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How to build a 50k ton forging press

construction-physics.com

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Re: How to build a 50k ton forging press

#111

Post by wizardforhire »

HPsquared wrote: post #31
hwillis wrote: post #20

> Forgings have the added advantage of variable grain direction which generally can be tailored to the stress patterns of a specific design. This is a super underappreciated fact! It's often repeated that forging is just stronger, but just squishing steel does NOT make it stronger. Forging a part is so much more than just smashing it into a shape. Steel cable is made of pretty ordinary steel which is stretched 100s o…

This effect also applies to polymers! Perhaps even more so. Take a polyethylene bag (LDPE) and stretch the material in one direction. You might notice the material becomes thinner but also stronger. This is due to the polymer chains becoming aligned. Eventually you get "drawn fibers" where the molecular strands are aligned with the fibers for optimum tensile strength.

This is exactly what dyneema is only with hdpe.

Re: How to build a 50k ton forging press

#113

Post by kragen »

rlonstein wrote: post #109
kragen wrote: post #81

Earlier quoted context omitted.

there's a lot of shade-tree mechanics who have successfully rebuilt engines with thousands of parts. essentially figuring out how to rebuild an engine is similar to figuring out how to build one from scratch, which is within human capacity, particularly with background knowledge. but the guy rebuilding the engine has a lot of hints granted, he'll probably fuck up his first two or three pretty good without haynes or c…

> granted, he'll probably fuck up his first two or three pretty good without haynes or chilton Given the assumptions, inaccuracies, and mistakes I've seen in some Haynes and Chilton manuals they'll probably fuck up with them. Factory manuals are usually worth the price (Honda's are, KTM's not so much).

i certainly did. haynes is no substitute for clue

Re: How to build a 50k ton forging press

#114

Post by myself248 »

01HNNWZ0MV43FF wrote: post #55
HPsquared wrote: post #31

Earlier quoted context omitted.

This effect also applies to polymers! Perhaps even more so. Take a polyethylene bag (LDPE) and stretch the material in one direction. You might notice the material becomes thinner but also stronger. This is due to the polymer chains becoming aligned. Eventually you get "drawn fibers" where the molecular strands are aligned with the fibers for optimum tensile strength.

That makes sense, if I don't rip open a bag on the first try it'll just stretch and never open

Stretch it in one direction, then grab in the middle of the stretched area and pull sideways, and it pops open like nothing.

Re: How to build a 50k ton forging press

#115

Post by hinkley »

buildbot wrote: post #91
hinkley wrote: post #38

Earlier quoted context omitted.

I saw a guy weld 1.5 or 2 inch plate once to repair the bucket on a giant bulldozer. That was… interesting. I was trying to figure out why he left such a big gap until he started welding. He had to fit the head in to lay down layer after layer of welding bead to join the pieces at full depth. How would you weld even one foot of steel?

Explosively? https://en.wikipedia.org/wiki/Explosion_welding

OMG. Are you required to slap it and say, "That'll hold" afterward?

Re: How to build a 50k ton forging press

#116

Post by hinkley »

kragen wrote: post #103
hinkley wrote: post #92

Earlier quoted context omitted.

There is a lot of stuff you can do when it’s pass fail. As a pro you have a time limit and you’re bad if you can’t rebuild in X hours. My dad will tell you I helped him rebuild a bike coaster brake at 14. But the truth is the only decision he made was to buy the repair kit. I got rags and laid all the parts out like an exploded diagram, we cleaned them or swapped them and they went back in the way they came out. I wo…

yeah. thank god for sheldon brown

I was more of a Brandt boy myself.

Re: How to build a 50k ton forging press

#117

Post by hinkley »

WheatMillington wrote: post #99
hinkley wrote: post #96

Earlier quoted context omitted.

Does every car mechanic have the entire Chilton’s catalog or do the mechanics just have to memorize things or look them up on the Internet? My understanding is it used to be a little A and a lot of B, and now it’s a mix of B and C

I was using the engine example as an analogy in an apparently failed attempt to help you appreciate the complexity involved. Mechanics in general will feel their way around an issue, but almost universally have access to paid repair databases when non-intuitive and complex issues come about.

You might recall that we're all talking about manufacturing equipment that was exfiltrated as war reparations.

I'm much less convinced than you are about the availability of accurate and detailed manuals. Which is why I keep steering the conversation to more murky engineering projects.

But I do want to circle back to say that I did at some point higher up gloss over the importance of things like torque and clearances. I'm not trying to say that those are things you can just intuit. Even if we could both probably dig up an old mechanic who tightens things by feel.

Re: How to build a 50k ton forging press

#118

Post by bacon_waffle »

kragen wrote: post #81
WheatMillington wrote: post #78

Earlier quoted context omitted.

Your viewpoint is rather naive in the mechanical world. OK it's enough to assemble a coffee table, now try an engine with 2,000 parts. Without a manual how can you set bearing clearances? How do you know how much thrust clearance there should be? How do you know which way up a piston ring goes, or how much torque to apply to a head bolt? Machines are extremely complex, and that's before you even touch electronics and…

there's a lot of shade-tree mechanics who have successfully rebuilt engines with thousands of parts. essentially figuring out how to rebuild an engine is similar to figuring out how to build one from scratch, which is within human capacity, particularly with background knowledge. but the guy rebuilding the engine has a lot of hints granted, he'll probably fuck up his first two or three pretty good without haynes or c…

I've rebuilt several motors, transmissions, various other mechanical contrivances. Sometimes with decent documentation, sometimes not so much. Also done a bit of amateur machining, and worked as an engineer on physical products.

Under no circumstances would I claim that rebuilding a motor was essentially figuring out how to build one from scratch. In software, maybe that's like claiming that figuring out how to configure a new Linux box is essentially the same thing as figuring out how to write an OS.

Re: How to build a 50k ton forging press

#119

Post by hwillis »

pfdietz wrote: post #33
hwillis wrote: post #20

> Forgings have the added advantage of variable grain direction which generally can be tailored to the stress patterns of a specific design. This is a super underappreciated fact! It's often repeated that forging is just stronger, but just squishing steel does NOT make it stronger. Forging a part is so much more than just smashing it into a shape. Steel cable is made of pretty ordinary steel which is stretched 100s o…

I wonder if it's possible to do additive manufacturing with pre-elongated snippets of wire.

annealing, which resets the grain structure, happens at a lower temperature than melting or sintering.

Re: How to build a 50k ton forging press

#120

Post by hwillis »

samstave wrote: post #87
hwillis wrote: post #20

> Forgings have the added advantage of variable grain direction which generally can be tailored to the stress patterns of a specific design. This is a super underappreciated fact! It's often repeated that forging is just stronger, but just squishing steel does NOT make it stronger. Forging a part is so much more than just smashing it into a shape. Steel cable is made of pretty ordinary steel which is stretched 100s o…

I have had this question in my mind for decades: > "Can you forge metals in a highly controlled and directed magnetic field where you can orient the grain/alignment of atoms/fields in whatever direction you want. Further, if true, what happens when you make damascus from varying plated that have particular alignments/grains - and what are the features of this material?

> Can you forge metals in a highly controlled and directed magnetic field where you can orient the grain/alignment of atoms/fields in whatever direction you want.

This is how you make magnets. "Soft" ferromagnets have small, round grains that rotate to reinforce outside fields. "Hard" ferromagnets have permanent fields of their own and long grains that can't reorient.

Forging with a field has a very low impact on the material properties because of how weak a magnetic field is compared to the forces moving atoms- same reason steel loses its magnetic properties when it gets hot.

> what happens when you make damascus from varying plated that have particular alignments/grains

"Damascene" is the layered look most often made from acid etching sandwiched and forge-welded layers of different steels. Damascus is a single alloy for which the pattern is named.

Since in both cases the material is melted together, it's far too hot for any magnetic properties to have any impact.

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