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
外 文 翻 译
故障的分析、尺寸的决定以及凸轮的分析和应用
Failure Analysis，Dimensional Determination And
Analysis，Applications Of Cams
Abstract：It is absolutely essential that a design engineer know how and why parts fail so
that reliable machines that require minimum maintenance can be designed；Cams are among
the most versatile mechanisms available．A cam is a simple two-member device．The input
member is the cam itself，while the output member is called the follower．Through the use
of cams，a 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 designed．Sometimes a failure
can be serious，such as when a tire blows out on an automobile traveling at high speed．On
the other hand，a failure may be no more than a nuisance．An example is the loosening of
the radiator hose in an automobile cooling system．The consequence of this latter failure is
usually the loss of some radiator coolant，a condition that is readily detected and corrected．
The type of load a part absorbs is just as significant as the magnitude．Generally
speaking，dynamic loads with direction reversals cause greater difficulty than static
loads，and therefore，fatigue strength must be considered．Another concern is whether the
material is ductile or brittle．For example，brittle materials are considered to be
unacceptable where fatigue is involved．
Many people mistakingly interpret the word failure to mean the actual breakage of a
part．However，a design engineer must consider a broader understanding of what
appreciable deformation occurs．A ductile material，however will deform a large amount
prior to rupture．Excessive deformation，without fracture，may cause a machine to fail
because the deformed part interferes with a moving second part．Therefore，a part fails(even
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if it has not physically broken)whenever it no longer fulfills its required function．Sometimes
failure may be due to abnormal friction or vibration between two mating parts．Failure also
may be due to a phenomenon called creep，which is the plastic flow of a material under load
at elevated temperatures．In addition，the actual shape of a part may be responsible for
failure．For example，stress concentrations due to sudden changes in contour must be taken
into account．Evaluation of stress considerations is especially important when there are
dynamic loads with direction reversals and the material is not very ductile．
In general，the design engineer must consider all possible modes of failure，which
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 effects，such as geometric discontinuities，residual stresses due to
forming of desired contours，and the application of interference fit joints．
Cams are among the most versatile mechanisms available．A cam is a simple two-
member device．The input member is the cam itself，while the output member is called the
follower．Through the use of cams，a simple input motion can be modified into almost any
conceivable output motion that is desired．Some 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
mathematically．However，the vast majority of cams operate at low speeds(less than 500
rpm) or medium-speed cams can be determined graphically using a large-scale layout．In
general，the greater the cam speed and output load，the greater must be the precision with
which the cam contour is machined．
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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...
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
