JPH04301727A - Measuring method for resonance oscillation frequency and its measuring equipment - Google Patents

Abstract

PURPOSE:To accurately measure resonance oscillation frequency at all times regardless of the skill of an operator. CONSTITUTION:An oscillation detector is installed onto a part of a measured oscillating body, and the amplitude of the oscillating body is detected based on detected output. When the oscillating body is in a stationary state, the amplitude in stationary state can be indicated accurately and stably in a digital form by means of comparatively low speed sampling. When resonance oscillation frequency is to be measured, the stable amplitude in comparatively low speed sampling can be held with a hold button 28 depressed, following which, if a trigger button 31 is depressed before a drive source is suspended, switch-over to high speed sampling can thereby be made. After that, the driving force of the oscillating body becomes zero, oscillation is therefore gradually damped while being freely oscillated. When the amplitude is damped to a specified one, damping is detected by a microcomputer with the oscillation frequency of free oscillation counted while being started at this time for the specified period T of time, so that resonance oscillation frequency can thereby be indicated on an indication section in a digital form.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring resonance vibration frequencies.

0002

[Prior art and its problems] Vibrating machines, such as vibrating parts feeders and vibrating feeders, are widely used in industry, but the amplitude and frequency of these vibrators are regularly measured. I try to check whether the vibrator is operating normally, but in some cases I may want to measure the resonant vibration frequency of this vibrator.

Conventionally, in such cases, measurements have been made using a so-called vibration frequency meter, which consists of a large number of parallel leads, and these are cantilever beams that measure the resonance vibration frequency. They are arranged in order from the lowest to the highest (this is called the Frahm type). Apply the casing containing these to a part of the vibrator to be measured, and visually observe which of the leads on this frequency meter swings the most immediately after the vibrator starts operating or immediately after the operation stops, and determines which of the leads swings the most. The resonant vibration frequency of the vibrator is detected from the display frequency corresponding to the reed. However, it is not just one of the many reeds installed side by side that is swinging a lot, but the leads before and after it are also swinging a little. From now on, we will detect the resonant vibration frequency in an analog manner.

[0004] Since the measurement method described above is used, there are individual differences, and the accuracy of reading the maximum swinging lead and the accuracy of reading from a plurality of leads also vary depending on environmental conditions.

[0005] In view of the above-mentioned problems, the present applicant first aimed to provide a portable resonant vibration frequency meter that can easily and accurately measure the resonant vibration frequency of each vibrator without individual differences. The main body is provided with a display section that receives the output of the display device and digitally displays the vibration frequency on the front panel portion of the casing that incorporates at least a microcomputer, a battery, and a display device connected to the output terminal of the microcomputer. It consists of a vibration detector that can be attached and detached to a part of the vibrating body to be measured, and a conductive cord that derives the detection force of the vibration detector and is connected to the connector part of the main body. The resonant vibration frequency of the vibrating body to be measured is displayed as a digital value as a calculation result of the microcomputer from the detected force of the vibration detector attached to the part of the vibrating body immediately after the vibrating body to be measured is started or stopped. We proposed a portable resonant vibration frequency meter characterized by a display on the front panel (Utility Application No. 2-60050).

However, in the above-mentioned instrument, in order to measure the resonant vibration frequency, the vibration frequency of the vibrating object to be measured in a steady state is sampled and measured at a predetermined sampling frequency, and this is displayed as a digital value on the display section. ing. In addition, this allows the steady state frequency of the vibrating body to be measured to be displayed stably, but when measuring the resonant vibration frequency, continuous mode (CONT.
) and single mode (SINGLE) to the single mode side, immediately stop driving the vibrating body to be measured, and immediately press the trigger button. The free vibration frequency is calculated by a microcomputer and displayed, but depending on the type of vibrating body to be measured, the amplitude attenuation rate immediately after operation is very large, and when the trigger button is pressed, In some cases, the amplitude of free vibration has already become almost zero, and in this case, it is impossible to accurately measure the resonant vibration frequency, or it becomes impossible to measure the resonant vibration frequency. Therefore, unless the trigger button is pressed quickly and at the right time immediately after the operation is stopped (specifically, immediately after the power switch is turned off), the resonant vibration frequency cannot be accurately measured. The timing to press this trigger button is very difficult.

[0007]

[Problems to be Solved by the Invention] The present invention has been made in view of the above problems, and does not require any skill on the part of the operator.
An object of the present invention is to provide a resonant vibration frequency measuring method and a measuring device that can accurately measure the resonant vibration frequency of any vibrator.

[0008]

[Means for Solving the Problems] The above object is to attach a vibration detector to a part of the vibrating body to be measured, and to set the output of the vibration detector during the driving of the vibrating body to be measured to a first predetermined value. measuring at a sampling period, holding the measured value, then measuring the output at a second predetermined sampling period shorter than the first predetermined sampling period, and stopping the driving of the vibrating body to be measured. detecting that the amplitude of the output has decreased by a predetermined percentage from the held measurement value; and detecting that the amplitude of the output has decreased by a predetermined percentage from the held measurement value, and the output during a predetermined time at the second predetermined sampling period from the time of detection. This is achieved by a resonant vibration frequency measuring method characterized in that the vibration frequency of the resonance vibration frequency is measured.

[0009] Alternatively, at least a microcomputer, a battery, and a display device connected to the output terminal of the microcomputer are built in, and a display section is provided on the front panel portion to digitally display the vibration frequency in response to the output of the display device. It consists of a main body, a vibration detector that can be attached and detached to a part of the vibrating body to be measured, and a conductive cord that derives the detection force of the vibration detector and is connected to the connector part of the main body. The resonant vibration frequency of the vibrating body to be measured is displayed as a digital value as a calculation result of the microcomputer from the detected force of the vibration detector attached to a part of the body immediately after the operation of the vibrating body to be measured is stopped. A resonant vibration frequency meter is provided with a hold means and a trigger means, and by operating the hold means, the vibration frequency and amplitude of the vibrating body to be measured during operation are displayed at a first predetermined sampling period. measure and hold it, and then measure the vibration frequency and amplitude at a second predetermined sampling period shorter than the first predetermined sampling period by operating the trigger means, and drive the vibrating body to be measured. When the amplitude of the vibrating body decreases to a predetermined percentage from the held amplitude value after stopping, the vibration frequency is measured at the second predetermined sampling period, and this measurement result is displayed on the display section. This is achieved by a resonant oscillating frequency instrument, which is characterized by being made to display.

0010

[Operation] The driving frequency of the vibrating body to be measured in a steady state is measured at a relatively slow sampling rate. Therefore, it is possible to stably and accurately measure the amplitude of the vibrating object to be measured, and to accurately recognize the amplitude in a steady state. When measuring the resonant vibration frequency of the vibrating body to be measured, the sampling state is set at a second predetermined sampling period, that is, high-speed sampling, and then the drive source of the vibrating body to be measured is stopped. The amplitude of the measurement vibrating body is attenuated by free vibration. Therefore, when it is detected that this amplitude has attenuated to a predetermined rate by comparing it with the amplitude value measured during slow sampling in a steady state, based on this detection, the attenuation waveform is measured for a predetermined time from the time of this detection, and the microcomputer The vibration frequency is calculated by high-frequency sampling, and this is displayed as a digital value on the digital display section. Conventionally, after stopping the driving of the drive source of the vibrating body to be measured, by operating a means corresponding to a trigger button, the trigger means is operated at a good timing after a short period of time after the drive has stopped, and the vibrating body to be measured at this point is The timing of this operation was very difficult when measuring the free vibration frequency of Since the damping state in free vibration is being measured, it is possible to detect when this state has reached a certain value and accurately measure the resonant oscillation frequency of the vibrating body to be measured.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Portable vibration display devices according to embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show front views of the portable vibration display according to the present embodiment. As shown in FIG. 4, it has a built-in liquid crystal display device 14 and a battery 17, and the battery 17 is stably supported via a mounting part 18, as well as a microcomputer (not shown). The above-mentioned liquid crystal display device 14 and the like are held in a predetermined position within the casing 11 by mounting screws 15 on the chassis 13 via spacers 16. A power switch 19 is provided on the left side of the front panel section 12, but this is a well-known double push switch, and when pressed once, the battery 17 supplies power to each section, and when pressed again, the power is turned off. It is designed to be blocked. To the right of this is a lamp 20 that lights up when the power switch 19 is turned on.
is provided, and when this is on, it indicates that power from the built-in battery 17 is being supplied to each part. Further, a display section 21 is provided below these, and in the embodiment, this consists of an amplitude display section 22a and a vibration frequency display section 22b arranged in the horizontal direction, and these are the liquid crystal section of the above-mentioned liquid crystal display device 14. As will be described later, the detected force from the vibration detector is calculated by a microcomputer, and the resulting digital value is driven by the driver output from the microcomputer to drive the liquid crystal display device 14 to display the display section 22a, 22
At b, the amplitude and vibration frequency are displayed as digital values, for example, as shown in the figure. At the top of the vibration width display section 22a, a symbol (mm) representing the width of vibration is engraved off the liquid crystal section, and on the vibration frequency display section 22b, the frequency is displayed as a digital value. According to this embodiment, in the liquid crystal section above this, the unit is displayed in VPM or Hz, so these are selectively displayed.

[0013] Also, below the display section 21 is a hold button 2.
8 and a trigger button 31 are provided, and when this hold button 28 is pressed, the amplitude value and frequency during continuous operation are held and displayed on the display section 21. Normally, the frequency and amplitude during continuous operation are displayed moment by moment at a low-speed sampling period. Further, if the trigger button 31 is pressed after pressing the hold button 28, it is possible to switch to high frequency sampling. When the operation is stopped, the driving force to the vibrator is cut off, but the vibration until it stops is a resonant free vibration, so this frequency is detected by a vibration detector and calculated by a microcomputer as described later. This frequency is displayed as a digital value on the vibration frequency display section 22b. Therefore, the resonant frequency of the vibrating body to be measured can be detected. A function changeover switch 32 is further provided at the lower part of the front panel section 12. This is a rotary switch, and by rotating the knob 33 of the pointer 34, it can be switched to the A, B, C, or D position to perform each mode. For example, at the illustrated position A, a normal measurement state can be obtained. That is, the amplitude and vibration frequency of the vibrating body to be measured can be displayed on the display section 21. By switching the pointer 34 to position B using the knob 33, the portable vibration display 10 operates as a transmitter for communicating with a personal computer, and the display unit 21 is transmitted to a personal computer placed nearby.
The amplitude and vibration frequency can be transmitted as digital values. In C and D, this is further multifunctional.

As shown in FIG. 4, the casing 11 is further provided with trimmer resistance adjusters 35 and 36, one for adjusting the feeder swing width display and the other for adjusting the conveyor swing width display. This allows the analog input of the A/D converter in the circuit diagram of FIG. 5 to be manually adjusted.

Next, referring to FIG. 5, the electric circuit built into the above-mentioned portable vibration display 10 will be explained. In FIG. 5, the vibration detector 40 has a shape as shown in FIG. 7, and as will be described further later, this detection power is supplied to a low-pass filter 41, where it filters out high-cycle signal components such as noise. is removed and this output is supplied to amplifier 42. The amplified output here is supplied to the A/D converter 43, which converts the analog value into a digital value, and this digital value is supplied to the microcomputer 45. Microcomputer 45
A switch section 46 is further connected to the input terminal side of the switch section 46, which collectively shows the various switches 28, 31, 32, etc. shown in FIG. It is now possible to do so. The microcomputer 45 receives the digital output from the A/D converter 43 and the switch signal from the switch section 46, performs a predetermined calculation, and supplies the result of the calculation to the liquid crystal display section 47. This includes a liquid crystal display device 14 shown in FIG. Furthermore, it is assumed that it also includes a drive circuit for this or a liquid crystal section as a display section 21 as shown in FIG. The output terminal of the microcomputer 45 is further shown as d, which is used for communication with a personal computer at position B, for example, by changing the mode of the operation mode selector switch 28 shown in FIG. This sends a signal to the personal computer 48. Further, the automatic voltage regulator 49 is shown by a dashed line, but if this also becomes an automatic voltage regulator when the function selector switch 32 is switched to the C position, the voltage will be automatically adjusted by the detection force of the vibration detector at this time. The adjustment section of the device can be automatically driven to automatically adjust to a desired amplitude and frequency. When the hold button 28 in FIG. 1 is pressed on the microcomputer 45, a holding circuit is provided to hold the amplitude and frequency values at that time, and when the trigger button 31 is further pressed, the amplitude and frequency are measured by high-speed sampling. That's what I do. Normally, low-speed sampling is performed, and the period is, for example, 0.7 seconds, but in high-speed sampling, it is 0.2 seconds. Although not shown in FIG. 5, it is assumed that various devices are connected to the output side so as to perform the same functions by switching the function changeover switch 32 in FIG. 1.

Next, details of the vibration detector 40 will be explained with reference to FIG. This is an almost cylindrical casing 5
0, and a force detection element 51 made of, for example, zirconium lead is held on a mounting plate 52 inside the force detection element 51. A flange portion of the casing 50 is fixed to the mounting plate 52 by, for example, screws. Further, the force detected by the force detecting element 51 is derived through a conductive wire 53. A vibration display line 55 is engraved on the upper surface of the casing 50. This is engraved so as to be parallel to and in the same direction as the force detection direction F of the force detection element 51 built into the casing 50. Further, it is assumed that a flat magnet is attached to the back surface of the mounting plate 52. Therefore, the entire vibration detector 40 can be easily attached to and detached from the vibrating body using a magnet.

In FIG. 5, the A/D converter 43 is connected to the terminals of a trimmer resistor device 44 consisting of trimmer resistor regulators 35 and 36 shown in FIG.
The analog input in the D converter 43 is manually adjusted. Also, the gain control section 4 of the amplifier 42
2a, a microcomputer 45 receives the digital output of the A/D converter 43, and receives a gain control signal for changing the gain of the amplifier 42 in order to use a certain number of bits effectively.

Portable vibration display device 1 according to an embodiment of the present invention
0 is configured as described above, and its operation will be explained next.

The vibration detector 40 according to this embodiment is shown in FIG. 7, and the operation of attaching it to the vibrator will now be described. In this embodiment, it is assumed that the vibration of a vibration feeder 60 as shown in FIG. 6 is measured. As is well known, the vibratory feeder 60 includes a trough 61 having a U-shaped cross section and a drive section 62 that transmits an excitation force to the trough 61. The drive unit 62 is configured with a stacked leaf spring, an electromagnet, or the like. The entire vibrating feeder 60 is suspended from a part of the building by coil springs 63a and 63b. When a commercial power supply is applied to the coil of the electromagnet of the drive unit 62, it vibrates at 50 Hz, for example, about 2 mm in the direction indicated by the arrow m. When the mounting plate 52 of the vibration detector 40 shown in FIG.
is fixed to the side of the Vibration detector 4 along with trough 61
0 also vibrates, and a vibration display line 55 is engraved on the top surface of the casing 50. When initially installed, it is installed so that it is parallel to the expected vibration direction m, but if this vibration display line 55 is thin enough and precisely matches the vibration direction, it will be approximately the same thickness as the line when it is at rest. However, if it is tilted in any direction, it will remain as an afterimage on the retina of the eye, so it will be visible with a certain width or an inclined width. Therefore, while watching this, adjust the mounting direction while pinching the casing 50 so that the thickness is approximately the same as that of the vibration display line 55 when it is stationary. When the magnet is fixed to the side surface of the trough 61 at a predetermined angle, the force detection direction F of the force detection element 51 made of lead zirconate inside the casing 50 is parallel to and coincident with the force detection direction F, so that the vibration is accurately detected. can be measured. This vibration detection force, ie, voltage, is supplied via a conductor 53 to a low-pass filter 41 shown in FIG.

In FIG. 2, the pointer 34 of the function changeover switch 32 is switched to face A. In the above-mentioned state, an electric circuit as shown in FIG. This low-pass filter 4
1, ripple-like noise is removed as a high frequency component as shown on this output side, and a low frequency component signal S' is supplied to the amplifier 42. Here, the signal is amplified to a predetermined size and supplied to the A/D converter 43. The microcomputer 45 performs calculations suited to the characteristics of the feeder. That is, the vibration feeder 60 has, for example, 50 yen as described above.
Although it vibrates at a rate of approximately 2 mm per Hz, the acceleration of this type of feeder is approximately 15 to 30 g, and this maximum value is used to determine the analog input to the A/D converter to obtain a full-scale digital value. . Therefore, the amplitude can be detected with high accuracy according to this number of bits. In addition, a clock pulse generator is provided in the microcomputer 45 in a well-known manner, and this clock pulse has a predetermined number of pulses and is highly accurate and does not vary over time. Detect the vibration frequency of the output using low-speed sampling.

The output of the microcomputer 45 is displayed on an LCD (Liquid
d Crystal Display) Supplied to the liquid crystal display section 47. That is, the amplitude and vibration frequency of the vibration feeder 60 calculated by the microcomputer 45 are displayed as digital values on the display section 21 as shown in FIG. That is, it can be seen that the vibration width of the vibration feeder 60 currently being measured is 1.25 mm, and the vibration frequency is 50.25 Hz. Conventionally, the swing width nameplate 1 as shown in FIGS. 10 and 11 was used as a trough 6.
The scale line 3 was pasted on the side of the machine so that it coincided with the vibration direction, and the operator read the intersection point using the afterimage of the oscillating width display lines 4a and 4b on the retina of the eye. It varies from person to person and changes depending on surrounding conditions. According to this embodiment, as shown in FIG. 2, since the amplitude and vibration frequency are displayed as digital values, there are no individual errors and it is possible to measure accurately and uniformly.

In a factory, normally a large number of vibrating feeders as shown in FIG. 40, the amplitude and vibration frequency of the vibrating feeder can be immediately detected and read accurately.

The amplifier 42 also includes a gain control section 4.
2a is provided, which receives the output of the A/D converter 43 supplied to the microcomputer 45, and controls the gain of the amplifier 42 according to this output. In other words, although the number of bits of the A/D converter is constant, the accuracy differs greatly between when the detected acceleration is low and when it is high. I am trying to increase the gain. Therefore, measurement can be performed with the same accuracy regardless of whether the analog input of the gain control section 42a, that is, the detection force is large or small.

Further, in this embodiment, the swing width is measured with higher accuracy than the conventional method as follows. That is, as shown in FIG. 8, the output of the vibration detector 40 has a sine waveform S as a whole, but it contains noise, and for some reason large noises P and P' are often added to the output. When calculating the amplitude by performing double integration for the output S, the amplitude is measured from the highest and lowest values by double integration, so a large noise P as shown in Fig. 8 is generated. , P' occurs, the measured amplitude will be larger than the actual amplitude. If it is an ideal sinusoidal waveform without such noise, there will be no problems and accurate measurements can be made, but as shown in Figure 8, it often contains noise of various sizes. According to the method according to this embodiment, this influence can be eliminated. That is, if the amplitude to be measured is At, the displacement X at each time is X=At sin ωt
/2, differentiate this twice and get [2nd degree differential value of X] = -At
ω2 sin ωt/2.

In this embodiment, this acceleration root mean square R. M.
S. (Root Mean Square), that is, calculate the effective value. That is, the acceleration at each moment is integrated over time, divided by the time in between, and the average value is taken. Therefore, [X2 degree differential value] r. m. s. =
Atω2/(2√2). If this is expressed in grams, Gr. m. s. =Atω2/(2√2g)(g=
9800). Therefore, from now on, the swing width At = 2√2G
r. m. s. g/ω2.

The amplitude At is calculated by measuring this [2nd degree differential value of X] at each instant and taking the temporal average value. Therefore, by taking the average value over a certain period of time, even if large noises P and P' occur in a short period of time as shown in FIG. 8, the influence of this can be almost ignored.

Next, the case of measuring the vibration of a vibrating conveyor will be explained. Generally, a long trough and a base block arranged parallel to the base block are connected by a leaf spring inclined in a predetermined direction, and the trough is vibrated in a direction almost perpendicular to the longitudinal direction of the leaf spring by a crank drive. For example, if the frequency is 552r. p. m. and much lower than vibratory feeders. However, the swing width is 12.
Although it is large at 8 mm, the acceleration is proportional to the square of the frequency and proportional to the amplitude, so the acceleration is much smaller than that of the vibratory feeder. Generally, the acceleration of a vibrating conveyor is 1
It is about 5g to 5g. Therefore, the output detected by the force detection element 51 in the vibration detector 40, that is, the voltage per 1 g, is low. However, according to this embodiment, even in such a case, the output of the A/D converter can be measured with high precision similar to that of a vibration feeder by controlling the gain of the amplifier. Although not shown, a vibration detector 40 is fixed to the side surface of the trough of the conveyor in the same manner as in the case of the vibration feeder. As a result, as shown in Fig. 1, the amplitude is 12.8 mm and the frequency is 552.0 r. p. m. is displayed as a digital value. Note that the swing width is in the same unit, so m
m, but in the case of a conveyor, it is in VPM units, so the display unit 22b displays the range from Hz to r.m. p. m. The display can be switched to .

Next, a method for measuring the resonance vibration frequency of a vibrator, for example, the vibrating feeder 60 will be explained. In this case, the hold button 28 shown in FIG. 1 is first pressed, and the current swing width is held in the microcomputer 45. Next, when the trigger button 31 is pressed, the microcomputer 45 switches to high-speed sampling. In this state, power supply to the drive unit 62 of the vibrating feeder 60 is cut off. When the amplitude held by the microcomputer 45 decreases to a predetermined percentage, 80% in this embodiment, the frequency of vibration during a predetermined period of time is measured from this point on. Therefore, the resonance vibration frequency of this vibration feeder 60 is 52.5H.
z and is digitally displayed on the vibration frequency display section 22b.

When the power supply to the drive unit 62 of the vibration feeder 60 is cut off, as shown in FIG. 9, the displacement of the trough 61 does not immediately become zero from the vibration as shown in FIG. 8, but becomes zero after undergoing a transient phenomenon. The amplitude of this decreases exponentially, but since the driving force has already been cut off, it is attenuated by free vibration. This free vibration is a resonant frequency, as is clear from vibration engineering. Therefore, if the switch is turned off and the power is cut off at time t1, the amplitude will decrease exponentially from this point on. Assuming that the bird amplitude has decreased to 80% at time t2, the microcomputer 45 calculates the number of waves during the time T2, compares it with the clock pulse built in the microcomputer, reads this number, and The number of waves per unit time, that is, the resonance frequency (same meaning as resonance vibration frequency, hereinafter the same) is calculated. This is 52.5 Hz in the vibration frequency display section 22b shown in FIG. For example, in this type of resonance type vibrator, the weight of the trough and the spring constant of the leaf spring are set so that the resonance frequency is close to the driving frequency in order to obtain a large amplitude with a small driving force. However, if the resonance frequency detected by this method changes significantly, for example, if the driving frequency is 50 Hz, 70
When a resonant frequency such as Hz or 30 Hz is read, it is considered that a trouble has occurred in some part of the vibratory feeder 60. For example, it is possible that the leaf spring is damaged, or some kind of weight adjustment block slips down, etc., so the malfunctioning part can be repaired immediately during maintenance. In the measurement of this resonant vibration frequency, the vibration detectors 40 shown in FIG.
By installing it, it is possible to immediately and reliably detect it, which makes maintenance much easier than before.

Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited thereto, and various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiment, the vibration detector 40 is configured such that the detection direction of the acceleration detecting element made of lead zirconate is parallel to the surface of the mounting member. Although it was designed to be easily installed parallel to the vibration direction, instead of such a vibration detector, a vertical type vibration detector, which has been widely used in the past, is used. On the other hand, since it is located in the vertical direction, a special member was required to mount it when detecting the amplitude of the vibrator, but in the present invention, since the resonant vibration frequency is detected, it can be mounted precisely in line with the vibration direction. Therefore, conventional vibration detectors are also fully applicable. Alternatively, all other conventionally known vibration detectors are applicable.

Furthermore, in the above embodiment, the portable vibration display device 10
There is no particular limitation on the size of the device, and although it has only been described as being portable, it may also be of a handheld unit type, that is, a size that allows a worker to operate various buttons with one hand. This further facilitates maintenance of each vibrator.

Furthermore, although a liquid crystal display was used as the display section in the above embodiments, a known display device may also be used. For example, a display device in which a plurality of bar-shaped neon tubes are arranged in a figure "8" may be used. Numbers are displayed by selectively driving these neon bars in a known manner. Alternatively, a large number of pixel-shaped light emitting elements may be arranged and selectively driven. Furthermore, in the above embodiment, the vibration detector 40
Although the magnet of the attachment part was used to attach the oscillator to a part of the vibrator to be measured, a suction plate using a vacuum effect may be used instead. This becomes effective when a part of the vibrator is made of non-magnetic material.

In the above embodiment, the switch 32 is provided on the panel section 12, but this may be omitted to further simplify the structure and provide only a display section for displaying the resonant vibration frequency.

In the above embodiment, the sampling period of high-speed sampling was set to 0.2 seconds, but this time may be changed depending on the driving frequency of the vibrator to be measured or the expected resonant vibration frequency. good. In addition, the rate of attenuation from a steady state to a predetermined amplitude in a damped state can be changed and adjusted, and the frequency of free vibration in a predetermined time from the point of detection can also be adjusted according to the damping speed (the elasticity supporting the movable part). (It changes depending on the viscosity coefficient of the means, for example, a leaf spring or a rubber spring.) The predetermined time may be changed.

[0036]

Effects of the Invention As described above, according to the resonant vibration frequency measuring method and measuring device of the present invention, the resonant vibration frequency can be easily detected, and the detected value is displayed as a digital value on the display. Since the display is displayed on the display, measurements can be made accurately and immediately regardless of individual differences or regardless of ambient conditions, making maintenance faster and easier than before, especially in factories where many vibrators are installed side by side. can do.

[Brief explanation of drawings]

FIG. 1 is a front view of a portable vibration display according to an embodiment of the present invention.

FIG. 2 is a similar front view for explaining the operation of the portable vibration display device.

FIG. 3 is a similar front view for explaining the operation of the portable vibration display device.

FIG. 4 is a side view of the portable vibration display device.

FIG. 5 is a block diagram of an electric circuit built into the display.

FIG. 6 is a side view of a vibration feeder as an example of a vibrator that is measured by the portable vibration display of this embodiment.

FIG. 7 is a perspective view of a vibration detector in the portable vibration display.

8 is a detection force waveform of a vibration detector attached to the vibration of the vibrator to be measured shown in FIG. 6; FIG.

FIG. 9 is a waveform diagram showing a transient phenomenon of the output of the detector when the power to the drive section of the vibrator is cut off.

FIG. 10 is a front view of a conventional swing width nameplate for reading the swing width.

FIG. 11 is a side view for explaining the same effect.

[Explanation of symbols]

10 Portable vibration indicator 14 Liquid crystal display device 21 Display section 22b Vibration frequency display section 40 Vibration detector 45 Microcomputer

Claims (5)

[Claims] 1. A vibration detector is attached to a part of a vibrating body to be measured, an output of the vibration detector is measured at a first predetermined sampling period while the vibrating body to be measured is being driven, and the measurement comprises: holding the value, then measuring the output at a second predetermined sampling period shorter than the first predetermined sampling period, stopping the driving of the vibrating object to be measured, and the amplitude of the output is detecting that the held measured value has decreased to a predetermined percentage; and measuring the vibration frequency of the output during a predetermined time from the point of detection at the second predetermined sampling period. A method for measuring a resonant vibration frequency, characterized in that: 2. At least a microcomputer, a battery, and a display device connected to an output terminal of the microcomputer are built in, and a front panel section is provided with a display section that receives the output of the display device and digitally displays the vibration frequency. It consists of a main body, a vibration detector that can be attached and detached to a part of the vibrating body to be measured, and a conductive cord that derives the detection force of the vibration detector and is connected to the connector part of the main body. The resonant vibration frequency of the vibrating body to be measured is displayed as a digital value as a calculation result of the microcomputer from the detected force of the vibration detector attached to a part of the body immediately after the operation of the vibrating body to be measured is stopped. A resonant vibration frequency meter is provided with a hold means and a trigger means, and by operating the hold means, the vibration frequency and amplitude of the vibrating body to be measured during operation are displayed at a first predetermined sampling period. measure and hold it, and then operate the trigger means to trigger the first
The vibration frequency and amplitude are measured at a second predetermined sampling period shorter than the predetermined sampling period of A resonant vibration frequency meter, characterized in that when the vibration frequency has decreased to a predetermined rate, the vibration frequency is measured at the second predetermined sampling period, and the measurement result is displayed on the display section. 3. The main body further includes an amplifier that receives the output of the vibration detector and an analog/digital converter that receives the output of the amplifier, and supplies the output of the converter to the microcomputer. 3. The resonant vibration frequency according to claim 2, wherein the microcomputer supplies the amplifier with a control signal that adjusts the gain of the amplifier according to the frequency of the output of the analog/digital converter. Instrument. 4. When the frequency of the output is greater than the predetermined frequency, a first control signal for adjusting the gain to a relatively small value; and when the frequency of the output is less than the predetermined frequency. In some cases, a second control signal for adjusting the gain to a relatively large value is supplied to the amplifier, and the first control signal includes a digital display of the vibration frequency in Hz (times per second). , in the second control signal VPM
3. The measuring device according to claim 2, wherein the measuring device is digitally displayed in (times/minute). 5. The vibration detector includes an acceleration detection element and a mounting means for supporting the acceleration detection element, and the mounting means is detachably attached to a part of the vibrating body to be measured, and the vibration detector is always connected to the acceleration detection element. The measuring instrument according to any one of claims 1 to 3, wherein the measuring instrument is attachable to the part in parallel to the acceleration detection direction of the element.