Lecture #4 MULTIVIEW PROJECTION RES 112E COMPUTER AIDED TECHNICAL DRAWING ITU

Transcription

1 Lecture #4 MULTIVIEW PROJECTION

2 This week You will learn multi-view projection. The steps to follow are: Projections (ISO-E & ISO-A) Multi-view drawings Views (Basic,Auxiliary, Detailed etc.) Sketching 2-D Geometry Assignment # 3

3 Principles ORTHOGRAPHIC PROJECTION

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5 Projections Multi-view projection (Orthographic projections): are drawn as multi view drawings, which show flat representations of principal views of the object. Parallel Projection is a type of projection where the line of sight or projectors are parallel and are perpendicular to the picture planes. Oblique Projections: actually show the full size of one view. Axonometric Projections: are three-dimensional drawings, and are of three different varieties: Isometric, Dimetric and Trimetric. Perspective projections are drawings which attempt to replicate what the human eye actually sees when it views an object.

6 The attributes of projection methods

7 What is orthographic? Orthographic projection is a method of producing a number of separate two-dimensional inter-related views, which are mutually at right angles to each other. Using this projection, even the most complex shape can be fully described. the plane upon which the frontal view is projected the plane upon which the top view is projected the plane upon which the side view is projected

8 History of orthographic The way of communicating ideas that everybody understood was a problem that faced Gaspard Monge (as an Engineer in the French Military). He devised a system that could be used to communicate an object to anyone across the world. This system is called Orthographic Projection and was quickly adopted by army engineers.

9 Orthographic Projections Orthographic projections are drawings where the projectors, the observer or station point remain parallel to each other and perpendicular to the plane of projection. Orthographic projections are further subdivided into axonomet ric projections and multi-view projections. Effective in technical representation of objects.

10 Projection systems

11 Orthographic projection

12 Orthographic projection

13 Projection Symbols

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15 Miter line Orthographic Projection utilizes a Miter Line drawn at 45 degrees which enables information to be projected from the top view to the side view, and from the side view to the top view.

16 Principles MUTLIVIEW DRAWING

17 What is multiview? Another name for orthographic projection is multiview drawing. Multi-view (multiplanar) projection is a method by which the exact shape of an object can be represented by two or more separate views produced on projection planes that are at right angles to each other. Involves visualization and implementation oability to see an object clearly in the mind s eye. oprocess (steps) of drawing the object

18 Multiview drawing omultiview drawing is classified as a parallel projection technique, because the lines of sight used to view the object are parallel oa system that allows you to make a two-dimensional drawingof a three-dimensional object. othe images are called views. TOP BACK L.SIDE FRONT R.SIDE BOTTOM

19 Basic views There are 9 different types of views used for engineering drawings, namely Front view Top view Bottom view Rear view Left-side view Right-side view Auxiliary view Section view Detailed view

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21 Alphabet of Lines

22 Linetypes Center Lines You will draw the centerlines for the circle. Center lines for holes must be included in all views. A centermark and four lines extending beyond the four quadrant points are used. The centerline is used to: o Show the axis of symmetry of a feature or part o Indicate a path of motion o Show the location for bolt circles or other circular patterns

23 Linetypes Hidden Lines You should follow at least three general practices when drawing hidden lines to help prevent confusion and to make the drawing easier to read. o clearly show intersections using intersecting line segments o clearly show corners, using intersecting line segments o leave a noticeable gap between aligned continuous lines and hidden lines

24 Adjusting linteype scale LTSCALE determines the relative length of dashes in linetypes such as hidden and center lines. Setting a linetype scale ensures that the lines you draw are represented properly on the screen and when the drawing is plotted. Command : LTSCALE Enter new linetype scale factor <1.000> : 0.5 Regenerating model. Command :

25 Linetypes Width of slot projected into top view

26 Line Precedence Different types of lines often align with each other within the same view. The rule is that continuous lines take precedence over hidden lines, and hidden lines take precedence over centerlines. If you show the short end segments were a centerline would extend, be sure to leave a gap.

27 The order of precedence of lines Visible object lines Hidden lines Center line or cutting plane line Break lines Dimension and extension lines Crosshatch / section lines

28 Line Precedence Continuous line over a hidden line Hidden line over a centerline Continuous line over a hidden line

29 The following week You will learn creating section view. The steps to follow are: Cutting plane Kind ofsectional views (full, half, etc.) Section line symbols Conventional practice Assembly sections Creatingsection viewsinautocad Assignment # 4

30 Team Meeting DURATION 1 HOUR

31 Library web site :

32 TSE web site :

33 TPE web site :

34 European Patent Office web site :

35 Meeting minute

36 Assignment #3 Page Figure You will sketch and complete views Submit the assignment on time Upload file into NINOVA