No abstract

To guarantee tooth form accuracy of gear8， three strong demands are now subjected ： ( a )tQ use production gear size artifact for checker calibration ， ( b)to clarify the uncertainty of measured results and( c )to give traceability to the results ． For involute checker calibration ， involute artifact has been widely used ， because of its friend 置 iness at usage ． But， espec 主 ally for item ( b)and ( c )above ， 洫 volute artifact has big difficulty ， Japan has propo8ed Double BaU Artifact to the ISO TC60 WG2 for involute checker calibratiQn to solve these problems and to achieve far more accurate calibra − tion work ． The development of JIS Qn this matter 重 s now on the wa ｝ t This report introduces the ou もline of the work ．

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.

Vibration of gears is a serious problem in mechanical devices. The characteristics of these vibrations are strongly affected by tooth flank form deviation of micrometer or submicrometer order. The quality of manufactured gears is controlled by a gear-measuring instrument. The accuracy of the profile measurement by such an instrument is evaluated using a master gear or an involute artifact. However, it is difficult to manufacture gears with high accuracy because the involute is a complicated geometrical form. To solve this problem, the double ball artifact (DBA) has been proposed as a means to evaluate the profile measurement accuracy. The application of the DBA requires a DBA design method so that the DBA can be applied to a wide variety of gear dimensions in the industrial field and can realize high-precision evaluation. In the present study, a design method is proposed for the DBA, and the dimensions, tolerance, and material of the DBA are determined. A DBA is designed and manufactured according to the proposed design method and the effectiveness of the manufactured DBA is verified experimentally using a gear-measuring instrument.

Assessment of measurement performance of gear measuring instrument is not easy task since a traceable master piece with sufficient accuracy has not been available. We propose a new artifact named Double Ball Artifact (DBA) which consists of a base plate and two balls. It has advantages of inexpensive, accurate, and calibrated with traceability. The examples of measurements by gear checkers and CMM will be presented to confirm the usefulness and validity of the artifact.