Testbed for verifying production gearing components 1

[geesamand]

I am proposing a design for a testbed for verifying the performance of gearing that goes into our production gear reducers. I'm soliciting for ideas on a few parts of the design. (I figure the gear/pulley specialists may have very relevant experience here).

1) I need to mount the production pinion shafts and gears together on bearings. Due to the wide variety of bearings used in the production drives, I am leaning toward using an oversized standard bearing in the testbed as opposed to the smaller bearings that the shaft ends are designed for. I am considering attaching a short shaft stub on each end of the gear shafts. The stub will have a journal on one end for the bearing and a female socket on the other that fits over the bearing journal on the shaft and is clamped tightly. The torque load will obviously be minimal but I need a rigid, well-aligned, and compact connection on the female end of the stub. What kind of shaft clamp might perform well? Will a taperlock or QD bushing provide the running accuracy to keep runout around .0005" TIR maximum?

2) I'd like to incorporate a torque transducer (wireless?) that will allow us to read the torque load being applied. I don't think I need more than 5% accuracy but I will need a very wide range of measuring capability. I believe the technology is out there but I haven't found a vendor yet. If you have a pointer to a particular supplier that will help immensely.

David

 

[tbuelna]

geesamand,

When you state that you wish to "verify the performance of gearing", just what precisely is it about the gearing that you wish to verify? Noise? Efficiency? Fatigue life? The design of your test rig can vary depending upon what characteristic you wish to measure.

The most basic advice I would give you when designing a gearbox test rig is to remember that a gearbox is a system of components, and the performance of each component has an effect on the others. For example, the stiffness of the bearings and housings can have a big effect on the gear tooth contacts.

If you're going to design a dedicated test fixture for specific gear sets, it would be wise to duplicate the characteristics of the production housing and bearings as closely as possible.

Hope that helps.
Terry

 

[geesamand]

We will observe contact / noise / vibration under load. The tests won't last very long I expect, a couple of hours for these characteristics to stabilize.

Obviously, different bearing centers will have an effect on things and that's why I'd like the stub ends to extend shaft length by about an inch per side on a 6" shaft. The stub end concept will be faster and cheaper to configure, compared to pressing on a set of production bearings that will consume a set of bearings for each test and require the use of bearing heaters and/or a press. This drivetrain has a maximum shaft speed of 1800rpm so I feel harmonics and deflections should not be an issue. Haven't yet decided which way this will end up going as both configurations have their benefits.

 

[Strong]

Take a look at strain-telemetry torque system at

http://www.binsfeld.com.

It works well for both test stand and field applications. I have a system from them, but I don't represent them.

Take a look at magnetic shaft coupling with variable speed capability at

http://www.fluxdrive.com.

It would completely isolate torsional vibrations from the motor drive. There are a lot of benefits of the magnetic drive including low sound and vibrations and misalignment tolerant, if the available torque/power rating fits your test stand.

Walt

 

[MikeyP]

The noise performance will vary significantly with the misalignment of the gears that occurs in the real gearbox due to shaft, bearing and housing deflection. At the very least you should design in to your test rig the capability to misalign the gears to cover the range of possible misalignments in the real gearbox.

Bearing stiffness (which varies with load and misalignment) also plays a big role in how well the vibration is transferred to the housing so make sure your bearing fits and bore alignment is tightly toleranced.

You will also have to have a fool-proof way of mounting the gears consistently if you are going to be taking them on and off all the time. You need to be sure that if you measure a gear pair, take them off then put them back on and re-measure that you are getting the same results.

M

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Dr Michael F Platten