ROSTA OSCILLATING MOUNTINGS - Jens S Transmisjoner

ROSTA
Technology
3. Terminology and Calculation (Crank Shaft Driven Systems)
3.1. Terminology
Symbol Unit Term
a m/s 2 Acceleration
A mm Center distance rockers
c d N/mm Dynamic spring value (rocker)
c t N/mm Total spring value (system)
f e Hz Natural frequency (elements)
f err Hz Excitation frequency
F N Force
g 9.81m/s 2 Gravitational acceleration
K
machine acc.
grav. acc.
Oscillating machine factor
Symbol Unit Term
m kg Mass
n err min –1 Revolutions per minute
R mm Crank radius
S – Center of gravity
sw = 2 · R mm Throw (peak to peak)
v th
m/min cm/s Theoretical velocity (material)
z – Quantity (number)
W % Degree of isolation
α ° Oscillation angle
β ° Rocker angle (inclination)
3.2. Calculation
Formulas for calculating oscillating machines based on the fundamental knowledges about oscillation theories.
Total spring value (system)
Exitation frequency
c t = m · ( 2π · n err ) 2 · 0.001
60
f err = 1 c ·
t · 1000
2π
m
[N/mm]
[Hz]
Oscillating Mountings
Number of rockers for resonance operation
Oscillating machine factor (g-factor of acceleration)
Acceleration force
c t
z =
0.9 · c d
K = (2π · n err ) 2
60
·R
9810
F = K · m · g
[piece]
[–]
[N]
Required driving power (approximation)
P ≈ R · K · m · g · nerr
9550 · 1000 · 2
[kW]
The theoretical material speed of a horizontally positioned
shaker conveyor with rocker arms installed under an inclination
angle of 30° can be determined out of the left graph.
Example: eccentric radius R = 25 mm and n err = 420 min –1
is giving an acceleration of ~ 5 g and offering a theoretical
material speed of ~ 53 m/min.
It requires two-mass systems with direct mass compensation
by accelerations > 1.7 g (one-mass resonance systems with
spring accumulators = up to 2.2 g possible).
Theoretical speed v th in m/min
100
90
80
70
60
50
40
30
20
10
600 min -1
-1
540 min
-1
480 min
2g
-1
420 min
-1 360 min
300 min -1
4g
3g
6g
5g
167
150
133
117
100
83
67
50
33
16.7
Theoretical speed v th in cm/sec
Throw (peak to peak) sw in mm
Crank raduis R in mm
0
0
0
10
5
20
10
30
15
40
20
50
25
60
30
70
35
80
40
90
45
100
50
110
55
0
52