MIM充模流动3D计算机模拟
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摘要
本论文在详细分析了金属粉末注射成形(Metal Injection Molding，简称MIM)充模机理的基础上，假定喂料熔体为混合均匀、不可压缩的非牛顿流体，充模流动为层流，依据流体力学和热力学知识，结合实验结果，采用欧拉法列出了完整的求解方程，并给出了相应的边界条件。同时在此基础上，数学分析了采用有限元方法的求解过程，并利用有限元分析软件ANSYS中的FLOTRAN模块实现了MIM的充模流动的3D模拟求解。
利用ANSYS提供的二次开发功能，修正了FLOTRAN提供的简化了的幂律模型语句，加入温度项参数，重新编译该模块并基于新生成的模块进行充模模拟。
以硬质合金Ⅰ型拉伸试样为例，结合3D技术，模拟了MIM喂料在简单几何模腔的流动情况，利用ANSYS提供的Z-Buffer切片模型空间观测方式，讨论了浇口位置、浇口大小和模壁温度等主要工艺参数对熔体充模过程的影响，预测注射成形过程中部分常见缺陷产生的条件。模拟结：果表明：当采用大小为4×1mm~2的侧面浇口、模温320K、注射温度400K以及体积流速60cm~3／s的注射参数进行注射时可以得到良好无缺陷的硬质合金Ⅰ型拉伸试样预成形坯。
结合实际生产情况，进一步选取形状复杂的支持块模腔进行3D充模模拟，根据模拟结果，预测实际制品缺陷产生的部位并分析了缺陷形成机理。最后依据模拟结果，推荐采用INLET4位置浇口进行注射生产，实验表明制得的支持块无缺陷，产品通过了有关部门的验收，证明了充模流动3D模拟的可行性和准确性，同时展示了3D充模模拟技术在指导工艺参数优化方面的广阔前景。
In this paper, the control equations, initial and boundary conditions for the mold filling process are proposed, by assuming that feedstock melt is non-Newtonian and incompressible continuum-flow on the basis of analyzing the mold filling process of metal injection molding, and of the theories of hydromechanics and thermodynamics. According to the above, the paper uses the finite element analysis software -ANSYS to solve the equations and realize the 3D computer simulation of the mold filling process.
The simplified Power-Law viscosity model in FLOTRAN was rectified and re-compiled by taking advantage of the second development function of ANSYS and temperature parameter was added. The new model, which is proved to be correct by the experiments, was used to perform all the 3D computer simulation.
Take cemented carbide I part for example. By employing the Z-Buffer section of ANSYS, the paper illustrates the 3D simulation of cemented carbide feedstock filling simple cavity, discusses the effects of the inlets position, inlets size, wall temperature and predicts the conditions for some defects which often appear in the process of the metal powder injection molding .The results show that good green compacts of cemented carbide could be made if the volume flow velocity is selected 60cm3/s when the wall temperature and the injection temperature are set at 300K and 400K respectively with lateral injecting inlet in size of 4 x1 mm2, which was proved by the experiments.
What is more, the paper also illustrates the 3D simulation of the process of filling a complicate cavity, the positions of defects are predicted and mechanism is discussed. Prior to the practical production, the die filling behavior of new inlets were simulated. Finally, the paper recommends the INLET4 as the optimal injection position. Good products that have passed through the acceptance check of relative department are made according to the simulation results. At the same time, the paper brings forth the applied prospect of the 3D simulation of the die filling process.
利用ANSYS提供的二次开发功能，修正了FLOTRAN提供的简化了的幂律模型语句，加入温度项参数，重新编译该模块并基于新生成的模块进行充模模拟。
以硬质合金Ⅰ型拉伸试样为例，结合3D技术，模拟了MIM喂料在简单几何模腔的流动情况，利用ANSYS提供的Z-Buffer切片模型空间观测方式，讨论了浇口位置、浇口大小和模壁温度等主要工艺参数对熔体充模过程的影响，预测注射成形过程中部分常见缺陷产生的条件。模拟结：果表明：当采用大小为4×1mm~2的侧面浇口、模温320K、注射温度400K以及体积流速60cm~3／s的注射参数进行注射时可以得到良好无缺陷的硬质合金Ⅰ型拉伸试样预成形坯。
结合实际生产情况，进一步选取形状复杂的支持块模腔进行3D充模模拟，根据模拟结果，预测实际制品缺陷产生的部位并分析了缺陷形成机理。最后依据模拟结果，推荐采用INLET4位置浇口进行注射生产，实验表明制得的支持块无缺陷，产品通过了有关部门的验收，证明了充模流动3D模拟的可行性和准确性，同时展示了3D充模模拟技术在指导工艺参数优化方面的广阔前景。
In this paper, the control equations, initial and boundary conditions for the mold filling process are proposed, by assuming that feedstock melt is non-Newtonian and incompressible continuum-flow on the basis of analyzing the mold filling process of metal injection molding, and of the theories of hydromechanics and thermodynamics. According to the above, the paper uses the finite element analysis software -ANSYS to solve the equations and realize the 3D computer simulation of the mold filling process.
The simplified Power-Law viscosity model in FLOTRAN was rectified and re-compiled by taking advantage of the second development function of ANSYS and temperature parameter was added. The new model, which is proved to be correct by the experiments, was used to perform all the 3D computer simulation.
Take cemented carbide I part for example. By employing the Z-Buffer section of ANSYS, the paper illustrates the 3D simulation of cemented carbide feedstock filling simple cavity, discusses the effects of the inlets position, inlets size, wall temperature and predicts the conditions for some defects which often appear in the process of the metal powder injection molding .The results show that good green compacts of cemented carbide could be made if the volume flow velocity is selected 60cm3/s when the wall temperature and the injection temperature are set at 300K and 400K respectively with lateral injecting inlet in size of 4 x1 mm2, which was proved by the experiments.
What is more, the paper also illustrates the 3D simulation of the process of filling a complicate cavity, the positions of defects are predicted and mechanism is discussed. Prior to the practical production, the die filling behavior of new inlets were simulated. Finally, the paper recommends the INLET4 as the optimal injection position. Good products that have passed through the acceptance check of relative department are made according to the simulation results. At the same time, the paper brings forth the applied prospect of the 3D simulation of the die filling process.
引文
[1] 曹勇家．金属注射成形发展的机遇和挑战．粉末冶金工业，2001，11(3)：7
[2] R.M. German. A Vision of PIM Industry-Yesterday, Today and Tomorrow. Proc of PIM98,1998,3-26
[3] R.M. German. Powder Injection Molding. Metal Powder Industries Federation, Princeton, N. J, 1991
[4] J. E Stevenson. A. Galskoy, K. K. Wang, I. Chen and D. H. Reber. Injection Molding in Disk-Shaped Cavities. Polym. Eng. Sci., 1997, 17(9)
[51 R.M. German. A Review of Numerical and Computational Techniques in Powder Metallurgy, Advances in Powder Metallurgy and Particulate Materials, 1993, 3: 1-12
[6] 李益民，黄伯云．工艺参数对金属注射成形坯缺陷的影响．稀有金属材料与工程，1999，28(2)：117
[7] 敖晖，李晓明，曲选辉，黄伯云．充模流动计算机模拟在硬质合金MIM中的应用．硬质合金，2001，18(4)：1997-2000
[8] 梁叔全，黄伯云．粉末注射成形流变学．长沙：中南大学出版社，2000
[9] H.L. Toor, R. L. Ballman and L. Cooper. Predicting Mold Flow by Electronic Computer. Mod. Plast., 39: 117～209
[10] M.R. Kamal and S. Kenig. The Injection Molding of Thermoplastics. Polym. Eng. Sci., 1972, 12: 295～308
[11] I. Tadmor, E. Broyer and C. Gutfinger. Flow Analysis Network-A Method for Solving Flow Problems in Polymer Process. Polym. Eng. Sci., 1974,14: 660～665
[12] C. A. Hieber and S. F. Shen. Flow Analysis of the Non-Isothermal Two-Dimensional Filling Process in Injection Molding. Israel Journal of Technology, 1978, 16: 248～254
[13] C.A. Hieber and S. F. Shen. A Finite-Element/Finite-Difference Simulation of the Injection Molding Filling Process. Journal of Non-Newtonian Fluid Mechanics, 1980, 7: 1～32
[14] V.W. Wang and C. A. Hieber. Mold-Filling-Simulation in Injection Molding of Three-Dimensional Thin Parts. Annual Technical Conference - Society of Plastics Engineers, 1986, 97～102
[15] H. Zhou and D. Li. A Numerical Simulation of the Filling Stage in Injection Molding Based on Surface Model. Advances in Polymer Technology, 2001, 20(2): 125～131
[16] A. Liaqust, Najmi and Daeyong Lee. Application of Mold Filling simulation to Powder Injection Molding. The International Journal of Powder Metallurgy, 1994, 30(2): 231
[17] Liaquat, Ali Najmi and Daeyong Lee. Modeling of Mold Filling Process for Powder Injection Molding. Polym. Eng. Sci., 1991, 31(5): 1137
[18] C.M. Wang, R. L. Leonard et al. Prediction of Defect Formation in Powder Injection Molding by Computer Simulation. Proceedings of the 3rd International Conference on Powder Metallurgy in Aerospace. Defense and Demanding Applications, 1993, 85～92
[19] Tai Hun Kwon, Chul Jin Hwang and Jun Ho Rhee. Numerical Simulation of Powder Injection Molding Filling Process for Three-Dimensional Complicated Cavity Geometries. Advances in Powder Metallurgy. & Particulate Mataerials- 1996, MPIF, 1996, 5: 19
[20] K.E. Carr. PIM Analysis and Design Tools: Computer Simulation Code and Knowledge Based Expert System. Advances in Powder Metallurgy and Particulate Materials, 1995, 6: 279～286
[21] I. Pandelidis and Q. Zou. Optimization of Injection Molding Design, Part Ⅰ: Gate Location Optimization. Polym. Eng. Sci., 1990, 30(15): 873
[22] L. A. Najmi and D. Lee. Application of Mold Filling Simulation to Gate Location Optimization in Powder Injection Molding. Advance in Powder Metallurgy, MPIF, APMI, 1991,1: 95
[23] Byung-ohk Rhee and Jung-hwan Lee. Investigation of the Gate Effect on the Powder Injection Molding Process. Proceeding of 2000 Powder Metallurgy World Congress, 2000: 278～281
[24] I. Pandelidis and Q. Zou. Optimization of Injection Molding Design, Part Ⅱ: Molding Conditions Optimization. Polym. Eng. Sci, 1990, 30(15): 883
[25] C.M. Wang. A Finite-Different Computing Model for 3-D Simulation of the Powder Injection Molding Process. Powder Injection Molding Symposium, 1992, 435～448
[26] C.M. Wang. Computation Analysis of Fluid Flow and Heat Transfer in the Powder Injection Molding Process. Advance in Powder Metallurgy &
Particular Materials, 1993, 5: 31～37
[27] K. H. Tan and M. M. F. Yuen. Fuzzy Multiobjective Approach for Minimization of Injection Molding Defects. Polymer Engineering and Science, 2000, 40(4): 956～971
[28] S. Kihara, T. Gouda. Numerical Simulation of Three-Dimensional Viscoelastic Flow within Dies. Polymer Engineering and Science, 1999, 39(1): 152
[29] T. H. Kwon. Finite Element Analysis of PIM Filling Process with Slip Characterization of Powder-Binder Mixtures. Powder Metallurgy, 1997,40(3): 174～176
[30] T. Iwai, T. Aizawa and Kihara. Three Dimensional Granular Molding for Metal Injection Molding. Powder Metallurgy'94, Metal Injection Molding, 1994: 1097
[31] T. Iwai, T. Aizawa and Kihara. Powder-Binder Flow Simulation in Powder Injection Molding. Advances in Powder Metallurgy and Particular Materials, 1996, 5:19
[32] 乐红胜．粉末注射成形充模流动及冷却凝固过程计算机模拟．硕士学位论文，长沙：中南工业大学，1997
[33] 毛金英．粉末注射成形二维充模流动计算机模拟．硕士学位论文，长沙：中南工业大学，1999
[34] 林好转．金属粉末注射成形的喂料性能及成形的模具研究．博士后研究工作报告，长沙：中南工业大学，1998
[35] 曲选辉，温宏宇，敖晖，郑洲顺．粉末注射成形过程计算机模拟研究．材料工程，2001，6：33～36
[36] 曲选辉，温宏宇．粉末注射成形技术及其应用．2000年材料科学与工程新进展(上)，北京：冶金工业出版社，2001：18-22
[37] 李德群．注塑模CAD／CAE／CAM发展综述．模具工业，1996，7(1)：4
[38] 张佑生．塑料模具计算机辅助设计．机械工业出版社，1999
[39] 陈静波，刘春太，王丽霞，申长雨．注射模Z-MOLD软件的开发与应用．模具工业，1997，11：9-12
[40] C. J. Hwang. Computer-Aided Engineering System for Powder Injection Molding Filling Process. PIM 2000 World Congress
[41] 毛金英，曲选辉，乐红胜，林好转，李益民．粉末注射成形充模过程中凝固层形成规律的计算与分析．粉末冶金技术，1999，17(1)：14
[42] B. H. Rosof The Metal Injection Molding Process Comes of Age. J. of Mater., 1989, 41(8): 13～16
[43] 汪宏俊．流体力学，北京：高等教育出版社，1988
[44] R．M．German著，曲选辉等译．粉末注射成形，中南大学出版社，2001
[45] O.A. Novac, D. Anton and T. Novac. The Rheological Behavior of Some Binders and Plastics Used in Injection Molding. Powder Metallurgy 94, 1994: 113
[46] Florin Ilinca. Metal Injection Molding: Simulation of Three-Dimensional Flow with Free Surface Boundary and Experimental Comparison. ANTEC 2000: 718
[47] V.V. Bilovol, L. Kowalski and J. Duszxzyk. Modeling of Transient TemperatureFields during Filling Stage of Powder Injection Molding. Powder Metallurgy, 2000, 43(3): 228～232
[48] 王成，邵敏．有限单元法基本原理和数值方法．第二版，清华大学出版社，1997
[49] 章本照．流体力学中的有限元法．机械工业出版社，1986
[50] 方丁酉．两相流动力学．长沙：国防科技大学出版社，1988
[51] S．S劳尔[美]，傅子智译．工程中的有限元法．科学出版社，1991
[52] ANSYS分析指南．美国ANSYS公司出版，2002
[53] 谭建国．使用ANSYS 6.0进行有限元分析，北京大学出版社，2002
[54] 王国强．实用工程数值模拟技术及其在ANSYS上的实践，西北工业大学出版社：1999
[55] ANSYS流体动力学分析培训手册．美国ANSYS公司北京办事处
[56] K. M. Pillai, C. L. Tucker and E R. Phelan. Numerical Simulation of Injection/Compression Liquid Composite Molding. Part Ⅰ: Mesh Generation, Composite, Part A: Applied Science and Manufacturing, 2000, 31: 87～94
[57] 祝宝军等．YG8硬质合金注射成形技术．第八届材料科学与合金加工学术年会论文集，2000，11
[58] 史安娜，王晓方．盒形塑料浇口位置的选择．模具工业，2000，4，31
[59] 宋满仓，赵丹阳，于同敏，刘莹．基于CAE分析的PP-R管件熔接痕消除方法．中国塑料，2001，15(8)：62-65
[2] R.M. German. A Vision of PIM Industry-Yesterday, Today and Tomorrow. Proc of PIM98,1998,3-26
[3] R.M. German. Powder Injection Molding. Metal Powder Industries Federation, Princeton, N. J, 1991
[4] J. E Stevenson. A. Galskoy, K. K. Wang, I. Chen and D. H. Reber. Injection Molding in Disk-Shaped Cavities. Polym. Eng. Sci., 1997, 17(9)
[51 R.M. German. A Review of Numerical and Computational Techniques in Powder Metallurgy, Advances in Powder Metallurgy and Particulate Materials, 1993, 3: 1-12
[6] 李益民，黄伯云．工艺参数对金属注射成形坯缺陷的影响．稀有金属材料与工程，1999，28(2)：117
[7] 敖晖，李晓明，曲选辉，黄伯云．充模流动计算机模拟在硬质合金MIM中的应用．硬质合金，2001，18(4)：1997-2000
[8] 梁叔全，黄伯云．粉末注射成形流变学．长沙：中南大学出版社，2000
[9] H.L. Toor, R. L. Ballman and L. Cooper. Predicting Mold Flow by Electronic Computer. Mod. Plast., 39: 117～209
[10] M.R. Kamal and S. Kenig. The Injection Molding of Thermoplastics. Polym. Eng. Sci., 1972, 12: 295～308
[11] I. Tadmor, E. Broyer and C. Gutfinger. Flow Analysis Network-A Method for Solving Flow Problems in Polymer Process. Polym. Eng. Sci., 1974,14: 660～665
[12] C. A. Hieber and S. F. Shen. Flow Analysis of the Non-Isothermal Two-Dimensional Filling Process in Injection Molding. Israel Journal of Technology, 1978, 16: 248～254
[13] C.A. Hieber and S. F. Shen. A Finite-Element/Finite-Difference Simulation of the Injection Molding Filling Process. Journal of Non-Newtonian Fluid Mechanics, 1980, 7: 1～32
[14] V.W. Wang and C. A. Hieber. Mold-Filling-Simulation in Injection Molding of Three-Dimensional Thin Parts. Annual Technical Conference - Society of Plastics Engineers, 1986, 97～102
[15] H. Zhou and D. Li. A Numerical Simulation of the Filling Stage in Injection Molding Based on Surface Model. Advances in Polymer Technology, 2001, 20(2): 125～131
[16] A. Liaqust, Najmi and Daeyong Lee. Application of Mold Filling simulation to Powder Injection Molding. The International Journal of Powder Metallurgy, 1994, 30(2): 231
[17] Liaquat, Ali Najmi and Daeyong Lee. Modeling of Mold Filling Process for Powder Injection Molding. Polym. Eng. Sci., 1991, 31(5): 1137
[18] C.M. Wang, R. L. Leonard et al. Prediction of Defect Formation in Powder Injection Molding by Computer Simulation. Proceedings of the 3rd International Conference on Powder Metallurgy in Aerospace. Defense and Demanding Applications, 1993, 85～92
[19] Tai Hun Kwon, Chul Jin Hwang and Jun Ho Rhee. Numerical Simulation of Powder Injection Molding Filling Process for Three-Dimensional Complicated Cavity Geometries. Advances in Powder Metallurgy. & Particulate Mataerials- 1996, MPIF, 1996, 5: 19
[20] K.E. Carr. PIM Analysis and Design Tools: Computer Simulation Code and Knowledge Based Expert System. Advances in Powder Metallurgy and Particulate Materials, 1995, 6: 279～286
[21] I. Pandelidis and Q. Zou. Optimization of Injection Molding Design, Part Ⅰ: Gate Location Optimization. Polym. Eng. Sci., 1990, 30(15): 873
[22] L. A. Najmi and D. Lee. Application of Mold Filling Simulation to Gate Location Optimization in Powder Injection Molding. Advance in Powder Metallurgy, MPIF, APMI, 1991,1: 95
[23] Byung-ohk Rhee and Jung-hwan Lee. Investigation of the Gate Effect on the Powder Injection Molding Process. Proceeding of 2000 Powder Metallurgy World Congress, 2000: 278～281
[24] I. Pandelidis and Q. Zou. Optimization of Injection Molding Design, Part Ⅱ: Molding Conditions Optimization. Polym. Eng. Sci, 1990, 30(15): 883
[25] C.M. Wang. A Finite-Different Computing Model for 3-D Simulation of the Powder Injection Molding Process. Powder Injection Molding Symposium, 1992, 435～448
[26] C.M. Wang. Computation Analysis of Fluid Flow and Heat Transfer in the Powder Injection Molding Process. Advance in Powder Metallurgy &
Particular Materials, 1993, 5: 31～37
[27] K. H. Tan and M. M. F. Yuen. Fuzzy Multiobjective Approach for Minimization of Injection Molding Defects. Polymer Engineering and Science, 2000, 40(4): 956～971
[28] S. Kihara, T. Gouda. Numerical Simulation of Three-Dimensional Viscoelastic Flow within Dies. Polymer Engineering and Science, 1999, 39(1): 152
[29] T. H. Kwon. Finite Element Analysis of PIM Filling Process with Slip Characterization of Powder-Binder Mixtures. Powder Metallurgy, 1997,40(3): 174～176
[30] T. Iwai, T. Aizawa and Kihara. Three Dimensional Granular Molding for Metal Injection Molding. Powder Metallurgy'94, Metal Injection Molding, 1994: 1097
[31] T. Iwai, T. Aizawa and Kihara. Powder-Binder Flow Simulation in Powder Injection Molding. Advances in Powder Metallurgy and Particular Materials, 1996, 5:19
[32] 乐红胜．粉末注射成形充模流动及冷却凝固过程计算机模拟．硕士学位论文，长沙：中南工业大学，1997
[33] 毛金英．粉末注射成形二维充模流动计算机模拟．硕士学位论文，长沙：中南工业大学，1999
[34] 林好转．金属粉末注射成形的喂料性能及成形的模具研究．博士后研究工作报告，长沙：中南工业大学，1998
[35] 曲选辉，温宏宇，敖晖，郑洲顺．粉末注射成形过程计算机模拟研究．材料工程，2001，6：33～36
[36] 曲选辉，温宏宇．粉末注射成形技术及其应用．2000年材料科学与工程新进展(上)，北京：冶金工业出版社，2001：18-22
[37] 李德群．注塑模CAD／CAE／CAM发展综述．模具工业，1996，7(1)：4
[38] 张佑生．塑料模具计算机辅助设计．机械工业出版社，1999
[39] 陈静波，刘春太，王丽霞，申长雨．注射模Z-MOLD软件的开发与应用．模具工业，1997，11：9-12
[40] C. J. Hwang. Computer-Aided Engineering System for Powder Injection Molding Filling Process. PIM 2000 World Congress
[41] 毛金英，曲选辉，乐红胜，林好转，李益民．粉末注射成形充模过程中凝固层形成规律的计算与分析．粉末冶金技术，1999，17(1)：14
[42] B. H. Rosof The Metal Injection Molding Process Comes of Age. J. of Mater., 1989, 41(8): 13～16
[43] 汪宏俊．流体力学，北京：高等教育出版社，1988
[44] R．M．German著，曲选辉等译．粉末注射成形，中南大学出版社，2001
[45] O.A. Novac, D. Anton and T. Novac. The Rheological Behavior of Some Binders and Plastics Used in Injection Molding. Powder Metallurgy 94, 1994: 113
[46] Florin Ilinca. Metal Injection Molding: Simulation of Three-Dimensional Flow with Free Surface Boundary and Experimental Comparison. ANTEC 2000: 718
[47] V.V. Bilovol, L. Kowalski and J. Duszxzyk. Modeling of Transient TemperatureFields during Filling Stage of Powder Injection Molding. Powder Metallurgy, 2000, 43(3): 228～232
[48] 王成，邵敏．有限单元法基本原理和数值方法．第二版，清华大学出版社，1997
[49] 章本照．流体力学中的有限元法．机械工业出版社，1986
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