JPH0346539A - Damping coefficient measuring instrument - Google Patents

Abstract

PURPOSE:To calculate the viscous resistance of a substance which gets out of shape easily such as yogurt by giving forced rotational vibration to a container in which an object to be measured is contained, taking out its damping process by an electric signal and deriving a damping factor of the vibration. CONSTITUTION:By a supporting arm 13 of a support 12 erected on a base 11 of an instructing device 10, a supporting shaft 22 is supported, and an object placing base 20 becomes freely rotatable. In this state, a container in which an object to be measured is contained is placed on its object placing plate 21 and fixed so that its position is not shifted. Subsequently, the whole object placing base 20 is rotated by a prescribed angle against a plate spring 33 of a turning energizing device, and brought to free vibration therefrom. In such a way, the vibration becomes damping vibration, and its amplitude or turning period is detected by a detector 40. Next, when a damping coefficient of its detection value is brought to data processing by a microcomputer, etc., a viscous resistance of the object to be measured is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an attenuation coefficient measuring device, and particularly to one suitable for measuring the viscous resistance of semi-solid or semi-liquid materials such as yogurt.

[Prior art and problems to be solved by the invention] There are four types of conventional damping coefficient measuring instruments, for example, instruments for measuring viscous resistance, that is, viscometers, such as capillary viscometers, rotational viscometers, and vibrational viscometers. be.

However, these measuring instruments all measure semi-solid objects,
It is not suitable for semi-liquid materials, such as yogurt, which easily lose their original shape when external force is applied. In other words, a capillary viscometer cannot be used with this type of product because it does not produce a capillary phenomenon, whereas a rotational viscometer fills the space between a movable outer cylinder and a fixed inner cylinder with the object, and rotates the movable outer cylinder at a constant angular velocity. In order to measure the couple due to viscous resistance,
If the object breaks at the contact surface between the outer cylinder and the object, only a couple that is different from the original viscous resistance can be expected. In order to measure the damping coefficient of the vibration by vertically vibrating the object, the object would be crushed by the vibrator, and it was not possible to obtain the original viscous resistance value.

[Means for Solving the Problems] The present invention aims to solve the above-mentioned conventional problems, and includes storing a semi-solid or semi-liquid substance such as yogurt in a container, and Forced rotational vibration is applied, and the damping process is extracted using an electrical signal to determine the vibration damping rate, thereby making it possible to calculate the viscous resistance.

The present invention will be described with reference to FIGS. 1 to 7, which correspond to embodiments. The support device 10 includes support arms 13 and 13 fixed horizontally to columns 12 erected on a base 11. The support arm 13 is provided with a pair of upper and lower pivot bearings 24,24. In addition, the stage 20 has a support shaft 2 with the center of the lower surface of the stage plate 21 on which the container 50 containing the object to be measured is placed.
The support shaft 22 has openings 23, 23 through which the support arm 13 is inserted, and a pair of upper and lower pivot pins 14, 14 protrudes into the openings 23. .14 are respectively supported by the pivot-shaped bearings 24 and 24, and are able to rotate freely with minimal braking due to friction during rotation. The rotational biasing device 30 is a leaf spring 33
A roller 36 is provided with a center portion of the plate spring 33 fixed to the lower end of the support shaft 22, and a roller 36 whose position is variable near both end portions.
..., and by changing the support positions of both ends of the leaf spring 33, it is possible to apply various damped rotational vibrations to the support shaft 22. Furthermore, the detector 40 detects and outputs the rotation amplitude or rotation period of the support shaft 22.

Here, the principle of the present invention will be explained with reference to FIGS. 7 to 10.

In Fig. 7, J is the inertia coefficient of the inertial body 1 (Kg-cm・s”)
, C is the viscous resistance coefficient k (Kg-cm/rad/S) for the rotational movement of the inertial body 1 by the dashbot 2
is the spring constant (Kg-cm/rad) of the spring 3, and if we show a typical example of rotational motion with one degree of freedom, then Jd"θ/dt"+Cdθ/dt+θ=M(t)
...(1).

The damped free vibration equation J(d
”θ/dt2) +C(dθ/dt)The general solution for θ=O is given as follows: θ=Cr e
"' + Cg e "t-(21 However, CI and C2 are arbitrary constants, and S3 and S2 are the solutions of the equation % formula %. That is, SI□ = - (CI 2J) ± (CI 2J) 2 - (k/J
) Here, the form of equation (2) differs depending on whether S+ and t are real numbers or complex numbers, but when (CI 2J) < (k/J), it is a damped oscillation. That is, 12 = -(C/2Jl±j(k/J) -(C/2J)"
Since it includes imaginary numbers, the solution includes e J t, and e
From the relationship ' = cos a + j sin a, θ = e-(C/2''t(Cr・cos q t+cz si
n q t) However, q= (k/ J) - (CI 2J)"CI'=CI
+C2, C2'=j (CI - C2).

This solution is a combination of a decreasing exponential curve and a harmonic vibration curve, and as shown in Figure 9, 6- I C/ @ J l
' and-〇-1c/! This is a damped oscillation that oscillates while decreasing between Jl t .

In addition, when (CI 2J)” > (k/J),
Since both S+ and S- are negative real numbers, e1te821
Both represent a decreasing exponential curve. Also (CI 2J)
” = (k/J), then S,,52=-(C/
2J), which is an equal root of real numbers and is also non-periodic.

However, even if the damping is a little smaller than this, it will result in vibration, so as a state at the boundary between vibration and no period, (C/ 2J) 2
= (k/m)=ω.

The critical damping constant cc for the state is C,=2Jω.

(ω is the resonant frequency).

In the damped free vibration state as shown in Fig. 8, take the amplitude ratio of successive vibrations, the nth amplitude is an, and the n+1st amplitude after one period (T=2π/q) is a n.
41, an / an++ = e (C/
2J) T:=6+C/JQI=const.

Therefore, it is a constant value no matter which peak of vibration is taken. In other words, the amplitude decreases in a geometric progression.

Taking the logarithm of this ratio, δ=log(a,/an++) =xC/
It becomes Jq.

The damping coefficient measuring device according to the present invention calculates this δ, that is, the logarithmic damping rate, from the measurement data, and thereby calculates the viscous drag coefficient C, as follows: C-(δJ/π) ・q = (δJ/π) ・(k/J) −(c/2
J) When calculating C from 2, it becomes C=2δJk/ (4π2+δ2).

Therefore, the inertia rate J is when nothing is placed on the loading plate 21 and when the container 50 is placed on the loading plate 21. and Jl
, the spring constant k can be made common and known, and the influence of friction on rotational vibration can be minimized, the swinging rotation of the support shaft 22 is detected by the detector 40, and the logarithmic damping rate δ is determined from the detected value. By determining , the viscous drag coefficients C8 and C1 under the above two conditions are obtained, and the viscous drag coefficient of the object in the container 50 is calculated from the difference between the two values.

Here, the inertia rate J of the entire system when nothing is placed on the loading plate 21. And the spring constant is calculated as follows using an additional mass with a known inertia factor J2.

That is, generally the resonant frequency ω of the rotational kinematics meter. Ha, ω. It is expressed as = ni/J.

The resonant frequency ωn1 with no added mass is ω,=/
J.

Resonant frequency ω with added mass. 2 is ω. 2=to/(JO+J2). Therefore, from the above two equations, ω. 1′/ωn2” = (JO+J2)/jo
(3) becomes. Therefore, Jo = (ω., ′/(ω, −ω112”)
) to XJ2 = (ω, ′・ω,, 2”/ (ω, −
ωna”l X J 2.

In addition, the rotation period T of the stage 20 is measured, and T=2x/
The viscous drag coefficient C can also be determined from qq=(k/J)-(C/2J)2=2π/T. That is, from these two equations, C=2J(k/J)-(2π/T)2.

Here, the rotation biasing device 3o of the present invention uses a leaf spring 33 in place of the spring 3 shown in FIG. 7, and has the system shown in FIG. It is thought to consist of Therefore, considering the spring constant of one cantilever beam system as shown in FIG. 10, the spring constant of the leaf spring 33 is k. is ko=F/X=3E/43. However, F is the load applied to the end of the leaf spring 33 (Kg/
cm"), x is the amount of deflection of the spring end (cm), E is Young's modulus (Kg/cm2), I is the moment of inertia of area (cm-31, and Q is the length of the leaf spring.

In the case of the present invention, the leaf spring 33 has a torsional torque T of the support shaft 22.
(Kg-cm), and the relationship between load F and torsion torque T is F=T/(L/2)=2T/L, so (L
is the total length of the leaf spring 33), and in the case of this system, the overall spring constant is K=2. In any case, since this spring constant is inversely proportional to the spring length and fl to the third power, if the support position by the roller 36 is varied, the above relationship will be satisfied. Therefore, various test conditions can be created by varying the spring constant.

Of course, calculation of the various states described above can be easily performed using a data processing device using a microcomputer or the like.

[Operation] Next, the operation will be explained. The container 50 containing the object to be measured is placed on the mounting plate 21 and fixed so as not to shift, and the entire mounting plate 20 is rotated by a predetermined angle against the biasing force of the rotational biasing device 30. Let it vibrate freely from the state. This vibration then becomes a damped vibration as described above, and the detector 40 detects its amplitude or rotation period. Then, the logarithmic attenuation rate, ie, the attenuation coefficient, of this detected value by the detector 40 is processed by a microcomputer or the like to calculate the viscous resistance of the object to be measured. The damped vibration conditions are determined by changing the support position of the leaf spring 33 to vary the spring constant, and measurements are performed in the same manner as above.

[Example] Embodiments of the present invention will be described below based on the drawings.

In the figure, 10 is a support device, 20 is a stage, 30 is a rotation urging device, and 40 is a detector.

The support device 10 has a thick long column-shaped support 12 erected at the center of the rear edge of the base 11, and supports 12 at each corner of the front edge.
A screw 15 for leveling is provided at the rear of the frame.

Two support arms 13.13 are horizontally fixed to the column 12, and a pivot pin 14 is attached to each end of the support arm 13.13.
are vertically protruding in opposite directions. In addition,
The number of support arms 13 may be one, or three or more.

The stage 20 is composed of a thin disc-shaped stage plate 21 and a support shaft 22 attached to the center of the lower surface of the stage plate 21 .

The support shaft 22 is a hollow cylinder, with three cylindrical openings 23, 2 in the middle.
3 is a provision. This aperture 23.23 is connected to the support arm 1
The opening is slightly larger than the cross-sectional area of the support arm 13 at a position corresponding to the support arm 13.13 so that the support arm 13.13 can be inserted through the support arm 13.13 with plenty of room. In addition, mounting seats 25 and 26 are fitted into and fixed to the upper and lower ends of the support shaft 22, respectively, and the mounting plate 21 is fixed to the upper mounting seat 25, and the lower mounting seat 26 is rotatably biased. The device 30 is installed.

A spring 27 and a bearing 24 are embedded in the upper mounting seat 25, and the spring 27 biases the bearing 24 to protrude downward. The bearing 24 is also fixed to the lower mounting seat 26 with the bearing 24 facing upward.

Then, the support arm 13.
13 is inserted into the support device, and the bearings 24 and 24 are connected to the pivot pins 14 of the support arm 13, respectively.
．． 14. That is, the tip of the bearing 24 matches the top of the recess of the pivot pin 14 to form a so-called pivot bearing, and the combination is such that no friction occurs when the support shaft 22 is rotated. Also, the upper pivot pin 14
When the bearing 24 is engaged with the bearing 24, the spring 27 urges the bearing 24 to protrude downward, and the reaction force of this urging force causes the lower bearing 24 to push up the lower pivot pin 14. Therefore, the support shaft 22 is sufficiently supported only by the biasing force, and the upper and lower pivot pins 14
It is rotatable in the horizontal direction with the line connecting the contact point of the bearing 24 and the tip of the bearing 24 as the rotation axis. However, since the diameter of the opening 23 is only slightly larger than the cross-sectional area of the support arm 13, the rotation angle of the support shaft 22 is limited. In the yogurt viscosity resistance measurement test conducted by the inventor, the rotation angle of the support shaft 22 was 5.
The degree was appropriate.

The rotational biasing device 30 is attached to a mounting seat 26 provided at the lower end of the support shaft 22.
A linear groove 31 is provided on the lower end surface of the plate spring 33, and a plate spring 33 sandwiched between a pair of liners 32 is fitted and fixed into this groove 31, and is supported by roller guides 34 at both ends of the plate spring 33.

The roller guide 34 is constructed by attaching a roller holder 37 containing a pair of rollers 36 to a fixed base 35 erected on the base 11. A gap is provided between the rollers 36 and 36 at the tip end 37a of the roller holder 37. A groove 38 is formed so as to allow the plate spring 33 to pass through the groove 38, and the leaf spring 33 is inserted such that both ends thereof pass through the groove 38 and protrude outward.

Further, the roller holder 37 has a tip end portion 37a that holds the roller 36 in a tapered trapezoidal shape, and the fixing base 35 has a corresponding trapezoidal notch groove 35a. For this reason,
By fitting and fixing the tip portion 37a of the roller holder 37 into the notch groove 35a of the fixing base 35, the roller 36 can be easily positioned with respect to the leaf spring 33 without using a measuring instrument or the like. Note that the width of the groove 38, particularly the opening portion on the support shaft 22 side, is preferably widened slightly in consideration of displacement in the width direction due to deflection of the leaf spring 33.

On the side of the fixed base 35 where the roller holder 37 is not provided,
A pair of holes 35b and 35c are provided respectively, and a guide shaft 60 is inserted through the holes 35b and 35c on the support shaft 22 side. The other hole 35c is a threaded hole, into which a screw shaft 61 for varying the position is screwed. Screw shaft 61
A bevel gear 62 is formed at the end, and each has a common right-hand thread. In addition, these guide shafts 60,
The screw shaft 61 is inserted through and supported by a support frame 63 fixed on the base plate 11, and each bevel gear 62 is screwed into a bevel gear 65 provided at the tip of an adjustment knob 64 provided on the support frame 63. There is.

Therefore, when the adjustment knob 64 is turned, the bevel gear 62.65
The screw shaft 61 rotates due to the engagement, and the screw shaft 61.6
1 have opposite threads, the fixing bases 35 and 35 move in opposite directions along the axis of the screw shaft 61, and the distance between them widens and narrows, changing the supporting position of the leaf spring 33 by the rollers 36. It is designed to let you do so.

For example, a potentiometer can be used as the detector 40. In the illustrated example, an arm 41 is attached to the lower end surface of the mounting seat 26 on the lower side of the support shaft 22, and the arm 41 and the detector 40
The rotational displacement of the support shaft 22 is taken out as an electric signal by connecting the support shaft 22 with the arm 42 using a bottle. Of course, the detector 40 may be of any type, but like the rotation urging device 30, it is desirable that the detector 40 has as little frictional resistance to the rotation of the support shaft 22 as possible.

In the figure, reference numeral 70 denotes a stopper device, which is attached to the upper end of the support column 12 to prevent rotation of the stage 20 during transportation. That is, in this stopper device 70, a stopper 72 passes through the inside of the case 71, and in a situation where it is difficult for the loading stage 20 to rotate, the tip of the stopper 72 is latched to the bin 21a protruding below the loading plate 21. to fix the position of the loading plate 21, and when rotating the loading table 20, use the stopper 72.
is further pushed into the lower surface of the loading plate 21 to release the engagement between the stopper 72 and the bin 21a.

Next, the operation and operation of the apparatus of this embodiment when measuring the viscosity of the object to be measured stored in the container 50 will be explained.

First, the container 50 containing the object to be measured, such as yogurt, is placed and fixed on the mounting plate 21, and the mounting plate 21 is rotated by a predetermined angle, for example, 5 degrees. Then, the support shaft 22 also rotates, and accordingly, the plate spring 33 of the rotational biasing device 30 is twisted at its center and deformed from the state shown in FIG. 4 to the state shown in FIG. 5.

When the loading plate 21 is released in this state, the loading table 20 and the support shaft 22 begin to rotate in the opposite direction to the previous rotation operation direction due to the restoring force of the deformed plate spring 633, and then the plate spring 33 The support shaft 22 rotates back and forth with the free damping vibration, and an electric signal corresponding to the rotational displacement of the support shaft 22 is output from the detector 40.

The vibration curve drawn by the output of the detector 40 at this time becomes a damped vibration curve as shown in FIG. system, it is different from the damped vibration curve when nothing is placed on the stage 20. Therefore, if you collect vibration data in advance when nothing is placed on the stage 20, you can compare it with the vibration data when the container 50 is added and perform the measurement as described above. The viscous resistance of an object can be calculated.

Spring constant k of the leaf spring 33. In order to vary this, it is only necessary to turn the adjustment knob 64 and move the fixing bases 35, 35 in opposite directions along the axis of the screw shaft 61. Then, the space between the fixed bases 35 and 35 widens and narrows, and the supporting position of the leaf spring 33 by the roller 36 changes, resulting in a spring constant k. can change and test conditions can be changed.

Note that since the device of the present invention does not directly measure viscous resistance but outputs damped vibration data, the measurement target is not limited to viscous resistance.

[Effects of the Invention] Since the attenuation coefficient measuring device according to the present invention is as described above, it can be used for measuring objects such as yogurt, for which it has been troublesome to measure viscous resistance etc. in the past. By simply applying a slight forced vibration without directly applying an external force, it is now possible to easily collect electrical measurement data to measure the damping state of the vibration, and the spring constant of the leaf spring can be varied in various ways. This has the effect of making it easier to perform measurements under many test conditions.

[Brief explanation of drawings]

FIG. 1 is a perspective view of one embodiment of the present invention, FIG. 2 is a partially sectional side view of the same, FIG. 3 is a partially sectional plan view of the same, and FIGS. 4 and 5 are of the same rotational biasing device. FIG. 6 is a perspective view of the detector, and FIGS. 7 to 10 are explanatory views showing the principle of the present invention. IO = Support device 11: Base 12: Strut 13: Support arm 14: Pivot pin 20: Load stage 21: Load plate 22: Support shaft 23: Opening 24: Bearing 30: Rotation biasing device 40: Detector 33: Leaf spring 50: Container

Claims (1)

[Claims] A support arm is fixed horizontally to a support erected on a base,
The support device includes a support device in which a pair of upper and lower pivot-shaped bearings are provided on the support arm, and a support shaft supports the center of the lower surface of a mounting plate for placing a container containing an object to be measured, and the support shaft is attached to the support arm. A stage is provided with a pair of upper and lower pivot pins at positions corresponding to the pivot-shaped bearings, and the pivot pins are supported by the pivot-shaped bearings to be rotatable; a rotational biasing device, which includes leaf springs supported with variable support positions, and which applies damped rotational vibration to the support shaft; and a detection device which detects and outputs the rotational amplitude or rotation period of the support shaft. Attenuation coefficient measuring device consisting of a device.