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时间:2020-03-08
《模具专业英语 教学课件 作者 王浩钢 14456第4章.ppt》由会员上传分享,免费在线阅读,更多相关内容在应用文档-天天文库。
1、Lesson4FeedSystemItisnecessarytoprovideaflow-wayintheinjectionmouldtoconnectthenozzle(oftheinjectionmachine)toeachimpression.Thisflow-wayistermedthefeedsystem.Normallythefeedsystemcomprisesasprue,runnerandgate.Thesetermsapplyequallytotheflow-wayitself,andtothemoldedma
2、terialwhichisremovedfromtheflow-wayitselfintheprocessofextractingthemolding.Atypicalfeedsystemforafour-impression,twoplate-typemouldisshowninFigure4.1.Itisseenthatthematerialpassesthroughthesprue,mainrunner,branchrunnersandgatebeforeenteringtheimpression.Asthetemperat
3、ureofmoltenplasticisloweredwhilegoingthroughthesprueandrunner,theviscositywillrise;therefore,theviscosityisloweredbyshearheatgeneratedwhengoingthroughthegatetofillthecavity①.Itisdesirabletokeepthedistancethatthematerialhastotraveldowntoaminimumtoreducepressureandheatl
4、osses.Itisforthisreasonthatcarefulconsiderationmustbegiventotheimpressionlayoutandgate’sdesign.(a)Figure4-1Feedsystem:(a)typicalshotofconsistingofmoldingswithsprue,runnerandgatesattached;(b)sectionthroughfeedportionofmouldSprueAsprueisachannelthroughwhichtotransfermo
5、ltenplasticinjectedfromthenozzleoftheinjectorintothemold.Itisapartofspruebush,whichisaseparatepartfromthemold.RunnerArunnerisachannelthatguidesmoltenplasticintothecavityofamold.GateAgateisanentrancethroughwhichmoltenplasticentersthecavity.Thegatehasthefollowingfunctio
6、ns:restrictstheflowandthedirectionofmoltenplastic;simplifiescuttingofarunnerandmoldingstosimplifyfinishingofparts;quicklycoolsandsolidifiestoavoidbackflowaftermoltenplastichasfilledupinthecavity.ColdslugwellThepurposeofthecoldslugwell,shownoppositethesprue,istheoretic
7、allytoreceivethematerialthathaschilledatthefrontofthenozzleduringthecoolingandejectionphase②.Perhapsofgreaterimportanceisthefactthatitprovidespositivemeanswherebythespruecanbepulledfromthespruebushforejectionpurposes.Thesprue,therunner,andthegatewillbediscardedafterap
8、artiscomplete.However,therunnerandthegateareimportantitemsthataffectthequalityorthecostofparts.Notes①Asthetemperatureofmolte
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