Papers by Keyword: Thermal Deformation

Abstract: This paper presents a sensitivity analysis method of temperature measuring point of the machine tool spindle based on grey system theory. The initial finite element analysis (FEA) is conducted on the spindle model to determine the temperature distribution of the spindle model and ascertain the resultant structural deformation, and eight nodes of the spindle model are selected as temperature measuring points. By means of grey system theory, temperature measuring points of machine tool spindle model are analyzed and then the effects of the different temperature measuring point on the spindle axial deformation are conducted. Finally, the validity of this sensitivity analysis method is verified by conducting the theoretical analysis and developing the linear estimate equation. The analysis results show that this sensitivity analysis method can effectively determine the thermal sensitivity of temperature measuring points, ensure the accuracy of the thermal compensation model and eliminate the coupling problems.

Abstract: With the method of finite element, the sliding friction process of pressure plate and friction disc during clutch engagement was simulated to get temperature field and thermal deformation of the pressure plate. The law of temperature distribution on the pressure plate, which achieve from the simulation is same with the one measured by thermocouple. On this basis, analyzed the influence of pressure plate’s thermal deformation to torque transmission ability of clutch and put forward the structure design method of clutch pressure plate.

Abstract: Against the problem of large machining error and low productivity of aluminum alloy spherical plain bearing, the paper is concentrated on building finite element model in MATLAB to research the radial and axial deformation law under various cutting conditions with theories of heat transfer, isoparametric element and functional variational method, providing theoretical and data support to enhance machining accuracy of spherical plain bearing outer ring.

Abstract: Against the problem of large machining error and low productivity of aluminum alloy spherical plain bearing, the paper is concentrated on building finite element model in MATLAB to research the radial and axial deformation law under various cutting conditions with theories of heat transfer, isoparametric element and functional variational method, providing theoretical and data support to enhance machining accuracy of spherical plain bearing outer ring.

Abstract: In this paper, the performance of TFC slider under second-order discontinuous boundary condition was studied. A new heat transfer coefficient under this condition according to micro/nanoheat transfer theory was deduced, and the heat transfer model on the air bearing surface was established. Using the finite element method, the differences of temperature, deformation and flying-height of TFC slider under continuous and discontinuous boundary conditions were compared and analyzed. The results show that consideration of discontinuous boundary condition is critical to the simulaiton accuracy of the heat transfer at air bearing surface.

Abstract: The dynamic and thermal characteristics of spindle assembly will affect the final machining performance of a machine tool seriously. It is of great significance to study the dynamic and thermal characteristics of the spindle assembly for improving the level of machine tool's design and manufacturing. The paper takes a high precision computer numerical control lathe as the research object. First the thermal characteristics were obtained by using finite element method. Then the laser triangle measuring instrument and the infrared thermal imager were used to measure the temperature field and thermal deformation of the spindle assembly. Finally in order to get the thermal equilibrium time and the thermal deformation data of spindle system, the wavelet toolbox was used to deal with thermal testing data. The paper's work laid a foundation for the further research on the thermal characteristics analysis and thermal error's compensation of machine tools.

Abstract: With the increasing of machine tool feed speed, a large quantity of friction heat is generated on the ball screw system and will cause the temperature rising and thermal deformation along the ball screw that reduces the machining accuracy. The heat accumulated and dissipated are calculated to load to the established model of the Y feed system on a gantry machine tool. The stable temperature field at thermal equilibrium and the unstable temperature field before thermal equilibrium or with the variation of thermal load are gotten. From thermal structure analysis, the thermal deformation is derived. The FEM model is verified by the experiments carried out under the same condition with the simulation.

Abstract: Along with increasing speed and acceleration of numerically controlled machine tools, the influence of thermal dynamics characteristics on operating accuracy becomes more and more important. Improvement of thermal dynamics characteristics has turned out to be one of the crucial problems to develop machine tool of high performance. The positioning error of a feed drive system, mostly caused by the thermal deformation of a ball screw shaft, can directly affect the working accuracy of the machine tool. In this study, we applied the computational approach using the finite element method (FEM) to simulate the thermal expansion process for estimating the deformation of the ball screw system. In the numerical analysis, the deformation of the ball screw shaft and nut was modeled via a linear elasticity approach along with the assumption that the material was elastic, homogeneous, and isotropic. To model the reciprocating motions of the nut at a speed of 60m/min respecting to the screw shaft, we utilized the three-dimensional unsteady heat conduction equation with the frictional heat from the sources of the ball screw shaft, nut and bearings to calculate the temperature distributions for determining the temperature rises and axial thermal deformations in a ball screw shaft under operating situations. Simulations were conducted to explore the connection between the temperature increase of nut and the thermal deformation of the ball screw drive system, revealing the need of a compensation scheme for thermal error to improve the operating accuracy of machine tools.

Abstract: The spindle box is the key part of the machine, and the distribution of the temperature field and the thermal deformation will directly affect the machining precision under multiple heat sources. Taking the spindle box of the CX056 nuclear power rotor wheel groove milling machine as research object, the heat sources and boundary conditions were calculated, and the temperature field and the thermal deformation were established under action of different ambient temperature, using finite element method. Finally, the effects on the front end of the spindle were analyzed under different environment. The analysis result shows that the environmental temperature had an obviously effect on thermal deformation of the spindle box, and controlling environmental temperature reasonably can reduce the thermal deformation and improve the machining accuracy of machine tool.

Abstract: Taking XK5034 vertical milling machine as the research object, its thermal characteristic's finite element analysis has been carried out through the ANSYS. The front-end of the spindle mainly affects the machining accuracy of machine tool, so on the basis of the temperature field analysis, its thermal deformation was analyzed under different environment temperature, and the change rules between environment temperature and thermal deformation of the front of the spindle was also acquired. The results show that the influence of machine tool thermal deformation under different temperature is obvious.