With what torque are nuts for Disc Springs tightened?

If a disc spring is preloaded by means of a threaded connection (e.g. for temperature compensation), how is the torque calculated for loading the disc spring?

• The formula is: F1*Pi*2*l/P=F2
• F1 = force on lever arm in N
  Pi = 3.14
  l = length of lever arm in mm
  P = thread pitch in mm
  F2 = force in axial direction (i.e. in the direction of the load on the disc spring) in N
  MD = torque in Nmm
• or F1*l=F2*P/Pi*2
• or Md=F2*P/Pi*2
• When putting the torque into the screw-thread-system the friction factor has to be taken into consideration.