RU2440427C1 - Rail manufacturing method - Google Patents

Abstract

FIELD: metallurgy. ^ SUBSTANCE: steel making, out-of-furnace steel treatment, continuous pouring on continuous casting machine, cooling of continuous cast steel billets, rolling, slow cooling after rolling, flattening and heat treatment is performed; at that, hydrogen content in liquid steel at pouring on continuous casting machine is not more than 1.5 ppm; cooling is performed after rolling in series in edgewise position and in pairs through the cooling plant in flow mode using air flow with flow rate of 60000 m3/h during 30-60 seconds; then, cooling is performed in "on foot" position on racks at natural air convection during 30-40 minutes and in "on foot" position using fans in order to provide the rail temperature of 80-100C. ^ EFFECT: shortening the cooling duration of rails, surface defects related to transportation operations; providing the required rail curvature. ^ 2 dwg

Description

The invention relates to ferrous metallurgy, in particular to the production of rails.

A known method of cooling the rails after rolling and cutting, including cooling on the refrigerators in the "lying on the side", while on the upper side surfaces of the rails at a length of 1 m from the end in the temperature range 600-800 ° C serves compressed air, water or steam -air mixture, after which with the help of magnetic taps the rails are transferred to the wells of slow cooling [1].

Significant disadvantages of this method are: the long duration of the cooling process of the rails, the high cost of maintaining the section of boxes of delayed cooling, the large curvature along the entire length of the rails, the large rejection of rails for surface defects due to transport operations.

There is also known a method of cooling the rails after rolling and cutting, including cooling in the refrigerator to a temperature of 530-550 ° C of rails laid closely in the "outsole" position on the insulated refrigerator, after which the rails are transferred to the slow cooling wells using magnetic taps [2] .

Significant disadvantages of this method are: the long duration of the cooling process of the rails, the high cost of maintaining the section of boxes of delayed cooling, the large curvature along the entire length of the rails, the large rejection of rails for surface defects due to transport operations.

There is also a method of cooling the rails after rolling and cutting, including cooling the rolling surface of the rail head on the refrigerator in the "on the side" position to a temperature of 900-1000 ° C for a length of 1 m from their ends by supplying compressed air with a flow rate of 10-35 m ³ / min at a pressure of 3-5 atm and a temperature of 10-30 ° C or water with a flow rate of 1-5 l / min and a temperature of 10-30 ° C for 1.5-2.5 minutes, after which the rails are transferred using magnetic taps in the box of delayed cooling [3].

Significant disadvantages of this method are: the long duration of the cooling process of the rails, the high cost of maintaining the section of boxes of delayed cooling, the large curvature along the entire length of the rails, the large rejection of rails for surface defects due to transport operations.

Known as a prototype method for the production of rails, including cooling the rails on the refrigerator in the "on the bottom" position close to each other to a temperature not lower than 350 ° C, followed by transportation and laying in boxes of slow cooling and holding them for 7.0 -7.5 hours [4].

Significant disadvantages of this method are: the long duration of the cooling process of the rails, the high cost of maintaining the section of boxes of delayed cooling, the large curvature along the entire length of the rails, the large rejection of rails for surface defects due to transport operations.

The desired technical results of the invention are:

1. The reduction in the cooling time of the rails.

2. Reduced costs in the production of rails by eliminating the cost of maintaining a section of boxes of delayed cooling.

3. Providing the required curvature of the rails.

4. Reduction of surface defects of rails associated with transport operations.

For this, a method for producing rails is proposed, including smelting, out-of-furnace treatment, continuous casting, cooling of continuously cast billets, rolling, delayed cooling, dressing and heat treatment, characterized in that the hydrogen content in the molten steel during casting on continuous casting machines provides no more than 1.5 ppm, the cooling after the rolling is carried out sequentially in the "on its side" in pairs through the apparatus to cool in the through mode with the use of air flow at a rate of 60,000 m ³ / h for 30-60 seconds, followed by cooling etc. lead in position "on the bottom" on the shelves with the natural convection air for 30-40 minutes and in the position "on the bottom" with the fans to provide rails temperature 80-100 ° C.

The inventive technology is selected experimentally on the basis of the following premises. When the hydrogen content in liquid steel is not more than 1.5 ppm, the formation of flocs does not occur and delayed cooling of the rolled products is not required. When the rails are cooled in pairs in the installation for less than 30 seconds, the rail does not have time to cool to the required temperature of 600 ° С, and the required rolling rate is not provided for the cooling time of more than 60 seconds. Air supply with a flow rate of less than 60,000 m ³ / h will not provide sufficient cooling of the rails; with an air flow of more than 60,000 m ³ / h, the rails will not uniformly cool down over the entire cross-section of the profile. Cooling for less than 30 minutes does not allow reaching the temperature necessary for high-quality straightening of the rails; cooling for more than 40 minutes does not provide the necessary rolling rate. Cooling to a temperature of more than 100 ° C does not provide for high-quality straightening of the rails, cooling to a temperature of less than 80 ° C does not provide the necessary rolling rate.

The inventive technology for the production of rails was tested in the manufacture of rails of the type P65, P50, OP65, OP50, UR65 in the conditions of the rail and beam workshop.

Rails with a hydrogen content in liquid steel of not more than 1.5 ppm, after rolling and cutting in pairs (1), were cooled in the “side” position for 30-60 seconds in a cooling unit (2) under the action of air flow directed along the rails provided by the operation of two axial fans (3) (figure 1). Then the rails were collected on racks in the “on the bottom” position in the amount of 60-70 pieces and cooled for 30 minutes with natural air convection, and then packets were formed by an electric bridge crane, laid out in specially designated places of 30-35 pieces (4) and cooled for 30-40 minutes by air flows created by axial fans (5) to the temperature of the dressing (figure 2).

The use of the claimed technology for the production of rails in the conditions of the rail and beam workshop allowed:

1. Reduce the cooling time of the rails from 8.5 hours to 1.5 hours

2. To reduce the cost of maintaining the section of boxes of delayed cooling by 9.5 million rubles / year.

3. Reduce the maximum curvature of the rails from 16 mm / m to 10 mm / m.

4. To reduce the formation of defects on the surface of rails from 0.05% of total production to 0.01%.

Information sources

1. Patent SU 227357. Published November 25, 68. A method for cooling rails after rolling and cutting.

2. Patent SU 218934. Published on 05/30/68. The method of cooling the rails after rolling.

3. Patent RU 2365637 C1. Published on August 27, 2009. A method for cooling rails after rolling and cutting.

4. Instruction of OJSC NKMK, TI 109-RB-057-2007. Production of rolled products in the rail and beam shop. Novokuznetsk, 2007, 95 p.

Claims (1)

A method for producing rails, including smelting, out-of-furnace steel processing, steel casting at continuous casting machines, cooling of continuously cast billets, rolling, delayed cooling after rolling, dressing and heat treatment, characterized in that the hydrogen content in molten steel during casting at continuous casting machines is no more than 1 , 5 ppm, and the cooling after rolling is carried out sequentially in the “on the side” position in pairs through the installation for cooling in a continuous mode using an air stream with a flow rate of 60,000 m ³ / h for 30-60 s, then cooling t in the "on the sole" position on the shelves with natural air convection for 30-40 minutes and in the "sole" position with the use of fans until the rails are at a temperature of 80-100 ° С.

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