JP2000052124A - Hot cutting method for rolled steel material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a finish rolling continuously by cutting a hot rolled steel material after rough rolling in a rolling line to descale it and joining the cut steel materials. SOLUTION: In this cutting method for joining the end parts of hot steel materials for performing a continuous rolling, the rear end of a preceding steel material and the top of a following steel material are arranged by providing a clearance vertically in a face parallel to the rolling line, and a rotating cutting tool, the edge-pitch (p) of the cutting edge 24 of which satisfies an inequality: p>2W+f W is the cutting width (mm) cut by a cutting edge, of a rolled steel material, (f) is a feed (mm/r. cutting edge) per a cutting edge/one rotation of a rotating cutting tool} is inserted into the clearance to cut only either of the preceding steel material or the following steel material. Besides, for the cutting by means of the rotating cutting tool, amaximum depth (fe) of cut of 0.2 mm is desirable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for descaling a joint surface in a continuous hot rolling line of steel material in order to efficiently and surely join a rolled steel material (for example, a red-hot steel material having a temperature of 900 ° C. or more). Hot cutting method for

[0002]

2. Description of the Related Art In steel manufacturing plants, continuous production processes are being vigorously promoted for the purpose of energy saving, improvement of product yield, improvement of productivity, and the like. Among them, continuation of the hot rolling process for producing a hot-rolled steel sheet (hot coil) is one of the important issues.

[0003] In recent years, between a rough rolling mill and a finishing rolling mill, a preceding rough-rolled steel material (hereinafter, referred to as a preceding steel material) and a subsequent rough-rolled steel material (hereinafter, referred to as a succeeding steel material) are joined. A method of continuously performing finish rolling has been proposed.

[0004] For example, a method in which a superposed portion of a hot-rolled steel sheet is heated in a reducing flame atmosphere to reduce the scale and press the entire width of the hot-rolled steel sheet in the thickness direction (see Japanese Patent Application Laid-Open No. 6-312277). ). Also, steel plates with thick scales,
Alternatively, in the case of a steel sheet in which a scale having a composition that is not easily reduced is formed, a method of mechanically descaling with a rotary cutting tool or the like and pressing the same (Japanese Patent Laid-Open No. 6-335785,
8-19804, 9-57302, and the like).

FIG. 9 is a diagram showing an outline of a continuous hot rolling facility in which a hot press apparatus is arranged. The steel slab 9 is rolled by the rough rolling mill 1 to become a rolled steel S, which is once wound into a coil in the intermediate coiler 2. Then, it is rewound before being sent to the finishing mill group 6, the winding habit of the coil is corrected by the leveler 3, and the defective portion at the end is cut by the crop shear 4. Then, after pressing the rear end of the preceding steel S1 and the front end of the following steel S2 in the hot pressing device 5 that runs, finish rolling is performed by the finishing rolling mill group 6, and the roll is wound up by the down coiler 8. . Then, it is cut by the high-speed shear 7 to form a hot-rolled steel sheet coil.

FIG. 10 is a longitudinal sectional view showing a hot pressing apparatus using a rotary cutting tool.

The joining is performed in the following steps. First, when the rear end of the preceding steel material S1 comes to a predetermined position (the position of the press contact press 10), the steel material is fixed by the clamp device 11, and the gantry 12 is fixed.
Is raised by a lifting cylinder 14 and pushed up to a position where it can be cut by a cylindrical rotary cutting tool 15. Next, when the trailing steel material S2 is advanced and its tip comes to the position of the lower mold 16 (position overlapping the rear end of the preceding steel material), the trailing steel material is fixed by the clamp device 11. Thereafter, the burner 17 is burned to move the cylindrical rotary cutting tool 15 in the direction indicated by the arrow as a reducing flame atmosphere around the ends of the leading steel S1 and the trailing steel S2 to cut the ends of the respective steels. . When the cutting is completed, the rotary tool is retracted, and the gantry 12 of the preceding steel material is lowered simultaneously with the press-contact press 10 and pressed. The hot pressing device 5 travels in the rolling direction by traveling rollers 18.

[0008] There are two methods of hot joining, namely, a method of superimposing them according to the shape of the joint part of the steel plates and a method of performing butt joining.

FIG. 11 is a view showing a mode of joining, and FIG.
(C) is a diagram showing a situation in which steel plates are overlapped and pressed in the thickness direction to join them, and (d) is a diagram showing a situation in which steel plates are butted and pressed in the longitudinal direction to join them.

As shown in FIG. 11 (a), the joining method is performed by diagonally cutting the joint portion, by cutting stepwise as shown in FIG. 11 (b), or by cutting as shown in FIG. 11 (c). With a groove-shaped notch. In both cases, the steel sheet S1, S
2 Hold the cutting surfaces 20 and 21 together and press
The pressure is reduced in the thickness direction of the steel. Simultaneously with the reduction, one of the gripping devices (in this case, the gripping device 19 for the succeeding steel plate) is moved according to the amount of reduction, or the gripping device is opened. At the time of cutting and joining, a reducing flame is blown from the burner 17 to prevent oxidation.

[0011] As shown in Fig. 11 (d), the method of butting is as follows: after cutting or cutting, the steel materials S1 and S2 are gripped by the gripping device 19, and the cut portions or cut surfaces 20, 21 are butted on the same plane. The holding device is moved in a direction opposite to the longitudinal direction of the steel plate, and is pressed and joined. During cutting and joining, a reducing flame is blown from the burner 17 to prevent oxidation.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for cutting under a reducing atmosphere in order to descaling a surface to be joined of a high-temperature steel material.

[0013]

The gist of the present invention resides in a hot cutting method for performing descaling by cutting.

When continuous hot rolling is performed by joining the ends of two rolled steel materials, a rear end of the preceding steel material and a front end of the succeeding steel material are provided with a gap above and below a plane parallel to the rolling line. A hot cutting method of a rolled steel material in which a rotary cutting tool having a cutting edge pitch p satisfying the following formula is inserted into this gap and only one of a preceding steel material and a succeeding steel material is cut.

P> 2W + f Here, W is a cutting width (m) of a rolled steel material cut by one blade.
m) and f are feed amounts per rotation of the rotary cutting tool per blade
(mm / r · blade).

The above-mentioned rotary cutting tool has a conical or cylindrical shape, and it is desirable that the ridgeline of the cutting edge attached to the circumferential surface of the arbor or the sleeve is attached so as to be inclined with respect to the axial direction of the arbor. .

Further, the cutting by the rotary cutting tool is
It is desirable that the maximum cutting thickness (fe) of the cutting edge be 0.20 mm or more.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The cutting method for descaling according to the present invention uses a cylindrical or conical rotary cutting tool for removing scale from a rolled steel material, and is provided on a circumferential portion of an arbor or a sleeve. This is a method in which the cutting edge pitch of the cutting blade is set to be larger than the sum of twice the width of the rolled steel material cut and the feed amount per blade per rotation of the cutting tool.

FIG. 1 is a perspective view of a cylindrical rotary cutting tool, in which (a) is a rotary cutting tool having a cutting blade mounted on an arbor, and (b) is a rotary cutting tool having a cutting sleeve mounted on a divided sleeve. It is a cutting tool. These cylindrical rotary cutting tools 15 arrange the axis of the arbor 22 in parallel with the width direction of the steel material, and rotate the axis to move the steel material in an oblique direction of the thickness of the steel material, thereby cutting the end of the steel material obliquely. I do.

The cylindrical rotary cutting tool 15 may have a cutting blade 24 directly attached to the arbor 22, as shown in FIG.
Further, as shown in FIG. 1 (b), a sleeve 23 may be fitted to the arbor, and a cutting blade may be attached to the sleeve. If the arbor is long, the sleeve may be divided into a plurality (three in the figure). This is to shorten the sleeve to facilitate mounting of the cutting blade, and to facilitate machining and repair. The attachment of the sleeve to the arbor employs a key method, a screw method, a shrink fit method, or the like which is usually performed.

FIGS. 2A and 2B are views showing a situation in which a steel material is obliquely cut by using a cylindrical rotary cutting tool. FIG. 2A shows a case where nine cutting blades are provided, and FIG. 2B shows a case where eight cutting blades are used. (C)
Is a case having 12 cutting blades. In both cases, the cylindrical rotary cutting tool is arranged with its axis parallel to the width direction of the rolled steel material, and while rotating, feeds obliquely in the thickness direction of the rolled steel material as shown by the arrow and moves by F, thereby rolling up and down. The corners of steel are cut simultaneously in the width direction.

When the number of cutting blades is nine, as shown in FIG. 2 (a), the rotary cutting tool starts cutting the lower steel when the rotation center comes to the position X, and comes to the position Y. When the cutting of the upper steel material starts. When the position of Z is reached, the cutting of the lower steel material is terminated. Therefore, the upper and lower steel materials are simultaneously cut from Y to Z, but the lower cutting amount is smaller than the upper cutting amount. In addition, FIG.
As is clear from 2 (c), the same applies to the case where the number of cutting blades is eight or twelve.

As shown by the bold line in FIG. 2A, when three cutting blades are used, the upper and lower steel materials are not cut at the same time while cutting from Y to Z. Further, as is clear from FIG. 2 (b) or FIG. 2 (c), the same applies to the case where four or six cutting blades are used. Therefore, in order not to cut the upper and lower steel materials at the same time, the arrangement of the cutting blades needs to be larger than twice the cutting width W of the rolled steel material as shown in FIG. 2 (b).

FIGS. 3A and 3B are views showing a rotary cutting tool which performs oblique cutting while moving the rotary cutting tool in the width direction of the rolled steel material, wherein FIG. 3A shows a conical rotary cutting tool, and FIGS. It is a figure showing a cylindrical rotary cutting tool. The cylindrical rotary cutting tool shown in FIGS. 3 (b) and 3 (c) is a disk-shaped rotary cutting tool having a shorter arbor than the rotary cutting tool shown in FIG.
The rotary cutting tool shown in FIGS. 3 (a) and 3 (b) moves in the width direction of the steel by tilting its axis with respect to the rolling direction of the steel, but the rotary cutting tool shown in FIG. 3 (c) Moves in the width direction of the steel with its axis parallel to the rolling direction of the steel. In any case, the sleeve 23 is attached to the arbor 22.

FIGS. 4 and 5 are schematic views showing a state in which the cylindrical rotary cutting tool is moved in the width direction of the steel material for cutting. In each case, cutting is performed while moving the rotary cutting tool at the maximum cutting depth t in the direction of the black arrow and moving it at F (mm / min), and the cutting blade of B1 cuts the area surrounded by b1, b2 and b3. , B2 cut the area surrounded by b4, b5 and b6.

FIG. 4A shows that the number of cutting blades is six.
FIG. 4 (b) shows the case of a rotary cutting tool having four cutting blades, FIG. 5 (c) shows the case of a rotary cutting tool having three cutting blades, and FIG. As shown in FIG. 4 (a), when cutting with a rotary cutting tool having six cutting blades, when cutting blade B1 starts cutting from the position of b1,
Cutting blade B2 has already finished cutting. Then, when the cutting blade of B3 starts cutting from the position of b4, the cutting blade of B4
, But no cutting is performed here. Therefore, in this case, the upper and lower cutting blades do not cut at the same time. Similarly, as shown in FIGS. 4 (b), (c) and (d), even when the number of cutting blades is 4, 3, and 2, it is not possible for the upper and lower cutting blades to perform cutting simultaneously. Absent.

On the other hand, in FIG. 5, FIG. 5A shows nine cutting blades, FIG. 5B shows eight cutting blades, FIG. 5C shows seven cutting blades, and FIG.
Is the case of a rotary cutting tool having five cutting blades.

As shown in FIG. 5 (a), in the case of having nine cutting blades, when the cutting blade B1 starts cutting from the position of b1, the cutting blade B2 has already started cutting from the position of b4. Yes,
The upper and lower cutting blades perform cutting simultaneously. this is,
This is because the pitch p of the cutting edge of the cutting blade is smaller than twice the value of the cutting width W.

As shown in FIG. 5 (b), when similar cutting is performed with a rotary tool having eight cutting blades, when the cutting blade B1 starts cutting from the position of b1, the cutting blade B2 starts cutting. I'm done. However, when the cutting blade of B3 starts cutting from the position of b4, the cutting blade of B1 is at the position of b8 and is still cutting. Also in this case, the upper and lower cutting blades simultaneously perform cutting.

As shown in FIG. 5 (c), when similar cutting is performed with a rotary tool having seven cutting blades, the cutting blades B1 and B2 simultaneously start cutting. This is because the pitch p of the cutting edge is equal to the cutting width 2W of the rolled steel material.

As shown in FIG. 5 (d), when similar cutting is performed with a rotary tool having five cutting blades, the pitch p of the cutting edge of the cutting blade is larger than twice the cutting width W. B2 cutting blade is b
When starting the cutting from the position 4, the cutting blade of B1 is at the position of b9 and the cutting is still performed. Also in this case, the upper and lower cutting blades simultaneously perform cutting.

As described above, when the number of cutting blades of the cylindrical rotary tool is increased with respect to the diameter of the cylindrical portion, the pitch of the cutting edges is reduced, and the upper and lower cutting blades are simultaneously cut.

Since the tool is moving in the width direction, it is necessary to consider the amount (feed amount) of the cutting edge pitch p. As shown in FIG. 4, the pitch p is twice the cutting width W of the rolled steel material and the feed amount. And the two steel materials must not be cut at the same time.

FIG. 6 is a diagram showing the arrangement of the cutting blades.
(a) is a figure which shows the rotary cutting tool which made the edge line of the cutting edge parallel to the axis of the arbor, and (b) shows the rotary cutting tool which made the edge line of the cutting edge inclined to the axis of the arbor. As shown in the figure, in any case, it is desirable to mount the cutting blades so that they slightly overlap in the circumferential direction (in a staggered manner). Thereby, the impact load at the time of cutting can be reduced, and the cut surface can be made smooth.

As the material of the cutting blade, a cemented carbide having a high temperature and a high altitude is used. Cemented carbide is WC (tungsten carbide)
Is obtained by sintering a carbide such as TiC (titanium carbide) and Al ₂ O ₃ (alumina) with Co as a binder (for example, TiC: 15% by weight, Co: 5% by weight, balance WC). .

Next, a cutting method using these rotary cutting tools will be described.

In the hot cutting method using the rotary cutting tool according to the present invention, the maximum cutting thickness of the cutting edge is set to 0.20 mm or more.

FIG. 7 is a schematic diagram for explaining a cutting situation with a rotary cutting tool. This drawing shows a cutting portion of one cutting blade when a rotary cutting tool having a cutting edge with a rotating diameter of D is used, and a cutting depth (thickness) is t, and a horizontal feed per rotation is f. ing. The “maximum cutting depth of the cutting edge” in the present invention means “maximum thickness fe of a thick line portion” shown in FIG. 8 and can be approximately calculated by the following equation.

Fe = f ・ sinψaψa can be calculated by the following equation.

[0040]

(Equation 1)

FIG. 8 is a diagram showing the relationship between the maximum cutting depth and the specific cutting resistance. This figure shows a plate thickness of 30 mm and a plate width of 3
00mm, low carbon steel plate with length of 1000mm and cutting edge diameter 308m
m, using a rotary cutting tool with a length of 350 mm, cutting depth t
(1.0 to 6.5 mm) and the cutting force when the temperature (700 ° C. to 1100 ° C.) of the steel sheet was changed.

As is apparent from FIG. 8, when the maximum cutting depth fe per tooth is 0.2 mm or more, the specific cutting resistance value is stabilized at 10 kg / mm ² or less regardless of the temperature of the steel sheet. Therefore, in the present invention, the maximum cutting thickness per blade is 0.
2 mm or more.

[0043]

[Example 1] [Example 1] A steel plate having a thickness of 30 mm, a width of 300 mm, and a length of 1000 mm (C: 0.1% by weight, Si: 0.5% by weight, Mn: 1.2%)
% By weight) was heated to 1250 ° C., and a bonding test was performed using a hot pressing apparatus shown in FIG.

Cutting and joining tests were performed using a cylindrical rotary cutting tool as shown in FIG. This rotary cutting tool fits a sleeve with an outer diameter of 300 mm and a length of 320 mm into the arbor, and nine cutting blades (4 mm in height and 25.4 mm in width) are staggered around the outer periphery of the sleeve. They are mounted in parallel.

The cutting conditions were a rotation speed of 1500 rpm and a feed speed.
The slant cutting was performed at 12000 mm / min with a 30 mm overlap margin at a 1/3 gradient.

Prior to cutting, a direct flame reducing flame was sprayed on the cutting portion, and cutting was performed in a reducing atmosphere. For the reducing flame, a burner of the mixing method in the nozzle is arranged in the width direction of the steel plate, and LPG gas (6 Nm ³ / hr) is passed through a ring-shaped slit nozzle.
A mixed gas of oxygen-enriched air having an oxygen concentration of 60% (air ratio m = 0.6) was burned to generate gas. The air ratio m is a value obtained by dividing the amount of air actually used by the amount of air necessary for complete combustion.

After cutting, the cut portions were overlapped while blowing the reducing flame, pressed in the thickness direction of the steel plate using a 300-ton press, and pressed down until the overlapped portion became substantially equal to the original thickness, and joined. The pressure required for joining at this time is 210
Tons.

After joining, the specimen was cooled and a tensile test specimen (width 15 mm, thickness 30 mm, length 400 mm) was collected from the joint and the base material.
When a tensile test was performed at room temperature, all fractured at the base material. The breaking strength was 250-300 N / mm ² . As a result of microscopic observation of the cross section of the joint, no harmful oxides or inclusions were observed at the joint interface.

When the temperature of the steel material reached 1000 ° C. after the pressure welding, three finish rolling mills were used to obtain 40% and 35%, respectively.
% And a rolling rate of 30% and a tension of about 3.0 kgf / mm ² were rolled in the same manner as before to produce a coil having a thickness of 8.2 mm.

Example 2 Cutting and pressure welding tests were performed using the rotary cutting tool shown in FIG. 3 (a). This rotary cutting tool,
Two conical sleeves with a large outside diameter of 300 mm, a small outside diameter of 150 mm and a length of 180 mm are fitted into the arbor, and seven cutting blades (4 mm high and 63 mm wide) are fitted around the outer periphery of the sleeve. Are mounted parallel to the axis. The axis of the arbor of the rotary cutting tool was inclined 35 ° from the steel material transfer line and moved in the width direction of the steel material.

A test was conducted under the same cutting conditions and joining conditions as in Example 1, and the same results as in Example 1 were obtained.

[0052]

According to the rotary cutting tool of the present invention, the properties of the cutting surface are stabilized by setting the pitch of the cutting blade to be greater than twice the cutting blade and the feed amount per rotation of the tool.
Thereby, the joining of the rough-rolled steel material becomes sufficient, and continuous rolling can be performed without breaking in the next finish rolling.

[Brief description of the drawings]

FIG. 1 is a perspective view of a cylindrical rotary cutting tool, wherein (a) is a rotary cutting tool having a cutting blade attached to an arbor, and (b) is a rotary cutting tool having a cutting blade attached to a divided sleeve. is there.

FIGS. 2A and 2B are diagrams showing a state in which a steel material is obliquely cut using a cylindrical rotary cutting tool, wherein FIG. 2A shows a case having nine cutting blades, FIG. (c) is a case where there are 12 cutting blades.

FIG. 3 is a view showing a rotary cutting tool that performs oblique cutting while moving the rotary cutting tool in the width direction of a rolled steel material, where (a) is a conical rotary cutting tool, and (b) and (c) are cylindrical rotary tools. It is a figure showing a cutting tool.

FIG. 4 is a schematic diagram illustrating a state in which a cylindrical rotary cutting tool is moved in a width direction of a steel material to perform cutting.

FIG. 5 is a schematic diagram showing a state in which a cylindrical rotary cutting tool is moved in the width direction of a steel material to perform cutting.

6A and 6B are diagrams showing the arrangement of cutting blades, wherein FIG. 6A is a rotary cutting tool with a ridge line of a cutting edge parallel to an arbor axis, and FIG. 6B is a rotary cutting with a ridge line of a cutting edge inclined to an arbor axis. It is a figure showing a tool.

FIG. 7 is a schematic diagram for explaining a cutting situation with a rotary cutting tool.

FIG. 8 is a longitudinal sectional view showing a hot pressure welding device using a rotary tool.

FIG. 9 is a view showing an outline of a hot continuous rolling facility in which a hot pressing device is arranged.

FIG. 10 is a longitudinal sectional view showing a hot pressure welding device using a rotary tool.

FIGS. 11A to 11C are views showing a joining mode, in which FIGS. 11A to 11C show a situation in which steel sheets are overlapped and pressed in the thickness direction and joined, and FIG. It is a figure which shows the situation which joins by pressing in a longitudinal direction.

[Explanation of symbols]

 1: Rough rolling mill Intermediate coiler 3. Leveler 4. Crop shear 5. Hot pressure welding device 6. Finishing mill group 7. High speed shear 8. Down coiler 9. Slab 10． Pressing press 11． Clamping device 12. Mount 13. Table roller 14. Lifting cylinder 15． Rotary cutting tool 16． Lower mold 17． Burner 18. Running roller 19. Gripping device 20,21. Cutting surface 22. Arbor 23. Sleeve 24. Cutting blade

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Koichi Sakamoto 4-33, Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Inside Sumitomo Metal Industries, Ltd. (72) Inventor Shigeru Yagisawa 4-chome, Kitahama, Chuo-ku, Osaka City, Osaka Prefecture No.5-33 Sumitomo Metal Industries Co., Ltd. (72) Inventor Norio Iwanami No. 1 Shinnakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Ishikawa Shima-Harima Heavy Industries Co., Ltd. Yokohama Engineering Center (72) Inventor Nobuhiro Tasoe Koto, Tokyo (19) Inventor Shiro Nagata 1-chome, Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Pref. Hama Sanki 1-1-1, Kunyokita, Itami-shi, Hyogo, Japan Sumitomo Electric Industries, Ltd.

Claims (3)

[Claims] When performing continuous hot rolling by joining the ends of two rolled steel materials, a rear end of a preceding steel material and a front end of a succeeding steel material are vertically separated by a plane parallel to a rolling line. A rotary cutting tool having a cutting edge pitch p satisfying the following formula is inserted into this gap, and only one of a preceding steel material and a succeeding steel material is cut. Cutting method. p> 2W + f where W is the cutting width (m) of a rolled steel material cut by one blade.
m) and f are feed amounts [mm / (r. blade)] per one rotation of the rotary cutting tool per blade. 2. The rotary cutting tool according to claim 1, wherein the rotary cutting tool has a conical or cylindrical shape, and a ridgeline of a cutting edge mounted on a circumferential surface of the arbor or the sleeve is mounted so as to be inclined with respect to an axial direction of the arbor. The method for hot-cutting a rolled steel material according to claim 1, wherein: 3. The hot cutting method for a rolled steel material according to claim 1, wherein the cutting with the rotary cutting tool has a maximum cutting depth (fe) of the cutting edge of 0.20 mm or more.