金属切削加工毕业设计英文翻译(共5页).doc

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1、精选优质文档-倾情为你奉上 Metal-cutting process Metal-cutting processes are extensively used in the manufacturing industry. They are characterized by the fact that the size of the original workpiece is sufficiently large that the final geometry can be circumscribed by it ,and that the unwanted meterial is remov

2、ed as chips,particles ,and so on. The chips are a necessary means to obtain the desired tolerances, and surfaces. The amount of scrap may vary from a few percent to 70%80% of the volume of the original work material.Owing to the rather poor material utilization of the metal-cutting processes, the an

3、ticipated scarcity of materials and energy, and increasing costs,the development in the last decade has been directed toward an increasing application of metal-forming processes. However, die costs and the capital cost of machines remain rather high; consequently, metal-cutting processes are, in man

4、y cases, the most economical, in spite of the high material waste,which only has value as scrap. Therefore, it must be expected that the material removal processes will for the next few years maintain their important position in manufacturing. Furthermore, the development of automated production sys

5、tems has progressed more rapidly for metal-cutting processes than for metal-forming processes. In metal-cutting processes, the imprinting of imformation is carried out by a rigid medium of transfer, which is moved relative to the workpiece, and the mechanical energy is supplied through the tool. The

6、 final geometry of the tool and the pattern of motions of the tool and the workpiece. The basic process is mechanical: actually, a shearing action combined with fracture.As mentioned previously, the unwanted material in metal-cutting processes is removed by a rigid cutting tool ,so that the desired

7、geometry, tolerances, and surface roughness are obtained. Examples of processes in this group are turning, drilling, reaming, milling, shaping, planing, broaching, grinding, honing, and lapping. Most of the cutting or machining processes are bases on a two-dimensional surface creation,which means th

8、at two relative motions are necessary between the cutting tool and the work material. These motions are defined as the primary motion, which mainly determines the cutting speed, and the feed motion, which provides the cutting zone with new material. In turning the primary motion is provided by the r

9、otation of the workpiece,and in planing it is provided by the translation of the table; in turning the feed motion is a continuous translation of the tool, and in planing it is an intermittent translation of the tool. Cutting Speed The cutting speed v is the instantaneous velocity of the primary mot

10、ion of the tool relative to the workpiece(at a selected point on the cutting edge). The cutting speed for turning,drilling, and milling processes can be expressed as V=dn m/minWhere v is cutting speed in m/min,d the diameter of the workpiece to be cut in meters, and n the workpiece or spindle rotati

11、on in rev/min. thus v, d, and n may relate to the work material or the tool, depending on the specific kinematic pattern. In grinding the cutting speed is normally measured in m/s.Feed The feed motion f is provided to the tool or the workpiece and, when added to the primary motion, leads to a repeat

12、ed or continuous chip removal and the creation of the desired machined surface. The motion may proceed by steps or continuously. The feed speed vf is defined as the instantaneous velocity of the feed motion relative to the workpiece(at a selected point on the cutting edge) For turning and drilling,

13、the feed f is measured per revolution (mm/rev) of the workpiece or the tool; for planing and shaping f is measured per storke (mm/stroke) of the tool or the workpiece. In milling the feed is measured per tooth of the cutte fz (mm/touth); that is,fz is the displacement of the workpiece between the cu

14、tting action of two successive teeth。The feed speed vf（mm/min）of the table is therefore the product of the number of the teeth z of the cutter ,the revolutions per minute of the cutter n,and the feed per tooth (vf=nzfz) . A plane containing the directions of the primary motion and the feed motion is

15、 define as the working plane, since it contains the motions responsible for the cutting action.Depth of Cut (Engagement) In turning the depth of cut a (sometimes also called back engagement) is the distance that the cutting edge engages or projects below the original surface of the workpiece. The de

16、pth of cut determines the final dimensions of the workpiece. In turning, with an axial feed, the depth of cut is a direct measure of the decrease in radius of the workpiece and with radial feed the depth of cut is equal to the decrease in the length of workpiece. In drilling, the depth of cut is equ

17、al to the diameter of the drill. For milling, the depth of cut is defined as the working engagement ae and is the radial engagement of the cutter. The axial engagement (back engagement) of the cutter is called ap. Chip Thickness h1 in the undeformed state is the thickness of the chip measured perpen

18、dicular to the cutting edge and in a plane perpendicular to the direction of cutting. The chip thickness after cutting (i.e., the actual chip thickness h2) is larger than the undeformed chip thickness, which means that the cutting ratio or chip thickness ratio r=h1/h2 is always less than unity.Chip

19、Width The chip width b in the undeformed state is the width of the chip measured along the cutting edge in a plane perpendicular to the direction of cutting.Area f Cut For single-point tool operations, the area of cut A is the product of the undeformed chip thickness h1 and the chip width b (i.e., A

20、=h1b).The area of cut can also be expressed by the feed f and the depth of cut a as follows: h1=f sink and b=a/sink (27.2) where k is the major cutting edge angle (i.e.,the angle that the cutting edge forms with the working place).Consequently, the area of cut is given by A=fa 金属切削加工金属切削加工被广泛应用于制造业。

21、他们的特点是工件在加工前有足够的尺寸，可以将工件的最终几何形状尺寸包含在里面。不需要的材料以颗粒，切屑的方式被去除。去除切屑是获得所要求的工件几何形状，尺寸公差和表面质量的一个必要的手段。废料的数量多少不一，可能会占工件体积的从百分之几到70 80 不等。金属切削加工中，由于材料利用率较差，加之预计到缺乏原料和能源和成本的增加，在过去十年发展中，金属成形加工应用越来越广。但是，金属成形加工的模具的成本和设备成本仍然相当高，因此尽管金属切削加工材料浪费严重，但在许多情况下仍然是最经济的。因此金属切削加工将在今后几年保持其在制造业的重要地位。此外，金属切削加工自动化生产系统的发展比金属成形加工自动

22、化生产系统的发展快得多。在金属切削加工中，信息的传递是通过刚性传递介质（刀具）实现的，刀具相对工件运动，机械能通过刀具作用于工件。因此，刀具的几何形状和刀具与工件运动方式决定了工件的最终形状。这个基本过程是机械过程，事实上是一个剪切和断裂相结合的过程。如前所述，多余材料在金属切削加工中是通过去刚性切削刀具去除掉的，以获得使所需的几何形状，公差和表面粗糙度的结果。属于这种加工方法的例子有：车削，钻孔，铰孔，铣削，牛头刨削，龙门刨削，拉削，磨削，珩磨和研磨。大多数切削加工或机械加工是在二维表面成型法上建立的，这意味着是必要的切割工具和工件材料得有两种相对运动。一种被称为主要运动，主要确定的切削速度

23、和另一种被称为进给运动，它提供了切割带新的材料。车削时工件的主运动是回转运动，龙门刨床刨削时，工作台的直线运动是主运动;车削时，刀具的连续直线运动是进给运动。而在龙门刨床的刨削中，刀具的间歇运动是进给运动。切削速度：切削速度v切削刀具（切削刃上在选定的点） 相对于工件的瞬时速度 。切削速度车削，钻孔，铣加工可表示为V = dn m/min式中V为切削速度，单位为米/分; d是该工件将要切削部分的直径，单位是米;n工件或主轴转速，单位是转/分。但是v，d,n的意义可能有所不同，这取决于具体的运动模式。在磨削的切削速度通常是米/秒。进给量f除了主运动，当刀具或工件作进给运动时，将会导致了重复或连续

24、的切屑被去除从而创造理想的加工表面。进给运动可以是间歇的或是连续的。进给速度vf的定义是选定切削刃上一点相对于工件的速度。对于车削和钻削，进给量f以工件或刀具的每转的相对移动量来表示；对于龙门刨削和牛头刨削，进给量f以刀具或工件每次行程的相对移动量来表示；对于铣削来说，以刀具的每齿进给量fz来表示。每齿进给量fz是相邻两齿之间的距离。所以工作台的进给速度vf是刀具齿数z，刀具每分钟转数n和进给速度fz的乘积。包含主运动方向和进给运动方向的平面被定义为工作平面，因为该平面包含决定切削作用的两种基本运动。切削深度（吃刀深度）车削的切削深度a（有时也被称为背吃刀量）是刀具切削刃切进或深入工件表面的距

25、离。切削深度决定了最后的尺寸工件。在切削加工中采用轴向进给时，切削深度可以通过直接测量工件半径减少量来确定；在切削加工中采用径向进给时，切削深度等于工件长度的减少量。在钻削中，切削深度等于钻头的直径。对于铣削，切削深度定义为侧吃刀量ae，它等于铣刀径向吃刀深度，而铣刀轴向吃刀深度（背吃刀量）被称为ap。切屑厚度未变形状态时的切削厚度h1，就是在垂直于切削方向的平面内垂直于切削刃测量得到的切屑厚度。切削后的切屑厚度（即切屑的实际厚度h2）大于未变形时的切屑厚度，这意味着削减比或切屑厚度比R = h1/h2总是小于一。 切削宽度 未变形状态的切削宽度b 是在与切削方向垂直的平面内眼切削刃测得的切屑宽度。切削面积 对于单刃刀具的切削加工，切削面积A是为变形的切屑厚度h1和切削宽度b的乘积（即A=h1*b）。切削面积也可以用进给量f和切削深度a来表示如下： H1=f*sink 及 b=a/sink式中k为主偏角（即切削刃与工作平面成的夹角）。因此，可以由下式求出切削面积： A=f*a 专心-专注-专业