JPH09225802A - Polishing method and device for glass panel for cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure polishing with less distorsion or uneveness in a device to perform polishing a glass pannel placed onto a table with a disc-like polishing unit while pressing it thereto by reciprocally moving the unit in a circular form around a point on arbitral straight line almost perpendicular to a rotation shaft of the unit. SOLUTION: A glass pannel 2 is placed onto a rotation table 3 and the table 3 is rotated at a specified rotation frequency by a motor 10. Above the table 3 a recessed disc-like polishing unit 1 is disposed and the unit 1 is pressed against a face of a pannel 2 while being rotated with a roation axis being a straight line perpendicular to the center of disc. The unit 1 is fixed to a rotation shaft 4 to which motive power of the motor 5 is transmitted, and the frame 6 is arranged on a rotation shaft 8 on a base structure 7 of polishing device. The support frame 6 is adapted to move reciprocally in a circular form to the structure 7 with the rotation shaft 8 being the center of rotation and is composed of electric motor 9 and an eccentric plate 11.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polishing method and a polishing apparatus for a glass panel for a cathode ray tube.

[0002]

2. Description of the Related Art Conventionally, a glass panel constituting an image display portion of a cathode ray tube of a television or a display is
A glass gob that has been melted at around 000 ° C. is filled in a mold and pressed to form the glass. However, in the manufacturing method using a press, point defects such as minute sharp dents and wrinkled line defects are likely to occur on the face surface of a panel used as a screen or an image display portion. Therefore, in order to remove these defects and secure the optical surface quality, the panel face is usually polished.

As a method of polishing a face of a glass panel, there is known a method of polishing a disk-shaped polishing tool while rotating the center of the disk as a rotation axis. As this disk-shaped polishing tool, a concave disk-shaped polishing tool made of rubber or felt and having a predetermined curvature is used. The disc-shaped polishing tool is pressed against the surface of the face glass panel and polished (hereinafter referred to as a lapping method).

The polishing tool used in this lapping method is used by attaching a flexible polishing pad made of rubber or felt to a holder having rigidity such as aluminum. If the face curvature of the glass panel to be polished is a spherical surface having a single curvature, this polishing tool can perform uniform polishing by using the holder by matching the curvature of the glass panel with the curvature of the face of the glass panel.

[0005]

However, in recent years, in order to improve the display quality of the face surface of a glass panel, the face curvature has changed to a so-called aspherical panel in which a plurality of curvatures are combined. In that case, the conventional lapping apparatus as described above has a problem in that the face surface is distorted due to uneven polishing.

This is because it is impossible to always match the curvature of the polishing tool and the curvature of the glass panel with each other during the polishing due to the relative rotation of the polishing tool and the glass panel. Therefore, there is a problem in that the face surface cannot be uniformly polished, and the face surface is likely to be distorted due to the uneven polishing. Here, the distortion of the face surface is a portion in which the curvature of the face surface changes discontinuously, and causes distortion of the display image.

The distortion of the displayed image is inspected by reflecting the straight tube fluorescent lamp arranged at the back on the face surface and observing the reflected image obliquely from the front to see if the linear portion of the fluorescent lamp is distorted. be able to. In order to alleviate this uneven polishing, various measures have been taken such as attaching the polishing pad to the polishing holder via a flexible sponge, but the effect was not sufficient.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned drawbacks, and a disk-shaped polishing tool having a concave curved surface on a glass panel for a cathode ray tube placed on a rotating table. In a polishing method of polishing the glass panel surface by pressing while rotating about its central axis, a disc-shaped polishing tool is used as a rotation center with a point on an arbitrary straight line substantially orthogonal to its rotation axis as the line segment. The present invention provides a method for polishing a glass panel for a cathode ray tube, which is characterized by reciprocating in an arc shape in a plane including.

Further, it has a table which rotates at a predetermined speed, and a glass panel for a cathode ray tube is placed on this rotating table, and a disk-shaped polishing tool having a concave curved surface is centered on the center axis of the glass panel. In a polishing device that presses while rotating to polish the surface of a glass panel, a disc-shaped polishing tool is rotated about a point on an arbitrary straight line substantially orthogonal to its rotation axis, and an arc shape is formed in a plane including the line segment. The present invention provides a polishing device for a glass panel for a cathode ray tube, which is characterized by having a reciprocating mechanism.

Further, the distance R between the center of the disk-shaped polishing tool and the center of rotation of the arcuate reciprocating motion is 200 mm≤R≤150.
0 mm, the central angle θ of the circular motion of the disk-shaped polishing tool is 2 to 30 °, and C = (2πRθ) /
Movement amount C of circular arc motion of disk-shaped polishing tool calculated in 360
Is 20 mm ≤ C ≤ 300 mm, and 0.05 D ≤ C ≤ 0.5 D with respect to the short side length D of the glass panel. is there.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the face surface of a glass panel for a cathode ray tube is polished using a rotating disc-shaped polishing tool. This basic structure is the same as that of the conventional polishing apparatus. In the present invention, while rotating this disk-shaped polishing tool,
Not only the table on which the glass panel is placed is rotated, but also the aspherical panel can be polished with less distortion by swinging the disk-shaped polishing tool with respect to the center of the rotary table.

The details of the present invention will be described below. FIG.
A plan view of a typical lapping apparatus as an embodiment of the present invention is shown in FIG. FIG. 2 shows a side view thereof.

The glass panel 2 is placed on the rotary table 3, and the motor 10 rotates the table 3 at a predetermined rotational speed. This rotation speed is preferably in the range of 5 to 100 rpm, particularly preferably in the range of 10 to 50 rpm. 5 rp
If it is less than m, the polishing efficiency tends to decrease, and if it exceeds 100 rpm, it becomes difficult to fix the glass panel, and it is not advantageous because a large capacity motor is required. The number of rotations may be appropriately determined in each device with reference to the above range, taking into consideration the size of the glass panel to be polished, the polishing time, and the like.

A concave disk-shaped polishing tool 1 is arranged above the rotary table 3. The disc-shaped polishing tool 1 is pressed against the face surface of the glass panel 2 while rotating with a straight line orthogonal to the center of the disc as a rotation axis. The diameter A of the disk-shaped polishing tool 1 is determined according to the size of the glass panel to be polished. Generally, the diagonal diameter B of the glass panel face surface
However, the range of B ≦ A ≦ 1.5B is preferable.

The curvature of the disk-shaped polishing tool 1 may be determined according to the approximate curvature when the diagonal direction of the face surface is approximated to a single curvature. In many cases, there is a single curvature, but there are also cases where there are a plurality of curvatures that are changed in the radial direction. The polishing pad is fixed to the polishing tool holder via a flexible elastic member such as sponge having a thickness of about 20 to 50 mm.
The polishing tool holder is usually disc-shaped and may be made of a rigid material such as aluminum.

The number of rotations of the disk-shaped polishing tool 1 may be appropriately determined depending on the performance of the apparatus and the size of the glass panel to be polished, but usually, the range of 100 to 1000 rpm is preferable,
A range of 300 to 800 rpm is particularly preferred. 100r
If it is less than pm, the peripheral speed of the disk-shaped polishing tool tends to be low, and the polishing efficiency tends to be low. If it exceeds 1000 rpm, vibration tends to occur, and uniform polishing tends to be difficult.

The polishing pad is an elastic member, and specifically, the material is rubber or felt. The disk-shaped polishing tool is pressed against the face surface of the glass panel with a predetermined pressure. This pressure needs to be adjusted depending on the material of the polishing pad, the thickness of the glass panel, and the strength, but is preferably in the range of about 0.1 to 5 kg / cm ² . If the pressure exceeds 5 kg / cm ² , problems such as breakage of the glass panel are likely to occur.

The disk-shaped polishing tool 1 is fixed to the rotary shaft 4 to which the power of the motor 5 is transmitted by screws or the like. The motor 5 and the rotary shaft 4 are fixed to a support frame 6, which is installed on a rotary shaft 8 on a base structure 7 of the polishing machine. This motor 5 is arranged on the opposite side of the disk-shaped polishing tool 1 so that the end on the disk-shaped polishing tool 1 side does not become heavy, but if there is a lighter drive mechanism, the rotation shaft of the disk-shaped polishing tool 1 It is also possible to directly connect to 4 and arrange.

According to the present invention, the support frame 6 has a structure capable of reciprocating in an arc shape with respect to the base structure with the rotating shaft 8 as the center of rotation. The distance R between the center of rotation and the rotation axis of the disk-shaped polishing tool depends on the size of the glass panel to be polished, but is usually 200 mm ≦ R ≦ 1500.
The range of mm is preferred.

If R <200 mm, the dimensional margin is likely to be lost when the polishing apparatus is manufactured, and it becomes difficult to manufacture the polishing apparatus. When 1500 mm <R, the locus of the reciprocating motion of the disk-shaped polishing tool is close to a straight line, and therefore the effect of alleviating the local distortion that occurs during polishing of the face surface of the glass panel is not sufficient.

Generally, the polishing apparatus does not polish a specific size, but often polishes a plurality of sizes of glass panels. Therefore, normally, the distance R is set within the above range, and the disc-shaped polishing tool 1 and the rotary table 3 used when polishing the maximum size thereof are set to a distance that does not touch the base structure 7 of the polishing machine.

In the present invention, the disk-shaped polishing tool is moved in an arc around the rotary shaft 8. The turning central angle θ is 2
A range of -30 ° is preferable, and the movement amount C of the disk-shaped polishing tool is C = (2πRθ) / 360, and 20 mm ≦ C ≦ 300.
The range of mm is preferred. If it is less than 20 mm, the effect of alleviating the distortion of the face surface is too small to be practical. On the other hand, when it exceeds 300 mm, the disc-shaped grinder has a large protrusion from the panel during polishing, the pressure distribution between the disc-shaped grinder and the face surface becomes non-uniform, and the face surface is easily distorted. It is not preferable because the polishing efficiency is lowered.

Further, the moving amount C of the disk-shaped polishing tool is 0.05D ≦ where D is the short side length of the glass panel.
C ≦ 0.5D is also satisfied. This is 0.05
When it is less than D, the effect of alleviating the distortion of the face surface is small. On the other hand, if it exceeds 0.5 D, the distortion of the face surface is likely to occur and the polishing efficiency is lowered.

The mechanism for rotating the disc-shaped polishing tool 1 in an arc shape is composed of an electric motor 9 with a reduction gear fixed to a base structure 7 of the polishing machine, and an eccentric plate 11 attached to its output shaft. ing. The rotation of the eccentric plate 11 serves as a power source for the arcuate reciprocating motion of the support frame. The cycle of reciprocating motion is controlled by the rotation speed of the motor 9.

Since the support frame 6 and the disk-shaped polishing tool 1 have a large inertia, it is not suitable to operate at a very high speed in view of the apparatus. Therefore, the range of 1 to 50 cycles / minute is appropriate. The moving amount of the reciprocating motion of the disk-shaped polishing tool is the eccentric plate 11
Adjust according to the amount of eccentricity. This arc-shaped reciprocating mechanism can utilize not only the structure of the eccentric plate and the motor but also reciprocating motion of pneumatic or hydraulic cylinders, and the disk-shaped polishing tool can be rotated in an arc shape within the above range. It should be done like this. Reference numeral 12 is a hydraulic cylinder for moving the disk-shaped polishing tool up and down and adjusting the pressure applied to the glass panel.

Regarding the abrasive, a method of polishing while applying a slurry containing abrasive grains to the contact portion between the abrasive and the face surface, and a method of polishing using an abrasive tool made of a material containing abrasive grains However, either method may be used.

When the disk-shaped polishing tool is reciprocally moved in an arc shape, it is impossible to completely remove the nonuniformity of the face surface due to the lapping, but it is possible to visually observe the local area of the glass face surface. It is possible to significantly reduce the target distortion.

The local distortion of the glass face surface visually observed is that the local part of the disk-shaped polishing tool (often the inner peripheral part or the outer peripheral part of the polishing pad) exerts a high pressure on the face surface of the glass panel. It is thought that this occurs due to the contact with and the same trajectory taken during polishing. By reciprocating the lapping tool in an arc shape, the width of its locus can be widened, so that the deviation of polishing due to this same locus can be alleviated and a glass panel with good display quality can be obtained. You can

The glass panel thus polished was combined with a funnel with a neck tube, which was separately manufactured, and further coated with a phosphor, a shadow mask,
A glass cathode ray tube is made by combining an aperture grill.

[0030]

【Example】

Example A substantially rectangular 20-inch aspherical glass panel 2 having an aspect ratio of 3: 4, a diagonal diameter of 514 mm, and an approximate curvature at a diagonal position of the face surface of 800 mm was prepared. This was placed on the rotary table 3 of the polishing apparatus having the configuration shown in FIGS. 1 and 2 so that the glass panel would not move so that the panel center coincided with the center of rotation of the table. On the other hand, the diameter of the rotating shaft 4 is 53
A concave disk-shaped polishing tool 1 having a diameter of 0 mm and a curvature of 820 mm was attached. A rubber-made polishing pad attached via a sponge having a thickness of 20 mm was used as the disc-shaped polishing tool.

The rotary table 3 was rotated at 15 rpm, and the disk-shaped polishing tool 1 was rotated at 800 rpm. Further, the support frame 6 and the disk-shaped polishing tool 1 were reciprocally rotated about the rotation axis 8 at 12 cycles / minute. The distance between the center of the disk-shaped polishing tool and the center of rotation of this polishing apparatus was 800 mm, and the rotation angle (center angle of arc movement) was 8 °.

From the center of the polishing tool, the average particle size is 60 μm.
While applying the mum slurry, the polishing tool was pressed against the glass panel from above with a force of 500 kg, and the glass panel was polished for 120 seconds.

Further, another similar polishing apparatus equipped with a polishing tool having a felt polishing pad was prepared. The glass panel that had been subjected to the pumice polishing was placed on the rotary table of this polishing device so as not to move. Then
While the slurry of cerium oxide having an average particle diameter of 2.5 μm was applied from the center of the polishing tool, the polishing tool was pressed against the glass panel from above with a force of 500 kg, and the glass panel was similarly polished for 120 seconds.

When a straight tube fluorescent lamp was reflected on this polished glass panel and the reflected image was visually observed, a good polished surface with no conspicuous distortion was obtained. In this example, a glass panel having an aspect ratio of 3: 4 was polished, but an aspect ratio of 9: 1 was used.
The same effect can be obtained by using the glass panel of No. 6.

Comparative Example As a polishing apparatus, a conventional lapping apparatus having a mechanism in which a disk-shaped polishing tool only rotates about the center thereof is used. FIG. 3 shows a side view of the conventional lapping apparatus.
The reference numerals of the respective parts of the apparatus are the same as those in FIG. Basically, the electric motor 9 and the eccentric plate 1 shown in FIG.
It is a device without 1.

Similar to the embodiment, a substantially rectangular 20-inch aspherical glass panel 2 having an aspect ratio of 3: 4, a diagonal diameter of 514 mm, and an approximate curvature of a diagonal position of the face of 800 mm is not moved on this rotary table. So that it was placed. The same polishing tool as in Example 1 was used. The glass panel was polished under the same conditions as in the examples with respect to the number of table rotations, the number of rotations of the disk-shaped polishing tool, the pressing force of the disk-shaped polishing tool, and the abrasive.

When a straight tube fluorescent lamp was reflected on a polished glass panel and the reflected image was visually observed, an arc-shaped distortion was generated on the face surface at the position shown in FIG. 4, and the outer periphery of the disk-shaped polishing tool was found. It is thought that this was caused by the local hitting of some parts.

[0038]

According to the present invention, when lapping a glass panel for a cathode ray tube, it is possible to reduce the occurrence of distortion of the aspherical panel on the face surface. Therefore, the pressing force of the polishing tool can be increased, the polishing efficiency can be increased, and the polishing time can be shortened, thereby improving the productivity. The present invention can be applied in various ways within a range that does not impair the effects of the present invention.

[Brief description of drawings]

FIG. 1 is a plan view of a lapping apparatus according to a representative embodiment of the present invention.

2 is a side view of the example of FIG.

FIG. 3 is a side view of a lapping apparatus of a comparative example.

FIG. 4 is an explanatory view of distortion of a face surface of a glass panel polished by a polishing device of a comparative example.

[Explanation of symbols]

 1: Disk-shaped polishing tool 2: Glass panel 3: Rotary table 4: Rotary shaft 5: Motor 6: Support frame 7: Polishing machine base structure 8: Rotating shaft, 9: Motor 10: Motor 11: Eccentric plate 12: Hydraulic pressure cylinder

Claims (3)

[Claims] 1. A polishing method for polishing a glass panel surface by pressing a disk-shaped polishing tool having a concave curved surface against a glass panel for a cathode-ray tube mounted on a rotating table while rotating the glass panel around the central axis. Polishing a glass panel for a cathode ray tube characterized by reciprocally moving a disk-shaped polishing tool in an arc shape in a plane including the line segment with a point on an arbitrary straight line substantially orthogonal to the rotation axis as a rotation center. Method. 2. A cathode ray tube glass panel is mounted on the rotary table having a table that rotates at a predetermined speed, and a disk-shaped polishing tool having a concave curved surface is centered on the center axis of the glass panel. In a polishing device that presses while rotating to polish the surface of a glass panel, a disc-shaped polishing tool is rotated about a point on an arbitrary straight line substantially orthogonal to its rotation axis, and an arc shape is formed in a plane including the line segment. An apparatus for polishing a glass panel for a cathode ray tube, characterized in that it has a mechanism for reciprocating. 3. The distance R between the center of the disk-shaped polishing tool and the center of rotation of the circular arc-shaped reciprocating motion is in the range of 200 mm ≦ R ≦ 1500 mm, and the central angle θ of the circular motion of the disk-shaped polishing tool is 2.
The movement amount C of the circular arc motion of the disk-shaped polishing tool in the range of -30 ° and C = (2πRθ) / 360 is 20 m.
3. The glass panel polishing apparatus for a cathode ray tube according to claim 2, wherein m ≦ C ≦ 300 mm and 0.05D ≦ C ≦ 0.5D with respect to the short side length D of the glass panel.