钛合金铣削参数多目标优化及神经网络预测模型建立

为有效降低钛合金TC4铣削过程中的刀具磨损及能耗的同时提升效率,以合力弯矩、加工能耗、加工效率为优化目标开展多目标优化研究。通过单因素试验分析切削参数影响规律,通过响应曲面试验建立径向基神经网络预测模型。最后将预测模型整体引入粒子群算法中进行帕累托前沿求解得到若干组合理的切削参数组合。试验结果表明：神经网络预测模型的预测精度达95%以上;多目标优化模型的优化结果可使钛合金铣削加工过程中的合力弯矩减小28.98%、加工效率提高25.93%、加工能耗减少13.08%,可为钛合金铣削加工切削参数的选择及多个生产目标之间的协调提供有力支持。     

NSGA-II与MOPSO算法的多工序车削节能优化比较分析

在实际加工约束条件下,建立以表面粗糙度和能量消耗为目标的多工序车削优化模型的切削参数优化选择十分必要。运用NSGA-II算法和MOPSO算法对多工序车削模型进行优化比较。优化实例表明:NSGA-II算法能够获得了比MOPSO算法更优的表面粗糙度、能量消耗的Pareto最优解集以及相应的粗、精切削参数,为多工序车削参数优化选择提供了依据。     

花岗石锯切过程中的比能变化特征

金刚石圆盘锯已成为目前切割花岗石的最主要工具，对锯切过程进行深入地研究对于降低加工成本和提高加工效率有着非常重要的意义，能量消耗对所有加工过程都起着重要的作用，本文着重围绕在不同的加工参数下锯切花岗石时主轴电机消耗功率的变化情况，并结合比能u与单颗金刚石磨粒最大切削厚度hmax的对应关系对花岗石锯切过程中的能量特征进行量化研究。     

数控机床能耗单元能耗成分分析数学模型

针对数控机床能耗源众多的特性,从能量消耗的去向出发对其能耗成分数学模型进行研究。分析数控机床各能耗单元的能耗构成,将数控机床能耗划分为加工能耗和辅助能耗,其中辅助能耗又可以细化为间接加工能耗和损失能耗,加工能耗主要与机床载荷有关,而辅助能耗与机床负载相对独立,可以近似为一个常量。基于数控机床各能耗单元的能量平衡方程,建立能耗单元能耗成分分析数学模型,该模型可为数控机床加工过程中的能量效率分析与预测提供一种新的理论方法,同时为进一步优化机床能效奠定理论基础。     

Virtual process systems for part machining operations

This paper presents an overview of recent developments in simulating machining and grinding processes along the NC tool path in virtual environments. The evaluations of cutter–part-geometry intersection algorithms are reviewed, and are used to predict cutting forces, torque, power, and the possibility of having chatter and other machining process states along the tool path. The trajectory generation of CNC systems is included in predicting the effective feeds. The NC program is automatically optimized by respecting the physical limits of the machine tool and cutting operation. Samples of industrial turning, milling and grinding applications are presented. The paper concludes with the present and future challenges to achieving a more accurate and efficient virtual machining process simulation and optimization system.     

粗加工过程中进给速度的优化

粗加工进给速度优化是指以最高生产率为目标函数,以最大主功率等为约束条件,按照用户设定的优化参数自动调整不同加工段的进给速度来保持恒定最大主功率状态,从而使单位时间内的材料切除量最大.使用仿真、验证与优化软件VERICUT,可以自动编制带有最佳进给速度的加工程序,减少或避免人工调整进给速度产生的种种问题,大量缩短加工时间.以粗加工为例,对其优化原理进行了探索,初步建立了优化数学模型,并通过典型实例实现了优化.     

基于数值模拟的太阳能直拉硅单晶热场降耗研究

通过计算机数值模拟仿真技术分析了TDR-95A-ZJS型22英寸太阳能直拉硅单晶热场结构中影响能耗的主要因素。基于模拟结果提出了通过改变部分热场结构及保温毡布局等优化措施可有效降低原有热场功耗。实际生产实验表明,优化后的热场在保证晶体生长原有质量前提下较原有热场节能29%。     

车间能耗实时监测系统的研究与设计

为了提高车间能耗的监测与管理水平,从远程监测管理角度出发,定义具有拓展性的车间设备组网协议,设计一种车间能耗实时监测系统,以此监测管理车间实时能耗情况,为车间能量效率评估和车间设备维护、升级、改造提供准确数据支持。该系统已实际应用于数控加工车间的能耗监测,实际应用表明:该系统能实时监测车间能耗情况,数据传输实时性强、稳定性好,增强了企业对车间能耗的管控。     

The form error reduction in side wall machining using successive down and up milling

In this paper, the form error reduction method is presented in side wall machining. Cutting forces and tool deflection are calculated considering surface profile generated by the previous cutting such as roughing and semi-finishing. Using the form error prediction from tool deflection curve, the effects of tool teeth numbers, tool geometry and cutting conditions on the form error are analyzed. The characteristics and the differences of generated surface shape in up and down milling are also discussed and over-cut free condition in up milling is presented. The form error reduction method through successive down and up milling has been suggested. The effectiveness and usefulness of the suggested method are verified from a series of cutting experiments under various cutting conditions. It is confirmed that the form error prediction from tool deflection in side wall machining can be used in proper cutting condition selection and real time surface error simulation for CAD/CAM systems. This research also contributes to cutting process optimization for the improvement of form accuracy in die and mold manufacture.     

面向发动机部件定制加工的矩阵式智能产线设计

针对发动机制造企业提出的部件个性化定制加工需求,提出一种矩阵式智能产线布局,围绕产线的功能分析、方案设计、仿真与调试验证等多维度进行开发,通过整合物联网、智能控制、工业机器人、MES系统等先进技术实现智能排产、加工、检测、装配和仓储等功能;结合工艺仿真手段对所设计产线进行场地布局优化和虚拟调试,根据仿真结果搭建并成功调试产线。实践证明:产线设计合理、运行稳定,达到预期的设计要求,可实现发动机部件的全过程智能化生产。     

伺服泵控数控折弯机能耗分析

本文介绍了伺服泵控折弯机液压系统工作原理,建立泵控和阀控系统仿真模型。同时在一个工作循环内比较泵控和阀控模型的功率和油耗等,得出伺服泵控较阀控系统在减少能耗方面更有优势。     

放电能量实时控制的双极性电火花加工脉冲电源

通过观测电火花放电现象对加工的影响,发现可控的双极性电火花加工能用更低的加工刀具磨损率获得比传统单极性电火花加工更高的材料去除率和效率,因此基于先进的电力电子技术,提出了一种双极性通用型电火花加工用脉冲电源,并给出相应的能量控制策略,还采用可提供连续正负脉冲输出的全桥电路作为该脉冲电源的主电路,并引入间隙电压和间隙电流的和作为唯一的控制量,在引弧阶段采用电压控制,在放电阶段采用电流控制。用一个电路完成放电间隙的击穿和放电能量的控制,减小脉冲电源系统的体积,同时在单个放电过程的各个阶段,对脉冲电压、放电电流、放电持续时间和消电离时间等参数进行合理灵活的调整,在维持放电频率一定的情况下,保证加工过程中单次放电能量的一致,从而实现高效均匀的电火花加工。     

A study on energy efficiency improvement for machine tools

Energy consumption reduction is critical in various industrial environments. Machine tool manufacturers could contribute to this matter by developing advanced functions for machines. Power consumption of machining center was measured in various conditions. The conclusion was that modifying cutting conditions reduces energy consumption. This applies for either regular drilling, face/end milling or deep hole machining. Also, a new acceleration control method is developed to reduce energy consumption by synchronizing spindle acceleration with feed system. Experiments were performed to verify these methods and promising results were achieved.     

钛合金TC4切削过程流动应力模型研究

运用有限元技术对切削过程进行仿真可以预测切削力、切削温度、应力分布,优化刀具参数和切削条件。建立适合于切削条件中大应变、高应变率条件下材料的流动应力模型,是切削过程有限元仿真的关键技术。文章通过正交切削实验和有限元迭代的方法,修正了难加工材料TC4在大应变、高应变率条件下的J-C流动应力模型,使修正模型能够适应切削仿真中的大应变、高应变率要求。计算结果表明,采用新的J-C流动应力模型进行计算,所得主切削力值与实验测量值的平均误差从36.28%降为12.06%,进给力的平均误差由原来的61.03%降为现在的25.57%。该修正的流动应力模型比用霍普金森实验所得到的流动应力模型更适合于切削过程的有限元仿真,可以提高切削仿真的计算精度。     

齿轮成形磨削能耗与表面粗糙度研究

齿轮成形磨削的能耗研究对于高精度齿轮的低碳制造具有重要意义.从数控成形磨齿机床的部件层面出发,分析齿轮成形磨削的能耗组成部分;基于磨削功率和材料切除率,建立齿轮成形磨削的净能耗密度模型;通过齿轮成形磨削试验发现,增加磨削能耗,会使表面粗糙度减小,但随着磨削能耗的持续增加,表面粗糙度减小幅度有限.研究结果为齿轮成形磨削的能耗与加工质量协同优化控制奠定了理论基础.     

大型汽车塑件整体式热流道系统技术创新

介绍了一种属于汽车制造领域的先进制造系统,主要研究汽车塑件生产中的包括保险杆、仪表盘、侧门板、脚踏板等在内大型汽车塑件模具中关键部件热流道系统的制造工艺。本项目的热流道是整体式机构,用来解决大型塑件的成型问题,项目利用螺纹连接技术,代替传统的面贴面正压的安装模式,有效解决加热膨胀的错位及漏问题。同时一体式热流道系统,采用深孔加工技术和流体式抛光技术并配备4轴加工的发热圈凹槽内镶式加热器,保证流道光滑无死角的同时,保证了加热的均匀性和热传导的高利用率。一系列的技术应用使此热流道系统比常规热流道产品合格率提高;更节省原材料;功耗更低,同时维护保养变得更简单,使模具的维护成本更低。     

Reduced energy consumption by using streamlined gating systems

In foundries a lot of effort is done to minimize energy consumption in the production to reduce costs and hence increase the competitiveness. At the same time the foundries must live up to the increased demands for high quality castings. Traditional gating systems are known for a straight tapered down runner, a well base and 90° bends in the runner system. Previous work has shown that the traditional way of designing gating systems creates high inconsistency in flow patterns during filling. In the streamlined gating systems there are no sharp changes in direction and a large effort is done to confine and control the flow of the molten metal during mould filling. The main objective in the work presented here is to use the principles of the streamlined gating systems to reduce the weight of the gating system relative to the traditional layouts. By reducing the weight of gating system and thereby improving yield, the amount of molten iron needed is also reduced, hence reducing the energy consumption for melting. Experiments in real production lines have proven that it is possible to achieve a reduction in the poured weight by using the streamlined gating systems. In a layout for casting of three valve housings in a vertically parted mould the weight of the gating system was reduced by 1.1 kg changing from the traditional layouts to the streamlined gating systems. This weight reduction corresponds in this case to a 20% weight reduction for the gating system. Using streamlined gating systems with fan gates to give a beneficial heat distribution in the castings may be an efficient tool to eliminate the need for heat treatment. In the experiments the change in gating system from the traditional layout to the streamlined layout removed the need for heat treatment. This obviously means a huge energy saving in the foundry. The energy consumption for heat treatment of iron has been found to be 0.489 kWh/ kg. The valve housing in the experiments weighs 3 kg so when the need for heat treatment is removed, around 1.5 kWh     

Energy dissipation in modulation assisted machining

The specific energy in modulation assisted machining (MAM) – machining with superimposed low frequency (<1000 Hz) modulation in the feed direction – is estimated from direct measurements of cutting forces. Reductions of up to 70% in the energy are observed relative to that in conventional machining, when cutting ductile metals such as copper and Al 6061T6. Evidence based on chip structures and strains, stored energy of cold work, recrystallization, and finite element simulation of chip formation, is presented to show that this reduction is due to smaller strain levels in chips created by MAM. A simple geometric ratio of the length to thickness of the ‘undeformed chip’, which can be estimated a priori from MAM and machining parameters, is shown to be a predictor of the transient chip formation conditions that result in the reduction in specific energy and deformation levels.     

Resource efficiency and environmental impact of fiber reinforced plastic processing technologies

The process energy demand and the environmental indicators of two carbon fiber reinforced plastic process chains have been investigated. More precisely, the impact of different production set-ups for a standard textile preforming process using bindered non-crimp fabric (NCF) and a material efficient 2D dry-fiber-placement (DFP) process are analyzed. Both 2D preforms are activated by an infrared heating system and formed in a press. The resin-transfer-molding (RTM) technology is selected for subsequent processing. Within a defined process window, the main parameters influencing the process energy demand are identified. Varying all parameters, a reduction of 77% or an increase of 700% of the electric energy consumption compared to a reference production set-up is possible, mainly depending on part size, thickness, and curing time. For a reference production set-up, carbon fiber production dominates the environmental indicators in the product manufacturing phase with a share of around 72–80% of the total global warming potential (GWP). Thus, the reduction of production waste, energy efficient carbon fiber production, and the use of renewable energy resources are the key environmental improvement levers. For the production of small and thin parts in combination with long curing cycles, the influence of the processing technologies is more pronounced. Whereas for a reference production set-up, only 10% (NCF–RTM) and 15% (DFP–RTM) of the total GWP are caused by the processing technologies, a production set-up leading to a high process energy demand results in a share of 40% (NCF–RTM) and 49% (DFP–RTM), respectively.