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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Evaluating the Factors Influencing the Friction Behavior of Paperboard during the Deep Drawing Process

Lenske, Alexander, Müller, Tobias, Penter, Lars, Schneider, Matti, Hauptmann, Marek, Majschak, Jens-Peter 28 June 2018 (has links)
Deep drawing of paperboard with rigid tools and immediate compression has only a small presence in the market for secondary packaging solutions due to a lack of understanding of the physical relations that occur during the forming process. As with other processes that deal with interactions between two solids in contact, the control of the factors that affect friction is important due to friction’s impact on runnability and process reliability. A new friction measurement device was developed to evaluate the factors influencing the friction behavior of paperboard such as under the specific conditions of the deep drawing process, which differ from the standard friction testing methods. The tribocharging of the contacting surfaces, generated during sliding friction, was determined to be a major influence on the dynamic coefficient of friction between paperboard and metal. The same effect could be examined during the deep drawing process. With increased contact temperature due to the heating of the tools, the coefficient of friction decreased significantly, but it remained constant after reaching a certain charging state after several repetitions. Consequently, to avoid ruptures of the wall during the forming process, tools that are in contact with the paperboard should be heated.
82

Analysis of Dominant Process Parameters in Deep-Drawing of Paperboard

Müller, Tobias, Lenske, Alexander, Hauptmann, Marek, Majschak, Jens-Peter 12 June 2018 (has links)
The application of the wrinkle measuring method described in Müller et al. (2017) and the subsequent evaluation algorithm of a range of deep-drawn samples were used to determine the influences and interdependencies of blankholder force, tool temperatures, and drawing height on the formation of wrinkles in paperboard. The main influences were identified and quantitatively evaluated. For the given experimental space, a regression function was derived and validated in further experiments. It was shown that a quadratic regression was superior to the previously used linear regression. The findings were discussed and compared with the results of similar experiments from past publications. Special attention was given to the wrinkles formed and the resulting quality of the formed paperboard cups. The restrictions of the data acquisition from the measuring method that was used and limitations of the model were presented to demonstrate the reliability of the results.
83

New Method to Evaluate the Frictional Behavior within the Forming Gap during the Deep Drawing Process of Paperboard

Lenske, Alexander, Müller, Tobias, Hauptmann, Marek, Majschak, Jens-Peter 22 May 2019 (has links)
To evaluate the influence of different normal forces and contact temperatures on the frictional behavior of paperboard during the deep drawing process, a new measurement punch was developed to measure the normal force, which induced the friction within the gap between the forming cavity and punch. The resulting dynamic coefficient of friction was calculated and reproduced via a new developed substitute test for the friction measurement device, which was first introduced in Lenske et al. (2017). The normal force within the forming gap during the deep drawing process was influenced by the blankholder force profile, the contact temperature, and the fiber direction. The friction measurements with the substitute test showed a strong dependency between the applied normal force and the dynamic coefficient of friction. Furthermore the frictional behavior was influenced by the contact temperature and the wrinkle formation.
84

Neue Einsatzpotentiale naturfaserbasierter Materialien in der Konsumgüterproduktion durch die technologische Entwicklung des Ziehverfahrens am Beispiel der Verpackung

Hauptmann, Marek 20 June 2017 (has links)
Die Produktion verschiedener Arten von Gütern ist im globalen Kontext gesellschaftlicher Entwicklung fortwährend an die Verfügbarkeit von Ressourcen gebunden und durch diese zunehmend begrenzt. In den bis heute entstandenen Wertschöpfungsketten basiert die verlustarme und effiziente Verteilung von Produkten, Zwischenprodukten, Halbzeugen sowie auch Rohstoffen auf den spezifisch auf die jeweiligen Erfordernisse eingestellten Funktionen ihrer Verpackungen. Als Bindeglied in nahezu allen Teilen der Produktion werden die Verpackung und ihre Herstellung innerhalb des mit Abstand größten Teils ihrer Anwendung, den Konsumgüterverpackungen als Beispiel für die Diskussion von Einsatzpotentialen naturfaserbasierter Materialien verwendet. Die Habilitationsschrift stellt die Ausgangssituation in der weltweiten Konsumgüterproduktion und Ressourcenverfügbarkeit dar und ordnet die Position naturfaserbasierter Packmittel in diese ein. Es werden Technologien zur Formgebung naturfaserbasierter Materialien zu Packmitteln zusammenfassend dargestellt. Die Ziehtechnik wird im Speziellen in Form eines Leitfadens in ihren Wirkmechanismen und Prozessvarianten sowie in Bezug auf ihre technische Umsetzung dargestellt. Es werden Beispiele konkreter Anwendungsmöglichkeiten diskutiert.
85

Neue Einsatzpotentiale naturfaserbasierter Materialien in der Konsumgüterproduktion durch die technologische Entwicklung des Ziehverfahrens am Beispiel der Verpackung

Hauptmann, Marek 20 June 2017 (has links)
Die Produktion verschiedener Arten von Gütern ist im globalen Kontext gesellschaftlicher Entwicklung fortwährend an die Verfügbarkeit von Ressourcen gebunden und durch diese zunehmend begrenzt. In den bis heute entstandenen Wertschöpfungsketten basiert die verlustarme und effiziente Verteilung von Produkten, Zwischenprodukten, Halbzeugen sowie auch Rohstoffen auf den spezifisch auf die jeweiligen Erfordernisse eingestellten Funktionen ihrer Verpackungen. Als Bindeglied in nahezu allen Teilen der Produktion werden die Verpackung und ihre Herstellung innerhalb des mit Abstand größten Teils ihrer Anwendung, den Konsumgüterverpackungen als Beispiel für die Diskussion von Einsatzpotentialen naturfaserbasierter Materialien verwendet. Die Habilitationsschrift stellt die Ausgangssituation in der weltweiten Konsumgüterproduktion und Ressourcenverfügbarkeit dar und ordnet die Position naturfaserbasierter Packmittel in diese ein. Es werden Technologien zur Formgebung naturfaserbasierter Materialien zu Packmitteln zusammenfassend dargestellt. Die Ziehtechnik wird im Speziellen in Form eines Leitfadens in ihren Wirkmechanismen und Prozessvarianten sowie in Bezug auf ihre technische Umsetzung dargestellt. Es werden Beispiele konkreter Anwendungsmöglichkeiten diskutiert.
86

Understanding The Impact Of Market demand For Paper And Paperboard On Swedish Ports : A scenario planning approach

Persson, Hanna, Bodiroga, Dejan January 2023 (has links)
Background: The global marketplace is characterized by rapid and constantchange, resulting in complex logistics systems. The port industry, which is a crucial link in the supply chain, seeks to understand the complexity of market dynamics. Ports should understand the changing market dynamics to better meet the market demand and have a competitive advantage. One representative from the port industry is Swedish ports and the Port of Gothenburg, which will be the focus of this thesis. The market demand for paper and paperboard has been a significant driver of shipping activities in Swedish ports. The market demand for bulk and container shipping is also relevant due to its influence on the port’s operation. Furthermore, itis essential for port authorities to understand the demand-oriented infrastructure to develop strategies to meet the market dynamics. Purpose: This thesis has been undertaken on behalf of the PoG. The purpose of the thesis is to provide a clearer understanding of how the current and future market demand of paper and paperboard influence Swedish ports with scenario planning. Based on the future market demand for paper and paperboard, additional information of the future market demand for bulk and container will be included in the scenarios. By using the scenarios, recommendations will be given regarding investments the port authority at PoG needs to implement as a response to future paper and paperboard market demand. Methodology: The thesis has a qualitative case study with Port of Gothenburg as the study object. Data collection has been conducted through semi- and unstructuredinterviews from the Swedish forest industry, three forest companies and port authority at Port of Gothenburg. Additionally, scenario planning will be the main analysis method in this thesis. Conclusion: The current market demand for paper and paperboard indicates that demand for paper is decreasing, while demand for paperboard is increasing. The future market demand for paper and paperboard can develop in several ways. The authors of this thesis believe that the market demand for paper will have a structural fall with an exception for special paper. While paperboard will have a continuous increase. Furthermore, there is currently an increase of bulk and container shipping in the Port of Gothenburg. The authors believe that future market demand for bulk will be stable, while container will have an increased trend. However, as the market demand is hard to predict, the thesis presents four scenarios of different futureoutcomes of market demand for paper, paperboard, bulk- and container shipping. There are several investments needed for the Port of Gothenburg to respond to theestablished demand scenarios. Investments that will benefit Port of Gothenburg themost are Port Community System (PCS), Integrated Warehouse ManagementSystem (IWMS), Real-Time Location System (RTLS), development of port quays,larger quay cranes and floating islands, and cold ironing and renewable energy. Key words: Paper, Paperboard, forest industry, bulk, container, cargo shipping,seaport, Port of Gothenburg, scenario planning, port investments
87

Sugarcane juice extraction and preservation, and long-term lime pretreatment of bagasse

Granda Cotlear, Cesar Benigno 17 February 2005 (has links)
New technologies, such as an efficient vapor-compression evaporator, a stationary lime kiln (SLK), and the MixAlco process, compelled us to re-evaluate methods for producing sugar from cane. These technologies allow more water and lime to be used, and they add more value to bagasse. Extracting and preserving the sugars, and lime pretreating the bagasse to enhance biodigestibility, all at the same time in a pile, was demonstrated to be unfeasible; therefore, sugar extraction must occur before lime treating the bagasse. Sugar extraction should occur countercurrently by lixiviation, where liquid moves in stages opposite to the soaked bagasse (megasse), which is conveyed by screw-press conveyors that gently squeeze the fiber in each stage, improving extraction. The performance of a pilot-scale screw-press conveyor was tested for dewatering capabilities and power consumption. The unoptimized equipment decreased megasse moisture from 96 to 89%. Simulation of the process suggested that eight stages are necessary to achieve 98% recovery from typical sugarcane. The cumulative power for the screw-press conveyor system was 17.0±2.1 hp•h/ton dry fiber. Thin raw juice preserved with lime for several months showed no sucrose degradation and no quality deterioration, except for reducing sugar destruction. The lime loading needed for 1-year preservation is 0.20 g Ca(OH)2/g sucrose. Shorter times require less lime. After preservation, the juice was carbonated and filtered, and the resulting sludge pelletized. Due to their high organic content, the pellets were too weak for calcination temperatures used in the SLK. The organics must be decreased prior to pelletization and sodium must be supplemented as a binding agent. Long-term lime pretreatment of bagasse showed two delignification phases: bulk (rapid) and residual (slow). These were modeled by two simultaneous first-order reactions. Treatments with air purging and higher temperatures (50 – 57oC) delignified more effectively, especially during the residual phase, thus yielding higher cellulase-enzyme digestibilities after 2 – 8 weeks of treatment. At temperatures > 60oC, pure oxygen purging is preferred. Fresh bagasse was of better quality than old bagasse. Treatment with NaOH yielded a larger bulk delignification phase than Ca(OH)2. Long-term lime pulping of bagasse was unsuitable for copy-quality paper, but it was appropriate for strawboard and other filler applications.
88

Undersökning av mekaniska egenskaper hos sandwichelement av core-materialet Greenwood och ytskikt av papp : Styvhet, bärförmåga samt elementens beteenden vid belastning för olika tjocklekar på ytskikten / Examination of mechanical properties of sandwich panels made of the core-material Greenwood and surface layers of paperboard : Stiffness, ultimate capacity and structural behavior for different surface layer thicknesses

Nilsson, Maxim January 2023 (has links)
Byggbranschens utsläpp av växthusgaser utgör en stor andel av Sveriges totala utsläpp. För att minska de byggrelaterade utsläppen är det på många fronter som byggbranschen behöver förändras och effektiviseras. De senaste åren har en succesiv ökning av byggandet i trä skett vilket är gynnsamt då trä alternativet är mer klimatvänligt än stål och betong. De tuffa klimatmålen vi nu står framför innebär dock att mer behöver göras än att endast öka andelen träbyggnader. Pappersmassaindustrin är lätt att bortse ifrån, då den hittills inte varit relevant för byggbranschen och för att återanvändning är relativt framträdande inom den branschen. Ifrån sågverken som sönderdelar trästockar till virke fraktas flis som blir över till pappersbruk. Av flisen görs sedan bland annat diverse pappförpackningar som går att återvinna. Problemet är att dessa förpackningar endast går att återvinna ett visst antal gånger innan fibrerna blir obrukbara och istället används som biobränsle. Om byggmaterial skulle gå att producera baserat på dessa fibrer, skulle detta innebära en mer långlivad användning av dem. Ett byggmaterial som uppfunnits, gjort på fibrer från pappersmassabruk är core-materialet ”Greenwood”. Eftersom materialet är nytt och egenskaperna till stor del är okända krävs det att diverse studier görs som undersöker materialets olika egenskaper som är relevanta för en eventuell tillämpning inom byggbranschen. Denna studie avser att undersöka skjuvstyvhet, böjstyvhet och bärförmåga hos sandwichelement uppbyggda av core-materialet Greenwood och ytskikt av papp. Detta genom att först  dynamiskt och statiskt testa de ingående materialens egenskaper, följt av böjprovning av nio sandwichbalkar med varierande tjocklek på ytskikten. Samtliga balkar testades även dynamiskt. Core-materialet Greenwood som ingick i sandwichelementen var endast den begränsande faktorn en gång av tio böjprov. När core-materialets skjuvstyvhet togs fram både dynamiskt och statiskt och när den omvandlades till en skjuvmodul visade det sig att Greenwood har en mer än dubbelt så stor styvhet som EPS-cellplast vid liknande densitet. Detta är intressant då denna cellplast ofta agerar som ett core-material i sandwichelement ute i byggbranschen. Testerna visar även på att balkarna har en relativt liten spridning vilket innebär att resultaten har god tillförlitlighet. Slutligen, kan det konstateras att dessa sandwichelement uppvisar sega egenskaper med en viss kvarvarande lastkapacitet även efter brott. Samtliga nämnda egenskaper ovan talar för en viss potential för tillämpning av dessa sandwichelement inom byggbranschen. Fortsatta studier av fukt- och krypegenskaper vid långtidsbelastning rekommenderas, vilket är viktigt för användning inom byggandet. De omfattande resultaten från föreliggande studie utgör dock ett bra underlag för fortsatta undersökningar och värdering av möjliga tillämpningar. / The construction industry`s greenhouse emissions, makes up for a large portion of Sweden’s total emissions. In order to reduce construction related emissions, a fair amount of fronts within the construction industry needs to be changed and streamlined. In the last couple of years, there has been a successive increase in the number of structures that are built from wood amongst other things, which is beneficial because the wood alternative is more climate friendly than steel and concrete. The current tough climate goals entails that more has to be done than just increasing the amount of wood constructions. The pulp industry is easy to write off because so far, it has not been relevant to the construction industry and because recycling is relatively prominent within that industry. From the sawmills that dismember wooden logs to lumber, leftover wood chips are transported to paper mills. Among other things, different cardboard packages that can be recycled are then made from those wood chips. The problem with these packages is that they can only be recycled a certain number of times before the fibers become unusable and instead, are used as biofuel. If building materials were to be able to be produced with these fibers, that would be a more long-lived use of them. A building material, recently invented, made of fiber from paper mills is the core-material “Greenwood”. Because the material is new and its properties for the most part are unknown, this requires that various studies are conducted that examines the different properties the material possesses that are relevant for a contingent enforcement within the construction industry. This study intends to examine the shear rigidity, flexural rigidity and maximum capacity for sandwich panels made from the core-material Greenwood and faces of paperboard. This was achieved by first dynamically and statically test the properties of the two different materials, followed by flexure testing nine sandwich beams with varying face thicknesses. Every beam was also tested dynamically. The core-material Greenwood which was a part of the sandwich panels, was only the limiting factor 1 time out of 10 flexure tests. When the shear rigidity of the core-material was calculated both statically and dynamically and when it was converted to a shear modulus it was shown that Greenwood has a rigidity of more than double that of EPS cellular plastic at similar density. This is interesting because this type of cellular plastic often acts as a core-material in sandwich structures found in the construction industry. The tests also show that the beams have a relatively small spread which means that the results have good reliability. Finally, it can be concluded that these  sandwich panels exhibit ductile properties with a certain lasting load capacity even after ultimate load has been reached. Every property mentioned above indicates that there is a certain potential for applicability of these sandwich panels within the construction industry. Continued studies of moisture properties and creep properties during long-term loading is recommended, which is important for a possible use within construction. The extensive results from this study constitutes a good basis for continued research and assessment of possible applications.

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