Lead Screw model in Creo and calculations

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SUMMARY

The discussion focuses on creating a lead screw model in Creo for moving a 400lb load. The user determined that a lead screw with a major diameter of 1 1/4 inches and a thread pitch of 4 TPI requires approximately 36.70 lb-in of torque to move the load. The user successfully established a relationship between RPM and linear velocity but sought guidance on analyzing the fail conditions of the L-shaped support for the lead screw. The recommendation was to perform stress analysis in ANSYS Workbench instead of Creo to assess the structural integrity under applied forces.

PREREQUISITES
  • Understanding of lead screw mechanics and specifications
  • Familiarity with Creo for 3D modeling
  • Knowledge of torque calculations and linear motion principles
  • Experience with finite element analysis (FEA) tools, specifically ANSYS Workbench
NEXT STEPS
  • Research lead screw design parameters, focusing on pitch and torque calculations
  • Learn about stress analysis techniques in ANSYS Workbench
  • Explore the relationship between RPM and linear velocity in mechanical systems
  • Investigate common failure modes in structural supports under axial loads
USEFUL FOR

Mechanical engineers, CAD designers, and anyone involved in the design and analysis of mechanical systems using lead screws and structural supports.

inamukak
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Hi

I'm trying to make a lead screw in Creo which would be used to move a 400lb load linearly along the ground. This would be turned manually using a lever as shown in the pic (not the complete model). I have used a lead screw with a major diameter of 1 1/4 and determined the torque to move the load would be around 36.70 lb-in. What I'm unable to determine is the speed at which this would move the load a total distance of 3 feet, and if it would be possible to change this speed so that the lever doesn't have to be turned for quite a lot of time. Any help would be appreciated.

Thanks in advance!
 

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Welcome to the PF.
The diameter of the lead screw is not the important parameter, you need to specify the pitch of the screw thread.
That will tell you how far the load will move for each turn of the crank handle, (your lever).
The speed you turn the crank will decide the speed the load moves.
 
Hi

Thanks for the reply. I took a TPI of 4 and etermined the torque required to move the load. I was basically looking for a way to related the RPM and the linear velocity, which I have figured out now.
Also, I'm trying to determine the fail conditions for the L-shaped support holding the lead screw and the lever, but I have no clue where to start. I've been trying to run simulations in Creo to determine this but to no avail. What stresses and strains should I take into consideration? And how will a force or torque on the lever lead to failure of the support?

Thanks!
 
If you assume the base plate is firmly attached, then only the vertical part of the mount will deflect when an axial force is applied by the lead screw. That will bend the material that is between the base and the lead screw. When the material bends the screw will be misaligned in the thread which will have other implications.
 
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Thanks for the answer! I decided to perform the analysis in Workbench instead of in Creo and did manage to get some results from your answer.

Thanks again!
 

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