Four-segmentation production process for twisted steel with diameter phi of 16 mm
By adopting an optimized four-slicing process in the production of Φ16 mm threaded steel bars, the problems of high cost and high energy consumption in the prior art are solved, lower production costs and higher product quality consistency, and significant economic benefits are brought.
Patent Information
- Application Number
- CN202510502063.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-21
- Publication Date
- 2025-06-27
AI Technical Summary
In the prior art, the two-section or three-section process of Φ16 mm threaded steel bars has high cost and high energy consumption, and it is difficult to achieve low-cost production under low-temperature controlled rolling conditions.
An optimized four-sliced production process is adopted to reduce production costs and improve product accuracy and process stability by adjusting the opening rolling temperature, optimizing the hole-type system design and renovating the cooling nozzle of the controlled rolling tank.
It has achieved the reduction of production costs and energy consumption, improved the consistency of product yield strength, tensile strength and strong yield ratio, and achieved an annual profit and tax of more than 60 million yuan.
Smart Images
Figure CN120205590A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of iron and steel metallurgy, and particularly relates to a four-split production process for Φ16 mm ribbed steel bars. Background Art
[0002] The split rolling technology, due to its unique "replacing rolling with splitting" process characteristics, shows significant advantages in many aspects. From the dimensions of energy consumption, equipment investment, and production efficiency, this technology performs particularly outstandingly. In actual production operations, for each additional split line number, the configuration of two rolling mills can be reduced. At the same time, the rolling power consumption can be reduced by more than 10%, and the consumption of other various resources will also show a significant decrease accordingly. Based on these advantages, the split rolling technology has become the core development trend in the production field of small-sized bar and wire products and has attracted much attention in the relevant industries at home and abroad. In the current production practice of bars such as ribbed steel bars, the application of split rolling technology in specific specification products has become relatively mature. For example, for products with a Φ12 mm specification, a four-split or five-split process is generally adopted; for products with a Φ14 mm specification, a three-split or four-split process is mostly used; and for products with a Φ16 mm specification, a two-split or three-split process is mainly applied. However, in comparison, there are relatively obvious short boards in the development process of the four-split process for the Φ16 mm specification. Especially under the condition of low-temperature controlled rolling, the low-cost production technology has not yet achieved a substantial breakthrough. This is because the four-split process requires precise control of four rolling lines simultaneously, and its technical complexity has increased significantly compared with two-split and three-split. Specifically, the design of the pass system needs to meet the requirements of multiple metal splits, which greatly increases the difficulty of coordinating the deformation of the rolled piece; during the multi-line rolling process, the control requirements for temperature uniformity are more stringent; the difficulty of adjusting the tension balance between each split line has also increased significantly. In addition, this process puts forward more stringent requirements for the precision maintenance of rolling rolls and guide devices, the finished product size tolerance, and quality control and other links. Under the existing technical conditions, the production of Φ16 mm specification bars still mainly uses a two-split or three-split process. Due to the above technical problems, the four-split process has not been able to achieve stable application, which also leaves a large room for optimization in terms of production cost and energy consumption. Therefore, developing a four-split production process suitable for Φ16 mm specification bars is of great practical significance for improving the overall production technology level of bars such as ribbed steel bars. Summary of the Invention
[0003] Aiming at the technical problems of high cost and high energy consumption in the two-split or three-split process for Φ16 mm ribbed steel bars in the prior art, the present invention provides a four-split production process for Φ16 mm ribbed steel bars, with good quality control and lower cost compared with the conventional three-split process for Φ16 mm specification bars.
[0004] The technical solution of the present invention is as follows: The present invention provides a four-split production process for Φ16 mm ribbed steel bars. After batching, the billets are heated, rolled, controlled rolling and controlled cooling are carried out in sequence, and finally the four-split Φ16 mm ribbed steel bars are obtained after finishing and collecting. When heating the billets, the starting rolling temperature is 920 - 960 °C. When rolling, a split rolling pass system of K7 flat roll + K6 flat roll + K5 vertical box pass + K4 symmetric round hole pre-splitting pass + K3 symmetric round hole splitting pass + K2 single arc ellipse pass + K1 finished product pass and a stock shape system are adopted. The K4 symmetric round hole pre-splitting pass is a round hole type with the central line area 2% - 3% smaller than the side line area. The height of the pass is 20.7 mm, the width of the pass is 88 mm, and the width of the notch at both side lines is 21.5 mm, and the width of the notch at the middle two lines is 22.5 mm. When carrying out controlled rolling and controlled cooling, a controlled rolling water tank cooling nozzle with an internal water passage is used. The internal water passage introduces cooling water into the second cavity part of the nozzle. The top and bottom surfaces of the middle replacement core of the controlled rolling water tank cooling nozzle are designed as a flared + straight section water spraying slit, and the size of the middle replacement core is 35.5×96 mm.
[0005] Furthermore, for batching, by mass percentage, the chemical composition components include C 0.22% - 0.25%, Si 0.55% - 0.75%, Mn 1.40% - 1.60%, P ≤ 0.045%, S ≤ 0.045%, and the rest are Fe and inevitable impurities.
[0006] Furthermore, when heating the billets, the furnace gas temperature in the first heating section: the left top temperature is 750 - 850 °C, the right top temperature is 750 - 850 °C, the left side wall temperature is 750 - 850 °C, and the right side wall temperature is 750 - 850 °C; the furnace gas temperature in the third heating section: the left top temperature is 860 - 940 °C, the right top temperature is 860 - 940 °C, the left side wall temperature is 930 - 1010 °C, and the right side wall temperature is 930 - 1010 °C; the furnace gas temperature in the soaking section: the left top temperature is 920 - 1000 °C, the right top temperature is 920 - 1000 °C, the left side wall temperature is 940 - 1020 °C, and the right side wall temperature is 940 - 1020 °C.
[0007] Furthermore, the stock shape height of the K7 flat roll is 32.5 mm ± 1 mm, and the stock shape width is 92.8 mm ± 1 mm; the stock shape height of the K6 flat roll is 24 mm ± 1 mm, and the stock shape width is 95 mm ± 1 mm.
[0008] Furthermore, the bottom width of the groove of the K5 vertical box hole is 20.5 mm, the width of the groove opening is 26.5 mm, the fillet is R3.5 mm, the height of the hole shape is 80 mm, and the rolling load is ≥12%; the elongation coefficient of the K3 symmetric round hole splitting hole is 1.10 - 1.25, the thickness of the splitting zone is 1.4 mm, the area of the middle line of the K3 symmetric round hole splitting hole is 2% smaller than the area of the side line, the middle two lines are both 18.97 mm, the two side lines are both 19.04 mm, the total width is 89.5 mm, and the width of each line is 22.25 mm.
[0009] Furthermore, the height of the stock shape of the K2 single - arc elliptical hole is 12.8 mm ± 1 mm, and the width of the stock shape is 29.37 mm ± 1 mm; the height of the stock shape of the K1 finishing hole is 15.1 mm ± 1 mm, and the width of the stock shape is 15.01 mm ± 1 mm.
[0010] Furthermore, all of K1 - K7 use imported rolling guide guard structures, which improves the stability of the stock shape during the production process and reduces or avoids quality problems such as product size fluctuations caused by unstable stock deviation.
[0011] Furthermore, during controlled rolling and controlled cooling, a 29.5×97 mm water - passing pipe is used, and the controlled rolling temperature is 850 - 900°C.
[0012] Furthermore, the width of the water - spraying slot in the straight - line section of the cooling nozzle of the controlled - rolling water tank is 2 mm, and the opening angle is 60°.
[0013] Furthermore, the inner - hole size of the imported plug - in part in the cooling nozzle of the controlled - rolling water tank is 29.5×96.0 mm.
[0014] The beneficial effects of the present invention are as follows: The present invention provides a four - splitting production process for Φ16 mm ribbed steel bars. By optimizing the temperature control, pass - system design, and transformation of the cooling nozzle of the controlled - rolling water tank in the four - splitting production process, it improves product precision and process stability while reducing production costs. Specifically, the starting rolling temperature is reduced to the range of 920 - 960°C. Compared with the starting rolling temperature of 965 - 1000°C in the traditional three - splitting process, it reduces the fuel consumption of the heating furnace and the burning loss of alloying elements. Practical applications show that after adopting this four - splitting production process, the power consumption per ton of steel is reduced by 6.5 kWh, the coal consumption is reduced by 5 kg, the comprehensive production cost is reduced by 9.6 yuan per ton, the hourly output is increased by 54.2 tons per hour, and the annual profit and tax benefit exceeds 60 million yuan.
[0015] By adopting the split rolling pass and stock shape system of K7 flat roll + K6 flat roll + K5 vertical box pass + K4 symmetric round pre-split pass + K3 symmetric round split pass + K2 single-arc ellipse pass + K1 finished product pass, especially designing the parameters of the K4 symmetric round pre-split pass, the central line area is designed to be 2% - 3% smaller than the side line, and combined with the differential design of increasing the width of the middle wire groove by 1 mm, it effectively compensates for the difference in metal flow caused by the temperature gradient during rolling, making the elongation coefficients of the four-line rolled pieces tend to be consistent. Through mechanical property tests, the yield strength of the Φ16 mm ribbed steel bars prepared by the present invention is stably maintained at 430 - 455 MPa, the tensile strength is controlled at 610 - 630 MPa, and the strength ratio is maintained at 1.39 - 1.42. Compared with the Φ16 mm ribbed steel bars obtained by the original three-split process, which have problems of discrete mechanical properties, the present invention significantly improves the within-batch consistency.
[0016] Moreover, the present invention modifies the intermediate replacement core structure of the controlled rolling water tank cooling nozzle, changing the original air dispersion holes into a water spraying slit combined with a flared mouth and a straight section. On the premise of keeping the appearance size of the nozzle unchanged, the cooling uniformity of the intermediate core part is improved by optimizing the water flow path. Combined with the suspended arrangement of the rolled piece at the nozzle position, the synchronous improvement of the surface quality and mechanical properties of the four-line rolled piece is realized. Through the collaborative innovation of multiple links, a set of economical and reliable production solutions is provided for the four-split production of Φ16 mm ribbed steel bars. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] 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 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.
[0018] Figure 1 It is the roll pass drawing of the K7 flat roll used in the rolling step of the present invention.
[0019] Figure 2 It is the roll pass drawing of the K6 flat roll used in the rolling step of the present invention.
[0020] Figure 3 It is the roll pass drawing of the K5 vertical box pass used in the rolling step of the present invention.
[0021] Figure 4 It is the roll pass drawing of the K4 symmetric round pre-split pass used in the rolling step of the present invention.
[0022] Figure 5 It is the roll pass drawing of the K3 symmetric round split pass used in the rolling step of the present invention.
[0023] Figure 6 It is the roll pass drawing of the K2 single-arc ellipse hole used in the rolling step of the present invention.
[0024] Figure 7 It is the roll pass drawing of the K1 finished product hole used in the rolling step of the present invention.
[0025] Figure 8 It is the schematic diagram before the transformation of the cooling nozzles of the controlled rolling water tank of the present invention.
[0026] Figure 9 It is the schematic diagram after the transformation of the cooling nozzles of the controlled rolling water tank of the present invention.
[0027] Figure 10 It is the front schematic diagram before the transformation of the intermediate replacement core of the cooling nozzles of the controlled rolling water tank of the present invention.
[0028] Figure 11 It is the front schematic diagram after the transformation of the intermediate replacement core of the cooling nozzles of the controlled rolling water tank of the present invention.
[0029] Figure 12 It is the side schematic diagram before the transformation of the intermediate replacement core of the cooling nozzles of the controlled rolling water tank of the present invention.
[0030] Figure 13 It is the side schematic diagram after the transformation of the intermediate replacement core of the cooling nozzles of the controlled rolling water tank of the present invention.
[0031] Figure 14 It is the metallographic structure photo of the Φ16 mm ribbed steel bar in Example 1 of the present invention.
[0032] Figure 15 It is the metallographic structure photo of the Φ16 mm ribbed steel bar in Example 2 of the present invention. Detailed implementation manners
[0033] In order 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 with reference to 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 of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the scope of protection of the present invention.
[0034] Example 1 A four-split production process for Φ16 mm ribbed steel bars, in which the chemical component groups obtained by batch mixing are successively subjected to billet heating, rolling, controlled rolling and controlled cooling, and finishing and collection to obtain Φ16 mm ribbed steel bars; Specifically, it includes the following steps: Step 1: Batch preparation. By mass percentage, the chemical composition components include 0.22% C, 0.75% Si, 1.40% Mn, 0.045% P, 0.045% S, and the rest is Fe and inevitable impurities; Step 2: Billet heating. The rolling start temperature is 920°C. In the three-split production process of Φ16 mm ribbed steel bars, the rolling start temperature is usually in the range of 965 - 1000°C. When the rolling start temperature is reduced by more than 40°C, with the temperature decrease, the coal consumption and alloy cost will decrease accordingly; The furnace gas temperature in the first heating zone: the left top temperature is 750°C, the right top temperature is 750°C, the left side wall temperature is 750°C, and the right side wall temperature is 750°C; the furnace gas temperature in the third heating zone: the left top temperature is 940°C, the right top temperature is 940°C, the left side wall temperature is 1010°C, and the right side wall temperature is 1010°C; the furnace gas temperature in the soaking zone: the left top temperature is 920°C, the right top temperature is 920°C, the left side wall temperature is 1020°C, and the right side wall temperature is 1020°C; Step 3: Rolling. Adopt the split rolling pass and stock shape system of K7 flat roll + K6 flat roll + K5 vertical box pass + K4 symmetric round pre-split pass + K3 symmetric round split pass + K2 single-arc oval pass + K1 finish pass (as Figures 1 - 7 shown), and compile a rolling program table; Among them, for the K7 flat roll: From the perspective of improving production smoothness, the stock shape height is precisely controlled at 32.5 mm, and the stock shape width is 92.8 mm; For the K6 flat roll: To ensure the reduction amount of K5 and the stability of the stock shape, the stock shape height is 24 mm, and the stock shape width is 95 mm; For the K5 vertical box pass: To alleviate the overload and line difference problems of the 15th stand, the bottom width of the groove is designed to be 20.5 mm, the width of the groove opening is designed to be 26.5 mm, the fillet is designed to be R3.5 mm, and the height of the pass is designed to be 80 mm; To ensure that when the stock shape and the fullness of the transverse ribs of the subsequent stands are adjusted as required, it cannot be too small, the rolling load is above 12%, and usually controlled at 40% - 60%; For the K4 symmetric round pre-split pass: The pre-splitting is a key pass for split production, which directly affects the line difference and dimensions of the finished product. To ensure the fullness and wear amount of both sides, the K4 symmetric round pre-split pass is designed as a round hole type with the central line area 2% - 3% smaller than the side line area. The height of the K4 pass is 20.7 mm, the width of the pass is 88 mm, the width of the groove opening at both side lines is 21.5 mm, and the width of the middle two lines is 22.5 mm. Based on the controlled rolling temperature state where the temperature of the middle line is lower than that of the side lines, such a pass design is beneficial to the control of the negative tolerance uniformity of the four-line finished product; K3 Symmetric Round Hole Split Hole: Regularize the two-line stock shapes of the rolled piece to prepare the stock shape for splitting. The optimal range of the elongation coefficient for this pass is between 1.10 and 1.25. According to experience and the characteristics of the finished product dimensions, the thickness of the split zone of the K3 symmetric round hole split hole is designed to be 1.4 mm. If the split zone is too thick or too wide, it cannot be pressed in the K2 pass, resulting in early appearance of rolling marks in the finished pass. At the same time, the splitting wheel is overloaded, causing accidents such as burning of the bearing of the guide guard. If the split zone is too thin, the split zone will be directly rolled onto the surface of the K2 stock, resulting in folding in the finished pass; The K3 symmetric round hole split pass is designed as a round split pass with the central line area 2% smaller than the side line area. The middle two lines are both 18.97 mm, the two side lines are both 19.04 mm, the total width is 89.5 mm, and the width of each line is 22.25 mm; K2 Single-arc Elliptical Hole: To ensure the height of the transverse ribs of the finished product, it is designed as an elliptical pass with a pass height of 12.8 mm and a pass width of 29.37 mm; K1 Finished Pass: The pass height is 15.1 mm and the pass width is 15.01 mm; To ensure the stability of the stock shape during the production process and reduce or avoid quality problems such as product size fluctuations caused by unstable stock position, all of K1 - K7 use imported rolling guide guard structures; Step 4: Controlled Rolling and Controlled Cooling. Use a 29.5×97 mm water pipe. The controlled rolling temperature is 850°C; Optimize and transform the structure of the cooling nozzles of the controlled rolling water tank to reduce the yin-yang surface and non-uniformity of the rolled piece. Optimize and improve the condition parameters of the controlled rolling nozzles for three-splitting of Φ16 mm ribbed steel bars as follows: (1) Keep the appearance and assembly dimensions of the controlled rolling water tank cooling nozzles for three-splitting of Φ16 mm ribbed steel bars unchanged. When producing four-splitting of Φ16 mm ribbed steel bars, open the internal water path of the controlled rolling water tank cooling nozzles, and introduce cooling water into the second cavity part of the nozzles to prepare for spraying and cooling the intermediate replacement core; Before transformation, the schematic diagram of the controlled rolling water tank cooling nozzles for three-splitting of Φ16 mm ribbed steel bars is shown in Figure 8 After transformation, the schematic diagram of the controlled rolling water tank cooling nozzles for four-splitting of Φ16 mm ribbed steel bars is shown in Figure 9 ; (2) Transform the intermediate replacement core in the controlled rolling water tank cooling nozzles. The top and bottom air dispersion holes in the middle section of the intermediate replacement core for three-splitting of Φ16 mm ribbed steel bars are transformed into a flared + straight-line spraying slit with a spraying slit width of 2 mm and an opening angle of 60°. Canceling the top and bottom air dispersion holes in the middle section of the intermediate replacement core for three-splitting of Φ16 mm ribbed steel bars can ensure the spraying pressure. The size of the intermediate replacement core is 35.5×96 mm, ensuring that the rolled piece is suspended 3 mm above and below at this position to improve uniformity; Before transformation, the front view of the intermediate replacement core of the controlled rolling water tank cooling nozzles for three-splitting of Φ16 mm ribbed steel bars is shown in Figure 10; After the transformation, the front view of the middle replacement core of the controlled rolling water tank cooling nozzle for four-split Φ16 mm ribbed steel bars is shown in Figure 11 ; Before the transformation, the side view of the middle replacement core of the controlled rolling water tank cooling nozzle for three-split Φ16 mm ribbed steel bars is shown in Figure 12 ; After the transformation, the side view of the middle replacement core of the controlled rolling water tank cooling nozzle for four-split Φ16 mm ribbed steel bars is shown in Figure 13 ; (3) The size of the inlet plug in the controlled rolling water tank cooling nozzle is not adjusted, and the inner hole size is 29.5×96.0 mm, which is the same as that of the controlled rolling water tank cooling nozzle for three-split Φ16 mm ribbed steel bars; When Φ16 mm ribbed steel bars are three-split, the center line temperature is 60°C higher than the side line temperature. By optimizing and transforming the structure of the controlled rolling water tank cooling nozzle, the temperature difference between the center line and the side line is reduced, and the center line is only 30°C higher than the side line temperature; Step Five: After finishing and collecting by the conventional method, four-split Φ16 mm ribbed steel bars are obtained, and their metallographic structure meets the national standard requirements. The metallographic structure diagram is shown in Figure 14 .
[0035] A production line produces Φ16 mm ribbed steel bars according to the above four-split production process. Mechanical property tests are carried out on all Φ16 mm ribbed steel bars obtained from this production line. The yield strength is in the range of 435 - 445 MPa, the tensile strength is in the range of 610 - 630 MPa, and the strength ratio is in the range of 1.39 - 1.42. From the test results of the mechanical properties, it can be seen that the quality control of the four-split production process provided by the present invention is good, the consistency within batches of Φ16 mm ribbed steel bars on the same production line is high, homogeneous production is achieved, and the high-standard quality controllability requirements are met.
[0036] Example 2 A four-split production process for Φ16 mm ribbed steel bars, in which the obtained chemical composition components are successively subjected to billet heating, rolling, controlled rolling and controlled cooling, and finishing and collecting to obtain Φ16 mm ribbed steel bars; Specifically, it includes the following steps: Step One: Batch mixing. By mass percentage, the chemical composition components include C 0.25%, Si 0.55%, Mn 1.60%, P 0.039%, S 0.040%, and the rest are Fe and inevitable impurities; Step Two: Billet heating. The starting rolling temperature is 960°C. In the three-split production process of Φ16 mm ribbed steel bars, the starting rolling temperature is usually in the range of 965 - 1000°C. The starting rolling temperature is reduced by more than 40°C. With the temperature reduction, the coal consumption and alloy cost are correspondingly reduced; The furnace gas temperature in the first heating zone: the left top temperature is 850 °C, the right top temperature is 850 °C, the left side wall temperature is 850 °C, and the right side wall temperature is 850 °C; the furnace gas temperature in the third heating zone: the left top temperature is 860 °C, the right top temperature is 860 °C, the left side wall temperature is 930 °C, and the right side wall temperature is 930 °C; the furnace gas temperature in the soaking zone: the left top temperature is 1000 °C, the right top temperature is 1000 °C, the left side wall temperature is 940 °C, and the right side wall temperature is 940 °C; Step 3: Rolling, using the split rolling pass and stock shape system of K7 flat roll + K6 flat roll + K5 vertical box pass + K4 symmetric round pre-split pass + K3 symmetric round split pass + K2 single arc ellipse pass + K1 finishing pass (as Figures 1 - 7 shown), and compiling a rolling program table; Among them, for the K7 flat roll: starting from the perspective of improving production smoothness, the stock shape height is precisely controlled at 32.5 mm, and the stock shape width is 92.8 mm; For the K6 flat roll: to ensure the reduction of the K5 pass and the stability of the stock shape, the stock shape height is 24 mm, and the stock shape width is 95 mm; For the K5 vertical box pass: to alleviate the overload and line difference problems of the 15th stand, the bottom width of the groove is designed to be 20.5 mm, the width of the groove opening is designed to be 26.5 mm, the fillet is designed to be R3.5 mm, and the height of the pass is designed to be 80 mm; to ensure that when the stock shape of the subsequent passes and the fullness of the transverse ribs are adjusted as required, it cannot be too small, and the rolling load is above 12%, usually controlled at 40% - 60%; For the K4 symmetric round pre-split pass: Pre-splitting is the key pass for split production, directly affecting the line difference and dimensions of the finished product. To ensure the fullness of both side lines and the wear amount, the K4 symmetric round pre-split pass is designed as a round pass with the middle line area 2% - 3% smaller than the side line area. The height of the K4 pass is 20.7 mm, the width of the pass is 88 mm, the width of the groove opening at both side lines is 21.5 mm, and the width of the middle two lines is 22.5 mm. Based on the controlled rolling temperature state where the middle line temperature is lower than the side line temperature, such a pass design is conducive to the control of the negative tolerance uniformity of the four-line finished product; For the K3 symmetric round split pass: Regularize the two-line stock shape of the rolled piece to prepare the stock shape for splitting. The best range of the elongation coefficient for this pass is between 1.10 and 1.25. According to experience and the characteristics of the finished product dimensions, the thickness of the split zone of the K3 symmetric round split pass is designed to be 1.4 mm. If the split zone is too thick or too wide, it cannot be pressed in the K2 pass, resulting in early rolling marks in the finishing pass, and at the same time, the splitting wheel is overloaded, causing the accident of burning the bearing of the guide guard. If the split zone is too thin, the split zone is directly rolled onto the surface of the K2 stock, resulting in folding in the finishing pass; the K3 symmetric round split pass is designed as a round split pass with the middle line area 2% smaller than the side line area. Both of the middle two lines are 18.97 mm, both of the side lines are 19.04 mm, the total width is 89.5 mm, and the width of each line is 22.25 mm; K2 single-arc elliptical hole: To ensure the height of the finished product's transverse ribs, it is designed as an elliptical hole type. The height of the stock shape is 12.8 mm, and the width of the stock shape is 29.37 mm. K1 finished product hole: The height of the stock shape is 15.1 mm, and the width of the stock shape is 15.01 mm. For the stability of the stock shape during the production process and to reduce or avoid quality problems such as product size fluctuations caused by unstable stock deviation, all of K1 - K7 use imported rolling guide guard structures. Step 4: Controlled rolling and controlled cooling. A 29.5×97 mm water pipe is used, and the controlled rolling temperature is 900°C. Optimize and transform the structure of the cooling nozzles of the controlled rolling water tank to reduce the yin-yang surface and non-uniformity of the rolled piece. The condition parameters of the controlled rolling nozzles for Φ16 mm ribbed steel bars during three-split rolling are optimized and improved as follows: (1) Keep the appearance and assembly dimensions of the controlled rolling water tank cooling nozzles for Φ16 mm ribbed steel bars during three-split rolling unchanged. When producing Φ16 mm ribbed steel bars in four-split rolling, open the internal water path of the controlled rolling water tank cooling nozzles to introduce cooling water into the second cavity part of the nozzles to prepare for spraying and cooling the intermediate replacement core. Before the transformation, the schematic diagram of the controlled rolling water tank cooling nozzles for Φ16 mm ribbed steel bars during three-split rolling is shown in Figure 8 , and after the transformation, the schematic diagram of the controlled rolling water tank cooling nozzles for Φ16 mm ribbed steel bars during four-split rolling is shown in Figure 9 ; (2) Transform the intermediate replacement core in the controlled rolling water tank cooling nozzles. The top and bottom air dispersion holes in the middle section of the intermediate replacement core for Φ16 mm ribbed steel bars during three-split rolling are transformed into a flared + straight-line spraying slit. The width of the spraying slit is 2 mm, and the opening angle is 60°. Canceling the top and bottom air dispersion holes in the middle section of the intermediate replacement core for Φ16 mm ribbed steel bars during three-split rolling can ensure the spraying pressure. The size of the intermediate replacement core is 35.5×96 mm, ensuring that the rolled piece is suspended 3 mm above and below at this position to improve uniformity; Before the transformation, the front schematic diagram of the intermediate replacement core of the controlled rolling water tank cooling nozzles for Φ16 mm ribbed steel bars during three-split rolling is shown in Figure 10 ; after the transformation, the front schematic diagram of the intermediate replacement core of the controlled rolling water tank cooling nozzles for Φ16 mm ribbed steel bars during four-split rolling is shown in Figure 11 ; before the transformation, the side schematic diagram of the intermediate replacement core of the controlled rolling water tank cooling nozzles for Φ16 mm ribbed steel bars during three-split rolling is shown in Figure 12 ; after the transformation, the side schematic diagram of the intermediate replacement core of the controlled rolling water tank cooling nozzles for Φ16 mm ribbed steel bars during four-split rolling is shown in Figure 13 ; (3) Do not adjust the size of the imported plug-in in the controlled rolling water tank cooling nozzles. The inner hole size is 29.5×96.0 mm, which is the same as that of the controlled rolling water tank cooling nozzles for Φ16 mm ribbed steel bars during three-split rolling; When the Φ16 mm ribbed steel bar is triple-split, the midline temperature is 60 °C higher than the side line temperature. By optimizing and transforming the structure of the cooling nozzles of the controlled rolling water tank, the temperature difference between the midline and the side line is reduced, and the temperature of the midline is only 30 °C higher than that of the side line; Step Five: After finishing and collecting by the conventional method, the quadruple-split Φ16 mm ribbed steel bar is obtained, and its metallographic structure meets the national standard requirements. The metallographic structure diagram is shown in Figure 15 .
[0037] A production line produces Φ16 mm ribbed steel bars according to the above quadruple-split production process. Mechanical property tests are carried out on all Φ16 mm ribbed steel bars obtained from this production line. The yield strength is in the range of 435 - 445 MPa, the tensile strength is in the range of 610 - 630 MPa, and the strength ratio is in the range of 1.39 - 1.42. From the test results of the mechanical properties, it can be seen that the quadruple-split production process provided by the present invention has good quality control, high consistency within batches of Φ16 mm ribbed steel bars on the same production line, realizes homogenized production, and meets the requirements of high-standard quality controllability.
[0038] Comparative Example 1 A triple-split production process for Φ16 mm ribbed steel bars, in which the chemical component groups obtained by batch matching are successively subjected to billet heating, rolling, controlled rolling and controlled cooling, and finishing and collecting to obtain Φ16 mm ribbed steel bars; Specifically, it includes the following steps: Step One: Batch matching. By mass percentage, the chemical component groups include C 0.22%, Si 0.75%, Mn 1.40%, P 0.045%, S 0.045%, and the rest are Fe and unavoidable impurities; Step Two: Billet heating, the starting rolling temperature is 1000 °C; The furnace gas temperature in the first heating section: the left top temperature is 750 °C, the right top temperature is 750 °C, the left side wall temperature is 750 °C, and the right side wall temperature is 750 °C; the furnace gas temperature in the third heating section: the left top temperature is 940 °C, the right top temperature is 940 °C, the left side wall temperature is 1010 °C, and the right side wall temperature is 1010 °C; the furnace gas temperature in the soaking section: the left top temperature is 920 °C, the right top temperature is 920 °C, the left side wall temperature is 1020 °C, and the right side wall temperature is 1020 °C; Step Three: Rolling, adopting the split rolling pass system and stock shape system of K7 flat roll + K6 flat roll + K5 vertical box pass + K4 symmetric round hole pre-splitting pass + K3 symmetric round hole splitting pass + K2 single arc oval pass + K1 finished product pass (as Figures 1 - 7 shown), and compiling a rolling program table; Among them, for the K7 flat roll: from the perspective of improving production smoothness, the stock shape height is accurately controlled at 32.5 mm, and the stock shape width is 92.8 mm; K6 Horizontal Roll: To ensure the reduction amount and profile stability of K5, for a stock profile height of 95 mm, the height is 24 mm and the width is 95 mm. K5 Vertical Box Pass: To alleviate the overload and line difference problems of Stand 15, the bottom width of the pass is designed to be 20.5 mm, the width of the pass opening is designed to be 26.5 mm, and the fillet is designed to be R3.5 mm; the height of the pass profile is designed to be 80 mm; to ensure that when the profile of the subsequent stands and the fullness of the transverse ribs are adjusted as required, it cannot be too small, and the rolling load is above 12%, usually controlled between 40% and 60%. K4 Symmetric Round Hole Pre-splitting Pass: Pre-splitting is a key pass in the splitting production, which directly affects the line difference and dimensions of the finished product. To ensure the fullness of both sides and the wear amount, the K4 symmetric round hole pre-splitting pass profile is designed as a round hole profile with the central line area 2% - 3% smaller than the side line area. The height of the K4 pass profile is 20.7 mm, the width is 88 mm, the width of the pass opening at both side lines is 21.5 mm, and the width of the middle two lines is 22.5 mm. According to the controlled rolling temperature state where the temperature of the central line is lower than that of the side lines, such a pass profile design is conducive to the control of the negative tolerance uniformity of the four-line finished product. K3 Symmetric Round Hole Splitting Pass: Regularize the two-line profile of the rolled piece to prepare the profile for splitting. The best range of the elongation coefficient for this pass is between 1.10 and 1.25. According to experience and the characteristics of the finished product dimensions, the thickness of the splitting zone of the K3 symmetric round hole splitting pass is designed to be 1.4 mm. If the splitting zone is too thick or too wide, it cannot be pressed together in the K2 pass, resulting in early rolling marks in the finished pass profile, and at the same time, the splitting wheel is overloaded, causing the accident of burning the bearing of the guide guard. If the splitting zone is too thin, the splitting zone will be directly rolled onto the surface of the K2 stock, resulting in folding in the finished pass. The K3 symmetric round hole splitting pass profile is designed as a round splitting pass profile with the central line area 2% smaller than the side line area. The middle two lines are both 18.97 mm, the two side lines are both 19.04 mm, the total width is 89.5 mm, and the width of each line is 22.25 mm. K2 Single Arc Elliptical Pass: To ensure the height of the transverse ribs of the finished product, it is designed as an elliptical pass profile, with the profile height of 12.8 mm and the profile width of 29.37 mm. K1 Finishing Pass: The profile height is 15.1 mm and the profile width is 15.01 mm. To ensure the stability of the profile during the production process and reduce or avoid quality problems such as product size fluctuations caused by unstable material deviation, all of K1 - K7 use imported rolling guide guard structures. Step 4: Controlled Rolling and Controlled Cooling. A water pipe with a size of 29.5×97 mm is used, and the controlled rolling temperature is 850°C; a controlled rolling nozzle for Φ16 mm threaded steel three-splitting is used. The schematic diagram of the controlled rolling water tank cooling nozzle for Φ16 mm threaded steel three-splitting is shown in Figure 8 , and the front schematic diagram of the intermediate replacement core of the controlled rolling water tank cooling nozzle for Φ16 mm threaded steel three-splitting is shown in Figure 10; The side schematic diagram of the intermediate replacement core of the cooling nozzle of the controlled rolling water tank for the three-split of Φ16 mm ribbed steel bars is shown in Figure 12 ; When the Φ16 mm ribbed steel bars are three-split, the midline temperature is 60 °C higher than that of the side lines; Step Five: After finishing and collecting by the conventional method, the three-split Φ16 mm ribbed steel bars are obtained.
[0039] A production line produces Φ16 mm ribbed steel bars according to the above three-split production process. Mechanical property tests are carried out on all Φ16 mm ribbed steel bars obtained from this production line. The yield strength is in the range of 430 - 455 MPa, the tensile strength is in the range of 610 - 630 MPa, and the strength ratio is in the range of 1.39 - 1.42. From the test results of the mechanical properties, it can be seen that the quality control of the traditional three-split production process is relatively poor, and the yield strength difference is 25 MPa. For the 16 mm ribbed steel bars obtained by using the four-split production process provided by the present invention, the yield strength difference is within 10 MPa. Thus, it can be seen that the within-batch consistency of the three-split Φ16 mm ribbed steel bars on the same production line is relatively low, and the difference in the yield strength between Φ16 mm ribbed steel bars is relatively large.
[0040] Moreover, after changing the three-split process of Φ16 mm ribbed steel bars to the four-split process of Φ16 mm ribbed steel bars, the power consumption is reduced by 6.5 kwh / t, the coal consumption is reduced by 5 kg / t, the hourly output is increased by 54.2 t / h, the power consumption and coal consumption costs can be reduced by 9.6 yuan / t, the hourly output is increased by 18.5%, and the annual profit and tax benefits can reach more than 60 million yuan. The product cost is reduced, and the market competitiveness is improved.
[0041] All in all, the present invention optimizes the temperature control, pass system design and controlled rolling water tank cooling nozzle, reduces costs and improves product accuracy and process stability. The starting rolling temperature is reduced to 920 - 960 °C, compared with 965 - 1000 °C of the traditional three-split, reducing fuel consumption and alloy burning loss. The split rolling pass and stock shape system with optimized parameter design are adopted, especially the optimization of the parameters of the K4 symmetric round hole pre-split pass. The midline area is 2% - 3% smaller than that of the side lines, and the middle wire groove width is widened by 1 mm to compensate for the difference in metal flow, so that the elongation coefficients of the four-line rolled pieces are consistent. The structure of the intermediate replacement core of the controlled rolling water tank cooling nozzle is transformed, the air dispersion holes are changed to a water spraying slit combined with a flared mouth and a straight line segment, the water flow path is optimized, and combined with the suspended layout of the rolled piece, the surface quality and mechanical properties of the four-line rolled piece are improved. Through innovations in multiple links, the present invention realizes the stable application of the four-split process of Φ16 mm ribbed steel bars.
[0042] Although the present invention has been described in detail by reference to the accompanying drawings and in conjunction 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 all such modifications or substitutions should 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 conceive of changes or substitutions, which should all be covered within the protection scope of the present invention.
Claims
1. A four-cut production process for Φ16 mm threaded steel bars, characterized in that: After batching, the steel billet is heated, rolled, controlled rolled and cooled, and finished and collected to obtain four-cut Φ16 mm threaded steel bars; After the billet is heated, the rolling temperature is 920-960℃; During rolling, the cutting and rolling hole type and material type system of K7 flat roller + K6 flat roller + K5 vertical box hole + K4 symmetrical circular hole pre-cut hole + K3 symmetrical circular hole cutting hole + K2 single arc elliptical hole + K1 finished hole is adopted. The K4 symmetrical circular hole pre-cut hole is a circular hole type with a center line area 2% to 3% smaller than the side line area. The hole height is 20.7 mm, the hole width is 88 mm, the two side lines of the slot width are 21.5 mm, and the two middle lines are 22.5 mm. During controlled rolling and controlled cooling, a controlled rolling water tank with an internal water channel is used to cool the nozzle. The internal water channel introduces cooling water into the second cavity part of the nozzle. The top and bottom surfaces of the middle section of the middle core replacement of the controlled rolling water tank cooling nozzle are designed as a bell mouth + straight section water spray seam, and the size of the middle core replacement is 35.5×96 mm.
2. The four-cut production process of a Φ16 mm threaded steel bar according to claim 1, characterized in that: The chemical composition of the batch is calculated by mass percentage, including C 0.22%~0.25%, Si 0.55%~0.75%, Mn 1.40%~1.60%, P ≤ 0.045%, S ≤ 0.045%, and the rest is Fe and unavoidable impurities.
3. The four-cut production process of a Φ16 mm threaded steel bar according to claim 1, characterized in that: When the steel billet is heated, the furnace gas temperature of the heating section is: the left top temperature is 750-850°C, the right top temperature is 750-850°C, the left wall temperature is 750-850°C, and the right wall temperature is 750-850°C; the furnace gas temperature of the heating section is: the left top temperature is 860-940°C, the right top temperature is 860-940°C, the left wall temperature is 930-1010°C, and the right wall temperature is 930-1010°C; the furnace gas temperature of the soaking section is: the left top temperature is 920-1000°C, the right top temperature is 920-1000°C, the left wall temperature is 940-1020°C, and the right wall temperature is 940-1020°C.
4. The four-cut production process of a Φ16 mm threaded steel bar according to claim 1, characterized in that: The material height of the K7 flat roller is 32.5 mm ± 1 mm, and the material width is 92.8 mm ± 1 mm; the material height of the K6 flat roller is 24 mm ± 1 mm, and the material width is 95 mm ± 1 mm.
5. The four-cut production process of Φ16 mm threaded steel bars according to claim 1, characterized in that: The groove bottom width of the K5 vertical box hole is 20.5 mm, the groove mouth width is 26.5 mm, the fillet is R3.5 mm, the hole height is 80 mm, and the rolling load is ≥12%; the elongation coefficient of the K3 symmetrical circular hole cutting hole is 1.10-1.25, the cutting band thickness is 1.4 mm, and the center line area of the K3 symmetrical circular hole cutting hole is 2% smaller than the side line area. The two middle lines are both 18.97 mm, and the two side lines are both 19.04 mm. The total width is 89.5 mm, and the width of each line is 22.25 mm.
6. The four-cut production process of Φ16 mm threaded steel bars according to claim 1, characterized in that: The material height of the K2 single arc elliptical hole is 12.8 mm ± 1 mm, and the material width is 29.37 mm ± 1 mm; the material height of the K1 finished hole is 15.1 mm ± 1 mm, and the material width is 15.01 mm ± 1 mm.
7. The four-cut production process of Φ16 mm threaded steel bars according to claim 1, characterized in that: K1~K7 all use imported rolling guide structure.
8. The four-cut production process of Φ16 mm threaded steel bars according to claim 1, characterized in that: During controlled rolling and controlled cooling, a 29.5×97 mm water pipe is used and the controlled rolling temperature is 850~900℃.
9. The four-cut production process of Φ16 mm threaded steel bars according to claim 1, characterized in that: The width of the straight section water spray gap of the controlled rolling water tank cooling nozzle is 2mm, and the opening angle is 60°.
10. The four-cut production process of Φ16 mm threaded steel bars according to claim 1, characterized in that: The inner hole size of the inlet plug in the controlled rolling water tank cooling nozzle is 29.5×96.0 mm.