加工误差的综合分析和铣夹具加工应用实例

在机械加工生产中 ,使用各类夹具是确保加工精度、提高生产效率和减轻工人劳动强度的重要手段。根据机床和夹具的特点制订机床夹具的磨损极限是保证产品质量的必要条件。基于对零件加工误差的综合分析讨论了加工误差的分配原则 ,并根据铣床及其铣床夹具的结构类型特点 ,结合生产实践的经验 ,讨论了铣床加工误差构成及铣夹具磨损极限值的计算方法 ,并给出了典型铣夹具磨损极限值的计算实例。     

加工误差的综合分析和铣夹具加工应用实例

在机械加工生产中，使用各类夹具是确保加工精度、提高生产效率和减轻工人劳动强度的重要手段。根据机床和夹具的特点机床夹具的磨损极限是保证产品质量的必要条件。基于对零件加工误差的综合分析讨论了加工误差的分配原则，并根据铣床及其铣床夹具的结构类型特点，结合生产实践的经验，讨论了铣床加工误差构成及铣夹具磨损极限值的计算方法，给出了典型铣夹具磨损极限值的计算实例。     

夹具加工的误差综合分析和误差分配

在机械加工的成组和批量生产中，使用各类夹具是确保加工精度、提高生产效率的重要手段。制订机床夹具的磨扣极限是保证产品质量的必要条件。本文基于对零件加工误差的综合分析和误差分配原则，讨论了夹具磨损极限值的计算方法。     

钻夹具磨损极限偏差的计算

在机械加工的成批生产和大批、大量生产中，使用各类夹具是确保加工精度、提高生产效率的重要手段。制订机床夹具的磨损极限是保证产品质量的必要条件。根据钻床夹具的结构类型特点，基于对零件加工误差的综合分析，结合生产实践的经验，讨论了钻夹具磨损极限偏差的计算方法和误差分配原则，并给出了典型钻夹具磨损极限偏差的计算实例。     

车床夹具失效的判定

在生产中,车床夹具经过一定时间的使用,因定位元件的磨损而造成所加工的产品零件质量不合格。这种现象称为夹具的失效。在设计时必须给出定位元件的磨损极限值,并根据生产批量的大小给出夹具的检验周期。磨损极限值及检验周期都应写在夹具总图的技术条件中。质量检验部门根据检验周期对夹具进行周期检验。车床夹具的失效与否是由夹具的定位元件的磨损极限值来确定的。磨损极限值既是判定夹具     

夹具精度的检验周期的研究

夹具在使用过程中的磨损对工件的加工精度影响很大。这里通过一个实例讨论了夹具精度的检验周期的计算方法。     

采用概率法计算定位误差

<正> 1.前言在夹具设计中,计算定位误差(△_D)时,通常采用基准位移误差(△_y)与基准不重合误差(△_B)的代数和求得,即△_D=|△_y±△_B|。而△_y和△_B的数值均取定位元件和被加工零件有关尺寸的公差值。当两者影响同向时,则计算结果△_D很大,反之又极小。这种处于极限值的状态实际是不多见的。由加工误差统计规律可知,一批零件的尺寸误差主要是随机误差。零件的实际尺寸绝大部分处于中间尺寸(lmax+lmin)/2段,接近极限值的是少数。因夹具上的定位     

基于车铣技术的刀具磨损和破损分析

在车铣加工中心上，分别采用硬质合金和TiN涂层硬质合金刀片，对铝合金和不锈钢工件进行了车铣加工的刀具磨损试验，研究分析了车铣刀具的磨损和破损特征。研究表明，车铣铝合金的刀具磨损机理主要以刀具表层材料的黏结磨损为主，而车铣不锈钢的刀具磨损机理主要以刀具表层材料的疲劳-剥落磨损为主。车铣不锈钢时，刀具的损坏形式常常以微崩刃、前刀面的剥落和碎断等破损形态为主。     

根据刀尖轨迹计算刀具磨损量

影响零件加工尺寸精度的因素有很多，包括工件的定位误差、夹具的设计尺寸精度，刀具的制造精度及磨损、机床的精度等。在车床上加工一个R较小的凹槽时，刀具的磨损对零件尺寸精度的影响很大。     

车铣复合加工的刀具磨损强度分析

在车铣复合加工中心上,进行了车铣加工高强度钢工件材料的刀具磨损强度实验,分析了车铣切削用量对刀具磨损强度的影响.研究表明,在影响车铣刀具磨损的切削用量中,切削速度对车铣刀具的磨损强度影响最大.并以车铣刀具的磨损实验为基础,以切削速度为变量,建立了车铣高强度钢的刀具磨损强度分析模型.     

Prediction and compensation of machining geometric errors of five-axis machining centers with kinematic errors

Kinematic errors due to geometric inaccuracies in five-axis machining centers cause deviations in tool positions and orientation from commanded values, which consequently affect geometric accuracy of the machined surface. As is well known in the machine tool industry, machining of a cone frustum as specified in NAS979 standard is a widely accepted final performance test for five-axis machining centers. A critical issue with this machining test is, however, that the influence of the machine's error sources on the geometric accuracy of the machined cone frustum is not fully understood by machine tool builders and thus it is difficult to find causes of machining errors. To address this issue, this paper presents a simulator of machining geometric errors in five-axis machining by considering the effect of kinematic errors on the three-dimensional interference of the tool and the workpiece. Kinematic errors of a five-axis machining center with tilting rotary table type are first identified by a DBB method. Using an error model of the machining center with identified kinematic errors and considering location and geometry of the workpiece, machining geometric error with respect to the nominal geometry of the workpiece is predicted and evaluated. In an aim to improve geometric accuracy of the machined surface, an error compensation for tool position and orientation is also presented. Finally, as an example, the machining of a cone frustum by using a straight end mill, as described in the standard NAS979, is considered in case studies to experimentally verify the prediction and the compensation of machining geometric errors in five-axis machining.     

接触变形对工件加工误差的影响

基于工件的准静态受力分析 ,运用经典Hertz接触理论 ,计算夹具 工件接触区的变形。根据多刚体运动学 ,建立表面加工误差和接触变形的关系 ,对加工误差进行预报。此方法也可用来计算定位基准误差对加工误差的影响。     

Self-generation of machining precision and its realization in lapping of super precision solid balls

This paper presents the principle of self-generation of machining precision by explaining its basic concept and five necessary conditions for forming a system with self-organization capability. A self-generation system is a kind of system with self-organization capability. The self-generation of machining precision for solid balls with super precision is emphatically explained. From the viewpoint of self-organization, there are three types of systems including system S1 with the self-regulation capability, S2 with the self-determination capability of goals, and S3 with the self-organization capability. Although they are all closed loop control systems, they have different constructions and functions. Necessary conditions for achieving self-generation of machining precision are given. Establishment of the system for machining solid balls with super precision is discussed. Self-generation of machining precision for solid balls with super precision on the basis of the capability of self-removal of errors is presented. Self-generation includes the ability of self-removal of errors for solid balls, convergence of self-removal of errors, self-generation of precision, and self-generating system for the given.     

曲面铣削中刀具路径的自适应研究

如何高效率、高精度的完成自由曲面的数控加工。是机械制造领域的研究工作者一直追求的目标,针对这一问题,提出了全曲面误差和均匀粗糙度加工的概念。建立了通实现这种加工的刀具路径自模型及其算法,分析表明：该模型所确定的刀具路径,在相同精度下可达到最高加工效率。     

Self-generation of machining precision and its realization in lapping of super precision solid balls

This paper presents the principle of self-generation of machining precision by explaining its basic concept and five necessary conditions for forming a system with self-organization capability. A self-generation system is a kind of system with self-organization capability. The self-generation of machining precision for solid balls with super precision is emphatically explained. From the view-point of self-organization, there are three types of systems including system S1 with the self-regulation capability, S2 with the self-determination capability of goals, and S3 with the self-organization capability. Although they are all closed loop control systems, they have different constructions and functions. Necessary conditions for achieving self-generation of machining precision are given. Establishment of the system for machining solid balls with super precision is discussed. Self-generation of machining precision for solid balls with super precision on the basis of the capability of self-removal of errors is presented. Self-generation includes the ability of self-removal of errors for solid balls, convergence of self-removal of errors, self-generation of precision, and self-generating system for the given. __________ Translated from Chinese Journal of Mechanical Engineering, 2007, 43(9): 75–79 [译自 机械工程学报]     

刀片槽位置误差对可转位球头立铣刀加工精度的影响

分析球头立铣刀在刀片槽加工过程中由于各调整参数产生的误差 ,对铣刀切削刃位置的影响 ,通过计算 ,确定对铣刀切削刃位置影响最大的参数 ,建立加工刀片槽底面机床调整参数的数学模型 ,并给出由此而产生的加工表面形状误差。     

立式加工中心空间几何误差辨识解析及定位误差补偿研究

为大幅提升立式加工中心加工精度,满足当代数控机床对高精度的需求,针对立式加工中心3个运动轴,深入分析了其轴向运动空间几何误差,提出了可有效辨识运动轴轴向运动空间6项几何误差的辨识方法.建立了空间6项几何误差辨识模型,并针对关联轴联动垂直度误差进行了有效分析,建立了垂直度误差辨识解析模型.同时,针对3个独立运动轴轴向定位...     

Error analysis of a flexure hinge mechanism induced by machining imperfection

Modeling of manufacturing tolerances for machining of a monolithic flexure hinge mechanism is presented. This modeling uses a computer-based method to generate the equations of motion for the mechanism and to predict the induced motion errors for various types of machining imperfections. This paper describes the modeling and the quantitative analysis of the motion errors using a well-known simple compound linear spring as an example. Based on the simulation results of the example problem, effects of the machining imperfection types on motion errors are generalized. The simulation demonstrates that the imperfection of the center position and the size of a machined hole provide an in-plane motion error X, Y, θ_z. In addition, the machining error in the perpendicularity of the hole with respect to the plate also provides an out-of-plane parasitic error Z, θ_y, θ_y.     

Modification design method for an enveloping hourglass worm gear with consideration of machining and misalignment errors

The influences of machining and misalignment errors play a very critical role in the performance of the anti-backlash double-roller enveloping hourglass worm gear(ADEHWG).However,a corresponding efficient method for eliminating or reducing these errors on the tooth profile of the ADEHWG is seldom reported.The gear engagement equation and tooth profile equation for considering six different errors that could arise from the machining and gear misalignment are derived from the theories of differential geometry and gear meshing.Also,the tooth contact analysis(TCA) is used to systematically investigate the influence of the machining and misalignment errors on the contact curves and the tooth profile by means of numerical analysis and three-dimensional solid modeling.The research results show that vertical angular misalignment of the worm wheel(Δβ) has the strongest influences while the tooth angle error(Δα) has the weakest influences on the contact curves and the tooth profile.A novel efficient approach is proposed and used to minimize the effect of the errors in manufacturing by changing the radius of the grinding wheel and the approaching point of contact.The results from the TCA and the experiment demonstrate that this tooth profile design modification method can indeed reduce the machining and misalignment errors.This modification design method is helpful in understanding the manufacturing technology of the ADEHWG.