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About the deceleration principle of double screw extruder

About the deceleration principle of double screw extruder

  • Categories:Industry News
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  • Time of issue:2020-07-17 16:40
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(Summary description)Inmostextruders,thescrewspeedischangedbyadjustingthemotorspeed.Thedrivemotorusuallyrotatesatafullspeedofabout1750rpm,whichistoofastforanextruderscrew.Ifitisrotatedatsuchafastspeed,toomuchfrictionalheatwillbegenerated,andtheresidencetimeoftheplasticwillbetooshorttoprepareauniformandwell-stirredmelt.Thetypicalreductionratioshouldbebetween10:1and20:1.Bothgearsandpulleyblockscanbeusedinthefirststage,butgearsarebestusedinthesecondstageandthescrewispositionedatthecenterofthelastbiggear.Forsomeslow-runningmachines(suchasthetwin-screwusedforUPVC),theremaybethreedecelerationstages,andthemaximumspeedmaybeaslowas30rpmorless(aratioof60:1).Ontheotherhand,someverylongtwinscrewsusedformixingcanrunat600rpmorfaster,soaverylowdecelerationrateandmoredeepcoolingarerequired.