Production system and production method of high-ductility ribbed steel bar
Technical Field
The invention relates to a production system and a production method of a steel bar, in particular to a production system and a production method of a high-ductility ribbed steel bar, and belongs to the field of steel bar cold rolling.
Background
With the continuous development of high-speed rail in China, the demand of steel bars used for high-speed rail is also rapidly increased, however, the steel bars used for high-speed rail have special requirements, the steel bars are required to have high ductility and certain tensile strength, the traditional steel bar production comprises hot rolling forming and cold rolling forming, compared with hot rolling forming, cold rolling forming has the characteristics of environmental protection, stability and the like, in cold rolling forming, the adopted wire rod is formed by melting raw materials according to a certain proportion formula, rough rolling, medium rolling, finish rolling, spinning, air cooling or water cooling and the like, in the process of forming the wire rod, in order to improve the tensile strength of the wire rod and the production speed, the processes of air cooling, water cooling or oil cooling and the like are carried out, the hot-formed steel bar subjected to cold treatment at least forms a stress on the surface of the steel bar, and in addition, the tensile strength of the wire rod is 400-800 MPa.
In order to further improve the elongation and tensile strength of steel bar products required for high-speed rail construction, current production equipment is analyzed, and the existing cold-rolled steel bar processes including the patented technology are analyzed, and on the basis, experimental analysis is performed.
Prior to the test, the following patent search and analysis were performed.
The patent application No. 00122927.3 provides a method for manufacturing a low-relaxation-prestress high-strength steel wire, which comprises the process steps of descaling, cold rolling, wire drawing spiral forming and stabilizing heat treatment.
The patent No. 200410013658.2 provides a high-strength low-relaxation cold-rolled ribbed indented bar, its production method and special production line, and its production process includes the procedures of uncoiling, paying-off, descaling, cold-rolling, indentation, heat treatment and wire-rewinding.
The patent application No. 201510945123.7 provides a cold-rolled steel bar processing technology, which comprises the following steps: 1) sending the hot-rolled wire rod into a rolling mill unit for reducing and cold-rolling and generating ribs; 2) carrying out heat treatment on the hot-rolled wire rod subjected to cold rolling in the step 1); 3) straightening the hot-rolled wire rod subjected to the heat treatment in the step 2), cutting to length and collecting.
Patent No. 201610669407.2 provides a method for processing a high-ductility cold-rolled ribbed steel bar, which comprises the following steps: the production method of the cold-rolled steel bar comprises the steps of descaling, reducing, forming, heat treatment, cooling and the like, and application number 201810818442.5 discloses a production method of the cold-rolled steel bar, which comprises the following steps:
pouring molten steel in a steel mould in a steel furnace, and forming hot-rolled steel bars after shaping and cooling;
removing phosphorus from the steel bars in the step one, and introducing the steel bars into a rolling mill for cold rolling and cold twisting;
step three, eliminating cold rolling stress of the steel bar subjected to cold rolling and cold twisting in the step two by a stress eliminator;
and step four, introducing the steel bars for eliminating the cold rolling stress in the step four into complete equipment, removing rust, straightening, rolling and warehousing.
From the above-mentioned methods, it has been found that when the ribbed steel bar is produced from the wire rod by the cold rolling process, the wire rod is produced without combining the inherent characteristics of the purchased product in consideration of the product delivery indexes such as the grain structure, tensile strength, yield strength, elongation, etc. of the processed steel bar. In other words: in the prior art, the characteristics of the product are satisfied by performing heat treatment after cold rolling, and the characteristics of the product before processing are not considered, but actually, in the cold rolling production, the wire rod as a raw material is directly subjected to cold rolling processing, so that the lattice structure of the original wire rod is damaged, the plasticity of the wire rod is reduced, and the strength of the steel bar is also reduced to a certain extent, even if the wire rod is subjected to heat treatment in the subsequent heat treatment, but the temperature of the heat treatment is far lower than the forming temperature of the wire rod when the wire rod is initially manufactured, so that the steel bar subjected to heat treatment after cold rolling processing is difficult to recover to the grain structure after the quenching treatment of the wire rod, in addition, in the heat treatment of the wire rod, the cooling speed of the general wire rod is higher in order to improve the production efficiency, the wire rod is subjected to quenching treatment and is rapidly cooled, the tensile strength of the steel bar is reduced, and the elongation rate is relatively low, however, if the steel bar is used for a high-speed rail viaduct and a ballastless track, the tensile strength and the yield strength, particularly the elongation rate of the steel bar are different from the requirements of a common building, the steel bar used in the high-speed rail construction requires both the increased tensile strength and the increased yield strength and the higher elongation rate, and if the steel bar is directly subjected to cold rolling processing on the original wire rod, the tensile strength and the elongation rate are difficult to be improved even if the heat treatment is performed at the later stage of the rib steel bar forming, so how to further improve the elongation rate on the basis of the existing product indexes is a new problem faced by a cold-rolled steel bar manufacturer.
Disclosure of Invention
Aiming at the characteristic that the requirement on the tensile strength and the elongation rate of a steel bar is high in the construction of a high-speed rail viaduct and a ballastless track, the invention provides a production system and a production method of a high-ductility ribbed steel bar by considering the forming process of a wire rod and the characteristics of high tensile strength and low elongation of the wire rod, and aims to perform cold rolling processing on the steel bar at a certain temperature, reduce the damage degree of a lattice structure of the wire rod in the cold rolling process, reduce the hardness of the steel bar in the cold rolling process, reduce the cold rolling power required in the cold rolling process, save energy, and further improve the elongation rate through secondary heat treatment.
The technical scheme of the invention is as follows: the production system comprises a paying-off machine, a descaling machine, a rolling reducer, a loop, a rolling rib pressing machine, a heat treatment device, a take-up machine and a production line controller, and at least comprises two types of rolling equipment and two types of heat treatment devices, wherein the two types of rolling equipment comprise the rolling reducer and the rolling rib pressing machine, the two types of heat treatment devices comprise a primary heat treatment device and a secondary heat treatment device, the primary heat treatment device and the secondary heat treatment device are respectively arranged at the front position and the rear position of the rolling rib pressing machine, temperature detectors are respectively arranged behind the primary heat treatment device and the secondary heat treatment device, and the primary heat treatment device, the secondary heat treatment temperature and the temperature detectors are connected with the production line controller.
A production method of a high-ductility ribbed steel bar comprises the following steps of unwinding, descaling, rolling and reducing, looping, rolling and rib pressing, heat treatment and winding: the ribbed steel bar rolling production line at least comprises two heat treatment processes, wherein the first heat treatment process is positioned before the rib rolling process, the second heat treatment process is positioned after the rib rolling process, the first heat treatment process is a preheating treatment process, the preheating temperature of the preheating treatment process is lower than 200 ℃, the heat treatment temperature of the second heat treatment process is lower than 180-;
further, the rolling and reducing mill comprises a rolling and reducing mill in the left-right direction and a rolling and reducing mill in the up-down direction, the rolling and rib pressing mill comprises a rolling and rib pressing mill in the left-right direction and a rolling and rib pressing mill in the up-down direction, the rolling and reducing mill and the rolling and rib pressing mill are both provided with paired rollers, and the paired rollers of the last rolling and rib pressing mill are paired die rollers with ribs and/or nicks;
furthermore, a directional device is arranged in front of the rolling reducer, the rolling rib-pressing machine and the heat treatment device, the directional device is one or more pairs of directional rollers in the vertical and/or horizontal directions or a horizontal directional sleeve, and a loop and a steel bar wire steering device for adjusting the looseness of the wires are also arranged between the rolling reducer and the rolling rib-pressing machine;
further, the primary heat treatment device and the secondary heat treatment device are respectively composed of a plurality of high-frequency coils and medium-frequency coils, a plurality of reinforcing steel bar moving stabilizing rollers are respectively arranged in front of the high-frequency coils and the medium-frequency coils, roller shafts of the reinforcing steel bar moving stabilizing rollers are hollow shafts, and cooling water is arranged in the hollow shafts;
furthermore, a V-shaped groove is arranged in the middle of the periphery of the last group of paired die rollers with the pressing ribs and/or the nicks, V-shaped openings of the pair of rollers are arranged oppositely, two side surfaces in the V-shaped groove are in a concave arc shape, the intersecting vertex angle of the chord of the two concave arcs in the V-shaped groove is 90 degrees, two mutually alternately arranged willow-leaf-shaped inclined rib grooves are arranged in the V-shaped groove, the intersecting vertex angle of the chord is in a concave shape, the included angle between the longitudinal middle line of the ribs of the two willow-leaf-shaped inclined rib grooves and the periphery surface of the die roller is respectively 130 degrees at 100 degrees, 130, 145 degrees, wherein a circumferential line formed by intersecting vertex angles of inner chords of the V-shaped grooves and a mold closing line of the upper roller and the lower roller are both provided with a sunken part, the depth of the sunken part is less than 2mm, the distance between middle lines in the rib length direction of the two willowleaf-shaped inclined rib grooves is less than 10mm, and the inclination angles of the two willowleaf-shaped inclined rib grooves in the upper roller and the lower roller are 180 degrees different; furthermore, the steering device is a 90-degree steering device of the reducing steel bar, the steering device is composed of a plurality of arch holes, chords of the arch holes gradually change from the horizontal direction to the vertical direction from the front to the back, and the arch holes are arranged on the wear-resisting plate;
further, the wire rod diameter is less than 15mm, and high ductility ribbed steel bar includes:
1) arranging the wire rod on a pay-off machine and leading the wire rod to a descaler;
2) removing oxidized debris on the surface of the steel bar by using a descaler;
3) rolling and reducing the steel bar wire by using a rolling and reducing machine, wherein the rolling and reducing comprises a rolling and reducing process in the left-right direction and a rolling and reducing process in the up-down direction;
4) preheating the rolled and reduced steel bar wire by using a primary heat treatment device;
5) detecting the temperature of the wire rod treated in the primary heat treatment process, and feeding back information to a production line controller, wherein the production line controller adjusts the temperature of the high-frequency generators;
6) rolling the steel bar wire by using a rolling rib pressing machine, and simultaneously performing rolling rib pressing and/or scoring, wherein the rolling rib pressing and/or scoring comprises a rolling process in the left-right direction and a rolling rib pressing and/or scoring process in the up-down direction, and the rolling rib pressing and/or scoring process is positioned at the last of the rolling rib pressing machine;
7) the secondary heat treatment device carries out secondary heat treatment on the rolled and reduced steel bar wire, and the secondary heat treatment process comprises heating, forced cooling and natural cooling;
8) detecting the temperature of the ribbed steel bars at the tail ends of the intermediate frequency coils in the secondary heat treatment process by using a temperature detector, and adjusting the temperature of the intermediate frequency heaters by using a production line controller according to the detected temperature;
9) winding the ribbed steel bars by using a wire rewinding machine to form a ribbed steel bar coil, and switching among a plurality of ribbed steel bar wire rewinding machines if necessary;
further, the primary heat treatment process is high-frequency coil heating, the secondary heat treatment process is intermediate-frequency coil heating, the temperatures of the high-frequency coils and the intermediate-frequency coils are gradually increased respectively, the temperature rise of the primary heat treatment process is 110-200 DEG/m, and the temperature rise of the secondary heat treatment process is 90-150 DEG/m;
further, the temperature of the forced cooling in the secondary heat treatment step is reduced to 10 to 30 DEG/s, and the forced cooling time is 2 seconds.
By arranging primary preheating after rolling and reducing, although the integral characteristics of the steel bar are not greatly influenced, the yield strength under the cold rolling condition can be maintained, the quenching strength of the steel bar wire rod can be relieved to a certain extent, the lattice defect caused by the cold rolling state of a rolling and reducing machine in the plastic deformation can be reduced to a certain extent, the lattice defect in the subsequent rib rolling process can be reduced, the primary preheating is used for facilitating the forming in the rib rolling process, the power required in the rib rolling process can be reduced to a certain extent, the forming difficulty of the rib rolling process is reduced, the energy is saved, meanwhile, the temperature can be continuously increased on the basis of the primary heat treatment in the secondary heat treatment process, the primary preheating at the temperature lower than 200 ℃ can release the stress caused in the manufacturing of the steel bar wire rod, and under the condition of not influencing the substantial characteristics of the steel bar wire rod and the ribbed steel bar, the lowest temperature of the secondary heat treatment during temperature rise is increased, the temperature rise time of the secondary heat treatment is shortened, and the speed of the secondary heat treatment is accelerated; the steel bar wire steering device is arranged between the rolling reducer and the rolling rib pressing machine, so that the wire rod which is reduced and rolled into the oval structure can be rotated by 90 degrees and then continuously rolled towards the round structure; the cold rolling processing method can be used for cold rolling processing of the steel bar at a certain temperature, the damage degree of the lattice structure of the wire rod in the cold rolling process is reduced, the hardness of the steel bar in the cold rolling process is reduced, the cold rolling power required in the cold rolling process is reduced, the energy is saved, and the elongation is further improved through secondary heat treatment.
Drawings
FIG. 1 is a schematic view of the structure of the production system of the present invention.
FIG. 2 is a schematic view of a plurality of arcuate apertures in the steering apparatus.
FIG. 3 is a schematic view of the structure of a single heat treatment apparatus.
FIG. 4 is a schematic view of the configuration of the rib and/or score line in the peripheral V-groove of one of the last pair of die rollers.
FIG. 5 is a schematic view of the rib and/or score line configuration within the peripheral V-groove of the other of the last pair of die rollers.
FIG. 6 is a schematic longitudinal cross-sectional view of a final set of pairs of die rollers for ribbing and/or scoring.
Fig. 7 is a partial front view structural schematic diagram of a ribbed steel bar.
Fig. 8 is a schematic side view of a ribbed bar.
FIG. 9 is a schematic view of a portion of A-A in FIG. 7 in cross-section.
Fig. 10 is a schematic view of the structure of a ribbed bar.
Fig. 11 is a schematic view of the inner circle radius formed by the arc-shaped arc edge of the steel bar main body of the ribbed steel bar.
Detailed Description
The following detailed description of the embodiments of the present invention will be made with reference to the accompanying drawings. In the following description, the front-rear direction refers to a flow direction of the reinforcing bars, the left-right direction refers to both side surfaces in an advancing direction of the reinforcing bar production line, and the up-down direction refers to the up-down direction in the vertical direction.
The reference numerals in the drawings represent respectively: 10-paying out machine, 11 a-directional sleeve I, 11-descaler, 12 a-directional roller I, 12-vertical rolling reducer, 13 a-directional sleeve II, 13-left-right rolling reducer, 14 a-reinforcing steel bar direction stabilizing roller I, 14 one-time heat treatment device, 15-temperature detector, 16-steering device, 17 a-directional sleeve III, 17-left-right rolling rib press, 18 a-directional roller II, 18-vertical rolling rib press, 19 a-reinforcing steel bar direction stabilizing roller II, 20 a-wire reinforcing steel bar, 20 b-ribbed reinforcing steel bar, 21-flying shear, 22-conveying track machine, 23 a-winding machine I, 23b winding machine II, 24-wear plate, 25-arch hole switching machine, 26-high frequency or intermediate frequency generator, 27-heating coil, 27 a-heat preservation cover, 28-moving stabilizing roller, 29-hollow shaft cooling water pipe, 30a-V type groove side I, 30b-V type groove side II, 31 a-willow leaf-shaped inclined rib groove I, 31 b-willow leaf-shaped inclined rib groove II, 32-middle line, 33-vertex angle concave part and 34-mold closing concave part.
The technical scheme of the invention is as follows: fig. 1 is a schematic structural view of a system for producing a high-ductility ribbed steel bar 20b according to the present invention. The production system comprises a paying-off machine 10, a descaling machine 11, a rolling reducing mill, a loop, a rolling rib pressing machine, a heat treatment device, a take-up machine and a production line controller in the prior art, the production system at least comprises two types of rolling equipment and two types of heat treatment devices, the two types of rolling equipment comprise the rolling reducing mill and the rolling rib pressing machine, the two types of heat treatment devices comprise a primary heat treatment device 14 and a secondary heat treatment device, the primary heat treatment device 14 and the secondary heat treatment device are respectively arranged at the front and rear positions of the rolling rib pressing machine, a temperature detector 15 is respectively arranged behind the primary heat treatment device 14 and the secondary heat treatment device, and the primary heat treatment device 14, the secondary heat treatment temperature and the detector are connected with the production line controller.
A production method of a high-ductility ribbed steel bar 20b comprises the steps of unwinding, descaling, rolling and reducing, looping, rolling and rib pressing, heat treatment and winding, wherein the ribbed steel bar 20b at least comprises two heat treatment steps in the rolling process, wherein the primary heat treatment process is positioned before the rib rolling process, the secondary heat treatment process is positioned after the rib rolling process, the primary heat treatment process is a preheating treatment process, the preheating temperature of the preheating treatment process is lower than 200 ℃, the heat treatment temperature of the secondary heat treatment process is lower than 180 ℃ and 700 ℃, the diameter of the rolled wire steel bar 20a is reduced by 18-28%, the yield strength and the tensile strength of the ribbed steel bar 20b produced by the production method of the ribbed steel bar 20b with the primary heat treatment process are respectively 550-580MPa and 610-660MPa, and the elongation is 13-18%.
TABLE 1 examples of product characteristics compared to existing lines using the production line of the present invention
The rolling and reducing mill comprises a rolling and reducing mill 13 in the left-right direction and a rolling and reducing mill 12 in the up-down direction, the rolling and rib pressing mill comprises a rolling and rib pressing mill 17 in the left-right direction and a rolling and rib pressing mill 18 in the up-down direction, paired rollers are arranged on the rolling and reducing mill and the rolling and rib pressing mill, and paired rollers of the last rolling and rib pressing mill are paired die rollers with ribs and/or nicks.
The rolling diameter reducer, the rolling rib pressing machine and the heat treatment device are provided with orienting devices in front, wherein the orienting devices are one or more pairs of positioning rollers in the vertical and/or left-right directions or horizontal positioning sleeves, 11a is a first positioning sleeve and is positioned in front of the descaler 11, and a first positioning sleeve 12a is a horn-shaped sleeve structure in the horizontal direction, so that the wire coiling can shake in the wire paying-off process, and the shaking phenomenon can be stabilized by the aid of the horn-shaped sleeve structure; 12a is a first positioning roller and is positioned in front of the rolling reducer 12 in the vertical direction; 13a is a second positioning sleeve which is positioned in front of the rolling reducing mill 13 in the left-right direction; 14a is a first reinforcing steel bar direction stabilizing roller and is positioned in front of each high-frequency heating coil in the primary heat treatment device 14; 17a is a third positioning sleeve which is positioned in front of the rolling rib pressing machine 17 in the left-right direction; 18a is a second positioning roller and is positioned in front of the rolling rib pressing machine 18 in the vertical direction; 19a is a reinforcing steel bar direction stabilizing roller II which is positioned in front of each intermediate frequency heating coil in the secondary heat treatment device.
A loop and a steel bar wire steering device 16 for adjusting the looseness of the wire rod are arranged between the rolling reducing mill and the rolling rib pressing mill.
The primary heat treatment device 14 and the secondary heat treatment device are respectively composed of a plurality of high frequency and intermediate frequency coils, and fig. 3 is a schematic structural view of a single heat treatment device. The primary heating device and the secondary heating device are respectively composed of a plurality of single heat treatment devices, heating coils 27 of the single heat treatment devices are arranged into a line according to needs and are respectively controlled, heating temperature is set in the high-frequency or intermediate-frequency generator 26, corresponding adjustment is carried out by using a controller, 27a is a heat preservation cover of the heating device, a plurality of reinforcing steel bar moving stabilizing rollers 28 are respectively arranged in front of the high-frequency or intermediate-frequency heating coils 27 arranged into a row, roller shafts of the reinforcing steel bar moving stabilizing rollers 28 are hollow shafts, cooling water is arranged in the hollow shafts, 29 is a hollow shaft cooling water pipe, and the cooling water circularly flows in the hollow shaft cooling water pipes, so that the rolling of the rollers is prevented from being hindered by thermal expansion of the roller shafts.
FIG. 4 is a schematic view of the configuration of the rib and/or score line in the peripheral V-groove of one of the last pair of die rollers. FIG. 5 is a schematic view of the rib and/or score line configuration within the peripheral V-groove of the other of the last pair of die rollers. FIG. 6 is a schematic longitudinal cross-sectional view of a final set of pairs of die rollers for ribbing and/or scoring. The middle of the periphery of the last group of rollers in the paired die rollers with the pressing ribs and/or nicks is provided with a V-shaped groove, the V-shaped openings of the pair of rollers are oppositely arranged, two side surfaces of the V-shaped groove are in a concave arc shape, two side surfaces of the V-shaped groove are a V-shaped groove side surface one 30a and a V-shaped groove side surface two 30b, the chord intersection vertex angle of the two concave arc shapes in the V-shaped groove is 90 degrees, two mutually alternately arranged willow-leaf-shaped inclined rib grooves are arranged in the V-shaped groove, specifically, the vertex angle of the chord intersection of the first willow-leaf-shaped inclined rib groove 31a and the second willow-leaf-shaped inclined rib groove 31b is concave, 33 is a vertex angle concave part, the included angle between the rib length direction middle line 32 of the two willow-leaf-shaped inclined rib grooves and the peripheral surface of the die rollers is respectively at 130 degrees and 145 degrees, the position depth of the, the circumference line formed by the intersecting vertex angles of the inner chords of the V-shaped groove and the die assembly line of the upper roller and the lower roller are both provided with a sunken part 34 which is a die assembly sunken part, the depth of the sunken part is less than 2mm, the distance between the middle lines in the rib length direction of the two salix-leaf-shaped inclined rib grooves is less than 10mm, and the inclination angles of the two salix-leaf-shaped inclined rib grooves in the upper roller and the lower roller are different by 180 degrees.
The main body of the steel bar processed by the roller die is a tetrahedron with four arc-shaped protruding surfaces, the diagonal parts protrude, the heights of two diagonal parts are consistent with the heights of the willow-leaf-shaped inclined ribs, the diagonal protruding parts are intersected with the two inclined willow-leaf-shaped inclined ribs, and the other two diagonal protruding parts are provided with die closing sunken parts to form independent protruding parts which are not intersected with the willow-leaf-shaped inclined ribs.
The temperature detector 15 is an infrared temperature detector 15.
The steering device 16 is a 90-degree steering device 16 for reducing the diameter of the steel bar, and fig. 2 is a structural schematic diagram of a plurality of arch holes in the steering device. The turning means 16 is constituted by a plurality of arcuate holes 25a, the chords of the plurality of arcuate holes 25a gradually turning from the horizontal direction to the vertical direction from the front to the rear, the arcuate holes 25a being provided on the wear plate 24.
The wire rod diameter is less than 15mm, and the high ductility ribbed steel bar 20b includes:
1) arranging the wire rod on a pay-off machine 10 and leading the wire rod to a descaler 11;
2) removing oxidized debris on the surface of the steel bar by using a descaler 11;
3) rolling and reducing the steel bar wire by using a rolling and reducing machine, wherein the rolling and reducing comprises a rolling and reducing process in the left-right direction and a rolling and reducing process in the up-down direction;
4) preheating the rolled and reduced steel bar wire by using a primary heat treatment device 14;
5) detecting the temperature of the wire rod treated in the primary heat treatment process, and feeding back information to a production line controller, wherein the production line controller adjusts the temperature of the high-frequency generators;
6) rolling the steel bar wire by using a rolling rib pressing machine, and simultaneously performing rolling rib pressing and/or scoring, wherein the rolling rib pressing and/or scoring comprises a rolling process in the left-right direction and a rolling rib pressing and/or scoring process in the up-down direction, and the rolling rib pressing and/or scoring process is positioned at the last of the rolling rib pressing machine;
7) the secondary heat treatment device carries out secondary heat treatment on the rolled and reduced steel bar wire, and the secondary heat treatment process comprises heating, forced cooling and natural cooling;
8) detecting the temperature of the ribbed steel bars 20b at the tail ends of the intermediate frequency coils in the secondary heat treatment process by using a temperature detector 15, and adjusting the temperature of the intermediate frequency heaters by using a production line controller according to the detected temperature;
9) the ribbed reinforcing steel bar 20b is wound by a wire winding machine to form a coil of the ribbed reinforcing steel bar 20b, a flying shear 21 and a conveying track switching machine 22 are arranged in front of a plurality of wire winding machines 20b in the prior art as necessary, and the winding switching is carried out among the plurality of wire winding machines under the control of a production line controller.
In this embodiment, a first winding machine 23a and a second winding machine 23b are provided, and the ribbed bars 20b are wound on the first winding machine 23a and the second winding machine 23b by the flying shears 21 and the transfer track switcher 22 in turn.
Fig. 6 is a schematic structural view of a single heat treatment apparatus. The heat treatment apparatus is composed of a plurality of heat treatment apparatuses, wherein the primary heat treatment process is high-frequency coil heating, the secondary heat treatment process is intermediate-frequency coil heating, the temperatures of the high-frequency coils and the intermediate-frequency coils are respectively and gradually increased, the temperature rise of the primary heat treatment process is 110 DEG/m and 200 DEG/m, and the temperature rise of the secondary heat treatment process is 90-150 DEG/m.
The temperature of the forced cooling in the secondary heat treatment process is reduced to 10-30 DEG/s, and the forced temperature reduction time is 2 seconds.
By arranging the primary preheating after the rolling and reducing, although the integral characteristics of the steel bar are not greatly influenced, the yield strength under the cold rolling condition can be maintained, the quenching strength of the steel bar coil can be relieved to a certain extent, the lattice defect caused by the cold rolling state of the rolling and reducing machine in the plastic deformation can be reduced to a certain extent, the lattice defect in the subsequent rib rolling process can be reduced, the primary preheating is used for facilitating the forming in the rib rolling process, the power required in the rib rolling process can be reduced to a certain extent, the forming difficulty of the rib rolling process is reduced, the energy is saved, meanwhile, the temperature can be continuously increased on the basis of the primary heat treatment in the secondary heat treatment process, the primary preheating at the temperature lower than 200 ℃ can release the stress caused in the manufacturing of the steel bar coil, and under the condition that the substantial characteristics of the steel bar coil and the ribbed steel bar 20b are not influenced, the lowest temperature of the secondary heat treatment during temperature rise is increased, the temperature rise time of the secondary heat treatment is shortened, and the speed of the secondary heat treatment is accelerated; the steel bar wire steering device 16 is arranged between the rolling reducer and the rolling rib pressing machine, so that the wire rod which is reduced and rolled into the oval structure can be rotated by 90 degrees and then continuously rolled towards the round structure; the cold rolling processing method can be used for cold rolling processing of the steel bar at a certain temperature, the damage degree of the lattice structure of the wire rod in the cold rolling process is reduced, the hardness of the steel bar in the cold rolling process is reduced, the cold rolling power required in the cold rolling process is reduced, the energy is saved, and the elongation is further improved through secondary heat treatment.
The invention provides another technical scheme that: a production system of a ribbed steel bar, comprising a paying out machine, a descaling machine, a rolling reducing mill, a loop, a rolling rib press, a heat treatment device, a take-up machine and a production line controller in the prior art, wherein the production system comprises at least two types of rolling equipment, which is different from the production system of the high-ductility ribbed steel bar in the above embodiment in that the heat treatment device is not limited to the above two types of heat treatment devices: the primary heat treatment apparatus and the secondary heat treatment apparatus are the same in that the rolling facility may adopt the rolling facility in the above-described embodiment. The rolling and reducing mill comprises a rolling and reducing mill in the left-right direction and a rolling and reducing mill in the up-down direction, the rolling and reducing mill comprises a rolling and rib pressing machine in the left-right direction and a rolling and rib pressing machine in the up-down direction, paired rollers are arranged on the rolling and reducing mill and the rolling and rib pressing machine, the paired rollers of the last rolling and rib pressing machine are paired die rollers with ribs and/or nicks, a V-shaped groove is arranged in the middle of the periphery of the last paired die rollers with the ribs and/or the nicks, V-shaped openings of the paired rollers are oppositely arranged, two side faces in the V-shaped groove are in a concave arc shape, two mutually alternately arranged willow-leaf-shaped inclined rib grooves are arranged in the V-shaped groove, the intersecting vertex angle of a chord is in a concave shape, and a circumferential line formed by the intersecting vertex angle of the inner chord of the V-shaped groove and a die.
In the specific implementation, the included angles between the middle lines of the two salix-leaf-shaped inclined rib groove rib length directions and the outer peripheral surface of the die roller are respectively 130 degrees and 145 degrees, the chord intersection vertex angle of the two concave arcs in the V-shaped groove is 90 degrees, the depth of the concave part is less than 2mm, the distance between the middle lines of the two salix-leaf-shaped inclined rib grooves in the rib length directions is less than 10mm, and the difference between the inclined angles of the two salix-leaf-shaped inclined rib grooves in the upper roller and the lower roller is 180 degrees.
A production method of a ribbed steel bar comprises a wire unwinding process, a descaling process, a rolling reducing process, a loop, a rolling rib pressing process, a heat treatment process and a wire winding process, and is different from the production method of the high-ductility ribbed steel bar in the embodiment in that the production method comprises at least two heat treatment processes, wherein the rolling rib pressing process comprises: rolling the steel bar wire by using a rolling rib pressing machine, and simultaneously rolling and pressing ribs and/or nicks, wherein the rolling and pressing ribs and/or nicks comprise a rolling process in the left-right direction and a rolling and pressing rib and/or nick process in the up-down direction; the rolling and reducing mill comprises a rolling and reducing mill in the left-right direction and a rolling and reducing mill in the up-down direction, the rolling and reducing mill comprises a rolling and rib pressing machine in the left-right direction and a rolling and rib pressing machine in the up-down direction, paired rollers are arranged on the rolling and reducing mill and the rolling and rib pressing machine, the paired rollers of the last rolling and rib pressing machine are paired die rollers with ribs and/or nicks, a V-shaped groove is arranged in the middle of the periphery of the last paired die rollers with the ribs and/or the nicks, V-shaped openings of the paired rollers are arranged oppositely, two side faces in the V-shaped groove are in a concave arc shape, two mutually alternately arranged willow-leaf-shaped inclined rib grooves are arranged in the V-shaped groove, the intersecting vertex angle of a chord is in a concave shape, and a circumferential line formed by the intersecting vertex angle of the inner chord of the V-shaped groove and a die assembly line.
In the specific implementation, the included angles between the middle lines of the two salix-leaf-shaped inclined rib groove rib length directions and the outer peripheral surface of the die roller are respectively 130 degrees and 145 degrees, the chord intersection vertex angle of the two concave arcs in the V-shaped groove is 90 degrees, the depth of the concave part is less than 2mm, the distance between the middle lines of the two salix-leaf-shaped inclined rib grooves in the rib length directions is less than 10mm, and the difference between the inclined angles of the two salix-leaf-shaped inclined rib grooves in the upper roller and the lower roller is 180 degrees.
A ribbed rebar comprising: the steel bar body is a tetrahedron, each face of the steel bar body is a convex arc, the four faces of the steel bar body comprise a first face, a second face, a third face and a fourth face, the first face, the second face, the third face and the fourth face sequentially surround the central line of the steel bar body and enclose the tetrahedron, the first face and the second face are provided with two willow-leaf-shaped inclined ribs which are alternately arranged, and the third face and the fourth face are provided with two willow-leaf-shaped inclined ribs which are alternately arranged; and a convex diagonal part is formed between every two adjacent surfaces, the diagonal part between the first surface and the second surface is intersected with the salix leaf-shaped inclined ribs of the first surface and the second surface, and the diagonal part between the third surface and the fourth surface is intersected with the salix leaf-shaped inclined ribs of the third surface and the fourth surface. Namely, the ribbed steel bar includes: the reinforcing bar main part, it is the tetrahedron, every face of reinforcing bar main part is convex circular-arc, and the diagonal portion protrusion, two diagonal portions height wherein can be unanimous with willow leaf form slope rib height, two diagonal portions intersect with the willow leaf form slope rib of two slopes, and two diagonal portions form through the joint line depressed part and are independent bulge form, do not intersect with willow leaf form slope rib in addition.
In the embodiment of the present invention, the ribbed steel bar may be prepared by the above-mentioned production system, production method, production system and production method of the ribbed steel bar, but is not limited thereto. The ribbed steel bar prepared by the production system and the production method of the ribbed steel bar has the characteristics that the shape characteristics are different from the shape and the structure of the steel bar in the national ferrous metallurgy industry standard YB/T4657-2018 reinforced concrete four-sided rib steel bar, and compared with the steel bar in the national ferrous metallurgy industry standard YB/T4657-2018 reinforced concrete four-sided rib steel bar, the ribbed steel bar has the appearance which is more inclined to be cylindrical, the transverse ribs are in the shape of willow leaves, and the two willow leaf-shaped inclined ribs are alternately arranged. Because adopted different appearance structure characteristics, the ribbed steel bar of this application has following unique advantage: 1. has the characteristic of easy alignment. 2. In the middle of using ribbed steel bar welding reinforcing bar net, be partial to columniform ribbed steel bar, no matter what position is in to ribbed steel bar's rotation angle, can both carry out good welding, reduced the construction degree of difficulty, difficult construction problem that appears has improved the reliability of reinforced concrete product. 3. The steel bar welding device has the characteristic of easy bending, and can easily bend the steel bars at any angle into a rectangular ring in the process of welding the ribbed steel bars into the steel bar cylinder, thereby facilitating construction.
In a specific implementation, a diagonal portion between the second surface and the third surface is separated from the salix leaf-shaped inclined ribs of the first surface and the second surface and the salix leaf-shaped inclined ribs of the third surface and the fourth surface, respectively. The heights of the salix leaf-shaped inclined ribs on the first surface and the second surface, the salix leaf-shaped inclined ribs on the third surface and the fourth surface are less than 2 mm. The height of the first surface, the height of the second surface, the height of the third surface, and the height of the fourth surface are the same as the height of the opposite corner. The chord intersection vertex angle of the two circular arcs of the willow-leaf-shaped inclined rib is 90 degrees. The included angles between the middle line of the two salix-shaped inclined rib groove ribs in the length direction and the axis of the steel bar main body are different and are respectively between 40 and 70 degrees.
The inclination angles of the salix leaf-shaped inclined ribs on the first surface and the second surface and the salix leaf-shaped inclined ribs on the third surface and the fourth surface are different by 180 degrees.
The pitch of the middle lines in the rib length direction of the salix leaf-shaped inclined rib grooves which are alternately arranged is less than 10 mm.
Referring to fig. 7, 8, 9, 10 and 11, the inclined ribs of the ribbed steel bar are in a shape of a willow leaf, and each inclined rib should not longitudinally intersect with other inclined ribs.
The inclined ribs are uniformly distributed along the circumference of the cross section of the ribbed steel bar, wherein the inclination angles of the willow-leaf-shaped inclined ribs on two sides in the ribbed steel bar are opposite, namely the directions of the willow-leaf-shaped inclined ribs on every two opposite surfaces of the steel bar main body are opposite.
The included angles β 1, β 2 between the central line of two adjacent oblique ribs in the ribbed steel bar and the longitudinal axis of the ribbed steel bar are different and are respectively between 40 and 70 degrees.
The distance between two adjacent oblique ribs in the ribbed steel bar is l1, and the distance between two oblique ribs separated by one oblique rib is l1+ l2, wherein l1 and l2 are equal, namely l 1-l 2.
The oblique angle α between any two sides of the inclined rib and the surface of the ribbed steel bar is not less than 40 degrees, and the inclined rib and the surface of the ribbed steel bar are intersected in an arc shape.
The sum of the inclined rib gaps of the ribbed steel bars should be not more than 25 percent of the nominal perimeter (Sigma f)i≤0.25πd)。
The relative inclined rib area fr is determined by equation (1):
wherein the formula is as follows:
K=4;
FR: the longitudinal cross-sectional area of a rib in square millimeters (mm)2);
β, the included angle between the inclined rib and the axis of the steel bar is degree (degree);
d: nominal diameter of the rebar in millimeters (mm);
l: oblique rib spacing in millimeters (mm);
l=l1=l2;
sinβ=(sinβ1+sinβ2)/2。
the inner circle radius R is formed by the convex arc-shaped arc edges of each surface of the steel bar main body.
In some embodiments, the dimensions, weight and tolerances of the ribbed bars are as follows:
according to the embodiment of the invention, due to the appearance characteristics of the circular arc four-side ribs, the steel bar is less prone to steel falling in the forming rolling groove during the production of the steel bar with two sides in the rolling process, 3000 tons of steel is produced at present without steel falling after the four-side ribs are adopted, and the steel bar is a good factor for stable operation in the production process, which is a prominent characteristic.
The performance statistics of the ribbed steel bar after straightening in the embodiment is as follows:
performance statistics after straightening of reinforcing steel bars with ribs on two sides in the prior art is as follows:
by comparing the strength of the ribbed steel bar of the embodiment before and after straightening with that of the double-sided rib of the prior art, the tensile strength of the ribbed steel bar and the double-sided rib after straightening are not changed much, but the yield strength of the ribbed steel bar of the embodiment is reduced by less than that of the double-sided rib, the average yield strength of the ribbed steel bar of the embodiment after straightening is slightly higher than that of the double-sided rib steel bar by about 15MPA, and the yield strength of the ribbed steel bar after straightening is reduced to 20-40MPA, wherein the ribbed steel bar of the embodiment is generally 20-30MPA, and the double-sided rib is generally 25-40MPA, and the average yield strength is also respectively beyond the range and is larger than.
The ribbed rebar weld of this example compares with the two-sided ribbed rebar weld:
and (3) experimental comparison of welding efficiency:
2# mesh welding machine:
1# mesh welding machine:
from experimental statistics, the ribbed steel bar of the embodiment improves the production efficiency by about 6.9% compared with a double-face rib on a No. 2 mesh welding machine. The improvement on the 1# mesh welding machine is about 7.5%.