Answer:
54mm.
Explanation:
So, we are given the following data or parameters or information that is going to assist in solving this type of question efficiently;
=> "A square-thread power screw has a major diameter of 32 mm"
=> "a pitch of 4 mm with single threads"
=> " and it is used to raise a load putting a force of 6.5 kN on the screw."
=> The coefficient of friction for both the collar and screw is .08."
=> "If the torque from the motored used to raise the load is limited to 26 N×M."
Step one: determine the lead angle. The lead angle can be calculated by using the formula below;
Lead angle = Tan^- (bg × T/ Jh × π ).
=> Jh = J - T/ 2. = 32 - 4/2. = 30mm.
Lead angle = Tan^- { 1 × 4/ π × 30} = 2.43°.
Step two: determine the Torque required to against thread friction.
Starting from; phi = tan^-1 ( 0.08) = 4.57°.
Torque required to against thread friction = W × Jh/2 × tan (lead angle + phi).
Torque required to against thread friction =( 6500 × 30/2) × tan ( 2.43° + 4.57°). = 11971.49Nmm.
Step three: determine the Torque required to against collar friction.
=> 2600 - 11971.49Nmm = 14028.51Nmm.
Step four = determine the mean collar friction.
Mean collar friction = 14028.51Nmm/0.08 × 6500 = 27mm
The mean collar diameter = 27 × 2 = 54mm.
