Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 86 === This paper presents a new mold grinding methodology using
theabrasives jet grinding technique.The method is a cold
workingprocess that possesses some distinct features including
theremoval of abrasive cutting heat directly by mixing jet
flowand the enhancement of mold surface fatigue strength by
theeffect of particles impact on grindng surface.The abrasivejet
grinding technique utilezes the kinetics embeddedin thepressured
mixing jet and the generated material removal pursiveforces on
the mold surface to improve surface quality.The grinding
particles in the mixing jet impose relatively higher pressure on
the surface surrounding the peak andrelatively lower pressure
difference tends to remove unevenrough surface and thus enhance
the surface quality gradually.By adjusting the jet velocity,flow
pressure,and the inclinationangle of the jet,the quality of the
mold surface can be welloptimized and controlled.The proposed
method possessesmany advantages that are shared by other
grindingmethods.These include the independence of the
shapecomplexity of the mold surface,the wide range of
grindingzone,and the possibility of automation for the process.
The paper establishes analytical basis for both the simulationof
the jet grinding mechanics and the planning ofregenerative
trajectory in grinding kinematics.The bestworking range of key
grinding parameters and associatedflow dynamics are estimated
based on the analytical-numericalresults.A corresponding
abrasive jet grinding system,includingthe pressured mixing
subsystem,the jet propulsive system,thegrinding trajectory
generation platform and the CNC feed andspin control subsystem,
is thus designed and constructedaccordingly.The system is then
employed for grindingillustrations using two predesigned mold
surfaces.The results are measured,processed and presentedfor
various possible conditions including operationtime,particle
sizes,and other operationvariables.The resulting quality of the
moldsurface obtained directly from experimentalstudy agrees well
with that of analyticalsimulations.The proposed abrasive jet
grinding techniqueproposed in this paper shows great potential
and cao beused for precision grinding in various industries.
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