A thin-walled cylindrical part welding forming process and a welded thin-walled cylindrical part

Abstract

The present application relates to a kind of thin-walled cylinder welding forming process and welded thin-walled cylinder, it is mainly used for metal thin-walled cylinder welding and post-welding treatment process to prevent welding deformation too large.Wherein, thin-walled cylinder diameter (50-1500) mm, cylinder wall thickness range is (0.5-20) mm.Rational welding process is used to solve the problem that product is scrapped due to serious welding deformation.Product processing verification shows that the welding forming control process meets the welding quality requirements of the thin-walled cylinder, and better solves the technical problem of large welding deformation during the welding process of thin-walled cylinder, so that the roundness requirement of the entire thin-walled cylinder assembly after welding is not more than 0.3mm.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a welding forming process for thin-walled cylindrical parts. Background Technology

[0002] A certain type of air duct is a key product for aero-engines, providing pressurization and pressure stabilization for the aero-engine ventilation system. It is made of In718, a high-temperature alloy, which is a Fe-Ni-Cr based precipitation-hardening high-temperature alloy. During the welding process of the thin-walled cylinder's circumferential weld, varying degrees of concave deformation occur in the heat-affected zones on both sides of the cylinder shell. This can cause excessive deviations in the overall coaxiality and local roundness of the cylinder, and may also lead to stress concentration, thus affecting the cylinder's load-bearing capacity. The welding characteristics of this thin-walled cylinder are: large diameter, thin wall thickness, large welding deformation, and irregular post-weld deformation. Therefore, controlling welding deformation to ensure acceptable roundness and the amount of misalignment of the base material on both sides of the butt joint is a key technical challenge to be solved. Summary of the Invention

[0003] This invention discloses a welding forming process for thin-walled cylindrical components and the resulting thin-walled cylindrical components, primarily used to prevent excessive welding deformation during the welding and post-weld processing of thin-walled metal cylindrical components. The diameter of the thin-walled cylinder is (50-1500) mm, and the wall thickness ranges from (0.5-20) mm. A reasonable welding process is employed to solve the problem of severe welding deformation leading to product scrap. Through product processing verification, this welding forming control process meets the welding quality requirements of the thin-walled cylindrical components, effectively solving the technical problem of large welding deformation during the welding process, ensuring that the roundness of the entire thin-walled cylindrical assembly after welding does not exceed 0.3 mm.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A welding forming process for thin-walled cylindrical components includes the following steps:

[0006] S1: Welding area cleaning. Before welding, use a clean silk cloth soaked in anhydrous ethanol to wipe the welding area of ​​the cylinder to be welded clean and dry it.

[0007] S2: Fix the cylindrical part to be welded; use the support rod fixture to clamp the cylindrical part to be welded on the welding equipment. First, use a dial indicator to perform a circumferential rotation test on the clamped cylindrical part to be welded, record the position points of the major axis and minor axis of the ellipse of the cylindrical part, and mark them.

[0008] S3: Determine the positioning solder joint and arc starting point based on the location points marked in S2.

[0009] A: Increase the length of the positioning weld points: Deviations in the roundness of the cylinder will increase the welding assembly stress. Coupled with welding thermal stress, the positioning weld points are prone to cracking, causing them to fail and resulting in excessive deformation. To prevent cracking of the positioning points, the first step is to increase the length of the positioning weld points to enhance their resistance to deformation. The length of the positioning weld points is increased from 3-5mm to 15-20mm. At positioning points with poor roundness, a multi-segment positioning method is used to avoid weld point cracking caused by large deformation stress.

[0010] B: Adjust the arc starting point to avoid high point thermal strain: Mark the roundness of the cylinder weld joint and record the position points of the major and minor axes of the cylinder ellipse. Determine the arc starting point of the circumferential weld about 20-30mm in front of the major axis point of the cylinder weld. When welding, weld the part with the larger roundness first.

[0011] S4: Start welding. Weld according to the arc starting point and positioning welding point obtained in S3. The selection of welding process parameters is as follows: For the circumferential weld of the cylinder, preheat welding is performed first with medium and small beam current (about half the size of the welding beam current). When welding, the upper focusing mode is selected. After welding, maintain the vacuum environment of the chamber for 5-10 minutes before opening the hatch.

[0012] S5: Post-weld heat treatment. After welding in S4, the roundness of the weld seam and its vicinity of the cylindrical part to be welded is measured and analyzed to find the major and minor axes of the ellipse of the cylindrical part to be welded in this area. Then, external clamps and internal support fixtures are used for heat treatment to prevent deformation. Finally, it is placed in the heat treatment equipment.

[0013] Preferably, the support rod fixture includes an intermediate support rod disposed inside the cylindrical workpiece to be welded, with positioning discs connected to the welding rotation equipment at both ends of the intermediate support rod via threads; this serves to bear weight and tighten, ensuring the product is securely clamped during welding rotation. During welding or clamping alignment, the workpiece rotates with the chuck and is secured by the support rod and nuts, preventing localized cracking of the fit gaps between components due to its own weight.

[0014] Preferably, the inner support fixture includes two opposing arc-shaped top plates, the arc-shaped top plates having the same curvature as the cylinder, an adjusting threaded rod between the two arc-shaped top plates, and a threaded sleeve that mates with the adjusting threaded rod on the inner side of the arc-shaped top plates. The outer clamp includes opposing semi-circular clamps.

[0015] Preferably, the support point of the inner support fixture is located at the short axis of the thin cylindrical part, and the force point of the outer clamp is located at the long axis of the thin cylindrical part.

[0016] Preferably, the drying temperature in step S1 is 30-80℃ and the drying time is 5-20 minutes.

[0017] Preferably, the setting parameters for the upper focusing welding in step S4 are: focusing current of 1265-1275mA, accelerating voltage of 60-70KV, welding beam current of 18-20mA, and welding speed of 400-600mm / min.

[0018] Preferably, the points for the circumferential rotation dial indicator test in S2 include a first measuring point located at both ends of the cylinder, a second measuring point located 5-10mm on the left and right sides of the weld, and a third measuring point located in the middle of the cylinder to be welded.

[0019] A thin-walled cylindrical component welded using a thin-walled cylindrical component welding forming process, wherein the diameter of the thin-walled cylinder is 50-1500mm, the thickness of the thin-walled cylinder wall is 0.5-20mm, and the overall roundness deviation of the thin-walled cylinder after welding cannot exceed 0.3mm.

[0020] The present invention has the following effects:

[0021] 1. This process has been verified through product processing. This welding method effectively solves the technical challenge of large welding deformation in the butt weld of thin-walled cylinders, ensuring that the roundness requirement of the thin-walled cylinder assembly does not exceed 0.3mm. Analysis of the electron beam welding of an air duct for a certain type of aero-engine revealed the causes of welding defects. Improvements to the welding joint, tooling design, and optimization of welding process parameters were implemented, resulting in excellent welds with well-controlled welding deformation, meeting the welding quality requirements of thin-walled cylinder products. This method has been applied to the welding of an air duct for a certain type of aero-engine and can provide a reliable reference for the production and processing of thin-walled cylinders and similar structural products.

[0022] 2. Considering the large weight of the product, a support rod fixture was designed for this process. This fixture is clamped and positioned at both ends, with the central support rod made of stainless steel. Threads are machined at both ends, and nuts are tightened to secure the positioning fixture at both ends. This provides load-bearing and tensioning functions, ensuring the product is firmly clamped during welding and rotation. During welding or clamping and alignment, the workpiece rotates with the chuck and is held in place by the support rod and nuts, preventing cracking of localized gaps between components due to its own weight. Attached image description:

[0023] Figure 1 This is a schematic diagram showing the welding positions of a thin-walled cylindrical structure.

[0024] Figure 2 This is a schematic diagram of the welding clamping process;

[0025] Figure 3 Schematic diagram of the welding fixture for the support rod;

[0026] Figure 4 A schematic diagram showing the points for determining the roundness of the shell cylinder;

[0027] Figure 5 Diagram of external clamp, internal support clamp, and combination of external clamp and internal support;

[0028] Among them, 101-arc top plate; 102-adjustable threaded rod; 103-threaded sleeve; 104-semi-circular clamp; 105-thin cylindrical part; 106-intermediate support rod; 107-positioning plate; 108-top cone; 109-rotary chuck. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0030] Example 1:

[0031] A welding forming process for thin-walled cylindrical components includes the following steps:

[0032] S1: Welding area cleaning. Before welding, use a clean silk cloth soaked in anhydrous ethanol to wipe the welding area of ​​the cylinder to be welded clean and dry it.

[0033] S2: Fix the cylindrical part to be welded; use the support rod fixture to clamp the cylindrical part to be welded on the welding equipment. First, use a dial indicator to perform a circumferential rotation test on the clamped cylindrical part to be welded, record the position points of the major axis and minor axis of the ellipse of the cylindrical part, and mark them.

[0034] S3: Determine the positioning solder joint and arc starting point based on the location points marked in S2.

[0035] A: Increase the length of the positioning weld points: Deviations in the roundness of the cylinder will increase the welding assembly stress. Coupled with welding thermal stress, the positioning weld points are prone to cracking, causing them to fail and resulting in excessive deformation. To prevent cracking of the positioning points, the first step is to increase the length of the positioning weld points to enhance their resistance to deformation. The length of the positioning weld points is increased from 3-5mm to 15-20mm. At positioning points with poor roundness, a multi-segment positioning method is used to avoid weld point cracking caused by large deformation stress.

[0036] B: Adjust the arc starting point to avoid high point thermal strain: Mark the roundness of the cylinder weld joint and record the position points of the major and minor axes of the cylinder ellipse. Determine the arc starting point of the circumferential weld about 20-30mm in front of the major axis point of the cylinder weld. When welding, weld the part with the larger roundness first.

[0037] S4: Start welding. Weld according to the arc starting point and positioning welding point obtained in S3. The selection of welding process parameters is as follows: For the circumferential weld of the cylinder, preheat welding is performed first with medium and small beam current (about half the size of the welding beam current). When welding, the upper focusing mode is selected. After welding, maintain the vacuum environment of the chamber for 5-10 minutes before opening the hatch.

[0038] S5: Post-weld heat treatment. After welding in S4, the roundness of the weld seam and its vicinity of the cylindrical part to be welded is measured and analyzed to find the major and minor axes of the ellipse of the cylindrical part to be welded in this area. Then, external clamps and internal support fixtures are used for heat treatment to prevent deformation. Finally, it is placed in the heat treatment equipment.

[0039] The support rod fixture includes an intermediate support rod 106 installed inside the cylindrical part to be welded. Positioning discs 107, connected to the welding rotation equipment, are threaded onto both ends of the intermediate support rod. This serves to bear weight and provide tension, ensuring the product is securely clamped during welding rotation. During welding or clamping alignment, the workpiece rotates with the chuck and is secured by the support rod and nuts, preventing localized cracking of the fit between components due to its own weight. The two ends of the cylindrical part to be welded are respectively fixed by a top cone 108 and a rotating chuck 109 for subsequent processing.

[0040] As a preferred embodiment, the internal support fixture includes two arc-shaped top plates 101 installed opposite each other, the arc-shaped top plates having the same curvature as the cylinder, an adjusting threaded rod 102 installed between the two arc-shaped top plates, a threaded sleeve 103 that mates with the adjusting threaded rod installed on the inner side of the arc-shaped top plates, and an external clamp including a semi-circular clamp 104 installed opposite each other.

[0041] As a preferred embodiment, the support point of the inner support fixture is located at the short axis of the thin cylindrical part, and the force point of the outer clamp is located at the long axis of the thin cylindrical part.

[0042] As a preferred embodiment, the drying temperature in step S1 is 30-80℃ and the drying time is 5-20min.

[0043] As a preferred embodiment, the installation parameters for the upper focusing welding in step S4 are: focusing current of 1265-1275mA, accelerating voltage of 60-70KV, welding beam current of 18-20mA, and welding speed of 400-600mm / min.

[0044] As a preferred embodiment, the points for the circumferential rotation dial indicator test in S2 include the first measuring point located at both ends of the cylinder, the second measuring point located 5-10mm on the left and right sides of the weld, and the third measuring point located in the middle of the cylinder to be welded.

[0045] A thin-walled cylindrical component 105 is welded using a thin-walled cylindrical component welding forming process. The diameter of the thin-walled cylinder is 50-1500mm, the thickness of the thin-walled cylinder wall is 0.5-20mm, and the overall roundness deviation of the thin-walled cylinder after welding cannot exceed 0.3mm.

[0046] Based on the above plan, a physical object was produced, with the following details:

[0047] 1.1 Structural Composition

[0048] The air duct (inner diameter Φ105, wall thickness 3mm) has the following structure: Figure 1 As shown, the material, In718 high-temperature alloy bar stock, is divided into three sections: front, middle, and rear (as shown below). Figure 1 The thin-walled cylinders are first machined into cylindrical shapes, and then vacuum electron beam welded through a circumferential weld. The roundness of the entire assembly after welding must not exceed 0.3 mm.

[0049] By analyzing the electron beam welding of air ducts for a certain type of aero-engine, the causes of welding defects were identified. Improvements were made to the weld joints, tooling design, and welding process parameters, resulting in excellent welds with well-controlled welding deformation, thus meeting the welding quality requirements for thin-walled cylinder products. This method has been applied to the welding of air ducts for a certain type of aero-engine and can provide a reliable reference for the manufacturing process of thin-walled cylinders and similar structural products.

[0050] Based on the characteristics of the product, such as its large weight, we designed a set of support rod tooling, as follows: Figure 3 As shown, this fixture is clamped and positioned at both ends. The central support rod is made of stainless steel, and the two ends are threaded and tightened with nuts. The positioning fixture at both ends can bear weight and provide tension, ensuring that the product is firmly clamped during welding and rotation. During welding or clamping and alignment, the workpiece rotates with the chuck and is secured by the support rod and nuts, preventing localized cracking of the fit between components due to its own weight.

[0051] The roundness of the thin-walled cylinder shell is measured using a micrometer. Figure 5 The roundness data were taken at seven locations on the shell cylinder, namely A, B, C, D, E, F, and G. Locations A and G are at both ends of the cylinder; locations B, C, E, and F are located at (5-10) mm on the left and right sides of the two welds, respectively; and location D is in the middle of the middle section of the cylinder.

[0052] A welding forming process for thin-walled cylindrical components specifically includes the following steps:

[0053] 1. Pre-welding preparation and welding process measures:

[0054] 1) Before welding, wipe the welding area clean with a clean cloth soaked in anhydrous ethanol and dry it. The drying temperature is (30-80)℃ and the time is (5-10)min.

[0055] 2) We first use a dial indicator to perform a circumferential rotation test on the clamped workpiece to be welded, record the position points of the major and minor axes of the ellipse of the cylinder, and mark them.

[0056] ① Increase the length of the locating weld points

[0057] Deviance in the roundness of parts increases welding assembly stress. Combined with welding thermal stress, this makes locating welds prone to cracking, leading to weld failure and ultimately excessive deformation. To prevent cracking, we first increased the length of the locating welds to enhance their resistance to deformation. Therefore, we increased the length of the locating welds from 3-5 mm to 15-20 mm. Furthermore, at locating points with poor roundness, we used a multi-segment locating method to avoid weld cracking caused by excessive deformation stress.

[0058] ②Preheating distribution welding is adopted

[0059] Medium and low beam current preheating is used, which is equivalent to welding the weld in two layers. This has a preheating effect, prevents uneven heating and excessive heating of the weld, and reduces the generation of defects such as porosity or cracks.

[0060] ③ Adjust the starting point of the arc to avoid high point thermal strain.

[0061] We can take advantage of the small thermal stress deformation of the weld in the early stages of welding. When the misalignment is small, we can adjust the arc starting point of the weld to avoid the thermal stress deformation at higher points. That is, we use a roundness gauge to mark the roundness of the weld joint of the product and record the positions of the major and minor axes of the ellipse of the cylinder. We then determine the arc starting point of the circumferential weld about (20-30) mm in front of the major axis point of the cylinder weld. During welding, we weld the part with the larger roundness first, thereby eliminating the risk of excessive deformation caused by the superposition of welding thermal stress deformation and the roundness deviation of the pre-welding tack weld.

[0062] ④ Selection of welding process parameters

[0063] The air duct has two circumferential welds. Preheating welding is performed first using a medium to small beam current (approximately half the welding beam current). During the actual welding, an upward focusing method is selected, with a focusing current of (1265-1275) mA, an accelerating voltage of (60-70) KV, a welding beam current of (18-20) mA, and a welding speed of (400-600) mm / min. After welding, the chamber is kept in a vacuum environment for (5-10) min before the hatch is opened.

[0064] 2. Post-weld heat treatment process

[0065] To ensure the joint performance of the Inconel 718 thin-walled cylinder after welding, we employ an aging treatment process. Before loading the cylinder into the furnace for heat treatment, we first measure and analyze the roundness of the weld seam and its vicinity to determine the major and minor axes of the cylinder's ellipse in this area. We then use an external clamp and internal support fixture to prevent deformation during heat treatment. The internal support fixture uses a threaded device to adjust the support distance, with the support point located at the minor axis of the thin-walled cylinder. The external clamp fixture is also threaded, with the stress point located at the major axis. The entire roundness straightening fixture and clamping process are illustrated in [illustration missing]. Figure 5 .

[0066] In this invention, unless otherwise explicitly specified and limited, for example, it can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two elements or an interaction between two elements. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

Claims

1. A welding forming process for thin-walled cylindrical parts, characterized in that: Includes the following steps: S1: Welding position cleaning. Before welding, use a clean silk cloth soaked in anhydrous ethanol to wipe the welding position of the cylinder part clean and dry it. S2: Fix the cylindrical workpiece to be welded; use the support rod fixture to clamp the cylindrical workpiece to be welded onto the welding equipment, first use a dial indicator to perform a circumferential rotation test on the clamped cylindrical workpiece to be welded, record the position points of the major axis and minor axis of the ellipse of the cylindrical workpiece, and mark them; the support rod fixture includes an intermediate support rod set inside the cylindrical workpiece to be welded, and the two ends of the intermediate support rod are provided with positioning plates connected to the welding rotation equipment by threads; S3: Determine the positioning solder joint and arc starting point based on the location points marked in S2. A: Increase the length of the positioning weld points: Deviations in the roundness of the cylinder will increase the welding assembly stress. Coupled with welding thermal stress, the positioning weld points are prone to cracking, causing them to fail and resulting in excessive deformation. To prevent cracking of the positioning weld points, the first step is to increase the length of the positioning weld points to enhance their resistance to deformation. The length of the positioning weld points is increased from 3-5mm to 15-20mm, and at positioning points with poor roundness, a multi-segment positioning method is used to avoid weld point cracking caused by large deformation stress. B: Adjust the arc starting point to avoid high point thermal strain: Mark the roundness of the cylinder weld joint and record the position points of the major and minor axes of the cylinder ellipse. Determine the arc starting point of the circumferential weld 20-30mm in front of the major axis point of the cylinder weld. When welding, weld the part with the larger roundness first. S4: Start welding. Weld according to the arc starting point and positioning welding point obtained in S3, and select welding process parameters. For the circumferential weld of the cylinder, preheat welding is performed first. When welding, select the upper focusing method. After welding, maintain the vacuum environment of the chamber for 5-10 minutes before opening the hatch. S5: Post-weld heat treatment. After welding in S4, the roundness of the weld seam and its vicinity is measured and analyzed to find the major and minor axes of the ellipse of the cylindrical part to be welded. Then, external clamps and internal support fixtures are used for heat treatment to prevent deformation. Finally, it is placed in the heat treatment equipment. The internal support fixture includes two opposing arc-shaped top plates, the arc-shaped top plates having the same curvature as the cylinder, an adjusting threaded rod between the two arc-shaped top plates, and a threaded sleeve that mates with the adjusting threaded rod on the inner side of the arc-shaped top plates. The external clamp includes opposing semi-circular clamps. The support point of the inner support fixture is located at the short axis of the thin-walled cylindrical component, and the force point of the outer clamp is located at the long axis of the thin-walled cylindrical component. In step S1, the drying temperature is 30-80℃ and the drying time is 5-20 minutes. The setting parameters for the upper focusing welding in step S4 are: focusing current 1265-1275mA, accelerating voltage 60-70kV, welding beam current 18-20mA, and welding speed 400-600mm / min. The points for the circumferential rotation dial indicator test in step S2 include the first measuring point at both ends of the cylinder, the second measuring point 5-10mm on the left and right sides of the weld, and the third measuring point in the middle of the cylinder to be welded.

2. A thin-walled cylindrical component welded using the thin-walled cylindrical component welding forming process as described in claim 1, characterized in that: The diameter of the thin-walled cylindrical component is 50-1500mm, the wall thickness ranges from 0.5-20mm, and the overall roundness deviation of the thin-walled cylindrical component after welding shall not exceed 0.3mm.

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