JP3539320B2 - Speed control method and tracking method of transfer device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a speed control method and a tracking method of a transfer device used for transferring a high-temperature object such as an online cooling facility.
[0002]
[Prior art]
In the production of thick steel plates, heat treatment such as online accelerated cooling is performed mainly from the viewpoint of the material. In online accelerated cooling, cooling is performed by applying cooling water to the upper and lower surfaces while transporting a high-temperature steel plate on a transport table. The transport table has a large number of transport rolls arranged thereon and transports a steel plate.
[0003]
Rolls called draining rolls are installed above each of these transport rolls. The cooling water nozzle is installed between these draining rolls, and the cooling water injected onto the steel sheet surface is blocked by these draining rolls, flows in the width direction of the plate, and is collected in the cooling water pit. In this way, by preventing the flow of the cooling water in the front-rear direction, a decrease in the cooling efficiency due to the stagnation of the cooling water of the front and rear nozzles is prevented. The draining roll and the transport roll are driven by a drive motor because a steel plate is sandwiched between them by a constant force.
[0004]
In some cases, the tail end of the thick steel plate is warped upward. In this case, when the tail end passes through the draining roll, it jumps up and breaks the cooling water nozzle. In order to prevent this, it is desirable to track the position of the tail end with high accuracy, and to retract the cooling water nozzle immediately before passing the tail end.
[0005]
In general, the detection of the transport speed is performed by measuring the number of rotations of the transport roll or by a non-contact type speed detection method. Many non-contact speed detection methods use an optical detection method, and various methods are known.
[0006]
Japanese Patent Laying-Open No. 59-128110 proposes a speed control device of a transfer device which obtains a deviation between a set value of a transfer speed and a measured value and corrects the speed according to the difference. The speed control device according to this technology includes a speed controller that controls the speed of a motor that drives the transfer device to be equal to the speed command value, a transfer speed detector, a transfer speed setting device, and a setting value of the transfer speed. And a speed correction device for determining a value deviation and providing a speed command value according to the deviation.
[0007]
The detection of the transport speed is performed by a tracking device that runs at the same speed as the transported object. According to the embodiment of the gazette, according to the embodiment of the publication, the detection roller provided in the following device is caused to travel by itself at a speed of contacting the conveyed object and lightly pushing, and detecting the speed from the rotating roller of the following device. Things.
[0008]
Japanese Patent Application Laid-Open No. Sho 56-48319 proposes a transport table control device in which a plurality of table rollers are individually provided with weight detectors. In this technology, for each passing signal transmitted from the weight detector when the material is conveyed, the number of pulses is converted to calculate the moving distance, so that the slip between the conveyed object and the roller or uneven roller diameter is achieved. It is to reduce the impact.
[0009]
[Problems to be solved by the invention]
The conventional technique has a problem in detecting the transport speed. In the case of measuring the number of rotations of the transport roll, a slip between the transport roll and the transported object or a roll circumference error may occur, so that a very accurate transport speed cannot be detected.
[0010]
Further, the optical speed detection has the following problem. For example, when conveying a high-temperature steel sheet as in the case of online heat treatment of a steel sheet, the installation position of the optical sensor must be separated from the steel sheet due to problems such as protection of the detector from radiant heat. As a result, in a line in which a number of nozzles and other devices are installed, such as an online cooling device, the field of view of the optical sensor is obstructed, and speed detection becomes difficult. In addition, steam generated from the cooling water makes the conveyed object invisible and makes it impossible to detect the speed, so that speed control becomes difficult.
[0011]
In the technique described in JP-A-59-128110, a tracking device that moves at the same speed as a conveyed object is used for detecting a conveying speed, and therefore, equipment such as a moving rail and a driving device is required. In addition, since these facilities are incorporated in the transfer device, an installation space is required for the transfer device, which is not very realistic.
[0012]
In the technique described in Japanese Patent Application Laid-Open No. Sho 56-48319, it is necessary to individually provide a plurality of table rollers with a weight detector. Therefore, when this technology is used, there is a problem that a large amount of equipment cost is required to install the equipment.
[0013]
As described above, tracking of a thick steel plate in a transfer device such as online cooling has not always been performed with high accuracy due to a problem in equipment. For this reason, before the tail end of the thick steel plate passes through the draining roll, an operation of evacuating the cooling water nozzle with sufficient margin is performed, and cooling near the tail end may be insufficient. Further, when the cooling water nozzle is attached to the bearing of the draining roll or the like, the entire draining roll is evacuated, and there is a problem in that the cooling near the tail end is not uniform due to poor draining.
[0014]
The present invention solves the above-mentioned problems of the prior art, and realizes speed control of a transfer device capable of speed control even in the case of a slip between a transfer roll and a transfer object or a bad measurement environment such as online heat treatment. It is intended to provide a method and a tracking method.
[0015]
[Means for Solving the Problems]
The above problem is solved by the following invention.
[0016]
According to a first aspect of the present invention, in a speed control method of a transport device having a plurality of pairs of rolls contacting both upper and lower surfaces of a transported object, a rise in torque current is detected for a torque current of a drive motor of at least one of the upper and lower rolls. Calculating the transport speed of the transported article from the relationship between the detection time and the installation interval of the rolls, and correcting the speed set value according to the deviation from the roll speed set value. Is the way.
[0017]
According to the present invention, the transport speed is calculated by detecting the time at which the transported object passes through the roll pair by utilizing the characteristic of the transport device that the transported object is transported while contacting the roll pair. Here, a plurality of pairs of rolls that contact the upper and lower surfaces of the steel plate means that there are a plurality of pairs of rolls that contact the upper and lower surfaces of the steel plate.
[0018]
However, this pair of rolls does not deform the steel plate such as rolling. For example, a roll such as a pinch roll for keeping a steel sheet at a constant speed, or a roll provided with a draining roll such as online accelerated cooling corresponds to this.
[0019]
These rolls continue to rotate even when the steel sheet is not being conveyed, but the torque is basically zero, and the detected torque current is very small. When the steel plate contacts the roll, the torque current of the drive motor of the roll increases sharply. This rapid increase of the torque current, that is, the rise of the torque current can be easily detected by a differentiating circuit, a binarizing circuit, or the like. At this time, the time of the rise of the torque current, that is, the detection time, is recorded at the same time. This detection time is nothing but the time when the tip of the steel sheet passes through the pair of rolls.
[0020]
By obtaining the detection times for a plurality of roll pairs, the time required for the steel sheet to move from one roll pair to the next roll pair is determined. Since the distance (interval) between the roll pairs is known, the moving speed of the steel sheet between the roll pairs, that is, the transport speed can be calculated. Next, a deviation between the calculated transport speed and the roll speed set value is determined. By correcting the speed set value of each roll according to this deviation, the transport speed of the steel sheet can be made to match the target value.
[0021]
In this way, the transported object can be transported at the target speed even if there is a slip or roll circumference error between the transport roll and the transported object. Also, even when the measurement environment is poor due to radiant heat, steam, or the like as in online heat treatment, it is possible to control the speed of the conveyed material reliably.
[0022]
According to a second aspect of the present invention, in the tracking method of a transport device having a plurality of pairs of rolls contacting both upper and lower surfaces of a transported object, at least one of the upper and lower rolls is driven by a torque current of a driving motor, and the transported object is driven by each roll pair Detecting the timing of passing through the motor, calculating the pulse rate using the number of pulses from the drive motor and the roll interval between these timings, and calculating the position of the conveyed object. It is.
[0023]
Generally, the pulse rate can be calculated using the number of pulses per rotation of the roll and the roll circumference, but tracking using this pulse rate may be shifted due to a change in the roll circumference due to roll slip, abrasion, or the like. Therefore, in the present invention, the actual moving distance of the material per pulse, that is, the actual pulse rate is calculated. By using the pulse rate thus obtained to calculate the moving distance of the conveyed object, highly accurate tracking is performed.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the schematic diagram of FIG. The draining roll 1 is installed on the upper surface of the transported object 9. A transport roll 2 for transporting the transported object 9 is provided at a position opposed thereto, and the pair of rolls (hereinafter, referred to as a roll pair) 1 and 2 are brought into contact with upper and lower surfaces of the transported object 9. Are located in
[0025]
FIG. 1A shows a state in which the transported article 9 has arrived at the first pair of rolls 1 and 2. A curve 8 in the figure schematically represents a change in the torque current of the drive motor, and the horizontal axis corresponds to the position of the leading end of the conveyed object 9. The torque current of the drive motor (curve 8) is almost zero until the leading end of the conveyed article 9 reaches the pair of rolls 1 and 2, but rises rapidly upon arrival. Thereafter, the pair of rolls 1 and 2 sandwich the conveyed object 9, and a torque current corresponding to the driving torque flows.
[0026]
FIG. 1B shows a state in which the conveyed article 9 arrives at the next pair of rolls 1 and 2. As in the first roll pair 1, 2 (FIG. 1a), there is a sharp rise in the drive motor torque current (curve 8). In this way, as shown in FIGS. 1C and 1D, the rise of the torque current is sequentially detected for each roll pair (i-1st, ith).
[0027]
It is assumed that the detection time of the rise of the torque current is t _i , the time interval (t _i -t _i−1 ) is Δt _i, and the installation interval between the i-th roll pair and the preceding roll pair is ΔL _i . The conveying speed V _i of the transport of that from the previous roll pair (i-1 th) until the roll pair (i th) is expressed by the following equation.
V _i = ΔL _i / Δt _i (1)
[0028]
Next, the conveying speed V _i of the nearby roll pair, an average velocity (moving average). Expressed by the formula, the moving average of the conveyance velocity V _i of n to i-th pair of rolls (where n <i) is as follows.
Vave (i, n) = Σ _j V _{i−n + j} / n (2)
Here, Σ _j represents the sum of j from 1 to n.
[0029]
After the leading end of the conveyed object has passed through the final roll pair (N-th), the average speed Vave is as follows.
Vave = Vave (N, n) (3)
Alternatively, take the overall average until the end of the conveyed product passes through the final roll pair,
V _N = Σ _i V _i / (N−1) (4)
Is used as Vave. In this case, the speed correction may be turned off.
[0030]
The speed control uses a deviation ΔV between the measured average speed Vave and the speed set value Vref, as shown in FIG. The deviation ΔV is converted into a speed correction value ΔVcomp. Here, k in the figure is a proportional constant of the speed correction value ΔVcomp, and δ is a dead zone for maintaining the stability of the system.
[0031]
In the basic loop of the speed control, the difference between the speed setting value Vref and the actual speed Vfb is input to an ASR (speed control circuit) to perform feedback control. The speed setting value Vref is corrected with an error ΔVcomp such as a delay caused by the above-mentioned speed control to control the speed. Therefore, the transport speed can be more accurately brought close to the speed set value Vref.
[0032]
Next, an example of tracking of a transported object will be described. The procedure is shown in the block diagram of FIG. First, the biting (contact) timing of the tip of the steel plate is detected from the rise of the motor torque signal. During this time, the number of pulses from a predetermined drive motor is counted from the biting timing of the previous roll pair to the biting timing of that roll pair. The pulse rate (distance per unit pulse) is calculated from the counted number of pulses and the roll interval. The obtained pulse rate is calculated by the same method as described above, and the average pulse rate is calculated.
[0033]
Tracking of the position of the tip of the steel sheet is performed by integrating the pulses of the roll drive motor from the initial (entrance) roll biting timing. Similarly, tracking of the position of the rear end of the steel sheet is performed by subtracting a previously input actual length of the steel sheet from the position of the front end of the steel sheet. Alternatively, the pulse integration is performed from the timing at which the tail end is detected by the tracking sensor immediately before entering the facility.
[0034]
Here, the drive motor used for the calculation may be any roll drive motor as long as the roll is in contact with the steel plate. If the steel sheet is longer than the equipment length, it is desirable to use a pulse from the drive motor of the first (entrance) roll until the tip of the steel sheet reaches the last (exit) roll. Thereafter, after the rear end of the steel sheet has passed through the first (entrance) roll, a pulse from the drive motor of the last (outlet) roll may be used. If the steel plate is shorter than the equipment length, it may be switched to the second drive motor from the tip every time the tip is detected by the torque current.
[0035]
The method of calculating the pulse rate will be described below using mathematical expressions. Let p _i be the number of pulses at the interval between the roll pairs counted by detecting the rise of the torque current, and let ΔL _{i be} the installation interval between the i-th roll pair and the preceding roll pair. The pulse rate R _i from the preceding roll pair (i−1) to the roll pair (i) is expressed by the following equation.
R _i = ΔL _i / p _i (5)
[0036]
Next, an average speed (moving average) is obtained for the pulse rate R _i of the nearest roll pair. Expressing the equation, the moving average of n (where n <i) pulse rates R _i up to the i-th roll pair is as follows.
Rave (i, n) = Σ _j R _{i−n + j} / n (6)
Here, Σ _j represents the sum of j from 1 to n.
[0037]
After the leading end of the conveyed object has passed through the final roll pair (N-th), the average pulse rate Rave is as follows.
Rave = Rave (N, n) (7)
Alternatively, take the overall average until the end of the conveyed product passes through the final roll pair,
R _N = Σ _i R _i / (N−1) (8)
Is used as Rave.
[0038]
【The invention's effect】
In the present invention, the set speed of the roll is corrected by detecting the time at which the conveyed object passes through the pair of rolls and calculating the conveyed speed. Even if there is an error, it is possible to convey the article at the target speed. Also, even when the measurement environment is poor due to radiant heat, steam, or the like as in online heat treatment, it is possible to control the speed of the conveyed material reliably.
[0039]
In particular, in the on-line accelerated cooling device, the draining roll is evacuated as a measure against the warpage of the rear end portion of the steel sheet, and the timing is controlled with high precision by the present invention. Therefore, the position of the draining roll can be maintained until immediately before the rear end of the steel sheet comes off, and the cooling of the steel sheet is uniformized.
[0040]
As a result, the accuracy of the cooling time and cooling stop temperature in the online heat treatment equipment can be improved, and the yield can be improved, material defects can be reduced, and high-quality materials can be stably manufactured.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an embodiment of the invention.
FIG. 2 is a block diagram illustrating a speed control method.
FIG. 3 is a block diagram illustrating a tracking control method.
[Explanation of symbols]
Reference Signs List 1 draining roll 2 transport roll 8 torque current 9 transported object

Claims (2)

In the speed control method of the transfer device having a plurality of pairs of rolls that are in contact with the upper and lower surfaces of the conveyed object, the torque current of the drive motor of at least one of the upper and lower rolls, the rise of the torque current is detected, the detection time and the detection time A speed control method for a transfer apparatus, wherein a conveyance speed of a conveyed object is calculated from a relationship between roll installation intervals, and the speed set value is corrected according to a deviation from the roll speed set value. In a tracking method of a transport device having a plurality of pairs of rolls that contact both upper and lower surfaces of a transported object, a timing at which the transported object passes through each roll pair is detected from at least a rise in torque current of a drive motor of one of the upper and lower rolls. A method of calculating the pulse rate using the number of pulses from the drive motor and the roll interval during these timings to calculate the position of the conveyed object.

Images