JPH01104406A - Method for passing oiled steel plate in continuous mill - Google Patents

Abstract

PURPOSE:To execute a stabilized plate passing by preventing the slippage of an oiled steel plate without deteriorating the life of a bridle roll by pressing a snubber roll to a bridle roll by the pressure corresponding to the number of rotations of the bridle roll. CONSTITUTION:An oiled steel plate 1 is fed to a louver 5 via the bridle roll 4 arranged along a transfer line. A snubber roll 7 is confronted by interposing the steel plate 1 in the respective bridle roll 4. At the time when the number of rotations of the bridle roll 4 is few, the pressing force of the snubber roll 7 is increased and in case of its being many, the pressing force of the snubber roll 7 is decreased. The slippage of the steel plate 1 is prevented without deteriorating the durability of the bridle roll 4 and a stabilized plate passing can be thus performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for continuously feeding oil-coated steel sheets that are prone to slip into a cold rolling mill.゛[Prior art] As a method for cold rolling steel plates with high productivity,
Completely continuous cold rolling mills have come into use (The 1st Chugoku-Kyushu Joint Technical Conference sponsored by the Japan Society of Plastic Descending and others, December 12, 1980) (Refer to pages 1 to 11 of the ``Technology'' collection of papers).

This fully continuous cold rolling mill is equipped with a welder and a looper on the entrance side of the steel plate. Then, the coils automatically inserted into the two payoff reels provided on the entry side are sent out alternately, and by butt welding the rear end of the preceding steel plate and the tip of the following steel plate, the coils are connected to the preceding coil. Connections with subsequent coils are made. The looper absorbs the stoppage of the steel plate during welding, feeds the steel plate to the cold rolling mill without stopping, and performs cold rolling under stable conditions.

Incidentally, as a recent trend, the level of user demands regarding flaws in steel sheets has become extremely strict. This is because as a result of advances in processing technology, there are more opportunities to perform severe processing on steel plates. That is, when a steel plate is subjected to severe processing, minute flaws in the steel plate cause fatal defects such as cracks. One of the causes of such flaws is that the steel plates before cold rolling rub against each other or against the conveyor rolls, resulting in flaws. An effective measure to prevent this flaw is to run a steel plate coated with oil. The application of oil creates an oil film on the surface of the steel sheets, which prevents the steel sheets from coming into contact with each other or from coming into direct contact with the rolls.

[Problems to be solved by the invention] - On the other hand, in the steel plate conveyance line, the tension applied to the steel plate near the welding machine is zero to low tension, and the tension is slightly higher at the louver part, causing the cold rolling. The tension of the steel plate fed into the machine is increased to stabilize rolling conditions. In this way, when the tension differs along the conveyance line, the steel plate tends to slip on the peripheral surface of the feed roll provided on the conveyance path.

In particular, when an oiled steel plate is passed through, the coefficient of friction on the surface of the steel plate is significantly reduced, making it extremely slippery. So,
As a result, the speeds of the rolls and the steel plate do not match, causing problems such as poor tracking, tension fluctuations, scratches, and ash removal, making it difficult to thread the steel plate.

As a means to prevent the steel plate from slipping during this conveyance process, it is conceivable to provide a large number of bridle rolls with a large coefficient of friction along the conveyance line. However, increasing the number of bridle rolls increases equipment costs and is not a practical solution. It is also conceivable to increase the pressing force of a snubber roll facing the bridle roll to prevent the steel plate passing between the bridle roll and the snubber roll from slipping. However, if the pressing force of the snubber roll is simply increased, the durability of the corresponding bridle roll made of a material such as rubber will be degraded. In this regard, it is possible to use a highly durable steel roll as a bridle roll, but since the steel plate is prone to scratches when slipping occurs, such a roll cannot be used, and rubber rolls are generally used. has been done.

Therefore, an object of the present invention is to perform stable sheet threading by adjusting the pressing force of the snubber roll without deteriorating the life of the bridle roll (and preventing slippage of the oil-coated steel sheet).

[Means for solving problems]

In order to achieve the object, the sheet threading method of the present invention applies the oil to the bridle roll provided in the conveyance path of the oiled steel sheet in a continuous mill in which the oiled steel sheet is continuously introduced into a cold rolling mill. Snubber rolls are opposed to each other with a steel plate in between, and the pressing force of the snubber roll against the bridle roll is small when the bridle roll rotates at a high speed and increases when the bridle roll rotates at a low speed.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained using examples with reference to the drawings.

FIG. 1 shows a conveyance line for conveying a steel plate unwound from a coil to a cold rolling mill in this embodiment.

The steel plate 1 is unwound from the coils 2a and 2b and welded 8
Sent to 13th. The steel plate 1 used is one that has been pickled and then coated with pre-coat oil.

The steel plate 10 is unwound by alternating coils 2a using a payoff reel placed on the inlet side of the conveyance line.

This is done from 2b. After nii is completely fed out from the coil 2a and the tension becomes 0, the steel plate l is fed out from the other coil 2b, and the steel plate 1 is fed out from the coil 2b.
The tip end of the coil 2a is butt-welded to the rear end of the steel plate l from the coil 2a using a welding machine 3.

The steel plate l, which has been made continuous by welding the front and rear ends, passes through a bridle roll 4 arranged along a conveyance line and then passes through a looper 5.
sent to. This looper 5 is movable left and right in the drawing as shown by arrows. This movement makes the traveling speed of the steel plate 1 on the exit side of the louver 5 independent from the input side when the welding machine 3 welds the rear end of the preceding steel INI and the tip of the following steel plate I. That is, when the end of the steel plate 1 is welded, the movement of the steel plate 10 on the louver 5 side is interrupted, so the looper 5 is moved to the right side in the drawing, and the steel plate 1 within the moving range is cold rolled. Send it to machine 6. In addition, when moving the looper 5, it is preferable to apply a predetermined tension to the steel plate l. Then, after welding is completed, the louver 5 is sequentially moved to the left to ensure the amount of steel plate 1 to be fed out required for the next welding.

A snubber roll 7 is made to face each of the bridle rolls 4 provided on this conveyance line with the steel plate 1 interposed therebetween. These snubber rolls 7 are pressed against the bridle roll 4 with a predetermined pressure P. FIG. 2 is a graph showing the limit of the pressure P applied to the bridle roll 4 at this time.

As is clear from this figure, as the rotational speed of the bridle roll 4 increases, the pressure P at the service limit decreases. Therefore, in this embodiment, the pressure P of the snubber roll 7 is adjusted based on the curve showing this service life limit.

By the way, the steel plate 1 is threaded with a constant tension between the rolling mill 6 and the bridle roll 4, and with a different tension between the payoff reel 2 and the bridle roll 4.

In a steady state of high-speed sheet threading, no particular slippage problem occurs. However, the threading of one coil was completed and the steel plate 1
When the payoff reel 2 is removed from the payoff reel 2, the tension between the payoff reel 2 and the bridle roll 4 becomes 0,
A large tension step occurs before and after the bridle roll 4. Such a phenomenon occurs even when the tension between the payoff reel 2 and the bridle roll 4 becomes low, even if it does not become zero. In such a case, the greatest slippage occurs in the bridle roll 4. At this timing, the speed of the steel plate l is held down in order to stop the tail end of the coil by the welding machine, and the steel plate is threaded at a low speed.

Therefore, the present invention utilizes this timing. That is, when the rotational speed of the bridle roll 4 is low, the pressing force of the snubber roll 7 is set high, and when the rotational speed of the bridle roll 40 is high, the pressing force of the snubber roll 7 is set low. This not only prevents the durability of the bridle roll 4 from deteriorating, but also sufficiently prevents the steel plate l from slipping.

Note that a tension pad 9 with a tracking function is provided on the downstream side of the welding machine 3 on the conveyance line. This tension pad 9 clamps the rear end of the steel plate 1 based on a signal related to the signal state of the steel plate 1 sent from a pulse generator 8 attached to the bridle roll 4 or the like. This prevents the steel plate l from falling off from the bridle roll 4 after the bridle roll 4 has stopped.

If the above-mentioned slippage occurs in the bridle roll 4,
The tension pad 9 pinches the steel plate 1 from both sides to stop it. At this time, if the timing of the clamping by the tension pads 9 is off, the steel plate 1 may slip past the bridle roll 4 in some cases, and even in other cases, the steel plate 1 will not stop at a predetermined position. If such a tail drop occurs or the steel plate 1 stops at a shifted position, it is necessary to pull the steel plate 1 back to the normal stopping position within the welding machine 3. As a result, front handling time increases and productivity is hindered. Furthermore, if it takes a long time to pull back, the mill section is forced to stop, causing the gauge to come off. Therefore, in this embodiment, the tension pad 9 is installed in order to prevent such fall-off and positional displacement.
has a tracking function.

Further, the threading speed of the steel sheet 1 may be measured using a non-driven measuring roll 10 with low inertia. When such a measuring roll 10 is used, unlike the bridle roll 4 which is applied with rotational force by a motor, there is no slip between the measuring roll 10 and the steel plate 1, so that the sheet passing speed can be accurately detected. Therefore, it is also possible to calculate the number of rotations of the bridle roll 4 based on the sheet passing speed detected by the measuring roll 10, and to control the pressure P based on the result of this calculation.

In this way, the steel plate l can be processed without defects or productivity loss due to slipping during the conveyance line.
It is fed into a cold rolling mill 6 and wound up as a cold rolled coil 11 with stable and good surface properties.

〔Effect of the invention〕

As explained above, in the present invention, slipping of the oiled steel plate on the circumferential surface of the bridle roll is prevented by pressing the snubber roll against the bridle roll with a pressure corresponding to the rotation speed of the bridle roll. There is. Therefore, it becomes possible to feed the oiled steel sheet to the cold rolling mill without deteriorating the durability of the bridle roll, without surface defects caused by slippage, and without hindering productivity. Therefore, the surface properties of the cold-rolled product are excellent, and even if the product is subjected to strong processing such as deep drawing, defects such as holes and breakage will not occur.

[Brief explanation of the drawing]

FIG. 1 shows a conveyance line according to an embodiment of the present invention, and FIG. 2 is a graph showing the relationship between the number of rotations of the bridle roll and the limit pressure. Patent applicant: Nippon Steel Corporation Agent: Masu Tebori (and 2 others)

Claims (1)

[Claims] 1. In a continuous mill in which steel plates are continuously conveyed to a cold rolling mill, a snubber roll is opposed to a bridle roll provided on the conveyance path of the steel plate with the steel plate sandwiched therebetween, and the pressing force of the snubber roll against the bridle roll is A method for threading an oil-coated steel plate in a continuous mill, characterized in that the steel plate whose surface is coated with oil is passed through the steel plate by making it small when the bridle roll rotates at high speed and increasing when the bridle roll rotates at low speed.