JP3045058B2 - Exhaust pipe sealing device - Google Patents

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 process of manufacturing an electron tube such as a cathode ray tube, there is a step of heating and melting and sealing an exhaust pipe protruding from the tip of a neck of the electron tube, and cutting the exhaust pipe at the sealed portion. . In order 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 FIG. 1 has an electric heater 4 surrounding the vicinity of the base of an exhaust pipe 3 protruding from the tip of a neck portion 2 of a glass electron tube 1 and insulates heat emitted from the electric heater 4. The apparatus includes an oven 5 having a through hole that surrounds and into which an exhaust pipe can be inserted, and a vacuum device 6 that accommodates the open end of the exhaust pipe 3 and exhausts the exhaust gas with a vacuum pump (not shown). The electric heater 4 is formed by winding a nichrome wire as a heating element in a coil shape as shown in FIG.

Next, a method of heating and melting the exhaust pipe 3 will be described. The electron tube 1 is placed in a vertical position with the neck 2 down, and the exhaust pipe 3 is inserted into a through hole surrounding the electric heater 4 in the oven 5. A portion m to be sealed near the base of the exhaust pipe 3 is surrounded by the electric heater 4, and the tip of the exhaust pipe 3 is disposed 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 is reached, the electric heater 4 is energized. When the electric heater 4 generates heat, the portion m of the exhaust pipe 3 to be sealed is heated by radiant heat from the electric heater 4, and the portion m of the exhaust pipe 3 to be sealed is softened and melted. Since the inside of the exhaust pipe 3 is evacuated to a negative pressure, the glass of the portion m to be sealed is compressed at atmospheric pressure and sealed.

[0004]

Since the electric heater 4 for heating and melting the exhaust pipe 3 is formed by winding a nichrome wire in a coil shape as shown in FIG. 6, the length l of the heating element is long. The exhaust pipe 3 to be inserted has to be lengthened accordingly. There is a problem that the cost is increased because the exhaust pipe 3 is long, and that the exhaust resistance is increased and the exhaust time is lengthened. Further, if the heating element is long, it is difficult to uniformly heat the entire portion m to be sealed, and there is a problem that the sealing shape varies. The present invention has been proposed in view of such a situation, and an object of the present invention is to provide an exhaust pipe sealing device in which an exhaust pipe can be shortened by improving an oven and an electric heater, and a sealing shape is stable.

[0005]

In order to achieve the above object, an exhaust pipe sealing device 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. The present invention also provides an exhaust pipe sealing device in which the electric heater is disposed on the same plane substantially orthogonal to the exhaust pipe. Further, the present invention provides an exhaust pipe sealing device in which the shape of the inner wall of the oven is a spheroid about a short axis. Further, the present invention provides an exhaust pipe sealing device in which a coating reflecting heat is applied to an inner wall of the oven. Further, the present invention provides an exhaust pipe sealing device in which the electric heater is disposed at two focal points of the spheroid. In addition, the present invention provides an exhaust pipe sealing device in which the electric heater includes windings of a plurality of turns, and the width formed by each turn is gradually reduced from the outer circumference.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An exhaust pipe sealing device according to the present invention
This will be described with reference to FIGS. However, the same parts as those in the related art are denoted by the same reference numerals, and description thereof will be omitted. FIG. 1 is a longitudinal sectional view of an oven and an electric heater section of an exhaust pipe sealing device according to one embodiment of the present invention, and FIG. 2 is a transverse sectional view of them. The electric heater 40 of the present invention is shown in FIG.
As shown in FIG. 2, the electric heater 40 is formed in a spiral shape with a nichrome wire or the like so as to surround the exhaust pipe 3 in the same plane.
40b. The electric heater 40 according to the present invention is characterized in that the thickness of the exhaust pipe 3 in the axial direction is small. In this embodiment, the electric heater 40 is a single spiral. However, the electric heater 40 may be wound twice, three times or more as long as the thickness permits.

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 n to be sealed can be narrowed, so that the height of the oven 50 can be reduced. The length of the exhaust pipe 3 protruding from the end of the exhaust pipe 3 can be reduced. The electric heater 40
Is made of a heat insulating material such as ceramics, so that the heat released by the electric heater 40 can be effectively radiated to the portion to be sealed n of the exhaust pipe 3 without escaping to the outside.

As a more specific example, as shown in FIG. 3, for example, as shown in FIG. 3, a heat reflection coating 60 is applied to an inner wall 51a of an oven 51, so that heat emitted from the electric heater 41 can be efficiently discharged. , And can be concentratedly heated as indicated by an arrow in the figure by reflecting the light on a portion n to be sealed. In particular, by forming the inner wall 51a of the oven 51 into a spheroidal shape with the short axis as the axis, and disposing the outermost electric heater in the two focal points F and F of the spheroid, the electric heater 51 Heat of the oven 5 as shown by the arrow in the figure
The light is reflected by the heat reflection coating 60 of FIG. The degree of concentration can be set based on the elliptical minor axis and major axis and the eccentricity thereof, and the desired width of the portion n to be sealed of the exhaust pipe 3 can be melted.

In another embodiment, as shown in FIG. 4, the shape of the electric heater 42 is a plurality of turns, and the width of each turn is gradually reduced from the outer periphery. Thus, it is possible to directly reach the portion to be sealed n of the exhaust pipe 3 as shown by the arrow in the figure without interrupting the heat radiated by. The electric heater 4
In the fabrication of No. 2, the heater material having the same cross-sectional area is thinly rolled toward the outside so that the heat generation distribution is uniform, and the electric heater 42 is partially prevented from being deteriorated in the oven 52. I do.

Note that the electric heater is not a coiled nichrome wire or the like described in the above embodiment, but is obtained by forming an electric heating member on a substrate by plating or the like and then etching to obtain a flat 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 heat released can be reduced to a narrow range of the exhaust pipe. Can be. Further, the length of the exhaust pipe can be shortened and the exhaust resistance can be reduced, so that the exhaust time can 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 according to an embodiment of the present invention.

FIG. 2 is a transverse sectional view taken along line AA of FIG.

FIG. 3 is a longitudinal sectional view showing a heat radiation state by an oven and an electric heater according to different embodiments of the present invention.

FIG. 4 is a longitudinal sectional view of an oven and an electric heater according to different embodiments of the present invention.

FIG. 5 is a partial cross-sectional front view showing a state where the 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 Electric heater 40a, 40b Terminal of electric heater 50,51,52 Oven 51a Oven inner wall 60 Heat reflection coating n Sealing scheduled part

Claims (5)

(57) [Claims] 1. An exhaust pipe sealing device 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 the same as being substantially perpendicular 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 reflection 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 about a short axis. 4. The exhaust pipe sealing device according to claim 3, wherein said electric heater is disposed in two focal points of said spheroid. 5. The exhaust pipe sealing device according to claim 1, wherein said electric heater comprises a plurality of turns of windings, and the width formed by each turn is made smaller stepwise than the outer circumference.