JP5761091B2 - Temperature control method and temperature control system for hot rolling line - Google Patents

Description

  The present invention relates to a temperature control method and a temperature control system for a hot rolling line.

  In the hot rolling line, the finishing mill entry side temperature and exit side temperature are determined in order to obtain a predetermined material, and as low as possible from the viewpoint of preventing the generation of scale flaws on the rough bar surface. desirable. With the purpose of lowering the temperature of the rough bar, the temperature adjustment pattern set according to various conditions such as temporarily retaining the rough bar between the stands of the rough rolling mill, increasing the number of rolling passes, etc. Coarse bar cooling is performed, but the rolling time increases, leading to production loss.

  In order to solve this problem, Patent Document 1 selects a section where the pitch is maximum when the rolled material is conveyed at an allowable maximum speed of equipment constituting the hot rolling line, and the selected section. The rolling method which adjusts the temperature of a rolling material with the installation of the area except for is disclosed.

  On the other hand, as a rough bar cooling method other than executing temperature adjustment by a rough rolling mill, Patent Document 2 discloses a rough rolling mill for rough rolling a rolled material and a finish rolling by a plurality of rolling stands arranged in tandem. Disclosed is a temperature control method for a hot rolling mill in which a cooling means is disposed between the rolling mill and the finish rolling mill temperature on both the inlet side and the outlet side of the rolling mill is controlled to a target temperature. .

JP 2006-289408 A JP 2008-212232 A

  In the above-mentioned Patent Document 1, the temperature adjustment of the rough bar is performed only in the rough rolling process, and the effect of eliminating the loss time of the temperature adjustment is small.

  In Patent Document 2, it is disclosed that a rough bar cooling device is provided to control both the entrance side rolling material temperature and the exit side rolling material temperature of the finish rolling mill to the target temperature. There is no disclosure of minimizing the temperature adjustment loss time by the machine.

  Then, this invention aims at reducing the temperature adjustment time in a rough rolling mill and eliminating a production loss.

In order to solve the above-mentioned problem, the first configuration of the present invention is provided with a bar cooling device and a bar heater between a rough rolling mill composed of a plurality of rough rolling stands and a finishing mill composed of a plurality of finishing rolling stands . A temperature control method for a hot rolling line,
From the temperature of the slab extracted from the heating furnace, rolling the rough slab without adjusting the temperature of the slab with a roughing mill, and the finish rolling entry side predicted temperature Tr when transported to the entrance of the finishing mill Seeking
The required temperature adjustment amount ΔTn is calculated by subtracting a preset finish rolling entry side target temperature T ₀ from the calculated finish rolling entry side predicted temperature Tr.
Determining whether the calculated required temperature adjustment amount ΔTn is within an allowable range;
When ΔTn is within an allowable range, temperature control is terminated without performing temperature adjustment by the bar cooling device, the bar heater, and the roughing mill,
When ΔTn exceeds the allowable range, it is determined whether ΔTn is positive or negative,
When ΔTn is positive, the maximum temperature adjustable amount ΔTmax of the bar cooling device is obtained based on the plate thickness of the coarse bar and the plate passing speed,
When ΔTn ≦ ΔTmax, the coarse bar is cooled using only the bar cooling device based on the value of the necessary temperature adjustment amount ΔTn,
When ΔTn> ΔTmax , a coarse bar is retained between the plurality of rough rolling stands or the plurality of rough rolling stands for cooling the temperature adjustment insufficient amount ΔTc = ΔTn−ΔTmax in the bar cooling device. Determine the temperature adjustment pattern to increase the number of rolling passes and cool the coarse bar,
Thereafter, the bar cooler cools the coarse bar with the maximum temperature adjustable amount ΔTmax as a set value,
When the necessary temperature adjustment amount ΔTn is negative, the rough bar is heated by the bar heater at a set value corresponding to the necessary temperature adjustment amount ΔTn.

  In this first configuration, a bar cooling device and a bar heater are provided between the roughing mill and the finishing mill, and the slab extracted from the heating furnace is cooled to the target temperature of the rough bar entering the finishing mill. The necessary temperature adjustment amount (necessary temperature adjustment amount) is calculated, and the necessary temperature adjustment amount is adjusted in the shortest possible time. That is, of the necessary temperature adjustment amount, the portion that can be cooled by the bar cooling device is cooled by the bar cooling device, and if the cooling is insufficient, cooling by the roughing mill, that is, temperature adjustment is performed. When the necessary temperature adjustment amount is negative, the coarse bar is heated to the target temperature by the bar heater. Thereby, the temperature adjustment time in rough rolling can be reduced and production loss can be eliminated.

The second configuration of the present invention, the temperature control method of a hot rolling line was installed bar cooling apparatus between the roughing mill and the rolling mill finishing consisting of a plurality of finish rolling stand comprising a plurality of rough rolling stand Because
In the heating furnace, a slab, a preset finish rolling entry side target temperature T _0, the absolute temperature drop amount when conveyed to rolling finishing mill entry side in the rough rolling mill without temperature adjustment And heat it so that it is higher than the temperature
From the temperature of the slab extracted from the heating furnace, obtain the finish rolling entry side predicted temperature Tr when rolled in the rough rolling mill and conveyed to the finish rolling mill entry side without performing temperature adjustment,
The required temperature adjustment amount ΔTn is calculated by subtracting a preset finish rolling entry side target temperature T ₀ from the calculated finish rolling entry side predicted temperature Tr.
Determining whether the calculated required temperature adjustment amount ΔTn is within an allowable range;
When ΔTn is within an allowable range, temperature control is terminated without adjusting the temperature by the bar cooling device and the roughing mill,
When ΔTn exceeds the allowable range, the maximum temperature adjustable amount ΔTmax of the bar cooling device is obtained based on the plate thickness of the coarse bar and the plate passing speed,
When ΔTn ≦ ΔTmax, the coarse bar is cooled using only the bar cooling device based on the value of the necessary temperature adjustment amount ΔTn,
When ΔTn> ΔTmax , a coarse bar is retained between the plurality of rough rolling stands or the plurality of rough rolling stands for cooling the temperature adjustment insufficient amount ΔTc = ΔTn−ΔTmax in the bar cooling device. The temperature adjustment pattern by the roughing mill that increases the number of rolling passes is determined and the rough bar is cooled,
Thereafter, the coarse bar is cooled by the bar cooling device using the maximum temperature adjustable amount ΔTmax as a set value.

In this second configuration, a bar cooling device is provided between the roughing mill and the finishing mill, and is necessary for cooling the slab extracted from the heating furnace to the target temperature of the rough bar entering the finishing mill. A temperature adjustment amount (necessary temperature adjustment amount) is calculated, and the necessary temperature adjustment amount is cooled in the shortest possible time. That is, of the necessary temperature adjustment amount, the portion that can be cooled by the bar cooling device is cooled by the bar cooling device, and if the cooling is insufficient, cooling by the roughing mill, that is, temperature adjustment is performed. Thereby, the temperature adjustment time in rough rolling can be reduced and production loss can be eliminated. Compared to the first configuration, the second configuration does not include a bar heater, so that the required temperature adjustment amount ΔTn is extracted from the heating furnace so that the heating by the bar heater is not performed. Keep the slab heated.
In the first and second configurations, whether or not temperature adjustment is to be performed is theoretically determined based on whether or not the required temperature adjustment amount ΔTn is 0. However, in reality, the temperature adjustment is performed based on equipment capacity or the like. An upper limit value and a lower limit value for determining whether or not to perform are set. In the present specification, the range between the upper limit value and the lower limit value is referred to as “allowable range”. Here, an allowable range may be set by providing an upper limit value and a lower limit value on the finish rolling entry side target temperature T ₀ .

  A third configuration of the present invention is a temperature control system including means for executing each step of the temperature control method for a hot rolling line according to the first configuration, and the bar cooling device and the bar heater are used for temperature adjustment. By using it, the temperature adjustment time in rough rolling can be reduced and production loss can be eliminated.

  The 4th structure of this invention is a temperature control system provided with the means to perform each step of the temperature control method of the hot rolling line which concerns on the said 2nd structure, By using a bar cooling device for temperature control The temperature adjustment time in rough rolling can be reduced and production loss can be eliminated.

  According to the present invention, the temperature adjustment in the roughing mill is determined by determining the temperature adjustment pattern by the roughing mill by reducing the required temperature adjustment amount by the roughing mill by the amount of temperature drop that can be cooled by the rough bar cooling device. Time can be reduced and production losses can be eliminated.

It is a block diagram which shows the system configuration | structure for implementing the temperature control method of the hot rolling line which concerns on Embodiment 1 of this invention. It is a flowchart which shows the procedure of the temperature control method of the hot rolling line which concerns on Embodiment 1 of this invention. It is a block diagram which shows the system configuration | structure for implementing the temperature control method of the hot rolling line which concerns on Embodiment 2 of this invention. It is a flowchart which shows the procedure of the temperature control method of the hot rolling line which concerns on Embodiment 2 of this invention.

Embodiments of the present invention will be specifically described below with reference to the drawings.
<Embodiment 1>
As shown in FIG. 1, a hot rolling line according to Embodiment 1 of the present invention includes a heating furnace 1 that heats a slab to a set temperature, and a rough rolling machine 2 that roughly rolls the slab extracted from the heating furnace 1. And a finish rolling mill 3 that finish-rolls the roughly rolled coarse bar, and a bar cooling device 4 and a bar heater 5 are installed between the rough rolling mill 2 and the finish rolling mill 3. The rough rolling mill 2 includes a plurality of rough rolling stands R1 to R4. The finish rolling mill 3 includes a plurality of finish rolling stands F1, F2, F3,.

The temperature control system for the hot rolling line according to the present embodiment includes an extraction temperature calculation unit 11 that calculates the temperature Ti of the slab extracted from the heating furnace 1, and the temperature Ti of the slab extracted from the heating furnace 1. From the finish rolling, the finish rolling entry side predicted temperature calculation unit 12 obtains the finish rolling entry side predicted temperature Tr when it is rolled by the rough rolling mill 2 and conveyed to the finish rolling mill entry side without temperature adjustment. A finish rolling entry side target temperature calculation unit 13 for calculating a finish rolling entry side target temperature T ₀ and a finish rolling entry side predicted temperature calculation unit 12 based on the material conditions such as the thickness, width, and steel type of the rough bar in the state. The required temperature adjustment amount ΔTn is calculated by subtracting the finish rolling entry side target temperature T ₀ calculated by the finish rolling entry side target temperature calculation unit 13 from the calculated finish rolling entry side predicted temperature Tr, and the thickness of the rough bar Bar cooling device 4 cooling from plate speed A temperature adjustment amount calculation unit 14 that calculates a maximum temperature adjustable amount ΔTmax that can be adjusted, a temperature adjustment pattern calculation unit 15 that calculates a temperature adjustment pattern by the roughing mill 2 from the necessary temperature adjustment amount ΔTn and the maximum temperature adjustment amount ΔTmax, The roughing mill control for controlling the roughing mill 2 based on the calculated temperature regulation pattern, for example, the temperature regulation pattern for retaining the rough bars between the roughing stands of the roughing mill 2 or increasing the number of rolling passes. Based on the apparatus 16, the bar cooling control device 17 that controls the bar cooling device 4 based on the temperature adjustment amount calculated by the temperature adjustment amount calculation unit 14, and the temperature adjustment amount calculated by the temperature adjustment amount calculation unit 14 And a bar heater control device 18 for controlling the bar heater 5.
In FIG. 1, a thermometer 19 is provided to confirm whether or not the temperature control of the present invention described below is performed as calculated.

  A temperature control procedure by the temperature control system having the above configuration will be described with reference to a flowchart shown in FIG.

Step 1
From the temperature Ti of the slab extracted from the heating furnace 1, a predicted finish rolling entry side temperature Tr when rolled by the roughing mill 2 and conveyed to the finish rolling mill entry side without temperature adjustment is obtained.

Step 2
A necessary temperature adjustment amount ΔTn is calculated by subtracting a preset finish rolling entry side target temperature T ₀ from the estimated finish rolling entry side temperature Tr obtained in step 1.

Step 3
Whether or not temperature adjustment is necessary is determined based on whether or not the necessary temperature adjustment amount ΔTn calculated in step 2 is within an allowable range. This allowable range is set in advance as ± 20 ° C., for example, in terms of facility capacity.

Step 4
When ΔTn exceeds the allowable range in the determination in step 3, it is determined whether ΔTn is positive or negative.

Step 5
If ΔTn is positive in the determination in step 3, the maximum temperature adjustable amount ΔTmax that can be cooled by the bar cooling device is obtained based on the plate thickness and plate passing speed of the rough bar.

Step 6
The required temperature adjustment amount ΔTn obtained in step 2 and the maximum temperature adjustable amount ΔTmax of the coarse bar cooling device 4 obtained in step 5 are compared.
Step 7
When ΔTn ≦ ΔTmax in the comparison of step 6, the coarse bar is cooled using only the bar cooling device 4 based on the value of the necessary temperature adjustment amount ΔTn.

Step 8
When ΔTn> ΔTmax in the comparison of step 6, the temperature adjustment pattern of the slab by the roughing mill 2 for cooling the temperature adjustment insufficient amount ΔTc = ΔTn−ΔTmax in the bar cooling device is determined to cool the rough bar. After that, the bar cooler 4 cools the coarse bar with the maximum temperature adjustable amount ΔTmax as a set value.

Step 9
If ΔTn is within the allowable range in the determination in step 3, the temperature control is terminated without adjusting the temperature by the bar cooling device 4, the bar heater 5, and the rough rolling mill 2.

Step 10
If the required temperature adjustment amount ΔTn is negative in the determination in step 4, the coarse bar is heated by the bar heater 5 with a set value corresponding to the required temperature adjustment amount ΔTn.

<Embodiment 2>
In the first embodiment described above, the control is performed in a hot rolling line in which both the bar cooling device 4 and the bar heater 5 are provided between the rough rolling mill 2 and the finish rolling mill 3, but in the second embodiment, As shown in FIG. 3, only the bar cooling device 4 is provided between the rough rolling mill 2 and the finish rolling mill 3, and the hot rolling line without the bar heater 5 is targeted. Other configurations in the second embodiment shown in FIG. 3 are the same as those in the first embodiment, and thus the description thereof is omitted.
Hereinafter, the temperature control method in the second embodiment will be described with reference to FIG.

Step 20
In the heating furnace 1, the slab is heated in advance so that the required temperature adjustment amount ΔTn becomes equal to or higher than the positive temperature. That is, the slab temperature Ti is a preset finish rolling entry side target temperature T _0, and a temperature decrease amount when the slab is rolled by the rough rolling mill 2 without adjusting the temperature and conveyed to the finish rolling mill entry side. It heats so that it may become higher than the temperature which added.

Step 21
From the temperature Ti of the slab extracted from the heating furnace 1, a finish rolling entry side predicted temperature Tr when rolled by the roughing mill 2 and conveyed to the finish rolling mill entry side without adjusting the temperature is obtained.

Step 22
The necessary temperature adjustment amount ΔTn is calculated by subtracting a preset finish rolling entry side target temperature T ₀ from the estimated finish rolling entry side temperature Tr obtained in step 21.

Step 23
Whether or not the temperature adjustment is necessary is determined based on whether or not the necessary temperature adjustment amount ΔTn calculated in step 22 is within an allowable range. This allowable range is set in advance as ± 20 ° C., for example, in terms of facility capacity.

Step 24
When ΔTn is within the allowable range in the determination of step 23, the temperature control is finished without performing the temperature adjustment by the bar cooling device 4 and the rough rolling mill 2.

Step 25
The maximum temperature adjustable amount ΔTmax that can be cooled by the bar cooling device 4 is obtained based on the plate thickness and the plate passing speed of the coarse bar.

Step 26
The required temperature adjustment amount ΔTn calculated in step 22 is compared with the maximum temperature adjustment amount ΔTmax of the bar cooling device 4 obtained in step 23.

Step 27
When ΔTn ≦ ΔTmax in the comparison in step 26, the coarse bar is cooled using only the bar cooling device 4 based on the value of the necessary temperature adjustment amount ΔTn.

Step 28
When ΔTn> ΔTmax in the comparison in Step 26, the temperature adjustment pattern of the slab by the roughing mill 2 for cooling the temperature adjustment insufficient amount ΔTc = ΔTn−ΔTmax in the bar cooling device is determined to cool the rough bar. After that, the bar cooler 4 cools the coarse bar with the maximum temperature adjustable amount ΔTmax as a set value.

  As described above, according to the first and second embodiments of the present invention, the temperature adjustment pattern by the roughing mill is reduced by reducing the required temperature adjustment amount by the roughing mill by the amount of temperature drop that can be cooled by the rough bar cooling device. By determining the temperature, it is possible to reduce the temperature adjustment time in the rough rolling and eliminate the production loss.

DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Rough rolling mill 3 Finish rolling mill 4 Bar cooling device 5 Bar heater 11 Extraction temperature calculating part 12 Finish rolling entrance side estimated temperature calculating part 13 Finish rolling entrance side target temperature calculating part 14 Temperature adjustment amount calculating part 15 Temperature adjustment Pattern calculation unit 16 Rough rolling mill control device 17 Bar cooling control device 18 Bar heater control device 19 Thermometer

Claims (4)

A temperature control method for a hot rolling line in which a bar cooling device and a bar heater are installed between a rough rolling mill composed of a plurality of rough rolling stands and a finishing mill composed of a plurality of finish rolling stands ,
From the temperature of the slab extracted from the heating furnace, rolling the rough slab without adjusting the temperature of the slab with a roughing mill, and the finish rolling entry side predicted temperature Tr when transported to the entrance of the finishing mill Seeking
The required temperature adjustment amount ΔTn is calculated by subtracting a preset finish rolling entry side target temperature T ₀ from the calculated finish rolling entry side predicted temperature Tr.
Determining whether the calculated required temperature adjustment amount ΔTn is within an allowable range;
When ΔTn is within an allowable range, temperature control is terminated without performing temperature adjustment by the bar cooling device, the bar heater, and the roughing mill,
When ΔTn exceeds the allowable range, it is determined whether ΔTn is positive or negative,
When ΔTn is positive, the maximum temperature adjustable amount ΔTmax of the bar cooling device is obtained based on the plate thickness of the coarse bar and the plate passing speed,
When ΔTn ≦ ΔTmax, the coarse bar is cooled using only the bar cooling device based on the value of the necessary temperature adjustment amount ΔTn,
When ΔTn> ΔTmax , a coarse bar is retained between the plurality of rough rolling stands or the plurality of rough rolling stands for cooling the temperature adjustment insufficient amount ΔTc = ΔTn−ΔTmax in the bar cooling device. Determine the temperature adjustment pattern to increase the number of rolling passes and cool the coarse bar,
Thereafter, the bar cooler cools the coarse bar with the maximum temperature adjustable amount ΔTmax as a set value,
When the required temperature adjustment amount ΔTn is negative, the hot bar is heated by the bar heater at a set value corresponding to the required temperature adjustment amount ΔTn. A temperature control method for a hot rolling line in which a bar cooling device is installed between a rough rolling mill composed of a plurality of rough rolling stands and a finishing mill composed of a plurality of finish rolling stands ,
In the heating furnace, a slab, a preset finish rolling entry side target temperature T _0, the absolute temperature drop amount when conveyed to rolling finishing mill entry side in the rough rolling mill without temperature adjustment And heat it so that it is higher than the temperature
From the temperature of the slab extracted from the heating furnace, obtain the finish rolling entry side predicted temperature Tr when rolled in the rough rolling mill and conveyed to the finish rolling mill entry side without performing temperature adjustment,
The required temperature adjustment amount ΔTn is calculated by subtracting a preset finish rolling entry side target temperature T ₀ from the calculated finish rolling entry side predicted temperature Tr.
Determining whether the calculated required temperature adjustment amount ΔTn is within an allowable range;
When ΔTn is within an allowable range, temperature control is terminated without adjusting the temperature by the bar cooling device and the roughing mill,
When ΔTn exceeds the allowable range, the maximum temperature adjustable amount ΔTmax of the bar cooling device is obtained based on the plate thickness of the coarse bar and the plate passing speed,
When ΔTn ≦ ΔTmax, the coarse bar is cooled using only the bar cooling device based on the value of the necessary temperature adjustment amount ΔTn,
When ΔTn> ΔTmax , a coarse bar is retained between the plurality of rough rolling stands or the plurality of rough rolling stands for cooling the temperature adjustment insufficient amount ΔTc = ΔTn−ΔTmax in the bar cooling device. The temperature adjustment pattern by the roughing mill that increases the number of rolling passes is determined and the rough bar is cooled,
Then, the temperature control method for a hot rolling line, wherein the bar is cooled by the bar cooling device with the maximum temperature adjustable amount ΔTmax as a set value. A temperature control system for a hot rolling line in which a bar cooling device and a bar heater are installed between a rough rolling mill composed of a plurality of rough rolling stands and a finishing mill composed of a plurality of finish rolling stands ,
A step of obtaining a predicted finish rolling entry side temperature Tr when the slab is extracted from the heating furnace and rolled by the rough rolling mill and conveyed to the finishing mill entry side without adjusting the temperature of the slab by the rough rolling mill. When,
Subtracting a preset finish rolling entry side target temperature T ₀ from the calculated finish rolling entry side predicted temperature Tr to calculate a necessary temperature adjustment amount ΔTn;
Determining whether or not temperature adjustment is necessary based on whether or not the calculated required temperature adjustment amount ΔTn is within an allowable range;
When ΔTn is within an allowable range, the temperature control is terminated without adjusting the temperature by the bar cooling device, the bar heater, and the roughing mill; and
A step of determining whether ΔTn is positive or negative when ΔTn exceeds an allowable range;
When ΔTn is positive, obtaining the maximum temperature adjustable amount ΔTmax of the bar cooling device based on the plate thickness of the coarse bar and the plate passing speed;
Comparing the required temperature adjustment amount ΔTn with the maximum temperature adjustable amount ΔTmax of the bar cooling device;
When ΔTn ≦ ΔTmax, cooling the coarse bar using only the bar cooling device based on the value of the necessary temperature adjustment amount ΔTn;
When ΔTn> ΔTmax , a coarse bar is retained between the plurality of rough rolling stands or the plurality of rough rolling stands for cooling the temperature adjustment insufficient amount ΔTc = ΔTn−ΔTmax in the bar cooling device. The temperature adjustment pattern by the roughing mill that increases the number of rolling passes is determined and the rough bar is cooled,
Then, the step of cooling the coarse bar with the maximum temperature adjustable amount ΔTmax as a set value by the bar cooling device,
When the required temperature adjustment amount ΔTn is negative, the step of heating the rough bar with the bar heater at the set value according to the required temperature adjustment amount ΔTn without performing the temperature adjustment with the rough rolling mill and the bar cooling device. And a temperature control system for a hot rolling line. A temperature control system for a hot rolling line in which a bar cooling device is installed between a rough rolling mill composed of a plurality of rough rolling stands and a finishing mill composed of a plurality of finish rolling stands ,
In the heating furnace, a slab, a preset finish rolling entry side target temperature T _0, the absolute temperature drop amount when conveyed to rolling finishing mill entry side in the rough rolling mill without temperature adjustment Heating to a temperature higher than the sum of the values ,
From the temperature of the slab extracted from the heating furnace, rolling the rough slab without adjusting the temperature of the slab with a roughing mill, and the finish rolling entry side predicted temperature Tr when transported to the finishing mill entry side Seeking steps,
Subtracting a preset finish rolling entry side target temperature T ₀ from the calculated finish rolling entry side predicted temperature Tr to calculate a necessary temperature adjustment amount ΔTn;
Determining whether or not temperature adjustment is necessary based on whether or not the calculated required temperature adjustment amount ΔTn is within an allowable range;
ΔTn said bar cooling system when in the allowed range, the steps of terminating the temperature control without temperature adjustment by us and the rough rolling mill,
When ΔTn exceeds an allowable range, obtaining a maximum temperature adjustable amount ΔTmax of the bar cooling device based on a plate thickness of the rough bar and a plate passing speed;
Comparing the required temperature adjustment amount ΔTn with the maximum temperature adjustable amount ΔTmax of the bar cooling device;
When ΔTn ≦ ΔTmax, cooling the coarse bar using only the bar cooling device based on the value of the necessary temperature adjustment amount ΔTn;
When ΔTn> ΔTmax , a coarse bar is retained between the plurality of rough rolling stands or the plurality of rough rolling stands for cooling the temperature adjustment insufficient amount ΔTc = ΔTn−ΔTmax in the bar cooling device. The temperature adjustment pattern by the roughing mill that increases the number of rolling passes is determined and the rough bar is cooled,
Then, a means for performing a step of cooling the rough bar with the maximum temperature adjustable amount ΔTmax as a set value by the bar cooling device is provided.

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