JP2009034726A - Tension leveler - Google Patents

Abstract

In a conventional tension leveler, there is a problem that a material after correction has a large residual stress, and subsequent processing such as cutting and printing is difficult. This is because the tension leveler uses a roll to bend and correct the material.
Pressure is applied to both front and back surfaces of a metal strip between the entrance and exit bridle rolls of a tension leveler by means of hollow rolls, and correction is performed by tension. The material is not bent during the tension correction process, and the residual stress of the material after shape correction is small.
[Selection] Figure 1

Description

  The present invention relates to a tension leveler that corrects a shape defect of a metal strip (hereinafter referred to as a material).

A tension leveler used in the past is a cylindrical type in which a material is tensioned by an inlet-side bridle roll and an outlet-side bridle roll, and the material is divided into two upper and lower groups between the two bridle rolls and arranged in a staggered pattern. Using a roll, the material is repeatedly bent and corrected. (For example, refer to Patent Document 1 and Non-Patent Document 1).
These tension levelers usually have an extension roll portion and a shape correction roll portion, both of which are straightened by bending and pulling the material using a roll. For this reason, the material after correction is apparently flat due to the balance of residual stress, but there is a large residual stress inside the material. (For example, see Non-Patent Document 2)
Although the material is tensioned between the two bridle rolls and corrected without repeatedly bending, the tensile force is excessive and the material surface is easily damaged by sliding with the two bridle rolls.

Japanese Patent No. 3440083. Edited by Japan Society for Technology of Plasticity, Orthodontic Processing, Corona, published January 20, 1992, p. 90-129.

Non-patent document 2

Proceedings of the Japan Iron and Steel Institute, Materials and Processes, published March 1, 2003, Vol. 16 (2003) No. 2P. 384-387.

  The material corrected with the conventional tension leveler described above has large residual stress inside, and deforms again as the residual stress is released by subsequent processing, that is, cutting, surface dissolution removal, heat treatment, etc. Inconvenience occurred when printing on the surface of the paper.

  The present invention is intended to solve the problem of residual stress of a material corrected with a conventional tension leveler, and not only achieves flatness of the material, but also has little residual stress and is easy to use with less deformation in subsequent processing. The aim is to obtain a tension leveler that can correct the material. Furthermore, it is desirable that the tensile force necessary for correction can be reduced as much as possible.

  In order to achieve the above object, the tension leveler of the present invention comprises an entry side bridle roll, an exit side bridle roll, and a pressure unit installed between the two bridles. The pressurizing unit is a device intended to reduce the tensile strength in the longitudinal direction of the material by applying high pressure in a short section over the entire width of the front and back surfaces of the material. The peripheral speed of the exit side bridle roll is slightly larger than the peripheral speed of the input side bridle roll, and there is a difference in peripheral speed between the two bridle rolls. Accordingly, the material wound between the entry side exit side bridle rolls is pulled, and when passing through the pressurizing unit, the material is plastically stretched at a constant stretch rate determined by the peripheral speed difference between the both bridle rolls and corrected. .

  The purpose of the pressurizing unit of the present invention is to perform tension correction without bending the material between the inlet and outlet bridle rolls. When no pressurizing unit was installed, the stretching of the material occurs in a concentrated manner where the tensile strength is the smallest due to the material strength variation from the inlet bridle roll outlet to the outlet bridle roll inlet. Uniform correction over the whole area is not possible. When the pressurizing unit is installed, the material is plastic-stretched as soon as the material enters the center of the pressurizing unit, is corrected at that moment, and is corrected almost uniformly over its entire length as the material progresses. The material is not bent during the straightening process, and the residual stress of the straightened material is small.

  Two cylindrical metal hollow rolls are assembled in the pressure unit so as to sandwich the material. By the mutual pressing of the hollow rolls, the circular cross section perpendicular to the axis of the hollow roll is deformed slightly flat, and the surface of the hollow roll is deformed by the contact pressure with the material to make contact with the material. The material is pressed against the hollow roll with a narrow rectangular contact surface and plastically stretched at the center line position of the hollow roll in combination with the tension of the two bridle rolls to achieve the correction purpose. Plastic stretching is performed until the gradient of the strain (horizontal axis) -stress (vertical axis) curve in the tensile test of the material becomes small and is as close to zero as possible. In steel, since the yield point elongation satisfies this condition, the steel is often stretched at the yield point. The reason why the hollow roll is used as the roll in contact with the material of the pressure unit is the flexibility of the shape of the hollow roll. Since a solid roll has high rigidity and is difficult to deform, even a very small dimensional error between the material and the roll itself causes a large difference in the contact pressure between the material and the roll, and therefore cannot be used for a roll in contact with the material. A backup roll is used when necessary to suppress the bending of the hollow roll.

  The properties of the pressure unit required when straightening a material can be calculated and estimated using plastic theory. That is, the contact stress can be calculated using the Hertz contact theory from the elastic coefficient of the hollow roll cylinder and the material, the diameter of the hollow roll and the size of the rolling force. In the hollow roll, the circular cross-section is deformed slightly flat, and the contact chord width and deformation arc height due to contact can be calculated by local deformation due to Hertz stress. The tensile frictional resistance can be calculated from the strength of the rolling force of the hollow roll and the coefficient of friction between the hollow roll and the material. Here, the tensile frictional resistance is the force that resists the stretching of the material due to the friction between the entrance and exit sides of the hollow roll and the material when the material is pulled between the two bridle rolls and plastically stretched at the center line position of the hollow roll. It is. The lower the value, the easier the material is plastically stretched, so the surface of the hollow roll is forcedly lubricated to reduce tensile frictional resistance. Further, the change in the material width due to the stretching of the material and the contact pressure between the hollow rolls is restrained, and a width restraining force is induced in the material. The tension applied to the material necessary for straightening between the two bridle rolls can be calculated and estimated from the plastic shear stress of the material and the three principal stresses at the straightening position of the material using Mises yield conditions. At the same time, this tension is a function of the thickness and width of the material, the elastic modulus of the hollow roll and the material, the yield point and the work hardening degree of the material, the hollow roll rolling force and its diameter, and the friction coefficient between the hollow roll and the material. The value can be estimated theoretically from the unit specifications and material properties.

  When the proof stress of the material to be corrected is significantly lower than the tensile strength, the material starts to expand in the entry side bridle roll, and the material may slide on the surface of the bridle roll and be damaged. In this case, an entry-side bridle roll and a pair of pressure units are added, and a bridle roll, a pressure unit, a bridle roll, a pressure unit, and a bridle roll are connected in series, and the second bridle roll is a shared bridle roll for the entry and exit sides. If so, this problem can be solved because the tension of the material passing through the two pressure units can be increased in a stepwise manner.

  The residual stress of the material corrected with the tension leveler of the present invention is a value similar to the residual stress of the material corrected with the stretcher leveler, which is evaluated as having the lowest residual stress among various straightening machines. Compared to the leveler, it can be expected that the residual stress is extremely small. That is, the material does not have a bending stress at the correction point, and the pressurizing strength of the pressurizing unit is less than that of a skin pass mill or the like, and there is relatively little friction involved in the material correcting process. The residual stress of the material corrected with the tension leveler of the present invention varies greatly depending on the characteristics of the material to be corrected, the specification of the tension leveler and the operation method, but the compressive stress of 15 to 40 MPa on the material surface and 10 to 20 MPa on the center of the material. Calculated as a tensile stress level. Since the straightening process of the present invention is continuously performed while the material is long, it is highly efficient.

Embodiments of the present invention are shown in FIGS.
FIG. 1 shows a tension leveler according to the present invention, in which a pressure unit 1 is placed between an entry-side bridle roll 5 and an exit-side bridle roll 6 to compress the front and back of the material S, and the material S is compressed on both the entry-and-exit sides. The straightening is performed by pulling between the bridle rolls 5 and 6. The arrow indicates the traveling direction of the material S. Both bridle rolls 5 and 6 are composed of large and small large-diameter bridle rolls 52 and small-diameter bridle rolls 53 to give a strong tensile force to the material S. Since the tensile force is strong before and after the pressurizing unit 1, yielding is caused by bending the material. To avoid the problem, the diameter is increased. The presser roll 51 is installed to apply an initial tension to the material S at the entry side bridle roll 5 and the exit side bridle roll 6. When the material S passes through the pressurizing unit 1, the material S is bent without being bent and is plastically stretched at a constant stretch rate determined by the peripheral speed difference between the entry-side and exit-side bradle rolls 5 and 6.

  The drive systems of both the entry side exit side bradle rolls 5 and 6 are mechanically or electrically connected (although not shown in the drawing), and the tension of the material S is set between the bradle rolls 5 and 6. The power is circulated through. Since the entry-side bridle roll 5 brakes the progress of the material S, the power is returned to the drive system. Since the exit side bridle roll 6 pulls the material S, it consumes power, and most of the consumption is covered by the power returned from the entrance side bridle roll 5, so the drive system supplies less power from the outside. I can drive.

2 and 3 show the pressure unit 1 of the first embodiment. Two cylindrical hollow rolls 3 are incorporated in the pressure unit 1, and the hollow roll 3 is supported by a backup roll 4. Since the upper backup roll chock 12 of the backup roll 4 is pushed by the reduction device 21, FIG. 4 shows the hollow roll 3, and the roll cylinder 31 is composed of an end plate 32 so as to be easily deformed. During operation of the pressurizing unit, the roll drum 31 is slightly flattened and comes into surface contact with the material S. The material S is pressed to be long and the tensile strength in the direction is reduced, and at a center position of the pressurizing unit 1 with a smaller drawing force, the material S is drawn at a constant elongation rate due to the difference in peripheral speed between the entry and exit side bridle rolls, thereby achieving the correction purpose. .
FIG. 4 shows the hollow roll 3, and the roll body 31 is formed of an end plate 32 so as to be hollow and easily deformed.
FIG. 5 shows the backup roll 4, and the roll body 41 is solid and has high rigidity as a whole to back up the hollow roll 3 to prevent bending.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. For example, various changes, improvements, combinations, etc., such as changing the bridle rolls on both the entry and exit sides to other traction devices such as pinch rolls, filling plastics instead of the hub between the barrel and shaft of the hollow roll, etc. Those skilled in the art will appreciate that this is possible.

  Shape defects due to residual internal stress are a problem in television shadow masks and thin food cans to be printed. Since the material processed by the tension leveler of the present invention has low residual stress and good flatness of the material, it is expected to improve the manufacturing process of these products and improve the yield.

  Elevation of tension leveler using pressure unit   Elevation view of pressure unit   AA arrow sectional view of FIG.   Cross section of hollow roll   Elevated view of backup roll

Explanation of symbols

1. Pressurizing unit 3, hollow roll 4, backup roll 5, entry side bridle roll 6, exit side bridle roll 11, stand 12, upper backup roll chock 13, lower backup roll chock 14, hollow roll chock 16, backup roll chock holding plate 17, Hollow roll chock holding plate 18, hollow roll balance cylinder 19, backup roll balance cylinder 20, upper connecting beam 21, roll reduction device 22, lower connecting beam 31, hollow roll barrel 32, hollow roll hub 33, hollow roll bearing 34, hollow roll shaft 41, backup roll 42, backup roll bearing 51, presser roll 52, large-diameter bridle roll 53, small-diameter bridle roll S, material

Claims (2)

  There is an entry-side bridle roll and an exit-side bridle roll whose peripheral speed is slightly higher than the peripheral speed of the entry-side bridle roll, and the strip is not wound between the two bridle rolls by winding the strip around the two bridle rolls. The tension leveler is characterized in that the front and back surfaces of the band plate are pressed by a pair of hollow rolls, and the band plate is plastically stretched and corrected by the difference in peripheral speed between the two bridle rolls.   The tension plater strip according to claim 1, wherein the strip plate is plastically stretched and corrected by controlling the difference in peripheral speed between the entry side bridle roll and the exit side bridle roll and the mutual pressing force of the pair of hollow rolls. Correction method.

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