Process and apparatus for producing a dry-pressed moulding from a particulate or granular moulding material

Apparatus for producing a dry-pressed final molding having a first molding surface and an oppositely directed second molding surface in its final form from a particulate granular molding material comprising a first mold half and a vacuum shooting head disposed in opposed relation and forming a loading cavity (20) therebetween having a plane of separation, said first mold half having a first mold body and a first mold half forming surface with recessed partial faces corresponding to the final form of the first face of the final molding, said vacuum shooting head (14) having a shooting head body and a shooting head forming surface different from the corresponding final second face of the final molding in the final form thereof, said shooting head forming surface having recessed partial faces opposed to said recessed partial faces of said first mold half forming surface, said first mold half forming surface and said shooting head forming surface defining said loading cavity (20) and said shooting head being displaceable from said first mold half in a direction perpendicular to the plane of separation, said first mold half forming surface and said shooting head forming surface being rigid faces of said first mold half body and said shooting head body, respectively, or being made of an elastomeric layer which is rigidly supported by corresponding rigid supporting faces of said first mold half body and said shooting head body, respectively, said shooting head having a charge passage therethrough open to said loading cavity, means for applying a vacuum to said loading cavity for sucking the molding material into the loading cavity through said charge passage and to form a precompressed premold within said loading cavity, said premold having oppositely directed projections corresponding to said recessed partial faces of said first mold half forming surface and said shooting head forming surface, said shooting head being removable from said first mold half with the premold formed in the loading cavity being retained on said first mold half forming surface, a second mold half arranged to be aligned opposite said first mold half in place of said shooting head for pressing the premold into the final form, said second mold half having a second mold half body and a second molding half forming surface corresponding to the final form of the second molding surface of the final molding, said second mold half forming surface being substantially rigid or being made of an elastomeric material supported by a rigid supporting face on said second mold half body said second mold half forming surface being substantially free of recessed partial faces in the areas corresponding to said recessed partial faces of said shooting head forming surface, means for moving said second mold half body toward said first mold half body with the premold located in said first mold half forming surface and being contacted by the second mold half forming surface until the field of the distances between said second mold half forming surface and said first mold half surface in the direction perpendicular to the plane of separation corresponds to the field of thicknesses of the final molding whereby the premold is engageable by said second mold half forming surface with said projection on the face of said premold corresponding to said second face of said final molding before it engages the regions of the reduced wall thickness of said premold, the relationship of the heights h.sub.1, h.sub.2 of said loading cavity (20) in a direction perpendicular to said plane of separation to the corresponding heights g.sub.1, g.sub.2 between said first mold half forming surface and said second mold half forming surface in a direction perpendicular to said plane of separation at maximum approach of said second mold half body to said first mold half body being substantially constant over the total field defined by said first mold half forming surface within said loading cavity.