They are expanded, at the most basic, by putting a flat washer across the flange on the outside ,
and a greased bolt in them
same 5x.8 . and tightening the bolt
others have used a QR from a Seatpost, or hub put thru a tube
Spare axle with the cone and locknuts , perhaps ..
and just closing the QR to Pull the Riv nut thread against the outside flange..