KR100530331B1 - Method for manufacturing high-carbon steel wire with uniform cooling effect - Google Patents

Abstract

The present invention relates to a high-carbon steel wire uniform cooling manufacturing method that can be used to improve the quality of the wire rod by using the Stelmore cooling equipment and minimizing the occurrence of cooling of the wire coils in the high carbon steel wire rod manufacturing process.

The present invention in the manufacture of high-carbon steel wire rod for forced cooling by air while dropping the wire rod hot rolled billet hot rolling constant rolling through a continuous rolling mill in the form of concentric coiling by a winding machine Adjusting the composition of the billet by weight% to C: 0.69 to 0.76, Si: 0.15 to 0.35, Mn: 0.30 to 0.60, P: 0.03, S: 0.03 or less, residual Fe and unavoidable impurities; Rolling the billet by wire and cooling it to a temperature of 850 to 800 ° C. before winding; After winding, in order to properly disperse the overlapping density of wire rod coils, round bar-shaped bars are attached to the circumferential surface of some of the wire stelmore conveyor rollers to form a lip roller, and the wire coil is forced to be transported thereon and cooled. It provides a high carbon steel wire rod uniform cooling manufacturing method comprising a.

Description

High Carbon Steel Wire Rod Uniform Cooling Manufacturing Method {METHOD FOR MANUFACTURING HIGH-CARBON STEEL WIRE WITH UNIFORM COOLING EFFECT}

The present invention is a cooling and cooling equipment in the form of a non-concentric ring by winding the small-size wire made of the final product after the high temperature reduction through a continuous rolling mill to heat the billet (Billet) to a constant temperature and hot rolled to an appropriate diameter The present invention relates to a method for obtaining a wire rod product having a uniform structure by cooling by a forced air cooling device during dropping on a conveyor of a Stelmor cooling facility and transporting it in a stacked state. More specifically, a circular conveyor roller By welding a small diameter steel bar on the surface, wire rod coil density generated by wire rod overlap density difference of circular coil shape is distributed during cooling of wire rod by table roller driving, thereby reducing the variation of cooling temperature to produce wire rod of uniform quality. It is about a method.

As a facility to which the present invention relates, the method of cooling the wire rod by the Stelmore cooling controller can be described with reference to FIGS. 1 and 2. As shown here, the wire rod manufactured by passing the billet through the heating furnace 1, the bath, the intermediate rolling mill 3, the water cooling device 3, the finishing mill 4, and the water cooling device 5 in turn is wound up (6). And through the Stelmore cooling section (6) is continuously dropped in the form of a concentric ring on the Stelmore cooling conveyor is transported by the table roller (7) in a state of being stacked. The hot wire thus transferred is subjected to a cooling effect by the forced blow of the blower 10 installed below the table roller 7 to secure mechanical properties of the final product desired by the demand.

This cooling is called Stelmore cooling, and the basic principle of cooling is shown in FIG. When the rolled hot wire 11 is dropped from the laying head of the winder to a coil-ring form from a straight line to the roller 7, the blower 10 is installed in the blower 10 installed under the Stelmore cooling device. Forced blown air is supplied to the wire rod through the duct 9 to be cooled. At this time, the high-temperature wire dropped from the laying head of the winding machine in the form of a ring is a ring-shaped concentric circle of about 1070mm in diameter, so it is continuously falling and transported, so that the overlapping density between the wire coils is relatively high and the overlapping density is relatively low. Inevitably, in this state, even if forced air blowing cooling is performed, unavoidable cooling variations occurring in the overlapping density difference of the wire rod coil are inevitable. In addition, the recent demand for high-carbon steel wire rod products is the trend of commercialization of products with high strength and high toughness mechanical properties. The production of products accompanied by the omission of the heat treatment process, the lead patenting process, has been attempted around the advanced wire rod plant since 80 years. To make these products, homogenization of the tissue is essential during material cooling. This is because the occurrence of cooling temperature and tensile strength deviation caused by overlap density difference during cooling by forced blowing air causes problems such as disconnection in the subsequent processing.

Therefore, in this field, efforts have been made to minimize the variation in tensile strength during wire rod cooling, and commercialization of a product that omits lead patenting heat treatment, which is substantially uniform product and demand side first heat treatment process, has been attempted. It became.

Some representative examples of efforts to minimize the variation in tensile strength of such wire products include, first of all, the cooling method developed by Kobe Steel Works in Japan. This cooling method improves the size and direction of air slit through which forced blowing air is discharged in the Stelmore cooling process, which is a wire rod cooling process. Even though the air flows from the blower by biasing towards the edge part where a lot of gas is generated, the cooling of the edge part proceeds a lot, and the cooling speed with the center part is controlled similarly, and the tensile strength deviation value is 1.0kg / mm2 or less (coil In-ring deviation). However, in this case, since the inevitable retrofitting of the existing Stelmore nozzle, the initial equipment investment costs are high.

Second, there is a device with multiple side guide rollers developed by the US Morgan Morgan to reduce the cooling temperature variation by artificial meander induction of the wire coil. This device installs a unit device consisting of side guide rollers 13 as shown in Fig. 6 on the Stelmore side wall in a constant length symmetrical direction to remind the coils when the wire coil is transported on the Stelmore table roller. It is a device to induce cooling uniformly by spreading the progress of the wire coil to the left and right by forcibly contacting the rollers 13 and widening the gap between the wire rod coils and the density of the edge where the overlapping density is relatively high. . However, even in this case, there may be a slight effect in reducing the deviation, but when used for a long time, contact between the side guide roller 13 and the wire coil 11 causes frequent contact wear and scratches on the body and the wire coil. The situation is avoiding use.

Therefore, the present invention has been studied to solve the above conventional problems, wire rod which is transferred to the Stelmore table roller during the manufacture of high carbon steel wire having a high carbon content as one of the high-grade steel wire produced in the wire rod factory Wire rods with appropriate dimensions of circular bars are attached from both sides of the upper and lower wire rod overlap densities of relatively high distances from both sides of the table rollers, and the wire coils are rotated by contact with the wire coils. Its purpose is to reduce the cooling temperature variation and the tensile strength variation of the edge and center of the wire rod by dispersing the overlap density between the coils at the location by applying the force in the direction of dropping them to the overlapping portions of the wire rod. When manufacturing slow cooling material to obtain low tensile strength deviation value by cooling most slowly in air cooling state There is also an excellent effect.

Hereinafter, with reference to the accompanying drawings, the present invention for achieving the above object will be described in more detail.

According to the present invention, as shown in FIG. 3, a lip roller 12 having a diameter of about 5.5 to 13.0 mm∮ and a length of about 300 mm attached to the roller outer circumferential surface in the roller length direction is used for conveying the wire to be cooled. . Such a roller attached to the bar configuration is called a ribbed roller (Ribbed Roller) for convenience, such a rip roller can be configured by attaching the bar to the 300mm point inward from the point about 90mm away from both sides of the existing stealmore table roller. In order to examine the overlapping density and spacing of the edge portion of the wire coil according to the contact between the wire coil and the lip roller, two pieces at 180 degree intervals as shown in FIG. 3B based on the total circumferential angle 360 degrees of the circular roller body, The actual field test was conducted by installing three bars at intervals of 120 degrees and four bars at intervals of 90 degrees.

Figure 7 is a schematic front view showing an installation use example of the rip rollers installed in the field and actually tested.

In the case of the existing method used to reduce the tensile strength variation caused by the overlap density difference of the wire coil in the Stelmore cooling method, the direction of the coil and the overlap of the coil are first made by using artificial friction force during the progress of the wire coil. As described above, the density of the side guide rollers is frequently avoided due to the occurrence of material scratches in the case of the multi-side guide roller due to the problem of facility structure. In the case of the cooling method, there is a problem in that the entire Stallmore section where the cooling takes place has to be renovated at a high cost.

On the contrary, in the case of the present invention, by simply welding and attaching the bar of the above specification to the surface of some of the existing Stelmore table rollers, the overlapping density between the desired wire coils can be efficiently dispersed. It can be explained.

In the present invention, as the diameter of the lip roller installed on the top of the Stelmore table increases, the wire coil overlap density dispersion effect can be increased due to the increase in the contact area and the momentum with the wire rod coil, When the table roller is rotated due to the refractory and the nozzle slit configuration, problems with contact with the refractory on the lower part of the roller or a poor rotation may occur, so it is necessary to limit the diameter of the lip roller to about 13.0 mm∮ or less.

The length of the length of the table roller of the wire rod stealmore cooling facility currently used is 1250mm, and the position where the wire rod coil has the highest overlap density when transferring the wire coil using these rollers is located within about 200mm from the coil end. It becomes the site of. In addition, if the diameter of the wire coil reaches an average of about 1070 mm, assuming that the center feed from the top of the Stelmore table roller, the bar is installed in the above positions of both side of the table roller, the tensile strength deviation and cooling under actual operating conditions Application tests of temperature deviation reduction were conducted.

At this time, the initial attachment position of the steel bar allows about 45 mm from the end of the Stelmore conveyor roller, because the position of both side portions of the table rollers at both ends where the overlap density is relatively high when the wire rod is accurately centered Since it is located about 200-250mm from the upper part, if the bar is installed from the position of about 45mm at the end of the table roller as described above, the bar will be in intensive contact with the part with the highest coil compression density. This is because it is possible to induce a more uniform cooling by dispersing).

The present invention is made of a wire billet is made of a wire rod by performing a constant reduction rolling in the wire rolling mill and wound on the conveyor part of the conveyer on the conveyor of the wire stealmore control cooling device after winding down in the form of concentric coiling in the winding machine laying head. The dispersion effect is obtained by stacking the overlap density of the wire rod coil according to the contact between the above-described ribbed roller and the wire rod coil.

In the present invention, the reason for limiting the diameter of the ribbed roller attached to the Stelmore table roller to 5.5mm-13.0mm∮ is as follows. In other words, the structure of the Stelmore cooling system consists of a table roller for transferring the wire rod coil, an air slit for blowing cooling air between the table rollers, and a fireproof material for suppressing hot deformation of the air slit. If the distance between the roller and the fireproof material is about 15mm and the diameter of the lip roller is set to 13.0mm∮ or more, the contact failure between the fireproof material and the rip roller does not occur and the roller does not rotate smoothly. Since the dispersion effect is not obtained, the diameter of the rip roller is limited as described above.

Referring to FIG. 4, when the lip roller is configured and rotated by installing two bars at 180 degree intervals, three at 120 degree intervals, and four bars at 90 degree intervals, the circumferential surface of the selected roller among the Stellamore table rollers The force (Fr) between the force (Fv) acting as the upper portion of the lip roller and the force (Fh) to advance the wire coil forward when the contact between the concentric coil-shaped wire rod and the lip roller in progress By distributing the contacts between the wire coils at the overlapping portions of the wire coils, it is possible to induce more uniform cooling of the wire coils even under the same amount of airflow conditions.

Table 2 shows the tensile strength values and deviations, which are mechanical properties, under field experimental conditions under these experimental conditions, in comparison with the inventive and comparative materials.

Example

The cast billet for continuous production of the high carbon steel wire (JIS SWRH72A) having the chemical composition shown in Table 1 was hot rolled to a diameter of 5.5mm∮ and then cooled to a cooling start temperature range of 800 ~ 850 ℃. The linear wire rod thus cooled was wound in the form of a concentric continuous coil through a winding machine laying head, and forced cooling was performed under the cooling conditions shown in Table 2 on the cooling table.

At this time, in the case of the present invention as shown in Figure 3 a, b Stolemore table rollers attached to the surface of some of the rollers to form a lip roller and was driven with the other table rollers. In the installation section, five lip rollers were installed in zone # 1, which is a section where transformation occurs rapidly in the beginning. Generally, the transformation starts and ends in Stallmore # 2 zone, which is 21 meters in length, but the reason why the # 1 zone lip roller is installed compared to the 2 zone is when the lip roller is installed in the section where the initial cooling proceeds. This is because there is an advantage that the gap between the wire coiling and the next coiling can be widened rapidly. The reason for this is that in case of # 1 zone where the initial cooling proceeds, the momentum to push in the direction of the wire rod is easily generated even if a slight impact is applied to the overlapping part between the wire coilings using the lip roller. This is because there is an advantage. However, if the rip roller is installed outside the zone # 1, the cooling of the zone will occur to some extent and the strength of the wire structure will be secured to some extent. Since the momentum due to the securing cannot be generated as desired, the installation section of the rip roller was set to the cooling # 1 zone.

In addition, the reason why the installation shape of the rip roller is set as shown in Fig. 3B is as follows. In general, when the straight wire is wound in a circular shape by the winding machine in the final rolling state, the wider the gap between the center of the circular wire rod coil and the center of the next wire rod coil is, the smaller the overlap density between the coils becomes. Not only is the cooling accelerated, but the temperature variation between the wire coilings is also reduced, which is advantageous for securing a wire of uniform material. For reference, the distance between wire coiling by current Stelmore winding machine is about 27mm on average.

Therefore, as a result of introducing the present invention to the rolling and cooling conditions of the Stelmore plant, when the ribbed rollers having two steel bars installed at 180 degree intervals were measured, the distance between the coils of the wire rods was about 37% larger than that of ordinary materials. A 37mm ring-to-ring spacing was obtained, and when the rod-mounted lip rollers with 120 degree intervals were used, the gap of 35mm was about 30% larger than that of the conventional material, and when the rod-mounted lip rollers with 90 degree intervals were used, the 120-degree intervals were almost same as when the rod-mounted lip rollers were used. By showing a similar distance between the coils of wire rods of about 35mm, the overlap density was significantly reduced compared to the conventional common materials, thereby improving cooling performance and securing mechanical properties of more uniform wire products.

Table 2 shows a comparison of the characteristics of the wire rods produced under the cooling conditions according to the present invention with the conventional cooling conditions of the high carbon steel hard steel wire rod having the chemical composition of Table 1. Here, the characteristics of the tensile strength are selected by selecting three random wire coils, reselecting one ring, which is a representative sample for each coil, and dividing the coil into eight equal parts to obtain the average tensile strength and deviation value for each part. It was.

As shown in Table 2, after the lip roller was installed on the Stelmore cooling table roller, the tensile strength deviation and the tensile strength deviation, which are mechanical properties, were compared to those of the Stelmore comparative material. The tensile strength is improved by ~ 21.1% and the tensile strength is about 3.4 ~ 5.6% compared to the comparative material.

fairyland Chemical composition (wt%) Remarks C Si Mn P S 5.5mm∮SWRH72A 0.69 to 0.77 0.15 to 0.35 0.30 to 0.60 0.03 0.03

division Cooling start temperature (℃) Cooling Table Speed (m / s) Use of Lip Roller Tensile strength per wire coil ring (kg / mm2) Remarks (Interval) (mm) value Deviation Invention 1 830 0.75 Use (180 degrees) 110.5 1.21 37 845 0.80 111.1 1.19 835 0.85 112.0 1.23 Invention 2 850 0.80 Usage (120) 109.3 1.27 35 825 0.85 110.1 1.29 835 0.90 109.7 1.30 Invention 3 830 0.80 Use (90 degrees) 109.1 1.30 35 835 0.80 108.9 1.34 840 0.90 109.7 1.27 Invention 4 825 0.85 unused 105.5 1.42 27 835 0.95 106.1 1.51 830 0.90 106.5 1.47

As described above, the present invention is related to the cooling temperature deviation control which directly affects the wire rod product. The lip roller and the wire rod are installed by installing a circular lip roller on the top of the Stelmore table roller that rotates during cooling by the conventional air blowing. By dispersing the contact generated in the wire overlap density difference by the action of the momentum due to the contact between the coils, there is an effect that can effectively reduce the cooling deviation and the tensile strength deviation of the wire.

1 is a configuration diagram of a forced supply cooling facility for cooling hot smoked wire rod;

Figure 2 is a nozzle slitting configuration of the Stelmore cooling device,

3 is a configuration diagram of a ribbed roller, a is a perspective view of the use state of the ribbed roller, b is a front view showing the configuration examples of the ribbed roller;

4 is a schematic diagram in which uniform cooling proceeds according to the present invention;

5 is a cooling temperature distribution chart for each wire part according to the actual field test of the present invention,

Fig. 6 is a perspective view of an essential part of a conventional apparatus provided with a side guide roller;

Figure 7 is a front view showing the configuration of the ribbed roller and the Stelmore cooling device air slits.

Explanation of symbols on main parts of drawing

1: Reheating Furnace 2: Rough Mill

3: water cooling device 4: finishing mill

5: Water Cooling 6: Winding Machine and Stallmore Cooling Section

7: Stelmore Table Roller

8: Stelmore Side Wall

9: Duct 10: Blower Motor

11 wire rod coil 12 Ribbed Roller

Claims (2)

In the manufacture of high-carbon steel wire rod which is forced to cool by air while continuously transporting the wire rod hot rolled billet through a continuous rolling mill in a concentric coiling form by a winding machine in the form of a winding machine, Adjusting the composition of the billet by weight% to C: 0.96 to 0.76, Si: 0.15 to 0.35, Mn: 0.30 to 0.60, P: 0.03, S: 0.03 or less, residual Fe and unavoidable impurities; Rolling the billet and cooling it to a temperature of 850 to 800 ° C. before winding; In order to properly disperse the overlapping density of the wire rod coils after winding, a plurality of bars in the form of a circular bar are attached to the circumferential surface of some of the wire rod stealmore conveyor rollers to form a lip roller, and the wire coil is forced to be transported thereon for cooling. High-carbon steel wire rod uniform cooling manufacturing method comprising the step of. The method for producing a high carbon steel wire uniform cooling according to claim 1, wherein a lip roller is formed by arranging at least two circular steel bars at regular angular intervals along its circumferential direction.