CN114799095B - Reinforcement bar heating-free direct rolling method and reinforcement bar rolled by heating-free direct rolling method - Google Patents
Reinforcement bar heating-free direct rolling method and reinforcement bar rolled by heating-free direct rolling method Download PDFInfo
- Publication number
- CN114799095B CN114799095B CN202210471382.0A CN202210471382A CN114799095B CN 114799095 B CN114799095 B CN 114799095B CN 202210471382 A CN202210471382 A CN 202210471382A CN 114799095 B CN114799095 B CN 114799095B
- Authority
- CN
- China
- Prior art keywords
- temperature
- casting blank
- rolling
- head
- cooling control
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000005096 rolling process Methods 0.000 title claims abstract description 223
- 238000000034 method Methods 0.000 title claims abstract description 171
- 230000002787 reinforcement Effects 0.000 title claims description 5
- 238000005266 casting Methods 0.000 claims abstract description 198
- 230000008569 process Effects 0.000 claims abstract description 79
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 58
- 239000010959 steel Substances 0.000 claims abstract description 58
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 46
- 238000010008 shearing Methods 0.000 claims abstract description 26
- 238000009749 continuous casting Methods 0.000 claims abstract description 24
- 229910052742 iron Inorganic materials 0.000 claims abstract description 23
- 238000003723 Smelting Methods 0.000 claims abstract description 14
- 239000000126 substance Substances 0.000 claims abstract description 10
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 9
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 6
- 230000023556 desulfurization Effects 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 claims description 114
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 80
- 239000007921 spray Substances 0.000 claims description 71
- 238000009529 body temperature measurement Methods 0.000 claims description 35
- 238000004513 sizing Methods 0.000 claims description 27
- 238000005507 spraying Methods 0.000 claims description 22
- 238000010438 heat treatment Methods 0.000 claims description 20
- 238000005259 measurement Methods 0.000 claims description 17
- 230000009471 action Effects 0.000 claims description 10
- 230000000149 penetrating effect Effects 0.000 claims description 6
- 238000005520 cutting process Methods 0.000 claims description 5
- 238000013208 measuring procedure Methods 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 description 10
- 238000004321 preservation Methods 0.000 description 10
- 239000002893 slag Substances 0.000 description 10
- 239000000463 material Substances 0.000 description 7
- 238000010079 rubber tapping Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 238000005728 strengthening Methods 0.000 description 6
- 230000008859 change Effects 0.000 description 5
- 238000013461 design Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000001681 protective effect Effects 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 238000004781 supercooling Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 238000003331 infrared imaging Methods 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 238000001953 recrystallisation Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000013507 mapping Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000006748 scratching Methods 0.000 description 1
- 230000002393 scratching effect Effects 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
- B21B1/18—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section in a continuous process
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/12—Accessories for subsequent treating or working cast stock in situ
- B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/12—Accessories for subsequent treating or working cast stock in situ
- B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
- B22D11/1246—Nozzles; Spray heads
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/12—Accessories for subsequent treating or working cast stock in situ
- B22D11/126—Accessories for subsequent treating or working cast stock in situ for cutting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/163—Controlling or regulating processes or operations for cutting cast stock
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
- B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
- C22C33/06—Making ferrous alloys by melting using master alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
Abstract
The embodiment of the invention provides a steel bar heating-free direct rolling method and a steel bar rolled by the heating-free direct rolling method, comprising the following steps: sequentially carrying out the working procedures of blast furnace molten iron smelting, molten iron desulfurization pretreatment, converter molten steel smelting, billet continuous casting, hot continuous rolling and fixed-length shearing; in the square billet continuous casting process, controlling the difference value between the head temperature and the tail temperature of a casting blank to be 20-40 ℃; in the hot continuous rolling process, the difference between the head temperature and the tail temperature of the rolled piece is controlled to be 20-30 ℃. According to the technical scheme, the temperature difference between the head and the tail of the steel bar obtained by adopting the heating-free direct rolling process can be controlled within a reasonable range, and the problem of poor consistency of the strength of the head and the tail caused by overlarge temperature difference between the head and the tail is solved. The steel bar rolled by the heating-free direct rolling method comprises the following chemical components in percentage by weight: c:0.23wt%, si:0.50wt%, mn:1.19wt%, P:0.030wt%, S:0.026wt%, nb:0.002Wt%, ti:0.002Wt%, alt:0.0019wt%, V:0.026wt%, N:0.0075Wt%.
Description
Technical Field
The invention relates to the technical field of steel production, in particular to a steel bar heating-free direct rolling method and a steel bar rolled by the heating-free direct rolling method.
Background
The billet heating-free direct rolling becomes the development direction of the current rod and wire production, and in the process, a casting blank can directly enter a rolling mill for rolling without being reheated by a heating furnace, so that the efficiency is improved, and the production cost is reduced.
In the process of implementing the present invention, the inventor finds that at least the following problems exist in the prior art:
because the casting blank directly rolled is not reheated by the heating furnace, the head part of the casting blank is produced in the continuous casting machine and the tail part of the casting blank is produced after the head part is produced, the temperature of the head part and the tail part of the casting blank are low, and the mechanical strength of the head part and the tail part of rolled steel are high and the strength of the tail part is low, so that the quality stability of a product is influenced. Therefore, how to control the temperature difference between the head and the tail of the steel bar in a reasonable range in the square billet heating-free direct rolling so as to keep the mechanical properties of the head and the tail of the final finished product stable is a problem to be solved.
Disclosure of Invention
The embodiment of the invention provides a heating-free direct rolling method for reinforcing steel bars, which aims to solve the problem that the existing reinforcing steel bar finished product obtained by adopting a heating-free direct rolling mode has larger difference in mechanical strength between the head and the tail.
In order to achieve the above object, an embodiment of the present invention provides a method for directly rolling a steel bar without heating, including:
sequentially carrying out the working procedures of blast furnace molten iron smelting, molten iron desulfurization pretreatment, converter molten steel smelting, billet continuous casting, hot continuous rolling and fixed-length shearing;
wherein, the blank heating procedure between the continuous casting of the square billet and the hot continuous rolling is removed;
in the square billet continuous casting process, controlling the difference value between the head temperature and the tail temperature of a casting blank to be 20-40 ℃;
in the hot continuous rolling process, the difference between the head temperature and the tail temperature of the rolled piece is controlled to be 20-30 ℃.
Further, before the blast furnace molten iron smelting process, the method further comprises:
the chemical components and weight percentages of the steel bars are determined as follows: c:0.20 to 0.25Wt percent, si:0.40 to 0.55Wt percent, mn:1.10 to 1.25Wt percent, P: less than or equal to 0.045wt%, S: less than or equal to 0.045wt%, nb: less than or equal to 0.004Wt percent, ti: less than or equal to 0.007wt%, alt: less than or equal to 0.006wt%, V:0.02 to 0.03Wt percent, N: 0.005-0.011 wt%.
Further, the steel bars comprise the following chemical components in percentage by weight: c:0.23wt%, si:0.50wt%, mn:1.19wt%, P:0.030wt%, S:0.026wt%, nb:0.002Wt%, ti:0.002Wt%, alt:0.0019wt%, V:0.026wt%, N:0.0075Wt%.
Further, the difference between the temperature of the head and the temperature of the tail of the casting blank is controlled to be 20-40 ℃, and the method specifically comprises the following steps:
setting a casting blank fixed-length shearing procedure in the square billet continuous casting procedure;
the casting blank fixed-length shearing process is completed by adopting hydraulic shearing; the casting blank fixed-length shearing process specifically comprises the following steps:
a contact type sizing device is arranged on the blank feeding roller way at a preset distance from the hydraulic shears;
when the head of the casting blank contacts the contact type sizing device, the contact type sizing device outputs a shearing action signal to the control system;
the control system sends an action command to the hydraulic shear;
the hydraulic shears cut off the casting blank according to the action instruction.
Further, the difference between the temperature of the head and the temperature of the tail of the casting blank is controlled to be 20-40 ℃, and the method further comprises the following steps:
setting an oxide scale removing process, a measuring process and a casting blank cooling control process after the casting blank sizing and shearing process; wherein,
in the step of removing the oxide skin, the oxide skin on the side surface of the casting blank is removed through a steel wire brush;
in the measuring procedure, the temperature of the side surface of the casting blank from which the oxide skin is removed is recorded and measured according to a preset time interval by a pyrometer, and a casting blank temperature curve is generated according to the measuring result, wherein the casting blank temperature curve is used for reflecting the temperature difference of different positions from the head part to the tail part of the casting blank;
and (5) completing the casting blank cooling control process according to the casting blank temperature curve.
Further, the casting blank cooling control process is completed according to a casting blank temperature curve, and specifically comprises the following steps:
determining a starting position which is 20 ℃ higher than the temperature of the head of the casting blank on the casting blank according to the temperature curve of the casting blank;
spraying water to the part behind the initial position on the casting blank through casting blank cooling control spray heads respectively arranged at the upper left, lower right and upper right of the outer side of the casting blank;
and adjusting the water spraying intensity of each casting blank cooling control spray head in real time according to the casting blank temperature curve and the moving speed of the casting blank.
Further, the difference between the head temperature and the tail temperature of the rolled piece is controlled to be 20-30 ℃, and the method specifically comprises the following steps:
the hot continuous rolling process is provided with the working procedures of rough rolling, rough rolling cooling control, middle rolling cooling control, finish rolling and finish rolling cooling control in sequence;
the method comprises the steps of performing temperature measurement in a rough rolling procedure, and generating a first temperature curve according to a measurement result;
the rough rolling and cooling control process specifically comprises the following steps:
a water spray head is arranged on the outer side of the rolled piece;
selecting a water spraying starting position on a rolled piece;
spraying water to a part behind a water spraying starting position on the rolled piece through a water spray nozzle;
and adjusting the water spraying intensity of each water spray head in real time according to the first temperature curve.
Further, the difference between the head temperature and the tail temperature of the rolled piece is controlled to be 20 ℃ to 30 ℃, and the method further comprises the following steps:
temperature measurement is carried out in the middle rolling procedure, and a second temperature curve is generated according to the measurement result;
the middle rolling cooling control procedure adopts a water penetrating device to adjust the temperature of a rolled piece, and adjusts the cooling control intensity of the middle rolling cooling control procedure in real time according to a second temperature curve;
temperature measurement is carried out in the finish rolling process, and a third temperature curve is generated according to the measurement result;
the finish rolling cooling control procedure adopts a multi-stage cooling controller to adjust the temperature of the rolled piece, and adjusts the cooling control intensity of the finish rolling cooling control procedure in real time according to a third temperature curve.
Further, after the finish rolling and cooling control process, the method further comprises the following steps:
temperature measurement after finish rolling and cold control process after finish rolling;
the temperature measurement is carried out in the temperature measurement process after finish rolling, and a fourth temperature curve is generated according to the measurement result;
the temperature of the rolled piece is adjusted by adopting a multi-stage cold controller in the cold control process after finish rolling, and the cold control intensity in the cold control process after finish rolling is adjusted in real time according to a fourth temperature curve.
Further, the method also comprises a pre-finish rolling and pre-finish rolling cooling control process before the finish rolling process;
the method comprises the steps of performing temperature measurement in a pre-finish rolling process, and generating a fifth temperature curve according to a measurement result;
the pre-finish rolling cooling control procedure adopts a multi-stage nozzle to adjust the temperature of the rolled piece, and adjusts the cooling control intensity of the pre-finish rolling cooling control procedure in real time according to a fifth temperature curve.
The invention also provides a steel bar rolled by the heating-free direct rolling method, which comprises the following chemical components in percentage by weight: c:0.20 to 0.25Wt percent, si:0.40 to 0.55Wt percent, mn:1.10 to 1.25Wt percent, P: less than or equal to 0.045wt%, S: less than or equal to 0.045wt%, nb: less than or equal to 0.004Wt percent, ti: less than or equal to 0.007wt%, alt: less than or equal to 0.006wt%, V:0.02 to 0.03Wt percent, N: 0.005-0.011 wt%, and adopting the steel bar heating-free direct rolling method.
Further, the steel bars comprise the following chemical components in percentage by weight: c:0.23wt%, si:0.50wt%, mn:1.19wt%, P:0.030wt%, S:0.026wt%, nb:0.002Wt%, ti:0.002Wt%, alt:0.0019wt%, V:0.026wt%, N:0.0075Wt%.
Further, the steel bars are HRB400E anti-seismic steel bars.
Further, the specification of the steel bar is phi 12-40mm.
Further, the specification of the steel bar is phi 28mm.
Further, the steel bar is formed by rolling a casting blank with a section of 165mm multiplied by 165mm and a length of 11 m.
The technical scheme has the following beneficial effects:
in the technical scheme of the invention, the temperature difference between the head and the tail of the steel bar is adjusted by a multi-layer temperature control means: 1. the contact type mechanical sizing device with simple and reliable structure is matched with hydraulic shear operation, so that casting blanks can be cut off rapidly, and waiting time and temperature drop are reduced; 2. the method comprises the steps of measuring the surface temperature of a casting blank and forming a temperature trend line, and adjusting the water spray intensity of each casting blank cooling control spray head in real time according to the temperature trend line, so that the rear section of the casting blank is cooled in the way, and the temperature difference between the head and the tail of the casting blank before entering a rolling mill is controlled within a reasonable range; 3. a multi-layer cooling control device is arranged in the rolling process, particularly a unique water spray head is designed in a rough rolling section, all cooling control procedures take a measured temperature trend line as a reference, real-time adjustment of temperature control at different positions on a rolled piece is realized, and head-tail temperature difference of the rolled piece is effectively reduced. The adoption of the technical means ensures that the strength difference of the head and the tail of the final finished product is controlled within a reasonable range, and the quality stability of the product is greatly improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a flowchart of a method for directly rolling a reinforcing bar without heating according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the apparatus for descaling, casting blank temperature measurement and casting blank cooling control in the square billet continuous casting process according to the embodiment of the invention;
FIG. 3 is a schematic diagram of a casting blank cooling control spray head arrangement in an embodiment of the invention;
fig. 4 is a schematic view of an injection protection range of a casting blank cooling control nozzle (a view in a direction a in fig. 2) according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a spray hole structure of a casting blank cooling control spray nozzle in an embodiment of the invention;
fig. 6 is a schematic structural view of a contact sizing device in a square billet continuous casting process in an embodiment of the present invention;
reference numerals: 1. casting blank; 11. a corner; 2. a special heat-insulating cover; 3. a blank feeding roller way; 31. a blank feeding roller way side plate; 4. A casting blank cooling control spray head; 41. a spray hole; 42. a rectangular water spray coverage area; 5. a pyrometer; 6. a control system; 7. a wire brush; 8. a contact sizing device; 81. a long connecting rod; 82. a movable contact; 83. a sizing device support; 84. a stationary contact; 85. A protective cover; 87. and a return spring.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, an embodiment of the present invention provides a method for directly rolling a steel bar without heating, including: sequentially carrying out the working procedures of blast furnace molten iron smelting, molten iron desulfurization pretreatment, converter molten steel smelting, billet continuous casting, hot continuous rolling and fixed-length shearing; wherein, the blank heating procedure between the continuous casting of the square billet and the hot continuous rolling is removed; in the billet continuous casting process, controlling the difference value between the head temperature and the tail temperature of a casting blank to be 20-40 ℃; in the hot continuous rolling process, the difference between the head temperature and the tail temperature of the rolled piece is controlled to be 20-30 ℃.
In the heating-free direct rolling process, as the casting blank is not required to be reheated by a heating furnace, the tail temperature of the casting blank is obviously higher than the head temperature, and the closer to the tail temperature, the higher the tail temperature of a rolled piece is, the corresponding tail temperature in the subsequent process is also obviously higher than the head temperature, so that the head and tail strength of a finished product piece is inconsistent, and further the quality problem is generated. Analysis and actual measurement prove that the difference between the head temperature and the tail temperature of the casting blank is controlled to be 20-40 ℃, and the difference between the head temperature and the tail temperature of the rolled piece is controlled to be 20-30 ℃, so that the quality of the final steel bar finished product can be effectively ensured, and the strength of the head and the tail of the steel bar finished product tends to be consistent.
The rolling method eliminates a heating furnace; the casting blank is directly sent into the rolling mill through the blank feeding roller way, and the casting blank is not required to be sent into the heating furnace through the blank feeding roller way. In addition, in order to reduce casting blank temperature drop, the whole process from the continuous casting machine to the inlet of the rolling mill is covered by a fully-closed multi-layer heat preservation cover. The outer layer of the heat preservation cover is a steel shell, the middle layer is high-temperature resistant heat preservation cotton, and the inner layer is high-temperature resistant reflecting material, so that heat loss is reduced to the greatest extent
Further, before the blast furnace molten iron smelting process, the method further comprises:
the chemical components and weight percentages of the steel bars are determined as follows: c:0.20 to 0.25Wt percent, si:0.40 to 0.55Wt percent, mn:1.10 to 1.25Wt percent, P: less than or equal to 0.045wt%, S: less than or equal to 0.045wt%, nb: less than or equal to 0.004Wt percent, ti: less than or equal to 0.007wt%, alt: less than or equal to 0.006wt%, V:0.02 to 0.03Wt percent, N: 0.005-0.011 wt%.
In order to obtain better effects, the application carries out special component design:
1) And reducing the addition of alloying elements with low solubility, such as Nb, ti and Al, after austenitizing the steel at the direct rolling temperature. The alloy elements have high melting points of nitrides and carbides formed in the steel at the direct rolling temperature, are difficult to dissolve, and can inhibit recrystallization and grain growth after recrystallization in the rolling process, so that the fine grain strengthening effect is obvious in the direct rolling state. If the elements are added, the temperature change of the rolled piece has larger influence on the performance of the steel, the temperature difference between the head and the tail of the rolled steel of the casting blank is increased, and the quality stability of the product is influenced.
2) Adding proper amount of V element. At the direct rolling temperature, the nitrides and carbides of the vanadium element are almost completely dissolved in the austenite region, and mainly play a role in precipitation strengthening in the steel.
3) And controlling the N element. N can strengthen the strengthening effect of V, reduce the cost and can be added in the form of silicon nitride iron. As in table 1.
4) Controlling Si and Mn content. Si and Mn play a solid solution strengthening role, and the strengthening effect is little influenced by the temperature of a casting blank. Si contributes more to tensile strength, mn contributes more to tensile strength and yield strength, and since the rolling temperature is low and the fine grain strengthening effect is stronger in the direct rolling state, a certain amount of Si is required to ensure that the yield ratio is acceptable
Further, the steel bars comprise the following chemical components in percentage by weight: c:0.23wt%, si:0.50wt%, mn:1.19wt%, P:0.030wt%, S:0.026wt%, nb:0.002Wt%, ti:0.002Wt%, alt:0.0019wt%, V:0.026wt%, N:0.0075Wt%.
Experiments prove that better implementation effect can be obtained after the chemical components of the material are selected from the values.
Further, the difference between the temperature of the head and the temperature of the tail of the casting blank is controlled to be 20-40 ℃, and the method specifically comprises the following steps: setting a casting blank fixed-length shearing procedure in the square billet continuous casting procedure; the casting blank fixed-length shearing process is completed by adopting hydraulic shears; the casting blank fixed-length shearing process specifically comprises the following steps: a contact sizing device is arranged on the blank feeding roller way at a preset distance from the hydraulic shears; when the head of the casting blank contacts the contact type sizing device, the contact type sizing device outputs a shearing action signal to a control system; a control system sends out an action command to the hydraulic shear; and cutting off the casting blank by the hydraulic shears according to the action instruction.
The casting blank sizing is controlled in two ways, namely, the contact mechanical device control sizing and the infrared imaging control sizing. Before the step blank is formed, the step blank is formed by adopting a stopper rod flow control and infrared imaging mode, then all heat preservation covers are covered, the drawing speed of each flow is controlled to be equal, and the contact type mechanical device (namely a contact type sizing device) is switched to control the cutting according to the sizing. The step knockout mode is used, so that the casting blank can enter the high-speed blank feeding roller way as soon as being sheared, and enter the rolling mill at the fastest speed, and the temperature drop under the waiting time is reduced.
The continuous casting machine uses the hydraulic shear to shear the casting blank, the shearing speed of the hydraulic shear is high, and the waiting time and the temperature drop of the casting blank can be reduced. The contact type sizing device 8 is structured as shown in fig. 6, and a mechanical contact type sizing device 8 is provided at a casting block sizing position (for example, at a position 10m or 11m from a hydraulic shear). The contact type sizing device 8 is provided with a long connecting rod 81 which is horizontally arranged, the middle part of the long connecting rod 81 is hinged with a sizing device support 83, the long connecting rod can rotate by taking a hinging point as a circle center, one end of the long connecting rod 81 stretches into the inner side of the blank feeding roller way 3 through an opening on the blank feeding roller way side plate 31 and is positioned on the running track of a casting blank 1, the other end of the long connecting rod is provided with a movable contact 82, a fixed contact 84 is fixedly arranged above the movable contact 82, and the fixed contact 84 is electrically connected with a signal receiving end of an external control system 6 through a wire. When the casting blank 1 moves to the position of the contact type sizing device 8 on the blank feeding roller way 3, one end of the long connecting rod 81 extending to the inner side of the blank feeding roller way 3 is pressed down, and the other end is reversely lifted (meanwhile, the reset spring 87 is lengthened), so that the movable contact 82 contacts the fixed contact 84, an electric signal is given to the control system 6 (a computer or a PLC (programmable logic controller) and the like), the control system 6 immediately gives a shearing signal to the hydraulic shear, and the hydraulic shear cuts off the casting blank 1; the casting blank 1 is cut off and then is conveyed away by the blank conveying roller way 3, the contact type sizing device 8 is reset (namely, the long connecting rod 81 is restored to the initial horizontal state) under the action of the tension of the reset spring 87, when the next casting blank 1 passes through again, the long connecting rod 81 of the contact type sizing device 8 is pressed down again, and the control system 6 gives a casting blank cutting signal for 1 time again. And repeating the steps to realize continuous casting blank shearing operation. In the device, in order to avoid scratching the casting blank 1, a plurality of cylindrical guide wheels can be arranged at one end part of the long connecting rod 81 extending to the inner side of the blank feeding roller way 3, and the guide wheels can rotate along with the movement of the casting blank 1 when contacting the casting blank 1. Meanwhile, in order to avoid foreign matter falling into and affecting use, a protective cover 85 can be arranged on the outer side of the device, and when adjustment or maintenance is needed, the protective cover 85 can be lifted from the upper side to be removed. In order to ensure reliable contact and avoid contact failure, the stationary contact 84 may be made of a long sheet-like elastic metal material.
In order to reduce heat loss as much as possible, a heat preservation cover between a withdrawal and straightening machine of the continuous casting machine and the hydraulic shear is not provided with holes, and a small hole with the diameter of 10mm is formed in the position of the heat preservation cover at the upper part of the hydraulic shear, so that the position of a casting blank can be conveniently observed.
Further, the difference between the temperature of the head and the temperature of the tail of the casting blank is controlled to be 20 ℃ to 40 ℃, and the method further comprises the following steps: setting an oxide scale removing process, a casting blank measuring process and a casting blank cooling control process after a fixed-length shearing process in the square billet continuous casting process; in the step of removing the oxide skin, the oxide skin on the side surface of the casting blank is removed through a steel wire brush; in the casting blank measuring procedure, the temperature of the side surface of the casting blank from which the oxide skin is removed is recorded and measured according to a preset time interval by a pyrometer, and a casting blank temperature curve is generated according to the measuring result, wherein the casting blank temperature curve is used for reflecting the temperature difference of different positions from the head part to the tail part of the casting blank; and finishing the casting blank cooling control procedure according to the casting blank temperature curve.
In order to control the temperature difference of the head and the tail of a casting blank, the casting blank cooling control spray head with special design is adopted, and the temperature of the part with higher temperature at the middle and rear ends of the casting blank is cooled down so as to be consistent with the temperature of the head. In order to reasonably control the temperature change, the water yield of the spray heads needs to be quantified and reasonably controlled, therefore, before the casting blank cooling control spray heads are adopted for cooling, the temperature of the surface of the casting blank is measured firstly to obtain the actual temperature of each recorded point, a temperature curve for reflecting the temperature change trend of different positions of the casting blank is drawn according to the actual temperature of each recorded point, and then the temperature curve is input into a control system, so that the control system can treat each point on the casting blank differently according to the temperature curve, the higher the temperature is, the larger the water yield of the corresponding casting blank cooling control spray heads is, the largest the cooling amplitude is, and the lower the water yield is. By the method, the difference between the temperature of the head part and the temperature of the tail part of the casting blank can be controlled between 20 ℃ and 40 ℃.
In order to avoid the influence of scale on the accuracy of the subsequent temperature measurement, the scale on the surface of the casting blank should be removed before the temperature is measured. The iron scale removing device is a cylindrical steel wire brush 7 driven by a motor to rotate, and the rotating direction of the steel wire brush is opposite to the moving direction of the casting blank 1; the cylindrical steel wire brush 7 is perpendicular to the ground and is arranged on the side surface of the billet conveying roller way 3 in front of the rolling mill, and when the casting billet 1 passes through, the motor drives the steel wire brush 7 to rotate so as to remove iron scales on the surface of the casting billet 1.
After the iron scale removing device, a plurality of temperature measuring points are further arranged along the direction of the blank feeding roller way 3, a pyrometer 5 is arranged at each casting blank temperature measuring point to measure the casting blank temperature, the casting blank temperature measuring points and a cylindrical steel wire brush 7 are positioned on the same horizontal line, the pyrometer 5 measures the casting blank 1 temperature after the iron scale is removed, measured values are recorded at preset time intervals (for example, 1 number is recorded every 0.1S), and after the measured values are transmitted into a control system 6 (for example, a computer and the like), trend lines can be drawn according to the measured value data, and represent the temperature condition from the head part to the tail part of the casting blank 1.
As shown in fig. 2, in order to meet the special requirements of the procedures of removing oxide scales, measuring temperature of casting blanks and controlling cooling of casting blanks, a section of special heat-preserving cover 2 for measuring temperature and controlling cooling is included in the heat-preserving cover (the heat-preserving layer structure of the heat-preserving cover is not different from the heat-preserving cover or the prior common heat-preserving cover, but is called the special heat-preserving cover because the equipment such as an oxide scale removing device, a temperature measuring point, a temperature adjusting device and the like is arranged in the heat-preserving cover), and the special heat-preserving cover 2 is positioned in front of a rolling mill. Along the conveying direction of the casting blank 1, the special heat-preserving cover 2 comprises three working procedures of equipment, namely an iron scale removing device, a casting blank temperature measuring point and a casting blank temperature adjusting device, wherein the iron scale removing device is positioned in the special heat-preserving cover 2.
Further, the step of completing the cooling control process of the casting blank according to the casting blank temperature curve specifically comprises the following steps: determining a starting position which is 20 ℃ higher than the temperature of the head of the casting blank on the casting blank according to the casting blank temperature curve; spraying water to the part behind the initial position on the casting blank through casting blank cooling control spray heads respectively arranged at the upper left, lower right and upper right of the outer side of the casting blank; and adjusting the water spraying intensity of each spray head in real time according to the casting blank temperature curve and the moving speed of the casting blank.
A temperature adjusting device is also arranged in the special heat preservation cover 2 for completing the cooling control process. The length of the temperature adjusting device is equivalent to that of the casting blank 1, and as shown in fig. 3, the temperature adjusting device mainly comprises a plurality of casting blank spray heads 4, and the casting blank spray heads 4 are arranged at four corner positions of a special heat preservation cover 2 outside a blank feeding roller way 3. Moreover, it should be ensured that 1 casting blank nozzle 4 is respectively arranged on 4 corners of the same section of the casting blank 1, namely 4 casting blank nozzles 4 are arranged in total in the same section, namely, the upper left, the upper right, the lower left and the lower right, and the casting blank nozzle 4 is not arranged under the casting blank 1, so that the casting blank nozzle 4 is prevented from being blocked due to falling of iron scales on the casting blank 1 and further cannot be used. In the length direction of the special heat preservation cover 2, casting blank spray heads 4 are uniformly arranged, namely 4 rows of casting blank spray heads are formed, and the spacing of the casting blank spray heads on the same row takes the principle that sprayed water can completely cover the surface of the casting blank 1 as a configuration principle. Since gaps are formed between the lower rollers and the side surfaces of the billet feeding roller table 3, the billet spray heads 4 positioned at the left lower side and the right lower side can spray cooling water to the side surfaces and the lower sides of the billets 1.
In addition, the spray hole 41 of the casting blank spray head 4 should not adopt a common round hole design, but the spray hole 41 is designed to be a hollow rectangle (as shown in fig. 5), so that the protection range of sprayed water can be formed into a rectangular spray coverage area 42 (also called an annular spray coverage area with rectangular periphery, and the protection range of common round hole water outlet is circular or ring-shaped) as shown in fig. 4. In this way, the casting blank 1 is square blank, and the casting blank spray heads 4 are arranged at four corner points on the inner side of the special heat preservation cover 2, so that the casting blank spray heads 4 are positioned on diagonal lines of square sections of the casting blank 1; because the corner 11 of the casting blank 1 is two-dimensional heat transfer and the temperature drop speed is high, the water quantity at the middle part of the water spray coverage area 42 sprayed by the casting blank spray head 4 is small, the water quantity at the two sides is large, the overlarge temperature drop of the corner 11 of the casting blank 1 can be avoided, and the overall temperature uniformity of the casting blank 1 is maintained.
When the head of the casting blank 1 enters a rolling mill, water spraying is started to control the surface temperature, the temperature of the head area of the casting blank 1 is lower, and water is not sprayed; based on the surface temperature trend curve of the casting blank 1, the water quantity of the casting blank spray head 4 is controlled by a computer (a control system 6), water spray cooling is started when the temperature of the casting blank 1 is raised by 20 ℃ from the head of the casting blank 1, the more the temperature is raised, the higher the water spray intensity is, and the water outlet area moves along with the movement of the casting blank 1.
Further, the difference between the head temperature and the tail temperature of the rolled piece is controlled to be 20 ℃ to 30 ℃, and the method specifically comprises the following steps: the hot continuous rolling process is sequentially provided with rough rolling, rough rolling controlled cooling, middle rolling controlled cooling, finish rolling and finish rolling controlled cooling processes; the rough rolling process comprises a rough rolling process step, a rough rolling process step and a rough rolling process step, wherein temperature measurement is carried out in the rough rolling process step, and a first temperature curve is generated according to measurement results; the rough rolling and cooling control process specifically comprises the following steps: a water spray head is arranged on the outer side of the rolled piece; selecting a water spraying starting position on a rolled piece; spraying water to a part after the water spraying starting position on the rolled piece through the water spray nozzle; and adjusting the water spraying intensity of each water spray head in real time according to the first temperature curve.
In order to reasonably control the temperature change, the water yield of each cooling control device needs to be quantified and reasonably controlled, so that before cooling control, the temperature of the surface of a rolled piece is measured, the actual temperature of each recorded point is obtained, a temperature curve of the temperature change trend of different positions of the rolled piece is drawn according to the actual temperature of each recorded point, and then the temperature curve is input into a control system, so that the control system discriminates each point on the rolled piece according to the temperature curve, the higher the temperature is, the greater the corresponding cooling control intensity is, the largest the cooling amplitude is, and the lower the temperature is, the lower the cooling control intensity is.
For this purpose, a plurality of temperature measuring points can be arranged along the direction of the blank feeding roller table, and are distributed at corresponding positions in the processes of rough rolling, intermediate rolling, pre-finish rolling, finish rolling and the like. Each temperature measuring point is provided with a pyrometer for temperature measurement, measured values are recorded at preset time intervals (for example, 1 number is recorded every 0.1S), and after the measured values are transmitted into a control system (for example, a computer and the like), a temperature curve representing the current head-tail temperature difference condition of the rolled piece can be drawn according to a plurality of measured value data.
In the rough rolling temperature control procedure, a special water spray head is adopted as a cooling control device, a plurality of water spray heads are arranged at proper distances outside a rolled piece, the water spray heads are arranged at four corner positions around the outer side of a blank feeding roller way, and a bracket can be arranged for fixing the water spray heads. In addition, it should be ensured that 1 water spray head is respectively arranged at 4 corners of the same cross section of the rolled piece 1, that is, 4 water spray heads are arranged at the upper left, the upper right, the lower left and the lower right in the same cross section, and the water spray heads 4 are not arranged under the casting blank 1 so as to avoid blockage caused by impurities and the like falling on the rolled piece 1. In the length direction of the blank feeding roller way, the water spray heads are uniformly arranged, namely 4 rows of spray heads are formed, and the intervals between the spray heads on the same row take the principle that sprayed water can completely cover the surface of the rolled piece 1 as a configuration principle. In order to control the temperature difference between 20 ℃ and 30 ℃, before water spraying and cooling, a position which is 20 ℃ higher than the temperature of the head of the rolled piece is found on the rolled piece according to a temperature curve generated in advance to serve as a water spraying starting position, and the part after the water spraying starting position is cooled.
Further, the controlling the difference between the head temperature and the tail temperature of the rolled piece to be 20-30 ℃ further comprises: temperature measurement is carried out in the middle rolling procedure, and a second temperature curve is generated according to the measurement result; the middle rolling cooling control procedure adopts a water penetrating device to adjust the temperature of a rolled piece, and adjusts the cooling control intensity of the middle rolling cooling control procedure in real time according to the second temperature curve; temperature measurement is carried out in the finish rolling process, and a third temperature curve is generated according to the measurement result; and the finish rolling cooling control procedure adopts a multi-stage cooling controller to adjust the temperature of a rolled piece, and adjusts the cooling control intensity of the finish rolling cooling control procedure in real time according to the third temperature curve.
In the rest of the cooling control process, although other cooling control devices except the water spray head are used, the cooling control amount is adjusted according to the corresponding temperature curve. Temperature measuring points are respectively arranged in the middle rolling stand and the finish rolling stand, so that respective corresponding temperature curves are generated according to temperature measuring results in the middle rolling process and the finish rolling process, and the respective corresponding temperature curves are used for controlling and adjusting in the middle rolling and finish rolling and cooling control processes.
Further, after the finish rolling and cooling control process, the method further comprises: temperature measurement after finish rolling and cold control process after finish rolling; the temperature measurement is carried out in the temperature measurement process after finish rolling, and a fourth temperature curve is generated according to the measurement result; and the temperature of the rolled piece is adjusted by adopting a multi-stage cold controller in the finish rolling post-cold control process, and the cold control intensity of the finish rolling post-cold control process is adjusted in real time according to the fourth temperature curve.
In some rolling stock production lines, besides rough rolling, intermediate rolling and finish rolling, the cold control treatment (namely, cold control after finish rolling) is required to be performed again after the finish rolling cold control process, at this time, temperature measurement is also required to be performed and a temperature curve is generated, and then the finish rolling cold control process is performed according to the temperature curve.
Further, the method further comprises a pre-finish rolling and pre-finish rolling cooling control process before the finish rolling process; the temperature measurement is carried out in the pre-finish rolling procedure, and a fifth temperature curve is generated according to the measurement result; and the pre-finish rolling cooling control procedure adopts a multi-stage nozzle to adjust the temperature of a rolled piece, and adjusts the cooling control intensity of the pre-finish rolling cooling control procedure in real time according to the fifth temperature curve.
In some rolling production lines, pre-finish rolling is needed between intermediate rolling and finish rolling, and temperature measurement should be performed during the pre-finish rolling process to generate a corresponding temperature curve, and then a pre-finish rolling cooling control process is performed according to the temperature curve.
The control method of the head-tail temperature difference of the rolled piece in the application is specifically described below:
1. the design of the rolling line: the rolling line is provided with a multi-level cold control device in the rolling process.
Ordinary bar production line: the temperature measurement device comprises 6 roughing mills, rough rolling cold control devices, 6 middle rolling mills, 4 finishing mills, finish rolling cold control devices, a restoring section, a temperature measuring device after finish rolling, 2 finishing mills, a cold control device after finish rolling, a restoring section and a cooling bed (temperature measurement is respectively carried out after the 4 th frame of the roughing mill, the middle rolling mill and the finishing mill), the restoring time can be provided for rolled pieces before temperature measurement, the surface temperature is uniform, and the phenomenon that the surface temperature measurement precision is affected due to uneven surface temperature and supercooling of the rolled pieces caused by the cold control devices is avoided.
High-speed bar production line: the temperature measurement device comprises 6 roughing mills, rough rolling cold control devices, 6 middle rolling mills, 6 pre-finishing mills, pre-finishing rolling cold control devices, 4 finishing mills, finish rolling cold control devices, a restoring section, a temperature measurement device after finish rolling, 2 finishing mills, a cold control device after finish rolling, a restoring cold bed (temperature measurement is respectively carried out after the 4 th stand of the rough rolling, the middle rolling, the pre-finishing rolling and the finishing mill, so that restoring time can be provided for rolled pieces before temperature measurement, the surface temperature is uniform, and uneven surface temperature and supercooling of the rolled pieces caused by the cold control devices are avoided).
High-speed wire rod production line: the temperature measuring device comprises a 6-frame roughing mill, a rough rolling cold control device, a 6-frame middle rolling mill, a 6-frame pre-finishing mill, a pre-finishing mill cold control device, a recovery section, an 8-frame finishing mill, a finish rolling cold control device, a recovery section, a post-finish rolling temperature measuring device, a 2-frame diameter shearing unit and a post-finish rolling cold control device (for measuring temperature after a 4 th frame of rough rolling, middle rolling and pre-finish rolling and an 8 th frame of the finishing mill respectively), and can provide recovery time and uniform surface temperature for rolled pieces before temperature measurement and avoid uneven surface temperature and supercooling of the rolled pieces caused by the cold control device).
2. According to the temperature obtained by the rolled piece at each measuring point, drawing a temperature trend line at each measuring point, and adjusting the temperature of the rolled piece according to the temperature trend line in a cooling control process after each measuring point of the rolling line, so as to control the temperature difference between the head and the tail of the rolled piece. Based on the trend line of the surface temperature of the rolled piece, the water spray cooling is started from the part of the head of the rolled piece, which is raised by 20 ℃ compared with the head, and the water spray intensity is higher as the temperature is raised more.
3. Different cold control devices are adopted at different positions: the rough rolling cooling control process adopts a water nozzle, the medium rolling cooling control process adopts a water penetrating device, the pre-finish rolling cooling control process adopts a multi-stage nozzle, the finish rolling cooling control process and the finish rolling post-cooling control process adopt a multi-stage cooling control device.
Wherein, rough rolling accuse cold adopts the water shower nozzle: because the rolled piece at the rough rolling outlet is large, and the head part can have bending and other problems, a cooling device (namely a cooling control device) is arranged behind the No. 1 flying shear, and the cooling device at the position consists of a plurality of groups of water spray heads. And 1 water spray nozzle is respectively arranged on 4 corners of the same section of the rolled piece, and 4 water spray nozzles are arranged in the same section, so that the spray nozzles positioned right below can be prevented from being blocked due to falling of cast blank iron scales, and the use is influenced. The water outlet shape of the water spray heads is rectangular, and the coverage area of the water spray heads is based on that 4 spray heads completely cover the surface of the rolled piece.
The middle rolling and cooling control is a water penetrating device: because the size of the rolled piece at the middle rolling outlet is larger, the head part can have bending and other problems, a cooling device (a cooling control device) is arranged behind the No. 2 flying shears, and the cooling device is cooled by using a water penetrating device commonly used for bar rolling lines.
The pre-finish rolling, the finishing mill and the post-finish rolling cooling control are all multi-stage coolers (grading cooling control devices), and each position is composed of a plurality of small cooling control devices capable of controlling water quantity independently.
The method for directly rolling the steel bar without heating of the present application will be described with a specific example as follows:
in one embodiment for producing HRB400E rebar, the chemical composition of the materials is shown in the following table:
HRB400E component (wt%)
Table 1.Hrb400e material composition table
The steelmaking process of this example is:
the process route is as follows: smelting blast furnace molten iron, desulfurizing molten iron pretreatment, smelting converter molten steel, continuous casting of square billets, hot continuous rolling, fixed-length shearing, inspection, packaging and warehousing; wherein, the technological characteristics of each stage are:
smelting converter molten steel: the molten iron S fed into the furnace is 0.040wt%; alloy with higher Nb, ti and Al contents is not added after the furnace.
The slag elution S process is adopted after the converter: slag forming materials such as lime, synthetic slag and the like are respectively added into the steel ladle before and during tapping, reasonable slag components and fluidity are controlled, and a deoxidization process, a temperature control process and a chlorine blowing process are standardized, so that the aim of slag washing and desulfurization is fulfilled. (1) ladle top slag alkalinity (CaO/SiO 2) 2.8. (2) And additionally adding deoxidizing materials in the tapping process to carry out reinforced deoxidization on molten steel and top slag, and adding the deoxidizing materials to the ladle slag surface after tapping, wherein the ladle top slag (FeO) is 1.7% after tapping. And (3) the tapping temperature is increased by 15 ℃ compared with the conventional low S heat. (4) The stirring intensity in the tapping process and the desulfurization process is improved, and the strong argon blowing time after tapping is 6 minutes.
Continuous casting of square billets: the ladle slag discharge detection control is adopted, the pouring temperature of the tundish is 1530 ℃, the tundish uses a common covering agent, the common square billet casting powder is used, and the single-flow drawing speed of the casting blank is 3.6m/min. The casting blank is sheared by hydraulic shear, and the casting blank is ejected in a step ejection mode, wherein the temperature of the casting blank at the shearing position is 1000-1100 ℃, such as 1020 ℃, 1050 ℃ and 1080 ℃. The specific water content of the casting stream was 1.1L/min using an all-water cooled nozzle.
As shown in fig. 2, this rolling method eliminates the heating furnace; the casting blank is directly sent into the rolling mill through the blank feeding roller way 3, and the casting blank is not required to be sent into the heating furnace through the blank feeding roller way 3. Hot continuous rolling of bars: the blank is sent into a rolling mill from a direct-feeding roller way, a high-speed motor is used for feeding blanks, and the length of the blank feeding roller way 3 is within 200m, for example, 180 meters or 200 meters. The time from cutting of the slab to entry into the mill was 60 seconds.
The section of the casting blank is 165mm multiplied by 165mm, the length of the casting blank is 11m, the temperature curve generated after mapping shows that the temperature of the 5m part of the casting blank is 20 ℃ higher than the temperature of the head part, the temperature of the 10m part of the casting blank is 55 ℃ higher than the temperature of the head part, water spray cooling is started from the 5m part of the casting blank, the more the temperature is increased, the higher the water spray intensity is, and finally the temperature difference of the head part and the tail part of the casting blank is controlled to be 28 ℃.
Before entering a rolling mill, the temperature of the head of the casting blank is 890-910 ℃, the temperature of the tail of the casting blank is 870-875 ℃, for example, the temperature of the head of the casting blank is 900 ℃, and the temperature of the tail of the casting blank is 873 ℃.
The production line is arranged according to the common bar production line, namely, 6 roughing mills, rough rolling cold control devices, 6 middle rolling mills, middle rolling cold control devices, 4 finishing mills, finish rolling cold control devices, a restoring section, a temperature measuring device after finish rolling, 2 finishing mills, a temperature measuring device after finish rolling, a restoring section and a cooling bed (temperature measuring is respectively carried out after the 4 th stand of rough rolling, middle rolling and finishing mills, and the temperature measuring device can provide restoring time and uniform surface temperature for rolled pieces before temperature measuring). The steel bar is 28mm in size, the length of the finished product of the rolled piece is 486m after being put on a cooling bed, and finally the temperature difference between the head and the tail of the rolled piece is controlled to be 25 ℃.
The final results are shown in the following table:
TABLE 2 head-to-tail temperature and head-to-tail performance summary
In the instant hot continuous rolling, the temperature of the head of the rolled piece is controlled to be 890-910 ℃, the temperature of the tail of the rolled piece is controlled to be 860-890 ℃, the difference of the yield strength of the head and the tail is less than or equal to 30Mpa, and the difference of elongation after breaking is less than or equal to 2%, for example:
the temperature of the head of the first rolled piece is 900 ℃, the yield strength of the head of the rolled piece is 440Mpa, and the elongation after breaking is 21%; the tail temperature is 880 ℃, the yield strength of the tail of the rolled piece is 455Mpa, and the elongation after breaking is 22%;
the temperature of the head of the second rolled piece is 905 ℃, the yield strength of the head of the rolled piece is 430Mpa, and the elongation after breaking is 20%; the tail temperature is 880 ℃, the yield strength of the tail of the rolled piece is 450Mpa, and the elongation after breaking is 21%;
the temperature of the head of the third rolled piece is 892 ℃, the yield strength of the head of the rolled piece is 425Mpa, and the elongation after breaking is 23%; the tail temperature is 863 ℃, the yield strength of the tail of the rolled piece is 455Mpa, and the elongation after breaking is 22%; the method comprises the steps of carrying out a first treatment on the surface of the
The temperature of the head of the fourth rolled piece is 910 ℃, the yield strength of the head of the rolled piece is 435Mpa, and the elongation after breaking is 22%; tail temperatureThe degree is 890 ℃, the yield strength of the tail part of the rolled piece is 460Mpa, and the elongation after breaking is 20%. Compared with the traditional cold billet reheating, the ton of steel can save 140m of gas 3 The loss of cast blank iron scale is reduced, and the steel rolling metal yield is improved by 0.5-1.0%.
In the foregoing detailed description, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the subject matter require more features than are expressly recited in each claim. Rather, as the following claims reflect, invention lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate preferred embodiment of this invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. As will be apparent to those skilled in the art; various modifications to these embodiments will be readily apparent, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (7)
1. A method for direct rolling of steel bars without heating, comprising:
sequentially carrying out the working procedures of blast furnace molten iron smelting, molten iron desulfurization pretreatment, converter molten steel smelting, billet continuous casting, hot continuous rolling and fixed-length shearing;
wherein, the blank heating procedure between the continuous casting of the square billet and the hot continuous rolling is removed;
in the billet continuous casting process, controlling the difference value between the head temperature and the tail temperature of a casting blank to be 20-40 ℃;
in the hot continuous rolling process, the difference between the head temperature and the tail temperature of a rolled piece is controlled to be 20-30 ℃;
the difference between the head temperature and the tail temperature of the casting blank is controlled to be 20-40 ℃, and the method further comprises the following steps:
setting an oxide scale removal process, a measurement process and a casting blank cooling control process after the fixed-length shearing process; wherein,
in the step of removing the oxide skin, the oxide skin on the side surface of the casting blank is removed through a steel wire brush;
in the measuring procedure, measuring the temperature of the side surface of the casting blank from which the oxide skin is removed at preset time intervals through a pyrometer, and generating a casting blank temperature curve according to the measuring result, wherein the casting blank temperature curve is used for reflecting the temperature difference of different positions from the head part to the tail part of the casting blank;
completing the casting blank cooling control procedure according to the casting blank temperature curve;
the casting blank cooling control process is completed according to the casting blank temperature curve, and specifically comprises the following steps:
determining a starting position which is 20 ℃ higher than the temperature of the head of the casting blank on the casting blank according to the casting blank temperature curve;
spraying water to the part behind the initial position on the casting blank through casting blank cooling control spray heads respectively arranged at the upper left, lower right and upper right of the outer side of the casting blank;
the water spraying intensity of each casting blank cooling control spray head is adjusted in real time according to the casting blank temperature curve and the moving speed of the casting blank;
the shape of the spray hole on the casting blank cooling control spray nozzle is a hollow rectangle.
2. The method for direct rolling of steel bars without heating according to claim 1, further comprising, before the blast furnace hot metal smelting process:
the chemical components and weight percentages of the steel bars are determined as follows: c:0.20 to 0.25Wt percent, si:0.40 to 0.55Wt percent, mn:1.10 to 1.25Wt percent, P: less than or equal to 0.045wt%, S: less than or equal to 0.045wt%, nb: less than or equal to 0.004Wt percent, ti: less than or equal to 0.007wt%, alt: less than or equal to 0.006wt%, V:0.02 to 0.03Wt percent, N: 0.005-0.011 wt%.
3. The method for directly rolling the steel bar without heating according to claim 1, wherein the difference between the temperature of the head and the temperature of the tail of the casting blank is controlled to be 20-40 ℃, and the method specifically comprises the following steps:
setting a casting blank fixed-length shearing procedure in the square billet continuous casting procedure;
the casting blank fixed-length shearing process is completed by adopting hydraulic shears; the casting blank fixed-length shearing process specifically comprises the following steps:
a contact sizing device is arranged on the blank feeding roller way at a preset distance from the hydraulic shears;
when the head of the casting blank contacts the contact type sizing device, the contact type sizing device outputs a shearing action signal to a control system;
a control system sends out an action command to the hydraulic shear;
and cutting off the casting blank by the hydraulic shears according to the action instruction.
4. The method for direct rolling steel bar without heating according to claim 1, wherein the difference between the head temperature and the tail temperature of the rolled piece is controlled to be 20 ℃ to 30 ℃, and the method specifically comprises the following steps:
the hot continuous rolling process is sequentially provided with rough rolling, rough rolling controlled cooling, middle rolling controlled cooling, finish rolling and finish rolling controlled cooling processes;
the rough rolling process comprises a rough rolling process step, a rough rolling process step and a rough rolling process step, wherein temperature measurement is carried out in the rough rolling process step, and a first temperature curve is generated according to measurement results;
the rough rolling and cooling control process specifically comprises the following steps:
a water spray head is arranged on the outer side of the rolled piece;
selecting a water spraying starting position on a rolled piece;
spraying water to a part after the water spraying starting position on the rolled piece through the water spray nozzle;
and adjusting the water spraying intensity of each water spray head in real time according to the first temperature curve.
5. The method of direct rolling steel bar without heating according to claim 4, wherein the difference between the head temperature and the tail temperature of the rolled piece is controlled to be 20 ℃ to 30 ℃, further comprising:
temperature measurement is carried out in the middle rolling procedure, and a second temperature curve is generated according to the measurement result;
the middle rolling cooling control procedure adopts a water penetrating device to adjust the temperature of a rolled piece, and adjusts the cooling control intensity of the middle rolling cooling control procedure in real time according to the second temperature curve;
temperature measurement is carried out in the finish rolling process, and a third temperature curve is generated according to the measurement result;
and the finish rolling cooling control procedure adopts a multi-stage cooling controller to adjust the temperature of a rolled piece, and adjusts the cooling control intensity of the finish rolling cooling control procedure in real time according to the third temperature curve.
6. The method of direct rolling reinforcement bar without heating according to claim 5, further comprising, after the finish rolling and cooling control process:
temperature measurement after finish rolling and cold control process after finish rolling;
the temperature measurement is carried out in the temperature measurement process after finish rolling, and a fourth temperature curve is generated according to the measurement result;
and the temperature of the rolled piece is adjusted by adopting a multi-stage cold controller in the finish rolling post-cold control process, and the cold control intensity of the finish rolling post-cold control process is adjusted in real time according to the fourth temperature curve.
7. The method according to claim 6, further comprising a pre-finish rolling and pre-finish rolling cooling control step before the finish rolling step;
the temperature measurement is carried out in the pre-finish rolling procedure, and a fifth temperature curve is generated according to the measurement result;
and the pre-finish rolling cooling control procedure adopts a multi-stage nozzle to adjust the temperature of a rolled piece, and adjusts the cooling control intensity of the pre-finish rolling cooling control procedure in real time according to the fifth temperature curve.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210471382.0A CN114799095B (en) | 2022-04-28 | 2022-04-28 | Reinforcement bar heating-free direct rolling method and reinforcement bar rolled by heating-free direct rolling method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210471382.0A CN114799095B (en) | 2022-04-28 | 2022-04-28 | Reinforcement bar heating-free direct rolling method and reinforcement bar rolled by heating-free direct rolling method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114799095A CN114799095A (en) | 2022-07-29 |
| CN114799095B true CN114799095B (en) | 2023-12-29 |
Family
ID=82511833
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210471382.0A Active CN114799095B (en) | 2022-04-28 | 2022-04-28 | Reinforcement bar heating-free direct rolling method and reinforcement bar rolled by heating-free direct rolling method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114799095B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116790979A (en) * | 2023-06-14 | 2023-09-22 | 重庆钢铁股份有限公司 | HRB500E ribbed double high rod and production method thereof |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101418363A (en) * | 2008-11-13 | 2009-04-29 | 湖南华菱涟源钢铁有限公司 | Method for producing low carbon and high ductility X60/X65pipeline steel |
| CN103451535A (en) * | 2013-09-18 | 2013-12-18 | 济钢集团有限公司 | Hot continuous rolling plate strip steel for 510MPa automotive frame and production technology thereof |
| CN109530646A (en) * | 2018-12-27 | 2019-03-29 | 钢铁研究总院 | For reducing the control method of head and tail temperature difference before direct rolling process continuous casting billet rolls |
| CN110711785A (en) * | 2019-10-10 | 2020-01-21 | 中冶南方连铸技术工程有限责任公司 | Method and system for controlling temperature of fixed-length casting blank before rolling |
| CN112391569A (en) * | 2020-10-14 | 2021-02-23 | 福建三宝钢铁有限公司 | Preparation method of 600MPa ultrahigh-strength anti-seismic steel bar |
| CN113403533A (en) * | 2021-05-28 | 2021-09-17 | 广西柳钢华创科技研发有限公司 | Method for producing HRB500E twisted steel bar by high-speed bar and HRB500E twisted steel bar produced by high-speed bar |
| CN113444968A (en) * | 2021-06-10 | 2021-09-28 | 广西柳钢华创科技研发有限公司 | HRB400E general speed hot rolling ribbed steel bar with tensile strength above 700Mpa and production method thereof |
| CN113441545A (en) * | 2021-06-10 | 2021-09-28 | 广西柳钢华创科技研发有限公司 | HRB500E normal speed hot rolled ribbed steel bar with yield ratio more than 1.28 and production method thereof |
| CN113528938A (en) * | 2021-06-10 | 2021-10-22 | 广西柳钢华创科技研发有限公司 | HRB600E normal speed hot rolled ribbed steel bar with yield ratio more than 1.26 and production method thereof |
-
2022
- 2022-04-28 CN CN202210471382.0A patent/CN114799095B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101418363A (en) * | 2008-11-13 | 2009-04-29 | 湖南华菱涟源钢铁有限公司 | Method for producing low carbon and high ductility X60/X65pipeline steel |
| CN103451535A (en) * | 2013-09-18 | 2013-12-18 | 济钢集团有限公司 | Hot continuous rolling plate strip steel for 510MPa automotive frame and production technology thereof |
| CN109530646A (en) * | 2018-12-27 | 2019-03-29 | 钢铁研究总院 | For reducing the control method of head and tail temperature difference before direct rolling process continuous casting billet rolls |
| CN110711785A (en) * | 2019-10-10 | 2020-01-21 | 中冶南方连铸技术工程有限责任公司 | Method and system for controlling temperature of fixed-length casting blank before rolling |
| CN112391569A (en) * | 2020-10-14 | 2021-02-23 | 福建三宝钢铁有限公司 | Preparation method of 600MPa ultrahigh-strength anti-seismic steel bar |
| CN113403533A (en) * | 2021-05-28 | 2021-09-17 | 广西柳钢华创科技研发有限公司 | Method for producing HRB500E twisted steel bar by high-speed bar and HRB500E twisted steel bar produced by high-speed bar |
| CN113444968A (en) * | 2021-06-10 | 2021-09-28 | 广西柳钢华创科技研发有限公司 | HRB400E general speed hot rolling ribbed steel bar with tensile strength above 700Mpa and production method thereof |
| CN113441545A (en) * | 2021-06-10 | 2021-09-28 | 广西柳钢华创科技研发有限公司 | HRB500E normal speed hot rolled ribbed steel bar with yield ratio more than 1.28 and production method thereof |
| CN113528938A (en) * | 2021-06-10 | 2021-10-22 | 广西柳钢华创科技研发有限公司 | HRB600E normal speed hot rolled ribbed steel bar with yield ratio more than 1.26 and production method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114799095A (en) | 2022-07-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR100960096B1 (en) | A continuous casting and rolling method for medium plate | |
| CN102796956B (en) | High-strength thin band steel for cold forming and manufacturing method thereof | |
| EP3859042A1 (en) | High-strength high-toughness non-quenched and tempered round steel and preparation method | |
| JP5130221B2 (en) | Manufacturing method of multi-phase structure hot strip | |
| CN102787280B (en) | Boron-containing weather-proof thin strip steel and manufacturing method thereof | |
| EP0177187A1 (en) | Method and apparatus for casting slabs | |
| CN103667895B (en) | A kind of manufacture method of cold formability high-strength thin strip steel | |
| CN100540708C (en) | High strength ship hull structure use steel and coiled sheet production method thereof | |
| CN1207113C (en) | Process and device for producing high-strength steel strip | |
| CN102796943B (en) | Thin strip steel for thin-wall oil drum and manufacturing method of thin strip steel | |
| CN103667878B (en) | A kind of Steel strip for thin-wall oil bucket and manufacture method thereof | |
| CN114799095B (en) | Reinforcement bar heating-free direct rolling method and reinforcement bar rolled by heating-free direct rolling method | |
| CN106269871B (en) | A kind of method for using increasing speed rolling technique productions thickness≤2.0mm low-intensity strips in CSP producing lines | |
| CN113441545B (en) | HRB500E plain-speed hot-rolled ribbed steel bar with strength-to-yield ratio of more than 1.28 and production method thereof | |
| CN112522566B (en) | Thin-specification patterned steel plate/strip and manufacturing method thereof | |
| CN101307411A (en) | Nb-containing high-carbon and high-duty steel based on sheet bar process and method for manufacturing same | |
| CN101333629B (en) | Method for producing medium-high-carbon high-strength steel based on sheet bar technology | |
| CN1978080A (en) | Band-steel producing process EPS | |
| AU663528B2 (en) | Method of manufacturing rolled material from oxygen-free copper | |
| CN113862552B (en) | Steel wire rod for welding and preparation method thereof | |
| CN103276286A (en) | Production method of X80 pipeline steel strip with thickness of 6-10 mm | |
| CN100404149C (en) | Sheet slab C-Mn excellent high-strength sheet-band steel production process | |
| CN112522575B (en) | Method for producing thin-specification pattern steel plate/strip through thin strip continuous casting | |
| CN111438188A (en) | Long material direct rolling casting blank heat preservation device, production line and method | |
| CN101351285B (en) | Method and apparatus for continuous casting |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |