JPH07275920A - Continuous surface treatment device sequence for metal - Google Patents

Abstract

PURPOSE:To reduce load on spent acid treatment by providing a vacuum treatment chamber in which multi-divided electrodes and a conductor roll are provided in the width direction confronting each other holding the pass line of a material to be treated between them. CONSTITUTION:One or more kinds out of a light draft mill 14, a bending roll 15, a grinder 16, a shot blast 17, dilute acid pickling devices 18-1, 18-2 are arranged on the carrying system of the material to be treated. After the material to be treated is treated, through these equipments, it is introduced to the vacuum treatment chamber 12 through a vacuum control chamber 13-1. The material to be treated is grounded by bringing it into contact with the conductor roll 22 in the vacuum treatment chamber 12, and a high voltage is applied to an electrode 21, and arc-discharge is performed between the material to be treated and the electrode 21, thereby, impurities and scale in the material to be treated are eliminated. After that, it is discharged from the vacuum treatment chamber through a vacuum control chamber 31-2. Thence, one or more kinds of treatment using equipments out of a coil grinder 28, a dilute acid pickling device 29 and a brush roll 30 are applied, then, surface treatment can be completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous metal surface treating apparatus line.

[0002]

2. Description of the Related Art Conventionally, as a descaling method for steel materials,
Mechanical descaling methods such as chemical descaling with acid, shot blasting or brushing or polishing the material surface with a grindstone are known.

In carbon steel, the scale is FeO / F
e ₃ O ₄ / Fe ₂ O ₃ has three layers, and in stainless steel, the scale is made of a strong oxide containing Cr.

Conventionally, descaling of these steel materials has been
This is done by treating with acid, and a process for pollution control such as waste acid treatment was indispensable. On the other hand, for steel materials that are difficult to descale, such as stainless steel, it is necessary to use strong acids such as nitric acid and hydrofluoric acid, and there is no choice but to perform difficult processing such as gas treatment and waste acid treatment that accompany descaling processing. It had been.

Further, according to the conventional pickling, it is particularly difficult to remove the so-called biting scale in which the scale is deeply bitten into the metal base or the scale such as a flaw portion. It had to be reprocessed, which was a factor in increasing costs. On the other hand, when the steel material is descaled by shot blasting, the descaling efficiency is low, and the scale (oxide) is not completely removed. There was a problem such as powder residue.

Japanese Unexamined Patent Publication (Kokai) No. 57-56109 discloses a method of descaling a hot-rolled steel strip by applying an electron beam, a laser beam or a discharge arc to the surface of a steel material to melt and evaporate the scale on the surface of the steel material. A method of causing is disclosed. However, when using this method,
It requires a large amount of electric power and has a problem from the viewpoint of energy saving.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides an energy-saving continuous surface treatment apparatus for steel which can efficiently remove scales on a metal surface by a discharge arc in a vacuum.

[0008]

The features of the present invention are that a light reduction mill, a bending mill,
A multi-divided electrode in which at least one of a roll, a shot blaster, a grinder, and a light pickling device is arranged, and downstream of this, a pass line of the material to be processed is sandwiched and arranged in the width direction of the material to be processed. A continuous metal surface treatment equipment line is characterized in that a vacuum treatment chamber opposite to a conductor roll is provided, and at least one of a coil grinder, a light pickling device, and a brush roll is disposed downstream of the vacuum treatment chamber. is there.

The present invention will be described in detail below. According to the present invention, it is possible to continuously and effectively remove impurities and oxides on the surfaces of strips, wires, pipes, and molds (hereinafter, referred to as a material to be treated) of ferrous or non-ferrous metal.

In the present invention, arc discharge is performed between the material to be processed and the electrodes in a vacuum of 1 to 10 ^-3 Torr to remove impurities and scale on the surface of the material to be processed continuously and efficiently.
The vacuum arc begins with the presence of the scale (metal oxide), and when the scale is removed by the electric shock evaporation action and the metal surface appears, the arc does not fly to the metal surface but moves to the scale part with a small work function. Discharge starts.
With atmospheric pressure discharge or underwater discharge, only one bright spot (arc spot) can be formed on the cathode and the anode, but in vacuum, many very small arc spots are generated on the cathode, and these move around violently and randomly. Is quickly removed.

As a result of repeated studies involving various experiments, the present inventors have found that when vacuum arc discharge is carried out, not only the surface layer of the object to be processed but also the metal oxide or the metal oxide deeply entangled from the surface layer to the metal base material. It has been found that it is possible to efficiently and preferentially remove scales and the like that are generally difficult to remove on the surface flaw. Since the material to be treated has excellent surface properties, it can be used as a product as it is, but the surface properties such as roughness can be freely adjusted by performing multi-electrode treatment.

Next, prior to the vacuum arc discharge, light reduction rolling with 2 to multi-stage rolls and / or repeated bending with bending rolls is added to the material to be treated to positively impart minute cracks and / or shots.・
It was found that the work relationship of the vacuum arc discharge is lowered by performing rough descaling by blasting and / or grinder and further light pickling if necessary, and the vacuum arc discharge is effectively performed with less electric power.

Further, following the vacuum arc discharge, surface conditioning and / or
Alternatively, if a light pickling treatment with a relatively low concentration of sulfuric acid or hydrochloric acid is performed within a few minutes, crater-like irregularities in the scale removal portion that may be formed by vacuum arc discharge or melt solidification with low Cr concentration that has poor corrosion resistance It was found that while removing the layer and similar particles, the surface roughness becomes small and excellent descaling is possible.

When light reduction rolling is applied to the material to be treated, the number of rolls may be two or more, but it is more effective if the diameter of the work roll is as small as possible. Further, the bending roll is also called a roller leveler and has a structure in which 4 to 9 rolls are arranged in a zigzag pattern between the upper and lower rolls and the vertical roll gap can be adjusted. When repeatedly bending the material to be treated by the bending roll, the interval between the upper and lower rolls is changed according to the plate thickness so that the scale on the surface of the material to be treated is effectively cracked.

On the other hand, shot blasting is to remove a scale on the surface of a steel material by projecting a cut wire or steel shot on the surface of a steel material at a high speed of 50 to 60 m / sec by a centrifugal force of an impeller. Of course, wet shot blasting can also be used.

Grinding is a method of removing surface scale or unevenness of a material to be processed by a grindstone rotating at a high speed. As a grinder, the rotating whetstone part can be moved to the front, rear, left and right by hydraulic pressure so that it can be cleaned anywhere on the material surface, and it is used for local flaw maintenance.

In the present invention, the coil grinder uses a belt sander or the like to reduce the surface roughness of the material as it is under vacuum arc descaling (descaling by vacuum arc discharge), and in the case of stainless steel, by vacuum arc descaling. It can also be applied to effectively remove a melt-solidified layer that has a low Cr concentration and may be formed on the surface of steel and has poor corrosion resistance.

The pickling is carried out by immersing in an acid solution such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid or hydrofluoric acid. Generally, inexpensive sulfuric acid is widely used, but hydrochloric acid has an advantage that scale can be quickly removed at room temperature. An inhibitor is added to the pickling solution in order to prevent the life of the pickling solution from increasing and the product from being overpickled.

As a roll which is provided at the outlet of the pickling or electric cleaning line and scrapes off dirt, a brush roll in which a loop of a brush or a fibrous brush is assembled is known. According to the experiment, when the brush roll is incorporated into the apparatus row of the present invention and used together, it is effective for adjusting the surface roughness of high-grade products such as stainless steel, and for example, a mirror finish can be obtained.

[0020]

【Example】

(Embodiment 1) In FIGS. 1 and 5, a vacuum processing chamber 12
Are provided with vacuum adjusting chambers 13-1 and 13-2 on the inlet side and the outlet side, respectively, and are constantly maintained at a pressure (vacuum degree) of 1 to 10 ^-3 Torr. Further, in the vacuum processing chamber 12, an electrode 21 and a conductor roll 22 are provided opposite to each other with a pass line of the material to be processed sandwiched therebetween, and the electrode and the conductor roll are alternately arranged in the traveling direction of the material to be processed. . The electrode 21 is
As shown in FIG. 2, a multi-divided electrode has a structure extending in the width direction of the material to be processed, and a discharge mode is individually and selectively applied to each unit electrode. The discharge mode consists of current, voltage, magnetic field strength, direction, potential difference between the material to be processed and the electrode, and is given in advance by the computer for each material to be processed.

The material 20 (steel strip) to be treated is supplied from the pulling roll 9-1 to the four-stage roll 14, where it is lightly rolled and then introduced into the vacuum treatment chamber 12.
The reduction ratio in the light reduction rolling performed by the four-stage rolls 14 is preferably 0.5% or more. However, the effect of light reduction rolling is saturated at 5%.

1 and 5, reference numeral 26 is a vacuum arc controller, and 27 is a computer. In the computer 27, based on information such as the material of the material to be processed 20, the thickness of the oxide film on the surface, the degree of contamination, the cross-sectional dimension of the material to be processed 20, the strength of the electric current, voltage, magnetic field at the electrodes, The direction and the like are calculated and calculated, and the respective set values are given to the plurality of electrodes individually. These settings are controlled by the controller 26 to maintain their values.
Controlled by.

The processed material 20 processed in the vacuum processing chamber 12 can be directly used as a product. Also,
By using multiple electrodes, it is possible to adjust the surface roughness of the processing target material 20 processed in the vacuum processing chamber 12. Furthermore, in addition to the treatment in the vacuum treatment chamber 12, pickling was performed in a light pickling tank. In the light pickling tank 29-1, the acid treatment was performed within 5 minutes with a sulfuric acid solution having a relatively low concentration (sulfuric acid 300 g / liter).

3 to 4 show a process of smoothing a material to be processed which is processed by the continuous surface processing apparatus train of the present invention.
After the scale 23 of the material 20 to be treated in FIGS. 3 and 4 (a) is cracked by a four-stage roll and / or a bending roll and / or is roughly descaled by shot blasting or the like. (Fig. 3,
4 (b)), the discharge arc is irradiated in the vacuum processing chamber 12, and the primary processing is performed. The scale 23 is removed, and the surface texture level L1 is formed by the density of the discharge arc 25 (FIGS. 3 and 4 (c)). Then, the secondary processing is performed, and the convex portion after descaling is melted and smoothed to the level L2 (FIGS. 3 and 4 (d)). Level L3 by light pickling
To obtain excellent surface roughness.

In the light reduction rolling with the four-stage roll 14, a reduction rate of 0.2% was applied. When the material 20 to be treated is stainless steel (19Cr-0.6Nb steel hot-rolled sheet), the treatment speed is 10 to 50 mpm, but in the present invention, the input power is set to 1 kW · Hr · m ^2. Descaling was complete. It was confirmed that the descaling of areas that are generally difficult to remove, such as surface flaws, was also completed. The surface roughness is Rmax = 12 μm and Ra = 1.5.
μm, and a very excellent surface quality could be obtained. A tank with low Cr concentration and poor corrosion resistance can be completely removed.

As a comparative example, in the process shown in FIG. 5, the material 20 to be processed was directly supplied to the vacuum processing chamber 12 without performing light reduction rolling by four-stage rolls, and descaling was tried. 20 is stainless steel (19
In the case of Cr-0.4Nb steel hot rolled sheet), the input power required for complete descaling was 2.2 kW · Hr / m ² .

Further, in FIG. 5, the material 20 to be processed was directly passed through the light pickling tank 29 without passing through the vacuum processing chamber 12, and in the case of the stainless steel (19Cr-0.6Nb steel hot rolled sheet), Descaling was not complete.

In FIG. 5, the material 20 to be treated is lightly pickled in a bath 29.
If not passed, the surface roughness of the stainless steel is Rma.
x = 13 μm and Ra = 1.6 μm, which are about the same as those of the examples, but the surface properties are inferior to those of the examples because the unevenness is steep and the surface may be uneven when cold-rolled.

(Embodiment 2) Using the apparatus train shown in FIG.
The material 20 to be processed was supplied to the vacuum processing chamber 12 through the bending roll 15 to be subjected to descaling processing, and then passed through the light pickling tank 29.

The bending roll 15 is used for the material 2 to be treated.
0 was repeatedly bent four times, and 200 mR of bending was repeatedly applied to the material to be treated 20 (3.8 mm thick 19Cr-0.6Nb stainless steel hot-rolled sheet). The other processing conditions were the same as in Example 1, but the input power required for complete descaling was 0.9 kW · Hr / m ² . The light pickling condition is a treatment of 300 g / liter of sulfuric acid within 5 minutes. The surface roughness was Rmax = 11 μm, and very excellent surface quality could be obtained.

(Embodiment 3) Using the apparatus row shown in each of FIGS. 7 to 15, the material to be treated 20 is treated by a four-stage roll 14, a bending roll 15, a shot blast 17, a grinder 16 or a pickling device 18. At least one of them was supplied to the vacuum processing chamber 12 and subjected to a descaling process. As a post-treatment, a light pickling tank 29 and a coil grinder 2
8 or at least one of the brush rolls 30 was threaded. The test conditions and test results are summarized in Table 1.

In shot blasting 17, steel shot was projected onto the material to be treated at a high speed of 50 m / sec. Belt-shaped sanders were used for the coil grinders 16 and 28. A brush-like brush was used as the brush roll 30. Other conditions were the same as in Example 1 and Example 2.

The input electric power required for complete descaling is 1 kW · Hr / m in any of the apparatus trains of the present invention.
^{It was} less than ² and the descaling was done very effectively. The surface roughness was evaluated by Rmax, and in Table 1, 10 μ
m and 15 μm or more are indicated by ◯, and less than 10 μm is indicated by ⊚.

[0034]

[Table 1]

[0035]

According to the present invention, after the scale on the surface of the material to be treated is preliminarily cracked or after the rough descaling by mechanical descaling is performed, the treatment for applying the discharge arc is performed in the vacuum treatment chamber 12. Therefore, the input power can be made small and the manufacturing cost can be reduced. The present invention performs overall descaling by vacuum arc discharge and further performs surface conditioning by coil grinding and / or light pickling treatment, so that a product having very excellent surface properties can be obtained.

According to the present invention, since the scale partially buried in the surface of the material to be treated, the scale of the flaw portion, or the residual scale due to mechanical descaling can be effectively removed by the discharge arc, extremely excellent descaling is possible. Therefore, the yield can be dramatically improved and the manufacturing cost can be reduced. Further, compared with the descaling by pickling, the facility construction cost can be reduced, the processing time can be significantly shortened, and the load of waste acid treatment can be significantly reduced.

[Brief description of drawings]

FIG. 1 is an overall explanatory view of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a flow of the present invention.

FIG. 4 is a flow of the present invention.

FIG. 5 is an explanatory diagram of an embodiment sequence of the present invention.

FIG. 6 is an explanatory diagram of an embodiment sequence of the present invention.

FIG. 7 is an explanatory diagram of an embodiment mode of the present invention.

FIG. 8 is an explanatory diagram of an embodiment sequence of the present invention.

FIG. 9 is an explanatory diagram of an embodiment mode of the present invention.

FIG. 10 is an explanatory diagram of an embodiment sequence of the present invention.

FIG. 11 is an explanatory diagram of an embodiment sequence of the present invention.

FIG. 12 is an explanatory diagram of an embodiment sequence of the present invention.

FIG. 13 is an explanatory diagram of an embodiment sequence of the present invention.

FIG. 14 is an explanatory diagram of an embodiment sequence of the present invention.

FIG. 15 is an explanatory diagram of an embodiment sequence of the present invention.

[Explanation of symbols]

 9-1 pulling roll 9-2 pulling roll 9-3 pulling roll 10 payoff reel 12 vacuum processing chamber 13 vacuum adjusting chamber 14 four-stage roll 15 bending roll 16 grinder 17 shot blasting 18 pickling device 20 treated material 21 electrode 22 Conductor Roll 23 Scale 24 Crack 25 Discharge Arc 26 Vacuum Arc Controller 28 Coil Grinder 29 Light Pickling Tank 30 Brush Roll

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Matsuoka 20-1 Shintomi, Futtsu City, Chiba Nippon Steel Co., Ltd. Technology Development Division (72) Inventor Masanobu Horie 2-6-3 Otemachi, Chiyoda-ku, Tokyo Within Nippon Steel Corporation

Claims (1)

[Claims] 1. A light reduction mill, a bending roll, a shot blasting machine, a grinder, a conveying system for the material to be treated.
And at least one of the light pickling devices, and downstream of this, a multi-divided electrode and a conductor roll arranged in the width direction of the material to be processed with the pass line of the material to be processed sandwiched therebetween. A continuous metal surface treatment apparatus line comprising a vacuum processing chamber and at least one of a coil grinder, a light pickling device, and a brush roll disposed downstream of the vacuum processing chamber.