国上泽发大坐 Basic concepts and definitions Machine(机器)：A combination of resistant bodies arranged to compel the mechanical forces of nature to do work accompanied by determinate motions. Machine(机器)：is a collection of mechanisms arranged to transmit forces and do work.(Reuleaux >Crank:a link which makes a complete revolution and is pivoted to ground, >Rocker:a link which has oscillatory (back andforth)rotation and is pivoted to ground >Coupler:a link which has complex motion and is not pivoted to ground. 圈上泽夫通大学 Basic concepts and definitions Take-up mechanism 挑线机构 Needle mechanism 刺布机构 12 10 8 SKId: 1 6
6 Machine（机器）: A combination of resistant bodies arranged to compel the mechanical forces of nature to do work accompanied by determinate motions. Machine（机器）: is a collection of mechanisms arranged to transmit forces and do work.（Reuleaux ） Crank：a link which makes a complete revolution and is pivoted to ground, Rocker：a link which has oscillatory (back andforth) rotation and is pivoted to ground Coupler ：a link which has complex motion and is not pivoted to ground. Basic concepts and definitions 8 5 6 7 8 9 10 12 11 12 10 P 1 4 2 3 1 2 3 Basic concepts and definitions Take-up mechanism 挑线机构 Needle mechanism 刺布机构
图上涤支大峰 OUTLINE Basic concepts and definitions How does a MECHANISM work? The kinematic diagram A simple equation-Gruebler Criterion Exceptions to Gruebler's Equation 国 上海充廷大学 How does A MECHANISM work Lower Pairs square X-section Revolute (R)joint-1 DOF Prismatic (P)joint-1 DOF Helical (H)joint-1 DOF 较链副 移动副△9 螺旋副 Ay C-do Cylindrie (C)joint-2 DOF Spherical (S)joint-3 DOF Planar(F月oint-3DOF 柱销制 球较副 平面副 FIGURE 2-3 (a)The six lower pairs Prismatic Revolute Cylindric Spherical Helical Planar(F) DOF 7
7 OUTLINE Basic concepts and definitions How does a MECHANISM work? The kinematic diagram A simple equation-Gruebler Criterion Exceptions to Gruebler’s Equation Prismatic Revolute Cylindric Spherical Helical Planar (F) DOF 1 1 2 3 1 3 Lower Pairs How does A MECHANISM work 铰链副 移动副 螺旋副 柱销副 球铰副 平面副
圈上泽支大峰 How does A MECHANISM work Higher Pairs-1 Names Degree of Typical form Comments freedom Roller rotates about this line at this Cylindrical instant in its motion.Roller does not slip on the surface on which it roller rolls. Cam rolls and slides on follower. Cam pair 2 01 Spur gears,helical gears,and other gears.(rolls slides) Gear pair 圆上海夫通大学 How does A MECHANISM work Higher Pairs-2 Names Typical form Degree of Comments freedom Ball rolls without slipping. Rolling ball Ball can rotate about any axis Ball in throughitscenterand slides along cylinder axis. cylinder Body can rotate about any axis through the contact point and slide Spatial point in any direction in the tangent contact plane. 8
8 Higher Pairs-1 How does A MECHANISM work Higher Pairs-2 How does A MECHANISM work
圈上泽文通大华 Planar VS Spatial Close VS Open In a planar mechanism,all of the A spherical mechanism is a relative motions of the rigid bodies are mechanical system in which the bodies in one plane or in parallel planes. move in a way that the trajectories of The rotational axes of hinged joints points in the system lie on concentric that connect the bodies in the system spheres. are perpendicular to this ground plane. The rotational axes of hinged joints that connect the bodies in the system pass through the center of these spheres. 圈上泽夫通大学 Planar VS Spatial Close VS Open If every link in the chain is connected to two or more links then the chain form one or more closed loops. If NOT,the chain is said to be open. 9
9 Planar VS Spatial Close VS Open In a planar mechanism, all of the relative motions of the rigid bodies are in one plane or in parallel planes. The rotational axes of hinged joints that connect the bodies in the system are perpendicular to this ground plane. A spherical mechanism is a mechanical system in which the bodies move in a way that the trajectories of points in the system lie on concentric spheres. The rotational axes of hinged joints that connect the bodies in the system pass through the center of these spheres. Planar VS Spatial Close VS Open If every link in the chain is connected to two or more links then the chain form one or more closed loops. If NOT, the chain is said to be open