Extruding system and method of extruding a mixture of a polymeric material and a blowing agent

An extruding system, comprising:

• a mixing unit configured to mix a polymeric material with a blowing agent and to form a mixture of the polymeric material and the blowing agent, the mixing unit includes a mixing cartridge, a first mixing chamber longitudinally extending in the mixing cartridge, a second mixing chamber longitudinally extending in the mixing cartridge, a third mixing chamber longitudinally extending in the mixing cartridge, a first mixing screw having at least two groove portions different from each other in curvatures and disposed in the first mixing chamber in a first direction, a second mixing screw having at least two groove portions different from each other in curvatures and disposed in the second mixing chamber in the first direction, a third mixing screw having at least two groove portions different from each other in curvatures and disposed in the third mixing chamber in the first direction;
• a first port coupled to the first mixing chamber, disposed between the at least two groove portions of the first mixing screw and configured to provide the blowing agent into the first mixing chamber,
• a second port coupled to the second mixing chamber, disposed between the at least two groove portions of the second mixing screw and configured to provide the blowing agent into the second mixing chamber;
• a third port coupled to the third mixing chamber, disposed between the at least two groove portions of the third mixing screw and configured to provide the blowing agent in to the third mixing chamber, and
• an injection unit coupled to the mixing unit and configured to inject the mixture;
• and
• a molding device disposed under the mixing unit and the injection unit,
• wherein the first mixing chamber is disposed over and vertically aligned with the second mixing chamber,
• the second mixing chamber is horizontally aligned with and substantially coplanar with the third mixing chamber,
• the mixture is conveyable within and along the mixing cartridge to sequentially in contact with the at least two groove portions of the first mixing screw, the at least two groove portions of the second mixing screw and the at least two groove portions of the third mixing screw and to sequentially pass through the first port, the second port and the third port,
• the mixture is flowable downwardly and sequentially along the first mixing chamber and the second mixing chamber,
• the molding device includes a feeding passage and a molding cavity in communication with the feeding passage, and the feeding passage extends in a second direction perpendicular to the third mixing screw,
• the injection unit is vertically extended between the mixing unit and the molding device in the second direction perpendicular to the first direction and includes a nozzle engageable with the feeding passage and is configured to inject the mixture in the direction perpendicular to the third mixing screw,
• the first mixing chamber, the second mixing chamber and the third mixing chamber are substantially orthogonal to the injection unit, and
• the first mixing chamber has a first pressure, the second mixing chamber has a second pressure, the third mixing chamber has a third pressure, the first pressure is greater than the second pressure, and the second pressure is greater than the third pressure.