Mobile Hot Cell Fixture Tool

Project Description

Problem Description and Motivation

• Needed to manipulate a 6000 lb. teletherapy head in all six axes
• Sources in teletherapy heads present a national security risk for many countries across the globe the fixture assists in collecting discarded sources
• The main constraints included the ability to withstand at least a 6000 lb. load and a roughly 13 in height clearance

Design Descripton

• Turntable provides horizontal rotation
• Three jack screws provide vertical rotation and translation
• Ball screws, linear rails, and ball bearings under the base plate provide horizontal translation

Performance Review

• Built a full-scale model to test range of motion
• Used manufacturer's specifications
• Performed FEA and load analysis on all major load bearing systems

Conclusion

• Finite element analysis shows that the structure should hold expected loads
• The physical model demonstrates movement in all intended directions and any swinging motion in the hanging plate will damp out very quickly
• Lessons Learned:
  • Using ball rollers instead of multi-layered tracks simplifies design and holds loads better
  • Using cut sheet/plate materials instead of machined blocks reduces cost significantly
  • Positioning loads directly over supports vastly reduces structural strength requirements
• Recommended Future Work:
  • Consider adding motorized controls for easier operation
  • Develop preventative maintenance procedures to help ensure reliable operation
  • Add failsafe mechanisms to mitigate the consequences of material failure