Thermal error forecast and performance evaluation for an air-cooling ball screw system

In machine tools such as numerical control machines, thermal error in the ball screw induces a direct position error. A high-speed ball screw system naturally generates more heat and results in greater thermal expansion, adversely affecting the accuracy of positioning. In this paper, we discussed the placement of an air cooling system in a ball screw shaft to overcome thermal errors and achieve temperature equilibrium faster. In order to estimate the thermal error of the ball screw system and effectiveness of the air cooling system, thermal behavior models using the finite element method (FEM) and a modified lumped capacitance method (MLCM) were developed separately. This included heat generation from the main heat source of the ball screw system and other boundary conditions. The completed models were used to simulate temperature distribution, thermal deformation and air cooling performance. Comparing the experiments shows that these methods can well predict thermal behavior of the ball screw system and air cooling performance. And the positioning accuracy will significantly improve with the use of the air cooling system in the ball screw drive system.

► A center hole air cooling system was set on the ball screw system to improve the positioning error.
► In order to estimate effectiveness of the air cooling system, thermal behavior models using the FEM and MLCM were developed separately.
► A thermal behavior models using FEM and MLCM can well predict the thermal error of the ball screw system and effectiveness of the air cooling system.
► The air cooling system brings temperature equilibrium faster to the ball screw system.
► The positioning accuracy was significantly improved with the use of the air cooling system.