Measuring rotating Force
Measuring rotating Force
(OP)
I am attempting to build a machine to hone the cylinders of a automobile engine. I need to be able to measure the force required to hone that cylinder. I want to be able to measure the force as it travels up and down in each cylinder so that I can determine the tight spot. I tried to measure in amps and watts but I am driving thru a gear box and that measurement has not been adequate. any help here would be great as I have run out of ideas





RE: Measuring rotating Force
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Measuring rotating Force
You would need slip rings to bring in power for the preamp rotating with the head, and either more slip rings or an RF link to get the buffered data off the rotating assembly for analysis. For the purpose of locating the hard spots, you'd also need a linear transducer on the ram and an angular position transducer on the rotating assembly. You could do it easily for a hundred grand, and maybe for ten grand with some creativity, less if you're willing to homebrew a lot of stuff and learn a lot of new skills and spend a lot of time doing it.
I'm guessing it's all been done before, but the answers have commercial value, so the guys who know them probably aren't talking.
Or you could start at sae.org, and search for appropriate research papers in their mountain of mud. Bring your wallet.
If your labor is worth anything, it would be cheaper to buy a commercial honing machine, or contract the services of someone who has already done so.
Mike Halloran
Pembroke Pines, FL, USA
RE: Measuring rotating Force
Pat:Since I do have a Dynomometer, your thoughts is one that I have considered, but we are talking low ft. lbs measurement and I could not figure out how to load the shaft to get a deflection
RE: Measuring rotating Force
Have an arm coming off this so it rests against a stop. Put a load cell between the arm and the stop.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Measuring rotating Force
RE: Measuring rotating Force
RE: Measuring rotating Force
RE: Measuring rotating Force
Also if you had a long timing mark along the whole shaft so it stayed visible throughout the range of axial travel.
I could also see patprimmers concept working pretty well.
RE: Measuring rotating Force
The basic idea is usually some type of torsion bar with rotary encoders at each end.
As more torque is applied, one end lags the other, and you get a variable duty cycle digital output proportional to torque.
RE: Measuring rotating Force
racear
RE: Measuring rotating Force
RE: Measuring rotating Force
racear
RE: Measuring rotating Force
The internal inertia of the fast spinning drive motor, and friction in the transmission, will mask small cyclic torque fluctuation in the output shaft. The motor current will be very insensitive to the indication you are seeking.
A further thought has occurred to me.
How about using a very flexible toothed drive belt, and measuring belt tension on the drive side.
The belt could be wrapped around a spring loaded idler, spring deflection would indicate load torque.
It's a bit Mickey Mouse, but at the low speeds involved, it should work if the hone only has to turn in one direction.
RE: Measuring rotating Force
A power transducer measures the input power to the motor and is a much better indicator of motor load. It could be a solution if the motor actually does see the load variations. Here is an example;
http://www.crmagnetics.com/products/Power-C8.aspx
You have to decide if "250 ms max. 0-90% FS" is fast enough (the response time is 0.25 seconds to change from 0 load to 90% load) and also look at finding a meter to read that output with a quick response.
RE: Measuring rotating Force
racear
RE: Measuring rotating Force
Now for next phase, I need to monitor how much (in size0 I am removing from the cylinder bore. I really dont care about size, I just want to know how much I removed while I honed. Remember we are floating in coolant. Please bounce some ideas.
racear