Wyniki wyszukiwania - BazTech

1

Numerical and experimental study on the inner diameter uniformity of hollow shafts in cross-wedge rolling with mandrel

Zhou Jing, Shen Jinxia, Wang Baoyu, Huang Xu, Guo Wei

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

321--336

EN

The precision forming of inner hole is one of technological bottlenecks in Cross-wedge Rolling (CWR) of hollow shaft with mandrel. The inner diameters show signs of characteristic fluctuation despite under the control of mandrel. The uniformity of inner diameter was investigated by finite element simulation and experiments in this study. The inner hole expands at the knifing stage and shrinks at the sizing stage. The dimensional fluctuation of inner diameter is mainly resulting from the improper metal flow. The radial and axial metal flows are insufficient at the knifing stage, which resulting in the hole expansion at knifing zone. The hole shrinkage is caused by the relatively adequate radial metal flow at sizing stage. The experiment results show that the hole expansion increases with the increasing stretching angle and mandrel diameter and decreases with the increasing forming angle and initial wall thickness. The hole expansion first increases and then decreases with the increasing reduction ratio. The hole shrinkage has positive correlations with forming angle, reduction ratio and initial wall thickness, and negatively correlates with stretching angle and relative mandrel diameter. A modified CWR roll with the curved-surface knife is proposed to get rid of the hole expansion. Based on experiments and simulations, the most suitable geometric parameters of the curved-surface knife are determined. Using mandrel diameter compensation can reduce the phenomenon of hole shrinkage. These methods were applied to the trial rolling of a half-shaft sleeve part, and the results show that the methods significantly restrain the inner diameter fluctuation.

2

Numerical and experimental research on cross wedge rolling hollow shafts with a variable inner diameter

Shen Jinxia, Wang Baoyu, Zhou Xu, Li Junling

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 4

1497--1510

EN

The precise forming of inner hole has been a major technical difficulty in the cross wedge rolling (CWR) of hollow shaft. This paper proposes a new process to form hollow shafts with variable inner diameters by using the CWR with mandrel control. The forming characteristics and dimension precision of this process are analyzed by combining finite element modelling (FEM) and forming trials. The hole step of hollow shaft with variable inner diameter is formed in a spiral pattern. The helixes result in many micro-steps in hole step when forming the right-angle inner step. The metal flow lines demonstrated that mandrel step hindered the axial metal flow of inner hole and the metals were accumulated in hole step. The rolling load increases in the process of forming hole step. The mandrel is subjected to axial load when hole contacts the mandrel step. The roundness can be improved by reducing the mandrel diameter in knifing position. The axial accuracy of inner diameter can be classed as three parts: hole expansion, stable rolling, hole shrinkage. The compensated mandrel was designed to improve axial precision of inner diameter. The results showed that the inner hole dimension can be effectively controlled.

3

Numerical Analysis of a Skew Rolling Process for Producing a Stepped Hollow Shaft Made of Titanium Alloy Ti6Al4V

Pater Z., Bulzak T., Tomczak J.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

677--682

EN

The paper describes a rolling process for a hollow Ti6Al4V alloy shaft used in driving systems of light trucks. The shaft is formed by skew rolling using three tapered rolls. The principle of this forming process was discussed stressing its universality due to the potential of applying it for forming various products by one set of rolls. The numerical analysis results (product shape progression in rolling, wall thickness distribution, effective strain, temperature and variations in loads and torques) confirm that the proposed technique can be used for producing hollow long shafts.

4

Kształtowanie przez rozpychanie kołnierzy wałów drążonych

Pater Z., Gontarz A., Tomczak J.

Rudy i Metale Nieżelazne

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2012

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R. 57, nr 2

84-87

PL

W artykule zaprezentowano wyniki obliczeń numerycznych rozpychania kołnierza (w kształcie rozety) wałka drążonego. Szczegółowo przedstawiono analizę odkształceń, temperatury, sił kształtowania, progresję kształtu wyrobu, jak również parametry geometryczne narzędzi kształtujących. Obliczenia numeryczne przeprowadzono metodą elementów skończonych (MES).

EN

The paper presents results of a numerical analysis of jostling of hollow shaft flange (in rosette form). Strain, temperature, force distribution, shape progression of workpiece, and also geometric parameters of shaping tools are presented in this paper in details. Numerical calculations have been made with finite element method (FEM).

5

Symulacje numeryczne procesu obciskania obrotowego wielostopniowego wałka drążonego

Tomczak J., Pater Z.

Przegląd Mechaniczny

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2012

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nr 2

37-41

PL

W artykule przedstawiono wyniki analizy numerycznej nowatorskiego procesu obciskania obrotowego wielostopniowego wałka drążonego. Symulacje numeryczne procesu wykonano metodą elementów skończonych w warunkach przestrzennego stanu odkształcenia z uwzględnieniem zjawisk termicznych. Podczas obliczeń określono parametry geometryczne otrzymanych wyrobów, wyznaczono rozkłady naprężeń, odkształceń, temperatur oraz momentów kształtowania. Omówiono modele geometryczne zastosowane w symulacjach MES. W wyniku badań stwierdzono możliwość kształtowania osiowosymetrycznych odkuwek drążonych metodą obciskania narzędziami obrotowymi.

EN

Results of numerical analysis of a novel multistage process of rotational compression of hollow shaft were presented. Numerical simulations of the process were carried out with the use of finite element method in terms of spatial state of strain, taking into account thermal phenomena. During the calculations, geomet-ric parameters of derived products were evaluated, as well as distributions of stress, strain, temperature and forming moments. Geometric models used in the FEM simulations were discussed. The research revealed the possibility of forming axially-symmetrical forgings hollowed out by the method of rotational compression.

6

Force fit of a hollow shaft in a hub of large radius

Koleif I. A., Kamel M. H.

Mechanics and Mechanical Engineering

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1999

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Vol. 3, nr 2

175--180

EN

In this paper the problem of force fit of a hollow shaft in a hub of large radius is completed under the assumption of plane polar elasticity. Different materials are admitted and radial displacement of the inner and outer radius of the shaft together with that of the hub are allowed. Complete solutions are obtained and are compared with that of the solid shaft. In the case of solid shaft, the results showed that the strain energy is equally shared between the shaft and the hub.