KR100507573B1 - Method for cooling wire-rod with controlled rolling and apparatus for cooling the same - Google Patents

Abstract

The present invention relates to a cooling method and apparatus for wire rod cooling, the object of which is generated by the difference in density between the coil center portion and the edge portion (EDGE) in the vertical direction of the coil during the slow cooling operation of the hot-rolled wire rod It is to reduce the cooling speed deviation and material deviation.

Therefore, in order to achieve the above object, the present invention, and the central portion (C1) of the wire rod coil 10 during the initial cooling of the wire rod coil 10 is extracted and dropped through the rolling process to the cooling conveyor belt (20) Applying cold air to a portion having a high accumulation density so as to reduce a temperature deviation caused by a difference in the accumulation density between edge portions C2, and hot air generated by heat exchange due to cold air of the wire rod coil 10 at the rear end of the conveyor. While providing a method of cooling the wire rod comprising the step of applying to the coil portion where the deviation occurs,

In the first chamber 32 below the conveyor 20 to apply cold air F1 to the wire rod 10 at the initial position T1 of the cooling conveyor 20 in which the wire rod coil 10 which has undergone the rolling process is extracted and dropped. It is installed, the cold wind control means 30 for adjusting the direction of the cold wind according to the difference in the density of the loading of the wire rod 10, and the hot air (F2) applied to the wire rod 10 heat exchanged at the rear position of the conveyor 20 It is installed in the second chamber 62 in the rear position of the conveyor to which the hot air pipe 50 connected on the slow cooling cover 40 is applied, and adjusts the direction of the hot air F2 according to the temperature deviation of the wire rod 10. It provides a wire rod cooling device comprising a hot air control means (60).

Description

TECHNICAL FOR COOLING WIRE-ROD WITH CONTROLLED ROLLING AND APPARATUS FOR COOLING THE SAME}

The present invention relates to a wire rod cooling method and an apparatus thereof, and more particularly, to cooling caused by a density difference between a coil center portion and an edge portion (EDGE) in a coil traveling direction and a vertical direction during a slow cooling operation of a hot rolled wire rod. The present invention relates to a wire cooling method and apparatus for reducing the variation of the wire structure by reducing the speed deviation and material deviation, thereby obtaining a uniform structure and mechanical properties of the wire rod.

In general, in the manufacture of wire rods, billets produced through smelting, steelmaking, and continuous casting processes are first rolled into wire rods, that is, rough rolling (R1), intermediate rolling (R) in FIG. 3, and final. It is manufactured as a coil as a winding machine through a rolling process such as filament rolling (R3) and a water cooling stand. During this process, the coils fall in a circular shape on the Stelmor cooling conveyor and are constantly stacked.

That is, as shown in Figure 1, the wire coil 100, the coil is moved in a circular shape on the cooling conveyor is moved to the center portion (C1) and the edge of each of the wire ring (100 ') in the vertical direction As the number of overlapping parts between EDGE and C2 is small and large, the difference in density is significant. This is because the distance D between the center parts is larger than the distance between edge parts. However, the density difference between the center portion and the edge portion during the movement of the conveyor 110 of the wire rod 100 is different from the cooling rate for each part where the material is slowly cooled at room temperature, which results in a cooling deviation.

In other words, the edge portion (C2) of the relatively high accumulation density on the conveyor has a lower cooling rate than the central portion (C1) is extracted without completely completing the tissue transformation until exiting the cover of the slow cooling zone, such as The untransformed part cools down as fast as 5 ° C as it comes into contact with the atmosphere as it is extracted from the cover.

Therefore, while there is a site where the transformation is completed from the AUSTENITE tissue to the PEARLITE tissue in the cover, that is, the central portion C1 of the wire rod 100 having a relatively low density, the density is as described above. The edge of the relatively high edge tissue is rapidly cooled in contact with the atmosphere in a completely untransformed state, resulting in tissues such as martensite or bainite, which are mild, resulting in a tensile strength far higher than normal. As a result, a significant tensile strength deviation is caused between the center portion and the edge portion of the coil wire 100, so that an additional heat treatment operation for the uniformity of the tissue is inevitable before the drawing or the secondary processing operation is performed in a later process.

At this time, in order to avoid such a non-uniform phenomenon of the structure, it is necessary to reduce the density difference according to the overlapping portion between the central portion (C1) and the edge portion (C2) of the wire rod coil 100 on the conveyor, to reduce such a density difference The method is to increase the space between the rings 100 'in the coil, that is, the space between the rings, which reduces the density of the edge portion C2 and reduces the density difference with the center portion.

However, to increase the ring spacing of the wire coil 100 as described above is to increase the conveying speed of the conveyor or lower the rolling speed when the material falls on the cooling conveyor 110 in the winder, reducing the speed of the conveyor having a certain length The slow cooling period of the wire coil 100, that is, the time to stay in the cover is reduced, and thus, the complete transformation of the tissue due to the slow cooling is not achieved, and thus, the quenching structure is quenched during the extraction of marbasite (MARTENSITE) or bainite In order to reduce the slow cooling time, a method of increasing the length of the slow cooling cover part has been developed.

However, it is impossible to completely solve the problems caused by the density difference between the center portion and the edge portion of the wire coil 100 described above, and thus the temperature deviation problem of slow cooling due to the density difference cannot be completely solved.

That is, as shown in FIG. 2, the above-described temperature deviation T1-Tf of the wire coil 100 is lower than that at the initial cooling time point P1 at which the wire coil 100 falls on the conveyor after winding. At the time of extraction (Pf) is further increased, due to the deepening of the temperature deviation, if the cooling rate is adjusted based on the central portion (C1) of the wire coil 100, the edge portion (C2) portion of the tissue until the time to exit the cover Complete metamorphosis is not complete.

In order to solve the problems caused by the temperature deviation generated during the slow cooling of the wire rod coil, conventionally, a low cooling system (SLOW COOLING SYSTEM) for adjusting the cooling function by supplying hot air from the lower part of the conveyor or insulated cover on the upper part of the conveyor. The heating device was installed to adjust the cooling function deviation of the material.

However, the above methods require an additional heat source facility to supply a separate heat source, and there is a control difficulty of inputting as many heat sources as necessary by accurately predicting the density difference between the center and the edge parts according to the specification of the material.

The present invention has been made in order to improve the various problems as described above, the object of the present invention, by performing a controlled rolling in the rolling step of manufacturing the billet wire, by performing a controlled cooling of the cooling deviation generated by cold, hot air The present invention provides a control rolling for wire rod cooling, and a method of cooling the wire rod including the same, and a device for reducing the material deviation caused by the temperature variation of each part of the wire coil in a short cooling section.

As a technical configuration for achieving the above object, the present invention, the temperature deviation due to the difference in the stacking density between the central portion and the edge portion of the wire rod coil during the initial cooling of the wire coil extracted and dropped by the cooling conveyor belt through the rolling process Applying cold air to a site having a high accumulation density to reduce the amount;

It provides a method of cooling the wire rod to perform uniform cooling of the wire rod coil in the cooling conveyor section, including the step of applying the hot air generated by heat exchange due to the cold air of the wire coil to the coil portion where the temperature deviation occurs in the rear end of the conveyor. By

In addition, as another aspect of the present invention, the wire coil subjected to the rolling process is installed in the first chamber of the lower side of the conveyor in order to apply cold air to the wire rod at the initial position of the cooling conveyor is extracted and dropped, cold air according to the difference in the loading density of the wire rod Cold wind control means for adjusting the direction of the;

 It is installed in the second chamber at the rear position of the conveyor to which the hot air pipe connected on the slow cooling cover is applied to the hot air applied to the wire rod and heat exchanged at the rear position of the conveyor, and adjusts the direction of the hot air according to the temperature deviation of the wire rod. By providing a cooling device of the wire rod including a control means.

First, the wire rod cooling method according to the present invention in detail as follows.

3 is a graph showing a temperature distribution of a wire rod according to a wire rod cooling method including control rolling for wire rod cooling according to the present invention in comparison with conventional rolling and cooling, and FIG. 4 is a method and apparatus for cooling a wire rod according to the present invention. The overall configuration for explaining.

That is, as shown in Figures 3 and 4, the present invention is characterized in that the cooling method of the wire rod is not only the cooling process of the wire rod 10 but also by controlling the rolling process wire rod even in the cooling conveyor section shorter than the existing cooling conveyor section. In order to obtain a uniform structure and uniform mechanical properties while eliminating the temperature deviation of each part.

First, as shown in FIG. 3, the rolling process of the present invention will be described in detail as follows. Such a rolling process, that is, control rolling, can be performed simultaneously or separately with the control cooling part as described in detail below. have.

That is, since the finish rolling process, that is, the final rolling process (R3 of FIG. 3) during the wire rod manufacturing from the billet, the rolling progresses at a high speed of approximately 100 m / sec, generates a high heat generation during processing, and thus the internal structure It causes recrystallization at a very high speed, so dislodge and vacancy are not retained in the tissue during rolling.

On the other hand, as shown in Figure 3, after the billet is extracted from the heating furnace and passed through the rough rolling (R1 of Figure 3) the material is subjected to the first intermediate pre-cooling (PRE-COOLING) (W1) After cooling to the non-recrystallized region, the first control rolling, that is, intermediate rolling (R2) is performed, and the process heat generated during the intermediate rolling (R2) of the first control rolling stage is secondly intermediate water cooling (PRE-COOLING). When the material is cooled to the unrecrystallized area through W2 and the secondary control rolling to finish-roll the material (R3 in FIG. 3) is performed again, the material temperature is increased by normal rolling, that is, the heat generated during rolling. Unlike normal rolling, which does not control the rising, the dislocation density (DISLOCATION DENSITY) rapidly increases within the material, and the grains are also very fine.

At this time, the control rolling described above is different from the usual rolling method, the rolling work of rough rolling (R1), intermediate rolling (R2) and finish (final) rolling (R3) is the same as described above, It is to pass through the intermediate water cooling (W1) (W2), usually after continuing to perform the whole rolling operation to the end to go through the water cooling stage.

Next, the wire rod cooling method of the present invention for cooling the wire coil 10 having an increased electric potential density and fine grains on the cooling conveyor 20 through the aforementioned control rolling will be described in detail.

As shown in FIG. 4, when the wire coil 10 including a lot of deformation energy inside the material through the control rolling falls on the cooling conveyor 20 through the control rolling, that is, cold external air introduced from the outside. The cold air F1 is directed to the edge portion C2 of the wire rod 10 having a relatively high stowage density of the wire rod 10 so that the edge temperature of the wire rod 10 is relative to the center portion. This results in an inverse temperature deviation (P1 in FIG. 6A) that is made lower.

Next, the hot air F2 generated by the heat exchange with the wire rod 10 in the cold air applied at the initial position of the cooling conveyor 10 generates a temperature deviation at the rear end of the conveyor 20 through the hot air pipe 50 and the blower. It is applied to the coil part again.

Therefore, even when a cooling deviation is generated between the central portion and the edge portion of the coil due to the difference in the deposition density, when the wire rod 10 exits the slow cooling cover 40, the temperature deviation between the central portion and the edge portion of the coil disappears and the difference in the storage density difference occurs. Regardless, the transformation will be completed, which will not cause the tensile strength deviation of the wire rod.

That is, as shown in Figures 3 and 6, in the prior art, while the central portion of the wire rod in the conveyor section first, the temperature difference between the central portion (C1) and the edge portion (C2) at the point of time Pf, but it can be seen that the present invention, In the P0-P1 section where cold air (F1) is concentrated on the wire edge (C2) during control cooling after the control rolling, the temperature of the edge (C2) decreases sharply, and at the time of Pf, the center (C1) It can be seen that the temperature deviation between the edge and the edge portion (C2) disappears.

In the case of ordinary rolling, recrystallization occurs in the material as the temperature of the material rises due to the heat of processing generated during rolling, and the deformation energy generated during the processing is consumed in the recrystallization process. However, precipitates generated during cooling cannot grow sufficiently, and these precipitates prevent growth of grains and cause variation in tensile strength.

By the way, in the case of controlled rolling which performs intermediate water cooling during the rolling operation as in the present invention, since the rolling proceeds in the unrecrystallized region, it contains many deformation energy even after rolling, and the internal energy sufficiently grows the precipitates (MC, MN). Therefore, the grains in the tissue can be sufficiently grown, so that the tensile strength can be lowered and the strength variation of each part can be reduced.

Next, the cooling device of the wire rod according to the present invention will be described in detail as follows.

4 and 5 show a cooling apparatus of the present invention, such a cooling apparatus is largely provided with cold air control means 30 and hot air control means 60, the cold air control means 30 is a rolling process The coarse wire coil 10 is installed in the first chamber 32 below the conveyor 20 to apply cold air F1 to the wire rod 10 at the initial position T1 of the cooling conveyor 20 in which the coarse wire coil 10 is extracted and dropped. The direction of the cold wind is adjusted according to the difference in deposition density of the wire rod 10.

The hot air control means 60 is connected to the slow cooling cover 40 such that the cold air F1 is applied to the wire rod 10 so that the heat exchanged hot air F2 is applied at the rear position T2 of the conveyor 20. It is installed in the second chamber 62 of the conveyor rear position T2 to which the hot air pipe 50 is connected, and adjusts the direction of the hot air F2 according to the temperature deviation of the wire rod 10.

Meanwhile, a blower 34 for blowing external air and hot air into the first and second chambers 32 and 62 in the hot air pipe 50 connected to the first 32 and the second chamber 62. 64 are respectively installed, and air blowing nozzles 36 and 66 are respectively installed between the chambers 32 and 62 and the conveyor 10.

Next, the respective control means 30 and 60 are installed to divide the wind direction into the central portion C1 and the edge portion C2 of the wire rod 10 in the first and second chambers 32 and 62. On the partition member 30a, a damper 30b disposed below the partition member 30a to separate and block the cold and hot air inflow into the chambers 32 and 62, and the upper part of the partition member 30a. It comprises a deflector (30c) for controlling the wind direction so that the cold and hot air introduced into the chamber as a damper (30b) is applied to the center and the edge of the wire rod 10, the configuration of controlling the direction of the cold and hot air.

Referring to the operation of the cooling device of the present invention having such a configuration as follows.

As shown in Figures 4 and 5, when the wire coil 10, which has undergone the control rolling or the conventional rolling process of the present invention is extracted and dropped in the rolling line to reach the initial position of the cooling conveyor 20, the conveyor The blower 34 connected to the lower part of the first chamber 32 installed below the 20 operates to introduce external cold air, that is, cold air F1, into the first chamber 32 side.

At this time, the two dampers 30b on the lower side of the partition member 30a installed in the first chamber 32 and installed to divide the cold air into hot air, that is, into the central portion C1 and the edge portion C2 of the wire rod 10. ) Is rotated to the left and right to block the air flow path between the two partition wall members 30a toward the center of the wire rod 10 and open the air path toward the wire rod edges on both sides, while the cold air (F1) is blown through the partition wall member The deflector 30c at the lower side of the slow cooling cover 40 installed on the upper portion of the 30a flows left and right so that cold air is applied to the edge of the wire rod 10. By being applied to the edge portion of the relatively high wire rod 10, the temperature deviation between the center portion and the edge portion of the wire rod 10 is reduced while the reverse temperature deviation, that is, the wire edge portion C2, is rather hotter than the central portion C1. Generates a reverse temperature deviation that cools.

Next, the cold air to be applied to the high temperature wire rod 10 is converted to hot air by heat conversion and sent as a blower 64 to the rear portion of the cooling conveyor 20 through the hot air pipe 50 installed on the slow cooling cover 40. On the ground, the hot air control means 60 in the second chamber 62 installed below the conveyor 20 downwardly, that is, the damper 60b under the partition member 60a is hot air like the cold air control means 30. The direction of is applied to the site where the temperature deviation is severe, that is, the temperature is low, and the final direction of such hot air is controlled by the deflector 60c provided on the partition member 60a.

On the other hand, the blowing conditions of the cold air (F1) and the hot air (F2) as shown in Figure 4, the pyrometer (PYROMETER) installed in the middle of the initial and rear portion of the conveyor, that is, the sensor (S) (S ') (S The temperature is determined by the "), and the temperature difference between the center part and the edge part of the wire rod 10 by applying hot air to the site where the temperature deviation of the coil is generated by predicting the final structure and mechanical properties expected by the density difference. This can be minimized.

Hereinafter, an embodiment of the present invention will be described.

EXAMPLE

Titanium-added steel, which is a welding rod wire among wire rods, adds about 0.2% titanium to improve welding efficiency and ARC stability. Such titanium is re-dissolved during heating and finely precipitated during rolling. Precipitation hardening occurs, causing large variation in tensile strength between the center and edge of the coil during cooling.

Therefore, when the wire rod 10 is disconnected around the quenched tissue part, ie, martensite or bainite, during the drawing operation, the wire rod 10 is made of a fail pack and then fed for welding. Degradation of the feedability may cause instability of the arc and uneven welding surface.

In order to solve such a problem, when the material is subjected to the control rolling and control cooling according to the present invention, it can be seen that the tensile strength is lowered and the deviation between the center and the edge part is greatly reduced, which is shown in Table 1 below. .

On the other hand, in the normal rolling and normal cooling disclosed in Figure 3, after the material is extracted in the heating furnace during the initial rolling proceeds the temperature of the material is lowered after the strain rate (STRAIN RATE) after the processing heat is generated and the temperature of the material Is raised, the method of not controlling the rise of the temperature of the material by the processing heat is a common rolling method.

In addition, the conventional cooling method is to cover only the slow cooling cover 40 on the conveyor 20, so that the coil is slow cooling only in the slow cooling cover 40, in the case of applying such a conventional cooling method, the edge portion of the coil wire (10) It can be seen that the martensite fraction in is greatly increased, the organization of which is shown in FIG.

Table 1 below shows changes in the structure of the wire rods according to the conventional cooling method of the present invention.

division Tensile strength (kg / ㎣) Tensile strength deviation between wire rods (kg / ㎣) Fraction of martensite Normal rolling + normal cooling (conventional) 55.9 3.20 3-4 v / o Normal rolling + control cooling 52.2 1.98 1-2 v / o Control Rolling + Control Cooling (Invention) 49.1 0.36 0-0.5 v / o

(The detailed structure state of the fraction of martensite is shown in (a)-(c) of FIG. 7)

That is, as shown in Table 1 and FIG. 7, when the controlled cooling in the present invention is performed in the conventional normal rolling, the martenside fraction is slightly reduced, but the tensile strength at the center and the edge of the wire rod 10 is still reduced. It can be seen that there is a deviation.

However, when the control rolling and control cooling according to the invention is carried out, it can be seen that the tensile strength and the fraction of martensite are extremely low, which gives the time for the titanium carbide (Titanium Carbide) to sufficiently precipitate and grow. This is because the growth is lowered in tensile strength, and because the transformation in the slow cooling cover 40 is completed, the fraction of martensite is also lowered.

As described above, according to the wire rod cooling method and apparatus of the present invention, the wire rod coil having a uniform structure and characteristics by reducing the temperature deviation caused by the difference in the pile density between the center portion and the edge portion of the wire rod coil during the cooling operation of the wire coil. It is possible to produce an excellent effect.

While the invention has been shown and described with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit or scope of the invention as set forth in the claims below. I would like to know that those who have knowledge of this can easily know.

1 is a schematic view showing a wire coil deposited on a general cooling conveyor.

2 (a) and 2 (b) are graphs showing a temperature distribution of a wire rod according to a conventional conveyor position and a temperature deviation between a center portion and an edge portion of the wire rod in FIG. 1.

Figure 3 is a graph showing the temperature distribution of the wire rod according to the wire rod cooling method according to the present invention, including the control rolling for the wire rod cooling according to the conventional conventional rolling and cooling

Figure 4 is an overall configuration for explaining the present invention the method and apparatus for cooling the wire rod.

5 is an overall view including a cross-sectional view taken along line A-A and line B-B of Figure 4 showing the present invention wire rod cooling apparatus.

6 (a) and (b) are graphs showing the temperature distribution of the wire rod and the temperature deviation between the center portion and the edge portion of the wire rod with respect to the conveyor position according to the present invention.

7A to 7C are tissue state diagrams related to Table 1 in the detailed description showing changes in wire characteristics when the conventional rolling and the control rolling and control cooling of the present invention are performed.

Explanation of symbols on main parts of drawing

10 .... wire rod 20 .... conveyor

30 .... cold air control means 60 ... hot air control means

C1, C2 .... Center and edge of wire rod

F1, F2 .... cold and hot wind S, S ', S ".... sensors

T1, T2 .... Conveyor Initial and Rear Positions

Claims (6)

During the initial cooling of the wire coil 10 which is extracted and dropped to the cooling conveyor belt 20 through the rolling process, the temperature deviation is caused by the difference in the pile loading density between the central portion C1 and the edge portion C2 of the wire rod coil 10. Applying cold air (F1) to the site of high accumulation density to reduce; And, Including the step of applying the hot air (F2) generated by the heat exchange by the cold wind of the wire coil 10 to the coil portion where the temperature deviation occurs at the rear end of the conveyor to perform uniform cooling of the wire coil in the cooling conveyor section. Cooling method of wire rod, characterized in that configured The method of claim 1, wherein the rolling step, After the billet is extracted from the heating furnace during the hot rolling of the material, after performing the first intermediate pre-cooling (W1) to cool the processing heat generated during the rough rolling of the roughly rolled (R1) material, the material Primary control rolling to intermediate rolling (R2); And, After the second step of cooling the process heat generated during the intermediate rolling (R2) of the first control rolling step through the second pre-cooling (W2) to the second control rolling to finish the material (R2) finish rolling. Cooling method of wire rod comprising control rolling, characterized in that the configuration The method of claim 1, wherein applying the initial cold air of the wire coil 10 includes setting cold air conditions according to the difference in deposition density for each coil size and cooling speed on the conveyor 20. Is obtained based on the temperature deviation between the center portion C1 and the edge portion C2 of the wire rod 10 obtained as a plurality of sensors S, S ', S "provided in the traveling direction of the conveyor 20. Cooling method of wire rod In the first chamber 32 below the conveyor 20 to apply cold air F1 to the wire rod 10 at the initial position T1 of the cooling conveyor 20 in which the wire rod coil 10 which has undergone the rolling process is extracted and dropped. Cold air control means 30 is installed, and adjusts the direction of the cold wind in accordance with the difference in the density of the loading of the wire (10); And,  In the rear position of the conveyor T2 to which the hot air pipe 50 connected on the slow cooling cover 40 is connected so that the hot air F2 applied to the wire rod 10 and heat-exchanged is applied at the rear position T2 of the conveyor 20. Installed in the second chamber 62, the cooling device for the wire rod, characterized in that it comprises hot air control means 60 for adjusting the direction of the hot air (F2) in accordance with the temperature deviation of the wire rod (10). The hot air pipe (50) connected to the first (32) and the second chamber (62) is configured to blow external air and hot air into the first and second chambers (32, 62). Blowers 34 and 64 are respectively provided, and between the chambers 32 and 62 and the conveyor 10, air blow nozzles 36 and 66 are respectively installed. Device 5. The cold air control means (30) and the hot air control means (60) according to claim 4, wherein the center portion (C1) and the edge portion (C2) of the wire rod (10) in the first and second chambers (32, 62). Partition members (30a, 60a) which are installed to divide the wind direction into; A damper (30b) (60b) installed at the lower portion of the partition member (30a) so as to separate and separate cold air and hot air inlet into the chambers (32) (62); And, And a deflector (30c) (60c) for controlling the wind direction so that cold and hot air drawn into the chamber as a damper (30b) is applied to the upper portion of the partition member (30a) to the center portion and the edge portion of the wire rod (10). Chiller of wire rod