JPH05228839A - Hot finished metal band without surface flaw and processing method thereof - Google Patents

Abstract

(57) [Summary] [Object] The present invention improves the surface quality of a strip-shaped metal body by applying blasting with ultra-high pressure water when removing the surface scale and surface flaws of the strip-shaped metal body. In the treatment process incorporating this, there is provided a hot finishing metal strip treatment method which simplifies the pickling treatment and the surface flaw removal process and improves the efficiency of the treatment work. [Structure] The surface layer portion of the metal band having a scale on the surface is cleaned with ultra-high pressure water with or without abrasives mixed, and the surface flaw residual rate is 5% or less without surface flaws. The point is to obtain a metal strip. The projection pressure of the above ultra-high pressure water on the metal strip is at least 1500 kgf / cm ² , and the projection angle is 5 to 75.
And the size of the abrasive material to 40 °
The surface quality of the strip-shaped metal body is improved by cleaning the surface as 400, and the present invention is further inlined to simplify the process and enhance the processing work efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-finished metal strip having no surface flaw and a method for treating the same. In particular,
A band-shaped metal that enables surface quality and surface flaws generated in the hot rolling process and thin cast continuous casting process to be removed by applying ultra-high pressure water to improve the surface quality of metal bands and simplify the treatment process. It relates to a method of treating the body. In the present invention, the hot-finished metal strip (or simply metal strip) means a hot strip (plate) or coil made of stainless steel, ordinary steel, titanium and its alloys, high alloys, etc. by a usual method, or a thin wall. A strip (plate) manufactured by continuous casting or a coil wound up. Moreover, these may be called a strip-shaped metal body.

[0002]

2. Description of the Related Art In the process of manufacturing a hot finishing metal strip,
Oxide scale and surface flaws are generated on the surface of the metal strip due to heating of the slab and subsequent hot rolling, continuous casting of thin slabs, and the like, and therefore it is necessary to remove these and finish the surface. Conventionally, these methods include shot blasting in which a steel ball with a diameter of 0.2 to 0.6 mm is projected on the surface of a strip-shaped metal body to perform surface layer cleaning to cause cracks and peeling of the scale, and then the nitrous oxide. Descale by pickling with acid, sulfuric acid, hydrochloric acid, etc., then perform cold rolling to correct the shape of the strip-shaped metal body, and then remove the surface flaws of the strip-shaped metal body by belt grinding on another line to gauge. It has been considered that a typical method is to use cold rolling for down.

However, in this conventional process, the pickling process is a continuous line with the annealing process, and the grinding line and the rolling line or the dummy plate (hereinafter referred to as a leader) welding line are arranged separately, so that the strip-shaped metal is formed. In order to remove oxide scales and surface flaws on the body, it is necessary to pass 2 to 4 lines, and there is a problem that the efficiency is extremely poor.
The annealing pickling line is inefficient because descaling is performed by pickling, and there are various problems from the viewpoint of productivity, cost and labor saving such as generation of a large amount of waste liquid due to pickling. .. On the other hand, in order to uniformly remove surface flaws by belt grinding in the plate width direction, it is necessary to straighten the shape of the coil by cold working, but this straightening work is performed using a normal cold rolling mill. Therefore, in addition to the original gauge down (thickness reduction) work, additional shape correction work must be performed, and therefore, there is a problem that not only the efficiency is improved but also the cost is increased.
Furthermore, in the grinding line, the method of grinding the surface of the strip-shaped metal body with a rotary endless belt is the main method, but this method requires a low belt passing speed and a short belt life, requiring frequent belt replacement. I didn't like it. In addition, there is a problem that uniform grinding cannot be performed unless the plate shape before grinding is flat.

Therefore, for the purpose of improving the efficiency of descaling and improving the surface quality of the hot-rolled steel strip, a plurality of pickling treatment steps are provided after the pretreatment step of the tension leveler, and the plurality of pickling treatment steps are performed. Japanese Unexamined Patent Publication (Kokai) No. 59-41482 discloses a descaling line which is combined with a grinding process for mainly removing metal residues and smut. However, although the surface quality of the steel strip is improved to some extent in the descaling line, its effect is limited, and since a large amount of descaling is performed by pickling treatment, a considerably large scale pickling treatment facility is required. Therefore, the initial investment is large, and it is necessary to treat a large amount of waste liquid accompanying the large-scale pickling. Further, since the grinding process provided between each pickling process is not for actively removing the surface flaws of the steel strip, the steel strip passed through the descaling line is used for removing the surface flaws. The problem arises that the plate must be passed to another grinding line.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems, and when removing the surface scale and surface flaws of the strip-shaped metal body, the polishing with ultra-high pressure water is carried out. By applying it improves the surface quality of the strip metal body,
In addition, in the processing process incorporating this, we aim to simplify the pickling process and surface flaw removal process, improve the efficiency of the processing work, and provide a method for processing hot finishing metal strips that does not require blasting in a separate line. The purpose is to

[0006]

In order to achieve the above object, the present invention is to clean the surface layer portion of a metal band having a scale on the surface with ultra-high pressure water to obtain a surface flaw residual ratio of 5% or less. The main feature is a hot-finished metal strip having no surface flaws, and ultra-high-pressure water with a projection pressure of at least 1500 kgf / cm ² is projected onto a metal strip having a scale on the surface at a projection angle of 15 to 65. A method for treating a hot-finished metal strip having no surface flaws, characterized by spraying and sweeping the surface in the range of
And, the abrasive grain material is projected onto a metal band having a scale on the surface together with ultra-high pressure water having a projection pressure of at least 1000 kgf / cm ² , and at this time, the projection angle is set to 5 to 75 ° and the abrasive grain material Depending on the size, # 40 or more to # 40
The gist is a method for treating a hot-finished metal strip having no surface flaws, which is characterized in that the surface is ground and cleaned to 0 or less.

In the method of the present invention, as a pretreatment, an edge trimming or a grinding treatment is performed on the strip-shaped metal body, and then a heating or cooling treatment for modifying the surface scale to cause cracks or peeling is carried out if necessary. May be. Further, depending on the band-shaped metal body, it also includes connecting a leader and continuously threading. Furthermore, it can be incorporated into a series of lines that perform appropriate mechanical conditioning and pickling treatment after treatment using ultra-high pressure water.

[0008]

The strip metal body and the method for treating the strip metal body according to the present invention will be described in detail below. Generally, the thickness of the scale and the depth of surface flaws generated by hot rolling or annealing in the subsequent process or continuous casting of thin slabs are at least 5 to 10 μm.
Since it is about m, it is necessary to grind at least 10 μm in order to remove the scale and surface flaws, and it is preferable to exceed 20 μm for more reliable grinding.

As described above, conventionally, mechanical descaling by a rotary belt grinder and pickling treatment have been mainly used for surface grinding of a strip-shaped metal body, but there are problems in service life and equipment. People are
As a result of repeated various tests, focusing on ultra-high pressure water polishing that can efficiently achieve the above grinding depth by efficiently removing cracks and flaws, the residual rate of surface flaws on the strip-shaped metal body was reduced to 5% or less. Then, it was found that the surface quality of the product after cold rolling and annealing was extremely good, and as shown in FIG. In particular, it has been found that the linear scale flaws can be more efficiently removed by keeping the ultra-high pressure water polishing under appropriate conditions and using an abrasive grain material together. 2 to 5 show test results under various conditions. Here, the surface flaw residual rate is divided into 1 m units in the longitudinal direction of the coil, and if there is one flaw in the division, the area is the flaw area, flaw length (m) length / coil length (m) × 100. (%) Is defined.

FIG. 2 shows a projection pressure of 3000 to 3500 kgf / cm.
^It shows the relationship between the projection angle and the surface flaw residual rate of the strip-shaped metal body when only the ultra-high-pressure water set to ² is jetted. The projection angle is an angle formed by the jetted ultra-high pressure water intersecting the surface of the strip-shaped metal body. From this figure, it can be seen that the residual rate of surface defects is 5% or less in the projection angle range of 15 to 65 °. Similar to FIG. 2, FIG. 3 shows the relationship between the projection pressure of ultra-high pressure water containing no abrasive particles and the residual rate of surface flaws.
To reduce the surface flaw residual rate to 5% or less, the projection pressure is set to 150.
It can be seen that it is necessary to set it to 0 kgf / cm ² or more.

On the other hand, FIGS. 4 and 5 show the relationship between the projection angle and the projection pressure and the surface flaw residual ratio in the case of using ultra-high pressure water mixed with an abrasive. Abrasive grain material is abrasive grain count # 40 to # 40
Those in the range of 0 were used. If the grain size number of the abrasive grains jetted together with the ultra-high pressure water falls within the range of # 40 to # 400, the load of the leveling process in the post-process increases if it is less than # 40, and if it exceeds # 400, the grinding is performed. This is because the efficiency becomes poor. Although the projection angle is variously changed in Fig. 4, in order to reduce the surface flaw residual rate to 5% or less, the projection angle may be set in the range of 5 to 75 °, and the range is expanded by mixing the abrasive particles. I know what to do. Further, FIG. 4 shows the relationship with the projection pressure, which is the same as that in the case where no abrasive grain material is mixed.
It is necessary to make it more than kgf / cm ² . As described above, in the present invention, the target descaling and the removal of the surface flaw can be achieved by carrying out the polishing and cleaning within the range of the conditions shown in each of the above figures.

The present invention can be further incorporated into a processing line, and an example of its embodiment will be described with reference to the equipment sequence in FIG. In the figure, 1 is a pay-off reel for rewinding and feeding a strip-shaped metal body, 2 is a strip-shaped metal body that is hot-rolled or continuously cast into thin-walled slabs, and 3 is welding of dummy plates (leaders) to the strip-shaped metal body or leaders. Is a welding machine for performing welding, and for example, a submerged arc welding machine, a TIG welding machine, a plasma welding machine, a spot welding machine, or the like is used.
4 is a trimmer that cuts and removes edge flaws and hot cracks that occur in the strip-shaped metal body during hot rolling or continuous casting of thin-walled slabs, and 5 is a grinder that removes relatively small of these flaws and cracks. It is an edge grinder for doing. After such pretreatment means, the strip-shaped metal body 2 is first subjected to scouring for removing scales and flaws on the surface side by an ultrahigh-pressure water jet device 6 capable of supplying abrasive grains, and then inverted strip-shaped metal body. The back surface side of No. 2 is passed through the ultra-high pressure water jetting device 7 capable of supplying the abrasive grain material which is treated in the same manner as the front side. These ultra-high pressure water injection devices 6 and 7 are provided with nozzles 6a and 7a for injecting abrasive grains together with the ultra-high pressure water. In such polishing treatment with ultra-high pressure water, uniform descaling and flaw removal are possible regardless of the shape and crown of the plate. A device 8 for conditioning the treated surface may be provided subsequent to the ultra-high pressure water jetting device 6. The conditioning device 8 smoothes the front and back surfaces of the metal strip 2. In the illustrated example, the elastic roll 8a paired with the press roll 8b is used, but ultra high pressure water may be used, and the means therefor is not limited. If necessary, a light pickling treatment 11 is subsequently performed to remove the biting abrasive grain material and deburr it. In this case, it is advisable to perform a treatment such that the amount of surface ablation is 0.1 μm or more. In the figure, 9 and 12 are cleaning devices, 10 is a bridle roll, and 13 is a tension reel for winding a strip-shaped metal body.

As described above, when the present invention is incorporated into a treatment line, the equipment is made compact together with the pickling treatment, initial investment is reduced, and low-cost descaling / scratching treatment can be performed. .. Examples of the present invention will be described below.

[0014]

[Examples] Under the conditions shown in Table 1, various strip-shaped metal bodies were subjected to heavy polishing treatment by injecting ultra-high pressure water and ultra-high pressure water containing abrasive grains, followed by conditioning using ultra-high pressure water or elastic whetstone rolls. Then, the surface quality after the treatment and the quality of the cold rolled and annealed product were investigated and evaluated. Elastic grindstone roll
A roll formed by laminating disks coated with abrasive grains (M), a laminate formed by lapping a lap wheel (F) and a nylon resin containing abrasive grains integrally formed in a roll The thing (U) was used. The results are also shown in Table 1. In this table, the amounts of polishing and grinding were measured before and after the treatment, and the removed thickness was calculated from the specific gravity. The evaluation of descaling and flaw removal was as follows. ◯: No scale remains and no surface flaws. Δ: No scale remains, but surface flaws remain. X: Scale and surface flaws remain. The surface quality of cold-rolled and annealed products depends on the degree of luster.
And ranks A to D were evaluated, and rank B or higher was regarded as acceptable. The conditions for cold rolling annealing were normal conditions.

[0015]

[Table 1]

[0016]

[Table 2] Material numbers 1 to 10 in the above table are examples of the present invention, and 1
1 to 17 are comparative examples. Material numbers 11, 12, 14, 15, 17, whose projection angle of ultra-high pressure water is out of the range of the present invention,
No. 19 has a high linear surface flaw residual rate after scouring, and the surface gloss of the product is deteriorated. In particular, the best No. 17, which has a right angle of projection, may not have been subjected to conditioning, but the surface quality after treatment and the surface gloss of the product are significantly reduced. Material numbers 13 and 16 with small pressure projection
Similarly, the surface gloss of the product is poor. Further, in the material number 18 whose abrasive grain number falls below the lower limit of the range of the present invention, linear surface scratches do not remain, but the surface gloss of the product is deteriorated because the surface after rough polishing is rough. On the other hand, the evaluation results of the strip-shaped metal bodies according to the method of the present invention are all good, no scale residue and surface flaws are observed, and the products after cold rolling annealing also have good surface properties.

[0017]

As is apparent from the above, in the present invention, when removing surface scales and surface flaws, ultrahigh pressure water polishing is carried out under appropriate conditions to improve the surface quality remarkably. By further treating the strip-shaped metal body with continuous conditioning and pickling treatment, the surface quality can be further improved and the treatment process can be simplified and the efficiency can be improved. As a result, industrial effects such as reduction of manufacturing cost and improvement of working environment can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a surface flaw residual rate and a gloss rank.

FIG. 2 is a diagram showing the relationship between the projection angle of ultra-high pressure water that does not use abrasive grains and the residual rate of surface flaws.

FIG. 3 is a diagram showing the relationship between the projection pressure of ultra-high pressure water that does not use abrasive grains and the surface flaw residual rate.

FIG. 4 is a diagram showing the relationship between the projection angle of ultra-high pressure water mixed with abrasive particles and the surface flaw residual rate.

FIG. 5 is a diagram showing the relationship between the projection pressure of ultra-high pressure water mixed with abrasive grains and the surface flaw residual rate.

FIG. 6 is a schematic explanatory view showing one embodiment of an apparatus for carrying out the present invention.

[Explanation of symbols]

 1 Payoff reel 2 Band-shaped metal body 3 Welder 4 Trimmer 5 Edge grinder 6 Ultra-high pressure water jetting device with abrasive grains (front side) 6a Jet nozzle 7 Ultra-high pressure water jetting device with abrasive grains (back side) 7a Jet nozzle 8 Conditioning device 8a Elastic grindstone roll 8b Presser roll 9 Cleaning device 9a Brush roll 9b Pressing roll 9c Spray 10 Bridle roll 11 Light pickling device 12 Cleaning device 12a Brush roll 12b Pressing roll 12c Spray 13 Tension reel

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Utsuki 3434 Shimada, Hikari City, Yamaguchi Prefecture Inside the Nippon Steel Corporation Hikari Works (72) Inventor Masafumi Takai 3434 Shimada, Hikari City, Yamaguchi Prefecture New Japan Inside the Hikari Steel Co., Ltd. (72) Inventor Toshihiko Uchida 3434 Shimada, Hikari City, Yamaguchi Prefecture Shin Nippon Steel Co., Ltd. Inside the Hikari Steel Works (72) Inventor Kazumi Daitoku 1 Hitaba-cho, Tobata-ku, Kitakyushu No. 1 Shin-Nippon Steel Co., Ltd. Yawata Works (72) Inventor Hiroyuki Matsumura 3-1-1 Higashikawasaki-cho, Chuo-ku, Kobe, Hyogo Prefecture Kawasaki Heavy Industries, Ltd. Kobe Factory (72) Inventor Kyoji Tsujita Hyogo 3-1-1 Higashikawasaki-cho, Chuo-ku, Kobe-shi, Japan Inside Kawasaki Heavy Industries, Ltd. Kobe factory (72) Inventor Yoshikazu Ikemoto 3-1-1 Higashi-kawasaki-cho, Chuo-ku, Kobe-shi, Hyogo No. 1 Kawasaki Heavy Industries, Ltd. Kobe Factory (72) Inventor Yuu Arai 2-4-1 Hamamatsucho, Minato-ku, Tokyo Kawasaki Heavy Industries Ltd. Tokyo Head Office

Claims (3)

[Claims] 1. A hot-finished metal strip having no surface flaw, characterized in that the scale of the surface layer portion of the metal body strip is scoured by ultra-high pressure water and the residual rate of surface flaw is 5% or less. 2. A surface of a metal body having a scale is sprayed with ultra-high pressure water having a projection pressure of at least 1500 kgf / cm ² at a projection angle of 15 to 65 ° to clean the surface. A method for treating hot-finished metal strips without surface defects. 3. An abrasive grain material is projected onto a metal band having a scale on the surface together with ultra-high pressure water having a projection pressure of at least 1000 kgf / cm ² , and at this time, the projection angle is set to 5 to 75 ° and the grinding is performed. A method for treating a hot-finished metal strip having no surface flaws, characterized in that the grain size is adjusted to # 40 or more and # 400 or less with the count to clean the surface.