基于线切割 3B编程CAI软件的探讨

利用VB语言作为编程工具,探讨了开发线切割3B格式自动编程软件的过程.通过该软件,可以直观显示线切割加工的轨迹图及其3B程序.     

拔模金属流动均匀性分析

此文在SUN图形工作站上模拟拔模各道次变形金属流动状况,分析调整各道次的拔模参数,给拔模样板线切割提供数据。同时,用计算机取代模拔实验,实现计算机模拔,使异型材整个拔制过程金属变形均勻,一次拔制出合格的产品。     

改进模板形孔加工的方法

以前对图一所示的大型模板的形孔线切割,一般是钻一个3—6毫米的穿丝孔,经热处理(淬火,回火)后进行形孔线切割。切割后的模板经常出现裂痕(图一),而且厚模板的成形孔壁硬度电不均,也延长了模具的制造周期。     

高强度线切割钼丝的生产

随着现代工业的不断进步,线切割机床的应用范围不断扩大,高强度线切割钼丝的需求量和质量要求也在增加,据统计国内对高强度线切割钼丝的年需求量约为五亿米,在钼制品的生产和加工领域已占有较大份额。现将高强度线切割钼丝的生产过程以及质量状况作一介绍。     

模具线切割开裂和变形的原因与预防措施

此文针对模具线切割过程中产生开裂和变形的现象,从残余应力的产生原因、影响模具线切割开裂和变形的因素较全面的进行了分析和论述,模具线切割开裂和变形是由于其模板内部的残余应力,尤其是热处理残余应力所致,但线切割在一定程度上破坏了模板内残余应力平衡状态,诱发了开裂或变形。根据影响的诸因素,提出了预防开裂和变形的各种措施,但措施的有效性还须因件施策,满足模具的使用寿命和顾及对后序加工的影响。     

微型计算机在环境保护中的应用——(二)程序设计基础知识(上)

使用计算机的一项重要工作就是编写计算机程序,即进行程序设计。所谓程序,就是将计算的问题和原始数据,用算法语言翻译成一组完整的计算机指令。将这组指令输入计算机,就可以得到计算结果了。算法语言也称程序设计语言,它是专门研制的,经国际组织批准,公认,通用的。近年来发展了多种算法语言。如BASIC语言,FORTRAN语言,ALGOL-60语言,COBOL语言等。本讲座只介绍BASIC语言。     

DK7763数控电火花线切割机

我公司生产的DK7763数控电火花线切割机是国内第一台正式通过鉴定的63规格大型数控快速走丝线切割机床,自1994年投入市场以来,深受广大用户的欢迎.DK7763数控电火花线切割机根据大型快速走丝线切割机床的特点,采取了工作台快速运行,X,Y坐标结构分离在同一平面布局,拼接床身,螺距误差补偿等技术,整机布局合理,结构新颖,工作可靠.     

微型计算机在环境保护中的应用——(五)环境管理(下)

环保器材管理使用计算机,已经受到人们的重视。由于篇幅所限这里介绍一项与器材管理类似的程序,自选商店计价程序三、自选商店计算机管理编写出自选商店计价程序。已知某环境保护书刊自选商店的书刊名称及其单价如下表     

电火花线切割放电点位置的检测与评价

为了改善电火花线切割放电加工的稳定性和加工效率,通过检测加工过程中的放电点分布对加工过程进行监控。介绍了电火花线切割加工过程中放电点位置检测原理,检测系统搭建以及放电点位置分布的评价,通过设计实验检测得到加工过程中工件上的放电点位置并进行评价,验证了该系统的检测精度和评价系统的适用性。     

微型计算机在环境保护中的应用 (三)环境质量评价

这一讲将通过环境质量评价法,介绍计算机解法及其程序设计。要了解怎样使用计算机,首先需要懂得怎样定量地解决环境问题,也就是说,在一些环境问题中,采用哪些计算公式,使用哪些初始数据,最后得到什么计算结果。其次才是了解怎样用计算机解题,即编写计算机程序,然后上机运行程序得到结果。一、环境质量评价与计算机这里以对漓江的水质评价为例介绍计算机的应用。对水质进行评价,就是全面评价水质污染状况,其中包括定量地说明水质污染的程度,办法是计算水质污染指数。计算污染指数的方法是,将实际监测的数据与标准值对比、综合,     

Experimental investigation,intelligent modeling and multi-characteristics optimization of dry WEDM process of Al–SiC metal matrix composite

Dry wire electrical discharge machining (WEDM) is an environmentally friendly modification of the oil WEDM process in which liquid dielectric is replaced by a gaseous medium. In the present work, parametric analysis has been fulfilled while dry WEDM of Al–SiC metal matrix composite. Experiments were designed and conducted based on L₂₇ Taguchi's orthogonal array to study the effect of pulse on time, pulse off time, gap voltage, discharge current, wire tension and wire feed on cutting velocity (CV) and surface roughness (SR). Firstly, a series of exploratory experiments has been conducted to identify appropriate gas and wire material based on the values of cutting velocity. After selection of best gas and best wire, they were used for later stage of experiments. Analysis of variances (ANOVA) has been performed to identify significant factors. In order to correlate relationship between process inputs and responses, an adaptive neuro-fuzzy inference system (ANFIS) has been employed to predict the process characteristics based on experimental observation. At the end, an artificial bee colony (ABC) algorithm has been associated with ANFIS models to maximize CV and minimize SR, simultaneously. Then the optimal solutions that obtained through ANFIS-ABC technique have been compared with numbers of confirmatory experiments. Results indicated that oxygen gas and brass wire guarantee superior cutting velocity. Also, according to ANOVA, pulse on time and discharge current were found to have significant effect on CV and SR. In modeling of CV and SR by ANFIS, it was resulted that the proposed method has superiority in prediction of them in the ranges of factors beyond the training condition. Also, association of ANFIS with ABC can find the optimal combination of process parameters accurately according to the confirmatory experiments.     

A Study on Torch Path Planning in Laser Cutting Processes. Part 2: Cutting Path Optimization Using Simulated Annealing

In Part 1 of this paper [beginning on page 54], the heat flow in contour laser beam cutting was calculated by using the finite difference model, and a modified analytic model was developed based on the numerical experiments Part 2 addresses the problem of optimal torch path planning for the 2D laser cutting of a stock plate nested with irregular parts. Under the constraint of the relative positions of parts enforced by nesting, the optimization algorithm generates a feasible cutting path. The simulated annealing technique is adopted for solving the torch path optimization problem to minimize a specified cost function. The objective is to traverse the cutting contours with a minimum path length and, at the same time, to minimize the effect of heat on the cutting path sequence. To minimize the heat effect and avoid overheating, the critical temperature that should be avoided during the whole cutting sequence is considered in this way, a global solution can be obtained in a reasonable time. Several examples are presented to illustrate the effectiveness of the proposed method.     

A Study on Torch Path Planning in Laser Cutting Processes Part 1: Calculation of Heat Flow in Contour Laser Beam Cutting

Conductive heat transfer in contour laser beam cutting is analyzed by using a transient, two-dimensional finite difference model, and the result is combined with a simple analytic model. From the calculation results, the correlation is derived between workpiece temperature and opening angles at a corner in contour cutting. As a result, a modified analytic solution is developed to predict if excessive workpiece heating occurs for given cutting contours in a nested plate. The main objective is to use the computation results in the optimization of torch path planning to provide fully automated CNC programming software for laser cutting. To efficiently apply the analytic model in torch path planning, the critical temperature that should be avoided during the cutting sequence is considered. This leads to an improvement of the cutting quality in the automatic cutting process.     

归州河西沿江高切坡变形破坏及稳定性分析

为了掌握归州河以西沿江公路由于升级改造、工程开挖而产生的大量公路高切坡发育分布特征,总结其变形破坏模式,进而对其稳定性进行分析。在野外实地宏观调查、测量的基础上,通过数据处理,运用赤平投影法对调查区高切坡稳定性进行区划,其中不稳定切坡长约3.8km,占比39.6%,多发育在侏罗系遂宁组(J3s)和聂家山组(J1n)中,主要变形破坏模式为滑移型、倾倒型和剥落型,并根据其破坏模式的差异性提出相应防治对策。     

Parametric study along with selection of optimal solutions in dry wire cut machining of cemented tungsten carbide (WC-Co)

This work deals with parametric study of dry wire EDM (WEDM) process of cemented tungsten carbide. Experiments have been conducted using air as dielectric medium to investigate effects of pulse on time, pulse off time, gap set voltage, discharge current and wire tension on cutting velocity (CV) surface roughness (SR) and oversize (OS). Firstly, a series of exploratory experiments were carried out to identify appropriate gas and its pressure. Afterward, preliminary experiments were conducted to investigate effects of process parameters on dry WEDM characteristics and find appropriate ranges for each factor. Then a central composite rotatable method was employed to design experiments based on response surface methodology (RSM). Empirical models were developed to create relationships between process factors and responses by considering to analysis of variances (ANOVA). To increase the predictability of the process, intelligent models have been developed based on back-propagation neural network (BPNN) and accuracy of these models was compared with mathematical models based on root mean square error (RMSE) and prediction error percent (PEP). In order to select optimal solutions in the cases of single-objective and multi-objectives optimization problems, optimization includes two main approaches. First approach was based on mathematical model and desirability function. Also second approach was designed based on neural network and particle swarm optimization. These approaches were applied in both cases of single-objective and multi-objectives optimization problems and their results were compared with together. Results indicated that selection of air at inlet pressure of 1.5 bar is really appropriate for conducting experiments of next stages. Also, the BPNN creates more accurate prediction rather than mathematical model. Moreover, the BPNN-PSO approach was more efficient in optimization of process rather than mathematical model-desirability function in respect with validation tests.     

Ball end milling mechanistic model based on a voxel-based geometric representation and a ray casting technique

Prediction of machining forces involved in complex geometry can be valuable information for machine shops. This paper presents a mechanistic cutting force simulation model for ball end milling processes, using ray casting and voxel representation methods used in 3D computer graphics field. Using this method, instantaneous uncut chip cross sectional areas can be extracted, which can be used in cutting pressure coefficient extraction and machining simulation including machining forces and geometry of the workpiece. The major advantage of the proposed scheme is that it can simulate milling processes with arbitrary cutting tool geometry on a workpiece with complex geometry, using an algorithm with constant time complexity. A series of cutting experiments were carried out to validate the model.     

Influence of packing media on nitrogen removal in a subsurface infiltration system

Influence of packing media on nitrogen removal in a subsurface infiltration system was studied. System A was filled with loamy soil and system B was filled with mixed soil of 75% red clay with 25% cinder. Both systems were fed with sewage at the same hydraulic loading of 2 cm/d at continuous operation mode. The same excellent removal performances of COD and T-P could be achieved in both infiltration systems with removal rates about 85% and 98%, respectively. In system A, NH4^ -N removal rate was as high as 96.5% and T-N removal rate was relatively much lower as 55.7%. And in system B, NH4^ -N removal rate was as low as 75.4% and T-N removal rate was relatively much higher as 75.5 %. The difference was attributed to different soil oxidation-reduction condition that was greatly influenced by soil texture in subsurface infiltration system. Loamy soil led to oxidative condition that was favorable to nitrification and disadvantageous to denitrification. The results were just adverse to the system filled with clay. Intermittent operation was adopted to improve nitrogen removal in system B. NH4^ -N removal rate could be increased to about 95% and T-N removal rate could be increased to about 90% at intermittent operation mode in system B. Analysis of nitrogen removal mechanisms indicated that nitrification-denitrification was the primary nitrogen removal path in subsurface infiltration system and crop uptake was another important nitrogen removal way, It was the key to improve the total N removal performance that a suitable packing soil was available to present favorable oxidation-reduction condition for simultaneous nitrification and denitrification.     

An Experimental Study of Dust Generation During Dry Drilling of Pre-Cooled and Pre-Heated Workpiece Materials

The generation of fine dust during dry machining is a serious problem both for the environment and for workers. During machining, the fine dust particles generated remain suspended in the air for long periods, during they can be inhaled by workers. The quantity of dust generated is influenced by factors such as material type and heat treatment condition, temperature, and the associated chip formation mode. The aim of this work is to discover how these parameters influence dust generation during dry machining, which could lead to the control of dust production in the future. The materials tested are the wrought 6061 and foundry A356 aluminum alloys and 70-30 brass. It is found that pre-cooling a workpiece material leads to changes in chip formation, in the reduction of cutting forces, and hence in a reduction in fine dust generation by at least 70%, depending on the materials and cutting conditions used. Also, pre-heating the workpiece increases chip ductility and dust production levels.     

天山低层云水资源中冰粒子物理属性年际变化

采用2003 年1 月至2012 年12 月美国宇航局NASA 发布的CERES SSF Aqua MODISEdition 1B、2B和3A云资料,从冰水柱含量、云等效温度、云等效高度以及冰粒子等效直径4 个云物理宏微观属性考察天山低层云水资源年际变化特征.结果表明:冰水柱含量均值在32.7~92.0 g/m²之间,云等效温度均值在214.9~257.3 K之间,云等效高度均值在3.9~5.7 km之间,冰粒子等效直径均值在12.7~22.4 μm之间.冰水柱含量、云等效高度、云等效温度均呈降低的年际变化特征,冰粒子等效直径呈增加的年际变化特征.     

公共性视野下的乡村生活垃圾处理困境分析研究 ——以B村为个案

以B村为个案,对B村村民的生活垃圾认知,生活垃圾的组成成分及该村生活垃圾处理方式进行了简要分析.运用公共性相关理论深入探讨了B村生活垃圾处理困境,结果表明,村民公共精神、公共规则的缺乏与村庄公共物品的匮乏导致B村生活垃圾得不到妥善地处理.指出要在培养村民公共意识的基础上,加强政府的投入,建立健全公共卫生设施;发挥村干部的优势,完善相关的村规民约及提高村民的环保意识等,可有效解决乡村生活垃圾的处理困境.