Welding method of stainless steel pipeline for air conditioner

Abstract

The invention relates to the technical field of welding, in particular to a welding method of a stainless steel pipeline for an air conditioner, which comprises the following steps: pretreating a red copper pipe and a stainless steel pipe, flaring two ends of a stainless steel port, and respectively inserting the ports of the red copper pipe into the ports of the two ends of the stainless steel pipe; and sleeving the welding joint with a welding ring, and heating to form a brazed joint. Wherein welding infrared images are collected in real time to determine a temperature change area, so that the temperature difference degree and the change synchronism are determined, and the flowing speed of welding ring welding flux is predicted; welding area images are collected in real time to determine the flowing state of the welding ring, heating power or heating time is adjusted according to the flowing speed, the flowing state, the heat conductivity of the welding ring and pipe parameters, and the position of the welding ring during next welding is adjusted according to the flowing state; welding parameters can be optimized in time according to actual welding conditions, so that the welding ring uniformly flows to fill a welding seam, a smooth and compact brazed joint is formed, and the welding quality is improved.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a welding method for a stainless steel pipeline for an air conditioner. Background Art

[0002] In existing air conditioning pipelines, all copper or copper + aluminum tubes (wrapped with thermoplastic tubes) are often used. However, copper is expensive, which will increase the production cost of air conditioners. In addition, its fast heat dissipation characteristics will affect the gas-liquid separation effect, causing the compressor to inhale liquid refrigerant, reducing the compressor efficiency, and ultimately causing the air conditioner performance coefficient (COP) to be low, affecting the air conditioning cooling and heating efficiency and increasing energy consumption. The copper-aluminum connecting pipe is not environmentally friendly, and due to the different densities of copper and aluminum, a primary battery will be formed in an electrolyte environment, which poses a risk of potential corrosion and increases air conditioning failures.

[0003] Chinese patent publication number: CN107127467A, discloses a welding method for a shock-absorbing pipe for an air conditioner, an air-conditioning pipe system and an air conditioner, the welding method for a shock-absorbing pipe for an air conditioner includes: providing a shock-absorbing pipe; the shock-absorbing pipe includes a pipe body and pipe joints welded and fixed at both ends of the pipe body, the welding temperature of the pipe joint and the pipe body is T1; the end of the pipe joint away from the pipe body is welded and fixed to the air-conditioning pipe; the welding temperature of the pipe joint and the air-conditioning pipe is T2, and T2 and T1 satisfy the relationship: T2<T1. It can be seen that although the above technical solution can realize the welding of the pipe joint and the pipe body and the pipe joint and the air-conditioning pipe, it does not take into account the compatibility of welding different materials, such as the difference in thermal conductivity and melting point of different materials, which will affect heat transfer and welding effect. Summary of the invention

[0004] To this end, the present invention provides a welding method for stainless steel pipes for air conditioners, which is used to overcome the problems in the prior art that when welding air conditioner pipes, the welding material dissipates heat too quickly and has high manufacturing costs, affecting the air conditioner performance, and the material properties of the welding material are not considered during welding to affect the welding quality.

[0005] To achieve the above object, the present invention provides a welding method for stainless steel pipes for air conditioners, comprising: Step S1, pre-treating the copper tube port and the stainless steel tube port to be welded; Step S2, expanding both ends of the stainless steel port, and inserting the copper tube port into the expanded ports at both ends of the stainless steel tube, respectively, to form a welding joint; Step S3, after evenly applying the brazing flux on the surface of the welding joint, putting the welding ring on the welding joint, and heating the welding joint to form a brazed joint; In the heating process, the welding infrared image is collected in real time to determine the temperature change area, the temperature difference degree of the temperature change area is determined according to the area and temperature range of the temperature change area, and the change synchronization is determined according to the number of temperature change areas; Predicting the flow velocity of the solder ring solder according to the degree of temperature difference, the synchronization of the change and the real-time flow velocity of the solder ring solder within a preset time period; Real-time acquisition of welding area images to determine whether the flow state of the welding ring is uniform flow or non-uniform flow; Adjusting the heating power or heating time according to the flow velocity, flow state, thermal conductivity of the welding ring and pipe parameters, and adjusting the welding ring position at the next welding according to the flow state; The pipe material parameters include the thermal conductivity of copper and the thermal conductivity of stainless steel.

[0006] Furthermore, the welding area is divided into temperature change regions based on the temperature distribution of the welding infrared image, and the degree of temperature difference is determined based on the area of ​​the temperature change region and the corresponding temperature range.

[0007] Furthermore, the number of the temperature change regions is determined according to the temperature distribution conditions corresponding to the temperature change regions, and the change synchronization is determined according to a number change curve of the number of the temperature change regions.

[0008] Further, a correlation between the temperature difference degree and the flow velocity is determined according to the temperature difference degree and a preset difference degree threshold, and a flow velocity prediction model is constructed according to the temperature difference degree, the real-time flow velocity, the correlation and the change synchronization to predict the flow velocity of the solder ring; The change synchronization is positively correlated with the flow speed.

[0009] Further, determining the correlation includes: If the temperature difference is less than or equal to the preset difference threshold, the temperature difference is positively correlated with the flow velocity; If the temperature difference is greater than the preset difference threshold, the temperature difference is negatively correlated with the flow velocity.

[0010] Further, determining weld ring contour points according to the weld area image, and determining contour point distances based on the weld ring contour points and initial weld ring contour points to determine flow states; Wherein, a real-time weld ring contour point set is determined according to the weld ring contour points, and an initial weld ring contour point set is determined according to the initial weld ring contour points; Matching the weld ring contour points in the real-time weld ring contour point set with the initial weld ring contour points in the initial weld ring contour point set; The distance between each pair of contour points after matching is calculated to obtain a distance set, and the contour point distance is compared with a distance segmentation threshold, and the flow state is determined according to the comparison result.

[0011] Furthermore, the adjustment method of the heating power or the heating time is determined according to the flow state, and the adjustment of the welding ring position during the next welding is determined, wherein: If the flow state is uniform flow and the flow speed exceeds a preset flow speed range, reducing the heating power or shortening the heating time; If the flow state is uniform flow and the flow speed is lower than a preset flow speed range, increasing the heating power or extending the heating time; If the flow state is uniform flow and the flow speed is within the preset flow speed range, the heating power and the heating time are not adjusted; If the flow state is non-uniform flow, the position of the welding ring in the next welding is adjusted according to the circumferential spacing between the welding ring and the copper tube at several positions in the next welding.

[0012] Furthermore, an adjustment coefficient is determined according to the preset flow velocity range and the flow velocity, and a power adjustment amount of the heating power is determined according to the adjustment coefficient, the thermal conductivity of the welding ring, the thermal conductivity of the copper, the thermal conductivity of the stainless steel and the preset heating power.

[0013] Further, a heat difference corresponding to the speed difference is determined according to the preset flow speed range and the flow speed, and a time adjustment amount of the heating time is determined based on the heat difference and the actual heating power; The flow velocity and heat are positively correlated.

[0014] Furthermore, the spacing consistency is determined according to the circumferential spacing of the plurality of positions so as to adjust the position of the welding ring during the next welding.

[0015] Compared with the prior art, the beneficial effect of the present invention is that the present invention adopts stainless steel and copper to connect to form air-conditioning pipelines, which reduces production costs and saves energy and reduces emissions. At the same time, the present invention collects welding area images and welding infrared images in real time, obtains the degree of temperature difference, temperature change synchronization and welding ring flow state through image analysis, and predicts the flow speed of welding ring solder, and flexibly adjusts the heating power or heating time in combination with factors such as welding ring material and pipe material. By timely optimizing welding parameters according to the actual welding situation, welding defects such as weld nodule accumulation and weld seam filling are avoided, so that the welding ring flows evenly and fully fills the weld seam to form a smooth, dense and perfectly fused brazed joint, thereby further improving the welding quality and stability, enhancing the strength and sealing of the welding part of the stainless steel pipeline for air conditioning, and ensuring the reliable operation of the air conditioning pipeline system.

[0016] Furthermore, the present invention determines the correlation between the temperature difference degree and the flow velocity according to the temperature difference degree and the preset difference degree threshold, so that the model can capture the influence of temperature change on the flow velocity of the solder. Secondly, the temperature difference degree, the real-time flow velocity and the correlation are incorporated into the model construction, and the flow state of the solder in the actual welding and the dynamic change of the flow velocity are fully considered. Furthermore, the introduction of change synchronization enables the model to more comprehensively reflect the real welding phenomenon, thereby more accurately predicting the flow velocity of the solder ring at different stages, providing strong support for the precise control of the welding process, improving the welding quality, and reducing welding defects caused by abnormal solder flow.

[0017] Furthermore, the present invention determines the adjustment method of the heating power or heating time according to the flow state and flow speed, and determines the adjustment of the welding ring position for the next welding, so that after the welding ring reaches a suitable melting state, the heating is stopped in time to avoid excessive flow, or the heating power is increased and the heating time is extended to improve the fluidity of the welding ring. At the same time, the present invention adjusts the welding ring position for the next welding to avoid excessive spacing between local welds, so that the welding ring flows evenly and fully fills the weld, forming a smooth, dense, and perfectly fused brazed joint, thereby improving welding quality and stability.

[0018] Furthermore, the present invention accurately adjusts the position of the welding ring according to the welding seam distance between the welding ring and the copper tube, thereby improving the accuracy and uniformity of the welding ring position, reducing welding defects and quality problems caused by improper welding ring position, thereby improving welding quality and stability, enhancing the strength and sealing of the welding points of stainless steel pipes for air conditioners, and ensuring the reliable operation of the air conditioning pipe system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A half-section view of a stainless steel pipeline for an air conditioner according to an embodiment of the present invention; Figure 2 This is a step diagram of a welding method for a stainless steel pipe for an air conditioner according to an embodiment of the present invention; Figure 3 A step diagram for adjusting heating parameters and welding ring position during welding process according to an embodiment of the present invention; Figure 4 A diagram showing the steps of determining the flow rate of solder in a solder ring according to an embodiment of the present invention; In the figure: 1, stainless steel tube; 2, copper tube; 3, welding ring. DETAILED DESCRIPTION

[0020] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0022] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0023] See also Figure 1 , Figure 2 , Figure 3 As shown, Figure 1 A half-section view of a stainless steel pipeline for an air conditioner according to an embodiment of the present invention; Figure 2 This is a step diagram of a welding method for a stainless steel pipe for an air conditioner according to an embodiment of the present invention; Figure 3 A step diagram for adjusting heating parameters and welding ring position during the welding process according to an embodiment of the present invention.

[0024] Specifically, the present invention provides a welding method for a stainless steel pipe for an air conditioner, comprising: Step S1, pre-treating the copper tube 2 port and the stainless steel tube 1 port to be welded; Step S2, expanding both ends of the stainless steel port, and inserting the ends of the copper tube 2 into the expanded ends of the stainless steel tube 1 to form a welding joint; Step S3, after evenly applying the brazing flux on the surface of the welding joint, putting the welding ring 3 on the welding joint, and heating the welding joint to form a brazed joint; Wherein, during the heating process, step S3 includes: Step S31, real-time acquisition of welding infrared images to determine the temperature change area, determine the degree of temperature difference in the temperature change area according to the area and temperature range of the temperature change area, and determine the change synchronization according to the number of temperature change areas; Step S32, predicting the flow velocity of the solder ring according to the temperature difference degree, the change synchronization and the real-time flow velocity of the solder ring within a preset time period; Step S33, collecting the welding area image in real time to determine whether the flow state of the welding ring 3 is uniform flow or non-uniform flow; Step S34, adjusting the heating power or heating time according to the flow velocity, flow state, thermal conductivity of the welding ring and pipe parameters, and adjusting the position of the welding ring 3 in the next welding according to the flow state; The pipe material parameters include the thermal conductivity of copper and the thermal conductivity of stainless steel.

[0025] It is understandable that before welding, the ends of the copper tube 2 and the stainless steel tube 1 are pretreated to remove impurities. The oxide layer can ensure a good welding foundation. Then the stainless steel tube 1 is expanded and inserted into the copper tube 2 to form a welding joint, which can increase the welding area. The pressure resistance of stainless steel is 3 times higher than that of copper, which can increase the service life. The heat dissipation of stainless steel is 3 times worse than that of copper, and the heat preservation effect is good. It can increase the separation rate of compressed air and improve the cop (energy efficiency ratio) of air conditioners. And stainless steel instead of copper can reduce costs, avoid resource consumption, and achieve energy conservation and emission reduction.

[0026] It is understandable that during the welding process, temperature is a key factor in determining the state of the welding ring. As the temperature rises, the welding ring 3 undergoes a transition from solid to liquid. Different temperature distributions and change trends directly affect the melting speed and fluidity of the welding ring 3. For example, when the temperature distribution in the welding area is uniform and rises slowly, the welding ring 3 can be heated evenly, melt slowly and flow smoothly; on the contrary, if the local temperature is too high, the welding ring 3 will melt quickly in this area, which may cause too fast flow or even splashing; if the temperature is too low, the welding ring 3 will melt slowly, resulting in poor fluidity, which may easily cause insufficient weld filling. By analyzing the temperature distribution, degree of difference and change trend, the melting state and flow trend of the welding ring 3 can be inferred, and then the welding quality can be indirectly determined, so as to achieve timely adjustment of the heating parameters.

[0027] It is understandable that the properties of the welding ring 3 material and the pipe material play an important role in the welding process. Different welding ring 3 materials have different melting points, surface tensions, fluidity, etc. Different pipe materials also have different thermal conductivity and melting points. These parameters will affect the temperature distribution of the welding area. Therefore, adjusting the heating power and time in combination with the material properties can meet the welding requirements of different material combinations and achieve good welding results.

[0028] In a specific embodiment, the value range of the preset time period is 0.5s to 2s, and preferably, the value of the preset time period is 1s. The Vickers hardness of the stainless steel tube 1 is in the range of 130 to 150. The material of the welding ring 3 is brass. In implementation, the value range and preferred value of the preset time period can be determined according to actual conditions, and are not specifically limited here and will not be repeated.

[0029] The present invention adopts stainless steel and copper to form an air conditioning pipeline, which reduces production costs and saves energy and reduces emissions. At the same time, the present invention collects welding area images and welding infrared images in real time, obtains the degree of temperature difference, temperature change synchronization and the flow state of the welding ring 3 through image analysis, and predicts the flow speed of the welding ring solder, and flexibly adjusts the heating power or heating time in combination with factors such as the material of the welding ring 3 and the material of the pipe. By timely optimizing the welding parameters according to the actual welding situation, welding defects such as weld nodule accumulation and weld seam filling are avoided, so that the welding ring 3 flows evenly and fully fills the weld seam to form a smooth, dense and perfectly fused brazed joint, thereby further improving the welding quality and stability, enhancing the strength and sealing of the welding part of the stainless steel pipeline for air conditioning, and ensuring the reliable operation of the air conditioning pipeline system.

[0030] Specifically, the welding area is divided into temperature change areas based on the temperature distribution of the welding infrared image, and the degree of temperature difference is determined based on the area of ​​the temperature change area and the corresponding temperature range.

[0031] It is understandable that during the welding process, since the welding ring 3 is annular, the temperature of different parts is different. The infrared image can reflect the temperature distribution during the welding heating process, and the entire welding area can be divided into different temperature change areas according to the temperature level and change trend to determine the degree of temperature difference. And the larger the area of ​​the temperature change area, it means that during the welding process, a larger range of areas are in this temperature state, which will have a relatively greater impact on the welding quality and affect the welding effect. Therefore, comprehensively considering the area of ​​the temperature change area and the corresponding temperature range can comprehensively evaluate the degree of temperature difference in the welding area, which is convenient for the subsequent evaluation of the flow rate of the welding ring solder.

[0032] In a specific embodiment, an infrared thermal imager can be used to collect welding infrared images. Different colors or gray values ​​in the infrared image correspond to different temperatures. The welding infrared image is processed using an image segmentation algorithm. Based on the similarity between pixels, cluster analysis and other principles, areas with similar temperatures can be divided into a temperature change area. The area of ​​the temperature change area is determined by counting the number of pixels in the temperature change area. The temperature range in the temperature change area can be determined by obtaining the highest temperature and the lowest temperature in the temperature change area. The sum of the weighted temperature values ​​of all temperature change areas = , n is the number of temperature change regions, i=1, 2, .., n. The temperature characterization value of a single temperature change region is the average of the highest temperature and the lowest temperature in the single temperature change region, and the temperature difference degree is: It can be understood that the greater the temperature difference, the higher the temperature difference in the welding area. In practice, the technical means for determining the temperature change area can be selected according to the actual situation, and is not specifically limited here and will not be repeated.

[0033] Specifically, the number of temperature change regions is determined according to the temperature distribution corresponding to the temperature change regions, and the change synchronization is determined according to the number change curve of the temperature change regions.

[0034] It can be understood that if the number of temperature change zones gradually decreases, it means that the temperature of the welding zone tends to be uniform, and if the number of temperature change zones gradually increases, it means that the temperature difference of the welding zone is relatively large, which will affect the solder flow and welding quality of the welding ring 3. Therefore, the synchronization of the temperature change of each temperature change zone can be determined based on the number of temperature change zones.

[0035] In a specific embodiment, the welding infrared images are collected by an infrared thermal imager at different times and then segmented to determine the number of temperature change areas at the corresponding time. The collection time is used as the horizontal coordinate and the corresponding number of temperature change areas is used as the vertical coordinate to construct a quantity change curve, and the slope of the quantity change curve is used as the change synchronization.

[0036] See also Figure 4 As shown, it is a step diagram of determining the flow speed of the solder ring solder according to an embodiment of the present invention; specifically, the correlation between the temperature difference degree and the flow speed is determined according to the temperature difference degree and the preset difference degree threshold, and a flow speed prediction model is constructed according to the temperature difference degree, the real-time flow speed, the correlation and the change synchronization to predict the flow speed of the solder ring solder; The change synchronization is positively correlated with the flow speed.

[0037] It is understandable that under certain conditions, the degree of temperature difference is positively correlated with the flow rate of the welding ring solder, but it is not absolute. Therefore, under the limitation of the size relationship between the preset difference degree threshold and the temperature difference degree, determining the correlation between the temperature difference degree and the flow rate plays a key role in building a flow rate prediction model. And the change synchronization characterizes the consistency of the temperature change over time in each temperature change area. When the change synchronization is good, it means that the temperature of the entire welding area rises or falls evenly, the melting and flow of each part of the welding ring 3 are more uniform and coordinated, and the fluidity is better. On the contrary, if the change synchronization is poor, it will affect the smooth flow of the welding ring solder, thereby causing the flow rate of the welding ring solder to decrease. The real-time flow rate is the result of the combined effect of the temperature difference degree and the change synchronization, which can be used as an important basis when building a prediction model.

[0038] In a specific embodiment, the preset difference degree threshold has a value range of 2 to 3, and preferably, the preset difference degree threshold has a value of 2.5. A mathematical model is established with the temperature difference degree, change synchronization and corresponding time point as input features, the correlation and change synchronization are positively correlated with the flow velocity as constraints, and the real-time flow velocity within a preset time period as the output feature. A flow velocity prediction model is established using a neural network model to determine the temperature difference degree, the real-time flow velocity, and the specific functional relationship between the change synchronization and the flow velocity, and obtain the predicted flow velocity of the solder ring. In implementation, the value range and preferred value of the preset difference degree threshold can be determined according to actual conditions, and are not specifically limited here and will not be repeated.

[0039] The present invention determines the correlation between the temperature difference degree and the flow velocity according to the temperature difference degree and the preset difference degree threshold, so that the model can capture the influence of temperature change on the flow velocity of the solder. Secondly, the temperature difference degree, the real-time flow velocity and the correlation are incorporated into the model construction, and the flow state of the solder in the actual welding and the dynamic change of the flow velocity are fully considered. Furthermore, the introduction of change synchronization enables the model to more comprehensively reflect the real welding phenomenon, thereby more accurately predicting the flow velocity of the solder ring at different stages, providing strong support for the precise control of the welding process, improving the welding quality, and reducing the welding defects caused by abnormal solder flow.

[0040] Specifically, determining the correlation includes: If the temperature difference is less than or equal to the preset difference threshold, the temperature difference is positively correlated with the flow velocity; If the temperature difference is greater than the preset difference threshold, the temperature difference is negatively correlated with the flow velocity.

[0041] It is understandable that when there is a temperature difference, heat will be transferred from the high temperature area to the low temperature area, which will cause the melting degree and speed of the solder ring at different positions to be different. The greater the temperature difference, the greater the temperature difference between the high temperature area and the low temperature area, and the greater the thermal driving force. Under the action of the thermal driving force, the solder will flow from the high temperature area to the low temperature area to achieve thermal equilibrium. Therefore, in this case, the temperature difference is positively correlated with the flow speed.

[0042] It is understandable that if the temperature difference is too large and exceeds the preset difference threshold, the excessive temperature difference will cause the solder ring 3 to overheat in a local area, resulting in changes in the physical properties of the solder ring 3, such as increased viscosity and increased oxidation, etc. These factors will hinder the flow of solder and reduce the flow rate. In addition, if the temperature difference is too large, it may also cause unstable phenomena such as eddy currents and turbulence in the solder flow process, which will also affect the flow rate of the solder. Therefore, in this case, the temperature difference is negatively correlated with the flow rate.

[0043] Specifically, a weld ring contour point is determined according to the weld area image, and a contour point distance is determined based on the weld ring contour point and an initial weld ring contour point to determine a flow state; Wherein, a real-time weld ring contour point set is determined according to the weld ring contour points, and an initial weld ring contour point set is determined according to the initial weld ring contour points; Matching the weld ring contour points in the real-time weld ring contour point set with the initial weld ring contour points in the initial weld ring contour point set; The distance between each pair of contour points after matching is calculated to obtain a distance set, and the contour point distance is compared with a distance segmentation threshold, and the flow state is determined according to the comparison result.

[0044] It can be understood that when the welding ring 3 is not melted, the shape is a regular ring. As the temperature rises, the welding ring 3 begins to melt, the edge of the welding ring 3 becomes blurred, and the shape changes. By extracting the contour information of the welding ring 3 and comparing the contour shapes at different times, it can be determined whether the welding ring 3 begins to melt and the degree of melting.

[0045] In a specific embodiment, the initial weld ring contour can be extracted based on the weld area image taken initially. After the weld area image is grayed and denoised, the image is segmented into the weld area and the background using the OTSU threshold method according to the grayscale difference between the weld area and the background. The segmented image is subjected to edge detection such as edge detection operators Sobel, Canny, etc. to determine the gradient value and direction of each pixel in the weld area image, and then the pixel with a large grayscale change is found as the edge point. Then, a contour extraction algorithm is used, such as a contour tracking algorithm based on a chain code, to extract the complete weld ring contour from the edge points. After the weld ring contour is refined, the redundant points on the contour are removed to obtain a set of weld ring contour points. In implementation, the method for determining the weld ring contour points can be selected according to the actual situation, which is not specifically limited here and will not be repeated.

[0046] In another specific embodiment, for the set of weld ring contour points and the set of initial weld ring contour points at a certain moment, the nearest neighbor matching algorithm is used to match the current contour point with the point closest to the initial contour point, and the corresponding distance set is obtained by calculating the distance of each pair of contour points after matching. The contour point distance of each pair of contour points can be determined by Euclidean distance. The contour point distance determined at the same moment is compared with the distance segmentation threshold, and the flow state is determined according to the comparison result. The distance segmentation threshold is the mean of the contour point distances at the same moment. If the number of contour point distances determined based on the welding area image that is greater than or equal to the distance segmentation threshold is greater than the preset number threshold, the flow state is determined to be uniform flow, otherwise, it is non-uniform flow. The value range of the preset number threshold is 4 / 6 to 5 / 6 of the number of weld ring contour points determined by the corresponding welding area image, and the value of the preset number threshold is 9 / 12 of the number of weld ring contour points determined by the corresponding welding area image. In implementation, the value range and preferred value of the distance segmentation threshold and the preset number threshold can be determined according to actual conditions, and no specific limitation is made here. It is sufficient to ensure that the preset number threshold is determined according to the number of weld ring contour points determined by the welding area image, and no further details are given here.

[0047] Specifically, the adjustment method of the heating power or heating time is determined according to the flow state, and the position adjustment of the welding ring 3 during the next welding is determined, wherein: If the flow state is uniform flow and the flow speed exceeds a preset flow speed range, reducing the heating power or shortening the heating time; If the flow state is uniform flow and the flow speed is lower than a preset flow speed range, increasing the heating power or extending the heating time; If the flow state is uniform flow and the flow speed is within the preset flow speed range, the heating power and the heating time are not adjusted; If the flow state is non-uniform flow, the position of the welding ring 3 in the next welding is adjusted according to the circumferential spacing between the welding ring 3 and the copper tube 2 at several positions in the next welding.

[0048] It is understandable that a suitable flow rate can make the solder evenly fill the gap between the welds of stainless steel and copper. If the flow rate is too fast, the solder will be unevenly distributed in the weld, resulting in local accumulation or unfilled conditions, which will affect the strength and sealing of the welded joint. If the flow rate is too slow, the solder will not be able to fill the weld in time, forming voids or gaps, and reducing the welding quality. When the flow rate of the solder ring is too fast, it may be that the heating power is too high, resulting in the temperature of the solder ring 3 being too high, the viscosity is reduced, and the fluidity is strong. At this time, the heating power should be reduced, the input heat should be reduced, and the flow rate should be slowed down. At the same time, reducing the heating time can also prevent the solder ring 3 from being overheated. For some solder ring 3 materials with strong thermal sensitivity, excessive heating time will increase their fluidity sharply. The flow rate of the solder ring is too slow, which may be due to insufficient heating power, resulting in the failure of the solder ring 3 to melt. Increasing the heating power can increase the heat input and promote the flow of the solder ring. Similarly, extending the heating time can also ensure that the heat is fully transferred to melt the solder ring 3.

[0049] It can be understood that if the flow state is non-uniform, it means that the axes of the welding ring 3 and the welding pipe are not on the same axis at the beginning, which may easily cause the local weld spacing to be too large or the local weld spacing to be too small. Therefore, adjusting the position of the welding ring 3 before welding can improve the welding quality.

[0050] In a specific embodiment, the preset flow velocity range is 2 mm / s to 6 mm / s. Preferably, the preset flow velocity range is 3 mm / s to 5 mm / s. In implementation, the value range of the preset flow velocity range can be determined according to the specific material of the welding ring 3. No specific limitation is made here and no further details are given.

[0051] The present invention determines the adjustment method of the heating power or heating time according to the flow state and flow speed, and determines the adjustment of the position of the welding ring 3 at the next welding, so that after the welding ring 3 reaches a suitable melting state, the heating is stopped in time to avoid excessive flow, or the heating power is increased and the heating time is extended to improve the fluidity of the welding ring 3. At the same time, the present invention adjusts the position of the welding ring 3 at the next welding to avoid excessive spacing of local welds, so that the welding material of the welding ring 3 flows evenly and fully fills the weld, forming a smooth, dense, and perfectly fused brazed joint, thereby improving welding quality and stability.

[0052] Specifically, an adjustment coefficient is determined according to the preset flow velocity range and the flow velocity, and a power adjustment amount of the heating power is determined according to the adjustment coefficient, the thermal conductivity of the welding ring, the thermal conductivity of copper, the thermal conductivity of stainless steel and the preset heating power.

[0053] In a specific embodiment, the preset flow velocity characterization value is the average of the highest flow velocity and the lowest flow velocity in the preset flow velocity range, and the adjustment coefficient is The power adjustment amount of the heating power = adjustment coefficient × preset heating power × , the average of the thermal conductivity of copper and the thermal conductivity of stainless steel is the average of the thermal conductivity, the value range of the preset heating power is 500W to 800W, preferably, the value of the preset heating power is 600W to 700W. In implementation, the value range and preferred value of the preset heating power and the adjustment coefficient can be determined according to actual conditions, and are not specifically limited here and will not be repeated.

[0054] Specifically, a heat difference corresponding to the speed difference is determined according to the preset flow speed range and the flow speed, and a time adjustment amount of the heating time is determined based on the heat difference and the actual heating power; Wherein, the flow velocity and heat are positively correlated; It can be understood that if the flow state is uniform but the speed is slow, it means that the overall heat is insufficient and the heating time needs to be extended. Conversely, if the flow speed is fast, it means that there is too much heat and the heating time can be appropriately shortened.

[0055] In a specific embodiment, the time adjustment amount of the heating time is the ratio of the heat gap to the actual heating power. Based on the heat conduction formula, the heat range corresponding to the preset flow velocity range can be obtained. According to the flow velocity and the heat conduction formula, the actual heat corresponding to the flow velocity can be determined. The heat gap is the difference between the heat range mean and the actual heat range.

[0056] Specifically, the spacing consistency is determined according to the circumferential spacing of the plurality of positions so as to adjust the position of the welding ring 3 during the next welding.

[0057] It is understandable that by adjusting the position of the welding ring 3, the distribution of the welding ring 3 in the circumferential direction can be made more uniform and reasonable, which helps to achieve uniform welding and reduce welding defects caused by position deviation of the welding ring 3. If the position of the welding ring 3 deviates and is not on the same axis as the position of the welded pipe, it is easy to affect the welding quality and cause defects such as welds.

[0058] In a specific embodiment, a high-precision measuring instrument, such as a laser rangefinder or an optical measuring device, is used to accurately measure the gap distance between the copper tube 2 and the welding ring 3 corresponding to several positions, that is, the circumferential spacing. The spacing consistency is determined by determining the average value between the several circumferential spacings. If the number of circumferential spacings that exceeds the average value is greater than 1 / 2 of the total number of circumferential spacings, the position of the welding ring 3 is adjusted during the next welding, and the adjustment direction is determined according to the circumferential spacing to reduce the spacing deviation and make the circumferential spacing as uniform as possible.

[0059] The present invention accurately adjusts the position of the welding ring 3 according to the welding seam distance between the welding ring 3 and the copper tube 2, thereby improving the accuracy and uniformity of the position of the welding ring 3, reducing welding defects and quality problems caused by improper position of the welding ring 3, thereby improving welding quality and stability, enhancing the strength and sealing of the welding point of the stainless steel pipeline for air conditioning, and ensuring the reliable operation of the air conditioning pipeline system.

[0060] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle 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 fall within the protection scope of the present invention.

Claims

1. A welding method for stainless steel pipes for air conditioners, characterized in that: include: Step S1, pre-treating the copper tube port and the stainless steel tube port to be welded; Step S2, expanding both ends of the stainless steel port, and inserting the copper tube port into the expanded ports at both ends of the stainless steel tube, respectively, to form a welding joint; Step S3, after evenly applying the brazing flux on the surface of the welding joint, putting the welding ring on the welding joint, and heating the welding joint to form a brazed joint; In the heating process, the welding infrared image is collected in real time to determine the temperature change area, the temperature difference degree of the temperature change area is determined according to the area and temperature range of the temperature change area, and the change synchronization is determined according to the number of temperature change areas; Predicting the flow velocity of the solder ring solder according to the degree of temperature difference, the synchronization of the change and the real-time flow velocity of the solder ring solder within a preset time period; Real-time acquisition of welding area images to determine whether the flow state of the welding ring is uniform flow or non-uniform flow; Adjusting the heating power or heating time according to the flow velocity, flow state, thermal conductivity of the welding ring and pipe parameters, and determining the welding ring position before the next welding according to the flow state; The pipe material parameters include the thermal conductivity of copper and the thermal conductivity of stainless steel.

2. The welding method for stainless steel pipes for air conditioners according to claim 1, characterized in that: The welding area is divided into temperature change areas based on the temperature distribution of the welding infrared image, and the degree of temperature difference is determined based on the area of ​​the temperature change area and the corresponding temperature range.

3. The welding method for stainless steel pipes for air conditioners according to claim 2, characterized in that: The number of temperature change regions is determined according to the temperature distribution corresponding to the temperature change regions, and the change synchronization is determined according to the number change curve of the number of temperature change regions.

4. The welding method for stainless steel pipes for air conditioners according to claim 3, characterized in that: Determine the correlation between the temperature difference degree and the flow velocity according to the temperature difference degree and the preset difference degree threshold, and construct a flow velocity prediction model according to the temperature difference degree, the real-time flow velocity, the correlation and the change synchronization to predict the flow velocity of the solder ring; The change synchronization is positively correlated with the flow speed.

5. The welding method for stainless steel pipes for air conditioners according to claim 4, characterized in that: Determining the correlation includes: If the temperature difference is less than or equal to the preset difference threshold, the temperature difference is positively correlated with the flow velocity; If the temperature difference is greater than the preset difference threshold, the temperature difference is negatively correlated with the flow velocity.

6. The welding method for stainless steel pipes for air conditioners according to claim 1, characterized in that: Determine a weld ring contour point according to the weld area image, and determine a contour point distance based on the weld ring contour point and an initial weld ring contour point to determine a flow state; Wherein, a real-time weld ring contour point set is determined according to the weld ring contour points, and an initial weld ring contour point set is determined according to the initial weld ring contour points; Matching the weld ring contour points in the real-time weld ring contour point set with the initial weld ring contour points in the initial weld ring contour point set; The distance between each pair of contour points after matching is calculated to obtain a distance set, and the contour point distance is compared with a distance segmentation threshold, and the flow state is determined according to the comparison result.

7. The welding method for stainless steel pipes for air conditioners according to claim 6, characterized in that: Determine the adjustment method of heating power or heating time according to the flow state, and adjust the welding ring position before the next welding, including: If the flow state is uniform flow and the flow speed exceeds a preset flow speed range, reducing the heating power or shortening the heating time; If the flow state is uniform flow and the flow speed is lower than a preset flow speed range, increasing the heating power or extending the heating time; If the flow state is uniform flow and the flow speed is within the preset flow speed range, the heating power and the heating time are not adjusted; If the flow state is non-uniform flow, the position of the welding ring before the next welding is determined according to the circumferential spacing between the welding ring and the copper tube at several positions during the next welding.

8. The welding method for stainless steel pipes for air conditioners according to claim 7, characterized in that: An adjustment coefficient is determined according to the preset flow velocity range and the flow velocity, and a power adjustment amount of the heating power is determined according to the adjustment coefficient, the thermal conductivity of the welding ring, the thermal conductivity of the copper, the thermal conductivity of the stainless steel and the preset heating power.

9. The welding method for stainless steel pipes for air conditioners according to claim 8, characterized in that: Determine a heat difference corresponding to the speed difference according to the preset flow speed range and the flow speed, and determine a time adjustment amount of the heating time based on the heat difference and the actual heating power; The flow velocity and heat are positively correlated.

10. The welding method for stainless steel pipes for air conditioners according to claim 7, characterized in that: The spacing consistency is determined based on the circumferential spacing at a plurality of positions so as to adjust the welding ring position during the next welding.

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