整体叶轮五轴数控加工的研究

针对整体叶轮的五轴数控加工工艺,首先在CAD软件Pro/E中建立整体叶轮的三维模型;然后使用CAM软件POWERMILL对整体叶轮各个组成部分进行刀具轨迹的生成,并经过后置处理生成可用于实际机床加工的NC文件;最后基于机床仿真软件VERICUT,构建实际机床型号为DMU50V的五轴数控加工中心仿真环境,并模拟实际机床的加工过程,验证了从数控程序的生成到后置处理的正确性,减少了试切零件的误差率,检测到实际加工过程中潜在的各种风险,如机床碰撞、刀具过切或碰撞等,从而达到了优化数控加工程序、提高生产效率的目的。     

整体叶轮五轴数控加工仿真与优化

根据整体叶轮的几何特点确定叶轮五轴数控铣削加工工艺路线,并通过UG/Post Builder后置处理器生成了NC代码;利用VERICUT数控加工仿真功能建立了五轴数控加工仿真平台,实现了加工过程的仿真、优化和NC代码验证,缩短了叶轮加工的生产周期。     

数控加工软件在实践中的应用

通过一个典型零件的加工实例,介绍了在数控加工过程中使用CAD/CAM软件与数控加工仿真软件的流程,包括CAD造型、零件加工工艺分析及规划、工艺参数设置、刀具路径的计算模拟、仿真校验、后置处理生成NC程序代码、传入数控仿真软件进行仿真加工等步骤,并详细阐述了将这两种技术的优势相结合的方法与技巧。     

基于NX_CAM&VERICUT的整体叶轮数控加工与仿真方法研究

整体叶轮是影响透平机械相关产品工作性能的关键零件。现通过分析整体叶轮几何结构和加工工艺的特点,采用NX_CAM软件对其进行数控程序编制,并经后置处理生成NC代码,之后运用VERICUT软件构建全要素数控加工仿真环境并对NC代码进行机床加工模拟,以检验NC代码的准确性,有效提升了NC代码检验的效率和数控加工过程的安全性,从而缩短了生产周期,降低了成本。     

薄壁手机壳注塑模型腔CAD/CAM仿真加工与NC程序检验方法研究

为提高模具设计加工过程的柔性与高效率,解决模具仿真加工环节存在的刀具轨迹及仿真操作过程与实际加工过程存在较大差异,无法确保生成的NC代码程序在数控加工机床上安全正确的执行的问题,提出基于多种软件联合应用的模具型腔CAD/CAM仿真加工与NC代码程序检验方法,并以薄壁手机壳注塑模型腔的仿真加工与检验为例阐述其具体实现过程,仿真结果与实际加工过程高度接近。     

CAD/CAE/CAM技术在客车后围侧蒙皮拉深模具中的应用

根据客车后围侧蒙皮的特点设计三维工艺数模,利用Dynaform对其冲压成形过程进行数值模拟,分析实际冲压件的成形性,优化模具结构设计。将工艺数模信息导入MasterCAM中,设计数控铣削刀具路径,生成NC程序,并在数控仿真系统中进行仿真验证。再将NC程序输入机床控制系统,加工出模具型面,实现了覆盖件模具设计、分析和加工的一体化。     

VERICUT五轴虚拟机床模型的开发及后处理验证

VERICUT是一款专为制造业设计的CNC数控机床加工仿真和优化软件。可以在产品实际加工之前、模拟NC加工过程,以检测刀具路径中可能存在的错误,并可用于验证CAM软件和G代码输出结果,取代了传统的切削实验部件方式,优化数控程序的切削速度,获得更高效率。     

基于VERICUT的车铣复合加工技术高效应用研究

车铣复合加工中心结构复杂,运动形式多样,在进行数控加工时,NC程序编写和检测难度较大.为确保使用中机床的安全及高效,需构建其虚拟仿真加工系统,对加工过程进行仿真加工.利用VERICUT先进的仿真加工功能,以WFL M65为对象,构建虚拟仿真平台;针对机床建模中的关键点提出相应的解决方案,实现零件的仿真加工;借助优化模块对NC程序进行优化,有效地缩短了加工时间.结果表明,该虚拟仿真加工系统能可靠验证NC程序正确性,保证机床的使用安全,提高加工效率,为复杂机床高效应用提供参考.     

2×3次NURBS旋转曲面造型与数控加工仿真

基于NURBS曲面造型理论,利用CAD软件建立了NURBS曲面模型和2×3次NURBS旋转曲面模型。将曲面模型成功导入CAM软件中,进行数控加工过程仿真,生成刀具路径和NC代码。提出了根据理论刀具路径和曲率图来合理选择刀具尺寸的方法;探究了刀具路径对加工曲面精度的影响。结果表明,融入加工曲面几何信息的刀具路径,能够获得更优的加工效果。     

烟灰缸注塑模具凸模的CAM及仿真

在加工行业中,计算机辅助数控加工已经得到广泛的应用。MasterCAM针对复杂曲面,特别是由其它造型软件生成的图元文件,可以方便快捷进行零件粗加工、精加工刀具路径规划,NC代码生成以及导入机床仿真软件进行加工前模拟。针对MasterCAM导入注塑模具凸模零件刀具路径规划过程进行了深入探讨和研究。     

Enhance performance of inspection process on Coordinate Measuring Machine

Coordinate Measuring Machine (CMM) has been an important inspection tool in quality control for several years owing to its high accuracy and precision. Effectiveness of inspection plan generated by CMM greatly depends on measurement cycle time. Lesser the inspection time taken by CMM to measure a given part better will be the performance of inspection process. Therefore, it has been critical to reduce measurement time for efficient performance of inspection process. In this paper, methodologies to generate most suitable measurement path resulting into minimum inspection time has been introduced. These methodologies are based on different algorithms to reduce measurement cycle time for CMM. The different algorithms have successfully been explored and compared to show their effectiveness in minimizing inspection time for stationary CMM equipped with touch trigger probe. The proposed methodologies have also been implemented and tested on real-world mechanical part with certain number of features to demonstrate their applicability.     

Evaluation of a multi-sensor horizontal dual arm Coordinate Measuring Machine for automotive dimensional inspection

Multi-sensor coordinate measuring machines (CMM) have a potential performance advantage over existing CMM systems by offering the accuracy of a touch trigger probe with the speed of a laser scanner. Before these systems can be used, it is important that both random and systematic errors are evaluated within the context of its intended application. At present, the performance of a multi-sensor CMM, particularly of the laser scanner, has not been evaluated within an automotive environment. This study used a full-scale CNC machined physical representation of a sheet metal vehicle body to evaluate the measurement agreement and repeatability of critical surface points using a multi-sensor horizontal dual arm CMM. It was found that there were errors between CMM arms and with regard to part coordinate frame construction when using the different probing systems. However, the most significant effect upon measurement error was the spatial location of the surface feature. Therefore, for each feature on an automotive assembly, measurement agreement and repeatability has to be individually determined to access its acceptability for measurement with a laser scanner to improve CMM utilisation, or whether the accuracy of a touch trigger probe is required.     

Automated dimensional inspection planning using the combination of laser scanner and tactile probe

Combining multiple sensors on CMMs (Coordinate Measuring Machines) is useful to fulfil the increasing requirements on both complexity and accuracy in dimensional metrology. Yet, the methodology to plan measurement strategies for systems combining different types of sensors is still a major challenge. Such planning is commonly done in an interactive way. This paper presents a methodology which can create inspection plans automatically for CMM inspection combining a touch trigger probe and a laser scanner. The inspection features are specified based on the extracted geometry features and the associated PMI (Product and Manufacturing Information) items from a CAD model. A knowledge based sensor selection method is applied to choose the suited sensor for each inspection feature. For touch trigger measurements, the sampling strategy considers the measurement uncertainty calculated by simulation. A geometry-guide method is developed for collision-free probing path generation. For laser scan measurements, the required view angles and positions of the laser scanner are determined iteratively, based on which the scan path is generated automatically. The proposed methodology is tested for several cases and validated by measurement experiments. The methodology provides suited planning results and can be used for automated dimensional inspection, i.e. Computer Aided Quality Control (CAQC).     

Metrological feasibilities of CMM touch trigger probes. Part I: 3D theoretical model of probe pretravel

New 3D model of the inaccuracy of a touch trigger probe used to collect coordinates of a measured object by coordinate measuring machine (CMM) is proposed. The analysis is performed both for one and two stage types of probes. The influence of a stylus length and diameter, a spring force and direction of a contact point approach are taken into consideration. The effects of frictional interaction between the stylus ball and a measured surface are also taken into consideration. The theoretical analysis of a tough trigger probe hysteresis is presented. Finally a computer simulation of mathematical modeling in the XYZ space is shown.     

IN-PROCESS AND POST-PROCESS QUANTIFICATION OF MACHINING ACCURACY IN CIRCULAR CNC MILLING

ABSTRACT

In-process part inspection using a spindle touch probe has gained a significant importance, mainly because parts can remain on the machine without disrupting the machine setup while inspection is being conducted. This practice leads to a shorter inspection time, improved part accuracies, and reduction of scraps. Recently, intense domestic and international competition has put more importance on part quality in terms of producing parts right the first time and maintaining the consistent quality standards. A literature review revealed that a comparative analysis between in-process gauging using a touch probe and post-process inspection using a coordinate measuring machine (CMM) to ascertain part quality has not been adequately studied. Therefore, there is a need for a study to measure the characteristics of the two inspection techniques. To address the problem, cutting experiments were conducted and measurement data were analyzed using a state-of-the-art CNC machine, a CMM, a touch probe, and a high-precision ballbar system. The experimental data show that machined features and touch probe measurements are affected by the inherent shortcomings in machine tool structure, suggesting a machine tool capability analysis be undertaken in tune with the required tolerance specifications prior to machining operations, rather than solely relying on the touch probe inspection for part quality assessment.     

用触发式测头实现牙掌在线检测

在SSK—U6035五轴加工中心上，利用触发式测头（英国雷尼绍的MP10工件测头）系统和相应的检测自动编程系统实现牙掌在线定位、测量、数据处理、误差校正控制和加工一体化，大大提高了加工中心利用率和工件加工精度，降低了废品率。同时增加了该机床的功能，提高了检测自动化的程度，并且为其他类型的工件检测提供了新的方法。     

Influence of measured objects parameters on CMM touch trigger probe accuracy of probing

Influence of the measured objects parameters on coordinate measuring machine (CMM) touch trigger probe inaccuracy of probing is investigated. Factors such as material stiffness of measured workpiece, its surface shape and roughness are taken into consideration. The measuring method out off CMM, based on a rotary table and a reference axis is applied for tests. The concept is based on measurements of the distance between reference and triggering points in various directions. The reference points are established by the rotation of a precise rotary table. The statistical analysis of variance and regression is applied for data analysis.     

纳米三坐标测量机接触式测头触发控制

为高灵敏度纳米三坐标测量机(nano-CMM)接触式测头提出了一种高精度高效率的触发控制策略。该策略使用了一种自行研制的4-DVD接触式测头,工件接触测头产生的微小变形会导致测头产生灵敏度极高的触发信号。系统使用超声波马达整合不同驱动模式,实现了高速逼近和低速触发的有效结合。触发过程使用了二次触发策略,即第一次触发获得接触位置的范围,第二次触发用极低的速度,详细记录触发点附近的触发信号,并通过线性拟合的方式求得信号曲线转折点,即为触发位置。该方法解决了驱动分辨率和行程大小的矛盾。实验结果显示:该方法可以有效地避免测头系统的塑性形变,触发位置的重复性可在10 nm以内。结果表明,本文提出的nano-CMM接触式测头触发控制策略在保证精度和稳定性的前提下,表现出了良好的控制效率。     

Modelling of pretravel for touch trigger probes on indexable probe heads on coordinate measuring machines

This paper presents a pretravel model for touch trigger probes mounted on indexable probe heads, which can rotate and tilt the probe into a number of orientations for coordinate measurements on coordinate measuring machines (CMMs). Pretravel accounts for the majority of touch trigger probe errors and is caused by bending deflection of the stylus shaft. A trigger force model is derived and used to model bending deflection of the stylus shaft at the trigger instant. Only one model parameter needs to be calculated using the probe calibration data. Experimental data associated with thirteen probe orientations were used to validate the model. It is shown that the model can effectively predict pretravel distances associated with various probe approach directions. The standard deviations of prediction errors are less than 0.71 µm, indicating that the proposed model can be used to compensate for pretravels occurring in touch trigger probe applications.     

Algorithm for measuring gears implemented with general-purpose spreadsheet software

Conventional methods to verify gears are based on manual measurement instruments, such as vernier caliper gauges, gear pitch micrometers, profilometers, among others. The use of these instruments is widely described in technical literature, while in the actual industrial arena the coordinate measurement machines (CMM) are commonly used to obtain, with the appropriate software, all the parameters including the tooth profile.Commercial software for measuring gears with a CMM is usually based on continuous touch of teeth’s flanks. In the educational centres is still common to find single-point probing point to point touch machines. To transform them into continuous touch machines, new software and accessories are required and costs can be excessive for instructional purposes.This paper presents the geometrical and mathematical principles to develop a software application for measuring gears and describes its implementation using general-purpose spreadsheet software. For this purpose, the conventionally used software of the CMM is supported by a spreadsheet that calculates the probe positions and direction of measurement. The communication between the spreadsheet and the CMM software is established by ASCII files. At the end of this process, the spreadsheet displays the measurement results, thanks to its graphical and computing power, making possible to improve the learning process of students or training professionals.