JPS5926897B2 - Fluorescent magnetic particle concentration measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring the concentration of fluorescent magnetic particles in a fluorescent magnetic particle test solution used for fluorescent magnetic particle inspection.

Fluorescent magnetic particle flaw detection is aimed at inspecting for surface flaws on the inspected material, and involves magnetizing the inspected material to generate leakage magnetic flux at the surface flaws, and then spraying a test liquid containing fluorescent magnetic particles suspended in it. Whether the flaw is harmful or not is determined based on the amount of fluorescent magnetic powder per unit length that is magnetically attracted to the surface flaw due to leakage magnetic flux.

That is, the depth of the surface flaw is determined based on the amount of fluorescent magnetic powder magnetically attached to the surface flaw.

Therefore, when a test liquid is sprayed at a constant flow rate for a certain period of time onto a surface flaw that generates a certain amount of leakage magnetic flux, the amount of fluorescent magnetic particles magnetized to the surface flaw is equal to the fluorescent magnetic powder of the test liquid. Since it is approximately proportional to the concentration, if the concentration of fluorescent magnetic particles is higher or lower than the standard value, a harmful deep scratch will be determined to be a harmless shallow scratch, or a harmless shallow scratch will be determined to be a harmful deep scratch. Therefore, it was necessary to keep the fluorescent magnetic powder concentration constant. In addition, among the fluorescent magnetic particles added to the test solution, the fluorescent substance and magnetic particles are combined and are effective for fluorescent magnetic particle inspection (hereinafter referred to as
Effective fluorescent magnetic powder) and fluorescent material that is useless for fluorescent magnetic particle inspection due to the manufacturing technology of fluorescent magnetic powder (hereinafter referred to as ineffective fluorescent magnetic powder) coexist, and their ratio is approximately the same. . For this reason, when a test liquid is used, effective fluorescent magnetic particles are magnetically attached to the material to be inspected and taken out of the test liquid, but ineffective fluorescent magnetic particles, which are non-magnetic substances, are magnetically attached to the material to be inspected. During use, the ratio of effective and ineffective fluorescent magnetic particles in the testing liquid becomes different. Therefore, it is necessary to remove the ineffective fluorescent magnetic particles in the test liquid and measure only the concentration of the effective fluorescent magnetic particles. Conventionally, the test solution was first irradiated with ultraviolet rays to measure the amount of light emitted from both effective and ineffective fluorescent magnetic particles, and then the effective fluorescent magnetic particles were precipitated using a magnet, and the ineffective fluorescent magnetic particles were separated from the active fluorescent magnetic particles. There is a method that measures the effective fluorescent magnetic particle concentration in the test solution by measuring the amount of luminescence and subtracting the latter value from the former.

However, when first measuring both effective and ineffective fluorescent magnetic particles, not only the effective fluorescent magnetic particles but also the ineffective fluorescent magnetic particles naturally precipitate over time.
Therefore, the measured value was not determined, and the measurement error was about 30%. Furthermore, when the effective fluorescent magnetic powder is precipitated using a magnet, the effective fluorescent magnetic powder gradually precipitates, and it takes about 10 minutes or more for most of it to precipitate, resulting in the disadvantage that the measurement takes a long time.

Further, during the time period for precipitating the effective fluorescent magnetic powder, a portion of the ineffective fluorescent magnetic powder also precipitated, making it impossible to accurately measure the amount of effective fluorescent magnetic powder.

In addition, a low-pressure mercury lamp is used as a light source for irradiating ultraviolet rays to cause fluorescent magnetic powder to emit light.Low-pressure mercury lamps have an ultraviolet radiation amount of about 50 (fl) for an ambient temperature change of 2'C±10°C. Since the amount of ultraviolet rays varies, it is generally considered that the amount of ultraviolet rays can be kept constant by measuring the amount of ultraviolet rays and feeding it back to the power source of the low-pressure mercury lamp. It has a positive characteristic up to .degree. C., and becomes a negative characteristic above that temperature. Therefore, with this method, it is not possible to obtain a constant amount of ultraviolet rays unless the ambient temperature is within a certain narrow range.

In addition, when a low-pressure mercury lamp deteriorates and the amount of ultraviolet rays decreases, the electric power applied to the low-pressure mercury lamp increases further to increase the amount of ultraviolet rays, which causes the lamp to deteriorate more quickly. Had to have. SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus capable of accurately measuring the concentration of fluorescent magnetic particles in a fluorescent magnetic particle test solution used for fluorescent magnetic particle inspection, while eliminating the drawbacks of the conventional apparatus.

Next, the present invention will be described in detail with reference to embodiments of the present invention based on the accompanying drawings.

In FIG. 1, a test liquid container 1 contains a fluorescent magnetic powder test liquid 1a, has a rectangular shape, and is made of a material that transmits excitation light and imperial light.

The storage cup 3 has a structure in which the test liquid container 1 is housed in a fixed position with respect to the slits 5 and 6. The heater 2 is attached to the container 3, and heats the test liquid 1a to prevent effective fluorescent magnetic particles and ineffective fluorescent magnetic particles from spontaneously settling in the test liquid 1a in the test liquid container 1. The excitation coil 4 is attached to the storage container 3 and the test liquid 1
This is for magnetically attaching the effective fluorescent magnetic powder, which is the magnetic substance in a, to the bottom of the test liquid container 1.

The excitation light source 7 strongly emits ultraviolet light having a wavelength of about 3650λ, and is disposed within the excitation light source case 10. The optical filter 18 has a wavelength of about 365, excluding visible light.
It has the characteristic of transmitting 0λ ultraviolet rays.

The slit 5 is the corner of the test liquid 1a in the test liquid container 1. C
It is attached at a position where excitation light from the IjjJ excitation light source 7 is irradiated. In other words, this configuration is
This is because the excitation light is applied to a very narrow range of the test liquid 1a, which is not affected by the change in the transmission characteristics of the excitation light due to contamination of the test liquid 1a. The photoelectric converter 9 is arranged near the excitation light source 7 within the excitation light source case 10 and detects the amount of excitation light.

The slit 6 is attached to a corner of the container 3 in a direction perpendicular to the irradiation direction of the excitation light, and is located in a range where the attenuation of the excitation light and fluorescent light is not affected by the dirt of the test liquid 1a, that is, the The fluorescent light from the fluorescent magnetic powder in the range A in FIG. 4 is transmitted to the photoelectric converter 11 disposed within the shield case 13. The optical filter 12 has a characteristic of blocking excitation light and transmitting fluorescent light.

FIG. 2 is a side elevational view of the apparatus of FIG.
is attached to the excitation coil 4 to concentrate the magnetic flux generated by the excitation coil 4 on the bottom of the test liquid container 1.

The iron core 14 is made of a magnetic material with no residual magnetism, and can be considered to form an electromagnet together with the excitation coil 4. It is preferable to add an electronic processing circuit as shown in the block diagram in FIG. 3 to the devices shown in FIGS. 1 and 2. In FIG. 3, the dividing circuit 15 detects the amount of excitation light. The photoelectric converter 1 receives electrical signals from the photoelectric converter 9 detecting the amount of fluorescence and the photoelectric converter 11 detecting the amount of fluorescent light.
This is a circuit that divides an electrical signal of 1. The electrical signal from the photoelectric converter 11 is a value obtained by multiplying the fluorescent magnetic powder concentration and the amount of excitation light, and by dividing it by the electrical signal from the photoelectric converter 9, i.e., the amount of excitation light, changes in the amount of excitation light can be calculated. The effect is due to cancellation.

Therefore, only a signal related to the concentration of fluorescent magnetic particles can be extracted regardless of fluctuations in the amount of excitation light. Division circuit 15
A display 16 is provided for receiving the signal and displaying the concentration of fluorescent magnetic particles in the test liquid 1a.

When measuring the fluorescent magnetic particle concentration of the test liquid 1a using the apparatus of this embodiment of the present invention, first, the excitation light source 7, the photoelectric converter 9
, 11, heater 2, divider circuit 15, and display 16 are put into operation.

When the test liquid 1a is put into the test liquid container 1 and the test liquid container 1 containing the test liquid 1a is stored in the container 3, the test liquid 1
a is thermally stirred by a heater 2, and the fluorescent magnetic particles in the test liquid 1a are uniformly suspended without spontaneous precipitation.

Via the optical filter 8 and the slit 5, the excitation light source 7 irradiates the test liquid 1a at the corner of the test liquid container 1 with excitation light, and the effective and ineffective fluorescent magnetic particles at the corner are exposed to the excitation light. Emit light upon excitation.

The photoelectric converter 1 passes through the slit 6 and the optical filter 12.
1 captures the amount of fluorescence only at the corners of the test liquid 1a and converts it into an amount of electricity. The division circuit 15 divides the electrical signal of the photoelectric converter 11 by the electrical signal of the photoelectric converter 9 that detects the amount of excitation light, and calculates the concentration (containing effective fluorescent magnetic powder and ineffective fluorescent magnetic powder).
The electrical signal of the total concentration (hereinafter referred to as the total concentration) is taken out, and the display 1
6 displays the total density.

This total density may be read out or may be stored in a separate storage circuit (not shown). Next, when the excitation coil 4 is operated, the iron core 14
As a result, magnetic flux is generated near the test liquid 1a at the bottom of the test liquid container 1.

The test solution 1a is stirred by the heat of the heater 2, and the effective fluorescent magnetic powder, which is a magnetic material, is circulated to the bottom of the test solution container 1 and is magnetized to the bottom of the test solution container 1, but the non-magnetic material The ineffective fluorescent magnetic particles are not magnetized but are stirred and uniformly suspended in the test liquid.

After a certain period of time, all of the effective fluorescent magnetic particles are magnetically attached to a fixed part of the test liquid container 1. After all the effective fluorescent magnetic particles are magnetized, the concentration of the suspended invalid fluorescent magnetic particles stirred by the heater 2 (hereinafter referred to as the invalid concentration) is read on the display 16.

This reactive concentration may be stored once in a storage circuit.
Next, the effective magnetic particle concentration can be determined by subtracting the invalid concentration from the total concentration. For such subtraction, a separate subtraction circuit (not shown) is provided in conjunction with the storage circuit, and the total concentration value and the reactive concentration are read out from the storage circuit to the subtraction circuit to perform the subtraction operation. It's okay. In order to read the concentration of the reactive component, the time required for all of the effective fluorescent magnetic particles to be magnetized may be measured in advance, and a timer may be used to notify the measurement using a lamp or a buzzer.

In addition, in the case of subtracting the reactive concentration from the total concentration, when the timer operates, the reactive concentration is electrically subtracted from the total concentration electrically stored in the storage circuit, and the effective magnetic particle concentration is displayed. good.

In addition, since the fluorescent magnetic powder added to the test solution contains approximately the same amount of effective fluorescent magnetic powder and ineffective fluorescent magnetic powder, it is necessary to prepare the fluorescent magnetic powder in advance, for example, 0.19/1, 0.2 y/l, etc.・・・・・・
...1f! Test liquids with a fluorescent magnetic particle concentration of /l are prepared, the effective magnetic particle concentrations of these test liquids are measured, and the fluorescent magnetic particle concentration is displayed on the display 16 as 0.19/1 in correspondence with this effective magnetic particle concentration.
, 0.79/l......19/l, so by measuring the effective magnetic particle concentration of the test liquid in use, the fluorescent magnetic powder added to the test liquid can be measured. You can find out how many 9/l it is after conversion.

In the above-described embodiments, a heater was used as the stirrer, but an electromagnetic coil or other stirring device may also be used.

As explained above in the embodiments, the device of the present invention has the following features:
By stirring the test liquid with a stirrer, the fluorescent magnetic particles are uniformly suspended without spontaneous precipitation, firstly, in the measurement of both effective and ineffective fluorescent magnetic particles, measurement errors due to natural precipitation are eliminated, and then In the measurement of ineffective fluorescent magnetic particles,
It is possible to magnetically precipitate only effective fluorescent magnetic powder in a short time without spontaneously precipitating ineffective fluorescent magnetic powder.

Furthermore, the device of the present invention uses a signal proportional to the amount of excitation light from the photoelectric converter 9 to generate an electric signal proportional to the amount of fluorescent light from the photoelectric converter 11, that is, a value obtained by multiplying the fluorescent magnetic particle concentration and the amount of excitation light. By measuring the concentration of fluorescent magnetic particles by dividing , the measured value is made unaffected by fluctuations in the amount of excitation light. Furthermore, the device of the present invention measures the fluorescent light from the fluorescent magnetic particles in the surface layer of the test liquid using the slit 5 and slit 6 =::↓=;:T;:÷〒. Measurement errors due to attenuation of the excitation light and fluorescence light due to the degree of contamination are avoided.

As described above, following the measurement of the total concentration of effective and ineffective fluorescent magnetic particles, only effective fluorescent magnetic particles can be collected at the bottom of the test liquid container 1 by the excitation coil 4, so that the concentration of ineffective fluorescent magnetic particles can be accurately determined. It is something that can be measured.

Conventionally, the measurement errors of the total concentration and the ineffective fluorescent magnetic powder concentration were each about 30%, but by using the apparatus of the present invention, the measurement error was improved to about 5 (F6).

Therefore, by subtracting the invalid fluorescent magnetic particle concentration from the total concentration, it becomes possible to accurately measure the fluorescent magnetic particle concentration in terms of the fluorescent magnetic powder added to the test solution, which is useful for fluorescent magnetic particle inspection. Improved accuracy. Furthermore, the measurement time was 10 minutes with the conventional method, but was shortened to 30 seconds with this device.

In addition, when using an automatic fluorescence flaw detector that automatically detects flaws by receiving fluorescence from fluorescent magnetic particles in the flawed area using a photomultiplier tube, in order to stabilize the flaw detection accuracy, it is necessary to The most important issue is the control of the concentration of fluorescent magnetic particles, and without a device that can accurately measure the concentration of fluorescent magnetic particles, automatic fluorescent flaw detectors cannot be used.
Although this was not practical, it became possible by using the device of the present invention.

[Brief explanation of drawings]

FIG. 1 of the accompanying drawings is a partially sectional plan view schematically showing an embodiment of the present invention, FIG. 2 is a partially sectional elevational view of the apparatus shown in FIG. 1, and FIG. FIG. 4 is a block diagram showing an example of the circuit, and is a diagram showing the detection location of the test liquid in the test liquid container in the present invention. 1...Test liquid container, 1a...Test liquid,
2...Heater, 4...Excitation coil,
5, 6... Slit, 7... Excitation light source, 8, 12... Optical filter, 9, 11...
...Photoelectric converter, 14...Iron core, 15...
...Division circuit, 16...Display unit, A...
...corner.

Claims (1)

[Scope of Claims] 1. A container for containing a predetermined amount of a fluorescent magnetic particle test liquid, and a stirring means for stirring the fluorescent magnetic powder test liquid in the container;
a magnetic attraction means for temporarily exerting a magnetic attraction force on at least a portion of the container; an excitation light source for irradiating the fluorescent magnetic particle test solution in the container with an excitation light beam; and a fluorescent light beam from the fluorescent magnetic particle test solution. What is claimed is: 1. A fluorescent magnetic particle concentration measuring device comprising: measuring means for measuring the amount of . 2. The measuring means includes a first photoelectric converter that receives excitation light from the excitation light source and generates a first electrical signal in response to the excitation light, and a first photoelectric converter that receives the fluorescent light from the fluorescent magnetic powder test liquid and generates a first electric signal in response to the excitation light. a second photoelectric converter that generates a second electrical signal, and a divider that receives the first electrical signal and the second electrical signal and divides the second electrical signal by the first electrical signal; The fluorescent magnetic powder according to claim 1, comprising a calculation circuit and a display for receiving a signal representing the quotient of the division from the dividing circuit and displaying the fluorescent magnetic powder concentration accordingly. Concentration measuring device. 3. The measuring means further includes a storage circuit for storing a signal representing the quotient of the division from the division circuit, and a subtraction circuit for receiving the signal stored in the storage circuit and performing subtraction. The fluorescent magnetic particle concentration measuring device according to claim 2, wherein the display device receives a signal representing the difference between the subtractions from the subtracting circuit and displays the fluorescent magnetic particle concentration accordingly. . 4. The container is made of a material that can transmit excitation light and fluorescent light, and one side of a corner of the container has a first ring that guides the excitation light from the excitation light source to the corner. Optical means is provided, and the other side is provided with a second optical means for guiding the fluorescent light from the corner to the measuring means. The fluorescent magnetic powder concentration measuring device described above. 5. The first optical means comprises an optical filter and slit means that transmit only ultraviolet rays, and the second optical means comprises an optical filter and slit means that transmit only fluorescent rays. Fluorescent magnetic powder concentration measuring device as described in . 6. The fluorescent magnetic powder concentration measuring device according to claim 1, 2, 3, 4, or 5, wherein the stirring means is a heater provided at the lower part of the container. 7. Fluorescent magnetic powder concentration according to claim 1 or 2 or 3 or 4 or 5 or 6, wherein the magnetic attraction means is an electromagnet provided at the lower part of the container. measuring device.