A method for controlling tapping rhythm of a steel rolling bar production line

Abstract

The present application belongs to the technical field of bar rolling, and specifically discloses a method for controlling the tapping rhythm of a steel bar production line, which comprises the following steps: detecting the tapping signal in real time through a first heat detector and a second heat detector, realizing the rapid tapping operation from the furnace cantilever roller way to the first furnace roller way stage, realizing the tapping effect of the head-to-tail connection of the two adjacent billets, shortening the time of the no-steel gap, and improving the steel passing amount; adjusting the speed of a first rolling mill and a second rolling mill, better realizing the rolling rhythm control process under the variable speed of the double-rolling mill equipment, sequentially reducing the speed of the first rolling mill and the second rolling mill, pulling apart the distance between the previous billet and the next billet, prolonging the steel passing time, ensuring that the billet interval under the tapping rhythm can meet the normal operation of the flying shear, reasonably adjusting the speed reduction and the speed increase of the first rolling mill and the second rolling mill, slowing down the damage degree of the power device of the motor and the speed reducer in the rolling mill equipment, and indirectly prolonging the service life of the rolling mill equipment.

Description

Technical Field

[0001] This invention relates to the field of bar rolling technology, and more specifically to a method for controlling the tapping rhythm of a steel bar production line. Background Technology

[0002] Currently, steel tapping in the heating furnace is done manually by operators. During the tapping process of the cantilever roller conveyor and the walking beam, the production rhythm can only be controlled by human judgment. Usually, the control range for adjacent steel billets passing through the furnace is within 4-5 seconds. At the same time, continuous tapping of steel billets cannot be achieved, which limits production efficiency.

[0003] In traditional production processes, when two consecutive steel billets transition from the furnace cantilever roller conveyor to the furnace roller conveyor and then enter the first stand of the roughing mill, a minimum 2-second time interval must be maintained between adjacent billets to ensure the flying shear can perform its shearing operation normally and ensure smooth production. To maintain this 2-second interval, under traditional process control, the two consecutive billets undergo approximately a 40% speed reduction and acceleration as they pass through the first stand of the mill, maintaining a distance to allow the flying shear to perform its shearing action smoothly. However, this speed control results in excessive speed reduction and acceleration of the motor and reducer in the first stand of the mill, increasing the equipment load and potentially causing damage during long-term operation.

[0004] Therefore, due to the unreasonable control of the steel output rhythm, the first mill frequently and significantly reduced and increased its speed. Over a long period of time, this resulted in significant wear and tear on the mill equipment, thereby reducing its service life and shortening the maintenance cycle. Summary of the Invention

[0005] The purpose of this invention is to provide a method for controlling the tapping rhythm of a steel bar production line, so as to solve the problem that the existing steel tapping rhythm control is unreasonable, resulting in large wear and tear on the rolling mill equipment.

[0006] To achieve the above objectives, the basic solution provided by this invention includes the following steel tapping steps:

[0007] S1: The first steel billet is placed on the cantilever roller conveyor of the furnace by the walking beam of the heating furnace. Under the manual operation control of the operator, the cantilever roller conveyor of the furnace is operated, and the first steel billet is discharged from the cantilever roller conveyor of the heating furnace. Then it enters the first discharge roller conveyor, the second discharge roller conveyor and the rolling mill equipment in sequence. The rolling mill equipment includes the first rolling mill, the second rolling mill and the third rolling mill.

[0008] S2: When the first billet leaves the furnace cantilever roller conveyor, the first heat detection device sends the detected steel throwing signal at the furnace outlet to the PLC controller. The PLC controller controls the walking beam of the furnace to perform the steel shaking operation of the second billet, placing the second billet on the furnace cantilever roller conveyor to wait for steel to be discharged.

[0009] S3: When the first steel billet leaves the second hot inspection device and reaches the first rolling mill to achieve steel biting, the second hot inspection device sends the detected steel throwing signal of the first steel billet to the PLC controller. The PLC controller controls the operation of the furnace cantilever roller conveyor to start the second steel billet from being discharged to the first furnace roller conveyor.

[0010] S4: When the second billet runs to the second exit roller and leaves the second heat detection device, the second heat detection device detects the billet's ejection signal and sends it to the PLC controller. The PLC controller controls the speed of the first rolling mill to decrease from the original speed V to V1.

[0011] S5: When the first billet leaves the second rolling mill, the second hot detection device detects the steel ejection signal at the second rolling mill and sends it to the PLC controller. The PLC controller controls the speed of the second rolling mill to decrease from the original speed V to V1.

[0012] S6: When the first billet leaves the third rolling mill, the second hot detection device detects the steel ejection signal at the third rolling mill and sends it to the PLC controller. The PLC controller controls the speed of the first and second rolling mills to increase respectively, and restores the speed from V1 to the original speed V.

[0013] The principle and beneficial effects of this invention are as follows: This invention uses a first and a second heat detection device to detect the steel ejection signal in real time, enabling rapid steel loading from the furnace cantilever roller table to the first furnace exit roller table stage. This achieves the effect of connecting two adjacent steel billets end to end, shortening the time without steel gap, increasing the steel throughput, and thus improving production efficiency. By adjusting the speed of the first and second rolling mills, the rolling rhythm control process is better realized under the speed change of the dual rolling mill equipment. By using the sequential speed reduction operation of the first and second rolling mills, the distance between the previous and subsequent steel billets is increased, extending the steel throughput time. This ensures that the steel billet interval under this steel output rhythm can meet the normal operation of the flying shear. By reasonably adjusting the speed reduction and increase of the first and second rolling mills, the damage to the power devices of the motors and reducers in the rolling mill equipment is reduced, indirectly extending the service life of the rolling mill equipment.

[0014] Option 2, which is a preferred option of the basic option, involves the first steel billet passing through the first, second, and third rolling mills at the original speed V in step S3.

[0015] Option 3, which is a preferred option of the basic option, involves disconnecting the cascaded signal between the second rolling mill and the first rolling mill in step S5.

[0016] Option 4, which is a preferred option of Option 2, involves speed V1 being 15%-17% lower than the original speed V in steps S4-S6.

[0017] Option 5, which is the preferred option of Option 3, involves calculating the deceleration time interval during the first rolling mill deceleration process in step S4 using the formula T = S / V2, where S is the distance between the second heat inspection device and the first rolling mill, and V2 is the speed of the second exit roller table.

[0018] Option 6, which is a preferred option of Option 5, involves the first mill speed-up and the second mill speed-up occurring synchronously in step S6.

[0019] Option 7, which is the preferred option of the basic option, if the length of the billet is greater than S, the first hot inspection device sends the billet's ejection signal to the PLC controller, and the PLC controller controls the speed of the first rolling mill to decrease from V to V1.

[0020] Option 8, which is a preferred option of Option 6, establishes a cascade signal between the second rolling mill and the first rolling mill in step S6. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a method for controlling the steel output rhythm of a steel bar production line according to the present invention. Detailed Implementation

[0022] The present invention will be further described in detail below through specific embodiments:

[0023] The reference numerals in the accompanying drawings include: 1. Exit cantilever roller conveyor; 2. First exit roller conveyor; 3. Second exit roller conveyor; 4. First heat inspection device; 5. Second heat inspection device; 6. First rolling mill; 7. Second rolling mill; 8. Third rolling mill; 9. Flying shear.

[0024] like Figure 1 The diagram illustrates a method for controlling the tapping rhythm of a steel bar production line. The method includes each steel billet, after being tapped from the heating furnace outlet, transitioning between a first and second tapping roller conveyor, and preparing to enter the rolling mill for a bite operation. The rolling mill includes a first mill, a second mill, and a third mill. The specific tapping steps are as follows:

[0025] During normal steel tapping, if the first rolling mill or the first hot inspection device does not show a steel biting signal, the cantilever tapping roller conveyor, the first tapping roller conveyor, and the second tapping roller conveyor are all started and run at high speed by manual or electric control to prepare for the billet shaking and tapping operations.

[0026] First, the first billet is manually tapped. The operator manually controls the walking beam in the furnace. After the walking beam rises 105mm, it moves 20mm towards the first tapping roller. The walking beam then moves the first billet from the furnace inlet cantilever roller to the tapping roller. The furnace door at the furnace outlet is manually opened, and the control valve at the door is used to fully open the door, allowing the billet to be tapped smoothly and enter the first tapping roller. Once the first billet has completely left the first heat detection device, the device detects billet being tapped at the furnace outlet. The first heat detection device is connected to the furnace door at the furnace outlet and transmits the billet tapping signal to the PLC controller. The PLC controller then controls the walking beam in the furnace to move the next billet from the furnace inlet cantilever roller to the tapping roller, ready for tapping.

[0027] The first steel billet is transported sequentially on the first and second exit roller conveyors. It is then conveyed to the entrance of the first rolling mill. When the first billet has fully entered the mill, a second thermal detection device detects that the billet has been ejected. This device is connected to the second exit roller conveyor and positioned near its entrance. The second thermal detection device transmits the ejection signal to a PLC controller, which then controls the operation of the furnace's exit cantilever roller conveyor to eject the second billet placed on it. At this time, the first, second, and third rolling mills all maintain their original speed V. Here, "the first billet being ejected" means that the billet has completely passed the second thermal detection device, and its end has left the detection area.

[0028] Subsequently, after the second billet exits the furnace, it enters the first exit roller conveyor and runs sequentially through the first and second exit roller conveyors. When the second heat detection device detects that the second billet has been ejected, a third billet is placed on the furnace exit cantilever roller conveyor waiting to be ejected. At the same time, the second billet has already been bitten into the first rolling mill. The ejection signal of the second billet is sent to the PLC controller. The PLC controller controls the operation of the furnace exit cantilever roller conveyor and performs the ejection operation on the third billet. The PLC controller also controls the speed of the first rolling mill to be reduced from the original speed V by 15%-17% to V1. This process is the first speed reduction operation in the steel ejection process.

[0029] After the cantilever roller conveyor detects the billet signal from the heating furnace, the speed of the second exit roller conveyor is set to V2, and the distance between the second heat detection device and the first rolling mill is S. According to the calculation formula T = S / V, where T is the speed reduction interval, the minimum time interval that adjacent billets need to meet when the first rolling mill starts to reduce speed is obtained based on this speed reduction interval. This speed reduction interval is used to meet the rolling requirements of billets with a length of less than 12m.

[0030] The mode of reducing the speed of the first rolling mill based on the steel ejection signal detected by the second heat detection device is applicable when the length of the billet is less than or equal to the distance between the second heat detection device and the first rolling mill (in this case, the billet length is usually less than 12m). When the length of the billet is greater than the distance between the second heat detection device and the first rolling mill (in this case, the billet length is usually greater than 12m), in order to ensure that the first rolling mill can reduce its speed in advance, the speed reduction mode is to send a steel ejection signal when the first heat detection device detects steel ejection at that point. The PLC controller controls the first rolling mill to start reducing its speed according to the steel ejection signal. In this way, when the longer billet reaches the first rolling mill and bites, the speed of the first rolling mill can also be reduced to V1.

[0031] Immediately after the second hot inspection device detects the ejection signal of the second billet 2 seconds later, the speed of the first exit roller table is also reduced to keep the speed of the first exit roller table the same as that of the first rolling mill, so as to avoid severe wear of the first exit roller table under long-term high-speed operation. After the first speed reduction operation, the first billet is now in the second rolling mill, while the second billet is between the second exit roller table and the first rolling mill. The running speed of the second rolling mill is V, and the running speed of the first rolling mill is V1. Since V1 < V, the distance between the second billet and the first billet gradually increases.

[0032] When the second heat detection device detects that the first billet has been ejected at the exit of the second rolling mill, the ejection signal is sent to the PLC controller. The PLC controller then reduces the speed of the second rolling mill from its original speed V by 15%-17% to V1. This is the second speed reduction operation during the tapping process. The first and second rolling mills are not in a cascaded signal connection state during this second speed reduction; therefore, the speed reduction operation of the second rolling mill does not affect the operation of the first rolling mill. After the second speed reduction operation, the second billet runs between the first and second rolling mills and gradually enters the second rolling mill. The second billet moves at a speed of V1 in both the first and second rolling mills. At this point, the first billet is already in the third rolling mill, and the distance between the first and second billets further increases.

[0033] When the second heat detection device detects that the first billet is ejected at the exit of the third rolling mill, it sends the ejection signal of the first billet at the exit of the third rolling mill to the PLC controller. At this time, after the second billet bites into the second rolling mill, there is a 2-second delay. After 2 seconds, the PLC controller controls the first and second rolling mills to simultaneously increase their speeds, increasing their operating speeds from speed V1 by 15%-17% to the original speed V. Since the second billet has already created distance between it and the first billet, to avoid the phenomenon of billet pulling when the rolling mills are not running at the same speed, the speeds of the first and second rolling mills need to be restored to their original speeds and kept consistent with the speed of the third rolling mill. During this speed-up process, the second billet must complete the speed-up before being bitten by the third rolling mill. When the third rolling mill completes biting the second billet, a cascaded signal connection is established between the first and second rolling mills.

[0034] In actual steel tapping practice, the rate of decrease has different impacts on equipment operation.

[0035] Table 1. Impact of Different Speed ​​Variation Ranges of the First and Second Rolling Mills on Equipment Operation

[0036]

[0037] As shown in Table 1, when the speed variation of the first and second rolling mills is 17%-30%, the power equipment of the first and second rolling mills, namely the motors and reducers, is noisy during operation. The motors are under heavy load during operation, which directly results in greater wear and tear on the motors and reducers of the first and second rolling mills. Ultimately, this leads to a reduction in the lifespan of the motors and reducers of the first and second rolling mills, thus reducing their maintenance cycle.

[0038] When the speed variation range of the first and second rolling mills is 15%-17%, the power equipment of the first and second rolling mills, namely the motors and reducers, will not make any abnormal noises during operation. Therefore, the service life of the motors and reducers will not be affected by the range of frequent speed changes. Under this speed variation range, the interval between adjacent steel billets can ensure the normal shearing action of the flying shear.

[0039] When the speed variation of the first and second rolling mills is less than 15%, the power equipment of the first and second rolling mills, namely the motors and reducers, will not make any abnormal noises during operation due to the small speed variation. However, this will not create enough distance between adjacent steel billets. When adjacent steel billets pass under the flying shear, the flying shear cannot determine that it is passing two steel billets, and thus only performs the shearing action when the first steel billet passes. Therefore, under this speed variation, the interval between adjacent steel billets cannot guarantee the normal shearing action of the flying shear.

[0040] In summary, the optimal adjustment range for the first and second rolling mills when adjusting deceleration or acceleration is 15%-17%. This range will not damage the power equipment motor and reducer, nor will it affect the normal shearing operation of the flying shear after the third rolling mill.

[0041] Based on the three-stage operation of the first and second rolling mills described above, which involves "deceleration followed by acceleration," the two deceleration operations and one acceleration operation in this operation are considered as one cycle. This cycle is performed once for every two steel billets, i.e., the first and second billets constitute one cycle, the third and fourth billets constitute one cycle, and so on. The two adjacent steel billets are fed into the furnace quickly with their heads and tails touching in the first and second exit roller conveyors. These two steel billets maintain the required distance between adjacent steel billets through repeated deceleration and acceleration in the first and second rolling mills, thereby ensuring the normal operation of the flying shear.

[0042] In practical operation, the steel-passing status is judged according to the motor current of the first and second rolling mills. When the motor current is above 60%, it is determined that a steel billet has passed through the first or second rolling mill; conversely, when the motor current is below 60%, it is determined that no steel billet has passed through the first or second rolling mill. At this time, if the motor current is below 60% for 2 seconds, it can be inferred that the first steel billet passed through the first or second rolling mill, and 2 seconds later, the second steel billet passed through the first rolling mill. That is, the steel-passing time interval of 2 seconds is the minimum steel-passing time interval. In order to ensure that the looper of the flying shear and the subsequent finishing mill can operate normally, the time interval between two adjacent steel billets is at least 2 seconds. According to the above-mentioned operation process of the first and second rolling mills of "decelerating first and then accelerating", it can be guaranteed that the time interval between adjacent steel billets is greater than or equal to 2 seconds. The operator can monitor and verify this at any time through the motor current.

[0043] The method of this invention successfully achieves automatic steel rolling and unloading. The steel throwing signal detected by the first and second heat detection devices is sent to the PLC controller, realizing rapid steel loading operation from the furnace cantilever roller table to the first furnace roller table stage. This achieves the effect of unloading two adjacent steel billets end to end, shortening the time without steel gap, increasing the steel throughput and thus improving production efficiency. By adjusting the speed of the first and second rolling mills, the rolling rhythm control process is better realized under the speed change of the dual rolling mill equipment. By using the first and second rolling mills to reduce speed sequentially, the distance between the previous and subsequent steel billets is increased, extending the steel throughput time. This ensures that the steel billet interval under this steel loading rhythm can meet the normal operation of the flying shear. Reasonably adjusting the speed reduction and increase of the first and second rolling mills reduces the damage to the power devices of the motors and reducers in the rolling mill equipment, indirectly extending the service life of the rolling mill equipment.

[0044] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for controlling the tapping rhythm of a steel bar production line, characterized in that, Specifically, the steel tapping steps include the following: S1: The first steel billet is placed on the cantilever roller conveyor of the furnace by the walking beam of the heating furnace. Under the manual operation control of the operator, the cantilever roller conveyor of the furnace is operated, and the first steel billet is discharged from the cantilever roller conveyor of the heating furnace. Then it enters the first discharge roller conveyor, the second discharge roller conveyor and the rolling mill equipment in sequence. The rolling mill equipment includes the first rolling mill, the second rolling mill and the third rolling mill. S2: When the first billet leaves the furnace cantilever roller conveyor, the first heat detection device sends the detected steel throwing signal at the furnace outlet to the PLC controller. The PLC controller controls the walking beam of the furnace to perform the steel shaking operation of the second billet, placing the second billet on the furnace cantilever roller conveyor to wait for steel to be discharged. S3: When the first steel billet leaves the second hot inspection device and reaches the first rolling mill to achieve steel biting, the second hot inspection device sends the detected steel throwing signal of the first steel billet to the PLC controller. The PLC controller controls the operation of the furnace cantilever roller conveyor to start the second steel billet from being discharged to the first furnace roller conveyor. S4: When the second billet runs to the second exit roller and leaves the second heat detection device, the second heat detection device detects the billet's ejection signal and sends it to the PLC controller. The PLC controller controls the speed of the first rolling mill to decrease from the original speed V to V1. S5: When the first billet leaves the second rolling mill, the second hot detection device detects the steel ejection signal at the second rolling mill and sends it to the PLC controller. The PLC controller controls the speed of the second rolling mill to decrease from the original speed V to V1. S6: When the first billet leaves the third rolling mill, the second thermal detection device detects the billet ejection signal at the third rolling mill and sends it to the PLC controller. The PLC controller controls the speed of the first and second rolling mills to increase from V1 back to the original speed V. The billet passing status is judged according to the motor current of the first and second rolling mills. When the motor current is above 60%, it is judged that a billet has passed on the first or second rolling mill. Conversely, when the motor current is below 60%, it is judged that no billet has passed on the first or second rolling mill. When the motor current is below 60% for 2 seconds, it is estimated that the second billet passed on the first rolling mill 2 seconds after the first billet passed on the first or second rolling mill. In steps S4-S6, the speed V1 is 15%-17% lower than the original speed V.

2. The method for controlling the tapping rhythm of a steel bar production line according to claim 1, characterized in that, In step S3, the first steel billet passes through the first rolling mill, the second rolling mill, and the third rolling mill at the original speed V.

3. The method for controlling the tapping rhythm of a steel bar production line according to claim 1, characterized in that, In step S5, the second rolling mill disconnects from the first rolling mill via a cascaded connection signal.

4. The method for controlling the tapping rhythm of a steel bar production line according to claim 3, characterized in that, During the deceleration process of the first rolling mill in step S4, the deceleration time interval is calculated according to the formula T=S / V2, where S is the distance between the second heat detection device and the first rolling mill, and V2 is the speed of the second exit roller table.

5. The method for controlling the tapping rhythm of a steel bar production line according to claim 4, characterized in that, In step S6, the speed increase of the first rolling mill is synchronized with that of the second rolling mill.

6. The method for controlling the tapping rhythm of a steel bar production line according to claim 1, characterized in that, If the billet length is greater than S, where S is the distance between the second heat detection device and the first rolling mill, the first heat detection device sends the billet ejection signal to the PLC controller, and the PLC controller controls the speed of the first rolling mill to decrease from V to V1.

7. The method for controlling the tapping rhythm of a steel bar production line according to claim 5, characterized in that, In step S6, a cascade signal is established between the second rolling mill and the first rolling mill.

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