CN204142423U - A kind of device of on-line measurement solid of revolution moment of inertia - Google Patents

Abstract

The utility model relates to a kind of device of on-line measurement solid of revolution moment of inertia, belongs to mechanics field.Universal chuck device, is a rotary main shaft with bearing, main shaft is arranged a wire spool, rotate with spindle synchronous, and inertia disc is installed in wire spool side, and opposite side coaxially connects tested solid of revolution; Be fixed on the guide wheel of certain altitude, photoelectric encoder and this guide wheel are coaxially installed; , a flexible rope, one end connects weight, and the other end is wound on this wire spool; The band brake apparatus be made up of cylinder and solenoid valve is by the spindle lock of wire spool place; Computing machine is electrically connected with solenoid valve by capture card, and photoelectric encoder is electrically connected forms signal acquiring system with data collecting card, computing machine order.The utility model solves Constructional Elements Using Falling Methods medium velocity and load factor to the impact of measurement result, improves measuring repeatability and precision.

Description

A kind of device of on-line measurement solid of revolution moment of inertia

Technical field

The utility model relates to mechanical characteristic field, is specifically related to a kind of device of on-line testing solid of revolution moment of inertia, is applicable to measure the moment of inertia that the solid of revolution of assembling was dismantled or completed in inconvenience from working environment.

Background technology

In fields such as exact instrument, engineering machinery, armament systems, Aero-Space, moment of inertia is the important parameter affecting parts and system operation characteristic.Moment of inertia is rigid body the measuring of inertia size in rotation, and the position of its gross mass with rigid body, shape and rotating shaft is relevant.The rigid body more complicated for shape or rotary system be engine crankshaft, automobile clutch such as, and the moment of inertia mathematically calculating it is very difficult, thus multiplex determination of experimental method.Existing moment of inertia method of testing has: compound pendulum, three line Inertia Based on Torsion Pendulum Methods, single pendulum method, torsional oscillation method, said method belongs to moment of inertia off-line test method, measured object need be dismantled from the work system of place and be arranged on related experiment device and test when namely measuring.But in the middle of practical application, a lot of solid of revolution inconvenience is dismantled from residing system, and thus off-line test method is restricted.

Constructional Elements Using Falling Methods directly or indirectly drags tested solid of revolution by weight when measuring moment of inertia and rotates, and calculate the moment of inertia of determinand according to the accekeration in the dropping process of weight, the method is applicable to the moment of inertia value of the solid of revolution that on-line measurement has been assembled.

For eliminating the impact of the moment of resistance in dropping process, traditional Constructional Elements Using Falling Methods adopts the falling bodies equation of twice different acceleration to do and differs from and carries out disappearing unit, thus obtains comparatively accurate moment of inertia value, and its calculation procedure is as follows:

Suppose that determinand moment of inertia is I, weight quality is m ₁, R is coiling radius, f ₀for the moment of resistance, β ₁for the angular acceleration fallen, so system rotation equation is:

Iβ ₁＝m ₁gR-m ₁β ₁R ²-f ₀(1)

Be m by above-mentioned quality ₁weight to be replaced with quality be m ₂weight, other condition remains unchanged, and can obtain new rotation equation:

Iβ ₂＝m ₂gR-m ₂β ₂R ²-f ₀(2)

Wherein: β ₂for the acceleration that second time falls.

Formula (1) and formula (2) are poor cancellation frictional resistance moment f ₀the moment of inertia that can obtain solid of revolution to be measured is:

$I=\frac{(m_1-m_2)\mathrm{gR}-(m_2{\mathrm{\β}}_2-m_1{\mathrm{\β}}_1)R^2}{{\mathrm{\β}}_2-{\mathrm{\β}}_1}---\left(3\right)$

It is more than the fundamental equation that traditional Constructional Elements Using Falling Methods measures moment of inertia.

But there is many weak points in traditional Constructional Elements Using Falling Methods:

(1) traditional Constructional Elements Using Falling Methods is by moment of resistance f ₀be considered as constant value, measuring repeatability and precision are difficult to ensure.Comprise bearing drag and air resistance in falling bodies process, the influence factor of these resistances is numerous, as speed, load etc.Along with the rising of dropping process medium speed, SR square is constantly change.Fig. 1 is Constructional Elements Using Falling Methods inertia measurement mechanism acceleration-rate curve that applicant measures.Obviously, along with the change of speed, the acceleration of falling bodies process is not constant value, thus moment of resistance f ₀be not constant value yet.Meanwhile, adopt the weight of different quality to obtain different acceleration in traditional Constructional Elements Using Falling Methods twice falling bodies process, the load that different quality weight produces guide wheel bearing is different, and thus bearing frictional torque is not identical yet.Visible, the moment of resistance is directly considered as constant value and needs to be improved by traditional Constructional Elements Using Falling Methods.

(2) traditional Constructional Elements Using Falling Methods measuring system is asynchronous with control system, and during repetitive measurement, repeatability is not high.Measuring system is mainly used in writing time and displacement data, and control system is mainly used in controlling weight and starts to fall.In traditional Constructional Elements Using Falling Methods, the survey time and displacement data many by manually completing, even complete the follow-on measurement mechanism of observing and controlling by computing machine, its measuring system and control system are also mutually independently, are difficult to ensure repeatability during test of many times.Thus, a set of clock synchronization system must be set, make the start-up time of measuring system and control system synchronous.

(3) angular acceleration values adopted when traditional Constructional Elements Using Falling Methods calculates inertia is the mean value of several time period acceleration, but several time period length of getting are not identical, and falling bodies process is due to the existence not even acceleration of resistance, thus above-mentioned acceleration mean value does not have clear and definite physical significance, and the velocity amplitude of its correspondence does not conform to the actual conditions yet.

Summary of the invention

The utility model provides a kind of device of on-line measurement solid of revolution moment of inertia, to improve repeatability and the precision of rotation inerttia.

The technical solution adopted in the utility model is: comprise universal chuck device, is a rotary main shaft with bearing, main shaft is arranged a wire spool, rotate with spindle synchronous, and inertia disc is installed in wire spool side, and opposite side coaxially connects tested solid of revolution;

Be fixed on the guide wheel of certain altitude, photoelectric encoder and this guide wheel are coaxially installed;

, a flexible rope, one end connects weight, and the other end is wound on this wire spool;

The band brake apparatus be made up of cylinder and solenoid valve is by the spindle lock of wire spool place;

Computing machine is electrically connected with solenoid valve by capture card, and photoelectric encoder is electrically connected forms signal acquiring system with data collecting card, computing machine order.

Described inertia disc is the standard inertia disc that two identical in quality, moment of inertia is different.

The utility model has the advantages that novel structure, do not change the weight (standard test weight) producing falling, change the standard inertia disc with different moment of inertia, in order to realize the dropping process of twice different acceleration; Institute's accepted standard inertia disc has identical quality and different inertia, object is to eliminate the different impact on rotation inerttia result of bearing load factor, solve Constructional Elements Using Falling Methods medium velocity and load factor to the impact of measurement result, improve measuring repeatability and precision.

Accompanying drawing explanation

Fig. 1 is structural representation of the present utility model, the universal chuck device 5 that in figure, guide roller 1, falling bodies weight 2, photoelectric encoder 3, tested solid of revolution 4, tested solid of revolution are connected with proving installation, wire spool 6, band-type brake cylinder 7, standard inertia disc 8, solenoid valve 9, data collecting card 10, computing machine 11, computing machine 11 is by capture card 10 Controlling solenoid valve 9, and photoelectric encoder 3, data collecting card 10, computing machine form signal acquiring system.

Embodiment

A kind of device of on-line measurement solid of revolution moment of inertia comprises:

Universal chuck device 5 is a rotary main shaft with bearing, main shaft is arranged a wire spool 6, rotates with spindle synchronous, and inertia disc 8 is installed in wire spool side, and opposite side coaxially connects tested solid of revolution 4;

Be fixed on the guide wheel 1 of certain altitude, photoelectric encoder 3 and this guide wheel are coaxially installed;

, a flexible rope, one end connects weight 2, and the other end is wound on this wire spool;

The band brake apparatus be made up of cylinder 7 and solenoid valve 9 is by wire spool 6 place spindle lock;

Computing machine 11 is electrically connected with solenoid valve 9 by capture card 10, and photoelectric encoder 3 is electrically connected forms signal acquiring system with data collecting card 10, computing machine order.

Described inertia disc is the standard inertia disc that two identical in quality, moment of inertia is different.

Application the utility model carries out the method for on-line measurement solid of revolution moment of inertia, comprises the following steps:

One, system inertia is demarcated;

Two, inertia is measured

1) choose a flexible rope, be connected its one end with weight, the other end is wrapped on wire spool, and weight and wire spool are placed in guide wheel both sides;

2) install No. 1 inertia disc 8 in the side of wire spool, opposite side coaxially installs measured object 4;

3) be wound around 6 flexible ropes by wire spool, make weight 2 be increased to predetermined altitude;

4) press start button, start experiment, band brake apparatus, by wire spool 8 place spindle lock, makes it not rotate;

5) time delay a period of time, after weight 2 is stable, unclamp band brake apparatus, drag measured object by weight and accelerate to rotate;

6) unclamp while band brake apparatus instruction sends, computing machine 11 carries out of short duration compensation of delay band brake apparatus actuation time, then starting to record displacement data again;

7) stop experiment when whereabouts displacement reaches setting value, and the data recorded before are saved to computing machine 11;

8) speed data in displacement data calculating dropping process and acceleration information is utilized;

9) in first time falling bodies process, system installs measured object and No. 1 inertia disc, and the standard test weight dragging system being m by quality rotates, and falling bodies equation is:

$(I_1+I_0)\·\frac{{\mathrm{d\ω}}_1}{\mathrm{dt}}=\mathrm{mgR}-m\frac{{\mathrm{d\ω}}_1}{\mathrm{dt}}{R}^2-f({\mathrm{\ω}}_1,L_1)---\left(4\right)$

Wherein I ₁be the moment of inertia value of No. 1 inertia disc, I ₀for measured object and measuring system moment of inertia and, ω ₁for the angular velocity in first time falling bodies process, R is the radius of reel, and g is local gravity acceleration value, L ₁install bearing load during No. 1 inertia disc, the moment of resistance function that f (ω, L) is measuring system self, its major influence factors is speed and load;

10) No. 1 inertia disc be replaced by with it there is equal in quality but No. 2 inertia disc of different inertia, repeat above-mentioned steps (2) to (8), second time falling bodies equation can be obtained:

$(I_2+I_0)\·\frac{{\mathrm{d\ω}}_2}{\mathrm{dt}}=\mathrm{mgR}-m\frac{{\mathrm{d\ω}}_2}{\mathrm{dt}}{R}^2-f({\mathrm{\ω}}_2,L_2)---\left(5\right)$

Wherein I ₂be the moment of inertia value of No. 2 inertia disc, ω ₂for the angular velocity in second time falling bodies process, L ₂bearing load during No. 2 inertia disc is installed;

11) for eliminating moment of resistance f (ω, L), the identical speed point ω in twice falling bodies process is got ₀calculate, i.e. ω ₁=ω ₂=ω ₀; Due to No. 1 inertia disc and No. 2 inertia disc identical in quality, so twice bearing load is identical, i.e. L ₁=L ₂=L ₀so, system inertia and measured object moment of inertia sum I can be calculated according to formula (6) ₀;

So, in twice falling bodies process get calculation level the moment of resistance be all f (ω ₀, L ₀), formula (4) and formula (5) do difference and can draw following inertia formula:

$I_0=\frac{{\mathrm{mR}}^2(\frac{{\mathrm{d\ω}}_1}{\mathrm{dt}}{|}_{{\mathrm{\ω}}_1={\mathrm{\ω}}_0}-\frac{{\mathrm{d\ω}}_2}{\mathrm{dt}}{|}_{{\mathrm{\ω}}_2={\mathrm{\ω}}_0})-(I_2\frac{{\mathrm{d\ω}}_1}{\mathrm{dt}}{|}_{{\mathrm{\ω}}_1={\mathrm{\ω}}_0}-I_1\frac{{\mathrm{d\ω}}_2}{\mathrm{dt}}{|}_{{\mathrm{\ω}}_2={\mathrm{\ω}}_0})}{\frac{{\mathrm{d\ω}}_1}{\mathrm{dt}}{|}_{{\mathrm{\ω}}_1={\mathrm{\ω}}_0}-\frac{{\mathrm{d\ω}}_2}{\mathrm{dt}}{|}_{{\mathrm{\ω}}_2={\mathrm{\ω}}_0}}---\left(6\right)$

I ₀for measured object and measuring system moment of inertia sum, that is:

I ₀＝I+I _S(7)

Wherein: I is the moment of inertia of measured object, I _sfor system moment of inertia,

12) system inertia I _sdrawn by demarcation,

So according to following formula,

I＝I ₀-I _S(8)

Calculate measured object moment of inertia I.

The step that system inertia described in the utility model is demarcated is as follows:

(1) choose a flexible rope, be connected its one end with weight 2, the other end is wrapped on wire spool 6, and weight 2 and wire spool 6 are placed in guide wheel 1 both sides;

(2) install No. 3 inertia disc in the side of wire spool, its inertia value is less than No. 1 inertia disc, and with the system inertia size estimated for reference is mated, now, because system is unloaded, effective inertia mass value is system inertia and No. 3 inertia disc sums;

(3) be wound around flexible rope by wire spool 6, make weight be increased to predetermined altitude;

(4) press start button, start experiment, the band brake apparatus be made up of cylinder 7 and solenoid valve 9, by wire spool 6 place spindle lock, makes it not rotate;

(5) time delay a period of time, after weight is stable, unclamp band brake apparatus, drag measured object by weight 2 and accelerate to rotate;

(6) unclamp while band brake apparatus instruction sends, computing machine carries out of short duration compensation of delay band brake apparatus actuation time, then starting to record displacement data again;

(7) stop experiment when whereabouts displacement reaches setting value, and the data recorded before are saved to computing machine 11;

(8) speed data in displacement data calculating dropping process and acceleration information is utilized;

(9) the falling bodies equation in dropping process is:

$(I_3+I_S)\·\frac{{\mathrm{d\ω}}_3}{\mathrm{dt}}=\mathrm{mgR}-m\frac{{\mathrm{d\ω}}_3}{\mathrm{dt}}{R}^2-f({\mathrm{\ω}}_3,L_3)---\left(9\right)$

Wherein I ₃it is the moment of inertia of No. 3 inertia disc;

(10) No. 3 inertia disc be replaced by and have equal in quality with it but No. 4 inertia disc of different inertia, repeat above-mentioned steps (2) to (9), the falling bodies equation that can obtain No. 4 inertia disc is:

$(I_4+I_S)\·\frac{{\mathrm{d\ω}}_4}{\mathrm{dt}}=\mathrm{mgR}-m\frac{{\mathrm{d\ω}}_4}{\mathrm{dt}}{R}^2-f({\mathrm{\ω}}_4,L_4)---\left(10\right)$

(11) the identical speed point ω in twice falling bodies process is got ₃=ω ₄=ω _0S; Due to No. 3 inertia disc and No. 4 inertia disc identical in quality, so twice bearing load is identical, i.e. L ₃=L ₄=L _0S.So, also equal with the same load point moment of resistance at identical speed point, simultaneous equations (9) and equation (10) cancellation resistance function can obtain:

$I_S=\frac{{\mathrm{mR}}^2(\frac{{\mathrm{d\ω}}_3}{\mathrm{dt}}{|}_{{\mathrm{\ω}}_3={\mathrm{\ω}}_{0S}}-\frac{{\mathrm{d\ω}}_4}{\mathrm{dt}}{|}_{{\mathrm{\ω}}_4={\mathrm{\ω}}_{0S}})-(I_4\frac{{\mathrm{d\ω}}_3}{\mathrm{dt}}{|}_{{\mathrm{\ω}}_3={\mathrm{\ω}}_{0S}}-I_3\frac{{\mathrm{d\ω}}_4}{\mathrm{dt}}{|}_{{\mathrm{\ω}}_4={\mathrm{\ω}}_{0S}})}{\frac{{\mathrm{d\ω}}_3}{\mathrm{dt}}{|}_{{\mathrm{\ω}}_3={\mathrm{\ω}}_{0S}}-\frac{{\mathrm{d\ω}}_4}{\mathrm{dt}}{|}_{{\mathrm{\ω}}_4={\mathrm{\ω}}_{0S}}}---\left(11\right)$

Claims (2)

1. a device for on-line measurement solid of revolution moment of inertia, is characterized in that comprising:

Universal chuck device, is a rotary main shaft with bearing, main shaft is arranged a wire spool, rotate with spindle synchronous, and inertia disc is installed in wire spool side, and opposite side coaxially connects tested solid of revolution;

Be fixed on the guide wheel of certain altitude, photoelectric encoder and this guide wheel are coaxially installed;

, a flexible rope, one end connects weight, and the other end is wound on this wire spool;

The band brake apparatus be made up of cylinder and solenoid valve is by the spindle lock of wire spool place;

Computing machine is electrically connected with solenoid valve by capture card, and photoelectric encoder is electrically connected forms signal acquiring system with data collecting card, computing machine order.

2. the device of a kind of on-line measurement solid of revolution moment of inertia according to claim 1, is characterized in that: described inertia disc is the standard inertia disc that two identical in quality, moment of inertia is different.