Design a hard steel (screw and nut) lubricated power screw for raising and lowering a load of 25 kN using a square – thread with major diameter of 40 mm, pitch of 6 mm with triple threads and a plain bronze thrust collar of 60 mm (fc=0.08) (Assume maximum friction). (a) Find the torque for raising and lowering the load. Is the design self-locking? If not, please change the design accordingly (b) Find the largest axial and shear body stresses. Also find the bending stresses (c) With a safety factor of 2, a designer has chosen the DE approach to design the power screw with Sy = 260 MPa. Is this a suitable option?

Design a hard steel (screw and nut) lubricated power screw for raising and lowering a load of 25 kN using a square – thread with major diameter of 40 mm, pitch of 6 mm with triple threads and a plain bronze thrust collar of 60 mm (fc=0.08) (Assume maximum friction). (a) Find the torque for raising and lowering the load. Is the design self-locking? If not, please change the design accordingly (b) Find the largest axial and shear body stresses. Also find the bending stresses (c) With a safety factor of 2, a designer has chosen the DE approach to design the power screw with Sy = 260 MPa. Is this a suitable option?

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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Concept explainers

Metrology of Screw Threads

Screw threads are a series of ridges having the profile of a helix. This helix profile runs continuously along the length of a uniform solid or a hollow bar of a circular cross-section at periodic intervals. These helix ridges are also formed over a conical bar. These continuous helical ridges are termed threads.

Question

Design a hard steel (screw and nut) lubricated power screw for raising and lowering a load of 25 kN using a square – thread with
major diameter of 40 mm, pitch of 6 mm with triple threads and a plain bronze thrust collar of 60 mm (fc=0.08) (Assume maximum
friction).
(a) Find the torque for raising and lowering the load. Is the design self-locking? If not, please change the design accordingly
(b) Find the largest axial and shear body stresses. Also find the bending stresses
(c) With a safety factor of 2, a designer has chosen the DE approach to design the power screw with Sy = 260 MPa. Is this a
suitable option?

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Step 2: (a) Finding the Torque required for Raising and lowering the load

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Step 3: (b) Finding the largest shear ,Axial body stress & Bending stress

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Step 4:-(C) Finding that this is suitable or not?

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