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《钢铁研究学报(英文版)》2016,(3):185-189
The process of automobile lightweight can be promoted by the application of tailor rolled blank(TRB)in the automobile industry.Therefore,research on the formability of TRB is of good practical significance and application value because of the enormous potential of TRB in the aspect of automobile lightweight.Aiming at the present condition of lack of researches on the influence of characteristic parameters on TRB drawing process,the drawing formability of TRB was studied with a combination method of simulation and experiment by taking square box as the research object.Firstly,drawing simulation and experiment of TRB were carried out.Then,effects of thickness transition zone(TTZ)position and blank size on the drawing formability of TRB were analyzed.Forming limit and TTZ movement for TRB square box during the drawing process were respectively discussed,when transition zones of TRB were located at different positions and blanks were of different sizes.The results indicate that lubrication condition exerts greater influence on TRB forming limit in comparison with TTZ movement,and the smaller blank size and TTZ being located at the blank center or slightly offset to the thinner side are preferable for acquiring greater forming limit and smaller TTZ movement. 相似文献
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为了推动轧制差厚板在汽车梁结构件上的应用,以U型件为对象,研究了轧制差厚板的纵向弯曲回弹特性。首先完成了差厚板U型零件纵向弯曲成形数值模拟,分析了差厚板的回弹趋势,讨论了差厚板的应力分布,揭示了差厚板弯曲回弹规律,探讨了差厚板等效应力的影响因素,并通过试验对回弹仿真结果进行验证。结果表明,不均匀的应力分布是纵向弯曲的差厚板U型件沿弯曲轴方向上回弹不一致的根本原因,退火处理能够减小差厚板卸载前后的应力差,从而实现抑制差厚板回弹的作用。差厚板的板料尺寸、厚度、过渡区长度均会对差厚板的等效应力造成较大影响,从而改变差厚板的回弹大小及分布。另外,差厚板零件不同厚度部位的回弹相互牵制,使得各部分的回弹量趋向一致,从而导致差厚板的回弹量均介于薄、厚等厚板之间。 相似文献
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LEIJunxiang 《钢铁研究学报(英文版)》2004,11(5):44-49
Based on the deformation characteristic of regular polygonal box stamped parts and the superfluous triangle material wrinkle model, the criterion of regular polygonal box stamped parts without wrinkle was deduced and used to predict and control the wrinkle limit. According to the fracture model, the criterion of regular polygonal box stamped parts without fracture was deduced and used to predict and control the fracture limit. Combining the criterion for stamping without wrinkle with that without fracture, the stamping criterion of regular polygonal box stamped parts was obtained to predict and control the stamping limit. Taken the stainless steel 0Cr18Ni9 (SUS304) sheet and the square box stamped part as examples, the limit diagram was given to predict and control the wrinkle, fracture and stamping limits. It is suitable for the deep drawing without flange, the deep drawing and stretching combined forming with flange and the rigid punch stretching of plane blank. The limit deep-drawing coefficient and the minimum deep-drawing coefficient can be determined, and the appropriate BHF (blank holder force) and the deep-drawing force can be chosen. These provide a reference for the technology planning, the die and mold design and the equipment determination, and a new criterion evaluating sheet stamping formability, which predicts and controls the stamping process, can be applied to the deep drawing under constant or variable BHF conditions. 相似文献
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《钢铁研究学报(英文版)》2016,(12):1249-1254
Research on the formability of tailor rolled blank (TRB)is of good practical significance and application value because of the enormous potential of TRB in the aspect of automobile lightweight.However,the forming of TRB is problematic because of the varying properties;especially,springback is a main challenge.The transverse bending (bending axis is perpendicular to the rolling direction)of TRB U-channel was studied through simulation and experiment.The forming characteristics of TRB U-channel during transverse bending were analyzed.The mecha-nisms of forming defects,including bending springback and thickness transition zone (TTZ)movement,were re-vealed.On this basis,effects of blank geometric parameters on springback and TTZ movement were discussed.The results indicate that springback and TTZ movement happen during transverse bending of TRB U-channel.Nonuni-form stress distribution is the most fundamental reason for the occurrence of springback of TRB during transverse bending.Annealing can eliminate nonuniform stress distribution,and thus diminish springback of TRB,especially springback on the thinner side.Therefore,springback of the whole TRB becomes more uniform.However,annealing can increase the TTZ movement.Blank thickness and TTZ position are the main factors affecting the formability of TRB U-channel during transverse bending. 相似文献
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In order to grasp the springback rule of TRB (tailor rolled blank) parts after forming, the springback behavior of TRB was investigated by integrating such three means as theoretical research, numerical simulation and stamping experiments. Fundamental theories of springback were analyzed. The stamping and springback processes of annealed 1.2/2.0 mm TRB, 1.2 mm and 2.0 mm plates for U-channel were simulated, and the simulation results were compared with the experiments. The results indicate that the springback of TRB falls in between those of the 1.2 mm and 2.0 mm plates. It is desirable for the TRB U-channel to have die clearance of 1.1 times maximum blank thickness and friction coefficient of about 0.12, and longer thickness transition zone is preferable. The simulation data demonstrate reasonably good agreement with the experiments. 相似文献
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《钢铁研究学报(英文版)》2015,(8)
The vertical motion control of the roll was studied in order to improve the accuracy in simulation of variable gauge rolling. The discretization was carried out in the transition zone of TRB according to the principle of volume invariance. Based on this assumption, the formula for time step of vertical motion of rolls was proposed and the time-displacement curve of the vertical motion of rolls was established. In the preliminary simulation, the time-displacement curve was used as an initial method to control the vertical motion of rolls. Based on the simulation result, the formula for vertical velocity of roll in variable gauge rolling was derived from the common rolling principle. According to the formula, reasonable vertical velocity of rolls in the subsequent simulation was determined. It can accurately control the motion of rolls along the vertical direction. The desired thickness and outline profile of transition zone were acquired and the formula proved effective by the simulation. Further analysis shows that the di fference of thickness in the thick zone and the thin zone of TRB, length of the transition zone of TRB, radius of work rolls and rotation speed of rolls have a significant effect on the vertical velocity of rolls. 相似文献
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薄腹板异形坯更体现了近终形的特点。采用有限元数值模拟计算了薄腹板异形坯连铸温度场,分析了不同拉速、比水量对连铸过程温度、坯壳厚度和液芯长度的影响。结果表明:异形坯不同位置的温度和坯壳厚度不均匀,当异形坯腹板较薄时,腹板处凝固传热较慢,腹板处和R角处坯壳最薄弱,比翼缘边部薄约4mm;拉速每提高0.1m/s,异形坯出结晶器时的表面温度会提高约80~100℃,坯壳厚度会减薄0.8~1.2mm,液芯长度增加1.2~1.6m;比水量每提高0.05L/kg,异形坯出二冷段时的表面温度会降低约8~16℃,液芯长度缩小0.13m。 相似文献
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In this paper the air bending of Tailor Rolled Blanks (TRB) to load optimised profiles is investigated. A new flexible modular tool system has been developed in order to locally adapt the die height to the spring back which is more pronounced in thinner areas in comparison to thicker areas of the TRB. With the new tool system the dies can be modulated according to the thickness distribution of the Tailor Rolled Blank, whereas the amount of die lifting depends on the thickness difference and the corresponding variance of mechanical properties. In bending tests with several specimens having a constant thickness a linear relation between the increasing part angle and a stepwise increased die lifting was observed. With this linear dependency the amount of die lifting can be calculated and thus applied on bending of TRB. Special consideration is required for the die adjustment in the area of the linear thickness transition, therefore three different die arrangements have been investigated. The results of different bending tests are compared and evaluated in order to apply the new technique to form a new car body floor structure in profile intensive construction. By using load optimised profiles in combination with a steel 22MnB5 which has been heat‐treated at defined sections the survival space of a car passenger in a side pole impact has been enormously increased by more than 40 %. 相似文献
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The springback of tailor rolled blanks with quenching and partitioning steels was investigated.In order to find out the springback behavior and related influence factors for the novel sheets,both experimental and simulation methods have been used to compare and analyze the springback characteristics of equal thickness blanks and tailor rolled blanks in U-channel forming.From the results,the overall springback angles of tailor rolled blanks at thin and thick sides are respectively 106.79° and 99.705°,which are both lower than those of the corresponding equal thickness blanks.Due to the existence of the thickness transition zone,the stress distribution in thin and thick sides of blanks is changed.The location of dangerous region in thin side of tailor rolled blanks is closer to the end of side,and the thick side moved to the middle of straight wall,which are different with the equal thickness blanks.Afterwards,the released quantitles of tangential stress and strain per unit section of blank are adopted to calculate relative springback angles and give novel evaluation criteria for qualitatively analyzing the amount of springback angles.By comparing the results,it shows that the tangential strain method is more suitable for the actual situation. 相似文献
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In the present work, tensile behavior of tailor rolled blanks (TRBs) made of DP590 was studied. The TRBs were produced by variable gauge rolling. The tensile specimens of TRB had thickness ratios (Tr) of 0.47, 0.52, 0.68, 0.78 and 0.89, whereas the lengths of thickness transition zone (TTZ) were 58, 75 and 110 mm. The results of tensile test along with SEM and EBSD observations revealed that the total elongation of TRBs is strongly dependent on the TTZ geometry. Accordingly, it was found out that the total elongation increases with increasing Tr. However, unprecedented results were obtained for variations of total percent elongation versus the length of TTZ. In case of tensile specimens with identical gauge length, the total elongation decreases with increasing the length of TTZ. To justify the results, a novel geometrical parameter called effective length ratio (ELR) was introduced. This new parameter showed a meaningful relation with the total elongation. Accordingly, the effects of TTZ position and geometry on the total elongation were studied utilizing ELR parameter. It was concluded that the total elongation increases with increasing the ELR parameter. Furthermore, a linear correlation between ELR and total elongation was established. This can be used to interpolate the tensile behavior of TRBs for any intermediate conditions which can be more applicable for prediction of tensile behavior without performing any tests. Finally, the influence of thickness ratio on the probability of fracture from a certain region was discussed. 相似文献
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This paper describes an experimental investigation into the time-dependent deformation of pultruded glass fiber reinforced polymer (GFRP) composite columns under an axial-compressive loading at the environmental controlling room with a constant temperature and relative humidity. Tests were conducted on two types of cross-sectional columns: closed-cross section such as square tube (box) and opened-cross section such as wide flange. Both types of columns were 1,200 mm in length, and had cross-sectional dimensions of 102 mm×102 mm and with a 6.4 mm thickness. A total of eight GFRP composite columns were tested at four different stress levels; 20, 30, 40, and 50% of the average ultimate compressive strength from the short-term column tests. The experiments were conducted for approximately 2,500 h with an individual hydraulic loading jack system. The test results indicate that Findley’s power law model can be successfully used to predict time-dependent deformation of GFRP composite columns, and the time-dependent compressive elastic modulus would be decreased as much as 30% of initial value over a 50-year period. 相似文献
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The expression of the solute distribution in columnar crystal zone was deduced when the solid-liquid interface bended periodically, and the quantitative calculations of macrosegregation were also made in the process of the continuous casting. The solute distribution along the thickness direction of the slabs was obtained, which verified the theoretical calculation. The effect of the bulge size, solidification speed, and solidification shrinkage speed on macrosegregation of the slabs was calculated. It can be concluded that normal segregation and negative segregation alternatively appear as a result of the bulge. The normal segregation exponentially depends on the bulge size, and the negative segregation linearly depends on the bulge size. The extent of the normal segregation is greater than that of the negative segregation when the bulge size is the same. The macrosegregation of the same position along the thickness direction of the slabs changes in a sine wave with increasing the solidification rate, and the amplitude is larger at the casting blank center. The normal segregation linearly decreases with increasing the solidification shrinkage speed, and when the solidification shrinkage speed exceeds a critical value, the segregation appears negatively and increases linearly. 相似文献
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Yu. G. Dorofeev G. A. Dreev V. N. Mishchenko 《Powder Metallurgy and Metal Ceramics》1988,27(9):681-684
Conclusions A constriction is a characteristic HF defect of stepped blanks produced by nonsynchronous upsetting. Its size grows with increasing width of the clearance between the blank and the tool, with decreasing blank density, and with increasing step height. Constriction formation can be prevented by ensuring that the actual stepped parts and blanks have identical fillets in the transition zones, whose radii are not less than three times the anticipated constriction size.Translated from Poroshkovaya Metallurgiya, No. 9(309), pp. 6–9, September, 1988. 相似文献
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目前待矫直板材缺陷类型及程度的判断仍然是依赖现场工作人员的经验,具有很大的不确定性。为了获得待矫直板材残余应变(应力)的大小及分布,根据薄板大挠度屈曲理论和最小势能原理,建立了基于浪形几何参数的反解计算模型。通过实测的浪形几何参数和预设挠曲函数,对引起边浪、中浪(肋浪)等典型的浪形缺陷的残余应变(应力)进行求解,并与实测值进行对比。结果表明,残余应变(应力)的分布与浪形几何形状相对应,但压应力宽度略小于屈曲宽度,即紧邻压应力的拉应力区也产生了挠曲;几何非线性及后屈曲强度对浪形状态的影响是显著的;求解过程与板厚无关,所需几何参数较少,便于现场应用。 相似文献