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Selection Example: Stiffness Based Dimensioning
Resonance Frequency (Gear Output)
The formula
Equation 34.1
1
K
f
=
[Hz]
1
2�
J
n
fn = Resonance frequency [Hz]
K1 = Gear torsional stiffness [Nm/rad]
J = Load moment of inertia [kgm
allows the calculation of the resonance frequency at the gear output, from the given the torsional stiffness K
Drive® Gear and the load's moment of inertia. The calculated frequency should correspond with the value provided in table
33.1. The higher the load's moment of inertia, the higher is the influence of the type of application on the gear selection. If
the moment of inertia = 0, the selected application has no numerical influence on the selection result.
Resonance Speed (Gear Input)
The resonance speed n
on the input side (motor side) can be calculated using the formula
n
n
= f
· 30 [rpm]
n
n
During operation, we recommend passing the resonance speed quickly. This can be achieved by selecting a suitable gear ratio.
Another possibility the selection of a suitable gear stiffness such that the resonance speed lies beyond the required speed range.
Selection Example
HFUC-40-120-2A-GR preselected from "Selection Procedure" on page 31.
Intended application: milling head for woodworking
Moment of inertia at the gear output: 7 kgm
Resonance frequency using the preselected gear
HFUC-40-120-2A-GR:
1
f
=
n
2�
According to stiffness based dimensioning, this gear size is too small for the application.
The larger gear HFUC-50-120-2A-GR results in a resonance frequency of:
1
f
=
2�
n
Based on stiffness based dimensioning, the gear HFUC-50-120-2A-GR is recommended.
The calculated resonance speed at the input (motor) is:
n
= 30 · 30 = 900 [rpm]
n
Either, this speed should be passed quickly during acceleration and deceleration or it should
lie beyond the utilised speed range.
34
]
2
. Recommended resonance frequency from table 33.1: ≥ 30 Hz.
2
1.3
10
.
.
5
= 22 [Hz]
7
2.5
10
.
.
5
= 30 [Hz]
7
of the Harmonic
1
1021387
12/2018
V02
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