JP7505652B2 - Crop shear cutting control system - Google Patents

Description

The present disclosure relates to a crop shear cutting control system.

Crop shears are installed, for example, in hot rolling lines in steel plants, and are used to crop out defective parts at the leading or trailing ends of the material (steel) being cut while it is being transported. Crop shears are driven by a drive device such as an electric motor, and are configured to cut the material with upper and lower cutting blades via a transmission. To improve the yield of the material being cut, it is necessary for the crop shear to cut the material with high precision at the desired set position.

A shape measuring device is installed at the exit of the roughing mill in the hot rolling line, and the shape of the leading or trailing end of the material to be cut is measured. The cutting position of the material to be cut is set from the measured shape. The movement amount of the material to be cut is calculated using a programmable logic controller (hereinafter referred to as "PLC") and a speed detector such as a resolver attached to the conveying table, and the speed detected by a measuring roll attached to the exit of the crop shear, and tracking control is performed from this movement amount by the PLC to calculate the drive timing of the crop shear so that the material is cut at the set cutting position.

For example, when controlling a crop shear using the control device disclosed in Patent Document 1 below, the timing to start the crop shear is calculated after the workpiece detector detects the workpiece. In this calculation, the acceleration rates of the crop shear and the workpiece are assumed to be constant, and the start timing of the crop shear is calculated based on the speed of the workpiece at the time of detection and the current position of the workpiece. The method for calculating the start timing of the crop shear is described below.

First, the distance L _CUT for generating the start timing of the crop shear is expressed by the following formula (1): In the following formula (1), L _MS is the distance from the workpiece detector to the center of the crop shear (absolute distance on the equipment = constant value), L _SET is the cutting length of the workpiece (set value), and L _S is the distance that the workpiece travels from when the crop shear is started until cutting is performed.
[Formula 1]
L _CUT = L _MS - L _SET - L _S ... (1)

In the above formula (1), L _MS and L _SET are fixed values. Therefore, if L _S does not include an error, the workpiece can be cut exactly at the set cutting position. However, L _S includes a function of speed as shown in the following formula (2). In the following formula (2), L _c is the distance (constant) that the crop shear rotates from when it starts to when it cuts, V is the movement amount (set value) of the workpiece, K is the lead rate (set value), and α is the acceleration (constant) of the crop shear. V corresponds to the material speed. If the material speed V is constant, the error of L _s is small, but if the material speed V fluctuates, the error of L _s becomes large.
[Formula 2]

In order to correct the fluctuation of the material speed V, there is a cutting point tracking control that compares the crop shear peripheral speed and the material speed after the crop shear is started, and performs speed correction based on the crop shear speed standard. The time _ts from when the crop shear is started until the cutting blade starts cutting is expressed by the following formula (3). In the following formula (3), _ls is the distance (arc length) to the bottom dead center of the crop shear cutting blade, _ΔLs is the distance (arc length) from the crop shear cutting start point to the bottom dead center, and _Vb is the crop shear cutting speed. The crop shear cutting speed _Vb corresponds to the speed standard described later.
[Formula 3]
_ts = ( _ls - _ΔLs ) / _Vb = ( _ls - _ΔLs ) / K · V ... (3)

On the other hand, the time _tb required for the cut point of the material to reach the cut start point at the same time is expressed as the following formula (4): In the following formula (4), _lb is the distance until the cut point of the material to be cut reaches the bottom dead point, and _lc is the distance from the cut start point of the material to the bottom dead point.
[Formula 4]
t _b =( l _b - _{l c} ) / V (4)

_Ib is expressed as in the following formula (5): In the following formula (5), L _CUT is the distance from the start of cut tracking to the cut start position, and L _TRK is the distance to the cut point position after the crop shear is started.
[Formula 5]
l _b = L _MS - L _CUT - L _TRK (5)

It is only necessary to perform control so that the above formula (3) and the above formula (4) are equal, that is, so that t _s =t _b , thereby obtaining the following formula (6).
[Formula 6]
(l _s -ΔL _s )/K-(l _b -l _c )=0 (6)

From the above equation (6), the cutting blade speed can be controlled so that the amount of cutting blade movement always maintains a constant relationship with the amount of material movement.

The amount of correction v of the cutting blade speed by the above control is expressed by the following formula (7): In the following formula (7), k _s is a position control gain (=Δc/3).
[Formula 7]
v = k _s {(l _s - ΔL _s )/K - (l _b -l _c )}
= k _s {( l _s - ΔL _s ) / K - ( L _MS - L _CUT - L _TRK - l _c ) } ... (7)

Furthermore, the following Patent Document 2 discloses a method for improving the cutting accuracy at a set cutting point by measuring the cutting length L _SET of the workpiece with a shape detector in order to improve the yield.

Japanese Patent Publication No. 2012-66313 Japanese Patent Publication No. 2012-170997

However, even when speed detectors such as resolvers and measuring rolls are used, the speed of the workpiece fluctuates in reality, which results in errors in tracking using each speed detector, causing errors in the cutting accuracy at the set cutting point. Such speed fluctuations are caused by fluctuations in the reduction rate of the finishing rolling mill, unevenness (non-flatness) of the surface of the workpiece, and slippage of the workpiece on the speed detector. Furthermore, since there is no mechanism for detecting and correcting the actual position of the workpiece after cutting tracking begins, tracking control must be performed using the speed of the workpiece detected by each speed detector.

The present disclosure has been made to solve the problems described above, and aims to provide a cutting control system for a crop shear that is capable of minimizing cutting errors of the workpiece at a set cutting point, even if speed fluctuations occur in the workpiece.

The first aspect relates to a cutting control system for a crop shear that cuts the material being cut while it is being transported along a hot rolling line. The cutting control system is disposed on the entry side of the crop shear and is equipped with an image detector that detects an image of the material being cut while it is being transported. The leading or trailing end position and amount of movement of the material being cut are obtained from image data detected by the image detector, and the drive speed of the cutting blade of the crop shear is corrected based on the obtained leading or trailing end position and amount of movement of the material being cut.

The second aspect has the following features in addition to those of the first aspect. The cutting control system further includes a speed detector that detects the speed of the material to be cut. A speed reference for the cutting blade is calculated from the speed detected by the speed detector, and the speed reference is corrected using the leading or trailing end position and the amount of movement of the material to be cut.

The third aspect has the following features in addition to the first or second aspect: After starting the crop shear, the cutting control system is configured to compare the movement amount with the arc length movement amount of the crop shear to perform correction.

The fourth aspect has the following features in addition to the second aspect: The cutting control system is configured to perform correction taking into account a transmission delay of image data from the image detector.

According to the present disclosure, the drive speed of the cutting blade of the crop shear is corrected based on the position and movement amount of the workpiece determined from the image data of the workpiece detected by the image detector, rather than the speed of the workpiece detected by each speed detector. This makes it possible to minimize cutting errors of the workpiece at the set cutting point, even if the speed of the workpiece fluctuates.

FIG. 1 is a diagram for explaining a configuration of a hot rolling line equipped with a cutting control system for a crop shear according to an embodiment. FIG. 1 is a diagram illustrating an example of a configuration of an image identification device. FIG. 2 is a diagram illustrating an example of a hardware configuration of a cutting control device. 13 is a diagram for explaining correction of a cutting blade speed of a crop shear. FIG.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that elements common to each drawing will be given the same reference numerals and duplicate explanations will be omitted.

Figure 1 is a diagram illustrating the configuration of a hot rolling line equipped with a crop shear cutting control system according to an embodiment.

The hot rolling line L is equipped with a roughing mill 1 and a finishing mill 2. In the following description, the roughing mill 1 is the upstream side, and the finishing mill 2 is the downstream side. Between the roughing mill 1 and the finishing mill 2, a conveying table 3 is installed, which conveys the steel material (rolled material) to be cut M and is equipped with a speed detector such as a resolver (not shown). The hot rolling line L is further equipped with a crop shear 4 capable of cropping the leading or trailing end of the material M to be cut while being conveyed and traveling on the conveying table 3. The crop shear 4 is driven by a crop shear drive device 40. In this embodiment, the case of cutting the leading end of the material M to be cut will be described as an example.

A shape detector 5 capable of measuring the shape of the material M to be cut is installed at the exit side of the roughing mill 1. A steel end detector 6 is installed downstream of the shape detector 5 as a material to be cut detector capable of detecting the passage of the leading end of the material M to be cut. A measuring roll 7 capable of detecting the tail end speed of the material M to be cut is installed downstream of the crop shear 4 and at the entry side of the finishing mill 2.

The hot rolling line L is provided with a cutting control system according to this embodiment. The cutting control system has an image detector 8 that detects an image of the workpiece M, an image identification device 80, and a cutting control device 10.

The image detector 8 is, for example, a CCD camera that is set downstream of the steel material end detector 6 and at the inlet side of the crop shear 4. The image detector 8 is connected to an image identification device 80.

Figure 2 is a diagram showing an example of the configuration of the image recognition device 80. The image recognition device 80 includes an image input unit 81, an equipment length input unit 82, a pixel-to-length conversion unit 83, a material position detection unit 84, and a material speed detection unit 85.

The image input unit 81 takes in image data (image information) from the image detector 8 in real time and outputs it to the material position detection unit 84. The equipment length input unit 82 takes in length information of a preset image area and outputs it to the pixel-to-length conversion unit 83. The pixel-to-length conversion unit 83 derives the length per pixel of the image and outputs it to the material position detection unit 84. The material position detection unit 84 detects the tip of the workpiece M from the image data input from the image input unit 81, and outputs the detected tip of the workpiece M to the cutting point tracking control unit 17 and the material speed detection unit 85 as tracking information. The material speed detection unit 85 calculates the movement amount of the workpiece M from the tip of the workpiece M and the length per pixel of the image. That is, the actual movement amount (speed) of the workpiece M is obtained from the frame rate (number of frames per second) of the image data and the movement amount per frame of the end position of the workpiece M. The material speed detection unit 85 outputs the calculated movement amount of the workpiece M to the cutting point tracking control unit 17 described later as tracking information.

The cutting control device 10 comprises a cut point setting unit 11, a leading edge speed detection unit 12, a tail edge speed detection unit 13, a crop shear calculation timing generation unit 14, a crop shear start calculation unit 15, a crop shear drive control unit 16, and a cut point tracking control unit 17.

The cutting point setting unit 11 sets the cutting point (cutting position) from the shape of the workpiece M measured by the shape detector 5. The leading edge speed detection unit 12 is connected to the conveying table 3 and detects the leading edge speed of the workpiece M. The tail edge speed detection unit 13 is connected to the measuring roll 7 and detects the tail edge speed of the workpiece M. The crop shear calculation timing generation unit 14 receives the detection of the leading edge (or tail edge) of the workpiece M by the steel end detector 6 as input and generates the calculation timing of the crop shear 4. When the crop shear calculation timing is input, the crop shear start calculation unit 15 calculates the start timing of the crop shear 4 from the cutting point of the workpiece M and the leading edge speed and tail edge speed of the workpiece M. When the start timing, which is the calculation result, is reached, the crop shear drive control unit 16 calculates a speed reference according to the leading edge speed or tail edge speed of the workpiece M. The cutting point tracking control unit 17 calculates a speed correction amount for the crop shear 4 from the position information of the workpiece M input from the image identification device 80, i.e., the end and movement amount of the workpiece M, and outputs the calculated speed correction amount to the crop shear drive control unit 16. The crop shear drive control unit 16 adds the speed correction amount input from the cutting point tracking control unit 17 to the calculated speed reference, and drives the crop shear drive device 40.

Here, since the image data is digital data, a transmission delay occurs, but since it is a periodic process, the speed error from the delay time can be obtained. The break point tracking control unit 17 can add this speed error to the speed correction amount.

There is no limitation on the specific structure of the cutting control device 10, but an example may be as follows. Figure 3 is a diagram showing an example of the hardware configuration of the cutting control device 10. The functions of the cutting control device 10 can be realized by the processing circuit shown in Figure 3. Similarly, the functions of the image identification device 80 can be realized by the processing circuit shown in Figure 3. This processing circuit may be dedicated hardware 10a. This processing circuit may include a processor 10b and a memory 10c. This processing circuit may be partially formed as dedicated hardware 10a, and further include a processor 10b and a memory 10c. In the example of Figure 3, a part of the processing circuit is formed as dedicated hardware 10a, and the processing circuit also includes a processor 10b and a memory 10c.

At least a part of the processing circuit may be at least one dedicated hardware 10a. In this case, the processing circuit may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. The processing circuit may include at least one processor 10b and at least one memory 10c. In this case, each function of the cutting control device 10 is realized by software, firmware, or a combination of software and firmware. The software and firmware are written as a program and stored in the memory 10c. The processor 10b realizes the functions of each part by reading and executing the program stored in the memory 10c. The processor 10b is also called a CPU (Central Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, or a DSP. The memory 10c may be, 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 manner, the processing circuitry can realize each function of the cutting control device 10 by hardware, software, firmware, or a combination thereof.

Figure 4 is a schematic diagram for explaining the correction of the cutting blade speed of the crop shear 4. In Figure 4, crop shears 4a, 4b, and 4c with different postures are shown. 4a shows the crop shear at the starting point P1, 4b shows the crop shear at the cutting start point P2, and 4c shows the crop shear at the bottom dead center P3.

As shown in FIG. 4, if the length (set value) of the tip portion (hatched portion) of the workpiece M to be cut is _LSET , the material speed is V, and the distance from the steel end detector 6 to the center of the crop shear 4 (absolute distance on the equipment = constant value) is _LMS , then the distance _LCUT that generates the start timing of the crop shear 4 is expressed by the following equation (8).
[Formula 8]
L _CUT = L _MS - L _SET - L _s ... (8)

Here, in the above formula (8), _{L_S} is the distance that the workpiece M travels from when the crop shear 4a is started until cutting is performed by the crop shear 4b. When the cutting point of the workpiece M arrives at position P1, a distance _{L_CUT} away from the steel end detector 6, the crop shear 4a is started. In other words, P1 is the crop shear start point. Thereafter, the distance _{L_TRK} of the cutting point of the workpiece M from the crop shear start point P1 is tracked. Tracking of _{L_TRK} is performed from the crop shear start point P1 to the cutting start point P2 of the crop shear 4b. In other words, the movement amount of the workpiece M calculated from the image data is compared with the arc length _{L_s} of the crop shear 4.

As in the above-mentioned formula (7), the correction amount v of the cutting blade speed of the crop shear 4 by the cutting point tracking control unit 17 can be obtained by the following formula (9): In the following formula (9), ΔL _S is the arc length movement amount of the crop shear 4 from the cutting start point P2 of the crop shear 4b to the bottom dead point P3 of the crop shear 4c.
[Formula 9]
v = k _s {(l _s - ΔL _s ) / K - (L _MS - L _CUT - L _TRK - l _c )} (9)

In this embodiment, the output signals of the material position detection unit 84 and the material speed detection unit 85 of the image identification device 80 are input to L _TRK in the above equation (9). Then, the correction amount v calculated in the above equation (9) is output to the crop shear drive control unit 16. As a result, even if the speed V of the workpiece M varies, the actual position of the workpiece M is tracked. This makes it possible to suppress errors in the tracking control by the cutting control device 10 as much as possible.

As described above, according to this embodiment, the position and actual speed of the workpiece M are obtained from the image data of the image detector 8 provided downstream of the steel end detector 6, and a correction amount v for the speed of the cutting blade of the crop shear 4 is obtained from the obtained position and actual speed, thereby minimizing cutting errors of the workpiece M at the set cutting point.

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. In the above embodiment, the case of cutting the tip of the material M to be cut is described as an example, but it can also be applied to the case of cutting the tail end of the material M to be cut. 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 it is specifically stated or clearly specified in principle. In addition, the structure etc. described in the above embodiment is not necessarily essential to the present invention, except when it is specifically stated or clearly specified in principle.

L...hot rolling line, M...material to be cut, 3...conveyor table (speed detector), 4...crop shear, 7...measuring roll (speed detector), 8...image detector

Claims (4)

In a cutting control system for a crop shear that cuts materials traveling on a hot rolling line,
An image detector is provided at the inlet side of the crop shear to detect an image of the workpiece during transport,
A cutting control system for a crop shear configured to determine the leading end position or tail end position and amount of movement of the material to be cut from image data detected by the image detector, and to correct the drive speed of the cutting blade of the crop shear based on the determined leading end position or tail end position and amount of movement of the material to be cut. The crop shear cutting control system of claim 1 further comprises a speed detector that detects the speed of the material to be cut, and is configured to calculate a speed reference for the cutting blade from the speed detected by the speed detector, and to correct the speed reference using the leading end position or the trailing end position and the speed of the material to be cut. The crop shear cutting control system of claim 1 or claim 2 is configured to compare the movement amount with the arc length movement amount of the crop shear and perform the correction after starting the crop shear. The crop shear cutting control system of claim 2, configured to perform the correction taking into account a transmission delay of the image data from the image detector.

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