The influence of multi-point roller-dies on the shape deviation differences of profile in flexible stretch-bending forming

2021 ◽  
pp. 095440542110410
Author(s):  
Jicai Liang ◽  
Chengxiang Han ◽  
Yi Li ◽  
Ce Liang ◽  
Wenming Jin
Keyword(s):  
Contact Zone ◽  
Shape Deviation ◽  
Target Shape ◽  
Stretch Bending ◽  
Processing Accuracy ◽  
Distance Difference ◽  
The Difference ◽  
Large Shape

In the process of flexible 3D stretch bending, the shape deviation difference between the contact zone and non-contact zone is studied. It is obvious that in the contact zone, the die regulates the deformation of the profile to make it conform to the target shape with small shape deviation; in the non-contact zone, the profile has no die restriction and deviates from the target shape with large shape deviation. When the dies are placed equidistantly along the x-axis, the shape deviation of the non-contact zone near the clamp side is greater than that near the middle of the profile. Arrange the distance between adjacent dies in equal ratio along the x-axis, so that the spacing near the clamp side is a little smaller, and the spacing near the middle of the profile is a bit larger. The difference between the shape deviation of the non-contact zone profile near the clamp side and the middle of the profile decreases, and the maximum shape deviation is reduced, which greatly improves the processing accuracy and quality. However, with the increase of the distance difference between adjacent dies, the shape deviation difference of the non-contact zone near the middle of the profile also increases greatly. Although the clamp side decreases, the maximum shape deviation has become the shape deviation of the profile in the non-contact zone near the middle of the profile.

scholarly journals CONSTRUCTION OF A REGRESSION MODEL OF THERMAL RESISTANCE OF A CONTACT PSEUDO MEDIUM

2021 ◽  
Vol 23 (3) ◽  
pp. 47-54
Author(s):  
A.F. Denisenko ◽  
◽  
L.Yu. Girth ◽  
Keyword(s):  
Thermal Resistance ◽  
Regression Model ◽  
Metal Cutting ◽  
Operating Experience ◽  
Design Stage ◽  
Contact Thermal Resistance ◽  
Limit Values ◽  
Cutting Equipment ◽  
Processing Accuracy ◽  
The Difference

The operating experience of metal-cutting machines made it possible to develop reasonable recommendations for the permissible limit values of temperature for the main subsystems of the machine, which determine the accuracy of processing. However, the decrease in the seriality of the manufactured metal-cutting equipment and the constant improvement of its designs require the development of models that are the basis of engineering techniques that allow at the design stage to predict the thermal picture of the main machine units that affect the processing accuracy. In connection with a significant number of factors influencing the formation of contact thermal resistance, and the difference in the weight of their action, it is proposed to use a pseudolayer (pseudo-medium), consisting of areas of actual contact and cavities filled with air or oil, for their comprehensive consideration in the thermal model of joining parts. To determine the significant factors that dominate the contact thermal resistance, a number of one-factor experiments were carried out. To develop a regression model of temperature change in the contact zone, a PFE of type 24 was performed. The results obtained were verified by the Cochran, Student and Fisher criteria.

Comparison of Ellipsoidal and Equivalent Torispherical Heads Under Internal Pressure: Buckling, Plastic Collapse and Design Rules

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Jinyang Zheng ◽  
Yehong Yu ◽  
Yehong Chen ◽  
Keming Li ◽  
Zekun Zhang ◽  
...  
Keyword(s):  
Failure Modes ◽  
Good Prediction ◽  
Plastic Collapse ◽  
Design Equation ◽  
Fe Method ◽  
Shape Deviation ◽  
Design Rules ◽  
Collapse Pressure ◽  
Current Design ◽  
The Difference

Abstract Ellipsoidal and torispherical heads, whose geometric shapes are close, are usually used as end closures of internally pressurized vessels. In pressure vessel codes, for example, ASME BPVC Section VIII and EN13445-3, ellipsoidal heads are designed as torispherical heads using geometric equivalency approaches. However, the difference between ellipsoidal and equivalent torispherical heads has not been studied in detail. In this paper, we first investigate shape deviation between the two types of heads. Then we compare elastic–plastic behaviors between ellipsoidal and equivalent torispherical heads as well as their failure modes, i.e., buckling and plastic collapse (bursting). It is found that ellipsoidal heads have more buckling resistance than equivalent torispherical heads, indicating that the current design rules for buckling of ellipsoidal heads based on the geometric equivalency approaches result in uneconomical design. In addition, experimental and numerical results show that such heads experience geometric strengthening. The finite element (FE) method considering the effect of geometric strengthening provides a good prediction of plastic collapse pressure. However, the current design equation for bursting does not consider the effect of geometric strengthening, also leading to uneconomical design. Therefore, in order to avoid uneconomical design, we recommend that (1) with respect to buckling of ellipsoidal heads, a new design equation be proposed rather than implementing the geometric equivalency approaches, and (2) the current design equation for bursting be deleted, and a new design equation, considering the effect of geometric strengthening, be proposed for bursting of ellipsoidal and torispherical heads.

scholarly journals Research on Springback Control in Stretch Bending Based on Iterative Compensation Method

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Zhiyuan Zhang ◽  
Rui Ma ◽  
Chunge Wang ◽  
Jun Zhao
Keyword(s):  
Material Properties ◽  
Dimensional Accuracy ◽  
Compensation Method ◽  
Iteration Parameter ◽  
Stretch Bending ◽  
Compensation Factor ◽  
The Difference ◽  
Specific Material ◽  
Springback Control ◽  
Number Of Iterations

An unavoidable problem in the stretch-bending process is springback, which dictates the shape and dimensional accuracy of the product. This problem can be solved by adjusting the geometry of the die or through active process control. This study focuses on the design of the die shape to achieve the target product. Based on the fixed-point iterative method and displacement adjustment (DA) method, this paper proposes an iterative compensation method, which has a higher convergence rate, lower number of iterations, and higher precision compared to the DA method with only one control parameter. In addition, like the DA method, the proposed method does not depend on the material properties or mechanical model, but the difference is that it can quickly and effectively find out the iteration parameter, determine whether the parameter has convergence or not, and has no compensation factor. According to the deviation of iterative parameters between the value after stretch bending and the target value, the iterative compensation method can be used to calculate the compensation magnitude and compensation direction of the iterative parameter. For stretch-bending processes with invariable- and variable-curvature die shapes, the convergence of control parameters is verified mathematically with the convergence theorem of the method, and experiments are conducted to verify the iterative compensation method. The experimental results show that the target products can be obtained with a small number of iterations without knowing the specific material properties.

scholarly journals Analysis on the Difference of Impact Response between Single Coal-Rock Particle and the Box Structure-Based Tail Beam

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Li-rong Wan ◽  
Zhe Li ◽  
Yang Yang ◽  
Ran Li
Keyword(s):  
Theoretical Model ◽  
Contact Zone ◽  
Metal Plate ◽  
Contact Mode ◽  
Impact Speed ◽  
Rock Particle ◽  
Box Structure ◽  
Coal Rock ◽  
The Difference ◽  
The Impact

In the process of coal caving, the basis of identifying coal and rock by the vibration signal is the difference of the tail beam response when coal-rock impacts the tail beam, and the tail beam in the hydraulic support is a complex box structure with multiplate transverse and longitudinal welding, and the response difference of the box structure-based tail beam under the impact of coal-rock is not clear. Therefore, this paper studies the response difference of box structure-based tail beam when coal-rock particle impacts on the box structure-based tail beam. Firstly, through the construction and analysis of the impact theoretical model of the coal-rock particle and metal plate, it is found that the complex box structure of the tail beam makes it extremely difficult to establish the impact theoretical model of the coal-rock and box structure-based tail beam, so it is impossible to directly study the response of the box structure-based tail beam when the coal-rock impacts on the box structure-based tail beam by the theoretical method. Therefore, the impact simulation model of coal-rock particle and box structure-based tail beam is further established. Through the changes of kinetic energy and internal energy of the box structure-based tail beam system, the contact response of collision contact zone, and noncollision contact zone of the box structure-based tail beam, the response difference of box structure-based tail beam when coal-rock particle impacts on the box structure-based tail beam is analyzed. Then, by changing the impact speed and contact mode of the coal-rock particle, the effects of impact speed and the contact mode on the response difference of the box structure-based tail beam are studied separately. The conclusion shows that the response difference of the box structure-based tail beam under the impact of the coal particle and rock particle is obvious, and the difference increases as the impact speed increases, and the difference increases as the contact range increases.

scholarly journals Keyframe Selection of Frame Similarity to Generate Scene Segmentation Based on Point Operation

2018 ◽  
Vol 8 (5) ◽  
pp. 2839
Author(s):  
Wisnu Widiarto ◽  
Mochamad Hariadi ◽  
Eko Mulyanto Yuniarno
Keyword(s):  
Correction Factor ◽  
Video Segmentation ◽  
Signal To Noise Ratio ◽  
Gamma Correction ◽  
Signal To Noise ◽  
Distance Difference ◽  
Pixel Value ◽  
Noise Ratio ◽  
The Difference ◽  
Original Frame

<span lang="EN-US">Video segmentation has been done by grouping similar frames according to the threshold. Two-frame similarity calculations have been performed based on several operations on the frame: point operation, spatial operation, geometric operation and arithmatic operation. In this research, similarity calculations have been applied using point operation: frame difference, gamma correction and peak signal to noise ratio. Three-point operation has been performed in accordance with the intensity and pixel frame values. Frame differences have been operated based on the pixel value level. Gamma correction has analyzed pixel values and lighting values. The peak signal to noise ratio (PSNR) has been related to the difference value (noise) between the original frame and the next frame. If the distance difference between the two frames was smaller then the two frames were more similar. If two frames had a higher gamma correction factor, then the correction factor would have an increasingly similar effect on the two frames. If the value of PSNR was greater then the comparison of two frames would be more similar. The combination of the three point operation methods would be able to determine several similar frames incorporated in the same segment</span>

The Origin of the Moon

1962 ◽  
Vol 14 ◽  
pp. 149-155 ◽  
Author(s):  
E. L. Ruskol
Keyword(s):  
Chemical Composition ◽  
Solar System ◽  
The Moon ◽  
The Earth ◽  
The Difference ◽  
Origin Of The Moon

The difference between average densities of the Moon and Earth was interpreted in the preceding report by Professor H. Urey as indicating a difference in their chemical composition. Therefore, Urey assumes the Moon's formation to have taken place far away from the Earth, under conditions differing substantially from the conditions of Earth's formation. In such a case, the Earth should have captured the Moon. As is admitted by Professor Urey himself, such a capture is a very improbable event. In addition, an assumption that the “lunar” dimensions were representative of protoplanetary bodies in the entire solar system encounters great difficulties.

Influence of Cell Wall Composition on the Fossilisation of Bacteria and the Implications for the Search for Early Life Forms

1997 ◽  
Vol 161 ◽  
pp. 491-504 ◽  
Author(s):  
Frances Westall
Keyword(s):  
Cell Wall ◽  
Life Forms ◽  
Cation Binding ◽  
Positive Bacterium ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Transmission Electron ◽  
Hydrothermal Sediments ◽  
Identification Of Bacteria ◽  
The Difference

AbstractThe oldest cell-like structures on Earth are preserved in silicified lagoonal, shallow sea or hydrothermal sediments, such as some Archean formations in Western Australia and South Africa. Previous studies concentrated on the search for organic fossils in Archean rocks. Observations of silicified bacteria (as silica minerals) are scarce for both the Precambrian and the Phanerozoic, but reports of mineral bacteria finds, in general, are increasing. The problems associated with the identification of authentic fossil bacteria and, if possible, closer identification of bacteria type can, in part, be overcome by experimental fossilisation studies. These have shown that not all bacteria fossilise in the same way and, indeed, some seem to be very resistent to fossilisation. This paper deals with a transmission electron microscope investigation of the silicification of four species of bacteria commonly found in the environment. The Gram positiveBacillus laterosporusand its spore produced a robust, durable crust upon silicification, whereas the Gram negativePseudomonas fluorescens, Ps. vesicularis, andPs. acidovoranspresented delicately preserved walls. The greater amount of peptidoglycan, containing abundant metal cation binding sites, in the cell wall of the Gram positive bacterium, probably accounts for the difference in the mode of fossilisation. The Gram positive bacteria are, therefore, probably most likely to be preserved in the terrestrial and extraterrestrial rock record.

Structuring, Motions and Shapes of Corona Emission Line Profiles

1994 ◽  
Vol 144 ◽  
pp. 421-426
Author(s):  
N. F. Tyagun
Keyword(s):  
Emission Line ◽  
Filling Factor ◽  
Direct Relationship ◽  
Coronal Plasma ◽  
Line Of Sight ◽  
Line Profiles ◽  
The Difference ◽  
Yellow Line ◽  
Red Line

AbstractThe interrelationship of half-widths and intensities for the red, green and yellow lines is considered. This is a direct relationship for the green and yellow line and an inverse one for the red line. The difference in the relationships of half-widths and intensities for different lines appears to be due to substantially dissimilar structuring and to a set of line-of-sight motions in ”hot“ and ”cold“ corona regions.When diagnosing the coronal plasma, one cannot neglect the filling factor - each line has such a factor of its own.

Difference Fourier Analysis of Glucose Embedded and Frozen Hydrated Purple Membrane

1982 ◽  
Vol 40 ◽  
pp. 74-75
Author(s):  
Jules S. Jaffe ◽  
Robert M. Glaeser
Keyword(s):  
Purple Membrane ◽  
Data Set ◽  
High Resolution Data ◽  
X Ray ◽  
X Ray Crystallography ◽  
Fourier Techniques ◽  
Versus Protein ◽  
The Difference ◽  
Difference Fourier ◽  
Ideal Method

Although difference Fourier techniques are standard in X-ray crystallography it has only been very recently that electron crystallographers have been able to take advantage of this method. We have combined a high resolution data set for frozen glucose embedded Purple Membrane (PM) with a data set collected from PM prepared in the frozen hydrated state in order to visualize any differences in structure due to the different methods of preparation. The increased contrast between protein-ice versus protein-glucose may prove to be an advantage of the frozen hydrated technique for visualizing those parts of bacteriorhodopsin that are embedded in glucose. In addition, surface groups of the protein may be disordered in glucose and ordered in the frozen state. The sensitivity of the difference Fourier technique to small changes in structure provides an ideal method for testing this hypothesis.

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