İki Kademeli Helisel Dişli Kutusunun Bilgisayar Destekli Parametrik Tasarımı

Abstract

Bu çalışmada iki kademeli helisel dişli kutusunun bilgisayar yardımıyla boyutlandırılması ve yine bilgisayar yardımıyla teknik resimlerinin çizdirilmesi gerçekleştirilmiştir. Bu amaçla bir çeşit yapay zeka programı olan Lisp programlama dilinin AutoCAD programına uyarlanmış hali olan Autolisp programlama dili kullanılmıştır. Yapılan çalışma dört bölümden meydana gelmektedir. Birinci bölümde, konunun önemi ve amacı ile diğer bölümler arasındaki ilişki verilmiştir, ikinci bölümde iki kademeli helisel dişli kutusunun boyutlandırılma esasları anlatılmıştır. Üçüncü bölümde programlama da kullanılacak olan AutoLisp programlama dilinin temel özellikleri ve fonksiyonları anlatıldıktan sonra, son bölüm olan dördüncü bölümde boyutlandırmayı yapan ve teknik resimleri çizen programın içeriği ve çalışma şekli hakkında bilgi verilmiştir. İki kademeli helisel dişli kutusunun boyutlandırılmasına motorun gücü,giriş ve çıkış devir sayısı, dişlilerin yerleştirilme biçimi, dişli mekanizmasının çeşiti gibi başlangıçta bilinmesi gerekenlerin bilindiği kabulüyle başlanmıştır. Boyutlandırma ve çizim için; hesap, ongor, ustgor, yangor, baslik, gövde, mil,disli ve kapak olmak üzere dokuz adet program dosyası hazırlanmıştır. Bu dokuz dosyadan sadece hesap boyutlandırma amaçlı olup diğerleri çizim amaçlıdır. Çİ2İrnin yapılabilmesi için boyutlandırmanın yapılmış olması gerektiğinden öncelikle boyutlandırma dosyasının çalıştırılması ve sorulan tüm soruların cevaplandırılması gerekir. Çizim dosyalan ancak bundan sonra çalıştırılabilir. Boyutlandırma yapan hesap isimli dosyanın sonuna, boyutlandırma ile direkt olarak ilgisi olmamasına rağmen özellikle bu konuda yapılabilecek çalışmalara yardımcı olacağına inanıldığı için dişli kutusunun ağırlığını hesaplayan bir alt program da eklenmiştir. Boyutlandırma ve çizim yapan dosyaların çalıştırılabilmesi için tüm dosyaların AutoCAD ortamına yüklenmesi ve öncelikle boyutlandırmayı yapan hesap isimli dosyanın çalıştırılması yeterlidir. Hesap isimli dosya çalıştırıldıktan ve sorulan tüm sorulara cevap verildikten sonra istenilen herhangi bir çizim dosyası çalıştırılabilir.

In this study, Computer Aided Design of double reduction helical gear box and its technical drawings are investigated. For this purpose, a kind of artificial intelligence program named Autolisp that is adapted to the subprogram of Lisp called AutoCAD is used. This study is explained under four major topics. In the first part, the importance and the purpose of the concept besides the relations with other parts are given in this part. In the second part design criteria of double reduction helical gear box are explained. Introducing basic properties and the functions of Autolisp programming language used for programming, in the third part, in the last part information about the content and working conditions of the program used for design and technical drawings is given. It's started to design of double reduction helical gear box assuming that, in the beginning,. Value of incoming power. Total reduction ratio. Location of gears. Type of gears are known. In the light of this assumption all calculations required to design is explained in their order in the part two. Sequence followed at the design is as follows, of module calculation of reduction ratio for each stage calculation of torque at the shafts selection of gear materials and the other factors used for calculations calculation of module according to strength control of the calculated module according to surface pressure calculation of gear dimension selection of shaft materials calculation of forces acting on the shaft calculation of diameters of shafts control these diameters according to control calculations calculation of bearing calculation of wedges control these wedges according to control criterion calculations for temperature control XIV Sugested values for similar processes are given by tables when required during the explanations of calculations. All of these are taken into consideration at prepaired program- In the part three, basic characteristics and the functions of Autolisp used in programming are explained. In this explanation, functions are grouped according to their useage and they are described under these group titles. These groups titles are as follows,. Arithmetic operation functions. Conditional functions. List Manipulation functions. Geometric utilities functions. User input functions. Display control functions. Selection sets functions. The other functions And also format of each function is included in this part. AutoLISP, an implementation of the LISP programming language, is an integral part of the AutoCAD package. AutoLISP lets users and AutoCAD developers write macro programs and functions in a powerful high-level language that is well suited to graphics applications. AutoLISP supports the following data types; Symbols Lists Strings Integers Real numbers File descriptors AutoCAD entity names AutoCAD selection sets Subrs (built-in functions) External subrs AutoLISP input can take several forms. It can be entered from the keyboard at the AutoCAD prompt line, read from an ASCII file, or read from a string variable. In all case, these conventions must be followed;. Symbol names can consist of any sequence of printable characters except ().'";. The following characters terminate a symbol name or numeric constant ( ) ' " ; (space) (end of line). Expression can span multiple lines. Multiple spaces between symbols are equivalent to a single space XV . Symbol and functions names (subrs) are not case-sensitive in AutoLISP; they can be entered uppercase or lowercase. Integer constants can begin with an optional (+) or (-) character. Their range is -2.147.483.648 to 2.147.483.647. Real constants can begin with an optional positive (+) or negative (-) character and consist of one or more numeric digits, followed by a decimal point, followed by one or more numeric digits (i.e.,.5 is not recognized as a real ; 0.5 is correct). Real constants can be expressed in scientific notation, which has an optional (E or e) followed by the exponent of the number (i.e., 0.00005 is the same as 5 E -5). Literal strings are sequences of characters surrounded by double quotes. Within quoted strings the backslash (\) character allows control characters to be included. These codes are folow, - Code W which is meaning \ character - Code\e which is meaning escape character - Code \n which is meaning newline character - Code\r which is meaning return character - Code\t which is meaning tab character - Code\xx which is meaning character whose octal code is xx. Using comments in program code is very important. Comments are useful to both the programmer and future users who may need to revise a program to suit their needs. A comment in AutoLISP is anything on a line that follows a semicolon (;). Comments begin with a semicolon and continue through the end of the line. Some of the uses for comments are the following; give a title, authorship and creation date, provide instructions on using a routine, make explanatory notes throughout the body of a routine, make notes to yourself during debugging and allow for characters that provide visual aesthetics. All AutoLISP expressions have to be this form (function name [ arguments] ). Each expression begins with a left paranthesis and consist of a function name and optional list of arguments to that function. The expression then ends with a right parenthesis. Every expression returns a value that can be used by a surrounding expression, if there is no surrounding expression, AutoLISP returns the value of AutoCAD. If an incorrect expression is entered or read from a file, AutoLISP might display the following prompt n>, where n is an integer indicating how many levels of left parentheses remain unclosed. The AutoLISP files are saved with an extension of.lsp and loaded, using the AutoLISP load function or include them in an acad.lsp file to be loaded automatically each time AutoCAD is started. Loading a.lsp file causes evaluation of its expression. Most commonly a.lsp file uses the defun function to store groups of functions in the computer's memory for later execution. XVI If a function is defined with a name of the form c:xyz, it can be issued at the AutoCAD prompt line in the same manner as a built-in AutoCAD command. AutoLISP provides various funtions for examining the drawing currently loaded, modifying it, interacting with the AutoCAD user, and so on. It introduces the functions, describes how they can be used in conjunction with other function, and provides code examples of their use. For specific details on calling a particular function, refer to the third part. The most general of the AutoLISP functions that acsess AutoCAD is command. This function sends an AutoCAD command along with other related information directly to the AutoCAD command, prompt. All symbols, user-defined functions and the standart functions which explains third part this guide describes are stored in computer's memory for the duration of the AutoCAD editing session only. When AutoLISP starts up, it acquires two large areas of memory for itself. The first, called the heap, is the area where all functions and symbols are stored; the more symbol and functions are defined, the more heap space is used. The second area, called the stack, holds function arguments and partial results; the deeper functions, the more stack space is used. Using the alloc and expand functions to manually control symbols and string space allocation and so increase the efficiency of applications. By using these expressions at the beginning of acad.lsp file, it can be preallocate the symbols and also reverse some string space. This can reduce the number of garbage collections, improving the run-time efficiency of applications. The mem function (mem) displays the current state of AutoLISP' s memory, and returns nill function. Using the functions displays Nodes, Free Nodes, Segments, Allocate and Collections. Nodes is the total number of nodes (symbols) allocated so far. Free Nodes is the number of nodes currently on the free list placed there by a garbage collection. Segments is the number of node segment allocated. Allocated is the current segment size. Colections is a count of garbage collections. In the fourth part, the given informations up to now are combined. Procedures of the design using Autolisp program and the technical drawings programs;. hesap. ongor. ustgor. yangor. baslik. govde. mil. disli. kapak XVU which are prepaired are explained. For design and drawings, nine files which are prepaired. Hesap file performs design calculations, ongor draws front view of assembly, ustgor draws top view of assembly, yangor draws side view of assembly, baslik draws letterhead of assembly, govde draws manufacturing drawing of the frame, mil draws manufacturing drawing of the shaft, disli draws manufacturing drawing of the gear, kapak draws manufacturing drawing of the cover. As it can be seen that among nine files, only hesap file is used for design, the others are used for drawings. Since the design has to be done in order to perform drawings, first of all desing file called hesap must be run then the drawing files is required to be executed. Otherwise drawing files will not execute. It can be understood that hesap file that performs the design generates the information for drawing files and this file has to be run beforehand. In order to run the Autolisp files, it is enough to be loaded to AutoCAD enviroment. The end of this part sequence of operation of prepaired program which performs design calculation is added. In addition a file which calculates the weight of the double reduction helical gear box is added to the end of the hesap file which performs the design. The file is not directly related to the design, but it can be used at the future studies. The file which calculates the weight of the double reduction helical gear box calculates total weight of;. gears. shafts. bearings. covers. bodies The file neglects calculations of total weight of smaller units such as gasket and felt. Main process of the file that performs design is based on designing system by asking questions and evaluating the answers. For the wrong answers these are given by the user willingly or unwillingly (i.e. efficiency is greater than one) program refuses the answer and asks the question again. Drawing files are the files that can draw by using the informations from the design files. Those files are formed by defining approximately 4000 nodes. Drawing are being done by using main commandAutocad is given by these files. In these files over 4000 nodes are defined that is used by Autocad. In this study, Computer Aided Design (CAD) is investigated for the combination of Computer Aided Design and Computer Aided Manufacture (CAM). That's why specially the study bases for the Computer Aided Manufacture of double reduction helical gear box are drawn by prepaired program files.