JPH0217683Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a speed control device for a pinch roll in front of a winder in a hot strip mill for steel or the like.

Problems with the Prior Art The pinch roll control device of the winder of a hot strip mill generally uses a speed control device as shown in Figure 1 to ensure speed consistency with respect to the moving speed of the steel plate. There is. In the figure, 1 is a steel plate, 2 is a finishing stand, 31 and 32 are pinch rolls, 41 and 42 are direct current motors (DCM) that drive the pinch rolls, and 5
is the winding machine, 6 is the DCM for the winding machine, 71, 72
8 is a speed control device, and 8 is a tension control device. In the control system of the winding machine with such a configuration, the speed control device 7 normally controls the speed at a predetermined speed so that even if the speed of the finishing stand 2 or the winding machine 5 suddenly changes due to other factors, uniform speed can be maintained. It has looping. Here, dowlooping refers to "drooping characteristics"
This is also called a speed controller, and means that the relationship expressed by the following equation (1) is established between the speed command, the speed feedback signal, and the current.

V=Vref-I・K...(1) V: Speed feedback signal Vref: Speed command I: Current K: Constant (referred to as dow looping amount) The relationship in equation (1) above is illustrated in Figure 4.

By providing such a draw looping characteristic, when the load suddenly changes, the speed feedback signal V changes in accordance with the increase in the current I, so that it has a smooth follow-up characteristic.

On the other hand, if the draw looping characteristic is not added, if a sudden change in load occurs, the speed command
A rapid fluctuation occurs in the current I to maintain Vref.

When the pinch roll of a down coiler is provided with this dew looping characteristic, when the steel plate is being wound on the mandrel and is caught in the finishing stand, this dew looping characteristic will cause the difference between the pinch roll speed command and the plate speed. Even if there is a difference between the two, the speed feedback signal V increases or decreases in accordance with the difference, so that the current can be kept within an appropriate range without causing an excessive current to flow through the pinch roll (see FIG. 5). In this way, by providing the speed control device 7 with draw looping, even if the speed of the finishing stand 2 or the winding machine 5 changes suddenly, the steel plate 1 and the pinch rolls 31, 32 can maintain uniform speed, thereby preventing slips, scratches, etc. can be prevented from occurring. However, the following problems arise due to the provision of this dowel looping.

First of all, the first problem is that the DCM 4 at the time when the tip of the steel plate 1 is caught in the pinch rolls 31 and 32.
The rise characteristics of the load currents 1 and 42 are worse as shown in Fig. 3 compared to the case without dowel looping, and therefore
The accuracy of detection of jamming deteriorates.

Next, the second problem is that when the tail end of the steel plate 1 passes through the finishing stand 2, all the winding tension of the mandrel is applied to the pinch rolls, causing a sudden increase in motor load, as shown in Fig. 6. As a result, it is necessary to pass a large reverse current through the pinch roll. If dough looping is present at this time, the pinch rolls will accelerate and the winding speed will increase. If the winding speed of the steel plate increases, it may have an adverse effect on the winding temperature control, or cause edge breakage due to fluttering of the tail end of the steel plate 1.

Purpose of the invention This invention was made to solve the above problems, and it maintains uniform speed between the steel plate and the pinch roll, improves the accuracy of detecting the tip of the steel plate biting into the pinch roll, and improves the accuracy of detecting the tip of the steel plate caught in the pinch roll. This is to stabilize the winding speed of the steel plate after the end of the finishing stand is removed.

Structure of the Invention In order to achieve the above object, the present invention provides a pinch roll speed control for a hot strip mill having a DC motor for driving a pinch roll, a speed control calculator, a current control calculator, and a draw looping setting device. The speed control device for a pinch roll is provided with a switching controller and a switch for switching on/off the dowlooping output from the dowelooping setting device to the speed control calculator.

Effects of the invention and embodiments The invention will be described in detail below with reference to the accompanying drawings. FIG. 2 is a block diagram showing an embodiment of a speed control device for a pinch roll in a hot strip mill according to the present invention. In the figure, 12 is a speed control calculator (ASR), 14 is a current control calculator (ACR), 15 is a phase controller (PHC), 16 is a thyristor (SCR), 41 is a pinch roll drive (DCM), 17 is a current detector (CT), 18 is a rotation speed detector (TG), 19 is a dowel looping setter, 20 is a relay contact, and 21 is the relay contact 2
0 is a switching controller, 11 and 13 are adders. The operation of a speed control device having such a configuration when used in a pinch roll of a hot strip mill will be described below.

First, the relay contact 20 is opened until the tip of the steel plate 1 is bitten by the pinch rolls 31 and 32.
Dew looping to the ASR 12 is cut off, and after the biting, the relay contact 20 is closed to perform dow looping to the ASR 12. Next, when the tail end of the steel plate 1 passes through the finishing stand 2, the relay contact 2
Set it to 0 and turn off the dowel looping. Note that the relay contact 20 is opened and closed by transmitting a timing signal from the master control section to the switching controller 21 and outputting a switching command signal to the relay contact 20.

By performing the above action on the relay contact 20, the tip of the steel plate 1 is fixed to the pinch rolls 31, 32.
There was no dowel looping until it bit into the
Since the DCM 41 is driven, the load current of the DCM 41 when the tip of the steel plate 1 is bitten rises rapidly as shown in FIG. 3, so that the biting detection accuracy is greatly improved. In addition, during the period from when the leading end of the steel plate 1 is wound up by the winding machine 5 to when the tail end passes through the finishing stand 2, the DOM 41 is driven in a state with dowel looping as in the past, so that the finishing stand 2 and the winding It is possible to wind the film while maintaining desired speed uniformity with respect to the winding machine 5. Furthermore, since the DCM 41 is driven in the dow looping state after the tail end of the steel plate 1 passes through the finishing stand 2, it is possible to reliably respond to an increase in the speed of the steel plate 1 and prevent speed change fluctuations.

Although a relay contact is used as the switch in the present invention, other means may be used.

Effects of the invention When the pinch roll speed control device according to the invention is applied to a hot strip mill, the following effects can be achieved. First, since the accuracy of detecting pinch roll jamming at the tip of the steel plate is improved, it is possible to prevent troubles in winding machine control due to erroneous detection. Also,
During normal winding, dowel looping maintains uniform speed and prevents slip defects between the steel plate and the pinch roll. Furthermore, after the tail end of the steel plate passes through the finishing stand, the steel plate is driven with the dowel looping cut off, which prevents speed fluctuations in the steel plate.As a result, the accuracy of winding temperature control at the tail end of the steel plate can be improved. It is possible to prevent the occurrence of edge breakage, etc. due to flapping of the tail end of the steel plate.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the control system of the winding machine in a hot strip mill, Fig. 2 is a block diagram of the speed control device of the pinch roll, and Fig. 3 is a diagram showing changes in the load current of the pinch roll DCM. Figure 4 is a diagram showing the relationship between the speed command, speed feedback signal, and current in the speed control device of the pinch roll, and Figure 5 is the effect of the draw looping characteristic when the steel plate is caught in the finishing stand during winding. FIG. 6 is a diagram showing changes in pinch roll current depending on the presence or absence of dow looping after the steel plate passes through the finishing stand. 1... Steel plate, 2... Finishing stand, 31, 32
... Pinch roll, 41, 42 ... DCM for pinch roll, 5 ... Winding machine, 6 ... For winding machine
DCM, 71, 72... Speed control device, 8... Tension control device, 11, 13... Adder, 12...
ASR, 14...ACR, 15...PHC, 16...
SCR, 17...CT, 18...TG, 19...Door looping setting device, 20...Relay contact, 21
...Switching controller.

Claims (1)

[Scope of utility model registration request] In a pinch roll speed control device for a hot strip mill having a DC motor for driving a pinch roll, a speed control calculator, a current control calculator, and a dowel looping setting device, from the dowel looping setter to the speed control calculator A pinch roll speed control device comprising a switching controller and a switching device for turning on and off the dowel looping output.