Thermomechanical Analysis of a Helical-Wedge Rolling Process for Producing Balls

Pater, Z.; Tomczak, J.; Bartnicki, J.; Bulzak, Tomasz

doi:10.3390/met8110862

Cited by 14 publications

(9 citation statements)

References 8 publications

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“…Upon establishing the critical damage values for the nine f i functions the authors conducted the numerical simulation of the CWR process of the harrow tooth preform. The simulation was performer in Simufact.Forming v.15, a software that has been used by the authors to model cross and skew rolling processes [33,34,35,36,37]. The obtained results remained in compliance with the results of the verifying experimental examination.…”

Section: Numerical Modeling Of the Process Of Cross Wedge Rolling supporting

confidence: 54%

Prediction of Crack Formation for Cross Wedge Rolling of Harrow Tooth Preform

et al. 2019

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The article presents the issue of material fracture during the process of cross-wedge rolling (CWR). The object of the research was the process of forming a harrow tooth preform. In the conducted analysis nine damage criteria were applied. The critical value of damage was determined with a new calibrating test, basing on rotational compression of a sample in a channel. The results of calculations were compared to the results of experimental testing performed in laboratory conditions in Lublin University of Technology. On the basis of the obtained results an assessment of the applied damage criteria and their applicability in the analysis of CWR processes was conducted.

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Section: Numerical Modeling Of the Process Of Cross Wedge Rolling supporting

confidence: 54%

Prediction of Crack Formation for Cross Wedge Rolling of Harrow Tooth Preform

et al. 2019

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“…As a result, they were able to model the process of cutting end scrap material with end-face cavities. The same approach was adopted in the cross rolling of balls [39] and helical rolling of balls [40]. This time the critical damage value was equal to 3.…”

Section: Introductionmentioning

confidence: 99%

Rotary compression in tool cavity—a new ductile fracture calibration test

Pater

Tomczak

Bulzak

et al. 2020

Int J Adv Manuf Technol

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Ductile fracture is one of the most common failure modes in hot metal forming. It can be predicted by means of so-called damage functions that describe the relation between stress, deformation and fracture initiation. A practical use of these functions requires the knowledge of the critical damage value of the material that is determined by calibration tests based on compression, tension and torsion. For the prediction to be correct, one must ensure that the modelled and real stresses are in agreement. Previous studies did not offer any effective test for determining critical values of damage under changing load conditions that occur in cross and skew rolling processes, among others. To compensate for this knowledge gap, researchers at the Lublin University of Technology have developed a new test consisting in rotary compression of a test-piece in a cavity between the tools, which is described in this paper. In the proposed test, a cylindrical test-piece is rolled over a cavity (impression) created by grooves on two mating tools. The cavity height is smaller than the test-piece diameter. At the critical value of the forming length, the state of stress induced thereby in the test-piece axis causes fracture. Knowing the critical forming length, it is possible to determine the critical value of damage by numerical modelling. The practical application of the proposed test is illustrated through the case of C45 grade steel subjected to forming in the temperature range 950-1150°C. The analysis makes use of the normalized Cockcroft-Latham (NCL) criterion of ductile fracture.

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“…The state of stress in the axial area of the sample, occurring in this test, causes the material to crack as a result of the so-called Mannesmann effect. A similar state of stress occurs in numerous industrial processes, such as cross-wedge rolling, helical rolling and punching according to the Mannesmann method [41][42][43][44]. For this reason, the limit values of the damage function obtained using the new test have a significant utilitarian meaning.…”

Section: Abbreviationmentioning

confidence: 99%

Rotational Compression of Cylindrical Specimen As a New Calibrating Test for Damage Criteria

et al. 2020

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The subject-matter of the article is the ductile fracture of materials—A phenomenon occurring in numerous metal forming processes. In order to prognosticate the possibility of a fracture, damage criteria are employed. Their effectiveness, however, depends on the accurate determination of the critical values of damage. These values are obtained through calibrating tests, where the stress state has to be as similar to the actual process as possible. The currently employed calibrating tests do not enable one to determine the limit values of the damage function when the Mannesmann effect occurs. Therefore it was not possible to effectively prognosticate the material fracture in the processes of cross- and skew-rolling. A new calibrating test, based on rotational compression of a cylindrical sample, in which the fractures are caused by the Mannesmann effect, was developed at the Lublin University of Technology. This test was discussed in the article, with a particular focus on the stress and strain state in the sample. A practical use of the test was presented on the example of C45 grade steel, formed in the temperature equal 1150 °C. In the research ten material damage criteria were adopted.

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Thermomechanical Analysis of a Helical-Wedge Rolling Process for Producing Balls

Cited by 14 publications

References 8 publications

Prediction of Crack Formation for Cross Wedge Rolling of Harrow Tooth Preform

Prediction of Crack Formation for Cross Wedge Rolling of Harrow Tooth Preform

Rotary compression in tool cavity—a new ductile fracture calibration test

Rotational Compression of Cylindrical Specimen As a New Calibrating Test for Damage Criteria

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