汽车半轴锥齿轮的精密成形技术和机加工专用夹具研究

提出了采用普通锻压设备进行坯料准备、高精度冷摆辗机成形半轴锥齿轮精锻件的成形新工艺,研究了成形工步的坯料形状、成形工艺参数、模具结构以及精锻件后续加工的工装夹具结构等一系列技术问题。达到了齿形精度高、齿部强度高、啮合质量好、齿轮模具的使用寿命高、材料利用率高、生产成本降低及可以进行大批量工业生产的目的。     

不锈钢表面的电化学机械复合抛光

不锈钢板在生产和装饰材料中得到越来越多的应用,其表面粗糙度对产品质量有着重要影响。研究了不锈钢板的高效电化学机械抛光,介绍了一台由立式铣床改装的电化学机械复合抛光装置,讨论加工电压、磨轮压力与加工效率的关系以及加工电压对表面粗糙度的影响。研究结果表明,电化学机械复合加工可以得到更高的加工效率和更好的加工质量。     

基于湿纸编码的多像素值差密写

提出了一种基于湿纸编码的多像素值差(MPVD,multi-pixel value differencing)密写方法。首先用光栅扫描的方式将载体图像划分为若干不重叠的四像素的小块,再将每个小块的4个像素值分别与其中最小像素值求差,应用湿纸密写原理,通过选择适合人眼分辨能力的"干燥区域",将改进的Arnold方法置乱的秘密信息嵌入。模拟实验结果表明,和最低有效位法(LSB)和像素值差法(PVD)相比,本文方法嵌入量高,安全性好,提取简单。     

Experiment study on electroplated diamond wire saw slicing single-crystal silicon

This paper conducted the slicing experiments of single-crystal silicon using a reciprocating electroplated diamond wire saw. The machined wafer topography and wire wear were observed by using scanning electron microscope (SEM). The influences of process parameters and cutting fluids on single-crystal silicon wafer surface roughness (SR), subsurface micro-crack damage (SSD) depth, total thickness variation (TTV) and warp were investigated. The bonded interface sectioning technique was used to examine the cut wafers SSD depth. Study results show that a higher wire speed and lower ingot feed speed can produce lower wafer SR and SSD; the lower warp of wafer needs lower wire speed and ingot feed speed; and low wafer TTV can be obtained by an appropriate matching relationship between wire speed and ingot feed speed. The synthetic cutting fluid has a better total effect to improve the wafer quality. The pulled-out of diamond abrasives is the main wear form of wire, which indicates that more research on improving the abrasives retaining strength on wire surface should be investigated in fixed-abrasive wire manufacturing process, in order to improve the wire life and wire saw machining process.     

加工误差对齿廓重迭干涉的影响

应用具体实例,研究了加工误差对少齿差内啮合齿廓重迭干涉的影响,并提出相应的解决方法。     

波导隙缝阵列平板天线的精密加工技术

介绍了波导隙缝阵列平板天线的精密加工和制造技术，通过工艺分析，给出了平面波导焊接艺分解结构，确定了主要关键技术，采用了多种控制加工变形方法，实现了焊前高精度装配要求，并借助误差分析原理验证了工艺方法的正确性。     

深小孔脉冲电解加工精度控制研究

为了实现电解加工深小孔的精度控制,建立线性去除率动态数学模型,分析影响动态方程的工艺参数,通过在镍基合金上进行电解加工深小孔试验,分析了脉冲宽度、工具电极进给速度、工具电极绝缘层有无裸露对深小孔加工精度的影响。结果表明：采用较大的脉冲宽度、较大的工具电极进给速度、绝缘层覆盖全部工具电极,有利于提高孔的加工精度。     

基于OpenGL技术的数控车床虚拟仿真系统研究

当数控代码庞大、加工的轴形状复杂时,如何实时、逼真地仿真切削过程成为实现数控加工过程三维仿真系统的难点。本文介绍了利用OpenGL技术和面向对象的思想实现数控车床三维虚拟仿真的方法。重点分析了三维虚拟对象的绘制,面向对象的数据存储方式和面向对象的过程实现方法。基于该方法,开发了实用的数控车床三维仿真系统,实验结果验证了该方法的可行性与高效性。     

数控加工零件工时估算的神经网络方法研究

为了快速合理地估算数控加工零件工时，提出了零件相似检索规则和算法，该算法应用神经网络获取典型零件的工时规律，并按此预测当前零件的加工工时。经实验表明这种算法可以快速有效地得到数控加工零件的工时估算值，为工厂技改实施、投资咨询及产品设计提供了辅助决策支持。     

Changes in dry matter concentration gradients in stored apples

Longitudinal and transverse dry matter concentration gradients were measured in Cox's Orange Pippin apples at harvest and during storage. Dry matter concentration was higher at the calyx end of the fruit at harvest than in the central zone and at the stalk end. This difference was maintained as dry matter concentration in the whole fruit declined during cold storage. Dry matter concentration decreased from the peel to the core in median transverse slices at harvest but this gradient diminished during storage at 4°C in either air or 1·25%v/v O₂. After 11 weeks' storage dry matter concentrations became generally lower in all zones of the air-stored fruit than those in apples stored in 1·25% v/v O₂, but transverse distribution patterns of dry matter were similar in apples in either regime throughout storage. Proportions of dry matter in the outer zones declined whilst those in the inner cortex and core increased. The relevance of these changes to the quality of stored apples is discussed.