Vpliv notranjih napetosti na velikost in obliko izdelkov iz jeklene pločevine

Kovič, Jaka (author)

V okviru diplomskega dela smo obravnavali problem nekontrolirane spremembe dimenzij in oblike obdelovanca med obdelavo s CNC rezkarjem, ki pa niso nastale zaradi napačnih nastavitev ali pogreškov stroja, ampak zaradi obnašanja samega materiala. Obdelovanci zaradi tega niso ustrezali predpisanim dimenzijskim zahtevam, ker mora biti konstrukcijski element (ohišje linearnega električnega podajalnika) izdelan v zelo ozkih tolerančnih mejah. Kljub temu, da so se obdelovanci pred obdelavo z rezkarjem napetostno žarili je še vedno prihajalo do nekontroliranih deformacij. Vzrok za nekontrolirano spremembo oblike in dimenzij smo iskali v morebitnih zaostalih notranjih napetostih, ki bi morebiti ostale v obdelovancu po predhodnih obdelavah (valjanje, rezanje). Namen diplomske naloge je bil zato dobiti informacijo o napetostnem stanju, ki je bilo prisotno v ploščatem profilu pred in po napetostnem žarjenju ter kako napetostno žarjenje vpliva na trdoto in mikrostrukturne spremembe samega materiala. Napetostno stanje smo preiskovali z metodo vrtanja slepe izvrtine ter za primerjavo še z rentgensko uklonsko metodo. Ugotovili smo, da žarjenje za odpravo notranjih napetosti ni bilo najbolj uspešno, saj so bile zaostale notranje napetosti na nekaterih mestih še vedno relativno visoke.

• Language: Slovenian
• Keywords: meritve zaostalih notranjih napetosti, metoda vrtanja izvrtine, rentgenska uklonska metoda, preiskave jeklene pločevine
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2019
• PID: 20.500.12556/RUL-113274
• COBISS.SI-ID: 1850975
• Publication date in RUL: 18.12.2019

KOVIČ, Jaka, 2019, Vpliv notranjih napetosti na velikost in obliko izdelkov iz jeklene pločevine [online]. Bachelor’s thesis. [Accessed 24 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=113274

Secondary language

• Language: English
• Title: Influence of residual stresses on size and shape of products from steel sheet metal

Abstract

In the diploma thesis, we treated the problem of uncontrolled changes of dimensions and shape of the workpiece during CNC mill cutting, which were not caused by incorrect settings or machine errors, but by the behavior of the material itself. For this reason, the workpiece did not meet the prescribed dimensional requirements, since the structural element (linear electric actuator housing) must be constructed within very narrow tolerance limits. Although the workpieces had been annealed before machining, uncontrolled deformation was still occurring. The cause of the uncontrolled changes in shape and dimensions was ascribed to residual internal stresses that might remain in the workpiece after pre-machining steps (rolling, cutting). The purpose of the diploma thesis was to obtain information on the stress state present in the flat profile before and after stress relief annealing and how annealing affects the hardness and microstructural changes of the material. The residual stress state of the workpiece has been investigated by the hole drilling method and for comparison with the X-ray diffraction method. We found that stress relief annealing was not successful since the residual stresses were still relatively high and could cause the distortion of the workpiece during mill cutting.

• Keywords: residual stresses, measuring residual stresses, drilling hole method, XRD method, steel sheet analysis