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Title: Partial cancellation of shaking force harmonics by cam modification
Authors: Chiou, Shen-Tarng
Davies, T.H.
Keywords: Balancing
Cam
Harmonic
Mechanism
Optimization
Issue Date: 1997
Publisher: © IMechE / Professional Engineering Publishing
Citation: CHIOU, S.-T. and DAVIES, T.H., 1997. Partial cancellation of shaking force harmonics by cam modification. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 211(4), pp. 253-263
Abstract: An optimization procedure for minimizing the shaking force harmonics of machinery is described. Because of constraints imposed by the specification, optimization is unlikely to make any significant reduction in the fundamental, machine frequency, term of the shaking force. That term, normally the largest, must be substantially reduced by other means for the procedure described here to be cost effective. Earlier work describing methods of reducing the fundamental term are cited. An extrusion press machine incorporating two planar mechanisms, one crank driven and one cam driven, provides an example. Two designs of the cam-driven mechanism, referred to here as cams 1 and 2, are in use in installed extrusion press machines. Harmonic analysis of the shaking force as a function of time shows that cam 2 produces smaller amplitudes of shaking force harmonics. The ten variables used in the optimization process are the amplitudes and angles of the first five terms of a trigonometric series defining the acceleration of a reciprocating mass driven by a hypothetical third cam, cam 3, which is similar to cam 2 but stripped of all harmonics of order higher than the fifth. The objective function is the sum of the amplitudes of the horizontal components of the second to fifth shaking force harmonics on the machine as a consequence of accelerations of the moving parts of both mechanisms. Several equality and inequality constraints must be met. For the extrusion press machine the result is a reduction in the amplitudes that would be created if cam 3 were to be used by approximately 10, 75, 65 and 100 per cent respectively. The improvement over cam 1 is greater. The procedure is particularly suited as a retrofit measure where the number of installed machines is large in relation to the future rate of production of new machines: a cam that has been removed from one machine can be re-cut for use on another machine.
Description: This article has been published in the journal, Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science [© PEP]. The definitive version is available at: http://dx.doi.org/10.1243/0954406971522024
Version: Published
DOI: 10.1243/0954406971522024
URI: https://dspace.lboro.ac.uk/2134/4564
ISSN: 0954-4062
Appears in Collections:Published Articles (Mechanical and Manufacturing Engineering)

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