JP3113801B2 - Winding method of steel strip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A steel strip after temper rolling, a steel strip subjected to temper rolling after heat treatment in a continuous annealing facility, and a steel strip subjected to a tension leveler for shape correction (hereinafter referred to as a steel strip after shape correction). Takes a predetermined amount on a tension reel to form a steel strip coil, removes the steel strip coil from the tension reel, and supplies the steel strip coil to a coil rewinding reel on a processing line entry side of a next step or a customer's plating step, forming step, etc. Things. In order to remove the steel strip coil from the tension reel in this way, the core of the tension reel, that is, the mandrel, can be enlarged or reduced in diameter, so that the steel strip after the shape correction is made a predetermined amount by making it a perfect circle when expanding. Winding, then reducing the diameter of the mandrel, and extracting the steel strip coil, from the viewpoint of preventing coil crushing after extraction and not giving a press flaw etc. to the mandrel surface as close as possible to a perfect circle While having a cylindrical shape,
The mandrel diameter is set so that the steel strip does not yield so that the steel strip does not have a strong winding habit. Further, since the tension reel applies a tension to the steel strip and winds the coil into a coil shape, a strong tightening force is applied to the inner diameter portion of the coil. Therefore, the mandrel is designed and manufactured so as to minimize deformation.

[0003]

However, as shown in FIG. 1, when a steel strip 1 having a thickness of 0.10 to 1.0 mm after shape correction is wound on a tension reel 2 and formed into a steel strip coil 3, the winding at the beginning of the winding is started. 4 (From the set hole diameter of the tension reel mandrel diameter, 5 to 50 mm thick part, 50 to 500 m length from the tension reel winding tip in steel strip length)
However, there is a problem that a shape defect in which both ends in the width direction of the steel strip 1 undulates in the longitudinal direction of the steel strip (generally called ear waves), quality is remarkably impaired, and the yield is greatly reduced.
The method of the present invention has been made in order to advantageously solve such a problem, and it is an object of the present invention to provide a method of winding a steel strip after shape correction, which hardly generates an ear wave shape defect. is there.

[0004]

The feature of the present invention is that when the steel strip after shape correction is wound on a tension reel mandrel, the diameter of the tension reel mandrel is 1 mm during the winding immediately after the initial winding of the steel strip. This is a method for winding a steel strip, characterized in that it is enlarged below .

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Generally, a plate thickness of 0.1 to 1.0 mm
In steel strip processing lines such as plating equipment for processing thin steel strip, coil preparation equipment, tension leveler equipment for shape correction, and temper rolling equipment, the diameters of rolls and tension reels for threading pass the line. For passing steel strip,
In order to prevent plastic deformation due to bending deformation of these rolls, the rolls have a diameter larger than the yield curvature.
If the curvature coefficient β is defined as β = hE / DY (1) using the plate thickness h, the elastic modulus E, the diameter D of rolls, and the yield stress of the steel strip as Y, β <1 Especially in the case of thin steel strip such as steel strip for cans, β
Generally, a large-diameter roll diameter is set so as to be <0.5.

However, according to the results of analysis by the present inventors, the cause of the above-mentioned defective shape of the steel strip is as follows.
When winding onto a tension reel that should not be plastically deformed, not only the bending stress caused by winding the steel strip around the tension reel, but also the circumferential compressive stress of the steel strip caused by tightening of the winding due to winding and the inside of the steel strip It was found that the steel strip was plastically deformed due to the application of residual stress. Also, the tightening force of the steel strip coil,
It was also found that the deformation of the steel strip on the tension reel could not be analyzed because the residual stress of the steel strip was not taken into account. When the steel strip after shape correction is wound on a tension reel, a tensile stress equal to the winding tension is applied to the steel strip in the initial stage of winding the steel strip, but as the number of windings increases, the outer circumference of the coil increases. Due to the circumferential compressive stress of the steel strip caused by tightening of the winding from the part, the steel strip is strongly compressed at the beginning of winding, and the tension reel mandrel around which the steel strip is wound contracts due to elastic deformation and decreases in diameter. Compressive strain is applied to the steel strip in the initial stage of removal. That is, the steel strip in the early stage of winding is in a deformed state of compression bending in the longitudinal direction of the steel strip. If the 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, the steel strip is formed with a sheet crown in the width direction of the steel strip (the center in the width direction of the steel strip is slightly thicker, and both ends are slightly thinner). Since the force for compressing the initial stage of winding in the center portion in the band width direction is large, the compressive strain also increases in the center portion in the width direction, and the length of the steel band in the center portion in the width direction is shortened. Also, even if a steel strip of uniform thickness in the width direction without a sheet crown is wound around a tension reel and a uniform compressive force is applied to the mandrel, from the theory of material mechanics, the central part in the sheet width direction is better than the end part. This leads to a larger deformation of the mandrel. That is, in the coil wound around the tension reel, when the inner diameter of the coil is deformed by the tightening force, the central portion of the width of the steel strip tends to be shorter. That is, the length of the central portion in the width direction of the steel strip is short, and when the coil is rewound to remove the constraint of the steel strip, the end of the steel strip becomes relatively long. That is, this appears as a shape defect of the ear wave.

Further, the inventors of the present invention have studied mechanically the deformation state of the steel strip when the steel strip is wound on a tension reel, and found that the diameter of the tension reel is Dr (mm) and the amount of reduction in the diameter of the reel mandrel caused by winding. Let ΔD1 be the strain amount εc1 of the compression of the steel strip near the inner diameter of the coil caused by the reel mandrel deformation.
Therefore, εc1 = ΔD1 / Dr (2) (Here, the signs of the compressive stress and the compressive strain are defined as positive.) Then, in order to remove the wound steel strip coil from the tension reel, when the mandrel is reduced, the tightening force from the coil outer peripheral portion until now is obtained. Since the resistance of the mandrel supporting the coil disappears, the steel strip near the inner diameter of the coil is compressed and further contracted by ΔD2 in diameter. Since the diameter near the inner diameter can be regarded as almost Dr, the compressive strain Δε at that time
2 becomes εc2 = ΔD2 / Dr (3) The sum of the compressive strains εc1 + εc2 was large at the center in the width direction, and at the edge of the plate, the measurement result was a fraction of the width center. The bending strain εb of the steel strip in the initial stage of winding the steel strip wound on the tension reel is obtained as εb = h / Dr (4) based on the thickness h and the reel diameter Dr, and the reel-side surface layer of the steel strip is compressed. Strain, tensile strain is applied to the opposite surface layer. This strain is almost constant in the width direction of the steel strip; however, the distribution of the residual stress in the longitudinal direction of the thin steel strip subjected to shape correction is measured in detail, and the results show that the compression of Has a residual stress of
There is a tensile residual stress in the center of the steel strip thickness. Assuming that the residual stress of the compression of the surface portion of the steel strip is σs (here, the sign of the compression stress is defined as positive), the residual strain εs of the surface of the steel strip due to the residual stress σs is obtained by using the elastic coefficient E as εs = σs / E (5). Therefore, the total strain introduced into the reel-side surface layer of the wound steel strip is: εc1
+ Εc2 + εb + εs. Yield strain εe of steel strip
Is obtained from the yield stress Y and the elastic modulus E of the steel strip. Εe = Y / E (6) Since the sum of the various types of compressive strain applied to the steel strip in the initial stage of winding the steel strip is larger than εe, The band is plastically deformed, and the permanent set εp (the steel band becomes shorter in the longitudinal direction) remains as in the following equation. [epsilon] p = ([epsilon] c1 + [epsilon] c2 + [epsilon] b + [epsilon] s)-[epsilon] e (7) The shape defect of the inner diameter of the coil at the time of winding the steel strip, which is to be solved by the method of the present invention, is expressed by:
> 0, and since the central part in the width direction of the steel strip is large and the end part in the width direction of the steel strip is small, it appears in the shape of an ear wave.

[0009] The reason that the shape defect occurs only in the initial winding of the steel strip is that the steel strip itself wound in the initial winding acts as a sleeve which is often used to prevent the collapse of the coil and has an outer diameter portion. In order to oppose the circumferential compressive stress of the steel strip due to tight tightening of the steel strip, on the outer peripheral side of the steel strip coil, the compressive strain of the above equation (3) is reduced, and the bending strain of the equation (4) is also reduced. Because the thickness is the ratio between the bending diameter and the diameter of the steel strip coil, the winding becomes thicker on the outer diameter side, and the diameter becomes smaller as the diameter becomes larger. . Also, in practice, even if there is permanent set, if the set is small, it does not appear as a shape defect in the steel strip, and it is rare that the outer shape of the steel strip wound around the coil becomes defective.

Therefore, from the equation (7) representing the plastic strain generated by winding, in order to prevent the occurrence of a shape defect, it is necessary to set εp ≦ 0 so that the entire steel strip is kept in the elastic deformation region over the entire width and the entire length. , Εp> 0, it does not result in a shape defect in which ear waves are generated. The condition of εp ≦ 0 is a steel strip having a large yield stress,
In other words, if a steel strip that is hard and hard to deform is selected, εe becomes large as shown in equation (6), and it can be easily achieved, but the yield stress is determined for the steel strip application and the manufacturer can change it without permission Can not do it. Further, in order to reduce the compressive strain εc1 in the expression (2), a method of winding on a tension reel having strong rigidity that can withstand the winding tightening force due to the winding tension may be considered. If the diameter of the reel is reduced when the coil is removed from the tension reel, the stiffness of the steel strip alone cannot withstand the tightening force. It will be bigger than when. That is, εc1 + εc2 does not change much, and the effectiveness is considerably reduced.

Thus, in the method of the present invention, the tightening force applied at the initial stage of winding the steel strip on the tension reel is greatly reduced, thereby reducing εp in the above-mentioned equation (7), and preventing a shape defect. The method is as follows. When winding the steel strip on the tension reel, by expanding the tension reel mandrel during the winding of the steel strip immediately after the initial winding of the steel strip,
The outer diameter portion of the coil is further wound around the outer periphery of the coil in the initial stage of winding the expanded steel strip.
When the tension reel mandrel is expanded or not expanded, if the expansion amount is 1 mm or less, the coil will be elastically deformed at the initial winding of the steel strip,
This is the initial coil of the same diameter steel strip winding. However,
When the mandrel is enlarged, the outer diameter portion has a diameter that is substantially larger than the case where the mandrel is not enlarged. When the coil of the steel strip coil is completed and the coil is removed from the tension reel and there is no longer any support for the inner diameter of the coil, the tightening force applied to the initial part of the coil of the steel strip coil will be increased. Pressure due to interference fit between the outer diameter portion and the coil outer diameter portion. Here, when the coil detached from the tension reel is a tightly fitted state of the cylinder formed of the steel strip winding initial portion and the cylinder formed of the outer diameter portion, the following analysis can be performed. When wound without increasing the diameter of the tension reel mandrel, the outer diameter when the inner and outer pressures are not applied to the cylinder that is the initial part of coil winding is Dio, and the inner diameter when the inner and outer pressures of the cylinder that is the outer diameter part are not applied Is Doi, and if P is the surface pressure applied to the initial winding portion of the coil due to the tightening force, P∝Dio-Doi (8). On the other hand, when the tension reel mandrel is enlarged by ΔDh in the initial stage of winding the steel strip, the winding surface pressure Pa becomes substantially Pa∝ (Dio−Doi) −ΔDh (9). Therefore, the expressions (8) and (9) are obtained. From Pa ≒ P × ≒ 1−ΔDh / (Dio−Doi)｝ (10), Pa becomes significantly smaller than P.

According to the results of various studies by the present inventors,
A steel strip having a thickness of 0.1 to 1.0 mm and a width of 600 to 1600 mm is applied to a steel strip having a tension of 2.5 to 4.5 kgf / mm ² and a diameter of 400.
Weight 10 to tension reel mandrel of ~ 600mm
When the winding coil is used for up to 28 t, the winding initial portion of the steel strip causing the shape defect is 50 mm from the winding tip.
５００500 m, and Dio-Doi is approximately 0.1 to 1.
0 mm. In this case, by expanding 0.05 to 1.0 mm immediately after the initial winding of the steel strip, the winding surface pressure Pa can be significantly reduced, and the initial part of the steel strip winding due to tightening can be reduced. Circumferential compressive stress of 1
0 to 20 kgf / mm ² can be reduced. However, if the tension reel mandrel is enlarged too much, the initial winding of the steel strip will cause plastic deformation due to the expansion of the mandrel, and the surface pressure between the initial winding of the steel strip and the outer diameter will decrease. It is not preferable because slipping occurs and scratches are generated.
m or less. The lower limit varies depending on the steel strip size, winding tension, etc., but under the above conditions,
With a thickness of 0.05 mm, shape defects can be reliably prevented. In the case of a steel strip with a low roughness, a lubricated steel strip, or the like, which is easy to slip, expand the tension reel mandrel in multiple times or expand it continuously while winding a certain amount. By doing so, the surface pressure between the layers of the winding coil is not greatly reduced locally, but the portion where the surface pressure is reduced is dispersed at a plurality of locations, and the same effect as when a predetermined amount is expanded at a time by averaging. Can be obtained.

As described above, according to the method of the present invention, when the steel strip after the shape correction is wound on the tension reel, the diameter of the tension reel mandrel is adjusted immediately after winding the steel strip at the beginning of winding.
By expanding by 1 mm or less and reducing the tightening force applied at the beginning of the winding of the steel strip, the circumferential compressive stress applied at the beginning of the winding of the steel strip is reduced, and the defective shape of the steel strip is reliably prevented.

Immediately after the initial winding of the steel strip in which the tension reel mandrel is expanded, as described above, the initial winding of the steel strip is 5 to 50 mm in the winding thickness and 50 to 50 mm from the winding tip in the steel strip length. Immediately after this, the winding thickness is more than 50 mm
Between 0 mm and more than 500 m to 1000 m in steel strip length. Therefore, the tension reel mandrel is expanded as described above during the winding of the steel strip.

Next, the method of the present invention will be described with reference to the drawings. In FIG. 1, when the steel strip 1 after shape correction is wound on a tension reel (mandrel) 2, an initial winding of the steel strip 4 (from a set hole diameter of the tension reel mandrel diameter, a 5 to 50 mm thick portion, a steel strip length) Immediately after the length of the tension reel from 50 to 500 m from the winding end of the tension reel 5 (more than 50 mm and 100 mm in winding thickness, more than 500 m in steel strip length 1)
The tension reel (mandrel) 2 is enlarged during the winding of the steel strip of 000 m) to remove a compressive stress that may cause a defective shape (ear wave) of the steel strip.

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

[Table 1] Note 1: Steel strip composition (% by weight), C: 0.04 to 0.12, Mn: 0.30 to
0.45, Si: 0.005, P: 0.015-0.025, S: 0.01-0.02, So
l.Al:0.01, Ti: trace, Nb: trace, steel strip thickness 0.18 ~ 0.90mm, steel strip width 715 ~ 1200mm consisting of remaining Fe and impurities, temper degree T4 ~ T5 Annealing, followed by temper rolling at a reduction of 1.5 to 2.0%. Then
Winding on a tension reel is from 2000 to 3500
With winding, about 1 at an average winding speed of 400 to 600 m / min.
A 5t coil was used. Note 2: In the steel strip shape correction, the one denoted by SP indicates a steel strip wound up after temper rolling, and the steel strip subjected to shape correction by a tension leveler after temper rolling is denoted by TL. Note 3: The tension reel is enlarged at the initial stage of winding of the steel strip (5 to 50 mm winding thickness, 5 mm from the winding end in steel strip length).
Immediately after (0 to 500 m) (between 50 mm and 100 mm, between 500 m and 1000 m from the winding tip with the steel strip length)
The mandrel of the tension reel was activated during the winding of the steel strip to increase the reel diameter. Note 4: The evaluation of the steel strip ear wave is as follows: When the steel strip is cut out every 2 m at the beginning of winding the steel strip (200 m from the winding tip) and placed on a horizontal surface plate, the wave height at the end of the steel strip is 1.5 mm. Less than ear wave generation less than, medium wave height of 1.5-3.0mm,
The wave height of 3.0 to 4.5 mm was large, and the wave height of over 4.5 mm was oversized. If it can be small, it will pass in most applications. In the case of an ear wave, it is rejected in severe applications, and in the case of an ear wave size, it is rejected in all applications.

[0017]

According to the method of the present invention, it is possible to reliably prevent a shape defect (ear wave, etc.) at the initial winding, which occurs when the steel strip is wound after the shape correction in the temper rolling. The quality can be improved, the yield can be increased, and an extra step for cutting off the defective shape portion is not required. Also, it does not require significant equipment remodeling, and
It requires little running cost and can be inexpensive. Further, excellent effects such as improvement of quality while maintaining the conventional high productivity can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view showing winding of a steel strip on a tension reel.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-142759 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21C 47/02 B21C 47/30

Claims (1)

(57) [Claims] 1. A winding method for a steel strip, wherein the diameter of a tension reel mandrel is increased by 1 mm or less during the winding immediately after the initial winding of the steel strip when the steel strip after shape correction is wound on a tension reel. Characteristic looper tension control method when steel strip breaks.