高应变率成形极限图测试与仿真研究进展

高应变率成形是一种在极短时间内释放高能量而使金属变形的成形方法,研究表明高应变率能显著提高多种金属材料的成形极限能力。通过高速杯突实验绘制成形极限曲线,可反映金属在高应变率下的成形能力,从而指导冲压设计。文中介绍了目前常用的几种高速杯突实验设备,包含气压、液压和电磁等驱动方式,并对高应变率下的成形极限图进行了分析和总结,文中还介绍了高速杯突成形目前常用模拟仿真方法,最后对高应变率成形极限图测试研究进行了展望。

Formation mechanism of nanopores in dense films of anodic alumina

Constant-current anodization of pure aluminum was carried out in non-corrosive capacitor working electrolytes to study the formation mechanism of nanopores in the anodic oxide films.Through comparative experiments,nanopores are found in the anodic films formed in the electrolytes after high-temperature storage(HTS)at 130°C for 240 h.A comparison of the voltage-time curves suggests that the formation of nanopores results from the decrease in formation efficiency of anodic oxide films rather than the corrosion of the electrolytes.FT-IR and UV spectra analysis shows that carboxylate and ethylene glycol in electrolytes can easily react by esterification at high temperatures.Combining the electronic current theory and oxygen bubble mold effect,the change in electrolyte composition could increase the electronic current in the anodizing process.The electronic current decreases the formation efficiency of anodic oxide films,and oxygen bubbles accompanying electronic current lead to the formation of nanopores in the dense films.The continuous electronic current and oxygen bubbles are the prerequisites for the formation of porous anodic oxides rather than the traditional field-assisted dissolution model.

工业型煤炉前成形技术

炉前成形技术是链条炉排工业锅炉实现“型煤燃烧”的一项关键技术。在链条炉的炉前煤斗中安装辊式成形机,轧辊由电机经减速机拖动。型煤产量可用改变型辊转速使之与炉排走速、煤层厚度及锅炉负荷变化相适应,成形率与型煤强度可用改变弹簧机构来调节,使之满足型煤燃料层的层燃要求,弹簧结构兼具保安作用。炉前成形机性能指标:型辊直径200～300mm;

制粒工艺参数对制粒效果影响的试验研究

采用3种调质温度和2种规格的环模进行向中鸡料制粒生产,分别测定各调质温度下的入模粉料淀粉糊化率及各种组合条件下的产品淀粉糊化率、成形率和粉化率,结果表明:(1)入模粉料的淀粉糊化率与调质温度显著正相关;(2)产品的淀粉糊化率随调质温度升高而升高,但环模规格的影响则不显著;(3)制粒成形率与调质温度的关系取决于环模规格,而环模规格与成形率显著相关,环模孔径越小、长径比越大,成形率越高;(4)产品粉化率与调质温度负相关,且随环模孔径的减小和长径比的增大而减小.

夏黑葡萄双“十”字架“T”字树形培育试验初报

夏黑葡萄双"十"字架"T"字树形培育,采用主蔓摘心与主蔓弯曲两种方式。试验结果表明,主蔓摘心当年成形率、次年成花率、次年产量都高于主蔓弯曲。

离心球墨铸铁管渗漏机理分析及预防措施

针对球墨铸铁管的渗漏特点,分析渗漏的主要原因来源于夹渣、针孔、裂纹等铸造缺陷,严重影响铸铁管的成形率和水压合格率。通过研究与分析,结合生产实际,提出了解决这些缺陷的预防措施。

Creep age forming of 2124 aluminum alloy with single/double curvature

In order to investigate the springback rules, the variation characteristics of physical property and microstructure in bending creep age forming process, a series of creep forming tests of 2124 aluminum alloy were conducted based on three kinds of single and double curvature forming tools. The results show that the spingback rate would be the minimum under the optimal coupling conditions among the temperature, aging time and internal stress state of material. Difference exists in the two directions of the formed sample with double curvature, but the curvature variation keeps the same. Yield strength, ultimate tensile strength and fracture toughness of the double curvature formed sample appear to be higher than those of the single curvature formed sample under the same aging condition, but the elongation and the anisotropy are opposite.

Microstructure and properties of electronic packaging box with high silicon aluminum-base alloy by semi-solid thixoforming

The electronic packaging box with high silicon aluminum-base alloy was prepared by semi-solid thixoforming technique.The flow characteristic of the Si phase was analyzed.The microstructures of different parts of the box were observed by optical microscopy and scanning electron microscopy,and the thermophysical and mechanical properties of the box were tested.The results show that there exists the segregation phenomenon between the primary Si phase and the liquid phase during thixoforming,the liquid phase flows from the box,and the primary Si phase accumulates at the bottom of the box.The volume fraction of primary Si phase decreases gradually from the bottom to the walls.Accordingly,the thermal conductivities of bottom center and walls are 107.6 and 131.5 W/（m·K）,the coefficients of thermal expansion（CTE） are 7.9×10-6 and 10.6×10-6 K-1,respectively.The flexural strength increases slightly from 167 to 180 MPa.The microstructures and properties of the box show gradient distribution overall.

新型充液冲击冲裁技术

充液冲击复合成形技术是一种高能率成形方法,适用于薄板加工。该文提出一种新型充液冲击冲裁方法,即在充液成形完成零件特征后,再以刚性锥形冲头高速向下运动压缩液体,产生的瞬时高压以冲击波的形式作用在板坯上进行冲裁。其中,脉冲压力作用时间仅0.001s。充液冲击冲裁力作用形式数值模拟及1mm低碳钢板冲裁实验结果表明,充液冲击冲裁中,极高瞬时压力以波的形式作用,板料获得的动能使其在冲击波压力低于其变形抗力和冲击波压力停止作用后仍能继续变形,在坯料中形成较大拉应力,而剪应力由坯料自身向下运动形成。这两种应力使坯料产生缩颈和裂纹,最终断裂分离。因此,充液冲击复合成形技术冲裁与传统刚性凸模剪应力作用有本质区别。采用液体作为凸模,对模具制造精度要求大幅降低,且冲裁件断面整齐、几乎无毛刺,尺寸精度满足要求。

9KL-380型秸秆饲料压块机的试验研究

就压块机试验情况进行了分析；采用了3种压辊直径，通过电磁调速电机作为试验动力，以验证不同压辊直径对成块质量及生产率的影响，进而确定最佳结构参数。另外，对物料最佳成块水分含量进行了系统的试验，确定了成块时物料水分控制范围及操作程序。

Formability determination of AZ31B tube for IHPF process at elevated temperature

Ring hoop tension test and tube bulging test were carried out at elevated temperatures up to 480 ℃to evaluate the formability of AZ31B extruded tube for internal high pressure forming （IHPF） process. The total elongation along hoop direction and the maximum expansion ratio （MER） of the tube were obtained. The fracture surface after bursting was also analyzed. The results show that the total elongation along hoop direction and the MER value have a similar changing tendency as the testing temperature increases, which is quite different from the total elongation along axial direction. Both the total elongation along hoop direction and the MER value increase to a peak value at about 160 ℃. After that, they begin to decrease quickly until a certain rebounding temperature is reached. From the rebounding temperature, they begin to increase rapidly again. Burnt structure appears on the fracture surface when tested at temperatures higher than 420 ℃. Therefore, the forming temperature of the tested tube should be lower than 420 ℃, even though bigger formability can be achieved at higher temperature.

不同投叶量对珠形茶造形技术的影响

投叶量是珠形茶造形工艺最关键的制茶因子之一,为了探索珠形茶造形阶段的合理投叶量,把3个造形阶段按A、B、C排定,分别采用多种投叶方式进行试验设计,通过对比并分析3个造形阶段的不同投叶量对珠形茶造形工艺的影响作用。试验结果表明:适宜珠形茶第一阶段造型的投叶量分别为3kg,第二阶段造型5kg,第三阶段造型8kg。在此投叶量下加工造型,不仅操作更易控制,且更利于珠形茶成形率和外形紧结度的提高。

A method for calculation of ion distribution in reaction system forming hydroxide

A formula was proposed to calculate the distribution of metal ions quantitatively in chemical reaction system forming hydroxide where precipitation and complex are formed together. The effects of some factors on formation of precipitation and complex were investigated, and the corresponding precipitation rates of zinc, iron （III）, aluminum, copper and magnesium were calculated. As a result, it shows that the proposed formula is reliable. By the proposed formula, the existence state of metal ions in hydroxides reaction system with any metal ions can be well described and the effects of some factors on the distribution of metal ions were determined.

钾长石代替钠长石熔制玻壳料的生产实践

针对玻壳料变化大、柔韧性差、玻壳成形率低等问题 ,在原材料中用钾长石代替钠长石 。

免烧砖生产线

利用各种工矿废渣生产免烧砖成套设备及工艺技术,是国家墙体材料改革重点项目,由我所设计人员及制造厂家联合研制完成。其主机构思新颖、双向加压,砖坯成形率高,质量好,是我国墙体材料改革的理想设备;具有国内先进水平。

Formation mechanism and organizational controlling of ultra-fine-grain copper processed by asymmetrical accumulative rolling-bond and annealing

The initial copper with large grain sizes of 60-100 μm was processed by six passes asymmetrical accumulative rolling-bond （AARB） and annealing, the ultra-fine-grained （UFG） copper with grain size of 200 nm was obtained, and the microstructures and properties were studied. The results show that there are large sub-structures and also texture component C for the UFG copper obtained by six passes AARB, possessing high strength and microhardness in company with poor elongation and conductivity. Thereafter, the UFG copper was annealed at 220 °C for 35 min, in which the sub-structures disappear, the grain boundaries are composed of big angle grain boundaries, and the textures are composed of a variety of texture components and parts of twins. Compared with the UFG copper obtained by six passes AARB, the tensile strength and yield strength for the UFG copper obtained by six passes AARB and annealing at 220 °C for 35 min are decreased slightly, the elongation and conductivity are improved obviously.

Yield Modeling of Rectangular Defect Outline

In integrated circuits, the defects associated with photolithography are assumed to be in the shape of circular discs in order to perform the estimation of yield and fault analysis. However,real defects exhibit a great variety of shapes. In this paper,a novel yield model is presented and the critical area model of short circuit is correspondingly provided. In comparison with the circular model corrently available, the new model takes the similarity shape to an original defect, the two-dimensional distributional characteristic of defects, the feature of a layout routing and the character of yield estimation into account. As for the aspect of prediction of yield, the experimental results show that the new model may predict the yield caused by real defects more accurately than the circular model does. It is significant that the yield is accurately estimated and improved using the proposed model.

Microstructure and properties of SiC_p/Al electronic packaging shell produced by liquid-solid separation

The electronic packaging shell of high silicon carbide （54%SiC, volume fraction） aluminum-based composites was produced by liquid-solid separation technique. The characteristics of distribution and morphology of SiC as well as the shell’s fracture surface were examined by optical microscopy and scanning electron microscopy, and the thermo-physical and mechanical properties of the shell were also tested. The results show that Al matrix has a net-like structure while SiC is uniformly distributed in the Al matrix. The SiCp/Al composites have a low density of 2.93 g/cm^3, and its relative density is 98.7%. Thermal conductivity of the composites is 175 W/（·K）, coefficient of thermal expansion （CTE） is 10.3×10^-6 K-1 （25-400 ℃）, compressive strength is 496 MPa, bending strength is 404.5 MPa, and the main fracture mode is brittle fracture of SiC particles accompanied by ductile fracture of Al matrix.Its thermal conductivity is higher than that of Si/Al alloy, and its CTE matches with that of the chip material.

3D modeling and deformation analysis for electromagnetic sheet forming process

Electromagnetic forming （EMF） is a high-speed forming method which can be quite effective in increasing the forming limits of metal sheet. However, the EMF process is complicated due to magnetic-structure coupling analysis. Numerical simulation offers an opportunity to overcome the problem. Nevertheless, most present models for EMF process are limited to 2D axisymmetric model. So, a three-dimensional （3D） finite element model was established to analyze the electromagnetic sheet bulging. The contact between the sheet and the die and the effect of sheet deformation on the magnetic field analysis were both taken into consideration during the forming process. The simulation results of deflection at the sheet center and 20 mm away from the center were in agreement with the experimental ones. The plastic strain energy and plastic strain were analyzed.