Disclosure of Invention
In view of the above, the present invention is directed to a method for cooling a small-caliber thick-walled steel pipe after rolling, so as to improve the cooling efficiency of the small-caliber thick-walled steel pipe after rolling.
In order to achieve the purpose, the invention provides the following technical scheme:
a cooling method for a small-caliber thick-wall steel pipe after rolling comprises the following process steps:
heating: heating and preserving heat of the steel billet, wherein the temperature difference between the surface of a billet core and the temperature difference between the head and the tail of the billet is not more than a ℃ after heating and preserving heat;
perforating: removing oxide scales on the surface of the heated billet, piercing and rolling the billet into a hollow billet, and removing the billet which does not meet the rolling requirement;
removing iron oxide scales on the inner surface of the capillary;
rolling a continuous rolled pipe: the mandrel is penetrated into the hollow billet, and the cat butler and the mandrel perform continuous rolling;
pipe removal: separating the rolled pierced billet inner core rod and recycling the core rod;
reducing and rolling: carrying out reducing rolling after removing phosphorus by high-pressure water and induction heat supplementation, wherein a rolling pass adopts a multi-section arc pass system and simultaneously adopts micro-tension rolling;
and (3) controlling cooling: the steel pipe after reducing is controlled and cooled by adopting a plurality of groups of annular gap nozzles so as to control the austenite structure after rolling;
cooling by spraying water on a cooling bed: cooling mechanisms are arranged above and below the cooling bed, and the steel pipe after controlled cooling passes through the cooling mechanism above the cooling bed and the cooling mechanism below the cooling bed, so that the controlled cooling of the steel pipe on the cooling bed is realized, and the steel pipe is ensured to obtain a project organization after rolling;
compressed air purging: and blowing compressed air to the cooled steel pipe to ensure no residual water and prevent red rust.
Optionally, in the step of heating, the heating temperature of the steel billet is 980-1180 ℃.
Optionally, in the step of heating, the temperature difference between the surface and the head and the tail of the billet core after heating and heat preservation is not more than 25 ℃.
Optionally, nitrogen and borax are sprayed into the capillary to remove iron oxide scales on the inner surface of the capillary.
Optionally, in the step of heating, the outer diameter of the billet is phi 150 mm; after the step of punching, the outer diameter of the capillary is phi 158mm, and the wall thickness is 12.2 mm; after the step of rolling the continuous rolled pipe, the outer diameter of the steel pipe is phi 120mm, and the wall thickness is 4.0 mm; after the step of reducing rolling, the outer diameter of the steel pipe is phi 42.42mm, and the wall thickness is 3.54 mm.
Optionally, in the step of piercing, the temperature of the billet is 980-1180 ℃.
Optionally, in the step of reducing rolling, the rolling temperature is 850-1020 ℃.
Optionally, in the step of reducing rolling and the step of cooling bed water spray cooling, the steel pipe is supported by the rotating mechanism, so that the steel pipe is uniformly cooled at different positions.
Optionally, after the compressed air is blown, the steel pipes are sequentially subjected to group arrangement, material distribution, head cutting, tail cutting and sizing, and then enter subsequent collection treatment.
Optionally, the step of cooling bed water spray cooling adopts a stepping cooling bed structure.
The invention has the beneficial effects that:
according to the invention, high-precision rolling of the steel pipe is realized through the high-pressure water descaling device before reducing and the four-roller or three-roller reducing unit, the product has high dimensional precision and small head-tail dimensional deviation; the problem of a cooling bed on a rolled piece is controlled through the cooling device after reducing, and head and tail bending is reduced; the phenomenon of coarse grains generated by high temperature after rolling is reduced; the steel pipe is uniformly cooled through the cooling bed stepping structure, the cooling mechanism above the cooling bed, the cooling mechanism below the cooling bed and the rotating mechanism, so that the cooling efficiency in the cooling bed is improved; by controlling the tissue transformation, an ideal uniform tissue is obtained, and finally a product with high uniform tissue and high stable mechanical property is obtained; the production stability is improved, the surface quality of the product is improved, the yield is improved, and the economic benefit is improved. The downstream process heat treatment cost can be reduced. The product has wide production specification range, and the production specification range can be 32 mm-127 mm in outer diameter; all products with the wall thickness of 3.5 mm-16 mm;
additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.
Referring to fig. 1 to 4, the present invention relates to a cooling method after rolling of a small-caliber thick-wall steel pipe, wherein one specific example is as follows:
1) a walking beam type annular heating furnace 1 is adopted to heat and preserve heat of the steel billet.
2) And taking the heated and heat-preserved billet out of the furnace by using a discharging machine, removing surface iron oxide scales, and conveying to a piercing mill 2 for piercing and rolling into a capillary.
3) The perforated capillary is sent to a blowing and brushing station 3 by a quick traversing device, and nitrogen and borax are blown into the capillary by a nozzle to remove the scale on the inner surface of the capillary, prevent the inner surface of the capillary from generating secondary oxidation and improve the lubricating effect of the inner surface.
4) Rolling with a continuous tube mill 5
And (3) transversely moving the capillary blown with nitrogen and borax in the step 3) to the front stage of a continuous tube rolling mill 5 by a quick transverse moving device. And the mandrel retaining system penetrates the mandrel into the hollow billet and sends the front end of the mandrel to the preset position of the continuous tube rolling mill 5, and the hollow billet and the mandrel enter the continuous tube rolling mill 5 for rolling. A high-pressure water descaling device is arranged at the inlet of the pipe mill 5 and is used for removing the scale on the outer surface of the hollow billet,
5) the pierced billets rolled by the continuous tube rolling mill 5 directly enter the 3-frame tube removing mill 6 for tube removing, and meanwhile, the core rods return to the front stage.
6) The pierced billet after being taken off by the 3-frame pipe-taking-off machine 6 enters a 24-frame three-roller or four-roller reducing mill 9 for rolling after high-pressure water descaling and induction heat supplementing, the rolling pass adopts a multi-section circular pass system, and simultaneously micro-tension rolling is adopted to ensure the dimensional precision after rolling and reduce the length of the head and the tail of the cut, and the rolling temperature is 850-1020 ℃.
7) And (3) performing controlled cooling on the steel pipe 15 rolled by the reducing unit 9, wherein the controlled cooling adopts a plurality of groups of annular gap nozzles to perform controlled cooling on the steel pipe 15 after being reduced so as to control the austenite structure after rolling.
8) The steel pipe is conveyed to a stepping type cooling bed 11 for cooling through a conveying roller way and a feeding device, controlled cooling of the steel pipe 15 on the cooling bed is realized through a cooling mechanism above the cooling bed and a cooling mechanism below the cooling bed, a project organization is ensured to be obtained after rolling, and a rotating mechanism is adopted to ensure that cooling can be realized at different positions of a rolled piece so as to improve the organization uniformity;
9) the steel pipe 15 after controlled cooling is blown with compressed air to ensure no residual water to prevent red rust.
10) The steel pipes 15 cooled by the cooling bed are sequentially arranged in rows and distributed, and then are sent to a row of cold saws by a conveying roller way to be cut at the head, cut at the tail and cut to length, and then are subjected to subsequent collection treatment.
The production process sequence of the invention comprises: heating, perforating, blowing nitrogen and borax into the interior of a hollow billet, removing scale by high-pressure water before continuous rolling, rolling by a continuous pipe rolling mill 5, removing the pipe, induction heating, removing the scale by the high-pressure water before reducing, rolling by a four-roller reducing unit 9, controlling cooling after rolling, spraying water to cool a cooling bed, blowing compressed air of the cooling bed, arranging the components, distributing the materials, cutting the head and the tail, sizing, collecting and finishing. Taking the production of a 40Cr steel pipe 15 with an outer diameter of 42mm and a wall thickness of 3.5mm as an example, the process is as follows:
1) heating by Ring furnace 1
The cut phi 150mm steel billet is heated to 980-1180 ℃ by adopting a walking beam type annular heating furnace 1, and heat preservation is carried out, wherein the temperature difference between the core surface and the head and tail of the heated and heat preserved steel billet is not more than 25 ℃.
2) Perforation
Taking the billet subjected to heating and heat preservation in the step 1) out of the furnace by using a discharging machine, removing surface iron oxide scales, and then sending the billet to a puncher 2 for piercing and rolling into a capillary, wherein the outer diameter of the perforated capillary is phi 158mm, and the wall thickness of the perforated capillary is 12.2 mm; when in piercing, the temperature of the billet is 980-1180 ℃, and the billet which does not meet the rolling temperature requirement or can not be rolled due to other reasons is stirred into a removing device for collection.
3) Blowing nitrogen and borax in the hollow billet
And (3) conveying the perforated capillary in the step 2) to a blowing and brushing station 3 by a quick transverse moving device, and blowing nitrogen and borax into the capillary by using a nozzle to remove oxide scales on the inner surface of the capillary, prevent the inner surface of the capillary from generating secondary oxidation and improve the lubricating effect of the inner surface.
4) Rolling with a continuous tube mill 5
And (3) transversely moving the capillary blown with nitrogen and borax in the step 3) to the front stage of a continuous tube rolling mill 5 by a quick transverse moving device. And the mandrel retaining system penetrates the mandrel into the hollow billet and sends the front end of the mandrel to the preset position of the continuous tube rolling mill 5, and the hollow billet and the mandrel enter the continuous tube rolling mill 5 for rolling. And a high-pressure water descaling device is arranged at the inlet of the pipe rolling mill 5 and is used for removing scale on the outer surface of the hollow billet, the outer diameter of the continuously rolled steel pipe 15 is phi 120mm, and the wall thickness is 4.0 mm.
5) Pipe-removing device
And (3) directly feeding the pierced billets rolled by the continuous tube rolling mill 5 in the step 4) into a rack tube removing machine 6 for tube removing, and simultaneously returning the core rods to the front stage.
6) Rolling by three-roller or four-roller reducing mill 9
And (3) carrying out high-pressure water descaling and induction heat supplementing on the pierced billets subjected to the tube removing by the 3-frame tube removing machine 6 in the step 5), then, rolling the pierced billets in a 24-frame three-roll or four-roll reducing unit 9, wherein the rolling pass adopts a multi-section circular-arc pass system, and simultaneously, micro-tension rolling is adopted to ensure the dimensional precision after rolling and reduce the length of the head and the tail of the cut, the rolling temperature is 850-1020 ℃, and after the rolling is finished, the outer diameter of the steel tube 15 is phi 42.42mm, and the wall thickness is 3.54 mm.
7) Post-reduction controlled cooling
And (3) performing controlled cooling on the steel pipe 15 rolled by the 24-frame three-roller or four-roller reducing mill 9 in the step 6), and performing controlled cooling on the reduced steel pipe 15 by adopting a plurality of groups of annular gap nozzles to control the rolled austenite structure.
8) Cooling bed water spray cooling
The steel pipe 15 after controlled cooling in the step 7) is conveyed to a stepping type cooling bed 11 through a conveying roller way and a feeding device for cooling, controlled cooling of the steel pipe 15 on the cooling bed is realized through a cooling mechanism above the cooling bed and a cooling mechanism below the cooling bed, a project organization is ensured to be obtained after rolling, and a rotating mechanism is adopted to ensure that cooling can be realized at different positions of a rolled piece so as to improve the organization uniformity;
9) cold bed compressed air purging
Blowing compressed air to the steel pipe 15 which is subjected to the controlled cooling in the step 8) to ensure that no residual water exists so as to prevent red rust.
10) Collecting by arranging, separating, cutting head and tail, sizing, etc
And (3) sequentially carrying out group arrangement and material distribution on the steel pipes 15 cooled by the cooling bed in the step 9), then conveying the steel pipes to a row of cold saws by a conveying roller way for head cutting, tail cutting and sizing, and carrying out subsequent collection treatment.
The equipment adopted by the invention is a cooling device for a small-caliber thick-wall steel pipe after rolling, which comprises an annular heating furnace 1, a piercing mill 2, a blowing and brushing station 3, a continuous pipe rolling mill 5, a pipe removing mill 6, an induction heating device 7, a reducing unit 9, a cooling device 10 after reducing, a stepping cooling bed 11 and a collecting and finishing system 14 which are linearly arranged in sequence.
Optionally, a high-pressure water dephosphorization device 4 before continuous rolling is arranged between the blowing and brushing station 3 and the continuous pipe rolling mill 5; a high-pressure water dephosphorization device 8 before reducing is arranged between the induction heating device 7 and the reducing unit 9; an upper cooling mechanism and a lower cooling mechanism 12 are arranged on the stepping cooling bed 11; a compressed air cleaning device 13 is arranged on the stepping cooling bed 11; the cooling device 10 after reducing comprises a water tank support 102, a water inlet pipeline 101 arranged on the water tank support 102 and a spray ring 103 communicated with the water inlet pipeline 101, wherein a cooling area for passing through a steel pipe 15 is formed in the spray ring 103, and a plurality of spray holes are formed in the spray ring 103.
Specifically, the main structure of the stepping cooling bed 11 is a stepping beam; the walking beam is provided with a water-cooling water tank 1101 and a water tank nozzle 1102 communicated with the water-cooling water tank 1101; and a main pipeline of the blowing nozzle 1103 and the blowing nozzle 1103 communicated with the main pipeline are arranged on the walking beam.
The invention has the following advantages:
1) high-precision rolling of the steel pipe 15 is realized through the high-pressure water descaling device before reducing and the four-roller or three-roller reducing unit 9, the product has high dimensional precision and small head-tail dimensional deviation;
2) the problem of a cooling bed on a rolled piece is controlled through the cooling device 10 after reducing, and head and tail bending is reduced;
3) the phenomenon of coarse grains generated by high temperature after rolling is reduced;
4) the steel pipe 15 is uniformly cooled through the cooling bed stepping structure, the cooling mechanism above the cooling bed, the cooling mechanism below the cooling bed and the rotating mechanism, so that the cooling efficiency in the cooling bed is improved;
5) by controlling the tissue transformation, an ideal uniform tissue is obtained, and finally a product with high uniform tissue and high stable mechanical property is obtained;
6) the product has wide production specification range, and the production specification range can be 32 mm-127 mm in outer diameter; all products with the wall thickness of 3.5 mm-16 mm;
7) the production stability is improved, the surface quality of the product is improved, the yield is improved, and the economic benefit is improved.
8) The downstream process heat treatment cost can be reduced.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.