Advanced

Indication of cracking during pressing of advanced thin plates using an AE-based monitoring system

Gabrielson, Per LU ; Skåre, Thomas LU and Ståhl, Jan-Eric LU (2010) Tools and Technologies for the processing of ultra high strength steels: IDDRG 2010 International Conference In Tools and Technologies for the Processing of Ultra High Strength Steels: IDDRG Conference Proceedings ; 50th Anniversary Conference, 2010 May 31 - Juni 02, Graz, Austria p.925-934
Abstract
The acoustic emission that is detectable in the forming of complex thin part

plates contains information about the quality of the pressed plates. The information can

be used as process control and to filter out advanced thin plates with defects such as

cracks.

The article describes the results obtained in a try-out pressing process in special

developed punch-die pairs with different pressing depths in a press at Alfa Laval in

Lund. At the trials two module testing tools called SE30 and SE25 were used to create a

different degree of formability by different surface enlargement in the same complex

original design. Used sheet materials were stainless steel and two... (More)
The acoustic emission that is detectable in the forming of complex thin part

plates contains information about the quality of the pressed plates. The information can

be used as process control and to filter out advanced thin plates with defects such as

cracks.

The article describes the results obtained in a try-out pressing process in special

developed punch-die pairs with different pressing depths in a press at Alfa Laval in

Lund. At the trials two module testing tools called SE30 and SE25 were used to create a

different degree of formability by different surface enlargement in the same complex

original design. Used sheet materials were stainless steel and two qualities of titanium.

The used measuring system was based on a PC with AE-sensor of model 8152 from

Kistler.

The results of experiments show that it is possible to detect and distinguish the

plates that fracture during the forming operation. For a large number of plates detectable

signals from areas close to cracks with only local necking were also obtained. This local

necking cannot or can hardly be detected by light-test or light detecting equipment.

The left figure shows a metal sheet

with fractures and the right figure

describes measured acoustic

emission as a function of time and

the number of the details. In this

example the first four plates are

fractured and the last five plates are

without any fractures. There are several differences between the two types of signals of

acoustic emission. The signal that indicates cracking of the plate differs by a sudden

high acoustic emission and also a slightly lower level before the crack formation is

started. Before the fracture occurs the sheet metal is stretched out and the lower level of

acoustic emission also indicates less movement of the sheet metal just before the time of

fracture. The purpose of the conducted experiment was to find out whether the selected approach

was appropriate. The obtained result shows unambiguously that the chosen approach is

pertinent and that an AE-based monitoring system can be used as a process control

system to ensure the quality of production of advanced thin plates in stainless steel and

titanium. Information can be saved from the main forming operation and can be used to

see trends both long and short term. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
keywords
complex, process control, acoustic emission, stainless steel, forming, titanium
in
Tools and Technologies for the Processing of Ultra High Strength Steels: IDDRG Conference Proceedings ; 50th Anniversary Conference, 2010 May 31 - Juni 02, Graz, Austria
editor
Kolleck, Rolf
pages
925 - 934
publisher
Verlag der Technischen Univiversität Graz
conference name
Tools and Technologies for the processing of ultra high strength steels: IDDRG 2010 International Conference
ISBN
9783851251081
language
English
LU publication?
yes
id
e46e2f41-a794-4326-be2a-4cab48f71388 (old id 4378551)
date added to LUP
2014-03-31 11:22:06
date last changed
2016-07-05 14:53:00
@misc{e46e2f41-a794-4326-be2a-4cab48f71388,
  abstract     = {The acoustic emission that is detectable in the forming of complex thin part <br/><br>
plates contains information about the quality of the pressed plates. The information can <br/><br>
be used as process control and to filter out advanced thin plates with defects such as <br/><br>
cracks. <br/><br>
The article describes the results obtained in a try-out pressing process in special <br/><br>
developed punch-die pairs with different pressing depths in a press at Alfa Laval in <br/><br>
Lund. At the trials two module testing tools called SE30 and SE25 were used to create a <br/><br>
different degree of formability by different surface enlargement in the same complex <br/><br>
original design. Used sheet materials were stainless steel and two qualities of titanium. <br/><br>
The used measuring system was based on a PC with AE-sensor of model 8152 from <br/><br>
Kistler. <br/><br>
The results of experiments show that it is possible to detect and distinguish the <br/><br>
plates that fracture during the forming operation. For a large number of plates detectable <br/><br>
signals from areas close to cracks with only local necking were also obtained. This local <br/><br>
necking cannot or can hardly be detected by light-test or light detecting equipment. <br/><br>
The left figure shows a metal sheet <br/><br>
with fractures and the right figure <br/><br>
describes measured acoustic <br/><br>
emission as a function of time and <br/><br>
the number of the details. In this <br/><br>
example the first four plates are <br/><br>
fractured and the last five plates are <br/><br>
without any fractures. There are several differences between the two types of signals of <br/><br>
acoustic emission. The signal that indicates cracking of the plate differs by a sudden <br/><br>
high acoustic emission and also a slightly lower level before the crack formation is <br/><br>
started. Before the fracture occurs the sheet metal is stretched out and the lower level of <br/><br>
acoustic emission also indicates less movement of the sheet metal just before the time of <br/><br>
fracture. The purpose of the conducted experiment was to find out whether the selected approach <br/><br>
was appropriate. The obtained result shows unambiguously that the chosen approach is <br/><br>
pertinent and that an AE-based monitoring system can be used as a process control <br/><br>
system to ensure the quality of production of advanced thin plates in stainless steel and <br/><br>
titanium. Information can be saved from the main forming operation and can be used to <br/><br>
see trends both long and short term.},
  author       = {Gabrielson, Per and Skåre, Thomas and Ståhl, Jan-Eric},
  editor       = {Kolleck, Rolf},
  isbn         = {9783851251081},
  keyword      = {complex,process control,acoustic emission,stainless steel,forming,titanium},
  language     = {eng},
  pages        = {925--934},
  publisher    = {ARRAY(0x93c4668)},
  series       = {Tools and Technologies for the Processing of Ultra High Strength Steels: IDDRG Conference Proceedings ; 50th Anniversary Conference, 2010 May 31 - Juni 02, Graz, Austria},
  title        = {Indication of cracking during pressing of advanced thin plates using an AE-based monitoring system},
  year         = {2010},
}