Axial Rigidity Rax

Axial Rigidity

1Rax = 1Rnu + LsRs · k
k = 1: Fixed bearing one side
k = 4: Fixed bearing both sides
Rnu = Nut rigidity on nut flange
Rs = Spindle rod rigidity per m, see table below
Ls = Loaded length of spindle [m]

Approximate Values for Rigidity of Nuts and Spindle Rod Rigidity per m

Approximate values for rigidity of nuts and spindle rod rigidity per m

Parameter d0 [mm]
25 32 40 50 63 80 100 125
Rnu* [kN/µm] 0.5 0.7 1.0 1.5 2.1 2.5 2.8 3.1
Rs [kN/µm] 0.09 0.15 0.22 0.36 0.6 0.9 1.5 2.4

*) Values for preloaded double nut (P = 10 mm), see data sheets for other leads.

AM provides the ideal combination for you

  • High axial rigidity
  • Low no-load torque

Result: High efficiency and low operating temperature (see efficiency page chart)

Preload Fpr

Preload

Ball screws for high dynamic machine axes with changing load direction require nut preload Fpr. Especially during acceleration and braking, the balls must maintain contact with the thread profiles of the screw and nut. The preload value depends mainly on the acceleration and braking force Fai.

Standard Case

Preload Fpr approximately

0.07 · Cam

Maximum Value

Can be increased up to

0.15 · Cam

If required, we determine and adjust the optimal preload Fpr according to customer requirements for axial rigidity Rnu and no-load torque Tpr0.

Fai (perm.) ≦ Fpr · 2.83

Relationship between permissible acceleration and braking force Fai and preload Fpr

連結已複製!