JP6989375B2 - Gate pin inspection device and inspection method as a bearing member for radial gates - Google Patents

Description

The present invention relates to a gate pin inspection device and an inspection method, and more particularly to a gate pin inspection device and an inspection method using an AE (acoustic emission) waveform.

Conventionally, the frictional force of a radial gate bearing member (hereinafter referred to as "gate pin") has been the subject of inspection in the technical standard of structural design (for example, the technical standard of sluice steel pipe). FIG. 11 is a diagram showing the overall configuration of the radial gate 100. With reference to FIG. 11, the radial gate 100 is provided at a water gate or the like that closes the upstream and downstream of the river, and has a door body 103 and a leg 102 that connects the door body 103 and a rotating pin (support portion) 101. including. A take-up wire (not shown) is connected to the door body 103, and by winding the winding wire 103, the door body 103 rotates about the rotation pin 101. However, since the door body 103 is normally closed, the friction of the rotating pin 101 increases over time, resulting in poor movement. As a result, the resistance moment of the leg 102 becomes large during the opening / closing operation, and the leg 102 may buckle, leading to the collapse of the entire radial gate 100. Therefore, it is necessary to periodically inspect the frictional force of the rotating pin 101. In order to evaluate this frictional force, it is necessary to attach a strain gauge to the leg and directly measure the resistance moment. In addition, since the friction of the bearing changes over time, it is necessary to monitor the change regularly.

On the other hand, an apparatus for analyzing a frictional wear phenomenon of a friction member using an AE sensor is disclosed in, for example, Japanese Patent Application Laid-Open No. 2015-25713 (Patent Document 1). According to the same publication, the friction and wear phenomenon analysis device is provided with a pressing device for frictionally contacting the friction member with the rotating member and an urging member for contacting the AE sensor with the friction member 2 in a separate system, whereby the friction of the friction member is provided. There is a description that the contact is surely performed and the AE generated in the friction member is detected with high sensitivity.

Japanese Unexamined Patent Publication No. 2015-25713

Inspecting the frictional force of the conventional gate pin material has a problem that labor cost, scaffolding cost, etc. are incurred, and it takes time and cost. On the other hand, in the past, there was no idea of evaluating a gate pin using an AE sensor.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide an inexpensive and easily gate pin inspection device and method using an AE waveform.

The gate pin inspection device according to the present invention has an AE sensor attached to the gate pin, a waveform acquisition unit that acquires an AE waveform from the AE sensor, and a predetermined DA value obtained based on the waveform acquired by the waveform acquisition unit. It includes an evaluation unit that evaluates the frictional force of the gate pin by using it, and an output unit that outputs the evaluation result of the evaluation unit.

Preferably, the evaluation unit evaluates the frictional force of the gate pin using the RMS value of the waveform acquired by the waveform acquisition unit.

More preferably, the evaluation unit discriminates the frictional force of the gate pin into a plurality of regions by using the AE waveform acquired by the waveform acquisition unit and the RMS value of the AE waveform.

In another aspect of the invention, the gate pin inspection method evaluates the frictional force of the gate pin using a step of acquiring an AE waveform from an AE sensor attached to the gate pin and a predetermined DA value based on the acquired waveform. A step to output an evaluation result and an output step to output the evaluation result are included.

According to the present invention, an AE waveform caused by friction is acquired, and an evaluation value is obtained based on the AE waveform, and the bearing portion is evaluated. There is no need to provide manpower or scaffolding as in the past. As a result, it is possible to provide a gate pin inspection device and an inspection method capable of inspecting the gate pin inexpensively and easily.

It is a block diagram which shows the whole structure of a gate pin inspection apparatus. It is a figure explaining the DA value used for evaluation by an evaluation part. It is a figure which shows the outline of the measurement. It is a figure which shows the friction coefficient measurement result. It is a figure which shows the setting example of a dangerous area. It is a figure which shows the identification index of friction coefficient estimation. It is a figure which shows the identification index of friction coefficient estimation. It is a flowchart which shows the process performed by a control unit. It is a figure which shows the result of applying the identification index to a corroded flat plate. It is a figure which shows the result of applying the identification index to the field measurement data. It is a figure which shows the radial gate.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an overall configuration of a gate pin inspection device according to an embodiment of the present invention. With reference to FIG. 1, the gate pin inspection device 10 includes an AE sensor 15 attached to the gate pin to detect AE data, a waveform acquisition unit 12 for acquiring AE waveform data from the AE sensor 15, and a waveform acquisition unit 12. An evaluation unit 13 that evaluates the degree of friction from the acquired AE waveform, an output unit 14 that outputs the evaluation result of the evaluation unit 13, and a control unit (CPU) that controls the waveform acquisition unit 12, the evaluation unit 13, and the output unit 14. ) And.

Next, the evaluation contents of the evaluation unit 13 will be described. FIG. 2 is a diagram for explaining the AE waveform acquired by the waveform acquisition unit 12. With reference to FIG. 2, the X-axis indicates time (ms) and the Y-axis indicates amplitude (voltage V). Here, the AE waveform is a waveform in which the amplitude gradually increases as shown in the figure, reaches a constant maximum amplitude, and then attenuates. When the AE waveform is input, the time until the maximum amplitude value first exceeds a predetermined threshold value is called the signal rise time.

Here, the amplitude value gives information corresponding to the magnitude of vibration given to the converter by the event that caused AE, that is, the seismic intensity of the earthquake. Amplitude distribution can be obtained by performing statistical processing, and the relative energy levels between the AE events that have occurred can be compared. This may be used to identify different AE generation mechanisms. In addition, the continuous occurrence of high-amplitude events seen in the region off the straight line on the amplitude distribution may correspond to the growth of harmful defects. Thus, the maximum amplitude value is an important measure of the risk of an AE event.

The time until the AE waveform first exceeds the threshold value, passes through the maximum amplitude, and falls below the threshold value is called the signal duration. That is, the signal duration is defined as the time from the first threshold crossing to the last threshold crossing at the time of signal input, that is, the tactile duration of one hit. By integrating this value with the signal rise time and the maximum amplitude value, it is possible to obtain information on the rough waveform of the input signal. Based on this information, it may be possible to identify different AE sources.

In this embodiment, a predetermined DA value is used. Here, the DA value is calculated by the following formula.

DA value = (Signal duration-Rise time) / Maximum amplitude value This value represents the reciprocal of the slope from when the waveform shows the maximum amplitude value to when it falls below the threshold value. That is, this value can be used to evaluate the degree to which the AE waveform is continuously generated.

In this embodiment, it is preferable to use not only the DA value but also the RMS value of the AE waveform.

Here, the RMS value (Root Mean Square Value) (effective value voltage) is used to know a rough change in AE activity. Since the time constant is as large as about 100 to 200 ms, it cannot cope with rapid phenomena such as sudden AE, but it is suitable when continuous signals such as metal deformation and leak detection are generated. The RMS value is calculated by the following formula. In the following equation, Td is a period and x (t) is a function system of the AE waveform.

That is, in this embodiment, the DA value is used as a parameter for measuring the waveform continuity, and the signal strength of the continuous AE is evaluated by using RMS to obtain a signal that does not generate noise or frequently. I make a distinction.

Next, a specific data acquisition method performed in this embodiment will be described. Four types of rectangular parallelepiped structures having different weights and contact surface materials were moved onto a grinded S50C flat plate, and AE was measured.

FIG. 3 shows an outline of the measurement method as a steel material measurement item. The moving body 21 is installed at a position 100 mm from the center of the right end of the steel material 20, and is moved within a distance of 400 mm as the moving range 22. The movement time was fixed at 8 seconds, and the movement speed was kept constant. The AE sensor acquires elastic waves due to friction and wear that occur during movement as signals. The AE sensor was installed on the back surface of the steel material 20 so as to sandwich the movement start point of the moving body 21 (indicated by circular dotted lines 23 and 23b in the figure).

As for the measurement data, elastic waves when four types of moving objects move over a distance of 400 mm are used. In addition, one moving body was moved a total of 6 times, and data was acquired with a waveform exceeding 40 dB as one hit. The data used for the result is only the waveform generated when the moving body starts to move, in addition to the data in which the waveform having the AE energy of 0 and the AE count value of 1 is deleted as noise. In this measurement, the data generated at the start of movement is the data measured within 0.5 s from the data generated at that moment after confirming the maximum value of the frictional force measured by the force gauge. Parameter analysis was performed using those AEs as the AEs at the time of friction breakage.

The calculation process of the coefficient of friction is shown below. The moving body 21 is moved by the force gauge fixed to the trolley. The time history of the frictional force generated at that time is measured. The coefficient of friction was calculated from the maximum frictional force (static frictional force). The coefficient of friction was calculated using F / P (the value obtained by dividing the frictional force F by the vertical load P), which is Coulomb Amonton's law. The vertical load was obtained from the mass of each moving body 21. The result of the coefficient of friction is shown in FIG.

Next, the measurement result will be described. The DA value and RMS value of AE of each moving body 21 are shown by friction coefficient. The coefficient of friction is shown in FIG. The plot is changed according to the coefficient of friction. □ indicates the case where the friction coefficient is 0.17, △ indicates the case where the friction coefficient is 0.27, × indicates the case where the friction coefficient is 0.2, and ◇ indicates the case where the friction coefficient is 0.27. show.

Compared to the AE generated in a moving body with a friction coefficient of 0.2 or less, the AE generated in a moving body with a friction coefficient of 0.27 shows a DA value of 2000 or more and a high RMS value of 0.003 or more. , It can be confirmed that the waveform of a strong signal is continuously measured. Compared to the case where the coefficient of friction is high, the one with a high coefficient of friction causes more friction, deformation and breakage due to wear, and AE occurs more frequently with it. As a result, a dense continuous waveform was obtained, and AE with a high DA value and RMS value was measured.

From these results, a relationship was found between the friction coefficient and the DA value-RMS value, and it is considered effective to apply the DA value-RMS value to the friction coefficient estimation.

As a guideline for evaluating the degree of deterioration of the gate pin, the design value of the friction coefficient is set to 0.2. Using the design value as a guide, the coordinates of the RMS value (V) and the DA value (ms / V) were classified as shown in FIG. 6 based on the result of FIG. The region of AE confirmed only with a friction coefficient of 0.27 was set as the dangerous side. When the measured AE is plotted in a range showing a DA value of 2000 or more and an RMS value of 0.003, it can be inferred that the measured AE occurred on the contact surface close to the friction coefficient of 0.27.

On the other hand, in the AE generated on the contact surface having a friction coefficient of 0.2, the RMS value shows a value of 0.003 or more, but the AE that is not in the dangerous region can be confirmed. It shows a strong signal equivalent to that of an AE that enters the danger zone, but is an AE that does not occur continuously. Since it is not a continuous waveform, it is considered that friction and wear are not strongly generated.

In order to show a continuous waveform with a DA value of 2000 or more, a waveform having a signal strength of RMS value of 0.003 or more needs to appear frequently, and it is considered unlikely that the waveform will enter the dangerous region. On the other hand, a waveform having a DA value of 2000 or more in a dangerous region but not having an RMS value is a continuous waveform because the DA value is high. Since the RMS value is low, friction and wear do not occur strongly, but there is a possibility that the signal will change to a stronger signal by changing to a denser waveform in the future.

The change to a dense waveform may change densely when several similar waveforms appear in a few μ, and it is data that can enter the dangerous area. Therefore, the area where the DA value enters the dangerous area and the area where the RMS value does not enter is designated as the caution area as the AE area where it is necessary to continue the inspection with caution in the future. The case where both the DA value and the RMS value are outside the dangerous area is evaluated as safe. From the above, the identification index as shown in FIG. 7 can be created.

FIG. 8 shows a flowchart of the operation of the control unit (CPU) 11 of the gate pin inspection device 10 as described above. As shown in FIG. 8, the control unit 11 acquires AE data (S11), calculates a DA value (S12), calculates an RMS value (S13), associates it with a friction coefficient (S14), and results. It is evaluated (S15) to determine whether it is a safe area, a caution area, or a dangerous area (S16 to S18).

Next, as a different embodiment, data were obtained for the case of a corroded flat plate. The identification index created from the results of the grinded plate was applied to the corroded plate. The relationship between the DA value and RMS value of AE generated on the contact surface between the corroded flat plate and each moving body is shown by the friction coefficient, and it is divided into a safety area, a caution area, and a danger area with a DA value of 2000 and an RMS value of 0.003 as boundaries. .. The AEs plotted in the dangerous area have a friction coefficient close to 0.27. The AEs plotted in the dangerous area are plotted in the dangerous area, and the result is that the discrimination index is satisfied. The results are shown in FIG.

Next, since the on-site measurement was performed, the results will be explained. In order to evaluate the soundness of the radial gate in service, on-site measurement was performed using the AE method. The identification index was applied to the AE measured at that time.

As in the laboratory experiment, it is limited to AE with no friction. According to the gate displacement data, the displacement of the gate was confirmed around 26s from the start of wire winding. However, it may be displaced due to the deflection of the pedestal, and it is difficult to identify the inside of the bearing. Therefore, the AE measured between 25 and 28 s with a margin is regarded as the friction cutoff. In addition, the waveform with AE energy of 0 and AE count number of 1 was deleted as noise. In addition, ch. 1, 2, ch. Among the signals detected in 3 or 4 pairs, an EDT (event definition time) was set and an AE event was selected. The EDT was calculated by dividing the distance between the sensors (400 mm) by the elastic wave velocity (5,500 m / s) transmitted through the steel plate.

The result will be described. FIG. 10 shows the result of applying the identification index to the relationship between the DA value and the RMS value of AE in the gate pin.

No AE showing a high value that entered the dangerous region was confirmed in both the DA value and the RMS value. The calculated friction coefficient shows a very small value, and it is considered that the environment was not such that AE with high amplitude was continuously generated. Even in the field measurement, it was possible to identify to some extent by the identification index created by the laboratory experiment.

When the evaluation is performed using the index, it is preferable to judge that it is dangerous when the AE in which one of the measurement results falls into the dangerous area is measured out of the three measurements. The reason is that the coefficient of friction was performed 6 times for each moving body in the laboratory experiment, but there was a result that AE entering the dangerous area could not be confirmed in the moving body having a high friction coefficient. Therefore, it is necessary to perform the test multiple times.

Even in the field measurement, it was possible to identify to some extent by the identification index created by the laboratory experiment. In the future, we will propose an identification index that can estimate the friction coefficient in more detail by making the classification finer.

In the above embodiment, the case where the frictional force of the gate pin is detected has been described, but the present invention is not limited to this. It can also be used for such purposes.

Although embodiments of the present invention have been described with reference to the drawings, the invention is not limited to the illustrated embodiments. It is possible to make various modifications to the illustrated embodiments within the same scope as the present invention or within the equivalent scope.

According to the present invention, since it is possible to provide a gate pin inspection device capable of inspecting a gate pin inexpensively and easily, it is advantageously used as a gate pin inspection device.

10 Gate pin inspection device, 11 Control unit (CPU), 12 Waveform acquisition unit, 13 Evaluation unit, 14 Output unit, 15 AE sensor.

Claims (4)

The AE sensor attached to the gate pin as a bearing member of the radial gate,
Evaluation for evaluating the frictional force of a gate pin as a bearing member of a radial gate using a waveform acquisition unit that acquires an AE waveform from the AE sensor and a predetermined DA value obtained based on the waveform acquired by the waveform acquisition unit. A unit and an output unit that outputs the evaluation result of the evaluation unit are included.
The DA value is a gate pin inspection device as a bearing member of a radial gate , which is represented by the reciprocal of the slope from when the AE waveform shows the maximum amplitude value to when it falls below a predetermined threshold value. The gate pin inspection as a bearing member of the radial gate according to claim 1, wherein the evaluation unit evaluates the frictional force of the gate pin as the bearing member of the radial gate using the RMS value of the waveform acquired by the waveform acquisition unit. Device. The second aspect of claim 2, wherein the evaluation unit identifies the frictional force of the gate pin as a bearing member of the radial gate into a plurality of regions by using the AE waveform acquired by the waveform acquisition unit and the RMS value of the AE waveform. Gate pin inspection device as a bearing member for radial gates. This is a gate pin inspection method for a radial gate bearing member that inspects the frictional force of the gate pin as a radial gate bearing member using an AE sensor.
A step of acquiring an AE waveform from an AE sensor attached to a gate pin as a bearing member of a radial gate, a step of evaluating the frictional force of the gate pin using a predetermined DA value based on the acquired waveform, and an evaluation result are output. A gate pin inspection method as a bearing member of a radial gate , wherein the DA value includes an output step and is represented by the inverse of the slope from when the AE waveform shows the maximum amplitude value to when it falls below a predetermined threshold value.

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