UDC:
621.5/.6:665.7:681.5:061.3(047)=20
COSATI: 13-07, 20-04, 14-02
Dragoljub Vujić, PhD
(Eng)[1])
|
T |
HE 28th
scientific-professional meeting with interna-tional participation-HIPNEF 2002
was held in Vrnja-čka Banja from 2nd to4th October, 2002. The meeting was
organized by the Faculty of Mechanical Engineering from Niš, with the
Association of Mechanical and Electrical Engineers and Technicians of Serbia
(SMEITS) from Bel-grade as a coorganizer.
This year's
meeting started with the following introdu-ctory lectures:
1. DEVELOPMENT OF SERBIA AS INNOVATIVE SOCIETY
Professor
Dragan Domazet, PhD, the Republic of Serbia Minister of Science, Technology and
Development
2. STUDY OF NONSTATIONARY FLOWS
Professor
Zoran Boričić, PhD, Professor Dragiša Nikodijević, PhD, Professor Dragica
Milenković, PhD
3. SLIDING REGIMES IN AUTOMATIC CONTROL SYSTEMS
Professor Čedomir Milosavljević,
PhD
The lecture
of Minister Domazet was especially intere-sting. He began by expressing his
admiration for the organizers who had been able to prepare the meeting in spite
of the difficult transitional period our economy is facing. In the continuation
of his report, he introduced the research programmes planned for the year 2002,
and highlighted the efforts undertaken by the Ministry to put cumulated knowledge
in the function of our country's development.
Over 100
registered participants attended the meeting. A number of representatives from
various universities, colleges and institutes, experts from our country and
abroad have been present. Our experts in economy have participated in the
HIPNEF meeting for the first time, introducing some interesting strategic
planning and marketing papers. Our people living and working abroad, it is
worth pointing out, are interested in intensifying the cooperation with our economy
representatives and firms.
Two independent sections worked during the meeting, with the total of
110 papers revised beforehand by the organizers and parallelly presented. The
proceedings distri-buted to the participants include papers from the following
areas:
–
HYDRAULICS (22
papers)
–
PNEUMATICS (8
papers)
– ELECTROTECHNICS AND
ELECTRONICS (10 papers)
–
FLUIDS (8 papers)
–
FLEXIBLE CONTROL
SYSTEMS (27 papers)
–
FLEXIBLE
AUTOMATION (12 papers)
–
EXPLOITATION AND
MAINTENANCE (9 papers)
Some of the papers presented at this meeting are espe-cially worth
mentioning, as they deal with new technologies and research techniques in the
domains of HIPNEF.
Tomislav
Vićovac, a representative of a Yugoslav-Svedish firm Water jet Yugoslavia, has
presented a technique of waterjet cutting. Waterjet technology is a modern,
unconventional, mathematically justified technology of cold cutting applicable
to almost all materials and any
two--dimensional contour. It can cut steel up to 100 mm and other
materials up to 150 mm of thickness. The cutting accuracy is 0,1 mm per meter,
the cut is 0,8 mm to 1,05 mm wide with treatment quality 9. A narrow cut is
suitable for the optimum efficiency of expensive materials such as titanium,
compound materials and optical glass. The working pressure ranges from 3200 bar
to 3600 bar and the velocity of water and abrasive material, added only when
solid materials are cut, is approximately 1000 m/s. This method is suitable for
compound and plastic materials sensitive to heat and mechanical damage.
Dejan
Šiljaković MSc, a Bosch Rexroth Group representative, has presented a special
procedure of ceramic protection of hydraulic cylinder piston rods in "Ceramic
Protection of Hydraulic Cylinder Piston Rods (CERA-MAX) and Integrated Systems
for Cylinder Piston Stroke (CIMS, CIAMS)". This procedure enables
a long-lasting functioning of hydraulic cylinders under difficult working conditions,
unlike the conventional protection technologies of nickel and chromium plating.
A special powder is applied to the material surface using plasma, or the
so-called HVOF (High Velocity Oxygen Fluid) procedure. The result is an ideally
smooth surface of the piston rod with excellent mechanical and chemical
properties, resistant to corrosion and harmful chemical influence. This paper
includes a chronological development of corrosion protection. Originally,
fusible metals like Zn, Al, Mo, etc. were used for coating basic materials of
piston rods. In the further development of this process, autogenous deposition
of powdery materials such as lead, stainless steel and alloys was used. In the
domain of corrosion protection the introduction of plasma i.e. ionised gas, was
a revolutionary step. Plasma technology enabled jet deposition of zinc,
chromium and aluminium oxide, (ZnO2, Cr2O3 and
Al2O3) powders used for protection of turbines in the
aircraft Industry. Modern technology of plasma enables fine deposition of
aluminium (Al2O3) and titanium (TiO2) oxides,
which is important for hydraulic cylinder piston rod protection. With this new
technology it is also possible to apply the finest material powder such as:
stainless steel, inkonel (alloy of Cr, Ni, Fe and Si), alloys of Nickel with
admixtures, etc. the HVOF technology is the latest achievement in the field of
thermal jet protection. Powder is applied on the base surface by the gas flow
of the velocity up to 2000 m/s, developing a temperature up to 2500˚C.
High thermal and kinetic energies of the jet produce a strong bond between the
protective and basic material. A new protective layer is harder and of more
homogenous structure compared to all other protection technologies.
Along with
this technology, a process of integrating special electronic systems for
measuring cylinder strokes was presented. The technologies in question are
high-technology integrated electronic measuring systems that give great
accuracy in measuring strokes, very important features for synchronisation two
or more cylinders. The development of these systems from 1990, when the CIMS
MkI system was introduced, up to the present day is given as well. In 1995 an
improved CIMS MkII appeared. After years of research and testing, at the
Hanover Fair held this year, a prototype of the most up-to-date generation of
an absolutely integrated measuring system CIAMS, considered as a vital leap
forward, was presented. After necessary testing under extreme working
conditions and fine settings have been performed, this system is going to be
available by the end of 2002.
Speaking of
new technologies, it is important to mention the application of water instead
of oil for power transmission in hydraulic systems, presented in "Main
Characteri-stics and Application Possibilities of Water Hydraulic Systems"
by Dragoljub Vujić.
After
almost a hundred years of using oil in hydraulic systems, the environmental
protection problems impose the application of water systems. The advantages of
water hydraulics and the disadvantages of mineral oils, water/oil emulsions and
bio-oils have been particularly pointed out. The solutions for hydraulic pumps
and motors have been given, along with a family of cylinders, non-re-turn
valves, proportional valves and servo-valves. The main problem of low water
viscosity and corrosion on the hydraulic components, is solved by applying
modern materials, new technological procedures of surface treatment and parts
design. Stainless steels, brass, special types of aluminium, ceramics and a
special polymer-based plastic are used.
This paper
was mentioned on various occasions during the meeting, as an example of a new
technology which had been so far, entirely unknown and almost unthinkable even
for experts in this field.
Furthermore,
there were two interesting papers resulting from a project called "Optimal
Tribocouple Cylinder Block, Switchboard of Piston Axial Pump and Hydromotor
Research" financed by the Ministry of Science, Technology and
Development of the Republic of Serbia:
–
Model
Studying the Interaction of Inner Component Structure and Working Process of
Hydraulic Systems
Petar Ivanović MSc, CTE (College of Technical
Engi-neering), Trstenik, Dragiša Nikodijević, PhD, Faculty of Mechanical
Engineering from Niš, Nenad Ivanović, MSc, Radoš Pantić, MSc "Prva
Petoletka", Trstenik.
A model for
increasing the power density by mass unit in oil-hydraulic systems and the
working efficiency has been presented. The model is based on a multidimensional
analytic-experimental method of studying the inner structure of the components
and the working process in them.
–
New
Materials and New Technologies in the Design of Hydraulic Accessories vital
Assemblies
Radoš Pantić, MSc, Nenad Ivanović, MSc,
"Prva Petoletka" Trstenik, Dragiša Nikodijević, PhD, Faculty of
Mechanical Engineering, Niš, Petar Ivanović, MSc, CTE, Trstenik.
The
application of new technologies and materials in the production of hydraulic
pumps and motors is treated, aiming at their technical and technological
performance improvement.The bottom line is registered unconventional technology
of plasma deposition procedure.
Two more
papers from the domain of hydraulics and pneumatics are important to be
mentioned:
–
The
Present State and Prospect of Industrial Development Production and Marketing
of Hydraulic Accessories and Systems
Professor Rodoljub Tomić, PhD, Radoš Pantić,
MSc, IHP "Prva Petoletka" Trstenik.
The paper
is given from the aspect of strategic development of "Prva Petoletka"
(PPT) products in the domain of oil hydraulics until 2005. This firm, being the
leading supplier in Serbia and one of the leading manufacturers in Southeast
Europe, is ready to meet the demands of the market, either directly or through
different aspects of cooperation with foreign partners stressing the growing
importance of reliable suppliers selection, both domestic and foreign. In that
sense, a document called "Bases of Development Strategy of PPT
until 2005" has been adopted. This document may play an important
role in the "Strategy of Industrial Development of the Republic of Serbia
until 2010"
–
Expert
System of Analysing Solutions from the Domain of Pneumatics
Ljubomir Miladinović, PhD, Miodrag Aleksić,
Gvozden Dželatović, Festo Ges.m.b.H, Wien, representative body, Belgrade.
An expert
system for analysing solutions from the domain of pneumatics is described.
Through this expert system Festo firm wishes to help in solving the problems
that final users and technical advisers face in their work. Collecting
pneumatic applications, as a means of successful production, could also serve
for engineering staff improvement, both in Festo and the final users of
equipment. The collected information will prove to be profitable in the
communication between the producer and the user, which is a strategic aim of
any firm.
It is
important to mention some other events accom-panying this meeting, such as the
presentation of sponsors and new books from the domains that HIPNEF deals with.
Video presentations were especially interesting. Basic segments of production
programmes, various advertising materials and catalogues promoting sponsors
have been presented on neatly arranged stands.
The panel
initiated some of the current questions concerning the future organisation of
this meeting. It has been suggested that the meeting should become annual, and
that a journal in pneumatics and hydraulics as well as a HIPNEF site should be
launched.
It can be
concluded that this traditional meeting of experts in oil hydraulics,
pneumatics, automatic control and other similar areas, financially supported by
a number of sponsors and donors, has been well prepared and organised. The
papers presented here have been meaningful and of high scientific and
specialised level. Unlike the previous meetings, out of three papers prepared
in the MTI, the only representatives on the part of the YA, only one paper has
been presented. In spite of the difficult economic situation, the meeting has
met the expectations of the organisers and has, all in all, proved to be a
complete success.
Received: 23.10.2002.