JPH0825199A - Flaw removing method for metal band - Google Patents

Abstract

PURPOSE:To decrease a time required for grinding as short as possible so as to attain improving efficiency of removing a flaw by using a work roll of specific diameter to cold roll a metal band by a desired draft thereafter surface ground. CONSTITUTION:In a step b1, a metal band is annealed to be pickled, and in a step b2, fixed cold rolling is performed. In the cold rolling in the step b2, a work roll of 40mm or more 300mm or less diameter is used, to perform cold rolling in a range of 30% or more 60% or less draft. Next in a step b3, a surface of the metal band is ground. Next in a step b4, a Sendzimil mill is used to perform cold rolling to a necessary plate thickness as a target. Then in a step b5, finish annealing pickling is performed. Further in a cold rolling process in the step b2, since a work roll of middiameter is used, a depth of a flaw in a surface, provided in a raw material, is prevented from increasing. Consequently, in the step b3, a flaw can be removed by light grinding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of removing a metal strip containing stainless steel or the like for satisfying the surface quality required as a product.

[0002]

2. Description of the Related Art Stainless steel strips are often used in a form in which the surface of the raw material is close to that of the stainless steel strips by taking advantage of its non-corrosive property. Therefore, the surface quality required as a product of the stainless steel strip is particularly required to be uniform without generation of flaws, deposits, dirt, and the like.

Generally, a metal strip such as a stainless steel strip is cast after smelting, hot-rolled and then cold-rolled, and finished to a required shape and size and JIS or a designated "surface finish". Manufactured to a product having a surface. Surface grinding is performed during this manufacturing process in order to obtain the required surface quality. Defects to be ground often occur in the process up to hot rolling. In the cold rolling, the thickness of the metal strip is greatly reduced, and the metal strip is work-hardened accordingly, and its length is increased. For this reason,
In general, the surface of a metal strip is often ground at a stage where the metal strip is not work hardened, that is, before full-scale cold rolling in which the length of the metal strip does not increase so much.

FIG. 11 shows a manufacturing process example of a stainless steel strip which is one of conventional metal strips. In step a1, the hot-rolled stainless steel strip is subjected to annealing pickling as heat treatment and descaling treatment, and in step a2, its surface is ground to remove flaws. After that, step a3
Then, cold rolling is carried out by a Sendzimir type cold rolling mill equipped with a work roll having a small diameter, and in step a4, a heat treatment for finishing and an annealing pickling as a descaling treatment are carried out. Step a3
Since cold rolling is performed using a work roll having a small diameter, a beautiful surface quality can be obtained. The descaling treatment includes not only pickling, but also electrolysis in a neutral salt bath, mechanical shot blasting, scale breaker, and the like.

As shown in FIG. 12, the grinding of step a2 is performed before the cold rolling of step a3. As shown in FIG. 12, the surface of the metal strip 1 to be rolled is subject to shavings, scratches, scratches and the like. If it remains, it will fall off during cold rolling, it will adhere to the roll, and it will be caught between the work roll and the support roll to create a recess in the work roll, and this recess will be on the surface of the metal strip. This is because the transfer marks are easily transferred and roll marks are likely to occur. The surface defects such as the hair 2 are generated by partially remaining undissolved when the oxide film formed on the surface in the annealing process is chemically descaled in the pickling process. In the step of surface grinding of step a2 in FIG.
Is provided for the purpose of efficiently removing without lowering the yield as much as possible while the length thereof, that is, the surface area is not increased by rolling.

However, the metal band before cold working is considerably soft, especially in ferritic stainless steel, and the surface of the grinding belt (endless rotary belt having abrasive grains) is likely to be clogged. Therefore, for example, Japanese Patent Publication No. 62-60164 and Japanese Examined Patent Publication No. 2-2928 disclose a technique of polishing the surface of a metal strip after the completion of cold rolling.

[0007]

If the surface of the metal strip is scratched before cold rolling, the surface of the polishing belt is clogged as described above, and it is difficult to remove the scratch. If it is done after cold rolling, it is hardened because it is work hardened, and the polishing of the surface of the metal strip will be finer than if it was done before cold rolling.
As the plate thickness becomes thinner and its length extends, and because it is work hardened, it becomes difficult to polish and takes a long time to remove the flaw. In addition, cold rolling must be performed by breaking the metal strip to a larger size with a work roll having a small diameter.However, when this is done, the surface flaws are crushed and the surface of the metal strip is folded or overlapped with the surface of the base metal. It is easy to be embedded in the steel and its depth is not necessarily reduced by rolling. Therefore, the plate thickness becomes thin, and it is necessary to grind relatively deeply to the surface that is long, that is, wide, and therefore the loss due to the metal band surface grinding increases and the flaw removal yield decreases greatly, This unnecessarily lengthens the grinding time and deteriorates the efficiency and productivity.

Further, as described above, products such as stainless steel are often used in a form in which the surface of the material is close to the original state, and the surface quality required for this is J
As IS and designated "surface finish", there are various polished finish products as well as non-polished finish products. To ensure the required surface quality without surface flaws, deposits and dirt, and to produce such polished or non-abrasive finished products, in the process of removing surface flaws such as stainless steel strip during the manufacturing process. Must be made so that the polishing marks imparted to the surface of the stainless steel strip or the like by the surface flaws are not left on the polished or non-polished finished product and the surface quality is not deteriorated. In addition, while finishing various kinds of processing including cold rolling to finish polished or non-polished products, it is necessary to keep natural load as much as possible so that such polishing marks do not significantly obstruct and apply a great load. It must disappear and both products must be finished in excellent finishes.

The object of the present invention is to produce various metal band surface finish products which are prescribed or specified with high quality and efficiency, and in order to obtain the necessary surface quality, the loss of metal band due to surface grinding is minimized. It is possible to reduce the scratch removal yield and reduce the scratch removal yield, and to shorten the grinding time as much as possible to improve the scratch removal efficiency and its productivity and to perform very efficient surface grinding. It is to provide a taking method.

[0010]

According to the present invention, a metal strip is cold-rolled at a rolling reduction of 30% or more and 60% or less using a work roll having a diameter of 40 mm or more and 300 mm or less. It is a method of removing a flaw in a metal band, which is characterized by performing surface grinding later.

The diameter of the work roll of the present invention is
It is characterized in that it is in the range of 220 mm or more and 300 mm or less.

The metal strip of the present invention is characterized in that it is a hot rolled metal strip.

The metal strip of the present invention is characterized in that it is a hot-rolled steel strip of stainless steel.

[0014]

According to the present invention, a work roll having a diameter of a metal band of 40 mm or more and 300 mm or less is cold-rolled in a rolling reduction of 30% or more and 60% or less and then surface grinding. The flaw removal method of the metal strip for ensuring the required surface quality according to the present invention is in the middle of the cold rolling step during the production step of the metal strip, that is, in the middle of the cold rolling,
The method is carried out after first cold rolling within the above condition range. By such a cold rolling, even if the metal strip has a defective shape or plate thickness, these can be corrected, so that it is possible to easily and reliably perform uniform surface grinding. The surface of the metal strip is appropriately work-hardened so that clogging at the time of surface grinding is less likely to occur, and efficient surface grinding can be performed in terms of flaw removal yield, efficiency, and productivity. Further, since the work roll having a diameter of 300 mm or less is used, the metal strip can be easily cold-rolled at a rolling reduction of 30% or more. Furthermore, since the surface of the metal strip is ground after the metal strip is appropriately work-hardened by cold rolling within the above-mentioned condition range, the polishing marks generated on the surface of the metal strip are compared with those of the unrolled one. However, since it is fine and cold-rolled again after the surface is ground, this abrasive grain disappears during the manufacturing process promotion without any load, and it may remain in the polished or non-polished finished product. Disappear. Therefore, both products can be finished into excellent finished products.

Further, according to the present invention, since the diameter of the work roll is in the range of 220 mm or more and 300 mm or less, it is possible to surely make the surface of the metal strip shallow without deepening the flaw.

According to the invention, since the metal strip is a hot-rolled metal strip, a flaw or the like formed on the surface during hot rolling is first cold-rolled to appropriately harden the surface. It can be easily removed in a closed state with a shallow depth.

Further, according to the present invention, since the metal strip is a hot-rolled steel strip of stainless steel, surface flaws and the like generated in the process of hot rolling are first processed by cold rolling. It can be easily removed by surface grinding in a hardened state and in a state where the flaw is shallow. Since the flaw is shallow, the amount of metal strip that is lost during surface grinding is small, and the flaw removal yield is improved. Further, the surface quality required for the stainless steel strip can be efficiently achieved.

[0018]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows a manufacturing process of a stainless steel strip according to an embodiment of the present invention, and FIG. 2 shows a structure of a processing line suitably used for an annealing pickling process and a cold rolling process of this embodiment, and FIG. Shows the change of the surface condition in the cold rolling process of the embodiment of FIG. 1, FIGS. 4 and 5 show the reason why the surface condition is different depending on the diameter of the work roll, and FIG. 6 shows the production according to another embodiment of the present invention. The process is shown in FIGS.
0 indicates the curing and the like according to the embodiment of FIG.

As shown in FIG. 1, according to the present embodiment, the hot rolled steel strip of stainless steel is annealed and pickled in step b1, and a certain cold rolling is performed in step b2.
The cold rolling in step b2 is 3 mm when the diameter is 220 mm or more.
Using a medium diameter work roll of 00 mm or less, the reduction rate is 30
Cold rolling in the range of 60% to 60%. Next, in step b3, the surface of the stainless steel strip is ground. Next, in step b4, a Sendzimir type rolling mill is used to perform cold rolling to a desired required plate thickness. Next, in step b5, finish annealing pickling is performed.

When the final cold rolling rate is large or when the metal strip cannot be cold rolled to the desired required plate thickness due to work hardening, after the grinding in step b3, the intermediate annealing is performed again in step b6. Pickle, step b
In step 7, cold rolling is performed using a Sendzimir type rolling mill, and in step b8, finish annealing and pickling is performed.

In the cold rolling process of step b2, since the medium diameter work roll is used, the depth of the flaw on the surface of the material does not become deep. Therefore, in step b3, the flaw can be removed by light grinding.

FIG. 2 shows a basic structure of a continuous annealing pickling cold rolling line which is preferably used for carrying out the processes of steps b1 and b2 of FIG. The application of such a series of equipment is disclosed in, for example, Japanese Patent Laid-Open Nos. 5-212410 and 5-228504. The tandem cold rolling facility 10 is provided with a plurality of multiple rolling mills 11. A plurality of coils are sequentially supplied from the payoff reel 13 to the metal strip 12 to be passed, the tail end of the leading strip and the tip of the trailing strip are welded by the welding machine 14, and the annealing furnace is passed through the entrance looper device 15. 16 introduced. The annealed metal strip is introduced into the tandem cold rolling facility 10 from the descaling device 17 including a pickling tank and the like through the exit side looper device 18. The cold-rolled metal strip is cut at a welded portion by a shearing machine 19 and wound into a coil by a tension reel 20.

FIG. 3 shows the relationship between the rolling ratio and the surface roughness with the diameter of the work roll of the rolling mill as a parameter. Although the surface roughness becomes smaller as the diameter of the work roll becomes smaller, a state in which the flaw is covered or a state in which the flaw is pushed in tends to occur. Considering the degree of covering and indentation of flaws, the diameter of the work roll of the rolling mill is 250 from FIG.
It can be seen that the range of mm to 300 mm is preferable. Figure 2
In the tandem type cold rolling equipment 10 as shown in FIG. 2, the rolling mill 11 used is preferably a multiple rolling mill using a work roll having a diameter of 220 mm or more and 300 mm or less.

FIG. 4 shows the reason why a work roll having a large diameter as shown in FIG. 4A is less likely to be covered with a flaw than a work roll having a small diameter as shown in FIG. As shown in (A), in the work roll having a large diameter, the flaw is spread and becomes shallow. On the other hand, (B)
In the work roll having a small diameter as shown in (1), the flaw portion is folded without being widened, and although it looks shallow, it is likely that the overlapping behavior of the flaws causes a covering behavior.

FIG. 5 shows a shape change based on an experimental result of rolling an indentation when measuring Vickers hardness with a large-diameter roll and a small-diameter roll. Similar to Fig. 4, in the large-diameter roll, the reduction, which is the rolling reduction, is increased, and the indentation becomes shallower and longer, whereas in the small-diameter roll, the indentation is extruded from the inner side and the deep portion becomes narrower but shallower. Don't In this way, with the large diameter roll and the small diameter roll,
It has been confirmed that the deformation mode of the indentation is different.

FIG. 6 shows a manufacturing process according to another embodiment of the present invention. In step c1, annealing pickling is performed, in step c2 first pass cold rolling, in step c3 surface finish polishing, in step c4 second pass cold rolling, and in step c5 annealing acid is performed. Do a wash. Bright annealing may be performed instead of annealing pickling. Table 1 below shows the specifications of the test material used in the experiment for confirming the effect of the manufacturing process of FIG. No. No. 1 is austenitic SUS304, and No. 1 2 is ferritic SUS
430. Moreover, "Red" shows a reduction rate.

[0027]

[Table 1]

The step of finish polishing in step c3 is SUS.
For 304, the conditions are shown in Table 2 below, and for SUS430, the conditions are shown in Table 3 below.

[0029]

[Table 2]

[0030]

[Table 3]

For comparison, an example of dividing symbol P is shown in which the finish polishing is directly performed without performing the cold rolling in step c2 and then the rolling is performed in two passes. That is, FIG.
This is a conventional method of performing cold rolling in two passes in step a3 of the manufacturing process. The embodiment shown in FIG. 6 is shown as the split symbol Q. The results of this comparison are shown in Table 4 below.

[0032]

[Table 4]

According to the results of this experiment, the ratio of polishing loss at the time of finish polishing is slightly numerically larger than that of this embodiment, but it is recognized to be within the error range. Among the mechanical properties, Hv represents Vickers hardness, Ts represents tensile strength, and El represents elongation.

7 to 10 show the results of the grinding test. 7 and 8 show SUS304 and SUS430.
9 and 10 show the transition of the accumulated grinding amount of FIG.
Shows the transition of the surface roughness of SUS304 and SUS430, respectively. In the case of this embodiment, since the surface is polished after rolling, it is necessary to polish a long surface in a thin state. Even if this length is corrected, the cumulative amount of grinding in this example is slightly larger than that of the comparative example, and the surface roughness is also improved. Furthermore, since it is hardened after polishing,
The clogging of the grinder is less likely to occur.

[0035]

As described above, according to the present invention, since the surface of the metal strip is ground and the flaws are removed in the middle of the cold rolling, the defective shape of the metal strip is corrected and the metal strip is appropriately work hardened. However, clogging is less likely to occur during surface grinding. The polishing marks formed on the surface of the metal strip are finer than those of the unrolled one, and since they are cold-rolled again, the polishing marks disappear and do not remain in the product. Furthermore, since the surface is ground in the state where the surface flaw is shallow, the amount of grinding for achieving a high quality surface finish is reduced, the loss of the metal band and the grinding time are reduced, and the flaw removal yield, the efficiency, Efficient surface grinding can be performed in terms of productivity.

Further, according to the present invention, since the diameter of the work roll is 220 mm or more and 300 mm or less, the depth of the surface flaw can be reduced when the metal strip is pressed to reduce the plate thickness, and the grinding can be performed. The amount can be reduced for efficient surface grinding.

Further, according to the present invention, the surface of the hot metal strip is provided with a flaw or the like which is generated and adheres during the hot rolling process.
In a state where the surface is hardened more appropriately than in the hot-rolled state to prevent clogging, and where the flaws are shallow,
Efficient surface grinding can be achieved while achieving a high quality surface finish.

According to the present invention, the stainless steel hot-rolled steel strip is efficiently ground by cold-rolling the surface of the hot-rolled steel strip to an appropriate degree so as to prevent clogging so that the stainless steel strip The quality required for the surface can be efficiently and easily satisfied.

[Brief description of drawings]

FIG. 1 is a manufacturing process drawing of an embodiment of the present invention.

FIG. 2 is a simplified block diagram showing a configuration of a process line preferably used in the manufacturing process of FIG.

FIG. 3 is a graph showing changes in surface roughness with the diameter of a work roll as a parameter in the example of FIG.

FIG. 4 is a schematic cross-sectional view showing the relationship between the diameter of a work roll and surface flaws.

FIG. 5 is a schematic diagram showing a relationship between a diameter of a work roll and a surface flaw.

FIG. 6 is a manufacturing process drawing of another embodiment of the present invention.

FIG. 7 is a graph showing effects of the example of FIG.

FIG. 8 is a graph showing effects of the embodiment of FIG.

FIG. 9 is a graph showing the effect of the embodiment of FIG.

FIG. 10 is a graph showing the effect of the embodiment of FIG.

FIG. 11 is a conventional manufacturing process diagram.

FIG. 12 is a simplified schematic diagram showing a state in which a roll mark is formed.

[Explanation of symbols]

 10 Tandem cold rolling equipment 11 Rolling mill 12 Metal strip 16 Annealing furnace 17 Descaling equipment

Claims (4)

[Claims] 1. A metal strip having a diameter of 40 mm or more is 300 mm.
Using a work roll in the range of mm or less, a reduction rate of 30
%, The surface of the metal strip is ground after cold rolling in the range of 60% or more and 60% or less. 2. The diameter of the work roll is 220 mm
The flaw removal method for a metal band according to claim 1, wherein the flaw resistance is within the range of 300 mm or less. 3. The flaw removal method for a metal strip according to claim 1, wherein the metal strip is a hot rolled metal strip. 4. The flaw removal method for a metal strip according to claim 1, wherein the metal strip is a hot rolled stainless steel strip.