A method for repairing the inner wall damage of a beryllium bronze piston part

Abstract

The present application relates to the technical field of remanufacturing, in particular to a beryllium bronze piston part inner wall damage repairing method, and its specific steps are as follows: S1, defect inspection; S2, electrode rod preparation; S3, electric spark coating repair; S4, cold welding machine remelting; S5, heat treatment; S6, inner hole honing; S7, repair verification; The present application adopts the method of electric spark coating repair + cold welding composite repair, which not only solves the problem of electric spark coating repair layer being not dense, but also solves the problem of difficult wire feeding in the cold welding inner hole repair process, and the specially-made electrode rod solves the problem of shaking of the long electrode rod rotating at high speed in the electric spark coating repair process, the metallographic of the repair layer does not have cracks and un-melted defects, the repair layer is metallurgically combined with the matrix, and the hardness of the repair layer reaches more than 90% of the matrix.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of remanufacturing, and particularly relates to a beryllium bronze piston part inner wall damage repairing method. BACKGROUND

[0002] Beryllium bronze has excellent properties such as high strength, hardness, wear resistance, corrosion resistance and elastic limit, and is widely used in the fields of aerospace and electronics.

[0003] The beryllium bronze piston part is used for telescopic actuating parts of aviation equipment and transmits hydraulic power. After long-term service, the inner wall of the part is worn and damaged by repeated friction of a plunger.

[0004] The inner diameter of the beryllium bronze piston part is 20-30 mm, and the conventional means cannot repair it. If a laser inner hole repairing process is used, the technology bottleneck of miniaturization of the inner hole laser head limits the equipment to only extend into an inner hole with a diameter of more than 30 mm. For the beryllium bronze piston part with a diameter of less than 30 mm, the laser inner hole repairing equipment has no repairing capacity. If a conventional inner hole welding is used, the beryllium on the surface of the beryllium bronze is easy to react with oxygen to generate beryllium oxide with high volatility, which affects the welding forming quality and produces a large number of defects. In addition, the inner hole welding is very inconvenient for wire feeding. Moreover, a large heat input can cause deformation of the part and make it unusable. If an electric spark coating process is used, the formed repairing layer has a large number of defects and cannot meet the use requirements.

[0005] There is no related research on the beryllium bronze piston part inner wall damage repairing. SUMMARY

[0006] In order to solve the above problems, the application provides a beryllium bronze piston part inner wall damage repairing method.

[0007] A beryllium bronze piston part inner wall damage repairing method has the following specific steps:

[0008] S1, defect inspection:

[0009] Visual inspection is performed on the beryllium bronze piston part to find the damage position, and the bottom of the beryllium bronze piston part has a small hole.

[0010] S2, electrode rod preparation:

[0011] A hot-rolled QBe2 beryllium bronze rod is subjected to heat treatment, and the rod after heat treatment is subjected to turning processing to prepare an electrode rod. The composition of the electrode rod comprises a coating section, a middle diameter fixed section, a coarse diameter fixed section and a clamping section.

[0012] S3, electric spark coating repairing:

[0013] Clamping the clamping section of the prepared electrode rod on the welding gun of the electric spark surfacing machine, using the electric spark surfacing machine to perform electric spark coating repair on the inner hole damage site, and using the outer groove vernier caliper to measure the wall thickness of the repaired site, when the wall thickness of the repaired site is greater than the thickness of the part by 100 μm, the electric spark coating repair is stopped;

[0014] S4, cold welding machine remelting:

[0015] Using the cold welding machine equipment, the cold welding machine welding gun is inserted into the inner wall damage site repaired by the electric spark coating, the damage site is remelted, and a dense repair layer is obtained;

[0016] S5, heat treatment:

[0017] The part treated in step S4 is placed into a vacuum heat treatment furnace for heat treatment, vacuumized to below 1 pa, then argon is filled to 0.1 MPa for heat treatment, and the furnace is cooled to room temperature before being taken out;

[0018] S6, honing of the inner hole:

[0019] The inner hole is honed to remove the protruding part of the inner wall repair position;

[0020] S7, repair verification:

[0021] After the same material and the same heat treatment state of the beryllium bronze piston part are repaired by the electric spark coating in step S3 and the cold welding machine remelting in step S4, the metallography and hardness of the repaired site are detected:

[0022] a. If no cracks and unmelted defects are observed in the metallography, the metallurgical bonding between the repair layer and the plate substrate is observed, and the hardness of the repair layer and the plate substrate is detected;

[0023] b. If the hardness of the repair layer reaches 90% of the hardness of the plate substrate, the beryllium bronze piston part repaired by steps 1-6 is determined to be qualified.

[0024] The heat treatment process of step S2 is: 770-790℃ for 1-2h water cooling, followed by 310-320℃ for 2-4h air cooling.

[0025] The electrode rod of step S2 is a rotary body, wherein the diameter of the coating section is 2-4mm, the diameter of the middle fixed section is 4.5-6.5mm, the diameter of the thick fixed section is 6-8mm, and the diameter of the clamping section is 3-6mm, and the transitions between the sections are chamfered at 45°.

[0026] The process of electric spark coating repair in step S3 is: the rotating speed of the electric spark rod is 1000-2500r / min, the power is 500W-1300W, the voltage is 60V-80V, the frequency is 280-500HZ, and the argon flow of the electric spark coating equipment is 5-8L / min.

[0027] The argon gas pipe provides argon gas for no less than 20s before the electric spark coating, and argon gas is continuously provided in the argon gas pipe during the electric spark coating process.

[0028] The argon gas flow in the argon gas pipe after forming the argon gas protection environment in the step S3 is 4-6L / min.

[0029] The welding current parameter of the step S4 remelting is 5-15A, and the welding time parameter is 70-90ms.

[0030] The heat treatment temperature of the step S5 is 280-300℃, and the holding time is 3-4h.

[0031] The beneficial effects of the present application are as follows:

[0032] 1. The electrode rod is prepared by turning after heat treatment of the QBe2 beryllium bronze bar, the strength of the electrode rod material is improved, the plastic deformation of the electrode rod caused by the centrifugal force generated by the high-speed rotation of the electrode rod in the electric spark coating repair process is avoided, and the shaking of the electrode rod caused by the high-speed rotation of the electrode rod in the electric spark coating repair process is reduced; in addition, the electrode rod is designed as a variable cross-section diameter cylinder, especially the diameters of the coating section, the medium diameter fixed section and the thick diameter fixed section are increased in turn, which will increase the structural stability of the long electrode rod in the high-speed rotation in the electric spark coating repair process, and reduce the shaking of the electrode rod; the diameter of the coating section is the smallest, which will reduce the contact area between the electrode rod and the damaged area in the electric spark coating repair process, so as to facilitate accurate repair of the damaged area.

[0033] 2. The argon gas pipe provides argon gas to the inner cavity of the beryllium bronze piston part through the small hole at the bottom of the beryllium bronze piston part to form an inert gas protection environment before the electric spark coating repair, and argon gas is continuously provided in the argon gas pipe during the electric spark coating process, so as to reduce the oxidation of the copper alloy in the electric spark coating process; the electric spark coating repair can preform a repair layer which is closely combined with the part substrate

[0034] 3. The cold welding machine has small heat input in the remelting process, which will not cause macroscopic deformation of the beryllium bronze piston part, and the remelting process occurs solid phase-liquid phase-solid phase transition, which can eliminate the cracks and un-melted defects formed in the electric spark coating repair process, reduce the pore defects, and form metallurgical bonding between the repair layer and the part substrate;

[0035] 4. The vacuum heat treatment can avoid the oxidation of the surface of the beryllium bronze piston part, the microstructure and properties of the beryllium bronze piston part substrate will not change at the heat treatment temperature, and the hardness of the material in the repair area can be improved;

[0036] 5. The method of electric spark coating repair + cold welding composite repair solves the problems of non-dense electric spark coating repair layer and difficult wire feeding in the cold welding inner hole repair process.

[0037] 6. The repair effect is verified by using test pieces, thus avoiding damage to the repaired parts. Attached Figure Description

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

[0039] Fig. 1 This is a schematic diagram of the damaged beryllium bronze piston part according to the present invention.

[0040] Fig. 2 This is a schematic diagram of the electrode rod structure of the present invention;

[0041] Fig. 3 This is a schematic diagram of the structure of the electrospark coating repair method of the present invention;

[0042] Fig. 4 This is a schematic diagram of the cold welding machine remelting according to the present invention;

[0043] Reference numerals: 1. Beryllium bronze piston part; 2. Damaged area; 3. Small hole; 4. Electrode rod; 5. Coating section; 6. Medium diameter fixed section; 7. Large diameter fixed section; 8. Clamping section; 9. Argon gas tube; 10. Electric spark welding torch; 11. Cold welding torch. Detailed Implementation

[0044] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below.

[0045] like Figs. 1 to 4 As shown, a method for repairing damage to the inner wall of a beryllium bronze piston part includes the following specific steps:

[0046] S1. Defect Inspection:

[0047] Visual inspection of beryllium bronze piston part 1 revealed the damaged area 2, and a small hole 3 at the bottom of beryllium bronze piston part 1.

[0048] S2, Electrode rod preparation;

[0049] Hot-rolled QBe2 beryllium bronze rods are heat-treated, and the heat-treated rods are then machined to prepare electrode rods 4. Electrode rods 4 consist of a coating section 5, a medium diameter fixing section 6, a rough diameter fixing section 7, and a clamping section 8.

[0050] Heat treatment of QBe2 beryllium bronze rods will increase the strength of the prepared electrode rods, avoid the centrifugal force generated by the high-speed rotation of the electrode rods during the electro-spark coating repair process, and reduce the vibration of the electrode rods caused by the high-speed rotation of the electrode rods during the electro-spark coating repair process.

[0051] The electrode rod with variable cross-section diameter, especially the diameters of the coating section 5, the middle diameter fixed section 6 and the thick diameter fixed section 7 are increased in turn, which can increase the structural stability of the electrode rod during high-speed rotation in the electric spark coating repair process and reduce the shaking of the electrode rod.

[0052] The diameter of the coating section 5 is set to be the smallest, which can reduce the contact area between the electrode rod and the damaged area during the electric spark coating repair process, so as to facilitate accurate repair of the damaged area.

[0053] S3, electric spark coating repair:

[0054] The argon gas pipe 9 is circumscribed at the position of the small hole 3, argon gas is transported by the argon gas pipe 9, the argon gas enters the inner cavity of the beryllium bronze piston part 1 from the small hole 3, and an argon gas protection environment is formed, the argon gas pipe 9 provides argon gas for 30s before electric spark coating, and argon gas is continuously provided in the argon gas pipe 9 during the electric spark coating process, the argon gas flow in the argon gas pipe 9 is 6L / min, the clamping section 8 of the prepared electrode rod is clamped on the welding gun 10 of the electric spark surfacing machine, and the electric spark surfacing machine is used to perform electric spark coating repair on the damaged part 2 of the inner hole.

[0055] The wall thickness of the repaired part is measured by the outer groove vernier caliper, and the measured wall thickness of the repaired part is greater than the thickness of the part by 110μm, and the electric spark coating repair is stopped.

[0056] Before the electric spark coating repair, argon gas is provided to the inner cavity through the small hole at the bottom of the beryllium bronze piston part through the argon gas pipe to form an inert gas protection environment, and argon gas is continuously provided in the argon gas pipe during the electric spark coating process, which can better provide inert gas protection during the repair process and reduce the oxidation of the copper alloy during the repair process. The electric spark coating repair can preform a repair layer that is tightly combined with the part substrate.

[0057] S4, cold welding machine remelting:

[0058] The cold welding machine device is used, the cold welding machine welding gun 11 is inserted into the inner wall damaged part 2 repaired by electric spark coating, the damaged part 2 is remelted, and a dense repair layer is obtained.

[0059] The cold welding machine remelting has small heat input and will not cause macroscopic deformation of the beryllium bronze piston part, and the remelting process undergoes solid phase→liquid phase→solid phase transition, which can eliminate the cracks and un-melted defects formed during the electric spark coating repair process, reduce the pore defects, and form a metallurgical bond between the repair layer and the part substrate.

[0060] S5, heat treatment:

[0061] The part treated by step S4 is put into a vacuum heat treatment furnace for heat treatment, vacuumized to below 1 Pa, then filled with argon to 0.1 MPa, the heat treatment temperature is 300℃, the holding time is 3h, the furnace is cooled to room temperature, then taken out, the vacuum heat treatment can avoid the oxidation of the surface of the beryllium bronze piston part, the hardness of the beryllium bronze piston part substrate will not change at this heat treatment temperature, and the hardness of the repaired area material can be improved;

[0062] S6, internal hole honing:

[0063] The internal hole is honed to remove the protruding part of the internal wall repair position, and meet the size use requirement;

[0064] S7, repair verification:

[0065] The same material and the same heat treatment state of the beryllium bronze piston part are used for the plate material, the plate material is QBe2, the heat treatment system is 780℃ for 2h water cooling, then 320℃ for 3h air cooling. After the same process treatment of step 3 electric spark coating and step 4 cold welding remelting, the metallography and hardness of the repaired part are detected. The metallography does not see cracks and un-melted defects, and the observation of the repaired layer and the plate substrate is metallurgical bonding. The hardness of the repaired layer and the plate substrate is detected, the hardness of the repaired layer is 361HV, 365HV, 367HV, 372HV, 368HV, the hardness of the substrate is 380HV, 384HV, 387HV, 385HV, 384HV, the average hardness of the repaired layer reaches 95.9% of the average hardness of the plate substrate, and it is determined that the beryllium bronze piston part repaired by step 1- step 6 is qualified. The heat treatment process of step S2 is: 780℃ for 2h water cooling, then 320℃ for 3h air cooling.

[0066] The electrode rod 4 of step S2 is a rotary body, wherein the diameter of the coating section 5 is 3mm, the diameter of the middle diameter fixed section 6 is 5mm, the diameter of the thick diameter fixed section 7 is 7mm, and the diameter of the clamping section 8 is 5mm, and the transition between each section is a 45° chamfer.

[0067] The process of electric spark coating repair of step S3 is that the rotating speed of the electric spark rod is 1500r / min, the power is 950W, the voltage is 70V, the frequency is 400HZ, and the argon flow of the electric spark coating equipment is 7L / min.

[0068] During the electric spark coating process, argon is continuously provided in the argon pipe 9, which can better provide inert gas protection for the repair process and reduce the oxidation of the copper alloy during the repair process. The electric spark coating repair can preform a repaired layer which is closely combined with the part substrate.

[0069] The welding current parameter of the step S4 remelting is 10 A, the welding time parameter is 80 ms, the cold welding machine remelting heat input is small, and the macroscopic deformation of the beryllium bronze piston part is not caused, and the remelting process occurs the transition of solid phase to liquid phase to solid phase, the crack and the unmelted defect formed in the electric spark coating repair process can be eliminated, the pore defect is reduced, and the repaired layer and the part substrate form the metallurgical combination.

[0070] The basic principles, main features and advantages of the present application are shown and described above. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A method of repairing an internal wall damage of a beryllium bronze piston part, characterized in that: The specific steps are as follows: S1, defect inspection: Visual inspection is performed on the beryllium bronze piston part (1), and the damaged part (2) is found. There is a small hole (3) at the bottom of the beryllium bronze piston part (1); S2, electrode rod preparation; The hot-rolled QBe2 beryllium bronze bar is heat treated, and the heat treated bar is machined to prepare an electrode rod (4). The composition of the electrode rod (4) includes a coating section (5), a middle diameter fixed section (6), a coarse diameter fixed section (7), and a clamping section (8); S3, electric spark coating repair: An argon tube (9) is connected to the position of the small hole (3), and argon is delivered by the argon tube (9). The argon enters the inner cavity of the beryllium bronze piston part (1) through the small hole (3), forming an argon protection environment. The clamping section (8) of the prepared electrode rod is clamped on the electric spark surfacing machine welding gun (10), and the electric spark surfacing machine is used to perform electric spark coating repair on the inner hole damaged part (2). An outside groove vernier caliper is used to measure the wall thickness of the repaired part. When the wall thickness of the repaired part is greater than 100 μm of the part thickness, the electric spark coating repair is stopped; S4, cold welding machine remelting: A cold welding machine is used, and the cold welding machine welding gun (11) is inserted into the inner wall damaged part (2) repaired by electric spark coating, and the damaged part (2) is remelted to obtain a dense repair layer; S5, heat treatment: The part treated in step S4 is placed in a vacuum heat treatment furnace for heat treatment. After vacuumizing to below 1 pa, argon is filled to 0.1 MPa for heat treatment. After the furnace is cooled to room temperature, it is taken out; S6, inner hole honing: The inner hole is honed to remove the protruding part of the inner wall repair position; S7, repair verification: The same material and the same heat treatment state of the beryllium bronze piston part are used to detect the metallography and hardness of the repaired part after steps S3 and S4: a. If no cracks and unmelted defects are found in the metallography, the observation of the repair layer and the substrate of the plate is metallurgical bonding, and the hardness of the repair layer and the substrate of the plate is detected; b. If the hardness of the repair layer reaches 90% of the substrate of the plate, the beryllium bronze piston part repaired by steps 1-6 is determined to be qualified; The heat treatment process of step S2 is 770-790℃ for 1-2h water cooling, followed by 310-320℃ for 2-4h air cooling. The process of electric spark coating repair in step S3 is that the rotating speed of the electric spark rod is 1000-2500 r / min, the power is 500-1300 W, the voltage is 60-80 V, the frequency is 280-500 HZ, and the argon flow of the electric spark coating equipment is 5-8 L / min. After the argon protection environment is formed in step S3, the argon flow in the argon tube (9) is 4-6 L / min. The welding current parameter for remelting in step S4 is 5-15 A, and the welding time parameter is 70-90 ms. The heat treatment temperature in step S5 is 280-300℃, and the holding time is 3-4h.

2. The method of claim 1, wherein: The electrode stick (4) of step S2 is a rotary body, wherein the diameter of the coating section (5) is 2-4 mm, the diameter of the middle fixed section (6) is 4.5-6.5 mm, the diameter of the thick fixed section (7) is 6-8 mm, and the diameter of the clamping section (8) is 3-6 mm, and the transition between each section is a 45° chamfer.

3. The method of claim 1, wherein: The argon tube (9) provides argon for no less than 20 s before the electric spark coating, and argon is continuously provided in the argon tube (9) during the electric spark coating.

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