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The Threaded Rod Application in Injection Molding Machine

Date:2018-01-15

Threaded Rod is an important part of the injection molding machine. Its role is to convey, compact, melt, agitate and pressurize the plastic. All of this is done by the rotation of the threaded rod in the barrel. As the screw rotates, the plastic will rub and reciprocate between the inner wall of the barrel, the bottom surface of the screw groove, the propeller surface, and the plastic and plastic. The advancing plastic is the result of this combination of movements, and the heat generated by friction is also absorbed to increase the temperature of the plastic and to melt the plastic. The structure of the screw will directly affect the extent of these effects.

General injection threaded rod structure, but also to improve the quality of plastics designed to split screw, barrier screw or split screw. In fact, the structure of the barrel is a middle opening of the mouth of the tube. In plastics plasticization process, its forward and mixing power are derived from the threaded rod and barrel relative rotation. According to the different forms of the plastic screw in the screw slot, the threaded rod is generally divided into three sections: solid conveying section (also called feeding section), melting section (also called compression section), homogenization section.

Plastic in the melting temperature near the contact with the cylinder plastic has begun to melt to form a layer of melt film. When the melt film thickness exceeds the gap between the threaded rod and the barrel, the top of the spiral rib scrapes the melt film radially from the inner wall of the barrel toward the root of the spiral rib so as to gradually converge into a spiral flow area on the propeller surface of the spiral rib - Puddle.

Due to the gradual deepening of the depth of the molten section of the threaded rod groove and extrusion pool, the solid bed is squeezed to the inner wall of the barrel, thus accelerating the hot barrel to the solid bed heat transfer process. At the same time, the rotation of the screw shears the melt film between the solid bed and the inner wall of the barrel to melt the solid between the melt film and the solid bed interface. As the spiral of the solid bed moves forward, the volume of the solid bed gradually decreases, while the volume of the pool gradually increases. If the thickness of the solid bed decreases less than the speed at which the depth of the flute becomes shallow, the solid bed may partially or completely block the flute to cause plasticization to fluctuate or due to a sharp increase in frictional heat generation due to local pressure increase Local overheating.

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