A method for producing a hot-rolled carbon structural steel round bar

Abstract

The present application relates to the technical field of wire rod smelting, and specifically discloses a production method of carbon structural steel hot-rolled round disc rod, wherein the slab heating is performed at an opening temperature of 900-980 DEG C for carbon structural steel, and parameters of wire laying temperature, furnace discharge pinch roll speed, furnace discharge pinch roll lead rate and furnace discharge roller speed are set; the descaling before rolling is performed by setting high-pressure water descaling; the rolling is performed by adopting constant micro-tension rolling of the untwisted wire rod mill; the head and tail cutting after rolling is performed by setting the shearing parameters of 1# flying shear, 2# flying shear and 3# flying shear; the controlled cooling is performed by setting water cooling parameters, air cooling parameters and wire laying machine control parameters; and the compact bundling of the wire rod coil is performed because the wire rod produced by the untwisted wire rod mill is mostly heavy product, and the coil is collected at a controlled cooling temperature below 400 DEG C, the coil is relatively bulky, and the compact bundling must be performed; the present application ensures the consistency of the round rod diameter, avoids the broken round rod, improves the product quality, reduces the production cost, and improves the production efficiency.

Description

Technical Field

[0001] This invention relates to the field of wire rod smelting technology, specifically to a method for producing hot-rolled carbon structural steel round bars. Background Technology

[0002] Wire rod generally refers to hot-rolled round steel or equivalent shaped steel with a diameter of Ф5-16mm. Because it is delivered in coils, it is collectively called wire rod or wire mesh. Common wire rods are mostly round in cross-section, while shaped wire rods include elliptical, square, and threaded shapes, but these are produced in smaller quantities. Wire rods are classified according to their chemical composition into several categories: low-carbon wire rod (called soft wire), medium-high carbon wire rod (hard wire), low-alloy and alloy steel wire rod, stainless steel wire rod, and special steel wire rod (for bearings, tools, precision equipment, etc.). Carbon steel wire rod is the most widely produced, accounting for 80-90% of the total wire rod production.

[0003] The process of hot rolling carbon structural steel round bars is prone to diameter fluctuations or steel breakage due to unstable parameter settings, resulting in poor production quality, high production costs, and low production efficiency.

[0004] Therefore, it is necessary to design a production method for hot-rolled carbon structural steel round bars to solve the problem of poor production quality in the existing hot-rolled carbon structural steel round bar production process. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to provide a method for producing hot-rolled carbon structural steel round bars.

[0006] The technical solution adopted by this invention to solve its technical problem is: a method for producing hot-rolled carbon structural steel round bars, comprising the following steps:

[0007] S1. Steel billet heating: The initial rolling temperature of carbon structural steel is 900℃-980℃, and the parameters of wire drawing temperature, furnace exit pinch roll speed, furnace exit pinch roll lead rate, and furnace exit roller speed are set.

[0008] S2. Pre-rolling descaling: High-pressure water descaling is installed;

[0009] S3. Rolling: Rolling is carried out using a constant micro-tension rolling mill without twisting wire rod.

[0010] S4. Cutting the head and tail after rolling: Set the cutting parameters for flying shear #1, flying shear #2, and flying shear #3;

[0011] S5, Cooling Control: Set water cooling parameters, air cooling parameters, and spinning machine control parameters;

[0012] S6. Compression and binding of wire coils: Since the wire produced by the non-twist wire rolling mill is mostly large and heavy products, and after being coiled at a controlled cooling temperature below 400°C, the coils are relatively loose and must be compressed and bound.

[0013] Specifically, the wire-spinning temperature in step S1 is set to 880℃-960℃. The initial rolling temperature and the wire-spinning temperature are set based on the small temperature drop of the rolled pieces in the roughing and intermediate rolling mills of the high-speed wire rod mill, and the fact that the rolled pieces are heated in the finishing mill.

[0014] Specifically, in step S1, the speed of the furnace exit pinch roll is set to 0.35 m / s, the lead rate of the furnace exit pinch roll is set to 1.0%, and the speed of the furnace exit roller conveyor is set to 0.32 m / s.

[0015] Specifically, the high-pressure water descaling step in step S2 is as follows:

[0016] S21. When removing iron oxide scale from carbon structural steel, the water pressure impact force acting on the surface of the billet should be 0.23-0.26 MPa, the pressure before the nozzle should be 11-12 MPa, and considering the pressure loss of pipelines and valves, the pump station pressure should be 13-14 MPa.

[0017] S22. The distance between the nozzle and the surface of the steel billet is 250-300mm;

[0018] S23. It is better to use an elliptical nozzle, and the sprayed water should have a certain scattering angle α, which is between 20-45°.

[0019] Specifically, the twistless wire rod mill in step S3 is a 45° high-speed twistless mill with a rolling speed greater than 40m / s. The 45° high-speed twistless mill uses small-diameter rolls and high-speed rolling. The main motor of the rolls is a DC motor, which drives the rolls through a speed increaser, a three-gear box, upper and lower connecting shafts, precision bevel gears and helical gears.

[0020] Specifically, the finishing mill of the non-twist wire rod mill is a multi-stand continuous rolling mill, which relies on precise pass design to ensure constant micro-tension rolling during continuous rolling. The pass system sequence of the wire rod is: box-shaped pass - square pass - elliptical pass - round pass - ... - elliptical pass - round pass. That is, except for the first and second passes, the pass design is an alternating arrangement of elliptical and round passes.

[0021] Specifically, the cutting parameters of the #1 flying shear in step S4 are as follows: the #1 flying shear is engaged in a state of cutting the head but not the tail, the #1 flying shear head advance coefficient is 1.10-1.25, and the #1 flying shear head length is ≤150mm;

[0022] The cutting parameters of the #2 flying shear are as follows: the #2 flying shear is engaged in the head-cutting and tail-cutting state; the #2 flying shear head advance coefficient is 1.10-1.15; the #2 flying shear head length is ≤200mm; the #2 flying shear tail lag coefficient is 0.85-0.90; and the #2 flying shear tail length is ≤300mm.

[0023] The cutting parameters for the #3 flying shear are as follows: the #3 flying shear is engaged in the head-cutting mode but not the tail-cutting mode; the #3 flying shear head advance coefficient is 1.10-1.20; the #3 flying shear head length is ≤700mm; and the fragmentation shear advance coefficient is 1.10-1.15.

[0024] Specifically, the water cooling parameters in the controlled cooling process in step S5 are set as follows: the length of the uncooled section at the head is set to 20m, and the backflush water nozzles and backflush air nozzles are turned on in the precooling water cooling box, water cooling box 1, water cooling box 2, and water cooling box 3.

[0025] The air-cooling parameters are set as follows: turn on the fan and set the air-cooling roller speed to 0.34-0.40 m / s;

[0026] The control parameters for the spinning machine are set as follows: the feeding roller of the spinning machine is in the tail position, the feed roller advance rate is 2.0-2.5%, the tail lag rate of the feeding roller is 1.0-1.5%, and the lead rate of the spinning machine is 2.5-3.0%.

[0027] Specifically, in step S6, the compression and binding are as follows: for a coil diameter of 1050mm, the height is 120mm per 100kg before compaction and 100mm per 100kg after compression and binding, and the applied compression force is 100kN per 100kg.

[0028] The present invention has the following beneficial effects:

[0029] The present invention provides a production method for hot-rolled carbon structural steel round bars that reduces the initial rolling temperature, minimizes metal oxidation loss and energy consumption, ensures the strength of the billet, sets standard parameter settings, and employs a die system design to ensure the consistency of the wire rod diameter, avoids wire rod breakage, improves product quality, reduces production costs, and increases production efficiency. Attached Figure Description

[0030] Figure 1 This is a flowchart of the production method of hot-rolled carbon structural steel round bars. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0032] like Figure 1 As shown, a method for producing a hot-rolled round bar of carbon structural steel Q235 with a diameter of 8mm includes the following steps:

[0033] 1. Billet Heating: The initial rolling temperature for carbon structural steel is 900℃, and the wire drawing temperature is set at 880℃. These temperatures are based on the small temperature drop of the rolled pieces in the roughing and intermediate rolling mills of high-speed wire rod mills, and the fact that the rolled pieces are further heated in the finishing mill. Lowering the initial rolling temperature significantly reduces metal oxidation loss and energy consumption. A heating temperature of 900℃ results in 0.5% lower metal burn-off compared to 980℃, while reducing total product energy consumption by 1.16 x 10⁹ J / t, including a 1.3 x 10⁹ J / t reduction in heating energy consumption and a 0.14 x 10⁹ J / t increase in rolling power consumption.

[0034] The speed of the exit pinch rolls is set to 0.35 m / s, the lead rate of the exit pinch rolls is set to 1.0%, the speed of the exit roller table is set to 0.32 m / s, the speed of the steel separating roller table is set to 0.8 m / s, the exit speed of the finishing mill is set to 70 m / s, and the lead rate of the steel separating roller table is set to 1.0%.

[0035] 2. Pre-rolling descaling: High-pressure water descaling is performed; the steps for high-pressure water descaling are as follows:

[0036] S21. When removing iron oxide scale from carbon structural steel, the water pressure impact force acting on the surface of the billet should be 0.26 MPa, the pressure before the nozzle should be 12 MPa, and considering the pressure loss of pipelines and valves, the pump station pressure should be 14 MPa.

[0037] S22. The distance between the nozzle and the surface of the steel billet is 300mm;

[0038] S23. It is better to use an elliptical nozzle, and the sprayed water should have a certain scattering angle α, which is 40°.

[0039] 3. Rolling: The constant micro-tension rolling is carried out using a twistless wire rod mill; the twistless wire rod mill adopts a 45° high-speed twistless mill with a rolling speed greater than 40m / s. The 45° high-speed twistless mill uses small-diameter rolls and high-speed rolling. The main motor of the rolls is a DC motor, which drives the rolls through a speed increaser, a three-gear box, upper and lower connecting shafts, precision bevel gears and helical gears.

[0040] The finishing mill of a twist-free wire rod mill is a multi-stand continuous rolling mill. It relies on precise pass design to ensure constant micro-tension rolling during continuous rolling. The pass system sequence for wire rod is: box pass - square pass - elliptical pass - round pass - ... - elliptical pass - round pass. That is, except for the first and second passes, the pass design alternates between elliptical and round passes. The cross-section rolled through this pass system is circular. The rolled piece smoothly transitions from one cross-section to another, avoiding localized stress caused by severe uneven deformation. It also reduces the sharp edges at the cut end of the rolled piece, resulting in uniform cooling, reduced crack formation, and easier removal of iron oxide scale from the rolled piece surface.

[0041] Because high-speed, non-twisted wire rod finishing mills use constant micro-tension rolling, the cross-sectional dimensions of the de-tensioned sections at the head and tail of the rolled piece will deviate from the nominal cross-sectional dimensions. The length of the de-tensioned section is directly proportional to the tension value, the stand spacing, and the finishing elongation coefficient, and inversely proportional to the required nominal cross-sectional dimension deviation. This deviated section is usually removed before delivery. The deviated section is manually removed on the loose-coil air-cooled conveyor, but this is difficult to do in delayed-type controlled cooling processes due to the lack of insulation and the short length of the section. Furthermore, removing the head section can easily cause coil tangling and deformation, making coil rewinding difficult.

[0042] 4. Cutting the head and tail after rolling: Set the cutting parameters for flying shear #1, flying shear #2, and flying shear #3.

[0043] The cutting parameters of the #1 flying shear are as follows: the #1 flying shear is engaged to cut the head but not the tail; the #1 flying shear head advance coefficient is 1.10-1.25; and the #1 flying shear head length is ≤150mm.

[0044] The cutting parameters of the #2 flying shear are as follows: the #2 flying shear is engaged in the head-cutting and tail-cutting state; the #2 flying shear head advance coefficient is 1.10-1.15; the #2 flying shear head length is ≤200mm; the #2 flying shear tail lag coefficient is 0.85-0.90; and the #2 flying shear tail length is ≤300mm.

[0045] The cutting parameters for the #3 flying shear are as follows: the #3 flying shear is engaged in the head-cutting mode but not the tail-cutting mode; the #3 flying shear head advance coefficient is 1.10-1.20; the #3 flying shear head length is ≤700mm; and the fragmentation shear advance coefficient is 1.10-1.15.

[0046] 5. Cooling control: Set water cooling parameters, air cooling parameters, and spinning machine control parameters.

[0047] The water cooling parameters are set as follows: the length of the uncooled section at the head is set to 20m, and the pre-cooled water cooling box, water cooling box 1, water cooling box 2, and water cooling box 3 are all turned on with the backflush nozzle 1, backflush nozzle 3, backflush air nozzle 1, and backflush air nozzle 3 turned on.

[0048] The air-cooling parameters are set as follows: turn on 2 fans and set the air-cooling roller speed to 0.34-0.40m / s.

[0049] The control parameters for the spinning machine are set as follows: the feeding roller of the spinning machine is in the tail position, the feed roller advance rate is 2.0-2.5%, the tail lag rate of the feeding roller is 1.0-1.5%, and the lead rate of the spinning machine is 2.5-3.0%.

[0050] 6. Compressing and bundling of wire coils: Since the wire produced by the non-twist wire rolling mill is mostly large and heavy products, and after being coiled at a controlled cooling temperature below 400°C, the coils are relatively loose and must be compressed and bundled.

[0051] For a coil with a diameter of 1050mm, the height is 120mm per 100kg before compaction and 100mm per 100kg after compaction. The applied compaction force is 100kN per 100kg.

[0052] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0053] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A method for producing hot-rolled carbon structural steel round bars, characterized in that, Includes the following steps: S1. Steel billet heating: The speed of the tapping rollers is set to 0.35m / s, the lead rate of the tapping rollers is set to 1.0%, and the speed of the tapping roller conveyor is set to 0.32m / s. S2. Pre-rolling descaling: High-pressure water descaling is installed; S3. Rolling: Constant micro-tension rolling is adopted using a twistless wire rod mill; the twistless wire rod mill adopts a 45° high-speed twistless mill with a rolling speed greater than 40m / s. The 45° high-speed twistless mill uses small-diameter rolls for high-speed rolling. The main motor of the small-diameter rolls is a DC motor, which drives the small-diameter rolls through a speed increaser, a three-gear box, upper and lower connecting shafts, precision bevel gears and helical gears; the finishing mill of the twistless wire rod mill is a multi-stand continuous rolling mill, which relies on precise pass design to ensure constant micro-tension rolling during continuous rolling. The pass system sequence of the wire rod is: box-shaped pass - square pass - elliptical pass - round pass - ... - elliptical pass - round pass, that is, except for the first and second passes, the pass design is an alternating arrangement of elliptical and round passes; S4. Cutting the head and tail after rolling: Set the cutting parameters for flying shear #1, flying shear #2, and flying shear #3; S5, Cooling Control: Set water cooling parameters, air cooling parameters and spinning machine control parameters; water cooling parameters are set as follows: the length of the uncooled section at the head is set to 20m, and the backflush water nozzles and backflush air nozzles are turned on in the precooling water cooling box, water cooling box #1, water cooling box #2 and water cooling box #3; The air-cooling parameters are set as follows: turn on the fan and set the air-cooling roller speed to 0.34-0.40 m / s; The control parameters for the spinning machine are set as follows: the feeding roller of the spinning machine is in the tail-clamping state, the lead rate of the feeding roller of the spinning machine is 2.0-2.5%, and the tail-lag rate of the feeding roller of the spinning machine is 1.0-1.5%. S6. Compression and binding of wire coils: Since the wire produced by the non-twist wire rolling mill is mostly large and heavy products, and after being coiled at a controlled cooling temperature below 400°C, the coils are relatively loose and must be compressed and bound.

2. The method for producing hot-rolled carbon structural steel round bars according to claim 1, characterized in that, The high-pressure water descaling step in step S2 is as follows: S21. When removing iron oxide scale from carbon structural steel, the water pressure impact force acting on the surface of the billet is 0.23-0.26 MPa, the pressure before the nozzle is 11-12 MPa, and considering the pressure loss of pipelines and valves, the pump station pressure is 13-14 MPa. S22. The distance between the nozzle and the surface of the steel billet is 250-300mm; S23. An elliptical nozzle is used, and the sprayed water has a certain scattering angle α, which is between 20-45°.

3. The method for producing hot-rolled carbon structural steel round bars according to claim 1, characterized in that, The cutting parameters of the #1 flying shear in step S4 are as follows: the #1 flying shear is engaged in the state of cutting the head but not the tail, the #1 flying shear head advance coefficient is 1.10-1.25, and the #1 flying shear head length is ≤150mm; The cutting parameters of the #2 flying shear are as follows: the #2 flying shear is engaged in the head-cutting and tail-cutting state; the #2 flying shear head advance coefficient is 1.10-1.15; the #2 flying shear head length is ≤200mm; the #2 flying shear tail lag coefficient is 0.85-0.90; and the #2 flying shear tail length is ≤300mm. The cutting parameters of the #3 flying shear are as follows: the #3 flying shear is engaged to cut the head but not the tail; the #3 flying shear head advance coefficient is 1.10-1.20; and the #3 flying shear head length is ≤700mm.

4. The method for producing hot-rolled carbon structural steel round bars according to claim 1, characterized in that, In step S6, the compression and binding are performed as follows: for a coil diameter of 1050mm, the height is 120mm per 100kg before compaction and 100mm per 100kg after compression and binding, with an applied compression force of 100kN per 100kg.

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