图 上海文通大￥ Dimensional synthesis Aa ILAO ToNr:UNpain Euclidean geometry(欧几里得几何) The rules for bisection of lines and angles,properties of parallel and perpendicular lines,and definitions of arcs. Compass,protractor,and rule are the only tools needed for graphical linkage synthesis 国 上久通大学 Two-Position synthesis Rocker output(pure rotation)and coupler output (complex motion) Rocker output is most suitable for situations in which a Grashof crank-rocker is desired.A case of function generation. Coupler output is more general and is a simple case of motion generation in which This solution will frequently lead to a triple-rocker. The fourbar triple-rocker can be motor driven by the addition of a dyad(twobar chain),which makes the final result a Watt's sixbar containing a Grashof fourbar subchain. 6
6 Euclidean geometry (欧几里得几何) The rules for bisection of lines and angles, properties of parallel and perpendicular lines, and definitions of arcs. Compass, protractor, and rule are the only tools needed for graphical linkage synthesis Dimensional synthesis Rocker output (pure rotation) and coupler output (complex motion) Rocker output is most suitable for situations in which a Grashof crank-rocker is desired. A case of function generation. Coupler output is more general and is a simple case of motion generation in which This solution will frequently lead to a triple-rocker. The fourbar triple-rocker can be motor driven by the addition of a dyad (twobar chain), which makes the final result a Watt's sixbar containing a Grashof fourbar subchain. Two – Position synthesis
圈上泽充大学 1.Two-Position synthesis GHA ILAO TONE:UNpin Problem:Design a fourbar Grashof crank-rocker to give 45 of rocker rotation with equal time forward and back,from a constant speed motor input. Draw O,B in two extreme Link 3 positions Draw chord B,B2 in either Link 2 direction Select point O2 Bisect B,B,and draw circle of that radius at O, Crank-O2A,Coupler AB, Rocker O2B,Ground O2O 02 64 0 Your choice 国 上久通大学 Two-Position synthesis 1.Grashoff non-quick return crank-rocker (b)Finished llnkage Link 3 Link 2 B> A 0 Link 4 Link I Link 3 7
7 1. Two – Position synthesis • Draw O4B in two extreme positions • Draw chord B1B2 in either direction • Select point O2 • Bisect B1B2 and draw circle of that radius at O2 • Crank-O2A, Coupler AB, Rocker O4B, Ground O2O4 45° Problem: Design a fourbar Grashof crank-rocker to give 45°of rocker rotation with equal time forward and back, from a constant speed motor input. 1. Grashoff non-quick return crank-rocker Two – Position synthesis