C 1 2013 engineering graphics

8/13/2019 C 1 2013 engineering graphics

1/38

8-Jan-14 1

ENGINEERING

GRAPHICSCourse No. 1


2/38

8-Jan-14 2

BIBLIOGRAFIE:

1. Petrescu L., s.a.GEOMETRIE DESCRIPTIVA SIGRFICINGINEREASC, Ed. BREN, Bucuresti, 1997.2. Petrescu L.ENGINEERING GRAPHICS,

Ed. BREN, Bucuresti, 2003.

3. Frederick E. Giesecke, Alva Mitchell s.a.TECHNICAL DRAWING, Mecmillan Publishing

Company, New York, 1986.4. Herbert W. YankeeENGINEERING GRAPHICS,PWS Engineering Publishers, Boston, 1985.

PETRESCU LIGIA confereniar doctor inginerDepartament

GRAFICINGINEREASC I DESIGN [email protected]

0742181465


3/38

8-Jan-14 3

The engineering thinkingandcreationcombines spatial

imagination, spatial situations

analysis and synthesis, with theengineering art and with an own

language of communication.


4/38

8-Jan-14 4

The representationof a real or an

imaginary object, of an idea thatexist in the mind of the engineer

or designer before becoming

reality, executed either on aclassical support (paper),or on amodern one (computers screen),

is realized in a graphic way.


5/38

8-Jan-14 5

Although different languages are

spoken throughout the World, auniversal language existed from

ancient times, the graphiclanguage. This natural,elementary mean of idea

communication is limitlessboth inspace and time.


6/38

8-Jan-14 6

The engineering graphicsis more

than a language, it is a wholeconception of space and of the

spatial object representation; it is

the solutions source of the spatialproblems and situations. Thats

why the eng ineer ing graphicsis

ascience.


7/38

8-Jan-14 7

The components of this science

are:

Descriptive geometry

Technical drawing Computer graphics(computer

aided drawing).


8/38

8-Jan-14 8

1.2.1 SHEETS (FORMATS) SR ISO 5457-94 (STAS 1-84). The support of the drawings isrectangular The sheet can be set vertically (Fig. 1.1-a), or

horizontally, meaning on the long side (Fig. 1.1-b), theirindexing being done as in the presented examples:

A(ab) A(ba)a). b).

Fig. 1.1

a

b

a

b


9/38

8-Jan-14 9

Preferred sheets Exceptional sheets

A0 841 1189 A02 1189 1682 A1 594 841 A13 841 1793 A2 420 594 A23 594 1261 A3 297 420 A24 594 1682 A4 210 297 A25 594 2102

Special sheets A35 420 1482A36 420 1783

A33 420 891 A37 420 2080 A34 420 1189 A46 297 1261 A43 297 630 A47 297 1471

A44 297 841 A48 297 1682 A45 297 1051 A49 297 1892


10/38

8-Jan-14 10

Fig. 1.2

20

10

Frame (border

line)

Title block

A(ba)

Zone for

binding in a

file

29

7


11/38

8-Jan-14 11

1.2.2 LINES STAS 103-84. Taking intoaccount the destination, there are two

thicknesses of lines that can be used: Thick or heavy

(thickness=b);

thin or fine (b/3or b/2).The line thicknessdepends on the dimensions and

complexity of the parts to be drawn, as well on thepurpose and size of the drawing. For b there aregiven the values: 0,18; 0,25; 0,35; 0,5; 0,7;1; 1,4; 2; 2,5; 3,5; 5.


12/38

8-Jan-14 12

The following types of lines are used as they

are needed:

continuous line

wavy line

zigzag line

dashed line

dash dot line

heavy open dash dot line two dots dash line


13/38

8-Jan-14 13

1.2.3 LETTERING SR ISO 3098/1-93 (STAS 186-86). The character of lines and the lettering gives

the drawing what is known as technique,a phaseof drafting which is too often neglected. The heightof the capitals or of the figures (numbers), defines

the size of the lettering by h: 2,5; 3,5; 5; 7; 10;

14; 20. It is permitted the use like slant the verticalwritingor the inclined writingat 75 degrees, and

like shape, a normal one(10/10xhthe height ofcapitals, and the thickness of the writing line

h/10), or a longed one(14/14x

h, the thickness ofthe writing line h/14).


14/38

8-Jan-14 14

1.2.4 TITLE BLOCK (INDICATOR) SR ISO 7200-94(STAS 282-87).

the identification zone : - the registration number oridentification of the

drawing;

- the name of the drawing;- the name of the legal owner

of the drawing.

the zone of supplementary information: - indicative;

- technical;- administrative.


15/38

8-Jan-14 15

TITLE BLOCK

Name Sign.

(Material)

(Drawing No.)

(Student

No.)

Student

Professor(Mass)

(Fac. YearGroup)121 E

(Scale)

1:1 (Drawing Name)(Date) 08.10.13

170

20 25 15 25 15

20

10

5

5

A(b x a)

Fig. 1.3


16/38

8-Jan-14 16

1.3 GENERAL NOTIONS ABOUTGRAPHIC REPRESENTATIONS

In the technical field the drawing is used asmeans of communication.

The shapeis best described through

projection, a procedure of getting an image byrays of observationor of sight. The direction ofthe rays can be parallel(when the observer islocated at an infinite distance from the object),

or conic(if the distance is a finite one), leadingto getparallel projections, orcentral(perspective) projections(Fig. 1.4 - a and b).


17/38

8-Jan-14 17

parallel projection central (perspective)

projection

a). b).

Fig. 1.4


18/38

8-Jan-14 18

SYSTEMS OF PROJECTIONS

A system of projection is compound by

four elements:

the observerseye;

the rays formed by lines of sight;the object to be projected;the plane of projection.

According to the space order of these four elements there

are two principal systems of projections:

European system (fig. 1.5)American system (fig. 1.6).

the observerseye

(at the )

the object

opaque

projection

plane

rays

Fig. 1.5

the observerseye(at the )

the object

transparent

projection

plane

rays

Fig. 1.6


19/38

8-Jan-14 19

The graphic representations used in technique,impose a very good knowledgeof elementarygeometry (plane and spatial),of the descriptivegeometry, and of the technical drawing.

Descriptive Geometryestablishes laws which areto enable the representation of spatial objects andof spatial situations. These laws (rules) are coming

directly from the elementary geometry. Technical drawingrelies on orthogonal(orthographic) projection, which supplies the bestconditions for describing shape of an object, and itis best fitted to make dimensioning, which is the

second function of a technical drawing.


20/38

8-Jan-14 20

1.3.2 COMPUTER GRAPHICS.Charles Babbage, anEnglish mathematician, developed the idea of a mechanicaldigital computer in the 1830s, and many of the principles

used in Babbages design are the basis of todayscomputers. The computer appears to be a mysteriousmachine, but it is nothing more than a toolthat justhappens to be a highly sophisticated electronic device. It iscapable of data storage, basic logical functions, and

mathematical calculations. Computer applications haveexpanded human capabilities to such an extent thatvirtually every type of business and industry utilizes acomputer, directly or indirectly.

The first demonstration with a computer, as a tool of

drawing and design, was made at the Institute ofTechnology of Massachusetts, in 1963, by Dr. Eng. IvanSutherland, with his system called Sketchpad.


21/38

8-Jan-14 21

The CAD(Computer Aided Design or Drawing)techniques, using specialized programs led to the

increase of the qualityof realism contained in thedrawing realized by means of computer.

The computer is able to do many things, veryquickly, but it is still an electronic equipment,

without brains, at least for the moment. It cannotthink and cannot do anything more or anything less

than what it was told to do. A CAD system is notcreative, but it can help a lot the user to become

more productive, earn time. The creator is theman with his so-called limit of his incompetence.


22/38

8-Jan-14 22

0x

b.

c.

x

0

[V]

[H]

[V]

[H]D ID II

D IVD IIID I

D II

D III

D IV

A

abc

B

C

[P]

a.

Fig. 2.1

THE SYSTEM OF PROJECTION

DIHEDRALS


23/38

8-Jan-14 23

TRIHEDRALS

x

z

y

[V]

[H]

[L]

0

T1

T2

T3

T4

T5

T6

T8

[H] [V]= - abscises axis[H] [L]= - depth axis[V] [L]= - quotas axis;

Fig. 2.2


24/38

8-Jan-14 24

x

z

y

[V]

[H]

[L]

0

A

a

xa

za

a

a

ya

T1

T2

T3

T4

T5

T6

T8

Fig. 2.4

abscisaxxAa

depthyyAa

quotazzAa

a

a

a

0"

0'

0

a horizontal projection

a - verticalprojection

a- lateral projection

T1 T2 T3 T4 T5 T6 T7 T8

x + + + + - - - -

y + - - + + - - +

z + + - - + + - -


25/38

8-Jan-14 25

x

z

y

[V]

[H]

[L]

0

a

xa

za

a

a

y1a

ya

y1

ais defined by the coordinates pear (x,y);a- is defined by the coordinates pear(x,z);a- is defined by the coordinates pear(y1,z);

Fig. 2.5

EPURA


26/38

8-Jan-14 26

za1

xa1

y1a1

a1a1

a1ya1

z

x 0

y1

y

a2

a2ya2

y1a2

za2

xa2

a2

z

x 0

y1

y

a. - A1(20, 40, 30) b. - A2(20, -40, 30)


27/38

8-Jan-14 27

c.A3(20, - 40, -30)

xa4

y1a4

a4ya4

z

x 0

y1

y

za4a4 a4

d.A4(20, 40, -30)

a3

a3ya3

za3a3

xa3

z

x 0

y1

y

y1a3


28/38

8-Jan-14 28

xa5

a5

a5

za5

y1a5

a5

ya5

z

x 0

y1

y

e.A5(-20, 40, 30)

ya6

a6za6

xa6

a6

a6

y1a6

z

x 0

y

y

f.A6(-20, - 40, 30)


29/38

8-Jan-14 29

g.A7(-20, - 40, -30)

Y

0

z

za7

xa7

y1a7

a7a7

a7ya7

y1

x

h.A8(-20, 40, -30)

Fig. 2.6

a8za8 a8

y1a8

ya8

z

x 0

y1

y

a8


30/38

8-Jan-14 30

x

z

y

[V]

[H]

[L]

0=k=m=n

H=h

K=k=k

v

M=m=m

l

L=l

h

v

N=n=n

V=v

l

h

Fig. 2.7

PARTICULAR POSITION OF A POINT

H(x , y, 0)

V(x, 0, z)

L (0, y, z)

K (x, 0, 0)

M(0, y, 0)

N(0, 0, z)

H [H]

V [V]L [L]

K[H] [V]M[H] [L]N[V] [L]

Gi h i A1(20 40 30) f A1 d A2


31/38

8-Jan-14 31

Given the point A1(20; -40; 30), represent epuraof A1and A2, its symmetrical to the origin. Towhat trihedral these points belong? Solution:the coordinates of the point A2are obtained by

changing the sign of the point A1 all coordinates A2(-20; 40; -30). A1T2,and A2T8 (Fig.2.8)

ya1

za1

xa1y1a1

a1a1

a1

xa2

za2

ya2

y1a2

a2

a2a2

z

x 0

y1

y

Fig. 2.8


32/38

8-Jan-14

3 STRAIGHT LINE IN DESCRIPTIVE GEOMETRY

y

x

z

[V]

[H]

[L]

0

H=h h

h v

d

D

d

V=v

L=l

v

l

d

l

Fig. 3.1

);;;0(;][

);;0;(;][

)0;;(;][

zyLLLD

zxVVVD

yxHHHD

32


33/38

8-Jan-14

3.1 LINE TRACES.POINT LOCATED ON A STRAIGHT LINE.

;"d"m;'d'm

;dm

DM

y

x

z

[V]

[H]

[L]

0

m

xm

zm

m

m

ym1

ym

y1

L=l

V=v

l

v

l

vh

h

H=h

dd

d

y=0

x=0

x=0

z=0

y=0

z=0

Fig. 3.2

);;;0(;][

);;0;(;][

)0;;(;][

zyLLLD

zxVVVD

yxHHHD

33


34/38

348-Jan-14

3.2 PARTICULAR POSITIONS OF A STRAIGHT LINE

They are two types of particular positions for a line:

Straight line parallel to a plane of projections;

Straight line parallel to two planes of projections,

that means perpendicular to the third.


35/38

358-Jan-14

STRAIGHT LINE PARALLEL TO THE HORIZONTAL PLANE [H],

is named horizontal lineor level line and

it has all its points to the same distance from the plane [H]:

;y0||"n

;x0||'n

1

]H[||)"n;'n;n(N z = const.

Fig. 3.3

z

n v a bv la bl n

x v 0 y1

a

bl

n

y

sizetrue

sizetrue

yn

xn

ABab

;0||"

;0||'

1


36/38

8-Jan-14 36

1. Given the point A(40; 30; 50),change the abscissa, depth

and quota of A, to make it belong to every eight trihedrals.

Represent these B, C, D, E, F, G, andI points in epura.

2. Given the point A(50; 20; -30)represent it in epura

together with the pointsBsymmetrical of Ato [H];C- symmetrical of Ato [V];

D- symmetrical of Ato [L];

E-symmetrical of Ato 0x;

F- symmetrical of Ato 0y;

G- symmetrical of Ato 0z.

HOME WORK HW- 01: POINTS PROJECTIONS

1 2


37/38

378-Jan-14

LAB L- 01: POINTS AND STRAIGHT LINES

1. Represent in epura the points: H(40; 30; 0), V(20; 0; 40), L(0; 40;

25), K(30; 0; 0), M(0; 45; 0), N(0; 0; 50), T(0; 0; 0). Where belongs

every point ?2. They are given the points: A(70; 50; 35)and B(45; 15; 20).Obtain the

traces H and Vof the line define by the points Aand B.

3. They are given the points: A(10; 25; 40), B(35; 5; 10)and M(70; 50;

40).Construct the rhombus [ABCD],if one of its diagonals is located

on the line defined by the points Aand M.

1 3

2

POINTS S G S


38/38

8-Jan-14 38

LAB L- 01: POINTS AND STRAIGHT LINESOnly for mechanics.

4. Construct the level line of z = 30, which intersects the straight lines defined

by the pair of points A(125; -45; 45),B(25; 50; 10), and K(65; 55; 15), L(10; -30; 55).

5. Given the points: A(25; 10; 25), B(45; 55; 60) and C(75; 15; 55), construct

the parallelogram [ABCD]. Find the intersection of this parallelogram with the

[V]plane. Draw with dashed line the hidden part of the parallelogram.

4 5

Documents

C 1 2013 engineering graphics