Method for preventing four-slitting rolled hot-rolled ribbed steel bar from being bent in cooling bed

Abstract

The invention discloses a method for avoiding steel bending of a four-slitting rolled hot-rolled ribbed steel bar on a cooling bed. The method comprises the following steps that hole pattern parameters of the middle and the two sides of a pre-slitting hole and a slitting hole are adjusted; a speed-adjustable conveying roller way set is additionally arranged between the rolled piece collecting area and the multiple-length shearing equipment; adjusting the width of a temporary fixed channel formed by a turning plate in a cooling bed input roller way; a fastening structure of a cooling bed input roller way roller is changed; the temperature gradient of the rolled piece is controlled, and the temperature difference between finished products in the middle and on the two sides is reduced through a cooling device; and the installation precision of the cooling bed straightening plate and the movable rack is adjusted. According to the method, the problems of waving of a cooling bed input roller way and arching of the cooling bed in the process of feeding the four-segmentation phi 12mm straight hot-rolled ribbed steel bars on the cooling bed in the double-length mode are solved, the steel bending defect in the process of feeding the four-segmentation phi 12mm straight hot-rolled ribbed steel bars on the cooling bed in the double-length mode is avoided, steel bending in the process of feeding the four-segmentation phi 12mm straight hot-rolled ribbed steel bars on the cooling bed in the double-length mode is avoided, and therefore the yield of the phi 12mm straight hot-rolled ribbed steel bars is

Description

Technical Field

[0001] The invention relates to the technical field of steel rolling, in particular to a method for avoiding steel bending in a cooling bed during four-cut rolling of hot-rolled ribbed steel bars. Background Art

[0002] In existing technology, 12mm Ø hot-rolled ribbed steel bars are produced using a four-cut rolling process. The finished 12mm Ø hot-rolled ribbed steel bars are sheared to multiple lengths using a 3# flying shear. The bars are then transported by a cooling bed input roller conveyor, braked by the skirt, and transferred to the cooling bed for straightening and cooling. After being cut to length and bundled, they are ready for sale.

[0003] When four-cut Ø12mm hot-rolled ribbed steel bars are fed to the cooling bed, waves and camber often occur on the cooling bed input rollers. This can cause the finished bars to become bent, increasing the amount of scrap. Furthermore, this problem requires a significant amount of time to adjust the process, seriously affecting production efficiency. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method for avoiding bending of hot-rolled ribbed steel bars in a cooling bed during four-cut rolling, so as to solve the problems raised by the above-mentioned background technology.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a method for avoiding bending of hot-rolled ribbed steel bars during four-cut rolling on a cooling bed, comprising the following steps:

[0006] Adjust the hole parameters in the middle and on both sides of the pre-cut holes and cut holes to reduce the difference in the conveying speed of multiple lengths;

[0007] Add an adjustable speed conveying roller set between the rolled product collection area and the double-length shearing equipment to suppress the decay of the finished product conveying speed;

[0008] Adjust the width of the temporary fixed channel formed by the flap in the cooling bed input roller to reduce the speed reduction of the edge length;

[0009] Change the fastening structure of the rollers of the cooling bed input roller table to prevent the rollers of the cooling bed input roller table from withdrawing abnormally;

[0010] Control the temperature gradient of the rolled piece and reduce the temperature difference between the middle and the finished products on both sides through the cooling device;

[0011] Adjust the installation accuracy of the cooling bed straightening plate and the moving rack to eliminate the multiple-length arching caused by mechanical misalignment.

[0012] As a further improvement of the present invention: the method of adjusting the hole parameters in the middle and on both sides of the pre-cut hole and the cut hole respectively includes:

[0013] The inner diameter of the middle hole of the pre-cut hole is smaller than the inner diameters of the two side holes, and the inner diameter of the middle hole of the cut hole is smaller than the inner diameters of the two side holes. The inner diameter of the middle hole of the pre-cut hole is 6.2mm, and the inner diameters of the two side holes of the pre-cut hole are 7.5mm. The inner diameter of the middle hole of the cut hole is 6.9mm, and the inner diameters of the two side holes of the cut hole are 7.0mm.

[0014] As a further improvement of the present invention: the speed-adjustable conveying roller set is added between the rolled piece collection area and the double-length shearing equipment, comprising:

[0015] The conveying roller set includes at least three sets of accelerable conveying rollers.

[0016] As a further improvement of the present invention: the adjusting of the width of the temporary fixed channel formed by the flap in the cooling bed input roller conveyor comprises:

[0017] Increase the width of the cooling bed input roller at the cover flap. The width of the temporary fixed channel formed in the cooling bed input roller at the cover flap is 120mm.

[0018] As a further improvement of the present invention: the fastening structure of the rollers of the cooling bed input roller table is changed, comprising:

[0019] The fastening structure includes 8 to 12 symmetrically distributed bolt holes, and each roller is fixed to the roller frame by at least two groups of bolts, each group including 2 to 4 bolts.

[0020] As a further improvement of the present invention: the controlling of the temperature gradient of the rolled piece comprises:

[0021] The starting rolling temperature of the rolled piece is controlled at 1030°C to 1050°C, and a group of cooling devices for cooling each finished product separately is added to the cooling pipe after rolling. The cooling device can adjust the cooling water volume of each finished product separately to reduce the temperature difference between the middle finished product and the finished products on both sides.

[0022] As a further improvement of the present invention: the installation accuracy adjustment of the cooling bed straightening plate and the movable rack includes:

[0023] When the straightening plates are installed, the multiple straightening positions between the straightening plates are calibrated by a laser positioning system, and the centers of the same straightening positions of the straightening plates are all on a straight line.

[0024] As a further improvement of the present invention: the installation accuracy adjustment of the cooling bed straightening plate and the movable rack also includes:

[0025] An up and down position fine-tuning device is added to the movable rack mounting base in each area, and the up and down position fine-tuning device adjusts the elevation of the movable rack during the production process.

[0026] As a further improvement of the present invention: the above-mentioned step of adding a speed-adjustable conveying roller set between the rolled piece collection area and the double-length shearing equipment further comprises:

[0027] Speed ​​sensors are installed at both ends of the cooling bed input roller. The speed sensors monitor the multiple-length conveying speed in real time. The speed sensors feed back the finished product conveying speed data to the PLC control system. The PLC control system dynamically adjusts the speed of the conveying roller according to the speed difference.

[0028] As a further improvement of the present invention: the method of controlling the temperature gradient of the rolled piece further includes:

[0029] Infrared thermometers are installed at the entrance and exit of the cooling bed to monitor the scale temperature in real time. The cooling device is connected to the thermometer signal and dynamically adjusts the cooling water volume according to the temperature data.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention adjusts the hole parameters in the middle and on both sides of the pre-slitting hole and the slitting hole, adds a speed-adjustable conveying roller group between the rolled piece gathering area and the double-length shearing device, adjusts the width of the temporary fixed channel formed by the flap in the cooling bed input roller, changes the fastening structure of the rollers of the cooling bed input roller, controls the temperature gradient of the rolled piece, increases the number of passes through the cooling device, and adjusts the installation accuracy of the cooling bed straightening plate and the movable rack. The present invention solves the problems of wave formation and arching of the cooling bed input roller in the process of putting four-slit Ф12mm hot-rolled ribbed steel bars on the double-length cooling bed, avoids the defect of bent steel in the process of putting the bars on the double-length cooling bed, and avoids the yield rate of the Ф12mm straight hot-rolled ribbed steel bars. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the method of the present invention. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] The present invention is further described with reference to the accompanying drawings and embodiments: A method for avoiding bending of hot-rolled ribbed steel bars during four-cut rolling on a cooling bed comprises the following steps:

[0035] Adjust the hole parameters in the middle and on both sides of the pre-cut holes and cut holes to reduce the difference in the conveying speed of multiple lengths;

[0036] Add an adjustable speed conveying roller set between the rolled product collection area and the double-length shearing equipment to suppress the decay of the finished product conveying speed;

[0037] Adjust the width of the temporary fixed channel formed by the flap in the cooling bed input roller to reduce the speed reduction of the edge length;

[0038] Change the fastening structure of the rollers of the cooling bed input roller table to prevent the rollers of the cooling bed input roller table from withdrawing abnormally;

[0039] Control the temperature gradient of the rolled piece and reduce the temperature difference between the middle and the finished products on both sides through the cooling device;

[0040] Adjust the installation accuracy of the cooling bed straightening plate and the moving rack to eliminate the multiple-length arching caused by mechanical misalignment.

[0041] The present invention addresses the problem of buckling and cambering on the cooling bed during the process of placing four-cut 12mm hot-rolled ribbed steel bars on a double-length cooling bed. By adjusting the hole parameters of the pre-cutting and cutting holes, the middle and side holes, adding an adjustable speed conveyor roller set between the workpiece collection area and the double-length shearing equipment, adjusting the width of the temporary fixed channel formed by the flaps in the cooling bed input rollers, changing the fastening structure of the cooling bed input rollers, controlling the temperature gradient of the workpiece, increasing the number of passes through the cooling device, and adjusting the installation precision of the cooling bed straightening plates and movable racks, the present invention solves the problems of waving and cambering on the cooling bed input rollers during the process of placing four-cut 12mm hot-rolled ribbed steel bars on a double-length cooling bed, thereby avoiding the occurrence of buckling defects during the process. Through these improvements, the yield rate of 12mm hot-rolled ribbed steel bars increased by 0.1%. Furthermore, because these issues were resolved, no extensive process adjustments were required, and the average hourly output of 12mm hot-rolled ribbed steel bars produced by four-cutting increased by 6.2 tons / hour.

[0042] In one embodiment of the present invention, the adjusting of the middle and side hole parameters of the pre-cut hole and the cut hole respectively includes:

[0043] The inner diameter of the middle hole of the pre-cut hole is smaller than the inner diameters of the two side holes, and the inner diameter of the middle hole of the cut hole is smaller than the inner diameters of the two side holes. The inner diameter of the middle hole of the pre-cut hole is 6.2mm, and the inner diameters of the two side holes of the pre-cut hole are 7.5mm. The inner diameter of the middle hole of the cut hole is 6.9mm, and the inner diameters of the two side holes of the cut hole are 7.0mm.

[0044] In this embodiment, the size of the finished product produced by the four-cut rolling process affects the speed of the multiple-length conveyor on the cooling bed input roller conveyor. The key factors influencing the finished product size are the pre-cutting and cutting pass shapes. The speed of the workpiece as it is conveyed on the roller conveyor is influenced by a combination of size, surface contact area, and friction. The smaller middle workpiece reduces contact area with the roller conveyor, resulting in lower friction and faster conveyor speeds. The larger workpieces on the sides experience increased friction and slower conveyor speeds. By designing differentiated pass shapes to adjust the size distribution of the four workpieces, the conveyor speed differences caused by positional differences can be reduced. When the inner diameters of the two middle holes of the pre-cutting and cutting holes are slightly smaller than the inner diameters of the two side holes, specifically, the inner diameter of the middle hole of the pre-cutting hole is smaller than the inner diameters of the two side holes, and the inner diameter of the middle hole of the cutting hole is smaller than the inner diameters of the two side holes. Preferably, the inner diameter of the middle hole of the pre-cutting hole is 6.2mm, the inner diameters of the two side holes of the pre-cutting hole are 7.5mm, the inner diameter of the middle hole of the cutting hole is 6.9mm, and the inner diameters of the two side holes of the cutting hole are 7.0mm. The difference in transportation speed of the four straight bars in the cooling bed input roller is the smallest, which can effectively prevent the straight bars from wavering due to this problem.

[0045] In one embodiment of the present invention, the step of adding a speed-adjustable conveying roller set between the rolled piece collection area and the double-length shearing device comprises:

[0046] The conveying roller group includes at least 3 groups of accelerable conveying rollers, and speed sensors are installed at the head and tail ends of the cooling bed input roller. The speed sensors monitor the multiple-length conveying speed in real time. The speed sensors feed back the finished product conveying speed data to the PLC control system, and the PLC control system dynamically adjusts the speed of the conveying roller according to the speed difference.

[0047] In this embodiment, the transport of the Ø12mm hot-rolled ribbed steel bars from the four-cut rolls to the 3# multiple-length flying shear is performed without a conveyor roller, relying solely on the bar's own speed. During this process, the finished product transport speed decreases sharply, exacerbating the speed differences between the finished products. This is one of the main reasons for the wave-like problem of Ø12mm hot-rolled ribbed steel bars on the cooling bed input roller conveyor. Three sets of accelerated conveyor rollers are added between the free guide trough where the finished products converge and the 3# multiple-length flying shear. This compensates for the speed drop in the original unpowered area, avoids the sharp speed drop of the finished products in the unpowered section, maintains the synchronous transport of the four multiple-length bars, and prevents accumulation or stretching caused by local speed differences. Speed ​​sensors are installed at both ends of the cooling bed input roller conveyor to monitor the speed of the multiple-length bars entering and leaving the roller sets in real time. The accelerated conveyor roller sets compensate for the natural deceleration of the finished products, and combined with PLC dynamic adjustment, eliminates speed differences caused by equipment defects or external interference.

[0048] In one embodiment of the present invention, the adjusting of the width of the temporary fixed channel formed by the flap in the cooling bed input roller conveyor comprises:

[0049] Increase the width of the cooling bed input roller at the cover flap. The width of the temporary fixed channel formed in the cooling bed input roller at the cover flap is 120mm.

[0050] In this embodiment, the flap at the skirt of the cooling bed input roller is used to adjust the braking distance of the straight bars when they are placed on the cooling bed, which determines whether the straight bars can be placed on the cooling bed normally. The intervention of the flap can form a temporary fixed channel for transporting straight bars in the cooling bed input roller. Before the improvement, the width of the temporary fixed channel formed by the flap in the cooling bed input roller was only about 70 mm, while the width of the transported straight bars was close to 60 mm. Since the width of the temporary fixed transport channel is too narrow, the straight bars near the edge of the temporary fixed transport channel experience excessive speed reduction, which aggravates the speed difference between the straight bars. If the edge bars are greatly decelerated due to friction resistance, while the middle bars maintain high speed, a speed gradient will be formed between adjacent bars. The high-speed bars push the low-speed bars, resulting in local accumulation, and the low-speed bars hinder the high-speed bars, causing tensile deformation. The superposition of the two forms periodic wave-like fluctuations, namely the wave-beating phenomenon. In this way, the cover flap method is improved. After the improvement, the width of the temporary fixed channel formed by the cover flap in the cooling bed input roller reaches 120mm. The width of the temporary fixed channel is increased to 120mm, and the gap between the edge scale and the inner wall of the flap is enlarged, which can reduce contact, reduce friction resistance, and reduce the speed attenuation of the edge scale, so that the speeds of the four scales tend to be consistent, reducing the excessive speed reduction phenomenon of the straight scale near the edge of the temporary fixed transport channel, and avoiding the problem of straight scales hitting waves on the cooling bed input roller.

[0051] In one embodiment of the present invention, the method of changing the fastening structure of the rollers of the cooling bed input roller table includes:

[0052] The fastening structure includes 8 to 12 symmetrically distributed bolt holes, and each roller is fixed to the roller frame by at least two groups of bolts, each group including 2 to 4 bolts.

[0053] In this embodiment, the rollers of the cooling bed input roller and the motor that provides power are an integrated structure, and are fastened to the roller frame of the cooling bed input roller by bolts. There are only 4 fastening bolt holes on the roller frame of the cooling bed input roller, which are prone to slippage during repeated use. The withdrawal of the rollers of the cooling bed input roller causes the finished product to be unable to be normally loaded onto the cooling bed, resulting in waves in the cooling bed input roller. In order to avoid this problem as much as possible, the number of fastening bolt holes is increased from 4 to 8, and the bolt holes are symmetrically distributed on the roller frame to ensure uniform force on the rollers and avoid local bolt loosening or breakage due to unilateral stress concentration. When slippage occurs in the fastening bolt holes of a certain area, other fastening bolt holes without slippage can be replaced for tightening. This can avoid the problem of waves in the finished product caused by the withdrawal of the rollers of the cooling bed input roller.

[0054] Because the Ø12mm hot-rolled ribbed steel bars produced by four-cutting are transported on the cooling bed input roller, the temperature of the finished product rolled out of the middle piece is generally higher than that of the finished products rolled out of the pieces on the sides due to the difference in their positions. If the starting rolling temperature is too high and the temperature difference between the middle and the finished products on the sides is too large, the cooling bed temperature on the bars will fluctuate greatly, causing the bars to arch on the cooling bed and become bent. In addition, the position where the straightening plates on the cooling bed rest against the bars is not level, and the elevation of the moving racks on the cooling bed that transport the bars is not consistent. This can also cause misalignment between the straightening plates and the moving racks. This can also cause the bars docked at this position to arch, resulting in bent bars.

[0055] In one embodiment of the present invention, controlling the temperature gradient of the rolled piece includes:

[0056] The initial rolling temperature of the rolled product is controlled at 1030°C to 1050°C, and a set of cooling devices for cooling each finished product separately is added to the post-rolling cooling pipe. The cooling device can adjust the cooling water volume for each finished product individually, reducing the temperature difference between the intermediate finished product and the finished products on both sides. Furthermore, infrared thermometers are installed at the inlet and outlet of the cooling bed to monitor the scale temperature in real time. The cooling device is connected to the thermometer signal and dynamically adjusts the cooling water volume based on the temperature data.

[0057] In this embodiment, when the temperature of the upper cooling bed for the Ø12mm hot-rolled ribbed steel bar is stabilized at 960℃~1040℃, the upper cooling bed will not have the problem of arching due to temperature fluctuations. Therefore, the starting rolling temperature of the steel billet used during rolling must be controlled between 1030℃~1050℃. At the same time, a set of cooling devices for cooling each finished product separately is added to the post-rolling cooling pipe. The coolant used in this device is water, and the amount of cooling water for each finished product can be adjusted separately to reduce the temperature difference between the middle finished product and the finished products on both sides. By differentiating the cooling rates, the temperature drop curves of the middle and two-side finished products tend to be consistent. An infrared thermometer is installed at the outlet of the post-rolling cooling pipe to monitor the temperature of each finished product in real time. The data is fed back to the PLC control system to dynamically adjust the amount of cooling water to achieve closed-loop control.

[0058] Furthermore, the installation accuracy adjustment of the cooling bed straightening plate and the movable rack includes:

[0059] When the straightening plates are installed, the multiple straightening positions between the straightening plates are calibrated by a laser positioning system, and the centers of the same straightening positions of the straightening plates are all on a straight line.

[0060] 200 cooling straightening plates are installed next to the cooling bed entrance skirt to prevent the upper cooling bed's ruler from bending due to inconsistent cooling speeds in different parts. Before the improvement, after the cooling bed straightening plates were installed, the connection and alignment between the straightening plates was achieved through visual observation, which would cause misalignment between the straightening plates at the same straightening center position. It is precisely because of this problem that the ruler of the upper cooling bed resting on the cooling bed straightening plates will directly arch. In order to avoid this problem, when replacing and installing the cooling bed straightening plates, the straightening position of the rulers resting between the straightening plates must be determined by pulling the center line to ensure that the centers of the same straightening position of each straightening plate are in a straight line without misalignment, thereby avoiding the arching of the ruler resting on the cooling bed straightening plates due to the misalignment of the straightening plates.

[0061] Finally, the installation accuracy adjustment of the cooling bed straightening plate and the movable rack also includes:

[0062] An up and down position fine-tuning device is added to the movable rack mounting base in each area, and the up and down position fine-tuning device adjusts the elevation of the movable rack during the production process.

[0063] In this embodiment, the scales on the cooling bed are normally transported on the cooling bed by the moving racks. The installation and commissioning of the moving racks is divided into zones. Consequently, during normal production, due to factors such as wear on the moving racks and temperature differences between different parts of the scale, the elevation of the moving racks resting on the scales may be inconsistent. Some areas may be higher, while others may be lower, leading to misalignment between the moving racks. Since the elevation of the moving racks cannot be adjusted during production, the result is that when hot scales are transported by the moving racks on the cooling bed, the elevation of the moving racks in certain areas may be inconsistent. This can cause the scales in these areas to bulge. To address this issue, a vertical fine-tuning device has been added to the mounting base of the moving racks in each zone. This device allows for adjustment of the elevation of the moving racks during normal production. If a certain part of the scale is bulging, the elevation of the moving rack in that area can be adjusted to bring the elevations of the moving racks resting on the scales in that area into a consistent state, thus resolving the bulging issue on the cooling bed.

[0064] Example 1:

[0065] Straight Ø12mm hot-rolled ribbed steel bars are produced using a four-slit rolling process. Prior to the improvements, the inner diameters of the pre-slit hole and the two middle pieces (the pre-slit hole) and the side pieces (the pre-slit hole) were designed to be the same: 7.5mm and 7mm, respectively. Under this design, the finished products, produced with the pre-slit middle hole, were transported faster on the cooling bed input roller conveyor than those produced with the pre-slit side holes. This speed difference between the four finished products during transport could easily cause the finished products to wave on the cooling bed input roller conveyor, resulting in curved steel. To address this issue, the pre-slit and slit hole profiles were improved. After the improvements, the inner diameter of the pre-slit middle hole was changed to 6.2mm, while the inner diameters of the side holes remained at 7.5mm. The inner diameter of the slit middle hole was changed to 6.9mm, while the inner diameters of the side holes remained at 7.0mm. The speed of the four finished products produced by this pass is basically the same on the cooling bed input roller. Therefore, the problem of the finished products causing waves on the cooling bed input roller caused by the multiple lengths of the finished products is solved.

[0066] Speed ​​differences still exist among the various finished Ø12mm hot-rolled ribbed rebars produced using the four-slit rolling process. The finished products are transported to the 3# shear without a conveyor roller, relying on their own speed. This process results in a sharp drop in the speed of the finished products, further exacerbating the speed differences. The flaps at the cooling bed input roller skirt adjust the braking distance for the bars before they are loaded onto the cooling bed, determining whether they can properly load onto the bed. The flaps create a temporary fixed channel within the cooling bed input roller for transporting the bars. Before the improvement, the temporary fixed channel created by the flaps was only approximately 70mm wide, while the bars being transported were nearly 60mm wide. Due to the narrowness of the temporary fixed channel, the bars near the edge of the channel experienced excessive speed reduction, exacerbating the speed differences among the bars. In addition, the rollers of the cooling bed input roller and the motor that provides power are an integrated structure and are fastened to the cooling bed input roller frame by bolts. There are only four fastening bolt holes on the cooling bed input roller frame, which are prone to slippage during repeated use, causing the cooling bed input roller to exit and the finished product length to be unable to be properly loaded onto the cooling bed. These problems can also cause the finished product length to have waves on the cooling bed input roller, causing the length to become bent steel. Therefore, three sets of accelerated conveying rollers were added between the empty guide trough where the finished products normally gather and the 3# length flying shear. This can avoid excessive deceleration of the finished products during this transportation process. At the same time, the cover flap method was improved. After the improvement, the width of the temporary fixed channel formed by the cover flap in the cooling bed input roller can reach 120mm, so that the straight length near the edge of the temporary fixed conveying channel will not experience excessive deceleration. In addition, in order to avoid the problem that the finished product cannot be put on the cooling bed due to the roller of the cooling bed input roller being out of the way, the number of fastening bolt holes has been increased from 4 to 8. When the fastening bolt hole of a certain part is stripped, the fastening bolt hole without stripping can be replaced for fastening. Through this improvement, the problem of the finished product being wavy on the cooling bed input roller caused by the above reasons has been solved.

[0067] When the Ø12mm hot-rolled ribbed steel bars produced by the four-cutting process are transported on the cooling bed input roller table, due to the difference in their positions, the temperature of the finished products rolled out of the middle rolled pieces is generally higher than that of the finished products rolled out of the rolled pieces on the two sides. If the starting rolling temperature is too high and the temperature difference between the middle and the two sides is too large, the temperature of the finished products on the upper cooling bed will fluctuate too much, making it impossible to control the temperature of the upper cooling bed within the range of 960℃ to 1040℃. In addition, 200 cooling and straightening plates are installed next to the cooling bed entrance skirt to prevent the upper cooling bed's multiple lengths from bending due to inconsistent cooling rates in different parts. Before the improvement, after the straightening plates of the cooling bed were installed, the connection and alignment between the straightening plates was achieved through visual observation, which would lead to misalignment of the same straightening center position between the straightening plates. In addition, the normal scale of the cooling bed is transmitted on the cooling bed through the moving teeth of the cooling bed, and the installation and commissioning of the moving rack is divided by area. For this reason, during the normal production process, due to the influence of factors such as the wear of the moving teeth and the temperature difference of each part of the scale, the elevation of the moving rack at the scale position will be inconsistent. Some areas are higher, while some areas may be lower, resulting in misalignment between the moving racks. The emergence of these problems will cause the scale to arch in the cooling bed, causing the scale to become bent steel. Therefore, the initial rolling temperature of the steel billet must be controlled between 1030°C and 1050°C. A separate cooling device for cooling each finished product has been added to the post-rolling cooling pipe. This device uses water as a coolant, and the amount of cooling water can be adjusted individually for each finished product, thereby minimizing the temperature difference between the intermediate and adjacent finished products. This improvement ensures that the temperature of the cooling bed on the double-strength steel plate is controlled between 960°C and 1040°C. Furthermore, when replacing and installing the straightening plates on the cooling bed, the position where each straightening plate rests on the double-strength steel plate must be determined by drawing a centerline, ensuring that the centers of each straightening plate at the same straightening position are aligned and prevent misalignment. Furthermore, a vertical fine-tuning device has been added to the mounting base of the movable rack in each area. This device allows for adjustment of the movable rack's elevation during normal production. If arching occurs in a certain area of ​​the double-strength steel plate, the elevation of the movable rack in that area can be adjusted to ensure that the elevation of each movable rack resting on the double-strength steel plate is consistent. These improvements have resolved the arching problem on the cooling bed.

[0068] This method solved the problems of corrugation and camber on the cooling bed input rollers during the double-length cooling of 12mm Ø hot-rolled ribbed steel bars cut from four strips, preventing bent steel during the process. This improvement increased the yield rate of 12mm Ø hot-rolled ribbed steel bars by 0.1%. Furthermore, since this problem was resolved, time-consuming process adjustments were eliminated, resulting in an average hourly output increase of 6.2 tons / hour for 12mm Ø hot-rolled ribbed steel bars produced from the four-slit process.

[0069] In the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances.

[0070] In summary, after reading the present invention document, ordinary technicians in this field can make various other corresponding transformation schemes based on the technical solutions and technical concepts of the present invention without creative mental work, and all of them fall within the scope of protection of the present invention.

Claims

1. A method for avoiding bending of hot-rolled ribbed steel bars during four-cut rolling on a cooling bed, characterized in that: The following steps are involved: Adjust the hole parameters in the middle and on both sides of the pre-cut holes and cut holes to reduce the difference in the conveying speed of multiple lengths; Add an adjustable speed conveying roller set between the rolled product collection area and the double-length shearing equipment to suppress the decay of the finished product conveying speed; Adjust the width of the temporary fixed channel formed by the flap in the cooling bed input roller to reduce the speed reduction of the edge length; Change the fastening structure of the rollers of the cooling bed input roller table to prevent the rollers of the cooling bed input roller table from withdrawing abnormally; Control the temperature gradient of the rolled piece and reduce the temperature difference between the middle and the finished products on both sides through the cooling device; Adjust the installation accuracy of the cooling bed straightening plate and the moving rack to eliminate the multiple-length arching caused by mechanical misalignment.

2. A method for avoiding bending of hot-rolled ribbed steel bars during four-cut rolling on a cooling bed according to claim 1, characterized in that: The method of adjusting the middle and both side hole parameters of the pre-cut hole and the cut hole respectively includes: The inner diameter of the middle hole of the pre-cut hole is smaller than the inner diameters of the two side holes, and the inner diameter of the middle hole of the cut hole is smaller than the inner diameters of the two side holes. The inner diameter of the middle hole of the pre-cut hole is 6.2mm, and the inner diameters of the two side holes of the pre-cut hole are 7.5mm. The inner diameter of the middle hole of the cut hole is 6.9mm, and the inner diameters of the two side holes of the cut hole are 7.0mm.

3. The method for avoiding bending of hot-rolled ribbed steel bars during four-cut rolling on a cooling bed according to claim 2, characterized in that: The speed-adjustable conveying roller set is added between the rolled piece collection area and the double-length shearing equipment, including: The conveying roller set includes at least three sets of accelerable conveying rollers.

4. A method for avoiding bending of hot-rolled ribbed steel bars during four-cut rolling on a cooling bed according to claim 3, characterized in that: The method of adjusting the width of the temporary fixed channel formed by the flap in the cooling bed input roller conveyor includes: Increase the width of the cooling bed input roller at the cover flap. The width of the temporary fixed channel formed in the cooling bed input roller at the cover flap is 120mm.

5. A method for avoiding bending of hot-rolled ribbed steel bars during four-cut rolling on a cooling bed according to claim 4, characterized in that: The method of changing the fastening structure of the rollers of the cooling bed input roller table includes: The fastening structure includes 8 to 12 symmetrically distributed bolt holes, and each roller is fixed to the roller frame by at least two groups of bolts, each group including 2 to 4 bolts.

6. The method for avoiding bending of hot-rolled ribbed steel bars during four-cut rolling on a cooling bed according to claim 1, characterized in that: The controlling of the temperature gradient of the rolled piece comprises: The starting rolling temperature of the rolled piece is controlled at 1030°C to 1050°C, and a group of cooling devices for cooling each finished product separately is added to the cooling pipe after rolling. The cooling device can adjust the cooling water volume of each finished product separately to reduce the temperature difference between the middle finished product and the finished products on both sides.

7. A method for avoiding bending of hot-rolled ribbed steel bars during four-cut rolling on a cooling bed according to claim 6, characterized in that: The installation precision adjustment of the cooling bed straightening plate and the movable rack includes: When the straightening plates are installed, the multiple straightening positions between the straightening plates are calibrated by a laser positioning system, and the centers of the same straightening positions of the straightening plates are all on a straight line.

8. The method for avoiding bending of hot-rolled ribbed steel bars during four-slit rolling on a cooling bed according to claim 7, characterized in that: The installation accuracy adjustment of the cooling bed straightening plate and the movable rack also includes: An up and down position fine-tuning device is added to the movable rack mounting base in each area, and the up and down position fine-tuning device adjusts the elevation of the movable rack during the production process.

9. The method for avoiding bending of hot-rolled ribbed steel bars during four-slit rolling on a cooling bed according to claim 3, characterized in that: The method of adding a speed-adjustable conveying roller set between the rolled piece collection area and the double-length shearing device also includes: Speed ​​sensors are installed at both ends of the cooling bed input roller. The speed sensors monitor the multiple-length conveying speed in real time. The speed sensors feed back the finished product conveying speed data to the PLC control system. The PLC control system dynamically adjusts the speed of the conveying roller according to the speed difference.

10. The method for avoiding bending of hot-rolled ribbed steel bars during four-slit rolling on a cooling bed according to claim 6, characterized in that: The controlling of the temperature gradient of the rolled piece further comprises: Infrared thermometers are installed at the entrance and exit of the cooling bed to monitor the scale temperature in real time. The cooling device is connected to the thermometer signal and dynamically adjusts the cooling water volume according to the temperature data.

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