Talk:Rolling (metalworking)/Archive 1

History of Hot Rolling

This text (probably originated by Steel worker jim) was deleted from the very end of the article in September 2006 (look for the unkind edit comment about 'removing unsourced weirdness' ), and it is to this (I think) that the rest of the comments in this section refer. The text is unaltered (apart from one typo at the end) except for the enforcing of the paragraph breaks as intended by the original author.
(EdJogg (talk) 12:07, 14 April 2008 (UTC))

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HISTORY OF HOT ROLLING IN THE 20TH.CENTURY!

At the turn of the century, hot rolling mills consisted of several mills lined up in a row, next to each other, and were powered by a single steam engine. Each sheet was rolled one at a time. Because one steam engine powered many mills, called a sheet mill train, the mills ran in only one direction, and were not reversable. Steam engines took too much time to reverse. The sheets began as plates about 3/4 of an inch to 1 inch thick, 12 to 16 inches long, and 24 to 80 inches wide. These plates weighed between 140 to 200 pounds each. Each mill had a furnace behind it and the plates were heated to nearly the melting point making them soft. A worker would use a large set of tongs and manhandled the plate from the furnace to the mill. The mill had two rolls, positioned one above the other, and the plate was fed into these rolls by the worker. Because the mills were not reversable, workers on the back side of the mill had to use their tongs to lift the now lenghtened plate up high enough to rest it on the top roll and the top roll would carry it back over to the feeder side of the mill where men on that side used there tongs to grab it and position it back on the roll table. At the same time the rolls were moved closer together and the plate was passed through the rolls again. It usually took about 20 to 24 passes before the correct thickness (gage) was reached. The longest sheets were about 16 feet long and if the finished sheet was 8 feet or less in length, sheets were folded at some point during the process and rolled folded thereby yeilding 2 sheets when finished. Because of this, the mill crews never had any easy orders to fill. Many times the sheets had to be reheated so the mill crews had to manhandle them back into the furnace. As the sheets became longer the men on the back side had to grab the sheets at the end, with tongs, and had to walk at a brisk pace backwards as the sheet rolled through the mill. If he fell down, the red hot sheet would roll over top of him usually tearing into his belly or neck igniting his body fluids and proably killing him. Surprisingly, not many men met this fate. A new hired man was told of these dangers, by his fellow workers, and warned, "if you fall your fired". The bewildered new hire was then told "we won't actually fire you if you don't burn up and are able to come back to work". This process of rolling sheets was very expensive and the work was brutally hot and hard. As hard as it was, however, these jobs were desired because workers were paid a good bonus on tonnage, so the pay was good.

Over the years many attempts were made to roll steel through a series of mills, placed in a straight line, but met with failure. This process was finally perfected in Ashland Kentucky at an Armco Steel plant, now known as AK Seel, in 1921 under the direction of John Tytus. John Tytus was from Middletown, Ohio where Armco was founded. Middletown had several paper mills that John had experiance in and paper was rolled in a continuous process. John was able to convince Armco that if paper could be rolled in a continuous process, then so could steel. Because the mills had to be placed about 8 feet apart, each mill had to be run at the correct speed and the proper tension, on the ever lengthining strip, had to be applied between each mill or you would either tear the strip into, or the strip would buckle and, in either case, the fast moving strip would pile up between the mills. This can still happin today although not often. When this happined equipment was often damaged, and the steel would have to be cut up, using cutting tourches, and the strip, now scrap, would have to be removed. The strip mill usually had 5 to 7 mills spaced about 8 feet apart and when the steel entered the first mill it was about an inch thick, with each mill reducing the thickness and upon passing through the last mill being the correct gage, usually between 1/16 to 1/4 inch thick. The steel entered the first mill at the speed of a slow walk and came out the last mill at a speed of 30 to 40 miles per hour. After the speeding strip leaves the last mill it is cooled by a series of water sprays and then coiled.

Many people credit the Bessimer Converter and the Open Hearth Furnace processes for making the production of steel economical, and while this is true, if it were not for the invention of the continuous hot strip mill, this steel could not be processed into sheets economicaly, and things made of sheet steel such as automibles and appliances would be much more expensive. This process also made possible the continuous cold strip mill, usually the next step in sheet steel production. It is after the cold rolling process when the coils are cut into sheets. This same process is used to roll aluminum.

Today some of the larger hot strip mills, in conjunction with about 5 to 6 roughing mills process slabs that are 12 inches thick, 24 feet long that weigh almost 80,000 pounds into coils of steel. Roughing mills reduce these slabs from 12 inches thickness to about 1 inch of thickness prior to entering the hot strip mill. The roughing mill process was in place before the invention of the hot strip mill and before it's perfection the reduced slabs were cut into the plates mentioned above. When the hot strip mill was perfected, the hot strip mills were added down line from the roughing mills. Today the entire process of rolling a 40 ton 12 inch thick slab into a coil takes about 120 seconds start to finish. Some coils contain over 1/4 mile of steel. Some of the modern mills can roll close to 900 tons per hour.

Now, steel makers are trying to figure out how to accomplish this task by pouring liquid hot metal into a caster and have the finished coil emerge without using rolls at all. If this process is perfected the modern hot strip mill, a very expensive thing to build and maintain, will become obsolete overnite. Many people think this will become reality soon. What next? Watch out if you're in the plastic industry.

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If you have any questions about the above article email me at "jimdavis11@hotmail.com" and I will try to answer them. (Comment by Steel worker jim moved from article space by — Graibeard ^(talk) 10:58, 20 July 2006 (UTC))

Hi Steel worker jim. That's a nice addition to the article.

I've run through the article, saved my copyedits as one edit and then saved the second edit with whitespace only changes. This is so you can review what I've changed when you do a diff and see if the changes are appropriate.

Questions:

1. While I think I know what you mean here this meant that the workers did not have any easy orders to fill. Could you clarify it, I'm assuming this refers to the folding of the sheet. Was this an extra step not required when the sheet was over 8 feet long?
2. the strip would tear or buckle and the result would be cobble. Is cobble a steel worker term, perhaps slang? If it is then it's worth clarifying, if it's not then perhaps a more suitable word/phrase can replace it as it leaves the reader guessing its meaning. I can picture the end result if the speeds are different, but the word didn't help.
3. I've added subheadings for bar mill and hot mill, are they in the right place? Am I reading the article correctly when you mention the terms? The bar mill process was already in operation prior to the invention of the continuous hot strip mill. Before the invention of the hot strip mill the bars were cut into the plates mentioned above.
4. Do you have a reference for While this is true if it were not for the continuous hot strip mill the production of sheet steel would not be economically possible, and our standard of living, would not be as we know it today. While I can see the truth in it, it's such a bold statement that a reference to support the statement would add credibility to it. — Graibeard ^(talk) 11:46, 20 July 2006 (UTC)

My background is in metallurgy having managed hot and cold rolling mills. Bear with me as this is my first attempt at adding to Wiki content (Metally 12:42, 24 August 2007 (UTC)).

Merge Work rolls into this article

I concur with the proposal to merge the article work rolls into this one. Risker 19:39, 29 October 2006 (UTC)

How come?

so how come after the metalhas been cold worked to a certain stage does the hardness start to decrease?

it becomes more brittle as it is repeated cold-rolled due to strain hardening. Additionally, all metals anneal over time slowly, the rate is simply much slower at lower temperatures-- perhaps this is what you are thinking of? siafu 14:01, 24 April 2007 (UTC)

Logic error in article

"Quarter hard metal can be bent entirely back on itself, while full hard can only be bent 45°.[1]"

Given a long enough piece of full hard metal, I can bend it more than 45°. - This above sentence probably speaks of the relation in which equally long pieces of quarter-hard and full-hard stand to each other, but still it would be quite topical to point out approximately how long these pieces are for a given material.--Ceriel Nosforit 17:22, 14 July 2007 (UTC)

This statement is very specific to an alloy, it has no real value to the article other than to qualitatively illustrate that cold work makes a metal harder. I have removed it, but have replaced the content with information presented in a more acceptable fashion.Iepeulas 03:19, 7 August 2007 (UTC)

History of Hot Rolling -- 2

I came to this article to discover when hot rolling was introduced. Where is the history section? Who invented the process? When? Where?

(Frustrated) -- EdJogg (talk) 12:13, 14 April 2008 (UTC)

Sweet iron

Does explanation of the term "sweet iron" belong here? --Una Smith (talk) 23:52, 14 November 2008 (UTC)

Great minds! I had the same question. Folks, can anyone tell us what, metallurgically, "sweet iron" is? It is commonly used to make horse bits like this one ( which also has copper inlays). One source describes it as "...sweet iron, also known as mild steel and cold-rolled steel. This metal alloy is slightly softer than stainless steel, and instead of a perpetual shine, will quickly begin to rust." We'd like to kill some red links by explaining what it actually is. Another source says, "Sweet iron is likely not pure iron, but a mixture of iron and carbon combined to create some form of a carbon steel."-- but they sound like they don't know for sure. Help?? Montanabw^(talk) 05:39, 16 November 2008 (UTC)

I can tell you that it probably doesn't belong here. Just shooting from the hip here, it sounds like it's a certain formulation of carbon steel, probably given the specific name "sweet iron" because of its application. See silver steel for a similar premise. As such, I recommend that we continue this discussion over at the talk:steel page were you also placed an inquiry. Wizard191 (talk) 16:46, 16 November 2008 (UTC)