Study Of Theory In Micro Heat Pipe Manufacturing Technology Of Second Vacuuming And Device Development

With the rapid development of technology, the high performance of the electronicproducts has led to the high heat flux problem. The heat sink with micro heat pipes can solvethese problems efficiently. This paper focused on micro heat pipe’s vacuum degassing process,reached the principle of the degassing, designed and manufactured the automated productionequipment, discussed the influence of the process on the performance of heat pipe withdifferent factors.(1)Automatic HP Pinching and Vaporization MachineMoving the position of the middle partition and the feeding arms, the feeding mechanismcan contain the heat pipes with different lengths between150mm to500mm. Put the heatpipes in the collection hopper, the heat pipes slop to the export along the inclined plate bygravity. The motor drives eccentric wheels to stir the heat pipes in order to fall through theexport one by one. There is a fillister in the front of the feeding arm. Heat pipe falls in thefillister, and the arms push it to the air grippers.Adjust the heating air gripper to fit different heat pipes in advance. After the arms pushthe heat pipe, two grippers clamp it at the same time. The heaters heat the bottom of the heatpipe. Rotary actuator revolves the platform with grippers, and changes the heat pipe tovertical position. The cylinder pushes the pipe through the flattening molds.After the heat pipe was raised through the molds, the thermocouple checks thetemperature of the top of heat pipe. If the measured data is higher than the setting value, thecylinder will push the mold to flatten the heat pipe in a U-shaped mouth. The cutting toolpinches the air-gather tube off. At the end the machine resets the cylinders, the grippersrelease the heat pipe.(2)The experimental research of micro heat pipe’s degassingSet up the experimental platform to simulate the working environment of heat pipe. Wecalculated the thermal resistance by the temperature difference between the evaporator sectionand condenser section of HP. We changed different factors to analyze the thermalperformances. The research have shown that the heat transfer power dropped by over80%,and the thermal resistance increased about10to100times without degassing process.Heating temperature is the greatest influence on the performance of heat pipe. Lowertemperature leads to more non-condensable gases remain in the heat pipe, the thermalperformance will not be able to reach the optimum. Higher temperature makes heat pipe lose more operating fluid so that heat pipe will easily dry out. The heating time also change theoperating fluid in the heat pipe. The longer heating time, the less operating fluid remains.Considering the production efficiency,30S is suitable for the heating time. The least influenceof the performance is the shape of necking segment. In order to reduce the cost, the neckingsegment about40mm to50mm length can meet the requirements.