國內(nèi)外冷熱沖壓技術(shù)回顧于綜述

1、A review on hot stampingThe production of high strength steel components with desired properties by hot stamping (also called press hardening) requires a profound knowledge and control of the forming procedures. In this way, the final part properties become predictable and adjustable on the basis of

2、 the different process parameters and their interaction. In addition to parameters of conventional cold forming, thermal and microstructural parameters complicate the description of mechanical phenomena during hot stamping, which are essential for the explanation of all physical phenomena of this fo

3、rming method. In this article, the state of the art in the thermal, mechanical, microstructural, and technological fields of hot stamping are reviewed. The investigations of all process sequences, from heating of the blank to hot stamping and subsequent further processes, are described. The survey o

4、f existing works has revealed several gaps in the fields of forming-dependent phase transformation, continuous flow behavior during the whole process, correlation between mechanical and geometrical part properties, and industrial application of some advanced processes. The review aims at providing a

5、n insight into the forming procedure backgrounds and shows the great potential for further investigations and innovation in the field of hot sheet metal forming.Development of tribo-simulator for hot stamping沖壓工藝過程仿真開發(fā)Coefficients of friction were measured at elevated temperatures using a hot flat s

6、trip drawing test machine newly developed by the authors for the purpose of confirming the coefficients of friction used for the FEM simulation of hot stamping. To examine the functions of the tribo-simulator, the coefficients of friction are measured using hot rolling oil with an emulsion, which is

7、 supplied continuously, while varying the drawing speed, drawing pressure and temperature. From the experimental results, it was shown that the coefficient of friction in hot stamping can be measured using this tribo-simulator. The measured coefficients of friction can be used as values in the FEM s

8、imulation of hot stamping. Moreover, the tribological behavior at the interface between the die and strip in hot stamping can be evaluated from the coefficient of friction, because it is one of the quantitative values used to represent the tribological behavior between the die and blank.Die design f

9、or stamping a notebook case with magnesium alloy sheetsIn the present study, the stamping process for manufacturing a notebook top cover case with LZ91 magnesiumlithium alloy sheet at room temperature was examined using both the experimental approach and the finite element analysis. A four-operation

10、 stamping process was developed to eliminate both the fracture and wrinkle defects occurred in the stamping process of the top cover case. In order to validate the finite element analysis, an actual four-operation stamping process was conducted with the use of 0.6mm thick LZ91 sheet as the blank. A

11、good agreement in the thickness distribution at various locations between the experimental data and the finite element results confirmed the accuracy and efficiency of the finite element analysis. The superior formability of LZ91 sheet at room temperature was also demonstrated in the present study b

12、y successful manufacturing of the notebook top cover case. The proposed four-operation process lends itself to an efficient approach to form the hinge in the notebook with less number of operational procedures than that required in the current practice. It also confirms that the notebook cover cases

13、 can be produced with LZ91 magnesium alloy sheet by the stamping process. It provides an alternative to the electronics industry in the application of magnesium alloys.Improving the accuracy of contact-type drawbead elements in panel stamping analysis面板沖壓的材料與接觸類型A finite element modeling technique i

14、s proposed to improve the accuracy of contact-type drawbead elements in panel forming analyses, and a performance assessment in terms of part border and thickness predictions is presented in conjunction with panel stamping experiments of two automotive sheets. Inherent model limitations causing inco

15、rrect part geometry and thickness predictions are, firstly, evaluated considering blank deformations on a plainstrain section of a stamping die. The influence of omitted drawbead geometry and overestimated drawbead exit thickness are described analytically, and a closed form expression is obtained t

16、o correct draw-in model error. Then a sectional deformation model is used to calculate restraint force and drawbead exit thickness for a particular blank and drawbead design. The proposed technique is applied in process modeling of polygon shaped panels made of draw-quality and bake-hardenable steel

17、s. Three bead penetrations were investigated in process simulations as well as in stamping experiments. The same blankholder force was applied in all process conditions. Computed draw-in and thickness distributions were compared with on-part measurements using an experimental panel-draw die. It was

18、determined that drawbead models based on force parameters only resulted in remarkably high thickness values at the die entry and mostly overestimated draw-in along panel border lines. An evaluation of thickness distributions computed with proposed technique showed an improved correlation with experi

19、ment results of both blank materials and confirmed the use of the drawbead exit thickness as a drawbead modeling parameter. Effects of bead penetration on panel border lines were also simulated in accord with stamping experiments.熱沖壓機(jī)床與設(shè)備及其冷卻系統(tǒng)設(shè)計(jì)Design of Hot Stamping Tools with Cooling SystemHot st

20、amping with high strength steel is becoming more popular in automotive industry. In hot stamping, blanks are hot formed and press hardened in a water-cooled tool to achieve high strength. Hence, design of the tool with necessary cooling significantly influences the final properties of the blank and

21、the process time. In this paper a new method based on systematic optimization to design cooling ducts in tool is introduced. The optimization procedure was coupled with FE analysis and a specific evolutionary algorithm. Through this procedure each tool component was separately optimized. Subsequentl

22、y, the hot stamping process was simulated both thermally and thermo-mechanically with the combination of optimized solutions.熱沖壓的材料機(jī)械性能Investigation of the thermo-mechanical properties of hot stamping steelsWithin the innovative hot forming process for sheet metals, called hot stamping, it is possib

23、le to combine forming and quenching in one process step. This affords the opportunity to manufacture components with complex geometric shapes, high strength and a minimum of springback which currently find applications as crash relevant components in the automotive industry. As standard material for

24、 hot stamping the quenchenable high strength steel 22MnB5 is commonly used. With regard to the numerical modeling of the process, the knowledge of thermal and thermo-mechanical properties of the material is required. To determine the thermo-mechanical material characteristics, the flow behavior of t

25、he steel 22MnB5 in the austenitic state has been investigated by conductive, hot tensile tests with a Gleeble 1500 system dependent on the timetemperature characteristic of the hot stamping process.金屬鈑金快速?zèng)_壓先進(jìn)系統(tǒng)Fast FE analysis system for sheet metal stampingFASTAMPFASTAMP is a fast FE analysis syste

26、m for sheet metal stamping, which is based on an improved inverse approach and dynamic explicit method. The improved algorithm successfully avoids the strain localization problem existing in plastic deformation theory to lay foundation for the inverse approach. Quadrilateral membrane elements togeth

27、er with DKQ bend element are used in the algorithm to considering bending effect. More accurate model is built in the system so that the process parameters, such as blank-holding force, friction and drawbead restriction, can be taken into account. Press types, eject plate and other influence factors

28、 on sheet metal forming are also considered. As a result, the system can be applied to potential defects detection, formability analysis, material selection and process verification. Product design, process planning and die design can be integrated by FASTAMP, so that product formability can be ensu

29、red, optimization of stamping process and die structure achieved.鈑金沖壓的電子電磁輔助自控設(shè)施Electromagnetically assisted sheet metal stampingA new approach, electromagnetically assisted sheet metal stamping, has been developed to alter strain distribution and improve formability in sheet metal stamping. In this

30、 study, this new approach was applied to form a non-symmetric panel from Al 6111-T4. The results show that this new approach greatly increased the draw depth of the formed panel, compared with conventional stamping. A detailed analysis of strain distribution, stretching and draw-in shows that both a

31、 more homogeneous strain distribution and enhanced draw-in contribute to producing deeper pans in a single press operation. This work demonstrates the feasibility of electromagnetically assisted sheet metal stamping, which offers a much improved ability to make complex components in a single press s

32、troke as compared to conventional stamping.多步鈑金沖壓中的材料厚度變化率保證 使用的優(yōu)化軟件Minimization of the thickness variation in multi-step sheet metal stampingThis paper presents an efficient method to optimize the intermedial tool surfaces in the multi-step sheet metal stamping process to obtain improved quality of

33、 a product at the end of forming. The proposed method is based on a combination of finite element modeling (FEM) and the response surface method (RSM). The objective of the optimization is to minimize the thickness variation of the part at the final stage. The constraint function of local fracture i

34、s introduced by the use of the forming limit curve (FLC). With acceptable accuracy and high efficiency, the multi-step inverse method is used together with RSM to check various intermediate surfaces to search for the optimal shape parameters. After the convergence of the optimization, the result is

35、validated using commercial software DYNAFORM.Application of a feasible formability diagram for the effective design in stamping processes of automotive panels圖表化沖壓過程柔性化設(shè)計(jì)方法的應(yīng)用 自動(dòng)面板控制The objective of this study is to propose a method of process design that uses a feasible formability diagram, which d

36、enotes the safe region without fracture and wrinkle, for the effective and rapid design of stamping processes. To determine the feasible formability diagram, FE-analyses have been performed for combinations of process variables that correspond to the orthogonal array of design of experiments. Subseq

37、uently, the characteristic values for fracture and wrinkle have been estimated from the results of FE-analyses on the basis of the forming limit diagram. The characteristic values for all combinations within a whole range of process variables have been predicted through the training of an artificial

38、 neural network. The feasible formability diagram has been finally determined for all combinations of process variables. The stamping processes of automotive panels to support suspension module, such as the turret suspension and the wheel house, have been taken as examples to verify the effectivenes

39、s of process design through feasible formability diagram. A comparison of the FE-simulation results with the experimental results reveals that the design of stamping processes through feasible formability diagram is efficient and suitable for actual processes.Development of nano-columnar carbon coat

40、ing for dry micro-stampingTwo-stage cold stamping of magnesium alloy cups having small corner radius杯型零件的兩步化沖壓方法A two-stage cold stamping process for forming magnesium alloy cups having a small corner radius from commercial magnesium alloy sheets was developed. In the 1st stage, a cup having large c

41、orner radius was formed by deep drawing using a punch having large corner radius, and the corner radius of the cup was decreased by compressing the side wall in the 2nd stage. In the deep drawing of the 1st stage, fracture was prevented by decreasing the concentration of deformation with the punch h

42、aving large corner radius. The magnesium alloy sheets were annealed at 500C to increase the cold formability. Circular and square cups having small corner radii were formed by the two-stage cold stamping. For the circular cup, the height of the cup was increased by ironing the side wall in the 1st s

43、tage. The radii of the bottom and side corners of the square cup were reduced by a rubber punch for applying pressure at these corners in the 2nd stage. It was found that comparatively shallow magnesium alloy square cups used as cases of laptop computers and mobile phones can be satisfactorily forme

44、d at room temperature without heating by the two-stage stamping.Numerical simulation of hot stamping of quenchable boron steelQuenchable boron steel is a new type of ultra-high-strength steel used for automotive parts to reduce the weight of automobiles and maintain the safety requirements. On the b

45、asis of experimental data of mechanics and thermal physical properties, a material model under hot stamping condition of quenchable steel was set up, and the numerical simulation to the whole hot stamping process of hot forming, quenching and spring-back of bending parts was made with ABAQUS softwar

46、e. The results show that the springback of hot stamping parts increases when the blank-holder force (BHF) decreases; and it increases when the clearance between punch and dies increases and when the die radius increases. The simulation results are basically in agreement with experimental results.熱沖壓工藝過程的數(shù)字化仿真A numerical investigation to the strategies of the localised heating for micro-part stampingLocal heating renders attractive characteristics for achieving high efficiency of metal forming. With reference to micro-par