Investigation on the bar clamping position of a new type of precision cropping system with variable frequency vibration

Zhang, Lin Jie; Zhao, Shengdun; Lei, Jingting; Liu, W.

doi:10.1016/j.ijmachtools.2006.09.003

Cited by 26 publications

(11 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…According to the relation between law of crack propagation and loading, crack propagates along with linear decreasing of striking frequency and linear increasing of radial displacement. 11 Research results 25,26 of the author’s team have shown that during cropping, in order to finish blanking in shortest time and get the best quality cross section, not only should the average stress ratio on metal bar be increased continually, but also the frequency of the applied load on the metal bar should be continually decreased. 27,28 In short, two adjustable parameters, which are hammer striking displacement and hammer striking frequency, are combined with each other.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Experimental investigation on new low cycle fatigue precision cropping process

Zhao

Zhong

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part C:

View full text Add to dashboard Cite

The traditional cropping processes have some disadvantages, such as poor surface quality, low yield, the waste of materials, and high energy consumption. The low cycle fatigue precision cropping process with circumferential loading, which is a new type of precision cropping process, is studied. According to the stress concentration effect of the V-shape notch, the fatigue crack on the tip of the V-shape notch is prompted to initiate and extend. The working principle of the precision cropping machine is described. The criterion that whether the crack on the root of the V-shape notch is initiated or not is provided under the effect of low cycle fatigue loading. The materials which are 0.2%C steel, H59 copper, 0.45%C steel, 20Cr steel, and LY12 aluminum are tested under two control curves. The initiation and propagation of crack are accelerated and the good cross sections of the metal bar are obtained. The results show that the mean stress of the metal bar in the cropping process can be effectively reduced due to the stress concentration effect of the V-shape notch. The metal bar’s stable crack propagation and fracture can be obtained when constantly increasing striking displacement and reducing the striking frequency in the cropping process at the same time in the process.

show abstract

Section: Methodsmentioning

confidence: 99%

“…A new kind of process, which is variable frequency vibration cropping, is put forward in Zhang et al. 11 and Wang et al. 12 The process makes V-shaped notch root of metal bar to produce cracks until fracture.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on new low cycle fatigue precision cropping process

Zhao

Zhong

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part C:

View full text Add to dashboard Cite

show abstract

“…Therefore, in the course of the low-stress cropping, some necessary measures should be taken to reduce the influence on the cross-section quality. For example, the reasonable clamping position of the metal bar should be determined [9], and the structure of the eccentric block is changed into the adjustable eccentric block [10,11] and the external force load mode is studied in detail.…”

Section: The Vibration Performance Of the Cropping Machinementioning

confidence: 99%

Analysis of Modeling and Vibration Performance of a New Type of Cropping Machine

Zhang¹,

Zhao²

2014

TOMEJ

View full text Add to dashboard Cite

Abstract:In order to reduce the cropping force and enhance the cropping cross-section quality, a new type of cropping machine is proposed in this paper. The basic structure and working principle of the cropping machine are introduced. Based on D'Alembert's principle, the vibration equations of the cropping machine along the Y direction, the X direction and around X, Y, Z axes are built in detail and the motion curves of the vibration body in all directions are also obtained. The amplitude frequency response characteristic curve of the vibration body in the Y direction is given and the resonance frequency of the vibration body in the Y direction is about 7.94 rad/s. The cropping experimental results show that the cropping force acted on the metal bar is low and the cross-section quality is very high.

show abstract

“…At the present time, the common cropping method in industry is to shear bar directly with the common die, and this process is plagued with a big shearing force, a bad cross-section, a short lifetime die, and noise. Therefore, a new type of low stress cropping method was proposed and gradually used in industrial practice [1][2][3]. In the low stress cropping, the annular V-shaped notch on the surface circumference of metal bar is processed in advance and it skillfully utilizes the crack technology and the fatigue loading to make the crack checking and propagating along the prefabricated V-shape notch section for shearing the bar.…”

Section: Introductionmentioning

confidence: 99%

“…The crack initiation mainly includes three important aspects, namely, the initiation location, the initiation direction, and the initiation time. It is pointed out that the crack initiation time is far more than the summation of the crack extension time and the transient fracture time [4]. Moreover, the crack initiation time is difficult to compute.…”

Section: Introductionmentioning

confidence: 99%

Investigation on the Crack Initiation of V-Shaped Notch Tip in Precision Cropping

Zhang

Zhao

Wang

2014

Advances in Materials Science and Engineering

View full text Add to dashboard Cite

The crack initiation of V-shaped notch tip has a very important influence on the cross-section quality and the cropping time for every segment of metal bar in course of low stress precision cropping. By the finite element method, the influence of machining precision of V-shaped notch bottom corner on the crack initiation location is analyzed and it is pointed out that the crack initiation point locates in the place at the maximal equivalent stress change rate on V-shaped notch surface. The judgment criterion of the crack initiation direction is presented and the corresponding crack initiation angle can be calculated by means of the displacement extrapolation method. The factual crack initiation angle of the metal bar has been measured by using the microscopic measurement system. The formula of the crack initiation life of V-shaped notch tip is built, which mainly includes the stress concentration factor of V-shaped notch, the tensile properties of metal material, and the cyclic loading conditions. The experimental results show that the obtained theoretical analyses about the crack initiation location, the crack initiation direction, and the crack initiation time in this paper are correct. It is also shown that the crack initiation time accounts for about 80% of the cropping time for every segment of the metal bar.

show abstract

Investigation on the bar clamping position of a new type of precision cropping system with variable frequency vibration

Cited by 26 publications

References 4 publications

Experimental investigation on new low cycle fatigue precision cropping process

Experimental investigation on new low cycle fatigue precision cropping process

Analysis of Modeling and Vibration Performance of a New Type of Cropping Machine

Investigation on the Crack Initiation of V-Shaped Notch Tip in Precision Cropping

Contact Info

Product

Resources

About