Study On Non - Destructive Test Method For Geometric Parameters Of Large Diameter Projectile

The loading precision and the consistency of bayonet-chamber of the large caliber barrel have a great impact to the wear in the bore and firing accuracy. For that reason, the researches are carried out on field nondestructive testing method of the bayonet-chamber geometric parameter of the large caliber projectile in this dissertation. So, the research provides a new means and methods for the measurement of the consistency of the shell bayonet-chamber.On the bases of analysing the bayonet-chamber state of one type of large caliber projectile, the measuring parameters and requirements were determined. Then, a nondestructive testing method was presented for measuring the geometric parameters of projectile muzzle in firing field. The measurement principle and system composition of the measuring method were introduced. According to the coordinate transformation relation, the space geometry model of projectile muzzle parameters was established, and the calculation method is introduced.According to the testig characteristics of the bayonet-chamber geometric parameters of the large caliber barrel, The measurement system of the bayonet-chamber geometry parameters is designed. Eddy current displacement sensor and static attitude angle sensor were chosen to measure the displacement and angle based on the analyzing of the performance of a variety of displacement sensor. Testing device inside the barrel and testing device of the geometric parameters of gun’s end face were designed. The method of making and identifying mark is studied. The types and dimensions of the marking points are analyzed and determined.After pushed into a barrel, the testing device inside the barrel can traverse along the tube axial and rotate 360 degrees, and can finish the measurement of the angle and the axial position of the muzzle of the projectile at the same time.The performance of the test system was verified by experiments. In a type of barrel, the test module is on the axis of the barrel tested. By contrast with the measured value of 1/2 conical angle of the Gun-Barrel inside chamber and the theoretical one, the reliability of the measurement module was verified. The reliability of the testing module of the geometric parameters of gun’s end face was verified based on the measurement results of a certain type of projectile. By measuring the angle of the change of the angle of the projectile axis, the reliability of the measuring module was verified. On the basis of this, the experiment was carried out to measure the geometric parameters of the projectile in the true state. The stability and accuracy of the test system were verified by the analysis of the experimental results.The measuring uncertainty model for the bayonet-chamber geometric parameter of the large caliber barrel was established. The influence of machining error, installation error and sensor accuracy on the measurement uncertainty was analyzed. Then, The uncertainty of measurement of the bayonet-chamber geometric parameter of the large caliber barrel was presented, and suggestions of improvement were put forward.