Indication of cracking during pressing of advanced thin plates using an AE-based monitoring system
Författare
Redaktör
- Rolf Kolleck
Summary, in English
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.
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.
Avdelning/ar
Publiceringsår
2010
Språk
Engelska
Sidor
925-934
Publikation/Tidskrift/Serie
Tools and Technologies for the Processing of Ultra High Strength Steels: IDDRG Conference Proceedings ; 50th Anniversary Conference, 2010 May 31 - Juni 02, Graz, Austria
Dokumenttyp
Konferensbidrag
Förlag
Verlag der Technischen Univiversität Graz
Ämne
- Materials Engineering
Nyckelord
- complex
- process control
- acoustic emission
- stainless steel
- forming
- titanium
Conference name
Tools and Technologies for the processing of ultra high strength steels: IDDRG 2010 International Conference
Conference date
2010-05-31 - 2010-06-02
Conference place
Graz, Austria
Status
Published
ISBN/ISSN/Övrigt
- ISBN: 9783851251081