Скачать или смотреть Stresses in Power Screws: Analysis of Torsion, Compression, and Thread Stresses

Stresses in Power Screws

Stresses in the body of power screw
A1. Shear Stress due to torsion
A2. Compression stress due to the load




Stresses in Threads
B1. Bending stress at the root of thread
B2. Shear stress in the middle of thread cross section
B3. Bearing stress in threads

Power screw thread is in compression, causing elastic shortening of screw thread pitch.

Engaging nut is in tension, causing elastic lengthening of the nut thread pitch.

Consequently, the engaged threads cannot share the load equally.

Experiments indicate the first thread carries 38% of the load, the second thread 25%, and the third
thread 18%. The seventh thread is free of load.

To find the largest stress in the first thread of a screw-nut combination, use 0.38 F in place of F, and set nt = 1.