P R O G R A M M I N G E X A M P L E S
Programming Examples
119
CONTINUOUS CUTTING
A moving sheet of plastic must be cut with a water jet along
the pattern shown at right. The process is continuous and the
web does not stop.
Components Selected
DMC-1030: Controller
ICM-1100: Interface module
WSDK: Servo design software
Brushless motors and external amplifiers
Operation
The unique feature of this system is that the plastic sheet
moves continuously and independently at a variable speed.
As a result, the motion of the X motor must equal the sum
of two parts: motion 1 to follow the cutting pattern, and
motion 2 to follow the moving web. This can be accom-
plished easily with the DMC-1030 by separating the two
moves. Part 2 is done by electronic gearing and part 1 is
done by coordinated motion. The web motion is monitored
by an independent encoder whose output is applied to the Z
axis. Assuming that the resolution of all 3 encoders are the
same, the X motor is then required to follow Z at a ratio of 1
to accomplish part 1 of the motion. The cutting cycle is
shown above.
The motion starts at the point A with the waterjet
turned off (output bit 1 = 0). It moves toward point B,
where the waterjet is turned on, and continues to C, D, E,
F, and back to B which becomes the starting point of the
next cycle.
In order to keep the waterjet location over the correct
position, we must synchronize the cutting speed with the
web speed. Note that the length of one cutting cycle, includ-
ing the path from A to all the points, equals 20,680 counts.
At the same time, the web advances 2400 counts. This
implies that the vector speed, VS, must be equal to 8.616
times the speed of Y. This method, however, is not precise
and will create some errors that can cause position drift of X.
To eliminate this possibility, we define the starting point of
the first cycle as X = 0. Later, we check the position of X at
the start of all following cycles. If the starting position of X is
positive, the cutting speed is slow and the speed is increased
by a correction factor E.
Instruction
Interpretation
#WTRJET
Label
DP0
Define starting X position
GAZ
Set Z as master
GR1
X follows Z at 1:1
VMXY
Vector mode XY plane
#LOOP
E = _TPX/2400
Drift correction factor
SPEED = _TVZ *(1+E)
Master speed
VS SPEED*8.616
Command vector speed
VP -2400,0
Motion AB
CR 1000,270,-90
Motion BC
VP -3400,7000
Motion CD
CR 1000,180,-180
Motion DE
VP -1400,1000
Motion EF
CR 1000,0,-90
Motion F to end
VE
End of motion
BGS
Start move
AV 2400
Wait for point B
SB1
Turn waterjet on
AMS
Wait for end of cycle
CB1
Turn waterjet off
JP #LOOP
Repeat the cycle
EN
End program
Continous Cutting of
Moving Webs by Waterjet
Y
WEB
MOTION
X
E
(-1400,7000)
D
(-3400,7000)
C
(-3400,1000)
F
(-1400,1000)
A (0,0)
B (-2400,0)
Continuous Cutting Example
Cutting Cycle
