工艺设计过程中的切削体分解组合策略

为实现工艺设计过程中对产品设计数据的有效重用,提出了一种切削体分解组合策略。该策略利用对切削体的分解组合,向工艺设计提供所需的基本工艺路线、工艺模型、尺寸公差等工艺数据。为生成符合工艺要求的切削特征,阐述了切削体分解算法和分割面的生成方法;研究了几何约束、工艺约束下的分割面分解优先级确定规则;探讨了单元切削体组合条件和优先组合策略。通过实例阐述了该策略下的工艺设计过程,验证了该策略的可行性和有效性。

基于工序切削体的三维公差模型"

在工序特征识别的基础上,提出了一种基于工序切削体的三维公差建模方法。该方法视毛坯模型为零件模型和工序切削体集合的装配体,利用小位移旋量描述零件和工序切削体的公差旋量,计算各旋量的变动约束;构建工序切削体集合的公差网络图,探讨设计公差在工序公差网络中的传播机制,建立工序公差累积模型,为工序公差设计提供基础。最后,通过实例验证该方法的有效性,并说明基于该建模理论的工序公差分配方法。

基于扩展属性邻接图的切削体过程模型统一描述方法研究

为了实现工艺设计过程中对产品设计数据的有效重用,以扩展属性邻接图为基础,描述了切削体扩展属性邻接图、工序切削特征模型和单元切削体模型,最后提出扩展属性邻接矩阵和扩展属性信息表两种特征信息存储方式。

基于切削体分解的角盒类零件工艺模型参数化

针对角盒类零件工艺信息利用率低、工艺设计及数控编程需人员重复劳动且效率低下的问题,提出一种基于切削体分解的工艺模型参数化自动生成方法。分析零件典型特征,定制干涉与非干涉、叠加和不可叠加原则进行典型件归类。结合零件加工需求,构建四边留框内接搭台的典型工艺模型及典型工艺。基于体分解原理,以参数化负实体构建切削单元体。利用CATIA软件以装配方式建立参数化模型,并进行参数实例化验证。结果表明:利用该方法能够有效重用现有工艺信息,避免特征组合造成的参数畸形问题,实现典型工艺模型的参数化与实例化,提高工艺编制及数控编程效率。

涡轮增压器壳体的复合材料切削加工特性研究

涡轮增压器壳体的复合材料因其结构和性质在切削加工中面临独特的挑战。探讨了涡轮增压器壳体的功能、应用以及材料选择的重要性。详述了复合材料的基本性质,特别是其在涡轮增压器壳体中的应用和力学性质。进一步分析了切削过程中的挑战如切削力、角度的变化以及工具磨损问题。并提出了一系列的优化策略,涵盖了工具选择、切削角度参数以及冷却液和润滑策略。旨在提高切削效率,确保工件的质量,并延长工具的使用寿命。

两体微切削磨损理论——两维粗糙度模型

本文独立地推导了考虑硬表面和软表面粗糙度影响的两体微切削磨损理论模型。这个模型直接利用表面轮廓高度分布密度函数进行计算，和现在生产实际中广泛应用的表面轮廓仪相衔接，非常方便。利用这个模型对在载荷一定条件下两表面多次相对滑动过程中软表面粗糙度及磨损率的变化作了数值计算，从而给出了一系列结果。

数控车床加工中锥体切削中的计算问题

利用单一形状固定循环指令切削锥体以及在锥体上切削螺纹时,其中有一参数I应是我们切削锥体或在锥体上切削螺纹时,切削起点与切削终点的半径差。

一种工序模型自动生成方法

通过分析目前三维计算机辅助工艺设计(Computer Aided Process Planning,CAPP)工艺过程可视化表达存在的问题与难点,在三维CAPP中引入工序状态模型的概念,利用工序状态模型完成三维工艺过程的可视化表达。提出了工序状态模型自动生成的方法,分析了该方法的业务需求及基本原理,给出了该方法的基本流程,深入分析了特征切削体参数化构造法及型腔特征切削体深度优先构造法。通过实例验证了该工序模型自动生成方法的有效性。

简述清除管线油焦专用设备的制作和使用方法

2013年阿尔及利亚索拉信炼油厂35万吨/年催化裂化沉降器油气管线清除结焦人工作业施工难度大,为了解决油气线清除结焦作业缓慢的难题,同时降低作业风险,提高施工效率,针对油气线结焦清理的问题设计制作了清除油焦专用设备,该设备由切削冲击体和动力风两部分组成,其中切削冲击体包括:冲击刀头及导向套筒;动力风镐、冲击板、平衡配重(包括两个配重、横档、导向板和导向柱);动力风包括:空气压缩机及风线等。清除结焦作业时,把切削冲击体放置在油气管线内,通过操作拉绳和动力风线开关作业。

An appraisal of techniques and equipment for cutting force measurement

Current research focussed on the assessment of metal machining process parameters and on the development of adaptive control, shows that machine performance, work-piece and tool material selections, tool life, quality of machined surfaces, the geometry of cutting tool edges, and cutting conditions are closely related to the cutting forces. This information is of great interest to cutting tool manufactures and users alike. Over the years there have been significant developments and improvements in the equipment used to monitor such forces. In 1930 mechanical gauges were replaced by resistance strain gauges, and some 30 years later compact air gauge dynamometers were invented. Since this time intensive research has continued being directed to- wards developing new approaches to cutting force measurement. The Kistler Company, well-known manufacturer of acceleration and piezoelectrical dynamometers, has worked in this field for more than three decades, and developed very sensitive devices. While leading manufacturing research laboratories are often equipped with this technology, classical electrical strain gauges and other dynamometers of individual designs are still commonly used in industry. The present paper presents data obtained using different techniques of force measurement in metal machining processes. In particular, areas of uncertainties, illustrated through results concerning the turning process, are analysed, leading to an appraisal of the current status of these measurements and their significance.

Investigation of Nanofluids as Potential Cutting Fluids in Gear Hobbing Processes of AISI 4118 Steel

The present work focuses on the performance of nanofluids called CN46-NanoAl2O3.80 formulated by using dispersions of nano aluminum oxide （Al2O3） in the ISO VG46 industrial oil on machining performance during gear hobbing of AISI 4118 steel. In machining gears, hobbing is one of the most important processes, especially to produce various gear shapes for adapting to diverse applications. However, the demand for high quality brings attention to product quality, particularly the roughness of the machined gear surface because of its effect on product appearance, function, and reliability. For additional improvement, applying nanofluids may produce superior product quality, as the rolling action of billions of nanoparticle units in the tool chip interface can significantly decrease the friction led to reduce the cutting forces. In addition, the characteristics of heat transfer of nanoparticles can contribute to reduce tool wear. In this experimental study, the performance of nanolubricant compared with the case of using ordinary cutting-fluid systems in the existing production line is investigated. The experimental results reveal that the tool life of the hob is significantly enhanced of 55.2%, gear surface roughness is smaller （27.3%）, and gear accuracy is significantly increased by using the nanofluid. This result, therefore, shows a promising solution to achieve the engineering-economy effectiveness in gear machining.

Chip formation dependence of machining velocities in nano-scale by molecular dynamics simulations

In this study, molecular dynamics simulations were carried out to study the effect of machining velocities on the mechanism of chip formation in nano-metric copper. A wide range of cutting velocities was performed from 10 to 2000 m/s, and the microstructure's evolution from a crystalline state to an amorphous state was studied. At the low machining velocity, dislocations were generated from the surface in front of the tool, and the immobile dislocation deduced by the cross slip of dislocation was observed. At the high machining velocity, no crystal dislocation nucleated, but instead disorder atoms were found near the tool. Temperature near the tool region increased with the increasing machining velocities, and the temperature had an important effect on the phase transition of the crystal structure.

Research on the nanometric machining of a single crystal nickel via molecular dynamics simulation

Molecular dynamics simulations are employed to study the nanometric machining process of single crystal nickel. Atoms from different machining zones had different atomic crystal structures owing to the differences in the actions of the cutting tool. The stacking fault tetrahedral was formed by a series of dislocation reactions, and it maintained the stable structure after the dislocation reactions. In addition, evidence of crystal transition and recovery was found by analyzing the number variations in different types of atoms in the primary shear zone, amorphous region, and crystalline region. The effects of machining speed on the cutting force, chip and subsurface defects, and temperature of the contact zone between the tool and workpiece were investigated. The results suggest that higher the machining speed, larger is the cutting force. The degree of amorphousness of chip atoms and the depth and extent of subsurface defects increase with the machining speed. The average friction coefficient first decreases and then increases with the machining speed because of the temperature difference between the chip and machining surface.

An adaptive smoothed particle hydrodynamics for metal cutting simulation

Normally large amounts of particles are required to accurately simulate the metal cutting process,which consumes a lot of computing time and storage.Adaptive techniques can help decrease the number of particles,hence reducing the runtime.This paper presents a novel adaptive smoothed particle hydrodynamics(SPH)method for the metal cutting simulation.The spatial resolution changes adaptively according to the distance to the tool tip by the particle splitting and merging.More particles are selected in the region where the workpiece and the tool are in contact.Since the contact region constantly changes during the cutting process,two quadrilateral frames are adopted in the adaptive algorithm to dynamically change the distribution of particles.One frame for the refinement,the other for the coarsening.These frames move at the same speed as the tool.To test the computational efficiency,the metal cutting process is simulated by using SPH with three different adaptive approaches.Numerical results show that the proposed adaptive algorithm with dynamic refinement and coarsening can significantly optimize the runtime.