JP2019076924A - Hot scarfer, and scarfing method of slab - Google Patents

Abstract

To suppress generation of unevenness caused by adhesion prevention of molten slag onto a unit or by generation prevention of insufficient preheating, by reducing dispersion in a width direction of preheating by a hot scarfer.SOLUTION: A hot scarfer 1 in which a plurality of insert nozzles 3 including a plurality of fuel gas injection holes 32 around a center hole 31 which is an oxygen injection port are arranged in a width direction, has a constitution in which the insert nozzles are fitted with a fitting angle in the range of a prescribed angle of ±5 degrees at least alternately.SELECTED DRAWING: Figure 8

Description

  TECHNICAL FIELD The present invention relates to a hot scarver and a method of lathing a slab.

  As described in Patent Document 1, it is known to use a hot scarver to erase a slab having a surface defect. By uniforming the cross-cutting in the slab width direction by the hot scarver to avoid non-uniform scarfing, it is possible to avoid the occurrence of so-called tiger cutting. Avoiding the occurrence of tiger cutting means reducing the number of slabs that require a hand scarf process, and reducing the furnace unit rate by improving the rate of Hot Slab furnace charging (HCR). Important for.

  It is very important to ensure the uniformity in the width direction of the preheating to be performed before the machining in order to secure the uniformity in the width direction. Here, the scarcer processing will be briefly described. After transporting the slab into the scarf, as shown in FIG. 13, the unit is brought close to the slab and the surface of the slab is preheated to form a molten pool by utilizing an insert nozzle incorporated in the unit. The insert nozzle mainly plays a role of slab preheating. Thereafter, while reducing the combustion load of the insert nozzle, the slot oxygen pressure is increased to cause the molten pool to collide with the slot oxygen, and the movement of the slab is started in a state where the oxidation reaction has occurred. Thus, by moving the oxidation reaction in the molten pool, the oxidation reaction is continuously caused on the slab surface to polish the slab surface.

Patent 2606473

  As described above, since the preheating forms the first starting point of the etching, the uniform preheating in the width direction is very important for the uniform removal in the width direction. For example, if the preheating is uneven in the width direction and the machining starts, the less preheated portions become unerased and scraping occurs. If the preheating time is taken long as a countermeasure, the difference in the depth of the molten pool between the strong preheating part and the weak part occurs, and this difference in the depth of lathe cutting is dragged during lathe removal, and the lathe thickness is uneven in the width direction It becomes. In addition, the gas jets of the slot oxygen collide with the deep molten pool to jump up the molten slag in a large amount, and adhere to the unit, causing the preheating abnormality and the ablation abnormality. Thus, uniform preheating in the width direction is very important in scarper operation.

  The present invention is an invention made in such a background, and the subject of the present invention is to prevent adhesion of molten slag to the unit and to prevent the insufficient preheating portion by reducing the variation in the width direction of the preheating by the hot scarver. It is to suppress the occurrence of tiger pruning by preventing the occurrence.

  In order to solve the above problems, a hot scarver is provided in which a plurality of insert nozzles provided with a plurality of fuel gas injection holes are arranged in the width direction around a central hole serving as an oxygen injection port. Every other time, the hot scuffer is characterized in that the mounting angle is within a predetermined range of ± 5 degrees.

  Further, it is preferable that all the insert nozzles be attached within a predetermined angle of ± 5 degrees.

  Further, it is preferable that the number of fuel gas injection holes is four for one insert nozzle, and the fuel gas injection holes are arranged in two rows in parallel with the direction in which the insert nozzles are arranged. .

  In addition, the diameter of the fuel gas injection hole of the insert nozzle is 10 mm or less, and the attachment angle of one of the insert nozzles is attached in a state where the range of the predetermined angle ± 5 degrees is exceeded. Preferably, the insert nozzles located on both sides of are mounted at an attachment angle within a predetermined range of ± 5 degrees.

  In addition, a method of removing a slab by using a hot scarver in which a plurality of insert nozzles including a plurality of fuel gas injection holes are disposed in the width direction around a central hole serving as an oxygen injection port, the insert A method of ablation machining a slab characterized in that every other nozzle is abraded using a hot scafer attached at an attachment angle within a predetermined range of ± 5 degrees.

  Further, it is preferable that a hot scarver used in the method of lava-cutting a slab has a configuration in which all insert nozzles are attached within a predetermined angle of ± 5 degrees.

  In addition, there are four holes for fuel gas injection per one insert nozzle, and the holes for fuel gas injection are arranged using two lines in parallel with the direction in which the insert nozzles are arranged. It is preferable to polish.

  In addition, the diameter of the fuel gas injection hole of the insert nozzle is 10 mm or less, and the attachment angle of one of the insert nozzles is attached in a state where the range of the predetermined angle ± 5 degrees is exceeded. Preferably, the insert nozzles located on both sides of the are etched using a hot scarfer attached at a mounting angle within a predetermined range of ± 5 degrees.

  By using the present invention, it is possible to suppress the occurrence of tiger cutting due to the prevention of adhesion of molten slag to the unit and the prevention of the generation of the insufficient preheating portion by reducing the variation in the width direction of the preheating by the hot scarver.

It is a schematic diagram showing the cross section and front of a unit of an embodiment. It is a figure showing the relationship between the attachment angle of an insert nozzle, and the analysis result of the flow ratio of propane gas. It is a schematic diagram of a preheat simulator. It is a figure showing the measurement result of a temperature rising rate at the time of making an insert nozzle into A arrangement | positioning and B arrangement | positioning which are shown in FIG. It is a figure showing the result of having calculated the transition of the temperature of the slab surface based on the result represented by FIG. It is a figure showing the example of an insert nozzle. It is a schematic diagram of a unit which attached an insert nozzle in the state of improvement level 1. It is a schematic diagram of the unit which attached the insert nozzle in the state of improvement level 2. FIG. It is a schematic diagram of the unit which attached the insert nozzle in the random state like conventional. It is a figure showing the outline of the measuring method of a molten pool production width ratio. It is a figure showing the relationship between the attachment angle of an insert nozzle, the time from a pre-heating start, and a molten pool production | generation width ratio. It is a figure showing the relationship between the attachment angle of an insert nozzle, and the number ratio of a tiger pruning slab. It is a figure showing the state which has preheated the slab and the state which has etched the slab by the unit of the hot scarver.

  Hereinafter, embodiments of the invention will be described. As understood from what is shown in FIG. 1, in the hot scarver 1 in the present embodiment, the insert nozzle 3 having a plurality of fuel gas injection holes 32 is attached around the center hole 31 serving as an oxygen injection port. ing. Also, a plurality of the insert nozzles 3 are arranged in the width direction of the hot scarver 1. Furthermore, a plurality of the insert nozzles 3 arranged side by side are attached so that the attachment angle thereof is within a predetermined range of ± 5 degrees every other one. For this reason, by reducing the variation in the width direction of the preheating by the hot scarver 1, it becomes possible to suppress the occurrence of the tiger cutting due to the adhesion prevention of the molten slag to the unit 2 and the generation prevention of the insufficient preheating portion. The attachment angle means the angle in the circumferential direction of the nozzle when the hole 32 is viewed from the side to which the fuel gas is injected, as understood from FIG. 1. It can be changed by the screwing amount. For example, there is a difference of approximately 45 degrees between the mounting angle represented as A in FIG. 1 and the mounting angle represented as B.

  The hot scarver 1 has a plurality of units 2 arranged side by side, but the upper hot scarver 1 shown in FIG. 1 shows the attachment state of the insert nozzle 3 to the unit 2 and the supply flow of fuel gas and oxygen to the insert nozzle 3. An example will be described. Here, the fuel is described as propane gas. The insert nozzle 3 is installed by being screwed into the insert nozzle mounting hole 21 of the upper block. A plurality of insert nozzle mounting holes 21 are provided so as to line up in the width direction of the hot scarver 1. One insert nozzle 3 is screwed into each of the insert nozzle mounting holes 21. Oxygen can be supplied to the outside of the hot scarver 1 from the slot gap 22, the holes 23 arranged in the width direction of the upper block, and the central hole 31 of the insert nozzle 3. The slot gap 22 is formed by the gap between the upper block and the lower block.

  Propane gas is injected through a plurality of, for example, four holes 32 arranged around the central hole 31 of the insert nozzle 3 in addition to the holes 24 arranged in the lower block in the width direction. At this time, the propane gas injected through the plurality of holes 32 passes through the flow passage opened in parallel to the insert nozzle 3, and the inner periphery of the insert nozzle mounting hole 21 and the outer periphery of the longitudinal center of the insert nozzle 3 The pressure is supplied to the pressure equalizing chamber 25 which is a space formed by the narrow diameter portion, and the pressure is equalized.

  The insert nozzle 3 is screwed into the insert nozzle mounting hole 21 of the lower block and installed since it is upside down to the case of the upper hot scarver 1 in the case of the lower hot scarver 1 which cuts the lower surface of the slab 5. Ru. Also, oxygen can be supplied from the slot oxygen, the holes 23 arranged in the width direction of the lower block, and the central hole 31 of the insert nozzle 3. In addition, propane gas is injected through holes 24 arranged in the width direction in the upper block and a plurality of, for example, four holes 32 arranged around the center hole 31 of the insert nozzle 3. The fuel gas injection holes 32 are provided on a circle centered on the central hole 31. Hereinafter, the upper hot scarver 1 will be described as an example.

  By the way, the flow path 26 of the fuel gas connected to the pressure equalizing chamber 25 is provided so that the fuel gas is introduced to the pressure equalizing chamber 25 from the oblique direction. Therefore, the inventor has found that when the insert nozzle 3 is attached as shown in A of FIG. 1 and A of FIG. 2, the fuel gas flow path 26 and the four holes 32 of the four holes 32 surrounding the central hole 31 of the insert nozzle 3. Since one hole 32 is connected in a straight line, it is considered that there is a high possibility that the fuel gas is preferentially ejected from this hole 32.

  On the other hand, when the insert nozzle 3 is mounted as shown in FIGS. 1B and 2B, the fuel gas flow path 26 is in line with all the four holes 32 surrounding the center hole 31 of the insert nozzle 3. It was considered that the header effect of the pressure equalizing chamber 25 was sufficiently obtained and the possibility that the propane gas would be injected uniformly from the four holes 32 is high because they do not line up.

  Figure 2 shows the results of flow analysis. When attached as shown in A of FIG. 2, it is understood that, as understood from C of FIG. 2, about 40% of propane gas is preferentially extracted from the holes 32 aligned with the flow path of propane gas. It spouted. Further, in the case where the propane gas was attached as shown in FIG. 2B, propane gas was ejected almost uniformly from the four holes 32, as understood from the fact shown in D of FIG.

  The influence of the mounting direction of the insert nozzle 3 on the preheating was quantified by the preheating simulator 4 as shown in FIG. In the preheating simulator 4, the unit 2 of the hot scarver 1 is installed upward, oxygen and propane gas are set at an arbitrary pressure and burned, and the steel plate attached to the carriage is slid out of the unit 2 The preheated flame was heated, and the temperature rise was measured by a thermoviewer fixed to the top of the steel plate.

  The measurement results of the temperature rising rate in the case where the mounting direction of the insert nozzle 3 is adjusted to A in FIG. 2 and to B in FIG. 2 are shown in FIG. It was found that the temperature rising rate was faster in the case of FIG. 2A than in the case of FIG. 2B.

  The heat flux of the heat input to the steel plate is estimated from the temperature rising rate, and the calculated heat flux of the slab 5 is applied to the surface of the slab 5 at 700 ° C. The calculation results of the transition of the surface temperature of the slab 5 are shown in FIG. For example, 11 seconds after the start of preheating, the level adjusted to A was 1370 ° C. or higher, which is the melting point of wustite, and the level adjusted to B in the previous period was 1370 ° C. or lower. From this, depending on the combination of the mounting directions of the insert nozzles 3 lined in the width direction of the hot scarver 1, at the end of the preheating, the mixture of the intense melting portion and the unmelted portion occurs in the width direction It can be seen that preheating variations can occur. In such a state, there is a high possibility that the slag of the partially produced deep molten pool may scatter and adhere to the unit 2. In addition, the possibility of scraping is increased by starting the metal removal while the unmelted part remains.

  On the other hand, by arranging the mounting angles of all the insert nozzles 3 to be the same, making the preheating ability of each insert nozzle 3 uniform and preventing the occurrence of preheating unevenness in the width direction can prevent the occurrence of tiger mowing . For example, as shown in FIG. 6, when there are four holes 32 of propane gas arranged at equal intervals in the circumferential direction, as shown in FIG. It is preferable to arrange in line with the letter. That is, it is preferable to arrange the holes 32 for fuel gas injection so as to be arranged in two rows in parallel with the direction in which the insert nozzles 3 are arranged. With this arrangement, propane gas can be ejected uniformly from the four holes 32. However, this arrangement is not essential, and the propane gas holes 32 may be in the shape of a cross. In this case, the holes 32 for fuel gas injection are arranged in three rows in parallel with the direction in which the insert nozzles 3 are arranged. When the holes 32 of the propane gas are aligned in a straight line, the amount of propane gas ejected from the four holes 32 is slightly nonuniform, but in comparison with those in which the holes 32 of the propane gas are randomly arranged, It is possible to reduce the occurrence of preheating unevenness in the width direction. Moreover, even if it arranges by these intermediate arrangements, generation | occurrence | production of the pre-heat nonuniformity generation | occurrence | production of the width direction can be prevented, and tiger mowing generation can be prevented.

  When the diameter of the insert nozzle 3 is as small as 10 mm or less, as shown in FIG. 8, every other insert nozzle 3 disposed in the width direction of the upper (or lower) block is attached at the same attachment angle It has been found that if the mounting angle of the insert nozzle 3 located therebetween is different from the mounting angle of the insert nozzle 3 located on both sides, it is possible to prevent the occurrence of the tiger pruning. This is because, since the diameter of the insert nozzle 3 is small, the intensely melted portion and the unmelted portion are blunted, and it is possible to absorb preheating unevenness in the width direction. For example, when the diameter of the insert nozzle 3 is 10 mm or less, even if the insert nozzle 3 is attached such that two attachment angles occur alternately, it is possible to absorb preheating unevenness in the width direction. Here, the same mounting angle is within ± 5 °, preferably ± 3 °.

  Next, an embodiment will be described. The arrangement of the mounting angle of the insert nozzle 3 was changed by the hot scarver 1 of the actual machine to evaluate the uniformity in the width direction of the preheating capacity. The installation of the insert nozzle 3 is the improvement level 1 (FIG. 7) in which all the insert nozzles 3 are attached at the same angle, and the diameter of the fuel gas injection hole 32 of the insert nozzle 3 is 10 mm or less. The improvement level 2 (FIG. 8), which is disposed at the same angle every other one in the width direction of the scarfer 1, and the random disposition currently performed (FIG. 9).

  In addition, in order to evaluate the uniformity in the width direction of the preheating capability, as is understood from that shown in FIG. The molten pool formation width ratio was quantified. The molten pool formation width ratio is a value obtained by dividing the total width value of the molten pool generated at an arbitrary timing after the start of the preheating, by the slab width, as understood from FIG. In addition, low carbon aluminum killed steel with a width of 1540 mm and a surface temperature of 740 to 760 ° C. was used in the test.

  Figure 11 shows the transition of representative molten pool formation width ratio at each level. Improvement level 1 and improvement level 2 increase the molten pool formation width ratio from 0% to 100% rapidly in a short time, compared with the current distribution of molten pool formation width ratio of random arrangement gradually over time It could be confirmed that This indicates that the uniformity of the preheating ability in the width direction is high.

  The actual machine test was conducted for about one week at each level, and the results of surveying the ratio of the number of slabs in which tiger pruning occurred are shown in FIG. It was confirmed that the improvement level 1 and the improvement level 2 can reduce the ratio of scraped slabs to about 1/3 compared to the current random arrangement.

  As understood from what has been described so far, the uniformity of the preheating ability in the width direction can be obtained by using the hot scarfers 1 arranged so that the mounting angles of all the insert nozzles 3 become substantially the same. The number of slabs that can be cut can be significantly reduced, and cost reductions can be achieved by preventing an increase in the number of processes for hand scarfs, and the basic unit cost reduction can also be realized by improving the HCR rate.

  In addition, if the diameter of the fuel gas injection hole 32 of the insert nozzle 3 is 10 mm or less and the attachment angle is made to be similar every other one, the insert nozzle 3 positioned between them Even if the mounting angle of the insert nozzle 3 is different from the mounting angle of the insert nozzle 3 located on both sides of the insert nozzle 3, the uniformity of the preheating ability in the width direction is improved, and the number of It has been confirmed that cost reduction can be achieved by preventing an increase in the number of processes of the scarf, and reduction in heating furnace unit cost can also be realized by improving the HCR rate.

  In the hot scarver 1, if the insert nozzles 3 are attached at least every other attachment angle within a predetermined range of ± 5 degrees, the variation in the preheating width direction is reduced However, if all the insert nozzles 3 are attached within a predetermined angle of ± 5 degrees, the variation in preheating can be further reduced.

  By providing four holes 32 for fuel gas injection with respect to 31 insert nozzles, and arranging the holes 32 for fuel gas injection in two rows parallel to the direction in which the insert nozzles 3 are arranged, Variations in preheating can be further reduced.

  If the diameter of the fuel gas injection hole 32 of the insert nozzle 3 is 10 mm or less, even if the attachment angle of one of the insert nozzles 3 is attached in a state where the range of the predetermined angle ± 5 degrees is exceeded, If both of the insert nozzles 3 located on both sides of the insert nozzle 3 are attached within the range of the predetermined angle ± 5 degrees, the variation in preheating can be effectively reduced.

  As mentioned above, although it demonstrated centering on two embodiment, this invention is not limited to the said embodiment, It is possible to set it as various aspects. For example, the attachment angle of the insert nozzle located between the insert nozzles attached at a predetermined angle of ± 5 degrees may be random.

  The number of fuel gas injection holes may not be four, and may be two, three, five or more.

Reference Signs List 1 hot scarver 3 insert nozzle 5 slab 31 central hole 32 hole

Claims (8)

A hot scarver in which a plurality of insert nozzles provided with a plurality of fuel gas injection holes are arranged in the width direction around a central hole serving as an oxygen injection port,
A hot-speaker characterized in that at least every other insert nozzle is attached at an attachment angle within a predetermined range of ± 5 degrees.   The hot scarver according to claim 1, wherein all the insert nozzles are attached within a predetermined angle ± 5 degrees.   The number of fuel gas injection holes is four for one insert nozzle, and the fuel gas injection holes are arranged in two rows parallel to the direction in which the insert nozzles are arranged. Hot scarver described in.   The diameter of the fuel gas injection hole of the insert nozzle is 10 mm or less, and the attachment angle of one of the insert nozzles is attached outside the range of a predetermined angle ± 5 degrees, both sides of the insert nozzle The hot scarver according to claim 1, characterized in that the insert nozzle located in (1) is mounted within a range of a mounting angle of ± 5 degrees. A method of removing a slab using a hot scarver in which a plurality of insert nozzles having a plurality of fuel gas injection holes are disposed in the width direction around a central hole serving as an oxygen injection port.
A method according to any one of the preceding claims, characterized in that the insert nozzles are etched using a hot scaper attached at an interval of at least one other within a predetermined range of ± 5 degrees.   6. The method according to claim 5, wherein the insert is removed by using a hot scarver in which all the insert nozzles are attached within a predetermined range of ± 5 degrees.   There are four holes for fuel gas injection to one insert nozzle, and the holes for fuel gas injection are etched using hot scarfers arranged in two rows parallel to the direction in which the insert nozzles are arranged. The method according to claim 6, characterized in that:   The diameter of the fuel gas injection hole of the insert nozzle is 10 mm or less, and the attachment angle of one of the insert nozzles is attached outside the range of a predetermined angle ± 5 degrees, both sides of the insert nozzle The method according to claim 5, characterized in that the insert nozzle located in the step (6) is etched using a hot scarver mounted at a mounting angle within a predetermined range of ± 5 degrees.