solid flange coupling dimension allowances 1

[chumet1]

attached is a coupling and shaft layout. the coupling with initial ID of 80mm was bored out to 100mm to suit the shaft diameter of 100mm. the shaft was inserted into the coupling up to 140mm to allow for sprocket alignment at the other end of the shaft. my question is: is there a standard minimum amount of coupling hub material labelled Y on the diagram that is required to be left for an effectively strong coupling-shaft fit, with respect to shaft diameter. and also the standard minimum contact length between shaft and coupling with respect to shaft diameter...
thank you

 

[racookpe1978]

To avoid the very-real threat of attached viruses with a .docx file, few engineers will open such a Word document.

It will probably be better to submit a pdf or gif or jpg image-only file.

 

[desertfox]

Hi
What you need to do is calculate the stresses on our shaft and hub gnerated by the interference fit btween the mating parts.
The interference fit is detrmined by the torque you want to transmit.
So I don't think there is a standard as such the wall thicknss of the hub is based on the stresses as mentioned above.
Try this site for some information.

http://roymechx.co.uk/Useful_Tables/Mechanics/Cylinders.html#Interference

 

[chumet1]

racookpe1978 noted, ive reattached the drawing in pdf

 

[jlnsol]

There seem to be a standard like this for couplings with bolts connection;
D hub = 2 x D shaft
D pitch cirkel bolts = 3 x D shaft
D flange outside diameter 4 x D shaft

 

[Tmoose]

I'd be equally concerned with issues of controlling runout of components and aligning the coupled components. Rigid/flange couplings are unforgiving devices.

Similar to fit concerns mentioned by others API would expect at least a few 0.001s inches interference and a key as standard.
A rigid coupling is likely to doggedly wiggle and taunt a slip fit hub. Problems with loosening and fretting are right around the corner.

Coupling catalogs often list "max permissible bore" for various hubs with full or custom low profile keys. And minimum engagements

 

[Cockroach]

Well, you need to consider many things in order to answer the question.

Clearly the contact length will depend on the load you are trying to hold, plus an uncertainty allowance. Since you have the the shaft diameters so well defined, the axial force require for the force fit will govern the size of press you need. I suggest using one of the website canned programs to come up with this calculated result, which will dictate torque holding power.

On the other hand, you could have a shrink fit. This is much easier to do and requires nothing more than a heating source. I prefer to use a welding torch and heat up the hub in a uniform matter. Upon cooling, it shrinks back to the original size and holds the shaft. This means there is little mechanical deformation as you would have for the mechanical fit using a press, and thus, no real equipment requirements. Still the same computation however, you need to determine the length the shaft of OD would sit inside the flange of ID in order to hold a prescribed torque.

My guess is that you want an FM3 fit, something along the order of 0.0004/0.0007 inches of interference at the mating interface.

Regards,
Cockroach

 

[chumet1]

this job was a breakdown scenario and was done presuming that the shaft diameter met the required torque and load, calculations which were done to come up with the size of the shaft. key sizing and interference considerations were also done with respect to shaft size i.e 1" square key and 0.01mm interference for a 100mm shaft. however because the hub had to be bored out from its original ID my concern was what is the tolerance hub thickness for a given shaft diameter. this, i believe should come as a standard like what was given by jlnsol, just like how you come up with a standard key size for a 100mm shaft.

 

[dvd]

Key size, like hub diameter, depends on the material used. The hub standard using diameters may or may not keep you out of trouble.

 

[desertfox]

Hi
I might of helped if you had given all the information you have just given in your initial post, then people would have known all the calculations etc was already done.