Multi-objective optimization of machining parameters considering energy consumption

This paper deals with multi-objective optimization of machining parameters for energy saving. Three objectives including energy, cost, and quality are considered in the optimization model, which are affected by three variables, namely cutting depth, feed rate, and cutting speed. In the model, energy consumption of machining process consists of direct energy (including startup energy, cutting energy, and tool change energy) and embodied energy (including cutting tool energy and cutting fluid energy); machining cost contains production operation cost, cutting tool cost, and cutting fluid cost; and machining quality is represented by surface roughness. With simulation in Matlab R2011b, the multi-objective optimization problem is solved by NSGA-II algorithm. The simulation results indicate that cutting parameters optimization is beneficial for energy saving during machining, although more cost may be paid; additionally, optimization effect on the surface roughness objective is limited. Inspired by the second result, optimization model eliminating quality objective is studied further. Comparing the non-dominated front of three-objective optimization with the one of two-objective optimization, the latter is proved to have better convergence feature. The optimization model is valuable in energy quota determination of workpiece and product.     

An energy consumption prediction approach of die casting machines driven by product parameters

Die casting machines, which are the core equipment of the machinery manufacturing industry, consume great amounts of energy. The energy consumption prediction of die casting machines can support energy consumption quota, process parameter energy-saving optimization, energy-saving design, and energy efficiency evaluation; thus, it is of great significance for Industry 4.0 and green manufacturing. Nevertheless, due to the uncertainty and complexity of the energy consumption in die casting machines, there is still a lack of an approach for energy consumption prediction that can provide support for process parameter optimization and product design taking energy efficiency into consideration. To fill this gap, this paper proposes an energy consumption prediction approach for die casting machines driven by product parameters. Firstly, the system boundary of energy consumption prediction is defined, and subsequently, based on the energy consumption characteristics analysis, a theoretical energy consumption model is established. Consequently, a systematic energy consumption prediction approach for die casting machines, involving product, die, equipment, and process parameters, is proposed. Finally, the feasibility and reliability of the proposed energy consumption prediction approach are verified with the help of three die casting machines and six types of products. The results show that the prediction accuracy of production time and energy consumption reached 91.64% and 85.55%, respectively. Overall, the proposed approach can be used for the energy consumption prediction of different die casting machines with different products.     

An unconstrained approach to blank localization with allowance assurance for machining complex parts

In machining large complex parts with critical stock allowance, even small deviations in the blank parts or slight inadequacy in the fixturing may result in local shortage of material (i.e., insufficient stock allowance). This paper presents an optimal localization algorithm that aligns the measured points from a blank part with the nominal model to assure the weakest allowance area with as much material to be cut as possible. Instead of exploiting extra constraints to force the allowance at each point larger than a specific value, which is a popular strategy for allowance assurance in the previous localization algorithms, we formulate the blank localization problem as an unconstrained max-min problem. To deal with the unsmoothness exhibiting in the max-min objective function, a method based on the entropy optimization principle is adopted to convert the non-differential objective function to an unconstrained differential one, which can be efficiently solved using the conventional Quasi-Newton algorithms. The unconstrained optimization result finally gives rise to localization with the maximum allowance margin. For the blank parts that the material shortage is inevitable, the method can still efficiently achieve reasonable localization results, which confine the material shortage to a least extent. The proposed method is easy to be implemented and works well for both sparse sample points and dense-scanned points. Case studies included justify the superiority of the proposed scheme over the existing non-linear constrained optimization solutions.     

1种挖掘机恒压网络二次调节液压系统及其能耗分析

为开发高效节能型挖掘机,提高能量的利用率,分析了现有挖掘机液压系统在节能控制方面存在的不足,提出1种基于恒压网络二次调节技术的挖掘机液压系统的设计方案,分析了该方案的特点.以具体挖掘机工况为例,对3种不同的挖掘机液压控制系统进行能耗分析与对比,结果表明基于恒压网络二次调节技术的挖掘机液压控制系统是可行的,且具有较好的节能效果.     

毛坯尺寸基准的理论研究

传统毛坯尺寸基准设计忽略了工艺过程的差异,而统一将零件图中各尺寸基准作为毛坯尺寸基准,导致毛坯在后续加工过程中余量误差增大而浪费材料.以粗加工余量公差最小以及加工面与非加工面误差最小为目标,提出毛坯尺寸基准设计的新方法,对提高机械产品质量、降低材料消耗有重要意义.     

弧齿锥齿轮的轮坯设计

根据格里森制弧齿锥齿轮齿根倾斜的原理,本文论述了齿轮轮坯的设计方法和步骤,并以某轮式车辆三桥传动箱中的一对弧齿锥齿轮的实际制造为例,得出该设计方法能够满足使用要求,并在很大程度上提高了生产效率的结论.     

Dynamic rescheduling in FMS that is simultaneously considering energy consumption and schedule efficiency

The dynamic rescheduling problem in flexible manufacturing systems (FMS) has historically emphasized the schedule efficiency. However, energy consumption is a basic need for different purposes in manufacturing systems around the world. This paper proposes an innovative approach to study the dynamic scheduling problem in FMS, taking the objectives of minimum or maximum energy consumption into account. A new goal programming mathematical model, which considers the energy consumption and the schedule efficiency simultaneously, is presented for solving this problem. A rescheduling method based on the genetic algorithm is introduced to address the dynamic rescheduling problem in FMS. A period policy is selected to deal with the dynamic feature of the problem. Numerical experiments have been designed to test and evaluate the performance of the proposed model. The experimental results show that the minimum energy consumption model can save the energy consumption and enhance the schedule efficiency.     

考虑工位约束及能耗的双边拆卸线平衡问题建模与优化

针对现有双边拆卸线对能耗问题研究的不足,以最小化工作站数、负载均衡指标、危害指标和能耗指标构建了多目标双边拆卸线数学模型.该模型新增工位优先关系及站内位置两种约束,线性化表达了具有优先关系约束的拆卸任务的分配方式;明确了分配至同一工作站内不同任务间的相对位置关系.结合双边拆卸线问题特征,提出一种改进差分进化算法,该算法...     

Development of aspect dummy considering seat dimension factor

The HPM-I dummy that was used to design car seats was developed by referring to human body dimension data in the 1960s, not to reflect changes of body sizes in accordance with time flow. Also, the HPM-I dummy that was made of one plate of a back rest could not express various kinds of postures. Thereafter, HPM-II, which had three back rests, was developed, but it could not consider various kinds of seat dimension factors by body size of 50th percentile male. We developed not only a 5th percentile female model but also 95th percentile male model to make use of them for automobile seat design and rating. The study developed the HARB model, HPM-II model, and CAD model of each percentile based on 50th percentile male HPM-II dummy.     

拉深件钣坯计算机辅助设计软件开发

钣坯的形状与尺寸将直接影响到拉深过程中材料的流动以及制件的最终品质。基于与拉深件几何构形复杂度无关的通用钣坯设计方法———逆向逐层展开算法,利用VB开发了拉深件钣坯计算机辅助设计软件。从模块构成、功能描述、构形数据结构以及开放式数据库连接技术等方面对该软件进行系统介绍。     

高工效、低能耗剪叉式液压升降机设计研究

针对液压升降机的结构和工作特点及存在问题,作了改进设计。驱动缸采用垂直布置,并通过U形连接架驱动剪叉臂和工作台,连接架的侧板与内侧剪叉臂的横梁间的筋板用销轴转动连接,焊装在缸底及活塞杆端部的钢球嵌装在连接架横撑上的球窝中,构成球铰实现高约束的转动连接,保证外载荷始终作用在液压缸的纵轴线上,消除偏载;采用插装阀构成液压系统,提高液压系统可靠性、效率和抗污染能力,并解决了阀集成安装的问题,提高了液压系统的工效;用蓄能器回收及再利用势能,降低了能耗。     

多工序尺寸及公差优化

为提高产品制造质量、降低产品制造成本,提出了一种多工序尺寸及公差的优化方法.该方法综合考制造成本、质量损失和加工能力指数,以加工能力指数分别修正制造成本一公差函数和质量损失函数,在工序内建立总成本一公差函数模型.在此基础上,采用目标层解法优化特征内的各个工序基本尺寸和尺寸公差,最终达降低特征总成本的目的.最后以一个仿真实例验证了该方法的可行性.     

支持企业能效评估的能源消耗过程仿真方法

为定量和定性分析企业能源消耗情况,结合企业能源消耗过程多装置、多过程、多工序的并行、串行、返流等特性,在研究面向企业能源消耗过程的模糊扩展Petri网的基础上,深入分析了模型的有效冲突及其解决策略,提出了基于该模型的企业能源消耗过程仿真方法,并详细地给出了仿真模型和仿真算法的具体实现。实例仿真表明,该方法可以有效地模拟企业生产过程中能源使用与消耗的动态行为,为企业提供直接能耗、间接能耗等相关数据,是一种行之有效的企业能效评估方法。     

An automatic mark-up approach for structured document retrieval in engineering design

Information and knowledge retrieval has been recognized as a key issue in engineering design. A great deal of design-related information used and generated within engineering companies is formally recorded in documents. These documents become more useful if they are structured in a consistent way so that they can be retrieved and their contents accessed more effectively. Achieving useful structure in electronic documents relies on embedding some sort of mark-up or coding that is computer-understandable. Manual mark-up is time-consuming and costly. This paper proposes a knowledge engineering approach to automatic document mark-up employing XML (the eXtensible Mark-up Language) to ’tag’ explicitly the structural information. The focus here is on long and complex engineering documents. A three-level model is explored to achieve automatic semantic mark-up using a set of document decomposition schemes. The model includes a strategic level which identifies document typographical features based on such things as styles, inference or templates; a tactical level to define the rules to realize semantic mark-up according to the document features; and an operational level to perform the computational implementation of the mark-up rules. By making document structure explicit, information retrieval can be made more focused by returning not just whole documents but the document components that are most relevant or of most interest to the engineering designer, and information relevant to the designer’s need both with respect to document structure and content, not content alone. In addition, interpretation of useful structure by the human user can be hardwired into documents, which allows us to move closer to true semantic level retrieval.     

考虑不确定性的多学科设计优化分解方法

为提高不确定性情况下多学科设计优化分解的合理性,研究不确定性因素对分解目标的影响,提出了考虑不确定性的多学科设计优化分解方法.首先将布尔型函数关系矩阵扩展为"相关性一规模"两层函数关系矩阵,给出了规模矩阵元素与设计变量不确定性的定量关系.然后针对该矩阵提出了任务规模、任务平均度和任务耦合度的概念,给出了三者的计算方法.在此基础上分析确定了优化目标、约束条件、优化变量,建立了整数规划模型,并应用遗传算法进行求解.最后以齿轮减速器为例进行分解,分解结果证明了本方法的合理性与先进性.     

An object oriented approach to design with modules

The modular design of products leads to a large number of different products by creating distinct combinations of modules and components. This can give each product distinctive functionality, features, and performance levels. The design of modular products is of considerable importance in enabling companies to respond rapidly to changes in the market environment. This paper is concerned with the area of design with modules (DwM), which involves selecting the module combination to best satisfy the given set of requirements. The aim of this paper is to develop an approach for DwM, to meet customer requirements, using modules that come from suppliers that may be geographically separated and on differing computer platforms. An object-oriented approach for DwM, termed object-oriented design with modules (OODwM), is proposed where modules are represented as objects. The proposed OODwM approach is described and the approach is illustrated with an example involving the design of personal computers using the Internet as an implementation environment. The exchangeability inherent in OODwM is shown by exchanging the original selection object in the example implementation with a selection object that includes new constrained evolutionary algorithms.The use of an object-oriented approach for DwM offers several important potential advantages in that the model developed is readily computable, in the reusability of objects, and in the exchangeability of objects with similar interfaces.The main contributions of this paper are fourfold. First, an object-oriented approach to DwM is described. Second, a formalism for DwM using this object-oriented approach is presented. Third, the use of this formalism is illustrated with an Internet-based implementation showing how the formalism can be used for a specific problem, and how objects can be readily exchanged. Fourth, new constrained evolutionary algorithms are presented, together with some initial testing.     

Geometric compensation for automotive stamping die design integrating structure deflection and blank thinning

Targeting to improve dimensional accuracy of automotive body panels, elastic deformation of stamping die structure and blank thinning are considered for compensation on the die surfaces. The thinning distribution on the deformed blank is extracted from stamping process simulation results and converted into first quantitative compensation. The boundary load required for die structural FEM analysis can be automatically mapped from process simulation results by using an updated load mapping algorithm, and the die deflection is then calculated and the deflection of die surfaces is transferred into second quantitative compensation. These two quantitative contributions are referred together for the compensation on the die surface model. The proposed methodologies have been programmed and can be integrated with LS-Dyna and HyperWorks or with Autoform and CATIA. Additionally, a software toolkit used to calculate the contacting ratio between the formed blank and die face has also been developed to automatically evaluate the effectiveness of die face compensation rather than virtually check the contacting ratio. The proposed methodologies and developed software have been verified by a case study of process and die design for an automotive panel part, showing the benefit in improving the contacting ratio.