JPH09288081A - Probe and device for continuously measuring oxygen in molten metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a probe and device capable of continuously and stably measuring oxygen in a molten metal with high accuracy over a long time. SOLUTION: In a measuring part 11, a sheath thermocouple 2 also used as an internal electrode is inserted into a solid electrolyte pipe 4 closed at its lower end and a solid electrolyte pipe 4 is packed with a reference substance 3 composed of Mo and MoO2 . An internal protective pipe 5 is fitted to the upper end part of the solid electrolyte pipe 4 and the sheath thermocouple 2 of the part led out of the solid electrolyte pipe 4, and the upper end part of the solid electrolyte pipe 4 is fitted to the lower end part of the internal protective pipe 5. Both of them are fixed by a fixing agent such as refractory cement. An external protective pipe 6 also used as an external electrode is externally fitted to the internal protective pipe 5 and the solid electrolyte pipe 4, and slits 7a, 7b are formed to the lower part of the external protective pipe. The width of these slits is 1/4 or more the outer diameter of the solid electrolyte pipe 4 and below 1/3 the outer diameter of the external protective pipe 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe and a measuring device for continuously measuring oxygen in molten metal capable of continuously measuring the amount of oxygen in molten metal such as molten copper for a long period of time. The present invention relates to a probe and a measuring apparatus for continuously measuring oxygen in molten metal, which is suitable for the case where

[0002]

2. Description of the Related Art FIG. 9 is a schematic sectional view showing a conventional oxygen measuring probe for measuring the amount of oxygen in molten metal.
As shown in FIG. 9, a conventional oxygen measuring probe has a solid electrolyte tube 73 whose one end is closed in the center, and a platinum wire is placed inside the closed lower end in the solid electrolyte tube 73. A lead wire 74 made of, for example, is connected. Further, an external protection tube 71 that protects the solid electrolyte tube 73 and serves as an external electrode is provided on the outer peripheral portion of the solid electrolyte tube 73, and the lower portion of the solid electrolyte tube 73 is a fixing agent 72 made of refractory cement or the like. By external protection tube 7
It is fixed in 1. And one end is the solid electrolyte tube 7
A voltmeter 79 is connected between the other end of the lead wire 74, which is connected to the inner lower end of 3, and the upper end of the external protective tube 71.

In the oxygen measuring probe constructed as described above, a gas (standard gas) having a known oxygen concentration, such as air, oxygen gas or a mixed gas containing oxygen, is supplied into the solid electrolyte tube 73. On the other hand, when the measurement part formed at the lower end of the oxygen measuring probe is immersed in the molten metal 75, an oxygen concentration battery using the standard gas as a reference electrode with a known oxygen partial pressure is formed, and inside and outside the solid electrolyte tube 73. Electromotive force is generated at both interfaces. This electromotive force can be measured by a voltmeter 79 connecting the lead wire 74 and the external protection tube 71,
From that value, the oxygen concentration in the molten metal can be known by calculation.

By the way, in the case of measuring molten copper containing almost no impurities, when the lower end portion of the oxygen measuring probe shown in FIG. 9 is immersed in the molten copper, the fixing agent 72 comes into contact with the molten copper 75 for measurement. Over a long period of time, the fixing agent 72 reacts with the molten copper to affect the electromotive force, and the fixing agent 72 mixes with the molten copper 75, deteriorating the properties of the product produced from this molten copper 75. Will end up.

Therefore, Japanese Laid-Open Patent Publication No. 55-98351 discloses the following oxygen measuring probe.
That is, in the case of immersing the measuring part of the oxygen measuring probe in the molten metal, in order to prevent the fixing agent from coming into contact with the molten metal, as shown in FIG.
The solid electrolyte tube 73 is arranged and fixed so that the end of the outer protection tube 71 does not protrude from the lower end surface of the outer protection tube 71, and a predetermined space 76 is formed inside the lower end portion of the outer protection tube 71, and gas remains therein. Let Further, in order for the lower end of the solid electrolyte tube 73 to come into stable contact with the molten metal 75, a minimum necessary slit 77 or through hole 78 is formed in the lower end of the external protection tube 71 as shown in FIG. ing.

In Japanese Utility Model Publication No. 2-40536,
There is disclosed an oxygen measuring probe in which a molten metal filter having cells such as slits is provided on the outer peripheral surface of the lower end portion of the outer protective tube.

[0007]

However, FIG.
In the oxygen measuring probe disclosed in JP-A-55-98351 shown in FIGS.
Can contact the molten metal 75, but has the following drawbacks.

That is, when the size of the slit 77 or the through hole 78 is smaller than the sizes of the outer protective tube 71 and the solid electrolyte tube 73, the molten metal is not contained in the outer protective tube 71 during measurement. Cannot flow in and out smoothly from the outside to the inside and from the inside to the outside. That is,
The molten metal that has flowed into the external protection tube 71 at the beginning of the measurement stays inside the external protection tube 71, and this molten metal and the molten metal outside the external protection tube 71 cannot be smoothly circulated. .

Usually, since the molten metal in the molten metal bath is not in a uniform composition state, in order to measure the oxygen concentration in the molten metal with high accuracy, the molten metal in contact with the solid electrolyte tube 73 is circulated. It is necessary to always allow fresh molten metal, that is, molten metal that has not yet contacted the solid electrolyte tube 73, to contact the solid electrolyte tube 73.

On the other hand, when the size of the slit 77 or the like is larger than the size of the outer protective tube 71 or the like, the molten metal should smoothly flow in and out of the outer protective tube 71. However, if a large amount of molten metal flows into the outer protective tube 71, it is not possible to maintain the space 76 in which gas remains inside the outer protective tube 71, so that the fixative 72 becomes molten metal 75. Will come into contact.

Moreover, depending on the size of the slit,
The following problems occur. That is, if the width of the slit 77 is too large, the lower end portion of the external protection tube 71, which is a region where no slit is formed, bends inward due to the pressure of the flow of the molten metal, and contacts the solid electrolyte tube 73. Or, in the worst case, the lower end of the external protection tube 71 may be broken. On the other hand, if the oxygen measuring probe with the width of the slit 77 being too small is continuously used for a long time, the lower end portion of the external protection tube 71 contracts and the slit 77 is closed.

Further, in the oxygen measuring probe disclosed in Japanese Utility Model Publication No. 2-40536, a molten metal filter is provided to protect the solid electrolyte from molten slag. If it is used over a long period of time, the filter may be clogged, so that the molten metal cannot be stably brought into contact with the solid electrolyte tube.

The present invention has been made in view of the above problems, and it is possible to measure oxygen continuously in a molten metal with high accuracy and to perform stable measurement even when used for a long time. The purpose is to provide a device.

[0014]

A probe for continuously measuring oxygen in molten metal according to the present invention comprises a solid electrolyte tube of one-end closed type, a sheath thermocouple inserted into the solid electrolyte tube and also serving as an internal electrode, A reference substance filled in the solid electrolyte tube, and a protective tube that is also fitted to the solid electrolyte tube and also serves as an external electrode, and has a width or a diameter of the outer diameter of the solid electrolyte tube at the tip of the protective tube. It is characterized in that a plurality of slits or through holes having a diameter of 1/4 or more and less than 1/3 of the outer diameter of the protective tube are formed.

Further, a reinforcing member is attached to the tip of the protection tube, and the width or diameter is 1/5 or more of the outer diameter of the solid electrolyte tube and 3 of the outer diameter of the protection tube at the tip of the protection tube. / 5
A plurality of slits or through holes, which are less than the above, may be formed.

Further, the slit preferably has a ratio of a length of the solid electrolyte tube exposed in the slit to a length of the slit of 1: 7 to 6: 7, and the protective tube. Inside, there is an internal protection tube that covers the upper end of the solid electrolyte tube and the portion of the sheath thermocouple led out from the solid electrolyte tube, and the internal protection tube is the solid electrolyte tube at its lower end. It is preferably fitted and fixed to the upper end portion of the.

Furthermore, it is preferable that the reinforcing member is a rod-shaped or plate-shaped member bridging the slit at one or a plurality of positions at the tip of the protective tube having the slit formed therein. It is preferable that the body is formed of a ring-shaped member, and the reinforcing body is fitted and fixed to the tip end portion of the protection tube.

An apparatus for continuously measuring oxygen in molten metal according to the present invention comprises a probe for continuously measuring oxygen in molten metal as described above,
An arithmetic processing unit for obtaining the oxygen activity and the temperature of the molten metal from the electromotive force and the temperature signal measured by the probe,
First display means for displaying the oxygen activity and the temperature of the molten metal obtained by the arithmetic processing means over time, second display means for displaying only the oxygen activity, and intermittently measuring at regular intervals And a third display unit for displaying the oxygen activity and the temperature of the molten metal obtained by the arithmetic processing unit from the generated electromotive force and the temperature signal.

[0019]

In the probe for continuous oxygen measurement according to the present invention, since a plurality of slits or through holes having a predetermined shape are formed at the tip of the protective tube in the measuring portion, the molten metal inside and outside the protective tube is smoothed. Can be circulated to the solid electrolyte tube at all times. Therefore, the oxygen concentration in the molten metal can be measured with high accuracy.

By attaching a reinforcing member to the tip of the protective tube, the range of shape and size of the slit or the like that can be formed can be further widened.

Further, by setting the ratio of the length of the solid electrolyte tube exposed from the upper end of the slit to the length of the slit in the tube axis direction within a predetermined range, the tip of the solid electrolyte tube can be protected. The molten metal to be measured can be sufficiently brought into contact with the solid electrolyte tube. Therefore, the oxygen concentration in the molten metal can be measured with high accuracy.

Furthermore, by fitting and fixing the upper end portion of the solid electrolyte tube to the lower end portion of the internal protection tube, the solid electrolyte tube can be held without coming into contact with the inner surface of the protection tube. It is possible to prevent an external force or the like from being applied by the protective tube. Therefore, it is possible to prevent breakage or the like from occurring in the solid electrolyte tube.

Next, the relationship between the shape of the slit or the through hole formed at the tip of the protective tube and the solid electrolyte tube and the protective tube will be described.

Width of Slit and Diameter of Through Hole The width of the slit formed at the tip of the protective tube and the size of the diameter of the through hole have a great influence on the measurement accuracy. That is, when the molten metal is kept in contact with the solid electrolyte tube at the time of measurement, the measurement can be performed with high accuracy. For this reason, it is necessary to form a slit or the like having a certain size or more, and if the shape of the slit or the like is too small, there is a possibility that the slit or the like may be blocked during measurement by slag or the like. In order to supply such a fresh molten metal and prevent the slit from being closed, the width of the slit and the diameter of the through hole are set to 1/4 of the outer diameter of the solid electrolyte tube.
It is necessary to do the above.

The width of the slit and the diameter of the through hole also affect the strength of the protective tube. That is, contrary to the above, if the shape of the slit or the like is too large, the area of the tip portion of the protective tube where the slit is not formed becomes small, and this portion is easily deformed during measurement. Will end up. In order to prevent such deformation of the protective tube, it is necessary to make the width of the slit and the diameter of the through hole less than 1/3 of the outer diameter of the protective tube.

Therefore, the width of the slit or the diameter of the through hole formed at the tip of the protective tube is at least 1/4 of the outer diameter of the solid electrolyte tube and less than 1/3 of the outer diameter of the protective tube. .

When the shape of the slit or the like is increased beyond the above range or below the above range, it is effective to attach a reinforcing member to the tip of the protective tube. As the reinforcing member, for example, a rod-shaped or plate-shaped member that connects the distal end portion of the protective tube where no slit is formed in a bridging manner, or a band-shaped ring may be used. . When such a reinforcing member is used, the width of the slit or the diameter of the through hole formed at the tip of the protective tube is 1/5 or more of the outer diameter of the solid electrolyte tube and less than 3/5 of the outer diameter of the protective tube. Can be

Dew of solid electrolyte tube with respect to slit length
The length of the protruding portion The portion of the solid electrolyte tube exposed from the slit formed at the tip of the protective tube affects the measurement accuracy and protection of the solid electrolyte tube. That is, if the exposed portion of the solid electrolyte tube is small, or if the measuring portion of the oxygen measuring probe is configured such that the lower end of the solid electrolyte tube is located above the upper end of the slit, the measuring portion at the time of measurement Even if the molten metal is immersed in the molten metal, it may not be possible to bring the molten metal into contact with the solid electrolyte tube, resulting in a decrease in measurement accuracy. Therefore, the ratio of the length of the exposed portion of the solid electrolyte tube to the length of the slit is preferably 1: 7 or more. Conversely, if the exposed portion of the solid electrolyte tube is longer than the length of the slit, that is, if the lower end of the solid electrolyte tube protrudes from the lower end surface of the protection tube, the solid electrolyte tube is damaged when handling the oxygen measurement probe. It may happen. For this reason, the length of the exposed portion of the solid electrolyte tube is preferably shorter than the length of the slit, and the ratio thereof is preferably 6: 7 or less.

Therefore, the length of the exposed portion of the solid electrolyte tube and
The ratio to the length of the slit is within the range of 1: 7 to 6: 7.

In the oxygen continuous measuring apparatus according to the present invention, the arithmetic processing means determines the oxygen activity and the oxygen activity based on the electromotive force and the molten metal temperature signal generated by immersing the measuring portion of the oxygen measuring probe in the molten metal. Calculate the temperature of the molten metal. Then, the oxygen activity and the molten metal are displayed on each display unit at appropriate times. By installing this oxygen continuous measuring device in one or more places on the production line of products made of molten metal, it is possible to obtain the necessary oxygen value and temperature information accurately, so that high quality and high accuracy can be obtained. The product can be manufactured.

[0031]

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing an oxygen measuring probe 1 according to an embodiment of the present invention. Also,
FIG. 2 shows a measuring part (sensor part) 11 of the oxygen measuring probe 1.
FIG. As shown in FIGS. 1 and 2, the oxygen measuring probe 1 is roughly divided into a measuring unit 11 and a measuring unit 11.
And a terminal portion.

A solid electrolyte tube 4 having a closed lower end is arranged in the center of the measuring section 11, and the tip of the sheath thermocouple 2 which also serves as an internal electrode is inserted into the solid electrolyte tube 4. There is. Further, the solid electrolyte tube 4 is filled with a reference substance 3 made of Mo, MoO2 or the like. The upper end of the solid electrolyte tube 4 and the portion of the sheath thermocouple 2 led out from the solid electrolyte tube 4 are fitted by an inner protective tube 5, and the lower end of the inner protective tube 5 has a solid electrolyte tube 4 The upper ends of the two are fitted together, and both are fixed by a fixing agent such as refractory cement. An external protection tube 6 that also serves as an external electrode is externally fitted to the internal protection tube 5 and the fixed electrolyte tube 4, and a slit 7a extending in the tube axis direction is formed at the lower end of the external protection tube 6. 7b is formed. On the other hand, in the terminal part, a terminal box 10 provided with a lid
A terminal block 9 having output terminals to the outside is installed therein, and a socket 8 is screwed to the bottom of a terminal box 10.
The upper end of the outer protective tube 6 is screwed to the lower portion of the socket 8, and the upper end of the inner protective tube 5 is fixed with cement or the like. Further, the upper portion of the sheath thermocouple is inserted through the socket 8 and the terminal block 9, and its tip is wired to a predetermined terminal.

When the oxygen amount of the molten metal is measured by the oxygen measuring probe constructed as described above, first, the measuring portion 11 is directed downward, and the tip portion is immersed in the molten metal. Then, an oxygen concentration battery using the sheath thermocouple 2 as a reference electrode is formed, and between the inner peripheral surface of the solid electrolyte tube 4 in contact with the reference substance 3 and the outer peripheral surface of the solid electrolyte tube 4 in contact with the molten metal. Electromotive force is generated. The generated electromotive force is led to the upper terminal portion through the sheath thermocouple 2 that is in contact with the reference material 3 and the external protection tube 6 that is in contact with the molten metal, and is detected at this terminal portion.

In the measuring part of the oxygen measuring probe according to this embodiment, the solid electrolyte tube is not directly fixed in the outer protective tube as in the conventional case, but the solid electrolyte tube 4 is provided at the lower end of the inner protective tube 5. Although the upper end of the solid electrolyte tube 4 is fitted and fixed and a fixing agent is used for this fitting portion, the solid electrolyte tube 4 is attached so as to extend downward from the fitting portion, and the inner surface of the outer protective tube 6 is Held without touching.
Therefore, there is no risk that the refractory cement will be mixed into the molten metal during the measurement, and since the molten metal can be sufficiently brought into contact with the outer peripheral surface of most of the solid electrolyte tubes, oxygen in the molten metal can be highly accurately measured. Can be measured at. Further, during measurement, external pressure due to distortion of the external protection tube 6 does not act on the solid electrolyte tube, so that the solid electrolyte tube 4 is broken or the thermocouple wire is disconnected due to the distortion of the solid electrolyte tube. It is possible to prevent such a thing.

Further, slits 7a and 7b having a predetermined shape are formed at the lower end portion of the external protection tube 6. That is, the width of the formed slits 7 a and 7 b is 1/4 or more of the outer diameter of the solid electrolyte tube 4 and 1 of the outer diameter of the outer protective tube 6.
By setting the ratio to be less than / 3, the molten metal whose oxygen content is to be measured does not stay in the outer protective tube 6, and fresh molten metal can be constantly circulated and contacted with the outer surface of the solid electrolyte tube 4.

Next, as a second embodiment, the external protection tube 6
An oxygen measuring probe having a reinforcing member attached to the lower end of the will be described. FIG. 3 is a side view showing an example of a sensor unit in which a reinforcing member is attached to the measuring unit of the oxygen measuring probe,
(A) shows the case where the reinforcing body is attached to the lower end surface of the external protective tube, and (b) shows the case where the reinforcing body is attached near the lower end of the external protective tube. Further, FIG. 4 is a bottom view of the oxygen measuring probe in which various reinforcing members are attached to the lower end surface of the external protection tube.

The slit formed at the lower end of the external protection tube is required to have a predetermined width in order to prevent breakage of the lower end of the external protection tube during measurement. 3A and 4A to 4D, the lower end surface of the outer protective tube 6 in which the slits 7a and 7b are not formed is required. In, the reinforcing body 31 made of a bar or plate is attached so as to bridge a plurality of locations.

The reinforcing body is not only attached to the lower end surface of the outer protective tube 6 but also the lower end tip portion of the outer protective tube 6 is inserted like a reinforcing body 32 formed of a band-shaped ring. Good. Further, a plurality of such reinforcing members 32 may be fitted into the lower end tip portion of the external reinforcing member 6.

The reinforcing body is not limited to the above-mentioned reinforcing bodies 31 and 32, but the outer protective tube is ensured while ensuring the flow of the molten metal so that fresh molten metal always comes into contact with the solid electrolyte tube. Any material can be used as long as it can prevent the lower end portion of the slit from deforming and the slit from contracting and closing.

Next, an apparatus for measuring oxygen in molten metal using the above-mentioned oxygen measuring probe will be described. FIG. 6 is a schematic configuration diagram showing an apparatus for continuously measuring oxygen in molten metal according to an example of the present invention. As shown in FIG. 6, the measuring portion of the oxygen measuring probe 41 is immersed in the molten metal 44 flowing in the gutter 43, and the oxygen measuring probe 41 is fixed to the pedestal 42 in this state.

The electromotive force and the temperature signal measured by the oxygen measuring probe 41 are input to the arithmetic processing unit 45, and the arithmetic processing unit 45 calculates the oxygen activity and the temperature of the molten metal in real time. In this arithmetic processing unit 45, the oxygen activity of the molten metal (molten copper) is calculated by the following mathematical formula 1.

[0042]

[Equation 1] a _o = exp [-ΔG ^o / RT] ・ [(Pθ ^1/4 + P _ref ^1/4 ) exp [-E
F / RT] -Pθ ^1/4 ] ² a _o : Oxygen activity in molten copper E: Electromotive force T: Absolute temperature R: Gas constant F: Faraday constant Pθ: Oxygen partial pressure at which ion conduction and electron conduction are equal Pref : Equilibrium oxygen partial pressure of reference substance ΔG ^o : Change in free energy due to dissolution in molten copper

Pref in the above formula 1 represents the equilibrium oxygen partial pressure of the reference substance, and FIG.
FIG. 7 is a graph showing the correlation between the oxygen activity calculated when the value of aschewski is used on the vertical axis and the product analysis value on the horizontal axis. As shown in FIG. 5, Pre
Using Kubaschewski's value for f, the product analysis and oxygen activity were in good agreement. Therefore, it is preferable to adopt the value of Kubaschewski as Pref.

The arithmetic processing unit 45 outputs these arithmetic values to the respective display units 46, 47 and 48 to display them. The first display device 46 displays the calculated oxygen value and the temperature, the second display device 47 displays only the calculated oxygen value, and the third display device 48 intermittently measures the electromotive force. And the oxygen activity and the temperature of the molten metal obtained by the arithmetic processing unit 45 from the temperature signal.

By installing the oxygen continuous measuring device configured as described above at one place or a plurality of places in the production line of the product made of molten metal, labor saving in operation can be achieved and stable operation can be realized. Can be realized. In addition, since the required oxygen value and temperature information are accurately displayed on each production line, high quality and highly accurate products can be produced.

Next, the result of actually measuring the oxygen content of the molten metal using the oxygen measuring probe will be described in comparison with a comparative example outside the scope of the claims.

First Embodiment FIG. 7 is a cross-sectional view showing a measuring portion of the oxygen measuring probe according to the present embodiment, which is constructed without using an internal protective tube. As shown in FIG. 7, a solid electrolyte tube 54, the lower end of which is closed, is arranged in the center of the measuring section, and the tip of the sheath thermocouple 52 is inserted into the solid electrolyte tube 54. There is. Further, in the solid electrolyte tube 54, M
A reference substance 53 composed of o and MoO 2 is filled. The solid electrolyte tube 54 is fixed in the outer protective tube 56 by a fixing agent 58 such as refractory cement.
Further, a slit 57 is formed at the lower end portion of the external protective tube 56, and a reinforcing body 51 is attached to the lower end surface of the external protective tube 56.

The outer and inner diameters of the solid electrolyte tube 54 were 10 mm and 6 mm, respectively, and the outer and inner diameters of the outer protective tube 56 were 25 mm and 21 mm, respectively. In addition, the distance T from the lower end of the fixative 58 to the lower end of the external protective tube 56 is 30 mm, and the distance S from the lower end of the solid electrolyte tube 54 to the lower end of the external protective tube is 5 mm. did.

Slits having the width and the number shown in Table 1 below were formed in the above-mentioned oxygen measuring probe, the reinforcing member was attached or detached, and the measuring portion was immersed in the molten metal.

In the oxygen measuring probe according to the present embodiment, 1/5 and 1/4 of the outer diameter of the solid electrolyte tube 54.
Are 2.0 mm and 2.5 mm respectively, and the external protection tube 5
1/3 and 3/5 of the outer diameter of 6 are 8.33 mm and 1 respectively
It is 5.00 m.

[0051]

[Table 1]

Table 2 below shows the results obtained by immersing the oxygen measuring probe having the slit shown in Table 1 above in the molten metal.

The measurement accuracy is as follows: Vacuum Sample (V.
Accuracy based on the analysis value of S), σ% (variation coefficient) = ± 3% or less, σ% = ± 4% or less, σ% = ± 5
% Or less and σ% = ± 5% or more, respectively, "◎"
(Excellent), "○" (good), "△" (somewhat bad) and "x"
The results are shown in Table 2 below as (defective).

The durability column of Table 2 below shows the results of analysis of the time that was actually measurable.
Durability of more than 30 hours, 10 to 30 hours, and less than 10 hours are "○" (good) and "△", respectively.
Shown as (OK) and “X” (NO).

[0055]

[Table 2]

As shown in Table 2 above, for Examples Nos. 1 to 3 and 4 to 7 having slit widths within the scope of the claims, Example No. 1 having a narrow slit width and Example Nos. 3 and 7 having a large slit width. In all cases, the measurement accuracy and durability were excellent, except that the measurement accuracy or durability was slightly inferior.

On the other hand, in Comparative Examples Nos. 1 and 3, since the width of the formed slit is smaller than the claimed range,
The measurement accuracy was lower than that of each example. Also,
In Comparative Examples Nos. 2 and 4, since the width of the formed slit was larger than the scope of the claims, the tip of the external protection tube was deformed and measurement was impossible, or the solid electrolyte tube was broken due to the deformation. .

Second Embodiment FIG. 8 is a cross-sectional view showing a measuring section constructed by using an internal protective tube 65 in the oxygen measuring probe according to the present embodiment. As shown in FIG. 8, a solid electrolyte tube 64 having a closed lower end is arranged in the center of the measuring section, and the tip of the sheath thermocouple 62 is inserted into the solid electrolyte tube 64. There is. Further, the solid electrolyte tube 64 has M
A reference substance 63 made of, for example, o and MoO ₂ is filled. Then, the upper end of the solid electrolyte tube 64 is fitted and fixed by a fixing agent to the upper end of the solid electrolyte tube 64 and the lower end of the inner protective tube 65 that covers the sheath thermocouple 62 not inserted into the solid electrolyte tube 64. ing. In addition, a slit 67 is formed at the lower end of the external protection tube 66,
A reinforcing body 61 is attached to the lower end surface of the member 6.

The outer and inner diameters of the solid electrolyte tube 64 were 8 mm and 6 mm, respectively, and the outer and inner diameters of the outer protective tube 66 were 21.7 mm and 16 mm, respectively. Also, from the lower end of the solid electrolyte tube 64 to the external protection tube 66.
The measuring unit of the oxygen measuring probe was configured with the distance S to the lower end of 8 mm being 8 mm.

Slits having the width and the number shown in Table 3 below were formed in the above-mentioned oxygen measuring probe, the reinforcing member was attached or detached, and the measuring portion was immersed in the molten metal.

In the oxygen measuring probe according to the present embodiment, 1/5 and 1/4 of the outer diameter of the solid electrolyte tube 64.
Are 1.6 mm and 2.0 mm respectively, and the external protection tube 6
1/3 and 3/5 of the outer diameter of 6 are 7.23 mm and 1 respectively
It is 3.02 mm.

[0062]

[Table 3]

Table 4 below shows the results obtained by immersing the oxygen measuring probe having the slits shown in Table 3 above in the molten metal. The measurement accuracy is the same as in the first embodiment described above.

[0064]

[Table 4]

As shown in Table 4 above, in Example No. 8, the width of the formed slits is within the scope of the claims, but since there is no reinforcing member, the slits are closed and V.I. Although the correlation with S became a little worse, in all the other examples, the results were excellent in measurement accuracy and durability.

On the other hand, Comparative Example No. 5 has no reinforcing member and has a narrow slit width.
The correlation with S is poor, and in Comparative Example No. 6, the width of the formed slit is larger than the claimed range,
The tip of the external protection tube is deformed and the flow of hot water is not stable, and the measurement accuracy changes from good to bad and it is not stable,
In addition, the solid electrolyte tube was broken due to the deformation of the tip of the external protection tube. Further, Comparative Example No. 7 with a reinforcing body
With regard to the above, since the width of the formed slit was smaller than the scope of claims, the measurement and measurement accuracy was lower than that of each example. Furthermore, in Comparative Example 8, since the slit width was too wide, the external protective tube was deformed, resulting in poor durability.

Unlike the first embodiment described above, in this embodiment, the external protective tube and the solid electrolyte tube are not fixed by the fixing agent, so that the external pressure acting on the external protective tube, etc. It was found that various forces rarely act on the solid electrolyte tube via the fixing agent, and have an effect of preventing breakage of the solid electrolyte tube.

[0068]

As described above, according to the present invention,
By forming a predetermined slit or the like at the tip of the protective tube in the oxygen measurement probe, and by setting the ratio of the length of the exposed portion of the solid electrolyte tube in this slit to the length of the slit within a predetermined range, molten metal Even if the protective tube is dipped in the substrate for a long time, it is possible to prevent the distal end portion from being deformed, the slit or the like from being contracted, or being blocked. Therefore, when measuring oxygen in the molten metal using the oxygen measuring probe according to the present invention, it is possible to always contact the fresh molten metal with the solid electrolyte tube, and even after continuous measurement for a long time. Highly accurate and stable measurement can be performed.

Further, by attaching the reinforcing body to the tip end surface of the lower end of the protection tube or in the vicinity of the tip, even if the width of the slit formed in the tip end of the protection tube becomes large, the tip end of the protection tube is directed in the molten metal flow direction. It can be prevented from being deformed, the portion other than the slit of the tip portion being spread in a V shape, being deformed so as to cling to the solid electrolyte tube, the slit being contracted, or being blocked. it can.

Further, by disposing the solid electrolyte tube in the protection tube (external protection tube) by using the inner protection tube, even if a fixing agent is used for fitting the inner protection tube and the solid electrolyte tube,
Since this fitting part is located further above the upper end of the slit formed in the external protection tube, the measurement accuracy may be reduced due to mixing of the fixative into the molten metal during measurement, and as a result, the product accuracy Can be prevented from decreasing.

Furthermore, by installing a predetermined oxygen continuous measuring device in the product manufacturing line using the molten metal, labor saving in operation can be achieved and stable operation can be realized. In addition, since the required oxygen activity and temperature information is accurately displayed on each manufacturing line, it is possible to manufacture high quality and highly accurate products.

[Brief description of drawings]

FIG. 1 is a sectional view showing an oxygen continuous measurement probe according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing a sensor unit of the probe.

FIG. 3 is a cross-sectional view showing a sensor portion of the probe in which a reinforcing body is attached to the tip of the probe.

FIG. 4 is a view showing a probe front end surface to which a reinforcing member is attached.

[Fig. 5] Fig. 5 shows the product activity on the horizontal axis and the measured oxygen activity on the vertical axis. When the Kubaschewski value is used as Pref, the measured oxygen activity in the molten metal and the product activity are shown. It is a graph which shows the relationship of.

FIG. 6 is a schematic configuration diagram showing an oxygen continuous measuring apparatus according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view showing an example of a measurement unit of the oxygen measurement probe according to the embodiment of the present invention.

FIG. 8 is a cross-sectional view showing an example of a measurement unit of the oxygen measurement probe according to the embodiment of the present invention.

FIG. 9 is a schematic cross-sectional view showing a conventional oxygen measuring probe.

FIG. 10 is a schematic cross-sectional view showing a conventional oxygen measuring probe.

FIG. 11 is a view showing an external protection tube of the probe,
(A) is a side view in which a slit is formed at the measurement side tip,
(B) is a side view in which a through hole is formed, and (c) is a bottom view of the external protection tube shown in (a).

[Explanation of symbols]

 1,41; Oxygen measurement probe 2, 52, 62; Sheath thermocouple 3, 53, 63; Reference substance 4, 54, 64; Solid electrolyte tube 5, 65; Internal protection tube 6, 56, 66, 71; External Protective tube 7a, 7b, 57, 67, 77; Slit 8; Socket 9; Terminal block 10; Terminal box 11; Measuring part 31, 51, 61; Reinforcement body 42; Fixing means 43; Gutter 44, 75; Molten metal 45 Computing device 46; first display device 47; second display device 48; third display device 72; fixative 73; solid electrolyte tube 74; lead wire 76; residual gas 78; through hole 79; voltmeter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hatsushi Yamashita 1-5-1 Kiba, Koto-ku, Tokyo Inside Fujikura Ltd. (72) Inventor Hisao Igawa 1-7-10 Nishihonmachi, Nishi-ku, Osaka City, Osaka Prefecture Kawaso Electric Industry Co., Ltd. (72) Inventor Yukio Kanagawa 1-7-10 Nishihonmachi, Nishi-ku, Osaka City, Osaka Prefecture Kawaso Electric Industry Co., Ltd.

Claims (7)

[Claims] 1. A solid electrolyte tube of one-end closed type, a sheath thermocouple inserted into the solid electrolyte tube and also serving as an internal electrode, a reference substance filled in the solid electrolyte tube, and externally fitted to the solid electrolyte tube. A slit having a protective tube also serving as an external electrode, the width or diameter of which is 1/4 or more of the outer diameter of the solid electrolyte tube and less than 1/3 of the outer diameter of the protective tube at the tip of the protective tube, or A probe for continuously measuring oxygen in a molten metal, wherein a plurality of through holes are formed. 2. A solid electrolyte tube of one-end closed type, a sheath thermocouple inserted into the solid electrolyte tube and also serving as an internal electrode, a reference material filled in the solid electrolyte tube, and externally fitted to the solid electrolyte tube. A protective tube that also serves as an external electrode; and a reinforcing member attached to the tip of the protective tube. The width or diameter of the protective tube is 1/5 or more of the outer diameter of the solid electrolyte tube. A probe for continuously measuring oxygen in molten metal, characterized in that a plurality of slits or through holes having a diameter of less than 3/5 of the outer diameter of the protective tube are formed. 3. The slit has a ratio of a length of the solid electrolyte tube exposed in the slit to a length of the slit of 1: 7 to 6: 7. Or a probe for continuously measuring oxygen in the molten metal according to 2. 4. Inside the protection tube, there is an internal protection tube that covers the upper end of the solid electrolyte tube and the sheath thermocouple of the part led out from the solid electrolyte tube. The oxygen continuous measurement probe in molten metal according to any one of claims 1 to 3, wherein the probe is fitted and fixed at the lower end to the upper end of the solid electrolyte tube. 5. The reinforcing member is a rod-shaped or plate-shaped member bridging the slit at one or a plurality of positions at the tip of the protective tube having the slit formed therein. 5. A probe for continuous measurement of oxygen in molten metal according to any one of 4 to 4. 6. The reinforcing body comprises a ring-shaped member,
The probe for continuously measuring oxygen in molten metal according to claim 2, wherein the reinforcing body is fitted and fixed to a tip portion of the protective tube. 7. A probe for continuously measuring oxygen in molten metal according to any one of claims 1 to 6, and an electromotive force and a temperature signal measured by the probe to determine the oxygen activity and the temperature of the molten metal. Any one of the calculation processing means to be obtained, the first display means for displaying the oxygen activity and the temperature of the molten metal obtained by the calculation processing means over time, or the second display means for displaying only the oxygen activity. An apparatus for continuously measuring oxygen in molten metal, comprising: