JPH06346152A - Lead patenting apparatus for high carbon steel wire - Google Patents

Abstract

PURPOSE:To produce a steel wire having high strength and high ductility by separately controlling a cooling velocity and a holding temp. of the steel wire at the time of executing a lead patenting treatment before wire drawing process in the production of the steel wire. CONSTITUTION:The high carbon steel wire 2 uncoiled from a pay-off reel 1 is introduced into a heating furnace 3 and heated at 850-1000 deg.C, and after austenizing the structure, by passing the steel wire into a lead bath vessel 4 incorporated with the molten lead at about 600 deg.C, the lead patenting treatment is executed to the steel wire 2 and the steel wire is coiled in a coiler 5. In the lead bath vessel 4, plural quenching chambers composed of a first quenching chamber 6, second quenching chamber 7, etc., are arranged and the molten lead in the lead bath vessel 4 is sucked up with a circulating pump 8 and cooled by passing into a cooler 10 using the water as cooling medium to about 400-500 deg.C and supplied to both quenching chambers 6, 7 to rapidly cool the steel wire, and thereafter, the steel wire is passed in the lead bath at 600 deg.C and taken out to the outer part. In this case, the temp. of the sucked up molten lead is measured with a thermometer 13, and by adjusting the opening degree of a flow rate control valve 11 for cooling water with a temp. controller 12, the temp. of the molten lead is suitably controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a high cooling rate and a constant temperature during the heat treatment, which is a so-called patenting treatment, which is carried out before the wire drawing step in the production of a steel wire such as a cord wire used as a reinforcing material for automobile tires. The present invention relates to a lead patenting device for high-carbon steel wire, which achieves high tensile strength of the steel wire after drawing.

[0002]

2. Description of the Related Art Conventionally, eutectoid steel having a carbon content of about 0.8% has been used for the production of cord wire, and so-called lead containing molten lead as a refrigerant is used for the patenting treatment prior to the wire drawing process. Patenting is common practice.

FIG. 6 is a view showing a typical conventional lead patenting equipment, in which a steel wire 2 sent from a payoff reel 1 is heated in a heating furnace 3 at a temperature of AC ₃ or higher, that is, usually 850.
After being heated to 1000 ° C. to be austenitized, it is immediately immersed in a lead bath 4 kept at a constant temperature, for example, 600 ° C., cooled and held, and then the treated steel wire 2 is wound by a coiler.

The heat pattern in this patenting process is as shown in FIG. 3 as a representative, and the factors relating to the control of the structure and characteristics of steel are the cooling rate and the holding temperature in the heat pattern.

[0005]

However, in the above-mentioned conventional equipment, both the cooling rate and the holding temperature change in tandem by changing the temperature of the lead bath. You have to lower the temperature,
The cooling rate and holding temperature cannot be controlled individually.

By the way, recently, there is an increasing demand for higher tensile strength of the cord wire, and hypereutectoidization is one of the concrete methods for realizing the higher tensile strength of the cord wire. For wires obtained after wire drawing, such as steel cords, a method of improving the strength before wire drawing and the wire drawing workability is adopted in order to improve the strength. In addition to improving the strength before wire drawing, the strength increase (work hardening amount) due to wire drawing also increases.

However, in order to sufficiently bring out such properties of the hyper-eutectoid steel, it is necessary to increase the cooling rate as much as possible to suppress the precipitation of pro-eutectoid cementite and to carry out the holding transformation at the target temperature. In the above conventional equipment, 1) suppression of proeutectoid cementite,
2) It is impossible to satisfy both the two requirements of preventing the formation of a low temperature transformation structure (bainite).

On the other hand, attempts have been made industrially to realize the treatment by isothermal transformation.
Japanese Patent No. 168230 discloses the use of a fluidized bed.

However, in the invention described in this publication, the wire diameter is
The target is 3.0 mm or less, and the heat pattern is limited, which is not versatile and has poor stability.

Therefore, the main object of the present invention is to suppress the pro-eutectoid cementite and to surely achieve the eutectoid transformation at the target temperature by enabling rapid cooling.

[0011]

In the lead patenting apparatus for heating a high carbon steel wire to austenite it and then cooling it through a lead bath, the above-mentioned problem is solved by: One or a plurality of quenching chambers that are substantially compartmentalized from the lead bath are provided at intervals in the flow direction of the steel wire,
The steel wire exiting the quenching chamber is configured to be passed through a lead bath for a predetermined distance, and a continuous lead supply system for the quenching chamber is provided.
This can be solved by providing a temperature control means for the lead supplied to the outside of the lead bath of this supply system so that the lead supplied to the quenching chamber will later flow into the lead bath.

[0012]

In the present invention, one or more quenching chambers that are substantially compartmentalized from the surrounding lead baths are provided on the inlet side of the lead bath, and a plurality of quenching chambers are provided at intervals in the flow direction of the steel wire. The ejected steel wire is configured to be passed through a lead bath for a predetermined distance, a continuous lead supply system for the quenching chamber is provided, and a temperature control means for the lead supplied to the outside of the lead bath of the supply system is provided. Therefore, by adjusting the lead temperature supplied by the temperature control means to a low level,
The steel wire can be rapidly cooled. In addition, the lead bath temperature is set and adjusted by the lead bath itself,
It is possible to surely cause the eutectoid transformation at the target temperature.

[0013]

The present invention will be described in more detail below with reference to the embodiments shown in the drawings. FIG. 1 is a schematic view of a lead patenting device according to the present invention, in which 1 is a payoff reel, 2 is a steel wire, 3 is a heating furnace, 4 is a lead bath, and 5 is a coiler. A first quenching nozzle 6 and a second quenching nozzle 7 are soaked in order on the inlet side of the steel wire 2 in the lead bath 4 so that the steel wire 2 sequentially passes through them. You can do it.

Molten lead in the lead bath 4 is sucked up by the circulation pumps 8 and 8 into the first quenching nozzle 6 and the second quenching nozzle 7, and the first quenching is performed through the supply systems 9 and 9, respectively. It is adapted to be supplied to the working nozzle 6 and the second quenching nozzle 7. First quenching nozzle 6 and second
An example of the structure of the quenching nozzle 7 is as shown in FIG. 2, in which a header chamber is provided between an outer cylinder and an inner cylinder having concentric cylindrical diameters.
The above-mentioned molten lead is supplied into the header chamber and is discharged from the discharge ports 6a, 6a ..., 7a, 7a. In this example, as shown in the drawing, the first quenching discharge ports 6a, 6a ... Are obliquely opened in the flow direction of the steel wire, and conversely, the discharge ports 7a, 7a. It opens diagonally to the upstream side.

On the other hand, the circulating supply systems 9 and 9 for molten lead are provided with a cooler 10 through which cooling water passes, and exchange heat with the heat of the cooling water in the process in which the molten lead passes through the supply systems 9 and 9. It is designed to be cooled.

On the other hand, 11 is a flow rate control valve for the cooling water supplied to the cooler 10, and based on the temperature signals from the supplied lead thermometers 13 and 13, the temperature controller 12 causes
The opening of the flow rate adjusting valve 11 is adjusted so that the supply lead has a target temperature.

The reason for arranging the first quenching nozzle 6 and the second quenching nozzle 7 by immersing them in the lead bath is as follows. That is, in order to perform the process in the isothermal transformation, it is necessary to immediately introduce the steel wire 2 into the lead bath maintained at a constant temperature after cooling to the target temperature.

In the above example, the first quenching nozzle 6 and the second quenching nozzle 7 constitute a quenching chamber which is substantially partitioned from the surrounding lead bath referred to in the present invention. It can be inferred that this modification of the quenching chamber can have an appropriate structure without departing from the spirit of the present invention.

(Experimental example) Next, the effect of the present invention will be clarified by an experimental example. Φ5 having the chemical components shown in Table 1.
Using a 5 mm wire rod as the material, φ1.2 in the manufacturing process shown in Fig. 4.
A mm-sized cord wire was prototyped.

[0020]

[Table 1]

For lead patenting, the apparatus shown in FIG. 6 was used as the conventional apparatus, while the apparatus shown in FIG. 1 was used as the apparatus of the present invention. Further, in the apparatus of FIG. 1, the first quenching nozzle 6 and the second quenching nozzle 7 each have a length of 1 m, and the lead bath 4 has a passage (immersion) length of 15 m. The running speed was 30 m / min. FIG. 5 shows a cooling pattern in patenting using the device of the present invention. In this experimental example, the first quenching nozzle 6 and the second quenching nozzle 6
Molten lead adjusted to 370 ° C. was flown into the quenching nozzle 7, the φ3.0 mm wire rod was cooled, and then introduced into a 600 ° C. lead bath. The experimental results are shown in Table 2.

[0022]

[Table 2]

As shown in Table 2, in the conventional apparatus, since pro-eutectoid cementite or bainite is generated to lower the wire drawing limit, the strength after wire drawing is around 3100 MPa and the drawing is 3
It was around 0%. On the other hand, in the device of the present invention, the occurrence of pro-eutectoid cementite and bainite are both prevented, and after the wire drawing, high strength of 4000 to 4190 MPa and
A wire having an aperture value of not less than% was obtained.

[0024]

As described above, according to the present invention, rapid cooling is possible, and the cooling rate and the holding temperature can be individually controlled, so that proeutectoid cementite and bainite are not generated, and The characteristics of eutectoid steel can be fully exploited, and thus a wire having high strength and high ductility can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a lead patenting treatment apparatus according to the present invention.

FIG. 2 is an enlarged vertical sectional view of the quenching nozzle shown in FIG.

FIG. 3 is a diagram showing a heat pattern control factor in patenting.

FIG. 4 is a diagram showing a manufacturing process in an experimental example.

FIG. 5 is a diagram showing a cooling pattern in patenting using the device of the present invention.

FIG. 6 is an explanatory diagram of a conventional lead patenting treatment method.

[Explanation of symbols]

1 ... Pay-off reel, 2 ... Steel wire, 3 ... Heating furnace, 4 ... Lead bath, 5 ... Coiler, 6 ... No. 1 quenching nozzle, 7 ... No. 2 quenching nozzle, 8 ... Circulation pump, 9 ... Melting Lead supply system, 10
... Cooler, 11 ... Flow rate adjusting valve, 12 ... Temperature controller, 13 ... Thermometer.

Claims (1)

[Claims] 1. A lead patenting apparatus in which a high carbon steel wire is heated to austenite and then cooled through a lead bath, wherein the lead bath is substantially separated from the surrounding lead bath at the inlet side. One quenching chamber is provided or a plurality of quenching chambers are provided at intervals in the flow direction of the steel wire, and the steel wire exiting the quenching chamber is passed through a lead bath for a predetermined distance. Is provided, and a means for adjusting the temperature of the lead supplied to the outside of the lead bath of the supply system is provided, and the lead supplied into the quenching chamber later flows out into the lead bath. Lead patenting device for high carbon steel wire.