JPS6358207B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an immersion cooling pipe for wire rods and steel bars. As is well known, wire rods manufactured by hot rolling,
A wire material such as a steel bar is cooled from a high temperature immediately after hot rolling to a predetermined temperature in a cooling zone installed after the finish rolling mill row in order to control mechanical properties and suppress scale formation. In such cooling zones, water is usually used as the cooling medium. In this water cooling, it is important to uniformly cool the wire material in its circumference, longitudinal direction, and cross-sectional direction, and to achieve high cooling performance. Improving the cooling capacity has the advantage that the flow rate of cooling water required to obtain a predetermined temperature drop can be reduced, so that the pump power can be reduced. In addition, in continuous hot rolling, in the cooling zone between stands, such as between the intermediate rolling mill row and the finishing rolling mill row,
After cooling water is supplied to the rolled material, controlled rolling is performed in which the material is rolled again by the finishing mill row. Controlled rolling is a hot rolling method in which the heating temperature, rolling temperature, rolling reduction rate, etc. are controlled, and the purpose is to make the crystal grains fine and uniform in the wire material and improve the mechanical properties. In this state, it is possible to produce a wire material having the same structure and mechanical properties as the normalized material. In order to realize this controlled rolling temperature pattern, the inter-stand cooling zone must have as high a cooling capacity (heat transfer coefficient) as possible and a wide control range. Conventionally, various types of cooling zones have been used in the above-mentioned various rolling processes. For example, cooling water is supplied from nozzles (slits) arranged at regular intervals in the circumferential direction of the inner cooling pipe in the direction of movement of the rolled material running along the axial center of the inner layer. There is a spray type that sprays out a spray. With this spray method, the cooling capacity is high in areas where the high-pressure water is directly in contact with the rolled material, but it is low in other areas. Therefore, the cooling efficiency is low. Therefore, the applicant of the present application provided an immersion type cooling pipe with excellent cooling performance in Japanese Utility Model Publication No. 14965/1983. According to this method, cooling water is jetted out in opposite directions from annular nozzles provided at both ends of the cooling pipe to form a water film that covers the opening of the cooling pipe, and cooling water is directed into the pipe from the longitudinal center of the cooling pipe. The pipe was supplied with cooling water to fill the inside of the pipe. According to this immersion type cooling pipe, the high-temperature wire material running along the axis of the cooling pipe is immersed in the cooling water filling the pipe, which increases the contact time with the cooling water, and Uniform cooling results in extremely high cooling performance. This immersion type cooling pipe was developed with the main focus on how to fill the pipe with cooling water. However, subsequent research has revealed that the cooling capacity of immersion-type cooling pipes is greatly affected by the state of the flow of cooling water within the pipes. It has been found that the flow conditions are influenced by the tube structure and the selection of the nozzle pointing angle and nozzle slit width. Therefore, the present invention provides a novel cooling pipe structure based on the above research, and specifies the specifications of the nozzle to provide an immersion cooling pipe for wire rods and steel bars with improved cooling capacity. With the goal. Therefore, the feature is that cooling water is jetted inward from the annular nozzles provided at both ends of the cylinder having a horizontal axis and concentrically with the axis. In a cooling pipe that is filled with cooling water and immerses and cools a wire rod or steel bar that runs through the axial center of the cylinder, a drainage system that discharges the internal cooling water to the side surface of the axially midway part of the cylinder. When the mouth is opened, the inward pointing angle of the annular nozzle is set in a range of 30° or more and 60° or less with respect to the axis of the cylinder body,
Moreover, the slit width of the nozzle is set within a range of 3 mm or more and 7 mm or less. Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Immersion type cooling pipe 1 according to the present invention shown in FIG.
The cylinder body 2 is arranged horizontally and has both ends open, and the jacket 3 is fitted onto the outer peripheral surface of both ends of the cylinder body 2.
and a cooling water supply pipe 4 connected to the jacket 3.
The cylindrical body 2 includes an inlet guide part 5 and an outlet guide part 6 extending concentrically on both end surfaces of the cylinder body 2. The inner surface of the entrance guide portion 5 is formed into a tapered surface. A drain port 7 is provided on the lower surface of the axially central portion of the cylindrical body 2 . The portions located inside the jacket 3 at both ends of the cylindrical body 2, the entrance guide portion 5, and the exit guide portion 6 are connected to the jacket 3, respectively.
An annular nozzle 8 that communicates between the inside and the inside of the cylinder body 2 is configured. This nozzle 8 is concentric with the axis of the cylinder body and opens inward of the cylinder body 2, and the orientation angle with respect to the axis of the cylinder body 2 is θ ₁ on the inlet side and θ ₂ on the outlet side, as shown in FIG. Then, it is set so that 30°≦(θ ₁ , θ ₂ )≦60°. Further, if the slit width of the nozzle 8 is t, it is set to 3 mm<t<7 mm. According to the cooling pipe 1 according to the present invention, cooling water at a predetermined pressure is supplied into the jacket 3 through the supply pipe 4, and the cooling water is jetted inward from the annular nozzle 8 into the cylinder body 2. Ru. The jet stream from the nozzle 8 flows toward the center of the cylindrical body 2, collides at the center, and tends to fill the cylindrical body 2. At this time,
A portion of the cooling water is discharged from the drain port 7, while the remaining portion of the supplied cooling water is discharged from openings at both ends of the cylinder 2, filling these openings with water flow. As a result, the inside of the cylinder 2 is quickly filled with cooling water after the start of water supply, and reaches an immersed state. In the above-mentioned immersed state, the wire rod or steel bar 9 passes through the axial center of the cylinder 2 from the inlet guide portion 5, so that the wire rod 9 is immersed in the cooling water. cooled down. In the cooling pipe 1, the drain port 7 is provided on the side surface of the middle part of the cylindrical body 2, so that the effective replacement rate of cooling water in the cooling pipe 1 (the cooling pipe center drain port 7 for the cooling water supply amount Qs) is Cooling water discharge from
It was possible to increase the Qe ratio (Qe/Qs). In general, in immersion type cooling pipes, if the effective replacement rate of this cooling water is low, it means that some of the cooling water remains in the cooling pipes, and the average water temperature in the cooling pipes increases due to the pooling of cooling water. The cooling capacity for the stationary part of the rolled material becomes lower than the cooling capacity for the tip end of the rolled material. That is, a difference occurs in the temperature of the cooling water between the tip end portion and the stationary portion of the filament, resulting in non-uniform cooling in the longitudinal direction. On the other hand, if the cooling pipe has a conventional structure (as described in Utility Model Publication No. 14965/1983), in which cooling water is supplied from the center of the cooling pipe into the pipe and drained from both ends of the cooling pipe, If the length is short, there is no problem because the cooling water is replaced well, but if the length of the cooling pipe is long (in this example, the inner diameter of the cylinder 2 is about 60 mm to 120 mm, and the length is about 700 mm to 700 mm). 1000mm),
A portion of the cooling water would accumulate in the pipe, which would reduce the cooling water replacement rate, which was not preferable. In this embodiment, the effective replacement rate of the cooling water is increased by providing the drain port 7 on the side surface of the middle part of the cylinder 2, so that the problem of non-uniform cooling is solved. Next, the reason why the directivity angles θ ₁ and θ ₂ of the nozzle 8 and the slit width t are limited will be explained. The cooling capacity of the immersion type cooling pipe 1 is affected by the state of the flow of cooling water within the pipe. As a general tendency, the larger the cooling water supply amount Qs, the more the nozzle 8
As the slit width t becomes smaller, the speed of cooling water ejected from the nozzle 8 increases, and more air is sucked in from the inlet and outlet sides of the cooling pipe 1.
The number of bubbles generated within the cooling pipe 1 increases. Furthermore, if the slit width t is the same, bubbles tend to occur more easily when the directivity angles θ ₁ and θ ₂ of the nozzle 8 are smaller. Generation of such bubbles causes a heat insulating layer to exist between the filament material 9 and the cooling water, which is undesirable for removing a boiling film (steam film) from the cooling surface, resulting in a decrease in cooling performance. It turns out. Therefore, cooling water supply amount Qs, nozzle orientation angle θ ₁ , θ ₂
As a result of experiments conducted with various slit widths t, it was found that when the directivity angles θ ₁ and θ ₂ of the nozzle 8 were smaller than about 30°, the amount of bubbles generated increased considerably. It has also been found that when the slit width t is smaller than about 3 mm, the amount of bubbles generated increases. Therefore, it was determined that θ ₁ , θ ₂ ≧30°, and t≧3 mm. Next, determine the upper limits of these values. In this type of immersion type cooling pipe 1, it is necessary to cool the rolled material while the cooling pipe 1 is always filled with cooling water. That is, if the immersion state is insufficient, cooling of the rolled material in the circumferential direction or longitudinal direction becomes non-uniform. Also, the amount of cooling water supplied until reaching the immersion state.
It is desirable that Qmin be smaller because it allows for a wider control range of the cooling water flow rate. In other words, if the maximum supply amount of cooling water to be used is Qmax, then Qmax
-The larger the value of Qmin, the larger the control range of the cooling water flow rate. This wide control range is particularly important in controlled rolling. Therefore, the directivity angles θ ₁ and θ ₂ of the nozzle 8 and the slit width t were variously changed, and the amount Qmin of cooling water supplied until the immersion state was reached was measured. The results are shown in FIGS. 2 and 3. FIG. 2 shows the relationship between the nozzle directivity angle θ and Qmim when the slit width t is constant (t=5 mm).
The value of Qmin tends to become considerably large when the nozzle pointing angle θ exceeds 60°. FIG. 3 shows the relationship between the slit width t and Qmin when the nozzle directivity angle θ is constant (θ=45°).
The value of Qmin tends to become considerably large when the slit width t exceeds 7 mm. Therefore, it is set that θ ₁ and θ ₂ ≦60°, and t≦7 mm. To summarize the above, in this kind of immersion type cooling pipe 1, when the slit angles θ ₁ , θ ₂ and the slit width t are smaller than 30° and 3 mm, respectively, the amount of bubbles generated in the cooling pipe 1 is reduced. It becomes significantly larger and the cooling capacity decreases. Also, if these become larger than 60° and 7mm, respectively, the value of Qmin, that is, the cooling pipe 1
The amount of cooling water required to fill the interior with cooling water (become immersed) increases, which is undesirable because the control range of the cooling water flow rate becomes smaller. Table 1 shows that in this type of immersion cooling pipe 1, the nozzle orientation angle θ ₁ =θ ₂ =45° and the slit width t=5.
A comparison of the cooling capacity when mm and t=2.0 mm is shown.

[Table] As is clear from this table, the slit width t is 2mm.
The cooling capacity of the 5mm one is lower than that of the 5mm one. The embodiment shown in FIG. 4 is another embodiment of the present invention, and the difference from the embodiment shown in FIG. It is in the point where it is. By providing the exhaust hole 10 in this manner, bubbles generated within the cooling pipe 1 can be easily discharged, contributing to an improvement in cooling performance. It should be noted that the present invention is not limited to each of the above-mentioned embodiments, and the drain port 7 may be provided above the cylindrical body 2. According to the present invention, the effective replacement rate of cooling water in the cooling pipe is improved, and the cooling capacity is improved.
Since the nozzle orientation angle and slit width are set to appropriate values, it is possible to prevent the generation of bubbles in the cooling pipe, improve the cooling capacity, and widen the control range of the cooling water supply amount. Uniform and desired cooling of the strip material is achieved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a cooling pipe showing an embodiment of the present invention, and FIG. 2 is a slit width t=
A graph showing the relationship between the nozzle orientation angle θ and the cooling water flow rate Qmin required to reach the immersion state (the cooling pipe is filled with water) when the nozzle orientation angle θ is 5 mm. Figure 3 is for the nozzle orientation angle θ = 45°. FIG. 4 is a graph showing the relationship between the slit width t and Qmin required to reach the immersion state, and FIG. 4 is a sectional view of another embodiment according to the present invention. 1...Cooling pipe, 2...Cylinder, 7...Drain port, 8
...Annular nozzle, θ...Nozzle pointing angle, t...
Slit width.

Claims (1)

[Claims] 1. Cooling water is jetted inward of the cylinder from annular nozzles provided at both ends of a cylinder having a horizontal axis so as to be concentric with the axis to fill the inside of the cylinder with cooling water. In a cooling pipe for immersion cooling a wire rod or steel bar that runs through the axial center of the cylinder, a drain port for discharging the internal cooling water is provided on the side surface of the axially midway part of the cylinder, and The inward pointing angle of the nozzle is 30° or more and 60° relative to the axis of the cylinder.
An immersion cooling pipe for wire rods and steel bars, characterized in that the slit width of the nozzle is set in the following range, and the slit width of the nozzle is set in the range of 3 mm or more and 7 mm or less.