du.sePublications
Change search
Refine search result
1 - 7 of 7
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Tahir, Mohammed
    Dalarna University, School of Technology and Business Studies, Material Science.
    LOWWEAR varmvalsning WP12012In: Strategiskt stålforskningsprogram för Sverige 2007–2012: En sammanfattning av forskningsprogrammet och de ingående projekten, presenterade vid Jernkontorets programkonferens, 4–5 september 2012, Stockholm: Jernkontoret , 2012, p. 18-18Conference paper (Other (popular science, discussion, etc.))
    Abstract [sv]

    En konstruktion av slitage och temperaturprofiler in-line¬mätare designades och ett modifierat valslitage beräkningsmodell presenteras där inflytandet från arbetsvalsmaterial och det valsade materialets egen-skaper utvärderades. HSS, HiCr och IC arbetsvalsar utvärderades. Olika par i färdigverk med olika valsar-rangemang, skillnader i slitage mellan övre och undre valsar och påverkan av smörjning undersöktes.  Genom att anpassa modellen till olika valsningsförhållanden; varmvalsverk, plåtverk och steckelverk, erhölls möjligheten att undersöka modellen i drift.

    En studie av valsmaterial (Vancron 40, Sverker 3 and Vanadis 23) med avseende på valsslitage, ytkvalitet och påkladdning genomfördes. Valsmaterialen utvärderades experimentellt i laboratorium och i pilotvals-verk. Fyra olika industriella smörjmedel utvärderades. Vancron 40 gav lovande materialkvalitet tack vare sina goda egenskaper gällande ytfinhet i kombination med motstånd mot påkladdning och motstånd mot adhesiv nötning.

  • 2.
    Tahir, Mohammed
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Absalyamova, V.
    The use of solar energy in steel industries2011Conference paper (Refereed)
    Abstract [en]

    The purpose of this study is to make a design and simulation of the solar photovoltaic system which would attempt to cover the energy demand of the initial part of the pickling line hydraulic system at the SSAB steel plant. Proposed photovoltaic pumping systems in this work are to run the system into the hydraulic pump directly, developing of PV systems which produce energy in DC form. The second proposed photovoltaic technology is a type of PV system which delivers power to an AC load. © 2011 IEEE.

  • 3.
    Tahir, Mohammed
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Holmberg, Jesper
    Dalarna University, School of Technology and Business Studies, Material Science.
    The impact of tapered work rolls in the finishing mill during hot rolling2012In: Iron & Steel Technology Conference Proceedings, Warrendale, PA: Association for Iron & Steel Technology , 2012, p. 1601-1609Conference paper (Refereed)
    Abstract [en]

    Few studies were done to assess the knowledge of the impact of tapered work rolls in the finishing mill during hot rolling. Hansson, L.et al. studied the use of advanced process models for plate and strip rolling in the Scandinavian Steel Industry [1]. Their work thatincludes simulations of work roll shift with tapered and CVC rolls have results a basis for new investments for profile and flatnesscontrol equipment in steel rolling mills. Rosenthal D. et al. studied a method of influencing the strip contour in the edge region of arolled strip [2]. Special CVC rolls were used as work rolls for influencing the strip contour in the edge areas and to study.Concerning this project, early analysis of work roll data suggested that the tapering of the work rolls was subordinated to the CVCprofileand that a greater than allowed tapering would not affect the result of the rolling process. A grinded profile which is out oftolerance on the other hand, would result in a change in CVC-profile.The purpose of this project was to study the impact of the tapering on the work rolls during hot rolling in the finishing mill. Customgrinded work rolls of CVC-type have been placed in finishing mill, stand 6 (F6) and the axial loads during the following rolling hasbeen studied and evaluated. The deviation of the centre of a strip, flatness of a strip as well as the equivalent camber of the work rollshave also been analyzed for further evaluations of the impact on the rolling results.Theoretically calculation model of the profile of the CVC work rolls and axial force directed toward roll edges was described. Customgrinded work rolls of CVC-type have been placed in mill stand number 6 and the axial loads during the following rolling has beenstudied and evaluated.The impact of tapered work rolls towards CVC profile, axial force, the deviation of the centre of a strip and flatness was presented.The work project finally resulted in new guidelines in grinding of the work rolls in the finishing mill.The work is done in the finishing mill of the strip rolling mill, Figure 1. The strip rolling mill comprising six-high rolling stands wherework rolls and backup rolls at stand 2 to 6 are containing CVC work rolls.Data of the specific strip rolling mill, the type and the characteristics of the used work rolls and strip properties were described [3].Due to different rolling conditions; high temperature in the early stands (thermal cracks) and low temperature and high incident rate inthe last stands (mechanical damage), HSS and HCr rolls were used in stands F1-F3 and IC rolls in stands F4-F6. The studied work rollwas of IC type.

  • 4.
    Tahir, Mohammed
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Jonsson, N.G.
    Lagergren, J
    Wikström, L.
    Hedenlund, H
    Evaluation of tool material Vancron 40 with regard to wear, surface quality and galling2012In: Proceedings of  JSI 2012 - 30th International Steel Industry Conference, December 18-19, Paris, France, Paris: B&W , 2012, , p. 2Conference paper (Refereed)
    Abstract [en]

    Resistance to adhesive wear on tool material can be improved by increasing the tool hardness, high ductility and decreasing of friction coefficient between the tool and the work material. In a similar way, resistance to galling can be increased by increasing the tool hardness and decreasing of friction. The purpose of this project was to investigate the use of Vancron 40 as work rolls in cold rolling of stainless steel in cluster rolling mills. Considerable factors were among others, the influence of different industrial lubricants, minimizing of temperature rising during rolling, lowering of rolling forces, longer life of rolls, easier grinding of rolls, increase the oil film bearing at normal cold rolling conditions and improving surface roughness of the final products.

    For using of work rolls in cold rolling cluster mills, roll material Vancron 40 was evaluated with regard to roll wear, surface quality and galling. Currently used roll type ASP23 was used as reference roll in the evaluation. The experiments were performed, as much as possible, in accordance to steel industries recommendations. The experiments were conducted with a 4-high pilot rolling mill at Swerea MEFOS in Luleå which is equipped for rolling of both flat and long products. The experiment was done for different industrial mineral-based lubricants. Lubrication was applied in a controlled form to the upper and lower work rolls and in the contact zone. To achieve the proposed final thickness, five passes were rolled. The characteristic of the upper and the lower work rolls, during rolling, was also examined. The pilot experimental results gave promising result in surface roughness, galling and roll material hardness. Due to its chemical and physical properties, Vancron 40 is believed to be the best solution to resist adhesive wear and galling in cold rolling process that require higher accuracy. 

  • 5.
    Tahir, Mohammed
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Jonsson, Nils-Göran
    Lagergren, Jonas
    Ceron, Ermanno
    Technical University of Denmark.
    Off-line testing of alternative of industrial lubricants and different tool materials for cold rolling of stainless steel2013Conference paper (Other academic)
    Abstract [en]

    The present study tests different roll materials and lubricants for cold rolling, using a strip reduction test equipment at The Technical University of Denmark. Aims was to study the roll/tool material wear resistance and the resistance towards galling, i.e. lubricant film breakdown causing pick-up of work piece material on the roll surface and subsequent scoring of work piece surfaces. The four industrial lubricants investigated all consisted of mineral oil with fatty acid additives. The work piece material was stainless steel, AISI 304. The materials tested were NARVA 12B from Åkers, using the cold work tool steel SVERKER 3 from Uddeholm (AISI D2), SUPRA 3 from Åkers using the PM tool steel VANADIS 23 from Uddeholm and Åkers special finely distributed carbides and nitrides tested roll material, using an anti-seizure PM tool steel VANCRON 40. Evaluation of resistance to wear was done; during 20 % strip reduction NARVA 12B/SVERKER 3 showed a low surface roughness when lubricant “A” was used and during both 10 % and 20 % strip reduction VANCRON 40 showed a low surface roughness when lubricant “C” was used. Together with the lubrication the surface topography of the roll material is expected to influence friction. Evaluation of resistance to galling was done. Results showed VANCRON 40 to be especially prone towards galling.

  • 6.
    Tahir, Mohammed
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Mattsson, Robert
    Modeling and analysis of the work-roll grinding depth and the roll wear of the work-roll in Steckel hot rolling mill2013Conference paper (Other academic)
    Abstract [en]

    Thermal expansion, elastic deformation and roll wear are some of the main factors influencing work-roll geometry in the hot rolling process and thereby rolling gap appearance and finally the flatness and profile of the hot rolled material. The purpose of this industrial project was to compile the parameters that influence strip crown of Steckel hot rolling mill, where the influence of these parameters has significant impact to optimize the roll adjustment to achieve a greater availability and higher yield. Focusing on roll wear influence, the evaluation of the grinding depth of work rolls toward roll wear was conducted. In addition to that, the roll wear prediction model in the strip width was developed and roll wear resistance of work-rolls used in a Steckel hot rolling mill has been evaluated. The rolled material used in this project was martensitic stainless chromium steel.

    Hardness measuring with Leeb-method shows that softening occurs in the contact area between strip and work roll, which is still present after a re-grinding process. The grinding depth was varied to investigate the influence on the measured softening. It was clear that an increased grinding depth reduced the softening and the work roll attained a hardness condition close to the one of an unused roll. Wear is a function of the hardness of the roll and thus the wear of the work roll due to different grinding depths was analyzed during actual rolling. The results showed that the wear coefficient remained the same even though the softening was reduced by increasing the grinding depth.

    A model to calculate the wear as a function of the position on the work roll width has been developed in this project. This was done to be able to model the local wear variations during a campaign. This was achieved by simulating the varying force along the contact between strip and work roll and between work roll and back-up roll. The software program used in the evaluation is CROWN426.

     By using Design of Experiments and the software MODDE, a polynomial fit was assigned to the rolling force between the work rolls and the strip (F1) and the force between work rolls and backup rolls (F2) by MLR and PLS, respectively, for faster calculation and the ability to use the model as an on-line tool. Finally, the polynomials, F1 and F2, were used to calculate the wear as a function of the force and number of rotations of the work-roll in contact with the strip. The results show that the model can predict the total varying wear with less than 7 % maximum average error for the rolled steel grade, martensitic stainless chromium steel.

  • 7.
    Tahir, Mohammed
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Sjögren, Björn
    Swerea MEFOS AB.
    LOWWEAR hot rolling WP12012Report (Other academic)
    Abstract [en]

    LOWWEAR hot WP 1 consists of three main parts. The first part includes design of in-line wear and temperature profile gauge for strip and plate mills.

    The second part is the study of roll wear prediction model for hot strip and plate mills.

    The third part includes the evaluation of roll materials (Vancron 40, Sverker 3 (RT60) and Vanadis 23 (ASP23)) with regard to roll wear, surface quality and galling. Roll materials were evaluated experimentally in laboratory and in pilot rolling mill.

     

    The purpose of the first part was to develop a gauge that could be inserted in the mill to measure wear and temperature profiles of both work rolls. This gauge should, be easier and faster to use, than existing gauges and be able to show the shape of the top and bottom roll separately.

    The gauge was designed as an adjustable measuring device so that it could measure the work rolls independent of the distance between them, within a range of 50 – 110 mm. The reason for this design feature is that different mills have different possibilities of opening the work rolls and it can also vary from time to time, depending on back-up and work roll diameters at the moment. The goal was set to 45 mm and the initial design had 45 mm but due to different changes in the design it had to be increased to 50 mm. These design changes delayed the making of the gauge and all original design features were not implemented during the project time. This delay was also the reason why this part was stopped by the project committee before it was finished.

     

    The purpose of the second part is to develop a roll wear prediction model to improve the process control systems of rolling mills by developing accurate roll wear prediction models that takes more influential parameters into consideration, among others. This was done on the basis of measured roll-wear. By means of this model roll wear of three roll grades, HSS, HiCr and IC were evaluated.

     

    A modified prediction model was presented where the influence of work roll and strip grades were evaluated. The contribution of roll wear from contact area (work roll /strip) and between work roll and back-up rolls was investigated. Different finishing mill stands with different work roll arrangements, differences of roll wear of the upper and lower rolls, the influence of lubrication with mixed and similar strip grades were also studied. By adjusting the model to different rolling conditions, hot strip mill, plate mills and steckel mills, possibilities of testing the modified prediction model in operation, offline and online, were investigated. Using some industrial adjustments, the modified model was used for research and master thesis projects for industrial applications. This was done for hot strip mills, plate mills and steckel mills.

     

    The third part was a study of roll materials, using four different industrial lubricants, laboratory strip reduction tests and pilot experiments were conducted and analyzed. Currently used roll type ASP23 was used as reference roll in the evaluation. The severe tribological conditions of “strip reduction test” (scratch test) gave some evaluation measures about surface roughness and galling. Scratches due to galling identified easily and the sliding length determined. Vancron 40 shows promising through its “surface coating” which is integrated into the finished tooling material. It also shows high resistance to galling, toward adhesive wear under severe conditions for low and high reductions.

     

    The pilot experiment was conducted in a 4-high rolling mill at Swerea MEFOS. Final thickness, work roll temperature after rolling and surface roughness of the strip and work rolls was measured and evaluated. The tests were conducted with different industrial lubricants. To achieve the proposed final thickness, five passes were rolled with a constant reduction of 25 %. The character of upper and lower work roll during rolling was also examined. Lubrication was applied in controlled form to the upper and lower work rolls and into the roll gap. The pilot experiment confirms that Vancron 40 is a promising material for work rolls, through its good performance in surface roughness and combination of galling resistance and adhesive wear resistance.

1 - 7 of 7
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf