Spot welding repair method for depth defect of metal part

Abstract

The invention provides a spot welding repair method for a deep defect of a metal part, which comprises the following steps of: 1, processing a conical hole or a conical groove according to the size of the defect so as to remove the defect; 2, a matched filling material is prepared according to the machined conical hole or conical groove; 3, filling materials are installed in the conical holes or the conical grooves in an interference fit mode; 4, welding parameters are set, and resistance spot welding is conducted; and 5, after welding, polishing and shaping are conducted, so that the molded surface after welding meets the repair requirement. By the adoption of the repairing method, welding heat input is small, the problem that the part is deformed after being welded due to the fact that thermal stress is too large is solved, welding quality is improved, welding materials such as protective gas, welding flux and welding wires are not needed, and repairing cost is low.

Description

Technical Field

[0001] The invention belongs to the technical field of metal parts defect repair, and in particular relates to a spot welding repair method for deep defects of metal parts. Background Art

[0002] During long-term use or service, metal parts are easily affected by collision, corrosion or vibration, which may lead to the formation of three-dimensional pit defects and thickness crack defects. These defects present two forms of damage: penetrating and non-penetrating. For shallow pit defects, arc surfacing, laser cladding and other methods are usually used for repair. However, for pit defects with a relatively large depth and diameter, conventional arc surfacing and laser cladding may cause the welding position to be not reached, resulting in the formation of incomplete cavities and pores inside the repaired parts. If large-area excavation and welding are used, although the welding position can be reached, the large welding area may easily lead to the expansion of the heat-affected zone of the repaired area after welding, which greatly reduces the performance of the repaired parts.

[0003] In addition, for the extension cracks in the thickness direction, the method of repairing by surfacing welding after defect digging is often used, such as the Chinese invention patent CN109483149A, but this repair method has the following defects: insufficient welding wire filling will cause new porosity defects, and the large heat-affected zone of repair will cause deformation of parts, thermal stress concentration, and degradation of part material performance. If brazing repair with a small heat input is used, although the three-dimensional defects can be filled by filling with brazing filler, the selection of brazing filler cannot be consistent with the raw materials, because the welding principle of brazing requires that the brazing filler melts while the parent material cannot melt, so the melting point of the brazing filler must be lower than that of the parent material; secondly, brazing takes a long time, the process is complex, the operation is difficult, the production efficiency is low, it is not easy to realize automated production, and it is more dependent on the selection of brazing filler and brazing agent. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing repair methods for deep defects such as pit-type and deep cracks on metal parts, such as complex processes, excessive thermal stress and reduced material performance of parts after repair, and to propose a spot welding repair method for deep defects of metal parts. The method of the present invention first processes a tapered hole or a tapered groove according to the size of the deep defect, then prepares a filling material according to the size of the tapered hole or the tapered groove, and finally welds the filling material into the tapered hole or the tapered groove by resistance spot welding to complete the repair of the deep defects of the metal parts, effectively avoiding the problem of part deformation caused by excessive thermal stress, and having high repair quality and repair efficiency.

[0005] To achieve the above purpose, the technical solution provided by the present invention is:

[0006] A spot welding repair method for deep defects of metal parts comprises the following steps:

[0007] Step 1, determining the defect area to be repaired of the metal part, and processing the defect area to be repaired to form a tapered hole or tapered groove with a large upper end and a small lower end according to the size of the defect to be repaired, and ensuring that the defect is completely removed after processing;

[0008] Step 2: Clean and dry the defective area to be repaired;

[0009] Step 3, preparing a filling material according to the shape and size of the tapered hole or tapered groove processed in step 1; the filling material is used for interference fit with the tapered hole or the tapered groove;

[0010] Step 4, installing the prepared filling material in the tapered hole or tapered groove so that the small end surface of the filling material fits with the small end surface of the tapered hole or the tapered groove;

[0011] Step 5, selecting an upper electrode head and a lower electrode head of a resistance spot welding machine, setting welding parameters, and welding the filling material into the tapered hole or the tapered groove;

[0012] Step 6: Grind and reshape the defective area to be repaired after welding.

[0013] Furthermore, in step 1, if the defect is a penetrating defect, a conical hole with a large upper end and a small lower end is formed in the defect area to be repaired according to the size of the defect to be repaired; if the defect is a non-penetrating defect, a conical groove with a large upper end and a small lower end is formed in the defect area to be repaired according to the size of the defect to be repaired.

[0014] Furthermore, in step 1, the diameter of the upper end of the tapered hole or the tapered groove is 1-10 mm larger than the diameter of the lower end.

[0015] Furthermore, in step 2, the defective area to be repaired is cleaned with alcohol and then blown dry.

[0016] Furthermore, in step 3, the height of the prepared filling material is 1-5 mm higher than the height of the tapered groove or the tapered hole.

[0017] Furthermore, in step 5, the upper electrode head and the lower electrode head of the resistance spot welding machine are cylindrical, and the diameter is 2-8 mm larger than the diameter of the large end of the filling material.

[0018] Furthermore, in step 5, the welding parameters set are: welding current 5kA-10kA, welding time 0.2s-0.5s, electrode pressure 5kN-10kN, welding speed 0.5cm / s-0.9cm / s, and holding time 0.2s-0.5s.

[0019] The advantages of the present invention are:

[0020] 1. The method of the present invention first processes a tapered hole or tapered groove according to the depth and width of the defect of the metal part, and then welds the filling material prepared according to the size of the tapered hole or tapered groove into the processed tapered hole or tapered groove by the resistance spot welding method according to the set welding parameters, so as to repair deep defects such as pit-type or deep cracks. Compared with conventional fusion welding repair methods such as argon arc welding, a lot of repair time is saved, the welding repair efficiency is improved, and the welding heat input is much smaller than that of conventional fusion welding, which avoids the problem of deformation of parts after welding due to excessive thermal stress, and also effectively avoids the situation of element burning of the material in the repair area due to overheating.

[0021] 2. The grooves or holes processed at the defective parts and the prepared filling materials in the method of the present invention are all designed with a conical structure. Since there is an angle between the outer wall of the conical structure and the axial direction of the upper and lower electrodes of the resistance spot welding machine, it can produce a good extrusion effect compared with other structural forms. When the upper and lower electrodes of the resistance spot welding machine are working, the outer wall of the filling material fits well with the inner wall of the groove or hole under the extrusion effect, ensuring that the contact surface of the groove or hole and the filling material is better affected by the welding heat to form a metallurgical bonding area; at the same time, the design of the conical structure facilitates the positioning and installation of the filling material.

[0022] 3. In the method of the present invention, the filling material can be selected from the parent metal or dissimilar metal. When the filling material is made of the same material as the part matrix, the consistency of the performance of the repaired area and the part raw material is guaranteed after repair, the repair quality is improved, and a wide range of metal materials can be repaired.

[0023] 4. The method of the present invention is easy to operate, does not require welding materials such as protective gas, flux, welding wire, etc. during repair, has low repair cost and high repair efficiency, and can realize automated repair production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0025] Figure 1 It is a flowchart of the spot welding repair method for deep defects of metal parts of the present invention;

[0026] Figure 2 is a schematic diagram of a tapered hole or tapered groove processed for defect elimination in the method of the present invention;

[0027] Figure 3 is a schematic diagram of the structure of the filling material prepared in the method of the present invention;

[0028] Figure 4 It is a schematic diagram of the matching between the filling material and the tapered hole or tapered groove processed in the area to be repaired;

[0029] Figure 5 Schematic diagram of resistance spot welding in the method of the present invention, wherein the arrow in the figure indicates the movement direction of the electrode head on the resistance spot welding machine;

[0030] Figure 6 It is a schematic diagram of a metal part after the profile surface is ground in the method of the present invention.

[0031] Explanation of the reference numerals: 1 - metal part, 2 - conical structure, 3 - filling material, 4 - upper electrode head, 5 - lower electrode head. DETAILED DESCRIPTION

[0032] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0033] Reference Figure 1 In order to repair pit defects and deep crack defects on metal parts, the present invention provides a spot welding repair method for deep defects of metal parts, comprising the following steps:

[0034] Step 1, defect removal: According to the defect size, a milling machine is used to perform milling processing on the area to be repaired of the metal part 1 to form a regular conical structure 2 with a large upper end and a small lower end. The conical structure 2 is a conical hole or a conical groove. After processing, the defect is ensured to be completely removed to reveal the metallic luster. The upper end diameter of the conical hole or conical groove is 1-10 mm larger than the lower end diameter, and the surface roughness is ≤Ra1.6μm.

[0035] Step 2: Clean the defective area to be repaired with alcohol and blow dry it.

[0036] Step 3, prepare a filling material 3 according to the shape and size of the tapered hole or tapered groove; the height of the prepared filling material is 1-5 mm greater than the height of the processed tapered hole or tapered groove, and the outer diameter of the filling material is slightly greater than the inner diameter of the tapered hole or tapered groove, ensuring that the filling material can be interference-fitted with the tapered hole or tapered groove. The surface roughness of the filling material is ≤Ra1.6μm.

[0037] Step 4, installing the prepared filling material in the tapered hole or tapered groove, and after installation, the small end surface of the filling material is fitted with the small end surface of the tapered groove or tapered hole.

[0038] Step 5, first: select the upper electrode head 4 and the lower electrode head 5 of the resistance spot welding machine. The upper electrode head 4 and the lower electrode head 5 are cylindrical and have flat end faces. The size of the lower electrode head is consistent with the size of the upper electrode head, and the diameter of the upper electrode head and the lower electrode head is 2-8 mm larger than the diameter of the large end of the filling material.

[0039] Then, set the welding parameters: welding current is 5kA-10kA, welding time is 0.2s-0.5s, electrode pressure is 5kN-10kN, welding speed is 0.5cm / s-0.9cm / s, and holding time is 0.2s-0.5s.

[0040] Finally, align the center of the upper electrode head 4 with the center of the large end of the filling material, and ensure that the plane of the area to be repaired is perpendicular to the up and down movement direction of the electrode, and start welding.

[0041] Step 6: After welding, the post-weld area is polished and reshaped according to the design until the surface size of the repaired area meets the repair requirements.

[0042] The following uses two specific embodiments as examples to illustrate the process of welding and repairing penetrating and non-penetrating depth defects using the method of the present invention.

[0043] Example 1: Taking the crack repair process of a 2A12 aluminum alloy component with a thickness of 10 mm and a depth of 5 mm and an extension path width of 3 mm as an example, the process specifically includes the following steps:

[0044] Step 1, such as Figure 2 As shown, defect removal processing: the milling machine is used to mill the crack defect part on the 10mm thick 2A12 aluminum alloy component, and the processing is a tapered groove with a large upper end and a small lower end. The processing depth is 5mm, the lower end circle diameter is about 3.5mm, and the upper end circle diameter is about 8.5mm. The defects must be completely removed during processing until the metal luster is processed, and the surface roughness is ≤Ra1.6μm.

[0045] Step 2, cleaning: Clean the processed area with alcohol to ensure that there is no excess material visible to the naked eye, and blow dry with a hair dryer.

[0046] Step 3, such as Figure 3 As shown, defect filling material 3 is prepared: according to the size of the tapered groove processed in step 1, filling material 3 is processed and prepared. Filling material 3 is made of 2A12 aluminum alloy, and is in the shape of a cone with a large upper end and a small lower end, with a height of 8mm, a lower end diameter of 3.7mm, and an upper end diameter of 8.8mm, and is processed to have a metallic luster, and the surface roughness is ≤Ra1.6μm.

[0047] Step 4, such as Figure 4 As shown, fill the filling material: vertically place the filling material 3 on the tapered groove processed in step 1, and use a hammer to evenly knock the filling material 3 into the tapered groove to ensure that the small end surface of the filling material is in contact with the bottom surface of the tapered groove, as shown in FIG. Figure 3 shown.

[0048] Step 5, such as Figure 5 As shown, resistance spot welding.

[0049] First: process the upper electrode head 4 of the resistance spot welder. The upper electrode head of the resistance spot welder adopts a cylindrical design and a flat end face. The end diameter of the upper electrode head 4 of the resistance spot welder is 11-13mm. The contact end face size of the lower electrode head 5 of the resistance spot welder is consistent with the size of the upper electrode head 4 of the resistance spot welder. Align the center position of the upper end face of the filling material 3 with the center position of the upper electrode head 4 of the resistance spot welder to ensure that the plane of the position to be repaired is perpendicular to the up and down movement direction of the electrode.

[0050] Then: set the welding parameters: welding current is 10kA, welding time is 0.5s, electrode pressure is 10kN; welding speed is 0.9cm / s, and holding time is 0.5s. Turn on the welding machine. After welding, under the pressure of the upper and lower electrodes and the welding heat input, the filling material will fill the conical groove. Since the height of the filling material is 8mm and the depth of the conical groove is 5mm, as long as the welding is carried out once according to the set welding parameters, the filling material can be completely filled into the conical groove to achieve defect repair.

[0051] Step 6, post-weld surface repair: Grind and reshape the repaired area after resistance spot welding to restore the surface size of the repaired part to the required size. Figure 6 shown.

[0052] After the repair is completed, the repair area is inspected for quality using non-destructive testing methods such as X-ray testing and fluorescence testing according to actual requirements. After testing, the repaired defective area is basically consistent with the original metal part material performance and meets the use requirements.

[0053] Example 2: Taking the repair of a through crack with a crack extension path width of 2 mm on a 5 mm thick GH4169 high temperature alloy component as an example, the invention specifically comprises the following steps:

[0054] Step 1, defect elimination processing: Use a milling machine to mill the through crack defect on the 5mm thick GH4169 high-temperature alloy component, and process it into a tapered hole with a large upper end and a small lower end, with a lower end circle diameter of 2.5mm and an upper end circle diameter of 5.5mm. During processing, defects must be completely eliminated until the metal luster is processed and the surface roughness is ≤Ra1.6μm.

[0055] Step 2, cleaning: Clean the processed area with alcohol to ensure that there is no excess material visible to the naked eye, and blow dry with a hair dryer.

[0056] Step 3, prepare defect filling material: according to the size of the tapered hole processed in step 1, prepare the filling material. The filling material is GH4169 high-temperature alloy material, which is in the shape of a cone with a large upper end and a small lower end, a height of 8m, a lower end diameter of 3mm, and an upper end diameter of 6mm. It is processed to have a metallic luster and a surface roughness of ≤Ra1.6μm.

[0057] Step 4, filling with filling material: Place the filling material vertically on the tapered hole processed in step 1, and use a hammer to knock the filling material evenly into the tapered hole until the small end of the filling material is flush with the small end of the tapered hole.

[0058] Step 5, resistance spot welding.

[0059] First, the upper electrode head 4 of the resistance spot welding machine is processed. The upper electrode head of the resistance spot welding machine adopts a cylindrical design and a flat end face. The end diameter of the upper electrode head 4 of the resistance spot welding machine is 8-12mm. The contact end face size of the lower electrode head 5 of the resistance spot welding machine is consistent with the size of the upper electrode head 4 of the resistance spot welding machine. Align the center position of the upper end face of the filling material with the center position of the upper electrode head 4 of the resistance spot welding machine, and ensure that the upper end face of the filling material is perpendicular to the up and down movement direction v1 of the electrode.

[0060] Then: start welding, the welding parameters are: welding current: 5kA-10kA; welding time: 0.2-0.5s; electrode pressure: 5kN-10kN; welding speed: 0.5-0.9cm / s; holding time: 0.2-0.5s. Perform welding operation according to the set welding parameters. Under the action of upper and lower electrode pressure and welding heat input, the filling material will fill the conical hole and form a metallurgical bonding area under the action of welding heat.

[0061] Step 6, surface processing: Grind and reshape the repaired area after resistance spot welding to restore the surface size of the repaired part to the size required for repair.

[0062] After the repair is completed, non-destructive testing is performed on the repaired area. After testing, the performance of the repaired defective area is basically consistent with the original metal part material, meeting the use requirements.

[0063] If there are other defects on the metal parts that have not been eliminated, they can be repaired according to steps 1 to 6. The repair quality is high and will not affect the performance of the metal parts.

[0064] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be included in the protection scope of the present invention.

Claims

1. A spot welding repair method for deep defects of metal parts, characterized in that: The following steps are involved: Step 1, determining the defect area to be repaired of the metal part, and processing the defect area to be repaired to form a tapered hole or tapered groove with a large upper end and a small lower end according to the size of the defect to be repaired, and ensuring that the defect is completely removed after processing; Step 2: Clean and dry the defective area to be repaired; Step 3, preparing a filling material according to the shape and size of the tapered hole or tapered groove processed in step 1; the filling material is used for interference fit with the tapered hole or the tapered groove; Step 4, installing the prepared filling material in the tapered hole or tapered groove so that the small end surface of the filling material fits with the small end surface of the tapered hole or the tapered groove; Step 5, selecting an upper electrode head and a lower electrode head of a resistance spot welding machine, setting welding parameters, and welding the filling material into the tapered hole or the tapered groove; Step 6: Grind and reshape the defective area to be repaired after welding.

2. The spot welding repair method according to claim 1, characterized in that: In step 1, if the defect is a penetrating defect, a conical hole with a large upper end and a small lower end is formed in the defect area to be repaired according to the size of the defect to be repaired; if the defect is a non-penetrating defect, a conical groove with a large upper end and a small lower end is formed in the defect area to be repaired according to the size of the defect to be repaired.

3. The spot welding repair method according to claim 2, characterized in that: In step 1, the diameter of the upper end of the tapered hole or the tapered groove is 1-10 mm larger than the diameter of the lower end.

4. The spot welding repair method according to claim 1, characterized in that: In the step 2, the defective area to be repaired is cleaned with alcohol, and then blown dry.

5. The spot welding repair method according to claim 1, characterized in that: In the step 3, the height of the prepared filling material is 1-5 mm higher than the height of the tapered groove or the tapered hole.

6. The spot welding repair method according to claim 5, characterized in that: In step 5, the upper electrode head and the lower electrode head of the resistance spot welding machine are cylindrical, and the diameter is 2-8 mm larger than the diameter of the large end of the filling material.

7. The spot welding repair method according to claim 6, characterized in that: In step 5, the welding parameters are set as follows: welding current 5kA-10kA, welding time 0.2s-0.5s, electrode pressure 5kN-10kN, welding speed 0.5cm / s-0.9cm / s, and holding time 0.2s-0.5s.

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