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.

Advanced simulation of die wear caused by wire vibrations during wire-drawing process

An advanced simulation that considers the effect of wire vibrations was proposed for predicting accurately wear profiles of a die used in a wire-drawing process.The effect of wire vibrations,the changes in the wear profiles,and the generation of ringing during die approach were investigated by this simulation.Wire vibrations occurring between the die and the drum are governed by a partial differential equation called the wave equation,which is a function of the wire length,tension,density,and initial wire velocity.The wire-drawing process was simulated by the commercial code Abaqus FEA,and the die wear profiles were predicted by Archard’s wear model.The predicted profiles were compared with measured profiles of a worn drawing die after producing 5 t of AISI 1010 wire;the die was made of tungsten carbide with a Brinell hardness of HB 682.The profiles predicted by considering the effect of wire vibrations are in good agreement with the experimental data,indicating that the advanced simulation can be used to accurately predict the die wear profiles when ringing is observed during die approach.

Deep Drawing Process Using a Tractrix Die for Manufacturing Liners for a CNG High-Pressure Vessel(Type Ⅱ)

The liner of a CNG pressure vessel is manufactured by a DDI(deep drawing and ironing)process for the cylinder part,which is a continuous process that includes a drawing process to reduce the diameter of the billet and a subsequent ironing process to reduce the thickness of the billet.A tractrix die used in the 1^(st) deep drawing allows the blank to flow smoothly by decreasing the punch load and radial tensile stress occurring in the workpiece.It also increases the draw ratio compared to conventional dies,but it causes forming defects.In this study,a shape coefficient(S_(c))is proposed for the tractrix die using the blank diameter(D_(0)),inflow diameter of the workpiece(d_(i)),and inflow angle of the workpiece(θ)for design of the tractrix die.The effects of the thickness and inflow angle of the workpiece on wrinkling and folding were investigated through FEA.Also,a discriminant is proposed for the relative radial stress(σ)generated during the deep drawing process using the tractirx die and used to predict fracture.Based on the results,the blank thickness,the draw ratio,and the inflow of the workpiece angle in the 1^(st) deep drawing process are suggested,and the number of operations in the DDI process was reduced from 6 to 4.This improves the productivity and reduces the manufacturing cost.

Fabrication and application of nano/microcrystalline composite diamond coated drawing dies using alternative carbon sources

Nano/microcrystalline composite diamond films were deposited on the holes of WC-6%Co drawing dies by a two-step procedure using alternative carbon sources, i.e., methane for the microcrystalline diamond（MCD） layer and acetone for the nanocrystalline diamond（NCD） layer. Moreover, the monolayer methane-MCD and acetone-NCD coated drawing dies were fabricated as comparisons. The adhesion and wear rates of the diamond coated drawing dies were also tested by an inner hole polishing apparatus. Compared with mono-layer diamond coated drawing die, the composite diamond coated one exhibits better comprehensive performance, including higher adhesive strength and better wear resistance than the NCD one, and smoother surface（Ra=65.3 nm） than the MCD one（Ra=95.6 nm） after polishing at the same time. Compared with the NCD coated drawing die, the working lifetime of the composite diamond coated one is increased by nearly 20 times.

Effect of die cavity dimension on micro U deep drawing behaviour with T2 foil

The strips U deep drawing experiments were carried out to study the effect of die cavity dimension with an extension machine manufactured by SANS company. The effects of parameters were analyzed in deep drawing process under different experimental conditions, such as punch load, reduction of thickness, angle of U part and surface quality. The experiment results show that the punch load increases with the decrease of female radius, and larger blank holder force enlarges the range of increasing. With the increasing of blank holder force, the angle of U part increases, and the reduction of foil thickness at the corner becomes larger. Obvious scratch and accumulation at the die cavity corner were observed by SEM. The investigation results indicate that micro U deep drawing of foil is affected by micro die cavity dimension.

Wear Characteristics of Zirconia Toughened Ceramic Drawing Dies

Wear resistance of several zirconia toughened ceramics in comparison with a metal-ceramic Co-WC has been studied in drawing wire field test. Result indicates that the harder the ceramic die, the longer the service life. Excellent wear resistance of ceramic die is obtained with a very high hardness (19 GPa). The service life is nearly three times that of Co-WC die. SEM observation on wear surfaces showed that material removal is mainly caused by plastic flow and ploughing process. But when the ceramic is composed of zirconia, alumina and some titanium carbide, micro-chipping and tribochemical reaction take place, and wear rate increases. Wear and friction induced martensite was detected by XRD. The T-M (tetragonal to monoclinic) phase transformation has a contribution to inhibiting microfracture.

THE CURVILINEARINTEGRAL PROBLEMS TO VELOCITY FIELD FOR DRAWING THROUGH PARABOLIC DIES

n this paper with Von Karmanis basic assumptions a kinematically admissible continuous velocity field has been established to drawing through parabolic dies (or called trumpet dies). Then by. using the curvilinear and the integral as a function of the upper limit an upper bound analytical solution of the drawing stress is obtained.

Effect of Anisotropy,Temperature,Strain Rate on Deep Drawing Using Conical Die

This paper covers the role of anisotropy,temperature,and strain rate on the flow behavior of the material when a conical die is used instead of conventional blank holder.The effect of anisotropy was investigated using Lankford’s coefficient(r)in three directions(0°,45°,and 90°).The effect of working temperatures(Room temperature,100°C-300°C)on drawing stress and strain rate sensitivity on punch pressure were also investigated in detail.ANSYS APDL was used to investigate the effects of temperature,strain rate and anisotropy.The simulation results have confirmed that the strain variation in the direction of r0 and r45 are more than the variation of r90.

Determination of a Drawing Die's Cone Angle at a Small Compression Ratio Based on the Upper Bound Theory

The value of a drawing die＇s cone angle has great influence on wire drawing. In order to determine the optimum value of a drawing die＇ s cone angle, the plastic deformation power Wi, shear deformation power Wi and friction power of contact surface Wf were calculated using the upper bound theory with a reasonable and movement permitted velocity field according to the related characteristics. Then the relation between half cone angle and unit drawing force was obtained and it was compared with the result with the spherical velocity field. The relative error of the two near the optimal value is only about 0. 26% through comparing with existing calculated results. Finally, in an ABAQUS environment the finite element modal of the wire rod with 12. 5 mm diameter in first drawing pass was established and the axial drawing force in different cone angles was obtained using the ABAQUS/Explicit explicit integration method. The finite element method （FEM） results verify the results using the upper bound theory and this indicated that the velocity field and the relation between half cone angle and unit drawing force reasonable.

Design, Fabrication and Experimentation of a Deep Drawing Machine

This paper presents the work implemented in designing, fabricating and operating a model of a cheap hydraulic DDM （deep drawing machine）, which is currently utilized in the manufacturing processes lab in the IED （Industrial Engineering Department） at An-Najah National University. The machine is used to conduct different experiments related to the deep drawing process. This work was implemented in three stages： the first was the design stage, in which all design calculations of the DDM elements were completed based on the specifications of the product （cup） to be drawn; the second was the construction stage, in which the DDM elements were fabricated and assembled at the engineering workshops of the university; the last was the operating and experimentation stage, in which the DDM was tested by conducting different experiments. The experience gained from designing and constructing such a mechanical lab equipment was found to be successful in terms of obtaining practical results that agree with those available in literature, cost-effective relative to the cost of a similar purchased equipment, as well as enhancing students＇ abilities in understanding the deep drawing process in particular and machine elements design concepts in general.

火锅菜盆复合模设计

根据火锅菜盆的尺寸、结构和材料厚度,对其冲压工艺进行分析,并设计了“落料+第1次成形+拉深”复合模、第2次成形单工序模、侧冲孔单工序模。在复合模中,120°的斜边可视为拉深工序的压边圈,将第1次成形120°夹角的工序排在拉深工序前。在第2次成形70°夹角的单工序模的下模中设计了活动顶板,与上模的成形凸模将120°的斜边压住,防止120°的斜边变形。在“落料+第1次成形+拉深”复合模和第2次成形单工序模中,在下模成形零件的底部设置橡胶垫块,在上模向下运动时橡胶垫块的弹力将材料顶住,同时给上模向下运动腾出空间,防止模具零件卡死。

U型框类零件双向拉深成形研究

针对U型框类零件成形质量不稳定、修整手工量大等问题,通过对零件结构的分析研究,借助CATIA对其进行了工艺补充面设计,并借助数值模拟对成形过程进行了仿真,研究了双向拉深成形工艺,设计了一种特有传力方式的双向拉深模具结构;选取凸凹模间隙、摩擦因数、压边力及拉深速度4个因素为优化变量,通过正交试验得出最优工艺参数组合,即压边力大小为30 kN、摩擦因数为0.1、凸凹模间隙为1.6 mm、拉深速度为6000 mm·s^(-1);最后针对拉深后回弹现象,对校正模进行了分析和设计并修整。生产试验表明,此模具结构可以很好地改善零件成形质量,提高效率并满足生产及设计要求。

利用Pro/DIEFACE优化汽车覆盖件拉深模的拉深方向

从汽车覆盖件拉深模拉深方向的设计现状谈起 ,分析了目前拉深方向仅凭经验设计无法进行优化的两个主要原因 :拉深方向的判别指标无法实际应用和拉深方向的难以改变 ,进而结合Pro/Engineer中的专业模块Pro/DIEFACE所提供的设计和分析功能 ,讲述了如何利用Pro/DIEFACE将这两个问题合理地解决 ,从而实现了拉深方向的优化。

轴承坯料机械手轴盖3D多工位级进模设计

针对轴承坯料机械手轴盖制件一套三件的成套冲压成型生产要求,运用3D设计软件UG设计了一副11工位连续级进模用于轴盖成套制件的生产。模具中所设计的11工位包括冲孔、落料、拉深、翻边、侧切、侧冲孔等工艺成型手段,模具达到的效果是材料利用率达到64.23%,制件生产效率可达45套/min,模具制造成本降低5%。相比于传统多工序多套单冲模成型工艺,生产效率提高10倍以上。模具中,使用1次拉深成型、3次精修,对多级拉深成型件进行加工能有效降低制件加工难度;使用步进电机送料,氮气弹簧压料和顶料,使模具设计难度大为降低;使用了两种楔紧块驱动型侧滑块机构对制件进行工艺面切除加工和精整形,及燕尾槽压块驱动上模侧冲孔滑块机构使制件的侧面加工得到了可靠保证。使用UG设计软件设计了模具的3D结构,较之于2D排位设计方法,更能有效避免设计缺陷,模具设计效率和可靠性更高。

汽车高强钢坐垫边梁侧件翻孔工艺优化

分析了汽车坐垫边梁侧件相应区域与衬套铆接配合的技术要求,还介绍了常规侧件连接处的生产工艺和特点,指出目前存在的问题和缺陷。通过结合材料流动规律和体积不变定律,优化并整合新工序,有效解决了边梁侧件连接处侧壁过薄、配合稳定性差的问题。结合实际生产,证明了整体工序设计合理,有效控制了成本,满足了客户的使用要求。

游动芯头拉拔孔型参数对AZ31镁合金管材成形性的影响研究

为了探索AZ31镁合金薄壁管游动芯头拉拔成形与传统工艺之间的差异,使用ABAQUS软件对其进行了游动芯头拉拔过程的模拟,并比较研究了模具与芯头锥角配合、定径带长度对拉拔管材成形性的影响。研究结果表明:在拉拔AZ31镁合金管材时,选择合适的模具角度不仅可以降低残余应力,还可以提高尺寸精度;同时,模具定径段长度对管材变形均匀性和残余应力产生较大影响。

深拉伸模气冷系统技术的开发运用

汽车行业中冷冲压深度拉伸模,无论是高于行业标准拉伸深度200mm的二次拉伸模,还是普通的深度拉伸模冲压成形时,都有走料严重发热现象。且深度拉伸模工作时走料深度深,摩擦大,冲压件受到的应力大。摩擦发热不仅仅影响冲压件板材性能,同样影响模具的材质性能,会减少模具的使用寿命并且不可预料的造成冲压件拉毛、缩颈、开裂、起皱等质量缺陷,在模具生产冲压件中后期尤为明显。故开发运用了冲压深度拉伸模气冷系统,最终解决了深度拉伸的冲压件质量问题,延长了模具和设备的使用寿命。

笔记本电脑外壳拉伸模设计

笔记本电脑外壳作为电脑外部保护装置,应有良好的电磁屏蔽特性,同时又要有一定的强度硬度,还要有较光滑、美观的外表面;笔记本电脑外壳作为浅盒型件,拉伸成形时极易起趋,甚至拉裂;在详细分析笔记本电脑外壳的结构特点后,使用UG进行三维建模,采用Autoform对拉伸过程进行有限元分析,为笔记本电脑外壳冲压选取适当的参数;本拉伸模结构合理,使用便利,冲压出的制件完全符合产品的使用要求。

胶管钢丝湿拉工艺管控要点

湿拉是钢丝在湿的状态下进行拉拔,是橡胶软管增强用钢丝最后一道生产工序。钢丝湿拉工序为多机台集中式规模化生产,人均看机量大,但是单机台生产工艺雷同,需凝练出重要的工艺点即可进行很好的管控。在实际生产中,拉丝设备的维护状态、润滑液的组分指标、拉丝模具的选用等方面直接关系着钢丝品质的优劣,对这几项重要工艺点必须进行重点管控。使用自动化手段辅助生产,能极大地提高钢丝产品的质量和产能。

汽车前车门加强板冲压工艺设计及成形优化

针对汽车前车门加强板变形复杂、材料流动不易控制、成形开裂等问题,首先分析了汽车前车门加强板结构特点,确定了“一模两件”的总体成形方案,并详细设计了拉延成形、修边-冲孔-整形、修边-侧冲和侧修边-侧冲孔-冲孔-切断的成形过程。其次以材料减薄率为切入点,采用数值模拟探究了压边力、模具间隙和冲压速率对零件成形质量的影响规律,预测了零件开裂的位置和程度,得到了较为优异的工艺参数:压边力控制在400 kN以内,模具间隙不小于1.10 mm,冲压速率不高于3000 mm·s^(-1)。最后采用正交试验方法,得到了各因素各水平最大减薄率平均值,计算出压边力、模具间隙和冲压速率这三者的极差分别为3.223%、1.489%和0.763%。基于分析结果得到了压边力300 kN,模具间隙1.15 mm,冲压速率3000 mm·s^(-1)的最优工艺参数组合,并进行了生产试验验证,制出了合格成形零件实物。