JPH0745694B2 - Steel pipe transport controller - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

TECHNICAL FIELD The present invention relates to an improvement of a steel pipe transportation control device used when a steel pipe is placed on a transportation line to be transported and passed through an induction heating coil.

[Prior art]

Conventionally, in the case of induction heating a steel pipe, generally, a squeeze roll type transfer control is performed. In this control, as shown in FIG. 3, first, two movable pipe end detection carriages 1A, 1B are installed on the inlet side and the outlet side of the heating coil 3. The pipe end detection carts 1A and 1B are provided with touch rolls 4A and 4B. The touch rolls 4A and 4B are pressed and brought into contact with the pipe ends 2A and 2B of the steel pipe 2.
The pipe end detection carriages 1A and 1B are driven by a torque motor or automatic control, and are synchronized with the steel pipe transport speed. By detecting this synchronizing speed with a carriage speed detector (not shown) attached to the pipe end detection carriages 1A and 1B, the steel pipe conveying speed is indirectly detected. The steel pipe 2 is conveyed from right to left in the figure, but in the first half, the rotation speed of the skew roll 5 (DC motor 6 is adjusted so that the steel pipe conveying speed detected by the signal from the rear end detection carriage 1A matches the set value. The rotation speed of is controlled by feedback control. In the latter half, the transfer control is performed after the rear end 2A is hidden by the induction heating coil 3 by automatically switching to the signal of the front end detection carriage 1B. As described above, in the skew-roll type transfer control device, the steel roll transfer speed is detected by sequentially contacting the touch rolls 4A and 4B with the rear end 2A and the front end 2B of the steel pipe 2, and the entire length of the transfer line is detected. Feed-back control of transport speed. In FIG. 3, reference numeral 7 is a cooling water header, 8 is a cover for preventing scattering of cooling water, and 9 is an arithmetic unit.

[Problems to be Solved by the Invention]

However, the conventional control method as described above has the following problems, particularly in the case of a large-diameter and long steel pipe, when the temperature increase by induction heating and the water cooling are performed together. The first problem is that the absolute position of the pipe ends 2A and 2B of the steel pipe on the transfer line cannot be detected when it is necessary. In the induction heating of the steel pipe 2, it is generally difficult to control the heating of the pipe end, and most of the causes of the yield decrease due to the poor heat treatment are defective heat treatment of the pipe end. Therefore, conventionally, some special controls such as heating start position control, end position control, heating power pattern control, and further pipe end velocity pattern control are performed at the pipe end in order to improve the yield at the pipe end. Have been attempted. Therefore, highly accurate tracking of the absolute positions of the pipe ends 2A and 2B of the steel pipe 2 on the conveying line is an essential condition for improving the precision of these controls. However, the conventional pipe end detection cannot know the absolute position of the required pipe end at the required time. That is, when the trailing edge detection carriage 1A is functioning in the first half of conveyance, the position of the tip 2B that is most desired cannot be detected, and when the leading edge detection carriage 1B is functioning in the latter half of conveyance, the most desired rear The position of the end 2A cannot be detected. The second problem is that it is difficult for the tip detection carriage 1B to detect the steel pipe itself. For example, in the case of quenching, the heating coil is heated up to about 900 ° C to 1000 ° C and then immediately quenched with a large amount of cooling water.
A cover 8 for preventing splashing of cooling water is installed on the outlet side of 3B, but the inside of this cover 8 is in an extremely bad environment due to the cooling water and the generated steam, and the tip 2B of the steel pipe 2 is detected. It is difficult to install a precise detector in terms of maintainability and reliability of the equipment used. The third problem is that when the touch roll type is used as a device for detecting the pipe ends 2A and 2B of the steel pipe 2, there are many mechanical restrictions,
That is, the controllability is poor. That is, in the case of the touch roll type, due to mechanical contact, the end surface unevenness of the steel pipe 2 and the steel pipe 2
There is a problem that the touch rolls 4A and 4B do not rotate smoothly due to vertical movement vibration of the. In addition, in the touch roll type,
Detection cannot be done when the touch rolls 4A, 4B are separated from the pipe ends 2A, 2B, so it is necessary to keep them in contact with the pipe ends 2A, 2B at all times, but if they come too close to the steel pipe 2, they will collide and damage the detector. I have something to do.

[Object of the Invention]

The present invention has been made in view of such a conventional problem, and is capable of accurately tracking the absolute position of the pipe end, and moreover, of a steel pipe capable of maintaining high accuracy of speed control of the steel pipe. An object of the present invention is to provide a transfer control device.

[Means for solving problems]

The present invention relates to a steel pipe transportation control device which is used when a steel pipe is placed on a transportation line to be transported and is passed through an induction heating coil, and the steel pipe is moved along a transportation line in a target speed pattern to be transported. With the movable pipe end detection means for detecting relative position deviation in the conveying direction with the rear end of the steel pipe in a non-contact manner, and provided at least on the inlet side of the induction heating coil, the passage of the front and rear ends of the steel pipe. Fixed pipe end detection means for detecting, drive means for conveying the steel pipe, and feed back control of the drive means based on the relative position deviation detected by the movable pipe end detection means, and the fixed pipe end detection The above object is achieved by the provision of control means for performing tracking control based on the passage of the front and rear ends detected by the means.

[Action]

In the present invention, the movable pipe end detecting means is provided for detecting the relative position deviation in the conveying direction with respect to the rear end of the steel pipe in a "non-contact" manner. As a result, various disadvantages possessed by the mechanically contacting type touch-end type pipe end detection device, for example, the touch roll does not rotate smoothly due to end surface irregularity of the steel pipe or vertical vibration, and separation from the steel pipe. By doing so, it has become possible to eliminate the drawback that the position cannot be detected and the detector collides with the steel pipe and damages the detector. Further, since it is "non-contact", it is possible to allow the relative position of the steel pipe and the pipe end detecting means in the conveying direction to shift. As a result, the pipe end detecting means itself can be moved in a target velocity pattern for the steel pipe to be conveyed, and feedback control can be performed so as to eliminate the relative positional deviation between the pipe end detecting means and the steel pipe. . This is significant in the following points. That is, conventionally, the pipe end detection means necessarily moves the steel pipe at the same speed because it is necessary to contact the end portion of the steel pipe. Therefore, the detectable element is just the "speed" of the steel pipe, and the feed back control is fed back so that the detected speed of the steel pipe becomes the reference speed. However, the method of performing feed back control by detecting the speed of the steel pipe has been limited to maintaining accuracy of about ± 3% in the related art in combination with the fact that the detection accuracy of the touch roll type is not so high. However, when the pipe end detection means itself is moved along the conveying line in the target velocity pattern to be conveyed in this way, and the feed back control of the velocity of the steel pipe is performed so as to match this movement, that is, during conveyance, The "difference" with the coordinates at which the steel pipe should exist at the time point is detected, and the feedback control is performed based on this "difference". Therefore, the accuracy of the conveying speed is mostly determined by the running error (about ± It will be possible to keep it high in the range of 0.5%). According to the present invention, there is further provided a fixed pipe end detection means provided at least on the inlet side of the induction heating furnace and capable of detecting passage of the front and rear ends of the steel pipe. As a result, the moment when the steel pipe reaches the induction heating furnace (absolute position of the tip of the steel pipe) can be detected, and the steel pipe exists at that time in the induction heating furnace based on accurate passage information. The transport speed can be controlled so that it is located at the power coordinates. As a result, not only can the accuracy of the transfer speed be improved, but the absolute position of the pipe end can be accurately tracked, and advanced control including special control of the pipe end in the induction heating furnace can be performed accurately. Will be able to. Further, according to the present invention, since the tracking of the absolute position of the pipe end can be accurately performed in this way, it is possible to adopt a configuration in which a detector is not placed on the outlet side of the induction heating coil, which reduces maintenance and reliability. It can also be improved.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an outline of a steel pipe transportation control device before and after an induction heating coil to which an embodiment of the present invention is applied. In this embodiment, the steel pipe 2 is placed on the transport line X and transported, and in the steel pipe transport control device used when passing the induction heating coils 3A and 3B, the target speed pattern to which the steel pipe 2 should be transported. And a movable pipe detecting device 10 that moves along the transport line X and detects the relative position deviation ΔX in the transport direction with respect to the rear end 2A of the steel pipe 2, and the inlet side and the outlet side of the induction heating coil 3A. And a total of three fixed pipe end detection devices 20A to 20C provided on the outlet side of the induction heating coil 3B and for detecting passage of the pipe ends 2A and 2B of the steel pipe 2,
Squeeze roll transport facility for transporting steel pipe 2 30
And the movable roll end detection device 10
A feedback control is performed on the basis of the relative position deviation .DELTA.X detected by the control system 40, and a tracking system is controlled on the basis of the passage of the front and rear ends detected by the fixed pipe end detection devices 20A to 20C.
With. The movable pipe end detection device 10 includes a movable carriage 11 and this movable carriage.
It is mainly configured by an image sensor 12 provided on 11 and a back light 13 for the image sensor. Movable trolley
11 travels on a rail 14 provided along the transport line X on the entrance side of the induction heating coil 3A. This traveling is performed by setting the drive motor 15 on the fixed side and moving the movable carriage 11 forward and backward on the rail 14 via a speed reducer and a chain (not shown). The image sensor 12 and the backlight 13 for detecting the rear end 2A of the steel pipe 2 are mounted on the movable carriage 11. The detection range of the image sensor 12 is 200 mm, and the detection accuracy is 0.2 mm. Image sensor 12 is back light 1
Focus on tube end on side 3. Further, in order to reduce the influence of the tube end on the image sensor 12 side, a viewing direction angle θc of about 7 ° is provided on the advancing direction side. When the image sensor 12 reaches the rear end 2A of the steel pipe 2, the total light entering state of the backlight 13 becomes a partial light blocking state, and the output signal changes. The relative position deviation is obtained by averaging the signals of the image sensor 12, then 0 V at the center of the image sensor, +10 V for all light advancing on the leading side,
It can be grasped as an analog signal of ± 10V, where the total light blocking on the sending side is -10V. In this movable pipe end detection device 10,
The carriage speed control unit 1 for controlling the speed of the movable carriage 11 itself.
6, and a pulse oscillator PLG ₁ is attached for detecting the movement amount. The fixed tube end detection devices 20A to 20C are configured by photoelectric tubes that detect the front and rear ends of the steel tube 2 by transmitting and blocking light. The phototube 20A is connected to the entrance side of the induction heating coil 3A, and the phototube 20B
Is provided between the induction heating coils 3A and 3B, and the photoelectric tube 20C is provided on the exit side of the induction heating coil 3B, and the passage (absolute position) of the tube ends 2A and 2B of the steel pipe 2 at each position is detected. To do. Squeeze roll transport facility 30 for transporting the steel pipe 2
Is the same as the conventional one. That is, the skew roll conveying equipment 30 is provided with ₁₂ pairs of skew rolls 31 _{1 to} 31 ₁₂ in total, which is a set of two rolls in the illustrated example. Each of the skew rolls 31 _{1 to} 31 ₁₂ has a skew angle θ ₁ with respect to the transport direction, is mechanically connected by a rotary shaft, and is driven by one DC motor 32. The skew roll conveying equipment 30 includes a skew roll speed controller 33 for varying the rotation speed of the DC motor 32.
And a pulse oscillator PLG ₂ that detects the skew rotation speed
Is attached. The control system 40 includes an arithmetic unit 41 that performs feedback control of the rotation speed of the DC motor 32 for skew roll and tracking control of the pipe end. A cooling water header 50 is provided on the outlet side of the induction heating coil 3B, and a cooling water scattering prevention cover 61 is further provided. Since the environment inside the cooling water cover 61 is extremely bad, no complicated detector or the like is provided. In the apparatus of the present embodiment, specifically, the pipe end (rear end) position synchronization control at the start of conveyance, the speed control of the movable carriage 11 during heat treatment, the uniform speed feedback control for the movable carriage 11 at the rear end of the steel pipe, The skew roll speed control is performed in the region where the pipe end (rear end) cannot be detected. Next, specific control in this apparatus will be described with reference to FIG. FIG. 2 (A) shows the start of conveyance. The movable carriage 11 is initially at the standby position P ₁ so as not to hinder the loading of the steel pipe, and is advanced at a high speed at the same time as the start. At the same time, a ski roll transport facility 30
The squeeze roll 31 is rotated to move the steel pipe 2 forward. When the movable carriage 11 comes to the side of the steel pipe 2, the total incoming light state of the backlight 13 becomes a partial light blocking state, and the output signal is from + 10V to 0V.
Change to the side. This state is judged by the calculation unit 41, and this position
The speed of the movable carriage 11 is switched from P ₂ to high speed feedback control in which the target speed (constant speed or pattern running) predetermined according to the heat treatment condition is the command speed from P ₂ . Further, the rotation speed control of the skiw roll conveyance facility 30 is switched to the uniform speed feedback control with the movable carriage 11. This uniform speed control causes the movable carriage 11 to travel at the target speed,
The number of rotations of the skew roll 31 (the number of rotations of the DC motor 32) is increased or decreased so that the relative position deviation with respect to the movable carriage 11 becomes zero, so that the transport speed of the steel pipe 2 matches the straight traveling speed of the movable carriage 11. . For example, when the heat treatment speed to be obtained is a constant speed, the movable carriage 11 unconditionally travels on the rail 14 with high accuracy of about ± 0.5%. While the steel pipe 2 is being skew-conveyed at the same speed, the deviation amount becomes the standard value, and the skew-roll conveying facility 30
The DC motor 32 that drives the motor also rotates at a constant speed. However, in actuality, the steel pipe 2 is transported while rotating in a large slipping manner due to twisting of the steel pipe 2, convex portions of the welding bead, uneven installation of the skew rolls, uneven wear of the rolls, and the like. Therefore, even if the DC motor 32 rotates at a constant speed, it is not always conveyed at a constant speed. However, if the steel pipe 2 becomes slower than the movable carriage 11, for example,
The deviation is detected by the image sensor 12 above 11. As a result, the feed back control is performed so that the rotation speed of the DC motor 32 for driving the skew roll is increased and the steel pipe speed is increased, and the deviation amount is returned to the reference value. This control is different from the feed back control that detects the transport speed of the steel pipe, and the speed control accuracy of the movable carriage 11 ± 0.
It is possible to realize the control of the heat treatment rate as high as 5%. In this way, when the steel pipe 2 is conveyed while performing the uniform speed control, the tip 2B of the steel pipe 2 eventually approaches the inlet side of the induction heating coil 3A, and at this moment, the fixed pipe end detection device (photoelectric tube)
Detected by 20A. Therefore, the absolute position of the tip 2B after passing through the photoelectric tube 2A can be obtained by integrating the straight moving amount of the steel tube 2 obtained from the speed detection pulse signal of the movable carriage 11 and the relative position deviation signal. Therefore,
It is also possible to perform highly precise special heat treatment control at the tip. This tracking is performed by the fixed pipe end detection device 20.
Since the error is corrected when the tip 2B passes through B and 20C, it can be maintained with higher accuracy. In FIGS. 2 (A) and 2 (B), the area between P ₂ → P ₃ → P _{4 corresponds} to the alignment speed control area based on the relative position error with respect to the movable carriage 11. As shown in FIG. 2B, the rear end of the steel pipe 2
When 2A reaches P ₄ near the inlet of the induction heating coil 3A, the movable carriage 11 cannot detect the rear end 2A.
Therefore, the uniform speed control is ended at this position P ₄ , and automatic switching is performed to control the rotation speed of the ski roll. The skew roll speed control here is, for example, in the case of heat treatment at a constant speed,
Memorizes the skew roll speed just before the movable carriage is separated,
A method of holding this rotation speed is adopted. Until P _{5 in} FIG. 2 (C), that is, until the steel pipe 2 leaves the cooling water header 50, the steel pipe 2 is conveyed by the skew roll speed control, which does not depend on the uniform speed control, and heat treatment is performed. Therefore, although the accuracy of transportation is somewhat lowered, since it is a short period with respect to the entire length, the transfer of the steel pipe 2 to the skew roll is small, and the variation in the transportation speed does not pose a practical problem. or,
During this period, the tracking error is canceled particularly by the detection of the rear end 2A of the steel pipe 2 by the fixed pipe end detection devices 20A to 20C, so that the speed control error can be reduced to a less problematic region. It's ready. In the above embodiment, three fixed tube end detecting devices were provided, but as described above, the most important fixed tube end detecting device in the present invention is provided on the inlet side of the induction heating coil. Therefore, this may be omitted for other fixed tube end detecting devices.

【The invention's effect】

As described above, according to the present invention, the speed control speed of the steel pipe can be improved from about ± 3% to about ± 0.5%, and the tracking accuracy (absolute position detection accuracy) of the pipe end position is ± 50 mm. It has become possible to improve from to ± 1 mm. As a result, the accuracy of heating control of the entire steel pipe is improved, and even at the end of the pipe where heat treatment defects are likely to occur, heating control can be performed at the target temperature, and quality, yield, and maintainability can be improved. It became like this.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an overall configuration of an embodiment of a steel pipe transportation control device according to the present invention, FIG. 2 is a schematic plan view showing how a steel pipe is transported, and FIG. 2 is a schematic block diagram corresponding to FIG. 1, showing the entire transport control device for the steel pipe of FIG. 2 ... Steel pipe, 2A ... Rear end, 2B ... Tip, 3A, 3B ... Induction heating coil, 10 ... Movable pipe end detection device, 11 ... Movable carriage, 12 ... Image sensor, 13 ... Backlight , 20A to 20C ... fixed tube end detector (phototube), 30 ... skew roll transfer equipment, 40 ... control system, 41 ... computing section.

Claims (1)

[Claims] 1. A steel pipe transportation control device used when a steel pipe is placed on a transportation line to be transported and passes through an induction heating coil, wherein the steel pipe is accompanied by a target speed pattern to be transported along the transportation line. A movable pipe end detection means for detecting a relative position deviation in the transport direction with the rear end of the steel pipe in a non-contact manner while moving, and a passage provided at least on the inlet side of the induction heating coil for passing the front and rear ends of the steel pipe A fixed pipe end detecting means for detecting the steel pipe, a driving means for conveying the steel pipe, and a feedback control of the driving means on the basis of the relative position deviation detected by the movable pipe end detecting means. A transport control device for a steel pipe, comprising: control means for performing tracking control based on passage of the front and rear ends detected by the detection means.