Non-contact speed sensors for watery environment 3

[edison123]

I want to measure the speeds of a rotating electromagnetic chuck and a rotating vertical grinder. Problem is that there is a continuous & copious flow of cooling media that covers the chuck and the grinding head with a resultant splash due to centrifugal forces.

The probe cannot be located very near the chuck or the grinding head. It should be at least 2 feet away due to physical constraints.

Any idea of non-contact speed sensors for this application ?

PS - If this is not the right forum for this post, please point me to the right one. Thanks.



Muthu

http://www.edison.co.in

 

[itsmoked]

This isn't a Blanchard is it?

Why aren't you just looking at the motor shaft?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[edison123]

Keith - How did you hit the bull so perfectly ?

Yes, it's Blanchard. The problem is that the client has Blanchard of all possible combinations - direct driven, gearbox driven with different gear ratios and topped by the fact all of them driven by VFD's.

The real people working with these machines absolutely have no clue on what the spindle speed is and are misguided by the VFD readings. So, there are productivity issues since the spindles are rotating at various speeds in different machines for the same job.

So, I would like to measure the speeds of the spindle as well as the chuck (which turns in opposite direction) to settle the productivity issues.

Muthu

http://www.edison.co.in

 

[ScottyUK]

Can you use a tacho or similar to establish true speed when the machine is not flooded with coolant and then scale the VFD analog repeater output into true RPM?



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[edison123]

Scotty - There is no place in the machine to fit a tacho. Also, the chuck speed (which is also VFD driven) has a role in the rate of material removal and has to be measured.

Are there any laser speed sensors out there ?

Muthu

http://www.edison.co.in

 

[itsmoked]

I happen to have a Blanchard magnetic chuck in the back of my truck I picked up today to test.




That is a hard one... Everything is so messy there. Fluids spattering everywhere.

I really think you need to try to do what Scotty suggested. Find a good repeater for your VFDs that let you set a scaling factor. Then use whatever it takes to measure the chuck and spindle and then just calibrate the repeaters. Label them with clear labels CHUCK & SPINDLE. That would solve your problem as far as workers knowing the actual speeds. This would also remove the cost and maintenance hassle any active measuring system would bring.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[edison123]

Thanks Keith and Scotty for that repeater idea. Any good suppliers for this item ? Will any off-the-shelf repeater be compatible with the existing drives (which are again of different OEM's) ?

Keith - My client also has a failed chuck of 42 inches dia. If you happen to have photos of this chuck in dismantled state, could you possibly upload them on the Internet and post a URL to them? Thanks.


Muthu

http://www.edison.co.in

 

[ScottyUK]

Muthu,

Depends on how much you are willing to spend. Most drives will give a 4-20mA output, and there are plenty scaleable indicators. I like the ones from BEKA Associates in the UK for use in harsh environments - robust and well-protected, but they are also quite pricey.


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If we learn from our mistakes I'm getting a great education!

 

[itsmoked]

I just have a 16" chuck and it's not yet in a disassembled state. The manual has pretty good cross section drawings.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Compositepro]

It doesn't sound like you need a continuous reading during production but want to be able to spot measure in different machines. A strobe light would work very well. You turn a knob to match frequency so the wheel appears motionless and read the meter.

 

[edison123]

Thx Scotty. The client has a plc wired operator's console, where certain machining parameters are shown. I have asked him to explore the possibility of exporting the VFD speed data to this console and display them after proper scaling.

Compositepro - Thx. That's what they are doing now. I wanted continuous speed display.

Muthu

http://www.edison.co.in

 

[itsmoked]

Edison123; I can.. but. I suspect that your chuck is too different than mine for the manual to be much help. My manual is for 16" and 24" chucks and even they are very different from each other.

Have you checked with Blanchard? I'm told they are very helpful and friendly. Could the manual be on-line?



Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

Can you put a magnetic tape on the rotating element anywhere? Balluff has a non-contact encoder system that can read a magnetic tape that I know can be ordered in lengths up to 48m.

Balluff BML Series pdf file


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[edison123]

Thanks Jeff. The client has already imported the VFD speed data into the operator's console with the correct scaling factor.

I will remember this mag tape for any future applications.

Muthu

http://www.edison.co.in