现代数控机床原理与结构PPT资料.ppt

1、书名：#现代数控机床原理与结构（双语）ISBN：#978-7-111-42403-1作者：#郁元正出版社：#机械工业出版社本书配有电子课件现代数控机床原理与结构（双语）ppt 课件Chapter 2Motions&#coordinate system of Machine tools2.1 Motions of machine tool 2.2 Machine tool drive 2.3 Coordinate systems 现代数控机床原理与结构（双语）ppt 课件2.1 Motions of machine tool2.1.1 Purpose of motionsThe purpose

2、of machine tool motions is to remove materials from workpieces to obtain required shapes,dimensions and surface quality.Motion essentials are tool motions,workpiece motions,and cutting motions.2.1.2 Surface forming motionSurface forming motion is the relative cutting motion between tool and workpiec

3、e.Types and quantity of surface forming motion determine shape of workpiece,machining method and tool constructions现代数控机床原理与结构（双语）ppt 课件Outer circular surface turningSurface forming motion consists of:#Primary motionFeeding motion现代数控机床原理与结构（双语）ppt 课件1）Primary motionPrimary motion causes relative mo

4、tion between cutting tool and workpiece,and remove material from workpiece.Examples of primary motions:#Rotary motion of workpiece（turning）Rotary motion of cutting tools（drilling,milling,boring）Reciprocating motion of cutting tools（broaching,planing）Every machining process must have,and only has a p

5、rimary motion.现代数控机床原理与结构（双语）ppt 课件2）Feeding motionFeeding motion causes an secondary relative motion between cutting tool and workpiece,and enables tool can continuously remove material from workpiece to form a desired shape.Examples of feeding motionAxial and radial motions of cutting tool（turning

6、）Step motions of cutting tool or workpiece（planing）Note:#Feeding motion can be performed by both cutting tools or workpieces;#Two or more feeding motions can co-exist（gear hobbing）;#Zero feeding motion is possible（broaching）.现代数控机床原理与结构（双语）ppt 课件Thinking Identify primary motions and feeding motions.

7、PlaningBroachingMilling现代数控机床原理与结构（双语）ppt 课件2.1.3 Assistant motionsAll motions other than surface forming motions,including plunge motion,indexing motion,alignment motion,fast moving,and other actions.1）Plunge motion Plunge cutting tool into workpiece to obtain a certain dimension2）Indexing motion P

8、eriodical moving,rotating of worktable or tool post to machining each surfaces of workpiece,e.g.multi-thread screws turning,polygon machining,etc.现代数控机床原理与结构（双语）ppt 课件3）Alignment motionIt is used to obtain correct relative positions between cutting tool and workpiece,e.g.aligning drill to hole cente

9、r by moving rocker arm of the driller.4）Fast moving and other actionsFast moving improves machining efficiency.Other actions include direction change,clamping,releasing,etc.现代数控机床原理与结构（双语）ppt 课件2.2Machine tool driveTo realize those necessary motions for machining,each NC machine tool should have thr

10、ee basic units:#（1）Actuators,e.g.spindle,tool post,worktable,etc.They direct perform machining（2）Drive system,e.g.AC/DC motors,step motors,etc.They produce mechanical motion for actuators.（3）Transmissions.They transfer motion and power from drive system to actuators.Transmissions can be in mechanica

11、l,electric,hydraulic and pneumatic现代数控机床原理与结构（双语）ppt 课件2.2.1 Transmission connectionConnection between actuator and power or between actuators by transmission components.Transmission diagram of CA6140 horizontal lathe2.2.2 Transmission chain A series of transmission components that consist a transmi

12、ssion connection is known as transmission chain.Two forms of transmission（1）Constant ratio and direction.（2）Variable and direction.Gears,worm gears-shaft,ball screw-nutAdjusting gears,clash gears,clutch gear shiftTransmission chains include external and internal relations:#1）External relationConnect

13、ing power unit and actuatorsDriving actuators running at designed speedDetermining machining efficiency and surface roughness rather than shape of workpiece.2）Internal relationConnecting and regulating motions between actuators;#Precise transmission ratio is important.Frictional transmission（e.g.clu

14、tch）or instantaneous variable ratio（chain drive）is unacceptable;#Screw turning requires stringent transmission ratio between spindle rotation and tool post moving to ensure precise thread pitch.2.2.3 Transmission diagramTransmission diagram briefly represents relative motion paths of surface forming

15、.Symbols for transmission diagramCutting toolSpindleMotorCombined unitConstant ratioHob（滚刀）Variable ratioTransmission diagram of screw turningGear ratio1（external relation）Gear ratio2（internal relation）MotorThread Cutting toolLead screwSpindleFrom NC machine tools,spindle and tool post may be driven

16、 by their own motors.2.2.4 Transmission system diagram:#XKA5750 milling machineCartesian coordinate（Right hand rules）Descartes（1596-1690）French philosopher,mathematician2.3.1 Standard coordinate system and direction1.ISO coordinate system2.3 Coordinate system for NC machine tools2.Directions of axes（1）All axes assume that tools move while worktables rest;#When worktable moves,it moves along an axis marked with“;#Notes:#Worktable motion only be considered during machine tool design stage.（2）Positive direction-The