机械设计基础 南理工5.ppt

The pitch curve should be designed first. The pitch curve and the cam contour are two parallel curve. The pitch curve and the cam contour are two parallel curve. d is not a point on the cam contour. a is not a point on the cam contour, either. 5.3.2 Graphical Synthesis of Plate Cam with Translating Roller follower. The roller is always tangent to the cam contour(廓线) at all times. Roller center?reference point. 设计滚子从动件凸轮机构时， 凸轮的基圆半径是指理论轮廓 曲线的基圆半径。 画小滚子，做包络线 envelope of the family of the roller circles ——实际廓线cam contour The locus of the roller center relative to the cam is called the pitch curve理论廓线of the cam. 偏置直动滚子盘形凸轮机构设计过程 Are there any other methods to find the cam contour? 可否将理论廓线的各点向径OB减去滚子半径rr，得实际廓线??? BT is a common normal (公法线) to the pitch curve and the cam contour. 5.3.3 Analytical Synthesis of the Pitch Curce 5.3.4 Analytical Synthesis of the Cam Contour 5.3.5 Locus of Centres of Milling Cutter. example 5-1 (study after class) * Theory of Machines and Mechanisms (机械原理) Chapter1 Introduction Chapter2 Structural Analysis of Planar Mechanisms Chapter3 Kinematic Analysis of Mechanisms Chapter4 Planar Linkage Mechanisms Chapter 5 Cam Mechanisms Chapter 6 Gear Mechanisms Chapter 7 Gear Trains Chapter 8 Other Mechanisms in Common Use Chapter 9 Balancing of Machinery Chapter 10 Motion of Mechanical Systems and Its Regulation Chapter 11 Efficiency of Machine Chapter 5 Cam mechanisms 本章重点： 凸轮机构分析:包括用反转法确定从动件的运动规律和机构压力角。 凸轮机构设计：包括常用运动规律的特点及选择，盘状凸轮轮廓设计，以及凸轮机构基本尺寸的确定。 本章难点： 反转法思想的建立和应用。 5.1Characteristics and Classification of Cam Mechanisms 5.2 Follower Motion Curves 5.3 Plate Cam with Translating Roller (or knife-edge) 5.4 Plate Cam with Oscillating Roller Follower 5.5 Plate Cam with Translating Flat-faced Follower 5.1Characteristics and Classification of Cam Mechanisms Applications (Used for) transmitting complicated and precise motion dwell停歇for a short time during a cycle 凸轮机构→从动件的加