凸轮机构及其设计-机械原理.PPT

the equation of the return is that: 回程时的运动方程式为: characteristic and application特点和应用场合 From the diagram we could see that the acceleration does not change abruptly when the follower runs according to the Cyclonical Motion, therefore there is neither rigid impulse nor soft impulse. This results in very good appertaining characteristics. Wear, shock, stress are depressed. So this motion curve gives a good dynamic characteristic and is especially recommended for high-speed cams. 这种运动方式可以避免在速度的突然转变,但是在始末两处加速度仍然会有突变,从而产生柔性冲击,因此这类运动规律只适用于低速或者中等速度的凸轮机构. Sinusoidal Motion (Cyclonical Motion) 正弦运动规律(摆线运动规律) when the acceleration of follower changes according to the Cyclonical Motion, the equation of the rise is that: 当推杆的加速度按正弦规律变化时，其推程时的运动方程式为: the equation of the return is that: 回程时的方程式为: characteristic and application特点和应用场合 This motion curve can avoid the sudden reverse of acceleration at the middle-point of the travel. But the acceleration will still change abruptly at the beginning and end point which could produce soft impulse. so this motion curve can be used only for low or intermediate speed cam. 由图可见，推杆作正弦加速度运动时，其加速度没有突变，因而不产生冲击。这样的优良特性使得磨损，振动，压力，噪音极为减少。因此这种运动规律具有良好的动态特性，非常适合于高速运转凸轮机构。 Combined Motion Curves 组合运动规律 The basic motion curves mentioned in the last section can be combined in many cases to improve the overall dynamic characteristic, we call it combined motion curves. Using the method, could deal with some disadvantages of the basic motion curves. 为克服单一运动规律的某些缺陷,可将几种运动规律曲线组合起来,形成所谓的组合运动规律. the choose of motion curve 推杆运动规律的选择 when choose a motion curve ,we should consider the condition of the machine ,meanwhile ,the favorable dynamic character and the convenient manufacture could also be considered. 选择推杆的运动规律首先要满足机器的工作要求，同时还应该使凸轮机构具有良好的动力特性和使所设计的凸轮便于加工，等等。 let us express some different working conditions of cam mechanism 下面仅对凸轮机构的工作条件区分几种情况作一简要的说明 1.The motion curve could not be considered strictly when the cam mechanism i