این مطلب از جزوه تخصصی زبان فنی نقشه کشی صنعتی است که من از وبلاگ استاد دهقان براتون گرفتم 

ادامه مطلب رو بزنید

عزیزان متن زیر مخصوص دانشجویان زبان فنی نقشه کشی صنعتی میباشد .لذا به درس زبان عمومی ارتباطی ندارد و فقط قابل استفاده برای دانشجویان زبان فنی رشته نقشه کشی است.ده صفحه اول جزوه خوب تایپ نشده بود لذا از طریق وب لاگ آنرا در اختیار دانشجویان قرار داده ام.

دهقان

Drawings described

A drawing is a graphic representation of an idea. A concept or an entity which actually or potentially exists in life. The drawing itself is 1) a way of communicating all necessary information about an abstraction. Such as an idea or a concept; or 2) a graphic representation of same real entity. Such as a machine  part . a house , or a tool . for example.

Drawing is one of the  oldest forms of communication. Dating back even farther than verbal communication. Cave dwellers painted drawings on the walls of their caves thousands  of years before  paper was invented. These crude drawings served as e means of communication long before verbal communication had developed beyond the grunting stage. In later years. Egyptian hieroglyphics were a more advanced form of communicating through drawings.

The old adage “ one picture is worth a thousand words” is still the basis of the need for technical drawings.

 

Types of Drawings

There are two basic types drawings. Artistic and technical. Some experts there are actually three types. The two mentioned and another type which combines the two. The third type is usually referred to as an illustration or rendering.

Artistic Drawings

Artistic drawings range in scope from the most simple line drawings to the most famous paintings. Regard less of their complexity or status. Artistic drawings are used to express the feelings , beliefs , philosophies or abstract ideas of the artist. This is why the lay person often finds it difficult to understand what is begin communicated by a work of art.

In order to understand an artistic drawing, it is sometimes necessary an artist. Artists often take a subtle or abstract approach in communicating through their drawings. This gives rise to the various interpretation often associated with artistic drawings.

 

Technical Drawings

The technical drawing, on the other hand, is not subtle or abstract. It does not require an understanding its creator only an understanding of technical drawings.

A technical drawings is a means of clearly and concisely communicating all of the information necessary to transform an idea or a concept into reality. Therefore a technical drawing often contains more than just  a graphic representation of its subject. It also contains dimensions, notes. And specifications.

The mark of a good technical drawing is that it contains all of the information need by individuals for converting the idea or concept into realty. The conversion process my involve manufacturing, assembly, construction, or fabrication. Regardless of the process involved , a good technical drawing allows the conversion proceed without having to ask designers or drafters for additional information or clarification.

Figures 1-1 and 1-2 contain samples of technical mechanical drawings which are used as guides by the people involved in various phases manufacturing the represented parts. Notice that the drawings contain a graphic representation of the part, dimensions. Material specifications, and notes.

 

Illustrations or Renderings

Illustrations or renderings are sometimes referred as a third type of drawing because they are not completely technical, neither are they completely artistic. They combine elements of both, as shown in figures 3-1 , 4-1, 5-1, and 6-1. They are technical in that they are drawn with mechanical instruments or on a computer-aided drafting system. And they contain degree of technical information . however , they also artistic in that they attempt to convey a mood. An attitude, a status or other abstract, nontechnical feelings.

 

Type of Technical Drawings

Technical drawings are based on fundamental plcipes  of projection. A projection is a drawing or representation of an entity on an imaginary plan or planes. This project plan serves the same purpose in technical drawing is served by the movie screen in a theater.

As can be seen in figure 7-1, a projection involves four components : 1) the actual object that the drawing or project represents. 2) the eye of the viewer looking at the object. 3) the imaginary projection plane ( the viewer’s drawing paper or the graphics display in a computer-aided drafting system). And 4) imaginary lines of sight called projectors.

Two broad types of projection , and perspective (converging) projection.

 

Parallel Projection

Parallel projection is subdivided into the fallowing metric projection : orthographic , oblique, and axonometric projections.

Orthographic projections are drawn as multiview drawings which show flat representations of principal views of the subject. Figure 1-8. Oblique projections actually show the depth of the subject, and are of two varieties: cabinet (half scale) or cavalier (full scale) projections. Figures 1-9 and 1-10. Axonometric projection are three dimensional  drawings. And are of three different varieties: isometric, diametric, and trimetric. Figures 1-11, 1-12, and 1-13.

 

Perspective Projection

Perspective projection are drawings which attempt to replicate what the human eye actually sees when attempt to views an object. That is why the projectors in a perspective drawing converge. There are three types of perspective projections: one-point, two-point , and three-point projections. Figures 1-14, 1-15 , and 1-16.

 

Purpose of Technical Drawings

To appreciate the need for technical drawings. One must understand the design process. The design process is on orderly. Systematic procedure used in accomplishing a needed design.

Any product that is to be manufactured. Fabricated assembled, constructed  built or subjected o any other type of conversion process must be designed before it can be manufactured. A printed circuit board must be designed be for it can be fabricated.

 

The Design Process

The design process is an organized, step-by-step procedure in which mathematical and scientific principles. Coupled with experience, are brought to bear in order to solve a problem or meet a need. The design process has five steps. Traditionally, these steps have been 1)identification  of the problem or a need.2)development of initial for solving the problem, 3) selection of a proposed solution, 4) development and testing of models or prototypes,         5) developing working drawing. Figure 1-17.

The age of computers has altered the design process slightly for computers which have converted to computer-aided design and drafting. For these companies. The expensive, time-consuming fourth step in the design process– the making and testing of actual models or prototype – has been substantially altered. Figure 1-18. This fourth step has been replaced with three-dimensional computer models which can be quickly and easily produced on a CAD system using the data base built-up during the first three phases of the design process. Figure 1-19.

Whether in the traditional design process or the hore  modern computer version, in either case, working drawings are an integral part of the design process form start to finish.

The purpose of technical drawings is to document  the design process. Creating technical drawings to support the design process is called drawing people. Figure 1-16. Three-point perspective projection who do drafting are known as “draftsman” or “ draughtsman” are no longer used.

In the first step of the design process, technical drawings are used to help clarify the problem or the need. The drawings may be old ones on file or they may be new ones created for the purpose of clarification. In the second step, technical drawings- are used to document the various ideas  and  concepts formed. In the third step, technical drawings again, usually  preliminary drawings – are used to communicate the purposed solution.

If the traditional fourth step in the design process is being used, preliminary drawings and sketches form the first three steps  will be used as guldes in constructing models or prototypes for testing. If the more modern fourth step is begin used. The data base built-up documentation of the first three steps can be used in developing three-dimensional computer models. In both cases, the final step is the development of complete working drawing for guiding individuals  involved in the conversion process. Figure1-20is a working drawing documenting the design of a simple mechanical par. The drawing was produced on a cad system.

 

Application of Technical Drawings

Technical drawings are used many different applications. They are needed in any setting which involves design, and in any subsequent form of conversion process. The most common applications of technical drawings can be found in the fields of manufacturing, engineering, architecture and construction, and all of their various related fields.

Architects use technical drawings to document their designs of residential , commercial , and industrial buildings. Figures 1-22 and 1-23. Structural, electrical, and mechanical heating, ventilating, air conditioning (HAVAC) and plumbing engineers who work with architects also us technical drawings to document those aspects of the design for which they are responsible. Figures 1-24, 1-25, and 1-26.

Surveyors and civil engineers use technical drawings to document such work as the layout of a new subdivision, or the marking-off of the boundaries for a piece of property. Figure 1-27. Contractors  and construction personnel use technical drawings as their blueprints in converting architectural and engineering designs into reality. Figures 1-28 and 1-29.

 

نوشته شده در تاریخ دوشنبه 3 بهمن 1390    | توسط: مدیر وبلاگ    | طبقه بندی: زبان تخصصی، آموزش نقشه کشی،     |
نظرات()