JPS63243712A - Thickness gage using x-ray - Google Patents

Abstract

PURPOSE:To dispense with the determination of a quality correction value for each target plate thickness and thereby to facilitate a setting operation for a thickness gage, by a method wherein generated X-ray energy, which is a tube voltage of an X-ray generator, is varied based upon a measured thickness of a plate to be measured, so as to keep the quality correction value at a prescribed value. CONSTITUTION:An arithmetic processing unit 6 receives as an input a target thickness T set in a target value setting unit 9 and computes a reference quality conversion plate thickness T' by a formula I, together with a quality correction value N determined in accordance with the quality of a plate 12 to be measured. Moreover, the unit 6 sets an X-ray tube voltage corresponding to the conversion plate thickness T' by a tube voltage table, using the relationship between a reference quality conversion plate thickness measured beforehand and the x-ray tube voltage. Thereafter, an X-ray transmitted through the plate 12 to be measured is transduced into an electric signal corresponding to the dose thereof by a radiation detector 3 and inputted to the unit 6 through a preamplifier 4 and an A/D converter 5. The unit 6 computes a reference quality conversion plate thickness TM' corresponding to the input signal, determines a measured plate thickness TM from a formula II by using the quality correction value N, and outputs TM as a measurement output 8 through a D/A converter 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an X-ray thickness meter that measures the thickness and density of a substance using X-rays.

(Prior art) Radiation thickness gauges utilize the fact that when radiation passes through a material, the amount of attenuation corresponds to the thickness of the material.The radiation thickness meter is a non-contact, high-precision, fast-response measurement method. Because of this, it is widely used in ferrous and non-ferrous manufacturing lines.

Among radiation thickness gauges, X-ray thickness gauges that use X-rays as radiation can produce a large amount of radiation, so they can always perform measurements with high precision and fast response. There are several types of X-ray thickness measurement methods; one example is the device shown in Japanese Patent No. 1249848.

In these X-ray thickness gauges, the measurement of the object to be measured is performed by comparing the measurement with a reference plate built into the device or by calibrating the object in advance using a reference material. In other words, it is measured relative to the standard. By the way, the amount of attenuation of radiation in a substance is determined by the type of substance (element) and the energy of the radiation. Therefore, when the type of the object to be measured is different from the reference material, an error occurs in the measured value of the thickness gauge. This is inconvenient for measuring alloys and the like.

For this reason, for radiation thickness gauges, a reference material is determined and
This calibrates the thickness gauge, and if the material to be measured differs from the reference material, determine a correction value that corresponds to the type (elemental composition) of the material to be measured, and apply this correction value to the thickness gauge in advance. This allows for correction and accurate measurements. As the standard substance, pure substances are usually used, for example, pure iron for steel measurement and pure aluminum for aluminum measurement. When measuring an alloy, the correction value is determined by calculating the correction value in advance from the elemental components or by calculating the correction value using an actual thickness gauge.

(Problems to be Solved by the Invention) However, conventional X-ray thickness gauges have disadvantages due to the fact that X-rays have distributed energy. it is,
The problem is that the correction value for the alloy is not a constant value for each type of alloy, but is converted depending on the measured plate thickness.

An example of this is shown in FIG. This is a graph of the thickness of an alloy plate to be measured and correction values in the X-ray thickness test for aluminum measurement. As shown in this figure, it can be seen that the correction value changes greatly depending on the plate thickness. Therefore, it is necessary to change the correction value depending on the thickness of the object to be measured. An X-ray thickness meter separates X-rays [Due to energy, it is difficult to determine this correction value from the constituent elements of the alloy, and the correction value must be determined by actual measurement using an alloy plate of known thickness. This requires a great deal of effort, and the correction value must also be determined based on the plate thickness, which poses a major problem in use in actual production lines.

In actual production lines, especially rolling lines for aluminum, stainless steel, copper alloys, etc., a wide variety of alloy plates are rolled and manufactured, so determining the material correction value described above requires extremely complex processing. .

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the inconvenience that material correction changes depending on the thickness of the measured plate when measuring alloy materials using a conventional X-ray thickness meter.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention emits X-rays to an object to be measured, and measures the thickness of the object by transmitting the X-rays. The X-ray thickness meter includes an X-ray generator that emits an X-ray beam, a radiation detector system that generates an electrical signal corresponding to the transmitted radiation ω, a means for calculating the thickness of the object to be measured using this electrical signal, and a target value setter for setting the target plate thickness and material of the object to be measured; a means for determining the X-ray tube voltage from the setting data of the target value setter; The present invention provides an X-ray thickness meter that measures the thickness of an object to be measured by changing the X-ray tube voltage according to the plate thickness and keeping the material correction value constant.

(Function) With this configuration, X
By changing the tube voltage of the ray generator, that is, the generated X-ray energy,
The material correction value is now kept at a constant value.

(Example) FIG. 2 shows an embodiment of the X-ray thickness meter of the present invention.

The X-ray thickness meter of the present invention includes an X-ray generator 1 that emits an X-ray beam, a built-in reference plate 2 for calibrating the device, and receiving X-rays transmitted through the built-in reference plate 2 or the plate to be measured 12. an arithmetic processing device 6 comprising a radiation detector 3 that generates an electrical signal corresponding to the dose, a preamplifier 4 that amplifies the output signal of the radiation detector 3, an A/D converter 5, a D/A converter 7, etc.;
The target value setter 9 sets the measurement center value of the device, that is, the target thickness value of the plate 12 to be measured, and the X-ray tube voltage of the X-ray generator 1 is controlled and stabilized according to instructions from the arithmetic processing unit 6. , an X-ray control circuit 10 that sets the X-ray tube voltage, and the like.

The program of the arithmetic processing unit 6 includes a program that makes the X-ray tube voltage correspond to the reference material thickness calculated from the material correction value determined by the target thickness of the plate to be measured and the material of the plate to be measured, The target plate thickness value and material correction value set in the target value setter 9 are read, the reference material plate thickness is calculated, the X-ray tube voltage corresponding to the value is determined, and the X-ray control circuit 10 is commanded to It includes a program for setting the X-ray tube voltage of the ray generator 1. This correspondence between the reference material plate thickness and the X-ray tube voltage is characterized in that the material correction value determined for one material (alloy or substance other than the reference material) is made so that it does not change depending on the measured plate thickness. do.

Next, the operation of measuring the thickness of a material different from the reference material using the apparatus configured as described above will be explained.

The arithmetic processing device 6 inputs the target thickness T set in the target value setter 9, and calculates the reference material equivalent plate thickness T' using equation (1) together with the material correction value N determined by the material of the plate 12 to be measured.
Calculate.

T"=T (1+N/'too)...(1
) Here, T-: Standard material conversion plate thickness T: Target thickness N: Material correction value Furthermore, the arithmetic processing unit 6 determines the X-ray tube voltage corresponding to T' from the tube voltage table, and determines the X-ray tube voltage corresponding to T'. Set the X-ray tube voltage by

The determination of the X-ray tube voltage based on the tube voltage table is performed using the relationship between the reference material equivalent plate thickness and the X-ray tube voltage, which are obtained through preliminary measurements. Figure 3 shows the relationship between the standard material equivalent plate thickness and the X-ray tube voltage. X1 to X3 in the figure are the X-ray tube voltages corresponding to the reference material equivalent plate thicknesses T1 to T3, which were determined in advance by actual measurements, and the points are approximated by linear approximation or other methods. In the figure, the X-ray tube voltage X corresponding to the reference material equivalent plate thickness T is determined by linear approximation between Xl and x2.

After setting the X-ray tube voltage, the X-rays that have passed through the board to be measured are exchanged by the radiation detector 3 into electrical signals corresponding to the dose, and then processed via the preamplifier 4 and A/D converter 5. It is input into the device 6. The arithmetic processing unit 6 calculates the standard material equivalent plate thickness TH' corresponding to the input signal, and calculates the measured plate thickness TM from equation (2) using the material correction value N determined by the material.
Determine.

TM = TH"/ (1+N/100) ... (2
) TE is output from the D/A converter 7 to the outside as a measurement output 8.

Note that a tube voltage table is stored for each material of the plate to be measured, and a code representing the type of material is associated with each material. When setting the target plate thickness in the target value setter 9, by setting the code corresponding to the material, the corresponding tube voltage table is automatically selected, and the X-ray tube voltage is determined based on the target plate thickness. By adding a function to set a code indicating the material to the target value setting device 9, the setting operation of the thickness gauge can be easily performed.

[Effects of the Invention] Therefore, with the configuration of the embodiment as described above, it is no longer necessary to determine the material correction value for each target plate thickness for the same material, and the setting operation on the target value setting device 9 of the thickness gauge is simplified. becomes easier. Furthermore, the data management of a huge amount of material correction values has the effect of facilitating data management, such as one material correction value for each measured material.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram for explaining one embodiment of the present invention, Figure 2 is a characteristic diagram showing the relationship between plate thickness and X-ray tube voltage, and Figure 3 is a characteristic diagram showing the relationship between plate thickness and material correction. It is a diagram.

Claims (1)

[Claims] An X-ray thickness meter that emits X-rays to a measured object and measures the thickness of the measured object based on the amount of transmitted radiation uses an X-ray generator that emits an X-ray beam and an electrical signal that corresponds to the amount of transmitted radiation. A radiation detector system that generates radiation, a means for calculating the thickness of the object to be measured based on this electric signal, a target value setting device for setting the target thickness and material of the object to be measured, and an X-ray detection system based on the setting data of the target value setting device. It is equipped with means for determining the tube voltage and an X-ray control circuit that sets the tube voltage of the X-ray generator to the determined X-ray tube voltage value, and changes the X-ray tube voltage in accordance with the plate thickness, and calculates the material correction value. An X-ray thickness meter that measures the thickness of the object by keeping it constant.