JP2019158688A - Magnetic powder inspection device and magnetic powder inspection method - Google Patents

Abstract

To inspect a state of an inspection object indirectly by measuring a magnetic field generated from magnetic powder that can be mixed into a sample regardless of a shape of a vessel for storing a highly viscous sample used as a lubricant of the inspection object.SOLUTION: In a state in which a semi-cured sample used as a lubricant of an inspection object is drawn out to uniformize a thickness of the sample by using a stretching mechanism, a magnetic field is applied to magnetic powder mixed into the sample by using an excitation mechanism, and a magnetic signal generated from the magnetic powder is detected by using a magnetic sensor. A signal analyzer calculates the amount of magnetic powder on the basis of the magnetic signal and displays it on a data display part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic powder inspection apparatus and a magnetic powder inspection method, and more particularly, to a magnetic material relating to a technique for indirectly inspecting the degree of deterioration of a bearing by detecting the amount of magnetic powder mixed into the grease of the bearing due to wear or the like. It is suitable for application to a powder inspection apparatus.

  The bearing is mounted on a motor or axle of a power device, and has an effect of smoothly rotating the shaft while receiving the load of the operation target and reducing energy loss due to friction. Many lubricants are used for the purpose of improving the rotational performance of bearings, and liquid oily agents and semisolid lubricants (hereinafter referred to as “grease”) are widely used. When the bearing rotates, friction occurs due to the metal rubbing against each other, but the metal surface is covered with an oil film of grease, so that the bearing can be smoothly rotated. However, even if the lubricating performance is maintained by the grease, the bearing may be damaged by a long-time rotation operation or improper control management. As a typical damage, a flaking phenomenon is known in which the raceway surface of the bearing and the surface of the transfer body peel off on the scale. In bearings where flaking occurs, magnetic wear powder is mixed in the lubricant, so by measuring the amount of this magnetic powder, the degree of bearing flaking and damage can be indirectly evaluated. Can do.

  As a technique for indirectly evaluating the state of a bearing, for example, in Patent Document 1, a pair of excitation coils connected in series are arranged so that the magnetic fields of the respective excitation coils face each other, and the pair of excitation coils Measurement to detect the induced voltage induced in the detection coil by arranging the detection coil and iron core at the position where the combined magnetic field due to the magnetic field becomes zero, and making it possible to insert and remove the sample mixed with magnetic powder in one excitation coil Means are disclosed (see Patent Document 1).

Japanese Patent No. 3377348

  However, in the measurement means described above, since it is necessary to insert the grease sample into the central part of a pair of exciting coils or the like connected in series, it is necessary to store the grease sample in a small tubular container. Generally, since a grease sample is semi-solid and has low fluidity, it is difficult to accommodate a small-diameter tubular container so as not to contain bubbles. On the other hand, when the diameter of the container is increased, it is necessary to increase the coil diameter, and there is a problem that the detection unit of the inspection apparatus is enlarged.

  The present invention has been made in consideration of the above points, and indirectly measures the state of the inspection object by measuring the magnetic field generated from the magnetic powder that can be mixed in the highly viscous sample used as the lubricant for the inspection object. It is intended to propose a magnetic powder inspection apparatus and a magnetic powder inspection method that can inspect the above.

  In order to solve such a problem, in the present invention, an extension mechanism that stretches a semi-solid sample used as a lubricant for an inspection object to make the thickness of the sample uniform, and a magnetic field applied to the magnetic powder mixed in the sample An excitation mechanism for applying a magnetic field, a magnetic sensor for detecting a magnetic signal generated from the magnetic powder, a signal analyzer for calculating the amount of the magnetic powder based on the magnetic signal, and the signal analyzer And a data display unit for displaying the amount of magnetic powder.

  In the present invention, an extension step is used to extend a semi-solid sample used as a lubricant for an inspection object to make the thickness of the sample uniform, and an excitation mechanism is used to apply the sample. An excitation step of applying a magnetic field to the magnetic powder mixed in, a magnetic detection step of detecting a magnetic signal generated from the magnetic powder using a magnetic sensor, and a signal analyzer, based on the magnetic signal It has a signal analysis step for calculating the amount of magnetic powder, and a data display step for displaying the amount of magnetic powder calculated by the signal analyzer on a data display unit.

  According to the present invention, regardless of the shape of a container for containing a highly viscous sample used as a lubricant for an inspection object, a magnetic field generated from magnetic powder that can be mixed into the sample is measured and indirectly measured. The state of the inspection object can be inspected.

It is a perspective view which shows the structural example of the magnetic powder inspection apparatus which concerns on this Embodiment. It is a figure which shows an example of the adjustment method of the height of the roller as an example of an extension mechanism regarding the magnetic powder inspection apparatus which concerns on this Embodiment. It is a circuit diagram which shows the structural example of the magnetic powder inspection apparatus shown in FIG. It is a flowchart which shows an example of the magnetic powder inspection method which concerns on this Embodiment. It is a figure which shows an example of the output signal waveform of a magnetic sensor in the magnetic powder inspection method which concerns on this Embodiment, and the relationship between the output signal of a magnetic sensor, and magnetic powder weight.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) System configuration according to the present embodiment FIG. 1 shows a configuration example of a magnetic powder inspection apparatus 1 according to the present embodiment. In the illustrated example, an example of a state in which a grease sample 2 as an example of a sample used together with a bearing as an example of an inspection object is installed in the magnetic powder inspection device 1 is shown. The magnetic powder inspection apparatus 1 includes an extension mechanism including a height adjustment screw 5, an adjustment plate 20, a roller 4, and a sample table 3, and further includes a magnetic sensor 6, a magnet 7, a power supply circuit unit 8, and a data display unit 9. ing.

  The sample stage 3 is made of, for example, a nonmagnetic material, and a grease sample 2 as an example of a semi-solid sample is disposed. The semi-solid form mentioned here is an object that is not a complete liquid or solid but has a certain high viscosity, and when it is stored in a predetermined container, bubbles are mixed into the container together with the sample according to the viscosity. It represents the substance in the form of Further, the grease sample 2 is delivered by a delivery mechanism (not shown) while being placed on the sample stage 3.

  The grease sample 2 is in a state in which it is plasticized by pressure applied from the outside of the container by being accommodated in a container made of a flexible non-magnetic material, for example, a plastic bag material.

  The height adjusting screw 5 is a screw for adjusting the height of the roller 4 from the sample stage 3 in order to make the thickness of the grease sample 2 constant. The roller 4 is rotated and moved while its outer peripheral surface is in contact with the upper surface of the grease sample 2, thereby uniformizing the thickness of the grease sample 2 in the direction perpendicular to the surface of the sample table 3.

  The magnetic powder that can be mixed into the grease sample 2 is magnetized by the magnet 7. The generated magnetic field is detected by the magnetic sensor 6. The power supply circuit unit 8 performs power supply and operation control to the magnetic sensor 6 and the data display unit 9.

  FIG. 2 is a diagram illustrating a configuration example of the extension mechanism 21 that adjusts the thickness of the grease sample 2. 2A shows an example of the shape of the adjustment plate 20, and FIG. 2B shows a diagram showing a configuration example in which the adjustment plate 20 and the roller 4 are installed. 2A, the upper side is a top view of the adjustment plate 20, and the lower side is a side view of the adjustment plate 20 (corresponding to the direction of the adjustment plate 20 shown in FIG. 2B). The adjustment plate 20 (t = 0.5 to 30 mm) having a thickness different every 0.5 mm has a substantially rectangular notch formed on one of the four side surfaces. A screw portion of the height adjusting screw 5 is inserted into the notch.

  As a method of adjusting the height of the roller 4, the adjustment plate 20 shown in FIG. 2B is installed on the upper portion of the roller 4, and the position of the adjustment plate 20 is fixed with the height adjustment screw 5. The height of the roller 4 is adjusted in the vertical direction (perpendicular to the surface of the sample table 3) using the height adjusting screw 5 according to the thickness of the adjusting plate 20, and the thickness of the grease sample 2 is adjusted to a desired value. It is adjustable.

  For the power source of the roller 4, for example, manual rotation or automatic rotation by motor control can be employed.

  FIG. 3 is a block diagram showing an example of a circuit configuration of the magnetic powder inspection apparatus 1 shown in FIG. The magnetic powder inspection apparatus 1 includes a magnetic sensor 6, a power supply circuit unit 8, a magnetic sensor amplifier 11, and a filter circuit 12.

  The power supply circuit unit 8 includes a power supply 10, an A / D converter 13, a signal collector 14, a signal analyzer 15, and a data display unit 9.

  The magnetic sensor 6 is a sensor that outputs the magnitude of a magnetic field generated from the magnetic powder as an electric signal when the magnetic powder mixed in the grease sample 2 is magnetized by the magnet 7. The magnetic sensor 6 is, for example, a TMR (Tonnel Magneto Resistive) sensor, an AMR (Anisotropic Magneto Resistive) sensor, a GMR (Giant Magneto Resistive effect) sensor, or a detection coil.

  One magnetic sensor 6 may be used, but two or more, for example, may be used, and output signals may be output for a plurality of locations in the grease sample 2. In this way, by averaging these output signals, the amount of magnetic powder contained in the grease sample 2 can be detected with higher accuracy.

  The magnet 7 is used for magnetizing the magnetic powder mixed in the grease sample 2. As the magnet 7, for example, a bias magnet that operates the magnetic sensor 6 in a linear region and generates a DC magnetic field can be used. Instead of the magnet 7 as an excitation mechanism, for example, an excitation coil that forms an alternating magnetic field having a frequency of 1 Hz to 10 MHz can be used instead.

  The magnetic sensor amplifier 11 amplifies the output signal from the magnetic sensor 6. The filter circuit 12 is a circuit that outputs an analog signal that passes through a desired frequency region among the output signals amplified by the magnetic sensor amplifier 11.

  The A / D converter 13 converts the analog signal output from the filter circuit 12 into a digital signal and outputs the digital signal to the signal collector 14. The signal collector 14 is a memory or a storage, for example, and stores the digital signal output from the A / D converter 13.

  The signal analyzer 15 includes, for example, a CPU (Central Processing Unit), and the CPU executes a signal analysis program to perform signal analysis. The data display unit 9 includes, for example, an input / output interface, a liquid crystal display, and an input device (button, encoder), and displays the result analyzed by the signal analyzer 15.

  Hereinafter, a magnetic powder inspection method as an operation example of the magnetic powder inspection apparatus 1 according to the present embodiment will be described. First, as an example, a grease sample 2 as a semi-solid lubricant collected from a bearing (not shown) is placed on the sample table 3, and the grease sample 2 is arranged immediately below the roller 4 whose height has been adjusted in advance as described above. Then, the thickness of the grease sample 2 is made uniform by stretching the grease sample 2 by the rotational movement of the roller 4.

  Next, the sample table 3 is disposed at a position close to the magnet 7 and the magnetic sensor 6, and the grease sample 2 is moved together with the sample table 3, thereby passing the upper surface of the magnet 7 and the magnetic sensor 6. At this time, the magnetization of the grease sample 2 by the magnet 7 and the magnetic field detection by the magnetic sensor 6 are simultaneously performed.

  The output of the magnetic sensor 6 is amplified by the magnetic sensor amplifier 11, and after the frequency component regarded as a noise signal is removed by the filter circuit 12, it is output as a desired signal component. Here, the frequency component regarded as a noise signal is, for example, a commercial frequency component of a signal mixed from a power source or an external environmental magnetic field, or a low frequency component of 1 to several Hz. The output signal of the filter circuit 12 is stored in the signal collector 14 via the A / D converter 13.

  The signal output from the signal collector 14 is subjected to arithmetic processing in the signal analyzer 15 to analyze the relationship between the signal measured by the magnetic sensor 6 and the concentration of the magnetic powder. Thereby, the density | concentration of the magnetic powder of the grease sample 2 is calculated.

  Furthermore, the signal analyzer 15 determines the deterioration state of the bearing based on the concentration of the magnetic powder thus calculated. Here, the bearing may be damaged by a flaking phenomenon due to a long-time rotation operation or improper control management even if the lubricating performance is maintained by grease.

  The data display unit 9 displays the magnetic powder concentration calculated by the signal analyzer 15. Bearings with flaking are mixed with magnetic wear powder in the lubricant, so measuring the amount of this magnetic powder can indirectly evaluate the degree of bearing flaking and damage. it can. Thereby, the data display part 9 displays the determination result of the deterioration state of a bearing further in addition to the density | concentration of magnetic powder.

  FIG. 4 is a flowchart illustrating an example of a procedure from signal detection to display of a determination result in the present embodiment. In the present embodiment, a grease sample 2 having a known magnetic powder concentration is measured in advance, and a signal representing the measurement result and a calibration curve are created from the known concentration.

  After preparing the calibration curve in this way, the grease sample 2 whose magnetic powder concentration is unknown is measured, and a signal representing the measurement result is compared with the calibration curve prepared in advance, and the grease sample 2 whose concentration is unknown is compared. Calculate the concentration of magnetic powder.

  In FIG. 4, steps S30 to S37 show a thickness equalization process, a signal measurement process, and a calibration curve creation process related to the grease sample 2 containing a magnetic powder having a known concentration.

  First, the grease sample 2 mixed with a known concentration of magnetic powder is placed on the sample stage 3 (step S30). Next, the height of the roller 4 is adjusted with the height adjusting screw 5, and the adjusting plate 20 suitable for the thickness is installed so that the grease sample 2 has a desired thickness (step S31). The roller 4 rotates on the upper surface of the grease sample 2 (step S32), and equalizes the thickness of the grease sample 2 on the sample table 3 (step S33).

  The grease sample 2 having a uniform thickness is placed close to the top surfaces of the magnet 7 and the magnetic sensor 6 while being placed on the sample table 3 (step S34). Thereby, the grease sample 2 is magnetized by the magnet 7, and the magnetic field generated from the magnetic powder is detected by the magnetic sensor 6 (step S35).

  The magnetic signal detected by the magnetic sensor 6 is collected by the signal collector 14 through the signal processing of the magnetic powder inspection apparatus 1. A calculation process is performed on the signal input to the signal analyzer 15 (step S36).

  In the above-described procedure, since a plurality of grease samples having different concentrations are targeted, steps S30 to S36 are repeatedly executed. When the signal processing of the target sample is completed, the signal analyzer 15 analyzes the relationship between such a signal and the known concentration of the magnetic powder, and creates a calibration curve (step S37).

  On the other hand, steps S37 to S43 are processing procedures for the grease sample 2 whose magnetic powder concentration is unknown.

  First, the grease sample 2 mixed with a known concentration of magnetic powder is placed on the sample stage 3 (step S38). Next, the roller 4 rotates on the upper surface of the grease sample 2 to make the thickness of the grease sample 2 uniform (step S39).

  The grease sample 2 having a uniform thickness is placed close to the upper surfaces of the magnet 7 and the magnetic sensor 6 in a state of being placed on the sample stage 3 (step S40). Thereby, the grease sample 2 is magnetized by the magnet 7 and a magnetic signal is detected by the magnetic sensor 6 (step S41).

  The magnetic signal is subjected to signal processing of the magnetic powder inspection apparatus 1, and is collated with the calibration curve created in step S37 in the signal analyzer 15 (step S42), and the magnetic powder concentration of the sample is calculated (step S43).

  The signal analyzer 15 compares the magnetic powder concentration calculated as described above with a preset signal threshold value indicating deterioration of the bearing, and when the magnetic powder concentration is equal to or higher than the threshold value, the data display unit 9 A warning indicating deterioration of the bearing is displayed (step S44).

By the way, it is verified whether or not the calibration curve of the magnetic powder can be obtained by calculating the weight of the magnetic powder from the signal intensity. First, magnetic powder whose weight was previously known was mixed in the grease sample 2 and its magnetic signal was measured. The weight of the magnetic powder is 58 to 260 μg (concentration 1 to 4.5 mg / cm ³ ) per 58 mm ³ capacity, and 58 to ³ so that the concentration is constant at 1 mg / cm ^3. Two types of samples, Sample B, in which 260 μg of magnetic powder was added to 58 to 260 mm ³ were prepared.

  The sample A is magnetized using a magnet after the thickness is made uniform, for example, 2 mm. On the other hand, the sample B is magnetized using a magnet with a constant thickness and a non-uniform aspect such as 2 mm to 8 mm, for example.

  In the present embodiment, a TMR sensor is employed as the magnetic sensor 6, and the sample A and the sample B are magnetized by a bias magnet that is mounted to operate the TMR sensor in a linear region. The magnetic force of this bias magnet is about 100 mT (Tesla).

  The magnetized sample A and sample B are arranged on the upper surface of the magnetic sensor 6 on the sample stage 3, and each magnetic signal was detected using the magnetic sensor 6. At this time, since the height of the sample stage 3 is 1 mm, for example, the distance between the magnetic sensor 6 and each of the samples A and B is 1 mm. The detected magnetic signal has a gain of 1000 times by the magnetic sensor amplifier 11, passes a signal in a band of 1 to 40 Hz by the filter circuit 12, and is input to the A / D converter 13 and the signal collector 14. In this way, magnetic signals from the samples A and B were obtained.

  FIG. 5A shows a waveform of a magnetic signal acquired from the sample A. The signal intensity of sample A was calculated based on an amplitude value Vpp composed of a maximum value and a minimum value of the waveform. As shown in FIG. 5A, when the weight of the magnetic powder is 87 μg, the magnetic signal is 0.25 Vpp, and when the weight of the magnetic powder is 260 μg, the magnetic signal is 0.77 Vpp. Therefore, it can be seen that the amplitude value of the signal waveform increases as the weight of the magnetic powder increases.

  FIG. 5 (B) shows an example of a calibration curve showing an example of the relationship between the magnetic signal relating to each of the samples A and B and the weight of the magnetic powder. In the graph of FIG. 5B, in the sample A, the signal intensity increases as the weight of the magnetic powder increases, and the correlation coefficient R2 = 0.97. On the other hand, in the sample B, even if the weight of the magnetic powder increases, the signal intensity does not always increase, and it is difficult to calculate the weight of the magnetic powder from the signal intensity. Therefore, as shown in the sample A, it is understood that the calibration curve of the magnetic powder can be acquired by obtaining the signal from the magnetic sensor 6 after uniformizing the thickness of the sample.

(2) Other Embodiments The above embodiment is an example for explaining the present invention, and is not intended to limit the present invention only to these embodiments. The present invention can be implemented in various forms without departing from the spirit of the present invention. That is, the present embodiment is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail in order to easily understand the present invention. Yes, and not necessarily limited to those having all the configurations described. A part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is also possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  A part or all of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware such as an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by a processor interpreting and executing a program that realizes each function. Information such as programs, tables, and files for realizing each function may be stored in a recording device such as a memory, a hard disk, or an SSD (Solid State Drive), or a recording medium such as a flash memory card or a DVD (Digital Versatile Disk). it can. The data obtained by executing the program can be transmitted to a remote site online and a warning can be issued using a wired or wireless communication technology.

  In the present embodiment described above, the control lines and information lines indicate what is considered necessary for the explanation, and not all control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

Examples of modifications of the present embodiment include the following (A) to (C).
(A) The extension mechanism for making the thickness of the grease sample 2 uniform is not limited to that by the rotation of the roller 4. For example, a spacer having a predetermined thickness is sandwiched between two plates. The sample 2 may be compressed and stretched from both sides to be uniform to a predetermined thickness.
(B) A sample for generating a calibration curve is not limited to semi-solid grease, and a fluid lubricant may be used.
(C) The processing of steps S30 to S37 described above need not be performed every time for each unknown sample, and may be executed once at the first measurement to set a calibration curve.

  The present invention can be widely applied to a magnetic powder inspection apparatus that indirectly inspects the degree of deterioration damage of a bearing by detecting the amount of magnetic powder mixed into the grease of the bearing due to wear or the like.

  DESCRIPTION OF SYMBOLS 1 ... Magnetic powder inspection apparatus, 2 ... Grease sample, 3 ... Sample stand, 4 ... Roller, 5 ... Height adjustment screw, 6 ... Magnetic sensor, 7 ... Magnet, 8 ... Power supply circuit part , 9: Data display section, 10: Power supply, 11: Magnetic sensor amplifier, 12: Filter circuit, 13: A / D converter, 14: Signal collector, 15: Signal analyzer.

Claims (9)

An extension mechanism that stretches a semi-solid sample used as a lubricant for an inspection object to make the thickness of the sample uniform;
An excitation mechanism for applying a magnetic field to the magnetic powder mixed in the sample;
A magnetic sensor for detecting a magnetic signal generated from the magnetic powder;
A signal analyzer for calculating the amount of the magnetic powder based on the magnetic signal;
A data display unit for displaying the amount of the magnetic powder calculated by the signal analyzer;
A magnetic powder inspection apparatus comprising: The signal analyzer is for a known sample mixed with a known amount of magnetic powder.
A calibration curve is created from the magnetic signal and the amount of magnetic powder of the known sample detected by the magnetic sensor, and the magnetic signal and the calibration from an unknown sample whose amount of magnetic powder is unknown detected by the magnetic sensor The magnetic powder inspection apparatus according to claim 1, wherein the amount of magnetic powder mixed in the unknown sample is calculated based on a line. The signal analyzer is
The magnetic powder inspection apparatus according to claim 1, wherein the state of the bearing is determined from the amount of magnetic powder contained in the sample. The data display unit
The magnetic powder inspection apparatus according to claim 1, wherein a state of a bearing as the inspection object is displayed based on the amount of the magnetic powder calculated by the signal analyzer. The extension mechanism is
The magnetic powder inspection apparatus according to claim 1, wherein the sample is stretched by rotation of a roller. The extension mechanism is
The magnetic powder inspection apparatus according to claim 1, wherein the sample is stretched by two plates sandwiching a spacer having a predetermined thickness. The excitation mechanism is
The magnetic powder inspection apparatus according to claim 1, wherein a DC magnetic field generated from a bias magnet of the magnetic sensor is formed. The excitation mechanism is
The magnetic powder inspection apparatus according to claim 1, wherein an alternating magnetic field having a frequency of 1 Hz to 10 MHz is formed. Using a stretching mechanism, stretching a semi-solid sample used as a lubricant for the test object to make the thickness of the sample uniform; and
An excitation step of applying a magnetic field to the magnetic powder mixed in the sample using an excitation mechanism;
A magnetic detection step of detecting a magnetic signal generated from the magnetic powder using a magnetic sensor;
A signal analysis step of calculating the amount of the magnetic powder based on the magnetic signal using a signal analyzer;
A data display step for displaying the amount of the magnetic powder calculated by the signal analyzer on a data display unit;
A magnetic powder inspection method characterized by comprising:

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