Cleveland Motion Controls ULTRA ISC CARTRIDGE TRANSDUCER REV AA - Manual (Page 27)

MAN-70430-0 R EV AA U LTRA S ERIES S TATIONARY S HAFT T RANSDUCER T ECHNICAL M ANUAL
W 1.75 1.88
Y 1/2 1/2
Z 1.50 1.70
W 44.5 47.6
Y M-12 M12
Z 38.1 43.2
*Maximum shaft mm diameter 30.00
Figure 12 – Mounting Dimensions
4.3 Pre-Installation Precautions
4.3.1 R OLL B ALANCE
The sensing roll must be adequately balanced. Understand that the balance of the sensing roll will be more
demanding than that typically needed in general rotating machinery. The goal goes beyond just limiting the
force to which bearings will be subjected, but rather to minimize the generation of an unintended noise
component in the transducer tension signal. The centrifugal force caused by imbalance can be estimated
using the following formula:
F = (1.77 x 10 -6 ) x W x R x (RPM) 2
Where:
F = centrifugal force (in units of lb-f)
W = weight imbalance (in units of ounces)
R = radius of displacement, distance of imbalance weight from roll axis of rotation (in inches)
RPM = Revolution per minute
The force increase is equal to the square of the RPM, or in other words, doubling the RPM causes four
times the imbalance force. Because rolls tend to have a high length-to-diameter ratio, two-plane (dynamic)
balancing is recommended. Balancing is particularly needed where higher RPMs and lower web forces are
involved.
To illustrate how much imbalance induced “noise” could be generated, the following table shows the force
disturbance for various ISO balance grades for an illustrative case of a 20 pound roll (4” diameter x 36”
long, aluminum ) rotating at 1500 RPM.
Balance Grade
(ISO 1940/1)
Residual Imbalance
Resultant Force due to
Residual Imbalance
G16 1.25 oz-in +/- 5 lb-f at 25 Hz
G6.3 0.5 oz-in +/- 2 lb-f at 25 Hz
G2.5 0.2 oz-in +/- 0.8 lb-f at 25 Hz
G1 0.08 oz-in +/- 0.3 lb-f at 25 Hz
4.3.2 C RITICAL R OLL S PEED
Even with a balanced roll, a vibration can be set up in a stationary shaft. If this vibration (in cycles per
minute) occurs at the harmonic frequency of the shaft, the transducers can be damaged. To determine
critical roll speed, use the following formula:
Critical roll speed in RPM = 4.8 x 10
6
x Shaft O.D.
(Shaft Length) 2
(Dimensions are in inches)
To assure that this issue is avoided, the critical roll speed should be at least 20% above the roll speed
attained at maximum web speed.
4.3.3 A VOIDING D AMAGE T O THE T RANSDUCER
To avoid damaging the transducers, refrain from repetitive overloading above the maximum working force
or severe overloading.
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