JP3131468B2 - Manufacturing method of stem for electron tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron tube stem used for an electron tube such as a cathode ray tube, and more particularly to a stem for an electron tube having an exhaust pipe and a plurality of leads arranged at irregular intervals on the same circumference. The present invention relates to a method for manufacturing an electron tube stem.

[0002]

2. Description of the Related Art Generally, an electron tube such as a cathode ray tube has a structure as shown in FIG.
As shown in FIG. 1, a flare portion 2 is formed at one end of an exhaust pipe 1, and a plurality of lead wires 3 are formed on the same circumference of the flare portion 2.
Is used. The arrangement intervals of the plurality of lead wires 3 are not constant, and there are places where the intervals are wide.

Conventionally, this stem has been manufactured by an apparatus in which a plurality of a pair of stem forming dies are arranged at equal intervals on a peripheral portion of a rotary table which is driven to rotate intermittently.
As shown in (a), an exhaust pipe 1, a plurality of lead wires 3 and a ring-shaped glass member for forming a flare portion 2 are arranged in a lower mold 5a, and these members are heated by a burner. After softening one end of the exhaust pipe 1 and the ring-shaped glass member 6, the upper mold 5b is lowered and pressure-formed by the pair of molds 5a and 5b as shown in FIG.
Press process). Then, the upper mold 5b is raised and heated again by a burner to soften one end of the exhaust pipe 1 and the formed flare portion 2, and then lower the upper mold 5b as shown in FIG. Press molding with a pair of molds 5a and 5b (second
Press process). Then, while raising the upper mold 5b,
It is manufactured by floating the formed swim from the lower mold 5a, and removing deburring generated at the time of molding by heating and finishing.

In the above-described manufacturing method, a case has been described in which the members arranged on the lower mold 5a are repeatedly heated and softened twice and pressure forming is repeated twice to manufacture a stem. Before or after the first pressing step, pre-processing is performed to forcibly bring the heat-softened ring-shaped glass member into close contact with the lead wire using a roller, and then heat softening and pressure molding are performed. There is a method of manufacturing repeatedly.

[0005] In any of these manufacturing methods, the heating performed during the press molding is performed while the formed flare portion is kept floating by about several mm from the lower mold.
This is to ensure that the temperature of the part that has fallen due to contact with the mold during molding, especially the lower part of the flared part, is set to a temperature suitable for pressure molding so that heating will not be insufficient for the next pressure molding. To do that.

However, the above manufacturing method has the following problems.

More specifically, after the first press forming (first press step), the flare portion is lifted from the lower mold and heated by a burner. As shown in FIG. Tends to hang down, and particularly, as shown in FIG. 2B, the hang-down at the portion 8 where the interval between the lead wires 3 is wide increases. Also, the more the puddle is formed at the joint between the one end of the exhaust pipe 1 and the flare section, the more easily it sags. In particular, when the ring-shaped glass member heated and softened by the preliminary processing using the roller is forcibly brought into close contact with the lead wire, the tendency becomes stronger as the amount of pushing between the lead wires is larger. In addition, since the heat-softened glass easily flows into the central portion of the portion where the lead wires 3 are wide, the portion where the distance between the lead wires 3 is wide is more likely to hang down than other portions.

The flare portion 2 softened by heating as described above
Of the glass 7 hangs down before the next pressing, the sagged glass comes into contact with the lower mold 5a, and the temperature of the glass at the contact portion decreases. In particular, cracks are likely to occur on the surface near the joint between the exhaust pipe 1 and the flare portion 2, which causes cracks.

As shown in FIG. 6, when the upper mold 5b is eccentric with respect to the lower mold 5a at the time of the first pressure molding, the glass between the lower mold 5a and the upper mold 5b becomes large. Flow into the joint portion between the one end portion of the exhaust pipe 1 and the flare portion 2 so as to be easily accumulated. In this case, when the wide portion between the lower die 5a and the upper die 5b coincides with the wide portion between the lead wires 3, the droop of the glass becomes large, and the resulting stress tends to cause forming cracks. .

[0010]

As described above, the flare portion is formed at one end of the exhaust pipe, and a plurality of lead wires hermetically pass through the same circumference of the flare portion at irregular intervals. For the pipe stem, a pair of upper and lower stem forming dies is used, and an exhaust pipe, a plurality of lead wires and a ring-shaped glass member for forming a flare portion are arranged in the lower die, and at least two times with respect to these members. It is manufactured by repeating heating softening and pressure molding, and heating the molded flared part while floating from the lower mold.

As a result, the glass in the flare portion softened by heating hangs down, especially in a portion where the lead wire interval is wide, so that the hanged glass comes into contact with the lower mold, and as a result of the resulting stress, molding breakage occurs. May be caused. Also, if the upper mold is eccentric with respect to the lower mold at the time of the first pressure molding, the glass flows into the portion where the space between the lower mold and the upper mold is widened, and the one end of the exhaust pipe and the flare portion are connected. When the gap between the lower mold and the upper mold is larger than the gap between the lead wires, the sagging of the glass increases, and the resulting stress also increases because the sump can easily accumulate at the joint. Therefore, molding cracks are likely to occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is intended to prevent the softened glass from dripping on a lead wire having unequal intervals, which occurs in a wide portion of the lead wire. It is another object of the present invention to provide a manufacturing method for reducing molding cracks caused by the sag.

[0013]

Means for Solving the Problems A ring-shaped glass member, an exhaust pipe and a plurality of lead wires are arranged on one of a pair of stem forming dies and heated, and the heating causes the glass member and one end of the exhaust pipe to be heated. Is softened and then press-molded by a pair of stem molds, and this heat-softening and press-molding are repeated at least twice to form a flared portion at one end of the exhaust pipe, and the same circumference of the flared portion is formed. In a method of manufacturing a stem for an electron tube in which a plurality of lead wires penetrate at unequal intervals, in a method of forming a stem for an electron tube, at least two times of press forming are performed at the time of press forming other than the final press forming. Molded using a mold in which the protrusion for molding the inner surface shape of the connection between the exhaust pipe and the flare provided on the other mold of the stem molding die is eccentric to the side where the interval between the multiple lead wires is wide I did it.

[0014]

As described above, during the pressure molding other than the final pressure molding among the pressure molding repeated at least twice, the exhaust pipe provided on the other of the pair of stem molding dies and the flare are formed. When the protrusion for forming the inner shape of the connection portion is eccentric to the side of the portion where the interval between the plurality of leads is wide, the thickness of the portion where the interval between the leads is wide can be made thinner than the thickness of the other portions. This makes it possible to prevent the sagging of the heat-softened glass from becoming large at a wide interval between the lead wires, and to prevent molding cracks caused by the large sag at the wide interval between the lead wires.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings based on embodiments.

As shown in FIG. 2, a plurality of (seven in the illustrated example) stem forming dies 11 are arranged at equal intervals around the periphery of a turntable 10 which is intermittently driven to rotate by a driving device. Manufactured by equipment. The manufactured stem is
A flare portion 2 is formed at one end of the exhaust pipe 1 shown in FIG. 3, and a plurality of lead wires 3 are formed on the same circumference of the flare portion 2.
Are stems arranged at predetermined unequal intervals.

First, as shown in FIG. 1A, an exhaust pipe 1, a plurality of lead wires 3, and a ring-shaped glass member 13 for forming a flare portion are arranged on a lower mold 12a located on the loading stage. Then, in the next heating stage, each member arranged in the lower mold 12a is preheated by a burner, and in the next molding stage, each preheated member is further heated by a burner. After the portion and the ring-shaped glass member 13 have been sufficiently heated and softened, as shown in FIG. 1B, the upper mold 12b is lowered and pressure-formed by a pair of upper and lower molds 12a and 12b (first press). Process).

In this first pressure molding, the eccentricity S
As shown in FIG. 1, the protrusion 14 for forming the inner surface shape of the connection between the one end of the exhaust pipe 1 of the upper die 12b and the flare portion 2 is eccentric to the side of the lead wire 3 where the space between the leads 3 is large. Is used. The amount of eccentricity S1 is limited by the clearance between the lower mold 12a and the exhaust pipe 1.
Eccentricity of about 2 mm is possible.

Next, the upper mold 12b is once raised, and the molded stem is floated from the stem molded from the lower mold 12a. Each member cooled by the above pressure molding is heated again by a burner. As shown in FIG.
b is lowered, and pressure-formed by a pair of upper and lower dies 12a and 12b (second press step).

In the pressure forming in the second pressing step, as shown by the eccentricity S2 in the figure, the projection 14 of the upper die 12b is eccentric in the direction opposite to the eccentric direction in the first pressing step. The upper mold 12b is used.

After the second pressing step, the formed stem is lifted from the lower mold 12a and heated by a burner to remove burrs generated by the forming and to perform finishing. By the way, as described above, at the time of the first pressure molding, the projection 14 for molding the inner surface shape of the connection portion between the one end of the exhaust pipe 1 and the flare portion 2 is eccentric to the side where the space between the lead wires 3 is wide. When the upper die 12b is used for molding, the space between the upper and lower dies 12a and 12b at the wide portion of the lead wire 3 is reduced, and the thickness at the wide portion is reduced by the thickness of the other narrow portions. This makes it possible to suppress softening and drooling of the softened glass in the portion where the interval between the lead wires 3 is large at the time of the next heating. Therefore, in the next second pressing step, the molding is performed by using the upper mold 12b which is eccentric in the direction opposite to the direction at the time of the first pressure molding.
Cooling and solidification of the glass due to local contact with the lower mold 12a due to the local accumulation or drooping of the lower mold 12b is prevented, and the connection between one end of the exhaust pipe 1 and the flare section 2, especially the lead wire 3 The pressing force applied to the portion having a wide interval is reduced, and the flow of the glass is reduced, so that molding cracks which have conventionally occurred on the stem surface can be reduced.

In the above embodiment, the protrusion of the upper die in the final pressure forming (second press step) is eccentric in the direction opposite to the eccentric direction of the protrusion in the first press step. ,
In this final pressure molding, pressure molding may be performed using an upper mold that does not decenter the protrusion, and the same effect as in the above embodiment can be obtained.

Further, in the above embodiment, the case where the stem is formed by two times of press forming including the first and second pressing steps has been described. However, when the stem is formed by three times of press forming, In the first pressure molding (first pressing step), as in the above-described embodiment, an upper mold whose projection is eccentric to the side where the lead wire is wide is used, and the final pressure molding (in this case, the third pressing step) is performed. For the pressing step), use an upper mold that is eccentric in the opposite direction to the first pressure molding or a coaxial upper mold that does not have eccentricity, and performs intermediate pressing (in this case, the second pressing step) with the first pressing. 1,
The same effect can be obtained by using the upper die located in the middle of the position of the protrusion in the third pressing step.

Further, when the stem is formed by three or more pressure moldings, the pressure molding from the first pressure molding to one stage before the final pressure molding is performed on the side of the portion where the lead wire interval is wide. The same effect can be obtained by using an upper mold with an eccentric projection, and using an upper mold with eccentricity in the opposite direction or a coaxial upper mold without eccentricity in the final pressing.

[0025]

According to the present invention, a ring-shaped glass member, an exhaust pipe and a plurality of lead wires are arranged in one of a pair of stem forming dies and heated, and this heating softens the glass member and one end of the exhaust pipe. Thereafter, pressure molding is performed by a pair of stem molding dies, and the heating softening and the pressure molding are repeated at least twice, and a flare portion is connected and formed to one end of the exhaust pipe,
In the method of manufacturing a stem for an electron tube, in which a plurality of lead wires penetrate the same circumference of the flare portion at unequal intervals, a method other than the final pressure forming is performed at least twice in the pressure forming. When molding using a mold in which the projections of the other mold used during pressure molding are eccentric to the side of the part where the distance between the plurality of lead wires is wide, the thickness of the part where the distance between the lead wires is wide is the same as that of the other part. It can be thinner than the wall thickness, and it can prevent heat accumulation and drooping at the wide part of the lead wire of the heat-softened glass from becoming large. Mold cracking caused by sagging can be prevented, and the production yield of the stem and the operating rate of the stem production device can be improved. In addition, molding cracks that cannot be detected by the appearance inspection do not flow into the electron tube manufacturing process to cause defects, thereby reducing quality accidents of the electron tube and improving reliability.

[Brief description of the drawings]

FIGS. 1A to 1C are views for explaining a method of manufacturing an electron tube stem according to an embodiment of the present invention.

FIG. 2 is a view for explaining the manufacturing process.

FIG. 3A is a front view partially showing a cross section of a configuration of an electron tube stem, and FIG. 3B is a plan view thereof.

FIGS. 4A to 4C are views for explaining a conventional method of manufacturing a stem for an electron tube.

FIGS. 5A and 5B are diagrams for explaining problems in a conventional method for manufacturing a stem for an electron tube.

FIG. 6 is a diagram for explaining a problem that occurs when an upper mold for press-molding a stem is eccentric with respect to a lower mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Exhaust pipe 2 ... Flare part 3 ... Lead wire 11 ... Stem molding die 12a ... Lower die 12b ... Upper die 13 ... Ring-shaped glass member 14 ... Projection

Claims (1)

(57) [Claims] 1. A ring-shaped glass member, an exhaust pipe and a plurality of lead wires are arranged and heated on one of a pair of stem forming dies, and this heating softens one end of the glass member and the exhaust pipe. Thereafter, pressure molding is performed by the pair of stem molding dies, and the heating softening and the pressure molding are repeated at least twice, so that a flare portion is connected to one end of the exhaust pipe, and the flare portion has the same circle. A method of manufacturing a stem for an electron tube in which a plurality of lead wires are formed at irregular intervals through a stem, wherein the pressure forming other than the final pressure forming among the pressure forming repeated at least twice. At times, a protrusion for forming an inner surface shape of a connection portion between the exhaust pipe and the flare provided on the other of the pair of stem forming dies was eccentric to a side where a space between the plurality of lead wires was large. Using a mold Method for manufacturing a stem for an electron tube, characterized by molding.