Rockwell Automation Motion Analyzer Software User Manual
Page 103
Rockwell Automation Publication MOTION-UM004B-EN-P - October 2012
103
Sizing Your System
Chapter 2
Table 60 - Cutter Knife Drive Parameters
Parameter
Description
Load
(label 1 in
Figure 82
)
Total Knife Inertia
(2)
Inertia of the knife assembly at the drive shaft.
Effective Diameter
As illustrated in the Cutter Knife Drive (Rotary Knife) diagram, this is the diameter of the circle passing through the cutting
edge.
Contact Angle (Before
BDC)
Time the material must be stationary in an accurate position.
Number of Blades/Knife
Number of blades around the circumference of the knife.
Cutting Force
Maximum force required to cut through the material. Cutting force is essentially constant while maximum torque occurs at the
first point of knife contact.
Critical Preferences
(1)
(label 2 in
Figure 82
)
Max Average Line Speed
Select this option for data entry when the maximum design speed of the constant-speed sections of the line is known. This
speed does not refer to the peak velocity of the feeder section, which is determined by Motion Analyzer software.
Min Cut length at
Max line speed
When you select the option to enter data based on Max Average Line Speed, this data is required. This is
the critical condition on which the sizing process is performed. To cut shorter lengths than this critical
length, the line speed must be reduced.
Cuts/min
Select this option for data entry when the number of cuts made by the system per minute is known.
Max Cut length at
Cuts/min
When you select the option to enter data based on Cuts/min, this data is required. This is the critical
condition on which the sizing process is performed. To cut longer lengths than this critical length, the
line speed must be reduced.
System Properties
(label 3 in
Figure 82
)
Settling Time
This is the time required for the system to achieve the required position accuracy before the cut commences. The finer the
required accuracy, the longer the settling time value. This time is typically 20 to 75 ms for an A servo system.
Cosine Compensation
This option is only required for Press Cutter Knife Drive applications. The Cosine Compensation is used to make sure that while
the press cutter knife is in contact with the material being cut, the horizontal component of the knife’s velocity matches the
material speed.
Motion Type Properties
(label 4 in
Figure 82
)
Linear
Select this option for standard linear acceleration and deceleration ramps.
S-Curve
Select this option for ‘S’ shaped acceleration and deceleration ramps that are used to produce smoother motion. You need to
enter the percent jerk value for this option.
(1) At very long cut lengths, the limiting factor, determined by the design speed of the leveler rolls and unwinder, is the maximum line speed. As cut length is reduced, the servo has to index more and more
rapidly until the peak or RMS (root mean squared) torque limit is reached. To cut shorter lengths than this critical length, the line speed must be reduced. Sizing is based on this critical length, maximum
line speed and cut time, which are typically specified.
(2) Use the
to calculate the inertia value for your application, if the value is not readily available.