JPH02163629A - Dynamic balance tester - Google Patents

Abstract

PURPOSE:To improve the S/N in the dynamic balancing machine by providing a speed proportion type vibration detector, a means for bringing an output signal of this detector to triple integration as to time, and a means for calculating a dynamic unbalance from inter-bearing/balance correction surface distances, etc., which are preset and a triple integral value. CONSTITUTION:Vibration working on bearings 2L, 2R due to centrifugal force generated in a specimen is detected by moving coil type pickups 4L, 4R being speed proportion type vibration detectors, and its output signal is amplified by a preamplifier 5. Subsequently, its output signal is brought to triple integra tion as to time by an integrator 6a and a double integrator 6b. Also, inter- bearing/balance correction surface distances (a), (b), an inter-bearing distance (c) and correction radiuses rL, rR are preset to a memory 13 through a keyboard 15. A CPU 12 calculates a dynamic unbalance quantum to be corrected, namely, an unbalance mass and an unbalance angle from these data and two pairs of X components and Y components which are led in through a synchronous rectifier 10 and an A/D converter 11, and stores its result in a memory, and also, displays 14 it.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application This invention relates to a hard type dynamic balance testing machine having a highly rigid bearing structure.

B. Prior Art In conventional hard-type dynamic balance testing machines, a piezoelectric element type pickup (such as a load cell) was used as an unbalance detector (pick amplifier).

C1 Problems to be Solved by the Invention However, piezoelectric element type pickups have a sensitivity of 100 to 1. ooop C70 (p C is picocoulomb, G is weight acceleration) is extremely low, and the output impedance is very high (on the order of MΩ), so its output signal is very weak (on the order of μ■).

In addition, piezoelectric pickups have a characteristic of having a very wide frequency response range, but the frequency range required for hard-type dynamic balance testers is limited to the low frequency range. Since this method also detects high-frequency signal components that are not necessary for the test, the level of noise, which is noise vibration transmitted from the bearings and the foundation of the testing machine, is high.

Due to the above synergy, in a conventional dynamic balance tester that uses a piezoelectric element type pickup as an unbalance detector,
This invention aims to improve the S/N ratio in a hard type dynamic balance tester, which has a problem of a poor S/N ratio.

01 Means for Solving the Problems In order to achieve the above object, the present invention has the following configuration.

That is, the present invention provides a speed proportional vibration detector as an unbalance detector for detecting the unbalance of a rotating test body in a hard type dynamic balance testing machine having a highly rigid wheel bearing structure, and Means for triple-integrating the output signal of the speed-proportional vibration detector with respect to time, and calculating dynamic unbalance from the preset distance between the bearings and balance correction surfaces, the distance between the bearings, the correction radius, and the value of the triple integral. The invention is characterized in that it includes a means for doing so.

E1 Effect The effect of the configuration of this invention will be explained with a comparison with a conventional example.

An arithmetic expression for corrected surface separation is determined based on FIG.

In FIG. 3, 1 is a test specimen, 2. ．． 2R is left and right bearings that rotatably support the shaft portion of the test specimen 1, and 3L and 3m are highly rigid springs that support the bearings 2L and 2R.

If an unbalanced mass exists in the test body 1, a centrifugal force is generated on the test body 1 as the test body 1 rotates, and the force caused by this centrifugal force acts on the bearings 2+-, 2R, and the spring 31.3 −
The bearing, 2R, vibrates against the

Conventionally, bearings 2. ．． Whereas the force acting on the bearing 2R was detected by a piezoelectric element pickup which is a force detection type unbalance detector, in this invention, the force acting on the bearing 21 is detected due to centrifugal force.
．． ．． The vibration occurring at 2M is detected by a velocity proportional vibration detector (for example, a moving coil type pickup: not shown).

Left and right balance correction planes I on the specimen 1.

In R, the modified radius, 1 +, , , +, respectively
Assume that an unbalanced mass m l, + m * exists at the position II. Each spring 31. ．． 3. The spring constants of , , and , respectively, are determined in the axial direction from the center of the left bearing 2L to the left balance correction surface R along the direction of the rotation axis of the test specimen 1. The distances are respectively a and b, and the distance between the centers of the left and right bearings 2L and 2 degrees (distance between bearings) is C.

When the test specimen 1 is rotated at an angular velocity ω, the centrifugal force acting on the left and right balance correction surfaces [7, R, respectively, is expressed as p
t, the forces acting on the positions of bearings 2 on the left and right sides of FR1 are T! 4. Let it be ν8.

Left and right balance correction surface, centrifugal force acting on R, iF
++ is F L”' m L? + ω2...
・・・・・・・・・・・・・■F H'= m u i
” trω2 ・・・・・・・・・・・・・・・
・・・・■Also, the amplitude displacement of the left and right bearings 2t and 2R is 7
If Lma is □, the shaft 4 that the left and right bearings 2L and 2R receive
．． ν, is ra-=kLmac=to ma7.・・・・・・・・・・・・
・・・・・・・・・■pm-ni＊feather'8-nima,
・・・・・・・・・・・・・・・・・・■However, here, k+,=kR=Nitoshi.

Left and right dynamic imbalance υ1. υ, is, Ut = m, γ” ・・・・・・・・・
・・・・・・・・・■UR=mH7g・
・・・・・・・・・・・・・・・・・・■0.0 type, ■,
■From the formula, vL−ω2 ・・・・・・・・・・・・
...... ■FR-U, ω2 ...
・・・・・・・・・・・・・・・■ From the condition of balance of static forces, YL + p t + 'p''* 1F R-Q ・・
・・・・・・・・・・・・・・・・・・ ■From the condition of moment balance around the left side modified surface, FL a −FTl (b-a) +'FR(C-a
) = 0・・・・・・・・・・・・・・・・・・ [Phase] Also, from the condition of moment balance around the correction plane R on the right side, FLb+p, (c-b) -FL- (ba-a)=0...
・・・・・・■ ■■1■, ■, ■ Substituting the expressions into the [phase] expression, akma,
(b a) TJiω” + (c-a)kma.-O・・・・・・・・・・・・・
...@■,■,■,■When substituting the expressions into the 0 expression, bk
Ma, -1-(c-b)k ma, -(b-a)υ, ω2-0 ・・・・・・・・・・・・
[Phase] ■, If we find Ma, -, Ma from the o formula, we get (c-
a)+b ([ b) 111R c ・・・・・・・・・・・・・・・・・・0c ・・・・・・・・・・・・・・・・・・■ Moving coil type big amplifier , is a speed-proportional vibration detector, and the voltage ff, i! , occurs. That is, V1. QC71ω・・・・・・・・・
・・・・・・・・・・・・■PoROCma×ω
・・・・・・・・・・・・・・・■Here, if the constants A, B, and C5D are c c c c , then the voltage po1. Bi, is, ■, @formula, ■, ■From 2, giL = (AUl, +BU11) ω” ・,
, , , , , −, −, , , @f* −(cQt, +D
UR) ω3 ・・・・・・・・・・・・・・・■

In other words, the voltage generated by the speed proportional vibration detector E! ,,P
', is proportional to the simultaneous number of orders of the dynamic unbalance U'L+υ8, and is proportional to the cube of the angular velocity ω.

Here, if voltage color 1 po 2 is expressed by a sin function, EL = E +, 6 sin (6J t-φ,) ER =
E), (, sin (ω is one φ7) these E,,,ER
By triple integrating with respect to time, we get LO 5SSELdi” = cos (ωL
−φL )ω3 RQ SSSERdt3= cos (ωt−φ,
)ω3, and its magnitude becomes the original j/ω3.

Therefore, ω3 is eliminated from the 0-fold ■ equation, and 5SSEt
dt3=AUL→-BU, ・・・・・・・・・・・・
・・・・・・・・・[Phase] 5SSERdt3=cut,
+DtJw ・・・・・・・・・・・・・・・・・・
It becomes [phase]. [Phase], UL and LIR are determined from the @formula, that is, the output voltage i from the left and right velocity proportional vibration detectors is calculated. , , the left and right dynamic unbalance UL, υ8 can be measured based on the triple integral value of f.

On the other hand, in the case of a piezoelectric element type pickup, the generated voltage is proportional to the dynamic unbalance amount m7 and ω2, and the integral is 2
This becomes a multiple integral.

Since integration extends the human power signal from the speed proportional vibration detector over time, noise components are removed by integration.

This invention is a speed proportional vibration detector (moving coil type pink-up) in a hard type dynamic balance tester.
Because of the adoption of This means that compared to double integration, the noise suppression effect is greater than that of one integration.

The equations 0 and o are equivalent to the [phase] and equation 2 described later, but the dynamic unbalance υ1. The detailed method for finding υ7 will be explained next.

Substituting the 0.0 weight 0,0 equation into the [phase] equation and ■ equation to find U, , U, respectively, ・・・・・・・・・・・・・・・・・・＠・・・・・・
・・・・・・・・・・・・＠[phase], ■In formula, σ
11. For both υ7, the coefficients applied to the right and left sides are called influence coefficients, but what should be noted here is that MaL/
ω2. Ma. As for I/ω2 of /ω2, as mentioned above, (■'52+-Q)), GiR(ccma□ω)
and among the influence coefficients,
Since the spring constant k C = kL = *) is known, in a hard type dynamic balance tester, even if a speed proportional vibration detector is used as the unbalance detector,
All constants that enter the corrected surface separation calculation are dimensions (distance a
, b, and c).

Since the distances 1a, b, and c can be easily determined without driving the dynamic balance tester, the left and right amplitude displacements are determined by driving the dynamic balance tester and using the left and right velocity proportional vibration detectors. Ma4. Replace ma□ with the above @.

4. Measure the generated voltages ffL and ff based on the formula 0 and calculate the amplitude displacement. The left and right dynamic unbalance TJ + -, j is calculated by corrected surface separation calculation based on the formula
Therefore, l++ can be found.

In soft-type dynamic balance testing machines, in addition to dimensions, the constants that go into the corrected surface separation calculation include the mass 1 moment of inertia, etc. Therefore, each time the test specimen changes, preliminary drive using a trial weight is required. However, in the case of the present invention, no pre-driving is necessary.

Next, we will look at the relationship between the natural frequency of the vibration system and the test rotation speed.

The mass of the test object 1 is M, and the mass (parasitic mass) on the bearings 2L, 2R, and the spring 31.3R other than the test object 1 such as the vibration stand is M.
o, the spring constant is k, and the eccentric center of gravity distance, which is another expression of the magnitude of unbalance, is e, then the centrifugal force F when the test specimen 1 is rotated at an angular velocity ω is F=Meω, where the eccentric weight is The center distance e is r, where the unbalanced mass is m and the unbalanced radius is r.

Bearing amplitude XO at this time (amplitude displacement X-χ.・3in
(ωt-θ)), where the damping coefficient is ρ, di” dt =Meω” cosωt and ωC M +M.

Set ρ ω η 8 ωC and find the solution. In addition, ω. is the natural frequency of this vibration system, and ζ is the damping.

・・・・・・・・・・・・・・・・・・ [Phase] If the unbalance detector is a soft type, ω≧3ω. It holds true in the region of , and in this case, the [phase] equation is approximated as . Also,
In the case of hard type, it is established in the area of ω≦ωc/3,
At this time, the [phase] equation is approximated as follows.

In this way, in the case of hard type pickups, the usable frequency range is limited to the low frequency range, but piezoelectric element type pickups can be used in a wide frequency range on the order of tens to hundreds of times the natural frequency of 6Jc. The noise level was high due to the high response rate.

In contrast, the frequency response region of the speed proportional vibration detector of the present invention is the natural frequency ω. The noise level is low.

Furthermore, the sensitivity of a moving coil pickup, which is a speed proportional vibration detector, can be easily increased by increasing the magnetic flux density of the permanent magnet, increasing the number of turns of the coil, and the like. Therefore, its output impedance is 10-" to 10-' compared to a piezoelectric element type pickup.
By making the voltage sufficiently low (on the order of KΩ), the signal level can be increased (on the order of V).

As described above, the present invention uses a velocity proportional type vibration detector such as a moving coil type pickup as an unbalance detector in a hard type dynamic balance tester, so it is more effective than a conventional piezoelectric element type pickup. Since the output impedance is low and the frequency response region is narrow, the S/N ratio is improved.

F. Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a front view of a dynamic balance testing machine according to an embodiment of the present invention.

Left and right bearings 2L and 2R, which rotatably support the shaft of the specimen rotated by a motor via a heald or the like, are supported by highly rigid springs 3L and 3R. Bearings 2, . The configuration is such that the vibration acting on the 2R is detected by a moving coil type pink amplifier 4L4R as a speed proportional type vibration detector.

Moving coil type pink-up 4L, 4R output signal V, = (A port, +B port, R) ω3. Gi. -(0 units, +
DUR) ω3 is amplified by a preamplifier 5, and the output signal of the preamplifier 5 is triple integrated with respect to time by an integrator 6a and a double integrator 6b with a bandpass filter.

This triple integration makes it 1/ω1, and from the signal, the angular velocity ω
Eliminate the components of the dynamic unbalances UL, U.

In addition to extracting the components that are only involved in the noise, noise is also removed.

The photo mark 7 marked on the surface of the specimen 1 is
Photosensor (reference phase detector) 8 that detects every rotation
is input to the frequency inverter 9, which uses a frequency signal inversely proportional to the frequency of the pulse output for each phase in which the unbalanced mass exists as a chopper signal, and converts the frequency signal into a pan] bus filter. The output signal is output to a double integrator 6b and a synchronous rectifier 10 at the next stage.

Then, the chopper signal is generated by extracting a frequency component synchronized with the rotational speed of the test specimen I, that is, a dynamic unbalance signal, from the pickup signal input to the double integrator 6b with a bandpass filter and the synchronous rectifier 10, and correcting the left balance. The X component and the X component that are perpendicular to each other regarding the plane I and the X component and the X component that are related to the right balance correction surface R are outputted from the synchronous rectifier 10 as a DC voltage.

These left and right X components and X components are cyclically and sequentially switched and A/D converted by an A/D converter with a multiplexer 11, and the digital data is introduced into a CPU 12 in a microcomputer.

CPtJ] 2 includes a memory 13 consisting of a ROM that stores programs and a RAM that stores various data, a display section 14 that displays measurement conditions, measurement results, etc., and input of measurement conditions, measurement data processing method, etc. A keyboard 15 is connected.

The bearing/balance correction surface opening Ma, b, the distance C between the bearings, and the correction radii rL, rR are stored in the memory 13 via the keyboard 15.

The CPU 12 determines the dynamic unbalance amount UL, υ to be corrected, that is, the unbalance mass m+, from these preset data and the two sets of introduced X components and X components.
, mR and the unbalance angle φ1. φ8 is calculated by calculation, the result is stored in the memory 13, and the display unit 1
Display on 4.

Note that FIG. 2 shows details of a circuit portion for one of the left and right pickup signals of the double integrator 6b with a bandpass filter shown in FIG.

A switching transistor T is connected to the input side of an integrator 6b+ consisting of an operational amplifier OP, a capacitor C1, and a resistor R.
, is connected to the operational amplifier OP,.

An integrator 6b consisting of a capacitor Cz and a resistor R2.

The integrator 6b and the integrator 6bz are connected through the switching transistor T2 connected to the input side of the inverter 6b, which is made up of an operational amplifier OP, and resistors R, , R,
are connected to the output stage, and the output of the inverter 6bi is positively fed back to the drain of the switching transistor T.

The first integrated signal from the integrator 6a is input to the source of the switching transistor T2, and the chopper signal from the frequency inverter 9 is input to the gates of the switching transistors T, , T.

When the time constant of the integrators 6b, 6b matches the measurement frequency, the switching transistor TT2 repeats ON and OFF with a duty factor inversely proportional to the measurement frequency.

In the above embodiment, the integrator is configured by hardware, but it can also be implemented by software based on a program.

Effect of G0 invention According to this invention, the following effects are exhibited.

In other words, in a hard type dynamic balance tester, a velocity proportional vibration detector such as a moving coil type pinkup is used as an unbalance detector, so the output impedance is lower than that of a conventional piezoelectric element type pinkup. Since the frequency response can be made low and the frequency response region is narrow, the S/N ratio can be improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a dynamic balance tester according to an embodiment of the present invention, Fig. 2 is a circuit diagram of a double integrator with a bandpass filter, and Fig. 3 is a principle diagram for explaining the operation of the present invention. , is. 1...Test specimen 2,. 2R...Bearing 3L, 3. ...Spring 4L, 4. ...Moving coil type big amplifier (velocity proportional vibration detector) 6a...Integrator 6b...Double integrator with band pass filter (5a,
6 b)...Triple integration means 15...Display section 16...Keyboards a, b...Distance between bearings and balance correction surfaces C...Distance between bearings rL+ rR...Correction radius

Claims (1)

[Claims] (1) In a hard type dynamic balance tester having a highly rigid bearing structure, a speed proportional vibration detector as an unbalance detector that detects the unbalance of a rotating test body;
The output signal of this speed proportional vibration detector is
Dynamic balance comprising means for performing multiple integration, and means for calculating dynamic unbalance from the preset distance between bearings and balance correction surfaces, distance between bearings, correction radius, and the value of the triple integral. Compatible test machine.