先進(jìn)制造技術(shù)--施平五單元(編輯修改稿)
2025-03-10 00:31 本頁(yè)面
【文章內(nèi)容簡(jiǎn)介】 VD, physical vapor deposition – a variety of vacuum deposition and is a general term used to describe any of a variety of methods to deposit thin films by the condensation of a vaporized form of the material onto various surfaces .The coating method involves purely physical processes such as high temperature vacuum evaporation or plasma sputter bombardment rather than involving a chemical reaction at the surface to be coated as in chemical vapor deposition Modern manufacturing technologies coated tools puter simulation of the basic physical process underlying physical vapour deposition: a single Cu atom deposited on a Cu surface 14 5. Modern manufacturing technologies ? Lubricating coating material – A coating to enhance lubrication in cutting (especially in dry cutting) – Coating material ? MoS2 (molybdenum disulfide) ? Multilayer coating – To get a bined property of the cutting tool – CVD+PVD – TiN+ MoS2 – … ? Diamondcoated tool – Diamond: super hard, ideal material for machining abrasive, nonferrous metals and nonmetallic posites Modern manufacturing technologies coated tools 15 5. Modern manufacturing technologies ? Factors lead to tool failures – Extreme heat (cutting edge temperature exceeds 1000℃ ) ? Degrades binders and other tool constituents ? Triggers detrimental chemical reactions between tool and workpiece – High pressure – Abrasion – Shock ? thermal shock ? mechanical shock ? Basic failure mechanisms – Crater wear – Thermal deformation and cracking – Nose wear – Builtup edge – Fracture – Flank wear Modern manufacturing technologies failure mechanism of cutting tools 16 5. Modern manufacturing technologies ? High speed machine – High spindle speed and feed speed – Spindle speed exceeds 10,000 rpm ? Benefit of HSM – Improved performance and product quality (such as finer finish) – Reduced production time, lower cost ? Factors hinders high speed – Weight of mobile ponent ? Overshoot, tipup of machine – Center of gravity ? Lower center of gravity can reduce problem like tipup of machine – Rigidity, stability ? Key to HSM – Axis drive ? Linear motor is more rigid than ballscrew, gearbox, etc. – Accuracy – Machine configuration – Machine programming, training and maintenance Modern manufacturing technologies high speed machining 17 5. Modern manufacturing technologies ? Hardness of material – Defined by its resistance to permanent deformation – It’ s the bination of elastic and plastic property that determine a material’ s resistance to permanent deformation – 555HRC~65HRC – Tensile strength up to 2400MPa ? Hard turning – Small depth of cut and feed though, much
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