doctoral thesis
Janez Turk (Avtor), Daniel Svenšek (Mentor)

Povzetek

Plastic injection molding is a manufacturing process for producing complexly shaped plastic components, widely used in mass production industries. The process involves injecting molten polymeric material into a mold cavity, where it solidifies and takes the desired shape. During cooling, the solidified plastic continuously deforms due to thermal shrinkage, which can lead to warping of the final product or the appearance of surface defects, such as sink marks. Precise prediction of these deformations is essential for optimizing the injection molding process and ensuring the quality of the final product. In this study, we present a novel thermoelastic simulation method that predicts local deformation in injection molded parts by continuously calculating the displacement and stress fields of the solidifying plastic throughout the production process. Our approach accounts for the intricacies of part shape and enables the prediction of surface defects without requiring any specific material property measurement or calibration of the method. The method relies on material characterization data typically used in standard injection molding simulation analyses. The plastic injection molding process can be divided into three phases: the filling phase, the packing phase, and the cooling phase. Each of these phases has its pressure behavior regime in the liquid core of the product, which represents, along with the temperature change, an elastomechanical load for the plastic product. The pressure behavior in each of the phases is explained in this work, with a novel addition being a simple model of pressure behavior in the packing phase and the calculation of equilibrium pressure in the molten core during the cooling phase, which is crucial for predicting part deformation and ultimately for assessing the potential for void formation. We verified the accuracy of the thermoelastic method by comparing the results with measurements of products we injected using different process parameters. We also tested the method's performance with the result of a profilometry measurement published in the literature.

Ključne besede

elastomechanics;plastic injection molding;residual stress;molding defects;sink marks;warpage;

Podatki

Jezik: Angleški jezik
Leto izida:
Tipologija: 2.08 - Doktorska disertacija
Organizacija: UL FMF - Fakulteta za matematiko in fiziko
Založnik: [J. Turk]
UDK: 621.767
COBISS: 181785091 Povezava se bo odprla v novem oknu
Št. ogledov: 22
Št. prenosov: 5
Ocena: 0 (0 glasov)
Metapodatki: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Ostali podatki

Sekundarni jezik: Slovenski jezik
Sekundarni naslov: Termoelastomehanika s faznim prehodom iz tekočine v trdnino
Sekundarni povzetek: Brizganje plastike je proizvodni postopek za izdelavo plastičnih komponent zapletenih oblik, močno razširjen v masovni industriji. Postopek vključuje vbrizgavanje staljene polimerne mase v votlino kalupa, kjer se strdi in dobi želeno obliko. Med hlajenjem se strjena plastika zaradi termalnih skrčkov neprekinjeno deformira, kar lahko privede do zvijanja končnega izdelka ali nastanka površinskih napak, kot je posedanje. Natančna napoved teh deformacij je bistvena za optimizacijo postopka brizganja in zagotavljanje kakovosti končnega izdelka. V tej študiji predstavljamo termoelastično simulacijsko metodo za računanje deformiranosti brizganih izdelkov z neprekinjenim izračunavanjem deformacijskega in napetostnega polja strjevane plastike skozi vse faze proizvodnega procesa. Tak pristop omogoča napovedovanje površinskih napak, ne da bi bilo treba določiti kakšne posebne materialne lastnosti ali opraviti kalibracijo. Metoda temelji na podatkih o lastnostih materiala, ki se običajno uporabljajo v standardnih analizah simulacije brizganja plastike. Proces brizganja plastike je mogoče razdeliti na tri faze: fazo polnjenja, naknadno fazo in fazo hlajenja. Vsaka faza ima svoj režim obnašanja tlaka v staljeni sredici izdelka, ki skupaj s temperaturno spremembo predstavlja elastomehansko breme za plastični izdelek. Obnašanje tlaka v vsaki od faz je v tem delu pojasnjeno, novost je enostaven model obnašanja tlaka v naknadni fazi ter izračunavanja ravnovesnega tlaka v staljeni sredici v fazi hlajenja, ki je ključen za napovedovanje deformacije kosa in ne nazadnje tudi za ocenjevanje možnosti za nastanek lunkerjev. Natančnost termoelastične metode smo preverili tako, da smo rezultate primerjali z meritvami izdelkov, ki smo jih nabrizgali z različnimi procesnimi parametri. Prav tako smo delovanje metode preverili z rezultatom profilometrske meritve, objavljene v literaturi.
Sekundarne ključne besede: elastomehanika;brizganje plastike;notranje napetosti;posedenost;
Vrsta dela (COBISS): Doktorsko delo/naloga
Študijski program: 0
Konec prepovedi (OpenAIRE): 1970-01-01
Komentar na gradivo: Univ. v Ljubljani, Fak. za matematiko in fiziko, Oddelek za fiziko
Strani: 95 str.
ID: 22503399