Lenze DSD - Manual (Page 150)

7 Applications
7.13 Belt conveyor for bulk material
150
Lenze · Drive Solution Designer · Manual · DMS 4.2 EN · 12/2013 · TD23
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[7-141] Equation 4: Line load of the payload
[7-142] Equation 5: Line load of the belt
[7-143] Equation 6: Line load of the rolls
Fill level coefficient
The filling factor f is important for the value of the main resistance. The lower the gradient resist-
ance of the conveyor, the greater is the impact of this value.
The effort to always be on the safe side when carrying out the dimensioning, together with the im-
precise description of the operating characteristics and the large margin with regard to the coeffi-
cient f (see following table) could cause considerable overdimensioning.
In order to avoid this overdimensioning, a more precise determination of the coefficient f is re-
quired.
• The filling factor f is basically determined by the rolling resistance of the idlers and the indenta-
tion resistance.
• If the belt is very slack, the flexing resistance of the material to be conveyed also represents a
great part of the filling factor.
m’
L
m
L
l
------- with m
L
Q
v 3600 / s
h
⋅
---------------------------- l ⋅ = =
m’
Blt
m
Blt
l
----------- =
m’
aux
m
aux
l
------------- =
The coefficient f applies to filling degrees of the belt in the range of ϕ = 0.7 ... 1.1:
Systems that are horizontally inclined and that only slightly convey downwards (operation in motor mode)
Advantageous operating conditions
• For instance good adjustment, smooth running idlers, and a low internal friction of the
material to be conveyed, low speeds.
0.017
Conventionally designed and operated systems (according to standard) 0.020
Disadvantageous operating conditions
• For instance dusty operation, low temperatures, material to be conveyed has high inter-
nal friction, overload, high speeds.
0.023 … 0.027
In the case of extremely low temperatures and, apart from that, conventionally designed
and operated systems
0.027 … 0.035
Systems with a strong inclination to convey downwards (operation in generator mode)
• A smaller value f in this case results in a greater reliability during dimensioning.
• For operation in motor mode this is achieved by a greater value f.
0.012 … 0.016