宝钢大口径直缝焊管中工具连接架的制造

主要介绍国内第一条生产线宝钢大口径直缝焊管工程(UOE项目)中U成型机区工具连接架的制造过程。利用各种装夹工具、吊具及焊接方法来解决加工过程中零件长而薄易变形的困难,利用高精度水准仪和经纬仪随时检测加工过程中零件变形情况,并控制安装基准与加工定位基准一致以保证工具连接架的加工。     

V型块综合定位误差的分析计算

通过对V型块的制造及安装误差进行全面的分析,当加工大批量圆柱零件时若设计基准为外圆中心,充分考虑采用V型块定位时产生定位误差的各种因素,得出加工类似零件该道工序的综合定位误差计算公式。     

发动机缸体加工粗基准选择与定位方式的研究

缸体加工粗基准的选择决定了缸孔壁厚均匀性,直接影响发动机工作过程中缸孔内径圆柱度的变化.传统的粗基准的选择方案与缸孔外壁之间积累误差很大,使得加工后的缸孔壁厚差离散性大,难以满足新产品的设计要求.通过研究分析,在新建生产线中对粗基准作了优化选择,直接选取了铸造缸孔外壁及与其在同一副型芯上形成的水堵孔作为粗基准,并对定位方式作了改进,大大提高了缸孔壁厚均匀性.文章还介绍了另外两种粗基准选择方案,为不同机型缸体加工的粗基准选择提供借鉴.     

基于不同工艺过程的毛坯尺寸基准的研究

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,文章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、降低材料降耗有重要意义。     

轴箱体内孔加工圆柱度超差分析及夹紧力计算

在轴箱体零件加工过程中存在内孔圆柱度超差现象。初步分析认为是四爪卡盘夹紧工件引起的夹紧变形所致。文章分别分析计算了在一定切削用量下精车轴箱体端面及内孔时需要的夹紧力、用四爪卡盘夹紧工件实际产生的夹紧力及其引起的变形，利用材料力学、弹性力学相关定律，推导出由夹紧变形引起的形状误差的计算公式，确定了轴箱体内孔加工圆柱度超差的原因，并提出了改进措施。     

细长锥孔零件精密加工工艺方法

锥型滤波小孔零件是神光-Ⅲ空间滤波器中重要的滤波元件,其加工质量直接影响主激光的滤波效果.该零件为精密细长锥孔结构,孔径与孔深比达1:25、小端口径小于φ2mm、同轴度要求小于φ0.005mm、光洁度小于Ra0.2 μm.文章基于延伸和复用基准减小误差的加工思路、采用慢走丝切割锥孔的工艺方法,优化工艺路线、装夹方法和工艺参数,实现零件同轴度优于φ0.004mm、光洁度优于Ra0.1 μm.该工艺方法加工质量稳定、生产效率高,满足该重大光学工程项目对精密锥孔类零件多规格、小批量的应用需求.     

毛坯尺寸基准设计方法研究

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,为了实现粗加工余量公差最小以及加工面与非加工面尺寸及位置误差最小的目的,提出了基于不同工艺过程的毛坯尺寸基准设计的新方法,该方法对提高机械产品质量、降低材料损耗有重要意义.     

提高箱体零件的加工精度

对加工面的相互位置精度提出严格要求是箱体零件的加工特点。工件在自动线上从一个工位输送到另一个工位的多工序加工过程中要保证这些要求。 研究现有自动线上箱体零件的安装情况得出:实际安装误差远远大于计算值,而在精加工工序中则近似于允许值。这就是在自动线上加工箱体零件孔和平面空间位置精度难以保证的主要原因之一。 一般来说,安装误差包括定位误差(在定位过程中毛坯相对刀具定向)、由于夹紧力引起的夹紧误差以及夹具元件制造不精确     

基于自由度变动的定向公差计算方法分析

在分析物体结构特征的基础上,指出了定向几何公差中平行度和垂直度与几何要素自由度的关系;建立了定向误差相关要素的数学模型;分类给出了定向误差位置链中基准不变三环位置链的计算方法,为数字化加工过程中定向公差的设计和工艺计算提供了一种方法。     

精密外圆磨削圆柱度在位测量与补偿工艺

圆柱度是评价轴类零件加工精度的重要指标,通过对精密轴类零件外圆磨削过程中圆柱度误差产生机制的研究,获得适用于精密外圆磨削的圆柱度误差在位测量工艺,并实现可视化定量在位补偿,大大提高了传统外圆磨削的精度和效率,减轻了对操作者经验的依赖程度。     

工艺参数对高强钢管单道次缩径旋压成形质量的影响

基于ABAQUS/Explicit平台建立了高强钢管形件双旋轮无芯模缩径旋压成形有限元模型,对其单道次缩径旋压成形过程进行了数值模拟,获得了旋压成形的应力、应变分布规律及工艺参数对成形质量的影响规律,并通过试验验证了数值模拟的可靠性。结果表明:最大残余应力出现在直壁段和开口端外表面,最大等效应变出现在锥形缩口与直壁过渡部分、直壁段和开口端外表面,应力、应变集中区在旋压过程中容易产生过度减薄;随着压下量Δ的增加,壁厚最大减薄量增加、圆柱度增大,在Δ=3 mm时圆度最小;随着进给比f的增加,壁厚最大减薄量减小、圆柱度减小,但平均外径与理想值偏差较大,f=1.0 mm·r-1时综合成形质量较好;随着旋轮圆角半径rρ增加,壁厚最大减薄量减小、圆柱度减小,但在rρ=10 mm时沿轴向截面圆度最小。     

Evaluation of form data using computational geometric techniques—Part II: Cylindricity error

The form tester having a straight datum in addition to rotational axis provides the cylindricity data. Due to misalignment between axis of the component and instrument axis, and size-suppression inherent in such measurements, a limacon-cylinder has to be used for cylindricity evaluation. For the first time, an attempt has been made in the present work to establish the limacon-cylinder using computational geometric techniques. Concepts involved in the construction of limacon from 2D control hull as brought out in Part I are further extended in this Part II to establish the limacon-cylinder. The algorithms developed in this paper have been applied for minimum circumscribed, maximum inscribed and minimum zone evaluations of the data available in the literature. The proposed algorithms are fast and yield accurate results, and can be implemented in computer-aided form measuring instruments.     

Evaluation of form data using computational geometric techniques—Part I: Circularity error

The present work deals with evaluation of form error from the measured profiles obtained using a form tester, namely roundness/cylindricity measuring instrument. In Part I, details of circularity evaluation are presented. Due to eccentricity in component setting and radius-suppression inherent in the measurement, circularity error has to be evaluated with reference to a limacon. A computational geometry-based algorithm is proposed for establishing minimum circumscribed, maximum inscribed and minimum zone limacons. A new type of control hull for directly constructing equi-angular diagrams and a new procedure for updating are introduced. Validation has been done with bench-mark data set and corresponding results available in the literature. Being geometry-based algorithm, it is simple to follow and each iteration can be visualized and interpreted geometrically. On comparison with simplex search method, the proposed algorithm is found to be computationally efficient in terms of accuracy and time taken. The proposed methods can be easily implemented in computer-aided roundness measuring instruments. Extension of this work for evaluation of cylindricity error has been dealt in Part II.     

混合策略改进鲸鱼优化算法在圆柱度误差评定中的应用

机械零件的形位精度对其互换性以及功能质量具有极其重要的影响,其中圆柱度误差是评价回转类零件精度的一个重要指标。设计一种基于混合策略改进的鲸鱼优化算法,以提高圆柱度误差在评定过程中的精度和收敛速度。首先,在初始种群的生成中引入Tent混沌映射和非线性参数,以提高解的质量;其次,为了改善算法的局部搜索能力,在螺旋式位置更新阶段引入一个自适应权重系数;最后,在随机搜寻阶段引入莱维飞行从而提高全局搜索能力。通过采用不同优化算法的实验和结果对比分析,提出的算法在圆柱度误差评定精度和速度方面均有一定提升。     

Deformation characteristics during Y-shaped tube hydroforming of 6061 aluminum alloy

To manufacture lightweight tube components for aerospace oil circuit systems, an experiment was run to investigate the deformation characteristics on Y-shaped tube hydroforming of 6061 aluminum alloy. Both strain state and metallurgical structure indicate that there are four kinds of prevailing defects during Y-shaped tube hydroforming: bursting, lack of cylindricity, wrinkling, and thinning due to the poor plastic property of 6061 aluminum alloy. The danger of bursting prevails at the early stage of the operation as a result of excessively high internal pressure. In contrast, wrinkling prevails after the middle stage of the operation as a result of excessively axial feeding and cannot be eliminated during subsequent deformation. Lack of cylindricity is mainly because of insufficient axial feeding and internal pressure but can be eliminated by increasing internal pressure. Elongation and compression deformations are originated on protrusion and main pipe of Y-shape tube respectively all the way through the bulging process. Consequently, minimum and maximum thicknesses are at the top of protrusion and the bottom of Y-shape tube respectively, which induces a V-shape borderline of thickness distribution. According to the excessive plastic deformation, microstructure evolution is originated. Crystal grain of protrusion is elongated and its grain size is about 150 μm. In contrast, crystal grain of the middle zone of main tube is refined greatly, which grain size is 50 μm, decreased by 75%. These are useful to improve the component.     

传动轴花键轴叉制造工艺革新

改进传动轴花键轴叉金加工工艺,有效地缩短工艺流程,实现工艺基准统一;提出花键轴叉中频感应加热淬火方法,保持花键轴叉两叉耳根部的原有强度,有效解决了热处理变形;开发铣端面、打中心孔的工艺装备,消除了因定位基准转换造成的误差,保证了零件加工精度;改进拉花键工艺和夹具,提高了加工效率,定位较为准确,能更好地保证加工后的花键轴叉的产品质量。实践证明:通过改进花键轴叉的制造工艺,提高了生产效率,降低了成本。     

Assessing cylindricity for oblique cylindrical features

This research investigates the algorithmic aspect of cylindricity assessment. With the surface points measured with coordinate measuring machines (CMMs), cylindricity can be assessed under different kinds of reference cylinders. In order to explore the full capability of CMMs, supplementary methodologies for finding a fine-tuned axis of the cylinder have been developed, including rotational devices, quasi-linear equations and complicated procedures. This research derives a mathematical model so that the axis of the reference cylinder can be tuned algorithmically. The global optimum of the model, which yields the assessment of cylindricity, is computed by using a simulated annealing algorithm, namely Hide-and-Seek.     

基于本体的圆柱度规范完整性自动检验

针对不完整的公差规范导致认证人员提出多样化的认证方案，使规范设计意图与认证方案不一致的问题，以工程中典型的圆柱度为研究对象，提出一种基于本体的圆柱度规范完整性自动检验方法。根据圆柱度规范与认证之间的映射关系构建自动检验工程语义模型，将该工程语义模型转化为以描述逻辑为数学基础的本体模型，并提出了完整性自动检验算法，最后在实例中结合该算法来验证提出方法的有效性。结果表明：该方法能有效地对圆柱度规范完整性进行自动检验。     

Assessment of Force-Induced Errors in CNC Turning

This paper describes a procedure to evaluate the force-induced errors occurring in cylindrical turned components. This procedure is based on a model which represents the real-time stiffness of the spindle-bearing system and the rotational clamping stiffness of the component held in a chuck. The stiffness values are determined from a single cutting test in which the deflection of a test bar is measured. The model also takes into account the stiffness of the component and toolpost. The model is validated by comparing the predicted error in the cylindricity of a machined bar with the measured value.     

激光位移传感器在圆柱度误差检测中的应用研究

为了提高圆柱度测量的效率和准确性,针对目前手工检测效率低等缺点,提出一种以三维激光位移传感器的测量原理为依据的光电非接触圆柱度测量方法。与传统方法相比,该方法首先搭建了以回转主轴和伺服执行机构为主的测量控制系统平台;其次,利用机械装置的相对运动,通过传感器采样测量物体各测量截面的信息,实现圆柱度误差测量。