JPS6360014A - Hydraulic rolling reduction controller for mandrel mill - Google Patents

Abstract

PURPOSE:To improve a stopping accuracy of a cylinder positioning by providing a hydraulic servo system for the cylinder positioning to control a positional deviation of a hydraulic cylinder and by arranging an automatic offset correcting circuit to correct the offset of a neutral position. CONSTITUTION:Hydraulic units 5a-5d possessed of a servovalve 51, a differential transformer 54 are provided on each hydraulic cylinder 2a-2d and servo calculating parts 4a-4d are disposed. On each servo arithmetic part 4a-4d, together with a servo amplifier 43, a D/A transducer 41, correcting arithmetic circuit 42, sample hold circuit 31, etc., are provided respectively. In this mechanism, the pressure of the pressure oil feeding to the cylinders 2a-4d are inputted into the correcting arithmetic circuit 42 through a detector 52, a digital compensating feed back control is performed for the command signal to feed to the servo amplifier 43. Therefore, the stopping accuracy of the cylinder position is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mandrel mill hydraulic pressure reduction control device, and more specifically, to reduce cropping due to thickening of the tube end in a stretch reducer in the next process. The present invention relates to a hydraulic pressure reduction control device for preforming a tube end thinly into a tapered shape using a mandrel mill.

[Conventional technology]

In a hot jointless steel pipe production line that uses a retch reducer as the final finishing process, cropping increases due to the phenomenon of tube end thickness intensification at the reducer, forcing a significant drop in yield. One way to overcome this drawback is to pre-form the corresponding pipe end into a thin tapered shape during rolling in a mandrel mill, which is the pre-process, and to offset this by the above-mentioned thickening phenomenon. be. Special Public Service No. 51-4382
Publication No. 5 discloses a mandrel mill hydraulic reduction control for B, in which several drum-shaped reduction rolls are arranged around the rolled raw pipe in a stand Z, and each roll is Each cylinder is driven by a separate hydraulic cylinder for rolling down, and the rolling position of all cylinders is moved at a controlled speed as the raw pipe passes, thereby preforming the pipe end into a tapered shape. In this case, the positioning control of each cylinder must of course be performed at high speed and with high precision, and furthermore, it is necessary to avoid as much as possible the deterioration of the positioning and stopping accuracy of the cylinders due to the influence of oil drift, etc. However, in general feedback control The proportional FFJI control method cannot fully achieve the objective of 1.Therefore, phase compensation can be considered as another method to improve the positioning and stopping accuracy, but in this case, it is relatively difficult to select the compensation constant. .That is,
Improving stopping accuracy and ensuring high-speed response are in a contradictory relationship, and finding a compromise requires repeated trial and error.

[Point m to be solved by the invention] i2a of the present invention eliminates the drawbacks of the prior art described above, and
It is an object of the present invention to provide a mandrel mill hydraulically pressurized full H&IT device for forming tube terminals, which can ensure long-term stopping accuracy without impairing the high responsiveness of sill positioning control.

[Means for solving problems]

In order to achieve the above-mentioned problems, in the mandrel mill hydraulic pressure control device for forming tube terminals of the present invention, in order to preform the wall thickness of the tube end into a thin tapered shape when the tube end of the rolled blank tube passes through the rolling line. Hydraulic cylinder position servo control for controlling a hydraulic cylinder control valve so as to eliminate deviation between the actual position of the hydraulic cylinder and the commanded position of the hydraulic cylinder for positioning control of a plurality of reduction rolls arranged across the width. and an automatic offset correction circuit that samples the deviation at periodic sampling timing and corrects the offset of the neutral point of the servo control system based on a correction value according to the sampling result until the next sampling point. There are few.

In one embodiment of the invention, the automatic offset correction circuit includes adjustment means for variably adjusting the correction value.

[Effect]

In the hydraulic pressure reduction control device of the present invention, as is clear from the above-described configuration, the automatic offset correction circuit periodically automatically corrects the neutral point drift in the servo system, and in this case is substantially involved in the loop gain of the servo system. do not. Furthermore, if the adjustment means is provided, the optimum correction effect can be obtained by adjusting the correction gain yA.

For a better understanding of the present invention, preferred embodiments of the present invention will be described below with reference to the drawings.

〔Example〕

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.
The outline of the configuration of the hydraulic reduction system rim for the hydraulic syringe family 'l 2n to 2d of the book is shown, especially the N
o. Regarding the 4-cylinder 2d, the configuration contents of the servo calculation section and hydraulic unit are also shown.

In FIG. 1, a block 10 conceptually represents a higher-level processor for rolling control, and a hydraulic pressure reduction command as a shilling position setting command signal is given from this block 10 as a binary signal of, for example, 16 bits.

The above-mentioned shilling position setting command (Igo number) is input to the shilling position command digital calculation unit 3, where the shilling position command to the servo calculation units 411 to 4d of each shilling is calculated. It may be a microcomputer.As will be described later, the Schilling position command outputted from this calculating section 3 is a digital number 42 corresponding to the deviation between the actual Schilling position and the Schilling position setting command, and this calculating section 3, a timing signal for sampling this deviation is given to each servo calculation unit, for example, every few seconds.

The servo calculation units 4a to 4d have digital inputs that control hydraulic units 51 to 5d that control the drive oil pressure of each shilling.
It is an analog output type control amplifier, and its configuration is NO,
The four-sabot calculation unit will be described later.

Cylinder output position detectors 16a-6d, such as Magnescale, are attached to each cylinder 18-1d.

As shown for unit No. 4, the hydraulic units 5a to 5d include a servo valve 51 that controls the supply of pressure oil to the cylinder 2d, and are also provided with a pressure detector 52 that detects the pressure of pressure oil to the cylinder. There is. The servo valve 51 is equipped with an electro-mechanical converter 53 for driving it and a differential transformer 54 for position feedback of its B1 mechanical output.

The servo calculation units 4a to 4d convert the cylinder position command (digital deviation signal) from the digital calculation unit 3 into an analog signal, as shown for the magnetic 4 servo calculation unit 4d.
/A conversion @j! 41, and a correction calculation section l? which performs various correction calculations on the analog signal from this D/A converter 41. 1s
42, a servo amplifier 43 that drives the electro-mechanical converter 53 of the servo valve 51 using the output of the correction calculation section g2i42 as a command input, and a servo amplifier 43 that receives the timing signal from the digital calculation section 3 and generates the digital deviation signal. A sample hold circuit 31 that samples and holds it until the next timing signal comes, and a D/A that converts the digital output of the sample hold circuit 31 into an analog value.
The outputs of the converter 32 and the D/A converter 32 are
lil XI! Offset correction gain adjustment to be adjusted and given to the correction calculation circuit! ! ! The difference between the PJ33 and the position feedback signal from the differential transformer 54 is adjusted in gain and given to the servo amplifier 43 as a differential input! Dbl・
a differential pressure compensation circuit 45 that adjusts the span and gain of the detection output of the pressure detector 52 and inputs it as a compensation signal to the compensation calculation circuit 42; and the position detector 6d.
A detector 46 generates an up signal and a down signal from the output of the detector 46, and an up/down counter that counts these up signals and down signals and outputs a counted digital output to the digital calculation unit 3 as a cylinder position signal of, for example, a 16-bit binary signal. 47, a D/A converter N48 that converts this digital Schilling position signal into an analog signal, and a differentiation port L849 that differentiates this converted analog Schilling position signal and inputs it to the correction calculation circuit 42 as a speed compensation signal.
It is equipped with

The digital calculation section 3 calculates the cylinder position command from the cylinder position command digital signal from the host program controller and the detected cylinder position digital signal (No. /A converters 31 and 41 and correction calculation section 42
The signal is supplied to the servo amplifier 43 via the servo amplifier 43.

Although the above description of the configuration of the servo calculation section has been given for the servo calculation section for No. 4 cylinders, the same applies to the servo calculation sections for No. 1 to Ha 3 cylinder m.

In the mandrel mill hydraulic pressure reduction control device having the above configuration, the actual reduction position of each cylinder is transmitted to the digital calculation unit 3 from the position detectors 6a to 6d, and is detected by the servo calculation units 48 to 4.
It is given as a digital signal as a count value by an up/down counter (47) via d. Top pro controller 1
The reduction signal from 0 is a cylinder position command that changes in a pre-programmed pattern to offset the phenomenon of tube end thickening in the next process stretch reducer that occurs at the tube end of the rolled blank tube. The command is digital/jl
Er1. l! 1153 to all servo calculation units 4a to 4
d as a digital command signal, and the start timing of the control is rolling T: when the pipe end of the pipe passes,
It is given using the on/off signal of the mill's load relay.

To explain the operation of the cylinder for No. 4 shilling 4d, the servo amplifier 43, which has a minor loop formed by the differential transformer 54 and the amplifier 44, drives the electro-mechanical converter 53 of the servo valve 51 in response to command input. The servo valve 51 correspondingly supplies pressure oil to the cylinder 4d. The hydraulic pressure to the cylinder 4d is detected by a pressure detector 52, and is given to the correction calculation circuit 42 via a differential pressure compensation circuit 45, which applies pressure compensation feedback to the command signal to the servo amplifier. There is. The shilling position is detected by the position detection PB6d, and sent to the calculation unit 3 as a digital signal (No. 3) by the 7-up down counter 47 via the detector 46.
A digital deviation signal is calculated from the digital position from 0, the command signal, and this digital position detection signal, and this is provided as an analog signal to the correction calculation circuit 42 via the D/A converter 41 of the servo calculation section 4d. . The digital cylinder position detection signal from the up/down counter 47 is also input to a differentiation circuit 49 via another D/A converter 48, and its differential output is input to the correction calculation circuit 42 as a speed compensation signal. . The correction calculation port W842 uses the correction input signals of the differential pressure compensation and speed compensation to calculate the D/
The analog/4G command signal from the A converter 41 is corrected and then given to the servo amplifier 43.

As a result, the position *J control of the cylinder 2d by the servo valve 51 becomes digital feedback mm of the actual position according to the digital position command signal, and this is the same for all cylinders, and each cylinder is controlled by a highly responsive digital control system. Therefore, ultimate high-speed and high-precision cylinder positioning is possible for all cylinders. In addition, this servo system is compensated for speed by the speed detection signal, so when a sudden change in command occurs, the damping effect due to speed compensation is improved and transient characteristics are smoothed out. It also increases the sex.

The sample hold circuit 31 samples the digital deviation signal from the calculation section 3 intermittently at a certain appropriate period, and if a difference occurs between the setting command signal and the actual cylinder position detection signal at the time of sampling, A sampling value corresponding to the deviation is held, converted into an analog value by the D/A converter 32, and applied to the correction calculation circuit 42 via the adjuster 33 in a direction to eliminate this deviation.

This offset correction value is held until the next timing signal arrives. By adjusting the key MVs33, it is possible to easily obtain a very optimal offset correction effect. It is best to determine the correction timing based on the rolling performance of the mandrel mill. For example, for rolled stock pipes, it should be done once in synchronization with the rolling start command, and an interlock should be applied during rolling to prevent offset correction. , so that when not rolling, corrections are made at intervals of several seconds, for example, several times before the next rolled blank tube is bit into the mill.
It is better to generate correction timing periodically every second.

In this case, it goes without saying that an upper limit is set for the amount of offset that can be corrected at the negative correction timing, or an upper limit is also set for the total offset in multiple corrections.

〔Effect of the invention〕

As described above, according to the present invention, the neutral point drift of the servo amplifier due to changes in oil temperature, etc. in the servo system for cylinder control is automatically offset corrected using periodically intermittent position deviation sampling values. Therefore, it is possible to maintain good cylinder position stop accuracy for a long time without impairing the high responsiveness of the control system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, la and ld are rolling rolls, 2a to 2d are hydraulic cylinders for rolling down, 3 is a digital calculation unit, 4a to 4d are servo calculation units, 5a to 5d are hydraulic units, and 6a to 6d
1 is a position detector, 10 is a host processor, 31 is a sample hold circuit, 321. fD/A converter, 33 is offset correction gain adjustment'! i unit, 41 is a D/A converter, 42 is a correction calculation circuit, 43 is a servo amplifier, 44 is a differential gjJ+
- Lance amplifier, 45 is a differential pressure compensation circuit, 46 is a detector, 47 is an up/down counter, 48 is a D/A converter,
49 is a differential circuit, 51 is a servo valve, 52 is a pressure detector, 53 is an electro-mechanical conversion type, and 54 is a difference! ! il+ +
- indicates a lance.

Claims (1)

[Claims] 1. Taper the wall thickness at the end of the rolled raw pipe by controlling the positioning of a plurality of reduction rolls arranged across the width of the rolling line using separate hydraulic cylinders when the rolled raw pipe passes through the pipe end. In a mandrel mill hydraulic pressure reduction control device for thinly preforming into a shape, a hydraulic cylinder position servo control system that controls a hydraulic cylinder control valve so as to eliminate the deviation between the actual position of the hydraulic cylinder and the commanded position, and a periodic The present invention is characterized by comprising an automatic offset correction circuit that samples the deviation at a sampling timing and performs offset correction of the neutral point of the servo control system based on a correction value according to the sampling result until the next sampling point. Mandrel mill hydraulic pressure reduction control device. 2. The mandrel mill hydraulic pressure reduction control device according to claim 1, wherein the automatic offset correction circuit includes adjustment means for variably adjusting the correction value.