mechatronic elements

8/16/2019 Mechatronic Elements

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MECHATRONIC ELEMENTS

• MACHINE STRUCTURE:

• machine structure is themajor supporting and loadcarrying member of themachine tool.the machinestructure is subjected to

static and dynamic forces. itis essential that the structuredoes not deform or vibratebeyond the allowable limitsunder action of these forces.

• REQUIRMEN! "# M$%&INE!RU%URE'

• rigid frame• high sti(ness to weight ratio• good damping characteristics• thermal stability


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GUIDEWAYS• he basic function of guideways are'

• control the direction or line of action of the carriage or the table on which tool

or wor) piece is placed

• absorb all static and dynamic forces

• ie the guideway ensures that the machine tool operative element carrying thewor) piece or cutting tool moves along predetermined path* which is generallya straight line and in some cases circular

the major re+uirements that the guideway must satisfy are'

• high accuracy ,nish of guideway surfaces

• high accuracy of travel

• ade+uate load carrying capacity

• low wear and tear

• high rigidity

• good damping properties

• durability

• conventional guides* operating under conditions of sliding friction do not haveconstant friction. he coe-cient of friction varies with the sliding velocity


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Machine Tool Guideways


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CNC Guideways


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STICK SLIP PHENOMENON

• conventional guides operating underconditions of sliding friction do not haveconstant friction.

• coe-cient of friction is very high when themovement commences and as speed of slideincreases* it rapidly falls and beyond acertain critical velocity remains almost

constant. therefore to start the movementthe force to overcome friction has to be high.

• hen the force is applied the energy storedin drive mechanism along with applied forcecauses carriage to slip and move at fasterrate.

• $s speed increases friction decreases and a

greater amount of travel than intended forslide ta)es place.

• his cycle of events repeat itself resulting inerrors of positioning and conse+uently jer)ymotion. his is called stic) slip phenomenon.


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$NI #RI%I"N /UI0E$1!

mechatronic elements

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