JPH0957342A - Winding method for steel strip - Google Patents

Abstract

(57) Abstract: The present invention method is a winding method for surely preventing seismic waves at both ends of a steel strip that occurs at the initial stage of winding when winding a steel strip after shape correction such as temper rolling. I will provide a. SOLUTION: When winding a shape-corrected steel strip on a tension reel, bending is performed in the steel strip winding direction on the tension reel, and the surface layer portion of the steel strip on the tension reel side is plastically deformed so that the steel strip remains compressed. It is a method of winding a steel strip that reduces stress and then winds it.

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. 3, for example, when the steel strip 1 for cans having a plate thickness of 0.15 to 0.40 mm after shape correction is wound on the tension reel 2 to form the 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]

The feature of the present invention resides in that, when the shape-corrected steel strip is wound onto a tension reel, the steel strip is bent in the winding direction of the steel strip onto the tension reel. This is a method for winding a steel strip characterized by plastically deforming the surface layer on the reel side to reduce the compressive residual stress of the steel strip, and then winding.

[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 is based on the plate thickness and steel strip material.
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 the shape-corrected steel strip is wound on a tension reel, the steel strip in the initial stage of winding 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 steel strip in the initial stage of winding to be strongly compressed, and the tension reel mandrel around which the steel strip winds contracts due to elastic deformation, resulting in a smaller diameter. As a result, compressive strain is applied to the steel strip in the initial 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 compressing force at the center of the width direction is large at the initial stage of winding, the compressive strain also becomes larger at the center of the width direction, and the length of the steel strip at the center of 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 winding stage among the steel strips wound on the tension reel is determined as εb = h / Dr (4) from the strip thickness h and the reel diameter Dr, and the surface layer on the reel side of the steel strip is obtained. Part is subjected to compressive strain, and 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.

A defective shape occurs only in the initial steel strip of the steel strip wound on the tension reel because the steel strip wound in the initial stage of winding serves as a sleeve often used for preventing coil collapse. In order to counter the winding tightening force from the outer diameter part, on the outer peripheral side of the steel strip coil, the above (2) (3)
The total of the compressive strain in the formula is small, and the bending strain in the formula (4) is also the ratio of the plate thickness and the bending diameter of the steel strip. Therefore, it becomes smaller as the diameter becomes larger by winding on the outer diameter side of the steel strip coil. This is because the condition of εp ≦ 0 in Expression (7), that is, the elastic deformation region is easily entered. In reality, even if there is a permanent strain, if it is small, it does not appear in the steel strip as a defective shape, so it is rare for the outer circumference of the steel strip wound around the coil to become defective.
Since the bending strain of the equation (4) increases in proportion to the steel strip thickness h, it is considered that the thicker the steel, the easier it is to enter the plastic deformation region, and the thicker the steel, the poorer the shape. 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 equation, εe becomes large and can be easily achieved, but the yield stress is determined by the steel strip specifications of the consumer and cannot be arbitrarily changed by the manufacturer. Also, (2)
In order to reduce the compressive strain εc1 of the formula, a method of winding on a tension reel that has a strong rigidity to withstand the winding tightening force due to the winding tension can be considered, but in reality, the wound steel strip coil is pulled from the tension reel. If the reel diameter is reduced during withdrawal, the rigidity of the steel strip alone cannot withstand the winding tightening force, and eventually the compression strain εc2 due to reel withdrawal shown in equation (3) becomes larger than that with a less rigid reel. . That is, εc1 + εc
A value of 2 does not change much and the effectiveness decreases considerably. In addition, the inner diameter sleeve used to prevent coil crushing that tends to occur in thin steel strips (in the normal manufacturing process,
Steel cylinder with plate thickness 2-5 mm, or thickness 10-20
mm paper cylinder etc.) is used as a strong sleeve having high rigidity, for example, a steel sleeve having a thickness of about 30 mm, and if the coil is rewound without pulling out this sleeve, both εc1 and εc2 are almost 0. However, such a sleeve is too heavy and there is a problem that the coil and the sleeve can hardly be handled unless special equipment is provided.

However, in the method of the present invention, in order to satisfy the condition of εp ≦ 0 in the above equation (7),
A method for reducing the compressive residual stress σs of the surface layer of the steel strip of the formula (4) was found. In the steel strip after shape correction, somewhere before winding up, the tension reel is wound up in the initial stage (steel strip part where shape failure occurs under conventional winding conditions of conventional technology, strip thickness, width, winding Although it varies depending on the tension, etc., a steel strip having a length corresponding to about 20 to 50 mm thick winding portion and a length of steel strip from the winding tip to about 200 m)
It is bent in a winding direction to a tension reel to reduce the compressive residual stress of the surface layer generated by the shape correction and prevent the shape defect of the selvage wave accompanying the winding of the steel strip.
That is, by bending the steel strip in the winding direction on the tension reel in this manner, the surface layer portion having a high compressive residual stress generated by the shape correction is preferentially plastically deformed, so that the compressive residual stress of the reel side surface layer is reduced. Reduce.

In order to reduce or remove the compressive residual stress in the surface layer of the steel strip having the shape-corrected steel strip as described above, it is used in a usual 0.15 to 0.4 mm thick steel strip processing line. A bending roll having a smaller diameter than the existing roll having a diameter of 200 to 400 mm is required. The optimum roll diameter changes depending on the thickness of the steel strip and the yield stress, but the diameter is generally 100.
Bending rolls of ~ 200 mm or less are used to impart positive plastic bending to the steel strip. This bending needs to give plastic bending deformation to the tension reel side. The criteria for determining whether or not the steel strip can be yield-bent is
As a plastic bending condition of a steel strip having a residual stress, it can be calculated that the yield stress is apparently reduced by the residual stress in the formula (1). Therefore, Y-σs is defined as hE / D (Y-σs)> 1 (8 ) Is the surrender condition. Rewriting Eq. (8) with the curvature coefficient β defined in Eq. (1), β (= hE / DY)> 1.0− (σs / Y) (9) is necessary to obtain the effect of the present invention. It becomes a conditional expression. The compressive residual stress of the surface layer of the steel strip due to shape correction is 50% of the yield stress.
It is a finding of the inventors of the present invention that it often becomes about%, and when σs = 0.5Y, the condition of β> 0.5 is a condition that the steel strip surface layer is plastically deformed by the bending roll. In the method of the present invention, when plastic bending is applied, it becomes difficult for plastic deformation to occur in the bending in the same direction (residual stress is reduced).
Since the bending roll under the condition of the equation (9) can give plastic deformation to the entire width of the steel strip, when it is finally wound up on the tension reel, the plastic deformation amount changes in the width direction of the steel strip. This prevents the ear wave from being defective in shape. This bending is theoretically effective if only plastic deformation is given, but if the bending is too strong, the warping due to the bending becomes large, the damage of the warping begins to appear, and new residual stress occurs in the steel strip. Not preferable. When expressed by the curvature coefficient β in the equation (1), a desirable range is up to β <2. As described above, the range of the bending roll for preventing the defective shape is β = hE / DY, and therefore 0.5 <(hE / DY) <2 (10) is a desirable range. Generally E = 20 for steel strips
It is 6 GPa. Here, the roll diameter D may be the roll diameter itself when the wrapping angle of the steel strip is large, for example, 45 degrees or more, but when the wrapping angle is small, the steel strip can bend only to a diameter larger than the roll diameter.
In that case, the actual curvature κ of the steel strip is calculated and calculated with D = 2 / κ.

As described above, the bending by the bending roll for reducing the compressive residual stress of the steel strip is carried out at the initial stage of winding the steel strip of the tension reel (a winding thickness of 20 to 50 m) in which a defective shape appears.
m, the length of the steel strip is 50 to 200 m from the winding tip), but if it is difficult to adjust the position of the bending roll during winding the steel strip, bend it over the entire length until the winding of the steel strip is completed. There is no problem with applying. That is, at least in the initial stage of winding the steel strip, the residual compression stress is reduced and the strip is wound on the tension reel. If the bending roll is equipped with a mechanism that allows the position to be adjusted freely, the wrap angle of the bending roll is reduced when the steel strip is thick, and the wrap angle is increased when the steel strip is thin. It is also possible to change the curvature κ and follow the change of the optimum condition due to the plate thickness of the curvature coefficient β.

Since the steel strip is bent in the winding direction of the tension reel to be plastically deformed as described above, the steel strip is warped in the winding direction of the tension reel, and the steel strip is rewound in the next process, When the sheet is sheared, it may interfere with the threading in the next process equipment.In order to prevent such warpage, prevent warpage that is bent in the direction opposite to the tension reel winding direction. By applying it, it is possible to prevent the warp. A plate warp prevention roll that applies bending to prevent this plate warp is provided between the bending roll and the tension reel, that is, when provided on the downstream side of the bending roll, a larger diameter than the bending roll is desirable,
It is desirable that the roll diameter is more than 1.0 to 1.5 times the bending roll diameter. When it is provided on the upstream side of the bending roll, the diameter is preferably smaller than that of the bending roll, and it is desirable that the diameter of the bending roll is 0.7 to less than 1.0 times. Such a warp prevention roll and a bending roll are effective even if installed anywhere from the shape correction to the tension reel after the shape is corrected and if the above conditions are satisfied. Such a warp prevention roll can adjust the winding angle. That is, if a position adjusting function is provided so that the pushing amount of the warp prevention roll into the steel strip pass line can be controlled, the warp prevention can be more easily achieved. When the steel strip is processed in a process that does not hinder the passing of the steel strip even if the steel strip warps, only the bending roll is required, and the strip warp prevention roll is not required.

Next, the method of the present invention will be described with reference to the drawings. In FIG. 1, when winding the steel strip 1 which has been shape-corrected by temper rolling or the like onto the tension reel 2 as a coil 3 via the rolls 5, 6 and 7 for stripping, a bending roll 8 is used.
Thus, at least the steel strip 1 in the initial stage 4 of winding is bent in the winding direction of the tension reel 2 to prevent a defective shape.

In FIG. 2, at the time of winding the steel strip 1 which has been shape-corrected by temper rolling or the like onto the tension reel 2 as the coil 3 via the rolls 5 and 7 for stripping, at least the winding is performed by the bending roll 8. The steel strip 1 of the initial stage 4 is bent in the winding direction of the tension reel 2, the surface layer portion of the steel strip 1 on the side of the tension reel 2 is plastically deformed to reduce the compressive residual stress, and then in the winding direction of the tension reel 2 downstream from the bending position. On the side, the steel strip 1 is bent in the winding direction of the tension reel 2 by the warp prevention roll 9 to prevent the warp of the steel strip 1 and is bent in the opposite direction, and then is corrected to the tension reel 2. Roll up. Tension reel 2
After bending the steel strip 1 in the winding direction of the tension reel 2 with a warp prevention roll (not shown) on the upstream side of the bending position in the winding direction and bending warp correction in the opposite direction,
By winding the steel strip around the tension reel 2, it is possible to prevent the shape defect of the steel strip and prevent the warp of the strip.

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

[Table 1]

[Table 2]

[Table 3] Note 1: Steel strip component weight%, 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, S
ol.Al: 0.01, Ti: trace, Nb: trace, residual Fe and impurities with a steel strip thickness of 0 to 0.32 mm and a steel strip width of 900 mm. It was annealed so as to be ~ T5, and then temper-rolled with a rolling reduction of 1.5 to 2.0%. Then, winding on the tension reel,
A coil of 2000 to 3500 was used to make a coil of about 15 t. Note 2: The steel strip shape correction indicated as SP indicates a steel strip rolled after temper rolling. After temper rolling, the steel strip whose shape was corrected by the tension leveler was denoted as TL. Note 3: The bending of the steel strip on the tension reel was performed from the initial winding of the steel strip to the completion of winding. Note 4: For bending to prevent plate warping, the steel strip was bent in the direction opposite to the winding direction on the tension reel. Examples 4, 5
Bending to prevent plate warping other than the above was performed on the downstream side of the position of winding the steel strip around the tension reel. In Example 4, bending for preventing plate warpage was not performed, and in Example 5, it was performed on the upstream side of the position in the winding direction of the steel strip on the tension reel. Note 5: For the warp of the steel strip, cut out the steel strip at the initial stage (150 m from the winding end) of winding the steel strip on the tension reel every 1 m length and hang it in the air with the center of the width direction end of the steel strip. Deflection amount of steel strip is expressed in mm. Deflection of 10 mm or less does not cause plate warp, 10 to 30 mm indicates small plate warp, 30
A plate warp of ~ 60 mm was described, and a plate warp larger than that was described as a large plate warp.
A warp larger than that of the plate warp often causes a problem when the steel strip is used. Note 6: Steel strip ear waves are evaluated by cutting out the steel strip every 1 m.
When placed on a horizontal surface plate, the wave height of the steel strip edge is 1.5 m
The generation of ear waves of less than m is small, the wave height of 1.5 to 3.0 mm is medium, 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.

[0018]

EFFECTS OF THE INVENTION According to the method of the present invention, it is possible to reliably prevent the seismic waves at both ends of the steel strip at the initial stage of winding, which occur during winding of the steel strip after shape correction such as 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. Also, since it is only necessary to add bending rolls or to add or modify equipment to the extent that the diameter of existing strip passing rolls is changed,
It is possible to prevent seismic waves at both ends of the steel strip at low cost.
Further, once the roll condition is designed, the method of the present invention does not require any extra control, so that it is possible to obtain excellent effects such as improving the quality while maintaining the conventional high productivity.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example of a method of the present invention.

FIG. 2 is a flow chart showing an example of the method of the present invention.

FIG. 3 is a side view showing a state of winding a steel strip around a tension reel.

Claims (2)

[Claims] 1. When the steel strip after shape correction is wound on a tension reel, the steel strip is compressed by bending the steel strip on the tension reel in the winding direction of the steel strip and plastically deforming the surface layer of the steel strip on the tension reel side. A method for winding a steel strip, which comprises reducing residual stress and then winding. 2. The winding of a steel strip according to claim 1, wherein bending is performed in the opposite direction on the upstream side or the downstream side where bending is performed in the winding direction of the steel strip on the tension reel to prevent plate warpage. Method.