Abstract: To study the thermal deformation which happens on the gears of the melt gear pump during transferring the medium with high temperature and high pressure. The three dimensional model of center gear and four planet gears are built by ProE . The stable temperature field of the center gear and planet gear is established which is based on the heat transform theory. Therefrom, the ANSYS software is used to make a coupling between the temperature filed and the structure filed, and the thermal stress and the thermal deformation on the gears are studied during transferring the medium with high temperature and high pressure. The result shows that：The temperature of the surface is a little higher than the midsection’s, the decreased gradient of the temperature will increase from the top of the gear to the button in the radial direction; the temperature closed to two sides is much lower than other place in the meshing area, and the decreased gradient of the temperature in those other place is very small; the maximum thermal stress of the center gear are on the button of the meshing teeth; the maximum thermal stress of the planet gear is on the top of the meshing teeth, those two are the most dangerous positions; the thermal deformation on the planet gear is larger than on the center gear; the center gear concaves itself through outward expansion which is caused by thermal deformation, and the planet gear make itself trapezoid because of the same reason. It will result in the gears get stuck,and makes the melt gear pump fail to wok.

Key words: melt gear pump;temperature field;thermal stress;thermal deformation