Power Screw Example 3: Finding stresses on the body and threads of a power screw скачать в хорошем качестве

Power Screw Example 3: Finding stresses on the body and threads of a power screw

Power Screw Example 3: A power screw with square threads is used to raise a load. The screw has a major diameter of 30 mm and a pitch of 4 mm with triple threads, If the coefficient of friction of collar and screw are both 𝑓=𝑓_𝑐=0.05, the collar diameter 𝑑_𝑐=50 mm and F=65 kN. a. Find the thread depth, thread width, pitch diameter, minor diameter and lead. b. What is the torque required to raise and lower the load? c. Is the screw self-locking without the collar? d. Find the efficiency during lifting the load. e. Find the body stresses, torsional and compressive. f. Find the bearing stress on the first thread. g. Find the thread bending stress at the root of the first thread. h. Find the transverse shear stress due to shear load at top of the root. i. Determine the von misses stress at the root of the thread.