JPH0611881B2 - Cooling method and cooling device for heat extraction drum - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used, for example, in the case of producing metal fibers, flaky metal chips, foil metal chips, and the like, which are used as other composite materials for concrete reinforcement. The present invention relates to a cooling method and a cooling device for a heat extraction drum.

[Conventional technology]

Regarding the conventional production of this type of metal fiber, for example, there is one disclosed in Japanese Patent Publication No. 53-4496. This is, as shown in FIG. 5, a rotating cylindrical drum 2
A plurality of threads or thread-projecting blades 3 are formed on the outer peripheral surface of, and the outer peripheral edge of the projecting blades 3 is brought into contact with the surface of the molten metal 4 and is sequentially attached, and After removing heat from the adhered matter to solidify it, it is peeled off from the protruding blade 3 to obtain a metal fiber.

Further, Japanese Patent Application Laid-Open No. 60-204647 discloses a technology for manufacturing a flaky metal chip, and Japanese Patent Application Laid-Open No. 61-69903 discloses a technology for manufacturing a foil metal chip.
All of them are equipped with a projecting blade consisting of a number of independent projections on the outer peripheral surface of a rotating cylindrical heat extraction drum, and the heat is taken from the molten metal deposited in the same way as above to solidify it. After that, it is peeled off from the protruding blade to obtain a metal chip.

By the way, the heat extraction drum used in the production of such metal fibers or the like takes a large amount of heat from the adhering molten metal to solidify it, so that a large cooling capacity is required. Therefore, conventionally, a metal having a high thermal conductivity such as copper is used as a drum material, and as shown in FIG. 6, the heat extraction drum 10 is forcibly cooled from the inside with a cooling substance 1 such as water. Was being done.

[Problems to be Solved by the Invention]

However, the above conventional cooling technique has the following problems.

The flow of the cooling substance diffuses in the heat extraction drum,
Since the entire heat extraction drum is not cooled uniformly, not all of the molten metal that comes into contact with the protruding blades on the drum peripheral surface solidifies, resulting in poor production efficiency.

When the molten metal contacts and solidifies on the protruding blade, solidification growth stops in the middle of the protruding blade, and for example, a metal fiber having a target length cannot be obtained, resulting in a defective product.

In addition, the cooling efficiency of the heat extraction drum is low and the degree of cooling is weak, so the solidification speed when the molten metal contacts and solidifies the protruding blade is slow, the detachment from the protruding blade is delayed, and the forced removal by the wiper increases. Shorten the wiper life.

The increased adhesion of metal fibers to the wiper promotes wear on the surface of the heat extraction drum, shortening the life of the drum.

Therefore, the present invention has been made by paying attention to the above conventional problems, and an object thereof is to provide a cooling method and a device capable of cooling the heat extraction drum uniformly and efficiently, It is to solve the above-mentioned conventional problems.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the method of the present invention is a cooling method for a heat extraction drum, in which a protruding blade on the peripheral surface is brought into slight contact with the surface of the molten metal so as to rotate, and along the vicinity of the inner wall of the drum. The cooling substance is forced to flow only in

Further, the device of the present invention is a cooling device for a heat extraction drum, which is provided with a protruding blade on the peripheral surface and is formed so that the protruding blade slightly contacts the surface of the molten metal and rotates. Inside the extraction drum, a bush having an outer wall surface opposed to the inner wall surface of the drum with a slight clearance is disposed, and a clearance between the outer wall surface of the bush and the inner wall surface of the drum is defined as a flow path of a cooling substance. did.

[Action]

A narrow gap was provided between the inner wall surface of the heat extraction drum and the outer wall surface of the bush facing it, and the flow path of the cooling substance was regulated near the inner wall of the drum, so that the flow of the cooling substance was uniform. became. As a result, all the molten metal in contact with the protruding blade can be solidified and the production efficiency is improved.
In addition, the solidification of the molten metal attached to the protruding blade did not stop halfway, and no defective metal fiber was produced.

And, again, the flow of the cooling material became faster. as a result,
The cooling degree of the heat extraction drum was strengthened, the solidification rate of the molten metal on the protruding blade surface was increased, the forced removal by the wiper was reduced, and the life of the wiper was extended. Further, the wear of the surface of the heat extraction drum due to the metal fibers attached to the wiper was suppressed, and the life of the heat extraction drum was extended.

By the way, regarding the relationship between the flow velocity of the cooling substance and the cooling strength, the amount of heat transferred from the heat extraction drum to the cooling substance Q
Is generally expressed by the following equation (1).

Q = h (T ₁ −T ₂ ), (T ₁ > T ₂ ) ... (1) where h: heat transfer coefficient between the drum and the cooling material T ₁ : temperature of the drum T ₂ : cooling material The heat transfer coefficient h is generally expressed by the following equation (1).

^{h = A · Re n · Pr} m, (n> 0, m> 0) ... (2) Here, A: constant, n, m: constant Re: Reynolds number Pr: Prandtl number Reynolds number Re is, cooling Since it is proportional to the flow velocity of the substance, when the flow velocity of the cooling substance is increased, the heat transfer coefficient h increases, and the amount Q of heat transferred from the heat extraction drum to the cooling substance increases. Therefore, increasing the flow rate of the cooling material will enhance cooling of the heat extraction drum.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention. The same or equivalent parts as in the prior art are designated by the same reference numerals. The cylindrical body 11 of the heat extraction drum 10 is made of copper and has a plurality of protruding blades 3 formed on the outer peripheral surface thereof. Both end portions in the axial direction are covered by the side plate 12. A rotary shaft 13 penetrating the side plate 12 is attached to the shaft center portion. A bush 14 is integrally formed on one side plate 12, and is inserted into the heat extraction drum 10 through a rotary shaft 13. The inner wall surface 10a of the heat extraction drum 10 and the outer wall surface 14a of the bush 14 facing the inner wall surface 10a are separated from each other by a clearance of a slight clearance dimension H. This clearance is the flow path 16 in the drum of the cooling water 1 as the cooling substance. Rotating shaft 13
Is a double pipe, and the inner pipe 17 at the center portion forms a feed passage for the cooling water 1. A cooling substance inflow port 18 communicating with the flow passage 16 is bored in the inner pipe 17. On the other hand, the outer tube 1
A cooling substance discharge port 20 is provided in 9 so as to communicate with the flow path 16. Reference numeral 21 is a backflow stopper inserted between the inner pipe 17 and the outer pipe 19.

The cooling water 1 flows into the flow path 16 in the drum from the cooling substance inflow port 18 via the inner pipe 17. And heat extraction drum 1
Along the inner wall surface 10a of 0, the heat is exchanged with the cylindrical body portion 11 while flowing in the flow path 16 at high speed in the axial direction from one end side to the other end side of the drum. After that, the discharge port 20
Emitted from.

FIG. 2 shows a modified example. In this case, the cooling water 1 has a cooling substance inlet 18 at the center of the bush 14.
Flow into the channel 16. Then, the heat is exchanged with the cylindrical body 11 while flowing from the center of the cylindrical body 11 toward both ends and flowing at high speed. After that, it flows through the outer pipe 19 from the discharge ports 20 at both ends of the drum and is discharged.

Next, examples of the present invention will be described.

In this experiment, using the apparatus shown in FIG. 1, the relationship between the relative flow velocity of the cooling water with respect to the heat extraction drum 10 and the clearance dimension H of the flow path 16, and the relative flow velocity of the cooling water and the rotation speed of the heat extraction drum 10 were also used. It was a study of the relationship with.

Here, the relative flow velocity of the cooling water means the heat extraction drum 1
It is defined as the vector sum of the average flow velocity flowing in the drum when there is no rotation of 0 and the flow velocity in the circumferential direction of the heat extracting drum 10 when the cooling water flowing in the drum is delayed due to the rotation of the heat extracting drum 10.

The dependency of the relative flow velocity of the cooling water on the drum rotation speed is determined by the flow path 16
FIG. 3 shows the results of the test obtained by using the clearance dimension H as a parameter.

Further, FIG. 4 shows the result of the test for determining the dependence of the relative flow velocity of the cooling water on the flow passage clearance dimension H.

From the results of the above experiment, the following was clarified.

Due to the increase in the number of rotations of the heat extraction drum 10, the relative flow velocity of the cooling water is improved.

There is a clearance dimension H of the flow path 16 that maximizes the relative flow velocity of the cooling water, and the value is about H = 5 mm in the above experiment.

The clearance dimension H of the flow path 16 is to some extent (1 in the above experiment)
If it becomes larger than 0 mm), the backflow of the cooling water will occur in the flow path 16.

Therefore, on the basis of the above experimental results, a comparative test of metal fiber production was conducted between the one in which the clearance dimension H of the flow path 16 was set to H = 5 mm and the one in the conventional apparatus shown in FIG.

However, the flow rate of the cooling water was measured at 10a part. The results are represented by the productivity ratio with the conventional device as 100%.

The results of the comparative test are shown in Table 1.

From the comparison between Test # 1 and the conventional method, the productivity of the metal fiber was improved by 30% by increasing the cooling water flow velocity and stabilizing the flow.

From the comparison with Test # 2, by further lowering the cooling water temperature to 10 ° C., the productivity of the metal fiber was improved by 35%.

From the comparison with Test # 3, by further lowering the cooling water temperature to 2 ° C., the productivity of the metal fiber was improved by 45%.

That is, by limiting the flow of cooling water in the heat extraction drum 10 along the vicinity of the inner wall of the drum by inserting the bush into the drum, the outer peripheral surface of the heat extraction drum 10 is uniformly cooled and the cooling efficiency is improved. As a result, the time at which the adhered molten metal is released from the solidified protruding blade 3 becomes earlier. As a result, the peripheral speed of the heat extraction drum 10 can be increased, and the productivity of metal fibers is improved.

Further, since the metal fibers are easily detached from the surface of the heat extraction drum 10, the adhesion to the wiper for wiping the drum is reduced and the life of the wiper is extended.

Furthermore, the number of defective products such as deformed fibers was reduced.

In addition, in the above-mentioned embodiment, the case of the metal fiber has been described, but it is not limited to this, and it is needless to say that the present invention can be applied to the case of a piece-shaped metal chip or a foil-shaped metal chip.

〔The invention's effect〕

As described above, according to the present invention, a bush having an outer wall surface opposed to the inner wall surface of the drum with a slight clearance is arranged inside the heat extraction drum, and the outer wall surface of the bush and the inner wall surface of the drum are arranged. The cooling substance is allowed to flow only in the vicinity of the inner wall of the drum by setting the clearance between the cooling substance and the channel as the flow passage of the cooling substance. Therefore, the entire heat extraction drum can be cooled uniformly and the cooling efficiency can be improved. As a result, all the molten metal that comes into contact with the protruding blade on the peripheral surface of the drum is solidified, and the production efficiency is improved.
The solidified growth of the molten metal on the protruding blade becomes good, and the number of defective products decreases. When the molten metal is solidified by contact, the solidification speed is fast, the molten metal is easily separated from the protruding blade, and the life of the wiper is extended. The wear of the surface of the heat extraction drum due to the metal fibers attached to the wiper is suppressed, and the life of the drum is extended.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part of an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of an essential part of a modification thereof, and FIG. 3 is a graph showing the drum rotation speed dependency of the cooling water flow velocity in the present invention. FIG. 4 is a graph showing the flow passage clearance size dependency of the cooling water flow velocity in the present invention, FIG. 5 is a partial cross-sectional perspective view showing a state in which the conventional heat extraction drum is in contact with the surface of the molten material, and FIG. FIG. 8 is a vertical sectional view of a main part of a conventional heat extraction drum. Reference numeral 1 is a cooling substance, 2 and 10 are heat extraction drums, 10a is an inner wall surface thereof, 14 is a bush, 14a is an outer wall surface thereof, and 16 is a flow path.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuyuki Kurisu 475-1 Miike-machi, Kanazawa-shi, Ishikawa Inside the Kanazawa Plant of Nippon Metallurgical Industry Co., Ltd. (56) References Japanese Patent Publication No. 53-4496 (JP, B2)

Claims (2)

[Claims] 1. A cooling method for a heat extraction drum, wherein a protruding blade on the peripheral surface is brought into slight contact with the surface of the molten metal so as to rotate, and the cooling substance is restricted only near the inner wall of the drum. A method for cooling a heat extraction drum characterized by forced flow. 2. A cooling device for a heat extraction drum, comprising a protruding blade on its peripheral surface, the cooling blade being formed so as to rotate while slightly contacting the protruding blade with the surface of the molten metal. Inside, a bush having an outer wall surface opposed to the inner wall surface of the drum with a slight clearance is disposed, and the clearance between the outer wall surface of the bush and the inner wall surface of the drum is used as a flow path for the cooling substance. Characteristic cooling device for heat extraction drum.