Papers by Keyword: Thermal Error

Abstract: Thermal deformations of machine tool are among the most significant error source of machining errors. Most of current thermal error modeling researches is about 3-axies machine tool, highly reliant on collected date, which could not predict thermal errors in design stage. In This paper, in order to estimate the thermal error of a 4-axise horizontal machining center. A thermal error prediction method in machine tool design stage is proposed. Thermal errors in workspace in different working condition are illustrated through numerical simulation and volumetric error model. Verification experiments shows the outcomes of this prediction method are basically correct.

Abstract: This paper investigates the software error compensation in CNC machining centers On-line inspecting system. Based on Windows 2000 operating system, compensation software is developed. It investigates modeling errors. The software can compensate probe errors, thermal and geometric errors. The software system is tested on MAKINO upright CNC machining centers, and the results verify the effectiveness of the method.

Abstract: Heat resulting from motors, moved contacts as well as cutting processes, causes time-dependent deformation of machine structures that reduces the precision of machine tools. For design optimization and especially for correction of thermal induced displacements, it is necessary to have compact models, which allow fast simulation of the thermo-elastic behaviour of the entire moving machine tool during the process. This paper presents an innovative simulation technology that permits, starting from CAD geometry through FE modelling, to come to a time-saving thermo-elastic calculation model of entire moved machine tools. Thereby, calculated temperature and deformation fields are of high geometrical resolution. Results and potentials of the new approach are demonstrated on example of a Hexapod machine tool.

Abstract: This paper gives a description of the challenges in the development of a generalized approach for the structure model based correction of thermoelastic errors of machine tools. The correction approach can be divided in modules. The challenges are described on the requirements of the modules.

Abstract: The measures taken to improve the thermal behaviour of machine tools are based on thermal models. The models are applied to support the design process and to correct the machine tool operation in a control-based way. Especially the models for correction purposes include uncertain parameters that cannot be estimated with sufficient accuracy. Thus these parameters have to be adjusted by means of measurements. During the adjustment process, a broad diversity of machine behaviour and model characteristics has to be taken in to account. Therefore, substantial time, effort and expert knowledge are required. To identify the key expenses, a generalized and systematic analysis of the adjustment process was carried out. First, the typical design of the models, the parameters of the sub models and the current adjustment procedure were investigated. Based on the results of the analysis, support requirements were identified. Afterwards first methods and software tools for efficient support were developed. This strategy is demonstrated using the example of a hexapod strut model.

Abstract: Thermal models of machine tools contain parameters whose values have a high degree of uncertainty and which can limit the accuracy of the model beyond applicability. Thus, the parameters have to be adjusted by means of measurements. At present, substantial time, effort, and expensive measurement equipment are required for adjustment, as well as in-depth expertise. For these reasons, we have studied the development of methods providing rapid, comprehensive, and low-cost adjustment. This objective can especially be achieved by methods that support the planning stage of the model-adjustment procedure. The paper demonstrates this based on methods for model and behaviour visualisation.

Abstract: Thermally induced deviations become the limiting factor for the precision of machine tools. Structure-based finite-element models of high resolution can estimate these deviations with high accuracy but have also a high computational effort. With model order reduction (MOR) these models can be converted into structure-preserving reduced-order finite-element models (FEM-MOR-models) which can be solved very efficiently in MATLAB/Simulink®. To improve model matching selective thermography is used. Selective thermography is a measurement method providing high structural resolution and minimal instrumentation expense due to the use of thermography and photogrammetric methods.

Abstract: This paper gives a short overview of the structure based correction of thermoelastic errors of machine tools. Measured load data of the machine control and structure based simulation models are used to calculate the error at the tool center point in thermal real time. The derived correction can be divided in modules, which are described on the example of a ball screw.

Abstract: Latest trend in increasing the performance characteristics of precision machines is reducing error in machines. Today research is focused on Machine tool accuracy. The effect of thermal error contributes to major part of 70% of volumetric error. The present study aims to establish a new compensation method for CNC Turning centre. Selection of proper temperature variables is a great task in thermal error compensation. In this paper 3 thermal process variables namely spindle speed; temperature and time are used to create thermal error models. Using ANSYS simulation experiments are created.

Abstract: The thermal error compensation and modeling is an effective way to improve the machining tool precision. This article took the CNC boring and milling center for example. Firstly, this article made analysis and research on the heat sources by analyzing the structural characteristics of CNC boring and milling center, and then on the basis of the previously measured data of selected critical temperature points, established the thermal error model using a method of multiple linear regression based on least square method. The model parameters were solved by MATLAB software. Finally, thermal error compensation model was tested.