Theoretical Basis and Technology Development of the Combined Process of Asymmetric Rolling and Plastic Bending

2012 ◽  
Vol 586 ◽  
pp. 259-264 ◽  
Author(s):  
Mikhail Sverdlik ◽  
Alexander Pesin ◽  
D.O. Pustovoytov
Keyword(s):  
Theoretical Basis ◽  
Technology Development ◽  
Dynamic Loads ◽  
Asymmetric Rolling ◽  
Plastic Bending ◽  
Combined Process ◽  
Friction Forces ◽  
Order Curve ◽  
The Moment ◽  
Rolling Technology

The article focuses at technology development of the vertical asymmetric rolling and combined process of vertical asymmetric rolling and plastic bending. It has been shown that vertical asymmetric rolling peculiarity relates to the presence of a mixed zone, in which friction forces on contact roll surfaces are directed are differently. Experimental research showed serious drawbacks in the rolling technology caused by the growth of dynamic loads arising at the moment of plate contact with the bending roller. For solving the problem it was proposed to make the roller position motile to allow its movement along the required trajectory. The application of the motile roller helps to reduce dangerous torque differentiation at working rolls by the value of 1,5-2,5 compared with the rigidly fixed roller. The most effective bending roller trajectory is a second-order curve that is convex parabola.

Technology Development of Large-Size Bodies Manufacturing from Thick Plate Materials Based on Combined Methods of Deformation

2016 ◽  
Vol 685 ◽  
pp. 375-379 ◽  
Author(s):  
Alexander Pesin ◽  
Ernst Drigun ◽  
D.O. Pustovoytov ◽  
Ilya Pesin
Keyword(s):  
Thick Plate ◽  
Technology Development ◽  
Sheet Thickness ◽  
Technological Parameters ◽  
Asymmetric Rolling ◽  
Plastic Bending ◽  
Second Stage ◽  
Large Size ◽  
Third Stage ◽  
Three Stages

The main goal of the investigation is to determine key technological parameters, necessary for producing required curvature of sheets up to 4000 mm in width with the required mechanical properties. Investigation into dynamics of the process' main technological parameters allowed it to define its three characteristic stages: asymmetric rolling, asymmetric rolling in combination with initial unsettled plastic bending, and asymmetric rolling combined with settled plastic bending. It was found out that the intensity of the deformations changes unevenly, depending on the height of the deformation zone, on all three stages, with its highest value being in the lower part of the sheet, and with the lowest value being in its center. In the second stage, the intensity of the deformation abruptly increases, and a significant asymmetry on the sheet thickness occurs. In the third stage, the non-uniformity of the intensity deformations fields decreases. Similar results can be also observed for stress intensities. Casings on two converters were produced and installed in the oxygen-converter plant.

The Influence of the Suspension on the Phenomena of Wheel-Rail Contact

2015 ◽  
Vol 809-810 ◽  
pp. 1061-1066
Author(s):  
Ioan Sebeşan ◽  
Valeriu Ştefan
Keyword(s):  
Contact Surface ◽  
Contact Problems ◽  
Contact Forces ◽  
Dynamic Loads ◽  
Friction Forces ◽  
Normal Contact ◽  
The Moment ◽  
The Relationship ◽  
Contact Pressures ◽  
Pivoting Friction

Efficient use of adhesion between wheels and rails involves a good knowledge of this phenomenon, in order to equip the vehicle with adequate facilities and systems that protect the vehicle and the rail. The loading of the vehicle's axle with dynamic loads in vertical and horizontal planes, are to be developed in the area of contact, both normal stress and shear distributed stress, their sum giving the friction force and the moment of pivoting friction (spin). This makes the wheel-rail contact problems take the two aspects of the study, namely the problem of normal and tangential contact issue. The normal contact problem involves regular geometric shape bodies, determining the size of the resulting contact surface, the distribution of the normal contact pressures and the relationship between the proximity of the bodies and the normal contact force. Solving the problem of the tangential wheel-rail contact is about to establish the correlation between the creepage, normal contact forces and friction forces, and also the ratio between the adherent contact surface and the nominal contact surface where the creepage ocurs.

scholarly journals Impact Coefficient Analysis of Curved Box Girder Bridge Based on Vehicle-Bridge Coupling

2022 ◽  
Vol 2022 ◽  
pp. 1-11
Author(s):  
Fei Guo ◽  
Heng Cai ◽  
Huifang Li
Keyword(s):  
Shear Force ◽  
Primary Beam ◽  
Dynamic Loads ◽  
Box Girder ◽  
Impact Coefficient ◽  
Force Impact ◽  
Girder Bridge ◽  
The Moment ◽  
The Impact ◽  
Load Weight

In the current vehicle-bridge dynamics research studies, displacement impact coefficients are often used to replace the moment and shear force impact coefficients, and the vehicle model is also simplified as a moving-load model without considering the contribution of vehicle stiffness and damping to the system in some concerned research studies, which cannot really reflect the mechanical behavior of the structures under vehicle dynamic loads. This paper presents a vehicle-bridge coupling model for the prediction of dynamic responses and impact coefficient of the long-span curved bending beam bridge. The element stiffness matrix and mass matrix of a curved box girder bridge with 9 freedom degrees are directly deduced based on the principle of virtual work and dynamic finite element theory. The vibration equations of vehicle-bridge coupling are established by introducing vehicle mode with 7 freedom degrees. The Newmark-β method is adopted to solve vibration response of the system under vehicle dynamic loads, and the influences of flatness of bridge surface, vehicle speed, load weight, and primary beam stiffness on the impact coefficient are comprehensively discussed. The results indicate that the impact coefficient presents a nonlinear increment as the flatness of bridge surface changes from good to terrible. The vehicle-bridge coupling system resonates when the vehicle speeds reach 60 km/h and 100 km/h. The moment design value will maximally increase by 2.89%, and the shear force design value will maximally decrease by 34.9% when replacing moment and shear force impact coefficients with the displacement impact coefficient for the section internal force design. The load weight has a little influence on the impact coefficient; the displacement and moment impact coefficients are decreased with an increase in primary beam stiffness, while the shear force impact coefficient is increased with an increase in primary beam stiffness. The theoretical results presented in this paper agree well with the ANSYS results.

The Origins of Formation of Descriptive Geometry

2021 ◽  
pp. 3-11
Author(s):  
N. Sal'kov
Keyword(s):  
Population Growth ◽  
Middle Ages ◽  
Theoretical Basis ◽  
Descriptive Geometry ◽  
Orthogonal Projections ◽  
Cave Wall ◽  
Ancient Times ◽  
The Moment ◽  
Special Case ◽  
Living Area

The translation "Descriptive geometry" is not entirely accurate. In fact, the phrase should be translated as "Narrative geometry". Based on this translation, it can be confidently stated that the science under consideration serves not only as a theoretical basis for orthogonal projections, a special case of which are ordinary drawings, but also for any images – in this the author of the article fully agrees with such authorities as N.A. Rynin, N.F. Chetverukhin, V.O. Gordon, S.A. Frolov, N.A. Sobolev and many others. The paper considers the origins of one of the directions of geometry – descriptive geometry. The hypothesis is put forward that in reality descriptive geometry, or rather, its elements, was originally involved in ancient times, during the primitive communal system when making drawings on the walls of caves and rocks. Orthogonal projections were used in the ancient world and in the Middle Ages, and Gaspard Monge at the end of the XVIII century systematized all the existing disconnected developments on descriptive geometry, adding his own research. Most likely, geometry in general was the very first science that originated when our ancestors who lived in caves faced the problem of increasing the living area due to population growth. And descriptive geometry began to develop from the moment when the first artist depicted scenes from life on the cave wall: hunting, fishing, tribal wars, events that shocked people, etc. Ancient artists existed on all continents of the globe, except perhaps Antarctica, since rock carvings were found on all other continents. And the earliest was performed somewhere 25-30 thousand years ago. Thus, the hypothesis that the elements of descriptive geometry originated in the primitive communal system can be considered proven.

scholarly journals Mathematical Modeling of Impact of Possible Shock Dynamic Loads on the Modern Composite Materials

2019 ◽  
Vol 224 ◽  
pp. 02012
Author(s):  
Eugenе Sosenushkin ◽  
Oksana Ivanova ◽  
Elena Yanovskaya ◽  
Yuliya Vinogradova
Keyword(s):  
Composite Materials ◽  
Friction Force ◽  
Equations Of Motion ◽  
Elastic Fiber ◽  
Dynamic Loads ◽  
Friction Forces ◽  
Absolute Value ◽  
A Value ◽  
The Absolute ◽  
The Impact

In this paper, we study the dynamic processes in materials reinforced with fibers, that can be represented as composite rods. There has been developed a mathematical model of wave propagation under the impact of a shock pulse in semi-infinite composite rods. It is believed that the considered composite rod consists of two layers formed by simpler rods of different isotropic materials with different mechanical properties. The cross sections of such rods are considered to be constant and identical. When such composite materials are impacted by dynamic loads, a significant part of the energy is dissipated due to the presence of friction forces between the contact surfaces of the rods. In this regard, we study the propagation of waves in an elastic fiber-rod, the layers of which interact according to Coulomb law of dry friction. The case of instantaneous excitation of rods by step pulses is investigated. The blow is applied to a rod made of a harder material. In the absence of slippage, the friction force gets a value not exceeding the absolute value of the limit. In the absence of slippage, the friction force takes a value not exceeding the absolute value of the limit. Let us consider the value of the friction force constant. Normal stresses and velocities satisfy the equations of motion and Hooke’s law. The problem statement results in the solution of inhomogeneous wave equations by the method of characteristics in different domains, which are the lines of discontinuities of the solution. Solutions are found in all constructed domains. On the basis of the analysis of the obtained solution, qualitative conclusions are made and curves are constructed according to the obtained ratios. From the found analytical solution of the problem it is possible to obtain ratios for stresses and strain rates in composite rods and composite materials.

scholarly journals Influence of technological process parameters on equipment dynamic factor

2021 ◽  
Vol 3 (134) ◽  
pp. 3-12
Author(s):  
Oleksii Hrechanyi ◽  
Tatiana Vasilchenko ◽  
Andrii Vlasov ◽  
Eduard Huz ◽  
Daria Tsimakhovych
Keyword(s):  
Functional Equation ◽  
Technological Process ◽  
Metallurgical Industry ◽  
Rolling Process ◽  
Equation Of Motion ◽  
Dynamic Loads ◽  
Dynamic Factor ◽  
Technological Equipment ◽  
Preliminary Calculation ◽  
The Moment

Technological equipment of the metallurgical industry operates in difficult conditions in terms of dynamic loads. On the other hand, special requirements are imposed on their mechanisms - they must be reliable in operation and allow easy regulation, and in the event of breakdowns, allow quick replacement or repair of units and parts, and at the same time must meet the conditions for the accuracy of reproduction of the given technological opera-tions.In modern rolling shops, technological operations are carried out according to the continuous and continuous principles of creating new rolling equipment and the operation of complex machines requires the use of achievements in various fields of science and technology. Scissors, straightening machines, coilers, uncoilers, tilters, manipulators, pushers, conveyors are built into the flow technological working lines. And the performance of the technological line as a whole depends on the coordinated work of these mechanisms.The issues of dynamic loads from the point of view of the interaction of the rolling stands of the continuous broadband mill 1680 have been considered rather thoroughly, while the effect of changing the technological modes of rolling on the equipment of the current line, in particular the coiler, is not covered.In order to reduce equipment downtime due to emergency failures associated with an increase in dynamic loads from incorrectly selected technological modes, the task was set to analytically study the effect of a change in the rolling process on the dynamism coefficient using the example of roller coilers of rolling mills.To analyze the forced vibrations arising in the drive of the reel drum of the mill 1680, a two-mass torsion system is considered, to which external moments are applied - the moment of the technological resistance of the working body, reduced to the motor shaft, and the nominal torque of the electric motor.On the basis of the considered calculation scheme, a functional equation of motion was compiled through which the relationship between the change in the parameters of the technological process and the coefficient of dynamism was established.The solution of the functional equation of motion makes it possible to establish the value of the moment of elastic forces as a function of time, which is used in calculating the dynamic coefficient, which in turn characterizes the dynamic loads on the nodes of technological equipment. Its preliminary calculation allows avoiding emergencies associated with equipment failure in case of incorrect selection of the technological process modes.

scholarly journals Investigation of the influence of hot asymmetric long products on the formation of the microstructure, mechanical properties and service characteristics of finished products

2019 ◽  
pp. 156-172
Author(s):  
V.G. Razdobreev ◽  
D.G. Palamar
Keyword(s):  
Mechanical Properties ◽  
Carbon Steel ◽  
Dislocation Density ◽  
Rolling Force ◽  
Diffraction Method ◽  
Rolling Process ◽  
Crystalline Lattice ◽  
Asymmetric Rolling ◽  
Rolling Shear ◽  
Rolling Technology

The aim of the work is to study the influence of the process of hot asymmetric rolling on the structural state, mechanical properties and operational characteristics of long products of simple form from ordinary carbon steel. To simulate the process of asymmetric high-quality rolling, the mathematical model previously developed in the ISI added the possibility of taking into account cases of rolling in a pair of rolls of different diameters, rolling in a pair of rolls of different materials, rolling with one drive and one non-drive rolls, rolling at different speeds in a pair of rolls and other. The calculations showed a reduction in rolling force to 10 % with an asymmetric rolling process compared to the traditional rolling process. The study of the features of the process of hot asymmetric rolling (shear rolling) compared with the traditional rolling process was carried out under industrial conditions in the production of a 12x12 mm square profile from ordinary low-carbon steel St3sp. It was found that the average values of HRB, σВ, and σТ in the studied samples practically do not differ, and the average values of δ5 are higher by 8 % (abs.) or ~ 27 % (rel.) In samples that were rolled using the asymmetric rolling technology than in samples that were rolled using traditional rolling technology. The estimation of dislocation density by the X-ray diffraction method showed that during hot asymmetric rolling, the dislocation density is reduced by ~ 46% due to the active flow of in-situ polygonization and recrystallization processes during deformation. In this case, the average values of the microfractures of the crystalline lattice of ferrite are 21% lower in the samples obtained by the method of asymmetric rolling than in the samples obtained by traditional rolling. For the first time, a decrease in the total atmospheric corrosion rate was found in samples that were rolled using asymmetric rolling technology (0.39 g/m2xh) compared to samples that were rolled using traditional rolling technology (0.445 g/m2xh).

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