JPS63188424A - Top mark preventing method at strip winding time - Google Patents

Abstract

PURPOSE:To prevent the generation of the top mark of a strip by varying the retreating amt. of the pressing position of a wrapper roll and retreating timing according to the plate thickness of the strip. CONSTITUTION:When the tip of a strip 1 is passed through the position of the tip detector provided at the upper stream than a mandrel 2, the tip passing signal transmitted from the detector is taken into a wrapper roll control device 11. The tip position thereafter is subjected to tracking based on the rotation of a pinch roll 20 to decide the avoidance timing corresponding to the passing of wrapper rolls 31, 32, 33. The retreat amt. corresponding to the plate thickness is decided in a retreat amt. arithmetic unit 9. The correction amt. of the retreat timing taking into consideration the length of an inclined part is operated in a retreat timing arithmetic device 10. The found retreat amt. and retreat timing correction amt. are inputted into the wrapper roll control device 11, the retreat timing quickened by this retreat timing correction amt. to the retreat timing decided according to the passing of a step difference part and the retreat amt. are outputted to a hydraulic unit 12 to drive a hydraulic cylinder 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for preventing the occurrence of strip top marks in a down coiler of a hot strip mill.

[Conventional technology and its problems]

Winding in the down coiler of a hot strip mill is performed by winding the strip while pressing the strip against the mandrel using a rubber par roll after the tip of the strip is wound around the mandrel with a predetermined pressing force. For this reason, as shown in FIG.
A flaw called a top mark occurs due to the impactful contact that occurs when the wrapper roll passes through the wrapper roll. This top mark continues over a considerable number of turns from the innermost diameter portion of the coil, resulting in a decrease in yield.

As a means to solve such problems, Japanese Patent Laid-Open No. 57-2
In No. 02921, as shown in Fig. 4, the pressing positions of the wrapper rolls (31), (32), and (33) can be moved forward and backward by the wrapper roll arm (4) and the hydraulic cylinder (6), and An FFTA has been disclosed that prevents the occurrence of top marks by retracting the pressing position of the wrapper roll according to the thickness of the sheet as it passes.

By winding using this device, the above-mentioned top mark is considerably improved, but a sufficient effect has not yet been obtained. The reason for this is the retirement of the rapper role.
This is because only the thickness of the strip and the operating speed of the hydraulic cylinder (6) are considered for the roofing, so the avoidance timing is determined so that the amount of retraction of the wrapper roll at the tip of the strip is maximized. .

However, in reality, as shown in Figure 6, the shape of the stepped portion from the second roll onwards develops a sloped area that is influenced by the tip of the strip, so the pressure is not applied until this area contacts the Rubpur roll. If this is done, even if the wrapper roll is retracted at the tip of the strip, the above-mentioned top mark due to the inclined portion will still occur from the second roll onwards.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for always obtaining the fastest wrapper roll retraction timing even when the thickness of the strip wound on the down coiler changes. .

[Means for solving problems]

The present invention provides a method for preventing the occurrence of top marks on the strip by retracting the pressing position of the wrapper roll when the leading end of the strip wound around a down coiler passes. This method prevents the occurrence of top marks on the strip by changing the thickness according to the thickness.

[Action of the invention]

According to the method of the present invention, by changing the retraction amount and retraction timing of the wrapper roll according to the thickness of the strip to be wound on the down coiler, the optimal pressing position can always be obtained, and the slope caused by the step at the tip of the strip can be avoided. In order to retract the pressing position of the wrapper roll according to the passage of the wrapper roll, the retraction timing of the wrapper roll is earlier than when retracting only considering the step at the tip of the strip, thereby preventing the occurrence of top marks. can do.

〔Example〕

Next, embodiments of the present invention will be described in detail using the accompanying drawings. FIG. 1 is a diagram schematically showing a configuration for carrying out the present invention, in which (1) is a strip, (2) is a down coiler mandrel, (31), (32), and (33) is a strip (1). ) to press the mandrel ■, (A) is supported by the fulcrum ■, and the hydraulic cylinder (6
) and the wrapper roll (3
(8) is the fulcrum of the hydraulic cylinder (6); (9) is the fulcrum of the hydraulic cylinder (6);
) is a wrapper roll (
3]), (32), and (33) retraction a amount calculation device that corrects the pressing position! , 01 is a retraction timing calculation device that similarly corrects the retraction timing of the rub par rolls (31), (32), and (33) according to the plate thickness, and Ql) is the retraction amount calculation device (9) and the retraction timing. A wrapper roll flil m B 71, Q? that controls the pressing position of the wrapper roll based on the calculation result from the calculation device Ql.
) is a hydraulic unit that drives a hydraulic cylinder (6) based on the output from the rough bar roll control EQD. In addition, although only the love par roll (31) was illustrated in the above description, the same process is performed for the wrapper rolls (32) and (33).

Next, control of the pressing position of the wrapper roll with the above configuration will be explained. First, when the tip of the strip (!) passes through a tip detector (not shown) installed upstream of the mandrel ■, the tip passage signal from the detector is taken into the rough bar roll control side ID, and from then on The position of the tip of the wrapper roll (31) is tracked based on the rotation of the ball/chael (3).

The avoidance timing is determined according to the passage of (32) and (33).

By the way, as mentioned above, this retracting operation depends on the thickness of the plate. ! It is necessary to correct the amount and evacuation timing. Therefore, first, the retraction amount calculation device (9) calculates the retraction i! based on the relationship shown in FIG. Determine the amount. In FIG. 2, gland A is a barb whose retraction amount is given a bias value.

The purpose of assigning this bias value is that when the plate thickness is thin, the rolling speed usually increases, so the winding speed increases, and the tracking error at the stepped portion cannot be ignored, so it is necessary to take this error into consideration. This is because However, the amount of retraction may be determined without considering the bias value, as in BIIit.

Next, the evacuation timing calculation device (to) calculates the amount of correction of the evacuation timing in consideration of the length of the slope shown in FIG. 6, based on the relationship shown in Figure *3. In FIG. 3, CIa has a constant retraction timing correction amount for plate thicknesses of 2.0 mm or less, and Dlil has a bias value. As with the fi2 diagram, this vertical line is also based on the consideration of tracking errors due to an increase in winding speed when the plate thickness is thin. Also, the reason why the correction amount is kept constant for plate thicknesses of 201 mm or more is because for plate thicknesses larger than this, even if the tracking timing correction is accelerated, it will not be very effective (the coil winding appearance will only deteriorate, so This is due to the fact that no correction is made.

The evacuation amount and evacuation timing correction amount obtained in this way are input to the wrapper roll control device qD, and the evacuation timing determined according to the passage of the stepped portion is advanced by this evacuation timing correction amount i! i! ! The timing and retraction amount are output to the hydraulic unit a'3 to drive the hydraulic cylinder (6). Although the retraction timing and the retraction timing correction amount in the above explanation are values converted to the length on the rotational circumference of the coil stepped portion, they may be calculated separately using the rotational angle.

In this way, by driving the hydraulic cylinder (6) and controlling the pressing positions of the wrapper rolls (31), (32), and (33), it is possible to eliminate the impact caused by the step passing through each wrapper roll. The occurrence of top marks can be prevented without causing loosening of the winding.

Next, the effects when the method of the present invention is applied to an actual machine will be explained. First, the plate thickness: 5 to 12 m was obtained using the conventional method without using the method of the present invention and without controlling the retraction of the wrapper roll.
m1 provisional width: 918-1.2501. 10 strips of
0 coils were wound. The average depth of the top mark in this case was α48 Dragon.

On the other hand, the wrapper roll step i! A121 in FIG. 2 and D! in FIG. 3 are corrected for the amount and step avoidance timing, respectively. When the method of the present invention carried out according to the relationship shown in a was carried out under similar conditions, the average depth of the top mark could be significantly reduced to α13 - compared with the conventional method.

〔Effect of the invention〕

As described above, according to the method of the present invention, the pressing position of the wrapper roll can be controlled when the wrapper roll passes through the stepped portion with an appropriate amount of retraction and retraction timing that takes into account the sloped portion near the stepped portion depending on the thickness of the strip. As a result, the occurrence of top marks can be prevented to a minimum.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the tooth according to the present invention, and FIG. 2 is a schematic diagram showing the tooth of the present invention. Fig. 3 is a graph showing the relationship between the retraction timing correction amount and plate thickness of the present invention, Fig. fi4 is a diagram showing the outline of the down coiler, and Fig. 6 is the top mark generation mechanism. FIG. 6 is an explanatory diagram of the inclined portion near the stepped portion. l... Strip 2... Mandrel 31.
32.33...Rapper roll...Rabper roll arm 6...Hydraulic cylinder 5.8...Fully point 7...Ropdo 9...Retraction amount/ill calculation device! 0・
・・Evacuation timing calculation device ・・Rapper roll control device 12 ・・Hydraulic unit 2nd drawing Plate thickness (Third drawing 3rd plate thickness Cm)

Claims (1)

[Claims] In a method for preventing the occurrence of top marks on the strip by retracting the pressing position of the wrapper roll when the tip of the strip wound around the down coiler passes, the retracting amount and retracting timing of the pressing position are adjusted according to the thickness of the strip. A method for preventing top marks when winding a strip, characterized by varying the