Blending - Siemens SINUMERIK 828D Function Manual

B1: Continuous­path Mode, Exact Stop, LookAhead
3.3 Continuous-path mode
3.3.3

Blending

Function
Rounding means that an angular block transition is changed to a tangential block transition by a local change to
the programmed contour. This gives the area in the vicinity of the original angular block transition (including
transitions between intermediate blocks inserted by the CNC) a continuous contour.
During rounding, it is not only the geometry axes that are taken into account, but all machine axes which traverse
synchronously. The rounding function therefore smoothes the traversing path of orientation axes as well as
general velocity step changes in synchronized axes.
Note
Rounding cannot and should not replace the functions for defined smoothing, i.e. RND,
RNDM, ASPLINE, BSPLINE, CSPLINE.
If a rounding movement initiated by G641, G642, G643, G644 or G645 is interrupted, the
corner point of the original contour will be used for subsequent repositioning, rather than the
interruption point.
Synchronization
Rounding involves shortening discontinuously adjoining blocks and inserting one or two intermediate blocks at
this point. The original block boundary is removed and can no longer be used for synchronization conditions (e.g.
auxiliary function output parallel to motion, stop at end of block).
With rounding, all synchronization conditions are best referred to the end of the shortened first block and not to
the end of the intermediate rounding block. The following block is thus not started and with a stop at end of block,
the contour of the following block can still be changed.
Design
Rounding is only performed if the block transition is to be traveled with finite velocity. The maximum path speed is
influenced by the curvature. The maximum acceleration values of the axes are not exceeded. A block without
traverse information for the path axes requires velocity "zero" and therefore no rounding.
Rounding is also used if the traversal of the block transition requires a velocity that lies below the permissible
velocity at the end of the block according to G64 (see overload factor).
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Function Manual, 09/2011, 6FC5397-0BP40-2BA0
Basic Functions