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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

#151

Post by krisoft »

hinkley wrote: post #117
WheatMillington wrote: post #99

Earlier quoted context omitted.

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 don't understand the problem. You take the equipment, the manual, the guy who used to read the manual and maintain the equipment and the guy who wrote the manual and designed the equipment.

Re: How to build a 50k ton forging press

#152

Post by jessebro »

NavinF wrote: post #135
libria wrote: post #133

Earlier quoted context omitted.

Assuming these terms are all correctly spelled, this has to be the shortest sentence I've understood the least of on HN. Guess I've got some googling to do.

UHMW = ultra high molecular weight. Each molecule is literally heavy because they have a lot of atoms. PE = polyethylene. The most popular plastic on this planet. HDPE = high-density polyethylene. One of the most common plastics. Milk jugs, glue bottles, etc. Stick some UHMW tape on anything that needs to slide easier. Its surface is quite slippery

HDPE is also what Nalgenes and the like are made of (or used to be anyway), and is very popular for storing chemicals as well. It is very nearly completely inert.

Re: How to build a 50k ton forging press

#153

Post by jessebro »

knodi123 wrote: post #59
droopyEyelids wrote: post #47

Earlier quoted context omitted.

This has been such a frustrating culture war definitional argument.

Not necessarily a culture war thing. People who aren't familiar with the subject might take "unskilled" in the plain-english sense, as a pejorative. And who can blame them? We're english speakers before we're technical speakers. Make gracious assumptions.

Anyone who has worked in a job classified 'unskilled' generally doesn't need a pejorative to feel unloved. It's the nature of the game.

Digging ditches generally sucks, same as I imagine being a striker, but most anyone can do it (until their body gives out, anyway, which in some cases is 'immediately').

Re: How to build a 50k ton forging press

#154

Post by jessebro »

hinkley wrote: post #49
tra3 wrote: post #43

Earlier quoted context omitted.

For context, I work on my car a bit, and the shop manual for it is hundreds of pages (thousands?). Now scale it up to a factory, maybe without manuals. Disassemble, crate it, assemble it 5000 miles away. Based on my software experience, I can sort of go in blind and figure out how a system functions. I suppose that translates to real world too..

There’s a UX school that says that if the user needs the manual you fucked up. I mostly subscribe to that school. Mostly. It drives my family nuts that I will assemble a piece of furniture without reading the instructions. But the thing is with a little mechanical sympathy, and a well designed product, there’s only one sensible way for the parts to go together, and if you organize them right while you disassemble it…

Better hope they done have one set of 50mm bolts which are mild steel, and another set that are hardened high tensive steel that aren't clearly marked and the same length!

Or you're going to have quite an adventure when you go to do your thing and a random selection of bolt heads come pinging off at you at mach 5.

Re: How to build a 50k ton forging press

#155

Post by jessebro »

krisoft wrote: post #151
hinkley wrote: post #117

Earlier quoted context omitted.

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 don't understand the problem. You take the equipment, the manual, the guy who used to read the manual and maintain the equipment and the guy who wrote the manual and designed the equipment.

Did we mention that the manual was burned, and the guy and the guy who wrote the manual died in the explosion that burned the manual?

It was at the end of a massively destructive war of annihilation.

Re: How to build a 50k ton forging press

#156

Post by jessebro »

hinkley wrote: post #38
jcgrillo wrote: post #25

Earlier quoted context omitted.

well the next time I need some 130ft thick brackets I'll ask them whether I can use it after hours or on the weekend EDIT: or, according to hwillis' math, 2.5ft thick. I guess those could be useful for anchoring a zipline to the moon or something.

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?

A lot of the armor plate on the big battleships like New Jersey were welded. Some of those are over a foot thick.

It would take a LOT of passes.

Re: How to build a 50k ton forging press

#157

Post by jessebro »

IshKebab wrote: post #71
spenczar5 wrote: post #30

Earlier quoted context omitted.

Yes, I said “impractical”, not “impossible”.

You said > The spokes are really hard to make precisely with machining That is not true.

Back in the days of manual machining it was definitely true. CNC, especially modern 5+ axis high speed high rigidity machines are god level cheating.

Re: How to build a 50k ton forging press

#158

Post by kragen »

jessebro wrote: post #152
NavinF wrote: post #135

Earlier quoted context omitted.

UHMW = ultra high molecular weight. Each molecule is literally heavy because they have a lot of atoms. PE = polyethylene. The most popular plastic on this planet. HDPE = high-density polyethylene. One of the most common plastics. Milk jugs, glue bottles, etc. Stick some UHMW tape on anything that needs to slide easier. Its surface is quite slippery

HDPE is also what Nalgenes and the like are made of (or used to be anyway), and is very popular for storing chemicals as well. It is very nearly completely inert.

you cunninghammed me: nalgenes are polycarbonate, which is a lot less inert

all the polyethylenes are relatively inert, because polyethylenes are in some sense just heavy paraffins. paraffin is germanized latin for 'relatively inert'

Re: How to build a 50k ton forging press

#159

Post by kragen »

azalemeth wrote: post #148
abe_m wrote: post #110

Earlier quoted context omitted.

I'd really like to see some backing of these claims. I've seen "grain flow" claiming big gains for years in various enthusiast magazines (bike, motorcycles, cars, etc) as to why components are forged. Then I started working in engineering, and I can't find any support for these claims. For sure when a steel bar is worked down to become wire for a steel rope, it cannot be pulled to an elongation of 100x increasing str…

The best evidence for grain flow on a really atomic scale comes from what is called texture analysis in X-ray or electron-beam crystallography (or related techniques): you get a deviation in the distribution of Bragg peaks due to the fact that you have a non uniform distribution over the orientation of the unit cells within the crystallites in the bulk material. You can fit this in a spherical harmonic basis and quit…

but 1600° for tungsten is still barely above its ductile-to-brittle transition, isn't it? because that can be up to 967°

Re: How to build a 50k ton forging press

#160

Post by kragen »

bobeboph wrote: post #136
abe_m wrote: post #110

Earlier quoted context omitted.

I'd really like to see some backing of these claims. I've seen "grain flow" claiming big gains for years in various enthusiast magazines (bike, motorcycles, cars, etc) as to why components are forged. Then I started working in engineering, and I can't find any support for these claims. For sure when a steel bar is worked down to become wire for a steel rope, it cannot be pulled to an elongation of 100x increasing str…

MIL-HDBK-5 [1] is a good publically-available source for strength allowables for several aerospace alloys, including multiple directions relative to the grain for some of them. The first relevant example I found was on page 3-86, extruded 2024, 2.250 - 2.499 inch cross-section. For ultimate tensile strength, F_tu, the L (in the direction of extrusion) allowable is 57 ksi, while the LT (perpendicular to the direction…

this is a fantastic find, thanks!
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