JPH0498741A - Explosion-proof method for cathode-ray tube - Google Patents

Abstract

PURPOSE:To obtain a stable clamping force for a cathode-ray tube while keeping the shape of a clamping metal annular body in line with the maximum diameter section of a cathode-ray tube envelope by applying the metal annular body after the predetermined amount of plastic deformation through an expansion process. CONSTITUTION:The maximum diameter external section of a cathode-ray tube is clamped via a shrinkage fitting process. When the external side of a metal annular body is elongated by 0.15 to 0.3% and plastically deformed via an expansion process, the metal annular body comes to have approximately constant stress in a plastic zone. As a result, a less dispersed and stable clamping force can be obtained by accurately controlling a difference between the external length of the maximum diameter section of the cathode-ray tube and the internal length of the metal annular body, so as to keep the stress of the metal annular body due to cold shrinkage after heated expansion within the plastic zone, Concurrently, a stable and proper explosion-proof treatment can be applied to the cathode-ray tube.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention (Industrial Application Field) The present invention relates to a method for explosion-proofing a cathode-ray tube, and particularly to a method for protecting a cathode-ray tube by a shrink-fitting method.

(Prior Art) In general, a cathode ray tube such as a color picture tube has a maximum diameter on the side of the phosphor screen (1) that displays an image, and a funnel-shaped cone in this maximum diameter, as shown in FIG. (2) is joined or welded to form a glass envelope (3). Since the inside of this envelope (3) is evacuated to a high vacuum, it may implode due to atmospheric pressure applied from the outside. In order to prevent this implosion, it is known that an explosion-proof means such as a metal ring (4) is provided on the outer periphery of the maximum diameter portion of the envelope (3).

Conventionally, there are various methods for this explosion-proofing method, but one method is to wrap tape (6) around the maximum diameter of the cathode ray tube envelope (3), while wrapping a tape (6) around the maximum diameter of the cathode ray tube envelope (3). After forming a metal ring (4) with a short inner circumferential length and heating and expanding this metal ring (4), the maximum diameter part of the cathode ray tube is inserted inside the metal ring (4), and then it is cooled to achieve the maximum diameter as described above. There is an explosion-proof method called a shrink-fitting method in which a metal ring (4) is attached to the outer periphery of the diameter portion.

This explosion-proofing method using the shrink fitting method utilizes the tightening force generated by cooling contraction after heating expansion of a metal ring whose inner circumference is shorter than the outer circumference of the maximum diameter of the envelope (3).
It is extremely important to keep the relationship between the outer circumference of the maximum diameter part of the envelope (3) and the inner circumference of the metal ring body constant, especially the difference between them.

By the way, as shown in FIG. 5(a), the metal ring body is usually made of a long strip made of mild steel or the like with a predetermined length (7
), and as shown in (b), the strip (7) is formed into an annular body (8), and then as shown in (C),
The two ends are butted together and patch welded using a patch plate (9) to form a substantially rectangular metal ring (4), and as shown in (d), cathode ray tubes are attached to the four corners of the metal ring (4). It is formed by welding a lug plate (10) for attaching it to the cabinet. Therefore, the inner circumferential length of the metal ring (4) to be formed is determined by the cutting error when cutting a long strip, and when the cut strip (7) is formed into an annular shape and then patch welded. It has an error that is an addition of errors.

On the other hand, the face plate (panel in color picture tubes) that constitutes the largest diameter part of the cathode ray tube's envelope (3) is molded using a glass mold, so the manufacturing process takes into account errors in the mold. There is some variation above.

Therefore, even if the metal ring (4) with the error is combined with the cathode ray tube envelope (3), the difference between the outer circumference of the maximum diameter part of the cathode ray tube and the inner circumference of the metal ring is , not constant,
As a result, a predetermined tightening force may not be obtained. In some cases, if the direction of the error, that is, the inner circumference of the metal ring (4) is longer than the specified length, and the outer circumference of the maximum diameter part of the polar ray tube envelope (3) is shorter than the specified length, In some cases, it may not be possible to apply the tightening force due to cooling contraction.

In addition, there is a method of correcting the inner circumference of the metal ring according to the outer circumference of the maximum diameter part of the cathode ray tube envelope. When the two ends of the strip are butted together and the two ends are patch welded using a joint plate, this is done by changing the distance between the two ends, so such a metal ring can be used to This does not match the shape of the diameter portion, and as a result, the tightening force due to cooling contraction of the metal ring becomes uneven on each side of the maximum diameter portion of the cathode ray tube envelope, making it impossible to expect stable explosion-proof treatment.

(Problem to be Solved by the Invention) As described above, one method of explosion-proofing a cathode ray tube is to form in advance a metal ring whose inner circumference is slightly shorter than the outer circumference of the maximum diameter of the cathode ray tube's envelope. There is a shrink-fitting method in which the metal ring is heated and expanded, the largest diameter part of the cathode ray tube is inserted inside the metal ring, and then the metal ring is cooled and the metal ring is attached to the outer periphery of the largest diameter part. This shrink-fitting method utilizes the tightening force generated by cooling contraction after heating expansion of a metal ring whose inner circumference is shorter than the outer circumference of the maximum diameter of the envelope. It is extremely important to keep the relationship between the outer circumference and the inner circumference of the metal ring body constant, especially the difference between them.

However, the metal rings actually used are subject to cutting errors when cutting long strips into strips of a predetermined length, and the cut strips are formed into a ring shape and then patch welded. There is an error due to the addition of time error, etc. On the other hand, outside the cathode ray tube @J
Since there are manufacturing errors in the face plate that constitutes the maximum diameter of the tube, the difference between the outer circumference of the cathode ray tube's largest diameter and the inner circumference of the metal ring is constant. As a result, the specified tightening force may not be obtained. In some cases, depending on the direction of the error, it may not be possible to apply a tightening force to the cathode ray tube due to cooling contraction after heating expansion. Also, is there a method to correct the inner circumference of the metal ring according to the outer circumference of the maximum diameter part of the cathode ray tube? Normally, the inner circumference of the metal ring is corrected by using a band plate formed in an annular shape. When the two ends are butted together and the two ends are patch welded using a patch plate, this is done by changing the distance between the two ends. As a result, the tightening force due to cooling shrinkage of the metal ring becomes uneven on each side of the maximum diameter part of the cathode ray tube envelope, and there is a problem that stable explosion-proof treatment cannot be expected.

This invention was made to solve the above problems, and even when the variation in the inner circumference of the metal ring is reduced and the inner circumference is corrected, the maximum diameter of the cathode ray tube envelope is reduced. An object of the present invention is to provide an explosion-proof method for cathode ray tubes that maintains a shape that conforms to the part and provides stable tightening force.

After heating and expanding a metal ring whose inner circumference is shorter than the outer circumference of the maximum diameter part of the cathode ray tube, the maximum diameter part of the cathode ray tube is inserted inside this metal ring, and the cathode rays are expanded by cooling and shrinking the metal ring. In an explosion-proof method for cathode ray tubes that tightens the maximum diameter part of the tube, after forming the metal ring, the entire circumference of the metal ring is stretched by 0.15 to 0.3% to plastically deform it. A plastically deformed metal ring is used to tighten the maximum diameter part of the cathode ray tube.

(Function) Metal materials generally used as metal rings for shrink-fitting methods have relatively clear elastic ranges, plastic ranges, and yield points.
In particular, regarding mild steel materials that are often used for metal rings,
As shown in the stress-strain curve in FIG. 3, there is a plastic region in which almost constant stress is generated regardless of the magnitude of strain. Therefore, after forming a metal ring, if the entire circumference of the metal ring is stretched by 0.15 to 0.3% by stretching and plastically deformed, it will have almost constant stress in the plastic region. As a result, the difference between the outer circumference of the maximum diameter part of the cathode ray tube and the inner circumference of the metal ring must be precisely controlled so that the stress in the metal ring caused by cooling contraction after heating expansion does not deviate from the plastic range. As a result, stable tightening force with little variation can be obtained. In addition, the yield point increases due to the aging effect of strain, and the stress in the plastic region increases, making it possible to perform stable and reliable explosion-proof treatment.

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

As shown in FIG. 1(a), a long strip made of mild steel is cut into strips (7) of a predetermined length, and as shown in FIG. 1(b), the cut strips ( 7) is formed into a substantially rectangular annular body (8) approximating the outer periphery of the maximum diameter part of the cathode ray tube envelope. Next, as shown in (C), the two ends are butted together and the two ends are seam welded using a seam plate (9) to form a rectangular metal ring body 20). Next, as shown in (d), 4 of this metal ring body (20)
A lug plate (10) for attaching the cathode ray tube to the cabinet is welded to the corner.

Furthermore, as shown in (e), an overhanging tool (21) divided into a plurality of pieces (four pieces in the illustrated example) is inserted inside the metal ring (20) to which the lug plate (lO) is welded. Then, by driving this stretching tool (21) in the radial direction shown by the arrow (22), plastic deformation is performed by stretching the entire circumference of the metal ring (20) by 0.15 to 0.3%. let

Thereafter, using this plastically deformed metal ring (23), the cathode ray tube is subjected to explosion-proof treatment. That is, first, tape is wrapped around the maximum diameter part of the cathode ray tube envelope. On the other hand, the plastically deformed metal ring (23) is heated and expanded, and the largest diameter portion of the cathode ray tube wrapped with tape is inserted inside the expanded metal ring (23). Thereafter, it is cooled and the outer periphery of the maximum diameter part of the cathode ray tube is tightened by cooling contraction.

By the way, if plastic deformation is caused in advance to stretch the entire circumference of the metal ring body (23) as described above, as shown in the stress-strain curve (25) in FIG. It has a clearly defined elastic region (26), plastic region (27), and yield point (28), and especially for mild steel materials, there is a plastic region that produces approximately constant stress regardless of the magnitude of strain (elongation). Therefore, by accurately controlling the difference between the outer circumferential length of the maximum diameter part of the cathode ray tube and the inner circumferential length of the metal ring (23), the cathode ray tube can be tightened with a substantially constant stress in the above-mentioned plastic region. . In addition, as shown by the curve (29) in comparison with the curve (25) in FIG. 4, the metal ring (23
), the yield point (28) increases due to the aging effect of strain, and the plastic region (2
The stress in step 7) is increased, and as a result, stable and reliable explosion-proof treatment can be performed.

In addition, the amount of extension of the inner peripheral length of the metal ring body (23) is 0.15~
The reason for setting it at 0.3% is that in mild steel, there is a yield point at a strain of about 0.1%28), so the amount of extension of the inner circumference is set to 0.
．． If it is less than 15, the stress after cooling and contraction of the heated and expanded metal ring (23) will result in an elastic region (26), which may make it impossible to obtain a predetermined tightening. Moreover, if the amount of elongation exceeds 0.3%, it approaches the breakage region (30) shown in FIG. 4, which makes it easy to break during cooling contraction after heating expansion or after completion of explosion-proofing treatment, and this is to avoid this.

In the above embodiment, after attaching the lug plate to the metal ring body, the metal ring body was plastically deformed by stretching process, but conversely, after the metal ring body was plastically deformed by stretching process, the lug plate was may be installed.

Further, in the above embodiment, the metal ring body (4) made of mild steel material
Although the case has been described, the present invention is also applicable to other metal materials such as carbon steel and stainless steel that can be used as a metal ring for shrink fitting. However, for metal materials other than mild steel, the stress increases slightly as the strain increases in the plastic region, so the difference between the outer circumference of the maximum diameter part of the cathode ray tube and the inner circumference of the metal ring (4) It is desirable to manage this with even more precision.

[Effects of the Invention] After heating and expanding a metal ring whose inner circumference is shorter than the outer circumference of the maximum diameter of the cathode ray tube, the maximum diameter of the cathode ray tube is inserted inside this metal ring, and the metal ring is expanded. In an explosion-proofing method for cathode ray tubes in which the largest diameter part is tightened by cooling shrinkage, after a metal ring is formed, the entire circumference of the metal ring is stretched by 0.15 to 0.3% by stretching to cause plastic deformation. Then, when this plastically deformed metal ring is used to tighten the largest diameter part of the cathode ray tube, the plastic deformation allows it to be tightened with almost constant stress in the plastic region, and as a result, after heating and expansion, By precisely controlling the difference between the outer circumference of the maximum diameter of the cathode ray tube and the inner circumference of the metal ring so that the stress in the metal ring caused by cooling contraction does not deviate from the plastic range, stable Provides tightening force. In addition, the yield point increases due to the aging effect of strain, and the stress in the plastic region increases, making it possible to perform stable and reliable explosion-proof treatment.

[Brief explanation of drawings]

Figures 1 to 3 are detailed explanatory diagrams of this invention.
Figures (a) to e) are diagrams for explaining the explosion-proof method, which is an example of the method, Figure 2 is a stress-strain curve diagram of a mild steel material, and Figure 3 is a diagram of a plastically deformed metal ring. Figure 1 is a diagram showing the structure of an explosion-proof cathode ray tube, and Figures 1 (a) to d) are diagrams for explaining the effects of conventional explosion-proofing methods. It is a diagram. 7... Band plate, 8... Annular body, 9... Joint plate, lO... Lug plate, 20.23... Metal ring body. Agent Patent Attorney Norihiro Ogo Figure 0.1 0.2 0.3 0.4 0.5 0.6 Wang (extension t7') ('/,) Figure i (extension) (0n)

Claims (1)

[Claims] A metal ring having an inner circumference shorter than the outer circumference of the maximum diameter part of the cathode ray tube is formed, and after this metal ring is heated and expanded, the maximum diameter of the cathode ray tube is placed inside the metal ring. In the method for explosion-proofing a cathode ray tube, in which a diameter portion is inserted and the maximum diameter portion of the cathode ray tube is tightened by cooling contraction of the metal ring, after the metal ring is formed, the entire circumference of the metal ring is stretched. 0.15 to 0.3% stretching and plastic deformation,
An explosion-proofing method for a cathode ray tube, comprising tightening the largest diameter part of the cathode ray tube using this plastically deformed metal ring.