Helisel dişli çarkların autocad ortamında ADS ile interaktif tasarımı

Abstract

Herhangi bir üretim, ürün tasarımı ve ürün imalatı olmak üzere iki esas kademeden meydana gelmektedir. Ürün tasarımı veya kısaca tasarım herhangi bir teknik yapıtın ödevinin kesin olarak belirtilmesi, uygulanacak fiziksel ilkelerin saptanması, bu ilkeleri sağlayan elemanların seçimi, hesaplanması, bunların montaj ve parça resimlerinin hazırlanmasına kadar geçen tüm işlemleri kapsayan bir faaliyettir. Bu ifadeye göre tasarım: fikir oluşturma ve şekillendirme olmak üzere iki kademeden meydana gelmektedir. Günümüzde tüm bu işlemler Bilgisayar Destekli Tasarım (CAD) adını taşıyan bilgisayar programların yardımıyla yapılmaktadır. Sony ı Harda bilgisayarların gelişmesi ve buna bağlı olarak mühendislik alanında da CAD/CAM (Computer Aided Design / Computer Aided Manifacturing) konusunda büyük gelişmeler olmuştur. Artık mühendisler için oldukça önem arz eden tasarım işlemi, daha kısa sürelerde yapılabilmektedir. Bu çalışmada, bir helisel dişli çark çiftinin boyutlandırılması ve imalat resimlerinin çiziminin yapılması sağlanmıştır. Bu amaçla, C programlama dili kullanılarak AutoCAD ortamında ADS(AutoCAD Development System) dikkate alınarak bir bilgisayar programı hazırlanmıştır. Böylece CAD için tasarlanmış olan AutoCAD programına ek bir komut eklenmiş ve bunun sayesinde AutoCAD içinde interaktif olarak menüler yardımıyla helisel dişli çarklar için gerekli olan değerlerin girişi ve parametrelerin seçimi sağlanmıştır. Program, kullanıcının girmiş olduğu değerlere göre çeşitli faktörleri seçmekte, bunlara göre boyutlandırma hesabını yapmakta, modül ve buna bağlı boyutları çıkarmakta, dişli imalat tablosunu hazırlamakta, yüzey işaretlerini seçmekte, dişli toleranslarını belirlemekte ve bunlara bağlı olarak uygun ölçekte pinyon ve dişli çarkın ayrı ayrı imalat resimlerini çizmektedir. Ayrıca istenirse bulunan sonuçlar yazıcıdan da alınabilmektedir.

Industrial revolution and technological development witnessed at the beginning of this century. With the support of the electronic industry, facilitated significant improvement in computer technology, especially after the Second World War. Those developments in the computer technology have facilitated emerging of the new logic systems in design and manufacturing. In classical logic transformation of the idea to a product depends on experience and from, and necessitates expert personnel on its field. In this logic structure still adapted today, engineering calculation and production planning require intensive human efforts and usually cause excessive time loss and sometimes errors. Those factors, which increase the cost, prevents the idea from transformation to product in the real meaning and correctness. Computer Aided Design ( CAD ) and Computer Aided Manufacture ( CAM ) have been developed to create a dynamic environment in the transient period. From idea to product CAD/CAM have brought the flexibility and dynamism to the design which are missing at the classical logic application. While the computer used to be employed for carrying and the complex calculations at the beginning, today it is used for its drafting and designing capabilities as well as for those objects. CAD/CAM systems which include those properties have been tried to be developed. Nowadays the computer are known to be utilized in every phase of science, economics and industry. The modern computers have greatly developed as devices or carrying out mathematical calculations, basic logical operations and string data. One of the most important needs in engineering is to watch the evolution of a design and even to make various experiments on product, while it is being constructed (designed + manufactured). This need, especially, comes to light, while the product is first designed. For instance, when designing, a constructor should see the consideration in his mind, and IX test it, and use the data which come from the test to reconstruct the item. Thus the assembly will get nearer to optimum and be designed faster than the primitive way of designing would. Before computer technology has developed to succeed this, the process was being done by means of models and prototypes during the phases of construction. However, this way was rather expensive and time-consuming. So only the last prototype, whose design had been just completed, was manufactured in major productions such as motor production, car production. Therefore, the product was owning non-optimum characteristics and only the basic condition were being occupied. Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) is technology concerned with the use of degital computers to perform certain functions in design and production. This technology is moving in the direction of greater integration of design and manufacturing. Ultimately, CAD/CAM will provide the technology base for the computer- integrated factory of the future. Computer Aided Design (CAD) can be defined as the use of computer systems to assist the creation, modification, analysis or optimization of a design. The computer systems consist of the hardware and software to perform the specialized design functions. The CAD hardware typically includes the computer, one or more graphics display terminals, keyboards, and other peripheral equipment. The CAD software consists of the computer programs to implement computer graphics on the system plus application programs to facilitate the engineering functions of the user users. Examples of these application programs include stress-strain analysis of components, heat-transfer analysis, cost calculations, dynamic response of mechanisms and numerical control part programming. The collection of application programs will vary from one firm to other because their product lines, manufacturing processes, and customer wishes are different Computer Aided Design includes any type of design activity which makes use of the computer systems to develop, analyze, optimize or modify an engineering design. Modern CAD systems are based on interactive computers graphics. Interactive computer graphics denotes a user-oriented system in which the computer is employed to create, transform and display data in the form of pictures or symbols. The user in the computer graphics design system is the designer, who comminicates data and commands to CPU (centeral processing unit) of the computer through any of several input devices. Computer Aided Manufacturing (CAM) can define as the use of computer systems to plan, manage and control operations of a manufacturing plans through either direct or indirect computer interface with the plant's production resources. Computer Aided Design refers to any application of a computer to the solution of design problems. CAD is a technique in which the engineer and a computer work together as a team, by utilizing the best characteristics of each. CAD enables the engineer to test a design idea and to rapidly see its effect, the design idea can then be modified and reassessed. The process is repeated until a good design is achieved. A modern computer aided design system can be grouped into four functional areas;. Geometric Modelling: In computer aided design, geometric modelling is concerned with the computer compatible mathmatical description of the geometry of an object. The mathmatical description allows the image of the object to be displayed and manipulated on a graphic terminal through signals from the central processing unit of the computer aided design system. The software that provides geometric modelling capabilities must be designed for efficient use both by the computer and the human designer.. Engineering Analysis: This analysis may involve stress-strain calculation, heat transfer computations, or the use of differential equations to describe the dynamic behaviour of the system being designed. The computer can be used to aid in this analysis work. It is often necessary that specific programs be developed internally by the engineering analysis group to solve a particular design problem. In other situations, general purpose programs can be used to perform the engineering analysis.. Design Review and Evaluation: This step includes checking of the accuracy of the design. Other procedures for design review and evaluation are interference checking and kinematics.. Automated Draughting: This involves the creation of the hardcopy engineering drawings directly from the computer aided design database. Some computer aided systems have draughting packages that include automatic dimensioning, generation of crosshatched areas, scaling of the drawing and capability to develop sectional views and enlarged views of particular part details. In this study a computer program is developed for design of helical gears. The program does interactive design for helical gears in AutoCAD with ADS (AutoCAD Development System). Therefore a new command is added to the AutoCAD. The command operates the program. The command added to the AutoCAD is represented by "DISLI" and is put under "Asist" XI (pull-down menu of AutoCAD). To start the program first of all the AutoCAD program is started and "DISLI" command is selected from "Asist" pull-down menu or command line. The menues come on the screan one by one for entering variables or fixed values. The AutoCAD Development System (ADS) is a C-language programming environment for developing AutoCAD aplications. Like the standard C libraries, the ADS environment is defined by library and header files. These are available for nearly all platforms (machines ans operating systems) that currently support AutoCAD. ADS applications written and compiled under Release 11 can run under Release 12 if the platform (hardware and operating system) has not changed. The program have been written in C programming language. Because the last versions of the AutoCAD is supporting C programming language. Thus the AutoCAD gives programmers the ability to making new programs in AutoCAD. These programs join the AutoCAD as a new special features. So programmers can do new programmes for using flexible features of AutoCAD. The AutoCAD Development System (ADS) programming interface lets programmer high-level programming languages like C to customize AutoCAD. Programmer can run third-party ADS application programs or write his own. AutoLISP is generally more suitable for smaller, simple programming jobs; in addition, writing AutoLISP programs is often simpler than writing programs in higher level languages. In general, ADS is best suited to large, complex programming tasks or compute intensitive applications. The ADS interface consists of a library of functions that parallel AutoLISP functions. An ADS application is not written as a stand-alone program, but as a set of external subroutine functions that are loaded by, and called from, the AutoLISP interpreter. The program computes dimensions and drafts technical drawings of a pair of helical gears. After the program started, the menues come on the screen one by one for entering variables or constants values. The menues is programmed in ADS with using DCL(Dialog Conturol Language). So user can enter the values easily. For example, selecting of materials and quality is making with pull-down menues by user. For faulty entries the program gives different warnings. User can return back at any stage of the program. So the program provides more flexiblity. Results which is calculated by the program can taken from printer. At the end of the program drawings can be drafted technical drawings for gears according to result values. For drafting technical drawings, the program prepares the gears manufacturing tableau, calculates the values in this tableau, choices gear manufacturing tolerances from having been puting tolerance tableaus according to choicing tolerance space and choices surface quality according XII to gear quality. After that the program drafts technical drawings for first and second gear. if the gears dimentions is small, the program enlarges scale of picture or if the gears dimentions is large, the program makes small scale of picture. After the drafting finishes in computer, we can make drafting on printer, lazer printer or ploter. The program compiled in Borland C and programed according to AutoCAD R12. The programm can be used with AutoCAD R12 or foilowwig versions.