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1
Content available Analysis of thermal characteristics with multi-physicsc oupling for the feed system of a precision CNC machine tool
Zheng Junjian, Deng Xiaolei, Yang Junshou, Zhang Wanjun, Lin Xiaoliang, Jiang Shaofei, Yao Xinhua, Shen Hongchen
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2024
|
Vol. 72, nr 2
art. no. e148941
EN
The machining accuracy of CNC machine tools is significantly affected by the thermal deformation of the feed system. The ball screw feed system is extensively used as a transmission component in precise CNC machine tools, responsible for converting rotational motion into linear motion or converting torque into repetitive axial force. This study presents a multi-physical coupling analysis model for the ball screw feed system, considering internal thermal generation, intending to reduce the influence of screw-induced thermal deformation on machining accuracy. This model utilizes the Fourier thermal conduction law and the principle of energy conservation. By performing calculations, the thermal source and thermal transfer coefficient of the ball screw feed system are determined. Moreover, the thermal characteristics of the ball screw feed system are effectively analyzed through the utilization of finite element analysis. To validate the proposed analysis model for the ball screw feed system, a dedicated test platform is designed and constructed specifically to investigate the thermal characteristics of the ball screw feed system in CNC machine tools. By selecting specific CNC machine tools as the subjects of investigation, a comprehensive study is conducted on the thermal characteristics of the ball screw feed system. The analysis entails evaluating parameters like temperature field distribution, thermal deformation, thermal stress, and thermal equilibrium state of the ball screw feed system. By comparing the simulation results from the analysis model with the experimental test results, the study yields the following findings: The maximum absolute error between the simulated and experimental temperatures at each measuring point of the feed system components is 2.4◦C, with a maximum relative error of 8.7%. The maximum absolute error between the simulated and experimental temperatures at the measuring point on the lead screw is 2.0◦C, with a maximum relative error of 6.8%. The thermal characteristics obtained from the steady-state thermal analysis model of the feed system exhibit a prominent level of agreement with the experimental results. The research outcomes presented in this paper provide valuable insights for the development of ball screw feed systems and offer guidance for the thermal design of machine tools.
2
Content available Applying rapid heating for controlling thermal displacement of CNC lathe
Than Van-The, Wang Chi-Chang, Ngo Thi-Thao, Guo Guan-Liang
Archive of Mechanical Engineering
|
2022
|
LXIX, nr 3
519--539
EN
Thermal error always exists in a machine tool and accounts for a large part of the total error in the machine. Thermal displacement in X-axis on a CNC lathe controlled based on a rapid heating system is presented in this paper. Positive Temperature Coefficient (PTC) heating plates are installed on the X-axis of the machine. A control temperature system is constructed for rapid heating which further helps the thermal displacement to quickly reach stability. The system then continuously maintains stable compensation of the thermal error. The presented rapid heating technique is simpler than the compensation of machine thermal errors by interference in the numerical control system. Results show that the steady state of the thermal displacement in the X-axis can be acquired in a shorter time. In addition, thermal errors in constant and varying working conditions could be significantly reduced above 80% and 60%, respectively, compared to those without using the rapid heating. Therefore, the proposed method has a high potential for application on the CNC lathe machine for improving its precision.
3
Content available Experimental research of paperboard cutting in die cutting press with the screw–nut transmission of drive mechanism of a movable pressure plate
Ternytskyi Serhij, Rehei Ivan, Kandiak Nazar, Radikhovskyi Ihor, Mlynko Oksana
Acta Mechanica et Automatica
|
2021
|
Vol. 15, no. 3
122--131
EN
This paper reports experimental research of torques during paperboard cutting in the die cutting press with the screw–nut transmission in the drive mechanism of the movable pressure plate. The purpose of the study is to substantiate the practical implementa-tion of the pressure plate drive mechanism with the use of screw–nut transmission for the production of cartons of paperboard blanks. The manufactured experimental bench for the research of paperboard blanks provides the possibility of getting dependencies of loads on different parameters of the die cutting process. The developed method of the experimental research envisages the use of the strain gauge method and the wireless module for data measurement and software for its processing that allow getting trustworthy results with minimum faults. As a result of experimental research studies, the impact of paperboard thickness and cutting velocity on torque values has been established. Results of experimental research allow getting trustworthy and systematised information about torque values depending on the thickness of the paperboard, the paperboard fibre direction and pressure plate displacement velocity. It is established that torque values on drive shaft during die cutting of paperboard blanks made of folding boxboard with thickness that lay in range of 0.3–0.7 mm. Experimental research studies show the impact of rotation speed of a drive shaft of the pressure plate drive mechanism on the torque value. The article shows the workability of the designed device with screw–nut transmission in the drive mechanism of a movable pressure plate.
4
Content available Ball screw unit precise modelling with dynamics of loads and moving heat sources taken into account
Jedrzejewski Jerzy, Kowal Zbigniew, Kwasny Wojciech, Winiarski Zdzislaw
Journal of Machine Engineering
|
2019
|
Vol. 19, No. 4
27--41
EN
This paper deals with the precision modelling of the ball screw unit’s thermal behaviour in the turning centre and its impact on the tool head positioning error. The error components along controllable axes X and Z are described in detail using an FE model integrating the changes in thermal and force loads and deformations occurring during the motion of the nut as a heat source. The impact of the nut work cycle on the thermal deformations of the ball screw and the displacements of the slideways and the screw points along both the axes and on carriage positioning precision is demonstrated.
5
Content available Precise modelling of machine tool drives with ball screw thermal behavior
Winiarski Z., Kowal Z., Jędrzejewski J., Kwaśny W.
Journal of Machine Engineering
|
2017
|
Vol. 17, No. 1
31--45
EN
This paper briefly describes the current requirements which machine tool ball screws must meet and indicates the need for the modelling and numerical simulation of the latter. The structure of a holistic ball screw model and ways of modelling the properties of the ball screw in a turning centre, including the moving heat sources on the guides and in the screw-nut joint, are presented. The results of computing the heating up and displacements of a preloaded screw and the screw without preload are reported. The modelled changes in motion resistance and in displacements are shown to be in agreement with the results of measuring the current drawn by the drive’s motor. It is also shown that the models represent well the real physical phenomena occurring in the ball screw during the execution of repeatable work cycles by the drive.
6
Implementacja bezprzewodowego układu kompensacji odkształceń cieplnych osi posuwu w tokarce CNC ze śrubą toczną
Zapłata J., Pajor M., Stateczny K.
Modelowanie Inżynierskie
|
2016
|
T. 27, nr 58
145--151
PL
W artykule przedstawiono bezprzewodowy system kompensacji odkształceń cieplnych śrub pociągowych zaimplementowany w tokarce typu Avia Turn. Funkcjonowanie systemu opiera się na pomiarze rozkładów temperatur za pomocą czujników umieszczonych we wnętrzu śrub pociągowych. Wykorzystano czujniki z wbudowanym interfejsem cyfrowym. Dane, zawierające wartości temperatur, przesyłane są do układu PLC obrabiarki za pomocą energooszczędnego, bezprzewodowego interfejsu. Zastosowanie opracowanych procedur obliczeniowych pozwala określić wartość poprawki redukującej wpływ odkształceń cieplnych na dokładność pozycjonowania osi. Wartość ta jest zależna od pozycji oraz aktualnego stanu temperaturowego. W pracy przedstawiono zarejestrowane doświadczalnie temperatury, odchyłki położenia osi napędowych oraz obliczone poprawki potwierdzające skuteczność działania opracowanego systemu kompensacji.
EN
The paper presents a wireless set for compensation of the thermal error of CNC axes installed in “Avia Turn”. The set uses temperature sensors installed inside ball screws for measuring the thermal state of CNC axes. The sensors have build-in digital interfaces. Thermal data are sent to the PLC of a CNC lathe by means of an energyefficient wireless interface. The developed mathematical model allows to compute correction values reducing the influence of the positioning thermal error. The correction values are position- and temperature-dependent. The measured temperatures, positioning thermal errors and evaluated correction values have been shown validating the functionality of the set.
7
Content available remote Modelowanie zjawiska konwekcji ciepła w zespole przekładni śrubowo-tocznej obrabiarek CNC z zastosowaniem sztucznych sieci neuronowych
Kowal M.
Mechanik
|
2016
|
R. 89, nr 8-9
1160--1161
PL
Zaprezentowano model opisujący zjawisko konwekcji w zespole przekładni śrubowo-tocznej. Przedstawiono sposób identyfikacji parametrów modelu, strukturę sztucznej sieci neuronowej i sposób doboru danych uczących, aby ostatecznie przedstawić wyniki walidacji modelu.
EN
In this article, the author presents a model describing the phenomenon of convection in ball screw. The author presents a method for identifying model parameters, the structure of artificial neuron network, the manner of selection of training data and finally the results of model validation.
8
Content available remote Analiza dynamiki układu kinematycznego dźwigniowego z przeładnią kulową do napędu ramienia manipulatora
Gruszka P.
Mechanik
|
2015
|
R. 88, nr 3CD
203--209
PL
W artykule przedstawiono problematykę syntezy wybranych wymiarów konstrukcyjnych płaskiego mechanizmu dźwigniowego, zawierającego w swej strukturze kinematycznej przekładnię śrubową toczną. Mechanizm ten wykorzystano do napędu ramion równoległoboku przegubowego wchodzącego w skład łańcucha kinematycznego manipulatora antropomorficznego z ortogonalną kiścią sferyczną. Przedstawiono wyniki symulacji numerycznych dynamiki mechanizmu. Analizie poddano wpływ wybranych wymiarów konstrukcyjnych mechanizmu na przebiegi wymaganych momentów napędowych ramion równoległoboku dla realizacji zadanej trajektorii.
EN
The paper presents the synthesis problem of the selected design dimensions of a flat lever mechanism, containing the ball screw in its kinematic structure. This mechanism is used to drive the arms of the parallelogram joints forming part of the kinematic chain of an anthropomorphic manipulator with the orthogonal spherical wrist. The results of the numerical simulation of dynamics of the mechanism were presented. There were analyzed the influence of the design dimensions of the mechanism on the courses of the required driving torques of the arms of the parallelogram for the implementation of the given trajectory.
9
Content available remote System CAD/CAM doboru przekładni śrubowych kulkowych do napędu obrabiarek
Sobolewski J. Z., Bonarowski J.
Mechanik
|
2010
|
R. 83, nr 1/S
237-246
PL
W IPBM PW opracowano program umożliwiający dobór przekładni, przy uwzględnieniu najważniejszych kryteriów dynamicznych napędu, znacznie szybszy niż jest to możliwe przy użyciu katalogów firmowych, w których brak jest niektórych istotnych informacji (np. sztywności składowych napędu z uwzględnieniem dokładności wykonania gwintu kulkowego, masy stołu itp.). Program jest dostępny w sieci (http://www.simr.pw.edu.pl/~jso/parkon/ index.html).
EN
Ball screws are used as an element of feed systems in machine tools working with constantly higher cutting speed. This paper contains the ball screws design methods with regard to dynamic conditions of a feed system. In the paper has been presented a CAD/CAM application which allows for the calculation of the ball screws parameters, static and dynamic axial load ratings, total rigidity and resonance of NC machine feed system.
10
Content available remote Wybrane przyczyny hałasu przekładni śrubowych kulkowych stosowanych w obrabiarkach
Sobolewski J. Z., Pieniecki P.
Mechanik
|
2009
|
R. 82, nr 3
190-194
PL
Dokonano analizy dwóch podstawowych źródeł hałasu przekładni śrubowych kulkowych stosowanych w obrabiarkach, a to pochodzącego od sił chwilowych w fazie przejściowej ruchu kulek oraz tarcia kulek o ściany kanału zwrotnego.
EN
Two possible sources of noise generated by recirculating ball screws installed in machine tools were reviewed; first, instantaneous forces developing during transient ball movement phase and second, balls rubbing over the return duct walls.
11
Content available remote Sztywność serwonapędów z gwintem kulkowym
Sobolewski J. Z.
Mechanik
|
2008
|
R. 81, nr 1
41-43
PL
Opisano nową metodę obliczania sztywności osiowej przekładni z gwintem kulkowym.
EN
A new method for calculation of axial rigidity in ball screw transmission units is suggested.
12
Content available remote Selected Sources of the Ball Screw Noise
Pieniecki P., Sobolewski J. Z.
Machine Dynamics Problems
|
2008
|
Vol. 32, No. 2
49-56
EN
Significant source of the noise is the circulation of balls in the closed circulation, especially in the transient zone of the balls' circulation, when a ball enters the working circulation and its load increases, or when it leaves the working circulation and its load decreases to zero. A transient phase forces take a major part on the ball screw friction phenomenon. Drill friction on ball track and friction on the inside surface of return elements are also important sources of the noise. Rolling quality coefficient depends on of nut and screw lead angle. Small ball diameter determinates accurate rolling quality, which decreases the noise emission. The adoption of new balls material (example ceramic) is recommended to meet the high load requirements on ball screw. Analysis of dynamic and friction phenomena is essential to understand properly the main noise sources on ball screw drive.
13
Content available Simulation investigation of ball screws for high speed transmitting systems
Sobolewski J. Z., Małkiński J., Pieniecki P.
Journal of Machine Engineering
|
2008
|
Vol. 8, No. 4
59--67
EN
The ball screws are used in feed systems in CNC machines working with constantly higher cutting speed. When the speed of the balls reaches certain levels, the repetitive chock (impact forces) generated by the balls in the "transient" phase of the balls' motion and forces acting in the return channel cause damage to the recirculation ball system. A simulation of impact forces for variable length of transient phase in function of the rotational speed was made. The static axial rigidity is a very important factor to be considered in defining ball screws performance and exerts a major influence on positioning accuracy of NC machine tools. One of rigidity components is the balls/balltrack area rigidity, dependent on Hertz's deflections. However, due to machining inaccuracies, the ball screws properties (especially rigidity) are considerably lower than the theoretical ones. A coefficient known as the geometric correction factor makes it possible to predict the rigidity of the ball screw. A computer simulation of the influence of machining inaccuracies on contact deflections, rigidity and servo drive resonance was carried out. It was examined what rotational speeds set off the harmful phenomenon of the agreement of the frequency of the arrangement of the impact forces with the frequency of the servo drive system resonance. The presented method allows for the calculation of the impact forces, total rigidity and resonance of NC machine feed system, in the preliminary phase of technical project.
14
Content available remote Some Remarks on the Ball Screw Rigidity
Sobolewski J. Z.
Machine Dynamics Problems
|
2006
|
Vol. 30, No. 4
122-130
EN
Rigidity is the main criterion for manufacturing quality of ball screws. One of rigidity components is the balls/balltrack area rigidity, dependent on Hertz' deflections. However, due to machining errors, the ball screws rigidity are considerably lower than the theoretical ones. On the basis of a mathematical model a computer simulation of the influence of machining errors on contact deflections was carried out. It proved that the rigidity of balls/balltrack area depends not only on accuracy grade but also on geometrical parameters of the thread. Measurements of ball screws rigidity were executed and the results were compared with the results of computers simulation. This effected a verification of computational model and a determination of the confidence level of calculations. A coefficient known as the geometry correction factor was introduced in order to estimate the influence of machining errors on lowering the level of nut unit rigidity. This coefficient was compared to the correction factor of accuracy applied in ISO standard for estimating ball screws rigidity.
15
Content available remote Mechaniczne rozwiązania w mechanizmach śrubowo-tocznych. Ruchoma nakrętka
Bachański W.
Napędy i Sterowanie
|
2003
|
R. 5, nr 6
27--28
PL
W ostatnich latach rozwinięto w branży mechanizmów śrubowo-tocznych różne rozwiązania, spełniające indywidualne wymagania użytkowników. Z prostego wyboru średnicy i skoku śruby tocznej powstała, dopasowana do wymagań Klientów, szeroka oferta tych mechanizmów. Ważne jest, aby przybliżyć najważniejsze cechy tego elementu w budowie maszyn.
16
Content available remote Modelling of the ball screw.
Sobolewski J.Z.
Archive of Mechanical Engineering
|
2002
|
Vol. XLIX, nr 4
317-328
EN
The author presents a development of computational model of design of ball screws thread. This model is the basis for computer program, which calculates the geometrical features of the thread for precisely given backlashes and contact angles. The program makes it possible to create the data base of a new generation ball screw of quality competitive to foreign ball screws. The modelling allows one to better select the ball screw and to predict its quality in the early stage of design.
PL
W pracy przedstawiono tworzenie obliczeniowego modelu do projektowania gwintu przekładni śrubowych kulkowych. Model ten jest bazą do programu komputerowego, który oblicza właściwości geometryczne gwintu dla założonego luzu osiowego i kąta działania kulek. Program ten umożliwia tworzenie bazy danych przekładni nowej generacji, o jakości konkurencyjnej do przekładni zagranicznych. Modelowanie ułatwia selekcję i przewidywanie jakości przekładni we wczesnej fazie projektowania.
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