JPH07236907A - Method for preventing happening of slip in continuous cold rolling of strip - Google Patents

Abstract

PURPOSE:To prevent the occurrence of cracking when a highly brittle material is passed through in a rolling method with continuous cold rolling mill having a slide preventing guide using of intermesh rolls. CONSTITUTION:In this rolling method of a strip of steel sheet, the slide preventing guide 2 having a structure that consists of plural rolls and the underside of at least one roll 21 is situated in the lower part of the pass plane is arranged on the inlet side of a 1st stand of the continuous cold rolling mill for strips which consists of plural stands. An intermesh amount control mechanism 4 is provided and the intermesh amount is changed in accordance with the changing part of the shape of the passing strip while maintaining the force of constraint to the passing strip below the critical buckling force by changing the intermesh amount for every material. Since the intermesh amount is adjusted in accordance with the changing part of the shape in a degree that the force of constraint below the backling of the rolling mill is not eliminated, sliding is prevented, also bending stress by the intermesh is reduced and breaking is prevented.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to strips, and in particular to
The present invention relates to prevention of sliding of a strip in continuous cold rolling of a strip of highly brittle material.

[0002]

2. Description of the Related Art Conventionally, when strip steel sheets are rolled by a continuous cold rolling mill, the occurrence of slides on the strips, particularly the slides on the first stand, is mostly due to local narrowing of the strips. This leads to breakage, and also damages the rolls of each stand on the downstream side, which requires a long time for this restoration, and the economic damage is great.

Therefore, a width setting guide is provided at the front position of the first stand of the continuous cold rolling mill, and the upper and lower parts of the width setting guide are restrained by the lumber to prevent the sliding in the width direction to prevent the slide from occurring. There is.

However, in this method, since the plate surface is constantly pressed from above and the plate and the wood are in contact with each other, debris from the barge and gouge defects of the plate adhere to the plate surface, which causes streaky defects in the rolling direction. Can occur, which is a problem as the required surface appearance becomes more stringent.

On the other hand, in order to improve the overall yield up to the final product, the so-called pickling note rim, which eliminates the ear trimming in the pickling process, is increasing, and the hot coil has poor width accuracy during cold rolling. To pass through
Since it is necessary to weaken the pressing of the width setting guide, the plate restraining force on the entrance side of the rolling mill becomes smaller, and the frequency of accidents associated with the occurrence of sliding increases.

For this reason, recently, in place of the conventional width setting guide for restraining the movement in the width direction, the lower surface of the fixed roll is arranged between the fixed rolls in which the upper surfaces of the plurality of rolls are arranged so as to coincide with the threading level. A guide with fixed intermesh rolls placed below the threading level was installed. This guide restrains the strip in the vertical direction and has no limitation in the width direction, so that there is an advantage that even a strip having a low width dimension can be stably passed.

In order to prevent the guides using the intermesh rolls from sliding on the first stand of the continuous cold rolling mill, it is necessary to increase the vertical restraining force of the strips by the intermesh rolls. The distance from the lower surface of the intermesh roll to the passage surface or below, that is, the amount of intermesh is considerably large.

Therefore, for highly brittle materials such as electromagnetic steel sheets,
When the guide using this intermesh roll is applied, there is a risk that repeated bending occurs in that portion and brittle fracture occurs. In particular, in a welded portion having a sharp shape change, the risk of causing brittle fracture is high due to stress concentration during repeated bending.

As a countermeasure against this, it is conceivable to replace the intermesh roll in such a guide device with a roll having a large roll diameter so that the bending stress becomes small during rolling with high brittleness, but it is inevitable to suspend rolling for the replacement. It is not realistic.

For this reason, in continuous cold rolling of brittle materials using this type of guide, it has been considered unavoidable to some extent to break due to brittleness in order to prevent slides from occurring.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to effectively prevent the occurrence of cracking of a strip in a highly brittle material in a rolling method by a continuous cold rolling mill having such a slide prevention guide by an intermesh roll. To provide the means.

[0012]

Conventionally, when a brittle material is rolled by a continuous cold rolling mill having such a slide-prevention guide, fracture of the welded portion is considered to be related to bending stress only to the bending ratio of the intermesh roll. However, the pushing amount below the threading level of the intermesh roll,
That is, it was completed based on the new finding that it has a direct relationship with the amount of intermesh.

That is, according to the present invention, a strip comprising a plurality of stands is provided with a plurality of rolls on the inlet side of the first stand of a continuous cold rolling mill, and the lower surface of at least one of the plurality of rolls is threaded. In the rolling method of strip steel sheet by a continuous cold rolling mill with a strip guide having a structure located below the surface, the inter-mesh amount of the roll is changed for each material and the strip strip is cut below the buckling limit force. The amount of intermesh of the intermesh roll of the plate passing guide is changed according to the changed portion of the form of the strip passing plate while maintaining the restraining force of No.

Needless to say, when changing the intermesh, it is important to tune the intermesh positions in the width direction on the drive side and the working side, and the intermesh change is performed in synchronization.

[0015]

The bending stress leading to rupture can be reduced by adjusting the pushing amount of the intermesh roll into the threading plate according to the portion where the shape is changed so that the restraining force of the strip threading plate is not lost. It is possible to prevent sliding when passing through the rolling mill, reduce bending stress due to the intermesh, and prevent breakage.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a system for intermesh amount control for implementing the present invention.

In the figure, reference numeral 1 is a continuous cold rolling mill comprising first to fifth stands, and a slide prevention having an intermesh roll 21 whose vertical movement amount is controlled is provided in front of the first stand. The guide 2 is provided, and the strip S is passed through the tension roll 3, constrained in the vertical direction by the intermesh roll of the guide 2, and rolled by the continuous cold rolling mill 1. Reference numeral 4 denotes a control mechanism that adjusts the movement amount of the intermesh roll 21 to control the intermesh amount.

The control mechanism 4 obtains information relating to the buckling limit value of the rolling stand depending on the type of material of the strip to be passed and welding point information for notifying the welding position of the strip to be passed, and from this, the intermesh amount is obtained. By the intermesh amount determining mechanism 41, a hydraulic control device 42 that controls the hydraulic circuit by a signal from the intermesh amount determining mechanism 41, and a signal from the hydraulic control device 42 that causes the intermesh roll to move vertically. Solenoid valve 44 for feeding pressurized oil to operating hydraulic device 43
Consists of.

FIG. 2 shows the relationship between the inter-mesh amount Hmm and bending stress σ _y input to the inter-mesh amount determining mechanism 41 after obtaining information on the welded portion of the threaded plate S in FIG. 1 above. , Σ _y is within the range of the intermesh amount X that does not exceed the critical value Y, the intermesh amount mm is controlled along the control curve A of the specific strip material so that the restraining force for preventing the sliding is passed. While being applied to the plate, a stress equal to or lower than the bending stress Y that causes cracks in the passing plate is applied.

The intermesh amount H in FIG.
In the guide 2 shown in FIG. 3, two fixed rolls 22 are arranged so that their upper surfaces are located at the threading level L.
Is an amount indicating the amount H of indentation of the inter-mesh roll 21 arranged in the middle of the level below the threading level L.

By controlling the intermesh amount H of the intermesh roll 21 within the breaking bending stress limit X based on FIG. 2, it is possible to control the occurrence of sliding of the threaded plate without causing stress fracture.

[0022]

The present invention has the following effects.

(1) In continuous cold rolling of a highly brittle metal plate such as an electromagnetic steel plate, it is possible to prevent sliding of the strip on the entry side of the first stand and to prevent the strip from breaking due to bending stress. You can

(2) To change the roll diameter of the roll type guide on the entry side of the first stand in continuous cold rolling of ordinary steel materials such as ordinary steel and highly brittle metal sheets such as electromagnetic steel sheets. In addition, it is possible to prevent sliding of the threaded plate on the entry side and also to prevent breakage of the threaded plate due to bending stress.

[Brief description of drawings]

FIG. 1 shows a control system for controlling the intermesh amount of an intermesh roll for carrying out the present invention.

FIG. 2 is a diagram showing a relationship between an intermesh amount and a stress bending amount leading to fracture when the threaded plate is a highly brittle material.

FIG. 3 shows a procedure for measuring the changed intermesh amount of an intermesh roll in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Continuous cold rolling mill 2 Slide prevention guide 21 Intermesh roll 3 Tension roll 4 Intermesh amount control mechanism 41 Intermesh amount determination mechanism 42 Hydraulic control device 43 Hydraulic device 44 Solenoid valve # 1-5 Roll stand

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kyutaka Uto 1-1 Tobahata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Shin Nippon Steel Co., Ltd. Yawata Works

Claims (1)

[Claims] 1. A continuous cold rolling mill for a strip comprising a plurality of stands, wherein the lower surface of at least one of the plurality of rolls is located below the passing surface of the first stand of the continuous cold rolling mill. In the method of rolling strip steel sheet by the continuous cold rolling mill with the strip guide having the structure located, the intermesh amount of the roll is changed for each material and the restraining force to the strip is set below the buckling limit force. A method for preventing slippage during continuous cold rolling of a strip, wherein the amount of intermesh of an intermesh roll of the sheet passing guide is changed according to a portion where the shape of the strip passing plate is changed.