GE product design产品设计

DesignGEPlasticsGEEngineeringThermoplasticsDESIGNGUIDE•DesignforManufacture•RelativeMotionSituationsProductProductDesign4-2•ProductDesignProductdesignaccountsforasmallamountofdevelopmentcostsbutaffectsamajorityoftheproductcosts.Gainsinproductivityareavailabletothedesignerwhointelligentlyusesthermoplasticcomponentsanddesignsthemformanufactureandassembly.Also,situationsinvolvingplasticpartssubjecttorelativemotionincludinghinges,gears,bearingsorguidesshouldbeconsidered.Executingwell-conceivedproductdesignenhancestheprobabilityofsuccess.ContentsProductDesign•4-3DesignforManufacturing&Assembly.........................4-410BasicRules................................4-4BearingsandGuides.................4-8Wear.........................................4-8HeatDissipation...............................4-8DimensionalTolerance/Stability..................4-9SurfaceFinish/Molding.........................4-9WeldLineSeverity/Location.....................4-9Strength.....................................4-10Stiffness.....................................4-10Hinges............................4-11TypesofHinges..............................4-11LivingHinge/AssemblyHinge.................4-11PinandTubeHinges.........................4-12SnapTogetherHinge........................4-12InsertMoldedHinges.........................4-13SecondaryAssembled........................4-13RathbunHinges.............................4-13AssembledHinges..........................4-14DesignIssues......................4-14WeldLines...................................4-14PartingLines.................................4-14Moldability...................................4-15CoefficientofFriction..........................4-15Lubricants...................................4-15ThermalEffects...............................4-15CoefficientofThermalExpansion...............4-16Molded-InStress.............................4-16StressRelaxation.............................4-16YieldStrain..................................4-17Gears.............................4-18GearTerminology.............................4-19TypesofGears...............................4-21SpurGears.................................4-21HelicalGears...............................4-22AnnularorInternalGears....................4-22BevelGears................................4-23WormGears................................4-23GearToothForms...........................4-24GearActionandForce........................4-24GearStress..................................4-26TangentialLoadonaGearTooth................4-27GearTorque..................................4-27FactorsAffectingToothLoading................4-28HelicalGearDesign...........................4-29BevelGearDesign............................4-30WormGearDesign............................4-30Backlash....................................4-31FilletRadius..................................4-33TipRelief....................................4-34Noise.......................................4-34ProductDesign4-4•ProductDesignDesignForManufacturing&AssemblyIntoday’smanufacturingcycle,achievingincreasedproductivitygainsrequiresnewanddifferentapproachesthanthoseusedinthepast.Theseapproachescannolongerbesimpleone-for-onematerialreplacements;rather,considerationshouldbegiventotheuseofengineeringthermoplasticsforboththeconsolidationofpartsintomorefunctionalapplicationsandtheassemblyofthesepartsduringmanufacture.Byconsideringmanufacturingandassemblystepsintheinitialdesignequation,manufacturershavetheopportunitytoengineerboththepartandtheproduc-tionprocessatthesametime.Thisapproachallowsdesignengineerstomaximizetheuseofengineeringthermoplastics.Morefunctionaldesignscanmeanfewerparts.Attachmentmethodssuchassnap-fits,integratedslides,screwthreadsandbossescanbeincorporatedwithextremelyclosetolerances.Throughthiskindofpartsconsoli-dation,inventoryandassemblytimearereduced,asistheentireproductdevelopmentcycle.Withinthemanufacturingprocessthereisalsotheopportunityforgreaterautomationandreducedenergyconsumptionduringthemanufacturingprocess.Thetenbasicrulesofdesignonthefollowingpagescanassistdesignersinobtainingpositiveresultswhenutilizingengineeringthermoplastics.10BasicRulesRule1–MinimizethenumberofpartsHavingfewerpartsisbeneficialtothemanufacturerfromanumberofstandpoints.Itreducesoverheadbyeliminatingdocumentation,(drawings,materialspecifications,purchaseorders,inspectionreports,routingandinventory),speedsassemblyandimprovesquality.Todeterminethetheoreticalminimumnumberofpartsrequiredinanassembly,theneedforeachpartshouldbeProductivityGainsMultifunctionalpartsreducenumberofparts,andeaseassemblyandhandling.DesignForManufacturing&AssemblyProductDesign•4-5challenged.Apartcanbeidentifiedasacandidateforeliminationifallthreequestionsarefoundtobenegative.•Doesthepartmoverelativetothematingpart?•Doesthefunctionrequireadifferentmaterial?•Isthepartrequiredfordisassemblyorservice?Figure4-1.Partsconsolidation.Typicalpartstobeeliminated:–Fasteners–Spacers–LabelsTobereplacedwith:SnapfitsultrasonicPressfitsthermalstake