Press fit pin retention

[MattRR]

We currently pin two concentric shafts to form a torquemeter. We use five pins around the circumference of the shafts. The pins are inserted radially from the outside. We weld over the tops of the pins to insure they do not come loose under heavy vibration. We would like to eliminate the weld. Is it possible to just use a heavy press fit? Do we need to stake or swage the pin? Is there s special type of pin we should be using?
Also, we machine a flat on one side of the pins. The purpose is to allow air to escape during the pressing operation, as the inside shaft is not drilled all the way through. Is this common practice? Is it really necessary?

Thanks for any help you can provide!
Matt

 

[unclesyd]

ry the following:

http://www.groov-pin.com/products.htm

http://www.spirol.com

Both of these people make groved solid pins that are extrememly resistant to vibration. They have good design information.

Why do you have vibration?

 

[MattRR]

We have vibration under unusual situations - usually when we have not balanced the assembly correctly. Thanks for the websites!

 

[wic43]

i advise you to use the spring pin and slight press fit.

thanks,wic43

 

[ornerynorsk]

You cannot rely on press fit only if you need failsafe under vibration conditions. Some sort of mechanical fastening must be used.

 

[MattRR]

Would loctite be ok?

 

[unclesyd]

I haven't been able to get "Locktite" to go into a pressed fit hole very well with modification of the hole.
If you look at the grooved pin you can see that it is a mechanical fit because of the upset groove.

Also you can double spring pins to help both in the load carrying capacity and stay at home properties.

Our use for the groove pins were in drive shafts going around 100 RPM with a single Cardan u-joint and one end free.

 

[MattRR]

If we put a flat on the side of the pin to let the air out, would loctite work ok? There is a loctite UK website that indicates loctite works well on press fit pins.
I know that roll pins do work lose. I just need assurance that the groove pin absolutely will not work lose before I can propose it. We are turning 15000 rpm on a 4 inch diameter. Thanks for all the help and info! If anyone else has an opinion on locktite or groove pins, it would be greatly appreciated!

 

[unclesyd]

I still would check with say Grov-pin/Spirol engineering because they are suppose to take hihg vibration and require high pull out forces.

If this is still a problem try the following site concerning the Polygon Drive. It was used on a lot of our high speed

http://www.jobshop.com/techinfo/papers/grinding2.shtml

I never like grind a flat on a sold unless it was absolutely necessary.

 

[unclesyd]

Here is all the URL ofr the Ployegon Drive

http://www.jobshop.com/techinfo/papers/grinding2.shtml

 

[CADShark]

There is another company you could check out.

http://www.driv-lok.com

Do you have any high heat situations? Because some loctites are not the best under heated conditions. Check out their website

http://www.loctite.com

for more info.