Method for repairing local welding surface of multi-welding-seam copper steel diffusion welding structure part

Abstract

The invention belongs to the technical field of welding, and relates to a method for repairing a local welding surface of a multi-welding-seam copper steel diffusion welding structure part. The method comprises the following steps: firstly, repairing a welding surface of a plunger hole, and putting a rotor assembly and a copper sleeve part which need to be repaired and corresponding tools into a diffusion welding furnace for diffusion welding; and the diffusion welding surface is inspected through a water immersion C-type ultrasonic detection method. Afterwards, the inner positioning tool and the outer positioning tool are removed from the copper pad part for repairing the welding surface of the bottom copper pad in a milling mode and the like, and the copper pad is machined until the size of the part is recovered, so that the size of the part meets the drawing requirement. The welding surface with welding defects in the rotor assembly can be effectively repaired through the method, and the welding quality of the rotor assembly is improved. And the repair process does not cause the failure of the other welding surfaces subjected to diffusion welding. The welding surfaces with welding defects in the rotor assembly type parts can be repaired, and the rejection rate of the rotor assembly type parts in the welding process is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of welding and relates to a method for repairing a local welding surface of a multi-weld copper-steel diffusion-welded structural part. Background Art

[0002] The core component that controls the product flow in the fuel plunger pump is the rotor assembly. Generally, in order to improve the wear resistance of the working friction pair, the inner wall and bottom surface of the plunger hole of the rotor assembly are mostly made of leaded bronze alloy. In aviation products, the rotor assembly is mostly manufactured using the copper / steel dissimilar metal diffusion welding process.

[0003] At present, rotor assemblies produced by various process methods have a high scrap rate in the welding process. The reason is that the rotor assembly has a complex structure, with 9 vertical cylindrical deep blind hole structure welding surfaces and 1 circular welding plane, and the total diffusion welding area is large; it is necessary to complete the diffusion welding of 10 welding surfaces simultaneously in one welding process. If any welding surface has a non-welding defect, the entire part will be scrapped.

[0004] Therefore, there is an urgent need for a repair technology that can repair the local welding surface of copper / steel diffusion welded structural parts to reduce production losses caused by defective products. Summary of the invention

[0005] The purpose of the present invention is to solve the above technical problems and to provide a method for repairing the local welding surface in a multi-weld copper-steel diffusion-welded structural part.

[0006] The technical solution of the present invention:

[0007] A method for repairing a local welding surface of a multi-weld copper-steel diffusion-welded structural part comprises the following steps:

[0008] (1) Before repair, the copper sleeve with welding defects in the cylindrical hole is completely removed by machining;

[0009] (2) According to the diameter D of the cylindrical hole of the rotor body after the copper sleeve is removed, the corresponding copper sleeve is processed;

[0010] (3) Place the protective tooling into the copper sleeve hole that does not need to be repaired by welding, place the newly processed copper sleeve into the matching cylindrical hole of the rotor body to be repaired, and then place the pressurizing tooling into the copper sleeve; finally, place the assembled parts to be welded into the diffusion welding furnace for repair diffusion welding;

[0011] (4) According to the number of cylindrical holes to be repaired N, adjust the total welding load F to be applied; that is:

[0012] Total welding load F n =Number of cylindrical holes to be repaired N×Load required for a single cylindrical hole F 1

[0013] (5) After welding is completed, the protective tooling and pressurizing tooling are removed by boring and milling, and the copper sleeve in the welding surface of the repaired cylindrical hole is processed to restore the part size to meet the drawing requirements;

[0014] (6) The diffusion welding surface shall be inspected by water immersion C-type ultrasonic testing method, and there shall be no unwelded defects.

[0015] Furthermore, the diameter d of the special copper sleeve for repairing the cylindrical hole of the rotor assembly is smaller than the diameter D of the cylindrical hole of the rotor body after the original copper sleeve is removed through machining, and the difference is no greater than 0.02 mm.

[0016] Furthermore, the roughness requirements of the inner surface of the cylindrical hole of the rotor body to be repaired and the outer surface of the copper sleeve are not less than Ra0.8μm.

[0017] Furthermore, the difference between the outer diameter of the protective tooling and the inner diameter of the copper sleeve is not greater than 0.02 mm, and the protective tooling is made of the same material as the copper sleeve or has a thermal expansion coefficient of ≥20×10 -6 / K -1 processed from materials.

[0018] Furthermore, the pressurizing tooling in the cylindrical hole to be repaired of the rotor assembly adopts a tapered cylindrical pin structure, and the taper is no greater than 5°.

[0019] Furthermore, the load F on the weld surface of the cylindrical hole of a single rotor assembly is repaired. 1 Choose from 1100N-8900N range depending on part size.

[0020] Furthermore, the temperature range of diffusion welding of the rotor assembly is 780°C-900°C.

[0021] Furthermore, when repairing the diffusion welding surface of the copper pad on the bottom of the rotor assembly, the original bottom copper pad is first removed, and then the protective tooling is placed in all the cylindrical holes of the rotor body, and the newly made copper pad parts to be welded are assembled with the rotor assembly and the special tooling for diffusion welding. The total welding load F n =9×the load F required for a single cylindrical hole 1 .

[0022] Furthermore, the surface of the copper sleeve parts is flash-plated with nickel before welding.

[0023] The beneficial effects of the present invention are:

[0024] The method can effectively repair the welding surface with welding defects in the rotor assembly, and the repair process will not cause failure of other welding surfaces that have completed diffusion welding.

[0025] By adopting the method, the welding surface with welding defects in the rotor assembly parts can be repaired, and the scrap rate of the rotor assembly parts in the welding process can be effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the typical parts rotor assembly structure, where a is a cross-sectional view of the rotor assembly, and b is a top view of the rotor assembly; 1 is the rotor body, 2 is the copper sleeve, and 3 is the copper pad.

[0027] Figure 2 Schematic diagram of the pressurized tooling used to repair the diffusion welding surface of the cylindrical hole structure of the rotor assembly.

[0028] Figure 3 Tooling for repairing the diffusion welding surface of the plane structure at the bottom of the rotor assembly. 4 is the copper pad part to be welded, 5 is the inner positioning tooling, and 6 is the outer positioning tooling. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings.

[0030] A method for repairing a local welding surface of a multi-weld copper-steel diffusion-welded structural part comprises the following steps:

[0031] a. Repair of plunger hole welding surface

[0032] Step 1: Before repair, the copper sleeve 2 with welding defects in the cylindrical hole of the rotor assembly is removed by machining until the steel matrix is ​​completely exposed; the surface roughness requirement is not less than Ra0.8μm.

[0033] Step 2: Process the copper sleeve parts to be welded according to the diameter D of the cylindrical hole of the rotor body 1 after removing the copper sleeve 2.

[0034] 1) The diameter d of the special copper sleeve for repairing the cylindrical hole of the rotor assembly should be smaller than the diameter D of the cylindrical hole of the rotor body after machining, and the difference should not be greater than 0.02mm; the outer surface roughness of the copper sleeve should not be less than Ra0.8μm.

[0035] 2) The inner hole of the copper sleeve for the cylindrical hole to be repaired is a conical structure, and the outer circle of the pressurizing tooling is also a conical structure; the two cooperate through the conical structure to realize the conversion of vertical load into radial horizontal load; the angle of the cone is equal and not greater than 5°. Figure 2 shown.

[0036] 3) The surface of the copper sleeve parts is flash nickel plated before welding.

[0037] Step 3: After thoroughly cleaning and removing the oil stains from the rotor assembly and copper sleeve parts to be repaired and the corresponding tooling, assemble them and place them in a diffusion welding furnace for diffusion welding.

[0038] 1) Put a protective tooling in the cylindrical hole of the rotor assembly that does not need to be repaired to avoid repeated heating to damage the qualified welding surface; the difference between the outer diameter of the protective tooling and the inner diameter of the copper sleeve is not greater than 0.02mm, and the protective tooling is made of the same material as the copper sleeve or has a thermal expansion coefficient of ≥20×10 -6 / K -1 processed from materials.

[0039] 2) Diffusion welding temperature range is 780℃-900℃.

[0040] 3) The load applied by diffusion welding is determined by the number of cylindrical holes to be repaired. The total welding load (F n ) = Number of cylindrical holes to be repaired (N) × Load required for a single cylindrical hole (F 1 ). The load required for a single cylindrical hole (F 1 ) range is 1100N-8900N.

[0041] Step 4: Remove the protective tooling and the pressurizing tooling by boring, milling, etc., and process the copper sleeve 1 to restore the part size to meet the requirements of the drawing;

[0042] Step 5: Check the diffusion welding surface by water immersion C-type ultrasonic testing method, and there should be no unwelded defects.

[0043] b. Repair of the bottom copper pad welding surface

[0044] Step 1: Remove the bottom copper pad 3 of the rotor assembly with welding defects by machining until the steel matrix is ​​completely exposed; the surface roughness requirement is not less than Ra0.8μm.

[0045] Step 2: Process the copper pad part 4 for repair and the special inner positioning tool 5 and the outer limiting tool 6.

[0046] 1) The thickness of the special inner positioning fixture 5 and the outer limit fixture 6 should be consistent, and the surface roughness requirement is Ra3.2μm.

[0047] 2) The repair copper pad part 4 is clearance-matched with the inner positioning fixture 5 and the outer limiting fixture 6, and the single-side clearance is controlled to be no greater than 0.05 mm.

[0048] 3) The surface of the copper pad parts is flash nickel plated before welding.

[0049] Step 3: After thoroughly cleaning and removing the oil stains from the rotor assembly, copper pad parts and corresponding tooling to be repaired, assemble them and place them in a diffusion welding furnace for diffusion welding.

[0050] 1) Put a protective tooling in the cylindrical hole of the rotor assembly that does not need to be repaired to avoid repeated heating to damage the qualified welding surface; the difference between the outer diameter of the protective tooling and the inner diameter of the copper sleeve is not greater than 0.02mm, and the protective tooling is made of the same material as the copper sleeve or has a thermal expansion coefficient of ≥20×10 -6 / K -1 processed from materials.

[0051] 2) Diffusion welding temperature range is 780℃-900℃.

[0052] 3) The load applied by diffusion welding is determined by the number of cylindrical holes to be repaired. The total welding load (F n )=9×Required load for a single cylindrical hole (F 1 ). The load required for a single cylindrical hole (F 1 ) range is 1100N-8900N.

[0053] Step 4: Use milling or other methods to remove the internal and external positioning tools, and process the copper pad 4 to restore the part size to meet the drawing requirements;

[0054] Step 5: Check the diffusion welding surface by water immersion C-type ultrasonic testing method, and there should be no unwelded defects.

Claims

1. A method for repairing local welding surfaces of multi-weld copper-steel diffusion-welded structural parts, characterized in that: The following steps are involved: (1) Before repair, the copper sleeve with welding defects in the cylindrical hole is completely removed by machining; (2) According to the diameter D of the cylindrical hole of the rotor body after the copper sleeve is removed, the corresponding copper sleeve is processed; (3) Place the protective tooling into the copper sleeve hole that does not need to be repaired by welding, place the newly processed copper sleeve into the matching cylindrical hole of the rotor body to be repaired, and then place the pressurizing tooling into the copper sleeve; finally, place the assembled parts to be welded into the diffusion welding furnace for repair diffusion welding; (4) According to the number N of cylindrical holes to be repaired, adjust the total welding load F to be applied; Right now: Total welding load F n =Number of cylindrical holes to be repaired N×Load required for a single cylindrical hole F1 (5) After welding is completed, the protective tooling and pressurizing tooling are removed by boring and milling, and the copper sleeve in the welding surface of the repaired cylindrical hole is processed to restore the part size to meet the drawing requirements; (6) The diffusion welding surface shall be inspected by water immersion C-type ultrasonic testing method, and there shall be no unwelded defects.

2. The method for repairing local welding surfaces of multi-weld copper-steel diffusion-welded structural parts according to claim 1 is characterized in that: The diameter d of the special copper sleeve for repairing the cylindrical hole of the rotor assembly is smaller than the diameter D of the cylindrical hole of the rotor body after the original copper sleeve is removed through processing, and the difference is no more than 0.02 mm.

3. The method for repairing local welding surfaces of multi-weld copper-steel diffusion-welded structural parts according to claim 1 is characterized in that: The roughness requirements for the inner surface of the cylindrical hole of the rotor body to be repaired and the outer surface of the copper sleeve are no less than Ra0.8μm.

4. The method for repairing local welding surfaces of multi-weld copper-steel diffusion-welded structural parts according to claim 1 is characterized in that: The difference between the outer diameter of the protective tooling and the inner diameter of the copper sleeve is not greater than 0.02mm. The protective tooling is made of the same material as the copper sleeve or the thermal expansion coefficient is ≥20×10 -6 / K -1 processed from materials.

5. The method for repairing local welding surfaces of multi-weld copper-steel diffusion-welded structural parts according to claim 1 is characterized in that: The pressurized tooling in the cylindrical hole of the rotor assembly to be repaired adopts a tapered cylindrical pin structure with a taper not exceeding 5°.

6. The method for repairing local welding surfaces of multi-weld copper-steel diffusion-welded structural parts according to claim 1 is characterized in that: The load F1 for repairing the cylindrical hole welding surface of a single rotor component is selected in the range of 1100N-8900N according to the part size.

7. The method for repairing local welding surfaces of multi-weld copper-steel diffusion-welded structural parts according to claim 1 is characterized in that: The temperature range for diffusion welding of rotor components is 780℃-900℃.

8. The method for repairing local welding surfaces of multi-weld copper-steel diffusion-welded structural parts according to claim 1 is characterized in that: When repairing the diffusion welding surface of the copper pad on the bottom of the rotor assembly, first remove the original bottom copper pad, then put the protective tooling into all the cylindrical holes of the rotor body, assemble the newly made copper pad parts to be welded with the rotor assembly and the special tooling, and then perform diffusion welding. The total welding load F n =9×the load F1 required for a single cylindrical hole.

9. The method for repairing local welding surfaces of multi-weld copper-steel diffusion-welded structural parts according to claim 1, characterized in that: The surface of the copper sleeve parts is flash nickel plated before welding.

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