Procjena vremena izrade proizvoda regresijskim modelima

Antolić, Dražen (2007) Procjena vremena izrade proizvoda regresijskim modelima. = Scientific master's thesis , Sveučilište u Zagrebu, Fakultet strojarstva i brodogradnje, UNSPECIFIED. Mentor: Ćosić, Predrag.

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Abstract (Croatian)

Rad se bavi projektiranjem tehnoloških procesa za pojedinačnu i maloserijsku proizvodnju. Problem je definiranje parametara osnovnog tehnološkog procesa, potrebnih tehnoloških postupaka, redoslijeda tehnoloških operacija i potrebnog vremena izrade. Postoje različiti pristupi projektiranju tehnoloških procesa, a svima je zajednička neizbježnost potrebe za tehnologom u procesu projektiranja tehnoloških procesa, koja se zasniva prvenstveno na osobnom stručnom znanju tehnologa. Dakle, tehnolog rješava probleme projektiranja tehnoloških procesa koristeći uglavnom prijašnja vlastita ili tuđa iskustva, intuiciju, a u mnogo manjoj mjeri i zajedničko ekspertno znanje, strukturirano u baze znanja. U praksi to rezultira velikim utroškom ljudskog rada u projektiranju tehnoloških procesa, a sve češće i za proizvode koji se u tvornici neće niti proizvoditi, jer je ugovor dobila konkurentska tvrtka na tržištu. Troškovi koji time nastaju za tvrtku, ali i činjenica da se parametri tehnoloških procesa značajno razlikuju od tehnologa do tehnologa, što ukazuje na upitnost kvalitete projektiranih tehnoloških procesa, potaknuli su autora ovog rada na sagledavanje, definiranje, te rješavanje ovog problema. Pri definiranju problema provedena je detaljna analiza poznatih rješenja, a izvršeno je i prethodno istraživanje u cilju utvrđivanja mogućih čimbenika koji utječu na tehnološke parametre, pri čemu su utvrđeni i oni koji do sada nisu uzimani u obzir. Na temelju tako definiranog problema, izvršeno je obimno istraživanje na uzorku različitih pozicija, pri čemu su svi podaci pohranjivani u relacijsku bazu podataka razvijenu od strane autora. Ova baza podataka ujedno je i baza znanja, budući su i prije samog istraživanja u nju ugrađena poznata znanja vezana uz projektiranje tehnoloških procesa, kao primjerice, međusobni odnos razreda hrapavosti i reda tolerancije, predmnijevani redoslijed operacija i sl.) Podaci su temeljito obrađeni, a za procjenu vremena izrade oblikovani su različiti regresijski modeli, uglavnom temeljeni na razgranatoj strukturi podataka iz uzorka. Osmišljeno je i novo i originalno rješenje problema pod nazivom osnovni tehnološki proces (OTP). OTP je model odlučivanja u projektiranju tehnoloških procesa kojeg je moguće u potpunosti automatizirati, budući se temelji na brzim, jednostavnim i relativno pouzdanim obrascima odlučivanja. OTP povezuje postojeća tehnološka znanja u zajedničkoj bazi podataka, upotpunjenoj sa potpuno novim elementima i metodama za klasifikaciju dijelova i procjenu vremena izrade. Prvenstveno su to tip OTP-a, grana OTP-a, regresijski modeli i jednadžbe za procjenu vremena izrade na temelju regresijskih modela. Predloženo rješenje moguće je relativno brzo primijeniti u praksi, a daljnja nadgradnja i razvoj rješenja išao bi u pravcu istraživanja zajedničkog regresijskog modela s većim stupnjem generalizacije.

Abstract

This paper deals with process planning for individual production, as well as for production of small series. The problem lies in defining parameters of primary processes planning, required technological procedures, sequence operations and required machining time. There are different approaches in process planning, but they all have something in common: the imminence of a need for a technologist in process planning, which is based primarily on personal expertise of the technologist. The technologist solves problems of process planning mainly using prior, personal or somebody else's, experiences, intuition and, to a smaller extent, shared expertise, structured into a knowledge base. In practice, it results with a lot of human labor in process planning, and very frequently even for products, which will not be produced in the factory, because a competitive company on the market got the deal. What made the author of this paper to observe, define and resolve this problem are the costs that arise in this way, but also the fact that parameters of technological processes significantly differ from a technologist to a technologist, which points out the questionability of process planning quality. By defining the problem, a detailed analysis of known solutions was conducted, as well as a prior research, with a goal to define possible factors influencing technological parameters, and it defined even those, which were not taken into account until now. Based on such definition of the problem, a voluminous research was conducted, on the sample of different positions, while all data was saved in a relational data base developed by the author of this paper. This data base is at the same time a knowledge base, because prior knowledge related to process planning was integrated into it even before this research, as for example, correlation between roughness class and tolerance class, predefined sequence operations and similar. Data was thoroughly processed and different regression models were formed for machining time estimate, mostly based on extended data structure from the sample. A new and original solution of the problem was defined under the name Basic Technological Process (BTP). BTP is a determining model in process planning, which can be fully automatized, since it is based on fast, simple and relatively reliable forms of determination. BTP merges existing technological knowledge in shared data base, completed with entirely new elements and methods for parts classification and machining time estimate. Those are primarily BTP type, BTP branch, regression models and equations for machining time estimate based on regression models. Proposed solution could be used in practice in a relatively short time, and further upgrade and solution development would be directed to research of shared regression model with a higher grade of generalization.

Item Type: Thesis (Scientific master's thesis)
Uncontrolled Keywords: osnovni tehnološki proces, projektiranje tehnoloških procesa, grupna tehnologija, redoslijed operacija, osnovne tehnološke operacije, osnovni uzorak, višestruka postupna linearna regresija, vrijeme izrade, baza znanja, metode optimiranja
Keywords (Croatian): basic technological process, process planning, group technology, sequence operations, basic technological operations, basic sample, stepwise multiple regression, machining time, knowledge base, optimization methods
Subjects: TECHNICAL SCIENCE > Mechanical Engineering
Date Deposited: 10 Dec 2015 08:58
Last Modified: 10 Dec 2015 08:58
URI: http://repozitorij.fsb.hr/id/eprint/4941

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