JPH09147748A - Exhaust pipe sealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To thin an electric heater surrounding a portion neat the root of an exhaust pipe, so as to shorten the portion to be sealed of the exhaust pipe, to reduce exhaust resistance, and to reduce exhaust time by forming the electric heater within the same plane that is approximately perpendicular to the exhaust pipe inside an oven. SOLUTION: This exhaust pipe sealing device heats the center of the exhaust pipe 3 of an electron tube using a spiral electric heater 41 surrounding the center within the same plane and an oven 51 surrounding the heater 41. The interior wall 51a of the oven 51 is in the form of an ellipsoid of revolution with a minor axis as its axis of revolution, and the heater 41 on the outermost periphery is placed within the two foci F, F of the ellipsoid of revolution, with a heatreflecting coating 60 applied to the interior wall 51a. Therefore, heat from the heater 41 is reflected by the coating 60 as shown by the arrow, to efficiently melt the portion (n) to be sealed of the exhaust pipe 3 by the desired width. Thus the portion (n) can be shortened by thinning of the heater 51, exhaust resistance can be made smaller, and exhaust time can be reduced, resulting in a stably sealed configuration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust pipe sealing device suitable for sealing an exhaust pipe of an electron tube such as a cathode ray tube.

[0002]

2. Description of the Related Art In a manufacturing process of an electron tube such as a cathode ray tube, there is a step of heating and melting an exhaust pipe protruding from a tip of a neck of the electron tube to seal the exhaust pipe and cutting the exhaust pipe at the sealed portion. . To heat and melt the exhaust pipe, an exhaust pipe sealing device as shown in FIG. 5 is used. The exhaust pipe sealing device shown in the same figure insulates the heat emitted from the electric heater 4 surrounding the base of the exhaust pipe 3 protruding from the tip of the neck portion 2 of the electron tube 1 made of glass and the heat emitted from the electric heater 4. The oven 5 is provided with a through hole that surrounds the exhaust pipe 3 and a vacuum device 6 that accommodates the open end of the exhaust pipe 3 and evacuates it with a vacuum pump (not shown). As shown in FIG. 6, the electric heater 4 is formed by winding a nichrome wire which is a heating element in a coil shape.

Next, a method of heating and melting the exhaust pipe 3 will be described. The electron tube 1 is placed in a vertical posture with the neck portion 2 down, and the exhaust tube 3 is inserted into a through hole that surrounds the electric heater 4 in the oven 5. A planned sealing portion m near the root of the exhaust pipe 3 is surrounded by the electric heater 4, and the tip of the exhaust pipe 3 is arranged in the vacuum device 6. The inside of the electron tube 1 and the exhaust tube 3 is evacuated by the vacuum device 6, and when the vacuum state is reached, the electric heater 4 is energized. When the electric heater 4 generates heat, the planned sealing portion m of the exhaust pipe 3 is heated by the radiant heat from the electric heater 4, and the planned sealing portion m of the exhaust pipe 3 is softened and melted. Since the inside of the exhaust pipe 3 is evacuated to a negative pressure, the glass of the sealing target portion m is compressed at the atmospheric pressure and sealed.

[0004]

Since the electric heater 4 for heating and melting the exhaust pipe 3 is made by winding a nichrome wire in a coil shape as shown in FIG. 6, the length l of the heating element is long. It was also necessary to lengthen the exhaust pipe 3 to be inserted accordingly. Since the exhaust pipe 3 is long, there are problems that the cost is high and that the exhaust resistance is large and the exhaust time is long. Further, if the heating element is long, it is difficult to uniformly heat the entire planned sealing portion m, and the sealing shape varies. The present invention has been proposed in view of such circumstances, and an object of the present invention is to provide an exhaust pipe sealing device capable of shortening the exhaust pipe and stabilizing the sealing shape by improving the oven and the electric heater.

[0005]

In order to achieve the above object, in an exhaust pipe sealing apparatus for heating an exhaust pipe by an electric heater surrounding a central portion of the exhaust pipe for an electron tube and an oven surrounding the heater. Provided is an exhaust pipe sealing device in which the electric heater is arranged in the same plane substantially orthogonal to the exhaust pipe. Also provided is an exhaust pipe sealing device in which the shape of the inner wall of the oven is a spheroid with the minor axis as an axis. Also provided is an exhaust pipe sealing device in which a coating for reflecting heat is applied to the inner wall of the oven. Further, there is provided an exhaust pipe sealing device in which the electric heater is arranged at two focal points of the spheroid. Also provided is an exhaust pipe sealing device in which the electric heater comprises a winding of a plurality of turns, and the width formed by each turn is gradually reduced from the outer circumference.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION An exhaust pipe sealing device according to the present invention,
This will be described with reference to FIGS. 1 and 2. However, the same parts as those of the related art are designated by the same reference numerals and the description thereof will be omitted. FIG. 1 is a vertical sectional view of an oven and an electric heater portion of an exhaust pipe sealing device according to an embodiment of the present invention, and FIG. 2 is a transverse sectional view thereof. The electric heater 40 of the present invention is shown in FIG.
As shown in FIG. 2, a nichrome wire or the like is formed in a spiral shape so as to surround the exhaust pipe 3 in the same plane, and both ends of the nichrome wire of the electric heater 40 have terminals 40a for energization,
40b. The electric heater 40 according to the present invention is characterized in that the exhaust pipe 3 has a small axial thickness. Although the electric heater 40 is a single spiral in the present embodiment, it may be wound in double, triple or more layers as long as the thickness allows.

Since the thickness of the electric heater 40 according to the present invention is thin, the range in which the exhaust pipe 3 is melted is narrow, and the width of the portion to be sealed n can be narrowed. Therefore, the height of the oven 50 can be reduced, so that the neck portion 2 of the electron tube 1 can be reduced. It is possible to shorten the length of the exhaust pipe 3 protruding from the tip of the. The electric heater 40
The oven 50 surrounding the heater is made of a heat insulating material such as ceramics so that the heat released by the electric heater 40 can be effectively applied to the sealing target portion n of the exhaust pipe 3 without being released to the outside.

As a more specific example, as shown in FIG. 3, for example, the inner wall 51a of the oven 51 is provided with a heat-reflecting coating 60 so that the heat released from the electric heater 41 can be efficiently discharged from the exhaust pipe 3. It is possible to perform centralized heating as indicated by an arrow in the drawing by reflecting the light on the portion n to be sealed. In particular, by forming the inner wall 51a of the oven 51 into a spheroidal shape with the minor axis as an axis and disposing the outermost electric heater in the two focal points F of the spheroid, the electric heater 51 The heat of the inside wall 5 of the oven
It can be reflected by the heat reflection coating 60 of 1a and concentrated on the exhaust pipe 3. The degree of concentration can be set based on the minor axis and major axis of the elliptical shape and the eccentricity resulting therefrom, and the desired width of the planned sealing portion n of the exhaust pipe 3 can be melted.

As another embodiment, as shown in FIG. 4, the electric heater 42 is formed into a winding having a plurality of turns, and the width formed by each turn is gradually reduced from the outer circumference. In this configuration, the heat radiated by the exhaust gas can be directly reached to the planned sealing portion n of the exhaust pipe 3 as indicated by an arrow in the figure without being blocked. In addition, this electric heater 4
In manufacturing No. 2, a heater material having the same cross-sectional area is rolled thinly toward the outside so that the heat generation distribution is made uniform so that the electric heater 42 is not partially deteriorated in the oven 52. To do.

The electrothermal heater is not the coil-shaped nichrome wire described in the above embodiment, but an electrothermal member is formed on the substrate by plating or the like and then etched to obtain a flat and spiral heating element. May be used.

[0011]

According to the present invention, the thickness of the electric heater for heating the exhaust pipe can be reduced, and the released heat can be narrowed to a narrow range of the exhaust pipe, so that the planned sealing portion of the exhaust pipe is shortened. You can Further, since the length of the exhaust pipe can be shortened and the exhaust resistance can be reduced, the exhaust time can also be shortened. Further, since the heating portion is short, the sealing portion is constant and a stable sealing shape can be obtained.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of an oven and an electric heater part according to an embodiment of the present invention.

2 is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is a vertical cross-sectional view showing a state of heat radiation by an oven and an electric heater according to another embodiment of the present invention.

FIG. 4 is a vertical sectional view of an oven and an electric heater according to another embodiment of the present invention.

FIG. 5 is a partially sectional front view showing a state where an exhaust pipe is heated by a conventional exhaust pipe sealing device.

FIG. 6 is a perspective view of a conventional electric heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron tube 2 Neck part 3 Exhaust pipe 40,41,42 Electrothermal heater 40a, 40b Electrothermal heater terminal 50,51,52 Oven 51a Oven inner wall 60 Heat reflection coating n Sealing scheduled part

Claims (5)

[Claims] 1. An exhaust pipe sealing apparatus for heating an exhaust pipe by an electric heater surrounding a central portion of an exhaust pipe for an electron tube and an oven surrounding the heater, wherein the electric heater is substantially orthogonal to the exhaust pipe. An exhaust pipe sealing device, which is arranged in a plane. 2. The exhaust pipe sealing device according to claim 1, wherein a heat-reflecting coating is applied to an inner wall of the oven. 3. The exhaust pipe sealing device according to claim 2, wherein the shape of the inner wall of the oven is a spheroid having a minor axis as an axis. 4. The exhaust pipe sealing device according to claim 3, wherein the electrothermal heater is arranged in two focal points of the spheroid. 5. The exhaust pipe sealing device according to claim 1, wherein the electrothermal heater comprises a winding having a plurality of turns, and the width formed by each turn is gradually reduced from the outer circumference.