上海文通大粤 Cam Terminology (review) SHANGHAI JIAO TONG UNIVERSITY Type of follower motion (rotation,translation) Type of joint closure(force,form) Type of follower (roller,mushroom,flat) Direction of follower motion (radial,axial)
Cam Terminology (review) Type of follower motion (rotation, translation) Type of joint closure (force form) Type of joint closure (force, form) Typ ( , , ) e of follower (roller, mushroom, flat ) Direction of follower motion (radial, axial) ME357 Design & Manufacturing II
上游充通大学 Type of Motion Constraints SHANGHAI JLAO TONG UNIVERSITY Critical Extreme Position(CEP)-start and end positions are specified but not the path between Does not specify any constraint on path between extreme positions Critical Path Motion(CPM)-path or derivative is defined over all or part of the cam Motion Motion Accelerate mm or in Decelerate High Constant velocity Return dwell 2 3 Low dwell Rise Fall 5in 10 in/s 0 90 180 270 360 Cam angle 0 d 030 210740 360 cam angla A deg 0 0.25 0.50 0.75 1.0 Time t 00.08 0.580.67 1.00 女ne t sec ME357 Design Manufacturing Il
Type of Motion Constraints Critical Extreme Position (CEP) – start and end positions are specified but not the path between Does not specify any constraint on path Does not specify any constraint on path between extreme positions Critical Path Motion (CPM) – path or derivative is defined over all or part of the cam defined over all or part of the cam ME357 Design & Manufacturing II
上游文通大学 Type of Motion Program SHANGHAI JIAO TONG UNIVERSITY 运动规律 From the CEP cam profile Dwell -period with no output motion with input motion. 国 Rise-Fall(RF)-no dwell (think about using a crank- rocker）(RF升程-回程) Rise-Fall-Dwell(RFD)-one dwell(RFD升程-回程-休) o p Rise-Dwell-Fall-Dwell (RDFD) two dwells Coke bottling example: ME:
Type of Motion Program 运动规律 From the CEP cam profile D ll we – peri d ith t t ti ith i t io d with no ou tpu t motion with inpu t motion. Rise-Fall (RF) – no dwell (think about using a crankrock ) er ) (RF升程－回程 ) Rise-F all-Dw e( ) ll (RFD ) – o ed e n e d w ell (RFD升程 －回程 －休止 ) Rise-Dwell-Fall-Dwell (RDFD) – two dwells Coke bottlin g exam ple: ME357 Design & Manufacturing II g p
上游充通大学 Type of Motion Program SHANGHAI JIAO TONG UNIVERSITY 运动规律 .Example follower displacement profile .Obtained by linearizing cam-unwrapping it from its circular shape C=Developed Prime Circle Rise Dwell Return 十Dwell-+ +d 夏莲 b Transition or Inflection Points- a C 0 2 3 5 6 7 8 10 11 0 Station Point Numbers •Abscissa(横坐标)can be >Time >Shaft angle
Type of Motion Program 运动规律 •Example follower displacement profile •Obtained by linearizing cam – unwrapping it from its circular shape circular shape •Abscissa(横坐标) can be ¾Time ¾Shaft angle
上游究通大粤 SVAJ Diagrams SHANGHAI JLAO TONG UNIVERSITY Unwrapping the cam Plot of position(s/S), velocity(v/), acceleration(a/A)and jerk(j/J)verses cam angle 国 Basis for cam design 90 180 270 360
SVAJ Diagrams Unwrapping the cam Unwrapping the cam Plot of p ( ), osition(s/S), velocity(v/V), acceleration(a/A) and acceleration(a/A) and jerk(j/J) verses cam angle Basis for cam design Basis for cam design ME357 Design & Manufacturing II