Sheet Metalworking Review Questions

Question 1

Identify three basic types of sheetmetalworking operations

Answer 1

• cutting
• bending
• shearing

Question 2

In conventional sheet metalworking operation, (a)what is the name of the tooling and (b) what is the name of the machine tool used in the oepration

Answer 2

(a) punch and die
(b) stamping press

Question 3

In blanking of a circular sheet-metal part, is the clearance applied to the punch diameter or the die diameter

Answer 3

blank diameter = die diameter

punch diameter smaller by twice the clearance

Question 4

What is the difference between a cutoff operation and a parting operation

Answer 4

cutoff

shearing operation in which blanks are separated from a sheet metal strip by cutting two opposite sides of the part in sequence from a sheet metal strip

parting

cutting a sheet metal strip by a punch with two cutting edges that match the opposite sides of the blank

Question 5

what is the difference between a notching and seminothcing operation

Answer 5

NOTCHING

cutting out a portion of metal from the side of the sheet/strip

SEMINOTCHING

removing a potion of metal from the interior of the sheet

Question 6

Describe each of the two types of sheet metal-bending operations: V-bending and edge bending

Answer 6

V-Bending

sheet metal is bent between a V-shaped punch and die

Edge Bending

involves cantilever loading of the sheet metal

Question 7

For what is the bend alloawnce intended to compnesate

Answer 7

stretching of the metal that occurs in a bending operation when the bend radius is small relative to stock thickness

Question 8

WHat is spring back in sheet metal bending

Answer 8

increase in included angle of the bent part relative to the included angle of the forming tool after the tool is removed

tendency of metal to partially return to its original state after a bend.

Question 9

Define drawing in the context of sheet metal working

Answer 9

sheet metalworking operation used to make cup-shaped, box-shaped, complex-curved, and concave parts

Question 10

what are some of the simple measures used to assess the feasibility of a proposed cup-drawing operation

Answer 10

• drawing ratio
  Dr = D/Dp
• reduction
• thickness to diameter ratio

Question 11

Distinguish between redrawing and reverse drawing

Answer 11

Redrawing

If shape requiring drawing is too severe, complete forming of the part may require multiple drawing steps, redrwing is that second step

Reverse drawing

drawn part is positioned face down on the die so that the second drawing operation produces a new configuration.

Question 12

What are some possible defects in drawn sheet-metal parts

Answer 12

• wrinkling in flanges
• wrinkling in walls
• tearing
• earing
• surface scratches

Question 13

What is embossing

Answer 13

forming operation used to create indentations in the sheet, such as raised lettering or strengthening ribs

some strecthing and thinning of metal involved

Question 14

what is strecth forming

Answer 14

simultaneously strecthing and bending the sheet-metal work part to achieve shape change

Question 15

what are two basic catagories of structural frames used in stamping presses

Answer 15

straight sided frame presses

gap frame presses

Question 16

What is the Guerin process

Answer 16

uses a thick rubber pad to form sheet metal over a positive form block

Question 17

what are the relative advantages and disadvantages of mechanical presses versus hydraulic presses in sheet metal working

Answer 17

Faster

Not limited to deep drawing and other operations involving load-stroke characteristics

Question 18

difference between roll bending and roll forming

Answer 18

roll bending

operation in which usually large sheet-metal or plate-metal parts are formed into curved sections by means of rolls

roll forming

continous bending process in which opposing rolls are used to produce long sections of formed shapes from coil or strip