JP5001705B2 - Hard and brittle plate - Google Patents

Description

  The present invention relates to a hard and brittle material plate provided with a through hole formed so as to penetrate through the front and back surfaces.

  A hard and brittle material plate provided with a conventional through hole has a through hole formed by rotating a grindstone portion in which a grindstone made of diamond or the like is attached to the tip of a steel shank (see, for example, Patent Document 1). ).

Japanese Patent Laying-Open No. 2005-199619 (page 6, FIG. 12)

  However, in Patent Document 1, since the inner peripheral surface of the through hole formed in the hard and brittle material plate is formed linearly in the through direction of the through hole, the hard and brittle material in which the through hole is formed. During handling such as moving the plate, loads such as bending loads concentrate on this step on the inner peripheral surface of the through hole, and the hard and brittle material plate is likely to break, making it difficult to handle the hard and brittle material plate. It was.

  For example, when a hard and brittle material plate having a through hole is gripped by gripping means having a moving function and the plate surface is arranged substantially parallel to the floor surface, the entire hard and brittle material plate is bent by its own weight. A load will be generated. The stress due to the bending load is likely to act in a through-hole penetrating the front and rear surfaces of the plate surface at a predetermined position of the hard and brittle material plate spreading in the plane direction. For example, in a state where the hard and brittle material plate is gripped by the gripping means. When attempting to move, even a slight impact may cause a crack in the inner peripheral surface of the through hole, resulting in damage to the hard and brittle material plate.

  The present invention has been made paying attention to such problems, and an object of the present invention is to provide a hard and brittle material plate having a through-hole that is not easily damaged by handling such as gripping and moving.

In order to solve the above problems, the hard and brittle material plate according to claim 1 of the present invention is
A hard and brittle material plate having a through hole whose inner peripheral surface is ground using a drill,
The inner peripheral surface of the through-hole rotates the drill around the axis of the drill and gives a relative eccentric motion between the drill and the hard and brittle material plate. a curved portion which is formed only from a curved surface increases in continuous from the surface of the tangent slope angle hard and brittle materials plate toward the back side with respect to the reference plane parallel virtual, curved surface portion is hard and brittle materials plate It is characterized by being formed in a diameter larger than the opening portions of the through holes formed on both the front and back surfaces.
According to this feature, since the inner peripheral surface of the through hole is a curved surface portion in which the inclination of the tangent continues along the penetrating direction, the inner peripheral area of the through hole compared to the linear inner peripheral surface along the penetrating direction. In the through hole where the bending load applied to the hard and brittle material plate is likely to concentrate, the stress acting on the inner peripheral surface of the through hole can be kept small, and the curved surface has no corners, Since the stress due to the bending load is dispersed without being locally applied, the hard and brittle material plate is difficult to break against the bending load.
In addition, the curved portion of the through hole is formed to have a larger diameter than the opening of the through hole formed on both the front and back surfaces of the hard and brittle material plate, so that the bending load applied to the hard and brittle material plate has the largest effect. It is possible to improve the cracking resistance against bending load on the front and back surfaces of the hard and brittle material plate. In addition, since the stress due to the bending load applied to the hard and brittle material plate is dispersed in the direction away from the through hole in the radial direction, the bending load concentrated on the through hole is subjected to the radial peripheral portion of the through hole in the hard and brittle material plate. You can take care of it.

The hard and brittle material plate according to claim 2 of the present invention is the hard and brittle material plate according to claim 1 ,
The curved surface portion is characterized in that it is formed substantially symmetrically in the penetrating direction with a central plane located in the middle between the front and back surfaces of the hard and brittle material plate.
According to this feature, the virtual center surface where both the tensile force and the compressive force acting on the hard and brittle material plate are substantially 0 can be positioned between the front and back surfaces of the hard and brittle material plate. The difficulty of cracking the hard and brittle material plate against bending load can be improved.

The hard and brittle material plate according to claim 3 of the present invention is the hard and brittle material plate according to claim 2 ,
The curved surface portion has only a uniform curvature along the penetrating direction.
According to this feature, a curved surface portion having only a uniform curvature along the penetrating direction is formed on the inner peripheral surface of the through hole, and the tangential slope is continuously uniform on the inner peripheral surface of the through hole. Therefore, the stress due to the bending load can be evenly dispersed.

The hard and brittle material plate according to claim 4 of the present invention is the hard and brittle material plate according to any one of claims 1 to 3 ,
A chamfered portion is formed in the opening portion of the through-hole so as to continue the curved surface portion and at least one of the front and back surfaces of the hard and brittle material plate.
According to this feature, a chamfered portion that is continuous with at least one of the curved surface portion and the front and back surfaces of the hard and brittle material plate is formed in the opening of the through hole. Not likely to occur.

  Examples of the present invention will be described below.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic perspective view showing an application example of a hard and brittle material plate according to the present invention. FIG. 2 is a perspective view showing the hole forming drill in Example 1 of the present invention. FIG. 3 is a front view similar to FIG. FIG. 4 is a side view similar to FIG. FIG. 5 is a cross-sectional side view similar to FIG. FIG. 6 is a cross-sectional view showing a situation where a plate glass is perforated as in FIG. FIG. 7 is a cross-sectional view taken along the line AA of FIG. FIG. 8A is a cross-sectional view showing a situation where the plate glass is penetrated similarly to FIG. 2, and FIG. 8B is a cross-sectional view showing a situation where grinding is performed by the intermediate grindstone portion. FIG. 9A is a cross-sectional view showing a ground hole of a plate glass after grinding, as in FIG. 2, and FIG. 9B is a cross-sectional view showing a state in which a bending load is applied to the plate glass. FIG. 13A is a diagram illustrating an inclination angle of a tangent at a position in the grinding hole penetration direction in Example 1, and FIG. 13B is a graph showing an inclination angle of the tangent at a position in the penetration direction of the grinding hole. It is.

  First, as shown in FIG. 1, an application example of a hard and brittle material plate provided with through holes penetrating the front and back surfaces will be described. The plasma display panel 1 includes a front case portion 2 and a back case portion 8 which are combined with each other to form a case, and an internal unit 10 accommodated in the case.

  The internal unit 10 includes a chassis member 7 as a heat dissipation holding plate, a display panel 9 supported on the front surface of the chassis member 7, and heat as an adhesive member interposed between the chassis member 7 and the display panel 9. The conductive sheet 6 and the optical function filter 3 having functions such as antistatic, color tone / brightness correction, electromagnetic wave shielding, etc., are disposed on the front surface of the display panel 9.

  The display panel 9 is composed of a plate glass 4 provided on the front side and a plate glass 5 as a hard and brittle material plate provided on the back side. The plate glass 4 has a long side direction longer than the plate glass 5 and a short side. The direction is short. Accordingly, there is a region where the plate glass 4 and the plate glass 5 do not overlap each other, and terminals (not shown) connected to electrodes (not shown) provided in the display panel 9 are formed in the non-polymerized region. . A plurality of film-like wiring (not shown) having a connector (not shown) at the tip is crimped to this terminal, and the connector is provided on a circuit board (not shown) arranged on the back surface of the chassis member 7. By being coupled to (not shown), the circuit board and the display panel 9 are electrically connected.

  The peripheral portions of the front side glass plate 4 and the rear side glass plate 5 are bonded and sealed with a sealing material (not shown) made of low melting point glass to form a gas discharge space, and the gas discharge is sealed. A rare gas (such as a mixed gas of neon and xenon) having a predetermined pressure is sealed in the space.

  And the through-hole for distribute | circulating the noble gas enclosed in the inside of the above-mentioned gas discharge space is formed in the predetermined location near the corner | angular part of the plate glass 5 so that the front and back of the plate glass 5 may be penetrated. Below, the formation process of the through-hole by the drill for hole formation is demonstrated.

  Reference numeral 11 in FIG. 2 is a diamond drill as a hole forming drill in the present embodiment. The diamond drill 11 includes a diamond grindstone portion 12 as a grindstone portion in which diamond is mounted on a front end surface and an outer peripheral surface, and a rotating shaft. It is comprised with the steel shank 13 which acts as. The diamond grindstone portion 12 is manufactured as a metal bond grindstone or an electrodeposition grindstone using diamond abrasive grains.

  Further, as shown in FIGS. 2 to 4, the diamond grindstone portion 12 includes a tip grindstone portion 14 as a small-diameter penetrating grindstone portion formed on the tip side and an intermediate portion formed from the tip grindstone portion 14. And a rear grinding wheel portion 15 as a curved grinding portion having a large diameter.

  Coarse diamond abrasive grains having a large particle size are attached to the tip grindstone portion 14, and fine diamond abrasive grains having a particle size smaller than that of the diamond abrasive grains adhered to the tip grindstone portion 14 are attached to the rear grindstone portion 15. It is attached.

  Further, the tip grindstone portion 14 has a substantially cylindrical shape formed with substantially the same diameter along the axial direction, and a cylindrical surface 14 a is formed on the side periphery of the tip grindstone portion 14. On the distal end side, a conical surface 14b is formed so that the diameter decreases toward the distal end. As shown in the partial enlarged perspective view of FIG. 2, the tip of the tip grindstone 14 has a tip surface 14c formed by flattening the tip of the cone formed by the cone surface 14b. In other words, the shape of the tip portion of the tip grindstone portion 14 is a truncated cone shape.

  The rear grindstone 15 is provided on the rear side in the axial direction of the diamond drill 11 with respect to the tip grindstone 14, and has a curved surface that bulges in the radial direction of the rotating shaft. More specifically, the rear grindstone 15 is a curved surface in which the tangential inclination continues along the axial direction of the rotation axis, and an opening grinding surface 15a for grinding the opening on the surface of the hard and brittle material plate; Similarly, an opening grinding surface 15c that grinds the opening on the back surface of the hard and brittle material plate, and the diameter of the opening grinding surface 15a and 15c is gradually increased from that of the hard and brittle material plate. It has a curved surface comprising an inner grinding surface 15b to be ground. Further, the rear grindstone portion 15 includes a continuous curved surface that is substantially symmetrical in the axial direction with a central portion located in the middle of the inner grinding surface 15b in the axial direction of the rotating shaft.

  At the center portion of the tip surface 14c of the tip grindstone portion 14 is formed a minute recess 14d that is formed in a substantially hemispherical shape. Further, as shown in FIG. 3, the tip surface 14c of the tip grindstone portion 14 has a substantially circular shape when viewed from the front of the diamond drill 11, and the recess 14d formed on the tip surface 14c is a concentric circle of the tip surface 14c. Is formed.

  Next, the process of grinding the plate glass 5 as a hard and brittle material plate using the diamond drill 11 will be described in detail with reference to FIGS. As shown in FIG. 5, when grinding the plate glass 5, which is a hard and brittle material plate, using the diamond drill 11, first the diamond drill 11 is rotated about the axis α of the shank 13, and the tip grindstone portion 14 is brought into contact with the surface of the plate glass 5. At this time, since the tip of the tip grindstone portion 14 has a truncated cone shape, the pressing force is concentrated on the tip surface 14c, and the plate glass 5 is easily ground.

  Further, as shown in FIG. 6, the diamond wheel 12 of the diamond drill 11 rotates about the axis α of the shank 13, and a relative eccentric motion occurs between the diamond wheel 12 and the plate glass 5. It has come to be given.

  The eccentric motion of the diamond drill 11 will be described in detail. As shown in FIG. 7, the cylindrical surface 14 a of the tip grindstone portion 14 of the diamond drill 11 has a substantially circular grinding hole 17 that is a surface to be ground formed on the plate glass 5. The cylindrical surface 14a of the tip grindstone 14 abuts over the entire circumference of the inner peripheral surface of the grinding hole 17 while rotating the diamond drill 11 about the axis α in the direction a. As described above, the axis α of the shaft rotation of the diamond drill 11 is rotated in the b direction around the eccentric shaft β, that is, the diamond drill 11 is rotated on the planetary axis about the eccentric shaft β. The eccentric shaft β is the central axis of the circular grinding hole 17.

  As a means for giving a relative eccentric motion between the diamond drill 11 and the plate glass 5, a first motor (not shown) that fixes the plate glass 5 in a stationary state and rotates the diamond drill 11 about the axis α. ) And a second motor (not shown) for rotating the diamond drill 11 and the first motor around an eccentric shaft β that is the central axis of the grinding hole 17. There is a method of giving a relative eccentric motion between the diamond drill 11 and the plate glass 5 by driving both.

  Further, by giving an eccentric motion to the diamond drill 11, the diameter of the grinding hole 17 formed in the plate glass 5 is larger than the outer diameter of the tip grindstone portion 14, and as will be described later, the outer diameter of the rear grindstone portion 15. It is formed to be larger. The diameter of the grinding hole 17 changes depending on the separation distance e between the axis α of the rotation axis of the diamond drill 11 and the eccentric shaft β of the eccentric motion, and the separation between the axis α and the eccentric shaft β. If the distance e is large, the diameter of the grinding hole 17 is formed large.

  Furthermore, in the diamond drill 11 in the present embodiment, the diamond grindstone 12 is rotated about the axis α of the shank 13, and the tip surface 14c passes through at least the center point (eccentric axis β) of the grinding hole 17. Further, the plate glass 5 is ground by giving an eccentric motion between the diamond grindstone portion 12 and the plate glass 5. Therefore, when the diamond grindstone 12 is axially rotated, the tip of the diamond grindstone 12 that is eccentrically moved at the position corresponding to the recess 14d and the remaining portion of the plate glass 5 generated at the center point of the grinding hole 17 (eccentric axis β). The surface 14c can be ground away.

  Moreover, the recessed part 14d can accommodate temporarily the chip generate | occur | produced when the plate glass 5 is ground. Therefore, it is possible to prevent a reduction in the grinding efficiency of the diamond drill 11 caused by the chips being interposed between the tip surface 14 c of the diamond grindstone 12 and the plate glass 5. In the grinding using the diamond drill 11, cleaning water can be poured into the gap between the grinding hole 17 and the tip grindstone portion 14, so that chips and the like generated by grinding can be ground while washing with this cleaning water. It has become.

  Further, the concave portion 14d has a shape that becomes narrower as it goes to the inner portion thereof. By doing so, chips and the like generated during grinding of the glass sheet 5 can be easily removed from the concave portion 14d. Since powder or the like is less likely to be clogged in the recess 14d, the diamond drill 11 can be easily maintained after use.

  After the tip grindstone portion 14 penetrates the plate glass 5, the cylindrical surface 14a of the tip grindstone portion 14 is gradually increased by increasing the separation distance e between the shaft rotation axis α of the diamond drill 11 and the eccentric shaft β of the eccentric motion. By grinding the inner peripheral surface of the grinding hole 17, the grinding hole 17 is enlarged so that the diameter of the grinding hole 17 is increased.

  8A, the diameter L2 of the grinding hole 17 is formed to be larger than the outer diameter L1 of the inner grinding surface 15b of the rear grinding wheel portion 15 by the above-described eccentric motion by the tip grinding wheel portion 14. After that, the diamond grindstone 12 is further inserted into the grinding hole 17 in the axial direction, and the rear grindstone 15 is brought into contact with the inner peripheral surface of the grinding hole 17. Then, as shown in FIG. 8B, while rotating the diamond drill 11 around the axis α, the peripheral surface of the rear grindstone 15 extends over the entire inner peripheral surface of the grinding hole 17. The diamond drill 11 is moved eccentrically.

  Further, after forming the grinding hole 17 penetrating the plate glass 5 by the tip grindstone portion 14 in this way, the relative position between the diamond grindstone portion 12 and the plate glass 5 is moved in the axial direction of the diamond drill 11, and the tip grindstone portion 14 is moved. By providing an eccentric motion between the rear glass wheel 15 that is a curved surface that bulges in the radial direction of the rotating shaft formed on the rear side, and the glass sheet 5, the glass sheet 5 is provided along the rear wheel part 15. A grinding hole 17 having a curved surface with a different shape can be formed. That is, as shown in FIG. 9A, the inner peripheral surface of the grinding hole 17 as a through hole is tangent along the penetration direction along the curved surface bulging outward in the radial direction of the rear grinding wheel portion 15. Is a curved surface portion whose diameter is continuously expanded radially outward. Specifically, the curved surface portion is formed to have a diameter L2 in the opening portion of the front surface 5a and the back surface 5b of the plate glass 5, and gradually increases in diameter toward the intermediate surface 5c, and from the diameter L2 in the intermediate surface 5c. Is also formed to have a large diameter L3. In addition, the curved surface portion is formed substantially symmetrically in the penetrating direction with the center surface 5c located in the middle between the front surface 5a and the back surface 5b of the plate glass 5 as a center. In addition, since the back grindstone part 15 is formed in a larger diameter than the front-end grindstone part 14, the diamond drill 11 of a present Example is suitable for the use which forms the comparatively large diameter grinding hole 17. FIG.

  In addition, since diamond abrasive grains finer than diamond abrasive grains attached to the tip grindstone portion 14 are adhered to the rear grindstone portion 15, the rear grindstone portion 15 can chamfer the inner peripheral surface of the grinding hole 17. It has become. It is also possible to provide a conical surface in the diamond grindstone 12 and chamfer the periphery of the grinding hole 17 using the conical surface.

  In this way, after forming the grinding hole 17 by penetrating the plate glass 5 using the tip grinding wheel portion 14 to which coarse diamond abrasive grains are first attached, the grinding hole is formed by the rear grinding stone portion 15 to which fine diamond abrasive grains are adhered. By chamfering 17, not only the grinding time for forming the grinding hole 17 in the plate glass 5 can be shortened, but also the replacement work between the drill for penetration and other chamfering tools is not required, and the grinding hole 17 is formed. The work time can be shortened.

  Next, as shown in FIG. 13A, the inclination of the tangent of the curved surface portion in the grinding hole 17 formed in the glass sheet 5 of the present embodiment will be described. A virtual reference plane parallel to the surface 5a of the glass sheet 5 The inclination angle θ of the tangent to K continuously changes as θ1 to θ6 illustrated in FIG. As shown in FIG. 13B, the inclination angle θ (vertical axis) of the tangential line at the position t (horizontal axis) in the penetration direction of the grinding hole 17 formed in the plate glass 5 is the surface 5a (t = 0) continuously increases toward the back surface 5b (t = T). Specifically, in the virtual intermediate surface 5c (t = T / 2) between the front surface 5a and the back surface 5b of the plate glass 5, the inclination angle θ4 indicates π / 2, and the surface of the plate glass 5 is centered on the intermediate surface 5c. The inclination angle θ changes substantially symmetrically toward the back surface.

  Next, as shown in FIG. 9B, the bending load acting on the plate glass 5 having the grinding holes 17 formed by the diamond drill 11 as described above will be described. For example, the surface 5a of the plate glass 5 is used as the upper surface. When gripped by a gripping means (not shown), a bending load is applied in the direction of the outlined arrow. Specifically, a tensile force is generated on the surface 5a side around the intermediate surface 5c of the plate glass 5, and this tensile force acts as the largest force on the surface 5a. Similarly, a compressive force is generated on the back surface 5b side of the intermediate surface 5c, and this compressive force acts as the largest force on the back surface 5b.

  Next, the bending load acting on the inner peripheral surface of the grinding hole 17 penetrating the front and back surfaces of the plate glass 5 will be described. The stress due to the bending load acts toward the tangential direction in the penetrating direction of the inner peripheral surface of the grinding hole 17. To do. As described above, a curved portion having a continuous tangential slope along the penetration direction is formed on the inner peripheral surface of the grinding hole 17 by the rear grinding wheel portion 15 formed on the diamond grinding wheel portion 12 of the diamond drill 11. Therefore, the inner peripheral area of the grinding hole 17 is larger than the linear inner peripheral surface along the penetrating direction, and the grinding hole 17 on which the bending load applied to the plate glass 5 tends to concentrate acts on the inner peripheral surface of the grinding hole 17. Not only can the stress be kept small, but there is no corner portion in the curved surface portion, and the stress due to the bending load is dispersed without being locally applied, so that the plate glass 5 is difficult to break against the bending load.

  In particular, as in this embodiment, the rear grindstone portion 15 of the diamond drill 11 is located on the inner side of the opening portion of the plate glass 5 from the opening grinding surfaces 15a and 15c for grinding the openings on the front surface 5a and the back surface 5b of the plate glass 5. As shown in FIG. 9 (a), openings that are ground by the opening grinding surfaces 15a and 15c have a curved surface that gradually increases in diameter toward the inner grinding surface 15b that grinds the side. Since the hole diameter L2 of the part can be formed smaller than the hole diameter L3 ground by the inner part grinding surface 15b, that is, on the inner peripheral surface of the grinding hole 17, from the opening part toward the inner part in the penetration direction, Since the curved surface portion in which the hole diameter gradually increases is formed, it is possible to improve the cracking resistance against the bending load on the front surface 5a or the back surface 5b of the glass plate 5 where the bending load applied to the glass plate 5 acts most greatly. That. Further, since the stress due to the bending load applied to the plate glass 5 is dispersed in the direction away from the grinding hole 17 in the radial direction, the bending load concentrated on the grinding hole 17 is applied to the peripheral portion in the radial direction of the grinding hole 17 in the plate glass 5. Can be held.

  Further, since the rear grinding wheel portion 15 having a continuous curved surface that is substantially symmetrical in the axial direction around the center portion of the inner grinding surface 15b, a curved surface along the rear grinding wheel portion 15 can be formed on the plate glass 5, Since the imaginary center plane where both the tensile force and the compressive force acting on the plate glass 5 are substantially zero can be positioned in the middle of the front and back surfaces of the plate glass 5, it is difficult to break the plate glass 5 against bending load. Can be improved. Further, a bending load in a direction in which a tensile force is applied to the surface 5a of the plate glass 5 and a compression force is applied to the back surface 5b, which occurs when the surface 5a of the plate glass 5 is held upward, The same difficulty of cracking can be generated against a bending load in which a tensile force is applied to the back surface 5b of the plate glass 5 and a tensile force is applied to the surface 5a, which occurs when the back surface 5b is gripped upward.

  Furthermore, a curved surface portion having only a uniform curvature along the penetrating direction is formed on the inner peripheral surface of the grinding hole 17, and the inclination of the tangent line is continuously uniform on the inner peripheral surface of the grinding hole 17, Stress due to bending load can be evenly dispersed.

  Next, a hard and brittle material plate having a through hole according to Example 2 will be described with reference to FIG. FIG. 10 is a cross-sectional view showing a plate glass grinding hole in Example 2 of the present invention. In addition, the same structure as the said Example is abbreviate | omitted.

  As shown in FIG. 10, the inner peripheral surface of the grinding hole 27 as a through hole formed in the plate glass 5 is formed to have a larger diameter than the opening of the grinding hole 27 formed on the front and back surfaces of the plate glass 5. In addition to the curved surface portion 27c, the curved surface portion 27c and the front surface 5a of the plate glass 5 have a chamfered portion 27a, and the curved surface portion 27c and the back surface 5b of the plate glass 5 have a chamfered portion 27b. Not only can the stress due to the bending load be released in the tangential direction of the chamfered portions 27a and 27b, but chamfering makes it difficult to cause defects when the plate glass 5 is handled. Further, the grinding hole 27 is formed substantially symmetrically in the penetrating direction with the center surface 5c located in the middle between the front surface 5a and the back surface 5b of the plate glass 5 as a center. The chamfered portion is not necessarily formed on both the front surface 5a and the back surface 5b of the plate glass 5, and may be formed only on either the front surface 5a or the back surface 5b of the plate glass 5.

  Next, a hard and brittle material plate having a through hole according to Example 3 will be described with reference to FIGS. 11 and 14. FIG. 11: is sectional drawing which shows the grinding hole of the plate glass in Example 3 of this invention. FIG. 14 is a graph showing the inclination angle of the tangent line at the position in the penetration direction of the grinding hole in Example 3. In addition, the same structure as the said Example is abbreviate | omitted.

  As shown in FIG. 11, the inner peripheral surface of the grinding hole 57 as a through-hole formed in the plate glass 5 penetrates from the surface 5a side of the plate glass 5 to the middle between the front surface 5a and the back surface 5b. An inner peripheral surface 57a that extends linearly in the direction, a curved surface portion 57b that is continuous with the inner peripheral surface 57a and gradually reduces in diameter in the penetrating direction, and a reduced diameter portion 57b ′ that is the most reduced diameter of the curved surface portion 57b. And an inner peripheral surface 57c extending linearly in the penetrating direction to the back surface 5b of the plate glass 5.

  As shown in FIG. 14, the inclination of the tangential line of the grinding hole 57 formed in the glass sheet 5 of the present embodiment will be described. The inclination angle θ of the tangential line is the surface 5a of the glass sheet 5 formed by the inner peripheral surface 57a ( From t = 0) toward the intermediate surface 5c (t = T / 2), it is constant π / 2, and the inclination angle θ is the back surface 5b (t = T) of the plate glass 5 on which the inner peripheral surface 57b is formed. It increases continuously toward the side. Further, the inclination angle θ of the tangent line changes discontinuously at the reduced diameter portion 57b ′ (t = T1), and is constant π / 2 from the portion to be ground (t = T1) to the back surface 5b (t = T). is there.

  Next, a hard and brittle material plate having a through hole according to Example 4 will be described with reference to FIGS. FIG. 12 is a cross-sectional view showing a plate glass grinding hole in Example 4 of the present invention. FIG. 15A is a diagram illustrating the inclination angle of the tangent at the position in the grinding hole penetration direction in Example 4, and FIG. 15B is a graph showing the inclination angle of the tangent at the position in the penetration direction of the grinding hole. It is. In addition, the same structure as the said Example is abbreviate | omitted.

  As shown in FIG. 12, the curved surface portion formed on the inner peripheral surface of the grinding hole 67 as a through-hole formed in the plate glass 5 is a grinding hole 67 formed on both the front surface 5 a and the back surface 5 b of the plate glass 5. In other words, the hole diameter is gradually reduced from the opening toward the inner part in the penetration direction, and the intermediate between both the front surface 5a and the back surface 5b of the plate glass 5 is formed. It is formed substantially symmetrically in the penetrating direction with the center plane 5c located at the center. By doing so, the curved surface portion can be used as a chamfered surface continuous with the front surface 5a or the back surface 5b of the plate glass 5, and a virtual force in which both the tensile force and the compressive force acting on the plate glass 5 become substantially zero. Since the center surface of can be positioned in the middle of the front and back surfaces of the plate glass 5, it is possible to improve the difficulty of breaking the plate glass 5 against bending load. Moreover, the same cracking difficulty may be produced with respect to the bending load in the direction in which the tensile force is applied to the front surface 5a of the plate glass 5 and the bending load in which the tensile force is applied to the back surface 5b of the plate glass 5 in the opposite direction. it can.

  Next, as shown in FIG. 15A, the inclination of the tangent of the curved surface portion in the grinding hole 67 as the through hole formed in the plate glass 5 of this embodiment will be described. The inclination is parallel to the surface 5 a of the plate glass 5. The inclination angle θ of the tangent to the virtual reference plane K changes continuously as θ1 to θ6 exemplified in FIG. As shown in FIG. 15 (b), the inclination angle θ (vertical axis) of the tangent line at the position t (horizontal axis) in the penetrating direction of the grinding hole 67 formed in the plate glass 5 is the surface 5a (t = 0) continuously decreases from the back surface 5b (t = T). Specifically, in the virtual intermediate surface 5c (t = T / 2) between the front surface 5a and the back surface 5b of the plate glass 5, the inclination angle θ4 indicates π / 2, and the surface of the plate glass 5 is centered on the intermediate surface 5c. The inclination angle θ changes substantially symmetrically toward the back surface.

  Further, a curved surface portion having only a uniform curvature along the penetrating direction is formed on the inner peripheral surface of the grinding hole 67, and the inclination of the tangent line is continuously uniform on the inner peripheral surface of the grinding hole 67. Stress due to bending load can be evenly dispersed.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments, and modifications and additions within the scope of the present invention are included in the present invention. It is.

  For example, in the above-described embodiment, a through-hole in which a curved surface portion in which the tangential slope is continuous along the penetration direction is formed on the inner peripheral surface is shown. 13 (a) and (b) in FIG. 15 or FIGS. 15 (a) and 15 (b) in Example 4, even if it changes continuously over the penetration direction of the hard and brittle material plate Alternatively, as shown in FIGS. 11 and 14 in the third embodiment, only a portion along the penetration direction of the hard and brittle material plate may have a continuously changing portion. In addition, the cross-sectional view shape of the inner peripheral surface of the through hole is not necessarily limited to the present embodiment, and may be, for example, a substantially sinusoidal cross-sectional view, or the curved surface shape is a substantially quadratic curve in cross-sectional view, for example. Then, as shown in FIG. 16, the tangent slope may increase or decrease linearly, that is, the tangent slope may be expressed by a linear expression. That is, the curved surface portion where the tangent gradient is continuous is a surface excluding a surface where the tangent gradient is constant. Here, for example, as shown in FIG. 17A, the surface where the inclination of the tangent is constant is such that the inner peripheral surface of the grinding hole 87 as a through hole of the plate glass 5 is orthogonal to the front and back surfaces of the plate glass 5. An inner peripheral surface 87b formed in the direction, a chamfered portion 87a formed on the plate glass surface 5a side of the inner peripheral surface 87b, and a chamfered portion 87c formed on the plate glass back surface 5b side of the inner peripheral surface 87b. As shown in FIG. 17B, the tangential inclination angle θ (vertical axis) is relative to the position t (horizontal axis) in the penetrating direction of the grinding hole 87, as shown in FIG. Shown in parallel.

  Moreover, in the said Example, the plate glass 5 in the plasma display panel 1 is shown as an application example of the hard-brittle material board provided with the through-hole, and the grinding hole for distribute | circulating the noble gas enclosed inside as the said through-hole is shown. However, for example, the material of the hard and brittle material plate may be a resin material or the like, and for example, the use of the through hole provided in the hard and brittle material plate is an insertion hole or the like for inserting a screw member. Also good.

It is a schematic perspective view which shows the example of application of the hard-brittle material board which concerns on this invention. It is a perspective view which shows the drill for hole formation in Example 1 of this invention. FIG. 3 is a front view similar to FIG. 2. FIG. 3 is a side view similar to FIG. 2. FIG. 3 is a sectional side view similar to FIG. 2. It is sectional drawing which shows the condition which perforates plate glass similarly to FIG. It is AA sectional drawing of FIG. (A) is sectional drawing which shows the condition which penetrated the plate glass similarly to FIG. 2, (b) is sectional drawing which shows the condition ground with an intermediate grindstone part. (A) is sectional drawing which shows the grinding hole of the plate glass after grinding similarly to FIG. 2, (b) is sectional drawing which shows the condition where the bending load was applied to plate glass. It is sectional drawing which shows the grinding hole of the plate glass in Example 2 of this invention. It is sectional drawing which shows the grinding hole of the plate glass in Example 3 of this invention. It is sectional drawing which shows the grinding hole of the plate glass in Example 4 of this invention. (A) is the figure which illustrated the inclination angle of the tangent in the position of the penetration direction of a grinding hole in Example 1, (b) is a graph which shows the inclination angle of the tangent in the position of the penetration direction of a grinding hole. . It is a graph which shows the inclination angle of the tangent in the position of the penetration direction of a grinding hole in Example 3. FIG. (A) is the figure which illustrated the inclination angle of the tangent in the position of the penetration direction of a grinding hole in Example 4, (b) is a graph which shows the inclination angle of the tangent in the position of the penetration direction of a grinding hole. . It is a graph which shows the inclination angle of the tangent in the position of the penetration direction of the grinding hole formed in a cross sectional view substantially quadratic curve. (A) is sectional drawing which shows the grinding hole formed in the linear form which cross-sectional view of plate glass continued. (B) is a graph which shows the inclination angle of the tangent in the position of the penetration direction of a grinding hole.

Explanation of symbols

1 Plasma display panel 5 Flat glass (hard brittle material plate)
5a Front surface 5b Back surface 5c Intermediate surface 11 Diamond drill 12 Diamond grindstone portion 13 Shank 14 Tip grindstone portion 15 Rear grindstone portion 17 Grinding hole (through hole)
27 Grinding hole (through hole)
27a Chamfered portion 27b Chamfered portion 27c Curved surface portion 57 Grinding hole (through hole)
57a Inner peripheral surface 57b Curved surface portion 57b 'Reduced diameter portion 57c Inner peripheral surface 67 Grinding hole (through hole)
87 Grinding hole 87a Chamfer 87b Inner peripheral surface 87c Chamfer

Claims (4)

A hard and brittle material plate having a through hole whose inner peripheral surface is ground using a drill,
The inner peripheral surface of the through-hole rotates the drill around the axis of the drill and gives a relative eccentric motion between the drill and the hard and brittle material plate. a curved portion which is formed only from a curved surface increases in continuous from the surface of the tangent slope angle hard and brittle materials plate toward the back side with respect to the reference plane parallel virtual, curved surface portion is hard and brittle materials plate A hard and brittle material plate, characterized in that it is formed to have a diameter larger than the opening portions of the through holes formed on both the front and back surfaces.   2. The hard and brittle material plate according to claim 1, wherein the curved portion is formed substantially symmetrically in a penetrating direction around a center plane located between the front and back surfaces of the hard and brittle material plate.   The hard and brittle material plate according to claim 2, wherein the curved portion has only a uniform curvature along the penetrating direction.   The chamfered part which continues the at least any one surface of the said curved surface part and the hard-brittle material board in the opening part of the said through-hole is formed in any one of Claim 1 thru | or 3 characterized by the above-mentioned. Hard and brittle material plate.

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