注塑制品收缩规律的实验研究
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摘要
随着塑料性能的改善和注塑成型技术的发展，塑料制品的应用范围越来越广，同时人们对注塑制品的精度和质量要求越来越高，然而注塑制品的收缩不仅影响了制品的尺寸精度与表观质量，而且严重时还会引起制品结构变形与内在质量缺陷。精密注塑模具设计时的收缩率选取和注塑工艺参数设定已成为精密注塑件生产中的两大难题，所以很有必要对注塑制品收缩规律进行研究。
本课题在全面分析注塑成型收缩研究概况的基础上，用实验对注塑制品收缩规律进行了全方位的研究。首先，利用正交试验研究了注塑工艺参数对注塑制品的收缩率以及收缩各向异性(纵向收缩率和横向收缩率的差异)的影响规律，结果表明，在PP常用的工艺参数范围内，保压压力、保压时间和料温对注塑成型收缩影响较大，而保压压力和注射速度对注塑成型收缩各向异性影响较大。接着在正交实验的基础上，对几种典型形状塑件(方形、凸形、凹形、扇形)的收缩趋势进行了研究，证实了注塑制品是沿着几何中心向内收缩的。最后采用单因素试验法研究了注塑制品厚度对其收缩率的影响规律，发现注塑制品的厚度是影响塑件收缩率的一个重要因素，塑件的成型收缩率随塑件厚度增大而增大，但是这种增大的趋势是非线性的，而塑件收缩各向异性的趋势随着塑件厚度的增大而减小。
最后，本课题还利用注塑成型充模流动的静态可视化技术，观察了注塑成型中塑料熔体的稳态扩展流动形式，通过分析稳态扩展流的三个阶段，清楚了塑料熔体的充模流动过程，对注塑成型有了更深刻的认识。
With improvement of property of plastics and development of injection molding technology, injection molding products are used more and more widely, and with higher requirement of dimension accuracy and surface quality. But shrinkage of injection molding products can influence the dimension accuracy and surface quality, even cause structural distortion or in-side defects. Selection of shrinkage rate and process parameter becomes a difficulty in precision plastic parts production. So it is necessary to study the shrinkage laws of injection molding products.
On the basis of roundly analyzing study state of shrinkage of injection molding products, shrinkage laws of injection molding products is fully studied via experiment in this paper, At first, the influence of process parameter on shrinkage rate and shrinkage anisotropy (difference between transverse shrinkage rate and longitudinal shrinkage rate) of injection molding products is studied through orthogonal experiment. It's found that holding pressure, holding time and melt temperature are significant effect factors on the shrinkage rate of injection molding products, while holding pressure and injection rat influence shrinkage anisotropy greatly. On the basis of the former orthogonal experiment, shrinkage trend of some injection molding parts with typical shape (square, convex, concave, sector-shaped) are studied experimentally. Result indicated that plastic parts shrink along its geometry centre. Then a single factor experiment is used to research the regularity of influence of thickness on shrinkage rate. It is indicated that thickness is an important factor of shrinkage rate, the shrinkage rate increase with thickness non-linearly, while shrinkage anisotropy reduce with thickness.
At last, a static visualization method for filling of injection molding is used to observe the steady expanding flow of the melt plastic in mold cavity. According to the analysis of the three stages of expanding flow, filling in injection molding is understood more impressively
本课题在全面分析注塑成型收缩研究概况的基础上，用实验对注塑制品收缩规律进行了全方位的研究。首先，利用正交试验研究了注塑工艺参数对注塑制品的收缩率以及收缩各向异性(纵向收缩率和横向收缩率的差异)的影响规律，结果表明，在PP常用的工艺参数范围内，保压压力、保压时间和料温对注塑成型收缩影响较大，而保压压力和注射速度对注塑成型收缩各向异性影响较大。接着在正交实验的基础上，对几种典型形状塑件(方形、凸形、凹形、扇形)的收缩趋势进行了研究，证实了注塑制品是沿着几何中心向内收缩的。最后采用单因素试验法研究了注塑制品厚度对其收缩率的影响规律，发现注塑制品的厚度是影响塑件收缩率的一个重要因素，塑件的成型收缩率随塑件厚度增大而增大，但是这种增大的趋势是非线性的，而塑件收缩各向异性的趋势随着塑件厚度的增大而减小。
最后，本课题还利用注塑成型充模流动的静态可视化技术，观察了注塑成型中塑料熔体的稳态扩展流动形式，通过分析稳态扩展流的三个阶段，清楚了塑料熔体的充模流动过程，对注塑成型有了更深刻的认识。
With improvement of property of plastics and development of injection molding technology, injection molding products are used more and more widely, and with higher requirement of dimension accuracy and surface quality. But shrinkage of injection molding products can influence the dimension accuracy and surface quality, even cause structural distortion or in-side defects. Selection of shrinkage rate and process parameter becomes a difficulty in precision plastic parts production. So it is necessary to study the shrinkage laws of injection molding products.
On the basis of roundly analyzing study state of shrinkage of injection molding products, shrinkage laws of injection molding products is fully studied via experiment in this paper, At first, the influence of process parameter on shrinkage rate and shrinkage anisotropy (difference between transverse shrinkage rate and longitudinal shrinkage rate) of injection molding products is studied through orthogonal experiment. It's found that holding pressure, holding time and melt temperature are significant effect factors on the shrinkage rate of injection molding products, while holding pressure and injection rat influence shrinkage anisotropy greatly. On the basis of the former orthogonal experiment, shrinkage trend of some injection molding parts with typical shape (square, convex, concave, sector-shaped) are studied experimentally. Result indicated that plastic parts shrink along its geometry centre. Then a single factor experiment is used to research the regularity of influence of thickness on shrinkage rate. It is indicated that thickness is an important factor of shrinkage rate, the shrinkage rate increase with thickness non-linearly, while shrinkage anisotropy reduce with thickness.
At last, a static visualization method for filling of injection molding is used to observe the steady expanding flow of the melt plastic in mold cavity. According to the analysis of the three stages of expanding flow, filling in injection molding is understood more impressively
引文
[1] 王庆利，基于Moldflow注塑制品收缩规律模拟实验研究：(硕士学位论文)．大连：大连理工大学，2003
[2] Robert G. Egbers, Kieth G. Johnson. Shrinkage Properties of HDPE-An Aid to the Mold Design. SPE Pacific Technical Conferences and Technical Display PACTEC Plastics Technology Advances, 1980: 65-72.
[3] Gird P., Hebert L. P., Salloum G. Computer Simulation of the Injection Molding Shrinkage for HDPE. ANTEC, 1985.
[4] Georgs Sallourn, Denis Charland, Berard Sanachgrin. Moldeling of Shringkage for HDPE Disk Shape. ANTEC, 1992.
[5] B. Sanschagrin, S. Rivard, L. P. Hebert et al. Shrinkage Analysis of Reinforced injection Molded Parts. ANTEC, 1989.
[6] VLeo and Ch. Curelliez. The Effect of the Packing Parameters, Gate Geometry, and Mold Elasticity on the Final Dimensions of a Molded Part. Polymer Engineering and Science, 1996, 36: 1961-1969.
[7] B. H. Lee. Variation of Part Wall Thickness to Reduce Warpage of Injection-Molded Parts: Robust Design against Process Variability. Polymer and Plastic Technol. Eng., 1997, 36(5):
[8] 宋满仓，荆晓南，赵丹阳．扇形制品注射成型的收缩特性研究．工程塑料应用 2006，2：31-33．
[9] 俞芙芳，俞芸，张清辉注射成型收缩与模具尺寸．福建工程学院学报，2005 Vol．3 No．1
[10] 荆晓楠，注塑模具成型零件工作尺寸算法分析及实验研究：(硕士学位论文)．大连：大连理工大学，2003．
[11] 杨凤霞，张焱．PA成型收缩率与注塑工艺条件的关系．广东塑料，2005，10：44-47
[12] 苏开华，陈锋．精密注塑成型中温度对制品收缩率的影响．广东塑料，2005，04．
[13] 付中兴，王学文，减小聚甲醛注塑制品收缩率的工艺研究．工程塑料应用，2001，29(60)．
[14] 王利霞，王蓓，申长雨．工艺参数对注塑制品质量的影响研究．郑州大学学报 2003，09：62-66
[15] 张克惠，寇开昌．注塑参数对聚苯乙烯收缩率的影响．中国塑料，1995，9(4)：45-49．
[16] 李倩，王松杰，申长雨等．模具设计中收缩率的预测．电加工与模具，2002(5)：53-54．
[17] 于同敏，路全胜，葛东东．注射成型收缩与塑件尺寸精度．模具工业，1995(8)：36-40．
[18] R. Y Chang, B. D. TSAUR. Experimental and Theoretical Studied of Shrinkage, Warp and Sink Marks of Crystalline Polymer injection Molded Parts. Polymer Engineering and Science, 1995, Vol. 35, No. 15: 2115-2125.
[19] W. Discipio, A. Wagle, S. P. Mccarthy. Verification Mold for Flow, Cooling, Shrinkage and Warpage Analysis. ANTEC, 1990.
[20] Whitfield G. Haisitend, James R. Rinderie, Nam P. Suh. Application of a Variable Volume Mold to the Shrinkage Control of Injection Molded Parts. ANTEC. 1979.
[21] W. B. Hoven-Nievelstein, G. Menges. Studies on the Shrinkage of Thermoplastics. ANTEC, 1985.
[22] K. M. B. JANSEN, G. TITOMANLIO. Effect of Pressure History on Shrinkage and Residual Stresses-Injection Molding With Constrained Shrinkage. Polymer Engineering and Science, 1996, Vol. 36, No. 15: 2029-2039.
[23] 王志连．影响注塑成型收缩率的因素及收缩率的选择．福建农机，1999，增刊：68-71．
[24] S. F. WALSH. Shrinkage and Wapage Prediction for Injection Molded Components. Journal of Reinforced Plastics and Composites, Vol. 12-July 1993: 769-776.
[25] 李海梅，刘永志，申长雨等．注塑件翘曲变形的CAE研究．中国塑料，2003，3：53-58．
[26] 李海梅，申长雨，顾元宪．注塑件残余应力计算及翘曲变形分析．流变学进展，1999，11：431-435．
[27] 祝铁丽．注塑成型制品收缩率数值模拟方法的工程化研究：(博士学位论文)．大连：大连理工大学，2001．
[28] 祝铁丽，王敏杰．注塑制品收缩率研究进展．模具技术，2002．1：10-12．
[29] 郭志英，阮雪榆，李德群．注塑制品翘曲变形数值分析模型．中国机械工程，2002，9：1515-1517．
[30] 郭志英，李德群．注塑制品翘曲变形有限元数值模拟的误差分析．华中理工大学学报，2000，3：63-65．
[31) T. matsuoka. Integrated Simulation to Predict Warpage of Injection Molded Parts. Polymer Engineering and Science, 1991, 31(14): 1043-1050.
[32] Gordillo. A., Ariza, D. Sanchez-Soto, M, Maspoch, M. LI. Shrinkage Predictions of Injection Moulded Parts in Semi-Crystalline Polymers Experimental Verification. ANTEC, 1999.
[33] Chetan P. Nirkhe, Satish S. Sharma, Carol M. F. Barry. Evaluating Factors Affecting Shrinkage Predictions. ANTEC, 2003
[34] 马浩军，胡广洪，阮雪榆．利用Moldflow软件分析解决注塑件翘曲问题．模具技术，2005，5：55-58．
[35] 郑晓培，路书芬，王利霞，申长雨．工艺参数对注塑制品沉降斑的影响分析及优化．工程塑料应用，2006．07．
[36] Hidetoshi YOKOI, Takaki HAYASHI, Hiroyuki HIRAOKA. Visual analysis of the process of plastic flow inside an injection mold. 生产研究，1987, 39(7); 309
[37) 谢鹏程．杨卫民．注射充模过程可视化实验装置的研制．塑料．2004，33(2)：87-89．
[38] 杨卫民，谢鹏程，杨高品．注射成型多型腔充填不平衡现象的产生机理(1)——模具流道系统中熔体流动行为的研究．中国塑料．第18卷第11期．
[39] 杨卫民，谢鹏程，杨高品．注射成型多型腔充填不平衡现象的产生机理(2)—模具流道系统中熔体温度分布的研究．中国塑料．第18卷第12期．
[40] 孙翔，杨卫民，丁玉梅，王兴天．基于可视化的注射成型制品缺陷及其产生机理的研究．中国塑料．2005，12：64-68．
[41] 金志明，马艳娥，高福荣．注塑成型塑化过程的可视化实验研究．中国塑料．3005，09：73-76．
[42] 宋满仓，黄银国，赵丹阳．注塑模具设计与制造实践．北京：机械工业出版社，2003．
[2] Robert G. Egbers, Kieth G. Johnson. Shrinkage Properties of HDPE-An Aid to the Mold Design. SPE Pacific Technical Conferences and Technical Display PACTEC Plastics Technology Advances, 1980: 65-72.
[3] Gird P., Hebert L. P., Salloum G. Computer Simulation of the Injection Molding Shrinkage for HDPE. ANTEC, 1985.
[4] Georgs Sallourn, Denis Charland, Berard Sanachgrin. Moldeling of Shringkage for HDPE Disk Shape. ANTEC, 1992.
[5] B. Sanschagrin, S. Rivard, L. P. Hebert et al. Shrinkage Analysis of Reinforced injection Molded Parts. ANTEC, 1989.
[6] VLeo and Ch. Curelliez. The Effect of the Packing Parameters, Gate Geometry, and Mold Elasticity on the Final Dimensions of a Molded Part. Polymer Engineering and Science, 1996, 36: 1961-1969.
[7] B. H. Lee. Variation of Part Wall Thickness to Reduce Warpage of Injection-Molded Parts: Robust Design against Process Variability. Polymer and Plastic Technol. Eng., 1997, 36(5):
[8] 宋满仓，荆晓南，赵丹阳．扇形制品注射成型的收缩特性研究．工程塑料应用 2006，2：31-33．
[9] 俞芙芳，俞芸，张清辉注射成型收缩与模具尺寸．福建工程学院学报，2005 Vol．3 No．1
[10] 荆晓楠，注塑模具成型零件工作尺寸算法分析及实验研究：(硕士学位论文)．大连：大连理工大学，2003．
[11] 杨凤霞，张焱．PA成型收缩率与注塑工艺条件的关系．广东塑料，2005，10：44-47
[12] 苏开华，陈锋．精密注塑成型中温度对制品收缩率的影响．广东塑料，2005，04．
[13] 付中兴，王学文，减小聚甲醛注塑制品收缩率的工艺研究．工程塑料应用，2001，29(60)．
[14] 王利霞，王蓓，申长雨．工艺参数对注塑制品质量的影响研究．郑州大学学报 2003，09：62-66
[15] 张克惠，寇开昌．注塑参数对聚苯乙烯收缩率的影响．中国塑料，1995，9(4)：45-49．
[16] 李倩，王松杰，申长雨等．模具设计中收缩率的预测．电加工与模具，2002(5)：53-54．
[17] 于同敏，路全胜，葛东东．注射成型收缩与塑件尺寸精度．模具工业，1995(8)：36-40．
[18] R. Y Chang, B. D. TSAUR. Experimental and Theoretical Studied of Shrinkage, Warp and Sink Marks of Crystalline Polymer injection Molded Parts. Polymer Engineering and Science, 1995, Vol. 35, No. 15: 2115-2125.
[19] W. Discipio, A. Wagle, S. P. Mccarthy. Verification Mold for Flow, Cooling, Shrinkage and Warpage Analysis. ANTEC, 1990.
[20] Whitfield G. Haisitend, James R. Rinderie, Nam P. Suh. Application of a Variable Volume Mold to the Shrinkage Control of Injection Molded Parts. ANTEC. 1979.
[21] W. B. Hoven-Nievelstein, G. Menges. Studies on the Shrinkage of Thermoplastics. ANTEC, 1985.
[22] K. M. B. JANSEN, G. TITOMANLIO. Effect of Pressure History on Shrinkage and Residual Stresses-Injection Molding With Constrained Shrinkage. Polymer Engineering and Science, 1996, Vol. 36, No. 15: 2029-2039.
[23] 王志连．影响注塑成型收缩率的因素及收缩率的选择．福建农机，1999，增刊：68-71．
[24] S. F. WALSH. Shrinkage and Wapage Prediction for Injection Molded Components. Journal of Reinforced Plastics and Composites, Vol. 12-July 1993: 769-776.
[25] 李海梅，刘永志，申长雨等．注塑件翘曲变形的CAE研究．中国塑料，2003，3：53-58．
[26] 李海梅，申长雨，顾元宪．注塑件残余应力计算及翘曲变形分析．流变学进展，1999，11：431-435．
[27] 祝铁丽．注塑成型制品收缩率数值模拟方法的工程化研究：(博士学位论文)．大连：大连理工大学，2001．
[28] 祝铁丽，王敏杰．注塑制品收缩率研究进展．模具技术，2002．1：10-12．
[29] 郭志英，阮雪榆，李德群．注塑制品翘曲变形数值分析模型．中国机械工程，2002，9：1515-1517．
[30] 郭志英，李德群．注塑制品翘曲变形有限元数值模拟的误差分析．华中理工大学学报，2000，3：63-65．
[31) T. matsuoka. Integrated Simulation to Predict Warpage of Injection Molded Parts. Polymer Engineering and Science, 1991, 31(14): 1043-1050.
[32] Gordillo. A., Ariza, D. Sanchez-Soto, M, Maspoch, M. LI. Shrinkage Predictions of Injection Moulded Parts in Semi-Crystalline Polymers Experimental Verification. ANTEC, 1999.
[33] Chetan P. Nirkhe, Satish S. Sharma, Carol M. F. Barry. Evaluating Factors Affecting Shrinkage Predictions. ANTEC, 2003
[34] 马浩军，胡广洪，阮雪榆．利用Moldflow软件分析解决注塑件翘曲问题．模具技术，2005，5：55-58．
[35] 郑晓培，路书芬，王利霞，申长雨．工艺参数对注塑制品沉降斑的影响分析及优化．工程塑料应用，2006．07．
[36] Hidetoshi YOKOI, Takaki HAYASHI, Hiroyuki HIRAOKA. Visual analysis of the process of plastic flow inside an injection mold. 生产研究，1987, 39(7); 309
[37) 谢鹏程．杨卫民．注射充模过程可视化实验装置的研制．塑料．2004，33(2)：87-89．
[38] 杨卫民，谢鹏程，杨高品．注射成型多型腔充填不平衡现象的产生机理(1)——模具流道系统中熔体流动行为的研究．中国塑料．第18卷第11期．
[39] 杨卫民，谢鹏程，杨高品．注射成型多型腔充填不平衡现象的产生机理(2)—模具流道系统中熔体温度分布的研究．中国塑料．第18卷第12期．
[40] 孙翔，杨卫民，丁玉梅，王兴天．基于可视化的注射成型制品缺陷及其产生机理的研究．中国塑料．2005，12：64-68．
[41] 金志明，马艳娥，高福荣．注塑成型塑化过程的可视化实验研究．中国塑料．3005，09：73-76．
[42] 宋满仓，黄银国，赵丹阳．注塑模具设计与制造实践．北京：机械工业出版社，2003．