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Member
vinay.warrier
Posts: 4
Registered: ‎06-20-2008
Message 1 of 4 (265 Views)

Help regarding screw joints in assembly

265 Views, 3 Replies
07-02-2008 10:18 PM
I have created an assembly in which a screw rod and a internally threaded hollow cylinder1 form a screw joint. I want to give an angular velocity to the screw rod and get the linear motion out of the cylinder1. The screw rod - hollow cylinder1 arrangement is inside another hollow cylinder2 which moves with respect to a grounded base. I created an Insert constraint for the screw rod and cylinder2. Also for screw rod and cylinder1. When I switch to dynamic simulation, the screw rod and cylinder2 turn into a welded group, thus disabling me from giving an angular velocity to the screw rod. PLEASE HELP.
*u2
Message 2 of 4 (265 Views)

Re: Help regarding screw joints in assembly

07-02-2008 10:44 PM in reply to: vinay.warrier
wrote in message news:5972482@discussion.autodesk.com...
I have created an assembly in which a screw rod and a internally threaded
hollow cylinder1 form a screw joint. I want to give an angular velocity to
the screw rod and get the linear motion out of the cylinder1. The screw
rod - hollow cylinder1 arrangement is inside another hollow cylinder2 which
moves with respect to a grounded base. I created an Insert constraint for
the screw rod and cylinder2. Also for screw rod and cylinder1. When I switch
to dynamic simulation, the screw rod and cylinder2 turn into a welded group,
thus disabling me from giving an angular velocity to the screw rod. PLEASE
HELP.


Well, I'm screwed on this one............
Distinguished Contributor
Josh_Petitt
Posts: 5,400
Registered: ‎09-21-2004
Message 3 of 4 (265 Views)

Re: Help regarding screw joints in assembly

07-03-2008 12:53 PM in reply to: vinay.warrier
post your zipped assembly and parts, someone will show you how.
Active Contributor
gerard.saignavong
Posts: 34
Registered: ‎05-02-2006
Message 4 of 4 (265 Views)

Re: Help regarding screw joints in assembly

07-07-2008 06:57 AM in reply to: vinay.warrier
Hi,

If your parts belong to a welded group in Dynamic Simulation, it means that your parts are symmetrical and rotational degree of freedom has been considered as useless.

in Dynamic Simulation, to extract your screw from the welded group, RMB on the part to display contextual menu and select Retain DOF. This command will enable the degree of freedom.

However, I believe that an mate constraint between the screw rod and the cylinder would be better instead of a insert constraint. In Dynamic Simulation, a translational degree of freedom is needed for a screw joint.

I attached an basic example.

Hope it helps,
Gerard
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