Flexural Kinematic Couplings For Rapid and Repeatable Positioning

Who to contact for more information:
Technical Licensing
Martin L. Culpepper Prof. Alex Slocum
617-258-8541 617-253-0012
mculpepp@mit.edu slocum@mit.edu

Developed as part of a cooperative research effort between: Naval Research Laboratory,   Ford Motor Company, and the MIT Precision Engineering Group

U.S. Patents:

5678944 : Flexural mount kinematic couplings and method
5769554 : Kinematic coupling method and system for aligning sand mold cores and the like and other soft objects and surfaces


What are they? Flexural Kinematic Couplings are a fundamentally new type of kinematic coupling.  They combine the repeatable location of traditional kinematic couplings with the stiffness characteristics of many other coupling methods.   They incorporate flexures or build in compliance to the kinematic members.   This is done so that the two components can be kinematically located (as in a traditional kinematic coupling) then brought together, as one would need for say casting molds.

kflex_mold_ex.gif (33915 bytes)

How they work After the kinematic members (3 "balls" and 3 "grooves") are mated, force is applied to bring the two components together. Parts of the kinematic coupling (flexures attached to one of the major components) displace and allow the components to mate, thereby creating a classical surface-to-surface, high load capacity joint. When properly designed, this can be accomplished without compromising the kinematic nature of the coupling.


kinflex_animation.gif (15608 bytes)
Flexure Built Into Groove

Performance It is difficult to give a concrete number for the repeatability of a kinematic coupling as this is dependant upon many factors:
  • Application
  • Load(s)
  • Sphere & groove materials
  • Sphere & groove dimensions
  • Others

However, the repeatability of kinematic couplings has been measured at 30 (not shown)- 400 minches.

kinflex_repeatabilities.gif (10159 bytes)

Applications Flexural kinematic couplings can be used in applications which require:
  • Repeatable location
  • High load capacity
  • Surface contact between components

Example applications include:

  • Casting
  • Molding
  • Die Sets
  • Sub-assemblies
  • Tooling & Fixturing

sheet_metal_gasket.gif (9704 bytes)

Example of Sheet Metal Gasket With Integral Sphere & Flexures