JPH03142010A - Method for controlling rolling of reeling mill - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention mainly relates to a rolling control method of a reeling mill during the manufacturing process of seamless steel pipes by the Mannesmann plug mill method.

[Conventional technology]

In general, pipe manufacturing using the Mannesmann plug mill method is generally carried out in the following process. First, a steel piece, which is a raw material, is heated to a predetermined temperature in a heating furnace, and then punched and rolled in a piercer to produce a hollow shell.This hollow shell is then stretched and rolled using a plug mill, which is an elongation rolling machine. A raw tube is obtained, which is further rolled using a reeling mill, and then rolled to a fixed diameter using a sizer to produce a seamless tube.

Gluing ξ during this Mannesmann plug mill pipe manufacturing process
As mentioned above, the milling tube rolling by the reeling mill is a process immediately before the final process, so the dimensional accuracy at the exit side of the reeling mill has a large effect on the dimensional accuracy at the exit side of the sizer, that is, the dimensional accuracy of the product.

For this reason, conventionally, the deviation between the actual length of the raw pipe after plug mill rolling and the predetermined target length of the raw pipe is determined, the target outer diameter of the reeling mill is corrected according to this deviation, and the corrected target A method of controlling the rolling position of the rolling rolls to achieve the outer diameter and rolling the tube length on the exit side of the sizer to match the target length (Japanese Patent Application Laid-Open No. 61-88913), or In order to keep the diameter constant, the target thickness reduction amount for each part of the pipe in the axial direction is determined, and the actual thickness reduction amount is calculated based on the torque of the rolling motor and the entrance side material pipe temperature. A method of controlling the rolling roll position of a reeling mill to match the amount of thinning (Special Publication No. 61-6
No. 0721) etc. have been proposed.

[Problems to be Solved by the Invention] In actual reeling mill rolling, the reeling mill rolling speed changes even if the rolling setting conditions are the same, due to the internal lubrication state of the mother pipe, rolling temperature, etc. , the rolling time varies. If the rolling time fluctuates, the dimensions of the raw pipe after reeling mill rolling will not be constant even if the same dimensions of the raw pipe are rolled with the same rolling torque, but none of the above methods can handle such fluctuations in rolling time. Therefore, if the reeling mill rolling time changes due to a change in the internal lubrication state of the raw pipe, the actual length of the raw pipe after reeling mill rolling will be the target raw pipe length value. There was a problem that it did not match.

The present inventors conducted experiments and research in order to eliminate the fluctuation in the actual length of the raw pipe after rolling with a reeling mill due to the variation in rolling time as described above, and found that the elongation of the raw pipe due to the reeling mill, There is a certain relationship between the reeling mill workload (= reeling mill rolling power x rolling time), and in order to correct the length of the reeling mill outlet side tube, the reeling mill rolling time should be taken into consideration. We found that it is desirable to control the amount of work.

Figure 2 is a graph showing the reeling mill work amount (=power of the reeling mill rolling motor x rolling time) on the horizontal axis and the elongation of the raw pipe due to the reeling mill on the vertical axis.
As is clear from this graph, there is a predetermined relationship between the two, and this is expressed as in equation (1) below.

ΔL++ = a X ()P X t) + b
-(1) However, L, ΔLR: Elongation of the raw pipe in the reeling mill I-P = Electric power of the reeling mill rolling motor t: Rolling time of 4 reels a, b: Constants for each dimension and material The present invention This was done based on this knowledge, and its objective is to improve the internal lubrication state of the raw tube.

Even if the reeling mill rolling time changes due to rolling temperature, etc., the actual length of the raw pipe after reeling rolling can be made to match the target length of the raw pipe without being affected by this change, and the length of the raw pipe can be made to match the target length of the raw pipe. The purpose of the present invention is to provide a method for controlling rolling.

[Means to solve the problem]

The rolling control method for a reeling mill according to the present invention calculates the deviation between the actual length of the raw pipe on the entry side of the reeling mill and a predetermined target length of the raw pipe, and adjusts the target rolling of the raw pipe in accordance with this deviation. While setting the amount of work, during rolling of the raw pipe,
The amount of work already rolled and the length of already rolled are sampled, and based on these, the amount of rolling work at the end of rolling of the base pipe is predicted,
The method is characterized in that the predicted rolling workload is controlled to match the target rolling workload.

[Effect]

Accordingly, the present invention can control the target rolling power in order to match the target rolling workload with the predicted rolling workload.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof.

FIG. 1 is a schematic diagram showing the implementation state of the method of the present invention, and in the figure, 1 and 2 are rolling rolls, 3 is a plug, and P is a blank pipe. Each of the rolling rolls 1 and 2 is pivotally supported by a support 4.4 on both sides of the pass line of the blank pipe P, with their respective axes inclined in opposite directions with respect to the pass line.

The shaft end of each rolling roll 1.2 is connected to a single motor M via a gear transmission system 5, and is driven by the motor M to rotate in the same direction as shown by the arrow. It is now possible to Further, each support 4.4 is provided with a rolling down screw 4a, 4a, respectively, so that the opening degree of the rolling rolls 1.2 can be adjusted by means of individual rolling down motors Mz, Ms.

The plug 3 is also formed in a cylindrical shape, is fixed concentrically to the tip of the mandrel 3a, and is connected to both the above-mentioned regular rolling rolls 1.
, 2, and is supported on the pass line of the raw tube P.

After passing through the elongation-rolling process in the plug mill in the previous step, the raw pipe P was sent to a reeling mill, where it was passed between rolling rolls 1 and 2 while being fitted onto the plug 3, and subjected to tube rolling. After that, it is transferred to a sizer for the next process (not shown).

6 is a rolling work calculation device, in which the raw pipe P is the rolling roll 1.
．． 2, the electric power of the motor M1 during rolling is sampled at a predetermined timing, and this is integrated to calculate the rolling work from the time when the raw pipe P is caught by the reeling mill up to the present moment. The amount is calculated and outputted to the sequential control calculation device 10.

Reference numeral 7 denotes a raw pipe speed detector, which is installed at the entrance side of the reeling mill, and its detected value is taken into the rolling length calculating device 9 and integrated, and the data from the time when the raw pipe is bitten to the present time is calculated. The pre-pressurized extension length for the raw pipe P is calculated, and this pre-pressurized extension length is output to the control calculation device 10.

The control/arithmetic unit 10 calculates the difference between the actual length of the raw pipe after plug mill rolling and the target length of the raw pipe after plug mill rolling, and calculates the difference between the input side of the reeling fruit that is manually inputted prior to friction rolling, that is, the actual length of the raw pipe after plug mill rolling, and the target length after plug mill rolling. The target rolling work of the reeling mill is determined according to the length of the pipe and the type of the raw pipe, and the initial rolling time and rolling power of the reeling mill are set based on the target rolling work of the reeling mill. Start ring mill rolling.

As the rolling time, a standard rolling time predetermined according to the type of raw pipe is used, and the rolling power is calculated according to the following formula (2).

Target rolling power = Target rolling work amount / Standard rolling time... (
2) Rolling is started under the initial conditions using such standard rolling time and target rolling power.

On the other hand, during friction rolling by the reeling wheel, the rolling work calculation device 6. The rolled work amount and already rolled length of the raw pipe are taken in from the rolled length calculation device 8 at a predetermined timing, and the rolling work of the raw pipe at the end of tube rolling is predicted according to the following formula (3). do.

Next, the deviation between this predicted rolling work and the previously determined target rolling work is calculated, and in order to eliminate this deviation, in other words, to correct the target rolling power of the reeling mill, a signal corresponding to this is sent. It is output to the reduction motor control device 11. The lowering motor control device 11 obtains control signals for the motors MZ and M3 based on the input signals, and controls the motors MZ and M3.
Output to.

As a result, when the relationship is that the actual length of the raw tube at the entrance of the reeling straw > the target length, the reeling mill rolling work (= reeling plan rolling power x rolling time) will be increased.
Further, when there is a relationship between the actual length and the target length after reeling mill rolling, control is performed to reduce the reeling mill rolling workload.

The actual rolling speed differs from the standard rolling speed due to differences in the internal lubrication state of the raw tube or the temperature of the raw tube, and due to this, the actual rolling time and the standard rolling time set as the initial conditions do not match. Even if the actual reeling mill rolling work cannot be made to match the target rolling work with the reeling mill target rolling power used as the initial condition, the roll opening By controlling, in other words, modifying the target rolling power,
This will allow for consistency between the two.

In addition, when modifying this target rolling power, the existing pressure extension,
By predicting the remaining rolling time based on the standard rolling time and the raw pipe length, the actual pipe length can be obtained with higher accuracy.

Further, in the above-described embodiment, the case where the roll opening degree is adjusted is explained, but the same effect can be obtained by adjusting the plug position.

Furthermore, the control calculation unit IO manually inputs the actual pipe length after glue-ring rolling for each raw pipe, the target raw pipe length after sizer rolling, and the actual length after sizer rolling, and calculates the reeling mill target rolling work. A learning function for modifying the quantity calculation formula may be provided.

〔effect〕

As described above, in the method of the present invention, the target rolling work is determined according to the deviation between the actual length of the raw pipe at the entrance side of the reeling mill and the predetermined target length of the raw pipe, and the rolling work of the raw pipe is sequentially performed during rolling. The amount of work at the end of rolling is predicted and the rolling power is corrected so that the predicted amount of rolling work matches the target amount of rolling work, so even if rolling time fluctuation factors occur, it will not be affected by this and will match the target value. The present invention has excellent effects such as being able to

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the implementation state of the method of the present invention, and FIG. 2 is a graph showing the relationship between the rolling work of the beam mill and the elongation of the raw pipe in the reeling mill.

Claims (1)

[Claims] 1. Find the deviation between the actual length of the raw pipe at the entrance side of the reeling mill and the predetermined target length of the raw pipe, and set the target rolling work for the raw pipe in accordance with this deviation. During rolling, sample the already rolled work and already rolled length, predict the rolling work at the end of rolling of the mother pipe based on these, and match the predicted rolling work with the target rolling work. A rolling control method for a reeling mill, characterized by controlling the rolling of the reeling mill as much as possible.