JPH0957344A - Method for coiling steel strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent edge waving on the both end parts of a steel strip in the initial stage of coiling by forming a crown on the central part in the width direction of a tension reel and coiling the steel strip. SOLUTION: A steel strip is coiled on a tension reel 2 with a crown formed by 0.2 to 20mm at the position of 30 to 90% in the central part of width direction of the tension reel (mandrel) 2 and it is made to a steel strip coil 3. In this case, the winding amount of steel strip at the position of the crown part 5 of the reel 2 is made large, the crown 5 is compressed and made small with the tightening force of winding, the reel 2 is shrunk and in the final coil state after being pulled out, the diameter distribution of the steel strip in the width direction of initial stage 4 of coiling is made uniform. Therefore, the quality of the steel strip is improved and the yield can be also improved.

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, for example, when a steel strip 1 for a can having a plate thickness of 0.15 to 0.40 mm after shape correction is wound on a tension reel 2 to form a steel strip coil 3. , Initial winding 4 (from the set hole diameter of the tension reel mandrel diameter, 20 to 50 mm thick winding portion, and the length of the steel strip from the tension reel winding end to 50
The widthwise ends of the steel strip 1 (about 200 m in length) wavy in the longitudinal direction of the steel strip (generally referred to as selvage waves), resulting in a defective shape.
There is a problem that the quality is significantly 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 the shape-corrected steel strip is wound on a tension reel, the steel strip is wound by forming a crown at the widthwise center of the tension reel. It is a steel strip winding method characterized by taking.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Generally used in beverage cans and the like 0.1
For example, in a steel strip processing line such as a plating equipment for processing a steel strip for cans, a coil preparation equipment, and a tension leveler equipment for performing shape correction, the diameters of the sheet passing roll and the tension reel are 5 to 0.4 mm. The steel strip passing through the line has a diameter larger than the yield curvature so as not to be plastically deformed by the bending deformation of these rolls. If the curvature coefficient β is expressed as an equation, β = hE / DY (1) using the plate thickness h, elastic coefficient E, roll diameter D, and yield stress of steel strip as Y, β ≤ 1 In particular, in the case of thin steel strips such as steel strips for cans, β
It is common to set a large roll diameter such that ≦ 0.5.

However, according to the result of analysis by the present inventors, the cause of the shape defect of the steel strip is as follows.
It was found that this is caused by the plastic deformation of the steel strip due to the winding tightening force and the residual stress inside the steel strip that are applied during winding on the tension reel, which should not be plastically deformed. It was also found that the deformation of the steel strip on the tension reel could not be analyzed because the tightening force of the steel strip coil and the residual stress of the steel strip were not taken into consideration. When winding the shape-corrected steel strip on a tension reel, the steel strip in the initial stage of winding the steel strip has a tensile stress equal to the winding tension.
As the number of turns increases, the tightening force from the outer circumference of the coil causes the coil to be strongly compressed in the initial stage of winding, and the tension reel mandrel around which the steel strip is wound contracts due to elastic deformation and the diameter decreases. Along with this, 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.) Then, to remove this wound steel strip coil from the tension reel, when the mandrel is contracted, the winding tightening force from the coil outer periphery until now. 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 Dr, the compressive strain Δε at that time
2 becomes 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. On the other hand, this strain is almost constant in the width direction of the steel strip.On the other hand, the distribution of the residual stress in the longitudinal direction of the thin steel strip that has undergone shape correction at the thickness position is measured in detail. Has residual stress of
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.

Deformation occurs only in the rolled steel strip in the initial winding stage because the rolled steel strip in the initial winding stage serves as a sleeve often used to prevent the coil from collapsing, and the outer diameter portion. In order to counter the winding tightening force from the above, the total of the compressive strains of the above formulas (2) and (3) becomes small on the outer peripheral side of the steel strip coil, and the bending strain of the formula (4) also depends on the plate thickness of the steel strip. Since it is the ratio of the bending diameter, it becomes smaller as the diameter increases with winding on the outer diameter side of the steel strip coil.
This is because the condition of εp <0 in the equation, 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. The bending strain of equation (4) is
Since the thickness increases in proportion to the steel strip thickness h, it seems that the thicker the steel, the easier it is to enter the plastic deformation region, and the thicker the steel, the more likely it is that the shape will be poor. However, in a steel strip having a steel strip thickness of about 0.8 mm, for example, a steel strip for automobiles and the like, the shape defect of the inner circumference of the coil does not pose a problem, and the steel strip for a can having a small thickness of 0.15 to 0.4 mm is used. The problem with shape failure is that even if a thick coil is wound with the same tension per unit area as the product becomes thicker, the winding tightening compressive force becomes smaller because the number of windings is small, and This is because, even if the strain difference in the band is equal, the buckling stress is larger as the material is thicker, and thus the shape defect due to the generation of the ear wave is less likely to be manifested.

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. , Even if the plastic bending deformation condition is εp> 0, there is no difference in the width direction of the change in the length of the steel strip even if there is a curl due to the plastic bending and a warp occurs if the strain is uniform in the width direction. Therefore, the shape of the ear wave is not defective. The condition of εp ≦ 0 is (6) if a steel strip with a large yield stress, that is, a steel strip that is hard and difficult to deform is selected.
As shown in the formula, εe becomes large and can be easily achieved, but the yield stress is determined by the steel strip application and cannot be arbitrarily 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. Furthermore, an inner diameter sleeve used to prevent coil crushing that tends to occur in thin steel strips (a plate thickness of 2
A 5 mm steel cylinder, or a 10-20 mm thick paper cylinder, etc.) is used as a rigid sleeve with high rigidity.
For example, if you use a steel sleeve with a thickness of about 30 mm and rewind the coil without removing this sleeve,
Since both εc1 and εc2 can be set to almost 0, ear waves can be prevented, but such a sleeve is too heavy, and there is a drawback that the coil and the sleeve can hardly be handled unless special equipment is provided.

In the method of the present invention, however, the inventors have found a method capable of preventing a defective shape by equalizing the strain amounts in the width direction even if εp> 0 in the above formula (7). As described above, the steel strip is wound by forming a crown in the widthwise central portion of the tension reel as described above, and if a conventional conventional tension reel mandrel with a constant diameter is used, the steel strip is The contraction amount of the mandrel diameter due to the elastic deformation of the mandrel due to the plate thickness crown and the winding tightening force that it has originally.
D1 has a parabolic distribution that increases in the widthwise central part, and the central part in the widthwise direction of the steel strip is compressed and shortened in length, but the reel part supports the steel strip at the end of the steel strip. Even when elastically deformed or plastically deformed, the compression strain is smaller than the central width.

According to the method of the present invention, a crown is formed in the central portion in the width direction of the tension reel (mandrel), and the steel strip is wound to form a crown in the central portion in the width direction of the steel strip. The action is to pre-expand the central portion of the reel mandrel so as to compensate for the total amount of the contraction of the reel mandrel diameter due to the winding tightening force and the contraction amount after the steel strip coil is extracted from the reel. The optimum crown when mainly utilizing such an action forms the crown on the reel at 30 to 90% of the portion in the width direction of the steel strip, and the crown amount is 0.
It may be inflated in the range of 2 to 20 mm. The range in which the crown is applied and the amount of the crown can be determined from the amount of compressive strain measured by attaching a strain gauge to the inner diameter of the coil. When the width of the crown formed on the mandrel is smaller than 30% in this manner, the winding tightening force is excessively concentrated in the central portion and the shape in the width direction of the steel strip coil may be disturbed. When the maximum is more than 90% of the width of the steel strip, the supporting force of the mandrel (reel) becomes excessive at the end of the strip, reducing the amount of shrinkage of the strip and increasing the difference from the shrinkage of the steel in the widthwise central part. This is not desirable. The crown formed on the tension reel is 3 in the width direction of the steel strip.
Since it suffices to have a maximum crown of 0.2 to 20 mm at 0 to 90%, a parabolic shape, a trapezoidal shape or the like can be adopted as the cross-sectional shape of the crown. When it is convex and has a corner, it is desirable to add R in order to prevent shape deformation at the corner.

Next, the method of the present invention will be described with reference to the drawings. In FIG. 1, the crown 5 is moved to the tension reel (mandrel) 2 at a position of 30 to 90% of the central portion in the width direction.
A steel strip coil 3 is formed by winding a steel strip around a tension reel 2 having a thickness of 2 to 20 mm. At this time, the winding amount of the steel strip in the crown 5 portion of the reel (mandrel) 2 becomes large, and the crown 5 is compressed and becomes small by the winding tightening force, and the final coil after the reel (mandrel) 2 is contracted and extracted. In the state, the steel strip diameter distribution in the width direction in the initial stage 4 of winding is uniform, and the generation of the ear wave at the end portion of the steel strip coil 3 in the width direction in the initial stage 4 of winding is prevented.

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

[Table 1] 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
, Ol.Al:0.01, Ti: traces, Nb: traces, residual Fe and impurities with a steel strip thickness of 0.18 to 0.32 mm and a steel strip width of 900 mm. ~ T5
And then temper-rolled at a rolling reduction of 1.5 to 2.0%. Next, the winding on the tension reel was 2000 to 3500 windings, and a coil of about 15 t was used. Note 2: For the steel strip shape correction, the one denoted by SP indicates a steel strip rolled after temper rolling, and the steel strip subjected to shape correction by the tension leveler after temper rolling is denoted as TL. Note 3: The crown is a convex crown,
The center of the width of the steel strip is the maximum crown, and the outside of the crown width is constant (the original diameter of the reel mandrel). As for the cross-sectional shape of the crown, the width edge and the outer edge of the center portion in the width direction were almost parabolic. Note 4: The crown was formed on the tension reel mandrel by overlay welding. Note 5: For the evaluation of steel strip seismic waves, when a steel strip at the initial stage of winding the steel strip (200 m from the winding tip) is cut out every 2 m and placed on a horizontal surface plate, the wave height of the steel strip edge is 1.5 mm. 2. Ear wave generation of less than is small, wave height of 1.5 to 3.0 mm is medium, 3.
The wave height of 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.

[0015]

EFFECTS OF THE INVENTION According to the method of the present invention, it is possible to reliably prevent seismic waves at both ends of the steel strip at the initial stage of winding, which occurs during winding of the steel strip after 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. The equipment can be modified by overlay welding on a tension reel mandrel or by covering the reel mandrel with a fixed sleeve (designed to be detachable) narrower than the steel strip width. It is possible to prevent the ear wave of the part. 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 winding of a steel strip according to a conventional method.

Claims (2)

[Claims] 1. A method of winding a steel strip, comprising winding a shape-corrected steel strip on a tension reel by forming a crown at the center of the tension reel in the width direction and winding the steel strip. 2. A tension reel having a width of 30 to 30 in the width direction of the steel strip.
90% to form a crown of 0.2 to 20 mm,
The steel strip winding method according to claim 1, wherein the steel strip is wound up.