一个展示直线振动筛筛板上单质点运动情况的仿真实验-外文文献翻译
附录
A virtual experiment showing single particle motion on a linearly vibrating screen-
deck
ZHAO Lala , LIU Chusheng, YAN Junxia
School of Mechanical and Electrical Engineering, China University of Mining &
Technology, Xuzhou 221008, China
1 Introduction
Vibration screening is a complicated process used in the mineral processing area
that is affected by the vibration and other technical parameters of the screen and by
the processed material's properties. The motion of the material on the screen deck has
a direct relation to the quality of the screening process. Factors such as the penetration
probability of the particles and the productivity of the apparatus are important. So
investigating the theory of motion and the properties of the screened materials is of
great significance for choosing reasonable kinematic parameters that ensure an
effective screening process.
The sieving experiment forms the foundation of screening theory. The traditional
experimental methods have the disadvantages of being complex to operate, being
easily influenced by outside conditions and being difficult to carry out accurately in
small scale. Virtual experimental technology, on the other hand, has the advantages of
low cost, of having no limits in the field related to the available time and number of
tests and of affording the simulation of complex processes. Virtual techniques have
been widely applied in studies within military, medical and industrial fields.
We describe a virtual screening experimental system built upon physical
simulation principles. The motion of a single particle on a linearly vibrating screen
deck was studied. The influences of kinematic parameters on the state of motion were
discussed. These results could provide a reference for the convenient study of
vibrating screen theory and sieving practice.
2 Theory of linear motion on a vibrating screen
Different kinematic parameters, such as the vibration frequency, f, the amplitude,
λ, the inclination angle of the screen plate, a0, or the direction angle of vibration, δ,
may be changed to affect the motion of material on the screen deck. A motion that is
static, positively sliding, negatively sliding or throwing can be obtained. The throwing
motion provides good segregation performance, good screening and higher sieving
efficiency and productivity. Hence, a throwing motion is adopted for most vibrating
screens.
Fig. 1 shows a kinematic model of a linear vibration screening process. The vibration
motion is sinusoidal and linear. Its displacement is given by:
(1)
where λ is the amplitude of screen motion along the vibration direction, mm； ω the
circular frequency of vibration, rad/s； t time, s； and φ the vibration phase angle, °.
Fig. 1 Kinematic model of a linear vibration screening process
We let the particle fall freely under the influence of gravity from its initial
position until it hits the vibrating screen deck. The particle will then undergo a con-
tinuous throwing motion after elastic-plastic collisions with the vibration deck. Let the
time of the i'th collision between the particle and the screen be ti and ignore the time
required for the collision process itself. Then, based on the law of conservation of en-
ergy, the particle velocity along the normal direction of the screen deck after the
collision is given by:
(2)
where δ is the direction angle of vibration, °； the y-direction velocity of the particle
before the i'th collision, m/s； the screen deck velocity at the i'th collision, m/s； and
e the elastic coefficient of restitution of the colliding particle.
Conservation of energy requires that the thrown height relative to the screen deck
after the collision is:
(3)
where g is the gravitational acceleration constant, m/s2； and a0 the inclination angle
of the screen deck, °. The theoretical average thrown height of the particle is then:
(4)
where n is the number of collisions of the particle. Because there is no collision along
the screen deck direction (the x-direction) for the particle, the theoretical average
throwing height of the particle is determined by:
(5)
where iD is the throwing coefficient； and D the throwing index.
3 Simulation and discussion
The situation for simulation of a single particle on a cylindrical-bar type linear
vibrating screen deck is shown in Fig. 2a. A global coordinate system (unit: cm) was
adopted and the center of the scene at ground level was set as the origin of the
coordinate system. The initial position of the screen and of the particle is (0, 0, 15)
and (-25, 0, 30), respectively. The screen deck area is 60 cm×30 cm, the screen ap-
erture size (a) is 2 cm, the particle diameter (d) is 4 cm and the elastic coefficient of
restitution (e) is 0.5. Fig. 2b shows the trajectory of the particle through space during
the screening process.
Taking the trajectory in the z-direction as our research object, the influence of
vibration frequency and amplitude, inclination angle of the screen deck and vibration
direction angle on the average particle velocity and average throwing height will be
discussed.
摘要：
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附录Avirtualexperimentshowingsingleparticlemotiononalinearlyvibratingscreen-deckZHAOLala,LIUChusheng,YANJunxiaSchoolofMechanicalandElectricalEngineering,ChinaUniversityofMining&Technology,Xuzhou221008,China1IntroductionVibrationscreeningisacomplicatedprocessusedinthemineralprocessingareathatisaffected...
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作者：闻远设计
分类：课程设计课件资料
价格：15光币
属性：17 页
大小：446.5KB
格式：DOC
时间：2023-11-02
