E-mail: hriesik a rijeka.riteh.hr.
Summary: In the subject work, which represents the first part of a
pluriennal research, the actual piping manufacturing state on ships is
analyzed. The pipes quantity in size and mass in a 112000 DWT chemical
tanker building is throughly shown. The dynamics of purchasing the rough
pipes related to dynamics of piping manufacturing and fitting on board the
ship, has been analyzed. In that, the differences in the quantities
estimated by the design office related to those really mounted on board,
come out. The data gathering and their corresponding analysis, relate
to the quinguennal and decimal period between years 1981 and 1990. The
results have been analyzed, graphically processed and collected in more
diagrams and tables. The amount of scrap the necessary alterations, the
repairs and other defects in piping manufacturing have been determined.
The distribution and the dynamics of the pipes consumption from the
Contrat signing to the vessel commissioning, have been graphically shown
in particular. The collected data are indispensable as input functions
for mathematics modeling the manufacturing process and the manufacturing
system. Mathematical model for optimizing the manufacturing process has
been settled, containing the following processes: process state functions,
process limiting functions, optimizing chriteria and objective functions.
The model will lead to the manufacturing process control optimization.
Perfoming the model solution will be the subject of the second and third
part of this work.
Hereby, a presentation of the subsequent part of work on a project has
been given. Optimal plate edges heat treatment procedures and machining of
the same by use og special milling machines has been investigated. Actual
situation in shipbuilding industry has been analysed, with an emphasis on
indispensability of introduction of CAD/CAM technology, with a view to
rounding up the pipes treatment automatic systems. Worked out has been a
mathematical model of multifactor experiment for particles separation.
Also investigated has been the systems employing pneumatically driven hand
grinding machines, and electrically driven hand grinding machines fed by
increase frequency alternativecurrent. Optimum solutions have been
searched in respect of 16 objectives. Modified Zangenmeister's method
showed to be most appropriate, yielding in a noteworthy contribution to
scientific approach in researching of this technology. The results have
been presented numerically as well as in graphs through a computer aided
elaboration. Results of a tests application of a new grinding trechnology
using increased frequency el. current have also been elaborated.
Obligatory introduction of a flexible system has been argumented.
Keywords: Automatization, Machining System, Optimization, Pipe, Shipbuilding, Compressed Air, Hand Grinder, High Frequency Current, Profiling of Plate Edges, Steel Plate
Research goals: The main scope of the research is to create a
scientific basis for making decisions on investment cycle, with the aim of
increasing the degree of automation in the piping manufacturing process.
In that it is important to search after an optimum in each manufacturing
sequence. In respect that reference is made to cut down the cost of the
preparation cycle and of the manufacturing itself, as well as to lower the
scrap, to increase the cash flow by minimising the stocks, to improve the
storage organzation from a manual to a computerised level, to introduce
CNC tehnology of machining and quality control, etc.. On a considerable
number of graphs diagrams and tables one can see the totality of problems
as well as the schedule of the actual manufacturing process condition. On
a particular diagram the schedule of design work, of machining and
installation of pipings board the ship is presented. Also a special
schedule appeiend to a chemical tanker of 112000 DWT from the signing of
the Contract to the commissioning of the vessel to the Owner has been
elaborated. Particularity a quinquennial and a decennial period of
machining and installation of piping different sizeshave been analysed.
This will represent an important input function for modelling the
production capacity. Distribution of pipes according to dimensions and
mass for different vessel types(bulkcarrier, tanker and chemical tanker),
has been elaborated. The following results are expected from the
research:relatively large discontinuity in loading the production
complexand the labour; the purchasing of pipes and equipment
throughwholesale trades is unsafe, and it is also not organised
on-linewith the productions facilities; low capital flow because of
nonconformity of the pipes purchasing terms with those of theirinstalling;
the introduction of CNC technology in the workingprocess is at an initial
stage; the percentage of scrap of thenecessary repairs, of alterations,
etc., is rather high, so it isnecessary to introduce new quality control
organisation for thepiping; there are still reserves to take a profit of
increasingthe fitting of the piping in the ship blocks (modules),
insteadof doing that after the launching of the ship.
Objectives ensuing from preliminary communication call for
optimum production in actual conditions through application of particular
systems and subsystems. It was thus necessary to investigate optimality of
plate cutting and pipe machining systems employing plasma and oxyacetilene
devices, as well as those involving special milling machines. Modern
machines, along with the CNC machines, are quite preferably to be given
absolute priority. Pneumatically driven hand grinding machines, today more
or less prevailingly in use for certain number of operations, represent
technological subsystem in this field. Introducting of electrically driven
hand grinding machines that employ el. current of increased frequency is
rather not recommendable without a prior comprehebsive and thorough
analysis of all relevant parameters, inasmuch as adaption of those
machines calls for substantially high investments. Investigative research
of the mentioned two systems (pneumatically and increased frequency el.
current) should supply results of particular significance for
technological improvements, improved ergonomically aspects, production
economy, costs savings, and consequently, a reduction in products prices.
It is due to the variety of ship designs, meaning various purposes built
ships that inexorably is to require for the flexible, automated lines for
machining of plates, profiles, pipes and eventually other elements, to be
COOPERATION - INSTITUTIONS
Name of institution
: Brodograđevna industrija "3. maj" Rijeka Type of institution: Economical/Production Type of cooperation: Joint publishing of scientific papers City: 51000 - Rijeka, Croatia
Name of institution
: Brodogradilište "Uljanik" Pula Type of institution: Economical/Production Type of cooperation: Occasional exchange of information City: 52000 - Pula, Croatia