共查询到18条相似文献,搜索用时 123 毫秒
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高精度管材拉拔过程计算机模拟研究 总被引:6,自引:0,他引:6
开发了一种适用于生产高精度管材的新型芯棒形式,利用MSC.MARC/AUTOFORGE有限元仿真软件,模拟了高精度管材的拉拔过程,分析了变形区金属变形规律、应力分布状况及拉拔力变化规律及芯棒形式与模具尺寸参数对高精度管材尺寸精度的影响规律,得出了合理的模具参数,为科研和生产提供有效的帮助。 相似文献
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高精度管材是一种内表面质量要求很高,内径尺寸允许偏差很小的管材。研究了高精度管材拉拔模具形式对管材生产的影响。开发了一种新型芯棒,利用MSC.MARC有限元仿真软件,模拟高精度管材的拉拔过程,分析了新型芯棒对高精度管材尺寸精度的影响规律,为研究和生产提供有效的帮助。 相似文献
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管材无芯棒拉拔时,直径减小的同时壁厚也会发生改变,其增厚值可达13.2%,甚至更大。但现有文献对无芯棒拉拔过程进行应力应变分析时,通常忽略壁厚的变化,这对预测管件壁厚,从而对工艺参数进行控制不利。该文不同于以往壁厚不变的假设,而是采用应力应变方程统一求解的方法,按增量理论给出壁厚变化的理论解以及应力分布。同时,选取不同的初始直径管坯进行无芯棒拉拔实验,分析变形后出口端壁厚变化规律,并与理论计算结果进行比较。结果表明,随拉拔道次变形量的不断增大,出口端管材的壁厚变化率先增大后减小,但是最终的变形总是增厚,实验结果与理论计算值吻合较好。 相似文献
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NiTi基记忆合金管材在紧固件、连接件和医疗等领域都有广泛的用涂.NiTi基记忆合金无缝管材是一种难加工型材.采用多道次冷轧加中间真空退火工艺生产成本较高.通过热加工工艺生产NiTi基记忆合金管材国际上只有少数几个国家技术过关.为深入研究其变形规律,在我国实现产业化,借助有限元模拟设计了模具、工装和拔制工艺.通过套拉开坯或机械加工管坯和金属芯棒,采用石墨润滑,在60T万能拉压实验机上对碳钢和NiTi形状记忆合金两对组合体进行400~700℃不同温度、10~15%不同到次延伸率、芯棒与管坯间不同间隙和不同长度下的温拔试验.然后加热塑性拉伸金属芯棒,使其减径并从管中取出,芯棒材料与管坯为同一种材料.温拔由一步完成或两步或多步完成,每步温拔之间不做任何处理,每步温拔芯棒要充分地改变,然后进一步延伸.成功地拔制出了表面和内部质量良好的科4mm管材.结果表明该工艺可用于NiTi基记忆合金材加工,也可供成型其他难加工管材参考.为与套拉后制件的组织性能对比研究提供素材,套拉前对管坯组织性能进行了分析. 相似文献
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管材内高压成形新加载方式的研究 总被引:1,自引:0,他引:1
介绍了管材内高压成形过程中,一种新的内压加载方式--脉冲型加载方式.并通过建立相应的有限元模型,进行了内压脉冲型加载方式下管材内高压成形过程的模拟.通过对不同加载方式模拟结果的比较,分析了脉冲型加载方式对内高压成形中金属流动、变形区变形分布及局部过度减薄等方面产生的影响.模拟结果表明:脉冲型加载在管材内高压成形过程中可以使变形区的变形更加均匀,有利于抑制局部过度减薄、对抑制最后贴膜成形的圆角部位的过度减薄作用明显;脉冲型加载方式使变形更均匀的原因是减小了金属流动阻力,使金属流动更容易. 相似文献
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比较精确地确定管材在拉拔时的拉拔力,对于制定合理的拉拔工艺,充分发挥拉拔机的能力,保证拉拔机在拉拔过程中安全可靠地运行均具有重要意义。研究了在空拉、固定芯头拉拔和游动芯头拉拔三种状况下拉拔模具定径区摩擦力对拉拔力的影响,并推导出合理的拉拔力计算公式。 相似文献
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ZK60镁合金管材热挤压成形组织演变规律 总被引:1,自引:0,他引:1
采用数值模拟和试验方法研究了变形镁合金ZK60管材挤压成形组织演变规律。根据材料热模拟试验结果,得到了ZK60镁合金动态再结晶组织演变的Yada模型中的相关系数。结果表明,当挤压速度增大时,挤压管材晶粒尺寸减小,变化规律接近线性。当挤压温度增大时,挤压管材晶粒尺寸增大。挤压比增大时,晶粒尺寸减小。晶粒尺寸数值模拟结果与试验结果吻合,最大相对误差小于16%。当温度在300~360℃时,ZK60镁合金发生了完全动态再结晶,晶粒较小且组织均匀,平均晶粒尺寸是原始晶粒尺寸的38%。 相似文献
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Wu-Jiao Xu Kai-Qing Wang Ming-Ping Zou Peng-Cheng Wang 《Journal of Materials Engineering and Performance》2013,22(4):974-982
This paper focuses on improving the quality of aluminum rectangular tube in the cold drawing process. The newly developed drawing tools (i.e., the drawing die and the plug) which are considered as one of the most significant factors influencing the final forming quality are proposed. The new-type drawing die is designed with the “convex hull” shape in sizing zone corner and the plug is featured with a “boss club” structure in sizing zone. The equivalent plastic strain, drawn tube’s dimensional accuracy, contact stress distribution, and drawing load have been analyzed for the conditions under which the original tools and the new-type ones have been used, respectively, based on finite element simulations. The simulation results show clearly that the discrepancy of plastic strain in the axial cross section and the tube axial elongation are smaller when the new-type die is employed, which indicates the more uniform metal deformation and steady material flow. Besides that, the fluctuation of wall thickness is also unobvious showing the new-type die is very helpful to improve the tube dimensional accuracy. The newly developed plug can cause higher compressive plastic strain and contact stress, which are crucial to guaranteeing the high surface quality. An experiment on the cold drawing process of the aluminum rectangular tube has been performed. The comparisons of the drawn tube dimensions, e.g., height/width and wall thickness, have been made between simulation results and practical production. Meanwhile, the surface finish has also been measured. The experimental result exhibits that the drawn tube can better fulfill the requirements of the design and usage when the new-type tool is adopted. 相似文献
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在拉拔温度850℃、拉拔速度0.7mm/s、进料速度0.5mm/s的条件下,对连续柱状晶组织BFe10-1-1合金管材进行无模拉拔成形,采用X射线法测定管材的残余应力,采用TEM进行微观组织分析,探讨了残余应力产生的机理。结果表明,沿着拉拔方向,无模拉拔合金管材的变形区外表面残余应力分布呈先升高后降低的趋势;已变形区残余应力值较为均匀;各点残余应力均为压应力,最大值为135MPa。无模拉拔成形过程中,连续柱状晶组织BFe10-1-1合金管材的晶界变得曲折,晶界周围出现不同密度的位错塞积,变形区沿拉拔方向的位错密度呈先增大再减小的趋势,这一趋势是导致产生不同程度残余应力的根本原因。 相似文献
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《稀有金属(英文版)》2019,(10)
Based on the ABAQUS/explicit finite element method,the deep drawing of 6A16 alloy pre-aged and then storaged at room temperature for 1 week with various blank-holder forces(10,14,18 kN) was studied.The distribution and variation of stress and strain in deformation zones were investigated to drive the forming property and process of the alloy.Besides,the simulation result was verified combined with the deep drawing experiments.The results show that the stress and strain of the deformation zone have an incremental trend with the blank-holder force increasing while the deformation degree and grain size within a certain deformation zone have an obvious increase and an enlargement,respectively.After the deep drawing,the hardness of products also increases with the enhancement of blank-holder force.The blank-holder force of 18 kN is certified as the preferential one by the analysis of microstructure and simulation results. 相似文献
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Feng Li Yong Chao Xu Shi Hai Li Xin Long Zhang Yun Long Lu 《JOM Journal of the Minerals, Metals and Materials Society》2011,63(11):58-61
In order to discover the deformation mechanism in compression, L-shaped components of aluminum alloy are taken as specimen
to investigate the influence of metal flow and deformation behavior in the forming process. Research results show that when
the sectional shape is fixed, the range of plastic zone in the deformation body is expanded with the increase of the height
of the billet. In addition, the deformation billet has a tendency to change from convexity both inside and outside to convexity
inside outside and concavity outside inside, and the complexity degree of deformation also increases. Flow interface in the
deformation body deviates along the radial direction to the inside billet gradually. Moreover, when the height of billet is
a constant, the flow interface disappears and the metal on the deformation billet has an outflow tendency entirely. The results
agree with the numerical simulation through experiments verification. 相似文献
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L. Sadok J. Kusiak M. Pa
ko M. Rumi
ski 《Journal of Materials Processing Technology》1996,60(1-4):161-166
The FEM calculations of the drawing stress and the effective strain distributions in the tube sinking process were performed. The calculations were done for various process parameters, including different profiles of the working part of the die. Experimental investigations included tube sinking tests of the 1H18N10T steel (approx. 18 % Cr and 10 % Ni). The Vickers hardness (HV5) distributions on the tube cross sections and longitudinal sections, in the deformation zone as well as in the drawn product, were examined. The effective strain distributions were determined basing on HV5 measurements and experimentally obtained hardness curve. The results of experiments were compared with the FEM calculations. The formulated conclusions confirm the usefulness of the method based on hardness measurements in the analysis of the strain fields in drawn products. 相似文献
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The aluminium tubes with high strength and smooth outer-surface can be produced by non-mandrel drawing process. It is an effective method to study forming mechanism of drawing process by simulation, based on which the relevant dies with reasonable dimensions can be designed to ensure tube precision. The dynamic model and elasto-plastic finite element model of the forming process were established based on FEM software Deform-3D, then the simulation was performed. The expressions about drawing load were deduced, and the influence of friction coefficient on drawing load was computed by the expressions and software respectively. Based on simulation results the deformation mechanism of drawing process without plug was expounded. According to flowing speed vector graph the law of material flowing was summarized, by which the deformation regions were partitioned. Furthermore, some potential problems of drawing process such as diameter shrinking, thickness varying were forecast and analyzed quantificationally. 相似文献