JPH064893B2 - How to cool wire rods and steel bars - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for online cooling of a wire rod or a steel bar.

(Prior Art) For the purpose of improving the quality of wire rods and steel bars and reducing the cost, rapid cooling is performed immediately after hot rolling to improve the strength and toughness by refining the structure.

In addition to the above purpose, in order to further improve productivity,
Immediately after rough rolling, quenching is performed and finish rolling is performed in the two-phase region of ferrite and austenite, and the annealing time is halved and completely omitted.

Although such a cooling device is required to have uniform cooling ability and high cooling ability, in the conventional cooling device, as shown in FIG. 9, a large number of nozzles 12 are provided on the inner surface of the pipe-shaped cooling pipe 11. The cooling water is jetted to the material running inside the cooling pipe 11, and the water surface and the compressed air jetted in the opposite direction to the running direction by the drainage noise 13 installed at the outlet of the cooling pipe 11 The cooling water adhering to the is removed. In addition, 14 in FIG. 9 shows a conveying roller.

However, the cooling device as shown in FIG. 9 has the following problems.

A large amount of cooling water is required for rapid cooling.

Insufficient drainage at the outlet of the cooling device causes large variations in recuperation heat, resulting in significant quality variations.

If the amount of cooling water is increased, the transport resistance of the wire rods and steel bars running in the cooling device increases.

Therefore, as a countermeasure, the following cooling device has been proposed.

(1) As shown in FIG. 10, set the inner diameter of the cooling zone 15 to
The cooling water sprayed on the material from the nozzle 12 provided on the inner surface of the cooling zone 1 is made larger than the diameter of the inlet and the outlet.
The inside of 5 can be filled so that the cooling capacity can be improved by immersion cooling.

(2) As disclosed in Japanese Patent Application Laid-Open No. 59-226121, the cooling water sprayed from the nozzle is drained by arranging it toward the inside of the cooling nozzle on the outlet side (opposite to the material conveying direction). In addition to having a drainage hole in the upper part of the central part of the cooling device to actively drain water, the amount of water flowing out from the cooling device outlet is reduced and the draining effect is enhanced.

(3) As disclosed in JP-A No. 53-127314, a carrier resistance is lowered by injecting a mixture of water and air as a cooling medium into a material.

(Problems to be Solved by the Invention) However, the cooling device described above still has the following problems.

(1) When the inner diameter of the cooling zone is made larger than the diameters of the inlet and the outlet, and the inside of the cooling zone is filled with cooling water and immersion cooling is performed, air remains inside the cooling device and the cooling ability decreases, Non-uniform cooling occurs. Further, in the conventional drill hole nozzle or slit nozzle, the force of penetrating the inside of the cooling device filled with the injected cooling water and the force of stirring the cooling water are small, and the cooling ability is lowered.

(2) Even if the outlet cooling nozzle has a water draining capability, if the water is not sufficiently drained, it will be pulled by the running material and run as water from the outlet, running on the surface of the material and causing uneven cooling.

A cooling device in which a drainage hole is provided in the lower part of the central part is also proposed, but the flow of cooling water in the cooling device is biased to the lower part, and uneven cooling occurs in the upper and lower parts of the steel material.

(3) When a mixture of cooling water and air is used as the cooling medium, residual air causes a large decrease in cooling capacity, resulting in insufficient quality improvement and productivity improvement.

The present invention has been made to solve the above-mentioned problems, and an improved cooling method, an improved uniform cooling property, an improved drainage performance at an outlet of a cooling device, and a cooling method capable of solving various problems caused thereby. It is intended to be provided.

(Means for Solving the Problems) In order to achieve the above object, the cooling method of the present invention is a method of online heating a running high temperature wire rod / steel bar, which is formed in three zones of an inlet, an intermediate and an outlet. In addition, two or more drainage pipes with adjustable drainage amount are provided at the opposite positions in the intermediate zone, and there are many nozzles with adjustable feedwater amount in the inlet and outlet zones in the circumferential direction and the running direction of the wire rod and steel bar. Using the arranged tubular cooling device, cooling in the inlet zone is performed at a high pressure and a high water amount, while cooling in the outlet zone is performed by reducing the flow rate, and from each of the discharge pipes described above in accordance with these total cooling water amounts. The outflow rate is to be adjusted to be uniform.

That is, since the cooling method according to the present invention uses a device in which two or more drainage pipes whose flow rates can be adjusted are provided at opposing positions in the intermediate zone, the discharge flowrates from the respective drainage pipes are made uniform according to the total amount of cooling water. By doing so, the flow in the cooling device is also made uniform in the vertical and horizontal directions, and the wire rod and steel bar can be cooled uniformly in the circumferential direction.

Also, by adjusting the number of drainage pipes to be used and the discharge flow rate according to the total amount of cooling water, the air in the cooling device can be quickly released.

In addition, since the surface temperature of the wire rod and steel bar is below 500 ° C on the outlet side, the heat transfer rate is high and strong cooling is possible even at low pressure.Therefore, the inlet cooling zone performs strong cooling with high pressure and high water flow rate. In the cooling zone, strong cooling can be performed efficiently by reducing the flow rate. Further, by doing so, the outflow amount of the cooling water from the outlet can be narrowed and the outflow pressure can be reduced, so that water rods on the wire rod and the steel bar are almost eliminated, and the draining efficiency can be greatly improved.

Further, if the nozzle proposed by the present applicant in the specification of Japanese Utility Model Application No. 63-32116 is adopted as a large number of nozzles provided in the inlet and outlet cooling zones, the cooling ability is further improved.

(Operation) In the inlet cooling zone of the apparatus used in the cooling method of the present invention, the conveyed wire rod and steel bar are rapidly cooled with a high water density. Further, in the present invention, the flow control valve of the drainage pipe is adjusted according to the total amount of cooling water to discharge at a uniform flow rate from each drainage pipe, so the air remaining in the cooling device easily and completely flows out. To be made. Further, the cooling water ejected from a large number of cooling nozzles provided on the inner surface of the cooling zone forms a uniform flow in the vertical and horizontal directions and flows out from the drain pipe in the intermediate zone. Therefore, the wire rod and the steel bar are uniformly cooled in the circumferential direction.

In the inlet cooling zone, because the film is in a boiling state, it is necessary to have enough water pressure to break the vapor film, so high water density strong cooling is performed.
In the outlet cooling zone, the surface temperature of the wire rod and steel bar to be cooled is low, so the surface is in the nucleate boiling state, so even with a low water density, a large heat transfer coefficient (5000 kcal / m ² ·
h · ° C.), and strong cooling is possible. Therefore, by cooling the amount of water supplied to the outlet cooling zone to be much smaller than that of the inlet cooling zone, the amount of cooling water that flows out from the cooling outlet and adheres to the running wire rod and bar steel and causes uneven cooling can be reduced. Can be lowered. Further, it is necessary to control the amount of water supply and the amount of drainage by a flow rate adjusting mechanism such as an electromagnetic flow valve according to the diameter, material, speed, water temperature, target cooling stop temperature of the wire rod and steel bar.

Further, if the nozzle proposed by the applicant in the specification of Japanese Patent Application No. 63-32116 is adopted for the nozzles installed in the inlet and outlet cooling zones, a larger cooling capacity can be obtained as compared with the drill hole nozzle and the slit nozzle. Further, since the nozzle diameter is larger than the slit nozzle of 2 to 3 mm or the full cone nozzle (foreign matter passage diameter of about 5 mm), the nozzle clogging is small (about 7 mm for a nozzle that obtains the same water amount density), which is advantageous.

(Embodiment) An embodiment drawing and a fourth embodiment showing the present invention in FIGS.
It demonstrates based on drawing which shows the experimental result shown in FIGS.

FIG. 1 is a schematic explanatory view showing an embodiment of a first device used in the method of the present invention in cross section, FIG. 2 is a schematic explanatory view showing an embodiment of the second device in cross section, and FIG. III-I in Figure 2
It is a II sectional view.

In these drawings, 1 is a tubular cooling device used in the method of the present invention, and axially forms three zones 2-4 of an inlet, a middle and an outlet.

Of these, in the intermediate zone 3, for example, four drain pipes 5 are provided at opposing positions, and a large number of nozzles 6 provided in the inlet zone 2 and the outlet zone 4 are sprayed toward, for example, a wire rod 7 and attached to the wire rod 7. The amount of water flowing out is reduced to improve drainage efficiency, and the drainage after cooling the wire 7 can be efficiently discharged from the drainage pipe 5.
A flow rate adjusting valve 8 is provided in the drain pipe 5 so that the discharge amount can be adjusted.

Further, the drain pipe 5 is also provided in the water supply pipe 9 for supplying the cooling water to the many nozzles 6 provided in the inlet zone 2 and the outlet zone 4.
Similarly to the above, a valve 10 whose flow rate is adjustable is provided so that the injection amount of cooling water from the nozzle 6 can be adjusted.

By the way, in the embodiment shown in FIG. 1, the inner diameters of the inlet and outlet of the cooling device 1 and the three zones 2 to 4 of the inlet, the middle and the outlet are the same, but the outlet is long. This is to increase the water flow resistance, prevent the cooling water from flowing out from the cooling device outlet, and prevent the occurrence of uneven cooling on the surface of the wire. Further, in the embodiment shown in FIG. 2, the inner diameters of the three zones 2 to 4 of the inlet, the intermediate and the outlet are set to be larger than the diameters of the inlet and the outlet, and the inside is filled with cooling water and immersed by vigorous stirring and cooling. It is designed to improve the cooling rate.

Further, in the embodiment shown in FIGS. 1 and 2, the nozzles 6 installed in the inlet and outlet zones 2 and 4 are oriented so that their injection angles are toward the intermediate zone 3.

In the embodiment shown in FIG. 2, of the inlet and outlet zones 2 and 4, the nozzle 6 on the inlet and outlet sides is the nozzle 6'proposed by the applicant in the specification of Japanese Patent Application No. 63-32116. The nozzle 6 on the intermediate zone 3 side is a drill hole nozzle.

Next, a method of cooling the wire rod by the method of the present invention using the cooling device 1 having the above-described configuration will be described.

The wire rod is carried in from the left side in the drawing, and in the inlet cooling zone 2, it is strongly cooled by the cooling water ejected from a large number of nozzles 6 ′ (inward) directed in the traveling direction and the drill hole nozzle 6. In the intermediate zone 3, it is cooled by immersion strong stirring, and in the outlet cooling zone 4, it is in the direction opposite to the traveling direction (inward).
It is cooled by the cooling water ejected from the large number of nozzles 6'and the drill hole nozzle 6.

The wire rod thus strongly cooled is carried out from the outlet on the right side of the drawing, but at this time, some cooling water adheres to the surface and flows out. However, since the nozzles 6 and 6'installed in the outlet cooling zone 4 face inward and the amount of water supplied to the outlet cooling zone 4 is small (about 65%), a small amount of draining auxiliary nozzle (not shown, generally). The water can be drained sufficiently with a standard water jet or compressed air nozzle).

Further, in the method of the present invention, since the cooling water is uniformly discharged from the four drain pipes provided on the upper, lower, left and right sides, in the case of water pressure of 2.5 kg / cm ² , the lower drain pipe 5 is The flow rate adjusting valve 8 was narrowed down by about 10 °. In addition, cases ac in the table below
FIG. 4 shows the amount of drainage when the flow rate adjusting valve 8 shown in FIG.

At this time, the inner diameter of the inlet and outlet cooling zones 2 and 4 was increased to about 90 mm with respect to the inlet / outlet diameter of about 50 mm, so that the inside was filled with cooling water and the cooling capacity was improved. By using a part of a larger number of nozzles 6 as the nozzles 6'proposed by the present applicant, the penetrating force is increased as shown in FIG. 5, and the cooling capacity is greatly improved as shown in FIG. .

A large number of nozzles 6 and 6 ′ mounted on the inner surfaces of the cooling zones 2 and 4 are inclined inward at about 45 ° in order to improve the exhaust efficiency and drainage efficiency without lowering the cooling capacity.

As a result of carrying out the method of the present invention using the cooling device having the above-described configuration in an actual machine, as shown in FIGS. 7 and 8, drainage efficiency is improved, compressed air cost is reduced, and cooling water can be effectively used. It became so. Moreover, uniform strong cooling is possible, and the quality defects and shape defects of steel materials are greatly reduced.

(Effects of the Invention) As described above, the present invention enables uniform and strong cooling of steel bars and wire rods, and improves quality and productivity.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing in cross section one embodiment of the first device used in the method of the present invention, and FIG. 2 is a schematic explanatory view showing in cross section one embodiment of the same second device, and FIG. Is III in Fig. 2
-III sectional view, FIG. 4 is a diagram showing the discharge amount when the opening degree of each flow rate adjusting valve is changed, FIG. 5 is a diagram showing the relationship between the collision pressure of various nozzles and the flowing water amount, and FIG. 6 is various The figure which shows the relationship between the average heat transfer coefficient of the nozzle and the steel material temperature, the figure which shows the compressed air utilization rate and the cooling water utilization rate when the device which is used for the method of this invention and the former device in Figure 7 is used, Figure 8 the same FIG. 9 and FIG. 10 showing the defective product generation rate are explanatory views of a conventional cooling device. 1 is a cooling device, 2 is an inlet zone, 3 is an intermediate zone, 4 is an outlet zone, 5 is a drain pipe, 6 and 6'are nozzles, 7 is a wire rod, 8 is a flow control valve, 9 is a water supply pipe, and 10 is a valve. .

Claims (1)

[Claims] 1. A method for online cooling of a running wire / bar steel in a high temperature state, wherein the drain pipe is formed of three zones of an inlet, an intermediate and an outlet, and in the intermediate zone, the drainage amount can be adjusted at a position facing each other. Two or more nozzles are provided, and in the inlet and outlet zones, a tubular cooling device in which a large number of nozzles with adjustable water supply amounts are arranged in the circumferential direction and the running direction of the wire rod and steel bar is used, and cooling in the inlet zone is performed at high pressure. A high amount of water, on the other hand, cooling in the outlet zone is performed by narrowing the flow rate, and the outflow rate from each of the discharge pipes described above is adjusted to be uniform according to the total cooling water volume. Cooling method.