Patent Application
20210039148
The present invention relates to a rolling mill that rolls a workpiece, and a method for setting the rolling mill.
In a hot rolling process, for example, zigzagging of a steel plate occurs as a phenomenon that is the cause of rolling trouble. A thrust force that is generated at a minute cross (also referred to as “roll skew”) between rolls of a rolling apparatus is one cause of zigzagging of a steel plate, and it is difficult to directly measure such a thrust force. Therefore, in the past it has been proposed to measure a thrust counterforce that is detected as a counterforce that is the total value of thrust forces generated between rolls or a roll skew angle, and identify the thrust force generated between rolls based on the thrust counterforce or the roll skew angle and perform zigzagging control of the steel plate.
For example, Patent Document 1 discloses a plate rolling method which measures a thrust counterforce in the axial direction of a roll and a load in a vertical direction, determines either one of, or both of, a reduction position zero point and deformation properties of the rolling mill, and sets the reduction position at the time of rolling execution and controls rolling. Further, Patent Document 2 discloses a zigzagging control method that calculates a thrust force generated at a roll based on an inter-roll minute cross angle (skew angle) that is measured using a distance sensor provided inside a rolling mill and, based on the thrust force, calculates a differential load component that is a cause of zigzagging based on a load measurement value in the vertical direction and performs reduction leveling control. In addition, Patent Document 3 discloses a cross-point correcting device which corrects a deviation in a point (cross point) at which the central axes of upper and lower rolls cross in the horizontal direction in a pair cross rolling mill. The apparatus includes an actuator that absorbs play that arises between a crosshead and roll chocks, and a detector that detects roll chock positions, and corrects a deviation in the cross point based on the roll chock positions.
Further, Patent Document 4 discloses a method for controlling a rolling mill that detects a load difference between the drive side and the work side, and by estimating a differential load caused by thrust during rolling when controlling zigzagging of a rolled material by independently controlling reduction positions on the drive side and on the work side based on the detected load difference, separates a differential load during rolling into a load that is attributable to zigzagging of the rolled material and a load that is attributable to thrust, and controls reduction positions on the drive side and the work side based on these separated differential loads.
Patent Document 1: JP3499107B
Patent Document 2: JP2014-4599A
Patent Document 3: JP8-294713A
Patent Document 4: JP4962334B
However, according to the technique disclosed in Patent Document 1, although it is necessary to perform measurement of the thrust counterforce of rolls other than a backup roll at a time of reduction position zero point adjustment and during rolling, in the case of measuring thrust counterforces during rolling, in some cases characteristics such as the working point of the thrust counterforce change depending on changes in the rolling conditions such as the rolling load, and asymmetric deformation that accompanies the thrust force cannot be correctly identified. Therefore, there is the possibility that reduction leveling control cannot be accurately performed.
Further, according to the technique disclosed in Patent Document 2, a roll skew angle is determined based on a distance in the horizontal direction of a roll that is measured by a distance sensor such as a vortex sensor. However, because a roll vibrates in the horizontal direction depending on the degree of machining precision such as the eccentricity or cylindricity of a roll body length portion, and chock positions in the horizontal direction fluctuate due to impact at the time of biting at the start of rolling and the like, it is difficult to accurately measure the horizontal displacement of a roll which is a factor that causes the generation of a thrust force. Furthermore, the coefficient of friction of a roll is constantly changing because the degree of roughness of a roll changes with time as the number of rolled workpieces increases. Therefore, calculation of a thrust force without identification of the coefficient of friction cannot be performed accurately based on only a roll skew angle measurement.
In addition, according to the technique disclosed in Patent Document 3, an inter-roll cross angle arises due to relative crossing of rolls, and since there is also looseness in roll bearings and the like, even if position control of each roll chock position is individually performed in the rolling direction, deviations in the relative positional relation between the rolls themselves are not eliminated. Consequently, thrust forces that are generated due to inter-roll cross angles cannot be eliminated.
Further, according to the technique disclosed in Patent Document 4, prior to rolling, in a state in which upper and lower rolls do not contact each other, a bending force is imparted while driving the rolls, and a differential load that is caused by thrust is estimated based on a thrust factor or a skew amount that is determined based on a load difference between the drive side and the work side that arises at such time. According to Patent Document 4, the thrust factor or skew amount is identified based on only measurement values in one rotational state of the upper and lower rolls. Therefore, in a case where there is a deviation in a zero point at a load detection apparatus or in a case where the influence of frictional resistance between the housing and roll chocks differs between left and right, there is a possibility that a left-right asymmetry error may arise between a measurement value on the drive side and a measurement value on the work side. In particular, in a case where the load level is small, such as in the case of a bending force load, the error in question can become a critical error with respect to identification of the thrust factor or the skew amount. Further, according to the technique disclosed in Patent Document 4, a thrust factor or a skew amount cannot be identified unless a coefficient of friction between rolls is applied.
In addition, according to Patent Document 4, it is assumed that a thrust counterforce of a backup roll acts along the axial center position of the roll, and a change in the position of the working point of the thrust counterforce is not taken into consideration. Usually, because the chocks of a backup roll are supported by a pressing-down device or the like, the position of the working point of a thrust counterforce is not always located along the axial center of the roll. Consequently, an error arises in an inter-roll thrust force that is determined based on a load difference between a vertical roll load on the drive side and a vertical roll load on the work side, and an error also arises in a thrust factor or a skew amount that is calculated based on the inter-roll thrust force.
The present invention has been made in view of the problems described above, and an objective of the present invention is to provide a novel and improved method for setting a rolling mill, and a rolling mill which are capable of reducing thrust forces generated between rolls and suppressing the occurrence of zigzagging and camber of a workpiece.
To solve the problems described above, according to one aspect of the present invention there is provided a method for setting a rolling mill, the rolling mill being a rolling mill of four-high or more that includes a plurality of rolls including at least a pair of work rolls and a pair of backup rolls supporting the work rolls, with a plurality of rolls provided on an upper side in a vertical direction with respect to a workpiece being taken as an upper roll assembly, a plurality of rolls provided on a lower side in the vertical direction with respect to the workpiece being taken as a lower roll assembly, and any one roll among the respective rolls that are arranged in the vertical direction being adopted as a reference roll, wherein the rolling mill includes: a torque measurement apparatus which measures a torque acting on the work rolls that is generated by driving of a motor that drives the work rolls; a vertical roll load measurement apparatus which is provided on a work side and a drive side on at least a lower side or an upper side of the rolling mill and which measures a vertical roll load in the vertical direction; a pressing apparatus which, with respect to at least roll chocks of the rolls other than the reference roll, is provided on either one of an entrance side and an exit side in a rolling direction, and which presses the roll chocks in a rolling direction of a workpiece; and a roll chock driving apparatus which, with respect to at least roll chocks of the rolls other than the reference roll, is provided so as to face the pressing apparatus in the rolling direction, and which moves the roll chocks in a rolling direction of a workpiece; the method for setting a rolling mill being executed before reduction position zero point adjustment or before starting rolling, and including a first process of: setting a roll gap between the work rolls in an open state, and with respect to each of the upper roll assembly and the lower roll assembly, in a roll assembly on a side on which the vertical roll load measurement apparatus is installed, measuring a torque acting on the work roll by means of the torque measurement apparatus, or measuring a vertical roll load in two different rotational states of the pair of work rolls on the work side and the drive side, respectively, by means of the vertical roll load measurement apparatus; in a roll assembly on a side on which the vertical roll load measurement apparatus is not installed, measuring a torque acting on the work roll by means of the torque measurement apparatus; and fixing a rolling direction position of roll chocks of the reference roll as a reference position, and moving roll chocks of the rolls other than the reference roll by means of the roll chock driving apparatus based on the torque or a vertical roll load difference that is a difference between a vertical roll load on the work side and a vertical roll load on the drive side, to thereby adjust positions of the roll chocks; and a second process of, after performing the first process, setting the work rolls in a kiss roll state, and measuring a vertical roll load in two different rotational states of the pair of work rolls on the work side and the drive side, respectively, by means of the vertical roll load measurement apparatus; and fixing a rolling direction position of roll chocks of the reference roll as a reference position, and moving the roll chocks of each roll of a roll assembly on an opposite side to the reference roll by means of the roll chock driving apparatus simultaneously and in a same direction while maintaining relative positions between the roll chocks so that the vertical roll load difference is within a predetermined allowable range, to thereby adjust positions of the roll chocks.
In this case, a roll located at a lowermost part or an uppermost part in the vertical direction among the plurality of rolls may be adopted as the reference roll.
Further, in the rolling mill of four-high, when the work rolls are independently driven by different motors, respectively, a configuration may be adopted in which: in the first process, positions of roll chocks of the upper roll assembly and positions of roll chocks of the lower roll assembly are simultaneously adjusted or are each independently adjusted; in a roll assembly on a side on which the vertical roll load measurement apparatus is installed, positions of the roll chocks of the rolls other than the reference roll are adjusted so that the vertical roll load difference is within a predetermined allowable range or so that a value of the torque is minimal; and in a roll assembly on a side on which the vertical roll load measurement apparatus is not installed, positions of the roll chocks of the rolls other than the reference roll are adjusted so that a value of the torque is minimal.
Further, in the rolling mill of four-high, when the pair of work rolls are simultaneously driven by one motor, a configuration may be adopted in which: in the first process, positions of roll chocks of the upper roll assembly and positions of roll chocks of the lower roll assembly are each independently adjusted; in a roll assembly on a side on which the vertical roll load measurement apparatus is installed, positions of the roll chocks of the rolls other than the reference roll are adjusted so that the vertical roll load difference is within a predetermined allowable range or so that a value of the torque is minimal; and in a roll assembly on a side on which the vertical roll load measurement apparatus is not installed, positions of the roll chocks of the rolls other than the reference roll are adjusted so that a value of the torque is minimal.
In addition, when the rolling mill is a six-high rolling mill that includes an intermediate roll between the work roll and the backup roll in the upper roll assembly and the lower roll assembly, respectively, and the work rolls are independently driven by different motors, respectively, a configuration may be adopted in which: in the first process, with respect to each of the upper roll assembly and the lower roll assembly, there are performed a first adjustment that adjusts positions of the roll chocks of the intermediate roll and the roll chocks of the backup roll, and a second adjustment that, after the first adjustment is performed, adjusts positions of the roll chocks of the intermediate roll and the roll chocks of the work roll; wherein, in the first adjustment: with respect to a roll assembly on a side on which the vertical roll load measurement apparatus is installed, positions of roll chocks of the work roll and roll chocks of the intermediate roll are adjusted simultaneously and in a same direction while maintaining relative positions between the roll chocks so that a value of the torque becomes minimal or so that the vertical roll load difference is within a predetermined allowable range, or a position of roll chocks of the backup roll that is not the reference roll is adjusted, and with respect to a roll assembly on a side on which the vertical roll load measurement apparatus is not installed, positions of roll chocks of the work roll and roll chocks of the intermediate roll are adjusted simultaneously and in a same direction while maintaining relative positions between the roll chocks so that a value of the torque becomes minimal, or a position of roll chocks of the backup roll that is not the reference roll is adjusted; and in the second adjustment: with respect to a roll assembly on a side on which the vertical roll load measurement apparatus is installed, a position of roll chocks of the work roll is adjusted so that a value of the torque becomes minimal or so that the vertical roll load difference is within a predetermined allowable range, or positions of roll chocks of the backup roll that is not the reference roll and roll chocks of the intermediate roll are adjusted simultaneously and in a same direction while maintaining relative positions between the roll chocks, and with respect to a roll assembly on a side on which the vertical roll load measurement apparatus is not installed, a position of roll chocks of the work roll is adjusted so that a value of the torque becomes minimal, or positions of roll chocks of the backup roll that is not the reference roll and roll chocks of the intermediate roll are adjusted simultaneously and in a same direction while maintaining relative positions between the roll chocks.
Further, when the rolling mill is a six-high rolling mill that includes an intermediate roll between the work roll and the backup roll in the upper roll assembly and the lower roll assembly, respectively, and the pair of work rolls are simultaneously driven by one motor, a configuration may be adopted in which: in the first process, separately for each of the upper roll assembly and the lower roll assembly, there are performed a first adjustment that adjusts positions of the roll chocks of the intermediate roll and the roll chocks of the backup roll, and a second adjustment that, after the first adjustment is performed, adjusts positions of the roll chocks of the intermediate roll and the roll chocks of the work roll; wherein, in the first adjustment: with respect to a roll assembly on a side on which the vertical roll load measurement apparatus is installed, positions of roll chocks of the work roll and roll chocks of the intermediate roll are adjusted simultaneously and in a same direction while maintaining relative positions between the roll chocks so that a value of the torque becomes minimal or so that the vertical roll load difference is within a predetermined allowable range, or a position of roll chocks of the backup roll that is not the reference roll is adjusted, and with respect to a roll assembly on a side on which the vertical roll load measurement apparatus is not installed, positions of roll chocks of the work roll and roll chocks of the intermediate roll are adjusted simultaneously and in a same direction while maintaining relative positions between the roll chocks so that a value of the torque becomes minimal, or a position of roll chocks of the backup roll that is not the reference roll is adjusted; and in the second adjustment: with respect to a roll assembly on a side on which the vertical roll load measurement apparatus is installed, a position of roll chocks of the work roll is adjusted so that a value of the torque becomes minimal or so that the vertical roll load difference is within a predetermined allowable range, or positions of roll chocks of the backup roll that is not the reference roll and roll chocks of the intermediate roll are adjusted simultaneously and in a same direction while maintaining relative positions between the roll chocks, and with respect to a roll assembly on a side on which the vertical roll load measurement apparatus is not installed, a position of roll chocks of the work roll is adjusted so that a value of the torque becomes minimal, or positions of roll chocks of the backup roll that is not the reference roll and roll chocks of the intermediate roll are adjusted simultaneously and in a same direction while maintaining relative positions between the roll chocks.
Further, to solve the problems described above, according to a different aspect of the present invention there is provided a rolling mill of four-high or more that includes a plurality of rolls including at least a pair of work rolls and a pair of backup rolls supporting the work rolls, with any one roll among the respective rolls that are arranged in a vertical direction being adopted as a reference roll, the rolling mill including: a torque measurement apparatus which measures a torque acting on the work rolls that is generated by driving of a motor that drives the work rolls; a vertical roll load measurement apparatus which is provided on a work side and a drive side on at least a lower side or an upper side of the rolling mill and which measures a vertical roll load in the vertical direction; a pressing apparatus which, with respect to at least roll chocks of the rolls other than the reference roll, is provided on either one of an entrance side and an exit side in a rolling direction, and which presses the roll chocks in a rolling direction of a workpiece; a roll chock driving apparatus which, with respect to at least roll chocks of the rolls other than the reference roll, is provided so as to face the pressing apparatus in the rolling direction, and which moves the roll chocks in a rolling direction of a workpiece; and a roll chock position control unit that fixes a rolling direction position of roll chocks of the reference roll as a reference position, and controls the roll chock driving apparatus based on the torque and a vertical roll load difference that is a difference between the vertical roll load on the work side and the vertical roll load on the drive side to adjust positions in a rolling direction of the roll chocks of the rolls other than the reference roll.
The upper work roll and the lower work roll may be independently driven vertically by different motors, respectively.
Alternatively, the upper work roll and the lower work roll may be simultaneously driven vertically by one motor.
As described above, according to the present invention, thrust forces generated between rolls can be reduced and the occurrence of zigzagging and camber of a workpiece can be suppressed.
Hereunder, preferred embodiments of the present invention are described in detail while referring to the accompanying drawings. Note that, in the present specification and the accompanying drawings, constituent elements having substantially the same functional configuration are denoted by the same reference characters and a duplicate description thereof is omitted.
An objective of a rolling mill as well as a method for setting the rolling mill according to the embodiments of the present invention is to eliminate thrust forces generated between rolls, and enable the stable production of products without zigzagging and camber or with extremely little zigzagging and camber. In
The rolling mill illustrated in
The upper work roll 1, the lower work roll 2, the upper backup roll 3 and the lower backup roll 4 are arranged in a manner in which the axial directions of the respective rolls are parallel, so as to be orthogonal with the conveyance direction of the workpiece S. In this case, if a roll rotates slightly about an axis (Z-axis) that is parallel with the vertical direction and a deviation arises between the axial directions of the upper work roll 1 and the upper backup roll 3, or a deviation arises between the axial directions of the lower work roll 2 and the lower backup roll 4, a thrust force that acts in the axial direction of the rolls arises between the work roll and the backup roll. An inter-roll thrust force gives an extra moment to the rolls, and causes asymmetric roll deformation to occur due to the aforementioned moment. The asymmetric roll deformation is a factor that causes the rolling to enter an unstable state, and for example gives rise to zigzagging or camber. The inter-roll thrust force is generated as a result of an inter-roll cross angle arising due to the occurrence of a deviation between the axial directions of a work roll and a backup roll. For example, let us assume that an inter-roll cross angle arises between the lower work roll 2 and the lower backup roll 4. At such time, a thrust force is generated between the lower work roll 2 and the lower backup roll 4, and as a result, a moment occurs at the lower backup roll 4, and the load distribution between the rolls changes to balance with the moment, and thus an asymmetric roll deformation occurs. Zigzagging or camber or the like is caused by the asymmetric roll deformation, and the rolling becomes unstable.
According to the present invention, to eliminate an inter-roll thrust force that arises between rolls during rolling of a workpiece by a rolling mill, a method for setting a rolling mill that is described hereunder is executed before reduction position zero point adjustment or before the start of rolling to thereby adjust the roll chock positions of each roll. An objective of the present invention is, by this means, to enable stable production of products without zigzagging and camber or with extremely little zigzagging and camber.
As illustrated in
Note that, in a case where it is possible to measure a vertical roll load in the vertical direction by means of a vertical roll load measurement apparatus on the work side and the drive side of a rolling mill, roll chock positions such that an inter-roll cross angle does not arise can also be identified based on a vertical roll load difference that is a difference between a vertical roll load on the work side and a vertical roll load on the drive side. In the first process, in each of the upper roll assembly and the lower roll assembly, adjustment is performed that eliminates an inter-roll cross angle that arises between a plurality of rolls constituting the relevant roll assembly.
After the first process is performed, as a second process, the work rolls are set in a kiss roll state and an adjustment is performed that eliminates an inter-roll cross angle in the upper roll assembly and lower roll assembly overall (S20). In the second process, the rolling direction position of the roll chocks of the reference roll are fixed as a reference position, and the roll chock positions of the respective rolls of the roll assembly on the opposite side to the reference roll are adjusted so that a vertical roll load difference between the pair of work rolls in two different rotational states is within a predetermined allowable range. At such time, the roll chocks of the roll assembly to be adjusted are moved simultaneously and in the same direction by a roll chock driving apparatus while maintaining the relative positions between the relevant roll chocks. By this means, the roll chock positions as a whole can be adjusted without disturbing the positional relationship between the roll chocks that were adjusted in the first process.
Hereunder, the configurations of rolling mills according to each embodiment of the present invention as well as a method for setting the respective rolling mills are described in detail.
The configuration of a rolling mill and an apparatus for controlling the rolling mill, as well as a method for setting the rolling mill according to a first embodiment of the present invention will be described based on
[2-1. Configuration of Rolling Mill]
First, the rolling mill according to the present embodiment and an apparatus for controlling the rolling mill will be described based on
The rolling mill illustrated in
The upper work roll 1 is rotationally driven by an upper driving electric motor 21a, and the lower work roll 2 is rotationally driven by a lower driving electric motor 21b. That is, the upper work roll 1 and the lower work roll 2 are configured to be independently rotatable. The upper driving electric motor 21a and the lower driving electric motor 21b are, for example, motors in which spindle torque measurement apparatuses 31a and 31b that measure the spindle torque of each motor are provided on the respective spindles thereof. The spindle torque measurement apparatuses 31a and 31b are, for example, load cells. An upper spindle torque measurement apparatus 31a that is provided on the upper driving electric motor 21a measures the spindle torque of the upper driving electric motor 21a, and outputs the measurement value to an inter-roll cross control unit 23 that is described later. Similarly, a lower spindle torque measurement apparatus 31b that is provided on the lower driving electric motor 21b measures the spindle torque of the lower driving electric motor 21b, and outputs the measurement value to the inter-roll cross control unit 23 that is described later.
The upper backup roll 3 is supported by the upper backup roll chocks 7a and 7b, and the lower backup roll 4 is supported by the lower backup roll chocks 8a and 8b. As illustrated in
The upper work roll chocks 5a and 5b are provided with an upper work roll chock pressing apparatus 9 which is provided on the entrance side in the rolling direction and which presses the upper work roll chocks 5a and 5b in the rolling direction, and an upper work roll chock driving apparatus 11 which is provided on the exit side in the rolling direction and which detects the position in the rolling direction and drives the upper work roll chocks 5a and 5b in the rolling direction. The upper work roll chock driving apparatus 11 is equipped with a position detecting apparatus that detects the position of the upper work roll chocks. Similarly, the lower work roll chocks 6a and 6b are provided with a lower work roll chock pressing apparatus 10 which is provided on the entrance side in the rolling direction and which presses the lower work roll chocks 6a and 6b in the rolling direction, and a lower work roll chock driving apparatus 12 which is provided on the exit side in the rolling direction and which detects the position in the rolling direction and drives the lower work roll chocks 6a and 6b. The lower work roll chock driving apparatus 12 is equipped with a position detecting apparatus that detects the position of the lower work roll chocks.
For example, a hydraulic cylinder is used as the upper work roll chock driving apparatus 11, the lower work roll chock driving apparatus 12, a drive mechanism of the upper work roll chock pressing apparatus 9 and a drive mechanism of the lower work roll chock pressing apparatus 10. Note that although the upper and lower work roll chock driving apparatuses 11 and 12 and the upper and lower work roll chock pressing apparatuses 9 and 10 are shown only on the work side in
The upper backup roll chocks 7a and 7b are provided with an upper backup roll chock pressing apparatus 13 which is provided on the exit side in the rolling direction and which presses the upper backup roll chocks 7a and 7b in the rolling direction, and an upper backup roll chock driving apparatus 14 which is provided on the entrance side in the rolling direction and which detects the position in the rolling direction and drives the upper backup roll chocks 7a and 7b in the rolling direction. The upper backup roll chock driving apparatus 14 is equipped with a position detecting apparatus that detects the position of the upper backup roll chocks. For example, a hydraulic cylinder is used as the upper backup roll chock driving apparatus 14 and the drive mechanism of the upper backup roll chock pressing apparatus 13. Note that although the upper backup roll chock driving apparatus 14 and the upper backup roll chock pressing apparatus 13 are shown only on the work side in
On the other hand, with respect to the lower backup roll chocks 8a and 8b, since the lower backup roll 4 is adopted as the reference roll in the present embodiment, the lower backup roll chocks 8a and 8b serve as reference backup roll chocks. Accordingly, since the lower backup roll chocks 8a and 8b are not driven to perform position adjustment, the lower backup roll chocks 8a and 8b do not necessarily need to be equipped with a driving apparatus and a position detecting apparatus as in the case of the upper backup roll chocks 7a and 7b. However, a configuration may be adopted in which, for example, a lower backup roll chock pressing apparatus 40 or the like is provided on the entrance side or the exit side in the rolling direction to suppress the occurrence of looseness of the lower backup roll chocks 8a and 8b so that the position of the reference backup roll chocks that serve as the reference for position adjustment does not change. Note that although the lower backup roll chock pressing apparatus 40 is shown only on the work side in
A pressing-down device 50 is provided between the housing 30 and the upper backup roll chocks 7a and 7b, and adjusts the roll positions in the vertical direction. An upper vertical roll load measurement apparatus 71 that measures a vertical roll load applied to the upper backup roll chocks 7a and 7b is provided between the pressing-down device 50 and the upper backup roll chocks 7a and 7b. Note that although the pressing-down device 50 and the upper vertical roll load measurement apparatus 71 are shown only on the work side in
The rolling mill according to the present embodiment includes an entrance-side upper increase bending apparatus 61a and an exit-side upper increase bending apparatus 61b on a project block between the upper work roll chocks 5a and 5b and the housing 30, and includes an entrance-side lower increase bending apparatus 62a and an exit-side lower increase bending apparatus 62b on a project block between the lower work roll chocks 6a and 6b and the housing 30. Further, although not illustrated in the drawing, on the side facing away from the viewer (drive side) in
As apparatuses for controlling the rolling mill, for example, as illustrated in
The roll chock rolling direction force control unit 15 controls a pressing force in the rolling direction of the upper work roll chock pressing apparatus 9, the lower work roll chock pressing apparatus 10, the upper backup roll chock pressing apparatus 13 and the lower backup roll chock pressing apparatus 40. Based on a control instruction of the inter-roll cross control unit 23 that is described later, the roll chock rolling direction force control unit 15 drives the upper work roll chock pressing apparatus 9, the lower work roll chock pressing apparatus 10, and the upper backup roll chock pressing apparatus 13, to produce a state in which it is possible to control the roll chock positions by applying a predetermined pressing force which corresponds to the roll chocks that are the control objects.
The roll chock position control unit 16 performs drive control of the upper work roll chock driving apparatus 11, the lower work roll chock driving apparatus 12, and the upper backup roll chock driving apparatus 14. Based on a control instruction of the inter-roll cross control unit 23, the roll chock position control unit 16 drives the upper work roll chock driving apparatus 11, the lower work roll chock driving apparatus 12 and the upper backup roll chock driving apparatus 14 so that a vertical roll load difference is within a predetermined range or so that the torque becomes minimal. The respective roll chock driving apparatuses 11, 12 and 14 are disposed on both the work side and the drive side, and with respect to the positions in the rolling direction on the work side and the drive side, by controlling the roll chock driving apparatuses 11, 12 and 14 so that the positions change by the same amount in opposite directions on the work side and the drive side, only a roll cross angle can be changed, without changing the average rolling direction position of the work side and drive side.
The driving electric motor control unit 22 controls the upper driving electric motor 21a that rotationally drives the upper work roll 1, and the lower driving electric motor 21b that rotationally drives the lower work roll 2. Based on an instruction from the inter-roll cross control unit 23, the driving electric motor control unit 22 according to the present embodiment drives the upper driving electric motor 21a and the lower driving electric motor 21b to control driving of the upper work roll 1 or the lower work roll 2.
The inter-roll cross control unit 23 controls the position of each of the upper work roll 1, the lower work roll 2, the upper backup roll 3 and the lower backup roll 4 constituting the rolling mill by adjusting the positions of the roll chocks, so that an inter-roll cross angle is zero. In the rolling mill according to the present embodiment, the positions of the roll chocks are adjusted based on the spindle torque of the upper driving electric motor 21a measured by the upper spindle torque measurement apparatus 31a, the spindle torque of the lower driving electric motor 21b measured by the lower spindle torque measurement apparatus 31b, and a difference between the vertical roll load on the work side and the vertical roll load of the drive side (hereunder, also referred to as “vertical roll load difference”) measured by the upper vertical roll load measurement apparatus 71. Based on these measurement values, the inter-roll cross control unit 23 issues control instructions to the roll chock rolling direction force control unit 15, the roll chock position control unit 16 and the driving electric motor control unit 22 so that crossing that has occurred between rolls is eliminated. Note that the details of the method for setting the rolling mill are described later.
The roll bending control unit 63 is an apparatus that controls each of the increase bending apparatuses 61a to 61d, and 62a to 62d. The roll bending control unit 63 according to the present embodiment controls the increase bending apparatuses so as to impart an increase bending force to the work roll chocks, based on an instruction from the inter-roll cross control unit 23. Note that, the roll bending control unit 63 may also be used in a case other than a case of performing adjustment of inter-roll cross according to the present embodiment, for example, when performing crown control or shape control of a workpiece.
The configuration of the rolling mill according to the present embodiment has been described above. Note that, although in
Furthermore, although an example has been described above in which a roll chock driving apparatus is provided on the work side and the drive side for all of the rolls except the reference roll, the present invention is not limited to this example. For example, all of the rolls may be provided with a roll chock driving apparatus, and the reference roll may be changed according to the situation, and control performed based on the changed reference roll. Alternatively, the roll chock driving apparatus may be provided on either one side among the work side and the drive side, with the opposite side being taken as a pivot, and the inter-roll cross angle may be similarly controlled by controlling only the roll chock positions on one side.
[2-2. Method for Setting Rolling Mill]
The method for setting a rolling mill according to the present embodiment will now be described based on
Although in the present example the lower backup roll 4 is described as the reference roll, there are also cases where the upper backup roll 3 serves as the reference roll. Note that, it suffices to set any one roll constituting the rolling mill as the reference roll, and it is preferable to adopt either the roll at the uppermost part or the roll at the lowermost part in the vertical direction as the reference roll. For example, in a case where the upper backup roll 3 is adopted as the reference roll, by similar procedures as described hereunder, it suffices to perform position adjustment of rolls in order from the roll assembly on the opposite side to the reference roll in a manner such that, first, position adjustment is performed between the roll (lower backup roll 4) that is furthest from the reference roll (upper backup roll 3) and the roll (lower work roll 2) that is second furthest from the reference roll, followed by position adjustment between the aforementioned two rolls and the roll (upper work roll 1) that is third furthest from the reference roll, and finally position adjustment between the aforementioned three rolls and the reference roll. Note that, in the present invention, the term “roll assembly” means a roll group that includes a plurality of rolls.
(First Adjustment: S100 to S110)
A first adjustment according to the present embodiment corresponds to the first process shown in
Further, the inter-roll cross control unit 23 instructs the roll bending control unit 63 so as to apply a predetermined increase bending force from the balanced state to the work roll chocks 5a, 5b and 6 by means of the increase bending apparatuses 61a to 61d and 62a to 62d (S102). The roll bending control unit 63 controls the respective increase bending apparatuses 61a to 61d and 62a to 62d based on the instruction, to thereby apply a predetermined increase bending force to the work roll chocks 5a, 5b and 6. By this means, the roll gap between the work rolls is placed in an open state. Note that, either step among the step S100 and step S102 may be executed first.
Next, the inter-roll cross control unit 23 causes the driving electric motor control unit 22 to drive the upper driving electric motor 21a and the lower driving electric motor 21b. By the driving of the upper driving electric motor 21a and the lower driving electric motor 21b, the work rolls 1 and 2 rotate at a predetermined rotational speed (S104).
Next, position adjustment of the respective rolls is performed in a stepwise manner. At such time, the rolling direction position of the roll chocks of the reference roll is fixed as a reference position, and the positions in the rolling direction of the roll chocks of the rolls other than the reference roll are moved to thereby adjust the positions of the roll chocks.
Specifically, with respect to each of the upper roll assembly that is composed of the upper work roll 1 and the upper backup roll 3, and the lower roll assembly that is composed of the lower work roll 2 and the lower backup roll 4, the positions of roll chocks are adjusted so that the spindle torques measured by the spindle torque measurement apparatuses 31a and 31b become minimal values. This is based on the finding that, when the work rolls are in an open state, a cross angle between the work roll and the backup roll is zero and the spindle torque is a minimal value. Therefore, in the first adjustment, measurement of the spindle torques by the spindle torque measurement apparatuses 31a and 31b (S106) and driving of roll chock positions (S108) are repeatedly performed, and roll chock positions at which the spindle torque is minimal are identified for each of the upper roll assembly and the lower roll assembly (S110).
The roll chocks of rolls other than the reference roll are the object of the driving of roll chock positions in step S108. That is, with regard to the upper roll assembly, as illustrated on the upper side in
(Second Adjustment: S112 to S126)
Next, as illustrated in
Next, the inter-roll cross control unit 23 drives the driving electric motors 21a and 21b by means of the driving electric motor control unit 22, to thereby cause the upper work roll 1 and the lower work roll 2 to rotate in a predetermined rotational direction at a predetermined rotational speed (S114; P15 in
Note that, the reference value of the vertical roll load difference that is set in step S116 need not be a value for a time that the work rolls rotate in the normal direction, and for example as illustrated on the upper right side in
Upon the reference value of the vertical roll load difference being set in step S116, the inter-roll cross control unit 23 controls driving of the driving electric motors 21a and 21b by the driving electric motor control unit 22 to cause the upper work roll 1 and the lower work roll 2 to rotate in the opposite rotational direction to the rotational direction in step S114 at a predetermined rotational speed (S118; P16 in
Upon the vertical roll loads on the work side and the drive side during reverse rotation that were measured by the upper vertical roll load measurement apparatus 71 being input to the inter-roll cross control unit 23, the inter-roll cross control unit 23 calculates a vertical roll load difference by calculating the difference between the vertical roll load on the work side and the vertical roll load on the drive side. The inter-roll cross control unit 23 then calculates a control target value based on a deviation between the calculated vertical roll load difference and the reference value that was calculated in step S116 (S119). The control target value may also be, for example, a value that is one-half of the deviation from the reference value, by utilizing the characteristic that absolute values of vertical roll load differences caused by inter-roll thrust forces during normal rotation and during reverse rotation are approximately the same.
Further, upon the vertical roll load difference during reverse rotation of the work rolls being calculated by the inter-roll cross control unit 23 (S120), the inter-roll cross control unit 23 controls the positions of the roll chocks of the work roll and the backup roll on the opposite side to the reference roll so that the vertical roll load difference becomes the control target value that was set in step S116 (S122). In the example illustrated in
The processing in steps S120 to S124 is repeatedly executed until it is determined in step S124 that the vertical roll load difference has become the control target value. Note that, the vertical roll load difference need not perfectly match the control target value, and the inter-roll cross control unit 23 may be configured to determine that the vertical roll load difference has become the control target value as long as the difference between these values is within an allowable range. When it is determined that the vertical roll load difference has become the control target value, the inter-roll cross control unit 23 causes the pressing-down device 50 to adjust the roll positions so that the roll gap between the upper work roll 1 and the lower work roll 2 becomes a predetermined size (S126). Thereafter, rolling of a workpiece by the rolling mill is started.
A rolling apparatus and a method for setting a rolling mill according to the first embodiment of the present invention are described above. According to the present embodiment, utilizing the characteristic that the spindle torque changes accompanying a change in a cross angle, in the first adjustment the cross angles between the work rolls and backup rolls of the upper roll assembly and the lower roll assembly are adjusted based on the spindle torque of the upper work roll and the lower work roll. In the second adjustment, the work rolls are set in a kiss roll state, and the cross angle between the upper work roll and the lower work roll is adjusted based on a vertical roll load difference. In the kiss roll state, because a tangential force that depends on the roll profiles exerts an influence between the upper work roll and the lower work roll, the vertical roll load difference is used, and not the spindle torque. By setting the rolling mill in this way, a thrust force generated between rolls due to the inter-roll cross angle can be reduced, and the occurrence of zigzagging and camber of a workpiece during rolling can be suppressed.
Note that, although it is described in the above that, in the first adjustment, roll chock positions are adjusted based on the spindle torque of the upper work roll and the lower work roll, the present invention is not limited to this example, and for example the rolling mill can also be similarly set using the motor torque of the driving electric motors 21a and 21b. The motor torque is proportional to the electric current values of the driving electric motors 21a and 21b, and therefore the roll chock positions can be adjusted based on the electric current values of the driving electric motors 21a and 21b as values of the motor torque.
Further, in the foregoing example, although in the first adjustment the roll chock positions of the upper work roll and the lower work roll are adjusted based on the torque, it suffices to adjust roll chock positions based on the torque with respect to at least the roll assembly on the side on which the vertical roll load measurement apparatus is not installed. With regard to the roll assembly on the side on which the vertical roll load measurement apparatus is installed, the positions of the roll chocks may be adjusted so that the vertical roll load difference is within a predetermined allowable range. In this case, the predetermined allowable range may be, for example, a range that is less than or equal to a control target value of a vertical roll load difference that is calculated based on a reference value determined in a rotational state of the rolls that is opposite to a state when adjusting the positions of the roll chocks or in a state in which the rolls are stopped. Note that, the predetermined allowable range need not perfectly match a range determined in this manner, and there may be a certain amount of difference therebetween.
Next, the configuration of a rolling mill and an apparatus for controlling the rolling mill, as well as a method for setting the rolling mill according to a second embodiment of the present invention will be described based on
[3-1. Configuration of Rolling Mill]
First, the rolling mill according to the present embodiment and an apparatus for controlling the rolling mill will be described based on
The rolling mill according to the present embodiment illustrated in
The driving electric motor 21 is a driving apparatus that simultaneously rotates the upper work roll 1 and the lower work roll 2. The driving electric motor 21 is, for example, a motor. In the present embodiment, the motor torque of the driving electric motor 21 is used as a detection terminal. Specifically, the electric current value of the driving electric motor 21 that is in a proportional relationship with the motor torque may be output as the motor torque to the inter-roll cross control unit 23.
The lower vertical roll load measurement apparatus 73 is provided on the lower side of the rolling mill (that is, between the housing 30 and the lower backup roll chocks 8a and 8b), and measures a vertical roll load applied to the lower backup roll chocks 8a and 8b. A vertical roll load that is measured by the lower vertical roll load measurement apparatus 73 is output to the inter-roll cross control unit 23. Note that, although the lower vertical roll load measurement apparatus 73 is only shown on the work side in
[3-2. Method for Setting Rolling Mill]
Next, a method for setting a rolling mill according to the present embodiment will be described based on
In the present embodiment, a first adjustment of steps S200 to S214 and a second adjustment of steps S216 to S220 are performed as a first process that is performed when the roll gap illustrated in
(First Adjustment: S200 to S214)
First, in the first adjustment, adjustment of roll chock positions of the lower roll assembly in which the lower vertical roll load measurement apparatus 73 is provided is performed. As illustrated in
Further, the inter-roll cross control unit 23 instructs the roll bending control unit 63 so as to apply a predetermined increase bending force from the balanced state to the work roll chocks 5a, 5b and 6 by means of the increase bending apparatuses 61a to 61d and 62a to 62d (S202). The roll bending control unit 63 controls the respective increase bending apparatuses 61a to 61d and 62a to 62d based on the instruction, to thereby apply a predetermined increase bending force to the work roll chocks 5a, 5b and 6. By this means, the roll gap between the work rolls is placed in an open state. Note that, either step among the step S200 and step S202 may be executed first.
Next, in a state in which the upper work roll 1 and the lower work roll 2 are stopped, the vertical roll load on the work side and the vertical roll load on the drive side are measured by the lower vertical roll load measurement apparatus 73 (S204). The inter-roll cross control unit 23 then calculates the difference between the vertical roll load on the work side and the vertical roll load on the drive side that were measured in step S204, and sets the calculated difference as a first control target value (S206; P21 in
Upon the vertical roll load difference during rotation of the lower work roll being calculated in step S210, the inter-roll cross control unit 23 controls the position of the roll chocks of the lower work roll 2 so that the vertical roll load difference becomes the first control target value that was set in step S206 (S212; P22 in
The first control target value that is set in step S206 need not be a value obtained at a time when the work rolls are in a stopped state, and as illustrated on the upper right side in
(Second Adjustment: S216 to S220)
Next, in the second adjustment, adjustment of roll chock positions of the upper roll assembly in which a vertical roll load measurement apparatus is not provided is performed. As illustrated in
Since it suffices that the driving of roll chock positions in step S218 is performed with respect to the roll chocks of rolls other than the reference roll, with regard to the upper roll assembly, as illustrated on the upper side in
(Third Adjustment: S222 to S236)
Next, as illustrated in
Next, in a state in which the upper work roll 1 and the lower work roll 2 are stopped, the inter-roll cross control unit 23 measures the vertical roll load on the work side and the vertical roll load on the drive side by means of the lower vertical roll load measurement apparatus 73 (S224). The inter-roll cross control unit 23 then calculates the difference between the vertical roll load on the work side and the vertical roll load on the drive side that were measured in step S224, and sets the calculated difference as a second control target value (S226; P25 in
Upon the vertical roll load difference during rotation of the work rolls being calculated in step S230, the inter-roll cross control unit 23 controls the positions of the roll chocks of the work roll and the backup roll on the opposite side to the reference roll so that the vertical roll load difference becomes the second control target value that was set in step S226 (S232; P26 in
The processing in steps S230 to S234 is repeatedly executed until it is determined in step S234 that the vertical roll load difference has become the second control target value. Note that, the vertical roll load difference need not perfectly match the second control target value, and the inter-roll cross control unit 23 may be configured to determine that the vertical roll load difference has become the second control target value as long as a difference between these values is within an allowable range. When it is determined that the vertical roll load difference has become the second control target value, the inter-roll cross control unit 23 causes the pressing-down device 50 to adjust the roll positions so that the roll gap between the upper work roll 1 and the lower work roll 2 becomes a predetermined size (S236). Thereafter, rolling of a workpiece by the rolling mill is started.
The second control target value that is set in step S226 need not be a value obtained at a time when the work rolls are in a stopped state, and as illustrated on the upper right side in
A rolling apparatus and a method for setting the rolling mill according to the second embodiment of the present invention have been described above. According to the present embodiment, in a case where the rolling mill is a single drive mill, with respect to the roll assembly on the side on which the vertical roll load measurement apparatus is provided, the inter-roll cross angle is adjusted based on a vertical roll load difference, while with respect to the roll assembly on the side on which the vertical roll load measurement apparatus is not provided, the inter-roll cross angle is adjusted based on the motor torque of the driving electric motor by utilizing the characteristic that the motor torque changes accompanying a change in the cross angle. Further, upon completing adjustment of the inter-roll cross angle with respect to the upper and lower roll assemblies, the work rolls are set in a kiss roll state, and the cross angle between the upper work roll and the lower work roll is adjusted based on the vertical roll load difference. By setting the rolling mill in this way, a thrust force generated between rolls due to the inter-roll cross angle can be reduced, and the occurrence of zigzagging and camber of a workpiece during rolling can be suppressed.
Note that, although it is described above that, in the second adjustment, roll chock positions are adjusted based on the motor torque of the driving electric motor, the present invention is not limited to this example, and similarly to the first embodiment, the rolling mill can also be similarly set using the spindle torque of the driving electric motor. At such time, a spindle torque measurement apparatus for measuring the spindle torque of the driving electric motor is provided in the rolling mill, and if two spindle torque measurement apparatuses that are to be used for the upper work roll and the lower work roll, respectively, are provided, it will be possible to adjust the roll chock positions based on the spindle torque in each of the upper and lower roll assemblies without using vertical roll load differences.
Furthermore, although it is described above that, in the first adjustment, with respect to the roll assembly on the side on which the vertical roll load measurement apparatus is installed, the positions of roll chocks are adjusted so that the vertical roll load difference falls within a predetermined allowable range, the present invention is not limited to this example, and similarly to the second adjustment, the roll chock positions may be adjusted based on the torque.
In the method for setting a rolling mill according to the first and second embodiment described above, in order to eliminate an inter-roll cross, control of the positions of roll chocks is performed so that a vertical roll load difference becomes zero or becomes a value within an allowable range, or so that the torque becomes minimal. This is based on the finding that correlations which are described below exist between the inter-roll cross angle and the vertical roll load difference, the motor torque, and the spindle torque. The relations between the inter-roll cross angle and the various values are described hereunder based on
[4-1. Method for Calculating Behavior of Vertical Roll Load Difference Between Time of Normal Roll Rotation and Time of Reverse Roll Rotation, and Control Target Value]
In the foregoing first and second embodiments, to perform adjustment based on a vertical roll load difference, with respect to the vertical roll load difference that is a difference between a vertical roll load on the work side and a vertical roll load on the drive side, the relation between vertical roll load differences during normal rotation of rolls and during reverse rotation of rolls was studied. In the study, for example, as illustrated in
Note that, the work side of the upper work roll 1 is supported by the upper work roll chock 5a, and the drive side of the upper work roll 1 is supported by the upper work roll chock 5b. The work side of the lower work roll 2 is supported by the lower work roll chock 6a, and the drive side of the lower work roll 2 is supported by the lower work roll chock 6b. The work side of the upper backup roll 3 is supported by the upper backup roll chock 7a, and the drive side of the upper backup roll 3 is supported by the upper backup roll chock 7b. Further, the work side of the lower backup roll 4 is supported by the lower backup roll chock 8a, and the drive side of the lower backup roll 4 is supported by the lower backup roll chock 8b. In a state in which the work rolls 1 and 2 are separated from each other, an increase bending force is applied by increase bending apparatuses (not illustrated) to the upper work roll chocks 5a and 5b and the lower work roll chocks 6a and 6b.
As illustrated in
According to the detection results, a vertical roll load difference acquired during normal roll rotation increases in the negative direction in comparison to the value thereof before changing the inter-roll cross angle. On the other hand, a vertical roll load difference acquired during reverse roll rotation increases in the positive direction in comparison to the value thereof before changing the inter-roll cross angle. Thus, although the sizes of vertical roll load differences during normal roll rotation and during reverse roll rotation are approximately the same, the directions thereof are opposite to each other.
Therefore, based on the aforementioned relation, the state during normal roll rotation is taken as a reference, and one-half of a deviation from the reference in the state of reverse roll rotation is taken as a control target value for a vertical roll load difference at which a thrust force between the work roll and the backup roll on the upper side and the lower side, respectively, becomes zero. The control target values can be expressed by the following formula (1).
Here, P′dfTT represents a control target value of the upper roll assembly, and P′dfTB represents a control target value of the lower roll assembly. Further, PdfT and P′dfT represent differences between the work side and the drive side in vertical roll load measurement values for the upper roll assembly during normal roll rotation and a state of reverse roll rotation, and PdfB and P′dfB represent vertical roll load differences between the work side and the drive side in the vertical roll load measurement values for the lower roll assembly in the state of normal roll rotation and the state of reverse roll rotation. In this way, control target values for the upper roll assembly and the lower roll assembly can be calculated.
Therefore, based on the aforementioned relation, for example, the inter-roll thrust force can be made zero by calculating a control target value by taking a normal roll rotation state as a reference (that is, a reference value for the vertical roll load difference), and making a vertical roll load difference in a reverse roll rotation state match the control target value.
[4-2. Method for Calculating Behavior of Vertical Roll Load Difference Between Time when Rolls are Stopped and Time of Rotation, and Control Target Value]
As illustrated in
Thus, it is considered that a vertical roll load difference that arises in a state in which rolls are stopped is caused by a factor other than a thrust force. Therefore, thrust forces between upper and lower work rolls and backup rolls can be made zero by setting control target values that take a vertical roll load difference in a state in which the rolls are stopped as a reference and controlling the roll chock positions. That is, the control target values are expressed by the following formula (2).
Here, PrdfTT represents a control target value of the upper roll assembly, and PrdfTB represents a control target value of the lower roll assembly. Further, P0dfT represents a vertical roll load difference between the work side and the drive side in vertical roll load measurement values of the upper roll assembly in a state in which roll rotation is stopped, and P0dfB represents a vertical roll load difference between the work side and the drive side in vertical roll load measurement values of the lower roll assembly in a state in which roll rotation is stopped. Note that, in this case, the direction in a state of roll rotation is not particularly defined, and rotation of rolls may be either normal rotation or reverse rotation. In this way, control target values for the upper roll assembly and the lower roll assembly can be calculated.
Therefore, based on the aforementioned relation, a thrust force between rolls can be made zero by setting a vertical roll load difference when rolls are in a stopped state as a control target value, and controlling roll chock positions during roll rotation (for example, during reverse roll rotation) so as to make a vertical roll load difference in the state of reverse roll rotation match the control target value.
Note that, the experimental results and the methods for calculating control target values described above are for cases where the roll gap was set in an open state and the influence that a thrust force acting between a work roll and a backup roll exerted on a vertical roll load difference appeared. In a kiss roll state also, as long as the state is one in which an inter-roll cross angle between a work roll and a backup roll was adjusted, the influence that a thrust force acting between upper and lower work rolls exerts on the vertical roll load difference is the same as in a case where the roll gap is set in an open state, and the methods for calculating control target values can also be similarly applied.
[4-3. Relations when Roll Gap is in Open State]
First, based on
As illustrated in
As a result it was found that, as illustrated in
This is because, as illustrated in
[4-4. Relations in Kiss Roll State (With a Pair Cross)]
Next, the relations between an inter-roll cross and various values in a case where the work rolls are in a kiss roll state will be described based on
In this case, as illustrated in
As a result it was found that, as illustrated in
A conventional method and the method of the present invention were compared in relation to reduction leveling setting that takes into consideration the influence of a thrust force due to an inter-roll cross in a so-called “twin-drive hot rolled thick-gauge plate rolling mill” in which the upper work roll 1 and the lower work roll 2 are configured to be independently rotatable that is illustrated in
First, in the conventional method, without using the functions of the inter-roll crossing control unit of the present invention, replacement of housing liners and chock liners was periodically performed, and equipment management was conducted so that an inter-roll cross would not occur.
On the other hand, in the method of the present invention, using the functions of the inter-roll cross control unit according to the first embodiment that is described above, adjustment of the positions of roll chocks was performed in accordance with the processing flow illustrated in
Table 1 shows actual measurement values for the occurrence of camber with regard to a representative number of rolled workpieces, with respect to the present invention and the conventional method. Among the actual measurement values for camber per 1 m of a front end portion of the workpieces, when the value for immediately before backup roll replacement and immediately before housing liner replacement are seen, it is found that in the case of the present invention the value is kept to a relatively small value of 0.13 mm/m. In contrast, in the case of the conventional method, in a period immediately before backup roll replacement and immediately before housing liner replacement, the actual measurement value for camber is large in comparison to the case of the present invention.
Thus, in the method of the present invention, before rolling, the positions of the upper and lower work roll chocks are controlled based on values for the upper and lower spindle torque that were measured when the roll gap was set in an open state, and thereafter control of the chock positions of each roll of the roll assembly on the opposite side to the reference roll is performed so that the vertical roll load difference when the work rolls are set in a kiss roll state becomes a control target value that is set in advance, and by this means the inter-roll cross itself is eliminated, and left-right asymmetric deformation of a workpiece that occurs due to thrust forces caused by an inter-roll cross can be eliminated. Therefore, a metal plate material can be stably produced without zigzagging and camber or with extremely little zigzagging and camber.
Next, for fifth to seventh stands of a hot finish rolling mill configured so that in each stand the upper work roll and the lower work roll are driven by a single driving electric motor through a pinion stand or the like as illustrated in
First, in the conventional method, without using the functions of the inter-roll cross control unit of the present invention, replacement of housing liners and chock liners was periodically performed, and equipment management was conducted so that an inter-roll cross would not occur. As a result, in a period immediately before replacement of the housing liner, when a thin and wide material having an exit side plate thickness of 1.2 mm and a width of 1200 mm was rolled, zigzagging of 100 mm or more occurred at the sixth stand, and swaging occurred as a result.
On the other hand, in the method of the present invention, using the functions of the inter-roll cross control unit according to the second embodiment that is described above, in accordance with the processing flow illustrated in
As a result, in a period immediately before replacement of the housing liner also, even in a case where a thin and wide material having an exit side plate thickness of 1.2 mm and a width of 1200 mm with respect to which swaging occurred in the conventional method was rolled, the occurrence of zigzagging stayed at 15 mm or less, and the workpiece could be passed through the rolling line without causing swaging of the workpiece.
As described above, in the method of the present invention, before rolling, the roll gap is set in an open state and the position of the roll chocks of the work roll on the side on which the vertical roll load measurement apparatus is provided is adjusted based on a vertical roll load difference, and furthermore, the roll chock positions of the roll assembly on the side on which the vertical roll load measurement apparatus is not provided are adjusted so that the motor torque becomes minimal, and thereafter by setting the work rolls in a kiss roll state and controlling the positions of the roll chocks of the roll assembly on the side on which the vertical roll load measurement apparatus is not provided based on the vertical roll load difference, the inter-roll cross itself is eliminated, and left-right asymmetric deformation of a workpiece that occurs due to thrust forces caused by an inter-roll cross can be eliminated. Therefore, a metal plate material can be stably produced without zigzagging and camber or with extremely little zigzagging and camber.
Whilst preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the above examples. It is clear that a person having common knowledge in the field of the art to which the present invention pertains will be able to contrive various examples of changes and modifications within the category of the technical idea described in the appended claims, and it should be understood that they also naturally belong to the technical scope of the present invention.
Whilst a four-high rolling mill having a pair of work rolls and a pair of backup rolls has been described in the above embodiments, the present invention is also applicable to a rolling mill of having more rolls than a four-high rolling mill. In such a case also, it suffices to set any one roll among the rolls constituting the rolling mill as the reference roll. For example, in the case of a six-high rolling mill, any roll among the work rolls, intermediate rolls and backup rolls can be set as the reference roll. At such time, similarly to the case of a four-high rolling mill, it is preferable that among the respective rolls arranged in the vertical direction, a roll located at the lowermost part or the uppermost part is adopted as the reference roll.
(1) Case of Vertical Independent Driving
For example, as illustrated in
The upper work roll 1 is rotationally driven by an upper driving electric motor 21a, and the lower work roll 2 is rotationally driven by a lower driving electric motor 21b. That is, in the example illustrated in
In the upper work roll chocks 5a and 5b, as in the four-high rolling mill illustrated in
Further, in the upper intermediate roll chocks 43a and 43b, an upper intermediate roll chock pressing apparatus (not illustrated) is provided on the work side and the drive side, respectively, on the exit side in the rolling direction, and an upper intermediate roll chock driving apparatus (not illustrated) is provided on the work side and the drive side, respectively, on the entrance side in the rolling direction. Similarly, in the lower intermediate roll chocks 44a and 44b, a lower intermediate roll chock pressing apparatus (not illustrated) is provided on the work side and the drive side, respectively, on the exit side in the rolling direction, and a lower intermediate roll chock driving apparatus (not illustrated) is provided on the work side and the drive side, respectively, on the entrance side in the rolling direction. The upper and lower intermediate roll chock driving apparatuses are each equipped with a position detecting apparatus that detect the positions of the intermediate roll chocks 43a, 43b, 44a and 44b.
In addition, as in the configuration of the four-high rolling mill illustrated in
On the other hand, with respect to the lower backup roll chocks 8a and 8b, since the lower backup roll 4 is adopted as the reference roll in the present embodiment, the lower backup roll chocks 8a and 8b serve as reference backup roll chocks. Accordingly, since the lower backup roll chocks 8a and 8b are not driven to perform position adjustment, the lower backup roll chocks 8a and 8b do not necessarily need to be equipped with a roll chock driving apparatus and a position detecting apparatus as in the case of the upper backup roll chocks 7a and 7b. However, a configuration may be adopted in which, for example, as illustrated in
In the six-high rolling mill also, setting of the rolling mill that is performed before reduction position zero point adjustment or before the start of rolling may be performed in a similar manner to the case of the four-high rolling mill illustrated in
For example, in the first adjustment, as illustrated on the upper side in
Alternatively, in the first adjustment, as illustrated on the lower side in
Further,
Note that, in the case illustrated in
Note that, in the first adjustment, a bending force is applied between the intermediate rolls 41 and 42 and the backup rolls 3 and 4 using bending apparatuses of the intermediate rolls 41 and 42. At such time, the bending apparatuses of the work rolls 1 and 2 apply a bending force of a degree such that the intermediate rolls 41 and 42 and the work rolls 1 and 2 do not slip.
Next, in the second adjustment, for example, as illustrated on the upper side in
Alternatively, as illustrated on the lower side in
Further, in the second adjustment, in the roll assembly on the side on which the vertical roll load measurement apparatuses are installed, the position of the roll chocks of the work roll may be adjusted so that the vertical roll load difference falls within a predetermined allowable range. For example, in
On the other hand, with regard to the roll assembly on the side on which the vertical roll load measurement apparatuses are not installed, that is, the lower roll assembly in
In the second adjustment, bending apparatuses of the work rolls 1 and 2 are used to apply loads between the work rolls 1 and 2 and the intermediate rolls 41 and 42. At such time, the bending apparatuses of the intermediate rolls 41 and 42 are set to zero or in a balanced state. Note that, in a case where the intermediate rolls 41 and 42 have a decrease bending apparatus, the decrease bending apparatuses may be caused to act in a direction (negative direction) such that the loads between the intermediate rolls 41 and 42 and the backup rolls 3 and 4 are removed.
Next, when the first process is completed, as illustrated in
The second process corresponds to the second process shown in
(2) Case of Vertical Simultaneous Driving
Further, in a six-high rolling mill, for example, as illustrated in
In the six-high rolling mill illustrated in
Note that, the order of performing the first adjustment and the second adjustment in the upper roll assembly and lower roll assembly is not particularly limited. For example, the first adjustment and the second adjustment may be performed in that order for the upper roll assembly and the lower roll assembly, respectively, or the first adjustment of the upper roll assembly and the lower roll assembly may be performed, and thereafter the second adjustment of the upper roll assembly and the lower roll assembly may be performed.
For example, in the first adjustment, as illustrated on the upper side in
Alternatively, with regard to the upper roll assembly, as illustrated on the lower side in
On the other hand, with regard to the lower roll assembly that is the roll assembly on the side on which the vertical roll load measurement apparatuses are installed, as illustrated in
Note that, in the first adjustment, a bending force is applied between the intermediate rolls 41 and 42 and the backup rolls 3 and 4 using bending apparatuses of the intermediate rolls 41 and 42. At such time, the bending apparatuses of the work rolls 1 and 2 apply a bending force of a degree such that the intermediate rolls 41 and 42 and the work rolls 1 and 2 do not slip.
Next, in the second adjustment, firstly, with regard to the upper roll assembly that is the roll assembly on the side on which the vertical roll load measurement apparatuses are not installed, for example, as illustrated on the upper side in
On the other hand, with regard to the lower roll assembly that is the roll assembly on the side on which the vertical roll load measurement apparatuses are installed, as illustrated in
In the second adjustment, bending apparatuses of the work rolls 1 and 2 are used to apply loads between the work rolls 1 and 2 and the intermediate rolls 41 and 42. At such time, the bending apparatuses of the intermediate rolls 41 and 42 are set to zero or in a balanced state. Note that, in a case where the intermediate rolls 41 and 42 have a decrease bending apparatus, the decrease bending apparatuses may be caused to act in a direction (negative direction) such that the loads between the intermediate rolls 41 and 42 and the backup rolls 3 and 4 are removed.
Next, when the first process is completed, as illustrated in
Thus, the present invention is also applicable to a six-high rolling mill, and not just a four-high rolling mill. Furthermore, the present invention is similarly applicable to rolling mills other than a four-high rolling mill and a six-high rolling mill, and for example the present invention can also be applied to an eight-high rolling mill or a five-high rolling mill.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-041918 | Mar 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/008384 | 3/4/2019 | WO | 00 |
