Copper casting defect repair welding treatment method based on dye penetrant inspection technology

Abstract

The invention relates to the technical field of metal casting and nondestructive testing, and discloses a copper casting defect repair welding treatment method based on a dye penetrant inspection technology, which comprises the following steps: collecting the maximum depth and the surface opening width of a defect to be repaired by welding as geometric parameters; initial repair welding is carried out, and when abnormal interruption is monitored, an interruption area to be processed is determined; an auxiliary heating device is started to heat the area to the target temperature, and the purification temperature holding time is calculated according to the geometric parameters; maintaining the target temperature until the purification holding time is reached, driving the residual flaw detection agent to be gasified and discharged by utilizing thermal power, and then covering and preserving heat by utilizing a heat preservation material; and when the rework condition is met, the welding seam heat state is adjusted to be within the interlayer temperature range, and continuous welding is conducted. According to the method, through active purification and standardized temperature control based on defect morphology, the air hole hidden danger caused by deep penetrating agent residues is effectively eliminated, cracks generated by quenching of the copper casting are prevented, and the welding repair quality is improved.

Description

Technical Field

[0001] This invention relates to the fields of metal casting and nondestructive testing technology, and in particular to a method for repairing defects in copper castings by welding based on dye penetrant testing technology. Background Technology

[0002] In the metal casting industry, surface defects such as cracks and porosity are inevitable in castings. To ensure product quality, these defects must be detected and repaired. Currently, surface defect detection in castings typically employs methods such as radiographic testing and ultrasonic testing. While these methods offer high accuracy, they are expensive, involve complex procedures, and are not readily apparent for detecting small, open surface defects. In contrast, dye penetrant testing (DPT) is widely used in industrial quality inspection due to its low cost, ease of operation, and intuitive visualization of open surface defects. After defects are detected, they are usually filled and repaired using processes such as arc welding or gas welding.

[0003] However, existing dye penetrant testing and subsequent welding repair processes are often disconnected, lacking effective data linkage and process guidance. In particular, when welding repair operations are unexpectedly interrupted, the existing handling methods have obvious technical defects.

[0004] First, dye penetrants penetrate deep into defects via capillary action. For deep and narrow cracks, ordinary surface cleaning is insufficient to completely remove penetrant residues at the bottom. Existing welding repair processes often neglect to utilize the interruption gap to treat deep residues when interrupted. This leads to the rapid vaporization of residual organic solvents under the high-temperature arc during subsequent rework, easily forming porosity defects inside the weld.

[0005] Secondly, copper and copper alloys have high thermal conductivity and coefficient of linear expansion. If an abnormal interruption occurs during the welding process (such as a power outage or equipment failure), and there is a lack of targeted thermal insulation measures, the high-temperature welded area will rapidly dissipate heat to the surrounding substrate, resulting in a sharp cooling. Existing methods typically do not specify a clear interruption insulation mechanism, leading to significant shrinkage stress in the welded area due to sudden cooling, which can induce thermal cracks or secondary cracking.

[0006] Finally, when resuming work after an interruption, existing technology lacks a standardized matching logic for the thermal state of the weld, and operators often rely on experience to directly start the arc and continue welding. If welding continues when the weld temperature is too low, it is easy to cause incomplete fusion between layers; if welding continues when the temperature is too high, it will lead to coarse grains, which will seriously affect the mechanical properties of the joint. Summary of the Invention

[0007] The purpose of this invention is to provide a method for repairing defects in copper castings based on dye penetrant testing technology. This method solves the problem of lacking a linkage mechanism that combines the defect characteristics of dye penetrant testing with the interruption process of welding repair, which is unable to effectively solve the problems of porosity caused by deep penetrant residue, cracks caused by interrupted cooling, and unstable joint quality caused by temperature mismatch during rework.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for repairing weld defects in copper castings based on dye penetrant testing technology includes the following steps:

[0010] The first step is to collect and define the geometric parameters of the defects. Operators use 3D scanning equipment to collect data on the defects to be repaired on the surface of the copper casting, identified after imaging with a dye penetrant. The maximum depth and surface opening width of the defect are measured and defined as geometric parameters. This step achieves the digital quantification of defect characteristics, providing precise input variables for subsequent interruption processing.

[0011] The second step involves initial welding repair and interruption triggering. An arc welding torch is used to fill the defect with multiple layers and passes. When a welding operation is detected to have stopped, this state is defined as an abnormal interruption, and the resulting area containing unfused weld seams and the heat-affected zone is identified as the interruption area to be addressed.

[0012] The third step involves implementing interrupted purification and heat preservation based on geometric parameters. Operators activate the auxiliary heating device to heat the interrupted area and maintain it at the target temperature. At this point, the previously collected geometric parameters are retrieved, and the purification holding time is calculated using the purification holding time formula.

[0013] Keep the auxiliary heating device on to maintain the interrupted area to be treated at the target temperature until the calculated purification holding time is reached.

[0014] During this period, continuous heat input drives the penetrant residue deep inside the defect to overcome capillary forces and vaporize and be discharged.

[0015] After the purification holding time is reached, the auxiliary heating device is removed and the interrupted area to be treated is tightly covered with insulation material, so that the interrupted area cools down at a controlled rate without any residue.

[0016] The fourth step is to perform weld repair and thermal condition matching. Once the conditions for repair are met, remove the insulation material and measure the instantaneous temperature of the weld surface using a contact thermometer or infrared thermometer. Compare the instantaneous temperature with the minimum and maximum interpass temperatures, and adjust the weld's thermal condition based on the comparison results. After meeting the required temperature conditions, start the arc welding torch to continue welding, thereby obtaining the repaired copper casting.

[0017] In the above technical solution, to achieve precise removal of penetrant residue, the purification holding time formula establishes a quantitative relationship between time parameters and spatial geometric parameters. The specific calculation logic is as follows:

[0018] The purification holding time is equal to the product of the penetrant evaporation resistance coefficient, the maximum depth, and the correction factor; where the correction factor is equal to the value plus the ratio of the maximum depth to the surface opening width.

[0019] The calculation logic indicates that for defects with greater depth or larger aspect ratio, the system will automatically extend the heating holding time to match the physical process required for residues to escape from the bottom.

[0020] Furthermore, the target temperature range is set to 300 to 350 degrees Celsius. This temperature range is based on the following:

[0021] On the one hand, this temperature is higher than the physical boiling point of the organic solvent in conventional dyeing agents, providing the necessary vaporization energy;

[0022] On the other hand, this temperature is within the stress-relief annealing temperature range of copper castings, which helps to alleviate the thermal stress caused by sudden interruption of welding.

[0023] To ensure welding quality after resumption of work, this invention sets a strict thermal state adjustment logic: if the instantaneous temperature is less than the minimum interpass temperature, the auxiliary heating device is activated to reheat the weld until the temperature rises to between the minimum and maximum interpass temperatures; if the instantaneous temperature is greater than the maximum interpass temperature, the work is suspended and natural air cooling is performed until the temperature drops to the specified range; if the instantaneous temperature is between the two thresholds, it is determined that the requirements are met, the current state is maintained, and welding is continued.

[0024] Furthermore, the present invention also assists in the execution of interruption processing steps by using a welding repair auxiliary system equipped with a central processing unit and a heating control terminal.

[0025] After receiving an abnormal interruption signal, the central processing unit automatically extracts geometric parameters and calculates the purification holding time based on the aforementioned logic. This time is then displayed to the operator in the form of a countdown via the heating control terminal. This guides the operator to accurately determine the timing for removing the auxiliary heating device and covering the interrupted area with insulation material, thus achieving standardized closed-loop control from data acquisition to emergency response.

[0026] In summary, the present invention has at least one of the following beneficial technical effects:

[0027] 1. This invention constructs a quantitative correlation between defect geometric features and weld repair interruption processing by collecting the maximum depth and surface opening width of defects and calculating the heat treatment time using the purification holding time formula. This active purification mechanism based on geometric parameters ensures that the dye penetrant residue deep at the bottom of narrow and deep defects can obtain sufficient heat energy to completely vaporize and be discharged, effectively solving the problem of porosity defects in the weld seam caused by the failure to remove residues in the traditional process.

[0028] 2. This invention employs a composite treatment strategy during abnormal interruptions, first using constant-temperature heating for purification and then covering with insulation material. The target temperature is set between 300 and 350 degrees Celsius. This temperature range satisfies the thermodynamic conditions for the evaporation of organic solvents and utilizes the stress-relief annealing characteristics of copper alloys. This prevents hot cracks in copper castings caused by rapid cooling due to their high thermal conductivity, while eliminating residual welding stress and ensuring the structural stability of the interrupted area to be treated.

[0029] 3. This invention establishes a matching logic for the thermal state of resumption of work based on the comparison of instantaneous temperature and interlayer temperature thresholds, and combines it with the automated command control of the welding repair auxiliary system to achieve a standardized connection from interruption to resumption of work. This mechanism avoids problems such as incomplete fusion caused by excessively low resumption temperature or coarse grains caused by excessively high temperature, reduces reliance on the personal experience of operators, and ensures the success rate of welding repair of copper castings and the consistency of joint quality under sudden working conditions. Attached Figure Description

[0030] Figure 1 This is a flowchart of a method for repairing defects in copper castings based on dye penetrant testing technology according to the present invention.

[0031] Figure 2 This is a flowchart of the defect geometry parameter acquisition process of the present invention;

[0032] Figure 3 This is a flowchart of the interrupted purification and heat preservation process based on geometric parameters according to the present invention. Detailed Implementation

[0033] The following is in conjunction with the appendix Figure 1 - Appendix Figure 3The present invention will be further described in detail below.

[0034] Please refer to the appendix. Figure 1 This invention provides a method for repairing weld defects in copper castings based on dye penetrant testing technology. This method is widely applicable to quality control in the metal casting industry and mainly includes the following steps:

[0035] Step S1: Acquisition and definition of defect geometric parameters. The operator applies a dye penetrant to the surface of the pre-treated copper casting and determines the geometric parameters based on the imaging results. The location of the defect to be welded. The operator uses a depth gauge or 3D scanning equipment to target the identified defect. Data was collected from each defect to be welded, measuring its maximum depth and surface opening width.

[0036] The maximum depth obtained by measurement is defined as The measured surface opening width is defined as The above. and These are collectively referred to as geometric parameters. The operator enters these geometric parameters into the database module as the input basis for calculating the purification holding time in the subsequent step S3.

[0037] Step S2: Initial Welding Repair and Interruption Trigger. The welder or welding robot uses an arc welding torch to perform multi-layer, multi-pass filling of the defect locations measured in Step S1, according to the copper alloy welding process specifications. If the welding operation stops due to environmental factors or equipment failure during the repair process, this state is defined as an abnormal interruption. At this time, an interruption area containing unfused weld seams and a heat-affected zone is created, and this area becomes the processing target for Step S3.

[0038] Step S3: Interruption purification and heat preservation based on geometric parameters. After an abnormal interruption occurs, the operator activates the auxiliary heating device to heat the interrupted area to be treated. The target heating temperature is controlled between 300°C and 350°C. This temperature range brings the interrupted area to a thermodynamic state conducive to the vaporization of organic residues.

[0039] Using the geometric parameters recorded in step S1 and combining them with preset process constants, the purification holding time formula is used to calculate the duration for which the target temperature must be maintained in the area before covering and insulating. This duration is defined as the purification holding time. The purification holding time formula is as follows:

[0040] ;

[0041] In the formula: Indicates the purification and temperature holding time; Indicates the resistance coefficient to penetrant evaporation; Indicates the first The maximum depth of the defect to be welded; Indicates the first The width of the opening on the surface to be welded to repair the defect.

[0042] Keep the auxiliary heating device on to maintain the target temperature of the interrupted area within the set range until the calculated purification holding time is reached. This process uses thermodynamics to drive the vaporization and discharge of residual flaw detector material deep within the area. Once the heating time reaches the purification holding time, the operator removes the auxiliary heating device and covers the interrupted area with asbestos cloth or other insulation material to create an intermediate state with no flaw detector residue and a controlled cooling rate, awaiting conditions for resuming work.

[0043] Step S4: Weld Repair Rework and Thermal Condition Matching. When rework conditions are met, the operator removes the asbestos cloth or other insulation material applied in Step S3. The operator uses a contact thermometer or infrared thermometer to measure the instantaneous temperature of the weld surface. The minimum and maximum interpass temperatures specified in the welding process are used as benchmarks.

[0044] If the instantaneous temperature is lower than the minimum interpass temperature, the auxiliary heating device is activated to reheat to the specified range; if the instantaneous temperature is greater than or equal to the minimum interpass temperature but less than or equal to the maximum interpass temperature, the current state is maintained; if the instantaneous temperature is greater than the maximum interpass temperature, natural air cooling is performed. Once the temperature meets the requirements, the welder restarts the arc welding torch and continues welding according to the original process path to obtain a repaired casting with no internal porosity and good interpass fusion.

[0045] See attached document Figure 2 Before performing the welding repair process, the process of collecting geometric parameters of defects on the surface of the copper casting in step S1 includes the following specific steps:

[0046] Step S101: Surface pretreatment of copper castings. Operators clean the area of ​​the copper casting to be inspected, removing oil, rust, scale, and welding spatter. The specific cleaning method is selected based on the surface roughness and contamination level of the copper casting, using organic solvent cleaning, stainless steel wire brush polishing, or sandblasting.

[0047] The cleaning process covers the area to be welded and its surrounding area, ensuring the surface is dry and free of contaminants that could hinder the penetration of the penetrant. For specific process parameters and operating procedures for surface pretreatment, those skilled in the art can refer to relevant national or industry standards for nondestructive testing; these will not be elaborated upon here.

[0048] Step S102, Defect Imaging and Location. The operator applies a dye penetrant evenly to the surface of the pretreated copper casting. The dye penetrant includes a penetrant, a cleaning agent, and a developer. After the penetrant remains wetted and penetrates the surface opening defect within a specified time, excess penetrant is removed from the surface and the developer is applied.

[0049] The penetrant adsorbed at the defect due to capillary action re-permeates under the action of the developer, appearing as a clear red or dark mark on a white background. Based on the development results, the operator visually identifies and marks the locations of all defects on the surface of the copper casting, determining the first... The specific coordinates or relative position of the defect to be welded.

[0050] Step S103, Data Acquisition and Parameter Measurement. For the determined... For each defect to be welded and repaired, the operator uses a depth gauge or 3D scanning equipment to quantitatively measure its geometric dimensions.

[0051] In one embodiment, a depth gauge is used as the measuring tool. The operator inserts the probe of the depth gauge vertically into the first... At the opening of the defect to be welded, the probe tip contacts the bottom of the defect and reads the measurement value as the maximum depth; the measuring jaws of the caliper or depth gauge are used to measure the lateral span of the opening of the defect on the surface of the copper casting, and the measurement value is read as the surface opening width.

[0052] In another embodiment, a 3D scanning device is used as the measuring tool. An operator holds or operates the 3D scanner via a robotic arm to measure the... The system performs optical scanning on the defect to be repaired and its surrounding area to acquire high-precision point cloud data containing the internal surface morphology of the defect. The built-in measurement software automatically identifies the defect edge and the lowest point at the bottom based on the point cloud data, and calculates the maximum vertical distance on the normal section of the defect and the maximum spacing of the surface opening contours.

[0053] Step S104: Definition and Input of Geometric Parameters. Based on the measurement results of step S103, clearly define the geometric parameters. Geometric parameters of a defect to be welded.

[0054] The vertical distance from the deepest point of the defect to the reference surface of the copper casting is defined as the maximum depth, denoted as . The unit is millimeters; the maximum opening distance of the defect on the surface of the copper casting is defined as the surface opening width, denoted as . The unit is millimeters.

[0055] The operator will do the above and Enter data into the database module. The database module creates defect numbers. The mapping relationship between the database and its corresponding geometric parameters and position information provides a direct data source for calculating the purification holding time in the subsequent step S3. This database module is located on a local server or cloud storage medium and is connected to the central processing unit in the subsequent process through a communication interface.

[0056] After acquiring the defect geometry parameters, the process proceeds to step S2, the initial welding repair implementation and interruption triggering stage, which includes the following steps:

[0057] Step S201: Initial Welding Repair Implementation. Based on the location of the defect to be repaired determined in Step S1, the welder or welding robot selects an arc welding torch that matches the material of the copper casting as the heat source to perform the welding repair operation. The arc welding torch includes a tungsten inert gas (TIG) welding torch or a metal inert gas (MIG) welding torch.

[0058] During the welding repair process, the copper alloy welding process specifications are followed, and the defective areas are filled with multiple layers and passes. Given the high thermal conductivity of copper and copper alloys, and their susceptibility to incomplete fusion and porosity, the preheating temperature control, welding current selection, and shielding gas flow rate settings outlined in the welding process specifications can be found in relevant welding manuals for those skilled in the art, based on the material grade and plate thickness; therefore, they will not be elaborated upon here.

[0059] Step S202: Definition and Monitoring of Abnormal Interruptions. During the multi-layer, multi-pass welding process, the status of the welding operation is monitored in real time. When the welding operation stops before defects are fully repaired and the normal process completion point is reached, this state is defined as an abnormal interruption.

[0060] Unnatural interruptions can be triggered by environmental factors, equipment malfunctions, or human factors.

[0061] Environmental factors include sudden power outages or failure of on-site lighting;

[0062] Equipment malfunctions include overheating protection of the welding machine power supply, jamming of the wire feeding mechanism, or failure of the cooling circulation system;

[0063] Human factors include welders being forced to leave their work positions due to sudden health conditions or emergency reassignment.

[0064] Step S203: Formation of the interrupted area to be processed. Once an abnormal interruption is triggered, the welding repair operation stops immediately, at which point an intermediate state area is formed on the copper casting.

[0065] The intermediate zone includes a filled but not yet completed unfused weld, and a heat-affected zone of the base material surrounding the weld that is affected by the welding thermal cycle.

[0066] The area containing the unfused weld and heat-affected zone is defined as the interruption area to be treated. This interruption area has a high temperature gradient, and due to the sudden stop of the welding process, the molten pool solidifies rapidly. Without intervention, it is highly susceptible to hot cracking due to the high coefficient of linear expansion of copper. This interruption area serves as the direct physical object for the subsequent purification and heat preservation operations in step S3.

[0067] See attached document Figure 3 After the interrupted area to be processed is generated in step S2, in order to prevent the copper casting from cracking due to rapid cooling and to use the interruption gap to eliminate the residual testing agent in the deep defects, the following specific steps need to be performed in step S3:

[0068] Step S301: Establish a clean temperature field. After an abnormal interruption occurs, the operator immediately activates the auxiliary heating device to heat the area to be treated. The auxiliary heating device is a flame heater or induction heater capable of providing stable heat input. The operator adjusts the power of the auxiliary heating device to raise and maintain the temperature of the area to be treated at the set target temperature.

[0069] The target temperature is denoted as Considering the stress-relief annealing characteristics of copper alloys and the physical boiling points of organic solvents in conventional dye penetrant testing agents, the target temperature is controlled between 300℃ and 350℃, which satisfies the relationship... Within this temperature range, the copper substrate is in a stress-relief annealing state, which can alleviate the thermal stress caused by welding interruption;

[0070] At the same time, this temperature is higher than the boiling point of the organic permeating agent, providing the necessary thermodynamic conditions for the phase change vaporization of the residue.

[0071] Step S302: Calculate the purification holding time. While maintaining heating, determine the duration for which the target temperature needs to be maintained. This duration is not a fixed value, but is dynamically calculated based on the geometric characteristics of the defect.

[0072] The operator or control system retrieves the geometric parameters recorded in step S1, i.e., the maximum depth, stored in the database module. and surface opening width The purification holding time is calculated using the pre-set process constants and the purification holding time formula. The purification holding time formula is as follows:

[0073] ;

[0074] In the formula: This indicates the purification holding time, which is the duration for which the target temperature needs to be maintained before covering with insulation material; The penetrant volatilization resistance coefficient represents the ease with which the penetrant volatilizes in the pores of a specific copper matrix. It is a preset constant. The relationship between the time required for the residue to completely evaporate at the target temperature and the defect depth can be determined through a preliminary experiment. This involves creating a standard artificial defect on a test block of the same material, applying the same type of penetrant, and then measuring the relationship between the defect depth and the experimental results. Indicates the first The maximum depth of the defect to be welded; Indicates the first The width of the opening on the surface to be welded to repair the defect.

[0075] This formula reflects the kinetic mechanism of the thermal purification process: the maximum depth of the defect. The larger the defect, the longer the path for the residue to diffuse from the bottom to the surface, and the longer the heating time required; the aspect ratio of the defect... The larger the crack, the deeper and narrower it is, and the greater the flow resistance of the gas, requiring a further extension of the heating time to ensure complete purification.

[0076] Step S303: Perform active purification and passive heat preservation. The operator keeps the auxiliary heating device on to maintain the temperature of the interrupted area to be treated within the set range of the target temperature until the heating time reaches the purification holding time calculated in step S302. During this process, the dye penetrant residue deep inside the defect is heated and vaporized, and discharged to the surface of the casting by overcoming capillary forces.

[0077] Once the heating time reaches the purification holding time, the operator should immediately turn off and remove the auxiliary heating device, and quickly cover the area to be treated with asbestos cloth or other insulation materials.

[0078] The asbestos cloth or other insulation materials used have the characteristics of high temperature resistance and low thermal conductivity, which can reduce the cooling rate of the interrupted area to be treated and prevent the temperature from dropping suddenly due to the high thermal conductivity of copper.

[0079] At this point, the area to be processed enters an intermediate state where there is no residual flaw detector and the cooling rate is controlled, until the conditions for resuming work are met. The conditions for resuming work include power restoration, completion of equipment repair, or personnel arrival.

[0080] After the interrupted area has undergone sufficient cleaning and insulation, once the conditions for resuming work are met, the process proceeds to step S4, the welding repair and restoration stage. This stage aims to smoothly transition the interrupted state back to the normal welding process state, and the specific steps are as follows:

[0081] Step S401: Removal of Insulation Cover and Environmental Verification. Once the conditions for resuming work are met, such as power restoration, equipment troubleshooting, or personnel availability, the operator removes the asbestos cloth or other insulation material applied to the surface of the interrupted area in step S3. The operator then checks the surface of the weld repair area for any asbestos fiber residue or other foreign matter introduced by the insulation, and performs simple surface cleaning using a wire brush or compressed air to ensure the cleanliness of the welding surface.

[0082] Step S402: Thermal Condition Monitoring and Temperature Matching. To ensure a good metallurgical bond between the continued weld and the original weld and base material, the current temperature condition must be strictly controlled. Operators use a contact thermometer or infrared thermometer to measure the real-time temperature of the weld surface. The weld surface temperature measured at this time is defined as the instantaneous temperature, denoted as . The unit is Celsius.

[0083] Simultaneously, based on the Welding Procedure Qualification Document (WPS) for copper alloys, the permissible interpass temperature range during welding of this material is determined. The lower limit of the interpass temperature required by the welding procedure specification is defined as the minimum interpass temperature, denoted as . The unit is degrees Celsius; the upper limit of the interpass temperature required by the welding process specification is defined as the maximum interpass temperature, denoted as . The unit is Celsius.

[0084] Operators or the temperature control system will set the instantaneous temperature. With the specified process window Perform a comparison and execute the corresponding heat matching action based on the comparison results:

[0085] like This indicates that the weld temperature is too low at this point, and direct welding may lead to incomplete fusion or cold cracking. The operator restarted the auxiliary heating device to evenly reheat the weld area until the temperature rose back to normal. Within the range.

[0086] like This indicates that the weld seam is experiencing excessive heat accumulation, and direct welding may lead to coarse grains or hot cracking. The operator should suspend work and allow the weld area to air-cool naturally until the temperature drops to a suitable level. Within the range.

[0087] like This indicates that the current thermal condition is suitable; maintain the current condition and prepare for continued welding immediately.

[0088] Step S403: Continued Welding and Repair Completed. When the temperature of the weld area is confirmed to be within the aforementioned process window, the welder restarts the arc welding torch. The arc starting point is selected behind the original interrupted weld pool, overlapping by a certain distance to ensure penetration at the joint.

[0089] The welder continues the remaining welding repair work according to the original welding path until the crack is completely sealed or the defect is filled. Because the previous step S3 used the interruption gap for high-temperature purification based on geometric parameters, the weld interface at this point is in a clean state without any organic penetrant residue, effectively avoiding the generation of porosity in the weld section.

[0090] To ensure the standardized execution of the aforementioned welding repair and interruption purification processes, and to address the issue of insufficient precision in temperature and time control during manual operation, this invention also provides a welding repair auxiliary system. This welding repair auxiliary system mainly consists of a detection and welding repair workstation, a welding repair information database, a central processing unit, and a welding repair operation guidance terminal.

[0091] The inspection and welding repair workstation is equipped with a high-precision 3D scanner and a welding repair robot (or a manual welding station equipped with sensors). The 3D scanner, as the front-end device for data acquisition, is responsible for performing the data acquisition action in step S1.

[0092] After development with dye penetrant, a 3D scanner scans the surface of the copper casting to acquire the 3D morphological data of the defects. The system's built-in image processing algorithm automatically identifies the boundary and bottom features of the defects, extracts two key geometric parameters—maximum depth and surface opening width—and correlates them with the spatial coordinates of the defects on the casting.

[0093] The weld repair information database is used to achieve data sharing between inspection data and the weld repair process. This database stores the material type, thickness information, and geometric parameters of each defect uploaded by the 3D scanner for the copper casting.

[0094] In addition, the database also pre-stores process constants such as the volatilization resistance coefficient of the penetrant. By constructing this database, a complete digital record of the entire process from defect detection to weld repair has been achieved, providing a data foundation for subsequent quality traceability and process analysis.

[0095] The central processing unit is the core logic control component of the system and is electrically connected to the workstation's sensors and heating control terminal.

[0096] During the welding process, status sensors installed around the welding torch or workpiece monitor the welding current, voltage, and wire feeding status in real time.

[0097] When an abnormal interruption signal is detected, the central processing unit immediately initiates an emergency response procedure. This procedure first indexes the corresponding defect to be repaired and its geometric parameters in the weld repair information database based on the current coordinate position of the welding torch.

[0098] Subsequently, the central processing unit performs calculations based on the aforementioned purification holding time calculation logic.

[0099] Specifically, the central processing unit uses the maximum depth of the current defect, the width of the surface opening, and the preset penetrant volatilization resistance coefficient to calculate the duration for which the target temperature needs to be maintained in the area before covering it with insulation material, i.e., the purification holding time.

[0100] The calculation logic follows that the purification holding time is proportional to the maximum depth and also proportional to the correction factor related to the aspect ratio of the defect (the ratio of the maximum depth to the surface opening width).

[0101] To address the lack of standardized operating procedures in existing technologies, the system is equipped with a welding repair operation guidance terminal, which runs dedicated welding repair operation guidance software (APP).

[0102] Welders or operators can use this terminal to view casting information and recommended welding repair strategies. In the event of an abnormal interruption, the terminal automatically switches to an emergency guidance interface. The interface displays a prompt "Please heat to 300-350℃ immediately" and shows a countdown of the purification holding time calculated by the central processing unit.

[0103] Simultaneously, the system integrates environmental and temperature monitoring functions. Temperature sensors (such as infrared temperature probes) collect the surface temperature of the interrupted area in real time and feed it back to the central processing unit. The central processing unit adjusts the power of the auxiliary heating device through a PID algorithm to ensure that the heating temperature remains stable within the set target temperature range, forming a closed-loop temperature control.

[0104] When the countdown ends, that is, after the purification and holding time is reached, the welding repair operation guidance terminal will issue a visual or audible alarm, prompting the operator to "immediately remove the heating device and cover it with asbestos cloth or other insulation materials".

[0105] This function ensures the accuracy of the timing of heat preservation intervention, avoiding problems such as incomplete removal of residue due to premature heat preservation or excessive heat loss due to excessive heat preservation. This auxiliary system transforms complex process calculations and control into intuitive operating instructions, reducing reliance on the operator's personal experience.

[0106] To further illustrate the specific application effects of the present invention, a specific embodiment is given below in conjunction with the production process of copper castings for aerospace engines.

[0107] The method of this invention is used in the production process of copper castings for aerospace engines.

[0108] First, a crack defect was detected on the surface of the casting using a dye penetrant and 3D scanning. The geometric parameters of the defect were measured and recorded by the system and entered into the database. Subsequently, an automated welding robot was used for repair.

[0109] When welding reached the middle of the crack, a sudden power outage in the workshop interrupted the welding process. At this point, the system immediately triggered the interruption handling procedure (or issued an instruction with backup power support). The operator (or automated auxiliary equipment) immediately followed step S3 to heat the weld area to the target temperature of 300°C and maintain it for the calculated purification holding time based on the crack's geometric parameters. After holding, asbestos cloth was used for insulation.

[0110] After power was restored, the asbestos cloth was removed according to step S4. Measurements showed the weld temperature had naturally cooled below the process requirements. The operator activated the heating device to preheat the weld to 280°C (the minimum interpass temperature in this case), and then continued welding until the crack was completely sealed. The weld temperature was monitored in real-time by sensors, and the computer automatically adjusted the heating power to ensure temperature stability. Final inspection showed the joint was free of porosity and cracks, meeting aerospace-grade quality standards.

[0111] In summary, the present invention provides a method for repairing weld defects in copper castings based on dye penetrant testing technology, overcoming the limitations of traditional dye penetrant testing as a single inspection process. This method establishes a direct mapping mechanism from defect geometry to heat treatment process parameters.

[0112] Specifically, by collecting two geometric parameters—the maximum depth of the defect and the width of the surface opening—the difficulty of escaping penetrant residues from deep defects can be precisely quantified. In the event of an abnormal interruption, this invention no longer employs conventional insulation measures, but instead calculates a precise purification and temperature holding time based on the aforementioned geometric parameters. By maintaining a specific target temperature for a calculated duration before covering with asbestos cloth or other insulation materials, the deep organic residues are forcibly vaporized and expelled using thermodynamic principles.

[0113] This proactive purification strategy, combined with subsequent passive insulation measures, not only mitigated the risk of cooling cracks in copper castings due to their high thermal conductivity but also completely eliminated the process hazard of weld porosity caused by residual colorant. Furthermore, the use of temperature-monitored resumption-of-work matching logic enabled high-quality repairs after welding interruptions, improving the process stability of copper casting welding repair operations.

Claims

1. A method for repairing weld defects in copper castings based on dye penetrant testing technology, characterized in that, Includes the following steps: S1. Using a three-dimensional scanning device, data is collected on the defects to be repaired on the surface of the copper casting after imaging with a dye penetrant. The maximum depth and surface opening width of the defects to be repaired are measured, and the maximum depth and surface opening width are defined as geometric parameters. S2. Use an arc welding torch to fill the defects to be welded in multiple layers and passes. When the welding operation is detected to have stopped, the state is defined as an abnormal interruption, and the area containing the unfused weld and heat-affected zone is identified as the interruption area to be processed. S3. Start the auxiliary heating device to heat the interrupted area to be treated and control it at the target temperature. Call the geometric parameters and calculate the purification holding time according to the purification holding time formula. Keep the auxiliary heating device on to maintain the interrupted area to be treated at the target temperature until the purification holding time is reached. Then remove the auxiliary heating device and use insulation material to tightly cover the interrupted area to be treated. S4. When conditions for resuming work are met, remove the insulation material, measure the instantaneous temperature of the weld surface, compare the instantaneous temperature with the minimum and maximum interpass temperatures, adjust the thermal state of the weld according to the comparison results, and start the arc welding gun to continue welding after the requirements are met, thereby obtaining the repaired copper casting.

2. The method for repairing weld defects in copper castings based on dye penetrant testing technology according to claim 1, characterized in that, In step S1, the specific process of data acquisition includes: The operator uses the 3D scanning equipment to acquire point cloud data of the defect to be welded and repaired, and extracts the maximum depth and the surface opening width by analyzing the point cloud data. The geometric parameters are then entered into the database module for use in step S3.

3. The method for repairing weld defects in copper castings based on dye penetrant testing technology according to claim 1, characterized in that, In step S2, the triggering conditions for abnormal interruption include power outages caused by environmental factors, shutdowns caused by equipment failures, or absences from duty caused by personnel factors. The abnormal interruption refers to the cessation of welding operations when the defects to be repaired have not been fully repaired and the process has not reached its end point. The conditions for resuming work refer to the elimination of the factors that caused the abnormal interruption, including power restoration, equipment troubleshooting, or personnel arrival.

4. The method for repairing weld defects in copper castings based on dye penetrant testing technology according to claim 1, characterized in that, In step S3, the target temperature ranges from 300 degrees Celsius to 350 degrees Celsius. The target temperature is preset based on the stress-relief annealing characteristics of the copper casting material and the physical boiling point of the organic solvent in the dye penetrant.

5. A method for repairing weld defects in copper castings based on dye penetrant testing technology according to claim 1, characterized in that, In step S3, the calculation logic determined by the purification holding time formula is as follows: The purification holding time is equal to the product of the penetrant evaporation resistance coefficient, the maximum depth, and the correction factor; The correction factor is equal to the value one plus the ratio of the maximum depth to the width of the surface opening; The volatilization resistance coefficient of the penetrant is a constant that is pre-determined based on the ease with which the dye penetrant volatilizes in the pores of the copper casting matrix.

6. A method for repairing weld defects in copper castings based on dye penetrant testing technology according to claim 5, characterized in that, The method for determining the volatilization resistance coefficient of the penetrant is as follows: Standard artificial defects are prefabricated on a test block made of the same material as the copper casting. After applying the same type of dyeing agent, the relationship between the time required for the residue to completely evaporate at the target temperature and the defect depth is determined, thereby obtaining the volatilization resistance coefficient of the penetrant.

7. A method for repairing weld defects in copper castings based on dye penetrant testing technology according to claim 1, characterized in that, In step S3, the auxiliary heating device includes a flame heating gun and an induction heater; The operator activates the auxiliary heating device to heat the interrupted area to be treated, causing the residual dye penetrant inside the defect to be welded to vaporize and be discharged to the surface of the copper casting.

8. A method for repairing weld defects in copper castings based on dye penetrant testing technology according to claim 1, characterized in that, In step S4, the specific logic for adjusting the thermal state of the weld is as follows: If the instantaneous temperature is less than the minimum interpass temperature, the auxiliary heating device is activated to reheat the weld until the instantaneous temperature rises back to between the minimum and maximum interpass temperatures. If the instantaneous temperature is greater than the maximum interlayer temperature, the operation is suspended and natural air cooling is carried out until the instantaneous temperature drops to between the minimum interlayer temperature and the maximum interlayer temperature. If the instantaneous temperature is between the minimum interpass temperature and the maximum interpass temperature, it is determined that the requirement is met, the current state is maintained, and the continued soldering is performed.

9. A method for repairing weld defects in copper castings based on dye penetrant testing technology according to claim 8, characterized in that, The minimum interpass temperature and the maximum interpass temperature are process parameters preset based on the welding procedure qualification document corresponding to the copper casting.

10. A method for repairing weld defects in copper castings based on dye penetrant testing technology according to claim 1, characterized in that, It also includes using a welding repair auxiliary system equipped with a central processing unit and a heating control terminal to assist in the execution of step S3, specifically: After receiving the abnormal interruption signal, the central processing unit automatically extracts the geometric parameters and calculates the purification holding time according to the purification holding time formula. The central processing unit sends instructions to the heating control terminal, which displays the purification holding time as a countdown to the operator, guiding the operator to remove the auxiliary heating device and cover the interrupted area to be treated with insulation material.

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