Method and apparatus for applying a foamable resin

摘要

A method and apparatus for dispensing multi-component foamable fluid plastic materials such as polyurethane foams. The apparatus includes a mixing chamber defined by an axial passage in a support body structure. The mixing chamber receives reactant fluids for mixing then allows the fluids to exit through an opening at one end of the axial passage. Two fluid inlet openings in a wall of the axial passage admit reactant fluid into the mixing chamber. Two mixing chamber fluid inlets formed in the support body structure communicate reactant fluid sources with the mixing chamber through the inlet openings. When retracted, a valve needle in the axial passage exposes the inlet openings to admit reactant fluids into the mixing chamber. When advanced, the needle closes off the inlet openings and pushes the mixed fluids from the mixing chamber. The valve needle includes three parallel helical grooves that help purge the mixing chamber of unreacted and reacted fluids. The grooves are arranged so that none of them can provide a fluid path between inlet openings when the needle is not retracted. Another embodiment of the apparatus includes three fluid inlet openings arranged to prevent reactant fluids from crossing over to opposing inlet openings. The method includes pre-filling the grooves before assembling the apparatus rather than allowing them to fill with foamable material during use.