Vertical injection molding machine molded article shrinkage (VII)

Date：2015-10-22 00:10:59

Shrinkage of 2.3 injection molded article

        2.1 contraction mechanism vertical injection molding machine injection molding products made analysis and whether you need to calculate the thickness direction of the systolic displacement. Shrink shrink on its path A point of temperature conditions at various points of a great relationship. Injection molded articles for the temperature conditions of a point from the influential factors, one between this point and the gate; the second is the extent of which is cooled mold; third the thickness of plastic parts here.
        In the flow, pressure high-temperature melt process continuously flowing and become heat, so when the end of the dwell temperature from the gate closer points higher; farther on a pitch mold cooling circuits of injection molding products, The smaller extent by cooling the mold, the temperature will drop more slowly; a large part of the injection molded product thickness, the temperature will drop slower. Before the beginning of the contraction process, the temperature of each point on the path A point decline slower contraction, the contraction can occur during shrinking the greater systolic displacement A point along the flow path is greater.
        2.2 basis of experimental studies carried out on the following conclusions:
        (L) vertical injection molding machine mold filling process, the polymer chains oriented along the flow direction of the flow under the action of shear stress, and the entanglement of the polymer molecular chains are arranged along the flow direction are connected to each other to form a strip Endpoint flow path located gate. In the cooling process, the point of injection molded article on When the pressure drops to equal to atmospheric pressure, by the contractile force from their respective flow path along the flow path is contracted during shrinking.
        (2) When the vertical injection molding machine injection molding products produced weld marks, shrink direction and magnitude of welding marks on the point by the two flow paths generates this point to this point on the weld lines combined vector contractile force of the decision ; shrinkage direction and magnitude scar near the weld point, thus the synthesis of contractile force vectors point belongs to this point in the flow path and weld marks contractile force of the decision on this point.
        (3) cooling phase in the vertical injection molding machine, if a point on the injection molded article shrinkage along its flow path by directly impeding the mold cavity, can contraction this point is its displacement along the flow path of the contraction in Here cavity boundary component direction, and so close to this point is not directly impede shrinkage cavities point has also been indirectly impede the mold cavity.
        (4) in the thickness direction of the vertical injection molding machine injection molding products, if the points do not make the distance between the molecules in the thickness direction of the flow path contraction get along narrow, then the polymer surface layer may be within the scope of their athletic ability move to the core, which is shrinking the thickness direction from the surface of the injection molded article pointing core injection molded article.
        (5) The molecular motion capability vertical injection molding machine injection products surface layer controls the shrinkage of injection molded products. When the polymer injection molded article athletic ability of the surface layer is extremely weak, injection molded article dimensions no longer change. The above conclusions will be applied within the outer mold and the mold cooling stage cooling stage of vertical injection molding machine Injection Molding shrinkage analysis and calculation process. In calculating the contraction process vertical injection molding machine injection molding products surface layer at a point A, each time a step forward, it is determined systolic displacement A point along the flow path in accordance with the degree of narrowing of each hematocrit point A point on the flow path, according to A point to be bound by circumstances to adjust its contraction displacement, then judge

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