Study On Sealed Automatic Soldering System Construction For Large Cavity Components And Welding Quality

Sealing soldering for large cavity components is mainly done by manual operation, and the way of welding is soft soldering. The welding process is complicated, the welding quality is not stable, the welding efficiency is low and the rejection rate is high. With the development of automatic welding technology, the realization of welding process automation for large cavity components will become an inevitable trend.The present thesis is to study the automatic system of the sealing soldering for large cavity components which are used to internally install multi-function electronic devices and improve the welding quality. Using the HP20D industrial robot as the platform, the end executor and fixture positioning machine are designed. The effects of sealing soldering process on welding quality are studied. The high quality soldering technology is realized.The joint connecting rod coordinate system of the robot is established, the D-H parameters of the robot are obtained. The kinematics analysis of the robot is carried out. The spatial relationship between the robot’s end-position and the six-joint rotating angle are determined. The kinematics positive solution and inverse solution are computed. The kinematics properties are simulated. The control function of upper computer (PC) is secondarily developed. The motion control interface of the robot is designed. The interpolation and velocity of the robot’s end executor are controlled by the upper computer (PC). The function of uploading and downloading welding procedures are realized.The end executor is designed and composed of the whole structure, the heat device and the control system of temperature and power. The reliable connection between the end executor and the robot, the safety of the heat transfer, the controllable power and temperature are realized and assured. The fixture positioning machine is designed. The statics and modal analysis of fixture positioning machine are studied. The results show that the main deformation part is the rotary support frame which can be ignored due to the tiny deformation and the natural frequency of the fixture positioning machine is mainly distributed from 50Hz to 230Hz.The finite element model of welding temperature field is established. According to the simulation results, the welding quality is improved when the welding speed is chosen between lmm/s and 2mm/s. The temperature of each point on the heat source along the welding direction can reach the peak value and then fall down sharply. The peak temperatures are the same as or higher than the melting point of the material under the condition of quasi steady state. The trends of temperature variation on each point of the soldering on the cross section are similar. The higher the welding speed, the smaller the welding temperature area and the welding temperature are.The effects of the welding angle, the boundary heat source, the welding speed, the welding times and the welding temperature on the welding quality are studied. The results show that the welding quality is better under such conditions as the welding head angle of 60°, the preheated treatment of the component by using an air heater, the welding speed from 1mm/s to 2mm/s, the option of the twice welding times, and the welding temperature from 350℃ to 450℃.