Papers by Author: Toshiyuki Takatsuji

Abstract: The measurement capability of the dimensional X-ray Computed Tomography (DXCT) is studied by a computer simulation and the result was compared to the observed data obtained by the measurement of calibrated gauges of same shape that consist of simple geometric forms. The simulation showed that the measurement using polychromatic x-ray is different from that of monochromatic x-ray, but the difference was far smaller than expected from the results of observed data. These results indicated that the deviation of the measured values of geometric objects was not caused by simple origin and more causes have to be taken into consideration for the actual apparatus.

Abstract: Dimensional measurement is a key process in the quality assurance of manufacturing. Not only classical one-dimensional measurement devices, several kind of three-dimensional coordinate measuring systems (CMSs) including coordinate measuring machines (CMMs) are used for dimensional measurement tasks in measurement rooms or in factory floors. For the purpose of the quality guarantee, the measurement for the validation on the products should be performed with the traceable manner. In the case of the dimensional measurement, the measurement results of the products should be stated as the corresponding values in the reference temperature, 20 °C. Therefore, at least the traceability of the length indication instruments and temperature-measuring equipment installed into the measuring device to be used should be ensured. Usually, the traceability of the instrument or equipment is ensured through the calibration on it. Now, typical CMMs in factory floor have non-calibrated temperature-measuring equipment because the equipment is hard to be detached off for the calibration, and therefore, the temperature-measuring equipment is usually left uncalibrated. Recently, a new procedure by which both the length indication instruments and temperature-measuring equipment installed into a CMM are able to be calibrated simultaneously is established. In this research, the traceable dimensional measurement using a CMM equipped with uncalibrated temperature-measuring instrument is developed by as an application of the established calibration procedure. Through the experiment, the traceable dimensional measurement using the CMM placed on the factory floor is demonstrated.

Abstract: To develop a high precision Micro Coordinate Measuring Machine (Micro-CMM), it is important to evaluate an X-Y stage on the Micro-CMM. A precision multi-probe measurement system has been designed and developed for simultaneously measuring the yaw and straightness errors of the X-Y stage. In the system, an autocollimator measures the yaw error of the stage, and two laser interferometers measure the profile of a standard mirror which is fixed on the X-Y stage. The straightness error is reconstructed by the application of simultaneous equation and least-squares methods, and the uncertainty associated with the multi-probe method is simulated. When the interval of the laser interferometers equals 10 mm, the standard deviation of multi-probe method using the high accuracy autocollimator and the laser interferometers is about 10 nm. The simulation results satisfy our purpose for the uncertainty of 50 nm, and practical considerations are discussed.

Abstract: AIST (National Institute of Advanced Industrial Science and Technology) has proposed a new calibration method of gear measuring instrument using a ball artifact consisting of two master balls and an optical flat base (DBA). We measure a circular arc instead of involute tooth form. Difference of the distance between the arc of the master ball and involute curve can be calculated theoretically. For the calculation, center distance between two balls is required and the value of measurement uncertainty is less than 0.1 'm and also should be traceable to national standard of length. This paper reports on a new method and an originally developed instrument to measure the center distance between two balls using laser interferometer. The expanded uncertainty in measurement of a center distance of 44 mm was 21 nm.

Abstract: Tooth flank form deviation of micrometers influences vibration and noise characteristics of gears and therefore strict quality control of tooth flank form is demanded. However, since gear checker is structurally-complex, it is difficult to analyze how error factors of gear checkers influence the measurement result. In this research, Virtual Gear Checker (VGC) is proposed, which is a simulation program of gear measurement considering the mechanisms and motions of gear checkers and possible error factors. The influence of the error factors on the measurement result can be clarified by VGC. VGC is also able to calculate the theoretical measurement result of non-involute helicoid artifact. It is easy for VGC to measure tooth flank form repeatedly in virtual space and therefore it can assess the uncertainty of measurement with gear checker. The uncertainty of gear measurement is calculated as an example.

Abstract: To ensure the reliability of the measurement results with optical digitizers, it is necessary that the instruments are verified under proper protocols with traceably calibrated artefacts. The requirement for test artefacts is being calibrated with small uncertainty. In addition, it is needed that the optical characteristics of the artefacts' surface are suitable for the measurement with optical sensors because optical digitizers adopt different measuring methods. In this research, the concept, structure and feature of the test artefacts are reported.

Abstract: In this research, a novel high-precision pitch artifact using balls is proposed for calibration of pitch measuring instruments. This pitch artifact is composed of the combination and the alignment of balls and cylinders on a plane. Balls, cylinders and planes are possible to be manufactured with several-ten-nanometer-order accuracy. Therefore, this artifact can accomplish high dimensional accuracy. In addition, manufacturing of this artifact is not difficult because time-consuming special process is not needed. In this report, the concept, structure and feature of this pitch artifact are proposed and theoretical analysis is carried out.

Abstract: Reversal and multiple measurement techniques have been used in dimensional metrology [1]. The reversal technique in straightness measurement is very common method. The techniques are able to reduce the errors which come from a measuring instrument and compensate the errors automatically. The techniques are available to CMM measurements. For ball-plate calibration, the reversal technique is used in National Metrology Institutes (NMIs). The technique automatically eliminates the geometrical errors of a CMM, for example, straightness, perpendicular and angle (pitch, yaw and roll). The multiple measurement technique is used for measuring symmetrical features as cylinders [2]. We tried to apply the technique for the pitch measurement of a gear. In this paper, we describe the multiple measurement techniques for coordinate metrology, especially, application to gear measurement.