Abstract
Due to the instable conditions caused by the wear of rollers, macro voids inevitably occur in skew rolling steel balls. Macro voids in rolled balls greatly weakens the mechanical properties, resulting in the scrapping of about 23% of all skew rolling balls. This paper adopts the floating-pressure method (FPM) to eliminate macro voids in rolled steel balls, and mainly focuses on the investigation of the influencing factor void closure in skew-rolled balls. The research contents are listed as follows: Firstly, the mechanical model of FPM eliminating void in rolled steel balls is established, and the theoretical relationship between influencing factors of void closure is obtained. Then, the metal flow behaviors, the stress distribution and the effect of process parameters on void closure are revealed by numerical analysis. Subsequently, based on the uniform design method, the prediction equation of the required temperature and air pressure for compacting various inferior rolled balls with different diameter by FPM is deduced. Finally, the FPM experiment is carried out to verify the results of numerical analysis. The research results provide theoretical guidance for eliminating macro voids in skew-rolled steel balls.
Highlights
The skew rolling process is widely applied in the near net forming of bearing steel balls due to its several advantages such as high working efficiency, high material utilization rate, low cost and low forming force, and the fine machining of skew rolling must be arranged to guarantee the final dimension of bearing steel balls
With regard to those inferior balls with macro voids, macro voids inside rolled steel balls cannot be eliminated by fine machining, and it would be faced with scrap disposal, resulting in a great waste of material
This paper aims to investigate the influencing factors offactors void closure rolled ball and of macro voids
Summary
The skew rolling process is widely applied in the near net forming of bearing steel balls due to its several advantages such as high working efficiency, high material utilization rate, low cost and low forming force, and the fine machining of skew rolling must be arranged to guarantee the final dimension of bearing steel balls. Focus on the defects during the process of skew rolling steel balls, but the radical problem of macro voids induced analysis and control of defects during the process of skew rolling steel balls, but the radical problem by roller wear beby avoided. Rolled steel balls with macro voids need to be subjected to the temperature and air pressure. This paper aims to investigate the influencing of voidinside closure inside rolled establish the prediction model of the required temperature and air pressure. 4, the the Finite Element (FE) model of eliminating void inside rolled steel balls by FPM is established.
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