Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 555)

Surface Grinding Fixed Cycles
Chapter 16
16-5
Certain commands or commanded motions depend on reciprocation and
are delayed until the reciprocating axis reaches the secondary reversal
point. Examples of such commands include:
coordinate changes requested for the reciprocating axis
certain fixed cycle operations as described in this chapter
a G80 is executed to cancel reciprocation
an M99 is executed at the end of a main program
If an incremental plunge or crossover is to be made (G82, G83 or G84), it
begins as the reciprocating axis decelerates to a reversal point. If a
continuous crossover is to begin (G85 or G86), it starts immediately
regardless of the location of the reciprocating axis.
Programming an incremental or absolute move to the reciprocating axis in
any program block while reciprocation is active, can change the
coordinates of the primary and secondary reversal points. In the case of
programming moves to the reciprocating axis while in incremental mode,
the incremental change is made relative to the secondary reversal point, as
illustrated in this example:
Program Block Prim. Rev. Point Sec. Rev. Point Comments
G90G80F100X10.0; none none no reciproca-
tion
G81G91X5.0I-10.0E100; X axis, 15.0 X axis, 5.0 from start
point of X = 10
X5.0I-8.0; X axis, 10.0 X axis, 2.0 from sec. rev.
point of X = 5
X-20.0I5.0; X axis, -18.0 X axis, -13.0 from sec. rev.
point of X = 2
The preceding example applies not only to the G81 shown, but to the
reciprocating axis in any grinding fixed cycles.
If already active, reciprocation motion does not stop or pause when a
grinding cycle block or a block changing the reciprocation reversal points
is executed. Instead, changes to the reciprocation motion take place at the
secondary reversal point.
A plane change (G17, G18, G19) can be requested while the reciprocation
axis is in motion. If the next grinding cycle block to be executed after the
plane change requires a different reciprocation axis, then there must be
valid reciprocation axis data included with that grinding cycle block. If
not, the error message “RECIPROCATION AXIS IN WRONG PLANE”
appears and block execution stops. Reciprocation does not stop.