A real-time regulation method for sheet connecting process
By monitoring temperature and pressure in real time and using a temperature-pressure coupling model for dynamic compensation, the problems of low efficiency and poor quality in the connection process of aluminum alloy thin plates are solved, and a high-efficiency and accurate connection effect is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING UNIVERSITY OF SCIENCE AND TECHNOLOGY
- Filing Date
- 2025-04-30
- Publication Date
- 2026-06-09
AI Technical Summary
Aluminum alloy thin plates suffer from problems such as low connection efficiency, poor connection quality, poor flatness at the connection point, and easy occurrence of burrs and warping deformation during the connection process. Furthermore, the temperature is easily affected by the external environment, leading to connection defects.
A connection system including a conveying component, a shearing component, an auxiliary lifting component, a sensing system, and a heating device is adopted. By monitoring temperature and pressure in real time and using a temperature-extrusion pressure coupling model for dynamic compensation, efficient connection of aluminum alloy sheets is ensured.
It enables rapid and efficient connection of thin aluminum alloy sheets, avoids connector defects, ensures the quality and mechanical properties of the connector, and improves connection accuracy and surface smoothness.
Smart Images
Figure CN122164818A_ABST
Abstract
Description
[0001] This invention is a divisional application of patent application number 2025105622199, entitled "A quick connection system for aluminum alloy thin plates". Technical Field
[0002] This invention relates to the field of material joining technology, and more specifically to a real-time control method for the thin plate joining process. Background Technology
[0003] Aluminum alloy sheet is a sheet structure with a thickness of approximately 1-5 mm made of aluminum alloy. It features lightweight, high strength, excellent corrosion resistance, and good thermal and electrical conductivity. However, due to the inherent properties of aluminum alloys—high laser reflectivity, ultra-high thermal conductivity leading to poor energy absorption and rapid heat dissipation, and difficulty in concentrating the molten pool temperature; and high internal stress due to large linear expansion / contraction, making it prone to deformation and cracking—it is difficult to achieve the same weld strength as steel through fusion welding or laser welding. Currently, existing technologies typically use friction stir welding to join aluminum alloys, but this method is inefficient and cannot be scaled up for industrial production. Furthermore, in the production of aluminum alloy sheet, laser welding is less effective and cannot be used for continuous, uninterrupted production like steel plates. Therefore, two aluminum coils are usually sewn together to join them. However, this sewing method usually requires downtime, affecting production continuity, and the sewn portion is large, requiring subsequent processing, which can lead to material waste, low efficiency, and increased costs. Currently, a large amount of research and experimental data have proven that shear extrusion joining can achieve better bonding of thin aluminum alloy sheets, and the bonding strength exceeds that of friction stir welding and traditional welding and riveting methods (e.g., Journal of Materials Science & Technology, 2023, 164:168-178). Heated shear extrusion joining achieves metallurgical bonding through shear force and plastic deformation, which can avoid problems such as hot cracking, porosity, and softening of the heat-affected zone that occur during aluminum alloy welding. The joint has high strength and good sealing performance.
[0004] However, due to the differences in extrusion shrinkage at the joint during the extrusion process and the relatively thin thickness of the aluminum alloy sheet (generally 1-5mm), the extrusion process results in: poor overall flatness at the joint; and unavoidable burrs, flash, or unevenness at the joint. This not only affects subsequent assembly performance and mechanical properties but also easily leads to scratches and damage on the production line. Simultaneously, during the heated extrusion joining of aluminum alloy sheets, the plastic deformation of the sheet mainly depends on preheating and extrusion shear force. Temperature is easily affected by external environmental factors, leading to sudden temperature changes (such as a sudden drop in temperature), causing unwelded areas or brittle fracture at the joint, and even resulting in hot cracks. While increasing the preheating temperature can mitigate the impact of temperature changes to some extent during shear extrusion joining, excessively high temperatures can cause the aluminum alloy to exceed its recrystallization temperature, leading to brittle fracture at the joint due to coarse grains. Furthermore, it can cause localized fusion of the aluminum alloy, resulting in molten aluminum alloy adhering to the extrusion head surface, thus affecting normal joining. Furthermore, during the shearing and extrusion connection process, when the temperature changes abruptly, the synchronous action of the extrusion force, i.e., the mismatch between the parameters of temperature and pressure, causes uneven thickness distribution or warping deformation. This not only affects the dimensional accuracy of the connection position but also the connection quality of the connector, resulting in poor mechanical properties of the connector. Summary of the Invention
[0005] To address the problems existing in the prior art, the present invention aims to provide a real-time control method for the thin plate joining process. This method monitors temperature and pressure in real time during the joining process of aluminum alloy thin plates, thereby enabling rapid and efficient joining of complete aluminum alloy thin plates and avoiding problems such as connector defects and poor connection quality caused by external environmental influences during the joining process.
[0006] The objective of this invention is achieved through the following technical solution: A real-time control method for thin plate joining process employs a connection system including a conveying assembly, a shearing assembly, an auxiliary lifting assembly, a sensing system, and a heating device. The conveying assembly consists of two sets of conveying mechanisms with a shearing assembly positioned between them. Each set of conveying mechanisms comprises multiple conveying rollers, with the upper tangent surfaces of the rollers located on the same horizontal plane. The shearing assembly includes an upper shearing head and a lower shearing head, with shearing grooves respectively formed in the middle of the bottom surface of the upper shearing head and the middle of the top surface of the lower shearing head. The shearing grooves of the upper and lower shearing heads are mirror-symmetrical (i.e., the upper shearing head rotates 180° around its center to perfectly align with the lower shearing head). The auxiliary lifting assembly is positioned outside the two conveying rollers of one set of conveying mechanisms and includes two auxiliary lifting rollers and a lifting device. The two auxiliary lifting rollers are arranged in parallel, with their ends connected to the lifting device, which controls the synchronous lifting and lowering of the two auxiliary lifting rollers. The sensing system is positioned corresponding to the shearing assembly.
[0007] Based on further optimization of the above scheme, the shearing groove consists of two arc segments, including a small arc segment and a large arc segment. The small arc segment and the large arc segment are smoothly connected, and the shearing groove of the upper shearing head is conveyed by the conveying component in the order of the small arc segment and the large arc segment. The radius of the small arc segment is 3 times the thickness of the aluminum alloy sheet, and the radius of the large arc segment is 6 times the thickness of the aluminum alloy sheet. The length of the shearing groove is no more than 5 times the thickness of the aluminum alloy sheet; the length of the flat sections on both sides of the shearing groove is consistent and greater than 5 times the thickness of the aluminum alloy sheet.
[0008] Based on further optimization of the above scheme, the sensing system includes an infrared sensor, a temperature sensor, and a pressure sensor. The infrared sensor is located on the side of the shearing assembly near the auxiliary lifting assembly and includes an infrared emitting source and an infrared receiving source. The infrared emitting source and the infrared receiving source are respectively located on the lower shear head and the upper shear head, and the infrared emitting source and the infrared receiving source are correspondingly arranged. The temperature sensor is located on the bottom surface of the upper shear head on the side of the corresponding shearing groove near the auxiliary lifting assembly, and the temperature sensor is evenly distributed along the width direction of the upper shear head. The pressure sensor (e.g., a high-temperature strain gauge sensor) is located on the top surface of the lower shear head on the side of the corresponding shearing groove away from the auxiliary lifting assembly, and the pressure sensor is evenly distributed along the width direction of the lower shear head.
[0009] Based on further optimization of the above scheme, the heating device is located on the front and rear sides of the shearing assembly and is set at the overlapping part of the stacked aluminum alloy sheets. The heating device can clamp the aluminum alloy sheets. At the same time, an infrared thermal imager is set on the front and rear sides of the shearing assembly and above the heating device. The line of sight of the infrared thermal imager is opposite to the overlapping position of the aluminum alloy sheets.
[0010] A real-time control method for the thin plate joining process includes: Step 1, aluminum alloy thin plate stacking: placing the aluminum alloy thin plate on a conveying assembly, so that the aluminum alloy thin plate follows the conveying assembly; when the tail of the previous aluminum alloy thin plate is located in the middle of the shearing groove of the lower shear head, pausing the operation of one side of the conveying mechanism (i.e., the conveying mechanism away from the auxiliary lifting assembly), and placing the next aluminum alloy thin plate on another conveying mechanism (i.e., the conveying mechanism equipped with the auxiliary lifting assembly), the next aluminum alloy thin plate follows the conveying mechanism; when the end of the next aluminum alloy thin plate is detected by an infrared sensor, the corresponding conveying mechanism stops, the auxiliary lifting roller is raised and rotated, realizing the lifting and continuous operation of the next aluminum alloy thin plate, so that the end of the next aluminum alloy thin plate moves... Upon reaching the middle of the shearing groove of the upper shear head, the auxiliary lifting roller stops running, the upper shear head moves down to contact the bottom surface with the end face of the next aluminum alloy sheet, the upper shear head pauses running, and then the auxiliary lifting roller descends to reset; Step 2, Heating the aluminum alloy sheet: First, drive the front and rear heating devices to form a clamp on the stacked aluminum alloy sheets; then, start the heating devices to heat the aluminum alloy sheets; after heating is completed, the front and rear heating devices release the clamp on the aluminum alloy sheets; Step 3, Extrusion connection: Simultaneously start the upper and lower shear heads, making them move towards each other to achieve the shearing connection of the two aluminum alloy sheets; during the connection process, the temperature and pressure are monitored simultaneously to achieve pressure compensation and heating temperature optimization.
[0011] Based on further optimization of the above scheme, the diameter of the auxiliary lifting roller is 2 to 4 times the diameter of the conveying roller, and the lifting height of the auxiliary lifting roller is 1 to 3 times the thickness of the aluminum alloy sheet; in the initial state, the top of the auxiliary lifting roller is located 0.2 to 2 mm below the top of the conveying roller.
[0012] Based on the further optimization of the above scheme, step three involves monitoring temperature and pressure to achieve pressure compensation and heating temperature optimization, specifically as follows: First, using the law of conservation of energy, predict the temperature of the connector at the next moment:
[0013] In the formula: T(t+1) This indicates the predicted temperature for the next moment. T(t) Indicates the current temperature; Q f This represents the heat generated by friction during the extrusion process. Q e This indicates the amount of heat generated by external heating. Q l This indicates the heat loss; Indicates the density of the material. A c Indicates the contact area of the connector. h Indicates the thickness of the aluminum alloy sheet.c p Indicates the specific heat capacity of the material; Indicates the time step between the next moment and the current moment; in:
[0014] In the formula: Indicates the internal frictional properties of an object; F(t) This represents a time-dependent extrusion pressure function; This indicates the extrusion head speed as it changes over time. H c Indicates the convective heat transfer coefficient; T n This indicates the measured temperature of the aluminum alloy sheet at a given moment. T a Indicates ambient temperature; A l Indicates the heat dissipation area; Indicates the emissivity of the material; This represents the Stefan-Boltzmann constant; Then, by combining a temperature sensor with an infrared thermal imager, the actual temperature of the connector at the next moment is obtained. T 0; if T 0 and T(t+1) If the deviation is greater than the preset deviation threshold (the deviation threshold is set according to the time step), it indicates that a temperature change has occurred during the extrusion process and is compensated by changing the extrusion pressure; otherwise, it indicates that no temperature change has occurred. Simultaneously, the initial temperature, actual temperature, and adjustment amount of extrusion pressure (if there is a temperature change) of each extrusion process are recorded, an objective function is constructed, and the initial temperature is optimized through machine learning.
[0015] Based on further optimization of the above scheme, the method for obtaining the actual temperature of the connector at the next moment is as follows: First, the emissivity of the aluminum alloy sheet is calibrated by pre-calibrated blackbody furnace (since the emissivity of the aluminum alloy surface is affected by oxidation degree, roughness, etc., calibration can effectively reduce the error caused by oxidation degree and roughness).
[0016] In the formula: Indicates the surface radiance of the aluminum alloy; Indicates the radiance of a blackbody; T Indicates the target temperature; H p Represents Planck's constant; c Represents the speed of light; Indicates the operating wavelength of the infrared thermal imager; kRepresents the Boltzmann constant; Then, based on the brightness difference between the heated area and the background radiation, the infrared thermal imager image is segmented using the Otsu algorithm to extract the initial ROI region; and the Canny operator is used to detect the edge of the heated area, combined with morphological operations (such as dilation, erosion, etc.) to remove noise, ensuring that the ROI region accurately covers the heated area. Next, the measured brightness of each pixel within the ROI region is obtained. And perform environmental parameter corrections, including reflected radiation correction and atmospheric attenuation correction: Correction for reflected radiation:
[0017] In the formula: T a The ambient temperature is displayed, and the ambient brightness is obtained by combining the ambient temperature with Planck's law. ; Atmospheric attenuation correction:
[0018] In the formula: Indicates distance as D The atmospheric transmittance, i.e., the distance between the infrared thermal imager and the aluminum alloy heating zone, is... D ; The corrected radiance is used to obtain the corresponding temperature value detected by the infrared thermal imager. T X :
[0019] Because the infrared thermal imager detects the heating areas on the front and rear edges of the aluminum alloy sheet, while the heating area in the middle is blocked by the upper and lower shear heads, the infrared imaging temperature measurement will have a large deviation. Therefore, by coordinating the temperature sensors evenly distributed on the upper shear head with the infrared thermal imager's detection results, accurate temperature feedback can be achieved. Specifically: The corresponding detection temperature is obtained in real time using temperature sensors on the front and rear sides of the upper shear head. T c-b And detect the temperature using a temperature sensor. T c-b Temperature detected by infrared thermal imager at the corresponding time T X Obtain the temperature of each temperature sensor point in the middle of the upper shear head. T c-ni ( i = 1,2,…,n-2 The corresponding actual temperature value T x-i ,in, nIndicates the number of temperature sensors on the upper shear head:
[0020] Finally, the actual temperature values at each point were fitted. T x-i and T X This refers to the actual temperature of the heating zone of the aluminum alloy sheet at the current moment. T 0.
[0021] Based on further optimization of the above scheme, the method of compensating for temperature abrupt changes by extrusion pressure is specifically as follows: First, establish a temperature-compression pressure coupling model:
[0022] In the formula: F Indicates compressive force. This indicates the flow stress of the aluminum alloy. f Indicates the friction factor; a , b m is a material constant (obtained from experimental data, n is usually 0.5 to 2), Q represents the deformation activation energy, and R represents the gas constant. Indicates strain rate (determined by extrusion rate). Represents the inverse hyperbolic sine function; L , d These represent the length and width of the connector area, respectively. Based on the current real-time temperature T 0. The target value of extrusion pressure is obtained through a temperature-extrusion pressure coupling model. F m ; Then, based on the temperature deviation Dynamic compensation of extrusion pressure is achieved using a PID controller:
[0023]
[0024] In the formula: K p , K i , K d These represent the proportional coefficient, integral coefficient, and derivative coefficient of the PID controller, respectively.
[0025] Based on further optimization of the above scheme, the objective function is specifically as follows:
[0026] In the formula: , These represent the weighting coefficients, which are set according to the actual situation. This represents the amount of pressure adjustment for the i-th time; T ci Indicates the first i The initial extrusion temperature recorded for this time; T best Indicates the historical best temperature; By constructing intelligent models (such as random forests or deep neural network models), the optimal initial temperature is predicted. Input features include ambient temperature, plate thickness, and historical process parameters.
[0027] The following are the technical effects of the present invention: This invention utilizes a temperature-extrusion pressure coupling model established through real-time monitoring and prediction by a sensing system during the heating and extrusion process of aluminum alloy sheets. By compensating for extrusion pressure, it avoids abrupt temperature changes caused by external environmental influences, thereby preventing problems such as rapid hardening of the alloy material, reduced plastic flowability, hot cracking due to extrusion stress, and coarse grains in the molten state caused by external environmental factors. This ensures the short-term plastic deformation and recrystallization capacity of the aluminum alloy sheet joint area, thus guaranteeing the quality and mechanical properties of the joint. Simultaneously, the connection between aluminum alloy sheets is achieved through various processes such as heating, extrusion, shearing, and friction, utilizing metallic bonds to tightly connect the two metals together. Furthermore, during the thin plate joining process, by setting a double-arc segment shearing groove structure on the upper and lower shearing heads respectively, it can not only provide a buffer space for the plastically deformed aluminum alloy thin plate connector and avoid stress concentration points caused by abrupt changes in the joint after joining, resulting in low mechanical properties of the joint; it can also ensure the smoothness of the connector surface during the extrusion process, avoiding problems such as burrs and flash caused by warping of the thin plate edge due to pressure, and preventing burrs and flash defects from scratching the production line; the double-arc segment shearing groove structure design can also improve the metal atom rearrangement and grain refinement process during extrusion, thereby improving the strength and mechanical properties of the connector. Attached Figure Description
[0028] Figure 1 This is a schematic diagram of the structure of the aluminum alloy sheet quick connection system in an embodiment of the present invention.
[0029] Figure 2 for Figure 1 A magnified view of part A in the image.
[0030] Figure 3 for Figure 1 BB-direction sectional view.
[0031] Figure 4This is a tensile curve diagram of the aluminum alloy sheet connection system of the present invention.
[0032] Figure 5 This is a microstructure diagram of the connection position after aluminum alloy thin plates are connected using the connection system of the present invention.
[0033] Among them, 10 is an aluminum alloy sheet; 11 is a conveying roller; 20 is a shearing groove; 21 is an upper shearing head; 22 is a lower shearing head; 31 is an auxiliary lifting roller; 411 is an infrared receiver; 412 is an infrared emitter; 42 is a temperature sensor; 43 is a pressure sensor; 51 is a heating device; and 52 is an infrared thermal imager. Detailed Implementation
[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. In the following description, specific details such as specific system structures and technologies are presented for illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention.
[0035] Example 1: A real-time control method for thin plate joining process employs a connection system including a conveying assembly, a shearing assembly, an auxiliary lifting assembly, a sensing system, and a heating device 51. The conveying assembly consists of two sets of conveying mechanisms, with a shearing assembly (such as...) positioned between the two sets of conveying mechanisms. Figure 1 As shown), both sets of conveying mechanisms consist of multiple conveying rollers 11, and the upper tangent surfaces of the multiple conveying rollers 11 are located on the same horizontal plane (e.g., Figure 1 As shown, two conveyor rollers 11 are respectively arranged on the left and right sides of the shearing assembly. The number of conveyor rollers 11 on each side is set according to the actual length of the aluminum alloy sheet 10. The two conveyor rollers 11 in this embodiment are only for example and are not intended to limit the solution of the present invention. The shearing assembly includes an upper shearing head 21 and a lower shearing head 22, and shearing grooves 20 are respectively formed in the middle of the bottom surface of the upper shearing head 21 and the middle of the top surface of the lower shearing head 22 (e.g., Figure 1 As shown), the shearing groove 20 of the upper shear head 21 and the shearing groove 20 of the lower shear head 22 are mirror symmetrical (i.e., the upper shear head 21 rotates 180° around its center and is completely consistent with the lower shear head 22, as shown). Figure 1 (As shown); the shear groove 20 consists of two arc segments, including a small arc segment and a large arc segment (as shown). Figure 2 As shown), the small arc segment and the large arc segment are smoothly connected, and the shearing groove 20 of the upper shear head 21 is conveyed by the conveying assembly in the direction (i.e., Figure 1 (As shown from left to right) are small arc segments and large arc segments respectively (the shearing groove 20 of the lower shear head 22 is conveyed by the conveying assembly, i.e.) Figure 1 The diagram shows the large and small arc segments from left to right. The radius of the small arc segment is three times the thickness of the aluminum alloy sheet (e.g., ...). Figure 2 As shown, in this embodiment, assuming the thickness of the aluminum alloy sheet 10 is h, then the radius of segment bq is 3h, and the radius of the large arc segment is 6 times the thickness of the aluminum alloy sheet 10 (i.e., the radius of segment cq is 6h). The length of the shearing groove 20 is no greater than 5 times the thickness of the aluminum alloy sheet 10 (i.e., the length of segment bc ≤ 5h); the lengths of the flat sections on both sides of the shearing groove 20 are consistent (i.e., ab=cd, ef=gh) and greater than 5 times the thickness of the aluminum alloy sheet 10 (i.e., ab>5h). Furthermore, if the thickness of the aluminum alloy sheet 10 is less than 1mm, then the lengths of the flat sections on both sides of the shearing groove 20 (i.e., segments ab, ca, ef, and gh) are greater than 5mm. An auxiliary lifting assembly is set in a set of conveying mechanisms (i.e.,... Figure 1 The outer side of the two conveying rollers 11 of the set of conveying mechanisms on the left side includes two auxiliary lifting rollers 31 and a lifting device. The two auxiliary lifting rollers 31 are arranged in parallel and their two ends are respectively connected to the lifting device. The lifting device is used to control the synchronous lifting of the two auxiliary lifting rollers 31 (the lifting device can be a conventional hydraulic lifting device in the art, which is provided with brackets at the two ends of the auxiliary lifting rollers 31 and the two ends of the auxiliary lifting rollers 31 are respectively rotatably connected to the brackets, and the brackets are provided with motors that drive the auxiliary lifting rollers 31).
[0036] The sensing system is configured to correspond to the shearing assembly. The sensing system includes an infrared sensor, a temperature sensor 42, and a pressure sensor 43. The infrared sensor is located on the side of the shearing assembly closest to the auxiliary lifting assembly (i.e.,...). Figure 1 (As shown on the left), including an infrared emitter 412 and an infrared receiver 411, the infrared emitter 412 and the infrared receiver 411 are respectively set to correspond to the lower shear head 22 and the upper shear head 21, and the infrared emitter 412 and the infrared receiver 411 are set to correspond (e.g. Figure 1 (As shown); the temperature sensor 42 is located on the upper shear head 21 on the side of the corresponding shear groove 20 near the auxiliary lifting component (i.e. Figure 1 The bottom surface of the upper shear head 21 (as shown on the left side of the shear groove 20) and the temperature sensors 42 are evenly distributed along the width direction of the upper shear head 21 (e.g., Figure 3 As shown, the number of temperature sensors 42 is set according to the actual detection accuracy and the width of the upper shear head 21; the pressure sensor 43 (e.g., a high-temperature strain gauge sensor) is located on the lower shear head 22 on the side of the corresponding shear groove 20 away from the auxiliary lifting component (i.e., Figure 1 The pressure sensors 43 are evenly distributed along the width direction of the lower shear head 22, on the top surface corresponding to the right side of the shear groove 20 (as shown). Figure 3 As shown, the pressure sensor 43 is configured according to the actual detection accuracy and the width of the lower shear head 22. The heating device 51 is located on the front and rear sides of the shear assembly (i.e., Figure 3 (as shown on the left and right sides) and corresponding to the overlapping parts of the stacked aluminum alloy sheets 10 (such as...) Figure 3 As shown), the heating device 51 can clamp the aluminum alloy sheet 10; at the same time, infrared thermal imagers 52 are installed on the front and rear sides of the shearing assembly and on the upper side of the heating device 51, and the line of sight of the infrared thermal imagers 52 is opposite to the overlapping position of the aluminum alloy sheet 10 (e.g., Figure 3 (As shown).
[0037] The tensile curve and microstructure after connection using the system in this embodiment are as follows: Figure 4 and Figure 5 As shown. Among them, Figure 4 The difference between process 1 and process 2 lies in the vertical distance between points b and g. In the actual process, points b and g are perpendicular lines, and their distance is adjusted according to the plate thickness. In this embodiment, after shearing and extrusion, the vertical distance between points b and g in process 1 is 0.8h, while in process 2 it is 1h.
[0038] Example 2: A real-time control method for thin plate joining process, comprising: Step 1: Stacking of aluminum alloy sheets: Place the aluminum alloy sheets on the conveyor assembly, allowing the sheets to move along with the assembly (i.e., the aluminum alloy sheets 10 are moved by the conveyor rollers 11 as if...). Figure 1 (The direction shown is from left to right); when the tail of the current aluminum alloy sheet 10 is in the middle of the shearing groove 20 of the lower shear head, the side conveying mechanism is paused (i.e., Figure 1 The conveyor mechanism on the right side, away from the auxiliary lifting assembly, is in operation, that is, the forward movement of the previous aluminum alloy sheet 10 is paused. The operation and pause of the right-side conveyor mechanism can be controlled via an infrared sensor: When the aluminum alloy sheet 10 blocks the infrared sensor, the infrared receiver 411 cannot receive the signal from the infrared transmitter 412. As the aluminum alloy sheet 10 continues to be conveyed, its tail reaches the infrared sensor and continues to operate. The signal emitted by the infrared transmitter 412 is no longer blocked by the aluminum alloy sheet 10 and is received by the infrared receiver 411. Timing begins from this moment, utilizing the conveying speed of the conveyor roller 11. v The distance from the center of the shear groove 20 of the lower shear head 22 to the infrared sensor is used to obtain the pause time of the right-side conveyor mechanism. t 1:
[0039] In the formula: l ef The length of segment ef. l fg The length of the shear groove segment fg; The next aluminum alloy sheet 10 is placed in another conveying mechanism (i.e. Figure 1On the conveyor mechanism (shown on the left side, where an auxiliary lifting component is provided), the next aluminum alloy sheet 10 follows the conveyor mechanism. When the end of the next aluminum alloy sheet 10 is detected by an infrared sensor (i.e., when the next aluminum alloy sheet 10 is not present, the infrared receiver 411 continuously receives the signal from the infrared emitter 412; when the next aluminum alloy sheet 10 is present, the infrared emitter 412 is blocked, and this is used for timing), the corresponding conveyor mechanism stops, and the auxiliary lifting roller 31 is raised and rotated. The diameter of the auxiliary lifting roller 31 is 2 to 3 times the diameter of the conveyor roller 11. The lifting height of the auxiliary lifting roller 31 is 1 to 3 times the thickness of the aluminum alloy sheet 10 (the core of the auxiliary lifting roller 31 is made of steel pipe or steel rod, and the outer ring is made of flexible materials such as polyurethane and rubber to avoid scratching the aluminum sheet); in the initial state, the top of the auxiliary lifting roller 31 is located 0.2 to 2 mm below the top of the conveying roller 11; to achieve the lifting and continuous operation of the next aluminum alloy sheet 10, so that the end of the next aluminum alloy sheet 10 runs to the middle of the shearing groove 20 of the upper shear head 21, and is conveyed by the speed of the auxiliary lifting roller 31. v 2. The distance from the middle of the shear groove 20 of the upper shear head 21 to the infrared sensor is used to obtain the time at this moment. t 2:
[0040] In the formula: l bc The length of the shear groove bc segment of the upper shear head 21; At this time: the auxiliary lifting roller stops running, the upper shear head 21 moves down to the bottom surface and contacts the end face of the next aluminum alloy sheet 10, the upper shear head 21 stops running, and then the auxiliary lifting roller 31 descends to reset. Step 2, Heating the aluminum alloy sheet: First, drive the front and rear heating devices 51 to operate (i.e., Figure 3 The heating devices 51 on both sides move towards each other to form a clamp on the stacked aluminum alloy sheet 10; then, the heating devices 51 are activated to heat the aluminum alloy sheet 10 (the heating time is about 1 minute and the target temperature is about 400℃); after the heating is completed, the front and rear heating devices 51 release the clamp on the aluminum alloy sheet 10. Step 3, Extrusion Connection: Simultaneously activate the upper shear head 21 and the lower shear head 22 (via a hydraulic mechanism) to move them towards each other, achieving the shear connection of the two aluminum alloy sheets 10; during the connection process, monitor the temperature and pressure simultaneously to achieve pressure compensation and heating temperature optimization, specifically: Step 3-1, predict the temperature of the connector at the next moment using the law of conservation of energy:
[0041] In the formula: T(t+1) This indicates the predicted temperature for the next moment. T(t)Indicates the current temperature; Q f This represents the heat generated by friction during the extrusion process. Q e This indicates the amount of heat generated by external heating. Q l This indicates the heat loss; Indicates the density of the material. A c Indicates the contact area of the connector. h Indicates the thickness of the aluminum alloy sheet. c p Indicates the specific heat capacity of the material; Indicates the time step between the next moment and the current moment; in:
[0042] In the formula: Indicates the internal frictional properties of an object; F(t) This represents a time-dependent extrusion pressure function; This indicates the extrusion head speed as it changes over time. H c Indicates the convective heat transfer coefficient; T n This indicates the measured temperature of the aluminum alloy sheet at a given moment. T a Indicates ambient temperature; A l Indicates the heat dissipation area; Indicates the emissivity of the material; This represents the Stefan-Boltzmann constant.
[0043] Step 3-2: By combining a temperature sensor with an infrared thermal imager, obtain the actual temperature of the connector at the next moment. T 0. Specifically, the emissivity of the aluminum alloy sheet is calibrated using a pre-calibrated blackbody furnace (since the surface emissivity of aluminum alloy is affected by oxidation and roughness, calibration can effectively reduce the errors caused by oxidation and roughness).
[0044] In the formula: Indicates the surface radiance of the aluminum alloy; Indicates the radiance of a blackbody; T Indicates the target temperature; H p Represents Planck's constant; c Represents the speed of light; Indicates the operating wavelength of the infrared thermal imager; k Represents the Boltzmann constant; Based on the brightness difference between the heated area and the background radiation, the infrared thermal image is segmented using the Otsu algorithm (any conventional Otsu algorithm in this field can be used, and no further limitations are imposed in this embodiment), and the initial ROI region is extracted; the Canny operator is used to detect the edge of the heated area, and morphological operations (such as dilation, erosion, etc.) are combined to remove noise, ensuring that the ROI region accurately covers the heated area. Obtain the measured brightness of each pixel within the ROI region. And perform environmental parameter corrections, including reflected radiation correction and atmospheric attenuation correction: Correction for reflected radiation:
[0045] In the formula: T a The ambient temperature is displayed, and the ambient brightness is obtained by combining the ambient temperature with Planck's law. ; Atmospheric attenuation correction:
[0046] In the formula: Indicates distance as D The atmospheric transmittance, i.e., the distance between the infrared thermal imager and the aluminum alloy heating zone, is... D ; The corrected radiance is used to obtain the corresponding temperature value detected by the infrared thermal imager. T X :
[0047] Because the infrared thermal imager detects the heating areas on the front and rear edges of the aluminum alloy sheet, while the central heating area is obscured by the upper and lower shear heads, significant deviations occur in the infrared imaging temperature measurement. Therefore, accurate temperature feedback is achieved by coordinating the temperature sensors evenly distributed on the upper shear head with the infrared thermal imager's detection results. Specifically, the temperature sensors on the front and rear sides of the upper shear head are used to acquire the corresponding detection temperatures in real time. T c-b And detect the temperature using a temperature sensor. T c-b Temperature detected by infrared thermal imager at the corresponding time T X Obtain the temperature of each temperature sensor point in the middle of the upper shear head. T c-ni ( i = 1, 2,…,n-2 The corresponding actual temperature value T x-i ,in, nIndicates the number of temperature sensors on the upper shear head:
[0048] Fit the actual temperature values at each point T x-i and T X (Temperature fitting is performed by averaging or other similar linear fitting methods), which represents the actual temperature of the heating area of the aluminum alloy sheet at the current moment. T 0.
[0049] Step 3-3, if T 0 and T(t+1) If the deviation exceeds a preset deviation threshold (the deviation threshold is specifically set according to the time step), it indicates that a temperature abrupt change has occurred during extrusion. This is compensated for by changing the extrusion pressure. Specifically, a temperature-extrusion pressure coupling model is established:
[0050] In the formula: F Indicates compressive force. This indicates the flow stress of the aluminum alloy. f Indicates the friction factor; a , b m is a material constant (obtained from experimental data, n is usually 0.5 to 2), Q represents the deformation activation energy, and R represents the gas constant. Indicates strain rate (determined by extrusion rate). Represents the inverse hyperbolic sine function; L , d These represent the length and width of the connector area, respectively. Based on the current real-time temperature T 0. The target value of extrusion pressure is obtained through a temperature-extrusion pressure coupling model. F m ; Based on temperature deviation Dynamic compensation of extrusion pressure is achieved using a PID controller:
[0051]
[0052] In the formula: K p , K i , K d These represent the proportional coefficient, integral coefficient, and derivative coefficient of the PID controller, respectively.
[0053] Conversely, it indicates that no temperature change has occurred (connection can be performed according to the predetermined extrusion pressure).
[0054] Steps 3-4: Record the initial temperature, actual temperature, and pressure adjustment for each extrusion process (if there are temperature abrupt changes), and construct the objective function, specifically:
[0055] In the formula: , These represent the weighting coefficients, which are set according to the actual situation. This represents the amount of pressure adjustment for the i-th time; T ci Indicates the first i The initial extrusion temperature recorded for this time; T best Indicates the historical best temperature; Minimize Indicates the goal of minimization; Initial temperature optimization is achieved through machine learning, which involves building intelligent models (such as random forests or deep neural network models) to predict the optimal initial temperature. Input features include ambient temperature, sheet thickness, and historical process parameters.
Claims
1. A real-time control method for the thin plate joining process, characterized in that: The system employs a connection system comprising a conveying assembly, a shearing assembly, an auxiliary lifting assembly, a sensing system, and a heating device. The conveying assembly consists of two sets of conveying mechanisms, with a shearing assembly positioned between them. Each set of conveying mechanisms comprises multiple conveying rollers, with the upper tangential surfaces of these rollers located on the same horizontal plane. The shearing assembly includes an upper shearing head and a lower shearing head, with shearing grooves respectively formed in the middle of the bottom surface of the upper shearing head and the middle of the top surface of the lower shearing head. The shearing grooves of the upper and lower shearing heads are mirror-symmetrical. The auxiliary lifting assembly is located outside the two conveying rollers of one set of conveying mechanisms and includes two auxiliary lifting rollers and a lifting device. The two auxiliary lifting rollers are arranged in parallel, with their ends connected to the lifting device, which controls the synchronous lifting and lowering of the two auxiliary lifting rollers. The sensing system is positioned corresponding to the shearing assembly. Specific methods include: Step 1: Stack aluminum alloy sheets; Step 2: Heat aluminum alloy sheets; Step 3: Extrusion connection; Specifically, the extrusion connection involves simultaneously activating the upper and lower shear heads and moving them towards each other to shear and connect the two aluminum alloy sheets; During the connection process, temperature and pressure are monitored simultaneously to achieve pressure compensation and heating temperature optimization.
2. The real-time control method for thin plate joining process according to claim 1, characterized in that: The shearing groove consists of two arc segments, a small arc segment and a large arc segment, which are smoothly connected. The shearing groove of the upper shearing head is conveyed by the conveying assembly in the order of the small arc segment and the large arc segment. The radius of the small arc segment is 3 times the thickness of the aluminum alloy sheet, and the radius of the large arc segment is 6 times the thickness of the aluminum alloy sheet. The length of the shearing groove is no more than 5 times the thickness of the aluminum alloy sheet. The flat sections on both sides of the shearing groove are of equal length and are greater than 5 times the thickness of the aluminum alloy sheet. The sensing system includes an infrared sensor, a temperature sensor, and a pressure sensor. The infrared sensor is located on the side of the shearing assembly near the auxiliary lifting assembly, and includes an infrared emitter and an infrared receiver. The infrared emitter and receiver are respectively located on the lower shear head and the upper shear head, and the infrared emitter and receiver are respectively located on the upper shear head. The temperature sensor is located on the bottom surface of the upper shear head on the side of the corresponding shearing groove near the auxiliary lifting assembly, and the temperature sensor is evenly distributed along the width direction of the upper shear head. The pressure sensor is located on the top surface of the lower shear head on the side of the corresponding shearing groove away from the auxiliary lifting assembly, and the pressure sensor is evenly distributed along the width direction of the lower shear head.
3. A real-time control method for thin plate joining process according to claim 1 or 2, characterized in that: The heating device is located on the front and rear sides of the shearing assembly and is set at the overlapping part of the stacked aluminum alloy sheets. The heating device can clamp the aluminum alloy sheets. At the same time, an infrared thermal imager is set on the front and rear sides of the shearing assembly and above the heating device. The line of sight of the infrared thermal imager is opposite to the overlapping position of the aluminum alloy sheets.
4. A real-time control method for thin plate joining process as described in claim 2 or 3, characterized in that: The specific control methods are as follows: Step 1: Stacking Aluminum Alloy Sheets: Place the aluminum alloy sheets on the conveying assembly, allowing them to follow the assembly. When the tail of the first aluminum alloy sheet is in the middle of the shearing groove of the lower shear head, pause one side of the conveying mechanism and place the next aluminum alloy sheet on another conveying mechanism. The next sheet will then follow the conveying mechanism. When the end of the next aluminum alloy sheet is detected by the infrared sensor, the corresponding conveying mechanism stops, and the auxiliary lifting roller rises and rotates, lifting and continuously running the next aluminum alloy sheet until its end reaches the middle of the shearing groove of the upper shear head. At this point, the auxiliary lifting roller stops, the upper shear head moves down to contact the end face of the next aluminum alloy sheet, and pauses. Then, the auxiliary lifting roller descends and resets. The diameter of the auxiliary lifting roller is 2 to 4 times the diameter of the conveying roller, and its lifting height is 1 to 3 times the thickness of the aluminum alloy sheet. Initially, the top of the auxiliary lifting roller is located 0.2 to 2 mm below the top of the conveying roller. Step 2, Heating the aluminum alloy sheet: First, drive the front and rear heating devices to clamp the stacked aluminum alloy sheets; then, start the heating devices to heat the aluminum alloy sheets; after heating is completed, the front and rear heating devices release the clamps on the aluminum alloy sheets. Step 3, Extrusion Connection: Simultaneously start the upper and lower shear heads and make them move towards each other to achieve the shear connection of the two aluminum alloy sheets; during the connection process, the temperature and pressure are monitored simultaneously to achieve pressure compensation and heating temperature optimization.
5. The real-time control method for the thin plate joining process according to claim 4, characterized in that: In step three, temperature and pressure are monitored to achieve pressure compensation and heating temperature optimization. Specifically, this involves: First, using the law of conservation of energy, predict the temperature of the connector at the next moment: In the formula: T(t+1) This indicates the predicted temperature for the next moment. T(t) Indicates the current temperature; Q f This represents the heat generated by friction during the extrusion process. Q e This indicates the amount of heat generated by external heating. Q l Indicates the heat lost; Indicates the density of the material. A c Indicates the contact area of the connector. h Indicates the thickness of the aluminum alloy sheet. c p Indicates the specific heat capacity of the material; Indicates the time step between the next moment and the current moment; in: In the formula: Indicates the internal frictional properties of an object; F(t) This represents a time-dependent extrusion pressure function; This indicates the extrusion head speed as it changes over time. H c Indicates the convective heat transfer coefficient; T n This indicates the measured temperature of the aluminum alloy sheet at a given moment. T a Indicates ambient temperature; A l Indicates the heat dissipation area; Indicates the emissivity of the material; This represents the Stefan-Boltzmann constant; Then, by combining a temperature sensor with an infrared thermal imager, the actual temperature of the connector at the next moment is obtained. T 0; if T 0 and T(t+1) If the deviation is greater than the preset deviation threshold, it indicates that a temperature change has occurred during the extrusion process, which is compensated for by changing the extrusion pressure; otherwise, it indicates that no temperature change has occurred. Simultaneously, the initial temperature, actual temperature, and pressure adjustment amount of each extrusion process are recorded to construct an objective function, and the initial temperature is optimized through machine learning.
6. The real-time control method for thin plate joining process according to claim 5, characterized in that: The specific method for obtaining the actual temperature of the connector at the next moment is as follows: First, the emissivity of the aluminum alloy sheet is calibrated using a pre-defined blackbody furnace calibration: In the formula: Indicates the surface radiance of the aluminum alloy; Indicates the radiance of a blackbody; T Indicates the target temperature; H p Represents Planck's constant; c Represents the speed of light; Indicates the operating wavelength of the infrared thermal imager; k Represents the Boltzmann constant; Then, based on the brightness difference between the heated area and the background radiation, the infrared thermal imager image is segmented using the Otsu algorithm to extract the initial ROI region; and the Canny operator is used to detect the edge of the heated area, combined with morphological operations to remove noise, ensuring that the ROI region accurately covers the heated area. Next, the measured brightness of each pixel within the ROI region is obtained. And perform environmental parameter corrections, including corrections for reflected radiation and atmospheric attenuation. Correction for reflected radiation: In the formula: T a The ambient temperature is used to determine the ambient brightness, which is obtained by combining the ambient temperature with Planck's law. ; Atmospheric attenuation correction: In the formula: Indicates distance as D The atmospheric transmittance, i.e., the distance between the infrared thermal imager and the aluminum alloy heating zone, is... D ; The corrected radiance is used to obtain the corresponding temperature value detected by the infrared thermal imager. T X : By coordinating the detection results of temperature sensors evenly distributed on the upper shear head with those of an infrared thermal imager, accurate temperature feedback is achieved, specifically as follows: The corresponding detection temperature is obtained in real time using temperature sensors on the front and rear sides of the upper shear head. T c-b And detect the temperature using a temperature sensor. T c-b Temperature detected by infrared thermal imager at the corresponding time T X Obtain the temperature of each temperature sensor point in the middle of the upper shear head. T c-ni ( i = 1,2,…,n-2 The corresponding actual temperature value T x-i ,in, n Indicates the number of temperature sensors on the upper shear head: Finally, the actual temperature values at each point were fitted. T x-i and T X This refers to the actual temperature of the heating zone of the aluminum alloy sheet at the current moment. T 0.
7. The real-time control method for thin plate joining process according to claim 6, characterized in that: The method of compensating for temperature changes by applying extrusion pressure is specifically as follows: First, establish a temperature-compression pressure coupling model: In the formula: F Indicates compressive force. This indicates the flow stress of the aluminum alloy. f Indicates the friction factor; a , b m is a material constant, Q represents the deformation activation energy, and R represents the gas constant. Indicates strain rate. Represents the inverse hyperbolic sine function; L , d These represent the length and width of the connector area, respectively. Based on the current real-time temperature T 0. The target value of extrusion pressure is obtained through a temperature-extrusion pressure coupling model. F m ; Then, based on the temperature deviation Dynamic compensation of extrusion pressure is achieved using a PID controller: In the formula: K p , K i , K d These represent the proportional coefficient, integral coefficient, and derivative coefficient of the PID controller, respectively.
8. The real-time control method for thin plate joining process according to claim 7, characterized in that: The objective function is specifically: In the formula: , These represent the weighting coefficients, which are set according to the actual situation. This represents the amount of pressure adjustment for the i-th time; T ci Indicates the first i The initial extrusion temperature recorded for this time; T best This indicates the historical best temperature.