塑料异型材的挤出胀大及其引起的不规则挤出形变，是异型材挤出制品尺寸控制的难点所在。针对此类问题，采用有限元方法研究了典型异型材口模构型要素如T型口模分支立臂位置、90°夹角L型口模过渡区域转角、L型口模两臂夹角等对挤出形变和模流平衡的影响。结果表明，随T型口模分支立臂由挤出中心位置向右偏移，挤出后的型材挤出中心位置发生偏移，立臂顶端向右上变形，从而使得挤出形变加剧，需要在模具设计时将立臂顶端向挤出中心方向进行补偿。在90°夹角L型口模内外转角处设置过渡圆角，有助于模具出口处的模流平衡。L型异型材两臂夹角在挤出后变大，且初始设计夹角为60°和90°时变化较大，需要根据相关实验找出其初始设计夹角与挤出后的实际夹角对应关系，以便在模具设计过程中进行参照。上述研究结果对逆向挤出问题的求解、异型材挤出模具的设计和口模构型的确定有着一定的参考意义。%According to the problems that the extrusion profile size is difficult to control because of the extrusion swell and its irregular extrusion deformation,finite element method was used to analyze the influences of the typical die structure configura-tion elements such as the branch vertical arm position of the T profile die,the transitionfillet of the L profile die with 90°angle and the angle of the two arms of the L profile on the extrusion deformation and mold-flow equilibrium. The results show that offset to the right of the branch vertical arm from extrusion center can cause the offset of the extrusion center,leading to a upper right direc-tion deformation of the vertical arm top,which intensifies the extrusion deformation and needs to compensate the vertical arm top towards the direction of extrusion center during the die design. The transitionfillet is set in the internal and external angles of transi-tion region of the L type die with 90°angle can be helpful to the mold-flow equilibrium at the die exit. The angle of the two arms of L type die becomes larger after extrusion,and the changes are bigger when the initial design angle is 60° and 90°,so the corresponding relationship between the initial design angle and the actual angle after extrusion needs to be found according to the relevant experi-ments,which can provide reference in the mould design process. This studying results have a certain reference value for the solution of the inverse extrusion problems,design of the profile extrusion die and determination of the die structure configuration.
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