JPS63250421A - Method for cooling wire rod - Google Patents

Abstract

PURPOSE:To uniformly cool high temp. wire rods over the whole length at a wide range of cooling speed by supplying coolant containing many foams at large overlapping density sections of series group of the high temp. wire rod rings being carried with each center successively shifted. CONSTITUTION:The hot rolled high temp. wire rod is carried out on a conveyor 1 through a laying head (no figure) as ring state, to form the wire rod ring group S overlapping while shifting the center. The above conveyor 1 carried the wire rod ring group S while shifting at inside of a side guide 3 in a channel 2. To the wire rod ring group S under carrying, the foaming coolant composing of thin film of water solution containing surface active agent or water soluble polymer, forming by a water solution tank 8, air tank 9 and foaming device 10 is supplied through a supplying tube 7, header 5 and foam spraying nozzle 6, to cool the wire rod. Then, the above nozzles 6 are intensively arranged to the part of large overlapping density of the side end parts A in the wire rod ring S, to supply the foam more than to the small over-lapping density near at the center part B, so as to uniformly cool over the whole length.

Description

Detailed Description of the Invention (Industrial Application Field) This invention relates to a method for cooling high-temperature wire rods following a hot rolling process, and in particular to a method for conveying successive groups of overlapping hot wire rings with offset centers on a conveyor. The present invention relates to a method for cooling by supplying a refrigerant.

(Prior art) Air and mist methods are used to heat-treat high-temperature wire rods by rapidly cooling or slowly cooling them following hot rolling.

A method of spraying water, etc., a method of immersion in a metal bath such as liquid or lead, a method of immersion in a liquid such as hot water, cold water, or oil, or a hot liquid in a fluidized agitation state as shown in JP-A No. 57-9826. There are methods such as immersion.

Each of these methods is used depending on its purpose, and most of them have excellent features despite having a single function. but,
In order to cope with high-mix, small-lot production, which is a trend in steel manufacturing technology in recent years, it is necessary to install multiple cooling devices, which complicates the manufacturing process and increases equipment costs.

As a countermeasure against these problems, a multifunctional heat treatment system was developed as introduced in the Bulletin of the Japan Institute of Metals, Vol. 25, No. 6 (+986) P, 559. The feature of this system is that it uses an air cooling method for cooling rates below 10°C/S, and an immersion method for cooling rates higher than that.
It has a line structure, and the immersion line has a refrigerant circulation device etc. for cooling in a fluidized and agitated state. Furthermore, the air cooling line is equipped with a heat insulating cover and a blower, and is designed to obtain a desired cooling rate of 2 to 100°C/S.

However, in the case of controlled cooling of spring steel and high carbon steel wire rods, especially spring steel, if immersion cooling is performed in hot water near the boiling point, the cooling rate is too fast and a suitable cooling structure is generated. If this happens, the cooling rate will be non-uniform, leading to the problem of ferrite decarburization occurring in areas where the cooling rate is slow. For this reason, blast cooling is generally used as a means of achieving a cooling rate intermediate between immersion cooling in hot water and natural cooling in the atmosphere.

In the above-mentioned blast cooling method, when the non-concentric wire rings are coiled by the laying head and are continuously placed on the conveyor and cooled, the degree of overlap of each wire ring is as follows:
Since the amount of air flow varies from the center of the wire ring to both sides, countermeasures are required, such as changing the amount of air blast depending on the degree of overlapping of the wire rings.

When cooling a wire rod formed into a non-concentric wire ring shape while being conveyed on a conveyor, the overlapping density of the wire rods at both ends of the wire ring is large and the refrigerant is in sufficient contact with the wire rod shape compared to the single wire-shaped portion in the center of the wire ring. The disadvantage is that cooling becomes weaker.

Further, as a cooling method for homogeneous patenting, there is an immersion cooling method in a fluid refrigerant in a strongly agitated state of gas and hot water.

(Problems to be Solved by the Invention) However, in the blast cooling method, conventionally, air is applied from below to the overlapping portion of the wire rings, making uniform cooling difficult, and variations in the cooling rate within one wire ring result in heat loss. It is larger than that of materials treated by immersion cooling in water. Therefore, variations in mechanical properties such as tensile strength become large, causing problems such as having a negative effect on tool wear during secondary machining and causing bending during straightening. Ta.

In addition, in the method of immersion cooling in a strongly agitated fluid refrigerant of gas and hot water, since the refrigerant is in a strongly agitated state,
．． Small-diameter wire rods around 5 mmφ are placed on a conveyor and shake during the overloading process, causing trouble during conveyance and partial scale peeling, resulting in mechanical descaling before secondary processing. It can cause skin irritation during pickling. Furthermore, in order to blow a large amount of air, running costs such as blowers and refrigerant circulation devices are required.
This not only leads to larger and more complex equipment, but also has the problem of extremely high equipment costs.

SUMMARY OF THE INVENTION The present invention aims to improve the above-mentioned drawbacks and provides a method for cooling a hot-rolled wire rod, which can cool the hot-rolled wire rod uniformly over its entire length and at a cooling rate within a wide range.

(Means for Solving the Problems) The wire cooling method of the present invention involves forming a continuous group of overlapping high-temperature wire rings on a conveyor so that their centers are shifted, and while conveying the wire ring group by the conveyor. In the method of cooling by supplying a refrigerant, the refrigerant is foam, and more foam is supplied to a portion of the wire ring where the overlapping density is high than to a portion where the overlapping density is low. The foam is formed by a thin film of an aqueous solution containing at least one of a surfactant or a water-soluble polymer.

In order to form a wire rod ring group, the wire rod is sent out in a ring shape from a winding head of a winding machine onto a conveyor as is conventionally done.

Foam can be generated by an air supply method, a stirring method, a shaking method, a boiling method, a pressure reduction method, a solubility reduction method, or the like. In the air supply method, air, an inert gas such as N2, or a reducing gas is blown into an aqueous solution containing a foaming agent. For example, a spray nozzle is used to supply the foam to the wire ring. The foam injection nozzle may be disposed on either the upper or lower side of the wire ring, and may also serve as the cold water supply nozzle for quenching. In order to supply more foam to a portion of the wire ring with a high overlap density than to other portions, the foam is supplied from, for example, a foam injection nozzle that is concentrated on the portion of the wire ring with a high overlap density. Alternatively, foam having a higher moisture content may be supplied to a portion of the wire ring where the overlap density is higher than to other portions.

The amount of water in the foam is controlled by the ratio of the foaming agent to water in the aqueous solution containing the foaming agent, the type and concentration of the foaming agent, or the amount of air blown into the aqueous solution containing the foaming agent.

The lower limit water content in foam is 0.01g7100 (foam 10
0+++ (meaning that 0.01 g of water is included in λ) is desirable.

This is the limit water content that allows continuous cooling of a high-temperature wire rod by immersing it in foam. In other words, the water content in the foam is O
When the amount of water is less than 7100ml, the water content hardly plays a role as foam that affects the cooling rate. In addition, the temperature of an aqueous solution containing a blowing agent is lowered to below room temperature to generate foam, and the cooling rate obtained when cooling with the foam is just the amount of water that exceeds the cooling rate obtained by cooling with conventional air. be. Further, it is desirable that the upper limit water content in the foam is 80 g/]00 mQ. This water content was selected with a slight margin to the water content required to satisfy the cooling rate of 10 to 30° C./sec obtained by immersion in a strongly agitated refrigerant in a conventional multifunctional system.

As mentioned above, foams are made from aqueous solutions containing surfactants and water-soluble polymers.

The surfactant referred to here refers to a water-soluble batter compound that adsorbs to the surface of gas and liquid and reduces surface activity.
More specifically, fatty acid salts, higher alcohol sulfate ester salts, liquid fatty oil sulfate ester salts, sulfates of aliphatic amines and aliphatic amides, fatty alcohol phosphate ester salts, sulfone salts of dibasic fatty acid esters, fatty acids Anionic activators such as amidosulfonates, alkylarylsulfonates, formalin condensed naphthalene sulfonates, cationic activators such as aliphatic amine salts, quaternary ammonium salts, alkylpyridinium salts, and polyoxyethylene. Nonionic surfactants such as alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, and amphoteric surfactants such as alkyl betaines, alkyldimethylamine oxides, and alkylalanines. Main examples include activators, but they are not limited to stiffness.

When generating foam, one or two of these surfactants are used.
It is preferable to use a mixture of more than one species by adding it to water to a concentration of 0.001 to 404.

Water-soluble polymers include natural 2-synthetic and semi-synthetic water-soluble polymers, specifically cornstarch, starches, funori, agar, sodium alginate, gum arabic, gum tragacanth, troloalloy, konnyaku, glue, casein, and gelatin. , egg white, blood serum protein,
Pullulan, dextrin, carboxy starch, pritesh gum, dialdehyde starch, cationic starch.

Viscose, methylcellulose, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyvinyl alcohol, polyethylene glycol,
Polyalkylene glycol.

Main examples include polyacrylamide, polyacrylic acid, polyvinylpyrrolidone, water-soluble alkyd polyvinyl ether, polymaleic acid copolymer, polyethyleneimine 1-saponin, etc., but are not limited thereto.

For foam generation, one or more of these water-soluble polymers should be added to water at 0.00%. It is preferable to add and use O1 to 30t.

The above-mentioned surfactant and water-soluble polymer may be mixed and used in any proportion. In addition, in order to improve the properties and stability of foam, an appropriate amount of chelating agents, builders,
A higher alcohol or the like may be added.

Examples of chelating agents include dihydroxyethylglycine and hydroxyethyliminodiacetic acid.

nitrilotriacetic acid, and droxyethylethylenediamine 3
Aminocarboxylic acid salts such as acetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, sodium citrate,
Oxycarboxylic acids and polycarboxylic acids such as sodium gluconate and sodium tartrate.

There are phosphonic acids such as hydroxyethane diphosphonic acid, nitrilotrismethylenephosphonic acid, and ethylenediaminetetramethylenephonic acid, and condensed phosphates such as sodium tripolyphosphate and sodium birophosphate.
It is preferable to use 0.001 to 2096 seeds or more.

In addition, higher alcohols are primary and secondary alcohols having 6 to 36 carbon atoms.
preferred are alcohols of the same grade, and one or more of hexanol, octatool, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, Guerbet alcohol having a carbon number of 18° to 24.36, etc., is used as a surfactant. 0.5 to 3
0% may be added.

Other builders such as sodium silicate, sodium sulfate,
Sodium carbonate, etc., was added to the above formulation at a rate of 0. 1 to 30 may be added.

Usually, the temperature of the aqueous solution containing the foaming agent is between 0° C. and 100° C., but it is desirable to use it at room temperature and control the amount of water in the foam to obtain the desired cooling rate from the viewpoint of energy saving. It is also possible to preheat the temperature of the blown gas before use.

(Function) The foam supplied to the wire rod ring group enters between the rings and adheres to the wire surface. The aqueous foam film adhering to the wire surface evaporates due to the heat retained in the wire and is cooled by a combination of boiling heat transfer and radiation heat transfer.

The surfactant in the foam adsorbs to the surface of the gas and liquid, lowering the surface tension, and increasing the surface viscosity to improve the foamability during foam formation, the size or uniformity of the foam diameter, stability, etc. Furthermore, the water-soluble polymer in the foam improves the surface viscosity or surface viscoelasticity of the gas-liquid surface, forming a stable foam.

Since more foam is supplied to the portion of the wire ring where the overlap density is high than to the portion where the overlap density is low, the foam sufficiently surrounds the ring. Therefore, even if the evaporation rate of the aqueous solution in the foam increases and the amount of heat removed increases in areas where the wire rings overlap at a high density, the foam is sufficiently replenished and will not disappear. As a result, the portions with high overlap density are cooled in the same way as the portions with low overlap density, and the wire is cooled uniformly over the entire length.

The cooling capacity of the foam changes depending on the amount of water in the foam, and the water content 1 can be adjusted over a wide range. Therefore, in a single cooling facility, the cooling rate of the wire rod can range over a wide range (ranging from cooling with cooling water to natural cooling in the atmosphere, for example, wire diameter) from 1 to b in the case of 0+nm.

(Example) Figures 1 and 2 show examples of the present invention, respectively. Figure 1 is a plan view showing a group of wire rings being conveyed on a conveyor, and Figure 2 is a cooling equipment. FIG.

The hot-rolled wire rod is sent out in a ring shape from a winding head (not shown) onto a conveyor 1.
A wire ring group S is formed on the conveyor 1. In the wire ring group S, the wire rings overlap closer to each other in the side A than in other parts B.

The conveyor 1 is housed in a channel 2, and side guides 3 are provided on both sides.

A header 5 is arranged directly below the conveyor 1, and foam injection nozzles 6 are attached to both ends of the header 5, respectively. The foam injection nozzles 6 are oriented toward both ends A of the wire ring group S. Further, an aqueous solution tank 8 storing an aqueous solution containing a foaming agent and an air tank 9 are connected to the header 5 to a foamer 10 via a supply pipe 7.

In the cooling equipment configured as described above, when the aqueous solution is blown into the foamer lθ together with air, the aqueous solution foams.
Foam F is ejected from the foam injection nozzle 6 toward both ends A of the wire ring group S. The ejected foam F spreads not only to both ends A of the wire ring group S but also to the entire channel 2, and the inside of the channel is filled with foam F. Wire ring group S
is immersed in this foam F and is cooled.

To give a specific example of wire cooling, the aqueous solution is room temperature water IJ2.
2.5 wt* of an anionic surfactant was added to the solution. This water dissolution is about 10i/min and air is about 20017
m1n was introduced into a foamer to generate foam. A wire rod with a diameter of 9.5 mmφ containing 0.4 t of C was heated to 900° C. and cooled by immersion in such foam. As a result, the wire rod is cooled uniformly, reducing quality fluctuations and lot fluctuations.
We were able to stably produce wire rods of the targeted quality.

FIGS. 3 and 4 each show other examples of cooling equipment implementing the present invention. In the following embodiments, members similar to those shown in FIG. 2 are given the same reference numerals, and detailed explanations thereof will be omitted. In addition, the aqueous solution tank, air tank, and foamer shown in Figure 2 are omitted.
Not shown.

In FIG. 3, the header 5 is arranged directly above the channel 2, and the foam injection nozzle 6 is located at the side end A of the wire ring group S.
It is slanted so that it is oriented. The foam F is supplied only into the side guide 3. In FIG. 4, the header 5 is placed directly above the channel 2, similar to the cooling equipment shown in FIG. The foam injection nozzle 6 is oriented between the side end A of the wire ring group S and the side guide 3.

This invention is not limited to the above embodiments. For example, when generating foam, an inert gas such as N2 gas or a reducing gas may be used instead of air from the viewpoint of preventing surface oxidation of the cooling wire.

(Effects of the Invention) In this invention, foam made from an aqueous solution containing a surfactant and a water-soluble polymer is used as a refrigerant, so the foam produced is uniform and stabilized, and the foam has a uniform water content. Layers can be created arbitrarily. This makes it easier to control the cooling atmosphere, and it is possible to stably produce wire rods of the target quality with less quality fluctuations and lot fluctuations.

Compared to the conventional method of cooling the wire by applying wind, the present invention can uniformly cool the wire over its entire length.

In addition, compared to the conventional method of cooling by immersing in a hot liquid under strong stirring, the material resistance is lower, and even with small diameter wires such as 5.5 mmφ, the material properties are good, and there is no peeling of scale. There are no problems such as rough skin caused by acid washing. In addition, it does not require refrigerant treatment, evaporation equipment, refrigerant circulation equipment, etc., has a simple structure, and has very low equipment costs.

Further, in the present invention, the cooling rate can be controlled over a wide range by controlling the water content and temperature of the foam. Therefore, compared to conventional methods, mechanical properties such as tensile strength of the wire can be adjusted over a wide range with one cooling facility.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a group of wire rod rings being conveyed on a conveyor, FIG. 2 is a longitudinal sectional view showing an example of cooling equipment for carrying out this invention, and FIGS. 3 and 4 are FIG. 7 is a vertical cross-sectional view showing other examples of cooling equipment. ! ...Conveyor, 2...Channel, 3...Side guide, 5...Header, 6...Foam injection nozzle,
7... Supply pipe, 8... Aqueous solution tank, 9... Air tank, 10... Foaming device, A... Side end of wire ring group, B... Central part of wire ring group , F...foam, S... wire ring group.

Claims (3)

[Claims] (1) A method in which a continuous group of high-temperature wire rings overlapping with their centers shifted is formed on a conveyor, and a refrigerant is supplied and cooled while the wire ring group is conveyed by the conveyor, wherein the refrigerant is a surfactant. and a foam formed by a thin film of an aqueous solution containing at least one of a water-soluble polymer, and is characterized by supplying more foam to areas of the wire ring that overlap and have a higher density than areas that overlap and have a lower density. Method. (2) The method for cooling a wire rod according to claim 1, characterized in that foam is supplied from a foam injection nozzle that is concentrated in a portion of the wire rod ring where the overlapping density is high. (3) The method for cooling a wire rod according to claim 1, characterized in that the moisture content of the foam supplied to the portion of the wire rod ring with a high overlap density is larger than that supplied to the portion of the wire rod ring with a low overlap density.