Quick connection system for aluminum alloy sheets

Abstract

The invention provides a rapid connection system for aluminum alloy sheets, and relates to the field of material connection, the rapid connection system comprises a conveying assembly, a shearing assembly, an auxiliary lifting assembly, a sensing system and a heating device, the conveying assembly is composed of two conveying mechanisms, the shearing assembly is arranged between the two conveying mechanisms, and each conveying mechanism is composed of a plurality of conveying rollers; the shearing assembly comprises an upper shearing head and a lower shearing head, and shearing grooves are formed in the middle of the bottom face of the upper shearing head and the middle of the top face of the lower shearing head correspondingly. The auxiliary lifting assembly is arranged on the outer sides of the two conveying rollers of one conveying mechanism and comprises two auxiliary lifting rollers and a lifting device. The sensing system is arranged corresponding to the shearing assembly. According to the system, rapid and efficient connection between the aluminum alloy sheets can be achieved, real-time monitoring can be conducted through intelligent sensors such as a temperature sensor and a pressure sensor in the connection process, and the problem of connector defects caused by the external environment is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of material connection, and particularly to a rapid connection system for aluminum alloy thin plates. Background Art

[0002] Aluminum and aluminum alloys have advantages such as low density, high specific strength, and good corrosion resistance, and are widely used in fields such as aerospace, automobiles, ships, and electronics. Aluminum alloy thin plates, namely plates with a thickness of about 1-5 mm prepared from aluminum alloys, have the characteristics of light weight, high strength, outstanding corrosion resistance, and excellent thermal and electrical conductivity; however, the welding and connection of aluminum alloys have always been difficult problems hindering the development of the aluminum industry. Due to the nature of aluminum alloys themselves, it is very difficult for aluminum alloys to achieve good welding strength through fusion welding or laser welding like steel. At present, friction stir welding is widely used for aluminum alloys, but the welding efficiency is low and it is not suitable for large-scale rapid production. In the production of aluminum alloy sheet and strip, because laser welding cannot be used, it is impossible to continuously produce without stopping like the endless rolling of steel sheet and strip; aluminum sheet and strip usually "sew" the front and rear aluminum coils together to realize production. However, this "sewing" usually requires stopping for several minutes, and the sewn part is relatively large and needs to be cut off later, resulting in a large amount of material waste.

[0003] Research shows that: Through the shear extrusion connection method, better connection of aluminum alloy thin plates can be achieved, and the connection strength exceeds that of friction stir welding and traditional welding, riveting and other connection methods (for example: Journal of Materials Science & Technology, 2023, 164: 168 - 178). Heating shear extrusion connection can effectively avoid problems such as hot cracks, pores, and softening of the heat affected zone during the welding process of aluminum alloy. It (i.e., heating extrusion connection) achieves metallurgical bonding through shear force and plastic deformation, with high joint strength and good sealing performance. However, due to the difference in the extrusion shrinkage amount of the joint during the extrusion process and the characteristics of the thin thickness of the aluminum alloy thin plate, the overall flatness at the connection during extrusion is poor, and problems such as burrs, flash, or unevenness inevitably occur at the joint, which not only affects the subsequent assembly performance and mechanical properties of the thin plate, but also easily causes scratches and damages to the production line; At the same time, during the heating extrusion connection process of the aluminum alloy thin plate, the plastic deformation of the aluminum alloy thin plate mainly depends on the prior heating and the action of the extrusion shear force, and the heating temperature is extremely susceptible to external environmental influences and problems such as sudden temperature changes (such as a sharp drop in temperature) occur, resulting in rapid hardening of the alloy material and a decrease in the plastic flow ability during the connection process, thereby causing the occurrence of unwelded areas or brittle fractures at the joint, and even a large temperature gradient appears in the thin plate cross-section or joint area, resulting in the generation of thermal stress and ultimately the generation of hot cracks; By increasing the preheating temperature, the influence of sudden temperature changes can be reduced to a certain extent, but it will cause the aluminum alloy to exceed its recrystallization temperature and problems such as brittle fracture of the connection part due to coarse grains occur. If the heating temperature is too high, it will even cause local melting of the aluminum alloy, and the molten aluminum alloy adheres to the surface of the extrusion head, affecting the normal progress of the connection extrusion. In addition, when there is a sudden temperature change and the simultaneous action of the extrusion force (i.e., the temperature-pressure parameters do not match), uneven thickness distribution or warping deformation will occur, which not only affects the dimensional accuracy of the connection, but also affects the overall mechanical properties of the connector, and the connection quality is poor. Summary of the Invention

[0004] Aiming at the problems existing in the above prior art, the purpose of the present invention is to provide a rapid connection system for aluminum alloy thin plates, which can not only achieve rapid and efficient connection between aluminum alloy thin plates, but also can monitor the temperature and extrusion force in real time during the connection process, effectively avoiding the problems of sudden temperature changes caused by external environmental influences and resulting in connector defects.

[0005] The purpose of the present invention is achieved through the following technical solutions: A rapid connection system for aluminum alloy thin plates, 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, and a shearing assembly is arranged between the two sets of conveying mechanisms. Both sets of conveying mechanisms are composed of multiple conveying rollers, and the upper cutting surfaces of the multiple conveying rollers are located on the same horizontal plane. The shearing assembly includes an upper shearing head and a lower shearing head, and shearing grooves are 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 groove of the upper shearing head is mirror-symmetrical with the shearing groove of the lower shearing head (that is, the upper shearing head rotates 180° around its center and is completely consistent with the lower shearing head). The auxiliary lifting assembly is arranged outside 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, 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. The sensing system is arranged corresponding to the shearing assembly.

[0006] Based on the further optimization of the above solution, the shearing groove is composed 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 successively the small arc segment and the large arc segment in the conveying direction of the conveying assembly. The radius of the small arc segment is 3 times the thickness of the aluminum alloy thin plate, and the radius of the large arc segment is 6 times the thickness of the aluminum alloy thin plate.

[0007] Based on the further optimization of the above solution, the length of the shearing groove is not greater than 5 times the thickness of the aluminum alloy thin plate; the lengths of the flat sections on both sides of the shearing groove are the same and greater than 5 times the thickness of the aluminum alloy thin plate.

[0008] Based on the further optimization of the above solution, the sensing system includes an infrared sensor, a temperature sensor and a pressure sensor. The infrared sensor is arranged on one side of the shearing assembly close to the auxiliary lifting assembly, and includes an infrared emission source and an infrared receiving source. The infrared emission source and the infrared receiving source are respectively arranged corresponding to the lower shearing head and the upper shearing head, and the infrared emission source and the infrared receiving source are correspondingly arranged. The temperature sensor is arranged on the bottom surface of the upper shearing head on the side of the corresponding shearing groove close to the auxiliary lifting assembly, and the temperature sensors are uniformly distributed along the width direction of the upper shearing head. The pressure sensor (such as a high-temperature strain gauge sensor) is arranged on the top surface of the lower shearing head on the side of the corresponding shearing groove far from the auxiliary lifting assembly, and the pressure sensors are uniformly distributed along the width direction of the lower shearing head.

[0009] Based on the further optimization of the above solution, the heating device is located on the front and rear sides of the shearing assembly and is arranged corresponding to the overlapping part of the stacked aluminum alloy thin plates. The heating device can realize the clamping of the aluminum alloy thin plates; at the same time, infrared thermal imagers are arranged on the front and rear sides of the shearing assembly and above the heating device, and the line-of-sight directions of the infrared thermal imagers are opposite to the overlapping positions of the aluminum alloy thin plates.

[0010] A rapid connection method for aluminum alloy thin plates, using the above connection system, includes: Step 1. Stacking of aluminum alloy thin plates: Place the aluminum alloy thin plates on the conveying assembly so that the aluminum alloy thin plates move along with 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 shearing head, pause the operation of one side of the conveying mechanism (i.e., the conveying mechanism away from the auxiliary lifting assembly), and place the latter aluminum alloy thin plate on the other conveying mechanism (i.e., the conveying mechanism provided with the auxiliary lifting assembly), and the latter aluminum alloy thin plate moves along with the conveying mechanism; when the end of the latter aluminum alloy thin plate is sensed by the infrared sensor, the corresponding conveying mechanism stops, the auxiliary lifting roller lifts and rotates, realizing the lifting and continuous movement of the latter aluminum alloy thin plate, so that the end of the latter aluminum alloy thin plate moves to the middle of the shearing groove of the upper shearing head. At this time: the auxiliary lifting roller stops running, the upper shearing head moves down until its bottom surface contacts the end face of the latter aluminum alloy thin plate, the upper shearing head pauses running, and then the auxiliary lifting roller descends and resets; Step 2. Heating of aluminum alloy thin plates: First, drive the heating devices on the front and rear sides to operate to form clamping on the stacked aluminum alloy thin plates; then, start the heating devices to heat the aluminum alloy thin plates; after heating is completed, the front and rear heating devices release the clamping on the aluminum alloy thin plates; Step 3. Extrusion connection: Start the upper shearing head and the lower shearing head simultaneously to make them move towards each other to realize the shearing connection of two aluminum alloy thin plates; during the connection process, monitor the temperature and pressure simultaneously to realize pressure compensation and optimization of the heating temperature.

[0011] Based on the further optimization of the above scheme, the diameter of the auxiliary lifting roller is 2 - 4 times the diameter of the conveying roller, and the lifting height of the auxiliary lifting roller is 1 - 3 times the thickness of the aluminum alloy thin plate; in the initial state, the top of the auxiliary lifting roller is located 0.2 - 2 mm below the top of the conveying roller.

[0012] Based on the further optimization of the above scheme, the monitoring of the temperature and pressure in Step 3 to realize pressure compensation and optimization of the heating temperature is specifically as follows: First, predict the temperature of the connection head at the next moment through the law of conservation of energy:

[0013] In the formula: T(t + 1) represents the predicted temperature at the next moment, T(t) represents the temperature at the current moment; Q f represents the heat generated by friction during the extrusion process, Q e represents the heat from external heating, Q l represents the dissipated heat; represents the material density, Ac Denotes the contact area of the connector h Denotes the thickness of the aluminum alloy thin sheet c p Denotes the specific heat capacity of the material; Denotes the time step between the next moment and the current moment; Where:

[0014] In the formula: Denotes the internal friction characteristics of the object; F(t) Denotes the extrusion force function related to time; Denotes the operating speed of the extrusion head changing with time; H c Denotes the convective heat transfer coefficient; T n Denotes the measured temperature of the aluminum alloy thin sheet at the previous moment, T a Denotes the ambient temperature; A l Denotes the heat dissipation area; Denotes the material emissivity; Denotes the Stefan - Boltzmann constant; After that, through the cooperation of the temperature sensor and the infrared thermal imager, the actual temperature of the connector at the next moment is obtained T 0 ; If T 0 and T(t + 1) The deviation between them is greater than the preset deviation threshold (the deviation threshold is specifically set according to the time step), indicating that a temperature mutation occurs during the extrusion process and is compensated by changing the extrusion force; otherwise, it indicates that no temperature mutation occurs; Meanwhile, record the initial temperature, actual temperature, and the regulation amount of the extrusion force (if there is a temperature mutation) during each extrusion process, construct an objective function, and optimize the initial temperature through machine learning.

[0015] Based on the further optimization of the above - mentioned scheme, the method for obtaining the actual temperature of the connector at the next moment is specifically as follows: First, calibrate the material emissivity of the aluminum alloy thin sheet through pre - calibration with a blackbody furnace (since the surface emissivity of aluminum alloy is affected by oxidation degree, roughness, etc., calibration can effectively reduce the errors brought by oxidation degree and roughness):

[0016] In the formula: Denotes the surface radiation luminance of the aluminum alloy; Denotes the blackbody radiation luminance; T Denotes the target temperature; Hp represents the Planck constant; c represents the speed of light; represents the working wavelength of the infrared thermal imager; k represents the Boltzmann constant; Then, according to the brightness difference between the heating area and the background radiation, the infrared thermal imager image is segmented by the Otsu algorithm to extract the initial ROI area; and the Canny operator is used to detect the edge of the heating area, and morphological operations (such as dilation, erosion, etc.) are combined to remove noise to ensure that the ROI area accurately covers the heating area; After that, the measured brightness of each pixel in the ROI area is obtained , and corrections for environmental parameters are made, including reflection radiation correction and atmospheric attenuation correction, Reflection radiation correction:

[0017] In the formula: T a represents the surrounding environmental temperature, and the environmental brightness is obtained by combining the environmental temperature with Planck's law ; Atmospheric attenuation correction:

[0018] In the formula: represents the atmospheric transmittance at a distance of D , that is, the distance between the infrared thermal imager and the aluminum alloy heating area is D ; Using the corrected radiation brightness, the temperature value detected by the corresponding infrared thermal imager is obtained T X :

[0019] Since the infrared thermal imager will detect the heating areas on the front and rear edges of the aluminum alloy thin plate, and the middle heating area is blocked by the upper shear head and the lower shear head, there will be a large deviation in infrared imaging temperature measurement. Therefore, through the cooperation of the temperature sensors evenly arranged on the upper shear head and the detection results of the infrared thermal imager, precise temperature feedback is achieved. Specifically: The temperature sensors on the front and rear sides of the upper shear head are used to obtain the corresponding detected temperatures in real time T c-b , and the temperature is detected by the temperature sensor T c-b and the temperature detected by the infrared thermal imager at the corresponding moment T X , the temperature at each temperature sensor point in the middle of the upper shear head is obtained T c-ni ( i =1,2,…,n-2 The corresponding actual temperature value T x-i , where n represents the number of temperature sensors on the upper shear head:

[0020] Finally, fit the actual temperature values of each point T x-i and T X , which is the actual temperature of the heating area of the aluminum alloy thin plate at the current moment T 0 .

[0021] Based on the further optimization of the above solution, the method for compensating the temperature mutation by extrusion force is specifically as follows: First, establish a temperature-extrusion force coupling model:

[0022] In the formula: F represents the extrusion force, represents the flow stress of the aluminum alloy, f represents the friction factor; a , b , m are material constants (obtained from experimental data, n is usually 0.5 - 2), Q represents the activation energy of deformation, R represents the gas constant, represents the strain rate (determined by the extrusion rate), represents the inverse hyperbolic sine function; L , d respectively represent the length and width of the connector area; Based on the currently real-time acquired temperature T 0 , obtain the target value of the extrusion force through the temperature-extrusion force coupling model F m ; Then, according to the temperature deviation , use the PID controller to achieve dynamic compensation of the extrusion force:

[0023]

[0024] In the formula: K p , K i , K d respectively represent the proportional coefficient, integral coefficient, and differential coefficient of the PID controller.

[0025] Based on the further optimization of the above scheme, the objective function is specifically as follows:

[0026] In the formula: and respectively represent the weight coefficients, which are set according to the actual situation; represents the extrusion pressure adjustment amount at the i-th time; T ci represents the i initial extrusion temperature recorded at the i-th time; T best represents the historical optimal temperature; By constructing an intelligent model (such as: random forest or deep neural network model, etc.), the best initial temperature is predicted, and the input features include ambient temperature, sheet thickness, and historical process parameters.

[0027] The following are the technical effects of the technical solution of the present invention: In the present invention, by heating and extruding the aluminum alloy thin plate, through various forms of heating, extrusion, shearing, and friction, plastic deformation occurs between the aluminum alloy thin plates, and the two metals are tightly connected together through the action of metal bonds; by respectively arranging shear groove structures with double arc segments on the upper shear head and the lower shear head, it can not only provide a buffer space for the connecting head of the plastic deformed aluminum alloy thin plate, avoid the stress concentration point caused by the sudden change of the joint after connection, resulting in low mechanical properties of the joint, but also ensure the smoothness of the surface of the connecting head during the extrusion process, avoid problems such as burrs and flash on the edge of the thin plate due to warping caused by the pressure effect, which are likely to scratch the production line; in addition, the design of the shear groove structure with double arc segments can also enhance the process of rearrangement of metal atoms and grain refinement during extrusion, thereby improving the strength and mechanical properties of the connecting head.

[0028] At the same time, through the real-time monitoring and prediction of the sensing system in the present invention, by establishing a temperature-extrusion pressure coupling model, the sudden change of temperature caused by the external environment is effectively prevented through the compensation of extrusion pressure, thereby avoiding problems such as rapid hardening of the alloy material, reduction of plastic flow ability, thermal cracks caused by extrusion stress, and coarse grains of the alloy due to the molten state, ensuring the plastic deformation ability and recrystallization ability of the aluminum alloy thin plate connection area in a short time, and ensuring the quality and mechanical properties of the connecting head. Description of the Drawings

[0029] Figure 1 is a schematic structural diagram of the aluminum alloy thin plate rapid connection system in the embodiment of the present invention.

[0030] Figure 2 is Figure 1 a partial enlarged view of A in

[0031] Figure 3 is Figure 1 a sectional view taken along the B-B direction of

[0032] Figure 4 a tensile curve diagram after connecting aluminum alloy thin plates by the connection system of the present invention.

[0033] Figure 5 a microstructural diagram of the connection position after connecting aluminum alloy thin plates by the connection system of the present invention.

[0034] Among them, 10 is an aluminum alloy thin plate; 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 receiving source; 412 is an infrared transmitting source; 42 is a temperature sensor; 43 is a pressure sensor; 51 is a heating device; 52 is an infrared thermal imager. Specific embodiments

[0035] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present invention.

[0036] Embodiment 1: A rapid connection system for aluminum alloy thin plates includes a conveying assembly, a shearing assembly, an auxiliary lifting assembly, a sensing system and a heating device 51. The conveying assembly is composed of two conveying mechanisms, and a shearing assembly is arranged between the two conveying mechanisms (as Figure 1 shown). Both of the two conveying mechanisms are composed of multiple conveying rollers 11, and the upper cutting surfaces of the multiple conveying rollers 11 are located on the same horizontal plane (as Figure 1 shown. Two conveying rollers 11 are respectively arranged on the left and right sides of the shearing assembly. The number of conveying rollers 11 on the corresponding side is set according to the actual length of the aluminum alloy thin plate 10. The two conveying rollers 11 in this embodiment are only for illustration and do not 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 (as Figure 1 shown). The shearing groove 20 of the upper shearing head 21 and the shearing groove 20 of the lower shearing head 22 are mirror-symmetrical (that is, the upper shearing head 21 rotates 180° around its center and is completely consistent with the lower shearing head 22, as Figure 1 shown); the shearing groove 20 is composed of two arc segments, including a small arc segment and a large arc segment (as Figure 2 shown). The small arc segment and the large arc segment are smoothly connected, and the shearing groove 20 of the upper shearing head 21 is in the order of the small arc segment and the large arc segment from the conveying direction of the conveying assembly (that is, the direction from left to right as Figure 1 shown). The shearing groove 20 of the lower shearing head 22 is in the order of the small arc segment and the large arc segment from the conveying direction of the conveying assembly, that is,Figure 1 In the left-to-right direction as shown, there is a large arc segment and a small arc segment in sequence. The radius of the small arc segment is 3 times the thickness of the aluminum alloy thin plate 10 (as Figure 2 shown. In this embodiment, it is assumed that the thickness of the aluminum alloy thin plate 10 is h, then the radius of the bq segment is 3h), and the radius of the large arc segment is 6 times the thickness of the aluminum alloy thin plate 10 (that is, the radius of the cq segment is 6h). The length of the shearing groove 20 is not greater than 5 times the thickness of the aluminum alloy thin plate 10 (that is, the length of the bc segment ≤ 5h); the lengths of the flat segments on both sides of the shearing groove 20 are the same (that is, ab = cd, ef = gh) and greater than 5 times the thickness of the aluminum alloy thin plate 10 (that is, ab > 5h). In addition, if the thickness of the aluminum alloy thin plate 10 is less than 1 mm, the lengths of the flat segments on both sides of the shearing groove 20 (that is, the ab segment, ca segment, ef segment, gh segment) are greater than 5 mm.

[0037] The auxiliary lifting assembly is arranged outside the two conveying rollers 11 of a set of conveying mechanisms (that is, Figure 1 the set of conveying mechanisms on the left side as shown), and 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 adopt a conventional hydraulic lifting device in the art. A bracket is arranged at the two ends corresponding to the auxiliary lifting rollers 31, and the two ends of the auxiliary lifting rollers 31 are respectively rotatably connected to the bracket, and a motor for driving the auxiliary lifting rollers 31 is arranged on the bracket).

[0038] The sensing system is arranged corresponding to the shearing assembly. The sensing system includes an infrared sensor, a temperature sensor 42 and a pressure sensor 43. The infrared sensor is arranged on the side of the shearing assembly close to the auxiliary lifting assembly (that is, Figure 1 the left side as shown), and includes an infrared emission source 412 and an infrared receiving source 411. The infrared emission source 412 and the infrared receiving source 411 are respectively arranged corresponding to the lower shearing head 22 and the upper shearing head 21, and the infrared emission source 412 and the infrared receiving source 411 are arranged corresponding to each other (as Figure 1 shown); the temperature sensor 42 is arranged on the bottom surface of the upper shearing head 21 on the side close to the auxiliary lifting assembly corresponding to the shearing groove 20 (that is, Figure 1 the left side corresponding to the shearing groove 20 as shown), and the temperature sensor 42 is evenly distributed along the width direction of the upper shearing head 21 (as Figure 3 shown. The number of the temperature sensors 42 is set corresponding to the actual detection accuracy and the width of the upper shearing head 21); the pressure sensor 43 (for example, a high-temperature strain gauge sensor is adopted) is arranged on the top surface of the lower shearing head 22 on the side far from the auxiliary lifting assembly corresponding to the shearing groove 20 (that is, Figure 1 the right side corresponding to the shearing groove 20 as shown), and the pressure sensor 43 is evenly distributed along the width direction of the lower shearing head 22 (as Figure 3As shown, the pressure sensor 43 is set corresponding to the actual detection accuracy and the width of the lower shear head 22).

[0039] The heating device 51 is located at the front and rear sides of the shearing assembly (i.e., Figure 3 the left and right sides shown), and is set corresponding to the overlapping part of the stacked aluminum alloy thin plates 10 (as Figure 3 shown). The heating device 51 can clamp the aluminum alloy thin plates 10; meanwhile, an infrared thermal imager 52 is arranged above the heating device 51 at the front and rear sides of the shearing assembly, and the line-of-sight direction of the infrared thermal imager 52 is opposite to the overlapping position of the aluminum alloy thin plates 10 (as Figure 3 shown).

[0040] The tensile curve and microstructure after connection using the system in this embodiment are as Figure 4 and Figure 5 shown. Among them, Figure 4 the difference between Process 1 and Process 2 lies in the vertical distance between point b and point g; in the actual process, point b and point g are on a vertical line, and the distance is adjusted according to the plate thickness. In this embodiment, after shearing and extrusion, the vertical distance between point b and point g in Process 1 is 0.8h, while in Process 2 it is 1h at the end.

[0041] Embodiment 2: A rapid connection method for aluminum alloy thin plates, using the connection system as described in Embodiment 1, includes: Step 1. Stacking of aluminum alloy thin plates: Place the aluminum alloy thin plates on the conveying assembly so that the aluminum alloy thin plates follow the operation of the conveying assembly (i.e., the aluminum alloy thin plates 10 run from left to right in the direction as Figure 1 shown through the conveying rollers 11); when the tail of the previous aluminum alloy thin plate 10 is located in the middle of the shearing groove 20 of the lower shear head, pause the operation of one side of the conveying mechanism (i.e., Figure 1 the conveying mechanism on the right side far from the auxiliary lifting assembly shown), that is, pause the advancement of the previous aluminum alloy thin plate 10: The operation pause control of the conveying mechanism on the right side can be carried out through an infrared sensor: When the aluminum alloy thin plate 10 blocks the infrared sensor, the infrared receiving source 411 cannot receive the signal of the infrared transmitting source 412. As the aluminum alloy thin plate 10 continues to be conveyed, the tail of the aluminum alloy thin plate 10 reaches the infrared sensor and continues to run. The signal emitted by the infrared transmitting source 412 is no longer blocked by the aluminum alloy thin plate 10 but is received by the infrared receiving source 411. Start timing from this moment, and use the conveying speed of the conveying rollers 11 v 1 and the distance from the middle of the shearing groove 20 of the lower shear head 22 to the infrared sensor to obtain the operation pause time of the conveying mechanism on the right side t 1 :

[0042] In the formula: l ef is the length of the ef segment, l fg is the length of the fg segment of the shearing groove; And place the latter aluminum alloy thin plate 10 on another conveying mechanism (that is, Figure 1 the conveying mechanism shown with an auxiliary lifting component arranged on the left side), and the latter aluminum alloy thin plate 10 runs following the conveying mechanism; when the end of the latter aluminum alloy thin plate 10 is sensed by the infrared sensor (that is, when there is no latter aluminum alloy thin plate 10, the infrared receiving source 411 continuously receives the signal of the infrared transmitting source 412; when there is a latter aluminum alloy thin plate 10, the infrared transmitting source 412 is blocked, and timing is based on this), the corresponding conveying mechanism stops, the auxiliary lifting roller 31 lifts and rotates, the diameter of the auxiliary lifting roller 31 is 2 - 4 times the diameter of the conveying roller 11 and the lifting height of the auxiliary lifting roller 31 is 1 - 3 times the thickness of the aluminum alloy thin plate 10 (the core shaft part of the auxiliary lifting roller 31 is made of steel pipe or steel bar, and the outer ring is made of flexible materials such as polyurethane and rubber to avoid scratching the aluminum plate); in the initial state, the top of the auxiliary lifting roller 31 is located 0.2 - 2 mm below the top of the conveying roller 11; realize the lifting and continuous operation of the latter aluminum alloy thin plate 10, so that the end of the latter aluminum alloy thin plate 10 runs to the middle of the shearing groove 20 of the upper shearing head 21, and through the conveying speed of the auxiliary lifting roller 31 v 2 and the distance from the middle of the shearing groove 20 of the upper shearing head 21 to the infrared sensor, obtain the time at this moment t 2 :

[0043] In the formula: l bc is the length of the bc segment of the shearing groove of the upper shearing head 21; At this time: the auxiliary lifting roller stops running, the upper shearing head 21 moves down until the bottom surface contacts the end face of the latter aluminum alloy thin plate 10, the upper shearing head 21 pauses running, and then, the auxiliary lifting roller 31 descends and resets; Step Two, heating the aluminum alloy thin plate: First, drive the heating devices 51 on the front and rear sides to run (that is, Figure 3 the heating devices 51 on both sides shown move towards each other) to form clamping on the stacked aluminum alloy thin plates 10; then, start the heating devices 51 to heat the aluminum alloy thin plate 10 (the heating time is about 1 minute and the target temperature is about 400 °C); after heating is completed, the front and rear heating devices 51 release the clamping on the aluminum alloy thin plate 10; Step 3. Extrusion connection: Simultaneously start the upper shear head 21 and the lower shear head 22 (through a hydraulic mechanism), and make them move towards each other to achieve the shear connection of two aluminum alloy thin plates 10; during the connection process, synchronously monitor the temperature and pressure to achieve pressure compensation and heating temperature optimization. Specifically: Step 3-1. Predict the temperature of the connection head at the next moment through the law of conservation of energy:

[0044] In the formula: T(t + 1) represents the predicted temperature at the next moment, T(t) represents the temperature at the current moment; Q f represents the heat generated by friction during extrusion, Q e represents the heat from external heating, Q l represents the dissipated heat; represents the material density, A c represents the contact area of the connection head, h represents the thickness of the aluminum alloy thin plate, c p represents the specific heat capacity of the material; represents the time step between the next moment and the current moment; Among them:

[0045] In the formula: represents the internal friction characteristics of the object; F(t) represents the extrusion force function related to time; represents the operating speed of the extrusion head changing with time; H c represents the convective heat transfer coefficient; T n represents the measured temperature of the aluminum alloy thin plate at the previous moment, T a represents the ambient temperature; A l represents the heat dissipation area; represents the material emissivity; represents the Stefan-Boltzmann constant; Step 3-2. Obtain the actual temperature of the connection head at the next moment through the cooperation of a temperature sensor and an infrared thermal imager T 0 , specifically: Calibrate the material emissivity of the aluminum alloy sheet through pre - calibration of the blackbody furnace (since the surface emissivity of aluminum alloy is affected by oxidation degree, roughness, etc., calibration can effectively reduce the errors brought by oxidation degree and roughness):

[0046] In the formula: represents the radiant luminance of the aluminum alloy surface; represents the blackbody radiant luminance; T represents the target temperature; H p represents Planck's constant; c represents the speed of light; represents the working wavelength of the infrared thermal imager; k represents Boltzmann's constant; Segment the infrared thermal imager image through the Otsu algorithm according to the luminance difference between the heating area and the background radiation (the conventional Otsu algorithm in the field can be used, and no excessive limitation is made in this embodiment), and extract the initial ROI area; and use the Canny operator to detect the edge of the heating area, and combine morphological operations (such as dilation, erosion, etc.) to remove noise to ensure that the ROI area accurately covers the heating area; Obtain the measured luminance of each pixel in the ROI area , and perform corrections for environmental parameters, including reflection radiation correction and atmospheric attenuation correction, Reflection radiation correction:

[0047] In the formula: T a represents the ambient temperature, and the ambient luminance is obtained by combining the ambient temperature with Planck's law ; Atmospheric attenuation correction:

[0048] In the formula: represents the atmospheric transmittance at a distance of D , that is, the distance between the infrared thermal imager and the aluminum alloy heating area is D ; Use the corrected radiant luminance to obtain the temperature value detected by the corresponding infrared thermal imager T X :

[0049] Since the infrared thermal imager will detect the heating areas on the front and rear edges of the aluminum alloy thin plate, and the middle heating area is blocked by the upper and lower shearing heads, there will be a large deviation in infrared imaging temperature measurement. Therefore, the temperature sensors evenly arranged on the upper shearing head cooperate with the detection results of the infrared thermal imager to achieve precise temperature feedback. Specifically: Use the temperature sensors on the front and rear sides of the upper shearing head to obtain the corresponding detected temperatures in real time T c-b and detect the temperature through the temperature sensors T c-b and the temperature detected by the infrared thermal imager at the corresponding moment T X to obtain the temperatures at each temperature sensor point in the middle of the upper shearing head T c-ni ( i = 1,2,…,n-2 ) corresponding actual temperature values T x-i wherein, n represents the number of temperature sensors on the upper shearing head:

[0050] Fit the actual temperature values of each point T x-i and T X (by taking the average value or other similar linear fitting methods for temperature fitting), which is the actual temperature of the heating area of the aluminum alloy thin plate at the current moment T 0 .

[0051] Step 3-3, if T 0 and T(t + 1) the deviation between them is greater than the preset deviation threshold (the deviation threshold is specifically set according to the time step), indicating that a temperature mutation occurs during the extrusion process and is compensated by changing the extrusion force. Specifically: Establish a temperature-extrusion force coupling model:

[0052] In the formula: F represents the extrusion force, represents the flow stress of the aluminum alloy, f represents the friction factor; a 、 b 、m are material constants (obtained from experimental data, n is usually 0.5-2), Q represents the activation energy of deformation, R represents the gas constant, represents the strain rate (determined by the extrusion rate), represents the inverse hyperbolic sine function; L, d respectively represent the length and width of the connector area; Based on the currently obtained real-time temperature T 0 , the target value of the extrusion pressure is obtained through the temperature-extrusion pressure coupling model F m ; According to the temperature deviation , the dynamic compensation of the extrusion pressure is realized by using a PID controller:

[0053]

[0054] In the formula: K p , K i , K d respectively represent the proportional coefficient, integral coefficient, and differential coefficient of the PID controller.

[0055] On the contrary, it indicates that there is no temperature mutation (connection can be carried out according to the established extrusion pressure).

[0056] Step 3-4, record the initial temperature, actual temperature, and the regulation amount of the extrusion pressure during each extrusion process (if there is a temperature mutation), and construct an objective function, specifically:

[0057] In the formula: , respectively represent the weight coefficients, which are set according to the actual situation; represents the extrusion pressure adjustment amount for the i-th time; T ci represents the i th recorded extrusion initial temperature; T best represents the historical optimal temperature; Minimize represents the minimization target; The optimization of the initial temperature is realized through machine learning, that is, by constructing an intelligent model (such as: random forest or deep neural network model, etc.), predicting the best initial temperature, and the input features include environmental temperature, plate thickness, and historical process parameters.

Claims

1. A quick connection system for aluminum alloy sheets, characterized in that: It includes a conveying component, a shearing component, an auxiliary lifting component, a sensing system and a heating device. The conveying component consists of two groups of conveying mechanisms and a shearing component is arranged between the two groups of conveying mechanisms. Both groups of conveying mechanisms are composed of multiple conveying rollers and the upper cut surfaces of the multiple conveying rollers are located in the same horizontal plane. The shearing component includes an upper shearing head and a lower shearing head, and shearing grooves are respectively arranged in the middle of the bottom surface of the upper shearing head and the middle of the top surface of the lower shearing head, and the shearing grooves of the upper shearing head and the lower shearing head are mirror-symmetrical. The auxiliary lifting component is arranged on the outside of two conveying rollers of a group of conveying mechanisms, and includes two auxiliary lifting rollers and a lifting device. The two auxiliary lifting rollers are arranged in parallel and their two ends are respectively connected to the lifting device, and the lifting device is used to control the synchronous lifting and lowering of the two auxiliary lifting rollers. The sensing system is arranged corresponding to the shearing component.

2. The aluminum alloy sheet quick connection system according to claim 1, characterized in that: The shearing groove is composed 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 a small arc segment and a large arc segment in the direction of transmission by the transmission component. 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.

3. An aluminum alloy sheet quick connection system according to claim 1 or 2, characterized in that: The length of the shear 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 shear groove is consistent and greater than 5 times the thickness of the aluminum alloy sheet.

4. An aluminum alloy sheet quick connection system according to claim 1 or 3, characterized in that: The sensing system includes an infrared sensor, a temperature sensor and a pressure sensor. The infrared sensor is arranged on the side of the shearing component close to the auxiliary lifting component, and includes an infrared transmitting source and an infrared receiving source. The infrared transmitting source and the infrared receiving source are respectively arranged corresponding to the lower shearing head and the upper shearing head, and the infrared transmitting source and the infrared receiving source are arranged correspondingly; the temperature sensor is arranged on the bottom surface of the upper shearing head located at the side of the corresponding shearing groove close to the auxiliary lifting component, and the temperature sensor is evenly distributed along the width direction of the upper shearing head; the pressure sensor is arranged on the top surface of the lower shearing head located at the side of the corresponding shearing groove away from the auxiliary lifting component, and the pressure sensor is evenly distributed along the width direction of the lower shearing head.

5. The aluminum alloy sheet quick connection system according to claim 4, characterized in that: The heating device is located on the front and rear sides of the shearing assembly and is arranged corresponding to the overlapping positions of the stacked aluminum alloy sheets. The heating device can clamp the aluminum alloy sheets. At the same time, infrared thermal imagers are arranged on the front and rear sides of the shearing assembly and on the upper side of the heating device. The line of sight of the infrared thermal imager is opposite to the overlapping positions of the aluminum alloy sheets.

6. A connection method using the aluminum alloy sheet quick connection system according to claim 1 or 5, characterized in that: include: Step 1, stacking aluminum alloy sheets: placing the aluminum alloy sheets on the conveying assembly, so that the aluminum alloy sheets follow the conveying assembly; when the tail of the previous aluminum alloy sheet is located in the middle of the shearing groove of the lower shearing head, suspend the operation of one side of the conveying mechanism, and place the next aluminum alloy sheet on the other conveying mechanism, so that the next aluminum alloy sheet follows the conveying mechanism; when the end of the next aluminum alloy sheet is sensed by the infrared sensor, the corresponding conveying mechanism stops, and the auxiliary lifting roller is lifted and rotated to achieve the lifting and continuous operation of the next aluminum alloy sheet, so that the end of the next aluminum alloy sheet runs to the middle of the shearing groove of the upper shearing head, at this time: the auxiliary lifting roller stops running, the upper shearing head moves down to the bottom surface to contact the end surface of the next aluminum alloy sheet, the upper shearing head stops running, and then the auxiliary lifting roller is lowered and reset; Step 2, heating the aluminum alloy thin plates: first, drive the heating devices on the front and rear sides to operate and clamp the stacked aluminum alloy thin plates; then, start the heating devices to heat the aluminum alloy thin plates; after the heating is completed, the front and rear heating devices release the clamping of the aluminum alloy thin plates; Step 3: Extrusion connection: Start the upper shear head and the lower shear head at the same time and make them move toward each other to achieve shear connection of the two aluminum alloy sheets; during the connection process, monitor the temperature and pressure simultaneously to achieve pressure compensation and heating temperature optimization.

7. A method for quickly connecting aluminum alloy sheets according to claim 6, characterized in that: 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.

8. The method for quickly connecting aluminum alloy sheets according to claim 6, characterized in that: In step 3, the temperature and pressure are monitored to achieve pressure compensation and heating temperature optimization as follows: First, the temperature of the connector at the next moment is predicted by the law of conservation of energy: Where: T(t+1) represents the predicted temperature at the next moment, T(t) Indicates the current temperature; Q f Indicates the heat generated by friction during the extrusion process. Q e represents the heat of external heating, Q l Indicates the amount of heat lost; represents the material density, A c Indicates the contact area of ​​the connector. h Indicates the thickness of 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: Where: Indicates the internal friction characteristics of an object; F(t) represents the time-dependent squeezing force function; Indicates the extrusion head running speed varying with time; H c represents the convective heat transfer coefficient; T n Indicates the measured temperature of the aluminum alloy sheet at a certain moment. T a Indicates the ambient temperature; A l Indicates the heat dissipation area; represents the material emissivity; represents the Stefan-Boltzmann constant; Afterwards, the actual temperature of the connector at the next moment is obtained through the cooperation of the temperature sensor and the infrared thermal imager. T 0; if T 0 and T(t+1) If the deviation is greater than the preset deviation threshold, it indicates that a sudden temperature change occurs during the extrusion process and is compensated by a change in the extrusion force; otherwise, it indicates that no sudden temperature change occurs; At the same time, the initial temperature, actual temperature and extrusion force control amount of each extrusion process are recorded, the objective function is constructed, and the initial temperature is optimized through machine learning.

9. The method for quickly connecting aluminum alloy sheets according to claim 8, characterized in that: The method for obtaining the actual temperature of the connector at the next moment is specifically as follows: First, the material emissivity of the aluminum alloy sheet is calibrated by a pre-calibrated blackbody furnace: Where: Indicates the surface radiation brightness of aluminum alloy; Represents the brightness of blackbody radiation; T Indicates the target temperature; H p represents Planck's constant; c represents the speed of light; Indicates the working wavelength of the infrared thermal imager; k represents the Boltzmann constant; Then, according to the brightness difference between the heated area and the background radiation, the infrared thermal image is segmented by the Otsu algorithm to extract the initial ROI area. The Canny operator is used to detect the edge of the heated area, and the morphological operation is combined to remove noise to ensure that the ROI area accurately covers the heated area. After that, get the measured brightness of each pixel in the ROI area , and make corrections to environmental parameters, including reflected radiation correction and atmospheric attenuation correction, Reflected Radiation Correction: Where: T a Indicates the ambient temperature, and obtains the ambient brightness by combining the ambient temperature with Planck's law ; Atmospheric attenuation correction: Where: Indicates the distance D The atmospheric transmittance, that is, the distance between the infrared thermal imager and the aluminum alloy heating area is D ; Use the corrected radiation brightness to obtain the temperature value detected by the corresponding infrared thermal imager T X : The temperature sensors evenly arranged on the upper shear head are coordinated with the detection results of the infrared thermal imager to achieve accurate temperature feedback, specifically: Use the temperature sensors on the front and rear sides of the upper shear head to obtain the corresponding detection temperature in real time T c-b , and detect the temperature through the temperature sensor T c-b The temperature detected by the 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 ) corresponds to the actual temperature value T x-i ,in, n Indicates the number of temperature sensors on the upper shear head: Finally, the actual temperature values ​​of each point are fitted T x-i and T X , which is the actual temperature of the heating area of ​​the aluminum alloy sheet at the current moment T 0.

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