Istraživanje uticaja raspodele opterećenja eksploatacionih uslova na radnu sposobnost kardanovih spojnica

Abstract

Generalno posmatrano, svi mašinski sistemi se sastoje od pogonske i radne grupe, odnosno pogonske i radne mašine. Spoj ovih mašina se ostvaruje posebnim sklopovima, mašinskim elementima – spojnicama. Njihova osnovna funkcija je prenošenje opterećenja i kretanja sa pogonske na radnu mašinu. Poznato je da su spojevi najčešće najslabija karika u svakom mašinskom sistemu. Saglasno velikom skupu različitih radnih i pogonskih mašina, sa različitim radnim performansama, razvijen je veliki broj različitih spojnica. Međutim, kod transportnih sredstava i drugih mašina, uslovi rada nalažu različite međusobne položaje pogonske i radne mašine. Ime i pojam posebne vrsta spojnica vezano je za pionire u konstrukciji ovih spojnica, slavnog italijanskog naučnika Đerolama Kardana (Gerolamo Cardano, 1501-1576) i Roberta Huka (Robert Hooke, 1635-1703). Konstrukciona rešenja ovih spojnica prolazila su kroz različite faze razvoja. Dinamika razvoja konstrukcionih rešenja ovih spojnica prikazane je u posebnom Poglavlju 3 ove disertacije. Kardanove spojnice (kardanska vratila) su posebna vrsta mehanizama za prenošenje obrtnog momenta, odnosno snage, koji spajaju vratila čije se ose nalaze prostorno pod izvesnim stalnim ili u toku rada promenljivim uglom, dozvoljavajući, pri tome, u toku vremena relativno pomeranje. Ovo pomeranje može biti ugaono i translatorno. Glavni pokazatelji radne sposobnosti kardanovih spojnica je njihov radni vek i stepen pouzdanosti. Najveći uticaj na ove pokazatelje radne sposobnosti ima karakter raspodele linijskog opterećenja kod spregnutih delova Kardanove spojnice. U cilju rasvetljavanja fenomena raspodele linijskog opterećenja i sagledavanja stepena kompatibilnosti između geometrijskih karakteristika spregnutih delova i raspodela linijskih opterećenja, u disertaciji su formirani analintički i numerički modeli pod odgovarajućim predpostavkama.

general, all mechanical systems consist of drive and driven groups, or driving and driven machines. The connection of these machines is achieved by special joints, machine elements - couplings. It is known that these joints are often the weakest link in any mechanical system. Pursuant to a large set of different drive and driven machines with different operating performance, a large number of different coupling types were developed. However, а working conditions of transport vehicles and other machinery require different mutual positions of the driving and operating machinery. The name and concept of one type of couplings is related to the pioneers in the design of these joints, the famous Italian scientist Gerolamo Cardano (1501-1576) and Robert Hooke (1635-1703). The designs of these couplings are passed through various stages of development. The innovative designs development dynamics of these couplings are shown in a separate chapter 3 of this study. Cardan joints (cardan shafts) have a large range of applications in mechanical engineering because of the capability of transferring the load and motion from one shaft to another with different joint angle allowing, thereby, over time relative movement. This movement can be angular and translational. The main indicators of functional ability of cardan coupling are their service life and reliability. The greatest influence on these indicators of functional ability has the character of the linear load distribution on cardan joints rolling parts. In order to shed some more light to the phenomena of linear load distribution and correlation between the geometric characteristics of rolling elements and the distribution of the linear load, analytical and numerical models under appropriate assumptions are established in this study. The obtained results shows, that with the standard (the existing) geometry of rolling parts, the engagement of points in root of Cardan cross jurnal in the load transfer is negligible due to very uneven linear load distribution. This unfavorable distribution of the linear load can be reduced with an appropriate combination of geometrical parameters of cardan cross rolling parts. Greater improvement of linear load distribution, ordering the appropriate shape reconstruction of cardan cross rolling parts.