Cold Heading Wire - diameter of wire and ended bolt's shank 1

[cacicu]

Hi
Question about diameter of wire:

What is the relation between diameter of wire and shank diameter which comes out of cold heading process after bolt is finished? If I ask the same question in other way, how many times does the diameter of wire need to be bigger or smaller comparing to shank of bolts that comes out from cold heading machine?

If there is no general rule then at least approximate number would be useful...

Thank you.

 

[CoryPad]

It varies quite a lot based on the process sequence used to form parts. They can be roughly equal (upsetting a head only) or you can have a smaller shank (shank extrusion). The smaller shank is limited by the plastic strain capacity of the material, with a typical limit value for steel of ~ 30 % area reduction.

 

[cacicu]

CoryPad "process sequence"? Its just one (at least one main before thread rolling comes if required) process - cold heading. You mentoined bolt's head. I didn't mean head, I was asking about diameter of shank of bolt.

Regarding the head, I already know the general rule which says; out of many possible wires should be chosen the one, which has approximately 2,25x smaller (!) than the diameter of head of finished bolt that comes out from cold heading machine.

Source:

http://www.cartech.com/techarticles.aspx?id=1550

At the bottom of the site says twice but my own further research (don't remember exact link) "said" 2,25x.

But again: this is not my question, I have already know this before I opened this topic. I am asking about the diameters shank versus wire.

Also I don't know what you meant with steel. I was asking about wire in whichever material it is made. I cannot think of any idea what you wanted to say with "area reduction".

Will repeat my question on one, totally random chosen, example:

Lets say machine is creating bolts M5x3,5. The 3,5 is a matter of second condition of wire's diameter but im asking about first condition.
My repeated question is: which diameter of a wire do I have to choose so out of cold heading machine will come bolts with diameter 5mm? I doubt there is any formula but at least approximate number with clearly understandable word if is smaller or bigger would help.

Side-question which is a way less important to me than above one, but would still appreciate the answer: Since I stated the type of bolt, does it matter which material of wire do I choose if I only know bolt type?

 

[TVP]

cacicu,

There are multiple "process sequences" that can be used to manufacture the exact same fastener by the cold heading process. The simplest involves merely upsetting a head on the wire, where the wire size is essentially the same as the expected, finished shank diameter. More complex processes use 4, 5, or even 6 dies to make more complicated shapes, which involve upsetting the head as well as extruding the shank (reducing its diameter). This is what CoryPad mentioned in his response. I have attached some links to additional information on this subject, which should give you more insight into the process:

http://www.semblex.com/files/TheColdHardFactsofColdHeading-Semblex.pdf

http://www.acument.com/northamerica/products/catalog/coldformedspecials.pdf

http://www.nagform.com/Movies/108 Metal Forming Systems.pdf

http://www.lft.uni-erlangen.de/SEIT...ations/onder/ICFG Shanghai NORM FASTENERS.pdf

 

[cacicu]

TVP you said "where the wire size is essentially the same as the expected finished shank diameter". Yes this is the answer that I needed but on the source, whos link I provided, says that diameter of wire must be larger than diameter of bolt's shank which comes out from cold heading machine. However it doesn't say how much larger it should be. But you are saying now it should be approximately (!) the same. So I think this should be correct therefore. Still confused a but but I will believe you and not source which I provided. If im adding the word "approximate" it cannot be so wrong anyway.

Thank you for your pdf links. They have a lot on this topic. Now Im going a bit offtopic now from this post what I wanted to ask but still:
Would you suggest any similar pdf files / links / explanations for the rest of bolt manufacturing processes:

thread rolling (old Ingramatic machines such as this one:

http://www.tkg.si/uploads/Image/vijaki/ingramatic.jpg)

milling
thermal treatment
surface treatment

Im interested just for bolts manufacturing.