JPS58168926A - Measuring method of surface temperature distribution of material - Google Patents

Abstract

PURPOSE:To improve a measuring range and accuracy, by scanning a licenser camera in a period suitable for temperature of a material and measuring the temperature distribution of the material and then, combining the value of this temperature distribution with the absolute value of the temperature obtained by a radiation thermometer which is provided separately. CONSTITUTION:A licenser camera 2 directed toward a moving mterial 1 is provided and also, a radiation thermometer 3 is disposed as directing toward the middle point of a scanning line crossing at right angles to its moving direction. The scanning for each element of the camera 2 is carried out with high speed and a period of the scanning is varied by instructions of an operational processing device 6 basing on a signal obtained by digitalizing the output signal of the camera 2 by an A/D converter 5 and is automatically controlled to have a period suitable for the temperature of the material. On one hand, the signal of the thermometer 3 is inputted into the device 6 through an A/D converter 8 because the absolute value of the temperature is not made known by only the camera 2. Then, said signal is compared with the result obtained by the camera 2 and is outputted into a display device 9 after correcting a temperature drift etc. of the camera 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface temperature distribution measuring method for measuring the surface temperature distribution of a high temperature moving material such as a continuously cast slab using a line sensor camera and a radiation thermometer.

Conventionally, there are thermo cameras, infrared television cameras, and the like as devices for measuring the temperature distribution on the surface of a material in a non-contact manner. Although thermo cameras can determine the absolute value of temperature, they have drawbacks such as requiring liquid nitrogen to cool the detection element and having low resolution. Furthermore, although infrared television cameras can detect the temperature distribution, they do not know the absolute value, have large afterimages, and because the detection element is an image pickup tube, they have disadvantages such as distortion and lack of long-term stability. Unfortunately, none of these methods is suitable for the purpose of simply and accurately measuring the surface temperature distribution of a moving material online. Attempts have also been made to mechanically scan a radiation thermometer, which is a spot temperature measurement device, and measure its distribution.
There is a limit to the scanning speed, and under adverse conditions such as dust,
There are many failures in the scanning mechanism, which poses problems for practical use.

On the other hand, in the manufacturing process of steel slabs and steel plates, temperature measurement of materials is an important matter, and in recent years, where stricter temperature control has been required, it has become necessary to grasp the temperature of a surface rather than just measuring a point. ing. For example, when manufacturing a cis slab by continuous casting, knowing the temperature distribution on the slab surface is
This information is extremely important in controlling the distribution of cooling water and improving the quality of the pump.

However, the harsh environment of high temperature, humidity and dust
Under conditions where the installation space is also limited,
Furthermore, there is no method that can measure it stably and with high precision, and its development is strongly desired.

The present invention accurately answers such demands, and its gist is that a line sensor camera and a radiation thermometer are provided in the material movement path facing the material surface, and that the line sensor camera detects the The scanning period of the line sensor camera is changed according to the magnitude of the output signal, the temperature distribution on the material surface is measured at a scanning period suitable for the material temperature, and this temperature distribution is compared with the absolute temperature value obtained from the radiation thermometer. The objective is to measure the surface temperature distribution of the material by integrating the above.

Incidentally, semiconductor integrated circuits have made remarkable progress in recent years, and many types of optical sensors that have practical sensitivity even in the infrared region are commercially available.

The line sensor used in the present invention also applies this type of integrated circuit technology, and is also called an image sensor or a -dimensional solid-state image sensor. Therefore, some attempts have been made to apply this line sensor to temperature distribution measurement, but it seems that there is still a long way to go to put it into practical use because the following problems associated with line sensors have not been solved.

A line sensor has at most 2,000 or more photoelectric conversion elements arranged in a line, and the dimensions of each element are about 14 μm x 14 μm, and the overall size of a sensor with 2,000 elements is about 30 mm. The amount of light received by each element is photoelectrically converted and sequentially output in time series as an electrical signal. The magnitude of the output signal depends on the amount of light received by each element within the time from the signal ratio custard pulse to the next start pulse. and,
The time interval between these start pulses is called the accumulation time or scan period.

The relationship between the measurement target material, the material to be measured, and the signal output is as shown in FIG.

From the same figure, if the accumulation time is 12m5ec, approximately 830
degree, approximately 750-920r in the case of 6m5ec,
In the case of 3m5ec, it can cover the material temperature range of 850 to 1000C, but if the material temperature shows a large temperature distribution of 700 to 100OC, for example, if the storage time is fixed, the temperature of the entire range will be covered. It turns out that the distribution cannot be known.

On the other hand, the output from the line sensor changes depending on the ambient temperature and also has time drift, making it difficult to directly determine the absolute value of the temperature from the output signal of the element.

Therefore, in the present invention, the scanning period is changed depending on the magnitude of the output signal from the line sensor, so that even if the material exhibits a wide range of temperature distribution, the entire area is covered, and the absolute value of the temperature is In order to know this, a radiation thermometer is attached.

A specific example of the present invention will be described with reference to FIG. 2. A line sensor camera 2 that looks at a moving material 1
is provided, and a radiation thermometer 3 is disposed facing, for example, the midpoint of the scanning line perpendicular to the direction of movement thereof.

The scanning of each element by the line sensor camera 2 is performed at high speed, thereby providing temperature distribution over the entire surface of the material 1.

The signal output captured by the line sensor 2 receives a clock signal from the clock generator 4 and is sequentially captured by the A/D converter 5, where it is converted into a digital signal and then input to the arithmetic processing unit 6. be done. Here, the clock frequency is selected such that the signals of all elements can be output and A/D converted during a minimum accumulation time determined by the maximum temperature of the material 1. For example, the required minimum accumulation time is 1m5
When the number of elements is 1000 in ec, it is necessary to output at least one element signal for every 1μ cell, so a clock frequency of 1 MHz or more is selected.

Thus, when processing the signals input to the arithmetic processing unit 6, if the relationship between the material temperature and the storage time is appropriate, it can be executed as is, but if it is not, the relationship shown in Figure 1 can be used. Then, the following processing is performed. In other words, if there is an element that outputs a signal exceeding the saturated output value of 90ch when measured over an accumulation time of, for example, 6 m5et:, the state is determined by arithmetic processing and the start pulse generator 8 is controlled. Then, in order to correspond to the material temperature, the accumulation time was set to 3 m5ec, and the measurement was performed again. If there is still an element whose output is less than 10% of the saturated output value even though the accumulation time is 6 m5ec, the accumulation time is set to 12 m5ec and the measurement is performed again.

This allows % 12FFZsec, 6m5 for materials with wide temperature distribution from 700C to 950C
eC% Measurement with an accumulation time of 3 m5 ec allows measurement over the entire temperature range.

As mentioned above, the absolute value of temperature is unknown when the line sensor camera 2 is used alone. Therefore, the signal from the radiation thermometer 3 that measures the temperature at one point within the field of view of the camera 2 is input to the arithmetic processing unit 6 via the A/D converter 8, and the line sensor camera 2
The temperature drift of the line sensor camera 2 and the like are corrected by comparing the results obtained in , and then the results are displayed on the display device 9 . The display may include a similar color division display for each temperature range as shown in FIG. 3, a position to temperature level display as shown in FIG. 4, and the like. In the case of the method shown in FIG. 4, rewriting is performed as the material moves.

Further explaining the method of the present invention with reference to FIGS. 5 to 9, when the temperature distribution of the scanning line A-H of material 1 (see FIG. 2) shows the distribution as shown in FIG. simply 6
In the measurement of m5ec accumulation time, as shown in Figure 6, 750
Only the range of ~920C is obtained, and the other ranges are cut. On the other hand, with an accumulation time of 3m5et, we found a distribution of 850tl' or more as shown in Figure 7, and 12F
The distribution below 830C is known from the FZsec accumulation time as shown in Figure 8, and the distribution at each accumulation time is combined as shown in Figure 9.The distribution can be seen as is, but the temperature drift of the line sensor camera, etc. Since the absolute value is unknown, based on the temperature measurement result at the zero point from the radiation thermometer,
Line ■ Correct the value indicated by the sensor camera.

As described above, since the present invention is provided with a line sensor camera radiation thermometer, it is possible to correct temperature drift of the line sensor camera and perform accurate temperature photometry. Furthermore, the temperature measuring means is compact and can be used even in harsh environments, making it extremely practical.

[Brief explanation of drawings]

Fig. 1 is a correlation diagram between material temperature - line sensor camera output value - accumulation time, Fig. 2 is a schematic configuration diagram of a device for carrying out the method of the present invention, and Figs. 3 and 4 are diagrams of temperature distribution display examples. , FIGS. 5 to 9 are temperature distribution diagrams showing examples of signal processing. 1... Material 2... Line sensor camera 3... Radiation thermometer 4... Clock pulse generator 5.8... A/D converter 6... Arithmetic processing unit 7... Start Pulse generator 9...Display device patent applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Yoshihisa Nagai 12 Government-11 & Figure 2 Figure 5 Figure 6

Claims (1)

[Claims] (1) A line sensor camera and a radiation thermometer are installed on the material movement path facing the material surface, and the scanning period of the line sensor camera is changed depending on the magnitude of the output signal from the line sensor camera, and the material temperature is The surface temperature distribution of the material is measured by measuring the temperature distribution on the surface of the material at a scanning period suitable for Surface temperature distribution measurement method.