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Computer Aided Machine Drawing Computer Aided Machine Drawing Instructor: Mohamed Abdou Mahran Kasem, Ph.D. Aerospace Engineering Department Cairo University Contact details Email: [email protected] Office hours: Monday, Wednesday Site link: https://scholar.cu.edu.eg/?q=mohamedabdou/classes Course details Textbooks: K.L. Narayana, P. Kannaiah, K. Venketa Reddy - Machine Drawing Leu, NX for engineering design Grades: 1 lecture/2Weeks – 2 tutorials/week Lecture Attendance 5 % Lab Progress 10 % HWs 10 % Final Project and oral exam 15 % Final Exam 60 % Why Machine Drawing Why do you study Machine Drawing ? CAD Model Finite Element Mesh Learning Outcomes • Understand the principals of drawing • Study the methods of drawing mechanical parts such as bolts, Screw jack, and Bearing ejecting clamp • Know the basic of computer aided design, Fitting, Tolerances, Drafting, surface roughness, and assembly • Develop drawings for mechanical parts such as bolts, Screw jack, and Bearing ejecting clamp. • Perform part drawing and assembly • Build CAD models for mechanical parts, sketching, drafting, and assembly • Design using Siemens NX Introduction • Machine drawing serves as a graphic language which any trained person can visualize the required object. • Engineering drawing is the universal language of all engineers. • Engineering drawing has its origin sometime in 500 BC in the regime of King Pharos of Egypt when symbols were used to convey the ideas among people. Classification of Drawings 1. Machine Drawing It is pertaining to machine parts or components. It is presented through a number of orthographic views, so that the size and shape of the component is fully understood. Part drawings and assembly drawings belong to machine drawing. Classification of Drawings 2. Production drawing A production drawing, referred to as working drawing, should furnish all the dimensions, limits and special finishing processes such as heat treatment, surface finish,etc., to guide the craftsman on the shop floor in producing the component. Principles of Drawing • Engineering drawings are to be prepared on standard size drawing sheets. • To provide the correct information about the drawings to all the people concerned, the drawings must be prepared, following certain standard practices, as recommended by Bureau of Indian Standards (BIS) Principles of Drawing – Drawing sheet • Engineering drawings are prepared on drawing sheets of standard sizes. • The use of standard size sheet, saves paper and facilitates convenient storage of drawings. Principles of Drawing – Drawing sheet Where X and Y are the sides of the sheet. For a reference size A0 having a surface area of 1 , X = 841 mm and Y = 1189 mm. The successive format sizes are obtained either by halving along the length or doubling along the width, the areas being in the ratio 1:2 Principles of Drawing – Drawing sheet • The title block is at the bottom right hand corner. • The title block can have a maximum length of 170 mm, providing the following information: (i) Title of the drawing (ii) Sheet number (iii) Scale (iv) Symbol, denoting the method of projection (v) Name of the firm (vi) Initials of staff drawn, checked and approved. Principles of Drawing – Drawing sheet Principles of Drawing – Drawing sheet Borders and frames Principles of Drawing – Drawing sheet Scale is the ratio of the linear dimension of an element of an object as represented in the drawing, to the real linear dimension of the same element of the object itself Principles of Drawing – Drawing sheet Recommended scales Principles of Drawing – Drawing sheet Types of lines and its applications Principles of Drawing – Drawing sheet Types of lines and its applications Principles of Drawing – Drawing sheet Types of lines and its applications The thickness of lines should be chosen according to the size and type of the drawing from the following range: Principles of Drawing – Drawing sheet Leader lines: A leader is a line referring to a feature (dimension, object, outline, etc.). Leader lines should terminate Principles of Drawing – Drawing sheet Lettering Principles of Drawing – Drawing sheet Notes: Notes should always be written horizontally in capital letters and begin above the leader line and may end below also. Computer Aided Design – CAD engineers are now using Computer Aided Design (CAD), Computer Aided Manufacturing (CAM) and Computer Aided Engineering (CAE) systems to automate their design and production processes. Computer Aided Design – CAD • CAD is technology concerned with using computer systems to assist in the creation, modification, analysis, and optimization of a design. • Any computer program that embodies computer graphics and an application program facilitating engineering functions in design process can be classified as CAD software. • The greatest benefits of CAD systems are that they can save considerable time and reduce errors caused by otherwise having to redefine the geometry of the design from scratch every time it is needed. Computer Aided Engineering – CAE • CAE technology uses a computer system to analyze the CAD-created products, allowing designers to simulate and study how the product will behave so that the design can be refined and optimized. • CAE tools are available for a number of different types of analyses such as kinematic analysis, stress analysis, and dynamic analysis. • One of the most popular methods of analyses is using a Finite Element Method (FEM). • This approach can be used to determine stress, deformation, heat transfer, magnetic field distribution, fluid flow, and other continuous field problems that are often too tough to solve with any other approach Computer Aided Manufacturing – CAM • CAM technology involves computer systems that plan, manage, and control the manufacturing operations through computer interface with the plant’s production resources • One of the most important areas of CAM is numerical control (NC). This is the technique of using programmed instructions to control a machine tool, which cuts, mills, grinds, punches or turns raw stock into a finished part. • Another significant CAM function is in the programming of robots Product Realization Process • The product realization process can be roughly divided into two phases; design and manufacturing. • The design process starts with identification of new customer needs and design variables to be improved, which are identified by the marketing personnel. • Once the relevant design information is gathered, design specifications are formulated • A feasibility study is conducted with relevant design information and detailed design and analyses are performed. • The detailed design includes design conceptualization, prospective product drawings, sketches and geometric modeling. • Analysis includes stress analysis, interference checking, kinematics analysis, mass property calculations and tolerance analysis, and design optimization. Product Realization Process • The manufacturing process starts with the shop-floor activities beginning from production planning, which uses the design process drawings and ends with the actual product. • Process planning includes activities like production planning, material procurement, and machine selection. • Process planning includes planning for all the processes used in manufacturing of the product. • Parts that pass the quality control inspections are assembled functionally tested, packaged, labeled, and shipped to customers. Product Realization Process Chapter 5: Screwed Fasteners Screwed Fasteners • A machine element used for holding or joining two or more parts of a machine or structure is known as a fastener. • The process of joining the parts is called fastening. • The fasteners are of two types : permanent and removable (temporary). • Riveting and welding processes are used for fastening permanently. • Screwed fasteners such as bolts, and nuts in combination, machine screws, etc., and keys, cotters, couplings, etc., are used for fastening components that require frequent assembly and dissemble. Screwed Fasteners • Screwed fasteners occupy the most prominent place among the removable fasteners. • In general, screwed fasteners are used : (i) to hold parts together, (ii) to adjust parts with reference to each other, and (iii) to transmit power. Screw Thread Nomenclature A screw thread is obtained by cutting a continuous helical groove on a cylindrical surface (external thread). Screw Thread Nomenclature Screw Thread Nomenclature Screw Thread Nomenclature Screw Thread Nomenclature Representation of threads • The crests of threads are indicated by a continuous thick line and • the roots, by a continuous thin line. Representation of threads For hidden screw threads, the crests and roots are indicated by dotted lines. Representation of threads For threaded parts in section, hatching should be extended to the line defining the crest of the thread. Representation of threads In the view from side, the threaded roots are represented by a portion of a circle, drawn with a continuous thin line, of length approximately three-quarters of the circumference. Drawing hexagonal bolt head or nut Drawing hexagonal bolt head or nut Drawing hexagonal bolt head or nut Drawing hexagonal bolt head or nut Washers Drawing hexagonal bolt head or nut Drawing hexagonal bolt head or nut Drawing hexagonal bolt head or nut Locking arrangement for nuts Lock Nut Drawing hexagonal bolt head or nut Locking arrangement for nuts.
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