Transferring Data From The Graph To The Cam - ABB AV3 Instruction Manual

CAM CHARACTERIZATION
CAM SHAPING METHOD
C - 6
2. Refer to Figure Transferring Data from the Graph to the
CamC-7 for the method of transferring data from the graph to the
cam. For each radial line on the cam (representing a percent piston or
valve travel), find the value of signal on the graph which corresponds
to that percent piston or valve travel. Proceed along the radial line to
the concentric arc which represents the signal pressure for the radial
lines percentage piston or valve travel. Mark the cam at that point.
0 1 2
2 0 .0
1 8 .4
1 6 .8
1 5 .2
1 3 .6
SIGN A L R A N GE
E XA M P LE : C O N T RO L LE D M E D IU M
(4-20 m A)
1 2 .0
R E Q U IR E D AT 7 .8 P S IG TO BE AT
60 % O F P IS TO N TR AV EL .
1 0 .4
8.8
7.2
5.6
4.0
0 10 2 0
Figure C-7. Transferring Data from the Graph to the Cam
Continue in this manner until all the radial lines are marked with a sig-
nal pressure point. (Example: in Figure C-7, the graph calls for a sig-
nal of 10.4 milliamps at 60 percent travel position. On the 60 percent
travel radial line of the cam, a mark is placed at concentric line 4, rep-
resenting that pressure.)
3. Draw a line through the points located in Step 2. This will be the
desired cam shape.
NOTE: If a cam shape has too steep a rise, the cam follower may
become locked. A cam with too steep a rise may be replaced with a
cam with a gentler rise if sufficient angularity is introduced into the
drive linkage of the actuator or cylinder. Optional blank cam (part
number 5400277_1) is available from ABB if alteration of the stan-
dard cam is not desired.
CA M R A D IAL LIN ES
3 4 5 6 7 8
30 40 50 60 7 0 80
% O F PIS TO N O R VALV E T RAV EL
9 10
1 0
9
8
7
6
C A M
CO N C EN TR IC
5
LIN E S
4
10 0
50
3
0
2
1
0
9 0 10 0
T 00 7 97 A