Method of reaction injection molding a valve

Abstract

A mold and method of forming a butterfly valve and the novel valve formed. The concept includes providing a valve skeleton having a body portion, a hollow neck extending from the body portion to receive a valve stem and a cruciform-shaped actuator plate portion on the hollow neck, suspending the valve skeleton in a mold cavity in inverted orientation, and injecting reaction injection molding polymer by laminar flow into the bottom of the mold cavity with an amount of polymer sufficient to fill the space from the bottom up, encapsulating the skeleton, and overfill the space to force the leading edge of the polymer out the top of said space into said escape chamber to entrap residual gases into a severable offal member. The polymer encapsulates the cruciform-shaped actuator plate while filling the corner spaces thereof, except for fastener orifices which form adjacent the cruciform legs. A gate at the bottom of the mold assures laminar flow of polymer into the mold cavity. The valve skeleton may have a plurality of radially extending mounting leg portions fitting into lug-receiving cavities of the mold including at least one mounting lug-receiving cavity projecting radially outwardly and upwardly, the mold cavity including an upwardly oriented flow passage up from said at least one lug-receiving cavity to the polymer-receiving escape chamber, for flow of air from the at least one lug-receiving cavity through the flow passage to the escape chamber.