JPH0925549A - Radiation thermometer in hot dip plating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent stains in the tip face of a fiber cable and the increase of the temp. of the cable into a high one, in an optical fiber thermometer in a plating device horizontally passing through a steel strip, by connecting an inert gas feeder to the base side of a protective tube inserted into the circumference of the fiber cable. SOLUTION: A protective tube 23 of heat resistant steel whose tip part is opened into the circumference of an optical fiber cable 1 is inserted into a pretreating furnace 3. The protective tube 23 is made of double tubes, and when gaseous nitrogen is fed from a nitrogen bomb 34, it enters the outer circumference of the inside tube 25 of the protective tube 23 and rises since the lower end of the inside tube 25 is fixed to a bolt 35. This gaseous nitrogen flows between the inside and outside tubes 25 and 24 and is discharged in the direction of the inside tube 25 from the discharging port 37 of a disk since the lower end of the outside tube 24 is stuck to the lower flange 27. Thus, the cable 1 is cooled, and furthermore, the sticking of fallen scales and foreign matters to the tip of the cable 1 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation thermometer used for measuring the temperature of a steel strip by inserting the tip of an optical fiber cable into a pretreatment furnace of a hot dip coating apparatus and inserting it into the pretreatment furnace. The present invention relates to a cable whose front end surface is prevented from being soiled.

[0002]

2. Description of the Related Art Hot-dip galvanized steel sheets such as zinc, aluminum and their alloys are manufactured by hot-dip galvanizing equipment such as Sendzimir method and non-oxidizing furnace method in which pretreatment of steel strip is performed by gas reduction. When the temperature of the steel strip in the processing furnace is low, non-plating occurs. On the contrary, when the temperature is high, the alloy layer of the plating layer develops and the plating adhesion decreases. For this reason, when manufacturing a hot-dip plated steel sheet, the furnace atmosphere temperature and the steel strip temperature in the pretreatment furnace are measured to control the steel strip to an appropriate reduction temperature.

As this thermometer, a thermocouple with a sheath for measuring the ambient temperature in the furnace and a camera type radiation thermometer for measuring the radiant energy of a steel strip with a CCD or the like have been used. Although the temperature is reliable, the outer circumference is sealed
Since it is covered with the soot, the response is slow, and it is difficult to immediately set the target temperature when the temperature is changed according to the plate thickness. On the other hand, the latter is the radiant energy of the steel strip.
Are collected in the CCD by the lens, and two kinds of filters that pass only energy rays of a specific wavelength in front of the CCD are rotated by rotating a chopping rotating plate provided on the opposite side by 180 degrees. CC only energy lines
The temperature of the steel strip is measured by the intensity ratio of the radiant energies of two kinds of wavelengths, and the responsiveness is good. Here, the reason for controlling by the intensity ratio of the radiant energy of two kinds of wavelengths is that the measured value is more reliable than that of controlling by one kind of wavelength.

However, since the lens faces the lower side of the steel strip, the scale falling from the steel strip covers the lens,
Moreover, the intensity ratio of the radiant energy of the two wavelengths does not change even when the lens is covered with a scale and the intensity of the radiant energy passing through decreases. Therefore, the measured value and the actual strip temperature are not changed. However, there was a drawback that there was an error. Also, CCD
However, even if the incident radiant energy has one or a plurality of wavelengths, the incident radiant energy cannot be continuously converted into an electric signal, so that there is a drawback that the measurement becomes discontinuous.

For these reasons, in recent years, radiation thermometers using photoelectric devices that do not have the above problems have been used. This thermometer has a monochromatic thermometer that measures with radiant energy of one type of wavelength and a two-color thermometer that measures with two types of wavelength, but the former is affected by the emissivity of the steel strip and its accuracy is poor. , The latter is often used. Further, the detection sensor is not inserted in a high temperature furnace, but is guided by a heat resistant optical fiber cable and sent to a thermometer. FIG. 3 shows a two-color thermometer of this type. The optical fiber cable 1
Is inserted into the furnace from the lower furnace wall 4 of the pretreatment furnace 3 for passing the steel strip 2 horizontally, and the tip is directed toward the lower surface of the steel strip 2. This optical fiber cable 1 is inserted into a single holding tube 5 in order to make the tip stand upright in the furnace, but the tip is between two support rollers 5a arranged close to each other. And the end is surrounded by these rolls and the steel strip 2, and the radiant energy of the steel strip 2 is the optical fiber.
It is arranged so that it does not enter the cable 1. Here, the reason why the tip of the optical fiber cable 1 is not inserted into the furnace from the upper furnace wall 6 is that the radiant energy from the burner, the heating tube or the like is incident.

The base of the optical fiber cable 1 is connected to a thermometer 7 arranged outside the pretreatment furnace 3, and the radiant energy of the steel strip 2 is continuously converted into an electric signal by a photoelectric element. Then, the temperature is displayed. The thermometer 7 is a well-known one, and is roughly composed of a converter unit 8, a computing unit unit 9 and a temperature display panel unit 10. The base of the optical fiber cable 1 is connected to the converter unit 8. There is. In the converter section 8, the light from the steel strip 2 is passed through the lens 11 to the half mirror-1
The light is condensed to 2 and is divided into reflected light 13 and transmitted light 14 by the half mirror 12, and the reflected light 13 is converted into the first filter-1.
At 5, light of wavelength λ ₁ is transmitted.

The transmitted light of wavelength λ ₁ is InGaAs
The voltage is converted by the element 16 and amplified by the preamplifier 17,
The first converter 18 converts the electric signal for calculation. The transmitted light 14 also has a similar circuit, and only the light of wavelength λ ₂ is transmitted by the second filter-19, and then the InGaAs device 2
The voltage is converted into a voltage by 0, amplified by the preamplifier 21, and converted by the second converter 22 into a calculation electric signal. Here, the second filter -19 not transmit light having a wavelength longer than the first filter 15, the wavelength has become lambda ₁ <lambda _2. The outputs of the first converter 18 and the second converter 22 are input to the arithmetic unit 9 and the voltage ratio E corresponding to the ratio λ ₁ / λ ₂ of the wavelength λ ₁ and the wavelength λ _2.
1 / E ₂ is calculated and the ratio is displayed as temperature on the temperature display panel section 10.

By the way, when the optical fiber cable 1 is inserted into the pretreatment furnace 3, in order to improve the measurement accuracy, the tip of the cable is not protected with a cover or the like, and the light from the steel strip 2 is directly exposed. I received it, and also inserted the cable with the cable exposed. However, when inserted in this manner, scale adhering to the steel strip 2 and the furnace - le or foreign matter may fall, Ke - covers the tip of the cable, the wavelength lambda ₁ and the ratio lambda ₁ / lambda ₂ wavelength lambda ₂ is Even if they are the same, their absolute values become small, so that there is a problem that the accurate temperature of the steel strip 2 cannot be measured. Even if the cable is heat-resistant, the heat-resistant resin is present between the core and the stainless steel exterior, so if it is exposed in the furnace, the heat-resistant resin deteriorates because the temperature in the furnace is high. There was also the problem of being lost.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a radiation temperature in a hot dip coating apparatus in which the tip of an optical fiber cable is not covered by a falling scale or foreign matter and the cable does not reach a high temperature. It provides a total.

[0010]

SUMMARY OF THE INVENTION According to the present invention, the tip of an optical fiber cable is passed below a steel strip threading position of a pretreatment furnace for horizontally passing a steel strip of a hot dipping apparatus. In the radiation thermometer inserted so that the bottom side of the sheet steel strip faces, and the base side of the cable was connected to a thermometer, the tip was opened around the optical fiber cable inserted in the pretreatment furnace. The protective tube was inserted, and the inert gas supply device was connected to the base side of the protective tube.

[0011]

Since the inert gas supply device is connected to the base side of the protective tube, when the inert gas is supplied to the protective tube, the inert gas passes through the gap between the optical fiber cable and the protective tube. It is discharged from the tip of the protective tube. Since the discharged inert gas is blown above the tip of the cable, it blows away the scale and foreign matter that fall to the tip of the cable,
Prevents adhesion. Further, since the inert gas passing around the cable cools the cable, the temperature of the cable does not rise.

The material of the protective tube does not reach a high temperature during the supply of the inert gas because the protective tube itself is also cooled by the inert gas, but the supply of the inert gas was interrupted due to a failure of the inert gas supply device. In this case, since the temperature becomes high, it is preferable to use a heat-resistant material such as heat-resistant chrome steel or ceramics. If the protective tube is only inserted in the periphery of the cable, the cable will bend easily and the distance between the tip of the cable and the steel strip will change easily. It is preferable to use a double-structured tube slightly thicker than the cable so that the cable does not bend inside.

The protective tube is formed by squeezing the tip into a rod shape so as not to cover the tip of the cable, or by bending the tip inward at a right angle to cover the periphery of the cable in a ring shape. It is preferable to provide a discharge port that is directed obliquely to the central portion so that the discharged inert gas collects above the tip of the cable. The tip of the protective tube is preferably the same as or higher than the tip of the cable. If the hot dip equipment stops due to an accident and the atmosphere enters the pretreatment furnace and the tip of the cable projects from the tip of the protective tube, the projecting portion will be oxidized. Since the tip of the cable is cooled while being sealed with an inert gas, it is not oxidized. Nitrogen gas is usually used as the inert gas.

[0014]

FIG. 1 shows an optical fiber thermometer according to the present invention. The optical fiber cable 1 has a tip like a conventional radiation thermometer whose tip is a lower furnace wall 4 of a pretreatment furnace 3. Is inserted into the furnace, the tip is directed toward the lower surface of the steel strip 2, and the base side is connected to the converter section 8 of the thermometer 7. Converter section 8,
The arithmetic unit 9 and the temperature display panel 10 are the same as the conventional ones.

The optical fiber cable 1 is inserted into the pretreatment furnace 3 by inserting the cable into the heat-resistant steel protective tube 23. The protection tube 23 is a double tube consisting of an outer tube 24 and an inner tube 25 longer than the outer tube 24. The optical fiber cable 1 is inserted into the inner tube 25, and there is no space between the outer tube 24 and the inner tube 25. It is an active gas channel. The inner tube 25 has an inner diameter slightly larger than the thickness of the optical fiber cable 1,
The cable is bent so that the height of the tip of the cable does not change. The lower end of the outer tube 24 has a hole 26 in the center.
The block body 2 fixed to the outside of the hole 26 of the opened lower flange 27, the inner pipe 25 penetrating the hole 26 of the lower flange 27, and fixed to the lower surface of the lower flange 27.
8 has been reached.

The block body 28 has a horizontal screw hole 29 and a vertical screw hole 30 communicating with the horizontal screw hole 29. The horizontal screw hole 29 is connected to an inert gas supply pipe 31 to form the nipple 3.
2 is screwed. An on-off valve 33 is connected to the inert gas supply pipe 31 on the way, and is connected to a nitrogen cylinder 34. On the other hand, the vertical screw hole 30 is located below the hole 26 formed in the lower flange 27, a bolt 35 is screwed therein, and the lower end of the internal pipe 25 is fixed to the tip thereof.
Further, the optical fiber cable 1 is provided at the center of the bolt 35.
Is inserted and holds the cable. This bolt 3
The optical fiber cable 1 held by 5 extends into the inner tube 25, and its tip is the same as the tip of the inner tube 25. The tips of the inner tube 25 and the outer tube 24 are connected by a ring-shaped disc 36, and the disc 36 is provided with an optical fiber cable.
As shown in FIG. 2, four discharge ports 37 that are obliquely inclined in the direction of the tip of the bull 1 are concentrically formed.

Above the lower flange 27, the outer pipe 24
The loosely fitted upper flange 38 is arranged, and the screw rod 39 penetrates both flanges. And screw rod 3
A nut 40 is provided above and below the lower flange 27 through which
However, nuts 41 are screwed onto the upper and lower sides of the upper flange 38. A bellows 42 is fixed between the lower flange 27 and the upper flange 38 so that the nut 40 can adjust the distance between the lower flange 27 and the upper flange 38. The protective pipe 23 between the upper flange 38 and the lower furnace wall 4 of the pretreatment furnace 3 is put in a suspending pipe 43, and the suspending pipe 43 is located above the upper flange 38 and the lower furnace wall 4. Is stuck to.

In this thermometer, when nitrogen gas is supplied from the nitrogen cylinder 34, since the lower end of the inner pipe 25 of the protective pipe 23 is fixed to the bolt 35, it enters the outer periphery of the inner pipe 25 and rises. The rising nitrogen gas is fixed to the lower flange 27 at the lower end of the outer pipe 24.
And the inner tube 25, and is discharged from the discharge port 37 of the disc 36 in the direction of the inner tube 25, and the scales and foreign substances that have fallen are attached to the tip of the optical fiber cable 1. To prevent.

The atmosphere gas of the pretreatment furnace 3 is the suspension pipe 4
3 through the outer tube 24 of the protective tube 23 and the upper flange 38
It flows out from the gap of to the velocity 42, but velocity 4
Since 2 is fixed to the lower flange 27 and the upper flange 38, it does not flow out. Further, the heating temperature of the steel strip 2 may change depending on the steel type and thickness, but when the temperature of the steel strip 2 is low, if the distance between the steel strip 2 and the tip of the optical fiber cable 1 is constant, The radiant energy is weak and the temperature of the steel strip 2 cannot be accurately measured. However, the protection tube 23
Since the fixed lower flange 27 of the above can be moved up and down, the distance from the steel strip 2 can be adjusted.

[0020]

As described above, the radiation thermometer of the present invention is
Since the inert gas is discharged from the tip through the protective tube in which the optical fiber cable is inserted, the optical fiber cable is cooled, and the steel strip and the pretreatment furnace are used. Even if a scale or foreign matter falls, it is blown off above the tip of the optical fiber cable and does not adhere to the tip of the cable.

[Brief description of drawings]

FIG. 1 shows a structure of a radiation thermometer of the present invention.

FIG. 2 is a plan view of the tip of the protective tube.

FIG. 3 shows a configuration of a conventional radiation thermometer.

[Explanation of symbols]

1 ... Optical fiber cable, 2 ... Steel strip, 3 ... Pretreatment furnace,
4 ... Lower furnace wall, 5 ... Holding tube, 5a ... Support roll, 6
... upper furnace wall, 7 ... thermometer, 8 ... converter section, 9 ... arithmetic unit section, 10 ... temperature display panel section, 11 ... lens, 12 ... harf mirror, 13 ... reflected light, 14 ... transmitted light, 15 ... First
Filter-, 16 ... InGaAs element, 17 ... Preamplifier, 18 ... First converter, 19 ... Second filter-, 20 ...
InGaAs element, 21 ... Preamplifier, 22 ... Second converter, 23 ... Protective tube, 24 ... External tube, 25 ... Internal tube, 26
... hole, 27 ... lower flange, 28 ... block body, 29 ...
Horizontal screw hole, 30 ... Vertical screw hole, 31 ... Inert gas supply pipe,
32 ... Nipple, 33 ... Open / close valve, 34 ... Nitrogen cylinder, 3
5 ... Bolt, 36 ... Disc, 37 ... Discharge port, 38 ... Upper flange, 39 ... Screw rod, 40 ... Nut, 41 ... Nut,
42 ... Bellows, 43 ... Suspension pipes,

Claims (3)

[Claims] 1. An optical fiber cable whose tip is directed to the lower surface side of a strip steel strip below a strip strip position of a pretreatment furnace for horizontally stripping a strip strip of a hot dip galvanizing apparatus. Optical fiber cable inserted in the pretreatment furnace in a radiation thermometer in which the base side of the cable is connected to the outside thermometer.
A radiation thermometer in a hot dip galvanizing apparatus, characterized in that a protective tube having an open tip is inserted around the bull, and an inert gas supply device is connected to the base side of the protective tube. 2. The radiation thermometer in a hot dip coating apparatus according to claim 1, wherein the protective tube is a double-structured tube, and the inner tube is inserted into the optical fiber cable. 3. The hot dip coating according to claim 1, wherein the protective tube is inserted into the furnace from the lower furnace wall of the pretreatment furnace so as to be vertically movable with respect to the lower furnace wall. Radiation thermometer in the device.