Patent Application
20210220883
The present invention relates to a control apparatus of a tandem rolling mill.
PTL 1 discloses a control apparatus of a tandem rolling mill. According to the control apparatus, rupture of a rolled material may be prevented with use of a Droop function (motor speed command reduction rate with respect to motor current of 100%) with respect to a plurality of stands when the tandem rolling mill is activated.
[PTL 1] JP S60-3910 A
The control apparatus disclosed in PTL 1, however, does not consider difference in a load due to mechanical rattle among the plurality of stands when the tandem rolling mill is activated. Therefore, a large difference in speed of rolls may in some cases occur between the adjacent stands due to the Droop function. As a result, the rolled material ruptures in some cases.
The present invention has been made to solve the above-described issues. An object of the present invention is to provide a control apparatus of a tandem rolling mill that makes it possible to more surely prevent rupture of a rolled material.
A control apparatus of a tandem rolling mill according to the present invention includes a speed command output unit configured to temporarily output a speed command value to each of a plurality of stands before a tandem rolling mill is activated while in a state where a rolled material is sandwiched between the plurality of stands, and a Droop amount setting unit configured to set a Droop amount set value of the stand smaller toward rear stage of the plurality of stands, during a period in which the speed command output unit temporarily outputs the speed command value.
A control apparatus of a tandem rolling mill according to the present invention includes a torque command output unit configured to temporarily output a torque command value to each of a plurality of stands before a tandem rolling mill is activated while in a state where a rolled material is sandwiched between the plurality of stands, and a Droop amount setting unit configured to set a Droop amount set value of the stand smaller toward rear stage of the plurality of stands, during a period in which the torque command output unit temporarily outputs the torque command value.
According to the invention, the Droop amount set value of the stand becomes smaller toward the rear stage when the plurality of stands are temporarily operated before activation of the tandem rolling mill. Therefore, appropriate tension is applied to the rolled material between the adjacent stands while a load corresponding to the mechanical rattle of the plurality of stands is absorbed. As a result, it is possible to more surely prevent rupture of the rolled material.
An embodiment of the present invention is described with reference to accompanying drawings. Note that, in the drawings, identical or equivalent parts are denoted by the same reference numerals. Overlapped description of the parts is simplified or omitted as necessary.
In the cold tandem rolling mill in
The control apparatus 6 outputs a speed command value to each of the plurality of drive devices 5. Each of the plurality of drive devices 5 rotates the corresponding motor 4 based on the speed command value from the control apparatus 6. In each of the plurality of stands 1, the paired work rolls 2 are rotated following rotation of the corresponding motor 4. The plurality of backup rolls 3 are rotated following the paired work rolls 2. As a result, a rolled material 7 is rolled in an arrow direction.
Next, the control apparatus 6 is described with reference to
As illustrated in
The speed command output unit 6a outputs the speed command value to each of the plurality of stands 1. The Droop amount setting unit 6b outputs a Droop amount set value to each of the plurality of stands 1. As a result, loads applied to the plurality of stands are balanced.
Next, speed control before and after the cold tandem rolling mill is activated is described with reference to
As illustrated in
During the period in which the speed command output unit 6a temporarily outputs the step-shaped speed command value a, the Droop amount setting unit 6b outputs a Droop set value D0 to each of the plurality of stands 1. At this time, the Droop amount setting unit 6b sets the Droop amount set amount D0 of the stand 1 smaller toward the rear stage. As a result, appropriate tension is applied to the rolled material 7 between the adjacent stands 1 while the load corresponding to mechanical rattle of the plurality of stands 1 is absorbed.
In a subsequent time period T2, the Droop amount setting unit 6b outputs a Droop amount set value 0 in consideration of necessity of torque for activation because of static friction of bearings of the backup rolls 3.
After the time period T2 elapses, the speed command output unit 6a outputs the speed command value for simultaneous activation to all of the plurality of stands 1. At this time, a speed PI successive control is performed in consideration of difference in static friction coefficients of the bearings of the backup rolls 3 among the plurality of stands 1. More specifically, a difference between the tension response value and a tension reference value of the rolled material between the adjacent stands 1 is suppressed. For example, in a case where the rolled material is slightly pulled, when the speed command value of each of the stands 1 is increased, the rolled material is loosened. For example, in a case where the rolled material is slightly loosened, when the speed command value of each of the stands 1 is reduced, the rolled material is pulled.
Thereafter, at a time when the speed response value becomes a start-completion speed Vo in each of the plurality of stands 1, the Droop amount setting unit 6b outputs a Droop amount set value D1. At this time, the Droop amount set value D1 is set to a value larger than the Droop amount set value D0. Thereafter, the Droop amount setting unit 6b maintains the Droop amount set value D1 until the speed command value becomes a Droop amount maintaining speed V1.
Thereafter, the Droop amount setting unit 6b gradually reduces the Droop amount set value until the speed command value becomes a minimum set speed V3 through a minimum rolling speed V2. More specifically, when the speed command value indicates the minimum rolling speed V2, the Droop amount setting unit 6b outputs the Droop amount set value D2. When the speed command value indicates the minimum set speed V3, the Droop amount setting unit 6b outputs the Droop amount set value 0. As a result, unbalancing of the speed due to the mechanical rattle among the plurality of stands 1 is suppressed in a low speed range, and appropriate tension is maintained on the rolled material 7 between the adjacent stands 1.
Next, a Droop amount setting method by the Droop amount setting unit 6b is described with reference to
As illustrated in
The Droop amount setting unit 6b determines the Droop amount set value based on the information in the Droop amount table. More specifically, the Droop amount setting unit 6b sets the Droop amount set value to “D1” when the speed command value is within a range from “V0” to “V1”. The Droop amount setting unit 6b sets the Droop amount set value to “D2” when the speed command value indicates “V2”. The Droop amount setting unit 6b sets the Droop amount set value to “0” when the speed command value indicates “V3”.
Next, speed control when the cold tandem rolling mill is stopped is described with reference to
As illustrated in
Next, adjustment of the Droop amount set value by the Droop amount setting unit 6b is described with reference to
As illustrated in
In this case, when the tension response value is smaller than the tension reference value between the adjacent stands 1, the Droop amount set value becomes smaller than the value obtained from the Droop amount table. In contrast, when the tension response value is larger than the tension reference value between the adjacent stands 1, the Droop amount set value becomes larger than the value obtained from the Droop amount table. As a result, unbalancing of the speed between the adjacent stands 1 is suppressed, and appropriate tension is maintained on the rolled material 7 between the adjacent stands 1.
According to the embodiment 1 described above, in the cold tandem rolling mill in the state where the plurality of stands 1 each sandwich the rolled material 7, the Droop amount setting unit 6b sets the Droop amount set value of the stand smaller toward the rear stage during the period in which the speed command output unit 6a temporarily outputs the speed command value. More specifically, the Droop amount set value is set so as to be inversely proportional to the speed of the stand 1 on the rear-stage side based on the speed of the stand 1 on the front-stage side. In this case, appropriate tension is applied to the rolled material 7 between the adjacent stands 1 while the load corresponding to the mechanical rattle of the plurality of stands 1 is absorbed. As a result, it is possible to more surely prevent rupture of the rolled material.
Further, the Droop amount setting unit 6b varies the Droop amount of each of the plurality of stands 1 based on the speed of each of the plurality of stands 1 after the cold tandem rolling mill is started, and adds the constant value β to the Droop amount set value corresponding to the speed of each of the plurality of stands 1 immediately before the cold tandem rolling mill is stopped. Accordingly, it is possible to suppress unbalancing of the speed due to the mechanical rattle among the plurality of stands 1 in the low speed range, and to stop the cold tandem rolling mill while the tension on the rolled material 7 is appropriately maintained between the adjacent stands 1. As a result, it is possible to more surely prevent rupture of the rolled material 7 when the cold tandem rolling mill is reactivated.
Note that control similar to the control according to the embodiment may be performed on a cold tandem rolling mill subjected to torque control. Also in this case, it is possible to more surely prevent rupture of the rolled material 7.
Next, an example of the control apparatus 6 is described with reference to
Functions of the control apparatus 6 may be implemented by a processing circuitry. For example, the processing circuitry includes at least one processor 100a and at least one memory 100b. For example, the processing circuitry includes at least one dedicated hardware 200.
When the processing circuitry includes the at least one processor 100a and the at least one memory 100b, the functions of the control apparatus 6 are implemented by software, firmware, or a combination of software and firmware. At least one of the software and the firmware is described as a program. At least one of the software and the firmware is stored in the at least one memory 100b. The at least one processor 100a reads and executes the program stored in the at least one memory 100b to implement the functions of the control apparatus 6. The at least one processor 100a is also referred to as a central processing unit, a processing device, a calculation device, a microprocessor, a microcomputer, or a DSP. For example, the at least one memory 100b is a nonvolatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, and EEPROM, a magnetic disk, a flexible disk, an optical disk, a compact disc, a mini disc, or a DVD.
When the processing circuitry includes the at least one dedicated hardware 200, the processing circuitry is implemented by, for example, a single circuitry, a composite circuitry, a programmed processor, a parallel-programmed processor, an ASIC, an FPGA, or a combination thereof. For example, the functions of the control apparatus 6 is individually implemented by the processing circuitry. For example, the functions of the control apparatus 6 are collectively implemented by the processing circuitry.
A part of the functions of the control apparatus 6 may be implemented by the dedicated hardware 200, and the other part may be implemented by the software or the firmware. For example, the function of the Droop amount setting unit 6b may be implemented by the processing circuitry as the dedicated hardware 200, and the functions other than the function of the Droop amount setting unit 6b may be implemented by causing the at least one processor 100a to read and execute the program stored in the at least one memory 100b.
As described above, the processing circuitry implements the functions of the control apparatus 6 by the hardware 200, the software, the firmware, or a combination thereof.
As described above, the control apparatus of the tandem rolling mill according to the present invention is usable in the tandem rolling mill.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2018/045752 | 12/12/2018 | WO | 00 |
