JPH0921702A - Air purge system for heat mass detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a malfunction of a heat mass detector due to flame or black smoke. SOLUTION: The heat mass detectors 4, 5, 6 comprise a photodetector for detecting the light radiated from a red heat mass and detect the presence of heat mass based on the output signal therefrom. High pressure air purge nozzles 10, 11, 12 and high capacity air purge wrapper pipes 7, 8, 9 are disposed on the prestage of each of heat mass detectors 4, 5, 6 and respectively coupled with high pressure air supply through solenoid valves 23, 24, 25, 16, 17, 18. The moment of time when the forward end of heat mass arrives at each of the heat mass detector 4, 5, 6 is predicted at an air purge control section 28 using a timer from a detection signal of biting heat mass delivered from the rolling load detector 27 for a roll 1 and each of the solenoid valves 23, 24, 25, 16, 17, 18 is opened instantaneously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents erroneous detection due to flames or black smoke in a hot lump detector for detecting hot lumps, particularly in hot steel pipe length measurement requiring highly accurate detection timing. Air purge device for

[0002]

2. Description of the Related Art Generally, a hot lump detector (Ho
t Metal Detector (hereinafter referred to as HMD) is used, and the length of the steel pipe can be measured by detecting the tip of the steel pipe by this HMD and combining it with a length meter. In general, as a light receiving element of an HMD that receives radiant light emitted from a heat mass, a photoelectric element containing silicon (Si), germanium (Ge), lead sulfide (PbS) or the like as a main component is used.

For example, as shown in FIG. 5, a hot-measuring device for steel pipes is provided with HMDs 42, 43 and a laser Doppler speed meter (length measuring device) 44 at predetermined intervals on the exit side of a rolling roll 41. The rolling load detector 45 is installed on the rolling roll 41, the rear end of the steel pipe 46 is pushed by a pusher (not shown) to cause the leading end of the steel pipe 46 to be caught in the rolling roll 41, and rolled by rolling and rolling the rolling roll 41. The steel pipe 46 advances. Laser Doppler speedometer 44
Can be detected when the rolling load detector 45 detects that the tip of the steel pipe 46 is caught in the rolling roll 41.

The laser Doppler type speedometer 44 comprises a steel pipe 4
When the tip of 6 reaches the HMD 42, the measurement is started and the fixed length L ₁ is preset. When the extended length L of the steel pipe 46 is longer than the fixed length L ₂ , the tip of the steel pipe 46 is HMD.
Upon reaching 43, the laser Doppler speedometer 44 resets the fixed length L ₁ and instead presets the fixed length L ₂ . And the laser Doppler speedometer 44
Is completed when the rear end of the steel pipe 46 passes through the rolling rolls 41, 41 and the value measured by the rolling load detector 45 decreases, and the length L of the steel pipe 46 is L = L ₂ +
It is calculated by L ₃ . However, L ₃ is the laser Doppler speedometer 44 from the start of operation of the HMD 43 to the completion of length measurement.
Is the measured length value integrated by.

In the hot length measurement of the steel pipe, when measuring a steel pipe having a surface temperature of 1100 ° C. to 1200 ° C., since the rear portion of the steel pipe is closed by a plug, as shown in FIG. When a lubricant such as graphite used is burned, a flame 48 having a length of about 300 to 500 mm is generated from the tip of the steel pipe 46 and the light receiving element of the HMD 43 is operated by the radiant light emitted from the flame 48. is there. For example, as shown in FIG. 7, the HMD
When 43 is operated by the flame 48 at the tip of the steel pipe 46, the tip of the steel pipe 46 is detected as having arrived even though it has not yet arrived, and malfunctions. Therefore, the preset length L ₂ is preset. The timing is faster,
Measured length value L ₃ from the start of HMD43 operation to the completion of length measurement
Will be measured for a long time.

Further, depending on the type of lubricant used and the difference in rolling temperature, black smoke 49 may occur from the tip of the steel pipe 46 together with the flame 48, as shown in FIG. As a pattern thereof, as shown in FIG. 8A, when black smoke 49 is generated between the flame 48 and the steel pipe 46 and covers the tip of the steel pipe 46, as shown in FIG. Four
8 and black smoke 49 may coexist and cover the tip of the steel pipe 46.

As shown in FIG. 8 (a), when black smoke 49 is generated between the flame 48 and the steel pipe 46 and covers the tip of the steel pipe 46, as shown in FIG. 9 (a), As in the case of only the flame shown in FIG. 6, the measured length value L ₃ is detected long. On the other hand, as shown in FIG. 8B, when the flame 48 and the black smoke 49 are mixed and cover the tip of the steel pipe 46, the tip of the steel pipe 46 has already reached as shown in FIG. 9B. HMD despite doing
Since 43 is not operating, the preset timing of the fixed length L ₂ is delayed, and the measured length value L ₃ from the operation start of the HMD 43 to the completion of the length measurement is measured short.

As a method of preventing the malfunction due to the flame or black smoke of the HMD, a method of adjusting the threshold level setting of the HMD, a photoelectric element having a proportional relationship between the wavelength and the output voltage is used to remove ambient light, A method of detecting a steel pipe by HMD (Japanese Patent Laid-Open No. 55-164316), an optical filter for removing a light spectrum of a flame generated in a heat block is provided, and the light detecting means receives radiant light transmitted through the optical filter. In order to prevent malfunctions due to flame (Japanese Patent Laid-Open No. 62-134588), a predetermined operation time set value is set in the operation signal determination device, the output signal operation time of the light receiving element is compared, and the set operation time is set. A method of determining that the operation is caused by heat lumps above a set value and outputting a heat lump detection signal (Japanese Patent Laid-Open No. 6-194224), a predetermined integral amount is set in the operation signal determination device. Method, comparing with the integrated value of the output signal of the light receiving element, and outputting the heat lump detection signal when the integrated value of the output signal reaches or exceeds the set integral amount (Japanese Patent Laid-Open No. 6-194225), etc. Is proposed.

[0009]

The method for adjusting the threshold level setting of the HMD is not applicable when the detection element output level of the flame is higher than the detection element output level of the steel pipe, and is black. In the case of smoke, we cannot handle it. The methods disclosed in JP-A-55-164316 and JP-A-62-134588 are
It is considered that the optical spectrum of the flame changes depending on the nature, color and temperature of the flame, and it is doubtful that the malfunction of the HMD due to the flame can be reliably prevented. That is, JP-A-62
In Japanese Patent No. 134345, the radiant light of the flame emitted from the heat mass has an emission line spectrum having a wavelength peculiar to a certain element, but in the experimental investigation results of the present inventors, the flame showed a continuous spectrum. The peak wavelength of the flame is 590
mm and 770 mm, this flame is visible from visible light to 2000
It is considered to be a continuous spectrum in the infrared region of nm or more, and it seems that it is extremely difficult to capture only the heat lump with a bandpass filter. Furthermore, black smoke cannot be discriminated by an optical filter. Furthermore, JP-A-6
The methods disclosed in Japanese Patent Application Laid-Open No. 194224/1994 and Japanese Patent Application Laid-Open No. 6-194225 have an effect in the case of only flames, but when the flames and black smoke are mixed, it is possible to accurately detect the tip of the heat mass. Can not.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide an air purging device for a heat lump detector capable of reliably preventing malfunction due to the flame and black smoke of the HMD.

[00011]

The inventors of the present invention fundamentally detect flame and black smoke without relying on the processing on the HMD side to detect the tip of a steel pipe in which flame and black smoke are mixed in order to achieve the above object. The test study was repeated about the purging method in order to remove. As a result, a high-pressure air purge nozzle and a large-capacity air purge pipe are provided before the position where the HMD detects the tip of the steel pipe, and by instantaneously performing the air purge, the flame can be removed by the high-pressure air purge, and the large-capacity air purge pipe can be obtained. It was confirmed that the black smoke can be removed by air purging, and the present invention was reached.

That is, the present invention provides a heat lump detector that includes a photodetector for detecting radiant light emitted from a red-hot heat lump and detects the presence or absence of the heat lump based on an output signal from the photodetector. , A high-pressure air purge nozzle and a large-capacity air purge wrapper pipe are arranged in front of each heat-lump detector for detecting the presence or absence of the heat lump, and a high-pressure air supply source or a large-capacity air supply source is respectively provided via a solenoid valve. The air purge control unit predicts the moment when the tip of the hot mass reaches each hot mass detector from the detection signal of biting of the hot mass by the rolling load detector of the rolling roll, and momentarily opens each solenoid valve. It is an air purging device for a heat lump detector characterized in that

[0013]

DETAILED DESCRIPTION OF THE INVENTION The details of the present invention will be described below with reference to FIGS. FIG. 1 is an overall explanatory view of an HMD air purge device of the present invention, FIG.
FIG. 3 is an explanatory view of the positional relationship of the air purging device of the HMD at the frontmost stage, and FIG. 3 is a graph showing an output analog signal of the HMD detection element by the steel pipe and an example of an operation contact output signal when the analog signal is processed.

1 and 2, 1 is a rolling roll of a hot pipe making line, 2 is a steel pipe produced by the rolling roll 1, 3 is a laser Doppler type speed arranged on the exit side of the rolling rolls 1, 1. Reference numerals 4, 5, and 6 are HMDs arranged at a predetermined interval after the laser Doppler type speedometer 3 on the exit side of the rolling roll 1, and each detects the timing at the position where the tip of the steel pipe 2 reaches. To do. The laser Doppler type speedometer 3 is a system for measuring the length together with the timing signal that the tip of the steel pipe 2 of each HMD 4, 5 and 6 has reached. 7, 8 and 9 are large-capacity air purge wrapper pipes for blowing off black smoke arranged at the positions of the HMDs 4, 5 and 6, 10, 11 and 12 are also the HMDs 4, 5 and 5, respectively.
6 is a high pressure air purge nozzle for blowing off the flame disposed at the position 6.

Numerals 13, 14 and 15 are receiver tanks each having a capacity of about 60 liters, which are connected to the large-capacity air purge wrapper pipes 7, 8, 9 by piping via solenoid valves 16, 17, and 18, respectively. 14 and 15 are 7 kgf
/ Cm ² · G, 2000 l / min It is connected by a pipe to a compressor 19 which supplies compressed air. 20,
21 and 22 are high pressure air purge nozzles 10, 11 and 1
2 is a receiver tank with a capacity of about 30 liters, which is connected by piping via solenoid valves 23, 24, 25, and each receiver tank 20, 21, 22 is 15 kgf / cm ² · G,
It is connected by a pipe to a compressor 26 that supplies high-pressure air at 1000 l / min. 27 is a rolling load detector that detects the timing at which the tip of the steel pipe 2 bites into the rolling rolls 1, 1, 28 is an air purge control unit, and the tip of the steel pipe 2 input from the rolling load detector 27 is the rolling roll 1, Based on the timing of biting into 1, each HMD4,
Predict the moment when the tip of the steel pipe 2 reaches 5 and 6,
The solenoid valves 16, 17, 18 and 23, 24, 25 are configured to be opened for 2 to 3 seconds before and after the tip of the steel pipe 2 reaches D4, 5, and 6.

The arrangement of the large-capacity air purge wrapper pipes 7, 8, 9 and the high-pressure air purge nozzles 10, 11, 12 at the positions of the HMDs 4, 5, 6 are as follows. 8 and 9 and each high pressure air purge nozzle 1
0, 11, 12 do not block the visual field of each HMD 4, 5, 6,
Moreover, the purging direction of each air is set so as not to face the HMDs 4, 5, and 6. For example, as shown in FIG. 2, the large-capacity air purge wrapper pipe 7 is arranged so as to purge perpendicularly to the advancing direction of the steel pipe 2 and directly from the side, and the high-pressure air purge nozzle 10 is opposite to the advancing direction of the steel pipe. In the direction and purge from below. In addition, HMD4
Are arranged on the side of the large capacity air purge wrapper pipe 7 and the high pressure air purge nozzle 10.

With the above-described structure, the rolling of the steel pipe 2 is started by the rolling rolls 1 and 1, and the signal from the rolling load detector 27 to the rolling rolls 1 and 1 at the tip of the steel pipe 2 is sent to the air purge controller. When input to 28,
Based on the timing at which the tip of the steel pipe 2 bites into the rolling rolls 1 and 1, the moment when the tip of the steel pipe 2 reaches each HMD 4, 5 and 6 is predicted, and the tip of the steel pipe 2 reaches each HMD 4, 5 and 6. Before and after each solenoid valve 16, 17, 18 and 23,
24 and 25 are opened for 2 to 3 seconds, and each of the large-capacity air purge wrapper pipes 7, 8 and 9 is less than 10 kgf / cm ² · G,
1400 l / min or less, eg 7 kgf / cm ² ·
G, 2000 l / min, and from each high-pressure air purge nozzle 10, 11, 12 to 10 kgf / cm 2 · G or more, for example, 15 kgf / cm ² · G, 1000 l / mi
Air purging is performed with n, and black smoke ejected from the tip of the steel pipe 2 is blown off by the large-capacity air purge from the large-capacity air-purging wrapper pipes 7, 8, 9 and the high-pressure air-purging nozzles 10, 11, 12 respectively. Due to the high-pressure air purge, the flame ejected from the tip of the steel pipe 2 is blown away, and the influence of flame and black smoke can be eliminated. Therefore, as shown in FIG. 3, the output waveforms of the photoelectric elements of the HMDs 4, 5 and 6 are not disturbed due to the influence of flame and black smoke, and the tip of the steel pipe 2 can be accurately detected with good timing. Therefore, it becomes possible to accurately measure the extended length of the steel pipe 2.

The pressure, volume, injection time of the air purge and the receiver tanks 13, 14, 1 according to the present invention.
For capacities 5, 20, 21 and 22, the flame and black smoke pattern of the targeted heat mass varies depending on the rolling equipment or the lubricant used, but there is a unique pattern for each equipment, Correspondingly, it may be set individually. For example, when the heat mass is the steel pipe 2, the pressure of the high-pressure air jetted from the high-pressure air purge nozzles 10, 11, 12 is 10 kg / cm ² · G or more, and the large-capacity air purge wrapper pipes 7, 8, 9 are used. From 10 kg / cm ²
・ Less than G, 1400 l / min or more, purge time is
2-3 seconds is sufficient for each HMD. The capacity of the receiver tanks 13, 14, 15, 20, 21, 22 is not particularly limited, but large capacity air purge wrapper pipes 7, 8, 9 are provided.
The receiver tanks 13, 14, 15 connected to the receiver should have a larger capacity than the receiver tanks 20, 21, 22 connected to the high-pressure air purge nozzles 10, 11, 12, for example, twice or more.

When hot rolling a steel pipe having an outer diameter of 110.0 mm and a wall thickness of 7.5 mm at about 800 ° C. and a rolling speed of 6 m / min and using graphite as a bar lubricant, an air purge device is used to perform an air purge. The distribution of variation between the length-measuring value and the actually-measured value was measured for each of the case where the measurement was performed and the case where the air purge was not performed. FIG. 4 shows the results. As shown in FIGS. 4A and 4B, the variation between the length measurement value and the actual measurement value before and after the air purge is reduced to about 1/2 due to the variation of 3σ, and the effect is clear.

[0020]

As described above, according to the present invention,
It is possible to prevent the detection timing deviation of the HMD steel pipe tip due to the flame and black smoke from the hot steel pipe tip, and to reliably detect the hot steel pipe tip, so the length measurement accuracy of the hot steel pipe length meter is greatly improved. .

[Brief description of drawings]

FIG. 1 is an overall explanatory view of an HMD air purge device of the present invention.

FIG. 2 is a front view showing the arrangement of an air purging device for the frontmost HMD.

FIG. 3 is a graph showing an HMD detection element output analog signal by a steel pipe and an example of an operation contact output signal when the analog signal is processed.

4A and 4B show distributions of variations in length measurement values and actual measurement values before and after air purge is performed. FIG. 4A shows before air purge, and FIG. 4B shows after air purge.

FIG. 5 is an overall configuration diagram showing a length measuring principle of a hot steel pipe length measuring device.

FIG. 6 is a schematic view showing a state of a flame from the tip of a hot steel pipe.

FIG. 7 is a graph showing an example of an HMD detection element output analog signal and an operation contact output signal when the analog signal is processed.

FIG. 8 is a schematic view of a state where flames and black smoke are ejected from the tip of the hot steel pipe, and FIG. 8A shows a case where black smoke is generated between the flame and the steel pipe to cover the steel pipe tip. The figure shows the case where flame and black smoke are mixed and the steel pipe tip is covered.

9 is a graph showing an output analog signal of the HMD detection element of FIG. 8 and an example of an operation contact output signal when the analog signal is processed. FIG. 9A is a diagram of FIG. 8A and FIG. 8
This is the case of (b).

[Explanation of symbols]

 1,41 Rolling rolls 2,46 Steel pipes 3,44 Laser Doppler type speedometers 4, 5, 6, 42, 43 HMD 7, 8, 9 Large capacity air purge wrapper pipes 10, 11, 12 High pressure air purge nozzles 13, 14 , 15, 20, 21, 22 Receiver tank 16, 17, 18, 23, 24, 25 Solenoid valve 19, 26 Compressor 27, 45 Rolling load detector 28 Air purge control unit 48 Flame 49 Black smoke

Claims (1)

[Claims] 1. A heat lump detector for detecting the presence or absence of the heat lump based on an output signal from the light detection element, the heat lump detector comprising: A high-pressure air purge nozzle and a large-capacity air purge wrapper pipe are arranged in front of each hot-lump detector that detects the presence or absence of a lump, and each is connected to a high-pressure air supply source or a large-capacity air supply source via a solenoid valve, Based on the detection signal of the trapping of the hot mass by the rolling load detector of the rolling roll, the air purge control unit predicts the moment when the tip of the hot mass reaches each hot mass detector, and it is possible to momentarily open each solenoid valve. Air purging device for the characteristic heat mass detector.