Modularized forming method of high-strength steel water drawing pipe for fire extinguishing aircraft

Abstract

The invention relates to the technical field of steel pipe processing and forming, in particular to a modular forming method of a high-strength steel water drawing pipe for a fire-extinguishing airplane, which comprises the following steps: firstly, acquiring initial surface images of two sides of a 15-5PH steel plate to be processed, determining the surface defect type and the quantity ratio, and determining the main defect type and the temperature difference rolling property of each side according to the surface defect type and the quantity ratio; after temperature difference rolling is carried out according to attributes, rolling surface images on the two sides are obtained, colorimetric analysis is carried out on the high-temperature side, and the rolling images are compared with the initial image; whether rolling is qualified or not is judged according to analysis and comparison results, the bending distance of a bending machine is determined accordingly, and the steel plate is bent towards the low-temperature side to be rolled into a cylinder; and after a plastic core rod is arranged in the initial steel pipe, the initial steel pipe is put into a furnace for heat treatment, and finally the finished water drawing pipe is obtained. The temperature difference rolling method is adopted to solve the problems that the 15-5PH steel water drawing pipe for the fire extinguishing aircraft is difficult to form and large in resilience, and the temperature difference rolling process is analyzed to guarantee the forming precision of the steel pipe.

Description

Technical Field

[0001] This invention relates to the field of steel pipe processing and forming technology, and in particular to a modular forming method for a high-strength steel water intake pipe for firefighting aircraft. Background Technology

[0002] 15-5PH, a martensitic precipitation-hardening stainless steel containing Cr, Ni, and other components, undergoes solution treatment and aging. With martensite as the matrix and the precipitation of nano-reinforcing phases, it possesses high strength (tensile strength ≥1310MPa in H900 state), lightweight properties, and good corrosion resistance. It is widely used in aerospace, petrochemical, and medical device industries, and is often processed into steel pipes. However, processing this material into steel pipes faces significant technical challenges: First, its yield strength in the H900 state reaches 1170MPa, more than five times that of ordinary low-carbon steel. Conventional room-temperature rolling requires enormous external force, easily leading to overload of the rolling mill or material cracking. Second, its elastic modulus is approximately 200GPa, with a springback rate of 5%–8% after bending, requiring repeated reshaping, making dimensional accuracy difficult to control. Third, residual internal stress from previous rolling and cutting processes, when released during pipe rolling, can cause uneven local deformation, resulting in excessive ellipticity of the steel pipe. Conventional processing methods are insufficient to efficiently and effectively complete the forming of this steel pipe.

[0003] Chinese Patent Publication No. CN119115453B discloses a method for stamping and forming a socket-type flexible joint steel pipe, belonging to the field of socket-type pipe forming technology. The method includes the following steps: processing the end of the steel pipe; feeding the steel pipe into a stamping device, inserting a punch into the heated end of the steel pipe, and stamping and flaring one end of the steel pipe; feeding the steel pipe into a leveling device to level the flared end of the steel pipe; feeding the leveled steel pipe into a forming device, forming the socket end through a socket forming mechanism at one end of the forming device, and forming the spigot end through a spigot forming mechanism at the other end of the forming device; and sending the formed steel pipe to an inspection table for inspection, removing burrs from both ends of the steel pipe and grinding it to obtain a socket-type flexible joint steel pipe. The socket-type flexible joint steel pipe stamping and forming method described in this invention can solve the problems of low forming quality and high defect rate of existing socket-type flexible joint steel pipes. Therefore, it can be seen that the existing technology has the following problems:

[0004] When processing high-strength steel such as 15-5PH, the large springback of high-strength steel was not taken into account, which required greater external force, making the machine prone to overload and resulting in low precision and efficiency in steel pipe forming. Summary of the Invention

[0005] Therefore, this invention provides a modular forming method for high-strength steel water intake pipes for firefighting aircraft, which overcomes the problems in the prior art where the high springback of high-strength steel such as 15-5PH is not taken into account when processing it, requiring greater external force, which makes the machine prone to overload and the forming accuracy and efficiency of the steel pipe are not high.

[0006] To achieve the above objectives, the present invention provides a modular molding method for a high-strength steel water intake pipe for firefighting aircraft, comprising:

[0007] Obtain initial surface images of both sides of the 15-5PH steel plate to be processed to determine the corresponding surface defect types and their proportions.

[0008] The main defect type of the initial surface image on the corresponding side is determined based on the surface defect type and its proportion to determine the temperature difference rolling properties of the surface on the corresponding side.

[0009] Based on the temperature difference rolling properties of the two sides of the 15-5PH steel plate to be processed, temperature difference rolling is performed on it to obtain rolling surface images of the two sides of the steel plate.

[0010] Colorimetric analysis was performed on the roll-pressed surface image on the high-temperature side, and the roll-pressed surface image was compared with the initial surface image corresponding to the temperature difference roll pressing.

[0011] The quality of temperature difference roller pressing is determined by combining image comparison results and colorimetric analysis results.

[0012] The bending distance of the bending machine is determined in response to whether the temperature difference pressure roller is qualified, so as to bend the steel plate that has been subjected to temperature difference roller pressing so that the steel plate bends to the low temperature side and rolls into a cylindrical shape;

[0013] Welding is performed at the joints of the cylindrical steel plates, and the welded areas are ground until they are flush with the base material to form the initial steel pipe.

[0014] A plastic mandrel is placed inside the initial steel pipe to form a plastic steel pipe, and the plastic steel pipe is placed in a furnace for heat treatment to obtain the finished water pipe;

[0015] The temperature difference roller pressing properties include a high-temperature side and a low-temperature side.

[0016] As a preferred technical solution for the modular forming method of high-strength steel water intake pipes for firefighting aircraft, the process of determining the corresponding surface defect type based on the initial surface image includes:

[0017] An initial surface image is acquired using a high-definition camera, and the location of defects in the initial surface image is determined.

[0018] The defect sub-maps at each defect location are numbered and sent to the machine learning model to determine the defect type of each defect sub-map;

[0019] Based on the defect type, determine the corresponding surface defect type and the proportion of that surface defect type.

[0020] The surface defect types include defects that benefit plastic deformation and defects that cause severe plastic deformation;

[0021] The defect types corresponding to the beneficial defects of plastic deformation include indentations, shallow pits, and rolling stripes; the defect types corresponding to the malignant defects of plastic deformation include microcracks and hairline cracks.

[0022] As a preferred technical solution for the modular forming method of high-strength steel water intake pipes for firefighting aircraft, the process of determining the main defect type of the corresponding side surface image based on the surface defect type and its proportion includes:

[0023] The determination of whether to combine the quantity ratio with the surface defect type to determine the main defect type is based on the aforementioned surface defect type.

[0024] In response to whether the surface defect type is a beneficial defect for plastic deformation or a malignant defect for plastic deformation, the main defect type is determined without considering the proportion of the defects, and the main defect type is determined to be the surface defect type.

[0025] In response to the surface defect types including beneficial and detrimental plastic deformation defects, the primary defect type is determined by combining the proportion of their quantities. The primary defect type is further determined based on their proportion of quantities.

[0026] If the proportion of beneficial defects in plastic deformation is greater than the proportion of harmful defects in plastic deformation, then the main defect type is determined to be a beneficial defect in plastic deformation.

[0027] If the proportion of beneficial defects in plastic deformation is less than the proportion of malignant defects in plastic deformation, then the main defect type is determined to be a malignant defect in plastic deformation.

[0028] If the proportion of beneficial defects in plastic deformation is equal to the proportion of malignant defects in plastic deformation, then the type of unclaimed defect is determined.

[0029] As a preferred technical solution for the modular forming method of high-strength steel water suction pipes for firefighting aircraft, the process of determining the temperature difference rolling properties of the two side surfaces based on the main defect types of the two side surfaces includes,

[0030] Determine the main defect types on both sides of the 15-5PH steel plate to be processed;

[0031] The temperature difference rolling properties of the two surfaces are determined based on whether the main defect types are the same, including:

[0032] If the main defect types are different, the temperature difference roll pressing attribute of the corresponding side surface of the malignant plastic deformation defect is determined to be the low temperature side, and / or, the temperature difference roll pressing attribute of the corresponding side surface of the beneficial plastic deformation defect is determined to be the high temperature side.

[0033] If the main defect types are the same, the temperature difference rolling properties of the two surfaces are determined according to the main defect types and their proportions, wherein:

[0034] If all the main defect types are malignant plastic deformation defects, then the side with the higher proportion of defects is the low temperature side in terms of temperature difference rolling.

[0035] If all the main defect types are defects that are beneficial to plastic deformation, then the side with the higher proportion of defects is the high-temperature side in terms of temperature difference rolling properties.

[0036] If all the main defect types are of the no-main-defect type, then the temperature difference rolling properties of the two sides are randomly determined.

[0037] As a preferred technical solution for the modular forming method of high-strength steel water suction pipes for firefighting aircraft, the process of performing colorimetric analysis on the roll-pressed surface image on the high-temperature side includes:

[0038] The high-temperature side of the roller pressing surface image is divided into several roller pressing sub-images, and several pixels are randomly selected from each roller pressing image as feature pixels;

[0039] The chromaticity values ​​of each of the aforementioned feature pixels are determined to determine their average, maximum, and minimum chromaticity values;

[0040] The maximum deviation value is determined based on the maximum chromaticity value and the average value, and the minimum deviation value is determined based on the minimum chromaticity value and the average value.

[0041] The chromaticity fluctuation is determined based on the maximum deviation value, the minimum deviation value, and the average value.

[0042] The colorimetric analysis results are determined based on the relationship between the colorimetric fluctuation amount and the preset fluctuation amount.

[0043] The colorimetric analysis results include colorimetric uniformity results and colorimetric non-uniformity results.

[0044] As a preferred technical solution for the modular forming method of high-strength steel water suction pipes for firefighting aircraft, the process of comparing the rolled surface image with the initial surface image before temperature difference rolling includes:

[0045] The percentage of beneficial defects in plastic deformation is determined based on the roll-pressed surface images of each side surface;

[0046] Compare the proportion of the number of beneficial defects of plastic deformation in the initial surface image and the roll-pressed surface image of each side surface, and determine the image comparison result according to the comparison result, including:

[0047] If the comparison result meets the recovery condition, it is determined that the image comparison result is a benign roll press;

[0048] If the comparison result does not meet the recovery condition, it is determined that the image comparison result is a malignant roll press;

[0049] Among them, the recovery condition is that the proportion of the number of beneficial defects of plastic deformation in the roll-pressed surface image is less than or equal to the proportion of the number of beneficial defects of plastic deformation in the corresponding initial surface image.

[0050] As a preferred technical solution of the modular forming method of the water suction pipe made of high-strength steel for fire-fighting aircraft, determine whether the temperature difference roll press is qualified by combining the image comparison result and the chromaticity analysis result. Among them,

[0051] Based on the image comparison result being a benign roll press and the chromaticity analysis result being a uniform chromaticity result, it is determined that the temperature difference roll press is qualified.

[0052] As a preferred technical solution of the modular forming method of the water suction pipe made of high-strength steel for fire-fighting aircraft, determine the bending distance of the bending machine in response to whether the temperature difference roll press is qualified, including,

[0053] In response to the temperature difference roll press being qualified, determine the bending distance of the bending machine as the default distance;

[0054] In response to the temperature difference roll press being unqualified, determine that the bending distance of the bending machine is less than the default distance.

[0055] As a preferred technical solution of the modular forming method of the water suction pipe made of high-strength steel for fire-fighting aircraft, the outer diameter of the plastic core rod is the same as the designed inner diameter of the water suction pipe.

[0056] Compared with the prior art, the beneficial effects of the present invention are as follows. The present invention determines defects and roll press attributes through image analysis, reduces additional defects through targeted temperature difference roll press, ensures the qualification of roll press through image comparison and chromaticity analysis, and the subsequent bending, welding and heat treatment work together to greatly improve the dimensional accuracy and mechanical properties of the water suction pipe, meeting the high-strength requirements of fire-fighting aircraft; the temperature difference roll press reduces the forming resistance of 15-5PH steel, reduces the risk of roll press overload, eliminates the need for repeated shape correction, and shortens the forming cycle; reasonably matching the roll press attributes reduces material waste, and the built-in plastic core rod avoids heat treatment deformation rework, reducing production costs; it conforms to the high-strength and corrosion-resistant characteristics of 15-5PH steel, and the formed water suction pipe can adapt to the high-pressure water transmission and complex working conditions of fire-fighting aircraft, such as resisting corrosion by water media and withstanding the pressure during water suction, ensuring the stable progress of fire-fighting operations.

[0057] In particular, the present invention provides reliable data support for the subsequent matching of temperature difference rolling properties by statistically analyzing the types and proportions of surface defects. The entire process follows a standardized machine vision inspection procedure, requiring no manual intervention from image acquisition to quantity proportion statistics, thus avoiding the problems of low efficiency, missed judgments, and misjudgments in manual inspection. At the same time, adaptive cutting of sub-images and automatic model recognition shorten the defect judgment cycle, creating conditions for the rapid connection of subsequent temperature difference rolling, bending, and other processes, and helping to promote the efficient progress of the entire water pipe forming process. By accurately distinguishing between beneficial and malignant defects and statistically analyzing their proportions, targeted rolling strategies can be formulated. For example, the side with a high proportion of beneficial defects can be set as the high-temperature side to utilize its plasticity to improve the defects, avoiding improper rolling due to inaccurate defect judgment and reducing material scrap. Moreover, the unified defect judgment standard can ensure the consistency of defect analysis results of different batches of steel plates, ensuring the stable quality of the final water pipe and meeting the high-quality requirements of fire-fighting aircraft for water pipes.

[0058] In particular, by directionally matching the main defect type with the rolling properties, misjudgments such as using high temperature (causing crack propagation) for the malignant defect side and low temperature (unable to improve the defect) for the beneficial defect side are avoided. The side with dense microcracks is designated as the low temperature side, which can reduce the probability of microcrack propagation during temperature difference rolling. At the same time, the indentation side is designated as the high temperature side, which improves the indentation improvement rate and directly reduces the defect rate of the formed steel pipe. The constructed judgment rule of single type directly determining and mixed type according to proportion does not require complex parameter calculation and can quickly output the rolling property results, which can adapt to the continuous processing rhythm of the production line. At the same time, the logic of benchmark reverse matching when there is no main defect type and proportion sorting when the same type is used covers all defect distribution scenarios, avoiding judgment failure due to scenario omission and improving the technical versatility. Through standardized judgment logic, it is ensured that 15-5PH steel plates of different batches and different defect distributions can be matched with rolling properties according to unified rules, without affecting the final forming accuracy, ensuring the consistency of water pipes in mass production in terms of strength, roundness and other indicators, which meets the high reliability requirements of fire-fighting aircraft for water pipes.

[0059] In particular, this invention uses a combination of partitioned sampling and quantitative calculation to accurately identify whether the oxidation on the high-temperature side is uniform, thus achieving precise control over the uniformity of oxidation on the high-temperature side. By comparing the proportion of beneficial defects before and after rolling, the effect of temperature difference rolling can be intuitively verified. For the high-pressure water conveyance and fatigue resistance requirements of the water intake pipe, colorimetric analysis ensures uniform oxidation and prevents water leakage, image comparison ensures that defects do not worsen and prevents breakage, and the standardized process also ensures consistent testing across different batches, making the water intake pipe meet aviation-grade standards and reducing the risk of failure of flight fire extinguishing equipment. Attached Figure Description

[0060] Figure 1 This is a step diagram illustrating the modular molding method of a high-strength steel water suction pipe for firefighting aircraft according to an embodiment of the present invention;

[0061] Figure 2This is a flowchart illustrating the process of determining the temperature difference rolling properties of the two surfaces in an embodiment of the present invention.

[0062] Figure 3 This is a flowchart illustrating colorimetric analysis in an embodiment of the present invention. Detailed Implementation

[0063] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0064] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0065] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0066] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0067] It should be understood that, based on the characteristics of 15-5PH steel having high yield strength and high elastic modulus, the present invention performs temperature difference roll forming on the steel plate to be made into a steel pipe. Taking advantage of the fact that the higher the metal temperature, the better the plasticity and the lower the yield strength, the steel plate is rolled with rollers at different temperatures on both sides. This makes the plasticity of the steel plate on the high-temperature side higher than that on the low-temperature side, and the yield strength lower than that on the low-temperature side. This results in a difference in deformation between the two sides due to the temperature difference, i.e., the high-temperature side is easy to deform and the low-temperature side is difficult to deform. The steel plate has a tendency to actively bend towards the side with greater deformation resistance (i.e., the low-temperature side), thereby reducing the number of bending times when the 15-5PH steel plate is made into a steel pipe and improving the qualification rate of the steel pipe. In addition, it also shortens the steel pipe processing cycle and increases the surface quality of the formed steel pipe.

[0068] Furthermore, this invention determines the high-temperature and low-temperature sides during roll forming based on the defects on both sides of the 15-5PH steel plate to be processed: high-temperature roll forming makes the material more fluid, and after plastic extension to fill shallow pits or flatten protrusions, minor indentations or shallow pit defects can be eliminated or reduced through the fit of the roll surface. At the same time, high-temperature roll forming can utilize its good plasticity to make the surface tend to be flat and reduce the thickness difference through appropriate extension, and redistribute the material according to the roll surface contour when the stress is low, reducing the depth of rolling stripes, balancing the thickness, and reducing the overall internal stress. On the other hand, the low-temperature side has insufficient plasticity but strong rigidity, and is not easily deformed excessively under stress. If there are microcracks, hairline cracks, or potential cracks detected by flaw detection on one side of the steel plate, low-temperature roll forming can prevent the cracks from expanding due to excessive plastic deformation. Low-temperature roll forming can reduce the shedding of impurities or the peeling of brittle layers by means of lower deformation, maintaining surface integrity. By selecting the high-temperature and low-temperature sides and roll forming, beneficial defects on the surface of the steel pipe are reduced, and the surface quality of the product is increased.

[0069] Please see Figure 1 The diagram shows the steps of a modular molding method for a high-strength steel water intake pipe for a firefighting aircraft according to an embodiment of the present invention. The present invention provides a modular molding method for a high-strength steel water intake pipe for a firefighting aircraft, comprising:

[0070] Step S1: Obtain initial surface images of both sides of the 15-5PH steel plate to be processed to determine the corresponding surface defect types and their proportions.

[0071] Step S2: Determine the main defect type of the initial surface image on the corresponding side based on the surface defect type and its quantity ratio to determine the temperature difference rolling properties of the corresponding side surface;

[0072] Step S3: Based on the temperature difference rolling properties of the two sides of the 15-5PH steel plate to be processed, perform temperature difference rolling and obtain rolling surface images of the two sides of the steel plate; in practice, the temperature difference between the two sides during temperature difference rolling is usually controlled between 200℃ and 300℃ (preferably, 400℃ on the high temperature side and 100℃ to 200℃ on the low temperature side) to avoid excessive temperature difference leading to thermal stress superposition;

[0073] Step S4: Perform colorimetric analysis on the roller-pressed surface image on the high-temperature side, and compare the roller-pressed surface image with the initial surface image corresponding to the temperature difference roller pressing.

[0074] Step S5: Determine whether the temperature difference roller pressing is qualified by combining the image comparison results and the colorimetric analysis results;

[0075] Step S6: In response to whether the temperature difference pressure roller is qualified, determine the bending distance of the bending machine to bend the steel plate that has been treated by the temperature difference roller so that the steel plate bends to the low temperature side and rolls into a cylindrical shape.

[0076] Step S7: Weld the joint of the cylindrical steel plate and grind the welded area until it is flush with the base material to form the initial steel pipe.

[0077] Step S8: A plastic mandrel is placed inside the initial steel pipe to form a plastic steel pipe, and the plastic steel pipe is placed in a furnace for heat treatment to obtain the finished water pipe;

[0078] The temperature difference roller pressing properties include a high-temperature side and a low-temperature side.

[0079] It should be understood that this invention acquires initial surface images of both sides of a 15-5PH steel plate, identifies the types and proportions of surface defects, determines the main defect type, and matches the temperature difference rolling properties based on the defect characteristics: the side containing defects such as microcracks that are easily aggravated by high temperatures is designated as the low-temperature side, and the side containing defects such as slight indentations that can be improved by high temperatures is designated as the high-temperature side, laying the foundation for precise rolling; utilizing the characteristic that the higher the temperature of 15-5PH steel, the better the plasticity and the lower the yield strength, the temperature difference is controlled between 200℃ and 300℃, the high-temperature side reduces deformation resistance and is easier to shape, and the low-temperature side maintains... Rigidity control of the direction reduces the superposition of thermal stress. At the same time, image comparison and color analysis are used to determine whether the rolling is qualified, ensuring the quality of rolling. Based on the qualified results of temperature difference rolling, the bending distance of the bending machine is determined. Taking advantage of the characteristic that the steel plate bends to the low temperature side after temperature difference rolling, it is precisely bent and rolled into a cylindrical shape to ensure the roundness of the steel pipe. The cylindrical steel plate joint is welded and ground flat to form the initial steel pipe. An internal plastic mandrel is inserted to prevent the steel pipe from deforming during heat treatment. Then, it undergoes in-furnace heat treatment. Combined with the age strengthening characteristics of 15-5PH steel, the mechanical properties of the steel pipe are improved, and finally qualified finished water pipe is obtained.

[0080] Specifically, in step S1, the process of determining the corresponding surface defect type based on the initial surface image includes:

[0081] Step S11: Use a high-definition camera (an industrial high-definition camera with a resolution of ≥5 million pixels) to acquire a high-definition initial surface image and determine the location of defects in the initial surface image.

[0082] Step S12: Number the defect sub-maps at each defect location and send them to the machine learning model to determine the defect type of each defect sub-map; it should be understood that a single defect sub-map should contain the corresponding complete defect shape;

[0083] In implementation, machine vision detection technology is preferably used, combined with image acquisition, preprocessing, defect identification and localization, and sub-image numbering to complete steps S11 and S12: First, noise is eliminated and defect features are enhanced; second, a defect segmentation and localization method based on region growing is used, with the defect edge points obtained by edge detection as seed points, and a gray level difference threshold (≤15 gray levels) is set. Adjacent similar gray level regions are gradually merged until a complete defect region is segmented. The coordinates of the upper left corner (x1, y1) and lower right corner (x2, y2) of the defect region are calculated using the minimum bounding rectangle algorithm to determine the specific location of the defect in the image, and the area, perimeter, and other parameters of the defect region are recorded; then, based on the bounding box coordinates obtained from defect localization, the original high-definition image is cropped to generate a defect sub-image containing only a single defect (the sub-image size is adaptive according to the defect size); finally, it is sent to a pre-trained machine learning model to determine the defect type;

[0084] In practice, at least one thousand defect samples are used to train the machine learning model;

[0085] Step S13: Determine the corresponding surface defect type based on the defect type, and determine the proportion of the number of that surface defect type. It can be understood that the proportion is the ratio of the number of the corresponding surface defect type to the total number of defect types. In practice, the machine learning model can only determine the defect type based on each defect sub-image, and then determine which surface defect type it belongs to based on the specific defect type. Therefore, the proportion of the number of surface defect types only includes the proportion of beneficial plastic deformation defects and the proportion of malignant plastic deformation defects, and the sum of their proportions is 1.

[0086] The surface defect types include defects that benefit plastic deformation and defects that cause severe plastic deformation;

[0087] The defect types corresponding to the beneficial defects of plastic deformation include indentations, shallow pits, and rolling stripes; the defect types corresponding to the malignant defects of plastic deformation include microcracks and hairline cracks.

[0088] Please see Figure 2 The diagram shows a flowchart illustrating the determination of the temperature difference rolling properties of the two side surfaces according to an embodiment of the present invention. Specifically, in step S2, the process of determining the main defect type of the corresponding side surface image based on the surface defect type and its proportion includes:

[0089] The determination of whether to combine the quantity ratio with the surface defect type to determine the main defect type is based on the aforementioned surface defect type.

[0090] In response to whether the surface defect type is a beneficial defect for plastic deformation or a malignant defect for plastic deformation, the main defect type is determined without considering the proportion of the defects, and the main defect type is determined to be the surface defect type.

[0091] In response to the surface defect types including beneficial and detrimental plastic deformation defects, the primary defect type is determined by combining the proportion of their quantities. The primary defect type is further determined based on their proportion of quantities.

[0092] If the proportion of beneficial defects in plastic deformation is greater than the proportion of harmful defects in plastic deformation, then the main defect type is determined to be a beneficial defect in plastic deformation.

[0093] If the proportion of beneficial defects in plastic deformation is less than the proportion of malignant defects in plastic deformation, then the main defect type is determined to be a malignant defect in plastic deformation.

[0094] If the proportion of beneficial defects in plastic deformation is equal to the proportion of malignant defects in plastic deformation, then the type of unclaimed defect is determined.

[0095] It should be understood that, based on the statistics of beneficial plastic deformation defects, malignant plastic deformation defects, and their proportions in step S1, a two-layer logic of classification and proportion-assisted judgment is constructed. For a single defect type scenario, if only beneficial plastic deformation defects (such as only indentations or shallow pits) or only malignant plastic deformation defects (such as only microcracks or hairline cracks) exist on a certain side of the steel plate, the single defect type is directly defined as the main defect type on that side without relying on the proportion. For a mixed defect type scenario, if two types of defects exist on a certain side at the same time, the proportion is used as the basis for judgment. The defect type with the higher proportion becomes the main defect type, and when the proportions are equal, it is determined to be a type without a main defect.

[0096] Specifically, in step S2, the process of determining the temperature difference rolling properties of the two surfaces according to the main defect types of the two surfaces includes,

[0097] Step S21: Determine the main defect types on both sides of the 15-5PH steel plate to be processed;

[0098] Step S22, determining the temperature difference rolling properties of the two surfaces based on whether the main defect types are the same, includes:

[0099] If the main defect types are different, the temperature difference roll pressing attribute of the corresponding side surface of the malignant plastic deformation defect is determined to be the low temperature side, and / or, the temperature difference roll pressing attribute of the corresponding side surface of the favorable plastic deformation defect is determined to be the high temperature side. It can be understood that if there is a side surface without a main defect type, the high temperature side / low temperature side is determined according to the main defect type of the other side surface, and then the temperature difference roll pressing attribute of this side surface is determined. In one implementation, if the main defect types of the two sides of the steel plate are the no-main-defect type and the malignant plastic deformation defect, the side with the malignant plastic deformation defect is first determined to be the low temperature side, and then the side with the no-main-defect type is determined to be the high temperature side.

[0100] If the main defect types are the same, the temperature difference rolling properties of the two surfaces are determined according to the main defect types and their proportions, wherein:

[0101] If all the main defect types are malignant plastic deformation defects, then the side with the higher proportion of defects is the low temperature side in terms of temperature difference rolling.

[0102] If all the main defect types are defects that are beneficial to plastic deformation, then the side with the higher proportion of defects is the high-temperature side in terms of temperature difference rolling properties.

[0103] If all the main defect types are of the no-main-defect type, then the temperature difference rolling properties of the two sides are randomly determined.

[0104] It should be understood that, in combination with the material characteristics of 15-5PH steel plate, which has good plasticity on the high-temperature side and is easy to improve beneficial defects, and strong rigidity on the low-temperature side and can suppress the deterioration of malignant defects, as well as the need for temperature difference roll forming to directionally avoid defect risks and strengthen the forming advantages, the correspondence between defect type and roll forming attribute is established: (1) When the main defect types on both sides are different, the principle of prioritizing the avoidance of malignant defects is followed. The malignant defect side of plastic deformation is defined as the low-temperature side (using low-temperature rigidity to suppress the propagation of microcracks), and the beneficial defect side of plastic deformation is defined as the high-temperature side (using high-temperature plasticity to improve indentations and shallow pits); if one side has no main defect type, the main defect type on the other side is used as the benchmark. Reverse matching (if the other side is a malignant defect, then this side is the high temperature side) to ensure that the defect-free side is adapted to the rolling demand of the defective side; (2) When the main defect types on both sides are the same: ① When both are malignant defects: the malignant defects on the side with a higher proportion of quantity are more concentrated and require stronger rigid constraints, so it is designated as the low temperature side to reduce the overall crack risk; when both are beneficial defects: the beneficial defects on the side with a higher proportion of quantity are more concentrated and require more plastic deformation space, so it is designated as the high temperature side to maximize the use of high temperature to improve defects; when both are without main defect types: the defects on both sides are evenly distributed and there is no dominant type, so there is no special constraint on the rolling properties, so random matching does not affect the molding effect.

[0105] Please see Figure 3 The diagram shows a flowchart of colorimetric analysis according to an embodiment of the present invention. Specifically, in step S4, the process of performing colorimetric analysis on the roll surface image on the high-temperature side includes:

[0106] Step S411: Divide the high-temperature side roll-pressed surface image into several roll-pressed sub-images and randomly select several pixels as feature pixels in each roll-pressed sub-image. In practice, the manufacturing precision is determined according to the application location and field of the finished water pipe, and then the number of roll-pressed sub-images is determined. It can be understood that the higher the manufacturing precision, the more roll-pressed images there are and the more pixels are selected in each roll-pressed image. In this embodiment of the invention, the finished water pipe is used on a fire-fighting aircraft, and its manufacturing precision is high. Therefore, the number of roll-pressed images is at least 100, and at least 10 feature pixels are selected in each roll-pressed image. That is, the roll-pressed surface image is divided into at least 100 roll-pressed images, and 10 feature pixels are randomly selected in each roll-pressed image.

[0107] Step S412: Determine the chromaticity value of each feature pixel to determine its average value, maximum chromaticity value, and minimum chromaticity value; in practice, the chromaticity value of a single pixel is the sum of the values ​​of the three channels of the RGB channel;

[0108] Step S413: Determine the maximum deviation value based on the maximum chromaticity value and the average value, and determine the minimum deviation value based on the minimum chromaticity value and the average value; in practice, the maximum deviation value is the difference between the maximum chromaticity value and the average value, and the minimum deviation value is the absolute value of the difference between the minimum chromaticity value and the average value.

[0109] Step S414: Determine the chromaticity fluctuation amount based on the maximum deviation value, the minimum deviation value, and the average value; in practice, the sum of 0.5 times the minimum deviation value and the maximum deviation value is determined as the fluctuation deviation value, and the ratio of the fluctuation deviation value to the average value is determined as the chromaticity fluctuation amount; the chromaticity fluctuation amount represents the fluctuation of the chromaticity value of each pixel.

[0110] Step S415: Determine the colorimetric analysis result based on the relationship between the colorimetric fluctuation amount and the preset fluctuation amount. In practice, the preset fluctuation amount is usually 0.05 to 0.1, preferably set to 0.08. If the colorimetric fluctuation amount is greater than the preset fluctuation amount, it indicates that the colorimetric fluctuation of each pixel is relatively large, that is, the color of the high-temperature side surface is not uniform, so the colorimetric analysis result is a colorimetric non-uniform result. If the colorimetric fluctuation amount is less than or equal to the preset fluctuation amount, it indicates that the colorimetric fluctuation of each pixel is relatively small, that is, the color of the high-temperature side surface is relatively uniform, so the colorimetric analysis result is a colorimetric uniform result.

[0111] The colorimetric analysis results include colorimetric uniformity results and colorimetric non-uniformity results.

[0112] It should be understood that, based on the strong correlation between the degree of oxidation and chromaticity value on the high-temperature side of 15-5PH steel plates, quantitative detection of oxidation uniformity is achieved through the logic of partitioned sampling, quantitative calculation, and threshold judgment. According to the high manufacturing precision requirements of fire-fighting aircraft water pipes, the roll-pressed surface image is divided into ≥100 roll-pressed sub-images (covering the entire surface without omission). ≥10 feature pixels are randomly selected from each sub-image to ensure that the sampling points have both global representativeness and statistical significance, avoiding the influence of local anomalies (such as a single dirt spot) on the overall judgment. The sum of the RGB three-channel values ​​is used as the chromaticity value of a single pixel (the thicker the oxidation, the smaller the RGB sum). By calculating the average, maximum, and minimum chromaticity values, basic data on chromaticity distribution is established. Then, the difference between extreme values ​​and the mean is quantified through the maximum and minimum deviation values. Finally, the chromaticity fluctuation represents the oxidation uniformity on the high-temperature side, meeting the requirement that uneven oxidation is a core risk on the high-temperature side.

[0113] Specifically, in step S4, the process of comparing the rolled surface image with the initial surface image before temperature difference rolling includes:

[0114] Step S421: Determine the percentage of beneficial defects in plastic deformation based on the roll-pressed surface images of each side surface;

[0115] Step S422: Compare the proportion of favorable defects in plastic deformation between the initial surface image and the roll-pressed surface image of each side surface, and determine the image comparison result based on the comparison result, including:

[0116] If the comparison results of at least one surface meet the recovery conditions, the image comparison result is determined to be benign rolling.

[0117] If the comparison results of both sides of the surface do not meet the recovery conditions, the image comparison result is determined to be a malignant rolling.

[0118] The recovery condition is that the proportion of beneficial defects in the plastic deformation of the rolled surface image is less than or equal to the proportion of beneficial defects in the plastic deformation of the corresponding initial surface image.

[0119] It should be understood that, based on the goal of improving beneficial defects in plastic deformation through temperature difference rolling, a unidirectional optimization judgment logic is constructed with the proportion of beneficial defects in plastic deformation as the core indicator: the proportion of beneficial defects (indentations, shallow pits, etc.) in plastic deformation on both sides of the steel plate before and after rolling is counted separately, focusing on whether beneficial defects are reduced; the recovery condition is set as the proportion of beneficial defects after rolling ≤ before rolling (i.e., the defects have not worsened and may be improved). If at least one side meets this condition, it means that the rolling has achieved the basic goal of improving defects and is judged as benign rolling; if neither side meets the condition, it means that the rolling process introduces new defects and is judged as malignant rolling.

[0120] Specifically, in step S5, the quality of the temperature difference roller pressing is determined by combining the image comparison results and the colorimetric analysis results.

[0121] Based on the image comparison results indicating benign rolling and the colorimetric analysis results indicating uniform colorimetric properties, the temperature difference rolling is deemed qualified.

[0122] Based on the image comparison results indicating severe rolling pressure and / or the colorimetric analysis results indicating uneven colorimetric properties, the temperature difference rolling pressure is determined to be substandard.

[0123] Specifically, in step S6, the bending distance of the bending machine is determined in response to whether the temperature difference pressure roller is qualified, including:

[0124] If the response and temperature difference pressure roller are qualified, the bending distance of the bending machine is determined to be the default distance; in practice, the default distance is usually 20mm.

[0125] If the response and temperature difference pressure roller are not up to standard, it indicates that the bending distance of the bending machine is less than the default distance; in practice, it is usually 10mm to 15mm.

[0126] Specifically, in step S8, the outer diameter of the molding mandrel is the same as the designed inner diameter of the water intake pipe.

[0127] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0128] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A modular molding method for a high-strength steel water intake pipe for firefighting aircraft, characterized in that, include: Obtain initial surface images of both sides of the 15-5PH steel plate to be processed to determine the corresponding surface defect types and their proportions. The main defect type of the initial surface image on the corresponding side is determined based on the surface defect type and its proportion to determine the temperature difference rolling properties of the surface on the corresponding side. Based on the temperature difference rolling properties of the two sides of the 15-5PH steel plate to be processed, temperature difference rolling is performed on it to obtain rolling surface images of the two sides of the steel plate. Colorimetric analysis was performed on the roll-pressed surface image on the high-temperature side, and the roll-pressed surface image was compared with the initial surface image corresponding to the temperature difference roll pressing. The quality of temperature difference roller pressing is determined by combining image comparison results and colorimetric analysis results. The bending distance of the bending machine is determined in response to whether the temperature difference pressure roller is qualified, so as to bend the steel plate that has been subjected to temperature difference roller pressing so that the steel plate bends to the low temperature side and rolls into a cylindrical shape; Welding is performed at the joints of the cylindrical steel plates, and the welded areas are ground until they are flush with the base material to form the initial steel pipe. A plastic mandrel is placed inside the initial steel pipe to form a plastic steel pipe, and the plastic steel pipe is placed in a furnace for heat treatment to obtain the finished water pipe; The temperature difference roller pressing properties include a high-temperature side and a low-temperature side.

2. The modular molding method for the high-strength steel water intake pipe for firefighting aircraft according to claim 1, characterized in that, The process of determining the corresponding surface defect type based on the initial surface image includes: An initial surface image is acquired using a high-definition camera, and the location of defects in the initial surface image is determined. The defect sub-maps at each defect location are numbered and sent to the machine learning model to determine the defect type of each defect sub-map; Based on the defect type, determine the corresponding surface defect type and the proportion of that surface defect type. The surface defect types include defects that benefit plastic deformation and defects that cause severe plastic deformation; The defect types corresponding to the beneficial defects of plastic deformation include indentations, shallow pits, and rolling stripes; the defect types corresponding to the malignant defects of plastic deformation include microcracks and hairline cracks.

3. The modular molding method for the high-strength steel water intake pipe for firefighting aircraft according to claim 2, characterized in that, The process of determining the main defect type of the corresponding side surface image based on the surface defect type and its proportion includes: The determination of whether to combine the quantity ratio with the surface defect type to determine the main defect type is based on the aforementioned surface defect type. In response to whether the surface defect type is a beneficial defect for plastic deformation or a malignant defect for plastic deformation, the main defect type is determined without considering the proportion of the defects, and the main defect type is determined to be the surface defect type. In response to the surface defect types including beneficial and detrimental plastic deformation defects, the primary defect type is determined by combining the proportion of their quantities. The primary defect type is further determined based on their proportion of quantities. If the proportion of beneficial defects in plastic deformation is greater than the proportion of harmful defects in plastic deformation, then the main defect type is determined to be a beneficial defect in plastic deformation. If the proportion of beneficial defects in plastic deformation is less than the proportion of malignant defects in plastic deformation, then the main defect type is determined to be a malignant defect in plastic deformation. If the proportion of beneficial defects in plastic deformation is equal to the proportion of malignant defects in plastic deformation, then the type of unclaimed defect is determined.

4. The modular molding method for the high-strength steel water intake pipe for firefighting aircraft according to claim 1, characterized in that, The process of determining the temperature difference rolling properties of the two sides based on the main defect types of the two sides includes, Determine the main defect types on both surfaces of the to-be-processed 15-5PH steel plate respectively; Determine the temperature difference rolling attributes of both surfaces according to whether the main defect types are the same, including: If the main defect types are different, determine that the temperature difference rolling attribute of the corresponding surface of the plastic deformation malignant defect is the low-temperature side, and / or determine that the temperature difference rolling attribute of the corresponding surface of the plastic deformation favorable defect is the high-temperature side; If the main defect types are the same, determine the temperature difference rolling attributes of both surfaces according to the main defect type and its quantity proportion, where: If the main defect types are both plastic deformation malignant defects, the temperature difference rolling attribute of the side with a higher quantity proportion is the low-temperature side; If the main defect types are both plastic deformation favorable defects, the temperature difference rolling attribute of the side with a higher quantity proportion is the high-temperature side; If the main defect types are both no-main-defect types, randomly determine the temperature difference rolling attributes of both surfaces.

5. The modular molding method for the high-strength steel water intake pipe for firefighting aircraft according to claim 1, characterized in that, The process of performing chromaticity analysis on the rolling surface image of the high-temperature side includes: Divide the rolling surface image of the high-temperature side into several rolling sub-images and randomly select several pixel points as characteristic pixel points in each rolling sub-image; Determine the chromaticity values of each of the characteristic pixel points respectively to determine its average value, maximum chromaticity value, and minimum chromaticity value; Determine the maximum deviation value according to the maximum chromaticity value and the average value, and determine the minimum deviation value according to the minimum chromaticity value and the average value; Determine the chromaticity fluctuation amount according to the maximum deviation value, the minimum deviation value, and the average value; Determine the chromaticity analysis result according to the magnitude relationship between the chromaticity fluctuation amount and the preset fluctuation amount; Among them, the chromaticity analysis result includes chromaticity uniformity result and chromaticity non-uniformity result.

6. The modular molding method for the high-strength steel water intake pipe for firefighting aircraft according to claim 1, characterized in that, The process of comparing the rolling surface image with the corresponding initial surface image before temperature difference rolling respectively includes: Determine the quantity proportion of plastic deformation favorable defects according to the rolling surface image of each side surface; Compare the quantity proportions of plastic deformation favorable defects in the initial surface image and the rolling surface image of each side surface, and determine the image comparison result according to the comparison result, including: If the comparison result meets the recovery condition, determine that the image comparison result is benign rolling; If the comparison result does not meet the recovery condition, determine that the image comparison result is malignant rolling; Among them, the recovery condition is that the quantity proportion of plastic deformation favorable defects in the rolling surface image is less than or equal to the quantity proportion of plastic deformation favorable defects in the corresponding initial surface image.

7. The modular molding method for the high-strength steel water intake pipe for firefighting aircraft according to claim 1, characterized in that, Combine the image comparison result and the chromaticity analysis result to determine whether the temperature difference rolling is qualified, where, Based on the image comparison result being benign rolling and the chromaticity analysis result being chromaticity uniformity result, determine that the temperature difference rolling is qualified.

8. The modular molding method for the high-strength steel water intake pipe for firefighting aircraft according to claim 1, characterized in that, Respond to whether the temperature difference rolling is qualified to determine the bending distance of the bending machine, including, Respond to the temperature difference rolling being qualified, and determine that the bending distance of the bending machine is the default distance; Respond to the temperature difference rolling being unqualified, and determine that the bending distance of the bending machine is less than the default distance.

9. The modular molding method for the high-strength steel water intake pipe for firefighting aircraft according to claim 1, characterized in that, The outer diameter of the plastic core rod is the same as the designed inner diameter of the water suction pipe.

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