A single-drive energy-saving horizontal elliptical vibrating screen and its parameter determination method

Abstract

The application belongs to the technical field of vibrating screening devices, and discloses a single-machine driving energy-saving horizontal elliptical vibrating screen and a parameter determination method thereof. The single-machine driving energy-saving horizontal elliptical vibrating screen comprises a vibration exciter, an outer mass body, an inner mass body, a shearing rubber spring and a vibration isolation spring. The vibration isolation spring is connected to a foundation and a main mass body. The vibration exciter is located at the centroid of the outer mass body and is composed of an eccentric rotor and an induction motor. The vibration exciter rotates around the center of its rotation axis, thereby generating a vibration excitation force to make the inner mass body generate a certain vibration intensity. The movement track of the inner mass body is an elliptical movement. According to the use requirement, a corresponding number of inner mass bodies can be installed to improve the production rate and reduce the power consumption, thereby realizing the engineering application value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vibrating screening devices, in particular to a single-machine-driven energy-saving horizontal elliptical vibrating screen and a parameter determination method thereof. BACKGROUND

[0002] The technology of vibrating screens has gradually matured at the present stage and is widely used in the sand and gravel aggregate industry, as well as in mines, steel plants, food, chemical industry, petroleum, tunnel engineering, etc., to realize the classification of various materials. Therefore, there are many types of vibrating screens, including vibrating screens that perform screening in a single-frequency driving manner, vibrating screens that use single-mass super-resonance technology, etc., but these vibrating screens have different defects. For example, the single-mass vibrating screen in CN102744203A has a working frequency far exceeding the resonance frequency, and requires a large excitation force, so the power consumption also increases, and when the vibrating screen starts and stops through the resonance zone, the device will produce a large vibration, which will cause the machine to run unstably, be easily damaged, and reduce its service life. Thus, resources are wasted and production costs are increased. In addition, the existing material screening methods mostly require multiple screening to separate and collect materials of different particle sizes, which is low in screening efficiency and causes the mixing of coarse and fine materials after screening, which cannot meet the production needs. Therefore, it is necessary to design a vibrating screening device to improve the screening quality and make the production efficient. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a single-machine-driven energy-saving horizontal elliptical vibrating screen and a parameter determination method thereof, which utilizes a double-mass high-frequency vibrating fine screen based on sub-resonance technology. This double-mass high-frequency vibrating fine screen can increase the screening area of the entire machine, reduce energy consumption, and improve the screening efficiency.

[0004] Taking the exciter on the outer mass as the research object, a dynamic model is first established, and the motion differential equation of the system is solved by applying the Lagrange equation. Since the system is single-machine-driven, the system itself is very stable, and then the natural frequency of the main vibration system is solved. The steady-state responses of the inner and outer masses in the x and y directions, as well as the elliptical trajectory equation of the inner mass, are solved. Finally, the high and low order natural frequencies of the system under the action of external excitation are solved, thereby determining the working range of the machine. The corresponding working parameters and motion trajectories are simulated.

[0005] The technical scheme of the present application is as follows: a single-machine driving energy-saving horizontal elliptical vibrating screen, comprising: a vibration exciter 5, an outer mass body 2, an inner mass body 3, a shear spring 4, and a vibration isolation spring 1; the vibration isolation spring 1 is symmetrically connected between the foundation 6 and the outer mass body 2; the vibration exciter 5 comprises an eccentric rotor and an induction motor, and is located at the centroid of the outer mass body 2; the vibration exciter 5 rotates around the central axis of itself to generate a vibration excitation force, drives the horizontal elliptical vibrating screen system to generate vibration intensity, and drives the inner mass body 3 to realize elliptical motion; the inner mass body comprises a plurality of mass bodies, each of which is connected to the inner base of the outer mass body 3 through a plurality of shear springs 4; all the shear springs 4 have the same inclination angle; the adjacent mass bodies are equidistant.

[0006] The outer mass body 2 is a vibrating screen body, and the inner mass body 3 is a screen mesh; the shear springs 4 are distributed at both ends of the mass body; the feed inlet and the discharge outlet of the vibrating screen body are symmetrically distributed with the centroid of the vibrating screen body as the origin.

[0007] When the inclination angle of the shear spring 4 is 0-90 degrees, the vibration exciter 5 rotates counterclockwise at this time, the feed inlet is located at the upper right of the vibrating screen body, and the discharge outlet is located at the lower left of the vibrating screen body; when the inclination angle of the shear spring is 90-180 degrees, the vibration exciter 5 rotates clockwise at this time, the feed inlet is located at the upper left of the vibrating screen body, and the discharge outlet is located at the lower right of the vibrating screen body.

[0008] A parameter determination method of a single-machine driving energy-saving horizontal elliptical vibrating screen, comprising the following steps:

[0009] Step 1, establishing a dynamic model and a system motion differential equation;

[0010] A fixed coordinate Oxy is set, the rotation center of the vibration exciter 5 is O, and the corresponding phase is represented as The entire horizontal elliptical vibrating screen system has three degrees of freedom, which are vibration in the x direction, vibration in the y direction, and swing ψ around the centroid;

[0011] x, y, ψ are selected, as generalized coordinates, the motion differential equation of the horizontal elliptical vibrating screen system is derived based on the Lagrange equation as follows:

[0012]

[0013]

[0014]

[0015]

[0016]

[0017] wherein,

[0018] M1 = m1 + m2 + m3 +... + m n M2 = m0 + m v M = M1 + M2

[0019]

[0020] β = 0° - 90°

[0021] l x = l1 cos β, l y = l2 cos β

[0022] In the formula, M is the total mass of the horizontal elliptical vibrating screen system; m v is the mass of the outer organelle; m0 is the mass of the eccentric rotor of the exciter; m i is the mass of the screen, i = 1, 2, 3…n; J is the rotational inertia of the entire horizontal elliptical vibrating screen system; J0 is the rotational inertia of the exciter; J m is the rotational inertia of the inner organelle, the outer organelle and the induction motor of the exciter; l e is the equivalent rotating radius of the horizontal elliptical vibrating screen system; r is the eccentricity of the exciter; f0 is the shaft damping coefficient of the induction motor; T0 is the electromagnetic output torque of the induction motor; β is the installation angle of the shear spring; k x , k ψ are the spring stiffness of the horizontal elliptical vibrating screen system in x and ψ directions, respectively; k, k y are the spring stiffness of the inner organelle and the outer organelle in y direction, respectively; f x , f ψ are the damping coefficient of the horizontal elliptical vibrating screen system in x and ψ directions, respectively; f 1y , f 2y are the damping coefficient of the inner organelle and the outer organelle in y direction, respectively; l1 is the straight line distance from the connection point of the vibration isolation spring 6 and the outer organelle to the center of mass of the vibrating screen; l2 is the horizontal distance from the connection point of the vibration isolation spring 1 and the outer organelle to the center of mass of the vibrating screen; β is the inclination angle of the shear spring; is the first order time derivative; is the second order time derivative;

[0023] Step 2, calculate the natural frequency, steady-state response and trajectory equation of the horizontal elliptical vibrating screen system;

[0024] Step 3, calculate the high-order natural frequency and low-order natural frequency of the horizontal elliptical vibrating screen system.

[0025] The natural frequency, steady-state response and trajectory equation of the horizontal elliptical vibrating screen system are calculated as follows;

[0026] In the steady state, do not consider kx and k y are all less than k, ignoring the damping constant f of the external mass 2y ;

[0027] In summary, formula (1) and formula (2) are simplified to

[0028]

[0029]

[0030] In the formula

[0031] M1′=M1,

[0032] Ignore k y , so

[0033] M2′=M2

[0034] Arranging equations (6) and (7), we get:

[0035]

[0036] Where,

[0037] y3=y1-y2

[0038] Among them, M3 is the induced mass of the horizontal elliptical vibrating screen system, y3 is the relative displacement of y1 and y2;

[0039] According to formula (8), the natural frequency ω of the horizontal elliptical vibrating screen system is deduced n ;

[0040]

[0041]

[0042] Where,

[0043]

[0044] From the above formula, we can see that when ω m0 / ω n =1, the horizontal elliptical vibrating screen system resonates, and y 12 has a maximum value, that is, the amplitude is

[0045]

[0046] The absolute motion response of the horizontal elliptical vibrating screen system in the x, y and ψ directions is derived as follows by the transfer function method:

[0047]

[0048] When ε a ε cj +ε b ε d > 0,

[0049]

[0050] When ε a ε cj +ε b ε d < 0,

[0051]

[0052] It can be seen from the above that the maximum displacement of the endoplasm in the x direction is The maximum displacement in the y direction is

[0053]

[0054] The elliptical trajectory equation of the endoplasm is:

[0055]

[0056] In the formula,

[0057]

[0058] In the formula, x1, y1, ψ1 are the absolute motion responses of the endoplasm in the x, y, and ψ directions, respectively.

[0059] The calculation of the high-order natural frequency and the low-order natural frequency of the horizontal elliptical vibrating screen system is specific to

[0060] The characteristic value equation of the horizontal elliptical vibrating screen system and the two corresponding high-order natural frequencies and low-order natural frequencies are obtained from formula (1) and formula (2) respectively

[0061] (k-ω 2 M1)(k+k y -ω 2 M2)-k 2 = 0 (14) Solving,

[0062] In the formula, b = M1(k y +k) + M2k, c = [M1(k+k y )] 2 +(M2k) 2 + 2M1M2k(k-k y );

[0063] Ignore parameter k 1y After that, we get ω1=ω0; from the above formula, we can know the two frequencies of the horizontal elliptical vibrating screen system, and ω2<ω1=ω0; adjust the operating frequency of the motor to make it less than the natural frequency ω0 of the horizontal elliptical vibrating screen system to achieve sub-resonance operation of the vibrating screen.

[0064] Beneficial effects of the present invention:

[0065] (1) The present invention adopts a single-machine driven double-mass horizontal elliptical vibrating screen, which has unique high efficiency and working performance. Compared with the traditional direct drive design, the double-mass drive system can make the screen movement amplitude larger under the same conditions, thereby better reducing power consumption. In addition, the elliptical screening motion has a higher screening efficiency than the horizontal screening motion. In addition, different numbers of screens of different particle sizes can be set according to needs to achieve the work of simultaneous screening of multiple particle sizes, which also improves work efficiency;

[0066] (2) The sub-resonant dual-mass vibrating screen of the present invention uses sub-resonance technology, and the vibration frequency is lower than the natural frequency of the vibration system. Sub-resonance occurs when the equipment is working. Compared with the single-mass vibrating screen, the required excitation force is smaller and the power consumption is lower. The startup and shutdown processes do not pass through the high-order resonance zone, which reduces damage to the machine and prolongs its service life.

[0067] (3) By setting the excitation shear rubber spring and the vibration isolation spring, it is possible to drive a larger screen body with a very small excitation force, amplify the working amplitude through the excitation spring system, and will not affect the screening performance as the material load changes. The vibration isolation spring can not only support the vibration source box, but also reduce the dynamic load transmitted to the foundation or structural frame. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is the dynamic model diagram of the horizontal elliptical vibrating screen system.

[0069] In the figure: 1. Vibration isolation spring; 2. Outer mass; 3. Inner mass; 4. Shear spring; 5. Vibrator; 6. Foundation.

[0070] The meaning of each parameter in the figure: O - the center of the entire system; ——exciter rotation phase angle; m0——exciter mass; r——exciter eccentricity; k x ——spring stiffness coefficient in the x direction; k y ——Spring stiffness coefficient in the y direction; k——Stiffness of the shear rubber spring; β——Inclination angle of the shear rubber spring; n——Number of screens.

[0071] Figure 2(a) shows the motor speed simulation results;

[0072] Figure 2(b) shows the simulation results of the motion trajectories of the inner and outer particles;

[0073] Figure 2(c) shows the simulation results of the inner and outer mass displacements in the y direction;

[0074] Figure 2(d) shows the simulation results of the displacement of the exomast in the x-direction. DETAILED DESCRIPTION

[0075] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0076] like Figure 1 As shown, the vibrator 5 is composed of an eccentric rotor driven by a motor and is arranged at the center of mass of the vibrating screen body; the vibrator 5 rotates at a fixed speed when working. The vibrator 5 is connected to the vibrating screen body so that it produces circular motion; the internal screen 3 is fixed to the external box body by a shear rubber spring 4 tilted at a certain angle. Different numbers of screens 3 can be arranged according to different usage requirements. The distance between each screen 3 is equal, and they are symmetrically distributed in the vertical direction to maintain overall balance. The feed port of the vibrating screen is located on the upper right side of the external screen 2, and the discharge port is located on the lower left side of the external screen 2. There are 4 vibration isolation springs 1, which are installed on the bottom of the external box body 2 in the front, back, left and right directions, and the external box body 2 is installed on the foundation 6.

[0077] The vibrator rotates counterclockwise when working, so the movement direction of the external box is the same. Since the shear rubber spring connecting the screen and the box has a certain angle, the movement of the internal screen is elliptical. And due to the direction of movement, the material automatically moves to the left during the screening process, thereby determining the layout of the inlet and outlet.

[0078] The double mass has two natural frequencies. The working range of this vibrating screen is set between the two natural frequencies, so as to achieve the purpose of sub-resonance operation. The vibrator rotates one circle and the screen completes a screening movement. By changing the parameters of the driving motor, the sub-resonance movement of the vibrator, that is, the sub-resonance movement of the vibrating screen, is achieved.

[0079] Because it is a dual-mass vibrating screen, it generates two natural frequencies under external excitation. To achieve sub-resonance, the operating range of the vibrating screen is selected between the high and low order natural frequencies to achieve sub-resonance. In addition, because it is a single-unit drive, the system itself is very stable, so system stability is not a concern.

[0080] In order to further analyze the system characteristics, numerical analysis is performed.

[0081] The system parameters are set as follows: m1+m2+...+m n= 350 kg, m = 700 kg, mo = 20 kg, J = 500 kg-m 2 , k x = k y = 550 kN / m, k = 11800 kN / m, k ψ = 450 kN / rad, f x = f y = 6.27 kN-s / m, f ψ = 5.20 kN-s / rad, r = 0.15 m. According to the above parameters and the parameter determination method, the system natural frequency can be obtained: ω x = ω y = 224.89 rad / s, motor type: three-phase squirrel cage, 50Hz, 380V, 6-pole, 0.75kW, rated speed 980r / min.

Claims

1. A method for determining parameters of a single-machine driven energy-saving horizontal elliptical vibrating screen, characterized in that: The single-machine driven energy-saving horizontal elliptical vibrating screen comprises: an exciter (5), an outer mass body (2), an inner mass body (3), a shear spring (4), and a vibration isolation spring (1); the vibration isolation spring (1) is symmetrically distributed and connected to a foundation (6) and the outer mass body (2); the exciter (5) comprises an eccentric rotor and an induction motor, and is located at the mass center of the outer mass body (2); the exciter (5) rotates around the center of its own rotation axis to generate an exciting force, drive the horizontal elliptical vibrating screen system to generate vibration intensity, and drive the inner mass body (3) to achieve elliptical motion; the inner mass body comprises a plurality of masses, each of which is connected to the inner base of the outer mass body (2) via a plurality of shear springs (4); all the shear springs (4) have the same inclination angle; and adjacent masses are equidistant. The outer mass (2) is a vibrating screen body, and the inner mass (3) is a screen mesh; the shear springs (4) are distributed at both ends of the mass; the feed port and the discharge port of the vibrating screen body are symmetrically distributed with respect to the center of mass of the vibrating screen body; The parameter determination method comprises the following steps: Step 1, establish the dynamic model and system motion differential equation; Set the fixed coordinate Oxy, the rotation center of the exciter (5) is O, and its corresponding phase is expressed as The entire horizontal elliptical vibrating screen system has three degrees of freedom, which are divided into vibration in the x-direction, vibration in the y-direction and swing around the center of mass ψ; Select x, y, ψ, For generalized coordinates, based on the Lagrange equation, the motion differential equation of the horizontal elliptical vibrating screen system is derived as follows: in; M1=m1+m2+m3+…+m n ,M2=m0+m v ,M=M1+M2 β＝0°-90° l x =l1·cosβ,l y =l2·cosβ Where, M is the total mass of the horizontal elliptical vibrating screen system; m v is the mass of the external mass; m0 is the mass of the eccentric rotor of the exciter; m i is the mass of the screen, i=1,2,3…n; J is the moment of inertia of the entire horizontal elliptical vibrating screen system; J0 is the moment of inertia of the exciter; J m is the moment of inertia of the inner mass, outer mass and exciter induction motor; l e is the equivalent gyration radius of the horizontal elliptical vibrating screen system; r is the eccentricity of the exciter; f0 is the shaft damping coefficient of the induction motor; T0 is the electromagnetic output torque of the induction motor; k x , k ψ are the spring stiffness of the horizontal elliptical vibrating screen system in the x and ψ directions respectively; k, k y are the spring stiffness of the endoplasmic and ectoplasmic bodies in the y direction, respectively; f x , f ψ are the damping coefficients of the horizontal elliptical vibrating screen system in the x and ψ directions respectively; f 1y ,f 2y are the damping coefficients of the inner mass and outer mass in the y direction respectively; l1 is the straight-line distance from the connection point of the isolation spring (1) and the outer mass to the mass center of the vibrating screen; l2 is the horizontal distance from the connection point of the isolation spring (1) and the outer mass to the mass center of the vibrating screen; β is the inclination angle of the shear spring; is the first-order time derivative; is the second-order time derivative; Step 2, calculating the natural frequency, steady-state response and trajectory equation of the horizontal elliptical vibrating screen system; Step 3: Calculate the high-order natural frequency and low-order natural frequency of the horizontal elliptical vibrating screen system.

2. The method for determining parameters of a single-machine driven energy-saving horizontal elliptical vibrating screen according to claim 1, characterized in that: When the inclination angle of the shear spring (4) is 0-90 degrees, the vibrator (5) rotates counterclockwise, the feed port is located at the upper right of the vibrating screen body, and the discharge port is located at the lower left of the vibrating screen body; when the inclination angle of the shear spring (4) is 90-180 degrees, the vibrator (5) rotates clockwise, the feed port is located at the upper left of the vibrating screen body, and the discharge port is located at the lower right of the vibrating screen body.

3. The method for determining parameters of a single-machine driven energy-saving horizontal elliptical vibrating screen according to claim 1, characterized in that: The natural frequency, steady-state response and trajectory equations of the horizontal elliptical vibrating screen system are calculated as follows; In steady state, equation (2) does not take into account k x and k y are all less than k, ignoring the damping constant f of the external mass 2y ; In summary, formula (1) and formula (2) are simplified to In the formula M1′=M1, Ignore k y , so M2′=M2 Arranging equations (6) and (7), we get: Where, y3=y1-y2 Among them, M3 is the induced mass of the horizontal elliptical vibrating screen system, y3 is the relative displacement of y1 and y2; According to formula (8), the natural frequency ω of the horizontal elliptical vibrating screen system is deduced n ; Where, From the above formula, we can see that when ω m0 / ω n =1, the horizontal elliptical vibrating screen system resonates, and y 12 has a maximum value, that is, the amplitude is The absolute motion response of the horizontal elliptical vibrating screen system in the x, y and ψ directions is derived as follows by the transfer function method: When a e cj +e b e d >0 time, When a e cj +e b e d <0 time, From the above, we can see that the maximum displacement of the endoplasmic body in the x direction is The maximum displacement in the y direction is 4. The method for determining parameters of a single-machine driven energy-saving horizontal elliptical vibrating screen according to claim 3 is characterized in that: The elliptical trajectory equation of the endoplasmic body is: Where, Where x1, y1, and ψ1 are the absolute motion responses of the endoplasmic body in the x, y, and ψ directions, respectively.

5. The method for determining parameters of a single-machine driven energy-saving horizontal elliptical vibrating screen according to claim 3, characterized in that: The calculation of the high-order natural frequency and low-order natural frequency of the horizontal elliptical vibrating screen system is specifically as follows: From equations (1) and (2), the characteristic value equation of the horizontal elliptical vibrating screen system and the two corresponding high-order natural frequencies and low-order natural frequencies are expressed as (k-ω 2 M1)(k+k y -ω 2 M2)-k 2 =0 (14) The solution is In the formula b=M1(k y +k)+M2k, c=[M1(k+k y )] 2 +(M2k) 2 +2M1M2k(k-k y ) Ignore parameter k 1y After that, we get ω1=ω0; from the above formula, we can know the two frequencies of the horizontal elliptical vibrating screen system, and ω2<ω1=ω0; adjust the operating frequency of the motor to make it less than the natural frequency ω0 of the horizontal elliptical vibrating screen system to achieve sub-resonance operation of the vibrating screen.

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