资源目录
压缩包内文档预览：
编号：532194
类型：共享资源
大小：525.51KB
格式：ZIP
上传时间：2015-11-25
上传人：QQ28****1120
认证信息
个人认证
孙**（实名认证）
辽宁
IP属地：辽宁
6
积分
- 关 键 词：
-
机械毕业设计英文翻译
- 资源描述：
-
英文翻译外文文献翻译466单刃刀具,机械毕业设计英文翻译
- 内容简介：
-
第 1 页 共 7 页 译文 : Single Point Tools Single-point tools are cutting tools having one cutting part (or chip producing element) and one shank. They are commonly used in lathes, turret lathes, planers, shapers, boring mills, and similar machine tools. A typical single-point tool is illustrated in Fig.2.30. The most important features are the cutting edges and adjacent surfaces. These are shown in the figure and defined as follows: the face is the surface or surface over which the chip flows. The flank is the tool surface or surfaces over which the surface produced on the work-piece passes. The cutting edge is that edge of the face which is intended to perform cutting. The tool major cutting edge is that entire part of the cutting edge which is intended to be responsible for the transient surface on the work-piece. The tool minor cutting edge is the remainder of the cutting edge. The corner is the relatively small portion of the cutting edge at the junction of the major and minor cutting edges; it may be curved or straight, or it may be the actual intersection of these cutting edges. nts第 2 页 共 7 页 In general, when a tool is applied to a work-piece, its motion relative to the work-piece has two components: The motion resulting form the primary motion of the machine tool, which can be called the primary motion of the tool. The motion resulting form the feed motion of the machine (Fig.2.31). The resultant of these two tool motions is called the resultant cutting motion and is defined as the motion resulting from simultaneous primary and feed motions. It should be noted that in machine tools where the feed is applied while the tool is not engaged with the work-piece (as in shaping or planning, for example ),the resultant cutting motion is identical to the primary motion. When the feed motion is applied continuously, the angle between the direction of primary motion and the resultant cutting direction is called the resultant cutting-speed angle . This angle is usually extremely small and for most practical purposes can be assumed to be zero. nts第 3 页 共 7 页 Further, the cutting speed , the instantaneous velocity of the primary motion of the selected point on the cutting edge relative to the work-piece, can vary along the major cutting edge. The feed speed f, the instantaneous velocity of the feed motion of the selected point on the cutting edge relative to the work-piece, is constant. Finally, the resultant cutting speed e,the instantaneous velocity of the resultant cutting motion of the selected point on the cutting edge relative to the work-piece, is given by , cose,but since for most practical operations is very small, it can generally be assumed that , e. One of the important tool angles when considering the geometry of a particular machining operation is the angle in Fig.2.32 called the major cutting-edge angle r .The thickness of the layer of material being removed at the selected point on the cutting edge, known as the under-formed chip thickness chip thickness ca,significantly affects the power required to perform the operation. Strictly, this dimension should be measured both normal to the cutting edge and normal to the resultant cutting direction. However, for all practical purposes, since is small, as described above, cacan be measured normal to the direction of primary motion; thus in Fig.2.32 and all subsequent figures, cawill be measured this way. From Fig.2.32, therefore, cais given by farsin , where fais the feed engagement, the instantaneous engagement of the tool cutting edge with the work-piece measured in the direction of feed motion. For single-point cutting operations fais equal to the feed, and therefore, ca rf sin. The cross-sectional area cAof the layer of material being removed nts第 4 页 共 7 页 (cross-sectional area of the uncut chip) is approximately giver by, pc faA ,where pais the base engagement, previously known as depth of cut. The back engagement is the instantaneous engagement of the tool with the work-piece, measured perpendicular to the plane containing the directions of primary and feed motion(Fig.2.31). In general the back engagement determines the depth of material removed from the workpiece in a single point cutting operation. Jigs and Fixtures It has already been stated the work-piece must be located relative to the cutting tool, and be secured in that position. After the work-piece has been marked out, it is still necessary to position it with respect to the machine movement, and to clamp it in that position before machining is started. When several identical work-piece are to be produced the need to mark out each part is eliminated by the use of jigs and fixtures, but if a casting or forging is involve, a trail work-piece is marked out, to ensure nts第 5 页 共 7 页 that the work-piece can be produced from it, and to ensure that ribs, cores, etc. have not become misplaced. Jigs and fixtures are alike in that they both incorporate devices to ensure that the work-piece is correctly located and clamped, but they fifer in that they both incorporate means of tool guiding during the actual cutting operation, and fixtures do not. In practice ,the only cutting tools that can be guided while actually cutting are drills, reamers, and similar cutters; and so jigs are associated with drilling operations, and fixtures with all other operations. Fixtures may incorporate means of setting the cutting tools relative to the location system. The advantage of jigs and fixtures can be summarized as follows: 1. marking out and measuring and setting out methods are eliminated; 2. unskilled workers may proceed confidently and quickly in the knowledge that the work-piece can be positioned correctly, and the tools guided or set; 3. the assembly of parts is facilitated, since all components will be identical within small limits, and trying and filing of work is eliminated; 4. the parts will be interchangeable, and if the product is sold over a wide area, the problem of spare parts will be simplified. Bolt holes often have 1.5mm or even 3.0mm clearance for the bolt, and reader may doubt the necessity of making precision jigs for such work. It must remembered that the jigs, once made, will be used on many components, and the extra cost of an accurately made jigs is spare over a large output. Further more, it is surprising how small errors accumulate in a mechanism during its assembly. When a clearance is specified, it is better to ensure its observance, rather than allow careless marking out and machining to encroach upon it. (1)the location of work-piece. Fig 2.27 represent a body that is completely free in space; in this condition it has six degrees of nts第 6 页 共 7 页 freedom. Consider these freedom, with respect to the three mutually perpendicular axes XX,YY and ZZ. The body can move along these axes; it therefore has three freedoms of translation. It can also rotate about any of the three axes; it therefore has three freedoms of rotation .the total number of freedoms is six. When work is located, as many of these freedoms as possible must be eliminated, to ensure that the operation is performed with the required accuracy. Accuracy is ensured by machining suitable location features as early as possible, and using them for all location, unless other considerations mean the other location features must be used. If it is necessary, the new location features must be machined as a result of location from the former location features. (2) The clamping of the work-piece. The clamping system must be such that the work-piece is held against the cutting forces, and the clamping force must not be so great as to cause the work-piece to become distorted or damaged. The work-piece must be supported beneath
- 温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。
川公网安备: 51019002004831号