JPH02182838A - Method and equipment for direct heat treating steel wire rod - Google Patents

Abstract

PURPOSE:To obtain the steel wire rod having high tensile strength and excellent drawability by forcedly passing air over the surface of a cooling medium bath consisting of an air-water mixed-phase fluid in a heat-treating bath and dipping a hot-rolled steel wire in the both. CONSTITUTION:The hot-rolled steel wire rod 1 is wound and dropped by a laying head 3, and moved 5 into the cooling medium constituting of hot-water. Film boiling is produced on the surface of the wire 1 in the formed air-water mixed-phase cooling medium 8 to cool the wire. Meantime, air or steam is blown into the medium 8 to keep the medium 8 at <=95 deg.C, the wire is patented by the conventional method for a medium- or high-carbon steel wire, and further air is forcedly blown against the surface of the medium 8 to rapidly deprive heat from the surface. The medium 8 is kept at a set temp. by both means. the wire rod 1 is stably hat-treated in this way. In addition, 4 in the figure is a ring shape wire, 6 is a treating bath, and 20 is forced-air blower.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to, for example, springs, PC (prestressed concrete M) steel wires, PCI! 4. Used for stranded wire, etc.
When manufacturing high carbon steel wire rods, hot rolled steel wire rods are forcibly cooled with a refrigerant to obtain wire rods with high tensile strength and excellent wire drawability. Concerning direct heat treatment method and equipment.

[Prior art] A direct heat treatment method and apparatus capable of producing medium- to high-carbon steel wire rods that are equivalent to lead patenting, have little variation in quality, and have good wire drawability are disclosed in Japanese Patent Application Laid-Open No. 248112.
It is disclosed in Publication No. 4.

In this method, a ring-shaped coil of high-carbon steel wire is transferred in an almost horizontal direction in an expanded form at a high temperature where the hot-rolled metal structure exhibits austenite, and is in a strongly disturbed state. A large number of oxidizing bubbles are uniformly dispersed 9
When the refrigerant is immersed and passed through a tank containing a refrigerant made of a gas-water multiphase fluid maintained at a predetermined temperature of 5° C. or less, and subjected to controlled cooling and direct heat treatment to transform into a fine pearlite structure, the refrigerant is directly heat-treated. In this method, the wire is directly heat-treated by causing the wire to flow in a predetermined direction to provide uniform cooling conditions over the entire length of the wire.

The equipment shown in FIG. 4 is disclosed as a means for realizing such a direct heat treatment method.

Here, the above equipment will be explained.

The hot rolled steel wire 1 is passed through pinch rollers 2.
It is drawn into the laying head P3, transformed into a ring-shaped wire rod by the laying head 3, rolled off as a non-concentric ring wire rod 4 onto a horizontally installed conveyor 5, pre-cooled during the movement, and sequentially heat-treated from the end of the conveyor 5. The materials are transferred onto a horizontal conveyor 7 disposed in the tank 6, further transferred onto an inclined conveyor 17, and bundled by a bundler (not shown) outside the heat treatment tank.

During this time, the wire rod 4 undergoes controlled cooling in the heat treatment tank 8. For the controlled cooling, a discharge pipe 11 is connected to the wire discharge side of the heat treatment tank 6. (2) is connected to the heat exchanger 15, shunts, joins again, and is connected to the hot water tank 14. The hot water tank 14 is kept at a constant temperature by regulation for controlled cooling, and the hot water supply pipe 12 is connected to the heat treatment tank 6 above the drawing part of the wire 4 of the heat treatment tank 6 by means of a circulation pump IG. Ru.

Further, a plurality of upward nozzles are provided mainly on the lower side in the length direction of the horizontal conveyor 7 to blow out air from the gas supply pipe 10 provided at the bottom of the heat treatment tank 6, for example.
The air is cut approximately 11 times by a bubble cutter 9 disposed close to it.
■ The refrigerant is transformed into the above-mentioned fine bubbles, is further agitated by the stirrer 19, and rises to the top from between the horizontal conveyors 7, flowing as a whole in the moving direction of the horizontal conveyor 7 as a refrigerant made of hot water, and maintaining such a constant temperature. It is configured so that so-called batenting processing can be performed using hot water held in the hot water and a refrigerant made of air-water multiphase fluid of air bubbles mixed with the hot water.

[Problems to be Solved by the Invention] By the way, as understood from the above description, this equipment is used as a means for controlling the temperature of hot water, and is capable of controlling the flow rate of the blown gas (air, steam, etc.) in the air-water multiphase fluid, and The temperature is controlled by mixing cold water and hot water, and the refrigerant is circulated using the mixed air/water multiphase fluid. However, the temperature control of the refrigerant using the air/water multiphase fluid is directly dependent on the characteristics of the heat-treated wire. However, as a refrigerant temperature control method for this purpose, equipment that uses a mixed circulation system of cold water and hot water is relatively expensive and has high operating costs. Although it is possible to control the temperature to some extent by adjusting the flow rate of the blown gas, it becomes impossible to control the temperature when the amount of wire rod rolling becomes excessive. In addition, there is a limit to the flow rate of the blown gas due to the functionality of the refrigerant, and if the flow rate is excessive, the behavior of the wire cooling becomes unstable as a result of gas blow-through, formation of cold water masses, etc. There is a problem that direct heat treatment of the wire rod cannot be performed, and the amount of blown gas cannot be increased indefinitely.

[Means for Solving the Problems] The present invention has been made for the purpose of solving the above problems, and includes, as a refrigerant temperature control means: (1) a means for forcedly blowing air at the refrigerant bath surface of a heat treatment tank by adjusting the wind speed; Our company provides a method and equipment for direct heat treatment of steel wire, which is equipped with a means for adjusting the gas flow rate blown into the refrigerant made of air-water multiphase fluid, and can thereby control the refrigerant temperature, and is low in equipment cost and running cost. This is what it aims to do.

In this case, the forced air blowing to the refrigerant bath surface is adjusted, for example, in accordance with the rolling pitch (operation) of wire rod rolling, and while continuously measuring temperature fluctuations.

The present invention will be explained below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and the same parts as in FIG. 4 are designated by the same reference numerals. A laying head 3 is installed at a position slightly different from the heat treatment tank 6, and a conveyor 5 is placed horizontally and slightly downwardly inclined from just below the laying head 3 to inside the end of the heat treatment tank 6. A horizontal conveyor 7 . Although not shown, a piping IO is arranged so that the flow rate of the gas blown therein can be adjusted. A plurality of breakers 9 are arranged to operate against the gas (dry air, oxidizing gas) blown into the refrigerant 8 from the bottom, and a plurality of agitators 19 are arranged from the bottom to blow the gas (dry air, oxidizing gas) into the refrigerant 8. to give a stirring effect to the

Reference numeral 20 denotes a forced air blower, which has a structure in which the wind speed can be changed. 2I is a guide cover provided on the refrigerant bath surface of the heat treatment tank 6 in order to effectively blow dry air onto the bath surface.

FIG. 2 shows another embodiment of the present invention, in which dry air is effectively blown onto the bath surface of the heat treatment tank θ. A blower 20 that can change the wind speed is equipped with a dry air blowing hood 22 having a large number of air outlets 23.

[Function] The rolled wire rod 1 is rolled down by the rolling rod 3,
The refrigerant moves from the conveyor 4 to the inclined conveyor 5 and moves through the air-water mixed phase refrigerant.

At this time, when the wire 1 is cooled in hot water (refrigerant), heat exchange occurs between the hot water and the wire. The wire temperature decreases, the water temperature increases, and water vapor is generated.

In the present invention, the cooling process is performed by maintaining the refrigerant at a constant temperature of, for example, 80-95°C, and causing film boiling (referred to as subcool boiling) on the wire surface in the refrigerant using a steam-water multiphase fluid maintained at this constant temperature. This is what we do.

When processing at the boiling temperature of the refrigerant, the refrigerant temperature does not rise any further and can be maintained at a constant temperature, but in the case of subcooled boiling, the refrigerant temperature fluctuates during processing, so this is caused by bubbles in the refrigerant. In addition, by adjusting the flow rate of the gas blown into the heat treatment tank, the cooling rate of the refrigerant accompanying water evaporation is changed, and at the same time, by changing the speed of forced air over the bath surface of the heat treatment tank, the atmospheric gas such as almost saturated humid air is forced. exhaust,
The refrigerant temperature is controlled by supplying dry air or the like and evaporating it into dry air, thereby maintaining the refrigerant temperature at a set temperature of 80 to 95°C.

Tokuko Sho B! describes the process of patenting medium to high carbon steel wire rods by blowing a mixture of air or water vapor into hot water, such as air, to maintain the refrigerant temperature at a predetermined temperature of 95°C or less. As disclosed in JP-A-21289 and JP-A-59-219417, if the above-mentioned means alone is used, as mentioned above, if the flow rate of the blown gas is excessive, gas blow-through will occur, so in order to compensate for this, By adjusting the speed of forced air blowing to the surface of the refrigerant and rapidly discharging heat from the surface of the refrigerant, the refrigerant of the air-water multiphase fluid is maintained at a predetermined set temperature using both of the above means.

As mentioned above, by blowing in gas such as air, the bubbles formed produce strong agitation, which lowers the temperature and equalizes the temperature both macroscopically and microscopically. By spraying water vapor, the evaporation of water vapor from the bath surface can be promoted over a wide area.

Further, although not shown, the hot water that has been evaporated and cooled can be recirculated into the bath, and the hot water can be newly supplied to the bath surface and circulated.

Test Example 1 High carbon steel (composition 0.81%G, 0.24%Sl, 0.
51% Mn, balance Fe) was rolled into a wire rod with a diameter of 10.0 mm at a finish rolling temperature of 930° C. and a final wire rolling speed of 25 m/sea, wound into a ring shape, and then immersed in a refrigerant using an air-water multiphase fluid. and patented. The wire rod weight was about 1000 kg/bundle, and the operation was carried out continuously at a pitch of 5 seconds between each bap.

The forced air blowing equipment shown in Figure 1 was used as the equipment. The amount of air blown was 8 + a/sec.

Total weight of refrigerant is 20t1 Blowing gas flow rate is 1ift//1
It is n. In addition, the blown gas was cut into small-diameter bubbles by a mechanical cutter 9, and stable subcooled film boiling was performed for cooling.

The refrigerant temperature was measured and recorded on a chart to examine temperature changes.

FIG. 3 shows a chart of the results of this test. In the diagram■
~■ indicates the timing when the wire rod is immersed in the refrigerant in the processing tank, and the temperature measurement results of the processing refrigerant are shown in synchronization with this.

3 shows the refrigerant temperature change when the forced air equipment according to the present invention is operated.

On the other hand, ■ shown as a comparative example shows the refrigerant temperature change only due to air bubbles being blown into the refrigerant.

From the viewpoint of stable characteristics of the resulting wire, it is desirable that the refrigerant temperature, for example, the water temperature, be maintained at a set temperature at all times.

However, the large amount of energy contained in hot-rolled wire rods causes an increase in water temperature. In the case of the comparative example, the water temperature is
rise from the ground. In addition, the temperature rise range is large due to the insufficient capacity of just blowing air bubbles (in reality, 9G-9
This indicates that the wire is processed at 4°C.

On the other hand, in the case of ■, the increase in water temperature within a batch is small, and the increase in water temperature is constant even if the treatment is continuous, and it is 90 to 91%.
”It shows that it can be processed within the C range.

Test Example 2 The equipment shown in FIG. 2 is a ventilation equipment designed to provide a large number of air outlets to more effectively improve the cooling effect.

With the equipment having this configuration, dry air can be made to reach the target refrigerant interface from each air supply port.

Using this equipment, continuous patenting treatment was performed on a wire rod rolled under the same conditions as in Test Example 1, with the set temperature set at 87°C. It was possible to operate in the range of ℃.

[Effects of the Invention] According to the method of the present invention, the refrigerant temperature is maintained at a predetermined temperature of 80 to 95°C by adjusting the wind speed to forcefully blow air onto the refrigerant surface and by adjusting the gas that forms bubbles in the refrigerant. This allows for stable heat treatment of steel wire.

According to the equipment of the present invention, direct heat treatment of wire rods by subcooled boiling using a steam/water multiphase fluid can be performed without using the equipment that requires large capital investment and running cost, which is conventionally proposed. Equivalent temperature control is possible with simpler equipment.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention. FIG. 3 is a chart of hot water temperature changes during operation of the equipment of the present invention and the conventional equipment. Figure 4 shows conventional equipment equipped with a hot water tank for adjusting hot water temperature. 1...Hot rolled steel wire rod, 2...Pinch roller-3.
... Laying head, 4... Ring-shaped wire rod, 5...
Conveyor, 6... Processing tank, 7... Horizontal conveyor, 8
... air-water multiphase refrigerant, 9... name cutter, IO... pipe, 11... refrigerant discharge pipe, 12... refrigerant supply pipe, IB-... stirrer, 20... Blower, 21... Guide cover, 22... Hood for dry air blowing. Processing crowd (6C)

Claims (2)

[Claims] (1) Direct heat treatment of the steel wire rod, which is cooled by immersing the hot-rolled steel wire rod in a non-concentric manner in a heat treatment tank using a mixed-phase fluid of air and water as a coolant while transporting the steel wire rod on a conveyor. In this step, the refrigerant is maintained at a predetermined temperature of 80 to 95 ° C. by adjusting the wind speed to forcefully blow air onto the surface of the refrigerant, and adjusting the flow rate of gas that is supplied to form bubbles in the refrigerant to form bubbles. A method for direct heat treatment of a steel wire, characterized in that the heat treatment is performed using a steel wire rod. (2) Direct heat treatment of the steel wire rod, which is cooled by immersing the hot-rolled and non-concentrically rolled steel wire rod in a heat treatment tank using a steam-water multiphase fluid as a refrigerant while transporting the steel wire rod on a conveyor. A steel wire rod characterized in that the equipment is equipped with a means for controlling the wind speed and forcing air onto the surface of the refrigerant, and a means for adjusting the amount of gas supplied to the gas supply device that forms bubbles in the air-water multiphase fluid that is the refrigerant. direct heat treatment equipment.