Continuous Path Mode, Exact Stop and LookAhead (B1)
3.5 LookAhead
Turning, Milling, Nibbling
66
Function Manual, 11/2012, 6FC5397-1CP10-5BA0
3.5
LookAhead
Function
LookAhead is a procedure in continuous path mode (G64) that achieves velocity control with
LookAhead over several NC part program blocks beyond the current block.
Without LookAhead: If the program blocks only contain very small paths, a velocity per block
is achieved that permits deceleration of the axes at the block end point without violating
acceleration limits. This means that the programmed velocity was not actually reached
although a sufficient number of prepared blocks with virtually tangential path transitions were
available.
With the LookAhead function: It is possible to plan the acceleration and deceleration phase
with approximately tangential path transitions over several blocks in order to achieve a
higher feedrate with shorter distances. Deceleration to velocity limits is possible with
LookAhead such that violation of the acceleration and velocity limit is prevented.
1
*&RQWLQXRXVSDWKPRGHZLWK/RRN$KHDG
%ORFNSDWK
1
1
1
1
1
1
1
1
1
1
*H[DFWVWRS
1
)
3URJUDPPHGIHHGUDWH)
)HHGUDWH
Figure 3-2
Comparison of the G60 and G64 velocity behavior with short travels in the blocks
LookAhead takes plannable velocity limits into consideration such as:
●
Velocity limit in the block
●
Acceleration limit in the block
●
Velocity limit on block transition
●
Synchronization with block change at block transition
●
Exact stop at block end during termination