Preliminary Analysis of a Rotary Compression Test

Pater, Z.; Walczuk, Patrycja; Lis, Konrad; Wójcik, Łukasz

doi:10.12913/22998624/86812

Cited by 20 publications

(14 citation statements)

References 11 publications

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“…Along with being deformed the testpiece is rotated by action of the friction forces, which causes it to roll in the tool cavity over a forming length s. The role of the cavity side walls is to prevent axial flow (elongation) of the material. During the forming process, the radial stresses in the test-piece axis oscillate from compressive (the minimum values occur vertically) to tensile (the maximum values are observed in a horizontal direction, reflecting the sliding motion of the upper tool) [42]. The stresses change twice per one revolution of the test-piece.…”

Section: Principle Of the Rotary Compression Testmentioning

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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Section: Principle Of the Rotary Compression Testmentioning

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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“…Therefore, it is necessary to devise a new test that would enable determination of the critical damage function for periodically varying stresses, as is the case in cross and skew rolling. It seems that rotary compression can be such test, as preliminarily described in [10]. Nevertheless, given a lack of results obtained from the rotary compression test, arbitrarily increased limit values obtained in tensile tests are used to this end [11].…”

Section: Numerical Simulation Of a Helical-wedge Rolling Process For mentioning

confidence: 99%

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

Pater

Tomczak

Bartnicki

et al. 2018

Metals

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The paper presents a complete numerical model of a helical-wedge rolling process for producing balls. The model was designed in Finite Element Method (FEM)-based Forge NxT v.1.1 that enables the simulation of both forming and separating balls. A comparison of numerical results with experimental findings revealed a very high agreement in both qualitative and quantitative terms. The developed numerical model was used to investigate the effect of flange shape on the helical-wedge rolling process for producing balls with a diameter of 125 mm. Three types of flange tools were investigated, and the best results were obtained for a wedge-shaped flange.

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“…Furthermore, tests on determining the damage criterion in the process of rotational compression in a channel of a disc-shaped sample [1,26] were conducted. An analysis of the results has shown a similarity of the behaviour of commercial plasticine and 50HS grade steel formed in the temperature range 950 • C-1150 • C. (Figure 2) presents the comparison of the curves of material flow of plasticine formed in the temperature range 0°C to 15°C and 50HS steel formed at the temperature 1150 ˚C.…”

Section: Methodsmentioning

confidence: 99%

Physical Modeling of Cross Wedge Rolling Limitations

et al. 2020

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This article presents the results of model tests aiming to verify the possibility of applying commercial plasticine as a model material for modelling the limits to the cross-wedge rolling process. This study presents a comparison of the results of laboratory testing and physical modelling of cross-wedge rolling (CWR) processes. Commercial plasticine was the model material used in the research to model 50HS grade steel formed in 1150 °C. The model material was cooled to 0 °C, 5 °C, 10 °C, 12,5 °C, and 15 °C. Physical modelling of neckings and slippages is only possible when the plasticine is heated to 12.5 °C prior to forming. Commercial plasticine does not enable one to model the cracking process inside the rolled element.

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Preliminary Analysis of a Rotary Compression Test

Cited by 20 publications

References 11 publications

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

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

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

Physical Modeling of Cross Wedge Rolling Limitations

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