Thin-wall corrugated pipe welding method based on resistance seam welding

Abstract

The invention belongs to the technical field of welding, and particularly relates to a thin-wall corrugated pipe welding method based on resistance seam welding. Comprising the following steps: 1, mechanically polishing the inner and outer surfaces of a pipe orifice at the welding end of the corrugated pipe, the outer surface of a part and the inner surface of a welding ring, and then wiping with acetone and airing; secondly, the corrugated pipe, the part and a welding ring are tightly assembled, the welding ring is assembled on the outer side of the corrugated pipe, the part is assembled on the inner side of the corrugated pipe, and the end face of the welding ring is flush with the end face of the corrugated pipe; thirdly, the assembled assembly is subjected to evenly-distributed four-point positioned welding along the circumference in a resistance spot welding mode; fourthly, the middle of the welding ring is annularly welded through resistance seam welding, and a welding joint is formed; and fifthly, air tightness inspection is conducted on the welded joint.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a thin-walled corrugated pipe welding method based on resistance seam welding. Background Art

[0002] The bellows is a cylindrical thin-walled elastic tube with multiple transverse corrugations. It is an important component of the pipeline compensator to play the role of expansion and contraction compensation. In the aircraft pipeline system, it can compensate for the displacement of the pipeline caused by temperature changes, vibrations, installation errors and other factors, and avoid damage to the pipeline due to excessive deformation.

[0003] In the pipeline compensator, the straight edge section of the thin-walled bellows is welded to the end pipe or flange and other components to form a whole. The thickness of the bellows generally does not exceed 0.6mm, and the thickness ratio of the bellows is too different from that of the end of the part, so it is not suitable to be welded by fusion welding. Resistance seam welding uses the resistance heat of the current passing through the weldment and its contact to locally heat the weldment to a plastic or molten state, and then applies pressure to connect the weldment. It is suitable for thin-walled structure welding. Therefore, resistance seam welding is the main method of bellows welding.

[0004] However, the thickness ratio between the parts of the resistance seam welding of this type of product is generally not less than 5, and the thickness ratio between the welded parts is large. During the welding process, the thin-walled corrugated pipe is prone to over-burning, resulting in product scrapping. Summary of the invention

[0005] The purpose of the present invention is to provide a thin-walled bellows welding method based on resistance seam welding, so that the weld nugget deviation phenomenon can be corrected, the parts on both sides of the bellows form a qualified penetration rate, and the weld is beautifully formed.

[0006] The technical solution of the present invention:

[0007] A thin-walled corrugated pipe welding method based on resistance seam welding comprises the following steps:

[0008] The first step is to mechanically polish the inner and outer surfaces of the bellows welding end, the outer surface of the parts and the inner surface of the welding ring, and then wipe them clean with acetone and dry them;

[0009] The second step is to tightly assemble the bellows, parts and welding ring, wherein the welding ring is assembled on the outside of the bellows, the parts are assembled on the inside of the bellows, and the end face of the welding ring is flush with the end face of the bellows;

[0010] The third step is to evenly distribute four points of positioning welding along the circumference of the assembled components by resistance spot welding;

[0011] The fourth step is to perform annular welding on the middle part of the welding circle by using resistance seam welding to form a welding joint;

[0012] The fifth step is to check the air tightness of the welding joint.

[0013] Further, the specific parameters of resistance spot welding are as follows:

[0014] Voltage: 70V~150V;

[0015] Pressure: 0.5kN~1.5kN;

[0016] Preload time: 20ms~50ms;

[0017] Holding time: 20ms~50ms.

[0018] Further, the specific parameters of resistance seam welding are as follows:

[0019] Welding current: 1kA~5kA;

[0020] Pressure: 3kN~7kN;

[0021] Welding time: 50ms~200ms;

[0022] Cooling time: 50ms~200ms;

[0023] Welding speed: 200mm / min~500mm / min.

[0024] Furthermore, the bellows is a thin-walled bellows with a thickness of ≤0.6 mm.

[0025] Furthermore, the thickness of the part is ≤3 mm.

[0026] Furthermore, the thickness of the welding ring is 0.5 to 1 times the thickness of the part, and the length of the welding ring is not less than 10 mm.

[0027] Furthermore, the material of the welding ring is the same as the material of the component.

[0028] Furthermore, in the fifth step, the specific method of air tightness inspection is: load the weldment into the air inspection fixture, seal and limit both ends, let compressed air into the inner cavity of the weldment, immerse the entire weldment in alcohol, observe whether there are bubbles coming out of the weld, and conduct an air tightness inspection.

[0029] Beneficial effects of the present invention:

[0030] The present invention changes the structure of the bellows welding end, assembles a welding ring of the same material as the parts on the outside of the thin-wall bellows, and combines the resistance seam welding process to form a weld at the overlap with the bellows. During the welding process, the weld nugget deviation phenomenon can be corrected, and the parts on both sides of the bellows form a qualified penetration rate, and the weld is beautifully formed. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of bellows welding.

[0032] Among them, bellows 1, parts 2, welding ring 3. DETAILED DESCRIPTION

[0033] For thin-walled corrugated pipes with a thickness of less than 0.6 mm, it is easy to produce welding overburning during resistance seam welding. In this regard, the present invention uses an additional welding ring structure to perform resistance seam welding on the corrugated pipe, so that the weld nugget deviation phenomenon can be corrected, and the parts on both sides of the corrugated pipe form a qualified penetration rate, and the weld is beautiful.

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] like Figure 1 The present invention provides a thin-walled corrugated pipe welding method based on resistance seam welding, comprising the following steps:

[0036] The first step is to mechanically polish the inner and outer surfaces of the bellows welding end, the outer surface of the parts and the inner surface of the welding ring to reveal the metallic luster, then use a clean white cloth dipped in acetone to wipe the area to be welded, and dry it after wiping. The surface of the area to be welded is clean and free of foreign matter.

[0037] Furthermore, in the first step, the bellows is a thin-walled bellows with a thickness of ≤0.6 mm.

[0038] The second step is to tightly assemble the bellows, parts and welding ring, wherein the welding ring is assembled on the outside of the bellows, the parts are assembled on the inside of the bellows, and the end face of the welding ring is flush with the end face of the bellows.

[0039] Further, in the second step, the thickness of the part is ≤3mm.

[0040] Furthermore, in the second step, the thickness of the welding ring is 0.5 to 1 times the thickness of the part.

[0041] Further, in the second step, the material of the welding ring is the same as the material of the part.

[0042] The third step is to evenly distribute four-point positioning welding on the assembled components using resistance spot welding.

[0043] Further, in the third step, the positioning welding point is located at the axial center of the welding circle, and the positioning welding ensures that the parts are not loose.

[0044] Further, in the third step, specific parameters of resistance spot welding are: voltage: (70-150) V, pressure: (0.5-1.5) kN, pre-pressing time: (20-50) ms, holding time: (20-50) ms.

[0045] The fourth step is to perform circular welding on the welded parts by resistance seam welding to form a welded joint.

[0046] Further, in the fourth step, specific parameters of resistance seam welding are: welding current: (1-5) kA, pressure: (3-7) kN, welding time: (50-200) ms, cooling time: (50-200) ms, welding speed: (200-500) mm / min.

[0047] Furthermore, in the fourth step, the overlap of adjacent welds of the resistance seam welding is not less than 30% of the weld indentation, and the overlap of the beginning and end of the annular weld is not less than 10 mm.

[0048] The fifth step is to check the air tightness of the welding joint.

[0049] Furthermore, in the fifth step, the weldment is loaded into the gas inspection fixture, sealed and limited at both ends, compressed air is introduced into the inner cavity of the weldment, the entire weldment is immersed in alcohol, and the weld is observed for bubbles to conduct an air tightness inspection.

[0050] Example

[0051] The welding base material is selected with a bellows thickness of 0.2mm, a part thickness of 2mm, and a welding ring thickness of 1.5mm. Before welding, the inner and outer surfaces of the bellows welding end, the outer surface of the part and the inner surface of the welding ring are mechanically polished to reveal the metallic luster, and then a clean white cloth is dipped in acetone to wipe the welding part, and then dried after wiping. The surface of the welding part is clean and free of foreign matter. The bellows, parts and welding rings are tightly assembled, wherein the welding ring is assembled on the outside of the bellows, the parts are assembled on the inside of the bellows, and the end face of the welding ring is flush with the end face of the bellows. The assembled components are evenly distributed four-point positioning welding by resistance spot welding, and the welding parameters are: voltage: 100V, pressure: 1kN, pre-pressure time: 30ms, and pressure holding time: 40ms. Resistance seam welding is used for circular welding of the welding part, and the welding parameters are: welding current: 3kA, pressure: 4kN, welding time: 150ms, cooling time: 100ms, welding speed: 300mm / min to form a welding joint. Weld 10 groups.

[0052] Comparative Example

[0053] The base material for welding is 0.2mm thick bellows and 2mm thick parts. Before welding, the inner and outer surfaces of the bellows welding end, the outer surface of the parts and the inner surface of the welding ring are mechanically polished to reveal the metallic luster, and then a clean white cloth is dipped in acetone to wipe the welded part. After wiping, it is dried. The surface of the welded part is clean and free of foreign matter. The bellows, parts and welding rings are tightly assembled, wherein the welding ring is assembled on the outside of the bellows, the parts are assembled on the inside of the bellows, and the end face of the welding ring is flush with the end face of the bellows. The assembled components are evenly distributed with four-point positioning welding by resistance spot welding. The welding parameters are: voltage: 100V, pressure: 1kN, pre-pressing time: 30ms, holding time: 40ms. The resistance seam welding is used for circular welding of the welded part. The welding parameters are: welding current: 3kA, pressure: 4kN, welding time: 150ms, cooling time: 100ms, welding speed: 300mm / min to form a welded joint. Weld 10 groups.

[0054] The components welded in the embodiment and the comparative example were inspected for weld air tightness. It is stipulated that if there is no bubble overflow at the weld, it means that the weld air tightness is qualified. The results show that: the weldment using the welding ring in the patent has a weld air tightness qualification rate of 100%, and the weld air tightness is good; the weldment not using the welding ring in the patent has a weld air tightness qualification rate of 70%, and the weld air tightness performance is poor.

[0055] The present invention utilizes an external welding ring structure to perform resistance seam welding on the bellows, so that the deviation of the weld nugget can be corrected, and parts on both sides of the bellows form a qualified penetration rate, and the weld is beautifully formed.

[0056] The above is only a specific embodiment of the present invention, and the present invention is described in detail. The unexplained part is a conventional technology. However, the protection scope of the present invention is not limited to this. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A thin-walled corrugated pipe welding method based on resistance seam welding, characterized in that: The following steps are involved: The first step is to mechanically polish the inner and outer surfaces of the bellows welding end, the outer surface of the parts and the inner surface of the welding ring, and then wipe them clean with acetone and dry them; The second step is to tightly assemble the bellows, parts and welding ring, wherein the welding ring is assembled on the outside of the bellows, the parts are assembled on the inside of the bellows, and the end face of the welding ring is flush with the end face of the bellows; The third step is to evenly distribute four points of positioning welding along the circumference of the assembled components by resistance spot welding; The fourth step is to perform annular welding on the middle part of the welding circle by using resistance seam welding to form a welding joint; The fifth step is to check the air tightness of the welding joint.

2. The method according to claim 1, characterized in that The specific parameters of resistance spot welding are as follows: Voltage: 70V~150V; Pressure: 0.5kN~1.5kN; Preload time: 20ms~50ms; Holding time: 20ms~50ms.

3. The method according to claim 1, characterized in that The specific parameters of resistance seam welding are as follows: Welding current: 1kA~5kA; Pressure: 3kN~7kN; Welding time: 50ms~200ms; Cooling time: 50ms~200ms; Welding speed: 200mm / min~500mm / min.

4. The method according to claim 1, characterized in that: The bellows is a thin-walled bellows with a thickness of ≤0.6mm.

5. The method according to claim 1, characterized in that The thickness of the parts is ≤3mm.

6. The method according to claim 1, characterized in that The thickness of the welding ring is 0.5 to 1 times the thickness of the part, and the length of the welding ring is not less than 10mm.

7. The method according to claim 6, characterized in that The material of the welding ring is the same as the part material.

8. The method according to claim 1, characterized in that The fifth step is to check the air tightness. The specific method is: put the weldment into the air inspection fixture, seal and limit both ends, let compressed air into the inner cavity of the weldment, immerse the entire weldment in alcohol, observe whether there are bubbles coming out of the weld, and conduct an air tightness check.

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