Kolmefraktsioonilise vibrosõela tugikonstruktsiooni projekteerimine

Kuupäev

2021-05-12

Väljaande pealkiri

Väljaande ISSN

Köite pealkiri

Kirjastaja

Tallinna Tehnikakõrgkool

Kokkuvõte

Käesoleva lõputöö eesmärgiks oli projekteerida tugikonstruktsioon Spaleck Flip-Flow 3d Combi Screen kolmefraktsioonilisele vibrosõelale. Vibrosõel on osa jäätmete purustus- ja sorteerimisliinist, mis hakkab käitlema ehitus- ja lammutusjäätmeid. Konstruktsiooni projekteerimiseks tutvuti tehtud lahendustega ning otsutati, et konstruktsioon projekteeritakse HEB taladest, mis ühendatakse omavahel horisontaal- ja diagonaaltugedega. Kuju leidmiseks loodi esmane traatmudel. Seejärel asuti talasid dimensioneerima. Vertikaalsete talade dimensioneerimiseks kasutati talale mõjuvat paindemomenti, millele lisati konstruktsiooni algkõverusest tulenev horisontaalne jõud ning tala vastupandumomendiks arvutati 59.2 cm3. Vertikaaltaladeks valiti HEB140 tala, mille vastupanumoment nõrgemas sihis oli 79 cm3. Seejärel teostati kontrollarvutus nõtkele, kus leiti tala maksimaalne nõtkekandevõime. Leitud nõtkekandevõime 118456 N oli suurem talale mõjuvast vertikaaljõust 54700 N ning tala sobis. Järgnevalt joonestati konstruktsioon SolidWorks keskkonnas nõrgestatud mudelina HEB120 taladest, et geomeetriast tulenevad muutused kergemini märgatavad oleks. Seejärel asuti kuju optimeerima. Kuju optimeerimiseks kasutati ANSYS keskkonda, milles arvutati läbi mudeli erinevad konfiguratsioonid ning leiti kõige suurema omavõnkesagedusega ehk kõige jäigema geomeetriaga mudel. Vältimaks konstruktsiooni resonantsi sattumist leiti seadme töösagedusest 11.33 Hz tulenevalt konstruktsioonile lubatud omavõnkesagedused. Lubatud vahemikeks oli 15.1...18.9 Hz ja 8.1...9.1 Hz. Optimeeritud kujuga konstruktsiooni omavõnkesagedus oli 13.49 Hz, asendades vertikaaltalad peatükis 3.2 dimensioneeritud HEB140 taladega ning teostades uus arvutus saadi omavõnkesageduseks 14.9 Hz. Järgnevalt muudeti konstruktsiooni jäigemaks asendades vertikaaltalad HEB160, horisontaaltalad HEB140 ning muutes diagonaaltalades nelikant-toru 80x80x3 torult 80x80x6 toru vastu. Mudeli omavõnkesageduseks tuli 17.17 Hz. Olles leidnud konstruktsiooni lõpliku kuju ja talad, projekteeriti lõpuni kõik sõlmed. Erinevad talad ühendati poltliidetega, selleks keevitati talade otsa plaat, liidet muudeti jäigemaks tugevdusribi kasutamisega. Konstruktsioonis kasutati kinnitusvahenditena M16 8.8 klassi polte. Poltide sobivuse kontrolliks teostati kontrollarvutus kõige ohtlikumale sõlmele - nelikant-torust diagonaali ja vertikaaltala vahel. Leiti poldile mõjuv jõud 703 N ning poldi lõikekandevõime, milleks oli 24120 N. Kuna lõikekandevõime oli suurem, kui mõjuvad jõud, siis M16 poldid sobivad. Sõela kinnitamiseks konstruktsioonile projekteeriti talade otsa taldmik, kuhu sõela tugijalad toetuma hakkavad ning M12 poltidega kinnituvad. Tagamaks keevisliidete sobivus teostati kontrollarvutus kõige ohtlikematele sõlmedele, milleks olid keevisõmblus tala ja alusplaadi vahel ning nelikanttoru keevisõmblus otsaflantsi külge. Leiti keevisõmbluses maksimaalne lubatud pinge, milleks oli 57.7 N/mm2. Pinged mõlemas keevisõmbluses jäid alla lubatu, taldmikul esines maksimaalne pinge 1.2 N/mm2 ja diagonaaltoel 0.5 N/mm2. Majandusarvutustest leiti seadme projekteerimisele kuluv aeg ja ajast tulenev omahind. Projekteerimisele kulus 158 tundi ning projekteerimise hinnaks oli 30 eurot/tund. Omahinnaks kujunes 4740 eurot.


The aim on this thesis was to design a support structure for Spaleck Flip-Flow 3d Combi screen. The screen separates material into three different fractions, of which oversize and medium fraction will unloaded from chutes at the end of the screen and fine fraction will be unloaded under the screen. The screen is part of a sorting and crushing line which will is designed to handle construction and demolition waste. To begin the designing process of the structure, previous designs of similar supports were examined and a design, where the structure consists of vertical load-bearing beams joined by horizontal and diagonal supports was chosen. To visualize the design, a wire-frame model was created. To dimension needed beams a series of calculations were made to find the bending moment acting on the vertical beam. In this calculation horizontal forces from dynamic loads and forces from beam’s initial deviaton were taken into account. Based on the safety factor of 4 and material’s elasticity modulus, vertical beam’s elastic section modulus was calculated to be 59.2 cm3. Based on that HEB 140 beam was chosen, which had a elastic section modulus of 79 cm3. A controll-calculation for bucling was carried out and it showed that HEB 140 beam at 4.05 meter lenght has a maximum buckling load capacity of 118456 N, which is more than the 54700 N acting on the beam. To optimize the geometry of the model, the construction was drawn using HEB 120 beams, so that changes in natural oscillation frequency of the constrution and therefor rigidity would be more apparent. The natural oscillation frequency was found using ANSYS Workbench software, where different configurations of the model were calculated and the most rigid geometry was found. To avoid resonance, the natural oscillation frequency of the constrution needs to be different from the working frequency of the screen at 11.33 Hz. Allowed frequency range was determined to be 15.1...18.9 Hz and 8.1...9.1 Hz. The model with optimized geometry, using HEB 120 beams, had a natural oscillation frequency of 13.49 Hz, having replaced the vertical beams with HEB 140 beams, the natural oscillation frequency rose up to 14.9 Hz, which still wasn’t sufficient. To make the construction more rigid, vertical beams were replaced with HEB 160 beams, horizontal beams with HEB 140 beams and diagonal supports were made from HEB 120 beams and 80x80x6 mm square hollow sections. The natural oscillation frequency of the final model was 17.17 Hz. Having found the final geometry and beams the model was designed to completion. Beam assemblies were designed to be assembled using M16 bolts, joints between beams and end flanges were made more rigid using reinforcement ribs. To ensure the bolts are suitable a conctrol-calculation was conducted in the most unfavorable joint, the joint between the square hollow section diagonal support and the vertical beam, where a single bolt is working against shear forces. The shear capacity of 24120 N was calculated and a shear force of 703 N acting upon the bolt. Since the shear capacity is bigger than the acting force, the bolts are suitable. To connect the screen to the construction, a footing was designed where the screen legs will be bolted on to the construction using M12 bolts. To ensure that welded joints are strong enough to withstand forces acting upon them control calculations were made. Two joints were chosen for the calculation, weld between the vertical beam and the base plate and the weld between the square hollow section diagonal support and its end flange. It was determined that maximum allowable stress on the weld is 57.7 N/mm2. The maximum stress on the weld between the beam and the base plate was calculated to be 1.2 N/mm2 and in the weld between the diagonal support and end flange plate was calculated to be 0.5 N/mm2. So the designeded welds are suitable for their purpose. In the economical calculation, the design cost of the support sctructure was fount. A total of 158 hours were spent designing, calculations and drawing process of this structure. With an hourly cost of 30 euro, the cost came to 4740 euros.

Kirjeldus

Märksõnad

TTK Subject Categories::Mehaanika::Tugevusõpetus, TTK Subject Categories::Mehaanika::Teoreetiline mehaanika, TTK Subject Categories::Mehaanika::Tootearendus

Viide