scholarly journals Jaw crushers equipped with elastic pneumatic elements in joints of kinematic pairs

2020 ◽  
Vol 63 (2) ◽  
pp. 166-168 ◽  
Author(s):  
A. G. Nikitin ◽  
A. V. Abramov ◽  
I. A. Bazhenov

The article describes the reason of additional dynamic forces occurrence in course of operation of the lever mechanism of jaw swivel drive with gaps in hinges reducing reliability of jaw crushers operation. Gaps sampling mechanisms are equipped with elastic pneumatic elements. These pneumatic elements throughout the entire cycle of the crank-beam mechanism constantly act on the movable body with an anti-friction liner mounted on it. Mechanisms for gaps sampling provide a choice of the gap in the joints of kinematic pairs, prevent the appearance of additional dynamic loads, and reduce the level of vibration of the mechanical system. It has been experimentally established that usage of such mechanisms increases reliability of jaw crushers.

Author(s):  
S. R. Rakhmanov ◽  
V. V. Povorotnii

To form a necessary geometry of a hollow billet to be rolled at a pipe rolling line, stable dynamics of the base equipment of the automatic mill working stand has a practical meaning. Among the forces, acting on its parts and elements, significant by value short-time dynamic loads are the least studied phenomena. These dynamic loads arise during transient interaction of the hollow billet, rollers, mandrel and other mill parts at the forced grip of the hollow billet. Basing of the calculation scheme and dynamic model of the mechanical system of the ТПА 350 automatic mill working stand was accomplished. A mathematical model of dynamics of the system “hollow billet (pipe) – working stand” within accepted calculation scheme and dynamic model of the mechanical system elaborated. Influence of technological load of the rolled hollow billet variation in time was accounted, as well as variation of the mechanical system mass, and rigidity of the ТПА 350 automatic mill working stand. Differential equations of oscillation movement for four-mass model of forked sub-systems of the automatic mill working stand were made up, results of their digital calculation quoted. Dynamic displacement of the stand elements in the inter-roller gap obtained, which enabled to estimate the results of amplitude and frequency characteristics of the branches of the mill rollers setting. It was defined by calculation, that the maximum amplitude of the forced oscillations of elements of the ТПА 350 automatic mill working stand within the inter-roller gap does not exceed 2 mm. It is much higher than the accepted value of adjusting parameters of the deformation center of the ТПА 350 automatic mill. A scheme of comprehensive modernization of the rollers setting in the ТПА 350 automatic mill working stand was proposed. It was shown, that increase of rigidity of rollers setting in the ТПА 350 automatic mill working stand enables to stabilize the amplitude of forced oscillations of the working stand elements within the inter-rollers gap and considerably decrease the induced nonuniform hollow billet wall thickness and increase quality of the rolled pipes at ТПА 350.


2018 ◽  
Vol 224 ◽  
pp. 02009
Author(s):  
Anton Kurochkin ◽  
Vladimir Vagin ◽  
Anton Karpesh ◽  
Natalja Dyorina

The article presents the results of the control system development for the electro hydraulic drive of a mobile sinking hoisting plant. Increasing the technical performance of mobile sinking hoisting plants is possible by increasing their productivity, reducing their massiveness and increasing the durability of tractional organs and a number of units and parts of lifting machines. However, the increase in productivity, in its turn, causes the need to increase the suspended load on the traction organs, which causes a significant increase of the dynamic loads in the elastic elements in the transient operation modes of the hoisting plant. One of the ways to reduce constantly acting dynamic loads of vibration character is the use of a gearless hydraulic drive with damping properties. But, nevertheless, the hydraulic drive possibilities are limited for large vibration amplitudes of dynamic forces. The damping properties of the hydraulic drive can be increased by using control system, which allows realizing effective control of the electro hydraulic drive of the hoisting plant.


2013 ◽  
Vol 597 ◽  
pp. 199-205
Author(s):  
Bartosz Zdunek ◽  
Michał Landowski ◽  
Stanislaw Taryma ◽  
Ryszard Woźniak ◽  
Krystyna Imielińska ◽  
...  

Most important features of the child seat were presented. There was made analysis of selected dynamic loads acting on mannequins heads during a collision. Comparison of loads acting on the kid in a child seat and the other passengers in a car is presented. In analysis of the results particular attention has been paid on the children's secure in a car. The phenomena of collision child's occipital bone with seat backrest was described. There were presented results of dynamic test of chosen kind of materials, which were expected for having good energy absorbing characteristic. Selected courses of dynamic forces, values of peak forces and time of dynamic forces acting for tested materials were shown. The tests were made on dynamic droptower impact system Instron CEAST 9310.


2020 ◽  
Vol 11 (4) ◽  
pp. 89-94
Author(s):  
M. M. Korobko ◽  

Improving the reliability of structures of transport mechanisms and other elements, reducing metal content, improving performance, expanding functionality and technical capabilities is a priority area of work to improve existing and develop new machines for beet growing. The dynamic model of the chain conveyor which considers the basic movement and fluctuations of elements of the drive and a working cloth is developed in work. The model is represented by a system of discrete masses with eight degrees of freedom. The operation of chain conveyors is characterized by the presence of dynamic forces arising from the pulsating movement of the chain at a steady rotation of the drive sprocket. At the start-up site, dynamic forces from increasing the speed from zero to a certain constant value are added to these forces. Under such conditions, significant alternating dynamic loads can occur in the chain, which as a result of the accumulation of fatigue phenomena can lead to its premature destruction.


2020 ◽  
Vol 12 (3) ◽  
pp. 410-417
Author(s):  
Viktor GUTAREVICH ◽  
◽  
Marina KONDRATENKO ◽  

During the operation of the mine suspension monorail track and traction device form a mechanical system experiencing high dynamic loads associated with implementation of traction and braking forces. Emerging dynamic loads lead to formation of elastic deformations and oscillations that cause vibrations, which leads to displacement of drive wheels and reduces the implementation of traction. The study of the dynamics of traction device is an important step in improving safety and reliability of monorail transport. The aim of the work is to study dynamics of a friction-type traction device moving along a suspended monorail to assess influence of parameters of the elements of device on the vibrations and nature of interaction of drive wheels with monorail. Research methods. Mathematical modeling of the oscillatory processes resulting from interaction of the running gear of the traction device with the monorail is used. Stages of research include drawing up a design diagram oscillations of drive wheels of the traction device interacting with the monorail, developing a mathematical model for the analysis of vibrations caused by moving loads, also assessing the influence of structural parameters of mechanical system under consideration on nature of oscillations. Research results. The developed mathematical model of friction-type traction device movement allows us to establish relationship between parameters of structural elements of its running gear and pressure mechanism, as well as nature of vibrations that arise. As a result, frequencies of the mechanical system under consideration and maximum deviations were found, which allows you to set optimal device parameters to increase traction and increase lifespan of monorail suspended roads. Findings. It was determined that the frequency range of vibration of drive wheels mainly corresponds to the mid-frequency local vibrations of 16–36 Hz. Increasing length of lever for fixing axles of wheels and reducing their radius leads to formation of low-frequency vibrations with a frequency of less than 15 Hz. When length of lever of drive wheels is more than 0.5 m, shoulder of the spring is more than 0.6 m and radius of drive wheels is less than 0.25 m, vibrations with frequencies below 5 Hz can occur. It was found that increasing the length of lever for securing spring increases the oscillation frequency of one drive wheel and reduces frequency of the other. The difference between these frequencies significantly affects changes in the pressure of the wheels against monorail. When difference between frequencies is more than 10–12 Hz, direction of load changes pulsed, with a maximum swing of 0.02 rad, which reduces formation of fatigue fractures of tire wheels, and moments of decrease and increase in pressing force have a negative effect on traction, leading to slippage of drive wheels. When difference between frequencies is less than 10–12 Hz, direction of the load changes sharply, with a maximum swing of 0.03 rad, which increases deformation and formation of fatigue fractures of tire wheels, and short moments of weakening and increase of pressing force, constituting 0.1–0.3 s does not have a significant negative effect on traction.


2016 ◽  
Vol 871 ◽  
pp. 3-8 ◽  
Author(s):  
Viktor Artiukh ◽  
Vladlen Mazur ◽  
Raghu V. Prakash

The article exposes contemporary materials and structures for metallurgy. Feasible increase of dynamic forces on the rolling machinery during rolling of billets with masses up to 20 t (Stand No.1 of CWM 1700 HR, «U.S. Steel Košice», Košice, Slovakia, and PJSC «Illich MMPP», Mariupol, Ukraine) is discussed. It is proved that weight of billet, velocities of metal delivery to working rolls and rolling significantly influence the dynamic loads during metal biting. The technical solutions are suggested which would allow the steady rolling process of billets with masses up to 20 t and prevent accidental failures of frame parts, chocks and main lines.


Author(s):  
Alexander Vasilyevich Bratchenko

Motivated urgency of the undertaking accounting-experimental studies tense-deformed conditions ofthe separate nodes and details of the energy installation diesel locomotive z diesel of the type D49, to whichin the first place follows to refer the crankshaft. Considered importance of the creation to mathematicalmodel, which allows on stage of the designing already or at modernizations forced much cylinders of thediesels to value the influence of the fluctuations turning moments on dynamic loads not only, which areformed in sections cylinder modules, but and on work mechanism distribution exhaust gas and presentingfuel in cylinder. The Presented description of the particularities of the shaping turning moments inmechanical system of the energy installing the diesel locomotive on base of the use the harmonious analysis.As example of the use designed mathematical model is brought row of the harmonicas, from which forms thecurve of the change turning moment in section of the crankshaft eighth cylinder module of the energyinstallation with diesel D49.


1988 ◽  
Vol 15 (1) ◽  
pp. 66-71 ◽  
Author(s):  
J. H. Rainer ◽  
G. Pernica ◽  
D. E. Allen

Dynamic forces were measured during walking, running, and jumping, using an instrumented platform. The results are expressed as sinusoidal force amplitudes normalized by the subject's weight and are plotted versus frequency. The maximum dynamic loads for walking were found to be nearly twice as large as those recommended in the 1983 Ontario Highway Bridge Design Code or the British Standard BS5400, and those for running or jumping, more than six times as large.Responses of footbridges are calculated using a simple formula based on the dynamic loading due to one person, the response of a simple span at resonance, and limited duration of excitation. Good agreement was obtained with the measured response of two 17 m experimental spans subjected to human excitation, for both the first and second harmonics of the step rate. The resonant vibrations of the spans can be substantially reduced by resonant dampers. Key words: footbridges, dynamic loads, dynamic response, design criteria, resonant dampers.


Author(s):  
Jerzy Marcinkiewicz ◽  
Krzysztof Karaskiewicz ◽  
Claes Joheman

The paper presents a Relap5 study of the influence of the centrifugal pump characteristics on the dynamic loads on piping system after power failure. Interpolated and experimental pump characteristics are used. The differences between the interpolated and measured pump curves, the general description of Relap5 model and results of calculations in form of selected time curves for rotational speed, volume flow, pressures and dynamic forces are presented and discussed. The analysis of the results shows that the maximal dynamic force on pipe section calculated with experimental pump curves can be up to 6 % higher than respective calculated using interpolated curves. However, it is not possible to determine to what extent the differences are caused by the interpolation itself or caused by the differences in the design of the centrifugal pumps. The latter since it differs more than 50 years between the pumps whose characteristics are used for interpolation and the pumps with corresponding experimental characteristics.


2019 ◽  
Vol 298 ◽  
pp. 00109 ◽  
Author(s):  
Aleksandr Tsyganov

The impact of rail transportation on road vehicles that are placed in flatcars is considered in the article. The features of piggyback transportation and the dynamic forces acting on road vehicles in railway rolling stock are determined. The change dependences of the values of dynamic forces for different masses of road vehicles in the longitudinal and transverse directions are established. It is concluded that road vehicles that are used in regular piggyback transportation will experience significant dynamic loads of structural elements, which requires monitoring of their technical condition. Consequently, the infrastructure of piggyback terminals that load and unload road vehicles onto railway rolling stock should include the availability of automobile service facilities.


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