KR920008695B1 - Method & device for making the p.c. steel pipe - Google Patents

Abstract

This method employs an equipment consisting of descaler (2), drawing machine (3), pre-heating coil (5), main heating coil (6), quenching bath (7), tempering heating coil (9), cooling bath (11), and coiler (13). In the method, tempering is in-lined, and a sequential high frequency heating equipment is divided to 3 parts for main heating and 2 parts for tempering. The pre-heating temperature is 700-750 deg.C, and the steel bar is water quenched after heating, of which temperature range is 850-950 deg.C. After that, the bar passed for the tempering process that the steel bar is heated over 2 times with frequency induction heating equipments at the moving speed of over 50 m/min.

Description

Manufacturing method and apparatus of high tensile tension release P.C steel wire

1 is a device explanatory diagram of the present invention.

2 is a relationship between the heating temperature and the heating coil arrangement.

3 is a relationship between the tampering temperature and the coil arrangement.

* Explanation of symbols for main parts of the drawings

1: supply table 2: descaler

3: drawing machine 5: preheating coil

6: main heating coil 7: immersion tank

9: tempering heating coil 11: cooling tank

13: winder

The present invention is a single heat treatment process (IN-LINE), but the sequential high frequency induction heating device is heated to three or more divided into two or more parts to heat the tempering to separate the heat flux (LINE SPEED) 50M / The present invention relates to a method for manufacturing a high tensile strain-released PC steel wire and a device thereof, which can significantly improve productivity by allowing heating above Min.

The manufacturing process of P.C bars used in centrifugal concrete piles, concrete poles or P.C concrete pipes is originally

Has been producing finished products in accordance with the process of Japanese Patent Publication No. 41-13363 and Japanese Patent No. 52-32450.

A method of manufacturing a continuous high-frequency heat treatment of a release P.C bar made of silver has been developed and is now widely used. However, this conventional method is to perform continuous high frequency heat treatment after freshly wired wire, which is not complicated and efficient, and the production cost is low due to productivity not exceeding 35M / Min based on PC bar ψ9,2mm. The rising problem is pointed out.

The present invention was devised in view of such a conventional problem, and adopts the IN-LINE SYSTEM of the device to shorten the process, and to increase the productivity by the high frequency induction heating equipment to increase the heating speed (° C / Sec) quickly Although there are difficulties due to the relationship between temperature control, productivity is improved by increasing the speed of the heating element.

Hereinafter, the apparatus of the present invention will be described with reference to FIG. 1.

The hot rolled steel is passed through the supply base (1) to remove the scale through the mechanical scale remover (2), and then fed to the drawing machine (3) to make a round or shaped drawing, and then divided into three parts with the preheating coil (5). When the high-frequency induction heating is performed at a temperature in the range of 980 ° C. in which the austenitic structure can be formed in the main heating coil 6 partitioned above, the spray water quenching (WATER QUENCHING) of the high pressure in the immersion tank 7, The tempered heating coil 9 is also divided into two or more portions of the quenched material, and the carbon content is 0.27-0.35%. The coil was wound in the form of 13), and the guides (4) were installed in various places to prevent vibration or detachment of the wire rod generated during high speed operation, and the installation of the automatic cutting machine 12 was performed at a predetermined length. Production will be completed For automatic cutting, the chemstan (b) of the drawing machine is used to adjust the linear speed of the device to facilitate constant speed operation, and to make the heating temperature of the material even at high speed by constant speed operation. Can be. The driving of the drawing machine 3 causes constant speed operation with a constant output DC motor, and tensions between the pinch rolls 8 and 10 before and after the tempering heating coil 9 to straighten the steel that passes the heating coil. By doing so, it is possible to improve the linearity at the time of heating and water quenching and at the same time prevent the risk of contacting the coil while sagging down by heat softening. In addition, between the feeder 1 and the drawing machine 3, a straightening roll and a drawing die box (a) are installed on the frame of the drawing machine so that the die for forming can be used, and a deforming roll is installed after the die box. In this way, it is possible to process the material surface shape that can meet the needs of the recipient.

An embodiment using the present apparatus as described above will be described.

EXAMPLE

As a test material of this example, AISI 1030B having the components shown in Table 1 was used.

TABLE 1

As shown in FIG. 2, the heating coil 6 is equally divided into three or more portions, and the preheating coil 5 is heated to a temperature of 700-750 ° C. in the transformation point range at a medium frequency of 10 KHz or less. High frequency induction heating of 200KHz, heating and passing repeatedly to 850-950 ° C after heating the steel so that the steel can sufficiently form austenite structure to the center of steel even when moving at a linear speed of 50M / MIN or more. By quenching the water, the quenching step was completed.

At this time, the heat treatment liquid may be diluted slightly in the cooling water, and it can be seen that the temperature of the center of the material is easily heated to the same temperature of the outer layer by the installation state of the main heating coil as described above, and the danger of overheating is prevented. Power savings could be achieved.

In addition, in raising the linear velocity, as shown in Table 2, it was found that the steel can be accelerated by appropriately combining the heating time by selecting the frequency, the length of the heating coil, and the arrangement of the coils according to the line drawing.

TABLE 2

In order to confirm the above results, the hardness measurement on the right angle cross section of the steel showed surface: 53HRc, 1.5mm depth: 53HRc, 3mm depth: 52HRc, 4,55mm depth: 51HRc.

Medium frequency induction heating of 400 ± 20 ° C was performed on the tempering heating coil with the material subjected to the above quenching process, and the tempering heating coil was also divided into two or more equal parts of the heating coil as shown in the third dome. By heating the material at a moving speed of 50M / MIN or higher at a speed of less than 100 ° C / Sec, a high-quality high-strength PC steel wire having mechanical properties as shown in Table 3 below KS D3505 SBPD135 / 145 and JIS G 3109 SBPD 135/145 is obtained. Could get

TABLE 3

Here, whether or not cooling after tempering does not have much relation to the characteristics of the product, but it is also preferable to cool the water in consideration of the safety of the worker's burn.

A feature of the present invention is to raise the speed of the heating element even though the heating rate (° C./SEC) may be increased even by improving the productivity by the high frequency induction heating equipment.

Rapid v = h × 1 (θ2-θ1) 60 ℃ / sec of blast furnace steel

t: time (sec), 1: length of coil, v: flux (m / min), h: heating rate (° C / sec) θ1: preheating temperature (° C), θ2: temperature after heating (° C)

Claims (2)

When manufacturing a deformed PC steel wire from structural carbon steel, preheating is performed at 700-750 ℃ before and after austenite transformation point as a medium frequency induction heating device, and the high frequency induction heating apparatus after transformation point is evenly divided by at least 3 parts and the steel is 50M. Heater is quenched after continuous heating in the range of 850-950 ℃ at a moving speed of over / MIN, and heated twice or more times in an induction heating device with a frequency of 10KHz or less, and the wire is tempered at a moving speed of 50M / MIN or higher. Method of manufacturing tensile tension release PC steel wire. In general, separate wire drawing process is performed with heat treatment process (IN LINE), but the preheating device is installed with a preliminary medium frequency induction heating device before the austenite transformation point, and after the transformation point, the high frequency induction heating coil is equally divided into three or more parts. An apparatus for manufacturing a high tensile strain-type PC steel wire, characterized by a structure in which two or more arranged induction heating devices for tempering are installed so that the material is heated and tempered at a heating speed and a moving speed of 50 M / MIN or more.