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20
Actuator
Load
Fr
Fa
Lr
R
dp
La
Chapter 2 Guidelines for sizing
2-3 Verifying loads
The FHA-C actuators comprise a precise cross roller bearing for directly supporting the load weight. To give full ability of the actuator,
verify that the maximum load weight is less than the allowable load and life and static safety coefficient of the cross roller bearing.
• Verifying procedures:
(1) Verifying the maximum load
Calculate the maximum load (Mmax, Frmax, Famax).
↓
Verify the maximum loads (Mmax, Frmax, Famax) are less than (<) allowable loads (Mc, Fr, Fa)
(2) Verifying the life of the cross roller bearing
Calculate the average radial load (Frav) and the average axial load (Faav).
↓
Calculate the radial load coefficient (X) and the axial load coefficient (Y).
↓
Calculate the life of the bearing and verify the life is allowable.
(3) Verifying the static safety coefficient
Calculate the static equivalent radial load (Po)
↓
Verify the static safety coefficient.
• Specifications of the cross roller bearing
The following table shows the specifications of the cross roller bearings built in FHA-C actuators.
Table 1: Specifications of the cross roller bearings
Model Circular Offset(R) Basic dynamic Basic static Allowable Allowable Allowable
pitch of roller load rating load rating radial load axial load torsional moment
(dp) (R) (C) (Co) (Fr) (Fa) (Mc)
mm mm N N N N N•m
FHA-17C 77 17 10800 18700 2940 9800 188
FHA-25C 96.2 18.0 18000 33300 4900 14700 370
FHA-32C 112.2 18.5 24100 44300 9500 24500 530
FHA-40C 148.8 26.5 44900 88900 14700 39200 690
• Calculating the maximum load
Calculate the maximum load (Mmax, Frmax, Famax) with the following
formula and verify that they are less than their allowances.
Mmax=Frmax(Lr+R)+Famax:La (1)
Where, the variables of the formula are:
Mmax: Maximum torsional moment in N
•m(kgf•m)
Frmax: Maximum radial load in N(kgf); See Fig.1.
Famax: Maximum axial load in N(kgf); See Fig.1.
Lr, La: Loading point in mm; See Fig.1.
R: Offset: See Fig.1 and Table 1.
Figure 1 Loads
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