Key Engineering Materials Vols. 295-296

Abstract: Ultraprecision optical components require ultra-fine smooth surface quality of sub-nanometer or sub-angstrom in Ra. To satisfy these requirements, ultraprecision on-machine measurement system is very important, by which the profile measurement and evaluation is conducted on the machine. The form accuracy is improved by compensating machining when the form accuracy is not enough. Ultraprecision on-machine measurement systems were developed for measurement with high-accuracy and high-efficiency. It was confirmed that the on-machine measurement with AFM was possible for surface roughness or complex form for local areas. In addition, a laser probe unit with a maximum resolution of 1nm, a measuring range of 10mm, a repeatability of 5.6nm and a maximum measurable angle of 60 degrees was developed. The possibility of the non-contact on-machine form measurement was confirmed for global form accuracy control.

Abstract: This article presents the development of an automatic on-line measurement system for characterizing a nanoparticle manufacturing process known as Arc Spray Nanoparticle Synthesis System (ASNSS). The ASNSS has been developed to generate metal nanoparticles and to explore the optimum system parameters for producing the desired nanopowders. Preliminary experimental results indicate that the size of nanoparticles, widely ranging from 10nm to 300nm, is significantly affected by the process parameters such as operating pressure, temperature, electrical current and type of dielectric liquid used. The on-line measurement system was developed to provide an effective multi-solution for characterizing the nanoparticle synthesis process and for monitoring the manufacturing quality of the ASNSS. Experiments were conducted to identify the optimum sampling period and volume of the particle suspension for accurate sampling and data acquisition. Experimental results revealed that a sampling duration of 20 minutes and a dielectric volume of 40 c.c. can achieve effective data representation while maximizing the sampling efficiency.

Abstract: In this paper, the main new point is the use of a non-contact combinational system with a capacitive sensor and eddy current sensors to acquire measurement signals and the use of LabVIEW software platform for real time data processing of plastic film thickness. Using a combinational measurement system to replace a traditional micrometer, the thickness of plastic film can be measured intelligently, real time, and in non-contact mode with high precision. The whole system consists of a test unit, a data acquisition unit, a motor driving unit, and a data processing unit. The test unit does measurement by means of capacitive sensor and eddy current sensors. The system is operated on the LabVIEW software platform for automatic control of the whole process. The measurement process is faster. The test results from the combinational measurement system are compared with the results from a micrometer. It shows that this measurement system has higher precision and better repeatability, reliability and feasibility.

Abstract: Linearity is a very important parameter for seamless steel pipes. A real-time and on-line visual measurement system for seamless steel pipe linearity is presented. The system consists of several structured-light visual sensors. Each sensor can achieve the coordinate of the center of partial steel pipe in its local coordinate system. Through global calibration, all coordinates measured can be transformed into an integrated coordinate system. The linearity error of steel pipe can be assessed. This method can fulfill 100% on-line and real-time linearity measurement. A pair structure-light sensor is designed to improve accuracy and a suspension-wires method for sensor calibration and global calibration is used. Through experiments, it shows that the method not only meets the need of precise calibration but also significantly improves the efficiency and feasibility.

Abstract: The objective of this work is to develop a 3D measuring system for on-line 3D measurement in industry locale. Our system is based on the depth image using a structured-light method. A generator emitting a single stripe light and a camera are used to establish a 3D vision measurement system which is also called as a subsystem. But it only can obtain the depth image of a part at the measured object section. Our system is made up of four subsystems placed symmetrically in space. The depth images obtained by the subsystems are joined to form the depth image of a full section. If the object is uniformly shafted along a fixed beeline direction, the depth image of the full object surface is achieved. The indefiniteness in the image combination criterion can be removed when using the depth image. This paper introduces the system principle and the mathematical model. The algorithm is proposed with system parameters. A prototype is developed. The system has the range of 100mm in height x 100mm in width. The length is not limited. The measuring error is less than 0.5mm in height and width and less than 0.01mm in length. The characteristics make the system suitable for on-line 3D shape measurement and non-contact measurement with high speed.

Abstract: A new in-process optical measurement method has been developed for measuring surface profiles of workpieces under the coolant condition. In this method, a laser beam passes through two additional layers. This paper presents an error analysis for the new method. The effects of key parameters on performance of the new method are examined. The theoretical analysis and experimental results show that the measurement error in this new method can be controlled within an acceptable range.

Abstract: Lateral shear interferometers have large measurement range and good anti-disturbance ability. They have similar accuracy compared with the reference based interferometers. Based on a specially designed shear generator, a new lateral shear interferometer is proposed. The new system has a complete common optical path and a simple mechanism. The optical model of the interferometer is presented and the anti-vibration characteristics are analyzed. To validate its antivibration ability for on-machine surface measurement, experimental tests have been conducted and results presented.

Abstract: The correlation method had once been considered as one of the best methods for the measurement of multiphase flow. However, if the behavior of flow does not fit the ergodic random process, the measured cross correlation plot will have a gross distortion when the different components of flow do not pervade within one another to the full extent. We measured a variety of parameters of three phase oil/water/gas flow in an oil pipeline. The change of flow pattern is so complex that the measured signals are always contaminated by stochastic noises. The weak signals are very easily covered by the noise so that it will result in great deviation. Wavelet transformation is an analytical method of both time and frequency domain. The method can achieve signal decomposition and location in time and frequency domain through adjustment and translation of scale. An LMS algorithm in wavelet transform is studied for denoising the signals based on the use of a novel smart capacitive sensor to measure three phase oil/water/gas flow in oil pipeline. The results of simulation and data processing by MATLAB reveal that wavelet analysis has better denoising effects for online measurement of crude oils with high measurement precision and a wide application range.

Abstract: Rapid progress in modern manufacturing demands for better measurement technique with on-line characteristics. This paper presents a systematic visual solution for on-line industrial 3D measurement. The solution comprises two parts, a multi-sensor visual inspecting station (MSVIS) and a digital close-range visual inspecting station (DCVIS). MSVIS is an integrated system with many sensors. It can meet the requirement of application with sparse measuring points distributed within a large volume. DCVIS only contains two digital cameras with one or more projectors. It has high relative accuracy and a small set up volume and is suitable for applications with dense measuring points. The combined use of MSVIS and DCVIS can provide a general solution for on-line industrial 3D measurement.

Abstract: This paper provides an overview of advances in the surface metrology field, concerning surface creation, measurement need, instrumentation, characterisation methods and standard development. It indicates industry requirements and further developments for micro and nano scalar surface metrology.