JP2003207477A - Method of manufacturing glass electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a glass electrode whose strength is enhanced without sacrificing its responsiveness, whose manufacturing process can be automated easily and whose productivity is enhanced. <P>SOLUTION: A porous ceramic 6 is inserted into an open end part 2a at a support tube 2, an exposure face 6b and an exposure face 6c from the open end part 2a at the support tube of the ceramic 6 are immersed wholly in a molten glass 7 in which a response glass is melted, they are pulled out, and a response glass membrane 12 is formed on the exposure faces 6b, 6c of the ceramic 6. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing composite type and monopolar type glass electrodes.

[0002]

2. Description of the Related Art Conventionally, glass electrodes have been used as ion electrodes such as pH electrodes. FIG. 6 shows an example of a conventional glass electrode manufacturing method. In FIG. 6, 30 is a cylindrical support tube, 31 is a response glass heated to have an appropriate viscosity, 32 is a response portion formed by bulging a lump of this response glass by blow molding, and d is a response portion 32. Shows the wall thickness of.

FIG. 6 (A) is a view showing a state in which a response glass 31 containing lithium oxide (Li ₂ O) is attached to the open end of the support tube 30, and FIG. 6 (B) is a response glass 31 attached. It is a figure which shows the state which formed the response part 32 by blowing air in and inflating this. The response portion 32 is blow-molded by a skilled craftsman so as to make the wall thickness d substantially constant, and in order to improve the response of the glass electrode, the area of the response portion 32 should be as wide as possible. It is desirable that d be as thin as possible.

[0004]

However, in order to form a highly responsive glass electrode by the above-mentioned blow molding, the area of the response portion 32 is widened and the wall thickness d is reduced, so that the response portion 32 is formed. 32 was easily broken, and a strength problem occurred.

When the response part 32 is blow molded,
Due to the nature of the responsive glass 31, it is difficult to process, and in order to manufacture a glass electrode with good responsiveness while having appropriate strength, it is necessary to rely on the hands of highly skilled craftsmen, and It was difficult to automate, that is, to improve productivity by using a machine. That is, it has been a cause of raising the manufacturing cost.

Therefore, there has been proposed a method of forming a relatively strong response portion 32 at the tip of the support tube 31 without performing blow molding. FIG. 7: is a figure which shows the manufacturing method of the conventional glass electrode formed in consideration of a strength problem. 33 is a glass tube of response glass.
In addition, FIG.
7 (B) shows a step of welding the glass tube 33 welded to the response portion 32 by cutting the welded glass tube 33 at an appropriate position.
It shows a process of forming.

As shown in FIG. 7A, the glass tube 33 of the response glass is coaxially rotated with respect to the open end of the support tube 30 by using a glass lathe or the like, and is welded by the fire of the gas burner B or the like. . Next, as shown in FIG. 7B, when the glass tube 33 is cut, the gas burner B or the like forms the response portion 32 whose tip portion 32a has an appropriate thickness. Although this manufacturing method is easier than blow molding, it is necessary to use a pump (not shown) for adjusting the pressure inside the support tube 30 in order to properly adjust the wall thickness of the tip portion 32a.

Since the glass electrode shown in FIG. 7 has a special shape in which the thickness of the tip portion 32a is thicker and the strength thereof is higher than that of a general glass electrode, it is excellent in the longitudinal direction shown by the arrow X. Strength can be obtained. However, in order to improve the responsiveness of the response portion 32, the film thickness d ′ on the side surface 32b thereof is made relatively thin and the area thereof is widened. The strength was unavoidable.

Regarding the above-mentioned various glass electrodes,
In recent years, it has been required to reduce the size. However, in order to keep the mechanical strength proper, it is necessary to keep the film thicknesses d and d ′ of the response part 32 appropriate, and in order to have sufficient responsiveness with this film thickness, a certain area is required. This hinders miniaturization.

The present invention has been made in consideration of the above matters, and an object thereof is to significantly improve the strength without sacrificing the responsiveness and to easily automate the manufacturing process. Another object of the present invention is to provide a method of manufacturing a glass electrode which can improve productivity.

[0011]

According to a first aspect of the present invention, there is provided a method of manufacturing a glass electrode, wherein a porous ceramic is inserted into an open end portion of a support tube, and all exposed surfaces of the ceramic from the open end portion of the support tube. It is characterized in that the response glass film is formed on the exposed surface of the ceramic by immersing in the molten glass obtained by melting the response glass and then withdrawing it.

That is, the porous ceramic located at the tip of the glass electrode is directly immersed in the molten glass obtained by melting the response glass and then withdrawn, whereby the response glass is welded to the ceramic as thinly as possible. You can Further, the response glass is in a state of being lined with a tough ceramic, so that the strength can be increased without increasing the thickness of the response glass. In addition, the blow molding process is eliminated from the manufacturing process, which facilitates mechanization and improves productivity.

In the method of manufacturing a glass electrode according to the second aspect of the present invention, porous ceramic is inserted into the open end of the support tube with a part thereof protruding, and the glass ceramic is exposed to the open end of the support tube. It is characterized in that a glass tube is inserted and one end of the response glass is heated to be welded to the support tube, and the other end of the response glass is heated to be closed so as to cover the exposed portion of the ceramic.

That is, by using the tube of the response glass to close the exposed portion of the ceramic so as to cover it, the response portion of the response glass can be formed more easily than by blow molding. Moreover, since the response glass forming the response portion is formed along the ceramic, it is possible to prevent the damage. Also in this case, a glass electrode having both thinness and strength can be manufactured.

When the responsive glass and the ceramic have the same coefficient of thermal expansion, it is possible to prevent the occurrence of cracks. As the ceramic having a temperature expansion coefficient similar to that of the response glass, for example, a zirconia-based porous ceramic can be used. In addition, it is desirable that the difference between the two coefficients of thermal expansion is about ± 10%.

After forming the responsive glass membrane, injecting an internal liquid into the support tube and depressurizing the inside of the support tube to discharge the air that has entered between the ceramics and allow the internal liquid to permeate. Since the internal liquid can permeate into the pores of (1), the liquid contact area of the internal liquid with respect to the response glass membrane can be widened, and thereby the accuracy of the glass electrode can be improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining the overall structure of a pH glass electrode 1 manufactured by the manufacturing method of the present invention.
In FIG. 1, 2 is a support tube made of, for example, lead glass, 3 is a response part formed at one end of the support tube 2, 4 is a grip formed at the other end of the support tube 2, 5
Is a signal cable.

FIG. 2 is a view showing a step of forming a response portion 3 by inserting a ceramic into one end of the support tube 2, and 6 is a porous material which is welded in a state of being inserted into the open end of the support tube 2. Ceramic 7 is molten glass that melts the glass used as response glass at high temperature, 8 is a platinum crucible that accommodates the molten glass 7 in a heated state, 9 is a platinum crucible 8
It is a heater that supplies heat to the.

The support tube 2 is a cylindrical body made of a material having chemical resistance and having a heat resistance comparable to or higher than that of the response glass. In this example, the support tube 2 is made of lead glass, but may be a metal or ceramic cylinder such as zirconia.

The ceramic 6 is made of a material having a temperature expansion coefficient similar to that of the response glass,
In the case of this example, it is a zirconia-based ceramic, and its temperature expansion coefficient is 80 to 90 × 10 ⁻⁷ / ° C. On the other hand, the temperature expansion coefficient of the response glass to be melted as the molten glass 7 in this example is 97.6 × 10 ⁻⁷ / ° C. That is, the temperature expansion coefficient of the ceramic 6 and the response glass is ± 10.
It is desirable to be within%. Note that the present invention does not limit the materials such as the ceramic 6 and the molten glass 7 by this description.

Since the ceramic 6 is porous and has a large number of pores, the internal liquid can be introduced into the pores. The shape is a columnar shape having an outer diameter substantially equal to the inner diameter of the support tube 31, and a part 6a of the side surface portion thereof.
Is inserted into the support tube 2, and another portion 6b of the side surface is attached so as to project from the open end of the support tube 2. Further, a chamfered portion 6c (a hemispherical body or a substantially hemispherical body portion) is formed at the lower end portion of the ceramic 6 to eliminate a corner.

The side surface portion 6b and the chamfered portion 6c are exposed ceramic surfaces exposed from the open end of the support tube 2,
By mounting the ceramic 6 so as to protrude from the support tube 2, the areas of the exposed surfaces 6b and 6c are increased.

The crucible 8 is softened at 619 ° C., for example, and the temperature of the molten glass 7 of this example is set to 1200 to 1300.
It is heated to ℃, by this, molten glass 7
Reduce the viscosity of to make it smooth. The crucible 8 does not have to be a platinum crucible, and a crucible made of an appropriate material can be used as long as it has sufficient heat resistance.

FIG. 2A is a diagram showing a step of inserting the ceramic 6 into the open end of the support tube 2. That is, as shown by the arrow 10, a column of ceramic 6 having an outer diameter substantially equal to or slightly smaller than the inner diameter is inserted from below the open end of the support tube 2 to the open end thereof to heat the tip of the support tube 2. Then, by caulking from the outer periphery, the side surface portion 6a is welded to the inner peripheral surface at the tip of the support tube 2.

Next, FIG. 2 (B) is a view showing a step of directly immersing the molten glass 7 from the open end of the support tube 2 to the lower end of the ceramic 6 (all exposed surfaces 6b and 6c) and then pulling it out. Is. That is, as indicated by a double-headed arrow 11, the entire exposed surface of the ceramic 6 is immersed in the molten glass 7 and taken out to melt the entire exposed surface of the ceramic 6 as the molten glass 7.
Can be surely covered by. At this time, the response glass 12 is securely bonded to the support tube 2 by immersing the lower end portion 2a of the support tube 2 in the molten glass 7.

Further, the film thickness d ₁ and d ₂ of the response glass 12 to be formed can be changed by changing the speed at which the ceramic 6 is inserted into the molten glass 7, the immersion time, and the speed at which it is pulled up. It can be set freely. Furthermore, in the above process, it is possible to suck some of the melted response glass 12 into the ceramic 6 by sucking the inside of the support tube 2, and the joined surface of the response glass 12 and the ceramic 6 when cooled down. Can be made stronger and the liquid contact area with the internal liquid described later can be maximized.

FIG. 2C is a diagram showing a cooling process of the response glass 12. The formed response glass 12 can be cooled, for example, at an annealing temperature. That is, for example, the strain of the response glass 12 can be reduced and the strength thereof can be further increased by leaving it in an environment where the ambient temperature is 420 ° C. for a predetermined time.

Steps shown in FIGS. 2A to 2C described above
Is a compound that requires special technology like conventional blow molding.
This series of processes is fully automatic without the need for rough movements.
It can be easily realized by the sequence control of. Sanawa
Eliminate manufacturing processes that rely on traditional craftsmanship
The manufacturing cost can be reduced as much as possible.
In addition, the response file created by the same procedure by automation is used.
The lath 12 has a film thickness d ₁, D₂Easy to align
It is possible to make the glass electrode 1 uniform.
Is.

Further, the glass electrode 1 formed by the above-described manufacturing method is formed by welding the responsive glass 12 to the surface of the robust ceramic 6, so that the responsive glass 12 is lined with the ceramic 6 as it were. Film thickness d
_{Even if 1} and d ₂ are extremely thin, they are not easily damaged. That is, it is possible to dramatically improve the robustness of the response section 3 while reducing the film thicknesses d ₁ and d ₂ to ensure sufficient responsiveness.

In addition, in the glass electrode 1 of this embodiment, most of the exposed surface 6b, 6c of the ceramic 6 is exposed from the support tube 2, and the exposed portion is entirely covered with the response glass 12. The surface area of the glass 12 is increased, which can improve the responsiveness.

Further, since the chamfered portion 6c having a smooth curved surface is formed on the lower end portion of the ceramic 6, the response glass 12 formed on the surface of the chamfered portion 6c does not have a corner. Further, the impact due to a collision is not always concentrated on one point, and further robustness can be obtained. Further, although not required, the response glass 12
If the film thickness d ₁ at the bottom is thicker than the film thickness d ₂ at the side surface, it is possible to form the response part 3 that is particularly stronger against an impact from below.

FIG. 3 is a diagram for explaining another step of the glass electrode manufacturing method. In FIG. 3, 13 is a closed container capable of vacuuming, 14 is a vacuum pump, and 15 is an internal liquid injected into the support tube 2.

As shown in FIG. 3, the internal liquid 1 is placed in the support tube 2.
After injecting 5, this is set in the closed container 13. Then, the vacuum pump 14 is evacuated,
When this is placed under a reduced pressure atmosphere, the air entering the small holes in the ceramic 6 is discharged as bubbles 16.
After that, by returning the pressure in the closed container 13 to the original atmospheric pressure again, the inner liquid 15 is filled up to the tip of the ceramic 6. That is, the film of the response glass 12 can be brought into sufficient contact with the internal liquid 15 to make electrical contact.

It should be noted that, in the above step, various additional devices may be provided for performing the above step, such as a stand for raising the support tube 2 and a heater for preventing the internal liquid 15 from freezing. Will not be described in detail.

FIG. 4 is a diagram showing a subsequent manufacturing process of the glass electrode 1, 17 is an internal electrode immersed in the internal liquid 15, 18 is a lead wire, 19 is a bush for holding the lead wire 18, and 20 is a cable. 5 is a cap for fixing 5 to the support tube 2.

FIG. 4 (A) shows the support tube 2 in the state where the pressure reducing step has been completed, and FIG. 4 (B) shows the step of inserting the internal electrode 17 into the support tube 2. FIG. 4C shows a step of inserting the bush 19 and a step of closing the upper end 2b of the support tube 2 using the cap 20.

By inserting the bush 19 into the support tube 2 and molding the resin in the space above the bush in the support tube 2, leakage of the internal liquid 15 can be prevented and the lead wire 18 can be fixed. This allows the glass electrode 1 to be laid down in the lateral direction and stored. Further, even if the cable 5 is completely sealed by the cap 20 and the positional relationship between the cable 5 and the support tube 2 is fixed, even if a tensile force is applied to the cable 5, the internal electrode 1
7 is never pulled out.

Further, by adding further manufacturing steps such as attaching the grip 4 to the outside of the cap 20 and attaching a sheath tube for protecting the support tube 2 and the response section 3, a glass having more robustness is obtained. It is also possible to manufacture the electrode 1.

FIG. 5 is a diagram showing another example of the glass electrode manufacturing method of the present invention. 5, the same parts as those in FIGS. 1 to 4 are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG. 5, 33 is a tube made of response glass, and B is a partial heating device such as a gas burner. It should be noted that these members 33 and B are the same as those described in the prior art of FIG.

FIG. 5A shows the response glass tube 33.
Inserting the porous ceramic 6 into the lower end portion 2a (open end portion) of the support tube 2 with a part thereof protruding.
The response glass tube 33 is inserted into the ceramic 6 exposed from the open end 2a of the support tube 2, and the response glass 3
It is a figure which shows the process of heating the one end 33a of 3 and welding to the support tube 2.

At this time, the response glass tube 33 and the support tube 2 are welded by heating the response glass 33 with the gas burner B while rotating both the response glass tube 33 and the support tube 2 coaxially. And the responsive glass tube 33 can be firmly joined to the ceramic 6.

FIG. 5B shows a step of heating the other end 33b of the response glass tube 33 to close it so as to cover the exposed portion of the ceramic 6. That is, the response glass tube 33 is welded by a burner flame such as a gas burner B and the lower end surface is sealed, so that the lower end portion 33b of the response portion 3 is formed.
To mold.

At this time, the response glass 33 is the gas burner B.
Even if it is heated and softened by, for example, the ceramic 6 is inserted into the inside thereof, so that the shape of the response portion 3 can be surely maintained in a bottomed cylindrical shape. Also in this example, a hemispherical chamfer may be formed at the lower end of the ceramic 6 as in the example shown in FIGS. Further, the inner shape of the lower end portion 33b of the response glass 33 is also the ceramic 6
Since the shape of the lower end portion of the support tube 2 is surely maintained, it is not necessary to appropriately pressurize the inside of the support tube 2 unlike the conventional blow molding.

Therefore, the glass electrode 1 can be manufactured relatively easily by carrying out the glass electrode manufacturing method shown in this example, and this manufacturing process can be carried out by fully automatic sequence control. That is, no craftsmanship is required in manufacturing the glass electrode 1, and the manufacturing cost can be reduced accordingly.

Since the response glass 33 is formed along the ceramic 6, the strength of the glass electrode 1 can be improved even if the thickness of the response glass 33 is reduced.

[0046]

As described above, according to the present invention,
Since the response portion can be formed by the response glass backed by the ceramic, it is possible to form a tough response glass film having resistance to impact from all directions. Moreover, since the thickness of the response glass remains thin, the glass resistance is low and the response is excellent. In addition, in the method for manufacturing a glass electrode of the present invention, it becomes possible to omit the step of blowing the response glass film, which requires craftsmanship, has good workability, and is capable of fully automatic processing by a machine, thus improving productivity. improves. Further, it becomes possible to standardize the products manufactured by the determined process.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a glass electrode of the present invention.

FIG. 2 is a diagram showing an example of a method for manufacturing the glass electrode.

FIG. 3 is a diagram showing a continuation of the method for manufacturing the glass electrode.

FIG. 4 is a diagram showing a continuation of the method for manufacturing the glass electrode.

FIG. 5 is a diagram showing another method of manufacturing a glass electrode.

FIG. 6 is a diagram illustrating a conventional method of manufacturing a glass electrode.

FIG. 7 is a diagram illustrating another conventional method for manufacturing a glass electrode.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass electrode, 2 ... Support tube, 2a ... Open end, 6 ... Ceramic, 6b, 6c ... Exposed surface, 7 ... Molten glass, 12
... Responsive glass (membrane), 15 ... Internal liquid, 16 ... Air (air bubbles), 33 ... Responsive glass tube.

Claims (4)

[Claims] 1. A porous ceramic is inserted into the open end of a support tube, and the entire exposed surface of the ceramic from the open end of the support tube is immersed in a molten glass obtained by melting the responsive glass. Is formed to form a responsive glass film on the exposed surface of the ceramic. 2. A porous glass ceramic is inserted into the open end of the support tube with a part thereof protruding, and a response glass tube is inserted into the ceramic exposed from the open end of the support tube. A method of manufacturing a glass electrode, characterized in that one end of glass is heated and welded to a support tube, and the other end of response glass is heated and closed so as to cover an exposed portion of ceramic. 3. The method for producing a glass electrode according to claim 1, wherein the coefficient of thermal expansion of the responsive glass and that of the ceramic are substantially the same. 4. The method according to claim 1, wherein after forming the responsive glass film, an internal liquid is injected into the support tube, and the inside of the ceramic is depressurized to expel the air entering between the ceramics to permeate the internal liquid. 4. The method for manufacturing a glass electrode according to any one of 3 to 3.