JPH06154834A - Controller for wall thickness of tube end for stretch reducer - Google Patents

Abstract

PURPOSE:To provide a tube end thickness controller of a stretch reducer which can decide a revolving speed control timing. CONSTITUTION:A control circuit 7 for a stand roll driving motor, a 1st simulator circuit 8 to a simulate a loadless state and to output a loadless current signal, a 2nd simulator circuit 9 to simulate a loaded state and to output a loaded current signal and a current deviation calculating part 10 to input a loadless current signal and a loaded current signal and to calculate a detecting current signal are provided on the controller 5 for a roll driving motor in a tube end thickness controller of a stretch reducer. A thick wall is restrained from being generated at the front and rear ends of the tube by containing a detecting circuit 11 for biting and passing timing detected as the timing for biting in and passing through the rolling stock at the stand when a detecting current signal from the current deviation calculating part 10 exceeds a preset threshold level and steeply rises.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe end wall thickness control device for a squeeze rolling mill, and more particularly to a wall thickness suppressing device for suppressing thick wall thickness at the front and rear pipe ends of a squeeze rolling mill (stretch reducer). The present invention relates to a thickness control device.

[0002]

2. Description of the Related Art A drawing rolling mill is a kind of continuous rolling mill, and usually 10 to 30 stands are arranged at roll intervals of about 300 to 400 mm. In the rolling of a pipe by a squeeze rolling mill, the rolled material (hereinafter simply referred to as a raw pipe) that has been heated is subjected to an outer diameter reduction in a row of rolls incorporated in a continuous stand in a state where an axial tension is applied. The tension in the axial direction is adjusted by the difference in the roll peripheral speeds of the stands that are placed one behind the other, and the degree of wall thickness processing is adjusted.

In this case, as compared with a steady state in which the raw pipe is bitten in all the stands, a transitional state in which the pipe is not bitten in all the stands, such as when the tip of the pipe is bitten in the roll stand. Since the tension at the pipe end is smaller than that at the time of central rolling of the pipe, 1.5 to 2 m
A thick tube end thick part is generated. This portion must be cut off as a crop, resulting in a very large loss in yield.

As a method of suppressing the thick wall phenomenon occurring at both ends of the pipe as described above, for example, in Japanese Patent Publication No. 45-1341, a motor current value is used to prevent the pipe from being caught or slipped out at each stand. By detecting the timing,
A method has been proposed in which the roll peripheral speed is controlled to increase the amount of stretch for processing. Further, in JP-A-56-77010, the basic pattern is the rotation speed ratio of each roll when the tube tip passes through the final stand, and when the tip engages with the initial stand with respect to the basic pattern. Rolling is started with a pattern in which the rotation speed ratio of each roll is higher than that of the basic pattern, and the pattern of each roll rotation speed ratio is changed toward the basic pattern as the leading edge moves toward the final stand. While rolling, after the leading end has passed the final stand, after continuing rolling in a basic pattern until the pipe rear end reaches the predetermined stand, after the rear end passes the predetermined stand, the ratio of each roll speed Has been proposed to finish rolling at a high roll speed ratio.

Alternatively, in Japanese Patent Laid-Open No. 60-221108, the timing of biting or slipping out of a predetermined stand at the front end or rear end of the tube is detected by a detector installed in correspondence with the predetermined stand. There is disclosed a method of controlling a roll peripheral speed of an upstream stand when a predetermined part or a predetermined part of a rear pipe is rolled in a predetermined upstream stand and a downstream stand.

Further, in Japanese Patent Laid-Open No. 61-108414, the tension between adjacent stands is measured, and the deviation between the measured tension and the target tension at each portion in the longitudinal direction of the tube is calculated. There is disclosed a method in which the rotation speed of a stand for rolling is controlled so that the deviation becomes zero, and the rolling speed of the stand for rolling a portion having no deviation is the reference rotation speed.

[0007] Further, JP-A-4-138812, based on the aperture rotation speed of the roll driving motor of a rolling mill (angular velocity) w and the current value I _a, subtracting the acceleration and deceleration torque from all the generated torque of the motor the actual rolling torque T _L Te, T _L
= Kφ · I _a −J · dw / dt (where Kφ is the field constant, J is the motor + roll inertia), and the actual rolling torque output from the rolling torque calculation unit From the biting and trailing edge timing detection unit that detects the biting and trailing edge timing of the rolled material and outputs it to the downstream roll rotation speed control unit, and the upstream biting
Roll rotation that calculates the rotation speed control timing of the roll stand based on the biting and tail slipping timing of the rolled material input from the trailing edge timing detection unit, and outputs the rotation number control command to the roll drive motor control unit of the roll stand Number control unit, find the deviation between the actual rotation speed measurement value and the rotation speed command value,
A pipe end wall thickness control device has been proposed, which includes a roll speed control unit and a rotation speed deviation control unit that outputs a rotation speed control amount change command at the time of leading and trailing end rolling.

[0008]

However, the above-mentioned conventional example has various problems. That is, first of all
In the method of No. 45-1341, the motor current value is used to detect the biting and slipping out of the pipe, and it is possible to easily detect the biting other than when the motor is accelerating / decelerating. The acceleration / deceleration current is included in the motor current value, so it is difficult to detect bite / miss.

In the method of Japanese Patent Laid-Open No. 56-77010, the theoretical passage time and the actual passage time between stands are different even if the rolling setup is the same because the outer diameter, wall thickness, and temperature of the inlet pipe differ depending on the rolling opportunity. Deviation occurs, and the rotation speed control timing and the bite / bottom out timing are not appropriate. JP 60-
In the method of No. 221108, the reduction rolling mill is composed of 10 to 30 roll stands, the number of detectors to be installed is large and the installation cost is high, and the frequency of erroneous recognition of the tube position may be increased. . In addition, since the normal roll stand is designed to make the width of the roll stand as narrow as possible in order to shorten the crop length and the roll interval as narrow as possible, it is difficult to apply it to existing equipment.

In the method of Japanese Patent Laid-Open No. Sho 61-108414, since a tension measuring device is installed for each stand, the frequency of failure occurrence is high, and there are many obstacles when changing rolls. From the point of view, it is not so preferable. In the case of Japanese Unexamined Patent Publication No. 4-138812, when the actual rolling torque T _L is calculated, the motor angular velocity w needs to be differentially calculated, which is disadvantageous in that it is weak against noise. Of course, it is conceivable to use a filter as a countermeasure against the noise,
If so, a detection delay will occur. Moreover, since the use of current I _a according to actual, so that the mechanical delay in its value.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and accurately detects the timing at which the tip of the pipe end is caught and the trailing end of the pipe at the end of the pipe in a reduction rolling mill. It is an object of the present invention to provide a pipe end wall thickness control device for a reduction rolling mill that determines the rotation speed control timing.

[0012]

SUMMARY OF THE INVENTION The present invention is directed to a rolling stand arranged in a tandem in a plurality of stages for rolling a rolled material, a roll drive motor for driving a roll of the rolling stand via a speed reducer, and the roll. A motor speed detector coupled to the rotation shaft of the drive motor to detect the rotation speed of the roll drive motor, and the motor speed from the motor speed detector is fed back to control the rotation of the roll drive motor at a predetermined rotation speed. In a pipe end wall thickness control device for a reduction rolling mill comprising a roll drive motor control unit and a command rotation speed calculation unit for instructing the roll drive motor control unit of the rotation speed, the roll drive motor control unit is set to the command rotation speed. The roll drive motor is rotationally controlled at a predetermined rotation speed based on the rotation speed command from the number calculation unit, and the motor speed from the motor speed detector is fed. A stand-roll drive motor control circuit that backs up, and a first that outputs a no-load current signal by simulating a no-load state of the stand-roll drive motor control circuit based on a rotation speed command from the command rotation speed calculation unit. A simulator circuit, and a second simulator for simulating the load state of the roll drive motor control circuit based on the rotation speed command from the command rotation speed calculation unit and the motor speed from the speed detector to output a load current signal. A circuit, and a current deviation calculator that inputs a no-load current signal from the first simulator circuit and a load current signal from the second simulator circuit to calculate a detection current signal,
The bite / butt that is detected as the biting / bottom-out timing of the rolled material at the stand when the detection current signal from the current deviation calculator exceeds a preset threshold value and shows a sharp rise Omission timing detection circuit,
Is a pipe end wall thickness control device for a reduction rolling mill.

[0013]

[Operation] The inventors conducted extensive research and experiments to solve the above problems, and as a result, calculated when excluding the influence of the acceleration / deceleration current shown in FIG. It was found that the degree of change of the detected current signal showed a steeper rise than the degree of change of the rolling torque signal as shown in FIG. 4 (b), and the present invention was completed based on this finding.

That is, according to the present invention, in order to exclude the influence of the current during acceleration / deceleration, the deviation between the load current signal and the no-load current signal is detected by using two simulator circuits, a no-load state and a load state. Is detected as a current signal for use in the vehicle, and when the detected current signal shows a steep rise exceeding a predetermined threshold value SL, it is used as a biting / flanking timing signal. The timing can be detected, and by this, it is possible to change the rotational speed control amount at the time of pipe end rolling in a timely manner.

[0015]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a system diagram showing an outline of the control device of the present invention. In the figure, 1 is a rolling stand arranged in a tandem of a reduction rolling mill to roll a plurality of stages (for example, 24 stages) of a raw pipe P, and 2 is a roll drive motor for driving rolls of the rolling stand 1 via a speed reducer 3. 4 is connected to the rotary shaft of the roll drive motor 2 and is connected to the roll drive motor 2
A motor speed detector such as a pulse generator for detecting the number of revolutions of the roll drive motor 5 is fed back with the motor speed from the motor speed detector 4 to control the roll drive motor 2 at a predetermined number of revolutions. 6
Is a command rotation speed calculation unit for commanding the rotation speed to the roll drive motor control unit 5.

The structure of the roll drive motor control section 5 will be described by taking the control section of the No. i stand in FIG. 2 as an example. The No. i stand roll drive motor control circuit 7 will be described.
A first simulator circuit 8 for simulating the no-load state of the roll drive motor control circuit 7, a second simulator circuit 9 for simulating the load state of the roll drive motor control circuit 7, and a current deviation calculator 10. , Bite
It includes a trailing edge timing detection circuit 11.

In the roll drive motor control circuit 7, the rotation speed of the roll drive motor 2 is controlled based on the command signal from the command rotation speed calculator 6 and the motor speed feedback from the motor speed detector 4 is performed. Is done. On the other hand, in the first simulator circuit 8, the magnitude of the no-load current signal in the no-load state is simulated on the basis of the command signal from the command rotation speed calculation unit 6, and the result is sent to the current deviation calculation unit 10. Output.

In the second simulator circuit 9, the magnitude of the load current signal in the load state is simulated based on the command signal from the command rotation speed calculation unit 6 and output to the current deviation calculation unit 10. . Therefore, the current deviation calculator 10 performs a comparison operation with the no-load current signal from the first simulator circuit 8 and calculates the deviation as a detection current signal. Therefore, this detection current signal is not affected by the acceleration / deceleration of the roll drive motor 2. When it is determined that the current signal for detection exceeds a preset threshold value and a steep rise / fall occurs, the jamming / flanking timing detection circuit 11 detects jamming /
It is detected as a trailing edge timing signal and output to the No. i stand roll drive motor control circuit 7.

The second simulator circuit 9 is provided with a function of calculating the rolling torque according to the motor speed fed back from the motor speed detector 4 and outputting it to the bite / bottom missing timing detection circuit 11. As a result, when the rolling torque signal that rises sharply beyond the preset threshold value is input earlier than the detection current signal, it is used as the biting / flanking timing signal instead of the detection current signal. Will be adopted.

Here, it is necessary to determine the threshold value preset in the above-mentioned bite-in / bottom-out timing detection circuit 11 for each size of the raw pipe P to be rolled to determine its pattern. When the method of the present invention was applied when rolling a finished pipe having an outer diameter of 34.0 mmφ and a wall thickness of 4.0 mmt with a stretch reducer consisting of 24 stands, the deviation in the wall thickness in the longitudinal direction of the pipe was compared with a tolerance of ± 10%. As shown in FIG. 3, it was possible to reduce the amount to about half that of the conventional one.

[0021]

As described above, according to the present invention,
The deviation value of the current in the loaded state and the unloaded state is calculated using two simulator circuits, and the timing of its steep rise is used as the biting / flanking timing signal, so it is not affected by the acceleration / deceleration of the motor. With this, it is possible to accurately detect the timing of biting and slipping out, which makes it possible to change the number of revolutions control at the time of rolling at the end of the pipe for each rolling opportunity, greatly reducing the loss of pipe end crops. It is possible to improve the yield.

[Brief description of drawings]

FIG. 1 is a system diagram showing an outline of a control device of the present invention.

FIG. 2 is a block diagram showing a configuration of a roll drive motor control unit of the present invention.

FIG. 3 is a characteristic diagram showing a wall thickness deviation distribution in the pipe longitudinal direction.

FIG. 4 is a characteristic diagram showing the principle of the present invention.

[Explanation of symbols]

 1 Rolling Stand 2 Roll Drive Motor 3 Reducer 4 Motor Speed Detector 5 Roll Drive Motor Controller 6 Command Rotation Speed Calculator 7 Stand Roll Drive Motor Control Circuit 8 First Simulator Circuit 9 Second Simulator Circuit 10 Current Deviation Calculation Part 11 Biting and trailing edge timing detection circuit P Element tube (rolled material)

Claims (1)

[Claims] 1. A rolling stand arranged in a tandem in a plurality of stages to roll rolled material, a roll drive motor for driving rolls of the rolling stand via a speed reducer, and a rotary shaft of the roll drive motor. A motor speed detector that detects the rotation speed of the roll drive motor, a roll drive motor control unit that feeds back the motor speed from the motor speed detector to control the rotation of the roll drive motor at a predetermined rotation speed, In a pipe end wall thickness control device for a reduction rolling mill, which comprises a command rotation speed calculation unit for commanding a rotation speed to a roll drive motor control unit, the roll drive motor control unit controls the rotation speed command from the command rotation speed calculation unit. A stand roll that controls the rotation of the roll drive motor at a predetermined rotation speed based on the above and feeds back the motor speed from the motor speed detector. A drive motor control circuit, and a first simulator circuit that simulates a no-load state of the stand roll drive motor control circuit based on a rotation speed command from the command rotation speed calculation unit and outputs a no-load current signal, A second simulator circuit for simulating a load state of the roll drive motor control circuit based on a rotation speed command from the command rotation speed calculation unit and a motor speed from a speed detector to output a load current signal; A current deviation calculation unit for calculating a detection current signal by inputting a no-load current signal from the first simulator circuit and a load current signal from the second simulator circuit, and a detection unit for detection from the current deviation calculation unit When the current signal exceeds the preset threshold value and shows a sharp rise, it is detected as the biting and trailing edge timing of the rolled material at the stand. - biting that
A pipe end wall thickness control device for a reduction rolling mill, comprising: a trailing edge timing detection circuit.