JP3073926B2 - Probe and measuring device for continuous measurement of oxygen in molten metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe for continuously measuring oxygen in molten metal and a measuring apparatus capable of continuously measuring the amount of oxygen in molten metal such as molten copper for a long time. TECHNICAL FIELD The present invention relates to a probe and a measuring device for continuous measurement of oxygen in molten metal which are suitable when the measurement is performed.

[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 a molten metal.
As shown in FIG. 9, in the conventional probe for oxygen measurement, a solid electrolyte tube 73 whose one end is closed at the center is arranged, and a platinum wire is inserted inside the lower end closed at the solid electrolyte tube 73. And the like are connected. In addition, an outer protective tube 71 serving as an external electrode is provided on the outer peripheral portion of the solid electrolyte tube 73 to protect the solid electrolyte tube 73 and a lower part of the solid electrolyte tube 73 is a fixing agent 72 made of refractory cement or the like. External protection tube 7
It is fixed in 1. And one end is a solid electrolyte tube 7
A voltmeter 79 is connected between the other end of the lead wire 74 connected to the inner lower end of the third and the upper end of the external protection tube 71.

In the oxygen measuring probe thus constructed, 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. Meanwhile, when the measuring portion formed at the lower end of the oxygen measuring probe is immersed in the molten metal 75, an oxygen concentration cell having the standard gas as the reference electrode having a known oxygen partial pressure is formed, and the inside and outside of the solid electrolyte tube 73 are formed. 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.

In the case of measuring molten copper containing almost no impurities, when the lower end of the oxygen measurement probe shown in FIG. 9 is immersed in the molten copper, the fixing agent 72 comes into contact with the molten copper 75 and the measurement is performed. Over a long period of time, the fixing agent 72 reacts with the molten copper to affect the electromotive force, and at the same time, the fixing agent 72 is mixed into the molten copper 75, thereby deteriorating the properties of the product manufactured from the molten copper 75. Would.

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

In Japanese Utility Model Publication No. 2-40536,
An oxygen measurement probe is disclosed in which a melt filter having cells such as slits is provided on the outer peripheral surface at the lower end of an 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 disadvantages.

That is, when the size of the slit 77 or the through hole 78 is formed smaller than the size of the external protection tube 71 and the solid electrolyte tube 73, the molten metal may be removed from the external protection 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 the molten metal and the molten metal outside the external protection tube 71 cannot be circulated smoothly. .

Normally, the molten metal in the molten metal bath is not in a uniform component state. Therefore, 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 that fresh molten metal, that is, molten metal that has not yet contacted the solid electrolyte tube 73, can always contact the solid electrolyte tube 73.

On the other hand, when the size of the slit 77 or the like is formed larger than the size of the external protection tube 71 or the like, the molten metal flows into and out of the external protection tube 71 smoothly. However, when a large amount of molten metal flows into the inside of the external protection tube 71, the space 76 for allowing gas to remain inside the external protection tube 71 cannot be maintained, and the fixing agent 72 Contact.

Also, depending on the width 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 outer protective tube 71 where the slit is not formed is bent inward due to the pressure due to the flow of the molten metal, and contacts the solid electrolyte tube 73. 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 having a too small width of the slit 77 is used continuously for a long time, the lower end of the external protective tube 71 shrinks and the slit 77 is closed.

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 used over this time, clogging of the filter and the like will occur, so that the molten metal cannot be stably brought into contact with the solid electrolyte tube.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a probe for continuous measurement of oxygen in a molten metal capable of performing highly accurate and stable measurement even when used for a long time. It is intended to provide a device.

[0014]

According to the present invention, there is provided a probe for continuous measurement of oxygen in a molten metal according to the present invention, comprising: a solid electrolyte tube having a closed end; 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, an external protection tube serving also as an external electrode externally fitted to the solid electrolyte tube, and provided inside the external protection tube;
The top end of the solid electrolyte tube and the solid electrolyte tube
Cover the sheathed thermocouple at the lower end, and
Internal protective tube fitted and fixed to the upper end of the solid electrolyte tube
If has, at the distal end of the outer protective tube, the width or diameter is the solid electrolyte tube more than 1/4 of the outer diameter of the longitudinal external protective pipe is less than 1/3 of the outer diameter of the outer protective tube A plurality of slits or through holes extending in the direction are formed.

Further, the mounting of the reinforcement to the front end portion of the outer protective tube, the the distal end of the outer protective tube, the width or diameter less than 1/5 of the outer diameter of the solid electrolyte tube, outside the outer protective tube A plurality of slits or through holes having a diameter of less than 3/5 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 in a range of 1: 7 to 6: 7.
No.

Further, 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 external protective tube having the slit formed therein. It is preferable that the reinforcing member is formed of a ring-shaped member, and the reinforcing member is fitted and fixed to a distal end portion of the external protection tube.

[0018] The apparatus for continuously measuring oxygen in molten metal according to the present invention comprises:
An arithmetic processing means 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 with time, second display means for displaying only the oxygen activity, and intermittent measurement at regular time intervals And a third display means for displaying the oxygen activity and the temperature of the molten metal obtained by the arithmetic processing means from the generated electromotive force and temperature signal.

[0019]

In oxygen continuous measurement probe according to the present invention, since a slit or through hole of a predetermined shape at the distal end of the outer protective pipe is formed in plural in the measurement portion, the outer
And out of the molten metal parts protective tube smoothly it can be lubricated, always fresh molten metal can be contacted with the solid electrolyte tube. The upper end of the solid electrolyte tube is protected internally.
By fitting and fixing to the lower end of the tube, the solid electrolyte tube
Since it can be held without contacting the inner surface of the external protection tube,
External force from the external protective tube may act on the body electrolyte tube.
And breakage of the solid electrolyte tube
Can be prevented. Therefore , the oxygen concentration in the molten metal can be measured with high accuracy.

Further, by attaching a reinforcing member to the distal end of the outer protective tube, the range of shapes and sizes of slits and 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.

[0022]

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

The width of the slit and the diameter of the through hole The width of the slit and the size of the diameter of the through hole formed at the tip of the external protective tube greatly affect the measurement accuracy.
That is, if fresh molten metal is always brought into contact with the solid electrolyte tube at the time of measurement, the measurement can be performed with high accuracy. Therefore, it is necessary to form a slit or the like having a predetermined size or more, also the shapes of the slits is too small, there is a possibility that slits or the like during the measurement by the slag or the like clogged. In order to supply such fresh molten metal and prevent slit blockage, it is necessary that the width of the slit and the diameter of the through hole be at least １ ／ of the outer diameter of the solid electrolyte tube.

The width of the slit and the size of the diameter of the through-hole also affect the strength of the external 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 external protection tube where the slit is not formed becomes small, and this portion is measured. It is easily deformed at times. In order to prevent such deformation of the outer protective tube, the width of the slit and the diameter of the through hole must be adjusted.
It is necessary to be less than 1/3 of the outer diameter of the part protective tube.

[0026] Therefore, the diameter of the width or the through hole of the slit formed in the front end portion of the outer protective tube, any more than 1/4 of the outer diameter of the solid electrolyte tube, less than one third of the outer diameter of the outer protective tube And

In the case where the shape of the slit or the like is made larger than the above-mentioned range or smaller than the above-mentioned range, it is effective to attach a reinforcing member to the tip of the external protection tube. As the reinforcing member, for example, a rod-shaped or plate-shaped member that connects a portion where the slit is not formed at the distal end portion of the outer protective tube in a bridging manner, or a band-shaped ring or the like may be used. Good. 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 outer protective tube is reduced to 1/5 of the outer diameter of the solid electrolyte tube.
Above, it may be less than 3/5 of the outer diameter of the outer protective tube.

Exposure of solid charge tube 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 external protection tube has an influence on the measurement accuracy and the protection of the solid electrolyte tube. That is, if the measurement portion of the oxygen measurement probe is configured such that the exposed portion of the solid electrolyte tube is small, or the lower end of the solid electrolyte tube is positioned above the upper end of the slit, the measurement portion is not measured. Even when immersed in molten metal, the molten metal may not be able to come into contact with the solid electrolyte tube, and the measurement accuracy is reduced. Therefore, it is preferable that the ratio of the length of the exposed portion of the solid electrolyte tube to the length of the slit is 1: 7 or more. Conversely, if the exposed part 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 external protective tube, the solid electrolyte tube may be damaged when handling the oxygen measurement probe. In some cases. Therefore, the length of the exposed portion of the solid electrolyte tube is preferably shorter than the length of the slit, and the ratio is preferably 6: 7 or less.

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

In the continuous oxygen 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 section 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 means at appropriate times. By installing this oxygen continuous measurement device at one or more locations on the production line for products made of molten metal, necessary oxygen value and temperature information can be obtained accurately, so that high-quality and high-precision Products can be manufactured.

[0031]

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

In the measuring section 11, a solid electrolyte tube 4 whose lower end is closed is disposed at the center, and the tip of the sheath thermocouple 2 also serving as an internal electrode is inserted into the solid electrolyte tube 4. I have. The solid electrolyte tube 4 is filled with a reference material 3 made of Mo, MoO2, or the like. The sheath thermocouple 2 at the upper end of the solid electrolyte tube 4 and the portion led out from the solid electrolyte tube 4 is fitted by an inner protective tube 5, and the lower end of the inner protective tube 5 is fitted to the solid electrolyte tube 4. Are fitted together, and both are fixed by a fixing agent such as refractory cement. An external protective tube 6 also serving as an external electrode is externally fitted to the internal protective tube 5 and the fixed electrolyte tube 4. A slit 7a extending in the axial direction of the external protective tube 6 is provided at the lower end of the external protective tube 6. 7b is formed. On the other hand, in the terminal portion, a terminal box 10 provided with a lid is provided.
Inside, a terminal block 9 having an output terminal or the like to the outside is installed, and a socket 8 is screwed to the bottom of the terminal box 10.
An upper end of the outer protective tube 6 is screwed to a lower portion of the socket 8, and an upper end of the inner protective tube 5 is fixed with cement or the like. Further, the upper part of the sheath thermocouple passes through the socket 8 and the terminal block 9, and the tip is wired to a predetermined terminal.

When the oxygen amount of the molten metal is measured by the oxygen measuring probe thus configured, first, the measuring section 11 is directed downward, and its tip is immersed in the molten metal. Then, an oxygen concentration cell having the sheath thermocouple 2 as a reference electrode is formed, and 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 are formed. An electromotive force is generated. The generated electromotive force is led out to the upper terminal via the sheath thermocouple 2 in contact with the reference substance 3 and the external protective tube 6 in contact with the molten metal, and is detected at this terminal.

In the measuring section of the probe for oxygen measurement according to the present embodiment, the solid electrolyte tube is not fixed directly in the outer protective tube as in the prior art, but is connected to the lower end of the inner protective tube 5 by the solid electrolyte tube 4. 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 fixed. It is held without touching.
For this reason, there is no possibility that the refractory cement is mixed into the molten metal during the measurement, and the molten metal can be brought into sufficient contact with the outer peripheral surface of the solid electrolyte tube. Can be measured. Further, during the measurement, since the external pressure due to the distortion of the external protective tube 6 does not act on the solid electrolyte tube, the solid electrolyte tube 4 is broken or the thermocouple wire is disconnected due to the distortion of the solid electrolyte tube. Can be prevented.

Further, slits 7a and 7b of a predetermined shape are formed at the lower end of the outer protective tube 6. That is, the width of the formed slits 7 a and 7 b is equal to or more than ４ of the outer diameter of the solid electrolyte tube 4, and is equal to 1 of the outer diameter of the outer protective tube 6.
By setting the ratio to 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 always be brought into circulating contact with the outer surface of the solid electrolyte tube 4.

Next, as a second embodiment, the external protective tube 6
An oxygen measurement probe having a reinforcing member attached to the lower end of the probe will be described. FIG. 3 is a side view illustrating an example of a sensor unit in which a reinforcing member is attached to a measurement unit of the oxygen measurement probe.
(A) shows the case where the reinforcing member is attached to the lower end surface of the external protective tube, and (b) shows the case where the reinforcing member is attached near the lower end of the external protective tube. FIG. 4 is a bottom view of the oxygen measurement 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 outer protective tube needs to have a predetermined width to prevent the lower end of the outer protective tube from being broken during measurement. When it is necessary to increase the size of the outer protective tube 6 as shown in FIGS. 3 (a) and 4 (a) to 4 (d), no slits 7a and 7b are formed. , A reinforcing member 31 made of a bar or a plate is attached so as to bridge a plurality of locations.

The reinforcing member is not only a member attached to the lower end surface of the outer protective tube 6 but also a member into which the distal end of the lower end of the outer protective tube 6 is inserted as in a reinforcing member 32 formed of a band-like ring. Is also good. Further, a plurality of such reinforcements 32 may be fitted into the lower end of the external reinforcement 6.

The reinforcing member is not limited to the above-described reinforcing members 31 and 32. The reinforcing member is not limited to the external protective tube while ensuring the flow of the molten metal so that fresh molten metal always contacts the solid electrolyte tube. Any material can be used as long as it can prevent the lower end portion from being deformed or the slit from contracting and closing.

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

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

[0042]

[Number 1] ^{_{a o = exp [-ΔG o /}} RT] · [(Pθ 1/4 + P ref 1/4) exp [-E
^{F / RT] -Pθ 1/4] 2} a o: molten copper in oxygen activity E: electromotive force T: absolute temperature R: gas constant F: Faraday constant Pshita: oxygen partial pressure Pref which ionic conductivity and electronic conductivity are equal : Equilibrium oxygen partial pressure of reference material ΔG ^o : Free energy change due to dissolution in molten copper

Pref in the above equation (1) represents the equilibrium oxygen partial pressure of the reference substance, and FIG.
FIG. 8 is a graph showing the correlation between the oxygen activity calculated using the value of aschewski on the vertical axis and the product analysis value on the horizontal axis. As shown in FIG.
When Kubaschewski's value was used as f, the product analysis value and the oxygen activity agreed best. For this reason, it is preferable to use the value of Kubaschewski as Pref.

The arithmetic processing unit 45 outputs these arithmetic values to the display units 46, 47, and 48 for display. The first display 46 displays the calculated oxygen value and the temperature, the second display 47 displays only the calculated oxygen value, and the third display 48 displays the electromotive force measured intermittently at regular intervals. And the oxygen activity and the temperature of the molten metal determined by the processing unit 45 from the temperature signal.

By installing one or a plurality of the continuous oxygen measuring devices constructed as described above on a production line of a product made of molten metal, labor saving in operation can be achieved and stable operation can be achieved. Can be realized. Further, in each production line, necessary oxygen value and temperature information are accurately displayed, so that high-quality and high-accuracy products can be produced.

Next, the result of actually measuring the oxygen of the molten metal by 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 section of the probe for oxygen measurement according to the present embodiment which is constructed without using an internal protective tube. As shown in FIG. 7, a solid electrolyte tube 54 having a closed lower end is disposed at the center of the measurement unit, and the distal end of the sheath thermocouple 52 is inserted into the solid electrolyte tube 54. I have. The solid electrolyte tube 54 contains M
A reference material 53 made of o, MoO2, or the like is filled. The solid electrolyte tube 54 is fixed in the external protection tube 56 by a fixing agent 58 such as refractory cement.
A slit 57 is formed at the lower end of the external protection tube 56, and the reinforcing member 51 is attached to the lower end surface of the external protection tube 56.

The outer diameter and the inner diameter of the solid electrolyte tube 54 were 10 mm and 6 mm, respectively, and the outer diameter and the inner diameter of the outer protective tube 56 were 25 mm and 21 mm, respectively. Further, the distance T from the lower end of the fixing agent 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.

A slit having the width and the number shown in Table 1 below was formed in the probe for oxygen measurement as described above, and a reinforcing member was attached or detached, and the measuring portion was immersed in the molten metal.

In the probe for oxygen measurement according to the present embodiment, １ ／ and の of the outer diameter of the solid electrolyte tube 54 are used.
Are 2.0 mm and 2.5 mm, respectively.
One-third and three-fifths of the outer diameter of 6 are 8.33 mm and 1 respectively.
5.00 mm .

[0051]

[Table 1]

The results of immersing the oxygen measuring probe having the slits shown in Table 1 above in the molten metal are shown in Table 2 below.

Note that the measurement accuracy was measured using Vacuum Sample (V.
The accuracy is based on the analysis value of S), σ% (coefficient of variation) = ± 3% or less, σ% = ± 4% or less, σ% = ± 5
% Or less when σ% = more than ± 5%.
(Excellent), "○" (good), "△" (somewhat bad) and "x"
It is shown in Table 2 below as (defective).

The column of durability in Table 2 below shows the results of analysis of the time that was actually measurable.
When the durability exceeds 30 hours, when the durability is 10 to 30 hours, and when the durability is shorter than 10 hours, “○” (good), “△”
(Acceptable) and "x" (impossible).

[0055]

[Table 2]

As shown in Table 2, with respect to Examples Nos. 1 to 3 and 4 to 7 in which the slit width falls within the scope of the claims, Examples No. 1 having a narrow slit width and Examples Nos. 3 and 7 having a wide slit width. In each case, 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, the width of the formed slit is smaller than the scope of the claims.
The measurement accuracy was lower than in 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 protective tube was deformed, making measurement impossible, or the solid electrolyte tube was broken by the deformation. .

Second Embodiment FIG. 8 is a cross-sectional view showing a measuring section formed by using an internal protective tube 65 in an oxygen measuring probe according to the present embodiment. As shown in FIG. 8, a solid electrolyte tube 64 having a closed lower end is disposed at the center of the measurement unit, and the distal end of the sheath thermocouple 62 is inserted into the solid electrolyte tube 64. I have. The solid electrolyte tube 64 has M
A reference material 63 made of o, MoO ₂ or the like is filled. 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 covering the sheath thermocouple 62 not inserted into the solid electrolyte tube 64. ing. Further, a slit 67 is formed at the lower end of the external protection tube 66 so that the external protection tube 6
A reinforcement body 61 is attached to a lower end surface of the sixth member 6.

The outer diameter and the inner diameter of the solid electrolyte tube 64 were 8 mm and 6 mm, respectively, and the outer diameter and the inner diameter of the outer protective tube 66 were 21.7 mm and 16 mm, respectively. Further, an outer protective tube 66 is connected from the lower end of the solid electrolyte tube 64 to the outer protective tube 66.
The distance S to the lower end of the probe was set to 8 mm to constitute a measurement unit of the oxygen measurement probe.

A slit having the width and the number shown in Table 3 below was formed in the oxygen measuring probe as described above, and a 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 used.
Are 1.6 mm and 2.0 mm, respectively.
1/3 and 3/5 of the outer diameter of 6 are 7.23 mm and 1 respectively.
3.02 mm.

[0062]

[Table 3]

The results of immersing the oxygen measuring probe having the slits shown in Table 3 above in the molten metal are shown in Table 4 below. 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 slit was within the scope of the claims. However, since there was no reinforcing member, the slit was closed, and V.V. Although the correlation with S was slightly deteriorated, the other examples resulted in excellent measurement accuracy and durability.

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

Note that, unlike the first embodiment described above, in this embodiment, the external protection tube and the solid electrolyte tube are not fixed with a fixing agent. It has been found that various forces hardly 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 external protective tube in the oxygen measurement probe, and by setting the ratio between the length of the exposed portion of the solid electrolyte tube and the length of the slit in this slit to be within a predetermined range, Even if the external protective tube is immersed in the molten metal for a long time, it is possible to prevent the tip portion from being deformed, the slit or the like from contracting or closing, and the like. Also, use a solid electrolyte
By placing the tube inside the outer protection tube, the inner protection tube
Even if a fixing agent is used to fit the solid electrolyte tube,
Part is higher than the upper end of the slit formed in the external protection tube.
Fixation agent is mixed into the molten metal during measurement
May reduce measurement accuracy and, as a result,
It is possible to prevent the occurrence of defective products.
For this reason, when measuring the oxygen in the molten metal using the oxygen probe according to the present invention, it is possible to always contact fresh molten metal to the solid electrolyte, even if continuous measurement for a long time, Highly accurate and stable measurement can be performed.

[0069] Further, by attaching a reinforcing member to the lower end tip surface or the vicinity of the distal end of the outer protective tube, even if the width of the slit formed in the front end portion of the outer protective tube becomes large, the external coercive <br/> Mamorukan The tip of the tip deforms in the flow direction of the molten metal, the portion other than the slit of the tip expands in a C-shape, deforms so as to embrace the solid electrolyte tube, the slit contracts, or is closed. Can be prevented.

[0070]

[0071] Further, in the product manufacturing line using a molten metal, by placing a predetermined oxygen continuous measurement apparatus, it is possible to save labor on operation, it is possible to realize a stable operation of. In each production line,
Since the necessary oxygen activity and temperature information are accurately displayed, a high-quality and high-precision product can be manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a probe for continuous oxygen measurement 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 sectional view showing a sensor section of the probe in which a reinforcing member is attached to a tip of the probe.

FIG. 4 is a diagram showing a probe tip surface to which a reinforcing member is attached.

FIG. 5 shows the product analysis value on the horizontal axis, the measured oxygen activity on the vertical axis, and the measured oxygen activity value and the product analysis value in the molten metal when the value of Kubaschewski is used as Pref. It is a graph which shows the relationship of.

FIG. 6 is a schematic configuration diagram showing an oxygen continuous measurement device according to an example of the present invention.

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

FIG. 8 is a cross-sectional view showing one example of a measuring unit of the oximetry probe according to the embodiment of the present invention.

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

FIG. 10 is a schematic sectional view showing a conventional oxygen measurement 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 tip on the measurement side,
(B) is a side view in which a through hole was 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 material 4, 54, 64; solid electrolyte tube 5, 65; internal protective tube 6, 56, 66, 71; Protection tube 7a, 7b, 57, 67, 77; Slit 8; Socket 9; Terminal block 10; Terminal box 11; Measuring unit 31, 51, 61; Arithmetic processing unit 46; first display unit 47; second display unit 48; third display unit 72; fixing agent 73; solid electrolyte tube 74; lead wire 76; residual gas 78; through hole 79;

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yamashita Hatsu 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (72) Inventor Hisao Igawa 1-7-10 Nishihonmachi, Nishi-ku, Osaka-shi, Osaka Inside So Electric Industry Co., Ltd. (72) Inventor Yukio Kanakawa 1-7-10 Nishihonmachi, Nishi-ku, Osaka City, Osaka Prefecture Inside Kawaso Electric Industry Co., Ltd. (56) References JP-A-55-98351 (JP, A) JP-A-61-260156 (JP, A) JP-A-63-191056 (JP, A) JP-A-58-154461 (JP, U) JP-A-58-178668 (JP, U) JP-A-61-199667 (JP, U) Japanese Utility Model 57-42947 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 27/411 G01N 33/20

Claims (6)

(57) [Claims] 1. A solid electrolyte tube closed at one end, 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. An external protection tube also serving as an external electrode, and the solid electrolyte tube provided inside the external protection tube.
In front of the upper end of the pipe and the part derived from the solid electrolyte tube
Cover the sheath thermocouple, and at the lower end thereof, the solid electrolyte
Has an inner protective tube which is fitted and fixed to the upper end of the tube, and the distal end of the outer protective tube, less than 1/4 the width or diameter of the outer diameter of the solid electrolyte tube, outside the outer protective pipe A probe for continuous measurement of oxygen in molten metal, wherein a plurality of slits or through holes extending in the longitudinal direction of the outer protective tube having a diameter of less than 1/3 are formed. 2. A solid electrolyte tube which is closed at one end, a sheath electrode 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. An external protection tube also serving as an external electrode, and a reinforcing body attached to a tip of the external protection tube,
On the solid electrolyte tube provided inside the external protection tube
The end portion and the portion of the solid electrolyte tube,
At the lower end of the solid electrolyte tube.
It has an inner protective tube which is fitted and fixed to an upper end portion, the outer
A slit or through hole extending in the longitudinal direction of the external protective tube having a width or a diameter of 1/5 or more of the outer diameter of the solid electrolyte tube and less than 3/5 of the external diameter of the external protective tube at the tip of the partial protective tube. A probe for continuous measurement of oxygen in a molten metal, wherein a plurality of are formed. 3. The slit according to claim 1, wherein a ratio of a length of the solid electrolyte tube exposed in the slit to a length of the slit is 1: 7 to 6: 7. Or the probe for continuous measurement of oxygen in molten metal according to 2. 4. The bar according to claim 1, wherein the reinforcing member is a bar-shaped or plate-shaped member that bridges the slit at one or a plurality of locations at the tip of the external protection tube having the slit. 4. The probe for continuous measurement of oxygen in molten metal according to 2 or 3. 5. The reinforcing member comprises a ring-shaped member,
The probe for continuous measurement of oxygen in molten metal according to claim 2 or 3, wherein the reinforcing body is fitted and fixed to a distal end portion of the external protection tube. 6. A probe for continuous measurement of oxygen in a molten metal according to claim 1, and an oxygen activity and a temperature of the molten metal are measured from an electromotive force and a temperature signal measured by the probe. Any one of a first display means for displaying the oxygen activity and the temperature of the molten metal obtained by the arithmetic processing means with time, or a second display means for displaying only the oxygen activity obtained by the arithmetic processing means An apparatus for continuously measuring oxygen in molten metal, comprising: