凸轮机构讲义3.ppt

Chapter 4. Cams and Chapter 4. Cams and Its Design Its Design Sun Zhihong Sun Zhihong ******@dhu. ******@dhu. 67792580 67792580 Today Today ’’ s topics s topics ? Characteristics of cam mechanisms 凸轮机构的特点? Classification and application of cam mechanisms 凸轮机构的分类及应用? The follower ’ s motion type 从动件的运动形式 What is a cam mechanism? ? A system/mechanism that uses a cam( 凸轮) and a follower( 从动件) to create a specific motion. ? In most cases, the cam is merely a flat piece of metal that has an unusual shape or profile( 轮廓). ? The cam is attached to a shaft( 轴) which enable it to be turned by applying a turning action to the shaft. ? As the cam rotates, it is the profile or shape of the cam that causes the follower to move in a particular way. ? The movement of the follower is then transmitted( 传递) to another mechanism or another part of the mechanism. Advantages of cam mechanisms ? Simple pact( 简单、紧凑) – there only three links, cam( 凸轮), follower ( 从动件), frame( 机架). Sometimes, there is a roller( 滚子). ? The follower can precisely realize any type motion. Example Disadvantages of cam mechanisms ? Higher pair( 高副), line contact or point contact( 线或点接触) ? Can ’ t transfer( 传递) large power. Function ? Continuous turning motion → translating( 往复移动) or oscillating( 摆动) motion. Example Application of cam mechanism ? Camshaft (凸轮轴) of an Engine incorporating a Rocker Arm (摆臂) : The diagram shown right is a typical cam and follower system that could be used in an engine. This system incorporates a rocker arm. In this case the motion that the cam imparts on the follower is translated to the valve through a push rod and the rocker arm. Dobby 多臂提花机作者:潘存云教授绕线机构 3 作者:潘存云教授 1 2A yarn 线 Yarn winding machine( 绕线机) 作者:潘存云教授 13 2送料机构 Feeding mechanism 送料机构 Feeder of Automatic Machine Tools 自动机床的进刀机构??园柱凸轮回转园柱凸轮回转→→滚子带动推杆往复摆动滚子带动推杆往复摆动→→刀架的进刀和退刀刀架的进刀和退刀 1 2 刀架 o机床进给机构 1 3 24 5 放音键卷带轮皮带轮摩擦轮录音机卷带机构 3皮带轮 5 卷带轮录音机卷带机构 1放音键 2摩擦轮 4 录音机卷带机构