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Maximization of output capacity of hot strip mills

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Commission of the European Communities
technical steel research
Mechanical working
MAXIMIZATION OF THE CAPACITY FOR WORK
OF HOT WIDE STRIP MILLS
Report
EUR 8624 EN
Blow-up from microfiche original Commission of the European Communities
technical steel research
Mechanical working
MAXIMIZATION OF THE CAPACITY FOR WORK
OF HOT WIDE STRIP MILLS
H.D. PLUM, M. TONCOURT
VEREIN DEUTSCHER EISENHÜTTENLEUTE
Postfach 8209
D-4000 DÜSSELDORF 1
Contract No 7210-EA/104
(1.8.1977 - 31.12.1981)
FINAL REPORT
Directorate-General
Science, Research and Development
1986 Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General
Telecommunications, Information Industries and Innovation
L-2920 LUXEMBOURG
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting
on behalf of then is responsible for the use which might be made of
the following information
ECSC-EEC-EAEC, Brussels · Luxembourg, 1986 VDEh BETHIEBSFOESCHUNGSINSTITUT
Summary
This report is sub-divided into two parts.
The objective of the first part was to determine
means of reducing the fault frequency in the
finishing trains of hot wide strip mills. By means
of moving and single-picture records the run-in
behaviour of the strips in the rear part of the
finishing train and the geometric shape of the
strips were investigated in three mills, and the
geometry of the roughed strip in one mill.
The evaluation revealed that neither the geometric
shape of the roughed strip, nor that of the
running-in finishing strip is appropriate as
control variable for the strip-specific
influencing of the entry behaviour.
Simulation tests with a test roll stand showed
that even a geometric modification of the guides
failed to ensure major advantages as against
known designs.
In the second part of the investigation, a
simulation system for the capacity calculation of
hot wide strip mills was developed. The system
includes the units of a hot strip mill as modules,
and thus allows a simulation of various mills. The
system was realized as computer simulation model
in the language BONANÇA (Bottle neck analysis by
determination of critical activities) and
implemented on a Siemens Computer 7.531, BONANÇA
enables the quantitative analysis of production IV-
VDEh BETRIEBSFORSCHUNGSINSTITUT
system bottle necks with the aid of production and
evaluation review technique.
The simulation system was used to simulate a 3/4
continuous-mill and to investigate the effect of
the way of operation and interruptions on the output
of the mill. -ν
VDEh BETRIEBSFORSCHUNGSINSTITUT
Contents
Page
1. Preface 1
2.Investigation into the main cause
ofinterrruption "Finishing train 6 guide"
2.1 Investigations into the running
8behaviour of the strip
2.1.1 Arrangement, executionand
evaluation of thetest8
2.1.2 Test results 15
2.1.2.1 Preface15 2 Results19
2.1.2.2.1 Relationshipbetween head shape
and running-in behaviour 21
2.1.2.2.2 Influence of the steelquality
and the casting methodonthe
head shape and the running-in
behaviour 37
2.1.2.2.3 Influenceofthe shape of the
roughedstrip43
2.1*2.2.4 Transitionprobabilities for head
shapeandrunning-in type of the
finishing strips51
2.2 Geometry of the guides 57
2.2.1Roll stand andguides57
2.2.2 Test execution andtestresults 59-VI
VDEh BETRIEBSFORSCHUNGSINSTITUT
3. Model for the capacity computation
and bottle neck analysis of
rolling mills 67
3.1 Description of the modules 6
3.1.1 Slab feed
3.1.2 Furnace9
3.1.3 Slab delivery
3.1.4 Roller table 71
3.1.5 Roll stand (roughing train) 73
3.1.6 Finishing train5
3.1.7 Coiler6
3.1.8 Slab7
3.2 Method applied 7
3.2.1 Employment of the method for the
model hot wide strip mill 80
3.2.2 Exemplary representation of how
the method works for the model
hot wide strip mill 85
3.3 Simulation of a 3/4- continuous mill 93
3.3.1 Description of the mill 93
3.3.2n results
3.3.2.1 Long thin strip 96 2 Short thick strip9
3.3.2.3 Mixed program without interruptions 101
3.3.2.4-dm withs 104
3.3.2.5 Capacity changes 105 VDEh BETRIEBSFORSCHUNGSINSTUT
1. Preface
In the European Community in 1980 about 4-5
million tons of hot strip were produced in 25
mills. To this the Federal .Republic of
1 ?
Germany ) ) contributed 15 million tons, which
were rolled in 6 mills.
The expense for the conversion of the raw
steel is in this stage essentially determined
by the costs of investments, which, dependent on
work load and mill sizes, lie between 30 % and
4-5 % of the processing cost ( figure 1 ).
Therefore, in such plants the question of the
capacity for work is at issue as much as
anything.
It is determined by the plant output in the
available work-time and the net product obtained
with this in the industrial sense of gross yield.
Whereas the latter value is an indication for
the plant economy and is affected by factors
inside and outside of the plant and branch of
industry, the productiveness as an essential
partial aspect is chiefly determined by the
framework of the technical-industrial conditions
of the very branch of industry ( figure 2) .
1 N
) Statistic Year-book of the Steel and Iron Industry
1981
2 ) Plant Data Bank, Institute for Industrial Research,
Dusseldorf VDEh BETRIEBSFCRSCHUNGSINSTITUT
The aim of the research plan was in the first place
to obtain data per time unit on the output of hot
wide strip mills, to draw inferences from same
regarding any possible weak points of a plant-
technical nature and to acquire as far as possible
indications for their elimination.
On this basis, by means of applying the data
obtained, a computation model was to be set up with
the aid of which the ton capacity of rolling mills
could be determined and also exact bottle neck
analyses could be carried out.