| As the top product of aluminum alloy materials,high-quality and high-precision aluminum alloy sheet is an ideal lightweight material in aerospace and automotive industry.The Air Cushion Continuous Heat Treatment Production Line(ACCHTPL)has the advantages of fast heating and cooling speed,high surface quality and high temperature accuracy.So it is an essential core equipment in the production process of high-quality and high-precision aluminum alloy sheet.However,at present,both technology and equipment rely on imports,which seriously restricts the development of high-quality aluminum products in our country.Therefore,in order to improve the production technology level of aluminum alloy sheet in our country,the numerical simulation is used as an experimental means in this paper.The flow field,the air cushion dynamics,the strong convection heat transfer capacity of air cushion spray box with different structure,and the external flow field of nozzle and temperature field of aluminum plate in the process of quenching were studied,The effects of different structure and process parameters of air cushion spray box on the heat treatment process of aluminum alloy sheet were obtained.Which provides a theoretical basis for the research and development and preparation of ACCHTPL.The main work s follows:(1)Spray box with symmetrical structure,the asymmetric structure of the fan side of nozzle spray box,the rectangle side of the asymmetric structure of nozzle spray box as the calculation model,analyzed the different inlet wind speed and circulating hot air temperature on the influence law of air static pressure is strong.The study found that the different structure spray box cushion static pressure strength and force increases with the increase of inlet air cushion,with the rising of circulate hot air furnace temperature is reduced,and contrast the two types of inlet boundary conditions,inlet more obvious influence on a cushion of air static pressure is strong.The structure of the spray box has a great influence on the static pressure of the air cushion.Under the same boundary conditions,the static pressure in the air cushion area is in order from large to small:symmetrical structure spray box,asymmetrical fan-shaped side nozzle spray box,and asymmetric rectangular side nozzle spray box;(2)Combined with different inlet boundary conditions,the air cushion force of three kinds of air cushion spray box structures is calculated,and the mathematical relationship model between the air cushion force,inlet wind speed and circulating hot air temperature is obtained,which provides theoretical basis for the floating technology of air cushion heat treatment;(3)By studying the heat transfer effect of impact convection,it is found that different air cushion spray box structure has great influence on the heat transfer effect,symmetrical structure jet box has two obvious heating belts,while asymmetric structure has only one heating belt.The inlet wind speed of the spray box has a great influence on the heating rate of aluminum alloy sheet,while the circulating hot air temperature in the furnace has little influence on the heating rate of aluminum sheet.The average convective heat transfer coefficient is directly proportional to the inlet wind speed and inversely proportional to the circulating hot air temperature.Under the same inlet boundary condition,the convective heat transfer capacity of symmetrical structure is better than the convective heat transfer coefficient of asymmetric structure.(4)The simulation analysis of the quenching section of the air-cushion continuous heat treatment production line shows that the cooling curve of the impingement stagnation area changes in the same law under different nozzle outflow flow.With the increase of nozzle outflow flow,the quenching and cooling rate of aluminum plate increases,and the time for aluminum plate to reach the steady-state temperature is shorter. |
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