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Research Papers

Effect of Die Lip Geometry on Polymer Extrudate Deformation in Complex Small Profile Extrusion

[+] Author and Article Information
Huiqing Tian

School of Mechanical Engineering,
Dalian University of Technology,
Dalian 116024, China
e-mail: huiqingt@hotmail.com

Danyang Zhao

School of Mechanical Engineering,
Dalian University of Technology,
Dalian 116024, China
e-mail: zhaody@dlut.edu.cn

Minjie Wang

School of Mechanical Engineering,
Dalian University of Technology,
Dalian 116024, China
e-mail: mjwang@dlut.edu.cn

Yifei Jin

Department of Mechanical and
Aerospace Engineering,
University of Florida,
Gainesville, FL 32611
e-mail: yifei.jin@ufl.edu

1Corresponding author.

Manuscript received July 10, 2014; final manuscript received December 6, 2016; published online January 25, 2017. Assoc. Editor: Allen Y. Yi.

J. Manuf. Sci. Eng 139(6), 061005 (Jan 25, 2017) (9 pages) Paper No: MANU-14-1368; doi: 10.1115/1.4035419 History: Received July 10, 2014; Revised December 06, 2016

The extrusion of polymer profile products with complex microcross section is difficult due to the extrudate deformation, especially for the profile with multihollow lumens and inner ribs. In order to investigate the effect of die lip geometry on extrudate deformations, three-dimensional simulations have been undertaken for typical small profile extrusions both inside and outside the die using finite-element method (FEM). The Carreau model was used to describe the shear-thinning behavior of polymer melt. The systematic definitions of the die lip geometric parameters and evaluations of the extrudate deformations were proposed. It was found that the thickness and profile deformations happen asynchronously, and the existence of the inner rib changes the global deformation, which cannot be predicted by a deformation combination of the basic geometries. Among the investigated die lip geometric parameters, the wall thickness ratio has the most pronounced effect on both thickness and external profile deformations of the extrudates, with the maximum variation of more than 80%. The decrease of the hollow ratio significantly reduces the extrudate deformation extent, especially the extrudate external profile and the extrudate thickness of the thin-wall region. Even with uniform thickness, the location and shape of the inner rib also generate extrudate deformations not only on the inner rib but also on the thickness of the outer ring at the region not connected with it, by a minor variation level of 5–25%. Comprehensive understandings on the mechanism of extrudate deformations and effects of die lip geometry were obtained. Some hints for small profile die design were provided accordingly. Numerical results showed qualitative and quantitative agreement with the experiments.

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Figures

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Fig. 1

Schematic diagram of flow domain and boundary conditions for profile extrusion flow from a double-lumen die and the accompanying extrudate deformation phenomenon

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Fig. 2

Schematic illustrations of die lip geometries for a double-lumen profile

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Fig. 3

Typical finite-element mesh used in the computation

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Fig. 4

Assembly of the double-lumen extrusion die and a zoom in vicinity of the die exit

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Fig. 5

Extrudate profiles along the flow direction for cases A1, A3, and A6

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Fig. 6

Contour variables on the coordinate planes and extrudate cross sections for the extrusion flow of case A1

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Fig. 7

Velocity counter on the die exit and the final extrudate profile represented by the solid black line for (a) case A1, (b) case A3, and (c) case A6

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Fig. 8

Extrudate swell and deformation ratio as a function of the wall thickness ratio αT

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Fig. 9

Velocity counter on the die exit and the final extrudate profile represented by the solid black line for (a) case B1, (b) case B3, and (c) case B6

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Fig. 10

Extrudate swell and deformation ratio as a function of the hollow ratio αH

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Fig. 11

Velocity counter on the die exit and the final extrudate profile represented by the solid black line for (a) case C1 and (b) case C6

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Fig. 12

Extrudate swell and deformation ratio as a function of the eccentricity ratio αE

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Fig. 13

Velocity counter on the die exit and the final extrudate profile represented by the solid black line for (a) case D1 and (b) case D6

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Fig. 14

Extrudate swell and deformation ratio as a function of the curvature ratio αC

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Fig. 15

Cross section of the double-lumen extrudate

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