Analytical research of steel rope dynamic properties

Transverse and rotational vibrations of steel rope are important issues in various technical installations. Dynamic properties of rope fragment are also useful as diagnostic parameters for broken wire detection within steel rope. This paper is intended to research the steel rope dynamic properties using lumped mass model. Theoretical detection of desired natural frequencies and corresponding forms of axially tensed rope fragment is useful for the proposed method implementation. The proposed theoretical model is verified with results of experimental research of steel rope. The proposed model is focused on transversal and rotational rope vibration analysis; there is an aim to obtain rotational vibration shape of rope from excitation in transversal direction to rope axis. Obtained theoretically calculated amplitude-frequency characteristics are compared with experimentally measured and good coincidence noticed. Finally, conclusions are drawn on the performed rope modelling results

Analytical research of steel rope dynamic properties

Transverse and rotational vibrations of steel rope are important issues in various technical installations. Dynamic properties of rope fragment are also useful as diagnostic parameters for broken wire detection within steel rope. This paper is intended to research the steel rope dynamic properties using lumped mass model. Theoretical detection of desired natural frequencies and corresponding forms of axially tensed rope fragment is useful for the proposed method implementation. The proposed theoretical model is verified with results of experimental research of steel rope. The proposed model is focused on transversal and rotational rope vibration analysis; there is an aim to obtain rotational vibration shape of rope from excitation in transversal direction to rope axis. Obtained theoretically calculated amplitude-frequency characteristics are compared with experimentally measured and good coincidence noticed. Finally, conclusions are drawn on the performed rope modelling results

Dynamic reaction forces of an overhead crane on lifting

In the recent period, girder bridge cranes are replaced with double-beam overhead cranes with a rectangular cross-section of the beams. In addition, new materials are used for producing them thus applying other values of allowable loads and deformations. The paper focuses on two overhead cranes working for JSC Vilniaus kranai (Vilnius Cranes). The presented mathematical model provides an opportunity to assess the structural peculiarities of the above introduced cranes. The calculated results of dynamic loads appearing in the beginning and the end of the lifting process and having an impact on the lifting mechanism and metal structure are provided in the article

An Investigation Into Fault Diagnosis in a Rotor-Bearing System with Dampers Used in Centrifugal Milk Separators

This paper deals with the problems encountered in the fault diagnosis in damped rotor-bearing systems used in centrifugal milk separators. It is shown that direct bearing vibration measurements are more reliable than indirect (through rotor housing) vibration measurements. However, in most cases it is not possible to measure bearing vibrations directly. The factors causing large diagnostic measurement errors, such as the influence of the vibration damping system, step-up gear and electric motor noise are discussed in the paper. It is established that vibration measurements of the damping system are noninformative and cannot be used to diagnose faults in bearings. It is proposed to use the vibration spectra correlation to predict bearing failures in rotor-bearing systems of this type

The investigation of dynamics of misaligned units in vehicle transmission

In the article the problems related to the dynamics of a mechanic system on misalignment of shafts in radial direction are presented. The object of the investigation is a two-shaft system connected with an elastic centrifugal ring coupling. Using equations of static equilibrium it was found that an internal moment of resistance to rotation appears in the coupling connecting the radially misaligned shafts. Using Dalamber's principle for the rotational movement the differential equation that describes the rotation of the second shaft has been developed. It was shown that after the perfonnance of the corresponding actions and the introduction of a new variable the said equation is transformed in to an equation which character virtually coincides with the equation describing free oscillations of a mathematical pendulum. Because the value of misalignment of shafts in the radial direction is small in comparison with other parameters, a small parameter method was used for the solution of this equation. The found solutions show that rotational vibrations with the double frequency of rotational movement are excited in the misaligned mechanical system with an elastic centrifugal ring coupling. The restrictions ofthe application of a small parameters method have been explored and the limits of its application have been found. First Published Online: 19 Dec 201

Mechanizmų mechanika ir elementai

Mechanizmų mechanikos ir elementų laboratorinių ir pratybų darbų rinkinyje pateikiami laboratorinių ir pratybų darbų aprašymai, atitinkantys pagrindinių studijų MEPMB11410 modulio reikalavimus. Šie aprašymai, juose esantys metodiniai nurodymai skirti Transporto inžinerijos fakultetų dieninio ir ištęstinio skyriaus studentams, studijuojantiems mechanizmų mechanikos ir elementų kursą. Leidinys parengtas ir išleistas už Europos struktūrinių fondų lėšas, jomis finansuojant VGTU Transporto inžinerijos, Biomechanikos ir Aviacinės mechanikos inžinerijos projektą „Studijų programų atnaujinimas pagal ES reikalavimus, gerinant studijų kokybę ir taikant inovatyvius studijų metodus“ pagal Lietuvos 2007–2013 m. Žmogiškųjų išteklių veiksmų programos 2 prioriteto „Mokymasis visą gyvenimą“ VP1-2.2-ŠMM-07-K priemonę „Studijų kokybės gerinimas, tarptautiškumo didinimas“. Projekto kodas Nr. VP1-2.2-ŠMM 07-K-01-023, finansavimo ir administravimo sutartis Nr. VP1-2.2-ŠMM-07-K-01-023

Damping transversal vibrations of the offset cylinder of the offset press

Investigation into the influence of a dynamic vibration damper on the intensity of the absolute forced transversal vibrations of the blanket cylinder of the web printing offset press was performed. The analytical and numerical examination of the dynamic model of the cylinder was done. The obtained results have disclosed that the application of the damper decreases the intensity of printing cylinder vibrations. Article in Lithuanian. Ruloninės ofsetinės mašinos ofsetinio cilindro skersinių virpesių slopinimas Santrauka. Analiziniu ir skaitmeniniu būdu ištirtas dinaminio virpesių slopintuvo efektyvumas slopinant priverstinius periodinius ofsetinio spausdinimo įrenginio ofsetinio cilindro skersinius virpesius, bloginančius atspaudų kokybę. Atliktas ofsetinio cilindro ir virpesių slopintuvo modeliavimas „Matlab“ programa. Sudarytos „Simulink“ diagramos. Pateiktos amplitudinės dažninės charakteristikos. Parodyta, kad naudojant virpesių slopintuvus galima efektyviai mažinti spausdinimo įrenginio cilindrų skersinius virpesius. Raktiniai žodžiai: virpesių slopintuvas; ofsetinis cilindras; ofsetinės spausdinimo mašinos; skersiniai virpesia

The investigation of the folding quality in the printing house “BALTO“

In the paper the folding quality in the printing house “BALTO”is investigated. The concept of quality, paper folding process,combined folding machine parameters and printing papers aredescribed. In the paper the percent of folding defects is determined, the spoilage dependence on paper characteristics, foldingmachine settings and other factors are investigated. Resultswere presented as histograms and were analyzed using statistical methods. Article in Lithuanian. Lankstymo kokybės tyrimas UAB BALTO spaustuvėje Santrauka. Surinkta statistinė informacija apie UAB BALTO spaustuvėje lankstymo metu padaromą brokuotą produkciją. Stebėjimai atlikti dirbant su skirtingomis popieriaus rūšimis ir popieriaus gramatūromis. Gauti rezultatai buvo pateikti histogramomis, kurios analizuojamos pasitelkiant statistinius metodus. Vertinant rezultatus, papildomai buvo sudaryta statistinių skirstinių lentelė. Nustatyta, kurios popieriaus rūšys ir gramatūros lankstomos kokybiškiau ir kokios popieriaus charakteristikos tai lemia. Reikšminiai žodžiai: popierius, popieriaus charakteristikos, lankstymas, brokas

Impact of contact rings in plate and blanket cylinders of printing section’s drive on its dynamic accuracy

In drives of printing section of modern web double-side printing presses, contact steel rings are attached at end of plate and blanket cylinders that press the cylinders against each other on their rotation. The amplitudefrequency response of rotational vibrations of the plate and blanket cylinders, their natural frequencies and shapes of natural vibrations are discussed upon herein. It is found that in a general case the rings reduce an intensity of the vibrations, however, ther impact is not unambiguously positive: the rings reduce relative vibrations between the plate and blanket cylinders, however, they increase the vibrations between the blanket cylinders where a print passes

Investigation into delamination

The paper investigates the process of delaminatinon. The carried out test included seven grades of paper and two types of lamination films (gloss and mat). Delamination was investigated at different ink coverage making from 400% to 90%. It was established that delamination was influenced by the properties of the paper, ink drying time, ink coverage, the type of a lamination film and folding direction. The optimal dependence of the lamination film on printing combination was established. Article in Lithuanian Laminavimo plėvelės atšokimo tyrimas Santrauka Darbe aprašytas laminavimo plėvelės atšokimo tyrimas. Tirti naudotas septynių rūšių popierius, dviejų rūšių laminavimo plėvelė (blizgi ir matinė). Plėvelės atšokimas tirtas skirtingų dažų plote – nuo 400 % iki 90 %. Tiriant nustatyta, kad plėvelei atšokti įtakos turi popieriaus savybės, dažų džiūvimo laikas, dažų plotas, laminavimo plėvelės rūšis, popieriaus lankstymo kryptis. Nustatytos optimalios laminavimo plėvelės priklausomybės nuo atspaudų kombinacijos. Reikšminiai žodžiai: laminavimo plėvelė, bandinio paruošimas, popieriaus rūšys, lankstymo kryptis, bigavimas, laminavimo plėvelės atšokimas