Rolled piece transmission automatic positioning method based on image recognition length measurement technology

Abstract

The invention discloses a rolled piece transmission automatic positioning method based on an image recognition and length measurement technology, and the method comprises the steps: obtaining the length information of a rolled piece in a conveying process in real time through the image recognition and length measurement technology of a plurality of cameras, calculating the sawing length through the combination of the temperature of the rolled piece, the multiple length number and the length of a finished product, and achieving the precise control of a sawing position. The method comprises the five steps of image recognition length measurement, saw cutting length calculation, conveying roller way multi-stage speed reduction control, tailing discarding speed automatic selection and positioning compensation. In the image recognition length measurement stage, whole-course non-blind-area measurement of a rolled piece is achieved through multi-camera overlapping view; in the saw cutting length calculation stage, the thermal expansion and cold contraction effects at different temperatures are considered, and the saw cutting lengths of different cutting times are calculated; in the transmission control stage, a three-stage speed reduction and slow parking mode is adopted, and positioning errors caused by inertial sliding are avoided. Through the combination of image recognition and intelligent control, the rolled piece positioning precision and the production efficiency are improved.

Description

Technical Field

[0001] This invention belongs to the field of electrical automatic control technology. Specifically, this invention relates to an automatic positioning method for rolling mill transfer based on image recognition length measurement technology. Background Technology

[0002] In the field of long product rolling production, especially in the processing of profiles such as H-beams, the fixed-length sawing of rolled products is a crucial process to ensure product dimensional accuracy and suitability for subsequent processing. Currently, the mainstream H-beam sawing operations in the industry generally rely on a collaborative working mode of fixed saws and fixed-length saws. The specific operation process is as follows:

[0003] First, based on the required finished length of the rolled piece, the operator must move the length-setting machine to a preset position matching the target length using automatic control or manual adjustment. The core functional component of this length-setting machine is the buffer baffle, whose positional accuracy directly determines the length deviation of the rolled piece after sawing. Subsequently, the H-beam rolled piece, formed through the rolling process, is conveyed towards the fixed saw at a set speed via a conveyor roller conveyor. When the front end of the rolled piece contacts and impacts the buffer baffle of the length-setting machine, the buffer baffle triggers a position signal, and the conveyor roller conveyor immediately stops running. At this point, the rolled piece is exactly in the sawing working area of ​​the fixed saw, and finally, the fixed saw performs the sawing action to complete the length-setting processing of a single rolled piece.

[0004] However, the aforementioned traditional technical solutions have significant limitations in practical production applications. Specifically, the sawing length of the rolled steel is entirely limited by the physical movement range of the sizing machine. Since the length of the sizing machine's moving track and the stroke of its drive mechanism both have fixed design limits, when the length of the rolled steel produced exceeds the maximum operating range of the sizing machine, the existing collaborative mode between the fixed saw and the sizing machine cannot effectively position and saw the rolled steel. This technical bottleneck not only restricts the sizing diversity of H-beam products, making it impossible to accept some long-specification orders, but may also force companies to meet demand by sawing and then splicing sections. This increases production processes and costs, and makes it difficult to guarantee the overall precision and mechanical properties of the spliced ​​product, severely restricting the production line's flexibility and market competitiveness.

[0005] In addition, in the traditional mode, the position adjustment of the length-setting machine relies on manual intervention or preset programs. When switching production for rolled parts of different length specifications, the position of the length-setting machine needs to be readjusted and the accuracy calibrated. The operation process is cumbersome and time-consuming. It is easy for human operation errors or equipment debugging deviations to cause unqualified sawing lengths, which further reduces production efficiency and product qualification rate.

[0006] This paper presents an automatic positioning method for rolled workpiece transport based on image recognition length measurement technology, specifically addressing how to achieve accurate positioning and sawing control of the rolled workpiece to improve production efficiency. Summary of the Invention

[0007] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides an automatic positioning method for rolled piece transport based on image recognition length measurement technology, with the purpose of achieving accurate positioning and sawing control of the rolled piece, thereby improving production efficiency.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is: an automatic positioning method for rolled piece transfer based on image recognition length measurement technology, comprising the following steps:

[0009] S1. Image recognition length measurement: During the transfer of the rolled piece, multiple cameras arranged along the transfer path are used to collect images of the rolled piece, process the images and calculate the length to obtain the real-time length information of the rolled piece.

[0010] S2. Calculation of sawing length: Based on the current temperature of the rolled piece, the multiple of length and the target finished length, the sawing length L of the rolled piece is calculated according to the preset formula L = (L0 + ΔL) × N × (1 + k×T), where L0 is the target finished length, ΔL is the correction length, N is the multiple of length, T is the current temperature of the rolled piece and k is the coefficient of thermal expansion.

[0011] S3. Transmission control: With the fixed saw as the reference position, the PLC control system controls the speed of the conveyor rollers according to the length value of the rolled piece fed back by the image recognition length measurement system, so that the rolled piece runs at full speed and decelerates in multiple stages until it stops when it approaches the target position.

[0012] S4. Automatic tail-scraping speed selection: Automatically selects the corresponding tail-scraping speed based on the sawing length and weight per meter of the rolled piece;

[0013] S5. Positioning Compensation: By setting a positioning compensation value, the position of the deceleration point is corrected to achieve precise positioning of the workpiece at the fixed saw position.

[0014] In step S1, the fields of view of the cameras overlap to eliminate installation errors, and the overlap range of the camera fields of view is 200mm to 600mm.

[0015] The camera is installed at a height of 3 to 5 meters above the surface of the conveyor rollers and is used in conjunction with a laser light source for supplementary lighting to improve the accuracy and stability of image recognition.

[0016] In step S2, the value of the thermal expansion coefficient k ranges from (1.0 to 1.2) × 10⁻⁶. -5 Furthermore, the sawing length is calculated separately for the first and second cuts of the same rolled piece based on the real-time temperature.

[0017] Step S3 includes a three-stage deceleration process, namely:

[0018] In the first deceleration stage, when the workpiece is 7-8m away from the target position, the speed of the conveyor rollers is reduced from full speed to about 2.0-2.2m / s;

[0019] In the second deceleration stage, when the workpiece is 2 to 3 meters away from the target position, the speed of the conveyor rollers is reduced to the preset tail-throwing speed.

[0020] In the third deceleration stage, when the workpiece is 0.1 to 0.3 m away from the target position, the roller conveyor frequency converter reduces the speed of the conveyor roller to 0 in a ramp curve manner.

[0021] In step S4, the PLC control system automatically determines the tail-scraping speed based on the relationship between the sawing length of the rolled piece and its weight per meter, as follows:

[0022] When the sawing length is greater than 40m and the weight per meter is less than 130kg / m, the tail-throwing speed is 0.5~0.6m / s;

[0023] When the sawing length is greater than 40m and the weight per meter is greater than 130kg / m, the tail-throwing speed is 0.6~0.8m / s;

[0024] When the sawing length is less than 40m and the weight per meter is greater than 200kg / m, the tail throwing speed is 0.8~1.0m / s.

[0025] In step S5, the positioning compensation value is used to adjust the deceleration point position, and the positioning compensation value can be set in the range of −400mm to +400mm.

[0026] When the workpiece is positioned beyond the target position, the deceleration point position is corrected by reducing the positioning compensation value; when the workpiece is positioned below the target position, the deceleration point position is corrected by increasing the positioning compensation value, in order to compensate for the mechanical error of the roller conveyor or changes in the on-site working conditions.

[0027] The image recognition length measurement system establishes a length measurement coordinate system with a fixed saw as a reference calibration point, and transmits the length information of the rolled piece to the PLC control system in real time through the length measurement server to achieve closed-loop control.

[0028] The image recognition length measurement system includes an image acquisition module, an image processing module, a length calculation module, and a communication module. The modules communicate with each other via industrial Ethernet or fieldbus.

[0029] After the head of the rolled piece is sawn, the operator starts the image recognition length measurement system, and the PLC system simultaneously starts the pre-saw roller control program.

[0030] During the third stage of deceleration, the workpiece maintains a constant speed for 0.5 seconds to dissipate inertial energy, thereby stabilizing the final stopping position and improving positioning accuracy.

[0031] The automatic positioning method for rolled piece transport based on image recognition length measurement technology of the present invention has the following beneficial effects:

[0032] (1) It can realize the automatic transmission and positioning of the rolled piece according to the set length while the image recognition system measures the length of the rolled piece, so as to realize the accurate positioning and sawing control of the rolled piece. Compared with manual positioning, it improves production efficiency and reduces the labor intensity of operators.

[0033] (2) In areas where installation is restricted, it is a reliable alternative to traditional mechanical length cutters, reducing investment costs. Attached Figure Description

[0034] This manual includes the following figures, which illustrate the following:

[0035] Figure 1 This is a diagram showing the camera layout of the image recognition length measurement system before the hot saw cools the bed;

[0036] Figure 2 This is a configuration diagram of an image recognition length measurement system;

[0037] Figure 3 This is a diagram showing the automatic positioning speed control for rolled piece transport.

[0038] Figure 4 This is a flowchart of automatic positioning control based on image recognition length measurement technology;

[0039] Figure 5 It is a waveform diagram of the production record for the 410x179x8.8x14.4 specification;

[0040] Figure 6 It is a waveform diagram of the production record for the 327x319x16x25 specification;

[0041] The following are labeled in the diagram: 1. First camera; 2. Second camera; 3. Third camera; 4. Fourth camera; 5. Fixed saw; 6. Roller conveyor centerline; 7. Electrical cabinet; 8. Length measuring server; 9. PLC control system; 10. Transmission cabinet; 11. Laser light source; 12. Rolled workpiece. Detailed Implementation

[0042] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention, and to facilitate its implementation.

[0043] It should be noted that in the following embodiments, the terms "first", "second", "third" and "fourth" do not represent an absolute distinction in structure and / or function, nor do they represent the order of execution, but are merely for the convenience of description.

[0044] like Figures 1 to 4 As shown, this embodiment of the invention provides an automatic positioning method for rolled piece transfer based on image recognition length measurement technology, including the following steps:

[0045] S1. Image recognition length measurement: During the transfer of the rolled piece, multiple cameras arranged sequentially along the transfer path are used to collect images of the rolled piece. The images are then processed and the length is calculated to obtain the real-time length information of the rolled piece.

[0046] S2. Calculation of sawing length: Based on the current temperature of the rolled piece, the multiple of length and the target finished length, the sawing length L of the rolled piece is calculated according to the preset formula L = (L0 + ΔL) × N × (1 + k×T), where L0 is the target finished length, ΔL is the correction length, N is the multiple of length, T is the current temperature of the rolled piece and k is the coefficient of thermal expansion.

[0047] S3. Transmission control: With the fixed saw as the reference position, the PLC control system controls the speed of the conveyor rollers according to the length value of the rolled piece fed back by the image recognition length measurement system, so that the rolled piece runs at full speed and decelerates in multiple stages until it stops when it approaches the target position.

[0048] S4. Automatic tail-scraping speed selection: Automatically selects the corresponding tail-scraping speed based on the sawing length and weight per meter of the rolled piece;

[0049] S5. Positioning Compensation: By setting a positioning compensation value, the position of the deceleration point is corrected to achieve precise positioning of the workpiece at the fixed saw position.

[0050] Specifically, this invention belongs to the field of electrical automatic control. More specifically, it is a method for accurately positioning the transported object by using image recognition length measurement technology to obtain the length of the transported object, and by using program logic to determine the speed reference value of the transport roller according to the chart requirements, thereby controlling the start, operation, braking and stopping of the roller.

[0051] This invention provides an automatic positioning method for rolled piece transport based on an image recognition length measurement system. Within the camera's recognition range, the method automatically provides a reference value for the roller conveyor speed based on the length of the rolled piece recognized by the camera, and controls the start, operation, braking, and stop of the roller conveyor to achieve accurate positioning and sawing control of the rolled piece.

[0052] The main innovative points of this invention are as follows:

[0053] (1) Image recognition-based length measurement technology serves as position feedback for precise positioning of rolled pieces;

[0054] (2) Calculate the sawing length based on the temperature of the rolled piece to be sawed, the multiple of the length, and the finished product length. In particular, the sawing length will be different when the temperature of the first and second sawing cuts is different.

[0055] (3) When the rolled piece is conveyed close to the target position, a three-stage deceleration is adopted, and the traditional emergency stop is changed to a slow stop, so as to ensure the control of the rolled piece following the roller table;

[0056] (4) Automatically select the tail-throwing speed according to the rolling product and sawing length;

[0057] (5) To eliminate the impact of abnormal conditions on site and to achieve accurate positioning, a positioning compensation value is introduced.

[0058] Preferably, in step S1 above, an image recognition length measurement system is used. The image recognition length measurement system includes multiple cameras with overlapping fields of view to eliminate installation errors. The overlapping range of the camera fields of view is 200mm to 600mm.

[0059] Preferably, in step S1 above, the camera is installed at a height of 3 to 5 meters from the surface of the conveyor roller.

[0060] In embodiments of the present invention, such as Figure 1 and Figure 2 As shown, a total of four cameras are installed: a first camera, a second camera, a third camera, and a fourth camera. These cameras are arranged sequentially along the conveyor path of the rolled piece. They acquire images of the rolled piece and are supplemented with laser light to improve the accuracy and stability of image recognition. The cameras are installed at a height of 4 meters above the surface of the conveyor rollers.

[0061] In step S1 above, the rolled piece is an H-beam. Measurement primarily relies on image processing technology, which identifies the target contour in the image and calculates its length. This process includes four control parts: image acquisition, image preprocessing, target recognition, and length calculation, etc. (See...) Figure 2 Because the rolled H-beams are too long, the field of view of a single camera cannot be fully covered. Therefore, multiple cameras are needed to measure the length. Each camera captures a picture of the moving workpiece, obtaining an image of the workpiece head within its field of view. A fixed saw is used as the fixed cutting point, and image analysis is employed for measurement. The input roller conveyor speed before the H-beam cooling bed is approximately 3 m / s. The shearing length of the workpiece ranges from 30 m to 60 m. Four cameras are positioned at the fixed hot saw and the roller conveyor behind the sizing machine to ensure that the camera's field of view covers the 30 m to 60 m range without blind spots (e.g., ...). Figure 1As shown: the camera's field of view overlaps within 500mm (to eliminate errors during installation), and the camera's vertical height is approximately 4m from the front roller conveyor of the cooling bed.

[0062] In this embodiment of the invention, a laser light source is added for supplementary lighting to improve the reliability and accuracy of length measurement. During actual measurement, a fixed saw is used as a reference, and marks are made within the camera's field of view. The length measurement server transmits the measured length of the rolled piece to the PLC control system in real time. The PLC control system controls the start, operation, deceleration, and stopping of the conveyor rollers via the transmission cabinet. (See...) Figure 3 .

[0063] In this embodiment of the invention, the image recognition length measurement system establishes a length measurement coordinate system with a fixed saw as a reference calibration point, and transmits the length information of the rolled piece to the PLC control system in real time through the length measurement server, thereby achieving closed-loop control. The image recognition length measurement system includes an image acquisition module, an image processing module, a length calculation module, and a communication module. These modules communicate with each other via industrial Ethernet or fieldbus. The length calculation module is used to calculate the sawing length of the rolled piece. The image acquisition module includes a camera and a laser light source. The image processing module and the length calculation module are built into the length measurement server, which is electrically connected to the PLC control system.

[0064] Preferably, in step S2 above, the coefficient of thermal expansion k ranges from (1.0 to 1.2) × 10⁻⁶. -5 Furthermore, the sawing length is calculated separately for the first and second cuts of the same rolled piece based on the real-time temperature.

[0065] In this embodiment of the invention, the coefficient of thermal expansion k = 0.00001.

[0066] In step S2 above, the required sawing length is calculated based on the current temperature of the rolled piece, its multiple of length, and the finished product sawing length (due to thermal expansion and contraction of the rolled piece). In particular, the calculated sawing length differs depending on the temperature of the first and second sawing cuts on the same rolled piece. The image recognition length measurement system sends the calculated sawing length of the rolled piece as a reference value to the PLC control system. Based on the measured length fed back by the length measurement server, the system performs positioning control of the rolled piece on the conveyor rollers.

[0067] In this embodiment of the invention, step S3 includes a three-stage deceleration process, namely:

[0068] In the first deceleration stage, when the workpiece is 7 to 8 meters away from the target position, the speed of the conveyor rollers is reduced from full speed to about 2.0 to 2.2 m / s, at which point the speed of the workpiece is V2;

[0069] In the second deceleration stage, when the workpiece is 2 to 3 meters away from the target position, the speed of the conveyor rollers is reduced to the preset tail-throwing speed.

[0070] In the third deceleration stage, when the workpiece is 0.1 to 0.3 m away from the target position, the roller conveyor frequency converter reduces the speed of the conveyor roller to 0 in a ramp curve manner.

[0071] In step S3 above, the rolled piece enters the hot saw area. After the head of the rolled piece is sawn, the operator starts the image recognition length measurement system, and the PLC control system simultaneously starts the pre-saw roller conveyor for rolled piece positioning. The PLC control system reads the length of the rolled piece from the image recognition length measurement system in real time via communication. The PLC control system program sends a full-speed forward command to the transmission system, with a speed of 3 m / s. At a distance of 7.5 m from the target position, the speed is reduced to 2.1 m / s. At a distance of 2.5 m from the target position, the speed is reduced to the tail-throwing speed. At a distance of 0.2 m from the target position, the reference speed is 0, and the roller conveyor frequency converter reduces the speed to 0 at a ramp.

[0072] It is particularly important to note that the deceleration setting of the roller conveyor frequency converter must be relatively small. If the deceleration setting is too large, the rolled piece will basically stop due to inertia on the roller conveyor, resulting in very inaccurate positioning and poor positioning accuracy, which cannot meet the production process requirements. When the deceleration is set to a smaller value, the inverter controls the roller conveyor speed to decrease slowly, which can effectively control the rolled piece on the roller conveyor to run, decelerate, and stop at the controlled speed. By adjusting the positioning offset value, precise positioning can finally be achieved.

[0073] In addition, Figure 3 The third platform (V3=0.55m / s) needs about 0.5 seconds to effectively dissipate inertial energy, making the final tail distance stable and achieving precise positioning.

[0074] In step S4 above, the PLC control system automatically determines the tail-scraping speed based on the relationship between the sawing length of the rolled piece and its weight per meter, as follows:

[0075] When the sawing length is greater than 40m and the weight per meter is less than 130kg / m, the tail-throwing speed is 0.5~0.6m / s;

[0076] When the sawing length is greater than 40m and the weight per meter is greater than 130kg / m, the tail-throwing speed is 0.6~0.8m / s;

[0077] When the sawing length is less than 40m and the weight per meter is greater than 200kg / m, the tail throwing speed is 0.8~1.0m / s.

[0078] In this embodiment of the invention, in step S4 above, due to differences in product sawing length, weight per meter, and the moment of inertia of the rolled piece, the tail-throwing distance varies, and the positioning accuracy cannot be consistent. Therefore, the PLC control system reads the rolling chart parameters and makes a judgment: when the sawing length is greater than 40m but the weight per meter is less than 130kg / m, the tail-throwing speed is 0.55m / s; when the length is greater than 40m but the weight per meter is greater than 130kg / m, the tail-throwing speed is 0.7m / s; when the sawing length is less than 40m but the weight per meter is less than 130kg / m, the tail-throwing speed is 0.7m / s; when the length is less than 40m and 130kg / m < weight per meter < 200kg / m, the tail-throwing speed is 0.8m / s; when the length is less than 40m and the weight per meter is greater than 200kg / m, the tail-throwing speed is 0.9m / s.

[0079] This section considers the case where the sawing length is less than 40m. The main issue is that there is a section of roller conveyor belt with a 5° inclination angle in front of the fixed saw on site (process requirement to ensure sawing quality). When the rolled piece is transported forward, it moves towards the side baffle. This creates a certain friction between the rolled piece and the side baffle. When the weight per meter of the rolled piece is large, a small speed setting cannot make the rolled piece move.

[0080] In step S5 above, the positioning compensation value is used to adjust the deceleration point position, and the positioning compensation value can be set within the range of −400mm to +400mm. When the workpiece is positioned beyond the target position, the deceleration point position is corrected by decreasing the positioning compensation value; when the workpiece is positioned below the target position, the deceleration point position is corrected by increasing the positioning compensation value, in order to compensate for the mechanical error of the roller conveyor or changes in the on-site working conditions.

[0081] In this embodiment of the invention, in step S5 above, due to the different operating conditions of the roller conveyor and roller conveyor motor on site, a positioning compensation value is set on the screen to cope with the actual situation on site: the positioning compensation value is in the range of -400mm and +400mm, which is used to correct the deceleration point, that is, to advance or postpone the deceleration point of 2.5m and 0.2m. If the positioning exceeds the target position by 50mm, then 50mm is subtracted from the positioning compensation value, and the deceleration point will become 2.55m and 0.25m; conversely, if the positioning cannot reach the target position by 50mm, then 50mm is added to the positioning compensation value, and the deceleration point will become 2.45m and 0.15m, so as to adapt to the changes in the on site conditions.

[0082] Example 1

[0083] In this embodiment, the rolled product is an H-beam, taking a 410x179x8.8x14.4mm section as an example, with a weight of 67kg / m, a universal rolling mill rolling length of 105.7m, and sawing lengths of 55.949m for the first cut and 48.755m for the second cut. Figure 5 :

[0084] The irregularly shaped billet is shaped by a billet mill, cut by a tongue-cutting saw, rolled by a universal rolling mill, and after passing through the UF mill, it is moved laterally by a chain-driven trolley on a transverse platform to the hot saw input roller table. The current sawing chart data is for the first segment. =55949mm, second segment =48755mm, offset value = -55mm; The operator first cuts off the head of the rolled piece, then presses the automatic length measurement start button. Simultaneously, the PLC control system starts the automatic transfer and positioning of the rolled piece. The PLC control system issues a command for the transfer rollers to run at full speed. The transmission cabinet receives the command, and the rollers feed the steel at full speed of 3m / s. When the rolled piece is 7.5m away from the target position, the actual length measurement value is displayed. When the length reaches (55949mm - 7500mm = 48449mm), the PLC issues a deceleration command for the roller conveyor, reducing the speed reference value from 3m / s to 2.1m / s. The transmission cabinet receives the command, and the roller conveyor decelerates according to the set deceleration rate. The roller conveyor continues to feed steel forward, and when the actual length measurement value is displayed... (55949mm - 2500mm + (-55mm) = 53394mm), the PLC issues a roller deceleration command, and the speed reference value switches to the tail-throwing speed. The tail-throwing speed is automatically selected according to the sawing length and rolling specifications. The current sawing length is greater than 40m, and the weight per meter is 67kg / m, so the tail-throwing speed is 0.55m / s; when the actual length measurement value is displayed... (55949mm - 200mm + (-55mm) = 55694mm), the PLC control system sends a command to set the reference speed to 0. The transmission cabinet receives the command and stops. The roller conveyor stops, and the screen displays the actual length measurement position as 55952, which is 3mm larger than the sawing reference value, achieving a positioning accuracy within the range of + / -30mm, which meets production needs.

[0085] In this embodiment, after the irregular billet is rolled into shape by the billet mill, it is rolled by the universal rolling mill group. After passing through the UF rolling mill (universal finishing mill), the rolled piece is transported to the hot saw input roller table through the transverse transfer table and chain conveyor trolley.

[0086] The operator selects the current sawing plan (sawing chart) on the touchscreen interface, at which point the PLC control system is already loaded with the following:

[0087] Set the first segment sawing length = 55949 mm;

[0088] Set the second segment sawing length = 48755 mm;

[0089] Set the positioning compensation value (offset) to -55 mm;

[0090] Then press the automatic length measurement start button, and the PLC program will start the automatic length measurement and positioning control logic.

[0091] During the full-speed operation phase of the roller conveyor, the PLC issues a full-speed operation transmission command → the drive cabinet executes the command → the conveyor rollers drive the rolled piece forward at a speed of 3 m / s. This phase is mainly used to quickly move the rolled piece close to the target sawing position.

[0092] Then, during the first deceleration phase, when the workpiece is about 7.5m away from the target position (i.e., the actual length measured = 55949 − 7500 = 48449mm), the PLC issues a deceleration command, and the speed of the conveyor rollers decreases from 3.0m / s to 2.1m / s.

[0093] During the second deceleration phase, when the workpiece is about 2.5m away from the target position (including the compensation offset: 55949−2500−55=53394mm), the PLC issues a tail-throwing deceleration command with a tail-throwing speed of 0.55m / s.

[0094] When the actual measured length is 55949−200−55=55694mm, the PLC issues a stop command, the conveyor roller speed is 0 m / s, and the operation stops.

[0095] After the conveyor rollers stopped, the actual length measured by the system was 55952 mm. Compared with the set sawing target value of 55949 mm, the deviation was +3 mm. The positioning accuracy allowed by the control system is ±30 mm, so the result fully meets the production requirements.

[0096] As can be seen from the control process in this embodiment, the automatic length measurement and sawing positioning method of the present invention adopts a segmented deceleration control strategy, combined with positioning compensation values ​​to achieve precise dynamic position correction. This method can effectively compensate for positioning deviations caused by factors such as equipment operating inertia and differences in roller friction, ensuring stable and reliable automatic positioning of the rolled piece under high temperature and high speed conditions. Actual test results show that the positioning deviation is controlled within ±3 mm, significantly better than the ±30 mm accuracy of traditional manual or single-segment deceleration control methods, verifying the accuracy and stability of the method of the present invention.

[0097] Example 2

[0098] In this embodiment, taking the production of 327x319x16x25 profile steel with a weight of 179 kg / m as an example, and the universal rolling mill rolling length of 86.5m with the sawing lengths as follows: first cut 36.585m / second cut 48.787m, see... Figure 6 :

[0099] The rectangular billet is shaped by the billet honing machine, cut by the tongue-cutting saw, rolled by the universal rolling mill, and after passing through the UF mill, it is moved laterally by the chain-driven trolley on the transverse platform to the hot saw input roller table. The current sawing chart data is for the first segment. =36585mm, second segment =48787mm, offset value -60mm; The operator first cuts off the head of the rolled piece, then presses the automatic length measurement start button. Simultaneously, the PLC program starts the automatic transfer and positioning of the rolled piece. The PLC program issues a command for the transfer rollers to run at full speed. The transmission cabinet receives the command, and the rollers feed the steel at full speed of 3m / s. When the rolled piece is 7.5m away from the target position, the actual length measurement value is displayed. When the length reaches (36585mm - 7500mm = 29085mm), the PLC issues a deceleration command to the roller conveyor, reducing the speed reference value from 3m / s to 2.1m / s. The transmission cabinet receives the command, and the roller conveyor decelerates according to the set deceleration rate. The roller conveyor continues to feed steel forward, and when the actual length measurement value is displayed... (36585mm - 2500mm + (-60mm) = 34025mm), the PLC issues a roller deceleration command. The speed reference value switches to the tail-throwing speed, which is automatically selected based on the sawing length and rolling specifications. Currently, the sawing length is less than 40m, and the weight per meter is 179kg / m, therefore the tail-throwing speed is 0.8m / s; when the actual length measurement value displays... (36585mm - 200mm + (-60mm) = 36325mm), the PLC sends a command to set the reference speed to 0. The transmission cabinet receives the command and decelerates to a stop according to the set deceleration speed. The roller conveyor stops, and the screen displays the actual length measurement position as 36600, which is 15mm larger than the sawing reference value, achieving a positioning accuracy within the range of + / -30mm, which meets production needs.

[0100] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. An automatic positioning method for rolled piece transfer based on image recognition length measurement technology, characterized in that, Includes the following steps: S1. During the transfer of the rolled piece, multiple cameras arranged along the transfer path are used to collect images of the rolled piece, and the images are processed and the length is calculated to obtain the real-time length information of the rolled piece. S2. Based on the current temperature of the rolled piece, the multiple of length, and the target finished product length, calculate the sawing length L of the rolled piece according to the preset formula L = (L0 + ΔL) × N × (1 + k × T), where L0 is the target finished product length, ΔL is the correction length, N is the multiple of length, T is the current temperature of the rolled piece, and k is the coefficient of thermal expansion. S3. With the fixed saw as the reference position, the PLC control system controls the speed of the conveyor rollers according to the length value of the rolled piece fed back by the image recognition length measurement system, so that the rolled piece runs at full speed and decelerates in multiple stages until it stops when it approaches the target position. S4. Automatically select the corresponding tail-throwing speed based on the sawing length and weight per meter of the rolled piece; S5. By setting the positioning compensation value, the position of the deceleration point is corrected to achieve precise positioning of the rolled piece at the fixed saw position.

2. The automatic positioning method for rolling mill transfer according to claim 1, characterized in that, In step S1, the fields of view of the cameras overlap, and the overlap range of the camera fields of view is 200mm to 600mm.

3. The automatic positioning method for rolling mill transfer according to claim 1 or 2, characterized in that, The camera is installed at a height of 3 to 5 meters above the surface of the conveyor rollers and is used in conjunction with a laser light source for supplementary lighting.

4. The automatic positioning method for rolling mill transfer according to any one of claims 1 to 3, characterized in that, In step S2, the value of the thermal expansion coefficient k ranges from (1.0 to 1.2) × 10⁻⁶. -5 Furthermore, the sawing length is calculated separately for the first and second cuts of the same rolled piece based on the real-time temperature.

5. The automatic positioning method for rolling mill transfer according to any one of claims 1 to 3, characterized in that, Step S3 includes a three-stage deceleration process, namely: In the first deceleration stage, when the workpiece is 7-8m away from the target position, the speed of the conveyor rollers is reduced from full speed to about 2.0-2.2m / s; In the second deceleration stage, when the workpiece is 2 to 3 meters away from the target position, the speed of the conveyor rollers is reduced to the preset tail-throwing speed. In the third deceleration stage, when the workpiece is 0.1 to 0.3 m away from the target position, the roller conveyor frequency converter reduces the speed of the conveyor roller to 0 in a ramp curve manner.

6. The automatic positioning method for rolling mill transfer according to any one of claims 1 to 3, characterized in that, In step S4, the PLC control system automatically determines the tail-scraping speed based on the relationship between the sawing length of the rolled piece and its weight per meter, as follows: When the sawing length is greater than 40m and the weight per meter is less than 130kg / m, the tail-throwing speed is 0.5~0.6m / s; When the sawing length is greater than 40m and the weight per meter is greater than 130kg / m, the tail-throwing speed is 0.6~0.8m / s; When the sawing length is less than 40m and the weight per meter is greater than 200kg / m, the tail throwing speed is 0.8~1.0m / s.

7. The automatic positioning method for rolling mill transfer according to any one of claims 1 to 3, characterized in that, In step S5, the positioning compensation value is used to adjust the deceleration point position, and the positioning compensation value can be set in the range of −400mm to +400mm.

8. The automatic positioning method for rolling mill transfer according to claim 7, characterized in that, When the workpiece is positioned beyond the target position, the deceleration point position is corrected by reducing the positioning compensation value; when the workpiece is positioned below the target position, the deceleration point position is corrected by increasing the positioning compensation value, in order to compensate for the mechanical error of the roller conveyor or changes in the on-site working conditions.

9. The automatic positioning method for rolling mill transfer according to any one of claims 1 to 3, characterized in that, The image recognition length measurement system establishes a length measurement coordinate system with a fixed saw as a reference calibration point, and transmits the length information of the rolled piece to the PLC control system in real time through the length measurement server to achieve closed-loop control.

10. The automatic positioning method for rolling mill transfer according to any one of claims 1 to 3, characterized in that, The image recognition length measurement system includes an image acquisition module, an image processing module, a length calculation module, and a communication module. The modules communicate with each other via industrial Ethernet or fieldbus.

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