Method for setting operating conditions for continuous hot rolling facilities

A continuous hot rolling method includes setting operating conditions (OC) for hot rolling facilities, regarding rolled material for which endless rolling was planned, in which a preceding piece of material and a subsequent piece of material are joined to each other, to batch rolling, in which rolling is performed without joining the preceding piece of material and subsequent piece of material to each other, or setting of changes from batch rolling to endless rolling. Changes can be speedily and accurately made, so that operating problems, or defective coils due to inaccurate changes in settings or delays in changing the settings can be prevented. Both the operating conditions (OCIe) for endless rolling and the operating conditions (OCIb) for batch rolling are predetermined, and the operating conditions (OCe,OCb) for the facilities at various positions on the hot rolling line are determined for both endless rolling and for batch rolling.

BACKGROUND OF THE INVENTION
 1. Field of Invention
 This invention relates to a hot rolling method in which finish rolling is
 continuously performed. This invention particularly relates to a method
 for setting operating conditions for hot rolling facilities, which is
 capable of speedily and accurately performing setting changes regarding
 rolled material for which was planned endless rolling, wherein a preceding
 piece of material and a subsequent piece of material are joined each other
 at the entering side of a finishing mill, to batch rolling, wherein
 rolling is performed without joining the preceding piece of material and
 subsequent piece of material, or performing setting changes from batch
 rolling to endless rolling.
 2. Description of Related Art
 Conventionally, in hot rolling process, slabs are heated in a reheating
 furnace, and the slab extracted form the reheating furnace is subjected to
 rough rolling, and then finish rolling is performed for each roughed sheet
 bar, i.e., a batch rolling operation has been performed to manufacture
 steel strips, such as thin articles. However, in recent years, so-called
 endless rolling operation has been performed to manufacture steel strips,
 such as thin articles. In these operations, the tail end (rolled) of a
 preceding material is joined to the head end (rolled) of a subsequent
 material between a roughing mill and finishing mill, which is repeatedly
 performed so as to continuously perform finish rolling of the preceding
 material and the subsequent material.
 FIG. 4 schematically shows an apparatus 10 for endless rolling. During the
 endless rolling operation, the tail end 12 of the preceding (downstream)
 material 14 and the head end 16 of the subsequent (upstream) material 18
 are joined to each other at a sheet bar joining machine 30 provided
 between a 3-stand roughing mill 20, for example, and a 7-stand finishing
 mill 40, for example, so that finish rolling is continuously performed
 with the preceding material 14 and the subsequent material 18 being
 joined. A strip shear 50 for cutting the rolled material is provided
 downstream from the finishing mill 40, and multiple coilers 60 (two are
 shown) are provided downstream from the strip shear 50, so that the rolled
 material is subjected to finish rolling in the state in which the
 preceding material 14 and the subsequent material 18 are joined and is cut
 by the strip shear 50 into lengths which the coilers 60 can take up, with
 the rolled material preceding the cutting point, and the rolled material
 following the cutting point, being taken up on separate respective
 coilers.
 Continuous finish rolling can be performed in the state in which the
 preceding material 14 and the subsequent material 18 are joined to each
 other by such an endless rolling operation, so there are no inconsistent
 portions at the head and tail ends in the finish rolling of individual
 sheet bars as with batch rolling, and stable rolling can be performed over
 the entire length of the rolled material. Thus, this arrangement is
 suitable for the rolling of rolled material for which the passage of
 inconsistent portions is difficult, such as with thin articles.
 Operation condition (OC) settings for the facilities within such a hot
 rolling line are made by computer, as shown in FIG. 5. That is, for each
 slab (material to be rolled), product information (PI) (slab thickness,
 slab width, product thickness, product width, specifications, etc.) are
 inputted to an on-line computer 70, the on-line computer 70 sets the
 operating conditions (OCI) (tension between stands in the finishing mill,
 coiling tension, rolling speed, rolling temperature, draft schedule,
 conditions for cooling rolled material, etc.) for initial settings for the
 hot rolling facilities based on the slab information, and these operating
 conditions (OCI) for initial settings are sent to a process computer 72.
 Once the slab is placed on the rolling line, the process computer 72. Once
 the slab is placed on the rolling line, the process computer 72 reads in
 rolled material information (IRM), such as detection values (temperature,
 plate thickness, plate width, etc.) from detectors positioned at various
 locations on the rolling line. In FIG. 5, these detectors are the detector
 24 at the exit side of the roughing mill 20, the detector 32 at the exit
 side of the sheet bar joining machine 30, and the detector 44 at the exit
 side of the finishing mill 40. The process computer 72 also reads in
 actual operating data, including the rolling load at the drafting devices
 22 of the roughing mill 20 and at the drafting devices 42 of the finishing
 mill 40, of the facilities for continuous hot rolling. In the embodiment
 shown in FIG. 5, these facilities include the roughing mill 20, sheet bar
 joining machine 30, finishing mill 40, strip shear 50 and coiler 60. The
 process computer 72 calculates the operating conditions (OC) for the
 facilities downstream from the current position of the rolled material, so
 that the rolled material is rolled to the product specifications provided
 to the on-line computer 70, based on such rolled material information.
 Then, operating conditions signals based on the calculation results are
 sent to the facilities, thereby running these facilities.
 For example, for batch rolling operations, the calculation of the operating
 conditions (OC) of the finishing mill 40 by the process computer 72 is
 performed as follows. At the stage that the rough rolling is completed at
 the roughing mill 20, the rolled material information (IRM) relating to
 the dimensions and temperature of the roughed sheet bar is detected by the
 detector 24 at the exit side of the roughing mill 20, or is calculated
 based on the actual operating data from the roughing mill 20, and
 operating conditions (OC) for the finishing mill 40 (load for each stand,
 mill gaps, circumferential speed for the reduction rollers, etc.) such
 that the finish rolling is executed under the finishing operating
 conditions (OC) sent from the on-line computer 70, based on the rolled
 material information.
 On the other hand, in the endless rolling operation, the process computer
 72 calculates the operating conditions (OC) for the finishing mill 40
 regarding the subsequent material 18, after the preceding material 14 is
 joined to the subsequent material 18 at the sheet bar joining machine 30.
 However, in some cases, rolled material for which endless rolling was
 planned must be switched to batch rolling, due to reasons such as
 operating problems occurring, e.g., malfunctioning of the sheet bar
 joining machine 30.
 In this case, the operating conditions (OC) settings for the finishing mill
 40 regarding the rolled material for which endless rolling was initially
 planned are based on the operating conditions (OC) provided from the
 on-line computer 70 assuming that endless rolling is to be performed.
 Accordingly, in the event that batch rolling is performed with the setting
 values for the operating conditions (OC) for endless rolling maintained as
 they are, the target product dimensions cannot be attained. Accordingly,
 in the event of performing batch rolling for rolled material for which
 endless rolling was initially planned, the operating conditions (OC) for
 the finishing mill have been manually changed by the operator to carryout
 the batch rolling.
 However, when such setting changes in operating conditions (OC) are made by
 manually, not only are the operations extremely complicated, they must
 also be carried out in the short time period between the tail end 12 of
 the preceding material 14 completely passing through the finishing mill
 40, and the finishing mill 40 biting the head end 16 of the subsequent
 material 18. Accordingly, there have been problems, such as changes in the
 settings of the operating conditions (OC) not being made accurately, or
 not being made in time, resulting in operating problems, or in not
 attaining the target rolled product dimensions, and consequently producing
 defective coils.
 Japanese Unexamined Patent Publication No. 6-297018 discloses an
 arrangement in which material fracture detection is performed for the
 connection of materials when performing continuous hot rolling, and based
 on the detection of material fracture, the transport speed of the material
 upstream of the fracture point is temporarily reduced so as to create a
 spacing between the material upstream of the fracture point and the
 material downstream of the fracture point, and the settings for the
 finishing mill are switched from the endless rolling setting method to the
 batch rolling setting method, thereby eliminating miss rolling at the time
 of biting with the finishing mill. However, this Publication does not
 disclose any method for switching from endless rolling to batch rolling in
 the event that some sort of anomaly occurs before, or at the time of,
 joining the materials.
 The above description pertains to problems regarding the finishing mill 40
 in switching material to be rolled, for which endless rolling had been
 planned, to batch rolling. However, there are similar problems for
 facilities other than the finishing mill 40, such as the rolled material
 cooling equipment (not shown) or coilers 60, for example, provided
 downstream from the finishing mill 40.
 SUMMARY OF THE INVENTION
 This invention has been made in order to solve the above-described
 conventional problems. It is an object of this invention to speedily and
 accurately perform setting changes for the operating conditions of the
 facilities for hot rolling, regarding changing rolled material, for which
 endless rolling had been planned, from endless rolling to batch rolling,
 or regarding changing rolled material, for which batch rolling had been
 planned, from batch rolling to endless rolling.
 This invention solves the above-described problems by providing a method
 for setting operating conditions (OC) for hot rolling material, in which
 product information (PI) for the material to be rolled (specifications for
 the material to be rolled, slab dimensions, product thickness, product
 width, etc.) is inputted, the operating conditions (OCI) for initial
 settings of the facilities for each material to be rolled are
 predetermined based on the product information (PI) for the material to be
 rolled, then the material to be rolled is placed on the hot rolling line,
 information (IRM) of the rolled material being rolled, such as thickness,
 width, temperature, etc., is detected at various positions on the hot
 rolling line, and operating conditions (OC) of facilities downstream from
 the position at which the information (IRM) for the rolled material is
 detected are calculated based on the information detection values of the
 rolled material and the operating conditions (OCI) for the initial
 settings. Both the operating conditions (OCe) for endless rolling, and the
 operating conditions (OCb) for batch rolling, in which rolling is
 performed without joining a preceding material and a subsequent material
 to each other, are predetermined, and sent to a device, such as, for
 example, an on-line computer.
 According to this invention, both the operating conditions (OCIe) for the
 initial settings for endless rolling and the operating conditions (OCIb)
 for the initial settings for batch rolling, regarding a material to be
 rolled for which endless rolling was planned, e.g., a slab, are determined
 by a device, such as, for example, an on-line computer. Then, if execution
 of endless rolling becomes impossible, a device, such as a process
 computer, for example, calculates the operating conditions (OCb) for batch
 rolling for the facilities, based on the already-determined operating
 conditions (OCIb) for the initial settings for batch rolling. Accordingly,
 even if the plans for endless rolling need to be suddenly changed to batch
 rolling, there is no need for manually changing the settings of the
 operating conditions. Consequently, complicated tasks associated with the
 setting changes of the operating conditions are eliminated, and also
 operating problems and defective coils, which are related to mistakes and
 delays in changing settings, can be prevented.
 Further, according to this invention, calculations for the operating
 conditions (OC) for the facilities are performed regarding both operating
 conditions (OCe) for endless rolling based on the information (IRM) of the
 rolled material and the operating conditions (OCIe) for the initial
 settings for endless rolling, and operating conditions (OCb) for batch
 rolling based on the information (IRM) of the rolled material and the
 operating conditions (OCIb) for the initial settings for batch rolling.
 In this case, both the operating conditions (OCIe) for the initial settings
 for endless rolling and the operating conditions (OCIb) for the initial
 settings for batch rolling, regarding a material to be rolled for which
 endless rolling was planned, e.g., a slab, are determined by the on-line
 computer, for example. Further, when the material being rolled reaches a
 certain position in the facilities on the rolling line, the process
 computer, for example, calculates both the operating conditions (OCe) for
 endless rolling and the operating conditions (OCb) for batch rolling, at
 the time of calculating the operating conditions (OC) for the facilities
 downstream of the certain position. In the event that endless rolling is
 to be performed as planned, the facilities are run under the operating
 conditions (OCe) for endless rolling. On the other hand, even in the event
 of switching from endless rolling to batch rolling, the already-calculated
 batch rolling operating conditions (OCb) are used, so that the operating
 conditions (OC) of the facilities can be switched to those for batch
 rolling in a short period of time.
 Also, this invention is capable of setting operating conditions (OCe,OCb)
 for endless rolling or batch rolling regarding facilities upstream of the
 sheet bar joining machine (such as a reheating furnace or a roughing
 mill), so that switching between endless rolling and batch rolling can be
 carried out in a more flexible and smoother manner. In addition, the
 complicated operations of operator-based switching can be eliminated.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
 An embodiment of this invention applied to the control device shown in FIG.
 5 will now be described in detail, with reference to the drawings. The
 embodiment of the invention is arranged such that the operating conditions
 (OCIe) for initial settings for the facilities for endless rolling, and
 the operating conditions (OCIb) for initial settings for the facilities
 for batch rolling, are set in the on-line computer 70, for all slabs. For
 example, as shown in FIG. 1, the operating conditions (OCIe) for the
 initial settings for the facilities for endless rolling and the operating
 conditions (OCIb) for the initial settings for the facilities for batch
 rolling can be provided in records in the on-line computer 70 for product
 information (PI). The product information (PI) can include, for example,
 slab thickness, slab width, hots rolling command thickness (product
 thickness following hot rolling), hot rolling command width (product width
 following hot rolling), and specifications. Operating conditions (OC)
 include, for example, settings for the tension between the stands of the
 finishing mill 40 (tension between finishing stands), settings for tension
 between the coilers 60 and the finishing mill 40 (coiling tension),
 rolling speed, and the like.
 Then, as shown in the processing procedures in FIG. 2, the operating
 conditions (OCIb) for initial settings for the facilities for batch
 rolling, and the operating conditions (OCIe) for initial settings for the
 facilities for endless rolling, are provided for all slabs (step 100).
 Also, regarding slabs for which endless rolling is planned, an endless
 rolling command is input to the on-line computer 70, so that the on-line
 computer 70 recognizes whether or not to perform endless rolling for each
 slab (step 110).
 Next, once the product information (PI), such as slab dimensions, hot
 rolling command thickness, hot rolling command width, and specifications
 are input to the on-line computer 70 (step 120), the on-line computer 70
 determines the operating conditions (OCI) for initial settings
 corresponding to the slab thickness, slab width, hot rolling command
 thickness, hot rolling command width, and specifications in the record,
 and sends the operating conditions to the process computer 72 (step 130).
 After the slab is placed on the hot rolling line (step 140), the process
 computer 72 calculates the operating conditions (OC) of the facilities
 downstream from the current position of the rolled material, at each
 position along the hot rolling line (step 150). At this time, in the event
 that endless rolling is planned for the slab, both the operating
 conditions (OCIe) for the initial settings for facilities for endless
 rolling, and the operating conditions (OCIb) for the initial settings for
 facilities for batch rolling, have been sent from the on-line computer 70
 to the process computer 72, so that the process computer 72 calculates the
 operating conditions (OCe,OCb) for both endless rolling and for batch
 rolling.
 The following is a description of an exemplary embodiment of calculating
 the operating conditions (OCe) for finish rolling for material regarding
 which endless rolling is planned.
 Regarding a slab for which the endless rolling command has been input to
 the on-line computer 70 (step 160), the process computer 72 calculates the
 operating conditions (OCe) of the sheet bar joining machine 30 following
 completion of rough rolling, and the sheet bar joining machine 30 joins
 the subsequent material to the preceding material under the above
 operating conditions. When the joining is completed, the process computer
 72 calculates the operating conditions (OCe) of the finishing mill 40 for
 endless rolling, and the finishing mill 40 is operated under the operating
 conditions calculated at this point (step 170).
 With this invention, the operating conditions (OCIb) for the initial
 settings for facilities for batch rolling have also been sent from the
 on-line computer 70 for material for which endless rolling is planned, so
 that calculations are also made for setting the operating conditions (OCb)
 of the finishing mill 40 if batch rolling is to be performed, based on the
 operating conditions (OCIb) for the initial settings for facilities for
 batch rolling and the rolled material information (IRM). Specifically,
 when rough rolling is completed, the process computer 72 makes
 calculations of settings for operating conditions (OCe) for performing
 endless rolling, wherein the sheet bar joining machine 30 is run, and
 following joining, the finishing mill 40 is run under the operating
 conditions (OCe) of endless rolling, and also makes calculations of
 settings for operating conditions (OCb) for performing batch rolling, in
 which the sheet bar joining machine 30 is not run, and the finishing mill
 40 is run under the operating conditions (OCb) of batch rolling.
 Accordingly, even if endless rolling becomes impossible at any point
 before joining due to malfunctioning of the sheet bar joining machine 30
 or the like, the operator or a sensor detecting the anomaly inputting an
 endless rolling abort signal to the process computer 72 (step 180) causes
 the process computer 72 to run the facilities downstream of the roughing
 mill based on the calculation results for the settings for the operating
 conditions for batch rolling, performed at the point that roughing milling
 was completed (step 190).
 For endless rolling in general, articles for which batch rolling is
 difficult, such as articles with a thin hot rolling command thickness, are
 often rolled. Accordingly, in the event of changing from endless rolling
 to batch rolling, there are cases where the article cannot be manufactured
 at the hot rolling command thickness, which was planned for endless
 rolling. In such cases, a commonly-employed thickness changing function (a
 function wherein, in the event that the operator selects a thickness to
 change to, calculations are made for the operating conditions (OC) for
 automatically rolling to that thickness) can be used for the operator to
 change the hot rolling command thickness at the time of changing to batch
 rolling.
 The above description pertains to an embodiment applied to calculations
 made at the time following roughing milling to starting finish rolling,
 i.e., calculating the operating conditions (OC) of the sheet bar joining
 machine 30 and finishing mill 40. However, this invention preferably can
 be applied to all facilities within the continuous hot rolling line and
 not only to the sheet bar joining machine 30 and finishing mill 40. For
 example, before performing rough rolling of the rolled material for which
 endless rolling is planned, both the operating conditions (OCe) of the
 roughing mill for endless rolling and the operating conditions (OCb) of
 the roughing mill for batch rolling are preferably calculated.
 Particularly, for facilities wherein the operating conditions (OCe,OCb)
 for endless rolling and for batch rolling differ greatly from each other,
 it is necessary to calculate the operating conditions (OCe,OCb) for both
 endless rolling and batch rolling.
 FIG. 3 illustrates the transition of the rate of problems occurring at the
 time of aborting endless rolling (denoted by circles in the chart), and
 the down time (denoted by triangles). Here, the rate of occurrences of
 problems means the number of times that finish rolling could not be
 performed, or the process did not proceed to correct coiling due to
 deformations following finish rolling or other causes, as to the number of
 times that endless milling was aborted. Also, the down time means the
 amount of time that the rolling line was shut down due to problems
 accompanying aborting endless milling.
 The method for setting operating conditions (OC) according to this
 invention (wherein, as described above, both the operating conditions
 (OCIe) for the initial settings for facilities for endless rolling and the
 operating conditions (OCIb) for the initial settings for facilities for
 batch rolling are determined by an on-line computer, and a process
 computer calculates both the operating conditions (OCe) for endless
 rolling and the operating conditions (OCb) for batch rolling when
 calculating the operating conditions (OC) for the facilities at various
 positions on the hot rolling line) was started up in October, and as can
 be clearly understood from FIG. 3, the occurrence of problems accompanying
 the abortion of endless rolling became practically non-existent following
 October, as well as the down time associated with such problems being
 eliminated.
 Thus, setting changes can be speedily and accurately made for operating
 conditions (OC) for the facilities regarding rolled material, for which
 endless rolling was planned, from endless rolling to batch rolling, or
 from batch rolling to endless rolling, so that operating problems or
 defective coils due to inaccurate settings for the operating conditions
 (OC) for the facilities, or delays in changing the settings, can be
 prevented. This invention can also set operating conditions (OCe,OCb) for
 endless rolling or batch rolling for facilities upstream of the sheet bar
 joining machine (reheating furnace, roughing mill, etc.) as well, so that
 the operations of switching between endless rolling and batch rolling can
 be carried out in a more flexible and smoother manner. Also, the
 complicated operations of operator-based switching can be eliminated.