JPH0976012A - Method for coiling steel strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent defects in shape at an early stage of coiling by mounting a sleeve in the middle part in the width direction of a tension reel and coiling a steel strip. SOLUTION: For example, by mounting the sleeve 5 of 5-30mm in thick in the position of 30-90% of the middle part in the width direction of the steel strip to be coiled with the tension reel (mandrel) 2, the steel strip is coiled as a coil 3. At the time of drawing out the coil 3, because the sleeve 5 is hardly contracted even when the mandrel of the tension reel 2 is contracted, the inside surface of the coil 3 is supported. So, the total of the amount of compressive strain and permanent strain are enough small, thus the change of the strain amount in the width direction of the steel strip also becomes small and the defects in shape (edge wave) at the early stage 4 of coiling of the steel strip around the tension reel 2 are prevented. In this way, the quality is improved as maintaining high productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel strip winding method.

[0002]

2. Description of the Related Art Steel strips after temper rolling, steel strips that have been subjected to temper rolling after heat treatment in a continuous annealing facility, and steel strips that have been subjected to a tension leveler to correct the shape (hereinafter referred to as "steel strips after shape correction") Is a predetermined amount wound on a tension reel to form a steel strip coil, and this steel strip coil is extracted from the tension reel and supplied to the coil rewind reel on the processing line entry side of the next process or the customer's plating process, molding process, etc. It is a thing. Since the steel strip coil is pulled out from the tension reel in this way, the core of the tension reel, that is, the mandrel, can be enlarged or reduced in diameter, and when it is enlarged, it is made into a perfect circle so that the shape-corrected steel strip has a predetermined amount. Winding and then reducing the mandrel diameter to extract the steel strip coil.The mandrel surface is as close to a perfect circle as possible from the viewpoints of preventing the coil from collapsing after extraction and preventing the steel strip from being damaged. While making it cylindrical,
The mandrel diameter is set so that the steel strip does not yield so that the steel strip does not have a strong curl. Furthermore, since the tension reel applies a tension to the steel strip and winds it into a coil, a strong winding tightening force is applied to the inner diameter portion of the coil, so the mandrel is designed and manufactured so that deformation is minimized.

[0003]

However, as shown in FIG. 2, when a steel strip 1 having a shape-corrected plate thickness of 0.1 to 1.0 mm is wound on a tension reel 2 to form a steel strip coil 3, the initial winding stage is as follows. The width direction both ends of the steel strip 1 of 4 (5 to 50 mm thick portion from the set diameter of the tension reel mandrel diameter, 50 to 500 m length from the winding end of the tension reel at the steel strip length) are in the longitudinal direction of the steel strip. There is a problem in that a shape defect of waving (generally called an ear wave) occurs, the quality is remarkably impaired, and the yield is significantly reduced.
The method of the present invention has been made in order to advantageously solve such a problem, and an object thereof is to provide a steel strip winding method after shape correction, which hardly causes seismic wave shape defects. is there.

[0004]

A feature of the present invention is that when a shape-corrected steel strip is wound on a tension reel, a sleeve is attached to the center of the tension reel in the width direction to wind the steel strip. It is a steel strip winding method characterized by taking.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Generally, in a steel strip processing line such as plating equipment for treating steel strip, coil preparation equipment, tension leveler equipment for shape correction, temper rolling equipment, etc. The diameter of the roll is larger than the yield curvature so that the steel strip passing through the line is not plastically deformed by bending deformation of these rolls. Curvature coefficient β
Is defined as β = hE / DY (1) using the plate thickness h, the elastic modulus E, the diameter D of the rolls, and the yield stress of the steel strip as Y. If
It is general to set a large-diameter roll diameter such that β <0.5, depending on the conditions of the plate thickness and the steel strip material.

However, according to the result of analysis by the present inventors, the cause of the shape defect of the steel strip is as follows.
When winding on a tension reel that should not be plastically deformed, not only the bending stress due to the winding of the steel strip on the tension reel, but also the circumferential compressive stress of the steel strip due to the tightening due to winding and the It was found that this is due to plastic deformation of the steel strip due to residual stress. Further, conventionally, since the circumferential compressive stress of the steel strip due to the tightening of the steel strip coil, the residual stress of the steel strip, etc. were not sufficiently taken into consideration, the deformation behavior of the steel strip on the tension reel could not be fully grasped. I also found out.
When the steel strip after shape correction is wound on a tension reel, the steel strip is wound in the initial stage (winding thickness 5 to 50 mm,
Tensile stress equal to the winding tension is applied to the steel strip (50 to 500 m from the winding tip), but as the number of windings increases, the compressive stress in the circumferential direction of the steel strip due to the tightening of the winding from the outer circumference of the coil. As a result, the tension reel mandrel around which the steel strip is wound is strongly compressed in the initial stage of winding, and the tension reel mandrel contracts due to elastic deformation to reduce the diameter, thereby reducing the inner diameter of the coil. Further, when the coil is pulled out from the tension reel mandrel, the mandrel cannot support the inner diameter surface of the coil, so that the inner diameter is reduced.
Along with that, compressive strain is applied to the steel strip in the early stage of winding. That is, the steel strip in the initial winding stage is in a deformed state of compression bending in the longitudinal direction of the steel strip. When this compressive strain exceeds the yield strain (elastic limit strain) of the steel strip, the steel strip is plastically deformed and the length of the steel strip is slightly shortened.

However, in general, a steel strip is formed with a plate crown in the widthwise direction of the steel strip (the center portion in the widthwise direction of the strip is slightly thicker and both ends are slightly thinner). Since the force that compresses the initial portion of the winding in the central portion in the width direction is large, this compressive strain also becomes larger in the central portion in the width direction, and the steel strip length in the central portion in the width direction becomes shorter. Also, even if a steel strip with no plate crown and a uniform plate thickness in the width direction is wound around the tension reel and a uniform compression force is applied to the mandrel, the theory of material mechanics suggests that the central part of the plate width direction is more than the end part. It can be seen that the deformation of the mandrel is larger. That is, in the coil wound on the tension reel, when the coil inner diameter portion is deformed by the winding tightening force, the width center portion of the steel strip tends to be shortened. That is, for the steel strip, the central portion in the width direction is short, and when the coil is rewound to remove the restraint of the steel strip, the end portion of the steel strip becomes relatively long. That is, this appears as a defective shape of the ear wave.

Further, the inventors of the present invention mechanically examined the deformed state of the steel strip in winding the tension reel of the steel strip. As a result, the diameter of the tension reel was Dr (mm), and the reduction amount of the reel mandrel diameter caused by the winding. Is ΔD1, the strain amount εc1 of compression of the steel strip near the inner diameter of the coil caused by the reel mandrel deformation is approximately Dr.
Therefore, εc1 = ΔD1 / Dr (2). (Here, the signs of compressive stress and compressive strain are defined as positive.) Next, in order to remove this wound steel strip coil from the tension reel, when the mandrel is contracted, the winding tightening from the outer circumference of the coil has been caused until now. Since the resistance of the mandrel supporting the circumferential compressive stress of the steel strip disappears, the steel strip near the inner diameter of the coil is compressed and further contracted by ΔD2 in diameter. Since the diameter in the vicinity of the inner diameter portion can be regarded as substantially Dr, the compression strain Δε2 at that time is εc2 = ΔD2 / Dr (3). The total compression strain εc1 + εc2 was large in the widthwise central part, and a measurement result was obtained that was a fraction of the widthwise central part at the plate edge. The bending strain εb of the steel strip in the initial stage of winding the steel strip wound on the tension reel is determined as εb = h / Dr (4) from the plate thickness h and the reel diameter Dr, and the surface layer of the steel strip on the reel side is compressed. Strain, tensile strain is applied to the surface layer on the opposite side. This strain is almost constant in the width direction of the steel strip. On the other hand, the result of detailed measurement of the distribution of the residual stress in the longitudinal direction of the thin steel strip that has undergone shape correction at the plate thickness position shows that there is a compressive residual stress in the surface layer of the steel strip.
There is tensile residual stress in the center of the steel strip thickness. Assuming that the compressive residual stress of this steel strip surface layer is σs (here, the sign of the compressive stress is defined as positive), the residual strain εs of the steel strip surface layer due to this residual stress σs is given by εs = σs / E (5) Therefore, the total strain introduced to the reel side surface layer of the wound steel strip is εc1
+ Εc2 + εb + εs. Yield strain of steel strip εe
Is εe = Y / E (6) from the yield stress Y of the steel strip and the elastic modulus E. Therefore, if the sum of various compressive strains applied to the steel strip at the initial stage of winding the steel strip is larger than εe, The strip is plastically deformed, and the permanent strain εp (the steel strip becomes shorter in the longitudinal direction) remains as in the following formula. [epsilon] p = ([epsilon] c1 + [epsilon] c2 + [epsilon] b + [epsilon] s)-[epsilon] e (7) The shape defect of the coil inner diameter portion at the time of winding the steel strip, which is to be solved by the method of the present invention, is expressed by the formula (7).
The condition is> 0, and the steel strip has a large central portion in the width direction and a small end portion in the width direction of the steel strip, so that it appears as a wave.

Winding steel strip A defective shape occurs only in the steel strip in the initial winding stage (winding thickness 5 to 50 mm, 5 to 500 m from the winding tip) because the steel strip itself wound in the initial stage of winding is , In order to support the coil outer peripheral portion against the winding tightening force, on the outer peripheral side of the steel strip coil, the total of the compressive strains of the above formula (3) becomes small, and the bending strain of the formula (4) is also the plate thickness of the steel strip. Since it is the ratio of the bending diameter and the bending diameter, it becomes smaller as the diameter increases with winding on the outer diameter side of the steel coil.
This is because the condition of εp <0 in Expression (7), that is, the elastic deformation region is easily entered. Further, in reality, even if there is a permanent strain, if it is small, it is rare that the outer circumference of the steel strip wound around the coil does not appear as a poor shape and the outer circumference of the steel strip is defective.

Therefore, according to the equation (7) representing the plastic strain generated in the winding, in order to prevent the defective shape, εp≤0, and the entire width and the entire length of the steel strip are kept in the elastic deformation region. , Εp> 0, εp
Is sufficiently small, it does not result in a defective shape in which an ear wave is generated. The condition of εp ≦ 0 is that if a steel strip with a large yield stress, that is, a steel strip that is hard and difficult to deform, is selected, εe will increase as shown in equation (6) and it will be easy to achieve it, but the yield stress will be It is determined by the steel strip application and cannot be changed by the manufacturer. Further, in order to reduce the compressive strain εc1 of the formula (2), a method of winding on a tension reel having strong rigidity to withstand a winding tightening force due to winding tension can be considered, but in reality, the rolled steel strip is used. If the reel diameter is reduced when the coil is pulled out from the tension reel, the rigidity of the steel strip alone cannot withstand the winding tightening force. It will be bigger than when. That is, εc1 + εc2 does not change much, and the effectiveness is considerably reduced.

Therefore, in the method of the present invention, in order to satisfy the condition of εp ≦ 0 in the above formula (7) or to make εp sufficiently small, the circumference of the steel strip due to the coil winding tightening of the formula (2). The inventors have found a method for reducing the amount of compressive strain εc1 due to the directional compressive stress and the amount of compressive strain εc2 due to the reduction of the mandrel diameter of the equation (3). That is, before winding the steel strip on the tension reel, a sleeve is attached to the central portion in the width direction of the tension reel, and then the steel strip is wound on the coil, whereby the rigidity of the winding core against tightening of the coil is reduced by the sleeve. Going up
The reduction amount ΔD1 of the coil inner diameter due to the winding tightening force becomes smaller, and as a result, εc1 becomes smaller from the equation (1). Furthermore, even if the mandrel diameter is reduced in order to remove the coil from the mandrel, the sleeve hardly shrinks,
The inner diameter of the coil can be supported, and the reduction amount ΔD2 of the coil inner diameter when the mandrel diameter is reduced becomes extremely small. As a result, the compressive strain amount εc2 of the steel strip becomes extremely small according to the equation (2). At this time, the compressive strain amounts εc1 and ε
The reduction amount of c2 is influenced by the rigidity and thickness of the sleeve. According to the results of various studies by the present inventors, 6 × 10 ⁴
If the longitudinal elastic modulus in the circumferential direction is MPa or more and the sleeve thickness is 5 mm or more, the total compressive strain amount of εc1 and εc2 is 0.
It is possible to reduce 0004 to 0.0012, and it is possible to significantly improve the defective shape. Further, if the rigidity of the sleeve is too high, the sleeve becomes brittle and cracks easily occur due to impact or the like, so that it is practically preferable that the longitudinal elastic modulus of the sleeve is 40 × 10 ⁴ MPa or less. Further, 30 mm is sufficient as the upper limit of the thickness.

[0012] However, the commonly used inner diameter sleeve for preventing the coil collapse is for the purpose of preventing the coil collapse and it is advantageous that it is light in terms of handling. A thin sleeve of 4 mm or a sleeve made of paper and having a thickness of 10 to 20 mm is used. However, even if such a sleeve is used for preventing a defective shape which is a target of the method of the present invention, the rigidity and the thickness are not sufficient. It is impossible to prevent the defective shape in the initial stage of winding. Further, since the amount of compressive strain at the time of winding the coil is large in the central portion in the width direction of the steel strip as described above, 30 to 90% of the central portion in the width direction of the steel strip is provided by the sleeve as described above.
It is possible to surely prevent the defective shape by supporting, for example, in the case of winding a thin steel strip with a width of 700 to 1100 mm, the length is 600 mm and the thickness is 10 m.
By using a steel sleeve having a diameter of m and an inner diameter of 500 mm, it is possible to reliably prevent the defective shape of the steel strip in the initial stage of winding and reduce the weight of the sleeve. Further, the device for handling the sleeve can be downsized, and the weight can be reduced to about 30% or less by constructing the sleeve from a carbon fiber composite material or the like. As the material of the sleeve, steel such as the above, carbon fiber composite material, copper, titanium, aluminum, etc.,
These alloys, ceramic materials, and combinations of these materials or combinations of these materials and resin materials can be used.

Next, the method of the present invention will be described with reference to the drawings. In FIG. 1, a sleeve 5 of 5 to 30 mm is mounted on the tension reel (mandrel) 2 at a position of 30 to 90% of the center of the winding steel strip in the width direction, and the steel strip is wound as a coil 3 and wound. , When pulling out the coil 3 from the tension reel 2 mandrel, the sleeve 5 is removed even if the mandrel of the tension reel 2 is reduced.
Since the inner surface of the coil 3 can be supported, the total amount of compressive strain and the permanent strain as described above are sufficiently small. Therefore, the change in strain in the width direction of the steel strip is also small, and the tension The purpose of the present invention is to prevent a defective shape (ear wave) in the initial stage 4 of winding the steel strip on the reel 2 (winding thickness 5 to 50 mm, 50 to 500 m from the tip of the winding steel strip).

Next, examples of the method of the present invention will be given together with comparative examples.

[Table 1]

[0015]

[Table 2] Note 1: Steel strip composition wt%, C: 0.04 to 0.12, Mn: 0.30 to
0.45, Si: 0.005, P: 0.015 to 0.025, S: 0.010 to 0.020
, Sol.Al: 0.01, i: trace, Nb: trace, residual steel strip thickness consisting of Fe and impurities 0.18 to 0.90 mm, steel strip width 715 to 1200 mm
The cold-rolled steel strip of No. 1 was used as an original plate, annealed so as to have a temper degree of T4 to T5, and then subjected to temper rolling at a rolling reduction of 1.5 to 2.0%. Then, winding on the tension reel is 20
The average winding speed is 400-600m /
It took about 15 t coil in minutes. Note 2: For the steel strip shape correction, the one denoted by SP indicates a steel strip wound after temper rolling, and the steel strip subjected to shape correction by the tension leveler after temper rolling is denoted as TL. Note 3: Steel strip seismic waves are evaluated by cutting the steel strip in the initial stage of winding the strip (200 m from the winding tip) every 2 m and placing it on a horizontal surface plate, and the wave height at the end of the strip is 1.5 mm. Small ear wave generation less than, medium wave height of 1.5-3.0 mm,
The wave height of 3.0 to 4.5 mm is large, and the wave height of more than 4.5 mm is extra large. If the ear wave is small, it will pass in most applications. In the case of ear wave, it fails in severe applications, and in the case of ear wave, it fails in all applications.

[0016]

EFFECTS OF THE INVENTION According to the method of the present invention, it is possible to reliably prevent shape defects (ear waves, etc.) at the initial stage of winding, which occur during winding of the steel strip after the shape correction in temper rolling. The quality can be improved and the yield can be improved, and an extra step for discarding the defective shape portion is unnecessary. In addition, as a modification of the device, a fixed sleeve narrower than the steel strip width on the reel mandrel (removably designed)
Since it only needs to be covered, it is possible to prevent seismic waves at both ends of the steel strip at low cost. Further, since complicated control such as winding tension control is not required, it is possible to obtain an excellent effect such that the quality can be improved while maintaining the conventional high productivity.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an example of the method of the present invention.

FIG. 2 is a side view showing a conventional steel strip winding.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Imajo 5-3 Tokai-cho, Tokai-shi, Aichi Nippon Steel Co., Ltd. Nagoya Steel Works (72) Inventor Shinya Nakamura 5-Tokai-cho, Tokai-shi, Aichi 3 Inside Nippon Steel Works, Nippon Steel Co., Ltd.

Claims (2)

[Claims] 1. A method of winding a steel strip, comprising winding a steel strip after shape correction on a tension reel, by attaching a sleeve to the center of the tension reel in the width direction and winding the steel strip. 2. The steel strip winding according to claim 1, wherein the tension reel is fitted with a sleeve of 5 to 30 mm at 30 to 90% of the central portion in the widthwise direction of the steel strip, and the steel strip is wound up. Method.