Smooth Approach And Departure - HEIDENHAIN TNC 370 User Manual

5 Programming Tool Movements
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5.2
Contour Approach and Departure
Smooth approach and departure
With the RND function the tool approaches and departs the workpiece at
a tangent. This prevents dwell marks on the workpiece surface.
Starting and end position
The starting @ and end @ positions of machining lie outside of the
workpiece and near the first and last contour elements, respectively.
The tool paths to the starting and end positions are programmed without
radius compensation.
Input
The RND function is entered at the following locations in the program:
l
During contour approach: after the block in which the first contour point
is programmed, i.e. after the first RL/RR radius-compensated
block.
l
During contour departure: after the block in which the last contour point
is programmed, i.e. after the last RYRR radius-compensated
block.
Fig. 5.10: Smooth approach onto a contour
Fig. 5.11: Smooth departure from a contour
Program example
L
X
Y RO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .._.__._..... Starting position
@
L X __. Y RL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . First contour point @
RND R . . . . . . . . . . . . . . . . . .._................................................ Smooth approach
Contour elements
L X ... Y ... RL ........................................................ Last contour point @
RND R ....................................................................... Smooth departure
L X ... Y ... RO ........................................................ End position @
For proper
execution of an RND function, a radius must be chosen such that the arc can connect the start or end
point with the contour points.
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