Temat: thermal error - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Effects of hot chips in dry cutting processes on the temperature field and displacement of the machine tool table
Autorzy:: Albrecht, Tom
Thiem, Xaver
Penter, Lars
Ihlenfeldt, Steffen
Tematy:: accuracy
thermal error
deformation; Pokaż więcej
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Powiązania:: https://bibliotekanauki.pl/articles/99659.pdf Link otwiera się w nowym oknie
Opis:: In machining up to 75% of the geometrical variations of work piece, features are caused by thermally induced deformations of machine components [1]. Since in dry cutting up to 80% of the thermal energy is stored in the chips [2], we expected a significant effect of these process-dependent heat sources on the machine accuracy. Based on preliminary simulation results, we systematically applied determined quantities of heated chips to a machine table to understand their impact on the temperature field. Temperature sensors where used to measure the temperature change on the tables surface and in the structure. Length measuring probes measured the corresponding deformations at 24 points distributed over the table. The measurements show a temperature change of 4 K at the surface and 3 K in the structure near the heat source after 6 minutes of exposure to 500°C chips. In this case, the impact on the temperature field is local but causes the bending of the table. We recorded 8 micron of thermo-elastic deformations. The results suggest that high-accuracy processes with large energy input, such as hard turning, require the heat induced into the machine structure by hot chips to be implemented into compensation methods and correction algorithms.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Robustness and portability of machine tool thermal error compensation model based on control of participating thermal sources
Autorzy:: Mares, M.
Horejs, O.
Hornych, J.
Smolik, J.
Tematy:: control
machine tool
thermal error
transfer function; Pokaż więcej
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Powiązania:: https://bibliotekanauki.pl/articles/99925.pdf Link otwiera się w nowym oknie
Opis:: Thermal errors caused by the influence of internal and external heat sources in machine tool structure can cause more than 50% of total machine tool inaccuracy. Therefore, research on thermal behavior of machine tool structures is crucial for successful manufacturing. This paper provides an insight into the modeling of highly nonlinear machine tool thermal errors using thermal transfer functions (TTF). The method is dynamic (uses machine tool thermal history) and its modeling and calculation speed is suitable for real-time applications. The method does not require interventions into the machine tool structure, uses very few additional gauges and solves separately each influence participating on thermal error. The paper focuses on the development of a robust thermal model sensitive to various machine tool thermal behavior nonlinearities with the help of minimum input information. Model was applied on real machine tool (portal milling centre) and was verified within a complicated electro-spindle revolution spectrum. Moreover, the said compensation model was applied on another machine tool to prove its robustness and portability among machines of the same type set and the results of the TTF model were compared with a model obtained via multiple linear regression (MLR) as a case study.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Strategy for Compensation of Thermally Induced Displacements in Machine Structures Using Distributed Temperature Field Control
Autorzy:: Pöhlmann, Patrick
Müller, Jens
Ihlenfeldt, Steffen
Tematy:: control
machine tool
thermal error
thermal modal analysis; Pokaż więcej
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Powiązania:: https://bibliotekanauki.pl/articles/59124042.pdf Link otwiera się w nowym oknie
Opis:: Thermal deformation is a major source of machining errors in modern machine tools. In addition to optimising the machine structure, correcting the axis position values in the numerical control is a common measure to reduce these errors. Another possibility is to directly influence the temperature field of the machine tool in the process, which requires a complex thermo-elastic modelling approach as well as appropriate thermal actuation and measurement capabilities. This paper presents a strategy for controlling the temperature field based on the eigenmodes of the thermal system. The various aspects of the concept are explained using a finite element model of an exemplary structural component. The basis is the modal analysis of the thermal system, which allows the temperature field to be described by independent discrete states. In addition to the placement of thermal sensors and actuators, this work focuses on the design of a suitable control approach. Transient simulation results are used to clearly demonstrate the performance of this method.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Real-Time Compensation of Machine Tool Thermal Error Including Cutting Process
Autorzy:: Horejs, O.
Mares, M.
Hornych, J.
Tematy:: thermal error
real-time compensation
cutting process; Pokaż więcej
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Powiązania:: https://bibliotekanauki.pl/articles/99782.pdf Link otwiera się w nowym oknie
Opis:: The challenge to be addressed by this paper is to extend the common machine tool thermal compensation models considering only internal heat sources to include the effects of the cutting process. Although real-time software compensations of thermal errors exist, the majority of these models only presume machine tools under load-free rotation of the main spindle without any reference to rough machining. The machining process is completely neglected in spite of the fact that it represents a significant heat source and causes workpiece inaccuracy. This paper presents a real-time compensation of three-axis vertical milling centre thermal errors including the cutting process effect. The simulation is based on dynamic modelling using transfer functions. The model was implemented into a standard CNC controller of a three-axis vertical milling centre to compensate for thermal errors in real time. The inputs of the compensation algorithm are the spindle rotational speed, the 5 temperatures of the machine structure and spindle power. A reduction of thermal errors achieved by using the new approximation TF model including cutting process impact is up to 79% for steel cutting tests with different cutting conditions.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Decreasing of thermal errors in a lathe by forced cooling of ball screws and a headstock
Autorzy:: Winiarski, Z.
Kowal, Z.
Błażejewski, A.
Tematy:: lathe
feed mechanism
cooling
thermal error
calculation; Pokaż więcej
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Powiązania:: https://bibliotekanauki.pl/articles/1429161.pdf Link otwiera się w nowym oknie
Opis:: The goal of this paper is to present the effective methods of decreasing thermal deformations of a turning centre's structure in order to reduce the thermal error. The design of a machine tool as well as the scope of analyses are described, and calculation methods are specified. The paper also presents the results of computer simulations, concerning studies on the influence of type and parameters of a headstock-cooling liquid on the reduction of spindle displacements. Moreover, the results of feed mechanism's thermal studies are shown, describing the influence of heat generated during the operation of ball screws and their inner liquid cooling, on tool's thermal displacements.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Investigation of Tool Cooling and Heat Transfer Using Computational Fluid Dynamics Simulations
Autorzy:: Naumann, Christian
Schmidt, Claus-Dieter
Geist, Alexander
Brier, Steffen
Glänzel, Janine
Klimant, Philipp
Ihlenfeldt, Steffen
Dix, Martin
Tematy:: machine tool
CFD simulation
thermal error
tool cooling; Pokaż więcej
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Powiązania:: https://bibliotekanauki.pl/articles/59124038.pdf Link otwiera się w nowym oknie
Opis:: Thermal errors remain one of the biggest challenges for the precision of cutting machine tools. Aside from optimizations in the machine tool design and behaviour, optimal cutting process parameters and targeted usage of cutting fluid or alternative methods of tool cooling are required for improved process efficiency with minimal energy demand and maximal tool life. A simulation-based study is presented which compares both different methods of tool cooling, specifically air cooling, flooded cooling and minimum quantity lubrication and also different simulation methods and models. Using a case study, which models an existing thermal test stand comprised of motor spindle, tool holder, tool and coolant nozzle, different cooling scenarios were tested and compared. The simulations were performed in ANSYS CFX. Comparisons were made between simulations with and without buoyancy, with and without tool rotation, transient and steady-state, with laminar flow and with different turbulence models and between the different cooling scenarios. Some insight on different time step sizes and the resulting increase in simulation time and precision was also gained. These results will make future studies on the thermal behaviour of both tool and cutting process easier by showing suitable simulation techniques and viable model simplifications.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Compensation of machine tool angular thermal errors using controlled internal heat sources
Autorzy:: Mares, M.
Horejs, O.
Hornych, J.
Kohut, P.
Tematy:: control
machine tool
angular thermal error
transfer function; Pokaż więcej
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Powiązania:: https://bibliotekanauki.pl/articles/971270.pdf Link otwiera się w nowym oknie
Opis:: Thermal errors caused by the influence of internal and external heat sources in machine tool structure can cause up to 70% of total machine tool inaccuracy. Therefore, research on thermal behavior of machine tool structures is crucial for successful manufacturing. This paper provides an insight into the modeling of highly nonlinear (increasing with the complexity of the structure) machine tool thermal behavior using thermal transfer functions This approach to modeling is dynamic (uses thermal history) and, due to its relative simplicity, it enables real-time calculations. The method uses very few additional gauges and solves separately each influence participating in the thermal error. The main objective of the article is to describe the estimation of angular deformations occurring at the tool center point due to thermal influences. Transfer functions are used for the identification and control of additional internal heat sources. The second aim is to compare modeling effort with approximation quality. A partial objective is to cover other nonlinearities occurring generally in machine tool thermal behavior. The approach has been verified on a closed quill (a simple and symmetrical machine tool part) and applied on a model of a machine tool structure which has been chosen as the least favorable from the thermal point of view.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Model-based, experimental thermoelastic analysis of a large scale turbine housing
Autorzy:: Emonts, Dominik
Sanders, Mark P.
Montavon, Benjamin
Schmitt, Robert H.
Tematy:: thermal error modelling
large scale metrology
virtual climatisation; Pokaż więcej
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Powiązania:: https://bibliotekanauki.pl/articles/2052191.pdf Link otwiera się w nowym oknie
Opis:: Temporally and spatially unstable thermal conditions lead to inhomogeneous thermoelastic changes in the workpiece geometry. Consequently, non-negligible geometric deviations are evident, especially when measuring large workpieces with narrow tolerances, which often take place in non-climatized production environments and thus make thermal monitoring indispensable. Accurate determination of the thermoelastic behaviour for complex and large geometries is a challenging task with computationally effortful or less accurate existing solutions. Thus, the development of innovative measurement and modelling approaches is subject of current research, whereat physical validation is a prerequisite. Therefore, the authors developed a method, enabling the emulation of typical process heat cycles on a turbine housing in combination with a geometric measurement system. The idea is to provide reproducible and reversible thermal conditions on a representative large workpiece and to investigate the resulting geometric deformation in an economically viable way. Throughout this study, an analogy test rig is presented, integrating different temperature sensors, two geometric measurement systems and thermal deformation models into one demonstrator. The demonstrator's first applications show insightful results, revealing accordance, but also unexpected deviations between the predicted and measured quantities. Moreover, it provides great potential for validation of more complex modelling approaches and innovative thermal condition monitoring systems for large precision workpieces.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Implementation and demonstration of characteristic diagram as well as structure model based correction of thermo-elastic tool center point displacements
Autorzy:: Putz, M.
Ihlenfeldt, S.
Kauschinger, B.
Naumann, C.
Thiem, X.
Riedel, M.
Tematy:: hexapod
characteristic diagram
thermal error
simulated
measured
correction algorithm; Pokaż więcej
Wydawca:: Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Powiązania:: https://bibliotekanauki.pl/articles/99680.pdf Link otwiera się w nowym oknie
Opis:: In milling machines, waste heat from motors, friction effects on guides and most importantly the milling process itself greatly affect positioning accuracy and thus production quality. Therefore, active cooling and lead time are used to reach thermal stability. A cheaper and more energy-efficient approach is to gather sensor data from the machine tool to predict and correct the resulting tool center point displacement. Two such approaches are the characteristic diagram based and the structure model based correction algorithms which are briefly introduced in this paper. Both principles have never been directly compared on the same demonstration machine, under the equal environmental conditions and with the same measurement setup. The paper accomplishes this comparison ona hexapod kinematics examined in a thermal chamber,where the effectiveness of both approaches is measured and the strengths and weaknesses of both are pointed out.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Supervising and compensation of thermal error of CNC feed ball screw
Nadzorowanie termiczne oraz kompensacja błędów odkształceń cieplnych śrub pociągowych obrabiarek CNC
Autorzy:: Pajor, M.
Zapłata, J.
Tematy:: thermal error
feed screw
monitoring
odkształcenia cieplne
śruba pociągowa; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Powiązania:: https://bibliotekanauki.pl/articles/329402.pdf Link otwiera się w nowym oknie
Opis:: The paper presents a set allowing for on-line monitoring of machine tool feed screw temperature. Indirect supervising of the feed screw thermal elongation protects ball bearings from excessive loads. Moreover, the usage of an appropriate model in the control system of the CNC machine tool allows for the reduction of ball screw thermal errors.
Prezentowany w pracy układ pozwala na monitorowanie „on-line” temperatury śruby pociągowej obrabiarki. Pośredni nadzór wydłużenia cieplnego śruby zabezpiecza przed nadmiernym obciążeniem łożysk tocznych na skutek wydłużenia cieplnego śruby pociągowej. Dodatkowo zastosowanie odpowiedniego modelu w systemie sterowania obrabiarki CNC pozwala na redukcję „on-line” błędów pozycjonowania wynikających z odkształceń cieplnych śrub pociągowych obrabiarki.
Dostawca treści:: Biblioteka Nauki

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