Pressless injection molding apparatus

Claim 1

Apparatus for injection molding comprising: a first stationary mold plate; a second mold plate linearly movable relative to said first mold plate, the adjacent faces of said mold plates being formed to define a mold cavity therebetween; at least one of said mold plates having a passageway formed therein to allow injection of fluid plastic material into said mold cavity; a backing plate mounted for limited linear movement relative to the rear face of said second mold plate; the adjacent faces of said backing plate and second mold plate defining a false cavity therebetween, said false cavity being filled with a substantially incompressible compliant material and being in communication with said passageway; means operatively connected to one of said mold plates for initially urging said mold plates together and for urging said backing plate toward said second mold plate; and means in communication with said passageway for injecting fluid plastic material under pressure into said passageway to fill said mold cavity and to exert pressure on said compliant material to generate forces urging the mold plates together to counteract the forces generated within the mold cavity.