JPH0399720A - Coiling method of strip in continuous hot strip mill - Google Patents

Abstract

PURPOSE:To coil a tight coil by raising stepwise the lag rate of a hot run table roller corresponding to the progress of the tail end of a strip. CONSTITUTION:In a method that the strip 1 rolled with a continuous hot strip mill 2 is coiled while a prescribed tension is applied with a coiler 5 through hot run table rollers 3 divided into plural sections, when the tail end is left from the final finishing stand Fn, the back tension of the tail end of the strip is kept constant by stepwisely enlarging the lag rate L (%) that is expressed by the undermentioned formula in each section of the hot run tables. Wherein, Vs; speed of strip (m/min), VHR; peripheral speed of hot run table (m/min) are defined. By this way, the coiled shape of the strip can be made tight.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for winding up a stock pump in a continuous hot rolling mill.

<Prior art> Normally, after the tail end of the strip rolled in a continuous hot rolling mill passes through the final finishing stand, tension control is performed using the rollers of the hot run table, pinch rolls, and coiler. This is generally done with a mandrel.

That is, while the strip is on the finishing stand, tension is applied between the finishing stand and the coiler, but when the tail end of the strip passes through the final finishing stand, the tension is applied between the runtable roller group, the pinch roll, and the coiler. By controlling the rotational speed of the pinch rolls and coiler, the tension is kept constant and the material is wound up.

However, with this winding method, when the tail end of the coiler passes through the final finishing stand, the tension between the coiler and finishing stand is released all at once, resulting in an instant no-tension state, and the tension balance is affected. In addition to the large collapse of the coil, which causes poor coil winding, a phenomenon called "driving" occurs in which the strips become loose, and in extreme cases, the loosened strips overlap and get caught in the pinch rolls, causing what is called "board breakage". This may occur.

As a means to prevent such tension imbalance and 'driving in', for example, as disclosed in Japanese Patent Application Laid-Open No. 57-271356, before the tail end of the strip passes through the final finishing stand, a vinyl roll is driven. There is a method of controlling the winding tension by reducing the speed command to the motor control part in a ramp-like manner, and as disclosed in Japanese Patent Application Laid-open No. 110122/1983, the winding tension of the strip is controlled from τJ to the tail end. The back tension is maintained by the finishing mill, pinch rolls and front-stage pinch rolls until the strip passes through the final finishing stand, and the hack tension is maintained by the pinch rolls and front-stage pinch rolls after the tail end of the strip passes through the final finishing stand. A method for controlling the winding tension has been proposed.

<Problems to be Solved by the Invention> However, in the former method of JP-A-57-27856, the tension between the finishing stand and the coiler mandrel suddenly loses its balance after the strip passes through the final finishing stand. Therefore, the winding shape is a method to prevent the so-called "telescope" where the edges of the strip in the width direction are not aligned, and even if it prevents the tension balance from collapsing, the shape of the strip will be removed after the stand is removed. There is a drawback that the tension cannot be maintained stably from the time until the completion of winding.

In addition, in the latter Japanese Patent Application Laid-open No. 1-110122, it is stated that: ■ Materials with a high coiling temperature undergo grain growth due to the strong pressure of the pinch rolls, and ■ Thrust occurs due to the back tension maintained by the two pinch rolls. ■ In order to maintain a constant tension, it is necessary to increase the reduction of the pinch roll as the strip is wound, and uneven wear of the single gauge pinch roll can cause poor winding. There are drawbacks such as.

The present invention provides a method for winding a strip in a continuous hot rolling mill, which is designed to solve the problems of the prior art, such as ``driving in'' of slips, ``board cutting'', and ``put telescope''. The purpose is to offer.

Means for Solving the Problems> The present invention provides a method for winding a strip rolled in a continuous hot rolling mill onto a coiler through a hot run table that is divided into a plurality of sections while applying a predetermined tension. When the tail end of the strip leaves the final finishing stand of the hot rolling mill, the lag rate L (%) V for each section of the hot run table defined by the following formula:
, -V, □ L= This is a method of winding a slip in a continuous hot rolling mill, which is characterized by keeping the end hack tension constant.

<Function> The inventor of the tree focused on the fact that a coil wound with a certain lag rate becomes loose as the winding becomes thicker, and scratches often appear in the next process. As a result of experiments in which the tail end of the strip leaves the final finishing stand, the back tension can be kept constant by increasing the lag rate of the hot run table roller in stages as the tail end progresses. It was discovered that the winding of the coil does not become loose because the coil can be kept in a stable state.

This will be explained in detail below.

As shown in Fig. 1, a plurality of finishing stands F...17
The rolled strip 1 is finished by hot rolling R2 consisting of Pontlant table rollers 3. It passes through a pinch roll 4 and is wound up by a coiler 5. The real runtable roller 3 is divided into six sections, for example 1 (R8-11R6), and the speed can be controlled for each section.

Figure 2 shows the strip speed V s (m/m+n) and the pot run table roller circumferential speed VIIR (m/m1n).
This shows the speed pattern typical of boat fishing.

First, regarding the stripping speed V, the first finishing stand F of the hot rolling mill 2 is set to 'F+ON point'.

In, speed ■,. The strip I that is bitten by °
When it wraps around the coiler 5 at the 'C-on point', the speed increases at a certain acceleration rate and reaches the maximum speed of V3.411. The tail end of strip 1 begins to decelerate at any designated finishing stand and reaches final finishing stand F. The speed is reduced to a certain level VSn at the off point ``F,'' and deceleration is started all at once at the hot run table point ``CX point'', and when the tail end of the strip reaches the binge roll 4 ``I'l+
At the "off point", the speed is reduced to 300 to 500 rpm and winding is completed.

On the other hand, regarding the pot run table roller circumferential speed Vllll+, the point at which the strip tip wraps around the coiler 5 is ``C''.
Until the on-point, the strip is driven at a certain lead rate at a peripheral speed VIIRO, which is faster than the Zunawa strip speed V, but
At the starting point of winding to the coiler 5, the peripheral speed is synchronized with the strip speed at the C-on point.

F7 where the tail end of the strip passes through the final finishing stand F.
17 points" (7) iiJ (7J From a certain point "F, point", it begins to decelerate at a lag rate determined by the following formula (1), and the final finishing stand F at the tail end of the strip reaches point F117' The pot run table roller circumferential speed VIIR has completed deceleration at ° and maintained a certain lag rate with respect to the slip I/slip speed V.
to complete the winding.

In the conventional example in which the coil is wound at a constant lag ratio, as the tail end of the strip passes through each section of the roller 1 and the run table roller 3, the back tension T,
(kg f/mm") becomes small as shown in FIG. 3, and the coil becomes loosely wound, making it easy for telescoping to occur.

Therefore, in the present invention, as shown in FIG. 4, when the strip l passes through the hot run table 3, when the tail end of the strip passes through the section 11R9,
The lag rate after R2 is the lag rate I7 in section lIR+
．． Higher I7□ and further section If Il
When t is removed, the lag ratio after section 11113 is set to 3, which is higher than the lag ratio L2 in section 11R2, and the lag ratio is set to L4.t in stages for each section where the strip tail end is removed. L5. Let's gradually increase it to L6.

Here, to supplement how to determine the degree of increase in the lag rate between sections, the length of the tail end of the strip on the entry side of the i-th section IIR to the coiler 5 is P
, (mm), then the back tension Tl11 should be the same in every section, that is, the following (
2) Just select the lag rate that satisfies the equation.

T * l= lIX L +−−−−−−−−−−−
---------- As shown in (2), the back tensions T and l can be kept constant by increasing the lug ratio step by step as the tail end of the strip progresses. It is possible to prevent the occurrence.

〈Example〉 When winding up a strip with a standard of 5 PIID and a width of 1000 mm Thirty coils were wound with the indicated lag rates. The average yield after the coils were temper-rolled in a skin bath mill is shown in the same table.

For comparison, Table 1 also shows the results of a conventional example in which the lag rate of each section of the Bontran table was set to 30%.

Table 1 As is clear from this table, the yield after skin pass milling of the examples of the present invention is improved by 0.4% compared to the conventional examples. Furthermore, no scratches were observed in the coils of the present invention in the next step.

<Effects of the Invention> As explained above, according to the present invention, the lag ratio of each section of the hot run table roller is increased in stages according to the progress of the tail end of the strip. The tension can be kept constant, so the coil can be wound tightly.

As a result, it is possible to prevent scratches and scratches from occurring in the next process, and it is also possible to improve the yield of the product.

[Brief explanation of drawings]

Fig. 1 is a side view showing the arrangement of a hot rolling mill to which the present invention is applied, Fig. 2 is a characteristic diagram showing the speed pattern of the strip and pot run table roller circumferential speeds, and Fig. 3 is a conventional lug Fig. 4 is a characteristic diagram showing the relationship between the lag ratio and back tension according to the present invention. ... Hot run table roller 4... Vinci roll, 5... Coiler F1...
・First finishing stand F...Final finishing stand. 11R1 to 11R6...Hot run table roller section.

Claims (1)

[Claims] A method for winding a strip rolled in a continuous hot rolling mill onto a coiler through a hot run table where the strip is divided into a plurality of sections while applying a predetermined tension,
When the tail end of the strip leaves the final finishing stand of the hot rolling mill, the lag ratio L (%) of each section of the hot run table defined by the following formula is increased stepwise to A method for winding a strip in a continuous hot rolling mill characterized by maintaining a constant back tension at the tail end. L=(V_S-V_H_R/V_S)×100(%) where, V_S: Strip speed (m/min) V_H_R: Hot run table peripheral speed (m/min)