KR20050020004A - Device for manufacturing high strength wires and the method thereof - Google Patents

Abstract

PURPOSE: To provide high strength wire rod manufacturing apparatus and method capable of skipping lead patenting process that is a heat treatment by manufacturing high carbon steel wire rod of which tensile strength is improved as much as about 10 to 15% compared with ordinary wire rods using both mist nozzles and spray nozzles capable of atomizing cooling water particles. CONSTITUTION: The method for manufacturing high strength wire rod comprises: a step of piling up a ring shaped hot rolled wire rod coil on a conveyor, the hot rolled wire rod coil continuously coiled through a down coiler; a step of driving the conveyor to transfer the wire rod coil that is continuously piled up on the conveyor; a mist spraying step of dividingly cooling the wire rod coil according to degree of overlapping by spraying different quantities of cooling water mist onto a central part and side surface parts of the wire rod coil that are divided according to overlapping density difference; and a step of cooling the wire rod coil by supplying cold air to the wire rod coil from the lower side of the wire rod coil while the wire rod coil is transferred on the conveyor. The apparatus for manufacturing high strength wire rod comprises: a conveyor(60) for transferring a ring shaped wire rod coil(C) continuously discharged from a down coiler(40) at a constant speed; cooling covers(70) installed on in upper part of the conveyor; large quantity mist nozzles installed at the inner side of the cooling covers to spray a large amount of mist type cooling water to side surface parts of the wire rod coil in which overlapping density between the coils is high; and small quantity mist nozzles(81) installed at the inner side of the cooling covers to spray a small amount of mist type cooling water to a central part of the wire rod coil in which overlapping density between the coils is low.

Description

High strength wire rod manufacturing apparatus and manufacturing method {DEVICE FOR MANUFACTURING HIGH STRENGTH WIRES AND THE METHOD THEREOF}

The present invention relates to a wire rod manufacturing apparatus, and more particularly, to a high strength wire rod manufacturing apparatus and manufacturing method which can prevent the occurrence of cooling deviation of the wire rod and improve the strength through the forced injection of fine droplets through the mist nozzle and spray nozzle It is about.

Wire rod refers to the round bar of the material to produce a variety of wires by the stretch process, and is manufactured in the form of a coil of 5.5mm ~ 20mm in diameter by hot rolling.

1 shows a wire rod manufacturing line used for cooling such wire rods. As shown in FIG. 1, the apparatus for manufacturing wire rod includes a heating furnace 10 for heating a billet, a rolling mill 20 for hot rolling a heated billet, and a water cooling device for cooling a hot rolled billet ( 30) is connected to the rear end of the water cooling apparatus 30, and includes a winding machine 40 for winding the wire rod, and a Stelmore cooling facility 50 for transferring while cooling the wound wire rod.

The wire rod manufacture in the apparatus for wire rod manufacture of FIG. 1 consists of the following processes. The billet is first heated to a constant temperature in a furnace. The billet heated to a constant temperature is transferred and hot rolled into a plurality of rolling mills 20, for example, a block mill, and the diameter is gradually reduced while repeating the cooling process with a plurality of cooling devices 30. It is processed to a suitable diameter of 5.5 ~ 20.0mm. The wire rod thus processed is deformed from a straight line to a non-concentric coil while passing through the winding machine 40 at the rear end of the hot rolling facility, and then transferred to a state of being placed on the roller of the Stelmore cooling facility 50. . The wire rod deformed in the form of a concentric coil is conveyed on a conveyor made of rollers and forcedly cooled by a blower of a forced blower installed at the bottom of the conveyor. The wire rod can secure the desired tensile strength and tensile strength devation on the consumer side through this cooling process.

In the case of manufacturing such a wire rod, a hot water method or a DLP method has been conventionally used as a method of cooling the wire rod, but recently, a method using a Stelmore cooling facility as described above has been widely used. The Stelmore cooling unit was co-developed by Stetelco and Morgan in Canada in 1964 and is now widely used around the world.

In wire rod cooling, first, the hot rolled wire rod is deformed into a coil form using a winding head, which is a winding machine, so that the cross section is circular. Stallmore cooling equipment for cooling the wire rods passed through this process is a device for forcibly cooling the wire rod conveyed on the roller by forcibly blowing air from the blower installed in the lower roller while transferring the wire rod dropped on the roller toward the aggregator.

5 shows a cross-sectional view in the width direction of the Stelmore cooling facility 50. As shown in FIG. 5, the Stelmore cooling facility 50 blows air upward from the lower blower 63 while forcibly transferring the wire rod coil to the roller 51 to cool the wire coil.

As shown in the Stelmore cooling plant, the coil is cooled while falling from the winder 40 onto the conveyor of the Stelmore cooling plant 50. In this case, since the hot wire falls to the conveyor while drawing a concentric circle of about 1070 mm in diameter, on the conveyor, there is a central portion, which is a portion having a high overlap density, and a center having a relatively low overlap density, on the conveyor. When the wire rod is cooled by forcibly blowing air from the lower part of the conveyor in this state, a problem arises in that the cooling temperature variation of the wire rod increases in proportion to the overlap density difference. This problem is more serious when producing high carbon steel wire, which is a high carbon steel grade. In particular, when the structure cannot be homogenized due to the cooling temperature deviation generated from the overlap density difference when the wire rod is cooled by the forced air, there is a problem in that a disconnection occurs due to a large tensile strength deviation during processing on the consumer side. In addition, since 1990, consumers can omit the lead patenting process, which is the first heat treatment process performed by the consumer, and when drawing wires, high strength and high toughness can be reduced to the maximum. Since there is a demand for products with characteristics, the commercialization of such products is a general trend.

In order to solve the above-mentioned problems and satisfy the needs of the consumer, various methods for homogenizing the wire structure by making the cooling temperature uniform during the wire rod cooling have been studied.

As one of the methods for commercializing high-strength, high toughness products, a mist cooling facility (formerly TOA Mist Patemting) installed in Japan Future Enterprise, for example, is exemplified. In this case, the cooling medium is introduced into a mist mixed with water and air, and the spray medium is directly cooled to the wire rod product through the coaxial reciprocal collision of water and air and atomization of particles. It is to improve the mechanical properties of wire rod products by achieving strength improvement and uniformity of variation compared to mower coolant.

The description of the mist cooling method and the patent of the wire rod factory in Japan Future Enterprise (Japan Future Enterprise) is well described in Japanese Patent Laid-Open Nos. 10-17943 and US Patent 5-125-987 and 5-146-759.

However, in the case of JF's Japan Future Enterprise mist cooling, it has the advantage that it is possible to simply develop an independent cooling system utilizing the characterization of the mist nozzles without the overall modification of the existing Stallmore cooling system. It also has the disadvantage of guaranteeing the change in pressure of air and water through the spray nozzle and the resulting particle size and velocity of uniform particles.

In addition, there is a problem in that the tensile strength value for each part comes from the difference in overlap density generated during wire fabrication and cooling, in which case the strength of each part is uniformly controlled through the fine particle diameter control of the nozzle shape of the wire center and the side of the nozzle. Although the spray pattern is set to correct, it is difficult to improve the strength of each part in comparison with the conventional material, which is basically a stealmo coolant.

It also has a disadvantage that can lead to poor wire rod product quality due to uneven strength due to the multiplexing management of the nozzle.

Accordingly, the present invention has been made in order to solve the above problems, by mixing the mist nozzle and the spray nozzle capable of atomizing the particles mixed with the steel wire rods improved tensile strength of about 10 to 15% as compared to the general material as a whole It is an object of the present invention to provide a high-strength wire rod manufacturing apparatus and a manufacturing method which can omit the lead patenting process, which is a heat treatment process.

Another object of the present invention is to provide a high strength wire rod manufacturing apparatus and a manufacturing method which can prevent the occurrence of tensile strength deviation through uniform cooling of the wire rod coil.

In order to achieve the object as described above, the present invention, the difference in density by site by controlling the cooling ability between the side portion and the center of the wire wound by coiling in accordance with the difference in the overlap density for each wire diameter inevitably generated according to the position The idea is to minimize the difference in cooling capacity from the system so that a uniform product is obtained throughout the coil length.

To this end, the method of manufacturing a high strength wire rod according to the present invention comprises the steps of: depositing a hot rolled wire coil in the form of a ring wound continuously through a winding machine on a conveyor, and transferring the wire rod continuously stacked at a predetermined linear speed by driving the conveyor. Discharging a different amount of refrigerant in the form of mist in each of the central and side portions of the wire rod coils classified according to the overlap density difference, and cooling the wire rod coils according to the overlapping degree. Supplying the wire to cool the wire coil.

In addition, the manufacturing method further includes spraying the refrigerant in the form of a spray in the center of the wire coil with the mist-type spray.

On the other hand, the manufacturing apparatus of the present invention for producing a high-strength wire according to the above-described manufacturing method is provided with a mist nozzle for spraying the refrigerant in the form of a mist on the conveyor on which the wire is moved, the mist nozzle is a small amount of relatively small mass flow rate The mist mist nozzle is divided into a mist mist nozzle having a relatively high mass flow rate, and the mass mist nozzle is installed toward the side of the wire coil having a high overlap density between coils, and the mist mist nozzle is installed toward a center having a relatively low overlap density. It is structured.

In addition, the present invention has a structure to increase the speed of the conveyor to prevent overcooling of the coil side portion and to suppress bainite or martensite structure, which is a low temperature structure.

In addition, the present invention is further provided between a small amount of mist nozzles for spray nozzles for spraying the refrigerant in the form of a spray to compensate for the drop in cooling capacity of the wire coil center as the conveyor speed increases.

Therefore, the present invention is a mass mist nozzle having a high mass flow rate on the side part based on the cooling cover cross section, a small mist nozzle having a relatively low mass flow rate than the side part at the center portion, and a small amount of the mist nozzle between the center portion to improve the cooling performance of the central part. The spray nozzle is installed.

Here, the mist refers to the case where the particle size is between 10-100 μm, and the spray refers to the case where the particle size is 100 μm or more.

In addition, the center of the wire rod coil refers to the area where the overlap density of the wire rod is the lowest along the width direction of the conveyor, and the side portion means the area where the overlap density of the wire rod is the highest.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is a schematic cross-sectional view showing a Stelmore cooling facility is installed high strength wire rod manufacturing apparatus according to the present invention, Figure 3 is a view showing a nozzle of the high strength wire rod manufacturing apparatus according to the present invention, Figure 4 is Accordingly, a schematic diagram showing a state in which the refrigerant is sprayed in the form of a mist or a spray on the wire rod.

According to the above drawings, the apparatus includes a conveyor 60 for transferring the wire rod C continuously discharged in a ring form from the winder 40 at a constant speed, and a cooling cover installed on the conveyor 60. (70) is installed inside the cooling cover (70), the mass mist nozzle (80) for spraying a large amount of mist-type cooling water toward the side of the coil of the wire rod having a high overlap density between the coils and the cooling cover (70) And a small amount of mist nozzles 81 for spraying a small amount of coolant in the form of mist toward the center with a low degree of overlap between coils, and are provided between the small amount of mist nozzles 81 to spray coolant in the form of a spray toward the center of the strip. And a spray nozzle 90.

In addition, a blower 61 and an air injection duct 62 for forcibly blowing cooling air to the wire rod C on the conveyor 60 are installed below the conveyor 60.

Each mist nozzle (80, 81) is a cooling water line 830 and air line (84) for supplying the cooling water and air to one side of the nozzle as shown in Figure 3 in order to spray the cooling water to a droplet size of 10-100㎛ ) Is connected to the structure, the mass flow rate is sprayed according to the hole size of each nozzle tip (82).

Accordingly, in the case of conventional spray cooling, the nozzle tip having a relatively large hole size is used in the side portion of the wire coil C having a high overlap density to improve the cooling performance, and in the case of the center where the overlap density is low Relatively small nozzle tips are used to induce uniform cooling throughout the coil.

In this case, considering the characteristics of the nozzle, it can be seen that the flow rate of the water flowing into the nozzle tip can be changed by the pressure change of the air which directly affects the cooling capacity among the factors in which the spray cooling proceeds. Heat wire and heat flux are changed to cool the hot wire, but in this case, the tensile strength at the center is about 10kg / mm2 higher than the side part, so the quality deviation due to the variation of cooling temperature Has the disadvantage of being poor.

Therefore, according to the separate use of the mass mist nozzle 80 and the small amount of mist nozzle 81 as described above, the cooling temperature variation for each wire part can be reduced, but basically by controlling the heat flux generated from the overlap density difference It can be concluded that to cool the coil uniformly, additional cooling is required, whether at the center of the coil or on the side of the wire coil.

For reference, as a result of several field tests, cooling of the side of the wire coil was sufficiently performed, whereas in the case of the center, the cooling strength was insufficient, resulting in low tensile strength value. Simultaneous injection cooling test was performed for a long time, but the local low temperature structure occurred in the side and center where the mass flow rate was high, resulting in an error of not being recognized as a product.

Therefore, it is preferable that the time that the cooling proceeds be performed in a range of about 10 to 12 seconds.

Because the cooling capacity of this mist nozzle can be cooled by 30 degrees per second on average, if the cooling is performed at a longer time than that, there is a high possibility of low temperature structure.

For reference, in the case of the hard wire (SWRH72B) tested in the example, the cooling time was limited as described above because the onset temperature at which martensite, which is a low temperature structure, was generated, was approximately 500 ° C.

Therefore, as a structure for improving the cooling ability of the center without generating low-temperature structure when the cooling proceeds based on the above contents, the apparatus includes a mist between the small amount mist nozzles 81 installed at the center of the wire coil (C). It is a structure in which the spray nozzle 90 for spraying cooling water in the form of a spray rather than a form spray is provided.

As mentioned above, the cooling method by mist and the cooling method by spray are basically different in the technical idea. Typically, the case where the size of the cooling particles is between 10 μm and 100 μm is referred to as mist particles, and the case of 100 μm or more is classified as spray particles. In addition, in the case of mist cooling, an inflow structure of air and water is required to induce cooling, and the configuration of facilities such as a cooling water pipe, an air pipe, and a chamber is required to support the cooling of the mist. It is very complicated. In addition, in the case of the mist method, the particles collide with the linear flow of kinetic energy of the air to atomize and cool the particles due to surface tension crushing. Is high. However, in the case of spray injection cooling, the surface tension of the liquid column due to the change in the pressure of pure water is crushed without inflow of air. Holds.

In addition, unlike the mist method, the particle size of the sprayed particles is relatively large, and the flow rate distribution is increased, thereby increasing the heat transfer surface q of the hot wire surface, thereby improving the cooling capacity.

Heat flux in this spray cooling zone (Heat Flux, Q) is as follows.

Q = hs (Ts-Twater)--------(1)

Where Ts is the hot wire surface temperature, Twater is the temperature of the coolant flowing into the spray, and hs is the convection temperature heat transfer coefficient. In this case, the spray water is used, and it can be redefined as the following equation using the non-amount (W) and the surface temperature (Ts) of the high-temperature wire that affect the heat transfer coefficient (hs).

hs = a W ^b Ts ^c -------(2)

Here, a, b, and c are empirical coefficients that are experimentally determined according to the type of nozzle used, the arrangement method, and the properties of the high temperature wire, and can be derived by calculating the surface temperature and heat transfer of the high temperature wire.

However, when the atomized mist particles come into contact with the hot wire surface and the cooling proceeds, the cooling phenomenon due to evaporation is accelerated initially but the cooling is delayed due to the boiling phenomenon after a certain time. To have a problem that may also have a problem of cooling imbalance.

This problem is related to the mist nozzles used in the side parts with relatively high overlap densities and the relatively low center parts, and in this case, the difference in speed affecting cooling occurs more and more, and thus the variation in the tensile strength value, which is the quality of each part, occurs. It is the cause of the deterioration. In order to solve this problem, spray nozzles 90, such as the present invention, have been installed to improve the cooling capability between the side mass mist nozzles 80 and the small amount of mist nozzles 81 at the center, thereby minimizing the deviation between the tensile strength values.

Figure 4 schematically shows a state in which the refrigerant is sprayed in the form of a mist or spray on the wire rod in accordance with the present invention.

As shown in FIG. 4, when the optimum stelmore conveyor 60 speed is limited to 0.5 m / sec to 0.85 m / sec to cool the wire rod coil C at a high temperature, the wire rod center and side portions according to spray injection cooling are cooled. As the mass flow rate of the liver is superimposed, the tensile strength value, which is a quality between the center and the side part, is not only improved, but also the cooling part is terminated prematurely due to the increase of the speed of the conveyor 60, so that martensite and bainite, Bainite) There is no formation of structure and the strength is enhanced by the influence of the coolant particles sprayed in the center as well, so that the strength is improved and uniform cooling is performed over the wire coil.

On the other hand, in the present embodiment, when looking at the mass flow area when spraying the mist form, the mist nozzle represents an elliptic mass flow area of 150 mm in length and 100 mm in width, and the spray nozzle 90 has a width of 520 mm in width. The mass flow area in the form of 30-50 mm is shown. The mass flow rate shape as described above has the advantage that the cooling control in the longitudinal direction (x-axis) is advantageous when the hot wire proceeds in the width direction (y-axis), as shown in FIG. By superimposing and cooling the mass flow rate between nozzles, it is possible to produce products with improved strength and uniformity.

5 shows the distribution of particle diameters in the length and width directions of the spray nozzle used in the present invention. 5a shows the change in mass flow rate per minute according to the pressure change. In this case, it shows the amount of 18 to 27 liters / min when the pressure is changed from 2.0kg / cm2 to 5.0kg / cm2, and in FIG. 5b, the particle size distribution of the particles in the longitudinal direction (0 to 520mm) is shown when the unit nozzle is sprayed. have.

According to the figure, the spray center shows a particle size distribution of about 250 μm, and the particle size distribution tends to increase as it proceeds to both sides, showing a particle size distribution of 400 to 425 μm.

In consideration of the above characteristics of the spray nozzle, in the case of the center part, the overlap density is relatively lower than that of the side part. Since it is about 3 times higher, the spray spray particle diameter is increased to differentiate the cooling capacity from the side and the center to induce cooling structure uniformity.

At this time, the cooling capacity was measured by measuring the temperature from the temperature at which the material cooling starts to the end of the transformation to the interval at which the transformation was completed, and converting the distance into time.

In the case of hard steel wire as shown in Table 1, the temperature range of starting cooling is finished at 850 ° C to 520 ° C. In this case, a cooling capacity of about 35 ° C / sec to 42 ° C / sec is obtained.

Example

In this example, the continuous cast billet of high carbon steel hard steel wire (JIS SWRH72B) having the chemical composition shown in Table 1 was hot rolled to a diameter of 8.0mm∮ and then cooled to a cooling start temperature range of 830 to 850 ° C. . Winding the linear wires thus cooled in a concentric circle through a winding machine 40 called a laying head, and then forced air blowing on the cooling conveyor 60 to the 500 ° C range where the cooling transformation is terminated under the manufacturing conditions as shown in Table 2 below. Forced cooling by was performed.

fairyland Chemical composition (wt%) Remarks C Si Mn P S 8.0 mm (SWRH72B) 0.68-0.75 0.15-0.30 0.60-0.90 0.03 0.07 -

standard Dimensions (mm∮) Rolling speed (m / sec) Winding temperature (℃) Conveyor 60 Speed (m / s) Blower Speed (%) Ring spacing (mm) Light Steel (SWRH72B) 8.0 45-50 800 ~ 850 0.4-1.0 20 37-63

At this time, in order to minimize the cooling temperature difference generated in the heat flux between the high temperature wire center and the side portion and the overlap density generated during the conventional mist cooling, a small amount of the mist nozzle (81) ) And a large amount of mist nozzles (80) to spray the cooling water in the form of mist on the center and side of the coil, and a spray nozzle (90) between the small amount of mist nozzles (81) to the small amount of mist nozzles (81) The mass flow rate area by the spray nozzle 90 was superimposed on the mass flow area area by the mass flow nozzle area and the mass flow area by the mass mist nozzle 80 to induce cooling increase and decrease and uniform cooling.

The installation section of this apparatus was limited to the 8.4-meter section, which is a section where transformation starts by mist cooling and ends transformation. For reference, the mist nozzle installation section is 8.4 meters with two 4.2 meter covers 70 installed. The number of installation of the spray nozzle 90 was limited to 32 per cover 70. The reason for limitation is that the small amount of mist nozzles 81 are installed in two rows of two upper portions of the cover 70 so that the small amount of mist nozzles 81 is limited to the number of small amount of mist nozzles 81.

Cooling conditions at this time was wound at a winding temperature of 800- ~ 850 degrees as shown in Table 3 below was carried out by limiting the conveyor speed from about 0.5 to 0.85m / sec.

The reason for limiting the coiling temperature is 830 ~ 850 degrees because the grain size for inducing micronization of grains during transformation in austenite tissue is too large at 850 degrees or more, so it is hard to proceed to refine the grains. It was limited to more than 800 degrees to limit the winding temperature as described above in order to suppress the formation of low-temperature tissue by local wire supercooling during mist cooling.

In addition, the speed of the conveyor 60 is limited by the occurrence of martensite structure caused by the supercooling of the mist and spray cooling at 0.5 m / sec or less, and the transformation in the cooling section according to the present invention is less than 0.9 m / sec. At the same time, the tensile strength improvement was limited to less than the target value, which allows the customer's new process to be omitted.

The effect analysis before and after installation by this invention is represented by Table 3.

The cooling test of Table 3 below was performed by changing four test factors for the Stallmore cooling target material and the mist cooling material which are ordinary materials.

At this time, the characteristic of tensile strength is to select three random wire coils (C) and reselect one ring, which is a representative sample for each coil. Obtained.

As shown in Table 3, as a result of using the present invention, the tensile strength value was improved by 9 to 10%, and the deviation was improved to 2.0kg / mm2 or less as compared to the conventional Stelmore coolant.

division Winding temperature (℃) Conveyor 60 Speed (m / s) Use of Spray Nozzle Tensile Strength by Wire Coil Part (kg / ㎠) Remarks value Deviation Normal materials -1 (Stelmor) 830 0.78 unused 103.0 1.50-1.60 - Normal material-2 (Mist) 845 0.85 unused 109.7 2.45 - Invention material (1) 835 0.40 to 0.50 use 113.1 3.25 Ms occurrence Invention material (2) 830 0.70 use 112.5 2.95 Ms not occurring Invention material (3) 845 0.85-0.90 use 112.1 1.85 " Invention material (4) 840 > 0.90 use 107.3 2.35 "

As shown in Table 3 above, after the continuous rolling of the hard steel wire (SWRH72B) 8.0 pie, which is a conventional material, in four cases, the spray and mist are sprayed and cooled in four cases at the same time. In the case of the first invention, the tensile strength value is 103 kg, which is usually Stelmore material. The result of 113.1kg / mm2 improved by about 10% compared to / mm2, and the deviation was 2.16 times worse than that of conventional 1.5kg / mm2. It could be confirmed that this occurred. In the case of Inventive Material-1, the test was promoted by lowering the speed of the Stelmore conveyor 60 to 0.4 to 0.5 m / sec in order to lengthen the time for the wire cooling to proceed. In this case, some subcooling occurred in the section where the mass flow rate between the spray injection section and the side mist injection section where the mass flow rate is relatively high overlapped, resulting in a phenomenon that the product was not recognized as a value. In this case, similarly to Inventive Material-1, some supercooled structures were generated in a section where the mass flow rate between the spray jet section and the side mist spray section where the mass flow rate was relatively high overlaps with each other, thereby failing to be recognized as a product.

Therefore, when using the present invention, the Stelmore conveyor (60) speed should be maintained at 0.5m / sec or more to obtain a test result that the low-temperature tissue is not generated by using the coolant Stelmore conveyor (60) speed is 0.5m / sec Limited to above.

In the case of Inventive Material 2, the injection test was carried out at 0.7 m / sec, which is 0.2 m / sec higher than the Inventive Material 1, under the same cooling spraying conditions. In this case, the tensile strength value of 112.5kg / mm2 was improved by 9.2% compared to the normal stelmore material, but the deviation was 2.16kg / mm2, which is 1.44 times poorer than 1.5kg / mm2, which is the normal stealth material 2.16kg / mm2. It was confirmed that the result was obtained.

However, the strength value is satisfactory compared to the normal material, but the deviation value of tensile strength affecting the disconnection process during the customer's wire drawing process is 2.16kg / mm2 higher than that of the normal material. Insufficient level can be said.

In addition, in the case of Inventive Material 3, a spray test was performed in a state in which the speed of the conveyor 60 was increased to 0.8 to 0.85 m / sec under the same cooling spray conditions. In this case, the tensile strength value was improved by 112.1kg / mm2, which was 9.0% higher than that of the Stelmor material, and the deviation was 1.87kg / mm2, which is less than 2.0kg / mm2, compared to 1.5kg / mm2, which is usually Stelmor material. Results of comparable quality levels were obtained. In addition, it was confirmed that martensite tissue, a low temperature tissue generated in some tests, was not generated. Typically, the tensile strength deviation desired by the customer in the direct drawing process is less than 2.0kg / ㎜.

However, in the case of Inventive Material 4, unlike the previous experiment, the Stelmore conveyor 60 speed was increased from 0.9 m / sec to 1.0 m / sec to analyze the spray test and the quality result. As shown in FIG. 8, when the speed of the conveyor 60 is 0.9 m / sec or more, the time for the material staying in the section where the cooling is performed is shorter than that of the invention materials 1 to 3, and sufficient cooling is evenly distributed at each wire part. As a result, the overall tensile strength was lowered and the variation in tensile strength remained at 2.35kg / mm2 below the level desired by the customer.

Therefore, in case of cooling by reinforcing spray cooling method to the existing mist cooling method, when the conveyor 60 speeds below 0.5m / sec, the local cooling of the wire part is excessively proceeded to confirm that low temperature tissue is generated. In addition, when the wire 60 is cooled by advancing the speed of the conveyor 60 to 0.9 m / sec or more, the time for which the material stays in the mist and spray cooling sections is shortened, and thus sufficient cooling cannot be obtained. Therefore, when using the present invention, in order to obtain the mechanical properties of the tissue desired by the customer Stelmore conveyor 60 speed was limited to less than 0.9m / sec at 0.5m / sec or more.

As described above, the present invention is an invention for controlling the cooling temperature that directly affects the tensile strength value and the deviation of the wire rod product. The spray nozzle is disposed between the mist nozzles installed on the mist cover 70 when the wire rod is cooled by the conventional mist cooling. By installing the Stallmore conveyor 60, the effect of reinforcing the tensile strength value drop due to the increase and decrease of the speed and thereby the effect of reducing the cooling temperature variation for each wire part.

As described above, the present invention as described above is an invention for controlling the cooling temperature which directly affects the tensile strength value and the deviation of the wire rod product. Spray nozzles are installed between the nozzles to reinforce the drop in tensile strength due to the increase and decrease of the Stelmore conveyor speed, thereby reducing the cooling temperature variation of each wire part.

In addition, mist and spray spraying is carried out at the upper part, and cooling by forced air is carried out at the lower part, so that uniform distribution of particles caused by disturbances can be carried out to a high temperature material, so that a wire rod product which can omit the heat treatment process of customers can be manufactured. Will be.

1 is a view showing a typical wire rod manufacturing line,

Figure 2 is a schematic cross-sectional view showing the Stelmore cooling facility is installed high-strength wire production apparatus according to the present invention,

3 is a view showing a nozzle of the high-strength wire rod manufacturing apparatus according to the present invention,

Figure 4 is a schematic diagram showing a state in which the refrigerant is sprayed in the form of a mist or spray on the wire rod in accordance with the present invention,

Figure 5a is a graph showing the change in mass flow rate per minute according to the pressure change of the spray nozzle according to the present invention,

5 is a graph showing the particle size distribution of particles in each longitudinal direction during the nozzle spray of the spray nozzle according to the present invention;

Figure 6 is a schematic cross-sectional view showing a Stelmore cooling facility according to the prior art.

Claims (8)

Depositing a ring-shaped hot rolled wire coil continuously wound on a conveyor; Driving the conveyor to transfer wire rods that are continuously stacked at a predetermined linear speed; Mist spraying step of separately cooling the wire coil according to the degree of overlap by spraying a different amount of cooling water in the form of mist in each of the central portion and the side portion of the wire coil divided by the overlap density difference, Cooling the wire coil by supplying cold air to the wire coil from the lower portion during the conveyor transfer High strength wire rod manufacturing method comprising a. The method of claim 1, wherein the mist spraying step is to produce a high-strength wire, characterized in that for spraying a relatively small amount of cooling water in the mist form in the center of the wire coil, and spraying a relatively large amount of cooling water in the mist form on the side portion. Way. The method of manufacturing a high strength wire rod according to claim 1, wherein the linear speed of the conveyor is 0.5-0.90 m / sec. 4. The method of claim 3, further comprising spraying cooling water in the form of a spray in the center of the wire coil as well as mist spraying as the linear speed of the conveyor increases. 4. The method for producing a high strength wire rod according to claim 3, wherein the sprayed cooling water particles have a particle diameter of 250 to 425 µm, a flow rate of 18 to 27 liters / min, and a cooling capacity of 35 to 42 ° C / sec. Conveyor for transporting the wire rod coil continuously discharged from the winder in the form of a ring at a constant speed, a cooling cover installed at the upper portion of the conveyor, and a mist form toward the side of the wire coil having a high density of overlap between coils. A high-strength wire rod manufacturing apparatus comprising a large amount of mist nozzle for spraying a large amount of cooling water, a small amount of mist nozzle for spraying a small amount of mist-type cooling water toward the center of the coil cover is installed inside the cooling cover is low. 7. The high strength wire rod manufacturing apparatus according to claim 6, wherein the linear speed of the conveyor is 0.5-0.90 m / sec. 8. The apparatus of claim 7, wherein a spray nozzle for spraying cooling water in the form of a spray toward the center of the strip as the linear velocity of the conveyor increases is further installed between the small amount of mist nozzles.