JPH0423393B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method of manufacturing an airtight terminal, and more particularly to an improvement in a glass tablet used for glass-sealing a lead to a lead sealing hole in an outer ring metal in an airtight terminal for a refrigerator or the like. Prior Art The airtight terminal 1 for a refrigerator is shown in FIGS. 4 and 5, for example.
As shown in the figure, a lead sealing hole 3 is formed in the outer ring metal 2 by burring.
It has a structure in which the leads 4 are sealed with glass 5 and terminal plates 6, 6 are welded to both ends of the leads 4. This airtight terminal 1 is used to supply power to a motor enclosed in a high-pressure container of a compressor through which a heat medium flows back, and the glass sealing process is performed in the following steps. As shown in FIG. 6, the outer ring metal 2 is positioned and fixed to the sealing jig 7, and the leads 4 and glass tablet 8 are fitted into the lead sealing holes 3 of the outer ring metal. Here, the peripheral edge 2a of the opening on the top surface side of the lead sealing hole 3 is stepped and slightly depressed. The glass tablet 8 has a T-shaped cross section with a small diameter portion 8a and a large diameter portion 8b formed coaxially and integrally, with a lead insertion hole 8c extending through the center of the axis. This glass tablet 8 is fitted so that its small diameter portion 8a slightly protrudes below the lead sealing hole 3, and its large diameter portion 8a
b is positioned in point contact with the top surface side peripheral edge 2a of the lead sealing hole 3. Further, the lead 4 is inserted into the lead insertion hole 8c of this tablet 8.
The lower end is placed in contact with the sealing jig 7 and positioned. After being combined in this manner, the glass tablet 8 is heated and melted in a heating furnace, and the leads 4 are sealed in the lead sealing holes 3 as shown in FIG. Looking at this sealed state, the glass 5 is wetly attached to the inner surface of the lead 4 and the lead sealing hole 3,
Its outer surface becomes a smooth free surface due to surface tension during melting. Such a sealed state is obtained because the lower outer edge of the large diameter portion 8b of the glass tablet 8 is locked in point contact with the peripheral edge 2a of the lead sealing hole 3, and the molten glass is This is because the wetting gradually spreads to the inner surface of the lead sealing hole 3 from this contact point. Furthermore, by forming the slightly recessed peripheral edge 2a, the creepage distance _l1 along the glass between the outer lead 4 and the outer ring metal 2 becomes larger than the distance _l2 when the peripheral edge 2a is not formed. , the insulation properties have been significantly improved. Incidentally, if we consider the case where, for example, a cylindrical glass tablet 9 as shown in FIG. 8 is used instead of the above-mentioned irregularly shaped glass tablet 8 having a T-shaped cross section, the glass tablet 9 may melt. As shown in FIG. 9, the glass 9' falls down before the wetting spreads over the upper peripheral edge 2a of the lead sealing hole 3 when the wetting begins. Then, it does not adhere to the peripheral edge portion 2a, and not only is the effect of increasing the creepage distance on the top side not obtained, but also the lower end hits the sealing jig 7, making this portion easy to chip. In addition, this part becomes a rough surface 9a, which makes it easy for dirt to adhere to the outer ring metal 2 during use.
This may cause a shot defect between the lead wire 4 and the lead wire 4. If a spark discharge occurs due to a shot defect when used as an airtight terminal for a refrigerator, this may cause an accident in which the molten sealing glass 5 is ruptured and the high-pressure heat medium inside the compressor is blown out. ,
It is inappropriate to use such a cylindrical glass tablet 9. Problems to be Solved by the Invention When the leads 4 are sealed with glass using the glass tablet 8 having a T-shaped cross section, as shown in FIG. Holes 11 were sometimes formed. Such products must be removed as having a poor appearance, resulting in poor yield. The reason for this is that the organic binder as a binding agent in the glass tablet 8 remains without being completely volatilized during sintering of the glass tablet, and gasifies due to the high temperature during glass sealing, generating bubbles 10. This is because the bubbles 10 cause ruptured holes 11 on the surface of the glass 5. Note that if you raise the sintering temperature or lengthen the heating time in an attempt to completely volatilize the glass tablet, the glass tablet will begin to melt and its shape will change, so this method cannot be used. After investigating the cause of the volatilized residue of the binder mentioned above, it was found that the pressure during press molding, in other words, the large diameter portion 8
It was found that it is influenced by the ratio c/d between the diameter c and the length d of b. For example, in the conventional glass tablet 8, the seventh
The dimensions of each part of the lead sealing hole 3 formed in the outer ring metal 2 shown in the figure, namely the average inner diameter r, depth l, the diameter R of the recessed peripheral portion 2a, and the diameter of the lead 4 to be sealed. Each D is r=6.5mm, l=
5 mm, R = 9 mm, and D = 2.3 mm, glass powder with a weight of 450 mg, which is suitable for the shape of this hole 3 and the diameter of the lead 4 and is optimal for sealing this hole 3, is pressed at a pressure of 1050 to 1200 kg. A glass tablet 8 as shown in FIG. 11 was formed by press molding at / ^cm2 .
The ratio c/d of the diameter c and length d of the large diameter portion 8b is 4.0.
~5.0, and in this case the above-mentioned problem occurred. Means for Solving the Problems As a result of making many samples by varying the press pressure, it was determined that the glass tablet 12 shown in FIG. 1, which can solve the above problems, is as follows. found. In other words, the range in which the binder is almost completely volatilized during combustion of a glass tablet molded under a relatively low predetermined pressure of 800 to 1000 kg/cm ² during press molding is the range in which each part of the lead sealing hole 3 is heated. When the dimensions and the diameter of the lead 4 are the same as those shown in Fig. 7, the weight of the glass that fits the hole and the lead, and the use of an irregularly shaped glass tablet with a T-shaped cross section, the large diameter part The ratio of diameter c to length d of 12b is in the range of c/d=3.0 to 3.5. If this ratio is smaller than this range, the molten glass will creep up along the lead wire, making it difficult to melt the terminal board, and making the glass tablet 12 brittle and easily damaged. If it is made larger, the sintering agent will remain after volatilization. Operation Under the above conditions, when the ratio of the diameter c and length d of the large diameter portion of the glass tablet 12 is set within the above range, the density of the press-molded glass powder decreases and the porosity progresses. The binder is easily volatilized during sintering, so that no binder remains inside the glass tablet, and the generation of air bubbles and the like during lead sealing can be eliminated. In addition, the creeping up of the molten glass onto the lead wire is small, so there is no problem in welding the terminal plate. Furthermore, even if the press pressure is reduced, as long as it is within this range, sufficient binding force will be provided to the press-molded product and it will not be easily damaged. Example Next, the method for manufacturing the glass tablet 12 is as follows.
The flowchart in FIG. 3 will be explained. First, a fine glass powder and an organic binder as a binder are prepared, kneaded in a predetermined ratio, and then granulated using a spray dryer. The glass powder obtained in this way is used in the amount of 450 mg of glass necessary for sealing, depending on the lead sealing hole and lead diameter.
The ratio of the diameter c to the length d of the large diameter portion 12b is 3.0 to 3.5 as described above.
It is molded with a press pressure of 800 to 1000 kg/cm ² so that it becomes . Once the glass powder is shaped by the press in this way, it is taken out from the press mold and sintered in air at a temperature of 500 to 600°C. As a result, the organic binder serving as the binder is sufficiently volatilized, and the glass particles are sintered into a porous state, thereby obtaining the glass tablet 12. Using this glass tablet 12, as shown in FIGS. 6 and 7, if the lead 4 is glass-sealed into the lead sealing hole 3 using a predetermined sealing jig 7, the internal The leads are sealed without air bubbles or surface pores. Next, more specific examples of the method of the present invention will be described. Glass powder weighing 450 mg was pressed at a pressure of 800 to 800 to fit the outer ring metal 2 with the dimensions mentioned above.
Molded with 1000Kg/ ^cm2 , the diameter a of the small diameter part 12a is 4 mm, the length b is 7 mm, and the diameter c of the large diameter part 12b is 10
mm, the length d is 3 mm, and the inner diameter of the lead insertion hole 12c is e.
As a comparative example, the method of the present invention using the glass tablet 12 shown in FIGS. Press the glass powder at a pressure of 1050~
The diameter a of the small diameter part 8a molded at 1200Kg/ ^cm2 is
3.5mm, length d is 8mm, diameter c of large diameter part 8b is 9
mm, the length d is 2 mm, and the inner diameter e of the lead insertion hole 8c is
For each 100 airtight terminals manufactured at the same time by the conventional method using the glass tablet 8 shown in Fig. 11, with a diameter of 2.5 mm and a ratio c/d of the major axis c of the large diameter part 8b to the length d of 4.5. The number of airtight terminals in which air bubbles 10 inside the glass 5 or holes 11 on the surface were generated is shown in the table below.

[Table] As described above, according to the method of the present invention, the generation of bubbles 10 could be reduced to about 1/30, and the generation of holes 11 could be reduced to 1/10, compared to the conventional method. Effects of the Invention According to the present invention, by simply setting the ratio of the diameter and length of the large diameter portion of the glass tablet formed with a predetermined press pressure to an appropriate range, the binder can be removed during sintering of the glass tablet. It is possible to eliminate residual volatilization, and the generation of air bubbles inside the glass and pores on the surface during sealing can be eliminated. Therefore, the yield of this type of hermetic terminal can be improved and costs can be reduced.

[Brief explanation of drawings]

1 and 2 are a front view and a plan view of a glass tablet used in the present invention. Figure 3 shows
3 is a block diagram showing the manufacturing process of the glass tablet shown in FIGS. 1 and 2. FIG. Figures 4 and 5
The figures are a partially sectional front and plan view showing an example of the structure of an airtight terminal to which the method of the present invention is applied. 6 and 7 show a lead sealing process using a glass tablet with a T-shaped cross section, which is the subject of the present invention, and FIG. 6 shows a sealing jig with an outer ring metal, a glass tablet, and FIG. 7 is a sectional view showing a state in which the leads are combined before being sealed, and FIG. 7 is a sectional view showing a state in which the combination shown in FIG. 6 is heat-treated and sealed. Figures 8 and 9 show the case where the leads are sealed with a cylindrical glass tablet.
The figure is a cross-sectional view showing the state before sealing when each part is assembled to the sealing jig, and Fig. 9 is a cross-sectional view showing the state after heat treatment of the assembled parts as shown in Fig. 8. It is. Figure 10 is a cross-sectional view of the lead sealing part of a conventional airtight terminal with bubbles and holes in the sealing glass;
The figure is a front view of a conventional glass tablet. 1...Airtight terminal, 2...Outer ring metal, 3...Lead sealing hole, 4...Lead, 12a...Small diameter part, 1
2b...Large diameter part, 12c...Lead insertion hole, b...
...Diameter of the large diameter section, c...Length of the large diameter section.

Claims (1)

[Claims] 1. Insert the small diameter part of a stepped different diameter glass tablet having a large diameter part and a small diameter part into the lead sealing hole formed in the outer ring metal from above, and align the axial center of the glass tablet. In this method, the lead is inserted and held in a lead insertion hole formed through the glass tablet, and the lead is sealed to glass by heating and melting the glass tablet. The ratio of c to length d is c/d=3.0~3.5
A method for manufacturing an airtight terminal, characterized by: 2. The method of manufacturing an airtight terminal according to claim 1, wherein the press pressure during press molding of the glass tablet is set to 800 to 1000 kg/cm ² .