第1章 金属切削的基本定义

null第1章 金属切削的基本定义第1章 金属切削的基本定义Contents1.1 切削运动与切削用量1.2 刀具结构及几何参数1.4 旋转刀具的几何角度1.5 切削层参数与切削方式(BASIC DEFINITION OF METAL CUTTING(Cutting motion and cutting regime)(Cutting tool angles)(Rotating cutting angles）(Parameters of cutting layer and cutting mode)School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础1.3 刀具角度的换算(Tool angle conversion )null1.1 切削运动与切削用量一、切削加工的概念通过机床提供的切削运动和动力，使刀具和工件产生相对运动，从而切除工件上多余的材料，以获得合格零件的加工过程。 The metal cutting is the process in which the excess metal on a blank is cut off by a cutting tool, and formed into a required part. 在现代机械制造中，除少量零件采用精密铸造、精密锻造、粉末冶金等到方法直接获得零件外，大部分零件都要经过切削加工才能获得所需要的加工精度和表面粗糙度。 In modern manufacturing industrial, most of parts which machined precision and roughness of machined surface are formed by cutting, lest of that are formed by precision casting, precision forging, and powder metallurgy etc.·(Cutting motion and cutting regime)(What is metal cutting?)School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null 1) 刀具和工件间要有形成零件结构要素所需的相对运动 (cutting motion)。 2) 刀具材料的性能能够满足切削加工的需要(cutting tool materials)。 3) 刀具必须具有一定的几何角度(cutting tool angles)。切削加工必须具备的基本条件 (basic requirements of metal cutting)School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null二、零件表面的形成 (Formation of part surface)1. 工件表面的形状 (Shape of part surface)零件的表面平面（plane）圆柱面（ cylindrical surface ）特殊表面（ special surface ）成型表面（ formed surface ）圆锥面（ circular conical surface ）Surface shape of partSchool of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null图1-1所示表面都属于线性表面，该表面是由一条线（母线）沿着另一条线（导线）运动而形成的轨迹。母线和导线统称发生线。母线与导线可互换的表面称为可逆表面，反之为不可逆表面。 As shown in Figure 1-1, there are some similar features that the surfaces of the parts are lineal surface formed by a relative motion that a line (generatrix) moves along another line (lead). The generatrix and the lead are called generant line. If the generatrix and the lead are interconvert, the formed surface by them is called reversible surface, on the contrary, is called irreversible surface. 2. 工件表面的形成方法及所需运动 （Forming of surface of the work piece and its required motion） 机械制造技术基础School of mechanical engineering 第1章 金属切削的基本定义 null图1-1 构成机械零件外形廓形的常用表面 1—平面 2—圆柱面 3—圆锥面 4—螺旋面 5—回转体平行面 6—渐开线柱面 Fig.1-1 the surface of part in the machine 1—plane 2—cylindrical surface 3—circular conical surface 4—helicoid 5—spheroid 6—involute机械制造技术基础School of mechanical engineering 第1章 金属切削的基本定义 null图1-2 零件表面的形成(Formation of surface of parts) 1—母线(generatrix) 2—导线(lead)机械制造技术基础School of mechanical engineering 第1章 金属切削的基本定义 null机械制造技术基础School of mechanical engineering 第1章 金属切削的基本定义 Fig.1-3 母线原始位置变化时形成的不同表面 The surface formed by the position change of genertrix 1—母线与轴线平行( the genertrix is parallel to the axis ) 2—母线与轴线相交(the genertrix intersects the axes at a point) 3—母线与轴线异面(the genertrix and the axes are not in same plane)null（1）轨迹法（tracing） 切削刃与被加工表面为点接触，接触点按一定规律的轨迹运动形成发生线（一般为母线），采用轨迹法形成发生线需要一个独立的成形运动。 In tracing, the cutting edge touches the working surface at a point moving along the generatrix, which needs a independent forming motion. School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础 机床上形成发生线的方法主要有四种： There are four methods of forming the generant line.（2）成形法（Forming） 切削刃为一条切削线，与要形成的发生线完全一致，不需要专门的成形运动。 In forming, the cutting edge accords with the generatrix, the special formation motion is unnecessary.null （3）相切法（tangency） 采用旋转刀具加工时，在垂直于刀具轴线的端面内，切削刃可以看成一个切削点，切削时刀具除了绕自身轴线的旋转外，它的轴线还需要按一定的规律作轨迹运动，此时切削点运动轨迹的下包络线就形成了发生线，用相切法形成发生线需要两个独立的成形运动。 In tangency, the cutting tool revolves around its axes and moves along the genera trix, the generant line is the enveloping line of the trace of a point on cutting edge, the tangency needs two independent formation motions.School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null （4）展成法 (generating) 刀具切削刃的形状为一条切削线，它与需要形成的发生线不吻合，切削时，刀具切削线与发生线相切触，切削线包络出发生线，需要一个复合运动。 In generating, the cutting edge is not accord with the generant line but is tangential to the generant line, the generant line is the enveloping line of cutting edge, the generating needs a combination motion.School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null三、工件加工表面 (Surface on work piece) 待加工表面—— 工件上即将切除的表面. Work piece surface to be cut——the surface from which the excess metal will be cut off. 2. 已加工表面——工件上已经切除而形成的新表面. Machined surface——surface—the new surface from which the excess metal has already been cut off. 3. 过渡表面——工件上正在切削的表面，介于已加工表面和待加工表面之间. Cutting surface——the surface that is being cut.School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null四、切削运动 (cutting motion) 1. 主运动 (main motion) 由机床提供的刀具与工件间主要的相对运动，使刀具切削刃切入工件材料的运动。速度最高、消耗功率大、通常只有一个,不考虑进给运动的条件下，切削刃上选定点相对于工件的瞬时运动方向. It is the most necessary and important motion in the process of removing the excess metal from the work piece. In general, it is taken as the maximum cutting speed on the work piece or cutter and utilizes the most machine power. There is only one main motion in a cutting process. For turning and boring, the main motion is relative rotation between work piece and cutting tool.School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null 2. 进给运动 (feed motion) 使主运动能够连续进行，切除工件上多余材料, 形成满足一定要求的已加工表面的运动，或者定义为保证切削加工过程得以持续进行所需的运动。进给运动可以是连续的运动，也可以是间歇的运动。 Feed is the rate which the cutting tool advances into the work piece. It makes the cutting process continue so that the machined surface is produced. Feed motion may be continuous motion or intermittent motion.School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null3. 合成切削运动 (Combination of cutting motion and combined speed) 当主运动与进给运动同时进行时，由主运动和进给运动合成的运动。刀具切削刃上选定点相对于工件的瞬时合成运动方向，其速度为合成切削速度，该速度方向与过渡表面相切。 When the main motion and the feeding motion are carried out simultaneously, the relative motion of a certain point on the cutting edge against the workpiece is referred to as the combination of cutting motions. The combined speed is equal to the vector sum of the main motion plus the feeding speed, namely.School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null Fig. 1-4 (2) Cutting motions in drilling, milling, grinding(e) Drilling (e) Grinding (e) End milling(e) Slab millingSchool of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null【定义】刀具切削刃上选定点相对于工件主运动的速度(The relative speed between the main motion and the certain point on cutting edge )。 【计算方法】由于切削刃上各点的切削速度可能是不同，主运动为旋转运动时常用最大切削速度代表刀具的切削速度。(In most cutting processes the main motion is circular motion. For circular motion the cutting speed is)（Cutting speed）School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null在主运动每转一转或每一行程时，刀具在进给运动方向上相对于工件的位移量，单位是mm/r(用于车削、镗削等)或mm/d。str(毫米/双行程) (用于刨削、磨削等)，进给量表示进给运动的速度。进给运动速度还可以用进给速度（单位mm/s)或每齿进给量 (用于铣刀、铰刀等多刃刀具，单位是mm/齿)表示。 Feed is the relative displacement between the work piece and the cutter along the direction of feeding motion per revolution or per stock. mm/r (The tool or the work piece reciprocates, such as planning ) or mm/d. str. (double stroke) (The tool or the work piece rotates, such as turning, grinding, drilling etc.). For multiple teeth cutting tools such as milling cutter reamer, broach, gear hob etc. feed may be measured in millimeters per tool tooth. Obviously （feed）School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础wherenull 在垂直于主运动方向和进给方向的工作平面内测量的刀具切削刃与工件切削表面的接触长度。它是主切削刃的工作长度在包含主运动和进给运动速度的平面的垂线上的投影长度。对于外圆车削，背吃刀量为工件上已加工表面和待加工表面间的垂直距离，单位为mm。 Black engagement of the cutting edge is the length of interface of the cutting edge and workpiece, which is measured in the plane that is perpendicular to the direction of main motion and feeding. For turning and planning, the black engagement of the cutting edge is equal to the normal distance between the machined surface and the work piece to be cut.(Black engagement of the cutting edge)School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础nullSchool of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础For cylindrical turning（1-3） ——Diameter of work piece surface to be cut (mm)； ——diameter of machined surface (mm)。 WhereFor drilling（1-4） null1.2 刀具结构及几何参数一、刀具结构(The elements of turning cutting tool)12345671——major cutting edge 2——major flank 3——tool nose 4——minor flank 5——minor cutting edge 6——rake face 7——tool arborFigure 1-5 working part of typical turning toolSchool of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null二、刀具静止参考系（Reference system for the marked angles of cutting tool）用于定义刀具设计、制造、刃磨和测量时刀具几何参数的参考系。 只考虑主运动即切削速度反向，不考虑进给运动的影响，并且假定主刃选定点安装于工件中心高度，刀杆中心线垂直于进给方向。基于以上特征的参考平面定义如下： The reference system for marked angles of cutting tool is the reference system which is used for designing, manufacturing, sharpening, and measuring the geometric parameters of cutting tool. For any cutting tool some working conditions can be predetermined in advance: (1) Predetermined condition for motion Assume the direction of main motion is the direction of cutting speed, feeding motion is not taken into consideration. (2) Predetermined condition for set up Assume the base plane of tool for grinding and setup to be normal to the cutting edge plane or parallel to the reference plane. School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null【基面Pr】(Tool reference plane) 过定点垂直于合成切削速度向量的平面。车刀基面是车刀的安装面。 【切削平面Ps】(Tool cutting edge plane)在刀刃上选定点与工件的过渡表面相切的平面。此时的Ps包含了刀刃在其选定点的切线和切削速度向量。或者定义为：过定点的切削刃的切线与切削速度向量组成的平面。 【正交平面Po】(Main section or main section reference system )过主切削刃上选定点并垂直于切削平面和基面的平面。或过主切削刃上选定点并垂直于切削刃在基面上投影的平面。 【法平面Pn】(Normal section and normal section reference system)过主切削刃上选定点并垂直于切削刃或主切削刃在该点的切线的平面。Chapter one Basic definition of metal cuttingnull【背平面Pp、假定工作平面Pf 】(Transverse section, longitudinal section)过主切削刃上选定点平行于刀杆轴线并垂直于基面的平面。过主切削刃上选定点同时垂直于刀杆轴线和基面的平面。正交平面、法平面、假定工作平面和背平面又统称为测量平面，用不同的测量平面分别与基面、切削平面组合就形成不同的参考坐标系，包括正交平面参考系、法平面参考系、假定工作平面和背平面参考系。 各参考坐标平面的位置及相互关系如下页表所示。School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null（a）main section system and normal section system (正交平面与法平面参考系) （a）transverse section or longitudinal section system (假定工作平面与背平面参考系)Base plane of tool arborDesignated point on cutting edgeBase plane of tool arborDesignated point on cutting edgeSchool of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础nullSchool of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null三、刀具标注角度(marked angles of the cutting tool)刀具的标注角度是指刀具上的切削刃、刀面与参考系中各参考平面间的夹角，用以确定切削刃、刀面的空间位置。下面根据刀具几何角度的作用给予介绍： Marked angles of the cutting tool are the azimuth angles between the cutting edge and the tool surface determined in the reference system for marked angles, which can determine the position of the cutting edge and tool surface in the reference system. Based on the roll of the marked angles, some marked angles in the main reference system are described. School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null1. 确定刀具主切削刃空间位置的几何角度Tool cutting edge inclination angle —the included angle between the major cutting edge and the tool reference plane, which is measured in the tool cutting edge plane. Cutting edge angle —the included angle between the projection of the major cutting edge on the tool reference plane and the direction of feeding. It is negative if the tool nose is the lowest point on the cutting edge. And it is positive if the tool nose is the highest point on the cutting edge. It is called orthogonal cutting if the cutting edge is parallel to the tool reference plane.School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null2. 确定刀具主前刀面Aγ和主后刀面Aα空间位置的几何角度Rake angle——the included angle between the rake face and the tool reference plane, which is measured in main section which passes though the designated point on major cutting edge. Clearance angle——the included angle between the major flank and the tool cutting edge plane, which is measured in main section which passes though the designated point on major cutting edge. School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null3. 确定刀具副切削刃空间位置的几何角度4. 确定副后刀面Aα空间位置的几何角度 Minor cutting edge angle —the included angle between the projection of the minor cutting edge on the tool reference plane and the direction of feeding. Minor clearance angle——the included angle between the minor flank and the tool cutting edge plane, which is measured in minor section which passes though the designated point on minor cutting edge. School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null5. 派生角度(Derivative angles )Wedge angle——the included angle between the rake face and the major flank, which is measured in main section which passes though the designated point on major cutting edge. Tool included angle——the included angle between the projection of major cutting edge and minor cutting edge, which is measured in tool reference plane. Tool approach angle——the included angle between the projection of major cutting edge on tool reference plane and the normal line of feeding direction.School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null一般情况下，刀具工作图上需要标注的基本角度有6个：其他角度可以通过上述角度派生出来特殊刀具（铣刀、成形车刀）角度的标注可规定采用法平面、假定工作平面、背平面中标注前后角。School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null 如前所述，刀具的标注角度是在忽略进给速度的影响，且刀具安装在理想工作位置的情况下确定的。当刀具进入工作状态后，选定点的实际切削速度的方向以及刀具的实际安装位置相对于假定的理想状态发生了变化，由此而建立的工作参考系(动态参考系)相对于标注参考系(静态参考系)在空间位置上也相应改变，因此刀具的实际切削角度(即刀具的工作角度)和标注角度不一样。 As stated above, all the marked angles for cutting tools are the angles under the predetermined conditions that the feeding motion is not taken into considerat-ion and the position to set up is ideal. When the predetermined conditions are changed, the reference system for cutting will also be changed. The angles determined by the reference system in cutting are called working angles.四、刀具的工作角度（working angles of cutting tool）School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null1. 进给运动的影响(Influence of feeding motion on working angles) (1) 纵向进给的影响(Influence of longitudinal feeding motion ) 如下页图示，纵向走刀车外圆时，主切削刃上选定点A的合成切削速度 。在假定工作平面(进给平面)Pf 内， 相对于 偏转角度 ，因此，选定点A处的工作侧前角 和工作侧后角 分别为其中：School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础nullConclusions: The smaller the diameter d, the greater the value changed in the angle. In practice, the value of uf is no more than 30’~ 40’, and can be neglected. In screw cutting, especially in screw cutting of multiple threads, the value of uf is quite large, its working angles must be calculated.Fig.1-5 working angles in turningSchool of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null A点假定工作平面内前、后角的变化，可换算至正交平面内，其变化量 为： (1-6) (1-5)School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null结论: 纵向车削时，主切削刃的工作前角比标注前角增大，工作后角比标注后角减小(副切削刃情况刚好相反)。 在纵车外圆时，由于工件进给量相对于直径很小，故因纵向进给运动而引起的刀具角度变化也很小，可忽略不计； 在车螺纹(尤其是车多头螺纹)时，由于工件直径相对于进给量较大，纵向进给运动对刀具角度的影响就不容忽视，应该适当加大主切削刃后角和副切削刃前角，或者采用斜刀垫使刀具后面偏离工件过渡表面。School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null(2)横向进给的影响（Influence of transverse feeding motion）。 如图1.6所示，横向走刀车槽或切断时，切削刃上选定点A的实际切削速度为 。在假定工作平面(进给平面)内， 相对于 偏转角度 ；A点的运动轨迹为阿基米德螺旋线。由于 方向的偏转，故其工作前、后角分别为：School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null结论（conclusion） 在横进给车削中，当进给量一定时，随着切削刃不断趋近工件中心(即不断减小)，其工作前角不断增大，工作后角不断减小。当刀尖接近工件中心时，工作后角迅速减小，最容易因后面和工件过渡表面剧烈摩擦而崩刃，应当引起充分重视。以横进给为主工作的刀具(如切断刀、车槽刀和径向成形车刀等)，应当适当加大标注后角。 School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础2.安装位置的影响（Influence of setup for cutting tool on working angles ）2.安装位置的影响（Influence of setup for cutting tool on working angles ） (1) 刀尖高低的影响（influence locating position for tool nose on working angles）。 安装位置高于(或低于)工件中心(如图l.7所示为安装位置偏高的情况， 0°)时，即使不考虑进给运动的影响，该点主运动速度方向也将在背平面内相对于工件中心高处偏转角度 ，从而导致工作参考系相对于静参考系在内相应偏转角度 . When the tool nose is higher than the center line of workpiece,the longitudinal working rake angle will be increased and the longitudinal clearance angle will be decreased. School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础nullFig1-10 Influence of locating position for tool nose on working anglesSchool of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null 则选定点的工作背前角 和工作背后角 为： 注：当安装位置偏高时，用上边符号；当安装位置偏低时，用下边符号。 选定点背平面内的前、后角变化量转换到起正交平面内时，前、后角 变化量为 式中：H——刀杆高度(mm)。School of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null如右图所示，刀杆安装倾斜将直接引起车刀的工作主偏角和工作副偏角变化。 when the center line of the tool bar is not perpendicular to the direction of feeding,the major and minor cutting edge angles will vary with the included angle between the normal line of the feeding direction and the center line of the tool bar.(2)刀杆位置的影响（Influence of the direction for the center of the tool bar on working angles ）Fig.1-11 Influence of the direction for the center of the tool bar on working anglesSchool of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null一.刀具角度换算的目的（why do we convert the tool angle） （1）为了刀具设计、制造和刃磨的需要，常常要知道正交平面内刀具标注角度与法平面以及假定工作平面、背平面参考系内的标注角度之间的换算关系。 （2）特别是螺旋刃铣刀以及其它切削刃为曲线的复杂刀具，它们的标注角度不再正交平面内，其国家的参考角度却是在正交平面内的角度。1.3 刀具角度的换算 （Tool angle conversion in different system ）It is necessary to convert the marked angle from one system to another system in tool design and manufacturing. i.e, among main section system,normal section system, transverse system and longitudinal systemSchool of mechanical engineering 第1章 金属切削的基本定义 机械制造技术基础null二、刀具角度换算的方法(Method of conversion of tool angle)1.立体几何的线面法(Solid geometry)（1）正交平面和法平面间的换算 (tool angle conversion from main section to normal section) （图1）（2）任意剖面和正交平面间的换算（tool angle conversion from main section to any section ）（图2）（1）（2）School of mech