Numerical and experimental investigation on the influence of main motor rotational frequency in fine-cropping

Zhong, B.; Zhao, Shengdun; Zhao, Renfeng; Liao, Jiean

doi:10.1177/0954406213486592

Cited by 13 publications

(3 citation statements)

References 19 publications

(30 reference statements)

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“…Zhao et al 8 pointed out that the metal bar’s stable crack propagation and fracture are obtained when constantly increasing the striking displacement and reducing the striking frequency in the cropping process, simultaneously. Tang et al 9,10 , Zhong et al 11 and Zhang et al 1 found that a linear increment of the stroke-time curve and a linear decrement of the strike frequency-time curve improve the cropping efficiency and the quality of the fracture section. By changing the above factors, the sufficient efficiency of cropping and qualified quality of cross-section get together.…”

Section: Introductionmentioning

confidence: 99%

The investigation of low-cycle fatigue crack propagation of 16 Mn eccentric bar based on the acoustic emission technique

Ren

Dong

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part B:

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Compared to the traditional cropping technology, low-cycle fatigue cropping can reduce load and improve cross-section quality. Geometric factors of V-shaped notch and processing parameters (such as load amplitude and load frequency) influence the cropping efficiency and section quality. By changing the factors, the sufficient efficiency of cropping and quality of cross-section get together. However, the influences of material defects, geometric parameters, loading frequency and other factors are different in each stage of the whole cropping process. If the effects of the parameters on the each stage of cropping process are clear, the higher productivity and the better cross-section quality will be obtained by applying suitable parameter on each stage of cropping process. To investigate the effects of eccentric ratio on each stage of low –cycle fatigue cropping process, a suitable monitoring method is needed. This study proposes acoustic emission (AE) technique to detect the low-cycle fatigue cropping process of 16 Mn eccentric bar (The bar prefabricated eccentric notches. The prefabricated notch improve the efficiency of cropping). The parameters of signals such as counts and kurtosis during the low–cycle fatigue process are obtained. According to the counts changes over time, the process of the 16 Mn metal bar cropping can be divided into three stages: the crack initiation stage, the crack propagation stage, and the fracture stage. Based on the cumulative counts, the eccentric ratio’s influence on the time of each cropping process stage is obtained. The time of the crack initiation stage and the final fracture stage doesn’t increase with the eccentric ratio. The time of the propagation stage influenced by the eccentric ratio greatly. Besides, the eccentric ratio’s influence on the cross-section quality is studied by using an advanced optical microscope system. The cross-section quality was influenced by the eccentric ratio significantly. The results of the paper indicate the acoustic emission (AE) monitoring technique is a useful method to detect the process of low-cycle fatigue cropping. Especially, it provide effective information to investigate the effects of the notch eccentric ratio during the low-cycle fatigue cropping process. The eccentric ratio’s effects on each stage of low-cycle fatigue cropping process offer guidance to improve low-stress fatigue cropping efficiency and cross-section quality.

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Section: Introductionmentioning

confidence: 99%

The investigation of low-cycle fatigue crack propagation of 16 Mn eccentric bar based on the acoustic emission technique

Ren

Dong

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…However, there are still collapse zones left at the contact area of bars, together with serious problems as wear and breakage of the blade. Low stress blanking method, based on the crack technology, firstly cut annular grooves on the surface of the bars to generate stress concentration, and then apply circumferential cyclic load to accelerate the initiation and extension of fatigue crack [3,4], which can obtain billets with high quality section. Whereas, the blanking efficiency is relatively low(6~8 billets per minute); on the other hand, the stress grooves with V shape profiles [5] are mainly processed by lathe or milling, which don't generate severe stress concentration, and grooving of hard materials is still difficult.…”

Section: Introductionmentioning

confidence: 99%

Investigation on the High-speed Precision Shearing of 5140 Steel Bars Pre-grooved by Laser

et al. 2017

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Abstract.A new blanking method is proposed to improve the quality of metal bars, by introducing the laser pre-grooving and high-speed precision shearing technology. The working principle is introduced, and the calculation method of the laser groove depth is given. By means of finite element method, the elastic-plastic deforming, damage initiation and crack propagation behaviour of a 5140 steel bar under high-speed shearing are obtained; furthermore, the corresponded shear force-displacement property is analysed in detail. After that, high speed shearing experiments are done of laser grooved 5140 steel bars. The results show that the 5140 steel bar undergoes rapid elastic and little plastic deformation before crack, and micro cracks initially appears in the lateral area with the damage value of 0.53; then main vertical cracks form and extend along the shearing direction; the fracture section of the billet is flat and smooth, with a section inclination of 0.3°and a weight tolerance of 0.35%.

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“…Some new different lowstress bar fine-cropping methods have been proposed based on the stress concentration in the last two decades. 4,[12][13][14][15][16] Although some of the disadvantages have been improved in some extent, the cross-section quality and the efficiency are still required to be improved indeed. Besides, due to lack of the correct and appropriate cropping mechanism, the optimal cropping load control strategy of the existing low-stress fine-cropping methods still remains unclear.…”

Section: Introductionmentioning

confidence: 99%

New controllable and near net bar fine-cropping system

Zhong

Zhao

Bin³

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part B:

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In this article, a new controllable and near net low-stress bar fine-cropping system was proposed and developed by combined using the stress concentration effect of the prefabricated V-groove and the propagation crack. The bar finecropping experiments were successfully carried out using a new proposed cropping load control strategy. Although the level of the stress intensity factor range DK greatly influences the cropping time and the cross-section quality, the cropped-billets can be directly used for the precision forging industry without additional machining.

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Numerical and experimental investigation on the influence of main motor rotational frequency in fine-cropping

Cited by 13 publications

References 19 publications

The investigation of low-cycle fatigue crack propagation of 16 Mn eccentric bar based on the acoustic emission technique

The investigation of low-cycle fatigue crack propagation of 16 Mn eccentric bar based on the acoustic emission technique

Investigation on the High-speed Precision Shearing of 5140 Steel Bars Pre-grooved by Laser

New controllable and near net bar fine-cropping system

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