Vulcanizer lock means

Abstract

Vulcanizer lock means for a vulcanizer of the type wherein a tire carcass is shaped and cured in a mold cavity defined between top and bottom mold sections which are respectively mounted on a vertically movable support member and a fixed support member characterized in the provision of a mold-embracing lock ring which at its lower end has a rotatable, but axially fixed, connection with said fixed support member and which at its upper end has radially inwardly extending lugs with bottom helical surfaces engaged with top helical surfaces of radially outwardly extending lugs of said movable support member when said lock ring is rotated to locking position, said lugs being circumferentially offset when said lock ring is rotated to unlocking position to permit vertical movement of said movable support member and top mold section for unloading of the cured tire and for loading of the next uncured carcass. The vulcanizer lock means is further characterized in that means for rotating the lock ring to locking position is effective merely to bring the helical lug surfaces into mating contact without preloading, the modulus of elasticity and cross section area of the lock ring being such that, upon application of vulcanizing pressure within the tire carcass in the mold cavity, the elastic elongation of the lock ring maintains mold separation within predetermined permissible flash limits. To minimize the force requirements for rotating the lock ring to and from locking position, it is rotatably supported by bearings on said fixed support member. Furthermore, the helix angle of the interengaged lug surfaces is less than the angle of friction so that mold separating force does not impose a torque load on the lock ring in unlocking direction.