A three-way rolling method for ribbed threaded steel bars

Abstract

The application discloses a three-split rolling method of ribbed steel bars, and the heated square billet is sequentially subjected to rough rolling, medium rolling and finish rolling; in the finish rolling process, the initial rolling piece is rolled through a box-shaped hole to form a spread rolling piece, the spread rolling piece is rolled through a pre-cut hole to form three parallel rolling units, and a pre-cut part is formed between the adjacent rolling units; the pre-cut rolling piece is rolled through a cutting hole, so that the pre-cut part is compressed to form a cutting strip, and the three-split rolling piece is separated along the cutting strip to form three strands of the three-split rolling piece; the three strands of the three-split rolling piece are rolled through flat-bottomed oval holes respectively and then enter product holes to form the ribbed steel bars. The application can realize stable three-split rolling of the ribbed steel bars, can improve the hourly output while reducing the rolling speed, and is favorable for reducing the equipment operation load and the rolling piece torsion risk and improving the rolling stability.

Description

Technical Field

[0001] This invention belongs to the field of threaded steel bar rolling technology, specifically a three-section rolling method for ribbed threaded steel bars. Background Technology

[0002] Ribbed threaded steel bars are commonly used steel products in construction engineering. Their production process typically involves heating a square billet and then sequentially undergoing rough rolling, intermediate rolling, and finish rolling to gradually elongate the billet and form finished steel bars that meet specifications. For Φ22mm ribbed threaded steel bars, increasing the hourly output of the rolling production line, while ensuring product dimensions and surface quality, is an important way to improve production efficiency and reduce unit product depreciation and labor costs.

[0003] The current production process of Φ22mm ribbed threaded steel bars typically employs a two-stage rolling method. When further increasing hourly output is required, the output per unit time can be increased by raising the rolling speed. However, as the rolling speed increases, the operating speed of the rolling mill and subsequent conveying equipment also increases. The mechanical load and vibration experienced by the equipment under high-speed operation increase, making it more susceptible to equipment failure and damage. Simultaneously, the increased rolling speed also increases the speed at which the finished steel bars enter the cooling bed. When the steel bars enter the cooling bed at high speed, collisions and abnormal stacking can easily occur, thus affecting the stability of the production process and the product qualification rate.

[0004] Therefore, the existing two-splitting rolling method for Φ22mm ribbed threaded steel bars faces the problem of mutual constraints between output increase and rolling speed, equipment operating load and upper cooling bed speed when further increasing hourly output. It is necessary to provide a rolling method for ribbed threaded steel bars that can increase hourly output while reducing rolling speed, and take into account rolling stability and product quality. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology and solve at least one of the problems mentioned in the background technology, a three-section rolling method for ribbed threaded steel bars is proposed.

[0006] The technical solution adopted by the present invention to solve its technical problem is: a three-section rolling method for ribbed threaded steel bars, comprising: sequentially performing rough rolling, intermediate rolling and finish rolling on heated square billets;

[0007] Finish rolling includes the following steps: S1. The initial rolled piece after intermediate rolling is rolled into a wide rolled piece by box-type rolling; S2. The wide-spreading rolled piece is rolled through a pre-cutting hole to form a pre-cut rolled piece. The pre-cut rolled piece forms three parallel rolling units in its width direction, and a pre-cut section is formed between two adjacent rolling units. S3. The pre-cut rolled piece is rolled through the slitting hole, which further thins the pre-cut part between two adjacent rolling units to form a slitting strip, and the three rolling units are separated along the slitting strip to form three-strand slitting rolled pieces; S4. The three-strand split rolled pieces are rolled into flat-bottomed elliptical rolled pieces through flat-bottomed elliptical holes respectively; S5, three flat-bottomed elliptical rolled pieces are rolled into the finishing hole to form ribbed threaded steel bars.

[0008] Furthermore, the diameter of the ribbed threaded steel bar is 22mm, and the specifications of the square billet are 160mm×160mm×12000mm.

[0009] Furthermore, the billet is heated in a walking beam furnace and then rolled; the roughing, intermediate and finishing mills all use six-stand mills, with the roughing and intermediate mills arranged alternately in horizontal and vertical configurations.

[0010] Furthermore, the roughing mill uses a six-stand mill, namely the 1st stand, 2nd stand, 3rd stand, 4th stand, 5th stand and 6th stand; among them, the 1st stand, 2nd stand and 3rd stand all use flat roll holes, the 4th stand uses round holes, the 5th stand uses elliptical holes, and the 6th stand uses round holes.

[0011] Furthermore, the intermediate rolling mill adopts a six-stand rolling mill, namely the 7th stand, 8th stand, 9th stand, 10th stand, 11th stand and 12th stand; among them, the 7th stand uses an elliptical hole, the 8th stand is skipped, the 9th stand uses a flat roll hole, the 10th and 11th stands are skipped, and the 12th stand uses a flat roll hole.

[0012] Furthermore, the six stands of the finishing mill are K6 stand, K5 stand, K4 stand, K3 stand, K2 stand and K1 stand in sequence; among them, K6 stand is a no-pass stand, K5 stand uses box-shaped holes, K4 stand uses pre-cut holes, K3 stand uses split holes, K2 stand uses flat-bottomed elliptical holes, and K1 stand uses finished holes; K5 stand is a vertical rolling stand, K4 stand, K3 stand and K2 stand are all horizontal rolling stands, and K1 stand is a horizontal-vertical convertible stand.

[0013] Furthermore, the center lines of the three rolling units in the pre-cutting workpiece are set at equal intervals along the width direction of the pre-cutting workpiece, and the distance between the center lines of two adjacent rolling units is 31mm; the total transverse width of the pre-cutting hole is 93mm and the height is 29mm.

[0014] Furthermore, the center lines of the three rolling units in the slitting hole are set at equal intervals along the width direction of the workpiece, and the distance between the center lines of two adjacent rolling units is 31mm; the total transverse width of the slitting hole is 94mm and the height is 27mm, and the thickness of the slitting strip formed by rolling through the slitting hole is 1.0mm.

[0015] Furthermore, the horizontal width of the flat-bottomed oval hole is 40mm, the maximum height is 17mm, the width of the flat bottom section of the flat-bottomed oval hole is 10mm, and the hole height at the openings on both sides is 4mm.

[0016] Furthermore, the extension coefficients of racks #2, #3, #4, #5, #6, #7, #9, #12, K5, K4, K3, and K2 are 1.24, 1.32, 1.25, 1.29, 1.25, 1.21, 1.18, 1.15, 1.31, 1.19, 1.12, and 1.21, respectively.

[0017] The beneficial effects of this invention are as follows: 1. This invention involves sequentially roughing, intermediate rolling, and finishing rolling of heated square billets. During the finishing rolling process, box-shaped holes, pre-cut holes, split holes, flat-bottomed elliptical holes, and finishing holes are used for rolling. This process transforms a single-strand rolled piece into a three-strand split rolled piece after widening, pre-cutting, and splitting. These three pieces then enter subsequent holes to complete the finished product rolling, thereby achieving continuous three-splitting production of ribbed threaded steel bars. This invention can increase the output of finished products per unit time by simultaneously rolling three-strand rolled pieces. This allows for increased hourly output while reducing rolling speed, and also reduces the operating speed of downstream equipment and the speed of the cooling bed, minimizing the adverse effects of high-speed operation on the equipment and improving the stability of rolling production.

[0018] 2. This invention forms three parallel rolling units in the width direction of the pre-cut piece through pre-cutting holes, and forms pre-cut sections between adjacent rolling units. The pre-cut sections are then further thinned through slitting holes to form a slitting strip, enabling the three rolling units to separate along predetermined positions to form three-strand slitting pieces. This makes the three-slitting positions clearer and helps improve the stability of the separation process of the three-strand pieces. Furthermore, setting the thickness of the slitting strip to 1.0 mm can reduce the resistance during separation along the slitting strip, reduce the workload and wear of the slitting wheel, and reduce the amount of metal in the slitting strip area, thus reducing the adverse effects of the low temperature in this area during cooling on the surface quality of the finished steel bar.

[0019] 3. The present invention provides a flat-bottomed elliptical hole after the slitting hole, so that the three slitting rolled pieces pass through the flat-bottomed elliptical hole for cross-sectional shaping. The flat-bottomed elliptical hole constrains the material shape and rolling posture of the slitting rolled pieces, reducing the possibility of twisting of the three slitting rolled pieces during subsequent conveying and rolling processes. This allows each rolled piece to enter the finishing hole with a more stable material shape, thereby improving the stability of the three-slitting rolling process and the finished product rolling process. Attached Figure Description

[0020] Figure 1 This is a schematic flowchart of the three-section rolling method for ribbed threaded steel bars according to the present invention; Figure 2 This is a schematic diagram of the flat roller hole structure of frame #1 in this invention; Figure 3 This is a schematic diagram of the flat roller hole structure of frame #2 in this invention; Figure 4 This is a schematic diagram of the flat roller hole structure of frame #3 in this invention; Figure 5 This is a schematic diagram of the circular hole structure of frame #4 in this invention; Figure 6 This is a schematic diagram of the elliptical hole structure of frame #5 in this invention; Figure 7 This is a schematic diagram of the circular hole structure of frame #6 in this invention; Figure 8 This is a schematic diagram of the elliptical hole structure of frame #7 in this invention; Figure 9 This is a schematic diagram of the flat roller hole structure of frame #9 in this invention; Figure 10 This is a schematic diagram of the flat roller hole structure of frame #12 in this invention; Figure 11 This is a schematic diagram of the box-shaped hole structure of the K5 frame in this invention; Figure 12 This is a schematic diagram of the pre-cut hole structure of the K4 frame in this invention; Figure 13 This is a schematic diagram of the splitting hole structure of the K3 frame in this invention; Figure 14 This is a schematic diagram of the flat-bottomed elliptical hole structure of the K2 frame in this invention. Detailed Implementation

[0021] To illustrate in detail the technical solutions adopted by the present invention to achieve the intended technical objectives, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Furthermore, the technical means or technical features in the embodiments of the present invention can be replaced without creative effort. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0022] This embodiment provides a three-stage rolling method for ribbed threaded steel bars, mainly used for the production of ribbed threaded steel bars with a diameter of 22mm. The rolling raw material is a square billet with specifications of 160mm×160mm×12000mm. The billet is first fed into a walking beam furnace for heating. After heating, the billet passes through roughing, intermediate rolling, and finishing rolling in sequence. The roughing, intermediate rolling, and finishing rolling all use six-stand rolling mills to form a continuous eighteen-stand rolling arrangement. The roughing and intermediate rolling mills are arranged alternately in horizontal and vertical positions to gradually complete the reduction, elongation, and shape adjustment of the billet, and to form the initial rolled piece that meets the requirements of the subsequent three-stage finishing rolling.

[0023] Specifically, the roughing mill includes six stands arranged sequentially: #1, #2, #3, #4, #5, and #6. Stands #1, #2, and #3 use flat roll passes, stand #4 uses round roll passes, and stand #5 uses elliptical roll passes. The heated billet passes through these six roughing mill stands sequentially, allowing it to gradually elongate during continuous pressing. The width and thickness of the rolled piece are adjusted through continuous shape changes between flat roll passes, round roll passes, and elliptical roll passes, providing a relatively stable roughing mill piece in shape and size for subsequent intermediate rolling.

[0024] After roughing, the workpiece enters the intermediate rolling zone, which includes stands 7, 8, 9, 10, 11, and 12 arranged sequentially. Stand 7 uses an elliptical pass, stand 8 is idle, stand 9 uses a flat roll pass, stands 10 and 11 are idle, and stand 12 uses a flat roll pass. The rough-rolled workpiece first undergoes further shape adjustment through the elliptical pass of stand 7, then idles through stand 8, and is rolled through the flat roll pass of stand 9. It then sequentially idles through stands 10 and 11, and finally is rolled through the flat roll pass of stand 12 to form the initial workpiece for the finishing rolling zone. By combining the actual rolling stands with the idle stands in the intermediate rolling stage, the requirements for workpiece elongation and shape adjustment can be met while maintaining the cross-sectional shape of the initial workpiece after intermediate rolling suitable for the subsequent three-section finishing rolling.

[0025] The finishing mill comprises four stands arranged sequentially: K6, K5, K4, K3, K2, and K1. K6 is a pass-through stand, K5 uses a box-shaped bore, K4 uses a pre-cut bore, K3 uses a split bore, K2 uses a flat-bottomed elliptical bore, and K1 uses a finished bore. K5 uses vertical rolling, while K4, K3, and K2 use horizontal rolling. K1 is a convertible horizontal / vertical rolling mill. The initial rolled piece from the intermediate mill passes through K6 without pass-through and then sequentially passes through K5, K4, K3, K2, and K1 stands to complete the three-splitting finishing mill process. The specific process is as follows: Step S1: The initial rolled piece enters the K5 stand and is rolled through the box-shaped hole on the K5 stand. The box-shaped hole further presses down and widens the initial rolled piece, so that the cross-section of the initial rolled piece expands along its width direction to form a widened rolled piece. Through this step, the rolled piece entering the subsequent pre-cut hole has the lateral dimensions required to meet the parallel forming of the three rolling units, providing the corresponding material template basis for the subsequent three-splitting process.

[0026] In step S2, the wide-spreading rolled piece enters the K4 stand and is rolled through the pre-cutting holes on the K4 stand to form a pre-cut rolled piece. The pre-cutting holes form three parallel rolling units along the width direction of the rolled piece, so that the three rolling units are initially formed on the wide-spreading rolled piece, and pre-cut sections are formed between two adjacent rolling units. Thus, two pre-cutting positions are formed simultaneously in one pre-cutting rolling process, which establishes a predetermined cutting area for dividing one rolled piece into three rolled pieces in the future.

[0027] In this embodiment, the centerlines of the three rolling units in the pre-cut workpiece are equally spaced along the width direction of the workpiece, with a spacing of 31mm between the centerlines of two adjacent rolling units. Correspondingly, the distance between the centerlines of two rolling units located on both sides is 62mm. The total transverse width of the pre-cut hole is 93mm, and the height is 29mm. These hole dimensions allow the three rolling units and the two pre-cut sections located therebetween to be formed on the pre-cut workpiece at predetermined positions, ensuring that the material distribution of the three rolling units remains relatively consistent.

[0028] In step S3, the pre-cut rolled piece enters the K3 stand and is rolled through the slitting holes on the K3 stand. The slitting holes correspond to the three rolling units on the pre-cut rolled piece, and further press down the pre-cut portion between two adjacent rolling units to reduce the thickness of the two pre-cut portions and form slitting strips respectively. The three rolling units are separated along the two slitting strips to form a three-strand slitting rolled piece.

[0029] In this embodiment, the center lines of the three rolling units corresponding to the slitting hole are equally spaced along the width direction of the workpiece, the distance between the center lines of two adjacent rolling units is 31mm, the total lateral width of the slitting hole is 94mm, and the height is 27mm. After rolling through the slitting hole, a slitting band with a thickness of 1.0mm is formed between two adjacent rolling units. The two slitting bands are located between the three rolling units, so that the three rolling units can be separated along the predetermined slitting position, reducing the possibility of slitting position deviation or insufficient slitting.

[0030] In this embodiment, the thickness of the cutting strip in the three-splitting rolling process is set to 1.0 mm, which further reduces the connection area between adjacent rolling units. On the one hand, this helps to reduce the cutting resistance when separating along the cutting strip, thereby reducing the workload and wear of the cutting wheel corresponding to the K3 stand. On the other hand, since the amount of metal in the cutting strip is reduced, the adverse effects on the surface quality of the finished steel bar caused by the lower temperature of the torn area of ​​the cutting strip during the cooling process can be reduced.

[0031] In step S4, the three slit rolls enter the K2 stand and are rolled through the flat-bottomed elliptical holes on the K2 stand to form three flat-bottomed elliptical rolls. Since the pre-cut rolls are split into three independent slit rolls from one roll, each slit roll may deflect or twist during its entry into the next pass. Therefore, in this embodiment, a flat-bottomed elliptical hole is provided after the splitting hole. The three slit rolls are cross-sectionally shaped through the flat-bottomed elliptical hole, and the rolling posture of the rolls is constrained by the flat-bottomed structure, thereby improving the shape stability of the three rolls, reducing the possibility of twisting of the slit rolls, and enabling them to enter the subsequent finishing hole with a more stable posture.

[0032] Specifically, in this embodiment, the horizontal width of the flat-bottomed elliptical hole is 40mm, the maximum height is 17mm, the width of the flat bottom section of the flat-bottomed elliptical hole is 10mm, and the hole height at the openings on both sides is 4mm. After the cut-rolled workpiece passes through the above-mentioned flat-bottomed elliptical hole, its cross-section is adjusted to a flat-bottomed elliptical material shape suitable for entering the finished product hole. While completing the cross-sectional dimension adjustment, the posture stability of the workpiece before entering the finished product hole can be improved.

[0033] In step S5, the three flat-bottomed elliptical rolled pieces after being rolled in the flat-bottomed elliptical hole enter the K1 stand respectively and are rolled through the finished product hole on the K1 stand, so that the three flat-bottomed elliptical rolled pieces are simultaneously formed into ribbed threaded steel bars with a diameter of 22mm. Thus, the initial rolled piece entering the finishing rolling stage is widened by the box-shaped hole, pre-cut by the pre-cutting hole, cut by the splitting hole, and shaped by the flat-bottomed elliptical hole, and finally forms three finished ribbed threaded steel bars at the same time, realizing the three-splitting continuous rolling of Φ22mm ribbed threaded steel bars.

[0034] To ensure that the deformation of each rolling pass matches the aforementioned pass conversion process, this embodiment sets the elongation coefficients for some actual rolling stands. Specifically, the elongation coefficients for stands #2, #3, #4, #5, and #6 are 1.24, 1.32, 1.25, 1.29, and 1.25, respectively; for stands #7, #9, and #12, they are 1.21, 1.18, and 1.15, respectively; and for stands K5, K4, K3, and K2, they are 1.31, 1.19, 1.12, and 1.21, respectively. By matching the elongation coefficients of each pass with the corresponding pass shapes, the workpiece undergoes progressive section adjustment and elongation during roughing, intermediate rolling, and finishing rolling. This ensures that the workpiece entering the pre-cutting hole, splitting hole, and flat-bottomed elliptical hole has a material profile matching the corresponding pass shape, thereby improving the continuity and stability of the three-stage rolling process.

[0035] As a specific example of the die profile parameters, in the three-splitting rolling process of Φ22mm ribbed threaded steel bars, after entering the finishing rolling stage, the total transverse width of the pre-cut hole of the K4 stand is 93mm and the height is 29mm. The three rolling units in the pre-cut workpiece are equally spaced along the width direction of the workpiece, and the centerline distance between two adjacent rolling units is 31mm. The total transverse width of the split hole of the K3 stand is 94mm and the height is 27mm. The centerline distance between the three rolling units is maintained at 31mm. After rolling through the split hole, a splitting band with a thickness of 1.0mm is formed between two adjacent rolling units. The transverse width of the flat-bottomed elliptical hole of the K2 stand is 40mm and the maximum height is 17mm. The width of the flat bottom section is 10mm, and the die profile height at the openings on both sides is 4mm. By maintaining the corresponding lateral positional relationship between the three rolling units in the pre-cut hole and the split hole, and by matching the hole shape dimensions of the pre-cut hole, the split hole, and the flat-bottomed elliptical hole with the pre-cutting, splitting, and post-splitting shaping processes of the rolled piece, the wide rolled piece can sequentially complete the pre-forming, splitting strip forming, and material shape adjustment of the three split rolled pieces in the three rolling units, providing the corresponding material shape conditions for the three rolled pieces to stably enter the finished product hole.

[0036] Compared to the original two-splitting rolling method for Φ22mm ribbed threaded steel bars, the above-described three-splitting rolling method does not require simply increasing the rolling speed to increase hourly output. In actual production, the original two-splitting method has a rolling speed of approximately 14.5 m / s, an hourly output of approximately 260 t / h, and an upper cooling bed speed of approximately 16.5 m / s. After adopting the three-splitting rolling method of this embodiment, the rolling speed is reduced to approximately 12.4 m / s, the hourly output is increased to approximately 330 t / h, and the upper cooling bed speed is reduced to approximately 14 m / s. Therefore, the output of finished products per unit time can still be increased while reducing the rolling speed and upper cooling bed speed.

[0037] Meanwhile, due to the reduced operating speed of downstream equipment, the vibration during equipment operation and the mechanical load caused by high-speed conditions can be reduced accordingly, resulting in a decrease of approximately 20% in equipment failure rate during actual production. As the speed of the upper cooling bed decreases, the occurrence of steel collisions when the steel bars enter the cooling bed at high speed is significantly reduced, and steel collision accidents are practically zero. After the stability of the rolling process is improved, the finished product qualification rate increases from approximately 99.91% to approximately 99.96%. Therefore, this embodiment achieves three-section rolling of Φ22mm ribbed threaded steel bars while taking into account production efficiency, rolling stability, and the reliability of downstream equipment operation through the continuous coordination between box-shaped widening, three-unit pre-cutting, double-splitting strip cutting, and flat-bottomed elliptical shaping after cutting.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A method for three-section rolling of ribbed threaded steel bars, characterized in that, include: The heated billet is subjected to rough rolling, intermediate rolling and finish rolling in sequence; The finishing rolling includes the following steps: S1. The initial rolled piece after intermediate rolling is rolled into a wide rolled piece by box-type rolling; S2. The wide-spreading rolled piece is rolled through a pre-cutting hole to form a pre-cut rolled piece. The pre-cut rolled piece forms three parallel rolling units in its width direction, and a pre-cut section is formed between two adjacent rolling units. S3. The pre-cut rolled piece is rolled through a slitting hole, which further thins the pre-cut portion between two adjacent rolling units to form a slitting strip, and the three rolling units are separated along the slitting strip to form a three-strand slitting rolled piece; S4. The three slit rolled pieces are respectively rolled through flat-bottomed elliptical holes to form flat-bottomed elliptical rolled pieces; S5. The three flat-bottomed elliptical rolled pieces are respectively rolled into the finishing hole to form ribbed threaded steel bars.

2. The three-section rolling method for ribbed threaded steel bars according to claim 1, characterized in that, The diameter of the ribbed threaded steel bar is 22mm, and the dimensions of the billet are 160mm×160mm×12000mm.

3. The three-splitting rolling method for ribbed threaded steel bars according to claim 2, characterized in that, The billet is heated in a walking beam furnace and then rolled; the roughing, intermediate and finishing mills all use six-stand mills, with the roughing and intermediate mills arranged alternately in horizontal and vertical configurations.

4. The three-section rolling method for ribbed threaded steel bars according to claim 3, characterized in that, The roughing mill uses a six-stand mill, namely the 1st stand, the 2nd stand, the 3rd stand, the 4th stand, the 5th stand and the 6th stand; among them, the 1st stand, the 2nd stand and the 3rd stand all use flat roll holes, the 4th stand uses round holes, the 5th stand uses elliptical holes, and the 6th stand uses round holes.

5. The three-splitting rolling method for ribbed threaded steel bars according to claim 4, characterized in that, The intermediate rolling mill uses a six-stand mill, namely the 7th stand, 8th stand, 9th stand, 10th stand, 11th stand and 12th stand in sequence; wherein the 7th stand has an elliptical roll hole, the 8th stand is passed without rolls, the 9th stand has a flat roll hole, the 10th and 11th stands are passed without rolls, and the 12th stand has a flat roll hole.

6. The three-section rolling method for ribbed threaded steel bars according to claim 5, characterized in that, The six stands of the finishing mill are K6 stand, K5 stand, K4 stand, K3 stand, K2 stand, and K1 stand, in sequence. Among them, K6 stand is a pass stand, K5 stand uses the box-shaped hole, K4 stand uses the pre-cut hole, K3 stand uses the slitting hole, K2 stand uses the flat-bottomed elliptical hole, and K1 stand uses the finished hole. K5 stand is a vertical rolling mill stand, K4 stand, K3 stand, and K2 stand are all horizontal rolling mill stands, and K1 stand is a horizontal-vertical convertible stand.

7. The three-section rolling method for ribbed threaded steel bars according to claim 6, characterized in that, The center lines of the three rolling units in the pre-cut rolled piece are equally spaced along the width direction of the pre-cut rolled piece, and the distance between the center lines of two adjacent rolling units is 31mm; the total transverse width of the pre-cut hole is 93mm and the height is 29mm.

8. The three-section rolling method for ribbed threaded steel bars according to claim 7, characterized in that, The center lines of the three rolling units corresponding to the slitting hole are equally spaced along the width direction of the workpiece, and the distance between the center lines of two adjacent rolling units is 31mm; the total transverse width of the slitting hole is 94mm and the height is 27mm, and the thickness of the slitting strip formed by rolling through the slitting hole is 1.0mm.

9. The three-section rolling method for ribbed threaded steel bars according to claim 6, characterized in that, The flat-bottomed elliptical hole has a horizontal width of 40mm and a maximum height of 17mm. The width of the flat bottom section of the flat-bottomed elliptical hole is 10mm, and the hole height at the openings on both sides is 4mm.

10. The three-section rolling method for ribbed threaded steel bars according to claim 6, characterized in that, The extension coefficients for racks #2, #3, #4, #5, #6, #7, #9, #12, K5, K4, K3, and K2 are 1.24, 1.32, 1.25, 1.29, 1.25, 1.21, 1.18, 1.15, 1.31, 1.19, 1.12, and 1.21, respectively.

Images