see fig1 then the molded plastics material cooling step will be started said cooling step being performed through the reduction assemblies 4 and 5 holding the plastics material 3 in its set position on the mold 2 in particular the mentioned cooling is performed according to the invention by raising or detaching the movable panel 7 from the sidewall 6 of the bell element see fig5 thereby providing a large perimetrical opening 19 therethrough the fans 8 will eject air jets 20 inside the bell element and through the outer surface of the plastics material or molded article 3 in this connection it should be pointed out that the hot air streams will exit through the same opening 19 see the thickened arrows of fig3 according to the modified embodiment of fig6 a like opening 21 can be advantageously formed also in the bottom of the bell element by raising or detaching said sidewall 6 thereof from the reduction assembly 4 while holding it in a gripping relationship on the plastics material 3 a further improved cooling moreover can be provided by the fans 8 which in the modified embodiment shown in fig7 are arranged at the level of the mentioned ports provided through the side wall 6 of the bell element thus owing to the invention which in the illustrated embodiments provides.