What is the max deflection angle of a double torsion spring with a 225 degree free angle (also for a 255 degree free angle)? And is this calculation based on the free angle? Also what is the cyclic lifespan? Spring specs: 17-7PH SS wire, 0.045″ wire dia, 0.255″ coil ID, 0.28″ fixed arm length, 1.29″ moment arm length, 6 coils per side, 0.346″ body length. In the installed position, the deflection angle is ~150 degrees. Thank you.
To Whom It May Consern
From the spring specifications, the maximum usable torque for a double torsion spring in the static case is The maximum usable torque for the static case of the double torsion spring was calculated from the spring’s specifications.
Since the spring is 17-7PH SS wire, the mechanical properties of SUS631J1 (JIS G4314) were used as a reference. The maximum usable angle point was confirmed.
If the deflection angle from free time is 150deg, the usable maximum stress is exceeded.
Therefore, the life cannot be evaluated.
The maximum usable angle in the static case is 79deg. The torque at that time is 137 N・mm.
The design life of a torsion spring is calculated based on the minimum and maximum stresses in the range of use, using the fatigue strength diagram (For details of the diagram, please refer to the technical and calculation information on Tokai Spring’s website). The design life is evaluated by applying the minimum and maximum stresses in the range of use. Therefore, the angle of the arm at free time is irrelevant.
The required information is the deflection angle from the free state in order to determine the minimum and maximum stresses in the range of use. The information required is the angle of deflection from the free state to determine the minimum and maximum stresses in the range used.
However, in the case of stainless steel wire, it is not possible to use fatigue strength diagrams, so it is necessary to use the literature and Therefore, it is necessary for the designer to determine the fatigue limit based on the information on fatigue limit in the literature and the information Therefore, it is necessary for the designer to make a judgment based on the information on fatigue limits in the literature and information published by material manufacturers.
BestRegards
Tokai Spring’s Support Team
