32 remains in the center thereof.

  Further, when the descending operation is started from the position where the preceding drill 1 enters the side closest to the upper end surface of the glass plate 3, as shown in FIG. 11 is located inside the bottomed hole 31 formed in the glass plate 3. Further, the opening 33 located below the bottomed hole 31 is not in contact with any part (the trunk 11, the connecting part 13, the small diameter part 12) of the preceding drill 1. Therefore, when the preceding drill 1 shifts from the ascending operation to the descending operation as described above, the load caused by the descending operation of the preceding drill 1, particularly, the load caused by the unstable operation when turning from ascending to descending To the opening 33. As a result, it is possible to suppress as much as possible the occurrence of fine chipping on the inner peripheral surface of the opening 33 or the periphery thereof (such as the end surface portion).

  Further, as shown in FIG. 4, when the leading drill 1 is lowered, it may be possible that the opening 33 and the joint portion 13 of the leading drill 1 come into contact with each other due to the slight centering of the drill. Also in this case, the connecting portion 13 has a tapered shape, and grinding ability such as diamond abrasive grains is fixed to the outer peripheral surface of the connecting portion 13 so that the connecting portion 13 has a grinding ability. The surface can be cut smoothly. For this reason, even if fine cracks have already occurred in the opening 33 until the joint 13 and the opening 33 interfere with each other, the outer periphery that becomes the grinding surface of the joint 13 The surface property of the opening 33 can be improved by scraping off the surface (or the section R between the trunk portion 11 and the connecting portion 13).

  Next, as shown in FIG. 5 (a), the trailing drill 2 disposed above the glass plate 3 is lowered with rotation to cut the trailing drill 2 from the upper end surface side of the glass plate 3. Intrusions in the thickness direction. In this case, since the trailing drill 2 is arranged in a state in which the preceding drill 1 previously drilled and its axis are aligned, the axis of the bottomed hole 31 already formed in the glass plate 3 A drilling operation to be described later is performed in a state where the axis of the subsequent drill 2 coincides.

  Then, by continuing to lower the trailing drill 2 and further entering the glass plate 3, as shown in FIG. 5 (b), all the portions that become the bottom of the bottomed hole 31 formed by the preceding drill 1 are all. Scraped off. Thereby, the core 32 is also removed (separated from the glass plate 3 main body and dropped), and a through hole 34 having a constant inner diameter is formed. Then, from the state in which the trailing drill 2 is lowered to a position where all of the body portion 21 of the trailing drill 2 enters the inside of the through hole 34 (see FIG. 5C), the rising operation of the trailing drill 2 is performed. As shown in FIG. 5D, the subsequent drill 2 is extracted from the glass plate 3 and moved to the retracted position shown in FIG. As a result, the glass plate 3 is formed with through holes 34 having openings 33 and 35 on both end faces. Further, since the inner peripheral surface of the through hole 34 is ground by the body portion 11 of the preceding drill 1 and the body portion 21 of the subsequent drill 2 over the entire region in the axial direction, the inner peripheral surface of the through hole 34 is high. Finished with precision.

  Further, when the trailing drill 2 descends (intrudes) to the deepest position and then starts to move up, as shown in FIG. 5 (c), the body portion 21 serving as the maximum outer diameter portion of the trailing drill 2 is All are located below the opening 35 of the through-hole 34 formed in the upper end surface of the glass plate 3. At this time, the opening 35 is not in contact with any part of the subsequent drill 2 including the body 21. Therefore, when the succeeding drill 2 shifts from the descending operation to the ascending operation as described above, the load caused by the descending operation of the succeeding drill 2, particularly, the descending (intrusion operation) is changed to the ascending (drawing operation). It is not necessary to apply a load due to unstable operation at the time to the opening 35. As a result, it is possible to suppress the occurrence of minute chipping on the inner peripheral surface of the opening 35 or the periphery thereof (such as the end surface portion) as much as possible, and to form the highly accurate through hole 34.

  As mentioned above, although one Embodiment of the manufacturing apparatus of the glass plate which concerns on this invention, and its manufacturing method was described, these are not limited to the form of the said illustration, Arbitrary forms can be taken within the scope of the present invention. .

  For example, in the above-described embodiment, the case where the outer peripheral surfaces of the connecting portions 13 and 23 are tapered is illustrated, but it is of course possible to adopt other forms. For example, by forming the cross-sections of the connecting portions 13 and 23 with a curved surface of any one of the concave and convex portions, it is possible to form the connecting portions 13 and 23 so as to gradually reduce the diameter toward the small diameter portion 12.

  The diameter-expanded portion 14 does not necessarily have to be integrally formed. For example, although not illustrated, the tip end surfaces of the drills 1 and 2 and the body portions 11 and 21 are smoothly connected via the cross-section R portion. Also good. Alternatively, as each of the drills 1 and 2, a drill other than the core drill, for example, various solid drills having a cutting blade on the tip surface may be used.

  Moreover, although the case where the preceding drill 1 and the following drill 2 were made into the same shape and the same dimension was illustrated in the said embodiment, of course, it is also possible to make the said shape and dimension different. For example, the outer diameter dimension of the succeeding drill 2 (the outer diameter dimension of the body portion 21) remains the same as that of the preceding drill 1, and the small diameter portion 22 has a different diameter with respect to the small diameter portion 12 of the preceding drill 1. Accordingly, the taper angles of the connecting portions 13 and 23 may be made different.

  Further, in the above-described embodiment, as shown in FIG. 5C, the subsequent drill 2 extends through the entire length in the axial direction of the through hole 34, and the body portion 21 and the enlarged diameter portion 24 all enter the inside of the through hole 34. Although the case where it started to the ascending operation from the state lowered to the position where it is moved is illustrated, it is of course possible to use the glass plate manufacturing apparatus according to the present invention for other drilling processes. For example, although illustration is omitted, the ascending operation of the succeeding drill 2 from a state in which the succeeding drill 2 has entered (lowered) to a position where a part of the distal end side of the enlarged diameter portion 24 protrudes downward from the through hole 34. May be started and the subsequent drill 2 may be pulled out from the through hole 34.

  In the above description, the present invention is applied to the case where a through hole as an exhaust hole is formed in a glass substrate for PDP. However, in the case where a through hole is formed in a glass substrate for FED or ELD in addition to this, In addition, the present invention can be applied to the same manner as well, and when it is necessary to form a through hole in the glass plate in which generation of fine cracks is a problem, the present invention can be applied to all of them. It is.

  In order to confirm the effect of the present invention, the following tests and examinations were conducted. Regarding the glass plate manufacturing apparatus (Example) provided with the preceding drill and the subsequent drill according to the present invention and the glass plate manufacturing apparatus (Comparative Example) provided with the conventional drill, common items will be described first. . First, 20 glass substrates for PDP each having a horizontal dimension of 500 mm, a vertical dimension of 600 mm, and a thickness of 1.8 mm were prepared for the glass plates forming the through holes. And the through-hole used as an exhaust hole was formed in the said glass plate. In either case, the preceding drill was entered from the lower side of the glass substrate, and the subsequent drill was entered from the upper side of the glass substrate for drilling.

Here, the drill which concerns on an Example used the drill (core drill) of the shape shown in FIG. The outer diameter was 2.0 mm. As for the dimensions of the other parts, and _{d 1 = 0.54mm, L 1 =} 1.04mm, and L ₂ = 1.1 mm (see Figure 1). On the other hand, the drill according to the conventional example used a core drill having a constant outer diameter as shown in FIG. The outer diameter was 2.0 mm as in the example.

Then, the glass plate having the through holes formed as described above is damaged by applying thermal bending to the glass plate, and the Weibull plot processing is performed on the heat intensity data obtained by the fracture surface analysis of the broken fracture surface. The thermal strength at a failure probability of 10% was calculated for each example and comparative example. Here, the thermal bending was performed by a rubber heater method in which a rubber heater was attached to each glass plate and one end surface of the glass plate was heated. The results are shown in Table 1 below.

  The above-mentioned damage due to thermal bending usually occurs from the rough surface or chipping (including fine cracks) of the processed surface (through hole) or its periphery, so the higher the thermal strength, the rougher the processed surface or its periphery. It means that there are many roughness and cracks in a processed surface or its periphery, so that there are few and fragile and heat intensity is low. Here, according to Table 1 above, the glass plate (Example) in which the through hole is formed with the drill according to the present invention has a thermal strength higher than the glass plate (Comparative Example) in which the through hole is formed with the conventional drill. Since it is high, it turns out that the production apparatus of the glass plate provided with the drill which concerns on this invention is effective for generation | occurrence | production suppression of a crack.

DESCRIPTION OF SYMBOLS 1 Leading drill 2 Subsequent drill 3 Glass plate 11 trunk | drum 12 small diameter part 13 splice part 14 enlarged diameter part 21 trunk | drum 22 small diameter part 23 splice part 24 enlarged diameter part 31 bottomed hole 32 core 33 opening part (preceding drill intrusion side) )
34 Through-hole 35 Opening (rear drill entry side)

Claims (7)

After cutting from one end surface side of the glass plate to penetrate the leading drill in the thickness direction to form a bottomed hole, the preceding drill is retracted, and thereafter, cutting from the other end surface side of the glass plate is performed. In a glass plate manufacturing apparatus configured to form a through hole in the glass plate by allowing a subsequent drill to penetrate coaxially with the preceding drill,
At least one of the drills includes a barrel portion having a constant outer diameter along the axial direction, a small-diameter portion that is located on a drill base end side of the barrel portion and has a smaller outer diameter than the barrel portion, and the barrel A cutting portion is provided to a portion from the tip of the one drill to at least the body side of the connecting portion, and a connecting portion connecting the portion and the small diameter portion, and
An apparatus for producing a glass plate, characterized in that at least a part of the connecting portion reaches the inside in the thickness direction of the glass plate in a state where the one drill is inserted deepest.   The said connection part is a manufacturing apparatus of the glass plate of Claim 1 which has a shape gradually diameter-reduced as it goes to the drill base end side from the said trunk | drum.   The said connection part is a manufacturing apparatus of the glass plate of Claim 1 or 2 which has a shape which reduces in diameter in a taper shape.   The said one drill is a manufacturing apparatus of the glass plate in any one of Claims 1-3 integrally provided with the enlarged diameter part which is located in the drill front end side of the said trunk | drum, and expands gradually as it goes to the said trunk | drum.   The said one drill is the said precedent drill, Comprising: The axial direction dimension from the front-end | tip to the edge part by the side of the said connection part of the said trunk | drum is smaller than the thickness dimension of the said glass plate. Glass plate manufacturing equipment.   The one drill is a core drill, and abrasive grains for cutting are fixed to the surface of the body part and the joint part, and the difference between the outer diameter of the body part and the outer diameter minimum value of the joint part Is set to at least twice the average particle size of the cutting abrasive grains. After cutting from one end surface side of the glass plate to penetrate the leading drill in the thickness direction to form a bottomed hole, the preceding drill is retracted, and thereafter, cutting from the other end surface side of the glass plate is performed. In the method of manufacturing a glass plate, including a drilling step of forming a through hole in the glass plate by allowing a subsequent drill to penetrate coaxially with the preceding drill,
At least one of the drills has a barrel portion having a constant outer diameter along the axial direction, a small-diameter portion located on the drill base end side of the barrel portion and having a smaller outer diameter than the barrel portion, and the barrel A connecting portion that connects the portion and the small diameter portion, and a portion having cutting ability at least from the tip of the one drill to the body portion side of the connecting portion is used in the drilling step, and ,
In the state which penetrated said one drill to the deepest, the said connection part reached | attained to the thickness direction inner side of the said glass plate, The manufacturing method of the glass plate characterized by the above-mentioned.

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