Tension Control Device

Abstract

Provided is a tension control device capable of suppressing a speed overshoot of rolling stock after exiting a final rolling stand of a finishing mill, to improve the accuracy of a stopping position of a tail end of the rewound rolling stock. The tension control device controls the tension of the rolling stock when the rolling stock that has exited the final rolling stand of the finishing mill is being wound onto a mandrel via a pinch roll. The tension control device is configured to be capable of switching a rotational drive of the mandrel between speed control and current control. The tension control device comprises a selecting means for comparing a torque required for speed control and a torque required for current control and selecting the smaller torque as a final torque, and an integrator for integrating an output of the speed control, and is additionally provided with a limit setting unit for setting a limit corresponding to a tension reference for the integrator, the configuration being such that the output of the integrator does not become saturated.

Description

[Technical field]

[0001] The present disclosure relates to a tension control device that controls the tension of a rolled material when the rolled material has exited a final rolling stand of a finishing mill and is wound onto a mandrel via pinch rolls. [Background technology]

[0002] For example, a hot rolling plant includes a finishing mill having a plurality of rolling stands, and a winder having a pinch roll and a mandrel. The strip, which is the material to be rolled, rolled in the finishing mill is wound around the mandrel via the pinch roll. The pinch roll and the mandrel are speed-controlled for their rotational drive. Your visit and current control (Hereinafter referred to as "tension control") is used.

[0003] In another conventional tension control device described in Patent Document 1 below, the pinch rolls and mandrel are driven under speed control until the leading end of the strip, which is the material to be rolled, reaches the mandrel, and when the leading end of the strip reaches the mandrel, the drive of the pinch rolls and mandrel is switched from speed control to tension control (current control).When the tail end of the strip leaves the final rolling stunt of the finishing mill, the drive of the mandrel is switched from tension control (current control) to speed control, thereby preventing a sudden increase in the speed of the strip.

[0004] The mandrel speed control and tension control are performed based on signals sent to the tension control device from a higher-level computer (hereinafter also referred to as the "main") such as a PLC (Programmable Logic Controller). These signals include the main tension setting B_ST, speed reference SP_REF, and tension reference TENS_REF, as shown in Figs. 6 and 7. The main tension setting B_ST is a bit signal that switches tension control on and off. The speed reference SP_REF is the set speed of the mandrel, and the actual speed SP _When the main tension setting B_ST is turned on, the selection means MIN shown in Fig. 6 compares the torque required for speed control (speed control torque reference) and the tension reference TENS_REF, which is the torque required for tension control, input from the comparator 110, and selects the smaller one as the output torque.

[0005] Here, in order to ensure the tension of the strip, the actual speed SP _ It is necessary to set the speed reference SP_REF to a value larger than FBK. Therefore, the integration by the integrator 112 shown in Fig. 7 is performed up to the motor torque limit value set as an internal parameter, and as a result, the I component (integration) increases up to the motor torque limit value and is saturated. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 7-75824 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the above-mentioned conventional example, when the rolled material exits the final rolling stand, the pinch rolls are speed-controlled, whereas the mandrels are Tension control ( Current Control )Therefore, the speed of the rolled material increases rapidly due to slippage of the pinch rolls, which occurs especially when the pressing force of the pinch rolls against the rolled material is weak or when the tension setting of the mandrel is high. Then, the speed control integrator, which integrates the speed output, is saturated, and only when the actual speed SP_FBK falls below the speed reference SP_REF does it attempt to control in the deceleration direction. As a result, the material speed significantly overshoots, as shown by the double-dashed line in FIG. 8. During the overshoot, speed control cannot be performed, which leads to a deterioration in the accuracy of the stopping position of the tail end of the rolled material being wound, and in some cases, the material must be re-wound.

[0008] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a tension control device that can improve the accuracy of the stopping position of the tail end of the rolled material being wound by suppressing the speed overshoot of the rolled material after it leaves the final rolling stand of the finishing rolling mill. [Means for solving the problem]

[0009] The present disclosure relates to a tension control device that controls the tension of a rolled material when the rolled material leaves a final rolling stand of a finishing mill and is wound around a mandrel via pinch rolls. Electric motor Rotation drive with speed and current control Tension control The tension control device is configured to be able to switch between the torque required for speed control and the torque required for current control, and selects the smaller torque. Electric motor A selection means for selecting a torque as a final torque and an integrator for integrating an output of the speed control, , which corresponds to the tension reference, which is the torque required for tension control The present invention further includes a limit setting section for setting a limit, so that the output of the integrator is not saturated. Effect of the Invention

[0010] According to the present disclosure, by setting a limit for an integrator that integrates the output of the speed control, the torque required for the speed control is selected by the selection means before the output of the integrator becomes saturated. This suppresses speed overshoot of the rolled material after it leaves the final rolling stand of the finishing mill. In other words, the speed of the rolled material is able to follow the speed reference more easily after the tail end of the rolled material leaves the final rolling stand. Therefore, the tail end of the rolled material wound around the mandrel can be stopped with high accuracy. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing a configuration of a rolling plant to which a tension control device according to an embodiment is applied; [Diagram 2] FIG. 2 is a block diagram showing a schematic function of a tension control device according to an embodiment. [Diagram 3] 4 is a time chart illustrating speed control in the embodiment. [Figure 4] 13A is a graph showing actual speeds relative to a speed reference in the embodiment, and FIG. 13B is a graph showing actual speeds relative to a speed reference in the conventional example. [Diagram 5] FIG. 2 is a conceptual diagram illustrating an example of a hardware configuration of a processing circuit included in the tension control device. [Figure 6] FIG. 2 is a conceptual diagram illustrating an example of a hardware configuration of a processing circuit included in the tension control device. [Figure 7] FIG. 11 is a block diagram showing a schematic function of a tension control device according to a conventional example. [Figure 8] 5 is a time chart illustrating speed control in a conventional example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that elements common to the various drawings are designated by the same reference numerals and duplicated explanations will be omitted. [Rolling plant]

[0013] FIG. 1 is a block diagram of a Tension Control 1 is a schematic diagram showing the configuration of a rolling plant 1 to which the apparatus is applied. The rolling plant 1 takes slabs and strips of steel or other metal materials as rolled material M and hot rolls the material M into a plate shape.

[0014] The rolling plant 1 is equipped with, as its main equipment, a heating furnace 2, a roughing mill 3, a crop shear 4, a finishing mill 5, a cooling device 6, and a winder 7.

[0015] The heating furnace 2 heats a rectangular slab, which is the material M to be rolled before rolling, to a predetermined temperature (for example, 1200°C). The roughing mill 3 has at least one rolling stand, and usually one to three rolling stands, and rolls the material M heated in the heating furnace 2 in a forward direction (from upstream to downstream of the rolling line) and a reverse direction (from downstream to upstream of the rolling line) for multiple passes. The crop shear 4 cuts off defective parts of the front or tail end of the material M to be rolled with upper and lower blades.

[0016] The finishing mill 5 is a tandem rolling mill equipped with N rolling stands Fi (1≦i≦N) arranged in parallel in the conveying direction of the material M to be rolled. In this embodiment, seven rolling stands F1 to F7 are arranged in parallel, and the final rolling stand is F7. Each of the rolling stands F1 to F7 is equipped with two work rolls 51, one above the other, two backup rolls 52, one above the other, and an electric motor 53 for driving the rolls. The backup rolls 52 are provided with a reduction device 54, which can adjust the gap between the upper and lower work rolls 51 (hereinafter simply referred to as "gap"). The rolling load of each of the rolling stands F1 to F7 is measured by a rolling load sensor 55. The cooling device 6 is configured to inject water into the material M to be rolled by a cooling bank, thereby cooling the material M to be rolled. The cooled material M to be rolled is wound into a coil by a winder 7.

[0017] The winding machine 7 includes one or more (one in this embodiment) pinch rolls 71, one or more (one in this embodiment) mandrels 72, an electric motor 73 for driving the rotation of the pinch rolls, an electric motor 74 for driving the rotation of the mandrels, and a pulse generator (PLG) 75. Note that a winding guide (not shown) for guiding the rolled material M to the pinch rolls 71 and the mandrel 72 may be provided.

[0018] Various sensors as measuring instruments are installed at key points in the rolling plant 1. The various sensors include the rolling load sensor 55, the pulse generator (PLG) 75, an end detection sensor 8 that detects the leading or trailing end of the rolled material M at the exit side of the final rolling stand F7, and the like. The various sensors sequentially measure the state of the rolled material M and each piece of equipment.

[0019] The rolling plant 1 is operated by a control system using a computer. The computer includes a host computer 10 and a process control computer 11, which are connected to each other via a network. The host computer 10 is, for example, a PLC (Programmable Logic Controller). An interface screen 12, which is an operation screen operated by an operator, is connected to the process control computer 11 via the network.

[0020] The process control computer 11 executes setting calculation and control of control objects in a series of rolling processes. The process control computer 11 receives inputs from the host computer 10 of slab information such as thickness, width, length, steel type, etc. of the slab which is the material to be rolled M before rolling, coil target information such as target thickness, target width, target temperature, etc. of the strip which is the material to be rolled M after rolling, and rolling setup information such as the gap of each rolling stand F1 to F7 of the finishing rolling mill 5.

[0021] In this embodiment, the process control computer 11 has a function of controlling the tension of the rolled material M wound around the mandrel 72. That is, the process control computer 11 can also function as a tension control device. The tension control device 11 has a function as a driver (amplifier) ​​that controls the electric motor (motor) 74. Although not shown, the tension control device 11 has a selection means MIN shown in FIG. 6.

[0022] Fig. 2 is a block diagram showing a schematic configuration of the tension control device 11. Fig. 3 is a time chart illustrating the speed control by the tension control device 11.

[0023] The tension control device 11 receives winding information, which is information related to winding, from the host computer 10. The winding information includes, for example, a trunk tension setting B_ST, a speed reference SP_REF, and a tension reference TENS_REF. The trunk tension setting B_ST is a bit signal that switches tension control on / off. The speed reference SP_REF is the set speed for speed control. The tension reference TENS_REF is a trunk torque reference.

[0024] When the main tension setting B_ST input from the host computer 10 to the tension control device 11 is turned on, the tension control device 11 also receives the speed reference SP_REF from the host computer 10. At this time, the value of the speed reference SP_REF is set to be greater than the value of the actual speed SP_FBK fed back from the PLG 75. This makes the torque required for speed control (speed control torque reference) greater than the tension reference TENS_REF, which is the torque required for tension control. Then, the comparator 110 compares the speed reference SP_REF with the actual speed SP_FBK to find the difference between them. The adder 111 multiplies the difference output from the comparator 110 by a predetermined coefficient (proportional gain) Kp to obtain a P portion (proportional portion), and multiplies the difference by a predetermined coefficient Ki. Ride The calculated value is integrated by the integrator 112 and the integrated value is added to the I portion (integration). Note that 800% in Fig. 2 is the maximum limit value set in the rolling plant 1. The integrator 112 continues the integration (integration) until the motor torque limit detection unit 113 detects a motor torque limit that is set in advance.

[0025] The tension control device 11 also includes a limit setting unit 114. When the trunk tension setting B_ST is turned on, the limit setting unit 114 sets a limit value equivalent to the tension reference (torque reference) TENS_REF for the integrator 112. This causes the I component integrated by the integrator 112 to peak out at the tension reference (main trunk torque reference) TENS_REF. In other words, the I component of the integrator 112 is limited before it becomes saturated. On the other hand, in the conventional example shown in FIG. 8, the I component of the integrator 112 exceeds the tension reference (main trunk torque reference) TENS_REF and becomes saturated.

[0026] Thereafter, when the tail end of the material M to be rolled leaves the final rolling stand F7, the actual speed SP_FBK, which had been constant up until then, begins to increase. Here, because the I component is suppressed as described above, the overshoot of the actual speed SP_FBK is smaller than in the conventional example. This makes it shorter than in the conventional example for the final output of the suppression drive to fall below the tension reference (torque reference) TENS_REF. As a result, it is possible to switch from tension control to speed control in a short time after the tail end of the material M to be rolled leaves the final rolling stand F7.

[0027] As described above, according to this embodiment, by setting a limit equivalent to the tension reference (torque reference) TENS_REF for the integrator 112 that integrates the output of the speed control, the selection means MIN selects the torque required for the speed control before the output of the integrator 112 is saturated. As a result, as shown in FIG. 4(a), after the time t1 when the material M leaves the final rolling stand F7 of the finishing mill 5, the speed overshoot of the material M is suppressed more than in the conventional example (see FIG. 4(b)). As a result, it was confirmed that the trackability of the actual speed SP_FBK of the material M measured by the PLG75 to the speed reference SP_REF after the time t1 is improved. Therefore, the tail end of the material wound around the mandrel can be stopped with high accuracy.

[0028] The specific structure of the tension control device 11 is not limited, but may be as follows, for example. FIG. 5 is a diagram showing an example of the hardware configuration of the processing circuit 20 of the tension control device 11. The functions of the tension control device 11 can be realized by the processing circuit 20 shown in FIG. 5. The processing circuit 20 may be dedicated hardware 20a. The processing circuit 20 may include a processor 20b and a memory 20c. The processing circuit 20 may be partially formed as dedicated hardware 20a, and further include a processor 20b and a memory 20c. In the example of FIG. 5, a part of the processing circuit 20 is formed as dedicated hardware 20a, and the processing circuit 20 also includes a processor 20b and a memory 20c.

[0029] At least a portion of the processing circuitry 20 may be at least one dedicated hardware 20a, such as a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

[0030] The processing circuit 20 may include at least one processor 20b and at least one memory 20c. In this case, each function of the tension control device 11 is realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in the memory 20c. The processor 20b realizes the functions of each part by reading and executing the programs stored in the memory 20c.

[0031] The processor 20b is also called a CPU (Central Processing Unit), central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP. The memory 20c corresponds to, for example, a non-volatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM. In this way, the processing circuit 20 can realize each function of the tension control device 11 by hardware, software, firmware, or a combination of these.

[0032] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and can be modified in various ways without departing from the spirit of the present invention. The configuration of the rolling plant is not limited to the example shown in FIG. 1, and the present invention can be applied to rolling plants with various modified configurations. In addition, when the number, quantity, amount, range, etc. of each element is mentioned in the above embodiment, the present invention is not limited to the mentioned number, unless otherwise specified or clearly specified in principle. For example, the winding machine 7 may include two or three pinch rolls 71 and mandrels 72. In addition, the structures and the like described in the above embodiment are not necessarily essential to the present invention, unless otherwise specified or clearly specified in principle. [Explanation of symbols]

[0033] 1... rolling plant, M... material to be rolled, MIN... selection means, 11... tension control device, 112... integrator, 114... limit setting unit, 71... pinch roll, 72... mandrel

Claims

[Claim 1] A tension control device controls the tension of a rolled material when the rolled material has left the final rolling stand of a finishing rolling mill and is wound around a mandrel via pinch rolls, the tension control device being capable of switching the rotation drive of the mandrel motor between speed control and tension control which is current control, a selection means for comparing a torque required for the speed control with a torque required for the tension control and selecting the smaller torque as the final torque of the motor; an integrator that integrates the output of the speed control; The tension control device further comprises a limit setting unit that sets a limit for the integrator that corresponds to a tension reference, which is a torque required for the tension control, so as not to saturate the output of the integrator.

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