Question

For the screw-operated press, the screw has a single 1⁄2-10 ACME thread, both in a right-hand and

left-hand orientation, as shown. The handle rotates counterclockwise at 45 rpm to drive the pressure

plate downward. In the position shown, with β = 25°, determine the velocity of the pressure plate.

Left-hand thread Right-hand thread O Pressure plate 2 2

Answer 1

Solution-

Calculating the pitch P of screw -

M: L o Here, Number of threada per inch, in Pitch , P Substitute 10 fon m fon m im the equation 10=t ta D L 10 Oliml thread

Calculating the lead of the screw-

L = Ny xp Here, Lead of the thread, L Number of threads per revolutium , Ni Substitute I threadlnev for Ny and O.lim. Ithread for L= thread xo.1 in thread = 0.1 in I reu

Now,calculating the velocity of each nut-

VBIs = L x Ws Here, Angular velocity of screw, ws. rodman an Substitute of im I rev for L and 45 rpm 0.1 im X 45 BIS mim 4.5 im mim

Velocity diagram of different parts-

25 J CIB 닝 Vs us 1300 i Î 25 B Jels Here, ardois represents velacity B with respect af mut Drew Vcis represemis the velocity of platea with respect to mut B

Now,finally

ralulate the value of VB QA Ahown below! tam 25. UBIS Substitute 4.5 in. I mim for Ubis im the equatican Vols Sim 25. 4.5 0.423 10.638 im. I mim calculate the value of Vi by applying shawm belowk Dime rule B simas" sim 130 Vc = Aim 130 x Dim 25 Here. Velocity of plate , ve substitute 10.638 im. I mim for VB in the eam Vc = sim 130 X 10.638 sim 2 s. = 119.30 in. I mim

So,the velocity of the pressure plate is 19.30 in./min (downwards).