基于蚁群算法的纯铜粉末注射成形工艺参数选择方法

提出一种适用于金属粉末注射成形工艺参数优化的蚁群算法模型,给出一种参数优化实际数学模型,并以纯铜粉末注射成形参数优化问题为例进行了验证.与正交试验结果相对比,蚁群算法在工艺参数的选取上具有较高的效率和准确性.该研究可以为蚁群算法应用于过程复杂、影响因素多的金属粉末注射成形工艺参数优化提供参考.     

轧制差厚板纵向弯曲回弹分析与预测

将轧制差厚板应用于梁类零件的制造能够实现汽车轻量化，但同时也带来了更为复杂的回弹问题。为了掌握差厚板梁类零件的回弹机理并获取各种工艺参数对回弹的影响规律，通过仿真与试验手段研究差厚板U型件纵向弯曲回弹问题。首先，建立差厚板U型件纵向弯曲成形与回弹有限元模型，完成成形与回弹过程仿真，并通过冲压试验对仿真结果进行验证，讨论差厚板回弹分布情况及其原因，分析退火工艺对差厚板回弹的影响规律及内在机理。接着，基于差厚板U型件回弹仿真结果，进行正交试验设计，在此基础上完成回弹影响因素的灰色关联分析，获取各因素的影响水平以及优化的参数组合。最后，完成BP神经网络模型的构建，实现差厚板U型件的回弹预测。研究结果表明，双斜率退火工艺能够减小差厚板的回弹，并且使得回弹分布更加均匀。灰色关联分析获取的最优工艺参数组合为过渡区位置-20 mm、过渡区长度50 mm、板料厚度1.6/2.0 mm、板料尺寸80 mm×230 mm,采用最优工艺参数组合成形的差厚板U型件可以获取更低水平的回弹量。不同工艺参数对差厚板U型件弯曲回弹的影响程度按降序排列为板料尺寸、过渡区位置、过渡区长度、板料厚度。建立的神经网络模型具有...     

喷射成形7055铝合金搅拌摩擦焊的焊缝组织与力学性能

采用全自动控制的往复喷射成形工艺批量生产大规格的7055铝合金锭坯,对喷射成形7055铝合金板材进行搅拌摩擦焊.通过对搅拌摩擦焊塑性连接时的焊缝成形、焊缝组织及力学性能进行研究,实验结果证实:用搅拌摩擦焊焊接4mm厚的7055铝合金板材,选用合适的工艺参数,可获得外形美观、组织无缺陷、无变形的焊缝.焊缝各区域的组织有明...     

喷射成形制备Al-Zn-Mg-Cu系高强高韧铝合金的研究

采用喷射成形技术制备了Al Zn Mg Cu系高强高韧铝合金 ,对喷射成形工艺参数进行了优化 ,对沉积坯件的热挤压工艺、热处理工艺进行了探索 ,对材料的组织进行了分析并对不同状态的材料性能进行了比较。结果表明 :当喷射成形工艺参数合理时 ,沉积坯件具有良好的成形性与致密度 ,在随后的热挤压过程中 ,通过较低的挤压比即可使材料达到全致密 ;沉积坯件热挤压温度的降低有利于使材料获得更高的力学性能 ;同时 ,通过对合金热处理的优化 ,可以获得加工和使用性能更加优良的Al Zn Mg Cu系高强高韧铝合金材料     

电磁成形中成形效率的探讨

电磁成形是一种快速、高效的塑性成形方法。本文研究了影响电磁成形的诸因素，主要是电容和电感，分析其参数对成形的影响，从而得到比较优化的技术工艺达到了提高成形效率的目的。     

铝合金薄壁矩形管绕弯成形起皱极限的预测

失稳起皱是铝合金薄壁矩形波导管绕弯成形过程中的主要缺陷之一,严重制约着薄壁矩形管绕弯成形极限的提高.笔者采用有限元数值模拟结合正交回归分析的方法,建立了薄壁矩形管绕弯成形起皱波纹度回归预测模型,并通过实验验证了该模型的可靠性;在此基础上推导出了基于失稳起皱成形极限的解析模型.研究获得了芯头个数、防皱块与管坯间隙及芯模与管坯间隙对起皱极限的影响规律,并获得了铝合金薄壁矩形管绕弯成形起皱极限图.该研究为提高实际生产中薄壁矩形管绕弯成形质量提供了依据和指导.     

TC2钛合金管材挤压工艺

TC2是一种a＋β型钛合金，化学成分为Ti-4Al-1.5Mn，属于中强钛合金，具有良好的可焊性，主要用作连接管路。该合金变形能力较差，压力加工成形较困难。在我国，该牌号钛合金的熔炼、锻造、棒材和板材加工技术已趋成熟，但管材加工仍属空白。针对该合金的特点，采用挤压后机加工的方法生产热加工管材。重点对化学成分、挤压温度、挤压比、退火温度对管材挤压成形、组织性能等的影响进行了研究，确定了合理的工艺参数，研制的管材表面质量、组织性能及尺寸精度完全满足相关标准要求。     

非规则管坯喷射沉积成形工艺优化及试验验证

提出了基于往复式喷射成形工艺制备大璧厚非规则管坯的近终形成形工艺及其工艺参数优化方法,以实现坯件从CAD设计到喷射成形的快速制备过程。该工艺方法包括三个阶段:非规则管坯的三维CAD设计、分层处理和单层沉积厚度计算;基于沉积厚度与往复速度和质量流率的对应关系,计算满足各层沉积厚度所对应的控制参数;利用控制系统和执行机构对控制参数进行实时控制和调节,采用往复式多层喷射成形工艺制备满足设计轮廓的管坯。通过试验进行了验证,喷射成形制备的管坯形状和轮廓与CAD设计模型较好地一致,表明了该工艺方法的可行和正确性。     

CT20钛合金薄壁管材数控冷弯成形行为研究

薄壁管材的小弯曲半径数控弯曲成形十分困难,外侧壁厚减薄是弯管成形中的加工缺陷之一,对于钛合金薄壁管尤为严重。采用模拟与实验相结合的方法,对规格为58 mm×1.5 mm的CT20钛合金管材数控弯曲成形过程中弯曲段的壁厚减薄进行了研究,得到相对弯曲半径对壁厚减薄的影响规律。结果表明,CT20钛合金管材冷弯成形时的极限相对弯曲半径(R/D)为2。     

DP590/DP780高强钢管液压成形的性能

为对生产进行指导,研究了DP590/DP780高强钢焊管在液压成形过程中的变形行为;使用场发射扫描电镜观察管材周向的横截面以确定基体的组织,通过VMHT30M显微硬度计确定管材的焊缝及热影响区的大小,以便研究液压成形破裂行为;采用液压成形试验机对两种管件进行液压成形研究。实验结果表明:管材在胀形过程中的破裂压力比理论计算公式得到的破裂压力大,破裂位置全部位于靠近焊缝及热影响区的母材区域;随着管径的增大和长径比的增大,管材的极限膨胀率呈现下降趋势;在自由胀形过程中,管材的焊缝区域基本上不发生减薄,最小壁厚位于管材的热影响区和基体的过渡区域,并且壁厚的减薄率在胀形最高点所在截面最大,越靠近管材夹持区,壁厚的减薄率越小。最终得到以下结论:管材液压成形实验是准确获得管材力学性能参数的途径;提高焊接质量有助于控制失效破裂位置;合理选择管材的长径比有利于管材性能的充分发挥;通过合理控制各处的减薄有利于降低液压成形件的破裂风险。      

Stretch Bending of Z-section Stainless Steel Profile

The stretch bending properties of a new Z-section stainless steel profile were investigated by simulation.The causes of the forming defects,such as section distortions and poor contour precision,were analyzed,and the corresponding controlling methods were proposed.The results show that the main forming defects for the stretch bending of the Z-section profile were the flange sagging,the sidewall obliquing inward,the bottom surface upwarping,and the bad contour accuracy;the cross-section distortions were mainly induced by the shrinkage of the sidewall,which could be eliminated by increasing the sidewall height of the profile reasonably;the poor contour precision was mainly due to springback,which could be controlled by modifying the die surface based on the springback amount;for the investigated bending beam,the proper sidewall height compensation was 2mm,and the suitable die surface modification amount was 1.2times of the springback amount,when the elongation was 10% of the initial profile length.Stretch bending tests were conducted on a new type of die with adjustable bending surfaces,and high quality components were achieved,which verified the effectiveness of the defect controlling measures.     

大口径薄壁白铜管无外模扩径拉拔数值模拟

采用Deform-3D软件模拟Φ273 mm×16 mm生产Φ330 mm×11 mm大口径薄壁白铜管的无外模扩径拉拔过程, 分析了扩径过程中管材周向应力的演变规律及管材尺寸的变化规律。结果表明: 在无外模扩径拉拔过程中, 扩径部分管材的周向应力由外表面的拉应力过渡到内表面的压应力, 回弹部分管材的周向应力由外表面的压应力过渡到内表面的拉应力, 且管材内外表面的周向应力分布随管材口径的增大及壁厚的减小而更为集中。经无外模扩径拉拔后的管材存在回弹现象; 采用考虑了管材原始壁厚和扩径量的关联模型S=16.0986+0.9256×S₀-14.8743×D/d(mm)可较好地预测扩径后管材的壁厚。      

A Model for Predicting the Yield Strength Difference between Pipe and Plate of Low-Carbon Microalloyed Steel

A combination of finite-element calculation and tension-compression tests was employed to predict the yield strength difference between the pipe and plate of low-carbon microalloyed steel (LCMS) in the production of high-frequency straight bead welding pipes (HFSBWPs). The deformation process was divided into bending, flattening, and tension deformations. The bending and flattening deformations were simulated using a finite-element method in order to obtain circumferential strains at pipe wall positions along the wall thickness. These strains were the transition strains in the subsequent tension-compression-tension and compression-tension tests. The yield stresses (0.5?pct proof stresses) at the pipe wall positions were derived from the obtained stress?Cstrain curves. The average of the obtained yield stresses was taken as the predicted yield strength of the pipes. It is found that the difference between the latter and the strength of the original steel plates is a result of the combined action of the Bauschinger effect and strain hardening caused by bending and reverse bending deformations. It is strongly dependent on the ratio of pipe wall thickness to pipe outer diameter (T/D ratio). At low T/D ratios, the Bauschinger effect was dominant, resulting in a decreased yield strength. Strain hardening due to work hardening was dominant at higher T/D ratios, resulting in an increased yield strength. The increase in yield strength was greater at the inner pipe walls than at outer ones, indicating that strain hardening is stronger at inner pipe walls. The yield strength differences predicted with the presented approach are comparable with the values obtained from industrial productions of HFSBWPs, indicating that this approach can be used to predict the yield strength difference between pipe and plate of LCMS.     

轿车A柱连接件级进模设计

首先,针对轿车A柱连接件,进行了制件的冲压成形工艺分析,设计出8工位排样设计图。然后,依据排样设计图,分析了设计的要点并进行了对应的模具结构设计。模具结构设计过程中,主要通过对冲压质量、工艺要求及生产效率等因素的考虑,选择了合理的标准级进模总体结构类型,设计了一套能够完成8工序的轿车A柱连接件的模具。最后,模具组装和调试后进行了实冲试验,所冲制件符合检测要求,模具投产后可以适应冲床冲压频率要求及批量生产的要求。     

FEM Simulation of Large Diameter Pipe Bending Using Local Heating

 With the aid of elastic plastic large deformation finite element method (FEM), an elastic plastic and coupling thermo mechanical model was built to calculate the bending process of the bent pipe, combining with local heating or cooling of the bent pipe. Based on the FEM simulation, the metal deformation during the bending process was analyzed in detail. The thinning and thickening ratio of the pipe wall thickness, the ovality of the cross section of the pipe and the spring back angle, etc, are presented.     

Stretch Bending of Aluminum Extrusions: Effect of Geometry and Alloy

An experimental stretch bending study is presented in this paper. A total of 24 tests on 2-m-long rectangular hollow section aluminum specimens are performed in a specially designed stretch bending rig. All tests are carried out with a constant tensile force corresponding to the material's yield stress. Factorial analysis is systematically used in the planning of the experimental program as well as in the result interpretation. Special attention is paid to the influence of the alloy, die radius, and specimen wall thickness on certain response parameters. As stretch bending is an important industrial forming process, die force, sagging, and springback are considered to be the most relevant responses. The tests show that the alloy has the largest influence on the die force and springback, while the sagging behavior is primarily controlled by the geometric parameters (i.e., die radius and thickness).     

Edge geometry of pipe blanks produced by JCOE flexure

For the shaping of welded straight-seam large-diameter pipe in the TESA 1420 production line, methods are proposed for calculating the geometric parameters of the edge of the blank and the profile of the deforming tool. The edge geometry obtained on an edge-bending press is compared when using surface tools of involute and single-radius type. For tools of single-radius type, edge geometry consistent with the required shaping quality may be produced. For the edge-bending presses, a method of calculating the edge geometry in loading and unloading is outlined. The height of the bent edge, the residual radii of curvature, and the coordinates of the loading and unloading points at the external and internal edge contour of the pipe blank are determined. The coordinates of the edge formed by a tool with an involute profile are also calculated. The involute tool profile is universal on passing from one type of tool to another within a standardized group. The calculation permit conversion from an involute edge profile to a multiradial profile, followed by determination of the fixed coordinates of the points of the blank after springback. On the basis of those coordinates, the output edge geometry is estimated. Within the 1220–1420 mm standardized group, the longitudinal edge deformation for the 1220 × 10 mm type is calculated. Standardization is found to be much simpler with a single- radius tool profile. For edge-bending presses, a method of calculating the edge parameters of the pipe blank when using a tool with an involute contact profile is developed and tested in industrial conditions. Single- radius calibration of the profile of the edge-bending tool is proposed, such that fixed time coordinates are ensured. These are analogous to the coordinates with an involute punch profile. The blank’s weighted mean radius of curvature maximizes the agreement of the coordinates of the blank profile at fixed points in both approaches. (The maximum discrepancy is no more than 6–7%.)     

铝合金管材晶粒度的细化研究

通过控制6063管材截面晶粒尺寸,来满足某高端汽车客户标准中100μm的晶粒尺寸要求;从铸棒的均质制度、模具设计方式、挤压工艺三个方面进行优化控制,通过高倍显微镜、电导率和布氏硬度等检测方法进行深入分析。结果表明,铸棒采用高温短时的均质制度,模具减少前室的设计方法,挤压工艺使用低温快速的挤压方式,成功生产出符合高端汽车客户标准要求的管材。     

Self-propagating high-temperature synthesis metallurgy of pipes with wear-resistant protective coating with the use of industrial wastes of metallurgy production

The possibility of utilizing the industrial wastes of the metallurgical production and secondary raw materials (aluminum) by organizing self-propagating high-temperature synthesis (SHS) and obtaining metal pipes with an inner ceramic coating is investigated. The main production operations of the preliminary preparation of the starting raw materials are worked out and functional coatings providing high abrasive resistance are revealed. The results of testing the samples showed that the durability of the pipes with the deposited coating increases by a factor of more than 20. The possibility of forming highly energy-effective SHS technology of processing the industrial wastes of metallurgical production and obtaining pipes with a high abrasive resistance is shown.     

焊管方型化的连续成型工艺开发研制

在圆管直缝焊接成形基础上,应用金属变形协调关系,建立圆管方型化的连续变形生产工艺。开发连续成型的孔型系列,建立圆管方型化的塑性变形数学模型;利用有限元对各道次变形关系进行模拟,优化并确定孔型和成形工艺参数,对带材边缘的应力应变进行失稳分析;开发研制方管连续生产机组。针对方管78 mm×78 mm×3.0 mm进行试生产,获得满意结果。经理论与试验比较分析,其结果具有较好一致性,为生产实践奠定了基础。