模具专业英语 教学课件 作者 王浩钢 14456第5章.ppt

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1、Lesson5SprueBushandRegisterRingThespruebushisdefinedasthatpartifthemouldinwhichthesprueisformed.Inpracticethespruebushistheconnectingmemberbetweenthemachinenozzleandthemouldface,andprovidessuitableaperturethroughwhichthematerialcantravelonitswaytotheimpressionsortothestartoftheru

2、nnersysteminmulti-impressionmoulds.Thespruebushisfairlyhighlystressedinsomeapplicationsandshouldthereforebemadefromanickelchromesteelandshouldalwaysbehardened.Notethatwhileinitiallythenozzlemayhavebeensetupcorrectly,anincreaseintheinjectioncylindertemperaturewillcauseafairlyhighf

3、orcetobeappliedtothespruebushbecauseoftheexpansionoftheinjectioncylinder①.Theinternalapertureofthespruebushhasbetween2°and4°includedtaper,whichfacilitatesremovalofthespruefromthemouldattheendofmoldingcycle.Forreference,2;2.6;3and4aretheincludedtapersadoptedbyvariousstandardpartss

4、uppliers.Therearetwobasicdesignsofspruebushwhichdifferonlywithrespecttotheformofseatingbetweenthespruebushandnozzleofthemachine.Bothdesignareshown(Figure5-1(a)(c)).Thefirstoftheseisaspruebushwithasphericalrecesswhichisusedinconjunctionwithasphericalfrontendednozzleasillustrated(F

5、igure5-1(a)).Thesecondhasaperfectlyflatrearface,theseatingbetweenitanditscorrespondingnozzlebeingshown(Figure5-1(c)).Figure5-1Sprueandnozzle(a)spherical;(c)flat;(b)(d)illustratingeffectofmisalignmentbetweenspruebushandnozzleProvidingthealignmentbetweenthenozzleandthebushaperture

6、sisperfect,aleak-freejointisachievedwiththesphericalseating.Itshouldbenotedthattheradiusonthenozzleisslightlylessthanthatinthebush,whichensuresbothpartsareinphysicalcontactattheapertures.However,ifthenozzleandspruebushareslightlyoutofline(dueperhapstowearonplatenbushes)agapwillre

7、sultandleakagebehindthemouldwilldevelop(Figure5-1(b)).Thisdrawbackisnotpresentifslightmisalignmentoccursattheseatingofthespruebushandflat-facednozzle(Figure5-1(d)).Ascanbeseen,noleakagecanoccurifthetwoaperturesareslightlyoutofthelineandnorestrictiontoflowwilloccureither,providing

8、thatthespruebushhasanapertureslightlylar