JP3272228B2 - Cathode ray tube dividing device and cathode ray tube dividing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube (CR)
The present invention relates to a cathode ray tube splitting apparatus and a cathode ray tube splitting method which are optimally used when disassembling and processing T).

[0002]

2. Description of the Related Art In recent years, recycling of resources and prevention of environmental destruction have been highlighted. In response to this request,
Research on the reuse of cathode ray tubes (CRTs, cathode ray tubes) of used television sets is progressing in various fields.
Cathode ray tubes are used in television sets and other display devices and the like, and the cathode ray tube has a panel portion and a funnel portion. The panel portion is made of a substantially transparent glass material, and the funnel portion is made of a glass material mixed with lead. The funnel portion and the panel portion are formed in a tubular shape by welding with frit glass (solder glass).

[0003] The cathode ray tube is externally provided with an electron gun, a deflection yoke and the like on the back side. An aperture grill (or shadow mask) is provided inside the cathode ray tube.
Blue and green phosphors are regularly applied. An explosion-proof band is attached to a portion where the panel portion and the funnel portion are welded together through an explosion-proof tape. The panel part and the funnel part of the cathode ray tube, particularly the panel part, are made of a glass material, so that they are relatively easy to reuse. For this reason, when reusing a cathode ray tube,
In particular, there is an attempt to cut the panel from the cathode ray tube and reuse it. For example, a method has been proposed in which a panel portion and a funnel portion are divided by scratching four corner portions (corner portions) of the side surface of a cathode ray tube and thereafter heating the same. In this division method, the four corners of the cathode ray tube are scratched, and a heater wire is applied from four sides around the side of the cathode ray tube to generate thermal distortion, and cracks run from the four corners of the cathode ray tube to the sides. This divides the panel and funnel.

[0004]

FIG. 13 shows an example of the above-mentioned conventional dividing method. A groove 300 has already been formed in the corner portion CN of the cathode ray tube for cutting the funnel portion F and the panel portion PA of the cathode ray tube.
When the heater wire hits the side periphery SC of the cathode ray tube, thermal distortion occurs on the side periphery SC. However, simply applying the heater wire to the side periphery (long side portion or short side portion) does not occur. Since the thermal distortion of the central portion CT around the side surface (side) is smaller than the thermal distortion of the other portion CH near the groove 300, the crack CC generated from the corner portion CN does not reach the central portion CT. Crack progress stops. Therefore, it is necessary to wait for a long time until a crack is generated by the center CT, or to destroy the center CT using a tool such as a metal fitting so that the center CT is cracked. Therefore, there is a problem that the cathode ray tube cannot be divided into a panel portion and a funnel portion in a short time. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a cathode ray tube dividing apparatus and a cathode ray tube dividing method which can surely divide a cathode ray tube in a short time.

[0005]

According to the present invention, there is provided a cathode ray tube dividing apparatus for dividing a cathode ray tube into a panel portion and a funnel portion, and a supporting means for supporting the cathode ray tube; A groove forming means for forming a dividing groove at a corner of the cathode ray tube supported by the support means, and a substantially central portion of the periphery of a side surface of the cathode ray tube is heated for a predetermined time and a thermal strain is formed at the substantially central portion. And a heating means for heating the entire circumferential direction around the side surface of the cathode ray tube to apply thermal distortion to the entire circumferential direction around the side surface of the cathode ray tube.

In the present invention, the support means supports the cathode ray tube. The groove forming means forms a dividing groove at a corner of the supported cathode ray tube. Then, the heating means heats a substantially central portion of the periphery of the side surface of the cathode ray tube for a predetermined time, and gives a thermal strain to a portion including the substantially central portion. Further, the heating means heats the entire circumferential direction around the side surface of the cathode ray tube to apply thermal distortion to the entire circumferential direction around the side surface of the cathode ray tube. In this way, when the cathode ray tube is divided into the panel portion and the funnel portion, the central portion of the periphery of the side surface of the cathode ray tube where cracks are unlikely to be cracked is heated for a predetermined time first, and then the entire circumferential direction around the side surface is Is heated, cracks occur at once in the periphery of the side surface of the cathode ray tube, and the operation of dividing the cathode ray tube into a panel portion and a funnel portion can be performed in a short time and reliably.

[0007]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention,
Although various technically preferable limits are given, the scope of the present invention is not limited to these modes unless otherwise specified in the following description.

FIG. 1 is a front view showing a preferred embodiment of a cathode ray tube splitting device according to the present invention. FIG. 2 is a perspective view showing the apparatus for dividing the cathode ray tube of FIG. In FIGS. 1 and 2, the splitting device of the cathode ray tube includes a support unit 10, a groove forming unit 50, a heating unit 70, a positioning unit 90, and a control unit 1.
00 and the like. The supporting means 10 includes the vertical movement mechanism 1
1, a rotating unit 12, a suction unit 13, a support plate 24, and the like.

The vertical movement mechanism 11 includes a fixed plate 16 fixed to the fixed portion 15, a support plate 17 and the guide bar 1.
8, 18 and the like. The fixed plate 16 is fixed to the fixed portion 15, and the bearings 16 a, 16 a of the fixed plate 16 are fixed.
Can guide the guide bars 18, 18 so as to be able to move up and down in the arrow Z direction. The support plate 17 includes the guide bar 1
It is fixed to the upper ends of 8,18. The support plate 17 supports a motor 19 of a rotating means 12 with a built-in rotor. The operating means 20 is a multi-stage positioning cylinder capable of moving the vertical shaft 21 up and down in the arrow Z direction.
The upper end of 1 is fixed to the center position of the support plate 17. Therefore, when the control unit 100 operates the operation means 20,
The support plate 17 can be moved up and down and positioned in the arrow Z direction.

The rotating means 12 is mounted on a support plate 17, and the rotating means 12 is capable of rotating the cathode ray tube 200 together with the support plate 24 in the direction of arrow R. The rotation means 12 can change the rotation speed of the cathode ray tube 200. The rotating means 12 is a motor in which a rotor 12a is arranged inside a stator 12b, and the rotor 12a is connected to a shaft 22. When the coil of the stator 12b of the motor 19 is energized, the magnetic flux generated by the coil interacts with the magnetic flux of the magnet of the rotor 12a, and the rotor 12a rotates together with the shaft 22. A vacuum suction pad 23, preferably made of an elastic member, is attached to the shaft 22. The vacuum suction pad 23 can suck and hold the surface of the panel portion 210 of the cathode ray tube 200 firmly by the suction action of the suction means 24a. A spring 25 is disposed between the member 22a of the shaft 22 and the support plate 24. The support means 10 has a support plate 24 and four support pins 14. The support pin 14 is a member that supports the surface of the panel section 210, and is preferably made of a slippery plastic or metal (for example, iron).
Make sure that 10 is not scratched.

Next, the positioning means 90 will be described.
The positioning means 90 shown in FIG.
93 and 94 are provided. These pads 91, 92,
Numerals 93 and 94 are made of iron, for example, and can press the side surfaces 220, 221, 222 and 223 of the four sides of the cathode ray tube 200, respectively. That is, each pad 9
1,92,93,94 are cylinders 95,96,97,
98, for example, around four sides 220, 221,
222, 223, or around the four sides 22
0, 221, 222, and 223.

For example, when the cylinders 95 and 97 shown in FIG. 2 are operated to push the pads 91 and 93 toward the cathode ray tube 200, the pads 91 and 93 are turned around the long sides 220 and 222 of the four sides of the cathode ray tube 200. Is pressed, and the cathode ray tube 200 is positioned on the support means 10 in the arrow X direction. Similarly, cylinders 96, 98
Is activated, the pads 92 and 94 are pressed against the short sides 221 and 223 of the short side of the cathode ray tube 200, so that the cathode ray tube 200 is positioned on the support means 10 along the arrow Y direction. The cathode ray tube 200 is a motor 1
Since the centering is performed on the support means 10 in the Y direction of X by four pads 91 to 94 indexed by 180 degrees by 9, the vacuum suction pad 23 of the suction unit 13 in FIG. 210
Can be properly suctioned at the central portion of

Next, the heating means 70 will be described. The heating means 70 includes four heater wires 71, 72, 73, 74, a heating power supply 75, and the like, as shown in FIGS. Each of the heater wires 71 to 74 generates heat when a current is supplied from a heating power supply 75. These heater wires 71
Can be made by twisting three nichrome wires, for example, and are mutually insulated by an insulating layer. By doing so, it is possible to prevent the heater wire 71 from being cut. The heater wire 71 corresponds to the periphery 220 of the long side of the cathode ray tube 200, the heater wire 72 corresponds to the periphery 221 of the short side of the cathode ray tube 200, and the heater wire 73 corresponds to the periphery of the long side of the cathode ray tube 200. 222, and the heater wire 74 corresponds to the periphery 223 of the short side of the cathode ray tube 200. That is, these four heater wires 71 to 74 are arranged in a substantially rectangular shape when viewed from above.

The construction of the heating means 70 of FIG. 1 is shown in more detail in FIG. The heating means 70 includes four operating means 501, 502, 503, 504 for operating the four heater wires 71, 72, 73, 74 as described above. These operation means 501 to 504 have the same structure. Operation means 501, 502, 503,
Reference numeral 504 denotes that the heater wires 71, 72, 73, 74 are respectively brought closer to the cathode ray tube 200 side, or
It has a function to exit from the side. Operating means 501-
Since 504 has the same structure, the structure will be described using the operation means 501 as an example. The operation unit 501 is a stage 600
And a stage 601. The stage 600 includes a rail 602 and a motor 603. Stage 60
1 includes arms 610 and 610 and two actuators 6
12,612. Motor 6 of stage 600
03 turns the stage 60 by turning the feed screw 620.
1 can be positioned by moving it in the direction of arrow X. That is, the stage 601 is located around the long side of the cathode ray tube 200.
20 and can be advanced or retracted.

The arm 6 provided on the stage 601
10, 610 are rotated in the direction of arrow J by the operation of the actuators 612, 612. Rollers 700, 70 are provided on the free end side of the arm 610.
0 is attached. These rollers 700, 700
Is made of an insulating material such as ceramics. These rollers 700, 700
And the heater wire 71 is brought into contact with the periphery 220 of the long side surface. The operation means 502
The heater wire 72 can be brought into or out of contact with the side periphery 221 of the cathode ray tube 200. Similarly, the operating unit 503 can make the heater wire 73 abut or move away from the side periphery 220 of the cathode ray tube 200. The operating means 504 can make the heater wire 74 abut or move away from the side periphery 223 of the cathode ray tube 200.

Next, the groove forming means 50 of FIG. 1 will be described. As shown in FIG. 3, two groove forming means 50 are provided, and are arranged at diagonal positions of the cathode ray tube 200. Each groove forming means 50 includes a motor 51 as shown in FIG.
, Motor 52, arms 53, 54 and rotary grindstone 5
5 and so on. The motor 51 is attached to a fixed portion 56 as shown in FIG. 1, and moves the arms 53 and 54 and the rotary grindstone 55 toward and away from the cathode ray tube 200. The output shaft of the motor 51 in FIG. 4 is attached to one end of the arm 53. The other end of the arm 53 is rotatably connected to one end of another arm 54. A motor 52 is provided at the other end of the arm 54, and an output shaft of the motor 52 is connected to a rotating grindstone 55. When the motor 52 is operated, the rotary grindstone 55 continuously rotates in the C1 direction.

A spring 57 is mounted between the arm 53 and the arm 54. Thus, when the motor 51 rotates, the arm 53 and the arm 54 rotate in the direction of arrow C3, and when the motor 52 rotates, the rotating grindstone 55 rotates. In addition, as shown in FIG.
Is applied to the peripheral sides 220 and 222 of the long side or the peripheral sides 221 and 223 of the short side. It rotates in the direction of arrow C2 with respect to 53. The suction means 24a and the motor 1 shown in FIG.
9, operation means 20, heating power supply 75, motors 51, 5
2. The motor 603 and the actuator 612 in FIG.
The control unit 100 of FIG. 1 controls.

Next, a method of dividing a cathode ray tube using the above-described cathode ray tube separating apparatus will be described. First, in response to a command from the control unit 100 shown in FIG.
The transport section 310a of the 00a transports the cathode ray tube 200 to the cathode ray tube separation device as shown in FIG. The suction vertical movement means 300a and the transport section 310 are provided with the cathode ray tube 2
00 on the support pin 14 of the support means 10 and the cathode ray tube 200 is placed substantially on the support pin 14.
The suction operation of 00 a is stopped, and the suction vertical movement means 300 a and the transport unit 310 are separated from the cathode ray tube 200. The cathode ray tube 200 thus transported has already been removed from the electron gun, the deflection yoke and the like, and the explosion-proof band and the like have also been removed. The cathode ray tube 200 has the funnel section 211 facing upward, and the panel section 210 includes the support pin 14 and the suction section 13.
Is supported by the vacuum suction pad 23.

Next, the centering pads 91, 92, 93, and 94 shown in FIG. 2 are operated by operating the cylinders 95, 96, 97 and 98 in accordance with a command from the control unit 100. 222 or perimeter of short side 22
It hits so that it may be intermittently sandwiched between 1,223. By repeating this operation, the cathode ray tube 200 is centered or centered with respect to the support means 10. From this, the center of rotation of the cathode ray tube 200 and the center of rotation of the support plate 24 coincide. At this time, the suction means 24 of the vacuum suction pad 23 is operated, and the vacuum suction pad 23
Vacuum-adsorbs the surface of the cathode ray tube 200 and firmly fixes it.

Next, the operation means 20 of the vertical movement mechanism section 11 shown in FIG. 1 is operated by a command from the control section 100, whereby the vertical shaft 21 and the support means 10 are raised. This raises the cathode ray tube 200 to the first position PL at the rising end.
Stop at 1. The rotary grindstone 55 of the groove forming means 50 of FIGS. 1 and 3 moves to a position corresponding to the dividing line indicated by the arrow LL of the cathode ray tube 200 of FIG. The LL line is located closer to the surface of the panel section 210 than the aperture grill 230. By cutting the cathode ray tube 200 with the LL line, the cathode ray tube 200 A funnel section 211 including a pin 231;
Panel section 210 without aperture grille and pins
Can be completely divided.

Therefore, in order to divide the cathode ray tube 200 in this way, the motor 51 is operated and the rotary grindstone 55 is close to the corner portion (also called a corner) CD as shown in FIG. First, grooves (also referred to as flaws) 300 are formed at the corners CD at the four corners of the cathode ray tube 200 along the line LL in FIG. 1 as shown in FIGS. Specifically, as shown in FIG.
While being rotated in the direction of arrow C1 by the operation of 2, the spring 57 urges the periphery of the side surface of the cathode ray tube 200. Therefore, each rotary grindstone 55 can be reliably applied to the corner portion CD along the line LL of the cathode ray tube 200 as shown in FIG. When the cathode ray tube 200 is rotated in the direction of arrow T as shown in FIG. 3 by rotating the rotor 12a of the motor 19 of the rotating means 12 of FIG. 1, a rotating grindstone 55 is provided at the four corners CD of the cathode ray tube 200. Since it follows, a dividing groove 300 can be formed as shown in FIGS. When the grooves 300 are formed in the cathode ray tube 200 with the rotary grindstone 55, so-called dry grinding is performed without using grinding oil.

Then, as shown in FIG. 1, the motor 51 operates to return the rotary grindstone 55 of the groove forming means 50 to the origin position, and the rotation of the cathode ray tube 200 also stops. The operation means 20 of the vertical movement mechanism unit 11 in FIG. 1 is operated, and the cathode ray tube 200 is positioned down from the first position PL1 to the second position PL2. In this state, the cathode ray tube 200 is oriented as shown in FIG. That is, the long sides 220 and 222 of the long sides face the heater wires 71 and 73, and the short sides 221 and 223 of the short sides face the heater wires 72 and 74.

As shown in FIG. 8 and FIG.
1, 502, 503, 504 stages 601 correspond to the side surfaces 220, 221, 222,.
Proceed so as to approach 223. That is, the stage 601 of the operation unit 501 and the stage 6 of the operation unit 503
01 advances so as to approach along the arrow X direction, and the stage 601 of the operation means 502 and the stage 601 of the operation means 504 advance so as to approach along the arrow Y direction.
Thereby, the heater wires 71, 72, 73, 74 supported by the rollers 700, 700 as shown in FIG. 10 abut against the central portions CP of the side surfaces 220, 221, 222, 223. The heating power supply 75 of FIG. 2 supplies a predetermined current to each of the heater wires 71 to 74, so that each of the heater wires 71 to 74 generates heat and heats the central portion CP of FIG. . In other words, four sides around 22
The central portions CP of 0, 221, 222, and 223 are first heated by the heater wires 71 to 74 for a predetermined time. Thereafter, the heater wires 71 to 74 are connected to the actuator 61 of FIG.
The gap between the rollers 700 and 700 in FIG. 8 is gradually opened by the operation of the rollers 2 and 612. As shown in FIG. 11, the heater wires 71 to 74 are all around the central portion CP of the side periphery 220 to 223. Will be abutted over. At this time, the speed at which the heater wires 71 to 74 come into contact with each other is reduced. Stop and 2 around the side by heater wires 71-74.
20 to 223 are heated along the line LL in FIG.

As a result, a temperature difference occurs between the inside and the outside of the cathode ray tube 200, causing internal distortion. Therefore,
As shown in FIG. 8, a crack CC is formed from a corner portion CD having many grooves 300 having a large distortion, and a crack is also formed in a central portion CP.
The division into the 0 and the funnel section 220 can be performed reliably and in a short time. In this way, since the heater wire first heats the central portion CP around the side surface and then heats the entire periphery around the side surface, it is possible to reliably connect the cracks generated inside the panel portion and to surely divide the panel portion. Can be performed. In other words, it is possible to eliminate the uncertainty of the division due to the fact that the conventional panel does not connect the split, and it is possible to improve the yield of the division of the cathode ray tube.

The present invention is not limited to the above embodiment. For example, in the embodiments shown in FIGS. 8 to 11, grooves 300 are formed only in the corner portions CD of the side surfaces 220 to 223 of the cathode ray tube 200. However, the present invention is not limited to this. As shown in FIG. 12, the groove forming means 50, 50 of FIG.
After forming a continuous groove 300 over the entire circumference of 0, 221, 222 and 223, FIGS.
Similarly, the heater wire may be applied over the entire length of the groove 300. In this case, by setting the width W of the groove 300 to be larger than the diameter D of the heater wires 71 to 74 as shown in FIG.
0, and the division by heating becomes easy. FIG.
The other points of the second embodiment are almost the same as those of the embodiment of FIG. 8, and the description thereof will be omitted.

In the illustrated embodiment described above, the heater wires 71 to 74 are connected to the side periphery 220 of the cathode ray tube 200.
When a certain current starts to flow when a part (center portion) of the heater wires 71 and 223 starts to contact with each other, the rollers 700 and 700 shown in FIG.
74 are in contact with and heated over the entire length of the side surfaces 220 to 223. Not limited to this, the heater wires 71 to 74 may be connected to the side surfaces 220 to 22 of the cathode ray tube 200.
8 is heated by flowing an electric current for a predetermined time, and then the rollers 700, 700 shown in FIG.
As a matter of course, 74 may be stopped by contacting the side surfaces 220 to 223 as shown in FIG.

In the above-described embodiment, the side surfaces 220 to 220
Since the central portion CP of the 223 has a convex shape, the portion around the central portion CP is heated first. It is also possible to form a groove having a certain length (the length can be freely set) only in the corner portions CD at the four corners of the cathode ray tube, and fit the heater wire into the groove. The groove forming means uses a rotary grindstone. As the rotary grindstone, for example, an electroformed or electrodeposited artificial diamond grindstone can be used. However, the present invention is not limited to this, and it is of course possible to use other types of cutter grindstones to scratch the periphery of the side surface of the cathode ray tube. Further, in the embodiment shown in FIG. 3, two groove forming means 50, 50 are arranged to form a groove at once with the cathode ray tube sandwiched from both sides. However, the present invention is not limited to this, and one or more groove forming means may be provided. Three or more can also be arranged.
The cathode ray tube is not limited to a cathode ray tube for a television set, and a cathode ray tube for a measuring instrument and the like can be divided by the cathode ray tube dividing device of the present invention.

In the embodiment of the present invention, a groove is provided on the outer periphery of the cathode ray tube, and a heater wire is inserted into all of the groove to heat and apply thermal strain to cut the tube. And the funnel portion can be divided in a short time, and the reliability of dividing the panel portion and the funnel portion is greatly improved. Also, for example, in contrast to the conventional case where four cutters are required to simultaneously scratch the four corners of the cathode ray tube, in the embodiment of the present invention, the use of two groove forming means 50, 50 suffices. In addition, the configuration of the processing apparatus can be simplified. Further, as shown in FIG. 2, the positioning means 90 includes two positioning cylinders 91a and 92 made of iron, for example.
a, 93a, 94a and the cylinders 95 to 98 may be combined. As a result, although the side surfaces 220 to 223 are curved, the cathode ray tube 200 can be correctly positioned even in this case.

[0029]

As described above, according to the present invention,
The cathode ray tube can be reliably divided in a short time.

[Brief description of the drawings]

FIG. 1 is a front view showing a preferred embodiment of a cathode ray tube splitting device according to the present invention.

FIG. 2 is a perspective view showing a device for dividing the cathode ray tube of FIG. 1;

FIG. 3 is a plan view showing a state in which a groove is formed in a corner around the side surface of the cathode ray tube.

FIG. 4 is a perspective view showing an example of a groove forming means for forming a groove around the side surface of the cathode ray tube.

FIG. 5 is a diagram in which a rotating grindstone of a groove forming unit attempts to form a groove in a corner portion of a cathode ray tube.

FIG. 6 is a perspective view showing an example of a cathode ray tube in which a groove is formed in a corner portion around a side surface.

FIG. 7 is a sectional view showing a corner portion of the cathode ray tube.

FIG. 8 is a perspective view showing the structure of the heating means of FIGS. 1 and 2 in detail.

FIG. 9 is a plan view showing a state in which a groove is formed in a corner portion of the cathode ray tube.

FIG. 10 is a diagram illustrating a state in which a heater wire is pressed against a central portion around a side surface of a cathode ray tube.

FIG. 11 is a diagram showing a state in which a heater wire is pressed substantially all around the side surface of the cathode ray tube.

FIG. 12 is a perspective view showing a heating means and the like showing another embodiment of the present invention shown in FIG. 8;

FIG. 13 is a side view showing an example of a cathode ray tube to be divided according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Support means 11 Vertical movement mechanism part 12 Rotation means 13 Suction part 50 Groove formation means 70 Heating means 71-74 Heater wire 90 Positioning means 100 Control means 200 Cathode ray tube 210 Panel part 211 Funnel part 220-223 Side periphery 300 groove

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroyuki Ishii 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Akito Fukuya 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo (56) References JP-A-49-57765 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C03B 33/06 C03B 33/10 H01J 9/50 C03B 33/095

Claims (9)

(57) [Claims] 1. A cathode ray tube splitting device for splitting a cathode ray tube into a panel portion and a funnel portion, comprising: a supporting means for supporting the cathode ray tube; and a dividing means for dividing the cathode ray tube into corners of the cathode ray tube supported by the supporting means. A groove forming means for forming a groove; heating a substantially central portion of the periphery of the side surface of the cathode ray tube for a predetermined time to apply thermal distortion to the substantially central portion; and heat the entire circumferential direction around the side surface of the cathode ray tube. A heating means for applying thermal strain to the entire circumferential direction around the side surface of the cathode ray tube. 2. An apparatus according to claim 1, wherein said supporting means includes a rotating means for rotating said cathode ray tube. 3. The groove forming means includes a rotary cutter.
2. A cathode ray tube splitting device according to claim 1, wherein said groove forming means forms a groove over the entire circumferential direction around the side surface of the cathode ray tube. 4. The cathode ray tube splitting device according to claim 1, wherein the heating means includes a heater wire for applying heat to the periphery of the side surface of the cathode ray tube. 5. An apparatus according to claim 1, wherein said support means includes positioning means for positioning said cathode ray tube. 6. A cathode ray tube dividing method for dividing a cathode ray tube into a panel portion and a funnel portion, wherein a dividing groove is formed at a corner of the cathode ray tube supported by a support means by a groove forming means. The heating means heats a portion including the substantially central portion of the periphery of the side surface of the cathode ray tube for a predetermined time to give thermal distortion to the substantially central portion, and heats the entire circumferential direction around the side surface of the cathode ray tube to form a cathode ray tube. A method for dividing a cathode ray tube, wherein thermal distortion is applied to the entire circumferential direction around the side surface of the tube. 7. The method according to claim 6, wherein the groove forming means forms a groove for division in the entire circumferential direction around the side surface of the cathode ray tube including a corner. 8. The heating means heats a substantially central portion of the periphery of the side surface of the cathode ray tube for a predetermined time to apply thermal distortion to the substantially central portion, and gradually increases the length of the heating means in contact with the periphery of the side surface of the cathode ray tube. 7. The method for dividing a cathode ray tube according to claim 6, wherein the entire length in the circumferential direction around the side surface of the cathode ray tube is heated to apply thermal strain to the entire circumferential direction around the side surface of the cathode ray tube. 9. A heating means heats a substantially central portion of the periphery of the side surface of the cathode ray tube for a predetermined time to give thermal distortion to the substantially central portion, and heats the entire circumferential direction of the periphery of the side surface of the cathode ray tube for a predetermined time. 7. The method for dividing a cathode ray tube according to claim 6, wherein thermal strain is applied to the entire circumferential direction around the side surface of the cathode ray tube.