| Summary: | 碩士 === 國立成功大學 === 機械工程研究所 === 83 === The Variable pitch lead screw transmission mechanism is one of
important units in shuttleless weaving looms. It plays a major
role regarding the performance of shuttleless weaving looms. A
variable pitch lead screw transmission mechanism consists of a
slider-crank mechanism, a variable pitch lead screw, and four
meshing elements adjacent to both the slider and the screw.
The screw is driven by the power flow through the crank, the
con- necting rod, the slider, and meshing elements. The
purpose of this research is to study the effect of geometric
parameters on the kinematic and dynamic performances of
variable pitch lead screw transmission mechanisms and to obtain
optimum designs. Variable pitch lead screws are generated based
on specified meshing elements with special motion curves.
Meshing elements of ruled-revolution-surface (cylinder, cone,
and hyperboliod of one sheet) and involute-revolution-surface
(concave involute- revolution-surface and convex involute-
revolution-surface) are adopted. And, the corresponding motion
curves are modified trapezoidal curve, modified constact
velocity curve, modified sine curve, first type polynomial
curve, and second type polynomical curve. A computer program
is developed for analyzing kinematic and dynamic performances
of designed variable pitch lead screw transmission mechanisms.
Five different sets of geometric parameters are inputed into
this program to obtaine kinematic and dynamic performances.
The results are analyzed, and the effect of geometric
parameters are sumarited. In con- clusion, this work provides a
powerful tool for selecting geo- metric parameters, meshing
elements, and motion curves in designing optimum kinematic and
dynamic performances of variable pitch lead screw transmission
mechanisms for shuttleless weaving looms.
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