JPH081241A - Straightening device for metallic strip - Google Patents

Abstract

PURPOSE:To obtain a straightening device that does not produce surface flaws. CONSTITUTION:On the upstream side of a leveler 2, a conductive roll 1-1 is arranged of which a metallic strip S comes into contact with the outer periphery in a bent state. One conductive roll 1-1 and a backing-up roll which has a larger diameter than the work roll 2-1 of the leveler 2 and which becomes a conductive roll 1-1 are arranged in a work rool 2-1. It is desirable that a shape measuring device 9 for a metallic strip 5 and a speed indicator 12 for the strip are arranged in the front stage of the conductive roll 1-1 on the upstream side of the straightening device and in the rear stage of the leveler 2, and that a current controller is provided which outputs current in accordance with the output of the shape measuring device 9 and/or the output of the speed indicator 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for straightening a metal strip, and more particularly to a device for straightening and heating a metal strip by a leveler.

[0002]

2. Description of the Related Art In order to correct the shape of a metal strip with a conventional leveler, it is necessary to increase the tension applied to the metal strip or the roll pushing amount. However, when a large tension, a large amount of roll pushing, or the like is applied, the bending of the roll may cause a new shape defect in the metal strip or a non-uniform residual stress in the width direction. In order to prevent the roll from bending, it is necessary to enlarge the leveler, which not only requires a large equipment space, but also increases equipment costs and operating costs.

As a means for enhancing the leveling effect of the leveler, there is a method of increasing the temperature of the metal strip and lowering its deformation resistance to correct it. For example, `` Plasticity and Processing, '' Vol. 29, No. 333, p.
A paper entitled "Development of a new leveler for thick plates" was reported in 1010 to 1015, and the relationship between the temperature of the steel plate and the straightening effect was introduced. This report shows that even if the tension applied to the steel sheet is small, the elongation of the steel sheet increases as the temperature of the steel sheet increases, and it is suggested that the straightening ability increases as the temperature of the steel sheet increases.

However, if the temperature of the metal strip is increased in the atmosphere, a temper color is generated and the quality is deteriorated, which is not preferable. In this case, the maximum heating temperature of the metal strip required for straightening is
Limited by the limit temperature at which the temper color is generated,
In air, it is usually 250 to 300 ℃. However, in order to correct at this temperature, it is necessary to install a heating furnace in the immediate vicinity of the leveler, but since the heating furnace requires large equipment and the thermal inertia is large, in-line temperature control response is poor. However, it is difficult to install in terms of space. If the furnace is installed far from the leveler, even if the metal strip is heated to the maximum temperature, the temperature will drop until it reaches the work roll of the leveler after it is taken out of the furnace and the heating effect will be fully exerted. I can't. On the contrary, if the temperature is higher than the target temperature in order to obtain the target temperature at the leveler, a temper color is generated on the metal strip.

On the other hand, the induction heating device can be installed in the immediate vicinity of the leveler, but the device is complicated and expensive, the heating efficiency is poor, and it is difficult to uniformly heat the plate width direction. Is.

As a method of solving this problem, it is effective to directly heat the metal strip by heating it. For example, Japanese Patent Laid-Open No. 15927/1993 discloses a method for conducting leveling by electrically heating a steel sheet using a work roll of a leveler or a pinch roll outside the leveler as an energizing roll, and an apparatus for carrying out the method. In addition, in the Soviet inventor certificate 361205,
A method of straightening a long material by electrically heating between upper and lower rolls using a leveler work roll as an electrode is disclosed.

[0007]

When the pinch roll is used as the electrode as disclosed in Japanese Patent Laid-Open No. 5-15927,
Since the metal strip makes a line contact with the pinch roll, the contact area is small, and when a large current is applied, a spark may occur between the pinch roll and the metal strip, which damages the metal strip.
If the pinch force (pressing force) is increased in order to prevent this, the metal strip reaches the maximum temperature in the immediate vicinity of the post-stage pinch roll and is rolled, and the plate thickness varies. In addition, since the roll of the pinch roll, which is an energizing roll, is also heated, the temperature of the roll rises during long-term use, causing seizure with the metal band, or deformation due to the thermal crown due to thermal expansion, There is a problem that a gap is partially formed between them and a spark is generated, and the metal strip is damaged.

When the leveler work roll is an energizing roll as disclosed in USSR Inventor No. 361205,
The diameter of the work roll is as small as about 30 mm, the electric resistance of the roll becomes large, and if current is passed from the end of the roll, it will flow mainly through the end of the metal strip, so the metal strip will be heated uniformly in the width direction. I can't.

An object of the present invention is to provide a straightening device capable of uniformly heating a metal strip in the width direction without generating a spark between the metal strip and the current-carrying roll when straightening by direct electrical heating. There is.

[0010]

Means for Solving the Problems The inventors of the present invention have made uniform the heating temperature of a metal strip without causing a spark between the metal strip and the current-carrying roll when straightening by direct electrical heating. The present invention has been completed by recognizing that it is necessary to increase the contact area between the metal strip and the energizing roll and not to deform the energizing roll.

The gist of the present invention resides in the following straightening device shown in FIG. 1 or FIG.

A straightening device for metal strips, in which an energizing roll (1-1) is arranged on the upstream side of the leveler (2) so that the metal strip (S) bends and contacts the outer circumference of the roll. (See Fig. 1) One energizing roll (1-1) described above and leveler
A straightening device for a metal strip, in which a roll (10) having a diameter larger than that of the work roll (2-1) of (2) and also serving as a current-carrying roll and a backup roll of a leveler is arranged.
(Refer to Fig. 2) The straightening device described above consists of a metal band shape measuring instrument (9) and a metal band speedometer (1
2) and are arranged, and it is preferable to include a current control device (11) for outputting the output of the shape measuring instrument and / or the current according to the strip running speed.

[0013]

[Action]

I. Regarding the effect of straightening by electric heating: When straightening with a leveler, the required plastic elongation amount to be given to the metal strip depends on the yield strength (0.2% proof stress) of the metal strip, but usually 0.2-
It is 0.5%.

FIG. 7 is a diagram showing the relationship between the 0.2% proof stress of stainless steel (SUS304) and the temperature. As shown in FIG. 7, the 0.2% proof stress of the metal strip decreases as the temperature rises during heating and straightening. To do. Therefore, at room temperature, an effect equivalent to that of a straightening requiring a large tension can be obtained by heating under a small tension. Even if the material of the shape-corrected material is different, it is possible to change the plastic elongation without changing the pushing amount of the roll, the tension on the exit side, the rolling force, etc. simply by changing the heating temperature. It is also possible to perform straightening.

Joule heat proportional to the square of the flowing current and the electric resistance of the metal strip is generated in the metal strip between the current-carrying rolls. The metal band is rapidly heated by this Joule heat, but the temperature of the metal band can be freely changed and the temperature can be accurately controlled by adjusting the amount of supplied current. It can be straightened at an optimum temperature according to the passing speed and the material.

Therefore, in the case of slight shape correction, the electric current heating is not performed, and it is also possible to raise the temperature instantaneously by the electric current heating in a markedly defective portion or a joint portion such as welding, and continuously correct the shape.

In order to prevent the occurrence of temper color,
Even if the maximum heating temperature is limited, it is one of the levelers.
By using the energizing roll as the work roll in the step, it is possible to correct the work at the maximum heating temperature.

II. Regarding the current-carrying roll: The current-carrying roll of the straightening device of the present invention is configured so as to be in surface contact with the metal strip and electrically connected thereto. The leveler work roll is an energizing roll.

FIG. 5 is a view showing a state in which the energizing roll is in surface contact with the metal strip, and the diameter of the energizing roll 1-1,
The contact arc length is determined by the distance (roll pitch) between the energizing roll and the pressing roll 1-2, the pushing amount of the pressing roll and the tension. Here, "to make surface contact" electrically means
It means a surface contact to the extent that no spark is generated when energized. For example, as shown in FIG. 6 described later, a value obtained by dividing the total input current by the contact area corresponding to the contact arc length (feed current density). Is to be contacted in an area of 300 A / mm ² or less.

The work roll of the leveler may be an energizing roll as shown in FIG. 3 described later. However, in the case of a large-capacity device, as shown in FIG. 2, a roll having a diameter larger than that of the work roll, which doubles as a current-carrying roll and a backup roll of the leveler, is arranged, and a current is passed through this roll. You can also drain.

III. Regarding the straightening device: The straightening device of the present invention using direct electric heating includes, for example, a device having the following configuration.

1. Straightening device having an energizing roll having a pressing roll: Fig. 1 is a diagram showing a straightening line in which an energizing roll having a pair of pressing rolls is arranged in the preceding stage of a leveler, and 1-1 is a pressing roll 1-2. Energizing rolls,
2 is a leveler, 3 is a power source, 5 is a payoff reel, 6 is a tension reel, 7 is a tensiometer, 8 is a thermometer, 9 is a shape measuring instrument, 12 is a speedometer, and S is a metal strip.

The metal strip S is bent by a pressing roll 1-2 provided in front of the energizing roll 1-1 and brought into surface contact with the energizing roll. It is preferable that the two energizing rolls are made large in order to raise the heating temperature, and the energizing rolls in the subsequent stage and the leveler first-stage work rolls are as close to each other as possible in order to prevent a temperature decrease.

According to this heating device, the metal strip is bent and brought into contact with the current-carrying roll by the pressing roll and comes into surface contact, so that it is possible to prevent the occurrence of sparks during power-on. In addition, the correction ability can be improved simply by adding it to the front stage of the existing leveler equipment.

2. An energizing roll with a pressure roll,
A straightening device having a roll that doubles as a backup roll and a current-carrying roll of a leveler work roll: FIG. 2 shows a heating device that includes a current-carrying roll having a pressing roll and a roll that also serves as a backup roll and a current-carrying roll of a leveler work roll. It is a figure which shows the correction line provided with. 1-1 is an energizing roll having a pressing roll 1-2, 2-1 is a leveler work roll having a diameter of 30 mm, 10 is a work roll 2-1.
A backup roll (for example, a diameter of 80 mm) that energizes while rotating and supporting, a metal strip shape measuring instrument, and a current control device.

The work roll of the leveler may be an energizing roll as shown in FIG. 3 described later. In this case, since the diameter of the work roll is small, if current is applied from both ends of the roll, the current density becomes uneven, and the metal strip may not be uniformly heated in the width direction. Therefore, as shown in FIG. 2, by arranging a roll 10 having a diameter larger than that of the work roll 2-1 and also serving as an energizing roll and a backup roll of a leveler, an electric current is passed through this roll. It is possible to raise the temperature of the metal strip uniformly.

In FIG. 2, the leveler work roll of the first step is supported by the energizing roll and the backup roll.
You may support the work roll of the 2nd step or later.

3. A straightening device in which a bridle roll to be a current-carrying roll and a work roll to be a current-carrying roll are arranged in the leveler: FIG. 3 shows a bridle roll to be a current-carrying roll in the previous stage of the leveler and a work roll to be a current-carrying roll in the leveler. It is a figure which shows the corrective device which did. 4 is a bridle roll. As shown in the figure, since the bridle roll 4 is an energizing roll, the contact area with the metal strip is larger than that of an energizing roll having a pressing roll, and stable energization heating is possible.

In FIG. 3, the work roll on the first stage of the leveler is the energizing roll, but the rolls on and after the second stage may be energizing rolls.

4. A straightening device having a bridle roll serving as a current-carrying roll and a current-carrying roll having a press roll: FIG. FIG. If there is a problem with insulation etc. and the work roll of the leveler cannot be used as the energizing roll, the energizing roll 1-1 having the bridle roll 4 and the pressing roll 1-2, which are the energizing rolls, is provided in the preceding stage of the leveler. It is something that is done.

[0031]

EXAMPLES The present invention will be described in more detail by way of examples.
The evaluation of the present invention was conducted on the fact that no spark was generated, that uniform heating was possible, and that shape correction was possible.

FIG. 8 is an exaggerated view of the shape defect of the metal band before being corrected, and the peak height H of the ear wave was measured as an index for confirming the effect of the correction.

[Example 1] In the straightening line shown in Fig. 1, the stainless steel plate was used, and the metal strip (steel plate) shown in Fig. 5 was used.
The plate thickness, the diameter of the energizing roll, the roll pitch, and the pressing amount of the pressing roll were changed as shown in Table 1, and a straightening test was performed. The applied current is changed stepwise from 1kA to 6.5kA, and the energization interval (distance between centers of energizing rolls) is changed.
It was set to 500 mm and was run at a plate passing speed of 1 m / s.

[0034]

[Table 1]

The leveler 2 is a non-driving type and has a diameter of 30.
It consists of 5 work rolls 2-1 each having a length of mm and a barrel length of 300 mm, which are arranged in parallel at intervals of 20 mm. The roll pushing amount with the leveler was 1 mm, and the entry side tension was 6 kgf / mm ² .

There are two kinds of energizing rolls having a diameter of 30 mm and 100 mm and a barrel length of 400 mm, and the pressing roll has a diameter of 200 mm and a barrel length of 400 mm.

The material to be straightened is a stainless steel (SUS 304) coil with a plate thickness of 0.45 mm and 1.00 mm and a plate width of 100 mm. The shape before straightening is the average value of the peak height H of the ear wave shown in FIG. I used the one of 5 mm.

FIG. 6 is a diagram showing the relationship between the energizing current density and the making current, which influence the generation of sparks obtained by the above test. When the material temperature reached 300 ° C., the presence or absence of sparks was observed, and those without sparks are indicated by ◯, and those with sparks are indicated by ● in FIG. As is clear from the figure, the energization current density is
If it is 300 A / mm ² or less, no spark is generated and stable energization is performed.

Table 2 shows the results of straightening under the conditions of Test No. 5 shown in Table 1 while keeping the steel plate temperature on the leveler entrance side at room temperature, 100 ° C, 200 ° C and 300 ° C. The higher the correction temperature, the smaller the peak height of the ear wave after correction and the higher the correction ability.

[0040]

[Table 2]

[Embodiment 2] Using a straightening line (energization interval of 500 mm) as shown in FIG. 2 described above, the energization roll / backup roll 10 of the first stage work roll 2-1 of the leveler 2 is released to It is possible to directly energize the roll 2-1 and use the energizing roll shown in No. 5 of Table 1 of Example 1 at 4 kA.
It was energized and heated with the current of.

Since the metal strip on the first-stage work roll is pushed in by the second-stage work roll, the metal strip bends and comes into contact with the work roll, and comes into surface contact. Therefore, the same effect as in Example 1 is obtained. Is obtained. However, when the central part of the metal strip was heated to 300 ° C, the thermal crown caused
A spark has occurred.

FIG. 9 is a diagram showing the temperature distribution of the metal strip obtained during the above-mentioned electric heating. The temperature at both ends of the metal strip is about 70 ° C higher than at the center, as shown by "energization only by the work roll" in the figure.

As shown in FIG. 2, the work roll 2-1 (diameter 30 mm) was electrified (energization interval 500 mm) through the energization roll / backup roll 10 (diameter 80 mm) to perform straightening. As a result, no spark was generated, and the temperature difference between the both ends and the central portion of the metal strip was small, as indicated by "energization by the work roll through the backup roll" in FIG.

[Embodiment 3] Using the straightening line shown in FIG. 2 (the specific structure is the same as that of Embodiment 2), the height of the peaks of the spikes is changed in advance in three steps (SUS 30
4, plate thickness 1 mm, plate width 150 mm, length 25 m) was run at 1 m / s. The peak height of the ear wave obtained by the shape measuring instrument 9 and the output of the thermometer 8 were input to the current control device 11 to correct the current while controlling the current according to the peak height of the ear wave.

FIG. 10 is a diagram showing the peak heights of the ear waves before and after the correction and the changes in the applied current during the correction obtained in the above test. When the making current is controlled as shown in (a) by the output of the shape measuring instrument and the thermometer, the metal strip shows the curve shown as "the height of the spike wave peak after correction when the making current is controlled as shown in (a)". As can be seen, the shape is effectively corrected.

As a comparison, the test was conducted also when the making current was kept constant at 5.0 kA, and the results are shown in FIG. Keeping the applied current constant does not mean that the level of the ear wave height before correction is lowered, as indicated by the curve shown as "the height of the ear wave peak after correction when the applied current is controlled at 5.0 kA." , I cannot expect a perfect flatness correction.

Further, since the leveler is often provided in the preceding stage of the inspection line and the strip passing speed often fluctuates,
A test was carried out while varying the threading speed.

FIG. 11 is a diagram showing the applied current and the temperature of the metal strip when the strip running speed is changed during straightening. When the stripping speed becomes low at the (Z) point, if the making current is made constant like (X), the metal strip is overheated and the temperature rises as shown in (x), and the temper color is generated. Finally, it breaks. However, if the applied current is controlled so as to decrease according to the strip passing speed as in (Y), the temperature can be kept constant as in (y).

From these results, even if metal strips having different plate thickness, material, flat shape, etc. continuously enter the straightening line, it is possible to always straighten them into a constant shape by operating the current control device. is there. Further, even if the strip running speed changes during the straightening, the occurrence of temper color and breakage can be prevented.

[0051]

According to the straightening device of the present invention, since the metal strip and the current-carrying roll are in surface contact with each other, no spark is generated and the metal strip is not scratched. Further, by feeding the work roll of the leveler through the backup roll, it is possible to apply a uniform current in the width direction of the metal strip and uniformly heat the metal strip.

Even if the first stage work roll of the leveler is electrically heated, the temperature responsiveness becomes faster, and even if there is a change in the shape of the metal strip or a welded joint, or metal strips of different materials continuously enter the leveler. Shape can be corrected simply by changing the heating temperature. In addition, by using a current control device, it is possible to perform energization heating according to the degree of shape defect, it is possible to always correct to a constant shape, and to heat to a uniform temperature even if the strip running speed changes. , The occurrence of temper color,
Breaking can be prevented.

Further, it is possible to perform proper shape correction only by changing the heating current while keeping the pushing amount and tension of the leveler constant.

Since the device of the present invention can be used as a normal leveler if the energization is stopped, the energization is stopped in the case of a lightly defective material, and the current is heated only in the case of a severe condition to correct it. The cost can be reduced and the mild to severe shape defects can be efficiently corrected.

The correction device of the present invention can be installed not only newly but can also be constructed by modifying the existing correction device.

[Brief description of drawings]

FIG. 1 is a view showing a straightening line in which a pair of energizing rolls having a pressing roll is arranged.

FIG. 2 is a view showing a straightening line in which an energizing roll having a pressing roll and a roll serving both as an energizing roll and a backup roll are arranged.

FIG. 3 is a view showing a straightening device using a bridle roll and a leveler work roll as energizing rolls.

FIG. 4 is a view showing a straightening device in which an energizing roll of a bridle roll and an energizing roll having a pressing roll are arranged.

FIG. 5 is a diagram showing a state in which an energizing roll is in surface contact with a metal strip.

FIG. 6 is a diagram showing a relationship between an applied current and an energized current density when energized and heated in a state of surface contact.

FIG. 7 is a diagram showing the relationship between the temperature and 0.2% proof stress when stainless steel is heated.

FIG. 8 is a diagram showing a defective shape of a metal strip.

FIG. 9 is a diagram showing a temperature distribution of a metal band when a work roll is energized and when a work roll is energized.

FIG. 10 is a diagram showing a temperature of a metal band and a height of a peak of a wave when a conduction current is controlled.

FIG. 11 is a diagram showing a change in metal band temperature when the strip running speed changes.

[Explanation of symbols]

1-1. Energizing roll 1-2. Press roll
2. Leveler 2-1. Work roll 3. Power supply
4. Bridle roll 5. Payoff reel 6. Tension reel
7. Tensiometer 8. Thermometer 9. Shape measuring instrument 1
0. Backup roll 11. Current control device 12. Speedometer

Claims (3)

[Claims] 1. A straightening device for a metal strip, wherein an energizing roll is arranged on the upstream side of the leveler so that the metal strip bends and contacts the outer periphery of the roll. 2. A current-carrying roll, which is arranged on the upstream side of the leveler and has a metal band bent and in contact with the outer periphery of the roll, and a roll having a diameter larger than that of the work roll of the leveler. A straightening device for metal strips, in which double rolls are arranged. 3. A metal strip shape measuring instrument and a metal strip speedometer are arranged in the upstream of the upstream energizing roll and in the latter stage of the leveler, and an electric current corresponding to the output of the shape measuring instrument and / or the strip running speed is supplied. 3. A current control device for outputting the current control device.
The straightening device for a metal strip according to.