JPH0362771B2 - - Google Patents

Description

[Detailed description of the invention]

B. Field of Industrial Application This invention relates to a direct patenting method and apparatus for performing direct patenting by immersing a medium-high carbon steel wire rod in hot water. B. Prior Art In order to improve cold workability and increase tensile strength of medium-high carbon steel wire rods manufactured by hot rolling steel slabs, the wire rods are usually subjected to a patenting treatment to form a fine pearlite structure before wire drawing. This heat treatment is usually carried out by the so-called lead patenting method, in which the wire is processed to a temperature of 850°C or higher and then continuously immersed in a molten lead bath of about 450 to 650°C. The processability and mechanical performance of the obtained wire are good. Also, the so-called air patenting method, in which the wire is reheated and patented by controlled cooling, such as by blowing cold air onto it, is also widely used because it is simple. However, since these methods involve reheating the wire at room temperature, each method requires separate equipment and personnel for reheating and the work, resulting in high costs. In contrast, a direct patenting method has been developed in which the hot-rolled high-temperature wire is directly controlled and cooled to produce a wire with properties equivalent to those of the patented wire by reheating it. It is widely used because it can reduce costs. There are various methods for this direct patenting method, but among these methods, the method of cooling the rolled wire rod in hot water is highly evaluated because of its simplicity of equipment and low cost of operation. Unlike cold water, cooling with hot water creates a film of water vapor on the surface of the high-temperature wire, resulting in a so-called film boiling phenomenon, which avoids direct contact between the steel and hot water and slows down the cooling rate. In this case, a cooling rate suitable for the patenting process can be obtained, and a wire rod with a fine pearlite structure can be obtained. A known example of its application is a patenting process in which medium-high carbon steel wire is immersed in boiling water. As shown in FIG. 1, a specific example of the device is to form a wire rod 1 rolled in a finishing rolling mill 13 into a coil shape in a laying type winding machine 2, and then directly feed it into hot water in a hot water tank 4. 3 and immersed in hot water in a spiral pattern, and placed on the horizontal conveyor 10 installed directly below the winder 2 as a continuous non-concentric ring-shaped coil with the center of the coil shifted little by little. The water is transferred while being cooled, and taken out of the hot water tank by an inclined conveyor 11 and a carry-out conveyor 12. In this case, the temperature of the hot water is practically always maintained approximately at the boiling point of the cooling liquid by the heat input from the hot wire being immersed. C. Problems to be Solved by the Invention This direct patenting treatment method using boiling water has a faster cooling rate than other treatment methods using air cooling, so although it has the characteristic that the tensile strength of the resulting wire is high, it is still difficult to perform lead patenting treatment. In order to compensate for this, the diameter of the rolled wire rod is increased to increase the total wire drawing process up to the product wire diameter, similar to other methods. However, in cooling using boiling water, the heat transfer coefficient is almost constant, so for thin wires such as 5.5 mmφ, the cooling rate is high, but for wires of 8 mmφ or more, the overall cooling rate is small, resulting in a decrease in tensile strength. The problem is that increasing the degree of processing is no longer sufficient to cover product performance and costs. Therefore, efforts are being made to improve the hot water patenting method so as to obtain a tensile strength comparable to that of lead patenting, if possible. The following methods have been proposed so far. (a) Pre-cooling the material before immersing it in boiling water (Japanese Patent Publication No. 55-16217) (b) Increase the cooling rate by creating a relative speed between the hot water and the wire by circulating the hot water in a fluidized manner (Japanese Patent Publication No. 54-68718) (c) Processing under pressure higher than atmospheric pressure (Japanese Patent Publication No. 54-68718)
−98915) (d) Process hot water at a temperature below the boiling point (subcooled state). However, among these methods (a), it is difficult to stabilize the pre-cooling conditions and there is a high risk of forming martensite and bainite, and in (b) it is impossible to provide a large flow velocity and high tensile strength cannot be obtained. . Also(c)
has not been put into practical use due to many problems in terms of equipment. (d)
If the temperature of hot water is lowered by 1℃, it will be approximately 0.25Kg/mm ²
It was observed that there was a slight increase in tensile strength at 45°C.
The treatment up to this point is well known, but at temperatures below 90°C there is actually a greater risk of the fatal phenomenon of locally forming martensite or bainite.
Proposal to maintain the temperature at 90℃ or above (patent application 1983-
64894, Japanese Patent Application Laid-Open No. 177933/1983), it has not been put into practical use. Even if it were possible to suppress the generation of supercooled structures such as martensite, in order to apply this method (d) directly to the patenting method, it would be necessary to maintain the temperature of the hot water at a low temperature below the boiling point. When directly patenting is performed immediately after hot rolling, the wire rod brings an enormous amount of heat into the hot water per unit time. It is necessary to stop the rise in water temperature using a heat exchanger, and these unresolved problems must be resolved for practical use. In addition, when hot water is used as a coolant, the change in heat transfer coefficient due to temperature changes is significantly greater than that of oil, so it is necessary to strictly control the water temperature within a narrow range. It is difficult to maintain uniformity under heat treatment conditions. Therefore, in the current immediate patenting method using hot water, the temperature of the hot water (water temperature) is actually kept at the boiling point and all of the heat brought in by the wire is removed by the heat of evaporation of the water. Even this is 8mm
This is because thin wire rods with a diameter of less than φ can provide sufficient tensile strength, and the cooling conditions are stable as the water temperature is kept constant near the boiling point, which has the advantage of reducing variations in the tensile strength of the wire rods. . At the start of work, the hot water is heated to near the boiling point, and after that, the temperature is not controlled and is left to boiling as the wire rods are immersed.Therefore, the water temperature is always between 95 and 100, including natural cooling and temperature reduction due to make-up water. ℃
The actual situation is that the temperature is within the range of , and therefore direct patenting in a subcooled state below the boiling point has not been carried out. In addition, the applicant has published Japanese Patent Application Publication No. 55-83642 (Japanese Patent Application Publication No. 57-83642)
No. 9826), we proposed a heat treatment method in which a large amount of gas is blown into a hot liquid and a high-temperature metal material is immersed in the liquid under strong stirring. In this case, it is possible to provide a greater relative velocity between the metal object and the liquid than in the conventional method, and the cooling rate can be increased, so in this sense it can be said to be an improvement over the method (b). When this invention is applied to general metal materials, there is no problem even if the process is performed in a subcooled state, but when this invention is applied to patenting medium-high carbon steel wire, simply blowing in a large amount of air will keep the temperature close to the boiling point. It is predicted that the temperature of the hot water in the dripping hot water tank will rapidly drop far below the boiling point and martensite and bainite will occur on the surface of the wire, so some other method will be used to heat the hot water to maintain the water temperature near the boiling point. When patenting was performed by blowing air at 20/m ² seconds or more, an improvement in tensile strength of about 5 kg/mm ² was observed, and this is an example of the invention of Japanese Patent Application No. 5,583,642. As explained above, in the known industrial methods to date, treatment in a subcooled state is not carried out due to the risk of generation of martensite and bainite and the difficulty of temperature control, and the tensile strength is improved by the patenting heat treatment. At most 5Kg/ ^mm2
This has not yet reached the level of lead patenting. D. Disclosure of the Invention The present invention uses a direct patenting method in which a medium-high carbon steel wire rod is placed in hot water, and the heat that balances the amount of heat brought in by the high-temperature wire rod is extracted mainly by blowing a large amount of air into the hot water. The wire rod is patented while maintaining the temperature of the water uniformly in the tank by keeping the temperature below 95℃ and strong stirring by air blowing.
The present invention provides a hot water direct patenting method and an apparatus therefor, which can stably obtain the same tensile strength as lead patenting treatment even in the above-mentioned thick wire. The inventors have invented the above-mentioned invention (Japanese Patent Application No. 83642/1983).
Subsequently, a new attempt was made to patent the wire rod by simply blowing air into hot water close to the boiling point without using any heating means, using medium-high carbon steel wire rods.As a result of various studies, it was determined that the amount of heating by the input wire rod could be reduced. If enough air is blown into hot water to remove the excess amount of heat, as the amount of air increases, the water temperature will easily drop to below 95°C.On the other hand, if the water temperature is conventionally known, martensite and bainite will be generated. In this case, even if the temperature drops to below 90℃, which would otherwise pose a risk of overcooling, there is no formation of supercooled structures at all, and furthermore, the patenting process can be safely performed up to a much lower temperature of nearly 70℃, and the resulting direct patenting process The present invention was made based on the discovery that the tensile strength of the wire can be on the same level as lead patenting. According to experiments conducted by the present inventors, even if the temperature is the same, the state of oxidized scale on the surface of the treated wire is clearly different when air is blown into hot water and when it is not. This is considered to be advantageous in suppressing the occurrence of boiling. In other words, it is assumed that film boiling is stabilized by phenomena such as air bubbles stabilizing film boiling, or air bubbles destroying locally generated nucleate boiling, and therefore even in hot water in a significantly subcooled state. It is thought that there is no generation of martensite or bainite, that is, it becomes difficult to cause quenching.
This discovery is an important basis for the present invention. Generally, when air is blown into hot water close to its boiling point, the rate at which the temperature of the hot water decreases is related to the water temperature, the amount of air blown into the hot water per unit volume per unit time, the temperature and humidity of the air, the size of bubbles, etc. These points will be explained in detail below. As shown by curve a in FIG. 2, the saturation pressure of water vapor increases rapidly with temperature. Therefore, air is saturated with water vapor at room temperature (at room temperature, the vapor pressure of water vapor is low, so the amount of water vapor it contains can be considered almost zero).
When the air in the air bubbles formed at the bottom of the hot water rises through the hot water, it rapidly becomes air containing water vapor up to the saturation pressure of the hot water temperature due to the evaporation of water from the surrounding hot water. Expands rapidly in volume. As shown in curve b in Figure 2, the volume is approximately 1.2 times larger when the water temperature is 60°C, but it is 2.4 times larger when the water temperature is 80°C.
4.3 times at 90℃, and about 7.3 times at 95℃. That is, this phenomenon removes the heat of evaporation from the hot water, and when the temperature of the hot water is high and approaches the boiling point, the heat removal and cooling effects due to air blowing rapidly increase.
For example, when air at a temperature of 30°C and relative humidity of 60% is blown into warm water at a temperature of 90°C, a maximum of approximately 0.9 Kcal of heat is removed per air. Of course, in this case, the smaller the air bubbles, the larger the evaporation specific surface area, and the air in the bubbles is quickly saturated with water vapor until the bubbles float to the surface of the hot water, so the heat removal per unit air blowing amount is large. Therefore, in practice, providing a device to make the air bubbles smaller will improve the heat removal efficiency. Therefore, it is recommended to change the hole diameter and shape of the blowing nozzle, or to install a rotating propeller in the upward path of the bubbles to cut the bubbles into fine nuclei. Furthermore, since the air bubbles rise vertically in the hot water and are absorbed and stirred in the rising path, there is an advantage that only the rising portion of the air bubbles in the hot water is locally cooled and stirred. Figure 3 shows the results of an experiment using a beaker.When air is blown into hot water from the lower part, it cools rapidly from 100℃ to about 80℃, but as the temperature of the water decreases, the cooling rate decreases, and below 70℃, air is blown in. It can be seen that the influence of Figure 4 shows the amount of air and water temperature when air saturated with water vapor at room temperature (20°C) is blown into hot water at about 100°C (in this case, the amount of water vapor contained is very small and not a problem). This figure shows the relationship between the cooling rate of It can be seen from this graph that by controlling the amount of air, the cooling rate (heat removal amount) of hot water at a certain hot water temperature can be controlled. Therefore, for example, due to the heat input of the wire, the temperature of hot water is 0.15
When the temperature rises at a rate of °C/sec, as shown by curve 4 in Figure 4, if air is blown at a rate of 0.076/sec per 1 volume of hot water, the temperature of the hot water stabilizes at 95 °C, and the patenting process can be performed at that temperature. Furthermore, per amount of hot water
90℃ for air flow rate of 0.17/sec, 80℃ for 0.44/sec
℃ and 0.89/sec, it is possible to perform the patenting process while maintaining the hot water temperature at 70℃. On the other hand, the cooling rate of hot water, that is, the amount of heat removed from hot water, can be easily adjusted by appropriately mixing water vapor of 100℃ or higher from a boiler, etc. with air to create air at a desired temperature and humidity, and then blowing it into hot water. can do. For example, if air containing saturated steam is blown at 90°C, the bubbles will hardly expand even if the temperature of the hot water is 95°C, and the cooling rate of the hot water will be very slow. Furthermore, when the temperature of the hot water is 95°C, the bubbles do not expand and there is no evaporation of water vapor, so there is almost no heat removal effect and only a stirring effect. Furthermore, when hot water is blown into hot water below 90℃, the hot water is heated. When air is blown into hot water, the air bubbles that rise cause the hot water to become highly agitated. The size of this stirring is the size of the air bubbles relative to the horizontal cross-sectional area of the hot water at that location, that is, the amount of air blown against the surface area of the hot water is converted to the volume of steam-saturated air at the same temperature as the water temperature. It is indicated by the value. According to experiments conducted by the inventors, high-temperature 11mmφ wire rods
When immersed in hot water of 95℃ to 70℃ and subjected to patenting treatment, a martensite structure was generated in normal hot water, but when the above converted amount of air was blown for more than 30 / m ² seconds from the bottom of the hot water tank. In this case, a wire rod with tensile strength equivalent to that of lead patenting was obtained without the generation of martensitic structure. In a direct patenting device, for example, as shown in FIG. 1, a wire is spirally formed into a ring,
When this is placed on a conveyor in a non-concentric state approximately horizontally and transported in hot water, or when the loose spiral coil is stretched in the direction of travel so that it becomes a nearly vertical ring shape. When transferring the wire rod while suspended in a hot water tank, etc., if the ring is divided equally in the width direction on the plane formed by the traveling direction of the wire being transferred and the rising direction of the air bubbles, the amount of wire rod divided will be larger at the edges. , the distribution is such that it is minimum in the center. Therefore, the heat input by the wire is maximum at the edges and less at the center, and in reality this ratio reaches 3 to 4 times, although it is not as theoretical as the wire may meander. Therefore, it is desirable for the device of the present invention to have a structure in which many air bubbles are concentrated at the edges of the wire. Further, when the spiral wire ring is cooled while moving laterally in hot water, the conditions of the air blown into it can be changed appropriately in the length direction of the movement. It is also possible to provide a section during the transfer in which air is not blown. In this way, it is possible to provide an arbitrary temperature gradient in the cooling of the wire in the length direction and a gradient or change in the stirring intensity of the hot water. Further, in the present invention, heat is removed from the hot water mainly by blowing air, but an auxiliary cooling means or a heating means may be used in combination if necessary. That is, when the water temperature is around 70°C, the saturated vapor pressure of water becomes low, so it is necessary to blow in a significantly large amount of air to cool the water to below this temperature. Also, the temperature of the hot water
Even when the temperature is 70°C or higher, as the amount of wire rods processed in the hot water tank increases, the temperature of the hot water increases due to heat input from the wire rods, so a large amount of air is required to be blown into the tank. In this case, it may be advantageous to use an auxiliary hot water cooling method. Even in that case, since the temperature of the hot water is high, there is an advantage that the heat exchange device can be small-scale. On the other hand, if the heat input from the wire is small and the water temperature drops below the specified temperature when blowing air to obtain the necessary stirring strength, use an auxiliary heating method such as blowing superheated steam. Alternatively, the temperature and humidity of the blown air may be adjusted to obtain the necessary heat removal effect and the necessary stirring effect. The present invention will be explained in more detail below using examples. Example 1 Using a hot water bath, a test piece of 11 mmφ high carbon steel wire rod of 0.8C and 0.68Mn was immersed in hot water for patenting treatment, and at the same time, the temperature of the hot water was changed and air was blown. We compared cases with and without.
The results were as shown in FIG. In other words, even without air blowing, an increase in tensile strength is observed as the hot water temperature decreases, but when the hot water temperature drops below approximately 90°C, supercooled structures (martensite, etc.) are formed as shown by the x mark in the figure. In that case, the tensile strength will be significantly reduced. In other words, if the water temperature is below 90°C, there is a risk of overcooled tissue forming. However, when air is blown into the water and stirred, the tensile strength increases as the water temperature decreases, and the rate of increase is approximately twice that of the case without air blowing, and when the water temperature is around 80°C, the tensile strength becomes equivalent to that of lead patenting. Furthermore, even when the water temperature was lowered to nearly 70°C, stable patenting processing was possible with no generation of overcooled structures. Example 2 The same wire rod as in Example 1 was blown with air to maintain the hot water temperature at 78±2° C., and the amount of air blown was varied as shown in FIG. 6. The results were as shown in FIG. In other words, as the amount of air blown increases, the tensile strength also increases, and the tensile strength increases ^by 15/sec (converted to 33
/sec) The increase becomes more noticeable from the vicinity, and when it exceeds 20/sec (converted to 44/sec), it can be seen that the same level of tensile strength as lead patenting can be obtained. Example 3 Using the apparatus shown in Fig. 7 described later, the temperature was 0.8°C,
0.68Mn high carbon steel was rolled into a 10mmφ wire rod with a unit weight of 400Kg and directly patented. The conditions at that time are as follows. (b) Water temperature 83℃, air blowing amount 6m ³ /min m ³ (hot water),
Stirring strength with air is 80/sec. m ² (conversion 220
/second. m ² hot water surface) (b) Water temperature 90℃, air blowing amount 3.6 m ³ /min m ³
(hot water), air stirring strength 48/sec ^m2 (conversion
200/sec. m ² hot water level) In both cases, supplementary cooling was not performed, but
No substantial change in hot water temperature was observed during the treatment period. The immersion time in warm water was 50 seconds. For comparison, wire rods with the same components were processed under the following conditions without air blowing. (c) Immersed in warm water with a water temperature of 83°C. In that case, after processing one bundle of wire, the temperature of the water was 87°C. (d) Immersion treatment was carried out at a water temperature of approximately 100°C, that is, near the boiling point. Of course, there is no change in the water temperature. The 10 mmφ wire processed under the above conditions was finished at a finishing speed of 145 using a non-slip 8-stage continuous wire drawing machine.
A wire drawing test was conducted in which the wire was drawn up to 4.0φ (workability: 84%) at m/min. The results were as follows.

[Table] That is, the wire made by the method of the present invention in (a) and (b) is
(d) Tensile strength is about 5 to 50% higher than that of conventional wire
The wire was drawn at a rate of 10Kg/ ^mm2 without any problems. However, the wire rod immersed in hot water at 83° C. without air blowing in (c) was partially burnt, and as a result, the wire broke during wire drawing and could not be processed into wire. Embodiment 4 FIG. 7 shows an example of an apparatus for implementing the present invention. Finish rolling stand 1 as shown in the figure
The high-temperature wire rod 1 that has been finish-rolled in step 3 is formed into a ring shape and wound by a laying type winder 2. A hot water tank 4 is provided below the winder 2, and the inside thereof is filled with hot water 3. Directly below the winder 2, there is a horizontal conveyor 10 in warm water.
Following the conveyor 10, an inclined conveyor 11 is provided to guide the wire above the upper surface of the hot water, and further to transport the wire by means of a horizontal discharge conveyor 12. An air chamber 5 is provided below the horizontal conveyor 10, and the air chamber 5 has a pipe 8 having a pressure gauge 7 and a valve 6, and compressed air is introduced from the outside into the air chamber while being controlled. An air blowing hole 9 is provided in the upper surface of the air chamber 5, so that air is blown out into the hot water. The high-temperature wire rod is formed into a ring shape by a winder, becomes a spiral shape, and falls into hot water, and is transferred onto a horizontal conveyor 10 as a wire rod 14 in which the rings are arranged in a slightly shifted shape. , are carried out from the inclined conveyor 11 by the carry-out conveyor 12. Falling into warm water, or horizontal conveyor 10 and inclined conveyor 11
While moving, the wire is cooled by hot water that is stirred by the air blown from the air blowing hole 9. This is how the method of the invention is carried out. Embodiment 5 FIG. 8 shows another embodiment. Basically, the device is the same as in Example 4, but the wire rod that has been made into a ring shape by the winder 2 is dropped onto a horizontal preliminary conveyor 15, and after being preliminary cooled in the atmosphere. It falls onto a horizontal conveyor 10 provided in the hot water tank 4. On the other hand, four sets of air pipes 8, 8', . . . are provided below the horizontal conveyor 10, and the amount of air can be controlled by valves 6, 6', . Air passes through piping 8 and is blown out from an outlet 16 into the hot water. Further, a steam pipe 21 from a boiler is connected to each air pipe 8, 8', . . . through a control valve 22. Furthermore, in this device, as shown in the A-A cross-sectional view in Fig. 9, the ring-shaped wire 14 is placed on the horizontal conveyor 10 in hot water and is transferred, so that it is transferred in the same direction as the horizontal conveyor. Branch pipes extend from the air pipe 8 in the right angle direction, that is, in the lateral direction, and are provided with air branch pipes 17 having air outlet ports 16 densely arranged at the edges of the ring and sparsely arranged at the center. This provides greater agitation to the edges of the ring than to the center. Furthermore, this effect can be enhanced by attaching a bubble inner plate 18 so that the bubbles are concentrated at the edges. Moreover, this allows a large amount of heat to be removed from the hot water portion where the heat input from the wire is large. In this case, the piping for the edge and the center may be separate systems. According to this device, by adjusting the control valve 22, the temperature of hot water can be controlled by mixing an appropriate amount of steam with the blown air to control the amount of heat removed. Generally, the temperature and stirring intensity of hot water can be controlled by controlling the amount of air using the valve 6, controlling the amount of water vapor using the control valve 22, or by using both. However, in reality, it is convenient to control the temperature based on the amount of water vapor, and the temperature of the hot water can also be automatically controlled using the control valve 22. For example, if the continuous dipping of the wire is interrupted due to a failure of the rolling mill, a large amount of steam can be supplied to maintain the temperature of the hot water at a predetermined temperature. With this device, it is possible to apply stronger agitation to the edge of the wire rod being transferred, and to provide an appropriate bubble intensity distribution and temperature distribution to the cooling rate in the transfer direction, making it possible to accurately carry out the method of the present invention. . Embodiment 6 FIG. 10 shows still another embodiment of the present invention. In this case, a hot water tank 4 having air piping similar to that shown in FIG. , and falls into the hot water 3 in a spiral shape. A hook conveyor 19 having a substantially horizontal transfer section is provided in hot water, and the falling spiral wire is successively suspended from the hook 20 of the conveyor 19 ring by ring.
It is designed to be cooled by moving horizontally in warm water. In this way, the wire rings can be cooled uniformly in the hot water and transferred horizontally without overlapping. The cooled wire rod is carried out by an inclined conveyor 11 and a carry-out conveyor 12. The present apparatus can also effectively heat-treat steel wire rods. The present invention has been described above using examples, but as is clear from the above description, the present invention is applicable to hot water being a solution,
A suspension or the like may be used, and other gases may be used instead of air. In addition, an auxiliary hot water heating or cooling device may be attached to the hot water tank, or new cold water may be added to assist in regulating the temperature of the hot water. Furthermore, it is also possible to attach an apparatus for pre-cooling the wire rod before processing it with the apparatus of the present invention, or for post-processing the wire rod after leaving the hot water tank depending on the purpose. F. Effects of the Invention As explained in detail above, the present invention provides a direct patenting method for medium-high carbon steel wire rods in which a high-temperature wire rod is immersed in hot water for heat treatment. By adjusting the amount of gas and the mixing ratio, the hot water temperature can be set to an arbitrary sub-cooled state (temperature below the boiling point), while still being strongly stirred by air blowing.The high-temperature medium-high carbon steel wire rod immediately after rolling is placed in hot water. A direct patenting method and device characterized by immersing and cooling, the equipment cost and operating cost are low,
Moreover, the present invention provides an effective direct patenting method and apparatus for medium-to-high carbon steel wires, which can produce good direct patenting wires with high tensile strength without producing an overcooled structure in thick wires.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional direct patenting device using hot water, Figure 2 is a graph showing the relationship between water vapor saturation pressure and bubble expansion rate with temperature, Figures 3 and 4.
The figure is a graph showing a cooling curve and cooling rate when air is blown into hot water. 5 and 6 are charts showing the results of implementing the method of the present invention, FIG. 7 shows an example of an air blowing direct patenting device, and FIGS. 8 and 10 are diagrams showing the results of implementing the method of the present invention. FIG. 9 is a sectional view taken along the line AA of FIG. 8. FIG. 1, 14: Wire rod, 2: Laying type winder, 3:
Hot water, 4: Hot water tank, 5: Air chamber, 6, 6', 6'',
6: Valve, 7: Pressure gauge, 8, 8', 8'', 8
: Air piping, 9: Air outlet, 10: Horizontal conveyor, 11: Inclined conveyor, 12: Unloading conveyor, 13: Finish rolling mill, 14: Ring-shaped wire rod, 15: Pre-cooling conveyor, 16:
Air outlet, 17: Air branch pipe, 18: Guide plate, 19: Hook conveyor, 20: Hook,
21, 21', 21'', 21: Steam piping, 2
2, 22', 22'', 22: Control valve, 23, 23', 23'', 23: Compressed air piping.

Claims (1)

[Claims] 1. Hot-rolled high-temperature medium-high carbon steel wire rod is continuously formed into a ring shape, and the ring is spirally dropped into hot water and expanded into a continuous ring shape. In a heat treatment method in which the wire ring is cooled to transform into a pearlite structure by passing through the hot water, air is blown into the hot water from below the wire ring being immersed in the entire cooling section or a partial section thereof, and,
Adjust the density of the fine bubbles of the blown air at the edge of the steel wire continuous ring to be 3 to 4 times that at the center, and the overall amount of air is 60 to 95 times the density of the hot water.
A direct patenting method for medium-high carbon steel wire, characterized by adjusting the temperature to a predetermined temperature of °C. 2. A medium-high carbon steel wire rod according to claim 1, characterized in that a heat exchanger is attached to the hot water tank to circulate hot water or to supplementally control the hot water temperature by replenishing cold water. Direct patenting method. 3. The medium-high carbon steel wire rod according to claim 1 or ² , characterized in that an air volume of 30/sec or more is blown into the portion of the wire rod immersed in hot water per 1 m 2 of planar area of the hot water tank. Direct patenting method. 4. A direct patenting method for medium-high carbon steel wire according to any one of claims 1 to 3, characterized in that a thick wire with a diameter of 8 mmφ or more is heat treated. 5 A device for forming a rolled high-temperature medium-high carbon steel wire rod into a ring shape, a hot water tank for cooling the wire rod, and one or more devices for transferring the wire rod formed into a ring shape into hot water and taking it out from the hot water tank. An air blowing device is provided below the wire being transferred in hot water, and the amount of air blown is larger at the edges of the wire and less at the center in a direction perpendicular to the direction of movement of the wire being transferred in the hot water tank. A device is provided for controlling the amount and conditions of air blowing for each section, by providing blow holes or blowing ports with a sparse and dense distribution so as to divide the direction of movement of the wire being transferred in the hot water, and by providing a device for controlling the amount and conditions of air blowing for each section. This is a direct patenting device for medium-high carbon steel wire rods, which is characterized by blowing in air. 6. Direct patenting of medium-high carbon steel wire according to claim 5, characterized in that a guide plate is provided in the hot water tank so that bubbles caused by blown air concentrate at a predetermined location in the tank and rise. Device. 7. A medium-high carbon steel wire rod according to any one of claims 5 to 6, characterized in that the wire rod is cooled while controlling the temperature of the hot water by adding an auxiliary means for cooling or heating the hot water. direct patenting equipment. 8. According to any one of claims 5 to 7, the hot water tank is provided with auxiliary cooling water as external or circulating water, and piping is provided to particularly cool the hot water at the edge of the wire rod. Direct patenting equipment for medium-high carbon steel wire. 9. A direct patenting device for medium-high carbon steel wire according to any one of claims 5 to 8, characterized in that a pre-cooling device for the wire is provided between the winding machine and the hot water tank.