Abstract: In an injection mold apparatus for manufacturing molded bodies from two types of plastic, a first and third injection units (4 and 6) are connected to a single mold cavity, and a core piece (15) which is movable back and forth occupies a region of the mold cavity when said core is in the blocking position, and said core in this position separates (by closing off) a first mold cavity region (associated with the first injection unit) and the entrance opening of material coming from the third injection unit (6) into the mold cavity from a second mold cavity region (which is connected to the first injection unit (4), whereby first the second mold cavity region is filled from the first injection unit and then, after the core (15) is drawn back, the region of the mold cavity initially occupied by said core, and the first mold cavity region, are filled from the third injection unit, and whereby the core has a recess, the improvement comprising providing the recess (37) in the blocking region of the core (15), whereb