Hiroaki Funabashi

Determination of shapes of connecting rods in slider-crank mechanisms with clearances.

About slider-crank mechanisms with clearances, a dynamic design method has been discussed to determine directly the optimum shapes of connecting rods to prevent separations and collisions between pairing elements, after showing that the separations and collisions can be predicted simply from an exciting force of a model vibratory system with a mass, spring and dashpot which is derived from equations of motion of mechanisms with clearances. The results are as follows : (1) A dynamic analysis of slider-crank mechanisms with clearances has been carried out, the results of which are coincident with experimental ones. (2) A vibratory model has been derived from the equations of motion of slider-crank mechanisms with clearances. Separations between pairing elements have been shown not to occur if the exciting force of the model is constant with respect to time. (3) In order to obtain mechanisms with good dynamic performances, the shapes of their connecting rods have been determined by Simplex method with objective functions derived from the conditions where the above exciting forces become constant. No separations of pairing elements have been confirmed to occur theoretically and experimentally in the mechanisms with the optimized connecting rods.

Dynamic characteristics of planar link mechanisms with clearances during accelerated and decelerated motions.

The dynamic characteristics of a crank-and-rocker mechanism whose crank rotates at the accelerated, uniform and decelerated motions have been theoretically and experimentally analyzed with consideration of bearing clearances. Moreover, for a crank-and-rocker mechanism obtained by a dynamic design method which makes it possible to determine directly the optimum shapes of the moving links to prevent separations and collisions between pairing elements in the case where the crank rotates at a constant-speed, the influences of bearing clearances and the non-uniform motion of the crank upon the relative motions between pairing elements and the input torque have been discussed together with experiments, comparing with the dynamic characteristics of the traditional mechanism whose shape of the coupler is a rectangle.

A kineto-elastodynamic analysis of planar link mechanisms with clearances and three-dimensional offsets.

The authors have already analyzed, both theoretically and experimentally, the kineto-elastodynamic characteristics of planar link mechanisms with three-dimensional offsets. In the present paper, a kineto-elastodynamic analysis of a crank-and -rocker mechanism with consideration of bearing clearances and three-dimensional offsets has been carried out. The effects of the magnitudes of bearing clearances and three-dimensional offsets has been carried out. The effects of the magnitudes of bearing clearances and three-dimensional offsets upon the angles of torsions and the deflections of elastic links, the joint forces and moments, the dynamic deviations of rocker angle, and the relative motions between pairing elements have been theoretically and experimentally revealed.

Dynamic characteristics of plane link mechanisms with clearances (Restraint of separation between pairing elements)

For the development of mechanical systems of high-speed and high-precision, a dynamic design theory with consideration of bearing clearances which produce a great influence upon the dynamic characteristics of the systems is strongly demanded. About a four-bar mechanism with clearances, the authors have already revealed that the separations between pairing elements can be predicted from an exciting force of a model vibratory system with a mass, spring and dashpot which is derived from equations of motion of mechanisms with clearances. In this paper, about a crank-and-rocker mechanism with clearances, three kinds of restraint methods of separations between pairing elements have been discussed with consideration of the conditions where the above exiting forces decrease or become constant. Especially, in order to obtain mechanisms with good dynamic performances, an optimum design method of the mechanisms with clearances has been discussed to determined directly shapes of moving links instead of their mass parameters.

On the Profiles of Bands in the Rolamites

In rolamites, the band-generated forces can be known when the profiles of bands are given, but it cannot be known what profiles generate the prescribed forces. Then, in order to apply the rolamite as a transducer between force and displacement, the profiles of bands have been investigated to generate the desired functions of forces in the case where the distances between guides, diameters of rollers and moduli of longitudinal elasticity of bands are known. The prescribed forces have been generally obtained by solving an inhomogeneous difference equation about the flexural rigidities of bands. The forces have been also obtained by the bands with partially constant rigidities though the maximum displacement of rollers are limited to certain values.

On the Number of Conditions in the Syntheses of Spatial Four-Bar Mechanisms

This paper aims to make the analyses and syntheses of many spatial four-bar mechanisms possible. One the spatial four-bar mechanisms with a single degree of freedom between the driver and follower links which have pairs of one or two degrees of freedom on the fixed links, the constants which determine the form and position of each mechanism are first indicated, and the relations of the constants are analysed. Then the relations are made clear between number of characteristic constants in mechanisms and the synthetic conditions, namely, number of precision points, order of differential coefficients on the displacement curves and the constants of mechanism given prior to syntheses. The conditions to connect the driver and follower links with the coupler links are analysed in relation to many combinations of pairs on the couplers. From the equations of these conditions, the displacement equations of all mechanisms may be easily obtained.