《机械原理》课程PPT教学课件（Theory of Machines and Mechanisms）Chap3 planar linkage

Chapter 3 planar linkage 3.1 Types of the four-bar linkages 3.2 Variation of revolute four-bar mechanism 3.3 Application of the linkages 3.4 Characteristics Analysis of four-bar linkages 3.5 Velocity analysis by the Method of instant centers 3.6 Kinematic synthesis of four-bar linkages

Chapter 3 planar linkage 3.1 Types of the four-bar linkages 3.2 Variation of revolute four-bar mechanism 3.3 Application of the linkages 3.4 Characteristics Analysis of four-bar linkages 3.5 Velocity analysis by the Method of instant centers 3.6 Kinematic synthesis of four-bar linkages

Chapter 3 planar linkage Mechanisms are used in a great variety of machines and devices.The simplest closed-loop linkage is the four-bar,which has three moving links and four pin joints

Chapter 3 planar linkage ◼ Mechanisms are used in a great variety of machines and devices. The simplest closed-loop linkage is the ◼ four-bar,which has three ◼ moving links and ◼ four pin joints. 4

3.1 Types of the four-bar linkages Types: 1)Crank-rocker mechanism 2)Double-crank mechanism 3)Double-rocker mechanism

3.1 Types of the four-bar linkages Types: 1) Crank-rocker mechanism 2) Double-crank mechanism 3) Double-rocker mechanism

B B A D Double-rocker Crank-rocker Double-crank Blender Crane

◼ Crank-rocker Double-crank Double-rocker Blender Crane

2 A 777 i加 4 凶 冲床

冲床

3.2 Variation of revolute four-bar mechanism Transformation techniques or rules that can be applied 1.Replacing a revolute pair with a sliding pair ■ 2.Taking different links as the frame 3.Enlarge a revolute pair 4.Interchanging guide-bar and sliding block

3.2 Variation of revolute four-bar mechanism ◼ Transformation techniques or rules that can be applied ◼ 1. Replacing a revolute pair with a sliding pair ◼ 2. Taking different links as the frame ◼ 3. Enlarge a revolute pair ◼ 4. Interchanging guide-bar and sliding block

1.Replacing a revolute pair with a sliding pair e:represents eccentric or offset ww77

1. Replacing a revolute pair with a sliding pair ◼ e: represents eccentric or offset

2.Taking different links as the frame For the same kinematic chain,different kinds of mechanisms will be generated by holding different links fixes as the frame.Such kinds of variations are called inversions

◼ For the same kinematic chain,different kinds of mechanisms will be generated by holding different links fixes as the frame. Such kinds of variations are called inversions. 2. Taking different links as the frame

3.Enlarge a revolute pair 3

3. Enlarge a revolute pair ◼

4.Interchanging guide-bar and sliding block

4. Interchanging guide-bar and sliding block ◼