In order to meet the demand of prehardened steel for large section plastic mould and save energy, a nonquenched prehardened （NQP） steel is developed. The temperature field of a large block is researched by finite el...In order to meet the demand of prehardened steel for large section plastic mould and save energy, a nonquenched prehardened （NQP） steel is developed. The temperature field of a large block is researched by finite element method simulation and 9 test steels are designed in the laboratory. Their microstructures and hardness are investigated when they are air cooled and control cooled at cooling rate similar to the simulation. The result shows that the hardness uniformity through section is closely correlated to bainitic hardenability for the NQP steel, and the hardness of one test steel （0.27C-1.95Mn-1.04Cr-0.45Mo-0.1V） fluctuates between HRC 40 and 43 under both cooling conditions. The test steel has better machinability compared with C45 steel, and the NQP steel is produced successfully in the factory based on the laboratory results. Its microstructure is bainite, and it is distributed uniformly through the size of 460 mm×800 mm×3 200 mm.展开更多
A new design of copper-bearing non-quenched plastic mold steel is presented and explained. Two kinds of microstrueture can be obtained from this new type copper-bearing steel via cooling with different cooling rates, ...A new design of copper-bearing non-quenched plastic mold steel is presented and explained. Two kinds of microstrueture can be obtained from this new type copper-bearing steel via cooling with different cooling rates, bain- ite and a mixed microstructure consisting of ferrite and bainite. It is found that, after proper tempering process, the hardness will be increased. Moreover, the hardness difference between different microstructures will be reduced. For further investigation, the samples tempered at different temperatures were examined by XRD and 3PAP （three di- mensional atom probe） analysis. Results show that the improvement is contributed mainly by the precipitation of Cu phase and transformation of residual austenite.展开更多
The influence of austenitizing temperature on the microstructure and corrosion resistance of 55Cr18MolVN high-nitrogen plastic mould steel was investigated. The microstructure, elemental distribution and Cr-depleted z...The influence of austenitizing temperature on the microstructure and corrosion resistance of 55Cr18MolVN high-nitrogen plastic mould steel was investigated. The microstructure, elemental distribution and Cr-depleted zone of different heat-treated samples were investigated by X-ray diffraction, electron probe microanalyzer analysis, and trans- mission electron microscopy. The corrosion resistance was evaluated using electrochemical measurements, and the analysis of passive film was carded out by X-ray photoelectron spectroscopy. The results indicated that the volume fraction of precipitates decreased, and the homogeneity of elements was improved with increasing austenitizing temperature. The degree of Cr-depleted zone around coarse M23C6 was severer than that around M2N, and pitting corrosion initiated preferentially around M23C6. The corrosion resistance of the samples increased with the austenitizing temperature. With the increase in austenitizing temperature, the passive film was thickened and Cr（III）cr2O3 in the inner layer of passive film was enriched, which enhanced the corrosion resistance of the steel. The higher content of nitrogen in solid solution at higher austenitizing temperature contributed to the increased intensity of CrN and NH3, leading to the increase in pH value in the pit, and promoting the repassivation of 55Cr18Mo1N steel.展开更多
A CAD approach which can optimize and automate the parting direction determination is presented. The approach is based on the geometrical and topological information of the solid modelling of the plastic moulded part ...A CAD approach which can optimize and automate the parting direction determination is presented. The approach is based on the geometrical and topological information of the solid modelling of the plastic moulded part in order to select a pair of optimal parting directions of a two plate mould which minimizes the number of side cores. The shell of a part is divided into inter influential regions and non influential faces in the mould design point of view. Through analyzing and computing the accessibility direction cones of the inter influential regions, the optimal parting directions can be determined automatically.展开更多
The gas in plastics mould has great influence on performance, appearance and lifespan of the injection molded parts. Venting channel and its appendix system should be used for gas exhausting in general. However, the d...The gas in plastics mould has great influence on performance, appearance and lifespan of the injection molded parts. Venting channel and its appendix system should be used for gas exhausting in general. However, the dependence on the venting system complicates the mould design. Furthermore in certain condition, it is difficult to integrate the venting system into the mould. Currently a kind of mold material which has gas permeability has been developed in abroad, but the applications of this mold material were restricted by its higher cost and smaller size. In this research, a porous material which was made by powder metallurgy was applied to plastic mould to replace the venting system. Permeability of the steel with different secondary processing was tested and compared with a special apparatus. The metallographic samples of the steel with different secondary processing were prepared and investigated. Finally an actual injection set was established to investigate the applications of permeable steel. The metallographies indicate that the micro-holes inside permeable steel were interconnected. Moulds made of permeable steel exhibit good permeability in the plastic-injection experiments and gas generated in the mould cavity was smoothly exhausted. The melted plastic did not penetrate into the mould or block in the micro-holes. After several times of plastic-injection experiments, the mould still retained good permeability. The strength of this permeable steel is between 200–250 MPa and suitable for industrial applications. The venting systems simplified by permeable steel in plastic-injection have simple structures, which can be applied into any place that requires gas exhausting.展开更多
The improvement of machining behavior of prehardened-mould steel for plastic is realized by using computer-aided composition design in this work. The results showed that the matrix composition of large sectional preha...The improvement of machining behavior of prehardened-mould steel for plastic is realized by using computer-aided composition design in this work. The results showed that the matrix composition of large sectional prehardened mould steel for plastic markedly influences the precipitation of non-metallic inclusion and the control of composition aided by Thermo-Calc software package minimizes the amount of detrimental oxide inclusion. In addition the modification of calcium is optimized in the light of composition design.展开更多
Today, the time-to-market for plastic products ar e getting shorter, thus the lead-time for making the injection mould is decreasin g. There is potential in timesavings in the mould design stage because the design pro...Today, the time-to-market for plastic products ar e getting shorter, thus the lead-time for making the injection mould is decreasin g. There is potential in timesavings in the mould design stage because the design process that is repeatable for every mould design can be standardized. T he preliminary work of any final plastic injection mould design is to always pro vide an initial design of the mould assembly for product designers (customers) p rior to receiving the final product CAD data. Traditionally and even up till no w, this initial design is always created using 2D CAD packages. The information used for the initial design is based on the technical discussion checklist, in which most mould makers have their own standards. This checklist is also being used as a quotation since the most basic information of the mould in the particu lar project is being recorded in it. The basic information in this checklist in cludes the number of cavities, the type of mould base to be used, the moulding m achine to be used for the moulding, the type of gating system, the type of resin material used and its shrinkage value etc. Information on special requirements such as the number of sliders or lifters to be used is also listed in the check list. At this stage, there is still no information on the cooling and ejection design since they are greatly dependent on the final product CAD data. This res earch focuses on the methodology of providing the initial design in 3D solid bas ed on the technical discussion checklist, which takes the role of the overall st andard template since every sub-design has its own standard template. An examp le of a sub-design that has its own standard template is the cavity layout desi gn. The cavity layout for plastic injection moulds can be designed by controlli ng the geometrical parameters using a standardization template. The standardiza tion template for the cavity layout design consists of configurations for the po ssible layouts. Each configuration of the layout design has its own layout desi gn table of all the geometrical parameters. This standardization template is pr e-defined in the layout design level of the mould assembly design. This ensure s that the required configuration can be loaded into the mould assembly design v ery quickly without having the need to redesign the layout. This makes it usefu l for technical discussions between the product designers and mould designers pr ior to the manufacture of the mould. Changes can be made to the 3D cavity layou t design immediately during the discussions thus the savings in time and avo idance of miscommunications.展开更多
A new technology of functionally graded materials(FGM) mould fabricated by plasma spraying and arc spraying was developed. According to applied characteristic of plastic mould, the reasonable coatings of FGM were desi...A new technology of functionally graded materials(FGM) mould fabricated by plasma spraying and arc spraying was developed. According to applied characteristic of plastic mould, the reasonable coatings of FGM were designed and their microstructures were analyzed. At the same time, some key problems were solved including spray mould fabricating, FGM forming and demoulding, etc. The results show that the service performance of the FGM mould is much more excellent than the one composed of the traditional materials, and the life span can also be greatly increased. The technology will have a significant influence on materials development in mould industry.展开更多
基金Item Sponsored by Shanghai Leading Academic Discipline Project (T0101)
文摘In order to meet the demand of prehardened steel for large section plastic mould and save energy, a nonquenched prehardened （NQP） steel is developed. The temperature field of a large block is researched by finite element method simulation and 9 test steels are designed in the laboratory. Their microstructures and hardness are investigated when they are air cooled and control cooled at cooling rate similar to the simulation. The result shows that the hardness uniformity through section is closely correlated to bainitic hardenability for the NQP steel, and the hardness of one test steel （0.27C-1.95Mn-1.04Cr-0.45Mo-0.1V） fluctuates between HRC 40 and 43 under both cooling conditions. The test steel has better machinability compared with C45 steel, and the NQP steel is produced successfully in the factory based on the laboratory results. Its microstructure is bainite, and it is distributed uniformly through the size of 460 mm×800 mm×3 200 mm.
基金Sponsored by National Key Technology Research and Development Program in 11th Five-Year Plan of China(2007BAE51B04)
文摘A new design of copper-bearing non-quenched plastic mold steel is presented and explained. Two kinds of microstrueture can be obtained from this new type copper-bearing steel via cooling with different cooling rates, bain- ite and a mixed microstructure consisting of ferrite and bainite. It is found that, after proper tempering process, the hardness will be increased. Moreover, the hardness difference between different microstructures will be reduced. For further investigation, the samples tempered at different temperatures were examined by XRD and 3PAP （three di- mensional atom probe） analysis. Results show that the improvement is contributed mainly by the precipitation of Cu phase and transformation of residual austenite.
基金financially supported by National Natural Science Foundation of China (Grant Nos.51304041, 51434004 and U1435205)Fundamental Research Funds for the Central Universities (Grant No. N150204007)
文摘The influence of austenitizing temperature on the microstructure and corrosion resistance of 55Cr18MolVN high-nitrogen plastic mould steel was investigated. The microstructure, elemental distribution and Cr-depleted zone of different heat-treated samples were investigated by X-ray diffraction, electron probe microanalyzer analysis, and trans- mission electron microscopy. The corrosion resistance was evaluated using electrochemical measurements, and the analysis of passive film was carded out by X-ray photoelectron spectroscopy. The results indicated that the volume fraction of precipitates decreased, and the homogeneity of elements was improved with increasing austenitizing temperature. The degree of Cr-depleted zone around coarse M23C6 was severer than that around M2N, and pitting corrosion initiated preferentially around M23C6. The corrosion resistance of the samples increased with the austenitizing temperature. With the increase in austenitizing temperature, the passive film was thickened and Cr（III）cr2O3 in the inner layer of passive film was enriched, which enhanced the corrosion resistance of the steel. The higher content of nitrogen in solid solution at higher austenitizing temperature contributed to the increased intensity of CrN and NH3, leading to the increase in pH value in the pit, and promoting the repassivation of 55Cr18Mo1N steel.
文摘A CAD approach which can optimize and automate the parting direction determination is presented. The approach is based on the geometrical and topological information of the solid modelling of the plastic moulded part in order to select a pair of optimal parting directions of a two plate mould which minimizes the number of side cores. The shell of a part is divided into inter influential regions and non influential faces in the mould design point of view. Through analyzing and computing the accessibility direction cones of the inter influential regions, the optimal parting directions can be determined automatically.
基金supported by Guangdong-Hong Kong Key Project of China (Grant No. 2007Z010)National Basic Research Program of China (973 Program, Grant No. 2007CB616905)
文摘The gas in plastics mould has great influence on performance, appearance and lifespan of the injection molded parts. Venting channel and its appendix system should be used for gas exhausting in general. However, the dependence on the venting system complicates the mould design. Furthermore in certain condition, it is difficult to integrate the venting system into the mould. Currently a kind of mold material which has gas permeability has been developed in abroad, but the applications of this mold material were restricted by its higher cost and smaller size. In this research, a porous material which was made by powder metallurgy was applied to plastic mould to replace the venting system. Permeability of the steel with different secondary processing was tested and compared with a special apparatus. The metallographic samples of the steel with different secondary processing were prepared and investigated. Finally an actual injection set was established to investigate the applications of permeable steel. The metallographies indicate that the micro-holes inside permeable steel were interconnected. Moulds made of permeable steel exhibit good permeability in the plastic-injection experiments and gas generated in the mould cavity was smoothly exhausted. The melted plastic did not penetrate into the mould or block in the micro-holes. After several times of plastic-injection experiments, the mould still retained good permeability. The strength of this permeable steel is between 200–250 MPa and suitable for industrial applications. The venting systems simplified by permeable steel in plastic-injection have simple structures, which can be applied into any place that requires gas exhausting.
文摘The improvement of machining behavior of prehardened-mould steel for plastic is realized by using computer-aided composition design in this work. The results showed that the matrix composition of large sectional prehardened mould steel for plastic markedly influences the precipitation of non-metallic inclusion and the control of composition aided by Thermo-Calc software package minimizes the amount of detrimental oxide inclusion. In addition the modification of calcium is optimized in the light of composition design.
文摘Today, the time-to-market for plastic products ar e getting shorter, thus the lead-time for making the injection mould is decreasin g. There is potential in timesavings in the mould design stage because the design process that is repeatable for every mould design can be standardized. T he preliminary work of any final plastic injection mould design is to always pro vide an initial design of the mould assembly for product designers (customers) p rior to receiving the final product CAD data. Traditionally and even up till no w, this initial design is always created using 2D CAD packages. The information used for the initial design is based on the technical discussion checklist, in which most mould makers have their own standards. This checklist is also being used as a quotation since the most basic information of the mould in the particu lar project is being recorded in it. The basic information in this checklist in cludes the number of cavities, the type of mould base to be used, the moulding m achine to be used for the moulding, the type of gating system, the type of resin material used and its shrinkage value etc. Information on special requirements such as the number of sliders or lifters to be used is also listed in the check list. At this stage, there is still no information on the cooling and ejection design since they are greatly dependent on the final product CAD data. This res earch focuses on the methodology of providing the initial design in 3D solid bas ed on the technical discussion checklist, which takes the role of the overall st andard template since every sub-design has its own standard template. An examp le of a sub-design that has its own standard template is the cavity layout desi gn. The cavity layout for plastic injection moulds can be designed by controlli ng the geometrical parameters using a standardization template. The standardiza tion template for the cavity layout design consists of configurations for the po ssible layouts. Each configuration of the layout design has its own layout desi gn table of all the geometrical parameters. This standardization template is pr e-defined in the layout design level of the mould assembly design. This ensure s that the required configuration can be loaded into the mould assembly design v ery quickly without having the need to redesign the layout. This makes it usefu l for technical discussions between the product designers and mould designers pr ior to the manufacture of the mould. Changes can be made to the 3D cavity layou t design immediately during the discussions thus the savings in time and avo idance of miscommunications.
基金Projects(50175035 50375024) supported by the National Natural Science Foundation of China+1 种基金 Project(E0210024) sup ported by the Natural Science Foundation of Fujian Province of China Project(2002H044) supported by the Program of High Science andTec
文摘A new technology of functionally graded materials(FGM) mould fabricated by plasma spraying and arc spraying was developed. According to applied characteristic of plastic mould, the reasonable coatings of FGM were designed and their microstructures were analyzed. At the same time, some key problems were solved including spray mould fabricating, FGM forming and demoulding, etc. The results show that the service performance of the FGM mould is much more excellent than the one composed of the traditional materials, and the life span can also be greatly increased. The technology will have a significant influence on materials development in mould industry.
