一种空间异形三通半管成形工艺改进北大核心CSCD

为解决一种空间异形三通半管零件在传统冲压成形过程中的成形失效、表面质量不佳及成形效率低等问题,根据零件特征,结合AutoForm有限元仿真软件,对该零件的传统冲压成形过程进行了数值模拟并优化,通过分析其成形失效原因,提出了采用充液拉深成形工艺代替传统冲压成形工艺,并对该零件的充液拉深成形过程进行数值模拟并优化。通过对两种工艺成形效果的对比,验证了工艺改进的可行性。最后,在800 t双动充液成形液压机上,分别采用两种成形工艺试制零件,验证了数值模拟的可靠性和实际的工艺改进效果。通过成形工艺的改进,有效地解决了成形失效问题,表面质量和成形效率得到了显著提升,零件成形效果满足工艺需求。     

插针焊线槽成形工艺优化及模具设计改进

针对某插针焊线槽成形后存在的偏心、翘头等问题,通过成形工艺、模具设计两方面进行了原因分析,介绍了优化、改进后的焊线槽成形工艺及模具设计.     

特大型管板锻造工艺技术研究

φ6960 mm特大管板直径大、高度低、吨位重,生产操作和锻造难度极大。通过改进锻造工艺及成形方法,合理控制旋转锻压工艺参数,较好地解决了成形中遇到的难题。结合工艺性分析,建立了有限元分析模型,重点预测了成形效果和质量。并通过工业化生产试制,验证了工艺参数及成形工艺的合理性。     

割草机手把座冲压成形工艺设计

对手把座产品冲压成形工艺进行了详细的技术分析,指出了产品凸台成形难点所在,通过正确的产品工艺设计和模具设计及工艺改进,解决了产品成形中的质量问题,达到了产品技术要求,采用ST12板料已正常批量生产.     

连轴体成形工艺模拟分析

根据连轴体件凸缘较宽、凸台较高且直径较小、壁厚不均匀等结构特点及成形难点,制定了拉深和挤压2种工艺方案。采用有限元数值模拟,对2种成形工艺的模拟结果分析表明：采用拉深工艺时,成形力小,成形质量差;采用挤压工艺时,成形力大,成形质量好。通过对挤压工艺坯料形状的改进,降低了成形载荷并提高成形质量。     

空气罐封头的压形模具设计

零件的局部成形在实际生产中应用较多，在零件的形状与材料确定时，其成形质量主要取决于成形工艺和模具结构。当零件的成形工艺性较差时，就要通过改进工艺和模具结构的方法来保证零件质量。本文介绍了空气罐封头压形工艺与模具结构的改进工艺，改进后的模具改善了成形缺陷，保证了零件质量。     

插针焊线槽成形工艺优化及模具设计改进

通过成形工艺、模具设计两方面的影响因素,分析了某插针焊线槽成形后产生偏心、翘头的原因。提出了合并工序及采用弹性、浮动压紧等改进措施,并介绍了优化后的焊线槽成形工艺及模具设计。实现了插针焊线槽较高的成形质量,减轻了劳动强度,提高了工作效率。     

包角件成形工艺的改进及模具设计

通过对包角件工艺的正确分析 ,改进了原工艺方案 ,采用半厚对称成形工艺 ,简化了模具结构 ,有利于成形。改进后的模具制造、维修方便 ,降低了成本 ,提高了经济效益。     

带枝桠筒形件挤压成形工艺研究

为了获得综合性能优良的某铝合金带枝桠筒形挤压件,结合其形状特点,首先提出了一次整体挤压成形工艺方案。通过有限元模拟对成形工艺方案进行验证,结合一次整体成形中所产生缺陷进行工艺改进。并提出两种改进方案,通过有限元模拟验证,方案1为下料热处理预成形热处理终成形(冲盂成形)机械加工,获得的挤压件金属填充不饱满;方案2为下料热处理反挤压成形热处理终成形(翻边成形)机械加工,获得了合格的挤压件。对方案2的载荷位移曲线变化规律及曲线上特殊节点产生原因进行了分析,初步确定了方案2的可行性;对方案2进行模具设计并进行工艺试验。试验结果表明,采用方案2的挤压成形工艺最终得到了填充效果良好、符合生产要求的带枝桠筒形挤压件。     

衔铁成形工艺与级进模设计

通过对衔铁结构及其工艺进行分析，并通过生产实践验证和总结，分析原排样方案存在的问题及产生问题的原因，改进设计了新的成形工艺及排样方案，还介绍了主要工位的模具结构，并说明了模具设计时的注意事项。实践表明，改进后的成形工艺及排样方案能满足衔铁图纸尺寸及技术要求，模具在使用过程中稳定性良好。     

弹性导电片的冲压工艺分析和模具设计

在对弹性导电片切口、冲孔、成形、冲裁和压弯等成形工艺分析的基础上,提出了该零件采用多工位级进模的冲压方案,并介绍了该零件的冲压成形工步和模具结构。实践表明,该模具结构灵活、可靠,并能保证产品质量,提高了生产率,降低了成本。     

多道次拉深复合成形工艺研究

以典型深拉深件滤清器罩壳为研究对象，对其原有成形工艺方案进行分析，提出采用多道次拉深挤切复合成形的工艺方案，设计出了集落料、拉深、修边、整形于一体的复合成形模具。提高了生产效率和生产安全性，降低了生产成本。     

Energy dissipation in laser-based free form heading: a numerical approach

Cold forming generally allows the fast generation of parts with very low tolerances. In addition, mechanical properties are improved, if work hardening materials are used. Transferring the cold forming process to micro range leads to a decrease in the maximum achievable upset ratio so that the forming process becomes inefficient. Therefore, a laser-based free form heading process has been developed to generate preforms which can be calibrated in a secondary cold forming step. The achievable upset ratios reach values of several hundreds instead of 2.1 which is common for single step mechanical upsetting. In this article, heat losses arising in the material accumulation process using laser-based free form heading are analyzed and discussed. For this purpose, the process is modeled within the framework of continuum mechanics and simulated by a finite element method. By using a numerical approach, a systematic study on heat losses is performed in order to identify the influence of radiation, heat transfer due to convection and thermal conduction during laser irradiation time. The simulation results, which are validated with experimental data, show that the radiation is the most important mechanism reducing the efficiency of the accumulation process.     

A Combined Radial Forging-Forward Extrusion Forming Process of Alternator Poles

A combined radial forging-forward extrusion forming process of alternator poles is proposed based on an analysis of the structure of alternator poles as well as the forming die sets. First, a thick-bottom base of the alternator poles is obtained through radial forging. The middle boss and claw teeth are then formed through forward extrusion. A 3D coupled thermomechanical finite element model is employed. Billet deformation, metal flow, and forming load are obtained. The results show that the middle boss cavity is filled earlier and the process is no longer simultaneous extrusion during the second forming step. Then, the forming load increases sharply. An improved process that controls the metal flow in the middle boss cavity and aids in pushing the metal into the corners of the claw teeth cavity is proposed. The middle boss and claw teeth cavities can be filled simultaneously. The sharp increase of the forming load in the final forming stage is avoided. Simulative and experimental results show that the improved process can considerably reduce the final forming load to form a well-shaped product.     

铝合金杯类零件双面及侧面成形工艺研究

对于2A12铝合金阶梯形杯形件的塑性成形,传统工艺是由每一级的台阶单工序成形,积累为最终的多阶梯成形,由于多次加热、多套模具、多道次挤压、多道次定位放置的误差积累会造成尺寸精度低、能耗高、效率低、模具导柱和导套不耐高温的缺陷。对于杯形件的侧壁直肋与台阶外形,用传统工艺挤压内、外圆角(小于R0.5mm时)很难完成。通过有限元模拟和工艺优化,本文采用凹模内不脱模连续挤压、控制流向顺序的方法,以及采用十字键模口导向结构,形成了一次加热、一次放置毛坯成形多台阶、小圆角的新工艺。该工艺缩短了工时,提高了产品性能和材料利用率,为小圆角多台阶类型的零件实现短流程的挤压工艺转化提供了参考依据。     

不锈钢管接头成形过程的有限元模拟与实验研究

根据不锈钢管接头的形状结构特点和材料成形性能，确定该零件可采用正挤压——镦粗二次成形和一次正挤压成形两种工艺进行加工。运用有限元软件Deform-3D对确定的成形工艺过程进行模拟分析，得到金属变形和载荷变化等规律，通过工艺实验，验证模拟分析结果。结果表明：采用正挤压——镦粗二次成形时工艺力较小、变形均匀性好，采用一次正挤压成形工艺力大。     

深杯形件冷挤压工艺分析及变薄拉深模具设计

以典型冷挤压深杯形件为例,通过对零件的形状及材料的性能分析计算后确定出最佳的工艺方案,给出了各成形工序图及润滑与软化处理规范,并对其中的变薄拉深工序进行了模具设计.在设计中,首先通过工艺力计算,选用了合适的成形设备,并根据工艺特点和成形设备特性,选择和设计了变薄拉深模具的主要零件,最后给出了变薄拉深模具的总装图.实践证明,所给出的成形工艺及设计的模具能够实现深杯形件的冷挤压成形,所成形的工件尺寸精度高、强度性能好.     

Forming of bioabsorbable clips using magnesium alloy strips with enhanced characteristics

The paper shows the feasibility of manufacturing surgical clips using bioabsorbable AZ31B magnesium alloy strips characterized by enhanced forming characteristics, and, at the same time, improved corrosion resistance to human fluids that make them suitable for temporary applications. The novel process chain used for the clip manufacturing includes an extrusion-cutting step, to fabricate strips with a peculiar shear texture and extremely refined microstructure, and a dedicated bending operation to achieve the clip final shape. The strip forming operation setup was numerically designed by a multi-level finite element approach to provide the clip required shape without fracture occurrence.     

Development of multistage sheet metal forming analysis method

The multistep sheet metal forming process for axisymmetric shapes has been modeled employing a simplified finite element analysis method. The analysis is based on the idea of dividing the deformation history into several steps while applying the total strain theory of plasticity in each step. An algorithm has been developed which satisfies the potential energy minimization process at the entire nodal point grouping in each step of the forming process. Although numerical solutions have been obtained up to a four-step process, there are no inherent limitations in the basic methodology to extend it to any number of steps. The assumption of proportional loading in each step of forming was carefully examined by comparing the computed principal strain ratios with those of experimentally observed values. It was found that some regions of the sheet material undergo nonproportional straining; consequently, a single-step approximation for a multistage forming process may not give a valid result. Sensitivity of the new model to the number of intermediate steps has also been examined. It is concluded that the new model is a good approximation of the multistage sheet forming process.     

接线头冲压工艺及模具设计

通过对接线头零件的工艺分析,介绍了该复杂弯曲件的成形工艺及冲裁模设计中薄料冲裁的特点。根据料薄及硬铍青铜回弹大特点,强调设计一次成形模及二次成形模应注意的要点。生产实践证明,镶块式凸凹模结构紧凑使模具加工简单,易于安装、调试和维护。