| At present,with the rapid development of mechanical manufacturing industries such as aerospace,automobile manufacturing,energy and chemical industry,and weapons and equipment,the design and research and development of various parts with special functions also require deep holes with high aspect ratio and high straightness.Therefore,it is of practical significance to further study the straightness error of deep hole machining with the requirements of high precision and high aspect ratio.The uncertainty and complexity of deep hole machining process not only make the phenomenon of hole axis deflection become a common problem in this field,but also make the detection of deep hole axis straightness error become a major technical problem.In order to improve the detection accuracy of straightness error of deep hole axis,based on the principle of ultrasonic thickness measurement and the theoretical basis of cuckoo algorithm optimization,this paper establishes a straightness detection model of ultrasonic thickness measurement for deep hole workpieces,and improves the accuracy of straightness error detection of deep hole axis through later algorithm optimization processing.The main work is as follows:(1)The model of ultrasonic testing is established,and a scheme for measuring the straightness of deep hole axis based on ultrasonic thickness gauge is proposed.Mark the workpiece of the deep hole to be measured with multiple experimental sections,and measure the wall thickness of the workpiece of the deep hole at multiple angles of the experimental section through the ultrasonic thickness gauge.With the center of the bottom surface of the deep hole workpiece as the origin,and the theoretical axis of the center as the Z axis,a space rectangular coordinate system is established.The wall thickness data is converted into the coordinates of the circumference space points through mathematical methods.Through the principle of three-point circle determination,a center point can be obtained for every three points,and the space coordinate data of the center point cloud of each test circle can be recorded.(2)The test results are checked and analyzed by the three coordinate method: the straightness error can be evaluated based on the actual axis of the deep hole.The accuracy of straightness error can be accurate to three decimal places by using ultrasonic testing method,while the accuracy of three coordinate testing method can be accurate to four decimal places,and the measurement is more intuitive and accurate.Therefore,in this test,the first and last ends of the deep hole workpiece are cut off,the point coordinates are obtained by using the three coordinate method,and the center point of the hole diameter is calculated.The error range is calculated by comparing with the center point cloud data obtained by the ultrasonic thickness gauge.(3)a more accurate error evaluation method of SA-CS algorithm is proposed.On the basis of the actual axes of deep and small holes measured by three-coordinate machine,combined with three kinds of straightness evaluation methods,which are two-endpoint connecting line method,least square connecting line method and minimum enveloping cylinder method,with the help of MATLAB software,thus,the axial straightness errors of deep and small holes under different evaluation methods are solved.Based on the SA-CS algorithm,Levis’ s good ability of global optimization in flight,selected good points to solve the center of circle coordinates of each section,and reduced the measurement error of the deep hole axis straightness,compared with the above three algorithms,the SA-CS algorithm is proved to be the least error.(4)the error value of the center point coordinate of each section of the deep hole based on the three-coordinate detection result of the ultrasonic detection is brought into the CS algorithm formula,and the algorithm formula is modified according to the error value,the same error precision as the straightness measured by the three-coordinate measuring method can be obtained. |
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