JP3058311B2 - Descaling method for hot rolled steel - Google Patents

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 tandem-rolled hot steel.

[0002]

2. Description of the Related Art A number of methods and devices for descaling during hot rolling of steel have been proposed and implemented. As an example, Japanese Patent Application Laid-Open No. 54-74258 discloses an apparatus entitled "Hot rolling installation of steel". This equipment is equipped with a water cooling device for exfoliating the scale of the heated steel material on the exit side of the heating furnace, and then arranges a high-pressure water jet descaler and a hot rolling machine in this order to completely remove the primary scale and remove scale flaws. The surface scale of the heated steel is cooled at a high temperature by cooling spray between the heating furnace and the rolling mill, the scale is raised from the steel surface, and the descaling unit is descaled by high-pressure water using a descaler to the rolling equipment. This is a device that completely removes scale from the steel surface before entering. However, generally, only the high-pressure water injection descaler provided on the exit side of the heating furnace is used.

[0003]

The descaling apparatus as described above finally removes scale by injecting high-pressure water (equivalent to 100 kgf / cm ² ) in a spray form onto the heated steel material. A spray device for cooling the surface scale of the heated steel material is also required in the preceding stage, and the equipment becomes large-scale, so that initial costs and running costs are large, and there are also problems such as restrictions on the equipment position. If the equipment is not sufficient and the scale remains on the steel material, the roll life will be shortened due to roll wear and the generation of flaws due to the scale getting into the product surface will of course cause problems. The challenge was to develop a highly efficient descaling method for equipment.

[0004]

SUMMARY OF THE INVENTION The present invention is over deformed complete site from the vicinity of deformation starting position of the material during rolling, water
Alternatively, a mixed flow of water and air is sprayed, and the difference in shrinkage between the heated steel material and the surface scale due to the cooling effect, and the difference in the deformation mode between the scale and the steel material in the processing after cooling, the scale There is a highly efficient descaling method in which peeling is promoted and peeling scale is removed by spraying at the same time.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the embodiment shown in FIG. The figure shows a state where the heated steel material 1 is fed in the direction of the arrow and is rolled by the rolling rolls 2 and 2 '. Although not shown, a number of rolling rolls are arranged in tandem from the heating furnace, and the steel material exiting the heating furnace is transferred by a roller table or the like, and is sequentially rolled through the rolling rolls. As shown in the figure, the spray nozzles 3 are arranged on both sides of the rolling mill 2 and 2 'facing the rolling mill with the pass of the steel material 1 interposed therebetween from the steel material outlet side of the rolling mill. Note that only one spray nozzle is shown in the figure. In the example of the drawing, the spraying direction of the spray nozzle 3 is directed in the direction opposite to the rolling direction, and the range of the spraying is the undeformed portion of the heated steel material slightly before the deformation starting position of the heated steel material during rolling. Coolant sprayed in water or water and water
It is a mixed fluid of air . The spray that has been sprayed reaches the undeformed part before the deformation start position of the heated steel material, so that the surface scale is cooled before the deformation starts, and due to the cooling effect, the difference in the shrinkage rate between the steel material and the surface scale causes some Is peeled off, and the remaining part is directly subjected to deformation processing by the rolling rolls 2 and 2 ′. Here, utilizing the difference in the deformation mode between the scale and the steel material due to cooling, the peeling of the scale is promoted, and at the same time, the peeling scale is removed by spraying. With respect to the above-described arrangement of the spray nozzle, the spray nozzle 3 is arranged on the steel material inlet side of the rolling mill, and the spray is sprayed from the undeformed portion of the heated steel material to the portion until the deformation is completed. the direction is arranged toward the traveling direction of the rolling, water if more spray nozzles
Alternatively, a configuration may be employed in which a mixed fluid of water and air is jetted. In the figure, reference numeral 4 denotes a peeled scale.
It is extremely effective to apply such descaling in a first pass rolling mill or a rolling mill up to a plurality of passes for a steel material heated in a heating furnace.

FIG. 2 shows an example in which the present invention is applied to a rolling mill having a plurality of passes. In this example, the first stand is a horizontal rolling mill 10 and the second stand is a vertical rolling mill 11, which is arranged in tandem. Hydraulic water tank 12 and compressed air tank 13
Is connected to the spray nozzle 3 via the mixing valve 14. The spray nozzle 3 is disposed so as to be in the direction opposite to the rolling direction from the gaps on both sides of the path of the opposing rolls 2 and 2 ', and the spray is sprayed from the undeformed portion of the steel material to the portion where the deformation is completed. You.

[0007]

[Test Example] As shown in FIG. 2, a descaler was installed on the stand 1 and the stand 2, and the descaler was not installed on the subsequent stand. Steel) is 110mm
Rolling of angle → 13φ was performed. Conditions for descaling Water pressure: 2.7 kgf / cm ² , Compressed air pressure: 3.7 kgf / cm ² Water volume 7 (l / min), two-phase mixed spray from nozzle The descaling is performed with the injection descaler, and the SU
For S304 and SUP6, 110mm square → 5.5φ, 13φ
3 and FIG. 4 show the results obtained by rolling under the same conditions as those described above, respectively, in comparison with those obtained by carrying out the present invention. 3 and 4 show the surface roughness of each steel wire in ten-point average roughness in the unit length of the steel wire, as shown in FIGS. 3 and 4. It can be seen that the level of surface roughness is improved.

[0008] In the above-mentioned rolling, the service life of the rolling roll is extended by 1.2 to 1.6 times.

If the descaling is performed according to the present invention, the pressure of the water to be sprayed is extremely low as compared with the conventional one, the equipment is simple, the initial cost is low, and the restriction on the mounting position is small. And as described above, it is easy to attach to each rolling mill, and the descaling performance is remarkably improved.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a descaling unit of FIG. 2;

FIG. 2 shows an embodiment of the present invention.

FIG. 3 is a graph illustrating a ten-point average roughness of a rolled product surface obtained by performing the descaling of the present invention and a rolled product surface obtained by performing the conventional descaling for steel type SUS306.

FIG. 4 is a comparison graph of ten-point average roughness of a rolled product surface obtained by performing the descaling of the present invention and a rolled product surface obtained by performing the conventional descaling for steel type SUP6.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heated steel material 2, 2 'Roll roll 3 Spray nozzle 4 Peeling scale 10 Horizontal type rolling mill 11 Vertical type rolling mill 12 Hydraulic water tank 13 Compressed air tank 14 Mixing valve

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B21B 45/08 B21B 1/26

Claims (1)

(57) [Claims] 1. A horizontal rolling mill and a vertical rolling mill are alternately used.
A method for descaling a hot-rolled steel material to be tandem-rolled, wherein the first-pass rolling mill in the rough rolling stage or the rolling mill from the rolling mill to a plurality of pass rolling mills is slightly deflected from a deformation starting position of the steel material during rolling. The part of the opposing roll extends from the undeformed portion of the steel
Water is sprayed from the spray nozzles located in the gaps on both sides of the steel material path.
Alternatively, a descaling method of a hot-rolled steel material, wherein a mixed fluid of water and air is sprayed onto the steel material in a spraying direction from a rolling direction or a direction opposite to the rolling direction.