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RISS 인기검색어
- 검색키워드
- 저자 : Roman Kulagin (검색결과 2 건)
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Off-Axis Twist Extrusion for Uniform Processing of Round Bars
Yan Beygelzimer,Roman Kulagin,Marat I. Latypov,Viktor Varyukhin,김형섭 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.4
The present paper introduces a twist extrusion (TE) process capable of processing of round bars with uniform deformation and reports physical, analytical, and numerical modeling of the process. It is shown that the ability to treat round bars can be achieved by design of special off-axis TE dies in which the axis of the twist surface is displaced from the central axis of the bar being processed. Physical modeling conducted in the current study with plasticine demonstrates the feasibility of off-axis TE. A marker insert technique employed in the physical model reveals that tool-controlled flow (ideal helical flow) of the material is dominant in the process. Analytical model developed in the present study explains why using off-axis TE dies leads to uniform deformation and how this deformation uniformity depends on the die geometry. The main conclusions made upon analytical modeling are confirmed with complement finite element simulations. The simulations also show that the main deformation mode in off-axis TE is simple shear at the intersection planes between the twist and the straight channels of the die. The present paper introduces a twist extrusion (TE) process capable of processing of round bars with uniform deformation and reports physical, analytical, and numerical modeling of the process. It is shown that the ability to treat round bars can be achieved by design of special off-axis TE dies in which the axis of the twist surface is displaced from the central axis of the bar being processed. Physical modeling conducted in the current study with plasticine demonstrates the feasibility of off-axis TE. A marker insert technique employed in the physical model reveals that tool-controlled flow (ideal helical flow) of the material is dominant in the process. Analytical model developed in the present study explains why using off-axis TE dies leads to uniform deformation and how this deformation uniformity depends on the die geometry. The main conclusions made upon analytical modeling are confirmed with complement finite element simulations. The simulations also show that the main deformation mode in off-axis TE is simple shear at the intersection planes between the twist and the straight channels of the die. The simulations also show that the main deformation mode in off-axis TE is simple shear at the intersection planes between the twist and the straight channels of the die.
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Simple Shear Model of Twist Extrusion and Its Deviations
Marat I. Latypov,이명규,Yan Beygelzimer,Roman Kulagin,김형섭 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.3
Twist extrusion (TE) is a severe plastic deformation method with a potential for commercialization. Advancing TE toward industrial use requires in-depth understanding of deformation during the process and its dependence on processing factors. The helical flow model introduced with the concept of TE provides for a concise description of deformation in the process. To date, however, it was unclear under which conditions the helical flow model yields accurate predictions of deformation in TE. This paper presents a systematic finite-element study performed to identify effects of some key process and material factors on deformation in TE and its departure from the ideal deformation described by the helical flow model. It was found that high strain-hardening rate and friction lead to violations of the assumptions of the helical flow model and that these violations result in departure from the ideal deformation. Deviations from the ideal deformation tend to increase on decreasing the length of the twist channel. Friction effects appear especially critical to be considered for accurate prediction of deformation in TE. Finite-element simulations taking friction into account show good qualitative agreement with earlier marker-insert experiments. The results of the present finite-element study allowed for defining the simple shear model of TE.
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