螺纹量规的数字化检测方法

螺纹量规是判定螺纹紧固件合格与否的重要量具,其几何参数的精确测量具有重要意义。利用螺纹综合测量仪完成了螺纹量规的数字化测量试验,分析得出该方法的测量结果准确,精度可靠。同时对螺纹综合测量仪测量中径的不确定度进行了评定,为螺纹量规的测量质量提供了参考依据。     

Calibration and uncertainty evaluation of single pitch deviation by multiple-measurement technique

Gears are key elements of power transmission systems, and the inspection of their pitch deviation is one of the most important tests on gears. The specifications of gears are assessed using gear measuring instruments (GMIs) or coordinate measuring machines (CMMs), and the results of the measurements must be validated under an appropriate traceability system. In the traceability system, calibrated gauges whose measuring uncertainties are estimated are necessary. In the case of pitch deviation measurement, special artefacts or gears manufactured with high dimensional accuracy are used as reference gauges. In this paper, authors propose calibration and uncertainty evaluation methods for the single pitch deviation of gears measured using CMMs. First, the evaluation of single pitch deviation using a multiple-measurement technique and the estimation of its uncertainty based on the analysis of variance are formulated. Second, a technique for reducing the measurement trials based on the symmetry of the measurement is discussed. Finally, the proposed calibration method is validated through experiments.     

In-situ water level measurement using NIR-imaging video camera

Water level is a critical component for observation and management of water resources. Since video surveillance is becoming a standard configuration of gauging stations, more attentions have been paid on the image-based water level measurement techniques in recent years. Instead of human eyes, images of staff gauge can be captured by a camera and automatically processed to detect the readings of water line. However, it is quite unreliable to identify the readings on staff gauges due to low imaging resolution, tilt viewing angle and complex illumination in field conditions. For that reason, most of the existing methods failed to make effective automatic measurements in practice. To resolve difficulties of poor visibility, image distortions and ambient noises in in-situ water level measurement with standard bicolor staff gauges, an all-weather, real-time and automatic flow measurement system using single near infrared (NIR)-imaging video camera is developed. Lab and in-situ experiments demonstrate that NIR-imaging is efficient to enhance image contrast and suppress reflection noises on the water surface, which successfully overcomes the limitation of water line detection with current visible light (VIS)-imaging systems in clear water and low velocity conditions. The proposed water level conversion method is based on image ortho-rectification. It requires no on-site calibration by utilizing natural corresponding points to build the perspective transformation between the staff gauge Region of Interest (ROI) and an orthographic template image. The measurement resolution of water level (1 mm) is controlled by the physical resolution (1 mm/pixel) of the template. The proposed water line detection approach is integrated by a series of algorithms: the Order-Statistic Filtering for adaptive thresholding, the Morphological Opening Operation for local noise suppression, the Multi-points Continuity Criterion for water line locating and the Median Filtering for random noise elimination. It overcomes the deficiency of traditional Otsu method for images with uneven illumination. The reliability of system under various weather and illumination conditions is proved with water level accuracy up to 1 cm and Effective Data Ratios up to 95%.     

Dimensional management for aerospace assemblies: framework implementation with case-based scenarios for simulation and measurement of in-process assembly variations

Tolerances within an assembly are defined during the setting of engineering specifications in the design phase. However, during assembly process execution, certain assembly variations arise from the individual components, manufacturing imperfections, material compliance, the means by which they are fastened and the assembly sequence used. The implementation work reported in this article utilises in-process assembly measurement information for predicting dimensional variation of the aero structure assembly process. A framework is exploited in the case study for predicting the dimensional influence of (1) designed tolerances, (2) designed assembly processes and (3) component and sub-assembly level measurement data for revising the assembly sequence if any concessions were issued on manufactured components. Considerable learnings are achieved while managing dimensional variation of in-process aerospace assembly structure. Dimensional variation simulation is found to be overestimating variation spread even after considering compliance of non-rigid components. Thus, in-process measurement data (component and sub-assembly level) has to be integrated in the variation analysis in order to reduce variation spectrum. Case-based scenarios are discussed where design and measurement data can be utilised for estimating dimensional variation of the in-process assembly.     

Feasibility of dimensional gauges made of plastic used for acceptance tests of coordinate measuring systems

Dimensional X-ray computed tomography systems (DXCT) having the capability of measuring sizes and geometrical features are paid attention as a new type of coordinate measuring systems (CMS). A gauge used for verifying the measurement performance of DXCT is demanded for made of the material having low X-ray attenuation coefficient. In this study, the plastic is proposed to be used as a material of the gauge and the suitability of that is investigated. The observation of long-term dimensional stability shows Poly Phenylene Sulfide (PPS) is the most stable material in the observed plastics. The evaluation of actual CTE of plastic and of calibration uncertainty is demonstrated. The test uncertainty of the performance test of a coordinate measuring system including DXCT was estimated. The estimated uncertainty leads the guideline of conditions to be considered when the performance of DXCT is evaluated using the gauges.     

Analysis, characterization and accuracy improvement of optical coordinate measurement systems for car body assembly quality control

Many car manufacturers are installing in-line car body measurement systems in order to achieve dimensional quality control of the whole production. The geometrical tolerances required by this product are narrowing increasingly; consequently, it is necessary to design these systems to calculate corrections and uncertainties as accurately as possible. This paper studies the error sources and analyzes their influence on measurement results by means of simulation and experimental tests during a nine-month study. The final goal of this work is to describe an optimization procedure for the accuracy improvement of the system. This is achieved mainly by applying a number of corrections designed to minimize the errors detected during the practical tests, and by means of algorithms to eliminate dispersions caused by a lack of stability in the positioning of the car body in the optical measurement system, or by temperature variations to reduce the final error.     

Review of Electronic Speckle Pattern Interferometry （ESPI） for Three Dimensional Displacement Measurement

Three dimensional（3D） displacements, which can be translated further into 3D strain, are key parameters tor design, manufacturing and quality control. Using different optical setups, phase-shift methods, and algorithms, several different 3D electronic speckle pattern interferometry（ESPl） systems for displacement and strain measurements have been achieved and commercialized. This paper provides a review of the recent developments in ESPI systems for 3D displacement and strain measurement. After an overview of the fundamentals of ESP! theory, temporal phase-shift, and spatial phase-shift techniques, 3D deformation measurements by the temporal phase-shift ESPI system, which is suited well for static measurement, and by the spatial phase-shift ESPI system, which is particularly useful for dynamic measurement, are discussed. For each method, the basic theory, a brief derivation and different optical layouts are presented. The state of art application, potential and limitation of the ESPI systems are shown and demonstrated.     

The design of terrestrial and aquatic micro-environmental chambers for use in low powered video,cine and photomicrography

The observation, recording and control of active biological specimens is time consuming and not easily achieved in low powered microscopy. To overcome this, perspex micro-environmental chambers have been designed to enable the control of temperature, air and water flow, illumination and image format to suit individual species and specimens. When the chambers are in use, they are ‘closed’ systems and can be maintained for long periods; up to several days if required. Two separate systems have been developed (aquatic and terrestrial) and both allow the use of integrated illuminated systems. The chambers are made from perspex and the viewing area, the ‘windows’, are made from high quality optical glass. These chambers have been designed to match television format (3:4) and retain the specimen and ensure it remains in the field of view during a video, cine or photomicrographic recording session. The chambers can be used in vertical or horizontal observation systems and are attached to the microscope focusing substage. It also allows the use of incident and transmitted illumination systems including bright field, with or without polarized light observations, and dark field. The assembly of the chambers appears complex but is easily achieved.     

基本磁性参数综合测试系统

将振动样品磁强计，磁转矩测试仪，磁电阻效应测试仪的资源重新配置，借助轨道运载可移动的电磁铁将3台仪器平台有机地组合在一起，并设计一个系统能够将各自的应用软件集成在一个软件环境下，实现资源的共享、数据的交流、数据的综合分析与运用，提高设备的利用率。结果表明：在硬件上节省了2台电磁铁、2套计算机和接口电路等；在软件上，统一了数据在一个界面下的处理和存储格式。这是一种典型的以时间换取资源的合理配置。     

Design and testing of an innovative measurement device for tyre-road contact forces

The measurement of tyre-road contact forces is the first step towards the development of new control systems for improving vehicle safety and performances. Tyre-road contact forces measurement systems are very expensive and significantly modify the unsprung masses of the vehicle as well as the rotational inertia of the tyres. Thus, vehicle dynamics results are significantly affected. As a consequence, the measured contact forces do not correspond to the contact forces under real working conditions. A new low-cost tyre-road contact forces measurement system is proposed in this paper that can be applied to passenger cars. Its working principle is based on the measurement of three deformations of the wheel rim through strain gauges. The tyre-rim assembly is thus turned into a sensor for tyre-road contact forces. The influence of the strain gauges position onto the measurement results has been assessed through finite element simulations and experimental tests. It has been proven that, for a large variety of rims, the strain gauge position that leads to high signal-to-noise ratios is almost the same. A dynamic calibration procedure has been developed in order to allow the reconstruction of contact force and torque components once per wheel turn. The capability of the developed device to correctly estimate tyre-road contact forces has been assessed, in a first stage, through indoor laboratory experimental test on an MTS Flat-Trac^® testing machine. Results show that the implemented measuring system allows to reconstruct contact forces once per wheel turn with a precision that is comparable to that of existing high-cost measurement systems. Subsequently, outdoor tests with a vehicle having all four wheels equipped with the developed measuring device have also been performed. Reliability of the measurements provided by the developed sensor has been assessed by comparing the global measured longitudinal/lateral forces and the product of the measured longitudinal/lateral accelerations times the vehicle mass. A good agreement has been found during all the performed manoeuvres.     

A distortion corrected single camera-based weight estimation technique for industrial objects

This paper describes a unique single camera-based dimensional measurement with a self-calibration method of image-based measurement. The system has been designed and implemented in one of the integrated steel plants in India. The purpose of the system is to obtain the frontal cross-sectional area of an ingot irrespective of its distance from the camera head. Automatic calibration is achieved by attaching a magnetic template of known area. This self-calibrating system is further refined to correct for the various distortions arising out of lens characteristics. The results obtained through field trials have been reported and found to be quite encouraging.     

New criterion for evaluating the aptitude of measurement systems in process capability determination

In practice, carrying out statistical process control of manufacturing processes requires the use of measurement systems. These systems are not totally reliable because they are subject to inherent variability. This paper investigates the influence of measurement uncertainty on the analysis of manufacturing process capability. A new methodology is described that helps overcome the effect of measurement uncertainty in order to obtain a more accurate assessment of the capability of the production processes. This methodology presents a solution that ensures the metrological confirmation of the measurement processes, and it was developed for manufacturing processes centred at a nominal value and for off-centred processes. Moreover, an improved capability index integrated into the statistical process control is proposed for evaluating measurement systems. The index helps identify manufacturing process quality risks associated with uncertainty in measurement systems.     

非球面补偿板三维面形检测方法的研究

本文对准直激光束检测非球面方法进行了研究。它不用接触被检件表面,同时也无须处理干涉条纹。测量时只要保证激光细束保持一致的入射方向扫描被检表面,用CCD光电探测器检出面形的斜率变化,而后在扫描范围内积分便能获得面形高度。本文以测量光学系统中用于波面补偿目的的旋转对称镜面为例对测量系统进行分析。该系统不仅可以进行一维测量,通过转台旋转亦可进行二维测量,通过面形重构获得三维的被测体面形。给出了三维面形重构方法,并编制数据处理软件,可以把测量数据处理成高度曲线或三维面形。     

非球面补偿板三维面形检测方法的研究

本文对准直激光束检测非球面方法进行了研究。它不用接触被检件表面,同时也无须处理干涉条纹。测量时只要保证激光细束保持一致的入射方向扫描被检表面,用CCD光电探测器检出面形的斜率变化,而后在扫描范围内积分便能获得面形高度。本文以测量光学系统中用于波面补偿目的的旋转对称镜面为例对测量系统进行分析。该系统不仅可以进行一维测量,通过转台旋转亦可进行二维测量,通过面形重构获得三维的被测体面形。给出了三维面形重构方法,并编制数据处理软件,可以把测量数据处理成高度曲线或三维面形。     

A computer simulation platform for the estimation of measurement uncertainties in dimensional X-ray computed tomography

The knowledge of measurement uncertainty is of great importance in conformance testing in production. The tolerance limit for production must be reduced by the amounts of measurement uncertainty to ensure that the parts are in fact within the tolerance. Over the last 5 years, industrial X-ray computed tomography (CT) has become an important technology for dimensional quality control. In this paper a computer simulation platform is presented which is able to investigate error sources in dimensional CT measurements. The typical workflow in industrial CT metrology is described and methods for estimating measurement uncertainties are briefly discussed. As we will show, the developed virtual CT (VCT) simulator can be adapted to various scanner systems, providing realistic CT data. Using the Monte Carlo method (MCM), measurement uncertainties for a given measuring task can be estimated, taking into account the main error sources for the measurement. This method has the potential to deal with all kinds of systematic and random errors that influence a dimensional CT measurement. A case study demonstrates the practical application of the VCT simulator using numerically generated CT data and statistical evaluation methods.     

Traceability to SI units for vacuum measurement in industrial applications

In the context of international standards like the ISO 9000 series or ISO 17025 the traceability of measurement instruments of physical units in industrial processes gained more importance in the last two decades, so to say also for vacuum measurement. Traceable calibrations of vacuum gauges ensure agreement with the SI units. For this purpose vacuum primary standards are needed. The international system of metrology ensures that the vacuum primary standards registered in the system are equivalent and fulfill their specifications. Secondary and reference standards are used to disseminate the pressure scale in vacuum to calibration laboratories, to the manufacturers of gauges, and finally to industrial processes or to research facilities. Suitable vacuum gauges for this purpose including their expected measurement uncertainties will be described. Notes for the measurement uncertainties at the place of the end user will be given.     

Design for automating the inspection of manufacturing parts

The integration of quality into management of advanced manufacturing systems has not typically included automated approaches. With the advent of automated inspection and quality tools such as coordinate measuring machines and other dimensional measuring equipment, the linkage with integrated manufacturing systems seems natural. This paper shows the functional relationship of computer aided process planning to automated inspection process planning. The series of functional activities within each of these frameworks are mapped in this paper. The operational environment to include computer aided quality control in an integrated manufacturing system is also defined.     

Application of microcomputer for assessing the probe lobing error and geometric errors of CMMs using commercial ring gauges

Performance verification and frequent reverification of working accuracy of coordinate measuring machines are currently acknowledged as essential operational processes. In this paper, an efficient microcomputer based method has been proposed for the accuracy assessment of the CMMs of CNC type based on the probing of commercially available ring gauges. The geometric inaccuracy data of the ring gauges are measured, stored, and thus can be used as a transfer standard. A computer module for measurement-path generation has been developed, with which automatic CNC measurement codes can be generated for specific CMMs. The ring gauges are measured on the CMMs, and the measured data are feedback to the PC. For the error analysis, a new error analysis module has been developed for performance checking of a measurement probe, where the direction-dependent probe lobing error can be successfully evaluated. A least-squares-based approach has been implemented, with which the scale errors and the squareness error can be evaluated simultaneously in the local measurement position. The advantages of the proposed method are:

1. The rapid assessment for the probe lobing error.
2. Simultaneous evaluation of the scale errors and the squareness error.
3. Highly integrated approach for the measurement-error evaluation processes, which are implemented via a PC.

Practical CMMs have been chosen and the accuracy assessment is performed, demonstrating the high efficiency of the developed system. The developed method can be applied to performance verification or day-to-day reverification of CMMs of CNC type.     

Thermo-mechanical analysis in pulsed laser cladding of WC powder on Inconel 718

The increasing interest towards intelligent systems has led to a demand for the development of zero-defect strategies, with a paradigm shift from off-line and dedicated to in-line metrology with integrated robotic systems. However, a major barrier preventing the systematic uptake of in-line metrology is the lack of evaluation of system capability in terms of accuracy, repeatability and measurement time, when compared to the well-established coordinate measuring machine (CMM). In this study, a robotic Laser Radar (LR) solution is assessed in the context of automotive dimensional inspection of Body-In-White (BIW) applications. The objective is both to understand the effect of robot re-positioning error on measurement accuracy and repeatability and to compare measurement results against a CMM. Eighty-one surface points, six edge points, twenty-five holes and sixteen slots were selected from an industry standard measurement plan. Whilst LR exhibits a lower measurement accuracy than twin-column CMM, its repeatability is well within the specification limits for body shell quality inspection. Therefore, as a real-time in-line metrology tool, it is a genuine prospect to exploit. This research makes a significant contribution toward in-line metrology for dimensional inspection, for automotive application, for rapid detection and for correction of assembly defects in real time, with subsequent reduction of scrap and number of repairs/re-works.     

NURBS curve and surface fitting for reverse engineering

Reverse engineering is an approach for constructing a computer-aided design (CAD) model from a physical part through dimensional measurement and surface modelling. This paper presents alternatives for reverse engineering of free-form parts using Non-Uniform Rational B-Spline (NURBS) surfaces. A two-step linear approach is employed for fitting NURBS curves and surfaces using the measured points. During the first step, the weights of the control points are identified from a homogeneous system using symmetric eigenvalue decomposition. The control points are further processed in a way similar to B-spline curve and surface fitting. Some examples are presented to illustrate both the steps of reverse engineering and the process of NURBS curve and surface fitting.