Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Deformation Analysis of Injection Molded Articles due to In-mold Residual Stress and Subsequent Cooling after Ejection

사출 성형품의 금형내 잔류음력과 이형후 냉각에 의한 후변형 해석

  • Published : 2002.02.01
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Abstract

Deformation analysis of injection molded articles whose geometry is considered as the assembly of thin flat plates has been conducted. For the in-mold analysis, thermo-viscoelastic stress calculation of thermo-rheologically simple amorphous polymer and in-mold deformation calculation considering the in-plane mold constraint have been done. Free volume theory has been used to represent the non-equilibrium density state during the fast cooling. At ejection, instantaneous deformation takes place due to the redistribution of in-mold residual stress. During out-of-mold cooling after ejection, thermoelastic model based on the effective temperature has been adopted for the calculation of out-of-mold deformation. In this study, emphasis is also made on the treatment with regard to lateral constraint types during molding process. Two typical mold geometries are used to test the numerical simulation modeling developed in this study.

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References

  1. Kim, I. H., Park, S. J., Chung, S. T. and Kwon, T. H. 1999, 'Numerical Modeling of Injection/Compression Molding for Center-Gated Disk: Part I. Injection Molding with Viscolastic Compression Fluid Model,' Polymer Engineering and Science, Vol. 39, No. 10, pp. 1930-1942 https://doi.org/10.1002/pen.11586
  2. Kim, I. H., Park, S. J., Chung, S. T. and Kwon, T. H., 1999, 'Numerical Modeling of Injection/Compression Molding for Center-Gated Disk: Part Ⅱ. Effect of Compression Stage,' Polymer Engineering and Science, Vol. 39, No. 10, pp. 1943-1951 https://doi.org/10.1002/pen.11587
  3. Lee, Y. B., Kwon, T. H. and Yoon, K. H., 'Numerical Prediction of Residual Stresses and Birefringences in Injection/Compression Molded Center-gated Disk: Part Ⅱ. Basic Modeling and Results for Injection Molding,' submitted to Polymer Engineering Science
  4. Lee, Y. B., Kwon, T. H. and Yoon, K. H., 'Numerical Prediction of Residual Stresses and Birefringences in Injection/Compression Molded Center-gated Disk: Part II. Effects of Processing Conditions,' submitted to Polymer Engineering Science
  5. St. Jacques, Michael, 1982, 'An Analysis of Thernal Warpage in Injection Molded Flat Parts Due to Unbalanced Cooling,' Polymer Engineering and Science, Vol. 22, No. 4, pp. 241-247 https://doi.org/10.1002/pen.760220405
  6. Jansen, K. M. B., 1994, 'Residual Stresses in Quenched and Injection Moulded Products,' International Polymer Processing, IX, pp. 82-89
  7. 정성택, 김진곤, 구본흥, 2000, '단섬유 보강 이방성 사출성형품의 휨 해석,' 대한기계학회논문집 A, Vol. 24, pp. 1968-1977
  8. Lee, E. H., Rogers, T. G. and Woo, T. C., 1965, 'Residual Stresses in a Glass Plate Cooled Symmetrically from Both Surfaces,'Journal of the American Ceramic Society, Vol. 48, No. 9, pp. 480-487 https://doi.org/10.1111/j.1151-2916.1965.tb14805.x
  9. Santhanam, N., Chiang, H. H., Himasekhar, K., Tuschak, Peter and Wang, K. K., 1992, 'Postmolding and Load-Induced Deformation Analysis of Plastic Parts in the Injection Molding Process,' Advances in Polymer Technology, Vol. 11, No. 2, pp. 77-89 https://doi.org/10.1002/adv.1991.060110201
  10. Kabanemi, K. K., Vaillancourt, H., W.ang, H. and Salloum, G., 1998, 'Residual Stresses, Shrinkage, and Warpage of Complex injection Molded Products: Numerical Simulation and Experimental Validation,' Polymer Engineering and Science, Vol. 38, No. 1, pp. 21-37 https://doi.org/10.1002/pen.10162
  11. Wang, H., Kabanemi, K. K.and Salloum, G., 2000, 'Numerical and Experimental Studies on the Ejection of Injection-Molded Plastic Products,' Polymer Engineering and Science, Vol. 40, No. 3, pp. 826-840 https://doi.org/10.1002/pen.11212
  12. Chiang, H. H., Hieber, C. A. and Wang, K. K., 1991, 'A Unified Simulation of the Filling and Postfilling Stages in Injection Molding: Part I. Formulation,' Polymer Engineering and Science, Vol. 31, No. 2, pp. 116-124 https://doi.org/10.1002/pen.760310210
  13. Chiang, H. H., Hieber, C. A. and Wang, K. K., 1991, 'A Unified Simulation of the Filling and Postfilling Stages in Injection Molding Part II: Experimental Validation,' Polymer Engineering and Science, Vol. 31, No. 2, pp. 125-139 https://doi.org/10.1002/pen.760310211
  14. Leonov, A. I., 1976, 'Non-equilibrium Thermo-dynamics and Rheology of Viscoelastic Polymer Media,' Rheol. Acta, Vol. 15, pp.85-98 https://doi.org/10.1007/BF01517499
  15. Tait, T. G., 1988, Physics and Chemistry of the Voyage of H.M.S. Challenge, Scientific Papers LXI, Vol. II, p. 1
  16. Shyu, G. D., 1993, 'Birefringence and Residual Stresses in Molded Articles of Amorphous Polymers,' PhD thesis, The University of Akron
  17. Jansen, K. M. B., Pantani, R. and Titomanlio, G., 1998, 'As-Molded Shrinkage Measurements on Polystyrene Injection Molded Products,' Polymer Engineering and Science, Vol. 38, No. 2, pp. 254-264 https://doi.org/10.1002/pen.10186
  18. Bergan, P. G. and Felippa, C. A., 1985, 'A Triangular Membrane Element with Rotational Degrees of Freedom,' Computer Methods in Applied Mechanics and Engineering, Vol. 50, pp. 25-69 https://doi.org/10.1016/0045-7825(85)90113-6
  19. Batoz, J. C., Bathe, C. J. and Ho, L. W., 1980, 'A Study of Three-Node Triangular Plate Bending Elements,' International Journal for Numerical Methods in Engineering, Vol. 15, pp. 1771-1812 https://doi.org/10.1002/nme.1620151205