Chapter 2 - Sheet Metal Structures Flashcards Preview

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Flashcards in Chapter 2 - Sheet Metal Structures Deck (37):
1

What are the two different types of sheet metal structures?

Monocoque and Semimonocoque

2

What are the five major stresses?

  1. Tension - primary stress that tries to pull a body apart
  2. Compression - another primary stress that tries to squeeze a part together
  3. Bending - Tries to pull one side of a body apart while at the same time squeezing the other side together
  4. Torsion - a twisting force
  5. Shear - opposing forces are applied on opposite sides of a body

3

Identify the Aluminum alloy series

1xxx

2xxx

3xxx

4xxx

5xxx

6xxx

7xxx

 

1xxx Aluminum - Pure aluminum 99% or higher

2xxx Copper

3xxx - Maganese 

4xxx - Silicon

5xxx - Magnesium

6xxx - Magnesium and silicon

7xxx - zinc

 

4

Define annealing

Annealing is a process that softens a metal and decreases internal stresses  by heating the metal to the annealing point and heald there until the metal becomes heat soaked. It is then cooled to 500 degrees F of a rate of about 50 degrees F per hour

5

Name what these aluminum alloys are commonly used for:

2117

2024

5052

7075

2117 - Mostly aircraft rivets

2024 - Majority used on structures

5052 - Gas tanks and fuel lines

7075 - When high strength is needed

6

What is alclading and why is it important?

Alclad consists of a pure aluminum coating rolled onto the surface of heat-treated aluminum alloy. The thickness of this coating is approximately 5% of the alloy's thickness on each side. Alclading a surface greatly increases the corrosion resistance of an aluminum alloy.

7

Which alloys are heat treatable and non-heat treatable?

Non-heat treatable alloy

1100

3003

5052

Heat treatable alloy

2017

2117

2024

6061

7075

8

When appropriate, the metal hardness, or temper, is indicated by a letter designation seperated from the alloy designation by a dash. Name the following temper designations:

-O

-T3

-T6

 

O - Annealed

T3 - Soulution heat-treated and cold worked by the flattening or straightening operation

T6 - Solution heat-treated and artificially aged

9

Which two series of metals are heat-treatable?

7000 & 2000 series.

All others are non-heat treatable and must be hammered or cold worked to be treated.

10

Corrosion from two dissimalar metals is called what?

Glavanic corrosion

11

Artificial aging is another name  for _______heat -treatment

Artificial aging is another name  for  precipitation heat -treatment

12

Name three disadvantages for using magnesium as a structural material.

cracks, corrodes, & burns easily

13

What is this tool and what should it and should NOT be used for?

Q image thumb

Scribe

Should be used in sheet metal work only for marking the cut-off lines of a part. They should never be used for marking dimension lines for bending metal. 

14

What is the purpose of a prick punch?

Once layout marks have been made with a soft pencil, permanent marks can be made in the location for holes with a sharp prick punch and a light tap with a small hammer.

15

What is the purpose of this tool?

Q image thumb

Center punch

Enlarges a prick punch to begin for drilling

16

What is the purpose of this tool?

Q image thumb

Pin Punch

Ideal for removing rivets

17

What is th epurpose of this tool?

Q image thumb

Kett Saw

Easily removes damaged sections of sheet metal

18

What is the purpose of this tool?

Q image thumb

Pneumatic-powered Kett Saw

performs straight line cuts

19

What is the purpose of this tool?

Name the advantages and disadvantages of this tool.

Q image thumb

Nibbler

Advantage - makes detailed inside cuts

Disadvanteges - leaves rough edges after cutting

20

What are the two cuts of files and two ways to file?

Cuts

  • Single cut - one row of teeth
  • double-cut - two rows of teeth

Methods of filing

  • Cross filing - the file is moved lengthwise across the work with the hands positioned at the edges
  • Draw filing - the file is moved across the work

21

What is the purpose of this tool?

Q image thumb

A squaring shear

Used to make straight cuts across the sheet metal

22

  What are the types of machine brakes (forming tools)?

Press brakes 

Cornice brakes

Bar folding machine

Box brake

 

All of these machines are used to make sharp bends rather than gentle curves

23

What are the three types of compound curve tools?

Stretch Press - uses a male die

Drop Hammer - Matching male and female dies are used

Hydropress - uses a male die

24

What are the advantage and disadvantage of using shrinkers and stretcher?

Shrinking and stretching tools are used to form contours in parts by expanding or compressing metal to make it form a curved surface. 

25

What are cleco fasteners used for and what are it's different colors?

Cleco fasteners are used to temperarily hold sheet metal parts together until they are riveted.

3/32 inch....(-3 diameter rivet)    Silver

1/8..................(-4 diameter rivet)    Copper

5/32..............(-5 diameter rivet)    Black

3/16...............(-6 diameter rivet)    Brass

1/4...........................................................Copper

26

What is the difference between the rivet codes for AN and MS20?

Decode the following: AN470 AD 4-4

AN - Airforce/Navy

MS20 - Military Standards 20 system

AN470 - head style

AD - Material

4-4 (diameter in 1/32 increments) (lenth in 1/16 increments)

27

Name the rivet head designs

Q image thumb

AN426/MS20426 (standard flush rivet)                     AN470/MS20470

AN442                                                                     AN430

28

Name the rivets

Q image thumb

Plain 1100 Aluminum (A)

Dimple 2117 Aluminum Alloy (AD)

Raised Cross 5056 (B) "ice box rivets"

Raised Dot 2017 (D) "ice box rivets"

Two raised dashes 2024 (DD) Raised ring 7050 (E)

 

29

How do you define strain?

The deformation of an object caused by stress

30

What is a stress-skin structure?

An aircraft without a truss frame providing a more streamline shape and reduced the weight. It is referred to having a monococoque design

31

What are the different types of fuselage designs?

Truss-type fuselage 

Stressed-skin fuselage

  • monocoque
  • semi-monoque

32

The acculuted angle for cutting is at what degree?

118 degrees

33

What are two types of drill?

 

Pneumatic

variable speed

34

What is the rule of thumb when drilling into metals?

Soft metals - Higher speed, less pressure

Hard metals - Slower speed, harader pressure

35

What is dimpling and it's two types?

When the top sheet of metal is too thin to counter-sink, the edges of the hole may be formed to accomodate the head of the rivet by using a set of dimple dies. The two types are:

Coin dimpling and Radius dimpling

36

Name the three parts of a drill

Tip - 59 degrees from the center line producing 118 degrees total

Shank - chucked into the drill motor

Body -

  • flute - aids in carrying material out of the hole
  • Land - provides a finishing dimention of the hole

37

What are the three main parts of a semmi-monocoque design?

stringer - horizontal lines

Former - vertical lines

Bilkhead - strongest part