Unit 3 Lesson 7

1、Professional English for Mechanical Engineering Lecturer: Xiaobin CuiPart II Interchangeability and MeasurementLesson 7 Working DrawingLesson 7Working Drawing Working drawing are the drawings from which a design is implemented. All principles of orthographic projection and techniques of graphics can

2、 be used to communicate the details of a project in working drawings. A detail drawing is a working drawing of a single part (or detail) within the set of working drawings.Definitionsworking drawing工作图,施工图orthographic , :rfik adj.正投影的 orthographic projection 正投影detail drawing 详图 零件图在工作图中，所有正交投影法则法则和

3、图形技技术术均可用可用来表达设计方案的细节。Lesson 7Working Drawing Specifications are the written instructions that accompany working drawings. When the design can be represented on a few sheets, the specifications are usually written on the drawings to consolidate the information into a single format.Definitionsspecifi

4、cations ,spsfken n. 技术要求当设计内容在多张图纸上表达时，通常在工作图上注明技术要求注明技术要求，从而确保图纸信息的统一性。consolidate knslideit vt.巩固，统一，整理All parts must interact with parts to some degree to yield the desired function from a design. Before detail drawings of individual parts are made, the designer must thoroughly analyze the workin

5、g drawing to ensure that the parts fit properly with mating parts, that the correct tolerances are applied, that the contact surfaces are properly finished, and that the proper motion is possible between the parts. Lesson 7Working DrawingYield 产生，形成mating parts 配合件tolerance tlrns n.公差；规定公差 在绘制单个零部件的

6、详图之前，设计人员设计人员必须对工工作图作图进行充分分析分析，以确保零部件之间的配合良好、采用正确的公差、可对接触面进行合理的加工，以及零部件之间能够产生合理的运动。RequirementsMuch of the work in preparing working drawings is done by the drafter, but the designer, who is usually an engineer, is responsible for their correctness. It is working drawings that bring products and sys

7、tems into being. Working drawings are legal contracts that document the design details and specifications as directed by the engineer. Therefore drawings must be as clear, precise, and thorough as possible. Lesson 7Working Drawingbringinto being 使出现，实现，产生，建立工作图的许多准备工作工作是由绘图员来完成完成的，而图纸的正确性则要由设计者负责，设计

8、者通常是工程师。RequirementsRevisions and modifications of a project at the time of production or construction are much more expensive than when done in the preliminary design stages. Poorly executed working drawings result in wasted time and resources and increase implementation costs. To be economically c

9、ompetitive drawings must be as error-free as possible.Lesson 7Working Drawing生产或施工中修订修订和更改更改设计方案所需成本成本要比初步设计阶段高高很多。RequirementsThe inch is the basic unit of the English system, and virtually all shop drawings in the U.S. are dimensioned in inches. The millimeter is the basic unit of the metric syste

10、m. Metric abbreviation (mm) after the numerals is omitted from dimensions because the SI symbol near the title block indicates that all units are metric.Lesson 7Working Drawingabbreviation ,bri:viein n. 缩写，缩写词title block 标题栏由于在标题栏附近的国际单位制（SI）符号标明所有单位为公制，因此尺寸数字后面的单位缩写单位缩写（mm）要省略省略标注。RequirementsSome

11、working drawings carry both inch and millimeter dimensions, usually the dimensions in parentheses or brackets are millimeters. The units may also appear as millimeters first and then be converted and shown in brackets as inches. Converting from one unit to the other results to fractional round-off e

12、rrors. And explanation of the primary unit system for each drawing should be noted in the title block.Lesson 7Working Drawingparenthesis prenisis n. 圆括号bracket brkit n.方括号有些图纸图纸的尺寸单位既有英寸有英寸也有毫米毫米，通常在圆括号或方括号中的尺寸以毫米为单位.fractional frknl adj.分数的，小数的round-off 四舍五入，抹去零头RequirementsTitle Blocks In practice

13、，title blocks usually contain the title or part name, drafter, date, scale, company, and sheet number. Other information, such as tolerances, checkers, and materials, also may be given. Any modifications or changes added after the first version to improve the design is shown in the revision blocks.

14、Depending on the complexity of the project, a set of working drawings may contain from one to more than a hundred sheets. Therefore, giving the number of each sheet and the total number of sheets in the set on each sheet is important (for example, sheet 2 of 6, sheet 3 of 6, and so on).Lesson 7Worki

15、ng DrawingTitle Blocks Parts List The part numbers and part names in the parts list correspond to those given to each part depicted on the working drawings. In addition, the number of identical parts required is given along with the material used to make each part. If all working drawings in a set a

16、re the same scale, you need to indicate it only once in title block on each sheet. If several detail drawings on a working drawing are different scales, indicate them on the drawing under each set of views. In this case, indicate, “as shown” in the titleLesson 7Working Drawingpart list 零件明细表，材料清单as

17、shown 如图所示Part Listblock opposite scale. When a drawing is not according to the scale, place the abbreviation NTS (not to scale) in the title block.Part Names and Numbers Give each part a name and number, using letters and numbers 1/8-in. (3 mm) high. Place part numbers inside circles, called balloo

18、ns, having diameters approximately four times the height of the number. Place part numbers near the views to which they apply, so their association will be clear. Lesson 7Working Drawingnot to scale 不按比例part number 零部件序号将部件序号置部件序号置于直径约四倍数字高度的圆内，称为带圆圈的数字。Part ListPart Names and NumbersOn assembly dra

19、wings, balloons are especially important because the same parts numbers are used in the parts list. People who check drawings must have special qualifications that enable them to identify errors and to suggest revisions and modifications that result in a better product at a lower cost. Lesson 7Worki

20、ng Drawing 图纸审核员审核员必须具有有专业任职资格资格，才能识别错误，并能提出修订和修改方案，从而以相对较低的成本生产出较高质量的产品。Part Names and NumbersCheck and RevisionA checker may be chief drafter experienced in drafting and manufacturing processes or the engineer or designer who originated the project. In large companies, personnel in the various sho

21、ps involved in production review the drawings to ensure that the most efficient production methods are specified for each part.Lesson 7Working Drawing在大型公司，与生产相关的各部门要有专人人对图纸图纸进行复审复审，以确保每个零部件均已指定最有效生产方法。Check and RevisionCheckers never check the original drawing; instead, they mark corrections with a colored pencil on a blue-line print. They return the marked-up print to the drafter who revises the original and makes another print for final approval. Checkers inspect a working or detail drawing for correctness and soundness of design. In addition, they are responsible for th