THE REGIONS OF EXISTENCE OF DOUBLE-CRANK DWELL LINKAGE MECHANISMS FOR THE FOUR INFINITESIMALLY CLOSE POSITIONS OF THE COUPLER PLANE
Kharzhevskyi Viacheslav, Khmelnytskiy National University, Khmelnytskiy, Ukraine
Urgency of the research. In different fields of modern machinery it is often required to create the mechanisms with periodic dwell of the output link. For that purpose, cam mechanisms are frequently used, but linkage mechanisms are more suitable in many cases due to the absence of the higher kinematic pair and provide higher working velocities, load-carrying ability, durability and reliability. That’s why the development of the synthesis methods of linkage mechanisms is an important task.
Target setting. The problem is to carry out the kinematic synthesis of dwell linkage mechanisms at the given duration of the dwell taking into account a number of additional parameters which are practically important for the design engineer.
Actual scientific researches and issues analysis. There are two main branches in the synthesis of basic path generating mechanisms and dwell mechanisms which are composed on their basis: the usage of Chebyshev’s best approximation conditions and kinematic geometry methods, in particular – kinematic geometry of infinitesimally close positions of coupler plane by means of multiple knots of interpolation. Up-to-date synthesis of mechanisms is carried out by means of combined analytical and numerical methods.
Uninvestigatigated parts of general matters defining. The synthesis task that is not solved is multicriterion synthesis of double-crank dwell mechanisms which are composed using Ball’s points.
The research objective. The goal of the article is to carry out the optimal kinematic synthesis of the double-crank mechanisms at the given duration of the dwell, which are synthesized using Ball’s points by means of defining the regions of their geometric parameters’ existence.
The statement of basic materials. The Ball’s points in the mechanism’s coupler plane are defined for the given position of the mechanism and sizes of the links as an intersection of the inflexion circle with the curve of the cubic of stationary curvature. Using of the found Ball’s point it is possible to design of the straight-line linkage mechanism and dwell mechanism of its basis. But the inverse task that was solved in the issue is so important – to define such parameters of the mechanisms, which provide the given dwell duration of the output link.
Conclusions. The regions of existence of double-crank dwell linkage mechanisms that are synthesized using Ball’s points are suggested in the article. The usage the given reference diagrams enables to carry out the synthesis by the given duration and exactitude of the dwell, by the length of the straight-line part, by maximum displacement and other parameters.
linkage mechanisms, synthesis, straight-line mechanisms, kinematic geometry, Ball’s point
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