Help with sliding mechanism

[solid7]

I have a mechanism that I don't quite know how to classify. Basically, it's a dowel pin that actuates sliding motion by riding into (forcing against) a slot in a plate. The sliding pieces move parallel to the handle of the mechanism. The handle contains the dowel pin which actuate the sliding pieces. So, I have a pin with radial motion, and plates with straight (resultant) translation.

The slot that the pin slides in is also a "V" shape. What I want to know is, how do I optimize the angle of the slot to prevent binding during actuation?

I wish that I could provide pictures, but the firewall has blacklisted photosharing sites.

Thanks in advance.

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Catia Design|Catia Design News|Catia V5 blog

 

[handleman]

Can you attach the pictures using the "...or upload your file to ENGINEERING.com" link below?

-handleman, CSWP (The new, easy test)

 

[eromlignod]

Sounds like a scotch yoke.

Don
Kansas City

 

[solid7]

Yes, I would say that it is a modified scotch yoke. Rather than the straight slot, it is a "V" shaped slot.

We currently have a prototype built, but the slot angle is too aggressive, and creates a binding condition. How do we calculate the correct angle? We designed around travel of around 1/4" - 5/16". The mechanism works when it is impacted, but we are looking for smooth operation.

Thank you.

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Catia Design|Catia Design News|Catia V5 blog

 

[eromlignod]

Do you have room to use a cam follower instead of just a dowel pin? This might reduce your friction enough to keep your present angle.

Don
Kansas City

 

[hydtools]

You might consider calculating with your loads and use the material's coefficient of friction. When the angle creates a condition where the friction force is nearly your applied force, the surfaces will not slide. Or will begin to 'bind'.

Ted

 

[vc66]

Offset the central axis of the radial dowel pin from the center of the parallel motion by some amount in the x-direction. This prevents having no y-component of force in the top and bottom dead centers. That should prevent the binding.

V

 

[chicopee]

If it is a scotch yoke, the "V" groove would tend to cause some backlash--wouldn't it?