A Method for Defect Detection and Reliability Verification of Diffusion Welding of Hydraulic Pump Slipper Shoes

Abstract

The present invention relates to the technical field of hydraulic pump repair, and specifically to a method for detecting defects and verifying the reliability of diffusion welding of hydraulic pump slippers, which includes the following steps: By comparing various internal defect detection methods, industrial CT scanning is determined as the detection method for detecting internal defects in the diffusion welding of hydraulic pump slippers, and the optimal scanning parameters are determined through multiple verifications of scanning parameters; Use industrial CT scanning to scan and detect internal defects in the hydraulic pump slipper. After scanning, all pores with an equivalent diameter greater than 0.15 mm are counted and classified into safe hydraulic pump slippers and non-compliant hydraulic pump slippers; Finite element modeling and performance simulation verification are carried out on non-compliant hydraulic pump slippers. The present invention conducts engineering verification on the service reliability of the diffusion welding of hydraulic pump slippers. The adopted internal defect detection method and analysis process are innovative, can effectively detect defects not identified during the manufacturing process, and improve the service reliability of the repaired products.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic pump repair, and particularly to a method for detecting defects and verifying the reliability of diffusion welding of hydraulic pump slippers. Background Art

[0002] Bimetal diffusion welding has been widely used in the production and manufacturing of hydraulic pump parts. For example, the diffusion welding process of tin bronze and structural steel is adopted on the surface of the hydraulic pump slipper head, which not only meets the matching of the friction pair of the parts but also improves the overall strength of the material, avoiding problems such as easy pulling off due to the low strength of the base material, and effectively improving the lubrication performance and service life of the hydraulic pump. However, in fact, there are defects such as pores and voids inside the diffusion welding of the hydraulic pump slipper, which have caused many cases of copper layer chipping and peeling of the hydraulic pump slipper, resulting in wear failure of the hydraulic pump.

[0003] At present, the internal defects of the hydraulic pump slipper are mainly detected by ultrasonic inspection of the flat blank parts. However, ultrasonic inspection is only applicable to the diffusion welding blank parts without machined convex grooves and bosses, and the machined hydraulic pump slippers cannot be inspected. Moreover, this method does not consider the influence of machining on defects, nor does it verify the influence on the use reliability of the hydraulic pump, seriously affecting the use and repair work of the hydraulic pump.

[0004] Therefore, during the repair process of the hydraulic pump, it is necessary to further check the internal defects of the diffusion welding and give a qualified judgment for use.

[0005] Through literature research, there are few reliability studies on the interface defects of the diffusion welding of hydraulic pump slippers at present. The present invention provides an effective and intuitive detection method and standard for the internal defects of the diffusion welding of hydraulic pump slippers from an engineering perspective; through engineering research and experimental verification, a method and process for verifying the use reliability of large pores and voids in the diffusion welding layer of hydraulic pump slippers are given. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention proposes a method for detecting defects and verifying the reliability of diffusion welding of hydraulic pump slippers.

[0007] The technical problems to be solved by the present invention are realized by adopting the following technical solutions:

[0008] A method for detecting defects and verifying the reliability of diffusion welding of hydraulic pump slippers includes the following steps:

[0009] Step (1) By comparing various internal defect detection methods, industrial CT scanning is determined as the detection method for detecting the internal defects of the diffusion welding of hydraulic pump slippers, and through calibration of multiple scanning parameters, the optimal scanning parameters are determined;

[0010] Step (2) Based on the requirements in the design and manufacturing process of the hydraulic pump that 80% of the pore diameters on the surface of the hydraulic pump slipper are not greater than 0.15 mm, the requirement that the internal defects in the blank parts before processing the hydraulic pump slipper are not greater than 1.0 mm, the shape, size, product material of the hydraulic pump slipper, and the detection accuracy requirements of the industrial CT scanning equipment, it is determined to select defects with an equivalent diameter greater than 0.15 mm, and the equivalent pore diameter greater than 1.0 mm is defined as an over-standard defect as the scope definition of the defect, which is used for the comparison and selection of the defect samples of the hydraulic pump slipper during the repair process;

[0011] Step (3) Use industrial CT scanning to detect the internal defects of the hydraulic pump slipper. After scanning, count all pores with an equivalent diameter greater than 0.15 mm and define and display them as safe hydraulic pump slippers and over-standard hydraulic pump slippers;

[0012] Step (4) Conduct finite element modeling and performance simulation verification on the over-standard hydraulic pump slippers;

[0013] Step (5) According to the simulation verification results, formulate a reliability test plan, conduct a reliability test, and record the test results;

[0014] Step (6) Based on the change trends of the oil supply and return oil volumes of the hydraulic pump and the recorded test results, comprehensively judge and give a reliability conclusion.

[0015] Preferably, in step (1), the multiple internal defect detection methods specifically include X-ray detection, ultrasonic C-scan, and industrial CT scanning.

[0016] Preferably, the multiple scanning parameters in step (1) are specifically 10 times, and the optimal scanning parameters are specifically: voltage 230 KV, current 200 - 210 μA, resolution 20 μm.

[0017] Preferably, in step (3), the hydraulic pump slippers with the maximum dimension of the equivalent internal defect diameter less than 1.0 mm are defined as safe hydraulic pump slippers, and the hydraulic pump slippers with the maximum dimension of the equivalent internal defect diameter greater than 1.0 mm are defined as over-standard hydraulic pump slippers.

[0018] Preferably, the process of finite element modeling and performance simulation verification in step (4) is as follows:

[0019] (a) Using the analysis of industrial CT scan data, select the largest internal defect sample according to the shape and position of the larger defects near the diffusion welding layer of the hydraulic pump slipper;

[0020] (b) Define a path for the large defects in the sample, establish a finite element model. According to the metallographic analysis of diffusion welding, the depth of metal diffusion welding is about 0.1 mm. When prefabricating defects in the finite element model, with the bonding surface as the reference, dig out a 0.1 mm defect into the copper layer;

[0021] (c) Define the material properties of the slipper of the hydraulic pump;

[0022] (d) Calculate the calculated load of the operating state of the slipper of the physical hydraulic pump;

[0023] (e) Set the contact form and apply the load boundary;

[0024] (f) Use cohesive elements to simulate the diffusion welding metallurgical bonding layer, select the quadratic tension criterion for the damage evolution criterion, analyze the stress of the defect interface, the numerical values of the radial and circumferential Mises stresses at the defect boundary, and the distribution of the damage criterion of the bonding layer, and determine whether the performance of the slipper of the sample hydraulic pump meets the requirements of tensile and shear strengths;

[0025] (g) Verify through simulation whether the maximum sample of the given internal defect meets the usage requirements.

[0026] Preferably, the specific process of the reliability test plan in step (five) is as follows:

[0027] (A) Select the specimen sample according to the simulation verification result;

[0028] (B) Assemble the slipper of the test sample hydraulic pump into the hydraulic pump;

[0029] (C) Conduct a performance test to check the comprehensive performance of the hydraulic pump to ensure that the performance is qualified after the hydraulic pump is assembled;

[0030] (D) For the model of the test hydraulic pump, carry out an accelerated life test: record the detection parameters every 20 h when the inlet pressure is 0.25 + 0.03 0 MPa;

[0031] (E) Conduct a performance check after the accelerated life test to check whether the performance of the sample hydraulic pump is qualified;

[0032] (F) Conduct a disassembly inspection after the test to check for wear;

[0033] (G) Conduct another industrial CT scan to check whether the internal defects of the slipper of the sample hydraulic pump have expanded;

[0034] (H) Record the results of the performance inspection, the results of the disassembly inspection, and the results of the industrial CT scan.

[0035] Preferably, the detection parameters in step (D) include rotational speed, inlet working fluid temperature, outlet pressure, oil supply amount, and oil return amount.

[0036] The beneficial effects of the present invention are:

[0037] The present invention has carried out engineering verification on the reliability of the diffusion welding of the slipper of a hydraulic pump. The internal defect detection method and analysis process adopted are innovative, which can effectively detect the defects not identified in the manufacturing process and improve the reliability of the repaired product. Description of the Drawings

[0038] The present invention will be further described below with reference to the drawings and embodiments:

[0039] Figure 1 is the maximum defect sample of the slipper of the hydraulic pump;

[0040] Figure 2 is a schematic diagram of the defect model of the slipper of the hydraulic pump;

[0041] Figure 3 is the accelerated life test load spectrum in the present invention;

[0042] Figure 4 is the change diagram of the oil supply and return oil volumes of the hydraulic pump at 27.1 MPa in the present invention;

[0043] Figure 5 is the change diagram of the return oil volume of the hydraulic pump at zero flow rate of 30.0 MPa in the present invention;

[0044] Figure 6 is a schematic diagram of the inspection of the maximum defect of the sample before and after the test in the present invention. Detailed Embodiments

[0045] In order to make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the present invention will be further elaborated below with reference to the drawings and embodiments.

[0046] A method for detecting defects and verifying the reliability of the diffusion welding of the slipper of a hydraulic pump includes the following steps:

[0047] Step (1): Through the comparison of three common internal penetration non-destructive detections, namely X-ray detection, ultrasonic C-scan, and industrial CT scan, it is determined that industrial CT scan can effectively detect the position, size, and distribution of the internal defects of the diffusion welding of parts and present them in three-dimensional visualization. Through the verification of 10 sets of scanning parameters, the optimal scanning parameters are determined, which can improve the scanning efficiency. Specifically, the optimal scanning parameters are: voltage 230 KV, current 200 - 210 μA, and resolution 20 μm.

[0048] Step (2) Referring to the requirements for the hydraulic pump slipper during its design and manufacturing process, where 80% of the pore diameters on the surface of the hydraulic pump slipper are not greater than 0.15 mm, the internal defects in the blank parts before processing the hydraulic pump slipper are not greater than 1.0 mm, the shape, size, product material of the hydraulic pump slipper, and the detection accuracy requirements of the industrial CT scanning equipment, ignoring pores with an equivalent diameter less than 0.15 mm can reduce the statistical workload. When scanning, defects with an equivalent diameter greater than 0.15 mm are selected, and pores with an equivalent diameter greater than 1.0 mm are defined as over-standard defects for the scope definition of defects, which is used for the comparison and selection of defect samples of the hydraulic pump slipper during the repair process.

[0049] Step (3) Use industrial CT scanning to detect the internal defects of the hydraulic pump slipper. After scanning, count and display all pores with an equivalent diameter greater than 0.15 mm. Define the hydraulic pump slipper with the maximum internal defect equivalent diameter less than 1.0 mm as a safe hydraulic pump slipper; define the hydraulic pump slipper with the maximum internal defect equivalent diameter greater than 1.0 mm as an over-standard hydraulic pump slipper, and mark all voids with sizes greater than 1.0 mm and similar void sizes and positions.

[0050] Step (4) Conduct finite element modeling and performance simulation verification on the over-standard hydraulic pump slipper. Specifically,

[0051] (a) Using the analysis of industrial CT scan data, select the largest internal defect sample according to the shape and position of the larger defects near the diffusion welding layer of the hydraulic pump slipper. As Figure 1 shown in the scanned maximum defect sample of the hydraulic pump slipper, the pores (white parts) are mostly concentrated on one side of the edge, and there are large areas of pores in patches (equivalent to non-welded areas).

[0052] (b) Define the path for the large defects in the sample, establish a finite element model. According to the metallographic analysis of diffusion welding, the depth of metal diffusion welding is about 0.1 mm. When prefabricating defects in the finite element model, based on the bonding surface, dig out a 0.1 mm defect towards the copper layer. The model is as Figure 2 shown.

[0053] (c) Define the material properties of the hydraulic pump slipper.

[0054] (d) Calculate the operating state calculation load of the physical hydraulic pump slipper.

[0055] (e) Set the contact form and apply the load boundary.

[0056] (f) Use cohesive elements to simulate the diffusion welding metallurgical bonding layer, select the quadratic tension criterion for the damage evolution criterion, analyze the stress at the defect interface, the radial and circumferential Mises stress values at the defect boundary, and the distribution of the bonding layer damage criterion to determine whether the performance of the sample hydraulic pump slipper meets the tensile and shear strength requirements.

[0057] (g) Verify whether the maximum sample of the given internal defect meets the usage requirements through simulation.

[0058] Step (5) According to the simulation verification results, formulate a reliability test plan, conduct a reliability test, and record the test results. Specifically,

[0059] (A) Select a specimen sample according to the simulation verification results.

[0060] (B) Assemble the test sample hydraulic pump slipper into the hydraulic pump.

[0061] (C) Conduct a performance test to check the comprehensive performance of the hydraulic pump and ensure that the performance of the assembled hydraulic pump is qualified.

[0062] (D) For the type of the test hydraulic pump, carry out an accelerated life test: every 20 h, record the detection parameters when the inlet pressure is 0.25 + 0.03 0 MPa. The detection parameters include rotational speed, inlet working fluid temperature, outlet pressure, oil supply volume, and oil return volume. As Figure 3 shown, it is the accelerated life load spectrum of the test hydraulic pump. As Figure 4 and 5 shown, they are the change trends of the oil supply volume and the oil return volume during the accelerated test, and each performance parameter meets the requirements in Table 1 below.

[0063] Table 1 Performance parameters of the hydraulic pump

[0064] Rotational speed r / min Working fluid temperature °C Outlet pressure (MPa) Oil supply volume (L / min) Measured value Oil return volume (L / min) Measured value 4200 +125 27.1 ≥215 ≤25 4200 +125 30±1 0 ≤25

[0065] (E) Conduct a performance check after the accelerated life test to check whether the performance of the sample hydraulic pump is qualified.

[0066] (F) Conduct a disassembly inspection after the test to check for wear.

[0067] (G) Conduct an industrial CT scan again to check whether the internal defects of the sample hydraulic pump slipper have expanded. As Figure 6 shown, there is no expansion at the maximum internal defect before and after the test.

[0068] (H) Record the results of the performance inspection, the results of the disassembly inspection, and the results of the industrial CT scan.

[0069] Step (6) According to the change trends of the oil supply volume and the oil return volume of the hydraulic pump. Specifically, the oil supply volume of the hydraulic pump reflects the product performance, the oil return volume reflects the microscopic wear of the friction pair, a large amount of wear leads to an increase in the oil return volume, and based on the disassembly inspection results, comprehensively judge and give a reliability conclusion.

[0070] The present invention has carried out engineering verification on the reliability of the diffusion welding of the slipper of a hydraulic pump. The internal defect detection method and analysis process adopted are innovative, which can effectively detect the defects not identified in the manufacturing process and improve the reliability of the repaired product during use.

[0071] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification is only the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and all these changes and improvements fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for defect detection and reliability verification of a slipper of a hydraulic pump, characterized in that: It includes the following steps: Step (1): Through the comparison of various internal defect detection methods, industrial CT scanning is determined as the detection method for detecting internal defects in the diffusion welding of the slipper of the hydraulic pump. Through the verification of multiple scanning parameters, the optimal scanning parameters are determined; Step (2): Referring to the requirements in the design and manufacturing process of the hydraulic pump that 80% of the pore diameters on the surface of the slipper of the hydraulic pump are not greater than 0.15 mm, the internal defects in the blank parts before processing the slipper of the hydraulic pump are not greater than 1.0 mm, the shape, size, product material of the slipper of the hydraulic pump, and the detection accuracy requirements of the industrial CT scanning equipment, it is determined to select defects with an equivalent diameter greater than 0.15 mm, and the equivalent pore diameter greater than 1.0 mm is defined as an over-standard defect as the scope definition of the defect, which is used for the comparison and selection of the defect samples of the slipper of the hydraulic pump during the repair process; Step (3): Use industrial CT scanning to scan and detect the internal defects of the slipper of the hydraulic pump. After scanning, count all the pores with an equivalent diameter greater than 0.15 mm and define and display them as safe hydraulic pump slippers and over-standard hydraulic pump slippers; [[ID=!]]Step (4): Conduct finite element modeling and performance simulation verification on the over-standard hydraulic pump slippers; Step (5): According to the simulation verification results, formulate a reliability test plan, conduct a reliability test, and record the test results; Step (6): According to the change trends of the oil supply and return oil volumes of the hydraulic pump and the recorded test results, comprehensively judge and give a reliability conclusion.

2. A method for defect detection and reliability verification of a slipper of a hydraulic pump by diffusion welding, characterized in that: The various internal defect detection methods in Step (1) specifically include X-ray detection, ultrasonic C-scan, and industrial CT scanning.

3. A method for defect detection and reliability verification of a slipper of a hydraulic pump by diffusion welding, characterized in that: The multiple scanning parameters in Step (1) are specifically 10 times, and the optimal scanning parameters are specifically: voltage 230 KV, current 200 - 210 μA, resolution 20 μm.

4. A method for defect detection and reliability verification of a slipper of a hydraulic pump by diffusion welding, characterized in that: In Step (3), the hydraulic pump slippers with the maximum size of the equivalent diameter of the internal defect less than 1.0 mm are defined as safe hydraulic pump slippers, and the hydraulic pump slippers with the maximum size of the equivalent diameter of the internal defect greater than 1.0 mm are defined as over-standard hydraulic pump slippers.

5. A method for defect detection and reliability verification of a slipper of a hydraulic pump by diffusion welding, characterized in that: The process of finite element modeling and performance simulation verification in Step (4) is as follows: (a) Using the analysis of industrial CT scanning data, select the largest internal defect sample according to the shape and position of the larger defects near the diffusion welding layer of the slipper of the hydraulic pump; (b) Define the path for the large defects in the sample, establish a finite element model. According to the metallographic analysis of diffusion welding, the depth of metal diffusion welding is about 0.1 mm. When prefabricating defects in the finite element model, with the bonding surface as the reference, dig out a 0.1-mm defect into the copper layer; (c) Define the material properties of the slipper of the hydraulic pump; (d) Calculate the operating state calculation load of the physical slipper of the hydraulic pump; (e) Set the contact form and apply the load boundary; (f) Use cohesive elements to simulate the diffusion welding metallurgical bonding layer, select the quadratic tension criterion as the damage evolution criterion, analyze the stress at the defect interface, the radial and circumferential Mises stress values at the defect boundary, and the distribution of the damage criterion of the bonding layer, and determine whether the performance of the sample hydraulic pump slippers meets the requirements of tensile and shear strengths; (g) Verify through simulation whether the given largest internal defect sample meets the usage requirements.

6. A method for defect detection and reliability verification of a slipper of a hydraulic pump by diffusion welding, characterized in that: The specific process of the reliability test plan in Step (5) is as follows: (A)Select the specimen samples according to the simulation verification results; (B)Assemble the test sample hydraulic pump slipper into the hydraulic pump; (C)Conduct performance tests to check the comprehensive performance of the hydraulic pump and ensure that the performance is qualified after assembly; (D) Conduct an accelerated life test for the model of the test hydraulic pump: Record the detection parameters every 20 h when the inlet pressure is 0.25 +0.03 0 MPa; (E)Conduct performance inspections after the accelerated life test to check whether the performance of the sample hydraulic pump is qualified; (F)Conduct disassembly inspections after the test to check for wear; (G)Perform industrial CT scans again to check whether the internal defects of the sample hydraulic pump slipper have expanded; (H)Record the results of performance inspections, disassembly inspections, and industrial CT scans.

7. A method for defect detection and reliability verification of a slipper of a hydraulic pump by diffusion welding, characterized in that: The detection parameters in step (D) include rotational speed, inlet working fluid temperature, outlet pressure, oil supply volume, and oil return volume.

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