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word 文档 可自由复制编辑 附件 2：外文原文 Fundamental Geometrical Principles 1.1 Description of workpiece points 1.1.1 Workpiece coordinate systems In order for the machine or control to operate with the specified positions,these data must be entered in a reference system that corresponds to the direction of motion of the axis slides.A coordinate system with the axes X,Y and Z is used for this purpose.DIN 66217 stipulates that machine tools must use right-handed,rectangular(Cartesian)coordinate systems.The workpiece zero(W)is the origin of the workpiece coordinate system.Sometimes it is advisable or even necessary to work with negative positional data.Positions to the left of the origin are prefixed by a negative sign().1.1.2 Definition of workpiece positions To specify a position,imagine that a ruler is placed along the coordinate axes.You can now describe every point in the coordinate system by specifying the direction(X,Y and Z)and three numerical values.The workpiece zero always has the coordinates X0,Y0,and Z0.The infeed depth must also be described in milling operations.One plane is sufficient to describe the contour on a lathe.1.1.3 Polar coordinates The method used to date to specify points in the coordinate system is known word 文档 可自由复制编辑 as the Cartesian coordinate method.However,there is another way to specify coordinates,i.e.,as so-called polar coordinates.The polar coordinate method is useful only if a workpiece or part of a workpiece has radius and angle measurements.The point,on which the measurements are based,is called the pole.1.1.4 Absolute dimensions With absolute dimensions,all the positional data refer to the currently valid zero point.Applied to tool movement this means:the position,to which the tool is to travel.1.1.5 Incremental dimension Production drawings are frequently encountered,however,where the dimensions refer not to the origin,but to another point on the workpiece.In order to avoid having to convert such dimensions,it is possible to specify them in incremental dimensions.Incremental dimensions refer to the positional data for the previous point.Applied to tool movement this means:The incremental dimensions describe the distance the tool is to travel.1.1.6 Plane designations When programming,it is necessary to specify the working plane so that the control system can calculate the tool offset values correctly.The plane is also relevant to certain types of circular programming and polar coordinates.word 文档 可自由复制编辑 The third coordinate axis is perpendicular to this plane and determines the infeed direction of the tool(e.g.,for 2D machining).A plane is defined by means of two coordinate axes.The working planes are specified as follows in the NC program with G17,G18 and G19:Level Designation Infeed direction X/Y G17 Z Z/X G18 Y Y/Z G19 X 1.2 Position of zero points The various origins(zero points)and reference positions are defined on the NC machine.They are reference points for the machine to approach and for programming the workpiece dimensions.The diagrams show the zero points and reference points for drilling/milling machines and turning machines.Reference points They are:M Machine zero word 文档 可自由复制编辑 A Blocking point.Can coincide with the workpiece zero point(only turning machines).W Workpiece zero=Program zero B Start point.Can be defined for each program.Start point of the first tool for machining.R Reference point.Position determined by cams and measuring system.The distance to the machine zero M must be known,so that the axis position can be set at this place exactly on this value 1.3 Position of coordinate systems 1.3.1 Overview of various coordinate systems We distinguish between the following coordinate systems:The machine coordinate system with the machine zero M The basic coordinate system(this can also be the workpiece coordinate system W)The workpiece coordinate system with the workpiece zero W The current workpiece coordinate system with the current offset workpiece zero Wa In cases where different machine coordinate systems are in use(e.g.,5-axis transformation),an internal transformation function mirrors the machine kinematics on the coordinate system currently selected for programming.1.3.2 Machine coordinate system The machine coordinate system comprises all the physically existing word 文档 可自由复制编辑 machine axes.Reference points and tool and pallet changing points(fixed machine points)are defined in the machine coordinate system.Where the machine coordinate system is used for programming(this is possible with some of the G functions),the physical axes of the machine are addressed directly.No allowance is made for workpiece clamping.Right-hand rule The orientation of the coordinate system relative to the machine depends on the machine type.The axis directions follow the so-called three-finger rule of the right hand(in accordance with DIN 66217).Seen from in front of the machine,the middle finger of the right hand points in the opposite direction to the infeed of the main spindle.Therefore:the thumb points in the+X direction the index finger points in the+Y direction the middle finger points in the+Z direction 1.3.3 Basic coordinate system The basic coordinate system is a Cartesian coordinate system,which is mirrored by kinematic transformation(for example,5-axis transformation or word 文档 可自由复制编辑 by using Transmit with peripheral surfaces)onto the machine coordinate system.If there is no kinematic transformation,the basic coordinate system differs from the machine coordinate system only in terms of the axis designations.The activation of a transformation can produce deviations in the parallel orientation of the axes.The coordinate system does not have to be at a right angle.Zero offsets,scaling,etc.,are always executed in the basic coordinate system.The coordinates also refer to the basic coordinate system when specifying the working field limitation.1.3.4 Workpiece coordinate system The geometry of a workpiece is described in the workpiece coordinate system.In other words,the data in the NC program refer to the workpiece coordinate system.The workpiece coordinate system is always a Cartesian coordinate system and assigned to a specific workpiece.1.3.5 Frame system The frame is a self-contained arithmetic rule that transforms one Cartesian word 文档 可自由复制编辑 coordinate system into another Cartesian coordinate system.It is a spatial description of the workpiece coordinate system The following components are available within a frame:Zero offset Rotate Mirroring Scaling These components can be used individually or in any combination.Mirroring of the Z axis Shifting and turning the workpiece coordinate system One way of machining inclined contours is to use appropriate fixtures to align the workpiece parallel to the machine axes.Another way is to generate a coordinate system,which is oriented to the workpiece.The coordinate system can be moved and/or rotated with programmable frames.This enables you to move the zero point to any position on the workpiece align the coordinate axes parallel to the desired working plane by rotation and thus machine surfaces clamped in inclined positions,produce drill holes at different word 文档 可自由复制编辑 angles.Perf orming multi-side machining operations.The conventions for the working plane and the tool offsets must be observed in accordance with the machine kinematics for machining operations in inclined working planes.1.3.6 Assignment of workpiece coordinate system to machine axes The location of the workpiece coordinate system in relation to the basic coordinate system(or machine coordinate system)is determined by settable frames.The settable frames are activated in the NC program by means of commands such as G54.1.3.7 Current workpiece coordinate system Sometimes it is advisable or necessary to reposition and to rotate,mirror and/or scale the originally selected workpiece coordinate system within a program.The programmable frames can be used to reposition(rotate,mirror and/or scale)the current zero point at a suitable point in the workpiece coordinate system.You will thus obtain the current workpiece coordinate system.Several zero offsets are possible in the same program.1.4 Axes A distinction is made between the following types of axes when programming:word 文档 可自由复制编辑 Machine axes Channel axes Geometry axes Special axes Path axes Synchronized axes Positioning axes Command axes(motion-synchronous actions)PLC axes Link axes Lead link axes Behavior of programmed axis types Geometry,synchronized and positioning axes are programmed.Path axes traverse with feedrate F in accordance with the programmed travel commands.Synchronized axes traverse synchronousl y to path axes and take the same time to traverse as all path axes.Positioning axes traverse asynchronously to all other axes.These traversing movements take place independently of path and synchronized movements.Command axes traverse asynchrono usly to all other axes.These traversing movements take place independently of path and synchronized word 文档 可自由复制编辑 movements.PLC axes are controlled by the PLC and can traverse asynchronously to all other axes.The traversing movements take place independently of path and synchronized movements.1.4.1 Main axes/Geometry axes The main axes define a right-angled,right-handed coordinate system.Tool movements are programmed in this coordinate system.In NC technology,the main axes are called geometry axes.This term is also used in this Programming Guide.The Switchable geometry axes function(see Advanced)can be used to alter the geometry axes grouping configured by machine data.Here any geometry axis can be replaced by a channel axis defined as a synchronous special axis.Axis identifier For turning machines:Geometry axes X and Z are used,and sometimes Y.For milling machines:Geometry axes X,Y and Z are used.A maximum of three geometry axes are used for programming frames and the workpiece geometry(contour).The identifiers for geometry and channel axes may be the same,provided a reference is possible.word 文档 可自由复制编辑 Geometry axis and channel axis names can be the same in any channel so that the same programs can be executed.1.4.2 Special axes In contrast to the geometry axes,no geometrical relationship is defined between the specia axes.Axis identifier In a turning machine with revolver magazine,for example,Turret position U,tailstock V 1.4.3 Main spindle,master spindle The machine kinematics determine,which spindle is the main spindle.This spindle is declared the master spindle in the machine data.As a rule,the main spindle is declared the master spindle.This assignment can be changed with the program command SETMS(spindle number).Spindle identifier Identifiers:S or S0 1.4.4 Machine axes Machine axes are the axes physically existing on a machine.The movements of axes can still be assigned by transformations(TRANSMIT,TRACYL,or TRAORI)to the machine axes.If transformations are intended for the machine,different axis names must be determined.The machine axis names are programmed only in special cases,such as reference point or fixed point approaching.word 文档 可自由复制编辑 Axis identifier The axis identifiers can be set in the machine data.Standard identifiers:X1,Y1,Z1,A1,B1,C1,U1,V1 There are also standard axis identifiers that can always be used:AX1,AX2,.,Axn 1.4.5 Channel axes Channel axes are all axes,which traverse in a channel.Axis identifier Identifiers:X,Y,Z,A,B,C,U,V 1.4.6 Path axes Path axes define the path and therefore the movement of the tool in space.The programmed feed is active for this path.The axes involved in this path reach their position at the same time.As a rule,these are the geometry axes.However,default settings define,which axes are the path axes,and therefore determine the velocity.Path axes can be specified in the NC program with FGROUP 1.4.7 Positioning axes Positioning axes are interpolated separately,i.e.,each positioning axis has its own axis interpolator and its own feedrate.Positioning axes do not word 文档 可自由复制编辑 interpolate with the path axes.Positioning axes are traversed by the NC program or the PLC.If an axis is to be traversed simultaneously by the NC program and the PLC,an error message appears.Typical positioning axes are:Loaders for moving workpieces to machine Loaders for moving workpieces away from machine Tool magazine/turret A distinction is made between positioning axes with synchronization at the block end or over several blocks.POS axes:Block change occurs at the end of the block when all the path and positioning axes programmed in this block have reached their programmed end point.POSA axes:The movement of these positioning axes can extend over several blocks.POSP axes:The movement of these positioning axes for approaching the end position takes place in sections.Note Positioning axes become synchronized axes if they are traversed without the special POS/POSA identifier.word 文档 可自由复制编辑 Continuous-path mode(G64)for path axes is only possible if the positioning axes(POS)reach their final position before the path axes.Path axes that are programmed with POS/POSA are removed from the path axis grouping for the duration of this block.1.4.8 Synchronized axes Synchronized axes traverse synchronously to the path from the start position to the programmed end position.The feedrate programmed in F applies to all the path axes programmed in the block,but does not apply to synchronized axes.Synchronized axes take the same time as the path axes to traverse.A synchronized axis can be a rotary axis,which is traversed synchronously to the path interpolation.1.4.9 Command axes Command axes are started from synchronized actions in response to an event(command).They can be positioned,started,and stopped fully asynchronous to the parts program.An axis cannot be moved from the parts program and from synchronized actions simultaneously.Command axes are interpolated separately,i.e.,each command axis has its own axis interpolator and its own feedrate.1.4.10 PLC axes PLC axes are traversed by the PLC via special function blocks in the basic program;their movements can be asynchronous to all other axes.The word 文档 可自由复制编辑 traversing movements take place independently of path and synchronized movements.1.4.11 Link axes Link axes are axes,which are physically connected to another NCU and whose position is controlled from this NCU.Link axes can be assigned dynamically to channels of another NCU.Link axes are not local axes from the perspective of a particular NCU.The axis container concept is used for the dynamic modification of the assignment to an NCU.Axis substitution with GET and RELEASE from the parts program is not available for link axes.Prerequisite The participating NCUs,NCU1 and NCU2,must be connected by means of high-speed communication via the link module.The axis must be configured appropriately by machine data.The link axis option must be installed.Description The position control is implemented on the NCU on which the axis is physically connected to t
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