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BrianGar (Automotive)
7 May 10 9:02
I have a problem. I need to lock an oil pump rotor to a shaft. Rotor is of the normal design and is driven via the through shaft. This in turn drives the second meshing rotor as can be seen in many oil pumps over the years.
The Rotor is hardened steel and has been taken from an oem oil pump. In the original pump the rotor was an interference fit onto its driver shaft. The new shaft it now sits on has to have a clearance fit for other design reasons. So I need to know how Ill go about locking the rotor to my new driven shaft given that its a clearance fit. The shaft is 14mm in diameter and the rotor approx 30mm in diameter. The pump is NOT a pressure pump but a scavenge pump, so the only pressure the pump will see is the head height to oil tank from sump,and I suppose accelerating/decelerating torsion at the point of clearance fit(hardly any to worry about at that diameter)
As for the clearance fit tolerance Im not too sure as yet, but its a snug fit and can be slid onto shaft by hand and will stay there if held vertically. Rotor material is nothing fancy, plain old oem rotors, shafting is 316 stainless. 字串2
Should I bore the rotor and fit a spring pin? Could be hard to bore and I may have to remove hardness and re-quench to drill(dont really want to do that)
Or> I have been onto a few 'famous' chemical bond companies and they assure me that there products will work, or at least, the data sheets says they will. I need convincing, 'glueing' a rotor onto a shaft scares me a little. Operating temp is at a guess -5 to 140c.
Any help folks? Convince me that chemicals will work, or not.
Thanks in advance, Brian.
desertfox (Mechanical)
7 May 10 10:56
Hi BrianGar
What is the bore of the rotor or do you mean its a 30mm bore?
Assuming the clearence isn't that great what about a keyway.
desertfox
BrianGar (Automotive)
7 May 10 13:07
Sorry, bore for shaft is 14mm, o/a diameter of rotor is exactly 32.5mm. The teeth on rotor are 6mm high which leaves me with around 4 mm between base of teeth and bore. 字串1
I had thought of a key and I guess it would not need to be that deep into rotor but Im worried about broaching, will a normal arbor style saw tooth broach cut the rotor without relieving the heat treatment first?
Thanks for the reply.
Brian.
desertfox (Mechanical)
7 May 10 13:52
Hi BrianGar
Not sure whether the broach would cut or not, what about sleeving the bore using an intereference fit and then boring the sleeve to interference fit with the shaft, if your torques are low it might work.
desertfox
BrianGar (Automotive)
7 May 10 14:24
Ya, good idea actually. Have you anything against pinning it? Just wondering? Ignoring the hardness/drilling for a second.
Thanks again,
desertfox (Mechanical)
7 May 10 14:28
字串9
Hi
Well pinning might work, but doing it the way I said in my last post you won't need to machine the rotor.
desertfox
BrianGar (Automotive)
7 May 10 14:39
True, but Id them have to machine shaft, Ill sleep on it,
Many thanks for your replies, Im very grateful.
desertfox (Mechanical)
7 May 10 15:16
Hi Brian
Your welcome, why would you need to machine the shaft?
measure the shaft before you start, so machine the sleeve and force fit, then force fit the shaft after.
desertfox
BrianGar (Automotive)
7 May 10 15:25
You mean the sleeve would be just a hair thick to move from clearance fit to interference fit? Wow! Thats uber thin, or have I it taken up wrong?!
字串8
desertfox (Mechanical)
7 May 10 15:28
Hi Brian
No you got it right and I got it wrong, yes your going to have to machine the shaft sorry!
desertfox
MintJulep (Mechanical)
7 May 10 16:06
How about brazing?
plasgears (Mechanical)
11 May 10 12:56
We had a heavy duty ice crusher gear that was pressed onto the shaft like a broaching operation. The gear was PM HT, and it had a coarse semicircle spline bore. There were about 8-12 teeth. It broached an intimate connection on the shaft. It sustained shock loading in operation. Highly recommended.
patprimmer (Publican)
7 Jun 10 22:38
If you do cut a keyway make sure it is cut under the thick part of the tooth profile. 字串7
Maybe spark eroding might be feasible if the gear is so hard that a tungsten carbide tool won't cut it. Regards
Pat
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BrianGar (Automotive)
8 Jun 10 8:25
Pat'een, got it sorted, mounted the rotor in the tool post of lathe and fitted a 3mm carbide burr to chuck, advanced it with rpm set at the maximum, 5 passes and I had myself a semicircular groove cut, Im very happy with the result as this will also allow a bit of axial float between the rotors and shaft which is what I need for assembly/expansion of shaft etc. My broaching cutters wouldn't even mark the rotors and removing heat treat, broaching, re-treating wasn't really an option as they would surely shift dimensionally during that process, as you know.
Thanks to all. 字串6
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