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1

Development of FEM thermal simulation technology for machine tool with enclosures and its application

Tanabe Ikuo, Suzuki Naohiko, Ishino Yoshiaki, Isobe Hiromi

Journal of Machine Engineering

|

2024

|

Vol. 24, No. 1

17--28

EN

These days, most machine tools are interlocked by an enclosure for safety control. At that time, internal heat generation in machine tools first causes thermal deformation of the machine structure, which reduces the machining accuracy of the workpiece. Furthermore, the internal heat generation heats the air inside the enclosure, causing a heat build-up phenomenon, and the trapped heat causes re-thermal deformation of the machine tool structure. As a result, machine tools with enclosures are subject to extremely complex thermal deformation. On the other hand, we would like to use FEM thermal simulation to study thermal deformation countermeasures for machine tools with enclosures at the design stage, but it is difficult to analyse the heat build-up phenomenon usingconventional FEM thermal simulation. In this research, the new FEM thermal simulation technology for the heat build-up phenomenon was developed and heat build-up phenomenon in a CNC lathe with enclosure was calculated using the proposed FEM simulation technology. As a result, it had been concluded that the proposed FEM simulation could calculate with high accuracy for the phenomenon of heat build-up in a CNC lathe with enclosure, and the proposed technology is very effective in the design.

2

Deformacje kompozytów cementowych w wysokich temperaturach

Plechawski Stanisław

Budownictwo i Prawo

|

2023

|

R. 26, nr 3

25--30

PL

W artykule przedstawiono zagadnienia wpływu wysokich temperatur na deformacje kompozytów cementowych: beton, zaczyn i zaprawę. Jest to fragment szerzej prowadzonych badań własnych oddziaływania temperatur pożarowych na wybrane parametry struktury betonów, w których za wiodący temat uznano odporność na pękanie wyrażoną poprzez krytyczny współczynnik intensywności naprężeń KIC . Wykonano też inne, niezbędne badania kompozytów cementowych m.in. wytrzymałości na ściskanie, rozciąganie przy zginaniu i przez rozłupywanie, dynamicznego modułu sprężystości, a także badania odkształceń próbek betonu, zaczynu i zaprawy, zmiany ich objętości oraz ubytki masy, jak również obserwacje i badania SEM. Składy badanych kompozytów nie zawierały żadnych dodatków ani domieszek z uwagi na wiarygodność badań pod wpływem wysokich temperatur. Dodatkowe składniki w zależności od ich rodzaju, proporcji, pochodzenia itp. mogą wpływać na niejednoznaczność otrzymanych wyników. Publikowane przez różnych autorów badania nie zawsze są jednoznaczne i miarodajne dla wszystkich rodzajów betonu. Badania takie stanowią podstawę do oceny bezpieczeństwa, trwałości i niezawodności konstrukcji po pożarze.

EN

The article presents the issues of the impact of high temperatures on the deformation of cement composites: concrete, paste and mortar. It is a fragment of the widely conducted own research on the impact of fire temperatures on selected parameters of concrete structure, in which crack resistance expressed by the critical stress intensity factor KIC was recognized as the leading. Other necessary tests of cement composites were also carried out, including compressive strength, tensile strength at bending and splitting, dynamic modulus of elasticity, as well as testing deformations of concrete, paste and mortar samples, changes in their volume and weight loss, as well as SEM observations and tests. The compositions of the tested composites did not contain any additions or admixtures due to the reliability of the tests under the influence of high temperatures. Additional ingredients depending on their type, proportion, origin, etc. may affect the ambiguity of the results obtained. Studies published by various authors are not always unambiguous and authoritative for all types of concrete. Such studies are the basis for assessing the safety, durability and reliability of structures after a fire.

3

Tests of Mechanical and Thermal Deformation of Moulding Sands Produced in Various Technologies

Grabarczyk Aleksandra, Major-Gabryś Katarzyna, Jakubski Jarosław, Dobosz Stanisław Marian, Bolibruchová Dana, Pastirčák Richard

Archives of Metallurgy and Materials

|

2023

|

Vol. 68, iss. 3

933--937

EN

Casting industry has been enriched with the processes of mechanization and automation in production. They offer both better working standards, faster and more accurate production, but also have begun to generate new opportunities for new foundry defects. This work discusses the disadvantages of processes that can occur, to a limited extend, in the technologies associated with mould assembly and during the initial stages of pouring. These defects will be described in detail in the further part of the paper and are mainly related to the quality of foundry cores, therefore the discussion of these issues will mainly concern core moulding sands. Four different types of moulding mixtures were used in the research, representing the most popular chemically bonded moulding sands used in foundry practise. The main focus of this article is the analysis of the influence of the binder type on mechanical and thermal deformation in moulding sands.

4

Application of the pentagonal W-ECO model for manufacturing based on "SDGs"

Tanabe Ikuo

Journal of Machine Engineering

|

2022

|

Vol. 22, No. 1

25--42

EN

The Sustainable Development Goals (SDGs) were proposed to ensure the well-being of everyone on earth, a purpose to which all the fields, including manufacturing, must contribute. However, although industry is implementing this laudable concept in a piecemeal fashion, it is currently unlikely to achieve all 169 targets in the 17 Goals by the SDG deadline of 2030. Therefore, qualitative and quantitative achievement indicators and effective evaluation methods are needed to achieve the 17 goals of the SDGs when developing industrial products. Therefore, in this study, the manufacturing in response to the 17 goals and the 169 targets of the SDGs is considered, and the application of the pentagonal W-ECO model for manufacturing based on the SDGs was proposed. First, the current situation of manufacturing was considered from an environmental perspective, which is also important for the SGDs. Secondly, product’s lifespan which is deeply related to the environment, was discussed in terms of the correlation between time, technology and environment, and "Re" technology was proposed to extend product's lifespan and save resources. Then three cases of development for environmental conservation were introduced to understand the current situation, and it was confirmed that the new technologies in the three cases can contribute to the achievement of SDGs, however the degree of their contribution couldn't be evaluated quantitatively. Finally, the previous three cases using the proposed pentagonal W-ECO model quantitatively evaluated and confirmed that the results of the evaluation provide a quantitative indicator for achieving the SDGs. As a result, the effectiveness of the pentagonal W-ECO model for manufacturing based on SDGs is evaluated.

5

Stress-strain state simulation of non-uniformly heated elements of components and assemblies of automotive

Hrevtsev O., Selivanova N., Popovych P., Poberezhny L., Brych V. Ya., Rudyak Yu., Shevchuk O., Bakulina N., Rozum R., Buriak M.

Journal of Achievements in Materials and Manufacturing Engineering

|

2022

|

Vol. 115, nr 1

26--32

EN

Purpose: Develop a method for determining and evaluating the stress-strain state, particularly the distribution of thermomechanical stresses in the materials of individual rotating parts of vehicles. Design/methodology/approach: The proposed method is based on the principle of gradual approximations of the solution when the boundary conditions are satisfied on the curvilinear limiting surfaces of the disk body. Findings: The proposed method of determining and estimating the distribution of thermomechanical stresses in the disk material makes it possible to take into account the variable geometry: thickness and presence of a hole in the central part of the disk, also correctly determine stress-strain state at any point of unevenly heated rotating axial body. Research limitations/implications: The work uses generally accepted assumptions and limitations for thermomechanical calculations. Originality/value: It is proved that in real disks, the stress-strain state is spatial, and the well - known method based on the hypotheses of the plane-stress state does not provide the possibility of calculating the values of stresses in the thickness of the disk. The obtained results can be used to improve the methodology of auto technical examination of road accidents. In addition, they can be taken into account by bus drivers on urban routes when choosing a safe distance in heavy traffic, as well as design engineers of car brake systems.

6

PVA hydrogel deformation in response to change in temperature or pH

Kazimierska-Drobny Katarzyna

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2021

|

Vol. 69, nr 2

art. no. e136724

EN

Biocompatibility, biodegradability and non-toxicity are the main attributes of any material to be used in biomedical applications. Among all the potential stimuli, pH, salt and temperature exist naturally in the internal environment of the human body. Hence internal stimuli responsive hydrogels can be exploited for specific drug delivery and tissue replacement. Poly(vinyl alcohol) (PVA) is the world’s largest volume synthetic polymer, produced for its excellent chemical resistance, physical properties and complete biodegradability, which has resulted in broad practical applications. PVA could be considered a suitable host material due to its good thermo-stability, chemical resistance and film-forming ability. It is also an important material because of its large-scale applications. Novel data analysis techniques were developed to analyze the response of PVA to external stimuli, including temperature and/or pH. The presented non-contact method shows that the PVA polymer gel, physically cross-linked by freezing and thawing, shrinks and swells under the influence of temperature, which is a reversible phenomenon. Under the given conditions, such as temperature, pH and mechanical load, the dominant factor affecting the swelling or contraction of the hydrogel is the change in the temperature of the liquid in which the PVA hydrogel sample is immersed.

7

Study of Physical and Mechanical Properties of Steel During Grinding and Sharpening

Biały Witold, Ivanova Tatiana Nikolaevna, Žarnovský Jozef, Ružbarský Juraj

Multidisciplinary Aspects of Production Engineering

|

2020

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Vol. 3, Iss. 1

128--140

EN

A direct influence on the physical and mechanical state of the surface layer of wedge-shaped plates made of 8KHF steel is exerted by heat generation processes developing in the zone of a high-speed thermal process. Research on the influence of the parameters of a high-speed thermal process on the change in the structure of 8KHF steel (GOST 5950-2000 Russia, standard PN/H 85023 brand NCV1 Poland) was fulfilled. It allowed studying the nature of the change in the microstructure depending on short-term heating to various temperatures and rapid cooling. As a result, critical points of the beginning and the end of structural transformations during heating were determined. Research on thermal processes in a high-speed thermal process made it possible to establish regularities of influence of cutting speed, source speed, contact area, coolant properties and heat transfer coefficient on the temperature and rate of thermal processes in surface layers, as well as their impact on the depth of heating to a certain temperature. The study also allowed us to show the relationship between temperature and rates of heating and cooling. The solution to this problem, taking into account the action of the cooling fluid, gives the opportunity to bring the picture of the development of thermal processes closer to real conditions and makes it possible to reasonably predict the structural state of the surface layer of wedge-shaped parts made of 8KHF steel under various conditions of a high-speed thermal process.

8

Investigation of thermomechanical processes in miniature membrane elastic elements

Tykhan M., Dilay I., Markina O., Markovych V.

Journal of Achievements in Materials and Manufacturing Engineering

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2020

|

Vol. 98, nr 1

24--31

EN

Purpose: The demand for the devices structures reliability and machines requires understanding elements operation, in particular elastic elements, under the effect of nonstationary temperature factors. Therefore, it is important to investigate the behaviour of these elements under variable temperature effecting. Design/methodology/approach: In this article, the temperature field and the thermal stresses of the membrane type elastic elements, as well as the thermal deformation of its body part were investigated by the method of numerical analysis. The theoretical results have experimental confirmation. Findings: The article shows possibilities significantly reduce the thermal stress in an elastic element, thereby increase its functional and structural reliability by varying the geometric parameters of the elastic element, the materials selection, and body shape. Research limitations/implications: Numerical modelling of thermal processes requires accurate information about the physico-mechanical properties of materials and heat-exchange coefficient, which in practice may differ from the theoretical ones. Therefore, experimental confirmation of research and decisions is needed. The influence of the "hot" thermal shock was investigated. There is performed interest to investigate the "cold" thermal shock. Practical implications: The obtained results allow creating elastic elements with better functional characteristics for operation in a wide temperature range. They can also be used in the designing of elastic elements not only of membrane type. Originality/value: Performed investigation of thermomechanical processes in the membrane elastic element has revealed important features of its temperature deformations with nonstationary thermal influence. Namely, the nature of thermal deformations can be changed by selecting the geometrical parameters of the element, its material, as well as the conditions of heat-exchange conditions with mating member (body). In this way, it is possible to obtain a controlled deformation and to design the elastic elements with predetermined functional tasks. On the other hand, the design of the membrane element body can create elastic hinges, which allows reducing the thermal stress in the membrane, which significantly increases the reliability of the element operation of this type in conditions of non-stationary temperatures. In general, the conducted investigations allow efficient design of elastic elements for devices, sensors and other precision mechanisms.

9

The Influence of Moulding Sand Type on Mechanical and Thermal Deformation

Grabarczyk A., Major-Gabryś K., Dobosz S. M., Jakubski J., Bolibruchová D., Brůna M., Pastirčák R.

Archives of Metallurgy and Materials

|

2019

|

Vol. 64, iss. 1

347--351

EN

Casting industry has been enriched with the processes of mechanization and automation in production. They offer both better working standards, faster and more accurate production, but also have begun to generate new opportunities for new foundry defects. This work discusses the disadvantages of processes that can occur, to a limited extend, in the technologies associated with mould assembly and during the initial stages of pouring. These defects will be described in detail in the further part of the paper and are mainly related to the quality of foundry cores, therefore the discussion of these issues will mainly concern core moulding sands. Four different types of moulding mixtures were used in the research, representing the most popular chemically bonded moulding sands used in foundry practise. The main focus of this article is the analysis of the influence of the binder type on mechanical and thermal deformation in moulding sands.

10

Assessment of shear stresses from shrinkage and thermal deformation in wood-concrete bridge beams

Furtak K.

Archives of Civil Engineering

|

2019

|

Vol. 65, nr 4

37--50

EN

The aim of the paper is to assess the values of shear (delaminating) stress in the composition plane between the concrete (RC) deck slab and wood girder from concrete shrinkage, and shrinkage and swelling of wood, as well as difference in temperature between the wood web and concrete slab.

11

Wpływ sposobu nagrzewania i grubości rdzeni pomiarowych wykonanych z oliwinowych mas formierskich z krzemianem sodu na odkształcalność badaną na urządzeniu DMA Hot-Distortion

Stachowicz M., Paduchowicz P.

Prace Instytutu Odlewnictwa

|

2018

|

Vol. 58, no. 4

277--293

PL

W artykule podjęto tematykę wpływu podwyższonej temperatury na oliwinowe masy formierskie i rdzeniowe ze spoiwem nieorganicznym z grupy niemodyfikowanych gatunków uwodnionego krzemianu sodu. Sporządzone w warunkach laboratoryjnych masy na osnowie piasku oliwinowego formowano w kształtki prostopadłościenne do badania przemieszczenia wolnego końca rdzenia pomiarowego w warunkach otoczenia o podwyższonej temperaturze. W celu utwardzenia, wykonane z mas oliwinowych, kształtki poddawano szybkiemu nagrzewaniu mikrofalowemu w piecu z generatorem częstotliwości fali elektromagnetycznej f = 2,45 GHz i mocy wyjściowej 1000 W, w czasie 180 s. Badania przeprowadzono na kształtkach prostopadłościennych formowanych we wnęce o wymiarach: 25,9 × G × 120,4 mm, gdzie G = 6 lub 8, lub 10 mm. Pomiary przemieszczeń wolnego końca kształtek rdzeni pomiarowych przeprowadzono na zautomatyzowanym urządzeniu laboratoryjnym DMA Hot- Distortion. W trakcie pomiarów zastosowano trzy sposoby ogrzewania powierzchni prostopadłościennych kształtek spotykanych w technice pomiarowej odkształceń H-D (Hot Distortion Test): grzanie od dołu, grzanie od dołu i od góry (Modified Hot Distortion Test) oraz ogrzewanie tylko od góry. Przemieszczenie wolnego końca kształtek prostopadłościennych, w zależności od grubości oraz sposobów ogrzewania ich powierzchni, posłużyło do wstępnej oceny zachowania utwardzonych mikrofalowo mas oliwinowych z krzemianem sodu w warunkach otoczenia o podwyższonej temperaturze.

EN

The article raises the issue of the influence of increased temperature on olivine moulding and core sands with an inorganic binder from the group of unmodified kinds of hydrated sodium silicates. Produced at laboratory conditions, moulding sands with an olivine sand matrix were formed into cuboidal specimens to test the deformation of the free measuring core end at conditions of increased temperature. In order to harden, the measuring cores made of olivine moulding sands fast microwave heating was applied to which used was a furnace with an electromagnetic wave frequency generator f = 2.45 GHz and output power of 1000 W, in the time period of 180 s. Tests were carried out on cuboidal specimens moulded in a cavity with the dimensions 25.9 × G × 120.4 mm, where G = 6 or 8 , or 10 mm. Measurements of deformation of the free specimen end of the measuring cores were conducted on an automated laboratory DMA Hot-Distortion apparatus. During the measurements three techniques were used to heat the surfaces of cuboidal specimens which are applied in the Hot Distortion Test: heating from the bottom, heating from the bottom and the top (Modified Hot Distortion Test), and heating only from the top. The deformation of the free end of cuboidal specimens, depending on the thickness and heating techniques of their surfaces, served for the initial assessment of the behaviour of microwave hardened olivine moulding sands with sodium silicate at conditions of increased temperature.

12

System kompensacji odkształceń cieplnych śruby pociągowej. Kompensacja błędów w maszynach ze sterowaniem FANUC 31i-B

Miądlicki K., Majda P., Zapłata J.

Napędy i Sterowanie

|

2018

|

R. 20, nr 11

18--21

PL

Współczesne obrabiarki muszą spełniać wiele wymagań, z których najważniejszym jest osiąganie wysokiej dokładności i powtarzalności wytwarzanych wyrobów. Niestety, istnieje też wiele czynników, które mogą wpłynąć na błąd pozycjonowania elementów wykonawczych maszyn. Jednym z najlepszych sposobów zapobiegania problemom jest wyposażanie obrabiarek w zaawansowane systemy sterowania CNC, umożliwiające skuteczną kompensację błędów.

13

Symulacja odkształceń termicznych przedmiotu obrabianego na maszynie CNC przy wysokodokładnej obróbce szybkościowej

Wąsik M., Kolka A., Śliwka J.

Modelowanie Inżynierskie

|

2018

|

T. 35, nr 66

87--94

PL

W artykule omówiono zagadnienie obróbki wysokodokładnych systemów wytwórczych. Podczas prac wdrożeniowych elastycznego systemu w autonomicznej produkcji napotkano utrudnienia. Dokładność dotycząca elementów o regularnych kształtach jest na satysfakcjonującym poziomie, jednakże przy obróbce elementów cienkościennych o złożonych kształtach z lekkich stopów metali ważny jest dobór odpowiednich warunków skrawania, takich jak wpływ otoczenia lub energii cieplnej. Kolejnym problemem jest różnica pomiędzy temperaturami maszyny, przedmiotu obrabianego i otoczenia, co powodują spadek dokładności obróbki mimo zastosowania aktywnych systemów kompensacji odkształceń maszyny. Artykuł prezentuje nowatorski sposób poprawy jakości obróbki poprzez zastosowanie w nastawach maszyny parametrów wynikających z obliczeń MES odkształceń termicznych przedmiotu obrabianego.

EN

During the work at the implementation of flexible machining system for autonomous production some challenging difficulties were found. For workpieces of a regular shape, the achieved machining accuracy is satisfactory but for workpieces of a complex shape and thin walls form light alloys machining it is still difficult to find proper environmental conditions without separating the machine form among others outer temperature impact. Another problem is the difference between machine, workpiece and ambient temperature so that the machining accuracy is decreasing even if machine tool’s active systems compensate the machine’s thermal deformations. An approach to improve the machining accuracy with high accuracy machining systems by using special adjustment procedures and additional workpiece’s distortion compensations based on FEM simulations are presented in the paper.

14

Machine tool distortion estimation due to environmental thermal fluctuations – a focus on heat transfer coefficient

Da Silva P., Pena-Gonzalez L. E., Tanabe I., Takahashi S.

Journal of Machine Engineering

|

2018

|

Vol. 18, No. 2

17--30

EN

Thermally induced errors have been approached in multiple ways due to the influence these have over the positional accuracy of a machine tool. Here, approaches regarding environmental thermal fluctuations surrounding a machine tool remain to be explored in detail. These fluctuations have been explored in terms of the heat transfer coefficient and thermal radiation of the machine shop walls, as well as in terms of seasonality and varying thermal gradients. This paper presents additional considerations regarding environmental temperature perturbations, as heat transfer coefficient fluctuations in the machine shop were thought to play a significant role in machine tool thermal deformation a broader term for these phenomena, environmental thermal fluctuations, was defined and evaluated. Specifically, an environmental thermal data survey of a machine shop was explored. This data was then applied to a NC milling machine and a CNC jig borer FEM analyses and compared to experimental data. FEM simulations were then used to demonstrate that convection regimes and heat transfer coefficient values at a machine shop have a significant influence over machining precision. Here, under maximum and minimum heat transfer coefficient values, the NC milling machine and CNC jig borer simulations results showed an error of cut difference up to 36.5 μm and 18.17 μm, respectively. In addition, as the importance of the heat transfer coefficient was highlighted, considerations regarding machine tool surface color were deemed relevant and were described.

15

Bezstykowe nawierzchnie szynowe i betonowe

Witakowski P.

Inżynieria i Budownictwo

|

2018

|

R. 74, nr 4

213--218

PL

Klasyczne nawierzchnie szynowe od kilkudziesięciu lat zastępuje się z powodzeniem pozbawionymi dylatacji nawierzchniami bezstykowymi. Warunkiem bezpieczeństwa jest przymocowanie szyny do podkładów w sposób zapewniający, że temperatura neutralna, przy której naprężenia w szynie się zerują, wyniesie około 23°C. Podobna zasada umożliwia konstrukcję bezstykowej nawierzchni betonowej. Warunkiem jest zapewnienie temperatury neutralnej poniżej –20°C.

EN

Classic track structure for tens years have were replaced with success by jointless rail tracks. The condition of safety is a fastening of a rail to sleepers in such a way, that it assures neutral temperature (in which tension in rail disappear) ca. 23°C. The similar principle makes possible the construction of jointless concrete pavement. The condition is an assurance of neutral temperature below –20°C.

16

Thermal Deformation of Moulding and Core Sands with an Inorganic Binder Containing a Relaxation Additive

Bobrowski A., Drożyński D., Jakubski J., Szumera M., Kaczmarska K., Grabowska B.

Archives of Foundry Engineering

|

2018

|

Vol. 18, iss. 4

93--98

EN

The paper presents the results of an investigation of the thermal deformation of moulding sands with an inorganic (geopolymer) binder with a relaxation additive, whose main task is to reduce the final (residual) strength and improves knocking-out properties of moulding sand. The moulding sand without a relaxation additive was the reference point. The research was carried out using the hot-distortion method (DMA apparatus from Multiserw-Morek). The results were combined with linear deformation studies with determination of the linear expansion factor (Netzsch DIL 402C dilatometer). The study showed that the introduction of relaxation additive has a positive effect on the thermal stability of moulding sand by limiting the measured deformation value, in relation to the moulding sand without additive. In addition, a relaxation additive slightly changes the course of the dilatometric curve. Change in the linear dimension of the moulding sand sample with the relaxation additive differs by only 0.05%, in comparison to the moulding sand without additive.

17

Modified Hot Distortion Test to Investigate the Effect of the Inorganic Binder on the High-Temperature Behaviour of Physically Hardened Moulding Sands

Stachowicz M.

Archives of Foundry Engineering

|

2018

|

Vol. 18, iss. 2

45--50

EN

This study is an attempt to determine by Hot Distortion Test (HDT) the impact of physical methods of hardening inorganic binders in the moulding sands on phenomena caused by influence of thermal energy from heating elements with a temperature of 900°C +/- 10°C. Medium silica sand-based moulding mixtures were densified and then hardened using two physical methods: microwave heating at a frequency of 2.45 GHz or classical drying at a temperature of 110°C. Sodium silicate bonded sand (SSBS) with five unmodified kinds of hydrated sodium silicates subjected to two different types of hardening method were assessed in terms of their behaviour in high temperature. Thermal behaviour by means of deformation measurement was carried out with a modified Hot Distortion Test (mHDT). Due to this advanced, but unstable by appropriate standards Hot Distortion Test gives an opportunity to measure thermoplastic deformations (L) in moulding sands in many aspects, such as time of annealing. Research carried out in this way exposed differences between inorganic binders with molar module ranging from 3.4 to 2.0. It was established that deformations under the influence of high temperature last the longest in SSBS containing binders with molar module ranging from 3.4 to 2.9. Similarly, for these types of moulding sands the method of hardening the binder is found to be essential for increasing/decreasing the rate of thermoplastic deformations during the annealing of samples. The samples of SSBS made with binders with molar module from 2.5 to 2.0 are found to be excessively susceptible to thermoplastic deformation as a result of heating them in high environmental temperature presence.

18

Modelowanie odkształceń cieplnych obrabiarki precyzyjnej metodą MES

Zapłata J.

Modelowanie Inżynierskie

|

2017

|

T. 32, nr 63

114--122

PL

W artykule przedstawiono wyniki zamodelowanych, za pomocą metody elementów skończonych, odkształceń cieplnych frezarki CNC wynikające z pracy jej napędu głównego. Omówiono model cieplny obrabiarki, jej model mechaniczny oraz procedury umożliwiające obliczenie warunków granicznych dla wspomnianych modeli. Celem publikacji jest ukazanie wpływu, jaki wywierają poszczególne warunki brzegowe przyjmowane w toku modelowania na wyniki końcowe analiz odkształceń cieplnych. Proces szacowania poszczególnych warunków brzegowych jest czasochłonny, szczególnie w przypadku braku gotowych aplikacji umożliwiających ich obliczenie. Ponadto wymaga on często specjalistycznej wiedzy. Dlatego możliwość pominięcia niektórych zjawisk lub dopuszczenia większego marginesu błędu ich oszacowania, bez znaczącego pływu na wyniki końcowe analizy, jest korzystna dla konstruktorów oceniających wartości odkształceń cieplnych obrabiarek precyzyjnych za pomocą metody MES.

EN

The paper presents results of FEM analysis of CNC milling machine thermal error arising during its spindle work. The thermal and mechanical model were presented. Procedures allowing to estimate the border conditions were described. The paper aims to assess the influence of relevant border conditions on FEM analysis results. The process of evaluating the border conditions requires specific knowledge and is time-consuming, especially if no dedicated software is accessible. Therefore possibility to neglect insignificant phenomena or to widen allowed estimation error margin, without noticeably influencing analysis result, is valuable for designers evaluating thermal errors by means of FEM analysis.

19

Impact of Density Degree and Grade of Inorganic Binder on Behavior of Molding Sand at High Temperature

Stachowicz M., Paduchowicz P., Granat K.

Journal of Casting & Materials Engineering

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2017

|

Vol. 1, no. 3

64--69

EN

This paper discusses the impact of high temperatures (up to 900°C) on molding and core sand with inorganic binders selected from among the group of unmodified grades of hydrated sodium silicate (water-glass). Molding sands with medium quartz sand were made under laboratory conditions and compacted at the different energy inputs necessary for obtaining various apparent densities (ϱ0). Due to the different composition and apparent density of molding mixtures hardened via microwaves at a frequency of 2.45 GHz, it was possible to assess their deformation (L) at a high temperature above the binder’s eutectic temperature. For this purpose, an apparatus for hot distortion tests was used whose construction and equipment allows us to measure the thermoplastic deformations in molding sand in many aspects; i.e., in its time of annealing. The article proposes new possibilities of interpreting the hot distortion phenomena in comparative studies of molding materials and mixtures. The application of this new measurement method revealed the differences between molding mixtures made with five inorganic binders with a molar module ranging from 2.0 to 3.4 and apparent density ranging from 1.34 to 1.57 g/cm3. It was established that distortions under the influence of high temperatures last the longest in molding sand with a binder with the highest molar module (3.4). Research also revealed that the density of molding sand is significant for increasing/decreasing the rate of thermoplastic deformations following the heating of samples only if the molding sand includes binders with a molar module of between 3.0 to 3.4. For molding sand with binders with molar modules from 2.0 to 2.5, it was established that this is excessively susceptible to thermoplastic deformation.

20

Nowe stanowisko do badań elastyczności mas formierskich

Dobosz S. M., Grabarczyk A., Major-Gabryś K., Morek J.

Stal, Metale & Nowe Technologie

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2016

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nr 7-8

63--65

PL

W artykule przedstawiono opis nowego stanowiska do pomiaru odporności mas formierskich na odkształcenia mechaniczne (elastyczność) oraz termiczne (hot distortion). Szczegółowo wyjaśniono zasady pomiaru, sposób przygotowania próbek do badań oraz opis i interpretację otrzymanych wyników.

EN

The article describes a new measuring station focused on the resistance of molding sands to mechanical (elasticity) and thermal (hot distortion) deformation. The principles of the measurement, how to prepare the samples for testing, as well as the description and interpretation of the results, are explained in detail.