sheet metal forming

Question 1

What is sheet metal forming?

Answer 1

sheet metal forming describes the cutting and forming operations on thin “sheets” of metal

Question 2

What is the typical size of sheets?

Answer 2

0.5-6mm thickness, above 6m is referred to as plate

Question 3

What are the two typical materials used in sheet forming

Answer 3

1:low-carbon steel 2:aluminium

Question 4

What type of forming is carried out for sheet metal?

Answer 4

cold forming

Question 5

Production and formability of a sheet is determined by what?

Answer 5

it’s mechanical properties

Question 6

What are four possible states of stress?

Answer 6

1:uniaxial 2:Biaxial 3:triaxial 4:hydrostatic

Question 7

what type of stress provides a driving force for plastic deformation?

Answer 7

shear stress

Question 8

what is the result of tensile stresses on a sheet?

Answer 8

crack growth or void formation

Question 9

what type of stress hinders cracks and closes voids?

Answer 9

compressive

Question 10

what type of stress state is the workpiece subjected to during sheet deformation processes?

Answer 10

two dimensional biaxial stresses

Question 11

Sheet metal formability is defined as what?

Answer 11

the abillity of the metal to undergo the desired shape change without failures such as necking and tearing

Question 12

what is part drawability and whate are four things that it depends on?

Answer 12

limit of deformation, depends on 1:properties of the sheet metal 2:lubrication and surface conditions at various interfaces between the sheet and tooling 3: part geometry 4:tooling and equipment

Question 13

What is the difference in conditions between a standard tensile test and a Fheet metal formabillity test?

Answer 13

tesnile test only provides ductility work hardening etc, but doesn’t truly replicate conditionsof biaxial stretching that occurs in sheet metal forming

sheet metal formability test are designed to measure the properties under condition similar to that of sheet metal forming

Question 14

Name some common sheet formability tests (10)

Answer 14

uniaxial tensile

plane strain

biaxial stretch

bending

olsen cup

limiting dome

hydraulic bulge

fukui conical cup

conical cup wrinkling

yoshida buckling

Question 16

Describe the erichsen cupping test, what is the erichsen number?

Answer 16

a sheet formabillity test that allows effects of tool-workpiece interaction and lubrication on formability to be studied

A sheet metal specimen is hydraulically punched at 1000kg with a 20 mm steel ball

the distance between the top flat surface and the surface that has been pushed down by the ball is the erichsen number