A method for repairing excessive clearance in a hydraulic piston pump piston assembly

Abstract

This invention relates to the field of hydraulic piston pump component repair technology, specifically a method for repairing excessive clearance in a hydraulic piston pump piston assembly. The specific steps are as follows: S1, measuring the piston assembly repair technical specifications; S2, removing material; S3, checking quality; S4, grinding repair; S5, cleaning; S6, lubrication; S7, closing the joint; S8, observing for cracks at the closing joint; S9, stress relief treatment; S10, checking clearance; S11, checking angle; S12, checking for jamming; S13, checking for cracks; S14, drilling and assembly; S15, running-in test; S16, disassembling the hydraulic piston pump; S17, use. The socket on the follower piston is removed using machining, and the wear marks on the ball head surface are repaired using spherical grinding technology. After removal, a new socket is closed onto the piston rod. The closed piston assembly meets the technical requirements for clearance, deflection angle, and rotational stability.

Description

Technical Field

[0001] This invention relates to the field of hydraulic piston pump component repair technology, specifically a method for repairing excessive clearance in a hydraulic piston pump piston assembly. Background Technology

[0002] Hydraulic piston pumps are the power source for aircraft hydraulic systems, using hydraulic oil as the working medium. These pumps are characterized by high supply pressure and large supply flow. One of the key components for regulating the high pressure and large flow of the hydraulic piston pump is the swashplate assembly, and the piston assembly is the key component for adjusting the angle of the swashplate assembly to regulate the oil supply. The socket 1 on the piston assembly 6 is connected to the swashplate 4 via pin 5. (See attached image for piston assembly details.) Figure 1 Swashplate components Figure 2 The socket on the piston assembly is a steel part. During normal operation of the hydraulic piston pump, the ball joint of the socket is constantly subjected to contact forces from loads such as adjusting pressure and return spring force. Therefore, wear will occur between the ball joint and the piston rod ball after long-term use, resulting in excessive clearance of the piston assembly, reduced service life, and consequently affecting the oil supply and pressure supply performance of the hydraulic piston pump. Therefore, a method for repairing excessive clearance in the piston assembly of a hydraulic piston pump was designed, which can effectively improve the service life of the piston assembly. Summary of the Invention

[0003] To address the aforementioned problems, this invention proposes a method for repairing excessive clearance in a hydraulic plunger pump piston assembly.

[0004] A method for repairing excessive clearance in a hydraulic plunger pump piston assembly, comprising the following specific steps:

[0005] S1. Measure the technical specifications for piston assembly repair: It must meet the specified requirements. If the piston assembly does not meet the requirements, then repair is not required.

[0006] S2. Material Removal: Using the dimensions of the piston rod ball head Φ12 and the side of socket 1 Φ14.5 as references, machine away material with a depth not exceeding 1.25mm from the side of the socket on the piston assembly. After machining, cut off the socket to avoid damaging the piston rod ball head due to destructive disassembly.

[0007] S3. Quality Inspection: Inspect the surface quality of the piston rod ball head. There should be no scratches or dents with a depth greater than 0.1mm on the surface.

[0008] S4. Grinding and Repair: Use spherical grinding to repair the working marks on the surface of the piston rod ball head. The grinding dimension should not exceed 0.1mm. The spherical grinding parameters are as follows:

[0009] ① Coarse grinding, grinding speed 150r / min, grinding paste particle size W7, surface roughness Ra after grinding 0.08~0.16μm;

[0010] ② Fine grinding, grinding speed 120r / min, grinding paste particle size W1, surface roughness Ra after grinding 0.01~0.02μm;

[0011] S5. Cleaning: Use an organic solvent to clean the surface of the piston rod ball head and then blow it dry;

[0012] S6. Lubrication: Apply No. 20 aviation lubricating oil to the spherical surface of the piston rod;

[0013] S7. Closing: Close the new socket to the piston rod;

[0014] S8. Check for cracks at the joint: Visually inspect the joint of the socket for cracks.

[0015] S9. Stress relief treatment: Perform aging stress relief treatment on the socket with the end cap;

[0016] S10. Check clearance: Check that the axial clearance between the socket and the piston rod is no more than 0.10mm. If it is not qualified, return to step S7 to re-close the joint.

[0017] S11. Check angle: Apply a force of no more than 1N to the part and check that the deflection angle of the socket is not less than 17°.

[0018] S12. Check for jamming: When an external extrusion force and tension of 10N are applied along the axis, check by hand whether the socket deflection angle rotates smoothly without any jamming or rattling sound.

[0019] S13. Check for cracks: The piston assembly should be free of cracks when inspected by magnetic particle testing.

[0020] S14. Drilling and assembly: Drill holes in the piston assembly, assemble it onto the swashplate using pins, and check that the ball head rotates smoothly without any sticking or rattling noise.

[0021] S15. Break-in test: The swash plate assembly is fitted with a hydraulic piston pump and a break-in test is conducted for no less than 6 hours.

[0022] S16. Disassemble the hydraulic piston pump: Check that the ball head rotates smoothly without jamming or grinding noise, and that the clearance does not increase.

[0023] S17. Use: Piston assemblies that have passed the above repairs shall be put into use.

[0024] As a further improvement to the present invention, step S1 has the following specific requirements:

[0025] The ovality of the piston's Φ20 dimension is no greater than 0.055mm;

[0026] The taper of the piston's Φ20 dimension is no greater than 0.055mm;

[0027] The clearance at the connection between the piston and piston rod 2 shall not exceed 0.08 mm;

[0028] The piston deflects at an angle of not less than 5° in any direction.

[0029] As a further improvement of the present invention, step S3 shall not allow damage to the piston rod ball head greater than 0.1 mm or irreparable damage due to machining reasons.

[0030] As a further improvement of the present invention, the roundness of the ball head after grinding in step S4 is no greater than 0.001mm. During grinding, the piston rod clamp and the ball head grinding rod rotate simultaneously along their respective axes to ensure uniform and stable grinding.

[0031] As a further improvement of the present invention, step S7 requires ensuring that the closing size Φ14.6 +0.2 mm.

[0032] As a further improvement of the present invention, the stress relief treatment in step S9 is carried out at a temperature of 140℃±10℃, held for 240~260min, and then air-cooled.

[0033] The beneficial effects of this invention are:

[0034] This invention uses machining to remove the socket on the follower piston, and uses spherical grinding technology to repair the wear marks on the ball head surface. After cutting, the replacement socket is closed onto the piston rod. The piston assembly after closure meets various technical requirements such as clearance, deflection angle, and rotational stability. This invention does not change the strength of other structural parts. Accelerated life testing is carried out on the repaired piston assembly, and the clearance change trend is measured to ensure the reliability of the repaired part and meet the usage requirements. Attached Figure Description

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] Figure 1 This is a three-dimensional structural diagram of the piston assembly of the present invention;

[0037] Figure 2 This is a schematic diagram of the three-dimensional structure of the socket of the present invention;

[0038] Figure 3 This is a three-dimensional structural diagram of the piston rod of the present invention;

[0039] Figure 4 This is a schematic diagram of the swashplate assembly structure of the present invention;

[0040] Figure 5 This is a schematic diagram of the process structure of the present invention. Detailed Implementation

[0041] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below.

[0042] like Figures 1 to 5 As shown, a method for repairing excessive clearance in a hydraulic plunger pump piston assembly includes the following specific steps:

[0043] S1. Measure the technical specifications for repairing piston assembly 6: It must meet the specified requirements. If piston assembly 6 does not meet the requirements, then repair is not required.

[0044] S2. Material Removal: Using the dimensions of the piston rod 2 ball head Φ12 and the socket 1 side Φ14.5 as references, machine away material with a depth not exceeding 1.25mm from the side of the socket 1 on the piston assembly 6. After machining, cut off the socket 1 to avoid damaging the ball head of the piston rod 2 due to destructive disassembly.

[0045] S3. Quality Inspection: Inspect the surface quality of the piston rod ball head 2. There should be no scratches or dents with a depth greater than 0.1mm on the surface.

[0046] S4. Grinding and Repair: Use spherical grinding to repair the working marks on the surface of the piston rod 2 ball head. The grinding dimension should not exceed 0.1mm. The spherical grinding parameters are as follows:

[0047] ① Coarse grinding, grinding speed 150r / min, grinding paste particle size W7, surface roughness Ra after grinding 0.08~0.16μm;

[0048] ② Fine grinding, grinding speed 120r / min, grinding paste particle size W1, surface roughness Ra after grinding 0.01~0.02μm;

[0049] S5. Cleaning: Use an organic solvent to clean and dry the surface of the piston rod 2 ball head;

[0050] S6. Lubrication: Apply No. 20 aviation lubricating oil to the spherical surface of piston rod 2;

[0051] S7. Closing: Close the new socket 1 to the piston rod 2;

[0052] S8. Observe whether there are cracks at the sealing edge: Visually inspect the sealing edge of socket 1 to find no cracks;

[0053] S9. Stress relief treatment: Perform aging stress relief treatment on the closed socket 1;

[0054] S10. Check clearance: Check that the axial clearance between socket 1 and piston rod 2 is no more than 0.10mm. If it is not qualified, return to step S7 to re-close the joint.

[0055] S11. Check angle: Apply a force of no more than 1N to the part and check that the deflection angle of socket 1 is not less than 17°.

[0056] S12. Check for jamming: When an external extrusion force and tension of 10N are applied along the axis, check by hand whether the deflection angle of socket 1 rotates smoothly without any jamming or rattling sound.

[0057] S13. Check for cracks: Piston assembly 6 should be free of cracks when inspected by magnetic particle testing.

[0058] S14. Drilling and assembly: Drill holes in piston assembly 3, and assemble it onto swashplate 4 using pin 5. Check that the ball head rotates smoothly without any jamming or rattling noise.

[0059] S15. Break-in test: The swash plate assembly is fitted with a hydraulic piston pump and a break-in test is conducted for no less than 6 hours.

[0060] S16. Disassemble the hydraulic piston pump: Check that the ball head rotates smoothly without jamming or grinding noise, and that the clearance does not increase.

[0061] S17. Use: Piston assemblies that have passed the above repairs shall be put into use.

[0062] The specific requirements for step S1 are as follows:

[0063] The ovality of the Φ20 dimension of piston 3 is no greater than 0.055mm;

[0064] The taper of the Φ20 dimension of piston 3 is no greater than 0.055mm;

[0065] The clearance at the connection between piston 3 and piston rod 2 shall not exceed 0.08 mm;

[0066] The piston 3 deflects at an angle of not less than 5° in any direction, as shown in the following table:

[0067] Serial Number Repair technical specifications description Repair technical specifications requirements 1 Φ20 ovality of piston 3 No larger than 0.055mm 2 Piston 3 Φ20 taper No larger than 0.055mm 3 Clearance at the connection between piston 3 and piston rod 2 No larger than 0.08mm 4 Piston 3 deflects in any direction by an angle Not less than 5°

[0068] Step S3 shall not allow damage greater than 0.1 mm or irreparable damage to the ball head of piston rod 2 due to machining reasons.

[0069] After grinding in step S4, the roundness of the ball head is no greater than 0.001mm. During grinding, the piston rod clamp and the ball head grinding rod rotate simultaneously along their respective axes to ensure uniform and stable grinding. The socket 1 on the follower piston 2 is removed by mechanical processing. The wear marks on the surface of the ball head are repaired by spherical grinding technology. After cutting, the new socket is closed onto the piston rod 3.

[0070] Step S7 requires ensuring the closing size is Φ14.6. +0.2mm, the piston assembly 6 after the end is closed meets various technical requirements such as clearance, deflection angle and rotational smoothness.

[0071] By repairing the excessive clearance at socket 1 of piston assembly 6, the dimensions of piston assembly 6 are restored to improve its service life, and the repaired piston assembly can meet the assembly requirements and the installation and use requirements of aircraft hydraulic piston pumps.

[0072] The stress relief treatment in step S9 is carried out at a temperature of 140℃±10℃, held for 240~260min, and then air-cooled.

[0073] The main technical indicators for repair during and after the repair process are shown in the table below:

[0074]

[0075]

[0076] This invention does not alter the strength of other structural components. Accelerated life testing of the repaired piston assembly 6 and measurement of clearance variation trends ensure the reliability of the repaired components and meet usage requirements.

[0077] 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 to the above embodiments. The embodiments and descriptions in the specification are merely prisms of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for repairing excessive clearance in a hydraulic plunger pump piston assembly, characterized in that: The specific steps are as follows: S1. Measure the technical indicators for repairing the piston assembly (6): It needs to meet the specified requirements. If the piston assembly (6) does not meet the requirements, it does not need to be repaired. S2. Material removal: Taking the dimensions of the piston rod (2) ball head Φ12mm and the socket (1) side Φ14.5mm as reference, machine away the material on the side of the socket (1) on the piston assembly (6) with a depth not greater than 1.25mm. After machining, cut off the socket (1) to avoid damaging the ball head of the piston rod (2) due to destructive decomposition. S3. Quality inspection: Inspect the surface quality of the piston rod (2) ball head. There should be no scratches or dents with a depth greater than 0.1mm on the surface. S4. Grinding and Repair: The working marks on the surface of the piston rod (2) ball head are ground and repaired using the spherical grinding method. The grinding size is no more than 0.1 mm. S5. Cleaning: Use an organic solvent to clean and dry the surface of the piston rod (2) ball head; S6. Lubrication: Apply No. 20 aviation lubricating oil to the spherical surface of the piston rod (2); S7. Closing: Close the new socket (1) onto the piston rod (2); S8. Observe whether there are cracks at the end: Visually inspect the socket (1) and find no cracks at the end; S9. Stress relief treatment: Perform aging stress relief treatment on the socket (1) with the end closed; S10. Check clearance: Check that the clearance between the socket (1) and the piston rod (2) along the axial direction is no more than 0.10 mm. If it is not qualified, return to step S7 to re-close the joint. S11, Check angle: Apply a force of no more than 1 N to the part and check that the deflection angle of the socket (1) is no less than 17°; S12. Check for jamming: When the external extrusion force and tension along the axis reach 10 N, check by hand whether the socket (1) deflection angle rotates smoothly without jamming or rattling sound. S13. Check for cracks: Magnetic particle inspection of piston assembly (6) should show no cracks; S14. Drilling and assembly: Drill holes in the socket (1), and use pins (5) to assemble it onto the swashplate (4). Check that the ball head rotates smoothly without any jamming or rattling noise. S15. Break-in test: The swash plate assembly is fitted with a hydraulic piston pump and a break-in test is conducted for no less than 6 hours. S16. Disassemble the hydraulic piston pump: Check that the ball head rotates smoothly without jamming or grinding noise, and that the clearance does not increase. S17. Use: Piston assemblies that have passed the above repairs shall be put into use. The specific requirements for step S1 are as follows: The ellipticity of the Φ20 dimension of the piston (3) is not greater than 0.055mm; The taper of the Φ20 dimension of the piston (3) is not greater than 0.055mm; The clearance at the connection between piston (3) and piston rod 2 shall not exceed 0.08 mm; The piston (3) deflects at an angle of not less than 5° in any direction.

2. The method for repairing excessive clearance in a hydraulic plunger pump piston assembly according to claim 1, characterized in that: Step S3 shall not allow damage greater than 0.1 mm or irreparable damage to the ball head of the piston rod (2) due to machining reasons.

3. The method for repairing excessive clearance in a hydraulic plunger pump piston assembly according to claim 1, characterized in that: After grinding in step S4, the roundness of the ball head is no greater than 0.001mm. During grinding, the piston rod clamp and the ball head grinding rod rotate simultaneously along their respective axes.

4. The method for repairing excessive clearance in a hydraulic plunger pump piston assembly according to claim 1, characterized in that: The spherical grinding parameters required in step S4 are as follows: Coarse grinding was performed at a grinding speed of 150 r / min with a grinding paste particle size of W7, resulting in a surface roughness of Ra of 0.08–0.16 μm.

5. The method for repairing excessive clearance in a hydraulic plunger pump piston assembly according to claim 1, characterized in that: The spherical grinding parameters in step S4 are as follows: fine grinding, grinding speed 120 r / min, grinding paste particle size W1, and surface roughness Ra 0.01~0.02 μm after grinding.

6. The method for repairing excessive clearance in a hydraulic plunger pump piston assembly according to claim 1, characterized in that: Step S7 requires ensuring the closing size is Φ14.

6. +0.2 mm.

7. The method for repairing excessive clearance in a hydraulic plunger pump piston assembly according to claim 1, characterized in that: The stress relief treatment in step S9 is carried out at a temperature of 140℃±10℃, held for 240~260min, and then air-cooled.

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