JPH0342108A - Learning method for starting point of control for tube end in reducing mill - Google Patents

Abstract

PURPOSE:To realize stable control of tube end by correcting predetermined start timing of control for the head and tail end of tube using the timing of detected bite and tail passage and using corrected result that is learned at the next rolling. CONSTITUTION:Driving current and rotating speed of a motor 3 for a rolling roll 21 are respectively detected with a current detector 33 and a rotating speed detector 32 and rolling torque is calculated with computing element 5 for rolling torque. Timing of bite and tail passage of tube 1 is detected from a fluctuating state of rolling torque with a timing computing element 6. Predetermined timing of control start for the head and tail end of tube 1 is corrected using detected timing of bite and tail passage. Those corrected results are learned with a rolling controller 7 and is used at the next rolling. Thereby, time difference among the moment of control start for the head and tail end of tube, moment of bite and moment of tail passage can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for learning a tube end control starting point of a reducing rolling mill.

[Prior art]

When rolling a tube with a reduction rolling mill (stretch reducer), if the circumferential speed of the rolls is kept constant, the tension acting on both ends of the tube is smaller than the tension acting on the middle portion of the tube. A phenomenon occurs in which the wall thickness at both end portions becomes thicker than the middle portion.Thus, the thickened portion is cut off as a crop, causing a decrease in yield.

In order to suppress the aforementioned increase in wall thickness at both ends of a tube and improve yield, a method of controlling the circumferential speed of the rolling rolls when rolling both ends of a tube is generally used. When controlling the circumferential speed of the rolls when rolling both ends of the tube in this way, it is important that the timing for starting the control is appropriate.

As a method for determining the control start timing as described above, the following method is disclosed. The first method is to determine the control start timing based on the detection results of a tube detector that detects passage of the tube on the entry side of the reducing rolling mill and an Ilil electric shock detector of the roll drive motor that detects tube jamming. There is a method (Japanese Patent Publication No. 45-1341). The second method is to determine the control start timing by calculating the time from when the tube detector on the entrance side of the reducing rolling mill detects the tube end to when it reaches each roll stand (Unexamined Japanese Patent Publication No. Publication No. 1983-77010).

A third method is to install a tension detector in each roll stand, detect tube jamming and bottom-out from the detection results of the tension detector, and start control.
108414). A fourth method is to install a tube detector between each roll stand and determine the control start timing from the detection result of the tube detector (Japanese Patent Laid-Open No. 6
0-221108).

[Problem to be Solved by the Invention] However, in the first method described above, since the roll circumferential speed is controlled after the impact current detector detects tube jamming, the impact current detector and roll drive are There is a problem in that the control start timing is delayed due to a delay in response of the motor. In the second method, even if the rolling schedule is the same, the outer diameter and wall thickness of the tube differ from roll stand to roll stand as the rolling progresses. There is a problem in that the passage time is different, and there is a large discrepancy between the control start timing and the timing of the tube's engagement and tailing.

In the third method, the reduction rolling mill is generally composed of a large number of roll stands and requires a large number of tension detectors, resulting in high equipment costs.

In the fourth method, as described above, since there are many roll stands, a large number of tube detectors must be provided, which increases the frequency of failure of the detectors, and there is a problem that stable rolling cannot be performed.

The present invention has been made in view of the above circumstances, and includes determining rolling torque from the drive current and rotational speed of the motor that drives the rolling rolls, detecting the timing of tube jamming and tail-off from the rolling torque, and The detected timing of biting and tail-off is used to correct the predetermined pipe tip and trailing end control start times, and the correction results are learned and used for rolling the next pipe. The purpose of the present invention is to provide a method for learning the starting point of tube end control in a reducing rolling mill, which has a small time difference between the rear end control start point, the biting point, and the bottom removal point, and can perform stable tube end control. do.

[Means to solve the problem]

The tube end control starting point learning method for a reducing rolling mill according to the present invention is as follows:
In a tube end control method for a reducing mill that adjusts the rotational speed of a rolling roll during rolling of a tip and a trailing end of a tube to be rolled, the drive current and rotational speed of a motor that drives the rolling roll are detected; Calculate the rolling torque from the results, detect the biting and tail removal of the pipe from the fluctuation state of the rolling torque, and calculate the time difference and tail removal between the detected biting point and the predetermined tip control start time. Calculate the time difference between the time and a predetermined rear end control start time, determine whether each time difference is within a predetermined range, and if the time difference is not within the predetermined range, the time difference is within the predetermined range. The present invention is characterized in that the start point of the tip control and the start point of the rear end control of the tube are respectively corrected, and the correction results are learned and used for the next rolling.

[Effect]

The total generated torque of the motor is determined from the drive current of the motor, the acceleration/deceleration torque is determined from the change in rotational speed, and the rolling torque is calculated by subtracting the acceleration/deceleration torque from the total generated torque. The time when the rolling torque shows a predetermined state change for each is determined to be biting and bottoming out, and the time difference between this biting point and the start point of the leading edge control and the bottoming out point is determined by the time difference between the biting point and the start point of the trailing edge control. The start point of the leading end control and the starting point of trailing end control f111 are corrected so that the time difference from The time difference between the biting point and the bottom removal point is appropriate, and stable tube end control can be performed.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof. FIG. 1 is a block diagram showing the configuration of a reducing mill used to implement a method for learning a tube end control starting point of a reducing mill according to the present invention. 2.2... in the figure is a rolling roll stand, and the tube 1 to be rolled is conveyed by conveyor rolls (not shown) in its elongated direction, which is the direction shown by the white arrow in the figure, and each of the rolling rolls Stand 2.2...
- Reduction rolling is performed at. A photosensor is provided near the entrance side of the rolling roll stands 2, 2 on the conveyance path of the pipe l, and the operation of the photosensor causes the pipe l to
A tube end detector 8 is provided to detect the front and rear ends of the tube.

The tube end detector 8 supplies the detection result of the tube 1 to a rolling controller 7 and a timing calculator 6, which will be described later.

The rolling rolls 21 of the rolling roll stands 2, 2...
21 are driven by roll drive motors 3, 3, . . . via a speed reducer 31. The rolling roll stand 2.2 among the rolling roll stands 2.2...
...Roll drive motors 3, 3 of odd-numbered rolling roll stands 2, 2, counting from the roll stand on the entry side
... are provided with a current detector 32 for detecting the drive current of the roll drive motors 3, 3... and a rotation speed detector 33 for detecting the rotation speed. The current detector 32.
32... and rotational speed detectors 33, 33... are provided to motor drive controllers 4, 4, . . The motor drive controllers 4, 4, . . . are given drive control information for the roll drive motors 3, 3, . . . from a rolling controller 7, which will be described later.
・ is the roll drive motor 3, 3 based on the drive control information.
Controls the rotation speed of... Further, the current detector 3
2.32... and the rotational speed detectors 33, 33... are also given to the rolling torque calculators 5, 5... via the motor drive controllers 4.4...

The rolling torque calculators 5, 5, . . . calculate rolling torque based on the detection results of the current and rotational speed input from the motor drive controllers 4, 4, .
This calculation result is given to the timing calculator 6.6. The timing calculators 6, 6, . . . are supplied with the rolling torque calculation result signal, a tube end detection signal from the tube end detector 8, and a tube end control start signal from the rolling controller 7, which will be described later. Based on this, the amount of modification of the pipe end control start timing signal is calculated, and the result of this calculation is given to the rolling controller 7 as a modification signal.

The rolling controller 7 is supplied with a tube end detection signal from the tube end detector 8 and a correction signal from the timing calculator. Then, timing is started from the time when the tube end detector 8 detects the tube end, and when this timing result reaches a predetermined setting value of the tube end control start timing of each roll stand 2.2... , the tube end control start signal is sent to each motor drive controller 4,
4... and each timing calculator 6,6... Further, the set value of the tube end control start timing is modified based on a modification signal given from the tying calculators 6, 6, . . . .

Next, a method of controlling the tube end using the apparatus configured as described above will be explained. Figure 2 is a flowchart 1 showing the procedure of the tube end control method, and Figure 3 is a flowchart showing the procedure of the tube end control method.
Graphs showing a method for detecting biting, FIG. 4(a) ~
(C1 is a graph showing a method for detecting tailing of tube 1 from rolling torque. In Figures 3 and 4, time is plotted on the horizontal axis, and rolling torque is plotted on the vertical axis. The relationships are shown below.

First, in step 1, the tube end detector 8 is turned on when the tip of the tube 1 passes, and inputs a tube end detection signal to the timing calculator 6 and rolling controller 7.

Then, the timing calculator 6 and the rolling controller 7 start timing (Step 2), and the rolling torque calculator 5 starts rolling according to the following equation (1) based on the detection results of the drive current IH and rotational speed ω of the roll drive motor 3. Calculate torque TL.

However, Kφ: Field constant J: Moment of inertia of the roll drive system In the above equation (1), the total generated torque of the roll drive motor 3 is determined from the drive current ■9, and the rate of change of the rotational speed ω is calculated from the total generated torque. The rolling torque TL is obtained by subtracting the acceleration/deceleration torque obtained from the above (step 3). Note that in an actual device, performing a differential operation such as the second term of Equation 11 causes noise, so in order to prevent this, a first-order lag is added to the detection results of the drive current ■H and rotational speed ω. The rolling torque TL is determined by adding the elements.

Next, when the time measurement result of the rolling controller 7 reaches a preset tube tip control start timing set value, a tube tip control start signal is input to the timing calculator 6, and a drive control signal is input to the motor drive controller 4. is manually operated, pipe tip control is started, and the rotational speed of the roll drive motor 3 is increased. In addition, in parallel with this, the timing calculator 6 calculates the rolling torque T calculated by the rolling torque calculator 5.
Biting of the tube 1 is detected from L.

Detection of the jamming of the tube 1 is performed by determining that the point in time when the rolling torque TL exceeds a predetermined value is the jamming point, as shown in FIG. 3 (Step 4).

In step 5, the time from when the tube end detector 8 detects the tip of the tube 1 to when the tube 1 is detected to be jammed based on the rolling torque TL, and the tube tip control start timing set in advance in the rolling controller 7 are determined. The deviation from the set value is calculated, and it is determined whether the deviation is within a predetermined range (step 5). If the deviation is not within the predetermined range in step 5, the tube tip control start timing set value is corrected in step 6 so that the deviation is within the predetermined range. This revised tube tip control start timing setting value is stored in the rolling controller 7 and used when rolling the next tube. When this tube tip control is completed, the rotation speed is reduced to a predetermined value.

As the rolling state progresses, the tube end detector 8 is turned off as the rear end of the tube 1 passes, and the tube end detection signal is no longer sent manually to the timing calculator 6 and rolling controller 7 (step 7).
).

The tying calculator 6 and the rolling controller 7 start measuring time again from the time when this tube end detection signal is turned off (step 8).

Next, when the time measurement result of the rolling controller 7 reaches a preset W trailing end control start timing setting value, a pipe end control start signal is manually inputted to the timing calculator 6 and the motor drive controller 4 is A drive control signal is input, front and rear end control is started, and the rotational speed of the roll drive motor 3 is increased. In addition, in parallel with this, the rolling torque T calculated by the rolling torque calculator 5 is used in the tying calculator 6.
The end of the tube 1 is detected from L. Detection of the end of the tube I is performed as shown in FIGS. 4(a) to 4(C). (al
shows a method for detecting tailing in the roll stands 2, 2, . (C) is the roll stand 2 on the downstream side of the rolling mill;
2. In this case, the time point when the rolling torque TL becomes smaller than a predetermined value is determined to be a bottom dropout. +b>; This shows a method for detecting bottom drop in the roll stand 22 between the upstream side and the downstream side according to rolling section 111. In this case, the rolling torque TL changes from positive to negative. When the rolling torque TL changes and then the absolute value of the rolling torque TL becomes smaller than a predetermined value, it is determined that the rolling torque has reached the bottom (step 9).

In step 10, the time from when the rear end of the tube 1 is detected by the tube end detector 8 to when the tail end of the tube 1 is detected from the rolling torque TL, and the front and rear end control set in advance in the rolling controller 7 are determined. The deviation from the start timing setting value is calculated, and it is determined whether the deviation is within a predetermined range (step 10).

If the deviation is not within the predetermined range in step 10, the front/rear end control start timing set value is corrected in step 11 so that the deviation is within the predetermined range.

The method explained above is for each roll stand 2.2...
It will be carried out in 5 and 6 are graphs showing a method of correcting the tube tip control start timing set value, where the horizontal axis shows the time difference between the tube tip control start timing set value and the biting timing ((the Z axis shows the time difference between the tube tip control start timing set value and the biting timing). Indicates the roll stand number assigned from the upstream side, and each roll stand 2, 2...
- Show the time difference on your own. Fig. 5 shows a case where the start timing of tube tip control in each roll stand 2, 2, etc. is uniformly deviated from a predetermined appropriate range A, and in such a case, as indicated by the arrow in the figure, Each roll stand 2. is adjusted so that the time difference falls within the appropriate range A.
2. Uniformly correct the tube tip control start timing.

Fig. 6 shows a case where there is an error in the setting of the tube tip control start timing and the passing time between roll stands of each roll stand 2, 2, etc. In such a case, as indicated by the arrow in the figure, the above The tube tip control start timing of each roll stand 2, 2, etc. is corrected so that the time difference falls within the appropriate range A, and the results of this correction are used for rolling the next tube.

Further, the method for modifying the front and rear end control start quilling setting value is performed in the same manner as the method for modifying the tube tip control start timing as described above, and the result of this modification is used for rolling the next tube.

The tube end control method as explained above is applied to each roll stand 2,
2..., each roll stand 2゜2...
- Repeat the above method to optimize the blue light and rear end control start timing setting values.

In this embodiment, the correction of the tube end control start timing was performed at odd-numbered roll stands from the entrance side of the rolling mill, but the modification is not limited to this and may be performed at all roll stands.

[Effects] As described in detail above, the method for learning the tube end control starting point of a reducing rolling mill according to the present invention calculates the rolling torque from the drive current and rotational speed of the motor that drives the rolling rolls, and uses the rolling torque to calculate the tube end control start point learning method. Detects the timing of entry and exit, uses the detected timing of entry and exit to modify the predetermined blue light and trailing end control start timing, and learns this modification result for the next time. Blue light for use in rolling rolling agents.

The present invention has excellent effects such as a small time difference between the start of rear end control and the time of biting and tailing, and stable tube end control can be realized.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a reducing mill used to implement the tube end control starting point learning method for a reducing mill according to the present invention, FIG. 2 is a flowchart showing the procedure of the tube end control method, and FIG. The figure is a graph showing a method for detecting tube jamming based on rolling torque, Figure 4 is a graph showing a method for detecting tube tailing from rolling torque, and Figures 5 and 6 are tube tip control start timing settings. It is a graph showing a method of correcting values.

Claims (1)

[Scope of Claims] 1. A tube end control method for a reducing mill that adjusts the rotational speed of a rolling roll during rolling of a tip and a trailing end of a tube to be rolled, comprising: drive current and rotation of a motor that drives the rolling roll; Detect the speed, calculate rolling torque from these detection results, detect biting and tailing of the tube from the fluctuation state of the rolling torque, and compare the detected biting point and a predetermined tip control start point. and the time difference between the end of the tail and a predetermined rear end control start time, and determine whether each time difference is within a predetermined range. If the time difference is not within a predetermined range, Tube end control for a reduction rolling mill, characterized in that the tip end control start point and the rear end control start point of the tube are each corrected so that the time difference falls within a predetermined range, and the correction results are learned and used for the next rolling. Starting point learning method.