A Numerical Method For Simultaneous Prediction of Metal Flow and Temperatures in Upset Forging of Rings

Nagpal, V.; Lahoti, G. D.; Altan, Taylan

doi:10.1115/1.3439455

Cited by 51 publications

(53 citation statements)

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“…After the early work by Kunogi [21] and Kudo [13], Male and Cockcroft [22] improved the test method and presented it in usable form. Many works have been done using this method to investigate the friction behavior in bulk metal forming processes, both analytically [13,21], experimentally [23], and numerically [16,24,25]. This method essentially measures the dimensional changes of a specimen to arrive at the magnitude of friction coefficient or factor.…”

Section: Introductionmentioning

confidence: 99%

FE analysis of the sensitivity of friction calibration curves to dimensional changes in a ring compression test

2011

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This paper is concerned with an analysis of the sensitivity of friction calibration curves to the frictional shear factor in a ring compression test. The main objective of this study is to examine the sensitivity of the FEA calibration curves of a ring compression test to the frictional shear factor. Different calibration curves were investigated by measuring dimensional changes at different positions of a ring specimen, including changes in the internal diameter at the middle and top section of the specimen, the outer diameter at the middle and top section, and the degree of surface expansion at the top surface. The initial ring geometries employed in the analysis maintain a fixed ratio of 6:3:2, i.e., the outer diameter : inner diameter : thickness ratio of the ring specimen, which is generally known as a 'standard' specimen, in order only to determine the sensitivity of the calibration curves for the measurement of dimensional changes at different positions to the frictional shear factor. A perfectly plastic material was modeled for the simulations using rigid-plastic finite element code. Analyses were performed within a definite range of friction as well as over the entire range of friction to uncover the different sensitivities of calibration curves to interfacial friction given different ranges of friction. The results of this investigation are summarized in terms of a dimensionless gradient. It was determined from the results that the friction calibration curves according to measurements of the dimensional changes at different positions of a ring specimen show different degrees of linearity and sensitivity to the frictional condition on the contact surface. Among these differences, the friction calibration curve upon changes in the degree of surface expansion at the contact boundary was found to be relatively linear and sensitive to the frictional condition over the entire range of friction.

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Section: Introductionmentioning

confidence: 99%

FE analysis of the sensitivity of friction calibration curves to dimensional changes in a ring compression test

2011

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“…Although such a problem has been widely investigated on the basis of upperbound theorem [18][19][20][21][22][23][24], the method we employed, also based on the upper-bound theorem, is significantly distinguishable. Specifically, an arbitrary function, which governs the velocity field in deforming material at each step of the upsetting process, is associated with the upper-bound theorem to formulate the total forming energy rate equation.…”

Section: Introductionmentioning

confidence: 99%

A variational upper-bound method for analysis of upset forging of rings

Yeh

2005

Journal of Materials Processing Technology

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“…[8] Several methods have been developed for quantitative evaluation of interface friction such as clamp rolling, ring-compression, etc., in which the ringcompression test is a widely accepted way to measure the interface friction between the work pieces and dies. [9,10] By using the ring compression test, Li et al studied the lubricities of glass and graphite in deformation process of Ti-6Al-4V titanium alloy under high temperatures and strain rates, and presented that increasing the strain rate leads the friction to reduce. [11,12] Zhu et al determined the shear friction coefficient of the titanium alloy Ti-6Al-4V in the hot forging process by means of the ring compression test during a physical experiment and FE simulation.…”

Section: Introductionmentioning

confidence: 99%

Friction and Heat Transfer Coefficient Determination of Titanium Alloys during Hot Forging Conditions

et al. 2016

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In this paper, the contact condition between Ti-6Al-4V specimens and heated tool steel is studied with the purpose of calculating the heat transfer coefficient (HTC) and coefficient of friction (COF) at the interface of the specimens and the tools. Three types of surfaces that are, Ti-6Al-4V specimens with no coating, 40 and 80 mm of glass coating have been analyzed in this study. The paper first presents the experimental results of HTC tests and ring compression tests and then, two Finite Element (FE) numerical models are developed and applied for calculation of the HTC and COF value under three aforementioned surface conditions. The final results are the identification of both coefficients and the identification of the most promising surface condition, when forging Ti-6Al-4V specimens at temperatures about 940 C.

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A Numerical Method For Simultaneous Prediction of Metal Flow and Temperatures in Upset Forging of Rings

Cited by 51 publications

References 0 publications

FE analysis of the sensitivity of friction calibration curves to dimensional changes in a ring compression test

FE analysis of the sensitivity of friction calibration curves to dimensional changes in a ring compression test

A variational upper-bound method for analysis of upset forging of rings

Friction and Heat Transfer Coefficient Determination of Titanium Alloys during Hot Forging Conditions

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