Bulk Deformation Processes Review Questions Flashcards Preview

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Flashcards in Bulk Deformation Processes Review Questions Deck (22)
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1

What are reasons why bulk deformation processes are important commercially and technologically?

  • Capable of significant shape change when hot working is used
  • Positive effect on part shape
  • Produce little material waste
  • Some are net shape processes

2

Name all basic bulk deformation processes

  • rolling
  • forging
  • extrusion
  • wire and bar drawing

3

What is rolling basic bulk deformation processes

Deformation process in which the thickness of the workpiece is reduced by compressive forces exerted by two opposing rolls

 

Rolls rotate, thus pulling and simultaneously squeezing the workpiece between them

4

What is a two-high rolling mill

COnsists of 2 opposing rolls between which the work is compressed

5

What is a reversing mill in rolling

Two high rolling mill in which the direction of rotating rolls can be reversed to allow the work to pass through either side

6

what is forging

deformation process in which work is compressed between two dies using either impact or gradual pressure to form part

7

One way to classify forging ops is the degree to which the work is constrained in a die; by this classification, name three basic types

 

open die forging

 

closed die forging

 

flashless forging

8

Why is flash desirable in impression die forging

As flash begins to from, friction resists continued flow of metal into gap, constraining bulk of the work material to remain in the die cavity

9

fwhat are two basic types of forging equipment

forging hammers

 

forging presses

10

what is isothermal forging

hot forging operation in which the workpart is maintained at or near its starting elevated temperature during deformation, usually by heating the forging dies to same elevated temperature

 

metal flows more readily and the force required to perform process is reduced

11

what is extrusion

compression process in which work material is forced to flow through a die opening to produce desired cross sectional shape

12

distinguish between direct and indirect extrusion

Direct extrusion / forward extrusion

metal billet loaded onto a container and a ram compresses the material, forcing it to flow through one or more openings in a die at the opposing end of the container

 

Indirect Extrusion

Die is located on the ram

13

List some products produced on a rolling mill

  • flat sheet and plate stock
  • round bar and rod stock
  • railroad track rails
  • I Beams
  • Channels
    • C-Channel
    • L-Channel

14

what is draft in a rolling op

Difference between the starting thickness and the final thickness as the workpiece passes between the 2 rolls

15

what is sticking in a hot rolling operation

COndition in hot rolling in which the surface of the workpiece adheres to the rolls as the piece passes between them, causing severe deformation of the metal below the surface in order to allow passage through roll gap

16

Identify some of the ways in which force in flat rolling can be reduced

  • Use hot rolling
  • reduce draft in each pass
  • use smaller diameter rolls

17

Name some products made by extrusion

tubes

 

bars

18

why is friction a factor in determining ram force in direct extrusion but not a factor in indirect extrusion

Problem with direct extrusion is the friction that exists between the work surface and the walls of the container as the billet is forced to slide towards the die opening on the other side of the container

 

Not present in indirect where die is on the ram

19

what are wire and bar drawing

drawing

operation where cross section of a bar, rod, wire achieved by pulling it through a die opening

 

bar drawing

large diamater bar and rod stock

 

Wire drawing

Small diamatere stock

20

although workpiece in a wire drawing is obviously subjected to tensile strength, how do compressive stresse also play a role in the process

Compressive stresses are present in wire drawing because the starting metal is compressed as it is forced through the approach of the die opening

21

In a wire drawing drawing operation, why must the drawing stress never exceed yield strength of the work

Because if the drawing stress exceeded the yield strength, the metal on the exit side of the draw die would stretch rather than force metal to be pulled through the die opening.

22