Continuous-Path Mode, Look Ahead - G64, G645 - Siemens SINUMERIK 828D Manual

Important functions for 3- to 5-axis machining
3.7.2 Continuous-path mode, Look Ahead – G64, G645
In continuous-path mode, the path velocity at the end of the block (for the block change) is not
decelerated to a level which would permit the fulfillment of an exact stop criterion. The objective
of this mode is, in fact, to avoid rapid deceleration of the path axes at the block-change point so
that the axis velocity remains as constant as possible when the program moves to the next block.
To achieve this objective, the Look Ahead function is also activated when the continuous-path
mode is selected.
Explanation of the commands
G64
G645
(recommended)
Application of G64, G645
1
G1
G1
G1
G1
© Siemens AG All rights reserved SINUMERIK, Manual, Mold-Making with 3- to 5-Axis Simultaneous Milling
Continuous-path mode – Look Ahead where the axis only brakes
at corners
Continuous-path mode with corner smoothing and tangential
block transitions within the defined tolerances.
With G645, the smoothing movement is defined so that the
acceleration of all axes involved remains smooth (no jumps) and
the parameterized maximum deviations from the original contour
are not exceeded.
In connection with Advanced Surface, it is recommended that
you only work with G645.
The objective of continuous-path mode is to
increase the velocity and harmonize the
traversing behavior. This is implemented by
two functions.
2
Look Ahead – anticipatory velocity control
1
The control calculates several NC blocks in
G1
G1
advance and determines a modal velocity
profile. The way in which this velocity control is
calculated can be set using the functions G64,
etc.
Corner rounding
The Look Ahead function also means that the
control is able to smooth the corners that it
identifies. This means that the programmed
corner points are, therefore, not approached
exactly. Sharp corners can be rounded.
These two functions mean that the contour is
created with a uniform path velocity profile.
This results in improved cutting conditions,
increases the surface quality and reduces the
machining time.
3.7
2
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