calculate pressure 1

[mfgenggear]

if I have a ring that is
16.00" OD x 13.00 ID x 2-1/4 thick
Material is 9310 steel heat treated to 35 HRc

if I heat this ring to 1500 deg F
To expand this ring .010 bigger & to round it up.using an expanding mandrel with segmented shoes.
what is the formula used to calculate the pressure in PSI.

 

[metengr]

mfgenggear:
Not sure what you are asking here -
hydraulic pressure required to permanently expand the ring at 1500 deg F?

Second comment - if you heat the ring to expand it you will soften it because you have exceeded the original tempering temperature for this material. You will need to reheat treat this ring after hot working to expand it.

 

[mfgenggear]

Metengr

sorry for not explaining correctly

the ring has been machinability heat treated.(interm heat treat for machining)it is not the final heat treatment.
how ever there is abundance of stock on all surfaces.
I am trying to calculated at the second heat treat operation how much force is required to keep this ring
round during heat treat and hardening operation.

yes it's for the intial setting, hydraulic pressure required to expand the ring. usally it's a pattern that needs to be developed. I am trying to calculate pressure required.

again sorry for not explaining my question correctly.

 

[IRstuff]

It looks like you're essentially doing a forging, so wouldn't the force required be similar to what a normal forging process might require?

TTFN

FAQ731-376

 

[mfgenggear]

IRstuff

there will be pressure from a ram that will
press onto a tapered mandrel at the center of the
segmented shoes. the mandrel expands the shoes
beacause the mating surfaces are tapered 30 Deg F
thus it puts pressure on the ring from the ID.

thus expanding the ring & rounding up.

 

[metengr]

mfgenggear;
I would heat the entire ring to at least 1700 deg F, and take full advantage of reducing the flow stress for hot working, slow cool and reheat treat for final properties.

You can calculate either the force or pressure based on overcoming the flow stress at temperature. If you know the mandrel size (area), you can calculate the force required to enlarge the ring, assuming you are hot working the entire ring at one time.

You will need to account for some localized frictional affects between the hot metal surface and mandrel (+10% value of flow stress as an approximation).

 

[mfgenggear]

Metengr

Is it not the deformation of the ring part of the equation & not the mandrel?

deformation = force*length/area*Modulas of elasticity

what is the modulas at 1700 Deg F?

is this on the right track

Thanks

 

[metengr]

The mandrel area is what is used in determining forces necessary to hot work the material. Modulus is not used in hot working it is flow stress; in other words, you need to calculate the force required to overcome the material's flow stress (yield strength at temperature) to produce permanent deformation. This is why you hot work material, so that forces are lower.

 

[mfgenggear]

ok trying to obtain elevated tensile stress results (flow stress)
called steel suppliers and no success.

if someone happens to have them could you post a copy here!

now I reviewed my old books & googled and no success
on any other Information on this subject.

so the best I can fiqure is

stress = force/area

so then force= area*stress

 

[metengr]

mfgenggear;
At 1700 deg F you will be in a fully austenitized condition prior to hot working, and I would estimate the yield strength would be 10% of the RT value for this low carbon alloy steel.

 

[mfgenggear]

good deal
thanks metengr

 

[arunmrao]

mfgenggear;At 1700 deg F you will be in a fully austenitized condition prior to hot working, and I would estimate the yield strength would be 10% of the RT value for this low carbon alloy steel.

Metengr, I have spent a long time this evening to improve on the values given by you. I give up,the best literature support that I get is 30% reduction(from RT value) at 500C, 10% of RT values at 800C and nothing beyond that temperature. Perhaps oxidation and grain growth become dominant factors.
Hats off!

Learn the rules,so you know how to break them properly.
Dalai Lama

_____________________________________

 

[mfgenggear]

just to let every one know I found this formula for strech forming of sheet metal skins

F=(Ys+UTs)/2*A
or 0.7TL(UTs)
T= thickness
L=total length
UTs=Ultimate Tensile

use to do similar at General Dyanamics.
it may or may not be revelent but I posted it.

Please do make suggestions on the above formula.

The ring I have above is a real project.
I need to get a handle on the starting pressure of the expanding mandrel.