JP2000229722A - Conveyer speed control method and tracking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conveyer speed control method and a tracking method capable to control speed even in bad measuring environment of such as slip of conveyer roller and on-line heat treatment. SOLUTION: In a speed control method of a conveyer having multiple pares of rollers 2 contacting on both top and bottom surfaces of a conveyed object 9, about a torque electric current 8 of a drive motor of at least one of top and bottom rollers 2, a rise of the torque electric current 8 is detected, then a conveying speed of the conveyed object 9 is calculated from a relation between the detected time and a roller 2 arrangement interval. Based on a difference from a roller 2 speed set value, the speed set value is corrected. In the same manner, a timing when the conveyed object 9 passes through each roller 2 pair is detected form the rise of the torque electric current 8, then a pulse rate is calculated from the number of pulses generated from the drive motor and the roller 2 interval, and a location of the conveyed seat is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] 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]

2. Description of the Related Art In the production of steel plates, heat treatment such as on-line accelerated cooling is performed mainly from the viewpoint of materials. 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 plate 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 cooling water from flowing in the front-rear direction, the cooling efficiency of the front and rear nozzles due to stagnation of the cooling water 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.

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. To prevent this, track the position of the tail end with high accuracy,
It is desirable to evacuate the cooling water nozzle immediately before passing the tail end.

Generally, the detection of the transport speed is performed by measuring the number of revolutions 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.

Japanese Patent Application Laid-Open No. Sho 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 is a speed controller that controls the speed of the motor driving the transfer device to be equal to the speed command value, a transfer speed detector, a transfer speed setting device,
A speed correction device is provided for determining a deviation between the set value of the transport speed and the measured value and providing a speed command value according to the deviation.

[0007] The conveyance speed is detected by a tracking device which runs at the same speed as the conveyed 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.

Japanese Unexamined Patent Publication 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]

In the prior art, there is a problem in detecting the transport speed. In the case of measuring the number of rotations of the transport roll, it is not possible to detect the transport speed with high accuracy because there is a slip between the transport roll and the transported object and a roll circumference error.

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 where many nozzles and other equipment are installed, such as an online cooling device,
The field of view of the optical sensor is obstructed, making speed detection difficult.
In addition, steam generated from the cooling water makes the conveyed object invisible and makes speed detection impossible, so that speed control becomes difficult.

In the technique described in Japanese Patent Application Laid-Open No. 59-128110, a tracking device that moves at the same speed as a conveyed object is used for detecting the conveying speed, so that equipment such as a moving rail and a driving device are required. It is. 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.

In the technique described in Japanese Patent Application Laid-Open No. Sho 56-48319, it is necessary to provide a plurality of table rollers with individual weight detectors. Therefore, when this technology is used, there is a problem that a large amount of equipment cost is required to install the equipment.

As described above, tracking of a thick steel plate in a transfer apparatus 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 must be evacuated, and there is a problem that the cooling near the tail end is not uniform due to poor draining.

The present invention solves the above-mentioned problems of the prior art, and a transfer apparatus capable of controlling the speed even when the measurement environment is poor such as slippage between a transfer roll and a transfer object or on-line heat treatment. It is an object of the present invention to provide a speed control method and a tracking method.

[0015]

The above problem is solved by the following invention.

According to a first aspect of the present invention, there is provided a speed control method for a transporting apparatus having a plurality of pairs of rolls contacting the upper and lower surfaces of a transported object, wherein the torque current of at least one of the upper and lower roll driving motors is increased. Transport apparatus, wherein the transport speed of the transported article is calculated from the relationship between the detection time and the roll installation interval, and the speed set value is corrected according to the deviation from the roll speed set value. Speed control method.

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. I have. 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.

However, the pair of rolls do not deform the steel sheet 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.

Although these rolls continue to rotate even when the steel sheet is not being conveyed, the torque is basically zero and the detected torque current is very small. When the steel plate comes into contact with the roll, the torque current of the drive motor of the roll sharply increases. 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 roll pair.

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 can be 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.

In this manner, the transported object can be transported at the target speed even if there is a slip or a roll circumference error between the transport roll and the transported object. In addition, even when the measurement environment is poor due to radiant heat or steam as in online heat treatment,
Reliable speed control of the conveyed object becomes possible.

According to a second aspect of the present invention, there is provided a tracking method for a transport device having a plurality of pairs of rolls contacting both upper and lower surfaces of the transported object. A transport device for detecting the timing of passing through each roll pair, 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 transported object. Tracking method.

In general, 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 is shifted due to a change in the roll circumference due to roll slip, abrasion, or the like. There is. 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
This 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 facing the transport roll 9, and the pair of rolls (hereinafter, referred to as “roll pair”) 1 and 2 are arranged to contact both upper and lower surfaces of the transported object 9. Are located in

FIG. 1A shows a state in which the conveyed article 9 has arrived at the first pair of rolls 1 and 2. A curve 8 in the drawing 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 0 until the leading end of the conveyed article 9 reaches the pair of rolls 1 and 2, but rises rapidly upon arrival. Thereafter, the roll pairs 1 and 2 sandwich the transported object 9 and a torque current corresponding to the driving torque flows.

FIG. 1B shows a state in which the conveyed article 9 arrives at the next pair of rolls 1 and 2. First roll pair 1, 2 (Fig. 1
As in a), a sharp rise in the torque current of the drive motor (curve 8) is seen. In this way,
As shown in FIGS. 1C and 1D, the rise of the torque current is sequentially detected for each roll pair (i−1, i).

The detection time of the rise of the torque current is
t_i, Its time interval (t_i-t_i-1) To Δt _iAnd i-th
Is set to ΔL_iToss
You. Roll pair from the previous roll pair (i-1)
The transport speed V of the transported object up to the (i-th)_iIs represented by the following equation:
Is done. 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, i
N (where n <i) transport speeds V to the roll pair
The moving average of _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.

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) or the tip of the transported material is taking overall average to exit the last roll _{pair, V N = Σ i V i} / a (N-1) (4) Vave Used as In this case, the speed correction may be turned off.

As shown in FIG. 2, the speed control uses a deviation ΔV between the measured average speed Vave and the speed set value Vref.
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.

The basic loop of the speed control is the speed set value Vref
The difference between the actual speed and the actual speed Vfb is input to an ASR (speed control circuit) to perform feedback control. In the present invention, however, as described above, the error ΔVcomp such as the delay due to the actual slippage of the conveyed object is used. The speed control value Vref is corrected to control the speed. Therefore, the transport speed can be more accurately brought close to the speed set value Vref.

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.

Tracking of the position of the leading end of the steel sheet is performed by integrating the pulses of the drive motor of the roll 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, this is performed by pulse integration from the timing when the tail end is detected by the tracking sensor immediately before entering the facility.

The drive motor used for the calculation may be any one of the rolls provided that 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. After that, the rear end of the steel plate is first (entrance)
After passing through the roll, the pulse from the drive motor of the last (exit) 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, for example, every time the tip is detected by the torque current.

Equations are used for calculating the pulse rate.
The explanation is as follows. The rise of torque current
Number of pulses between roll pairs counted by
To p _iAnd the setting of the i-th role pair and the preceding roll pair
ΔL_iAnd The previous roll pair (i-1
Pulse rate R from eye) to its roll pair (i-th)
_iIs represented by the following equation. R_i= ΔL_i/ P_i (5)

Next, an average speed (moving average) is determined 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.

After the leading end of the conveyed object has passed through the final pair of rolls (N-th), the average pulse rate Rave is as follows. Rave = Rave (N, n) (7) Alternatively, take the entire average until the leading end of the conveyed object passes through the final roll pair, and calculate R _N = _{N i} R _i / (N−1) (8) as Rave Used as

[0038]

According to 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. The conveyed object can be conveyed at the target speed even if there is a slip or a roll circumference error. Further, even when the measurement environment is poor due to radiant heat or steam as in the case of online heat treatment, it is possible to control the speed of the conveyed material reliably.

In particular, in the on-line accelerated cooling device, the draining roll is evacuated as a countermeasure against the warpage of the rear end portion of the steel sheet. The present invention controls the timing accurately. Therefore, it is possible to hold the position of the draining roll until just before the rear end of the steel sheet comes off, and the cooling of the steel sheet is made uniform.

As a result, the accuracy of the cooling time and cooling stop temperature in the on-line heat treatment equipment can be improved, and the yield can be improved, material defects can be reduced, and high-grade 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]

 1 Draining roll 2 Transport roll 8 Torque current 9 Conveyed object

Claims (2)

[Claims] 1. A speed control method for a transport device having a plurality of pairs of rolls that contact upper and lower surfaces of a transported object, wherein a rise of the torque current is detected for a torque current of a drive motor of at least one of the upper and lower rolls. A speed control method for a transport device, comprising calculating a transport speed of a transported article from a relationship between the detection time and the roll installation interval, and correcting the speed set value according to a deviation from the roll speed set value. . 2. A tracking method for a transport device having a plurality of pairs of rolls contacting both upper and lower surfaces of a transported object, wherein the transported object causes each of the roll pairs to start at least when a torque current of a drive motor of one of the upper and lower rolls rises. A tracking method for a transport device, comprising detecting a timing of passing, calculating a pulse rate using the number of pulses from a drive motor and a roll interval between these timings, and calculating a position of a transported object.