A study of thermal behavior of the machine tool spindle

Abstract

The performances of high-speed machine tools depend not only on the speed, power, torque, dynamic and static stiffness, but also on the thermal behavior of the spindle. These parameters directly affect the productivity and quality of machining operations. This paper presents a 3-D finite element thermal model, which was based on the thermo mechanical bearing model and the numerical model of the spindle. Based on thermo mechanical analysis of bearings with angular contact, generated heat and thermal contact resistance are determined for each position of the ball. To provide the most accurate analysis possible in determining thermal contact resistance , bearings are divided into several zones based on the geometry of their cross-section. The aforementioned constraints have been applied to the 3-D FEM model which allowed for establishing temperature field distribution, and spindle thermal balance. In order to prove the efficacy of the proposed model, experimental measurements of spindle and bearing temperatures were done by using thermocouples and thermal imager.

An optimized thermal network model to evaluate the thermal behavior on motorized spindle considering lubricating oil and contact factors

“…A clearance fit is adopted between the bearing outer ring and housing/shell to facilitate the installation and preload. The air resistance in the gap is shown aswhere λgap means the air thermal conductivity; S is the characteristic area between the outer ring and housing/shell; and hgap refers to the thickness of gap, which can be expressed as 3,30 here hgap0 is the initial thickness of gap(m); Tring and Thou⁡sin⁡g are the outer ring and housing/shell temperatures(K), respectively; αring and αhou⁡sin⁡g are the outer ring and housing/shell thermal expansion coefficient, respectively; and rring is the outer ring radius (…”

“…where λ gap means the air thermal conductivity; S is the characteristic area between the outer ring and housing/shell; and h gap refers to the thickness of gap, which can be expressed as 3,30 h gap ¼ h gap0 À À T ring α ring À T hou sin g α hou sin g Á Á r ring (28) here h gap0 is the initial thickness of gap(m); T ring and T hou sin g are the outer ring and housing/shell temperatures(K), respectively; α ring and α hou sin g are the outer ring and housing/shell thermal expansion coefficient, respectively; and r ring is the outer ring radius (m).…”

An extended model of angular bearing - influence of fitting and pre-deformation

“…As already mentioned, most contact bearing models found in the literature do not take into consideration the dynamic effects resulting from the rotational movement of the inner ring. Exceptions include items [3], [7], [18,19].…”

“…The authors [3], [7], [18,19], while analyzing the state of bearing load resulting from the centrifugal forces of spinning balls, also took into account the deformation of the inner ring due to its rotational speed. What seems to be debatable or unacceptable is the fact that into the equations describing the displacements and deformations in the contact areas those authors inserted displacements of the inner ring, calculated according to the formula corresponding to the freely expanding gyrating ring.…”

Thermal Behavior Modeling Based on BP Neural Network in Keras Framework for Motorized Machine Tool Spindles

“…Many researchers have applied the finite element method (FEM) [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ], the finite difference method (FDM) [ 13 , 14 ], or the finite difference element method (FDEM) [ 15 , 16 , 17 ] to obtain the numerical solution of temperature field of the spindle or of the entire machine tool. On the other hand, the temperature field of the spindle can be obtained by using the thermal network [ 18 , 19 , 20 , 21 ] or bond graph method [ 22 ], whereby, thermal balance equations can be solved by the Newton–Raphson method.…”