Polyurethane rwb thaiv tsev txheej yuav tsum muaj xws li ib tug niaj hnub ua npuas ncauj lub cev; Txawm li cas los xij, txiav qhib cov yeeb nkab qee zaum qhia pom qhov khoob hauv ib cheeb tsam -voids hauv cov npuas dej. Lub xub ntiag ntawm cov voids hnyav cuam tshuam kev ua haujlwm ntawm rwb thaiv tsev thiab ua rau muaj kev pheej hmoo ntawm kev ua tsis tiav ntxov ntxov.
Thawj qhov ua rau voids yog qhov tsis txaus ntawm cov khoom siv foaming. Cov yeeb nkab-hauv- cov txheej txheem tsim yeeb nkab yuav tsum tau txhaj cov kua polyurethane precursors rau hauv qhov chaw annular ntawm cov yeeb nkab steel thiab sab nrauv; yog tias qhov ntim ntim tsis txaus, cov npuas tsis tuaj yeem sau tag nrho qhov chaw. Qee cov tuam ntxhab txiav cov ces kaum ntawm cov nqi khoom siv los ntawm kev kwv yees qhov xav tau txhaj tshuaj, ua rau muaj qhov sib txawv hauv zos. Tsis zoo flowability ntawm polyurethane sib tov kuj tseem tuaj yeem tiv thaiv kev faib tawm txawm tias thaum txhaj tshuaj, ua rau tsis muaj qhov tsim.
Kev txhaj tshuaj tsis txaus yog lwm qhov ua rau cov voids. Polyurethane foaming yuav tsum tau txhaj tshuaj tshwj xeeb los xyuas kom meej cov ntaub ntawv raw khoom sib cais sib npaug rau txhua lub ces kaum ntawm qhov chaw annular. Yog tias qhov siab qis dhau lawm, cov khoom siv tsis tuaj yeem ncav cuag qhov chaw nyob deb, muaj peev xwm tsim cov voids ntawm qhov kawg. High- cov khoom siv ua npuas dej hauv cov chaw ua haujlwm feem ntau ua haujlwm ntawm kev txhaj tshuaj ntawm 10-20 MPa, kom ntseeg tau tias cov khoom siv tsis sib xws. Conversely, manufacturers siv rudimentary khoom feem ntau tsis txaus txhaj tshuaj, ua rau inconsistent cov khoom zoo.
Tsis txaus preheating ntawm cov yeeb nkab steel kuj yog ib qho tseem ceeb. Polyurethane foaming yog ib qho exothermic cov tshuaj tiv thaiv uas yuav tsum tau muaj qee yam ntawm cov cua sov los txhawb cov txheej txheem. Yog tias cov yeeb nkab steel kub qis dhau lawm, cov npuas dej sib cog lus sai sai thaum sib cuag nrog qhov chaw txias, thiab cov txheej txheem kho qeeb qeeb, ua rau kev tsim cov voids shrinkage. Qhov kev pheej hmoo ntawm voids yog qhov siab dua thaum foaming ua rau lub caij ntuj no yam tsis muaj preheating.
Voids tuaj yeem yooj yim tsim ntawm qhov interface qhov twg ob qhov sib cais foaming theem sib ntsib. Qhov zoo tshaj plaws, cov txheej txheem foaming koom nrog ib leeg, txuas ntxiv txhaj tshuaj yam tsis muaj kev cuam tshuam. Yog tias kev txhaj tshuaj raug cuam tshuam los ntawm cov khoom siv tsis ua haujlwm lossis kev ua haujlwm yuam kev, lub seam ntawm ob theem foaming yuav ua tsis tau zoo, tawm hauv qhov tsis muaj dab tsi. Thaum tsim tau, cov voids no yuav raug kuaj pom thaum lub Hoobkas tshuaj xyuas los yog plam los ntawm kev tsis pom. Kev yuav khoom los ntawm cov tuam txhab lag luam uas muaj peev xwm tshuaj xyuas tau zoo tuaj yeem pab txo qis kev pheej hmoo ntawm qhov tsis muaj dab tsi - cov khoom cuam tshuam txog qhov chaw ua haujlwm.