外文翻译-椭圆振动筛动力学与筛选特色随时间变化的追踪.doc

1、英文原文Dynamics and screening characteristics of vibrating screen with variable elliptical traceAbstract: The ideal motion characteristics for the vibrating screen was presented according to the principle of screening process with constant bed thickness. A new vibrating screen with variable elliptical

2、trace was proposed. An accurate mechanical model was constructed according to the required structural motion features. Applying multi-degree-of-freedom vibration theory, characteristics of the vibrating screen was analyzed. Kinematics parameters of the vibrating screen which motion traces were linea

3、r, circular or elliptical were obtained. The stable solutions of the dynamic equations gave the motions of the vibrating screen by means of computer simulations. Technological parameters, including amplitude, movement velocity and throwing index, of five specific points along the screen surface were

4、 gained by theoretical calculation. The results show that the traces of the new designed vibrating screen follow the ideal screening motion. The screening efficiency and processing capacity may thus be effectively improved.Keywords: variable elliptical trace; screening process with constant bed thic

5、kness; dynamic model; motion characteristic; screening characteristics1 IntroductionScreening operations are an important part of coal processing. The vibrating screen is one of the most extensively used screening tools. Vibrating screens, such as linear vibrating screen, circular vibrating screen o

6、r elliptical vibrating screen, have a simple translational motion. The motion follows the same path everywhere on the screen and so the screen has constant transport velocity and throwing index, which leads to low screening efficiency. Augmenting the throwing index to improve the processing capacity

7、 breaks the exciting motors or lowers the working intensity.In this paper, we report on the design of a new vibrating screen with variable motion traces that is based on the principle of screening process with constant bed thickness. Different parts of the vibrating screen traverse different ellipti

8、cal traces and the resulting motion agrees well with the ideal motion. Thus the screen processing capacity and efficiency can both be improved.2 Ideal motions for a screen surface and the proposal of a vibrating screen with variable elliptical trace2.1 Screening characteristics of common vibrating s

9、creensVibrating screens commonly work at fixed vibration intensity. Material on the screen surface moves by throwing, rolling or sliding motions. For common screeners, material granularity is widely distributed at the feed end. The energy imparted to the material particles from the vibrating screen

10、is severely dissipated. Consequently, a large number of particles become laminated only a short distance from the feed end. The material penetrates the screen within the first 1/4 to 1/2 of the screen, which affects screening and lowers processing capacity. The decrease of fine-grained material caus

11、es the ratio of particles close in size to, or larger than, the mesh to increase. Thus, the screening efficiency declines dramatically. The material granularity simultaneously becomes uniform and the energy imparted from the vibrations to the material suffers little loss .Hence, the amplitude and ve

12、locity of the material particles increase. This causes the material bed depth at the feed end to be thick while at the discharge end it is thin. This kind of motion leads to an asymmetrical penetration along the screen surface, which influences the screening efficiency and processing capability. Com

13、mon screening characteristics are shown in Fig.1.2.2 Ideal motion for screen surface and implementing schemeThe ideal motion for screen surface is described below, according to the principle of screening process with constant bed thickness. The feed end of the screen has a bigger throwing index and

14、a higher material delivery velocity, which makes bulk material quickly penetrate and causes rapid de-laminating. Earlier lamination of material increases the probability of fine-grained material passing through the mesh. The screen has an appropriate throwing index and a little higher material deliv

15、ery velocity in its middle part. This is of benefit for stabilizing fine-grained materials and for penetrating uniformly along the screen length. A lower throwing index and material delivery velocity near the discharge end causes the material to stay longer on the screen and encourages more complete

16、 penetration of the mesh.Two methods are currently used to improve screening efficiency. The first is to add material to the screen from multiple feed ports. This is troublesome in practical use especially in terms of controlling the distribution of differently granulated materials. Hence it is rarely used in practical production. The second way is to adopt new screening equipment like, for example, a constant thickness screen. The motion of the new screen surface c