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If at least one link enters into more than two KP, such kinematic chain is
called complex KC.
All kinematic chains are divided into closed and open-ended KP.
If each link of a kinematic chain enters at least into two KP, such
kinematic chain is called a closed KC (Fig. II.18c).
If at least one link in a kinematic chain enters only into one KP, such
chain is called an open-ended KC (or open) (Fig. II.18a,b).
Kinematic chains can be either flat or spatial (three-dimensional).
Besides that kinematic chains can be definite and indefinite.
If in a kinematic chain, at a given movement one or several links are
named driver(s), other links (except for the rack) are named driven link(s),
and they receive quite certain movement, such a kinematic chain is called a
definite KC.
Now it is possible to give another definition to the notion "mechanism".
Mechanism is a kinematic chain, in which at the given movement of one
or several links all the others perform the single-valued movements.
To study the movement of any mechanism, it is not enough to know its
structure, i.e. number of links, number and classes of kinematic pairs, it is
also necessary to know the sizes of separate links influencing movement,
their mutual disposition etc (Fig. II.19.).
Therefore, studying the movement of a mechanism’ links, one usually
makes a kinematic scheme, which represents its kinematic model. Kinematic
1
2
3
4
5
6
a
b c
Fig. II.18. Examples of kinematic chains:
a - complex KC; b - open KC; c - closed KC.
1
2
2
3
3
a) b)
Fig. II.19. Different configurations of mechanisms having equal links
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