随形冷却注塑模的设计与制造关键技术研究
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摘要
注塑成型是生产塑料制品最有效的方法之一,注塑模冷却系统的设计直接影响着注塑成型效率和最终制品的质量。较传统的注塑模冷却系统,随形冷却系统有冷却效率高、冷却均匀度好等优点。由于缺乏科学的设计理论与方法的指导,当前对随形冷却系统的设计仍然不得不采用传统的设计方法,致使设计效率低下,设计结果无法达到最优化。这已成为推广应用随形冷却技术的瓶颈。
本文在对随形冷却注塑模的传热过程进行理论分析和模拟研究的基础上,对该瞬态传热过程建立了详细准确的数学描述。该数学描述不但适用于圆形截面的冷却水道,还适用于椭圆截面、U形截面等非圆截面和一些特殊的冷却结构,具有广泛的适用性。
本文研究了基于选择性激光烧结(SLS)技术的注塑模快速制造工艺,通过实验的方法对随形冷却注塑模形坯可加工性问题进行了深入研究,并制定了相应的设计规则。
综合传热过程及可加工性问题研究的相关结论,根据注塑模随形冷却系统的特点,开发出了一套随形冷却系统的设计方法和设计规则。该方法基于区域冷却技术,以最佳型腔壁温度和最短冷却时间为目标,实现了设计结果的最优化。通过以香盒零件注塑模为研究对象的模拟及实物研究表明,内置随形冷却水道的注塑模,其生产效率提高了30%,由冷却不均匀引起的翘曲变形仅为普通模具的20%。最后,采用SLS快速制模工艺制作了金属注塑模具,并成功生产出了注塑件。
Injection molding is one of the most effictive techniques for plastic production. The design of the cooling system of injection molds directly affects both productivity and the quality of the final part. Compared with conventional drilled cooling channels, conformal cooling channels have demonstrated simultaneous improvements in cooling efficiency and cooling uniformity. However, because there is no methodology for the design of conformal cooling channels, designers have to use convetional methodology to design them. This is the major bottleneck for the application of conformal cooling system.
The transient heat-transfer process of the plastic injection molding is reaserched by the means of heat tranfer theory and numerial simulation software. On the base of those conclusions, the heat transfer mathematic model for conformal cooling is built. In this model, the shape factor is used to correct the calculate result. Not only is this heat transfer model suitable for the circule corss-section cooling channels, but also for other section shapes, such as ellipse, U shape etc.
The SLS rapid tooling technology is also studied. Green shape of injection mold with internal conformal cooling channels is formed using the composite metal powders developed in this work and optimal forming parameters. After decomposition, vacuum sintering,dropping infiltration of liquid bronze (or infiltration of epoxy and curing) and being simply machined, the mold can be used for plastic injection.
Conformal cooling system design methodology and design rules are developed after reaserching the features of the conformal cooling system. Some new concepts are used in this mehodology, such as cell cooling technology, minium cooling time and suitable temperature of cavity walls etc. By the guide of this methodology, designers can design optimal coformal cooling system efficiency. Finally, the injection mold of pomander with the designed optimal conformal cooling channels is fabricated by using the SLS technique. The production efficiency of the injection mold of pomander with conformal cooling channels is improved 30%, and the warpage is only 20% as much as the conventional injection mold.
本文在对随形冷却注塑模的传热过程进行理论分析和模拟研究的基础上,对该瞬态传热过程建立了详细准确的数学描述。该数学描述不但适用于圆形截面的冷却水道,还适用于椭圆截面、U形截面等非圆截面和一些特殊的冷却结构,具有广泛的适用性。
本文研究了基于选择性激光烧结(SLS)技术的注塑模快速制造工艺,通过实验的方法对随形冷却注塑模形坯可加工性问题进行了深入研究,并制定了相应的设计规则。
综合传热过程及可加工性问题研究的相关结论,根据注塑模随形冷却系统的特点,开发出了一套随形冷却系统的设计方法和设计规则。该方法基于区域冷却技术,以最佳型腔壁温度和最短冷却时间为目标,实现了设计结果的最优化。通过以香盒零件注塑模为研究对象的模拟及实物研究表明,内置随形冷却水道的注塑模,其生产效率提高了30%,由冷却不均匀引起的翘曲变形仅为普通模具的20%。最后,采用SLS快速制模工艺制作了金属注塑模具,并成功生产出了注塑件。
Injection molding is one of the most effictive techniques for plastic production. The design of the cooling system of injection molds directly affects both productivity and the quality of the final part. Compared with conventional drilled cooling channels, conformal cooling channels have demonstrated simultaneous improvements in cooling efficiency and cooling uniformity. However, because there is no methodology for the design of conformal cooling channels, designers have to use convetional methodology to design them. This is the major bottleneck for the application of conformal cooling system.
The transient heat-transfer process of the plastic injection molding is reaserched by the means of heat tranfer theory and numerial simulation software. On the base of those conclusions, the heat transfer mathematic model for conformal cooling is built. In this model, the shape factor is used to correct the calculate result. Not only is this heat transfer model suitable for the circule corss-section cooling channels, but also for other section shapes, such as ellipse, U shape etc.
The SLS rapid tooling technology is also studied. Green shape of injection mold with internal conformal cooling channels is formed using the composite metal powders developed in this work and optimal forming parameters. After decomposition, vacuum sintering,dropping infiltration of liquid bronze (or infiltration of epoxy and curing) and being simply machined, the mold can be used for plastic injection.
Conformal cooling system design methodology and design rules are developed after reaserching the features of the conformal cooling system. Some new concepts are used in this mehodology, such as cell cooling technology, minium cooling time and suitable temperature of cavity walls etc. By the guide of this methodology, designers can design optimal coformal cooling system efficiency. Finally, the injection mold of pomander with the designed optimal conformal cooling channels is fabricated by using the SLS technique. The production efficiency of the injection mold of pomander with conformal cooling channels is improved 30%, and the warpage is only 20% as much as the conventional injection mold.
引文
[1]王树勋,朱亚林,梅伶等.注塑模具设计[M].广州:华南理工大学出版社,2006.
[2]李海梅,申长雨.注塑成型及模具设计实用技术[M].北京:化学工业出版社,2002.
[3]张国强.注塑模设计与生产应用[M].北京:化学工业出版社,2005.
[4] LamontAS, CoreyJ. The Effects of Pulse Cooling on the Molding Cycle and Part Variation[C] //ANTEC2003 Annual Technical Conference Proceedings. Chicago, 2003:2857-2861
[5] TrinaRC, DouglasF. The Study of Process Stabilization and Consistency Using Pulse Cooling with a Terminator[C] //ANTEC2005 Annual Technical Conference Proceedings. Chicago, 2005:3387-3389.
[6] McCallaBA, AllanPS, HornsbyPR. Evaluation of Pulsed Cooling in Injection Mould Tools[C] //ANTEC2004, Annual Technical Conference Proceedings. Chicago, 2004:461-464.
[7] OweLarsson, AndyEdlund, WaltDemeres. The Toolvac Process– Cooling Injection Molds with CO2 Gas[C] //ANTEC1997 Annual Technical Conference Proceedings. Chicago,1997:1225-1229.
[8]李建钢.冷却注塑模具的最新解决方案[J].中国塑料,2006,24(4):57-58.
[9] Sachs.E., Eylonis,E.,Allen,s.,Ciam,M., Guo,H.and Brancazio,D. Progress on tooling by 3D printing: conformal cooling, dimensional control, surface finish and hardness[J]. In Proceeding of the 1997 Solid Freeform Fabrication Symposium, 1997:115-124.
[10] Jacobs, P.F. New frontiers in mold construction: high conductivity materials and conformal cooling channels [J]. Society of Manufacturing Engineers technical paper, 1999(10):99-115.
[11] Sachs,E., Eylonis,E.,Allen,s. Production of injection molding tooling with conformal cooling channels using the three dimension printing process[J]. Polymer Engineering and Science,2000,40:1232-1247.
[12] Dalgarno,K.W. and Stewart,T.D. Production tooling for polymer moulding using indirect SLS. Rapid Prototyping [J],2001,7:173-179.
[13] D.I.Wimpenny, B.Bryden, I.R.Pashby. Rapid laminated tooling. Journal of MaterialProcessing Technology[J], 2003,138:214-218.
[14] Ferreira J.C, Mateus A. Studies of rapid soft tooling with conformal cooling channels for plastic injection moulding[J]. Journal of Materials Processing Technology,2003,142(5):508-516.
[15] X.Xu. Conformal Cooling and Rapid Thermal Cycling in injection Molding by 3D Printed Tooling [D], Cambridge, Massachusetts:MIT, 1999.
[16] D.E. Dimla , M. Camilotto, F. Miani. Design and optimization of conformal cooling channels in injection moulding tools[J]. Journal of Materials Processing Technology, 2005, 164 :1294–1300.
[17] Kenny Dalgarno, Todd Stewart. Production tooling for polymer moulding using the Rapid Steel process [J]. Rapid Prototyping Journal, 2001, 7(3):173-179.
[18] Xiaorong Xu, Emanuel Sachs, Samuel Allen. The Design of conformal Cooling Channels in Injection Molding Tooling[J]. Polymer Engineering and Science. 2001,7(41):1265-1278.
[19] Dalgarno,K.W. and Stewart,T.D. Manufacture of production injection mould tooling incorporating conformal cooling channels via indirect selective laser sintering[J]. Proceedings of the Institution of Mechanical Engineers, 2001, 215(10):1323-1332.
[20] Fred G. S. New concepts in mold conformal cooling design[C]. In: Anon, ANTEC 2005-Annual Technical Conference proceedings, Volume 1:Processing, ANTEC 2005-Annual Technical Conference proceedings, Boston, 2005, Brookfield: Society of Plastics Engineers , 2005:916-920.
[21]史玉升,伍志刚,魏青松等随形冷却对注塑成型及生产效率的影响研究[J].华中科技大学学报(自然科学版),2007,35(3):60-62.
[22]伍志刚,史玉升,魏青松等注塑模新型冷却技术及其研究进展[J].中国机械工程,2006,17(增刊):161-165.
[23]龙桑田.快速制模技术[J].中国塑料,2006,24(4):50-54.
[24]张曙.快速制模与快速制造的新进展[J]. CAD/CAM与制造业信息化,2003,(7):95-98.
[25]洪慎章.快速成型技术是模具加工的创新[J]. 2004,42(2):54-56.
[26]莫建华.快速成形及快速制模[M].北京:电子工业出版社,2006.
[27]张渤涛,郝滨海,卢霄等.选择性激光烧结技术的特点及在模具制造中的应用[J].锻压技术,2005(3):7-9.
[28]王明娣,芮延年.快速成形技术在模具制造中的应用[J].苏州大学学报(工科版),2004,24(5):66-69.
[29]周广才,周顺亭,孙康等.激光成形金属零件技术在模具制造中的应用[J].模具技术,2004,(6):46-50.
[30]董祥忠,莫建华,史玉升等.基于快速制造新型注塑模具设计的探讨[J].工程塑料应用,2003,31(4):40-43.
[31]刘锦辉,史玉升,陈康华等.选择性激光烧结复合粉末法制造合金零件[J].华中科技大学学报(自然科学版),2006,34(5):83-85.
[32]刘锦辉,史玉升,王高潮等. SLS间接法制造金属零件生坯强度研究[J].华中科技大学学报(自然科学版),2006,34(3):54-57.
[33]鲁中良,史玉升,刘锦辉等.注塑模随形冷却水道设计与制造技术概述[J].中国机械工程2006,17(增刊):165-170.
[34]樊自田,黄乃瑜,陈宗孟.基于选择性激光烧结技术的快速铸造[J].特种铸造及有色合金,1999,(5):7-9.
[35]马天,邢建东,方亮等.采用快速原型树脂模铸造精密模具[J].西安交通大学学报,2001,35(3):292-297.
[36]颜永年,单忠德.快速成形与铸造技术[M].北京:机械工业出版社,2004.
[37]姜不居.熔模精密铸造[M].北京:机械工业出版社,2004.
[38]孙琨,王伊卿,卢秉恒.基于RP的快速金属模具制造精度控制研究[J].中国机械工程,2001,13(1):60-63.
[39]张沛,陈家庆.注塑模温控系统的设计计算[J].模具工业,2001,(2):37-41.
[40]唐志玉,李德群,徐佩弦.塑料模具设计师指南[M].北京:国防工业出版社.1999.
[41]包荣华.塑料注射模冷却系统的设计[J].模具制造,2003(7):42 46.
[42]杨扬,董斌斌,刘春太.成型温度对纤维增强注塑熔接线拉伸性能的影响[J].郑州大学学报(工学版),200425(1):102-105.
[43]苏开华,陈锋.精密注塑成型中温度对制品收缩率的影响[J].广东塑料,2005(4):25-29.
[44]周志明.模温状态对注塑制品质量的影响分析[J].三明职业大学学报,2000(3):110-115.
[45]郭建平,黄步明.塑料注塑加工中结晶与取向的探讨[J].工程塑料应用,2003,31(10):25-28.
[46]李惠元.影响聚砜制品表面质量的原因分析和预防措施[J].工程塑料应用,2004,32(2):24-26.
[47]吴利英.影响注塑件内应力的因素[J].工程塑料应用,2004,32(10):28-31.
[48]张友根.影响注塑制品重量重复精度因素分析研究[J].现代塑料加工应用,2004,16(3):39-41.
[49] MingChih Huang ,ChingChih Tai. The effective factors in the warpage problem of an injection-molded part with a thin shell feature[J]. Journal of Materials Processing Technology,2001,110(2):1-9.
[50]李永梅,林彬,李延杰.塑料注塑模具冷却系统的设计[J].工程塑料应用,2006,34(4):48-50.
[51]平学成,马健萍.注塑模具瞬态温度仿真研究[J].机械,2005,32(2):6-10.
[52] Yuwan Lin, Haimei Li, Shiachung Chen. 3Dnumerical simulation of transient temperature field for lens mold embedded with heaters [J]. International Communications in Heat and Mass Transfer, 2005,(32)7:1221-123.
[53] Amit Kumar, P.S. Ghoshdastidar, M.K.Muju. Computer simulation of transport processes during injection mold-filling and optimization of the molding conditions [J]. Journal of materials processing technology, 2002,120: 438-449.
[54] H. Qiao. Transient mold cooling analysis using BEM with the time-dependent fundamental solution[J]. International communications in heat and mass transfer. 2005,32:315-322.
[55]崔树标.注塑模冷却过程数值模拟技术研究[D].武汉:华中科技大学图书馆,2005.
[56] J. Fay. Intorduction to Fluid Mechanics[M]. Massachusetts : MIT Press,1995.
[57]杨世铭,陶文铨.传热学[M].北京:高等教育出版社.1998.
[58]申开智,付晓蓉.以最佳型壁温度为目标优化注塑模冷却系统设计[J].中国塑料,2003,17(11):48-52.
[59] Weidan Liu, Tom Kimerling, Byung Kim. Rapid thermal response mold design[C] //ANTEC2005 Annual Technical Conference Proceedings. Chicago, 2005:956-960
[60]陈青葵.注塑成型[M].北京:化学工业出版社,2007.
[61]黄华山.塑料注塑技术与实例[M].北京:化学工业出版社,2006.
[62]王安强等.材料力学[M].西安:西北工业大学出版社,2002.
[63]范钦珊.工程力学[M].北京:机械工业出版社,2006.
[2]李海梅,申长雨.注塑成型及模具设计实用技术[M].北京:化学工业出版社,2002.
[3]张国强.注塑模设计与生产应用[M].北京:化学工业出版社,2005.
[4] LamontAS, CoreyJ. The Effects of Pulse Cooling on the Molding Cycle and Part Variation[C] //ANTEC2003 Annual Technical Conference Proceedings. Chicago, 2003:2857-2861
[5] TrinaRC, DouglasF. The Study of Process Stabilization and Consistency Using Pulse Cooling with a Terminator[C] //ANTEC2005 Annual Technical Conference Proceedings. Chicago, 2005:3387-3389.
[6] McCallaBA, AllanPS, HornsbyPR. Evaluation of Pulsed Cooling in Injection Mould Tools[C] //ANTEC2004, Annual Technical Conference Proceedings. Chicago, 2004:461-464.
[7] OweLarsson, AndyEdlund, WaltDemeres. The Toolvac Process– Cooling Injection Molds with CO2 Gas[C] //ANTEC1997 Annual Technical Conference Proceedings. Chicago,1997:1225-1229.
[8]李建钢.冷却注塑模具的最新解决方案[J].中国塑料,2006,24(4):57-58.
[9] Sachs.E., Eylonis,E.,Allen,s.,Ciam,M., Guo,H.and Brancazio,D. Progress on tooling by 3D printing: conformal cooling, dimensional control, surface finish and hardness[J]. In Proceeding of the 1997 Solid Freeform Fabrication Symposium, 1997:115-124.
[10] Jacobs, P.F. New frontiers in mold construction: high conductivity materials and conformal cooling channels [J]. Society of Manufacturing Engineers technical paper, 1999(10):99-115.
[11] Sachs,E., Eylonis,E.,Allen,s. Production of injection molding tooling with conformal cooling channels using the three dimension printing process[J]. Polymer Engineering and Science,2000,40:1232-1247.
[12] Dalgarno,K.W. and Stewart,T.D. Production tooling for polymer moulding using indirect SLS. Rapid Prototyping [J],2001,7:173-179.
[13] D.I.Wimpenny, B.Bryden, I.R.Pashby. Rapid laminated tooling. Journal of MaterialProcessing Technology[J], 2003,138:214-218.
[14] Ferreira J.C, Mateus A. Studies of rapid soft tooling with conformal cooling channels for plastic injection moulding[J]. Journal of Materials Processing Technology,2003,142(5):508-516.
[15] X.Xu. Conformal Cooling and Rapid Thermal Cycling in injection Molding by 3D Printed Tooling [D], Cambridge, Massachusetts:MIT, 1999.
[16] D.E. Dimla , M. Camilotto, F. Miani. Design and optimization of conformal cooling channels in injection moulding tools[J]. Journal of Materials Processing Technology, 2005, 164 :1294–1300.
[17] Kenny Dalgarno, Todd Stewart. Production tooling for polymer moulding using the Rapid Steel process [J]. Rapid Prototyping Journal, 2001, 7(3):173-179.
[18] Xiaorong Xu, Emanuel Sachs, Samuel Allen. The Design of conformal Cooling Channels in Injection Molding Tooling[J]. Polymer Engineering and Science. 2001,7(41):1265-1278.
[19] Dalgarno,K.W. and Stewart,T.D. Manufacture of production injection mould tooling incorporating conformal cooling channels via indirect selective laser sintering[J]. Proceedings of the Institution of Mechanical Engineers, 2001, 215(10):1323-1332.
[20] Fred G. S. New concepts in mold conformal cooling design[C]. In: Anon, ANTEC 2005-Annual Technical Conference proceedings, Volume 1:Processing, ANTEC 2005-Annual Technical Conference proceedings, Boston, 2005, Brookfield: Society of Plastics Engineers , 2005:916-920.
[21]史玉升,伍志刚,魏青松等随形冷却对注塑成型及生产效率的影响研究[J].华中科技大学学报(自然科学版),2007,35(3):60-62.
[22]伍志刚,史玉升,魏青松等注塑模新型冷却技术及其研究进展[J].中国机械工程,2006,17(增刊):161-165.
[23]龙桑田.快速制模技术[J].中国塑料,2006,24(4):50-54.
[24]张曙.快速制模与快速制造的新进展[J]. CAD/CAM与制造业信息化,2003,(7):95-98.
[25]洪慎章.快速成型技术是模具加工的创新[J]. 2004,42(2):54-56.
[26]莫建华.快速成形及快速制模[M].北京:电子工业出版社,2006.
[27]张渤涛,郝滨海,卢霄等.选择性激光烧结技术的特点及在模具制造中的应用[J].锻压技术,2005(3):7-9.
[28]王明娣,芮延年.快速成形技术在模具制造中的应用[J].苏州大学学报(工科版),2004,24(5):66-69.
[29]周广才,周顺亭,孙康等.激光成形金属零件技术在模具制造中的应用[J].模具技术,2004,(6):46-50.
[30]董祥忠,莫建华,史玉升等.基于快速制造新型注塑模具设计的探讨[J].工程塑料应用,2003,31(4):40-43.
[31]刘锦辉,史玉升,陈康华等.选择性激光烧结复合粉末法制造合金零件[J].华中科技大学学报(自然科学版),2006,34(5):83-85.
[32]刘锦辉,史玉升,王高潮等. SLS间接法制造金属零件生坯强度研究[J].华中科技大学学报(自然科学版),2006,34(3):54-57.
[33]鲁中良,史玉升,刘锦辉等.注塑模随形冷却水道设计与制造技术概述[J].中国机械工程2006,17(增刊):165-170.
[34]樊自田,黄乃瑜,陈宗孟.基于选择性激光烧结技术的快速铸造[J].特种铸造及有色合金,1999,(5):7-9.
[35]马天,邢建东,方亮等.采用快速原型树脂模铸造精密模具[J].西安交通大学学报,2001,35(3):292-297.
[36]颜永年,单忠德.快速成形与铸造技术[M].北京:机械工业出版社,2004.
[37]姜不居.熔模精密铸造[M].北京:机械工业出版社,2004.
[38]孙琨,王伊卿,卢秉恒.基于RP的快速金属模具制造精度控制研究[J].中国机械工程,2001,13(1):60-63.
[39]张沛,陈家庆.注塑模温控系统的设计计算[J].模具工业,2001,(2):37-41.
[40]唐志玉,李德群,徐佩弦.塑料模具设计师指南[M].北京:国防工业出版社.1999.
[41]包荣华.塑料注射模冷却系统的设计[J].模具制造,2003(7):42 46.
[42]杨扬,董斌斌,刘春太.成型温度对纤维增强注塑熔接线拉伸性能的影响[J].郑州大学学报(工学版),200425(1):102-105.
[43]苏开华,陈锋.精密注塑成型中温度对制品收缩率的影响[J].广东塑料,2005(4):25-29.
[44]周志明.模温状态对注塑制品质量的影响分析[J].三明职业大学学报,2000(3):110-115.
[45]郭建平,黄步明.塑料注塑加工中结晶与取向的探讨[J].工程塑料应用,2003,31(10):25-28.
[46]李惠元.影响聚砜制品表面质量的原因分析和预防措施[J].工程塑料应用,2004,32(2):24-26.
[47]吴利英.影响注塑件内应力的因素[J].工程塑料应用,2004,32(10):28-31.
[48]张友根.影响注塑制品重量重复精度因素分析研究[J].现代塑料加工应用,2004,16(3):39-41.
[49] MingChih Huang ,ChingChih Tai. The effective factors in the warpage problem of an injection-molded part with a thin shell feature[J]. Journal of Materials Processing Technology,2001,110(2):1-9.
[50]李永梅,林彬,李延杰.塑料注塑模具冷却系统的设计[J].工程塑料应用,2006,34(4):48-50.
[51]平学成,马健萍.注塑模具瞬态温度仿真研究[J].机械,2005,32(2):6-10.
[52] Yuwan Lin, Haimei Li, Shiachung Chen. 3Dnumerical simulation of transient temperature field for lens mold embedded with heaters [J]. International Communications in Heat and Mass Transfer, 2005,(32)7:1221-123.
[53] Amit Kumar, P.S. Ghoshdastidar, M.K.Muju. Computer simulation of transport processes during injection mold-filling and optimization of the molding conditions [J]. Journal of materials processing technology, 2002,120: 438-449.
[54] H. Qiao. Transient mold cooling analysis using BEM with the time-dependent fundamental solution[J]. International communications in heat and mass transfer. 2005,32:315-322.
[55]崔树标.注塑模冷却过程数值模拟技术研究[D].武汉:华中科技大学图书馆,2005.
[56] J. Fay. Intorduction to Fluid Mechanics[M]. Massachusetts : MIT Press,1995.
[57]杨世铭,陶文铨.传热学[M].北京:高等教育出版社.1998.
[58]申开智,付晓蓉.以最佳型壁温度为目标优化注塑模冷却系统设计[J].中国塑料,2003,17(11):48-52.
[59] Weidan Liu, Tom Kimerling, Byung Kim. Rapid thermal response mold design[C] //ANTEC2005 Annual Technical Conference Proceedings. Chicago, 2005:956-960
[60]陈青葵.注塑成型[M].北京:化学工业出版社,2007.
[61]黄华山.塑料注塑技术与实例[M].北京:化学工业出版社,2006.
[62]王安强等.材料力学[M].西安:西北工业大学出版社,2002.
[63]范钦珊.工程力学[M].北京:机械工业出版社,2006.