Simulation of shearing blade life

[501560789]

Hi Guys,

I'd like to ask you for support to estimate of part life.

Real process:
Two cut-off (hardener tool steel,tested 64HRC) blades cutting the copper wire OD=2mm during serial wire production. V-edge profile blades shearing this wire with constant force and after 15k cycles new blade edge is dulled/blunted.

Is it possible to try estimate life of the blade?

All B.C.s to analysis are known like: temp, force, material etc.

Thanks you for any suggestion.

 

[mrgoldthorpe]

You've had no replies because it's not a question finite element analysis can answer. I think that tests can only do that.

 

[corus]

Can't you already estimate the life of a blade given you know the life of the existing blade/force/material yield etc.?

Tata

 

[501560789]

I am interesting of LCF fatige life estimatation by FEM ANsys of the cut-off blades for elasto-plastic material. In case of results of cycles I would like improve blade life by change material and coats, geometry modifications.

Actually I have almost all inputs for material properties, all BCs from real process.

Are you able to support my project start? Thanks

PS. At picture you can see the blades at operating conditions.

 

[corus]

I don't think it's a fatigue life problem the way you describe it, as cracking doesn't occur. It's more of a problem of gross distortion with stresses beyong yield. In the case you describe, it has been subjectively decided that 15k cycles was the life of the blade for the amount of distortion that occured.

Tata

 

[501560789]

Yes, I would like to confirm by FEA that blade life could be extended by blade redesign or material regading manufacturer design.

 

[501560789]

any ideas, suggestions?

 

[EdDanzer]

I doubt this is a structural problem. It is a wear problem.

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com

 

[501560789]

In which way is possible to calculate wear of material??

 

[mrgoldthorpe]

Are you a student and doing a project where you've been asked to do FEA to try to resolve this problem? You keep referring back to calculations, rather than undertaking tests.

In order to use FEA to try to solve this problem you would need a model of the blade wear process. This would require a range of test results and detailed analysis of the cutting and wear process for different blade materials or surface treatments. It seems to me that you have a limited range of test results and no such model.

If I were asked to improve the life of these blades for real I'd take a look at some of the metal coating techniques available, such as those provided by Bodycote Metallurgical Coatings:

http://mc.bodycote.com/?OB=112&POB=258&ID=618

 

[501560789]

Hi
Thorpe Thank you for respond.
I am not a student - unfortunately.Actually I'm testing wear process upon material coats and axial displacement, no results yet.
Basically I have high opportunity to change blades and propose the best solution to extend the wear process.

Which surface treatment process could be the best for these blades? (tool steel material).

Is it possible to simulate of material coat in ie. ANsys?

 

[501560789]

I have tried with TiCN and TiN coats on blades - no influance on wear effect.

How to edit a post after submit in this forum??

 

[IRstuff]

In general, the biggest bang for your development buck in a blade application is the blade profile. You need to look at HOW the blade is dulling over time. You say V-edge as if that was the end-all and be-all, but there are an infinite number of possible V-profiles, and it should be obvious that certain ones, like the thinnest ones that would have nearly zero life, while extremely blunt ones would have substantial life, but poor cutting properties. Somewhere inbetween is the optimum shape for the maximum life.

Then you need to look at whether a single V-shape is really as good as it gets. Many cutting knifes have compound V-shapes, and potentially, an optimum shape might be an ogive.

TTFN

FAQ731-376

 

[501560789]

IRstuff, thanks for reply.
Blade is dulling across the blade edge. It is a plastic surface yield deformation after 8000 cuts. After that cycles blades begin to not cut all lateral copper wire and stards to tear and bend the wire.
V-blades always have been used same as now-but not for such of high production. These type of blades are recomended by customer for this type of wire.

Of course, I would like to simple check the same blades but with different cutting edge angle.
Is there posibility to simulate this wear process by FEA??

Thank you in advance.

 

[IRstuff]

Is there any correlation with respect to the cutting rate, i.e., if the same number of cuts were made over 10 days instead of one, is the blade life unchanged?

I think you're getting overly hung up on using FEA for this analysis. FEA analyzes bulk properties, and cannot simulate permanent distortion, since the element positions are set, apriori, with semi-elastic connections. I'm not even sure how you'd model a shearing operation using FEA.

TTFN

FAQ731-376

 

[kellnerp]

I think you're getting overly hung up on using FEA for this analysis. FEA analyzes bulk properties, and cannot simulate permanent distortion, since the element positions are set, apriori, with semi-elastic connections. I'm not even sure how you'd model a shearing operation using FEA.

Say what? Ever looked at Abaqus Explicit? Elements can detach from the model if necessary. Almost any standard Non-linear solver will simulate permanent distortion (plasticity).

TOP
CSWP, BSSE

http://www.engtran.com

http://www.niswug.org

"Node news is good news."

 

[IRstuff]

OK, clearly, FEA has improved since I last had much to do with it, but I still don't think that FEA is the tool for the job.

TTFN

FAQ731-376

 

[kellnerp]

You are still going to have to correlate the FEA with test data. Copper work hardens a lot. So I would suppose that you could get some idea of just how hard it might get as the blade progresses through. You might then correlate the hardness reached by the copper with the hardness of the blade material and then use FEA to vary the effect geometry plays.

My city library used to have an excellent book on cutting tool design written by a Japanese author. They chucked it after 911 with all the rest of their engineering library. You might look for papers on this subject in Google Scholar. Without some kind of theoretical underpinning you are just going to spin your wheels.

TOP
CSWP, BSSE

http://www.engtran.com

http://www.niswug.org

"Node news is good news."

 

[ngarwood]

If you haven't done so already, you should look at DEFORM-3D, particularly the machining toolkit:

http://www.wildeanalysis.co.uk/fea/software/deform/deform-3d-suite/machining

The website shows some really impressive images of simulated chip formation and the company claims their code can calculate tool life. I haven't used the software myself, so I can't say how much of this is reality vs. marketing hype.

 

[501560789]

thanks ngarwood i will check it