Injection moulding machine

An injection moulding machine comprising:

• a plasticizing cylinder;
• at least one nozzle opening coupled to the plasticizing cylinder;
• a worm disposed to operate in the plasticizing cylinder, the worm having a through-hole;
• a hot runner;
• a plurality of cylinder chambers disposed upstream of the at least one nozzle opening, wherein each of the plurality of cylinder chambers defines a cross-sectional area, wherein the plurality of cylinder chambers are coupled to the plasticizing cylinder by the hot runner, wherein the hot runner includes a central valve that is disposed between two cylinder chambers so as to separate the two cylinder chambers from one another when the central valve is actuated;
• a needle shaped piston element disposed to operate in the cylinder chamber, wherein the needle shaped piston element defines a cross-sectional area that is smaller than each cylinder chamber cross-sectional area;
• a reverse flow barrier disposed between the plasticizing cylinder and the plurality of cylinder chambers so as to separate the plasticizing cylinder from the at least one cylinder chamber when the reverse flow barrier is actuated;
• and
• a piston device disposed in the worm through-hole so as to sealingly engage in the hot runner as the central valve.

An injection moulding machine, comprising:

• a plasticizing cylinder;
• at least one nozzle opening coupled to the plasticizing cylinder;
• a worm disposed to operate in the plasticizing cylinder, the worm having a tip;
• at least one cylinder chamber disposed upstream of the at least one nozzle opening, the at least one cylinder chamber defining a cross-sectional area;
• a needle shaped piston element and disposed to operate in the cylinder chamber, wherein the needle shaped piston element defines a cross-sectional area that is smaller than the cross-sectional area of the at least one cylinder chamber;
• and
• a reverse flow barrier disposed between the plasticizing cylinder and the at least one cylinder chamber so as to separate the plasticizing cylinder from the at least one cylinder chamber when the reverse flow barrier is actuated,
• wherein the reverse flow barrier includes the worm tip and a sealing seat that is correspondingly shaped to the worm tip, wherein the worm is adapted to be moved axially to a limited extent within the plasticizing cylinder, and wherein the sealing seat is disposed at an upstream positioned end of the cylinder chamber.