CN204462124U - Magnetic flow liquid redispersibility apparatus for quantitatively - Google Patents

Abstract

The utility model discloses a kind of magnetic flow liquid redispersibility apparatus for quantitatively.Device comprises motor, the output shaft of motor is provided with paddle for stirring magnetic flow liquid in beaker and with frequency signal form to gather the dynamic torque sensor of motor speed and moment of torsion, dynamic torque sensor is connected with computing machine via F/V converter.The utility model method can assist the quantitatively evaluating of magnetic flow liquid redispersibility quantitative measuring method realization to magnetic flow liquid redispersibility, to solve the disappearance of current industry in magnetic flow liquid redispersibility quantitatively evaluating.

Description

Magnetic flow liquid redispersibility apparatus for quantitatively

Technical field

The utility model relates to a kind of for the device in magnetic flow liquid redispersibility quantitative measuring method, belongs to magnetic flow liquid redispersibility quantitative test technique field.

Background technology

Magnetic flow liquid (MRF) is a kind of intellectual material, under additional magnetic fields, Ben-Hur (Bingham) plastic solid can rapidly, be reversibly changed into from newton (Newton) fluid, this characteristic has greatly engineer applied and is worth, thus the extensive research of researchers is in the industry caused, current making a search mainly is launched around the performance improving magnetic flow liquid, comprise the performances such as the shear yield strength of magnetic flow liquid, null field viscosity, sedimentation stability and redispersibility, but be not very perfect to the evaluation index of these performances.

Proposed, in the draft about MRF industry standard formulation, to unify the evaluation index of magnetorheological fluid performance by Chinese mechanical industry federation in 2013.The main performance of draft to magnetic flow liquid gives quantitatively evaluating index, and has unified the method for testing of each performance being carried out to quantitatively evaluating.But any method of testing for quantitatively evaluating is not but made for the redispersibility (also known as anti-agglomeration) of magnetic flow liquid, there is no unified testing standard, only regulation is done to the method for testing that magnetic flow liquid redispersibility carries out qualitative evaluation, be defined as " magnetic flow liquid is loaded in closed container; leave standstill after 6 months at room temperature environment; slowly stir magnetic flow liquid with metal or glass stirring rod, differentiate its redispersibility according to the soft degree of settled layer or the complexity of disperseing again ".As can be seen from this regulation, stirring magnetic flow liquid is actually manual type and magnetic flow liquid is dispersed to uniform state by precipitated form, because the soft degree of this person's subjective sensation settled layer or the complexity of disperseing again cannot quantize, can only qualitative analysis, inaccurate, there is very large deviation with the redispersibility of magnetic flow liquid reality.Visible, current industry also exists very large disappearance in the quantitative evaluation of magnetic flow liquid redispersibility.

Thus, in order to improve MRF industry standard, designing a kind of quantitative test technique scheme and carry out quantitatively evaluating to the redispersibility of magnetic flow liquid, is current urgent problem.

Utility model content

The purpose of this utility model is to provide a kind of magnetic flow liquid redispersibility apparatus for quantitatively, this device can be used in magnetic flow liquid redispersibility quantitative measuring method, auxiliary magnetic flow liquid redispersibility quantitative measuring method realizes the quantitatively evaluating to magnetic flow liquid redispersibility, to solve the disappearance of current industry in magnetic flow liquid redispersibility quantitatively evaluating.

To achieve these goals, the utility model have employed following technical scheme:

A kind of magnetic flow liquid redispersibility apparatus for quantitatively, it is characterized in that: it comprises motor, the output shaft of motor is provided with paddle for stirring magnetic flow liquid in beaker and with frequency signal form to gather the dynamic torque sensor of motor speed and moment of torsion, dynamic torque sensor is connected with computing machine via F/V converter.Described computing machine is built with data collecting card.

The utility model has the advantages that:

1) grow out of nothing, the utility model gives the concrete proving installation redispersibility of magnetic flow liquid being carried out to quantitatively evaluating, make the quantitative evaluation that the magnetic flow liquid redispersibility quantitative measuring method completed based on the utility model can effectively realize magnetic flow liquid redispersibility, to solve the disappearance of current industry in magnetic flow liquid redispersibility quantitatively evaluating.

2) the utility model makes magnetic flow liquid redispersibility quantitative measuring method only in magnetic flow liquid quality, the measurement of beaker cross sectional radius, need artificial participation, and other side is computing machine automatically completes, test process automation degree is high, greatly reduce the error that manual operation brings, ensure that the accuracy of gained redispersibility quantitative evaluation result.

3) the utility model help magnetic flow liquid redispersibility quantitative measuring method eliminates the erroneous judgement that people's subjective sensation causes, gained redispersibility quantitative evaluation result precision is high, having great significance to improving magnetorheological fluid performance evaluation, greatly having promoted the development of industry.

4) the utility model apparatus for quantitatively structure is simple, and cost is low, is convenient to produce and safeguard.

Accompanying drawing explanation

Fig. 1 is the implementing procedure figure of magnetic flow liquid redispersibility quantitative measuring method.

Fig. 2 is the composition schematic diagram of the utility model apparatus for quantitatively.

Embodiment

As shown in Figure 1, for the disappearance of current industry in magnetic flow liquid redispersibility quantitatively evaluating and the magnetic flow liquid redispersibility quantitative measuring method proposed comprise the steps:

1) weightometer calculates the quality m of the magnetic flow liquid to be measured loaded in beaker 30;

2) motor 22 is used to drive the magnetic flow liquid in paddle 21 pairs of beakers 30 to carry out Stirring;

3) from stirring initial zero moment to stirring finish time T, the rotating speed of motor in real time 22 and moment of torsion, wherein, at stirring finish time T, the rotating speed of magnetic flow liquid reaches consistent with the rotating speed of motor 22, namely thinks that magnetic flow liquid rotating speed now reaches identical with motor 22 rotating speed;

4) based on step 3) in motor 22 rotating speed that gathers in time period T and moment of torsion, calculate motor 22 in time period T institute work W and stir finish time T time magnetic flow liquid kinetic energy E _k;

5) based on formula (W-E _k)/m calculates the magnetic flow liquid redispersibility Rd for quantitative evaluation.

In reality is implemented, step 1) can specifically comprise:

1-1) weigh beaker 30 quality m _c, the cross sectional radius r of beaker 30 can be measured in practice simultaneously, setting beaker 30 for xsect be circle test container;

1-2) magnetic flow liquid is loaded beaker 30, under room temperature condition (general 20 DEG C are defined as room temperature), leave standstill the gross mass m weighing beaker 30 and interior magnetic flow liquid thereof after 6 months _a;

1-3) by formula m=m _a-m _ccalculate the quality m of magnetic flow liquid to be measured in beaker 30.

In step 2) in, the volume of the magnetic flow liquid loaded in beaker 30 preferably accounts for about 2/3 of beaker 30 capacity.In practical operation, paddle 21 stretches in magnetic flow liquid, is positioned under magnetic flow liquid liquid level.Preferably, in step 2) in, paddle 21 is positioned at the position being approximately magnetic flow liquid degree of depth half below magnetic flow liquid liquid level, the axes normal of paddle 21 in magnetic flow liquid liquid level and axle center overlap with the beaker 30 xsect center of circle.

In force, stirring initial zero moment is motor 22 and brings into operation the moment, stir finish time T and be motor 22 and terminate the time of running, and the rotating speed of setting magnetic flow liquid becomes consistent with the rotating speed of motor 22 when stirring finish time T.And when reality uses motor 22, feature in conjunction with motor 22 can be seen, Stirring leave standstill magnetic flow liquid in this process of homogeneously dispersed state, the rotation speed change of motor 22 is less, and change in torque comparatively large (moment of torsion of motor 22 reduces gradually), and magnetic flow liquid is in finely dispersed process gradually, and its viscous resistance diminishes gradually, moment of torsion diminishes gradually, and torque gradient also diminishes gradually.And when the rotating speed of magnetic flow liquid reaches consistent with the rotating speed of motor 22, motor 22 only needs to keep same rotational speed (same torque) to run.Thus it is rational for judging whether the rotating speed of magnetic flow liquid reaches this fact consistent with the rotating speed of motor 22 with the torque gradient of motor 22.Thus in step 3) middle setting, when the torque gradient Δ M of motor 22 reaches torque gradient threshold value c (c is arithmetic number), can think that the rotating speed of magnetic flow liquid is increased to identical with the rotating speed of motor 22, namely the rotating speed of magnetic flow liquid reaches the degree consistent with the rotating speed of motor 22, and now magnetic flow liquid is considered to be uniformly dispersed.

The torque gradient Δ M of motor 22 is via following formula 1) obtain:

$\mathrm{\ΔM}=\frac{M(t-\mathrm{\Δt})-M\left(t\right)}{M\left(t\right)}---1)$

At above formula 1) in, the motor torque values that M (t) gathers for t, Δ t is the acquisition interval time.

Above-mentioned formula 1) what express is the torque gradient of motor 22 in acquisition interval time in former and later two moment of Δ t, and the torque gradient Δ M of motor 22 should be greater than 0, and t > Δ t.

Formula 1) meaning be, when torque gradient Δ M between the torque value after the torque value and Δ t of a certain moment t of motor equals torque gradient threshold value c, think that now the change in torque of motor 22 is very little, can illustrate that magnetic flow liquid is evenly dispersed substantially, and the meaning of t > Δ t is to eliminate the instability that motor 22 starts rotating speed and moment of torsion instantaneously.

Through validation trial, torque gradient threshold value c is set as 5% is satisfactory.If get c<5%, then because the motor precision of different model is different and the impact of the factor such as noise signal interference in gatherer process, the situation that torque gradient is less than 5% may be there is in magnetic flow liquid whipping process, now magnetic flow liquid is also not dispersed, stir if now stop, then the motor 22 calculated can be caused finally to do work value and be less than the acting actual value disperseed needed for magnetic flow liquid reality.If get c>5%, then along with magnetic flow liquid is uniformly dispersed gradually, torque gradient diminishes gradually, when torque gradient equals c, because c is comparatively large, now magnetic flow liquid is not also uniformly dispersed completely, the motor calculated also can be caused finally to do work value and be less than acting actual value.

In step 4) in, motor 22 in time period T institute work W by following formula 2) obtain:

$W={\&Integral;}_0^T\frac{M\left(t\right)n\left(t\right)}{9550}\mathrm{dt}---2)$

Above formula 2) in, the motor torque values that M (t) gathers for t, the motor speed value that n (t) gathers for t.

Formula 2) by following formula 3), 4) obtain:

$P\left(t\right)=\frac{M\left(t\right)n\left(t\right)}{9550}---3)$

$W={\&Integral;}_0^{T}P\left(t\right)\mathrm{dt}---4)$

Formula 3), 4) in, P (t) represents the power of motor of t.

In step 4) in, based in the rotating speed the stirring finish time T magnetic flow liquid setting identical with the rotating speed of motor 22, the kinetic energy E of magnetic flow liquid during stirring finish time T _kby following formula 5) obtain:

E _k＝mr ²n(T) ²π ²5)

Above formula 5) in, the motor speed value that n (T) gathered for the T moment, namely as the tachometer value of T moment magnetic flow liquid, r is the cross sectional radius of beaker 30.

Suppose:

A. finely dispersed magnetic flow liquid particle and carrier fluid do not have density difference, are namely considered as same material;

B. the angular velocity of magnetic flow liquid in beaker is identical, and namely the linear velocity of magnetic flow liquid linearly increases along radial direction.

Thus, when magnetic flow liquid finally reaches consistent with motor 22 rotating speed due to the effect of paddle 21, based on above-mentioned hypothesis a, b, the kinetic energy of its available rigid body rotation is described, as shown in the formula 6)-8):

$E_k=\frac{1}{2}{\mathrm{jw}}^2---6)$

$j=\frac{1}{2}{\mathrm{mr}}^2---7)$

w＝2πn 8)

Formula 6)-8) in, E _kfor object kinetic energy, j is object rotation inertia, and w is object angular velocity of rotation, and r is beaker cross sectional radius, and n is object rotating speed, and m is mass of object.

Thus, based on above formula 6)-8) above formula 5 can be obtained).

So, based on above formula 2), 5) and formula (W-E _k)/m just can obtain the final expression formula of magnetic flow liquid redispersibility, as shown in the formula 9) shown in:

$\mathrm{Rd}=(W-E_k)/m=({\&Integral;}_0^T\frac{M\left(t\right)n\left(t\right)}{9550}\mathrm{dt}-{\mathrm{mr}}^{2}n{\left(T\right)}^2{\mathrm{\&pi;}}^2)/m---9)$

Formula 9) in, Rd represents the redispersibility of magnetic flow liquid.

The test philosophy that the redispersibility of above-mentioned magnetic flow liquid carries out quantitative test is:

According to 2013 by Chinese mechanical industry federation propose about MRF industry standard formulation draft to magnetic flow liquid redispersibility do the method for testing of qualitative evaluation regulation " magnetic flow liquid is loaded in closed container; leave standstill after 6 months at room temperature environment; slowly stir magnetic flow liquid with metal or glass stirring rod, differentiates its redispersibility according to the soft degree of settled layer or the complexity of disperseing again." analyze; stirring magnetic flow liquid and be actually magnetic flow liquid is dispersed to uniform state by precipitated form, is the process that people does work in essence, but the complexity that people's subjective sensation stirs magnetic flow liquid is exactly that people is to how many sensation of oneself doing work; thus can only qualitative analysis, not energetic.

But as can be seen from afore mentioned rules, be just to obtain dispersed magnetic flow liquid institute work to the key that magnetic flow liquid redispersibility quantizes.Therefore driven by motor paddle is adopted to do work to a certain amount of magnetic flow liquid, it is rational for making magnetic flow liquid realize dispersed, and can see, be rational in the number making motor in the homodisperse process of magnetic flow liquid do work as the quantitatively evaluating index of magnetic flow liquid using what calculate.

But motor does work directly to measure and obtains, therefore the rotating speed of motor in the time period T by measuring setting and moment of torsion is needed to obtain power of motor, again integration is carried out to obtain motor institute work in this time period T, namely via above formula 3 for this time period T to power), 4) obtain above formula 2).

In addition, what describe due to magnetic flow liquid redispersibility is a kind of performance of magnetic flow liquid, it doesn't matter with himself kinetic energy, and motor 22 rotation makes magnetic flow liquid obtain kinetic energy, and thus final redispersibility result should deduct the kinetic energy of magnetic flow liquid (see formula 5)).

Thus eventually through mass unit obtain can truly, rationally, the formula 9 of quantitative response magnetic flow liquid redispersibility exactly).

For above-mentioned magnetic flow liquid redispersibility quantitative measuring method, the utility model proposes the magnetic flow liquid redispersibility apparatus for quantitatively that a kind of auxiliary magnetic flow liquid redispersibility quantitative measuring method effectively performs, as shown in Figure 2, this magnetic flow liquid redispersibility apparatus for quantitatively comprises motor 22, the output shaft of motor 22 is provided with paddle 21 for stirring magnetic flow liquid 10 in beaker 30 and with frequency signal form to gather the dynamic torque sensor 23 of motor 22 rotating speed and moment of torsion, dynamic torque sensor 23 is connected with computing machine 25 via F/V converter 24.

In use, open motor 22, motor 22 drives paddle 21 to stir magnetic flow liquid 10 in beaker 30, in whipping process, dynamic torque sensor 23 gathers moment of torsion and the rotating speed of motor 22 in the frequency form, then the frequency signal collected (high-frequency signal) is sent to F/V converter 24, send computing machine 25 to after frequency signal being converted to by F/V converter 24 analog voltage signal representing Motor torque and rotating speed, by computing machine 25 pairs of motors 22 do work, stir at the end of magnetic flow liquid kinetic energy, magnetic flow liquid redispersibility calculate.

In practice, data collecting card can be housed in computing machine 25.

In practice, the utility model magnetic flow liquid redispersibility apparatus for quantitatively also can comprise the support for fixing beaker 30.

In the utility model device, paddle 21, dynamic torque sensor 23, F/V converter 24 etc. are the existing device of this area, therefore its concrete formation no longer describes.

Table 1 gives and carries out the result of redispersibility test based on above-mentioned magnetic flow liquid redispersibility quantitative measuring method and the utility model device to 3 kinds of magnetic flow liquids below.

Table 1

As can be seen from the above table, redispersibility and the carrier fluid viscosity of magnetic flow liquid, granular mass mark are relevant.Carrier fluid viscosity is larger, and the redispersibility of magnetic flow liquid is poorer.Granular mass mark is larger, and the redispersibility of magnetic flow liquid is poorer.

In practice, the adjuvant that can improve magnetic flow liquid redispersibility in right amount can be added in magnetic flow liquid.If suppose, above-mentioned 3 kinds of magnetic flow liquids add additivated words, and the adjuvant added should be identical.

If do not adopt above-mentioned magnetic flow liquid redispersibility quantitative measuring method, but take the artificial mode stirred to stir according to the regulation of the method for testing in draft, magnetic flow liquid redispersibility being done to qualitative evaluation above-mentioned 3 kinds of magnetic flow liquids, then can feel that the stirring complexity of magnetic flow liquid MRF_1 and MRF_2 is similar, but obviously be greater than magnetic flow liquid MRF_3.But from the composition of magnetic flow liquid, the redispersibility of magnetic flow liquid MRF_1 should be poorer than the redispersibility of magnetic flow liquid MRF_2, but people's subjective sensation does not go out obvious difference, but just accurately can reflect that the redispersibility of magnetic flow liquid MRF_1 is more less better than the redispersibility of magnetic flow liquid MRF_2 by the test result that above-mentioned magnetic flow liquid redispersibility quantitative measuring method obtains, and the redispersibility of magnetic flow liquid MRF_3 is obviously far better than the redispersibility of magnetic flow liquid MRF_1 and magnetic flow liquid MRF_2.

As seen from the above, assist above-mentioned magnetic flow liquid redispersibility quantitative measuring method to carry out the quantitatively evaluating of magnetic flow liquid redispersibility with the utility model and be reasonably, accurately, there is actual value.

On the other hand, as can be seen from Table 1, the absolute value of the difference of the redispersibility of magnetic flow liquid MRF_1 and MRF_2 is less than the absolute value of the difference of the redispersibility of magnetic flow liquid MRF_2 and MRF_3, can disclose the weight of magnetic flow liquid redispersibility influence factor from this point, namely the impact of granular mass mark on magnetic flow liquid redispersibility is greater than the impact of carrier fluid viscosity on magnetic flow liquid redispersibility.

In the art, magnetic flow liquid is the suspended matter that small soft magnetic particles and non-magnetic carrier fluid mix.

The utility model has the advantages that:

1) grow out of nothing, the utility model gives the concrete proving installation redispersibility of magnetic flow liquid being carried out to quantitatively evaluating, make the quantitative evaluation that the magnetic flow liquid redispersibility quantitative measuring method completed based on the utility model can effectively realize magnetic flow liquid redispersibility, to solve the disappearance of current industry in magnetic flow liquid redispersibility quantitatively evaluating.

2) the utility model makes magnetic flow liquid redispersibility quantitative measuring method only in magnetic flow liquid quality, the measurement of beaker cross sectional radius, need artificial participation, and other side is computing machine automatically completes, test process automation degree is high, greatly reduce the error that manual operation brings, ensure that the accuracy of gained redispersibility quantitative evaluation result.

3) the utility model help magnetic flow liquid redispersibility quantitative measuring method eliminates the erroneous judgement that people's subjective sensation causes, gained redispersibility quantitative evaluation result precision is high, having great significance to improving magnetorheological fluid performance evaluation, greatly having promoted the development of industry.

4) the utility model apparatus for quantitatively structure is simple, and cost is low, is convenient to produce and safeguard.

The above know-why being preferred embodiment of the present utility model and using; for a person skilled in the art; when not deviating from spirit and scope of the present utility model; any based on apparent changes such as the equivalent transformation on technical solutions of the utility model basis, simple replacements, all belong within the utility model protection domain.

Claims (3)

1. a magnetic flow liquid redispersibility apparatus for quantitatively, it is characterized in that: it comprises motor, the output shaft of motor is provided with paddle for stirring magnetic flow liquid in beaker and with frequency signal form to gather the dynamic torque sensor of motor speed and moment of torsion, dynamic torque sensor is connected with computing machine via F/V converter.

2. magnetic flow liquid redispersibility apparatus for quantitatively as claimed in claim 1, is characterized in that:

Described computing machine is built with data collecting card.

3. magnetic flow liquid redispersibility apparatus for quantitatively as claimed in claim 1, is characterized in that:

Described magnetic flow liquid redispersibility apparatus for quantitatively comprises the support for fixing described beaker.