Study On Engine Block Holes Position Measurement System

The position measurement of holes in the engine block top surface determines thegeneral coupling effect of the engine. All of these holes are strictly restricted by thegeometrical tolerance requirement, which determines the final engine quality. Atpresent, the block is measured mostly by the coordinate measuring machine (CMM)in the production line, and meeting the industry demands of automation, rapidity, andonline testing with the method is difficult. A new rapid solution measuring the holes inthe engine block top surface is designed, which is based on the combination ofmultiple visual sensors. The measurement system can meet the production line needsof rapidity, low cost and100%measurement.The major contributions and innovations of the dissertation are as follows:1. The engine block holes position measurement system is designed. The system isbased on the combination of multi-vision sensors and effectively improves theposition measurement efficiency of the block holes. The design of mechanicalsystem, optical imaging system and electrical control system are completed.2. The engine block vision flexible location method is proposed, which is based onthe combination of multi-vision sensors. Compare with the traditional locationmethods used in industrial field, the vision location is with higher accuracy,flexibility and better applicability.3. The position measurement model which is based on multi-scale weighting andblack-box mapping is established. The model works in the neighborhood of theholes to be measured and is applied in the background that the holes and thereference holes are not in the same plane. The model is with simple expression,high accuracy and fast operation. A more succinct position measurement modelwhich is based on feature neighborhood principle and can meet the systemaccuracy requirement is proposed.4. The system calibration method is studied. According to the position measurementmodel, the same type block whose relative spatial position parameters havealready been obtained is chosen as the calibration target. The system calibrationmethod based on the target achieves the global unity of the multiple CCD.5. The lighting, image processing and feature extraction methods of the chamfered holes are researched. The precise edge extraction algorithm is proposed. Firstly,rough edge is obtained to define the fuzzy edge region. Secondly, multi-resolutiontechnique is applied in the fuzzy region to find the optimal edge points set.Finally the precise edge of the chamfered holes is found.