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Author:Uusimäki, Jari Rauno
Title:Valssausvoimavaihtelun pienentäminen nauhavalssaimessa
Minimizing the rolling force variations in a hot strip mill
Publication type:Master's thesis
Publication year:2004
Pages:77      Language:   fin
Department/School:Konetekniikan osasto
Main subject:Koneensuunnitteluoppi   (Kon-41)
Supervisor:Kuosmanen, Petri
Instructor:Jokisaari, Juha
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
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Location:P1 Ark Aalto  6128   | Archive
Abstract (eng): A common structure in hot strip mill backup roll bearings is to attach the conical sleeve of the slide bearing to the mill's shaft by a key.
The key groove, cut to the conical sleeve, locally decreases the strength of the structure, causing deflections when load is exerted to it.
These deflections are observed as rolling force variations, falling into sync with the backup roll rotation.

In this research, we developed a new method to minimize force variations, based on 3D grinding of the mill rolls.
We prepared four finite element models describing the backup roll bearings, and used those to determine the shape and magnitude of the deflection, which occurs during the roll's revolution.
Using these models, we constructed the compensation curve for the 3D grinding.
A cam shape, 30 µm in height, was grinded on the rolls, in order to compensate the deflection.

The empirical research took place at the hot strip mill of the Rautaruukki Raahe factory.
The 3D grinding was applied to the backup rolls at mill stand number six.
The rolling force was measured using both conventional and 3D grinded mill rolls.
The analysis was done by using synchronous time averaging, which separates the upper and lower portions of the rolling force variation.

The rolling force variation diminished into negligible at the upper backup roll, and reduced significantly at the lower backup roll.
Furthermore, our 3D grinding method is easily commissioned method.
Abstract (fin): Kuumanauhavalssaimen tukivalssien laakereissa käytetään yleisesti rakennetta, jossa liukulaakerin kartioholkki on kiinnitetty valssin akselil1e kiilalla.
Kartioholkkiin jyrsitty kiilaura heikentää rakennetta paikallisesti, mistä syntyy joustoja kiilauran tullessa kuormituskohtaan.
Joustot havaitaan tukivalssien pyörimiseen tahdistuvana valssausvoimavaihteluna.

Tässä tutkimuksessa kehitettiin nauhavalssaimen voimavaihtelun pienentämiseksi uusi valssien 3D-hiontaan perustuva menetelmä.
Valssituolien tukivalssien laakereista laadittiin neljä FEM-mallia, joiden avulla selvitettiin tukivalssien laakerien kerran kierroksella tapahtuvan jouston muoto ja suuruus.
FEM-mallien tuloksien perusteella laadittiin 3D-hionnan ohjauskäyrä.
Valsseihin hiottiin 30 µm korkea nokkamainen muoto, jolla pyrittiin kompensoimaan tukivalssien kerran kierroksella tapahtuva jousto.

Käytännön kokeet tehtiin Rautaruukin Raahen tehtaan kuumanauhavalssaimella. 3Dhiontaa sovellettiin nauhavalssaimen kuutostuolin tukivalsseihin.
Valssausvoima mitattiin perinteisesti hiotuilla valsseilla ja verrattiin tuloksia 3D-hiottujen valssien tuloksiin.
Valssausvoiman analysoinnissa käytettiin synkronoitu aikakeskiarvostus-menetelmää, minkä ansiosta voimavaihtelusta pystyttiin erottelemaan ylä- ja alatukivalssien osuudet.

Lopputuloksena 3D-hiotuilla valsseilla ylätukivalssiin tahdistetun voimavaihtelun havaittiin poistuneen lähes kokonaan ja alatukivalssiin tahdistettu voimavaihtelu oli pienentynyt selvästi perinteisesti hiottuihin valsseihin verrattuna.
Työn aikana todettiin lisäksi 3D-hionnan olevan helposti käyttöönotettava menetelmä.
ED:2004-11-11
INSSI record number: 26486
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