Kiinnirullaimen dynamiikan ja v��r��htelyjen simulointi

Diplomity��ss�� tutkittiin kaupallisen monikappaledynamiikkaohjelmiston soveltuvuutta kiinnirullaimen dynamiikan ja v��r��htelyjen tutkimiseen. Erityisen kiinnostuneita oltiin nipin kuvauksesta sek�� nipiss�� tapahtuvista v��r��htelyist��. T��ss�� diplomity��ss�� mallinnettiin kiinnirullaimen ensi��- ja toisiok��yt��t sek�� tampuuritela. Malli yhdistettiin my��hemmin Metso Paper J��rvenp����ss�� rinnakkaisena diplomity��n�� tehtyyn malliin, joista muodostui kahteen ratkaisijaan perustuva simulointimalli. Simulointimalli rakennettiin k��ytt��m����n kahta erillist�� ratkaisijaa, joista toinen on mekaniikkamallin rakentamisessa k��ytetty ADAMS-ohjelmisto ja toinen s����t��j��rjestelm���� ja hydraulipiirej�� kuvaava Simulink-malli. Nipin mallintamiseksi tampuuritela ja rullaussylinteri mallinnettiin joustaviksi k��ytt��en keskitettyjen massojen menetelm����. Siirtolaitteissa sek�� runkorakenteissa tapahtuvat joustot kuvattiin yhden vapausasteen jousi-vaimennin voimilla kuvattuina j��rjestelmin��. T��ss�� diplomity��ss�� on my��s keskitytty esittelem����n ADAMS-ohjelmiston toimintaa ohjeistavasti sek�� k��sittelem����n parametrisen mallintamisen etuja. Ty��ss�� havaittiin monikappaledynamiikan soveltuvuus kiinnirullaimen dynamiikan sek�� dynaamisten voimien aiheuttamien v��r��htelyjen tutkimiseen. Suoritetuista v��r��htelymittauksista voitiin tehd�� vain arvioita. Mallin havaittiin vaativan lis��tutkimusta ja kehitysty��t��

Development of rotating drum under mechanical and thermal load

A variable temperature field sets exacting demands to the structure under mechanical load. Most of all the lifetime of the rotating drum structure depends on temperature differences between parts inside the drum. The temperature difference was known because of the measurements made before. The list of demands was created based on customers��� needs. The limits of this paper were set to the inner structure of the drum. Creation of ideas for the inner structure was started open minded. The main principle in the creation process was to create new ideas for the function of the product with the help of sub-functions. The sub-functions were created as independent as possible. The best sub-functions were combined together and the new working principles were created based on them. Every working principle was calculated separately and criticized at the end of the calculation process. The main objective was to create the new kind of structure, which is not based too much to the old, inoperative structure. The affect of own weight of the inner structure to the stress values was quite small but it was also taken into consideration when calculating the maximum stress value of the structure. Because of very complex structures all of the calculations were made with the help of the ProE ��� Mechanica software. The fatigue analyze was made also for the best structure solution.

Purchasing Process Performance Definition and Improvement in the Mechanical Wood Industry

T��m��n tutkimuksen ensisijaisena tavoitteena oli m����ritt���� Schauman Wood Oy:n ostoprosessin suorituskyvyn nykytila yrityksen Suomen yksik��iss��. Nykytila-arviointi suoritettiin uusien ja k��yt��ss�� olevien mittaustulosten avulla. Tutkimuksessa verrattiin kymmenen tuotantolaitoksen ostoprosesseja kesken����n. Keskeinen tutkimusongelma oli ostoprosessin suorituseroja aikaansaavien tekij��iden selvitt��minen eri yksik��iss��. Tutkimuksen tavoitteena oli saavuttaa yhten��isemm��t toimintatavat yrityksess�� sek�� laajentaa konsernin osto-organisaation hy��dynt��mist�� hankintatoimessa. Tavoitteena oli ostoprosessin virtaviivaistaminen ja tehokkaamman seurantaj��rjestelm��n kehitt��minen. Ostotoimintojen suorituskyvyn jatkuva parantaminen perustuu osittain uusien mittareiden avulla saatavaan informaatioon ja t��sm��llisemp����n seurantaan. Sis��ist�� benchmarkingia k��ytettiin ty��kaluna suorituskyky-eroavaisuuksien m����rittelyss��. Tietoa erilaisista toimintatavoista ker��ttiin haastattelemalla yrityksen ostajia ja tehdaspalvelup����llik��it�� eri tehdaspaikkakunnilla. Sis��isen benchmarkingin avulla m����riteltiin toimintatapa eroavaisuudet sek�� kehitettiin seurantakortti, jossa jokaista yksikk���� verrataan parhaaseen ja eniten kehittyneeseen yksikk����n. Ty��n tuloksina muodostui ehdotuksia ostotoiminnon uusiksi mittareiksi. Uudet mittarit ovat tehokkuusmittareita, jotka kuvaavat resurssien k��yt��n tehokkuutta sek�� auttavat seuraamaan ostoprosessin tilaa entist�� paremmin. Uusien mittareiden tavoitteena on my��s v��hent���� mittareiden manipulaatiomahdollisuutta. Ty��n ulkopuolelle rajattiin informaatioteknologiaj��rjestelmien tietotekninen osuus. Er��s yrityksen tuotantolaitoksista rajattiin my��s ty��n ulkopuolelle, koska sen ostoprosessit ovat huomattavasti kehittym��tt��m��mpi�� kuin Schauman Woodin muiden tehtaiden ostoprosessit. Kyseisen yksik��n kehitt��misen tulee l��hte�� aivan ruohonjuuritasolta. Tutkimuksen teoriaosuus on ker��tty alan ammattikirjallisuudesta ja tutkimuksen aihetta k��sittelevist�� uudehkoista tieteellisist�� alan artikkeleista. Teorian tarkoituksena on tukea empiirist�� osuutta sek�� antaa lukijalle uusia n��kemyksi�� ostotoiminnan monista mahdollisuuksista. Tutkimuksen tuloksia ovat nykytila-analyysi, ehdotukset uusista ostotoiminnan mittareista sek�� ehdotus MRO-tuotteiden ulkoistamiskokeilusta. Yrityksen ostotoiminnan tulisi kehitty�� operatiivisesta tasosta kohti strategisempaa oston tasoa. Johdon sitoutuminen hankintatoimen kehityshankkeisiin on erityisen t��rke����, lis��ksi hankintatoimi tulisi n��hd�� strategisempana osa-alueena yrityksess��. Hankintatoimen kehitt��misen avulla yrityksen kustannustehokkuutta voidaan lis��t�� merkitt��v��sti.

On the Analysis and Control of a Linear Synchronous Servomotor with a Flexible Load

Industry's growing need for higher productivity is placing new demands on mechanisms connected with electrical motors, because these can easily lead to vibration problems due to fast dynamics. Furthermore, the nonlinear effects caused by a motor frequently reduce servo stability, which diminishes the controller's ability to predict and maintain speed. Hence, the flexibility of a mechanism and its control has become an important area of research. The basic approach in control system engineering is to assume that the mechanism connected to a motor is rigid, so that vibrations in the tool mechanism, reel, gripper or any apparatus connected to the motor are not taken into account. This might reduce the ability of the machine system to carry out its assignment and shorten the lifetime of the equipment. Nonetheless, it is usually more important to know how the mechanism, or in other words the load on the motor, behaves. A nonlinear load control method for a permanent magnet linear synchronous motor is developed and implemented in the thesis. The purpose of the controller is to track a flexible load to the desired velocity reference as fast as possible and without awkward oscillations. The control method is based on an adaptive backstepping algorithm with its stability ensured by the Lyapunov stability theorem. As a reference controller for the backstepping method, a hybrid neural controller is introduced in which the linear motor itself is controlled by a conventional PI velocity controller and the vibration of the associated flexible mechanism is suppressed from an outer control loop using a compensation signal from a multilayer perceptron network. To avoid the local minimum problem entailed in neural networks, the initial weights are searched for offline by means of a differential evolution algorithm. The states of a mechanical system for controllers are estimated using the Kalman filter. The theoretical results obtained from the control design are validated with the lumped mass model for a mechanism. Generalization of the mechanism allows the methods derived here to be widely implemented in machine automation. The control algorithms are first designed in a specially introduced nonlinear simulation model and then implemented in the physical linear motor using a DSP (Digital Signal Processor) application. The measurements prove that both controllers are capable of suppressing vibration, but that the backstepping method is superior to others due to its accuracy of response and stability properties.

Validation of plant dynamic model by online and laboratory measurements ��� a tool to predict online COD loads out of production of mechanical printing papers

COD discharges out of processes have increased in line with elevating brightness demands for mechanical pulp and papers. The share of lignin-like substances in COD discharges is on average 75%. In this thesis, a plant dynamic model was created and validated as a means to predict COD loading and discharges out of a mill. The assays were carried out in one paper mill integrate producing mechanical printing papers. The objective in the modeling of plant dynamics was to predict day averages of COD load and discharges out of mills. This means that online data, like 1) the level of large storage towers of pulp and white water 2) pulp dosages, 3) production rates and 4) internal white water flows and discharges were used to create transients into the balances of solids and white water, referred to as ���plant dynamics���. A conversion coefficient was verified between TOC and COD. The conversion coefficient was used for predicting the flows from TOC to COD to the waste water treatment plant. The COD load was modeled with similar uncertainty as in reference TOC sampling. The water balance of waste water treatment was validated by the reference concentration of COD. The difference of COD predictions against references was within the same deviation of TOC-predictions. The modeled yield losses and retention values of TOC in pulping and bleaching processes and the modeled fixing of colloidal TOC to solids between the pulping plant and the aeration basin in the waste water treatment plant were similar to references presented in literature. The valid water balances of the waste water treatment plant and the reduction model of lignin-like substances produced a valid prediction of COD discharges out of the mill. A 30% increase in the release of lignin-like substances in the form of production problems was observed in pulping and bleaching processes. The same increase was observed in COD discharges out of waste water treatment. In the prediction of annual COD discharge, it was noticed that the reduction of lignin has a wide deviation from year to year and from one mill to another. This made it difficult to compare the parameters of COD discharges validated in plant dynamic simulation with another mill producing mechanical printing papers. However, a trend of moving from unbleached towards high-brightness TMP in COD discharges was valid.

Mechanical Design of Hydraulic Vise

The general task of clamping devise is to connect the parts to the machining centers so that the work piece could be fixed on its position during the whole machining process. Additionally, the work piece should be clamped easily and rapidly by the machine users. The purpose of this Master���s thesis project was to develop a product design and find out the dimensioning of a hydraulic vise system for Astex Engineering OY, which was taking care of the general principles of product design and development during the design process. Throughout the process, the needs of manufacturing and assembling were taken into consideration for the machinability and minimization of the cost of manufacturing. The most critical component of the clamping devise was modeled by FEM for the issue of strength requirements. This 3D model was created with Solidworks and FEM-analysis was done with Cosmos software. As the result of this design work, a prototype of the hydraulic vise was manufactured for Astex Engineering OY and the practical test.

Competitive flexibility in systems supplier companies in mechanical engineering industry

Systems suppliers are focal actors in mechanical engineering supply chains, in between general contractors and component suppliers. This research concentrates on the systems suppliers��� competitive flexibility, as a competitive advantage that the systems supplier gains from independence from the competitive forces of the market. The aim is to study the roles that power, dependence relations, social capital, and interorganizational learning have on the competitive flexibility. Research on this particular theme is scarce thus far. The research method applied here is the inductive multiple case study. Interviews from four case companies were used as main source of the qualitative data. The literature review presents previous literature on subcontracting, supply chain flexibility, supply chain relationships, social capital and interorganizational learning. The result of this study are seven propositions and consequently a model on the effects that the dominance of sales of few customers, power of competitors, significance of the manufactured system in the end product, professionalism in procurement and the significance of brand products in the business have on the competitive flexibility. These relationships are moderated by either social capital or interorganizational learning. The main results obtained from this study revolve around social capital and interorganizational learning, which have beneficial effects on systems suppliers��� competitive flexibility, by moderating the effects of other constructs of the model. Further research on this topic should include quantitative research to provide the extent to which the results can be reliably generalized. Also each construct of the model gives possible focus for more thorough research.

A Practical Micro Mechanical Model Based Local Approach Methodology for the Analysis of Ductile Fracture of Welded T-Joints

This thesis concentrates on developing a practical local approach methodology based on micro mechanical models for the analysis of ductile fracture of welded joints. Two major problems involved in the local approach, namely the dilational constitutive relation reflecting the softening behaviour of material, and the failure criterion associated with the constitutive equation, have been studied in detail. Firstly, considerable efforts were made on the numerical integration and computer implementation for the non trivial dilational Gurson Tvergaard model. Considering the weaknesses of the widely used Euler forward integration algorithms, a family of generalized mid point algorithms is proposed for the Gurson Tvergaard model. Correspondingly, based on the decomposition of stresses into hydrostatic and deviatoric parts, an explicit seven parameter expression for the consistent tangent moduli of the algorithms is presented. This explicit formula avoids any matrix inversion during numerical iteration and thus greatly facilitates the computer implementation of the algorithms and increase the efficiency of the code. The accuracy of the proposed algorithms and other conventional algorithms has been assessed in a systematic manner in order to highlight the best algorithm for this study. The accurate and efficient performance of present finite element implementation of the proposed algorithms has been demonstrated by various numerical examples. It has been found that the true mid point algorithm (a = 0.5) is the most accurate one when the deviatoric strain increment is radial to the yield surface and it is very important to use the consistent tangent moduli in the Newton iteration procedure. Secondly, an assessment of the consistency of current local failure criteria for ductile fracture, the critical void growth criterion, the constant critical void volume fraction criterion and Thomason's plastic limit load failure criterion, has been made. Significant differences in the predictions of ductility by the three criteria were found. By assuming the void grows spherically and using the void volume fraction from the Gurson Tvergaard model to calculate the current void matrix geometry, Thomason's failure criterion has been modified and a new failure criterion for the Gurson Tvergaard model is presented. Comparison with Koplik and Needleman's finite element results shows that the new failure criterion is fairly accurate indeed. A novel feature of the new failure criterion is that a mechanism for void coalescence is incorporated into the constitutive model. Hence the material failure is a natural result of the development of macroscopic plastic flow and the microscopic internal necking mechanism. By the new failure criterion, the critical void volume fraction is not a material constant and the initial void volume fraction and/or void nucleation parameters essentially control the material failure. This feature is very desirable and makes the numerical calibration of void nucleation parameters(s) possible and physically sound. Thirdly, a local approach methodology based on the above two major contributions has been built up in ABAQUS via the user material subroutine UMAT and applied to welded T joints. By using the void nucleation parameters calibrated from simple smooth and notched specimens, it was found that the fracture behaviour of the welded T joints can be well predicted using present methodology. This application has shown how the damage parameters of both base material and heat affected zone (HAZ) material can be obtained in a step by step manner and how useful and capable the local approach methodology is in the analysis of fracture behaviour and crack development as well as structural integrity assessment of practical problems where non homogeneous materials are involved. Finally, a procedure for the possible engineering application of the present methodology is suggested and discussed.

Water circulations for effective bleaching of high-brightness mechanical pulps

The amount of water available is usually restricted, which leads to a situation where a complete understanding of the process, including water circulations and the influence of water components, is essential. The main aim of this thesis was to clarify the possibilities for the efficient use of residual peroxide by means of water circulation rearrangements. Rearranging water circulations and the reduction of water usage may cause new problems, such as metal induced peroxide decomposition that needs to be addressed. This thesis introduces theoretical methods of water circulations to combine two variables; effective utilization of residual peroxide and avoiding manganese in the alkaline peroxide bleaching stage. Results are mainly based on laboratory and mill site experiments concerning the utilization of residual peroxide. A simulation model (BALAS) was used to evaluate the manganese contents and residual peroxide doses. It was shown that with optimum recirculation of residual peroxide the brightness can be improved or chemical costs can be decreased. From the scientific perspective, it was also very important to discover that recycled peroxide was more effective pre-bleaching agent compared to fresh peroxide. This can be due to the organic acids i.e. per acetic acid in wash press filtrate that have been formed in alkaline bleaching stage. Even short retention time was adequate and the activation of residual peroxide using sodium hydroxide was not necessary. There are several possibilities for using residual peroxide in practice regarding bleaching. A typical modern mechanical pulping process line consist of defibering, screening, a disc filter, a bleach press, high consistency (HC) peroxide bleaching and a wash press. Furthermore there usually is not a particular medium consistency (MC) pre-bleaching stage that includes additional thickening equipment. The most advisable way to utilize residual peroxide in this kind of process is to recycle the wash press filtrate to the dilution of disc filter pulp (low MC pre-bleaching stage). An arrangement such as this would be beneficial in terms of the reduced convection of manganese to the alkaline bleaching stage. Manganese originates from wood material and will be removed to the water phase already in the early stages of the process. Recycling residual peroxide prior to the disc filter is not recommended because of low consistencies. Regarding water circulations, the novel point of view is that, it would be beneficial to divide water circulations into two sections and the critical location for the division is the disc filter. Both of these two sections have their own priority. Section one before the disc filter: manganese removal. Section two after the disc filter: brightening of pulp. This division can be carried out if the disc filter pulp is diluted only by wash press filtrate before the MC storage tower. The situation is even better if there is an additional press after the disc filter, which will improve the consistency of the pulp. This has a significant effect on the peroxide concentration in the MC pre-bleaching stage. In terms of manganese content, it is essential to avoid the use of disc filter filtrate in the bleach press and wash press showers. An additional cut-off press would also be beneficial for manganese removal. As a combination of higher initial brightness and lower manganese content, the typical brightness increase varies between approximately 0.5 and 1% ISO units after the alkaline peroxide bleaching stage. This improvement does not seem to be remarkable, but as it is generally known, the final brightness unit is the most expensive and difficult to achieve. The estimation of cost savings is not unambiguous. For example in GW/TMP mill case 0.6% ISO units higher final brightness gave 10% savings in the costs of bleaching chemicals. With an hypothetical 200 000 ton annual production, this means that the mill could save in the costs of bleaching chemicals more than 400 000 euros per year. In general, it can be said that there were no differences between the behavior of different types of processes (GW, PGW, TMP and BCTMP). The enhancement of recycling gave a similar response in all cases. However, we have to remember that the utilization of residual peroxide in older mills depends a great deal on the process equipment, the amount of water available and existing pipeline connections. In summary, it can be said that processes are individual and the same solutions cannot be applied to all cases.

Mechanical closing of the paperboard package and the effect of the shape of paperboard package to its manufacturability

The main objective of this thesis was to design a hinge and a closing mechanism for the plastic rim of a paperboard package. Of the hinge and closing mechanisms the 3D-models were designed using SolidWorks program and the functionality of the mechanisms was tested with rapid prototype models. When a mechanism that worked was found, the manufacturability of the mechanisms was tested in an injection molding machine with changeable inserts. Another objective of this thesis was to test the effect of the shape of paperboard package to its manufacturability. The effect of the packages shape was tested with plastic tools made for three different shaped trays. Suggestions for further research were made according to the results of the thesis.

Azimuth thrusterin rungon lujuustekninen tarkastelu

Ty��ss�� perehdyttiin azimuth potkurilaitteen rakenteelliseen kest��vyyteen vaikuttaviin seikkoihin. Ty��n tavoitteena oli tutkia eri rakenneratkaisuja ja yksityiskohtia sek�� niiden vaikutusta koko potkurilaitteen toimintaan. Potkurilaitteiden lujuustekninen tarkastelu sis��lsi rakenteen eheyden tarkistuksen mekaanisten kuormitusten alla kuin my��s v��r��htelyk��ytt��ytymisen tutkimisen. Tarkastelun p����s����nt��inen kohde oli potkurilaitteen alarunko, eli laivan ulkopuolelle j����v�� osa. Diplomity�� oli osa kahden uuden potkurilaitteen kehitysprojektia. Projektissa esiin tulleita rakennemuutoksia vertailtiin vanhoihin, jo toteutettuihin rakenneyksityiskohtiin. Lis��ksi tutkittiin olemassa olevien rakenneratkaisujen hy��dynt��mist�� uusissa laitteissa. Huomiota kiinnitettiin my��s hitsien muotoiluun ja n��iden mitoitusk��yt��nt��ihin. Rungon ehyytt�� koskevat laskelman ovat hyvin pitk��lti suoritettu elementtimenetelm���� apuna k��ytt��en. Elementtimenetelm���� varten luotiin useita malleja kattaen kokonaisia potkurilaittee runkoja kuin my��s sen yksitt��isi�� osia. Elementtimenetelm��n avulla saatuja tuloksia vertailtiin k��ytett��viss�� oleviin mittaustuloksiin. Ty��ss�� havaittiin potkurilaitteen rungon mitoittavaksi tekij��ksi staattisessa tilanteessa muodostuvan voimansiirtolinja ja siin�� sijaitsevien hammaspy��rien siirtym��t. T��m��n seurauksena rungon taipumat ovat m����r����v��mpi�� geometrian kannalta kuin materiaalien sallitut j��nnitykset.

Kokeellisen moodianalyysin hy��dynt��minen s����riluun lujuuden m����ritt��misess��

Diplomity�� tehtiin Lappeenrannan teknillisen yliopiston konetekniikan laitokselle. Diplomity�� on osa teknillisen yliopiston biomekaanista tutkimusta, jonka tarkoituksena on mallintaa ihmisen tuki- ja liikuntaelimist��n toimintaa. Ty��ss�� pyrittiin selvitt��m����n, voitaisiinko s����riluuhun kohdistetun mekaanisen her��tteen aiheuttamaa v��r��htelyvastetta analysoimalla saada tietoa luun ominaistaajuuksista ja lujuudesta. Tietoa voitaisiin k��ytt���� esimerkiksi ostoporoosiriskin arvioinnissa sek�� ihmiskehon osien toimintaa kuvaavien simulointimallien verifioinnissa. Mittauslaitteistona k��ytettiin Br��el & Kj��r-moodianalyysilaitteistoa. Laitteistokokonaisuuteen kuuluivat her��tevasara, elektromagneettinen t��ristin, voima-anturi, kaksi kiihtyvyysmitta-anturia sek�� PulseLab 2.0 ���ohjelmistolla varustettu PC-laitteisto. Tulosten jatkoanalyysi suoritettiin MathWorks yhti��n MatLab v 4.0 -ohjelmistolla. Ty��ss�� esitellyn mittaustavan ja -laitteiston todettiin soveltuvan s����riluun v��r��htelyvasteen mittaamiseen. Mittaustulokset eri mittauskertojen v��lill�� samalla henkil��ll�� ovat yhtenev��t. Tutkimuksen tulosten perusteella ei voida osoittaa luun v��r��htelyvasteen ja lujuuden v��list�� suoraa korrelaatiota.

Kokeellisen moodianalyysin j��lkik��sittely ominaismuotojen visuaaliseksi tarkastelemiseksi

Kokeellinen moodianalyysi on kokeellinen menetelm��, jolla voidaan selvitt���� rakenteille ominaista v��r��htely��. Ty��ss�� oli kolme tavoitetta, jotka pyrittiin saavuttamaan. Ensimm��inen tavoite oli ohjeistuksen luominen rakenteiden ominaismuotojen visuaaliseksi tarkastelemiseksi Lappeenrannan teknillisell�� yliopistolla k��ytett��viss�� olevilla laitteistoilla ja ohjelmilla. Ohjeistuksen perustana on ajatus siit��, ett�� kokeellinen moodianalyysi saataisiin tehokkaampaan k��ytt����n koneensuunnittelun opetuksessa. Ohjeistus tehtiin p����asiassa kuvien ja kuvia tukevien selitysten avulla. Ty��n toisena tavoitteena oli verrata rakenteen ominaisv��r��htely��, kun se oli tuettu vapaasti ja kun se oli tuettu kiinte��sti sen luonnolliseen ymp��rist����n. Taajuuksia verrattaessa huomattiin, ett�� eri tavoin tuetut rakenteet k��ytt��ytyv��t eri tavalla, mik�� on otettava huomioon, kun tutkitaan kriittisi�� v��r��htelyj��. Ominaisv��r��htelyj�� voidaan selvitt���� my��s matemaattisesti esimerkiksi ����rellisten elementtien menetelm��ll��. Ty��n kolmantena tavoitteena oli verrata elementtimenetelm��ll�� ja kokeellisesti saatuja ominaisv��r��htelyn arvoja. Elementtimallia pyrittiin tarkentamaan eri parametrej�� muuttamalla niin, ett�� ominaistaajuuksien arvot vastaavat mahdollisimman hyvin toisiaan. Tavoite saavutettiin.