故障的分析、尺寸的决定以及凸轮的分析和应用--中英文翻译

3.0 闻远设计 2023-08-11 58 4 87.5KB 16 页 20光币
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故障的分析、尺寸的决定以及凸轮的分析和应用
Failure AnalysisDimensional Determination And
AnalysisApplications Of Cams
AbstractIt is absolutely essential that a design engineer know how and why parts fail so
that reliable machines that require minimum maintenance can be designedCams are among
the most versatile mechanisms availableA cam is a simple two-member deviceThe input
member is the cam itselfwhile the output member is called the followerThrough the use
of camsa simple input motion can be modified into almost any conceivable output motion
that is desired
Key words: failure high-speed cams design properties
INTRODUCTION
It is absolutely essential that a design engineer know how and why parts fail so that
reliable machines that require minimum maintenance can be designedSometimes a failure
can be serioussuch as when a tire blows out on an automobile traveling at high speedOn
the other handa failure may be no more than a nuisanceAn example is the loosening of
the radiator hose in an automobile cooling systemThe consequence of this latter failure is
usually the loss of some radiator coolanta condition that is readily detected and corrected
The type of load a part absorbs is just as significant as the magnitudeGenerally
speakingdynamic loads with direction reversals cause greater difficulty than static
loadsand thereforefatigue strength must be consideredAnother concern is whether the
material is ductile or brittleFor examplebrittle materials are considered to be
unacceptable where fatigue is involved
Many people mistakingly interpret the word failure to mean the actual breakage of a
partHowevera design engineer must consider a broader understanding of what
appreciable deformation occursA ductile materialhowever will deform a large amount
prior to ruptureExcessive deformationwithout fracturemay cause a machine to fail
because the deformed part interferes with a moving second partThereforea part fails(even
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if it has not physically broken)whenever it no longer fulfills its required functionSometimes
failure may be due to abnormal friction or vibration between two mating partsFailure also
may be due to a phenomenon called creepwhich is the plastic flow of a material under load
at elevated temperaturesIn additionthe actual shape of a part may be responsible for
failureFor examplestress concentrations due to sudden changes in contour must be taken
into accountEvaluation of stress considerations is especially important when there are
dynamic loads with direction reversals and the material is not very ductile
In generalthe design engineer must consider all possible modes of failurewhich
include the following
——Stress
——Deformation
——Wear
——Corrosion
——Vibration
——Environmental damage
——Loosening of fastening devices
The part sizes and shapes selected also must take into account many dimensional factors
that produce external load effectssuch as geometric discontinuitiesresidual stresses due to
forming of desired contoursand the application of interference fit joints
Cams are among the most versatile mechanisms availableA cam is a simple two-
member deviceThe input member is the cam itselfwhile the output member is called the
followerThrough the use of camsa simple input motion can be modified into almost any
conceivable output motion that is desiredSome of the common applications of cams are
——Camshaft and distributor shaft of automotive engine
——Production machine tools
——Automatic record players
——Printing machines
——Automatic washing machines
——Automatic dishwashers
The contour of high-speed cams (cam speed in excess of 1000 rpm) must be determined
mathematicallyHoweverthe vast majority of cams operate at low speeds(less than 500
rpm) or medium-speed cams can be determined graphically using a large-scale layoutIn
generalthe greater the cam speed and output loadthe greater must be the precision with
which the cam contour is machined
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摘要:

外文翻译故障的分析、尺寸的决定以及凸轮的分析和应用FailureAnalysis,DimensionalDeterminationAndAnalysis,ApplicationsOfCamsAbstract:Itisabsolutelyessentialthatadesignengineerknowhowandwhypartsfailsothatreliablemachinesthatrequireminimummaintenancecanbedesigned;Camsareamongthemostversatilemechanismsavailable.Acamisasimpletwo-me...

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作者:闻远设计 分类:课程设计课件资料 价格:20光币 属性:16 页 大小:87.5KB 格式:DOC 时间:2023-08-11

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