Lead Screw model in Creo and calculations

AI Thread Summary
A lead screw model is being developed in Creo to move a 400lb load manually. The user calculated a torque of 36.70 lb-in with a lead screw diameter of 1 1/4 and a TPI of 4, successfully relating RPM to linear velocity. The discussion highlights the importance of specifying the screw thread pitch for determining load movement per crank turn. Concerns about the structural integrity of the L-shaped support holding the lead screw and lever were raised, focusing on stresses and potential failure conditions. The user shifted to using Workbench for analysis after initial challenges in Creo, achieving better results.
inamukak
Messages
7
Reaction score
2
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!
 

Attachments

  • lead screw.PNG
    lead screw.PNG
    19.2 KB · Views: 658
Engineering news on Phys.org
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.
 
  • Like
Likes 1 person
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!
 
Posted June 2024 - 15 years after starting this class. I have learned a whole lot. To get to the short course on making your stock car, late model, hobby stock E-mod handle, look at the index below. Read all posts on Roll Center, Jacking effect and Why does car drive straight to the wall when I gas it? Also read You really have two race cars. This will cover 90% of problems you have. Simply put, the car pushes going in and is loose coming out. You do not have enuff downforce on the right...
Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'
Scenario 1 (figure 1) A continuous loop of elastic material is stretched around two metal bars. The top bar is attached to a load cell that reads force. The lower bar can be moved downwards to stretch the elastic material. The lower bar is moved downwards until the two bars are 1190mm apart, stretching the elastic material. The bars are 5mm thick, so the total internal loop length is 1200mm (1190mm + 5mm + 5mm). At this level of stretch, the load cell reads 45N tensile force. Key numbers...
I'm trying to decide what size and type of galvanized steel I need for 2 cantilever extensions. The cantilever is 5 ft. The space between the two cantilever arms is a 17 ft Gap the center 7 ft of the 17 ft Gap we'll need to Bear approximately 17,000 lb spread evenly from the front of the cantilever to the back of the cantilever over 5 ft. I will put support beams across these cantilever arms to support the load evenly
Back
Top