clamping force

[craigwinters]

hi all

how much clamping pressure is there when a 1" whitworth is torqued to a certain number? does it vary depending what type of thread is used? is there a formula that can be used to fidure out the clamping pressure?

 

[KENAT]

faq725-536 gives information for metric thread form. Should at least give you an idea what you're looking for. I suspect a decent internet search would turn it up but I could be wrong.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[KENAT]

thread725-22078

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[Cockroach]

CraigWinters....
You must also include the SolidWorks sub assembly components with the SLDASM file. Otherwise you're prompted for these external components, which we have no access to, and the model crashes. Next time, pdf the assembly and insert it in the same manner.

To answer your question, the clamp force is simply twice the torque applied to the screw divided by pitch diameter of the thread. This would be equivalent to the axial force induced by torque by threading.

There would be a slight variance in clamp force between relative thread geometries because pitch diameters are not all the same. For a 1.000 nominal stub acme thread for example, the clamp force would be roughly the same as a 1.000 UNC or 1.000 Acme thread since pitch diameters lie relatively close to eachother, but not equal. We're talking very small percentages here, not large departures in values. What does vary greatly is the shear area of the threading between differing geometries of identical nominal diameter. So the stresses would vary according to thread specification, the primary reason for analysis and selection.

But I leave this point to be proven by the reader.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[MartinSr00]

Mark's Handbook has a formula of bolting force. In my ninth editio, it's in the chapter on friction of machine elements/Screws with V Threads. p. 3-30 in my 9th Edition.

 

[Pud]

Whitworth???

Are you rebuilding the Ark?

http://www.tynevalleyplastics.co.uk