Analysis And Application Of Partial Annealing Thermal Field Of A286 Nail

A-286 Pull Type Blind Fastener(PTBF)is one of the typical representatives of the self-plugging rivets used in airplanes,the riveting and shaping quality of which is relied on the quality of nail set at the core element of the self-plugging rivets.While the improvement of partial structure property of the nail set through heat treatment technology is the key technology of the processing links of the nail sets.During the heating process,due to the characters of a thin wall,a little size and a narrow partial annealing range of the A-286 Pull Type Blind Fastener,the heat transfer is fast,and it is not easy to accurately control the scope of width and the change in the temperature gradient of the annealing range of the nail sets,and thus affecting the organization and distribution of hardness of the annealing range of the nail sets and deciding the shaping quality of compressing swelling of the nail sets.Under the financial aid of industrial project in the Science and Technology Department of Guizhou Province,the research on the partial annealing range of nail sets of A-286 superalloy in this topic was launched,and the detailed contents were as follows:(1)A test on the partial annealing of nail sets of A-286 superalloy was launched in the partial annealing device that was independently developed,analyzing the affection of current on temperature,the temperature distribution of partial annealed zone of nail sets and the affections from the changes in gradient on the regularities of distribution of hardness of the materials,and then the proper parameters of annealing procedures were confirmed.(2)Establish a mathematic model of the electromagnetic field and temperature field during the process of nail set partial annealing of A-286 superalloy,and the electromagnetic-thermal coupling during the heating process were described.(3)Establish a joint simulation platform with ANSOFT/Maxwell and ANSYS/Transient Thermal to conduct analog computation for the process of partial annealing of nail sets of A-286 superalloy.The affections on the magnetic field of the annealed zone,the temperature distribution regularities and size of the width of annealed zone from the parameters including the supply frequency,the current,the shape of coil cross-section,the diameter of copper pipes of coils and the inner diameter of the coil,etc.were analyzed and discussed,and the optimize parameter of partial annealing of nail sets of A-286 superalloy was obtained in combination with the orthogonal test.(4)According to the optimized technological parameter,a test was conducted by improving the partial annealing devices.The distribution of temperature during the heating process,the distribution of annealed zone of the nail set and the shaping of riveting in combination with the detection of the thermal imager showed that the result of simulation optimization of annealing process could provide important theoretical guidance for the partial annealing process of nail sets of A-286 superalloy.