World Congress Fundamental and Applied Metrology September 6 − 11 , 2009 , Lisbon , Portugal ADVANCED CALIBRATION METHOD FOR PITCH ARTIFACT
Abstract − The pitch measuring accuracy for gear measuring instruments (GMIs) is evaluated by measuring a calibrated artifact. We proposed a novel artifact which called multiball artifact (MBA). The MBA is composed of the pitch balls assumed to gear teeth and the reference axis assumed to a center axis of gear. The MBA can be calibrated more accurate than a conventional pitch artifact. When the MBA is calibrated, it is important to eliminate an error of measuring instrument; therefore we calibrate the MBA adapting the multiple-orientation technique. In the multipleorientation technique, the MBA is set up in difference orientations around the reference axis and the measurement error is eliminates by averaging the measurement value for all orientations. There are, however, Fourier components of the measurement error that can not be eliminated depending on the total number of orientations. In this paper, we propose the advanced calibration method; the error separation method for the multiple-orientation technique is improved and the total number of orientations can be reduced. The superiority of the proposed method is clarified from the calibration results using the MBA.
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.
斜入射ホログラフィ干渉による機械部品の面形状・精度の測定 : 第1報, 測定対象面の撮影像と実際の被測定面上の位置対応
In interferometry measurement using laser holography, it is not easy to find a definite relation between the measured image pattern and the topography of the actual surface. The main reason is that each of the measuring object, measurig apparatus, electronic data processor and CRT display has its own coordinate system, and the transformig or mapping relation between them is obscure. In this report, measured image of some test pieces with plane and cylindrical surfaces were compared with their simulated figure. Subsequently, tooth flank of a gear, which is a three-dimensional curved suface in which high accuracy in form is required, was chosen as the object of measurement. To obtain the relation between each coordinate system of a measuring object, of optical parts in the measuring appartus and of the image on a CRT, a method is proposed which requires the simulated contour of the diffracted figure of the objective curved surface to be measured corresponding to and fitting the actually measured and observed image pattern on the CRT. The experimental and simulated results indicate that the pixel position of the image on the CRT can correspond to the coordinate value of the tooth flank, and that the transformation of the measured image on the CRT to the error surface of tooth flank defined on the plane of action of the gear, i. e., to the tooth form chart and to the tooth trace form chart, is possible.