物料在圆筒旋振筛内的筛分受力情况
112 转速公式推导
根据达朗伯原理,作用于粮粒上的重力P、法向压力N及最大静摩擦力Fmax与其离心力G组成一汇交平衡力系,取径向坐标轴x和切向坐标轴y如图2,其平衡式为:
rX=0 N-G-PcosA=0(1)
rY=0 Fmax-PsinA=0(2)
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Screen rotation in the development process of grain double cylinder, cylinder rotating sievefound field use, its speed is usually low, affecting the comprehensive effect of yield andscreening rate. Screening mechanism, the cylindrical rotating sieve sieve grain in force, the state of motion in the cylinder of the more in-depth analysis, the derivation and application principle of rotary screen speed formula is discussed, combined with the practical field investigation, design of the cylinder screen are respectively improved speed, achieved goodsieving effect the. 1 the grain in the screen cylinder by cylinder speed formula derivation ofstress analysis and the 111 grains in the screen cylinder force analysis of the influence offirst omitted the various complicated factors, to simplify the problem, taking continuous into the sieve tube inside a grain of rice grain in the stream of particles as independent study. The grain in the inner wall of the roller stress conditions are as follows: the vertical downwardgravity P, the inner wall of the drum of the normal force, tangential frictional force of F N. The cylinder rotates under the action of friction, in F, the grain with the drum rotation to startrunning, a corner after A, rice will decline relative motion and the drum. The grain is brought up the relevant height and the rotation speed of the roller. In the grain with the cylindertogether with the angular velocity X rotation in the process of rising, falling force and friction force of gravity (two P force balance force) is increasing, but the decline is always less thanthe maximum static friction force is Fmax, so the grain will not fall. When the grain is rotated to a certain height of the angle is A, the friction force and sliding force size is equal to themaximum static friction force, at this time the grain in the tangential direction in a sliding balance state, that is the point of the sliding balance. When the drum around the equilibrium point, the sliding force is greater than the maximum static friction force of Fmax, the balance is destroyed, the grain will decline. The stress state of sliding equilibrium grain, as shown in figure 1. Because the sliding friction resistance is very small, the grain will always slip into thebottom of the drum, and then once again by the sieve tube with increased, reaching a certain height to decline again, and in the fall at the same time, the grain will also move forward(sieve tube to promote the conical or inner screw). So the cycle, for the process of cleaning up screening. In fact, screening cleaning process is mainly the process of decline in the grain,thus increasing the grain down section length, i.e. increasing angle of A will improve the screening effect of the rolling sieve. It should be noted that in the sliding balance point, themaximum static friction Fmax is a variable that is not a fixed value, it is related to the angle Aand angle velocity X. Figure 1
112 speed formula derivation
According to the D'Alembert principle, method of gravity P, acting on the grain to the pressure of N and the maximum static friction force and the centrifugal force to form a Fmax Gconcurrent force system in equilibrium, taking the radial coordinate axis X and tangential axis y as shown in Figure 2, the balance type for:
RX=0 N-G-PcosA=0 (1)
RY=0 Fmax-PsinA=0 (2)
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本文关键词:圆筒旋转筛 转速 最大静摩擦力 滑动平衡 临界转速