manufacturing engineering - metal forming, bending, sheering

8/17/2019 Manufacturing Engineering - Metal Forming, Bending, Sheering

1/14

Metal Forming


2/14

Basic types of deformation process

1. Bulk deformation – Rolling

– Forging

– Extrusion – Wire and bar drawing

2. Sheet metal stamping

– Shearing (blanking – Bending

– !eep drawing

– "ther processes


3/14

Sheet Metalworking

• Forming and cutting operations on sheets# strips# and coins$

• Work parts with high surface area%to%&olume ratio$

• 'old working process using tools like punch or die$

Bending Deep drawing

Shearing


4/14

Shearing

• sheet%metal cutting operation alonga straight line between two cutting edges


5/14

Shearing

• Shearing# Blanking and )unching – Shearing % 'utting on sheet%metal with straig

ht edges$

– Blanking % 'utting sheet%metal with a closed contour$

– )unching % Making holes on sheet%metal$


6/14

Shearing

• Sheet%metal 'utting

Fine blanking-

closetolerancesand smoothedges in one

step.

Trimming - Cutting operation to remove excess metal

Shaving - Shearing with very small clearance to obtain accurate

dimensions. secondary or !inishing operation.


7/14

Shearing

• Sheet%metal 'utting c=at c = clearance

a = allowance

t = thickness

Blanking:

Blanking punch dia. =

Db- 2c

Blanking die dia. = Db

PunchHole unch dia. = D

".#$° to %.$°


8/14

Shearing

• llowance a for three sheet metal groups

&etal group a

%%""S and $"$#S aluminum alloys alltempers

"."'$

#"#'ST and ("(%ST aluminum alloys) brassso!t cold rolled steel so!t stainless steel

"."("

Cold rolled steel hal! hard) stainless steel hal!hard and !ull hard

"."*$


9/14

Sh ring

Punch Force

• Maximum punch force F

can be estimated !rom

• +riction between the punc

h and the wor,piece can i

ncrease punch !orce

Copyright #"%" earson /ducation South 0sia te 1td

T 2 sheet thic,ness

L 2 total length sheared

3TS 2 ultimate tensile strength o! the

material

( )UTS TL F 7.0=


10/14

Sh ring

EXAMPLE 16.1

Calculation of Punch Force

/stimate the !orce re4uired !or punching a #$-mm diamete

r hole through a 5.#-mm thic, annealed titanium- alloy Ti-( 0l-'6 sheet at room temperature.

Solution

7e!erring to Tab. (.%" 3TS !or this alloy is %""" &a thus

Copyright #"%" earson /ducation South 0sia te 1td

( ) ( ) ( ) ( ) ( ) MN18.010100025327.0 7 == −π F


11/14

• Straining sheetmetal around a straight axis to take a permanent bend

• Metal on inside of neutral plane is compr

essed# while metal on outside of neutral plane is stretched

Bending


12/14

• *+bending % performed with a *+shaped die

• Edge bending % performed with a wiping die

Bending


13/14


14/14

Edge Bending

• For high production

• )ressure pad re,uired

• !ies are more complicated and costly

manufacturing engineering - metal forming, bending, sheering

Documents