It is a disk cam mechanism of translation follower.
Turn grey disk cam to open or close the aperture.
Fixed green disk has a hexagon slot.
Each blade (follower) slides along one side of the hexagon.
Inventor files of this video:
http://www.mediafire.com/file/k39ns41rkqebx93/DiaShutter5aInv.zip
The mechanism can be used for control valves:
https://www.youtube.com/watch?v=3w7SSUFHjWE
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