eseemann

Has anyone tried cold working a leaf spring?

36 posts in this topic

The horizontal DoAll 916 at work went through a fork I cut for a friend  in 45 seconds. 

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Will do/

5 hours ago, BIGGUNDOCTOR said:

The horizontal DoAll 916 at work went through a fork I cut for a friend  in 45 seconds. 

Cool! 

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916 DoAll Mmmmmmm, I have saw envy!

Frosty The Lucky.

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One thing that I did not like about that saw was that it twisted the blade 90° which made it impossible to look straight down on it. Other than that it did a great job.

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Yes.. They can be cold worked to adjust spring arc or sag..    It is done completely cold..  Even eye forming is done cold..

I've been to the spring shop and have watched them do both trailer and truck springs this way..  Basically when they roll the eye it is now cold work hardened and will not open back up.. They then put in the bushing on a press. 

This was done on brand new springs and not used material..  I don't know what the base material alloy was I didn't ask.. I assumed it was 5160 but again I never asked.. and I don't know if the beginning material was annealed or not.. 

 

 I have seen so many leaf spring failures and cracks, you wouldn't catch me hammering on a used one in the cold condition worried it would snap off and hit me in the head.. 

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Jennifer: Did you note the date on this thread? :) What you say is true across the board. 

Spring shops: arc, turn ends, punch, drill and rivet cold because they're using new stock and it's annealed at the mill. They heat it if they need to do any hammering though. I routinely drill and saw old springs as found with a band saw and HS drill bits. I do nothing special just wire brush the cut or drill area first, grit really takes the edge off cutting tools. A spring heat treatment isn't to make it hard, the temper is drawn almost blue so it has a high incidence of rebound, hard is a B-A-D thing in a spring. I spent some time keeping out of their way and picking up tips about springs at an Anchorage spring shop. I still have trouble believing how they heat treat leaf springs and am not going into it it'd just confuse folk here. Heck, I'm still confused the method shouldn't work but they've been in business for more than 50 years.

Frosty The Lucky.

 

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On 27/05/2017 at 8:19 PM, Frosty said:

snip... I still have trouble believing how they heat treat leaf springs and am not going into it it'd just confuse folk here. Heck, I'm still confused the method shouldn't work but they've been in business for more than 50 years.

Frosty The Lucky.

Oh do tell!...Nothing wrong with more information however puzzling...somebody else on here might find the pattern and logic...

Alan

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Okay, you asked for it Alan. After the springs were formed they were brought to critical temp in a temp controlled furnace and quenched in water. Then immediately after quench they were heated to a dull red in another temp controlled furnace and quenched in oil.

How's THAT for heat treating that doesn't make sense? Their heat treat worked fine, where I worked the heavy duty shop sent all our spring work to this company. They don't or didn't make coil springs only leaf.

The more you think about that the more you might start to wonder about the whole, "Nothing wrong with more information," philosophy.

Frosty The Lucky.

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Seems to contradict the old saying "If it's crazy and it works; it's not crazy" alright.  I would like to have a metallurgist weigh in on this too!

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I will also be interested to hear a metallurgists opinion...

My first (non metallurgically informed) thoughts were that the first heat was to even out the worked and nonwork hardened areas by recrystallising, and providing a regular homogenous starting point with a known grain size.

The Progen steel I have is touted as no need for temper even with a water quench...I usually oil quench my press punch-and-drifts made with it and do not temper them.

Metallurgists, please explain....?

I was idling around the information super highway a couple of weeks ago and found an interesting site...with some information about heat treatment...I was researching stress relieving of 70/30 brass. He has a few papers of a metallurgical nature which may be of interest...

http://practicalmaintenance.net/?cat=10&paged=2

Alan

 

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I dont think its all that odd, I doubt its straight water. But spring temper  temps are way way higher than most of us go.  and tempering in the 400 to 600 C range makes sense.

 I temper crossbow prods at 430C. In this state the behave elasicly within their elastic limit and can be altered by bending them beyond that.

 you are tempering all the way up untill subcritical anneal (high temp temper of martensite) up in the 700C's for normal carbon steels.

 A lot of spring alteration is done post HT.

 I also know of one person killed from straightening a spring under a hydraulic press......so what industry does in a repeated and knowledgable way is not the same as having a go in the shop.

 

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