JPH0515927A - Method and device for leveling metal plate - Google Patents

Abstract

PURPOSE:To level a metal plate under a heated state. CONSTITUTION:The metal plate S between work rolls 2-1, 2-4 of a leveler is energized and heated with the rolls 2-1 and 2-4 as electrodes to carry out leveling. More than two work rolls in the leveler can be selected arbitrarily as the electrodes. Further, pinch rolls mounted on the outside of the leveler may be used as the electrodes. The metal plate may be heated and heattreated before and after leveling it. The metal plate is heated by Joule heat between the rolls to be electrodes. Since the metal plate is leveled under a high temperature state small in resistance to deformation, straightening effect is large. The temperature control is easy and the equipment is comparatively simple and compact.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for leveling a metal plate such as a hot-rolled steel plate or a cold-rolled steel plate having a relatively large plate thickness, and particularly to a device for leveling by directly energizing and heating a metal plate.
Alternatively, the present invention relates to a method of performing leveling and heat treatment and an apparatus for carrying out the method.

[0002]

2. Description of the Related Art Roller levelers and tension levelers are widely used as shape correcting devices for rolled metal sheets. A roller leveler is a roll that is arranged in a zigzag pattern at the top and bottom, and a metal plate is passed between the rolls to repeatedly bend it to correct the shape. To correct the Hereinafter, these are simply referred to as levelers.

When correcting the shape of a metal plate (warp, ear wave, middle elongation, etc.) with a leveler, there is a method of imparting a large tension or reduction amount to the metal plate for leveling in order to enhance the correction effect. However, a large leveler is required to apply a large amount of tension or reduction to the metal plate, which not only requires a large equipment space, but also increases equipment costs and operating costs.

As another method for enhancing the correction effect,
There is a method in which the temperature of the metal plate is raised and the deformation resistance is lowered to perform leveling. For example, in “Plasticity and Processing” Vol. 29, No. 333
On pages 1010 to 1015, a research report entitled "Development of a new type leveler for thick plates" is published, and a method for leveling by raising the temperature of a metal plate is introduced in the report. This research report indicates that the elongation of the metal plate increases as the temperature of the metal plate increases even if the tension applied to the metal plate is low. Therefore, by raising the temperature of the metal plate and performing leveling in this way, a leveler that can operate with low tension,
That is, it is possible to use a leveler that can be operated in a small space and at low equipment cost.

In order to level the metal plate in a heated state, a method of leveling the metal plate before winding it in a hot rolling line, or a method of reheating the metal plate in an offline batch type heating furnace to perform leveling is considered. To be However, in the metal plate of the hot rolling line, there is a temperature difference between the center and the plate end in the plate width direction. When leveling a metal plate having such a temperature difference, the metal plate becomes apparently flat, but after the metal plate is cut by a shear or punched by a press, residual stress is released and the metal plate is cut or punched. There is a problem in that the warped member is warped. On the other hand, in order to heat a metal plate off-line, there is a problem that a new heating furnace or the like is required and the temperature of the metal plate is lowered by the time of leveling, and a sufficient straightening effect cannot be obtained. . A method of heating a metal plate by induction heating online is also conceivable, but the induction heating device is complicated and expensive, and the heating efficiency is poor. There is also a problem that the temperature is lowered after the heating device is discharged and before reaching the work roll of the leveler.

[0006]

In the recent labor saving and automation, the metal plate as a material is required to have not only apparent flatness but also residual stress. If there is residual stress, when the metal plate is cut or punched, the residual stress is released and warpage occurs. If such a member is used, a transport trouble may occur in a product manufacturing line, a gap may be generated during welding, a welding defect may occur, and welding man-hours may increase. When the leveling is performed using the temperature of the hot rolled material in the hot rolling line, the above-mentioned problem due to the residual stress occurs, while when the leveling is performed by heating offline, the equipment space and equipment as described above are used. Not only is there a cost problem, but it is difficult to maintain a temperature suitable for leveling. An object of the present invention is to provide a method and an apparatus for uniformly heating a metal plate to an appropriate arbitrary temperature on a leveling line without using an offline heating furnace and performing leveling with a high straightening effect. It is in.

[0007]

According to the present invention, a work roll (leveler roll) such as a roller leveler or a tension leveler or a pinch roll provided outside the leveler is used as an electrode, and a metal plate to be straightened is directly energized. It was made based on the finding that efficient and easy heating can be performed easily and accurate temperature control is possible.

The leveling method of the present invention is characterized in that "a leveler work roll or / and a pinch roll outside the leveler is used as an electrode to energize and heat a metal plate to perform leveling, heat treatment before and after leveling, or both". To do.

The structure of the apparatus for carrying out this method is as follows:
Since it depends on the selection of the roll used as the electrode, it will be described below with reference to the drawings.

(1) A leveling device having at least two work rolls serving as electrodes in a leveler (FIG. 1).

In FIG. 1, S is a metal plate whose shape is to be corrected and is corrected by the leveler 1 while being fed in the direction of the arrow. Leveler 1 has many work rolls 2-1, 2-2,
2-3 ... 2-n, the metal plate S is repeatedly bent during that time and its shape is corrected.

Although not shown, tension rolls for applying tension to the metal plate S may be provided before and after the leveler.

In the apparatus of FIG. 1, the work roll in the leveler is
The electrodes 2-1 and 2-4 are connected to the power source 3. In this case, the intermediate work rolls 2-2 and 2-3 must be insulated from the stand. The power supply 3 may be alternating current or direct current. In this state, the metal plate S is directly energized to generate Joule heat between the work rolls 2-1 and 2-4 to raise the temperature. The work roll used as the electrode is not limited to that shown in the figure. One or more rolls can be selected using any two electrodes in the leveler as an electrode pair.

(2) A leveling device having a pinch roll serving as an electrode in front of the entrance side of the leveler and at least one work roll serving as an electrode in the leveler (FIG. 2)
.

In the apparatus shown in FIG. 2, a pinch roll 4 serving as an electrode is placed in front of the entrance side of the leveler (upstream side).
The electrode paired with the pinch roll is 2-4 here, but it may be any work roll in the leveler. In addition to these electrode roll pairs, additional heating of the metal plate may be performed using another two or more work rolls in the leveler as electrodes, as indicated by a broken line in the figure.

(3) A leveling device having at least one pair of pinch rolls serving as electrodes in front of the entrance side of the leveler (FIG. 3).

The apparatus shown in FIG. 3 has a pair of pinch rolls 4-1 and 4-2 serving as electrodes in front of the inlet side (upstream side) of the leveler. In this apparatus, the metal plate S is electrically heated between these pinch rolls. Pinch roll 4-2 should be installed as close as possible to leveler 1. If the metal plate S is sufficiently heated here, the leveling can be performed at a high temperature. The metal plate in contact with the work roll of the leveler is removed from the heat and the temperature drops.Therefore, in order to compensate for this, the work roll, for example 2-4 and 2-8 in the work roll, is used as an electrode between them. The metal plate may be heated again by applying electricity.

(4) A leveling device having at least one work roll which is an electrode in the leveler and a pinch roll which is an electrode behind the leveler exit side (FIG. 4).

The apparatus shown in FIG. 4 is located after the leveler exit side (downstream side).
The pinch roll 4 serving as an electrode is placed on the other side, and any work roll in the leveler is used as the other electrode.
In FIG. 4, the work roll 2-n closest to the outlet side is used as an electrode. However, when this is done, the leveling itself becomes normal cold leveling, and the metal plate that has undergone leveling is heated by energization and subjected to heat treatment. . In addition, heat treatment means
Here, it mainly means heating for removing residual stress and improving metallurgical properties of the metal plate.

Also in the apparatus of FIG. 4, if the work rolls used as electrodes are replaced with 2-n work rolls on the more upstream side,
Leveling can also be done at high temperatures. If necessary, the metal plate can be electrically heated in the leveler using the work rolls (for example, 2-4 and 2-8) in the leveler as electrodes, as shown by the broken line.

(5) A leveling device having at least one pair of pinch rolls which serve as electrodes behind the output side of the leveler
(Figure 5).

The device shown in FIG. 5 is opposite to the device shown in FIG.
It is a combination of 4-1 and 4-2. These pinch rolls are used for electrical heating for heat treatment of the leveled metal plate S. However, again, as shown by the broken line,
It is also possible to carry out leveling at a high temperature by electrically heating a metal plate in the leveler using work rolls (for example, 2-4 and 2-8) in the leveler as electrodes.

(6) Leveling device having pinch rolls as electrodes before the entrance side and after the exit side of the leveler (FIG. 6)
.

As shown in FIG. 6, it is an apparatus in which pinch rolls 4-1 and 4-2 serving as electrodes are placed in front of and behind the leveler 1. In this apparatus, the metal plate is electrically heated between both pinch rolls, so that the leveling is always performed at a high temperature.
However, there is a somewhat unfavorable aspect in terms of equipment, in which all leveler work rolls must be insulated from the stand.

(7) A metal plate leveling device having pinch rolls as electrodes before and after the entrance and exit sides of the leveler, and further having work rolls in the leveler as electrodes paired with these pinch rolls. [FIG. 7] FIG. 7 shows pinch rolls 4-1 serving as electrodes before and after the leveler 1.
And 4-2 and place them and leveler work rolls (eg
2-1 and 2-n) are paired and electrically heated. In this apparatus, leveling can be performed at a high temperature, and heat treatment before and after leveling can be effectively performed.

[0026]

The leveling method of the present invention is characterized in that the roll in contact with the metal plate is used as an electrode to directly energize the metal plate to heat it. When the work roll in the leveler is used as an electrode as shown in FIGS. 1 to 7, a space for placing a heating device is not required.

Further, even when a pinch roll is placed outside the leveler, the roll only needs to be sandwiched so as to make uniform contact with the width direction of the metal plate.
A roll with a small diameter of about 200 mm is enough, and the equipment is very simple and small. Compared to installing a heating furnace off-line or installing an induction heating device in a straightening line, the cost of manufacturing equipment is much lower, and it is advantageous in terms of space saving. When the work roll of the leveler is used as one of the electrodes, the temperature of the metal plate reaches the maximum value when it reaches the work roll, so extra cooling is required in consideration of the cooling during the transfer process as in the heating furnace method. It is not necessary to keep it heated.

Generally, it is difficult to electrically insulate a rotating roll or the like. For example, in the device shown in FIG. 7, a pinch roll is used.
It is possible to insulate 4-1 and 4-2 and use the leveler work roll as it is (in the non-insulated state). Since the pinch roll may be of the simple non-driving type as described above, its insulation is easy. The power supply to the roll can be performed using a brush made of copper or the like.

Joule heat, which is proportional to the product of the square of the flowing current and the resistance of the metal plate, is generated in the metal plate between the rolls serving as the electrodes. This Joule heat causes the temperature of the metal plate to rise rapidly. Since the temperature can be freely and accurately controlled by adjusting the supplied current, it is possible to carry out the leveling and the heat treatment by selecting the optimum temperature according to the material of the metal plate and the like. Almost no non-uniformity of temperature in the width direction of the metal plate occurs.

In the electric heating type leveling of the present invention, the residual stress generated in the metal plate after leveling is extremely small. Further, in the apparatus as shown in FIGS. 4 to 7, it is possible to heat the metal plate after the leveling to almost eliminate the residual stress.

The method of the present invention can be applied to the leveling of all kinds of metal plates such as carbon steel, low alloy steel, steel plate such as stainless steel, titanium plate, titanium alloy plate, etc. which easily generate resistance heat when energized.

[0032]

EXAMPLE The method of the present invention was carried out using a test leveler having five work rolls shown in FIG.

In FIG. 8, the metal plate S is leveled by the work rolls 2-1 to 2-5 while being driven by the entrance side pinch roll 5 and the exit side pinch roll 6 and moving in the direction of the arrow. In the embodiment, the work rolls 2-1 and 2-5 are connected to the power source 3
To be an electrode. The work rolls 2-1 to 2-4 are electrically insulated from the housing 4. Leveler roll 2-5 on the outgoing side is not insulated. When the metal plate S is passed through the leveler and brought into contact with the work rolls and simultaneously energized, a current flows through the metal plate S between the work rolls 2-1 and 2-5 and is heated by Joule heat.

FIG. 9 is a view showing the state of the metal plate before being leveled by exaggerating the defective shape. The peak height H of the ear wave was measured as an index for confirming the effect of leveling.
A stainless steel plate (JISSUS 304) was leveled using the electric heating leveler of FIG. The main specifications and correction conditions of the leveler are as follows.

A. Number of leveler work rolls ・ ・ ・ ・ 5 rolls of leveler work roll D ・ ・ ・ ・ ・ ・ 30 mm Leveler work roll pitch ・ ・ ・ 40 mm Drive system ・ ・ ・ ・ ・ ・ Pinch roll drive B Metal plate (material to be straightened) Material: JIS SUS 304 Dimensions: Plate thickness 1 mm x Plate width 150 mm Shape (before leveling) Average value of H = 5 mm of ear wave C. Straightening condition Heating method ・ ・ ・ ・ ・ ・ Leveler heating between work rolls Distance between energizing rolls L ・ ・ ・ 120 mm Power supply ・ ・ ・ ・ ・ ・ ・ ・ 60Hz , 5V, 2000 A Heating temperature ・ ・ ・ ・ ・ ・ in front of work rolls 2-5 650
℃ Stripping speed ・ ・ ・ ・ ・ ・ ・ ・ 0.5 m / min Reduction amount ・ ・ ・ ・ ・ ・ For sheet thickness comparison, the above-mentioned specifications are kept at room temperature without heating the material to be straightened. We also conducted a leveling test and a leveling test of the above specifications immediately after heating the material to be straightened to 700 ° C in an offline heating furnace. The results are shown in Table 1.

[0036]

[Table 1]

As is clear from Table 1, when leveling is performed by the electric heating method of the present invention, straightening is performed at 650 to 620 ° C.
The metal plate became almost flat because the deformation resistance was small at high temperature. However, when leveling is performed at room temperature, the stainless steel has a large deformation resistance, so that it is hardly corrected.

The leveling after heating in an off-line heating furnace is not sufficiently corrected. In this case, the temperature of the metal plate is lowered by heat removal by the transport roll and the work roll of the leveler despite heating to 700 ° C., and the effect of heating and leveling is not sufficiently achieved.

The temperature deviation in the plate width direction of the metal plate during the electric heating leveling of the present invention was 7 ° C. or less between the center and the edge of the plate width.

[0040]

The present invention provides a novel leveling method for directly energizing a metal plate to heat it for leveling, and an apparatus for carrying out the method. In this leveling method, since rapid heating can be performed uniformly and immediately before leveling or at the same time as leveling with an optimum heating pattern, heat removal by the transport roll and the leveler roll is extremely small, and the deformation resistance of the metal plate can be effectively reduced. Therefore, the leveling ability of this leveling method is extremely high, and since the heat treatment can be carried out at the same time, the residual stress of the metal plate after leveling is small. Furthermore, compared with the method of leveling after heating in an off-line heating furnace etc., the heating temperature can be controlled more easily, heat loss is less, energy is saved, leveling work is facilitated, and the shape quality of the metal plate is improved. Can be improved. The device of the invention is compact and does not require a large space.

[Brief description of drawings]

FIG. 1 is a side view of a leveling device of the present invention in which two work rolls in a leveler are used as electrodes.

FIG. 2 is a side view of the leveling device of the present invention in which a pinch roll before the entrance side of the leveler and one work roll in the leveler are used as electrodes.

FIG. 3 is a side view of the leveling device of the present invention having a pair of pinch rolls serving as electrodes in front of the entrance side of the leveler.

FIG. 4 is a side view of the leveling device of the present invention in which one work roll in the leveler and a pinch roll after the leveler exit side are used as electrodes.

FIG. 5 is a side view of the leveling device of the present invention having a pair of pinch rolls that serve as electrodes behind the output side of the leveler.

FIG. 6 is a side view of the leveling device of the present invention having pinch rolls as electrodes before the entrance side and after the exit side of the leveler.

FIG. 7 is a side view of the leveling device of the present invention which has pinch rolls as electrodes before and after the inlet side of the leveler and further has work rolls in the leveler as electrodes paired with these pinch rolls. It is a figure.

FIG. 8 is a side view of the leveler tester used in the examples of the present invention.

FIG. 9 is a diagram illustrating a shape defect (ear wave) of a metal plate.

Claims (8)

[Claims] 1. A method for leveling a metal plate, which comprises applying a work roll of a leveler and / or a pinch roll outside a leveler as an electrode to energize and heat a metal plate to perform leveling, heat treatment before and after leveling, or both. . 2. A leveling device for a metal plate, which has at least two work rolls to serve as electrodes in a leveler, and performs leveling by electrically heating the metal plate between them. 3. A pinch roll serving as an electrode in front of the entrance side of the leveler, and at least one serving as an electrode in the leveler.
A metal plate leveling device which has book work rolls and conducts leveling by electrically heating a metal plate between them. 4. A leveling device for a metal plate, which has at least one pair of pinch rolls in front of the entry side of the leveler and serves as electrodes, and which levels the metal plate heated by electric current between them. 5. At least one of which is an electrode in the leveler.
A leveling device for a metal plate, which has a work roll of a book and a pinch roll behind the leveler output side and serves as an electrode, for conducting leveling and / or heat treatment by electrically heating the metal plate between them. 6. A leveling device which has at least one pair of pinch rolls which serve as electrodes after the output side of the leveler, and which heats the metal plate after leveling with the leveler by energizing heating. 7. A leveling device for a metal plate, which has pinch rolls as electrodes before and after the entrance side of a leveler and which serves as electrodes, and performs leveling by electrically heating a metal plate between the pinch rolls. 8. A leveling device for a metal plate, comprising pinch rolls serving as electrodes before and after the entrance and exit sides of the leveler, and further having work rolls in the leveler serving as electrodes paired with these pinch rolls.