Effect of wire diameter compression ratio on drawing deformation of micro copper wire

A crystal plasticity finite element model was developed for the drawing deformation of pure copper micro wire,based on rate-dependent crystal plasticity theory.The impact of wire diameter compression ratio on the micro-mechanical deformation behavior during the wire drawing process was investigated.Results indicate that the internal deformation and slip of the drawn wire are unevenly distributed,forming distinct slip and non-slip zones.Additionally,horizontal strain concentration bands develop within the drawn wire.As the wire diameter compression ratio increases,the strength of the slip systems and the extent of slip zones inside the deformation zone also increase.However,the fluctuating stress state,induced by contact pressure and frictional stress,results in a rough and uneven wire surface and diminishes the stability of the drawing process.

Modeling asymmetric fracture mechanics of Mg alloy wire in drawing process

In this study,a numerical analysis was conducted on the ductile fracture of a 2-mm diameter Mg-1Zn-0.5Mn-0.5Sr-0.1Ca alloy wire during drawing.The hexagonally close-packed crystal structure of Mg alloys causes asymmetric fracture behavior,especially in the compression region.The aim of this study is to develop a comprehensive damage model for Mg alloy wire that accurately predicts ductile fracture,with a focus on the compression region.A novel experimental method was introduced to measure the ductile fracture of Mg alloy wires under different stress states.The wire drawing process was simulated using the Generalized Incremental Stress-State dependent damage(GISSMO)Model and the Semi-Analytical Model for Polymers(SAMP)model.The damage model's prediction and the experimental results were found to be in excellent agreement,especially in determining crack initiation.Computational analysis established a safe zone diagram for die angle and reduction ratio,and experimental validation confirmed the feasibility of this approach.The proposed damage model can provide a practical and reliable analysis for optimizing the drawing process of Mg alloy wire.

Influence of drawing process parameters on forming of micro copper tube with straight grooves

Using high-speed oil-filled spinning method,high quality micro copper tube with straight grooves（MCTSG） with an outer diameter of 6 mm was obtained.Then,MCTSG with an outer diameter of 3-6 mm was fabricated successfully by multi-pass drawing processing method.The influence of drawing parameters on the forming of micro straight grooves was investigated based on the forming mechanism.The results show that the values of groove depth and width decrease,while the wall thickness increases as the drawing diameter decreases.At the same time,the groove depth and width increase,while the wall thickness decreases as the die angle increases.The drawing force increases as the reduction increases.Excessive copper tube reduction may results in groove folding and segmental teeth.The drawing force decreases firstly and then increases with the increases in die angle.When the die angle α is 16°,the drawing force is the smallest,indicating 16° is the optimal angle.

Microstructure and texture of commercially pure titanium in cold deep drawing

The development of microstructure and texture during cold deep drawing of commercially pure titanium（CP-Ti） was investigated.Three parts,stretching region,drawing region and flange region,were sequentially formed in the deep drawing process of the hemispheric surface part,with reference to deformation modes and strain regimes.Results show that the plastic strain is accommodated by dislocation slip and deformation twinning in the whole deep drawing process.The texture of the CP-Ti sheet and its drawn part consists of rolling texture component and recrystallization texture component.The intensity and type of the initial texture varied during the drawing process are related to the production of deformation twinning and dislocation slip.Twinning weakens the initial texture by randomizing the orientations of crystals,especially for the recrystallization texture.The recrystallization texture in the drawing region disappears due to the significant forming of twinning.Furthermore,over drawing would result in the predominance of dislocation slip and the texture is strengthened.

Texture evolution and its simulation of cold drawing copper wires produced by continuous casting

The texture evolution of cold drawing copper wires produced by continuous casting was measured by X-ray diffractometry and electron back-scatter diffractometry,and was simulated using Taylor model.The results show that in the drawn poly-crystal copper wires produced by traditional continuous casting,111 and 100 duplex fiber texture forms,and with increasing strain,the intensities of 111 and 100 increase.In the drawn single-crystal copper wires produced by Ohno continuous casting,100 rotates to 111,and there is inhomogeneous distribution of fiber texture along radial direction of the wires,which is caused by the distribution of shear deformation.Compared with 100,111 fiber texture is more stable in the drawn copper wires.Comparison of the experimental results with the simulated results shows that the simulation by Taylor model can analyze the texture evolution of drawn copper wires.

Effect of electropulsing on deformation behavior of Ti-6Al-4V alloy during cold drawing

Electron backscattered diffraction （EBSD） and transmission electron microscopy （TEM） were used to investigate effect of electropulsing on microstructure and texture evolution of Ti-6Al-4V during cold drawing. Research results demonstrate that the electropulsing treatment （EPT） can enhance the deformability of the grains with unfavorable orientations, which makes the compatibility of deformation among grains much better. A comparison in texture evolution between conventional cold drawing and EPT cold drawing indicates that the EPT promotes prismatic 〈a〉 slip moving, restricts pyramidal 〈c＋a〉 slip occurring and accommodates the deformation with c-component by grain boundary sliding. The fraction decrease of low-angle grain boundaries for samples deformed with EPT reveals that the application of electropulsing restricts the formation of the incidental dislocation boundaries and the geometrically necessary boundaries.

Sensitivity of springback and section deformation to process parameters in rotary draw bending of thin-walled rectangular H96 brass tube

In order to study the effects of the process parameters on springback and section deformation, a sensitivity analysis model was established based on the combination use of the multi-parameter sensitivity analysis method and the springback/section deformation prediction finite element model, and by using this model the sensitivities of the springback and the section deformation to process parameters were analyzed and compared. The results show that the most sensitive process conditions for springback angle are the boost speed and the pressure of pressure die, and the most sensitive process condition for section deformation is the number of cores. When the clamp force, the boost speed and the pressure of pressure die are utilized to control section deformation, the effect of these process parameters on springback should be considered. When the process parameters are mainly used to control springback, the effect of these process parameters on the section deformation should be always considered.

Effects of stress state on texture and microstructure in cold drawing-bulging of CP-Ti sheet

Three different stress states of the combination of tensile（t） stress and compressive（c） stress,t t,t c and t c c,exist in the deformed commercially pure titanium（CP-Ti） sheet during cold drawing-bulging.The textures and microstructures in the different stress state regions were investigated by means of XRD and TEM analysis.Similar development of texture and microstructure is achieved with less thickness strain under multiaxial stresses in drawing-bulging than in cold rolling.The results show that texture and microstructure are much sensitive to multiaxial stresses.Twinning is more easily activated under compressive stress than tensile stress.Prism a slip is heavily affected by tensile stress,resulting in a remarkable change of the intensity of（0°,35°,0°） texture,while pyramidal c＋a slip,forming（20°,35°,30°） texture,weakens with the increase of thickness strain in spite of stress state.

基于Arc/Info与CorelDraw的土地利用图的制作

探讨在Arc/Info和CorelDraw环境中土地利用图的制作方法。这种方法结合了Arc/Info软件强大的图形编辑功能和Corel Draw软件完美的绘图功能,使在土地利用图的制作过程中,工作量大大减少,作图质量大大提高。

Application of ultra-smooth composite diamond film coated WC-Co drawing dies under water-lubricating conditions

A specific revised HFCVD apparatus and a novel process combining HFCVD and polishing technique were presented to deposit the micro-and nano-crystalline multilayered ultra-smooth diamond（USCD） film on the interior-hole surface of WC-Co drawing dies with aperture ranging from d1.0 mm to 60 mm.Characterization results indicate that the surface roughness values（Ra） in the entry zone,drawing zone and bearing zone of as-fabricated USCD coated drawing die were measured as low as 25.7,23.3 and 25.5 nm,respectively.Furthermore,the friction properties of USCD films were examined in both dry sliding and water-lubricating conditions,and the results show that the USCD film presents much superior friction properties.Its friction coefficients against ball-bearing steel,copper and silicon nitride balls（d4 mm）,is always lower than that of microcrystalline diamond（MCD） or WC-Co sample,regardless of the lubricating condition.Meanwhile,it still presents competitive wear resistance with the MCD films.Finally,the working lifetime and performance of as-fabricated USCD coated drawing dies were examined under producing low-carbon steel pipes in dry-sliding and water-lubricating conditions.Under the water-lubricating drawing condition,its production significantly increases by about 20 times compared with the conventional WC-Co drawing dies.

Flexible die drawing of magnesium alloy sheet by superimposing ultrasonic vibration

Combining solid granule medium forming technology with ultrasonic vibration plastic forming technology, ultrasonic vibration granule medium forming （UGMF） technology was proposed. To reveal the effect of ultrasonic vibration on flexible-die deep drawing, an ultrasonic vibration with a frequency of 20 kHz and a maximum output of 1.5 kW was on the solid granule medium deep drawing of AZ31B magnesium alloy sheet. The results revealed that ultrasonic vibration promotes the pressure transmission performance of the granule medium and the formability of the sheet. The forming load declines with the ultrasonic amplitude during the drawing process as a result of the combined influence of the ＂surface effect＂ and the ＂softening＂ of the ＂volume effect＂.

Reverse deep drawability of 5A06 aluminum alloy plate at elevated temperatures

In order to avoid the occurrence of fracture at room temperature in reverse deep drawing of aluminum alloy plate, the warm reverse deep drawing method was proposed. The experiments were conducted at room temperature, 280 and 360 ℃ with a 4.5 mm thick 5A06 aluminum alloy plate. The effect of temperature, blank-holding force and gap on the fracture and wrinkle of the reverse deep drawing process was investigated. A fully coupled thermal-mechanical simulation was carried out to obtain the stress distribution through the commercial software of Abaqus/Explicit. The results show that the fracture is avoided at 280 ℃ since the bending-induced stress gradient in the transient area between the inside corner and the straight wall decreases from 505 MPa at RT to 72 MPa at 280 ° C. Although the fracture is avoided as the temperature increases, the wrinkle occurs at the outside die corner at temperature over 280 ° C, where the circumferential compressive stress becomes larger than that at the inside. As the temperature increases to 360 ℃, the fracture occurs due to the excessive softening, the tensile stress in the straight wall reaches rapidly to the tensile strength at the beginning of reverse deep drawing. When 1.5t （t=4.5 mm） blank holding gap is applied at 280 ℃, both the fracture and wrinkle can be avoided, and 420 mm deep cups are drawn successfully.

Effects of tribological behavior of DLC film on micro-deep drawing processes

To decrease the size effects of friction in microforming, three kinds of surface coatings, such as diamond-like carbon（DLC）, TiN and MoS2, were deposited on surfaces of dies with plasma based ion implantation and deposition（PBII D） method and magnetron sputtering technique, respectively. The tribological behavior of surface coatings was analyzed considering plastic deformation of specimen at contact interface. The analyses indicate that there is a lower coefficient of friction（COF） and a high wear resistance under the condition of large strain/stress when using the DLC film. The graphitization of DLC film occurs after 100 times of tests. The mechanism of graphitization was analyzed considering energy induced by friction work. The effects of DLC film properties on qualities of micro-deep drawn parts were investigated by analyzing the reduction of wall thickness, etc. The results indicate that DLC film is very helpful for improving the qualities of the micro-parts.

A Mapping Technique to Draw Resistivity Isocontours for Slice-of-Silicon Monocrystal

A resistivity distribution with a space of 3mm between test points was measured on a slice-of-silicon monocrystal （diameter 75mm） using an inclined four-point probe. This paper has determined the number of resistivity divisions and their separations by statistical methods and introduced fuzzy mathematics to place the data into different fuzzy sets, after choosing the exponent function as a membership function for fuzzy sets and suitable values of thresholds. One fuzzy set corresponds to one resistivity isocontour. Then,the resistivity isocontours can be drawn with a definite separation and fi- nally shown in a map with MATLAB. The deviation of resistivity data on an isocontour is small and there are few residual test points without connections. So, the connection of the isocontours are high-quality and useful in application for instructing practical production.

基于Visio Drawing Control控件的图形化潮流计算软件开发

针对VC,Delphi等工具开发电力系统分析计算软件图形可视化的缺陷,提出并研究了一种基于VisioDrawing Control图形控件,利用VC进行二次开发的图形化电力系统潮流计算软件开发的技术,研究了基于该控件的图形化建模方法及电网拓扑结构的自动识别,开发了实用的电力系统图形化潮流计算软件.实践表明,基于Visio Drawing Control的二次开发技术为图形化电力系统潮流计算软件的开发提供了新的有效的途径.

Graphical Simulator for Chinese Ink-Wash Drawing

Simulating the traditional painting art by computer graphics is a challenging and attractive subject. Basing on the experience in the ink wash drawing, in this paper, we expound the artistic characters of ink wash painting and particularly analyze the characteristics of the materials used in the ink wash drawing and the relationships between them. A simulation model is presented and some typical visual effects of the ink wash painting are realized.

Effect of friction coefficient in deep drawing of AA6111 sheet at elevated temperatures

The effect of friction coefficient on the deep drawing of aluminum alloy AA6111 at elevated temperatures was analyzed based on the three conditions using the finite element analysis and the experimental approach.Results indicate that the friction coefficient and lubrication position significantly influence the minimum thickness,the thickness deviation and the failure mode of the formed parts.During the hot forming process,the failure modes are draw mode,stretch mode and equi-biaxial stretch mode induced by different lubrication conditions.In terms of formability,the optimal value of friction coefficient determined in this work is 0.15.At the same time,the good agreement is performed between the experimental and simulated results.Fracture often occurs at the center of cup bottom or near the cup corner in a ductile mode or ductile-brittle mixed mode,respectively.

Influence of blank holder type on drawability of 5182-O aluminum sheet at room temperature

To study the influence of blank holder type on the drawability of 5182-O aluminum sheet at room temperature, the flat blank holder and curved blank holder were employed during the deep drawing process. The microstructures were characterized by optical microscopy （OM）. The results reveal that the limiting drawing ratio （LDR） of 5182-O aluminum alloy sheet is 1.7 using the flat blank holder. The drawn cup have severe earring. Compared with using flat blank holder, the LDR of 5182-O aluminum alloy sheet is enhanced to 2.0 using curved blank holder. In addition, the earring ratio also reduces and flange wrinkling is prevented when the curved blank holder is used. These are due to a more uniform sheet flow in different directions with curved blank holder.

Analysis of elliptical cup drawing process of stainless sheet metal

Prandtl-Reuss flow rule and Hill’s yield criterion were adopted and combined with the concept of finite deformation theory, updated Lagrangian formulation, and a three-dimensional finite element analytical model was established by application of quadrilateral four-node degenerated shell elements coupling into a rigid matrix to deal with the sheet metal forming problems. The fractured thickness of a specimen obtained from a simple tension test was used to be the fracture criterion for the numerical analysis to explore the relationship between punch load and stroke, the thickness distribution, the deformation history and the forming limit of work-piece in the elliptical cup drawing process. The numerical analysis and experiment results show that the punch load increases with the increase of punch stroke, and when the load reaches its maximum, the blank continues to deform with the increase of the punch stroke, resulting in a reduced load until the extension is completed. The minimum thickness of the work-piece concentrates in the contact region of the work-piece and long axis of the punch due to the smaller radius of the curvature of the long axis than the short axis. So the blanks bore the maximum tensile stress in the long axis. Through the limit drawing ratio defined by perimeter of the elliptical punch, the limit drawing ratio of this elliptical cup drawing is defined to be 2.136.

海外项目shop drawing的理解

通过对海外项目shop drawing(细化图)的理解,阐述了shop drawing的定义以及绘制shop drawing过程中需要注意的问题。通过实例分析,为同类型国际港口工程中细化设计提供参考和借鉴。