rõngavaltsimine, rõngaringvenitus
mahtvormimise protsess/-operatsioon avaga toorikutest rõngakujuliste toodete ja toorikute tootmiseks (valtsimiseks) rõngavaltspinkidel, the process of shaping weldless rings from pierced discs or shaping thick-wall ring-shaped blanks between rolls that control wall thickness, ring diameter, height, and contour
