Large-size machine shell machining springback detection method and system and machining method

Abstract

The invention relates to the technical field of detection, in particular to a large-size machine shell processing springback detection method and system and a processing method.The method comprises the steps that a plurality of pressure measuring points are sequentially arranged in the extending direction of a machine shell bending area, a pressure data set acting on the bending area by a bending machine is obtained through pressure sensors arranged at the pressure measuring points, and the pressure data set is analyzed; a plurality of displacement measuring points are sequentially arranged in the extending direction of the bending line of the machine shell, a displacement sensor is arranged corresponding to each displacement measuring point, and a displacement sensor array is formed. Acquiring a first displacement data set and a second displacement data set at the moment of bending pressure release and after enclosure rebound stabilization through the displacement sensor array, and deciding the weight of the first displacement data set according to the analysis result of the pressure data set; and according to the second displacement data set and the first displacement data set weighted by the weight, measuring the bending springback angle of the large-size casing. According to the method and the system, the detection error of the bending springback angle is reduced.

Description

Technical Field

[0001] The present invention relates to the field of detection technology, and in particular to a method, system and processing method for detecting springback during machining of a large-sized casing. Background Art

[0002] Air conditioner casings are usually formed using a bending process. Due to the elastic deformation characteristics of the sheet material itself, rebound will occur after bending. That is, the workpiece will produce a certain degree of reverse deformation after the pressure is released, resulting in a deviation between the actual bending angle of the casing and the theoretical design angle. Accurate detection of this bending rebound angle is of great significance to improving the casing forming accuracy, product assembly consistency, and the smooth progress of subsequent processes.

[0003] However, during the processing of industrial air-conditioning casings, they face unique challenges brought about by the large size (length exceeding 1.5m): when the bending length exceeds 1.5 meters, micron-level elastic bending is prone to occur in the middle of the casing, causing the actual pressure at both ends to be 15% to 30% higher than the theoretical value, forming a "saddle-shaped" pressure distribution, which brings difficulties to the rebound angle measurement. Conventional contact or non-contact measurement errors are large and the reliability is poor. As a result, the actual bending angles at both ends of the casing after bending by the press brake deviate from expectations and exceed the industry tolerance (for example, ±0.5°). This causes a V-shaped gap to appear when the casing is assembled, compromising the IP54 protection level. Summary of the Invention

[0004] To this end, the purpose of the present invention is to overcome the problems of large rebound angle detection error and poor reliability caused by span elastic bending in the existing technology when processing large-size casings, and to provide a large-size casing processing rebound detection method and system, which combines multiple sets of displacement data at the moment of pressure release and after rebound stabilization, and based on weighted processing related to pressure and rebound, more accurately reflects the actual rebound behavior and rebound angle of the casing, improves the rebound angle detection accuracy and reliability, and significantly reduces the rebound angle detection error.

[0005] In the first aspect, in order to solve the above technical problems, the present invention provides a large-size casing processing rebound detection method, comprising: A plurality of pressure measuring points are sequentially arranged along the extending direction of the bending zone of the casing, a pressure data set of the pressure applied by the bending machine to the bending zone is obtained through pressure sensors configured at the pressure measuring points, and the pressure data set is analyzed; A plurality of displacement measurement points are sequentially arranged along the extension direction of the bending line of the housing, and a displacement sensor is configured corresponding to each of the displacement measurement points to form a displacement sensor array; the displacement sensor measures the vertical distance from its light spot in the bending area to the bending line; Acquiring a first displacement dataset at the moment of bending pressure release through the displacement sensor array, and determining a weight of the first displacement dataset based on an analysis result of the pressure dataset; A second displacement data set of the housing after rebound stabilization is obtained through the displacement sensor array, and a bending rebound angle of the large-size housing is measured according to the second displacement data set and the first displacement data set weighted by the weight.

[0006] In one embodiment of the present invention, the weight of the first displacement data set is determined based on the analysis results of the pressure data set, including comparing the bending pressure of the pressure measuring point with the pressure threshold; if the bending pressure of the pressure measuring point is greater than or equal to pressure threshold one and less than or equal to pressure threshold two, then the first displacement data assignment weight of the detection area corresponding to the pressure measuring point is 1; the pressure threshold one is less than pressure threshold two; if the bending pressure of the pressure measuring point is less than pressure threshold one, or greater than pressure threshold two, then the first displacement data assignment weight of the detection area corresponding to the pressure measuring point is less than 1.

[0007] In one embodiment of the present invention, the weight of the first displacement data set is determined based on the analysis results of the pressure data set, including calculating the pressure gradient of adjacent pressure measuring points, where the pressure gradient is the ratio of the pressure difference between adjacent pressure measuring points to the spacing; the larger the pressure gradient, the smaller the weight of the first displacement data of the detection area corresponding to the adjacent pressure measuring point; the smaller the pressure gradient, the greater the weight of the first displacement data of the detection area corresponding to the adjacent pressure measuring point.

[0008] In one embodiment of the present invention, the weight is determined according to the following method: ; in, represents the weight of the i-th detection area; k represents the material sensitivity coefficient; G i represents the pressure gradient of the i-th detection area; G0 represents the reference gradient, which is related to the yield strength and thickness of the casing material.

[0009] In one embodiment of the present invention, the pressure measuring point is embedded in the V-groove inclined surface of the lower die of the bending machine.

[0010] In one embodiment of the present invention, the distance between the center of the pressure measuring point and the bottom of the V-shaped groove is 1.2 to 1.5 times the thickness of the casing.

[0011] In one embodiment of the present invention, the arrangement spacing of the displacement sensors is related to the length of the housing: when the housing length is greater than 1.5 m, the arrangement spacing is ≤100 mm; when the housing length is ≤1.5 m, the arrangement spacing is ≤200 mm.

[0012] In one embodiment of the present invention, measuring the bending springback angle of the large-sized housing according to the second displacement data set and the first displacement data set weighted by the weight includes: For each displacement sensor, the first displacement is weighted using a weight to obtain a weighted first displacement D1; the bending angle is calculated according to the weighted first displacement D1. : ; For each of the displacement sensors, the bending angle D2 is calculated according to the second displacement D2. : ; For each of the displacement sensors, according to the bending angle and bending angle 2 Calculate the springback angle : ; Calculating an average rebound angle of all the displacement sensors to obtain a bending rebound angle of the large-size housing; Among them, the first displacement represents the displacement measured by the displacement sensor at the moment the bending pressure is released; D2 represents the displacement measured by the displacement sensor after the casing rebounds and stabilizes; and L represents the horizontal distance from the displacement sensor to the bending line.

[0013] In the second aspect, based on the same inventive concept, the present invention also provides a large-size casing processing rebound detection system, comprising: A plurality of pressure sensors are sequentially arranged at a plurality of pressure measuring points in the extending direction of the bending zone of the casing, and are used to obtain a pressure data set applied by the bending machine to the bending zone; Multiple displacement sensors are sequentially arranged at multiple displacement measurement points along the extension direction of the bending line of the housing; they are used to obtain a first displacement data set at the moment when the bending pressure is released; and to obtain a second displacement data set after the housing rebounds and stabilizes; the displacement sensors are used to measure the vertical distance from their light spots in the bending area to the bending line; A processor is used to analyze the pressure data set; and to make a decision on the weight of the first displacement data set based on the analysis result of the pressure data set; and to calculate the bending rebound angle of the large-size housing based on the second displacement data set and the first displacement data set weighted by the weight.

[0014] On the third aspect, based on the same inventive concept, the present invention also provides a large-size casing processing method, which detects the bending rebound angle of the large-size casing based on the large-size casing processing rebound detection method, and compensates the bending angle according to the bending rebound angle.

[0015] The above technical solution of the present invention has the following beneficial effects compared with the prior art: The large-size casing processing rebound detection method, system and processing method described in the present invention combine multiple sets of displacement data at the moment of pressure release and after rebound stabilization, and perform weighted processing related to pressure and rebound to more accurately reflect the actual rebound behavior and rebound angle of the casing, improve the rebound angle detection accuracy and reliability, and significantly reduce the rebound angle detection error.

[0016] Among them, in order to address the problem of large rebound angle detection errors caused by uneven pressure distribution due to span elastic bending during the forming process of large-size casings, multiple pressure measuring points and pressure sensors are set in the extension direction of the bending area to comprehensively obtain and analyze the bending pressure distribution, and achieve accurate perception of the actual stress state of each area; the displacement at the moment of bending pressure release is weighted according to the bending pressure distribution, and the rebound angles of different pressure zones are accurately integrated. The final deviation between the rebound angle measurement value and the theoretical value can be reduced to within ±0.3°.

[0017] In response to the sudden pressure changes caused by local screw holes, reinforcing ribs and other structures on the casing, multi-point synchronous monitoring and joint analysis of pressure and displacement can identify and adjust the displacement data weight of the sudden change area, suppress the measurement interference caused by local abnormal force, improve the overall robustness and reliability of the rebound angle detection, and reduce the fluctuation amplitude of the rebound angle calculation results by more than 50%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0019] Figure 1 Flowchart of a method for detecting springback during machining of a large-sized housing according to a preferred embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the large-size casing after molding; Figure 3 A schematic diagram of the configuration of a displacement sensor in a preferred embodiment of the present invention; Figure 4 A flow chart for determining a rebound angle in a preferred embodiment of the present invention; Figure 5 2 is a structural block diagram of a large-size casing processing rebound detection system in a preferred embodiment of the present invention.

[0020] Explanation of the reference numerals in the specification: 10 - bending area; 20 - bending line; 30 - displacement sensor. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0022] The reasons for uneven pressure distribution caused by elastic bending across the region are: Uneven pressure distribution is typically characterized by high pressure at the ends and low pressure in the middle. This is primarily determined by the mechanical properties of the sheet metal contact with the die and the dynamics of the bending process. When the sheet metal is pressed into the V-groove of the die, it bends and deforms at the bend line. Due to the sheet metal's flexibility (especially for thinner or longer sheets), its deformation is not completely rigid, but rather exhibits a "flexing" phenomenon. The ends of the sheet metal (especially those closest to the operating side or the fixture) first contact the V-groove at the start of bending. The die's pressure on these ends directly acts at these points of contact, generating high localized pressure. The middle region then lags behind. Due to the sheet metal's flexibility, this portion may not fully adhere to the V-groove in the initial stages (a slight gap exists), requiring it to be gradually "pressed" into the die as the bending process progresses. Consequently, the pressure in this region increases as the sheet metal bends, but remains lower than at the ends (which are already fully in contact with the die, with direct pressure transfer).

[0023] The fundamental reason for the springback angle detection error caused by uneven pressure distribution is that the differences in the degree of plastic deformation and elastic recovery capacity of different regions of the plate during the bending process are not effectively distinguished, resulting in the inability to truly reflect the local deformation state when calculating the springback angle based on single or averaged displacement data.

[0024] The bending force is concentrated in the high-pressure area, the plastic deformation is more complete, and the internal lattice structure of the plate undergoes more significant dislocation and slip, resulting in a large amount of permanent deformation; although elastic recovery occurs after the external force is released, due to the high proportion of plastic deformation, residual plastic deformation dominates, and the final springback angle is small.

[0025] The plastic deformation in the low-pressure area is insufficient, and only a small amount of permanent deformation occurs inside the plate. Most deformation exists in the form of elastic deformation. After the external force is released, the elastic deformation recovers quickly, resulting in a significant increase in the springback angle.

[0026] Traditional methods do not distinguish between differences in pressure distribution, which will lead to the overestimation of small rebound angles in high-pressure areas and the underestimation of large rebound angles in low-pressure areas. The final calculation results deviate from the true rebound angle distribution, which manifests as the overall rebound angle being underestimated or overestimated, causing detection errors.

[0027] The purpose of the embodiments of the present invention is to solve the problem of large rebound angle detection error and poor reliability caused by uneven pressure distribution due to span elastic bending when processing large-sized casings (industrial air-conditioning casings with a length exceeding 1.5m).

[0028] Example 1: To solve this problem, refer to Figure 1 As shown, an embodiment of the present invention provides a method for detecting springback during machining of a large-sized casing, comprising: S100, sequentially setting a plurality of pressure measuring points along an extending direction of a bending zone of the casing, obtaining a pressure data set of the bending machine acting on the bending zone through pressure sensors configured at the pressure measuring points, and analyzing the pressure data set; S200, sequentially setting a plurality of displacement measurement points along the extension direction of the bending line of the housing, and configuring a displacement sensor corresponding to each displacement measurement point to form a displacement sensor array; the displacement sensor measures the vertical distance from its light spot in the bending area to the bending line; S300, acquiring a first displacement dataset at the moment of bending pressure release through the displacement sensor array, and determining a weight of the first displacement dataset based on an analysis result of the pressure dataset; S400 , obtaining a second displacement data set of the housing after rebound stabilization through the displacement sensor array, and measuring a bending rebound angle of the large-size housing according to the second displacement data set and the first displacement data set weighted by the weight.

[0029] In the specific application scenario, for ease of understanding, refer to Figure 2 The diagram shows the location of the bending zone 10 and bending line 20 of a large-scale casing. Multiple pressure measuring points are evenly spaced along the entire length of the bending zone. A pressure sensor is installed at each pressure measuring point to collect real-time data on the pressure applied by the press brake to the bending zone during the bending process. A piezoresistive pressure sensor with a response time of less than 1ms and a range covering 1.2 times the press brake's maximum pressure can be used. It can be embedded in the V-groove slope of the press brake's lower die. The pressure sensor uploads data to a data acquisition module. By statistically analyzing the data from all pressure measuring points, a pressure distribution curve for each area is derived, including peak pressure, average pressure, pressure gradient, and pressure fluctuation rate.

[0030] Along the bending line of the casing, multiple displacement measurement points are set in sequence, and each displacement measurement point is equipped with a displacement sensor. The displacement sensor can be a laser displacement sensor with a spot diameter of ≤0.3mm and a sampling frequency of ≥500Hz. The displacement sensor transmits a measurement spot to the bending area, and accurately measures the vertical distance from the spot in the bending area to the bending line by receiving the reflected signal, thus forming a real-time monitoring capability for multi-point spatial deformation in the bending area. For details, refer to Figure 3 As shown in the figure, it shows a schematic diagram of the configuration position of the displacement sensor. In the height direction, the axis of the displacement sensor is flush with the V-groove of the lower die of the bending machine; in the horizontal direction, the horizontal distance between the center of the displacement sensor light spot and the bending line is L, and the horizontal distance L is pre-calibrated; the displacement sensor can be fixed on a rigid bracket on the side of the bending machine body, located above or on the side of the casing.

[0031] When the bending machine reaches the set bending pressure, the moment when the bending pressure is released is fed back, and the control system instructs all displacement sensors to synchronously collect displacement data at the moment when the bending pressure is released to obtain a first displacement data set; combined with the pressure distribution analyzed in step S100, different weights are assigned to the first displacement data of each displacement measurement point, so that the data in areas with high pressure or complex structure have less influence on the rebound angle calculation, weakening the interference of data in abnormal or non-critical areas.

[0032] After the shell rebound process is completed and the deformation is stable, the displacement sensor array synchronously collects the second displacement data set again. The bending rebound angle is calculated by combining the displacement changes before and after rebound with the weighted first displacement data to obtain the final rebound angle detection result of the shell.

[0033] It should be noted that rebound stability refers to the final state in which the internal stress distribution and shape of the casing gradually tend to be stable after the bending force is released. It can be determined based on the time window method. Within a fixed time window after the bending force is released, if the standard deviation of the displacement data is less than the standard deviation threshold, the rebound is determined to be stable; the standard deviation threshold can be set to 0.01~0.05mm.

[0034] The large-size casing processing rebound detection method described in the present invention addresses the problem of uneven pressure distribution caused by span elastic bending during the forming process of large-size casings, which leads to large errors in rebound angle detection. By setting multiple pressure measuring points and pressure sensors in the extension direction of the bending zone, the bending pressure distribution is comprehensively acquired and analyzed, and accurate perception of the actual stress state of each area is achieved; the displacement at the moment of bending pressure release is partitioned and weighted according to the bending pressure distribution, and the rebound angles of different pressure zones are accurately integrated. The final deviation between the rebound angle measurement value and the theoretical value can be reduced to within ±0.3°.

[0035] In response to the sudden pressure changes caused by local screw holes, reinforcing ribs and other structures on the casing, multi-point synchronous monitoring and joint analysis of pressure and displacement can identify and adjust the displacement data weight of the sudden change area, suppress the measurement interference caused by local abnormal force, improve the overall robustness and reliability of the rebound angle detection, and reduce the fluctuation amplitude of the rebound angle calculation results by more than 50%.

[0036] Specifically, refer to Figure 2 and 4 As shown, measuring the bending rebound angle of the large-sized housing according to the second displacement data set and the first displacement data set weighted by the weight includes: For each displacement sensor, the first displacement d1 is weighted using a weight to obtain a weighted first displacement D1; the bending angle is calculated according to the weighted first displacement D1. : For each of the displacement sensors, the bending angle is calculated according to the second displacement D2 : ; For each of the displacement sensors, calculate the springback angle based on the first bending angle and the second bending angle : : ; Calculate the average value of the springback angles of all the displacement sensors to obtain the bending springback angle of the large-sized housing; where, d1 represents the displacement measured by the displacement sensor at the moment when the bending pressure is released; D2 represents the displacement measured by the displacement sensor after the housing rebounds stably; L represents the horizontal distance from the displacement sensor to the bending line.

[0037] Based on the above embodiments, determine the weight of the first displacement dataset according to the analysis result of the pressure dataset, including comparing the bending pressure of the pressure measurement point with the pressure threshold; if the bending pressure of the pressure measurement point is greater than or equal to the first pressure threshold and less than or equal to the second pressure threshold, then the weight of the first displacement data corresponding to the detection area of the pressure measurement point is assigned as 1; the first pressure threshold is less than the second pressure threshold; if the bending pressure of the pressure measurement point is less than the first pressure threshold or greater than the second pressure threshold, then the weight of the first displacement data corresponding to the detection area of the pressure measurement point is assigned a value less than 1.

[0038] In a specific application scenario, preset the first pressure threshold P1 and the second pressure threshold P2, satisfying P1 < P2; the first pressure threshold is preset as the minimum pressure threshold, and if it is lower than this value, it is determined as the low-pressure area, and the second pressure threshold is preset as the maximum pressure threshold, and if it is higher than this value, it is determined as the high-pressure area. For example, P1 = 0.8Pavg can be set; P2 = 1.2Pavg; Pavg represents the average pressure.

[0039] For each pressure measurement point, compare the actually measured bending pressure P. If P1 ≤ P ≤ P2, it is considered that the force in this area is moderate and the data is reliable, and the weight of the first displacement data corresponding to the detection area is assigned as 1; if P < P1 or P > P2, it is considered that the force in this area is insufficient or excessive, the data is abnormal or has poor representativeness, and the weight of the corresponding first displacement data is assigned a value less than 1.

[0040] By setting the pressure threshold, effectively screen out the pressure measurement points with moderate force, making the data with a weight of 1 dominant in the entire springback detection, ensuring the authenticity and representativeness of the data. For areas with excessive or insufficient force, lower the weight of the corresponding displacement data to reduce its impact on the overall measurement result, thereby improving the robustness of the detection result.

[0041] Industrial air conditioner casings often feature screw holes or ribbed areas. The pressure distribution in areas with these holes or ribs exhibits an increased pressure gradient compared to areas without these components. This manifests as localized pressure concentration and increased uneven pressure distribution. The presence of screw holes significantly alters the mechanical properties of the casing, creating a stress concentration effect. This can be understood as follows: the edges of the screw holes represent typical bond discontinuities. When the casing is bent under pressure, stress accumulates and concentrates at the edges of the holes, with the maximum stress at the edges reaching 2-3 times the average stress. Furthermore, during bending, the mold's pressure around the screw holes is not evenly distributed due to the holes, resulting in significantly higher pressure at the edges than in areas further away. This contrast between the localized high-pressure area and the surrounding low-pressure areas significantly increases the pressure gradient. This pressure concentration can lead to excessive plastic deformation at the edges of the screw holes, potentially causing cracking and exacerbating springback non-uniformity.

[0042] The rigidity of the ribs is much higher than that of the surrounding flat plate area. During bending, the pressure applied by the mold is preferentially concentrated on the more rigid ribs. Because the ribs are less susceptible to deformation, the pressure has difficulty spreading to the adjacent flexible area, resulting in a significant increase in pressure in the rib area, while the pressure is lower in areas away from the ribs. The pressure distribution exhibits a distinct "rib high, plate low" pattern: peak pressure is concentrated along the ribs, while pressure drops sharply perpendicular to the ribs, forming a steep pressure gradient. The plastic deformation in the rib area is more concentrated, resulting in a smaller springback angle; while the adjacent flexible area experiences insufficient plastic deformation and a larger springback angle, resulting in uneven overall springback.

[0043] The presence of screw holes and reinforcing ribs will significantly aggravate the unevenness of pressure distribution and form a steep pressure gradient. This gradient will lead to excessive concentration of local plastic deformation, which in turn affects the rebound behavior (smaller local rebound), affecting the rebound angle detection error from another perspective.

[0044] The displacement sensor measurement value in the area with large pressure gradient cannot truly reflect the actual rebound situation. The reason is that the displacement sensor can only capture the macroscopic displacement of the surface and cannot distinguish the local difference between plastic deformation and elastic recovery. If the high stress area has excessive plastic deformation, resulting in extremely small elastic recovery, the displacement sensor may misjudge the displacement change due to the enhanced local rigidity (high deformation resistance), resulting in a deviation between the measured value and the actual rebound angle.

[0045] In order to solve this problem, in another embodiment of the present invention, the weight of the first displacement data set is determined based on the analysis results of the pressure data set, including calculating the pressure gradient of adjacent pressure measuring points, where the pressure gradient is the ratio of the pressure difference between adjacent pressure measuring points to the spacing; the larger the pressure gradient, the smaller the weight of the first displacement data of the detection area corresponding to the adjacent pressure measuring point; the smaller the pressure gradient, the greater the weight of the first displacement data of the detection area corresponding to the adjacent pressure measuring point.

[0046] In specific application scenarios, the pressure gradient is the ratio of the pressure difference between adjacent pressure measuring points to the distance between them, representing the rate of change of pressure in space. A high pressure gradient indicates stress concentration in a local area, non-uniform plastic deformation of the casing due to a sudden change in rigidity, and significant spatial variation in elastic recovery. By reducing the weight, the interference of abnormal displacement data in this area on the overall rebound angle calculation is suppressed. A low pressure gradient indicates uniform pressure distribution, continuous plastic deformation of the casing, and minimal spatial variation in elastic recovery. Increasing the weight ensures that stable displacement data fully participates in the calculation.

[0047] Specifically, the weight is determined according to the following method: ; in, represents the weight of the i-th detection area; k represents the material sensitivity coefficient, which is 0.6~0.9 for stainless steel and 0.3~0.5 for aluminum alloy; G i represents the pressure gradient of the i-th detection area; G0 represents the reference gradient, which is related to the yield strength and thickness of the casing material and has a value of 0.5~2MPa / mm.

[0048] It represents the ratio of the actual pressure gradient to the theoretical bending gradient of the material, and directly reflects the degree of local deformation anomaly.

[0049] It should be noted that the bending area is parallel to the extension direction of the bending line, the displacement sensor and the pressure sensor are staggered, and the displacement sensor is arranged between adjacent pressure measuring points, and the pressure sensor is arranged between adjacent displacement measuring points; the area between two adjacent pressure measuring points is the detection area, and the pressure gradient between two adjacent detection points affects the first displacement data weight of the displacement sensor located in its detection area.

[0050] Specifically, the pressure measuring point is embedded in the V-groove slope of the lower die of the press brake. During the bending process, the contact area between the machine housing and the V-groove slope of the lower die bears the greatest pressure (accounting for more than 70% of the total pressure). Embedding the pressure measuring point here allows direct monitoring of the actual pressure in the effective deformation zone, avoiding interference from other areas.

[0051] Based on the above embodiment, the distance between the center of the pressure measuring point and the bottom of the V-groove is 1.2 to 1.5 times the thickness of the housing. This area is the starting point of plastic deformation (where the strain gradient is maximum according to finite element analysis), and placing the pressure measuring point there can provide the earliest detection of material yield. If the distance is too close (<1.2 times), the system is susceptible to interference from stress concentration at the bottom of the groove, while if the distance is too far (>1.5 times), the system loses the ability to monitor the core deformation zone.

[0052] Based on the above embodiment, the spacing of the displacement sensors is related to the length of the housing: when the housing length is greater than 1.5m, the spacing is ≤100mm; when it is ≤1.5m, the spacing is ≤200mm. The longer the housing, the more complex its deformation may be during bending due to factors such as its weight and rigidity, requiring a denser arrangement of displacement sensors for accurate measurement. On the other hand, for a relatively short housing, deformation is relatively simple. Appropriately increasing the sensor spacing can reduce the number of sensors used, while maintaining a certain level of measurement accuracy, thereby reducing costs and workload.

[0053] Example 2: The present invention discloses a large-size housing processing rebound detection system, referring to Figure 5 As shown, the detection system includes, A plurality of pressure sensors are sequentially arranged at a plurality of pressure measuring points in the extending direction of the bending zone of the casing, and are used to obtain a pressure data set applied by the bending machine to the bending zone; Multiple displacement sensors are sequentially arranged at multiple displacement measurement points along the extension direction of the bending line of the housing; they are used to obtain a first displacement data set at the moment when the bending pressure is released; and to obtain a second displacement data set after the housing rebounds and stabilizes; the displacement sensors are used to measure the vertical distance from their light spots in the bending area to the bending line; A processor is used to analyze the pressure data set; and to make a decision on the weight of the first displacement data set based on the analysis result of the pressure data set; and to calculate the bending rebound angle of the large-size housing based on the second displacement data set and the first displacement data set weighted by the weight.

[0054] Embodiment 3: The embodiment of the present invention discloses a method for processing a large-size casing, which detects and obtains the bending rebound angle of the large-size casing based on the large-size casing processing rebound detection method, and compensates the bending angle according to the bending rebound angle.

[0055] The above-mentioned Embodiment 2 and Embodiment 3 have the same inventive concept as Embodiment 1 and have the same technical effects as Embodiment 1, and are not described in detail here.

[0056] In summary, the large-size casing processing rebound detection method, system and processing method described in the present invention combine multiple sets of displacement data at the moment of pressure release and after rebound stabilization, and perform weighted processing related to pressure and rebound, so as to more accurately reflect the actual rebound behavior and rebound angle of the casing, improve the rebound angle detection accuracy and reliability, and significantly reduce the rebound angle detection error.

[0057] Among them, in order to address the problem of large rebound angle detection errors caused by uneven pressure distribution due to span elastic bending during the forming process of large-size casings, multiple pressure measuring points and pressure sensors are set in the extension direction of the bending area to comprehensively obtain and analyze the bending pressure distribution, and achieve accurate perception of the actual stress state of each area; the displacement at the moment of bending pressure release is weighted according to the bending pressure distribution, and the rebound angles of different pressure zones are accurately integrated. The final deviation between the rebound angle measurement value and the theoretical value can be reduced to within ±0.3°.

[0058] In response to the sudden pressure changes caused by local screw holes, reinforcing ribs and other structures on the casing, multi-point synchronous monitoring and joint analysis of pressure and displacement can identify and adjust the displacement data weight of the sudden change area, suppress the measurement interference caused by local abnormal force, improve the overall robustness and reliability of the rebound angle detection, and reduce the fluctuation amplitude of the rebound angle calculation results by more than 50%.

[0059] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for detecting springback during machining of large-size housings, characterized by: include, A plurality of pressure measuring points are sequentially arranged along the extending direction of the bending zone of the casing, a pressure data set of the pressure applied by the bending machine to the bending zone is obtained through pressure sensors configured at the pressure measuring points, and the pressure data set is analyzed; A plurality of displacement measurement points are sequentially arranged along the extension direction of the bending line of the housing, and a displacement sensor is configured corresponding to each of the displacement measurement points to form a displacement sensor array; the displacement sensor measures the vertical distance from its light spot in the bending area to the bending line; Acquiring a first displacement dataset at the moment of bending pressure release through the displacement sensor array, and determining a weight of the first displacement dataset based on an analysis result of the pressure dataset; A second displacement data set of the housing after rebound stabilization is obtained through the displacement sensor array, and a bending rebound angle of the large-size housing is measured according to the second displacement data set and the first displacement data set weighted by the weight.

2. The method for detecting springback during machining of a large-sized housing according to claim 1, wherein: Determine the weight of the first displacement dataset based on the analysis result of the pressure dataset, include, comparing the bending pressure at the pressure measuring point with a pressure threshold; If the bending pressure of the pressure measuring point is greater than or equal to pressure threshold 1 and less than or equal to pressure threshold 2, the weight assigned to the first displacement data of the detection area corresponding to the pressure measuring point is 1; and the pressure threshold 1 is less than the pressure threshold 2; If the bending pressure at the pressure measuring point is less than pressure threshold 1, or greater than pressure threshold 2, the weight assigned to the first displacement data of the detection area corresponding to the pressure measuring point is less than 1.

3. The method for detecting springback during machining of a large-sized housing according to claim 1, wherein: Determine the weight of the first displacement dataset based on the analysis result of the pressure dataset, include, Calculating the pressure gradient between adjacent pressure measuring points, where the pressure gradient is the ratio of the pressure difference between adjacent pressure measuring points to the distance between them; The greater the pressure gradient is, the smaller the weight of the first displacement data of the detection area corresponding to the adjacent pressure measuring point is; The smaller the pressure gradient is, the greater the weight of the first displacement data of the detection area corresponding to the adjacent pressure measuring point is.

4. The method for detecting springback during machining of a large-sized housing according to claim 3, wherein: The weights are determined as follows, ； in, represents the weight of the i-th detection area; k represents the material sensitivity coefficient; G i represents the pressure gradient of the i-th detection area; G0 represents the reference gradient, which is related to the yield strength and thickness of the casing material.

5. The method for detecting springback during machining of a large-sized housing according to claim 2, 3 or 4, wherein: The pressure measuring point is embedded in the V-groove inclined surface of the lower die of the bending machine.

6. The method for detecting springback during machining of a large-sized housing according to claim 5, wherein: The distance between the center of the pressure measuring point and the bottom of the V-shaped groove is 1.2 to 1.5 times the thickness of the casing.

7. The method for detecting springback during machining of a large-sized housing according to claim 1, wherein: The arrangement spacing of the displacement sensors is related to the length of the housing: when the housing length is greater than 1.5m, the arrangement spacing is ≤100mm; when the housing length is ≤1.5m, the arrangement spacing is ≤200mm.

8. The method for detecting springback during machining of a large-sized housing according to claim 1 or 7, wherein: measuring a bending springback angle of the large-sized housing according to the second displacement data set and the first displacement data set weighted by the weight, include, For each of the displacement sensors, weighting the first displacement using a weight to obtain a weighted first displacement D1; Calculate the bending angle according to the weighted first displacement D1 : ; For each of the displacement sensors, the bending angle D2 is calculated according to the second displacement D2. : ; For each of the displacement sensors, according to the bending angle and bending angle 2 Calculate the springback angle : ; Calculating an average rebound angle of all the displacement sensors to obtain a bending rebound angle of the large-size housing; Among them, the first displacement represents the displacement measured by the displacement sensor at the moment the bending pressure is released; D2 represents the displacement measured by the displacement sensor after the casing rebounds and stabilizes; and L represents the horizontal distance from the displacement sensor to the bending line.

9. Large size casing processing rebound detection system, characterized by: include, A plurality of pressure sensors are sequentially arranged at a plurality of pressure measuring points in the extending direction of the bending zone of the casing, and are used to obtain a pressure data set applied by the bending machine to the bending zone; Multiple displacement sensors are sequentially arranged at multiple displacement measurement points along the extension direction of the bending line of the housing; they are used to obtain a first displacement data set at the moment when the bending pressure is released; and to obtain a second displacement data set after the housing rebounds and stabilizes; the displacement sensors are used to measure the vertical distance from their light spots in the bending area to the bending line; a processor, configured to analyze the pressure dataset; and to perform decision processing on the weight of the first displacement dataset based on the analysis result of the pressure dataset; And it is used to calculate the bending rebound angle of the large-sized housing according to the second displacement data set and the first displacement data set weighted by the weight.

10. A method for processing a large-size housing, characterized in that: The large-size casing processing rebound detection method according to any one of claims 1 to 8 is used to detect and obtain the bending rebound angle of the large-size casing, and the bending angle is compensated according to the bending rebound angle.

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