Preliminary Analytical Design and Rotating-Unbalance Assessment of a Multi-Station Cam-Screw Mechanical Press

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Abstract
This study presents a preliminary analytical framework for evaluating the mass-geometric characteristics and rotating unbalance of a multi-station cam-screw mechanical press. The proposed configuration comprises two cam-screw actuators connected by a common working beam and incorporates a conceptual mechanically synchronised strip-feeding arrangement. The principal analytical contribution is a first-moment-based model for determining the centre of mass and static unbalance of an idealised asymmetric cam ridge represented by a constant-width polar volume. The model is supplemented by counterweight sizing, a numerical-geometric CAD comparison, dimensionless parametric sensitivity analysis, and an assessment of phase-dependent rotating forces and couple moments. For the nominal geometry, the calculated ridge volume is approximately 121.73 cm3, the radial centroid eccentricity is 37.41 mm, and the static unbalance is 35.75 kg·mm. The CAD-derived mass properties show small deviations from the analytical results, although both representations share the same geometric assumptions. The nominal working angular interval of 305° corresponds to an angular utilisation coefficient of 84.72%; however, this parameter does not establish an increase in production throughput. An additional fifth-order polynomial reference trajectory indicates that the maximum return acceleration for an illustrative 20 mm stroke increases from 123.68 to 343.55 m/s2 between 300 and 500 rpm. The phase analysis demonstrates that cancellation of the resultant primary rotating force does not necessarily eliminate the associated couple moment. The results provide a basis for preliminary mass-property assessment and balancing calculations, while the actual cam–follower kinematics, complete rotor balance, structural response and industrial operating performance require further validation.

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