JPH06292904A - Cold rolling method and surface grinding line for hot rolled steel strip - Google Patents

Abstract

(57) [Abstract] [Purpose] Surface defects are likely to occur due to seizure during hot rolling. If the surface defects that occur are ground using a belt grinder, some of the surface defects will remain as recesses. Provide cold rolling method for hot rolled stainless steel strip. [Composition] Non-lubricating cold rolling without rolling oil is performed in one or more passes on the hot-rolled steel strip 11 that has remained after the maintenance, where some of the surface flaws are concave flaws 14 and remain. Then, normal cold rolling of one pass or multiple passes is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold rolling method for hot rolled steel strips, and a surface grinding line for hot rolled steel strips used as a rolling material for this cold rolling. More specifically, the present invention is particularly apt to cause surface defects due to seizure or flaws during hot rolling, and uses a full-width surface grinding device composed of, for example, a belt grinder for maintenance of the generated surface defects. When performing, cold rolling method of hot rolled stainless steel strip that remains as a residual flaw where a part of the surface flaw is a recess, and surface grinding of hot rolled stainless steel strip that is used as a rolling material for this cold rolling. Regarding the line.

[0002]

2. Description of the Related Art As is well known, a hot-rolled steel strip is produced by, for example, heating a slab produced by continuous casting or slabbing using a heating furnace, or receiving it as a hot piece, and using a rough rolling machine and finish rolling. Hot rolled by machine to 1.0-25.4mm
A hot-rolled steel strip having a thickness is wound around a coil by a coiler and cooled, and then various refinement steps are performed to obtain a finished product. In the production of the cold-rolled steel strip, the hot-rolled steel strip is thereafter used as a rolling material for cold rolling.

In the hot rolling process, surface defects are generated as surface defects of the hot rolled steel strip. The surface defects are caused by the hot rolled steel strip or a cold rolled steel strip using the hot rolled steel strip as a rolling material. The appearance of the final product to be used is spoiled, and in particular in the manufacturing process of the cold-rolled steel strip, it may cause breakage or cracking, so that the occurrence thereof is suppressed. In particular, a hot rolled stainless steel strip used as a rolling material for a cold rolled stainless steel product having an extremely high target aesthetic quality is naturally required to have an extremely high surface quality.

The types of surface flaws of hot-rolled steel strips are described in "Handbook of Steel, Third Edition, III (1) Rolling Foundation / Steel Sheets" (page 401, see Tables 7 and 28), and surface flaws of hot-rolled stainless steel strips. The types of "steel handbook, 3rd edition III (1) rolling foundation and steel plate" (p. 449, table 7)
・ See 57).
There are many flaws such as roll flaws, abrasion flaws, and winding flaws, but the causes of these flaws are not uniform. Therefore, it is extremely difficult to completely eliminate the occurrence of these surface defects as long as the hot rolled steel strip is manufactured using the current production equipment. In particular, stainless steel is apt to cause seizure during hot rolling, and the range and extent of occurrence of surface defects are remarkable.

By the way, such a surface flaw is also called an eclipse flaw, and it is produced by covering the surface of a hot-rolled steel strip as if it were covered with a thin skin, and is treated at the stage of hot-rolled steel strip. When cold rolling is performed without sufficiently performing (in the present specification, removal or suppression of surface flaws by grinding using a grinder, for example), surface flaws are gradually extended in the longitudinal direction by rolling. Although the degree of surface flaws is gradually improved by this cold rolling, the distinguishability of surface flaws is only reduced due to the shallow depth. 1st pass: Reduction rate of about 10%,
The second half: a reduction rate of about 5%, the final: a reduction rate of about 1 to 2%) does not completely eliminate the surface flaws, and even after cold rolling, the surface of the cold-rolled steel strip has recesses or fogging. It is empirically known to exist as. On the other hand, if the surface flaws are sufficiently removed or reduced by grinding at the stage of hot-rolled steel strip, the depth of the recesses will gradually become shallower even after cold rolling at a normal reduction ratio, and finally the cold-rolled steel will be cooled. It is empirically known that the steel strip does not have a recess.

Therefore, in the production of hot-rolled steel strip, especially hot-rolled stainless steel strip, after winding, 100% inspection of the outer surface of the coil is carried out on the coil conveyor, or the coil is taken off line. Coil winding,
Alternatively, the inner winding was pulled out, and the presence or absence of a surface flaw was inspected by either performing a surface inspection or a rear surface inspection, and the coil in which the occurrence of the surface flaw was recognized was subjected to maintenance (grinding).

As a grinding means, if only a portion where surface defects are generated is partially ground at the stage of hot-rolled steel strip, and then the hot-rolled steel strip is cold-rolled, the cold-rolled steel strip can be efficiently produced. It seems that it is possible to prevent the formation of recesses on the surface.

However, if only the surface-defect-generated portion is partially ground, a difference in mass between the ground portion and the non-ground portion occurs, and a reduction in elongation occurs due to the reduction of the cold rolling performed thereafter. The rolled steel strip may be perforated, fractured, or narrowed. Therefore, it is not possible to partially grind only the part where surface defects occur, and the conventional grinding method for surface defects of hot-rolled steel strip is to keep the elongation rate of the entire strip during cold rolling constant. In addition, the entire width of the hot-rolled steel strip was ground to a uniform depth.

FIG. 8 (a) shows an example of a full-width surface grinding device 85 conventionally used for grinding a hot-rolled steel strip, and four hot-rolled steel plates having four full-width surface grinding devices 85a to 85d are arranged. Obi 81
The surface grinding lines 80 are shown in FIG. 8 (b). The reference numerals in the figure with lowercase letters in FIG. 8 (b) have the same meaning as the reference numerals in FIG. 8 (a).

As shown in FIG. 8 (a), a full width surface grinding device
Reference numeral 85 denotes a reciprocating movement through two drive rolls 82 and 83 which are arranged in parallel so that the cylinder length direction is orthogonal to the conveyance direction of the hot-rolled steel strip 81 (the direction of the white arrow in the figure). 8 (b) is a belt grinder composed of grinding belts 84 arranged so as to have a width larger than the width of the steel strip.
As shown in FIG. 4, normally four units are installed in series between the payoff reel 87 and the tension reel 88.

In FIG. 8 (b), the coil to be cared for is once delivered to the hot-rolled steel strip 81 by using the pay-off reel 87 and the tension reel 88, and the upper surface of the hot-rolled steel strip 81 is shown in FIG. 8 (a).
4 full-width surface grinding machines 85a to 85d, each of which has been described in the above, are installed in series. On the opposite side of the hot-rolled steel strip 81, four full-width surface grinding machines 85a to 85d are installed.
d Corresponding crimp rolls 86a to 86 for each
Grinding belts 84a to 84d for moving the hot-rolled steel strip 81 by arranging d and raising the pressure rolls 86a to 86d.
The strip 81 was ground to the entire length and width of the strip 81, respectively.

However, since the grinding amount by the full-width surface grinding device is usually about 15 to 40 μm / pass, surface flaws having a depth larger than this are not eliminated even by such grinding means, and the hot rolled steel It was left as a residual flaw that was a recess in the belt. Therefore, when cold rolling is performed using such a hot-rolled steel strip as a rolling material, a recess is generated on the surface of the obtained cold-rolled steel strip, which is a serious quality problem.

Further, in such conventional grinding, since the full width of the hot rolled steel strip is ground using the full width surface grinding device,
Except for the part where the surface flaw is generated, it is necessary to grind at the same depth as the part where the surface defect is generated. Both the grinding amount of the hot rolled steel strip and the abrasion amount of the grinding belt are large, and it takes a long time to grind. Therefore, the yield and the productivity were remarkably reduced.

Japanese Unexamined Patent Publication (Kokai) No. 62-63059 discloses a grinding robot equipped with a hand detector having a flaw detector, a grinder and a grindstone contact degree detector at its tip, and an image processing apparatus for detecting the flaw position. Of the surface flaw of the steel piece provided with an arithmetic processing unit that processes signals from the image processing unit, the flaw detector, and the contact degree detector, and a drive control unit that operates the grinding robot according to the signal from the arithmetic processing unit An automatic grinding machine has been proposed. This automatic grinding machine is capable of
It is a device that combines detection, grinding, holding, and moving mechanisms so that the grinding mechanism can accurately follow such changes even when the situation such as abrasion of the grindstone occurs.

On the other hand, in Japanese Patent Laid-Open No. 3-86318, a steel strip payoff reel and a paper winder, a steel strip tension reel and a paper payoff reel are provided.
Following the payoff reel, there has been proposed a continuous flaw removal grinding device for stainless steel strips in which a steel strip welding machine, a steel strip elastic grindstone grinding device, and a steel strip belt grinding device are sequentially arranged.
This continuous flaw removal grinding machine performs heavy grinding with an elastic grindstone,
Subsequent belt grinding eliminates the polishing marks and at the same time makes the polishing uneven.

[0016]

However, Japanese Patent Laid-Open No. 62-63.
The automatic grinding machine proposed by Japanese Patent No. 059 has been proposed in consideration of removal of surface flaws of a steel slab, and it is necessary to surely remove surface flaws of a hot-rolled steel strip which is a rolling material of a cold-rolled steel strip. I can't. The precision of the depth of surface flaws to be removed is significantly different between the steel strip and the hot-rolled steel strip, which is the rolled material of the cold-rolled steel strip (steel strip: 1 to 5 mm, hot-rolled steel strip: 0.015 to 0.100 mm degree)
Because.

Further, since the grinding equipment proposed by Japanese Patent Laid-Open No. 3-86318 is a grinding equipment on the premise that the entire width of the steel strip is uniformly grounded, this method is similar to the conventional method. In addition, it is impossible to solve the problem that residual flaws are generated and the yield and the productivity are significantly reduced.

Here, an object of the present invention is to provide a cold rolling method for a steel strip, and a surface grinding line for a hot rolled steel strip used as a rolling material for this cold rolling, specifically, In particular, surface flaws are likely to occur due to seizure during hot rolling, and if the generated surface flaws are ground using, for example, a full-width surface grinding device consisting of a belt grinder, some of the surface flaws remain as recesses. Cold rolling method for hot rolled stainless steel strip,
Another object of the present invention is to provide a surface grinding line for a hot rolled stainless steel strip used as a rolling material for this cold rolling.

[0019]

As a result of various studies to solve the above-mentioned problems, the present inventor first found that a hot-rolled steel strip having residual flaws was first lubricated without using rolling oil. It has been found that the recesses on the surface of the cold rolled steel strip can be eliminated by performing cold rolling and then lubricating cold rolling under normal rolling conditions using rolling oil.

FIG. 1 schematically shows a situation in which cold rolling is performed by a cold rolling roll 12 on a hot-rolled steel strip 11 having residual flaws 13 and 14 even after grinding by a full-width surface grinding device composed of a belt grinder. FIG. 1 (a) shows a situation in which lubrication cold rolling is performed, and FIG. 1 (b) shows a situation in which non-lubrication cold rolling is performed.

As shown in FIG. 1 (a), in the lubrication cold rolling, the rolling oil 15 is accumulated in the concave portion 13 which is a residual flaw, and the accumulated rolling oil 15 is contained in the concave portion 13. Therefore, even if a reduction is applied by the cold rolling roll 12, the volume of the concave portion 13 hardly changes, and the extension of this portion is insufficient. That is, the recess 13
However, since the cold rolling roll 12 and the hot-rolled steel strip 11 contact each other through a thick oil film and do not directly contact each other, a difference in elongation rate occurs between the recess 13 and other general parts. As a result, the hot-rolled steel strip 11 may be broken or punctured during cold rolling, and the formation of recesses on the surface of the cold-rolled steel strip after cold rolling cannot be eliminated.

On the other hand, as shown in FIG. 1 (b), in the unlubricated cold rolling, since the rolling oil 15 is not used, the oil film is not accumulated in the recesses 14, so that the cold rolling by the cold rolling roll 12 is performed. At this time, there is no difference in elongation rate with respect to other general parts. Therefore, even if lubrication cold rolling is performed thereafter, breakage or perforation of the steel strip 11 does not occur, and since the reduction can be sufficiently performed, the concave portion on the surface of the steel strip 11 can be eliminated. . In unlubricated cold rolling, the reduction amount is 0.5 m.
If it is set to m or less (or the rolling reduction is 0.5 to 10% or less), the rolling force will not be excessively increased and seizure will not occur.
There is no problem in operation.

As a result of further studies based on such findings, the present inventor found that not only the rolling conditions for cold rolling but also grinding was used to eliminate the recesses on the surface of the cold rolled steel strip. The size (length, depth, and width) of the residual flaws on the surface of the hot-rolled steel strip after that also has an effect, that is, unlubricated cold rolling and lubricated cold rolling are performed at appropriate timing according to the dimensions of the residual flaws. By switching and using together,
The present invention has been completed by finding that it is possible to manufacture a cold-rolled steel strip having no recesses due to residual flaws in the hot-rolled steel strip without causing breakage or perforation during cold rolling.

Here, the gist of the present invention is a cold rolling method of a hot-rolled steel strip which remains after a surface flaw is ground and a part of the surface flaw becomes a residual flaw which is a recess. The hot-rolled steel strip is subjected to one-pass or multiple-pass unlubricated cold rolling and then subjected to one-pass or multiple-pass lubricated cold rolling to eliminate the recess. It is a cold rolling method.

More specifically, the present invention relates to a cold rolling method for hot-rolled steel strip, which is a residual flaw that is a concave portion after the surface flaw has been ground. FIG. 2 is a cross-sectional view and a plan view of an example of such a hot-rolled steel strip.
In (a) and FIG. 2 (b), (i) the depth b of the recess 21 is 0.
If it exceeds 5 mm, the hot-rolled steel strip 20 is subjected to one-pass or multi-pass unlubricated cold rolling to reduce the depth b of the recess 21 to 0.5 mm or less, and the length a of the recess 21. Between the depth b and the width c, the hot-rolled steel strip 20 should be filled with one pass or a plurality of passes after satisfying the relationship shown in Table 1 or a graph shown in FIG. Lubrication cold rolling is performed, and (ii) when the depth b of the recess 21 is 0.5 mm or less, it is determined whether the length a, the depth b and the width c of the recess 21 satisfy the above relationship. However, when satisfied, the hot-rolled steel strip 20 is subjected to one-pass or multiple-pass unlubricated cold rolling without performing one-pass or multiple-pass lubricated cold rolling, and when not satisfied, the hot-rolled steel strip 20. 20 1-pass or multi-pass unlubricated cold rolling to satisfy the above relationship, and then 1 pass or multi-pass lubrication cooling By performing rolling, a cold rolling method of hot rolled strip, characterized in that to eliminate the recess 21.

As described above, according to the present invention, since the steel strip during cold rolling does not cause cutting or perforation, only the portion where the surface flaw is generated is partially formed during grinding of the hot rolled steel strip. It becomes possible to grind to. Therefore, the present inventor has conducted further studies and has conceived a surface grinding line for partially grinding the hot-rolled steel strip having surface defects.

Here, another gist of the present invention is, as shown in FIG. 3, which is an explanatory view of an example of a surface grinding line according to the present invention, a payoff reel 37 for paying out a coil, a payoff reel 37. Hot-rolled steel strip delivered by
It is arranged between the tension reel 38 that winds 31 around the coil, and the payoff reel 37 and the tension reel 38,
A surface grinding line 30 for a hot-rolled steel strip 31 equipped with a combination of full-width surface grinding devices 35a to 35d for grinding the entire width of the hot-rolled steel strip 31, further comprising a full-width surface grinding device 35a to 35d.
A surface grinding line 30 for a hot-rolled steel strip 31 is characterized in that a spot grinding device 39 for the hot-rolled steel strip 31 is arranged between the hot-rolled steel strip 31 and a tension reel 38.

More specifically, the present invention is a pay-off reel for paying out a coil as shown in FIG. 4, which is an explanatory diagram in which a spot grinding device 39 in the surface grinding line 30 according to the present invention shown in FIG. 3 is extracted. (Not shown), a tension reel (not shown) that winds the hot-rolled steel strip 41 paid out by the pay-off reel around a coil, and a full width of the hot-rolled steel strip 41, which is arranged between the pay-off reel and the tension reel. A surface grinding line 40 of a hot-rolled steel strip 41 provided with a combination of a full-width surface grinding device (not shown) that grinds, further comprising (i) a payoff reel and a full-width surface grinding device, A primary optical flaw detection device 42 including image processing devices 42a to 42f, and (ii) an arithmetic processing device for processing a signal sent from the primary optical flaw detection device 42
43, and (iii) a primary spot grinding device provided with a drive control device 44a arranged between the full-width surface grinding device and the tension reel, which is operated by a signal from the arithmetic processing device 43.
44, (iv) a secondary optical flaw detection device 45, which is provided between the primary spot grinding device 44 and the tension reel and includes image processing devices 45a to 45e, and (v) a secondary An arithmetic processing device 46 for processing a signal sent from the optical flaw detection device 45, (vi) disposed between the secondary optical flaw detection device 45 and the tension reel, from the arithmetic processing device 46. A surface grinding line 40 for a hot-rolled steel strip 41, characterized in that it has a secondary spot grinding device 47 equipped with a drive control device 47a that operates in response to a signal in combination.

In the surface grinding line 40 according to the present invention described above, it is desirable that the secondary spot grinding device 47 be provided with at least two or more kinds of grinding members for rough grinding and finish grinding so as to be switchable. According to the surface grinding line of the present invention, it is possible to locally grind only the portion where the surface flaw is generated and the vicinity thereof, so that the yield reduction of the coil grinding is suppressed and the grinding efficiency is improved. You can

"Surface flaw" in the present invention is a kind of surface defect of a hot rolled steel strip and is used in the hot rolling process to grind.
(Maintenance) It refers to minute dents formed on the surface of the hot rolled steel strip before. The "residual flaw" in the present invention is a kind of surface defect of the hot rolled steel strip, and means a minute recess remaining on the surface of the hot rolled steel strip after maintenance.

In the present invention, "lubricating cold rolling" means ordinary cold rolling performed using rolling oil, and "unlubricated cold rolling" means cold rolling performed without using rolling oil. To do. In the case of unlubricated cold rolling, roll wear, increase of rolling load, deterioration of appearance quality of rolled material, deformation due to heat generation, etc. may occur, but the reduction amount should be 0.5 mm or less (or reduction ratio should be 0.5-10). % Or less), there is no problem in operation.

As described above, the point of the present invention is to perform unlubricated cold rolling without using rolling oil and lubricated cold rolling with rolling oil when performing cold rolling on a hot-rolled steel strip having residual flaws. By carrying out in this order, even if only the surface flaw occurrence portion is partially ground on the hot rolled steel strip which is a rolling material,
The point is that the cold-rolled steel strip can be manufactured stably by eliminating the recesses on the surface of the cold-rolled steel strip while preventing the steel strip from being cut and perforated during cold rolling.

In the present invention, a difference in gloss between cold-rolled portions may occur between the ground portion and the non-ground portion due to the difference in the amount of rolling oil enclosed during cold rolling. However, depending on the application of the cold-rolled steel strip (for example, exhaust gas material such as a muffler for automobiles), such a difference in gloss is not a problem, and the existence of residual flaws is often a problem. The cold-rolled steel strip finally provided by the cold-rolling method according to the present invention using the hot-rolled steel strip ground by the surface grinding line according to the present invention as a rolling material is suitable for such use.

[0034]

The operation of the present invention will be described in detail below. In the present invention, when a cold rolled steel strip is manufactured by performing cold rolling on a hot rolled steel strip that has undergone maintenance (grinding) for the entire width of the surface that has passed through the surface grinding line, cold rolling is performed as in the conventional case. As rolling, not only normal lubrication cold rolling using rolling oil is performed, but unlubricated cold rolling without rolling oil is first performed in one pass or multiple passes, and then one pass or multiple passes lubrication cooling is performed. Hot rolling.

The hot-rolled steel strip having a residual flaw as a concave portion is first subjected to one-pass or multiple-pass unlubricated cold rolling, so that the concave portion and other concave portions are formed as described with reference to FIG. The reduction can be performed without causing a difference in elongation rate due to the reduction with the general portion. Therefore, the depth of the recess can be reduced by reliably rolling down the recess, which is a residual flaw, without causing breakage or perforation in the steel strip during cold rolling. Therefore, it is possible to completely and surely eliminate the recesses on the surface of the cold-rolled steel strip by performing one-pass or multiple-pass unlubricated cold rolling and then performing one-pass or multiple-pass lubricated cold rolling.

The magnitude of such effects of the unlubricated cold rolling and the lubricated cold rolling according to the present invention is particularly influenced by the size of the concave portion which is a residual flaw on the surface of the hot rolled steel strip. FIG. 2 is an explanatory view showing an example of the shape of the recess 21 which is a residual flaw on the surface of the hot-rolled steel strip 20 that has been ground by the full-width surface grinding device described with reference to FIG. 2) is a cross-sectional view, and FIG. 2B is a plan view. The residual flaw 21 is indicated by a shaded portion in FIG. 2 (a) and a black-painted portion in FIG. 2 (b).

As shown in FIGS. 2 (a) and 2 (b), when the length of the recess is a (mm), the depth is b (mm), and the width is c (mm), the present invention is realized. Then, paying attention to the depth b. (I) When the depth b exceeds 0.5 mm, the hot rolling steel strip is subjected to one-pass or multi-pass unlubricated cold rolling to obtain the depth b.
Of 0.5 mm or less and satisfy the prescribed relationship shown in Table 1 among the length a, the depth b and the width c of the recess, and then apply one or more passes of lubrication cooling to the hot rolled steel strip. Rolling (ii) when the depth b is 0.5 mm or less, the length a,
It is determined whether the depth b and the width c satisfy the predetermined relationship shown in Table 1, and if they satisfy the relationship, the hot-rolled steel strip is subjected to one-pass or multiple-pass without performing unlubricated cold rolling. Lubrication cold rolling is performed, and if not satisfied, hot-rolled steel strip is subjected to 1-pass or multi-pass unlubricated cold rolling to satisfy the predetermined relationship shown in Table 1 and then 1-pass or multi-pass lubrication. Perform cold rolling.

[0038]

[Table 1]

The relationship among a, b and c shown in Table 1 is shown in FIG. In the graph shown in FIG. 6, when a ≤100, it is in the range above the circle marked by ○, when 100 <a ≤300, it is in the range above the graph by ●, and when a> 300. Non-lubricating cold rolling is finished when the respective ranges are above the graph indicated by Δ, and one pass or multiple passes of lubricating cold rolling is performed.

That is, in the present invention, in one-pass or multi-pass unlubricated cold rolling, the depth of the recessed portion, which is a residual flaw, is 0.5 mm or less, and the length a, depth b and width c of the recessed portion are set. By performing unlubricated cold rolling so as to satisfy the relationship shown in Table 1, the hot-rolled steel strip is rolled at a uniform elongation rate over the entire area regardless of the difference in the grinding amount of each surface portion of the hot-rolled steel strip. can do. Therefore, when grinding a hot-rolled steel strip, it is not necessary to make the grinding amount constant throughout the steel strip as in the conventional case, and only the portion where the residual flaw is generated is partially ground and then cold-rolled. It becomes possible.

FIG. 3 shows a surface grinding line according to the present invention capable of partially grinding the surface of the hot rolled steel strip 31.
An example of 30 is shown schematically. As shown in FIG. 3, the surface grinding line 30 according to the present invention includes a pay-off reel 37 for paying out a coil, a tension reel 38 for winding the hot-rolled steel strip 31 paid out by the pay-off reel 37 around the coil, and these. A spot grinding device 39 for the hot-rolled steel strip 31 is further added to the conventional surface grinding line having the full-width surface grinding devices 35a to 35d for grinding the entire width of the hot-rolled steel strip 31 arranged therebetween.

In the example shown in FIG. 3, the spot grinding device 39
Is (i) a primary optical flaw detection device 391 having an image processing device, which is arranged between the payoff reel 37 and the full-width surface grinding devices 35a to 35d, and (ii) a primary optical flaw detection device. An arithmetic processing unit (not shown) for processing the signal sent from the detecting device 391, and (iii) a signal from the arithmetic processing unit (not shown) arranged between the full-width surface grinding devices 35a to 35d and the tension reel 38. Primary spot grinding device 392 equipped with a drive control device that is operated by, and (iv) a secondary optical system equipped with an image processing device, which is arranged between the primary spot grinding device 392 and the tension reel 38. Defect detection device
393, (v) an arithmetic processing unit (not shown) that processes the signal sent from the secondary optical flaw detection device 393, and (vi) between the secondary optical flaw detection device 393 and the tension reel 38. And a secondary spot grinding device 394 provided with a drive control device which is operated by a signal from the arithmetic processing unit (not shown).

In FIG. 3, the hot-rolled steel strip 31 once dispensed using the pay-off reel 37 and the tension reel 38.
On the upper surface of the strip are installed full width surface grinding devices 35a to 35d arranged in series in exactly the same manner as the conventional device, and on the lower surface of the strip 31, there are four full width surface grinding devices 35a to 35d.
By arranging crimping rolls 36a to 36d corresponding to 35d and pressing the strips 31 against the grinding belts 34a to 34d which move the strips 31 when the crimping rolls 36a to 36d ascend, grinding of the entire length and width of the strip 31 is performed. In addition, the primary spot grinding device 392 and the secondary spot grinding device 394 are arranged in the downstream process of the full width surface grinding devices 35a to 35d so that the residual flaws of the hot-rolled steel strip 31 remain. Is locally and sufficiently ground to suppress or eliminate the concave portion, which is a residual flaw, and is wound around the coil by the tension reel 38.

The residual flaws are sufficiently ground by such partial grinding, and the hot-rolled steel strip is wound on the coil.
By performing unlubricated cold rolling and lubricated cold rolling in a cold rolling step (not shown), a cold rolled steel strip having no concave portion due to residual flaws generated at the stage of hot rolled steel strip 31 is manufactured. It becomes possible to do.

As described above, the spot grinding device 39 detects the residual flaws of the hot-rolled steel strip 31 which has been ground by the full-width surface grinding devices 35a to 35d, and partially grinds only the detected residual flaw occurrence portion. It is a grinding machine that can be used and need not be limited to a particular type of grinding machine. For example, a grinding device equipped with a surface flaw detection device and a general-purpose industrial robot equipped with a small grinder at the tip of a manipulator, which is installed movably in the steel strip conveying direction and in a direction orthogonal to the steel strip conveying direction, is provided. It can be illustrated.

In the case of using the grinding device of the exemplified embodiment, the grinding head which is the grinder mounting portion is provided with at least two kinds of grinding members (for example, grinding belts) for rough grinding and finish grinding, which can be switched. However, when grinding, you can select precision grinding and rough grinding,
desirable. FIG. 5 shows a grinding head which is a grinder mounting part.
FIG. 50 is a front view of 50, in which a finish grinding belt 51 for performing precision grinding and a rough grinding belt 52 for performing rough grinding are mounted rotatably and fixedly in a direction of an arrow of the grinding head 50 so as to be switchable. There is. The finish grinding belt 51 and the rough grinding belt 52 are configured so that the common motor 53 drives the respective grinding belts.

The surface grinding line according to the present invention as described above
According to 30, it is possible to reduce the grinding amount and the grinding range, so that it is possible to reduce the manufacturing cost and improve the productivity. Further, the configuration of the spot grinding device 39 will be described in more detail with reference to FIG.

FIG. 4 is a top view showing in detail a structural example of the spot grinding device 39 in the surface grinding line 30 according to the present invention shown in FIG. 3, and for the sake of convenience of explanation, the primary optical flaw detection device 42. Full width surface grinding device between the primary spot grinding device 44 and the primary spot grinding device 44 (reference numerals 35a to 35d in FIG. 3), and the payoff reel 37 and tension reel in FIG.
38, and the pressure rolls 36a to 36d are omitted.

In FIG. 4, the primary optical flaw detection device 42
Is equipped with a plurality of image processing devices 42a to 42f in series in the width direction of the hot-rolled steel strip 41, and is configured to be able to detect the generation position and degree of surface flaws in the entire hot-rolled steel strip 41. . As the optical flaw detection device 42, for example, a commercially available TV camera equipped with a detection light irradiation device can be exemplified.

Using this primary optical flaw detection device 42,
The data (the width of the surface flaw, the position in the longitudinal direction, the size, etc.) of the surface flaw generation portion is detected and stored, and this data is output to the arithmetic processing unit 43. As the arithmetic processing device 43, for example, a commercially available image processing device can be exemplified.

The arithmetic processing unit 43 stores the positions and degrees of a plurality of detected surface flaws, respectively, and of these surface flaws, the position of the surface flaw is in what order, and what kind of grinding member is used. From the viewpoint of whether surface grinding can be performed most efficiently by using, the operation details of the primary spot grinding device 44 (grinding position, grinding order, type of grinding member used, grinding time) Etc.).

It should be noted that the grinding order of the primary spot grinding device 44 in the arithmetic processing device 43 is preferably determined by the size of the surface flaw. It is empirically known that surface flaws with a large area (width x length) also have a deep depth, and such surface defects will form depressions on the surface of the cold-rolled steel strip without reliable grinding. However, even if the grinding is insufficient, it remains and forms a recess after cold rolling, but the recess is within the allowable limit as a cold-rolled steel strip. The surface flaws should be ground in the lowest order.

After the operation processing unit 43 determines the operation (grinding content) of the primary spot grinding apparatus 44, a signal is output from the arithmetic processing apparatus 43 to the drive control unit 44a to cause the primary spot grinding apparatus 44 to operate. Is commanded and the primary spot grinding device 44 is activated.

In the example shown in FIG. 4, as the primary spot grinding device 44, a traveling device in the steel strip conveying direction and the direction orthogonal thereto is provided, and is movable in the steel strip conveying direction and the direction orthogonal thereto. An example of the grinding robot 44b is an installed general-purpose industrial robot having a small grinder attached to the tip of a manipulator. In addition, as shown in FIG. 5 described above, a grinding head which is a grinder mounting portion at a tip of a manipulator of a grinding robot.
The 50 may be provided with a finishing grinding belt 51 and a rough grinding belt 52 so as to be switchable.

In FIG. 4, the primary spot grinding device 44
The grinding robot 44b, which composes, synchronizes with the hot-rolled steel strip in the steel strip conveying direction according to the operation contents (grinding position, grinding order, type of grinding belt used, grinding time, etc.) determined by the processing unit 43. The surface flaws of the hot-rolled steel strip 41 are partially ground by running, traversing in the width direction of the steel strip (traverse), and switching the grinding member (grinding belt) (selecting the grinding head).

Since the primary optical flaw detecting device 42 is basically a device for recognizing surface flaws in a planar manner, the depth of the surface flaw can be accurately measured without actually grinding. Therefore, at the stage of grinding by the primary spot grinding device 44, therefore, the relationship between the length a, the depth b and the width c of the convex portion as shown in Table 1 or the graph in FIG. 6 is satisfied. It's not easy to do. However, at the start of grinding, first grind until one of the surface defects is completely eliminated, and the grinding depth at this time is confirmed as the depth b of the convex portion. When the depth b is 0.5 mm or less, , The size of surface flaws (length a,
Grinding may be performed while controlling the width c).

In addition, the primary spot grinding device 44 is provided with a synchronous running function in the steel strip conveying direction because the primary spot grinding device 44 and the hot-rolled steel strip 41 relative to each other in the steel strip conveying direction. By performing the grinding at a speed of 0, the variation in the grinding amount caused by the relative speed between the primary spot grinding device 44 and the hot-rolled steel strip 41 is eliminated, and the disturbance factor is only the selection of the grinding member and its pressing pressure. This is to improve the accuracy of the grinding depth by

By the way, when the hot-rolled steel strip 41 is spot-ground by such a primary spot-grinding device 44, it is possible to grind a predetermined range around the surface flaw to be ground. However, because the depth of the surface flaw that is the concave portion, that is, the amount of grinding cannot be predicted, the surface flaw is left behind (insufficient grinding), and the length a of the concave portion indicated by the graph in Table 1 or FIG. The relationship between the height b and the width c may not be satisfied.

Therefore, as shown in FIG. 4, in the surface grinding line 40 according to the present invention, as a countermeasure against such a surface flaw left by the primary spot grinding device 44, the image processing devices 45a to 45e are hot rolled steel. Secondary optical flaw detection device 45, which is provided in series in the width direction of the band 41, secondary optical flaw detection device
An arithmetic processing unit 46 connected to 45, and an arithmetic processing unit 46
Drive controller 47a and grinding robot 47
A secondary spot grinding device 47 having b and is installed in the downstream process. These configurations consist of the primary spot grinding device 4
4, exactly the same as the primary optical flaw detection device 42 etc.,
Estimate the depth of unremoved flaws after grinding by the primary spot grinding device by measuring the size of the remaining flaws on the unremoved concave surface (a, b) with the secondary optical flaw detection device, Spot grinding is performed based on this.

In the grinding robot 47b, as shown in FIG.
As shown in, it is desirable that the grinding head 50, which is a grinder mounting portion at the tip of the manipulator, is provided with a finish grinding belt 51 and a rough grinding belt 52 so that the grinding head can be freely adjusted because the grinding degree can be adjusted freely.

Further, while six image processing devices 42a to 42f in the primary optical defect detection device 42 are installed, an image processing device in the secondary optical defect detection device 45 is provided.
45a to 45e are 5 groups, but this has no particular meaning, and may be the same number or a large number.

That is, the length a, the depth b, and the width c of the recess, which are residual flaws after grinding by the primary spot grinding device 44, are measured, and it is determined whether the depth b of the recess is 0.5 mm or less. To judge. (I) When the depth b exceeds 0.5 mm, the hot-rolled steel strip 41 is subjected to non-lubricating cold rolling to reduce the depth b to 0.5 mm or less and the recess length a. ,
After satisfying the predetermined relationship shown in Table 1 or the graph in FIG. 6 between the depth b and the width c, the hot rolled steel strip 41 is subjected to lubrication cold rolling, and (ii) the depth b is 0.5 mm or less. In the case of, it is judged whether or not the length a, the depth b and the width c satisfy the predetermined relations shown in Table 1, and when they satisfy, the hot rolled steel strip is subjected to unlubricated cold rolling. Without performing the lubrication cold rolling, if not satisfied, perform the non-lubrication cold rolling on the hot rolled steel strip to satisfy the predetermined relationship shown in Table 1 or the graph in FIG. To do.

As described above, according to the present invention, a method for cold rolling a steel strip having no recesses due to residual flaws in the hot rolled steel strip, and a hot rolled steel strip used as a rolling material for this cold rolling are provided. To provide the surface grinding line of
In particular, surface defects easily occur due to seizure during hot rolling,
When the generated surface flaw is ground using, for example, a full-width surface grinding device consisting of a grinder, a part of the surface flaw remains as a recess and a cold rolling method of the hot rolled stainless steel strip, and this cold rolling is performed. It was possible to provide a surface grinding line for hot-rolled stainless steel strip used as a raw material. Further, the present invention will be described in detail with reference to examples, but this is an example of the present invention and the present invention is not limited thereto.

[0064]

[Example 1] Hot rolled stainless steel strip (SUS304, thickness: 3.2 m
m, width: 1000 mm) was partially ground by the surface grinding line shown in FIGS. Thus, the hot rolled stainless steel strip having the recesses, which are recesses, on the surface was measured, and the lengths a, the depths b and the widths c of the recesses were measured.

As Inventive Example 1 and Inventive Example 2, the unlubricated cold rolling with the reduction amount shown in Table 2 was performed, and then the lubricating cold rolling with the reduction amount shown in Table 2 was performed to obtain a sheet thickness of 0.8. mm cold-rolled stainless steel strip manufactured, cold drawing reduction rate
(%) And perforation rate (%) were measured.

On the other hand, as a comparative example, a hot-rolled stainless steel strip manufactured in exactly the same manner was subjected to lubrication cold rolling with a rolling reduction shown in Table 2 without performing unlubricated cold rolling to obtain a sheet thickness of 0.8. mm cold-rolled stainless steel strip was produced, and the reduction rate (%) and the rate of perforation (%) during cold rolling were measured. The results are summarized in Table 2. In addition, in the invention examples 1 and 2, and the comparative example, the number of measurements was 45 times.

[0067]

[Table 2]

In the invention example 1 and the invention example 2, no recess was formed on the surface of the cold-rolled steel strip after unlubricated cold rolling and lubricated cold rolling. On the other hand, in the comparative example, as shown in Table 2, even if the recess size satisfies the condition specified in the present invention, the non-lubricating cold rolling is not performed first and then the lubrication cold rolling is not performed. If so, drawing and perforation will occur during lubrication cold rolling.

According to the present invention, by performing unlubricated cold rolling and then lubricated cold rolling, it is possible to produce a cold stainless steel strip having no recesses without causing drawing or perforation. It was

[0070]

[Example 2] Regarding the hot-rolled stainless steel strip in Example 1, the lengths a and the depths b of various recesses on the surface after grinding
And the width c were measured, and a follow-up investigation was carried out as to whether or not these recesses disappeared after unlubricated cold rolling and lubricated cold rolling.
The results are summarized in the graph in FIG. 7.

In the graph shown in FIG. 7, white marks indicate that the recesses were not present on the surface of the cold rolled steel strip, and black marks indicate that the recesses were present. The crosses in the graph shown in FIG. 7 indicate fractures due to perforation during the lubrication cold rolling. From the graph shown in FIG. 7, it can be seen that the cold-rolled steel strip using the hot-rolled steel strip satisfying the preferred range of the present invention as the rolling material has no recessed portion at all.

[0072]

As described in detail above, according to the present invention, there is provided a cold rolling method for a steel strip and a surface grinding line for a hot rolled steel strip used as a rolling material for this cold rolling. In particular, in particular, surface defects are likely to occur due to seizure during hot rolling, and when the generated surface defects are ground using, for example, a full-width surface grinding device composed of a belt grinder, a part of the surface defects is recessed. It becomes possible to provide a cold rolling method for the remaining hot-rolled stainless steel strip and a surface grinding line for the hot-rolled stainless steel strip used as a rolling material for this cold rolling. It was possible to manufacture a cold-rolled steel strip having no recesses due to residual flaws without causing perforation or drawing during cold rolling.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing a situation where cold rolling is performed by a cold rolling roll 12 on a hot rolled steel strip 11 having residual flaws 13 and 14 even after grinding with a grinder. a)
Shows the situation in which lubrication cold rolling is performed, and Fig. 1 (b) shows the situation in which non-lubrication cold rolling is performed.

FIG. 2 (a) and FIG. 2 (b) are cross-sectional views of an example of a hot-rolled steel strip that remains after a surface flaw is ground and a part of the surface flaw remains as a residual flaw. It is a figure and a top view.

FIG. 3 is an explanatory view schematically showing an example of a surface grinding line 30 according to the present invention capable of partially grinding the surface of a hot rolled steel strip 31.

4 is a top view showing in detail a configuration example of a spot grinding device 39 in the surface grinding line 30 according to the present invention shown in FIG.

FIG. 5 is a front view of a grinding head 50 which is a grinder mounting portion.

FIG. 6 is a graph showing the relationship between the length a, the depth b, and the width c of the recess defined by the present invention.

FIG. 7 is a graph showing the results of Example 2.

FIG. 8 (a) is an explanatory view showing an example of a full-width surface grinding device 85 used when grinding a hot-rolled steel strip, and FIG. 8 (b) shows four full-width surface grinding devices. FIG. 7 is an explanatory view showing a surface grinding line 80 of a hot rolled steel strip in which grinding devices 85a to 85d are arranged.

[Explanation of symbols]

11: Hot-rolled steel strip 12: Cold rolling rolls 13, 14: Residual flaw (recess) 15: Rolling oil 20: Hot-rolled steel strip 21: Recess 30: Surface grinding line 31: Hot-rolled steel strip 32a to 32d: Drive Rolls 33a to 33d: Drive rolls 34a to 34d: Grinding belts 35a to 35d: Full-width surface grinding devices 36a to 36d: Crimping rolls 37: Payoff reels 38: Tension reels 39: Spot grinding devices 391: Primary optical flaw detection device 392: Primary spot grinding device 393: Secondary optical flaw detection device 394: Secondary spot grinding device 40: Surface grinding line 41: Hot rolled steel strip 42a to 42f: Image processing device 42: Primary optics Defect detection device 43: Arithmetic processing device 44: Primary spot grinding device 44a: Drive control device 44b: Grinding robot 45a to 45e: Image processing device 45: Secondary optical defect detection device 46: Arithmetic processing device 47: Secondary spot grinding machine 47a: Drive controller 47b: Grinding robot 50: Grinding head 5 1: Finishing grinding belt 52: Rough grinding belt 53: Common motor 80: Surface grinding line 81: Hot rolled steel strip 82, 82a to 82d: Driving rolls 83, 83a to 83d: Driving rolls 84, 84a to 84d: Grinding belt 85 , 85a to 85d: Full-width surface grinding machine 86, 86a to 86d: Crimping roll 87: Payoff reel 88: Tension reel

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[Procedure amendment]

[Submission date] May 11, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction content]

Since the primary optical flaw detecting device 42 is basically a device for recognizing the surface flaw in a planar manner, the depth of the surface flaw can be accurately measured without actually grinding. Therefore, the primary spot grinding device 44
The length of the recess as in the stage of grinding shown graphically in Table 1 or 6 described above by a, to satisfy the relation of depth b and width c is not easy. However, performs a grinding until one of surface defects to increase at the time of grinding start is completely eliminated in advance to check the grinding depth at this time as the depth b of the recess,
When the depth b is 0.5 mm or less, grinding may be performed while controlling the size of the surface flaw (length a, width c) so that the relationship shown in the graph in Table 1 or FIG. 6 is obtained.

Claims (5)

[Claims] 1. A cold rolling method of a hot-rolled steel strip, wherein a part of the surface flaw is left as a residual flaw which is a recess after grinding the surface flaw. A cold rolling method for hot-rolled steel strip, characterized in that the recesses are eliminated by performing non-lubricating cold rolling in multiple passes or multiple passes and then performing single-pass or multiple-pass lubricating cold rolling. 2. A cold rolling method for hot-rolled steel strip, wherein after the surface flaw is ground, a part of said surface flaw becomes a residual flaw that is a concave portion, and (i) the depth of said concave portion. If the depth b exceeds 0.5 mm, the hot rolled steel strip may be subjected to one pass or multiple passes of unlubricated cold rolling to reduce the depth b of the recess.
The hot-rolled steel strip has a thickness of 0.5 mm or less and satisfies the relationship shown in the discrimination table previously obtained among the length a of the recess, the depth b of the recess and the width c of the recess, and then Performing lubrication cold rolling in multiple passes or in multiple passes, and (ii) if the depth b of the recess is 0.5 mm or less, the length a of the recess is
It is determined whether the depth b of the recess and the width c of the recess satisfy the above relationship, and when they satisfy the relationship, one pass or a plurality of passes without performing unlubricated cold rolling on the hot rolled steel strip. Lubrication cold rolling of the pass is performed, and when not satisfied, the hot rolled steel strip is subjected to one pass or multiple passes of unlubricated cold rolling to satisfy the above relationship, and then one pass or multiple passes of lubrication cold rolling. A cold rolling method for a hot-rolled steel strip, characterized in that the recesses are eliminated by rolling. 3. A pay-off reel for paying out a coil, a tension reel for winding a hot-rolled steel strip paid out by the pay-off reel on a coil, and the heat-off reel arranged between the pay-off reel and the tension reel. A surface-grinding line of a hot-rolled steel strip provided in combination with a full-width surface grinding device for grinding the full-width of a strip of steel, further comprising a hot-rolled steel strip between the full-width surface grinding device and the tension reel. A surface grinding line for hot-rolled steel strips, which is equipped with a spot grinding device. 4. A payoff reel for paying out a coil, a tension reel for winding the hot-rolled steel strip paid out by the payoff reel on a coil, and a heat reel arranged between the payoff reel and the tension reel. A surface grinding line for a hot-rolled steel strip equipped with a combination of a full-width surface grinding device for grinding the entire width of the steel strip, further comprising (i)
A primary optical flaw detection device provided with an image processing device, arranged between the pay-off reel and the full-width surface grinding device; and (ii) a signal output from the primary optical flaw detection device. A primary spot grinding device having a drive control device that is operated by a signal from the arithmetic processing device and is disposed between the full width surface grinding device and the tension reel. And (iv) a secondary optical flaw detection device that is arranged between the primary spot grinding device and the tension reel and that includes an image processing device, and (v) the secondary optical flaw. An arithmetic processing device for processing a signal output from the detection device, and (vi) disposed between the secondary optical flaw detection device and the tension reel,
A surface grinding line for a hot-rolled steel strip, comprising a secondary spot grinding device in combination with a drive control device that operates in response to a signal from the arithmetic processing device. 5. The hot-rolled steel strip according to claim 4, wherein the secondary spot grinding apparatus is provided with at least two kinds of grinding members for rough grinding and finish grinding, which are switchable. Surface grinding line.