JPH04138802A - Hot rolling method - Google Patents

Abstract

PURPOSE:To always keep the tension of strip on the outlet side of the final rolling mill constant and to manufacture a hot rolled steel sheet for deep drawing by strongly lubricating rolling by arranging a pinch roll just near the outlet side of the final rolling mill and executing strong lubrication of the final rolling mill at the same time of biting the strip on the outlet side of rolling mill with the pinch roll. CONSTITUTION:A sheet bar which is rolled with a roughing mill is strongly lubricating rolled with a hot rolling equipment. At this time, the tension of the strip on the outlet side of the rolling mill is always kept constant with the pinch roll 2. The pinch roll 2 is incorporated in the housing of the final rolling mill so as to be situated just near the final rolling mill. Therefore, the distance between the final rolling mill and the pinch roll 2 is very short and unsteady parts in the tip and rear end parts of coil when strongly lubricating rolling are very short.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a hot rolling method for stably manufacturing thin steel sheets for hot processing.

[Prior Art] In recent years, with the aim of reducing the cost of thin steel sheets for dry drawing, the development of hot-rolled steel sheets that have the same deep drawability as cold-rolled steel sheets in a hot rolling process has been studied. However, since highly lubricated rolling is essential for the development of these hot-rolled steel sheets for deep drawing, current hot strip mills have operational difficulties such as strip slippage.

On the other hand, endless rolling has been proposed in which the raw materials are connected at the entrance of the rolling mill and rolled without a joint U.

According to this method, it is possible to perform rolling with constant tension applied to the tube, making it possible to perform highly lubricated rolling and to produce hot-rolled steel sheets for deep drawing. In addition, when the coiler reaches a predetermined size, the strip is cut in front of the coiler, and the following strip is cut off at the end of the final stage of the Houtstononop mill until winding is started by the next coiler. It is not possible to apply tension to the sides. Therefore, during this period, strong lubrication rolling becomes impossible, and a large number of defective products are forced to be produced.

A technique has been disclosed in which a tensioning device is installed near the exit side of the final rolling mill of a hot strip mill. For example, JP-A-6
No. 0-44106 discloses a technique in which a tension applying device is installed near the exit side of the final rolling mill to constantly apply tension to the strip on the exit side of the rolling mill. However, this conventional technology requires a long distance between the final rolling mill and the tensioning device.
After all, it is impossible to perform highly lubricated rolling uniformly in the longitudinal direction of the strip, and it is inevitable to produce defective products in which non-lubricated rolled portions are mixed at the leading and trailing ends of the coil.

Furthermore, there is no suggestion whatsoever regarding strip slip prevention and operability during highly lubricated rolling.

[Problem to be Solved by the Invention 1] The present invention solves the above-mentioned problems, and by arranging pinch rolls immediately adjacent to the exit side of the final rolling mill, the tension of the strip on the exit side of the final rolling mill can be kept constant at all times. It is an object of the present invention to provide a hot rolling method for manufacturing hot rolled steel sheets for deep drawing by highly lubricated rolling.

[Means for Solving the Problems 1] As a result of extensive research, the present inventors have discovered an inter-rolling method that can uniformly perform highly lubricated rolling in the longitudinal direction of the slip.

The present invention solves the above-mentioned problem, and when a high-temperature material is thin-rolled using a plurality of rolling mills arranged in tandem, a pinch roll is disposed close to the exit side of the final rolling mill, and the rolling surface of the pinch roll is This is a hot rolling method characterized by strongly lubricating the final rolling mill simultaneously with biting of the output strip.

In the present invention, the immediate vicinity of the exit side means within 10 m from the center of the final rolling mill roll.

The present invention can also be applied to the case where high-temperature materials are connected to perform endless rolling.

[Effect] Hereinafter, the operation of the present invention will be explained in detail.

(1) Final pinch roll The pinch roll closest to the exit side of the rolling mill is the most important in the present invention, and by controlling the pinch roll, it is possible to keep the tension of the strip on the exit side of the rolling mill constant at all times. The distance between the pinch rolls and the final rolling mill shall be the closest.

By keeping the distance between the pinch rolls and the final rolling mill close, it is possible to reduce tension fluctuations when shearing the strip. This distance is within 10 m, preferably within 5 m, and 10 m or more. In this case, a defective portion occurs at the leading end of the strip.Another effective method is to incorporate pinch rolls into the housing of the final rolling mill.

The pinch roll diameter and its mm are not very important in the present invention. Also, is the tension of the strip on the exit side of the final rolling mill 1 kgf/mrr? or more is suitable, 3 kg f /
It is preferable that m is greater than or equal to m.

Note that during rolling with strong lubrication, it is necessary to synchronize the pinch rolls with the lubrication. In other words, by applying strong lubrication at the time when the strip on the exit side of the rolling mill is bitten by the pinch rolls, troubles such as slipping can be prevented, and rolling with strong lubrication can be carried out almost uniformly in the longitudinal direction of the slip, improving deep drawability. It also becomes possible to manufacture excellent hot rolled steel sheets.

Furthermore, even during endless hot rolling, there is no tension variation when shearing the strip, and a uniform coiler shape can be obtained.

(2) Strongly lubricated rolling Strongly lubricated rolling is important in the present invention and essential for the development of hot rolled steel sheets for deep drawing. In the present invention, highly lubricated rolling means that at least the final stand has a friction coefficient of 02.
It means rolling at 5 or less.

Suitable lubricants include ordinary oil lubricants, solid lubricants, and grease-based lubricants.

(3) Rolling Mill The structure, number of stands, distance between stands, and roll diameter of the rolling mill used in the present invention may be conventional. Small diameter rolls are suitable for reducing the rolling load and improving the cross-sectional shape of the steel plate.

(4) Sheet bar joining When performing endless rolling, it is necessary to connect the sheet bars at the entrance side of the rolling machine. An induction heating method or the like is suitable for connecting the seat bar.

(5) When endless rolling is performed, it is necessary to continuously wind the strip using a coiler. The coiler is wound and cut using conventional methods.

[Example] An example of the present invention will be described based on the drawings. FIG. 1 is a side view of a first embodiment of a hot rolling apparatus that can suitably carry out the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is a side view of the final rolling mill of FIG. 1. be.

1 is a hot strip mill, 2 is a pinch roll, and 3 is a lubrication equipment. Plate thickness 10-30 manufactured by rough rolling mill
mm sheet bar is rolled with strong lubrication in a hot rolling facility. At this time, the tension of the strip on the exit side of the rolling mill is always kept constant by the pinch rolls 2. The tension of the strip on the exit side of the rolling mill can be controlled to 3 to 10 kgf/mrn. As shown in FIG.
is incorporated into the final rolling mill housing 10 so as to be located in close proximity to the final rolling mill. Therefore, the distance between the final rolling mill and the pinch rolls 2 is extremely short, and the unsteady portion at the leading and trailing ends of the coil during highly lubricated rolling is extremely short.

FIG. 4 is a side view of the second embodiment of the hot rolling apparatus, and FIG. 5 is a plan view of FIG. 4. 4 is a Zi-Dopa joining machine, 5 is a hot strip mill, 6 is a pinch roll, 7 is a lubrication equipment,
8 is a shearing machine, and 9 is a carp. Sheet bars with a thickness of 10 to 30 mm manufactured by a rough rolling mill are connected by a sheet bar connecting machine and continuously rolled with strong lubrication in a hot rolling facility. At this time, the tension of the strip on the exit side of the rolling mill is always kept constant by the pinch rolls 6. The tension of the strip on the exit side of the rolling mill can be controlled to 3~lokgf/mrn''. The rolled strip is continuously sheared by a shearer 8 and then wound by a coiler 9. In this embodiment, a pinch By controlling the tension of the strip on the exit side by the rolls 6, the unsteady part during strip shearing and even during highly lubricated rolling can be significantly reduced, and a uniform material quality can be obtained in the longitudinal direction of the slip.

[Effect of the invention 1] As is clear from the above explanation, according to the present invention, it is possible to perform highly lubricated rolling uniformly in the longitudinal direction of the slip, and the unsteady portion at the tip and rear end of the coil can be significantly reduced. Not only is energy saving, resource saving and high productivity achieved,
It is now possible to manufacture hot-rolled steel sheets for deep drawing by highly lubricated rolling, which has a great effect.

[Brief explanation of the drawing]

FIG. 1 is a side view of a first embodiment of a hot rolling mill that can suitably carry out the present invention, FIG. 2 is a plan view of FIG. 1, and FIG.
FIG. 3 is a detailed side view of the final rolling mill shown in the figure; FIG. 4 is a front view of a second embodiment of hot rolling equipment that can suitably carry out the present invention;
FIG. 5 is a plan view of FIG. 4.

Claims (1)

[Scope of Claims] 1. When a high-temperature material is rolled to reduce its thickness using a plurality of rolling mills arranged in tandem, a pinch roll is arranged close to the exit side of the final rolling mill, and a pinch roll is placed on the exit side of the rolling mill. A hot rolling method characterized by strongly lubricating the final rolling mill at the same time as strip biting. 2.Claim 1, in which high-temperature materials are connected and endlessly rolled.
The hot rolling method described.