Slitting and rolling method of reinforcing steel bar for continuous equal-height threaded rib anchor rod

Abstract

The invention relates to the technical field of metallurgy, in particular to a slitting rolling method of a steel bar for a continuous equal-height threaded rib anchor rod, which comprises the following steps of: heating a steel billet, and feeding the heated steel billet into a rough rolling area, an intermediate rolling area, a pre-finish rolling area and a finish rolling area; a slitting and rolling pass system adopted in the finish rolling area comprises a K6 flat roller, a K5 vertical box hole, a K4 symmetrical flat box pre-slitting hole, a K3 symmetrical flat box slitting hole, a K2 flat elliptical hole with groove bottom convexity and a K1 threaded rib anchor rod steel bar finished product hole. Two segmentation loop devices are adopted between K3-K2 and between K2-K1, and the segmentation line difference is controlled to be not larger than 0.3%; twice controlled cooling is carried out in the slitting rolling process; the temperature after primary controlled cooling tempering refers to the temperature of a finish rolling inlet, and the temperature range is 930-950 DEG C; and the temperature after secondary control cooling and tempering refers to the temperature on a cooling bed, and the temperature range is 810-830 DEG C. The rolling method is efficient, and the prepared steel bar for the continuous equal-height threaded rib anchor rod is good in mechanical property.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy, and particularly relates to a splitting rolling method for steel bars used for continuous equal-height threaded rib bolts. Background Art

[0002] With the reform of the support technology for coal mine roadways, bolt support has become the main support means for mine roadway support. In order to overcome the problem that the strength of the tail of ordinary bolt steel bars is relatively low due to the need for extrusion and round rolling of the tail, and the ultimate bearing capacity of the bolt tail is lower than that of the bolt body part, steel bars used for continuous equal-height threaded rib bolts have emerged as the times require.

[0003] The steel bars used for continuous equal-height threaded rib bolts have the characteristics of high transverse rib height, good symmetry and uniformity of transverse ribs on the upper and lower surfaces, good fullness at the end of the transverse ribs, and high dimensional accuracy. There is no need to specially process the bolt tail like ordinary threaded steel bolts. Threaded connectors with internal threads can be screwed on any cross-section of the whole steel bar for connection, ensuring the consistency of strength throughout the length of the bolt, solving the contradiction that the bearing capacity of the bolt tail of ordinary bolts is lower than that of the bolt body, and saving energy and materials at the same time. The requirement for the transverse rib height of the steel bars used for continuous equal-height threaded rib bolts is very high, with a minimum requirement of more than 1.3 mm, and the bottom width of the transverse rib is generally 5.2 - 6.2 mm. To meet the quality requirements of the steel bars used for continuous equal-height threaded rib bolts, the steel bars used for continuous equal-height threaded rib bolts have always been produced by single wire. Its production process route adopts the conventional oval-round pass system, and the finished product quality is unstable, and problems such as insufficient fullness of the transverse ribs are likely to occur. Moreover, problems such as thread stripping will occur during subsequent deep processing and use.

[0004] With the development of society, the market demand for steel bars used for continuous equal-height threaded rib bolts increases year by year. The hot-rolled ribbed steel bars used for continuous equal-height rib bolts are produced by single wire. Compared with the splitting rolling of threaded steel, the production efficiency is relatively low, and the rolling processing cost is relatively high. Although the comprehensive benefits of the hot-rolled ribbed steel bars used for continuous equal-height rib bolts are not worse than those of threaded steel, in order to further enhance its market competitiveness and for the purpose of energy conservation and consumption reduction, it is very necessary to develop the splitting rolling process technology for steel bars used for continuous equal-height threaded rib bolts.

[0005] There are the following technical difficulties in the development of the splitting rolling process technology for steel bars used for continuous equal-height threaded rib bolts: (1) The hot-rolled ribbed steel bars used for equal-height threaded rib bolts require good fullness at the end of the transverse ribs. Therefore, the selection and design of the pass, especially the selection and design of the K3 pass, are crucial; (2) The symmetry of the transverse ribs on the upper and lower two surfaces should be good. What needs to be solved is the consistency problem of the stock shapes of the two wires, especially the consistency problem of the left and right fullness of the K2 stock. Therefore, the design of the guide is very important; (3) Dimensional accuracy problems, including the dimensional difference between two lines and the dimensional differences among the head, middle, and tail. Since the dimensional requirements for the equal-height threaded rib anchor bar steel are different from those of threaded steel and the dimensional requirements are high, the use of the splitting loop and the adjustment of loop parameters are very crucial. Summary of the Invention

[0006] Aiming at the technical problem of low production efficiency in the single-line production of steel bars for continuous equal-height threaded rib anchor bars, the present invention provides a splitting rolling method for steel bars for continuous equal-height threaded rib anchor bars. Through the design of splitting pass, the design of guide guards, and the optimized design of the splitting loop, the stable production of the splitting rolling process for steel bars for continuous equal-height threaded rib anchor bars is realized. At the same time, through the coupling application of splitting rolling and two-stage controlled cooling (controlling cooling during rolling and when entering the cooling bed) in the production of equal-height rib anchor bar steel, an innovative production path with high efficiency, low cost, and high quality is opened up for steel bars for continuous equal-height threaded rib anchor bars.

[0007] The technical solution of the present invention is as follows: Provide a splitting rolling method for steel bars for continuous equal-height threaded rib anchor bars. After the billet is heated, it enters the rough rolling, medium rolling, pre-finishing rolling, and finishing rolling areas. The splitting rolling pass system adopted in the finishing rolling area is K6 flat roll + K5 vertical box pass + K4 symmetric flat box pre-splitting pass + K3 symmetric flat box splitting pass + K2 flat ellipsoidal pass with groove bottom convexity + K1 finished product pass for threaded rib anchor bar steel; full-rolling guide guards are adopted at the inlets of K1-K6, and double-row rolling guide guards are adopted for K1; two splitting loop devices are adopted between K3-K2 and between K2-K1, and the splitting line difference is controlled to be not greater than 0.3%; Two-stage controlled cooling is carried out during the splitting rolling process: the temperature after the first controlled cooling tempering refers to the temperature at the inlet of the finishing rolling, and the temperature range of the temperature at the inlet of the finishing rolling is 930-950 °C; the temperature after the second controlled cooling tempering refers to the temperature when entering the cooling bed, and the temperature range of the temperature when entering the cooling bed is 810-830 °C; The specifications of the prepared steel bars for continuous equal-height threaded rib anchor bars include Φ18mm and Φ20mm.

[0008] Furthermore, when the billet is heated, the furnace gas temperature in the soaking section of the heating furnace is controlled at 1080 °C - 1130 °C, and the heating time ≥ 1 hour.

[0009] Furthermore, the starting rolling temperature after the billet is heated is 960-1000 °C.

[0010] Furthermore, in the finishing rolling area, high-speed steel rolls are used for the rolling mill of the K1 finished product pass for threaded rib anchor bar steel, tungsten carbide rolls are used for the rolling mill of the K2 flat ellipsoidal pass with groove bottom convexity, high-boron steel rolls are used for the rolling mill of the K3 symmetric flat box splitting pass, and high-boron steel rolls are used for the rolling mill of the K4 symmetric flat box pre-splitting pass.

[0011] For the steel bars used in continuously equal-height threaded rib anchor bolts, the height requirement of the transverse ribs is high, and problems such as K1 bursting and chipping may occur. Therefore, the selection of the material for the K1 roll is very crucial. Conventional tungsten carbide materials and high-boron steel materials are prone to grooving and chipping during roll turning and rib washing, and there are processing defects. The high-speed steel roll used for K1 has a moderate hardness and is easy to process.

[0012] Furthermore, the roll phase connecting shaft of the finished hole of the K1 threaded rib anchor bolt steel bar adopts a crankshaft-type connecting shaft.

[0013] Furthermore, when preparing the steel bars for continuously equal-height threaded rib anchor bolts with a specification of Φ18mm, the parameters of the K3 symmetric flat box splitting hole are: hole height h = 18mm, hole width B = 50.19mm, roll gap S = 1.6mm, the length of the bottom plane of the flat box-shaped hole groove is 12.12mm, the splitting wedge angle is 56°, the splitting apex radius R = 0.6mm, and the outer fillet radius r = 2.5mm.

[0014] Furthermore, when preparing the steel bars for continuously equal-height threaded rib anchor bolts with a specification of Φ20mm, the parameters of the K3 symmetric flat box splitting hole are: hole height h = 19.8mm, hole width B = 58.18mm, roll gap S = 1.9mm, the length of the bottom plane of the flat box-shaped hole groove is 11.67mm, the splitting wedge angle is 56°, the splitting apex radius R = 0.47mm, and the outer fillet radius r = 2.5mm.

[0015] Furthermore, the set height of the loop of the two splitting loopers between K3 and K2 is 180 - 200mm, and the loop adjustment delay is 200 - 400ms; the set height of the loop of the two splitting loopers between K2 and K1 is 190 - 220mm, and the loop adjustment delay is 300 - 400ms; the loops between K3 and K2 and the loops between K2 and K1 are dedicated to specific use.

[0016] Furthermore, double-length flying shear cutting is performed between finish rolling and cooling on the cooling bed.

[0017] Furthermore, natural aging is carried out after the cooling on the cooling bed is completed.

[0018] The beneficial effects of the present invention are as follows: The present invention provides a split rolling method for steel bars used in continuously equal-height threaded rib bolts. Compared with the traditional single-line production, the split rolling method has obvious advantages: it can effectively improve production efficiency, significantly increase the output per machine hour, increase the output, especially when producing small-sized products such as Φ18mm and Φ20mm, save investment and production costs. The split rolling reduces the number of stands, lowers power consumption, shortens the rolling rhythm, thereby reducing idle consumption, increasing the output per machine hour, and reducing various consumptions. Moreover, by using split rolling, the heating temperature of the billet, fuel consumption, and power consumption can be reduced, thus reducing production costs. The present invention adopts a split rolling pass system of K6 flat roll + K5 vertical box pass + K4 symmetric flat box pre-split pass + K3 symmetric flat box split pass + K2 flat oval pass with groove bottom convexity + K1 finished pass for threaded rib bolt steel bars, and a full-rolling guide device is used at the entrances of K1 to K6. The steel bars used in continuously equal-height threaded rib bolts have high dimensional accuracy and good end filling degree. The hot-rolled ribbed steel bars used in continuously equal-height threaded rib bolts prepared have refined grains and good comprehensive mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is the roll pass drawing of the K6 flat roll used in the finishing area of the present invention.

[0021] Figure 2 It is the roll pass drawing of the K5 vertical box pass used in the finishing area of the present invention.

[0022] Figure 3 It is the roll pass drawing of the K4 symmetric flat box pre-split pass used in the finishing area of the present invention.

[0023] Figure 4 It is the roll pass drawing of the K3 symmetric flat box split pass used in the finishing area of the present invention.

[0024] Figure 5 It is the roll pass drawing of the K2 flat oval pass with groove bottom convexity used in the finishing area of the present invention.

[0025] Figure 6 It is the roll pass drawing of the K1 finished pass for threaded rib bolt steel bars used in the finishing area of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] To enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0027] Embodiment 1 A splitting rolling method for steel bars used in continuous equal-height threaded rib anchor bolts, including billet heating, rough rolling, medium rolling, pre-finishing rolling, primary controlled cooling, finishing rolling, secondary controlled cooling, multiple-length flying shear cutting, cooling on the cooling bed, and natural aging, and finally preparing steel bars with a diameter of Φ18mm for continuous equal-height threaded rib anchor bolts; Among them, when heating the billet, the furnace gas temperature in the soaking section of the heating furnace is controlled at 1080°C - 1130°C, and the heating time is ≥1 hour; After the billet is heated, it enters the rough rolling, medium rolling, pre-finishing rolling, and finishing rolling areas. The starting rolling temperature is set at 985°C; the entrance temperature of the finishing rolling is 950°C. The roll pass system used in the finishing rolling stage is a splitting rolling pass system of K6 flat roll + K5 vertical box pass + K4 symmetric flat box pre-splitting pass + K3 symmetric flat box splitting pass + K2 flat elliptical pass with a grooved bottom convexity + K1 finished product pass for threaded rib anchor bolt steel bars (as Figures 1-6 shown); Full-rolling guide devices are used at the entrances of K1 - K6. Double-row rolling guides are used for K1. High-speed steel rolls are used for the rolling mill of the K1 finished product pass for threaded rib anchor bolt steel bars. Tungsten carbide rolls are used for the rolling mill of the K2 flat elliptical pass with a grooved bottom convexity. High-boron steel rolls are used for the rolling mill of the K3 symmetric flat box splitting pass. High-boron steel rolls are used for the rolling mill of the K4 symmetric flat box pre-splitting pass, providing technical guarantees for the surface quality and dimensional stability of the finished product, and realizing the stable production of ribbed anchor bolts by adopting the splitting rolling process technology. In particular, high-speed steel is selected for K1. The transverse ribs of the steel bars for continuous equal-height threaded rib anchor bolts are characterized by being high and thick. Since the tungsten carbide material and high-boron steel material are prone to chipping and block falling during roll turning and rib washing, there are processing defects. The high-speed steel roll of K1 has a moderate hardness and is easy to process; the roll phase connecting shaft of the K1 finished product pass for threaded rib anchor bolt steel bars adopts a crankshaft-type connecting shaft. The functional design of this adjustable coupling realizes the relative rotation of the outer gear shaft sleeve at the roll end and the internal gear ring of the reducer under the condition that the two output shafts of the reducer that cooperate with the internal gear ring of the reducer do not rotate, thereby realizing the relative rotation of the phases of the threaded rib circular holes of the two rolls, so as to meet the requirements for the dimensional accuracy of the ribs; The parameters of the K3 pass are as follows: the pass height h = 18 mm, the pass width B = 50.19 mm, the roll gap S = 1.6 mm, the length of the bottom plane of the flat box pass groove is 12.12 mm, the splitting wedge angle is 56°, the splitting vertex radius R = 0.6 mm, and the outer fillet radius r = 2.5 mm; Between K3 and K2, and between K2 and K1, two splitting loopers are adopted to achieve tension-free rolling of the anchor rod splitting. The splitting line difference is controlled within no more than 0.3%, which can effectively solve the dimensional difference between the head, middle, and tail of the finished product, reduce the dimensional difference of the whole bar, and improve the dimensional accuracy of the product; the set height of the loop between K3 and K2 is 180 - 200 mm, and the loop adjustment delay is 200 - 400 ms; the set height of the loop between K2 and K1 is 190 - 220 mm, and the loop adjustment delay is 300 - 400 ms; the setting of the loop height is to achieve tension-free rolling, realize stable dimensions throughout the line, and small fluctuations in the dimensions of the whole bar; the principle of setting the loop adjustment delay is to perform loop adjustment after the mechanical limit is in place to prevent abnormal loop adjustment; the loops between K3 and K2 and between K2 and K1 are dedicated to specific use, and other stands are not allowed to use them. The purpose is to ensure the precise matching of the loop parameters and the material shape; After the multiple-length flying shear cutting, post-rolling controlled cooling is carried out. The temperature of entering the cooling bed is 820 °C. The selection basis of the temperature of entering the cooling bed is that during the cooling process of the steel on the cooling bed, neither abnormal microstructure appears, nor problems such as the reduction of the cooling bed life and the bending of the large cold shear cutting head due to too high steel temperature occur; During the splitting rolling process of the steel bar for continuously equal-height threaded rib anchor rods, two controlled coolings are carried out: the temperature after the first controlled cooling and tempering refers to the temperature at the entrance of the finishing mill. The main function of the first controlled cooling is to prevent the temperature from rising during the rolling process, which may cause the grains to become coarser and thus affect the mechanical properties; the temperature after the second controlled cooling and tempering refers to the temperature of entering the cooling bed. The function of the second controlled cooling is to perform post-rolling controlled cooling, inhibit the grain growth, and thus obtain the desired metallographic structure and mechanical properties.

[0028] The performance test results of the Φ18 mm steel bar for continuously equal-height threaded rib anchor rods are as follows: the yield strength is 385 MPa, the tensile strength is 555 MPa, the elongation after fracture is 30%, the metallographic structure is ferrite + pearlite, the impact energy at 20 °C is 85 J, and the out-of-roundness is 0.3 mm.

[0029] When adopting single-line production and the conventional oval-round pass system for the production process route, the daily output of a single line of Φ18 mm is 2,400 tons, and it can reach 4,000 tons after splitting rolling.

[0030] Example 2 A splitting rolling method for steel bars used in continuous equal-height threaded rib bolts, including billet heating, rough rolling, intermediate rolling, pre-finishing rolling, primary controlled cooling, finishing rolling, secondary controlled cooling, multiple-length flying shear cutting, cooling on the cooling bed, and natural aging, and finally preparing steel bars with a diameter of Φ20mm for continuous equal-height threaded rib bolts; Among them, when heating the billet, the furnace gas temperature in the soaking section of the heating furnace is controlled at 1080°C - 1130°C, and the heating time is ≥1 hour; After the billet is heated, it enters the rough rolling, intermediate rolling, pre-finishing rolling, and finishing rolling areas. The rolling start temperature is set at 985°C; the finishing rolling inlet temperature is 950°C. The roll pass system used in the finishing rolling stage is a splitting rolling pass system of K6 flat roll + K5 vertical box pass + K4 symmetric flat box pre-splitting pass + K3 symmetric flat box splitting pass + K2 flat ellipsoidal pass with a grooved bottom convexity + K1 finished product pass for threaded rib bolt steel bars (as Figures 1-6 shown); Full-rolling guide devices are used at the inlets of K1 - K6. Double-row rolling guides are used for K1. High-speed steel rolls are used for the rolling mill of the K1 finished product pass for threaded rib bolt steel bars. Tungsten carbide rolls are used for the rolling mill of the K2 flat ellipsoidal pass with a grooved bottom convexity. High-boron steel rolls are used for the rolling mill of the K3 symmetric flat box splitting pass. High-boron steel rolls are used for the rolling mill of the K4 symmetric flat box pre-splitting pass, providing technical guarantees for the surface quality and dimensional stability of the finished product, and realizing the stable production of ribbed bolts by adopting the splitting rolling process technology. In particular, high-speed steel is selected for K1. The transverse ribs of the steel bars used in continuous equal-height threaded rib bolts are characterized by being high and thick. Since tungsten carbide and high-boron steel are prone to chipping and block dropping during roll turning and rib washing, there are processing defects. The high-speed steel roll of K1 has a moderate hardness and is easy to process; the roll phase connecting shaft of the K1 finished product pass for threaded rib bolt steel bars adopts a crankshaft-type connecting shaft. The functional design of this adjustable coupling realizes the relative rotation of the outer gear shaft sleeve at the roll end and the internal gear ring of the reducer under the condition that the two output shafts of the reducer that match the internal gear ring in the control reducer do not rotate, thereby realizing the relative rotation of the phases of the threaded rib circular holes of the two rolls, and thus meeting the requirements for the dimensional accuracy of the ribs; The parameters of the K3 pass are: pass height h = 19.8mm, pass width B = 58.18mm, roll gap S = 1.9mm, the length of the flat box-shaped hole bottom plane is 11.67mm, the splitting wedge angle is 56°, the splitting apex radius R = 0.47mm, and the outer fillet radius r = 2.5mm; Between K3 and K2, and between K2 and K1, two split loopers are adopted, realizing the tension-free rolling of anchor bolts. The split line difference is controlled within no more than 0.3%, which can effectively solve the dimensional differences at the head, middle, and tail of the finished product, reduce the dimensional differences along the whole bar, and improve the dimensional accuracy of the product. The set height of the loop between K3 and K2 is 180 - 200 mm, and the loop adjustment delay is 200 - 400 ms. The set height of the loop between K2 and K1 is 190 - 220 mm, and the loop adjustment delay is 300 - 400 ms. The setting of the loop height is to achieve tension-free rolling, realizing stable dimensions throughout the line and small fluctuations in the dimensions along the whole bar. The principle for setting the loop adjustment delay is to perform loop adjustment after the mechanical limit is in place to prevent abnormal loop adjustment. The loops between K3 and K2 and between K2 and K1 are for dedicated use only, and other stands are not allowed to use them. The purpose is to ensure the precise matching of loop parameters and the stock shape. After the multiple-length flying shear cuts, post-rolling controlled cooling is carried out. The temperature for entering the cooling bed is 820 °C. The selection of the temperature for entering the cooling bed is based on the fact that during the cooling process on the cooling bed, neither abnormal microstructure appears in the steel nor problems such as reduced cooling bed life and large cold shear shear bends due to too high steel temperature occur. During the split rolling process of steel bars for continuously equal-height threaded rib anchor bolts, two-stage controlled cooling is carried out. The temperature after the first-stage controlled cooling and tempering refers to the entry temperature of the finishing mill. The main function of the first-stage controlled cooling is to prevent the temperature from rising during the rolling process, which may cause the grains to become coarser and thus affect the mechanical properties. The temperature after the second-stage controlled cooling and tempering refers to the temperature for entering the cooling bed. The function of the second-stage controlled cooling is to perform post-rolling controlled cooling to inhibit grain growth, thereby obtaining the desired metallographic structure and mechanical properties.

[0031] The performance test results of the steel bars for Φ20 mm continuously equal-height threaded rib anchor bolts are as follows: yield strength is 400 MPa, tensile strength is 560 MPa, elongation after fracture is 29%, metallographic structure is ferrite + pearlite, impact energy at 20 °C is 90 J, and out-of-roundness is 0.3 mm.

[0032] When adopting single-line production and the production process route uses the conventional oval-round pass system, the daily output of a single line for Φ20 mm is 2,800 tons, and it can reach 4,000 tons after split rolling.

[0033] Example 3 A split rolling method for steel bars for continuously equal-height threaded rib anchor bolts includes billet heating, rough rolling, medium rolling, pre-finishing rolling, first-stage controlled cooling, finishing rolling, second-stage controlled cooling, multiple-length flying shear cutting, cooling on the cooling bed, and natural aging, and finally prepares steel bars for Φ18 mm continuously equal-height threaded rib anchor bolts. Among them, during billet heating, the furnace gas temperature in the soaking section of the heating furnace is controlled at 1,080 °C - 1,130 °C, and the heating time is ≥ 1 hour. After the billet is heated, it enters the rough rolling, medium rolling, pre-finishing rolling and finishing rolling areas. The starting rolling temperature is set at 985 °C; the entry temperature of the finishing rolling is 930 °C. The roll pass system used in the finishing rolling stage is a split rolling pass system of K6 flat roll + K5 vertical box pass + K4 symmetrical flat box pre-split pass + K3 symmetrical flat box split pass + K2 flat ellipsoidal pass with groove bottom convexity + K1 finished product pass for ribbed anchor bar steel bars (as Figures 1-6 shown); Full-rolling guide devices are used at the inlets of K1-K6. Double-row rolling guides are used for K1. High-speed steel rolls are used for the rolling mill of the K1 finished product pass for ribbed anchor bar steel bars. Tungsten carbide rolls are used for the rolling mill of the K2 flat ellipsoidal pass with groove bottom convexity. High-boron steel rolls are used for the rolling mill of the K3 symmetrical flat box split pass. High-boron steel rolls are used for the rolling mill of the K4 symmetrical flat box pre-split pass, providing technical guarantee for the surface quality and dimensional qualification of the finished product, and realizing the stable production of ribbed anchor bars by adopting the split rolling process technology. In particular, high-speed steel is selected for K1. The transverse ribs of the steel bars for continuous equal-height ribbed anchor bars are characterized by being high and thick. Since the tungsten carbide material and high-boron steel material are prone to chipping and block falling during roll turning and rib washing, there are processing defects. The high-speed steel roll of K1 has a moderate hardness and is easy to process; the roll phase connecting shaft of the K1 finished product pass for ribbed anchor bar steel bars adopts a crankshaft-type connecting shaft. The functional design of this adjustable coupling realizes the relative rotation of the outer gear shaft sleeve at the roll end and the internal gear ring of the reducer under the condition that the two output shafts of the reducer that are matched with the internal gear ring in the reducer do not rotate, so as to realize the relative rotation of the phases of the circular holes of the ribbed threads of the two rolls, thus meeting the requirements for the dimensional accuracy of the ribs; The parameters of the K3 pass are: pass height h = 18 mm, pass width B = 50.19 mm, roll gap S = 1.6 mm, the length of the bottom plane of the flat box pass groove is 12.12 mm, the split wedge angle is 56°, the split vertex radius R = 0.6 mm, and the outer fillet radius r = 2.5 mm; Two-split loopers are used between K3-K2 and between K2-K1, realizing the tension-free rolling of the anchor bar split. The split line difference is controlled to be no more than 0.3%, which can effectively solve the dimensional difference between the head, middle and tail of the finished product, reduce the dimensional difference of the whole bar, and improve the dimensional accuracy of the product; the set height of the looper between K3-K2 is 180 - 200 mm, and the looper adjustment delay is 200 - 400 ms; the set height of the looper between K2-K1 is 190 - 220 mm, and the looper adjustment delay is 300 - 400 ms; the setting of the looper height is to achieve tension-free rolling, realize stable dimensions throughout the line and small fluctuations in the dimensions of the whole bar; the principle of setting the looper adjustment delay is to adjust the looper after the mechanical limit is in place to prevent abnormal adjustment of the looper; the loopers between K3-K2 and between K2-K1 are dedicated to specific use, and other stands are not allowed to use them, aiming to ensure the precise matching of the looper parameters and the stock shape; After the multiple-length flying shear cutting, post-rolling controlled cooling is carried out. The temperature on the cooling bed is 810°C. The selection basis of the temperature on the cooling bed is that during the cooling process on the cooling bed, neither abnormal microstructure appears in the steel, nor problems such as the reduction of the cooling bed life and the bending of the large cold shear cutting head occur due to too high steel temperature. During the split rolling process of the steel bar for continuous equal-height threaded rib anchor bolts, two controlled coolings are carried out: one controlled cooling after tempering refers to the temperature at the entrance of finish rolling. The main function of one controlled cooling is to prevent the temperature from rising during the rolling process, thus causing the grains to become coarser and further affecting the mechanical properties; the temperature after the second controlled cooling and tempering refers to the temperature on the cooling bed. The function of the second controlled cooling is to carry out post-rolling controlled cooling and inhibit the grain growth, so as to obtain the desired metallographic structure and mechanical properties.

[0034] The performance test results of the Φ18mm steel bar for continuous equal-height threaded rib anchor bolts are as follows: the yield strength is 380MPa, the tensile strength is 549MPa, the elongation after fracture is 29%, the metallographic structure is ferrite + pearlite, the impact energy at 20°C is 82J, and the out-of-roundness is 0.3mm.

[0035] Example 4 A split rolling method for the steel bar for continuous equal-height threaded rib anchor bolts, including billet heating, rough rolling, medium rolling, pre-finish rolling, primary controlled cooling, finish rolling, secondary controlled cooling, multiple-length flying shear cutting, cooling on the cooling bed and natural aging, and finally preparing the Φ18mm steel bar for continuous equal-height threaded rib anchor bolts; Among them, when heating the billet, the furnace gas temperature in the soaking section of the heating furnace is controlled at 1080°C - 1130°C, and the heating time ≥ 1 hour; After the billet is heated, it enters the rough rolling, medium rolling, pre-finish rolling and finish rolling areas. The starting rolling temperature is set at 985°C; the temperature at the entrance of finish rolling is 950°C. The roll pass system used in the finish rolling stage is the split rolling pass system of K6 flat roll + K5 vertical box pass + K4 symmetric flat box pre-split pass + K3 symmetric flat box split pass + K2 flat ellipsoidal pass with groove bottom convexity + K1 finished product pass for threaded rib anchor bolt steel bar (as Figures 1-6 shown); The K1-K6 inlets adopt full-rolling guide devices. K1 uses double-row rolling guides. The rolling mill for the finished product hole of K1 threaded rib anchor bar steel bars uses high-speed steel rolls. The rolling mill for the K2 flat elliptical hole with a grooved bottom convexity uses tungsten carbide rolls. The rolling mill for the K3 symmetric flat box split hole uses high-boron steel rolls. The rolling mill for the K4 symmetric flat box pre-split hole uses high-boron steel rolls. This provides technical guarantees for the surface quality and dimensional stability of the finished products, and realizes the stable production of ribbed anchor bars by adopting the split rolling process technology. In particular, K1 selects high-speed steel. The transverse ribs of the steel bars for continuous equal-height threaded rib anchor bars are characterized by being high and thick. Since tungsten carbide and high-boron steel are prone to chipping and block falling during roll turning and rib washing, there are processing defects. The high-speed steel rolls of K1 have a moderate hardness and are easy to process. The roll phase connecting shaft of the finished product hole of K1 threaded rib anchor bar steel bars adopts a crankshaft-type connecting shaft. The functional design of this adjustable coupling realizes the relative rotation of the external gear shaft sleeve at the roll end and the internal gear ring of the reducer under the condition that the two output shafts of the reducer that cooperate with the internal gear ring in the reducer do not rotate, thereby realizing the relative rotation of the phases of the threaded rib circular holes of the two rolls, so as to meet the requirements for the dimensional accuracy of the ribs; The parameters of the K3 pass are: pass height h = 18 mm, pass width B = 50.19 mm, roll gap S = 1.6 mm, the length of the bottom plane of the flat box pass groove is 12.12 mm, the split wedge angle is 56°, the split apex radius R = 0.6 mm, and the external fillet radius r = 2.5 mm; Two-split loopers are adopted between K3 and K2, and between K2 and K1, realizing the tension-free rolling of the anchor bar split. The split line difference is controlled to be no more than 0.3%, which can effectively solve the dimensional difference of the head, middle and tail of the finished product, reduce the dimensional difference of the whole bar, and improve the dimensional accuracy of the product. The set height of the looper between K3 and K2 is 180 - 200 mm, and the looper adjustment delay is 200 - 400 ms. The set height of the looper between K2 and K1 is 190 - 220 mm, and the looper adjustment delay is 300 - 400 ms. The setting of the looper height is to achieve tension-free rolling, realize stable dimensions throughout the line, and small fluctuations in the dimensions of the whole bar. The principle for setting the looper adjustment delay is to perform looper adjustment after the mechanical limit is in place to prevent abnormal adjustment of the looper. The loopers between K3 and K2 and between K2 and K1 are for dedicated use only, and other stands are not allowed to use them. The purpose is to ensure the accurate matching of the looper parameters and the stock shape; After the multiple-length flying shear cuts, post-rolling controlled cooling is carried out. The temperature for entering the cooling bed is 830 °C. The selection basis for the temperature for entering the cooling bed is that during the cooling process of the steel on the cooling bed, neither abnormal structures will appear, nor will problems such as reduced cooling bed life and large cold shear shear bends occur due to too high steel temperature; During the split rolling process of the steel bar for continuously equal-height threaded rib bolts, controlled cooling is carried out twice: the temperature after the first controlled cooling and tempering refers to the entry temperature of the finish rolling, and the main function of the first controlled cooling is to prevent the temperature from rising during the rolling process, which may cause the grains to become coarser and thus affect the mechanical properties; the temperature after the second controlled cooling and tempering refers to the temperature of entering the cooling bed, and the function of the second controlled cooling is to carry out controlled cooling after rolling to inhibit grain growth, so as to obtain the desired metallographic structure and mechanical properties.

[0036] The performance test results of the Φ18mm steel bar for continuously equal-height threaded rib bolts are as follows: the yield strength is 378MPa, the tensile strength is 548MPa, the elongation after fracture is 28%, the metallographic structure is ferrite + pearlite, the impact energy at 20°C is 81J, and the out-of-roundness is 0.3mm.

[0037] Comparative Example 1 A split rolling method for the steel bar for continuously equal-height threaded rib bolts, including billet heating, rough rolling, medium rolling, pre-finish rolling, the first controlled cooling, finish rolling, the second controlled cooling, double-length flying shear cutting, cooling on the cooling bed and natural aging, and finally preparing the Φ18mm steel bar for continuously equal-height threaded rib bolts; Among them, when heating the billet, the furnace gas temperature in the soaking section of the heating furnace is controlled at 1080°C - 1130°C, and the heating time is ≥1 hour; After the billet is heated, it enters the rough rolling, medium rolling, pre-finish rolling and finish rolling areas, and the rolling start temperature is set at 985°C; the entry temperature of the finish rolling is 950°C, and the roll pass system adopted in the finish rolling stage is the split rolling pass system of K6 flat roll + K5 vertical box pass + K4 symmetric flat box pre-splitting pass + K3 symmetric flat box splitting pass + K2 flat ellipsoidal pass with groove bottom convexity + K1 finished product pass for threaded rib bolt steel bar (as Figures 1-6 shown); The K1-K6 inlets adopt full-rolling guide devices. K1 uses a double-row rolling guide. The rolling mill for the finished product hole of the K1 threaded rib anchor rod steel bar uses a high-speed steel roll. The rolling mill for the K2 flat elliptical hole with a grooved bottom convexity uses a tungsten carbide roll. The rolling mill for the K3 symmetric flat box split hole uses a high-boron steel roll. The rolling mill for the K4 symmetric flat box pre-split hole uses a high-boron steel roll. This provides technical guarantee for the surface quality and dimensional stability of the finished product, and realizes the stable production of the ribbed anchor rod by adopting the split rolling process technology. In particular, K1 selects high-speed steel. The transverse ribs of the steel bar for continuous equal-height threaded rib anchor rods are characterized by being high and thick. Since tungsten carbide and high-boron steel are prone to chipping and block dropping during roll turning and rib washing, there are processing defects. The high-speed steel roll of K1 has a moderate hardness and is easy to process. The roll phase connecting shaft of the finished product hole of the K1 threaded rib anchor rod steel bar adopts a crankshaft-type connecting shaft. The functional design of this adjustable coupling realizes the relative rotation of the outer gear shaft sleeve at the roll end and the internal gear ring of the reducer under the condition that the two output shafts of the reducer that cooperate with the internal gear ring in the control reducer do not rotate, so as to realize the relative rotation of the phases of the threaded rib circular holes of the two rolls, thus meeting the requirements for the dimensional accuracy of the ribs. The parameters of the K3 pass are: pass height h = 18 mm, pass width B = 50.19 mm, roll gap S = 1.6 mm, the length of the flat box pass groove bottom plane is 12.12 mm, the split wedge angle is 56°, the split vertex radius R = 0.6 mm, and the outer fillet radius r = 2.5 mm. Two split loopers are used between K3 and K2, and between K2 and K1, realizing the tension-free rolling of the anchor rod split. The split line difference is controlled to be no more than 0.3%, which can effectively solve the dimensional difference between the head, middle, and tail of the finished product, reduce the dimensional difference of the whole bar, and improve the dimensional accuracy of the product. The set height of the looper between K3 and K2 is 180 - 200 mm, and the looper adjustment delay is 200 - 400 ms. The set height of the looper between K2 and K1 is 190 - 220 mm, and the looper adjustment delay is 300 - 400 ms. The setting of the looper height is to achieve tension-free rolling, realize stable dimensions throughout the line, and small fluctuations in the dimensions of the whole bar. The principle for setting the looper adjustment delay is to perform looper adjustment after the mechanical limit is in place to prevent abnormal adjustment of the looper. The loopers between K3 and K2 and between K2 and K1 are dedicated to specific uses, and other stands are not allowed to use them. The purpose is to ensure the precise matching of the looper parameters and the stock shape. After the multiple-length flying shear cuts, post-rolling controlled cooling is carried out, and the temperature on the cooling bed is 840 °C.

[0038] Red rust appears on the surface of the Φ18 mm steel bar for continuous equal-height threaded rib anchor rods prepared, affecting the product quality. The results of its performance testing are: yield strength is 355 MPa, tensile strength is 505 MPa, elongation after fracture is 22%, metallographic structure is ferrite + pearlite, impact energy at 20 °C is 50 J, and out-of-roundness is 0.3 mm.

[0039] Comparative Example 2 A split rolling method for steel bars used in continuous equal-height threaded rib anchor bolts, including billet heating, rough rolling, medium rolling, pre-finishing rolling, primary controlled cooling, finishing rolling, secondary controlled cooling, multiple-length flying shear cutting, cooling on the cooling bed, and natural aging, and finally preparing steel bars with a diameter of Φ18mm for continuous equal-height threaded rib anchor bolts; Among them, when heating the billet, the furnace gas temperature in the soaking section of the heating furnace is controlled at 1080°C - 1130°C, and the heating time is ≥1 hour; After the billet is heated, it enters the rough rolling, medium rolling, pre-finishing rolling, and finishing rolling areas, and the starting rolling temperature is set at 985°C; the entrance temperature of the finishing rolling is 950°C, and the roll pass system used in the finishing rolling stage is a split rolling pass system of K6 flat roll + K5 vertical box pass + K4 symmetric flat box pre-splitting pass + K3 symmetric flat box splitting pass + K2 flat ellipse pass with a grooved bottom convexity + K1 finished product pass for threaded rib anchor bolt steel bars (as Figures 1-6 shown); Full-rolling guide devices are used at the entrances of K1 - K6. Double-row rolling guides are used for K1. High-speed steel rolls are used for the rolling mill of the K1 finished product pass for threaded rib anchor bolt steel bars. Tungsten carbide rolls are used for the rolling mill of the K2 flat ellipse pass with a grooved bottom convexity. High-boron steel rolls are used for the rolling mill of the K3 symmetric flat box splitting pass. High-boron steel rolls are used for the rolling mill of the K4 symmetric flat box pre-splitting pass, providing technical guarantees for the surface quality and dimensional stability of the finished product, and realizing the stable production of ribbed anchor bolts by adopting the split rolling process technology. In particular, high-speed steel is selected for K1. The transverse ribs of the steel bars for continuous equal-height threaded rib anchor bolts are characterized by being high and thick. Since tungsten carbide and high-boron steel are prone to chipping and block falling during roll turning and rib washing, there are processing defects. The high-speed steel roll of K1 has a moderate hardness and is easy to process; the roll phase connecting shaft of the K1 finished product pass for threaded rib anchor bolt steel bars adopts a crankshaft-type connecting shaft. The functional design of this adjustable coupling realizes the relative rotation of the outer gear shaft sleeve at the roll end and the internal gear ring of the reducer under the condition that the two output shafts of the reducer that cooperate with the internal gear ring in the control reducer do not rotate, thereby realizing the relative rotation of the phases of the threaded rib circular holes of the two rolls, so as to meet the requirements for the dimensional accuracy of the ribs; The parameters of the K3 pass are: pass height h = 18mm, pass width B = 50.19mm, roll gap S = 1.6mm, the length of the bottom plane of the flat box-shaped pass groove is 12.12mm, the splitting wedge angle is 56°, the splitting apex radius R = 0.6mm, and the outer fillet radius r = 2.5mm; Between K3 and K2, and between K2 and K1, two split loopers are adopted to achieve the tension-free rolling of anchor bolts. The split line difference is controlled within no more than 0.3%, which can effectively solve the dimensional difference of the head, middle and tail of the finished product, reduce the dimensional difference of the whole bar, and improve the dimensional accuracy of the product. The set height of the loop between K3 and K2 is 180 - 200 mm, and the loop adjustment delay is 200 - 400 ms. The set height of the loop between K2 and K1 is 190 - 220 mm, and the loop adjustment delay is 300 - 400 ms. The setting of the loop height is to achieve tension-free rolling, realize stable dimensions throughout the line, and small fluctuations in the dimensions of the whole bar. The principle of setting the loop adjustment delay is to perform loop adjustment after the mechanical limit is in place to prevent abnormal loop adjustment. The loops between K3 and K2 and between K2 and K1 are for dedicated use only, and other stands are not allowed to use them. The purpose is to ensure the precise matching of loop parameters and the shape of the material. After the multiple-length flying shear cuts, post-rolling controlled cooling is carried out, and the temperature on the cooling bed is 780 °C.

[0040] The surface of the Φ18 mm continuously equal-height ribbed anchor bolt steel bar prepared has tempered martensite structure, which does not meet the industry standard for hot-rolled ribbed steel bars for anchor bolts (YB / T 4364-2014). The results of its performance tests are as follows: yield strength is 450 MPa, tensile strength is 590 MPa, elongation after fracture is 16%, metallographic structure is ferrite + pearlite + tempered martensite, impact energy at 20 °C is 30 J, and out-of-roundness is 0.3 mm.

[0041] Although the present invention has been described in detail by referring to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions should all be within the scope of the present invention. / Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered by the protection scope of the present invention.

Claims

1. A method for cutting and rolling steel bars for continuous equal-height threaded rib anchor rods, characterized in that: After heating, the billet enters the rough rolling, intermediate rolling, pre-finishing and finishing rolling areas. The slitting rolling hole system used in the finishing rolling area is K6 flat roller + K5 vertical box hole + K4 symmetrical flat box pre-slitting hole + K3 symmetrical flat box cutting hole + K2 flat elliptical hole with groove bottom convexity + K1 threaded rib anchor bar finished hole; K1~K6 entrances use full rolling guide devices, and K1 uses double-row rolling guides; two slitting loopers are used between K3~K2 and between K2~K1, and the slitting line difference is controlled to be no more than 0.3%; During the slitting rolling process, controlled cooling is performed twice: the temperature after the first controlled cooling and tempering refers to the finishing rolling entrance temperature, and the temperature range of the finishing rolling entrance temperature is 930-950℃; the temperature after the second controlled cooling and tempering refers to the upper cooling bed temperature, and the temperature range of the upper cooling bed temperature is 810-830℃; The specifications of the prepared continuous equal-height threaded rib anchor steel bars include Φ18mm and Φ20mm.

2. A method for cutting and rolling steel bars for continuous equal-height threaded rib anchor rods as claimed in claim 1, characterized in that: When heating the steel billet, the furnace gas temperature in the soaking section of the heating furnace is controlled at 1080℃-1130℃, and the heating time is ≥1 hour.

3. A method for cutting and rolling steel bars for continuous equal-height threaded rib anchor rods as claimed in claim 1, characterized in that: The rolling temperature of the billet after heating is 960-1000℃.

4. A method for cutting and rolling steel bars for continuous equal-height threaded rib anchor rods as claimed in claim 1, characterized in that: In the finishing rolling area, the K1 mill for threaded rib anchor rod finished holes uses high-speed steel rolls, the K2 mill for flat elliptical holes with groove bottom convexity uses tungsten carbide rolls, the K3 mill for symmetrical flat box cutting holes uses high boron steel rolls, and the K4 mill for symmetrical flat box pre-cut holes uses high boron steel rolls.

5. A method for cutting and rolling steel bars for continuous equal-height threaded rib anchor rods as claimed in claim 1, characterized in that: The roller phase connecting shaft of the K1 threaded rib anchor bar finished hole adopts a crankshaft connecting shaft.

6. A method for cutting and rolling steel bars for continuous equal-height threaded rib anchor rods as claimed in claim 1, characterized in that: When preparing steel bars for continuous equal-height threaded rib anchor rods with a specification of Φ18mm, the parameters of the K3 symmetrical flat box cutting hole are: hole height h=18mm, hole width B=50.19mm, roller gap S=1.6mm, flat box hole bottom plane length of 12.12mm, cutting wedge angle of 56°, cutting top angle radius R=0.6mm, outer round angle radius r=2.5mm.

7. A method for cutting and rolling steel bars for continuous equal-height threaded rib anchor rods as claimed in claim 1, characterized in that: When preparing steel bars for continuous equal-height threaded rib anchor rods with a specification of Φ20mm, the parameters of the K3 symmetrical flat box cutting hole are: hole height h=19.8mm, hole width B=58.18mm, roller gap S=1.9mm, flat box hole bottom plane length of 11.67mm, cutting wedge angle of 56°, cutting top angle radius R=0.47mm, outer round corner radius r=2.5mm.

8. A method for cutting and rolling steel bars for continuous equal-height threaded rib anchor rods as claimed in claim 1, characterized in that: The setting height of the two cutting loopers between K3 and K2 is 180-200mm, and the loop adjustment delay is 200-400ms; the setting height of the two cutting loopers between K2 and K1 is 190-220mm, and the loop adjustment delay is 300-400ms; the loopers between K3 and K2 and the loopers between K2 and K1 are special-purpose.

9. A method for cutting and rolling steel bars for continuous equal-height threaded rib anchor rods as claimed in claim 1, characterized in that: Double-length flying shearing is carried out between finishing rolling and cooling on the cooling bed.

10. A method for cutting and rolling steel bars for continuous equal-height threaded rib anchor rods as claimed in claim 1, characterized in that: After cooling on the cooling bed, natural aging is carried out.

Images