Kozzy

Grossly ignorant on induction heaters but....

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Long ago I looked into an induction heater for one of our commercial processes and at that time (the stone age) the cost was as much as a new Lexus.  The maker at that time said it had to be high-freq and in those days electronic switching was $$$$.   I see now that there are affordable Chinese versions out and even some home-mades so that got me thinking about the possibility again.

Currently we resistance heat the part--it's hard to control and every little glitch can cause inconsistency.  What we have is a 3/16" dia. round bar in T304 that sticks about 3/8" out of an assembly (could be more if needed). The machines uses an air cylinder to move a ram/electrode against the end of the bar, resistance heats (calculates at about 3000 amps at 2 volts) the bar in about 5 seconds, the pressure is turned up and the of the T304 flattened like a rivet head.  unfortunately, the old controls are all time based, not heat based so if the contact isn't perfect due to the sheared end of the 3/16 bar or scale on the electrode, it might just crack the part due to underheat.

Just wondering if anyone who has more knowledge about induction has any ideas or comments.  Ideally,  I'd like to induction heat, detect the forging temp electronically (can that be done through an optical fiber based on light/color?) and then just press when ready.

We're talking numbers in the thousands.  Happy to sacrifice speed for consistency because re-working the bad ones costs way too much time and material.

I'm completely ignorant on the subject so just fishing for knowledge and ideas...Didn't even know that Induction had some into the realm of affordable to try until I stumbled across the forum examples.

Thanks for anything you can offer.

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From your description, why not improve consistency of your existing process by squaring up the sheared end of the bar with an angle sander or linisher?

Alan

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From my understanding, you should be able to work your metal, successfully across a wide range of temperatures. Put a near perfect piece of steel in the coils and note the time it takes to get it to the high forging temperature. If you run them at this time interval then hopefully, you will still get the less than perfect pieces to the lower forging temperature or above.

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What you want is very do-able with induction, and quite inexpensively too, my 18kw would do 3/16" in seconds so I don't think you'll even have a timing issue. However with such a short "stick out" you might have an issue with heating the adjoining parts(but then I don't know about the how/what?) with my sort of set-up you'll be in for about $2k quite inexpensive really.

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Thanks, all.

Answering a few questions---

The rods are actually coiled wire that's straightened and cut in a rotary straightener.  Even if the ends were made perfectly square, the electrode itself becomes a bit uneven under the arcing and introduces it's own inconsistencies.  It should be electronically switched but isn't..100% on time for the high current.  I tried to get the maker to do it differently but wasn't in a position to have enough input.

The short "stick out" is a problem but I can change the rod clamping on a revised machine to compensate for that.  

There are some other shortcomings also...should have had better shielding gas flow for instance.

Just because people were kind enough to give opinions and the day is boring, here's a photo of the existing "problem" machine that I want to bring from the stone age to at least this century. This was during the original testing so things are still in "unfinished" mode.

header.thumb.jpg.daf1025fe4e474ea587b8d1

 

 

 

 

Edited by Kozzy

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