press fit question 3

[altnickee]

Dear Board members,

I have a rifle barrel (308 win ) witch need a larger diameter at the chamber area.
I was thinking of turning down the barrel diameter to 16 mm ( 0.62992 inch) and making a sleeve with a smaler inner diameter.

The sleeve would be 0.62992 inch inner diameter and 0.78740 inch outer diameter.

I would than put the barrel in the freezer (or cool it with dry ice) & heat the sleeve before assembly.

My question : how much difference in inner & outer diameter
would be necessary in order to get a good lock up ? at what temperature ?

All info welcome.

greetings,

Anthony

 

[GregLocock]

You need to use Lame's equation to find the interference pressure for a given interfernece and cylinder sizes.

Luckily someone put this together:

http://www.tribology-abc.com/sub1.htm

Which is a great piece of work



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[arto]

Look in ANSI B4.1 for shrink fits [in mach'y hdbk too]
Look up Autofrettage & thick walled cylinders.

What you have sound kinda thin

 

[Cockroach]

Wow, GregLocock! Great website with a tonne (metric) of information. Thanks.

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

 

[gearguru]

DIN 7190 "Pressverbaende" is the German standard for calculting press fit connections. It covers elastic, elastic/plastic, plastic deformations in the contact area and the presents the method (formulae) to determine when they occur.
Not an easy reading, but it covers the topic very good. I am not sure if there is the English version of it, though...

 

[stick1]

This is redundant, but another website that has a interference fit calculator is Engineer's Toolbox:

http://www.engineerstoolbox.com/

Go down the page to "ETBX on the web" for the Java applet access.