Matrix assembly with segmented matrices

Claim 1

A matrix assembly for use in treading tires, said matrix assembly comprising cooperating axially separable matrix shell halves, a matrix half carried by each matrix shell half, said matrix assembly having an axis about which said matrix shell halves and said matrix halves are generally centered, each matrix half and its respective matrix shell half having first cooperating seating surfaces engageable in a plane extending generally transverse to said axis and second cooperating seating surfaces extending generally circumferentially around said axis and disposed at a converging angle To said axis, each matrix half being formed of a plurality of segments separately movable within and relative to the respective matrix shell half in a combined axial and circumferential direction from its seated position to a matrix expanding position for the release of a treaded tire and the reception of a tire to be treaded, a pair of guide pins carried by each matrix shell half mounting each respective matrix segment for guided retained movement between said seated position and said matrix expanding position, said matrix segments being formed of a relatively soft heat conducting metal, and wear retarding means for retarding wearing of said matrix segments during the movement of said matrix segments, said wear retarding means including said guide pins of each matrix segment being parallel and lying in a plane disposed at an angle to said axis generally equal to but slightly less than said angle of said second seating surfaces whereby as said matrix segments move to separate said first seating surfaces said matrix segment second seating surfaces move circumferentially inwardly away from the respective matrix shell half second seating surface and thereby prevent wearing of said second seating surfaces.