Optimization Model Design for Temperature Curve of Reflow Furnace

Abstract

How to adjust the temperature zone temperature and furnace speed parameters to optimize the furnace temperature curve, so as to improve the product quality is the main problem faced by the temperature curve optimization of the reflow furnace. In this paper, the heat transfer model is established by the heat convection and heat conduction equations, and the mechanism of temperature change in the welding area is analyzed. Then, by gradually determining the objective function and comprehensively establishing the optimization model according to the known conditions, the optimal parameters are solved, so as to solve the optimization problem of furnace temperature curve. According to Newton’s cooling law, specific heat theorem and Laplace equation, the temperature function of the center of the welding zone is deduced and solved, and the analytic function model of the temperature change in the center of the welding area can be obtained by synthesizing the inherent size conditions of the reflow furnace. Taking the corresponding data of experimental temperature and time as the fitting data, the undetermined parameters of the model were solved by nonlinear least square fitting method and undetermined coefficient method. The square sum of fitting residuals is 5857.7, which proves that the model has good fitting effect. Using the new experimental data to solve the model, the temperature change of the welding center at each position and time in the reflow furnace is analyzed. The temperature in the center of the welding area at the middle point of the low temperature zone 3, 6, 7 and the end of the small temperature zone 8 is 143.81°C, 181.78°C, 201.33°C, 228.97°C, respectively.