JP2007002313A - Method for charging metal pieces into heating furnace for hot-rolling - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for charging metal pieces with which in a heating furnace for a hot-rolling line, even in the case of feeding the metal pieces having different lengths at different timing, the saving of fuel consumed in the heating furnace is obtained and also, the generations of deteriorated quality and such state as to drop the producing efficiency can be avoided. <P>SOLUTION: In two metal pieces 8 having different timings fed into the hot-rolling line 100, one piece earlier supplied in two metal pieces whose total length is shorter than the longest metal piece charged into the heating furnace 10 for the hot-rolling line, is waited for a time while keeping the temperature in a temperature holding pit 103, and at the time point when the one piece for later supplying is supplied, the two metal pieces are lined to two pieces in the longitudinal direction and charged into the heating furnace for the hot-rolling line. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for charging metal pieces into a heating furnace in hot rolling.

Metal plates (meaning including metal strips), especially thin steel plates typified by steel strips, are cast and cast into slab-like metal pieces, and then hot rolled and cold rolled. In some cases, it may be manufactured or further plated.
By the way, the strip steel is a thin steel plate with a thickness of 1.2 mm or more and a width of 600 mm or more, as specified in JIS G 3193, etc., which is wider than a flat steel (specifically, a width of 500 mm). Super) steel material. In addition, there are areas where the steel strip wraps with the steel plate and part of the product thickness and product width, but the difference between the steel strip and the steel plate is that the former is wound after rolling, while the latter is not wound. There is.

  Hot rolling refers to extending a thin piece by heating a metal piece to several hundred to several hundreds of degrees Celsius, extracting it on a hot rolling line, and rotating the roll while pinching with a pair of rolls. . FIG. 4 shows an example of a hot rolling line 100 that has been conventionally used. The metal piece 8 having a thickness of 150 to 300 mm heated to several hundred to several hundreds of degrees Celsius by the heating furnace 10 is extended to a thickness of 20 to 60 mm by the rough rolling mill 12, and further thinned by the finish rolling mill 18. Rolled to a thickness of 0.9-25mm.

  In the case of the hot rolling line 100 shown in FIG. 4, the rough rolling mill 12 has three groups of R1, R2, and R3, but the number of bases is not necessarily limited thereto. In addition to one or two, the most common one is four, and the one with a large number is up to six. In the case of the most general four units, a type called 3/4 continuous (three quarters) in which a part of the four units (one in many cases) is reciprocally rolled, and the remaining rolling mill performs one-way rolling. There are many. However, three of the four groups are not limited to the one-way type, and for example, as shown in FIG. Some have a width press 9 installed immediately upstream of the roughing mill 12.

In the case of the finish rolling mill 18 shown in FIG. 4, there are seven groups F1 to F7, but the number is not necessarily limited thereto. Generally, it is 6-7 groups.
Although there are differences in these various radixes, the roughing mill 12 generally performs rough rolling 6 times or 7 times in total by reciprocating rolling or unidirectional rolling, or both, and the metal piece 8 after rough rolling is obtained. Then, it is supplied to the finishing mill 18. Rolling a plurality of times such as 6 times or 7 times is also referred to as rolling with 6 passes or 7 passes.

The finishing mill 18 takes the form of a hot tandem finishing mill that simultaneously rolls a high-temperature metal piece 8 of several hundred to several hundreds of degrees Celsius with a plurality of rolling mills, but is simply referred to as a “finishing mill” for short. Often done. 19 is a work roll.
By the way, in the hot rolling line 100, except for between the stands of the finish rolling mill 18, a large number (100 or more) of table rollers (not shown) are installed between the other rolling mills (stands). 8 is conveyed.

  By the way, when extracted from the heating furnace 10, an oxide layer (hereinafter referred to as scale) is formed on the front and back surfaces of the high-temperature metal piece 8 heated to several hundred to several hundreds of degrees Celsius as described above. ing. In addition, since the metal piece 8 is exposed to the atmosphere at a high temperature even in the process of being rolled and thinned and being cooled by heat radiation, new scales are generated on the front and back surfaces of the metal piece 8. For this reason, a descaling device that removes scale by spraying high and low pressure water inside and outside 10 to 30 MPa on the front and back surfaces of the metal piece 8 at the inlet side of each rolling mill in the rough rolling mill 12. 16 is installed and the scale is removed.

In FIG. 4, reference numeral 14 denotes a crop shear, which cuts and removes the crop at the front and rear ends of the metal piece 8 (the irregular planar shape portion at the front and rear ends of the metal piece 8) before finish rolling, It is shaped into a substantially rectangular planar shape that is easy to bite.
50 is a control device, 70 is a process computer, and 90 is a business computer.
The upper and lower roll gaps of each of the roughing mill 12 and the finishing rolling mill 18 have data as the data in the process computer 70, and the planned (desired) thickness of the metal piece 8 on the outlet side of each rolling mill. The result of calculating the elongation of the rolling mill housing due to the rolling reaction force (rolling load) is calculated in the process computer 70 so as to be added, and set and adjusted before the tip of each metal piece 8 is bitten. . The rotational speed of each roll is also calculated in the process computer 70 and set and adjusted before the tip of each metal piece 8 is bitten.

  Further, in many cases, in the first rolling mill F1 of the finish rolling mill 18, the rolling interval in F1 from when the leading end of the preceding metal piece 8 comes off until the leading end of the following metal piece 8 bites. The time when each metal piece 8 should be extracted from the heating furnace 10 is calculated in advance in the process computer 70 with the goal of adjusting the value to a desired value. Mil pacing control is performed to extract each metal piece 8 from 10.

  15 is a finish entry side thermometer, which measures the temperature of the metal piece 8 before finish rolling, and each piece of metal piece 8 when each piece of metal piece 8 bites into the finishing mill 18. The role of starting the calculation and the temperature data for performing various settings (setup) for rolling the roll based on the result of determining the set value by calculation in the process computer 70 It also serves to provide the control device 50 and the process computer 70.

  Reference numeral 21 denotes a finisher-side thermometer, which serves to provide temperature data to the control device 50 and the process computer 70. Reference numeral 22 denotes a finishing delivery thickness gauge, which plays a role of providing thickness data to the control device 50 and the process computer 70. Reference numeral 23 denotes a table roller group called a run-out table in a cooling zone for cooling the metal piece 8 after finish rolling with water. A coiler 24 winds up the cooled metal piece 8. Reference numeral 25 denotes a coiler inlet side thermometer, which serves to provide temperature data to the control device 50 and the process computer 70. Although not particularly illustrated, a slab-like metal piece storage area called a slab yard is provided on the entrance side of the heating furnace 10.

  In such a hot rolling line 100, one piece of metal 8 is rolled and then the next piece of metal 8 is rolled, and the rolling in the finishing mill 18 is performed. One intermittent finish rolling may be particularly referred to as batch rolling. When batch-rolling the metal pieces 8 in the finish rolling mill 18, the tips thereof are sequentially engaged with F1 to F2, F3,... Final rolling mill (F6 or F7). After biting into the final rolling mill, all the rolling mills are rolling the metal piece 8 simultaneously (tandem rolling). Thereafter, after rolling progresses, the tail ends are sequentially withdrawn from F1 to F2, F3,..., The final rolling mill (F6 or F7).

  By the way, in hot rolling, since the load of the heating furnace 10 increases as the temperature of the metal piece 8 at the time of charging into the heating furnace 10 increases, it is used for the manufacture of almost all the metal pieces 8 today. 5, after casting the slab-like metal piece 8 by the continuous casting line 28, the metal piece 8 that is still at a high temperature inside and outside 500 to 1200 ° C. is cast in as short a time as possible after casting. DHCR (Direct Hot Charge Rolling), which attempts to save the fuel consumed in the heating furnace 10 by being charged in the heating furnace 10, has been widely performed. The metal piece 8 to be subjected to DHCR is not substantially stored in the slab yard, and is charged into the heating furnace 10 as soon as possible after casting. Substantially, the time temporarily placed in the slab yard is, for example, within 4 hours, or the temperature of the metal piece at the time of charging into the heating furnace 10 regardless of the time temporarily placed, for example, There are various definitions depending on the company, such as 700 ° C or higher, but there are also cases where it is DHCR even if it is stored in the slab yard for a short time. In addition, DR (Direct Rolling) in which the cast metal piece 8 is directly rolled in the hot rolling line 100 without passing through the heating furnace 10 may be performed. For those who are.

  Patent Document 1 discloses a heat insulation pit for temporarily placing a metal piece 8 being transported at a high temperature after being cast in a continuous casting line 28 to be inserted into a heating furnace 10 of a hot rolling line 100. In addition, it is described that one of a plurality of heating furnaces 10 of the hot rolling line 100 provided as a transfer route is used as a dedicated heating furnace for DHCR. When the high-temperature metal piece 8 does not enter the heating furnace, the metal piece 8 is inserted into a high-temperature dedicated heat insulation pit adjacent to the heating furnace 10 to suppress the temperature reduction of the metal piece 8 as much as possible. On the other hand, it is made to wait for a while until the heating furnace 10 has a space.

  On the other hand, the length of the metal piece 8 varies from 4 to 13 m depending on the company, depending on the company, and there are various lengths. The heating furnace 10 can be installed even with the longest metal piece 8 handled at the factory of the company. When the short metal piece 8 comes in, the empty space in the heating furnace 10 becomes large, and the cover ratio of the heating furnace 10 (the piece of metal in the heating furnace that occupies the heating floor area) 8) The total surface area (the total ratio of the front and back sides)) is reduced, and as a result of wasteful consumption of fuel, the production cost may increase due to the deterioration of the basic unit.

In order to prevent this, Patent Document 2 describes that two metal pieces 8 are long as long as the total length is equal to or less than the length of the longest metal piece 8 entering the heating furnace 10 of the hot rolling line 100. It is described that two sheets are arranged in the vertical direction and charged into the heating furnace 10 of the hot rolling line 100.
JP 2004-084030 A JP 2002-309316 A

  However, two short metal pieces 8 are not always sent to the hot rolling line 100 (in many cases, a slab yard not shown) close to each other in timing, For example, even if the short metal piece 8 is fed to the hot rolling line 100 at a time interval of 24 hours, for example, the temperature of the metal piece 8 that has arrived first decreases to a temperature close to room temperature. In addition, since it is no longer a DHCR, it is impossible to save the fuel consumed in the heating furnace 10, which is the purpose.

  When the temperature of the metal piece 8 arriving first and the temperature of the metal piece 8 arriving later are different from each other by 500 ° C. or more, the two metal pieces 8 are When the sheets are placed side by side and placed in a heating furnace, it appears as a difference in the baking temperature between 50 and 100 ° C., and the subsequent hot rolling causes the low-temperature metal piece 8 to be rolled too much at a low temperature. Failure occurs, or operation of the hot rolling line 100 must be temporarily stopped until the lower temperature metal piece 8 reaches the normal heating target temperature, leading to a situation in which the production efficiency is lowered. Problems arise.

  The present invention has been made to solve the problems of the prior art as described above. That is, the present invention is two pieces of metal having different timings sent to the hot rolling line, and the total length is equal to or less than the length of the longest piece of metal entering the heating furnace of the hot rolling line. Of the two metal pieces, the first piece supplied first is kept warm while being kept warm. When one piece supplied later is supplied, the two pieces of metal are A method of charging metal pieces into a heating furnace in hot rolling, wherein two sheets are arranged in the vertical direction and charged into a heating furnace of a hot rolling line.

  According to the present invention, even if the short metal piece 8 is fed to the hot rolling line 100 with a long time interval of 24 hours, for example, the temperature of the metal piece 8 that has arrived first, Since the temperature of the metal piece 8 arriving later can be brought close to a considerable degree, the fuel consumed in the heating furnace 10 can be saved, which is the purpose of DHCR, and the occurrence of poor quality. It is possible to avoid the occurrence of a situation where the production efficiency is lowered.

  In the present invention, two metal pieces 8 having different timings fed to the hot rolling line 100, the total length of which is the longest metal piece 8 entering the heating furnace 10 of the hot rolling line 100. Of the two metal pieces 8 that are less than or equal to the length, one piece of metal supplied earlier is temporarily kept warm while one piece of metal supplied later is supplied. Two pieces 8 are arranged in the length direction and charged into the heating furnace 10 of the hot rolling line 100.

  Here, the difference in width between the two metal pieces is preferably within 200 mm. If the metal piece 8 has a width difference of more than 200 mm, even if two pieces are arranged side by side in the length direction and inserted into the heating furnace 10, it can be formed between the adjacent metal pieces 8 in the heating furnace 10. This is because the gap becomes too large and the fuel saving effect may be diminished. Of course, the present invention is not limited to this.

FIG. 1 shows a hot rolling line 100 shown in FIG. 4 in which a high-temperature metal piece 8 is temporarily held in a dedicated heat insulation pit 103 and two metal pieces 8 whose width difference is close to within 200 mm are arranged and heated. 3 is a schematic view of how the furnace 10 is charged.
Of the two metal pieces 8, one of the metal pieces 8 that has been sent first receives attribute data such as length and width from the business computer 90 as a command value or from a sensor (not shown) as a result value. It is sent via the control device 50, or temporarily stored as information in the process computer 70 by any method, and then loaded into the heat retaining pit 103 using the traverse cart 101 and the loader 102, Wait. Until one of the ones supplied later arrives, one of the ones sent earlier is the top of the mountain where another piece of metal 8 is stacked in the heat insulation pit 103 or the same heat insulation pit. Although it is desirable to temporarily place it in a position where it can be easily taken out from the heat retaining pit 103 when the timing for charging into the heating furnace 10 finally arrives, such as an empty space in 103, it is not limited thereto.

  Attribute data similar to the one supplied earlier as one of the later supplied arrives at the entrance of the heating furnace 10 or the slab yard of the hot rolling line 100. Is checked in the process computer 70 with the attribute data of the previously supplied one, and if the total width difference and length meet the conditions, a temporary standby is performed by a command from the control device 50. The metal pieces 8 that have been removed are extracted from the heat insulation pit 103, and are placed in the heating furnace 10 in a line in the length direction.

FIG. 2 is an example of the heat retaining effect when the metal piece 8 is placed in the dedicated heat retaining pit 103. It can be seen that the temperature when the metal piece 8 is charged into the heating furnace 10 is higher when the metal piece 8 is temporarily placed in the heat retaining pit 103 than when the metal piece 8 is temporarily placed in the outdoor metal piece place.
FIG. 3 is a diagram showing how the two pieces of metal 8 are extracted from the heating furnace 10 and then conveyed toward the roughing mill 12 of the hot rolling line 100. The piece 8 is once conveyed in the reverse direction, and the metal piece conveyed in the direction opposite to the conveyance direction A is conveyed in the direction opposite to the inside and outside of 3 to 15 m, and then conveyed in the conveyance direction A. The two metal pieces are transported while being close to each other, and the trouble of continuing to bite into the roughing mill 12 is prevented.

It is a schematic diagram which shows embodiment of this invention. It is a figure which shows the example of the heat retention effect at the time of putting a metal piece in a dedicated heat retention pit. It is a figure shown about how to convey the metal piece after extraction from a heating furnace. It is a figure which shows the example of a conventional hot rolling line. It is a schematic diagram of a continuous casting line.

Explanation of symbols

8 Metal piece 9 Width press
10 Heating furnace
12, R1, R2, R3 Rough rolling mill
14 Cropshire
15 Finishing-side thermometer
16 Descaling device
18, F1, F2 ... F7 Finishing mill
19 Work roll
21 Finishing side thermometer
22 Finishing side thickness gauge
23 Runout Table
24 coiler
25 Coiler inlet side thermometer
28 Continuous casting line
50 Control unit
70 process computer
90 Business computer
100 hot rolling line
101 traverse cart
102 loader
103 Thermal insulation pit
104 Loading table A Transport direction

Claims (1)

  Two pieces of metal having different timings fed to the hot rolling line, the total length of which is equal to or less than the length of the longest piece of metal entering the heating furnace of the hot rolling line Among the pieces, one piece supplied first is temporarily kept while keeping warm, and when one piece supplied later is supplied, two pieces of metal are arranged in the length direction. A method of charging a metal piece into a heating furnace in hot rolling, characterized by being charged into a heating furnace of a hot rolling line.

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