用户名: 密码: 验证码:
薄壁塑件注射成型可控制造的研究
详细信息    本馆镜像全文|  推荐本文 |  |   获取CNKI官网全文
摘要
随着笔记本电脑和手提电话等3C产品逐渐朝着“轻、薄、短、小”方向发展,薄壁注射成型因具有减轻产品重量及减小产品外观尺寸、节约材料和降低成本等优点成为了研究的热点。由于对该技术的研究才刚刚开始,还没有形成基本的理论体系,而且国内对这方面的研究非常少,所以本研究的开展将为研究薄壁注射成型特性积累经验,并为深入开展薄壁零件注射成型的可控制造的研究打下良好的基础。
     本课题设计了一套一模四腔模具,可以同时成型4种不同壁厚(0.3mm、0.5mm、0.8mm、1.0mm)零件。采用Moldflow MPI5.0软件Flow/3D仿真分析和实验研究了不同参数(熔体温度、注射速度、零件壁厚)对薄壁件注射成型特性的影响。
     采用Moldflow MPI/Flow 3D仿真研究了熔体温度、注射速度、制品厚度等参数对薄壁成型时其剪切速率分布的影响,结果表明:在制品流动方向上,浇口附近的剪切速率远大于其它各处的剪切速率,并随着距离的增加而迅速降低。距浇口1.5mm附近处到制品的末端,剪切速率的变化并不明显,稳定在2000~4000S~(-1)之间。在厚度方向上,芯层的剪切速率最低,向次表层方向逐渐增大,并在距表面0.1mm处达到最大值,然后再往表层逐渐降低,直至表层,但表层的剪切速率仍然大于芯部。薄壁越薄,浇口处的剪切速率越大,但在末端则相差无几。
     采用同步热分析仪,实验研究了薄壁制品在流动方向和厚度方向上其结晶度的分布规律,结果表明:从制品流动方向上来看,浇口处的熔融热焓明显要高于其他位置上的;沿着熔体流动方向,熔融热焓随着与浇口距离的增大而减小,在5mm处至制品末端,其变化不明显;从制品厚度方向上来看,从中心到表面,结晶热焓随着距离的增加而增大,直到表面附近0.08mm达到最大,随后表面的结晶热焓又降低,但是仍然比中心部位的大很多。
     根据薄壁塑件使用性能对结晶度高低的不同要求,可以通过调整薄壁塑件注射成型时的熔体温度和注射速率参数,以控制成型后薄壁塑件的结晶度,从而实现薄壁塑件的可控制造。
With the 3C(computer, communication and consumer electronics) products such as notebook computer and mobile telephone etc. becoming lighter, thinner, shorter and smaller, Thin wall injection molding(TWIM) becomes one hotspot of research because of reducing products weights, minifying size, economizing materials and lowing costs etc. Because the research on TWIM is still at the primary stage, and the theory system has not formed completely, moreover, it is few in domestic, this paper can reinforce domestic research in this domain, and will built the good foundation for the future research.
     A mould was designed in this paper, which can simultaneously mold four parts of different thickness (0.3, 0.5, 0.8, 1.0 mm). By utilizing the Moldflow MPI5.0 software Flow/3D module simulation analysis and injection molding experiment, we studied the effect of different process parameters (melt temperature, injection rate and the thickness of parts) to thin-wall injection molding characteristics.
     The effects of the different parameters (melt temperature, injection rate and the thickness of parts) to the distribution of shear rate in thin-wall injection molding were researched by MPI/Flow 3D software. The results show the shear rate close to the gate is much higher than at other positions, and decreases with the distance to the gate; The change of the shear rate is not evidence from 1.5 mm to the end of part at flow direction, and the shear rate is 2000~4000s~(-1); the shear rate at the core layer is lowest, increases from the core layer to the sub-skin layer, and come to a maximum, and then decreases to the skin layer. However the shear rate at skin layer is higher than at core layer. The thinner the thickness of the parts, the greater the shear rate close to the gate, but the difference is not in evidence at the end.
     By utilizing simultane thermoanalyse (STA), the distribution rule of crystallinity along the flow direction and the thickness direction of thin-wall parts were researched. The results show the crystallinity close to the gate is higher than at other positions; the crystallinity decreases rapidly near the gate, and then gets to a nearly unconverted condition farther than 5 mm or so from the gate; The crystallinity close to the skin layer is higher than that at the core layer. The crystallinity increases from the skin to sub-skin layer and then decreases gradually to its minimum at the core layer; The melt temperature influences the crystallinity in thin-wall injection molding, which have little effect on the crystallinity at lower value, while higher melt temperature have more effect.
     According to the different crystallinity requirement of the performance, thin wall part's controllable fabrication can be realized by adjusting the melt temperature and injection velocity parameters so as to control the crystallinity of the forming part.
引文
[1]陈泰源.薄壳射出成形原理与应用.化工技术(台湾).2000,6(8):156-162
    [2]Chen Sh Ch,Peng H S,Huang L T,et al.Investigations of the tensile properties on polycarbonate thin-wall injection molded parts.Journal of reinforce plastics and composites,2003,22(5):479-453
    [3]Xu G X.Study of thin wall:injection molding:[博士学位论文].Ohio State:The Ohio State University,2004
    [4]Liao S J,Chang D Y,Chen H J et al.Optimal process conditions of shrinkage and warpage of thin-wall parts.Polymer engineer and science,2004,(5):78-83
    [5]宋满仓,颜克辉.薄壁注塑成型数值模拟技术的发展现状.塑料科技,2006,34(1):51-54
    [6]罗嗣胜,陈锋.塑料制品薄壁化技术.现代塑料加工应用,2004,16(4):37-39
    [7]宋满仓,刘柱,于同敏.注射工艺参数对超薄塑件成型影响实验研究.大连理工大学学报,2006,46(2):198-201
    [8]Jim F.Thin wall molding differences in processing over standard injection molding.SPEANTEC 1995,41:430-433
    [9]颜克辉.薄壁塑件注塑成型特性的试验与数值模拟研究:[硕士学位论文].大连:大连理工大学,2005
    [10]宋满仓,颜克辉,于同敏,等.薄壁注射成型数值模拟技术的现状与发展.模具制造,2006,(3):1-4
    [11]Yao D G,Kim B.Increasing flow length in thin wall injection molding using a rapidly heated mold.Polymer-plastics technology and engineering,2002,41(5):819-832
    [12]Losch K.Thin wall molding:demanding but rewarding.Modern plastics,1997,74(11):79-82
    [13]Maloney R P,Poslinski A J.Viscosity pressure dependence and material degradation effects on thin wall mold filling simulation.ANTEC,1998:542-546
    [14]Tantakom P,Nick R S.Processing strategies for thin wall injection molding.ANTEC,1998:367-371
    [15]Shen Y K,Yeh P H,Wu J S.Numerical simulation for thin wall injection molding of fiber-reinforced thermoplastics.International communications heat mass transfer,2002,29(3):423-431
    [16]Jansen K M B,Dijk D J V,Husselman.Effect of processing conditions on shrinkage in injection molding.Polymer engineering and science,1998,38(5):838-846
    [17]Shen Y K,Yeh P H,Wu J S.Numerical simulation for thin wall injection molding of fiber-reinforced thermoplastics.International communications in heat mass transfer,2001,28(8):1035-1042
    [18]Huang M Ch,Tai Ch Ch.The effective factors in the warpage problem of an injection-molded part with a thin shell feature.Materials processing technology,2001,110(1):1-9
    [19]Liao S J,Chang D Y,Chen H J,et al.Optimal process conditions of shrinkage and warpage of thin-wall parts.Polymer engineering and science,2004,44(5):917-928
    [20]宋满仓,颜克辉,赵丹阳.薄壁塑件注塑成形特性的试验研究.中国机械工程,2006,17(8):381-383
    [21]Poslinski A J.Effect processing conditions and material models on the injection pressure and flow length in thin wall parts.ANTEC,1996:470-474
    [22]Xu G X.Study of thin wall injection molding:[博士学位论文].Ohio State:The Ohio State University,2004
    [23]Chen Sh Ch,Peng H Sh,Huang L T,Chang Ch T,et al.Investigation on the mechanical properties of thin-wall injection molded parts.第24届高分子研讨会论文专辑,2002,133-134
    [24]谷诤巍,付沛福.薄壳成型技术.合成树脂及塑料,2001,18(5):57-60
    [25]焦剑,雷渭媛.高聚物结构、性能与测试.北京:化学工业出版社, 2003.39-124
    [26]Alexander L E.X-ray diffraction methods in polymer science,wiley-interscience,1969,London
    [27]翁灿.结晶型聚合物微注射成型性能研究:[硕士学位论文].长沙:中南大学,2006
    [28]Varga J.Super-moledular structure of isotactic polypropylene.Journal of material science,1992,27:2557-2479
    [29]D Fox M M,Weissberger A.Physics and chemistry of organic solid state,Wiley-intersicence,New York,1965
    [30]Yaughan A S,Bassett D C.Crystallization and morphology in comprehensive polymer science,Pergamon press,Oxford,1989
    [31]王兴天.注塑成型技术.北京:化学工业出版社,2001.406-411
    [32]傅强.聚烯烃注射成型--形态控制与性能.北京:科学出版社,2007.28-34
    [33]辛燕.等规聚苯乙烯单链/寡链和多链聚集体的结晶、结构和形态:[博士学位论文].浙江:浙江大学,2005
    [34]Zhao J,Mayes R H,Chen G,et al.Effects of process parameters on the micro molding process[J].Polymer Engineering and Science,2003,43(9):1542-1554
    [35]Nadkarni V M,Bulakh N N,Jog J P.Assessing polymer crystallizability from non-isothermal crystallization behavior.Advances in Polymer Technology,1993,12(1):73-79
    [36]Lorenzo L D,Silvestre C.Non-isothermal Crystallization of Polymers.Progress in Polymer Science,1999,24:917-950
    [37]Katti S S,Schultz J M.Microstructure of Injection-Molded Semicrystalline Polymers-a Review.Polymer Engineering and Science,1982,22(16):1001-1007
    [38]Chan T W,Isayev A I.Quiescent polymer crystallization:modeling and measurement.Polymer Engineering and Science,1994,34(6):461-471
    [39]Titomanlio G,Speranza V,Brucato.On the simulation of thermoplastic injection molding process:Ⅱ Relevance of interaction between flow and crystallization.International Polymer Processing, 1997, 12(1): 45—53
    
    [40] Huang T, Kamal R. Morphological modeling of polymers solidification, Polymer Engineering and Science, 2000, 40(8): 1796-1808
    
    [41] Hsiung C M, Cakmak M. Effect of injection-molding condition on the crystallinity, orientation gradient mechanical properties on poly (aryl-ether-ketone) ii : Large dumbbell parts. J. of Applied Polym. Sci., 1993, 47: 149—165
    
    [42] Zuidema H. Flow induced crystallization of polymer. [Ph.D Thesis]. University of Technology Eindhoven, the Netherlands, 2000
    
    [43] Guo J X. Numerical simulation of stress-induced crystallization of injection molded semicrystalline thermoplastics. [Ph. D Thesis]. New Jersey Institute of Technology, 2001
    
    [44] Martins J A, Zhang W, Carvalho V, et al. Evaluation of the sample temperature increase during the quiescent and shear-induced isothermal crystallization of polyethylene. Polymer, 2003, 44: 8071-8079
    
    [45] Zhang W, Martins J A. The temperature calibration of a parallel plate rheometer and evaluation of the thermal lags during polymer solidification. Thermochinica Acta., 2004, 413(1-2): 101-110
    
    [46] Nagatake W, Takahashi T, Masubuchi Y, et al. Development of shear flow thermal rheometer for direct measurement of crystallization fraction of polymer melts under shear deformation. Polymer, 2000, 41(2): 523—531
    
    [47] Masubuchi Y, Watanabe K, Nagatake W, et al. Thermal analysis of shear induced crystallization by the shear flow thermal rheometer: Isothermal crystallization of polypropylene. Polymer, 2001, 42(11): 5023-5027
    
    [48] Pogodina N V, Lavrenko V P, Srinivas S, et al. Rheology and structure of isotactic polypropylene near the gel point: Quiescent and shear-induced crystallization. Polymer, 2001, 42(11):9031-9043
    [49]Hieber C A.Modeling/Simulating the injection molding of isotactic polypropylene[J].Polymer Engineering and Science,2002,42(7):1387-1409
    [50]郑国强,王松杰.注射成型薄壁制品的结晶度.现代塑料的加工应用.2004,16(3):35-38
    [51]陶四平.高密度聚乙烯注塑成型冷却过程中温度分布及结晶行为的研究:[硕士学位论文].四川:四川大学,2005
    [52]Boping Xie,David I Bigio,ANTEC,1995:389
    [53]王文生,王旭霞.聚合物结晶度对注塑制品性能影响的研究.科技情报开发与经济.2002,12(3):115-117
    54]Liu Junyi,Dong Binbin.Et al.The study on crystallization of injection molded isotactic polypropylene.2006.第一届高聚物成型加工与材料物性预测国际学术研讨会论文集:158-162
    [55]Rong Zh,Peter K.Kennedy.Impact of flow on crystallization and impact of crystallization on flow in injection molding.2006,2006年第三届两岸三地先进成型技术与材料加工研讨会
    [56]Tribout C,Monasse B,Haudin J M.Colloid Polym Sci,1996,274:197
    [57]Somani R H,Hsiao B S,Nogales A,et al Macromolecules,2001,34:5902
    [58]Hsiung C M,Cakmark M.Effect of Injection-Molding condition on the crystallinity,Orientation Gradient,and Mechanical Properties on Poly(aryl-ether-ketone)Ⅱ:Large Dumbbell Parts.J.of Applied Polym.Sci.,1993,47:P149-165
    [59]何曼君、张红东、陈维孝,等.高分子物理.上海:复旦大学出版社,2006.182-186
    [60]Wang V W,Hieber C A,Wang K K.Dynamic simulation and graphics for the injection molding of three-dimensional thin parts.J.Polym.Engng,1986,7(1):21-45
    [61]王蕊.注塑成型三维流动模拟:[硕士学位论文].郑州:郑州大学,2004
    [62]申长雨等.塑料模具计算机辅助工程.郑州:河南科学技术出版社,1998: 34-41
    [63]LiYong Yu,Chee Cuan Koh,L,James Lee,et al.Experimental Investigation and Numerical Simulation of Injection Molding With Micro - Features.Polymer Engineering and Science,2002,42(5):871-888
    [64]Sang-Woo Kim,Lih-Sheng Turng.Developments of threedimensional computer -aided engineering simulation for injection moulding.Modeling and Simulation In Materials Science and Engineering,2004,12:151-173
    [65]刘春太,陈静波,董斌斌等.塑料注射成型保压过程的数值模拟.应用力学学报,2002,19(4):89-91
    [66]Hieber C A,Shen S F.A finite-element/ finite-difference simulation of injection molding filling process.J.Non-Newt.Fluid.Mech,1980,8:1-32
    [67]刘振海,徐国华,张洪林.热分析仪器.北京:化学工业出版社,2006.151-158
    [68]张世勋.聚合物结晶动力学参数测定及结晶度预测:[硕士学位论文].郑州:郑州大学,2003
    [69]郑融,Peter K.Impact of flow on crystallization and impact of crystallization on f10w in injection molding.2006,2006年第三届两岸三地先进成型技术与材料加工研讨会论文集:222-230

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址:北京市海淀区学院路29号 邮编:100083

电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700