Dwell-Rise-Fall-Dwell and Dwell-Fall-Rise-Dwell cam laws. Sections 9 to 13: segments having asymmetric rise and fall periods.
Abstract:ESDU 06003 provides guidance on the selection of cam laws suitable for Dwell-Rise-Fall-Dwell (DRFD) and Dwell-Fall-Rise-Dwell (DFRD) output motions having unequal rise and fall periods, including those having an intermediate constant-velocity component in either or both the rise and fall actions. The associated analysis, suitable cam laws and the definition of motions having equal rise and fall periods are given in companion ESDU 06002 and examples are provided in ESDU 06004. The equations of Dwell-Rise-Dwell (DRD) cams laws, some of which are suitable only for the component of blended profiles adjoining the dwell are given in ESDU 82006. The use of an associated computer program, described in ESDU 06005 (to be issued), is recommended for all calculations including sensitivity analyses to optimise the motion. This Item can be used to define DRFD or DFRD motions formed from either a single cam law or from blended components of suitable cam laws. The procedure used for blending motions ensures continuity of displacement, velocity and acceleration with finite jerk throughout the motion. Unlike a DRFD or DFRD motion having equal rise and fall periods, an asymmetric motion requires an additional blend to be inserted at the reversal of follower velocity. At this position both the follower velocity and jerk are zero.
|Data Item ESDU 06003