93033 - Technical Drawing and CAD

Learning outcomes

The student is able to read and understand technical drawings according to international normatives and exploiting a CAD (Computer Aided Design) tool. Furthermore the student is able to make and manage both 3D modeling and 2D drafting to correctly communicate technical information, as functions, shapes and productive planning on machineries in industrial level.

Course contents

ELEMENTARY GEOMETRIC CONSTRUCTION
Bisection of a segment, of an arc, of an angle. Perpendicular to a segment (to a line) from an assigned point: external, belonging to it (central or end). Parallel to a given line (at a given distance, for a given external point). Operations related to angles. Trisection of the right angle and the flat angle. Division of a segment in equal parts. Tangents to a circumference from an external or belonging point. Radius of given radius tangent to a straight line in a point. Internal and external tangents to two circles. Circumference for three points, straight lines and circumferences with arcs of assigned radius. Regular polygons: triangle, square, pentagon, hexagon and octagon with assigned side or circumscribed circumference. Construction of a polygon with any number of sides note the circumscribed side or circumference. Flat curves (ellipse, parabola, hyperbola, oval, ovolo, involute of circumference). Study and comparison of the SNAPPING and OBJECT SNAPPING systems present in the CAD system.

THE ORTHOGONAL PROJECTION METHOD
Representation by orthogonal projection on two orthogonal planes of points, lines, planes. Conditions of belonging of point and line, line and plane, point and plane. Conditions of coplanarity, incidence and parallelism between lines; of parallelism between planes. The third projection plane: determination of the third projection of points, lines, planes, curves. Orthogonal projection of plane and solid figures. Criteria relating to the identification and representation of lines in sight and not.

TRUE FORM OF FLAT SURFACES
Generality. Rollover method. Point reversals, straight lines, segments, plane figures lying on planes perpendicular to the main projection planes.

Geometric primitives in MODEL SPACE and PAPER SPACE.

ASSONOMETRIC PROJECTIONS OBLIQUE, ORTHOGONAL AND PROSPECTS
Reduction factors. Unified oblique axonometry (cavaliera; UNI 4819). Parallel orthogonal perspective or orthogonal axonometry. Unified isometric axonometry (UNI 4819). Axonometric representation of flat surfaces, prisms, pyramids; exact and approximate representations of circumferences, curves and solids of revolution. The concept of homography and stereography.

SECTIONS
Purpose of the sections: ideal section plan. Flat sections of prisms and pyramids. Sections of revolution solids (cylinder, cone, sphere, torus). Determination of the contour lines of the sections: method of generating lines and method of auxiliary section planes. Solids obtained through section planes (truncated pyramid, cone, oblique cylinder, etc ...). Use of the PATTERN to obtain the backgrounds in the CAD system. SOLID CONCEPTIONS
Generality. Compenetration of prisms and pyramids. Particular uses of auxiliary section plans. Determination of the intersection line relative to the interpenetration of solids of revolution: method of generatrixes, method of auxiliary section planes, method of auxiliary spheres.

Dimensioning
General criteria, dimensioning and reference lines, arrangement and reading of quotas. Dimensioning systems (in series, in parallel, with overlapping dimensions, combined dimensioning, in coordinates, in polar coordinates). Particular dimensioning conventions (solids of revolution, circles, spherical surfaces, squares, bevels and roundings, elements regularly or irregularly arranged). Criteria for choosing the reference elements and general rules for a correct dimensioning.
Use of DIMENSION commands and their setting for a correct drawing of the drawing.

CONNECTIONS for FRICTION and for OBSTACLE
Threaded connections: definition of the main parameters; types, construction and representation of threads. Shaft-hub connections: keys, keyways,, grooved profiles, snap rings, etc.

DIMENSIONAL TOLERANCES
Nominal dimensions and dimensions with tolerance; Fixed gauges and differential gauges; Width, positions and deviations of the tolerance zone; Base shaft and base hole fits;

CAD TOOLS                                                                    Architecture of a CAD (Computer Aided Design) system. Hardware: computer, dynamic memory (RAM), mass memory (hard disk), flexible disks, CD-ROM. Data input: keyboard, mouse, digitizing tablets, scanner. Data output: vector and raster-scan display devices, hard-copy devices (plotters, dot-matrix printers, ink-jet printers, lasers). Software: interface with the operator, definition and elaboration of the model, image generation (rendering), database management, applications, utilities. Advantages and limits of CAD.

RASTER AND VECTORIAL GRAPHICS

Notes on raster and vector graphics with particular attention to use in CAD systems.

USE OF A CAD SYSTEM
The graphic primitives, initial design settings, data entry mode, object selection mode, object modification commands, display possibilities, support for pointing, layer use, block usage, dimensioning of a drawing, texts, headings and squaring, raster images, backgrounds, use of paper space, problems concerning printing, simple graphic primitives, complex graphic primitives, drawing of a relief, blocks with attributes.

PRINCIPLES OF 3D CAD SYSTEM OPERATION                                Coordinate systems and reference systems

· Coordinate systems:
· Cartesian coordinates
· Cylindrical coordinates
· Spherical or Polar coordinates
· Homogeneous coordinates
· Reference systems
· Local
· Global
· Of the observer
· Of view Representation on video of graphic primitives and notes on classical algorithms.

ELEMENTARY GEOMETRIC UNITS
Methods of representation of the main elementary geometric units.
Transformations:
· Translations
· Rotations
· Scale transformations
· Symmetry and Reflection

Readings/Bibliography

CHIRONE, TORNINCASA, Disegno Tecnico Industriale, ed. Il Capitello, Torino.

CONTI, Disegno tecnologico, vol. 1, 2, ed. Pitagora, Bologna.

SOBRERO, Corso di Disegno, solo vol. 1, ed. Pitagora, Bologna.
FILIPPI, Disegno di Macchine, vol. 1, 2, ed. Hoepli, Milano.
Mortenson, Modelli geometrici in computer graphics, McGraw-Hill.

Teaching methods

The course consists of a theoretical and practical part, taught in unified classroom sessions, and a portion of CAD exercises taught in the lab.

The hand-guided exercises will be performed in the classroom, while the computer-assisted exercises will be performed in the lab.

The instructor will perform some of the exercises on the blackboard and some on a projector.

Students must complete the assigned exercises and, if necessary, any exercises indicated for independent study or as optional.

An educational license for the software is available for installation on your own laptop. Using a laptop in the lab is not recommended.

Assessment methods

The exam consists of:

1) a 30-minute multiple-choice computer-aided test ("Part 1") covering topics covered during the course;

2) a 90-minute assembly extraction test ("Part 2"), which involves 3D computer modeling and the "construction drawing" of the component;

3) a final interview ("Part 3") that will address the issues addressed in the written part, review the models and drawings created and/or assigned during the course, and ask one or more theory questions.

Passing the initial test (minimum score required based on the difficulty of the test) grants admission to the written exam.

Part 1 and Part 2 will be held consecutively at the same workstation (PC) in the computer lab.

Part 3 may be scheduled after the written exam or on a different date (notified at the end of the written exam).

Registration for the exam is done through AlmaEsami [http://almaesami.unibo.it/]

 

Students with specific learning disorders (SLD) or temporary/permanent disabilities: We recommend contacting the University Office responsible for support services in a timely manner (https://site.unibo.it/studenti-con-disabilita-e-dsa/it) [https://site.unibo.it/studenti-con-disabilita-e-dsa/it):]). The office will evaluate the students' needs and, where appropriate, propose possible accommodations. These must in any case be submitted for approval at least 15 days in advance to the course instructor, who will assess their suitability also in relation to the learning objectives of the course.

Teaching tools

Frontal lectures.

The course involves the use of computers in the computer lab equipped with a 3D CAD system for parametric solid modeling and automatic drawing.

Office hours

See the website of Giampiero Donnici

See the website of Fabio Grandi