[0001] The present invention relates to a method for supervising rolling mills, particularly
for the on-line control of the rolling process in Sendzimir-type mills. More particularly,
the invention relates to a rolling supervision method which is suitable for mills
of the reversible type with a single housing.
[0002] It is known that single-housing mills are used to roll steel coils which are unwound
from a feeder reel ahead of the housing and are wound on a takeup reel after the housing.
[0003] In order to perform rolling, it is necessary to perform multiple passes through the
housing and therefore the takeup and feeder reels reverse their direction of rotation
each time so as to switch from feeding to takeup and vice versa.
[0004] Rolling schedules, that is to say, schedules which take into account the rolling
parameters for the type of material, the final intended gauge, the type of mill used,
any process tolerances et cetera, are currently prepared by manual input of these
parameters by operators; the drawback of this method is that it requires the presence
of specialized operators in addition to considerable time to prepare said schedules.
[0005] Furthermore, coils of material of the same type can be rolled differently by different
operators, consequently not ensuring uniform production.
[0006] Manual input of the parameters by the operator requires considerable experience together
with in-depth knowledge of the mill on which the operator intends to work.
[0007] This leads to drawbacks from the point of view of production times and from the point
of view of costs.
[0008] Furthermore, the mill is never utilized to full capacity as regards its operating
speeds and the type of rolling that can be performed on the steel strips to be rolled.
[0009] The aim of the present invention is therefore to provide a method for supervising
mills, particularly for Sendzimir-type mills, in which schedule preparation is performed
in an automated manner.
[0010] Within the scope of this aim, an object of the present invention is to provide a
method for supervising mills, particularly for Sendzimir-type mills, in which there
is a program providing an interface between a high-level mill supervisor program and
a mathematical model meant to prepare the rolling schedules.
[0011] Another object of the present invention is to provide a method for supervising mills,
particularly for Sendzimir-type mills, in which it is possible to monitor the rolling
process on-line.
[0012] Another object of the present invention is to provide a method for supervising mills,
particularly for Sendzimir-type mills, which is highly reliable, relatively easy to
provide and at competitive costs.
[0013] This aim, these objects and others which will become apparent hereinafter are achieved
by a method for supervising a rolling mill, particularly for the on-line control of
the rolling process in Sendzimir-type mills, characterized in that it comprises the
steps that consist in:
- interfacing the user with a mathematical model which is suitable to generate rolling
schedules on the basis of parameters related to the type of material to be rolled
and to the type of mill used, and periodically activating said mathematical model;
- supplying the mathematical model with the parameters required to determine a rolling
schedule which is suitable for the material to be rolled;
- activating the various functions of the mathematical model according to the current
rolling events; and
managing the output information of the model in order to feed it back to a higher-level
supervisor system which is suitable to control the rolling process.
[0014] Further characteristics and advantages of the invention will become apparent from
the description of a preferred embodiment thereof, illustrated only by way of non-limitative
example in the accompanying drawings, wherein:
- figures 1a-1b are flowcharts of a first routine of the method according to the present
invention;
- figures 2a-2c are flowcharts of a second routine of the method according to the present
invention;
- figures 3a-3e are flowcharts of a third routine of the method according to the present
invention;
- figures 4a-4c are flowcharts of a fourth routine of the method according to the present
invention; and
- figures 5a-5b are flowcharts of a fifth routine of the method according to the present
invention.
[0015] With reference to the above figures, the method according to the present invention
is configured as follows.
[0016] The system for supervising mills of the flat-bed reversible type, to which the present
invention relates, includes among its functions a mathematical model for generating
rolling schedules. Rolling schedules contain the preset parameters of the mill, such
as rolling speed, rolling force, reel pulling force, gauge reduction for each rolling
pass, et cetera.
[0017] First of all, the functions of a mathematical model provided for creating rolling
schedules in an automated manner are described; this is followed by a description
of the routines, shown in the various figures, which link the master mill supervision
method to the mathematical model and allow on-line control of the rolling schedule
during rolling so as to be able to optionally modify its parameters.
[0018] In particular, the above cited routines must allow users to request services to the
mathematical model and in particular a rolling card and to configure and monitor the
activity of the mathematical level.
[0019] Furthermore, the routines must allow to collect and supply to the mathematical model
all the parameters required for its operation and in particular:
characteristics of the coil being rolled;
characteristics of the material being rolled;
process variables;
physical characteristics of the mill;
configuration parameters of the mathematical model itself.
[0020] The routines must furthermore activate the functions of the mathematical model at
the appropriate time, according to the events that occur during the rolling process.
[0021] Finally, the routines must manage the output information of the mathematical model
and in particular:
the mill preset rolling schedule;
updating of the schedule for the coil being rolled;
parameters that are automatically adapted by the mathematical model to be saved in
a permanent database;
a graphic output related to the thermal condition and wear of the rollers.
[0022] Two databases are described herein: one is a so-called real-time database, which
consists of a memory area for the rapid exchange of information among the various
processes. The second database is a conventional database in which the data to be
saved are stored.
[0023] The interaction between the above routines and the users occurs by means of man-machine
interface means, advantageously constituted for example by on-screen pages by means
of which the operators can interact with the mathematical model.
[0024] The characteristic functions of the mathematical model are now described schematically
in order to better comprehend the routines that follow, which constitute the method
according to the present invention, for the management of said mathematical model
with interaction on the part of the user.
[0025] The above mathematical model comprises four main functions: a function designated
hereinafter as SETPRE hereinafter; a function designated as SETUP; a function designated
as CYCLIC and a function designated as ADAPT.
[0026] The SETPRE function is meant to determine a preliminary rolling schedule which contains
the preset information for the mill for all the passes required to reduce the gauge
of the material being rolled until it reaches an intended final value.
[0027] This function therefore calculates the optimum number of rolling passes required,
accordingly determining, for each pass, the gauge of the strip being rolled that must
be reached and all the rolling parameters as preliminary values.
[0028] The second function of the mathematical model, designated as SETUP, is meant to update,
at the beginning of each rolling pass, the rolling schedule calculated earlier by
the SETPRE function for the coil currently being processed. This function updates
the preset information for one pass only, taking into account the current situation
of the rolling mill.
[0029] The CYCLIC function is instead meant to acquire, analyze and calculate the actual
rolling conditions and the parameters in order to continuously monitor the status
of the mill, provide short-term adaptation of the parameters related to the rollers
of the mill (wear, roughness and temperature) and preprocess the information that
will be used at the end of the rolling pass by the ADAPT function.
[0030] The ADAPT function is meant to adapt the parameters related to the materials, to
the mill, to operating practice tables et cetera.
[0031] Activation is automatic at the end of each rolling pass.
[0032] The routines shown in the figures then allow to retrieve the above cited functions
of the mathematical model and to interface these functions with a higher-level mill
supervision method in which the operator also intervenes.
[0033] The exchange of information between the mathematical model and the higher-level processes
occurs by means of the following data structures:
mill data: this structure contains information related to the configuration of the
mill;
material data: this structure contains all the information related to the characteristics
of the steels rolled in the mill.
[0034] The information related to the materials is of the static type (physical characteristics,
for example) or of the dynamic type (deformation strain strength curves which are
adapted by the mathematical model according to the information acquired during rolling);
operating data, which supply the mathematical model with information according to
the characteristics of the rolled strip;
result data generated by the CYCLIC function, which contain information on the current
status of the mill;
data for transfer between the CYCLIC and ADAPT functions: the first function, that
is to say CYCLIC, activated every 10 seconds, processes during rolling information
related to the current status of the mill and makes it available by means of the transfer
data to the ADAPT function, which is activated at the end of the rolling pass;
data related to the characteristics of the coil to be rolled or currently being rolled;
data related to the information generated by the SETPRE and SETUP functions, essentially
data for the rolling schedule to be sent to the lowest mill automation level;
process data: these data contain information related to the current status of the
rolling process. The information is received periodically by the lower automation
level and supplied by a mathematical model by means of the interface program according
to the present invention;
model parameters: these data contain the configuration parameters for the mathematical
model;
reliability data: these data contain all the information generated by a mathematical
model during the execution of the various routines that compose the various functions.
[0035] Each routine generates messages of various kinds which allow to monitor the activity
of the mathematical model;
data containing the modifications made by the operator to the rolling schedule generated
by the mathematical model: the mathematical model receives this information as input
and calculates a new schedule, taking into account the changes introduced by the operator.
[0036] The routines of figures 1 to 5 are now described in detail; said routines are executed
as interface between the master mill supervision method and the mathematical model
meant to generate the rolling schedule.
[0037] In detail, figure 1 illustrates the routine in charge of the activation of the SETPRE
function of the mathematical model. This function is activated before the rolling
of a coil begins and generates a "preliminary" rolling schedule.
[0038] Activation can be manual by the operator, by means of a suitable button which can
be selected by means of an on-screen page, or automatic, when a coil to be rolled
is identified by means of a suitable bar code reader which reads the bar code applied
to the coil to be rolled.
[0039] The preliminary schedule contains all the preset information for the mill for all
the passes required to reduce the gauge of the material to its intended final value.
[0040] In detail, after an initial step 1, control is transferred to a step 2 during which
the routine waits for the start command from the interface of the mathematical model
or from the bar code reader; the step 3 includes reading the code of the coil from
the real-time database; the step 4 provides for the retrieval of the material data
related to the coil to be rolled from the permanent database; the step 5 provides
for the retrieval from the database of the information related to the characteristics
of the coil to be rolled; the step 6 provides for the retrieval from the database
of the data related to the process constraints of the strip to be rolled, as a function
of the type of strip; the step 7 provides for the reading of information related to
the current status of the mill, generated by the CYCLIC function, from the real-time
database; the step 8 provides for a reset of the data for the rolling schedule, of
the information generated by a mathematical model during the execution of the various
routines that compose the various functions, and of the modifications that the operator
may have made to the schedule generated by the mathematical model; the subsequent
step 9 is a call to the SETPRE function of the mathematical model. The subsequent
step 10 is a step for verifying the information generated by a mathematical model;
if the check is negative, step 11, an error is sent to the interface means of the
mathematical model and control is transferred to a step 12 for storing the data generated
by the mathematical model in the database. Otherwise, if the check performed in step
10 is positive, control is transferred to a step 13, which stores the data generated
by the SETPRE function, that is to say, essentially data for the rolling schedule,
in the database.
[0041] Reference is now made to figure 2 to illustrate the activation routine for the function
of the mathematical model previously referenced by the name SETUP. This function is
activated before each rolling pass begins and updates the rolling schedule processed
earlier by the SETPRE function of the model for the coil currently being processed.
[0042] The function updates the preset information only for one rolling pass, taking into
account the current situation of the mill.
[0043] Activation occurs automatically according to various events which can occur during
the rolling process:
the rolling of a coil is about to begin and therefore the SETUP function is called
to generate the updating of the schedule of the first rolling pass;
the speed reduction at the end of a pass begins: the SETUP function is called to generate
the updating of the schedule for the next rolling pass;
five-minute timer: five minutes have elapsed since the end of a rolling pass and the
rolling of the next pass has not yet resumed: in this case, the SETUP function is
called to calculate a new update of the schedule for the current rolling pass.
[0044] In figure 2, an initial step 14 is followed by a step 15 in which the routine waits
for one second. The subsequent step 16 is a checking step, during which a signal SYNC,
which indicates an interaction between different processes (that is to say, one process
can report to another process that a given situation has occurred, thus conditioning
its execution), is checked. In this case, the signal SYNC checks whether a signal
for starting the first rolling pass or for ending the rolling pass has been received
or whether a five-minute timer expiration signal has been received. If the result
is negative, the routine returns to step 15, otherwise it moves on to a step 17 which
checks whether the situation is the rolling pass end situation. If the result is positive,
the routine moves on to a step 18, during which the material data are read from the
real-time database; this step is followed by the step 19, during which the rolling
pass counter is increased by one, and by a step 20, which checks whether the start
of a first rolling pass is occurring. If the result is negative, control is transferred
from step 17 directly to this step 20.
[0045] If the result of step 20 is positive, the routine moves on to a step 21, during which
the code of the coil being rolled is read from the real-time database. The step 21
is followed by a step 21a, during which the code of the steel of the strip of the
coil to be rolled is read from the real-time database; this step is followed by a
step 22, during which the rolling schedule, calculated by the SETPRE function of the
mathematical model, is extracted from the database.
[0046] A subsequent step 23 retrieves from the database information related to the characteristics
of the coil to be rolled or currently being rolled; material data, that is to say,
data related to the characteristics of the steels rolled in the mill; and data related
to constraints affecting the rolling mill as a function of the characteristics of
the strip being rolled. These constraints relate for example to gauge reduction constraints,
temperature constraints, speed constraints, tension constraints, roller roughness
constraints and the like.
[0047] The next step 24 sets the rolling pass counter to 1 and the next step 25 reads from
the real-time database data related to the configuration of the mill; data related
to the current status of the mill; the configuration parameters of the mathematical
model; and the data updated manually by the user for the rolling schedule.
[0048] The next step 26 resets the reliability data, that is to say, the information of
various kinds generated by the mathematical model during the executions of the various
routines that compose the various functions.
[0049] The step 27 instead updates the information concerning the characteristics of the
coil to be rolled or currently being rolled with the status of the actual process.
[0050] The next step 28 calls the SETUP function of the mathematical model, and the next
step 29 checks the reliability data, that is to say, the messages generated by the
mathematical model during the execution of the various routines. If the check yields
a negative result, control is transferred to a step 30, which sends a mathematical
model error signal to a lower mill automation level. Control is then transferred from
step 30 to step 31, which deactivates the mathematical model, and then returns to
step 15.
[0051] Considering step 20 again, if the check performed in said step is negative, control
is transferred directly to step 25.
[0052] If the check of step 29 is positive, control is instead transferred from said step
29 to a step 32, which checks whether the transfer of the schedule update to the lower
level is enabled. If the result is positive, control is transferred to a step 33,
which sends the updated schedule to the lower automation level of the mill, and then
control is transferred to a step 34, in which the data generated by the SETUP function,
that is to say, data for the rolling schedule, are written to the real-time database.
[0053] During step 32, if the result is negative control is transferred directly to said
step 34.
[0054] Control is then transferred from step 34 to a step 35, in which the data of the schedule
are stored in the database; then control is transferred to a step 36, in which the
reliability data are stored in the same database.
[0055] Figure 3 illustrates the activation of the mathematical model function CYCLIC. This
function is activated every 10 seconds and its main task is to continuously monitor
the status of the mill in order to analyze a short-term adaptation of parameters related
to the rollers of the mill (wear, roughness and temperature) and to preprocess information
which will be used at the end of the rolling pass by the ADAPT function. Activation
is automatic every 10 seconds.
[0056] In particular, the routine of figure 3 begins with the startup step 37, which is
followed by a step 38, which resets the data related to the current status of the
mill and the data exchanged between the CYCLIC and ADAPT functions of the mathematical
model on the real-time database.
[0057] The next step 39 retrieves from the database the configuration parameters of the
mathematical model and the data related to the configuration of the mill.
[0058] The next step 40 writes the parameters of the mathematical model and the data of
the mill thus obtained from the database to the real-time database.
[0059] Then, step 41, the routine waits for one second and then moves on to the step 42,
which reads the data related to the current status of the rolling process from the
real-time database; this is followed by a step 43, during which these process data
are accumulated, and by a step 44, during which reception of the SYNC signal, indicating
the end of the execution of the ADAPT function, is checked for.
[0060] If this check is positive, control is transferred to a step 45, during which data
related to the motors, to friction and to the material to be rolled are retrieved
from the real-time database; this is followed by a step 46, during which reception
of a signal SYNC, indicating a speed reduction of the rolling pass, is checked for.
[0061] If the result to the step 44 is negative, control is transferred directly to said
step 46.
[0062] If the result is positive, control is transferred from step 46 to a step 47, during
which the data related to the current status of the mill, the data related to the
configuration of the mill and the data related to the exchange between the CYCLIC
and ADAPT functions are written to the real-time database.
[0063] This is followed by the step 48, during which a start signal is sent to the routine
for activating the ADAPT function.
[0064] This step is followed by a step 49, during which reception of a signal SYNC, indicating
a request for housing configuration data for positioning the line for the transit
of the strip to be rolled, is checked for.
[0065] If the result is positive, control is transferred to a step 50, during which the
housing configuration data for positioning the line for the transit of the strip to
be rolled are sent to the lowest mill automation level; then control is transferred
to a step 51, which checks whether 10 seconds have elapsed.
[0066] In step 49, if the result is negative, control is transferred to step 51; in step
51, if the result is negative, control returns to step 41.
[0067] In step 51, if the result is positive, control is transferred to step 52, which checks
for the reception of the signal SYNC, indicating a change of the rollers.
[0068] If the result is positive, the routine moves on to step 53, which retrieves from
the database the data related to the rollers; then control is transferred to a step
54, during which the data of the rollers are written to the real-time database; then
an average for the process data is computed in step 55.
[0069] In step 52, if the result is negative, the routine moves on directly to said step
55.
[0070] In step 55, the routine moves on to a step 56, during which process data are written
to the real-time database, and then on to a step 57, during which the code of the
coil being rolled is read from the real-time database.
[0071] This is followed by a step 58, which checks whether the coil being rolled has changed.
If the result is positive, the routine moves on to step 59, which retrieves from the
database the information related to the characteristics of the coil that is to be
rolled or is currently being rolled.
[0072] This is followed by a step 60, during which these characteristics are written to
the real-time database, and by a step 61, during which a series of tables is retrieved
from the database; said tables, according to the characteristics of the rolled strip,
provide the mathematical model with information regarding the constraints which the
rolling mill must comply with.
[0073] The next step 62 checks whether the code of the steel being rolled has changed or
not.
[0074] If the result is positive, the routine moves on to a step 63, during which the data
related to the material are retrieved from the database. This is followed by a step
64, during which said data are written to the real-time database.
[0075] The next step 65 reads from the real-time database the configuration parameters of
the mathematical model, the information generated by the SETPRE and SETUP functions
for the rolling schedule to be sent to the lower mill supervision level, and data
related to the configuration of the mill.
[0076] In step 58, if the result is negative, control is transferred directly to said step
65; likewise, in step 62, if the result is negative, control is transferred to said
step 65 again.
[0077] This is followed by a step 66, during which the reliability data are reset, followed
by a step 67, in which the routine calls the CYCLIC function of the mathematical model.
[0078] The next step 68 stores reliability data in the database and the step 69 checks the
reliability data. If the check is negative, the routine returns to step 41.
[0079] If the check is positive, control is transferred to a step 70, which checks whether
30 seconds have elapsed. If the result is negative, the routine returns to step 41,
whilst if the result is positive, the routine moves on to a step 71, in which the
dynamic data of the rollers are stored; the routine then returns to step 41.
[0080] With reference now to figure 4, a routine is described which is in charge of the
activation of the ADAPT function of the mathematical model. This function is activated
at the end of each rolling pass and its main task is to adapt the parameters related
to the materials, to the mill, to tables related to constraints that the mill must
meet, et cetera. Activation is automatic at the end of each rolling pass.
[0081] This routine begins with a startup step 72, followed by a step 73 during which the
routine waits for one second.
[0082] This is then followed by a step 74, which checks whether the signal SYNC has been
received by the CYCLIC function of the mathematical model.
[0083] If the result is negative, control is transferred to a step 75, which checks whether
the signal SYNC has been received by the interface means of the mathematical model.
If the result is negative, the routine returns to step 73, whilst if the result is
positive, the routine moves on to a step 76, during which the parameters of the mathematical
model and the data of the mill are retrieved from the database; this is followed by
a step 77, which writes the parameters of the mathematical model and the mill data
to the real-time database and then returns to the step 73.
[0084] In step 74, if the result is positive, the routine moves on to a step 78, which checks
whether the SYNC signal, indicating the last rolling pass, has been received. If the
result is negative, the routine moves on to a step 79, which checks whether there
is an interlock between the ADAPT and SETUP functions of the mathematical model. If
the result is negative, the routine then moves on to a step 80, which sends the SYNC
signal to the SETUP function of the mathematical model, and then on to a step 81,
during which the code of the coil being rolled is extracted from the real-time database.
In step 78, if the result is positive, control is transferred directly to this step
81; likewise, in step 79, if the result is positive, control is again transferred
to said step 81.
[0085] Step 81 is followed by a step 82, during which the data related to the constraints
that the mill must meet and the parameters of the mathematical model are extracted
from the database.
[0086] A step 83 then follows during which the data related to the mill, the material, information
related to the current status of the mill, the data related to the exchange between
the CYCLIC and ADAPT functions, information related to the characteristics of the
coil that is to be rolled or is currently being rolled and the data generated by the
SETPRE and SETUP functions are read from the real-time database.
[0087] A step 84 then follows in which the reliability data are reset; this is followed
by a step 85, during which the routine calls the ADAPT function of the mathematical
model.
[0088] The next step 86 stores the reliability data in the database and the step 87 checks
the reliability data.
[0089] If the check has a negative result, the routine moves on to a step 88, during which
the parameters of the mathematical model are stored in the database; this is followed
by a step 89, which checks whether a last rolling pass is being performed and whether
the SETUP function has already been called.
[0090] If the result is negative, the routine returns to step 73; if the result is positive,
control is transferred to a step 90, during which the SYNC signal is sent to the routine
for activating the SETUP function of the mathematical model in order to activate said
function. The routine returns from step 90 to step 73.
[0091] If the result is instead positive, the routine moves on from step 87 to a step 91
which writes to the real-time database the data related to the mill, to the material
and to the parameters of the mathematical model.
[0092] This is followed by a step 92, during which the signal SYNC is sent to the routine
of figure 3 to indicate that the process performed by the ADAPT function has ended.
[0093] This is followed by a step 93, which checks whether a last rolling pass is being
performed and whether the SETUP function has already been called.
[0094] If the result is negative, control is transferred to a step 94, which sends the signal
SYNC to the routine of figure 2 in order to start the SETUP function of the mathematical
model.
[0095] This is followed by a step 95, during which the data of the parameters of the mathematical
model are stored in the database. In step 93, if the result is positive, control is
transferred directly to this step 95.
[0096] This is then followed by a step 96, which updates in the database the data related
to the motors, to friction and to the material; this is then followed by a step 97,
which checks whether a last rolling pass is being performed. If the result is negative,
the routine returns to step 73; if the result is positive, the routine moves on to
a step 98, during which the tables related to the constraints that the mill must meet
according to the characteristics of the material are updated in the database.
[0097] The routine then again returns from said step to the step 73.
[0098] With reference now to figure 5, a routine is described which is in charge of the
activation of the SETPRE function of the mathematical model. This function is activated
again after generating the preliminary schedule if the operator wishes to make changes
to said schedule. The model compares the original schedule provided by the SETPRE
function and the schedule modified by the operator and is capable of providing a new
schedule, taking into account the recommendations of the operator.
[0099] Activation is manual on the part of the operator after he has modified the schedule.
[0100] This routine begins with a startup step 99, which is followed by a step 100 which
waits for startup performed by the interface means of the mathematical model, that
is to say, waits for activation by the operator.
[0101] The next step 101 reads the code of the coil and the code of the schedule from the
real-time database.
[0102] The step 102 extracts from the database the data related to the material and the
step 103 extracts from the database the characteristics of the coil to be rolled or
currently being rolled. The step 104 extracts, according to the characteristics of
the rolled strip, the constraints with which the mill must comply. The step 105 extracts
the data calculated by the function 73 and the next step 106 reads the data related
the mill, to the current status of the mill and the parameters of the model from the
real-time database.
[0103] The next step 107 resets the data generated by the SETPRE and SETUP functions and
the reliability data.
[0104] The step 108 then extracts a manual modification of the schedule of the database,
and the step 109 calls the SETPRE function of the mathematical model.
[0105] The next step 110 checks the reliability data; if the check is negative, control
is transferred to the step 111, during which an error is returned to the interface
means of the mathematical model; this is followed by a step 114 for storing the reliability
data in the database.
[0106] If instead the check is positive, the routine moves on to a step 112, which stores
the information generated by the SETPRE function in the database; this is followed
by a step 113, during which the manually updated data are written to the real-time
database.
[0107] Control is then transferred from step 113 to the above described step 114 and from
there the routine returns to step 100.
[0108] In practice it has been found that the method according to the invention fully achieves
the intended aim, since it allows to interact on-line with the mathematical model
that creates the rolling schedule, keeping under control both the data related to
the mill and the data related to the material to be rolled, in addition to the data
related to any changes made by the user during rolling.
[0109] The method thus conceived is susceptible of numerous modifications and variations,
all of which are within the scope of the inventive concept; all the details may furthermore
be replaced with other technically equivalent elements.