Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 17

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  thermoforming
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
EN
The objective of the study was to present the results of research on the thermoforming process using a patented, original male mold vibrating with the adequate frequency during the stretching of a polystyrene sheet. The research included determining the influence pertaining to the frequency of the mold vibration as well as other selected conditions of the thermoforming process, such as the temperature of the heater and heating time on the irregularity of the wall thickness of the formed product. The research was conducted using the DOE methods – central composite design. The thermoforming process was conducted using the vacuum stretching method with initial forming by high-pressure air. The analysis of the results obtained showed that the frequency of mold vibration has a significant statistic influence on the thickness of the walls of a finished product, both in the area of their bottom as well as the bottom’s edge. The thickness of the product wall on these areas is also significantly influenced by the other above-mentioned factors. No interaction, however, was detected between those and the frequency of the mold vibration. Using the vibrating mold in the presented process proved favourable, since the walls of the obtained finished products showed lesser irregularity in terms of the wall thickness than the products manufactured using a fixed mold.
EN
The paper describes a utility function – based method for optimization of a thermoforming process for producing finished parts made of polystyrene sheet by vacuum forming and vacuum assisted drape forming with and without pre-blow. Not only does the proposed method enable determination of optimum thermoforming conditions, it also provides information about interactions between these conditions as well as about their impact on the properties of finished parts and polymer heating time, a factor which affects efficiency of this process. The determined optimum thermoforming conditions significantly differ for thermoforming without pre-blow and thermoforming with pre-blow, which results from different ways of forming individual regions of polystyrene sheet during both processes. The employed method enables determination several optimum criteria, the number of which can be extended as desired, which is significant for practical applications of machines and devices.
PL
W pracy przedstawiono metodykę optymalizacji z wykorzystaniem funkcji użyteczności na przykładzie procesu termoformowania. Optymalizacji wielokryterialnej poddano proces termoformowania kształtek z folii polistyrenowej metodą próżniowego rozciągania stemplowego, bez rozdmuchiwania wstępnego oraz z rozdmuchiwaniem wstępnym. Zaprezentowana metoda umożliwia wyznaczenie optymalnych warunków termoformowania, poszerza również wiedzę w zakresie ich wzajemnych korelacji i siły wpływu na właściwości otrzymywanych kształtek oraz czas nagrzewania folii, determinujący wydajność tego procesu. Wyznaczone optymalne wartości parametrów termoformowania w istotnym stopniu różnią się w wypadku procesu bez rozdmuchiwania wstępnego i z jego zastosowaniem, co jest następstwem odmiennego przebiegu rozciągania poszczególnych obszarów folii w obu procesach. Wykorzystana metoda pozwala na poszukiwanie optimum uwzględniającego wiele cech – kryteriów jednocześnie, które ponadto można rozszerzać w zależności od potrzeb, co ma duże znaczenie w praktycznych zastosowaniach eksploatacyjnych maszyn i urządzeń.
EN
Purpose: Dysfunctions of the stomatognathic system are treated with a lot of appliances. The aim of the work was to evaluate the current state in the field of diagnostic techniques and technological advance in appliances and materials enhancing therapy of occlusion disorders of the stomatognathic system. Design/methodology/approach: The principles of appliances functioning, manufacturing technology and materials were analysed. The analysis was made on the basis of the literature review and patent databases, conducting searches for a combination of keywords: dental material, occlusion, disorder, bruxism, clenching, grinding, appliance, therapy, tongue, oral, exerciser, trainer, mandible muscle, bite splint, dental plate. In the case of principles of functioning, devices that require insertion into the mouth are included in the tests. In technology and materials, attention has been paid to necessity of involving a dental technician or ability to perform appliance intra-orally ("chairside"), as well as mass production with possibility of custom fit. Findings: The most widespread in the treatment of disorders of the stomatognathic system are thermoformed materials and devices that are introduced between the dental arches to counteract occlusions of all teeth or selected teeth or force the position of the mandible in relation to the maxilla. Devices that function differently are those in which therapeutic effects result from toning of activity of the elevating mandibular muscles by provoking activity of the opposing muscles lowering the mandible or reducing intra-oral space, for example, by sublingual plates or tongue trainers. Appliances are mainly manufactured of: poly (ethylene- vinyl acetate) or polycarbonates, as also mouldable polymers such as: acrylics, polyesters and rubbers. Research limitations/implications: Electronic devices that are not intended to therapy but used only to track mandible mobility or muscle activity during sleep were not taken into account. Practical implications: Solutions activating the action of the opposing muscles to the muscles lifting the mandible are few, and among them one device is retained on teeth without interfering in occlusion. Originality/value: Dental materials for dev/ices for treatment of occlusion disorders are selected with no understanding tines influence of elastic and frictional material properties and structures stiffness on the distribution of occlusion forces between the teeth and reactions in temporo-mandibular joints.
EN
Purpose: Dysfunctions of the stomatognathic system are treated with a lot of appliances. The aim of the work was to evaluate the current state in the field of diagnostic techniques and technological advance in appliances and materials enhancing therapy of occlusion disorders of the stomatognathic system. Design/methodology/approach: The principles of appliances functioning, manufacturing technology and materials were analysed. The analysis was made on the basis of the literature review and patent databases, conducting searches for a combination of keywords: dental material, occlusion, disorder, bruxism, clenching, grinding, appliance, therapy, tongue, oral, exerciser, trainer, mandible muscle, bite splint, dental plate. In the case of principles of functioning, devices that require insertion into the mouth are included in the tests. In technology and materials, attention has been paid to necessity of involving a dental technician or ability to perform appliance intra-orally ("chairside"), as well as mass production with possibility of custom fit. Findings: The most widespread in the treatment of disorders of the stomatognathic system are thermoformed materials and devices that are introduced between the dental arches to counteract occlusions of all teeth or selected teeth or force the position of the mandible in relation to the maxilla. Devices that function differently are those in which therapeutic effects result from toning of activity of the elevating mandibular muscles by provoking activity of the opposing muscles lowering the mandible or reducing intra-oral space, for example, by sublingual plates or tongue trainers. Appliances are mainly manufactured of: poly (ethylenevinyl acetate) or polycarbonates, as also mouldable polymers such as: acrylics, polyesters and rubbers. Research limitations/implications: Electronic devices that are not intended to therapy but used only to track mandible mobility or muscle activity during sleep were not taken into account. Practical implications: Solutions activating the action of the opposing muscles to the muscles lifting the mandible are few, and among them one device is retained on teeth without interfering in occlusion. Originality/value: Dental materials for dev/ices for treatment of occlusion disorders are selected with no understanding the influence of elastic and frictional material properties and structure stiffness on the distribution of occlusion forces between the teeth and reactions in temporo-mandibular joints.
EN
The paper reports the results of a study on the effect of selected conditions in a thermoforming process for thin polystyrene sheet by vacuum assisted drape forming on the wall thickness non-uniformity of finished parts. The investigation was performed using Statistica’s DOE module for three variables: temperatures in the external and internal zones of the heater as well as heating time of the plastic sheet. The results demonstrate that the wall thickness in the finished parts at the measuring points is primarily affected by the heating time and the temperature in the internal zone of the heater, while the temperature in the external zone only affects some regions of the finished part. The results demonstrate that a short heating time, and hence, a lower temperature of the plastic sheet lead to a more uniform deformation of both the bottom and the side walls of the finished part, and as a consequence, to smaller variations in the wall thickness. Shortening the heating time is, however, limited by the necessity of accurate reproduction of the shape of the finished part.
EN
In this study, cylindrical, conical and hemispherical molds were used to form flat thermoplastic sheets which are 1.5 mm in thickness. The effect of plug assist on thickness distribution was investigated. The sheets were formed with and without plug assist. Then thickness distributions on thermoformed products were obtained for two experimental procedures by a digital caliper (Resolution: 0.01 mm). As a result, plug assist thermoforming provides more uniform thickness distributions than negative forming.
EN
In this work, Polystyrene (PS) sheets were thermoformed in predetermined conditions. Wall thickness distributions obtained by experimental method in PS thermoformed products. Then the same thickness distributions were predicted by using Geometric Element Analysis (GEA). The thickness results were obtained experimentally, compared to thickness distributions which were predicted by GEA. It has been found that GEA does not precisely reveal thickness distributions.
EN
The paper reports the results of a study on the effect of selected conditions of a pressure-bubble vacuum forming for polystyrene sheet on the non-uniformity of wall thickness of finished parts. The investigation was performed using DOE methods. Variables for the tests included temperatures in the external and internal zones of the heaters as well as heating time. The results demonstrate that the heating time and temperature in the internal zone formed by the heater have a statistically significant effect on the finished part’s wall thickness at the measuring points. It has been found that the side walls and bottom of the finished part are uniformly deformed, and thus exhibit the lowest wall thickness non-uniformity at a heating time of 22s (corresponding to the middle of the measuring range). Also, it is observed that the application of low temperatures in both zones of the heater has a positive effect. Due to the use of bubble, the finished parts exhibit a much lower wall thickness non-uniformity compared to those produced without bubble.
PL
W pracy przedstawiono technologie stosowane do wytwarzania zbiorników i pojemników (zwłaszcza wielkogabarytowych) z tworzyw polimerowych. Omówiono klasyfikację metod ich wytwarzania. Klasyfikacji dokonano w oparciu o kryteria przeznaczenia zbiorników, rodzaj zastosowanego tworzywa i wynikającej z tego technologii. Ponadto opisano zagadnienia dotyczące studzienek z tworzyw.
EN
This paper presents the technologies used in the manufacture of tanks and containers (especially large size) of polymeric materials. The classification of methods of their manufacture has been presented. Classification was based on the criteria of destination containers, the type of material used and the resulting technology. Furthermore, it describes the issues relating to the wells from plastic.
PL
Opisano stanowisko badawcze SB420 zaprojektowane w celu prowadzenia badań procesów termoformowania tworzyw termoplastycznych oraz optymalizacji procesów termo formowania opakowań realizowanych na rolowych maszynach pakujących. Wyznaczono rozkłady grubości ścianek na przykładzie próżniowo wyformowanych opakowań o różnej głębokości, dla których przeprowadzono symulację MES. Pokazano nierównomierność grubości, w tym miejsca potencjalnie najcieńsze, które ograniczają kształtowalność wyrobu.
EN
Presented in the article is thermoforming device SB420 which was designed for thermoplastic materials research and optimization thermoforming process implemented especially on roll fed packing machines. Wall thickness distribution of thermoformed parts with different depth was determined. FEM analysis showed thickness variation and minimum part thickness which cause thermoforming limits.
11
Content available remote Tworzywa polimerowe do rozciągania próżniowego i ich właściwości
PL
Znajomość podstawowych wiadomości na temat kształtowanych materiałów i ich właściwości jest niezbędna zarówno dla producentów maszyn do rozciągania próżniowego jak i ich odbiorców w tym dla personelu obsługi maszyn. W artykule krótko przedstawiono istotę rozciągania próżniowego wraz z jego zaletami i wadami, oraz przedstawiono podstawowe właściwości tworzyw polimerowych istotnie wpływające na poprawność procesu rozciągania próżniowego, jak: temperatura tworzywa, sztywność, orientacja, tarcie, skurcz, zachowanie podczas nagrzewania i chłodzenia, oraz kształtowanie w formie.
EN
Knowledge of basic information about the thermoforming materials and their properties is necessary both for the manufacturers of thermoforming machines and their customers including personnel operating machinery. The article briefly presents the essence of stretching the vacuum with the advantages and disadvantages, and presents the basic properties of polymeric materials significantly affect of the thermoforming, as the temperature of the material, rigidity, orientation, friction, shrinkage, the behavior during heating and cooling, and shaping in the form.
12
Content available remote Functional graded self-reinforced polypropylene sheets
EN
Self-reinforced polypropylene composites (SR-PP) combine exceptional mechanical properties with an impressive light-weight construction potential and good recycling qualities. This paper focuses on the description of the structural composition and the potential of self-reinforced polypropylene sheets. First of all, the functionality of self-reinforcement is specifically illustrated. The performance of SR-PP sheets in comparison to conventionally reinforced fibre composites is highlighted. In order to gain basic knowledge of SR-PP composites, the processing technology is illustrated in detail. The consolidation process significantly influences the self-reinforcement and, consequently, the final property composition of the SR-PP sheets. Based on the requirements regarding component application, the challenges in transferring the material technology to application series are outlined. Thermo-mechanical gradation provides a good approach to solving the problem of depicting complex demand profiles in order to enable economic viability in broad fields of application. Functional gradation significantly influences the mechanical properties of SR-PP sheets locally, thus, making it possible to produce impact strengths and consistencies compatible adjusted to the component functions.
PL
Artykuł stanowi przegląd literaturowy dotyczący samowzmocnionych kompozytów polipropylenowych (SR-PP) wykazujących wyjątkowe właściwości mechaniczne (tabela 1, rys. 2, 7) w połączeniu z niezwykłą lekkością konstrukcji oraz łatwością recyklingu. Opisano budowę strukturalną i potencjalne możliwości aplikacji samowzmocnionych płyt polipropylenowych. Szczegółowo omówiono proces funkcjonalnego, gradientowego samowzmacniania polipropylenowych płyt (tabela 2, rys. 3-6), wskazując na zasadniczy jego wpływ na właściwości końcowego produktu i porównano metody wytwarzania SR-PP z metodami otrzymywania tradycyjnych kompozytów wzmacnianych włóknami. Scharakteryzowano możliwości zastosowania samowzmocnionych płyt PP wykorzystujące specyficzne cechy tak uzyskiwanego materiału.
13
Content available remote Projekt koncepcyjny urządzenia do termoformowania tworzyw sztucznych
PL
Opisano projekt koncepcyjny maszyny do termoformowania próżniowego tworzyw termoplastycznych do produkcji jednostkowej elementów o wielkości 400x400x350 mm. Ma Byron zbudowany i używany przez studentów Wydziału Samochodów i Maszyn Roboczych Politechniki Warszawskiej. Projekt, który zakładał użycie tanich i szeroko dostępnych materiałów, został wykonany w inżynierskim systemie 3D CAD.
EN
The article informs about project of vacuum thermoforming machinery to plastic parts. This device could be used to manufacturing low series parts about size 400x400x350mm. This project will be built and will be used by students from Warsaw University of Technology. The machinery was designed in environment engineering system 3D CAD.
EN
Thermoforming is a manufacturing process widely used to produce thin thermoplastic parts from small blister packs to display AAA size batteries to large skylights and aircraft interior panels. In this paper was presented numerical simulation of the inflation phase of a thermoforming process under which a thin polymer sheet is deformed into a mould under the action of applied pressure. Two cases of blowing sheet were considered. In the first, preapproved on the basis of a constant sheet temperature (T = 150°C) examined the distribution of the container wall thickness. There has been excessive thinning (about 0,2mm) in the cup corners after forming. Also simulation it was made for other constant temperature (160, 170, 180, 190 and 200°C). On this basis, was made optimization of the sheet profile temperature (in range 150÷200°C) to remove excessive thinning. Noted was a significant effect of the initial sheet temperature distribution on the final wall thickness distribution in the considered container. The Ansys Polyflow procedure of optimizing the sheet temperature distribution allowed eliminating excessive thinning in the considered cup walls corners.
15
Content available remote Wybrane problemy termoformowania materiałów polimerowych
PL
Na podstawie obszernego przeglądu literatury przedstawiono syntetycznie zebrane najważniejsze problemy związane z termoformowaniem materiałów polimerowych. Ogólnie scharakteryzowano proces i wykorzystywane w nim tworzywa polimerowe. Omówiono podstawowe rodzaje termoformowania tj. negatywowe, pozytywowe i dwupłytowe. Zaprezentowano wyniki badań pochodzące z najnowszych publikacji dotyczących zagadnień związanych z termoformowaniem, mianowicie wpływu struktury materiału polimerowego na efekt termoformowania, wpływu dodatku włókien wzmacniających do kompozytu polimerowego na jego wytrzymałość mechaniczną w stanie wysokoelastycznym, metod modelowania procesów termoformowania oraz sposobów ogrzewania materiału polimerowego.
EN
The most important developments and problems encountered in the thermoforming of polymeric materials have been presented based on a comprehensive review of the literature. The process, as well as the most suitable polymers in its applications have been characterized in general. The basic types of thermoforming - negative (Figs. 2 and 4), positive (Figs. 5 and 6) and twin-sheet methods were discussed. The results of the most recent studies presented in publications related to thermoforming such as the influence of the type of polymeric material on thermoforming, the effect of reinforcing fibers added to the polymeric composite on its mechanical resistance in the high-elastic state, thermoforming modeling methods and also thermal treatment methods of the polymeric material.
16
Content available remote Thermoforming of polylactide nanocomposite films for packaging containers
EN
Experimental results of thermoforming of two kinds of polylactide containers of similar capacity but differing in shape were used to determine the basic parameters of this process. The films made of both pure polylactide or polylactide nanocomposites, the latter including a montmorillonite nanofiller (5 wt. %) and poly(ethylene glycol) (10 wt. %) or poly(methyl methacrylate) (10 wt. %), were applied to forming these containers. These three kinds of films were 250 or 400žm thick. It was found that the containers could be thermoformed in the temperature range of 75-90° and that the film thickness affected the dispersion of the container wall thicknesses. Thus, it has been confirmed that a thorough experimental study is necessary before the manufacturing of a specific type of container thermoformed from pure polylactide or its nanocomposites could be implemented. The study should be aimed mainly at a reduction in the dispersion of the container wall thickness.
PL
Na podstawie wyników badań określono główne parametry procesu termoformowania dwóch typów pojemników polilaktydowych o różnych kształtach i zbliżonej objętości. Do wytwarzania tych pojemników zastosowano folię polilaktydową oraz folie z nanokompozytu polilaktydowego zawierającego 5 % mas. nanonapełniacza montmorillonitowego i 10 % mas. glikolu poli(oksy)etylenowego lub 10 % mas. poli(metakrylanu metylu). Badane pojemniki wytwarzano z tych trzech rodzajów folii o dwóch różnych grubościach wynoszących 250 lub 400žm. Stwierdzono, że te pojemniki można termoformować w temperaturach od 75 do 90°. Zauważono wpływ grubości zastosowanych folii na rozrzut grubości ścianek pojemników. Tym samym potwierdzono konieczność przeprowadzania, przed wdrożeniem do produkcji konkretnego typu pojemnika termoformowanego z polilaktydu lub z jego nanokompozytów, szczegółowych badań eksperymentalnych, których głównym celem byłoby dobranie warunków procesu dających zmniejszenie rozrzutu grubości ścianek pojemnika.
PL
W artykule przedstawiono wpływ pochłoniętej wody przez płyty koekstrudowane Senosan na ich mechaniczne i elektryczne właściwości. Określono ich nasiąkliwość oraz wykonano próbę statycznego rozciągania próbek o zawartości wody: 0%, 0,25% i 0,5%. Dokonano analizy wpływu zawartej wody w tworzywie na jego wytrzymałość na rozerwanie, granicę plastyczności oraz wartość przenikalności elektrycznej względnej.
EN
In the paper, the authors showed the influence of water absorbed by Senosan plates on their mechanical and electric properties. Their absorbability was determined and a static stretching test was performed for the samples of 0%, 0,25% and 0,5% water. The influence of material water content on its tearing strength, yield point and relative permittivity was analyzed, as well.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.