JP5061691B2 - Diagnosis method and apparatus for mold thermocouple in continuous casting equipment - Google Patents

Description

  The present invention relates to a mold thermocouple diagnosis method and apparatus for diagnosing normality / abnormality of a mold thermocouple used in a continuous casting facility, more specifically, normality / abnormality of the installation state of the mold thermocouple.

  Continuous casting equipment mold temperature is measured continuously using a thermocouple as a temperature sensor, mainly for the purpose of preventing constraining breakout, monitoring molten steel flow in the mold, and indirectly measuring the molten steel level. Has been. And it is indispensable to stably measure these measurement temperatures for a long period of time in order to achieve the above various purposes.

Thermocouples used in molds for continuous casting equipment need to measure the temperature stably in a poor environment such as high temperature, high humidity, vibration, and a lot of dust. Used.
In addition, if the thermocouple is fixed to the measurement location using welding or adhesive, disconnection or peeling due to vibration is likely to occur, so a mounting structure that mechanically presses the sheath thermocouple against the measurement point with a spring or the like is adopted. There are many.

However, even if the above measures are taken, the thermocouple may become abnormal due to long-term use, and the abnormal temperature cannot be measured normally by the abnormal thermocouple, and the above purpose is achieved. Can not.
Therefore, it is necessary to diagnose the normality / abnormality of the thermocouple, but among the abnormal states of the thermocouple, disconnection can be easily determined by a burnout function or the like.
However, it is not possible to obtain temperature measurement data at all due to disconnection such as measurement error due to sensor individual variation or mounting variation, measurement responsiveness slowdown, measurement accuracy degradation, etc. It is not easy to detect an abnormality of a thermocouple in a state where the above can be obtained, and various studies have been made.

There are the following proposals for diagnosing normality / abnormality of thermocouples in a state where some kind of temperature measurement data is obtained.
(1) A plurality of thermocouples are grouped for each mold attachment site, and the thermocouples are heated with steam or the like in a state where they are attached to the mold, and the electromotive force of each thermocouple is measured and converted into temperature. A method of determining normality / abnormality of a thermocouple by comparing with a predetermined reference value (see Patent Document 1).

(2) Based on temperature measurement data during actual operation, standardize the frequency of temperature changes of thermocouples attached at different positions and compare them with reference values to determine thermocouples with degraded responsiveness , The method of determining that the temperature measurement data is inundated when the average value of the temperature measurement data is within the specified temperature range, and the rate of temperature change and the maximum temperature reached at the start of casting A method of determining a thermocouple having a deteriorated response as compared with (see Patent Document 2).
JP-A-8-159883 JP 2004-314126 A

The one described in Patent Document 1 eliminates individual variations when thermocouples are installed, and repairs and replaces abnormal thermocouples so that the thermocouples are installed in a normal state at the start of mold use. There is an advantage that can be managed in advance.
However, it is difficult to detect on-line that the measurement characteristics gradually deteriorate in an inferior environment such as being used in an operating state.
In addition, there is a problem that a troublesome work such as heating the mold to a high temperature with steam or the like must be performed at the time of installing the thermocouple.

On the other hand, since the thing of patent document 2 is judged based on the online temperature measurement data in operation, the change of the measurement characteristic by the thermocouple installation environment in operation is detected rapidly, and the measure with respect to an abnormal thermocouple There is an advantage that can be done online.
However, since the judgment is based on the measurement data in actual operation, even if there is a change in the temperature measurement characteristic that seems to be abnormal, it is the powder that exists between the molten steel flow in the mold and between the mold and molten steel. It is difficult to clearly determine whether it is caused by operating conditions such as film flow or whether it is caused by deterioration of the thermocouple or thermocouple installation. The problem is that it is difficult to accurately determine whether the thermocouple is normal or abnormal.

Furthermore, since any of the above-mentioned patent documents determines the normality / abnormality of the thermocouple based on the temperature measurement signal of the thermocouple, even if it is determined to be abnormal, it is a malfunction of the thermocouple itself. It is not possible to determine whether it is caused by the deterioration of the installation state of the thermocouple.
For this reason, even if it is determined as abnormal, there is a problem that it is not possible to know whether the subsequent measures, that is, whether the thermocouple itself should be replaced or the thermocouple installation state should be improved.

  The present invention has been made to solve the above-mentioned problems of the prior art, and diagnosis of mold thermocouples in continuous casting equipment that can accurately diagnose normality / abnormality of thermocouples in the same mounting state as the operating state. The object is to obtain a method and a device.

Possible causes for the temperature measurement by the mold thermocouple to be defective include a case where the thermocouple itself becomes abnormal, a case where the thermocouple is installed abnormally, a case where both of these become abnormal, and the like.
As described above, many recent mold thermocouples are mechanically pressed against the mold by a spring or the like and attached.
For this reason, when the thermocouple is mounted from the beginning, there is a variation in the mounting state, or when the pressing failure occurs due to a failure in the pressing means such as a spring, or an oxide film is formed between the tip of the thermocouple and the mold. Thus, there may be a case where the contact state of the mold thermocouple with the mold becomes poor.

The inventor investigated the cause of the poor temperature measurement by the mold thermocouple, and found that among the above-mentioned causes, there are many that are caused by the abnormal contact state between the mold thermocouple and the mold. Obtained.
However, in the past, normality / abnormality of the mold thermocouple was determined based on the temperature measurement signal from the mold thermocouple, and as described above, it was determined whether the mold thermocouple situation was abnormal or the contact state was abnormal. There was a problem that it was not possible to take subsequent measures smoothly.
Therefore, the inventor obtained the idea that if the normality / abnormality of the contact state between the mold thermocouple and the mold can be reliably diagnosed, the cause of temperature measurement abnormality by the mold thermocouple can be accurately determined. It was.

Then, the conventional idea of determining abnormality of the mold thermocouple based on the temperature measurement signal from the mold thermocouple is changed, and instead of being based on the temperature measurement signal from the mold thermocouple, the electricity between the mold thermocouple and the mold is changed. The novel idea of diagnosing the contact state of thermocouples by measuring resistance was obtained. For this purpose, the present invention has been completed by obtaining the knowledge that measurement by simple means is possible by using a grounded sheath thermocouple as the mold thermocouple.
Specifically, the following configuration is provided.

(1) A mold thermocouple diagnosis method according to the present invention is a mold thermocouple diagnosis method for diagnosing normality / abnormality of an installation state of a temperature sensor attached to a mold of a continuous casting facility, and grounding as the temperature sensor. The sheath type thermocouple is attached in a state where it is mechanically pressed to the mold side and is electrically insulated except for the tip of the ground type sheath thermocouple, and the positive terminal of the ground type sheath thermocouple and / or The electrical resistance between the negative terminal and the mold body is measured, and when the measured value is out of a predetermined reference range, the thermocouple is determined to be abnormal.

  In the present invention, the idea that the contact state of the mold thermocouple can be easily diagnosed by measuring the electrical resistance between the mold thermocouple and the mold is obtained. For this purpose, the electrical resistance of the thermocouple temperature measuring unit is simplified. A grounding type sheathed thermocouple that can be measured is used. That is, the idea itself of using a grounded sheath thermocouple as a thermocouple for diagnosing the contact state of the mold thermocouple is novel.

(2) The mold thermocouple normality / abnormality diagnosis apparatus according to the present invention is for diagnosing normality / abnormality of the installation state of the temperature sensor attached to the mold of the continuous casting equipment, A grounded sheath thermocouple attached to the grounded sheath thermocouple, attachment means for attaching the grounded sheath thermocouple in a state of being electrically insulated except for its tip, a positive terminal of the grounded sheath thermocouple, and / or A resistance measuring device that measures the electrical resistance between the negative terminal and the mold body, and a determination unit that determines that the thermocouple is abnormal when the resistance value measured by the resistance measuring device exceeds a preset range. It is characterized by having.

(3) Further, in the mold thermocouple diagnosis apparatus according to (2), a mold temperature management apparatus including a thermocouple temperature converter that inputs a temperature measurement signal of a grounded sheath thermocouple and converts the temperature measurement signal into a temperature. It is provided for diagnosing normality / abnormality of the mold thermocouple, the plus terminal and / or the minus terminal of the grounded sheath thermocouple and the resistance measuring device, the plus terminal of the grounded sheath thermocouple, and A thermocouple signal switching means for switching between the minus terminal and the connection of the thermocouple temperature converter is provided.

In the present invention, the electrical resistance between the positive terminal and / or the negative terminal of the grounding type sheathed thermocouple and the mold body is measured, and the thermocouple is regarded as abnormal when the measured value is out of a predetermined reference range. Since the determination is made, the normality / abnormality determination of each thermocouple when the thermocouple is attached to the mold can be executed safely without being heated and inspected with steam or the like.
In addition, for abnormal thermocouples when an abnormality is discovered, specific measures such as cleaning the mold contact part and thermocouple tip (removing oxide film, etc.), repairing the pressing spring, and exchanging the thermocouple are possible. become.

In addition, even when the mold is mounted on a continuous casting machine and used during operation, the thermocouple can be easily diagnosed without taking the mold off-line for a short time during the stoppage of casting. That determination can be made.
In addition, if the measurement of a thermocouple to be diagnosed is interrupted for a short time even during operation, the thermocouple can be diagnosed by the method of the present invention. In this sense, the diagnosis during operation is also possible. It is.
Furthermore, by managing the measured contact resistance value, it is possible to more clearly determine the temperature change due to operation and the temperature change due to the environment, and it is possible to improve the discrimination accuracy of the abnormal thermocouple.

[Embodiment 1]
FIG. 1 is an explanatory diagram of a normal / abnormal diagnosis method for a mold thermocouple according to an embodiment of the present invention.
FIG. 1 schematically shows a cross section of a part of a mold, and shows a state in which a grounded sheath thermocouple 5 is installed through a backup plate 3 provided on the outer surface side of the mold copper plate 1. Yes.
The normal / abnormal diagnosis method for the mold thermocouple according to the present embodiment is based on the premise that the grounded sheath thermocouple 5 is used as a temperature sensor for measuring the mold temperature.
In the present embodiment, when the grounded sheath thermocouple 5 is expressed, it may be simply referred to as “thermocouple”.

  Here, the grounding type sheathed thermocouple 5 will be described. FIG. 2 is an explanatory diagram of a main part of the grounding type sheathed thermocouple 5. In the sheath thermocouple, a thermocouple wire 13 is placed in a metal sheath, and is filled and sealed with an inorganic insulator such as magnesium oxide and integrated. What is used in the present embodiment is a grounding type, and as shown in FIG. 2, the tip of the strand is joined to a sheath tip 15 made of metal. Some sheathed thermocouples are non-grounded types in which the wire and the tip metal part are not grounded. However, in the present invention, in order to easily diagnose the contact state between the thermocouple and the mold, a grounded sheath is used. A thermocouple 5 is used.

As shown in FIG. 1, the grounding type sheathed thermocouple 5 is installed so as to be pressed against the mold side by a spring 7. Furthermore, the grounding type sheathed thermocouple 5 is attached in a state where the portions other than the tip portion serving as the temperature measuring portion are electrically insulated. Specifically, the grounding type sheathed thermocouple 5 is attached to the backup plate 3 via the insulating member 9, and the grounding type sheathed thermocouple 5 is molded between the outer tube of the grounding type sheathed thermocouple 5 and the insulating member 9. A spring 7 is installed to bias the side.
Then, the resistance value between the plus terminal and the minus terminal of the grounded sheath thermocouple 5 and the mold copper plate 1 is measured by, for example, a tester 11.
When the measured resistance value is out of the predetermined reference value range, it is determined that the thermocouple is abnormal, more precisely, the contact state of the thermocouple is abnormal.

As described above, in the present embodiment, for example, at the time of mold maintenance, the contact resistance value between the thermocouple and the mold is measured as shown in FIG. 1, and the measured value is within a predetermined reference value range. The contact state between the grounding type sheathed thermocouple 5 and the mold is diagnosed.
For example, when the urging force of the spring 7 that presses the grounding type sheathed thermocouple 5 against the mold has decreased over time or for some reason, or when an oxide film such as steam is formed between the tip of the thermocouple and the mold For example, the contact state of the mold thermocouple with the mold deteriorates and the resistance value increases.

When the measured resistance value exceeds the preset reference value range, it is determined that the contact state of the thermocouple is abnormal. Since the resistance value is infinite in the case of a broken wire, the case where the resistance value is not infinite and exceeds a predetermined normal value range is determined as a contact failure.
If it is determined that the contact state is poor, the target thermocouple can be taken out, and specific countermeasures against the contact failure such as replacement of the spring 7 and polishing of the sheath tip 15 can be appropriately taken.
As described above, according to the present embodiment, it is possible to identify a contact failure that frequently occurs even in a thermocouple failure, and therefore it is possible to appropriately take subsequent measures.

  In the first embodiment, the resistance value between the plus and minus terminals of the grounding type sheathed thermocouple 5 and the mold copper plate 1 is measured. However, the plus or minus terminal of the grounding type sheathed thermocouple 5 is measured. The resistance value between any one of the terminals and the copper mold plate 1 may be measured.

In the first embodiment, the resistance value between the positive mold copper plate 1 and the plus terminal and the minus terminal of the grounding type sheathed thermocouple 5 is directly measured on the assumption of the time of maintenance or before operation. did.
However, even if it is not cast, it is difficult to directly measure the resistance value with the mold copper plate 1 in the state of operation. In that case, the resistance value between the mold copper plate 1 and the ground base at the same potential may be measured. Even in this case, there is no problem because the absolute value of the resistance value is not necessary and normal / abnormal is determined based on the resistance value and the relative value in the normal state.

  Further, in the above embodiment, the grounding type sheathed thermocouple 5 is attached via the insulating member 9, but the outer tube of the grounding type sheathed thermocouple 5 is insulated without using the insulating member 9. May be.

[Embodiment 2]
FIG. 3 is an explanatory diagram of Embodiment 2 of the present invention.
The mold thermocouple diagnosis apparatus according to the present embodiment is provided in a mold temperature management apparatus 20 including a thermocouple temperature converter 21 that inputs a temperature measurement signal of the grounded sheath thermocouple 5 and converts the temperature measurement signal into a temperature. The mold thermocouple can be diagnosed online for normality / abnormality.
Therefore, the mold thermocouple diagnosis device according to the present embodiment includes a resistance measurement device 17 that measures the contact resistance between the plus terminal and / or the minus terminal of the grounded sheath thermocouple 5 and the mold 1, and a resistance measurement device. A thermocouple resistance management terminal 19 for determining whether or not the input resistance value is within a range of a predetermined reference value by inputting the measured resistance value, the plus terminal of the grounded sheath thermocouple 5 and / or A thermocouple signal switching board 23 is provided to switch the connection between the minus terminal and the resistance measuring device 17 and the plus terminal and / or the minus terminal of the grounded sheath thermocouple and the thermocouple temperature converter 21.

  The thermocouple resistance management terminal 19 is composed of a personal computer, inputs the measured resistance value of each thermocouple from the resistance measuring device 17, and determines whether or not the input resistance value is within a preset reference value range. It has a function as a judging means for judging. The function as the determination means is realized by a predetermined program stored in the personal computer being executed by the CPU.

The mold temperature management device 20 includes a thermocouple temperature converter 21 that converts an electric signal input from a thermocouple into a measurement temperature, a data collection device 25 that is connected to the thermocouple temperature converter 21 and collects temperature measurement data, and molten steel. Flow data server 27 storing flow data, BO data server 29 storing data related to breakout (BO), flow monitoring terminal 31 for monitoring the flow state of molten steel based on flow data and temperature measurement data, BO data And a BO prediction monitoring terminal 33 for predicting and monitoring the occurrence of BO based on temperature measurement data.
Based on the temperature measurement data, the state of flow of molten steel in the mold and the predictive monitoring of the occurrence of BO are performed.

  In the present embodiment configured as described above, the signal of the grounded sheath thermocouple 5 can be transmitted to the thermocouple temperature converter 21 side by the thermocouple signal switching board 23 during mold casting. . Then, the mold temperature is measured by a thermocouple, and flow monitoring and BO prediction monitoring are performed.

While casting is stopped, the thermocouple signal switching board 23 is connected to the grounding type sheathed thermocouple 5 and the resistance measuring device 17 so that the resistance can be measured. In this state, the resistance measurement device 17 measures the contact resistance of each grounded sheath thermocouple 5 and outputs the measured value to the thermocouple resistance management terminal 19.
In the thermocouple resistance management terminal 19, the resistance value of each input thermocouple is compared with a reference resistance value set in advance, and if it is within the range of the reference value, it is determined as normal and exceeds the range. If it is, it is determined as abnormal.

FIG. 4 is a graph displayed on the monitor of the thermocouple resistance management terminal 19, and graphs the data when the resistance values of the thermocouples installed on the mold 1 surface and the mold 3 surface on the long side of the mold are measured. it's shown. The horizontal axis is the thermocouple number, and indicates the number of the installed thermocouple. The vertical axis represents the contact resistance value. Moreover, the black rhombus in the figure is the first surface side, and the white square is the third surface side.
As can be seen from FIG. 4, the No. 8 and No. 10 thermocouples installed on the one surface side have higher resistance values than the other thermocouples.

  Therefore, the thermocouple resistance management terminal 19 determines whether or not the resistance value measured in No. 8 and No. 10 exceeds the preset reference value range, and if so, determines that the contact state of the thermocouple is abnormal. If it is within the range of the reference value, it is determined as normal.

  According to the present invention, the contact state of the grounded sheath thermocouple 5 can be determined online.

It is explanatory drawing of the normal / abnormal diagnosis method of the mold thermocouple which concerns on one embodiment of this invention. It is explanatory drawing of the earthing | grounding type | mold sheath thermocouple used for one embodiment of this invention. It is explanatory drawing of the normal / abnormal diagnostic apparatus of the mold thermocouple which concerns on one embodiment of this invention. It is a graph which shows the resistance value measured in the apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold copper plate 5 Grounding type sheathed thermocouple 7 Spring 9 Insulating member 17 Resistance measuring device 19 Thermocouple resistance management terminal 21 Thermocouple temperature converter 23 Thermocouple signal switching board

Claims (3)

A mold thermocouple diagnosis method for diagnosing normality / abnormality of the installation state of a temperature sensor attached to a mold of a continuous casting facility,
A grounding type sheathed thermocouple is attached as the temperature sensor in a state where it is mechanically pressed against the mold side and is electrically insulated except for the tip of the grounding type sheathed thermocouple. An electrical resistance between a positive terminal and / or a negative terminal and the mold body is measured, and when the measured value is out of a predetermined reference range, the thermocouple is determined to be abnormal. Diagnosis method. A mold thermocouple diagnostic device for diagnosing normality / abnormality of the installation state of a temperature sensor attached to a mold of a continuous casting facility,
A grounding-type sheath thermocouple attached in a state of being mechanically pressed against the mold; attachment means for attaching the grounding-type sheath thermocouple in a state of being electrically insulated except for the tip; and A resistance measuring device for measuring the electrical resistance between the plus terminal and / or the minus terminal and the mold body, and determining that the thermocouple is abnormal when the resistance value measured by the resistance measuring device exceeds a preset range A mold thermocouple diagnosis device, comprising: a determination unit; A mold thermocouple diagnosis device that is provided in a mold temperature management device equipped with a thermocouple temperature converter that inputs a temperature measurement signal of a grounded sheath thermocouple and converts it into a temperature, and diagnoses the normality / abnormality of the mold thermocouple. There,
A connection between the plus terminal and / or minus terminal of the grounded sheath thermocouple and the resistance measuring device, and a connection between the plus terminal and / or minus terminal of the grounded sheath thermocouple and the thermocouple temperature converter are mutually connected. The mold thermocouple diagnosis device according to claim 2, further comprising a thermocouple signal switching means for switching.

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