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Modeling of Cold Pilgering of Tubes
Dalarna University, School of Technology and Business Studies, Materials Technology. Luleå University of Technology.
2017 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Cold pilgering is a challenging tube forming process in terms of modeling due to the complexity in kinematic of tools, friction condition and material behavior. The process development has mostly been based on simple formulas and costly full-scale tryouts. The aim in this study is to develop validated Finite element models of cold pilgering to increase the understanding of influence of the process parameters on the produced tubes.

In the course of this thesis, three-dimensional mechanical and thermo-mechanical Finite element models of cold pilgering were developed. The commercial code MSC.Marc was used in the simulations. General 3D models are needed to be able to capture asymmetric deformation in cold pilgering. It was found that tool deflections together with elastic deformation of roll dies have considerable influence on the rolling force. Furthermore, the strain rate and temperature effects on the response of the material and thereby on the rolling force were evaluated.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology , 2017.
Series
Licentiate thesis, ISSN 1402-1757
Keyword [en]
Cold pilgering, finite element method, tube forming, tool elasticity, roll flattening
National Category
Applied Mechanics
Research subject
Steel Forming and Surface Engineering
Identifiers
URN: urn:nbn:se:du-25902ISBN: 978-91-7583-873-1 (electronic)ISBN: 978-91-7583-872-4 (print)OAI: oai:DiVA.org:du-25902DiVA: diva2:1136747
Presentation
2017-05-31, E130, Luleå tekniska universitet, Luleå, 10:25 (English)
Opponent
Supervisors
Available from: 2017-08-29 Created: 2017-08-29 Last updated: 2017-08-29Bibliographically approved
List of papers
1. Finite element modelling of cold pilgering of tubes
Open this publication in new window or tab >>Finite element modelling of cold pilgering of tubes
2015 (English)In: Proceedings of the 8th International Conference on Computational Plasticity - Fundamentals and Applications, COMPLAS 2015, 2015, 716-726 p.Conference paper, Published paper (Refereed)
Abstract [en]

Cold pilgering is a cold forming process used during manufacturing of seamless tubes. The tube with a mandrel inside is fed forward and rotated in stepwise increments, while the roll stand moves back and forth. The total plastic deformation of the tube is such that the cross-sectional area of the tube decreases and the length of the tube increases during the process. However, this is performed in many small incremental steps, where the direction of deformation in a material point changes at each stroke. Most published models of cold pilgering use simplified material models. In reality, the flow stress is dependent on temperature, strain rate, strain history and microstructure. In this work, temperature and strain rate distributions are computed, using a 3D thermo-mechanical FE model, and the influence of temperature and strain rate on the rolling force is investigated. The Johnson-Cook model is employed to describe the flow stress using isotropic hardening. The results show that strain rate and temperature have a significant influence on the roll separation force.

Keyword
Cold forming, Cold pilgering, Finite element analysis, Johnson-cook, Seamless tubes, Thermo-mechanical analysis, Von mises plasticity, Finite element method, Plastic flow, Plasticity, Tubes (components), Tubing, Pilgering, Von-Mises plasticity, Strain rate
National Category
Materials Engineering
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-21303 (URN)000380573600069 ()2-s2.0-84992261190 (Scopus ID)9788494424465 (ISBN)
Conference
13th International Conference on Computational Plasticity, COMPLAS 2015, 1 September 2015 through 3 September 2015
Available from: 2016-03-31 Created: 2016-03-31 Last updated: 2017-08-29Bibliographically approved
2. Finite element modeling of tube deformation during cold pilgering
Open this publication in new window or tab >>Finite element modeling of tube deformation during cold pilgering
2016 (English)In: MATEC Web of Conferences, 2016, Vol. 80, 15004Conference paper, Published paper (Refereed)
Abstract [en]

A three-dimensional finite element model of cold pilgering of stainless steel tubes is developed in this paper. The objective is to use the model to increase the understanding of forces and deformations in the process. The focus is on the influence of vertical displacements of the roll stand and axial displacements of the mandrel and tube. Therefore, the rigid tools and the tube are supported with elastic springs. Additionally, the influences of friction coefficients in the tube/mandrel and tube/roll interfaces are examined. A sensitivity study is performed to investigate the influences of these parameters on the strain path and the roll separation force. The results show the importance of accounting for the displacements of the tube and rigid tools on the roll separation force and the accumulative plastic strain.

Series
MATEC Web of Conferences, E-ISSN 2261-236X
Keyword
cold forming
National Category
Materials Engineering
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-23429 (URN)10.1051/matecconf/20168015004 (DOI)000392331100086 ()
Conference
NUMIFORM 2016: The 12th International Conference on Numerical Methods in Industrial Forming Processes
Available from: 2016-11-21 Created: 2016-11-21 Last updated: 2017-08-29Bibliographically approved
3. Finite Element Analysis of cold pilgering using elastic roll dies
Open this publication in new window or tab >>Finite Element Analysis of cold pilgering using elastic roll dies
2017 (English)Conference paper, Published paper (Refereed)
Abstract [en]

A finite element model of cold pilgering with elastic roll dies have been developed and used to investigate the influence of roll die deformation on the material flow, contact region, roll separating force and tube dimensions. Full scale experiments were performed to validate the contact surface and tube dimensions. The results show that the influence of roll die flattening is not significant on the contact length. However, elastic deformation of roll die has strong influence on both the wall thickness reduction and roll separating force. Thus it is recommended to consider elasticity of roll dies when forces and tube dimensions are estimated.

Place, publisher, year, edition, pages
Elsevier, 2017
Series
Procedia Engineering, ISSN 1877-7058 ; 2017
Keyword
cold pilgering; cold forming; tube forming; roll flattening; contact length; roll separating force; finite element method; tool elasticity; tube dimension
National Category
Applied Mechanics
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-25901 (URN)
Conference
International Conference on the Technology of Plasticity, ICTP 2017, Cambridge, United Kingdom, 17-22 September 2017
Available from: 2017-08-29 Created: 2017-08-29 Last updated: 2017-08-29Bibliographically approved

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