Research On Measurement Method And Experiments For High Temperature Parts

Huge rotor of nuclear power system, large crankshaft of marine diesel engine and special deck of submarine are key parts in huge electromechanical equipments. Measuring geometric parameters of those parts accurately and timely during its free forging can increase material utilization ratio, save energy, improve manufacturing quality and production efficiency, which has an important practical significance. While, many factory are still using manual contact measurement method, which has disadvantages of large measuring error, long-time consuming. This results in increasing process allowance and hinders improving product efficiency. This paper aims at on-line measuring for parts, analyzes issues of three-dimensional measurement for parts and image acquisition for high temperature parts. The purpose of this paper is to provide a new method for resolving the key problems mentioned above.According to existing problems of large error by manual contact measurement and bad environment, a method of stereo vision is proposed. Stereo vision method is qualified for on-line measurement of parts for advantages of non-contact, plenty measurement information and three-dimensional measurement. For strong radiation created by high temperature parts, which is in camera's photoreception range has influence to image, spectra selectivity image acquisition method that avoid using strong radiation created by high temperature parts to get image directly, while use its reflection in a certain narrow band in weak radiation band, combining with illumination light source to get image is put forward. Image effect is proved closing to image in room temperature through testing. The method not only can serve for following measurement, but also can be used as observational means for surface defect detection of high temperature parts.A measuring system consist of illumination light source, CCD cameras, band pass filters, non-contact measurement instrument and work station is constructed based on measurement method mentioned above. On the basis of sufficient analysis for various camera calibration methods, CCD camera is calibrated using calibration method based on two-dimensional calibration board, the calibration result is verified through practical measuring experiment. Experimental result demonstrates that the proposed geometric parameter measuring method and calibration method are qualified for experiment of measuring high temperature parts.