JPH07128041A - Method for measuring plate thickness - Google Patents

Abstract

PURPOSE:To eliminate dead zone during an interval from the start of measurement to an average operating time by measuring the plate thickness based on the weighted average of data for every reference counting time during that interval. CONSTITUTION:Radiation from a radiation source 2 transmits through an object to be measured (thick plate) 1 in the arrow direction and impinges on a detector 3. A detected signal 3 is processed at an input circuit section 5 which delivers a pulse signal corresponding to the plate thickness to an processing unit 6. The processing unit 6 counts the number of pulses every reference counting time and for the interval from start of measurement to an average operating time, a weighted average AXn of data is determined for every set reference counting time according to a formula I {in the formula, k: average operating time/reference counting time (fractions are raised to a unit), n: number of counts x}. Upon reaching the average operating time, moving average BXn of the counts (x) for every reference counting time is determined according to formula II. This method eliminates the dead zone and realizes a highly accurate high response thickness gauge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate thickness measuring method for measuring the thickness of a steel plate or the like by utilizing radiation or the like.

[0002]

2. Description of the Related Art In the rolling and refining processes of steel and the like, continuous thickness measurement is required as an important element of product quality control. The plate thickness was measured based on the moving average of the data for each.

[0003]

In the thickness gauge, the variation of the measurement result, that is, the statistical error, which is an important factor for determining the measurement accuracy, is

[0004]

[Equation 4] Here, σ is defined as relative standard deviation N: count value (CPS) T: measurement time (S).

The value allowed for this statistical error in terms of measurement accuracy is about 0.05% at 90% reliability, so the measurement time is 0.4
S is required. However, if the measurement time of 0.4 S is allowed, the object to be measured will move by 1 m or more at a normal line speed, and the dead zone will be large and it will not be put to practical use. As described above, the statistical error and the response (measurement time) bring about contradictory results, and therefore, one of them is destined to be sacrificed. Conventionally, since the plate thickness is measured based only on the moving average of data for each average calculation time, a dead zone occurs between the start of measurement and the average calculation time, and even after the average calculation time is reached Resolution was poor.

In recent years, there has been an increasing demand for quality improvement,
A dramatic improvement in the accuracy and responsiveness of thickness gauges has been demanded. Particularly in the plate rolling process for thick plates and the like, the object to be measured continuously flows, and thus there is a demand for minimizing the dead zone of the plate head.

Therefore, an object of the present invention is to provide a plate thickness measuring method which can eliminate the dead zone from the start of measurement until the average calculation time is reached and satisfy the contradictory conditions of high precision and high speed response.

[0008]

Therefore, according to the present invention, a method of arranging a pair of a radiation source and a detector so as to sandwich an object to be measured and measuring the plate thickness of the object to be measured, from the start of measurement. Measure the plate thickness based on the weighted average of the data for each set reference counting time until the set average calculation time is reached, and then use the moving average for each reference counting time after the average calculation time is reached. Based on this, the plate thickness is measured.

[0009]

The dead zone at the plate head portion is eliminated by measuring the plate thickness based on the weighted average of the data for each reference counting time from the start of measurement until the average calculation time is reached.
Even after the average calculation time is reached, the plate thickness is measured based on the moving average of the data for each reference counting time, so that the resolution with respect to the thickness change is improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, in a thickness gauge to which the present embodiment is applied, a radiation source 2 and a detector 3 are arranged at a constant interval with the object to be measured 1 interposed therebetween, and the radiation source 2 and the detector 3 are arranged in a direction of an arrow from the radiation source 2. The radiation that emits radiation and that has passed through the DUT 1 reaches the detector 3.
The detector 3 is a detector that outputs a pulse using a photomultiplier tube or the like, and a high voltage is applied from the high-voltage power supply unit 4,
The detected signal is processed into a signal that can be transmitted by the input circuit unit 5, and is input to the arithmetic processing unit 6. Since the DUT 1 is heated to around 1000 ° C in thick plate rolling and the like, it is indispensable to correct the density against temperature changes during rolling.
Then, the temperature is detected, the signal converter 8 is passed, and the correction processing is performed by the arithmetic processing unit 6. In addition, the temperature detector 7 also serves as the entry detection of the DUT 1 into the measurement position, and the signal conversion unit 8 has 600 ° C.
A plate rush signal generator (not shown) for determining the presence of a plate by the above temperature detection is included, and a measurement start signal is transmitted from here. The pulse signal corresponding to the plate thickness from the input circuit unit 5 and the temperature signal from the signal converter 8 are arithmetically processed by the arithmetic processing unit 6 and displayed on the display recording unit 9. Information on various set values such as the plate thickness and the information on the measurement results are stored in the arithmetic processing unit 6
And the upper process computer 10 communicate with each other to perform automatic measurement.

On the other hand, in order to control the thickness detection position in the plate width direction, as shown in FIG. 2, the holding body 11 to which the radiation source 2, the detector 3 and the like are attached is designed to run on the rail 12 in the plate width direction. The pulse is transmitted from the pinion 13, the rack 14, and the position transmitter 15 directly connected to the pinion 13, the rack 14, and is input to the position control device 16. The target stop position of the holder 11 is given as a set value by the arithmetic processing unit 6 together with the change of the plate width, and compared with a signal given from the position transmitter 15 by the position control unit 16 to control the voltage of the motor 17 to obtain a desired value. Stop in position.

FIG. 3 shows a calculation program executed by the calculation processing unit 6 for each set reference counting time from the start of measurement of the count value from the input circuit unit 5 until the set average calculation time is reached. 8 is a flowchart of a part of performing weighted averaging of data and performing a moving average for each reference counting time after the average calculation time is reached.

First, n is initialized (step 2).
0). Then, n is updated (step 21), pulse counting is performed every reference counting time, and x is stored (step 2).
2). Thereafter, if n <k, the process proceeds to step 24, and if not, the process proceeds to step 25 (step 23). Then, the weighted average of the count values is obtained by the following equation (1) and output (step 24). Further, the moving average of the count value is obtained and output by the following equation (2) (step 25). After that, it is checked whether the board detector 4 has detected the board exit, and if it is board exit, the procedure ends. If not, the procedure returns to step 21 (step 26).

[0014]

[Equation 5] k: Average calculation time / reference counting time (However, the first decimal point
Rounding up is an integer) n: Number of count values x: Count value

[0015]

[Equation 6] k: Average calculation time / reference counting time (However, the first decimal point
The digit is rounded up to an integer.) N: Number of count values x: Count value Next, a specific operation will be described with reference to FIG.

FIG. 4 is a plan view of an object to be measured (for example, a steel plate), where AB indicates the sheet width direction and A-D indicates the rolling direction. For example, measurement is made at the midpoint C of the sheet width. The position is set, and the temperature detector 7 for detecting the plate plunge is also arranged at the same position. On the other hand, the reference counting time is set to 0.1S and the average calculation time is set to 0.4S. In this state, when the steel plate moves in the flow direction of the arrow and advances to the measurement position, the temperature detector 7 detects the plate plunge and issues a measurement start signal to the arithmetic processing unit 6 to count 0.1a, that is, 0.1S. do. When 0.1S has elapsed, the count value is stored and 0.1S is newly added.
Continue counting. This operation is repeated until the plate comes out of the measurement position and the plate detector 4 judges that the plate has come out. On the other hand, in synchronism with the start of counting, the time judgment is performed at 0.1S intervals, and a weighted average is calculated for each 0.1S until 0.4S, that is, until the fourth data is counted (b ₁ , b ₂ , b). The weighted averaging of the data counted for each a at intervals of ₃ is performed.), 0.5S, that is, 2 when the fifth counting is completed.
Count value from the 5th count to the 5th count, 4 counts (0.4S
Interval) is output as a moving average (b ₄ ′) for each 0.1S, and the subsequent thickness calculation is performed. After that, this operation is continued until boarding.
As described above, since data is output every 0.1S from the plate plunge, a high-speed response is realized, and the average value between 0.4S is obtained, statistical error is minimized, and at the same time high accuracy is achieved. . Further, by performing the weighted averaging of b ₁ , b ₂ , and b ₃ , the variation of the data increases, but the data is effective for knowing the shape of the plate head portion.

The effect of this embodiment described above will be described in detail with reference to FIG. 5-A is a diagram showing a cross section of the plate head, and when measured by a simple average of 0.4S, data is output as a result of the shape shown in 5-a after 4a, that is, 0.4S, behind the plate head. As shown in 5-b in the moving average of 0.4S for each 0.1S, after 0.4S, the data is decomposed more than in 5-a, but the dead zone of the plate head is not improved. 5-c
Is a diagram showing data when the present embodiment is executed.
The drawbacks of the example are improved, the dead zone of the plate head is minimized, and the resolution for thickness changes is also satisfactory.

As described above, by combining the weighted average from the start of measurement and the moving average calculation method for each reference counting time, the dead zone of the plate head which could not be realized is eliminated, and The resolution against fluctuations has been significantly improved, and at the same time, the delay due to the calculation time has been minimized. It is possible to realize a thickness gauge with high accuracy and high speed response.

Equation (1) was used in obtaining the weighted average in the process 24 in FIG. 3 of the above-mentioned embodiment, but the following equation (3) or (4) or another equation that can obtain similar results is used. Even if it uses, the present invention can be realized. In the explanation, the reference counting time is
The average calculation time is set to 0.1 S and the average calculation time is set to 0.4 S, but needless to say, the present invention can be realized without being limited to this time.

[0020]

[Equation 7]

In the above equations (3) and (4), k: average calculation time / reference counting time (where the first decimal point is
Rounding up is an integer) n: Number of count values x: Count value

[0022]

As described above, according to the present invention, the dead zone from the start of measurement to the time when the average calculation time is reached is eliminated, the resolution for thickness variation is significantly improved, and at the same time, the delay due to the calculation time is minimized. Stay in the limit. Therefore, it is possible to realize a thickness meter with high accuracy and high speed response.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a radiation thickness gauge to which an embodiment of the present invention is applied.

FIG. 2 is a detailed view showing a detection system of the radiation thickness gauge shown in FIG.

FIG. 3 is a flowchart showing an embodiment of the present invention.

FIG. 4 is a diagram illustrating a measuring method according to an embodiment of the present invention.

FIG. 5 is a diagram showing measurement results in a conventional method and an embodiment of the present invention.

[Explanation of symbols]

 1 ... DUT 2 ... Radiation source 3 ... Detector

Claims (4)

[Claims] 1. A method of arranging a pair of a radiation source and a detector so as to sandwich an object to be measured and measuring the plate thickness of the object to be measured, the setting is performed from the start of measurement until the set average calculation time is reached. The plate thickness is measured based on the weighted average of the data for each reference counting time, and after the average calculation time is reached, the plate thickness is measured based on the moving average for each reference counting time. A method for measuring plate thickness. 2. A weighted average Ax for each reference counting time, which is performed from the start of measurement until the set average calculation time is reached.
The plate thickness measuring method according to claim 1, wherein _n is calculated by the following formula. [Equation 1] k: Average calculation time / reference counting time (However, the first decimal point
Rounding up is an integer) n: Number of count values x: Count value 3. A weighted average Ax for each reference counting time, which is performed from the start of measurement until the set average calculation time is reached.
The plate thickness measuring method according to claim 1, wherein _n is calculated by the following formula. [Equation 2] k: Average calculation time / reference counting time (However, the first decimal point
Rounding up is an integer) n: Number of count values x: Count value 4. A weighted average Ax for each reference counting time, which is performed from the start of measurement until the set average calculation time is reached.
The plate thickness measuring method according to claim 1, wherein n is calculated by the following formula. [Equation 3] k: Average calculation time / reference counting time (However, the first decimal point
Rounding up is an integer) n: Number of count values x: Count value