JPH10324907A - Integrated probe for molten metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an integrated probe for molten metal which measures temp., activity of component, etc., of the molten metal, e.g. molten steel and at the same time, takes a pin-type sample not contaminated with carbon. SOLUTION: The measuring probe 10 providing a sensor part 4 at the tip and the sampling probe 2 providing a vacuum glass vessel 5 at the tip are fixed with a fixing tool 12 and integrated in a state where they are parallel in contact with each other and parted by 50-200 mm at the tip positions. The vacuum glass vessel 5 is held with a refractory holding part 14 and parted from a paper tube 2 and carbon content contained in the holding part 14 and a protecting cap 15 is regulated. The high accurate sample is obtd. not affected by the paper tube and a paper shell 3 used as the measuring probe and also, without contamination with carbon, even in the case of being an extra-low carbon steel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures the temperature of molten metal such as molten steel and the activity of oxygen, and at the same time,
The present invention relates to a composite probe for collecting a pin-type analysis sample of the molten steel. Hereinafter, the molten metal will be described as an example of the molten metal.

[0002]

2. Description of the Related Art Since the composition of molten steel greatly affects the properties of a product, it is important to quickly and accurately grasp the composition of each molten metal in each refining process and control the operation based on the results. For this reason, the pin type sample for measuring the temperature of molten steel and the activity of components in the steel such as oxygen and analyzing carbon, sulfur and the like is collected.

In the past, these measurements and sampling were performed separately, and the measurement probe for measuring temperature and activity and the sample probe for collecting an analytical sample were independent of each other. However, in recent years, in order to shorten the working time or save the labor, the measurement and the sampling are often performed at the same time, and the composite probe has been used for that purpose.

Conventionally, as a composite probe, one in which a temperature sensor and an electrode united sensor unit and a vacuum glass container for collecting an analysis sample are attached to one long cylinder has been used. One example of this composite probe is shown in FIG. The cylinder 1 forming the outer periphery of the probe comprises a double tube consisting of an inner paper tube 2 and an outer protective tube 6, and the outer protective tube 6 has poor hygroscopicity and does not cause boiling when contacting molten steel. , Or made of alumina-silica refractory. A sensor portion 4 is attached to the tip of the cylinder 1, and the sensor portion 4 is connected to a connector 7 by a lead wire 8 so that a measurement signal can be taken out.

The sensor unit 4 is held by the shell 3 together with the vacuum glass container 5, and a sand mold, a refractory or paper is used for the shell 3. The tip of the vacuum glass container 5 is usually protected by a protective cap 15.
When the tip of this probe faces downward and is immersed in the molten steel sampling position, the protective cap 15 melts, then the tip of the vacuum glass container 5 melts down, and the molten steel enters the container. During this time, the temperature and activity are measured by the sensor,
When the probe is lifted from the molten steel, the molten steel in the vacuum glass container is cooled, and a solid pin-type analysis sample is obtained.

[0006]

However, in the above-mentioned composite probe, carbon may be mixed in the analysis sample although it is a trace amount. This incorporation of carbon is a problem that cannot be ignored in an ultra-low carbon steel having a low carbon content and containing only a few ppm to a few tens of ppm. The cause of carbon contamination is carbon contained in the protective cap and carbonization due to burning of the paper or the cylindrical paper tube forming the shell.

Of these, the use of paper can be eliminated by using a sand mold or refractory for the shell. However, in this case, there is another problem that the cost is increased, and the problem still remains with respect to the cylindrical paper tube and the protective cap.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a composite probe in which carbon contamination and cost increase in an analysis sample are suppressed by the structure and material of the probe. .

[0009]

Means for achieving this object are the following inventions. A first aspect of the invention is a composite probe for molten metal, which is configured by the following members. (A) a long cylindrical measurement probe consisting of a paper tube and a protective tube outside the tube, with a temperature sensor and a sensor for measuring the activity of the molten metal component attached at the tip; The vacuum glass container for collecting the pin type sample for analysis is held by the refractory holding part and stored in the tip part,
A long cylindrical sample probe consisting of a paper tube having a protective cap of a vacuum glass container attached to its tip and a protective tube outside thereof, and (c) the measurement probe and the sample probe, which are arranged in parallel with each other. The tip of the sample probe is in contact with the tip of the measurement probe 50.
Fixture for fixing at a position shifted by a distance of not less than 200 mm and not more than 200 mm.

[0010] The temperature of the molten metal and the activity of the components are measured by a measuring probe equipped with sensors, the content of oxygen and the like in the molten metal are measured, and an analysis sample is collected by a sample probe containing a vacuum glass container. I do. Then, these two probes are arranged in the longitudinal direction, fixed with a fixture, and integrated to form a composite probe. Thereby, measurement and analysis sample collection can be performed by one dipping operation.

The two probes are fixed by shifting the tip of the sample probe by a distance of 50 mm or more and 200 mm or less from the tip of the measuring probe. By shifting the position of the tip, carbon from the paper carbonized at the tip of the measurement probe is prevented from flowing into the vacuum glass container.

If this distance is less than 50 mm, there is a possibility that carbon will be mixed into the sample although it is a trace amount, and even if it exceeds 200 mm, the effect remains the same. On the other hand, if it exceeds 200 mm, it approaches the slag-molten metal interface, so the representativeness of the [C] value is inferior and the frequency of sampling failure due to slag increases.

The reason why the vacuum glass container is held by the holding portion of the refractory material is to avoid using paper in the vicinity of the vacuum glass and to prevent carbon from being mixed into the analysis sample. Alumina, silica, or an alumina-silica refractory is suitable for the refractory of the holding portion.

According to a second aspect of the present invention, there is provided a composite probe for a molten metal, wherein the vacuum glass container is held by the holding portion with its side face wrapped in a sheet of refractory fiber.

The vacuum glass container is held by the holding portion, but is held in a state in which the side surface thereof is wrapped with a sheet of refractory fiber. This is to prevent the vacuum glass container from being broken while the cylinder is broken and taken out of the vacuum glass container in the sample probe. If the vacuum glass container is damaged, the sample may be contaminated by the burned carbonized burnt residue of the paper tube. If the vacuum glass container is wrapped and protected with a sheet of fire-resistant fiber, it will not be damaged, and if it is damaged, the analytical sample will not be contaminated.

According to a third aspect of the present invention, the molten metal is molten steel, the protective cap is a carbon steel having a carbon content of twice or less the carbon content of the molten steel, and an impurity in the sheet and the holding portion. The carbon content is 2 of the carbon content of molten steel.
The composite probe for molten metal described above, wherein the ratio is not more than twice.

The protective cap and the holder are located near the vacuum glass container and are exposed to molten steel, which is a molten metal. Therefore, the amount of carbon contained in the molten steel is regulated. Particularly, since the protective cap is melted, the carbon content of the carbon steel is not more than twice the carbon content of the molten steel. Here, the carbon content of the molten steel is the carbon content after the refining of the molten steel that is the molten metal to be measured. For example, in the case of an ultra-low carbon steel with a carbon content of 0.002 wt%, a protective cap Has a carbon content of 0.0
Use carbon steel of 04wt% or less.

A refractory which does not melt in the holding portion and does not contain carbon as a component is used, but a refractory having a carbon content as an impurity which is not more than twice the carbon content of molten steel is used. Alumina / silica-based refractories such as alumina, mullite and sillimanite can be used for the holding portion.

According to a fourth aspect of the present invention, there is provided a composite probe for molten metal, wherein the fixture is a paper tube or a thin metal tube.

A paper tube or a thin metal tube is used as a fixture for fixing the measurement probe and the sample probe. Since the fixture is used at the rear end of the probe and does not come into direct contact with the molten metal, a thin metal tube can be used. By using a paper tube or a thin metal tube as the fixture, it is possible to easily fix in a short time, for example, nailing can be performed at the time of fixing. The cross-sectional shape of the fixture may be a square whose inner surface circumscribes both probes or a shape in which semicircles at both ends are connected by straight lines.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a composite probe for molten metal according to the present invention, in which a measurement probe 10 and a sample probe 20 are fixed and integrated by hitting a nail 11 on a fixture 12 at the rear end in parallel. The cylinder 1 forming the outer circumference of the measurement probe 10 and the sample probe 20 is a double tube of the inner paper tube 2 and the outer protective tube 6, and the outer protective tube 6 has poor hygroscopicity and is exposed to molten metal. It is made of non-boiling alumina, silica or alumina-silica refractories.

At the tip of the measuring probe 10, a thermometer or a sensor portion 4 such as an electrode for measuring the activity of oxygen or the like of the molten metal is provided.
Are held and attached by the shell 3. The measurement signal from the sensor unit 4 is connected to the connector 7 by the lead wire.
And is taken out from here. An expensive refractory material may be used for the shell 3, but a paper shell can also be used because it is located away from the vacuum glass container 5.

At the tip of the sample probe 20, a vacuum glass container 5 for collecting an analysis sample is attached. The vacuum glass container 5 is held by a holding portion 14 at the tip of the protective tube 6, and the tip of the vacuum glass container 5 is covered with a protective cap 15. The measurement probe 10 and the sample probe 20 are fixed with their tip positions shifted by 50 mm to 200 mm.

FIG. 2 shows the holding state of the vacuum glass container 5 at the tip of the sample probe 20 in detail. A sheet 16 is wound around the side surface of the vacuum glass container 5, and the holding portion 14
, But in order to prevent falling off from the holding part 14,
The vacuum glass container 5 is joined to the holding portion 14 using the joining agent 13. Alumina, silica, or alumina-silica cement containing less carbon is preferably used as the bonding agent.

The holding portion 14 is made of a refractory having a small amount of impurity carbon, such as alumina, silica, or an alumina-silica system. The cylinder 1 only needs to house the vacuum glass container 5 and is thinner than a conventional cylinder that houses the sensor unit 4 and the vacuum glass container 5. For this reason, even if an expensive refractory which does not become a carbon contamination source is used for the holding portion 14, the cost is not significantly affected.

Further, since the holding portion 14 is attached to the outer tube 6, the tip of the paper tube 2 does not come into contact with the molten metal. Even if carbonized, carbon flows into the vacuum glass container 5 together with the molten metal. There is no. Furthermore, since the vacuum glass container 5 is also separated from the tip of the measurement probe 10, even if the shell 3 of the measurement probe 10 is made of paper, it is not affected by it, nor is it affected by the paper tube.

Since the vacuum glass container 5 is hollow, it tends to be pushed by a large force due to the buoyancy of the molten metal having a large specific gravity. Because it is exposed to this force and high temperature,
The cement will be subjected to extremely severe conditions. In order to alleviate this condition as much as possible, the measurement probe 10
When the tip of the sample probe 20 and the tip of the sample probe 20 are displaced, the tip of the sample probe 20 is retracted, and the sample probe 2 is dipped during immersion.
It is better that the tip of 0 is stopped at a shallow position to reduce the buoyancy that the vacuum glass container 5 receives.

FIG. 3 shows a cross section of the fixture 12. It is preferable that the surface of the fixture 12 that comes into contact with the outer tube 6 be as large as possible and have a shape that does not become loose. The one shown in FIG. (A) has a quadrangular cross section, and the one shown in (b) has a shape in which semicircles are connected by straight lines. The former allows easy insertion of two probes and the latter allows a tighter fixation.

[0029]

EXAMPLE Using the composite probe of the present invention, a pin-type sample of a molten steel sample being refined for steel types having different carbon contents was analyzed, and the analytical value of carbon was compared with the analytical value of a lump sample which was simultaneously pumped. I looked it up. Since a large amount of the collected sample is not contaminated in the block sample, a reliable analysis value that accurately represents the molten steel component can be obtained. However, the amount of sample to be used for carbon analysis is about 1 g, and it is necessary to scrape off the chips from the lump sample and use this for carbon analysis.
It takes time to prepare the sample. The pin type sample may be cut into a length of about 10 mm, and it takes almost no time to prepare the sample.

As the composite probe, three kinds of composite probes A, B and C of the present invention and two kinds of comparative example D and conventional example E were used for comparison. A is the tip of the sample probe 70 mm from the tip of the measurement probe, B is 150 mm, and C is 200 mm.
Each is a retreat. D is aligned with the tip of the measurement probe without retracting the tip of the sample probe,
E is a composite probe in which both the conventional sensor unit and the vacuum glass container are attached to one outer cylinder.

FIG. 4 shows the result of the examination. In the figure, the vertical axis is the variation rate of the analytical value of the sample collected by each composite probe with respect to the analytical value of the block sample, and the horizontal axis is the analytical value of the block sample. In addition, the variation rate of the analysis value for each composite probe is represented by A
Denotes a mark, B denotes a mark, C denotes a mark, D denotes a mark, and E denotes a mark. In the example of the invention, the variation rate did not exceed 10%, but in the comparative example D and the conventional example E, the variation rate was 10%.
Was exceeded.

In Comparative Example D and Conventional Example E, the buoyancy due to the molten steel was greater than that of the embodiment of the present invention. Therefore, the vacuum glass container was pushed in and dropped from the holding portion, and a sound and analyzable sample was collected. The frequency of failures did not exceed 50%, whereas that of the examples of the invention did not exceed 10%.

The case where the composite probe for molten metal of the present invention is a composite probe for molten steel has been described above. However, the composite probe of the present invention is not limited to only carbon steel or stainless steel molten steel. This is a composite probe that can be used for molten metal such as metal aluminum.

[0034]

As described above, the composite probe for molten metal according to the present invention is composed of a measuring probe having an outer cylinder of the probe and a sample probe having a vacuum glass container for collecting an analytical sample. It is a composite probe that is separated into books and fixed by integrating the two outer cylinders in parallel with each other with their tips separated by 50 mm or more.

For this reason, even if a paper tube or a low-cost paper shell is used for the measurement probe, there is no carbon contamination due to these at the time of sampling. In addition to this, in the sample probe, the carbon content of the protective cap and the holding part of the vacuum glass container, which may become a source of carbon contamination, is regulated, and further, in order to prevent contamination during cooling sample removal, the vacuum glass container All measures are taken to prevent carbon contamination, such as covering the sides with heat-resistant sheets. In this way, since the collected sample is protected from carbon contamination, even a sample of ultra-low carbon steel can represent the molten steel component with high accuracy without being contaminated, and an accurate analysis value can be obtained. The effect of the present invention for realizing quick and accurate analysis at low cost is great.

[0036]

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a composite probe for molten metal of the present invention.

FIG. 2 is a longitudinal sectional view of a tip portion of a sample probe.

FIG. 3 is a cross-sectional view of the fixture, (a) is a rectangle,
(B) is a shape in which semicircles are connected by a straight line.

FIG. 4 is a graph showing the rate of change of the analysis value of carbon in a pin-type sample collected with a composite probe.

FIG. 5 is a longitudinal sectional view of a conventional composite probe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer cylinder 2 Paper tube 3 Shell 4 Sensor part 5 Vacuum glass container 6 Protective tube 10 Measurement probe 11 Nail 12 Fixture 13 Bonding agent 14 Holding part 15 Protective cap 16 Sheet 20 Sample probe

Continuation of front page (51) Int.Cl. ⁶ Identification code FI G01N 33/20 G01N 33/20 B (72) Inventor Yoshimi Komatsu 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (72 Inventor: Tadashi Mochizuki, 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Inside Nihon Kokan Co., Ltd. (72) Inventor Shigeomi Sato 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Nihon Kokan (72) Invention Person Hirohisa Nakajima 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd. (72) Inventor Keita Iwasaki 3-28-23 Onita, Ichikawa-shi, Chiba

Claims (4)

[Claims] 1. A composite probe for molten metal, comprising: (A) a long cylindrical measuring probe consisting of a paper tube and a protective tube outside thereof, with a temperature sensor and a sensor for measuring the activity of the molten metal component attached to the tip; A vacuum glass container for collecting a pin-type sample for analysis is held in a fire-resistant holding unit and stored at the tip,
(C) the measuring probe and the sample probe, which are arranged in parallel with each other, comprising a paper tube having a protective cap of a vacuum glass container attached at the tip and a protective tube on the outside thereof; The tip of the sample probe is in contact with the tip of the measurement probe 50.
Fixture for fixing at a position shifted by a distance of not less than 200 mm and not more than 200 mm. 2. The composite probe for molten metal according to claim 1, wherein said vacuum glass container is held by said holding portion with its side face wrapped in a sheet of refractory fiber. 3. The molten metal is molten steel, the protective cap is carbon steel having a carbon content not more than twice the carbon content of molten steel, and the content of impurity carbon in the sheet and the holding portion is The composite probe for molten metal according to claim 1 or 2, wherein the carbon content of the molten steel is not more than twice the carbon content. 4. The composite probe for molten metal according to claim 1, 2 or 3, wherein the fixture is a paper tube or a thin metal tube.