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Using the following formulas, you can determine how much vibration will be sufficient. Remember, the goal is to provide just enough vibration to do the job. Excessive vibration can cause excessive wear on surrounding systems.
1. LINEAR MOTION (CONTRA-ROTATING TWIN VIBRATORS)
Vibrators with their axes in the same plane and wired to contra-rotate will produce a linear motion at right angles to the vibrator axes. Amplitudes are given by the formulas below.
2. CIRCULAR MOTION (SINGLE VIBRATOR)
True circular motion is only obtained when the center of the vibrator coincides with the center of gravity of the structure. When vibrators are fixed in noncenter of gravity positions, the motion will be in the form of an ellipse which varies at different points on the structure. Amplitudes given by the formulas below are an average value suitable as an approximation.
Notations
App = Amplitude peak to peak in inches
CF = Total Centrifugal Force (pounds)
CPM = Frequency of Vibration in cycles per minute
LOAD = Total weight of structure, vibrator(s), and any loading (pounds)
R = perpendicular distance from axis of rotation to center of mass, or for practical use, to center of gravity of revolving body
v = velocity at radius R on body in feet per second
g = acceleration due to gravity = 32.16 feet per second
n = number of revolutions per minute
Please select a formula from these choices:
Amplitude
Centrifugal Force Required
Power Requirements
Vibrator Isolation
Working Moment v. Amplitude
Amplitude
Centrifugal Force Required
Power Requirements
Vibrator Isolation
Working Moment v. Amplitude
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If the frequency of vibration, load and amplitude required are known, the centrifugal force required can be calculated from the following:
Amplitude
Centrifugal Force Required
Power Requirements
Vibrator Isolation
Working Moment v. Amplitude
Top
The power required from a vibrator depends on the nature of the application and the degree of damping present. It can be shown that for any application there is a peak power requirement when damping is at an optimum level. The power required then is:
In most applications the power required can be taken as one-fifth of the above values since damping rarely reaches an excessive level. If the vibrator current is found to be too high, the out-of-balance weights should be set back until it reaches an acceptable figure.
Amplitude
Centrifugal Force Required
Power Requirements
Vibrator Isolation
Working Moment v. Amplitude
Top
When mounting vibratory equipment it is necessary to allow freedom of movement while preventing damaging vibrations from being transmitted to surrounding equipment or structural members. Generally, 95% isolation is satisfactory and will be obtained using resilient mountings having the following static deflections under the weight of the structure, load and vibrators(s):
Amplitude
Centrifugal Force Required
Power Requirements
Vibrator Isolation
Working Moment v. Amplitude
Top
The "working moment" is value equal to the vibration amplitude multiplied by the total load. When selected from the manufacturer's table it can be used to calculate either the resultant amplitude for given load (1) or the maximum load for a given amplitude (2).
Give either of these conditions the working moment can be directly substituted in the formulae for calculating centrifugal force required.
Amplitude
Centrifugal Force Required
Power Requirements
Vibrator Isolation
Working Moment v. Amplitude
Top
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DECA Vibrator
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10140 Virginia
Chicago Ridge, IL 60415
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