rulmeca RDR BL3, Technical Manual

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TECHNICAL MANUAL FOR THE RDR BL3 - V1.1 DRIVE ROLLER Rev. 21/09/2018 page 11
4.4 Example of choosing the Drive Roller
Weight of the conveyed material: 30 kg.
PVC package.
Conveying speed: 0.5 m/s.
Ft = 30 kg x 9.81 m/s2 x 0.04 = 11.7 N.
If you also need to know the torque required, consider the radius of the Drive Roller (equal to 25 mm = 0.025 m).
The torque (force x radius) is equal to 11.7 N x 0.025 m = 0.3 Nm.
The necessary mechanical power (W) (Tangential Force x Speed) will be 11.7 N x 0.5 m/s = 5.9 W.
Remember that the calculation does not take account of possible power absorption due to belts or transmission
systems for conveying the driven rollers (conveying differs according to the number, type and tension of connected
belts).
Use an appropriate safety coefficient to calculate oversizing.
When selecting the Drive Roller, in addition to the above data, you must also consider the type of use (intermittent
or continuous), average life required and the electronic functions required to run the system.
If you have doubts, fill in the form at the end of this manual and contact Rulli Rulmeca S.p.A. in order to check the
calculations made and that the correct Drive Roller has been chosen before you place your order.
WARNING! All the calculations described above (and the information in the catalog) assume that the tube diameter
is 50 mm. If claddings, rubberized features or liners increase tube diameter, speed increases proportionally and
torque decreases, in inverse proportion to the diameter.
Selecting the correct Drive Roller is the exclusive responsibility of the customer, unless agreed otherwise with Rulli
Rulmeca S.p.A. or its subsidiaries, which shall not be liable for any system malfunction, production loss or damage
to the conveyed items that are due to choosing the wrong type of Drive Roller.
4.5 Parameter conversions of the rotation speed of the Drive Roller
Linear speed is normally expressed in m/s. Use these formulas to convert speed from metres per minute [m/’] or
[m/min] to metres per second [m/s] and vice versa:
speed [m/sec] = [m/min] speed [m/min] = [m/s] x 60
60
Speed in terms of number of revolutions per minute or Rpm is the unit of measurement of the speed of rotation of
a body over one minute.
To convert the number of roller revolutions per minute [Rpm] into tangential linear speed in [m/s] and vice versa,
the Ø of the roller must be known (the thickness of the roller cladding could vary) and these formulas are used for
the conversion:
Known speed in m/s and roller diameter:
Speed [Rpm]
= [m/s] x 1000 x 60
Ø[mm] x 3.14
Known speed in Rpm and roller diameter
Speed [m/s]
= [Rpm] x Ø[mm] x 3.14
1000 x 60
Known speed in m/s and speed in Rpm:
Ø Roller [mm]
= [m/s] x 1000 x 60
[Rpm] x 3.14